EP1617047B1 - Connecting element for fixation of a lever type cam follower - Google Patents

Description

Field of the invention

The invention relates to a connecting element for the captive mounting of a lever-like cam follower, which serves to actuate a gas exchange valve of an internal combustion engine, on a support element with a spherical end on which the cam follower is pivotally mounted by means of a dome-shaped indentation, wherein the connecting element in an annular groove below the Spherical end engages.

Background of the invention

Such fasteners are known to allow the generation of a unit that includes, for example, a cam follower as a cam follower and a support element. With such a unit, the risk of potential incorrect assembly at the customer is minimized. This could include, among other things, that the drag lever is rotated by 180 ° in the valve train is mounted. In this case the contact partners would be ball head of the Supporting element and dome of the finger lever and valve stem end and corresponding mating surface swapped on the rocker arm. Such incorrect assembly would lead to at least a valve train malfunction and in the worst case even to a serious engine failure. Other requirements of this connecting element are that on the one hand separation of rocker arm and support element is reliably excluded by transport influences and on the other hand, the connecting element makes no detrimental contribution to Ventiltriebsreibung during the pivoting movement of the rocker arm on the support element.

In the DE 102 49 560 A1 is a connecting element which satisfies the aforementioned requirements advantageous proposed. In this connecting element made of flat material, the spherical end of the support element is clipped behind an oval recess of the connecting element, which is located below the dome-shaped indentation of the finger lever. Although this engages the connecting element in the annular groove below the spherical end, but still allows a minimum friction pivotal movement in the direction of actuation of the gas exchange valve. However, a prerequisite for a perfect clipping of the support element behind the connecting element is its elastic deformation in the region of the recess. The required elasticity can be easily achieved by suitable geometry of the recess and suitable properties and strength of the connecting element material, yet a mounting gap remains transverse to the direction of actuation of the finger lever between the connecting element and annular groove in the support element. Consequently, the drag lever is not completely hindered by the connecting element in a pivoting movement transversely to its actuating direction, said pivoting movement can then be up to 15 °. Such a tilting of the finger lever about its longitudinal axis can also occur in the assembled internal combustion engine, namely contact loss between rocker arm and the actuating cam. Causes of such a loss of contact can be an undesirable sinking of the most commonly used support elements with hydraulic lash adjuster or a removal of the finger lever from the actuating Cams may be due to an overspeed of the internal combustion engine.

In this regard, especially cam followers with a very narrow cam contact surface are to be observed. These are used in space-constrained multi-valve engines or in variable valve controls, in which a cam of different cams different cam existing cam is mounted axially displaceable on its camshaft and of which a to the operating state of the engine matching cam is brought into engagement with the cam follower. The drag lever is then particularly at risk of further or complete tipping off the support element, since it is unable to align sufficiently with the cam on renewed contact with its cam due to the narrow cam contact surface.

Object of the invention

The object of the invention is therefore to provide a connecting element of the aforementioned type, wherein the cited disadvantages are eliminated, so that in particular cam followers with a narrow cam contact surface stable alignment can be ensured on the actuating cam in all operating states of the internal combustion engine.

Summary of the invention

The solution to this problem arises from the features of claim 1, while advantageous developments and refinements the dependent claims are removed.

Accordingly, the object is achieved in that a central portion of the connecting element rests against a supporting element facing the underside of the cam follower and with two legs and a web connecting them in the longitudinal direction of the cam follower U-shaped recess which forms the groove like a fork and orthogonal to the pivoting the cam follower essentially encompasses clearance, wherein angled from the legs Holding claws extend in the transverse direction of the cam follower, which engage over the side walls like a pliers, that is clamped by clamping the retaining claws by means directed on inner sides of the associated side walls, the U-shaped recess with respect to their position in the transverse direction to the cam follower and its shape is substantially fixed ,

As a result, the disadvantages mentioned are eliminated by simple means. The design of the connecting element ensures that the cam follower is connected captively to the support element and at the same time minimizes its possibility of tilting about its longitudinal direction. The latter is achieved mainly in that the connecting element engages around the annular groove in a U-shaped manner so that it can be pulled onto the cam follower in a shoe-like manner, while the spherical end of the supporting element is already in the dome-shaped recess. Thus, an elastic deformation of the connecting element, as occurs in a clipping of the support element, and the associated mounting gap between the connecting element and annular groove no longer required. The low elasticity requirement also allows the use of a connecting element of high material thickness, which effectively hampers tilting of the cam follower in addition to the freedom from play to the annular groove and high component stiffness.

The thickness of the legs can still be so limited that it is less than the axial width of the groove, so that the connecting element is geometrically free to move in the direction of actuation of the gas exchange valve in the groove during pivotal movements of the cam follower. In this respect, the connecting element takes part deformation-free in the pivoting movement of the cam follower and also generates no additional friction during operation of the gas exchange valve.

The connecting element is intended to be mounted on the cam follower preferably made of a resilient material, such as spring-hard steel. Alternatively, light metal or plastic, reinforced with fibers or particles is to be used. Particularly preferred is the use of a flat material.

The lever-like cam follower is expediently a drag lever. This drag lever may have a sliding surface or, more preferably, a rotatably mounted roller as a cam contact surface. Finally, the drag lever should have a generally U-shaped cross-section. Instead of the U-shaped cross section may also be provided only a U-like cross-section or an H-section or the like. In combination, it is stated that the drag lever is made of sheet metal material. Of course, at this point, other materials suitable for the function are also conceivable, including plastics or forming levers, wherein the protective region of this invention also includes the U-shape without combination with the sheet metal material.

Short description of the drawing

Figur 1

eine Seitenansicht auf das erfindungsgemäße Verbindungselement bei betriebsbereit montiertem Zustand des Ventiltriebs,

Figur 2

eine Rückansicht des Ventiltriebs im Teilschnitt

Figur 3

eine perspektivische Darstellung des erfindungsgemäßen Verbindungselementes.

The invention is explained in more detail with reference to the accompanying drawings, in which an embodiment is shown. Show it:

FIG. 1

a side view of the connecting element according to the invention when the valve drive is ready mounted state,

FIG. 2

a rear view of the valve gear in partial section

FIG. 3

a perspective view of the connecting element according to the invention.

Detailed description of the drawing

FIGS. 1 to 3 show a cam follower 1 and a support element 2 which supports it in a pivotable manner and which here is provided with a hydraulic not-shown Valve clearance compensation is executed. The cam follower 1 is driven in a conventional manner via a cam 3 by means of a connected to the cam follower 1 and rotatably mounted roller 4 in the direction of actuation of a gas exchange valve 5. Of course, instead of the roller 4 and a rigidly connected to the cam follower 1 sliding surface can be provided as a cam contact. The cam follower 1 is a drag lever in the embodiments shown, which has a U-shaped cross-section and is preferably made of sheet material in a forming process.

The cam follower 1 has a dome-shaped indentation 6, by means of which it is mounted on a spherical end 7 of the support element 2. As can be seen in particular from FIG. 2, below the spherical end 7 there is an annular groove 8 into which a connecting element 9 consisting of flat material engages. The connecting element 9 rests with a central portion 10 on an underside 11 of the cam follower 1 facing the support element 2. The central portion 10 has two legs 12, 13, which are interconnected by a web 14 and form a U-shaped recess 15 in the longitudinal direction of the cam follower. From Figure 2 it can be seen that while the legs 12, 13 engage around the groove 8 perpendicular to the operating direction of the cam follower 1 without play.

Of the legs 12, 13 go in an oblique direction of the cam follower 1 angled retaining claws 16, 17, the side walls 18, 19 of the cam follower 1 engage over like tongs. In this case, end portions 20, 21 of the retaining claws 16, 17 on formations 22, 23, which are directed to inner sides 24, 25 of the side walls 18, 19. The thus formed retaining claws 16, 17 generate a clamping of the connecting element 9 on the side walls 18, 19 of the cam follower 1. This clamping generates on the one hand acting in the longitudinal direction of the cam follower 1 frictional engagement with the connecting element 9, so that even in the operating state of the internal combustion engine slipping on the cam follower 1 is effectively prevented. On the other hand, the position of the U-shaped recess 15 is fixed relative to the dome-shaped indentation 6 by the clamping.

It is also readily apparent that for the assembly process, the connecting element 9 is easily pushed onto the cam follower 1, while the spherical end 7 of the support element 2 is already in the dome-shaped indentation 6. Thus, the connecting element 9 can be made with high material thickness and low elasticity, to hinder tilting of the cam follower 1 in addition to the freedom from play to the annular groove effectively by high component stiffness.

The legs 12,13 still have a material thickness which is less than the axial width of the groove 8. Thus, the connecting element 9 is freely movable during pivoting movements of the cam follower 1 in the direction of actuation of the gas exchange valve 5 in the groove 8, so that it is in operation Internal combustion engine neither deformed nor contributing to their friction contributed.

As materials for the connecting element 9 of the invention, of course, any materials come into question, as long as they meet the technical and financial requirements. So, of course, in addition to resilient steel and light metal materials and plastics, which may have a particle or fiber reinforcement, possible. These have a negligible proportion of the moving masses of the valve train due to their low density.

reference numeral

1

cam follower

2

supporting

3

cam

4

role

5

Gas exchange valve

6

dome-shaped indentation

7

spherical end

8th

groove

9

connecting element

10

central section

11

bottom

12

leg

13

leg

14

web

15

U-shaped recess

16

Retaining claw

17

Retaining claw

18

Side wall

19

Side wall

20

end

21

end

22

formation

23

formation

24

inside

25

inside

Claims (7)

1. Connecting element (9) for captively retaining a lever-like cam follower (1), which serves to actuate a gas exchange valve (5) of an internal combustion engine, on a support element (2) which has a spherical end (7) on which the cam follower (1) is pivotably mounted by means of a spherical-cap-shaped formed depression (6), with the connecting element (9) engaging into an annular groove (8) below the spherical end (7), characterized in that a central section (10) of the connecting element (9) bears against an underside (11), which faces towards the support element (2), of the cam follower (1), and forms, together with two limbs (12, 13) which are spaced apart from one another and a web (14) which connects said limbs, a recess (15) which is U-shaped in the longitudinal direction of the cam follower (1) and engages substantially without play around the groove (8) in the manner of a fork, orthogonally with respect to the pivoting direction of the cam follower (1), with retaining claws (16, 17) which are angled away from the limbs (12, 13) running in the transverse direction of the cam follower (1), which retaining claws (16, 17) engage in the manner of tongs over the side walls (18, 19) of said cam follower (1) in such a way that, as a result of clamping of the retaining claws (16, 17) by means of formations (22, 23) which are aligned on inner sides (24, 25) of the associated side walls (18, 19), the U-shaped recess (15) is substantially fixed in terms of its shape and in terms of its position in the transverse direction with respect to the cam follower (1).
2. Connecting element according to Claim 1, characterized in that the connecting element (9) can be pushed onto the cam follower (1) parallel to the longitudinal direction of the latter, with the spherical end (7) of the support element (2) already being situated in the spherical-cap-shaped formed depression (6) as the connecting element (9) is pushed on.
3. Connecting element according to Claim 1, characterized in that the limbs (12, 13) have a material thickness which is smaller than the axial width of the groove (8), so that during pivoting movements of the cam follower (1), the connecting element (9) is geometrically freely moveable in the groove (8) in the actuating direction of the gas exchange valve (5).
4. Connecting element according to Claim 1, characterized in that the connecting element (9) is composed of a resilient material such as cold-hammered steel or light metal or of a plastic, optionally with fibre- or particle reinforcement.
5. Connecting element according to Claim 1, characterized in that the connecting element (9) is composed of flat material.
6. Connecting element according to Claim 1, characterized in that the cam follower (1) is a rocker arm.
7. Connecting element according to Claim 6, characterized in that the rocker arm has a generally U-shaped cross section and is produced in a non-cutting process from sheet metal material.

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