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, at least one adjusting device, and at least one control shaft. The camshaft may include at least one cam group. The at least one cam group may include a first cam and a second cam. The at least one cam follower may be drive-connected to the first cam in a first position and to the second cam in a second position. The at least one adjusting device may include a first adjustable engagement element and a second adjustable engagement element. alternately adjustable between a basic position and a switching position. The at least one control shaft may include at least one control element group including a first control element and a second control element adjustable to a switching element position and to a basic element position.

Claims

1. A valve drive for an internal combustion engine, the valve drive comprising: a camshaft and at least one cam follower; 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 of the at least one cam group in a first position and to the second cam of the at least one cam group in a second position; at least one adjusting device including a first adjustable engagement element and a second adjustable engagement element; the first engagement element comprising a pin interacting with a first slotted guide arranged on the camshaft and the second engagement element comprising a pin interacting with a second slotted guide arranged on the camshaft; wherein the first engagement element and the second engagement element are alternately adjustable between a basic position and a switching position; wherein, when in the basic position, the first engagement element and the second engagement element do not contact the first slotted guide and the second slotted guide, respectively, and, when in the switching position, the first engagement element and the second engagement element interact with the first slotted guide and the second slotted guide, respectively; at least one control shaft including at least one control element group, the at least one control element group including a first control element arranged on the at least one control shaft and a second control element arranged on the at least one control shaft, the first control element and the second control element each having a radially outwardly projecting stop region, wherein the first control element and the second control element are adjustable, relative to the at least one control shaft, to a switching element position and to a basic element position; and wherein in the switching element position the first engagement element and the second engagement element are adjusted from the basic position to the switching position via the stop region of a respective one of the first control element and the second control element, and wherein in the basic element position the respective one of the first control element and the second control element does not contact the first engagement element and the second engagement element, respectively.

2. The valve drive according to claim 1, wherein at least one of the first control element and the second control element is a control cam.

3. The valve drive according to claim 2, wherein: the at least one control shaft further includes an inner shaft and an outer shaft radially encasing the inner shaft in at least some regions, the inner shaft fixed within and radially spaced apart from the outer shaft via a radially projecting stop element that defines a lever space between the outer shaft and the inner shaft; and the control cam includes a lever element arranged in the lever space partly rotatably between and lying against the outer shaft and the inner shaft, the lever element encasing the inner shaft in at least some regions, and wherein a first lateral face of the lever element lies against the stop element in the switching element position and a second lateral face of the switching element lies against the stop element in the basic element position.

4. The valve drive according to claim 3, wherein: the lever element and the stop element delimit a first pressure space between the first lateral face and the stop element in the basic element position and a second pressure space between the second lateral face and the stop element in the switching element position, and wherein the lever space has the first pressure space and the second pressure space; and the control cam further includes a control valve arrangement structured and arranged to change a pressure in at least one of the first pressure space and the second pressure space such that the lever element adjusts between the switching element position and the basic element position.

5. The valve drive according to claim 4, wherein the control valve arrangement is hydraulic and includes a directional control valve that is adjustable into a blocking rest position.

6. The valve drive according to claim 1, wherein at least one of the first control element and the second control element is an adjusting rod.

7. The valve drive according to claim 6, wherein: the at least one control shaft further includes a radial adjusting bore having a first stop face and a second stop face; the adjusting rod is arranged within regions of the adjusting bore and fixed in the adjusting bore such that the adjusting rod axially shifts via a radial boundary edge of the adjusting rod; and the adjusting rod including the stop region radially projecting from the adjusting bore on one side such that the adjusting rod adjusts between the switching element position and the basic element position via an axial shift of the adjusting rod in the adjusting bore.

8. The valve drive according to claim 7, wherein: in the basic element position, the boundary edge of the adjusting rod and the first stop face define a first pressure space and, in the switching element position, the boundary edge of the adjusting rod and the second stop face define a second pressure space; and the adjusting rod further includes a control valve arrangement structured and arranged to change a pressure in at least one of the first pressure space and the second pressure space such that the adjusting rod adjusts between the switching element position and the basic element position.

9. The valve drive according to claim 8, wherein the control valve arrangement is hydraulic and includes a directional control valve that is adjustable into a blocking rest position.

10. The valve drive according to claim 1, wherein at least one of the first control element and the second control element is a rotary lever.

11. The valve drive according to claim 10, wherein: the at least one control shaft further includes a longitudinal groove radially circulating about the at least one control shaft in at least some regions; and the rotary lever includes a circumferential region encasing the at least one control shaft on the longitudinal groove, and wherein the rotary lever further includes a connecting pin projecting through a through-bore in the circumferential region and into the longitudinal groove of the at least one control shaft, the connecting pin tiltably connecting the rotary lever with the at least one control shaft such that the rotary lever adjusts between the switching element position and the basic element position via an adjustment of the connecting pin in the longitudinal groove.

12. The valve drive according to claim 11, wherein: in the basic element position, the connecting pin and a first lateral face of the longitudinal groove define a first pressure space and, in the switching element position, the connecting pin and a second lateral face of the longitudinal groove define a second pressure space; and the rotary lever further includes a control valve arrangement structured and arranged to change a pressure in at least one of the first pressure space and the second pressure space such that the rotary lever adjusts between the switching element position and the basic element position.

13. The valve drive according to claim 1, wherein the at least one control shaft for at least one of the first control element and the second control element includes a spring resetting arrangement.

14. The valve drive according to claim 13, wherein the spring resetting arrangement includes at least one of a torsion spring, a coil spring, and a bending spring.

15. The valve drive according to claim 1, wherein the at least one control shaft is a rocker lever shaft.

16. The valve drive according to claim 1, wherein the first engagement element and the second engagement element are structured and arranged to extend radially relative to the camshaft.

17. The valve drive according to claim 1, wherein: the at least one control shaft is a rocker lever shaft including an inner shaft and an outer shaft at least partially encasing the inner shaft, the inner shaft arranged within and radially spaced apart from the outer shaft via a stop element projecting radially therefrom, the inner shaft and the outer shaft defining a lever space therebetween; and at least one of the first control element and the second control element is a control cam, the control cam including a lever element at least partially arranged within the lever space, the lever element at least partially encasing the inner shaft and rotatable about the inner shaft such that a first lateral face of the lever element abuts the stop element when the lever element is in the switching element position and a second lateral face of the lever element abuts the stop element when the lever element is in the basic element position.

18. The valve drive according to claim 1, wherein: the at least one control shaft further includes a radial adjusting bore having a first stop face and a second stop face; and at least one of the first control element and the second control element is an adjusting rod having a radial boundary edge, the adjusting rod arranged at least partially within the adjusting bore such that the adjusting rod axially shifts via the boundary edge, the adjusting rod including the stop region projecting on one side such that the adjusting rod is adjustable between the switching element position and the basic element position via an axial shift of the adjusting rod within the adjusting bore.

19. The valve drive according to claim 1, wherein: the at least one control shaft further includes a longitudinal groove radially circulating about the at least one control shaft in at least one region; and at least one of the first control element and the second control element is a rotary lever having a circumferential region encasing the at least one control shaft on the longitudinal groove, the rotary lever including a connecting pin projecting through a through-bore disposed in the circumferential region and into the longitudinal groove, the connecting pin tiltably connecting the rotary lever and the at least one control shaft such that the rotary lever adjusts between the switching element position and the basic element position via an adjustment of the connecting pin in the longitudinal groove.

20. An internal combustion engine comprising the valve drive of claim 1.

Description

DETAILED DESCRIPTION OF THE DRAWINGS

(1) It shows, in each case schematically

(2) FIG. 1 a part view of a valve drive with a control shaft;

(3) FIG. 2 a view of a control element group with a first control element and with a second control element in the form of a control cam;

(4) FIG. 3 a view of the control element group shown in FIG. 2 with a spring resetting arrangement with a torsion spring;

(5) FIG. 4 a sectional view of a control element in the form of a control cam;

(6) FIG. 5 a sectional view of the control element shown in FIG. 3 in the form of a control cam with a spring resetting arrangement located inside;

(7) FIG. 6 a sectional view of the control element shown in FIG. 3 in the form of a control element with a spring resetting arrangement located outside;

(8) FIG. 7 a sectional view of the control element shown in FIG. 3 in the form of a control cam with a spring resetting arrangement on a directional control valve;

(9) FIG. 8 a sectional view of a control element in the form or an adjusting rod;

(10) FIG. 9 a sectional view of a control element in the form of a rotary lever;

(11) FIG. 10 a part sectional view of the control element shown in FIG. 9 in the form of a rotary lever.

DETAILED DESCRIPTION

(12) FIG. 1 shows a part view of a valve drive 1 of an internal combustion engine which is not shown in more detail. The valve drive 1 comprises a camshaft 2 and a cam follower 3. The camshaft 2 comprises a first cam group 4 with a first cam 4a and with a second cam 4b as well as a second cam group 5 with a first cam 5a and with a second cam 5b. The first cam group 4 and the second cam group 5 are non-rotatably fixed on the camshaft 2. By way of the first cam group 4 and the second cam group 5, a corresponding cylinder which is not shown in more detail can be activated in that for example the first cam group 4 activates an inlet valve of the cylinder and the second cam group 5 an exhaust valve of the cylinder.

(13) The cam follower 3 is drive-connected via a first roller 3a with the first cam group 4 and via a second roller 3b with the second cam group 5. In a first position, the rollers 3a and 3b interact with the first cams 4a and 5a of the respective cam groups 4 and 5 and in a second position the rollers 3a and 3b act with the second cams 4b and 5b of the respective cam groups 4 and 5.

(14) 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 6a and a second adjustable engagement element 6b. The first engagement element 6a interacts with a first slotted guide 7a arranged on the camshaft 2 and the second engagement element 6b interacts with a second slotted guide 7b arranged on the camshaft 2. The first engagement element 6a and the second engagement element 6b are alternately adjustable between a basic position and a switching position, wherein in the basic position there is no contact with the associated slotted guide 7a or 7b and in the switching position the respective engagement element 6a or 6b interacts with the associated slotted guide 7a or 7b.

(15) The valve drive 1 also comprises a non-rotatable control shaft 9 which is rotation-symmetrical about a longitudinal axis 8 with a control element group 10, wherein the control element group 10 comprises a first control element 10a that is rotatable on the control shaft 9 and a second control element 10b that is rotatable on the control shaft 9. In this exemplary embodiment, the control shaft 9 and a rocker lever shaft of the valve drive 1 are combined. According to the invention, the first control element 10a comprises a stop region 11 for the first engagement element 6a and the second control element 10b likewise comprises the stop region 11 for the second engagement element 6b. Upon the rotation of the first control element 10a on the control shaft 9, the first engagement element 6a can be adjusted by the stop region 11 from the basic position into the switching position. Upon the rotation of the second control element 10b of the control shaft 9, the second engagement element 6b can be adjusted by the stop region 11 from the basic position into the switching position.

(16) According to the invention the respective first control elements 10a and the respective second control elements 10b of the control shaft 9 can be actuated independently of one another. With multiple control elements 10a, 10b on a control shaft 9, the respective engagement elements 6a and 6b can thus be adjusted in any order and the corresponding cylinders can consequently be activated and deactivated in any order. Advantageously, the activation order can also differ from the deactivation order and the activation orders and the deactivation orders be different in individual operating cycles.

(17) FIG. 2 shows a view of the control element group 10 with a first control element 10a and with a second control element 10b, both in the form of a control cam 12. The control cams 12a and 12b can be rotated independently of one another relative to the non-rotatable control shaft 9 and with the stop regions 11, adjust the engagement elements 6a and 6b. Accordingly, the first control cam 12a is rotated relative to the control shaft 9 in FIG. 2 and is in the switching element position in contact with the first engagement element 6a. The second control cam 12b is in the basic element position and has no contact with the second engagement element 6b.

(18) In FIG. 3, a view of the control element group 10 shown in FIG. 2 is shown with a resetting arrangement 13 in the form of a spring resetting arrangement 14.

(19) The spring resetting arrangement 14 comprises torsion spring 15a and 15b, which make possible resetting the first control cam 12a and the second control cam 12b into the basic element position. The torsion springs 15a and 15b are fixed to the non-rotatable control shaft 9 and to the first control cam 12a and to the second control cam 12b so that upon a rotation of the control cams 12a and 12b a resetting force through the spring force of the torsion spring 15a and 15b acts on the control cams 12a and 12b bringing these into the basic element position.

(20) FIG. 4 shows a sectional view of the control elements 10a or 10b in the form of the control cam 12. The control shaft 9 comprises an inner shaft 16 and an outer shaft 17 encasing the inner shaft 16 in regions, wherein the inner shaft 16 is fixed in the non-rotatable outer shaft 17 through a radially projecting stop element 18. Between the outer element 17 and the inner shaft 16 a lever space 19 is formed in which the control cam 12 with a lever element 20 is arranged. The lever element 20 is rotatably arranged in the lever space 19. In the switching element position, the lever element 20 lies against the stop element 18 of the inner shaft 16 with a first lateral face 20a and in the basic element position the lever element 20 lies against the stop element 18 of the inner shaft 16 with a second lateral face 20b. The stop region 11 of the control cam 12 is fixed to the lever element 20 and radially projects through a tilting aperture 21 of the outer shaft 17.

(21) The lever element 20 and the stop element 18 of the inner shaft 16 form a first pressure space 22a between the first lateral face 20a and the stop element 18 and a second pressure space 22b between the second lateral face 20b and the stop element 18. Here, the first pressure space 22a and the second pressure space 22b are a part of the lever space 19 and are arranged on both sides of the stop element 18 of the inner shaft 16. By way of a control arrangement 23, the pressure in the first pressure space 22a and/or in the second pressure space 22b can be changedfor example hydraulicallyso that the lever element 20 of the inner shaft 16 is rotated. Consequently, the stop region 11 also rotates relative to the non-rotatable control shaft 9 and adjusts the corresponding engagement element 6a or 6b.

(22) In FIG. 5, in FIG. 6 and in FIG. 7, sectional views of the control cam 12 shown in FIG. 3 with the spring resetting arrangement 14 are shown, which comprises a coil spring 24. In FIG. 5, the coil spring 24 is arranged located inside between the stop element 18 and the first lateral face 20a of the lever element 20; in FIG. 6, the coil spring 24 is arranged located outside on the stop region 11 of the control cam 12 and in FIG. 7 the coil spring is arranged on a directional control valve of the hydraulic control arrangement 23. By way of the spring resetting arrangement 14, the control cam 12 can be brought back from the switching element position into the basic element position in a simple energy-saving manner.

(23) FIG. 8 shows a sectional view of the control element 10a or 10b in the form of an adjusting rod 25. The control shaft 9 in this case comprises a radial adjusting bore 26 with a first stop face 26a and with a second stop face 26b. In the adjusting bore 26 the adjusting rod 25 is arranged in regions and axially shiftable by a radial boundary edge 27. The stop region 11 of the adjusting rod 25 projects from the adjusting bore 26 on one side, so that through an axial shifting of the adjusting rod 25 in the adjusting bore 26 the adjusting rod 25 can change between the switching element position and the basic element position.

(24) The boundary edge 27 of the adjusting rod 25 and the first stop face 26a form the first pressure space 22a and the boundary edge 27 of the adjusting rod 25 and the second stop face 26b form the second pressure space 22b. The control arrangement 23 can changefor example hydraulicallythe pressure in the first pressure space 22a and/or in the second pressure space 22b so that the adjusting rod 25 can change between the switching element position and the basic element position.

(25) FIG. 9 shows a sectional view of the control element 10a or 10b in the form of a rotary lever 28 and FIG. 10 shows a part sectional view of the rotary lever 28 shown in FIG. 9. The control shaft 9 in this case comprises a longitudinal groove 29 radially circulating about the control shaft 9 in regions and the rotary lever 28 a circumferential region 30 encasing the control shaft 9 on the longitudinal groove. A connecting pin 31 projects through a radial through-bore 32 in the circumferential region 30 into the longitudinal groove 29 of the control shaft 9 and rotatably connects the rotary lever 28 with the control shaft 9. By way of a movement of the connecting pin 31 along the longitudinal groove 29, the rotary lever 28 can be rotated on the control shaft 9 and change between the switching element position and the basic element position.

(26) The connecting pin 31 of the rotary lever 28 forms the first pressure space 22a with a first lateral face 29a of the longitudinal groove 29 and the second pressure space 22b with a second lateral face 29b of the longitudinal groove 29. Through a control arrangement 23, the pressure in the first pressure space 22a of the rotary lever 28 and/or in the second pressure space 22b of the rotary lever 28 can be changedfor example hydraulicallyso that the rotary lever 28 can change between the switching element position and the basic element position.