Valve Drive Device, in Particular for an Internal Combustion Engine of a Motor Vehicle, and Method for Operating Such a Valve Drive Device

Abstract

A valve drive device has a camshaft which includes a shaft element and a cam piece which can be driven by the shaft element and a first cam effecting a first stroke of a valve and a second cam effecting a second stroke of the valve, and is displaceable in the axial direction of the camshaft relative to the shaft element between a first position, in which the valve can be actuated by the first cam, and a second position in which the valve can be actuated by the second cam, and has an electrically controllable actuator via which the cam piece is displaceable relative to the shaft element in the axial direction as a result of an electrical control of the actuator. The actuator pushes the cam piece alternately back and forth between the positions in the case of successive electrical controls occurring with the same polarity.

Claims

1.-10. (canceled)

11. A valve drive device (10), comprising: a camshaft (12) which comprises a shaft element (18) and a cam piece (20) which is drivable by the shaft element (18) and which has a first cam (24) effecting a first stroke of a valve and a second cam (26) effecting a second stroke of the valve different from the first stroke and which is displaceable in an axial direction (22) of the camshaft (12) relative to the shaft element (18) between a first position, in which the valve is actuatable by the first cam (24), and a second position in which the valve is actuatable by the second cam (26); an electrically controllable actuator (28) via which, as a result of an electrical control of the actuator (28), the cam piece (20) is displaceable relative to the shaft element in the axial direction (22) of the camshaft (12); wherein the actuator (28) is configured to push the cam piece (20) alternately back and forth between the first and second positions in a case of successive electrical controls with a same polarity; and an electronic control device (30) which has exactly one output for the actuator (28) and via which the successive electrical controls of the actuator (28), which are carried out with the same polarity, take place; wherein the actuator (28) is configured as a linear actuator which has a coil (34) which is supplyable with electrical current and one armature (36) which, by supplying the coil with electrical current, is moveable translationally relative to the coil; wherein the armature (36) is coupled to a control element (40) which is moveable with the armature (36) in a translational manner relative to the coil (34); wherein a forced guide (42), via which rotations of the control element (40) resulting from translational movements of the control element (40) around a rotational axis (44) can be effected; wherein the actuator (28) has a first actuating element (46) and a second actuating element (48) which are each moveable in a translational manner along an actuating direction (50), wherein the control element (40), during its translational movements caused by the successive electrical controls and as a result of its rotations caused by the forced guide (42), alternately actuates the first and second actuating elements (46, 48), thereby alternately moving the actuating elements (46, 48) translationally along the actuating direction (50) and thereby causing the alternating back and forth movement of the cam piece (20).

12. The valve drive device (10) according to claim 11, wherein: the first actuating element (46) has a first actuating surface (52) which runs obliquely to the actuating direction (50) and obliquely to the axial direction (22) of the camshaft (12); and the second actuating element (48) has a second actuating surface (54) which runs obliquely to the actuating direction (50) and obliquely to the axial direction (22) of the camshaft (12); and further comprising: a sliding element (56) displaceable in the axial direction (22) of the camshaft (12) relative to the shaft element (18) and via which the cam piece (20) is displaceable relative to the shaft element (18); wherein the sliding element (56) has a third actuating surface (68) which corresponds to the first actuating surface (52) and which runs obliquely to the actuating direction (50) and obliquely to the axial direction (22) of the camshaft (12); wherein the sliding element (56) has a fourth actuating surface (70) corresponding to the second actuating surface (54) and which runs obliquely to the actuating direction (50) and obliquely to the axial direction (22) of the camshaft (12); wherein the first actuating surface (52) is moveable into supporting contact with the third actuating surface (68) by actuating the first actuating element (46), whereby the sliding element (56) is displaceable relative to the shaft element (18) in a first sliding direction (64) running along the axial direction (22) of the camshaft (12) in order to cause a displacement of the cam piece (20) from one of the positions to the other position via the sliding element (56); wherein the second actuating surface (54) is moveable into supporting contact with the fourth actuating surface (70) by actuating the second actuating element (48), whereby the sliding element (56) is displaceable relative to the shaft element (18) in a second sliding direction (66) running along the axial direction (22) of the camshaft (12) and opposed to the first sliding direction (64) in order to thereby cause displacement of the cam piece (20) from the other position to the one position via the sliding element (56); wherein when one of the actuating elements (46, 48) is actuated by the control element (40), the actuation of the respective other actuating element (48, 46) caused by the control element (40) does not occur.

13. The valve drive device (10) according to claim 12, wherein the control element (40) has a recess (72a) which is arranged in overlap with the first actuating element (46) in a first rotational position of the control element (40) rotatable into the first rotational position by the forced guide (42) and in overlap with the second actuating element (48) in a second rotational position of the control element (40) rotatable into the second rotational position by the forced guide (42).

14. The valve drive device (10) according to claim 11, wherein the forced guide (42) comprises the coil (34) designed as a spring element, which is tensionable by the respective translational movement of the control element (40) caused by the respective electrical control and is thereby rotatable in a first direction of rotation, relaxes between two successive ones of the electrical controls in each case, thereby independently turns back in a second direction of rotation (84) opposed to the first direction of rotation and thereby causes the control element (40) to rotate around the rotational axis (44).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 sectionally, is a schematic and partially cut side view of a valve drive device according to the invention, in particular for an internal combustion engine;

[0029] FIG. 2 is a schematic top view of a control element of the valve drive device;

[0030] FIG. 3 is a schematic and enlarged depiction of a region of the valve drive device designated B in FIG. 1;

[0031] FIG. 4 sectionally, is a further schematic and partially cut side view of the valve drive device;

[0032] FIG. 5 is a further schematic top view of the control element; and

[0033] FIG. 6 sectionally is a further schematic and partially cut side view of the valve drive device.

DETAILED DESCRIPTION OF THE DRAWINGS

[0034] In the Figures, identical or functionally identical elements are provided with identical reference numerals.

[0035] In a schematic and partially cut side view, FIG. 1 shows a valve drive device 10, in particular for an internal combustion engine. The internal combustion engine is designed, for example, as a reciprocating piston engine and is a component of a drive train of a motor vehicle, which is designed, for example, as a passenger vehicle, and can be driven by means of the drive train, in particular by means of the internal combustion engine. The internal combustion engine has at least one combustion chamber which is designed in particular as a cylinder and to which, for example, at least one valve designed as a gas exchange valve is assigned. The valve can be moved translationally between a closed position and several open positions and can—as will be explained in more detail below—be actuated by means of the valve drive device 10, which is simply also referred to as a valve drive, i.e., in particular can be moved translationally from the closed position into the respective open positions.

[0036] The valve drive device 10 comprises at least one camshaft 12, which for example is mounted on a bearing device 14 so as to be rotatable around a rotational axis 16 relative to the bearing device 14. The bearing device 14 is, for example, a housing of the valve drive device, wherein the housing can be, for example, a cylinder head or a cylinder head cover of the internal combustion engine. The internal combustion engine has, for example, an output shaft designed in particular as a crankshaft, which is coupled to the camshaft 12, for example via a control drive. The control drive can be designed as a chain drive, belt drive or gear drive, for example.

[0037] The camshaft 12 comprises a shaft element 18 and at least one cam piece 20 which can be driven by the shaft element 18 and is arranged, for example, on the shaft element 18. The cam piece 20, for example, is connected to the shaft element 18 in a rotationally fixed manner, but can be displaced in the axial direction of the camshaft 12 relative to the shaft element 18. The axial direction of the camshaft 12 coincides with the rotational axis 16, for example, and is illustrated in FIG. 1 by a double arrow 22. The cam piece 20 has at least one first cam 24 which causes a stroke of the first valve and at least one second cam 26 which causes a second stroke of the valve different from the first stroke. Here, the first stroke is greater than the second stroke. The cam piece 20 can be displaced in the axial direction of the camshaft 12 relative to the shaft element 18 between at least one first position shown in FIG. 1 and at least one second position shown in FIG. 6. In the first position, the valve can be actuated by means of the first cam 24. In the second position, the valve can be actuated by means of the second cam 26. In other words, when the cam piece 20 is in the first position shown in FIG. 1 and the camshaft 12 is driven and thereby rotated around the rotational axis 16 relative to the bearing device 14, the valve is actuated by means of the first cam 24. The valve is moved from the closed position to a first of the open positions, wherein the valve carries out the first stroke.

[0038] However, if the cam piece 20 is in the second position shown in FIG. 6 and if the camshaft 2 is driven and thus rotated around the rotational axis 16 relative to the bearing device 14, the valve is actuated by means of the second cam 26 and thus moved from the closed position into a second of the open positions. In doing so, the valve carries out the second stroke, which is shorter than the first stroke, such that, for example, the second open position lies between the first open position and the closed position. In the first position, the valve is not actuated by the second cam 26, wherein in the second position, the valve is not actuated by the first cam 24. In addition, FIG. 1 shows a valve axis 11, along which the valve can be moved translationally between the closed position and the open positions and is actuated by the respective cam 24 or 26 and thus moved translationally. The valve drive (valve drive device 10) further comprises an electrically controllable actuator 28, by means of which the cam piece 20 can be displaced relative to the shaft element 18 in the axial direction of the camshaft 12 as a result of a respective electrical control of the actuator 28. The valve drive further comprises an electronic control device 30 which is depicted particularly schematically in FIG. 1 and by means of which the actuator 28 can be electrically controlled or is electrically controlled within the scope of a method for operating the valve drive device 10. The respective electrical actuation is to be understood in particular as meaning that the actuator 28 is supplied with electrical energy or with electrical current during the respective electrical control, which is conducted into the actuator 28 or flows through it. This means that, during the respective electrical control, the actuator 28 is supplied with electrical energy from the control device 30.

[0039] In order to be able to move the cam piece 20 in a particularly space-saving and cost-effective manner and in a particularly functionally reliable manner, and thus to be able to implement a stroke changeover, also referred to as a valve stroke changeover, in a safe, space-saving and cost-effective manner, the actuator is designed to move the cam piece 20 alternately between the positions in the event of successive electrical actuations of the actuator 28 occurring with the same polarity. For this purpose, the control device 30 has exactly one output 32 for the actuator 28, via which the successive electrical actuations of the electrically operable actuator 28 with the same polarity occur. In other words, the control device 30 controls the actuator 28 only via exactly one output 32, in order to displace the cam piece 20 between the positions.

[0040] In the exemplary embodiment illustrated in the Figures, the actuator 28 is designed as a linear actuator, which has exactly one coil 34. The coil 34 can be supplied with electric current by the respective electrical control. In other words, the electric current with which the actuator 28 is supplied via the output 32 from the control device 30 flows through the coil 34. Since the electrical controls are always carried out with identical or the same polarity, the electric current flows in the electrical controls in each case in the same direction of current flow through the coil 34 and thus through the actuator 28.

[0041] The coil 34 is also referred to as magnetic coil, since by supplying the coil 34 with electric current, at least one magnetic field is generated and provided by the coil 34. Supplying the coil 34 with electric current is also referred to as energizing. If the respective electrical control ends, i.e., the energizing ends, no electrical current flows through the coil 34 between the end of the respective electrical control and before a start of the respective next electrical control, such that the coil 34 is not energized or is in an unenergized state.

[0042] In addition, the linear actuator (actuator 28) has exactly one armature 36, which can be translationally moved relative to the coil 34 by energizing the coil 34, i.e., by supplying the coil 34 with electric current, by means of the coil 34. The armature 36 is also referred to as a magnetic armature, which can be moved translationally by means of the magnetic field. In FIG. 1, an arrow illustrates a so-called armature direction in which the armature 36 is moved when the coil 34 is energized. By energizing the coil 34, the armature 36 is moved, for example, from a starting position shown in FIG. 4 to an actuating position shown in FIG. 1 and thereby in the armature direction (arrow 38). The armature direction runs in the direction of the camshaft 12 such that the armature 36 is moved in the direction of the camshaft 12 or in the direction of the cam piece 20 and thus towards the cam piece 20 when the armature 36 is moved from the starting position into the actuating position.

[0043] The actuator 28 further comprises a control element in the form of a control disc 40, which is shown in FIGS. 2 and 5 in a respective top view. The control disc 40 is coupled to the armature 36 and is in particular attached to the armature 36. As a result, the control disc 40 with the armature 36 can be moved relative to the coil 34 and relative to the camshaft 12. If, for example, the armature 36 is moved in the armature direction (arrow 38) and thus, for example, from the starting position to the actuating position, the control disc 40 is also moved in the armature direction and thus from the starting position to the actuation direction. Thus the control disc 40 is also moved towards the cam piece 20. By way of example, the armature direction runs at least substantially perpendicularly to the axial direction of the camshaft 12.

[0044] The valve drive device 10 also comprises a forced guide 42, the function and components of which are explained in more detail below. By means of the forced guide 42, rotations of the control disc 40 resulting from translational movements of the control disc 40 and relative to the camshaft 12 around a rotational axis 44 can be effected. This means that the forced guide 42 converts, for example, translational movements of the control disc 40 around the rotational axis 44. The respective electrical control thus not only causes a translational movement of the control disc 40 from the starting position into the actuating position, but with the aid of the forced guide 42, the respective electrical control also results in a rotation of the control disc 40 around the rotational axis 44.

[0045] The actuator 28 comprises at least one first actuating element 46 and at least one second actuating element 48, which are designed as pins or as bolts in the present case, for example. The respective actuating element 46 or 48 can be moved translationally relative to the camshaft 12 along or in an actuating direction illustrated in FIG. 1 by an arrow 50. It can be seen from FIG. 1 that the actuation direction corresponds to the armature direction or runs parallel to the armature direction or coincides with the armature direction, wherein the actuation direction runs, for example, at least substantially perpendicularly to the axial direction of the camshaft 12. The control disc 40 alternately actuates the actuating elements 46 and 48 during its translational movements caused by the successive electrical controls and as a result of its rotations caused by means of the forced guide 42, whereby the actuating elements 46 and 48 are alternately moved translationally in the actuating direction relative to the camshaft 12 during the successive electrical controls, in particular moved towards the camshaft 12, such that the control disc 40 causes the alternating back and forth movement of the cam piece 20. This is also explained in more detail below. The first actuating element 46 has a first actuating surface 52, which runs obliquely to the actuating direction and obliquely to the axial direction of the camshaft 12. The second actuating element 48 has a second actuating surface 54, which runs obliquely to the actuating direction and obliquely to the axial direction of the camshaft 12.

[0046] The valve drive device 10, in particular the actuator 28, comprises a sliding element in the form of a sliding carriage 56 which is displaceable in the axial direction of the camshaft 12 relative to the shaft element 18, by means of which the cam piece 20 can be moved back and forth between the positions relative to the shaft element 18. For this purpose, the cam piece 20 has, for example, a first positive-locking element 58, which is designed in particular as a disc and interacts, for example, positively with at least one second positive-locking element 60 of the sliding carriage 56. In this case, the positive-locking element 60 is designed as a receptacle or the positive-locking element 60 has a receptacle 62 in which the positive-locking element 58 engages. If, for example, the sliding carriage 56 is thus displaced relative to the shaft element 18 in a first sliding direction coinciding with the axial direction and illustrated in FIG. 1 by an arrow 64, the sliding carriage 56 takes the cam piece 20 with it, such that the cam element 20 is also displaced in the first sliding direction relative to the shaft element 18. If, in contrast, the sliding carriage 56 is displaced in a second sliding direction opposed to the first sliding direction and illustrated in FIG. 1 by an arrow 66 relative to the shaft element 18, the sliding carriage 56 takes the cam piece 20 with it such that the cam piece 20 is also displaced in the second sliding direction relative to the shaft element 18. By displacing the cam piece 20 in the first sliding direction, for example, the cam piece 20 can be displaced from the first position to the second position. By displacing the cam piece 20 in the second sliding direction, for example, the cam piece can be displaced from the first position to the second position.

[0047] Here, the sliding carriage 56 has a third actuating surface 68 corresponding to the first actuating surface 52, which runs obliquely to the actuating direction obliquely to the axial direction of the camshaft 12. In addition, the sliding carriage 56 has a fourth actuating surface 70 corresponding to the second actuating surface 54, which runs obliquely to the actuating direction and obliquely to the axial direction of the camshaft 12. The first actuating surface 52 is moveable by actuating the first actuating element 46 in supporting contact with the third actuating surface 68, whereby the sliding carriage 56 is displaced in the first sliding direction along the axial direction of the camshaft 12 relative to the shaft element 18, in order to cause a displacement of the cam piece 20 from the first position to the second position via the sliding carriage 56.

[0048] The second actuating surface 54 is moveable by actuating the second actuating element 48 in supporting contact with the fourth actuating surface 70, whereby the sliding carriage 56 is displaced relative to the shaft element 18 in the second sliding direction extending along the axial direction of the camshaft 12 and opposed to the first sliding direction, whereby a displacement of the cam piece 20 from the second position to the first position via the sliding carriage 56 is caused. When one of the actuating elements 46 and 48 is actuated by the control disc 40, the other actuating element 48 or 46, respectively, is not actuated by the control disc 40, such that the cam piece 20 is always pushed into only one of the sliding directions.

[0049] It can be recognized particularly well from FIGS. 2 and 5 that the control disc 40 has a plurality of recesses 72a-c, which are each designed as through-openings, for example. In the circumferential direction of the control disc 40, the recesses 72a-c are arranged one behind the other or one after the other and are spaced apart from one another, wherein the recesses 72a-c are evenly distributed in the circumferential direction of the control disc 40. In the exemplary embodiment illustrated in the Figures, the control disc 40 has exactly three recesses 72a-c, which, because the recesses 72a-c are evenly distributed in the circumferential direction of the control disc 40, are spaced apart in pairs by 120 degrees, in particular running around the rotational axis 44. In the circumferential direction of the control disc 40, respective wall regions 74a-c of the control disc 40 are arranged between the respective recesses 72a-c, wherein the wall regions 74a-c at least partially delimit the recesses 72a-c in each case.

[0050] FIGS. 1 and 2 show, for example, a first rotational position of the control disc 40, which can be rotated into the first rotational position by means of the forced guide 42. In the first rotational position, the recess 72a overlaps or overlays the actuating element 46. Furthermore, in the first rotational position, the wall region 74c overlaps or overlays the actuating element 48. If the armature 36 and with it the control disc 40 are then moved from the starting position into the actuating position and thus into the actuating direction or into the armature direction, the actuating element 46 dips into or through the recess 72a. In other words, the actuating element 46 is arranged in the recess 72a. Again expressed in other words, the actuating element 46 engages in the recess 72a, in particular in such a way that actuation of the actuating element 46 by the control disc 40 does not occur. The wall region 74c, however, comes into supporting contact with the actuating element 48 or the actuating element 48 is actuated by means of the wall region 74c and is thus moved in the actuating direction. As a result, the actuating surface 54 comes into supporting contact with the actuating surface 70, such that the actuating surface 54 slides on the actuating surface 70 or vice versa. As a result, the sliding carriage 56 and with it the cam piece 20 are displaced in the second sliding direction relative to the shaft element 18, whereby, for example, the cam piece 20 is pushed into the first position shown in FIG. 1, in particular starting from the second position.

[0051] If, for example, starting from the first rotational position shown in FIG. 2, the control disc 40 is rotated by 180 degrees around the rotational axis 44 relative to the camshaft 12, the control disc 40 will, for example, reach a second rotational position. In the second rotational position, the recess 72a overlaps or overlays the actuating element 48, and the wall region 74c overlaps or overlays the actuating element 46. If, for example, the armature 36 and with it the control disc 40 are then moved from the starting position into the actuating position and thus into the armature direction or into the actuating direction, the actuating element 48 dips into the recess 72a in such a way that the actuation of the actuating element 48 by the control disc 40 is not effected. The actuating element 46, however, is actuated by means of the wall region 74c and is thereby moved translationally in the actuating direction. As a result, the actuating surface 52 comes into supporting contact with the actuating surface 68, such that the actuating surface 52 slides on the actuating surface 68 or vice versa. As a result, the sliding carriage 56 and with it the cam piece 20 are displaced in the first sliding direction relative to the shaft element 18, whereby the cam piece 20 is displaced from the first position to the second position relative to the shaft element 18. By means of the forced guide 42, the control disc 40 is moved into respective rotational positions during its respective movements from the actuating position into the initial position, wherein in the respective rotational position, exactly one of the recesses 72a-c is in overlap with exactly one of the actuating elements 46 and 48 and exactly one of the wall regions 74a-c is in overlap with the respective other of the actuating elements 46 and 48. The first rotational position described above and the second rotational position described above belong to the rotational positions in which the control disc 40 can be rotated or is rotated by means of the forced guide 42. Thus, during a respective translational movement of the control disc 40 from the initial position into the actuating position, exactly one of the actuating elements 46 and 48 is actuated, while an actuation of the other actuating element 48 or 46 does not occur. In this way, the cam piece 20 can easily be moved back and forth.

[0052] The forced guide 42 comprises at least one spring element, which, in the present case, is formed by the coil 34. The spring element (coil 34), for example, is supported on the one side or on the one end at least indirectly, in particular directly, on the housing 14. On the other side or on the other end, the spring element is supported, for example, at least indirectly, in particular directly, on the control disc 40. The control disc 40 can be moved translationally relative to the housing along the armature direction or along the actuating direction. If the control disc 40 is now moved translationally along the armature direction and thus from the initial position to the actuating position, the spring element is tensioned. In the exemplary embodiment illustrated in the Figures, the spring element (coil 34) is compressed. The spring element is designed as a coil spring, for example, which is twisted or rotated by the tensioning or compression of the spring element. This means in particular that the respective ends of the spring element are rotated relative to one another, in particular around the rotational axis 44. The spring element is thus more strongly tensioned in the actuating position than in the starting position, such that the spring element provides a spring force at least in the actuating position which acts at least indirectly, in particular directly, on the control disc 40. After the end of the electrical control and before the start of the next electrical control, the spring element can be at least partially released, whereby the control disc 40 and with it the armature 36 are moved from the actuating position back to the starting position by means of the releasing spring element or by means of the spring force.

[0053] In this case, the control disc 40 and the armature 36 are moved translationally in a reset direction opposed to the armature direction or in a reset direction opposed to the armature direction or the actuating direction and illustrated in FIG. 1 by an arrow 76, in particular relative to the camshaft 12 and away from the camshaft 12. The reset direction is also referred to as reverse direction. When the spring element is released, the spring element turns back automatically. In other words, when the spring element is tensioned, its ends are rotated relative to each other in a first direction of rotation. When the spring element is released, the spring element automatically turns back in a second direction of rotation opposed to the first direction of rotation, such that the ends rotate relative to each other in the second direction of rotation opposed to the first direction of rotation. As a result, the spring element or the forced guide 42 causes the control disc 40 to rotate around the rotational axis 44, in particular in the second direction of rotation. A rotation of the control disc 40 in the first direction of rotation caused by the forced guide 42 does not occur, although the ends of the spring element are rotated relative to each other in the first direction of rotation when the spring element is tensioned, since the spring element is coupled to or interacts with the control disc 40, for example, via a freewheel device 78 which can be seen in FIG. 3 and is also referred to as a freewheel. The freewheel device 78 comprises a toothing 80, for example designed as micro-toothing, which is provided on the control disc 40, in particular on a side 82 of the control disc 40 facing the spring element (coil 34). Here, the side 82 is a broad side of the control disc 40 assigned to the spring element.

[0054] The stroke changeover which can be effected by means of the valve drive device 10 is explained in summary below: according to FIG. 1, the coil 34, for example, is first energized and thus tightens the armature 36 and the control disc 40 attached to it, such that the coil 34 or the magnetic field generated by the coil 34 holds the armature 36 and the control disc 40 in the actuating position against the spring force provided by the spring element. Since the control disc 40 has the recesses 72a-c, which are, for example, formed as slots, and the recess 72a overlaps with the actuating element 46, only the actuating element 48, which is for example formed as a transmission bolt, or is actuated by means of the control disc 40, while actuation of the actuating element 46, which is for example formed as a transmission bolt, effected by the control disc 40 does not occur. The cam piece 20 is in the first position, such that the valve is impinged upon or actuated by means of the cam 24.

[0055] FIG. 2 shows the first rotational position of the control disc 40, which assumes the first rotational position, for example in FIG. 1. Based on FIG. 1, the energization of the coil 34 is switched off, for example. Before the beginning of the next electrical control and thus before the beginning of the next energizing of the coil 34, the coil is thus de-energized, which is depicted in FIG. 4. Since the coil 34 acts as a spring element, the coil 34 lifts, for example, the control disc 40 after the end of the energization and before the beginning of the next energization and accepts, for example, the armature 36 magnetically held thereon and moves it from the actuating position into the starting position shown in FIG. 4. Due to the releasing of the coil 34 (spring element or coil spring) which takes place in this process and is also referred to as expansion, the ends of the coil spring rotate relative to each other in the second direction of rotation. Since one of the ends of the spring element is housing-fixed, i.e., fixed to the housing, the other end of the spring element rotates in the second direction of rotation relative to the one end, whereby the other end rotates the control disc 40 around the rotational axis 44 in the second direction of rotation relative to the camshaft 12 via the toothing 80, in particular if the actuating element 36 emerges from the recess 72a as a result of the movement of the control disc 40 in the direction of the initial position, whereby the control disc 40 is no longer guided via the recess 72a and the actuating element 46. This means, for example, that as long as the actuating element 46 engages in the recess 72a, the control disc 40 is secured against rotation around the rotational axis 44. If the actuating elements 46 and 48 are arranged completely outside the recesses 72a-c, the rotation of the control disc 40 around the rotational axis 44 in the second direction of rotation can be effected by the forced guide 42, in particular by the spring element. According to FIG. 4, the cam piece 20 is still in the first position such that the valve is still actuated by means of the first cam 24.

[0056] FIG. 5 shows, for example, a third rotational position of the control disc 40, wherein this third rotational position also belongs to the rotational positions into with the forced guide 42 of the control disc 40 can rotate. The rotation of the control disc 40 around the rotational axis 44 in the second direction of rotation is illustrated in FIG. 5 by an arrow 84. In the third rotational position, for example, the recess 72b overlaps with the actuating element 48, while the wall region 74a overlaps with the actuating element 46.

[0057] According to FIG. 6, the coil 34 is energized again, whereby the control disc 40 and the armature 36 are moved from the initial position shown in FIG. 4 to the actuating position. As the control disc 40 was previously rotated, the actuating element 48 now dips into the recess 72b, while the actuating element 46 is actuated by means of the wall region 74a. As a result, the actuating surface 52 comes into supporting contact with the actuating surface 68, whereby the sliding carriage 56 and with it the cam piece 20 are pushed in the first sliding direction.

[0058] Since one of the actuating elements 46 and 48 dips into one of the recesses 72a-c in each case during the respective movement of the control disc 40 from the initial position into the actuating position, the control disc 40 is secured against rotation around the rotational axis 44 during its movement from the initial position into the actuating position. In other words, the control disc 40 cannot rotate during its movement into the actuating position. However, the ends of the spring element are rotated relative to each other, but the other end of the spring element slides over at least one tooth of the toothing 80. This does not prevent the ends of the spring element from rotating relative to each other in the first direction of rotation. When the spring element is released, the other end comes, for example, into supporting contact with at least one tooth of the toothing 80, whereby the spring element can exert a torque on the control disc 40 via its other end when the spring element is released. By means of this torque, when the actuators 46 and 48 do not engage in the recesses 72a-c, the control disc 40 is rotated around the rotational axis 44 in the second direction of rotation. In this way, the control disc 40 can be successively rotated around the rotational axis 44 in the second direction of rotation from rotational position to rotational position by means of the forced guide 42, in which one of the recesses 72a-c of one of the actuating elements 46 and 48 and one of the wall regions 74a-c of one of the actuating elements 46 and 48 overlap in each case. In FIG. 6, it can be seen that the valve drive has been switched over such that the valve is now operated by means of the second cam 26.

[0059] On the whole, it can be seen that the actuator 28 is designed as an electromechanical linear actuator with only one coil 34 and only one armature 36. The armature 36 or the control disc 40 can actuate the two actuating elements 46 and 48, which are designed as bolts, for example. Each time the coil 34 is energized, the armature 36 is tightened. After the end of the energization and before the beginning of the next energization, the armature 36 or the control disc 40 performs a return stroke, in the scope of which the control disc 40 and the armature 36 move from the actuating position back to the starting position. During the return stroke, the control disc 40 is rotated by an angular amount and around the rotational axis 44 relative to the camshaft 12 via the forced guide 42, which is designed as a mechanism, for example, such that only one of the actuating elements 46 and 48 is actuated alternately in the successive electrical controls. The respective actuating element 46 or 48 presses, for example, on the sliding carriage 56, also referred to as the slide, in order to move the cam piece 20 by means of the slide.

LIST OF REFERENCE CHARACTERS

[0060] 10 valve drive device [0061] 11 valve axis [0062] 12 camshaft [0063] 14 bearing device [0064] 16 rotational axis [0065] 18 shaft element [0066] 20 cam piece [0067] 24 first cam [0068] 26 second cam [0069] 28 actuator [0070] 30 control device [0071] 32 output [0072] 34 coil [0073] 36 armature [0074] 38 arrow [0075] 40 control disc [0076] 42 forced guide [0077] 44 rotational axis [0078] 46 actuating element [0079] 48 actuating element [0080] 50 arrow [0081] 52 actuating surface [0082] 54 actuating surface [0083] 56 sliding carriage [0084] 58 positive-locking element [0085] 60 positive-locking element [0086] 62 receptacle [0087] 64 arrow [0088] 66 arrow [0089] 68 actuating surface [0090] 70 actuating surface [0091] 72a-c recess [0092] 74a-c wall region [0093] 76 arrow [0094] 78 freewheel device [0095] 80 toothing [0096] 82 side [0097] 84 arrow