Gearbox Actuator

Abstract

To provide a gearbox actuator that accurately sets a gearbox in each gear position.SOLUTION: A gearbox actuator comprises: an electric motor 2; a shaft member 3 rotatable about a gearbox axis (X); and a transmission mechanism 4 coupled with the electric motor and couplable with the shaft member. The transmission mechanism transmits a rotation movement from the electric motor to the shaft member to bring the shaft member to selected angular positions for shifting gears. The actuator 1 is configured such that the transmission mechanism can move in a direction in which the transmission mechanism is coupled with the gear shaft member while bringing the gear shaft member to a stable gearbox position. Preferably, the actuator is configured such that the transmission mechanism reverses the movement direction and uncouples from the shaft member to create a separation gap between the shaft member and the transmission mechanism, allowing the shaft member to rotate freely to reach a stable gearbox position.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD AND OBJECTS OF THEINVENTION The present invention relates generally to actuators for shifting gears in a motor vehicle gearbox.

[0002] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to provide a gearbox actuator which accurately sets a gearbox to each gear position.

[0003] Another object of the present invention is to provide a gearbox actuator which allows free movement of the gearbox shaft in at least one of its rotational directions, by avoiding the actuator restricting the displacement of the gearbox shaft, thereby making it possible to accurately reach a stable gear position.

[0004] It is an additional object of the present invention to achieve the above object of accurate positioning of the gearbox shaft in the event of failure of power to the actuator. [Background technology]

[0005] BACKGROUND OF THEINVENTION A vehicle gear shifter includes an actuator operated by a control signal that is triggered by a gear knob operated by a driver to shift gears.

[0006] Typically, this type of actuator includes an electric motor controlled by control electronics and a transmission mechanism that transfers the rotational motion of the motor shaft into a translational motion that is transferred to a gearbox shaft that shifts the gears by rotating between gear positions.

[0007] To define stable gear positions, a contoured surface with alternating valleys and peaks is conventionally used, and a roller moves against the surface, such that stable gear positions are defined in the lowest regions of the valleys. These stable positions are conventionally realized by a roller ball exerting pressure against the contoured surface, for example by using a spring, strap or similar element to hold the roller ball against the surface.

[0008] The undulating surface is attached to the gearbox shaft and rotated by an actuator to reach pre-set rotational angles corresponding to each stable gear position, such as neutral, drive, reverse and park.

[0009] The accuracy in reaching a stable gear position is dependent on the tolerances of the actuator components, the accuracy of the actuator positioning, and the manufacturing tolerances of the gearbox stable position mechanism.

[0010] Additionally, the cogging torque of the electric motor and the efficiency of the gears can limit the position of the gearbox shaft.

[0011] Thus, as a result of tolerances, cogging, efficiency of system elements, and precision of actuator positioning, the gearbox shaft could not be properly positioned at the bottom of the valley. Summary of the Invention

[0012] (Summary of the invention) The present invention is defined in the accompanying independent claims and refers to a gearbox actuator, preferably a reversible gearbox actuator, which typically includes an electric motor and a shaft member rotatable about a gearbox axis (X) and is adapted for mechanical connection with a gearbox shaft of a motor vehicle.

[0013] The actuator further comprises a transmission mechanism coupled to the electric motor, the transmission mechanism being coupleable to the shaft member for transmitting rotational motion from the electric motor to the shaft member, and capable of bringing the shaft member into a selected angular position for shifting gears in the gearbox when the actuator is mounted on a vehicle.

[0014] The shaft member of the present invention, when coupled with a gearbox shaft of an automobile, must be rotated between different gear stable positions such as neutral, drive, park, reverse, out of park, etc., where the gearbox shaft remains stable, i.e., the shaft member does not rotate unless an appropriate force is applied. Transition or unstable positions are those positions where the gearbox shaft rotates and does not remain in a fixed position when moving from one stable position to another.

[0015] According to the invention, the actuator is configured to allow the transmission mechanism to move in the direction in which it is coupled, i.e. so that it can contact the shaft member to bring the gear shaft member into the gearbox position. Furthermore, the actuator is configured to disengage the transmission mechanism from the shaft member at a predetermined angular position of the shaft member, allowing the shaft member to rotate freely to reach a stable gear position by itself (pressed against the undulating surface by elastic means). Preferably, the actuator is configured to reverse the direction of movement to disengage from the shaft member and create a separation gap between the shaft member and the transmission mechanism, so that the shaft member can rotate freely in both directions to reach a stable gearbox position if it has not yet reached the stable position.

[0016] The actuator is configured to disengage the transmission mechanism from the shaft member when the shaft member is in an unstable position and is attempting to reach a stable position, e.g., to stop the transmission mechanism in order to rotate the shaft member to a stable position. Preferably, the actuator is configured to reverse the direction of movement of the transmission mechanism to disengage from the shaft member.

[0017] A reversible gearbox actuator operates in the same way, further incorporating an electronic controller electrically connected to the electric motor, i.e., driving the motor and selecting the direction of rotation of the motor shaft. Thus, the electronic controller is adapted to reverse the direction of rotation of the electric motor shaft for a determined angular displacement in order to reverse the direction of movement of the transmission mechanism and decouple it from the shaft member.

[0018] In addition to the conventional operation of the controller to drive the electric motor, the controller is adapted for reverse motion to release the shaft member, which may also be effected by a biasing means as described below.

[0019] In a preferred embodiment, the controller is equipped with a table that indicates which values ​​or ranges of values ​​the different gears can be placed at, e.g., a degree of freedom for a downward slope towards the valley, two degrees of freedom between a downward slope and an upward slope (retracting the drive wheels).

[0020] The invention thus enables the automotive gearbox shaft to accurately reach a gear position by avoiding the actuator restricting the movement of the gearbox shaft due to, for example, manufacturing tolerances of components, and where a transmission mechanism permanently engages the shaft member, as is the case with prior art actuators.

[0021] The transmission mechanism includes a drive wheel mechanism, a worm or any other transmission element meshed with the electric motor shaft, and a drive wheel meshed with the worm or any other transmission element, the drive wheel being connectable (by contacting) with the shaft member such that rotation of the electric motor shaft is transmitted to the shaft member for shifting the gears.

[0022] Additionally, the shaft member has a first contact surface extending radially from the gearbox axis (X), and the drive wheel has a protrusion contactable with the first contact surface of the shaft member to rotate the shaft member.

[0023] When the shaft member is about to reach a stable gear position, the rotation of the drive wheel can be reversed to decouple the drive wheel from the shaft member, so that the shaft member is decoupled from the transmission mechanism and free to rotate through a predefined angle or in both directions.

[0024] In a preferred embodiment, the worm is parallel to the electric motor shaft and the transmission mechanism further comprises a toothed wheel axially attached to the worm and meshing with the electric motor shaft. This arrangement is advantageous in that it provides a compact (reduced volume) actuator.

[0025] Preferably, the actuator comprises biasing means arranged to bias the drive wheel in both directions of rotation, i.e. clockwise and counterclockwise. Biasing means are provided to move the drive wheel in the opposite direction to the motor direction movement, decoupling it from the shaft member and keeping the shaft member free in both directions. In this way, in the gearbox, the rollers sliding over an undulating surface with constant pressure can slide towards the bottom in a stable position.

[0026] Preferably the biasing means is a torsion spring attached to the drive wheel, with both ends of the torsion spring attached to the drive wheel and the torsion spring being attached to a fixed part of the actuator, for example a casing of the actuator.

[0027] The axis of rotation (Y) of the drive wheel is parallel to the gearbox axis (X), where the projection of the drive wheel is a first arm, and the arm of the shaft member and the first arm of the drive wheel are in the same plane. The axis of rotation (Y) of the drive wheel is perpendicular to the plane in which both arms are located.

[0028] Preferably, the drive wheel has a second contact surface. The arm of the shaft member is disposed between the first and second contact surfaces of the drive wheel such that the first and second contact surfaces can alternately contact the shaft arm. [Brief description of the drawings]

[0029] BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

[0030] [Figure 1] Figure 1 shows in Fig. 1A a perspective view from above of an exemplary embodiment of a gearbox actuator according to the present invention, and in Fig. 1B another perspective view from above of the same device, but without the electric motor shown. [Diagram 2] FIG. 2 shows, in Fig. 2A and Fig. 2B, two different perspective views from below of the same device of Fig. 1, but without the electric motor. [Diagram 3] FIG. 3 shows a perspective view of the same actuator including the electronic circuitry. [Figure 4] FIG. 4 shows a perspective view of an alternative implementation of the actuator in FIG. 4A and a top view in FIG. 4B. [Figure 5-1]Figure 5 shows a bottom view of the actuator in four different successive positions of the transmission mechanism (Figures 5A-5G): Figure 5-1 shows the case when the drive wheel is rotating clockwise (as shown in Figures 5A-5D). [Figure 5-2] Figure 5-2 shows the case where the drive wheel is rotating counterclockwise (as shown in Figures 5E-5G). [Figure 6] FIG. 6 shows top views of two alternative transmission mechanisms in FIGS. 6A and 6B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Preferred embodiments of the invention FIG. 1 (FIGS. 1A, 1B) shows an exemplary implementation of a gearbox actuator (1) of the present invention, comprising an electric motor (2) and a shaft member (3) rotatable about a gearbox axis (X) and adapted for mechanical connection with a gearbox shaft (not shown) of a motor vehicle.

[0032] The actuator (1) includes a transmission mechanism (4) coupled to the electric motor (2) and matable with the shaft member (3) for transmitting rotational motion from the electric motor (2) to the shaft member (3). To shift the gears, the shaft member (3) can be moved to a selected angular position.

[0033] The transmission mechanism (4) comprises a worm (5) meshing with an electric motor shaft (6), in particular with a pinion (7) attached to the motor shaft (6), and a drive wheel (8) meshing in a known manner with the worm (5). The drive wheel (8) can be coupled to a shaft member (3) such that, when coupled to a gearbox shaft of a motor vehicle, the rotation of the shaft (6) of the electric motor (2) is transmitted to the shaft member (3), which in turn causes a gear shift.

[0034] As shown in the figure, the worm (5) is parallel to the electric motor shaft (6), and the transmission mechanism (4) further includes a gear (10) axially mounted on the worm (5) and meshing with the pinion (7) of the electric motor.

[0035] For the connection between the shaft member (3) and the drive wheel (8), the shaft member (3) has at least one arm (9) extending radially from the gearbox axis (X) and the drive wheel (8) has at least one protrusion engageable with the arm (9) to push the shaft member (3) and rotate it. The arm (9) has a curved lobe (13) at its free end for sliding against the drive wheel (8), which helps reduce friction between the two elements.

[0036] The axis of rotation (Y) of the drive wheel (8) is parallel to the gearbox axis (X), which is also the axis of the shaft member (3). The projection of the drive wheel (8) comprises a first arm (11), which is arranged so that the arm (9) of the shaft member (3) and the arm (11) of the drive wheel (8) are coplanar (i.e. the surface of the arm (9) and the surface of the arm (11) are movable in the same plane). The axis of rotation (Y) of the drive wheel (8) is perpendicular to the plane in which both arms (9, 11) are arranged, as shown more clearly in Figure 2 (2A).

[0037] The drive wheel (8) may include a second arm (12) that is also flush with the first arm (11) and the arm (9) of the shaft member (3). The arm (9) of the shaft member (3) is disposed between the first and second arms (11, 12) of the drive wheel (8) such that the first and second arms (11, 12) alternatively contact the arm (9) of the shaft member (3) depending on the direction of rotation of the drive wheel (8).

[0038] The separation distance between the two arms (11, 12) of the drive wheel (8) allows the arm (9) of the shaft member (3) to move freely in any direction of movement of the drive wheel (8).

[0039] As shown in Figure 3, the actuator (1) incorporates a housing (20) within which the transmission mechanism (4), the electric motor (2) and the drive wheel (8) are at least partially enclosed. The actuator (1) also includes a printed circuit board (PCB) (19) mounted to the housing (20).

[0040] The electric motor controller may be implemented on the same (PCB) (19). In other preferred embodiments, the controller may be a separate device located in a different vehicle location than the actuators, or may be implemented with the vehicle's other electronics. The controller communicates with the electric motor (2) to operate in the same manner, i.e. to rotate the motor's shaft (6) in an angular direction. This rotation is transmitted by the transmission mechanism (4) to the shaft member (3), rotating it clockwise or counterclockwise to bring the gearbox shaft member into a stable gearbox position.

[0041] In a preferred embodiment, the electronic control device is adapted to reverse the direction of rotation of the electric motor shaft (6) for a determined angular displacement in order to reverse the movement of the transmission mechanism (4), in particular to reverse the direction of rotation of the drive wheel (8) and thus to decouple the same from the shaft member (3), so that the shaft member (3) can rotate freely or with a certain rotation angle to reach a stable gear position in both directions.

[0042] An additional advantage of decoupling the shaft member (3) and the transmission mechanism (4) is that there is more freedom to use different types of electric motors in the practical implementation of the invention.

[0043] Preferably, the actuator is configured such that the transmission mechanism (4) reverses its direction of movement and disengages from the shaft member (3) in any rotational direction, thereby creating a separation gap between the shaft member (3) and the transmission mechanism (4), allowing the shaft member (3) to rotate freely and reach a stable gearbox position.

[0044] Biasing means are provided within the actuator such that the drive wheel (8) is rotatable against the action of the biasing means. In this embodiment, the biasing means is embodied as a torsion spring (14) associated with the drive wheel (8), the two free ends (15, 15') of the torsion spring (14) being attached to the drive wheel (8) as shown in Figure 1 (view 1A) and also to a fixed part of the actuator (1), preferably the housing (20).

[0045] To rotate the drive wheel (8) in any direction, the torque applied by the electric motor (2) through the transmission mechanism (4) is selected to overcome the elastic force of the torsion spring (14). Furthermore, in order for the torsion spring (14) to move the drive wheel (8), the force of the torsion spring (14) must be greater than the various frictions that exist from the drive wheel (8) to the motor shaft (6).

[0046] As shown more clearly in Figures 2A and 2B, each of the first and second arms (11, 12) of the drive wheel (8) has a contact surface (11a, 12a) provided for contacting the shaft arm (9). The contact surface (11a) of the first arm (11) has a wavy configuration, while the contact surface (12a) of the second arm (12) is flat.

[0047] The wavy configuration of one of those contact surfaces (9a, 11a, 12a) can provide a variable ratio during contact between the arm (9) and the first arm (11) or the second arm (12), allowing more load to be realized in a certain angular stroke range, which is necessary for example for disengagement of the gear from the park gear position.

[0048] Alternatively, as in the case of the embodiment of FIG. 4 which provides the same effect as above, the wavy surface can be provided on the contact surface (12a) of the second arm (12) or even on the contact surface (9a) of the arm (9) of the shaft member (3).

[0049] As shown in Figure 3, the PCB (19) incorporates a first rotation sensor (16) and preferably a second rotation sensor (16') positioned to sense the rotation of the axes (X, Y) of the respective shaft members (3) and drive wheels (8). These two rotation sensors (16, 16') detect the position of the respective axes (X, Y) and can optimize the operating parameters of the motor based on the working regions of coupling and decoupling.

[0050] The signals from one or both sensors can be used as information redundancy to make it more certain that the actuator correctly positions the gearbox according to the driver's commands. To constantly control the actuator / gearbox system, the gearbox shaft position is compared with the drive wheel shaft position.

[0051] In the alternative embodiment of Figure 4, instead of the arms (11, 12), the drive wheel (8) has two pegs (17, 18) provided for contacting the arms (9) of the shaft member (3). The arm (9) is disposed between the two pegs (17, 18) and has two opposing wavy surfaces (9a, 9b) along which the pegs (17, 18) can slide.

[0052] The operation of the transmission mechanism is shown in the sequence of Figures 5-1 and 5-2. As shown in Figures 5A-5D, when the drive wheel (8) rotates clockwise, the arm (12) contacts (couples) the arm (9) and rotates the shaft member (3) counterclockwise to move the shaft member (3) closer to the gear shift position (see figure). At the position shown in Figure 5E, the drive wheel (8) is disengaged from the arm (9), so that the shaft member (3) rotates freely in both directions. In Figures 5F and 5G, when the drive wheel (8) rotates counterclockwise, the arm (11) of the drive wheel (8) contacts the arm (9) and rotates the shaft member (3) clockwise (see figure).

[0053] Further preferred embodiments of the invention are set forth in the dependent claims and in combinations of these claims.

Claims

1. An electric motor (2), a shaft member (3) rotatable about a gearbox axis (X) and adapted for mechanical connection with a gearbox shaft of a motor vehicle; a transmission mechanism (4) coupled to the electric motor (2) and connectable to the shaft member (3), for transmitting rotational motion from the electric motor (2) to the shaft member (3) to bring the shaft member (3) to a selected angular position for shifting gears; A gearbox actuator (1) comprising: the gearbox actuator (1) is configured such that the transmission mechanism (4) can be actuated in a direction in which the transmission mechanism (4) engages with the shaft member (3) in one rotational direction to rotate the shaft member (3) towards a gearbox position; The gearbox actuator (1) includes an electronic controller electrically connected to the electric motor (2) for operating the electric motor (2). Further preparation, said electronic controller is adapted to decouple said transmission mechanism (4) from said shaft member (3) so that said shaft member (3) can rotate freely to reach a stable gear position; the electronic controller is adapted to reverse the direction of rotation of the shaft (6) of the electric motor (2) for the determined angular displacement in order to reverse the movement of the transmission mechanism (4) and decouple it from the shaft member (3) so that the shaft member (3) can rotate freely to reach the stable gear position in both directions; said gearbox actuator (1) is configured such that said transmission mechanism (4) reverses its direction of movement and disengages from said shaft member (3) to create a separation gap between said shaft member (3) and said transmission mechanism (4), thereby allowing said shaft member (3) to rotate freely and reach said stable gearbox position; A gearbox actuator (1), wherein the transmission mechanism (4) is rotatable by the electric motor (2) and comprises a drive wheel (8) engageable with the shaft member (3) so that rotation of the shaft (6) of the electric motor (2) can be transmitted to the shaft member (3) to shift the gears.

2. A gearbox actuator (1) as claimed in claim 1, wherein the shaft member (3) has arms (9) extending radially from the gearbox axis (X).

3. A gearbox actuator (1) as claimed in claim 2, wherein the drive wheel (8) has a protrusion engageable with the arm (9) of the shaft member (3) to rotate the shaft member (3).

4. 3. The gearbox actuator (1) according to claim 1 or 2, wherein the transmission mechanism (4) includes a worm (5) meshing with the shaft (6) and the drive wheel (8) of the electric motor (2), the worm (5) being parallel to the shaft (6) of the electric motor (2), and the transmission mechanism (4) further comprises a gear (10) axially attached to the worm (5) and meshing with the shaft (6) of the electric motor (2).

5. a biasing means configured to bias the drive wheel (8); In addition, A gearbox actuator (1) according to claim 2 or 3, wherein the drive wheel (8) is rotatable in both directions by the electric motor (2) against the action of the biasing means.

6. the biasing means being a torsion spring (14) coupled to the drive wheel (8); Gearbox actuator (1) according to claim 5, wherein both ends (15, 15') of the torsion spring (14) are attached to the drive wheel (8) and to a fixed part of the gearbox actuator (1).

7. 4. The gearbox actuator (1) according to claim 3, wherein the rotation axis (Y) of the drive wheel (8) is parallel to the gearbox axis (X), the protrusion of the drive wheel (8) is a first arm (11), and the arm (9) of the shaft member (3) and the first arm (11) of the drive wheel (8) are on the same plane.

8. 8. A gearbox actuator (1) according to claim 7, wherein the drive wheel (8) has a second arm (12) which is also coplanar with the first arm (11) and with the arm (9) of the shaft member (3), the arm (9) of the shaft member (3) being disposed between the first and second arms (11, 12) of the drive wheel (8) such that the first and second arms (11, 12) can alternatively contact the arm (9).

9. 9. A gearbox actuator (1) according to claim 8, wherein the rotation axis (Y) of the drive wheel (8) is perpendicular to a plane in which both the first and second arms (11, 12) are arranged.

10. 9. A gearbox actuator (1) according to claim 8, wherein each of the first and second arms (11, 12) of the drive wheel (8) has a contact surface (11a, 12a) provided for contacting the arm (9) of the shaft member (3), one of the contact surfaces being flat and the other of the contact surfaces being wavy.

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