Shift actuator
By designing a linear drive assembly of rotating members, electric motors and driven components in the shift actuator, combined with the cylindrical cam and spring mechanism, the actuation failure problem when the shift fork is blocked is solved, normal movement after the barrier is released is achieved, and the reliability and stability of the system are improved.
Patent Information
- Application Number
- CN202380072631.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-30
- Publication Date
- 2025-05-23
AI Technical Summary
The existing shift actuators are difficult to handle effectively when the shift fork is blocked, resulting in failure of actuation.
A linear drive assembly including a rotating member, an electric motor and a driven member is designed to store and release energy in the case of a blocking by a cylindrical cam and a spring mechanism to ensure that the driven member can move normally after the blocking is released.
The shifting fork is effectively handled, ensuring that the shifting actuator can work normally after the barrier is lifted, and improving the reliability and stability of the system.
Smart Images
Figure CN120035727A_ABST
Abstract
Description
[0001] The present invention relates to a shift actuator, which includes a linear drive assembly for actuating a shift fork through its driven component, and includes: a rotating member, which is supported to be rotatable but immovable in an axial direction defined by its rotation axis; an electric motor for rotating the rotating member; and a driven component, when the rotating member is first driven to rotate in a first rotation direction and then in a second rotation direction opposite to the first rotation direction, the driven component is driven by the rotational movement of the rotating member for linear movement from a neutral position to a first gear engagement position and back to the neutral position in the first direction parallel to the axial direction, and when the rotating member is first driven to rotate in the second rotation direction and then in the first rotation direction, the driven component is driven by the rotational movement of the rotating member for linear movement from the neutral position to the second gear engagement position and back to the neutral position in the second direction opposite to the first direction.
[0002] A shift actuator is used in a motor vehicle to shift a transmission between two coaxially arranged rotating shafts between a gear engagement position, in which a rotational engagement is established between the two rotating shafts and a torque transfer occurs, and a neutral disengagement position, in which the two rotating shafts are disconnected from each other. A typical application for a shift actuator of the above type is an actuator for a dog clutch. A dog clutch is a mechanism for connecting and disconnecting two rotating shafts. The operating principle is based on the engagement of a group of regularly spaced teeth or projections on a wheel connected to one of the shafts with a group of complementary recesses between the teeth on the other wheel connected to the second shaft. When the two wheels move together, so that the teeth of the first wheel are accommodated in the recesses formed between the teeth of the second wheel, a non-slip rotational engagement is established between the shafts. For example, a dog clutch with a dog clutch actuator is described in US2015 / 0107955 A1, on which the preamble of claim 1 is based. The shift actuator includes a linear drive assembly having: a rotating member in the form of a screw, which is supported to be rotatable but not movable in the direction of its rotation axis; an electric motor for rotating the screw; and a driven member in the form of a nut engaged by the screw. Through the engagement of the nut with the screw, the rotational movement of the screw is transmitted to the linear movement of the nut in the axial direction of the rotation axis of the screw. When the screw is driven to rotate in a first rotation direction and in a second rotation direction opposite to the first rotation direction, respectively, the driven member in the form of a nut is connected to the shift fork for driving the shift fork from a neutral position to a gear engagement position, and vice versa. In the neutral position of the shift fork, one tooth-bearing wheel moves away from the other, so that the torque transmission engagement between the two wheels stops. By moving the shift fork to the gear engagement position using the linear drive assembly, one of the two tooth or claw wheels is rotationally engaged with the teeth of the other wheel, wherein the teeth of one wheel are accommodated in a recess between the teeth of the other wheel, and vice versa.
[0003] With such a shift actuator, it may be the case that the two toothed or dog wheels are located at relative angular positions relative to one another so that the teeth of one wheel are directly facing the teeth of the other wheel, in which case the shift actuator cannot be shifted to a gear engaging position until the dog wheels are rotated relative to one another so that the dog of one wheel is aligned with the recess between the dog of the other wheel.
[0004] The object of the present invention is to provide a gearshift actuator which is designed in such a way that a temporary blocking of a gearshift fork actuated by the gearshift actuator can be handled in a simple and reliable manner.
[0005] This object is achieved by a gear shift actuator comprising the features of claim 1. Preferred embodiments of the invention are set forth in the dependent claims.
[0006] The invention relates to a gearshift actuator, comprising a linear drive assembly for actuating a gearshift fork via a driven part thereof. The linear drive assembly comprises: a rotating member, which is supported to be rotatable, but immovable in an axial direction defined by its axis of rotation (in a stationary frame of a transmission to be actuated); an electric motor for rotating the rotating member; and a driven part, which is driven by the rotational movement of the rotating member for linear movement parallel to the axial direction. The linear drive assembly is configured so that, when the rotating member is driven to rotate first in a first rotational direction and then in a second rotational direction opposite to the first rotational direction, the linear movement is realized in the first direction from a neutral position to a first gear engagement position of the driven part and back to neutral; and so that, when the rotating member is driven to rotate first in the second rotational direction and then in the first rotational direction, the linear movement is realized in the second direction opposite to the first direction from a neutral position to a second gear engagement position and back to neutral.
[0007] According to the present invention, the rotating member is a shaft that engages with first and second barrel cams, wherein the shaft and the first and second barrel cams are configured so that their engagement is torque-proof, while the first and second barrel cams are free to slide in the axial direction along the shaft. For example, when the shaft is accommodated in a through opening in the first and second barrel cams having a complementary cross-sectional shape, such engagement can be achieved by a shaft having a non-circular cross-section; preferably, the shaft is a spline shaft that engages with the complementary shaped openings in the first and second barrel cams. The first and second barrel cams are arranged between spaced first and second end stops, which are fixed in the axial direction to limit the axial movement of the first and second barrel cams along the shaft, respectively. A spring mechanism is arranged between the first and second barrel cams to separate them and bias them toward the first and second end stops, respectively.
[0008] The first and second barrel cams include first and second cam grooves on their surfaces, respectively, and the follower member carries corresponding first and second cam followers spaced apart in the axial direction and arranged to be received in the first and second cam grooves, respectively.
[0009] Each of the first and second cam grooves extends from a starting point in a circumferentially extending starting portion, the starting portion is followed by a spiral portion, the spiral portion further extending toward an outer end portion of a corresponding one of the first and second barrel cams, that is, the spiral portion of each of the first and second barrel cams turns away from the other of the first and second barrel cams. The spiral portion is continued by a circumferentially extending end portion of each of the first and second cam grooves.
[0010] The starting points of the first and second cam grooves lead to concave surface partitions of the first and second barrel cams, respectively, which allow the first and second cam followers to move in a direction parallel to the axial direction in areas between the first and second cam grooves, respectively, and inner end portions of the first and second barrel cams that are away from the first and second cam grooves. The first and second barrel cams are rotationally oriented relative to each other so that the starting portions of the first and second cam grooves are aligned and overlapped, so that when the first cam follower is in the starting portion of the first cam groove, the second cam follower is in the starting portion of the second cam groove, so that in this state:
[0011] When the rotary member rotates in the first rotational direction, the first cam groove moves along the first cam follower, so that the first cam follower is driven by its spiral portion to move the follower member in the first direction, and the second cam follower freely follows this movement in the concave surface portion of the second barrel cam,
[0012] When the rotating member rotates in the second rotational direction, the second cam groove moves along the second cam follower, so that the second cam follower is driven by the spiral portion to move the follower member in the second direction, and the first cam follower freely follows this movement in the concave surface portion of the first cylindrical cam.
[0013] By this design of the present invention, the shift actuator can handle those situations where the driven member (usually a push rod) acts on a blocked clutch. In the blocked situation, the push rod acts on the blocked clutch and therefore does not perform any linear movement. If the rotating member rotates in this state, the corresponding one of the first and second barrel cams must perform the required but blocked linear movement in the opposite direction, which moves the corresponding one of the first and second barrel cams away from its associated end stop; due to the movement of the corresponding one of the first and second barrel cams towards closer to the relative one of the first and second barrel cams, the spring mechanism acting between them is compressed. In other words, in the case of a fully blocked clutch, the drive energy of the linear drive assembly is stored in the compressed spring, and after the blocking of the clutch is released, the spring mechanism expands, thereby driving the driven member to perform the required linear movement when the corresponding one of the first and second barrel cams moves back to abut its associated end stop through the expanded spring mechanism.
[0014] In a preferred embodiment, as described above, in order to achieve torque-resistant engagement with the first and second barrel cams, the shaft has a non-circular cross-section, and the corresponding through openings of the first and second barrel cams have a cross-sectional shape complementary to the cross-section of the shaft, so that the first and second barrel cams are rotationally locked on the shaft but can slide along the shaft.
[0015] In a preferred embodiment, the first and second end stops are fixed to the shaft.
[0016] In a preferred embodiment, the first and second end stops and the first and second cylindrical cams with a spring mechanism therebetween are arranged such that the spring mechanism is under a predetermined preload and applies oppositely directed forces on the first and second cylindrical cams to bias them against the first and second end stops respectively. In other words, if one or both of the first and second end stops are removed, the arrangement of the first and second cylindrical cams and the spring mechanism therebetween will expand on the shaft.
[0017] In a preferred embodiment, the circumferentially extending end portions of each of the first and second cam grooves are continued by cam groove sections which have closed ends and inclined surfaces opposite to the inclined surfaces of the helical portions of the respective cam grooves to form locking end sections of the respective cam grooves, so that a respective one of the first and second cam followers reaches a stable end position at the closed end. In this way, the risk that the cam followers and thus the driven member may leave the intended end position due to vibration or other external disturbances is minimized. For the inclined end sections of the cam grooves, the inner walls of the respective one of the first and second cam grooves are formed with such inclined surfaces which separate the respective one of the first and second cam grooves from the respective concave surface.
[0018] In this regard, it is preferred that in the circumferential regions of the closed end cam groove sections of the first and second cam grooves, in the concave surface partitions of each of the first and second cylindrical cams, projecting surfaces are formed which project away from the opposite one of the first and second cylindrical cams, such that when one of the first and second cam followers reaches the locking end section of the respective one of the first and second cam grooves, the other of the first and second cam followers reaches the projecting surface and slides along the projecting surface, thereby further pulling one of the first and second cam followers in the axial direction into the closed end cam groove section, thus enhancing the locking effect in the first and second gear engagement end positions of the first and second cylindrical cams.
[0019] In a preferred embodiment, in each of the concave surface portions of the first and second barrel cams, a wall separating a corresponding one of the first and second cam grooves from the concave surface area at a corresponding point in the first and second cam grooves is arranged in the spiral portion of the corresponding one of the first and second cam grooves so that its outer surface facing the concave surface portion forms an additional spiral cam surface, and the additional spiral cam surface is arranged so that after a predetermined rotation angle of the first and second barrel cams, in the case where the follower member is blocked, during the rotation of the first and second barrel cams, one of the first and second cam followers that has left one of the first and second cam grooves associated therewith and entered into the concave surface portion slides onto the additional spiral cam surface and thereby further drives the follower member to overcome the blockage. In this way, it can be ensured that, in the case where the follower member is blocked, not only is the spring mechanism tensioned to store the driving force, but also, ultimately, an additional active driving force is exerted on the follower member in an attempt to actively overcome the blockage.
[0020] In this regard, it is preferred that the further spiral cam surfaces in the concave surface partitions in the first and second barrel cams are arranged so that a predetermined rotation angle from neutral, greater than the rotation angle required for the spiral portions of the first and second cam grooves to pass through the first and second cam followers, respectively, at which predetermined rotation angle the further spiral cam surfaces generate additional drive force for the follower member. In this way, it is ensured that the integrated drive force from one of the first and second barrel cams is fully stored in the compressed spring mechanism before the further spiral cam surface begins to actively add further drive force to the follower member in order to overcome the obstruction.
[0021] In a preferred embodiment, the width of the closed end sections in the first and second cam grooves is respectively enlarged and greater than the width of the first and second cam followers, thereby establishing free play for the driven component (4) relative to the first and second gear engagement positions, respectively.
[0022] In this regard, it is further preferred that, in each of the first and second concave surface partitions, the axial distance between the circumferentially extending end surface segment forming the continuation of the further spiral cam surface and the relative protruding surface is greater than the width of the first and second cam followers, respectively, thereby establishing further free clearance for the driven component relative to the first and second gear engagement positions, respectively.
[0023] In the present application, a shift actuator having oppositely directed barrel cams is described and claimed, which is capable of being moved from neutral to a first gear engaged position in a first direction and from neutral to a second gear engaged position in a second direction opposite to the first direction. However, it will be apparent to one skilled in the art that a simplified shift actuator having only such a single barrel cam can also be realized to perform the same shifting function for a single gear, i.e., a shift actuator that uses a single barrel cam and a spring between two spaced-apart end stops to enable a push rod to be driven from neutral to a gear engaged position and from the gear engaged position back to neutral.
[0024] The present invention will now be described with reference to the preferred embodiments shown in the accompanying drawings, in which:
[0025] Figure 1 A shift actuator is shown, partly in side view and partly in cross-section;
[0026] Figure 2 A side view of a shift actuator is shown, and below the side view is a schematic diagram;
[0027] Figure 3 A side view showing the shift actuator being driven from neutral to a first gear engagement position without any obstruction or jamming of the driven component is shown, and a schematic diagram is shown below the side view;
[0028] Figure 4 a) to d) show the rotational state sequence of the shift actuator when it is driven unimpeded from neutral to the first gear engagement position;
[0029] Figure 5 It shows that Figure 4 A schematic diagram showing the variation of cam follower motion (in arbitrary units) with rotational angle during operation of a shift actuator is shown;
[0030] Figure 6 a) to d) show the sequence of rotational states when the shift actuator is driven from the first gear engagement position back to neutral;
[0031] Figure 7 a) to d) show a sequence of rotational states when the shift actuator is driven from neutral toward a first gear engagement position when the driven component is temporarily blocked during the driving operation;
[0032] Figure 8 is a side view of the shift actuator with the driven member temporarily blocked during a driving operation, and below the side view is a schematic diagram;
[0033] Fig. 9a) to d) show a sequence of rotation states when the driven component is blocked and at a predetermined rotation angle the driven component is actively driven in a rigid actuation mode to overcome the blockage;
[0034] Fig.10 The driven component is still blocked after a predetermined rotation angle and the shift actuator actively drives the driven component in a rigid actuation mode to overcome the blocked state. Fig. 9 A side view of the shift actuator in the case of, and a schematic diagram below the side view; and
[0035] Fig.11 is a schematic side view of a linear drive assembly with exaggerated cross-sectional details.
[0036] Note that in most of the drawings showing the working principle of the shift actuator, such as Figure 3 , Figure 4 , Figure 6 In the figures, the cam followers 6 , 8 are shown in a simplified manner as circles, and the follower member 4 (push rod) is simplified as a thick line connecting the first and second cam followers 6 , 8 .
[0037] refer to Figure 1 and Figure 2 , the main components of the gearshift actuator and their arrangement will be outlined. The gearshift actuator comprises a rotating member 2, shown as a spline, which is supported to be rotatable but immovable in the axial direction (immovable relative to a stationary frame of a clutch to be actuated (not shown)), and Figure 1 On the right side of the figure, a cross section of a ball bearing rotatably supporting the rotating member 2 can be seen. Next to the ball bearing is shown a driven gear which is driven to rotate by an electric motor (not shown) to drive the rotating member 2 to rotate.
[0038] Figure 1 A driven component 4 is shown, here in the form of a push rod. The driven component 4 is provided with first and second cam followers 6, 8 aligned and spaced apart in the axial direction. Above the push rod, a double arrow with N in the center is shown to indicate the linear movement of the push rod from a neutral position N in a first direction to a first gear engagement position 1, and from the neutral position N in a second direction to a second gear engagement position 2. The two rotation arrows above the driven component 4 are used to illustrate that the linear movement in the first and second directions is achieved by rotating the rotating member in the first rotation direction and the second rotation direction, respectively. However, as will become clear later, it should be noted that Figure 1 The shift actuator is not shown in a neutral position, but rather the driven component 4 is in a first gear engagement position.
[0039] like Figure 2As shown, the shift actuator has two first and second barrel cams 20 and 40 with opposite orientations, that is, the first and second barrel cams 20, 40 have the same design but are oriented in opposite directions. For example, when observing their first and second cam grooves 24, 44, it can be seen that these cam grooves rotate from the starting points 26, 46 in opposite directions toward the outer end portions 35, 36 of the first and second barrel cams 20, 40.
[0040] The following, except Figure 1 In addition, reference is also made to Figure 4 a) to d). The first (second) cam groove 24 (44) of the first (second) barrel cam 20 (40) starts from a starting point 26 (46), which is continued by a circumferentially extending starting portion 28 (48). The circumferentially extending starting portions 28, 48 are aligned so that they overlap in an angled extension around the rotation axis of the rotating member 2. This arrangement ensures a specific range of rotational movement for the first and second barrel cams 20, 40, within the starting portion 26 of the first cam groove, the first cam follower 6 enters the first cam groove 24 after passing through the starting point 26, and the second cam follower 8 is also located in the starting portion 48 of the second cam groove 44. This arrangement ensures that, when the first and second barrel cams 20, 40 rotate so that the first cam groove 24 moves along the first cam follower 6 together with the circumferentially extending start portion 28, the second cam follower 8 moves toward the start point 46 along the circumferentially extending start portion 48 of the second cam groove 44, and further moves so that the second cam follower 8 leaves the second cam groove 44 and enters the concave surface partition 43 of the second barrel cam 40 before the first cam follower 6 reaches the spiral portion 30 of the first cam groove. In the concave surface partition 43 of the second barrel cam 40, as long as the second cam follower 8 remains in the area between the second cam groove 44 and the inner end portion 58 of the second barrel cam 40, the second cam follower 8 allows the second barrel cam 40 to move in the axial direction.
[0041] The first (second) cam groove 24 (44) is continued after the starting portion 28 (48) by a spiral portion 30 (50), which provides an axial force to the first (second) cam follower 6 (8) for the axial movement of the follower part 4. The spiral portion 30 (50) of the first (second) cam groove 24 (44) is followed by a circumferentially extending end portion 32 (52). The end portion 32 (52) of the first (second) cam groove 24 (44) is terminated by a closed end section 34 (54) of the first (second) cam groove 24 (44). The closed end section 34 (54) has a closed end and is slightly inclined in a direction opposite to the spiral portion 30 (50) of the first (second) cam groove 24 (44); in particular, the inclined surface can be formed by such an inclined surface of the inner wall of the first (second) cam groove, such as Figure 4 b) at 54 for the second cam groove as shown by the inclined inner wall, and at Figure 4 d) is shown at 34 for the first cam groove by the inclined inner wall. Due to this inclined surface of the closed end section 34 (54), the closed end section 34 (54) of the first (second) cam groove 24 (44) forms a locking end section so that the first (second) cam follower 6 (8) can reach a stable end position at the end of the closed end section 34 (54).
[0042] This latching effect of the first cam follower 6 in the closed end section 34 is further supported by a protruding surface 59 formed in the circumferential region of the closed end section 34 in the concave surface partition 43 of the second barrel cam 40 (see Figure 4 d) in the figure). When the first and second barrel cams 20, 40 rotate so that the first cam follower 6 reaches the closed end section 34 of the first cam groove 24, the second cam follower 8 slides onto the protruding surface 59, thereby generating a driving force on the second cam follower 8, pulling the first cam follower 6 to the bottom of the closed end section 34 of the first cam groove, thereby enhancing the locking effect when the first cam follower 6 reaches its end position (first gear engagement) to safely hold the cam followers 6, 8 at the end positions. Due to this locking mechanism, even if vibration or other external interference acts on the shift actuator, the first cam follower 6 and the second cam follower are safely held in the first and second gear engagement positions, respectively.
[0043] A spring mechanism 10 is arranged between the first and second barrel cams 20, 40, which is fixed by its opposite ends in the facing inner end portions 38, 58 of the first and second barrel cams. The dimensions of the first and second barrels (cams) 20, 40 and the spring mechanism 10 are designed so that the spring mechanism is in a preloaded state, that is, a preload force directed in opposite directions is applied to the first and second barrel cams 20, 40 to bias them against the spaced end stops 22, 42, which are fixed in the axial direction to limit the movement of the first and second barrel cams in the axial direction. In this embodiment, the first and second end stops 22, 42 are fixed to the rotating member 2, but they can in principle also be mounted on other components, which are stationary in the axial direction. It should be clear that the preload force of the spring mechanism enhances the above-mentioned blocking effect of the first and second cam followers in the first and second gear engagement positions.
[0044] Figure 3 The driving principle of the shift actuator according to the present invention is also shown. Figure 3 The first and second barrel cams 20, 40 are shown, at this time they are rotated by the rotating member 2 so that the first cam follower is in the spiral portion 30 of the first cam groove 24, and the second cam follower 8 of the follower member 4 is in the concave surface partition 43 of the second barrel cam 40, so that the second cam follower 8 can follow the linear movement of the follower member in the first axial direction, the follower member is driven by rotating the spiral portion 30 of the first barrel cam 20 relative to the first cam follower 6, and the first cam follower 6 is thereby driven to move in the first axial direction. It is noted here that the two arrows extending from the first and second cam followers 6, 8 indicate the relative movement of the cam followers 6, 8 relative to the first and second barrel cams 20, 40, wherein in fact the first and second cam followers 6, 8 are in an idle state, and the first and second barrel cams 20, 40 rotate relative to the first and second cam followers 6, 8.
[0045] exist Figure 3 In the lower part of the figure, a rather schematic illustration of the shift actuator is shown, which shows that when the first barrel cam 20 rotates along the first cam follower 6 together with the spiral portion 30 of its first cam groove, the first barrel cam 20 generates a linear driving force on the first cam follower 6 and thereby on the driven part 4 to move in the first direction.
[0046] Hereinafter, the operation of the shift actuator will be described when the shift actuator moves the driven component 4 from the neutral position to the first gear engagement position without encountering any obstruction, that is, the driven component 4 is able to follow the movement of the first cam follower 6 under the driving force generated by the rotation of the first cylindrical cam 20 and its spiral portion 30 along the first cam follower 6.
[0047] exist Figure 4 In the state a) in FIG. 1 , the first and second barrel cams have rotated so that the starting point 26 of the first cam groove 24 has passed the first cam follower 6, which is close to the end of the circumferentially extending starting portion 28 of the first cam groove 24, and the second barrel cam 40 has rotated simultaneously so that the starting portion 48 of the second cam groove 44 is almost rotated away from the second cam follower 8. Figure 4 In a), it is in a state of passing through the starting point 46 of the second cam groove and entering the concave surface partition 43 of the second cylindrical cam 40.
[0048] When the first and second cylindrical cams 20, 40 are further rotated, the spiral portion 30 of the first cam groove 24 moves along the first cam follower 6, which generates a driving force to move the first cam follower 6 in the first axial direction (in the Figure 4 At the same time, the second cam follower 8 is able to follow the movement generated by the first cam follower 6, wherein the second cam follower follows the movement in the first axial direction by corresponding movement in the concave surface partition 43 of the second barrel cam 40.
[0049] When the first and second barrel cams further rotate in the first rotational direction, the circumferentially extending end portion 32 reaches the first cam follower 6, which terminates the axial movement phase (see Figure 4 c)).
[0050] Finally, as the first and second barrel cams 20, 40 rotate further, the first cam follower 6 reaches the closed end section 34 of the first cam groove 24, which has an inclined surface toward the closed end, which is opposite to the inclined surface of the spiral cam portion 30. At the same time, the second cam follower 8 reaches the protruding surface 59 in the concave surface partition 43 of the second barrel cam 40, and by sliding along the rising surface portion of the protruding surface 59, the second cam follower 8 applies a force that pulls the first cam follower 6 to the bottom of the closed end section 34 to enhance the locking effect when the shift actuator reaches the first gear engagement position.
[0051] In the embodiment shown, the protruding surface 59 has a circumferentially extending end portion. However, in principle, the protruding surface can also be shaped so that after the circumferentially extending portion, there follows a relatively inclined end section with a reduced protruding height, which will also produce a locking depression to achieve a further locking effect.
[0052] Figure 5 The movement of the first cam follower from the neutral position to the first gear engaged position is shown. Figure 4 Graphs of the relationship between the rotation angle of the shift actuator shown in a) to d) in FIG. 1 and 2 for unimpeded operation. After a first rotation phase without linear movement of the first cam follower 6, in which the cam follower is in the circumferentially extending start portion 48 of the first cam groove, the shift position of the first cam follower rises sharply linearly with the change of the rotation angle as the spiral portion 30 in the first cam groove passes along the first cam follower, and this movement phase lasts until a rotation angle of about 155°. In the following phase, the circumferentially extending end portion 32 of the first cam groove 24 passes along the first cam follower, so that the first cam follower does not move any more until it reaches a rotation angle of about 230°, after which the first cam follower moves slightly backwards as the closed end section 34 of the first cam groove passes along the first cam follower 6, which has a slight slope opposite to the spiral portion 30 of the first cam groove to produce the above-mentioned blocking effect at the gear engagement end position of the shift actuator.
[0053] refer to Figure 6 a) to d) in the above description, the disengagement operation from the first gear engagement position to the neutral position will now be described. Figure 6 a), the first and second cylindrical cams are in the first rotation direction (which is in Figure 4 The rotation in the second rotation direction opposite to that shown in a) to d) in FIG. 1 has just started, so that the first cam follower 6 is in the stage of leaving the closed end section 34 of the first cam groove 24, while the second cam follower 8 is in the concave surface partition 43 of the second cylindrical cam and slides along the protruding surface 59. During further rotation, the circumferentially extending end portion 32 of the first cam groove passes the first cam follower 6, as shown in FIG. Figure 6 As shown in b), the second cam follower 8 is in the concave surface partition 43 of the second barrel cam 40. As the rotation continues, the spiral portion 30 of the first cam groove moves along the first cam follower 6, which causes the first cam follower 6 and the follower member to move linearly in the second axial direction from the first gear engagement position to the neutral position ( Figure 6Finally, the circumferentially extending beginning portion 48 of the second cam groove reaches the second cam follower 8, while the first cam follower 6 has passed the spiral portion 30 ( Figure 6 d)) in the figure and is about to enter the circumferentially extending starting portion 28. After a short further rotation, the neutral position is reached when the first and second cam followers 6, 8 respectively reach the circumferentially extending starting portions 28, 48 completely.
[0054] In the following, an operating scenario of a shift actuator is described in which a driven component encounters a temporary obstruction during a drive phase which is intended to move the driven component from neutral to a first gear engagement position, wherein reference is made to Figure 7 a) to d) in Figure 7 In a), the first and second barrel cams 20, 40 have just started to rotate, which makes the first cam follower 6 close to the end of the circumferentially extending starting portion 28 and close to the beginning of the spiral portion 30 of the first cam groove, while the second cam follower is close to the starting portion 46 of the second cam groove and is about to enter the concave surface partition 43 of the second barrel cam. Figure 7 b), the first and second barrel cams 20, 40 have been rotated further, so that the first cam follower 6 is already in the middle of the spiral cam portion 30 of the first cam groove, while the second cam follower 48 is in the concave surface partition 43 of the second barrel cam. Since the follower is blocked in this case, the follower and therefore also the first and second cam followers 6, 8 cannot be driven to perform linear movement in the first direction due to this blocking. Since the movement of the follower and the cam follower is blocked, the first barrel cam 20 must compensate for the passage of the first cam follower 6 through the spiral cam portion 30 by a linear movement in the second direction, which causes the first barrel cam 20 to move away from the associated first end stop 22, which causes a compression of the spring mechanism 10, because the first barrel cam has moved closer to the second barrel cam ( Figure 7 b) in ). In other words, the blocked state of the follower means that the integrated driving force generated by the rotation of the spiral portion 30 of the first cam groove relative to the first cam follower 6 is not transmitted to the movement of the blocked follower means, but is stored in the compressed spring mechanism 10. Figure 7 In the scenarios a) to d) in Figure 7After the block is released, the compressed spring mechanism 10 expands again and forces the first barrel cam 20 to return against the first end stop 22, wherein, after the block is released, the expanded spring mechanism compensates for the originally intended drive in the first direction during the blocking phase. After the block is released, the final rotation to the first gear engagement end position corresponds to an unimpeded shifting operation and can be referred to with Figure 4 d) in the description.
[0055] Figure 8 Also shown is the blocked condition of the follower member during the initial driving phase in the first direction, showing that the spiral portion 30 of the cam has moved approximately halfway along the first cam follower 6, wherein the blocked condition of the follower member and therefore the first cam follower 6 forces the first barrel cam 20 to move in the second direction opposite to the first direction, which moves the outer end portion 36 of the first barrel cam 20 away from the first end stop 22 and causes compression of the spring mechanism 10. Figure 8 , the situation is shown in a schematic manner, wherein the compressed state of the spring mechanism 10 is indicated by an arrow pointing from the spring mechanism 10 to the first barrel cam 20, which indicates the additional compression force of the spring mechanism 10 acting on the first barrel cam 20 and thus on the driven part 4 via the first cam follower 6. If a blockage now occurs during or after the drive phase, when the spiral portion 30 of the first cam groove 24 moves along the first cam follower, the expanded spring mechanism 10 is released to compensate for the previously blocked movement of the driven part in the first direction, thereby bringing the first barrel cam 20 into the first gear engagement position.
[0056] refer to Fig. 9 a) to d) in, we will now describe an operating scenario of the shift actuator in which the blocking of the driven component does not release itself but persists. Fig. 9 In a), the start of the desired driving phase is almost reached, and the spiral portion 30 of the first cam groove is close to reaching the first cam follower 6, while the second cam follower is about to enter the concave surface partition 43 of the second barrel cam. As the first and second barrel cams 20, 40 continue to rotate, as shown in FIG. Figure 7 As shown in b), the blocked follower member again forces the first barrel cam 20 to move toward the second barrel cam 40 in the second direction, thereby compressing the spring mechanism 10.
[0057] exist Fig. 9In c), the rotation of the first and second barrel cams 20, 40 continues so that the first cam follower 6 is already in the end portion 32 of the first cam groove, while the second cam follower 8 is now effective in the following manner. In the concave surface partition 43 of the second barrel cam 40, the wall of the second cam groove 44, i.e. the wall separating the second cam groove 44 from the concave surface partition 43, is in the spiral portion 50 of the second cam groove 44, which is arranged so that its outer surface facing the concave surface partition 43 forms a further spiral cam surface 60, so that after a predetermined rotation angle, in Fig. 9 In the state c), the second cam follower 8 slides onto the other spiral cam surface 60, and when the second cylindrical cam 40 rotates further, the spiral cam surface actively drives the driven member 4 in the first direction by additional force to overcome the obstruction. Fig. 9 In the scenarios shown in a) to d) of FIG. 1 , it is assumed that the resistance is overcome due to the further push of the further spiral cam surface providing additional driving force for the driven member, after which the spring mechanism 10 expands, causing the first barrel cam 20 to return to abut against the first end stop 22 ( Fig. 9 d)), after which the rotation continues for the final rotation phase until the first and second cam followers 6, 8 reach their stable end positions (first gear engaged), as shown in FIG. Figure 4 As shown in d) in the figure, and refer to Figure 4 Describe it as d).
[0058] like Figure 4 As shown in d), the other spiral cam surface 60 is continued by a circumferentially extending surface end section 62. When the shift actuator approaches Figure 4 In the first gear engagement position shown in d) in FIG. 8 , the second cam follower reaches the gap between the circumferentially extending surface end section 62 and the opposite protruding surface 59 .
[0059] exist Fig.11 , a side view of the shift actuator is shown in a schematic manner, wherein the shift actuator is in a first gear engagement position, the first cam follower 6 is in the closed end section 34 of the first cam groove, and the second cam follower 8 is located in the gap between the protruding surface 59 of the second barrel cam 40 and the circumferentially extending end surface section 62, which forms a continuation of the further spiral cam surface 60 in the concave surface partition 43 of the second barrel cam 40. Fig.11In the middle of the drawing, an enlarged detail is shown in a rather schematic manner, namely the closed end section 34 of the first barrel cam 20 and the space formed thereunder in the gap between the protruding surface 59 formed in the concave surface partition 43 and the opposite circumferential surface section 62 which is successive to the further spiral cam surface 60 in the concave surface partition of the second barrel cam 40. By reference to Fig.11 With reference to the schematic details in Figure 1, the dog mechanism which holds the shift actuator in the currently engaged gear position will now be described.
[0060] Under normal circumstances, when the shift actuator is in Fig.11 In the first gear engagement position shown in the middle, the preload force of the spring mechanism 10 causes the first barrel cam 20 and the second barrel cam 40 to separate, so that the first cam follower 6 and the second cam follower 8 are in Fig.11 The positions shown by the full circles in the middle detail. As shown, the first cam follower 6 and the second cam follower 8 have some free play in the axial direction in the corresponding positions between the opposing surfaces of the first barrel cam 20 and the second barrel cam 40. If an external force acts on the push rod, trying to pull the push rod out of the first gear engagement position toward the neutral position, the force must overcome the preload of the spring mechanism, thereby pulling the first barrel cam 20 closer to the second barrel cam 40. If such a force acts on the push rod and pulls the first barrel cam 20 closer to the second barrel cam 40, then the second cam follower 8 will be displaced the same distance in the gap of the second barrel cam 40. Eventually, the second cam follower 8 will contact the circumferential surface end section 62, which forms a hard stop so that the push rod can no longer be pulled further away from the first gear engagement position toward neutral. The position of the second cam follower 8 is schematically represented by the dotted circle. Therefore, in any case, any further displacement of the push rod from the immediate vicinity of the first gear engagement position (the extent of which is determined by the degree of free play of the cam follower in the axial direction in said position) is prevented.
[0061] As soon as the disturbing force on the push rod ceases to act on the push rod, the additional compression of the spring mechanism 10 will be released by the expansion of the spring mechanism 10, so that the push rod and its first and second cam followers 6, 8 again reach the position indicated by the cam followers 6, 8 in a complete circle, which corresponds to the first gear engagement position of the push rod.
[0062] The same operating principle applies when the shift actuator is in the second gear engagement position and the interfering force attempts to pull the push rod out of the second gear engagement position toward the neutral position. The second barrel cam 40 will then be pulled closer to the first barrel cam 20 to follow the movement of the push rod away from the second gear engagement position. When the first cam follower 6 reaches the opposite wall of the closed end section 34 of the first cam groove due to the displacement of the push rod, this movement of the push rod pulling the second barrel cam 40 closer to the first barrel cam 20 reaches the hard end stop, as shown by the dotted circle.
[0063] From the description of the design and operation of the detent mechanism as described above, it can be seen that for the interfering force directed to attempt to further pull the push rod from the gear engagement position toward neutral, it is obvious that the same function is also achieved for the interfering force directed to attempt to further push the push rod into and beyond the corresponding gear engagement position, which will also result in the hard end stop being reached at the end of the free travel of the cam follower, which prevents further compression of the spring mechanism and thus prevents the spring from moving further away from the gear engagement position; when the interfering force stops acting on the push rod, the expanded spring mechanism causes the push rod to move back to the gear engagement position.
[0064] Fig.11 The spring and line diagram on the right hand side of the drawing shows the described detent function, wherein the described hard end stops are represented by the upper solid line and the lower solid line, with a spring loaded area therebetween, allowing the push rod to move to a certain extent away from the first gear engaged position towards the neutral position or in the opposite direction, but in any case being limited by one of the two hard stops. Fig.11 The right hand side diagram of shows two relative horizontal lines and a horizontal center line between which the spring is located. The vertical axis represents the displacement of the push rod from the first gear engaged position (represented by the center line), wherein the upper solid line represents the hard stop when the force attempts to pull the push rod out of the first gear engaged position, the lower solid line represents the hard stop when the force attempts to push the push rod further into and beyond the first gear engaged position, and the center solid line represents the idle state of the push rod (with no interfering forces acting on it) in the first gear engaged position. The spring biased detent mechanism ensures that the push rod remains in the area between the two hard stops represented by the upper solid line and the lower solid line, and once the interfering forces on the push rod cease, the push rod will always return to the original engaged gear position (represented by the center horizontal line).
[0065] It is pointed out here that in the previous figures, such as Figure 4 , Figure 7 or Fig. 9 In the figure, the space between the circumferential surface end section 62 and the protruding surface 59 is shown in such a way that the second cam follower has no free play in the axial direction, but this is only for the purpose of simplifying the illustration. Fig.11 The free play explained can also be shown in other figures, such as Figure 4 , Figure 6 , Figure 7 and Fig. 9 This is achieved in the embodiment shown.
[0066] As a general comment, it should be noted that in this description, the primary focus has been on describing the operation of the shift actuator from neutral to a first gear engaged position and back to neutral. The reverse shift operation from neutral to a second gear engaged position has not been described in detail herein, but it is apparent that this operation works in the same manner as described herein in the reverse direction, with the first and second barrel cams 20, 40 reversing roles when the shift actuator shifts from neutral to the second gear engaged position and back to neutral.
Claims
1. A gear shift actuator, comprising a linear drive assembly for actuating a gear shift fork via a driven component (4) thereof, and the gear shift actuator include: a rotating member (2) supported to be rotatable but immovable in an axial direction defined by its rotation axis; An electric motor for rotating the rotating member (2); and a driven component (4) which, when the rotating member (2) is driven to rotate first in a first rotational direction and then in a second rotational direction opposite to the first rotational direction, is driven by the rotational movement of the rotating member (2) for linear movement parallel to the axial direction from a neutral position to a first gear engagement position and back to the neutral position in a first direction, and when the rotating member (2) is driven to rotate first in the second rotational direction and then in the first rotational direction, is driven by the rotational movement of the rotating member (2) for linear movement from the neutral position to a second gear engagement position and back to the neutral position in a second direction opposite to the first direction, characterized in that The rotating member (2) is a shaft, The first and second barrel cams (20, 40) are engaged with the shaft in a torque-proof manner but are free to slide along the shaft in an axial direction, and the first and second barrel cams (20, 40) are disposed between first and second end stops (22, 42) spaced apart, the first and second end stops (22, 42) being fixed in the axial direction to limit axial movement of the first and second barrel cams (20, 40), respectively, wherein a spring mechanism (10) is disposed between the first and second barrel cams (20, 40) to bias the first and second barrel cams apart and toward the first and second end stops (22, 42), respectively, The first cylindrical cam (20) and the second cylindrical cam (40) include a first cam groove (24) and a second cam groove (44) on their surfaces, respectively, and the follower member (4) carries a first cam follower (6) and a second cam follower (8), the first cam follower (6) and the second cam follower (8) being spaced apart and aligned in the axial direction and arranged to be received in the first cam groove (24) and the second cam groove (44), respectively, Each of the first cam groove (24) and the second cam groove (44) extends from a starting point (26, 46) along a circumferential starting portion (28, 48), the circumferential starting portion is followed by a spiral portion (30, 50), the spiral portion (30, 60) further extending toward an outer end portion (36, 56) of a respective one of the first barrel cam (20) and the second barrel cam (40), the spiral portion is followed by a circumferentially extending end portion (32, 52), wherein the starting points (26, 46) of the first cam groove (24) and the second cam groove (44) lead to concave surface partitions (23, 43) of the first barrel cam (20) and the second barrel cam (40), respectively, thereby allowing the first cam follower (6) and the second cam follower (8) to move in a direction parallel to the axial direction in an area between the first cam groove (24) and the second cam groove (44) and inner end portions (38, 58) of the first barrel cam (20) and the second barrel cam (40) respectively, which are away from the first cam groove (24) and the second cam groove (44), respectively, wherein the first barrel cam (20) and the second barrel cam (40) are rotationally oriented relative to each other so that the starting portions (28, 48) of the first cam slot (24) and the second cam slot (44) are aligned so that when the first cam follower (6) is in the starting portion (28) of the first cam slot (24), the second cam follower (8) is in the starting portion (48) of the second cam slot (44), so that in this state: When the rotating member (2) rotates in the first rotational direction, the first cam groove (24) moves along the first cam follower (6), so that the first cam follower (6) is driven by the spiral portion (30) to move the follower part (4) in the first direction, while the second cam follower (8) freely follows this movement in the concave surface partition (43) of the second barrel cam (40), When the rotating member (2) rotates in the second rotational direction, the second cam groove (44) moves along the second cam follower (8), so that the second cam follower (8) is driven by the spiral portion (50) to move the follower part (4) in the second direction, while the first cam follower (6) freely follows this movement in the concave surface partition (23) of the first cylindrical cam (20).
2. The shift actuator according to claim 1, It is characterized in that The shaft is a shaft with a non-circular cross-section, and the shaft is accommodated in the through openings of the first cylindrical cam (20) and the second cylindrical cam (40), and the through opening has a cross-sectional shape complementary to the cross-section of the shaft. Optionally, the shaft is a spline shaft.
3. The shift actuator according to claim 1 or 2, It is characterized in that The first end stop (22) and the second end stop (42) are fixed to the shaft.
4. A gear shift actuator according to any one of the preceding claims, It is characterized in that The distances between the first end stop (22) and the second end stop (42) and the first barrel cam (20) and the second barrel cam (40) with the spring mechanism (10) arranged therebetween are such that the spring mechanism (10) is under a predetermined preload and applies oppositely directed forces to the first barrel cam and the second barrel cam so that they are biased against the first end stop and the second end stop, respectively.
5. A gear shift actuator according to any one of the preceding claims, It is characterized in that The circumferentially extending end portion (32, 52) of each of the first cam groove (24) and the second cam groove (44) is continued by a closed end cam groove section (34, 54), and the closed end cam groove section (34, 54) has an inclined surface, and the inclined surface of the closed end cam groove section is opposite to the inclined surface of the spiral portion (30, 50) of the cam groove to form a locking end section, so that the corresponding one of the first cam follower (6) and the second cam follower (8) reaches a stable end position.
6. The shift actuator according to claim 5, It is characterized in that In the circumferential area of the closed end cam groove sections (34, 54) of the first cam groove (24) and the second cam groove (44), a protruding surface (59) is formed in the concave surface partition (23, 43) of each of the first barrel cam (20) and the second barrel cam (40), the protruding surface (59) protruding away from the opposite one of the first barrel cam (20) and the second barrel cam (40), so that when one of the first cam follower (6) and the second cam follower (8) reaches the closed end cam groove section (34, 54) of the corresponding one of the first cam groove (24) and the second cam groove (44), When the end cam groove section (34, 54) of the first and second cam followers is closed, the other of the first and second cam followers (6) (8) reaches the protruding surface (59) and slides along the protruding surface (59), so that the other of the first and second cam followers (6) (8) pulls one of the first and second cam followers (6) (8) into the closed end cam groove section (34, 54) in the axial direction to enhance the locking effect in the first gear engagement end position and the second gear engagement end position of the first and second barrel cams (20, 40).
7. A gear shift actuator according to any one of the preceding claims, It is characterized in that In each concave surface partition (23, 43) of the first barrel cam (20) and the second barrel cam (40), a wall of a respective one of the first cam groove (24) and the second cam groove (44) separating the respective one of the first cam groove (24) and the second cam groove (44) from the concave surface partition (23, 43) is arranged in the spiral portion (30, 50) of the respective one of the first cam groove (24) and the second cam groove (44) so that its outer surface facing the concave surface partition (23, 43) forms another spiral cam surface (60), so that after a predetermined rotation angle of the first barrel cam and the second barrel cam, when the follower member is blocked, one of the first cam follower (6) and the second cam follower (8) that has left one of the first cam grooves (24) and the second cam grooves (44) associated therewith during the rotation of the first barrel cam and the second barrel cam and entered the concave surface partition (23, 43) slides onto the other spiral cam surface (60), thereby driving the follower member (4) to overcome the obstruction.
8. The shift actuator according to claim 7, It is characterized in that The additional spiral cam surface (60) is arranged in the concave surface partitions (23, 43) of the first barrel cam (20) and the second barrel cam (40) so that the predetermined rotation angle starting from the neutral position is greater than the rotation angle required for the spiral portions (30, 50) of the first cam groove (24) and the second cam groove (44) to pass through the first cam follower (6) and the second cam follower (8) respectively, and in the neutral position, an additional driving force for the driven member is generated by the additional spiral cam surface.
9. A gear shift actuator according to any one of the preceding claims, It is characterized in that The widths of the closed end sections of the first cam groove (24) and the second cam groove (44) are enlarged and are respectively greater than the widths of the first cam follower (6) and the second cam follower (8), thereby establishing free play for the driven component (4) relative to the first gear engagement position and the second gear engagement position, respectively.
10. The shift actuator according to claim 9, It is characterized in that In each of the concave surface partition (23) of the first barrel cam (20) and the concave surface partition (43) of the second barrel cam (40), the axial distance between the continued circumferentially extending end surface section (62) forming the additional spiral cam surface (60) and the relative protruding surface (59) is greater than the width of the first cam follower (6) and the second cam follower (8), respectively, thereby establishing additional free clearance for the driven component (4) relative to the first gear engagement position and the second gear engagement position, respectively.
Citation Information
Patent Citations
Actuator with face dog clutch
US20150107955A1