WO2010127731A1

WO2010127731A1 - System for controlling a gas exchange valve of an internal combustion engine

Info

Publication number: WO2010127731A1
Application number: PCT/EP2010/001003
Authority: WO
Inventors: Alex Meier; Franz Salzgeber; Immo Vogel; Peter Wiesner
Original assignee: Thyssenkrupp Presta Teccenter Ag
Priority date: 2009-05-02
Filing date: 2010-02-18
Publication date: 2010-11-11
Also published as: DE102009019788A1; DE102009019788B4

Abstract

The invention relates to a system for controlling a gas exchange valve of an internal combustion engine, comprising a camshaft (2) having a shaft-like carrier body (6) comprising at least one cam (4) and a cam follower (8) operatively connected to the cam (4) for transferring the cam profile. The cam follower (8) thereby has a rotatably supported rolling body (10) acting on the cam (4). According to the invention, the cam (4) has a width (b_N) that is less than the width (b_R) of the rolling body (10) of the cam follower (8) interacting with the cam (4).

Description

System for controlling a gas exchange valve of an internal combustion engine

description

The present invention relates to a system for controlling a gas exchange valve of an internal combustion engine according to the preamble of patent claim 1.

Such systems, which essentially comprise a camshaft having one or more cams and a cam follower interacting with the at least one cam, are well known in the art. The use of a drag lever which has at its the cam associated free end a rolling body (so-called. Roller cam followers) to ensure the lowest possible contact with the cam, has been known for some time. Such valve train arrangements have already proven themselves many times in the past.

The present invention is based on the object to provide a generic system, which allows a reduction of the rotating masses while maintaining the reliability.

According to the invention, this object is achieved by the totality of the features of patent claim 1. According to the invention, the cam of the camshaft has a smaller width than that with the cam co-operating rolling elements of the rocker arm. Advantageously, the width ratio between cam width and rolling body width is approximately 1: 1.2 to 1: 1.7.

In a particularly preferred embodiment of the invention, at least the cam is circumferentially chamfered on both sides (ie at the contour edges of its two lateral end faces), so that its effective contact width to the rolling body is smaller than the actual width of the cam - in particular, the effective contact width is approximately 20% smaller than the cam width. To further reduce hertzian surface pressures (between effective camming surface or parts thereof and the rolling element or parts of the rolling element), it is intended to round off the transition between the effective contact surface of the cam and the surface of the lateral chamfer and provide a predetermined radius in the transition region. This radius is advantageously dimensioned such that the straight lines, seen in cross-section, of the effective contact surface of the cam and the respective lateral chamfer surface form tangents of an imaginary inner circle. Advantageously, the radius is about 0.3 to 0.6 mm - preferably about 0.5 mm.

In order to be able to absorb the remaining hertzian surface pressures in the construction according to the invention, advantageously both the cam and the rolling bodies cooperating with the cam (at least in the area of their contact surfaces) are made of a bearing steel having an adequate hardness (about 55 HRC (hardness measurement) Rockwell)) of a bearing steel with the DIN designation 1.3505 (according to DIN (German Industrial Standard) EN ISO 683-17) after appropriate heat treatment. By means of the corresponding heat treatment it is achieved that a permissible hertzian pressure of approximately 1800 N / mm ² can be achieved.

In a particularly preferred embodiment of the invention, the camshaft according to the embodiment described in DE 41 21 951 Cl is formed. This is - in particular with regard to the manner of attachment of a forged cam on a separate camshaft body - reference is made in full to the above-mentioned document and their relevant disclosure content is included in the invention. According to DE 41 21 951 Cl a molded by forging cam, which has a particular circular or oval recess for receiving the camshaft body, frictionally mounted on the camshaft body. For this purpose, the camshaft body (shaft-like carrier body for cams) is widened at least partially in diameter in the region of its receptacle for a cam by the said surface region of the camshaft body by rolling or rolling experience a material displacement, such that in the circumferential direction of the camshaft encircling beads or webs are formed , In this case, the annular inner surface of the cam or the inner surface of the axial receptacle for the support body may be formed substantially flat or contoured. By a contoured design of the inner receiving surface - such as by at least one axially extending groove - the force or frictional engagement between the cam and camshaft body can be extended to a positive and positive fit.

Overall, the cam elements are designed according to the invention considerably narrower than cooperating with them rollers (rolling body) of the drag lever. In this case, the narrow cam elements are profiled on the running surface (chamfer on both sides - in particular with transition radius to the running surface) so that in the respective contact area to the rolling body no excessive voltage increases occur. The contact surface between the cam and rolling body (theoretically a line contact) is formed in the running surface of the rolling body. Although the Hertzian surface pressure is not significantly increased by the design according to the invention of the wear partner cam and roller body, this is more than compensated by the structural design and the design of the wear partners in a suitable rolling bearing steel (eg 100Cr6 or comparable - with hardening heat treatment) that a durable construction with extremely small rotating masses could be created. Such an embodiment of the wear partner cam and roller body allows a lightweight camshaft design and a reduction of the relevant polar mass moment of inertia to achieve a corresponding dynamic. Further advantages, features and expedient developments of the invention will become apparent from the dependent claims and the following drawings of preferred embodiments.

Show it:

1 is a fragmentary view of the system according to the invention with a camshaft and a cooperating with the cam rolling body,

Fig. 2 is a partial enlargement in the region of the contact surface between the cam and rolling body according to detail A in Fig. 1, and

Fig. 3 is a partial enlargement in the region of the contact surface between the cam and rolling body in the transition region between the effective cam contact surface and the cam chamfer surface according to detail B in FIG.

Second

Figure 1 shows the system according to the invention for controlling a gas exchange valve of an internal combustion engine in a schematic representation. The system essentially comprises a camshaft 2 with a shaft-like carrier body 6 having at least one cam 4 and a cam follower 8 operatively connected to the cam 4 for transmitting the cam contour, the cam follower 8 acting on the cam 4 via a rotatably mounted roller body 10. The preferred width ratio between cam width b _N and roller body width b _R is approximately 1: 1.2 to 1: 1.7.

To illustrate a particularly preferred embodiment of the invention, the contact area between the cam 4 and the rolling body 10 according to detail A in Fig. 1 in Figure 2 is shown. Advantageously, the cam 4 has a chamfer F _N on both sides. In this case, the chamfer F _{N is} dimensioned such that the effective cam contact surface A ^ _N (or the corresponding cam contact width b _M ) in comparison to the cam contact surface without chamfer F _N (or compared to the cam width b _N ) to about 20% is reduced. The remaining effective cam contact width bκ_ _N (which equals the effective rolling body width b 'j * is) is approximately two-thirds (2/3) of the potential of rolling elements effective tread width b ^ _R. The chamfer F _N on the cam 4 is designed in such a way that an angle α of approximately 35 ° degrees results between the chamfer surface Ap _N and the effective cam contact surface Aκ_ _N (or the roller body running surface A _K _R). In addition, the cam 4 is formed in its circumferential shape such that the transition between the chamfer surface A _F _ _N and the effective contact surface A _K _ _N over a predetermined radius r is rounded. The radius r is advantageously dimensioned in such a way that the straight lines of the contact surface A ^ _N and the chamfer surface A _F _ _N , which are seen in cross-section, form tangents of an inner circle K. In the illustrated embodiment, the rolling body 10 is provided with lateral chamfers F _R and chamfer surfaces A _{f R} , so that in comparison to the rolling body width b _R reduced rolling body tread width b ^ _ _R (and thus a reduced rolling body running surface AuO results.

(AK_N; A _K _R) in Figure 3 is a partial enlargement in the area of the contact surface is shown between the cam and rolling elements in the transition area between the effective cam contact surface A ^ _N and cam land surface AF_ _N according to detail B in FIG. 2.

LIST OF REFERENCE NUMBERS

Camshaft 2

Cam 4

Carrier body 6

Cam follower 8

Rolling body 10

Cam width b _N effective contact width

(Cam) t> KJJ

Roller body width b _R effective contact width

(Rolling body) bo

Rolling body tread width bm

Radius r

Chamfer (cam) F _N

Chamfer (rolling body) FR

Bevel surface (cam) AF_H

Bevel surface (rolling body) AF_R

Contact surface (cam) Aκ_N

Tread (rolling body) At_R

Contact surface (rolling element) A _K _R

Bevel angle α

Intersection (tangents) P

Circle K

Claims

claims:

1. System for controlling a gas exchange valve of an internal combustion engine comprising

- A camshaft (2) with a wave-like, at least one cam (4) having support body (6), and

- One with the cam (4) operatively connected to the cam contour cam follower (8), wherein the cam follower (8) via a rotatably mounted roller body (10) acts on the cam (4), characterized in that

- The cam (4) has a width (b _N ), which is smaller than the width (bg) of the cam (4) cooperating rolling body (10) of the cam follower (8).

2. System according to claim 1, characterized in that

- The ratio between the cam width (b _N ) and roll body width (b ^ is substantially in a range between 1: 1.2 to 1: 1.7.

3. System according to claim 1 or 2, characterized in that

- The cam (4) has circumferentially and on both sides a chamfer (F _N ).

4. System according to claim 3, characterized in that

- The chamfer is dimensioned such that the effective contact width (b _κ _κ) of the cam (4) is smaller by substantially twenty percent than the actual width (b _N ) of the cam (4).

5. System according to claim 3 or 4, characterized in that

- The transition between the chamfer surface (AF_ _N ) and actual contact surface (A ₁ ^ _N ) of the cam (4) over a predetermined, circumferential radius (r) is rounded.

6. System according to claim 5, characterized in that

- The radius (r) is dimensioned such that the seen in cross section in the point (P) intersecting straight lines of the contact surface (A _K _ _N ) and the chamfer surface (A _FN ) tangents of an inner circle (K) form.

7. System according to any one of the preceding claims, characterized in that

- The at least one cam (4) at least in the region of its effective contact surface (A _K _ _N ) has a hardness which is an adequate

Rolling bearing steel corresponds - in particular has a hardness of about 55 HRc.

8. System according to any one of the preceding claims, characterized in that

- The rolling body (10) at least in the region of the rolling body running surface (A _L _R) has a hardness which corresponds to an adequate bearing steel - in particular a hardness of about 55 HRc.

9. System according to any one of the preceding claims, characterized in that the at least one on the support body (6) arranged cam (4) via a non-positive or a non-positive and positive connection with the support body (6) is connected.

10. System according to claim 9, characterized in that the carrier body (6) in the region of the receptacle for a cam (4) is at least partially expanded in diameter, such that in the circumferential direction of the carrier body (6) encircling beads or webs with a Diameter greater than the diameter of the corresponding cam receiver are formed, and wherein by a lateral sliding of the cam (4) on the carrier body (6) in the region of the intended recording a frictional or force and positive connection between the cam and the carrier body (6) seen in the direction of rotation of the camshaft is achieved.