SLIDING CAM SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

Abstract

A sliding cam system for an internal combustion engine is disclosed. The sliding cam system includes a carrier shaft and an axially adjustable cam sleeve arranged on the carrier shaft. The cam sleeve is axially adjustable relative to the carrier shaft between a first axial position and a second axial position, and axially fixable in the respective axial position by a detent device. The detent device includes a first receiving groove assigned to the first axial position and a second receiving groove assigned to the second axial position. The detent device further includes a preload element disposed on the cam sleeve. The preload element preloads a detent element arranged between the carrier shaft and the cam sleeve towards the carrier shaft. The detent element is received in the first receiving groove in the first axial position and the second receiving groove in the second axial position.

Claims

1. A sliding cam system for an internal combustion engine, comprising: carrier shaft extending along an axial direction, at least one sleeve-shaped cam sleeve arranged on the carrier shaft radially outside and axially adjustable relative to the carrier shaft, the at least one sleeve-shaped cam sleeve including at least one cam profile, the carrier shaft and the at least one cam sleeve for the transmission of torque being non-rotatably connected to one another, the at least one cam sleeve being axially adjustable relative to the carrier shaft between a first axial position and at least one second axial position and axially fixable in a respective one of the first axial position and the at least one second axial position on the carrier shaft via a detent device wherein the detent device includes: a first receiving groove assigned to the first axial position and a second receiving groove assigned to the at least one second axial position, wherein the first receiving groove and the second receiving grooves are axially spaced apart from one another and each extend along an outer circumference of the carrier shaft, and a preload element disposed on the at least one cam sleeve, wherein the preload element preloads a detent element arranged between the carrier shaft and the at least one cam sleeve towards the carrier shaft, and wherein the detent element is received in the first receiving groove when the at least one cam sleeve is located in the first axial position and received in the second axial groove when the at least one cam sleeve is located in the at least one second axial position.

2. The sliding cam system according to claim 1, wherein the preload element is a detent spring arranged in a receptacle disposed on the at least one cam sleeve and exerts a preload force on the detent element.

3. The sliding cam system according to claim 1, further comprising a receptacle structured as an opening extending radially in the at least one cam sleeve and a support element received in the receptacle, wherein the preload element radially supports itself on the support element radially outside for generating a preload force.

4. The sliding cam system according to claim 3, wherein: the opening is structured as a through-bore, and the support element present in the through-bore is firmly connected to the at least one cam sleeve via a press connection and arranged fixed in place relative to the at least one cam sleeve.

5. The sliding cam system according to claim 3, wherein the support element includes an external thread, which for the radial adjustability of the support element engages in an internal thread provided on the opening formed complementarily to the external thread, such that the support element is radially adjustable relative to the at least one cam sleeve.

6. The sliding cam system according to claim 3, wherein the support element is structured as a threaded pin.

7. The sliding cam system according to claim 3, further comprising a sleeve-shaped housing delimiting a housing interior provided on the support element, wherein the preload element and the detent element are each at least partially received in the housing interior.

8. The sliding cam system according to claim 7, wherein the support element, the preload element, the detent element and the sleeve-shaped housing are provided integrally as a unit.

9. The sliding cam system according to claim 1, wherein the detent element is formed structured as a detent ball.

10. The sliding cam system according to claim 1, wherein a radius of the carrier shaft is reduced in an axial region between the two first receiving groove and the second receiving grooves.

11. The sliding cam system according to claim 1, wherein: the first receiving groove and the second receiving grooves each comprise a groove base and a first groove flank and second groove flank, wherein the respective first groove flanks have a smaller axial distance to the respective other receiving groove than the respective second groove flanks; and wherein in at least one of the first receiving groove and the second receiving groove the first groove flank and the second groove flanks are each arranged at a first acute angle and a second acute angle respectively to a radial direction, wherein a first angular value of the first acute angle is greater than a second angular value of the second acute angle.

12. The sliding cam system according to claim 1, wherein a radially measured depth of at least one of the first receiving groove and the second receiving groove amounts to maximally 10%, of a radius of the carrier shaft.

13. An internal combustion engine for a motor vehicle, comprising: at least one cylinder comprising a combustion chamber provided with an inlet valve for introducing fresh air into the combustion chamber and an exhaust valve for discharging exhaust gas out of the combustion chamber are provided, and at least one sliding cam system for controlling at least one of the inlet valve and the exhaust valve, the at least one sliding cam system including: a carrier shaft extending along an axial direction; at least one sleeve-shaped cam sleeve arranged on the carrier shaft radially outside and axially adjustable relative to the carrier shaft, the at least one sleeve-shaped cam sleeve including at least one cam profile; the carrier shaft and the at least one cam sleeve for the transmission of torque being non-rotatably connected to one another; the at least one cam sleeve being axially adjustable relative to the carrier shaft between a first axial position and at least one second axial position and axially fixable in a respective one of the first axial position and the at least one second axial position on the carrier shaft via a detent device, wherein the detent device includes: a first receiving groove assigned to the first axial position and a second receiving groove assigned to the at least one second axial position, wherein the first receiving groove and the second receiving groove are axially spaced apart from one another and each extend along an outer circumference of the carrier shaft and a preload element disposed on the at least one cam sleeve, wherein the preload element preloads a detent element arranged between the carrier shaft and the at least one cam sleeve towards the carrier shaft, and wherein the detent element is received in the first receiving groove when the at least one cam sleeve is located in the first axial position and received in the second axial groove when the at least one cam sleeve is located in the at least one second axial position.

14. The internal combustion engine according to claim 13, wherein the preload element is a detent spring arranged in a receptacle disposed on the at least one cam sleeve and exerts a preload force on the detent element.

15. The internal combustion engine according to claim 14, wherein the receptacle is structured as an opening extending radially in the at least one cam sleeve and a support element is received in the opening, wherein the detent spring radially supports itself on the support element radially outside for generating the preload force.

16. The internal combustion engine according to claim 15, wherein the support element includes an external thread that engages an internal thread provided on the opening such that the support element is radially adjustable relative to the at least one cam sleeve.

17. The internal combustion engine according to claim 15, further comprising a sleeve-shaped housing delimiting a housing interior provided on the support element, wherein the detent spring and the detent element are each at least partially received in the housing interior.

18. The internal combustion engine according to claim 13, wherein the detent element is structured as a detent ball.

19. The internal combustion engine according to claim 13, wherein a radius of the carrier shaft is reduced in an axial region between the first receiving groove and the second receiving groove.

20. The internal combustion engine according to claim 13, wherein a radially measured depth of the first receiving groove and the second receiving groove amounts to 10% or less of a radius of the carrier shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] It shows, in each case schematically:

[0028] FIG. 1 an example of a sliding cam system according to the invention in a longitudinal section along an axial direction of the carrier shaft,

[0029] FIG. 2 a further development of the example of FIG. 1, in which different components of the detent device that is substantial for the invention are formed as a unit in contrast with the example of FIG. 1,

[0030] FIG. 3 a detail representation of the sliding cam system of FIGS. 1 and 2 in the region of the two receiving grooves.

DETAILED DESCRIPTION

[0031] FIG. 1 illustrates an example of a sliding cam system 1 according to the invention in a longitudinal section. The sliding cam system 1 includes a carrier shaft 2 extending along an axial direction A on which, radially outside and axially adjustable relative to the same, a sleeve-shaped cam sleeve 3 comprising a cam profile 4 is arranged. Thus, the cam sleeve 3 is formed as a hollow shaft whose inner circumference 24 lies against the outer circumference 7 of the carrier shaft 2. Together, the carrier shaft 2 and the cam sleeve 3 form a camshaft.

[0032] The cam sleeve 3 extends along the axial direction A. The carrier shaft 2 and cam sleeve 3 are arranged coaxially to one another. The axial direction A extends along a common centre longitudinal axis M of carrier shaft 2 and cam sleeve 3. A radial direction R extends perpendicularly away from the centre longitudinal axis M and also away perpendicularly to the axial direction A. A circumferential direction U runs perpendicularly both to the radial direction R and also to the axial direction A round about the centre longitudinal axis M.

[0033] FIG. 1 shows the sliding cam system 1 in a longitudinal section along the axial direction A. Accordingly, for transmitting a torque from the carrier shaft 2 to the cam sleeve 3 the carrier shaft 2 and the cam sleeve 3 are non-rotatably connected to one another. The non-rotatable connection can take place for example, with a suitable tooth geometry, which on the inner circumference of the cam sleeve 3 and on the outer circumference of the carrier shaft 2 comprises projecting teeth in each case (not shown in the figures), which for transmitting a torque mesh with one another.

[0034] Irrespective of such a non-rotatable connection, the cam sleeve 3 is adjustable relative to the carrier shaft 2 along the axial direction A between a first and a second axial position AP1, AP2. In this way, the two cam profiles 3a, 3b formed on the cam sleeve 3 radially outside can also be axially adjusted. Apart from this, the cam sleeve 3 can be axially fixed in the respective axial position AP1, AP2 on the carrier shaft 3 by means of a detent device 5. In the example, the cam sleeve 3 has two different cam profiles 3a, 3b which are moulded on the cam sleeve 3 radially outside next to one another along the axial direction A. When the cam sleeve 3 according to the exemplary embodiment of the figures is located in the first axial position AP1, the first cam profile 3a can interact with a valve of an internal combustion engine not shown in more detail in the figures. When the cam sleeve is located in the second axial position AP2, the second cam profile 3b can interact with the valve of the internal combustion engine. Similar applies analogously also when three or more cam profiles and thus three or more axial positions of the cam sleeve 3 are provided.

[0035] Obviously, a larger number of such different cam profiles can also be provided in further developments of the example, wherein each cam profile is then assigned a certain axial position.

[0036] In the example of the figures, a first receiving groove 6a and a second receiving groove 6b spaced apart from one another are arranged on the outer circumference 7 of the carrier shaft 2 along the axial direction A as part of the detent device 5. Both run completely round about the outer circumference 7 of the carrier shaft 2 along the circumferential direction U. The first receiving groove 6a serves for fixing the cam sleeve 3 in the first axial position AP1. The second receiving groove 6b serves for fixing the cam sleeve 3 in the second axial position AP2. To this end, the detent device 5 includes a preload element 8 arranged on or in the cam sleeve 3, which preloads a detent element 11 arranged between carrier shaft 2 and cam sleeve 3 towards the carrier shaft 2, so that the detent element 11 is received in the first receiving groove 6a when the cam sleeve 3 is located in the first axial position AP1 and received in the second receiving groove 6b when the cam sleeve 3 is located in the second axial position AP2. The preload element 8 can be a detent spring 9 which is arranged in a receptacle 10 present in the cam sleeve 3 and exerts a preload force on the detent element 11. As shown, the detent element 11 can be formed as a detent ball 21.

[0037] The receptacle 10 in the exemplary scenario is formed by an opening 12 extending along the radial direction R from the inner circumference 24 to the outer circumference 25 of the cam sleeve 3. In the receptacle 10 or in the opening, a support element 13 is arranged on which the preload element 8 supports itself radially outside, so that it can exert the desired preload force on the detent element 11 radially inside.

[0038] In the example of FIG. 1, the support element 13 can be radially adjusted relative to the cam sleeve 3 along the radial direction R. To this end, the support element 13 comprises an external thread 16, which for the radial adjustability of the support element 13 engages in an internal thread 17 provided on the opening 12 formed complementarily to the external thread 16. Thus, the support element 13 can be moved along the radial direction R in the manner of a threaded pin 18.

[0039] FIG. 2 illustrates a further-development variant of the example of FIG. 1. In the example of FIG. 2, the support element 13 is followed radially inside by a sleeve-shaped housing 19 delimiting a housing interior 20. In the housing interior 20, the preload element 8 and the detent element 11 are at least partially received. Preferably, the sleeve-shaped housing 19 is dimensioned with respect to its diameter and matched to the diameter of the detent element 11 or the detent ball 21 so that the preload element 8, in particular the detent spring 9, is completely arranged in the housing interior 20 and the detent element 11 or detent ball 21 is arranged in the region of an opening edge 26, which surrounds a sleeve opening 27 of the sleeve-shaped housing 19 facing the carrier shaft 2. In this way, the guidance of the detent element 11 or of the detent ball 21 along the axial direction R is improved.

[0040] In a further development of the example of FIG. 2, the said elements, i.e. the support element 13, the preload element 8, the detent element 11 and also the sleeve-shaped housing 19 can be formed integrally and thus as a unit. Such a unit can be referred to as a “screwed-in resilient integral thrust piece”.

[0041] As is evident from FIG. 3, a radius r of the carrier shaft 3 can be reduced in an axial region 22 between the two receiving grooves 6a, 6b. This facilitates the axial adjusting movement of the cam sleeve 3 because of the intermediate space 28 forming in the axial region 22 between the carrier shaft 2 and the cam sleeve 3.

[0042] In a simplified variant of the example of the FIGS. 1 and 2, the opening 12 can be formed as a through-bore, wherein the support element 13 arranged in the through-bore is firmly connected to the cam sleeve 3 by means of a press connection, in particular by means of a press fit, and thus arranged fixed in position relative to the same.

[0043] FIG. 3 is a detail view of the first receiving groove 6 both according to the example of FIG. 1 and also according to the example of FIG. 2. According to the FIGS. 1 to 3, the two receiving grooves 6a, 6b can each comprise a groove base 23c and a first and a second groove flank 23a, 23b. Here, the respective first groove flank 23a is arranged at a smaller axial distance to the respective other receiving groove 6b, 6a than the respective second groove flank 23b.

[0044] According to FIG. 3, the two groove flanks 23a, 23b in the first receiving groove 6a, 6b, preferentially in both receiving grooves 6a, 6b, can each be arranged at a first or second acute angle α1, α2 to the radial direction R. As is clearly shown in FIG. 3, a first angular value w1 of the first acute angle al is greater than a second angular value w2 of the second acute angle α2. This facilitates the axial movement of the detent element 11 or of the detent ball 21 out of the respective first or second receiving groove 6a, 6b towards the other, i.e. second or first receiving groove 6b, 6a respectively. In the example, a depth T of the first receiving groove 6a measured along the radial direction R amounts to maximally 10%, preferentially maximally 8% of the radius r of the carrier shaft 2.

[0045] The above explanations regarding the configuration of the first receiving groove 6a apply mutatis mutandis also to the second receiving groove 6b.