GB2194020A

GB2194020A - Apparatus for damping oscillations

Info

Publication number: GB2194020A
Application number: GB08715822A
Authority: GB
Inventors: Johann Jackel; Wolfgang Reik
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1986-07-05
Filing date: 1987-07-06
Publication date: 1988-02-24
Anticipated expiration: 2007-07-06
Also published as: GB2194020B; JPH0771530A; JPH0771529A; FR2707102A1; IT1221951B; FR2754325B1; DE3721711C2; IT8721178A0; FR2707102B1; FR2688846A1; FR2754324B1; FR2601103A1; FR2688846B1; JP2713340B2; BR8703425A; DE3721711A1; GB8715822D0; FR2754325A1; ES2009144A6; JP3400727B2

Abstract

Apparatus for damping torsional oscillations, for example between an engine and a drive train, comprises a divided flywheel with a viscous damping material, such as grease, in an annular passage (51) in one of the flywheel elements (3) and closed by a flange body (41) of the other flywheel element (4). A set of arcuate precurved springs (45) within the passage (51) engage supports carried by the flywheel element (3) and flange body (41). The springs (45) extend around 70 to 96% of the passage circumference and permit relative angular movement between the flywheel elements (3) and (4) of at least 25 DEG in each direction from the central position. <IMAGE>

Description

SPECIFICATION Apparatus for damping oscillations The invention relates to an apparatus for damping oscillations, in particular between an engine and a drive train, with a damping arrangement to be provided between two flywheel elements, wherein the input member is the one flywheel element which can be connected to the engine and the output member is the other flywheel element which can be connected to the drive train, for example by way of a clutch.

Apparatus of that kind have as damping means generally between the flywheel elements both force storage means such as coil springs which are operative in the peripheral direction and which store elastic energy and also force storage means which are operative in the axial direction and which in co-operation with frictional or sliding linings produce a friction effect, that is to say a hysteresis action, which is in parallel relationship with the force storage means which are operative in the peripheral direction.

Furthermore, with the previous apparatuses of the kind set forth in the opening part of this specification, a comparatively small rotationally elastic relative rotary movement is possible between the flywheel elements, for which reason the damping rate of the damping means operative between the flywheel elements is comparatively high at least over a large range of such relative rotary movement.

For many situations of use however it would be advantageous to provide a better damping effect in respect of the oscillations if there were large relative rotary movements between the flywheel elements, as more specifically in that way it would be possible better to damp large-amplitude oscillations. The present invention was based on the problem of improving such apparatuses and in particular the damping action thereof, so as to provide for optimum filtering of the oscillations which occur between the engine and the transmission, both at low and at high speeds of rotation, at resonance speeds of rotation, when starting up or when switching off, or the like.Furthermore the invention seeks to provide the option of being able to adapt the damping characteristic, that is to say the degree of energy dissipation, to the different noise and oscillation aspects of a vehicle under different operating conditions and other influences. In addition the invention seeks to provide that the apparatus according to the invention can be produced in a particularly simple and inexpensive manner. In particular the invention seeks to provide, by means of design features, that the level of production expenditure is low by using the maximum amount of non-cutting production. The invention further seeks to pm- vide that the amount of wear is minimized and the operating life is increased.

In accordance with the invention that is achieved in that the apparatus according to the invention has at least three of the features set out below: a) the damping arrangement includes at least one annular passage of practically closed cross-section, which is formed by components of the one flywheel element and which is at least partially filled with viscous medium such as a pasty agent and in which at least two force storage means such as springs are contained and supported on the same diameter, b) the annular passage is, possibly except for a small gap, closed by a flange body which is non-rotatably connected to the second flywheel element and which projects radially into the annular passage and which forms the other support regions for the springs, c) the springs between the flywheel elements permit at least a relative rotational movement of + 25 degrees, starting from a centre position, d) with "n" springs on the same diameter wherein 2 4 n c 4, the individual springs extend over 70 to 96% of an angular sector, wherein the angular sector is 360 degrees/n, e) the springs extend over 70 to 96% of the angular periphery of the apparatus, and f) the springs arranged in the passage-like receiving means are pre-curved at least approximately to the radius on which they are arranged.

The features according to the invention provide a construction for the apparatus which ensures satisfactory guidance for the springs which are accommodated in the annular passage so that those springs can be comparatively long and a large angle of rotational movement between the two flywheel elements is thus possible. In that way it is possible to achieve improved damping of the oscillations which occur between the flywheel elements as, due to the large relative rotational movements possible between the flywheel elements, the damping rate which is operative therebetween can be comparatively low over a large or even over almost the entire angle of rotary movement. The greater the possible angle of rotary movement, the lower the damping rate can be in that construction.

Therefore the construction of the apparatus according to the invention makes it possible to use long one-piece springs of comparatively low stiffness but with a long spring travel, which thus permit the above-mentioned low damping rate. By virtue of the large angle of rotational movement which can be produced, with at the same time a low damping rate, both large-amplitude oscillations or high alternating torque peaks as well as low-amplitude oscillations or lower alternating torques can be damped or filtered. That means that satisfactory damping of the oscillations which occur can be achieved practically under all operating conditions of the engine.It may be particularly advantageous for the spring rate or stiffness of the resilient damper formed by the springs between the flywheel elements to be of the order of magnitude of between 2 and 20 Nm/degree, preferably between 4 and 15 Nm/degree. In that connection it may be particularly desirable for the spring rate or stiffness to be present, over at least an angle of rotary movement of 15 degrees between the two flywheel elements, in the pulling direction and/or in the pushing direction.Furthermore, the displacement of or turbulence in the viscous medium contained in the annular passage, which occurs upon compression and relief of the long springs and as a result of the movement of the regions of the flange bcdy which project into the annular passage mean that it is possible to produce a viscous or hydraulic damping action which changes in dependence on the angular speeds or accelerations which cccur by virtue of torque fluctuations or rotational oscillations between the two flywheel elements. A further advantage is that the damping effect which is caused by the viscous medium is variable in dependence on the speed of rotation of the engine.Therefore, in dependence on the angular speed as between the two flywheel elements and in dependence on the speed of rotation of the apparatus, the damping performance or hysteresis and thus the entire damping characteristic of the apparatus can be altered. Therefore the viscous medium disposed in the annular passage can damp not only large-amplitude oscillations which are caused by rotary torque pulses or alternating moments, but also low-amplitude oscillations which have to be damped with a correspondingly low level of hysteresis and which occur in particular under on-load conditions. That can be attributed to the fact that the pressure which builds up in the viscous medium is dependent on the instantaneous speed with which a -given volume of the viscous medium is displaced.That therefore means that the damping capacity of the viscous medium which is accommodated at least in the annular passage is dependent on whether shcck moments or high alternating moments or lower fluctuations in torque cccur between the two flywheel masses. It is therefore possible to achieve practically automatic regulation of the damping action.

The use of pre-curved springs means that the stresses which occur therein upon compression thereof can be reduced while in addition assembly can be facilitated.

The support regions for the springs in the annular passage may advantageously be formed by radial arms or projections which are formed on the flange body and which open into the radial regions of the annular passage. In that respect, radially outwardly of the support regions, the arms or projections may go into a web portion which engages over the springs in the peripheral direction.

The web portions which, as considered in the peripheral direction, connect each two radial arms or projections, may be accommodated in an annular recess which adjoins the annular passage at a radially outward location.

As considered in the radial direction, the web portions may be of such a configuration relative to the annular passage that at least when the apparatus is rotating, the springs are radially supported substantially at said portions. That may be advantageous in particular when at least individual ones of the force storage means which are accommodated in the annular passage come into operation successively, that is to say form a multi-stage rotationally elastic damping arrangement, and the springs which come into operation only after an angle of relative rotary movement between the two flywheel elements are firstly positioned by way of the flange in the peripheral direction as in that case, during the angle of rotary movement in which those springs are not compressed, they rotate with the component, namely the flange, against which they are radially supported, so that it is possible to avoid additional frictional damping between those springs and the boundary surfaces of the annular passage.

A particularly advantageous structure of the invention may provide that the annular passage is formed by two shell-like bodies, wherein at least one of those bodies may be a shaped sheet metal member.

It may be particularly advantageous for the annular passage to be formed by two halfshell-like shaped sheet metal members, wherein they may be a component of the flywheel element connected to the engine, or may even form that flywheel element. An advantage of such shaped sheet metal members over members which are produced by cutting machining lies in a substantially reduced level of production expenditure. Furthermore, when dealing with sheet metal members which are produced by stamping, drawing and pressing, it is possible to have a large number of advantageous design configurations, thus for example even passage cross-sections which differ from the rotationally symmetrical shape may be produced in an inexpensive fashion.

The peripheral support means for supporting the springs in the annular passage may also be formed by impressed portions or shaped portions of pocketlike configuration so that there is no need for additional elements to provide that function.

The support means or abutments in the annular passage for the end regions of the springs may however also be formed in a simple fashion by individual elements which are fitted into the annular passage which is otherwise continuous over the periphery of the arrangement. Those elements may be formed by plates or blocks which are riveted in to posi tion, by shaped rivets, or by shaped members which are welded into place.

In order to provide for satisfactory actuation of the springs accommodated in the annular passage, it is advantageous if a pocket-like shaped portion or another abutment element is provided, in the neutral position of the damper or the apparatus, on both sides of an arm or projection on the flange.

In order to produce a multi-stage rotationally elastic damping action, at least in one direction of rotation, starting from a central position or a central range of the two flywheel elements relative to each other, it may be advantageous for at least one arm or projection on the flange body to be of a smaller extent, as considered in the peripheral direction, relative to the support means in the annular passage, which are provided on both sides of said arm or projection. In that connection the arms or projections and the support means may be so arranged relative to each other, in the above-mentioned starting position, that the actuating regions thereof are displaced relative to each other in both directions of rotation, thus providing a multi-stage rotationally elastic damping effect in both directions of rotation.

In the above-mentioned starting position however the actuating regions of the projections for the force storage means and of the support means may also be-flush on one side so that in that case the arrangement provides a stepped rotationally elastic damping action only in one direction of rotation.

However the actuating regions of the projections and the support means may also be displaced relative to each other, with respect to the spring ends, in such a way that there is no springing effect about the neutral position of the relative rotary movement between the two flywheel elements, over a certain angle, so that in that case practically no or only a hydraulic or viscous and/or frictional damping action can occur. That damping action may be very slight.

It is advantageous for the arms or projections on the flange body to extend over a shorter distance than the support means of the annular passage particularly in apparatuses in which the spring or springs which is or are initially not compressed is or are fixed by the support means of the annular passage, in the peripheral direction.

In the case of apparatuses in which the force storage means which only come into operation after a relative angle of rotational movement as between the flywheel elements rotate with the flange body over that angle of relative rotary movement, it may be desirable for at least one arm or projection on the flange body to be of greater extent, as considered in the peripheral direction, than the support means in the annular passage, which are provided on both sides of that arm or projection. In that respect the actuation regions of the arms or projections and the support means may be displaced relative to each other only in one direction of rotation or also in both directions of rotation.

In regard to operation of the apparatus, it may be-particularly advantageous for intermediate layers to be provided at least between some of the projections on the flange body and the spring ends which are theretowards, the intermediate layers having at least a crosssectional region which is at least approximately adapted to the cross-section of the annular passage which accommodates the springs. By virtue of such a configuration of the intermediate layers, they act in the annular passage, upon a relative rotary movement between the two flywheel elements, as displacement pistons for displacing the viscous medium in the annular passage.In order to provide for better guidance of the spring ends, the intermediate layers may be provided with an extension portion projecting into the interiors of the springs, on the side of each intermediate layer which is towards the respective end of a spring. In order to permit the extension portions to engage automatically into the ends of the respective springs, they may have a slightly tapering region which towards the end becomes a portion which has a larger taper angle or which is of a part-spherical configuration. In that way it is possible to ensure that, if an intermediate layer or spring cup slips or is pushed out of the end of a spring, in operation of the arrangement, the spring cup can fit into the spring again, when the spring is relieved of stress or when the spring cup is put under load, without the spring or the spring cup suffering damage.

Because the intermediate layers or spring cups form displacement pistons for the viscous medium in the annular passage, they may advantageously be utilized for controlling the damping action produced by the viscous medium. Thus, it is possible in a particularly simple manner to employ the piston-like intermediate layers to determine the quantitative through-flow rate or the displaced volume of viscous medium, over a given angle of relative rotary movement between the two flywheel elements, thereby to produce a defined, characteristic damping performance in dependence on given operating parameters. The resistance to rotary movement which is generated by the viscous medium can be altered in a simple manner by altering at least one through-flow cross-section for the viscous medium.That can be achieved for example by the annular passage not being of constant cross-section at least over portions of the longitudinal extent of at least one spring which is provided at both ends with intermediate layers or spring cups. In the event of a relative movement between the annular passage and an intermediate layer therefore the free cross-section between the annular passage and the in termediate layer may alter in dependence on the angle of rotary movement. In that connection it may be desirable for at least some of the regions of the annular passage, which are in the end portions of the non-compressed springs, to be enlarged in cross-section relative to the other regions of the annular passage. Such cross-sectional enlargements may extend progressively over a given angular range of rotary movement, or the variations in cross-section may also be abrupt.In order to permit satisfactory guidance of the intermediate layers and the force storage means at a radially outward location, it is desirable for such enlargements in cross-section of the annular passage to be provided in the region of the inner half of the passage.

The damping action produced by the intermediate layers in conjunction with the viscous medium may further be altered by introducing axial cut-out portions or axial recesses, into the intermediate layers.

In regard to operation of the apparatus, it may be advantageous for the projections on the flange bcdy to have noses which point in the peripheral direction and which engage into a recess in the respective intermediate layer.

The noses on the projections on the flange body are of such a configuration or are so arranged, with respect to the recess of the intermediate layer which is respectively associated therewith, that at least the end regions of the springs are kept out of contact with the radially outward regions of the annular passage, by way of the intermediate layers.

The noses on the projections on the flange body may be of such a configuration that, when the intermediate layers are brought into operation, the latter are pulled slightly radially inwardly by the noses and are thus lifted away from the wall of the annular passage.

That provides that, even at a high speed rotation, at least some of the end turns of the springs do not come to bear against the shelllike bodies which form the annular passage, and can thus spring freely. It may be advantageous in that respect for the openings or recesses in the intermediate layers to be annular in cross-section and for the noses on the projections on the flange body to have at least regions which are adapted to the recesses. That may be effected for example by subjecting the noses which have first been stamped out to an impressing operation. The recesses in the intermediate layers may be of a conical or spherical configuration, as considered in the axial direction of the springs, and may form blind holes.

In accordance with a development of the invention, at least one further spring group of the damping arrangement may be provided radially inwardly of the annular passage. For many situations of use it may be advantageous for that further spring group to be arranged in parallel relationship with the first spring group in the annular passage, between the flywheel elements. In that connection the arrangement of the individual springs of the first and further spring groups between the two flywheel elements may be such that at least some springs of both spring groups come into operation in a step-wise manner, that is to say in angularly displaced relationship, and/or at least individual springs of at least one spring group come into operation in a step-wise manner, that is to say in angularly displaced relationship.

In accordance with a further embodiment of the invention the first spring group disposed in the annular passage and the radially further inwardly disposed further spring group may be arranged in series relationship between the flywheel elements The springs which are connected in parallel relationship within said spring groups may also form various stages which come into operation in an angularly displaced manner.

The at least two spring groups which are provided between the flywheel elements may be easily coupled by means of a flange body which has suitable receiving means for accommodating the individual springs. The receiving means may advantageously be formed by the flange body having radially outward cut-out portions or openings which are separated from each other in the peripheral direction by radial arms or projections and in which the springs of the first spring group are accommodated, and radially further inwardly disposed apertures in which the springs of the further spring group are disposed. The openings and the apertures, as considered in the peripheral direction, may be so arranged relative to each other that a respective aperture is disposed radially inwardly of a respective opening.The openings and the apertures may be at least approximately of the same extent in terms of angle in the peripheral direction.

In order to permit the maximum angle of rotational movement between the two flywheel elements, it may be advantageous for the first and/or the further spring groups each to have a maximum of four force storage means.

In regard to the structure and mode of operation of the apparatus, it may be particularly advantageous if radially inwardly of the annular passage the housing halves or shell-like bcdies such as shaped sheet metal members have regions which face towards each other and which form a passage for the flange body to pass therethrough. The mutually facing regions may define surfaces which are in the form of a circular ring and which define a passage or gap in the form of a circular ring, which communicates with the annular passage. In order to produce a very high damping effect by means of the viscous medium which is accommodated in the annular passage, the width of the gap may at least approximately corre spond to the thickness of the flange body.For many situations of use however it may be advantageous for the axial spacing between the mutually facing regions to be 0.1 mm to 2 mm larger than the thickness of the regions of the flange body which are accommodated therein. A part of the viscous medium accommodated in the annular passage may escape radially inwardly through the gap which is defined in that way, upon sudden relative rotary movement between the two flywheel elements. Suitable dimensioning of the gap means that the damping action caused by the viscous medium contained in the annular passage may be established at the desired level.

It is further possible for the mutually facing regions of the housing halves, and the regions of the flange body accommodated therein, to be of such a configuration relative to each other that between same there is a gap which varies in dependence on the angle of rotary movement between the flywheel elements, wherein the through-flow cross-section defined by the gap can decrease with increasing angle of rotary movement, whereby the damping action produced by the viscous medium increases.For that purpose, the flange body may be provided on at least one side with ramps which extend in the peripheral direction and which rise in the axial direction and which co-operate with counter-ramps of corresponding configuration on the region of the housing portion which is towards the flange body on that side, in such a way that when the ramps and the counter-ramps are moved towards each other, the through-flow cross-section for the viscous medium is reduced.

In regard to the structure of the apparatus, it may be particularly advantageous if the further spring group is disposed radially inwardly of the gap fdr accommodating the flange body, between the mutually facing regions of the housing halves. The housing halves or shell-like bodies may have axial recesses or indentations for accommodating that spring group. In regard to operation of the apparatus, it may be particularly advantageous in that connection for the axial recesses, the passage for accommodating the flange body and the annular passage to go into each other. To provide for satisfactpry guidance of the force storage means of the further inner spring group, it may be advantageous for the axial recesses to be adapted at least in the radially outward region to the periphery of the crosssection of the force storage means.The gap or clearance between the annular passage and the axial recesses, for receiving the flange body, may be substantially closed. For that purpose the flange body may have a region which is in the manner of a circular ring and which at least partially radially extends into the above-mentioned gap. That circular ringlike region of the flange body may advantageously be formed essentially by web portions which extend in the peripheral direction radially between the outer and inner springs and which interconnect the actuating regions of the flange body for the springs, such as radial arms or projections.

In order to facilitate assembly of the apparatus, the springs of the further spring group may be pre-curved to at least approximately the diameter at which they are arranged. That is advantageous in particular when the springs are long springs. In addition, pre-curvature of the springs of the outer and/or the inner spring groups has the advantage that they are practically free of any bending moment in the installed condition and when the apparatus is not under load.

It may be advantageous if springs of the further spring group are guided at a radially outward location by the regions which delimit the apertures in the hub body so that those springs are supported primarily against the radially outward contours of the above-mentioned apertures, when the apparatus is rotating and when it is under load, and are thus guided practically only in the axial direction by the recesses or indentations in the housing portions, which means therefore that they slide with minimum contact force along the wall delimiting the recesses in the housing portions. The outside contours of the apertures may be advantageously formed by web portions of the flange body, which are disposed between the outer and the inner springs and which extend in the peripheral direction.In order to prevent the spring ends from bearing against the housing, the individual apertures or the web portions may be extended towards the end radially somewhat inwardly so that the spring ends which are put under load, by virtue of the flange body, are retained radially by the radially outward regions of the recesses or of the annular passage.

For many situations of use however it may also be advantageous for the inner springs to be supported radially against the surfaces which define the recesses in which the springs are disposed, at least under the effect of centrifugal force. That may be advantageous in regard to springs which come into operation only after a given relative angle of rotary movement between the two flywheel elements. Furthermore, in regard to operation of the apparatus, it may be advantageous for the apertures in the flange body for the inner springs to be of such a configuration that they form noses which point in the peripheral direction and which engage directly into the ends of the springs or into a recess in an intermediate layer which is provided between a spring end and the associated actuating region of the flange body.The noses may be of such a configuration, in relation to the ends of the springs or the intermediate layers, that they hold at least the end regions of the springs radially inwardly so that when a load is applied they remain out of contact with the radially outward regions of the recesses in which the springs are accommcdated, and/or the web portions of the flange body which engage over the springs. That also gives rise to the advantages which have already been described in connection with the noses formed on the arms or projections of the flange body.

For manufacture of the apparatus, it may be particularly advantageous for the recesses for accommodating the further spring group to be annular, in other words, they extend over the entire periphery of the apparatus and the support regions in the peripheral direction for the force storage means are formed by abutment elements which are introduced into the abovementioned recesses for the further spring group. Such abutment elements may be formed by individual elements, as were described in connection with the abutment elements disposed in the annular passage. It may be particularly advantageous for the abutment elements to be formed by shaped rivets whose actuating regions for engaging the force storage means are flat or flattened off.

In regard to structure and operation of the apparatus it may be advantageous for the springs of the inner spring group to be accommodated in apertures in two discs which are rotationally connected to the other flywheel element which can be connected to the drive train, and which axially accommodate between them a flange body which couples in series the radially outward and the radially inward spring group.

In accordance with a development of the invention, it may be particularly advantageous in regard to the function and the assembly of the apparatus if the one flywheel element has the one component, which has a profile means, of an axial push-in connection, and the other flywheel element has the co-operating profile means of the push-in connection for non-rotatably coupling the two flywheel elements.Such a connection may be advantageous in particular in the case of an apparatus in which the spring groups of the damping arrangement are accommodated in a chamber which can be at least partially filled with a viscous or pasty medium and which is essen tialiy formed by the components of the one flywheel element which can be connected to the engine, and wherein the output member of the damping arrangement is a flange-like component having profiling means which can be brought into engagement with co-operating profiling means provided on the other flywheel element, and further one of the flywheel elements carries a sealing element which, when the two flywheel elements are fitted together, comes to bear sealingly against a surface of the other of the flywheel elements.Such a construction permits pre-assembly in two structural groups, namely the primary-side group which can be connected to the engine and the secondary-side group which can be connected to the drive train by way of a clutch.

It may be advantageous for the flange-like output member of the damping arrangement, such as a flange body, to have a non-rotatable coupling with the other flywheel element by way of the profiling means of the push-in connection, without being axially fixed. By virtue of such a structure, the flange can be freely aligned in the axial direction so that it is not braced between the two flywheel elements which the apparatus is assembled, whereby components of the apparatus could be subjected to an inadmissible loading and a high degree of frictional hysteresis would result, which already occurs at small angles of rotational movement and which is undesired for example when the engine is idling.It may be particularly advantageous if the flange-like output member of the damping arrangement, such as a flange body, is mounted in an axially floating condition between the two housing halves or shell-like bodies of the flywheel element which can be connected to the engine.

A particularly advantageous embodiment of the invention can be achieved in that the seal which is produced by the assembly of the two flywheel elements closes off or seals the chamber which is at least partially filled with viscous medium, relative to an annular gap which is disposed axially between the two flywheel elements which are rotatable relative to each other, wherein the annular gap may be radially outwardly open. In that connection it may be advantageous for the co-operating profile means to be provided at the outside periphery of a component which is in the form of an annular disc and which is connected to the other flywheel element.

The sealing element for sealing off the chamber advantageously has at least one sealing portion which is in the form of an annular disc. It may be advantageous for the sealing portion which is in the form of an annular disc to be axially resiliently yielding so that, after the flywheel elements have been fitted together, the sealing portion can be resiliently deformed to produce a satisfactory seal. Such a sealing portion may be carried by the flywheel element which can be connected to the engine so that, after the flywheel elements have been fitted together, the sealing portion comes to bear against a contact surface of the other flywheel element, in a prestressed condition.

To facilitate assembly of the apparatus it may be advantageous for the inside diameter of the sealing element which seals off the chamber relative to the annular passage to be larger than the outside diameter of the cooperating profiling means of the push-in connection. In that way, when the apparatus is assembled, the sealing element can be passed axially over the co-operating profiling means, which is advantageous particularly when the flange-like output member of the damping arrangement has a central opening whose peripheral contour defines the profiling means of the push-in connection and the annular disclike component which has the co-operating profile means at its outer periphery is axially fixed on a face of the other flywheel element, said face being towards the flywheel element on the engine side.

Satisfactory sealing of the chamber and a simple structure for the apparatus can be achieved in that the sealing element is axially supported with its radially outward edge region against a radial wall of the one flywheel element, which wall is formed by the housing half which adjoins the radial annular gap between the two flywheel elements. In that connection the radially outward edge region of the sealing element may be axially fixed to the radial wall. In regard to the function of the sealing element, it may be appropriate for it to be axially clamped at the outer edge region.

Such a clamping effect which may be axially resilient permits the sealing element to pivot about the region in which it is clamped in position, in a similar manner to a diaphragm spring. The contact surface for the sealing element, which is to be found on the other flywheel element, may be formed in a simple fashion by a component which is in the form of a circular ring and which is axially clamped between the face of the other flywheel element and the component having the co-operating profile means, and it extends radially outwardly further than the co-operating profiling means. That component in the form of the circular ring may be dished or displaced away from the component which is provided with the co-operating profile means, at a radially outward location.For many situations of use it may be desirable for the damping arrangement which is operative between the two flywheel elements to include at least one friction means. The friCtion means may be operative over the entire angle of rotary movement between the two flywheel elements or it may come into operation only in a given range in that angle of movement. It may be advantageous in that respect for the friction means to have at least one friction disc co-operating with at least one force storage means which is operative in the peripheral direction. The force storage means may be of such a design that the moment applied to the friction disc by the force storage means is sufficient, at least over a portion of its compression travel, to overcome the friction moment of the friction disc so that the latter is at least partially returned.It may also be desirable for the friction means disposed between the flywheel elements to have play in the peripheral direction, which means therefore that there is play between the abutments of the friction disc of the friction means, and the co-operating abutments associated therewith. That causes the point of operation of the friction means to be displaced with respect to that of the force storage means. In order to produce a frictional moment which is as constant as possible over the entire service life of the unit, it may be desirable for the friction means to be disposed in the chamber for the viscous medium, which is formed by the housing halves or shell-like bodies.

However for other situations of use it may be also advantageous for a dry friction damping means which is operative between the two flywheel elements to be additionally arranged outside the annular passage or space which is at least partially filled with viscous medium.

Although for many situations of use it may be advantageous for the friction damping means to be connected in parallel relationship with the springs of the damping arrangement, for other situations of use it may be particularly desirable to provide, between the flywheel elements, at least one friction damping means which is connected in series with the springs operative between the flywheel elements. In that connection the damping action of the friction means or friction damping means may be variable over the angle of rotary movement, wherein the damping action may increase with increasing angle of rotary movement.

In regard to function and structure of the apparatus it may be advantageous for the viscous damping and/or friction damping which is operative in parallel relationship with the inner spring group to be substantially less than the friction damping and/or viscous damping which is provided in parallel relationship with the outer spring group. Fqr that purpose outer springs may be provided at their ends with cups whose outside contour at least approximately corresponds to the contour of the annular passage, thereby providing a substantial.damping effect due to the displacement of grease. The inner springs of at least the first stage are used without spring cups in order to produce a small amount of displacement of grease and thus also a low level of damping, at least in the first stage.The springs of the inner spring group, which are fitted with play, may be installed with or without spring cups, to optimize the damping action. Furthermore the viscous damping action associated with the outer and inner spring groups may be influenced by suitably fixing the level of viscous medium. It may be advantageous for the outer annular passage to be entirely filled with viscous medium while the inner recesses accommodating the springs are only partially filled with viscous medium. Therefore the high damping action when the outer springs are compressed begins immediately with the com mencement of compression of the springs.

The damping action associated with the inner spring group on the other hand remains at a low level as the springs are only partially immersed in the viscous medium.

In regard to operation and structure of the apparatus it may be particularly advantageous for the housing half which is towards the engine, or the shell-like body which is on the engine side, to carry at a radially inward location an axial projection which is directed in the direction of the flywheel element which can be connected to the drive train, and carries a rolling bearing which mounts the two flywheel elements rotatably relative to each other. The flywheel element which can be connected to the drive train may have an axial opening into which the axial projection axially projects. In that connection it is advantageous for the opening to form a seat for accommodating the outer race of the rolling bearing.

For assembly of the apparatus, it is particularly advantageous if, prior to the two flywheel elements being connected, the rolling bearing is positively fixed to the flywheel element which can be connected to the drive train, wherein when the flywheel elements are assembled, the rolling bearing is pushed onto a seat on the axial projection.

In order to provide a multi-stage spring characteristic as between the flywheel elements, at least individual springs of a spring group or a damper may be shorter than the arcuate portion between the abutments which co-operate with those springs.

The invention will now be described in greater detail with reference to Figures 1 to 10 in which: Figure 1 is a sectional view of an apparatus according to the invention, Figure 2 is a view of the apparatus in partly broken-away form as viewed in the direction of the arrow II in Figure 1, Figure 3 is a view in section through another embodiment according to the invention, Figure 3a shows the detail indicated at "X" in Figure 6, on an enlarged scale, Figure 4 is a view in partly broken-away form of the apparatus shown in Figure 6, in the direction of the arrow IV, Figure 5 is a sectional view of half of an alternative embodiment of an apparatus according to the invention, Figure 6 is part of a sectional view taken along iine VI-VI in Figure 5, Figure 7 is a view in section taken along line VII-VII in Figure 6, also showing components which can be seen only in Figure 5, Figure 8 shows details of an apparatus according to the invention, which may be used for example in embodiments as illustrated in Figures 1 to 7, and Figures 9 and 10 show further sections through apparatuses according to the invention.

The torque transmission apparatus 1 shown in Figures 1 and 2, for compensating for rotary shocks or pulses, has a flywheel 2 which is divided into two flywheel elements 3 and 4.

The flywheel element 3 is fixed on a crankshaft 5 of an internal combustion engine (not shown in greater detail) by way of fixing screws 6. A controllable friction clutch 7 is fixed on the flywheel 4. Provided between the pressure plate 8 of the friction clutch 7 and the flywheel element 4 is a clutch disc 9 which is carried on the input shaft 10 of a transmission (not shown in greater detail). The pressure plate of the friction clutch 7 is urged towards the flywheel element 4 by a diaphragm spring 12 which is pivotaily supported on the clutch cover 11. The flywheel element 4 and thus also the flywheel 2 or the internal combustion engine can be connected to and disconnected from the transmission input shaft 10 by actuation of the clutch 7.Provided between the flywheel element 3 and the flywheel element 4 is a first radially outward damper 13 and a second radially inward damper 14 which is connected in parallel with the first damper 13. The dampers 13 and 14 permit a relative rotary movement as between the two flywheel elements 3 and 4.

The two flywheel elements 3 and 4 are mounted for relative rotation with respect to each other by way of a bearing means 15.

The bearing means 15 includes a rolling bearing in the form of a single-row bell bearing assembly 16. The outer bearing race 17 of the rolling bearing 16 is accommodated in an opening 18 in the flywheel element 4 and the inner bearing race 19 of the rolling bearing 16 is arranged on a central cylindrical trunnion 20 on the flywheel element 3, which extends axially away from the crankshaft 5 and projects into the opening 18.

The inner bearing race 19 is carried on the trunnion 20 by means of a press fit and is clamped between a shoulder 21 on the trunnion 20 or the flywheel element 3 and a securing disc 22 which is fixed on the end face of the trunnion 20.

The bearing 16 is axially secured with respect to the flywheel element 4 by the bearing 16 being clamped, with the interposition of two rings 23 and 24 of L-shaped crosssection, axially between a shoulder 25 of the flywheel element 4 and an annular disc 27 which is fixedly connected to the second flywheel element 4 by way of rivets 26.

The two rings 23 and 24 form a thermal insulation which interrupts or at least reduces the flow of heat to the bearing 16 from the friction surface 70 of the flywheel element 4, which co-operates with the clutch disc 9.

The radially inwardly directed legs 23a and 24a of the rings 23, 24 partially extend radially over the inner bearing race 19 and bear axially thereagainst whereby they serve at the same time as a seal for the bearing 16. In order to ensure a satisfactory sealing effect for the bearing 16, the radially extending legs 23a and 24a are each urged axially towards the end faces of the inner bearing race 19 by a respective force storage means in the form of diaphragm springs 28 and 29.

The flywheel element 3 forms a housing which delimits an annular chamber 30 in which the dampers 13 and 14 are accommodated. The flywheel element 3 which has the annular chamber 30 substantially comprises two housing portions 31 and 32 which are connected together at a radially outward location by means of screws 33. The screws 33 are provided in the radial region of the end faces or contact faces 34 and 35, by way of which the two housing halves 31 and 32 bear against each other. The faces 34 and 35 are disposed radially outwardly of the first damper 13.

To seal off the annular chamber 30 in an outward direction the arrangement includes a sealing ring 36 which is arranged axially between the two faces 34 and 35 and radially inwardly of the screws 33. The housing portion 31 has an axial annular groove 37 to accommodate the sealing ring 36. For precise positioning of the two housing portions 31 and 32 in the assembly operation, the arrangement also includes cylindrical pins 38 which are accommodated radially outwardly of the sealing ring 36 in axially aligned bores in the two housing portions 31 and 32.

At the outer periphery the housing portion 31 which is towards the engine has a shoulder 39 on which a toothed starter ring 40 is a shrink fit. The two housing portions 31 and 32 may be made from cast iron. If a low moment of inertia of the first flywheel element 3 is desired, then at least one of the housing portions 31 and 32 may be made from a light metal alloy such as cast aluminium. Such light metal or alloy cast components have the advantage that they can be produced by a pressure or pressing process and can be used without major finishing operations.

The two dampers 13 and 14 have a common output member in the form of a radial flange 41 which is arranged axially between the two housing portions 31 and 32. As can be seen in particular from Figure 2, the flange 41 is non-rotatably connected with its radially inward regions by way of an axial push-in connection 42 to the annular disc portion 27 which is fixed on the end face of the axial projection 43, facing in the direction of the crankshaft 5, of the flywheel element 4, by way of rivets 26. For precise radial positioning in the assembly operation, a centering seat 43a is provided between the annular disc portion 27 and the axial projection 43.

At its outside periphery the flange 41 has radial arms or projections 44 which form the actuation regions for the force storage means in the form of coil springs 45 of the outer damper 13. Radially inwardly of the openings or recesses 46 which, as considered in the peripheral direction, occur between the projections 44, for accommodating the coil springs 45, the flange 41 has arcuate apertures 47 in which the force storage means in the form of coil springs 48 of the inner damper 14 are accommodated. Radially between the openings 46 and the apertures 47, the flange 41 forms web portions 49 which extend in the peripheral direction and which interconnect the radial projections 44 and the radial regions of the flange 41, which are present between the apertures 47 in the peripheral direction. The radial regions 50 form the actuation regions of the flange 41 for the coil springs 48.

At a radially outward location the annular chamber 30 forms a receiving means 51 which is in the nature of an annular passage or of a torus-like configuration and into which the projections 44 of the flange 41 radially engage.

The annular passage-like receiving means 51 for the force storage means 45 is essentially formed by axial recesses or indentations 52 and 53 which extend over the periphery of the assembly and which are provided in the radial regions of the housing portions 31 and 32 and into which the regions of the force storage means 45, which project on both sides of the flange 41, axially engage. The annular passage-like receiving means 51 is closed in the radially inward direction by the web portions 49 of the flange 41, apart from a narrow gap 54.

As can be seen from Figure 1, the axial recesses 52 and 53 are of such a cross-sectional configuration that the arcuate path thereof is at least approximately matched to the periphery of the cross-section of the force storage means. The outer regions of the recesses 52 and 53 can thus form for the force storage means 45 contact or guide regions against which the force storage means 45 can be radially supported, at least under the effect of centrifugal force. By virtue of the contact regions formed by the recesses 52 and 53 being matched to the outside periphery of the force storage means 45, the wear which occurs due to the friction of the turns of the force storage means against the radially outward regions of the recesses 52 and 53 can be substantially reduced as the support area as between the springs 45 and the recesses 52 and 53 is enlarged.

To provide for actuation of the force storage means, peripheral abutments 55 and 55a are disposed in the recesses 52 and 53 on both sides of the projections or arms 44. In the illustrated embodiment, the peripheral abutments 55 and 55a, as considered in the peripheral direction, are of the same angular extent as the arms 44 of the flange 41. The abutments 55 and 55a are formed by compo nents 56 and 57 which are adapted to the recesses 52 and 53 and which are fixedly connected to the housing portions 31 and 32 by means of rivets 58. The end regions of the abutments 55 and 55a, as considered in the peripheral direction, are flattened off for improved actuation of the force storage means 45.

Provided between the projections 44 and the ends of the springs 45 which are theretowards are spring cups 59 (see Figure 2), the periphery of which is matched to the crosssection of the receiving means 51.

Radially inwardly of the annular passage-like receiving means 51 the housing halves 31 and 32 have regions 60 and 61 which face towards each other and which form annular surfaces and between which there is an annular passage 62 for the flange 41 to pass therethrough.

In the embodiment shown in Figures 1 and 2 the width of the passage 62 is somewhat greater than the regions of the flange 41 which are contained therein so that there is a gap 54 at least on one side of the flange 41.

Radially inwardly of the passage 62, the housing portions or housing halves 31 and 32 have further axial recesses 63 and 64 into which the regions of the inner coil springs 48, which regions project beyond the flange on both sides thereof, are at least partially engaged.

As can be seen from Figure 1, the axial recesses 63 and 64 are of a cross-sectional configuration such that the arcuate path thereof is matched at least in the radially outward region to the periphery of the crosssection of the coil springs 48 so that the springs 48 are held or guided at least in the axial direction by the recesses 63 and 64.

In a similar manner to the outer recesses 52 and 53, the inner recesses 63 and 64 also extend over the entire periphery of the apparatus. That is advantageous as in that case for example the pre-cast recesses 52, 53 and 63, 64 can be machined in one turning operation.

For actuation of the force storage means or coil springs 48, peripheral abutments 65 and 66 are introduced into the recesses 63 and 64, with those abutments forming support regions for the coil springs 48, in the peripheral direction. The abutments 65 and 66 are formed by components which are adapted to the recesses 63 and 64 and which are fixedly connected to the housing portions 31 and 32 by way of rivets 67. As can be seen from Figure 2, the abutments 65 and 66 which are disposed on both sides of the radial regions 50 of the flange 41 are of a smaller angular extent, as considered in the peripheral direction, than the radial regions 50 which actuate the coil springs 48.

The web portions 49 of the flange 41 are so dimensioned relative to the inner recesses 63 and 64 that the coil springs 48 bear radially against the web portions 49 at least under the effect of centrifugal force.

That is advantageous as the flange can be made from steel which is at least surfacehardened whereby the wear at the radial support regions for the springs 48 can be reduced. A further advantage of the radial support for the springs 48 against the web portions 49 is that, until the springs 48 bear against the abutments 65 and 66, the springs 48 can rotate with the flange 41 without giving rise to substantial friction as a result of the centrifugal force acting thereon, against the housing portions 31 and 32. In many cases such friction is undesirable as it falsifies the characteristic of the outer damper 13.

As can be seen from Figure 2, as viewed over the periphery of the apparatus 1 there are in each case three springs 45 and 48, with the radially outward springs 45 each extending at least approximately over an angle of 110 degrees. The radially inward springs 48 extend at least approximately over the same angle as the outer springs 45. In the present case a spring 48 extends at least approximately over 100 degrees. The outer springs 45 therefore extend over around 91% of the periphery of the apparatus while the inner springs 48 extend over around 83% of the periphery.

In their condition when not fitted into position, the springs 45 and/or the springs 48 may be straight, as considered in the axial direction, which means therefore that, when those springs are fitted into place, the springs must be bent to correspond to the shape of the recesses which accommodate them, or the springs 45 and/or the springs 48 may already be of a suitably curved configuration corresponding to the shape of the recesses which accommodate them. The use of precurved springs 45 and 48 makes it possible to reduce the stresses which occur therein when they are compressed, while further facilitating the assembly operation.

Provided in the annular chamber 30 is a viscous medium or a lubricant such as for example silicone oil or grease. The level of the viscous medium or lubricant may extend at least as far as the middle region or the axis of the outer springs 45 of the damper 13, when the apparatus 1 is rotating. In the illustrated embodiment it is advantageous for that level to reach at least as far as the outer regions of the turns of the inner coil springs 48 so that wear-reducing lubricant is provided at least between those turns and the regions which radially support them, being in the present case the web portions 49 of the flange 1. In the case of the illustrated apparatus 1, it is advantageous for the filling of viscous medium or lubricant to extend approximately as far as the axis of the inner coil springs 48.

The association of the annular chamber 30 which contains a viscous medium or lubricant, with the flywheel element 3 which is connected to the engine, and the spatial separation from the flywheel element 4 which carries the friction clutch 7, substantially prevents the heat which is generated in connection with the friction clutch from having an influence on the viscous medium or lubricant.

Furthermore, provided between the annular chamber 30 or the housing portion 32, and the flywheel element 4, is an outwardly open annular passage 68 which further improves the cooling action, in conjunction with ventilation passages 69. The air passages 69 are disposed radially inwardly of the friction surface 70 of the flywheel element 4 for the clutch disc 9.

As can be seen in particular from Figure 2, the flange 41 has a central opening 71 whose contour forms radial profiling means 72 which are in engagement with co-operating profiling means 73 provided at the outside periphery of the annular disc member 27 which is connected to the flywheel element 4. The profiling means 72 and the co-operating profiling means 73, which form the axial push-in connection 42, permit satisfactory alignment of the flange 41 between the two housing halves 31 and 32 so that the gap 54 between the passage 62 and the flange 41 can be very small. The connection 42 also permits the axial tolerances between the various contact and support surfaces of the components to be enlarged.

To seal off the annular chamber 30, a seal 74 is disposed between the radially inward region of the housing portion 32 and the annular disc 27 or the axial projection 43 on the flywheel element 4. The seal 74 comprises an annular disc 75 which bears with its radially inward region against a shoulder 76 formed on the axial projection 43 and with its outer region against a surface 77 which is formed on the radially inward region of the annular housing portion 32. The annular disc 75 is axially deformable similarly to a diaphragm spring. The annular disc 75 is urged axially towards the shoulder 76 and the surface 77 by a diaphragm spring 78 which is axially braced between the disc 75 and the flange 41.The diaphragm spring 78 also urges the flange 41 towards the surface 60 whereby a gap 54 is to be found between the annular passage-like receiving means 51 at the radially further inwardly disposed regions of the annular chamber 30, only on one side of the flange 41. As can be seen from Figure 1, the seal 74 seals off the annular chamber 30 relative to the annular gap 68 between the two flywheel elements 3 and 4. The inside diameter of the disc 75 which seals off the annular chamber 30 relative to the annular gap 68 is larger than the outside diameter of the co-operating profiling means 73 of the connection 42.

The connection 42 and the seal 74 permit the torque transmission apparatus 1 to be assembled in a particularly simple manner, in that firstly the two flywheel elements 3 and 4 are pre-assembled and thereafter are axially connected together by being axially fitted together and by the securing disc 22 being fixed on the end of the projection 20. For that purpose the seal 74 is firstly pre-assembled on the flywheel element 3 and the rolling bearing 16 is positively fixed on the flywheel element 4. When the two flywheel elements 3 and 4 are assembled the inner rolling bearing race 19 is pushed onto the seat 20a on the axial projection 20 on the housing portion 31 and the co-operating profiling means 73 are brought into engagement with the profiling means 72.In addition, while the two flywheel elements 3 and 4 are being fitted together, the radially inward region of the sealing disc 75 comes to bear against the co-operating sealing surface which is formed by the shoulder 76 so that the sealing disc 75 is pivoted in itself against the force of the diaphragm spring 78 and bears in a prestressed condition against the shoulder 76. As already mentioned, the two flywheel elements 3 and 4 are axially fixed together in their definitive position relative to each other by fixing the disc 22 to the projection 20.

In order to reduce the wear in the contact region between the turns of the springs 45 and 48 and the recesses 52, 53 and 63, 63 respectively associated therewith, at least in the contact regions the surfaces of the portions 31 and 32 which define said recesses may have a higher level of hardness. That can be effected for example by the contact regions being subjected to inductive hardening, case hardening, laser beam hardening or flame hardening. When dealing with very high levels of loading however it may also be advantageous for the portions 31 and 32 which define the above-mentioned recesses to have a coating for reducing abrasion wear, at least in the above-mentioned contact regions. Such a coating may be formed for example by chemical nickel plating, chromium plating or by coating with plastics material or molybdenum.

The coating applied may also be subsequently smoothed in order to give a better surface quality for the recesses against which the turns of the springs rub. Such a smoothing operation may be carried out for example by means of a grinding process or a turning machining operation.

The mode of operation of the apparatus shown in Figures 1 and 2 will now be described.

When the flywheel element 4 rotates relative to the flywheel element 3 from the rest position shown in Figure 2, the flange 41 is driven by way of the connection 42 so that firstly the outer springs 45 are compressed between the peripheral abutments 55 and 55a and the radial projections 44. After the angle of relative rotary movement has been covered in one direction of rotation, as indicated at 79, or in the other direction of rotation, as indicated at 80, the peripheral abutments 65 and 66 come to bear against the inner springs 48 so that the springs 48 are compressed, in addition to the springs 45, upon a further relative rotary movement between the two flywheel elements 3 and 4. Joint compression of the springs 45 and 48 occurs until the inner springs 48 become blocked whereby the relative rotary movement between the two flywheel elements 3 and 4 is restricted.In the illustrated embodiment the maximum angle of rotary movement, starting from the rest position shown in Figure 2, in both directions of rotation, is of the order of magnitude of 47 degrees. Upon a relative rotary movement occurring between the two flywheel elements 3 and 4, a frictional damping effect is produced by the outer springs 45 rubbing against the surfaces of the recesses 52 and 53 and by the flange 41 rubbing against the surface 60.

A friction damping action also occurs between the radially inward springs 48 and the radial support regions thereof. The friction damping effect which occurs between the springs 45, 48- and the radial support regions thereof is dependent on speed of rotation, with the damping effect increasing with increasing speed of rotation. A damping action is also produced by turbulence in or displacement of the viscous or pasty medium contained in the annular chamber 30. In particular the viscous medium which is present in the practically closed annular passage-like receiving means 31 produces a hydraulic or viscous damping action as the spring cups 59 are operative in a piston-like manner in the passage-like receiving means 51.When the outer springs are compressed, the spring cups 59 which are acted upon by the arms 44- are moved in the direction of the cups which bear against the peripheral abutments 55 and 55a so that the viscous medium present in the springs is substantially displaced through the gap 54 which acts in a similar manner to a throttle means.

A further part of the viscous medium is displaced between the spring cups 59 and the walls of the passage-like receiving means 51.

The viscous medium which is initially displaced inwardly is uniformly distributed over the periphery of the arrangement again, as a result of the centrifugal force acting on the medium. While the outer springs 45 are relieved of load, the viscous medium which is to be found on the side of the spring cups 59 which is remote from the springs 45 is pressed past the spring cups in a similar manner and urged through the gap 54 and fills the springs 55 again, as a result of the centrifugal force acting on it. The damping action -pro- duced by the viscous medium is dependent on the centrifugal force which acts on the me-: dium, in other words, the damping action increases with increasing speeds of rotation.

The regions of the radially inward springs 48 which dip into the viscous medium also produce a viscous or hydraulic damping effect, -due to turbulence.

The damping action produced by the viscous medium may be varied or adapted to the respective situation of use by virtue of the provision of axial openings or cut-out portions in at least some cups and by suitable dimensioning of the gap 54 and the outside periphery of the cups. The viscous or hydraulic damping action may also be adapted by only some of the springs 45 being provided with cups 59. Spring cups may also be disposed between the ends of at least one inner spring 48 and the radial regions 50 of the flange 41.

The apparatus shown in Figures 3 and 4 has two flywheel elements 3 and 4 which are mounted rotatably relative to each other by way of a rolling bearing 16 in a similar manner to the apparatus shown in Figures 1 and 2. The disc 122 for axially securing the two flywheel elements is fixed on the end of the axial projection 120 by means of rivets 122a.

The two flywheel elements 3 and 4 are assembled in a similar manner to that described with reference to Figures 1 and 2. That means that the bearing 16 is firstly premounted on the flywheel element 4 and is pushed onto the seat 120a on the axial projection 120, when the two flywheel elements 3 and 4 are assembled. In addition, a seal 174 is pre-mounted on the flywheel element 3 which is on the engine side, prior to the two flywheel elements 3 and 4 being assembled, and an axial push-in connection 142 is provided between the flange 141 forming the output member of the two dampers 13 and 14 which are connected irl parallel relationship, and the disc-like component 127 which is fixed to the flywheel element 4 by way of rivets 126. The two housing portions 131 and 132 which delimit the annular chamber 130 are in the form of cast components.At its periphery-the housing portion 132 has an axial cylindrical projection 132a, by way of the inward peripheral surface 135 of which the housing portion 132 is centered on an outer peripheral surface 134 of the housing portion 131. The two cast housing portions 131 and 132 are axially secured by way of radial pins 138 which are disposed in the region of the centering surfaces 134 and 135. The housing portion 132 carries a toothed starter ring 140 which partially engages axially over the pins 138 so that-the latter cannot escape radially.

The axial connection 142 is formed by radial arms or projections 172 which are formed at the inside periphery of the flange 141 and which engage between radial projections 173 formed on the outside periphery of the disclike component 127.

As can be seen in particular from Figure 3a, the seal 174 which is disposed between the radially inward region of the housing portion 132 and the disc-like component 127 or the axial projection 143 on the flywheel element 4 comprises an axially resilient disc 175 of circular ring-like configuration and which bears with its radially inward region against an annular component 176 secured to the axial projection 143, and is axially fixed with its radially outward region to the radially inward region of the housing portion 132. At its radially outward and inward regions the sealing disc 175 which is axially deformable in a similar manner to a diaphragm spring carries a coating 175a, 175b such as a plastics ccating which is applied for example by being sprayed thereon.The coatings 175a and 175b are to have a low coefficient of friction and a certain degree of elastic or plastic deformability. The radially outward edge region of the sealing disc 175 is sealingly fixed in an annular carrier 180 by a flange-like connection. The outer region of the sealing disc 175 is fixed in position in that way in such a manner that the sealing disc 175 can undergo a variation in its conicity. The regions 180b of the annular carrier 180 which engage around the outer periphery of the sealimg disc 175 are accommodated in an axial recess or axial groove 1 77 formed at the radially inward region of the housing portion 132.For the purposes of axially fixing the outer region of the sealing disc 175, the annular carrier 180 has regions 180a which are flanged over, engaging radially around the inward edge 132b of the housing portion 132. The annular carrier 180 forms a pivotal mounting of a circular ring-like configuration for the sealing disc 175 which is deformable in a similar manner to a diaphragm spring.

The annular component 176 which has a sealing surface co-operating with the sealing disc 175 has a radially inward disc-like region 1 76a which is axially clamped between the end face of the axial projection 143 and the disc-like component 127, and a circular ringlike outer region 176b against which the sealing disc 175 sealingly bears in an axially prestressed condition. The radially outward regions 176b of the annular component 176 are set back in the axial direction, with respect to the radially inward regions 176a, from the disclike component which carries the co-operating profiling means 173 of the connection 142.

As can be seen from Figure 3, the seal 174 seals off the annular chamber 130 relative to the annular gap 168 between the two flywheel elements 3 and 4.

In order to permit the two flywheel elements 3 and 4 to be axially fitted together, the inside diameter of the sealing disc 175 is larger than the outside diameter of the radial projections or co-operating profiling means 173. The regions 176b of the annular component 176, against which the sealing disc 175 is axially supported, extend radially outwardly further than the co-operating profiling means 173.

When the rolling bearing 16 is pushed onto the seat 120a, the connection 142 is made and the sealing disc 175 is axially braced by virtue of bearing against the co-operating sealing regions 176b.

In order to prevent or reduce wear at the radial support regions of the passage-like receiving means 151 for the springs 145, the arrangement includes a steel strip or band 181 which has a high level of hardness and which extends over the periphery of the passage-like receiving means 151 and embraces the springs 145. The steel band 181 is cylindrical and is accommodated in a recess 182 formed by a radial groove or a radial slot.

When the apparatus 101 is rotating the springs 145 bear against the steel band 181 by way of their turns, as a result of the centrifugal force acting thereon.

The peripheral abutments 155 and 1 55a for the outer springs 145 and the peripheral abutments 165 and 166 for the inner springs 148 are formed by shaped members such as forged or pressed members which have rivets 158 and 167 formed integrally thereon, for fixing to the respective housing portions 131 and 132.

As can be seen from Figure 4, the abutments 155 and 1 55a which are provided on both sides of a projection 144 of the flange 141 are of a greater extent in the peripheral direction than the projections 144, while in the illustrated embodiment, in the rest position of the apparatus as shown in Figure 4, the projections 144 are arranged centrally with respect to the abutments 155 and 155a, in other words, the abutments 155 and 155a project beyond the projections 144 by the same amount on both sides.

The peripheral abutments 165 and 166 which are arranged on both sides of the radial regions 150 of the flange 141 are also of a greater extent in the peripheral direction than the regions 150 which serve for actuation of the springs 148. However the arrangement of the abutments 165 and 166 with respect to the radial regions 150 is such that in the rest position of the apparatus 101 the peripheral abutments 165 and 166 project on one side with respect to the regions 150 whereas on the other side the abutments 165 and 166 and the radial regions 150 may be flush. Furthermore the displacement of the abutments 165 and 166 with respect to the radial regions 150 is such that two peripherally successive abutments 165 and 166 are displaced in opposite directions of rotation relative to the radial regions 150 of the flange 141, which are associated therewith.As a result of that structure the inner springs 148 form two spring groups, namely 148a and 148b, which come into operation in a step-wise manner.

When the apparatus 101 is rotating, the vis cous medium or lubricant such as for example silicone oil or grease which is accommodated in the annular chamber 130 should fill at least the passage-like receiving means 151. It may be advantageous however for the level of the viscous medium or lubricant to reach at least as far as the outer regions of the turns of the inner coil springs 148, in which respect it may be particularly desirable for the filling of viscous medium or lubricant to extend approximately as far as the axis of the inner coil springs 148.

Disposed between the projections 144 or the peripheral abutments 155 and 155a and the associated ends of the springs 145 are spring cups 159 whose periphery is matched to the cross-section of the passage-like receiving means 151. That produces a comparatively high damping effect due to displacement of the viscous medium present in the annular chamber 130, as described with reference to Figures 1 and 2.

The spring cups 159 have a slightly tapering projection 1 59a which extends axially into the respective springs 145. In the illustrated embodiment the end 159b of the projection 1 59a is of a conical configuration, but it could also be of a part-spherical shape. Such a configuration for the spring cups 159 ensures that, if a cup slips out of the end of the spring in operation of the arrangement, when the cup is put under load again or when the spring is relieved of stress, the cup is automatically re-engaged into the spring so that the spring or the cup do not suffer damage.

Spring cups 159 can come out when the outer springs 145 are compressed and the apparatus 101 is rotating at a comparatively high speed. In that operating condition the friction between the turns of the springs 145 and the radial support regions of the housing portions 131 and 132 for the springs may be so high that, in the event of an abrupt shock reversal of load, the springs 145 cannot be at least fully relieved of stress. Spring cups 159 can be urged out of the ends of the springs 145 which are not relieved by virtue of displacement of viscous medium which is caused by the radial projections 144 during the shock reversal of load, the viscous medium being distributed again at an outward location under the effect of centrifugal force.

The mode of operation of the apparatus shown in Figures 3 and 4 will now be described.

When the flywheel element 4 rotates relative to the flywheel element 3 from the rest position shown in Figure 4, the flange 141 is driven by way of the connection 142 so that firstly the inner springs 148b are compressed between the peripheral abutments 165, 166 and the radial regions 150. After the angle of relative rotary movement has been covered in one direction, as indicated at 179, or in the other direction, as indicated at 190, the radial regions 150 of the flange 141 come to bear against the ends of the inner springs 148a so that the springs 148a and 148b are jointly compressed upon further relative rotary movement as between the two flywheel elements 3 and 4.After the angle of relative rotary movement has been covered in one direction of rotation, as indicated at 179a, or in the other direction, as indicated at 190a, the outer springs 145 are actuated by the radial projections 144 so that the springs are compressed between the peripheral abutments 155 and 155a and the radial projections 144 upon further relative rotary movement. In the illustrated embodiment the angle 179 corresponds to the angle 179a and the angle 190 corresponds to the angle 190a so that the springs 148a and the springs 145 are operative simultaneously. In the illustrated embodiment as shown in Figures 3 and 4, that therefore gives a two-stage spring characteristic.However the angles 179 190, 179a and 190a may also be only partly of the same amount or may be of different values so that it is possible to have an at least three-stage spring characteristic in both directions of rotation or an at least two stage- spring characteristic in one direction of rotation and an at least three-stage spring characteristic in the other direction.

In addition, as indicated in broken lines at 1 65a in Figure 4, the peripheral abutments 165 and 166 may be set back with respect to the ends of the springs 148b which are retained in the flange, so that in that case there is no springing action about the zero position in respect of the relative rotary movement between the two flywheel elements 3 and 4 over a given angle, and only a hydraulic or viscous damping action and/or a friction damping action takes place.

The level or the characteristic of the hydraulic or viscous damping action may be varied by for example providing only some of the outer springs 145 with spring cups 159 or by providing no cup 159 at one end of at least one spring 145. In addition at least one spring 148a and/or 148b may be provided with spring cups. Further factors which affect the viscous or hydraulic damping action are the radial filling height of viscous medium as well as the width of the gap or gaps between the flange 141 and the surfaces 160 and 161 of the housing portions 131 and 132.

The hydraulic or viscous damping action due to turbulence in or displacement of the viscous medium takes place in a similar manner to that described with reference to Figures 1 and 2.

As can be seen from Figure 4, provided over the periphery of the apparatus 101 are four springs 145 and 148 respectively, with the radially outward springs 145 each extending at least approximately over 78 degrees.

The radially inward springs 148b extend at least approximately over an angle of 74 de grees of the periphery and the springs 148a extend at least approximately over an angle of 68 degrees. That means that the outer springs 145 extend at least approximately over 86% of the periphery whereas the inner springs 148 extend at least approximately over 79% of the periphery.

As can be seen in particular from Figure 4, the component 3a of the flywheel element 3 is provided at the outside periphery with radial arms or projections 186, in each of which there is provided a respective screw-threaded bore 187 for fixing the friction clutch in position. Some of the projections 186 have bores 188 for accommodating pins which ensure that the clutch cover is accurately positioned on the component 3a in the assembly operation.

The radial projections 186 permit the flywheel element 3 to be of a lighter construction. Furthermore, the radial recesses 186a between the radial projections 186 provide a better cooling action for the component 3a and the clutch mounted thereon as air can circulate between the cover and the recesses 186a. Disposed radially inwardly of the friction surface 4a of the component 3a are ventilation passages 169 which communicate with the radial gap 168 between the two flywheel elements 3 and 4.

The radial projections 186 further permit the component 3a to be thicker in the region of the friction surface 4a, when of a pre-determined weight, so that it is possible to avoid overheating in that region.

A variation in the damping action produced by the viscous medium can further be achieved by the passage-like receiving means 151 not being of a constant cross-section at least over portions of the longitudinal extent of at least one spring 145 so that a lower damping effect is generated in the regions of larger cross-section.and a greater damping effect is produced in the regions of smaller cross-section. Although that variation in crosssection of the passage-like receiving means 151 may be provided at any desired location or even at a plurality of locations, it is particularly desirable for such variations or increases in cross-section to be in the end regions of the springs 145 in the non-compressed condition. In that connection the variations in crosssection may be abrupt or progressive.It is particularly advantageous for the increase in cross-section to be in the region of the radially inward half of the passage-like receiving means 151. Such an increase in cross-section is shown in Figure 4 and identified by reference numeral 189. The enlargement 189 is formed on the flange 141 which closes or defines the passage-like receiving means 151 in a radially inward direction. However the enlargements may also be formed by suitable shaping of the recesses 152 and 153 which delimit the passage-like receiving means 151.

The torque transmission apparatus 201 shown in Figures 5 and 6, for compensating for rotary shocks or pulses, comprises a flywheel 202 which is divided into two flywheel elements 203 and 204. The two flywheel elements 203 and 204 are mounted rotatably relative to each other by way of a bearing means 15. The flywheel element 203 forms a housing which defines an annular chamber 230 in which a damping arrangement 213 is accommodated.

The flywheel element 203 which comprises the annular chamber 230 essentially consists of two housing portions 231 and 232 which are connected together at a radially outward location. The two housing portions 231 and 232 are formed by shaped sheet metal members which are joined together at their outward periphery by welding at 238. The welding 238 simultaneously closes off the annular chamber 230 in a radially outward direction.

Resistance butt welding or capacitor percussion welding is advantageously suitable for welding the two members 231 and 232 together, that is to say a welding operation in which the regions of two components which are in contact and which are to be welded together are heated to welding temperature by applying an alternating current of high current strength and low voltage to the components, and joined together under pressure.

To carry out such a welding operation, the two shell-like sheet metal members 231 and 232 have end regions or butt surfaces 234 and 235 which are of a defined area in relation to the current strength used for the welding operation. The housing portions 231 and 232 lie axially against each other and are or become welded together in the region of those surfaces 234 and 235.

For the purposes of accurate radial positioning of the two housing portions 231 and 232 during the welding operation, the housing portion 231 is provided at a radially outward location with an annular projection 231a which engages around a centering surface 235a which is formed on the outside periphery of the housing portion 232. Axial recesses or countersinks 265 and 266 are provided in the housing portions 231 and 232 for precise positioning in the peripheral direction during the welding operation. Pins of the welding apparatus can engage into the recesses 265 and 266, to hold the two housing portions 231 and 232 in a precise angular position relative to each other during the welding operation.

As, during the operation of welding the two sheet metal shell portions 231 and 232, as the result of the formation of the welded seam, there is a certain amount of axial movement during the sheet metal shell portions, it may advantageous to provide axial abutments between the shell portions, which abutments come into operation only during the welding operation. Figure 5 shows in dash-dotted lines an abutment of that nature which is formed on the sheet metal shell portions 232, being identified by reference numeral 267.The use of such limiting abutments 267 means that the operator is not so dependent on the current strength used for the welding- operation, in other words it is also possible to operate with a higher current strength as the axial position of the two housing portions 231 and 232 is determined by the abutments 267 and not by the current strength and the axial pressure applied to the two housing portions 231 and 232 during the welding operation.

The output member of the damper 213 is formed by a radial flange 241 disposed axially between the two housing portions 231 and 232. The flange 241 is fixed with its radially inward regions by way of an annular push-in connection 242 to the annular disc member 227 which is fixed by way of rivets 226 to the end of the axial projection 243 on the flywheel element 204, the projection 243 facing towards the housing portion 231 which is on the engine side.

At its outer periphery the flange 241 has radial arms or projections 244 which form the actuation regions for the force storage means in the form of coil springs 245 of the damper 213.

At a radially outward location the two housing portions 231 and 232 form a receiving means 251 which is in the form of an annular passage or which is of a torus-like configura tiOn. The radial projections 244 on the flange 241 engage into the receiving means 251.

The receiving means 251 for the force storage means 245 is essentially formed by axial recesses or indentations 252 and 253 which extend over the periphery of the arrangement and which are provided in the housing portions 231, 232 made of sheet metal. The regions of the force storage means 245 which project on both sides- of the flange 241 axially engage into the recesses 252 and 253. The receiving means 251 is closed radially inwardly by an annular region 249 of the flange 241, except for a small gap 254.

As can be seen from Figure 5, the axial recesses 252 and 253 are of such a crosssection that the arcuate configuration thereof is at least approximately matched to the periphery of the cross-section of the force storage means 245. The outer regions of the recesses 252 and 253 can thus form contact or guide regions for the force storage means 245. The force storage means 245 can thus be radially supported against the contact or guide regions, at least under the effect of centrifugal force.

Peripheral abutments 255 and 255a are provided in the recesses 252 and 253 on both sides of the projections 244, for actuation of the force storage means 245. In the illustrated embodiment the abutments 255 and 255a are of the same extent, as considered in the peripheral direction, as the radial projections 244 on the flange 241. As can be seen from Figure 6, provided between the projections 244 and the associated ends of the springs 245 are intermediate members in the form of spring cups 259 whose periphery is matched to the cross-section of the passage-like receiving means 251.

Radially inwardly of the receiving means 251 the housing portions 231 and 232 have regions 260 and 261 which face towards each other and form surfaces of a circular ring-like configuration. A passage 262 in the form of a circular ring for receiving the flange 241 is to be found between the regions 260 and 261.

In the illustrated embodiment shown in Figures 5 and 6, the width of the passage 262 is only slightly greater than the regions of the flange 241 which are accommodated therein, so that there is a very small gap 254.

As can be seen frcm Figure 6, there are four springs 245, as viewed over the periphery of the apparatus 201, which springs each extend at least approximately over an angle of 82 degrees of the periphery. That means that the springs extend over at least approximately 90% of the periphery of the apparatus 201.

In order to reducethe stresses which occur in the springs 245 when they are compressed and to facilitate assembly, the springs 245 are at least approximately pre-curved to the radius on which they are arranged.

A viscous medium or a lubricant is provided in the annular passage 203. In that connection, the viscous medium should fill at least the receiving means 251, when the apparatus 201 is rotating.

As can be seen from Figure 6, the flange 241 has a central opening 271 whose contour forms radial profiling means 272 which are engaged with co-operating profiling means 273 provided at the outer periphery of the annular disc member 227 which is connected to the flywheel element 4. The co-operating profiling means 273 are formed by radial projections which engage into correspondingly matched recesses 272a in the flange 241.

Also provided in the region of the radial projections 273 are the rivets 226 which fix the member 227 to the flywheel element 204.

The configurations 272 and 273 which form the axial push-in connection 242 permit the flange to be satisfactorily aligned between the two housing portions 231 and 232 so that the gap 254 between the passage 262 and the flange 241 can be very small.

The connection 242 also permits the axial tolerances between the various contact and support surfaces of the components to be enlarged.

A seal 274 is provided between the radially inward region of the housing portion 232 and the flywheel element 204, to seal off the annular chamber 230. The seal 274 is essen tially distinguished from the seal 174 described with reference to Figure 6 in that the annular axially resilient disc 275 is completely covered and is axially clamped at a radially outward location between an annular region 232a of the housing portion 232 and an annular disc 280 which is fixed to the housing portion 232 by means of rivet connections 232b.

The annular region 232a of the housing portion 232 extends radially inwardly from the outside diameter of the resilient sealing disc 275, with a radial space 232c being formed between the annular region 232a and the sealing disc 275. The small amounts of viscous medium which may possibly escape between the inner region of the sealing disc 275 and the co-operating sealing regions 276b can be caught in the radially inwardly open radial space 232c and, at higher speeds of rotation, under the effect of centrifugal force, can be urged back into the annular- chamber 230 between the annular region 232a and the sealing disc 275. The contact zones between the inner regions of the sealing disc 275 and the co-operating sealing regions 276b are provided in the region in which the radial space 232c axially extends.

Formed on the inner region of the housing portion 232 is an axial recess or step 291 whose radially outward peripheral surface axially engages over the outer regions of the sealing disc 275.

At an inward location the housing portion 231 which is towards the engine carries an axial projection 220 on which the rolling bearing 16 which mounts the two flywheel elements 203 and 204 relative to each other is carried in a similar manner to that described with reference to Figure 1. The sheet metal portion 231 is centered on a seat 220b on the projection 220 and bears axially against a radial surface 220c, which is provided adjoining the seat 220b, on the projection 220.

The connection between the sheet metal member housing portion 231 and the axial projection 220 may be made by screwing, riveting, welding or peening.

The two flywheel elements 203 and 204 are assembled in a similar manner to that described with reference to Figures 1 and 2, that is to say, the rolling bearing 16 is firstly pre-mounted on the flywheel element 204 and the sealing disc 275 is pre-mounted on the flywheel element 203. When the bearing 16 is pushed onto the seat 220a on the projection 220 the connection 242 is made and the sealing disc 275 is axially braced by bearing against the co-operating sealing regions 276b on the flywheel element 204. The two flywheel elements 203 and 204 are axially secured together by the securing disc 222 which radially overlaps the inner bearing race of the bearing 1-6 being fixed on the end of the projection 220. The disc 222 may be fixed in position by riveting, similarly as illustrated in Figure 6. It is also possible however to use screws instead of rivets.

The hydraulic or viscous damping effect due to displacement of or turbulence in the viscous medium in the passage-like receiving means 251 is produced in a similar manner as described with reference to Figures 1 and 2.

In order to ensure that, when the two sheet metal housing portions 231 and 232 are welded, the components which are in contact therewith, such as in particular the movable components, do not become locally welded to the housing portions or experience a change in structure as a result of local overheating, electrical insulation is provided between those components and the sheet metal housing portions 231 and 232. The components which are put at risk during the welding operation are in particular the springs 245 in the passage-like receiving means 251, the flange 241 and the spring cups 259.

The insulating covering may be provided on the housing portions 231, 232 and/or on the components 245, 241, 259, 255 and 255a which are in contact therewith. The insulating covering may be only partially applied, in other words, it is provided only in the contact regions between the housing portions and the other components.

The insulation effect may advantageously be achieved by phosphating individual components. Furthermore individual components such as for example the spring cups 259 and the peripheral abutments 255 and 255a may be produced from non-conducting material.

It is particularly advantageous for at least the sheet metal members and/or the flange to be phosphated for insulation purposes. The springs 245 may desirably be painted but they may also be phosphatecoated.

In order to insulate the housing portions 231 and 232 with respect to the components which are in contact therewith, it is also possible to use ceramic layers, plastics coatings or also coatings of grease. Such coatings may be applied in particular to the housing portions 231 and 232.

if the sheet metal portions 231 and 232 are completely covered in the insulation treatment, such as phosphating, it is desirable if, in the region of the weld zones and in the contact region for the suppiy of current, the insulating layer which has been previously applied in those regions is removed for example by a mechanical machining operation so as to ensure satisfactory electrical conductivity in those regions.

In regard to the choice of insulating means, care should always be taken to ensure that they are compatible with the viscous medium used in the passage-like receiving means 251.

The use of a phosphate coating as the insulating layer is particularly advantageous as it has a wear-reducing and self-lubricating action.

Furthermore, at the outside periphery the housing portion 231 has a seat 239 on which a toothed starter ring 240 is carried. As con sidered over its periphery, the starter ring 240 is connected at least at certain points to the housing portion 231 by a weld 240a. That is advantageous when the housing portion 231 is of a sheet metal construction as due to the limited wall thickness of the housing portion 231, the seat 239 does not extend over the full width of the toothed ring.

As can also be seen from Figure 5, the housing portion 231 on the engine side is made of material of greater thickness than the housing portion 232.

As can be seen from Figure 7, the periph eral abutments 255 and 255a shown in Figure 5 may be replaced by shaped portions such as pockets 255c and 255d which are im pressed into the sheet metal portions 231 and 232. The pockets 255c and 255d may advan tageously be used for positioning the two housing portions 231 and 232 in the welding operation relative to each other. For that pur pose, the welding apparatus has suitable projections which are matched to the pockets 255c and 255d. The projections on the weld ing apparatus may form the electrodes which feed the necessary welding current-into the housing portions 231 and 232. The projec tions may further apply to the housing por tions231 and 232 the axial pressure which is required for the welding operation.It is parti cularly advantageous in that respect for the projections to be so disposed in the welding apparatus that during the welding operation they are always at a predetermined spacing, whereby it is also possible to ensure that the two housing portions 231 and 232 are in a defined axial position relative to each other after the welding operation. That is important in regard to the springs 245 in the passage like receiving means 251 and in particular in regard to the defined spacing which is to be maintained between the two regions 260, 261 and the flange 241 therebetween and which influences the hydraulic or viscous damping action produced by the apparatus.

The detail of an apparatus 301, as shown in Figure 8, illustrates å flange 341 which has radial projections 344 formed on the outside periphery thereof. Force storage means in the form of coil springs'345 and 345a may be actuated by way of the projections 344, as was described with reference to the preceding Figures. The force storage means 345 and 345a are accommodated in a passage-like re ceiving means 351 formed by components of the flywheel element 303. The spring 345a is actuated directly by the radial projection 344 whereas a spring cup 359 is arranged between the spring 345 and the radial projection 344.

The projection 344 has shaped portions thereon, pointing in the peripheral direction, in the form of lugs or noses as indicated at 344a and 344b.

The spring cup 359 has a recess 359a into which the nose 344a engages. The nose 344a and the recess 359a are of such an arrangement and configuration that at least when the spring 344 is actuated, the cup 359 and by way thereof the end region of the compression spring 345 is held back or lifted off by the nose 344a, relative to the radially outward regions of the passage-like receiving means 351. For that purpose the radially inward region of the nose 344a forms an inclined run-on ramp 344c co-operating with a support region 359b of the spring cup 359.

The spring cup 359 is urged or drawn radially inwardly by the run-on ramp 344c on the nose 344a.

At a radially inward location the nose 344b has a bevel or inclined surface 344d which co-operates with the end turn of the spring 345a and urges or displaces it radially inwardly.

When using a spring cup 359, it is advantageous for at least the cross-section of the run-on ramp 344c to be adapted to the contour of the recess 359a so as to ensure that the spring cup 359 bears satisfactorily against the nose 344a or the projection 344, even when the spring cup 359 is turned.

Shaped portions or noses 344a or 344b may also be advantageously provided on the radial projections and/or the radial regions of the flanges as shown in Figures 1 to 7.

Such noses 344a and 344b have the advantage that, even at higher speeds of rotation, at least the end regions, that is to say some turns, of the coil springs are held at a radially outward location out of contact with other components or regions so that those spring turns can spring freely, that is to say, they do not produce a friction damping effect.

Furthermore it is possible to ensure by virtue of such noses 344a and 344b that even in ranges of speeds of rotation in which the friction which is normally present between the turns of the springs and radial support surfaces thereof is so high that the turns can no longer produce a spring effect, at least the end regions of the springs still have an elasticity or spring action. That is particularly advantageous for damping the high-frequency oscillations, of small angular amplitude, which occur in such speed ranges.

In the alternative embodiment of a unit 401, as shown in diagrammatic form in Figure 9, the flange 441 is sealingly riveted directly to the axial projection 443 on the flywheel element 404 in order to seal off the annular chamber 430 which is at least partially filled with a viscous medium, while furthermore a seal 474 is axially disposed between the flange 441 and the radial side wall 432 of the annular chamber 430, which is towards the flywheel element 404.

Disposed radially inwardly of the side wall 432 and axially between the flange 441 and a radial region 404a of the flywheel element 404, which is axially spaced from the flange 441, is a friction device 490 which is outside the annular chamber 430 which is at least partially filled with viscous medium. The dry friction device 490 has a friction disc 494 and friction rings 494a and 494b which are disposed on both sides thereof, the friction ring 494b being arranged axially between the friction disc 494 and the flange 441. Arranged on the side of the friction ring 494b which is remote from the friction disc 494 is a pressure disc 493 which is acted upon by a diaphragm spring 492 which is axially braced between the radial region 404a and the pressure disc 493.

At its outer periphery the friction disc 494a has radial profiling means 495 which are engaged with co-operating profiling means 495a formed oh the radial inward edge of the wall 432. Depending on the situation of use, the profiling means may be of a play-free configuration or they may permit a certain rotational play in the peripheral direction between the friction disc 494 and the wall 432 so that in that case the friction device- 490 can come into operation only after at least one of the springs of the damper 413 has become operative.

In the unit 501 which is diagrammatically shown in Figure 10, disposed radially inwardly of the damper 513 and adjoining the passagelike receiving means 551 on both sides of the flange 541 are respective seals 574 and 574a which sealingly co-operate with corresponding regions of the adjacent portions 532 and 531 which define the passage-like receiving means 551.

Radially inwardly of the seals 574 and 574a, the flange 541 is axially clamped between two discs 593 and 594, with the interposition of friction rings 594 a and 594b. The disc 594 is fixedly connected to the flywheel element 504 by way of spacer pins 567. The pressure disc 593 which is axially disposed between the flange 541 and the radial region 504a of the flywheel element 504 is acted upon by a diaphragm spring 592 which is axially engaged between the pressure disc 593 and the radial region 504a. Radially inwardly, the diaphragm spring 592 and the pressure disc 593 have cut-out portions or recesses which at least partially engage around the spacer pins 567 so that the diaphragm spring 592 and the pressure disc 593 are prevented from rotating with respect to the flywheel element 504.

The prestressing force of the diaphragm spring 592 determines the torque level at which the flange 541 can turn or slip relative to the flywheel element 504. Therefore, in conjunction with the radially inward regions of the flange 541, the components 592 to 594b form a force-locking clutch or slipping clutch 590.

In order to restrict the rotary movement between the flange 541 and the flywheel element 504, the flange may be provided at its inward region with projections which, as considered in the peripheral direction, engage radially between the spacer pins 567. The relative rotary movement can be limited by those radial projections on the flange 541 bearing against the spacer pins 567. However for many situations of use it may also be desirable not to have such means for limiting the relative rotary movement between the flange 541 and the flywheel element 504. In such cases the force-locking or slipping clutch 590 is so designed that the torque which can be transmitted thereby is greater than the nominal torque which is produced by the engine.

In accordance with a further development of the apparatus illustrated in Figure 10, in the event of limited relative rotary movement between the flange 541 and the flywheel element 504, additional force storage means in the form of coil springs may come into operation between the two discs 593, 594 and the flange 541. The springs may be accommodated in suitable recesses in the two discs 593, 594 and in the flange 541, while those recesses, as considered in the peripheral direction, may be disposed between the spacer pins 567. In such a design configuration of the apparatus it is advantageous for the springs disposed in the region of the forcelocking clutch or friction device 590 to have a substantially higher spring rate than the springs of the outer damper 513.

The friction damping action produced by the friction device 590 should also be substantially greater than the friction damping effect which is provided in the angular range of rotary movement of the damper 513 and which is produced inter alia by the seals 574 and 574a which bear against the flange 541.

With the described embodiments, it is also possible to produce a multi-stage spring characteristic between the corresponding flywheel elements by at least individual springs of a spring group or a damper being shorter than the angular spacing between the contact or actuation regions co-operating therewith. In addition, by using such springs which are shorter than the apertures or recesses or annular passage sectors which accommodate them, it is possible to provide an angular range of rotary movement which is free of return force, starting from a central or rest position, as between the two flywheel elements. That effect can be achieved for example in a construction as shown in Figures 5 and 6 by the springs 245 being of a smaller angular extent in the peripheral direction than the angle between the projections 244 and the abutments 255, 255a respectively.

The invention is not restricted to the em bodiments described and illustrated but also includes alternative forms which can be produced by combining individual elements or features which are described in connection with the various embodiments.

Claims

1. Apparatus for damping oscillations, in particular between an engine and a drive train, with a damping arrangement to be provided between two flywheel elements, wherein the input member is the one flywheel element which can be connected to the engine and the output member is the other flywheel element which can be connected to the drive train, for example by way of a clutch, characterised by at least three of the features set out below: a) the damping arrangement includes at least one annular passage (51; 141; 25; 551) of practically closed cross-section, which is formed by components (31, 32; 131, 132) of the one flywheel element (3) and which is at least partially filled with viscous medium such as a pasty agent and in which at least two force storage means (45; 145; 245) such as springs are contained and supported on the same diameter, b) the annular passage (51; 151; 251; 551) is, possibly except for a small gap (54; 254), closed by a flange body (41; 141; 241; 541) which is non-rotatably connected to the second flywheel element (4; 204; 504) and which projects radially into the annular passage (51; 151; 251; 551) and which forms the other support regions for the springs, c) the springs (45; 145; 245) between the flywheel elements (3, 4; 203, 204) permit at least a relative rotational movement of +25 degrees, starting from a centre position, d) with "n" springs (45; 145; 245) on the same diameter wherein 2 c n c 4, the individual springs (45; 145; 245) extend over 70 to 96% of an angular sector, wherein the angular sector is 360 degrees/n, e) the springs (45,; 145; 245) extend over 70 to 96% of the angular periphery of the apparatus (1; 101; 201; 501), and f) the springs (45; 145; 245) arranged in the passage-like receiving means (51; 151; 251; 551) are pre-curved at least approximately- to the radius on which they are arranged.

2. Apparatus according to claim 1 characterised in that the springs (45; 145 ; 245) can be supported on radial projections (44; 144; 244) which are formed by the flange body (41; 141; 241) and which open into the radial region of the annular passage (51; 151; 251).

3. Apparatus according to claim 1 characterised in that the springs (45; 145; -245) can be supported on radial projections (44; 144; 244) which are formed by the flange body (41; 141; 241) and which are contained in the radial region of the annular passage (51; 151; 251) and that said projections merge into a web portion which engages over the springs in the peripheral direction.

4. Apparatus according to claim 3 characterised in that the web portion is contained in a radial recess of the annular passage, which extends beyond the annular passage.

5. Apparatus according to one of claims 1 to 4 characterised in that the annular passage (51; 151; 251; 551) is formed from two shell-like bodies (31, 32; 131, 132; 231, 232; 531, 532).

6. Apparatus according to one of claims 1 to 5 characterised in that at least one of the shell-like bodies (231, 232; 432; 531, 532) is a shaped sheet metal member (231, 232; 432; 532).

7. Apparatus according to claim 6 characterised in that the annular passage (251) is formed by two half-shell-like shaped sheet metal members (231, 232).

8. Apparatus according to one of claims 1 to 7 characterised in that the support means for the springs (45; 145; 245) are formed by elements (56, 57; 155, 155a; 255, 255a) which are fitted into the annular passage (51; 151; 251) which is otherwise of a continuous configuration around the periphery of the arrangement.

9. Apparatus according to claim 8 characterised in that the support means are formed by shaped rivets (155, 155a; 255, 255a) which, in the neutral position of the damper, are disposed on both sides of the projections (144; 244).

10. Apparatus according to one of the preceding claims characterised in that the support means are provided by pocket-like shaped portions (255c, 255d) (Figure 7).

11. Apparatus according to one of claims 1 to 10 characterised in that at least one projection (144) on the flange body (141) is of smaller extent, as considered in the peripheral direction, than the support means (155, 155a) of the annular passage, which support means are provided on both sides of said projection.

12. Apparatus according to one of claims 1 to 10 characterised in that at least one projection (44) on the flange body (41) is of a greater extent, as considered in the peripheral direction, in comparison with the support means (55, 55a) in the annular passage (51), which support means are provided on both sides of the projection.

13. Apparatus in particular according to one of the preceding claims characterised in that intermediate layers (59; 159; 259; 359) are provided between at least individual ones of the projections (44; 144; 244; 344) and springs (45; 145; 245; 345), the cross-sectional areas of the intermediate layers which are towards the projections being matched to that of the annular passage (51; 151; 251) which accommodates the springs.

14. Apparatus according to claim 13 characterised in that the intermediate layers (59; 159; 259; 359) in the annular passage form displacement pistons for the viscous medium.

15. Apparatus according to claim 13 or claim 14 characterised in that the intermediate layers (59; 159; 259; 359) have an axial cutout portion or an axial recess.

16. Apparatus according to one of claims 1 to 15 characterised in that the annular passage (151) is not of a constant cross-section at least over portions of the longitudinal extent of at least some springs (145) (at 189).

17. Apparatus according to one of claims 1 to 16 characterised in that at least some of the regions of the annular passage (151) which are disposed in the end portions of the springs (145) when in the non-compressed condition are enlarged in cross-section (at 189) relative to the other regions of said passage (151).

18. Apparatus according to in particular one of the preceding claims characterised in that at least one further spring group (48; 148) of the damping arrangement is provided radially inwardly of the annular passage (51; 151).

19. Apparatus according to one of claims 1 to 13 characterised in that the flange body (41; 141) has radially outward openings (46; 146) which are separated from each other in the peripheral direction by radial projections (44; 144) and in which the -springs (45; 145) of the first spring group are accommodated, and radially further inwardly disposed apertures (47; 147) which are separated by radial web portions (50; 150) and in which the springs (48; 148) of the further spring group are disposed.

20. Apparatus according to claim 19 characterised in that intermediate layers are provided between at least individual ones of the radial web portions (50; 150) and springs (48; 148).

21. Apparatus according to claim 19 or claim 20 characterised in that the projections (44; 145; 244; 344) and/or the radial web portions (50; 150) of the flange body (41; 141; 241; 341) have noses (344a; 344b) which point in the peripheral direction and which engage into a recess (359a) in the intermediate layers (159; 259; 359) and/or into the spring ends.

22. Apparatus according to claim 21 characterised in that at least the end regions of the springs (45, 48145, 148; 245; 345, 345a) are fixed by the noses (344a, 344b) in such a way that they do not have any contact with the regions (49), which engage over them at a radially outward location, of the flange body (41) and/or the flywheel element (3; 203; 303) which accommodate them.

23. Apparatus according to one of claims 18 to 22 characterised in that the first spring group (45; 145) provided in the annular passage (51; 151) and the radially further inwardly disposed further spring group (48; 148) are arranged in parallel relationship between the flywheel elements (3, 4).

24. Apparatus according to one of claims 18 to 23 characterised in that the spring groups (45, 48; 145, 148) come into operation in a step-wise manner, that is to say in angularly displaced relationship.

25. Apparatus according to one of claims 18 to 24 characterised in that at least individual springs (148a, 148b) of at least one spring group (148) come into operation in a step-wise manner, that is to say in angularly displaced relationship.

26. Apparatus according to one of claims 18 to 22 or 24 and 25 characterised in that the first spring group in the annular passage and the radially further inwardly arranged further spring group are arranged between the flywheel elements in series relationship.

27. Apparatus according to one of claims 19 to 26 characterised in that a respective aperture (47; 147) is provided radially inwardly of each opening (46; 146), as considered in the peripheral direction.

28. Apparatus according to one of claims 19 to 27 characterised in that, as considered in the peripheral direction, the openings (46; 146) and the apertures (47; 147) are at least approximately equal in terms of angular extent.

29. Apparatus according to one of claims 19 to 28 characterised in that the first spring group (45; 145) and the further spring group (48; 148) each have a maximum of four force storage means.

30. Apparatus in particular according to one of claims 1 to 29 characterised in that radially inwardly of the annular passage (51; 151; 251) the housing halves or shell-like bodies (31, 32; 131, 132; 231, 232) have regions (60, 61; 160, 161; 260, 261) which face towards each other and which form a passage (62; 262) for the flange body (41; 141; 241) to pass therethrough.

31. Apparatus according to claim 30 characterised in that the mutually facing regions (60, 61; 160, 161; 260, 261) form circular ring-like surfaces which define a circular ringlike gap (62; 262) which opens into the annular passage (51; 151; 251).

32. Apparatus according to claim 31 char acterised -in that the gap width (62;262) at least approximately corresponds to the thickness of the flange body (41; 141; 241).

33. Apparatus according to claim 31 characterised in that the gap (62; 262) is 0.1 mm to 2 mm wider than the regions of the flange body (41; 141; 241) which are accommodated therein.

34. Apparatus in particular according to one of claims 18 to 33 characterised in that the housing halves or the shell-like bodies (31, 32; 131, 132) have axial recesses (63, 64) for accommodating the inner spring group (48; 148).

35. Apparatus accordimg to one of claims 18 to 34 characterised in that the axial re cesses (63, 64), the passage (62) for the flange body (41) and the annular passage (51) merge into each other.

36. Apparatus according to claim 34 or claim 35 characterised in that the recesses (63, 64) are matched at least in the radially outward region to the periphery of the cross section of the force storage means (48).

37. Apparatus according to one of claims 18 to 36 characterised in that the inner springs (48; 148) of the further spring group are pre-curved to at least approximately the diameter on which they are arranged.

38. Apparatus according to one of claims 1 to- 37 characterised in that the inner and/or outer springs (45, 48; 145, 148) are radially supported, at least under the effect of centri fugal force, against the web portions (49) of the flange body (41, 141), which engage over them in the peripheral direction.

39. Apparatus according to one of claims 18 to 37 characterised in that the inner springs (48; 148) are radially supported, at least under the influence of centrifugal force, against the surfaces which define the recesses (63, 64).

40. Apparatus according to one of claims 34 to 39 characterised in that the recesses (63, 64) are annular, that is to say they are continuous over the periphery of the appara -tus, and the support regions in the peripheral direction for the force storage means (48, 148) are formed by abutment elements (65, 66; 165, 166) which are mounted into the recesses.

41. Apparatus according to claim 40 char acterised in that the abutment elements are formed by shaped rivets (165, 166).

42. Apparatus according to claim 41 char acterised in that the engagement regions of the shaped rivets (165, 166) for the force storage means (148) are flat or flattened off.

43. Apparatus according to one of the pre ceding claims characterised in that the springs of the inner spring group are accommodated in apertures in two discs, which are rotation ally connected to the other flywheel element which can be connected to the drive train, and axially accommodate between themselves a flange body which couples the radially out ward and the radially inward spring groups in series.

44. Apparatus according to one of claims 1 to 43 characterised in that the one flywheel element (3; 203) has the one component (41; 141; 241) of an axial plug-in connection (42; 142, 242), said component having a profile means (72; 172; 272), and the other flywheel element (4; 204) has the co-operating profile means (73; 173; 273) of the connection (42; 142; 242) which non-rotatably couples the two flywheel elements (3; 4; 203, 204).

45. Apparatus according to claim 44 char acterised in that the spring groups (45, 48; 145, 148; 245) of the damping arrangement are accommodated in a chamber (30; 130; 230) which can be at least partially filled with a viscous or pasty medium and which is essentially formed by the components (31, 32; 131, 132; 231, 232) of the one flywheel element (3, 203) which can be connected to the engine, and the output member of the damping arrangement is formed by a flangelike component (41; 141; 241) which has profiling means (72; 172; 272) which can be brought into engagement with co-operating profiling means (73; 173; 273) provided on the other flywheel element (4; 204), and further one of the flywheel elements carries a sealing element (75; 175; 275) which, when the two flywheel elements (3, 4; 103, 104) are fitted together, comes to bear sealingly against a surface (77; 176b; 276b) of the other of the flywheel elements (4; 204).

46. Apparatus according to claim 44 or claim 45 characterised in that the flange-like output member (41; 141; 241) of the damping arrangement, like the flange body, has a non-rotatable coupling to the other flywheel element (4; 204) by way of the profiling means (72, 73; 172, 173; 272, 273) of the connection (42; 142; 242), but is not fixed axially.

47. Apparatus according to at least one of the preceding claims characterised in that the flange-like output member (41; 141; 241) of the damping arrangement, like the flange body, is mounted in an axially floating condition between the two housing halves or shelllike bodies (31, 32; 131, 132; 231, 232) of the flywheel element (3; 203) which can be connected to the engine.

48. Apparatus according to one of claims 44 to 47 characterised in that the co-operating profiling means (73; 173; 273) are provided at the outer periphery of a component (27; 172; 227) which is in the form of an annular disc and which is connected to the other flywheel element (4; 204).

49. Apparatus according to at least one of the preceding claims characterised in that the volume of the viscous medium accommodated in the chamber is such that the inner second spring group (48; 148) at least partially dips thereinto.

50. Apparatus according to one of the preceding claims characterised in that at least one friction means (75+77; 175+176b; 275+276b; 490; 574+574a+541; 590) is operative between the flywheel elements (3, 4; 203, 204;...).

51. Apparatus according to one of the preceding claims characterised in that at least one friction means (490) which has play in the peripheral direction is operative between the flywheel elements (Figure 9).

52. Apparatus according to claim 50 or claim 51 characterised in that the friction means is accommodated in the chamber for viscous medium, which is formed by the housing halves or shell-like bodies.

53. Apparatus in particular according to one of the preceding claims characterised in that additionally disposed outside the space or annular passage (451; 551) which is at least partially filled with viscous medium such as pasty agent is a dry friction damping means (490; 590) which is operative between the two flywheel elements (Figures 9 and 10).

54. Apparatus according to one of the preceding claims characterised in that disposed between the flywheel elements is at least one friction damping means (590) connected in series with the springs which are operative between the flywheel elements (Figure 10).

55. Apparatus in particular according to one of the preceding claims characterised in that the viscous damping and/or friction damping operative in parallel relationship with the inner spring group is substantially less than the friction damping and/or viscous damping in parallel relationship with the outer spring group.

56. Apparatus according to one of the preceding claims characterised in that at least individual ones of the springs are shorter than the arcuate portion between the abutments.