JP2021084501A - Hub unit with steering function and vehicle equipped with the same - Google Patents

Abstract

To provide a hub unit with a steering function and a vehicle equipped with the same that can take an optimal steering angle and prevent deterioration of riding comfort due to increase of an unsprung load and further can reduce modifications at the vehicle side and reduce adjustment man-hours or the like during assembly.SOLUTION: A hub unit 1 with a steering function is a hub unit with a steering function configured to steer a rear wheel. The hub unit includes: a hub unit body 2 including a hub bearing 15 supporting the rear wheel; a unit support member 3 disposed at an unsprung portion of a rigid axle suspension Rs that is disposed in a vehicle body and supporting the hub unit body 2 such that the hub unit body is rotatable around a turning axis extending in vertical direction; and a steering actuator 5 configured to drive the hub unit body 2 such that the hub unit body rotates around the turning axis. The steering actuator 5 is disposed in the vehicle body 10a.SELECTED DRAWING: Figure 1

Description

The present invention relates to a hub unit with a steering function having a function of steering the left and right rear wheels and a vehicle equipped with the hub unit, and improves fuel efficiency by controlling the left and right rear wheels to an appropriate steering angle according to a driving situation. And the technology to stabilize the running performance and improve the safety.

Patent Documents 1 and 2 have been proposed as examples of the rear wheel steering mechanism.
In Patent Document 1, the steering actuator is attached on the spring (on the vehicle body side). Patent Document 1 is a mechanism in which left and right tires are connected by an arm and a ball joint using a watt link, and the rear wheels can be steered in the same phase.

In Patent Document 2, the steering actuator is attached under the spring (torsion beam). By arranging the steering actuator along the trailing arm (torsion beam) in the front-rear direction of the vehicle, it is possible to avoid interference with other parts such as the fuel tank or silencer, and for steering near the mounting part with the vehicle body. By attaching an actuator, it is possible to suppress changes in the toe angle due to vertical movement of the tire.

Japanese Unexamined Patent Publication No. 2019-9392 Japanese Patent No. 4966273

When the mechanism of Patent Document 1 is attached to an existing vehicle, the change on the vehicle side is large and it is difficult to standardize it. Further, since the left and right wheels are connected by the arm, the alignment adjustment becomes complicated.
In addition, it is difficult to control the right steering and the left steering because the angles are slightly different. Further, since there is only one steering actuator, left and right independent control cannot be performed.
In Patent Documents 1 and 2, since the kingpin shaft (steering shaft) is tilted, steering is performed while lifting the vehicle body, which requires a large amount of power. In addition, the tire house becomes larger because the rotation locus of the tire becomes larger.

The hub unit with steering function (Japanese Patent Application No. 2018-183189) proposed by the applicant can be mounted on a rigid axle such as a torsion beam, and the steering angle can be controlled largely and separately. However, the unit weight increases because the steering actuator is integrated. Since the hub unit with steering function is mounted on the torsion beam (unsprung), it may affect the ride quality.
In addition, since the hub unit with steering function is mounted on the tip (unsprung) of the torsion beam, it is easily affected by the road surface such as bouncing, and there is a problem that the power line and the connector part are repeatedly loaded. It is necessary to take measures such as strengthening the above.

An object of the present invention is to be able to take an optimum steering angle, prevent deterioration of riding comfort due to an increase in unsprung load, reduce changes on the vehicle side, and reduce adjustment man-hours at the time of assembly. It is to provide a hub unit with a steering function capable of capable of steering and a vehicle equipped with the hub unit.

The hub unit with a steering function of the present invention is a hub unit with a steering function that steers the rear wheels.
A hub unit body having a hub bearing that supports the rear wheels, and
A unit support member provided under the spring of the rear wheel suspension installed on the vehicle body and rotatably supporting the hub unit body around the center of the steering axis extending in the vertical direction.
A steering actuator that rotationally drives the hub unit body around the steering axis, and
With
The steering actuator is arranged above the spring of the vehicle body or the rear wheel suspension.
The upper part of the spring of the rear wheel suspension is a portion above the spring of the rear wheel suspension, and is referred to as a "spring upper part".

According to this configuration, the hub unit main body having the hub bearing that supports the rear wheels can be freely rotated around the steering axis center by driving the steering actuator. Therefore, it is possible to take the optimum steering angle. This makes it possible to improve the kinetic performance of the vehicle and to drive stably and safely. In addition, it is possible to improve fuel efficiency by setting an appropriate tire angle according to the driving conditions.
Since the steering actuator is arranged above the spring of the vehicle body or the rear wheel suspension, the influence on the ride quality can be reduced without increasing the unsprung weight. Further, since the steering actuator is arranged above the spring of the vehicle body or the rear wheel suspension, the wiring such as the power line or the sensor line extending from the steering actuator is bent as compared with the case where the steering actuator is arranged under the spring. Since there is no such thing, wiring and the like can be simplified, and handling and fixing can be easily performed. Therefore, the durability of the wiring and the like can be easily ensured, and the man-hours for the fixing work of the wiring and the like can be reduced.

By the way, in a normal vehicle, the rear wheels do not have a steering shaft, and in order to steer the rear wheels, it is necessary to newly provide a steering shaft in the suspension structure. The present invention includes a unit support member that rotatably supports the hub unit main body around the steering shaft center different from the wheel rotation shaft, and the hub unit main body is rotationally driven around the steering shaft center by a steering actuator. It is possible. As a result, the hub unit with a steering function can be easily installed in an existing vehicle without significantly changing the undercarriage structure of the vehicle, and the man-hours for alignment adjustment at the time of assembly can be reduced.

The steering actuator has a motor and a linear motion mechanism that converts the rotational output of the motor into a linear motion of the output rod, and when the output rod advances and retreats, the hub unit main body becomes the steering axis. It may be rotationally driven around. By advancing and retreating the output rod of the linear motion mechanism in this way, the hub unit main body is rotationally driven around the center of the steering shaft to be steered.

The linear motion mechanism and the hub unit main body may be connected via a ball joint. By using the ball joint in this way, it is not necessary to align the mounting heights of the output rod of the linear motion mechanism and a part of the hub unit main body connected to this output rod, and the steering actuator and the hub unit main body do not need to be aligned. The distance to and can be set arbitrarily. Since the mounting height of the steering actuator and the distance of the steering actuator to the hub unit body can be freely changed in this way, the degree of freedom in mounting the steering actuator on the vehicle is increased.

The left and right rear wheels may be steered by one steering actuator. In this case, the number of parts can be reduced and the structure can be simplified as compared with the configuration in which the left and right rear wheels are steered by two steering actuators. However, in this case, the steering angles of the left and right rear wheels are controlled in the same phase.

The hub unit main body is supported by the unit support member via rolling bearings at two upper and lower positions so as to be rotatable around the steering axis center, and the upper and lower rolling bearings are located in the wheels of the rear wheels. You may. In this case, the vehicle can be easily equipped with a hub unit with a steering function that has high rigidity and can be miniaturized. Therefore, since the existing vehicle can be easily equipped with the hub unit with the steering function, the versatility of the hub unit with the steering function can be enhanced.

The steering system of the present invention is a steering system including the hub unit with a steering function according to any one of the above and a control device for controlling a steering actuator of the hub unit with a steering function. , A steering control unit that outputs a current command signal corresponding to a given steering angle command signal, and an actuator that outputs a current corresponding to the current command signal input from the steering control unit to drive and control the steering actuator. It has a drive control unit.

According to this configuration, the steering control unit outputs a current command signal corresponding to a given steering angle command signal. The actuator drive control unit drives and controls the steering actuator by outputting a current corresponding to the current command signal input from the steering control unit. Therefore, the steering angle of the rear wheels can be arbitrarily changed in addition to the steering of the front wheels by the operation of the steering input unit of the driver.

The vehicle of the present invention is a vehicle in which the rear wheels are supported by using the hub unit with a steering function according to any one of the above, and the rear wheel suspension is a torsion beam type suspension. When trying to steer the rear wheels with a torsion beam suspension, which is often used as a suspension device that saves space and secures vehicle space, the steering shaft is compactly integrated with the hub bearing. It is possible to take advantage of the features of this hub unit with steering function. A hub unit with a steering function can be easily installed on the existing torsion beam suspension without major structural changes.

The hub unit with a steering function of the present invention is a hub unit with a steering function that steers the rear wheels, and has a hub unit body having a hub bearing that supports the rear wheels and a spring lower portion of the rear wheel suspension installed on the vehicle body. A unit support member provided in the above to rotatably support the hub unit main body around the steering shaft center extending in the vertical direction, and a steering actuator for rotationally driving the hub unit main body around the steering shaft center. The steering actuator is arranged above the spring of the vehicle body or the rear wheel suspension. Therefore, the optimum steering angle can be taken, the deterioration of the riding comfort due to the increase in the unsprung load can be prevented, the change on the vehicle side can be reduced, and the adjustment man-hours at the time of assembly can be reduced.

The steering system of the present invention is a steering system including the hub unit with a steering function according to any one of the above and a control device for controlling a steering actuator of the hub unit with a steering function. , A steering control unit that outputs a current command signal corresponding to a given steering angle command signal, and an actuator that outputs a current corresponding to the current command signal input from the steering control unit to drive and control the steering actuator. It has a drive control unit. Therefore, the optimum steering angle can be taken, the deterioration of the riding comfort due to the increase in the unsprung load can be prevented, the change on the vehicle side can be reduced, and the adjustment man-hours at the time of assembly can be reduced.

The vehicle of the present invention is a vehicle in which the rear wheels are supported by using the hub unit with a steering function according to any one of the above, and the rear wheel suspension is a torsion beam type suspension, so that an optimum steering angle can be obtained. It can be adopted, and it is possible to prevent deterioration of riding comfort due to an increase in unsprung load, and it is possible to reduce changes on the vehicle side and reduce adjustment man-hours at the time of assembly.

It is a perspective view which shows the whole appearance when the hub unit with a steering function which concerns on 1st Embodiment of this invention is mounted on a vehicle. It is a side view of the hub unit with a steering function. FIG. 2 is a sectional view taken along line III-III of FIG. It is a perspective view which shows the whole appearance when the hub unit with a steering function which concerns on another Embodiment of this invention is mounted on a vehicle. It is a top view when the hub unit with a steering function is mounted on a vehicle. It is a side view when the hub unit with a steering function is mounted on a vehicle. FIG. 6 is a sectional view taken along line VII-VII of FIG. It is a schematic plan view of the vehicle provided with any of the hub units with a steering function. It is a perspective view which shows the whole appearance when the hub unit with a steering function which concerns on still another Embodiment of this invention is mounted on a vehicle. It is a schematic plan view of the vehicle provided with the hub unit with the steering function. It is a schematic diagram when the hub unit with a steering function which concerns on still another Embodiment of this invention is mounted on a vehicle.

[First Embodiment]
A hub unit with a steering function according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3 and 8. The hub unit 1 with a steering function according to the embodiment has a function of independently steering each of the left and right rear wheels, and is applied to the rear wheels 9R and 9R of the vehicle 10 with front wheel steering as shown in FIG. Will be done.

<Outline structure of hub unit with steering function>
As shown in FIGS. 1 and 3, the hub unit 1 with a steering function includes a hub unit main body 2, a unit support member 3, a rolling bearing 4 which is a rotation allowable support component, and a steering actuator 5. A unit support member 3 is provided below the spring of the rear wheel suspension, which will be described later. As shown in FIG. 8, the vehicle 10 equipped with the hub unit 1 with a steering function steers the left and right front wheels 9F and 9F by operating the steering wheel and the like, and also steers the left and right rear wheels 9R and 9R at a minute angle (about ± 5 deg). ) It can be steered independently. However, in the hub unit 1 with a steering function, depending on the demand of vehicle control, the left and right wheels may individually take a relatively large angle such as 10 ° to 20 °, not limited to the minute angle.

As shown in FIGS. 1 and 3, the hub unit main body 2 is provided on the outboard side of the unit support member 3. With the hub unit 1 with steering function mounted on the vehicle 10 (FIG. 8), the outside of the vehicle 10 (FIG. 8) in the vehicle width direction is referred to as the outboard side, and the center side of the vehicle 10 (FIG. 8) in the vehicle width direction is referred to as the outboard side. It is called the inboard side.
The hub unit main body 1 is supported by a unit support member 3 via rolling bearings 4 and 4 at two upper and lower positions so as to be rotatable around a steering axis A extending in the vertical direction. The steering axis A is an axis different from the rotation axis O of the rear wheel 9R. The rear wheel 9R includes a wheel 9a and a tire 9b.

<Installation location of steering actuator 5>
The steering actuator 5 is fixed to the bracket Bk of the vehicle body (on the spring) 10a, and the hub unit main body 2 and the output rod 25a of the steering actuator 5 are connected via a ball joint Bj. By using the ball joint Bj, it is not necessary to align the mounting heights of the steering actuator 5 and the arm portion 17 of the hub unit main body 2, and the distance between the steering actuator 5 and the hub unit main body 2 can be arbitrarily set. .. Since the mounting height of the steering actuator 5 and the distance of the steering actuator 5 to the hub unit main body 2 can be freely changed in this way, the degree of freedom in mounting the steering actuator 5 on the vehicle is increased.
Further, the toe angle can be adjusted according to the length of the ball joint Bj and the position of the steering actuator 5 at the time of mounting. Normally, boots (not shown) are attached around the ball joint Bj for waterproof and dustproof purposes.

<Installation location of unit support member 3>
As shown in FIGS. 1 and 8, the unit support member 3 is fixed to the lower part of the spring of the rigid axle suspension Rs, which is the rear wheel suspension in the vehicle 10. In this example, the torsion beam type suspension of the rigid axle suspension Rs is applied. The unit support members 3 are fixed to the mounting portions 34 and 34 provided at both left and right ends of the beam 33 in the torsion beam type suspension, respectively. Although not shown, as a rear wheel suspension type, the unit support member 3 of the hub unit 1 with a steering function may be fixed to another suspension mechanism such as a multi-link suspension mechanism.

<About hub unit body 2>
As shown in FIGS. 1 and 3, the hub unit main body 2 includes a hub bearing 15 that supports the rear wheels 9R, an outer ring 16, and an arm portion 17 that is a steering force receiving portion. The hub bearing 15 has an inner ring 18, an outer ring 19, and a rolling element 20 such as a ball interposed between the inner and outer rings 18 and 19, and serves to connect a member on the vehicle body side and the rear wheel 9R. ..

In the illustrated example, the hub bearing 15 is an angular contact ball bearing in which the outer ring 19 is a fixed wheel, the inner ring 18 is a rotating wheel, and the rolling elements 20 are in a double row. The inner ring 18 has a hub ring portion 18a having a hub flange 18aa and forming a raceway surface on the outboard side, and an inner ring portion 18b forming a raceway surface on the inboard side. The wheel 9a of the rear wheel 9R is bolted to the hub flange 18aa so as to overlap the brake rotor 21a. The inner ring 18 rotates about the rotation axis O.

The outer ring 16 has an annular portion 16a fitted to the outer peripheral surface of the outer ring 19 and trunnion shaft-shaped mounting shaft portions 16b and 16b provided so as to project vertically from the outer circumference of the annular portion 16a. Each mounting shaft portion 16b is provided coaxially with the steering shaft center A.
The brake has a brake rotor 21a and a brake caliper (not shown). The brake caliper is attached to the upper and lower brake caliper mounting portions 22 formed integrally with the outer ring 19 so as to project in an arm shape.

<Rotation allowable support parts and unit support members>
As shown in FIG. 3, as the rolling bearing 4 which is each rotation allowable support component, a tapered roller bearing is applied in this example. The rolling bearing 4 has an inner ring fitted to the outer periphery of the mounting shaft portion 16b, an outer ring fitted to the unit support member 3, and a plurality of rolling elements interposed between the inner and outer rings. The upper and lower rolling bearings 4 and 4 are provided so as to be located in the wheel 9a. Fitting holes for fitting and fixing the outer ring 4b are formed in the upper and lower portions of the unit support member 3, and the outer ring 4b is fitted and fixed in each fitting hole. Each of the fitting holes is provided coaxially with the steering axis A.

Each mounting shaft portion 16b of the outer ring 16 is formed so that a female screw portion extends in the radial direction, and a bolt 23 screwed into the female screw portion is provided. A disk-shaped pressing member 24 is interposed on the end face of the inner ring, and a pressing force is applied to the end face of the inner ring by a bolt 23 screwed into the female screw portion to give a preload to each rolling bearing 4. There is. As a result, the rigidity of each rolling bearing 4 can be increased. Even if the weight of the vehicle acts on the hub unit 1, the initial preload is set so as not to come off. Therefore, the hub unit 1 with a steering function can secure the rigidity as a steering device. The rolling bearing 4 is not limited to the tapered roller bearing, and an angular contact ball bearing may be used depending on the usage conditions such as the maximum load. In that case as well, a preload can be applied in the same manner as described above.

As shown in FIGS. 1 and 3, the arm portion 17 is a portion serving as an action point for applying a steering force to the outer ring 19 of the hub bearing 15, and is fixed to the brake caliper mounting portion 22 by, for example, welding, bolts, or the like, or the brake caliper. It is integrally provided on the mounting portion 22. The arm portion 17 projects from the inboard side end surface of the brake caliper mounting portion 22 toward the inboard side by a predetermined length. Holes 3a and 34a are formed in the unit support member 3 and the suspension mounting portion 34 to allow the arm portion 17 to protrude toward the inboard side and prevent interference with the arm portion 17. The arm portion 17 is rotatably connected to an output rod 25a, which is a linear output portion of the steering actuator 5, via the ball joint Bj. By advancing and retreating the output rod 25a of the steering actuator 5, the hub unit main body 2 is rotated, that is, steered around the steering axis A.

<Steering actuator 5>
By separating the steering actuator 5 from the hub unit main body 2, a drive shaft (not shown) can be arranged on the hub wheel portion 18a of the hub bearing 15, so that the hub unit 1 with a steering function can be used as a rear wheel drive vehicle. Can also be installed.
In the steering actuator 5 of this example, one side surface of the actuator body is fixed to the bracket Bk so that the actuator body extends in the front-rear direction of the vehicle. The steering actuator 5 includes a motor 26 and a linear motion mechanism 25, but a speed reducer (not shown) that reduces the rotational output of the motor 26 may be interposed. The motor 26 is, for example, a permanent magnet type synchronous motor, but may be a DC motor or an induction motor.

The linear motion mechanism 25 converts the forward and reverse rotational output of the motor 26 into a reciprocating linear operation of the output rod 25a. As the linear motion mechanism 25, a feed screw mechanism such as a sliding screw or a ball screw, a rack pinion mechanism, or the like can be used, and in this example, a feed screw mechanism using a trapezoidal sliding screw is used. Since the linear motion mechanism 25 is a feed screw mechanism using the slip screw of the trapezoidal screw, the effect of preventing reverse input from the tire 9b can be enhanced.

<Effect>
According to the hub unit 1 with a steering function described above, the hub unit main body 2 having the hub bearing 15 supporting the rear wheel 9R is freely rotated around the steering axis A by driving the steering actuator 5. Can be done. Therefore, it is possible to take an optimum steering angle, and for example, the steering angle of the rear wheels 9R can be arbitrarily controlled according to the traveling condition of the vehicle 10. For example, if the steering angle of the rear wheels 9R is set to the same phase as that of the front wheels 9F, yaw generated in the vehicle 10 during steering can be suppressed and the stability of the vehicle 10 can be improved. Further, by adjusting the steering angle independently on the left and right even when traveling in a straight line, the traveling stability of the vehicle 10 can be ensured.

Since the steering actuator 5 is arranged on the vehicle body (on the spring) 10a, the influence on the riding comfort can be reduced without increasing the unsprung weight. Further, since the steering actuator 5 is arranged on the vehicle body 10a, the wiring Wr (FIG. 2) such as the power line or the sensor line extending from the steering actuator 5 is bent as compared with the case where the steering actuator is arranged under the spring. Since there is no need to do so, wiring and the like can be simplified, and handling and fixing can be easily performed using a clamp Kp (FIG. 2) or the like. Therefore, the durability of the wiring and the like can be easily ensured, and the man-hours for the fixing work of the wiring and the like can be reduced.

By the way, in a normal vehicle, the rear wheels do not have a steering shaft, and in order to steer the rear wheels, it is necessary to newly provide a steering shaft in the suspension structure. The hub unit 1 with a steering function includes a unit support member 3 that rotatably supports the hub unit body 2 around a steering axis A different from the wheel rotation axis, and the hub unit body 2 is supported by a steering actuator 5. It can be rotationally driven around the steering axis A. As a result, the hub unit 1 with a steering function can be easily installed in the existing vehicle 10 without significantly changing the undercarriage structure of the vehicle 10, and the adjustment man-hours at the time of assembly can be reduced. .. Further, the steering angle of the tire 9b attached to the hub unit main body 2 can be arbitrarily changed independently on the left and right with a simple structure while ensuring the rigidity only by attaching the hub unit 1 with a steering function.

The hub unit main body 2 is supported by the unit support member 3 via rolling bearings 4 and 4 at two upper and lower positions so as to be rotatable around the steering axis A, and the upper and lower rolling bearings 4 and 4 are rear wheels 9R. It is located in the wheel 9a of. Therefore, the vehicle 10 can be easily equipped with the hub unit 1 with a steering function, which has high rigidity and can be miniaturized. Therefore, since the existing vehicle 10 can be easily equipped with the hub unit 1 with a steering function, the versatility of the hub unit 1 with a steering function can be enhanced.

<About other embodiments>
In the following description, the same reference numerals will be given to the parts corresponding to the matters previously described in each embodiment, and duplicate description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described above unless otherwise specified. It produces the same action and effect from the same configuration. Not only the combination of the parts specifically described in each embodiment, but also the combinations of the embodiments can be partially combined as long as the combination does not cause any trouble.

As shown in FIGS. 4 to 7, each steering actuator 5 may be arranged on the vehicle body (on the spring) 10a so that the actuator main body extends in the left-right direction of the vehicle. The steering actuator 5 for the left rear wheel is provided above the beam 33 on the left side of the vehicle body 10a, and is arranged so that the output rod 25a faces the outboard side. The steering actuator 5 for the right rear wheel is provided above the beam 33 on the right side of the vehicle body 10a, and is arranged so that the output rod 25a faces the outboard side.

The arm portion 17 of this example is integrally provided on a part of the outer circumference of the outer ring 19 or a part of the outer circumference of the outer ring 16, and projects from the base end toward the front of the vehicle by a predetermined length. The arm portion 17 may be fixed to a part of the outer circumference of the outer ring 19 or a part of the outer circumference of the outer ring 16 by welding, bolts, or the like. The arm portion 17 is rotatably connected to an output rod 25a, which is a linear output portion of the steering actuator 5, via a ball joint Bj. Since the arm portion 17 is arranged so as to project toward the front of the vehicle as described above, holes are formed in the unit support member 3 and the suspension mounting portion 34 to prevent interference with the arm portion 17. Absent.

According to this configuration, since the steering actuator 5 can be installed in the empty space of the vehicle body 10a, it is possible to further reduce the change in the structure on the vehicle side as compared with the above-described embodiment. Other than that, it has the same effect as the above-described embodiment.

As shown in FIGS. 9 and 10, one steering actuator 5 may steer the left and right rear wheels 9R and 9R. The steering actuator 5 is arranged near the middle of the vehicle body (on the spring) 10a in the vehicle width direction so that the actuator body extends in the left-right direction of the vehicle. The left and right output rods 25a and 25a are arranged so as to face the outboard side from one actuator main body.
When the left and right rear wheels 9R and 9R are steered by one steering actuator 5, the number of parts can be reduced and the structure can be simplified as compared with the configuration in which the left and right rear wheels are steered by two steering actuators. However, in this case, the steering angles of the left and right rear wheels 9R and 9R are controlled in the same phase. Other than that, it has the same effect as that of the above-described embodiment.

As shown in FIG. 11, the steering actuator 5 may be fixed to the spring upper Rsa of the rear wheel suspension. The spring upper portion Rsa is fixed to the vehicle body 10a.

<About the steering system>
As shown in FIG. 2, the steering system includes a hub unit 1 with a steering function according to an embodiment and a control device 29 for controlling a steering actuator 5 of the hub unit 1 with a steering function. The control device 29 includes a steering control unit 30 and an actuator drive control unit 31. As shown in FIGS. 2, 8 and 10, the driver operates the steering angle of the front wheels 9F with the steering wheel, but the upper control unit 32 further controls the steering angle of the vehicle 10 according to the operating angle of the steering input unit 11a which is the steering wheel. The steering angle command signals for the left and right rear wheels 9R and 9R calculated in consideration of the situation are output. The steering control unit 30 outputs a current command signal corresponding to the steering angle command signal given by the upper control unit 32.

The upper control unit 32 is a higher control means of the steering control unit 30, and as the upper control unit 32, for example, an electric control unit (Vehicle Control Unit, abbreviated as VCU) that controls the entire vehicle is applied. The ECU connected from the steering actuator 5 via the wiring Wr may be integrated with the VCU or may be provided independently of the VCU.

The actuator drive control unit 31 drives and controls the steering actuator 5 by outputting a current corresponding to the current command signal input from the steering control unit 30. The actuator drive control unit 31 controls the electric power supplied to the coil of the motor 26. The actuator drive control unit 31 constitutes, for example, a half-bridge circuit using a switch element (not shown), and performs PWM control for determining the motor applied voltage according to the ON-OFF duty ratio of the switch element. As a result, the steering angle of the rear wheel 9R can be arbitrarily changed by changing the angle of the hub unit main body 2 with respect to the unit support member 3. Since the steering angle of the rear wheels 9R can be changed according to the traveling conditions of the vehicle 10, it is possible to improve the kinetic performance and fuel efficiency of the vehicle 10.

Instead of operating the steering wheel of the driver, the steering system may operate the steering actuators 5 and 5 by commands of an automatic driving device, a driving support device, etc. (not shown).
Although the embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed this time are exemplary in all respects and are not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 ... Hub unit with steering function, 2 ... Hub unit body, 3 ... Unit support member, 4 ... Rolling bearing, 5 ... Steering actuator, 9R ... Rear wheel, 9a ... Wheel, 10 ... Vehicle, 10a ... Body, 15 ... Hub bearing, 25 ... linear motion mechanism, 25a ... output rod, 26 ... motor, 29 ... control device, 30 ... steering control unit, 31 ... actuator drive control unit, A ... steering axis, Bj ... ball joint, Rs ... Rigid axle suspension (rear wheel suspension), Rsa ... Spring upper part

Claims (7)

A hub unit with a steering function that steers the rear wheels.
A hub unit body having a hub bearing that supports the rear wheels, and
A unit support member provided under the spring of the rear wheel suspension installed on the vehicle body and rotatably supporting the hub unit body around the center of the steering axis extending in the vertical direction.
A steering actuator that rotationally drives the hub unit body around the steering axis, and
With
A hub unit with a steering function in which the steering actuator is arranged above the spring of the vehicle body or the rear wheel suspension. In the hub unit with a steering function according to claim 1, the steering actuator has a motor and a linear motion mechanism that converts the rotational output of the motor into a linear motion of the output rod, and the output rod advances and retreats. As a result, the hub unit with a steering function is driven so that the hub unit main body is rotationally driven around the steering axis center. The hub unit with a steering function according to claim 2, wherein the linear motion mechanism and the hub unit main body are connected via a ball joint. The hub unit with a steering function according to any one of claims 1 to 3, wherein the left and right rear wheels are steered by one of the steering actuators. In the hub unit with a steering function according to any one of claims 1 to 4, the hub unit main body is provided with rolling bearings at two upper and lower positions so as to be rotatable around the steering axis center. A hub unit with a steering function that is supported by the unit support member and whose upper and lower rolling bearings are located in the wheels of the rear wheels. A steering system including the hub unit with a steering function according to any one of claims 1 to 5, and a control device for controlling a steering actuator of the hub unit with a steering function. Is a steering control unit that outputs a current command signal corresponding to a given steering angle command signal, and outputs a current corresponding to the current command signal input from the steering control unit to drive and control the steering actuator. Steering system with actuator drive control unit. A vehicle in which the rear wheels are supported by using the hub unit with a steering function according to any one of claims 1 to 5, and the rear wheel suspension is a torsion beam type suspension.

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