EP1357257B1 - Rocker arm made of sheet metal - Google Patents

Description

Field of the invention

The invention relates to a lever-like cam follower made of sheet metal, in particular for a valve train of an internal combustion engine, with two parallel, connected by a crossbar side walls, wherein a bottom of the crossbar at one end has a facility for at least one gas exchange valve, which system by running parallel to the side walls Guide cheeks is limited.

Background of the invention

Such a cam follower is considered from the considered generic DE 100 30 341 A1 out. This is also made of sheet metal and is optimized in the region of the valve stem support in terms of its width and weight. When installing such a cam follower in the internal combustion engine, it can still, despite all measures proposed there Space problems come. Furthermore, it should be noted that its mass moment of inertia is too high due to a still too large, undesirable mass accumulated away from the pivot point.

Especially in the case of four-valve or five-valve technology alone or in conjunction with very small cylinder clearances, it is clear to the engine construction expert that further optimization of the cam follower is necessary, at least in the region of the valve stem support, in order to solve the existing installation space problems.

Object of the invention

The object of the invention is therefore to provide a cam follower of the type described, in which the cited disadvantages are eliminated by simple means.

Summary of the invention

According to the invention this object is achieved in that the cam follower is narrower at one end than over its remaining extent, at least in this section the side walls a smaller average wall thickness than immanent over its further length, which wall thickness at least in this area of end faces the side walls continuously increases in the direction of the crossbar. In this case, a thickness of the guide cheeks may be smaller than the average wall thickness in the region of the narrow one end or substantially correspond.

As a result, there is a cam follower, which is further optimized in terms of its space. Its minimum width in the region of the valve stem support is ultimately determined by the thickness of the valve stem and the thickness of the mutually adjacent guide cheeks of the cam follower or by the distance of the outer surfaces of the side walls in this area.

Due to the narrow design of the cam follower at one end in conjunction with the - simply said - thinner than the side walls formed guide cheeks before a cam follower whose mass moment of inertia is further reduced and which requires at least in the valve stem support significantly less space than previously executed cam follower. At the same time it is particularly stiff and has, if it is made in the region of the valve stem support, for example, by a stamping extrusion, excellent strength in this area. Due to the continuously increasing thickness of the side walls at least at one end also squish wrinkles are effectively avoided in the transition region to the crossbar.

It is clear that the person skilled in the application varies from application to application height of the guide cheeks, which should prevent slippage of the cam follower during its assembly and during firing of the internal combustion engine.

The valve stem support is conveniently prepared in the abovementioned embossing extrusion or by cold forging, as or similar to that described in the introduction DE 100 30 341 A1 listed. For the "thinning" of the guide cheeks, material from their outsides is additionally used; This is done after bending the side walls and optionally using a partially thickened board. The Blechnockenfolger as such may be made of tape or solid material. Thought here is first and foremost on sheet steel, but it is also conceivable training from other familiar to the expert sheet types.

According to a further development of the invention, it is provided to form the narrow one end of the cam follower from a gradually tapering section. This embodiment is easy to implement in terms of manufacturing technology and prevents cracking in the transition region. It is also conceivable, however, to make the narrow one end as a stepped heel.

Characterized in that expires according to an expedient concretization of the invention, the narrow one end in a longitudinal section of equal width, the guide cheeks extend parallel to outer surfaces of the side walls. This has manufacturing advantages. It is also conceivable, however, to form the narrow one end as a whole tapering to a point. The length of the narrow-held portion of the cam follower and the narrowest possible guide cheeks and side walls in the guide cheek section optimizes the skilled artisan by appropriate calculation methods until, with sufficient rigidity, etc. Optimum lightweight construction is given in this area.

A particularly important feature of the invention is that the guide cheeks are integrally connected to and extend away from the underside of the crossbeam, their outsides being clearly engaged against outer surfaces of the sidewalls in the region of the one end. Thus, it is clear that the guide cheeks are formed from the material of the soil and are clearly not seen as an extension of the side walls. This has, as already described in the introduction, production and installation space technical advantages.

It is also conceivable, however, a solution in which the guide cheeks are formed as separate components that do not originate at least from the bottom of the crossbar at least. In the case of a design of the guide cheeks as separate elements they can be attached by suitable fastening methods such as welding, gluing or positive mounts to the bottom.

The proposed cam follower should in particular consist of a lightweight material such as sheet metal. It is also conceivable, however, to create a cam follower with the described design, which is produced by casting or casting.

Short description of the drawing

Figur 1

einen Längsschnitt durch den Nockenfolger;

Figuren 2a und 2b

Unteransichten auf den Nockenfolger mit verschiedenartig gestalteten Enden;

Figur 2c

Einen nicht erfindungsgemäßen Nockenfolger und

Figuren 3a, b

Querschnitte durch den Nockenfolger im Bereich dessen Ventilschaftauflage.

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

FIG. 1

a longitudinal section through the cam follower;

FIGS. 2a and 2b

Bottom views of the cam follower with variously shaped ends;

Figure 2c

A non-inventive cam follower and

FIGS. 3a, b

Cross sections through the cam follower in the area of the valve stem support.

Detailed description of the drawing

The figures show a cam follower 1 of a valve drive of an internal combustion engine designed here as a drag lever and made of sheet metal. The cam follower 1 has two parallel side walls 3a, 3b which are connected by a transverse bar 2. In cross section, the cam follower 1 forms an upwardly open U-profile. A bottom 4 of the cam follower 1 has at one end 5 a system 6 for a gas exchange valve. The system 6 is bounded on both sides by guide cheeks 7a, 7b.

FIG. 2b discloses that the side walls 3a, 3b in the direction of one end 5 in a gradually tapered portion 9 pass. This section 9 closes, as well as in Figure 2c shown, a longitudinal portion 10 of equal width. The end 5 is thus kept much narrower than the remaining cam follower 1.

In the region of the longitudinal section 10 at one end 5, the guide cheeks 7a, 7b are applied. How out FIG. 2b As can be seen, these run indented to the side walls 3a, 3b and have a smaller thickness D _F than the side walls 3a, 3b. It is particularly advantageous if this thickness D _{F is} smaller than an average wall thickness D _{SM of} the side walls 3 a, 3 b in the region of the narrow one end 5.

• Es wird an dieser Stelle betont, daß die vorteilhafteste Ausgestaltung der Erfindung aus Figur 2b in Verbindung mit Figur 3b hervorgeht. -

The FIGS. 2a, b show against the side walls 3a, 3b indented guide cheeks 7a, 7b, whereas out Figure 2c Guide cheeks 7a, 7b emerge, which extend with their outer sides 11a, 11b, the outer surfaces 12a, 12b of the side walls 3a, 3b.

• It is emphasized at this point that the most advantageous embodiment of the invention FIG. 2b combined with FIG. 3b evident. -

From the FIGS. 3a, 3b It can be seen by those skilled in the art that the wall thickness D _{SM of} the side walls 3a, 3b, starting from end faces 8a, 8b, continuously increases in the direction of the transverse bar 2. Due to such a design specification, the end 5 of the cam follower 1 is particularly advantageous in a stamping extrusion (cold forging) finished and has excellent stiffness with very low mass and minimum moment of inertia.

The FIG. 3b disclosed as mentioned, that the guide cheeks 7a, 7b are clearly indented to the side walls 3a, 3b formed, so that at least in the region of this bottom 4 only very little space is needed.

Illustrated is a drag lever as a cam follower 1. Conceivable and provided, however, are equally swinging and rocker arms. In addition, the graphically disclosed U-profile does not have to be present for the cross-section of the cam follower 1; it may also have an H-shaped or similar profile or may merely be U-shaped.

List of reference numbers and symbols

1

cam follower

2

crossbeam

3a

Side wall

3b

Side wall

4

bottom

5

The End

6

investment

7a

guide cheek

7b

guide cheek

8a

front

8b

front

9

section

10

longitudinal section

11a

outside

11b

outside

12a

outer surface

12b

outer surface

D _SM

average wall thickness sidewalls

D _F

Thick guide cheeks

Claims (6)

1. Lever-like cam follower (1) composed of sheet metal, in particular for a valve drive of an internal combustion engine, having two parallel side walls (3a, 3b) which are connected by means of a transverse beam (2), with an underside (4) of the transverse beam (2) having, at one end (5), an abutment (6) for at least one gas exchange valve, which abutment (6) is delimited by guide cheeks (7a, 7b) which run parallel to the side walls (3a, 3b), with the side walls (3a, 3b) having a wall thickness (D_SM) which, at least in the region of the end (5), increases continuously from end sides (8a, 8b) of the side walls (3a, 3b) in the direction of the transverse beam (2), with the guide cheeks (7a, 7b) being integrally connected to the underside (4) of the transverse beam (2) and extending away from the latter, and with the outer sides (11a, 11b) of said guide cheeks (7a, 7b) being recessed considerably in relation to outer surfaces (12a, 12b) of the side walls (3a, 3b) in the region of the one end (5), with at least the guide cheeks (7a, 7b) at the one end (5) being produced in an embossing-extrusion process, characterized in that the spacing between the side walls (3a, 3b) is smaller at the one end (5) than over the rest of the extent of the cam follower (1), with the side walls (3a, 3b) having a smaller mean wall thickness (D_SM) at least in the region of the narrow end (5) than over the rest of their length, and with the side walls (3a, 3b) being bent orthogonally with respect to the transverse beam (2) before the substantial formation of the guide cheeks (7a, 7b).
2. Cam follower according to Claim 1, characterized in that a thickness (D_F) of the guide cheeks (7a, 7b) is smaller than the mean wall thickness (D_SM) in the region of the narrow one end (5).
3. Cam follower according to Claim 1, characterized in that a thickness (D_F) of the guide cheeks (7a, 7b) corresponds to the mean wall thickness (D_SM) in the region of the narrow end (5).
4. Cam follower according to Claim 1, characterized in that the narrow one end (5) extends from a gradually tapering section (9) of the cam follower (1) (figures 2b, 2c).
5. Cam follower according to Claim 1, characterized in that the narrow one end (5) ends in a longitudinal section (10) of constant width.
6. Cam follower according to Claim 5, characterized in that the guide cheeks (7a, 7b) run predominantly or entirely in the longitudinal section (10).

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