GB2321679A

GB2321679A - Hydrodynamic torque converter bridging clutch with valve opened in dependence on viscosity

Info

Publication number: GB2321679A
Application number: GB9808375A
Authority: GB
Inventors: Volker Middelmann; Marc Meisner; Juergen Freitag
Original assignee: LuK Getriebe Systeme GmbH
Current assignee: LuK Getriebe Systeme GmbH
Priority date: 1994-02-11
Filing date: 1995-02-07
Publication date: 1998-08-05
Anticipated expiration: 2015-02-07
Also published as: GB9808385D0; GB9808375D0; GB2321939A; GB2321939B; GB2321679B

Abstract

The bridging clutch which is mounted actively between an output member of the torque converter and the input member has an axially displaceable piston 136 which is provided on one side with an engagement chamber 124 for the bridging clutch and on the other side with a disengagement chamber 125. The bridging clutch has at least one valve 138 dependent on the viscosity of the fluid, and this valve influences the pressure difference existing between the two chambers and also the engagement force of the bridging clutch. The valve can additionally or alternatively control a fluid stream between the two chambers, and in this case the valve is opened in an upper viscosity range and is closed in a lower viscosity range.

Description

HYDRODYNAMIC TORQUE CONVERTER The invention relates to a hydrodynamic torque converter with a fluid-operated lock-up clutch, a pump wheel drivable by an input member and mounted with a turbine wheel and guide wheel in a work chamber, wherein the lock-up clutch which is mounted actively between an output member of the torque converter and the input member has an axially displaceable piston which is provided on one side with an engagement chamber for the lock-up clutch and on the other side with a digengagement chamber.

Torque converters of this kind are known for example from US-PS 4 640 395, US-PS 4 619 350 or US-PS 4 618 041.

With the known torque converters operating conditions can arise wherein although an opened lock-up clutch is desired or indeed necessary, this state of the lock-up clutch cannot be set at least for a short time. This may be the case for example in the event of low outside temperatures, namely because these can produce an increased viscosity in the oil and as a result the pump supplying the converter and gearbox cannot apply or maintain the desired volume flow or desired pressure to guarantee sufficient opening of the lock-up clutch by biasing the disengagement chamber. Such conditions can occur in particular when temperatures drop below 0 degrees Celsius. A further critical state can occur when engaging reverse gear because in most cases the modulation pressure, thus the pressure which is required to operate the gearbox clutches is increased, namely to the disadvantage of the converter system pressure. Under these operating conditions an undesired at least partial closing of the lock-up clutch takes place. The cause of this closing is a pressure force which is produced as an integral effect from the pressure paths on each side of the piston wherein the pressure paths are substantially determined by the kinematic or dynamic ratios of the fluid elements, that is substantially by their average circumferential speed and thus the speeds of the discs defining the chambers, and is thus dependent on the operating state, that is on the speed level of the pump and turbine or piston. Consideration of such pressure paths is provided in US PS 3 213 983.

The object of the present invention is to avoid the aforesaid disadvantages and to ensure a satisfactory functioning over the entire useful area of the torque converter. Fumthermore the torque converter as claimed in the invention should have a simple construction and allow cost-effective production.

According to the invention, there is provided a hydrodynamic torque converter with a fluid-operated lock-up clutch, a pump wheel drivable by an input member and mounted with a turbine wheel and guide wheel in a work chamber, wherein the lock-up clutch which is mounted for operation between an output member of the torque converter and the input member has an axially displaceable piston which is provided on one side with an engagement fluid chamber for the lock-up clutch and on the other side with a disengagement fluid chamber, wherein the lock-up clutch has at least one valve controlling communication between the chambers, the opening and closing of which is dependent on the viscosity of the fluid, wherein the valve influences the pressure difference existing between the two chambers and also the engagement force of the lock-up clutch and/or controls a fluid stream between the two chambers.

In alternative aspects of the invention, the opening and closing of the valve can be dependent on the rotational speed and the fluid temperature; on the rotational speed and the viscosity of the fluid; or on the rotational speed, the fluid temperature and the viscosity.

Since the oil supply in the disengagement chamber is very much dependent on the temperature or viscosity of the oil with known converter constructions at least at speeds near idling or below idling, thus at speeds below 700 - 100 rpm, as a result of the pressure difference existing between the pressures or pressure profiles arising either side of the converter piston it is possible for the lock-up clutch to occupy an at least partially engaged position so that undesired torque transfer takes place through--the lock-up clutch. This undesired engagement can occur particularly when engaging first gear or reverse gear. This is due to the fact that when engaging this type of gear when the vehicle is practically stationary the turbine and thus also the piston of the lock-up clutch is braked at least to a lower speed so that the dynamic forces acting on the oil contained in the ring chamber between the piston and turbine drop whereby in this ring chamber, viewed over the radial extension a greater pressure path is set. This is due to the fact that as a result of the drop in speed the dynamic forces or centrifugal forces on the oil decrease whereby the level of the pressure path increases radially inwards with decreasing speed. In extreme cases, that is when the turbine is stationary, roughly the same pressure can exist radially inwards in the ring chamber between the piston and turbine wheel as in the radially outer area of the converter housing. Thus an at least substantially uniform pressure level can be provided over the radial extension of the piston.

Through the invention it is ensured that in the aforesaid operating states in which an undesired closing of the lockup clutch is to be avoided a connection is provided between the two chambers so that a pressure compensation is guaranteed through an oil stream circulating between these two chambers whereby at least an inadmissibly high closing force is avoided. The connecting cross-sections between the two chambers are preferably dimensioned so that a friction engagement in the lock-up clutch is avoided. With the prior art this undesired engagement of the lock-up clutch is due to the fact that the "outer pressure difference", thus the pressure difference between the supply pressure applied by an oil pump for opening the lock-up clutch and the converter return pressure can be smaller than the mean pressure difference built up by the flow conditions either side of the piston.

As claimed in a preferred embodiment of the invention the valve is designed so that it opens in a lower speed and/or temperature area and is closed in a second higher speed and/or temperature area. Advantageously such a valve can have an element which is dependent on centrifugal force and through which the degree of opening or switching state of the valve is controlled. As claimed in an advantageous design of the invention the valve which is dependent on centrifugal force and/or temperature and/or viscosity is a slider valve and/or a rotary slider and/or a cock and/or a flap.

However it is also possible to use temperature-dependent valves, such as for example thermostatic valves, those based on the bimetal principle and those based on the memory principle. With valves having an element dependent on centrifugal force it is preferable if this element is biased in the opening direction of the valve by at. least a singlestage or multi-stage energy or force accumulator.

It can be particularly advantageous for the functioning of the invention if the valve is provided in the area of the inner edge section of the piston. It can thus modulate the pressure compensation taking place via the valve between the chambers either side of the piston in dependence on the radial arrangement of this valve or can be adapted to each individual case of use. However it is in most cases expedient if this valve is provided radially inside the mean diameter which is produced from the outer diameter and the inner diameter of the piston defining a central opening.

An advantageous design of the invention provides for a torque converter with lock-up clutch which---contains a torsion vibration damper and wherein the valve is mounted substantially radially inside the torsion vibration damper energy accumulator.

A further expedient design of the invention provides that the piston of the lock-up clutch has gearing in the radially inner area and the valve is mounted substantially radially in the area of the gearing of the piston or radially inside the gearing of the piston.

The valve as claimed in the invention can be designed so that it gradually closes over a certain speed range. In many cases however it can also be advantageous if the closing of the valve is carried out suddenly, thus abruptly.

Opening can be carried out in the same way wherein combinations of the two types of response can also be advantageous.

The torque converter as claimed in the invention can advantageously be used between an engine and a gearbox of a motor vehicle wherein the torque converter and the gearbox can be operated by a control or regulator system which is designed so that the clutch couplings of the gearbox and the converter lock-up clutch can be supplied with fluid by a common pump, wherein the control system furthermore has means which below a minimum operating temperature keep the converter lock-up clutch open and on exceeding this minimum temperature allow closing of the lock-up clutch wherein the valve connecting the engagement chamber and disengagement chamber together is designed so that below the minimum operating temperature this remains opened and on reaching the minimum operating temperature the valve is closed and/or is controlled dependent on temperature. This closing can take place gradually thus over a certain speed range or a certain temperature range. Closing of the valve-can also be brought about suddenly. The temperature-dependent valves can as already mentioned be constructed on the bimetal principle or memory effect. However it is also possible to use bi-stable spring elements dependent on temperature.

Such bi-stable elements occupy two different end positions in dependence on the temperature acting on same wherein these end positions can be occupied gradually in dependence on temperature or can be effected through a sudden snapping of the element.

An expedient embodiment of the invention can be designed where the valve is opened and/or closed deliberately stepwise or stepped. Furthermore with other embodiments it can be advantageous if the valve opens and/or closes deliberately gradually or suddenly.

The device as claimed in the invention with at least one valve which is preferably mounted radially inwards on the piston of the converter lock-up clutch is preferably designed so that operating the at least one valve is practically independent of the pressures prevailing in the chambers provided either side of the piston. These pressures should thus produce no forces in the closing or opening direction on the closing element of the piston. The valves should thus be independent of pressure. So-called slider valves can be used with particular advantage and these can be designed as longitudinal or rotary slider valves. These valves have the advantage over the so-called seat valves that their sealing or closing action is not dependent on the biasing of the sealing element by an energy accumulator or other surface force in the direction of a sealing seat. The valves can also be constructed as claimed in the throttle flap principle.

In one emboditment, slider valves are used which have a controllable valve passage or opening, the volume flow through which can be controlled or set or metered.

Several valves can advantageously be provided, preferably spread out evenly over the circumference. Combinations of different valves are also possible. Thus for example valves dependent on centrifugal force can be used in combination with temperature-dependent valves.

It is expedient if the valve is mounted inside the housing of the torque converter and/or the valve is connected to the piston of the converter lock-up clutch and/or is mounted on the piston of the converter lock-up clutch.

One advantage of the arrangement of the valve or valves in the converter housing and/or on the piston is a guarantee of the safety function since with a defective hydraulic system or in the absence of the hydraulic pressure supply the valve is mounted so that in this case a sudden or abrupt closing of the lock-up clutch is prevented. Thus for example when the vehicle is stationary and the converter lock-up clutch is open accidents as a result of a sudden closing of the lock-up clutch can be substantially avoided.

It can furthermore be expedient if the direction of the lift movement of the closure element of the valve at least at the beginning of the lift movement is at least substantially at right angles to the flow direction through the valve opening and/or valve.

Similarly it can be expedient if the lift movement of the closure element of the valve is not a purely translatory movement and the direction of the lift movement at least at the beginning of the lift movement is at least substantially at right angles to the flow direction through the valve opening and/or through the valve.

A further advantageous embodiment of the invention can be effected if the direction of the lift movement of the closure element is set and/or fixed at an angle greater than 00 to the flow direction, preferably between 300 and 90".

It can likewise be advantageous if with a valve with a direction of the lift movement which is substantially at right angles to the flow direction the function of the shutoff member is not or only slightly influenced by the internal converter pressure. It can be particularly advantageous if the valve is a slider valve.

In an advantageous design of the invention with a valve having a direction of the lift movement forming an angle substantially larger than 0 to the flow direction through the valve the function of the shut off member is not or only slightly affected by the internal converter pressure.

The invention will now be explained with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic illustration of a torque transfer system with a converter and a lock-up or lock up clutch as well as showing a diagram of the associated pressurised medium control; Figure 2 is a partial view in section of a hydrodynamic converter with lock-up clutch; Figure 2a is a view in the direction of arrow II of the valves as claimed in the invention in the opened state; Figure 2b* is the view as claimed in Figure 2a but wherein the valves are closed; Figure 3 is a partial view in section of another embodiment of a torque converter wherein the lock-up clutch has temperature-dependent valves; and Figure 3a is a view in the direction of arrow III of Figure 3 in which the valves are shown in their closed position.

The torque transfer system 10 shown in Figure 1 comprises a torque converter 11 and a lock-up clutch 12 which can be operated by a pressurised flow medium and which is connected in parallel with the torque converter. The torque transfer system is in active connection with the shaft 13 only indicated of an internal combustion engine (not shown) and is in driving connection on the output side through an output part 14 with an automatic gearbox connected into the output side of the output drive train and which is likewise not shown.

As shown in the diagrammatic semi-sectional view of the torque transfer system 10 in connection with the pressure control diagram the torque converter 11 is a conventional flow converter. This flow converter consists of a converter cover 16 connected as the input member to the output of an internal combustion engine, a pump wheel 17 forming together with the converter cover the converter housing, a turbine wheel 18 connected in turn by an output hub 14 as the output member to the automatic gearbox (not shown), as well as a guide wheel 19 mounted between the pump and turbine wheel.

The friction clutch 12 bridging the converter is mounted between the turbine wheel 18 and the converter cover 16 and has a clutch disc 20 connected in rotary connection with the output hub 14 of the converter. The friction face 21 of the clutch disc 20 interacts with a counter face 22 of the converter cover 16. The friction clutch furthermore has a rear chamber 24 facing the turbine wheel 18 and a front chamber 25 facing the radial wall of the converter cover 16.

The clutch disc 20 has a piston 20a which separates the two chambers 24,25 axially from each other and which is connected to the output hub 14 by a torsion damper 20b.

The converter 11 is supplied with pressurised flow means in known way from a source of pressurised medium such as an oil pump (not shown in further detail) through a pipe 30 opening on the pump wheel side into the converter housing wherein the pressure control is carried out through a control valve 31 which in turn is controlled by a control element 32.

This control element 32 can be formed by a proportional valve or a pulse-width-modulated valve which is set and operated by a computer unit or processor 32a, namely in dependence on the ensuing input values or parameters as well as the characteristic fields recorded in the processor. The pressurised flow medium is discharged through a pipe (not shown) to a cooler (33) only indicated. In addition to the biasing of the turbine wheel 18 the pressure of the flow medium also acts on the downstream side of the pump wheel 17 in the rear chamber 24 of the friction clutch 12. The pressurised medium biases the piston 20a and presses this against the counter face 22 of the converter cover 16.

Since as claimed in a preferred design variation of the invention the clutch is driven with slip at least in many operating areas the pressurised flow medium biasing of the chamber 25 on the front side is controllable by a valve 31 connected to this chamber through a pipe 34 so that an adjustable differential pressure acting between the rear 24 and front chamber 25 determines the torque which can be transferred by the friction clutch 12.

In view of the parallel arrangement of the converter 11 and the latter bridging friction clutch 12 the engine torque is equal to the sum of the torques which are transferred by the converter or pump wheel and by the clutch, thus MEngine = Clutch + MpUmp wheel The gearbox torque, if one disregards losses in the transmission system, equals the sum of the torques transferred by the converter or turbine wheel, thus MGearbox = MClutch + Turbine wheel or Mclutch + (Mpumpwheel x conversion).

With increasing slip the proportion of engine torque transferred by the converter increases and thus the torque transferred by the clutch decreases.

The control or regulation of the converter of the lock-up clutch can advantageously be carried out as described in German Patent Application P 43 22 974 or PCT Application 93/00765.

The torque transfer system 110 shown as an example in Figure 2 involves a hydrodynamic torque converter 111 with a lock up clutch 112 and a damper unit 135 acting between the clutch and the output 114.

The torque converter 111 comprises a pump wheel 117 in rotationally secured driving connection with an internal combustion engine (not shown), a turbine wheel 118 in active connection with a hub 114 on the output side, a guide wheel 119 mounted in the flow circuit between pump wheel and turbine wheel, and a converter cover or converter housing 116 connected rotationally secured to the pump wheel and enclosing the turbine wheel.

The converter cover 116 is connected rotationally secured with the pump wheel 117 and produces its driving connection with the internal combustion engine.

Between the turbine wheel 118 and the radial area of the converter cover 116 is a ring piston 136 which is central with the rotary axis of the converter. This ring piston 136 is set radially inwards on an output hub 114 connected rotationally fixed with the turbine wheel 118 and forms radially outwards a conical area which is fitted with a lining 121. The ring piston 136 interacts with a correspondingly conically designed counter friction face 122 of the converter cover 116.

The lock-up clutch 112 has a rear pressure chamber 124 between the ring piston 136 and the turbine wheel 118 and a front pressure chamber 125 between the ring piston 136 and the radial wall of the converter cover 116. The piston 136 is shifted from its coupling position where it interacts with the counter friction face 122 by biasing the front side pressure chamber 125 with flow medium. The size of the torque to be transferred by the friction clutch 112 is produced in dependence on the differential pressure set between the pressure chambers 124, 125 or the axial force produced on the piston 136 as a result of the said differential pressure.

On the radially inner areas 137 of the piston 136 are valves 138, namely two diametrically opposite valves are mounted as shown in Figures 2a and 2b. The valve 138 is shown closed in Figure 2.

The valves 138 are designed to be dependent on centrifugal force and are made as slider valves. A ring-139 fixed in the piston 136 has, as shown in Figures 2a and 2b, two circumferentially oblong slits 140 which, viewed axially, are aligned with correspondingly formed openings in the piston 136. Through the openings 140 it is possible to make a connection between the chambers 124,125 provided either side of the piston 136 whereby a pressure compensation can be carried out between these two chambers. Two segmentshaped closing elements 141 arranged mirror symmetrical diametrically opposite one another are guided on the ringlike component 139. The two closing elements 141 are displaceable in the radial direction, namely against the action of the springs 142 which bias these elements 141 radially inwards. The springs 142 are designed as tensile springs which are each connected with each of the closing or slider elements 141. Figure 2a shows the open position of the valves 138. This position is occupied by the valves 138 below a certain speed. This speed is determined by the mass of the slider elements 141, the spring rate of the springs 142 and their possible pretension. This open position as claimed in Figure 2a should be ensured below the idling speed of the internal combustion engine interacting with the torque converter 110. This speed can be in the order of for example between 700 and 1000 rpm. Depending on the type of use this speed can however also have smaller or larger values.

The radial guide of the slider elements 141 is produced through the side areas 143 of the radially outer projections 144 of the slider elements 141. These side areas 143 are guided by the side flanks 145 of the axial indentations 146 formed in the ring-like component 139. The edge areas 143 and the side flanks 145 are matched with each other accordingly. The radial projections 144 are thus taken up in the axial indentations 146 and are guided radially in these whereby a rotationally secured connection is guaranteed between the component parts 139 and 141.

On exceeding the aforesaid defined speed the slider elements 141 move radially outwards as a result of the centrifugal force acting on same whereby the slits 140 are closed. The closed position is shown in Figures 2b and Figure 2. In this position the arms 147 of the slider elements 141 provided laterally of the centre area 144 are supported on the inner sleeve face of the ring 139. The springs 142 are correspondingly tensioned through the radial displacement of the slider elements 141.

As can be seen from Figure 2a the cross-section of the openings 140 is comparatively large so that in the opened state closing of the lock-up clutch 112 and thus damaging torque transfer through the lock-up clutch is not possible.

The openings 140 are thus not intended to maintain any oil flow which may be necessary for cooling the friction faces of the lock-up clutch and also are provided to produce a defined soft engagement behaviour of the lock-up clutch.

These connecting openings 140 are mainly to ensure that in the states where the turbine wheel 118 and thus also the piston 136 are braked to a low speed the lock-up clutch 112 is at least substantially open. The latter is ensured in that with such states a pressure compensation between the two chambers 124,125 can be carried out through the bore 140 whereby, viewed radially, the pressure curves or pressure distributions either side of the piston 136 are compensated at least with regards to their tendency. The resulting force acting on the piston is thereby broken down at least in the engagement direction.

Advantageously the friction faces of the closed lock-up clutch 122 can be cooled by a cooling oil stream provided between the two chambers 124, 125. In this- connection reference is made to German Patent Applications P 43 22 974, P 43 25 605 and P 44 01 656.

With the embodiment as claimed in Figures 3 and 3a a ringlike component 239 is fixed on the inner areas of the ring piston 236 in order to form valves 238. In the ring like component 239 and in the piston 236 there are axially coinciding bores 240 which connect with the radial bores 240a which are open to the inner sleeve face of the component 239. As can be seen from Figure 3a tHere are four valves 238 evenly spread out over the circumference.

The closing element 241 of the valves 238 is formed by a temperature-dependent element which can be formed as a bimetal element or as a bi-stable spring element. In Figure 3 the open position of the valves 238 is shown fully extended and in Figure 3a the closed position.

The temperature-dependent closing elements 241 are preferably designed so that they keep the valves 238 open below a minimum operating temperature of the oil, for example 30"C and close the valves 238 when this temperature is exceeded.

Temperature-dependent valves of this kind can be used for example in a gearbox whose clutches are supplied from the same oil pump as the torque converter, with the gearbox and the torque converter being operable by a control or regulator system which is designed so that the shift couplings of the gearbox and the converter lock-up clutch can be supplied with fluid by a common pump. The control system can have means which keep the converter lock-up clutch open below a minimum operating temperature and allow the lock-up clutch to be closed when this temperature is exceeded.

The invention is not restricted to the embodiments described and illustrated but comprises in particular variations, within the scope of the claims, which can be formed by a combination of features and elements described in connection with the present invention. Furthermore individual features or functioning methods described in connection with the figures can be taken alone to represent an independent invention. The applicant reserves the right to claim as being essential to the invention further features which up until now have only been disclosed in the description, more particularly in connection with the figures.

The present application is divided out from earlier application 9502376.8 which describes and claims a hydrodynamic torque converter with a fluid-operated lock-up clutch, a pump wheel drivable by an input member and mounted with a turbine wheel and guide wheel in a work chamber, wherein the lock-up clutch which is mounted for operation between an output member of the torque converter and the input member has an axially displaceable piston which is provided on one side with an engagement fluid chamber for the lock-up clutch and on the other side with a disengagement fluid chamber, wherein the lock-up clutch has at least one valve controlling communication between the chambers, the opening and closing of which is dependent on the rotational speed of the clutch, wherein the valve influences the pressure difference existing between the two chambers and also the engagement force of the lock-up clutch and/or controls a fluid stream between the two chambers, wherein the valve is opened in a lower speed range and is closed in a second higher speed range.

Application 98 05 of C? (Agent's ref P1493.P3B) describes and claims a hydrodynamic torque converter with a fluidoperated lock-up clutch, a pump wheel drivable by an input member and mounted with a turbine wheel and guide wheel in a work chamber, wherein the lock-up clutch which is mounted for operation between an output member of the torque converter and the input member has an axially displaceable piston which is provided on one side with an engagement fluid chamber for the lock-up clutch and on the other side with a disengagement fluid chamber, wherein the lock-up clutch has at least one valve controlling communication between the chambers, the opening and closing of which is dependent on the temperature of the fluid, wherein the valve influences the pressure difference existing between the two chambers and also the engagement force of the lock-up clutch and/or controls a fluid stream between the two chambers, wherein the valve is opened in a temperature range and is closed in a second higher temperature range.

Claims

1. Hydrodynamic torque converter with a fluid-operated lock-up clutch, a pump wheel drivable by an input member and mounted with a turbine wheel and guide wheel in a work chamber, wherein the lock-up clutch which is mounted for operation between an output member of the torque converter and the input member has an axially displaceable piston which is provided on one side with an engagement fluid chamber for the lock-up clutch and on the other side with a disengagement fluid chamber, wherein the lock-up clutch has at least one valve controlling communication between the chambers, the opening and closing of which is dependent on the viscosity of the fluid, wherein the valve influences the pressure difference existing between the two chambers and also the engagement force of the lock-up clutch and/or controls a fluid stream between the two chambers.

2. Torque converter as claimed in Claim 1, wherein the valve which is dependent on viscosity is a slider valve and/or a rotary slider and/or a cock and/or a flap.

3. Torque converter as claimed in any preceding claim, wherein the valve has a viscosity-dependent element which controls the opening degree of the valve.

4. Torque converter as claimed in any preceding claim, wherein the valve has a component part designed according to the memory effect.

5. Torque converter as claimed in any one of Claims 1 to 4, wherein the activation of the valve is at least substantially independent of the pressures arising in the chambers.

6. Torque converter as claimed in any one of Claims 1 to 5, wherein the piston has a radially outer diameter and an inner diameter defined through a central opening and the valve is provided radially inside the mean diameter produced from the outer and inner diameters.

7. Torque converter as claimed in any preceding claim wherein the torque converter with lock-up clutch contains a torsion vibration damper and the valve is mounted substantially radially inside the torsion vibration damper energy accumulator.

8. Torque converter as claimed in any preceding claim, wherein the piston has gearing in the radially inner area and the valve is mounted substantially radially in the area of the gearing of the piston and/or radially inside the gearing of the piston.

9. Torque converter as claimed in any preceding claim, wherein the valve is provided on the radially inner areas of the piston.

10. Torque converter as claimed in Claim 1, wherein the valve is a slider valve.

11. Torque converter as claimed in any preceding claim, wherein the valve opens and/or closes in steps.

12. Torque converter as claimed in any one of Claims 1 to 11, wherein the opening and/or closing of the valve is carried out gradually.

13. Torque converter as claimed in any preceding claim, wherein the valve has an adjustable and/or controllable opening through which a volume flow is controlled or metered.

14. Torque converter as claimed in any preceding claim, wherein the valve is mounted inside the housing of the torque converter.

15. Torque converter as claimed in any preceding claim, wherein the valve is connected with the piston of the converter lock-up clutch and/or is mounted on the piston of the converter lock-up clutch.

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16. Torque converter as claimed in any preceding claim, wherein the direction of lift movement of a closure element of the valve at least at the beginning of the lift movement is at least substantially at right angles to the flow direction through the valve opening and/or through the valve.

17. Torque converter as claimed in any preceding claim, wherein the lift movement of the closure element of the valve is not a purely translatory movement and the direction of the lift movement at least at the beginning of this lift movement is at least substantially at right angles to the flow direction through the valve opening and/or through the valve.

18. Torque converter as claimed in any preceding claim, wherein the direction of the lift movement of the closure element is set and/or fixed at an angle greater than 0 to the flow direction, preferably however at 309 to 900.

19. Torque converter as claimed in any preceding claim, wherein with a valve with a direction of the lift movement substantially at right angles to the flow direction, the function of the shut-off member is not or only slightly affected by the inner converter pressure.

20. Torque converter as claimed in any preceding claim, wherein the valve is a slider valve.

21. Torque converter as claimed in any preceding claim, wherein with a valve with a direction of the lift movement which forms substantially an angle greater than 0 to the flow direction the function of the shut-off member is not or is only slightly affected by the inner converter pressure.

22. The apparatus of Claim 1, wherein said torque converter further comprises a stator disposed in said chamber between said pump and said turbine as seen in the direction of said axis.

23. The apparatus of Claim 1, wherein said at least one valve is a slide valve.

24. The apparatus of Claim 1, wherein said at least one valve is rotatable about said predetermined axle.

25. The apparatus of Claim 1, wherein said at least one valve is a cock.

26. The apparatus of Claim 1, wherein said at least one valve element is adjustable to establish at least one path for the flow of fluid between said compartments at a rate which varies as a function of the viscosity of the fluid in said chamber, said at least one valve being operative to permit the flow of fluid between said compartments in response to a rise of the viscosity of fluid above a preselected value and to at least reduce the rate of fluid flow between said compartments in response to a drop of the viscosity of fluid below said preselected value.

27. The apparatus of Claim 26, wherein said at least one valving element is movable in response to changes of the viscosity of fluid in said chamber to thereby vary the rate of fluid flow between said compartments.

28. The apparatus of Claim 27, wherein said at least one valving element is a bimetallic element.

29. The apparatus of Claim 27, wherein said at least one valve is a thesmostatic valve.

30. The apparatus of Claim 1, wherein said at least one valving element is arranged to vary the rate of fluid flow between said compartments in accordance with a memory effect.

31. The apparatus of Claim 1, wherein said piston includes a radially inner portion having a first diameter and surrounding a central opening of the piston and a radially outer portion having a second diameter larger than said first diameter, said at least one valve being nearer to said radially inner portion than to said radially outer portion.

32. The apparatus of Claim 1, wherein said lockup clutch further comprises a torsional vibration damper between said piston and said output member, said damper being disposed at a first radial distance and said at least one valve being disposed at a lesser second radial distance from said axis.

33. The apparatus of Claim 1, further comprising a torsional vibration damper installed between said output element and said output member, said damper having at least one energy storing element disposed at a first radial distance and said at least one valve being disposed at a lesser second radial distance from said axis.

34. The apparatus of Claim 1, wherein said piston has a toothed radially inner annular portion disposed at a first radial distance from said axis, said at least one valve being disposed at a second radial distance from said axis and said second distance at most matching said fist distance.

35. The apparatus of Claim 1, wherein said piston includes a radially inner portion which is spaced apart from said axis and said at least one valve is adjacent said radially inner portion.

36. The apparatus of Claim 1, wherein said at least one valving element is movable between open and closed positions to thereby respectively permit the fluid to flow between said compartments and to at least substantially prevent the fluid from flowing between said compartments, and means for moving said valving element at least from one of said positions to the other of said positions in stepwise fashion.

37. The apparatus of Claim 1, wherein said at least one valving element is movable between open and closed positions to thereby respectively permit the fluid to flow between said compartments and to at least substantially prevent the fluid from flowing between said compartments, and means for gradually moving said valving element, at least from one of said positions to the other of said positions.

38. The apparatus of Claim 1, wherein said lock-up clutch further comprises a torsional vibration damper between said piston and said output member, said damper being disposed at a first radial distance and said at least one valve being disposed at a lesser second radial distance from said axis, said at least one valving element being movable between open and closed positions and said at least one valve further comprising means for gradually moving said at least one valving element at least from one of said positions toward the other of said positions in accordance with a predetermined program.

39. The apparatus of Claim 1, wherein said lock-up clutch further comprises a torsional vibration damper between said piston and said output member, said damper being disposed at a first radial distance and said at least one valve being disposed at a lesser second radial distance from said axis, said at least one valving element being movable between open and closed positions and said at least one valve further comprising means for abruptly moving said at least one valving element to at least one of said positions.

40. The apparatus of Claim 1, wherein said piston has a toothed radially inner annular portion disposed at a first radial distance from said axis, said at least one valve being disposed at a second radial distance from said axis and said second radial distance at most matching said first distance, said at least one valving element being movable between open and closed positions and said at least one valve further comprising means for abruptly moving said at least one valving element to at least one of said positions.

41. The apparatus of Claim 1, wherein said at least one valve has at least one opening which establishes said at least one path for the flow of fluid between said compartments, and means for varying the rate of fluid flow through said at least one opening.

42. The apparatus of Claim 41, wherein said means for varying the rate of fluid flow includes means for regulating the rate of fluid flow through said at least one opening in accordance with a predetermined pattern.

43. The apparatus of Claim 1, wherein said torque converter further comprises a housing which defines said chamber, said at least one valve being disposed in said housing.

44. The apparatus of Claim 1, wherein said at least one valve is connoted with said piston.

45. The apparatus of Claim 1, wherein said at least one valve is mounted on said piston.

46. The apparatus of Claim 1, wherein said at least one valving element is movable between an open position to thus establish a flow of fluid between said compartments in a first direction and a second position in which said at least one valving element at least reduces the rate of fluid flow between said compartments, said at least one valve further comprising means for moving said at least one valving element from said second position in a second direction at least substantially at right angles to said first direction.

47. The apparatus of Claim 46, wherein said means for moving includes means for imparting to said at least one valving element a composite movement including a movement in said second direction at least during a first stage of movement from said second position and a movement in a third direction during a next-following stage of movement from said second position.

48. The apparatus of Claim 1, wherein said at least one valving element is movable between an open position to thus establish a flow of fluid between said compartments in a first direction and a second position in which said at least one valving element at least reduces the rate of fluid flow between said compartments, said at least one valve further comprising means for moving said at least one valving element at least from one of said positions to the other of said positions at an angle to said first direction.

49. The apparatus of Claim 48, wherein said angle is between about 300 and about 90".

50. The apparatus of Claim 1, wherein said at least one valving element is movable between open and closed positions to thereby influence the rate of fluid flow between said compartments in a first direction, said at least one valving element being movable from at least one of said positions toward the other of said positions in a second direction substantially at right angles to said first direction and at least substantially independently of fluid pressure in at least one of said compartments.

51. The apparatus of Claim 1, wherein said at least one valving element is movable between open and closed positions to thereby influence the rate of fluid flow between said compartments in a first direction, said at least one valving element being movable from at least one of said positions toward the other of said positions in a second direction at an angle greater than 0 to said first direction and at least substantially independently of fluid pressure in at least one of said compartments.

52. Apparatus for transmitting torque as claimed in any preceding claim between a rotary output element of an engine in a motor vehicle and a rotary input element of an adjustable transmission in the vehicle, comprising a hydrokinetic torque converter including a pump driven by said output element and a turbine driven by said pump and arranged to drive said input element; an engageable and disengageable lock-up clutch which is engageable to transmit torque from said output element to at least one of said turbine and said input element; a regulating unit arranged to operate said torque converter and to adjust said transmission; a pumping device controlled by said unit and arranged to supply a hydraulic fluid to said transmission and to said clutch, said unit including means for maintaining said clutch in the disengaged condition when the fluid temperature in a chamber of said torque converter is below a given value and for permitting engagement of the clutch when the temperature of fluid in said chamber rises above said given value; and at least one valve operative to establish and to at least substantially seal a path between a first compartment and a second compartment of said chamber at opposite sides of a mobile piston of said clutch, said at least one valve including at least one valving element arranged to establish said path for the flow of fluid between said compartments when the fluid temperature in said chamber is below said given value and to at least reduce the rate of fluid flow between said compartments when the temperature of fluid in said chamber rises above said given value.

53. The apparatus of Claim 52, wherein said piston has a radially inner portion and said at least one valve is adjacent said radially inner portion of said piston.

54. The apparatus of Claim 52, wherein said at least one valving element is movable in response to changes of the temperature of fluid in said chamber to thereby vary the rate of fluid flow between said compartments.

55. The apparatus of Claim 54, wherein said at least one valving element is a bimetallic element.

56. A torque transmitting apparatus as claimed in any preceding claim, comprising a hydrokinetic torque converter having a fluid-containing chamber and including a pump rotatable about a predetermined axis at a variable RPM by a rotary output element of a prime mover, and a turbine disposed in said chamber and including an output member rotatable about said axis; a lock-up clutch engageable to transmit torque of variable magnitude from said output element to said output member and disengageable to interrupt the transmission of torque from said output element to said output member, said clutch including a rotary piston moveable in the direction of said axis and dividing said chamber into first and second compartments respectively containing bodies of a fluid at first and second pressures, the differential between said pressures determining the magnitude of torque being transmitted by said clutch; and at least one valve which is adjustable to establish at least one path for the flow of fluid between said compartments at a rate which varies as a function of the temperature of the fluid in said chamber to thus influence the pressure differential and hence the magnitude of torque being transmitted by said clutch, said at least one valve being operative to permit the flow of fluid between said compartments in response to a drop of fluid temperature below a predetermined value and to at least reduce the rate of fluid flow between said compartments in response to a rise of fluid temperature above said predetermined value.

57. The apparatus of Claim 56, wherein said at least one valve is adjustable to establish at least one path for the flow of fluid between said compartments at a rate which varies as a function of the viscosity of fluid in said chamber, said at least one valve being operative to permit the flow of fluid between said compartments in response to a rise of the viscosity of fluid above a preselected value and to at least reduce the rate of fluid flow between said compartments in response to a drop of the viscosity of fluid below said preselected value.

58. The apparatus of Claim 56, wherein said piston is rotatable at a plurality of speeds and said at least one valve is adjustable to establish at least one path for the flow of fluid-between said compartments at a rate which varies as a function of the RPM of said piston, said at least one valve being operative to permit the flow of fluid between said compartments in response to a reduction of the RPM of said piston below a predetermined RPM and to at least reduce the rate of fluid flow between said compartments in response to a rise of the RPM of said piston above said predetermined RPM.

59. A torque transmitting apparatus comprising a hydrokinetic torque converter having a fluid-containing chamber and including a pump rotatable about a predetermined axis at a variable RPM by a rotary output element of a prime mover, and a turbine disposed in said chamber and including an output member rotatable about said axis; a lock-up clutch engageable to transmit torque of variable magnitude from said output element to said output member and disengageable to interrupt the transmission of torque from said output element to said output member, said clutch including a rotary piston movable in the direction of said axis and dividing said chamber into first and second compartments respectively containing bodies of fluid at first and second pressures, the differential between said pressures determining the magnitude of torque being transmitted by said clutch; and at least one valve which is adjustable to establish at least one path for the flow of fluid between said compartments at a rate which varies as a function of the viscosity of fluid in said chamber to thus influence the pressure differential and hence the magnitude of torque being transmitted by said clutch, said at least one valve being operative to permit the flow of fluid between said compartments in response to a rise of the viscosity of fluid above a preselected value, and to at least reduce the rate of fluid flow between said compartments in response to a drop of the viscosity of fluid below said preselected value.

60. The apparatus of Claim 59, wherein said piston is rotatable at a plurality of speeds and said at least one valve is adjustable to establish at least one path for the flow of fluid between said compartments at a rate which varies as a function of the RPM of said piston, said at least one valve being operative to permit the flow of fluid between said compartments in response to a reduction of the RPM of said piston below a predetermined RPM and to at least reduce the rate of fluid flow between said compartments in response to a rise of the RPM of said piston above said predetermined RPM.

61. The apparatus of Claim 59, wherein said at least one valve is adjustable to establish at least one path for the flow of fluid between said compartments at a rate which varies as a function of the temperature of fluid in said chamber, said at least one valve being operative to permit the flow of fluid between said compartments in response to a drop of fluid temperature below a predetermined value and to at least reduce the rate of fluid flow between said compartments in response to a rise of fluid temperature above said predetermined value.