JP7245077B2 - HUB UNIT WITH STEERING FUNCTION AND VEHICLE INCLUDING THE SAME - Google Patents

Description

The present invention relates to a hub unit with a steering function and a vehicle equipped with the same. By controlling the steering angle of the left and right wheels appropriately according to the driving conditions, it aims to improve fuel consumption, stability of driving performance, and safety. Regarding technology.

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

The Ackermann geometry is designed so that the steering angle difference between the left and right wheels is adjusted so that each wheel turns around a common point in order to turn the vehicle smoothly 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 for the wheels to generate cornering force in a direction that balances the centrifugal force, so the parallel geometry is preferable to the Ackermann geometry.

As mentioned above, a typical vehicle steering system is mechanically connected to the wheels, so it is generally possible to have only a single fixed steering geometry, which is intermediate between the Ackermann geometry and the parallel geometry. It is often set to a typical geometry. However, in this case, the steering angle difference between the left and right wheels is insufficient in the low speed range, resulting in an excessive steering angle of the outer wheels, and an excessive steering angle of the inner wheels in the high speed range. Unnecessary imbalance in the wheel lateral force distribution between the inner and outer wheels causes deterioration of fuel efficiency and premature wear of tires due to worsening of running resistance. There is the issue of damage.

Therefore, the applicant of the present application has proposed a hub unit with a steering function (Patent Document 3), in which, in addition to the steering by the steering wheel operation of the driver, it is possible to perform supplementary steering of individual wheels according to the driving situation.

DE 102012206337 A1 JP 2014-061744 A JP 2019-006226 A

In Patent Document 1, since two motors are used, the increase in the number of motors not only causes an increase in cost but also complicates control.
In Patent Document 2, since the hub bearing is cantilevered with respect to the steering shaft, the rigidity is lowered, and there is a possibility that the steering geometry may change due to the generation of excessive traveling G.
In addition, when a speed reducer is provided on the steering shaft, the size including the motor becomes large. As the size of the motor and the like increases, it becomes difficult to arrange the whole on the inner peripheral portion of the wheel. Moreover, when a reduction gear with a large reduction ratio is provided, the responsiveness deteriorates.

As described above, conventional mechanisms with an auxiliary steering function are intended to arbitrarily change the toe angle or camber angle of the wheels of a vehicle, and therefore require multiple motors and speed reduction mechanisms, resulting in 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, which increases the weight.
Also, if the kingpin axis and the steering axis of the mechanism with the auxiliary steering function are aligned, the component parts are arranged behind the hub unit (on the vehicle body side), making the whole size larger and heavier. .

A hub unit with a steering function has a motor and a linear motion mechanism that converts the rotational output of the motor into linear motion of an output rod. is rotationally driven (Patent Document 3).
The accuracy of the linear motion mechanism is ensured by inputting its position information to the control unit and performing feedback control. Although it is possible to use the rotation angle sensor output of the motor as the position information, there is an error in the actual movement of the linear motion mechanism due to backlash and elastic deformation of the trapezoidal screw of the linear motion mechanism. If a sensor for directly measuring the actual movement of the linear motion mechanism is provided separately, a space is required, which increases the size of the hub unit as a whole and may interfere with other parts such as the suspension.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hub unit with a steering function and a vehicle equipped with the hub unit, which can reduce the overall size of the hub unit and can accurately monitor the amount of movement of the output rod of the linear motion mechanism. .

A hub unit with a steering function of the present invention comprises a hub unit body having a hub bearing for supporting a wheel;
a unit support member provided on a suspension frame part of a suspension system for supporting the hub unit body rotatably around a steering shaft extending in the vertical direction;
a steering actuator that rotationally drives the hub unit body about the turning axis;
The steering actuator has a rotary drive source and a linear motion mechanism that converts the rotary output of the rotary drive source into linear motion of an output rod. A hub unit with a steering function that is rotationally driven around a steering axis,
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 as a position sensor. A measurement target is provided, and a position sensor for detecting displacement of the position sensor measurement target, which is the amount of movement of the output rod, is provided on the fixed portion.

According to this configuration, the hub unit main body is steered by being rotationally driven about the turning axis by advancing and retreating the output rod of the linear motion mechanism. At this time, by sensing the amount of movement of the output rod with a position sensor, the angle of the wheel can be appropriately adjusted in the path of transmitting the driving force from the rotary drive source to the linear motion mechanism and without being affected by play in the linear motion mechanism itself. It is possible to manage the system easily and accurately, or to check whether the linear motion mechanism is operating according to the command value. In addition, since the position sensor measurement target is provided on the rotation stop part that stops the rotation of the output rod, it is possible to reduce the space compared to installing the position sensor measurement target separately on the dedicated part, 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. In the case of the magnetic sensor, a light source or the like is unnecessary, the structure is simple, and the durability is excellent in an environment where the vehicle is subjected to vibrations during running. Further, since the measurement target for the position sensor is a permanent magnet, the magnetic sensor can read changes in the magnetic field of the permanent magnet and accurately detect the amount of movement of the output rod.

The direct-acting mechanism may have a nut portion rotatably supported by the unit support member, and the output rod provided on its outer periphery with a male thread portion that meshes with a female thread portion of the nut portion. In this case, the rotation-stopped output rod can be freely advanced and retracted by rotating the nut portion.

A steering system according to the present invention includes a hub unit with a steering function having any of the above configurations according to the present invention, and a control device, wherein the control device receives a command signal from a host controller and a position sensor output from the position sensor. A steering control unit receives the current and outputs a current command signal to the motor serving as the rotation drive source, and 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 steering function of the present invention can be controlled with a simple configuration, and the above advantages of the hub unit with 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 using the hub unit with steering function having any of the above configurations of the present invention.
Therefore, each of the effects described above can be obtained for the hub unit with steering function of the present invention. The front wheels are generally steered wheels, and if the hub unit with steering function of the present invention is applied to the steered wheels, it is effective in adjusting the toe angle during running. In addition, although the rear wheels are generally non-steered wheels, when applied to the non-steered wheels, the minimum turning radius can be reduced during low-speed running by slightly steering the non-steered wheels.

A hub unit with a steering function according to the present invention includes a hub unit body having a hub bearing for supporting a wheel, and a suspension frame component of a suspension system, and the hub unit body rotates around a steering shaft extending in the vertical direction. and a steering actuator for rotating the hub unit main body around the turning axis, wherein the steering actuator includes a rotational drive source and a rotational output of the rotational drive source. into a linear motion of an output rod, and the hub unit main body is rotationally driven about the steering axis by advancing and retracting the output rod. In the linear motion mechanism, a detent component for detenting the output rod is attached to the output rod, slidably contacts a fixed portion of the linear motion mechanism, and is positioned on the detent component. A sensor measurement target is provided, and a position sensor for detecting displacement of the position sensor measurement target, which is the amount of movement of the output rod, is provided on the fixed portion. Therefore, it is possible to reduce the size of the hub unit as a whole and to accurately monitor the amount of movement of the output rod of the linear motion mechanism.

A steering system according to the present invention includes a hub unit with a steering function having any of the above configurations according to the present invention, and a control device, wherein the control device receives a command signal from a host controller and a position sensor output from the position sensor. A steering control unit that receives a current and outputs a current command signal to the motor serving as the rotation drive source, and a current corresponding to the current command signal that is applied to the motor to drive the steering actuator. can be miniaturized, and the amount of movement of the output rod of the linear motion mechanism can be accurately monitored.

In the vehicle of the present invention, one or both of the front wheels and the rear wheels are supported using the hub unit with steering function of any of the above configurations of the present invention. The amount of movement of the output rod of the motion mechanism can be accurately monitored.

1 is a vertical cross-sectional view showing the structure of a hub unit with a steering function and its surroundings according to a first embodiment of the present invention; FIG. FIG. 3 is a horizontal cross-sectional view showing the structure of the hub unit with steering function and its surroundings; It is a perspective view which shows the external appearance of the hub unit with a steering function. It is a perspective view which shows the external appearance of the hub unit with a steering function. It is a side view of the hub unit with a steering function. It is a top view of the same hub unit with a steering function. FIG. 5 is a sectional view taken along line VI-VI of FIG. 4; FIG. 11 is a side view partially showing a detent component for an output rod of the hub unit with a steering function; FIG. 3 is an enlarged cross-sectional view showing an enlarged part of FIG. 2; FIG. 4 is an explanatory diagram of a conceptual configuration of a position sensor used in the hub unit with a steering function; FIG. 2 is a schematic plan view of an example of a vehicle provided with the hub unit with steering function; FIG. 10 is a schematic plan view of another example of a vehicle provided with any hub unit with steering function; FIG. 10 is a schematic plan view of another example of a vehicle provided with any hub unit with steering function;

[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. FIG.
<Schematic structure of hub unit with steering function>
As shown in FIG. 1 , the hub unit 1 with steering function includes a hub unit body 2 , a unit support member 3 , a rotation-allowing support member 4 and a steering actuator 5 . A unit support member 3 is provided integrally with a knuckle 6, which is an underbody frame component. The actuator main body 7 of the steering actuator 5 is provided on the inboard side of the unit support member 3 , and the hub unit main body 2 is provided on the outboard side of the unit support member 3 . When the hub unit 1 with a steering function is mounted on the vehicle, the vehicle width direction outer side of the vehicle is called the outboard side, and the vehicle width direction central side of the vehicle is called the inboard side. Note that the hub unit 1 with a steering function may be simply referred to as the hub unit 1 in some cases.

As shown in FIGS. 2 and 3 , the hub unit body 2 and the actuator body 7 are connected by a joint portion 8 . Normally, this joint portion 8 is attached with a boot (not shown) for waterproofing and dustproofing.

As shown in FIG. 1, the hub unit main body 2 is supported by a unit support member 3 via rotation-permitting support parts 4, 4 at two upper and lower positions so as to be rotatable about a steering axis A extending in the vertical direction. It is The steering axis A is different from the rotation axis O of the wheel 9, and is also different from the kingpin axis for main steering. In a normal vehicle, the kingpin angle is set at 10 to 20 degrees for the purpose of improving the straight running stability of the vehicle. It has a steering shaft of (axis). The wheel 9 includes a wheel 9a and a tire 9b.

<Location of hub unit 1 with steering function>
In this embodiment, the steering function-equipped hub unit 1 is used to steer the steered wheels, specifically, the front wheels 9F of the vehicle 10 as shown in FIG. ±5 degrees) is provided integrally with the knuckle 6 of the suspension system 12 . However, in the hub unit 1 with a steering function for the steered wheels, depending on the vehicle control requirements, not only the small angle but also relatively large angles such as 10° to 20° may be adopted separately for the left and right wheels. The same applies to a 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 a driver's operation of a steering wheel 11a or by commands from an automatic driving device or a driving support device (not shown). 14 is connected to a steering coupling portion 6d (described later) of the unit support member 3. As shown in FIG. The steering device 11 is of a rack and pinion type or the like, but any type of steering device may be used. The suspension system 12 employs, for example, a strut suspension mechanism that directly fixes the shock absorber to the knuckle 6, but a double wishbone suspension mechanism, a multi-link suspension mechanism, or other suspension mechanisms may also be applied. .

<Regarding the 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) as 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 rolling elements 20 such as balls interposed between the inner and outer rings 18, 19. 1) It serves as a link between

In the illustrated example, the hub bearing 15 is an angular contact 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 double rows. The inner ring 18 has a hub ring portion 18a having a hub flange 18aa and forming an outboard side raceway surface, and an inner ring portion 18b forming an inboard side raceway surface. 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 16a fitted to the outer peripheral surface of the outer ring 19, and a trunnion shaft-shaped steered shaft provided vertically projecting from the outer periphery of the annular portion 16a. It has parts 16b, 16b. The steered shaft portions 16b, which are upper and lower mounting shaft portions, are provided coaxially with the steered shaft center A. As shown in FIG.

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 two upper and lower brake caliper attachment portions 22 (FIG. 4) formed integrally with the outer ring 19 so as to protrude in the form of arms.

<Regarding rotation-permitting support parts and unit support members>
As shown in FIG. 6, each rotation-permitting support component 4 consists of a rolling bearing. In this example, tapered roller bearings are used as rolling bearings. The rolling bearing has an inner ring 4a fitted to the outer circumference 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 combined body 3B. A substantially ring-shaped unit support member assembly 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 in the upper and lower portions of the inboard-side side surface of the unit support member combined body 3B.

As shown in FIGS. 5 and 6, the upper and lower portions of the outboard side end of the unit support member main body 3A are formed with partially concave spherical fitting hole forming portions 3Aa, respectively. A unit support member assembly 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 in each of the upper and lower portions, thereby forming a fitting hole extending all around. It is formed. The outer ring 4b is fitted into this fitting hole. In addition, in FIG. 3, the unit support member 3 is represented by a dashed line.

As shown in FIG. 6, each steering shaft portion 16b is formed as a hollow shaft and has a female thread portion extending radially in an inner peripheral hole. there is A disk-shaped pressing member 24 is interposed on the end surface of the inner ring 4a, and a bolt 23 screwed into the female thread portion applies a pressing force to the end surface of the inner ring 4a, thereby preloading each rotation-allowing support member 4. giving. That is, the initial preload is set so that the preload is not lost even when an external force such as the weight of the vehicle acts on the hub unit. Thereby, the rigidity of each rotation-permitting support component 4 can be increased. The rolling bearing of the rotation-permitting support component 4 may be an angular ball bearing or a four-point contact ball bearing instead of the tapered roller bearing. Also in that case, preload can be applied in the same manner as described above.

As shown in FIG. 1, the upper and lower steered shafts 16b, 16b are supported by the unit support member 3 via rotation-permitting support parts 4, 4, respectively, and each rotation-permitting support part 4 is inside the wheel 9a of the wheel 9. Located in In this example, each rotation-permitting 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 that acts as a point of action for applying an auxiliary steering force to the outer ring 19 of the hub bearing 15, and integrally protrudes from the outer ring 16 or part of the outer circumference of the outer ring 19. . The arm portion 17 is rotatably connected to an output rod 25 a serving as a direct-acting output portion of the steering actuator 5 via a joint portion 8 . As a result, the output rod 25a of the steering actuator 5 advances and retreats (straight motion), so that the hub unit main body 2 rotates about the steering axis A, that is, assists steering.

<Steering actuator 5>
As shown in FIG. 3, the steering actuator 5 has an actuator body 7 that rotates the hub unit body 2 around the turning axis A (FIG. 1).
As shown in FIG. 2, the actuator body 7 includes a motor 26 as a rotational drive source, a speed reducer 27 that reduces the rotation of the motor 26, and forward and reverse rotational output of the speed reducer 27 as a reciprocating straight line of an output rod 25a. and a linear motion mechanism 25 that converts 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>
The speed reducer 27 can use a winding type transmission mechanism such as a belt transmission mechanism, a gear train, or the like, and the belt transmission mechanism is used in the example of FIG. The speed reducer 27 has a drive pulley 27a, a driven pulley 27b, and a belt 27c. A drive pulley 27 a is coupled to the motor shaft of the motor 26 , and a driven pulley 27 b is provided to 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. As shown in FIG.

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

The feed screw mechanism 33 has a nut portion 35 , the output rod 25 a as a screw shaft, and a sliding bearing 37 . The output rod 25a is prevented from rotating with respect to the unit support member 3 by a rotation preventing member 43, which will be described later. The nut portion 35 is provided with a driven pulley 27b at an axially intermediate portion of the outer peripheral portion, and is rotatably supported by the unit support member 3 by rotation support bearings 28, 28 on both sides in the axial direction. A female screw portion 35a is provided on the inner periphery of the nut portion 35 . A male threaded portion 25aa that meshes with the female threaded portion 35a of the nut portion 35 is provided on the outer periphery of the output rod 25a.

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

As the rotation support bearing 28, in this example, two tapered roller bearings are combined face-to-face via a driven pulley 27b. These rotation support bearings 28, 28 may be arranged back to back or face to face, but front to face arrangement is preferable from the standpoint of ease of assembly and preload adjustment using shims or the like.

Each rotation support bearing 28 includes an outer ring 28a which is a fixed ring, an inner ring 28b which is a rotating ring, a plurality of rolling elements 28c interposed between the inner and outer rings 28b and 28a, and a retainer 28d that holds the rolling elements 28c. have Each inner ring 28b is fitted and fixed to the outer peripheral surface of the nut portion 35, and is restricted in the axial direction by retaining rings 39,39. The outer ring 28a of the outboard-side rotation support bearing 28 is fitted and fixed in the fitting hole of the case 6b, and the outer ring 28a of the inboard-side rotation support bearing 28 is fitted to the inner peripheral surface of the actuator case 34 on the outboard side. It is mated and fixed. Note that the rotation support bearing 28 may be an angular ball bearing. Also in this case, the arrangement of the rotation support bearings 28, 28 may be either back-to-back or face-to-face.

As shown in FIGS. 7 and 8, the anti-rotation component 43 is a shaft-like member provided at the inboard end, which is the rear end of the output rod 25a. The anti-rotation member 43 is fitted and fixed to the output rod 25a in a penetrating manner at the inboard end of the output rod 25a so as to extend in the vertical direction and in the direction orthogonal to the axial direction of the output rod 25a. . Annular sliding bearings 49 a and 49 b are fitted to both ends in the axial direction of the outer periphery of the anti-rotation component 43 .

A flat surface (so-called D-cut surface) 50 parallel to one end surface of the lower sliding bearing 49b is formed in a portion of the inboard side end of the output rod 25a that faces the lower sliding bearing 49b. One end face of the sliding bearing 49b is brought into contact with the flat surface 50 of the output rod 25a, and a bolt 51 is screwed into the anti-rotation component 43 to press the other end face of the lower sliding bearing 49b. As a result, the vertical positions of the anti-rotation component 43 , the bolt 51 and the slide bearings 49 a and 49 b are regulated to desired positions with respect to the actuator case 34 . A position sensor measurement target Tg, 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, respectively, is formed in the actuator case 34. As shown in FIG. In other words, the anti-rotation component 43 slidably contacts the guide surfaces 52a, 52b of the actuator case 34, which is the fixed portion of the linear motion mechanism 25, via the sliding bearings 49a, 49b. Therefore, by sliding the detent part 43 along the guide groove 52 of the actuator case 34 via the sliding bearings 49a and 49b, the output rod 25a can be reciprocated in the axial direction. Further, at least the guide surfaces 52a and 52b are subjected to, for example, wear prevention treatment so that the detent member 43 slides through the sliding bearings 49a and 49b. The sliding bearings 49a and 49b can be made of metal such as copper alloy or porous sintered alloy, or can be made of resin such as fluororesin.

As shown in FIG. 2, the linear motion mechanism 25 is provided with a feed screw mechanism using the sliding screw of the trapezoidal screw, so that the reverse input from the tire 9b can be prevented more effectively. 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 is also possible in which the driving force of the motor 26 is directly transmitted to the direct acting mechanism 25 without passing through a speed reducer.

<Regarding position sensors, etc.>
As shown in FIGS. 7 and 8, the steering actuator 5 includes a position sensor 44, which monitors the amount of axial movement of the output rod 25a. This position sensor 44 is provided in the actuator case 34 which is a fixed portion of the linear motion mechanism 25 . A position sensor 44 is fixed to a substrate 53 fixed in the actuator case 34, and the position sensor 44 faces a path along which a position sensor measurement target Tg, which will be described later, advances and retreats. Further, when the output rod 25a is at a predetermined axial position (advance/retreat position), the position sensor 44 and the position sensor measurement target Tg face each other across a predetermined gap Gp. The defined axial position and the defined gap Gp are axial positions and gaps that are arbitrarily determined by design or the like, and are suitable axial positions, for example, based on either one or both of tests and simulations. , is determined by finding the gap.

As conceptually shown in FIG. 9, the position sensor 44 has two semiconductor elements 45 for detecting changes in position in one package 46, and outputs the output of each semiconductor element 45 to the outside of the package 46. It has separate output terminals 47, 47 for The position sensor 44 can use various sensors such as a magnetic type, an optical type, and an electrostatic capacity type. ing.

As shown in FIG. 8, the anti-rotation component 43 is provided with a permanent magnet 48 that serves as the position sensor measurement target Tg. Specifically, a permanent magnet 48 is embedded in the head of a bolt 51 screwed to the axial end of the anti-rotation component 43 . Also, the bolt 51 is made of a non-magnetic material such as resin or stainless steel. In the case of the bolt 51 made of resin, the permanent magnet 48 is integrally formed inside the bolt 51 made of resin, for example. When the bolt 51 is made of a non-magnetic metal material such as stainless steel, for example, a recess (not shown) is formed in the head surface of the bolt 51, the permanent magnet 48 is provided in this recess, and the above-described magnet is attached with an adhesive or the like. A permanent magnet 48 is embedded in the head by covering the recess. Accordingly, the position sensor 44 detects the forward/backward position of the output rod 25a by reading the change in the magnetic field of the permanent magnet 48 accompanying the forward/backward movement of the output rod 25a. It should be noted that the permanent magnet 48 may be embedded directly in the anti-rotation 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 part of the unit support member 3. As shown in FIG. The case 6b is formed in a cylindrical shape with a bottom, 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 inside the case is formed in the motor accommodating portion. A fitting hole for supporting the linear motion mechanism 25 at a predetermined position in the case, a through hole for allowing the forward/backward movement of the output rod 25a, and the like are formed in the linear motion mechanism accommodating portion.

As shown in FIG. 3, the unit support member main body 3A includes the case 6b, a shock absorber mounting portion 6c that serves as a shock absorber mounting portion, and a steering device connecting portion 6d that serves as a connecting portion for the steering device 11 (FIG. 2). have. The shock absorber attachment portion 6c and the steering device coupling portion 6d are also formed integrally with the unit support member main body 3A. A shock absorber attachment 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 protrude from the side portion of the outer surface portion of the unit support member main body 3A.

<Effect>
According to the steering function-equipped hub unit 1 described above, the hub unit body 2 including the hub bearings 15 that support the wheels 9 can be freely rotated around the turning axis A by driving the actuator body 7 . . This rotation is added to the steering by the steering wheel operation of the driver, that is, to the rotation of the knuckle 6 about the kingpin axis by the steering device 11, and is performed as an auxiliary steering, and independent steering of one wheel can be performed. . The toe angle between the left and right wheels 9, 9 can be arbitrarily changed by making the angles of the auxiliary steering of the left and right wheels 9, 9 different.

Therefore, the hub unit 1 with a steering function may be used for both steered wheels such as the front wheels and non-steered wheels such as the rear wheels. When used as a steered wheel, by being installed on a member whose direction can be changed by the steering device 11, in addition to the steering by the driver's steering operation, the left and right wheels are independent or interlocked with the left and right wheels. It is a mechanism that makes a minute change in the angle of As for the angle of the auxiliary steering, a slight angle is sufficient to improve the motion performance of the vehicle and to improve the stability and safety of the vehicle. The angle of the auxiliary steering is controlled by the steering actuator 5 .

Also, during turning, the steering angle difference between the left and right wheels can be changed according to the running speed. For example, it is possible to change the steering geometry while driving, such as parallel geometry for high-speed cornering and Ackermann geometry for low-speed cornering. Since the wheel angle can be arbitrarily changed during running in this manner, the motion performance of the vehicle can be improved, and the vehicle can run stably and safely. By appropriately changing the steering angle of the left and right steered wheels during cornering, it is possible to reduce the turning radius of the vehicle and improve the tight turning performance.
Furthermore, even when driving in a straight line, by adjusting the amount of toe angle according to each situation, it is possible to make adjustments such as lowering running resistance at low speeds without deteriorating fuel efficiency and ensuring running stability at high speeds.

When the hub unit 1 with steering function is applied to the rear wheels 9R, which are the non-steered wheels, when 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 enhanced. be able to. Driving stability can be ensured by adjusting the left and right toe angles independently even when driving in a straight line.

As the output rod 25a of the linear motion mechanism 25 advances and retreats, the hub unit main body 2 is rotatably driven around the turning axis A and steered. At this time, by sensing the amount of movement of the output rod 25a by the position sensor 44, the wheels 9 are moved in the path of transmitting the driving force from the motor 26 to the linear motion mechanism 25 and without being affected by the play of the linear motion mechanism 25 itself. angle can be managed appropriately and accurately, or whether the linear motion mechanism 25 is operating according to the command value can be confirmed. In addition, since the position sensor measurement target Tg is provided on the rotation prevention component 43 that prevents rotation of the output rod 25a, the space can be reduced compared to installing the position sensor measurement target Tg separately on a dedicated component. It is possible to reduce the size of the entire hub unit.

If the position sensor 44 is a magnetic sensor, a light source or the like is not required, which simplifies the configuration and provides excellent durability in an environment where the vehicle is subject to vibrations during travel. In this case, since the position sensor measurement target Tg 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 amount of movement of the output rod 25a.

<About other embodiments>
In the following description, the same reference numerals are given to the parts corresponding to the items previously described in each embodiment, and duplicate descriptions are omitted. When only a portion of the configuration is described, the other portions of the configuration are the same as those previously described unless otherwise specified. The same configuration has the same effect. It is possible not only to combine the parts specifically described in each embodiment, but also to partially combine the embodiments if there is no particular problem with the combination.

<About application to non-steering wheels>
The hub unit 1 with steering function may be used for non-steering wheels. For example, as shown in FIG. 11, in a vehicle with front-wheel steering, it may be set in an underbody frame component 6R serving as a wheel bearing installation portion of a suspension device 12R that supports a rear wheel 9R, and used for rear-wheel steering. In the hub unit 1 with a steering function for the non-steerable wheels, depending on the vehicle control requirements, a relatively large steering angle such as 10° to 20°, for example, may be adopted for each of the left and right wheels in addition to the small steering angle described above.
Alternatively, as shown in FIG. 12, the hub unit 1 with steering function may be used for left and right front wheels 9F, 9F as steered wheels and left and right rear wheels 9R, 9R as non-steered wheels.

<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 of the embodiments, and a control device 29 that controls the steering actuator 5 of the hub unit 1 with a steering function. The control device 29 has a steering control section 30 and an actuator drive control section 31 . The steering control section 30 outputs a current command signal according to the auxiliary steering angle command signal (command signal) given from the host control section 32 . At this time, the steering control unit 30 performs feedback control using the position sensor output, which is forward/backward position information of the output rod 25a, from the position sensor 44, so that the angle of the wheel 9 can be managed appropriately and accurately.

The host controller 32 is a host controller of the steering controller 30. As the host controller 32, for example, a vehicle control unit (VCU) for controlling the entire vehicle is applied. The actuator drive control section 31 drives and controls the steering actuator 5 by outputting a current corresponding to the current command signal input from the steering control section 30 . The actuator drive control section 31 controls power supplied to the coils of the motor 26 . The actuator drive control unit 31, for example, constitutes a half-bridge circuit using switch elements (not shown), and performs PWM control for determining the voltage applied to the motor according to the ON-OFF duty ratio of the switch elements. As a result, the angle of the wheels can be slightly changed in addition to the steering by the steering wheel operation of the driver. Even when driving 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, 5 according to a command from an automatic driving device or a driving support device (not shown) instead of the steering wheel operation by the driver.
As mentioned above, although the form for implementing this invention was demonstrated based on embodiment, embodiment disclosed this time is an illustration and is not restrictive at all points. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

DESCRIPTION OF SYMBOLS 1... Hub unit with a steering function, 3... Unit support member, 5... Actuator for steering, 6... Knuckle (undercarriage frame part), 9... Wheel, 9F... Front wheel, 9R... Rear wheel, 15... Hub bearing, 25... Linear motion mechanism 25a Output rod 25aa Male threaded portion 26 Motor (rotary drive source) 29 Control device 30 Steering control unit 31 Actuator drive control unit 32 Host control unit 34 Actuator Case (fixed portion) 35 Nut portion 35a Female screw portion 43 Anti-rotation component 44 Position sensor 48 Permanent magnet

Claims (5)

a hub unit main body having a hub bearing that supports a wheel and a trunnion shaft-shaped steered shaft portion that protrudes vertically from the outer periphery of the hub bearing ;
a unit support member provided on a suspension frame part of a suspension system and supporting the hub unit main body so as to be rotatable around the axis of the upper and lower steering shaft portions ;
a steering actuator that rotationally drives the hub unit body about the turning axis;
The steering actuator has a rotary drive source and a linear motion mechanism that converts the rotary output of the rotary drive source into linear motion of an output rod. A hub unit with a steering function that is rotationally driven around a steering axis,
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 as a position sensor. A measurement target is provided, and a position sensor for detecting displacement of the position sensor measurement target, which is the amount of movement of the output rod, is provided in the fixed portion , and the anti-rotation component is attached to the fixed portion via a slide bearing. A hub unit with a steering function that slidably contacts the guide surface of the part . 2. The hub unit with steering function according to claim 1, wherein said position sensor is a magnetic sensor and said measurement target for said position sensor is a permanent magnet. 3. The hub unit with a steering function according to claim 1, wherein the linear motion mechanism comprises a nut portion rotatably supported by the unit support member, and a male thread portion meshing with the female thread portion of the nut portion. and the output rod provided in the hub unit with a steering function. A hub unit with a steering function according to any one of claims 1 to 3, and a controller, wherein the controller receives a command signal from a host controller and a position sensor output from the position sensor. , a steering control section for outputting a current command signal to the motor serving as the rotation drive source, and an actuator drive control section for outputting a current corresponding to the current command signal and applying it to the motor to drive the steering actuator. steering system. A vehicle in which one or both of front wheels and rear wheels are supported using the hub unit with a steering function according to any one of claims 1 to 3.

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