WO2007082623A1

WO2007082623A1 - Lever-type cam follower

Info

Publication number: WO2007082623A1
Application number: PCT/EP2006/070094
Authority: WO
Inventors: Van Hau Nguyen
Original assignee: Schaeffler Kg
Priority date: 2006-01-21
Filing date: 2006-12-21
Publication date: 2007-07-26
Also published as: DE102006002994A1

Abstract

The invention relates to a lever-type cam follower (1) for a valve train in an internal combustion engine. Said follower consists of sheet metal and has two lateral walls (2), which, together with a transverse section (3) that links the walls, form an inverted U-shaped profile in cross-section. The underside (4) of a transverse section (3) is equipped at one end (5) with a structure (6) for a gas exchange valve, said structure having lateral guide sections (7) on the inner faces (8) of the lateral walls (2). According to the invention, the upper face (9) of the transverse section (3) is pushed downwards towards the valve in the vicinity of the structure (6) in a stamping and extrusion method, in such a way that in said region the cam follower (1) has an approximately M-shaped cross-section. A cam follower (1) of this type has excellent rigidity. The height of the guide sections (7) can be adjusted relatively easily. In addition, there is no need for separate lugs to guide the valve shaft.

Description

Name of the invention

Lever-like cam follower

description

Field of the invention

The invention relates to a lever-type cam follower made of sheet steel, which is provided for a valve train of an internal combustion engine, with two side walls which form a reverse U-like profile together with a cross bar connecting them, wherein at one end of the crossbar at one end a plant is provided for a gas exchange valve.

Background of the invention

The next-genre document is DE 195 43 657 A1 (see FIGS. 4a, 10-13). From one end face of the disclosed therein cam follower two spaced guide tabs, which are bent to an underside of the crossbar. Between these guide tabs one end of a valve stem is feasible. At the end, the guide plates can be welded to the crossbeam (see DE '657, section 2, section 3).

It is disadvantageous in the aforementioned embodiment that the strip-like design of the guide tabs is relatively expensive to produce. Due to their welding, there is an undesirable heat input into the material. Optionally, weld beads or the like. Functional surfaces such as the system adversely affect. It also states that the Guide plates unnecessarily increase the length of the respective sheet metal blank (before the forming process).

Object of the invention

The object of the invention is therefore to provide a cam follower of the aforementioned type, in which the indicated disadvantages are eliminated.

Solution of the task

According to the invention this object is achieved by the novel features of claim 1. It is apparent that an upper side of the crossbeam in the area of the installation is passed through in the valve direction by an embossing extrusion process in such a way that the cross-sectionally inverted U-shaped cam follower in this section has an M-like geometry.

Thus, the aforementioned disadvantages are eliminated by simple means. The cam follower is especially stiff in the area of its installation at one end. In addition, its manufacturing costs are reduced compared to the aforementioned cam follower. A depth of "push through" makes it easy to set a height of the guide sections on the side walls, avoiding contact with an underlying valve spring retainer, and requiring only a relatively short section of blank plate per cam follower.

Towing, swing or rocker arms are particularly suitable as cam followers. If appropriate, the geometry of the system generated according to the invention can also be present in a casting follower or a generally differently produced cam follower. The system can be put through by such an amount in the valve direction that its thickness corresponds to the thickness of the respective side wall, is larger or smaller. The thickness of the system achieved after passing through / shifting can correspond to the original thickness of the board, but can also be larger or smaller. The aforementioned forming process can be carried out cold or hot.

Because according to an expedient development of the invention, the cam follower may consist of at least three sections of different widths, wherein the section of least width may be in the region of one end, the cam follower (drag lever) has only a small moment of inertia about its pivot point.

The recess in the cam follower according to another subclaim on the one hand reduces its mass. On the other hand, it allows an engagement of a roller as a cam counterface. This roller can run on a roller bearing on a bolt which is arranged in the end holes in the side walls in the region of the recess.

The bulged in accordance with a further development of the invention proposed course in the middle section optionally increases the rigidity of the cam follower.

Short description of the drawing

The invention is suitably explained in more detail with reference to the drawing. Show it:

Figure 1 is a perspective view of the cam follower;

Figure 2 shows a cross section through the cam follower in the region of

Plant and the FIG. 3 shows a plan view of the cam follower according to FIG. 1.

Detailed description of the drawing

Shown is a lever-like cam follower 1, which is designed here as a drag lever. The cam follower 1 consists of thin-walled sheet steel and can be generated in a stamping and bending process, for example, from sheet-metal strip.

The cam follower 1 has two substantially upright side walls 2, which are connected by a transverse bar 3. Due to the overhead connection of the crossbar 3, the cam follower 1 in cross section has an inverted U-like profile. On a bottom 4 of the crossbar 3, a flat system 6 is arranged for a gas exchange valve at one end. For lateral guidance of this gas exchange valve are used on inner sides 8 of the side walls 2 formed guide sections. 7

Behind the thus present first section 17 of the cam follower 1 with the system 6, there follows a second, middle section 18 (see also FIG. 3). The crossbar 3 has in this central region a recess 22. The side walls 2 here have two opposing holes 23. In these an axis with a role as a cam contact surface can be arranged or arranged. This roller can optionally run on the axis via a needle bearing or the like. However, it is also conceivable a slide bearing.

As Figure 1 is also removed, the side walls 2 are bulged in the central portion 18 in the direction away from the valve.

At the middle portion 18, a rear portion 19 connects. The transverse bar 3 has in this area a dome-shaped indentation 25 (see FIGS. 1, 3), via which it pivots on one end of a supporting element. is movably storable. Transition regions 20, 21 between the sections 17, 18, 19 are continuously rising, so that "rugged" transitions are not required here, so that the cam follower 1 is significantly narrower at one end 5 than at its other end 24 am Section 19.

As also shown in Figures 1, 2, an upper side 9 of the crossbar 3 in the area of the system 6 in the valve direction is put through. This can be achieved for example by a stamping extrusion process. Thus, the system 6 in the region of one end 5 in cross section has an M-like geometry. By means of an embossing stamp, a longitudinal channel 10 can be generated on the upper side 9 of the transverse bar 3, which, for example, does not extend into a region of the recess 22 on the middle section 18. However, an embodiment in which the longitudinal channel 10 intersects the recess 22 is also conceivable.

It can also be seen (see FIG. 2) that a distance from side surfaces 1 1 of the longitudinal channel 10 is smaller than a distance between the underlying guide sections 7 on inner sides 8 of the side walls 2.

Due to the insertion process, two channels 14 are achieved on the underside 4, which extend in the edge region 13 of the respective guide section 7 to the system 6. An outer wall 15 of the respective channel 14 can be seen as a smooth extension of the guide section 7. An inner wall 16, on the other hand, has an arcuate course in the direction of the installation 6.

As is also disclosed in the drawing, the crossbar 3 falls on its upper side 9 in the direction of the side walls 2 arcuate from, even in the region of the longitudinal channel 10th List of reference numbers

1) cam follower

2) side wall

3) Crossbeams

4) bottom

5) one end

6) attachment

7) guide section

8) inside

9) top

10) longitudinal channel

1 1) side surface

12) footprint

13) edge area

14) channel

15) outer wall

16) inner wall

17) section

18) section

19) section

20) Transition area

21) Transition area

22) recess

23) bore

24) other end

25) indentation

Claims

claims

1. lever-like cam follower (1), consisting of sheet steel and provided for a valve gear of an internal combustion engine, with two side walls (2), which together with a connecting them crossbar (3) in cross-section form an inverted U-like profile, wherein on a bottom (4) of the crossbar (3) at one end (5) a flat system (6) for a gas exchange valve with lateral guide sections (7) on inner sides (8) of the side walls (2) is provided and a top (9) of the crossbar ( 3) in the region of the system (6) is passed through such a stamping extrusion process in the valve direction, that the cam follower (1) in this section has an M-like geometry, on which upper side (9) thus formed longitudinal channel (10) in substantially upright side surfaces (1 1) and a flat base surface (12) is present, which side surfaces (1 1) less than the guide portions (7) of the side walls (2) in the same area apart lie.

2. cam follower according to claim 1, wherein in the edge region (13), between the respective guide portion (7) of the side wall (2) and the system (6), a channel (14) is formed, the outer wall (15) by a in substantially upright portion of the guide portion (7) and the inner wall (16) is formed by an arcuate portion of the system (6).

3. cam follower according to claim 1, wherein the cam follower (1) from at least three different width sections (17, 18, 19) is shown, wherein the portion (17) of smallest width in the region of one end (5) and transition regions (20 , 21) of the side walls (2) between the sections (17, 18, 19) are designed to widen as funnel-like.

4. cam follower according to claim 1, wherein the transverse bar (3) in a central portion (18) with a recess (22) is provided, in which the longitudinal channel (10) does not protrude.

5. cam follower according to claim 1 or 4, wherein the central portion (18) of the side walls (2) has a bulging away from the top (9) course.

6. cam follower according to one of claims 1, 4 or 5, wherein the side walls (2) in the central portion (18) with two bores (23) are provided, in which an axle with bearing thereon roll can be arranged or arranged as a cam counter surface.

7. cam follower according to one of the preceding claims, wherein the cam follower (1) is designed as a drag lever, wherein in a bottom (4) of the crossbar (3), at the other end (24), a dome-shaped indentation (25) Storage is applied to a head of a support element.