Valve drive for an internal combustion engine

Abstract

A valve drive for an internal combustion engine may include a camshaft, at least one cam follower, and at least one adjusting device. The camshaft may include at least one cam group including a first cam and a second cam. The at least one adjusting device may include a first adjustable engagement element configured to contact a first guide and a second adjustable engagement element configured to contact a second guide of a slotted guide The at least one adjusting device may further include a stop arrangement axially shiftable relative to a rocker lever shaft. The stop arrangement may include a first stop region and a second stop region. At least one of the first engagement element and the second engagement element may be adjustable via the first stop region and the second stop region, respectively, when the stop arrangement is shifted along the rocker lever shaft.

Claims

1. A valve drive for an internal combustion engine, comprising: a camshaft, at least one cam follower, and at least one adjusting device; the camshaft including at least one cam group non-rotatably fixed on the camshaft, the at least one cam group including a first cam and a second cam disposed axially adjacent to the first cam; the at least one cam follower being drive-connected to the first cam when in a first position and drive-connected to the second cam when in a second position; the at least one adjusting device including a first adjustable engagement element comprising a pin and a second adjustable engagement element comprising a pin, the first engagement element and the second engagement element arranged spaced apart from one another on the at least one cam follower; the first engagement element interacting with a first guide of a slotted guide arranged on the camshaft and the second engagement element interacting with a second guide of the slotted guide arranged on the camshaft; wherein the first engagement element is alternately adjustable between a first basic position and a first switching position, and the second engagement element is alternately adjustable between a second basic position and a second switching position; wherein the first engagement element does not contact the first guide when in the first basic position and the first engagement element interacts with the first guide when in the first switching position; wherein the second engagement element does not contact the second guide when in the second basic position and the second engagement element interacts with the second guide when in the second switching position; and wherein the at least one adjusting device further includes a stop arrangement axially shiftable relative to a rocker lever shaft, the stop arrangement including a first stop region corresponding to the first engagement element and a second stop region corresponding to the second engagement element, the first stop region and the second stop region protruding radially outwardly from the stop arrangement relative to the rocker lever shaft, and wherein at least one of i) the first engagement element is adjustable from the first basic position into the first switching position via the first stop region, and ii) the second engagement element is adjustable from the second basic position into the second switching position via the second stop region, when the stop arrangement is shifted along the rocker lever shaft.

2. The valve drive according to claim 1, wherein the at least one adjusting device further includes a bearing element on which the stop arrangement is shiftably mounted, and wherein the bearing element is structured and arranged to axially guide the stop arrangement along the rocker lever shaft and reduce lateral tilting of the stop arrangement.

3. The valve drive according to claim 2, wherein the at least one adjusting device further includes a linear actuator disposed on the bearing element configured to shift the stop arrangement along the rocker lever shaft.

4. The valve drive according to claim 3, wherein the linear actuator is one of an electromagnetic actuator and a hydraulic actuator.

5. The valve drive according to claim 2, wherein: the at least one adjusting device further includes a counter bearing element nonshiftably arranged relative to the bearing element, the counter bearing element structured and arranged to axially guide the stop arrangement along the rocker lever shaft and reduce lateral tilting of the stop arrangement; and the stop arrangement is shiftably mounted on the bearing element and on the counter bearing element in a direction of the rocker lever shaft extending substantially along the rocker lever shaft.

6. The valve drive according to claim 5, wherein the at least one adjusting device further includes a support arrangement integrally disposed on at least one of the bearing element and the counter bearing element, and wherein the support arrangement comprises a guide profile and at least partly encases the stop arrangement.

7. The valve drive according to claim 2, wherein: the at least one adjusting device further includes a sliding bearing element encasing the rocker lever shaft at least in regions and axially displaceable relative to the rocker lever shaft; and the stop arrangement is displaceably mounted on the bearing element and on the sliding bearing element along the rocker lever shaft.

8. The valve drive according to claim 7, wherein the stop arrangement is integrally disposed on the sliding bearing element.

9. The valve drive according to claim 2, wherein the bearing element is arranged one of i) on the rocker lever shaft, ii) in the rocker lever shaft, and iii) in a cylinder head.

10. The valve drive according to claim 2, wherein the bearing element is a bearing sleeve.

11. The valve drive according to claim 1, wherein at least one of the first stop region and the second stop region include a ramp region.

12. The valve drive according to claim 1, wherein the at least one adjusting device further includes a spring resetting arrangement configured to adjust the stop arrangement into a basic stop position.

13. The valve drive according to claim 12, wherein the spring resetting arrangement is coaxially arranged on the rocker lever shaft.

14. The valve drive according to claim 12, wherein the spring resetting arrangement is one of i) fixed on the bearing element and ii) integrally disposed on the bearing element.

15. The valve drive according to claim 1, wherein the stop arrangement is a stop rod having the first stop region and the second stop region.

16. A valve drive for an internal combustion engine, comprising: a camshaft including at least one cam group non-rotatably fixed on the camshaft, the at least one cam group including a first cam and a second cam disposed axially adjacent to the first cam; at least one cam follower being drive-connected to the first cam when in a first position and drive-connected to the second cam when in a second position; and at least one adjusting device including a first adjustable engagement element comprising a pin and a second adjustable engagement element comprising a pin, the first engagement element and the second engagement element arranged spaced apart from one another on the at least one cam follower, the first engagement element interacting with a first guide of a slotted guide arranged on the camshaft when in a first switching position and not contacting the first guide when in a first basic position, the second engagement element interacting with a second guide of the slotted guide arranged on the camshaft when in a second switching position and not contacting the second guide when in a second basic position, the at least one adjusting device further including a spring resetting arrangement and a stop arrangement axially shiftable relative to a rocker lever shaft, the stop arrangement including a first stop region corresponding to the first engagement element and a second stop region corresponding to the second engagement element, the first stop region and the second stop region protruding radially outwardly from the stop arrangement relative to the rocker lever shaft, the spring resetting arrangement configured to adjust the stop arrangement into a basic stop position; wherein at least one of i) the first engagement element is adjustable from the first basic position into the first switching position via the first stop region, and ii) the second engagement element is adjustable from the second basic position into the second switching position via the second stop region, when the stop arrangement is shifted along the rocker lever shaft; and wherein at least one of the first stop region and the second stop region include a ramp region.

17. The valve drive according to claim 16, wherein the at least one adjusting device further includes a bearing element and the stop arrangement is shiftably mounted on the bearing element, and wherein the bearing element is structured and arranged to axially guide the stop arrangement along the rocker lever shaft and reduce lateral tilting of the stop arrangement.

18. The valve drive according to claim 17, wherein: the at least one adjusting device further includes a counter bearing element nonshiftably arranged relative to the bearing element, the counter bearing element structured and arranged to axially guide the stop arrangement along the rocker lever shaft and reduce lateral tilting of the stop arrangement; and the stop arrangement is shiftably mounted on the bearing element and on the counter bearing element in a direction of the rocker lever shaft extending substantially along the rocker lever shaft.

19. A valve drive for an internal combustion engine, comprising: a camshaft including at least one cam group non-rotatably fixed on the camshaft, the at least one cam group including a first cam and a second cam disposed axially adjacent to the first cam; at least one cam follower drive-connected to the first cam when in a first position and drive-connected to the second cam when in a second position; and at least one adjusting device including: a first adjustable engagement element comprising a pin and a second adjustable engagement element comprising a pin, the first engagement element and the second engagement element arranged spaced apart from one another on the at least one cam follower, the first engagement element interacting with a first guide of a slotted guide arranged on the camshaft when in a first switching position and not contacting the first guide when in a first basic position, the second engagement element interacting with a second guide of the slotted guide arranged on the camshaft when in a second switching position and not contacting the second guide when in a second basic position; a stop arrangement axially shiftable relative to a rocker lever shaft, the stop arrangement including a stop rod having a first stop region corresponding to the first engagement element and a second stop region corresponding to the second engagement element; a bearing sleeve and a counter bearing sleeve nonshiftably arranged relative to the bearing sleeve, the stop arrangement shiftably mounted on the bearing sleeve and the counter bearing sleeve in a direction of the rocker lever shaft extending substantially along the rocker lever shaft; a linear actuator disposed on the bearing sleeve configured to shift the stop arrangement along the rocker lever shaft; and wherein at least one of i) the first engagement element is adjustable from the first basic position into the first switching position via the first stop region, and ii) the second engagement element is adjustable from the second basic position into the second switching position via the second stop region, when the stop arrangement is shifted along the rocker lever shaft.

20. The valve drive according to claim 19, wherein the linear actuator is one of an electromagnetic actuator and a hydraulic actuator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) It shows, in each case schematically

(2) FIG. 1 a view of a valve drive according to the invention;

(3) FIG. 2 a view of an adjusting device with a stop arrangement in a first switch-over position;

(4) FIG. 3 a view of an adjusting device with a stop arrangement in a second switch-over position;

(5) FIG. 4 a view of an adjusting device with a stop arrangement, with a bearing element and with a counter bearing element;

(6) FIG. 5 a view of an adjusting device with a stop arrangement integrally formed on a sliding bearing element;

(7) FIG. 6 a view of an adjusting device with a support arrangement moulded on the bearing element.

DETAILED DESCRIPTION

(8) According to FIG. 1, a valve drive 1 according to the invention comprises a camshaft 2 and a cam follower 3, wherein the camshaft 2 comprises a first cam group 4 and a second cam group 5 which are non-rotatably fixed on the camshaft 2. The first cam group 4 comprises a first cam 4a and a second cam 4b axially adjacent to the first cam 4a. The second cam group 5 comprises a first cam 5a and a second cam 5b which is fixed on the camshaft 2 adjacent to the first cam 5a. The cam follower 3 is drive connected in a first position with the first cams 4a and 5a of the cam groups 4 and 5 and in a second position with the second cams 4b and 5b of the cam groups 4 and 5. For this purpose, the cam follower 3 comprises a first roller 3a and a second roller 3b which each lie against the first cam 4a and 5a or against the second cam 4b and 5b and interact with these.

(9) For adjusting the cam follower 3 into the first position or into the second position, the valve drive 1 comprises an adjusting device 6 which comprises a first adjustable engagement element 7a and a second adjustable engagement element 7b. Here, the first engagement element 7a interacts with a first guide 8a of a slotted guide and the second engagement element 7b interacts with a second guide 8b of a slotted guide 8 arranged on the camshaft 2. The first engagement element 7a and the second engagement element 7b are alternately adjustable between a basic position and a switching position, wherein in the basic position there is no contact with the associated guide 8a or 8b and in the switching position the respective engagement element 7a or 7b interacts with the associated guide 8a or 8b. The cam follower 3 is shiftably arranged in a rocker lever 9, wherein the rocker lever 9 is rotatably fixed on a rocker lever shaft 10.

(10) In order to adjust the engagement elements 7a and 7b, the adjusting device 6 according to the invention comprises a stop arrangement 11 that is axially shiftable relative to the rocker lever shaft 10 with a first stop region 12a for the first engagement element 7a and with a second stop region 12b for the second engagement element 7b. In this exemplary embodiment, the stop arrangement 11 is a U-shaped stop rod. When shifting the stop arrangement 11 along the rocker lever shaft 10, the respective engagement element 7a or 7b is then adjustable by the respective stop region 12a or 12b from the basic position into the switching position through an upwards movement of the rocker lever 9.

(11) In addition, the adjusting device 6 comprises a bearing element 13 fixed on the rocker lever shaft 10, on which the stop arrangement 11 is shiftably mounted. The bearing element 13 in this exemplary embodiment is a bearing sleeve, in which the stop arrangement 11 is shiftably mounted by a linear actuator 14 along the rocker lever shaft 10. The linear actuator 14 can for example be an electromagnetic actuator or a hydraulic actuator. By way of the bearing element 13 and the stop arrangement 11 mounted in the bearing element 13 an undesirable lateral tilting of the stop arrangement 11 for example because of its own weight can be additionally reduced.

(12) FIG. 2 shows a view of the adjusting device 6 with the stop arrangement 11 and with the bearing element 13 in the first switch-over position. When activating the valve drive 1, the first engagement element 7a is actuated by the first stop region 12a and the second engagement element 7b by the second stop region 12b of the stop arrangement 11. The stop arrangement 11 is designed so that an actuation of the respective engagement element 7a or 7b is supported by an upwards movement of the rocker lever 9. In the first switch-over position, the first stop region 12a of the stop arrangement 11 is arranged above the first engagement element 7a. By way of an upwards movement of the rocker lever 9, the first engagement element 7a also moves upwards so that by way of the first stop region 12a the first engagement element 7a is now adjusted from the basic position into the switching position. The first engagement element 7a now interacts with the first guide 8a and the cam follower 3 is moved from the first position into the second position. In the process, the rocker lever 9 is switched over for example from a braking operation to a normal operation.

(13) FIG. 3 shows a view of the adjusting device 6 with the stop arrangement 11 and with the bearing element 13 in the second switch-over position. The second stop region 12b is arranged above the second engagement element 7b. By way of an upwards movement of the rocker lever 9, the second engagement element 7b is actuated by the second stop region 12b and interacts with the second guide 8b. Accordingly, the cam follower 3 is adjusted from the second position into the first position and the rocker lever 9 is switched over in the process for example from a normal operation to a braking operation.

(14) FIG. 4 shows a view of the adjusting device 6 with a counter bearing element 15 in the form of a counter bearing sleeve. The counter bearing element 15 is arranged not shiftable relative to the bearing element 13 and the stop arrangement 11 is shiftably mounted on the bearing element 13 and on the counter bearing element 15 along the rocker lever shaft 10. The counter bearing element 15 supports the shifting of the stop arrangement 11 additionally so that an undesirable lateral tilting of the stop arrangement 11 for example because of its own weight is prevented.

(15) FIG. 5 shows a view of the adjusting device 6, wherein the stop arrangement 11 is integrally formed on a sliding bearing element 16. The sliding bearing element 16 axially encases the rocker lever shaft 10 and is shiftably mounted on the rocker lever shaft 10. The stop arrangement 11 is integrally formed on the sliding bearing element 16 and, together with the sliding bearing element 16, is guided by a guide rod 17 shiftably mounted on the bearing element 13. Because of this, undesirable lateral tilting of the stop arrangement 11 can be avoided. In this exemplary embodiment, the first stop region 12a and the second stop region 12b each comprise a ramp region. The ramp region can also be configured in the form of a double ramp in order to make possible a continuous adjustment of the respective engagement element 7a and 7b and thus of the rocker lever 9.

(16) The adjusting device 6 also comprises a resetting arrangement 18 which in this exemplary embodiment is a spring resetting arrangement 19. The spring resetting arrangement 19 sets the stop arrangement 11 into a basic stop position, which can be the first switch-over position or the second switch-over position or even a neutral position. By way of the spring resetting arrangement 19, the stop arrangement 11 is in the provided basic stop position even between the switch-over operations. Additionally, the spring resetting arrangement 19 makes possible a resetting of the stop arrangement 11 even in a currentless state. In this exemplary embodiment, the spring resetting arrangement 19 comprises a coil spring 20 which is arranged coaxially about the rocker lever shaft 10 between the rocker lever 9 and the sliding bearing element 16 and fixed on these.

(17) In FIG. 6, a schematic view of the adjusting device 6 is shown, wherein the adjusting device 6 comprises a support arrangement 21, which is integrally formed on the bearing element 13. The support arrangement 21 in this exemplary embodiment is configured in the form of a guide profile which partly encases the stop arrangement 11. Thus, the stop arrangement 11 is guided in the support arrangement 21 along the rocker lever shaft 10. Advantageously, a lateral tilting of the stop arrangement 11 and in particular a deformation of the stop arrangement 11 during the adjusting of the engagement elements 7a or 7b can be advantageously prevented.

(18) On the whole, the first engagement element 7a and the second engagement element 7b in the valve drive 1 according to the invention can be jointly activated by the stop arrangement 11, as a result of which on the whole the activation of the valve drive 1 is simplified. In addition, the number of the linear actuators and because of this the total costs of the valve drive 1 and the maintenance costs can be reduced.