PH12015501984B1 - Variable valve train for actuating a valve of an internal combustion engine - Google Patents

Abstract

A variable valve train (2) for actuating a valve (70) of an internal combustion engine, comprises an actuation system for periodically opening and closing the valve (70); and a control system (90, 100). The control system comprises a gas position operating element (92, 102), whose position is variable in dependence on a gas command; a movable adjustment element (95, 105), which is so coupled to the support body (80) that by movement of the adjustment element the position of the first rotational axis (14) is changed and thereby the valve lift is adjusted; and a force-fit element (94, 104) connecting the gas position operating element (92, 102)in a force-fit manner to the adjustment element (95, 105).

Description

According to a further aspect, the valvetrain and/or the control system further comprises a worm gear 84c for driving the pivoting drive gearwheel 84b, the worm gear being in meshing connection with the pivoting drive gearwheel 84b.

According to a further aspect, the connecting rod 30 and the guiding member 60 are members of a pinned, planar linkage.

According to a further aspect, the valve 70 is an intake valve, and the second driving member also actuates an exhaust valve 78.

According to a further aspect, a maximum lift height of the valve 70 is at least 5 mm.

It is a general aspect of the invention that the valvetrain 2 comprises a planar linkage with four links, and/or a pinned linkage of four links. Herein, the joints preferably comprise the driving axis 24, the guiding axis 66, the first connecting rod joint 34 and the second connecting rod joint 36. All elements of the linkage described herein are connected to each other in a form-fit manner.

It is a general aspect of the invention that the valvetrain 2 is provided in a cylinder head portion of the combustion engine, as is exemplified in Fig. 1. An arrangement in the cylinder head portion is to be understood as follows: The valve crank 16 is generally (i.e., in at least one possible position of the rotational axis 14 and/or in at least one pivotal position of a pivoting frame 80, as shown for example in Fig. 3), mounted on a cylinder head side relative to a dividing surface between the motor block and the cylinder head.

Even if a cylinder head and a motor block are not clearly distinguishable from one another in the combustion engine, such a dividing surface can be defined, for example, by a surface defined by the piston head, wherein the piston is in the top dead center position. According to this characterization, the valvetrain 2 corresponds to an overhead camshaft valvetrain, wherein the valve crank 16 corresponds to the camshaft.

By this arrangement, an encapsulated setup of the valvetrain is enabled, in which the parts of the valvetrain are arranged within an encapsulation.

According to an aspect, the valvetrain 2 can be subdivided into an active subsystem and a passive subsystem. The active subsystem can be characterized as follows: The motional state of the active subsystem is substantially determined by the motional state of the valve crank 16 (i.e., by a rotational angle of the valve crank 16 and by the position of the valve crank axis 14), and/or the active subsystem is connected to the valve crank 16 in a form-fit manner. The passive subsystem is connected to the active subsystem in a force- fit manner, in particular by means of the valve spring 72.

For more details regarding Figs. 1-3 we refer to DE'127, the entire content of which is hereby incorporated by reference into the present specification. In particular, paragraphs

[0144] - [0159] are referred to, as well as the other passages of DE'127 referenced therein, which are hereby incorporated by reference. In particular, all aspects of a valvetrain or engine described in DE'127, insofar as these are additionally equipped with the control system described herein, are considered as belonging to the present invention.

Hereinafter, a valvetrain is described according to a further embodiment of the invention with reference to Figs. 4-5. Therein, corresponding parts are given the same reference numerals as in Figs. 1-3, although some geometrical details may be changed. The description of Figs. 1-3, and the description given in DE'127, also apply to this embodiment, as far as not shown differently in the figures or hereinafter. This is especially true for the actuation system.

Instead of the pivoting drive 84 or 84a-84d shown in Figs. 1-3 (and its actuator) for pivoting the pivot frame (support body) 80, the valvetrain shown in Figs. 4-5 includes a control system 90 described below.

This control system 90 includes a control cable 92a, which is guided in a guide sleeve 91 displaceably along a longitudinal direction (along the axis 96 of the guide sleeve 91). The control cable 92a is mechanically coupled to a gas control device (e.g., a gas pedal or handle), so that the position of the control cable 92a is changed together with the cable receiving part 92 described below, in response to a gas command given to the gas control device.

The control cable 92a is further coupled to a cable receiving part (gas position operating element) 92, which is designed as a plug arranged to be longitudinally displaceable in the guide sleeve 91. Specifically, the free end of the control cable 92a is hooked by a thickened portion into the cable receiving part 92 in such a manner that a pull of the control cable (to the right in Fig. 5) is transferred to the cable receiving part 92. Once the pull on the control cable 92a decreases again, the cable receiving part 92 returns toward its idle position (to the left in Fig. 5) via a return spring 96 described in more detail

Co below. Thus, an operation (pull or release) of the control cable 92a results in a longitudinal displacement of the control cable 92a together with the cable receiving part 92.

Left of the cable receiving part 92, Fig. 5 further shows a stopper screw (more generally, astopper element for the gas position operating element 92), which limits a movement of the cable receiving part 92 to the left (toward reduced lift height). The stop is adjustable: in this example, by turning the stopper screw. This stop prevents that the movement is limited by stops in other, more mechanically stressed and / or less stable subsystems, and thus contributes to the protection of the mechanical system.

The cable receiving part 92 is connected via an intermediate spring 94 to a follower 95 in a force fit manner. The intermediate spring 94 pushes the follower 95 against a stop 92b of the cable receiving part 92. The follower 95 is also mounted longitudinally displaceably, namely is guided longitudinally displaceably in an adjustment rail 91b of the guide sleeve 91. By the force fit coupling, the follower 95 follows the movement of the cable receiving part 92, with an adjustable delay through the hardness of the intermediate spring 94, as far as the boundary conditions for the movement of the follower 95 permit.

The follower 95 is further positively coupled via a slotted guide 85 to the support body (pivoting frame) 80. Specifically, the follower 95 comprises a slotted element with a control slot 85b which is inclined relative to the longitudinal direction. A control cam 85a connected to a pivot frame 80 is engaged in the control slot 85b.

The control slot in Fig. 4 is designed as a straight slot. In Fig. 5 a variant is shown in which the control slot is curved such that the transmission ratio between the follower 95 and the support body 80 is not constant. In particular, the transmission ratio decreases for larger valve lift (maximum lift height), so that a given movement of the follower 95 is associated with less movement of the support body 80.

The coupling of the follower 95 to the support body 80 is such that the support body 80 is pivoted about the axis 24 by a movement of the follower 95. Thereby, the position of the first rotation axis 14 is changed, and thus the valve lift is adjusted.

Therefore, the follower 95 is also referred to as adjustment element. More generally, herein an adjustment element is referred to as a jointly movable drive component for the pivoting frame 80 from the intermediate spring 94 (the latter not included). Individual parts of the adjustment element do not need to be positively connected to each other, so long as they are moved together. A gas position operating element is defined as a jointly movable drive component up to the intermediate spring 94 (the latter not included). This includes, in the present case, at least the cable receiving part 92 and optionally the control cable 92a.

The return spring 96 is coupled to the cable receiving part 92 indirectly via the follower 95. The return spring 96 urges the follower 95 in Fig. 5 to the left, i.e., in a direction reducing the lift height of the valve. If the control cable 92a is thus released (movement relative to the guide sleeve 91 in the release direction - to the left - is released), then the bias applied by the return spring 96 and the intermediate spring 94 on the cable receiving part 92 relative to the guide sleeve 91 causes the cable receiving part 92 and the control cable 92a to actually move in the release direction.

On the follower 95, a maximum stopper element 124 and a minimum stopper element 126 are further fixedly attached, as shown in Fig. 4, and jointly movable together with it. Together with a stopper pin 122 which is not moved with the follower 95, these stopper elements 124 and 126 respectively define a maximum or a minimum stop, which restricts the movement (range for longitudinal movement) of the follower 95. Consequently, possible ranges for the position of the first rotational axis 14 and thus for the valve lift can be restricted.

Herein, the maximum stop (the stop that is produced by the interaction of the maximum- stopper element 124 with the stopper pin 122) restricts a movement of the adjustment element 95 in a direction increasing the lift height of the valve (to the right in Fig. 4). Thus, the maximum-stop limits a maximum lift height of the valve lift.

Correspondingly, the minimal stop (the stop that is produced by the interaction of the minimum-stopper element 126 with the stopper pin 122) limits a movement of the adjustment element 95 in a direction reducing the lift height of the valve lift (to the left in

Fig. 4). Thus, the minimum-stop limits a minimal lift height of the valve lift.

The position of the stopper pin 122 is adjustable by a positioning actuator 122a, whereby the stopper pin 122 is pro- and retracted by the positioning actuator 122a. By adjusting the position of the stopper pin 122, the maximum-stop and/or the position of the adjustment element 95 at the maximum stop is changed. Thus, the maximum lift height is adjustable by adjusting the position of the stopper pin 122. The same is true for the minimum-stop and/or the minimum lift height. By appropriate contouring of abutment surfaces of the stopper elements 124, 126 and the stopper pin 122 and by proper alignment of the stopper pin 122, for any position of the stopper pin 122 any desired maximum and minimum values for the lift height of the valve lift can be set.

The positioning actuator 122a can be controlled, e.g., in response to an engine speed of the internal combustion engine (and optionally in response to additional parameters). Thus, the maximum-stop may allow excluding unfavorable gas commands, such as gas commands increasing the valve lift too abruptly. Also, the minimum stop may allow defining an idle valve lift which is appropriate for the respective engine speed (and / or for other parameters).

The control of the positioning actuator 122a is performed according to a general aspect such that a position of the stopper pin 122 is controlled in dependence on the engine speed. This control can be set so that a first position is set for engine speeds below a predetermined limit speed, and that a second position is set for speeds above the limit speed. However, in general, the control is executed continuously so that for the respective engine speed (and optionally other parameters) appropriate maximum and minimum values for the lift height of the valve lift are specified.

Additionally, fixed stops for a movement of the follower 95 may be provided that define, regardless of the positioning actuator 122a, an absolute minimum and/or maximum position of the follower 95, which the follower 95 may not exceed in any circumstances.

Because the adjustment element 95 is connected only indirectly to the control cable 92 via the intermediate spring 94, these restrictions are not noticeable as hard stops at the gas position operating element; rather, they manifest themselves in a gradual increase in counter force by which the intermediate spring 94 counteracts the operation and signals to the user a soft boundary. Then, once a valve lift range is made available by movement of the stopper pin 122 (e.g., because the engine speed has increased enough), it is then taken without the operator having to change the position of the gas position operating element.

In the following, with reference to Figs. 6a, 6b and 7, a valvetrain in accordance with a further embodiment of the invention is described. Therein, corresponding parts are given the same reference numerals as in Figs. 1-5, and the description of Figs. 1-5 also applies to this embodiment, insofar as not described differently in the following or shown differently in the figures. Compared to Figs. 4 and 5, only the control system is changed, so that in the following only this is described.

The control system 100 of Figs. 6a-7 includes a cable receiving part 102 (gas position operating element) which is rotatably mounted about an axis 86 on a stationary shaft 101 (possibly indirectly via further intermediate parts, such as the follower 103 described below). A control cable (not shown) is mechanically connected at one end to the cable receiving part 102, and at another end to a gas control device (e.g. gas pedal or handle), so that the position (angle of rotation) of the cable receiving part 102 changes in response to a gas command given to the gas control device.

Once the pull on the cable 102a decreases again, the cable receiving part 102 is released towards its idle position (towards reduced lift height) by return spring 106 described in further detail below. In addition, a return cable attached to the cable receiving part 102 in the opposite direction may return the cable receiving part 102. Thus an operation (pull or release) of the control cable results in a corresponding rotation of the cable receiving part 102.

The cable receiving part 102 is connected via an intermediate spring 104 to an adjustment element 105 in a force-fit manner. The adjustment element 105 includes a follower 103, a transmission body 110, and an adjustment shaft 105a with adjustment crank 105b, as well as other components such as intermediate springs as described below. The follower 103, the transmission body 110 and the adjustment shaft 105 are rotatably mounted about the adjustment axis 86 to the shaft 101. The intermediate spring 104 exerts a torque on the follower 103 such that the follower 103 is pressed to a stopper (not shown) of the cable receiving part 102, which limits the rotation of the follower 103 relative to a rotation of the cable receiving part 102 in one rotational direction (direction toward larger valve lift). Due to the force-fit coupling, the follower 103 follows the rotary movement of the cable receiving part 102 with a delay that is adjustable by the hardness of the intermediate spring 104, as far as the boundary conditions for the rotational movement of the follower 103 permit such movement.

The follower 103 further includes a stop 103d (see Fig. 7), which cooperates with a further stop 105d of the adjustment element 105 to transmit a rotation of the follower 103 (in the direction towards a larger valve lift, i.e., upon a gas increase command) to the adjustment shaft 105a. A return spring 106 couples a rotation in the opposite direction (during gas removal command) between the adjustment shaft 105a and follower 103 due to being pre-biased towards an abutment of the stops 103d, 105d against each other.

In the embodiment described here, the further stop 105d, as well as an end of the return spring 106, is fixated on the transmission body 110. The transmission body 110 is connected to the adjustment shaft 105a in a form-fit manner with respect to rotations, and therefore transmits any rotation to the or from the adjustment shaft 105a. Alternatively, the additional stop 105d and / or an end of the return spring 106 may be mounted directly to the adjustment shaft 105a or to any other part that is rotatable together with the adjustment shaft 105a. In each of these cases, the follower 103 is coupled via the adjustment shaft 105a and a crank joint 105b, 87 to the support body (pivoting frame) 80. Namely, an adjustment crank 105b of the crank joint is rotatable together with the adjustment shaft 105a and transmits a rotary movement of the adjustment shaft 105a into a movement of the support body: The support body 80 is pivoted about the axis 24, and thereby the position of the first rotation axis 14 is changed, and thus the valve lift adjusted. The coupling between the adjustment shaft 105a and support body 80 is by positive fit (form fit).

The crank joint 105b, 87 is dimensioned in such a way, and/or the adjustment crank 105b is located in such a way, that the transmission ratio between the follower 103 and the support body 80 is non-constant and, in particular, that the transmission ratio diminishes with growing valve lift (maximum lift height), so that a given rotational movement of the follower 103 is associated with a reduced movement of the support body 80.

The return spring 106 is coupled to the cable receiving part 102 indirectly via the follower 103. The return spring 106 biases the follower 103 in a direction reducing the lift height of the valve. Thus, when the cable 102 yields, the bias force exerted by the return spring 106 and the intermediate spring 104 to bias the cable receiving part 102 causes the cable receiving part 102 to be actually rotated in the release direction.

The control system 100 further includes an anti-reverse mechanism 112 for the adjustment element 105. The anti-reverse mechanism 112 comprises an anti-reverse 14

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EEE eee rrr ——— element 112a that is jointly rotatable with the adjustment element 105 (i.e. forcibly entrained with the adjustment element 105 with respect to rotation) and a counter element 112b that is (with respect to rotation) stationary (e.g., fixedly mounted on the cylinder head). The anti-reverse element 112a is attached to the transmission body 110.

In alternative embodiments, it can also be attached to any other part that is co-rotatable with the adjustment shaft 105a.

In an engaged condition, the anti-reverse element 112a is axially coupled (pressed) by means of an axial spring 114 acting on the transmission body 110 to the stationary counter element 112b. The surfaces of the elements 112a, 112b contacting each other have a saw-tooth or ratchet shape, respectively, by which are defined a freewheeling direction and a locking direction for the movement (rotation) of the adjustment element 105. The locking direction is directed such that a movement of the adjustment element 105 in a direction reducing the lift height of the valves is locked. The locking direction can alternatively also be defined as follows: The locking direction is directed against a pressing direction, in which a spring force of the valve spring presses the adjustment element.

Thereby, the anti-reverse mechanism ensures that the spring force of the valve spring is absorbed, at least in the engaged state of the anti-reverse mechanism, by a stationary component such as the cylinder head.

The anti-reverse mechanism is releaseable, i.e., the engaged state can be supplanted by a non-engaged state in which the anti-reverse mechanism allows freewheeling of the adjustment element 105 in both directions. In the embodiment described herein, the non- engaged state is achieved by the anti-reverse element 112a being moved in the axial direction away from the counter-element 112b against the spring force of the axial spring 114.

For this purpose, the control system 100 includes a release mechanism for releasing the anti-reverse mechanism, which is described in the following with reference to Fig. 7. The release mechanism comprises a first contour surface 116a attached to the anti-reverse element 112a, and a follower contour surface 116b attached to the follower 103. The contour surfaces are formed such that upon rotation of the follower 103 in a valve lift- reducing direction, the anti-reverse element 112a is moved away from the counter- element 112b in the axial direction against the spring force of the axial spring 114 and thereby the non-engaging state is achieved. Thereby, the anti-reverse mechanism is released upon gas removal command, so that a reduction of the valve lift is possible. The release is effected by moving the anti-reverse element 112a away from the counter element 112b by a mechanical abutment of the contour surfaces 116a, 116b. Therefore, a reliable releasing is ensured at any time.

Further, as shown in Figs. 6a and 7, a maximum stopper element 124 and a minimum stopper element 126 are fixed to the follower 103 so that they are rotatable together with the follower. In combination with a stopper pin 122 which is not jointly movable with the follower 103, these stopper elements 124 and 126 provide a maximum stop and a minimum stop, respectively, which restrict the movement (range available for rotary motion) of the follower 103. These stops function in an analogous manner as described above with respect to Figs. 4-5, and can be adjusted in a similar manner by the positioning actuator 122a.

Different from Figs. 4-5, the stopper elements 124 and 126 shown in Fig. 6a are arranged such as to abut, respectively, with a (in the extending direction) front-side surface and with a rear-side shoulder surface of the stopper pin 122 thereby providing the maximum stop and the minimum stop, respectively.

Further, the minimum stopper element 126 is rigid in rotation direction, but adapted to be flexible in the axial direction. Further, the front side (in the extension direction) surface of the stopper pin 122 is curved or tilted in such a manner that the minimum stopper element 126, when located on the front side of the stopper pin 122, can be rotated rearwards (i.e., in Fig. 6 to the left) past the front surface by being pressed in axial direction. Conversely, the shoulder surface of the stopper pin 122 is shaped such that a reverse movement (rotation frontwards past the shoulder surface, i.e., in Fig. 6 to the right) is prevented by the abutment between the minimum stopper element 126 and rear shoulder surface of the stopper pin 122, because pressing of the minimum stopper element 126 in the axial direction is avoided. In this way it is ensured that, on the one hand, the minimum stopper element 126, when it has gotten into a non-appropriate location in front of to the stopper pin 122 (in Fig. 6a right), can return to its appropriate location again, and that, on the other hand, the minimum stopper element 126 reliably fulfills its function to produce a minimum-stop.

Like in Fig. 4, also in the embodiment of Figs. 6a-7 the maximum and the minimum stop are adjustable by the positioning actuator 122a, wherein the positioning actuator 122a is controllable, e.g., in dependence of an engine speed of the internal combustion engine and / or other parameters. Thereby, in particular, by changing the minimum stop it is possible to enable a control of the idle-state valve lift which is adapted to the respective conditions.

Fig. 6a further shows a second minimum stopper element 126'. Also, the second minimum stopper element 126' is connected to the follower 103 in a manner such that it can be jointly rotated with the follower. The minimum stopper element 126' interacts with a second stopper counter-element 122' which is connected to the cylinder head (more specifically, to the counter-element 112b) to produce a further minimum stop. The stopper counter-element 122' includes an adjustment element (adjustment screw), which can be retracted and extended (screwed) to change the position of the further minimum stop.

Thus, the minimum stopper element 126 provides a variably controllable first minimum stop, and the minimum stopper element 126° provides a fixedly assignable second minimum stop, below which it is impossible to fall under any circumstances regardless of the positioning actuator 122a. In a variation of the embodiment, one of the two minimum stops can also be omitted.

The second minimum stopper element 126' illustrates some general aspects. According to one aspect, a stopper element is not necessarily fixed onto the follower 95/105, but it only needs to be coupled to the follower in such a way that it moves jointly with it in a defined manner. Accordingly, in this example the minimum stopper element 126' is fixed to the anti-reverse element 112a. Since the anti-reverse element 112a is always jointly rotated with the follower 103 (even if both elements can be shifted with respect to each other in the axial direction), a stop for the follower 103 is thereby provided as well.

According to a further aspect, the actuator 122a may also be replaced by a rigid connection, or by a preadjustable but otherwise rigid connection to a stationary element.

Figures 8a-9b show a control system 100 of a valvetrain in accordance with a further embodiment of the invention. Therein, corresponding parts are assigned the same reference numerals as in Figs. 1-7, and the description of Figs. 1-7 also applies to this embodiment accordingly, unless shown differently in the figures or in the following description.

Compared to the embodiment shown in Figs. 6a-7, mainly the anti-reverse mechanism 112 is changed, so that in the following, only the anti-reverse mechanism is described.

The anti-reverse mechanism 112 includes a one-way clutch 113b which cooperates with the adjustment element 105 (more precisely, with the adjustment shaft 105a) in such a way that a freewheeling direction and a locking direction for the movement (rotation) of the adjustment shaft 105a are defined in an analogous manner as described above: When the reverse-blocking body 113a is locked stationarily, the adjustment shaft 105a is rotatable only in the freewheeling direction, but not in the blocking direction (direction decreasing the lift height of the valves). To this end, the one-way clutch couples the adjustment shaft 105a to a reverse-blocking body 113a which can be locked (in terms of rotation).

The one-way clutch 113b is configured according to the illustrated embodiment as a sleeve clutch (sleeve coupling). The sleeve clutch 113b is disposed around a portion (anti-reverse element 112a) of the adjustment shaft 105a of the adjustment element 105, and thus couples the adjustment element 105 to the reverse-blocking body 113a.

The freewheeling and blocking directions of the adjustment shaft 105a have the same effect as described for Figs. 6a-7: The blocking direction is directed such that movement of the adjustment element 105 is locked in a direction decreasing the lift height of the valves. In Fig. 9, the freewheeling direction of the adjustment shaft 105a is directed in the anti-clockwise direction and the blocking direction is directed in the clockwise direction.

The locking of the reverse-blocking body 113a is performed by a locking body 112b (anti-reverse counter element) that pushes by means of a spring 115 against a locking surface 100c of the reverse-blocking body 113a, thereby keeping the locking face 100c fixed. This keeping fixed is achieved, as shown in Figs. 9a and 9b, by engagement of the locking body 112b with a profile of the locking surface 100c. The profile is such that it locks at least a rotation in the blocking direction. "Locking" is understood to include a locking of the reverse-blocking body 113a in the blocking direction, even if a rotation in the freewheeling direction is still possible, as indicated here by the sawtooth profile of the locking surface 100c.

The anti-reverse mechanism is releasable, i.e., the locking can be released so that movement of the adjustment shaft 105a is possible in both directions. The anti-reverse mechanism is adapted such that it is released during a gas removal command, so that a reduction of the valve lift becomes possible. For this purpose, the control system 100 of

Figs. 8a-9b has a release mechanism for releasing the anti-reverse mechanism 112, which is described below.

The release mechanism causes the engagement between the locking body 112b and locking surface 100c¢ to be released when the anti-reverse mechanism is released. The adjustment shaft 105a can then be rotated together with the no longer locked reverse- blocking body 113a, also in the locking direction.

The release mechanism comprises a release lever 117 having a first contour surface 117a and a follower contour surface 117b provided on the follower 103. The release lever 117 is pivotable about a lever axis 117d. The release lever 117 is arranged as a drag lever between the follower contour surface 117b and a release portion 117c of the locking body 112b.

The contour surfaces 117a and 117b are shaped in such a manner that upon rotation of the follower 103 in a valve lift reducing direction, the follower contour surface 117b lifts therelease lever 117 against the release portion 117¢ of the locking body 112b, and thus moves the locking body 112b away from the locking surface 113c against the spring force of the spring 115. Thereby, the engagement between the locking body 112b and the locking surface 113c is released, and the locking of the reverse-blocking body 113a is released.

Further alternative embodiments of the anti-reverse mechanism and the release mechanism shown in Figs. 8a-9b are conceivable. For example, the one-way clutch 113b may be configured as a releasable one-way clutch, with a release condition being satisfied when the gas command is removed. In this case, different from Figs. 8a-9b, the one-way clutch may couple the adjustment shaft 105a directly to a stationary part.

Further, different from Fig. 8a-9b, the reverse-blocking body 113a may be rigidly connected to the adjustment shaft 105a (that is, the clutch 113b is replaced by a rigid connection). In this case, the releasable one-way clutch is formed by a ratchet mechanism, which includes the locking surface (anti-reverse element) 112d formed as a sawtooth surface, and the locking body (anti-reverse counter element) 112b (see Fig. 9a).

Furthermore, the anti-reverse mechanism 112 may be coupled to any part of the adjustment mechanism 105. Thus, differently from Figs. 8a-9b, the anti-reverse mechanism 112 is not necessarily directly coupled to the adjustment shaft 105a, but it may also be coupled to the adjustment shaft 105a via a further intermediate element, preferably via an intermediate element which is form-fit with respect to rotation.

The anti-reverse mechanism 112 in Figures 8a-9b therefore operates fundamentally according to the same principle as in Figs 6a-7: The adjustment element 105 (in particular, the adjustment shaft 105a) is coupled by means of the releasable anti-reverse mechanism 112 to a (with respect to rotation) stationary member 112b, wherein a locking direction of the anti-reverse mechanism is directed to block a movement of the adjustment element in a direction decreasing the lift height. To this purpose, the anti- reverse mechanism 112 includes an anti-reverse element 112a which is co-rotatable with the adjustment shaft 105a (i.e., forcibly entrained by the adjustment shaft 105a in relation to the rotational direction), and a (with respect to rotation) stationary — e.g., fixedly mounted to the cylinder head — counter element 112b. The anti-reverse element 112a is part of the adjustment element 105, as it is co-rotatable with the adjustment element. A further common feature of both embodiments is a release mechanism 116a, 116b and 117, respectively, for releasing the anti-reverse mechanism 112 upon a gas removal command at the gas position operating element 102.

With the anti-reverse mechanisms described herein, it is ensured that at least in the engaged state of the anti-reverse mechanism, the spring force of the valve spring is received by a stationary component such as the cylinder head. Simultaneously, it is ensured that the cylinder lift can be reliably reduced upon a gas removal command.

Further details shown in Fig. 9a and 9b are a stop 102d of the cable receiving part 102 and a stop 105d of the follower. The stops 102d and 105d limit the rotation of the follower 105 relative to a rotation of the cable receiving part 102 in a rotational direction (direction towards increased valve lift).

By means of the intermediate spring 104, the follower 103 is pressed, via the stop 105d, to the stop 102d of the cable receiving part 102, and thereby the above-described force- fit coupling between the follower 103 and the cable receiving part 102 is obtained.

Further, Fig. 9b shows a housing 130 for the control mechanism 100. Also, the second stop counter-element 122' (shown here without adjustment screw) is attached to the housing.

The embodiments described here can be varied and adapted in other ways. In particular, individual aspects of each embodiment can also be used in other embodiments and / or combined with other aspects, thereby obtaining yet further embodiments. The embodiments may also be modified and varied in different ways. Some general aspects which can be combined with any embodiment or any other aspect are described below.

For example, a different force-fit element may be used in addition to or instead of the intermediate spring shown in the embodiments. According to one aspect, such a force-fit element comprises a damping element (e.g., an oil or hydraulic damping element) which may have at least a slight spring characteristic, or a combination of spring and damping. According to a preferred aspect, the force-fit element comprises at least one of an intermediate spring and a damper. Herein, an intermediate spring may be regarded as : any element having a spring characteristic (e.g., a coil spring, gas spring, torsion spring, etc.), and a damping element may be regarded as any element with a non-negligible damping characteristic. The intermediate spring and the damping element can also be implemented by a combined element (damped intermediate spring).

In one aspect, the gas position operating element (cable or other element) can be mechanically coupled to a gas control device. Particularly preferred is a coupling to a gas control devices directly (mechanically) operable by a user, such as a gas handle or a gas pedal. Alternatively, however, a coupling to a gas control device formed by an electronically controlled element is also possible. The electronic control can be effected in dependence of various relevant data, such as a displacement at a gas handle or pedal, or a gas handle position, a gas pedal position, an engine speed, a vehicle speed, data of a traction control system, an acoustic control or the like.

According to a further aspect, the adjustment element has the same degrees of freedom of movement as the gas position operating element. For example, both elements can be rotatable or longitudinally displaceable or movable in accordance with any other common movement.

According to a further aspect, the intermediate spring exerts a force or bias to the adjustment element in such a way that the adjustment element is pressed against a stop of the gas position operating element which limits the movement of the adjustment element relative to a movement of the cable receiving part 102 in a direction towards a larger valve lift.

According to a further aspect, the adjustment element is coupled in a form-fit manner to the support body. According to a further aspect, the coupling is such that a transmission ratio between the adjustment element and the support body is not constant, and in particular that the transmission ratio is reduced for increasing valve lift, so that a given movement of the adjustment element is associated with a smaller movement of the support body than at a smaller valve lift.

According to a further aspect, the return spring is coupled to the gas position operating element via the adjustment element. According to a further aspect, the return spring exerts a bias on the adjustment element in a direction decreasing the lift height of the valve.

According to a further aspect, a method for controlling the valve train according to aspects of the invention and/or of an internal combustion engine is also provided. The method comprises moving a gas position operating element according to a gas command; (at least partially) transmitting the movement of the gas position operating element by the force-fit element to the adjustment element, thereby moving the adjustment element; transmitting the movement of the adjustment element by coupling to the support body so that the position of the first rotational axis is changed, and thus the valve lift is adjusted. The method preferably operates according to any of the optional aspects described herein, e.g., preferably the actuator adapted for adjusting the position of the stopper pin is preferably controlled in response to an engine speed of the internal combustion engine.

According to a further aspect, the valve train is configured for a motorcycle engine, and/or the internal combustion engine is a motorcycle engine. According to a further aspect, a motorcycle having such a combustion engine is provided.

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VARIABLE VALVE TRAIN FOR ACTUATING A VALVE OF AN INTERNAL

COMBUSTION ENGINE CO Ay.

The present invention relates to an internal combustion engine, in particular an internal combustion engine with a valvetrain. Furthermore, the invention relates to a variable valvetrain for operating a valve of an internal combustion engine.

Variable valvetrains are known in the art. Such variable valvetrains allow to adjust (change) a valve lift, i.e. a quantity characterizing the valve lift behavior such as the lift height (maximum height of the valve opening during an engine cycle), duration and / or phase of the valve opening relative to the engine cycle. A variable valvetrain allows adjusting the lift height as a function of, for example, a number of driving parameters (e.g., rotational speed) and of a gas command (e.g., position of a gas lever or pedal).

A particularly advantageous variable valvetrain is known from DE 10 2005 057 127 Al (hereinafter DE'127), in which also other valvetrains are cited. DE'127 in particular discloses the valvetrain shown in Figs. 1-3 of the present application. Therein, a position of the valve crank axis 14 can be adjusted by pivoting a pivoting frame 80, in order to adjust the valve lift. This is done by means of the pivoting drive 84 / 84a-84d shown in

Figs. 2 and 3.

An object of the present invention is to provide a valvetrain of an internal combustion engine with at least some of the advantages of the solution shown in DE'127, which moreover has a particularly advantageous control system for adjusting the valve lift. In particular, an aim is a control contributing to a high efficiency of the internal combustion engine especially under mixed operation, i.e., with frequently alternating partial load and full load of the internal combustion engine.

The object is achieved by the valvetrain according to claim 1 and by the internal combustion engine according to claim 9. : According to one aspect of the invention, a variable valvetrain is provided for actuating a (i.e. at least one) valve of an internal combustion engine.

An actuation system of the valvetrain for periodically opening and closing the valve comprises a first drive means mounted rotatably about a first rotational axis in a support body in such a manner that a position of the first rotational axis is variable for adjusting a valve lift, e.g., the lift height, of the valve, e.g., by movement of the support body.

A control system of the valvetrain comprises a gas position operating element, whose position is variable in dependence on a gas command (and possibly of other input quantities); a movable adjustment element which is so coupled to the support body that by movement of the adjustment element the position of the first rotational axis is changed and thereby the valve lift (in particular, the lift height and/or the phase of the valve lifting behavior) is adjusted; and a force-fit element connecting the gas position operating element in a force-fit manner to the adjustment element.

Embodiments of this valvetrain, for example, may have one or more of the following advantages: Abrupt transitions from partial load to full load operation can be avoided due to the force fit element (non-positive connection element), especially under mixed operation, i.e. frequent alternation between partial load (or "partial throttle") and full load (or "full throttle") of the internal combustion engine, or under sudden accelerations. Therefore, the widespread tendency of drivers shifting immediately to "full-throttle" mode during acceleration phases is appropriately compensated for. This ensures that the driver's command is implemented whenever appropriate, but with its timing and/or intensity being adapted; this adaptability is achievable by the force fit element (such as an intermediate spring) and the adjustment element. The force-fit clement transmits a gas command indirectly to the adjustment element and/or to the * support body as follows: A movement of the gas position operating element results at first in a bias — the bias increasing with increasing movement of the gas position operating element — and/or is damped. (Only) then, the bias of the force-fit element drives, in a second step and with a certain delay and / or damping, the adjustment element, wherein movement of the adjustment element and/or the delay / damping resulting from this bias can be made dependent on a number of other structurally or apparatively specifiable constraints such as restraining forces or the like. In this way, it is possible to achieve the desired optimization as required and / or the correction of the driver’s operating errors, by means of the force-fit coupling of the gas position operating element and the adjustment element and by means of the design of other structural conditions.

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Further, the driving comfort can be improved and / or wear can be reduced because vibration of the gas operating element caused by the movement of the valves and other engine operations is reduced. These advantages are enabled, among other things, by the indirect coupling of the gas position operating element to the adjustment element and/or the support body by means of the force-fit element (e.g. intermediate spring). Further, embodiments of the valvetrain allow a mechanically simple, inexpensive, reliable and / or durable design of the valvetrain according to the invention.

Further, according to embodiments it is possible to hold the bearing of the first drive means, in spite of the forces acting thereon, in a stable manner in a sufficiently fixed position relative to the cylinder head. Further, the other benefits mentioned in DE'127 can be at least partially achieved.

The valvetrain according to the invention can be used in a particularly advantageous manner in internal combustion engines of devices or vehicles with high engine speeds, such as in motorcycles. Further, it can also be used in, e.g., automobiles, trucks, aircraft or watercraft.

Further advantages, features, aspects, details of the invention, preferred embodiments and specific aspects of the invention can be seen from the dependent claims, the description and the drawings.

Embodiments of the invention are illustrated in the drawings and are described in more detail below. In the drawings,

Figs. 1-3 show views of a valvetrain disclosed in DE'127, which is additionally provided with a control system according to the invention (not shown);

Fig. 4 shows a perspective view of a valvetrain in accordance with a further embodiment ofthe invention;

Fig. 5 shows a sectional view of the valvetrain of Fig. 4;

Fig. 6a shows a perspective view of a valvetrain in accordance with a further embodiment of the invention;

Fig. 6b shows a sectional view of portions of the valvetrain of Fig. 6a;

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Fig. 7 shows a perspective view of a portion of the valvetrain shown in Fig. 6a;

Fig. 8a is a sectional view of a valvetrain in accordance with a further embodiment of the invention;

Fig. 8b shows an enlarged detail of Fig. 8a; and

Figs. 9a and 9b respectively show a perspective view of the valvetrain shown in Fig. 8a.

Hereinafter, a valvetrain 2 according to the invention will be described with reference to

Figs. 1-3. Figs. 1-3 are contained identically in DE'127, and the shown parts are described there as well. In addition, the valvetrain 2 is equipped with a control system (not shown) according to the invention.

The valvetrain 2 shown in Figs. 1-3 comprises a driving system 10 and a transmission unit or gear unit 4. The driving system 10 provides a rotational movement. The rotational movement is preferably synchronous to the motor cycle of the combustion engine, so that one full rotation corresponds to one full motor cycle, and it is particularly preferred that the rotational movement is driven by the crank shaft of the combustion engine 1.

The transmission unit 4 transmits the rotational movement of the driving system into a lifting movement for actuating the valve 70. An actuation of the valve is herein understood to be a lifting movement of the valve 70, which opens and/or closes the valve 70, preferably synchronously to the motor cycle. :

The driving system 10 comprises a driving gearwheel 22, a valve crank gearwheel 12, and a valve crank 16 (also referred to as first driving means). The driving gearwheel 22 is mounted stationarily in the cylinder head 3b and rotatably about a driving axis 24. The valve crank gearwheel 12 is fixedly connected to the valve crank 16. The valve crank 16 and the valve crank gearwheel 12 are rotatably mounted about a valve crank axis 14 (also referred to as first rotational axis). Here and in the following, the term "axis" means a geometrical axis and/or a rotational axis. The bearing of the valve crank 16 is not shown in Fig. 1.

The driving gearwheel 22 is driven by a crank shaft of the combustion engine 1. The driving is synchronous to the motor cycle, i.e. a full rotation of the driving gearwheel 22 corresponds to a motor cycle. In a four stroke engine, this is the case if the transmission between crank shaft and driving gearwheel is 2:1.

The driving gearwheel 22 is in meshing connection with the valve crank gearwheel 12.

The transmission ratio between driving gearwheel 22 and valve crank gearwheel 121s 1:1. Thereby, also the valve crank gearwheel is driven synchronously to the motor cycle.

According to the invention, in the valvetrain shown in Fig. 1 the position of the valve crank 14 can be adjusted. The detailed mechanism for this is shown in Figs. 2-3. Therein, in addition to the elements shown in Fig. 1, a pivoting frame 80 (also referred to as support body) is visible. The pivoting frame 80 is rigid, consists in this example of several parts that are rigidly connected with one another. It is mounted on the cylinder head 3 pivotally about the pivoting axis, wherein the pivoting axis is identical to the driving axis 24 shown in Fig. 1. Further, the valve crank 16 is mounted in the pivoting frame 80, so that the pivoting of a pivoting frame 80 causes a pivoting of the valve crank axis 14, i.e. a change of the position of the valve crank axis 14 along a circular path about the pivoting axis 24.

Because the pivoting axis 24 and the driving axis are identical, it is guaranteed that the position of the valve crank axis 14 remains, in every pivoting position of the pivoting frame 80, on a circular segment about the driving axis 24. As a result, it is ensured that the valve crank gearwheel 12 mounted rotatably about the valve crank axis 14 and the driving gearwheel 22 remain in meshing connection, regardless of the pivoting position of the pivoting frame 80.

By means of a pivoting drive 84, the pivoting frame 80 can be held in a fixed position or be pivoted. The pivoting drive 84 comprises a gearwheel segment 84a, which is in fixed connection with the pivoting frame 80 and in meshing connection with a gearwheel 84b.

The pivoting frame 80 can be pivoted by moving the gearwheel segment 84a up and down by turning the gearwheel 84b. In correspondence to this function, the gearwheel segment 84a is bent along a circular segment about the pivoting axis 24.

A further detail of the pivoting drive 84 is shown in Fig. 3: In this variant, a worm gear 84c is in meshing connection with the gearwheel 84b and serves for rotating the latter. As an alternative to the worm gear 84c, the gearwheel 84b could also be driven by, e.g., a gear, a sprocket drive, a pair of bevel gearwheels, or in any other manner.

Regardless of such details, the gearwheel 84b (also referred to as adjustment element) is ultimately coupled in a manner not shown in Figs. 1-3 to a gas position operating element, the position of which is variable in dependence of a gas command. This coupling is achieved, according to the invention, via an intermediate spring as force-fit element connecting the gas position operating element in a force-fit manner to the gearwheel 84b.

The pivoting drive 84 and components serving as actuator of the pivoting drive 84 are herein also referred to as a control system. More generally, a control system is understood as all parts serving to adjust and hold the position of the first valve crank axis 14 (and thus, in this embodiment, the position of the pivoting frame 80). Also, other parts of the valvetrain which are used for periodically opening and closing the valve are referred to as an actuation system.

In the following, some general (but not mandatory) aspects of the invention are described that are illustrated in Figs. 1-3 and are explained by the reference numerals of these figures. But, these aspects can also be realized independently of the embodiment of Figs. 1-3, in conjunction with any other aspects of the invention.

According to an aspect, the valvetrain is arranged in the cylinder head portion of the combustion engine. According to a further aspect, the valvetrain (in particular, the actuation system) further comprises a connecting rod 30 with a first connecting rod joint 34 and a second connecting rod joint 36; and a guiding member 60 for guiding the connecting rod, the guiding member being pivotable around a guiding member axis 66.

According to a further aspect, the connecting rod 30 is joined with its first connecting rod joint 34 to the first driving member 16. According to a further aspect, the connecting rod 30 is joined with its second connecting rod joint 36 to the guiding member 60.

According to a further aspect, a second driving member 22 of the valvetrain is provided for driving the first driving member 16. The second driving member 22 is rotatable about a second rotation axis 24.

According to a further aspect, the second driving member 22 is a second driving gearwheel. The valvetrain comprises a first driving gearwheel 12 for driving the first driving member 16, wherein the first driving gearwheel 12 is rotatable about the first rotation axis 14.

According to a further aspect, a pushing member 40 is fastened to the guiding member oo 60. According to a further aspect, the pushing member 40 is a roller. According to a further aspect, the valvetrain 1 comprises a transmission member 50 in releasable mechanical contact with the pushing member 40. According to a further aspect, the transmission member 50 is biased, by a forcing member 58, towards the valve 70.

According to a further aspect, the combustion engine 1 comprises a fixed stop 57 for defining a maximum displacement of the transmission member 50.

According to a further aspect, the transmission member 50 is a lever, which is pivotable around a lever axis 52. According to a further aspect, the lever 50 is a one-arm lever.

According to a further aspect, a movement of the pushing member 40 toward the lever axis 52 causes the valve to open.

According to a further aspect, the valve 70 is an intake valve. According to a further aspect, the combustion engine further comprises a second intake valve 70°, which is preferably also actuated by the valvetrain.

According to a further aspect, a valve lift (a quantity characterizing valve lifting behavior) is adjustable by the adjustment of the position of the first rotation axis 14.

According to a further aspect, the quantity characterizing the valve lifting behavior 90 is a lift height, a duration of the valve opening, or both. According to a further aspect, a phase relation between a rotational angle of the first driving member 16 and an engine cycle is adjustable by the adjustment of the position of the first rotation axis 14.

According to a further aspect, the pushing member 40 is guided to follow a guided path 68, and the guided path 68 of the pushing member 40 is adjustable by the adjustment of the position of the first rotation axis 14.

According to a further aspect, the adjustment of the position of the first rotation axis 14 is a pivoting of the first rotation axis 14 around a pivoting axis 24. According to a further aspect, the combustion engine comprises: a pivoting drive 84 for pivoting the first rotation axis 14, the pivoting drive comprising a pivoting drive gearwheel 84b, which is rotatable about a third rotation axis 86, and a pivoting drive gearwheel segment 84a, which is in meshing connection with the pivoting drive gearwheel 84b.

According to a further aspect, the third rotation axis 86 is also the lever axis 52 of the lever 50.

Claims (14)

; Claims: nt? 2TR og 4 03

1. A variable valvetrain (2) for actuating a valve (70) of an internal combustion engine, comprising: an actuation system for periodically opening and closing the valve (70), the actuation system comprising a first drive means (16) mounted rotatably about a first rotational axis (14) in a support body (80) in such a manner that a position of the first rotational axis (14) is variable for adjusting a valve lift of the valve; and a control system (90, 100) comprising: - A gas position operating element (92, 102), whose position is variable in dependence on a gas command; - A movable adjustment element (95, 105) which is so coupled to the support body (80) that by movement of the adjustment element the position of the first rotational axis (14) is changed and thereby the valve lift is adjusted; and - A force-fit element (94, 104) connecting the gas position operating element (92, 102) in a force-fit manner to the adjustment element (95, 105).

2. A variable valvetrain (2) according to claim 1, wherein the adjustment element (95, 105) comprises a maximum stopper element (124) which is arranged to provide a maximum stop for limiting a maximum lift height of the valve lift, wherein the maximum stop is variable for adjusting the maximum lift height, wherein preferably the valvetrain further comprises a stopper pin (122) having an adjustable position, wherein the maximum stop is provided by the interaction of the maximum stopper element (124) with the stopper pin (122) and is variable by adjusting the position of the stopper pin (122).

3. A variable valvetrain (2) according to claim 1, wherein the adjustment element (95, 105) comprises a minimum stopper element (126) which is arranged to provide a minimum stop for limiting a minimum lift height of the valve lift, wherein the minimum stop is variable for adjusting the minimum lift height, wherein preferably the valvetrain further comprises a stopper pin (122) having an adjustable position, wherein the minimum stop is provided by the interaction of the minimum stopper

; element (124) with the stopper pin (122) and is variable by adjusting the position of the stopper pin (122).

4. A variable valvetrain (2) according to claim 1, wherein the adjustment element (95, 105) is biased in a direction of reducing the lift height by means of a return spring (96, 106).

5. A variable valvetrain (2) according to any of the preceding claims, wherein the adjustment element (95, 105) is coupled to a stationary member (112b) by means of a releasable anti-reverse mechanism (112a), wherein a blocking direction of the anti- reverse mechanism is oriented such as to block movement of the adjustment element in a lift height-decreasing direction.

6. A variable valvetrain (2) according to claim 5, wherein the anti-reverse mechanism comprises a one-way clutch (113b) defining the free-wheeling direction and the blocking direction, wherein the one-way clutch (113b) couples the adjustment element (105) to a reverse-blocking body (113a) that is lockable in place or stationary.

7. A variable valvetrain (2) according to claim 6, wherein the one-way clutch (113b) is formed as a sleeve coupling surrounding an adjustment shaft (105a) of the adjustment element (105).

8. A variable valvetrain (2) of claim 5, wherein the valvetrain further comprises a release ’ mechanism (116a, 116b) for releasing the anti-reverse mechanism (112a) upon gas removal at the gas position operating element (92, 102).

9. A variable valvetrain (2) according to claim 1, wherein the adjustment element (95) is guided longitudinally moveably in an adjustment rail (91b), and wherein the adjustment element (95) is preferably coupled to the support body (80) via a slotted guide (85a, 85b), or wherein the adjustment element (105) is rotatably mounted about an adjustment axis, and wherein the adjustment element (105) is preferably coupled to the support body (80) via an adjustment crank (105b).

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10. A variable valvetrain (2) according to claim 1, wherein the force-fit element (94, 104) comprises an intermediate spring.

11. A variable valvetrain (2) according to claim 1, wherein the support body (80) is pivotable about a pivot axis (24), wherein pivoting of the support body (80) causes a change in the position of the first rotational axis (14) along a circle segment about the pivot axis (24) for adjusting the valve lift, wherein preferably the support body (80) is mounted pivotally about the pivot axis (24) in a pivoting frame mount of a cylinder head of the internal combustion engine, and wherein the support body (80) is coupled via a joint (85) to the adjustment element (95, 105) in such a manner that a greater portion of a force exerted by the valve (70) to the support body (80) is received by the pivoting frame mount, and a lesser portion of this force is received by the adjustment element.

12. Use of the valvetrain (2) according to claim 1 in an internal combustion engine (1), wherein the valvetrain (2) is arranged in the of cylinder head region of the internal combustion engine (1).

13. Internal combustion engine (1) with a valve (70) and a valvetrain (2) according to claim 1, wherein the valvetrain (2) is arranged in the cylinder head region.

14. Internal combustion engine (50) according to claim 13, wherein the adjustment element (95, 105) comprises a maximum stopper element (124) which is arranged to provide a maximum stop for limiting a maximum lift height of the valve lift, wherein the maximum stop is variable for adjusting the maximum lift height, wherein preferably the valvetrain further comprises a stopper pin (122) having an adjustable position, wherein the maximum stop is provided by the interaction of the maximum stopper element (124) with the stopper pin (122) and is variable by adjusting the position of the stopper pin (122); the internal combustion engine (50) further comprising a positioning actuator (122a) adapted for adjusting the position of the stopper pin (122), wherein the positioning actuator (122a) is preferably controlled in dependence of an engine speed of the internal combustion engine.