SWITCHABLE ACTUATION DEVICE FOR A POPPET VALVE IN AN INTERNAL COMBUSTION ENGINE, INTERNAL COMBUSTION ENGINE AND MOTOR VEHICLE

Abstract

The present invention relates to a switchable actuation device (100) for a gas exchange valve. The switchable actuation device (100) comprises a two-piece rocker arm (10). Said rocker arm comprises a first rocker arm portion (1a), which is mounted pivotably about a rocker arm shaft (2) and to which a bearing sleeve (1a1) is fastened concentrically with the rocker arm shaft (2), and a second rocker arm portion (1b) mounted pivotably on the bearing sleeve (1a1). Furthermore, both the first and the second rocker arm portions (1a, 1b) each comprise a cut-out (3a, 3b), wherein a locking element (4a) of a coupling device (4) of the switchable actuation device (100) can optionally be brought into and out of engagement with the two cut-outs (3a, 3b). An actuation of the poppet valve, preferably a change between a closed position and an open position of the poppet valve, is interrupted if the locking element (4a) is not in engagement with the two cut-outs (3a, 3b). The invention also relates to an internal combustion engine (20) and a motor vehicle (30).

Claims

1-15. (canceled)

16. A switchable actuation device for a poppet valve in an internal combustion engine which is movable indirectly and periodically via a cam of a camshaft between a closed and an open position, comprising: a) a two-piece rocker arm for actuating the poppet valve, comprising: a.sub.1) a first rocker arm portion which is mounted pivotably about a rocker arm shaft and on which a bearing sleeve is attached concentrically with the rocker arm shaft; and a.sub.2) a second rocker arm portion which is mounted pivotably on the bearing sleeve; wherein the first rocker arm portion comprises a first cutout, and the second rocker arm portion comprises a second cutout; and b) a coupling device for releasable, rotationally fixed connection of the first and second rocker arm portions, comprising a locking element which may be brought optionally into and out of engagement with the first and second cutouts, wherein actuation of the poppet valve is interrupted if the locking element is not in engagement with the first or second cutout.

17. The actuation device as claimed in claim 16, wherein the bearing sleeve a) is formed integrally on the first rocker arm portion; and/or b) surrounds the rocker arm shaft concentrically; and/or c) comprises a groove in which a locking ring is inserted for securing the axial position of the second rocker arm portion.

18. The actuation device as claimed in claim 16, wherein by a movement perpendicularly to the rocker arm shaft, the locking element may be brought optionally into a) a release position S.sub.e, in which the locking element is not in engagement with the first and second cutouts, or b) a locking position S.sub.a, in which the locking element is in engagement with the first and second cutouts.

19. The actuation device as claimed in claim 1, wherein a) the first and second cutouts are each formed as a groove extending parallel to the rocker arm shaft, with a groove cross-section which tapers towards the rocker arm shaft; and b) the locking element is formed wedge-shaped and/or frustoconical and/or at least in portions complementary in shape to the first and/or second cutout.

20. The actuation device as claimed in claim 19, wherein each of the groove cross-sections is configured to clamp the locking element in self-locking fashion in the circumferential direction on engagement of the locking element in the first and second cutouts.

21. The actuation device as claimed in claim 19, wherein each of the groove cross-sections is delimited towards the rocker arm shaft by a groove base and at the sides by two groove flanks, wherein a slope angle a of the groove flanks is smaller than a self-locking angle an of the material pairing of the first rocker arm portion and the locking element and/or of the second rocker arm portion and the locking element.

22. The actuation device as claimed in claim 16, wherein the locking element a) has its greatest extent along the rocker arm shaft; and/or b) extends parallel to the rocker arm shaft; and/or c) is movable only perpendicularly to the rocker arm shaft.

23. The actuation device as claimed in claim 16, wherein the coupling device comprises a bearing block for axially fixing the locking element, wherein the bearing block has two bearing cheeks which are spaced apart in the axial direction and on which the locking element is pivotably mounted by means of two pegs attached to the locking element.

24. The actuation device as claimed in claim 23, wherein the pegs of the locking element are each guided in a slot of the bearing cheeks of the bearing block which extends in the circumferential direction.

25. The actuation device as claimed in claim 23, wherein the bearing block comprises a guide roller which is mounted so as to be rotatable in the axial direction and which rests on the locking element in the radial direction for radially fixing the locking element.

26. The actuation device as claimed in claim 23, wherein the coupling device comprises at least one slide pin which is arranged on the rocker arm shaft, or a slide rail which is arranged on the rocker arm shaft, and on which the bearing block is arranged so as to be displaceable radially relative to the rocker arm shaft.

27. The actuation device as claimed in claim 23, wherein the coupling device comprises a clamping device, by means of which the bearing block can be clamped in the radial direction against the first and second cutouts.

28. The actuation device as claimed in claim 16, wherein an electromagnetic and/or pneumatic and/or hydraulic switch device, by means of which the locking element can be actuated so as to be brought optionally into and out of engagement with the first and second cutouts.

29. The actuation device as claimed in claim 16, wherein the poppet valve is a gas exchange valve.

30. An internal combustion engine comprising a poppet valve with a switchable actuation device as claimed in claim 16.

31. The internal combustion engine of claim 30, wherein the internal combustion engine is a diesel internal combustion engine.

32. A motor vehicle comprising an internal combustion engine as claimed in claim 30.

33. The motor vehicle of claim 32, wherein the motor vehicle is a utility vehicle.

Description

[0024] The aspects and features of the invention described above may be combined with each other in arbitrary fashion. Further details and advantages of the invention are described below with reference to the appended drawings. The drawings show:

[0025] FIG. 1: a diagrammatic depiction of a switchable actuation device for a poppet valve in an internal combustion engine according to an embodiment of the invention;

[0026] FIG. 2: an exploded diagrammatic depiction of a two-piece rocker arm of the switchable actuation device according to an embodiment of the invention;

[0027] FIG. 3: an exploded diagrammatic depiction of a coupling device of the switchable actuation device according to an embodiment of the invention;

[0028] FIG. 4: a diagrammatic side view of the switchable actuation device according to FIG. 1 in a locking position S.sub.a and a release position S.sub.e;

[0029] FIG. 5: an enlarged detail view of FIG. 4 to illustrate the slope angle of the groove flanks; and

[0030] FIG. 6: a motor vehicle comprising an internal combustion engine with a switchable actuation device according to an embodiment of the invention.

[0031] The same or functionally equivalent elements are designated with the same reference signs in all figures and in some cases are not described separately.

[0032] FIG. 1 shows a diagrammatic depiction of a switchable actuation device 100 for a poppet valve in an internal combustion engine 20 according to an embodiment of the invention. The actuation device 100 here comprises a two-piece rocker arm 10 for actuating the poppet valve (not shown in detail). The two-piece rocker arm 10 for this has a first rocker arm portion 1a which is mounted pivotably about a rocker arm shaft 2, i.e. rotatably through a specific angular range about the rocker arm shaft 2. A preferably hollow cylindrical bearing sleeve 1a1 is attached to this first rocker arm portion 1a concentrically with the rocker arm shaft 2, and in turn a second lever arm portion 1b is mounted pivotably thereon. In the mounted state shown in FIG. 1, the bearing sleeve 1a1 is not however visible (see FIG. 2), so here the two rocker arm portions 1a and 1b appear to be mounted next to each other on the rocker arm shaft 2. The feature used in this context, that the bearing sleeve 1a1 is attached “concentrically” with the rocker arm shaft 2, here means that the bearing shaft 1a1 and the rocker arm shaft 2 are arranged about a common center axis (dotted line in FIG. 1) such that the first rocker arm portion 1a and the second rocker arm portion 1b mounted on the bearing sleeve 1a1 are pivotable about this common center axis. In other words, the term “concentric” in this context may also mean “coaxial”. Concentric here does not however mean that the bearing sleeve 1a1 necessarily completely surrounds the rocker arm shaft 2, but this is however possible.

[0033] The first rocker arm portion 1a may here, as shown, be actively connected to a cam 11 of the camshaft 12 via a roller 1a3 which is rotatably mounted on the first rocker arm portion 1a. In other words, the first rocker arm portion 1a may be set in motion, in particular in a pivot movement about the rocker arm shaft 2, by a periodic movement of the cam 11 during rotation of the camshaft 12. This movement of the first rocker arm portion 1a may or may not be optionally transmitted to the second rocker arm portion 1b by means of a coupling device 4 (described in more detail below). For this, the coupling device 4 is configured to optionally connect the two rocker arm portions 1a, 1b releasably together in a rotationally fixed fashion. In other words, the first and second rocker arm portions 1a and 1b may be coupled together by means of the coupling device 4 for motion transmission. The second rocker arm portion 1b may here be actively connected to the poppet valve, preferably a gas exchange valve, so that in the coupled state of the two rocker arm portions 1a, 1b, the poppet valve can be moved indirectly and periodically by means of a cam 11 of the camshaft 12 between a closed and an open position. The above-mentioned assignment of the first or second rocker arm portion 1a, 1b to a cam 11 or a valve may however also be reversed.

[0034] FIG. 1 furthermore shows that the rocker arm shaft 2 in the present case is not designed as a continuous cylinder but has flattened regions 2a which serve for fixing a coupling device 4 for releasable, rotationally fixed connection of the first and second rocker arm portions 1a, 1b.

[0035] Here, the coupling device 4 is configured as a bearing block 4b which is guided on two guide pins 4d1, 4d2 and clamped against the first and second rocker arm portions 1a, 1b by means of a clamping device 4e in the form of two coil springs 4e1, 4e2. In the present embodiment, the coupling device 4 is here arranged above the rocker arm shaft 2 in the gravitational direction. Alternatively however, other positions of the coupling device 4 relative to the rocker arm shaft 2 are possible. This, the precise configuration of the bearing block 4b and the function of the coupling mechanism according to the invention are described in more detail in connection with the following figures.

[0036] FIG. 2 shows a diagrammatic, exploded depiction of a two-piece rocker arm 10 of the switchable actuation device 100 according to an embodiment of the invention. As mentioned above, the two-piece rocker arm 10 here has a first rocker arm portion 1a and a second rocker arm portion 1b. The two rocker arm portions 1a and 1b may here each be configured as a one-sided lever, i.e. one end region of each may be designed for pivotable mounting of the lever and another end region of each for force transmission. As shown in FIG. 2, a bearing sleeve 1a1—in the present case, in the form of a hollow cylinder—is attached to the first rocker arm portion 1a. If the bearing sleeve 1a1 and the first rocker arm portion 1a are here made from several pieces, the fixings—i.e. the preferably permanent, rotationally fixed interconnection—may be achieved for example by welding, soldering and/or press fitting. Alternatively, the bearing sleeve 1a1 and the first rocker arm portion 1a may also be formed as one piece, e.g. the bearing sleeve 1a1 is formed integrally on the first rocker arm portion 1a.

[0037] The second rocker arm portion 1b is pivotably mounted on the hollow cylindrical bearing sleeve 1a1. In other words, the bearing sleeve 1a1 attached to the first rocker arm portion 1a may thus serve as a plain bearing for the second rocker arm portion 1b. In order to fix the axial position of the second rocker arm portion 1b on the bearing sleeve 1a1, the bearing sleeve 1a1 may furthermore comprise a groove 1a2 running circumferentially, i.e. perpendicularly to the rocker arm shaft 2. A locking ring 5 may be inserted therein for securing the axial position of the second rocker arm portion 1b, wherein to reduce friction, also a thrust washer 6 may be arranged axially between the second rocker arm portion 1b and the locking ring 5. To reduce friction further, the two-piece rocker arm 10 may furthermore comprise a preferably hollow cylindrical plain bearing bush 7, by means of which the first rocker arm portion 1a and/or the bearing bush 1a1 are/is mounted on the rocker arm shaft 2. Preferably, the plain bearing bush 7 is here configured to surround the rocker arm shaft 2 concentrically, or to completely enclose this circumferentially. Instead of using a (optional) plain bearing bush 7, the first rocker arm portion 1a and/or the bearing bush 1a1 may also be mounted directly on the rocker arm shaft 2, wherein then preferably additionally a slip layer, e.g. MoS.sub.2, may be applied to the rocker arm shaft 2.

[0038] For releasable, rotationally fixed connection of the first and second rocker arm portions 1a and 1b, the first rocker arm portion 1a comprises a first cutout 3a and the second rocker arm portion 1b comprises a second cutout 3b. In the present case, these take the form of a respective groove extending parallel to the rocker arm shaft 2 with trapezoid cross-section. The two cutouts 3a and 3b are arranged and dimensioned such that, as a whole, they may supplement each other to form a complete groove in which a locking element 4a (described in more detail below and preferably of complementary shape) may engage or be inserted in order to lock or couple the two rocker arm portions 1a and 1b. If this locking element 4a is in engagement with the first and second cutouts 3a, 3b (=locking position S.sub.a), the two rocker arm portions 1a and 1b are connected rotationally fixedly by the locking element 4a which bridges the two cutouts 3a, 3b, so that movement can be transmitted between the camshaft 12 and the poppet valve. If however the locking element 4a is not in engagement with the first and second cutouts 3a, 4b (=release position S.sub.e), the two rocker arm portions 1a and 1b are not coupled together for motion transmission, i.e. they are pivotable independently of each other, so that in this case no movement can be transmitted between the camshaft 12 and the poppet valve. In the present case, the locking element 4a engages in the first and second cutouts 3a, 3b “from above”. Alternatively, by corresponding arrangement of the first and second cutouts 3a, 3b and the coupling device 4, an engagement “from below” or from any radial direction may be achieved.

[0039] FIG. 3 shows an exploded diagrammatic depiction of a coupling device 4 of the switchable actuation device 100 including a locking element 4a, in the present case formed as an insert wedge, according to one embodiment of the invention. The locking element 4a, which has its greatest extent along the rocker arm shaft 2, is formed complementary in shape to the first and second cutouts 3a, 3b (see FIG. 2). In this way, the locking element 4a may cooperate as optimally as possible with the first and second cutouts 3a, 3b in the form of a tongue-and-groove engagement, in order to releasably connect the two rocker arm portions 1a and 1b together rotationally fixedly.

[0040] To hold and guide the locking element 4a and in particular to switch between the locking position S.sub.a and the release position S.sub.e as reliably as possible, two pegs 4a1 and 4a2 are attached to the locking element 4a, by means of which the locking element 4a is mounted pivotably in a bearing block 4b. The bearing block 4b is here configured as a portal shape and comprises two bearing cheeks 4b1, 4b2 which are spaced apart in the axial direction and each comprise slots 4b3 (only one being shown) extending in the circumferential direction, in which the locking element 4a is guided by means of the pegs 4a1, 4a2. This slot guidance allows a restricted movement of the locking element 4a in the circumferential direction, which facilitates the insertion of the locking element 4a in the first and second cutouts 3a, 3b and hence the change between the locking position S.sub.a and the release position S.sub.e. In order to additionally fix the locking element 4a in the radial direction, the bearing block 4b furthermore comprises a guide roller 4c mounted rotatably in the axial direction and resting on the locking element 4a. Preferably, the rotatably mounted guide roller 4c may here roll on an outer face of the locking element 4a, whereby advantageously an optimal radial force transmission for securing the locking element 4a can be achieved at any time or in any pivot position.

[0041] Furthermore, the present embodiment of the bearing block 4b comprises two guide eyes 4f1 and 4f2, by means of which the bearing block 4b is guided, preferably for movement in the radial direction, on two slide pins 4d1 and 4d2 (see FIG. 1). It is particularly advantageous here if the coupling device furthermore comprises a clamping device, by means of which the bearing block 4b can be clamped in the radial direction against the first and second cutouts 3a, 3b. As shown in FIG. 1, this may take the form of two coil springs 4e1, 4e2 surrounding the slide pins 4d1, 4s2, wherein the coil springs 4e1, 4e2 each rest with one end on the respective guide eye 4f1, 4f2 and with the opposite end on a stop of the respective slide pin 4d1, 4d2.

[0042] FIG. 4 shows a diagrammatic side view of the switchable actuation device 100 according to FIG. 1, respectively in a locking position S.sub.a (top) and in a release position S.sub.e (bottom). Here, in the locking position S.sub.a shown at the top, the locking element 4a is almost completely inserted in the first and second cutouts 3a, 3b, whereby the first and second rocker arm portions 1a and 1b are coupled together for motion transmission. In the release position S.sub.e shown at the bottom, the locking element 4a is not in contact with the first and/or second cutout 3a, 3b, whereby the first and second rocker arm portions 1a, 1b are movable independently of each other. The change between these two positions takes place by movement of the locking element 4a in a plane perpendicular to the rocker arm shaft 2, preferably by radial movement of the locking element 4a. In the embodiment shown here, for this the bearing block 4b guided on the slide pins 4d1, 4d2 may be raised or lowered radially relative to the rocker arm shaft 2 by means of the switch device 13. The switch device 13 is here designed in the form of an electromagnet which cooperates magnetically with a permanent magnet material attached to the bearing block 4b. Also or alternatively, the switch device 13 may also comprise a piston-cylinder arrangement attached to the bearing block 4b, wherein the cylinder is loaded with a hydraulic medium and/or compressed air for switching the locking element 4a.

[0043] FIG. 5 shows an enlarged detail view of the region of the first cutout 3a in the release position S.sub.e shown in FIG. 4. Here, the shape or cross-section of the cutout 3a and the locking element 4a can be seen more clearly. In the present case, the first and second cutouts 3a, 3b are each formed as a trapezoid groove extending parallel to the rocker arm shaft 2. In other words, the first and second cutouts 3a, 3b have a groove cross-section which tapers towards the rocker arm shaft 2. This is delimited towards the rocker arm shaft 2 by a groove base and at the side by two groove flanks, wherein these are sloped by a slope angle α in comparison with an ideal rectangular cross-section. This slope facilitates insertion of the complementarily shaped locking element 4a in the first and second cutouts 3a, 3b. Here, the slope angle α of the groove flanks is however smaller than the self-locking angle α.sub.h of the corresponding material pairing of the first lever arm portion and locking element, and/or of the second lever arm portion and locking element (11.4° in this example), so that the locking element 4a is clamped in self-locking fashion in the locking position S.sub.a. In this way, advantageously, a reliable fixing of the locking element 4a in the circumferential direction may be achieved.

[0044] FIG. 6 shows a motor vehicle 30 comprising an internal combustion engine 20 with a switchable actuation device 100 for a poppet valve according to one embodiment of the invention. In the present case, the motor vehicle 30 is a utility vehicle in the form of a truck. Alternatively however, the motor vehicle 30 may also be a bus and/or a semitrailer. Advantageously, by means of the switchable actuation device 100 according to the invention in the motor vehicle 30 depicted diagrammatically, a gas exchange of individual poppet valves of the internal combustion engine 20 may be deactivated in targeted fashion—preferably in low load operation—and thereby as a whole the fuel consumption may be lowered.

[0045] Although the invention has been described with reference to specific exemplary embodiments, it is evident to the person skilled in the art that various changes may be made and equivalents used as substitutes without leaving the scope of the invention. Accordingly, the invention is not restricted by the exemplary embodiments disclosed but comprises all exemplary embodiments which fall within the scope of the appended patent claims. In particular, the invention also claims protection for the subject and features of the subclaims independently of the claims to which reference is made.

LIST OF REFERENCE SIGNS

[0046] 1a First rocker arm portion

[0047] 1a1 Bearing sleeve

[0048] 1a2 Groove

[0049] 1a3 Roller

[0050] 1b Second rocker arm portion

[0051] 2 Rocker arm shaft

[0052] 2a Flattened portion of rocker arm shaft

[0053] 3a First cutout

[0054] 3b Second cutout

[0055] 4 Coupling device

[0056] 4a Locking element

[0057] 4a1, 4a2 Pegs

[0058] 4b Bearing block

[0059] 4b1, 4b2 Bearing cheeks

[0060] 4b3 Slot

[0061] 4c Guide roller

[0062] 4d1, 4d2 Slide pin

[0063] 4e Clamping device

[0064] 4e1, 4e2 Coil springs

[0065] 4f1, 4f2 Guide eyes

[0066] 5 Locking ring

[0067] 6 Thrust washer

[0068] 7 Plain bearing bush

[0069] 10 Two-piece rocker arm

[0070] 11 Cam

[0071] 12 Camshaft

[0072] 13 Switch device

[0073] 20 Internal combustion engine

[0074] 30 Motor vehicle

[0075] 100 Actuation device

[0076] S.sub.a Locking position

[0077] S.sub.e Release position

[0078] α Slope angle

[0079] α.sub.h Self-locking angle