JP7229751B2 - Hub unit with steering function, steering system, and vehicle equipped with the same - Google Patents

Description

The present invention relates to a hub unit with a steering function, a steering system, and a vehicle equipped with the same, which have a function of performing auxiliary steering independently of the left and right wheels in addition to steering by a steering device. to an appropriate turning angle, thereby improving fuel consumption, stabilizing running performance, and improving safety.

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.

DE 102012206337 A1 JP 2014-061744 A

Since the technique described in Patent Document 1 uses two motors, the increase in the number of motors not only causes an increase in cost, but also complicates control.
In the technique described in Patent Document 2, since the hub bearing is cantilevered with respect to the steered shaft, the rigidity is lowered, and there is a possibility that the steering geometry will 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 increases, it becomes difficult to arrange the whole on the inner periphery of the wheel. Moreover, when a reduction gear with a large reduction ratio is provided, the responsiveness deteriorates.

As described above, the conventional mechanism with an auxiliary steering function is intended to arbitrarily change the toe angle and camber angle of the wheels of the vehicle. It is configured. In addition, it is difficult to secure the rigidity, and in order to secure the rigidity, it is necessary to increase the size, which increases the weight.
Further, when the kingpin axis and the steered axis are aligned, the component parts are arranged behind the hub unit (on the vehicle body side), resulting in an increase in the overall size and weight.

In order to freely change the toe angle and camber angle of the wheels in a running vehicle, a complicated configuration is required, and there is a possibility that the number of component parts increases and the vehicle becomes large.
A mechanism with a steering function, such as a hub unit mechanism with a steering function, needs to be made smaller in order to fit in the limited space inside the wheel. growing.

In a hub unit with a steering function, it is necessary to appropriately monitor the amount of movement of the output rod of the linear motion mechanism using a trapezoidal screw or the like in order to precisely control the steering angle. If the position sensor is arranged outside the linear motion mechanism, the hub unit with a steering function becomes large and may interfere with other parts such as the suspension. It is also possible to calculate the amount of rotation of the nut portion of the linear motion mechanism using a rotation sensor such as a resolver provided in the motor, and calculate the amount of movement of the output rod of the linear motion mechanism from this value. It is difficult to obtain an accurate amount of movement due to play in the mechanism.
The incremental rotation sensor can detect the amount of movement, but cannot detect the absolute position when the power is turned on. An absolute type rotation sensor can detect an absolute position, but the size of the rotation sensor increases and the cost increases.

An object of the present invention is to provide a function to perform auxiliary steering independently of the left and right wheels in addition to steering by a normal steering device, and to control the left and right wheels to an appropriate turning angle according to the driving situation, thereby improving fuel efficiency. In addition, the compact structure that can be accommodated in the tire house allows accurate monitoring of the amount of movement of the output rod of the linear motion mechanism, enabling auxiliary steering. An object of the present invention is to provide a hub unit with a steering function that can be accurately controlled, a steering system, and a vehicle equipped with the same.

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 linear motion mechanism in which the output rod advances and retreats,
A position sensor for detecting the amount of movement or the forward/backward position of the output rod is arranged in the hollow portion of the output rod of the linear motion mechanism.

When this configuration is applied to the front wheels, which are the steered wheels, the wheels are steered together with the knuckles and the unit support by the steering wheel operation of the driver with a normal steering device. Auxiliary steering of a slight angle around the steering axis in the hub unit can be performed independently for each wheel.
When this configuration is applied to the rear wheels, which are non-steerable wheels, the hub unit with steering function does not steer as a whole. can be done independently.
By the steering actuator, the hub unit body having the hub bearing can be freely rotated within a certain range around the turning axis, and the toe angle of the wheels, for example, can be arbitrarily changed according to the driving conditions of the vehicle. be able to.
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 during running, such as parallel geometry for high-speed cornering and Ackermann geometry for low-speed cornering. Since the wheel angle can be freely changed while the vehicle is running in this manner, the motion performance of the vehicle can be improved, and the vehicle can run stably and safely. Furthermore, by appropriately changing the steering angle of the left and right wheels, it is possible to reduce the turning radius of the vehicle during cornering and improve the tight turning performance.

Furthermore, by adjusting the amount of toe angle according to each situation, even when driving in a straight line, the tire angle is toeed in at high speeds to improve driving stability without deteriorating fuel efficiency by directing the tires straight at low speeds and reducing resistance. It is possible to make adjustments such as ensuring
When applied to the rear wheels, if the steering angle is set to the same phase as the front wheels, the yaw that occurs during steering can be suppressed and the stability of the vehicle can be enhanced. Furthermore, by adjusting the toe angle independently on the left and right sides, it is possible to ensure running stability even when driving in a straight line.
In order to control the behavior of the vehicle in this way, it is necessary to accurately control the steering angle of the wheels. It is arranged in the hollow part of the output rod. By adopting the configuration in which the position sensor is arranged in the hollow portion of the output rod, the hub unit with steering function can be downsized and can be accommodated in the tire house. In addition, since deviation from Abbe's principle is reduced, the position measurement error is reduced.
This hub unit with a steering function is equipped with a function to perform auxiliary steering independently of the left and right wheels in addition to the steering by the normal steering device, and controls the left and right wheels to the appropriate steering angle according to the driving situation. By doing so, it is possible to improve fuel efficiency, stability of running performance, and safety, and it is possible to accurately monitor the amount of movement of the output rod of the linear motion mechanism with a compact structure that can be accommodated in the tire house. Auxiliary steering can be controlled with high accuracy.

In this invention, the position sensor may be a magnetic sensor.
A magnetic sensor does not require a light source, simplifies the configuration, and has excellent durability in an environment where the vehicle is subjected to vibrations during travel.

When used as a magnetic sensor, a magnet serving as a sensor target is fixed to the output rod, and the position sensor is fixed to the unit support member and relatively moves forward and backward in the hollow portion by the forward and backward movement of the output rod. It is good also as a structure attached to the sensor support member. This makes it possible to simply implement a configuration in which the position sensor is provided inside the output rod.

A steering system according to the present invention includes a hub unit with a steering function having any one of the above configurations according to the present invention, and a control device. and an actuator drive 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 the steering system of this construction, the hub unit with steering function of the present invention can be controlled with a simple construction, and the above advantages of the hub unit with steering function can be obtained effectively.

A first vehicle of the present invention includes the hub unit with steering function of any one of the above configurations of the present invention or the steering system of the present invention, and the hub units with steering function are provided on left and right front wheels.
According to the vehicle having this configuration, the above-described effects can be obtained when the hub unit with steering function of the present invention is installed on the front wheels.

Another vehicle of the present invention includes the hub unit with steering function of any one of the above configurations of the present invention or the steering system of the present invention, and the hub units with steering function are provided on left and right rear wheels.
According to the vehicle having this configuration, the above-described effects can be obtained when the hub unit with steering function of the present invention is efficiently installed.

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 about the steering axis, the steering actuator having a linear motion mechanism for advancing and retracting an output rod. Since a position sensor for detecting the amount of movement or the forward/backward position of the output rod is arranged in the hollow portion of the output rod of the linear motion mechanism, auxiliary steering is performed in addition to the steering by the normal steering device. Equipped with a function to operate the left and right wheels independently, and by controlling the steering angle of the left and right wheels according to the driving situation, it is possible to improve fuel efficiency, stability and safety of driving, and to fit inside the tire housing. With a compact structure, the amount of movement of the output rod of the linear motion mechanism can be accurately monitored, and the auxiliary steering can be controlled with high accuracy.

A steering system according to the present invention includes a hub unit with a steering function having any one of the above configurations according to the present invention, and a control device. and an actuator drive control unit that outputs a current corresponding to the current command signal and applies it to the motor to drive the steering actuator. By controlling the hub unit with a steering function with a simple configuration, the above advantages of the hub unit with a steering function of the present invention can be effectively obtained.

A vehicle according to the present invention includes a hub unit with a steering function having any one of the above configurations of the present invention or a steering system according to the present invention, and the hub units with a steering function are mounted on left and right front wheels or rear wheels. It is possible to obtain the above effects when the hub unit with steering function of the invention is mounted on the front wheels or the rear wheels.

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 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 the line VI-VI of FIG. 4; 4 is an enlarged cutaway side view of a steering actuator in the hub unit with steering function; FIG. FIG. 2 is a schematic plan view of an example of a vehicle provided with the hub unit with steering function; FIG. 11 is a schematic plan view of another example of a vehicle provided with the hub unit with steering function; FIG. 11 is a schematic plan view of another example of a vehicle provided with the hub unit with steering function;

[First Embodiment]
A hub unit with a steering function according to a first embodiment of the invention will be described with reference to FIGS. 1 to 8. FIG. <Schematic structure of hub unit with steering function>
As shown in FIG. 1, this hub unit 1 with a steering function includes a hub unit body 2 having a hub bearing 15, a unit support member 3, and a steering actuator 5. As shown in FIG. The unit support member 3 is provided integrally with the 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 rudder axis of (shaft). 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, in addition to steering by a steering device 11 that normally steers the steered wheels, specifically the front wheels 9F of a vehicle 10 as shown in FIG. It is provided integrally with the knuckle 6 of the suspension system 12 as a mechanism for steering a very small angle (approximately ±5 degrees).

As shown in FIG. 8, 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). It is connected to a steering coupling portion 6d (described later) of the unit support member 3 (see FIG. 2). 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-type suspension mechanism that directly fixes the shock absorber to the knuckle 6, but a multi-link suspension mechanism or other suspension mechanisms may 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 provided on the outer ring 16 as a steering force receiving portion for assist steering, which will be described later. and a portion 17 (FIG. 3).
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 includes a hub ring portion 18a that has a hub flange 18aa and forms an outboard side raceway surface, and an inner ring that is fitted and fixed to the outer periphery of the hub ring portion 18a to form an inboard side raceway surface. and a portion 18b. As shown in FIG. 1, the wheel 9a of the wheel 9 is fixed to the hub flange 18aa by the hub bolt 41 in a state of being overlapped with 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 of the hub bearing 15, and a steering center provided vertically protruding from the outer periphery of the annular portion 16a. trunnion shaft-shaped turning shaft portions 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. Each steered shaft portion 16b includes a tapered enlarged diameter portion 16bb whose base end increases in diameter toward the outer peripheral surface of the outer ring 19, and a fixed portion which is a tip side portion of the enlarged diameter portion 16bb. It is composed of a constant diameter portion 16ba having an outer diameter. The outer diameter side edge of the expanded diameter portion 16bb is formed so as to be integrally connected to the annular portion 16a.

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 16 of the hub unit body 2 so as to protrude in the form of arms.

<Regarding Rotation Allowable Supporting Part 4 and Unit Supporting Member 3>
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 includes an inner ring 4a fitted to the constant diameter portion 16ba on 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. and

The unit support member 3 has a unit support member main body 3A integral with the knuckle 6 and a unit support member combined body 3B. A substantially half-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 hatching with a dashed line.

As shown in FIG. 6, each mounting shaft portion 16b is formed as a hollow shaft with a female thread portion extending radially in an inner peripheral hole, and a bolt 23 screwed into the female thread portion is provided. . 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. As the rolling bearing of the rotation-allowing support component 4, it is possible to use other types of bearings such as angular contact ball bearings or four-point contact ball bearings instead of tapered roller bearings. is preferred.

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 of the hub unit main body 2 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 is integrated with a portion of the outer circumference of the outer ring 16. protrude. The arm portion 17 is rotatably connected to the direct-acting output portion 25 a of the steering actuator 5 via the joint portion 8 . As a result, the direct-acting output portion 25a of the steering actuator 5 advances and retreats, so that the hub unit main body 2 rotates about the turning axis A (FIG. 1), that is, is assisted to be steered.

<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 main body 7 includes a motor 26 as a drive source, a speed reducer 27 that reduces the rotation of the motor 26, and a direct-acting output section that outputs the forward and reverse rotation output of the speed reducer 27. and a linear motion mechanism 25 that converts the rod 25a into reciprocating linear motion. The motor 26 is, for example, a permanent magnet type synchronous motor, but may be a DC motor or an induction motor.

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 27a is coupled to the motor shaft of the motor 26, and the linear motion mechanism 25 is provided with a driven pulley 27b as described later. 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.

<Linear motion mechanism 25>
The linear motion mechanism 25 can use a feed screw mechanism such as a slide screw or a ball screw, or a rack and pinion mechanism, etc. In this example, a feed screw mechanism using a trapezoidal slide screw is used. Specifically, the linear motion mechanism 25 includes a nut member 25b, which is provided with the driven pulley 27b on the outer peripheral portion and is rotatably installed on the unit support member 3 by bearings 42, 42 on both sides in the axial direction, and the nut member 25b. It is composed of an output rod 25a, which is a direct-acting output portion, provided on the outer periphery with a male screw portion 25aa that meshes with the member 25b. The output rod 25a is prevented from rotating with respect to the unit support member 3 by a pin-shaped anti-rotation member 40 (see FIG. 7).
Since the direct-acting mechanism 25 includes a feed screw mechanism using the sliding 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 sub-assembly 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 using a speed reducer.

<Position sensor 44>
As shown enlarged in FIG. 6, the output rod 25a is a hollow shaft with a circular cross-sectional shape, and the rear portion of the inner diameter hole is a hollow portion 25aa having a larger diameter than the front portion. A position sensor 44 is arranged in the hollow portion 25aa of the output rod 25a to detect the amount of movement or the forward/backward position of the output rod 25a. Although various types of position sensors can be used for the position sensor 44, a magnetic sensor is used in this example.

The position sensor 44 is installed at the tip of the shaft-shaped support member 45b of the sensor mounting member 45 mounted on the unit support member 3. As shown in FIG. The sensor mounting member 45 includes a substrate 45a attached to the unit support member 3 behind the retracted end of the output rod 25a, and a proximal end attached to the substrate 45a so as to protrude vertically from the substrate 45a. and the shaft-like support member 45a inserted into the hollow portion 25aa of the rod 25a.
Two permanent magnets 46 and 47, which serve as sensor targets, are fixed to the output rod 25a so as to be separated from each other in the axial direction of the output rod 25a. The position sensor 44 relatively advances and retreats back and forth within the hollow portion 25aa according to the forward and backward movement of the output rod 25a, thereby reading changes in the magnetic field caused by the movement of the permanent magnets 46 and 47. As shown in FIG. The position sensor 44 is, for example, an analog magnetic sensor, and outputs a sinusoidal detection signal, for example, according to the forward/backward movement of the output rod 25a.
Specifically, the two permanent magnets 46 and 47 are fitted in mounting holes opening on the inner periphery of a bottomed cylindrical magnet mounting member 47 fitted in the hollow portion 25aa of the output rod 25a. , and is attached to the output rod 25a by being prevented from escaping by a sleeve 48. As shown in FIG.
Position sensor 44 and sensor mounting member 45 are covered by sensor housing 49 .

<Other mechanical configurations>
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. 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 and 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.

<About the steering system>
As shown in FIG. 3, this steering system includes the hub unit 1 with steering function according to the first embodiment, and a control device 29 that controls the steering actuator 5 of this hub unit 1 with 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 (steering angle command signal) given from the host control section 32 .
The host controller 32 is a host controller of the steering controller 30. As the host controller 32, for example, an electric control unit (vehicle control unit, abbreviated as VCU) that controls the entire vehicle is applied.

The actuator drive control unit 31 outputs to the motor 26 a current corresponding to the current command signal input from the steering control unit 30 to drive and control the forward/backward position of the output rod 25a of the steering actuator 5. (See FIG. 1) It controls the steering angle of the surrounding hub unit main body 2 . 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 actuator drive control unit 31 configures, for example, 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.
Further, the actuator drive control section 31 performs feedback control using the advancing/retreating position of the output rod 25a detected by the position sensor 44 (see FIG. 7).

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.

<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. 9, in a vehicle with front-wheel steering, it may be set in a suspension 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.
Alternatively, as shown in FIG. 10, the hub unit 1 with steering function may be used for the left and right front wheels 9F, 9F which are steered wheels and the left and right rear wheels 9R, 9R which are non-steered wheels.

<Effect>
According to the hub unit 1 with a steering function configured as described above, the hub unit main body 2 having the hub bearing 15 and having the steering axis A different from the kingpin axis of the steering device 11 (see FIG. 8) that performs normal steering. It is held rotatably around the steered axis A at both upper and lower ends. Further, it is possible to rotate the hub unit main body 2 about the steering axis A by the steering actuator 5 arranged in the hub unit 1 . As a result, the toe angle of the wheels 9 attached to the hub unit body 2 can be freely changed during running with a simple structure.

Since the angles of the left and right wheels 9, 9 (9F, 9F) can be independently and arbitrarily changed according to the running conditions of the vehicle, the motion performance of the vehicle 10 can be improved by appropriately correcting the tire angle. and enable stable and safe driving. In addition, it is also possible to improve fuel efficiency by setting an appropriate wheel angle.
As a specific example, the steering geometry can be changed during running, such as using parallel geometry for high-speed cornering and Ackermann geometry for low-speed cornering. Since the wheel angle can be freely changed during running in this manner, the motion performance of the vehicle 10 can be improved, and the vehicle can run stably and safely. Furthermore, by appropriately changing the steering angle of the left and right steered wheels, the turning radius of the vehicle 10 during turning can be reduced, and the tight turning performance can be improved. Even when driving in a straight line, by adjusting the amount of toe angle according to each situation, the tire angle is toe-in at high speeds to improve driving stability without deteriorating fuel efficiency by directing the tires straight at low speeds and reducing resistance. It is possible to make adjustments such as securing

In order to perform the above control with high accuracy, it is necessary to grasp the angle of the tire more accurately, and for that purpose, it is necessary to grasp the amount of movement of the component parts on the tire side as much as possible. In this embodiment, in order to appropriately manage the angle of the wheels 9 or to check whether the operation is performed according to the command value, the displacement of the output rod 25a of the trapezoidal screw direct-acting mechanism 25 is detected by a position sensor. 44 , and the position sensor 44 is arranged in the hollow portion 25 aa of the output rod 25 a of the linear motion mechanism 25 .
Since the position sensor 44 is used to detect the amount of movement in the linear direction or the forward/backward position in this way, unlike the rotation sensor that detects the rotational position of the motor, direct detection is possible without an error due to the play of the linear motion mechanism 25. It can be detected with high accuracy. In addition, the absolute position can be detected with a compact configuration compared to an absolute type rotation sensor. Moreover, since the position sensor 44 is arranged in the hollow portion 25aa of the output rod 25a of the linear motion mechanism 25, the hollow portion 25aa of the output rod 25a is effectively used, and the position sensor 44 can be operated without requiring a separate installation place. can be installed, and the hub unit 1 with a steering function can be miniaturized.

In addition, according to the steering system provided with this hub unit 1 with a steering function, the driver operates the steering angle of the wheels 9 with the steering wheel 11a, but the host controller 32 of the vehicle 10 adjusts the steering angle of the left and right wheels according to the situation of the vehicle 10. , and the steering control unit 30 outputs a current command signal according to the input (steering angle command signal). Upon receiving the current command signal, the actuator drive control section 31 outputs a motor drive current to the motors of the left and right steering actuators 5 according to the command signal, thereby causing the hub unit main body 2 having the hub bearing 15 for the unit support member 3 to move. change the angle of As a result, it is possible to improve exercise performance and fuel efficiency.

Although not shown, the position sensor 44 may be attached laterally by providing a slit extending in the axial direction in the output rod 25a instead of inserting the position sensor from the rear as shown in FIG. In this case, the board on which the position sensor 44 is attached can be fixed not in a cantilever but in a double-supported position, so that stable sensing is possible even when there are many disturbances such as vibrations.

As mentioned above, although the form for implementing this invention was demonstrated based on embodiment, embodiment disclosed here 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.

2 Hub unit main body 3 Unit support member 5 Steering actuator 6 Knuckle (suspension frame part) 9 Wheel 12, 12R Suspension device 15 Hub bearing 16a Annular portion 16b... Steering shaft portion (steering center part), 25... Linear motion mechanism, 25a... Output rod, 25aa... Hollow part, 44... Position sensor, 45... Sensor mounting member

Claims (4)

a hub unit body having a hub bearing that supports 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 linear motion mechanism in which the output rod advances and retreats,
A position sensor is arranged in the hollow portion of the output rod of the linear motion mechanism to detect the amount of movement or the forward/backward position of the output rod, the position sensor is a magnetic sensor, and the output rod is a magnet serving as a sensor target. is fixed, and the position sensor is fixed to the unit support member and attached to the sensor support member that moves relatively forward and backward in the hollow portion by the forward and backward movement of the output rod. A hub unit with a steering function according to claim 1 and a control device, wherein the control device receives a command signal from a host control unit and outputs a current command signal to a motor that is a driving source of the linear motion mechanism. A steering system comprising: a steering control section; and an actuator drive control section that outputs a current corresponding to the current command signal and applies it to the motor to drive the steering actuator. 3. A vehicle comprising the hub unit with steering function according to claim 1 or the steering system according to claim 2 , wherein the hub unit with steering function is mounted on left and right front wheels. 3. A vehicle comprising the hub unit with steering function according to claim 1 or the steering system according to claim 2 , wherein the hub unit with steering function is mounted on left and right rear wheels.

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