VALVE TRAIN HAVING A SLIDING CAM ELEMENT

Abstract

A valve drive may include a sliding cam element that is held on a carrier shaft so as to be axially displaceable along an axis of rotation of the carrier shaft. The sliding cam element may include at least one cam profile group with cam profile sections of mutually different form. The valve drive may further include a pick-off element by way of which a control movement can be picked off from the cam profile sections and transmitted to a valve. The sliding cam element may also include a second cam profile group that is similar or identical to the first cam profile group and, which for the joint control of one valve, may interact with the pick-off element.

Claims

1.-10. (canceled)

11. A valve drive comprising: a sliding cam element that is disposed on a carrier shaft so as to be axially displaceable along an axis of rotation of the carrier shaft, wherein the sliding cam includes a first cam profile group with cam profile sections of mutually different form and a second cam profile group with cam profile sections of mutually different form, wherein the cam profile sections of the first cam profile group are the same as the cam profile sections of the second cam profile group; and a pick-off element by way of which a control movement is picked off from the cam profile sections and transmitted to a valve, wherein the two cam profile groups interact with the pick-off element to jointly control the valve.

12. The valve drive of claim 11 wherein the first and second cam profile groups are adjacent and adjoin one another on the sliding cam element.

13. The valve drive of claim 11 wherein a first roller of the pick-off element interacts with the cam profile sections of the first cam profile group and a second roller of the pick-off element interacts with the cam profile sections of the second cam profile group.

14. The valve drive of claim 13 wherein the first and second rollers are disposed along a common roller axis.

15. The valve drive of claim 13 wherein a diameter of the first roller is equal to a diameter of the second roller.

16. The valve drive of claim 13 wherein the cam profile sections have mutually identical cam contours.

17. The valve drive of claim 13 wherein the pick-off element includes an intermediate space between the first and second rollers, wherein a size of the intermediate space corresponds at least to a width of one of the cam profile sections or of two of the cam profile sections of one of the cam profile groups.

18. The valve drive of claim 11 wherein the cam profile sections include a common cam base circle section that has a diameter that is constant over a width of the sliding cam element.

19. The valve drive of claim 11 wherein the pick-off element is configured as a rocker lever.

20. The valve drive of claim 11 wherein the sliding cam element is formed in one piece with the first and second cam profile groups.

21. The valve drive of claim 11 wherein the sliding cam element is integral with the first and second cam profile groups.

22. A valve drive comprising: a sliding cam element disposed on a carrier shaft and axially displaceable along an axis of rotation of the carrier shaft, wherein the sliding cam includes a first cam profile group having different cam profile sections; and a pick-off element by way of which a control movement is transferred from the cam profile sections to a valve, wherein the first cam profile group interacts with the pick-off element to control the valve.

23. The valve of claim 22 further comprising a second cam profile group having different cam profile sections, wherein the cam profile sections of the first cam profile group are the same as the cam profile sections of the second cam profile group, wherein the first and second cam profile groups interact with the pick-off element to jointly control the valve.

24. The valve drive of claim 22 wherein the pick-off element is configured as a rocker lever.

25. The valve drive of claim 22 wherein the sliding cam element is integral with the first cam profile group.

Description

PREFERRED EXEMPLARY EMBODIMENT OF THE INVENTION

[0016] Further measures which improve the invention will be presented in more detail below in conjunction with the description of a preferred exemplary embodiment of the invention on the basis of the figures, in which:

[0017] FIG. 1 shows a side view of a valve drive having the features of the present invention,

[0018] FIG. 2 shows a perspective view of the valve drive as per FIG. 1, and

[0019] FIG. 3 shows a further side view of the valve drive as per FIGS. 1 and 2.

[0020] FIGS. 1, 2 and 3 show the valve drive 1 with the features essential to the invention in second side views and in a perspective view. The valve drive 1 has a sliding cam element 10 which is formed in one piece and which is held on a carrier shaft 11 so as to be axially displaceable in an axis of rotation 12. The carrier shaft 11 is shown only in sections, and means (not shown in any more detail) may be provided on the sliding cam element 10 for the purposes of displacing said sliding cam element in the direction of the axis of rotation.

[0021] Two cam profile groups 13 of mutually identical form are formed on the sliding cam element 10. The cam profile groups 13 have, by way of example, three cam profile sections 14, wherein one cam profile section 14 is in the form of a zero-lift cam, and two further cam profile sections 14 are formed with different lift heights. Here, the cam profile sections 14 adjoin one another in the axial direction.

[0022] A pick-off element 15 interacts with the cam profile groups 13, which pick-off element transmits the lift information of the cam profile groups 13 to a valve 16. The valve 16 is furthermore shown as having a valve spring 21, and on that side of the pick-off element 15 which is situated opposite the valve 16, there is situated a support element 20 which can serve as a valve play compensation element and on which the pick-off element 15 is supported.

[0023] In the exemplary embodiment shown, the pick-off element 15 is in the form of a roller-type rocker lever with rollers 17 which are held on the main body of the pick-off element 15 in a common roller axis 18. The rollers 17 are held on the pick-off element 15 so as to be spaced apart from one another, and here, the spacing corresponds to the spacing of two cam profile sections 14 of identical form from the respective cam profile groups 13 of the sliding cam element 10. Thus, a twin contact configuration between the pick-off element 15 and the sliding cam element 10 is realized.

[0024] The cam profile sections 14 of the cam profile groups 13 are formed with a width B which is smaller than a required width of cam profile sections 14 if these form, with one of the two rollers 17, the pick-off contact for the control of a valve 16. For example, the width B of the cam profile sections 14 may be approximately half the magnitude of a width of cam profile sections which form an individual contact point with a pick-off element 15. The rollers 17, too, may have a width approximately half the magnitude of a width that would be required if only one roller 17 of a pick-off element 15 were in contact with a cam profile section 14 and picked off a lift movement therefrom.

[0025] Although the sliding cam element 10 has an overall width substantially equal to an overall width of a sliding cam element 10 with cam profile groups 13 of conventional form, the required axial displacement of the sliding cam element 10 in the direction of the axis of rotation is however reduced, because the cam profile sections 14 are narrower, and thus the travel in the direction of the axis of rotation by which the sliding cam element 10 must be displaced in order to perform a changeover of the pick-off of the rollers 17 between different cam profile sections 14 is reduced.

[0026] The actuation forces of the pick-off element 15 that are generated by the cam profiles of the cam profile sections 14 are divided equally between cam profile sections 14 which are of mutually identical form and which are in contact with the two rollers 17. Thus, a line load is generated at the contact line between the rollers 17 and the cam profile sections 14, which line load is of the same magnitude as if only one roller 17 were of relatively wide form and interacted with a single cam profile section 14 of an individual cam contour.

[0027] Owing to the relatively short axial travel for the adjustment of the sliding cam element 10, a changeover of cam profile sections 14 in contact with the roller 17 can be performed more quickly, wherein the changeover must always be performed when the roller 17 is in contact with the cam base circle section 19, which is provided on that side of the sliding cam element 10 which is situated opposite the cam profile groups 13. Thus, the sliding cam element 10 can be adjusted even at relatively high rotational speeds of the valve drive 1, for example above 4000 rpm.

[0028] The invention is not restricted in terms of its embodiment to the preferred exemplary embodiment specified above. Rather, numerous variants are conceivable which make use of the presented solution even in fundamentally different types of embodiment. All of the features and/or advantages which emerge from the claims, from the description or from the drawings, including design details or spatial arrangements, may be essential to the invention both individually and in a wide variety of combinations.

LIST OF REFERENCE DESIGNATIONS

[0029] 1 Valve drive [0030] 10 Sliding cam element [0031] Carrier shaft [0032] 12 Axis of rotation [0033] 13 Cam profile group [0034] 14 Cam profile section [0035] 15 Pick-off element [0036] 16 Valve [0037] 17 Roller [0038] 18 Roller axis [0039] 19 Cam base circle section [0040] 20 Support element [0041] 21 Valve spring [0042] B Width