WO2019172091A1

WO2019172091A1 - Hub unit with steering function, and steering system

Info

Publication number: WO2019172091A1
Application number: PCT/JP2019/007940
Authority: WO
Inventors: 佑介大畑; 大場　浩量; 聡宇都宮; 教雄石原
Original assignee: Ntn株式会社
Priority date: 2018-03-05
Filing date: 2019-02-28
Publication date: 2019-09-12
Also published as: JP7049864B2; JP2019151230A

Abstract

Provided are a hub unit with a steering function, a steering system, and a vehicle provided with the hub unit with a steering function, with which it is possible to enhance the maneuverability and stability of a vehicle. The hub unit (1) with a steering function is provided with a hub unit main body (2) including a hub bearing supporting a wheel, a unit support member (3) which is provided on an undercarriage frame member of a suspension device, and which supports the hub unit main body (2) with freedom to rotate about a steering axis extending in the vertical direction, and a rolling actuator (5) which rotationally drives the hub unit main body (2) about the steering axis. The hub unit is provided with a steering angle detecting means for detecting the angle of rotation of the hub unit main body (2) about the steering axis. The steering angle detecting means is provided with an angle sensor (Sa) which directly detects the steering angle, a rotation sensor (Sb) which indirectly detects the steering angle from the angle of rotation of a motor (26), and a position sensor (Sc) which indirectly detects the steering angle from the position of a linear motion output unit of a linear motion mechanism.

Description

Hub unit with steering function and steering system

Related applications

This application claims the priority of Japanese Patent Application No. 2018-038208 filed on Mar. 5, 2018, which is incorporated herein by reference in its entirety as a part of this application.

The present invention relates to 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. The present invention relates to a technique for improving fuel consumption, stabilizing vehicle running performance and improving reliability.

In general vehicles such as automobiles, 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 handle is determined by the initial setting. The vehicle geometry includes (1) “Parallel geometry” where the left and right wheels have the same turning angle, and (2) The turning inner wheel angle is turned larger than the turning outer wheel angle in order to make the turning center one place. Ackermann geometry is known.

The vehicle geometry affects the stability and reliability of running. For example,

Patent Documents

1 and 2 have been proposed regarding a mechanism in which the steering geometry is variable in accordance with the traveling state. In Patent Literature 1, the steering geometry is changed by relatively changing the knuckle arm and the joint position. In Patent Document 2, two motors are used, and both the toe angle and the camber angle can be tilted to an arbitrary angle. Patent Document 3 proposes a four-wheel independent steering mechanism.

JP 2009-226972 A German Patent Application Publication No. 10201206337 JP 2014-061744 A

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

As described above, since a general vehicle steering device is mechanically connected to a wheel, generally only a single fixed steering geometry can be taken, and an intermediate between the Ackermann geometry and the parallel geometry. Often set to static geometry. However, in this case, the difference in steering angle between the left and right wheels is insufficient in the low speed range, the steering angle of the outer wheel is excessive, and the steering angle of the inner wheel is excessive in the high speed range. Thus, if there is an unnecessary bias in the wheel lateral force distribution of the inner and outer wheels, it will cause deterioration of fuel consumption due to worsening of running resistance and early wear of the wheels, and the smoothness of cornering due to the ineffective use of the inner and outer wheels. There is a problem that is damaged.

According to the proposals in

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. However, a motor actuator that obtains a large force enough to change the vehicle geometry in such a portion. 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 change it greatly, that is, to move it greatly.

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 vehicles with four-wheel independent steering, and because the hub bearing is cantilevered with respect to the steering shaft, the rigidity is lowered, and the steering geometry is caused by the occurrence of excessive traveling G. It may change. Moreover, when a reduction gear is provided on the steered shaft, a large amount of power is required. For this reason, although a motor is enlarged, when a motor is enlarged, it will become difficult to arrange | position the whole to the inner peripheral part of a wheel. Moreover, when a reduction gear with a large reduction ratio is provided, the responsiveness deteriorates.

As described above, the conventional mechanism having an auxiliary turning function has a complicated structure because it aims to arbitrarily change the toe angle or the camber angle of the wheel in the vehicle. In addition, it is difficult to ensure rigidity, and it is necessary to increase the size in order to ensure rigidity, resulting in an increase in weight.

In a vehicle, in order to arbitrarily change the toe angle or camber angle of a wheel, a complicated configuration is required and the number of components increases. In order to improve vehicle handling and stability, it is necessary to accurately steer the steering angles of the left and right wheels. Even if a sensor is provided in the steering actuator, there is an individual difference because the rigidity of the actuator is included, and it is difficult to take an accurate steering angle within a minute angle range (about ± 5 deg). Examples of the rigidity include a backlash of a gear, a backlash of a linear motion mechanism, a case rigidity of an actuator, and the like. Further, when the turning angle is controlled by only one sensor, there is a possibility that the running performance of the vehicle may be hindered when the sensor becomes abnormal.

An object of the present invention is to provide a hub unit with a steering function, a steering system, and a vehicle equipped with a hub unit with a steering function that can improve the steering and stability of the vehicle.

A hub unit with a steering function according to the present invention is provided in a hub unit main body having a hub bearing for supporting a wheel and a suspension frame part of a suspension device, and the hub unit main body extends around a turning axis extending in the vertical direction. A unit support member rotatably supported; and a rolling actuator that rotates the hub unit body about the turning axis, and detects a rotation angle of the hub unit around the turning axis. A turning angle detection means is provided.

According to this configuration, the hub unit body including the hub bearing that supports the wheel can be freely rotated around the turning shaft center by driving the turning actuator. For this reason, steering can be performed independently for each wheel, and the toe angle of the wheel can be arbitrarily changed according to the traveling state of the vehicle. Therefore, it may be used for any of the steered wheels such as front wheels and the non-steered wheels such as rear wheels. When used for steered wheels, it is installed on a member whose direction can be changed by the steering device, so that it can be added to the steer by the steering operation of the driver, and the left and right wheels can be individually or linked to the left and right wheels. It is a mechanism that makes a change in the turning angle.

Also, when turning, the rudder angle difference between the left and right wheels can be changed according to the running speed. For example, the steering geometry can be changed during traveling, such as parallel geometry for turning in a high speed range and Ackermann geometry for turning in a low speed range. Thus, since the turning angle of the wheel can be arbitrarily changed during traveling, it is possible to improve the motion performance of the vehicle and travel with high stability and reliability. Furthermore, by appropriately changing the turning angle of the left and right steered wheels, the turning radius of the vehicle in turning traveling can be reduced, and the turning performance can be improved. Furthermore, even during straight running, it is possible to make adjustments such as ensuring running stability without reducing fuel consumption by adjusting the amount of toe angle in accordance with each scene.

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

The turning angle detection means is an angle sensor that directly detects the turning angle, and this angle sensor may be provided on the turning shaft. Thus, when the angle sensor is provided on the steered shaft, a minute angle change of the hub bearing can be accurately output. This makes it possible to accurately control the wheel angle by a desired angle.

A steering system according to the present invention is a steering system including the hub unit with a steering function according to any one of the configurations of the present invention, and a control device that controls the rolling actuator of the hub unit with the steering function. The control device outputs a current command signal corresponding to a given turning angle command signal, and outputs a current corresponding to the current command signal input from the control unit to output the current command signal. An actuator drive control unit for driving and controlling the actuator.

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

The steering actuator includes a motor and a linear motion mechanism that converts a rotational output of the motor into a reciprocating linear motion, and the steering angle detection means includes an angle sensor that directly detects a steering angle, and the motor. A rotation sensor that indirectly detects the turning angle according to a condition determined from the rotation angle of the motor, and a position sensor that indirectly detects the steering angle according to a condition determined from the position of the linear motion output unit in the linear motion mechanism And the control unit compares the output signals of at least any two of the angle sensor, the rotation sensor, and the position sensor with each other, and determines whether the turning angle detection unit is abnormal in accordance with a determined criterion. May be determined. Each of the determined conditions and the determined determination criteria are conditions and determination criteria arbitrarily determined by design, etc., for example, appropriate conditions and determination criteria are determined by one or both of testing and simulation, etc. Determined by seeking.

According to this configuration, the control unit converts the output signals of the plurality of sensors into the turning angles of the wheels, and when all match, the turning angle detection means determines that the turning angle detection means is in a normal state and maintains control. Can do. The control unit may determine that one of the turning angle detection means is in an abnormal state when the turning angles of the wheels do not match.

In the vehicle of the present invention, either or both of the front wheels and the rear wheels are supported using the hub unit with a steering function having any one of the above-described configurations of the present invention. Therefore, each effect mentioned above about the hub unit with a steering function of this invention is acquired. The front wheel is generally a steered wheel, but when the hub unit with a steered function of the present invention is applied to the steered wheel, it is effective for adjusting the toe angle during traveling. The rear wheels are generally non-steered wheels, but when applied to non-steered wheels, the minimum turning radius during low-speed traveling can be reduced by slightly turning the non-steered wheels.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.
It is a longitudinal cross-sectional view which shows the structure of the hub unit with a steering function which concerns on 1st Embodiment of this invention, and its periphery. It is a horizontal sectional view showing the hub unit with the same turning function and the surrounding configuration. It is a perspective view which shows the external appearance of the hub unit with the same steering function. It is a side view of the hub unit with the same steering function. It is a top view of the hub unit with the same steering function. It is a partial enlarged view of a part of FIG. 5A. FIG. 6 is a sectional view taken along line VI-VI in FIG. 4. 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 apparatus which controls the actuator for steering of the hub unit with the same steering function. It is a schematic plan view of an example of a vehicle to which the hub unit with a steering function of the embodiment is applied.

<First Embodiment>
A hub unit with a turning function according to a first embodiment of the present invention will be described with reference to FIGS.
<Schematic structure of the hub unit 1 with a 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. And detecting means S (FIGS. 5A and 5B). The unit support member 3 is provided integrally with a knuckle 6 that is a suspension frame part. An actuator main body 7 of the steering actuator 5 is provided on the inboard side of the unit support member 3, and a hub unit main body 2 is provided on the outboard side of the unit support member 3. With the hub unit 1 with a steering function mounted on the vehicle, the vehicle width direction outer side of the vehicle is referred to as an outboard side, and the vehicle width direction center side of the vehicle is referred to as an inboard side.

2 and 3, the hub unit main body 2 and the actuator main body 7 are connected by a joint portion 8. Usually, the joint portion 8 is provided with a boot (not shown) for waterproofing and dustproofing.

As shown in FIG. 1, the hub unit main body 2 is supported by the unit support member 3 via the rotation

allowable support parts

4 and 4 at two upper and lower positions so as to be rotatable around the turning axis A extending in the vertical direction. Has been. The turning axis A is an axis different from the rotation axis O of the wheel 9 and is different from a kingpin axis that performs main turning. 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 traveling. The hub unit 1 with a steering function of this embodiment is different from the kingpin angle. It has a turning shaft with an angle (axis). The wheel 9 includes a wheel 9a and a tire 9b.

<Installation location of hub unit 1 with steering function>
This steering function with the hub unit 1 is steered wheels in this embodiment. Specifically, as shown in FIG. 9, the right and left wheels individually small in addition to turning by front wheels 9 _F of the steering device 11 of the vehicle 10 As a mechanism for turning a small angle (about ± 5 deg), the mechanism is provided integrally with the knuckle 6 which is a suspension frame part of the suspension device 12.

As shown in FIG. 2, the steering device 11 is a device that steers the wheel 9 in response to an operation of a handle (not shown). FIG. 2 is a horizontal sectional view of the undercarriage as seen from above. An ordinary vehicle steering device 11 is connected to a steering coupling portion 6d (described later) of the steering function hub unit 1 via a tie rod 14, and the wheel 9 is steered by a driver's handle operation. Making it possible. In addition to this, the hub unit 1 with a turning function may be used as a mechanism for turning the rear wheel 9 _R (FIG. 9) as an auxiliary to the front wheel turning. As the suspension device 12 (FIG. 9), any of a strut suspension mechanism, a multi-link suspension mechanism, and other suspension mechanisms is applied.

<About hub unit body 2>
As shown in FIG. 1, the hub unit body 2 includes a hub bearing 15 for supporting the wheels 9, an outer ring 16, and an auxiliary turning force receiving portion 17 (FIG. 3) described later. As shown in FIG. 6, the hub bearing 15 includes an inner ring 18, an outer ring 19, and rolling elements 20 such as balls interposed between the inner and

outer rings

18, 19. 1).

In the illustrated example, the hub bearing 15 is an angular ball bearing in which the outer ring 19 is a fixed ring, the inner ring 18 is a rotating ring, and the rolling elements 20 are in a double row. The inner ring 18 includes a hub ring portion 18a having a hub flange 18aa and constituting a race surface on the outboard side, and an inner ring portion 18b constituting a race 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 around the rotation axis O.

As shown in FIG. 6, the outer ring 16 includes an annular portion 16 a fitted to the outer peripheral surface of the outer ring 19, and a trunnion shaft-like mounting shaft portion provided so as to protrude vertically from the outer periphery of the annular portion 16 a. 16b, 16b. Each attachment shaft portion 16 b is provided coaxially with the turning 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 mounted on two upper and lower brake caliper mounting portions 22 (FIG. 4) formed integrally with the outer ring 19 so as to project into an arm shape.

<About the rotation-supporting support component 4 and the unit support member 3>
As shown in FIG. 6, each rotation-allowing support component 4 includes a rolling bearing. In this example, a tapered roller bearing is applied as the rolling bearing. 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 includes a unit support member main body 3A and a unit support member combined body 3B. A substantially ring-shaped unit support member assembly 3B is detachably fixed to the end of the unit support member main body 3A on the outboard side. Partial concave spherical fitting hole forming portions 3a are respectively formed on the upper and lower portions of the side surface of the inboard side of the unit support member assembly 3B.

As shown in FIGS. 5A and 6, partial concave spherical fitting hole forming portions 3Aa are respectively formed on the upper and lower portions of the outboard side end of the unit support member main body 3A. As shown in FIG. 3, the unit support member assembly 3B is fixed to the end of the unit support member main body 3A on the outboard side, and the fitting hole forming portions 3a and 3Aa (FIG. 5A) are combined with each other for each upper and lower part. As a result, a fitting hole is formed continuously around the entire circumference. In FIG. 3, the unit support member 3 is indicated by a one-dot chain line. As shown in FIG. 6, the outer ring 4b is fitted in the fitting hole.

Each mounting shaft portion 16b is formed with a female screw portion extending in the radial direction, and is provided with a bolt 23 that is screwed into the female screw portion. A disc-like pressing member 24 is interposed on the end surface of the inner ring 4a, and a preload is applied to each rotation-allowing support component 4 by applying a pressing force to the end surface of the inner ring 4a by a bolt 23 that is screwed into the female screw portion. Giving. Thereby, the rigidity of each rotation permission support component 4 can be improved. The rolling bearing of the rotation-allowing support component 4 may be an angular ball bearing or a four-point contact ball bearing instead of the tapered roller bearing. In such a case as well, a preload can be applied in the same manner as described above.

As shown in FIG. 2, the auxiliary turning force receiving portion 17 is a portion that serves as an action point for applying the auxiliary turning force to the outer ring 19 of the hub bearing 15, and is an arm that projects integrally with a part of the outer periphery of the outer ring 19. It is provided as a part. The auxiliary turning force receiving portion 17 is rotatably connected to the linear motion output portion 25 a of the turning actuator 5 via the joint portion 8. As a result, when the linear motion output portion 25a of the steering actuator 5 advances and retreats, the hub unit main body 2 rotates around the turning axis A (FIG. 1), that is, is auxiliary-steered.

<Steering actuator 5>
As shown in FIG. 3, the steering actuator 5 includes an actuator body 7 that drives the hub unit body 2 to rotate about the turning axis A (FIG. 1). As shown in FIG. 2, the actuator body 7 converts a motor 26, a speed reducer 27 that decelerates the rotation of the motor 26, and a forward / reverse rotation output of the speed reducer 27 into a reciprocating linear motion of the linear motion output unit 25a. And a linear motion mechanism 25. The motor 26 is, for example, a permanent magnet type synchronous motor, but may be a DC motor or an induction motor.

The reduction gear 27 can use a wrapping transmission mechanism such as a belt transmission mechanism or a gear train, and a belt transmission mechanism is used in the example of FIG. The reducer 27 includes a drive pulley 27a, a driven pulley 27b, and a belt 27c. A drive pulley 27 a is coupled to the motor shaft of the motor 26, and a driven pulley 27 b is provided in the linear motion mechanism 25. The driven pulley 27b is disposed in 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. In this example, a feed screw mechanism using a trapezoidal screw slide screw is used. Since the linear motion mechanism 25 includes a feed screw mechanism that uses a sliding screw of the trapezoidal screw, the effect of preventing reverse input from the tire 9b can be enhanced. The actuator 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 using a reduction gear 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 6 b is formed in a bottomed cylindrical shape, and is provided with a motor housing portion that supports the motor 26 and a linear motion mechanism housing portion that supports the linear motion mechanism 25. A fitting hole for supporting the motor 26 at a predetermined position in the case is formed in the motor housing portion. The linear motion mechanism accommodating portion is formed with a fitting hole for supporting the linear motion mechanism 25 at a predetermined position in the case, a through hole for allowing the linear motion output portion 25a to advance and retreat.

As shown in FIG. 3, the unit support member main body 3A includes the case 6b, a shock absorber mounting portion 6c serving as a shock absorber mounting portion, and a steering device coupling portion 6d serving as a coupling 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. A shock absorber mounting portion 6c is formed on the upper portion of the outer surface portion of the unit support member main body 3A so as to protrude. A steering device coupling portion 6d is formed on the side surface portion of the outer surface portion of the unit support member main body 3A so as to protrude.

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

As shown in FIG. 5B, the encoder Saa in 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. In addition, 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 a target left and right wheel tire angle calculation unit 159 (FIG. 8) to 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 turning angle is calculated based on the number of pulses.

6 and 7, the plurality of turning angle detection means S includes a rotation sensor Sb and a position sensor Sc that indirectly detect the turning angle. As shown in FIG. 6, the rotation sensor Sb detects and outputs a signal representing a relative rotation angle between the stator and the rotor of the motor 26. The rotation sensor Sb is disposed in close proximity to the detected portion Sba provided on the outer peripheral surface of the rotation output shaft 26a of the rotor and the detected portion Sba provided in the motor housing portion in the case 6b, for example, facing the detected portion Sba. 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 turning angle and controlling the rotation of the motor 26.

As shown in FIG. 7, the position sensor Sc indirectly detects the turning angle according to a condition determined from the position of the linear motion output unit 25 a in the linear motion mechanism 25. For example, a magnetic sensor is applied to the position sensor Sc. The position sensor Sc has a magnetic target and a magnetic sensor unit Sca. The magnetic target is composed of 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 housing unit in the case 6b. The magnetic sensor unit Sca is disposed so as to face the magnetic target at a predetermined position in the radial direction. For example, a Hall IC or the like is applied as the magnetic sensor unit Sca. 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, the steering system includes the hub unit 1 with a steering function and a control device 29 that controls the steering actuator 5 of the hub unit 1 with the steering function. The control device 29 includes a control unit 30 and an actuator drive control unit 31. The control unit 30 outputs at least one of the angle sensor Sa, the rotation sensor Sb (FIG. 8), and the position sensor Sc (FIG. 8), and the auxiliary turning angle command signal (the rotation control signal) given from the host control unit 32. A current command signal corresponding to the steering angle command signal e is output.

The upper control unit 32 is an upper control means of the control unit 30, and an electric control unit (Vehicle Control Unit, abbreviated as VCU) for controlling the entire vehicle is applied as the upper control unit 32, for example. 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 control unit 30. The actuator drive control unit 31 configures, for example, a half bridge circuit using a switching element (not shown), and performs PWM control for determining a motor applied voltage based on the ON-OFF duty ratio of the switching element. Thereby, in addition to the steering by a driver | operator's steering wheel operation, a wheel can change a small angle. Even when running straight, the amount of toe angle can be adjusted to suit each scene.

<Detailed Configuration of Control Unit 30>
As shown in FIG. 8, the control unit 30 includes a reference 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, a left wheel. 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 are provided.

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 host control unit 32 at 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 which the steering system turns 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 reference lateral acceleration calculation unit 152.

The standard lateral acceleration calculation unit 152 calculates the standard lateral acceleration based on the vehicle speed information acquired from the host control unit 32 and the tire angle information. That is, the reference lateral acceleration calculation unit 152 calculates the reference 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. Perform the calculation. The reference lateral acceleration calculation unit 152 outputs the calculated reference lateral acceleration as reference 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 road 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 host 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 the reference lateral acceleration information from the reference lateral acceleration calculation unit 152, the right wheel tire angle calculation unit 153, and the left wheel tire angle calculation unit 154. Tire angle information is obtained from the vehicle, and a road surface friction coefficient is calculated from the actual lateral acceleration / reference lateral acceleration and the tire angle based on a predetermined map. In the map, the relationship between the actual lateral acceleration / reference lateral acceleration, the tire angle, and the friction coefficient is defined. This map is determined by testing or simulation, for example.

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 that is the calculated road surface friction coefficient of the right wheel and the left wheel road surface friction coefficient information that is the road surface friction coefficient of the left wheel. The data 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 host control unit 32, and outputs the calculated target yaw rate to the target yaw rate correction unit 158 as 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 is 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 friction coefficient. The target yaw rate correction unit 158 outputs the corrected target yaw rate to the target left and right wheel tire angle calculation unit 159 as corrected yaw rate information.

Target right wheel tire angle calculation unit 159, and the corrected yaw rate information actual yaw rate information from the host control unit 32 [theta] y, and the accelerator command value X _A and braking command value X _B, right from the right wheel road surface friction coefficient calculator 155 The left wheel road surface friction coefficient information is obtained from the wheel road surface friction coefficient information and the left wheel road surface friction coefficient calculation unit 157, and the target left and right wheel tire angles that are target values of the tire angles of the left and right wheels 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 to the right wheel command value calculation unit 160 and the left wheel command value calculation unit 161 as target tire angle information.

The right wheel command value calculation unit 160 and the left wheel command value calculation unit 161 receive the 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, respectively. Tire angle information representing an angle is acquired. After the 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 change the right wheel according to the deviation amount. The right wheel turning amount information and the left wheel turning amount information representing the amount of turning of each of the hub unit with rudder function 1 and the hub unit with left wheel turning function 1 are generated. The right wheel command value calculation unit 160 outputs the generated right wheel steering amount information (current command signal) to the right wheel actuator drive control unit 31. The left wheel command value calculation unit 161 outputs the generated left wheel turning amount information (current command signal) to the left wheel actuator drive control unit 31.

Each actuator drive control unit 31 drives and controls the steering actuator 5 (FIG. 3) by outputting 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. . Specifically, the right and left wheel actuator

drive control units

31 and 31 receive the right wheel turning amount information and the left wheel turning amount information from the right wheel command value calculation unit 160 and the left wheel command value calculation unit 161 in principle. (When normal), an output signal of the rotation sensor Sb, which is position information of each motor 26 (FIG. 3) indicating the current turning 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 turning amount information and the left wheel turning amount information, and supplies a current to be supplied to each motor 26 (FIG. 3). The steering angle information of the angle sensor Sa, the position sensor Sc and the rotation sensor Sb of the left and right wheels is output. That is, the output signals of the rotation sensor Sb, the position sensor Sc, and the angle sensor Sa provided in the left and

right hub units

1 and 1 with a turning function are returned to the target left and right wheel tire angle calculation unit 159, and the turning angles of the left and right wheels are returned. Is converted to The output signal of the rotation sensor Sb is converted into a turning angle in consideration of the reduction ratio of the reduction gear 27 and the like.

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

Thereby, the upper control unit 32 performs control for notifying the driver of the abnormal state by using, for example, a warning light or a warning sound. At the same time, each actuator drive control unit 31 stops the drive control of each steering actuator 5 (FIG. 3). If only the turning angle converted from one of the sensors is inconsistent with the turning angle converted from the other two sensors, the use of the mismatched sensor is stopped and the other sensor It is also possible to maintain the drive control of each steering actuator 5 (FIG. 3) using.

<Effect>
According to the hub unit 1 with a turning function described above, the hub unit body 2 including the hub bearing 15 that supports the wheel 9 is freely rotated around the turning axis A by driving the turning actuator 5. Can be made. For this reason, steering can be performed independently for each wheel 9, and the toe angle of the wheel 9 can be arbitrarily changed according to the traveling state of the vehicle. Therefore, it may be used for any of the steered wheels such as front wheels and the non-steered wheels such as rear wheels. When used for steered wheels, it is installed on a member whose direction can be changed by the steering device, so that it can be added to the steer by the steering operation of the driver, and the left and right wheels can be individually or linked to the left and right wheels. It is a mechanism that makes a change in the turning angle.

In order to control the behavior of the vehicle by changing the turning angle of the wheel 9 in this way, it is necessary to accurately control the turning angle of the wheel. According to this configuration, in particular, since the plurality of turning angle detection means S for detecting the rotation angle of the hub unit body 2 around the turning axis A is provided, any one of the plurality of turning angle detection means S is provided. Even when an abnormality occurs in one, the angle of the wheel 9 can be accurately controlled to a desired angle by using another turning angle detection means.

Even if there is an individual difference due to the rigidity of the steering actuator 5, the relationship between the output signals of the plurality of steering angle detection means S is set in advance by a test or the like, so that a small range of the steering angle can be obtained. It is possible to take an accurate steering angle. Therefore, the handling and stability of the vehicle can be improved. As one of the plurality of turning angle detection means S, since the angle sensor Sa is provided on the turning shaft, a minute angle change of the hub bearing 15 can be accurately output. As a result, the angle of the wheel 9 can be accurately controlled by 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, a so-called external structure in which the motor 26 of the actuator body 7 is exposed from the case 6b and attached to the outer surface of the case 6b may be employed. In this case, an off-the-shelf motor can be used, and maintenance can be improved, for example, the motor can be easily replaced. As another embodiment, the unit support member 3 may be configured separately from the underbody frame part, and the unit support member 3 may be detachably provided on the underbody frame part.

As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily understand various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims.

DESCRIPTION OF SYMBOLS 1 ... Hub unit with a steering function 2 ... Hub unit main body 3 ... Unit support member 5 ... Actuator for steering 6 ... Knuckle (suspension frame parts)
DESCRIPTION OF SYMBOLS 9 ... Wheel 12 ... Suspension apparatus 15 ... Hub bearing 25 ... Linear motion mechanism 26 ... Motor 29 ... Control apparatus 30 ... Control part 31 ... Actuator drive control part S ... Steering angle detection means Sa ... Angle sensor Sb ... Rotation sensor Sc ... Position sensor

Claims

A hub unit main body having a hub bearing for supporting a wheel, a unit support member provided on a suspension frame part of a suspension device, and rotatably supporting the hub unit main body around a turning axis extending in the vertical direction; A rolling actuator that rotates the hub unit body about the turning axis, and
A hub unit with a turning function, comprising a turning angle detection means for detecting a rotation angle of the hub unit body around the turning axis.
The hub unit with a turning function according to claim 1, wherein the turning angle detection means is an angle sensor that directly detects a turning angle, and the turning function in which the angle sensor is provided on the turning shaft. With hub unit.
A steering system comprising: the hub unit with a steering function according to claim 1 or 2; and a control device that controls the rolling actuator of the hub unit with the steering function. A control unit that outputs a current command signal according to a given turning angle command signal, and an actuator drive that drives and controls the rolling actuator by outputting a current according to the current command signal input from the control unit A steering system having a control unit.
4. The steering system according to claim 3, wherein the steering actuator includes a motor and a linear motion mechanism that converts a rotational output of the motor into a reciprocating linear motion, and the steering angle detection means includes An angle sensor that directly detects the angle, a rotation sensor that indirectly detects the steering angle according to a condition determined from the rotation angle of the motor, and a condition determined from the position of the linear motion output unit in the linear motion mechanism A position sensor for indirectly detecting the turning angle,
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 whether the steering angle detection unit is abnormal according to a predetermined criterion. system.
A vehicle in which one or both of the front wheels and the rear wheels are supported by using the hub unit with a steering function according to claim 1 or 2.