EP1659268A1 - Cup-shaped tappet for an internal combustion engine - Google Patents

Abstract

The tappet has an anti-twist protection unit (6) inserted in a radial recess of a shell and stepping forward in a radial direction from the shell. The unit has an outer contour in a longitudinal section, where the contour has a head (20) and a shaft (21), which has dimension that is reduced opposite to the head. The shaft has a bulge (32) and is clamped into the recess under elastic deformation of the bulge.

Description

Field of the invention

The invention relates to a tappet for an internal combustion engine according to the preamble of claim 1.

Background of the invention

From DE 196 00 852 A1 a bucket tappets for an internal combustion engine is known, which is interposed between a control cam and a valve. The tappet has a shirt, which is approximately hollow cylindrical and is guided in a bore of the cylinder head. The shirt has a radial recess into which an anti-rotation element is inserted, which avoids a rotation of the bucket tappet about the lifting axis relative to the cylinder head in that the anti-rotation element engages in the circumferential direction both positively in the tappet and in a suitable groove of the cylinder head. For this purpose, the anti-rotation element protrudes radially out of the shirt. According to a first embodiment, the anti-rotation element is designed as a cylinder body whose longitudinal axis is oriented in the stroke direction and the end faces radially have from the outside opening grooves, in which engages a projection of the shirt. The outside of the shirt lying lateral surface of the anti-rotation element engages in the groove of the cylinder head, while the inner circumferential surface rests against an inner body of the bucket tappet. According to a second embodiment, the anti-rotation element is designed as an elastic spring element in the form of a U-shaped clasp with two legs and a back. The clip is inserted with its legs radially inwardly into the recess of the tappet under elastic deformation until indentations of the legs engage in the boundaries of the recess of the shirt in the circumferential direction. According to a third embodiment, the anti-rotation element is designed as a hollow cylindrical, slotted sleeve whose longitudinal axis is oriented in the stroke direction. The sleeve has opposite impressions, in which engage under elastic deformation of the sleeve, the boundaries of the recess of the shirt in the circumferential direction.

From DE 28 29 423 C2 an anti-rotation is known, which does not serve to prevent rotation between the bucket tappet and the cylinder head, but rather between individual components of the bucket tappet. The special feature of the anti-rotation device known from this publication is that this serves in addition to the function of a rotation by a central Ölzuführbohrung an oil supply.

From DE 41 15 670 A1 a trained as a fitting anti-rotation is known, which is designed as a thin-walled sheet - or plastic part. The fitting is supported centrally on a web of the cylinder head and is located off of this web of two bucket tappets to prevent rotation of the same. A final fixation of the shaped piece takes place here by an assembly of the camshaft or a clamping of the shaped piece between a guide housing and the cylinder head.

DE 43 24 756 C2 discloses a bucket tappet, which has an outer cup with an inner tappet, with a hydraulic compensating element slidably guided in the outer cup. An anti-rotation engages thrust movable in a guide groove on the receiving bore in the cylinder head and in an opening of the outer cup. The anti-rotation element additionally engages in a guide groove of the inner plunger with a relatively large inner guide length or contact surface. This enlarged inner guide length serves for a secure guidance between the inner tappet and the cup and prevents tilting of the outer guide length in the guide groove of the cylinder head. As a result, the occurrence of chatter marks is avoided in the guide, which can lead to jamming.

From DE 195 01 061 A1 a bucket tappet is known in which a shirt abuts an inner part. In this case, the anti-rotation element does not protrude beyond the inner jacket of the shirt. The inner end face of the anti-rotation element is formed corresponding to a sub-segment of a lateral surface of a cylinder, so that the inner part over a large area on the aforementioned end face and an inner circumferential surface of the shirt can rest.

For example, from DE 199 57 772 A1 an anti-rotation element is known, which is cylindrical with a longitudinal axis in the direction of the stroke direction. The outside of the cup tappet arranged lateral surface is guided in a guide groove with a circular segment-shaped contour corresponding to the outer contour of the cylinder.

Further anti-rotation elements are known for example from DE 101 23 966 A1 and DE 43 37 330 A1.

Object of the invention

The invention has for its object to provide a non-rotating cup tappet, the simple production possibility of the cup, in particular the recess of the shirt, and / or the anti-rotation element ensures easy installation and a good function and reliability.

Summary of the invention

According to the invention the object is solved by the features of independent claim 1.

Accordingly, the anti-rotation element has a special outer contour such that it has a head and a shank in the longitudinal section of the anti-rotation element. This outer contour may have the anti-rotation element, for example in the installed state in a section through the longitudinal axis of the anti-rotation element and the axis of the stroke direction and / or by the longitudinal axis and an oriented in the circumferential direction of the tappet axis. With the head and the shaft in particular a mushroom-shaped outer contour is given.

According to the invention, the anti-rotation element further has a thickening in the region of the shaft. The anti-rotation element can be clipped into the recess of the shirt with elastic deformation of the thickening. It is clear that also corresponding longitudinal sides of the recess experience an elastic deformation.

• deren Gestaltung und Außenkontur,
• die Materialwahl und -paarung für Verdickung, Schaft und die Begrenzung der Ausnehmung,
• die Höhe der Verdickung,
• etwaige Einführschrägen der Verdickung,

die für eine Montage erforderliche Kraft vorgegeben werden, die für ein Einklipsen notwendig ist. Andererseits kann über die vorgenannten Parameter vorgegeben werden, wie gut die Sicherung des Verdrehsicherungselements in der Ausnehmung des Hemdes ist, da für ein Herausfallen des Verdrehsicherungselements oder ein Verkanten oder eine Veränderung der Lage eine erneute Aufbringung der elastischen Verformung erforderlich ist. Hierbei ist es durchaus möglich, dass die notwendigen Kräfte einerseits für ein Einklipsen und andererseits für ein Entfernen des Verdrehsicherungselements unterschiedlich sind, beispielsweise über eine Gestaltung der Kontur oder der Materialpaarung der Verdickung und insbesondere über etwaige Einführ- und Ausführschrägen in den Randbereichen der Verdickung.By prescribing the thickening can over

• their design and outer contour,
• the material selection and pairing for thickening, shaft and the boundary of the recess,
• the height of the thickening,
• any chamfers of thickening,

given the force required for a mounting, which is necessary for a clipping. On the other hand, can be specified via the aforementioned parameters How good is the securing of the anti-rotation element in the recess of the shirt, since a re-application of the elastic deformation is required for falling out of the anti-rotation element or tilting or changing the position. In this case, it is entirely possible that the necessary forces are different on the one hand for clipping and on the other hand for removing the anti-rotation element, for example via a design of the contour or the material pairing of the thickening and in particular over any insertion and extension bevels in the edge regions of the thickening.

According to the invention, the dimension transverse to the longitudinal axis in said section of the head is greater than the at least one partial region of the shaft. This ensures that the head is supported with a relatively large distance from the longitudinal axis relative to the outer surface of the shirt. As a result, on the one hand, the lever arm of the support can be increased. On the other hand, the length of a support line or the size of a support surface is increased according to the invention. As a result, there is an improved securing of the anti-rotation element with respect to a tilting relative to the shirt, whereby an improved positional assurance takes place. In addition to an thereby brought about improved protection against accidental falling out of the anti-rotation element this also has advantages in terms of the leadership of the anti-rotation element in the guide, since u. U. also a slight tilting is at least reduced, whereby an increased guiding accuracy can be brought about. These advantages can not be met in particular with a clip according to the second embodiment according to DE 196 00 852 A1.

Another advantage of the design according to the invention is that the tolerances due to the elastic deformation of the anti-rotation element both for anti-rotation and for the wall thickness of the tappet and the contour of the recess can be made larger, as tolerated any deviations from an ideal by an elastic deformation can be. For an oblique education at least an abutment surface, there is an even further improvement in the tolerance of such deviations, since not an exact position is given on the slopes, but a slight displacement of a contact surface (at the expense of a modified press-in force) is possible. This can u. U. unnecessary a grouping of cup and anti-rotation element.

According to a development of the bucket tappet according to the invention, the shank has two partial regions, namely a first partial region which forms the thickening, and a second partial region, which is arranged between the first partial region and the head. The outer dimension of the second portion is smaller than that of the thickening. The anti-rotation element is clipped in the radial direction with sense of direction into the interior of the bucket tappet in the recess, in which case the outer dimension of the first portion, ie the thickening, is elastically reduced. This elastic reduction is oriented in particular in the circumferential direction. In the installed state, the anti-rotation element opposite the shirt is secured radially inwardly with a bearing surface formed by the head, with which the head rests against the outer surface of the shirt. In addition, a contact surface is provided which secures the anti-rotation element radially outward. This contact surface is formed by the transition region from the first partial region to the second partial region.

According to a first embodiment, this transition region can be formed as a jump, so that a contact surface formed transversely to the longitudinal axis of the anti-rotation element is formed. In this way, a particularly good assurance of the axial position of the anti-rotation element can be brought about in the recess, since with a loading of the anti-rotation element in the radial direction, a positive securing takes place via the two contact surfaces.

According to a second embodiment, the transition region is formed as a slope. This has the consequence that upon application of the anti-rotation element radially outward, the force is divided into a force oriented in the longitudinal direction of the anti-rotation element and a transverse force oriented transversely to the longitudinal axis of the anti-rotation element. This transverse force acts on an elastic reduction of the outer dimension of the first portion or the thickening, so that under certain circumstances for disassembly with sufficient application of a force radially outward the clipped connection can be solved again and the tappet can be removed from the recess. By a suitable design of the slope or a corresponding curved course, the force required for disassembly force can be dimensioned so that there is an optimum for reliability and allow disassembly.

Preferably, the tappet according to the invention is equipped with an anti-rotation element, which is made of a solid material. For such a solid material there are particularly good possibilities for a production, which can be made less expensive under certain circumstances. It is also possible that for a solid material particularly defined stiffness properties, in particular in the region of thickening, result and / or results in a particularly good fatigue strength of the anti-rotation element.

According to a development of the bucket tappet according to the invention the anti-rotation element is made of plastic, for example of a thermoplastic or a thermoset, or any metal having the desired mechanical properties. The abovementioned materials can be used, for example, via casting, forming, injection molding or machining. For example, a forming production from a metal sheet is possible.

According to a particular embodiment, the anti-rotation element is made of a continuous casting profile. In this case, it is conceivable that the contour according to the invention in the aforementioned longitudinal section corresponds to the outer contour of the continuous casting profile, from which then the individual anti-rotation elements be separated or punched out. The material used is, for example, a metal 100 CR 6.

In the case of the cup tappet according to the invention, the distance of the abovementioned contact surfaces preferably correlates with the wall thickness of the shirt in the region of the recess. Here, the wall thickness and the distance of the contact surfaces form a transition fit, a press fit or a clearance.

For a particular embodiment of the tappet, the anti-rotation element is designed to be multifunctional. In such a multifunctional design, the anti-rotation element can serve in addition to the rotation of an oil supply from the outside into the interior of the tappet. Alternatively or additionally, it is possible for an end region remote from the head of the anti-rotation element, for example with an end face or a side face, to serve a (twisting) securing for an inner body of the tappet.

According to a particular embodiment of the invention, the recess of the shirt is approximately rectangular in cross-section and has longitudinal and transverse sides, which are connected to each other via rounded corner regions. The longitudinal and transverse sides each have, for example, approximately centrally, projections. In the region of the transverse sides, the projections form contact areas which receive the anti-rotation element in the stroke direction with a transition fit. Projections in the region of the longitudinal sides form contact areas, which come into operative connection with the thickening of the anti-rotation element and between which in the mounted position, the second portion is added. A production of such a recess with a sufficient manufacturing accuracy is particularly well possible, since for the remote areas of the projections of the recess (rounded corner areas) a relatively large tolerance can be selected, since they do not come into functional operative connection with the anti-rotation element. For the longitudinal sides and transverse sides associated projections same or different manufacturing accuracies are selected according to the requirements mentioned. In this case, it is possible, for example, for the protrusions to be initially produced with a certain degree of oversize and to be brought to a desired level in a subsequent operation.

In the event that the anti-rotation element has an insertion phase, this can be particularly easily introduced radially inwardly into the recess during assembly, wherein the insertion form guide surfaces in an inaccurate insertion.

A further improved contact surface between the anti-rotation element and the shirt of the bucket tappet results when the head associated with the bearing surface is curved according to the lateral surface of the shirt. In this way, punctiform or linear contact areas can be avoided, since the head rests on a large area on the lateral surface of the shirt. This results in improved support conditions.

Brief description of the drawings

Figur 1

einen Tassenstößel bei Schnitt in Richtung der Hubachse H-H;

Figur 2

eine Kontur einer radialen Ausnehmung eines Hemdes eines Tassenstößels bei Blickrichtung radial zur Hubachse H-H;

Figur 3

ein Verdrehsicherungselement im Längsschnitt und

Figur 4

ein vergrößertes Detail einer Außenkontur des Verdrehsicherungselements gemäß Figur 3.

Further features of the invention will become apparent from the following description and the accompanying drawings, in which an embodiment of a tappet according to the invention is shown schematically. Show it:

FIG. 1

a bucket tappet when cut in the direction of the lifting axis HH;

FIG. 2

a contour of a radial recess of a shirt of a cup tappet when viewed radially to the lifting axis HH;

FIG. 3

an anti-rotation element in longitudinal section and

FIG. 4

an enlarged detail of an outer contour of the anti-rotation element according to FIG. 3

Detailed description of the invention

• Figure 1 shows a tappet 1 with a cup 2, which has a bottom 3, which cooperates with a control cam, and a shirt 4. The shirt 4 is approximately hollow cylindrical in shape and in a suitable bore of the internal combustion engine, in particular the cylinder head, in the direction of Hub axis HH displaceably guided, wherein the lateral surface of the shirt 4 serves as a guide surface. The shirt 4 has a radial recess 5, wherein in the present application is referred to radially a direction transverse to the lifting axis H-H. In the recess 5, an anti-rotation element 6 is inserted in the radial direction, which is supported in the circumferential direction about the lifting axis H-H and in the stroke direction H-H relative to the boundary of the recess 5. According to FIG. 1, the radially inner part of the anti-twist element 6 arranged by the shirt 4 engages positively in an inner body 7 of the bucket tappet 1, whereby it is fixed in the direction of the lifting axis H-H as well as in the circumferential direction or limited in its displacement. Radially outboard the anti-rotation element 6 is positively received in the circumferential direction about the lifting axis HH in a guide groove of the bore for the tappet 1, which extends in the direction of the lifting axis HH, so that via the anti-rotation element 6 a displacement of the tappet 1 in the direction of the lifting axis HH not is hindered, while a rotation of the bucket tappet 1 is excluded or limited to the lifting axis HH. The anti-rotation element 6 is shown in Figure 1 only schematically and shown for the present invention in detail different from Figure 1.
• Figure 2 shows a contour of the boundary of the recess 5. Accordingly, the recess has longitudinal sides 8, 9 and transverse sides 10, 11, which form approximately a rectangle. The recess 5 has rounded corner portions 12, 13, 14, 15 and approximately central projections 16, 17, 18, 19 which are parallel to opposite projections 16-19 and at right angles to adjacent Projections 16-19 are oriented and extend approximately over half the length of the longitudinal and transverse sides 8-11.
• FIG. 3 shows an anti-rotation element 6 according to the invention. Anti-rotation element 6 has a head 20 and a shaft 21, which are connected to one another via an undercut 22, in particular with a constant radius. The anti-rotation element 6 is formed in the longitudinal section shown in Figure 3 symmetrical to the longitudinal axis L-L. The head 20 has a contour that is curved, in particular partially or semicircular, and in particular has a surface which corresponds to a partial section of a lateral surface of a cylinder.

The contour of the anti-rotation element 6 can be seen in an enlarged partial longitudinal section according to FIG. The head forms with an end face a contact surface 23, whose inclination corresponds approximately to the inclination of the associated region of the lateral surface of the shirt 4. Preferably, the contact surface 23 in the longitudinal section shown in Figure 4 is circular-segment-shaped, wherein the radius of the contact surface 23 corresponds to the distance of the lateral surface of the shirt 4 and the head 20 in the installed state of the lifting axis HH and the center of the circular segment-shaped contour of the contact surface 23rd is in the installed state on the lifting axis HH.

The shaft 21 has a portion 24, which is assigned to the head 20 remote from the end face 25 of the shaft 21. The portion 24 has a chamfer 26, which serves to simplify the insertion of the anti-rotation element 6 in the recess 5. At the portion 24 includes in the direction of the head, a transition region 27. In the transition region 27, the distance of the contour shown from the longitudinal axis LL is continuously increased, for example, with an oblique or curved course. The transition region 27 is adjoined by a first partial region 28 with a straight outer contour at a constant distance from the longitudinal axis LL. To the first portion 28 includes a transition region 29, in which the distance from the longitudinal axis LL rectilinear or curved decreases up to a second portion 30 with a straight contour and a constant distance from the axis LL. The second portion 30 has the undercut 22 in the end region for the transition to the head 20.

4, the anti-rotation element 6 has approximately a constant contour at a substantially constant distance from the longitudinal axis L-L. Perpendicular to the plane of the drawing, the extension is such that the anti-rotation element 6 is received with suitable end faces with a clearance fit, transition fit or an interference fit between the abutment surfaces of the shirt 4 formed by the projections 16, 18.

With insertion of the anti-rotation element 6 into the recess 5, the partial region 24 with the chamfer 26 initially comes into operative connection with the projections 17, 19, whereby a centering effect is achieved and a further insertion of the partial region 24 in the radial direction inward is made possible. Upon further radial insertion of the anti-rotation element 6, the contact force between the boundary of the recess 5 and the transition region 27 is increased according to the distance of the contact area of the longitudinal axis LL in the region of the transition region 26, which with an elastic deformation of the shirt 4 or the anti-rotation element 6 radially goes along inside. In the first portion 28, the anti-rotation element 6 can be moved radially inwards, overcoming the frictional force between the first portion 28 and the boundary of the recess 5. In the transition region 29, the contact pressure between the anti-rotation element 26 and the boundary of the recess 5 is reduced, as a result of the bevel under certain circumstances, the transition region 29 supports the movement radially inwardly. A movement takes place until the head 20 comes with the contact surface 23 for engagement with the outer surface of the shirt 4.

In the mounted position so that the shirt 4 between the contact surface 23 and a system formed in the transition region 29 investment line or surface 31 is free of play or added to form a game or under bias. The spacing of the abutment surfaces 23, 31 corresponds to the wall thickness of the shirt 4. The subregion 24, transition region 27 and first subregion 28 can fulfill further functions in the assembled state.

In the operating state results due to the positive engagement of the invention between the two contact surfaces 23, 31 no significant change in position of the anti-rotation element 6 relative to the cup 2. The anti-rotation element 6 and the recess 5 are inexpensive to produce. This results in at least a reduced scrap and a reduction of any necessary rework as a result of tensions caused by interference fits. Furthermore, the manufacturing tolerances for the recess 5 and the anti-rotation element 6 can be made larger, whereby the manufacturing cost can also be reduced. A grouping of the anti-rotation element 6 and the associated cup 2 is possible according to the invention, but may no longer be necessary.

For a particular embodiment, the distance of the projections 17, 19 in the circumferential direction is 3.07 mm, while the portion 24 in the circumferential direction has an extension of 3 mm, the first portion 28 has an extension of 3.17 mm and the second portion 30 an extension of 3.07 mm. The material used is in particular a continuous casting profile in which the longitudinal surfaces form the contour according to FIG. 4 and which is separated into individual pieces in the direction of the lifting axis HH. The material is, in particular, 100 CR 6. A thickening 32 is formed in the region of the first subregion 28.

LIST OF REFERENCE NUMBERS

1

tappets

2

Cup

3

ground

4

shirt

5

recess

6

anti-rotation

7

inner body

8th

long side

9

long side

10

transverse side

11

transverse side

12

rounded corner area

13

rounded corner area

14

rounded corner area

15

rounded corner area

16

head Start

17

head Start

18

head Start

19

head Start

20

head

21

shaft

22

Clear cut

23

contact surface

24

subregion

25

front

26

chamfer

27

Transition area

28

first subarea

29

Transition area

30

second subarea

31

contact surface

32

thickening

Claims (10)

Cup tappet for an internal combustion engine with a shirt (4), which has a radial recess (5) into which an anti-rotation element (6) is inserted, which emerges from the shirt (4) in the radial direction, characterized in that the anti-rotation element (6 ) a) has an outer contour in longitudinal section with a head (20) and a shank (21) which has at least in the longitudinal section a relation to the head (20) reduced dimension and a thickening (32), and b) with elastic deformation of the thickening (32) in the recess (5) can be clipped. Cup tappet according to claim 1, characterized in that a) the shaft (21) has a thickening (32) forming the first portion (28) and between the first portion (28) and head (20) arranged second portion (30) whose outer dimension is smaller than that of the thickening (32 ) b) the anti-rotation element (6) with elastic reduction of the outer dimension of the first portion (28) in the recess (5) can be clipped in the radial direction and c) in the installed state, the anti-rotation element (6) relative to the shirt (4) is secured radially inwardly with a bearing surface (23) formed by the head (20) and radially outward of one in the transition region (29) of the first portion ( 28) to the second portion (30) formed contact surface (31) is secured. Cup tappet according to claim 1 or 2, characterized in that the anti-rotation element (6) is made of a solid material. Cup tappet according to one of the preceding claims, characterized in that the anti-rotation element (6) is made of plastic or a metal. Cup tappet according to one of the preceding claims, characterized in that the anti-rotation element (6) is made of a continuous casting profile. Cup tappet according to one of claims 2 to 5, characterized in that the distance of the contact surfaces (23, 31) with the wall thickness of the shirt (4) correlated. Cup tappet according to one of the preceding claims, characterized in that the anti-rotation element (6) is designed to be multifunctional. Cup tappet according to one of the preceding claims, characterized in that the recess (5) is approximately rectangular in cross-section with longitudinal sides (8, 9), transverse sides (10, 11) and rounded corner regions (12, 13, 14, 15) and projections (16, 18) for forming abutment areas in the region of the transverse sides (10, 11), which receive the anti-rotation element (6) in the stroke direction (HH) with a transition fit, and projections (17, 19) for forming abutment areas in the region of the longitudinal sides (8, 9), which with the Thickening (32) of the anti-rotation element (6) come into operative connection and between which in the mounted position of the second portion (30) is added. Cup tappet according to one of the preceding claims, characterized in that the anti-rotation element (6) has a chamfer (26). Cup tappet according to one of the preceding claims, characterized in that the head (20) associated with abutment surface (23) corresponding to the lateral surface of the shirt (4) is curved.

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