JP7049864B2 - Vehicles with a steering hub unit, steering system, and steering hub unit - Google Patents

Description

The present invention is a hub unit with a steering function, a steering system, and a hub unit with a steering function, which have a function of performing auxiliary steering such as steering added to steering by a steering device or rear wheel steering. Regarding the vehicle equipped with, the technology for improving fuel efficiency, stabilizing the running performance of the vehicle, and improving the safety.

In a vehicle such as a general automobile, the steering wheel and the steering device are mechanically connected, and both ends of the steering device are connected to the left and right wheels by tie rods. Therefore, the turning angle of the left and right wheels due to the movement of the steering wheel is determined by the initial setting.
The geometry of the vehicle is (1) "parallel geometry" where the left and right wheels have the same turning angle, and (2) the turning inner wheel wheel angle is cut larger than the turning outer wheel angle in order to have one turning center. "Ackerman geometry" is known.

The geometry of the vehicle affects the stability and safety of driving.
For example, Patent Documents 1 and 2 have been proposed with respect to a mechanism in which the steering geometry is made variable according to a traveling situation. In Patent Document 1, the steering geometry is changed by changing the position of the knuckle arm and the joint relative to each other. In Patent Document 2, two motors are used to enable both the toe angle and the camber angle to be tilted to an arbitrary angle. Further, a mechanism for independent steering of four wheels is proposed in Patent Document 3.

Japanese Unexamined Patent Publication No. 2009-226972 German Patent Application Publication No. 1020122036337 Japanese Unexamined Patent Publication No. 2014-061744

Ackermann geometry has a difference in steering angle between the left and right wheels so that each wheel turns around a common point in order to make the wheels turn smoothly when turning at low speeds where the centrifugal force acting on the vehicle can be ignored. Is set. However, in a high-speed turning where the centrifugal force cannot be ignored, it is desirable that the wheels generate a cornering force in a direction in which the centrifugal force is balanced, so it is preferable to use a parallel geometry rather than an Ackermann geometry.

As mentioned above, a typical vehicle steering device is mechanically connected to the wheels, so it can generally only take a single fixed steering geometry, somewhere between Ackermann geometry and parallel geometry. Often set to a typical geometry. However, in this case, the difference in steering angle between the left and right wheels is insufficient in the low speed range, and the steering angle of the outer ring becomes excessive, and in the high speed range, the steering angle of the inner wheel becomes excessive. If there is an unnecessary bias in the wheel lateral force distribution of the inner and outer wheels in this way, it causes deterioration of fuel efficiency due to deterioration of running resistance and premature wear of the wheels, and the inner and outer wheels cannot be used efficiently, resulting in smooth cornering. There is a problem that the wheel is damaged.

According to the proposals of Patent Documents 1 and 2, the steering geometry can be changed, but there are the following problems.
In Patent Document 1, as described above, the steering geometry is changed by relatively changing the knuckle arm and the joint position, but a motor actuator that obtains a large force enough to change the geometry of the vehicle in such a portion is used. It is very difficult to prepare due to space constraints. Further, the change in the wheel angle due to the change at this position is small, and in order to obtain a large effect, it is necessary to make a large change, that is, to move a large amount.

In Patent Document 2, since two motors are used, the cost increases due to the increase in the number of motors, and the control becomes complicated.
Patent Document 3 can be applied only to a vehicle with four-wheel independent steering, and since the hub bearing is cantilevered and supported for the steering shaft, the rigidity is lowered and the steering geometry is changed due to the occurrence of excessive running G. It may change.
Further, when a speed reducer is provided on the steering shaft, a large amount of power is required. For this reason, the motor is made large, but if the motor is made large, it becomes difficult to arrange the whole on the inner peripheral portion of the wheel.
Further, when a speed reducer having a large reduction ratio is provided, the responsiveness deteriorates.

As described above, the conventional mechanism provided with the auxiliary steering function has a complicated configuration because it is intended to arbitrarily change the toe angle or camber angle of the wheels in the vehicle. In addition, it becomes difficult to secure the rigidity, and in order to secure the rigidity, it is necessary to increase the size and increase the weight.

In a vehicle, in order to arbitrarily change the toe angle or camber angle of the wheels, a complicated configuration is required and a large number of components are required.
In order to improve the maneuverability and stability of the vehicle, it is necessary to accurately steer the steering angles of the left and right wheels. Even if the sensor is provided in the steering actuator, there are individual differences due to the rigidity of the actuator, and it is difficult to obtain an accurate steering angle within a minute angle (about ± 5 deg). Examples of the rigidity include backlash of gears and the like, backlash of a linear motion mechanism, case rigidity of an actuator, and the like.
Further, when the steering angle is controlled by only one sensor, if the sensor becomes abnormal, the running performance of the vehicle may be hindered.

An object of the present invention is to provide a vehicle provided with a steering function hub unit, a steering system, and a steering function hub unit capable of improving the maneuverability and stability of the vehicle.

The hub unit with a steering function of the present invention is provided on a hub unit body having a hub bearing for supporting wheels and a suspension frame component of a suspension device, and is provided around the steering axis center extending the hub unit body in the vertical direction. A unit support member that rotatably supports the hub unit body and a rolling actuator that rotationally drives the hub unit body around the steering axis center are provided.
The hub unit body is provided with a steering angle detecting means for detecting the rotation angle around the steering axis center.

According to this configuration, the hub unit main body including the hub bearing that supports the wheels can be freely rotated around the steering axis center by driving the steering actuator. Therefore, the steering can be independently performed for each wheel, and the toe angle of the wheels can be arbitrarily changed according to the traveling condition of the vehicle.
Therefore, it may be used for either a steering wheel such as a front wheel or a non-steering wheel such as a rear wheel. When used for a steering wheel, by installing it on a member whose direction can be changed by the steering device, it is added to the steering by the driver's steering wheel operation, and the left and right wheels are individually or the left and right wheels are interlocked with each other. It is a mechanism to change the steering angle.

Further, when turning, the difference in steering angle between the left and right wheels can be changed according to the traveling speed. For example, the steering geometry can be changed during running, for example, the parallel geometry is used for turning in the high speed range, and the Ackermann geometry is used for turning in the low speed range. Since the steering angle of the wheels can be arbitrarily changed during traveling in this way, it is possible to improve the kinetic performance of the vehicle and to drive stably and safely. Furthermore, by appropriately changing the steering angles of the left and right steering wheels, it is possible to reduce the turning radius of the vehicle during turning and improve the turning performance. Furthermore, even during straight-line driving, by adjusting the amount of toe angle according to each situation, it is possible to make adjustments such as ensuring driving stability without deteriorating fuel efficiency.

In order to control the behavior of the vehicle by changing the wheel steering angle in this way, it is necessary to accurately control the wheel steering angle.
According to this configuration, in particular, since the hub unit body is provided with a steering angle detecting means for detecting the rotation angle around the steering axis center, for example, a sensor provided in the steering actuator for detecting the steering angle. Even if an abnormality occurs, it is possible to accurately control the angle of the wheels to a desired angle by using the steering angle detecting means. Even if there are individual differences due to the rigidity of the steering actuator, for example, by setting the relationship between the output signals of a plurality of steering angle detecting means in advance by a test or the like, a minute steering angle range can be set. It is possible to take an accurate steering angle within. Therefore, the maneuverability and stability of the vehicle can be improved.

The steering angle detecting means is an angle sensor that directly detects the steering angle, and this angle sensor may be provided on the steering axis. When the angle sensor is provided on the steering shaft in this way, it is possible to accurately output a minute angle change of the hub bearing. This makes it possible to accurately control the angle of the wheel according to a desired angle.

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

According to this configuration, the control unit outputs a current command signal corresponding to a given steering angle command signal. The actuator drive control unit outputs a current corresponding to the current command signal input from the control unit to drive and control the rolling actuator. Therefore, the steering angle of the wheel can be arbitrarily changed in addition to the steering by the driver's steering wheel operation.

The steering actuator includes a motor and a linear motion mechanism that converts the rotational output of the motor into a reciprocating linear operation, and the steering angle detecting means includes an angle sensor that directly detects the steering angle and the motor. A rotation sensor that indirectly detects the steering angle according to the conditions determined from the rotation angle of the above, and a position sensor that indirectly detects the steering angle according to the conditions determined from the position of the linear motion output unit in the linear motion mechanism. And, with
Even if the control unit compares the output signals of at least two of the angle sensor, the rotation sensor, and the position sensor with each other and determines an abnormality of the steering angle detecting means according to a determined criterion. good.
The above-mentioned defined conditions and the above-mentioned determined judgment criteria are conditions and judgment criteria arbitrarily determined by design and the like, and for example, conditions and judgment criteria appropriate for one or both of test and simulation. It is sought and determined.

According to this configuration, the control unit converts the output signals of a plurality of sensors into the steering angles of the wheels, and when all of them match, the control unit determines that the steering angle detecting means is in a normal state and maintains control. Can be done. When the steering angles of the wheels do not match, the control unit may determine that any steering angle detecting means is in an abnormal state.

The vehicle of the present invention is supported by one or both of the front wheels and the rear wheels by using a hub unit with a steering function having any of the above configurations of the present invention.
Therefore, the above-mentioned effects can be obtained for the hub unit with the steering function of the present invention. The front wheels are generally regarded as steering wheels, but when the hub unit with a steering function of the present invention is applied to the steering wheels, it is effective for adjusting the toe angle during traveling. Further, the rear wheels are generally regarded as non-steering wheels, but when applied to non-steering wheels, the minimum turning radius at low speed can be reduced by slightly steering the non-steering wheels.

The hub unit with a steering function of the present invention is provided on a hub unit body having a hub bearing for supporting wheels and a suspension frame component of a suspension device, and is provided around the steering axis center extending the hub unit body in the vertical direction. A unit support member that rotatably supports the hub unit body and a rolling actuator that rotationally drives the hub unit body around the steering axis center are provided, and the rotation angle of the hub unit body around the steering axis center is detected. It was equipped with a steering angle detecting means. Therefore, the maneuverability and stability of the vehicle can be improved.

It is a vertical 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 sectional view which shows the structure of the hub unit with a steering function and its surroundings. It is a perspective view which shows the appearance of the hub unit with the same steering function. It is a side view of the hub unit with the same steering function. (A) is a plan view of the hub unit with a steering function, and (B) is a partially enlarged view of a part of FIG. 5 (A). FIG. 4 is a sectional view taken along line VI-VI of FIG. It is a horizontal sectional view of the linear motion mechanism of the hub unit with the same steering function. It is a block diagram of the control device which controls the steering actuator of the hub unit with a steering function. It is a schematic plan view of an example of a vehicle to which a hub unit with a steering function of an embodiment is applied.

<First Embodiment>
The hub unit with a steering function according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 8.
<Rough 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 rotation allowable support component 4, a steering actuator 5, and a plurality of steering angles described later. It is provided with a detection means. The unit support member 3 is integrally provided with the knuckle 6 which is a suspension frame component. The actuator main body 7 of the steering actuator 5 is provided on the inboard side of the unit support member 3, and 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, the outside of the vehicle in the vehicle width direction is referred to as the outboard side, and the center side of the vehicle in the vehicle width direction is referred to as 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 rotation allowable support parts 4 and 4 at two upper and lower positions so as to be rotatable around the steering axis A extending in the vertical direction. Has been done. The steering axis A is different from the rotation axis O of the wheel 9, and is also different from the kingpin axis that mainly performs steering. In a normal vehicle, the kingpin angle is set to 10 to 20 degrees for the purpose of improving the straight running stability of the vehicle, but the hub unit 1 with the auxiliary steering function of this embodiment is different from the kingpin angle. It has a steering axis with an angle (axis) of. The wheel 9 includes a wheel 9a and a tire 9b.

<Installation location of hub unit 1 with steering function>
In this embodiment, the hub unit 1 with a steering function is added to the steering wheels of the steering wheel, specifically, as shown in FIG. 9, by the steering device 11 of the front wheels _9F of the vehicle 10, and the left and right wheels are individually minute. As a mechanism for steering at various angles (about ± 5 deg), it is integrally provided on the knuckle 6 which is a suspension frame component of the suspension device 12.

As shown in FIG. 2, the steering device 11 is a device that steers the wheels 9 in response to the operation of the steering wheel (not shown). FIG. 2 is a view of the suspension from above. A steering device 11 for a normal vehicle is connected to the steering coupling portion 6d (described later) of the hub unit 1 with a steering function via a tie rod 14, and the wheels 9 are steered by the steering wheel operation of the driver. It is possible. In addition to this, the hub unit 1 with a steering function may be used as a mechanism for steering the rear wheels _9R (FIG. 9) as an aid to steering the front wheels. As the suspension device 12 (FIG. 9), any one of a strut type suspension mechanism, a multi-link type suspension mechanism, and another suspension mechanism is applied.

<About the hub unit body 2>
As shown in FIG. 1, the hub unit main body 2 includes a hub bearing 15 for supporting the wheels 9, an outer ring 16, and an auxiliary steering force receiving portion 17 (FIG. 3) described later.
As shown in FIG. 6, 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, 19 and has a member on the vehicle body side and a wheel 9 (FIG. 6). It serves to connect with 1).

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. As shown in FIG. 1, the wheel 9a of the wheel 9 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.

As shown in FIG. 6, the outer ring 16 has an annular portion 16a fitted to the outer peripheral surface of the outer ring 19 and a trunnion shaft-shaped mounting shaft portion provided so as to project vertically from the outer periphery of the annular portion 16a. It has 16b and 16b. Each mounting shaft portion 16b is provided coaxially with the steering shaft center A.
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 projecting integrally with the outer ring 19 in an arm shape.

<Rotation allowable support parts and unit support members>
As shown in FIG. 6, each rotation allowable support component 4 is composed of rolling bearings. In this example, tapered roller bearings are applied as rolling bearings. The rolling bearing includes 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 as described later, and a plurality of rolling elements 4c interposed between the inner and outer rings 4a and 4b. And have.

The unit support member 3 has a unit support member main body 3A and a unit support member coupling 3B. A substantially ring-shaped unit support member coupling 3B is detachably fixed to the outboard side end of the unit support member main body 3A. Partially concave spherical fitting hole forming portions 3a 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. 5A and 6, partial concave spherical fitting hole forming portions 3Aa are formed at the upper and lower portions of the outboard side ends of the unit support member main body 3A. .. As shown in FIG. 3, the unit support member coupling 3B is fixed to the outboard side end of the unit support member main body 3A, and the fitting hole forming portions 3a and 3Aa (FIG. 5A) are provided at the upper and lower portions thereof. By combining with each other, a fitting hole extending all around is formed. In FIG. 3, the unit support member 3 is represented by a alternate long and short dash line. As shown in FIG. 6, the outer ring 4b is fitted into the fitting hole.

Each mounting shaft portion 16b is formed so that the female threaded portion extends in the radial direction, and a bolt 23 screwed to the female threaded 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 apply a preload to each rotation allowable support component 4. Giving. As a result, the rigidity of each rotation allowable support component 4 can be increased. As the rolling bearing of the rotation allowable support component 4, an angular contact ball bearing or a four-point contact ball bearing may be used instead of the tapered roller bearing. In that case as well, preload can be applied in the same manner as described above.

As shown in FIG. 2, the auxiliary steering force receiving portion 17 is a portion serving as an action point for applying an auxiliary steering force to the outer ring 19 of the hub bearing 15, and an arm projecting integrally with a part of the outer periphery of the outer ring 19. It is provided as a part. The auxiliary steering force receiving 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 rotates around the steering axis A (FIG. 1), that is, auxiliary steering is performed.

<Actuator for steering 5>
As shown in FIG. 3, the steering actuator 5 has an actuator main body 7 that rotationally drives the hub unit main 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 / reverse rotation output of the speed reducer 27 into a reciprocating linear operation of the linear motion 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 in the example of FIG. 2, the belt transmission mechanism is used. 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 and pinion mechanism, or the like can be used, and in this example, a feed screw mechanism using a trapezoidal thread slide screw is used. Since the linear motion mechanism 25 includes 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. The actuator main body 7 including the motor 26, the speed reducer 27, and the linear motion mechanism 25 is assembled as a semi-assembled product and is detachably attached to the case 6b by 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 the 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 cylindrical shape, and is provided with a motor accommodating portion that supports the motor 26 and a linear motion mechanism accommodating portion that supports 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 portion 25a to move forward and backward, and the like.

As shown in FIG. 3, the unit support member main body 3A includes the case 6b, the shock absorber mounting portion 6c which is the mounting portion of the shock absorber, and the steering device connecting portion 6d which is the connecting portion of the steering device 11 (FIG. 2). Have. The shock absorber mounting portion 6c and the steering device coupling portion 6d are also integrally formed with the unit support member main body 3A. The shock absorber mounting portion 6c is formed so as to protrude from the upper portion of the outer surface portion of the unit support member main body 3A. A steering device coupling portion 6d is formed so as to project from a side surface portion of the outer surface portion of the unit support member main body 3A.

<Rudder angle detection means>
As shown in FIGS. 5 to 7, the plurality of (three in this example) steering angle detecting means S detect the rotation angle around the steering axis A of the hub unit main body 2. As shown in FIGS. 5A and 5B, one of the plurality of steering angle detecting means S is an angle sensor Sa that directly detects the steering angle, and is provided on the steering axis. The angle sensor Sa has an encoder Saa provided on the upper surface of the pressing member 24 on the rotating side and a magnetic sensor portion Sab provided on the unit support member 3 on the fixed side and facing the encoder Saa with a gap.

As shown in FIG. 5B, the encoder Saa of this example is a magnetic encoder having a magnetic track in which N poles and S poles are alternately magnetized along the circumferential direction. The encoder Saa may be formed on the pressing member 24 itself. Although not shown, the encoder Saa may be a pulsar ring made of a magnetic metal material having a gear shape in which concave portions and convex portions are alternately arranged in the circumferential direction. The output signal of the magnetic sensor unit Sab is given to the target left and right wheel tire angle calculation unit 159 (FIG. 8), which will be described later. In the target left and right wheel tire angle calculation unit 159 (FIG. 8), for example, the output signal is pulsed and the steering angle is calculated based on the number of pulses.

As shown in FIGS. 6 and 7, the plurality of steering angle detecting means S have a rotation sensor Sb and a position sensor Sc that indirectly detect the steering angle. As shown in FIG. 6, the rotation sensor Sb detects and outputs a signal indicating a relative rotation angle between the stator and the rotor of the motor 26. The rotation sensor Sb is arranged close to the detected portion Sba provided on the outer peripheral surface of the rotary output shaft 26a of the rotor and the detected portion Sba provided in the motor accommodating portion in the case 6b, for example, facing each other in the radial direction. It has a detection unit Sbb. The output signal of the rotation sensor Sb is given to the target left and right wheel tire angle calculation unit 159 (FIG. 8). For example, a resolver or the like is applied as such a rotation sensor Sb. The rotation sensor Sb is used for detecting the steering angle and controlling the rotation of the motor 26.

As shown in FIG. 7, the position sensor Sc indirectly detects the steering angle according to the conditions determined from the position of the linear motion output unit 25a in the linear motion mechanism 25. For example, a magnetic sensor is applied to this position sensor Sc. The position sensor Sc has a magnetic target and a magnetic sensor unit Sca. The magnetic target comprises a permanent magnet provided in a linear motion output unit 25a that moves linearly. The magnetic sensor unit Sca is provided in the linear motion mechanism accommodating portion in the case 6b. The magnetic sensor unit Sca is arranged so as to face the magnetic target at a predetermined position in the radial direction. As the magnetic sensor unit Sca, for example, a Hall IC or the like is applied. The magnetic sensor unit Sca reads the magnetic force of the magnetic target and detects the axial position of the linear motion output unit 25a. The output signal of the magnetic sensor unit Sca is given to the target left and right wheel tire angle calculation unit 159 (FIG. 8).

<About the steering system>
As shown in FIG. 3, this steering system includes the hub unit 1 with a steering function and a control device 29 for controlling the steering actuator 5 of the hub unit 1 with a steering function. The control device 29 has a control unit 30 and an actuator drive control unit 31. The control unit 30
The output of at least one of the angle sensor Sa, the rotation sensor Sb (FIG. 8) and the position sensor Sc (FIG. 8), and the auxiliary steering angle command signal (turning angle command signal) given from the upper control unit 32. Outputs a current command signal according to.

The upper control unit 32 is a higher control means of the 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 outputs a current corresponding to the current command signal input from the control unit 30 to drive and control the steering actuator 5. The actuator drive control unit 31 constitutes, for example, a half-bridge circuit using a switching element (not shown), and performs PWM control for determining the motor applied voltage according to the ON-OFF duty ratio of the switching element. As a result, the wheel can be slightly changed in angle in addition to the steering by the driver's steering wheel operation. Even when traveling in a straight line, the amount of toe angle can be adjusted according to each situation.

<Detailed configuration of control unit 30>
As shown in FIG. 8, the control unit 30 includes a normative lateral acceleration calculation unit 152, a right wheel tire angle calculation unit 153, a left wheel tire angle calculation unit 154, a right wheel road surface friction coefficient calculation unit 155, a target yaw rate calculation unit 156, and a left wheel. It includes a road surface friction coefficient calculation unit 157, a target yaw rate correction unit 158, a target left and right wheel tire angle calculation unit 159, a right wheel command value calculation unit 160, and a left wheel command value calculation unit 161.

The right wheel tire angle calculation unit 153 and the left wheel tire angle calculation unit 154 acquire steering angle information and vehicle height information from the upper control unit 32 in a predetermined cycle. The right wheel tire angle calculation unit 153 and the left wheel tire angle calculation unit 154 calculate the current angle of the tire (wheel) to be steered by this steering system based on the acquired steering angle information and vehicle height information. The right wheel tire angle calculation unit 153 and the left wheel tire angle calculation unit 154 output the calculated tire angle information to the normative lateral acceleration calculation unit 152.

The normative lateral acceleration calculation unit 152 calculates the normative lateral acceleration based on the vehicle speed information acquired from the upper control unit 32 and the tire angle information. That is, the standard lateral acceleration calculation unit 152 determines the standard lateral acceleration based on the tire angle represented by the tire angle information and the vehicle speed represented by the vehicle speed information from the right wheel tire angle calculation unit 153 and the left wheel tire angle calculation unit 154. Make a calculation. The standard lateral acceleration calculation unit 152 outputs the calculated standard lateral acceleration as the standard lateral acceleration information to the right wheel road surface friction coefficient calculation unit 155 and the left wheel road surface friction coefficient calculation unit 157.

The right wheel surface friction coefficient calculation unit 155 and the left wheel road surface friction coefficient calculation unit 157 are based on the actual lateral acceleration information acquired from the upper control unit 32 and the reference lateral acceleration information input from the reference lateral acceleration calculation unit 152. Calculate the coefficient. Specifically, the right wheel road surface friction coefficient calculation unit 155 and the left wheel road surface friction coefficient calculation unit 157 receive standard lateral acceleration information from the standard lateral acceleration calculation unit 152, and the right wheel tire angle calculation unit 153 and the left wheel tire angle calculation unit 154. Tire angle information is acquired from, and the road surface friction coefficient is calculated from the actual lateral acceleration / standard lateral acceleration and the tire angle based on a predetermined map. The map defines the relationship between the actual lateral acceleration / normative lateral acceleration, the tire angle, and the coefficient of friction. This map is determined by, for example, a test or a simulation.

The right wheel road surface friction coefficient calculation unit 155 and the left wheel road surface friction coefficient calculation unit 157 target the right wheel road surface friction coefficient information which is the calculated right wheel road surface friction coefficient and the left wheel road surface friction coefficient information which is the left wheel road surface friction coefficient. It is output to the yaw rate correction unit 158.
The target yaw rate calculation unit 156 calculates a target yaw rate based on the vehicle speed information and the steering angle information acquired from the upper control unit 32, and outputs the calculated target yaw rate to the target yaw rate correction unit 158 as the target yaw rate information.

The target yaw rate correction unit 158 acquires the right wheel road surface friction coefficient information, the left wheel road surface friction coefficient information, and the target yaw rate information, and the road surface represented by the right wheel road surface friction coefficient information and the left wheel road surface friction coefficient information. The target yaw rate is corrected according to the coefficient of friction. The target yaw rate correction unit 158 outputs the corrected target yaw rate as corrected yaw rate information to the target left and right wheel tire angle calculation unit 159.

The target left and right wheel tire angle calculation unit 159 includes the corrected yaw rate information, the actual yaw rate information θ _y from the upper control unit 32 , the accelerator command value X _A and the brake command value X _B , and the right wheel road surface friction coefficient calculation unit. The right wheel road surface friction coefficient information is acquired from 155, and the left wheel road surface friction coefficient information is acquired from the left wheel road surface friction coefficient calculation unit 157, and the target left and right wheel tire angles, which are the target values of the left and right wheel tire angles, are calculated. The target left and right wheel tire angle calculation unit 159 outputs the calculated target tire angles of the left and right wheels as target tire angle information to the right wheel command value calculation unit 160 and the left wheel command value calculation unit 161.

The right wheel command value calculation unit 160 and the left wheel command value calculation unit 161 receive target tire angle information from the target left and right wheel tire angle calculation unit 159, and the current tire from the right wheel tire angle calculation unit 153 and the left wheel tire angle calculation unit 154. Acquires tire angle information indicating the angle. After acquisition, the right wheel command value calculation unit 160 and the left wheel command value calculation unit 161 compare the target tire angle represented by the target tire angle information with the current tire angle, and the right wheel rolls according to the deviation amount. Right wheel steering amount information and left wheel steering amount information representing the amount of steering of each of the hub unit 1 with a steering function and the hub unit 1 with a steering function of the left wheel are generated. The right wheel command value calculation unit 160 outputs the generated right wheel steering amount information (current command signal) to the actuator drive control unit 31 for the right wheel. The left wheel command value calculation unit 161 outputs the generated left wheel steering amount information (current command signal) to the actuator drive control unit 31 for the left wheel.

Each actuator drive control unit 31 outputs a current corresponding to the current command signal input from the right wheel command value calculation unit 160 and the left wheel command value calculation unit 161 to drive and control the steering actuator 5 (FIG. 3). .. Specifically, when the right wheel command value calculation unit 160 and the left wheel command value calculation unit 161 input right wheel steering amount information and left wheel steering amount information to the left and right wheel actuator drive control units 31 and 31, in principle. (At normal times), the output signal of the rotation sensor Sb, which is the position information of each motor 26 (FIG. 3) representing the current steering angle of the left and right wheels, is acquired.

Each actuator drive control unit 31 determines a target position of each motor 26 (FIG. 3) based on the right wheel steering amount information and the left wheel steering amount information, and transfers a current flowing to each motor 26 (FIG. 3). It outputs and outputs the steering angle information of the angle sensor Sa, the position sensor Sc, and the rotation sensor Sb of the left and right wheels. That is, the output signals of the rotation sensor Sb, the position sensor Sc, and the angle sensor Sa provided on the left and right hub units 1 and 1 with the steering function are returned to the target left and right wheel tire angle calculation unit 159, and the steering angle of the left and right wheels is returned. Is converted to. The output signal of the rotation sensor Sb is converted into a steering angle in consideration of the reduction ratio of the speed reducer 27 and the like.

The target left and right wheel tire angle calculation unit 159 compares the three converted steering angles with each other in each wheel, and when all match, the rotation sensor Sb, the position sensor Sc, and the angle sensor Sa are all in the normal state. Judgment is made and the drive control of each steering actuator 5 (FIG. 3) is maintained. If there is a discrepancy in any of the steering angles, the target left and right wheel tire angle calculation unit 159 determines that one of the sensors is in an abnormal state, and outputs the abnormality occurrence information to the upper control unit 32 and each actuator drive control unit 31. Output.

As a result, the upper control unit 32 controls to notify the driver of the abnormal state by, for example, a warning light, a warning sound, or the like. At the same time, each actuator drive control unit 31 stops the drive control of each steering actuator 5 (FIG. 3). If only the steering angle converted from one of the sensors does not match the steering angle converted from the other two sensors, stop using the mismatched sensor and use the other sensor. It is also possible to maintain the drive control of each steering actuator 5 (FIG. 3) by using the above.

<Action effect>
According to the hub unit 1 with a steering function described above, the hub unit main body 2 including the hub bearing 15 that supports the wheels 9 can be freely rotated around the steering axis A by driving the steering actuator 5. Can be made to. Therefore, each wheel 9 can be steered independently, and the toe angle of the wheel 9 can be arbitrarily changed according to the traveling condition of the vehicle.
Therefore, it may be used for either a steering wheel such as a front wheel or a non-steering wheel such as a rear wheel. When used for a steering wheel, by installing it on a member whose direction can be changed by the steering device, it is added to the steering by the driver's steering wheel operation, and the left and right wheels are individually or the left and right wheels are interlocked with each other. It is a mechanism to change the steering angle.

Further, when turning, the difference in steering angle between the left and right wheels can be changed according to the traveling speed. For example, the steering geometry can be changed during running, for example, the parallel geometry is used for turning in the high speed range, and the Ackermann geometry is used for turning in the low speed range. Since the steering angle of the wheels can be arbitrarily changed during traveling in this way, it is possible to improve the kinetic performance of the vehicle and to drive stably and safely. Furthermore, by appropriately changing the steering angles of the left and right steering wheels, it is possible to reduce the turning radius of the vehicle during turning and improve the turning performance. Furthermore, even during straight-line driving, by adjusting the amount of toe angle according to each situation, it is possible to make adjustments such as ensuring driving stability without deteriorating fuel efficiency.

In order to control the behavior of the vehicle by changing the steering angle of the wheels 9 in this way, it is necessary to accurately control the steering angle of the wheels.
According to this configuration, in particular, since a plurality of steering angle detecting means S for detecting the rotation angle around the steering axis A of the hub unit main body 2 are provided, any one of the plurality of steering angle detecting means S is provided. Even if one abnormality occurs, it is possible to accurately control the angle of the wheel 9 to a desired angle by using another steering angle detecting means.

Further, even if there are individual differences due to the rigidity of the steering actuator 5, by setting the relationship between the output signals of the plurality of steering angle detecting means S in advance by a test or the like, a minute steering angle range can be set. It is possible to take an accurate steering angle within. Therefore, the maneuverability and stability of the vehicle can be improved.
Since the angle sensor Sa is provided on the steering shaft as one of the plurality of steering angle detecting means S, it is possible to accurately output a minute angle change of the hub bearing 15. This makes it possible to accurately control the angle of the wheel 9 according to a desired angle.

<About other embodiments>
In the first embodiment, as shown in FIG. 2, substantially the entire actuator body 7 is covered with the case 6b, but the present invention is not limited to this example. As another embodiment, for example, the motor 26 of the actuator main body 7 may have a so-called external structure exposed from the case 6b and attached to the outer surface of the case 6b. In this case, an off-the-shelf motor can be used, and the motor can be easily replaced, so that maintainability can be improved.
As another embodiment, the unit support member 3 may be separately configured as a suspension frame component, and the unit support member 3 may be detachably provided on the suspension frame component.

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 limiting. 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.

2 ... Hub unit body 3 ... Unit support member 5 ... Steering actuator 6 ... Knuckle (undercarriage frame parts)
9 ... Wheel 12 ... Suspension device 15 ... Hub bearing 25 ... Linear mechanism 26 ... Motor 29 ... Control device 30 ... Control unit 31 ... Actuator drive control unit S ... Steering angle detection means Sa ... Angle sensor, Sb ... Rotation sensor, Sc ... Position sensor

Claims (5)

A hub unit main body having a hub bearing for supporting the wheels, a unit support member provided on the undercarriage frame component of the suspension device and rotatably supporting the hub unit main body around a steering axis extending in the vertical direction, and the above-mentioned The hub unit main body is provided with a rolling actuator that rotationally drives the hub unit main body around the steering shaft center, and the hub unit main body has a trunnion-shaped mounting shaft portion provided so as to project vertically from the outer periphery of the hub bearing. And, it is supported by the unit support member via bearings provided on the outer periphery of the upper and lower mounting shafts.
A hub unit with a steering function provided with a steering angle detecting means for detecting a rotation angle around the steering axis center of the hub unit main body. In the hub unit with a steering function according to claim 1, the steering angle detecting means is an angle sensor that directly detects the steering angle, and the steering function is provided on the steering axis. With hub unit. A steering system including the hub unit with a steering function according to claim 1 or 2, and a control device for controlling the rolling actuator of the hub unit with a steering function. , A control unit that outputs a current command signal corresponding to a given steering angle command signal, and an actuator drive that outputs a current corresponding to the current command signal input from this control unit to drive and control the rolling actuator. A steering system with a control unit. In the steering system according to claim 3, the steering actuator includes a motor and a linear motion mechanism that converts the rotational output of the motor into a reciprocating linear operation, and the steering angle detecting means is steering. According to the angle sensor that directly detects the angle, the rotation sensor that indirectly detects the steering angle according to the conditions determined from the rotation angle of the motor, and the conditions determined from the position of the linear motion output unit in the linear motion mechanism. Equipped with a position sensor that indirectly detects the steering angle,
The control unit compares the output signals of at least one of the angle sensor, the rotation sensor, and the position sensor with each other, and determines the abnormality of the steering angle detecting means according to the determination criteria. system. A vehicle in which either or both of the front wheels and the rear wheels are supported by using the hub unit with the steering function according to claim 1 or 2.

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