Valve train device

Abstract

A valve train device, in particular for an internal combustion engine, includes a support element secured to a housing, at least one axially moveable cam unit associated with a valve, and at least one switch unit for axially moving at least one part of the cam unit having at least one displacement body which is provided to be introduced for axial movement at least functionally between the support element and the cam unit. The cam unit has at least three cam paths.

Claims

1. A valve train device, comprising: a support element secured to a housing; an axially shiftable cam unit that is associated with a valve; a switch unit for axially shifting the cam unit, wherein the switch unit has a first displacement body and a second displacement body; wherein the cam unit has a first cam track, a second cam track, and a third cam track; wherein the first cam track and the second cam track are engageable with the valve when the switch unit is in a first switch position; wherein the first displacement body and the second displacement body are separable from the cam unit at a same time in a switch preparation for activating and/or deactivating the third cam track; and a shifting element, wherein the switch unit is axially adjustable with respect to the support element by the shifting element into a second switch position in which the third cam track is engageable with the valve.

2. The valve train device according to claim 1, wherein the shifting element is disposed inside the switch unit.

3. The valve train device according to claim 2, wherein the shifting element axially shifts the first displacement body and the second displacement body inside the switch unit.

4. The valve train device according to claim 1, wherein the shifting element is disposed outside the switch unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic representation of a valve train device according to the invention in a first embodiment comprising a cam unit in a second switch position;

(2) FIG. 2 is a schematic representation of the valve train device comprising the cam unit in a third switch position,

(3) FIG. 3 is a schematic representation of the valve train device comprising the cam unit in a second switch position together with a switch unit in an intermediate position;

(4) FIG. 4 is a schematic representation of the valve train device comprising the cam unit in a second switch position together with the switch unit in a second switch position;

(5) FIG. 5 is a schematic representation of the valve train device comprising the cam unit in a first switch position together with the switch unit in the second switch position; and

(6) FIG. 6 is a schematic representation of a valve train device according to the invention in a second embodiment comprising a cam unit in a third switch position and a switch unit in a first switch position.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) FIGS. 1 to 5 are schematic representations of a valve train device according to the invention. The valve train device is part of an internal combustion engine (not shown in more detail). The internal combustion engine is designed as a motor vehicle internal combustion engine, which is provided to convert chemical energy into kinetic energy, which is used in particular for propulsion of a motor vehicle. The internal combustion engine in this case has a plurality of cylinders, each having a plurality of valves 16, 17. The internal combustion engine has two valves 16, 17 designed as intake valves and two valves designed as exhaust valves. In principle, it is also conceivable that the internal combustion engine has a different number of valves 16, 17. The valves 16, 17 are shown schematically by their actuation level in FIG. 1-5.

(8) The valve train device is provided for actuating the valves 16, 17 of the internal combustion engine. The valve train device has a camshaft 10 for actuating the valves 16, 17. In FIG. 1, only a part of the camshaft 10 that is associated with a cylinder is shown. The camshaft 10 is mounted in a support element 14 that is secured to the housing. In principle, it is also conceivable that the support element 14 is designed as a housing of the valve train device. Furthermore, the valve train device has a further camshaft which is not shown in more detail. The camshaft 10 shown is designed, by way of example, as an intake camshaft and the camshaft which is not shown in more detail as an exhaust camshaft. In the following, only the part of the camshaft 10 described in FIG. 1 will be described in more detail. The description can be transferred to the part of the camshaft 10 not shown in more detail and to the camshaft not shown in more detail.

(9) The camshaft 10 is rotatably mounted in a valve train housing which is not shown in more detail. The camshaft 10 is mounted so as to rotate about a rotational axis 11. The rotational axis 11 of the camshaft 10 is oriented so as to be substantially parallel to a rotational axis of a crankshaft of the internal combustion engine. The camshaft 10 is driven by means of a coupling (not shown in more detail) of the crankshaft. The valve train device comprises one cam unit 12 per cylinder. In principle, it is also conceivable that the valve train device has a different number of cam units 12 per cylinder. The cam unit 12 is formed by a cam element 13. In principle, it is also conceivable that the cam unit 12 is formed by a plurality of cam elements 13.

(10) The cam element 13 is arranged so as to be axially shiftable on the camshaft 10. In this case, the cam element 13 is coupled to the camshaft 10 for conjoint rotation. The cam element 13 is connected to the camshaft 10 in particular by means of teeth (not shown in more detail). The cam element 13 is provided for actuating the valves 16, 17. The cam element 13 has three cam tracks 18, 19, 20, 18′, 19′, 20′ for each valve 16, 17. In principle, it is also conceivable that the cam element 13 has only two or more than three cam tracks 18, 19, 20, 18′, 19′, 20′ for each valve 16, 17. The cam tracks 18, 19, 20, 18′, 19′, 20′ each have different contours and thus actuate the relevant valve 16, 17 with correspondingly different valve lifts. In a first switch position of the cam element 13, the first cam tracks 18, 18′ actuate the relevant valve 16, 17. In a second switch position of the cam element 13, the second cam tracks 19, 19′ actuate the relevant valve 16, 17. In a third switch position of the cam element 13, the third cam tracks 20, 20′ actuate the relevant valve 16, 17. The actuation of a valve 16, 17 by a cam track 18, 19, 20, 18′, 19′, 20′ takes place in a manner known to a person skilled in the art.

(11) In order to adjust the cam element 13 on the camshaft 10 between the three switch positions, the valve train device has a switch unit 15. The switch unit 15 is provided to shift the cam element 13 axially on the camshaft 10 in order to bring the different cam tracks 18, 19, 20, 18′, 19′, 20′ into engagement with the relevant valve 16, 17. In this case, the switch unit 15 is provided to adjust the cam element 13 between the switch positions using a displacement principle. The switch unit 15 is provided to adjust the cam element 13 by means of a displacement, in particular orthogonally to an actuating direction of the switch unit 15.

(12) The switch unit 15 comprises a displacement body 21 for axially shifting the cam element 13 in a first switching direction 23. The displacement body 21 is provided to displace at least part of the cam unit 12 in order to axially shift the cam unit 12. In order to axially shift the cam element 13, the displacement body 21 is provided to be introduced operatively between the support element 14 and the cam element 13. The displacement body 21 has a width which corresponds to a shift path of the cam element 12 between two switch positions of immediately adjacent cam tracks 18, 19, 20, 18′, 19′, 20′. The width of the displacement body 21 corresponds to a width of a cam path 18, 19, 20, 18′, 19′, 20′. The cam element 13 forms a displacement contour 22, which is designed so as to correspond to the displacement body 21. The displacement contour 22 is provided so that the displacement body 21 for adjusting the cam element 13 comes into frictional contact therewith. The displacement contour 22 is designed as an edge of a groove 29 in the cam element 13. In this case, the circumferential groove 29 has a width that corresponds to the width of the displacement body 21. The displacement body 21 has an oblique contact surface 27. When the displacement body 21 operatively slides in, the oblique contact surface 27 of the displacement body 21 touches the cam element 13 first. The displacement body 21 has a wedge shape which forms the oblique contact surface 27. When the displacement body 21 slides in toward the cam element 13 in the radial direction, the oblique contact surface 27 engages laterally against the displacement contour 22 of the cam element 13. When the displacement body 21 slides in further, the cam element 12 slides off the oblique contact surface 27 and is shifted by the displacement body 21 in the first switching direction 23. In a switching process, the oblique contact surface 27 of the displacement body 25 is pressed against the displacement contour 22 of the cam element and thereby displaces the cam element 13 in one of the first switching directions 23.

(13) The switch unit 15 comprises a further displacement body 25 for axially shifting the cam element 13 in a second switching direction 24. The second switching direction 24 is opposite to the first switching direction. The displacement body 25 is provided to displace at least part of the cam unit 12 for axial displacement of the cam unit 12. In order to axially shift the cam element 13, the displacement body 25 is provided to be introduced operatively between the support element 14 and the cam element 13. The displacement body 25 has a width which corresponds to a shift path of the cam element 12 between two switch positions, of immediately adjacent cam tracks 18, 19, 20, 18′, 19′, 20′. The width of the displacement body 25 corresponds to a width of a cam path 18, 19, 20, 18′, 19′, 20′. The cam element 13 forms a second displacement contour 26, which is designed so as to correspond to the displacement body 25. The displacement contour 26 is provided so that the displacement body 25, in order to adjust the cam element 13, comes into frictional contact therewith in the second switching direction 24. The displacement contour 26 is designed as an edge of a groove 30 in the cam element 13. In this case, the circumferential groove 30 has a width that corresponds to the width of the displacement body 25. The displacement body 25 has an oblique contact surface 28. When the displacement body 25 operatively slides in, the oblique contact surface 28 of the displacement body 25 touches the cam element 13 first. The displacement body 25 has a wedge shape which forms the oblique contact surface 28. In this case, the oblique contact surface 28 of the second displacement body 25 is mirror-symmetrically oriented with respect to the oblique contact surface 27 of the first displacement body 21. In a switching process, the oblique contact surface 28 of the displacement body 25 is pressed against the displacement contour 22 of the cam element and thereby displaces the cam element 13 in one of the second switching directions 24.

(14) In an operating state in which the cam element 13 is not shifted axially between the switch positions thereof, the displacement bodies 21, 25 each form a thrust bearing for the cam element 13. In designing the thrust bearing for the cam element 13, the displacement bodies 25, 26 each form axial stops for the cam element 13, in which they are arranged in the corresponding groove 29, 30 in the cam element 13. In principle, it is also conceivable that the displacement bodies 21, 25 and the corresponding displacement contours 22, 26 are designed in another way that a person skilled in the art deems appropriate. It is conceivable, for example, that the displacement contours 22, 26 are designed as ribs having an oblique contact surface. In this case, the displacement bodies 21, 25 would be designed to be correspondingly equivalent.

(15) The displacement bodies 21, 25 are designed to be uncoupled. The displacement bodies 21, 25 are designed in particular to be switchable independently of each other. The switch unit 15 comprises an actuator 31. The actuator 31 is provided for actuating the two displacement bodies 21, 25. The switch unit 15 comprises an actuator 32. The actuator 31 of the switch unit 15 is arranged inside the housing. The displacement bodies 21, 25 are mounted so as to be shiftable in the housing 32. The displacement bodies 21, 25 can be shifted linearly in a radial direction. In a state in which the displacement bodies 21, 25 are operatively introduced into the cam element 13, the displacement bodies 21, 25 are accommodated 60 percent in the housings 31, 32. In order to adjust the displacement bodies 21, 25, the actuator 31 comprises two switch actuators 33, 34 for radially moving the displacement bodies 21, 25. The switch actuators 33, 34 are schematically indicated by the respective switching directions thereof, which each extend in the radial direction. The switch actuators 33, 34 are designed as actuators that a person skilled in the art deems appropriate. The switch actuators 33, 34 are provided to adjust the displacement bodies between two switch positions. In a first switch position, the displacement bodies 21, 25 engage the corresponding displacement contour 22, 26 of the cam element 13. In a second switch position, the displacement bodies 21, 25 are spaced apart from the corresponding displacement contour 22, 26 of the cam element 13.

(16) The valve train device has a shifting element 35. The shifting element 35 is provided to adjust at least part of the switch unit 15 axially with respect to the support element 14. The shifting element 35 is provided in particular to axially adjust the entire switch unit 15. For this purpose, the switch unit 15 is mounted in the housing of the valve train device so as to be axially shiftable. The switch unit 15 is mounted in the housing of the valve train device by means of a mounting unit (not shown in more detail). The switch unit 15 is mounted so as to be shiftable between two switch positions. FIGS. 1 to 3 show a first switch position of the switch unit 15. FIGS. 4 to 5 show a second switch position of the switch unit 15. For the purpose of switching, the switch unit 15 is provided so as to be axially shifted onto an outer cam track 18, 18′, 20, 20′ of the three cam tracks 18, 19, 20, 18′, 19′, 20′. Using the axial displacement of the switch unit 15, which can perform two mutually opposite switching movements by means of its two displacement bodies 21, 25, a third switch position of the cam element 13 can be achieved. The shifting element 35 is designed as an actuator that comprises an axially retractable actuating lever. In this case, the actuator is designed as an electronically controllable spindle drive. In principle, it is also conceivable that the actuator is designed as a pneumatic or hydraulic actuator.

(17) In order to adjust the cam element into a first switch position in which the third cam tracks 18, 18′ engage the corresponding valve 16, 17, the two displacement bodies 21, 25 are initially switched at the same time to a retracted switch position and thus separated from the cam element 13 of the cam unit 12. As a result, an axial securing of the cam element 13 is released. Subsequently, the switch unit 15 is moved by means of the shifting element 35 in a pre-switch movement to the second switch position thereof. As a result, in order to shift the cam element 13 in the first switching direction 13, the displacement body 21 is in a position with respect to the correspondingly formed displacement contour 22 of the cam element 13, such that the contour can engage in an intended manner in order to switch the cam element 13. After the adjustment of the switch unit 15 into its second switch position, the cam element 13 is switched by introducing the displacement body 21 to the displacement contour 22 of the cam element 13 in the first switching direction 23 and thereby switched to the first switch position. In order to switch the cam element 13 between the first switch position in which the outer cam tracks 18, 18′ are engaged and the third switch position of the cam element 13 in which the outer cam tracks 20, 20′ are engaged, the switch unit 15 is shifted by means of the shifting element 35 in each case in a pre-switch movement axially with respect to the support element 14.

(18) FIG. 6 shows a further embodiment of the invention. The following descriptions and the drawings are substantially restricted to the differences between the embodiments, in which, in principle, reference can also be made, with respect to identically designated components, in particular with respect to components with the same reference signs, to the drawings and/or the description of the other embodiments, in particular FIGS. 1 to 5. To distinguish the embodiments the letter “a” is placed after the reference signs of the embodiment in FIGS. 1 to 5. In the embodiments of FIG. 6 the letter “a” is replaced by the letter “b”.

(19) FIG. 6 schematically shows a valve train device according to the invention in a second embodiment. The valve train device is part of an internal combustion engine (not shown in more detail). The internal combustion engine is designed as a motor vehicle internal combustion engine, which is provided to convert chemical energy into kinetic energy, which is used in particular for propulsion of a motor vehicle. The internal combustion engine has in this case a plurality of cylinders, each having a plurality of valves 16b, 17b. The valve train device is provided for actuating the valves 16b, 17b of the internal combustion engine. The valve train device has a camshaft 10b for actuating the valves 16b, 17b. The camshaft 10b is mounted in a support element 14b that is secured to the housing. In principle, it is also conceivable that the support element 14b is designed as a housing of the valve train device. The camshaft 10b is mounted so as to rotate about a rotational axis 11b. The valve train device comprises one cam unit 12b per cylinder. In principle, it is also conceivable that the valve train device has a different number of cam units 12b per cylinder. The cam unit 12b is formed by a cam element 13b. In principle, it is also conceivable that the cam unit 12b is formed by a plurality of cam elements 13b.

(20) The cam element 13b is arranged so as to be axially shiftable on the camshaft 10b. In this case, the cam element 13b is coupled to the camshaft 10b for conjoint rotation. The cam element 13b is connected to the camshaft 10b in particular by means of teeth (not shown in more detail). The cam element 13b is provided for actuating the valves 16b, 17b. For this purpose, the cam element 13b has three cam tracks 18b, 19b, 20b, 18b′, 19′, 20′ per valve 16b, 17b. The cam unit 12b is substantially the same design as the corresponding cam unit from the first embodiment.

(21) In order to adjust the cam element 13b on the camshaft 10b between the three switch positions, the valve train device has a switch unit 15b. The switch unit 15b comprises a displacement body 21b for axially shifting the cam element 13b in a first switching direction 23b. The displacement body 21b is provided to displace at least part of the cam unit 12 in order to axially shift the cam unit 12. The switch unit 15b comprises a further displacement body 25b for axially shifting the cam element 13b in a second switching direction 24b.

(22) The displacement bodies 21b, 25b are designed to be uncoupled. The displacement bodies 21b, 25b are designed in particular to be switchable independently of each other. The switch unit 15b comprises an actuator 31b. The actuator 31b is provided for actuating the two displacement bodies 21b, 25b. The switch unit 15b comprises a housing 32b. In order to adjust the displacement bodies 21b, 25b, the actuator 31b comprises two switch actuators 33b, 34b for radially moving the displacement bodies 21b, 25b. The switch actuators 33b, 34b are schematically indicated by the respective switching directions thereof, which each extend in the radial direction.

(23) The valve train device has a shifting element 35b. The shifting element 35b is provided to adjust at least part of the switch unit 15b axially with respect to the support element 14b. In contrast to the first embodiment, the shifting element 35b is arranged inside the housing 32b. The shifting element 35b is provided to adjust the two displacement bodies 21b, 25b inside the housing 32b of the switch unit 15b. In FIG. 6, the displacement bodies 21b, 25b are shown in a first switch position and indicated by dashed lines in a second switch position.