WO2025192138A1 - Reaction force actuator - Google Patents

Reaction force actuator

Info

Publication number
WO2025192138A1
WO2025192138A1 PCT/JP2025/004547 JP2025004547W WO2025192138A1 WO 2025192138 A1 WO2025192138 A1 WO 2025192138A1 JP 2025004547 W JP2025004547 W JP 2025004547W WO 2025192138 A1 WO2025192138 A1 WO 2025192138A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensor
reaction force
input shaft
diameter portion
shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/004547
Other languages
French (fr)
Inventor
Yuichi Doki
Takaya Yagyu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ree Automotive Ltd
KYB Corp
Original Assignee
Softwheel Ltd
KYB Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Softwheel Ltd, KYB Corp filed Critical Softwheel Ltd
Publication of WO2025192138A1 publication Critical patent/WO2025192138A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/001—Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup
    • B62D5/005—Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup means for generating torque on steering wheel or input member, e.g. feedback
    • B62D5/006—Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup means for generating torque on steering wheel or input member, e.g. feedback power actuated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/08—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to driver input torque
    • B62D6/10—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to driver input torque characterised by means for sensing or determining torque

Definitions

  • the present invention relates to a reaction force actuator.
  • JP 2018-43731A discloses a steer-by-wire steering device.
  • a turning device includes a steering shaft connected to a steering wheel, an angle sensor provided on the steering shaft and configured to detect a rotation angle of the steering shaft, a turning motor configured to generate a steering torque based on a detection result of the angle sensor, and a reaction force motor configured to generate a steering reaction force in the steering wheel.
  • An object of the present invention is to improve ease of attachability of a sensor provided in a reaction force actuator.
  • a reaction force actuator provided in a steering device, the reaction force actuator includes: an input shaft configured to allow a steering torque to be input through a steering wheel; a reaction force shaft connected to the input shaft via a torsion bar; a first sensor and a second sensor configured to detect a rotation angle of the input shaft to control the steering device and having a same configuration; and an electric motor configured to generate a reaction force against the steering torque and input the reaction force to the reaction force shaft, the input shaft includes a large-diameter portion formed on a reaction force shaft side, and a small-diameter portion formed on a steering wheel side with respect to the large-diameter portion, a collar including a main body portion having an outer diameter same as the large-diameter portion is provided on an outer peripheral surface of the small-diameter portion, the first sensor is directly provided on an outer peripheral surface of the large-diameter portion of the input shaft, and the second sensor is provided on the outer peripheral surface of the small-di
  • FIG. 1 is a configuration diagram of an electric power steering device according to an embodiment of the present invention.
  • FIG. 2 is a sectional view of the reaction force actuator according to the embodiment of the present invention.
  • reaction force actuator 100 is provided in an electric power steering device 1 as a steering device.
  • 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.
  • the steering wheel 2 operated by the driver and the wheels 3 are mechanically separated.
  • 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 first sensor 61 and a second sensor 71 provided on an input shaft 11 of the steering shaft 10 and configured to detect a rotation angle of the input shaft 11 to control the electric power steering device 1, 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.
  • 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.
  • 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.
  • 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.
  • the first sensor 61 and the second sensor 71 have the same configuration. However, in the present embodiment, the first sensor 61 and the second sensor 71 have different functions.
  • the first sensor 61 functions as a torque angle sensor that detects the rotation angle of the input shaft 11 and the steering torque input to the input shaft 11.
  • the second sensor 71 functions as an angle sensor that detects only the rotation angle of the input shaft 11.
  • the first sensor 61 outputs a detection result of the rotation angle (specifically, a signal corresponding to the detection result) to the turning controller 6a through a cable, and outputs a detection result of the steering torque to the reaction force controller 6b described later.
  • the second sensor 71 outputs the detection result of the rotation angle to the turning controller 6a through the cable. Details of the first sensor 61 and the second sensor 71 will be described later.
  • 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.
  • 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.
  • the turning controller 6a controls the electric motor 8 according to an operation state of the steering wheel 2 to turn the wheels 3. Specifically, the turning controller 6a sets a target turning angle based on the rotation angle of the input shaft 11 (steering wheel 2) output from the first sensor 61 and the second sensor 71 and the vehicle state information such as 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 steering of the electric power steering device 1 is controlled. The rotation angle output from one of the first sensor 61 and the second sensor 71 is used to set the target turning angle.
  • the rotation angle output from the other sensor is used.
  • the steering device 1 in which the steer-by-wire control is performed, if only one sensor for detecting the rotation angle of the input shaft 11 is provided, the steering may become impossible if the sensor fails. Therefore, in the present embodiment, in order to improve safety, two sensors (first sensor 61 and second sensor 71) are provided for redundancy. A torque of the electric motor 8 is transmitted to an output shaft 15 via a speed reducer 9.
  • 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.
  • the reaction force actuator 100 can give a pseudo weight of the steering wheel to the steering operation of the driver.
  • the reaction force actuator 100 includes the input shaft 11 to which the steering torque is input via the steering wheel 2, the reaction force shaft 12 connected to the input shaft 11 via the torsion bar 13, the first sensor 61 and the second sensor 71 for controlling the electric power steering device 1, 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, and a reaction force controller 6b as a control unit that is electrically connected to the first sensor 61 and the second sensor 71 via a cable.
  • the input shaft 11 includes a large-diameter portion 11a formed on a reaction force shaft 12 side, a small-diameter portion 11b formed on a steering wheel 2 side with respect to the large-diameter portion 11a, and an insertion portion 11c inserted into the reaction force shaft 12.
  • the large-diameter portion 11a has a diameter larger than that of the small-diameter portion 11b.
  • the small-diameter portion 11b is formed to extend between the large-diameter portion 11a and one end portion (end portion on upper side in FIG. 2) of the input shaft 11.
  • a step portion 11d is formed between the large-diameter portion 11a and the small-diameter portion 11b.
  • a cylindrical collar 80 is provided on an outer peripheral surface of the small-diameter portion 11b. Details of the collar 80 will be described later.
  • the first sensor 61 is directly provided on the large-diameter portion 11a of the input shaft 11 without a collar or the like interposed therebetween.
  • An inner diameter of an insertion hole 61a of the first sensor 61 through which the input shaft 11 is inserted is substantially the same as an outer diameter of the large-diameter portion 11a of the input shaft 11.
  • the first sensor 61 detects the rotation angle of the input shaft 11 and a steering torque applied to the torsion bar 13.
  • a method for detecting the rotation angle of the input shaft 11 is a well-known technique, for example, a center gear (not shown) that rotates integrally with the input shaft 11 and two outer gears (not shown) that mesh with the center gear are used to detect a rotation angle of the center gear, that is, the rotation angle of the input shaft 11, based on a change in magnetic flux that accompanies the rotation of the two outer gears.
  • a first rotor 61b that rotates integrally with the input shaft 11 and a second rotor 61c that rotates integrally with the reaction force shaft 12 are used, a change in a magnetic field due to a rotation angle difference between the input shaft 11 and the reaction force shaft 12 is detected by a detection coil pattern of a substrate (not shown), and the steering torque is detected.
  • the second sensor 71 is provided on the small-diameter portion 11b of the input shaft 11 via the collar 80. Since the second sensor 71 has the same configuration as the first sensor 61, components corresponding to those of the first sensor 61 are denoted by corresponding reference numerals. As described above, the second sensor 71 functions as an angle sensor that detects only the rotation angle of the input shaft 11 without detecting the steering torque input to the input shaft 11. Specifically, in the second sensor 71, since both a first rotor 71b corresponding to the first rotor 61b and a second rotor 71c corresponding to the second rotor 61c rotate integrally with the collar 80 (input shaft 11), the rotation angle of the input shaft 11 can be detected, but the steering torque cannot be detected.
  • the reaction force controller 6b is implemented by a microcomputer including a CPU, a ROM, and a RAM.
  • the speed reducer 7 includes a worm shaft 7a connected to an output shaft (not shown) of the reaction force motor 4, and a worm wheel 7b meshing with the worm shaft 7a and fixed to the reaction force shaft 12. A rotational torque of the output shaft of the reaction force motor 4 is transmitted to the reaction force shaft 12 through the worm shaft 7a and the worm wheel 7b.
  • 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.
  • the reaction force actuator 100 further includes a first housing 40 that houses the first sensor 61, a second housing 50 that houses the second sensor 71, a first cover 53 that seals an opening portion 51 of the second housing 50, and a motor housing (not shown) that houses the reaction force motor 4 and the reaction force controller 6b.
  • the first housing 40 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 first sensor 61, and the worm shaft 7a and the worm wheel 7b of the speed reducer 7.
  • the first housing 40 has opening portions 41 and 42 at both end portions in the axial direction, the second housing 50 is provided to the opening portion 41 through which the input shaft 11 and the torsion bar 13 are inserted, and a second cover 54 is provided to the opening portion 42 through which the reaction force shaft 12 is inserted.
  • the second cover 54 houses the end portion of the reaction force shaft 12.
  • the first housing 40 houses a bearing 93 that rotatably supports the reaction force shaft 12.
  • a motor housing is connected to the first housing 40 via a bolt or the like (not shown).
  • the second housing 50 is formed in a substantially cylindrical shape, and houses the second sensor 71 and a part of the input shaft 11, the torsion bar 13, and the collar 80.
  • the second housing 50 is formed in substantially the same configuration as a portion of the first housing 40 that houses the first sensor 61.
  • the second housing 50 has opening portions 51 and 52 at both end portions in the axial direction, the first cover 53 is provided to the opening portion 51 on the steering wheel 2 side (upper side in FIG. 2), and the first housing 40 is provided to the opening portion 52 on the reaction force shaft 12 side. Accordingly, the second housing 50 is formed separately from the first housing 40 and is sandwiched between the first housing 40 and the first cover 53.
  • the input shaft 11 and the torsion bar 13 are inserted into the first cover 53, and a bearing 92 that rotatably supports the input shaft 11 is housed in the first cover 53.
  • Bolts 18 are provided on the first cover 53 across the first housing 40 and the second housing 50, and the first cover 53, the first housing 40, and the second housing 50 are fixed to each other by the bolts 18.
  • O-rings 85 and 86 are provided as sealing members that are compressed in a radial direction.
  • the O-rings 85 and 86 perform the sealing between the first housing 40 and the second housing 50 and between the first cover 53 and the second housing 50.
  • the O-ring 85 is provided to be compressed in the radial direction, the first housing 40 is aligned with respect to the second housing 50 by the O-ring 85.
  • the second housing 50 is aligned with respect to the first cover 53 by the O-ring 86.
  • the collar 80 is for providing the second sensor 71 on the small-diameter portion 11b of the input shaft 11.
  • the collar 80 increases an outer diameter of the small-diameter portion 11b in order to attach the second sensor 71, which is not fitted to the small-diameter portion 11b as it is, to the small-diameter portion 11b.
  • the collar 80 includes a main body portion 80a having an outer diameter same as that of the large-diameter portion 11a of the input shaft 11 and provided with the second sensor 71, a thick portion 80b having a diameter larger than that of the main body portion 80a, a thin portion 80c formed at one end portion in the axial direction (axial direction of collar 80 and input shaft 11), and a welded portion 80d formed at the other end portion in the axial direction and welded to the input shaft 11.
  • the collar 80 is formed with a uniform inner diameter throughout and has substantially the same outer diameter as the small-diameter portion 11b of the input shaft 11.
  • the main body portion 80a has substantially the same outer diameter as the insertion hole 71a of the second sensor 71.
  • the thick portion 80b has a diameter largest in the collar 80, and a lower end portion of the second sensor 71 abuts an end surface of the thick portion 80b. That is, the thick portion 80b positions the second sensor 71 with respect to the collar 80.
  • the thin portion 80c is provided at one end portion of the collar 80 in the axial direction to be continuous with the thick portion 80b, and has a tip end portion abutting the step portion 11d of the input shaft 11. Accordingly, the collar 80 is positioned with respect to the input shaft 11.
  • one end portion of the collar 80 in the axial direction abuts the step portion 11d of the input shaft 11, and the second sensor 71 is positioned with respect to the input shaft 11 via the collar 80.
  • the thin portion 80c is not an essential component, and the thick portion 80b may abut the step portion 11d of the input shaft 11 without forming the thin portion 80c.
  • the welded portion 80d is provided at the other end portion of the collar 80 in the axial direction to be continuous with the main body portion 80a, and is welded to the input shaft 11 by, for example, laser welding.
  • the collar 80 is not attached to the input shaft 11 when the first sensor 61 is attached. After the first sensor 61 is attached, the welded portion 80d is welded to the input shaft 11 while the tip end portion of the thin portion 80c abuts the step portion 11d, so that the collar 80 is positioned and fixed to an outer peripheral surface of the input shaft 11.
  • the reaction force actuator 100 of the present embodiment since two sensors are provided, an insertion distance of the first sensor 61 to the input shaft 11 is long. However, the first sensor 61 is attached to the input shaft 11 while the collar 80 is not provided on the small-diameter portion 11b of the input shaft 11. Therefore, the first sensor 61 can be easily attached to the large-diameter portion 11a of the input shaft 11 through the small-diameter portion 11b.
  • the second sensor 71 can be attached to the small-diameter portion 11b of the input shaft 11 via the collar 80 by providing the collar 80 on the small-diameter portion 11b after the first sensor 61 is attached. Accordingly, the first sensor 61 and the second sensor 71 having the same configuration can be easily attached to the input shaft 11.
  • the configuration of the input shaft 11 having the large-diameter portion 11a and the small-diameter portion 11b in the present embodiment can also be included in a reaction force actuator in the related art in which only one non-redundant sensor is provided. Therefore, it is possible to easily make redundant only by adding the collar 80, the second sensor 71, and the second housing 50 to the reaction force actuator in the related art.
  • the reaction force actuator 100 can be made redundant only by stacking the second housing 50 that houses the second sensor 71 on the first housing 40.
  • the first sensor 61 can be easily attached to the large-diameter portion 11a of the input shaft 11 through the small-diameter portion 11b.
  • the second sensor 71 can be attached to the small-diameter portion 11b of the input shaft 11 via the collar 80 by providing the collar 80 on the small-diameter portion 11b after the first sensor 61 is attached. Accordingly, the first sensor 61 and the second sensor 71 having the same configuration can be easily attached to the input shaft 11, and thus, attachability of the first sensor 61 and the second sensor 71 is improved.
  • the reaction force actuator 100 provided in the electric power steering device 1 as a steering device includes: the input shaft 11 to which the steering torque is input via the steering wheel 2; the reaction force shaft 12 connected to the input shaft 11 via the torsion bar 13; the first sensor 61 and the second sensor 71 that detect the rotation angle of the input shaft 11 to control the electric power steering device 1 and have the same configuration as each other; and 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, in which the input shaft 11 includes the large-diameter portion 11a formed on the reaction force shaft 12 side and the small-diameter portion 11b formed on the steering wheel 2 side with respect to the large-diameter portion 11a, the collar 80 including the main body portion 80a having the same outer diameter as the large-diameter portion 11a is provided on the outer peripheral surface of the small-diameter portion 11b, the first sensor 61 is provided directly on an outer peripheral surface of the large-diameter portion 11a of the
  • the first sensor 61 can be easily attached to the large-diameter portion 11a of the input shaft 11 through the small-diameter portion 11b before the collar 80 is provided on the input shaft 11.
  • the second sensor 71 can be attached to the small-diameter portion 11b of the input shaft 11 via the collar 80 by providing the collar 80 on the small-diameter portion 11b after the first sensor 61 is attached. Accordingly, the first sensor 61 and the second sensor 71 having the same configuration can be easily attached to the input shaft 11. The attachability of the first sensor 61 and the second sensor 71 is improved.
  • one end portion of the collar 80 in the axial direction abuts the step portion 11d formed between the large-diameter portion 11a and the small-diameter portion 11b of the input shaft 11.
  • the second sensor 71 can be positioned with respect to the input shaft 11 via the collar 80.
  • the reaction force actuator 100 further includes the first housing 40 that houses the first sensor 61 and the second housing 50 that houses the second sensor 71, and the first housing 40 and the second housing 50 are formed separately.
  • reaction force actuator 100 can be made redundant only by stacking the second housing 50 that houses the second sensor 71 on the first housing 40.
  • the O-ring 85 as a sealing member compressed in the radial direction is provided between the first housing 40 and the second housing 50.
  • the second housing 50 can be aligned with respect to the first housing 40 while the O-ring 85 performs the sealing between the first housing 40 and the second housing 50.
  • the second sensor 71 may have a function of a torque angle sensor that detects both the rotation angle of the input shaft 11 and the steering torque.
  • the second housing 50 and the first cover 53 may be integrally formed.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Steering Mechanism (AREA)

Abstract

A reaction force actuator (100) includes: an input shaft (11); a reaction force shaft (12); and a first sensor (61) and a second sensor (71) configured to detect a rotation angle of the input shaft (11) and having a same configuration, the input shaft (11) includes a large-diameter portion (11a) formed on a reaction force shaft (12) side, and a small-diameter portion (11b) formed on a steering wheel (2) side with respect to the large-diameter portion (11a), a collar (80) including a main body portion (80a) having an outer diameter same as the large-diameter portion (80a) is provided on an outer peripheral surface of the small-diameter portion (11b), the first sensor (61) is directly provided on an outer peripheral surface of the large-diameter portion (11a) of the input shaft (11), and the second sensor (71) is provided on the outer peripheral surface of the small-diameter portion (11b) of the input shaft (11) via the collar (80).

Description

REACTION FORCE ACTUATOR
The present invention relates to a reaction force actuator.
JP 2018-43731A discloses a steer-by-wire steering device. A turning device includes a steering shaft connected to a steering wheel, an angle sensor provided on the steering shaft and configured to detect a rotation angle of the steering shaft, a turning motor configured to generate a steering torque based on a detection result of the angle sensor, and a reaction force motor configured to generate a steering reaction force in the steering wheel.
In the steer-by-wire steering device described in JP 2018-43731A, the steering may become impossible if the angle sensor fails. Therefore, it is conceivable to provide two angle sensors to provide redundancy. When the two angle sensors are provided, it is advantageous in terms of cost to use the two same angle sensors. When the two angle sensors having the same configuration are attached to an outer peripheral surface of the input shaft having a uniform outer diameter, it is difficult to attach the angle sensors to the input shaft because an insertion distance of each angle sensor to the input shaft becomes long.
An object of the present invention is to improve ease of attachability of a sensor provided in a reaction force actuator.
According to one aspect of the present invention, a reaction force actuator provided in a steering device, the reaction force actuator includes: an input shaft configured to allow a steering torque to be input through a steering wheel; a reaction force shaft connected to the input shaft via a torsion bar; a first sensor and a second sensor configured to detect a rotation angle of the input shaft to control the steering device and having a same configuration; and an electric motor configured to generate a reaction force against the steering torque and input the reaction force to the reaction force shaft, the input shaft includes a large-diameter portion formed on a reaction force shaft side, and a small-diameter portion formed on a steering wheel side with respect to the large-diameter portion, a collar including a main body portion having an outer diameter same as the large-diameter portion is provided on an outer peripheral surface of the small-diameter portion, the first sensor is directly provided on an outer peripheral surface of the large-diameter portion of the input shaft, and the second sensor is provided on the outer peripheral surface of the small-diameter portion of the input shaft via the collar.
FIG. 1 is a configuration diagram of an electric power steering device according to an embodiment of the present invention. FIG. 2 is a sectional view of the reaction force actuator according to the embodiment of the present invention.
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.
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.
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 first sensor 61 and a second sensor 71 provided on an input shaft 11 of the steering shaft 10 and configured to detect a rotation angle of the input shaft 11 to control the electric power steering device 1, 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.
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.
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.
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.
The first sensor 61 and the second sensor 71 have the same configuration. However, in the present embodiment, the first sensor 61 and the second sensor 71 have different functions. The first sensor 61 functions as a torque angle sensor that detects the rotation angle of the input shaft 11 and the steering torque input to the input shaft 11. The second sensor 71 functions as an angle sensor that detects only the rotation angle of the input shaft 11. The first sensor 61 outputs a detection result of the rotation angle (specifically, a signal corresponding to the detection result) to the turning controller 6a through a cable, and outputs a detection result of the steering torque to the reaction force controller 6b described later. The second sensor 71 outputs the detection result of the rotation angle to the turning controller 6a through the cable. Details of the first sensor 61 and the second sensor 71 will be described later.
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 first sensor 61 and the second sensor 71, 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.
The turning controller 6a controls the electric motor 8 according to an operation state of the steering wheel 2 to turn the wheels 3. Specifically, the turning controller 6a sets a target turning angle based on the rotation angle of the input shaft 11 (steering wheel 2) output from the first sensor 61 and the second sensor 71 and the vehicle state information such as 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 steering of the electric power steering device 1 is controlled. The rotation angle output from one of the first sensor 61 and the second sensor 71 is used to set the target turning angle. However, in a case where an abnormality occurs in the one sensor, such as a case where the rotation angle is not output from the one sensor, or a case where a large change that does not occur in normal steering occurs in the rotation angle output from the one sensor, the rotation angle output from the other sensor is used.
In the electric power steering device 1 in which the steer-by-wire control is performed, if only one sensor for detecting the rotation angle of the input shaft 11 is provided, the steering may become impossible if the sensor fails. Therefore, in the present embodiment, in order to improve safety, two sensors (first sensor 61 and second sensor 71) are provided for redundancy. A torque of the electric motor 8 is transmitted to an output shaft 15 via a speed reducer 9.
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.
Next, the reaction force actuator 100 provided in the electric power steering device 1 will be described in detail. The reaction force actuator 100 can give a pseudo weight of the steering wheel to the steering operation of the driver.
The reaction force actuator 100 includes the input shaft 11 to which the steering torque is input via the steering wheel 2, the reaction force shaft 12 connected to the input shaft 11 via the torsion bar 13, the first sensor 61 and the second sensor 71 for controlling the electric power steering device 1, 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, and a reaction force controller 6b as a control unit that is electrically connected to the first sensor 61 and the second sensor 71 via a cable.
As shown in FIG. 2, the input shaft 11, the torsion bar 13, and the reaction force shaft 12 are provided coaxially. The input shaft 11 includes a large-diameter portion 11a formed on a reaction force shaft 12 side, a small-diameter portion 11b formed on a steering wheel 2 side with respect to the large-diameter portion 11a, and an insertion portion 11c inserted into the reaction force shaft 12. The large-diameter portion 11a has a diameter larger than that of the small-diameter portion 11b. The small-diameter portion 11b is formed to extend between the large-diameter portion 11a and one end portion (end portion on upper side in FIG. 2) of the input shaft 11. A step portion 11d is formed between the large-diameter portion 11a and the small-diameter portion 11b. A cylindrical collar 80 is provided on an outer peripheral surface of the small-diameter portion 11b. Details of the collar 80 will be described later.
The first sensor 61 is directly provided on the large-diameter portion 11a of the input shaft 11 without a collar or the like interposed therebetween. An inner diameter of an insertion hole 61a of the first sensor 61 through which the input shaft 11 is inserted is substantially the same as an outer diameter of the large-diameter portion 11a of the input shaft 11.
The first sensor 61 detects the rotation angle of the input shaft 11 and a steering torque applied to the torsion bar 13. Although detailed descriptions and showing of a method for detecting the rotation angle of the input shaft 11 are omitted because the method is a well-known technique, for example, a center gear (not shown) that rotates integrally with the input shaft 11 and two outer gears (not shown) that mesh with the center gear are used to detect a rotation angle of the center gear, that is, the rotation angle of the input shaft 11, based on a change in magnetic flux that accompanies the rotation of the two outer gears. Although the detailed descriptions and showing of the method for detecting the steering torque are omitted because the method is a well-known technique, a first rotor 61b that rotates integrally with the input shaft 11 and a second rotor 61c that rotates integrally with the reaction force shaft 12 are used, a change in a magnetic field due to a rotation angle difference between the input shaft 11 and the reaction force shaft 12 is detected by a detection coil pattern of a substrate (not shown), and the steering torque is detected.
The second sensor 71 is provided on the small-diameter portion 11b of the input shaft 11 via the collar 80. Since the second sensor 71 has the same configuration as the first sensor 61, components corresponding to those of the first sensor 61 are denoted by corresponding reference numerals. As described above, the second sensor 71 functions as an angle sensor that detects only the rotation angle of the input shaft 11 without detecting the steering torque input to the input shaft 11. Specifically, in the second sensor 71, since both a first rotor 71b corresponding to the first rotor 61b and a second rotor 71c corresponding to the second rotor 61c rotate integrally with the collar 80 (input shaft 11), the rotation angle of the input shaft 11 can be detected, but the steering torque cannot be detected.
Similarly to the turning controller 6a, the reaction force controller 6b is implemented by a microcomputer including a CPU, a ROM, and a RAM.
The speed reducer 7 includes a worm shaft 7a connected to an output shaft (not shown) of the reaction force motor 4, and a worm wheel 7b meshing with the worm shaft 7a and fixed to the reaction force shaft 12. A rotational torque of the output shaft of the reaction force motor 4 is transmitted to the reaction force shaft 12 through the worm shaft 7a and the worm wheel 7b.
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.
The reaction force actuator 100 further includes a first housing 40 that houses the first sensor 61, a second housing 50 that houses the second sensor 71, a first cover 53 that seals an opening portion 51 of the second housing 50, and a motor housing (not shown) that houses the reaction force motor 4 and the reaction force controller 6b.
The first housing 40 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 first sensor 61, and the worm shaft 7a and the worm wheel 7b of the speed reducer 7. The first housing 40 has opening portions 41 and 42 at both end portions in the axial direction, the second housing 50 is provided to the opening portion 41 through which the input shaft 11 and the torsion bar 13 are inserted, and a second cover 54 is provided to the opening portion 42 through which the reaction force shaft 12 is inserted. The second cover 54 houses the end portion of the reaction force shaft 12. The first housing 40 houses a bearing 93 that rotatably supports the reaction force shaft 12. A motor housing is connected to the first housing 40 via a bolt or the like (not shown).
The second housing 50 is formed in a substantially cylindrical shape, and houses the second sensor 71 and a part of the input shaft 11, the torsion bar 13, and the collar 80. The second housing 50 is formed in substantially the same configuration as a portion of the first housing 40 that houses the first sensor 61. The second housing 50 has opening portions 51 and 52 at both end portions in the axial direction, the first cover 53 is provided to the opening portion 51 on the steering wheel 2 side (upper side in FIG. 2), and the first housing 40 is provided to the opening portion 52 on the reaction force shaft 12 side. Accordingly, the second housing 50 is formed separately from the first housing 40 and is sandwiched between the first housing 40 and the first cover 53.
The input shaft 11 and the torsion bar 13 are inserted into the first cover 53, and a bearing 92 that rotatably supports the input shaft 11 is housed in the first cover 53. Bolts 18 are provided on the first cover 53 across the first housing 40 and the second housing 50, and the first cover 53, the first housing 40, and the second housing 50 are fixed to each other by the bolts 18.
Between the first housing 40 and the second housing 50 and between the first cover 53 and the second housing 50, O-rings 85 and 86 are provided as sealing members that are compressed in a radial direction. The O-rings 85 and 86 perform the sealing between the first housing 40 and the second housing 50 and between the first cover 53 and the second housing 50. In addition, since the O-ring 85 is provided to be compressed in the radial direction, the first housing 40 is aligned with respect to the second housing 50 by the O-ring 85. Similarly, the second housing 50 is aligned with respect to the first cover 53 by the O-ring 86.
Next, the collar 80 will be described in detail.
The collar 80 is for providing the second sensor 71 on the small-diameter portion 11b of the input shaft 11. In other words, the collar 80 increases an outer diameter of the small-diameter portion 11b in order to attach the second sensor 71, which is not fitted to the small-diameter portion 11b as it is, to the small-diameter portion 11b.
The collar 80 includes a main body portion 80a having an outer diameter same as that of the large-diameter portion 11a of the input shaft 11 and provided with the second sensor 71, a thick portion 80b having a diameter larger than that of the main body portion 80a, a thin portion 80c formed at one end portion in the axial direction (axial direction of collar 80 and input shaft 11), and a welded portion 80d formed at the other end portion in the axial direction and welded to the input shaft 11. The collar 80 is formed with a uniform inner diameter throughout and has substantially the same outer diameter as the small-diameter portion 11b of the input shaft 11.
The main body portion 80a has substantially the same outer diameter as the insertion hole 71a of the second sensor 71. The thick portion 80b has a diameter largest in the collar 80, and a lower end portion of the second sensor 71 abuts an end surface of the thick portion 80b. That is, the thick portion 80b positions the second sensor 71 with respect to the collar 80. The thin portion 80c is provided at one end portion of the collar 80 in the axial direction to be continuous with the thick portion 80b, and has a tip end portion abutting the step portion 11d of the input shaft 11. Accordingly, the collar 80 is positioned with respect to the input shaft 11. In other words, one end portion of the collar 80 in the axial direction abuts the step portion 11d of the input shaft 11, and the second sensor 71 is positioned with respect to the input shaft 11 via the collar 80. The thin portion 80c is not an essential component, and the thick portion 80b may abut the step portion 11d of the input shaft 11 without forming the thin portion 80c. The welded portion 80d is provided at the other end portion of the collar 80 in the axial direction to be continuous with the main body portion 80a, and is welded to the input shaft 11 by, for example, laser welding.
The collar 80 is not attached to the input shaft 11 when the first sensor 61 is attached. After the first sensor 61 is attached, the welded portion 80d is welded to the input shaft 11 while the tip end portion of the thin portion 80c abuts the step portion 11d, so that the collar 80 is positioned and fixed to an outer peripheral surface of the input shaft 11.
In the reaction force actuator 100 of the present embodiment, since two sensors are provided, an insertion distance of the first sensor 61 to the input shaft 11 is long. However, the first sensor 61 is attached to the input shaft 11 while the collar 80 is not provided on the small-diameter portion 11b of the input shaft 11. Therefore, the first sensor 61 can be easily attached to the large-diameter portion 11a of the input shaft 11 through the small-diameter portion 11b. The second sensor 71 can be attached to the small-diameter portion 11b of the input shaft 11 via the collar 80 by providing the collar 80 on the small-diameter portion 11b after the first sensor 61 is attached. Accordingly, the first sensor 61 and the second sensor 71 having the same configuration can be easily attached to the input shaft 11.
The configuration of the input shaft 11 having the large-diameter portion 11a and the small-diameter portion 11b in the present embodiment can also be included in a reaction force actuator in the related art in which only one non-redundant sensor is provided. Therefore, it is possible to easily make redundant only by adding the collar 80, the second sensor 71, and the second housing 50 to the reaction force actuator in the related art. In the case of the present embodiment, the reaction force actuator 100 can be made redundant only by stacking the second housing 50 that houses the second sensor 71 on the first housing 40.
According to the present embodiment described above, the following effects are achieved.
In the reaction force actuator 100, since the input shaft 11 includes the small-diameter portion 11b, the first sensor 61 can be easily attached to the large-diameter portion 11a of the input shaft 11 through the small-diameter portion 11b. The second sensor 71 can be attached to the small-diameter portion 11b of the input shaft 11 via the collar 80 by providing the collar 80 on the small-diameter portion 11b after the first sensor 61 is attached. Accordingly, the first sensor 61 and the second sensor 71 having the same configuration can be easily attached to the input shaft 11, and thus, attachability of the first sensor 61 and the second sensor 71 is improved.
Hereinafter, configurations, operations, and effects of the embodiment of the present invention will be collectively described.
The reaction force actuator 100 provided in the electric power steering device 1 as a steering device includes: the input shaft 11 to which the steering torque is input via the steering wheel 2; the reaction force shaft 12 connected to the input shaft 11 via the torsion bar 13; the first sensor 61 and the second sensor 71 that detect the rotation angle of the input shaft 11 to control the electric power steering device 1 and have the same configuration as each other; and 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, in which the input shaft 11 includes the large-diameter portion 11a formed on the reaction force shaft 12 side and the small-diameter portion 11b formed on the steering wheel 2 side with respect to the large-diameter portion 11a, the collar 80 including the main body portion 80a having the same outer diameter as the large-diameter portion 11a is provided on the outer peripheral surface of the small-diameter portion 11b, the first sensor 61 is provided directly on an outer peripheral surface of the large-diameter portion 11a of the input shaft 11, and the second sensor 71 is provided on the outer peripheral surface of the small-diameter portion 11b of the input shaft 11 via the collar 80.
In this configuration, since the input shaft 11 includes the small-diameter portion 11b, the first sensor 61 can be easily attached to the large-diameter portion 11a of the input shaft 11 through the small-diameter portion 11b before the collar 80 is provided on the input shaft 11. The second sensor 71 can be attached to the small-diameter portion 11b of the input shaft 11 via the collar 80 by providing the collar 80 on the small-diameter portion 11b after the first sensor 61 is attached. Accordingly, the first sensor 61 and the second sensor 71 having the same configuration can be easily attached to the input shaft 11. The attachability of the first sensor 61 and the second sensor 71 is improved.
In the reaction force actuator 100, one end portion of the collar 80 in the axial direction abuts the step portion 11d formed between the large-diameter portion 11a and the small-diameter portion 11b of the input shaft 11.
In this configuration, the second sensor 71 can be positioned with respect to the input shaft 11 via the collar 80.
The reaction force actuator 100 further includes the first housing 40 that houses the first sensor 61 and the second housing 50 that houses the second sensor 71, and the first housing 40 and the second housing 50 are formed separately.
In this configuration, the reaction force actuator 100 can be made redundant only by stacking the second housing 50 that houses the second sensor 71 on the first housing 40.
In the reaction force actuator 100, the O-ring 85 as a sealing member compressed in the radial direction is provided between the first housing 40 and the second housing 50.
In this configuration, the second housing 50 can be aligned with respect to the first housing 40 while the O-ring 85 performs the sealing between the first housing 40 and the second housing 50.
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.
The second sensor 71 may have a function of a torque angle sensor that detects both the rotation angle of the input shaft 11 and the steering torque.
The second housing 50 and the first cover 53 may be integrally formed.
With respect to the above description, the contents of application No. 2024-38914, with a filing date of March 13, 2024 in Japan, are incorporated herein by reference.

Claims (4)

  1. A reaction force actuator provided in a steering device, the reaction force actuator comprising:
    an input shaft configured to allow a steering torque to be input through a steering wheel;
    a reaction force shaft connected to the input shaft via a torsion bar;
    a first sensor and a second sensor configured to detect a rotation angle of the input shaft to control the steering device and having a same configuration; and
    an electric motor configured to generate a reaction force against the steering torque and input the reaction force to the reaction force shaft, wherein
    the input shaft includes
    a large-diameter portion formed on a reaction force shaft side, and
    a small-diameter portion formed on a steering wheel side with respect to the large-diameter portion,
    a collar including a main body portion having an outer diameter same as the large-diameter portion is provided on an outer peripheral surface of the small-diameter portion,
    the first sensor is directly provided on an outer peripheral surface of the large-diameter portion of the input shaft, and
    the second sensor is provided on the outer peripheral surface of the small-diameter portion of the input shaft via the collar.
  2. The reaction force actuator according to claim 1, wherein
    one end portion of the collar in an axial direction abuts a step portion formed between the large-diameter portion and the small-diameter portion of the input shaft.
  3. The reaction force actuator according to claim 1, further comprising:
    a first housing configured to house the first sensor; and
    a second housing configured to house the second sensor, wherein
    the first housing and the second housing are formed separately.
  4. The reaction force actuator according to claim 3, wherein
    a sealing member compressed in a radial direction is provided between the first housing and the second housing.

PCT/JP2025/004547 2024-03-13 2025-02-12 Reaction force actuator Pending WO2025192138A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2024038914 2024-03-13
JP2024-038914 2024-03-13

Publications (1)

Publication Number Publication Date
WO2025192138A1 true WO2025192138A1 (en) 2025-09-18

Family

ID=97063367

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2025/004547 Pending WO2025192138A1 (en) 2024-03-13 2025-02-12 Reaction force actuator

Country Status (1)

Country Link
WO (1) WO2025192138A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006197690A (en) * 2005-01-12 2006-07-27 Jtekt Corp Electric actuator device
US20190263442A1 (en) * 2016-09-20 2019-08-29 Hitachi Automotive Systems, Ltd. Steering apparatus
JP2022154924A (en) * 2021-03-30 2022-10-13 日立Astemo株式会社 Sensor device, electrically driven power steering device and sensor device manufacturing method
JP2024011419A (en) * 2022-07-14 2024-01-25 カヤバ株式会社 electric power steering device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006197690A (en) * 2005-01-12 2006-07-27 Jtekt Corp Electric actuator device
US20190263442A1 (en) * 2016-09-20 2019-08-29 Hitachi Automotive Systems, Ltd. Steering apparatus
JP2022154924A (en) * 2021-03-30 2022-10-13 日立Astemo株式会社 Sensor device, electrically driven power steering device and sensor device manufacturing method
JP2024011419A (en) * 2022-07-14 2024-01-25 カヤバ株式会社 electric power steering device

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