Shift actuator and assembling method

Abstract

Disclosed are a shift actuator and an assembling method. The shift actuator comprises a housing (10), a motor (20), and a ball screw (30). The motor comprises a stator (21), a rotor (22), and a motor shaft (23); the rotor is rotatably arranged on the radial inner side of the stator; the motor shaft axially passes through the rotor from the radial inner side and is fixed relative to the rotor; the motor shaft is transmittingly connected to the ball screw; the housing comprises an inner cavity used for accommodating the motor; and the stator is directly fixed in the inner cavity of the housing in such a manner that the stator is in contact with the inner wall of the housing. The shift actuator and the assembling method have improved layout.

Description

Gear shift actuator and assembly method Technical Field

[0001] The present invention relates to the field of vehicle technology, and in particular to a gear shift actuator and an assembly method. Background Art

[0002] In current electric vehicles, a motor-driven shift fork is typically used to achieve gear shifting. This shift actuator consists of a motor, transmission gears, and a ball screw. The motor shaft is connected to a bevel gear, while the ball screw is connected to a face gear. When the motor is running, torque is transmitted via the bevel gear to the face gear, driving the ball screw to rotate. The ball screw converts the screw's rotational motion into linear motion of the ball screw nut. The shift fork moves along with the ball screw nut, achieving gear shifting.

[0003] Existing shift actuators typically utilize off-the-shelf motor assemblies. The stator and rotor components of these motor assemblies are enclosed in a separate motor housing, which is then integrally mounted within the shift actuator housing. This motor is not only small in size but also relatively expensive. Furthermore, existing shift actuators lack a local control unit for the motor, requiring a separate controller to control its operation.

[0004] Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide an improved shift actuator and assembly method.

[0006] The above technical problems are solved by a shift actuator according to the present invention. The shift actuator includes a housing, a motor, and a ball screw. The motor includes a stator, a rotor, and a motor shaft. The rotor is rotatably arranged on the radial inner side of the stator. The motor shaft passes through the rotor axially from the radial inner side and is fixed relative to the rotor. The motor shaft is transmission-connected to the ball screw. The housing includes an inner cavity for accommodating the motor. The stator is directly fixed in the inner cavity of the housing in a manner that contacts the inner wall of the housing. Since a separate motor housing is omitted and the motor is directly installed in the housing of the shift actuator, a larger motor can be used, and mass-produced motors that have been used in other mature products can be directly used, thereby saving costs.

[0007] According to a preferred embodiment of the present invention, the shift actuator may include a control unit for controlling the motor. The inner cavity of the housing includes an axially open end, and the motor can be installed in the housing through the open end. The axial end of the motor shaft facing away from the open end is connected to the ball screw drive system. The control unit is installed in the open end, thereby encapsulating the motor in the housing. The control unit directly mounted on the housing facilitates control of the motor's operation and also serves to encapsulate the motor.

[0008] According to another preferred embodiment of the present invention, the shift actuator may include a position sensor for detecting the rotational position of the motor, the position sensor being mounted on an axial end portion of the motor shaft facing the open end. The motor rotational position signal acquired by the position sensor may be provided to a control unit for controlling operation of the motor.

[0009] According to another preferred embodiment of the present invention, the shift actuator may include a retaining sleeve fixed to an axial end portion of the motor shaft facing the open end, and the position sensor may be fixed to the motor shaft via the retaining sleeve, thereby retaining the position sensor on the motor shaft.

[0010] According to another preferred embodiment of the present invention, the shift actuator may include a bearing mounted on a portion of the motor shaft that extends axially away from the open end and extends beyond the rotor. The motor shaft is supported within the inner cavity of the housing via the bearing, thereby maintaining the position of the motor shaft within the housing.

[0011] According to another preferred embodiment of the present invention, the motor shaft may include a flange, the inner ring of the bearing and the rotor axially abutting opposite sides of the flange, and the outer ring of the bearing abutting the housing axially away from the flange. The housing may provide axial restraint for the motor shaft and rotor via the bearing.

[0012] The above technical problem is solved by an assembly method for the above-mentioned shift actuator according to the present invention. The assembly method comprises: installing the stator within a housing; assembling the rotor, motor shaft, position sensor, and bearings into a subassembly; mounting the subassembly radially inwardly of the stator; and mounting the control unit to the housing. Because the relevant components on the motor shaft can be preassembled outside the housing, the assembly steps are simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention is further described below with reference to the accompanying drawings. Elements with the same function are represented by the same reference numerals in the drawings.

[0014] FIG1 shows a perspective view of a shift actuator according to an exemplary embodiment of the present invention;

[0015] FIG2 shows a cross-sectional view of a shift actuator according to an exemplary embodiment of the present invention; and

[0016] FIG. 3 shows a cross-sectional view of a subassembly of a shift actuator according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following description and accompanying drawings are provided to illustrate the principles of the present invention. The present invention is not limited to the preferred embodiments described. The scope of protection of the present invention is defined by the following claims.

[0018] According to an embodiment of the present invention, a shift actuator for a motor vehicle is provided. The shift actuator is used to drive a shift fork of the motor vehicle, thereby controlling the vehicle's shifting process. Figures 1 to 3 show exemplary embodiments of the shift actuator according to the present invention.

[0019] Figures 1 and 2 respectively show a perspective view and a cross-sectional view of a shift actuator according to an exemplary embodiment of the present invention. As shown in Figures 1 and 2 , the shift actuator primarily comprises a housing 10, a motor 20, and a ball screw 30. Housing 10 includes an interior cavity for accommodating motor 20, which is mounted within the interior cavity of housing 10. Ball screw 30 is also mounted within housing 10.

[0020] The motor 20 includes a stator 21, a rotor 22, and a motor shaft 23. The stator 21 is generally cylindrical and is directly fixed within the inner cavity of the housing 10, contacting the inner wall of the housing 10. For example, the stator 21 can be fixed to the inner wall of the housing 10 by means of an interference fit, adhesive bonding, or the like. This eliminates the need for a separate housing specifically for the motor 20. The inner cavity of the housing 10 may include two axially opposed ends, with the end distal to the ball screw 30 being open and the end proximal to the ball screw 30 being closed. The motor 20 can be installed within the housing 10 from the open end of the inner cavity. The rotor 22 is generally cylindrical and coaxially arranged radially inward of the stator 21 and rotatable relative to the stator 21 about a central axis. The motor shaft 23 is generally elongated and cylindrical and is fixed to the rotor 22 (e.g., by means of an interference fit, adhesive bonding, welding, etc.). The motor shaft 23 has a smaller diameter than the rotor 22 and passes axially through the rotor 22 from the radially inner side. When the motor 20 is started, the electromagnetic force generated drives the rotor 22 and the motor shaft 23 to rotate about the central axis relative to the stator 21. The axial ends of the motor shaft 23 extend axially out of the rotor 22. The axial end of the open end, facing away from the inner cavity, can extend out of the inner cavity from the closed end and be connected to the ball screw 30 via a transmission gear.

[0021] The ball screw 30 includes a lead screw 31 and a lead screw nut 32. The lead screw nut 32 is rotatably supported on the housing 10 and disposed outside the inner cavity. The axial direction of the lead screw nut 32 is perpendicular to the axial direction of the motor shaft 23. The lead screw nut 32 is mounted radially outward from the lead screw 31 and is capable of axial movement along the lead screw 31 as the lead screw 31 rotates.

[0022] A bevel gear 41 is coaxially fixedly mounted on the motor shaft 23 , and a face gear 42 is coaxially fixedly mounted on the lead screw 31 . The bevel gear 41 and the face gear 42 mesh with each other with their axes orthogonal to each other, thereby transmitting the rotation of the motor shaft 23 to the orthogonal lead screw 31 .

[0023] Preferably, the shift actuator may further include a control unit 50. The control unit 50 may control the operation of the motor 20. The control unit 50 is mounted at the open end of the inner cavity to seal the inner cavity and is fixed to the housing 10 (e.g., by means of an interference fit, adhesive bonding, etc.). The motor 20 is thus encapsulated within the inner cavity of the housing 10 by the control unit 50. The circuitry of the motor 20 may be connected to the control unit 50, allowing the control unit 50 to control the motor 20.

[0024] Preferably, the shift actuator may further include a position sensor 60 for detecting the rotational position of the motor 20. As shown in FIG2 , the position sensor 60 is mounted on the axial end portion of the motor shaft 23 that faces the open end, thereby facing the control unit 50. The control unit 50 can obtain a signal regarding the rotational position of the motor 20 through the position sensor 60. The position sensor 60 may be formed of a magnet. Preferably, the position sensor 60 may be fixed to the axial end portion of the motor shaft 23 by a retaining sleeve 70. The retaining sleeve 70 may be generally cylindrical, with one axial end thereof clamped onto the motor shaft 23 and the other end engaging the position sensor 60.

[0025] The motor shaft 23 is preferably further supported within the inner cavity of the housing 10 via a bearing 80. Specifically, as shown in FIG2 , the bearing 80 is mounted on the portion of the motor shaft 23 that extends axially away from the open end and beyond the rotor 22. The bearing 80 is preferably a ball bearing. A flange 23a is formed on the portion of the motor shaft 23 that extends axially away from the open end and beyond the rotor 22. The flange 23a surrounds the outer surface of the motor shaft 23 around the central axis. The inner ring of the bearing 80 and the rotor 22 axially abut on opposite sides of the flange 23a, while the outer ring of the bearing 80 abuts the housing 10 axially away from the flange 23a. The motor shaft 23 and rotor 22 are thus axially supported on the housing 10 via the flange 23a and the bearing 80. The bearing 80 is axially located between the flange 23a and the bevel gear 41 and is axially spaced apart from the bevel gear 41.

[0026] According to another embodiment of the present invention, an assembly method for the aforementioned shift actuator is provided. In this assembly method, the stator 21 is first installed within the housing 10, securing it in place within the inner cavity of the housing 10. Then, as shown in FIG3 , the rotor 22, motor shaft 23, position sensor 60 (including retaining sleeve 70), and bearing 80 are assembled into a subassembly. First, the bearing 80 and rotor 22 are assembled onto the motor shaft 23 from opposite sides of the flange 23a. Then, the position sensor 60 is mounted onto the axial end of the motor shaft 23 proximal to the rotor 22 using the retaining sleeve 70, thereby forming the subassembly. The order of these two steps (installing the stator 21 and assembling the subassembly) can be reversed or performed simultaneously. Next, the subassembly is mounted radially inwardly of the stator 21 within the housing 10. Finally, the control unit 50 is mounted onto the housing 10 and secured together. This completes the assembly of the shift actuator.

[0027] The shift actuator and assembly method according to the present invention eliminate the need for a separate housing specifically for the motor. This allows for the use of larger motors, particularly mass-produced motors already used in other devices, saving production costs. Furthermore, the shift actuator integrates a separate control unit to facilitate motor control. Furthermore, components related to the motor's rotor can be preassembled into subassemblies outside the housing and then installed within it, simplifying the assembly process.

[0028] While the foregoing descriptions illustrate possible embodiments, it should be understood that numerous variations exist through combinations of all known and other technical features and implementations readily conceivable to a skilled artisan. Furthermore, it should be understood that the exemplary embodiments serve merely as examples and in no way limit the scope, application, or configuration of the present invention. The foregoing descriptions are intended primarily to provide a skilled artisan with technical guidance for implementing at least one exemplary embodiment. Various modifications, particularly regarding the functionality and structure of the components described, may be made without departing from the scope of the claims.

[0029] Reference Signs

[0030] 10 Housing

[0031] 20 motors

[0032] 21 stator

[0033] 22 rotors

[0034] 23 Motor shaft

[0035] 23a Flange

[0036] 30 Ball Screw

[0037] 31 Screw

[0038] 32 Screw nut

[0039] 41 bevel gear

[0040] 42 plane gear

[0041] 50 control unit

[0042] 60 Position Sensor

[0043] 70 retaining sleeve

[0044] 80 bearings

Claims

1. A shift actuator, comprising a housing (10), a motor (20) and a ball screw (30), wherein the motor (20) comprises a stator (21), a rotor (22) and a motor shaft (23), wherein the rotor (22) is rotatably arranged on the radial inner side of the stator (21), the motor shaft (23) passes through the rotor (22) axially from the radial inner side and is fixed relative to the rotor (22), the motor shaft (23) is drivingly connected to the ball screw (30), and the housing (10) comprises an inner cavity for accommodating the motor (20). It is characterized in that The stator (21) is directly fixed in the inner cavity of the housing (10) in a manner of contacting the inner wall of the housing (10).

2. The shift actuator according to claim 1, characterized in that: The shift actuator comprises a control unit (50) for controlling the motor (20); the inner cavity of the housing (10) comprises an open end in the axial direction; the motor (20) can be installed in the housing (10) from the open end; the axial end of the motor shaft (23) facing away from the open end is transmission-connected to the ball screw (30); the control unit (50) is installed at the open end so as to encapsulate the motor (20) in the housing (10).

3. The shift actuator according to claim 2, characterized in that: The shift actuator comprises a position sensor (60) for detecting the rotational position of the motor (20), wherein the position sensor (60) is mounted on an axial end portion of the motor shaft (23) facing the open end.

4. The shift actuator according to claim 3, characterized in that: The shift actuator comprises a retaining sleeve (70) fixed to an axial end portion of the motor shaft (23) facing the open end, and the position sensor (60) is fixed to the motor shaft (23) via the retaining sleeve (70).

5. The shift actuator according to any one of claims 2 to 4, characterized in that: The shift actuator comprises a bearing (80) which is mounted on a portion of the motor shaft (23) extending out of the rotor (22) in the axial direction away from the open end. The motor shaft (23) is supported in the inner cavity of the housing (10) through the bearing (80).

6. The shift actuator according to claim 5, characterized in that: The motor shaft (23) includes a flange (23a), the inner ring of the bearing (80) and the rotor (22) abut against opposite sides of the flange (23a) in the axial direction, and the outer ring of the bearing (80) abuts against the housing (10) in the axial direction away from the flange (23a).

7. A method for assembling a shift actuator according to claim 6, characterized in that: The assembly method comprises: Installing the stator (21) in the housing (10); Assembling the rotor (22), the motor shaft (23), the position sensor (60) and the bearing (80) into a subassembly; installing the subassembly onto the radial inner side of the stator (21); and The control unit (50) is mounted on the housing (10).

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