JP2020142630A - Hub unit with steering function and vehicle with the same - Google Patents

Abstract

To provide a hub unit with a steering function such that the hub unit can be made compact on the whole and a movement quantity of an output rod of a direct-acting mechanism can be accurately monitored, and a vehicle with the same.SOLUTION: A steering actuator 5 of a hub unit 1 with a steering function has a motor 26, and a direct-acting mechanism 25 which converts rotation output of the motor 26 into direct-acting motion of an output rod 25a, and as the output rod 25a moves forward and backward, a hub unit body 2 is driven to rotate on a turning axis A. The direct-acting mechanism 25 has a rotation stop component 43, stopping the output rod 25a from rotating, fitted to the output rod 25a to come into slidable contact with a fixed part of the direct-acting mechanism 25, and the rotation stop component 43 is provided with a measurement target Tg for position sensor. A position sensor 44 which detects displacement of the measurement target Tg for position sensor as a movement quantity of the output rod 25a is positioned at the fixed part.SELECTED DRAWING: Figure 2

Description

The present invention aims to improve fuel efficiency, stabilize driving performance, and improve safety by controlling the left and right wheels to appropriate steering angles according to the driving conditions with respect to a hub unit with a steering function and a vehicle equipped with the hub unit. Regarding technology.

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 cutting 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 cutting 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. Ackermann geometry is known.

Ackerman 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 turn the vehicle smoothly when turning in a low speed range where the centrifugal force acting on the vehicle can be ignored. Is set. However, in high-speed turning where centrifugal force cannot be ignored, it is desirable that the wheels generate cornering force in a direction that balances with centrifugal force, so parallel geometry is preferable to 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 the Ackermann geometry and the parallel geometry. Often set to a typical geometry. However, in this case, the difference between the steering angles of the left and right wheels is insufficient in the low speed range, the steering angle of the outer wheels becomes excessive, and the steering angle of the inner wheels becomes excessive in the high speed range. 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 tires, and the inner and outer wheels cannot be used efficiently, so that cornering smoothness is improved. There is a problem that it is damaged.

Therefore, the applicant has proposed a hub unit with a steering function (Patent Document 3) that can perform auxiliary steering for each wheel according to a driving situation in addition to steering by operating the steering wheel of the driver.

German Patent Application Publication No. 1020122036337 Japanese Unexamined Patent Publication No. 2014-061744 JP-A-2019-006226

In Patent Document 1, since two motors are used, not only the cost increases due to the increase in the number of motors, but also the control becomes complicated.
In Patent Document 2, since the hub bearing is cantilevered and supported with respect to the steering shaft, the rigidity is lowered, and the steering geometry may change due to the occurrence of excessive traveling G.
Further, when the reduction gear is provided on the steering shaft, the size including the motor becomes large. As the size of the motor or the like increases, it becomes difficult to arrange the entire motor 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 is intended to arbitrarily change the toe angle or camber angle of the wheels in the vehicle, so that a plurality of motors and reduction mechanisms are required, which is a complicated configuration. It has become. In addition, it becomes difficult to secure the rigidity, and in order to secure the rigidity, it is necessary to increase the size and become heavy.
In addition, when the kingpin axis and the steering axis of the mechanism having the auxiliary steering function match, the overall size becomes large and heavy because the component parts are arranged behind the hub unit (on the vehicle body side). ..

The hub unit with a steering function has a motor and a linear motion mechanism that converts the rotational output of the motor into a linear motion of the output rod, and when the output rod advances and retreats, the hub unit main body rotates around the steering axis. (Patent Document 3).
The accuracy of the linear motion mechanism is ensured by inputting the position information to the control unit and performing feedback control. It is possible to use the rotation angle sensor output of the motor as the position information, but there is an error with respect to the actual movement of the linear motion mechanism due to the backlash and elastic deformation of the trapezoidal screw of the linear motion mechanism. If a separate sensor that directly measures the actual movement of the linear motion mechanism is provided, space is required, and the entire hub unit becomes large by that space, which may interfere with other parts such as the suspension.

An object of the present invention is to provide a hub unit with a steering function capable of accurately monitoring the amount of movement of the output rod of the linear motion mechanism while reducing the size of the entire hub unit, and a vehicle provided with the hub unit. ..

The hub unit with steering function of the present invention includes a hub unit body having a hub bearing that supports wheels, and a hub unit body.
A unit support member provided on the suspension frame component of the suspension device and rotatably supporting the hub unit body around the steering axis extending in the vertical direction.
A steering actuator for rotationally driving the hub unit body around the center of the steering axis is provided.
The steering actuator has a rotary drive source and a linear motion mechanism that converts the rotational output of the rotary drive source into a linear motion of the output rod, and the hub unit main body is moved by moving the output rod forward and backward. A hub unit with a steering function that is rotationally driven around the center of the steering shaft.
In the linear motion mechanism, a detent component for detenting the output rod is attached to the output rod and slidably contacts a fixed portion of the linear motion mechanism, and the detent component is used for a position sensor. A measurement target is provided, and a position sensor for detecting the displacement of the position sensor measurement target, which is the amount of movement of the output rod, is provided in the fixed portion.

According to this configuration, the output rod of the linear motion mechanism moves forward and backward, so that the hub unit main body is rotationally driven around the center of the steering shaft to be steered. At this time, by sensing the amount of movement of the output rod with the position sensor, the angle of the wheel is appropriate in the path of transmitting the driving force from the rotational drive source to the linear motion mechanism and without being affected by the play of the linear motion mechanism itself. It can be managed accurately and accurately, or it can be confirmed whether the linear motion mechanism is operating according to the command value. In addition, since the measurement target for the position sensor is provided in the detent component that detents the output rod, the space can be reduced compared to installing the measurement target for the position sensor separately in the dedicated component, and the hub unit. The whole can be miniaturized.

The position sensor may be a magnetic sensor, and the measurement target for the position sensor may be a permanent magnet. The magnetic sensor does not require a light source or the like, has a simple structure, and has excellent durability in an environment subject to vibration during traveling. Further, since the measurement target for the position sensor is a permanent magnet, the magnetic sensor can read the change in the magnetic field of the permanent magnet and accurately detect the movement amount of the output rod.

The linear motion mechanism may have a nut portion rotatably supported by the unit support member and the output rod provided with a male screw portion that meshes with a female thread portion of the nut portion on the outer circumference. In this case, by rotating the nut portion, the derotated output rod can be freely moved forward and backward.

The steering system of the present invention includes a hub unit with a steering function having any of the above configurations of the present invention and a control device, and the control device outputs a command signal of an upper control unit and a position sensor output from the position sensor. A steering control unit that receives and outputs a current command signal to the motor serving as the rotation drive source, and a steering control unit that outputs a current corresponding to the current command signal and applies it to the motor to drive the steering actuator.
According to this configuration, the hub unit with a steering function of the present invention can be controlled with a simple configuration, and the above-mentioned advantages of the hub unit with a steering function can be effectively obtained.

In the vehicle of the present invention, one or both of the front wheels and the rear wheels are supported by using the 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 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 main body having a hub bearing for supporting wheels and a suspension frame component of a suspension device, and rotates the hub unit main body around a steering axis extending in the vertical direction. A unit support member that freely supports the hub unit and a steering actuator that rotationally drives the hub unit body around the steering axis center are provided. The steering actuator includes a rotational drive source and a rotational output of the rotational drive source. It is a hub unit with a steering function that has a linear motion mechanism that converts the output rod into a linear motion of the output rod, and the hub unit body is rotationally driven around the steering axis center by moving the output rod forward and backward. In the linear motion mechanism, the detent component for detenting the output rod is attached to the output rod and slidably contacts the fixed portion of the linear motion mechanism, and is located at the detent component. A measurement target for the sensor is provided, and a position sensor for detecting the displacement of the measurement target for the position sensor, which is the amount of movement of the output rod, is provided in the fixed portion. Therefore, it is possible to reduce the size of the entire hub unit and accurately monitor the amount of movement of the output rod of the linear motion mechanism.

The steering system of the present invention includes a hub unit with a steering function having any of the above configurations of the present invention and a control device, and the control device outputs a command signal of a host control unit and a position sensor output from the position sensor. A steering control unit that receives and outputs a current command signal to the motor that is the rotation drive source, and a hub unit as a whole to output a current corresponding to the current command signal and apply it to the motor to drive the steering actuator. It is possible to accurately monitor the amount of movement of the output rod of the linear motion mechanism while reducing the size of the motor.

In the vehicle of the present invention, one or both of the front wheels and the rear wheels are supported by using the hub unit with a steering function having any of the above configurations of the present invention, so that the entire hub unit can be miniaturized and directly. The amount of movement of the output rod of the moving mechanism can be accurately monitored.

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 periphery. It is a perspective view which shows the appearance of the hub unit with a steering function. It is a perspective view which shows the appearance of the hub unit with a steering function. It is a side view of the hub unit with the steering function. It is a top view of the hub unit with the steering function. FIG. 4 is a sectional view taken along line VI --VI of FIG. It is a side view which shows the detent part of the output rod of the hub unit with a steering function partially. FIG. 5 is an enlarged cross-sectional view showing a part of FIG. 2 in an enlarged manner. It is explanatory drawing of the conceptual structure of the position sensor used for the hub unit with a steering function. It is a schematic plan view of an example of a vehicle equipped with the hub unit with a steering function. It is a schematic plan view of another example of the vehicle provided with any of the hub units with steering functions. FIG. 3 is a schematic plan view of another example of a vehicle provided with any of the steering function hub units.

[First Embodiment]
A hub unit with a steering function according to an embodiment of the present invention will be described with reference to FIGS. 1 to 10.
<Outline structure of hub unit with steering function>
As shown in FIG. 1, the hub unit 1 with a steering function includes a hub unit main body 2, a unit support member 3, a rotation allowable support component 4, and a steering actuator 5. A unit support member 3 is integrally provided with the knuckle 6, which is a suspension frame component. The actuator body 7 of the steering actuator 5 is provided on the inboard side of the unit support member 3, and the hub unit body 2 is provided on the outboard side of the unit support member 3. With the hub unit 1 with steering function mounted on the vehicle, 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. The hub unit 1 with a steering function may be simply referred to as a hub unit 1.

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 a steering function of this embodiment has an angle different from the kingpin angle. It has a (axis) steering shaft. 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 of the steering wheels, specifically, the steering device 11 of the front wheels 9F of the vehicle 10, as shown in FIG. As a mechanism for steering (about ± 5 deg), it is integrally provided with the knuckle 6 of the suspension device 12. However, in the hub unit 1 with a steering function of the steering wheels, depending on the demand of vehicle control, the left and right wheels may individually take a relatively large angle such as 10 ° to 20 ° in addition to the minute angle. The same applies to the hub unit 1 with a steering function shown in FIG. 12, which will be described later.

As shown in FIGS. 2 and 10, the steering device 11 is attached to the vehicle body and is operated by the operation of the steering wheel 11a of the driver or a command of an automatic driving device or a driving support device (not shown), and the tie rods move forward and backward. 14 is connected to the steering coupling portion 6d (described later) of the unit support member 3. The steering device 11 is a rack and pinion type or the like, but any type of steering device may be used. For example, the suspension device 12 applies a strut type suspension mechanism that directly fixes the shock absorber to the knuckle 6, but a double wishbone type suspension mechanism, a multi-link type suspension mechanism, and other suspension mechanisms may be applied. ..

<About hub unit body 2>
As shown in FIG. 1, the hub unit main body 2 includes a hub bearing 15 for supporting the wheel 9, an outer ring 16, and an arm portion 17 (FIG. 3) which is a steering force receiving portion 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 plays the role of connecting 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 steering shaft provided so as to project vertically from the outer circumference of the annular portion 16a. It has parts 16b and 16b. Each of the steering shaft portions 16b, which are the upper and lower mounting shaft portions, is provided coaxially with the steering axis 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 integrally projecting from 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 a rolling bearing. In this example, tapered roller bearings are applied as rolling bearings. The rolling bearing has an inner ring 4a fitted to the outer periphery of the steering shaft portion 16b, an outer ring 4b fitted to the unit support member 3, and a plurality of rolling elements 4c interposed between the inner and outer rings 4a and 4b. ..

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. Partial concave spherical fitting hole forming portions 3Ba are formed on the upper and lower portions of the inboard side side surface of the unit support member coupling 3B.

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

As shown in FIG. 6, each steering shaft portion 16b is formed as a hollow shaft so that a female screw portion extends in the inner peripheral hole in the radial direction, and a bolt 23 screwed to the female screw portion is provided. There is. 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 screw portion to apply a preload to each rotation allowable support component 4. Giving. That is, the initial preload is set so that the preload does not come off even when an external force such as the weight of the vehicle acts on the hub unit. 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, a preload can be applied in the same manner as described above.

As shown in FIG. 1, the upper and lower steering shaft portions 16b and 16b are supported by the unit support member 3 via the rotation allowable support parts 4 and 4, respectively, and each rotation allowable support component 4 is inside the wheel 9a of the wheel 9. Located in. In this example, each rotation allowable support component 4 is arranged in the wheel 9a near the middle in the width direction of the wheel 9a.

As shown in FIG. 2, the arm 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 projects integrally with the outer ring 16 or a part of the outer circumference of the outer ring 19. .. The arm portion 17 is rotatably connected to the output rod 25a, which is the linear output portion of the steering actuator 5, via the joint portion 8. As a result, the output rod 25a of the steering actuator 5 advances and retreats (straight movement), so that the hub unit main body 2 rotates around the steering axis A, that is, auxiliary steering is performed.

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

<Reducer 27>
As the speed reducer 27, a winding type transmission mechanism such as a belt transmission mechanism or a gear train or the like can be used, and the belt transmission mechanism is used in the example of FIG. The speed reducer 27 has a drive pulley 27a, a driven pulley 27b, and a belt 27c. The drive pulley 27a is coupled to the motor shaft of the motor 26, and the driven pulley 27b is provided on the rotatable nut portion 35 of 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.

<About the linear motion mechanism 25>
As shown in FIGS. 2 and 8, the linear motion mechanism 25 can use a slide screw type feed screw mechanism such as a trapezoidal screw or a triangular screw. In this example, the feed screw mechanism using a trapezoidal screw slide screw is used. 33 is used. Grease is sealed inside the sliding screw. The linear motion mechanism 25 includes a feed screw mechanism 33, a rotary support bearing 28, a detent component 43, and an actuator case 34 which is a cover for covering these components.

The feed screw mechanism 33 has a nut portion 35, the output rod 25a which is a screw shaft, and a slide bearing 37. The output rod 25a is detented to the unit support member 3 by a detent component 43 described later. The nut portion 35 is provided with a driven pulley 27b in the axially intermediate portion of the outer peripheral portion, and is rotatably supported by the unit support member 3 by the rotary support bearings 28 and 28 on both sides in the axial direction. A female screw portion 35a is provided on the inner circumference of the nut portion 35. On the outer circumference of the output rod 25a, a male screw portion 25aa that meshes with the female screw portion 35a of the nut portion 35 is provided.

Slide bearings 37 and 37 through which the output rod 25a slidably penetrates are provided at both ends of the nut portion 35 in the axial direction. Each plain bearing 37 guides the axial movement of the output rod 25a and prevents the output rod 25a from being loaded with a radial force when an external force from the tire side is input to the output rod 25a. ..

As the rotary support bearing 28, in this example, two tapered roller bearings are combined face-to-face via a driven pulley 27b. The arrangement of these rotary support bearings 28, 28 may be either back-aligned or front-aligned, but the front-aligned arrangement is preferable in terms of ease of assembly and preload adjustment by shims and the like.

Each rotary support bearing 28 includes an outer ring 28a which is a fixed ring, an inner ring 28b which is a rotary ring, a plurality of rolling elements 28c interposed between the inner and outer rings 28b, 28a, and a cage 28d holding these rolling elements 28c. Has. Each inner ring 28b is fitted and fixed to the outer peripheral surface of the nut portion 35, and is regulated in the axial direction by the retaining rings 39 and 39. The outer ring 28a of the rotary support bearing 28 on the outboard side is fitted and fixed in the fitting hole of the case 6b, and the outer ring 28a of the rotary support bearing 28 on the inboard side is on the inner peripheral surface of the actuator case 34 on the outboard side. It is fitted and fixed. The rotary support bearing 28 may be an angular contact ball bearing. Also in this case, the rotation support bearings 28, 28 may be arranged in either the back surface alignment or the front surface alignment.

As shown in FIGS. 7 and 8, the detent component 43 is a shaft-shaped member provided at the inboard side end portion which is the rear end portion of the output rod 25a. The detent component 43 is fitted and fixed to the output rod 25a in a penetrating manner so as to extend in the vertical direction and in the directions orthogonal to the axial direction of the output rod 25a at the inboard side end of the output rod 25a. .. An annular slide bearings 49a and 49b are fitted to both ends in the axial direction on the outer circumference of the detent component 43.

A flat surface (so-called D-cut surface) 50 parallel to one end surface of the slide bearing 49b is formed at a portion of the end of the output rod 25a on the inboard side facing the lower slide bearing 49b. One end surface of the slide bearing 49b is brought into contact with the flat surface 50 of the output rod 25a, and a bolt 51 for pressing the other end surface of the lower slide bearing 49b is screwed into the detent component 43. As a result, the vertical positions of the detent component 43, the bolt 51, and the slide bearings 49a and 49b are restricted to desired positions with respect to the actuator case 34. A measurement target Tg for a position sensor, which will be described later, is embedded in the bolt 51.

A substantially rectangular parallelepiped guide groove 52 including guide surfaces 52a and 52b for guiding the outer peripheral surfaces of the slide bearings 49a and 49b is formed in the actuator case 34. In other words, the anti-rotation component 43 slidably contacts the guide surfaces 52a and 52b of the actuator case 34, which is a fixed portion of the linear motion mechanism 25, via the slide bearings 49a and 49b. Therefore, the output rod 25a can be reciprocated in the axial direction by sliding the detent component 43 along the guide groove 52 of the actuator case 34 via the slide bearings 49a and 49b. Further, in order to slide the anti-rotation component 43 via the slide bearings 49a and 49b, at least the guide surfaces 52a and 52b are subjected to, for example, wear prevention treatment. The slide bearings 49a and 49b may be made of a metal such as a copper alloy or a porous sintered alloy, or may be made of a resin such as a fluororesin.

As shown in FIG. 2, 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 subassembly and detachably attached to the case 6b with bolts or the like. A mechanism that directly transmits the driving force of the motor 26 to the linear motion mechanism 25 without going through a speed reducer is also possible.

<About position sensors, etc.>
As shown in FIGS. 7 and 8, the steering actuator 5 includes a position sensor 44, and the position sensor 44 monitors the amount of movement of the output rod 25a in the axial direction. The position sensor 44 is provided in the actuator case 34, which is a fixed portion of the linear motion mechanism 25. The position sensor 44 is fixed to the substrate 53 fixed in the actuator case 34, and the position sensor 44 faces the path in which the measurement target Tg for the position sensor, which will be described later, advances and retreats. Further, when the output rod 25a is in the defined axial position (advance / retreat position), the position sensor 44 and the position sensor measurement target Tg face each other with a defined gap Gp. The defined axial position and the defined gap Gp are axial positions and gaps arbitrarily determined by design and the like, respectively, and are appropriate axial positions according to, for example, one or both of test and simulation. , Determined for the gap.

As conceptually shown in FIG. 9, the position sensor 44 has two semiconductor elements 45 for detecting a change in position in one package 46, and outputs the output of each semiconductor element 45 to the outside of the package 46. The output terminals 47 and 47 are individually provided. As the position sensor 44, various sensors such as a magnetic type, an optical type, and a capacitance type can be used, but in this embodiment, a magnetic sensor is used, and a Hall element is used for each of the semiconductor elements 45. ing.

As shown in FIG. 8, the detent component 43 is provided with a permanent magnet 48 serving as a measurement target Tg for a position sensor. Specifically, the permanent magnet 48 is embedded in the head of the bolt 51 screwed into the detent component 43 at the axial end. The bolt 51 is made of a non-magnetic material such as resin or stainless steel. In the case of the resin bolt 51, the permanent magnet 48 is integrally molded in, for example, the resin bolt 51. When the bolt 51 is made of a non-magnetic metal material such as stainless steel, for example, a recess (not shown) is formed on the head surface of the bolt 51, a permanent magnet 48 is provided in the recess, and the bolt 51 is provided with an adhesive or the like. By covering the recessed portion, the permanent magnet 48 is embedded in the head. Therefore, the position sensor 44 detects the advance / retreat position of the output rod 25a by reading the change in the magnetic field of the permanent magnet 48 accompanying the advance / retreat of the output rod 25a by each of the semiconductor elements 45. The permanent magnet 48 may be embedded directly in the detent component 43 by omitting the bolt.

<Other mechanical configurations>
As shown in FIG. 2, the case 6b is integrally formed with the unit support member main body 3A as a part of the unit support member 3. The case 6b is formed in a bottomed tubular shape, and is provided with a motor accommodating portion that supports the motor 26 and a linear motion mechanism accommodating 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 accommodating portion. 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 output rod 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 coupling portion 6d which is the 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. 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.

<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 actuator main body 7. .. This rotation is added to the steering by the driver's steering wheel operation, that is, is added to the rotation of the knuckle 6 around the kingpin axis by the steering device 11, and is performed as auxiliary steering, and one wheel can be independently steered. .. By making the auxiliary steering angles of the left and right wheels 9 and 9 different, the toe angle between the left and right wheels 9 and 9 can be arbitrarily changed.

Therefore, the hub unit 1 with a steering function may be used for either steering wheels such as front wheels or non-steering wheels such as rear wheels. When used for the steering wheel, by installing it on a member whose direction is changed by the steering device 11, the left and right wheels are individually or interlocked with the left and right wheels 9 in addition to steering by the driver's steering wheel operation. It becomes a mechanism to make a slight angle change of. Regarding the auxiliary steering angle, a slight angle is sufficient for improving the vehicle's kinetic performance and driving stability / safety, and even if the auxiliary steering angle is ± 5 degrees or less, it is sufficient. The angle of auxiliary steering is controlled by the steering actuator 5.

In addition, the difference in steering angle between the left and right wheels can be changed according to the traveling speed during turning. 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 wheel angle can be arbitrarily changed during traveling in this way, it is possible to improve the kinetic performance of the vehicle and to travel stably and safely. By appropriately changing the steering angles of the left and right steering wheels during turning, the turning radius of the vehicle can be reduced and the turning performance can be improved.
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 running stability at high speeds without lowering running resistance at low speeds and deteriorating fuel efficiency.

When the hub unit 1 with steering function is applied to the non-steering wheels which are the rear wheels 9R, if the steering angle is set to the same phase as the front wheels 9F during turning, the yaw generated during steering is suppressed and the stability of the vehicle is improved. be able to. By adjusting the toe angle independently on the left and right even when traveling straight, driving stability can be ensured.

As the output rod 25a of the linear motion mechanism 25 moves forward and backward, the hub unit main body 2 is rotationally driven around the steering axis A to be steered. At this time, by sensing the movement amount of the output rod 25a by the position sensor 44, the wheels 9 are not affected by the play of the linear motion mechanism 25 itself and in the path of transmitting the driving force from the motor 26 to the linear motion mechanism 25. It is possible to properly and accurately manage the angle of the above, or to confirm whether the linear motion mechanism 25 is operating according to the command value. Further, since the measurement target Tg for the position sensor is provided in the detent component 43 for detenting the output rod 25a, the space can be reduced as compared with installing the measurement target Tg for the position sensor separately in the dedicated component. It is possible to reduce the size of the entire hub unit.

When the position sensor 44 is a magnetic sensor, it does not require a light source or the like, the configuration is simple, and it is excellent in durability in an environment subject to vibration during traveling. In this case, since the measurement target Tg for the position sensor is the permanent magnet 48, the magnetic sensor can read the change in the magnetic field of the permanent magnet 48 and accurately detect the movement amount of the output rod 25a.

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

<Application to non-steering wheels>
The hub unit 1 with a steering function may be used for non-steering wheels. For example, as shown in FIG. 11, in a vehicle with front wheel steering, the suspension frame component 6R serving as a wheel bearing installation portion of the suspension device 12R supporting the rear wheel 9R may be set and used for rear wheel steering. In the hub unit 1 with a steering function of the non-steering wheels, depending on the demand of vehicle control, not only the above-mentioned minute steering angle but also a relatively large angle such as 10 ° to 20 ° may be taken individually for the left and right wheels.
Others As shown in FIG. 12, the hub unit 1 with a steering function may be used for the left and right front wheels 9F and 9F which are steering wheels and the left and right rear wheels 9R and 9R which are non-steering wheels, respectively.

<About the steering system>
As shown in FIG. 2, this steering system includes a hub unit 1 with a steering function according to any one embodiment, and a control device 29 for controlling a steering actuator 5 of the hub unit 1 with a steering function. The control device 29 has a steering control unit 30 and an actuator drive control unit 31. The steering control unit 30 outputs a current command signal corresponding to the auxiliary steering angle command signal (command signal) given by the upper control unit 32. At this time, the steering control unit 30 can appropriately and accurately manage the angle of the wheel 9 by performing feedback control from the position sensor 44 using the position sensor output which is the advance / retreat position information of the output rod 25a.

The upper control unit 32 is a higher control means of the steering control unit 30, and as the upper control unit 32, for example, an electric control unit (Vehicle Control Unit, abbreviated as VCU) that controls the entire vehicle is applied. The actuator drive control unit 31 drives and controls the steering actuator 5 by outputting a current corresponding to the current command signal input from the steering control unit 30. The actuator drive control unit 31 controls the electric power supplied to the coil of the motor 26. The actuator drive control unit 31 constitutes, for example, a half-bridge circuit using a switch element (not shown), and performs PWM control for determining the motor applied voltage according to the ON-OFF duty ratio of the switch element. As a result, the wheel can be slightly changed in angle in addition to 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.

The steering system may operate the steering actuators 5 and 5 by commands of an automatic driving device, a driving support device, etc. (not shown) instead of operating the steering wheel of the driver.
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.

1 ... Hub unit with steering function, 3 ... Unit support member, 5 ... Steering actuator, 6 ... Knuckle (undercarriage frame parts), 9 ... Wheels, 9F ... Front wheels, 9R ... Rear wheels, 15 ... Hub bearings, 25 ... Linear mechanism, 25a ... Output rod, 25aa ... Male screw part, 26 ... Motor (rotation drive source), 29 ... Control device, 30 ... Steering control unit, 31 ... Actuator drive control unit, 32 ... Upper control unit, 34 ... Actuator Case (fixed part), 35 ... nut part, 35a ... female thread part, 43 ... anti-rotation part, 44 ... position sensor, 48 ... permanent magnet

Claims (5)

A hub unit body with hub bearings that support the wheels,
A unit support member provided on the suspension frame component of the suspension device and rotatably supporting the hub unit body around the steering axis extending in the vertical direction.
A steering actuator for rotationally driving the hub unit body around the center of the steering axis is provided.
The steering actuator has a rotary drive source and a linear motion mechanism that converts the rotary output of the rotary drive source into a linear motion of the output rod, and the hub unit main body is moved by moving the output rod forward and backward. A hub unit with a steering function that is rotationally driven around the center of the steering shaft.
In the linear motion mechanism, a detent component for detenting the output rod is attached to the output rod and slidably contacts a fixed portion of the linear motion mechanism, and the detent component is used for a position sensor. A hub unit with a steering function provided with a measurement target and a position sensor provided at the fixed portion for detecting the displacement of the measurement target for the position sensor, which is the amount of movement of the output rod. The hub unit with a steering function according to claim 1, wherein the position sensor is a magnetic sensor and the measurement target for the position sensor is a permanent magnet. In the hub unit with a steering function according to claim 1 or 2, the linear motion mechanism has a nut portion rotatably supported by the unit support member and a male screw portion that meshes with a female screw portion of the nut portion. A hub unit with a steering function having the output rod provided in. The hub unit with a steering function according to any one of claims 1 to 3 and a control device are provided, and the control device receives a command signal of a host control unit and a position sensor output from the position sensor. It has a steering control unit that outputs a current command signal to the motor serving as the rotation drive source, and an actuator drive control unit that outputs a current corresponding to the current command signal and applies the current to the motor to drive the steering actuator. Steering 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 any one of claims 1 to 3.

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