Valve drive for an internal combustion engine

Abstract

A valve drive for an internal combustion engine may include a cam shaft including at least two cams rotationally attached thereto. The valve drive may also include a cam follower including a roller bolt including a rotatable roller arranged thereon. Additionally, the valve drive may include a lever device drivingly connected to the cam follower configured to adjust the cam follower between a first position and a second position. The valve drive may further include a rotatably supported control lever drivingly connected to the cam follower configured to adjust at least one valve of an internal combustion engine. The valve drive may include an actuator drivingly connected to the lever device configured to adjust the cam follower between the first position and the second position, the actuator may be connected to the cam follower in an articulated manner via the lever device.

Claims

1. A valve drive for an internal combustion engine, comprising: a cam shaft including at least two cams rotationally attached thereto; a cam follower including a roller bolt and a rotatable roller arranged on the roller bolt; a lever device drivingly connected to the cam follower configured to adjust the cam follower between a first position, in which the cam follower is drivingly connected to a first cam of the at least two cams, and a second position, in which the cam follower is drivingly connected to a second cam of the at least two cams; a rotatably supported control lever drivingly connected to the cam follower via an accommodation of the rotatably supported control lever; and a linear actuator drivingly connected to the lever device configured to adjust the cam follower between the first position and the second position; wherein the linear actuator is connected to the cam follower in an articulated manner via the lever device.

2. The valve drive according to claim 1, wherein the linear actuator and the rotatably supported control lever are supported on an axis.

3. The valve drive according to claim 1, wherein the rotatably supported control lever includes a further accommodation, in which an axis is at least partially accommodated.

4. The valve drive according to claim 3, wherein the further accommodation is an aperture which the axis engages.

5. The valve drive according to claim 1, wherein the lever device is a two-legged toggle lever including a first leg and a second leg, wherein the first leg and the second leg are rigidly connected to one another via a toggle of the two-legged toggle lever and are pivotable about an axis of rotation extending through the two-legged toggle lever.

6. The valve drive according to claim 5, wherein at least one of i) the first leg is connected to the linear actuator in an articulated manner via a first joint and ii) the second leg is connected to the cam follower in an articulated manner via a second joint.

7. The valve drive according to claim 6, wherein: the linear actuator is supported on an axis; the linear actuator includes a sleeve arranged on the axis such that the sleeve is adjustable in an axial direction; and the first joint is attached to the sleeve.

8. The valve drive according to claim 7, wherein an axis of rotation of the rotatably supported control lever extends along the axial direction.

9. The valve drive according to claim 7, wherein the sleeve is axially adjustable on the axis between a first sleeve position, in which the lever device is in a first lever position, and a second sleeve position, in which the lever device is in a second lever position.

10. The valve drive according to claim 9, wherein the linear actuator includes an actuator housing and an actuator element protruding from the actuator housing, the actuator element adjustable between a retracted position and an extended position, and wherein the actuator element and the sleeve are configured such that when the sleeve is in the first sleeve position the actuator element is in one of the retracted position and the extended position and when the sleeve is in the second sleeve position the actuator element is in the other of the retracted position and the extended position.

11. The valve drive according to claim 6, wherein the first joint is structured as an elongated hole disposed on the first leg, and wherein a protrusion protruding from the sleeve is adjustably arranged within the elongated hole.

12. The valve drive according to claim 6, wherein the second joint is structured as an elongated hole disposed on the second leg, and wherein a protrusion protruding from the cam follower is adjustably arranged within the elongated hole.

13. The valve drive according to claim 1, wherein the accommodation of the rotatably supported control lever has an aperture through which the roller bolt engages.

14. The valve drive according to claim 13, wherein the accommodation of the rotatably supported control lever includes two fork arms defining the aperture through which the roller bolt engages, and wherein the two fork arms of the rotatably supported control lever define a space therebetween in which the roller is arranged.

15. The valve drive according to claim 5, wherein the first leg and the second leg are arranged at an obtuse angle to one another in a cross section extending perpendicular to the axis of rotation.

16. The valve drive according to claim 1, wherein the lever device is adjustable between a first lever position, in which the cam follower is in the first position, and a second lever position, in which the cam follower is in the second position.

17. The valve drive according to claim 1, wherein an axis of rotation of the lever device extends perpendicular to an axis of rotation of the rotatably supported control lever.

18. The valve drive according to claim 1, wherein the roller is arranged on the roller bolt such that the roller is rotationally adjustable relative thereto, and the roller and the roller bolt are adjustable jointly along an axial direction of the roller bolt between the first position of the cam follower, in which the roller is drivingly connected to the first cam, and the second position of the cam follower, in which the roller is drivingly connected to the second cam.

19. The valve drive according to claim 1, wherein the rotatably supported control lever has two accommodations that drivingly connect the rotatably supported control lever to the cam follower, the two accommodations structured and arranged to receive the roller bolt.

20. An internal combustion engine comprising a valve drive including: a cam shaft including at least two cams rotationally attached thereto; a cam follower including a roller bolt and a rotatable roller arranged on the roller bolt; a lever device drivingly connected to the cam follower configured to adjust the cam follower between a first position, in which the cam follower is drivingly connected to a first cam of the at least two cams, and a second position, in which the cam follower is drivingly connected to a second cam of the at least two cams; a rotatably supported control lever drivingly connected to the cam follower configured to adjust at least one valve of an internal combustion engine via an accommodation of the rotatably supported control lever; and a linear actuator drivingly connected to the lever device configured to adjust the cam follower between the first position and the second position; an axis structured as a bolt, the linear actuator and the rotatably supported control lever arranged on the axis; wherein the linear actuator is connected to the cam follower in an articulated manner via the lever device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In each case schematically:

(2) FIG. 1 shows an example of a valve drive according to the invention, in which the cam follower is in a first position, in which it is drivingly connected to a first cam, which is arranged on the cam shaft,

(3) FIG. 2 shows the valve drive of FIG. 1 comprising the cam follower in a second position, in which it is drivingly connected to a second cam, which is arranged on the cam shaft.

DETAILED DESCRIPTION

(4) FIGS. 1 and 2 illustrate an example of a valve drive 1 according to the invention. The valve drive 1 comprises a cam shaft 2, on which two cams 3a, 3b of a different cam contour or of a different cam stroke, respectively, are attached in a rotationally fixed manner. The valve drive further has a cam follower 4, which comprises a roller bolt 5. A roller 6 is arranged on the roller bolt 5. The roller 6 is embodied so as to be capable of being rotated relative to the roller bolt 5. The roller 6 and the roller bolt 5 can be adjusted jointly along an axial direction A of the roller bolt 5which can be determined by the course of a longitudinal center axis M of the cylindrical roller bolt 5, namely between a first position of the cam follower 4, in which the roller 6 is drivingly connected to the first cam 3a, and a second position of the cam follower 4, in which the roller 6 is drivingly connected to the second cam 3b. FIG. 1 shows the cam follower 4 in the first position, FIG. 2 in the second position. In addition, the valve drive 1 comprises a rotatably supported control lever 13, which is drivingly connected to the cam follower 4 for controlling the valve (not shown) of the internal combustion engine.

(5) According to FIGS. 1 and 2, the valve drive 1 further comprises a lever device 7, which is drivingly connected to the cam follower 4, for adjusting the cam follower 4 between the first and the second position. For this purpose, the valve drive 1 comprises an actuator 8, which is mechanically coupled or drivingly connected, respectively, to the lever device 7. The actuator 8 is connected to the control lever 13 or is fastened thereto, respectively, by means of an axis 14. The actuator 8 can be embodied as electrically driven actuator. In a variation, the actuator 8, however, can also be embodied as hydraulic actuator, which is supported on the axis 14 as well as on a bearing part (not shown), on which the control lever 13 is rotatably supported. Such a hydraulic actuator, however, can also be fastened directly to the axis 14.

(6) To fasten the axis 14 to the control lever 13, the latter has a first accommodation 15a, in which the axis 14 is partially accommodated. In the example of the figures, the first accommodation 15a is embodied as first aperture 16a, so that the axis 14 engages through the aperture 16a. The control lever 13 furthermore has two second accommodations 15b, in which the roller bolt 5 is accommodated. The second accommodations 15b are in each case embodied as second aperture 16b, through which the roller bolt 5 engages. The direct fastening of roller bolt 5 and axis 14 on the same component, namely the control lever 13, has the result that the number of required components can be kept small.

(7) As can furthermore be seen in FIGS. 1 and 2, the actuator 8 is connected to the cam follower 4 in an articulated manner by means of the lever device 7. The lever device 7 is thereby embodied as two-legged toggle lever 9 comprising a first leg 10a and comprising a second leg 10b. The first leg 10a is connected to the actuator 8 in an articulated manner by means of a first joint 11a. The second leg 10b is connected to the cam follower 4 in an articulated manner by means of a second joint 11b. The toggle lever 9 of the lever device 7 can be adjusted between a first lever position, in which the roller 6 of the cam follower 4 is in the first position, and a second lever position, in which the roller 6 of the cam follower 4 is in the second position.

(8) The actuator 8 also comprises a sleeve 17, which is arranged on the axis 14 so as to be capable of being adjusted along the axial direction A. The first joint 11a of the lever device 7 is arranged on the sleeve 17. On the axis 14, which can be embodied as bolt, the sleeve 17 can be axially adjusted between a first sleeve position, in which the toggle lever 9 of the lever device 7 is in the first lever position, and a second sleeve position, in which the toggle lever 9 of the lever device 7 is in the second lever position. The two legs 10a, 10b are rigidly connected to one another via a toggle 12 of the toggle lever 9 and can be rotated about an axis of rotation D, which runs through the toggle 12. In the example scenario, the two legs 10a, 10b are arranged at an obtuse angle to one another in a cross section perpendicular to the axis of rotation D. An axis of rotation of the control lever 13, which is not illustrated in detail in the figures, extends along the axial direction A, thus in the drawing plane of the figures. As suggested in the figures, the axis of rotation D of the lever device 7 extends perpendicular to the axis of rotation of the control lever 13, thus perpendicular to the drawing plane of the figures.

(9) To embody the first joint 11a, provision is made on the first leg 10a of the toggle lever 9 for a first elongated hole 18a. A first protrusion 19a, which protrudes from the sleeve 17, is adjustably guided in the first elongated hole 18a. To embody the second joint 11b, a second elongated hole 18b is embodied on the second leg 10b of the toggle lever 9. A second protrusion 19b, which protrudes from the roller bolt 5 of the cam follower 4, is adjustably guided in the second elongated hole 18b. In a variation of the example, the two legs 10a, 10b can also be realized as extendable telescopic arms of a variable length (not shown).

(10) In this case, the provision of elongated holes 18a, 18b can be forgone. To fasten the roller bolt 5 to the control lever 13, provision is made for a second aperture 16b on two fork arms 21a, 21b, which are molded on the control lever 13. For this purpose, a passage opening can in each case be embodied in each fork arm 21a, 21b, wherein the two passage openings are arranged in alignment with one another along the axial direction A. A space 22, in which the roller 6, which is provided on the roller bolt 5, is arranged, is embodied between the two fork arms 21a, 21b.

(11) According to FIG. 1, the actuator 8 comprises an actuator housing 23 as well as an actuator element 20, which protrudes from the actuator housing 23 and which can be linearly adjusted between a retracted and an extended position. The actuator element 20 and the sleeve 17 are matched to one another in such a way that the sleeve 17 is in the first sleeve position when the actuator element 20 is retracted and is in the second sleeve position when the actuator element 20 is extended, or vice versa.

(12) If the actuator element 20 is adjusted from the retracted position shown in FIG. 1 into the extended position, an axial adjustment of the sleeve 17 on the axis along the axial direction A is associated therewith. The sleeve 17 is thereby adjusted from the first sleeve position into the second sleeve position. A rotational movement of the toggle lever 9 of the lever device 7 about the axis of rotation D is associated with the axial movement of the sleeve 17. This leads to a linear movement of the roller bolt 5, including the roller 6 relative to the cam shaft 2, so that the roller 6 of the cam follower 4 is adjusted from the first into the second position. Analogously, an adjustment of the actuator element 20 from the extended into the retracted position effects an adjustment of the roller 6 of the cam follower 4 from the second into the first position. The adjustment movements of actuator element 20, sleeve 17, toggle lever 9, roller bolt 5 and roller 6 is illustrated schematically in FIG. 1 by arrows 24.

(13) The actuator element 20 can also be embodied as annular component and can be positioned or supported, respectively, directly on the axis 14. Due to the axially parallel position to the sleeve 17, this embodiment leads to a reduction of the transverse forces onto said sleeve; a guide, which has a reduced bearing clearance thereof, is thus possible.