JP6899466B2 - Hub bearing with steering shaft and vehicle equipped with it - Google Patents

Description

The present invention relates to a hub bearing with a steering shaft having a function of steering the left and right rear wheels independently and a vehicle equipped with the hub bearing, and controls the left and right rear wheels to an appropriate steering angle according to a driving situation. By doing so, it relates to a technology for improving fuel efficiency, stabilizing driving performance, and improving safety.

The rear suspension of a vehicle equipped with a general rear wheel steering mechanism adopts an independent suspension system. This steers the rear wheels by pushing and pulling the knuckle in the same way as the manual steering of the front wheels. However, by adopting the independent suspension system, there is a problem that the suspension becomes complicated, the cost increases, and it becomes difficult to secure the indoor space.

Japanese Unexamined Patent Publication No. 2013-39842 Japanese Unexamined Patent Publication No. 2005-178653

Patent Documents 1 and 2 have been proposed as examples of a rear wheel steering mechanism applied to, for example, a torsion beam other than the independent suspension system. In a vehicle equipped with a torsion beam, vehicle body mounting portions extending forward from the left and right ends of the beam extending in the vehicle width direction are attached to the vehicle body, and left and right hub bearings are fastened to the mounting portions extending rearward from the left and right ends of the beam with bolts. Has been done.
In Patent Documents 1 and 2, by applying an external force to the entire torsion beam, the torsion beam and the rubber bush of the vehicle body mounting portion (trailing arm) of the vehicle body are deformed to steer the rear wheels. However, since the left and right wheels cannot be controlled independently and the maximum steering angle is determined by the deformation of the rubber bush, the steering angle is very small and the optimum steering angle cannot be obtained.

In Patent Document 1, the power of the propeller shaft is distributed to give an external force to the torsion beam by a rack and pinion method. This method can only be applied to FR vehicles. In addition, the mechanism is complicated and the size becomes large, and it is not possible to secure a large indoor space.
Patent Document 2 is applied to an electric vehicle. The power of the rear-wheel drive motor is distributed, and the rotational motion is converted into linear motion to give an external force to the torsion beam. In Patent Document 2, as in Patent Document 1, the size is large and a wide indoor space cannot be secured.

An object of the present invention is to provide a hub bearing with a steering shaft capable of optimally controlling the steering angle of the rear wheels independently on the left and right independently while ensuring an interior space, regardless of the suspension system of the rear wheels. To provide a vehicle.

The hub bearing with a steering shaft of the present invention is a hub bearing with a steering shaft for rear wheels that is attached to a rear wheel suspension and rotationally supports the rear wheels.
It has an inner ring, an outer ring, and a double-row rolling element interposed between the inner and outer rings.
The unit support member is rotatably provided around a trunnion shaft-shaped mounting shaft portion provided so as to project vertically from the outer circumference of the outer ring via bearings located in the rear wheel at two locations, upper and lower. It is supported.

The rear wheel suspension may be a rigid axle suspension.
The rigid axle suspension may be a torsion beam axle suspension.

It may have an action point for rotating the hub bearing with a steering shaft around the center of the steering shaft.

In the vehicle of the present invention, the rear wheels are supported by using any of the hub bearings with a steering shaft of the present invention.

An example of a hub unit with a steering function having a hub bearing with a steering shaft of the present invention will be described. This hub unit with a steering function 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,
A unit support member provided on the rear wheel suspension that rotatably supports the hub unit body around the steering axis extending in the vertical direction.
A steering actuator for rotationally driving the hub unit main body around the center of the steering shaft was provided.

Independent suspension type suspension has a kingpin shaft, so the rear wheels can be steered independently on the left and right by providing a steering actuator that can push and pull around the kingpin shaft. However, in the torsion beam, since the left and right hub bearings are fastened to the left and right ends of the beam by bolts, the left and right rear wheels cannot be steered independently.
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. In addition, since the rear wheel suspension is provided with a unit support member that rotatably supports the hub unit body, the structure can be simplified and the structure can be simplified as compared with the conventional technology for distributing the power of the propeller shaft or the motor for driving the rear wheels. A large indoor space can be secured.
Further, according to this configuration, the function of steering the rear wheels enables steering at a slight angle independently for each rear wheel. Since the steering angle around the steering axis of the hub unit body can be freely changed within a certain range by the steering actuator, for example, the steering angle of the rear wheels can be arbitrarily corrected according to the traveling condition of the vehicle. can do. For example, if the steering angle of the rear wheels is set to the same phase as that of the front wheels, yaw generated in the vehicle during steering can be suppressed and the stability of the vehicle can be improved. Furthermore, the running stability of the vehicle can be ensured by adjusting the steering angle of the rear wheels independently on the left and right even when traveling in a straight line.

The steering actuator may include a motor, a speed reducer that reduces the rotation of the motor, and a linear motion mechanism that converts the rotational output of the speed reducer into linear motion. In this case, by interposing a speed reducer between the motor and the linear motion mechanism, it is possible to reduce the size of the motor while increasing the torque of the steering actuator.

The linear motion mechanism may be a feed screw mechanism using a trapezoidal thread.
In the above-mentioned conventional technique, since a lock mechanism or the like for maintaining the steering angle is not provided for the reverse input from the tire, constant power is required to maintain the steering angle.
On the other hand, according to the configuration in which the linear motion mechanism is a feed screw mechanism using a trapezoidal thread, the effect of preventing reverse input from the tire can be enhanced. Therefore, it is not necessary to constantly apply a driving force to the steering actuator in order to maintain the steering angle, so that it is possible to improve electricity cost or fuel consumption.

The hub unit main body is supported by the unit support member via rolling bearings at two points above and below so as to be rotatable around the center of the steering axis extending in the vertical direction, and the upper and lower rolling bearings are the wheels of the rear wheels. It may be located inside. 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.

This steering system 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, and the control device is provided. A steering control unit that outputs a current command signal corresponding to the steering angle command signal, and an actuator drive control that outputs a current corresponding to the current command signal input from the steering control unit to drive and control the steering actuator. Has a part.

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.

This vehicle 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 rigid axle suspension. In this case, the hub unit with steering function can be installed on the existing rigid axle suspension without major structural changes. Even if the rear wheel suspension is a rigid axle suspension, the hub unit with steering function can be easily installed.

The hub bearing with a steering shaft of the present invention is a hub bearing with a steering shaft attached to a rear wheel suspension to rotationally support the rear wheels, and is interposed between the inner ring, the outer ring, and the inner and outer rings. It has a multi-row rolling element, and is provided on the unit support member in a tranny shaft shape that protrudes vertically from the outer circumference of the outer ring via bearings located in the wheels of the rear wheels at two places above and below. Since it is supported so as to be rotatable around the shaft, the steering angle of the rear wheels can be optimally controlled separately on the left and right independently while ensuring the interior space, regardless of the suspension system of the rear wheels.

In the vehicle of the present invention, since the rear wheels are supported by the hub bearing with the steering shaft of the present invention, the steering angle of the rear wheels is left and right while ensuring the interior space regardless of the suspension system of the rear wheels. It can be independently and individually optimally controlled.

This hub unit with a steering function is a hub unit with a steering function that steers the rear wheels, and is provided on a hub unit main body having a hub bearing for supporting the rear wheels and a rear wheel suspension, and moves the hub unit main body up and down. A unit support member that rotatably supports around the steering shaft center extending in the direction and a steering actuator that rotationally drives the hub unit main body around the steering shaft center are provided. Therefore, regardless of the suspension system of the rear wheels, the steering angles of the rear wheels can be optimally controlled separately on the left and right independently while securing the interior space.

This steering system 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, and the control device is provided. A steering control unit that outputs a current command signal corresponding to the steering angle command signal, and an actuator drive control that outputs a current corresponding to the current command signal input from the steering control unit to drive and control the steering actuator. Has a part. Therefore, regardless of the suspension system of the rear wheels, the steering angles of the rear wheels can be optimally controlled separately on the left and right independently while securing the interior space.

This vehicle is a vehicle in which the rear wheels are supported by using the hub unit with a steering function described in any of the above, and since the rear wheel suspension is a rigid axle suspension, the rear wheel suspension system is used. Instead, the steering angle of the rear wheels can be optimally controlled separately on the left and right independently while ensuring the interior space.

It is a vertical cross-sectional view which shows the structure of the hub unit with a steering function which concerns on 1st Embodiment of this invention, and the periphery thereof. It is a horizontal cross-sectional view which shows the structure of the hub unit with a steering function and its periphery. It is a perspective view which shows the appearance of the hub unit with a steering function. It is a side view of the hub unit with a steering function. It is a top view of the hub unit with the steering function. FIG. 6 is a sectional view taken along line VI-VI of FIG. It is a top view which shows the example which the hub unit with the steering function is mounted on the torsion beam. It is a perspective view which shows the example which the hub unit with the steering function is mounted on the torsion beam. It is a schematic plan view of the vehicle provided with the hub unit with the steering function.

[First Embodiment]
A hub unit with a steering function including a hub bearing with a steering shaft according to an embodiment of the present invention will be described with reference to FIGS. 1 to 9.
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 FIG. 1, 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. The unit support member 3 is provided on the rear wheel suspension, which will be described later. A vehicle equipped with this hub unit 1 with a steering function steers the left and right front wheels 9F and 9F (FIG. 9) by operating the steering wheel, and at the same time, makes the left and right rear wheels 9R and 9R (FIG. 9) at a minute angle (about ± 5 deg). ) It can be steered independently.

The actuator body 7 of the steering actuator 5 is provided on the inboard side of the unit support member 3, and the hub unit 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. 9), the outside of the vehicle 10 (FIG. 9) in the vehicle width direction is referred to as the outboard side, and the center side of the vehicle 10 (FIG. 9) in the vehicle width direction is referred to as the outboard side. It is called the inboard side.

As shown in FIGS. 2 and 3, the hub unit main body 2 and the actuator main body 7 are connected by a joint portion 8. Normally, boots (not shown) are attached to the joint portion 8 for waterproof and dustproof purposes.
As shown in FIG. 1, the hub unit main body 2 is supported by the unit support member 3 via rolling bearings 4 and 4 at two positions in the vertical direction so as to be rotatable around the steering axis A extending in the vertical direction. There is. 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 hub unit 1 with steering function>
As shown in FIGS. 7 to 9, the hub unit 1 with a steering function is fixed to the rigid axle suspension Rs, which is the rear wheel suspension in the vehicle 10. In this example, the torsion beam axle type suspension of the rigid axle suspension Rs is applied. The unit support members 3 (FIG. 3) of the hub unit 1 with a steering function are fixed to the mounting portions 34 and 34 provided at both left and right ends of the beam 33 in the torsion beam axle type suspension, respectively. Although not shown, the hub unit 1 with a steering function may be fixed to another suspension mechanism such as a multi-link suspension mechanism as a rear wheel suspension type.

<About hub unit body 2>
As shown in FIGS. 1 and 6, 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 (FIG. 3) that is a steering force receiving portion described later. .. 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. A hub bearing 15 with upper and lower mounting shafts 16b, which is a steering shaft, constitutes a hub bearing with a steering shaft, which is a hub bearing with a steering shaft.
As shown in FIG. 2, the brake 21 has a brake rotor 21a and a brake caliper 21b. The brake caliper 21b is attached to the upper and lower brake caliper mounting portions 22 (FIG. 4) formed by integrally projecting from the outer ring 19 in an arm shape.

<Rotation allowable support parts and unit support members>
As shown in FIG. 6, a tapered roller bearing is applied as the rolling bearing 4 which is each rotation allowable support component. In this example, a tapered roller bearing is applied as the rolling bearing 4. The rolling bearing 4 has an inner ring 4a fitted to the outer periphery of the mounting shaft portion 16b, an outer ring 4b fitted to the unit support member 3, and a plurality of rolling elements 4c interposed between the inner and outer rings 4a and 4b. .. As shown in FIG. 1, the upper and lower rolling bearings 4 and 4 are provided so as to be located in the wheel 9b.

The unit support member 3 has a unit support member main body 3A and a unit support member coupling body 3B. As shown in FIG. 6, a substantially ring-shaped unit support member coupling body 3B is detachably fixed to the outboard side end of the unit support member main body 3A. Partial concave spherical fitting hole forming portions are formed on the upper and lower portions of the inboard side side surface of the unit support member coupling 3B.

As shown in FIGS. 5 and 6, partial concave spherical fitting hole forming portions are formed at the upper and lower portions of the outboard side ends of the unit support member main body 3A. The unit support member coupling body 3B is fixed to the outboard side end of the unit support member main body 3A, and the fitting hole forming portions are combined with each other at the upper and lower portions to form a fitting hole continuous to the entire circumference. .. The outer ring 4b is fitted in this fitting hole.

As shown in FIG. 6, 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 surface of the inner ring 4a, and a pressing force is applied to the end surface of the inner ring 4a by a bolt 23 screwed into the female thread 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 this hub unit, the initial preload is set so that it does not 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 FIG. 2, 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 projects integrally with a part of the outer circumference of the outer ring 19. The arm portion 17 is rotatably connected to the linear motion output portion 25a of the steering actuator 5 via the joint portion 8. As a result, the linear output unit 25a of the steering actuator 5 moves forward and backward, so that the hub unit main body 2 is rotated around the steering axis A (FIG. 1), that is, steered.

<Steering actuator 5>
As shown in FIG. 3, the steering actuator 5 has an actuator body 7 that rotationally drives the hub unit body 2 around the steering axis A (FIG. 1).
As shown in FIG. 2, the actuator main body 7 converts the motor 26, the speed reducer 27 for decelerating the rotation of the motor 26, and the forward and reverse rotation outputs of the speed reducer 27 into a reciprocating linear operation of the linear output unit 25a. A linear motion mechanism 25 is provided. The motor 26 is, for example, a permanent magnet type synchronous motor, but may be a DC motor or an induction motor.

As the speed reducer 27, a winding type transmission mechanism such as a belt transmission mechanism or a gear train or the like can be used, and the belt transmission mechanism is used in the example of FIG. The speed reducer 27 has a drive pulley 27a, a driven pulley 27b, and a belt 27c. A drive pulley 27a is coupled to the motor shaft of the motor 26, and a driven pulley 27b is provided in the linear motion mechanism 25. The driven pulley 27b is arranged parallel to the motor shaft. The driving force of the motor 26 is transmitted from the drive pulley 27a to the driven pulley 27b via the belt 27c. The drive pulley 27a, the driven pulley 27b, and the belt 27c constitute a winding type speed reducer 27.

As the linear motion mechanism 25, a feed screw mechanism such as a slide screw or a ball screw, a rack pinion mechanism, or the like can be used. In this example, a feed screw mechanism 25b using a trapezoidal thread slide screw is used. Since the linear motion mechanism 25 is a feed screw mechanism using the trapezoidal thread sliding screw, the effect of preventing reverse input from the tire 9b can be enhanced. The actuator main body 7 including the motor 26, the speed reducer 27, and the linear motion mechanism 25 is assembled as a semi-assembly and is detachably attached to the case 6b with bolts or the like. A mechanism that directly transmits the driving force of the motor 26 to the linear motion mechanism 25 without going through a speed reducer is also possible.

The case 6b is integrally formed with the unit support member main body 3A as a part of the unit support member 3. The case 6b is formed in a bottomed tubular shape, and is provided with a motor accommodating portion for supporting the motor 26 and a linear motion mechanism accommodating portion for supporting the linear motion mechanism 25. The motor accommodating portion is formed with a fitting hole that supports the motor 26 at a predetermined position in the case. The linear motion mechanism accommodating portion is formed with a fitting hole that supports the linear motion mechanism 25 at a predetermined position in the case, a through hole that allows the linear motion output unit 25a to move forward and backward, and the like.

<Effect>
According to the hub unit 1 with a steering function described above, the hub unit main body 2 having a hub bearing supporting the rear wheel 9R can be freely rotated around the steering axis A by driving the steering actuator 5. it can. Further, since the unit support member 3 that rotatably supports the hub unit body 2 is provided on the rear wheel suspension, the structure can be simplified as compared with the conventional technique of distributing the power of the propeller shaft or the motor for driving the rear wheels. A wide interior space of the vehicle 10 can be secured.

Further, according to this configuration, the function of steering the rear wheels 9R enables steering at a slight angle independently for each rear wheel 9R. The steering actuator 5 can freely change the steering angle around the steering axis A of the hub unit main body 2 within a certain range. Therefore, for example, the rear wheel 9R is steered according to the traveling condition of the vehicle 10. The angle can be corrected arbitrarily. 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, the running stability of the vehicle 10 can be ensured by adjusting the steering angles of the rear wheels 3R independently on the left and right even when traveling in a straight line. In addition, it is possible to improve fuel efficiency by setting an appropriate tire angle according to the driving conditions at that time.

<About the steering system>
As shown in FIG. 3, 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. The driver operates the steering angle of the front wheels with the steering wheel, but in the upper control unit 32, the situation of the vehicle 10 (FIG. 9) is further taken into consideration according to the operation angle of the steering input unit 11a (FIG. 9) which is the steering wheel. The calculated steering angle command signals for the left and right rear wheels 9R and 9R (FIG. 9) 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 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 wheels 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 can be changed according to the traveling conditions of the vehicle, it is possible to improve the kinetic performance of the vehicle and to drive stably and safely.

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, 15 ... Hub bearing, 25 ... Linear mechanism, 25b ... Feed screw mechanism, 26 ... Motor, 27 ... Reducer, 29 ... Control device, 30 ... Steering control unit, 31 ... Actuator drive control unit, Rs ... Rigid axle suspension (rear wheel suspension)

Claims (5)

A hub bearing with a steering shaft for rear wheels that is attached to the rear wheel suspension and supports the rotation of the rear wheels.
It has an inner ring, an outer ring, and a double-row rolling element interposed between the inner and outer rings.
The unit support member is rotatably provided around a tranion shaft-shaped mounting shaft portion provided so as to project vertically from the outer periphery of the outer ring via bearings located in the rear wheel at two locations, upper and lower. and supported by, bearings, rolling steering axle with a hub bearing that is installed fitted to the outer periphery of the mounting shaft portion located within the wheel. The hub bearing with a steering shaft according to claim 1, wherein the rear wheel suspension is a rigid axle suspension. The hub bearing with a steering shaft according to claim 2, wherein the rigid axle suspension is a torsion beam axle type suspension. In the hub bearing with a steering shaft according to any one of claims 1 to 3, the hub bearing with a steering shaft has a steering shaft having an action point for rotating the hub bearing with the steering shaft around the center of the steering shaft. Hub bearing. A hub bearing with a steering shaft in which the rear wheels are supported by using the hub bearing with a steering shaft according to any one of claims 1 to 4.

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