Reaction force actuator

Abstract

A reaction force actuator includes: a torque sensor (5); a speed reducer (7); a reaction force controller (6b); and a housing (40) configured to house the torque sensor (5), an reaction force motor (4), the reaction force controller (6b), and the speed reducer (7), the housing (40) includes a gear housing (50) configured to house the speed reducer (7) and the torque sensor (5), a motor housing (60) connected to the gear housing (50) and configured to house the reaction force motor (4), and a control housing (70) connected to the motor housing (60) and configured to house the reaction force controller (6b), the control housing (70) extends in a radial direction of the motor housing (60), and the control housing (70) is provided with a connector (85), to which the cable (36) is connected, side by side with the motor housing (60).

Description

REACTION FORCE ACTUATOR

[0001] The present invention relates to a reaction force actuator.

[0002] WO 2020 / 137568 discloses an electric power steering device including a steering wheel and an electric drive device. The electric drive device assists a torque when the steering wheel is rotated, and includes a torque sensor, an electric motor unit, and an ECU. The ECU is provided at a tip end portion of a cylindrical motor housing that houses a motor unit.

[0003] In the electric drive device described in WO 2020 / 137568, a connector for electrically connecting the torque sensor and the ECU via a cable is provided at the tip end portion of the motor housing. Therefore, the electric drive device in an axial direction of the motor housing may become large.

[0004] An object of the present invention is to downsize a reaction force actuator.

[0005] According to one aspect of the present invention, a reaction force actuator includes: an input shaft configured to allow a steering torque to be input; a reaction force shaft connected to the input shaft via a torsion bar; a torque sensor configured to detect the steering torque; an electric motor configured to generate a reaction force against the steering torque and input the reaction force to the reaction force shaft; a speed reducer configured to transmit a driving force of the electric motor to the reaction force shaft; a control unit electrically connected to the torque sensor by a cable and configured to control the electric motor based on a detection result of the torque sensor; and a housing configured to house the torque sensor, the electric motor, the control unit, and the speed reducer, the housing includes a gear housing configured to house the speed reducer and the torque sensor, a motor housing connected to the gear housing and configured to house the electric motor, and a control housing connected to the motor housing and configured to house the control unit, the control housing extends in a radial direction of the motor housing, and the control housing is provided with a connector, to which the cable is connected, side by side with the motor housing.

[0006] FIG. 1 is a configuration diagram of an electric power steering device according to an embodiment of the present invention.FIG. 2 is a perspective view of a reaction force actuator according to the embodiment of the present invention.FIG. 3 is a sectional view of the reaction force actuator according to the embodiment of the present invention.FIG. 4 is a sectional view of the reaction force actuator according to the embodiment of the present invention.FIG. 5 is a plan view of a reaction force actuator according to the embodiment of the present invention.FIG. 6 is a sectional view of a reaction force actuator according to a modification of the embodiment of the present invention, which corresponds to FIG. 4.

[0007] Hereinafter, a reaction force actuator 100 according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the reaction force actuator 100 is provided in an electric power steering device 1 as a steering device.

[0008] The electric power steering device 1 shown in FIG. 1 performs a steer-by-wire control in which turning of wheels 3 is controlled in accordance with an operation of a steering wheel 2 by a driver. In the electric power steering device 1, the steering wheel 2 operated by the driver and the wheels 3 are mechanically separated.

[0009] As shown in FIG. 1, the electric power steering device 1 includes a steering shaft 10 connected to the steering wheel 2 and configured to rotate in accordance with the rotation of the steering wheel 2, a steering angle sensor 14 provided on an input shaft 11 of the steering shaft 10 and configured to detect a rotation angle of the steering wheel 2, a rack shaft 20 configured to turn the wheels 3, an electric motor 8 configured to displace the rack shaft 20, and a turning controller 6a configured to control driving of the electric motor 8.

[0010] The steering shaft 10 includes the input shaft 11 that rotates by an input of a steering torque by a steering operation in which a driver operates the steering wheel 2, a reaction force shaft 12 to which a reaction force is input from a reaction force motor 4 as described later, and a torsion bar 13 that connects the input shaft 11 and the reaction force shaft 12.

[0011] The rack shaft 20 is a shaft-like member provided to extend in a left-right direction of a vehicle, is connected to one wheel of the wheels 3 via a first tie rod 21a and a first knuckle arm 22a, and is connected to the other wheel of the wheels 3 via a second tie rod 21b and a second knuckle arm 22b.

[0012] The first and second tie rods 21a and 21b are swingably connected to the rack shaft 20 via first and second ball joints 23a and 23b as connection portions provided at both end portions of the rack shaft 20.

[0013] The turning controller 6a is implemented by a microcomputer including a central processing unit (CPU) that performs arithmetic processing, a read-only memory (ROM) that stores a control program and the like executed by the CPU, and a random access memory (RAM) that stores an arithmetic result and the like of the CPU. The turning controller 6a may be implemented by a single microcomputer or a plurality of microcomputers. In addition to a detection signal of the steering angle sensor 14, vehicle state information such as a vehicle speed is input to the turning controller 6a from a sensor or a controller mounted on the vehicle.

[0014] The steering angle sensor 14 calculates a rotation angle of the input shaft 11 and outputs a signal corresponding to the rotation angle to the turning controller 6a. The turning controller 6a controls the electric motor 8 according to an operation state of the steering wheel 2 to turn the wheels 3. A torque of the electric motor 8 is transmitted to an output shaft 15 via a speed reducer 9.

[0015] The output shaft 15 and the rack shaft 20 are connected to each other via a rack-and-pinion mechanism including a pinion gear 15a provided at an end portion of the output shaft 15 and a rack gear 20a provided on the rack shaft 20. The pinion gear 15a and the rack gear 20a mesh with each other, and a torque of the output shaft 15 is converted into a load in an axial direction of the rack shaft 20 via the pinion gear 15a and the rack gear 20a and transmitted to the rack shaft 20. Accordingly, the rack shaft 20 is displaced in the axial direction by the transmitted torque, and turns the wheels 3 via the first and second tie rods 21a and 21b.

[0016] In the electric power steering device 1 having the above configuration, the turning controller 6a sets a target turning angle based on a detection result of the steering angle sensor 14 and the vehicle speed, and controls the driving of the electric motor 8 such that a turning angle of the wheels 3 matches the target turning angle. Accordingly, the wheels 3 are turned.

[0017] The electric power steering device 1 includes the reaction force actuator 100 that applies a reaction force against the steering torque to the steering wheel 2. The reaction force actuator 100 can give a pseudo weight of the steering wheel to the steering operation of the driver.

[0018] The reaction force actuator 100 includes the input shaft 11 to which the steering torque is input, the reaction force shaft 12 connected to the input shaft 11 via the torsion bar 13, a torque sensor 5 that detects the steering torque, the reaction force motor 4 as an electric motor that generates a reaction force against the steering torque and inputs the reaction force to the reaction force shaft 12, a speed reducer 7 that transmits a driving force of the reaction force motor 4 to the reaction force shaft 12, a reaction force controller 6b as a control unit that is electrically connected to the torque sensor 5 by a cable 36, and a housing 40 (see FIG. 2) that houses the torque sensor 5, the reaction force motor 4, the reaction force controller 6b, and the speed reducer 7.

[0019] As shown in FIG. 3, the input shaft 11, the torsion bar 13, and the reaction force shaft 12 are provided coaxially. The torque sensor 5 is attached across the input shaft 11 and the reaction force shaft 12, and detects steering torque applied to the torsion bar 13 based on a rotation angle difference between the input shaft 11 and the reaction force shaft 12. Since a well-known configuration can be adopted as the configuration of the torque sensor 5, detailed descriptions and showing are omitted. A substrate (not shown) of the torque sensor 5 and the reaction force controller 6b are electrically connected via the cable 36 as a signal line, power is supplied from the reaction force controller 6b to the torque sensor 5 through the cable 36, and a steering torque signal detected by the torque sensor 5 is output to the reaction force controller 6b. Similarly to the turning controller 6a, the reaction force controller 6b is implemented by a microcomputer including a CPU, a ROM, and a RAM.

[0020] As shown in FIGS. 3 and 4, the speed reducer 7 includes a worm shaft 7a connected to an output shaft 4a (see FIG. 4) of the reaction force motor 4, and a worm wheel 7b (see FIG. 3) meshing with the worm shaft and fixed to the reaction force shaft 12. The worm shaft 7a is provided coaxially with the output shaft 4a of the reaction force motor 4, and is provided perpendicular to the axial direction of the input shaft 11, the torsion bar 13, and the reaction force shaft 12. The worm wheel 7b is provided on an outer peripheral surface of the reaction force shaft 12. A rotational torque of the output shaft 4a of the reaction force motor 4 is transmitted to the reaction force shaft 12 through the worm shaft 7a and the worm wheel 7b.

[0021] The reaction force controller 6b controls the reaction force motor 4. Specifically, the reaction force controller 6b calculates the reaction torque output from the reaction force motor 4 based on the detection result of the torque sensor 5, and controls the driving of the reaction force motor 4 such that the reaction torque is generated. The reaction torque of the reaction force motor 4 is transmitted to the reaction force shaft 12 through the speed reducer 7.

[0022] As shown in FIGS. 2 to 4, the housing 40 includes a gear housing 50 that houses the speed reducer 7 and the torque sensor 5, a cylindrical motor housing 60 that is connected to the gear housing 50 and houses the reaction force motor 4, and a control housing 70 (see FIGS. 2 and 4) that is connected to the motor housing 60 and houses the reaction force controller 6b. In the present embodiment, the gear housing 50, the motor housing 60, and the control housing 70 are formed separately. That is, the gear housing 50, the motor housing 60, and the control housing 70 are configured as separate components. In FIG. 2, in order to show the housing 40, showing of the cable 36 is omitted.

[0023] The gear housing 50 is formed in a substantially cylindrical shape, and houses a part of the input shaft 11, the torsion bar 13, and the reaction force shaft 12, the torque sensor 5, and the worm shaft 7a and the worm wheel 7b of the speed reducer 7. As shown in FIG. 3, the gear housing 50 has opening portions 51 and 52 at both end portions in the axial direction, a first cover 53 is provided to the opening portion 51 through which the input shaft 11 and the torsion bar 13 are inserted, and a second cover 54 is provided to the opening portion 52 through which the reaction force shaft 12 is inserted. The input shaft 11 and the torsion bar 13 are inserted through the first cover 53, and an end portion of the reaction force shaft 12 is housed in the second cover 54. A bearing 92 that rotatably supports the input shaft 11 is housed in the first cover 53, and the first cover 53 is connected to the gear housing 50 by a bolt 18. The gear housing 50 houses a bearing 93 that rotatably supports the reaction force shaft 12. A through hole (not shown) is formed in a side surface of the gear housing 50 to face the torque sensor 5, and the cable 36 is inserted into the through hole and connected to the torque sensor 5 in the gear housing 50. A position where the cable 36 is provided in a circumferential direction of the gear housing 50 is not limited to the position shown in FIGS. 2 to 5.

[0024] As shown in FIG. 4, the gear housing 50 has an opening portion 57 that opens in the side surface of the gear housing 50 and communicates with a housing hole 56 in which the worm shaft 7a is housed. The opening portion 57 is formed coaxially with the worm shaft 7a, that is, perpendicular to the axial direction of the input shaft 11, the torsion bar 13, and the reaction force shaft 12. The motor housing 60 is connected to an end surface of the opening portion 57 via a connection member 19 such as a bolt.

[0025] As shown in FIG. 4, the motor housing 60 is provided to extend coaxially with the opening portion 57 of the gear housing 50, the worm shaft 7a, and the output shaft 4a of the reaction force motor 4. The motor housing 60 houses the output shaft 4a of the reaction force motor 4, a motor core (not shown), and the like. In FIG. 4, components of the reaction force motor 4 other than the output shaft 4a are not shown. The motor housing 60 has one end surface 61 connected to the gear housing 50 and the other end surface 62 connected to the control housing 70 via a connection member 80.

[0026] As shown in FIG. 4, the control housing 70 is provided to cover an opening portion 63 formed in the end surface 62 of the motor housing 60. Although not shown in FIG. 4, the control housing 70 houses the reaction force controller 6b, a substrate thereof, and the like. As described above, the reaction force actuator 100 of the present embodiment is an electromechanical integrated type in which the reaction force motor 4 and the reaction force controller 6b as a control unit of the reaction force motor 4 are integrally provided.

[0027] As shown in FIGS. 2 and 5, the control housing 70 extends in a radial direction of the motor housing 60 and has a substantially rectangular parallelepiped shape elongated in one direction. Specifically, the control housing 70 is formed to extend in an extending direction that is a direction perpendicular to both the axial direction of the input shaft 11, the torsion bar 13, and the reaction force shaft 12 and the axial direction of the output shaft 4a and the worm shaft 7a of the reaction force motor 4. The control housing 70 and the gear housing 50 face each other with a space A therebetween, which is a dead space. The control housing 70 is provided with a connector 85, to which the cable 36 is connected, side by side with the motor housing 60 in the extending direction. Specifically, the connector 85 is provided on a side opposite to the worm shaft 7a with respect to the input shaft 11, and an opening portion into which the cable 36 is inserted is provided in the space A to face the gear housing 50. In other words, the connector 85 is provided such that at least a part of the gear housing 50 is present on an extension line of the opening portion.

[0028] Accordingly, in the reaction force actuator 100 of the present embodiment, the control housing 70 extending in the radial direction of the motor housing 60 is provided with the connector 85 side by side with the motor housing 60. Therefore, a dimension of the reaction force actuator 100 in the axial direction of the motor housing 60 can be reduced by an amount of the connector 85 as compared with a case where the connector 85 is provided on a tip end side of the housing 40 (a side, opposite to the motor housing 60, of the control housing 70). Therefore, the reaction force actuator 100 can be downsized.

[0029] In the reaction force actuator 100 of the present embodiment, the gear housing 50, the motor housing 60, and the control housing 70 are formed separately. Therefore, when specifications of some components of the reaction force actuator 100 are changed, for example, when a specification of the reaction force motor 4 is changed, only the housing that houses the some components may be changed, and it is unnecessary to change all the housings. Therefore, it is possible to cope with the reaction force actuator 100 having various specifications at a low cost.

[0030] In the reaction force actuator 100 of the present embodiment, the connector 85 is provided in the space A that is a dead space formed between the gear housing 50 and the control housing 70. Therefore, since the connector 85 is provided at a position where the reaction force actuator 100 does not become large by using the dead space, the reaction force actuator 100 can be downsized.

[0031] According to the present embodiment described above, the following effects are achieved.

[0032] In the reaction force actuator 100, the control housing 70 extending in the radial direction of the motor housing 60 is provided with the connector 85 side by side with the motor housing 60. Therefore, since the dimension of the reaction force actuator 100 in the axial direction of the motor housing 60 can be reduced, the reaction force actuator 100 can be downsized.

[0033] Next, modifications of the present embodiment will be described. The following modifications are also within the scope of the present invention, and it is also possible to combine the following modifications and the configurations of the above embodiment, or to combine the following modifications.

[0034] <Modification 1> In the above embodiment, the control housing 70 is formed to extend in the extending direction that is the direction perpendicular to both the axial direction of the input shaft 11, the torsion bar 13, and the reaction force shaft 12 and the axial direction of the output shaft 4a and the worm shaft 7a of the reaction force motor 4. The present invention is not limited to this, and as shown in FIG. 6, the control housing 70 may extend along the input shaft 11. In other words, the direction in which the control housing 70 extends may be shifted by 90 degrees. In this configuration, the control housing 70 and the gear housing 50 also face each other with a space therebetween. The connector 85 is provided in the above space to face the input shaft 11. In other words, the connector 85 is provided such that at least a part of the input shaft 11 is present on the extension line of the opening portion. In this configuration, similarly to the above embodiment, since the connector 85 is provided in the dead space formed between the gear housing 50 and the control housing 70, the reaction force actuator 100 also can be downsized using the dead space.

[0035] <Modification 2> In the above embodiment, the gear housing 50, the motor housing 60, and the control housing 70 are formed separately. The present invention is not limited to this, and the gear housing 50, the motor housing 60, and the control housing 70 may be integrally formed from a viewpoint of reducing the number of components. That is, the gear housing 50, the motor housing 60, and the control housing 70 may be formed as one component.

[0036] Hereinafter, configurations, operations, and effects of the embodiment of the present invention will be collectively described.

[0037] The reaction force actuator 100 includes the input shaft 11 to which the steering torque is input, the reaction force shaft 12 connected to the input shaft 11 via the torsion bar 13, the torque sensor 5 that detects the steering torque, the reaction force motor 4 as an electric motor that generates the reaction force against the steering torque and inputs the reaction force to the reaction force shaft 12, the speed reducer 7 that transmits the driving force of the reaction force motor 4 to the reaction force shaft 12, the reaction force controller 6b as a control unit that is electrically connected to the torque sensor 5 by the cable 36 and controls the reaction force motor 4 based on the detection result of the torque sensor 5, and the housing 40 that houses the torque sensor 5, the reaction force motor 4, the reaction force controller 6b, and the speed reducer 7. The housing 40 includes the gear housing 50 that houses the speed reducer 7 and the torque sensor 5, the motor housing 60 that is connected to the gear housing 50 and houses the reaction force motor 4, and the control housing 70 that is connected to the motor housing 60 and houses the reaction force controller 6b. The control housing 70 extends in the radial direction of the motor housing 60, and the control housing 70 is provided with the connector 85, to which the cable 36 is connected, side by side with the motor housing 60.

[0038] In this configuration, the control housing 70 extending in the radial direction of the motor housing 60 is provided with the connector 85 side by side with the motor housing 60. Therefore, since the dimension of the reaction force actuator 100 in the axial direction of the motor housing 60 can be reduced, the reaction force actuator 100 can be downsized.

[0039] In the reaction force actuator 100, the gear housing 50, the motor housing 60, and the control housing 70 are formed separately.

[0040] In this configuration, since the three housings 40 are formed separately, when specifications of some components of the reaction force actuator 100 are changed, it is only necessary to change the housing 40 that houses the some components, and it is unnecessary to change all the housings 40. Therefore, it is possible to cope with the reaction force actuator 100 having various specifications at a low cost.

[0041] In the reaction force actuator 100, the speed reducer 7 includes the worm shaft connected to the output shaft of the reaction force motor 4 and the worm wheel meshing with the worm shaft and fixed to the reaction force shaft 12, and the connector 85 is provided on the side opposite to the worm shaft with respect to the input shaft 11.

[0042] In the reaction force actuator 100, the control housing 70 extends along the input shaft 11, and the connector 85 is provided to face the input shaft 11.

[0043] In these configurations, the connector 85 is provided in the dead space formed between the gear housing 50 and the control housing 70. Therefore, the reaction force actuator 100 can be downsized.

[0044] Embodiments of the present invention were described above, but the above embodiments are merely examples of applications of the present invention, and the technical scope of the present invention is not limited to the specific constitutions of the above embodiments.

[0045] The torque sensor 5 may have a function of an angle sensor that detects an absolute rotation angle of the input shaft 11.

[0046] The gear housing 50 and the first cover 53 may be integrally formed.

[0047] With respect to the above description, the contents of application No. 2024-28213, with a filing date of February 28, 2024 in Japan, are incorporated herein by reference.

Claims

1. A reaction force actuator comprising: an input shaft configured to allow a steering torque to be input; a reaction force shaft connected to the input shaft via a torsion bar; a torque sensor configured to detect the steering torque; an electric motor configured to generate a reaction force against the steering torque and input the reaction force to the reaction force shaft; a speed reducer configured to transmit a driving force of the electric motor to the reaction force shaft; a control unit electrically connected to the torque sensor by a cable and configured to control the electric motor based on a detection result of the torque sensor; and a housing configured to house the torque sensor, the electric motor, the control unit, and the speed reducer, wherein the housing includes a gear housing configured to house the speed reducer and the torque sensor, a motor housing connected to the gear housing and configured to house the electric motor, and a control housing connected to the motor housing and configured to house the control unit, the control housing extends in a radial direction of the motor housing, and the control housing is provided with a connector, to which the cable is connected, side by side with the motor housing.

2. The reaction force actuator according to claim 1, wherein the gear housing, the motor housing, and the control housing are formed separately from each other.

3. The reaction force actuator according to claim 1, wherein the speed reducer includes a worm shaft connected to an output shaft of the electric motor, and a worm wheel meshing with the worm shaft and fixed to the reaction force shaft, and the connector is provided on a side opposite to the worm shaft with respect to the input shaft.

4. The reaction force actuator according to claim 1, wherein the control housing extends along the input shaft, and the connector is provided to face the input shaft.

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