JP5483729B2 - Steer-by-wire steering device and vehicle equipped with the same - Google Patents

Description

  The present invention relates to a steer-by-wire steering device that is steered by a steering device that is mechanically separated from a steering input device such as a steering wheel, and a vehicle such as an automobile equipped with the steering device.

  2. Description of the Related Art Conventionally, a steer-by-wire type steering device realized by a ball screw mechanism and a link mechanism has been proposed (for example, Patent Document 1). According to the ball screw mechanism, since the frictional resistance is small, it is possible to use a high-speed low torque motor and reduce the drive motor by increasing the reduction ratio.

JP 2007-326459 A

When a ball screw mechanism in which the screw shaft advances and retreats is applied to the steered mechanism, a space in which the screw shaft can move is necessary, so that it is necessary to secure a space in the axle direction. Therefore, it is difficult to make the steering mechanism into a compact configuration that fits in the wheel house of the vehicle. From various demands, it is desired to place the steering mechanism in the wheel house of the vehicle. In particular, in an electric vehicle, it is necessary to install a battery, an inverter, or the like in a portion corresponding to an engine room of a gasoline vehicle to secure a wide space in the vehicle. Therefore, it is necessary to make the steering mechanism fit in the wheel house.
Moreover, since the conventional steer-by-wire type steering device uses a link mechanism as a steering mechanism, it is disadvantageous for downsizing, and wide-angle steering is difficult. In addition, there is a possibility that locking occurs during a full stroke.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steer-by-wire steering device and a vehicle that can realize wide-angle turning and have a compact configuration with an independent steering system in which steering of each wheel is made independent.

The steer-by-wire steering device of the present invention controls a steering input device, a steering device mechanically separated from the steering input device, and the steering device based on an input signal from the steering input device. In the steer-by-wire type steering device configured by the steering control device
The steered device is a steered actuator fixed to a steered wheel connecting member composed of a knuckle of a steered wheel or a member fixed thereto, a steered shaft fixed to an upper arm of a suspension, and the steered shaft as a center. A fixed gear fixed to the steered shaft as a shaft, a nut that meshes with the fixed gear and can move on the outer periphery of the fixed gear, and has a spiral groove of a spiral groove on the inner diameter surface, and the same as the spiral groove A shaft provided with a spiral groove of a spiral groove at a pitch, and a plurality of balls interposed between the nut and the shaft,
The fixed gear, the nut, the ball, and the shaft are housed in a gear case, the drive shaft of the steering actuator is coupled to the shaft, and the fixed gear is supported by a bearing through the gear case. The shaft is supported by the gear case via a bearing, and the gear case is fixed to the steered wheel connecting member.

According to this configuration, a fixed gear is fixed on the same axis as the steered shaft, and a nut formed with a gear is arranged on the outer peripheral surface so as to mesh with the nut. The nut circulates a plurality of balls through a spiral groove on the inner diameter surface, and the nut Is arranged so that it can rotate through the ball. The axis converts the rotational motion by the steering actuator into the linear motion of the nut. A gear case that covers the gear, nut, and shaft is fixed to a knuckle or a steered wheel connecting member that is fixed to the knuckle. For this reason, a steered wheel steers by the drive of a steering actuator.
As described above, since the ball nut mechanism in which the nut advances and retreats is used, it is made more compact in the axial direction than the ball screw mechanism that advances and retracts the screw shaft. Further, like the ball screw mechanism for moving the screw shaft back and forth, the frictional resistance is small, and by increasing the reduction ratio of the ball nut, the turning actuator can be made small by using a high speed low torque motor or the like.
In addition, a fixed gear is fixed on the same axis as the steered shaft, and the nut of the ball nut mechanism is provided so as to mesh with it. And wide-angle steering is possible. When the steering device is a link mechanism, there is a possibility that a lock may occur at the time of a full stroke, but the lock does not occur due to the steering by a gear.
Since the fixed gear and the ball nut mechanism are combined, it is possible to provide an independent steering system that is excellent in compactness and that makes each wheel steering independent.
As described above, an independent steering system in which the steering of each wheel is made independent can realize wide-angle turning and a compact configuration.

  In the present invention, a universal joint may be interposed between the upper arm and the fixed gear, which is located on the turning axis. If a universal joint is interposed between the upper arm and the fixed gear, the vehicle body can be allowed to tilt and torque can be transmitted. The universal joint is preferably a constant velocity joint because of its constant velocity. The constant velocity joint should be as small as possible for internal play.

  The steering actuator is preferably an electric motor in terms of controllability and energy supply. This motor may be a DC brushless motor with an angle sensor.

  The fixed gear may be a spur gear or a helical gear. The outer peripheral surface of the nut may be either a spur gear or a helical gear. Spur gears and helical gears are preferred because of the ability to transmit rotation and general-purpose products.

  In this invention, the shaft and the drive shaft of the steering actuator may be arranged in parallel, and the drive of the drive shaft may be transmitted to the shaft via a rotation transmission mechanism. The rotation transmission mechanism may be a gear train or a winding transmission mechanism such as a belt or a chain. If the shaft and the drive shaft of the steering actuator are arranged in parallel, the degree of freedom of the layout of the steering device is increased. Moreover, it can comprise compactly in an axial direction.

In this invention, the steered wheel connecting member may include a housing of an in-wheel motor device fixed to the knuckle.
By combining this steer-by-wire steering device with a configuration that enables wide-angle steering and an in-wheel motor device, for example, it is possible to run sideways while driving the vehicle in the forward direction, while rotating the vehicle. The radius can be reduced to enable in-situ rotation. Thereby, parking in a limited space can be easily performed.

  In the present invention, it is preferable that the surface of the spiral groove of the nut inner diameter surface and the shaft outer diameter surface is a surface-modified member. As the surface modification portion, for example, a material in which a sliding material such as PTFE (polytetrafluoroethylene) is dispersed in electroless Ni (nickel), a DLC (diamond-like carbon) film, or the like can be used. By this surface modification, smoothing due to a decrease in frictional resistance, reduction in wear due to hardening, and improvement in durability can be obtained.

  In this invention, the lower free end of the steered shaft is inserted into a recess provided in the steered wheel connecting member via a bearing member, and the steered wheel connecting member is connected to the steered shaft together with the steered wheel. It is good to contact in a rotatable manner. Thereby, friction and wear are suppressed, and the lower free end of the steered shaft can be supported without hindering the rotation of the steered shaft.

  The bearing member disposed at the contact portion of the lower free end of the steered shaft may be a thrust bearing, a ball joint, a thrust spherical bush, or a surface-modified sliding member. In the case of a thrust bearing, the resistance to rotation is small. In the case of a ball joint or thrust spherical bush, the tilt of the steered shaft can be freely allowed and supported. In the case of a surface-modified sliding member, a simple configuration is possible. Can support with low rotational resistance.

In the present invention, reverse input blocking means may be interposed between the drive shaft of the steering actuator and the shaft. The reverse input blocking means is, for example, a reverse input blocking clutch.
Since the ball nut mechanism including the nut and the ball is relatively efficient, the turning motor is turned by reverse input from the road surface. For this reason, position correction is required in order to maintain steering stability, and the motor power is consumed during that time. In order to suppress the power consumption, it is preferable to provide a reverse input prevention mechanism such as a clutch in the ball nut mechanism.

In this invention, it is preferable that the driving force of the steered actuator is transmitted to the shaft through a speed reducing unit. By using the decelerating means, a higher speed, low torque type steering actuator can be used, and the steering actuator can be downsized.
The reduction means may be a harmonic drive reducer, a cycloid reducer, or other low backlash reducer. According to the harmonic drive reducer and the cycloid reducer, a large reduction ratio can be obtained, the backlash is low, and the play at the time of changing the direction can be reduced. Other low backlash reducers can also reduce play when switching directions.

  A vehicle according to the present invention includes a steer-by-wire steering apparatus having any one of the above-described configurations according to the present invention. In this vehicle, the suspension type may be a double wishbone type.

The steer-by-wire steering device of the present invention controls a steering input device, a steering device mechanically separated from the steering input device, and the steering device based on an input signal from the steering input device. A steer-by-wire steering system comprising a steering control device, wherein the steered device is fixed to a steered wheel coupling member comprising a knuckle of a steered wheel or a member fixed thereto, and an upper of a suspension A steered shaft fixed to the arm, a fixed gear fixed to the steered shaft with the steered shaft as a central axis, and an outer periphery of the fixed gear that can mesh with the fixed gear and move to the inner diameter surface. A nut provided with a spiral groove, a shaft provided with a spiral groove of the spiral groove at the same pitch as the spiral groove, and a plurality of balls interposed between the nut and the shaft The fixed gear, the nut, the ball, and the shaft are housed in a gear case, a drive shaft of the steering actuator is connected to the shaft, and the fixed gear is connected to the gear case via a bearing. And the shaft is supported by the gear case via a bearing, and the gear case is fixed to the steered wheel connecting member. And a compact configuration.
Since the vehicle according to the present invention includes the steer-by-wire type steering apparatus according to the present invention, wide-angle steering can be realized by an independent steering system in which the steering of each wheel is made independent, and a compact configuration can be achieved.

It is explanatory drawing which shows schematic structure of the steer-by-wire type steering apparatus which concerns on one Embodiment of this invention, and the conceptual structure of the control system. It is a front view which shows the in-wheel motor and gear case periphery part of the steering apparatus. It is a front view which shows the knuckle and the gear case periphery part in the modification of the steering apparatus. It is a fracture front view showing the inside of the gear case and the turning shaft of the steering device. It is a fracture | rupture top view which shows the inside of the gear case of the same steering device, and a turning shaft. It is a fracture | rupture top view which shows the inside of the gear case and the turning shaft in the modification of the steering apparatus. It is an enlarged fracture top view which shows the peripheral part of the nut in the steering device. It is an expanded fracture front view which shows the support structure of the steering shaft lower end of the steering apparatus. It is an expanded fracture front view which shows the modification of the support structure of the steering shaft lower end of the steering apparatus. It is an enlarged fracture front view showing other modifications of the support structure of the lower end of the turning shaft of the steering device. It is an enlarged fracture front view showing other modifications of the support structure of the lower end of the turning shaft of the steering device. It is a partial expanded sectional view which shows the surface modification part in the nut and the helical groove | channel of a shaft of the same steering device. It is explanatory drawing which shows arrangement | positioning of the reverse input prevention mechanism of the steering apparatus. It is the schematic of the vehicle equipped with the steering device.

  An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the steer-by-wire steering device includes a steering input device 1 such as a steering wheel, a steering device 2 mechanically separated from the steering input device 1, and the steering input device. And a steering control device 3 that controls the steered device 2 based on an input signal from 1. The steered device 2 is provided for each steered wheel 4 on both sides in the vehicle width direction and constitutes an independent steering system. Each steered wheel 4 is supported by a chassis 6 via a suspension 5.

  A steering angle sensor 7 and a steering torque sensor 8 are provided for a steering input device 1 including a steering wheel, and a steering reaction force motor 9 is connected thereto. The steering angle sensor 7 is a sensor that detects a steering angle of the steering input device 1, and the steering torque sensor 8 is a sensor that detects torque that acts on the steering input device 1. The steering reaction force motor 9 is a motor that applies reaction force torque to the steering input device 1, monitors the input of the steering torque sensor 8 via torque control means (not shown), and determines a predetermined reaction force torque. give.

  The steering control device 3 is means for giving a drive command to the steering actuator 10 of each steering device 2 according to a predetermined rule according to the detected angle of the steering angle sensor 7. The steering actuator 10 is an electric motor, for example, a DC brushless motor with an angle sensor. The steering control device 3 is provided as a part of an ECU (electric control unit) 11 that controls the entire vehicle. The ECU 11 includes a computer, a program executed on the computer, and various electronic circuits.

  The suspension 5 is a mechanism for supporting the steered wheels 4 by an upper arm 5U and a lower arm 5L, and is, for example, a double wishbone type or a multi-link type. The double wishbone type is supported by two upper and lower V-shaped upper arms 5U and a lower arm 5L, and a coil spring and a shock absorber (both not shown) are provided between the upper arm 5U and the lower arm 5L. There is much to be done.

  As shown in an enlarged view in FIG. 2, the steered device 2 includes a steered actuator 10 fixed to the steered wheel connecting member 12 and a steered shaft 13 fixed to the upper arm 5 </ b> U of the suspension 5. A universal joint 15 is interposed on the steered shaft 13. The steered wheel connecting member 12 includes a knuckle 12a of the steered wheel 4 or a member fixed thereto. The term “fixed” as used herein includes the case of an integral member. The embodiment of FIG. 2 is a type in which the steered wheel 4 is driven by the in-wheel motor device 14, and the steered wheel coupling member 12 includes the knuckle 12 a and the housing 14 a of the in-wheel motor device 14. In this example, the in-wheel motor device 14 is an assembly part in which a motor, a speed reducer, and a wheel bearing are assembled in a common housing 14a. In addition to the wheel bearing, a part or the whole of the motor and the speed reducer. Is disposed in the steering wheel 4.

  FIG. 3 is an example in which the steered wheel 4 is a driven wheel, and the steered wheel coupling member 12 includes a knuckle 12 a that supports the steered wheel 4. The steered wheel connecting member 12 may have any of the configurations shown in FIGS. 2 and 3, and the following description will be made without distinguishing the examples of FIGS. 2 and 3, unless particularly required.

  As shown in FIG. 4 in a cutaway front view and in FIG. 5 in a cutaway plan view, the steered device 2 has a fixed gear 16 fixed to the steered shaft 13 with the steered shaft 13 as a central axis, and this fixed It has a nut 17 that meshes with the gear 16 by a gear 17 b on the outer peripheral surface and can move the outer periphery of the fixed gear 16 in a tangential direction, and a shaft 18 that is a ball screw shaft inserted through the nut 17. As shown in an enlarged view in FIG. 7, spiral grooves 17a and 18a having the same pitch as each other are provided on the inner peripheral surface of the nut 17 and the outer peripheral surface of the shaft 18, and between these spiral grooves 17a and 18a. A plurality of balls 19 are interposed. The nut 17, the shaft 18, and the plurality of balls 19 constitute a ball nut mechanism 20. The fixed gear 16 and the gear 17b on the outer periphery of the nut 17 may be either a spur gear or a helical gear.

  In FIG. 5, the fixed gear 16, the nut 17, the ball and the shaft 18 are housed in a gear case 21, and the drive shaft 10 a of the steered actuator 10 is connected to the shaft 18. In the case where the steered actuator 10 is a motor with a speed reducer that includes the motor 10A and a speed reducer 10B that decelerates the motor output, the drive shaft 10a is an axis that serves as an output shaft of the motor with the speed reducer. The shaft 18 is supported at both ends by a gear case 21 so as to be freely rotatable via rolling bearings 22, and the steering actuator 10 is fixed to the gear case 21. The drive shaft 10a of the steered actuator 10 and the shaft 18 are connected by a shaft coupling (not shown) such as a bush. The fixed gear 16 is supported via a bearing with respect to the gear case 21 and can freely rotate and move in the axial direction, but the steered shaft 13 to which the fixed gear 16 is fixed is connected to the gear case via the bearing 29. 21 is rotatably supported. As shown in FIGS. 2 and 3, the gear case 21 is fixed to the steered wheel connecting member 12 such as the knuckle.

  As shown in FIG. 6, the steering actuator 10 is arranged so that the drive shaft 10 a and the shaft 18 are parallel to each other, and the rotation of the drive shaft 10 a is transmitted to the shaft 18 via the rotation transmission mechanism 24. You may make it do. The rotation transmission mechanism 24 may be a gear train or a winding transmission mechanism such as a belt or a chain. If the shaft 18 and the drive shaft 10a of the steering actuator 10 are arranged in parallel as in this example, the degree of freedom in the layout of the steering device 2 is increased. Further, the axial length can be made compact.

  2 and 3, the universal joint 15 is interposed between the upper arm 5U and the fixed gear 16 shown in FIG. Specifically, as shown in FIG. 4, the steered shaft 13 is divided into an upper steered shaft 13 </ b> A and a lower steered shaft 13 </ b> B, and both shafts are connected by a universal joint 15. The universal joint 15 is a ball joint type constant velocity universal joint, an outer joint member 15a having a cup strip portion at one end of the lower turning shaft 13B, and an inner joint fixed to the outer periphery of the lower end of the upper turning shaft 13A. Material 15b, and a torque transmission ball 15c interposed between axial grooves provided on opposing circumferential surfaces of the outer joint member 15a and the inner joint member 15b. The axial grooves are provided at a plurality of locations in the circumferential direction, and the torque transmission balls 15c in each groove are held by a cage 15d. A bellows cover 15e is provided between the mouth of the cup portion of the outer joint member 15a and the outer periphery of the upper turning shaft 13A.

  FIG. 14 shows a vehicle 40 that is a four-wheeled vehicle and in which the steer-by-wire steering device of the embodiment of FIGS. 1 and 2 is installed on each wheel.

  Next, the operation and details of the configuration of the steer-by-wire steering device of this embodiment will be described. According to the steer-by-wire type steering apparatus having this configuration, the fixed gear 16 is fixed on the same axis as the steered shaft 13 as shown in FIG. Circulates a plurality of balls 19 in a spiral groove 17 b on the inner surface, and a shaft 18 is arranged in a state where the nut 17 can rotate through the balls 19. The shaft 18 converts the rotational motion by the steering actuator 10 into the linear motion of the nut. A gear case 21 covering the fixed gear 16, the nut 17 and the shaft 18 is fixed to the steered wheel connecting member 12 such as a knuckle 12a. For this reason, the steered wheels 4 are steered by driving the steered actuator 10.

As described above, since the ball nut mechanism 20 in which the nut 17 is advanced and retracted is used, it is made more compact in the axial direction than the ball screw mechanism in which the screw shaft is advanced and retracted. Further, like the ball screw mechanism for moving the screw shaft back and forth, the frictional resistance is small, and by increasing the reduction ratio of the ball nut mechanism 20, a high-speed low torque motor or the like is used as the turning actuator 10, and the turning actuator 10 is made small. Is possible.
Further, the fixed gear 16 is fixed on the same axis as the steered shaft 13, and the nut 17 of the ball nut mechanism 20 is provided so as to mesh with the steered shaft 13, and the gears 16 and 17b are steered. Compared to the rudder device, it can be configured more compactly, and wide-angle steering is possible. For example, a steering angle of 90 ° is possible. When the steering device is a link mechanism, there is a possibility that a lock may occur at the time of a full stroke, but the lock does not occur due to the steering by the gears 16 and 17b.
Since the fixed gear 16 and the ball nut mechanism 20 are combined, the structure is excellent in compactness, and an independent steering system in which the steering of each steered wheel 4 is made independent is possible.
As described above, an independent steering system in which the steering of each wheel is made independent can realize wide-angle turning and a compact configuration.

  Further, since the universal joint 15 is interposed between the upper arm 5U and the fixed gear 16 on the turning axis O, it is possible to allow the vehicle body to tilt and transmit torque.

  In the embodiment of FIG. 2, the in-wheel motor device 14 is used for the steered wheel 5, and the housing 14 a of the in-wheel motor device 14 is included in the steered wheel connecting member 12. In the embodiment shown in the figure, since the in-wheel motor device 14 is combined with a configuration capable of 90 ° wide-angle steering by this steer-by-wire steering device, for example, as shown in FIG. While running toward A, it is possible to run in the transverse direction B, which is the orthogonal direction. Further, the rotation radius can be reduced to enable in-situ rotation. Thus, parking in a limited space can be easily performed.

  In the embodiment shown in FIGS. 1 to 7, as shown in FIG. 12, the surface portions 17aa and 18aa of the spiral grooves 17a and 18a (FIG. 7) of the inner diameter surface of the nut 17 and the outer diameter surface of the shaft 18 are provided. (FIG. 12) may be a surface-modified member. In the illustrated example, not only the inner surfaces of the spiral grooves 17a and 18a, but also the surface portion between adjacent spiral portions of the spiral grooves 17a and 18a is used as the surface modification portion. As the surface modification portion, for example, a material in which a sliding material such as PTFE is dispersed in electroless Ni, a DLC (diamond-like carbon) film, or the like can be used. By this surface modification, it becomes a countermeasure against friction and wear, and smoothing due to reduction in sliding resistance, reduction in wear due to hardening, and improvement in durability can be obtained.

  As shown in FIG. 8, the lower free end 13 a of the steered shaft 13 is inserted into a recess 23 provided in the steered wheel connecting member 12 via a bearing member 24, and the steered wheel connecting member 12 is turned into the steered wheel 4. At the same time, it may be in contact with the turning shaft 13 so as to be rotatable. Thereby, the lower free end 13a of the steered shaft 13 can be supported without disturbing the rotation of the steered shaft 13.

  The bearing member 24 arranged at the contact portion of the lower free end 13a of the steered shaft 13 may be a thrust bearing as shown in FIG. The thrust bearing shown in the figure is composed of a roller with a cage in which a plurality of rollers 25 arranged in the circumferential direction are held by a cage 26. When the bearing member 24 is a rolling thrust bearing, the rotational resistance is small.

In addition to this, the bearing member 24 arranged at the lower free end 13a of the steered shaft 13 may be a ball joint 24A as shown in FIG. 9, a thrust spherical bush 24B as shown in FIG. As shown, the surface-modified disk slide member 24C may be used. Also in this case, the surface modification can be performed using, for example, a material in which a sliding material such as PTFE is dispersed in electroless Ni, a DLC (diamond-like carbon) film, or the like.
When the bearing member 24 is a ball joint or a thrust spherical bush, the tilt of the steered shaft 13 can be freely allowed and supported. In the case where the bearing member 24 is a sliding member whose surface has been modified, it can be supported with a simple structure and low rotational resistance.

In each of the embodiments shown in FIGS. 1 to 11, for example, as shown in FIG. 13, a reverse input blocking means 30 may be interposed between the drive shaft 10a of the steering actuator 10 such as a motor and the shaft 18. . The reverse input blocking means 30 may be a reverse input blocking clutch such as a one-way clutch.
Since the ball nut mechanism 20 including the nut 17 and the ball 19 (FIG. 7) is relatively efficient, the turning actuator 10 is turned by reverse input from the road surface. Therefore, in order to maintain steering stability, position correction is required, and during that time, power of the steering actuator 10 composed of a motor is consumed. By providing the ball nut mechanism 20 with the reverse input prevention mechanism 30 such as the clutch, rotation due to reverse input from the road surface is prevented, and power consumption for coping with reverse input can be suppressed.

  In each embodiment shown in FIGS. 1 to 13, the driving force of the steering actuator 10 may be transmitted to the shaft 18 via a speed reducer 10 </ b> B as speed reduction means, as shown in FIG. 5. By using the speed reducer 10B, a higher speed, low torque type steering actuator can be used, and the steering actuator 10 is downsized. The reducer 10B may be a harmonic drive reducer, a cycloid reducer, or other low backlash reducer. According to the harmonic drive reducer and the cycloid reducer, a large reduction ratio can be obtained, the backlash is low, and the play at the time of changing the direction can be reduced. Other low backlash reducers can also reduce play when switching directions.

The vehicle 40 (FIGS. 1 and 14) according to this embodiment includes a steer-by-wire steering device having a configuration according to any one of the above embodiments. In the vehicle 40, the type of the suspension 5 may be a double wishbone type as described above.
According to the vehicle 40 having this configuration, the steering device 2 can achieve wide-angle turning and a compact configuration with an independent steering system in which the steering of each wheel is made independent.

DESCRIPTION OF SYMBOLS 1 ... Steering input device 2 ... Steering device 3 ... Steering control device 4 ... Steering wheel 5 ... Suspension 5U ... Upper arm 5L ... Lower arm 6 ... Chassis 10 ... Steering actuator 10a ... Drive shaft 10A ... Reduction gear (deceleration means)
DESCRIPTION OF SYMBOLS 12 ... Steering wheel connection member 12a ... Knuckle 13 ... Steering shaft 13a ... Lower free end 14 ... In-wheel motor apparatus 14a ... Housing 15 ... Universal joint 16 ... Fixed gear 17 ... Nut 17a ... Spiral groove 17b ... Gear 18 ... Shaft 18a ... spiral grooves 17aa, 18aa ... surface portion 19 ... ball 20 ... ball nut mechanism 21 ... gear case 23 ... recess 24 ... bearing member 28 ... rotation transmission mechanism 29 ... bearing 31 ... speed reducer (speed reduction means)
40 ... Vehicle

Claims (21)

A steering input device, a steering device mechanically separated from the steering input device, and a steering control device that controls the steering device based on an input signal from the steering input device. In the by-wire type steering device,
The steered device is a steered actuator fixed to a steered wheel connecting member composed of a knuckle of a steered wheel or a member fixed thereto, a steered shaft fixed to an upper arm of a suspension, and the steered shaft as a center. A fixed gear fixed to the steered shaft as a shaft, a nut that meshes with the fixed gear and can move on the outer periphery of the fixed gear, and has a spiral groove of a spiral groove on the inner diameter surface, and the same as the spiral groove A shaft provided with a spiral groove of a spiral groove at a pitch, and a plurality of balls interposed between the nut and the shaft,
The fixed gear, the nut, the ball, and the shaft are housed in a gear case, the drive shaft of the steering actuator is coupled to the shaft, and the fixed gear is supported by a bearing through the gear case. And the shaft is supported by the gear case through a bearing, and the gear case is fixed to the steered wheel connecting member.   The steer-by-wire steering apparatus according to claim 1, wherein the steer-by-wire steering apparatus is located on the turning axis, and a universal joint is interposed between the upper arm and the fixed gear.   The steer-by-wire steering device according to claim 2, wherein the shaft coupling is a constant velocity universal joint.   The steer-by-wire type steering apparatus according to any one of claims 1 to 3, wherein the turning actuator is a motor.   The steer-by-wire steering apparatus according to claim 4, wherein the motor is a DC brushless motor with an angle sensor.   6. The steer-by-wire steering apparatus according to claim 1, wherein the fixed gear is one of a spur gear and a helical gear.   The steer-by-wire steering device according to any one of claims 1 to 6, wherein an outer peripheral surface of the nut is either a spur gear or a helical gear.   The steer-by-wire system according to any one of claims 1 to 7, wherein the shaft and the drive shaft of the steering actuator are arranged in parallel, and the drive of the drive shaft is transmitted to the shaft via a rotation transmission mechanism. Steering device.   The steer-by-wire steering device according to any one of claims 1 to 8, wherein the steered wheel connecting member includes a housing of an in-wheel motor device fixed to the knuckle.   The steer-by-wire type steering device according to any one of claims 1 to 9, wherein the surface of the spiral groove on the inner surface of the nut and the outer surface of the shaft is a surface-modified member.   11. The lower free end of the steered shaft is inserted into a recessed portion provided in the steered wheel coupling member via a bearing member, and the steered wheel coupling member is A steer-by-wire type steering device that is in contact with the steered shaft together with the steered wheel so as to be rotatable.   The steer-by-wire steering apparatus according to claim 11, wherein the bearing member is a thrust bearing.   The steer-by-wire steering apparatus according to claim 11, wherein the bearing member is a ball joint.   The steer-by-wire steering apparatus according to claim 11, wherein the bearing member is a thrust spherical bush.   The steer-by-wire steering device according to claim 11, wherein the bearing member is a sliding member having a surface modified.   The steer-by-wire type steering apparatus according to any one of claims 1 to 15, wherein reverse input blocking means is interposed between the drive shaft of the steering actuator and the shaft.   The steer-by-wire steering device according to claim 16, wherein the reverse input blocking means is a reverse input blocking clutch.   The steer-by-wire steering device according to any one of claims 1 to 15, wherein a driving force of the steering actuator is transmitted to the shaft via a speed reduction unit.   The steer-by-wire steering apparatus according to claim 18, wherein the speed reduction means is a harmonic drive speed reducer, a cycloid speed reducer, or another low backlash speed reducer.   A vehicle comprising the steer-by-wire steering device according to any one of claims 1 to 19. The vehicle according to claim 21, wherein a type of the suspension is a double wishbone type.

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