Valve train for an internal combustion engine

Abstract

A valve train for an internal combustion engine may include a cam shaft and a cam follower. The valve train may also include a first cam arranged on the cam shaft for conjoined rotation. The valve train may further include a second cam arranged on the cam shaft for conjoined rotation and axially adjacent to the first cam. The cam follower may be axially adjustable between a first position, in which the cam follower is drive-connected to the first cam, and a second position, in which the cam follower is drive-connected to the second cam. The cam follower may include a mechanical adjustment device interacting with the cam shaft for axially adjusting the cam follower between the first position and the second position.

Claims

1. A valve train for an internal combustion engine, comprising: a cam shaft; a cam follower; a first cam arranged on the cam shaft for conjoined rotation; and a second cam arranged on the cam shaft for conjoined rotation and axially adjacent to the first cam; the cam follower axially adjustable between a follower first position, where the cam follower is drive-connected to the first cam, and a follower second position, where the cam follower is drive-connected to the second cam; the cam follower including a mechanical adjustment device interacting with the cam shaft for axially adjusting the cam follower between the follower first position and the follower second position; the mechanical adjustment device including an adjustable first mechanical engagement element comprising a pin, the adjustable first mechanical engagement element configured to interact with a first slide guide disposed on the cam shaft to axially adjust the cam follower from the follower first position to the follower second position; the mechanical adjustment device further including an adjustable second mechanical engagement element comprising a pin, the adjustable second mechanical engagement element configured to interact with a second slide guide disposed on the cam shaft to axially adjust the cam follower from the follower second position to the follower first position; the mechanical adjustment device further including at least one of a first linear actuator and a second linear actuator; the first linear actuator of the at least one of the first linear actuator and the second linear actuator structured and arranged to adjust the first mechanical engagement element between a first element first position, where the first mechanical engagement element engages into the first slide guide, and a first element second position, where the first mechanical engagement element does not engage into the first slide guide; and the second linear actuator of the at least one of the first linear actuator and the second linear actuator structured and arranged to adjust the second mechanical engagement element between a second element first position, where the second mechanical engagement element engages into the second slide guide, and a second element second position, where the second mechanical engagement element does not engage into the second slide guide.

2. The valve train according to claim 1, wherein: the first linear actuator of the at least one of the first linear actuator and the second linear actuator is adjustable between a first-inactive position and a first-active position, wherein the first linear actuator is not in contact with the first mechanical engagement element when in the first-inactive position, and wherein the first linear actuator adjusts the first mechanical engagement element through mechanical contact from the first element second position into the first element first position when the first linear actuator is adjusted from the first-inactive position into the first-active position; and the second linear actuator of the at least one of the first linear actuator and the second linear actuator is adjustable between a second-inactive position and a second-active position, wherein the second linear actuator is not in contact with the second mechanical engagement element when in the second-inactive position, and wherein the second linear actuator adjusts the second mechanical engagement element through mechanical contact from the second element second position into the second element first position when the second linear actuator is adjusted from the second-inactive position into the second-active position.

3. The valve train according to claim 2, wherein at least one of: the first mechanical engagement element is adjusted from the first element first position into the first element second position by a stroke movement of the cam follower; and the second mechanical engagement element is adjusted from the second element first position into the second element second position by a stroke movement of the cam follower.

4. The valve train according to claim 2, further comprising an electronic controller configured to adjust the first linear actuator between the first-active position and the first-inactive position and the second linear actuator between the second-active position and the second-inactive position, wherein the first linear actuator and the second linear actuator are electrically driven actuators.

5. The valve train according to claim 1, wherein: the first linear actuator of the at least one of the first linear actuator and the second linear actuator includes a linearly adjustable first control element having a face side that presses against a face side of the first mechanical engagement element facing the first control element when the first mechanical engagement element engages into the first slide guide; and the second linear actuator of the at least one of the first linear actuator and the second linear actuator includes a linearly adjustable second control element having a face side that presses against a face side of the second mechanical engagement element facing the second control element when the second mechanical engagement element engages into the second slide guide.

6. The valve train according to claim 5, wherein at least one of: the first linear actuator includes a first actuator housing, the first control element projecting from the first actuator housing toward the first mechanical engagement element, and wherein the first control element is linearly adjustable relative to the first actuator housing in a direction of the first mechanical engagement element; and the second linear actuator includes a second actuator housing, the second control element projecting from the second actuator housing toward the second mechanical engagement element, and wherein the second control element is linearly adjustable relative to the second actuator housing in a direction of the second mechanical engagement element.

7. The valve train according to claim 1, wherein the first slide guide and the second slide guide are arranged on a same axial side of a common slide body relative to the first cam and the second cam.

8. The valve train according to claim 1, wherein the cam follower further includes a cam follower fixing device for detachably fixing the cam follower in at least one of the follower first position and the follower second position, wherein the cam follower fixing device includes a spring-loaded cam follower fixing element engaging into a follower first mount disposed on the cam follower in the follower first position and engaging into a follower second mount disposed on the cam follower in the follower second position.

9. The valve train according to claim 8, wherein the follower first mount is a first circumferential groove disposed on a circumferential side of the cam follower, and the follower second mount is a second circumferential groove disposed on the circumferential side at an axial distance from the first circumferential groove.

10. The valve train according to claim 1, wherein: the cam follower further includes at least one engagement element fixing device for detachably fixing at least one of i) the first mechanical engagement element in at least one of the first element first position and the first element second position, and ii) the second mechanical engagement element in at least one of the second element first position and the second element second position; the at least one engagement element fixing device includes a spring-loaded fixing element engaging an element first mount when at least one of i) the first mechanical engagement element is in the first element first position and ii) the second mechanical engagement element is in the second element first position, and engaging an element second mount when at least one of i) the first mechanical engagement element is in the first element second position and ii) the second mechanical engagement element is in the second element second position; and the element first mount and the element second mount are disposed on at least one of the first mechanical engagement element and the second mechanical engagement element.

11. The valve train according to claim 10, wherein at least one of the first mechanical engagement element and the second mechanical engagement element has an elongated base body, wherein the element first mount is a first circumferential groove and the element second mount is a second circumferential groove, the first circumferential groove and the second circumferential groove arranged an axial distance from one another on a circumferential side of the base body.

12. The valve train according to claim 1, wherein the mechanical adjustment device does not include hydraulic components or pneumatic components.

13. The valve train according to claim 1, wherein one of the first cam and the second cam is configured as a base circle without a cam stroke.

14. The valve train according to claim 1, wherein the mechanical adjustment device includes both of the first linear actuator and the second linear actuator.

15. An internal combustion engine, comprising: a valve train including: a cam shaft; a first cam arranged on the cam shaft for conjoined rotation; a second cam arranged on the cam shaft for conjoined rotation and axially adjacent to the first cam; a cam follower including a mechanical adjustment device interacting with the cam shaft for axially adjusting the cam follower between a follower first position, where the cam follower is drive-connected to the first cam, and a follower second position, where the cam follower is drive-connected to the second cam; the mechanical adjustment device including at least one adjustable mechanical engagement element comprising a pin via which the mechanical adjustment device interacts with the cam shaft and adjusts the cam follower; the cam follower further including a cam follower fixing device for detachably fixing the cam follower in at least one of the follower first position and the follower second position; and wherein the cam follower fixing device includes a spring-loaded cam follower fixing element engaging into a follower first mount disposed on the cam follower in the follower first position and engaging into a follower second mount disposed on the cam follower in the follower second position.

16. The valve train according to claim 15, wherein: the at least one mechanical engagement element includes an adjustable first mechanical engagement element comprising a pin, the adjustable first mechanical engagement element configured to interact with a first slide guide disposed on the cam shaft to axially adjust the cam follower from the follower first position to the follower second position; and the at least one mechanical engagement element further includes an adjustable second mechanical engagement element comprising a pin, the second mechanical engagement element configured to interact with a second slide guide disposed on the cam shaft to axially adjust the cam follower from the follower second position to the follower first position.

17. The valve train according to claim 16, wherein: the mechanical adjustment device further includes a first linear actuator for adjusting the first mechanical engagement element between a first element first position, where the first mechanical engagement element engages into the first slide guide, and a first element second position, where the first mechanical engagement element does not engage into the first slide guide; and the mechanical adjustment device further includes a second linear actuator for adjusting the second mechanical engagement element between a second element first position, where the second mechanical engagement element engages into the second slide guide, and a second element second position, where the second mechanical engagement element does not engage into the second slide guide.

18. The valve train according to claim 17, wherein: the first linear actuator is adjustable between a first-inactive position and a first-active position, wherein the first linear actuator is not in contact with the first mechanical engagement element when in the first-inactive position, and wherein the first linear actuator adjusts the first mechanical engagement element through mechanical contact from the first element second position into the first element first position when the first linear actuator is adjusted from the first-inactive position into the first-active position; and the second linear actuator is adjustable between a second-inactive position and a second-active position, wherein the second linear actuator is not in contact with the second mechanical engagement element when in the second-inactive position, and wherein the second linear actuator adjusts the second mechanical engagement element through mechanical contact from the second element second position into the second element first position when the second linear actuator is adjusted from the second-inactive position into the second-active position.

19. The valve train according to claim 18, wherein at least one of: the first mechanical engagement element is adjusted from the first element first position into the first element second position by a stroke movement of the cam follower; and the second mechanical engagement element is adjusted from the second element first position into the second element second position by a stroke movement of the cam follower.

20. A valve train for an internal combustion engine, comprising: a cam shaft; a first cam arranged on the cam shaft for conjoined rotation; a second cam arranged on the cam shaft for conjoined rotation and axially adjacent to the first cam; a cam follower including a mechanical adjustment device interacting with the cam shaft for axially adjusting the cam follower between a follower first position, where the cam follower is drive-connected to the first cam, and a follower second position, where the cam follower is drive-connected to the second cam; a common slide body disposed on the cam shaft to axially adjust the cam follower between the follower first position and the follower second position, the common slide body including a first slide guide and a second slide guide arranged on a same axial side of the common slide body with regard to the first cam and the second cam; the mechanical adjustment device interacting with the cam shaft and adjusting the cam follower via at least one adjustable mechanical engagement element structured as a pin engaging in at least one of the first slide guide and the second slide guide; wherein the cam follower further includes a cam follower fixing device for detachably fixing the cam follower in at least one of the follower first position and the follower second position, the cam follower fixing device including a spring-loaded cam follower fixing element engaging into a mount provided on the cam follower when the cam follower is in at least one of the follower first position and the follower second position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There are shown, respectively diagrammatically:

(2) FIG. 1 an example of a valve train according to the invention, with a cam shaft which is arranged in a first axial position,

(3) FIG. 2 the valve train of FIG. 1 with the cam shaft in a second position, displaced axially with respect to the first axial position,

(4) FIG. 3 a variant of the valve train of FIGS. 1 and 2 with two slide guides arranged on a common slide body.

DETAILED DESCRIPTION

(5) FIGS. 1 and 2 illustrate in a diagrammatic representation an example of a valve train 1 according to the invention. The valve train 1 comprises a cam shaft 2 and a cam follower 3. A first cam 4a is mounted for conjoined rotation on the cam shaft 2. A second cam 4b is arranged axially adjacent to the first cam 4a on the cam shaft 2, likewise for conjoined rotation thereto.

(6) In the example of the figures, the first cam 4a is configured as a base circle without a cam stroke. This permits the use of the valve train 1 in an internal combustion engine with a disengageable cylinder.

(7) The cam follower 3 is adjustable along an axial direction A between a first position, in which it is drive-connected to the first cam 4a, and a second position, in which it is drive-connected to the second cam 4b. FIG. 1 shows the cam follower 3 in said first position, FIG. 2 shows the cam follower 3 in its second position. The cam follower 3 can have a cylindrically configured cam follower base body 5, on the circumferential side of which a cam follower roller 6, configured hollow-cylindrically, is rotatably mounted. The cam follower base body 5 is also known to the relevant specialist in the art under the designation bolt or displacement axis. Via the cam follower roller 6, the drive connection of the two cams 4a, 4b to the cam follower 3 takes place in a known manner. Here, the rotational movement of the cam shaft 2 by means of the cams 4a, 4b is converted into a linear movement of the cam follower 3.

(8) In the first position of the cam follower 3, shown in FIG. 1, the cam follower roller 6 is coupled with the first cam 4a, in FIG. 2 with the second cam 4b. The cam follower roller 6 actuates (not shown) via a suitably configured mechanical coupling device, in particular in the manner of a control element, a valve for adjusting between an open and a closed state. Practical technical realization possibilities of such a coupling are not part of the present invention, but are known to the relevant specialist in the art from the prior art in various forms, so that a more detailed explanation in this respect can be dispensed with.

(9) The cam follower 3 of FIG. 1 has a mechanical adjustment device 7, interacting with the cam shaft 2, for the axial adjustment of the cam follower 3 between the first and the second position. The mechanical adjustment device 7 comprises, for this, a first adjustable mechanical engagement element 8a. For the axial adjusting of the cam follower 3 from the first position shown in FIG. 1 into the second position, the first mechanical engagement element 8a interacts with a first slide guide 9a present on the cam shaft 3. In an analogous manner, the mechanical adjustment device 7 has an adjustable second mechanical engagement element 8b. For the axial adjusting of the cam follower 3 from its second into the first position, the second engagement element 8b interacts with a second slide guide 9b present on the cam shaft 3.

(10) The mechanical adjustment device 7 further comprises a first actuator 10a, by means of which the first engagement element 8a is adjustable between a first position, shown in FIG. 1, in which it engages into the first slide guide 9a, and a second position, shown in FIG. 2, in which it does not engage into the first slide guide 9a. The mechanical adjustment device 7 also comprises a second actuator 10b, by means of which the second engagement element 8b is adjustable between a first position, in which it engages into the second slide guide 9b, and a second position, in which it does not engage into said second slide guide 9b. The mechanical adjustment device 7 comprises no hydraulic or pneumatic components.

(11) The first actuator 10a is adjustable between an inactive position and an active position. For this purpose, the two actuators 10a, 10b can be configured as linearly adjustable, electrically driven actuators. The mechanical adjustment device 7 is realized in this case as an electromechanical adjustment device. In other words, electrically driven actuators 10a, 10b are included here by the term mechanical adjustment device 7.

(12) The two actuators 10a, 10b are controllable by a control device 11 of the valve train 1 for adjusting between their active position and their inactive position. This adjustability is realized such that the first actuator 10a in the inactive position is out of contact with the first engagement element 8a. In the course of an adjusting from its inactive position into its active position, the first actuator 10a adjusts the first engagement element 8a through mechanical contact from its second into its first position.

(13) The adjusting of the first engagement element 8a from the first into the second position can preferably be brought about by means of the stroke movement of the cam follower 3, in particular by means of the cam follower base body 5. Here, the cam follower 3 is moved through the stroke movement brought about by the first or second cam 4a, 4b in the direction of the first actuator 10a. If it is in its active position, then through the stroke movement of the cam follower 3 and thereby of the first engagement element 8a, this is pressed against the first actuator 10a and is adjusted by it into its second position.

(14) In this state, the first engagement element 8a engages into the first slide guide 9a, so that the cam follower 3, owing to the rotational movement of the cam shaft 2, by means of the first slide guide 9a arranged thereon, is moved axially from its first into the second position. The second actuator 10b is also adjustable between an inactive position and an active position. This adjustability is realized such that the second actuator 10b in the inactive position is out of contact with the second engagement element 8b. In the course of an adjusting from its inactive position into its active position, the second actuator 10b adjusts the second engagement element 8b through mechanical contact from its second into its first position.

(15) The adjusting of the second engagement element 8b from the first into the second position is also preferably brought about by means of the stroke movement of the cam follower 3, in particular by means of the cam follower base body 5. Here, the cam follower 3 is moved through the stroke movement brought about by the first or second cam 4a, 4b in the direction of the second actuator 8b. When the latter is situated in its active position, then through the stroke movement of the cam follower 3 and thereby of the second engagement element 8b, the latter is pressed against the second actuator 10b and therefore is adjusted by it into its second position.

(16) In this state, the second engagement element 8b engages into the second slide guide 9b, so that the cam follower 3, owing to the rotational movement of the cam shaft 2, is moved by means of the second slide guide 9a arranged thereon axially from its second into the first position.

(17) The first actuator 10a has a linearly adjustable (cf. arrow 15a) first control element 12a. The latter can project partially out from a first housing 16a of the first actuator 10a and can be arranged so as to be linearly adjustable relative thereto. A face side 13a of the first control element 12a, facing the first engagement element 8a, which can be configured in a pin- or bolt-like manner, presses on moving of the first engagement element 8a into the first slide guide 9a against a face side 14a of the first engagement element 8a lying opposite the first control element 12a. The second actuator 10b has a linearly adjustable (cf. arrow 15b) second control element 12b. The latter can project partially out from a second housing 16b of the second actuator 10b and can be arranged so as to be linearly adjustable relative thereto. A face side 13b of the second control element 12b, facing the second engagement element 8b, which can be configured in a pin- or bolt-like manner, presses on moving of the second engagement element 8b into the second slide guide 9b against a face side 14b of the second engagement element 8b lying opposite the second control element 12b.

(18) As the illustration of FIG. 2 shows, the cam follower 3 also has a cam follower fixing device 17 for the detachable fixing of the cam follower 3 in the first or second position. The cam follower fixing device 17 comprises a spring-loaded cam follower fixing element 18. The cam follower fixing element 18 engages in the first position of the cam follower 3 into a first mount 19a provided on the cam follower 3, and in the second position of the cam follower 3 engages into a second mount 19b provided on the cam follower 3. Preferably, the first mount 19a is realized, as illustrated in FIG. 2, as a first circumferential groove 20a, which is arranged on a circumferential side 21 of the cam follower 3. The second mount is realized accordingly as a second circumferential groove 20b arranged axially at a distance on the circumferential side 21.

(19) As FIGS. 1 and 2 clearly show, the cam follower 3 has for the two engagement elements 8a, 8b, preferably for both engagement elements 8a, 8b, respectively a first or respectively second engagement element fixing device 22a, 22b for the detachable fixing of the first or respectively second engagement element 8a, 8b in the first or second position. As can be seen, the two engagement element fixing devices 22a, 22b have respectively a spring-loaded fixing element 23a, 23b, which in the first position of the respective engagement element 8a, 8b is received in a first mount 24a, 24b provided on the respective engagement element 8a, 8b. In the second position of the cam follower, the fixing element 23a, 23b is received in a second mount 25a, 25b provided on the cam follower. The first and the second engagement element 8a, 8b have respectively a base body 29a, 29b configured in a bolt- or pin-like manner. On a circumferential side of the base body 29a, 29b the first mount 24a, 24b is configured as a first circumferential groove 27a, 27b, and the second mount 25a, 25b as a second circumferential groove 28a, 28b arranged at a distance on the circumferential side.

(20) With the aid of the illustration of FIGS. 1 and two, an adjusting of the cam follower 3 from the first into the second position is explained below. In the scenario of FIG. 1, the cam follower 3 is situated in the first position, in which its cam follower roller 6 is drive-connected to the first cam 4a.

(21) If an adjustment of the cam follower 2 from its first into its second axial position is to take place, then the first engagement element 8a of the mechanical adjustment device 7, as shown in FIG. 1, is brought into engagement with the first slide guide 9a. This takes place by means of the first electrical actuator 10a.

(22) The first actuator 10a is, as already explained, adjustable between an inactive position shown in FIG. 1 and an active position indicated in dashed lines in FIG. 1. In the inactive position, the first actuator 10a is mechanically out of contact with the first engagement element 8a. In the course of an adjusting from its inactive position into its active position, the first actuator 10a adjusts the first engagement element 8a through mechanical contact from its second into its first position. In the first position, the first engagement element 8a engages into the first slide guide 9a (cf. FIG. 1), so that the cam follower 3 is moved by the rotational movement of the cam shaft 2 by means of the first slide guide 9a axially from its first into its second position, which is illustrated in FIG. 2. After the bringing into engagement of the first engagement element 8a with the first slide guide 9a, the first actuator 10a can be moved back by the control device 11 into its inactive position again.

(23) The first slide guide 9a can just as the second slide guide 9b have a ramp structure, not shown in the figures, such that the first engagement element 8a is brought out of engagement with the first slide guide as soon as the cam follower 3 has reached the second axial position. In this second position, the second cam 4b is in drive connection with the cam follower roller 6. The adjusting of the cam follower 3 from the second position back into the first position can take place by means of the second actuator 10b, the second engagement element 8b and the second slide guide 9b in an analogous manner to the previously explained transition from the first into the second position of the cam follower 3.

(24) In FIG. 3, a variant of the example of FIGS. 1 and 2 is shown. The valve train 1 of FIG. 3 differs from that of FIGS. 1 and 2 in that the first and second slide guide 9a, 9b are constructed relative to the two cams 4a, 4b axially on the same side in a common slide body 26. It is clear that a change to the axial arrangement of the two engagement elements 8a, 8b and of the two slide guides 9a, 9b and of the two actuators 10a, 10b is involved therewith.