Gear shift actuator

1 . A gear shift actuator comprising:

a linear drive assembly comprising:

a driven component configured to actuate a shift fork;

a rotary member which is supported to be rotatable, but unmovable in an axial direction defined by its a rotary axis of the rotary member; and

an electric motor configured to rotate the rotary member,

wherein the driven component is driven by rotary movement of the rotary member for linear movement parallel to the axial direction in a first direction from a neutral position to a first gear engaged position and back to neutral, when the rotary member is driven to rotate first in a first rotational direction and then in a second rotational direction opposite to the first rotational direction, and in a second direction opposite to the first direction from the neutral position to a second gear engaged position and back to neutral, when the rotary member is first driven to rotate in the second rotational direction and then in the first of rotational direction, wherein the rotary member is a shaft,

wherein first and second barrel cams are configured engage with the shaft in a torque-proof manner while being slidable in axial direction along the shaft, and

wherein the first and second barrel cams are disposed between spaced apart first and second end stops which are fixed in axial direction to limit axial movement of the first and second barrel cams, respectively,

wherein a spring mechanism is disposed between the first and second barrel cams to bias the first and second barrel cams apart and towards the first and second end stops, respectively,

wherein the first and second barrel cams comprise first and second cam grooves on surfaces thereof, respectively,

wherein the driven component carries first and second cam followers spaced apart and aligned in axial direction and arranged to be received in the first and second cam grooves, respectively,

wherein each of the first and second cam grooves extends from a starting point along a circumferential start portion, followed by a helical portion extending further towards an outer end portion of the respective one of the first and second barrel cams, which is followed by a circumferentially extending end portion,

wherein the starting points of the first and second cam grooves are open to recessed surface sectors of the first and second barrel cams, respectively, which allow movement of the first and second cam followers, respectively, in a direction parallel to the axial direction in a region between the first and second cam grooves, respectively, and an inner end portion of the first and second barrel cams remote therefrom, and

wherein the first and second barrel cams are rotationally oriented with respect to each other such that the start portions of the first and second cam grooves are aligned so that, when the first cam follower is in the start portion of the first cam groove, the second cam follower is in the start portion of the second cam groove, so that when the rotary member is then rotated in the first of rotational direction, the first cam groove is moved along the first cam follower which thereby is driven by the helical portion to move the driven component in the first direction, while the second cam follower is free to follow the movement in the recessed surface sector of the second barrel cam, is rotated in the second rotational direction, the second cam groove is moved along the second cam follower which thereby is driven by the helical portion to move the driven component in the second direction, while the first cam follower is free to follow the movement in the recessed surface sector of the first barrel cam.

2 . The gear shift actuator according to claim 1 , wherein the shaft has a non-circular cross-section and is received in throughgoing openings of the first and second barrel cams, the openings having cross-sectional shapes complementary to the non-circular cross-section of the shaft.

3 . The gear shift actuator according to claim 1 , wherein the first and second end stops are fixed to the shaft.

4 . The gear shift actuator according to claim 1 , wherein the distance between the first and second end stops and the first and second barrel cams with the spring mechanism in between are arranged such that the spring mechanism is under a predetermined preload and exerts oppositely directed forces on the first and second barrel cams to bias them against the first and second end stops, respectively.

5 . The gear shift actuator according to claim 1 , wherein the circumferentially extending end portion of each of the first and second cam grooves is continued by a closed end cam groove section which has a slope opposite to the slope of the helical cam groove portion to form a detent end section to enable the respective one of the first and second cam followers to reach a stable end position.

6 . The gear shift actuator according to claim 5 , wherein, in the circumferential region of the closed end cam groove section of the first and second cam grooves, in the recessed surface sectors of each of the first and second barrel cams, a projecting surface is formed projecting away from the opposite one of the first and second barrel cams so that, when one of the first and second cam followers reaches the closed end cam groove section of the respective one of the first and second cam grooves, the other one of the first and second cam followers reaches and slides along the projecting surface so that the other one of the first and second cam followers is pulling pulls the one of the first and second cam followers in axial direction into the closed end cam groove section to enhance the detent effect in the first and second gear engaged end positions of the first and second barrel cams.

7 . The gear shift actuator according to claim 1 , wherein, in each recessed surface sector of the first and second barrel cams, a wall of the respective one of the first and second cam grooves, that separates the respective one of the first and second cam grooves from the recessed surface sector, is in the helical portion of the respective one of the first and second cam grooves arranged such that an outer surface thereof facing the recessed surface sector forms a further helical cam surface such that, after a predetermined angle of rotation of the first and second barrel cams, in case of a blocked driven component, the one of the first and second cam followers that, during the rotation of first and second barrel cams, has left its an associated one of the first and second cam grooves into the recessed surface sector slides onto the further helical cam surface and thereby drives the driven component to overcame the blockage.

8 . The gear shift actuator according to claim 7 , wherein the further helical cam surfaces in the recessed surface sectors of the first and second barrel cams are arranged such that the predetermined rotational angle from neutral at which additional drive force for the driven component is generated by the further helical cam surface is larger than the rotational angle that is required to let the helical portion of the first and second cam grooves pass the first and second cam followers, respectively.

9 . The gear shift actuator according to claim 1 , wherein the width of the closed end sections of the first and second cam grooves is enlarged and larger than the width of the first and second cam followers, respectively, thereby establishing a free play for the driven component relative to the first and second gear engaged positions, respectively.

10 . The gear shift actuator according to claim 9 , wherein an axial distance between a circumferentially extending end surface section forming a continuation of the further helical cam surface and the opposing projecting surface in each of the first and second recessed surface sectors is larger than the width of the first and second cam followers, respectively, thereby establishing further free play for the driven component relative to the first and second gear engaged positions, respectively.

11 . The gear shift actuator according to claim 1 , wherein the shaft is a splined shaft.

12 . The gear shift actuator according to claim 2 , wherein the first and second end stops are fixed to the shaft.

13 . The gear shift actuator according to claim 2 , wherein the distance between the first and second end stops and the first and second barrel cams with the spring mechanism in between are arranged such that the spring mechanism is under a predetermined preload and exerts oppositely directed forces on the first and second barrel cams to bias them against the first and second end stops, respectively.

14 . The gear shift actuator according to claim 3 , wherein the distance between the first and second end stops and the first and second barrel cams with the spring mechanism in between are arranged such that the spring mechanism is under a predetermined preload and exerts oppositely directed forces on the first and second barrel cams to bias them against the first and second end stops, respectively.

15 . The gear shift actuator according to claim 2 , wherein the circumferentially extending end portion of each of the first and second cam grooves is continued by a closed end cam groove section which has a slope opposite to the slope of the helical cam groove portion to form a detent end section to enable the respective one of the first and second cam followers to reach a stable end position.

16 . The gear shift actuator according to claim 3 , wherein the circumferentially extending end portion of each of the first and second cam grooves is continued by a closed end cam groove section which has a slope opposite to the slope of the helical cam groove portion to form a detent end section to enable the respective one of the first and second cam followers to reach a stable end position.

17 . The gear shift actuator according to claim 4 , wherein the circumferentially extending end portion of each of the first and second cam grooves is continued by a closed end cam groove section which has a slope opposite to the slope of the helical cam groove portion to form a detent end section to enable the respective one of the first and second cam followers to reach a stable end position.

18 . The gear shift actuator according to claim 1 , wherein, in each recessed surface sector of the first and second barrel cams, a wall of the respective one of the first and second cam grooves that separates the respective one of the first and second cam grooves from the recessed surface sector is in the helical portion of the respective one of the first and second cam grooves arranged such that an outer surface thereof facing the recessed surface sector forms a further helical cam surface such that, after a predetermined angle of rotation of the first and second barrel cams, in case of a blocked driven component, the one of the first and second cam followers that, during the rotation of first and second barrel cams, has left an associated one of the first and second cam grooves into the recessed surface sector slides onto the further helical cam surface and thereby drives the driven component to overcame the blockage.

19 . The gear shift actuator according to claim 2 , wherein, in each recessed surface sector of the first and second barrel cams, a wall of the respective one of the first and second cam grooves that separates the respective one of the first and second cam grooves from the recessed surface sector is in the helical portion of the respective one of the first and second cam grooves arranged such that an outer surface thereof facing the recessed surface sector forms a further helical cam surface such that, after a predetermined angle of rotation of the first and second barrel cams, in case of a blocked driven component, the one of the first and second cam followers that, during the rotation of first and second barrel cams, has left an associated one of the first and second cam grooves into the recessed surface sector slides onto the further helical cam surface and thereby drives the driven component to overcame the blockage.

20 . The gear shift actuator according to claim 3 , wherein, in each recessed surface sector of the first and second barrel cams, a wall of the respective one of the first and second cam grooves that separates the respective one of the first and second cam grooves from the recessed surface sector is in the helical portion of the respective one of the first and second cam grooves arranged such that an outer surface thereof facing the recessed surface sector forms a further helical cam surface such that, after a predetermined angle of rotation of the first and second barrel cams, in case of a blocked driven component, the one of the first and second cam followers that, during the rotation of first and second barrel cams, has left an associated one of the first and second cam grooves into the recessed surface sector slides onto the further helical cam surface and thereby drives the driven component to overcame the blockage.