JP2017144960A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device that allows a driver to perform steering operation even if adhesion is caused in a gear mechanism.SOLUTION: The steering device comprises a motor that generates rotation force corresponding to steering torque applied to a steering shaft, a gear mechanism that amplifies the rotation force at a predetermined gear reduction ratio to generate steering force, and an output portion that outputs the steering force to a turning mechanism connected to wheels. The output portion includes a transmitting portion that transmits the steering force to the turning mechanism and a releasing portion that releases mechanical connection between the transmitting portion and the gear mechanism. When load torque generated at the transmitting portion due to rotation of the steering shaft in a state where the gear mechanism is adhered thereto surpasses a threshold, the releasing portion releases the mechanical connection. When the releasing portion releases the mechanical connection, the transmitting portion rotates around a rotation center shaft to transmit the rotation of the steering shaft to the turning mechanism.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steering device that outputs a steering force for changing the direction of a wheel.

  A steering device that outputs a steering force for changing the direction of a wheel is mounted on various vehicles. Patent Document 1 discloses a steering device having a gear mechanism that amplifies a rotational force from a motor at a predetermined reduction ratio and outputs a large steering force. The steering mechanism designed to change the direction of the wheels is driven by a large steering force from the steering device. The steering force is transmitted to the wheels through the steering mechanism, and changes the direction of the wheels.

JP 2007-1564 A

  The steering device operates in various usage environments. Due to vibration or impact force, foreign matter may enter the steering device. The foreign matter that has entered the steering device may cause the gear mechanism to stick. The fixed gear mechanism may obstruct the driver's steering operation.

  An object of the present invention is to provide a steering device that enables a driver to perform a steering operation even when the gear mechanism is fixed.

  A steering apparatus according to one aspect of the present invention includes a motor that generates a rotational force according to a steering torque applied to a steering shaft, a gear mechanism that generates the steering force by amplifying the rotational force with a predetermined reduction ratio, An output unit that outputs a steering force to a steering mechanism connected to the wheels. The output unit includes a transmission unit that transmits the steering force to the steering mechanism, and a release unit that releases a mechanical connection between the transmission unit and the gear mechanism. The transmission unit is mechanically connected to the steering shaft and rotates around a predetermined rotation center axis so that the steering torque is reduced when the steering force is transmitted. When the load torque generated in the transmission unit due to the rotation of the steering shaft under the fixing of the gear mechanism exceeds a threshold value, the release unit releases the mechanical connection. When the release unit releases the mechanical connection, the transmission unit rotates around the rotation center axis and transmits the rotation of the steering shaft to the steering mechanism.

  According to the above configuration, since the transmission unit is mechanically connected to the steering shaft, the steering torque is applied to the steering shaft when the driver rotates the steering shaft. The motor generates a rotational force according to the steering torque. The rotational force is amplified by a gear mechanism at a predetermined reduction ratio to become a steering force. When the steering force is transmitted to the transmission unit, the transmission unit rotates around a predetermined rotation center axis so that the steering torque of the steering shaft is reduced. During this time, the steering force is transmitted from the transmission unit to the steering mechanism, and the direction of the wheels is changed. Therefore, the change of the direction of the wheel according to the rotation of the steering shaft is achieved.

  When the driver rotates the steering shaft while the gear mechanism is fixed, the load torque applied to the transmission unit increases. When the load torque exceeds the threshold value, the mechanical connection between the transmission unit and the gear mechanism is released by the release unit. Therefore, the transmission unit can rotate around the rotation center axis in accordance with the rotation operation of the driver with respect to the steering shaft. As a result, even when the gear mechanism is fixed, the rotation of the steering shaft is transmitted to the steering mechanism by the transmission unit.

  With regard to the above configuration, the transmission unit may include an output shaft unit having a first connection unit connected to the steering shaft and a second connection unit connected to the steering mechanism.

  According to the above configuration, since the first connecting portion is connected to the steering shaft, the steering torque is applied to the steering shaft when the driver rotates the steering shaft. If the gear mechanism is not fixed, the motor generates a rotational force corresponding to the steering torque generated on the steering shaft, and then the rotational force is amplified by the gear mechanism to become a steering force. At this time, the output shaft portion rotates around the rotation center axis so that the steering torque of the steering shaft is reduced. Since the second connecting portion is connected to the steering mechanism, the rotation of the transmission portion around the rotation center axis is transmitted to the steering mechanism.

  When the driver rotates the steering shaft while the gear mechanism is fixed, the first coupling portion is coupled to the steering shaft, so that the gear mechanism restrains the rotation of the output shaft around the rotation center axis. Thus, the steering shaft tries to rotate the output shaft portion. As a result, the load torque generated in the output shaft portion increases. When the load torque exceeds the threshold value, the mechanical connection between the output shaft portion and the gear mechanism is released by the release portion. Therefore, the output shaft portion can rotate around the rotation center axis in accordance with the rotation operation of the driver with respect to the steering shaft. As a result, even when the gear mechanism is fixed, the rotation of the steering shaft is transmitted to the steering mechanism by the output shaft portion.

  With respect to the above configuration, the output shaft portion may include a rotation shaft extending along the rotation center axis. The first connection part may include a connection gear attached to the rotating shaft. The connection gear may be connected to a steering gear that rotates together with the steering shaft.

  According to the above configuration, the coupling gear is coupled to the steering gear that rotates together with the steering shaft. Therefore, when the driver rotates the steering shaft, steering torque is applied to the steering shaft. If the gear mechanism is not fixed, the motor generates a rotational force corresponding to the steering torque generated on the steering shaft, and then the rotational force is amplified by the gear mechanism to become a steering force. At this time, the rotating shaft rotates around the rotation center axis so that the steering torque of the steering shaft is reduced. Since the second connecting portion is connected to the steering mechanism, the rotation of the rotating shaft around the rotation center axis is transmitted to the steering mechanism.

  When the driver rotates the steering shaft while the gear mechanism is fixed, the connecting gear is connected to the steering gear, so that the gear mechanism restrains the rotation of the rotating shaft around the rotation center axis, The steering shaft tries to rotate the rotating shaft. As a result, the load torque generated in the rotating shaft increases. When the load torque exceeds the threshold value, the mechanical connection between the rotating shaft and the gear mechanism is released by the release unit. Therefore, the rotation shaft can rotate around the rotation center axis in accordance with the rotation operation of the driver with respect to the steering shaft. As a result, even when the gear mechanism is fixed, the rotation of the steering shaft is transmitted to the steering mechanism by the rotating shaft.

  With regard to the above configuration, the output unit may include a carrier coupled to the gear mechanism and rotating around the rotation center axis. The rotating shaft may include a narrow detail having a specifically small cross section between the rotating shaft and the carrier as the release portion. When the load torque exceeds the threshold, the narrow details may break.

  According to the above configuration, when the load torque exceeds the threshold value, the narrow details are broken, so that the mechanical connection between the coupling gear and the gear mechanism is released by the narrow details. Therefore, the connection gear is rotated by the rotation operation by the rotation operation of the driver with respect to the steering shaft. Since the rotation shaft also rotates integrally with the rotation of the connecting gear, the direction of the wheel is changed according to the rotation operation of the driver with respect to the steering shaft.

  With regard to the above configuration, the gear mechanism includes an outer cylinder in which a plurality of internal teeth are formed, a rocking gear that meshes with the plurality of internal teeth, and the center of the rocking gear circulates around the rotation center axis of the output unit. As described above, a crank assembly that swings and rotates the swing gear may be included. The carrier may be connected to the crank assembly and rotate about the rotation center axis in the outer cylinder. The narrow details may be accommodated in the outer cylinder.

  According to the above configuration, since the connection gear is connected to the steering gear, the steering torque is applied to the steering shaft when the driver rotates the steering shaft. The motor generates a rotational force according to the steering torque. Since the oscillating gear meshing with the inner teeth of the outer cylinder is oscillated and rotated by the crank assembly, the gear mechanism amplifies the rotational force from the motor and generates a large steering force with a large reduction ratio. Can do. Since the carrier and the rotating shaft rotate around the rotation center axis under a large steering force, the driver can change the direction of the wheel with a small force.

  When the driver rotates the steering shaft while the gear mechanism is fixed, the connection gear tends to be rotated by the steering gear, while the gear mechanism inhibits the rotation of the rotation shaft and the connection gear. As a result, the load torque applied to the rotating shaft increases. When the load torque exceeds the threshold value, it breaks. Since the narrow details are accommodated in the outer cylinder, most of the fragments generated due to the fracture of the narrow details can remain in the outer cylinder.

  With regard to the above configuration, the output unit may include a carrier coupled to the gear mechanism and rotating around the rotation center axis. The release unit may include a clutch mechanism disposed between the rotating shaft and the carrier. The clutch mechanism may include a first clutch plate disposed between the carrier and the rotating shaft, and a second clutch plate disposed between the first clutch plate and the rotating shaft. Good. If the load torque does not exceed the threshold value, the first clutch plate and the second clutch plate may rotate together. When the load torque exceeds the threshold value, one of the first clutch plate and the second clutch plate may rotate independently of the other of the first clutch plate and the second clutch plate. Good.

  According to the above configuration, when the load torque exceeds the threshold value, one of the first clutch plate and the second clutch plate rotates independently of the other of the first clutch plate and the second clutch plate. The connection gear is rotated by a rotation operation by a rotation operation of the driver with respect to the steering shaft. Since the rotation shaft also rotates integrally with the rotation of the connecting gear, the direction of the wheel is changed according to the rotation operation of the driver with respect to the steering shaft.

  With respect to the above configuration, the second connecting part may include a spline shaft part or a key structure part formed on the rotating shaft. The steering mechanism may include a pitman arm attached to the spline shaft portion or the key structure portion.

  According to the above configuration, when the release portion releases the mechanical connection, the coupling gear transmits the steering torque to the pitman arm through the rotary shaft and the spline shaft portion or the key structure portion. Even under the fixed condition, it is changed according to the rotation operation of the driver with respect to the steering shaft.

  With regard to the above configuration, the second connecting portion may include a pinion that rotates integrally with the rotation shaft around the rotation center axis. The steering mechanism may include a rack that meshes with the pinion.

  According to the above configuration, when the release portion releases the mechanical connection, the coupling gear transmits the steering torque to the rack through the rotating shaft and the pinion. Is changed according to the rotation operation of the driver.

  The above-described steering device enables a driver to perform a steering operation even when the gear mechanism is fixed.

It is a notional block diagram of the steering device of a 1st embodiment. It is a schematic sectional drawing of the steering device of a 2nd embodiment. FIG. 3 is a schematic sectional view taken along line AA shown in FIG. 2. It is a schematic sectional drawing of the steering device of a 3rd embodiment. It is a schematic sectional drawing of the steering device of a 4th embodiment.

<First Embodiment>
A steering device having a gear mechanism that amplifies the rotational force generated by the motor allows the driver to rotate the steering shaft with a small force and change the direction of the wheels. However, if sticking occurs in the gear mechanism, the gear mechanism obstructs the rotation operation of the driver with respect to the steering shaft. In the first embodiment, an exemplary steering device that allows the direction of the wheel to be changed according to the rotation operation of the driver with respect to the steering shaft even when the gear mechanism is fixed will be described.

  FIG. 1 is a conceptual block diagram of the steering device 100 of the first embodiment. The steering device 100 will be described with reference to FIG.

  The steering apparatus 100 includes a motor 200, a gear mechanism 300, and an output unit 400. The output unit 400 includes a release unit 410, a first connection unit 420, and a second connection unit 430.

  FIG. 1 shows a steering wheel STW and a steering shaft STS extending from the steering wheel STW. The steering shaft STS is mechanically connected to the first connecting part 420. When the driver rotates the steering wheel STW, a steering torque is generated in the steering shaft STS. The connection structure between the steering shaft STS and the first connection part 420 may be constructed using a gear. Alternatively, the connection structure between the steering shaft STS and the first connection part 420 may be a link mechanism or other mechanical connection structure. The principle of this embodiment is not limited to a specific mechanical connection structure between the first connecting portion 420 and the steering shaft STS.

  FIG. 1 further shows the control device CTR. Control device CTR includes a torque sensor TQS and a signal generation unit SGT. The torque sensor TQS detects the steering torque applied to the steering shaft STS. Known torque detection techniques may be applied to the torque sensor TQS. The principle of this embodiment is not limited to a specific type of torque sensor TQS.

  If the torque sensor TQS is required to be directly connected to the steering shaft STS in order to detect the steering torque generated in the steering shaft STS, the torque sensor TQS is mechanically connected to the steering shaft STS. Is done. In other cases, the torque sensor TQS may not be directly connected to the steering shaft STS. The mechanical or electrical connection structure between the torque sensor TQS and the steering shaft STS depends on the performance of the torque sensor TQS. Therefore, the principle of the present embodiment is not limited to a specific connection structure between the steering shaft STS and the torque sensor TQS.

  The torque sensor TQS generates torque data representing the detected steering torque. Torque data is output from the torque sensor TQS to the signal generator SGT.

  The signal generator SGT generates a drive signal so that the steering torque represented by the torque data is reduced. The drive signal is output from the signal generation unit SGT to the motor 200.

  The motor 200 generates a rotational force according to the drive signal. The rotational force is output to the gear mechanism 300 as the rotation of the motor 200. The gear mechanism 300 amplifies the rotational force with a predetermined reduction ratio to generate a steering force. The gear mechanism 300 may include a swing gear and an internal gear. Alternatively, the gear mechanism 300 may include a planetary gear and a sun gear. The designer can employ various mechanisms using gears as the gear mechanism 300. The principle of the present embodiment is not limited to a specific structure of the gear mechanism 300.

  The steering force is sequentially transmitted to the release unit 410, the first connection unit 420, and the second connection unit 430. Alternatively, the steering force may be sequentially transmitted to the release unit 410, the second connection unit 430, and the first connection unit 420. The principle of the present embodiment is not limited to a specific positional relationship between the first connecting part 420 and the second connecting part 430.

  The 2nd connection part 430 is connected with the steering mechanism STM. The steering force is transmitted from the second connecting portion 430 to the steering mechanism STM. The steering mechanism STM is connected to wheels (not shown) of a vehicle (not shown). The steered mechanism STM changes the direction of the wheel according to the steering force. The steered mechanism STM may be a pitman arm. Alternatively, the steering mechanism STM may be a rack. The principle of this embodiment is not limited to a specific structure of the steering mechanism STM. In the present embodiment, the transmission unit is exemplified by the first connection unit 420 and the second connection unit 430.

  The structure of the 2nd connection part 430 may be determined so that it may suit the components used as a steering mechanism STM. If the steering mechanism STM is a pitman arm, the second connecting portion 430 may be a spline shaft portion inserted into the pitman arm. Alternatively, the second connection part 430 may be a key structure part to which a key inserted into the pitman arm is attached. The principle of the present embodiment is not limited to the specific structure of the second connecting portion 430.

  When the fixing occurs in the gear mechanism 300, the transmission of the steering force from the gear mechanism 300 to the output unit 400 is lost. As a result, even if the driver rotates the steering handle STW, the output unit 400 maintains a stationary state. Since the steering shaft STS is restrained by the first connecting portion 420, the steering torque applied to the steering shaft STS increases. The increased steering torque is transmitted to the output unit 400 through the first connecting unit 420 and becomes a load torque that acts on the output unit 400.

  The release unit 410 is designed so that the mechanical connection between the first coupling unit 420 and the gear mechanism 300 is released when the load torque exceeds a threshold value. The release unit 410 may be designed as a part having a mechanical strength that is specifically weak in the output unit 400. Alternatively, the release unit 410 may be a clutch mechanism. The principle of the present embodiment is not limited to a specific structure of the release unit 410.

  When the releasing unit 410 releases the mechanical connection between the first connecting unit 420 and the gear mechanism 300, the first connecting unit 420 and the second connecting unit 430 are not restrained by the gear mechanism 300, and the steering shaft The operation can be performed according to the steering torque transmitted from the STS to the first connection unit 420. As a result, even when the gear mechanism 300 is fixed, the steering mechanism STM can change the direction of the wheels using the steering torque transmitted through the steering shaft STS, the first connecting portion 420, and the second connecting portion 430. it can.

Second Embodiment
The designer can design various steering devices based on the design principle described in relation to the first embodiment. In the second embodiment, an exemplary steering device is described.

  FIG. 2 is a schematic cross-sectional view of the steering device 100A of the second embodiment. FIG. 3 is a schematic cross-sectional view taken along line AA shown in FIG. The steering device 100A will be described with reference to FIGS.

  The steering device 100A includes a motor 200A, a gear mechanism 300A, and an output unit 400A. The motor 200A corresponds to the motor 200 described with reference to FIG. The description regarding the motor 200 may be incorporated into the motor 200A. The gear mechanism 300A corresponds to the gear mechanism 300 described with reference to FIG. The description regarding the gear mechanism 300 may be applied to the gear mechanism 300A. The output unit 400A corresponds to the output unit 400 described with reference to FIG. The description regarding the output unit 400 may be incorporated into the output unit 400A.

  The motor 200 </ b> A includes a housing 210 and a rotating shaft 220. The casing 210 includes a coil and a stator core, and generates a rotational force in accordance with a drive signal. The rotating shaft 220 extends from the housing 210 along the output axis OPA. The rotational force generated in the housing 210 is output as the rotation of the rotary shaft 220. The rotating shaft 220 rotates around the output axis OPA. A gear portion 221 is formed at the tip of the rotating shaft 220.

  The gear mechanism 300 </ b> A includes an outer cylinder 310, three crank assemblies 320 (FIG. 2 shows one of the three crank assemblies 320), and a swing portion 330. The outer cylinder 310 forms an internal space in which the three crank assemblies 320 and the swing part 330 are accommodated. Each of the three crank assemblies 320 is connected to the gear portion 221 of the motor 200A within the outer cylinder 310 and rotates around the transmission shaft TMA. The transmission shaft TMA extends substantially parallel to the output shaft OPA at a position away from the output shaft OPA by a predetermined distance. The rotation of the crank assembly 320 around the transmission shaft TMA causes the swinging portion 330 to swing. The swinging rotation of the swinging part 330 causes the output part 400A to rotate around the output shaft OPA.

  Each of the three crank assemblies 320 includes a transmission gear 321, a crankshaft 322, two tapered bearings 323 and 324, and two needle bearings 325 and 326. The crankshaft 322 includes two journals 341 and 342 and two eccentric portions 343 and 344. The journals 341 and 342 rotate coaxially around the transmission axis TMA. The journal 342 is located on the opposite side of the journal 341.

  The transmission gear 321 and the taper bearing 323 are attached to the journal 341. The transmission gear 321 meshes with the gear portion 221 of the rotary shaft 220. The tapered bearing 324 is attached to the journal 342.

  The eccentric part 343 is located between the journals 341 and 342. The eccentric part 344 is located between the eccentric part 343 and the journal 342. The eccentric portions 343 and 344 are eccentric from the transmission shaft TMA. The eccentric part 343 is different from the eccentric part 344 in the eccentric direction.

  Since the transmission gear 321 that meshes with the gear portion 221 of the motor 200A is attached to the journal 341, the journals 341 and 342 rotate around the transmission axis TMA according to the rotation of the rotation shaft 220 of the motor 200A. During this time, the eccentric portions 343 and 344 rotate eccentrically with respect to the transmission shaft TMA.

  The outer cylinder 310 is fixed to the motor 200A. The outer cylinder 310 includes a first cylinder part 311, a second cylinder part 312, and a third cylinder part 313.

  The first tube portion 311 includes an end wall 314 and a peripheral wall 315. The end wall 314 is in close contact with the housing 210 of the motor 200A. The peripheral wall 315 protrudes from the substantially circular outer peripheral edge of the end wall 314 and surrounds the rotation shaft 220 and the transmission gear 321.

  The second cylindrical portion 312 includes a peripheral wall 316 and a plurality of internal tooth pins 317. The peripheral wall 316 surrounds the eccentric portions 343 and 344 and the swinging portion 330. Each of the plurality of internal tooth pins 317 is a columnar member extending in the extending direction of the output shaft OPA. Each of the plurality of internal tooth pins 317 is fitted into a groove formed on the inner surface of the peripheral wall 316. Therefore, the plurality of internal tooth pins 317 are appropriately held by the peripheral wall 316.

  As shown in FIG. 3, the plurality of internal tooth pins 317 are arranged at a substantially constant interval around the output shaft OPA. A half circumferential surface of each of the plurality of internal teeth pins 317 protrudes from the inner surface of the circumferential wall 316 toward the output shaft OPA. Therefore, the plurality of internal tooth pins 317 can function as internal teeth of the steering device 100A. In the present embodiment, the plurality of internal teeth are exemplified by a plurality of internal teeth pins 317 arranged in an annular shape.

  As shown in FIG. 2, the third cylindrical portion 313 includes a peripheral wall 318 and an end wall 319. The peripheral wall 318 of the third cylinder part 313 is in close contact with the edge of the peripheral wall 316 of the second cylinder part 312. The end wall 319 partially closes a substantially circular space surrounded by the peripheral wall 318.

  The swing part 330 includes two swing gears 331 and 332. Three circular through holes are formed in the rocking gear 331. The three crank assemblies 320 are inserted through the three circular opening holes of the swing gear 331. The needle bearings 325 of the three crank assemblies 320 are fitted into the three circular through holes, respectively. The swing gear 332 is formed with three circular through holes. The three crank assemblies 320 are inserted through the three circular opening holes of the swing gear 332. The needle bearing 326 of each of the three crank assemblies 320 is fitted into each of the three circular through holes.

  The steering device 100A according to the present embodiment includes two oscillating gears 331 and 332. Alternatively, the steering device may have a single rocking gear. Further alternatively, the steering device may have more than two oscillating gears. The principle of this embodiment is not limited at all depending on how many swing gears are incorporated in the steering device.

  The oscillating gears 331 and 332 mesh with an internal tooth ring formed by a plurality of internal tooth pins 317. During the rotation of the crank assembly 320, the swing gears 331 and 332 are swung and rotated by the eccentric portions 343 and 344. During this time, the centers of the rocking gears 331 and 332 move around the output shaft OPA. The oscillating rotational motion of the oscillating gears 331 and 332 is transmitted to a portion (for example, the crank assembly 320) connected to the oscillating gears 331 and 332. In the present embodiment, the rotation center axis is exemplified by the output axis OPA.

  As described above, the eccentric portions 343 and 344 are different in the eccentric direction. Therefore, a circular phase difference is generated in the circular movement of the centers of the rocking gears 331 and 332. For example, the eccentric parts 343 and 344 may be designed such that a 180 ° revolution phase difference is generated in the revolution movement of the centers of the rocking gears 331 and 332. In this case, the oscillating gear 331 can mesh with substantially half of the plurality of internal gear pins 317, while the oscillating gear 332 can mesh with the remaining internal gear pins 317.

  The output part 400 </ b> A includes a carrier 500 and an output shaft part 600. The carrier 500 rotates around the output shaft OPA within the outer cylinder 310. The output shaft portion 600 is attached to the carrier 500. The pitman arm PTM is attached to the output shaft portion 600 outside the outer cylinder 310. The pitman arm PTM cooperates with a tie rod arm (not shown) connected to a wheel (not shown) to form the steering mechanism STM described with reference to FIG.

  The carrier 500 includes a base portion 510 and an end plate portion 520. The end plate part 520 is located between the base part 510 and the end wall 314 of the first cylinder part 311.

  The base 510 includes a substrate portion 511 (see FIG. 2) and three shafts 512 (see FIG. 3). The three shafts 512 protrude from the substrate part 511 toward the end plate part 520. Each of the rocking gears 331 and 332 is formed with three trapezoidal through holes. The three shafts 512 are inserted into these trapezoidal through holes. The sizes of these trapezoidal through holes are set so that no interference occurs between the rocking gears 331 and 332 and the shaft 512.

  The end plate portion 520 is fixed to the front end surfaces of the three shafts 512. Therefore, the rocking gears 331 and 332 rotate and rotate between the end plate portion 520 and the substrate portion 511.

  Three through holes 513 are formed in the substrate portion 511 (FIG. 2 shows one of the three through holes 513). The taper bearings 324 of the three crank assemblies 320 are fitted into the three through holes 513, respectively. Three through holes 521 are formed in the end plate portion 520 (FIG. 2 shows one of the three through holes 521). The tapered bearings 323 of the three crank assemblies 320 are fitted in the three through holes 521, respectively. Accordingly, the carrier 500 is coupled to the crank assembly 320.

  The oscillating rotational movements of the oscillating gears 331 and 332 are transmitted to the carrier 500 through the three crank assemblies 320. Since the three crank assemblies 320 rotate around the output shaft OPA during the swinging rotation of the swing gears 331 and 332, the carrier 500 can rotate around the output shaft OPA.

  The output shaft portion 600 includes a mounting plate 610, a narrow detail 410A, a shaft 430A, and a connecting gear 420A. The mounting plate 610, the narrow details 410A, and the shaft 430A are integrally formed. The narrow detail 410A corresponds to the release unit 410 described with reference to FIG. The description regarding the cancellation | release part 410 is used for the narrow detail 410A. The connecting gear 420A corresponds to the first connecting portion 420 described with reference to FIG. The description regarding the first connecting portion 420 is applied to the connecting gear 420A.

  The mounting plate 610 is a disk-shaped part that comes into contact with the end surface of the substrate portion 511 (the end surface facing the end wall 319 of the third cylindrical portion 313). The center of the mounting plate 610 substantially coincides with the output shaft OPA. The mounting plate 610 is fixed to the end surface of the base plate portion 511 (the end surface facing the end wall 319 of the third cylinder portion 313) with a bolt BLT. Therefore, the mounting plate 610 can be separated from the carrier 500.

  The narrow detail 410A protrudes from the mounting plate 610 toward the shaft 430A along the output axis OPA. The narrow detail 410A is integrally connected to the mounting plate 610 and the shaft 430A. The narrow detail 410A has a smaller cross section than the mounting plate 610 and the shaft 430A in a virtual plane (not shown) orthogonal to the output axis OPA. Therefore, the allowable torsional stress of the narrow details 410A is smaller than the allowable torsional stress of the mounting plate 610 and the shaft 430A. When torque is applied to the shaft 430A that causes a torsional stress in the narrow detail 410A that exceeds the allowable torsional stress of the narrow detail 410A, the narrow detail 410A is broken. In the present embodiment, the threshold value is exemplified by the allowable torque determined from the allowable torsional stress and the cross-sectional area of the narrow detail 410A.

  As shown in FIG. 2, the narrow detail 410 </ b> A is disposed in the outer cylinder 310. Therefore, most of the fragments generated by the fracture of the narrow details 410A are confined in the outer cylinder 310. As a result, the vehicle (not shown) on which the steering device 100A is mounted is not easily damaged by the fragments of the narrow details 410A.

  The shaft 430A extends along the output axis OPA from the narrow detail 410A toward the pitman arm PTM. The shaft 430 </ b> A includes a base end portion 431 and a front end portion 432 on the side opposite to the base end portion 431. The narrow detail 410A is integrally connected to the base end 431. The distal end portion 432 is located on the opposite side of the proximal end portion 431. The proximal end portion 431 is located inside the outer cylinder 310, while the distal end portion 432 is located outside the outer cylinder 310. The pitman arm PTM is attached to the tip 432. The tip portion 432 corresponds to the second connecting portion 430 described with reference to FIG. The description regarding the second connecting portion 430 may be incorporated into the tip portion 432. In the present embodiment, the rotating shaft is exemplified by the shaft 430A.

  Spline processing may be applied to the tip 432. In this case, the tip 432 of the shaft 430A is processed into a spline shaft. A spline hole complementary to the tip 432 of the shaft 430A is formed in the pitman arm PTM. As a result, the pitman arm PTM can rotate integrally with the shaft 430A. Alternatively, a keyway may be cut into the tip 432. The pitman arm PTM may be attached to the distal end portion 432 via a key fitted in the key groove. As a result, the pitman arm PTM can rotate integrally with the shaft 430A.

  The steering device 100 </ b> A includes a gear box cylinder 440. The gear box cylinder 440 includes a substantially cylindrical peripheral wall 441 and an end wall 442 that partially closes a substantially circular space surrounded by the peripheral wall 441. The edge of the peripheral wall 441 of the gear box cylinder 440 is in close contact with the end wall 319 of the third cylinder portion 313. The gear box cylinder 440 forms a gear box in which the coupling gear 420A is accommodated in cooperation with the end wall 319 of the third cylinder portion 313.

  A through hole 443 is formed in the end wall 319 of the third cylindrical portion 313. A through hole 444 is formed in the end wall 442 of the gear box cylinder 440. The output shaft OPA substantially coincides with the centers of the through holes 443 and 444. The shaft 430A extends along the output axis OPA and passes through the through holes 443 and 444. The pitman arm PTM is connected to the tip 432 of the shaft 430A outside the outer cylinder 310 and the gear box cylinder 440. The pitman arm PTM extends in a direction substantially orthogonal to the output shaft OPA. While the carrier 500 rotates, the pitman arm PTM swings in a plane orthogonal to the output axis OPA.

  The steering device 100A includes two main bearings 445 and 446 that define the output shaft OPA. The main bearing 446 is located between the main bearing 445 and the pitman arm PTM. The main bearing 445 is fitted into a through hole 443 formed in the end wall 319 of the third cylinder portion 313. The main bearing 446 is fitted into a through hole 444 formed in the end wall 442 of the gear box cylinder 440. The shaft 430A passes through the main bearings 445 and 446. Therefore, the shaft 430A is appropriately held by the main bearings 445 and 446.

  FIG. 2 schematically shows the steering shaft STS and the worm gear WMG. The worm gear WMG is integrally formed at the lower end of the steering shaft STS. The worm gear WMG rotates together with the steering shaft STS according to the steering torque applied to the steering shaft STS under the control principle described in relation to the first embodiment. The connecting gear 420A is attached to the shaft 430A between the main bearings 445 and 446. The connecting gear 420A meshes with the worm gear WMG. In the present embodiment, the steering gear is exemplified by a worm gear WMG. Alternatively, the steering gear may be other types of gear parts. The principle of this embodiment is not limited to a particular type of gear component used as a steering gear.

  While the gear mechanism 300A is operating normally, the rotational force output by the motor 200A is amplified at a predetermined reduction ratio by the gear mechanism 300A and becomes a large steering force. The steering force is transmitted to the carrier 500 and the output shaft unit 600. As a result, the pitman arm PTM can swing around the output shaft OPA together with the output shaft portion 600.

  When the driver rotates the steering shaft STS with the gear mechanism 300A fixed, a rotational force is applied to the connection gear 420A that meshes with the worm gear WMG at the lower end of the steering shaft STS. The rotational force applied to the connecting gear 420A twists the output shaft portion 600. Since the narrow detail 410A has a specifically small cross-sectional area, twisting of the output shaft portion 600 results in a fracture of the narrow detail 410A. When the narrow detail 410A is broken, the shaft 430A can rotate according to the rotational force applied to the connection gear 420A without being constrained by the gear mechanism 300A. As a result, the pitman arm PTM attached to the shaft 430A can swing according to the rotation of the steering shaft STS.

  In the present embodiment, the connecting gear 420A is located between the narrow detail 410A and the pitman arm PTM. Alternatively, the pitman arm PTM may be located between the connecting gear 420A and the narrow detail 410A.

<Third Embodiment>
The steered mechanism may have a rack instead of the pitman arm. In the third embodiment, an exemplary steering device for driving a rack will be described.

  FIG. 4 is a schematic cross-sectional view of the steering device 100B of the third embodiment. The steering device 100B will be described with reference to FIGS. 1 and 4. The description of the second embodiment is applied to elements having the same reference numerals as those of the second embodiment.

  The steering device 100B includes a motor 200A, a gear mechanism 300A, a gear box cylinder 440, and main bearings 445 and 446. The description of the second embodiment is incorporated in these elements.

  The steering device 100B further includes an output unit 400B. The output unit 400B corresponds to the output unit 400 described with reference to FIG. The description regarding the output unit 400 may be incorporated into the output unit 400B.

  Similar to the second embodiment, the output unit 400 </ b> B includes a carrier 500. The description of the second embodiment is applied to the carrier 500.

  The output part 400B further includes an output shaft part 600B. Similar to the second embodiment, the output shaft portion 600B includes a mounting plate 610, a narrow detail 410A, and a connecting gear 420A. The description of the second embodiment is incorporated in these elements.

  The output shaft portion 600B further includes a shaft 430B. Similar to the second embodiment, the shaft 430 </ b> B includes a proximal end portion 431. The description of the second embodiment is incorporated in the base end portion 431. In the present embodiment, the rotating shaft is exemplified by the shaft 430B.

  The shaft 430B further includes a tip portion 432B. The output unit 400B further includes a pinion 433. The pinion 433 is attached to the tip portion 432B. Alternatively, the pinion 433 may be formed integrally with the tip 432B. The pinion 433 rotates around the output shaft OPA integrally with the shaft 430B. The distal end portion 432B and the pinion 433 correspond to the second connecting portion 430 described with reference to FIG.

  FIG. 4 shows the rack RCK that meshes with the pinion 433. The rack RCK is connected to wheels (not shown) of a vehicle (not shown). The rotation of the pinion 433 is converted into a linear motion of the rack RCK. The direction of the wheel is changed by the linear motion of the rack RCK.

  While the gear mechanism 300A is operating normally, the rotational force output by the motor 200A is amplified at a predetermined reduction ratio by the gear mechanism 300A and becomes a large steering force. The steering force is transmitted to the carrier 500 and the output shaft portion 600B. As a result, the rack RCK receives a large steering force from the pinion 433 and moves linearly.

  When the driver rotates the steering shaft STS with the gear mechanism 300A fixed, a rotational force is applied to the connecting gear 420A that meshes with the worm gear WMG at the lower end of the steering shaft STS. The rotational force applied to the connecting gear 420A twists the output shaft portion 600B. Since the narrow detail 410A has a specifically small cross-sectional area, the twist of the output shaft portion 600B results in the fracture of the narrow detail 410A. When the narrow details 410A are broken, the shaft 430B can rotate according to the rotational force applied to the connection gear 420A without being constrained by the gear mechanism 300A. As a result, the pinion 433 attached to the shaft 430B rotates around the output shaft OPA and can move the rack RCK linearly.

<Fourth embodiment>
The steering mechanism may have a clutch mechanism instead of the narrow details. In the fourth embodiment, an exemplary steering device having a clutch mechanism will be described.

  FIG. 5 is a schematic cross-sectional view of a steering device 100C of the fourth embodiment. The steering device 100C will be described with reference to FIGS. 1 and 5. The description of the second embodiment is applied to elements having the same reference numerals as those of the second embodiment.

  The steering device 100C includes a motor 200A, a gear mechanism 300A, a gear box cylinder 440, and main bearings 445 and 446. The description of the second embodiment is incorporated in these elements.

  The steering device 100C further includes an output unit 400C. The output unit 400C corresponds to the output unit 400 described with reference to FIG. The description regarding the output unit 400 may be incorporated into the output unit 400C.

  Similar to the second embodiment, the output unit 400 </ b> C includes a carrier 500. The description of the second embodiment is applied to the carrier 500.

  The output part 400C further includes an output shaft part 600C. Similar to the second embodiment, the output shaft portion 600C includes a shaft 430A and a connection gear 420A. The description of the second embodiment is incorporated in these elements.

  The output unit 400C further includes a clutch mechanism 410C. The clutch mechanism 410C corresponds to the release unit 410 described with reference to FIG. The description regarding the cancellation | release part 410 may be used for the clutch mechanism 410C.

  Clutch mechanism 410C includes a mounting portion 610C, two clutch plates 411, 412 and a plurality of springs 413. The attachment portion 610 </ b> C includes an attachment plate 611 and a holding cylinder 612. The mounting plate 611 is a disk-shaped part that comes into contact with the end surface of the substrate portion 511 (the end surface facing the end wall 319 of the third cylindrical portion 313). The center of the mounting plate 611 substantially coincides with the output shaft OPA. The mounting plate 611 is fixed to the end surface of the base plate portion 511 (the end surface facing the end wall 319 of the third tube portion 313) with a bolt BLT. Therefore, the mounting plate 611 can be separated from the carrier 500. The holding cylinder 612 is a substantially cylindrical portion that protrudes from the mounting plate 611 toward the end wall 319 of the third cylinder portion 313. The plurality of springs 413 are disposed in the holding cylinder 612. The clutch plate 411 disposed between the carrier 500 and the shaft 430 </ b> A is connected to the plurality of springs 413 in the holding cylinder 612. The plurality of springs 413 push the clutch plate 411 from the holding cylinder 612 along the output shaft OPA toward the end wall 319 of the third cylinder portion 313. At this time, the clutch plate 411 is partially accommodated in the holding cylinder 612. The holding cylinder 612 may be formed so as to restrain the rotation of the clutch plate 411 around the output shaft OPA. Therefore, the clutch plate 411 rotates together with the carrier 500. In the present embodiment, the first clutch plate is exemplified by the clutch plate 411.

  The clutch plate 412 is attached to the base end portion 431 of the shaft 430A. Therefore, the clutch plate 412 is located between the clutch plate 411 and the shaft 430A. The clutch plate 411 is pressed against the clutch plate 412 by a plurality of springs 413. In the present embodiment, the second clutch plate is exemplified by the clutch plate 412.

  If the load torque applied to shaft 430A does not exceed a predetermined threshold value, clutch plates 411 and 412 rotate integrally. When the load torque applied to the shaft 430A exceeds a predetermined threshold value, the clutch plate 412 is rotated independently of the clutch plate 411 by the steering force input to the connection gear 420A. Therefore, even if the gear mechanism 300A is fixed, the shaft 430A can rotate in accordance with the rotation of the steering shaft STS and can swing the pitman arm PTM.

  The design principles described in connection with the various embodiments described above are applicable to various steering devices. Some of the various features described in connection with one of the various embodiments described above may be applied to the steering apparatus described in connection with another embodiment.

  The principle of the above-described embodiment is preferably used for various vehicle designs.

100, 100A, 100B, 100C ... Steering device 200, 200A ... Motor 300, 300A ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Gear mechanism 310 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Outer cylinder 317 ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Internal tooth pin 320 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ Crank assemblies 331, 332 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Oscillating gears 400, 400A, 400B, 400C ...... Output section 410 ... release part 410A ... ... Narrow details 410C ... ... Clutch mechanism 411, 412 ... Clutch plate 420 ... ... the first connecting part 420A ... the connecting gear 430 ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 2nd connection part 430A, 430B ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ shaft 432 , 432B ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Tip 433 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Pinion 500 ... Carrier OPA ... .... Output shaft PTM ...・ Pitman Arm RCK ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Rack STM ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ Steering mechanism STS ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Steering shaft

Claims (8)

A motor that generates a rotational force according to the steering torque applied to the steering shaft;
A gear mechanism that amplifies the rotational force at a predetermined reduction ratio and generates a steering force;
An output unit for outputting the steering force to a steering mechanism connected to a wheel;
The output unit includes a transmission unit that transmits the steering force to the steering mechanism, and a release unit that releases a mechanical connection between the transmission unit and the gear mechanism,
The transmission unit is mechanically connected to the steering shaft and rotates around a predetermined rotation center axis so that the steering torque is reduced when the steering force is transmitted,
When the load torque generated in the transmission unit due to the rotation of the steering shaft under the fixing of the gear mechanism exceeds a threshold value, the release unit releases the mechanical connection,
When the release unit releases the mechanical connection, the transmission unit rotates around the rotation center axis and transmits the rotation of the steering shaft to the steering mechanism. The steering apparatus according to claim 1, wherein the transmission unit includes an output shaft unit having a first coupling unit coupled to the steering shaft and a second coupling unit coupled to the steering mechanism. The output shaft portion includes a rotation shaft extending along the rotation center axis,
The first connecting portion includes a connecting gear attached to the rotating shaft,
The steering apparatus according to claim 2, wherein the connection gear is connected to a steering gear that rotates together with the steering shaft. The output unit includes a carrier coupled to the gear mechanism and rotating around the rotation center axis,
The rotating shaft includes, as the release portion, a narrow detail having a specifically small cross section between the rotating shaft and the carrier,
The steering apparatus according to claim 3, wherein when the load torque exceeds the threshold value, the narrow details are broken. The gear mechanism includes an outer cylinder in which a plurality of internal teeth are formed, a rocking gear that meshes with the plurality of internal teeth, and a center of the rocking gear that circulates around the rotation center axis of the output unit. A crank assembly that imparts rocking rotation to the rocking gear,
The carrier is coupled to the crank assembly and rotates about the rotation center axis in the outer cylinder;
The steering apparatus according to claim 4, wherein the narrow details are accommodated in the outer cylinder. The output unit includes a carrier coupled to the gear mechanism and rotating around the rotation center axis,
The release portion includes a clutch mechanism disposed between the rotating shaft and the carrier,
The clutch mechanism includes a first clutch plate disposed between the carrier and the rotating shaft, and a second clutch plate disposed between the first clutch plate and the rotating shaft,
If the load torque does not exceed the threshold value, the first clutch plate and the second clutch plate rotate integrally,
When the load torque exceeds the threshold value, one of the first clutch plate and the second clutch plate rotates independently of the other of the first clutch plate and the second clutch plate. 3. The steering device according to 3. The second connection part includes a spline shaft part or a key structure part formed on the rotary shaft,
The steering apparatus according to any one of claims 3 to 6, wherein the turning mechanism includes a pitman arm attached to the spline shaft portion or the key structure portion. The second connecting portion includes a pinion that rotates integrally with the rotary shaft around the rotation center axis,
The steering apparatus according to claim 3, wherein the steering mechanism includes a rack that meshes with the pinion.

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