JP6720393B2 - Hub bearing with steering shaft and hub unit with steering function - Google Patents

Description

The present invention relates to Habuyuni' preparative hub bearing and with rolling steering function with the steering shaft provided with a function of performing an auxiliary steering of the steering or rear wheel steering, etc. is added to the steering by the steering apparatus, the fuel consumption Improvement, stability of vehicle drivability and improvement of safety.

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

Vehicle geometry affects driving stability and safety.
For example, Patent Documents 1 and 2 have been proposed for a mechanism in which the steering geometry is variable according to the traveling situation. In Patent Document 1, the steering geometry is changed by relatively changing the knuckle arm and the joint position. In Patent Document 2, it is possible to tilt both the toe angle and the camber angle to arbitrary angles by using two motors. Further, a four-wheel independent steering mechanism is proposed in Patent Document 3.

JP, 2009-226972, A DE 102 01 2206337 specification JP, 2014-061744, A

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

As mentioned above, the steering system of a typical vehicle is mechanically connected to the wheels, so it can generally only take a single fixed steering geometry, which is the intermediate between Ackerman geometry and parallel geometry. Often set to geometrical geometry. However, in this case, the steering angle difference between the left and right wheels becomes insufficient in the low speed range, and 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 between the inner and outer wheels in this way, it will lead to poor fuel efficiency due to poor running resistance and premature wheel wear. There is a problem that is damaged.

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

In Patent Document 2, since two motors are used, the cost increases due to an increase in the number of motors and the control becomes complicated.
Patent Document 3 can be applied only to a vehicle with four-wheel independent steering, and since the hub bearing is cantilevered with respect to the steering shaft, the rigidity is reduced and the steering geometry is reduced due to excessive travel G. It can change.
Further, when a reduction gear is provided on the steered shaft, large power is required. For this reason, although the motor is made large, if the motor is made large, it becomes difficult to dispose the entire body 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 having the auxiliary steering function has a complicated structure because it is intended to arbitrarily change the toe angle or the camber angle of the wheels in the vehicle. Further, it becomes difficult to secure the rigidity, and it is necessary to increase the size in order to secure the rigidity, which increases the weight.

In the vehicle, in order to arbitrarily change the toe angle or the camber angle of the wheels, a complicated structure is required and the number of constituent parts increases.
In order to accommodate a mechanism (hub unit) having a steering function in a limited space inside a wheel, downsizing is required, but there is a concern that the strength of each part will be insufficient. In particular, the steered shaft and its supporting bearings that receive an excessive impact force from the road surface are most easily affected, and it is difficult to secure strength and reliability.
Specifically, as shown in FIG. 10, by downsizing the hub unit, the steered shaft Tg and its supporting bearing Brg are downsized, so that an excessively large external force acts on the hub unit from the road surface. In this case, the steering shaft Tg or the support bearing Brg may become abnormal, and the steering function may deteriorate.

The purpose of this invention, provided with miniaturized hub unit with the steering function, the impact strength against external forces and reliability turning shaft with a hub bearing Ru can be improved and the rolling steering function with Habuyuni' DOO It is to be.

The hub unit with a steering function of the reference proposal example is a hub unit main body having a hub bearing that supports wheels,
A unit support member that is provided in a suspension frame component of the suspension device and that rotatably supports the hub unit body around a steering axis extending in the up-and-down direction;
A rolling actuator that drives the hub unit body to rotate about the steering axis,
The unit support member has an abutting portion with which a part of the hub unit main body comes into an abutting state in the vertical direction in an abnormal state, and the abutting portion is normally in the vertical direction with respect to the hub unit main body. The non-ordinary state in which the hub unit main body is separated from the hub unit and is in the contact state is when an impact load of a certain value or more in the vertical direction acts on the hub unit main body by an external force from the wheel.
The impact load of a certain value or more is an impact load arbitrarily determined by design or the like, and is determined by determining an appropriate impact load by one or both of a test and a simulation, for example.
The following examples can be given when an impact load of a certain value or more in the vertical direction acts on the hub unit body by an external force from the wheels.
(1) When the wheel collides with an obstacle on the road surface, such as riding on a curb during normal driving of the vehicle.
(2) When the vehicle shock absorber cannot absorb the force acting on the ground contact surface of the tire of the wheel in the lateral direction with respect to the traveling direction of the vehicle when the vehicle is turning. This is because in this case, a large moment force is easily transmitted to the hub unit.

With this configuration, the hub unit main body including the hub bearing that supports the wheels can be freely rotated about the turning axis by driving the rolling actuator. Therefore, the wheels can be steered independently, and the toe angle of the wheels can be arbitrarily changed according to the traveling state of the vehicle.
Therefore, it may be used for both steered wheels such as front wheels and non-steered wheels such as rear wheels. When it is used for steered wheels, it is installed on a member whose direction can be changed by the steering device so that it can be added to the steered wheels by the driver's steering wheel operation, and the left and right wheels can be individually or in combination with the left and right wheels. It becomes a mechanism to change the angle.

Further, when turning, it is possible to change the steering angle difference between the left and right wheels according to the traveling speed. For example, the steering geometry can be changed during traveling, such as parallel geometry for turning traveling in the high speed range and Ackermann geometry for turning traveling in the low speed range. As described above, the wheel angle can be arbitrarily changed during traveling, so that it becomes possible to improve the kinetic performance of the vehicle and to travel stably and safely. Further, by appropriately changing the steered angles of the left and right steered wheels, it is possible to reduce the turning radius of the vehicle in turning and improve the small-turn performance.
Furthermore, even when driving straight, the amount of the toe angle can be adjusted according to each situation, so that it is possible to make adjustments such as ensuring running stability without degrading fuel efficiency.

In order to control the behavior of the vehicle in this way, it is necessary to control the steering angle of the wheels accurately, and to increase the rigidity of the entire hub unit while reducing the size so that it can be placed in the limited space inside the wheels. is necessary. However, the downsizing reduces the size of the steered shaft and the bearings that support the steered shaft.Therefore, when an excessively large external force is applied to the hub unit from the road surface, the steered shaft or the steered shaft is supported. There is a concern that an abnormality will occur in the bearing that supports the rudder shaft, and the steering function will be lost.

When an excessively large external force acts on the hub unit from the road surface, a large stress is generated in the root portions of the upper and lower steered shafts, which may cause deformation or the like. Further, when an impact force is applied to the bearing that supports the steered shaft, an indentation may be generated on the bearing raceway surface to prevent smooth rotation, and the steered function may be deteriorated.
The shocking external force mentioned here is generated when a tire or a wheel collides with an obstacle on the road surface, such as when riding on a curb during normal traveling of the vehicle, or when the vehicle turns excessively sharply. The force acting on the ground contact surface of the tire laterally with respect to the traveling direction of the vehicle cannot be absorbed by the vehicle shock absorber. Therefore, a large moment force is easily transmitted to the hub unit.

According to this configuration, the contact portion of the unit support member is vertically separated from the hub unit body in the normal state, and rotation of the hub unit body around the steering axis (steering function) is hindered. There is no such thing.
During an unusual time when an impact load of a certain value or more in the vertical direction acts on the hub unit body due to an external force from the wheels, a part of the hub unit body can be directly contacted with the contact portion of the unit support member in the vertical direction. , The steering function is temporarily stopped while the contact part receives an excessive external force. As a result, it is possible to suppress the occurrence of a large stress on the steered shaft and prevent an abnormality such as deformation of the steered shaft. Further, it is possible to prevent indentation from occurring on the raceway surface of the bearing that supports the steered shaft, and maintain the steered function in a normal state. Therefore, it is possible to reduce the size of the hub unit with a steering function without making it too large.

A part of the hub unit body may be a contacted surface that comes into surface contact with the contact surface of the contact portion. By thus bringing the contact portion and a part of the hub unit body into surface contact with each other, it is possible to more reliably suppress the concentration of stress on the unit support member and the hub unit body.

The unit support member may include a rotation permitting support component that allows the hub unit main body to rotate around the turning axis. A rolling bearing or the like can be applied as the rotation-permitting support component.

The hub unit main body includes an annular portion fixed to an outer peripheral surface of an outer ring that is a fixed ring of the hub bearing, and a mounting shaft portion that protrudes vertically from the outer periphery of the annular portion to mount the rotation permitting support parts. The outer ring having the outer ring may be provided, and a part of the hub unit body that abuts the abutting portion may be the annular portion of the outer ring. In this case, even if an excessive external force is applied to the hub bearing from the road surface, the abutment part of the unit support member and the annular part of the outer ring come into direct contact with each other, so that the axial part of the steering shaft is excessively large. It is possible to suppress the occurrence of various stresses. Further, it is possible to prevent the load supporting the steered shaft from being applied with a certain load or more, and to protect the steered shaft and the bearing.

Steering system of Reference proposed example, a steering system having a steering function with the hub unit of the upper Symbol either configuration, a control device for controlling a rolling actuator of this turning function equipped hub unit , The control device outputs a current command signal corresponding to a given steering angle command signal, and a current corresponding to the current command signal input from the control part to output the current command signal to operate the rolling actuator. And an actuator drive control section for performing drive control.

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

Vehicle Reference proposed example, either or both of the front and rear wheels with a steering function with the hub unit of the upper Symbol either configuration is supported.
For this reason, each of the above-described effects per rolling rudder function with hub unit of this can be obtained. The front wheels are generally steered wheels, but when the hub unit with a steering function of the present invention is applied to the steered wheels, it is effective for adjusting the toe angle during traveling. Although the rear wheels are generally non-steered wheels, when applied to the non-steered wheels, the minimum turning radius during low-speed traveling can be reduced by slightly turning the non-steered wheels .
A hub bearing with a steering shaft according to the present invention is a hub bearing with a steering shaft for rotatably supporting wheels,
An inner ring, an outer ring, and a double row rolling element interposed between the inner and outer rings,
The unit support member is supported so as to be rotatable about a steering axis extending in the vertical direction via two upper and lower rotation permitting support parts,
A part of the hub bearing with a steering shaft is in a contact state with an abutting part which is a part of the unit supporting member in an abnormal state, and is normally separated from the abutting part with a small gap. doing.
The rotation permitting support component may be a rolling bearing.
The abutting state of the abutting portion at the abnormal time may be surface contact.
It may have an action point for rotating the hub bearing with a steering shaft around the steering shaft center.
A hub unit with a steering function of the present invention includes a hub unit main body having a hub bearing that supports wheels,
A unit support member that rotatably supports the hub unit main body around a steering axis extending in the vertical direction,
The unit support member has an abutting portion with which a part of the hub unit main body is in an abutting state in an abnormal state, and the abutting portion normally has a minute gap with respect to the hub unit main body. Are separated.

A hub bearing with a steering shaft according to the present invention is a hub bearing with a steering shaft for rotatably supporting a wheel, and has an inner ring, an outer ring, and a double row rolling element interposed between these inner and outer rings. The support member is rotatably supported about the steering shaft center extending in the vertical direction via two upper and lower rotation permitting support parts, and a part of the hub bearing with the steering shaft is the unit in an abnormal state. The contact portion, which is a part of the support member, is brought into contact with the contact portion, and is normally separated from the contact portion with a minute gap. Therefore, it is possible to reduce the size of the hub unit with a steering function and to improve the strength and reliability against a shocking external force.
Turning function-equipped hub unit of the present invention this comprises a hub unit body having a hub bearing for supporting the wheel, a unit supporting member for rotatably supporting the turning axis around which extends the Ha subunit body in the vertical direction, The unit support member has an abutting portion with which a part of the hub unit main body comes into an abutting state in the vertical direction in an abnormal state, and the abutting portion normally faces the hub unit main body. and, it is away interval through a small gap. Therefore, it is possible to reduce the size of the hub unit with a steering function and to improve the strength and reliability against a shocking external force.

It is a longitudinal cross-sectional view showing the configuration of the hub unit with a steering function and its periphery according to the first embodiment of the present invention. FIG. 3 is a horizontal cross-sectional view showing the configuration of the hub unit with a steering function and its periphery. It is a perspective view showing the 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 hub unit with a steering function. FIG. 6 is a sectional view taken along line VI-VI of FIG. 4. It is an expanded sectional view of a steering shaft part etc. of the hub unit with the same steering function. (A) is an enlarged cross-sectional view showing an enlarged periphery of the contact portion of the hub unit with a steering function in a normal state, and (B) is an enlarged cross-sectional view showing enlarged periphery of the contact portion in the contact state. Is. It is a schematic plan view of an example of a vehicle to which the hub unit with a steering function of the embodiment is applied. It is an expanded sectional view of a steering shaft part etc. of a hub unit of a conventional example.

<First Embodiment>
A hub unit with a steering function according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 8.
<Schematic structure of hub unit with auxiliary steering function>
As shown in FIG. 1, the hub unit 1 with this turning function, the C subunit body 2 is hub bearing with turning axis, the unit support member 3, and the rotation allowing the support part 4, and the steering actuator 5 Equipped with. The unit support member 3 is provided integrally 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 with steering function 1 mounted on a vehicle, the outside in the vehicle width direction of the vehicle is called the outboard side, and the center side in the vehicle width direction of the vehicle is called the inboard side.

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

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

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

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

<About the hub unit body 2>
As shown in FIG. 1, the hub unit body 2 includes a hub bearing 15 for supporting the wheels 9, an outer ring 16, and an auxiliary steering force receiving portion 17 (FIG. 3) described later.
As shown in FIG. 6, the hub bearing 15 includes an inner ring 18, an outer ring 19, and rolling elements 20 such as balls interposed between the inner and outer rings 18 and 19, and members on the vehicle body side and the wheels 9 (see FIG. 1) It has a role of connecting with.

In the illustrated example, the hub bearing 15 is an angular ball bearing in which the outer ring 19 is a fixed ring, the inner ring 18 is a rotating ring, and the rolling elements 20 are double rows. 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 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 steering shaft provided so as to vertically project from the outer periphery of the annular portion 16a. And the steering shaft portions 16b and 16b. Each steered shaft portion 16b is provided coaxially with the steered shaft center A.
As shown in FIG. 2, the brake 21 has a brake rotor 21a and a brake caliper 21b. The brake caliper 21b is attached to two upper and lower brake caliper mounting portions 22 (FIG. 4) formed integrally with the outer ring 19 so as to project in an arm shape.

<Regarding rotation-allowable support parts and unit support members>
As shown in FIG. 6, each rotation-allowable support component 4 is a rolling bearing. In this example, a tapered roller bearing is applied as the rolling bearing. The rolling bearing includes an inner ring 4a fitted to the outer periphery of the steered shaft portion 16b, an outer ring 4b fitted to the unit supporting member 3 as described later, and a plurality of rolling elements interposed between the inner and outer rings 4a and 4b. 4c and.

The unit support member 3 has a unit support member main body 3A and a unit support member combination 3B. A substantially ring-shaped unit support member assembly 3B is detachably fixed to the end of the unit support member body 3A on the outboard side. Partial concave spherical fitting hole forming portions 3a are formed in the upper and lower portions of the inboard side surface of the unit supporting member combined body 3B.

As shown in FIGS. 5 and 6, a partially concave spherical fitting hole forming portion 3Aa is formed in the upper and lower portions of the outboard side end of the unit supporting member main body 3A. As shown in FIG. 3, the unit support member combination 3B is fixed to the end of the unit support member main body 3A on the outboard side, and the fitting hole forming portions 3a and 3Aa (FIG. 5) are combined with each other at the upper and lower portions. As a result, a fitting hole that is continuous with the entire circumference is formed. In addition, in FIG. 3, the unit support member 3 is shown by a dashed line. As shown in FIG. 6, the outer ring 4b is fitted in this fitting hole.

A female screw portion is formed on each of the steered shaft portions 16b so as to extend in the radial direction, and a bolt 23 that is screwed into the female screw portion is provided. A disc-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 that is screwed into the female screw portion, whereby pre-load is applied to each rotation-allowable support component 4. I'm giving. This can increase the rigidity of each rotation-allowable support component 4. 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, the preload can be applied in the same manner as described above.

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

<Abutting part peripheral structure>
FIG. 7 is an enlarged cross-sectional view (section VII in FIG. 1) of a steering shaft portion and the like of the hub unit 1 with a steering function. As shown in FIGS. 7 and 8, the unit support member 3 is normally separated from the annular portion 16a of the outer ring 16 of the hub unit body 2 in the vertical direction (FIG. 8(A)), and is not normally used. The outer ring 16 has an abutment portion 28 with which the annular portion 16a abuts in the vertical direction (FIG. 8(B)). The "non-normal time" is a time when an impact load of a certain value or more in the vertical direction acts on the hub unit body 2 by an external force from the wheels 9 (Fig. 1).

The impact load having a constant value or more is an impact load arbitrarily determined by design or the like, and is determined by determining an appropriate impact load by one or both of a test and a simulation, for example.
The following example can be given as an example in which an external force from the wheels applies an impact load of a certain value or more in the vertical direction to the hub unit body 2.
(1) When the wheel collides with an obstacle on the road surface, such as riding on a curb during normal driving of the vehicle.
(2) When the vehicle shock absorber cannot absorb the force acting on the ground contact surface of the tire of the wheel in the lateral direction with respect to the traveling direction of the vehicle when the vehicle is turning. This is because in this case, a large moment force is easily transmitted to the hub unit. This moment force is a moment force (arrow B in FIG. 1) acting on the hub unit around the vehicle traveling direction.

The outer peripheral surface of the annular portion 16a of the outer ring 16 is a contacted surface 16aa that comes into surface contact with the contact surface of the contact portion 28. A portion of each fitting hole forming portion 3Aa of the unit support member main body 3A that faces the outer peripheral surface of the annular portion 16a via a minute gap δ, and a portion of the annular portion 16a of the unit supporting member combined body 3B. The portion that faces the outer peripheral surface via a minute gap δ is the contact portion 28.

Even when the hub bearing 15 is impacted by an excessively large external force from the road surface and the deformation of the steering shaft portion 16b of the steering shaft exceeds a certain amount, the contact portion 28 of the unit support member 3 and the outer ring 16 are not deformed. By directly contacting the annular portion 16a, the contact portion 28 receives an excessive external force while temporarily stopping the steering function. As a result, it is possible to prevent excessive stress from being generated in the steered shaft portion 16b, prevent the rotation allowable support component 4 that supports the steered shaft portion 16b from being subjected to a certain load, 16b and the rotation permitting support component 4 are protected.

Here, the gap δ between the unit support member 3 and the outer ring 16 is within a range where the stress generated in the steered shaft portion 16b is elastically deformed when the members 3 and 16 contact with each other with an excessive impact force. It is desirable to set it within the range that does not cause indentation on the raceway surfaces of the inner and outer rings 4a and 4b.
On the other hand, in the conventional structure shown in FIG. 10, there is no "contact portion" peculiar to the present application, and an excessive impact force is entirely exerted on the steered shaft portion Tg and its supporting bearing Brg. Therefore, for example, there is a possibility that the steering function is deteriorated due to an abnormality such as a plastic deformation of the steering shaft portion Tg or an indentation on the raceway surface of the support bearing Brg.

<Steering actuator 5>
As shown in FIG. 3, the steering actuator 5 has an actuator body 7 that drives the hub unit body 2 to rotate about the steering axis A (FIG. 1).
As shown in FIG. 2, the actuator body 7 converts the motor 26, the speed reducer 27 that reduces the rotation of the motor 26, and the forward/reverse rotation output of the speed reducer 27 into the reciprocating linear motion of the linear motion output unit 25a. And a linear motion mechanism 25 for 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 or a gear train, 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 a driven pulley 27b is provided in the linear motion mechanism 25. The driven pulley 27b is arranged parallel to the motor shaft. The driving force of the motor 26 is transmitted from the drive pulley 27a to the driven pulley 27b via the belt 27c. The drive pulley 27a, the driven pulley 27b and the belt 27c constitute a winding type speed reducer 27.

A feed screw mechanism such as a slide screw or a ball screw, or a rack and pinion mechanism can be used as the linear motion mechanism 25, and in this example, a feed screw mechanism using a trapezoidal screw is used. The direct-acting mechanism 25 has a feed screw mechanism using the sliding screw of the trapezoidal screw, so that the effect of preventing reverse input from the tire 9b can be enhanced. The actuator body 7 including the motor 26, the speed reducer 27, and the linear motion mechanism 25 is assembled as a subassembly and is detachably attached to the case 6b with bolts or the like. A mechanism that directly transmits the driving force of the motor 26 to the linear motion mechanism 25 without using a speed reducer is also possible.

The case 6b is formed integrally with the unit support member main body 3A as a part of the unit support member 3. The case 6b is formed in a cylindrical shape with a bottom, and is provided with a motor housing portion that supports the motor 26 and a linear motion mechanism housing portion that supports the linear motion mechanism 25. A fitting hole for supporting the motor 26 at a predetermined position in the case is formed in the motor housing portion. The linear motion mechanism housing portion is formed with a fitting hole for supporting the linear motion mechanism 25 at a predetermined position in the case, a through hole for allowing the linear motion output portion 25a to 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 that serves as a shock absorber mounting portion, and the steering device coupling portion 6d that serves as a coupling portion for the steering device 11 (FIG. 2). Have. The shock absorber mounting portion 6c and the steering device coupling portion 6d are also integrally formed on the unit support member main body 3A. A shock absorber mounting portion 6c is formed so as to project above the outer surface of the unit support member main body 3A. A steering device coupling portion 6d is formed so as to project on a side surface portion of the outer surface portion of the unit support member main body 3A.

<Effect>
According to the hub unit 1 with a steering function described above, the hub unit 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 body 7. it can. That is, the hub unit main body 2 rotates the linear motion output portion 25a of the steering actuator 5 through the auxiliary steering force receiving portion 17 connected to the linear motion output portion 25a by moving the linear motion output portion 25a forward and backward by driving the motor 26. To be made.

This rotation is added to the steering by the driver's steering wheel operation, that is, in addition to the rotation of the knuckle 6 around the kingpin axis by the steering device 11, and is performed as an auxiliary steering. You can steer. The toe angle between the left and right wheels 9 and 9 can be arbitrarily changed by changing the auxiliary steering angles of the left and right wheels 9 and 9.

Therefore, it may be used for both steered wheels such as front wheels and non-steered wheels such as rear wheels. When it is used as a steered wheel, it is installed on a member whose direction can be changed by the steering device 11 so as to be added to the steered wheel by the driver's steering wheel operation so that the left and right wheels can be individually operated or the wheels that are interlocked with the left and right wheels. 9 is a mechanism for making a minute angle change. Regarding the angle of the auxiliary steering, a small angle is sufficient to improve the kinetic performance of the vehicle and the stability and safety of running, and it is sufficient even if the auxiliary steering possible angle is ±5 degrees or less. The angle of the auxiliary steering is controlled by the steering actuator 5.

Further, when turning, it is possible to change the steering angle difference between the left and right wheels according to the traveling speed. For example, the steering geometry can be changed during traveling, such as parallel geometry for high-speed turning and Ackermann geometry for low-speed turning. As described above, the wheel angle can be arbitrarily changed during traveling, so that it becomes possible to improve the kinetic performance of the vehicle and to travel stably and safely. By appropriately changing the steered angles of the left and right steered wheels when turning, it is possible to reduce the turning radius of the vehicle and improve the small turning performance.

Furthermore, even when driving straight, the amount of toe angle can be adjusted according to each situation, so that it is possible to make adjustments such as ensuring running stability without lowering running resistance and reducing fuel consumption. In addition, even if a function such as a power source of the hub unit 1 with a steering function occurs during traveling of the vehicle, the vehicle can be moved to a safe place by operating the steering wheel, and safety is ensured.

In the normal state, the contact portion 28 of the unit support member 3 is vertically separated from the annular portion 16a of the outer ring 16 and rotates about the steering axis A of the hub unit body 2 (steering function). Will not be hindered.

During an abnormal time when an impact load of a certain value or more in the vertical direction acts on the hub unit body 2 due to an external force from a wheel, the abutment portion 28 of the unit support member 3 has an annular portion 16a of the outer ring 16 (the hub unit body 2). (A part of) is directly contacted in the vertical direction, and the contact portion 28 receives an excessive external force while temporarily stopping the steering function. Accordingly, abnormal deformation such as the turning shaft portion 16b to suppress a large stress to the turning shaft portion 16b is generated can be prevented from occurring. In addition, it is possible to prevent indentation from being generated on the raceway surfaces of the inner and outer races 4a and 4b of the rolling bearing that supports the steered shaft portion 16b, so that the steered function in the normal state can be favorably maintained. Therefore, it is possible to reduce the size of the hub unit 1 with a steering function without making it too large. Further, by bringing the contact portion 28 of the unit support member 3 and a part of the hub unit body 2 into surface contact with each other, it is possible to more reliably suppress the concentration of stress on the unit support member 3 and the hub unit body 2. obtain.

<About other embodiments>
In the following description, the parts corresponding to the items previously described in the respective embodiments are designated by the same reference numerals, and overlapping 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. The same operation and effect are obtained from the same configuration. Not only the combination of the parts specifically described in each of the embodiments, but also the embodiments may be partially combined with each other as long as the combination does not cause any trouble.

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

<About the steering system>
As shown in FIG. 3, this steering system includes a hub unit 1 with a steering function according to any of the embodiments, and a control device 29 for controlling a steering actuator 5 of the hub unit 1 with a steering function. Equipped with. The control device 29 has a control unit 30 and an actuator drive control unit 31. The control unit 30 outputs a current command signal according to the auxiliary turning angle command signal (turning angle command signal) given from the upper control unit 32.

The higher-order control unit 32 is a higher-order control unit of the control unit 30, and as the higher-order control unit 32, for example, an electric control unit (VCU), which controls the entire vehicle, is used.
Is applied. The actuator drive control unit 31 outputs a current according to the current command signal input from the control unit 30 to drive and control the steering actuator 5. The actuator drive controller 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 based on the ON-OFF duty ratio of the switch element. As a result, the wheels can be slightly changed in angle in addition to steering by the driver's steering wheel operation. Even when driving straight, the amount of toe angle can be adjusted to suit each scene.

The embodiments for carrying out the present invention have been described above based on the embodiments, but the embodiments disclosed this time are exemplifications in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1... Hub unit with steering function 2... Hub unit body (hub bearing with steering shaft)
3... Unit support member 5... Steering actuator 9... Wheel 15... Hub bearing 16aa... Contact surface 28... Contact part 29... Control device 30... Control part 31... Actuator drive control part

Claims (5)

A hub bearing with a steering shaft that rotatably supports wheels,
An inner ring, an outer ring, and a double row rolling element interposed between the inner and outer rings,
The unit support member is supported so as to be rotatable about a steering axis extending in the vertical direction through two upper and lower rotation permitting support parts,
A part of the hub bearing with a steering shaft is in a contact state with an abutting part which is a part of the unit supporting member in an abnormal state, and is normally separated from the abutting part with a small gap. Hub bearing with steering shaft. The hub bearing with a steering shaft according to claim 1, wherein the rotation permitting support component is a rolling bearing. The hub bearing with a steering shaft according to claim 1 or 2, wherein the abutting state of the abutting portion in the non-normal time is a surface contact. The hub bearing with a steering shaft according to any one of claims 1 to 3, wherein the hub bearing with a steering shaft has an action point for rotating the hub bearing with the steering shaft around the steering shaft center. Hub bearing. A hub unit main body having a hub bearing for supporting a wheel;
A unit supporting member that rotatably supports the hub unit main body around a steering axis extending in the vertical direction,
The unit support member has an abutting portion with which a part of the hub unit main body is in an abutting state in an abnormal state, and the abutting portion normally has a minute gap with respect to the hub unit main body. A hub unit with a steering function that is separated from each other.

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