WO2014017089A1

WO2014017089A1 - Auxiliary steering device for vehicle and auxiliary steering method for same, and elevation device for auxiliary wheel

Info

Publication number: WO2014017089A1
Application number: PCT/JP2013/004511
Authority: WO
Inventors: 裕御厨; 三浦　雅博; 量康赤坂; 好夫滝本; 川島　啓一; 一高藤井
Original assignee: 日産自動車株式会社
Priority date: 2012-07-26
Filing date: 2013-07-24
Publication date: 2014-01-30
Also published as: JP5930040B2; JPWO2014017089A1

Abstract

Provided is an auxiliary steering device which makes possible tight-turning movements of a vehicle using a simpler auxiliary wheel. The auxiliary steering device is provided on a vehicle equipped with left/right drive wheels and a third wheel which is separate from said left/right drive wheels. By lowering a non-drive state auxiliary wheel (12) which is supported in the vehicle body, the load of the contact patch of said third wheel is reduced or even brought to zero. In a state in which the third wheel (12) is lowered in this way, the present invention has a drive power differential regulation device which can enable the generation of a drive power differential in said left/right drive wheels.

Description

Auxiliary steering device and auxiliary steering method for vehicle, and lifting device for auxiliary wheel

The present invention is a technology relating to auxiliary steering that makes it possible to make a small turn of the vehicle using auxiliary wheels, and a technology that raises and lowers auxiliary wheels for lifting the third wheel.

As an auxiliary steering device using auxiliary wheels, for example, there is a device described in Patent Document 1.
In order to perform parallel parking of a vehicle in a narrow place, the device described in Patent Document 1 is provided with auxiliary wheels that are different from the wheels used during normal traveling at the front and rear of the vehicle body. And in the said conventional apparatus, while lowering the said auxiliary wheel and raising the rear part of a vehicle body, etc., the vehicle is moved to a horizontal direction by rotationally driving the lowered auxiliary wheel.

JP-A-7-132803

The above-described conventional auxiliary steering device is used by rotationally driving the auxiliary wheel by mounting a hydraulic motor serving as a power source on the axle of the auxiliary wheel in order to allow the vehicle to travel in the lateral direction. It has a configuration. For this reason, the above-described conventional auxiliary steering device requires devices and actuators such as a hydraulic path, a hydraulic pump, and an electromagnetic switching valve, and thus there is a problem that the auxiliary steering device is increased in size and cost.
The present invention pays attention to the above points, and an object of the present invention is to make it possible to move the vehicle by a small turn with a simpler auxiliary wheel.

In order to solve the above-described problems, one aspect of the present invention is provided in a vehicle including left and right drive wheels that are arranged on one of the front side and the rear side of the vehicle and face each other on the left and right. In addition, the auxiliary wheel disposed on the other side of the front side or the rear side of the vehicle in plan view and used without driving, the auxiliary wheel lifting device for raising and lowering the auxiliary wheel with respect to the vehicle body, and the auxiliary wheel are grounded. And a driving force difference adjusting device for generating a driving force difference between the left and right driving wheels.

According to one aspect of the present invention, when a driving force difference is generated between the left and right driving wheels while the auxiliary wheel is grounded, a moment in the yaw direction acts on the vehicle body. At this time, the body portion of the auxiliary wheel position moves in the lateral direction of the vehicle body by the force of the moment. As a result, for example, the vehicle can turn around the driving wheel side having a relatively small driving force. That is, a power unit for rotating the auxiliary wheels is not required, and the configuration around the auxiliary wheels is simple, and the vehicle can be moved in a small direction.

It is the schematic which shows the structure of the vehicle which concerns on embodiment based on this invention. It is a figure explaining the system configuration | structure of the auxiliary steering apparatus of the vehicle which concerns on embodiment based on this invention. It is the figure seen from the vehicle back for explaining the auxiliary wheel which goes up and down. It is a figure explaining the example of the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the structure of an auxiliary operation control part. It is a flowchart figure explaining an example of a process of an auxiliary operation control part. It is a state transition diagram which shows a driver | operator's operation and operation | movement of an auxiliary steering device. It is a top view which shows the example of turning of the vehicle by auxiliary steering. It is a top view which shows the example of turning of the vehicle by auxiliary steering in the case where the rear wheel side is used as a driving wheel and the front side of the vehicle body is lifted by auxiliary wheels. It is a figure which shows the example of the parallel parking using auxiliary steering in the case of lifting the vehicle body front side with an auxiliary wheel. It is a key map explaining vehicles composition using a right-and-left independent parking brake device. It is a conceptual diagram explaining the vehicle structure in the case of using the power source of a driving wheel as an in-wheel motor. It is a top view which shows the optimal example of direction of an auxiliary wheel. It is a conceptual diagram explaining the vehicle structure in case an auxiliary wheel is comprised with a caster wheel. It is a top view which shows the suspension and auxiliary wheel raising / lowering apparatus of a vehicle rear part. It is a rear view which shows the suspension and auxiliary wheel raising / lowering apparatus of a vehicle rear part. It is a top view which shows arrangement | positioning of an auxiliary wheel raising / lowering apparatus. It is a conceptual diagram explaining a steering device. It is a figure explaining a steering operation limiting device. It is a figure which shows the relationship between a pin and a recessed part. It is a figure explaining the structure of an auxiliary operation control part. It is a flowchart figure explaining an example of a process of an auxiliary operation control part. It is a figure explaining a steering operation limiting device. It is a figure which shows the relationship between a pin and a recessed part. It is a figure explaining a steering operation limiting device. It is a figure explaining an optimal target rudder angle. It is a schematic diagram explaining the behavior of the auxiliary wheel during normal traveling. It is the figure which simulated the behavior at the time of protruding over the protrusion at the time of normal driving. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel. It is a figure explaining the raising / lowering mechanism of an auxiliary wheel.

[First Embodiment]
Next, embodiments of the present invention will be described with reference to the drawings.
“1 of the first embodiment”
(Constitution)
FIG. 1 is a schematic diagram showing a configuration of a vehicle according to the present embodiment, and FIG. 2 is a system diagram thereof.
In the present embodiment, as shown in FIG. 1, a vehicle having left and right front wheels 1FL and 1FR and left and right rear wheels 1RL and 1RR and using left and right front wheels 1FL and 1FR as driving wheels will be described as an example. In the present invention, the steering wheel is not particularly limited.
The vehicle according to the present embodiment includes an engine 2 as a power source, an engine control unit 4, a differential gear device 3, and a braking control device 18. The power source of the drive wheels 1FL and 1FR is not limited to the engine 2 and may be an electric motor.

The engine 2 is connected to the axles of the left and right drive wheels 1FL and 1FR via a differential gear device 3. The power of the engine 2 is distributed to the left and right drive wheels 1FL and 1FR by the differential gear device 3. The engine control unit 4 calculates an output command value corresponding to the operation amount of the accelerator pedal 5 and adjusts the throttle opening of the engine 2 so that power corresponding to the calculated output command value is generated.

1 and 2, the brake control device 18 includes a brake control circuit 6, a brake control actuator 7, and left and right brake devices 8 provided individually on the left and right drive wheels 1FL and 1FR. Then, by operating the brake control actuator 7 according to the brake command value output from the brake control circuit 6, the left and right brake devices 8 can apply individual braking forces to the left and right drive wheels 1FL and 1FR. It has become. That is, the brake control circuit 6 sends a command to a brake control actuator 7 having a solenoid for opening and closing a valve in the brake oil passage and a hydraulic pump for the brake, and individually controls the braking force one by one. The brake device 8 is a disc type brake device or the like. The brake device 8 may be an electric brake device.

When the brake control device 18 detects an operation of the brake pedal 9, the brake control device 18 applies a braking force corresponding to the operation amount of the brake pedal 9 to each brake device 8. Further, the braking control device 18 of the present embodiment applies a braking force to one of the left and right front wheels 1FL and 1FR when an operation signal is input from an auxiliary steering control unit described later. However, even if an operation signal is input from the auxiliary steering control unit, the brake control circuit 6 gives priority to the brake control according to the brake operation amount when it detects a brake operation amount that is set in advance by operating the brake pedal 9. To implement.

The vehicle also includes a wheel speed sensor 10 that detects the rotational speeds of the left and right front wheels 1FL and 1FR, and a shift position detection sensor 11 that detects a shift position. The wheel speed sensor 10 detects the wheel speed of each front wheel 1FL, 1FR. The shift position detection sensor 11 detects whether the shift position is a forward position, a neutral position, or a reverse position.
The vehicle includes an auxiliary steering device. The differential gear device 3 and the braking control device 18 also serve as part of the configuration of the auxiliary steering device.
The auxiliary steering device includes left and right auxiliary wheels 12, an auxiliary wheel elevating device 13 that raises and lowers each auxiliary wheel 12 relative to the vehicle body, a lift motor control circuit 14, and an auxiliary steering control unit.

The vehicle also includes an auxiliary steering operation switch 19 that can be operated by a passenger.
As shown in FIG. 1, the left and right auxiliary wheels 12 are arranged on the opposite side of the left and right drive wheels 1FL and 1FR with respect to the vehicle center of gravity G when the auxiliary wheels 12 are grounded in a plan view. Yes. In the present embodiment, the left and right auxiliary wheels 12 are driven in the above-mentioned direction rather than a line connecting ends of the left and right rear wheels 1RL and 1RR closer to the drive wheels 1FL and 1FR (front side in the vehicle front-rear direction). The left and right auxiliary wheels 12 are positioned on the opposite side of the left and right drive wheels 1FL and 1FR with respect to the vehicle center of gravity G by being arranged at positions away from the wheels 1FL and 1FR. Note that the rotating shaft of the auxiliary wheel 12 faces the vehicle front-rear direction at least in a grounded state. The vehicle front-rear direction may be inclined in the vehicle width direction with respect to the longitudinal direction of the vehicle body. The inclination is an angle of less than 45 degrees, for example.

Further, as shown in FIG. 3, the left and right auxiliary wheels 12 are arranged apart from each other in the vehicle width direction in the space between the left and right rear wheels 1RL and 1RR. In the present embodiment, the case where the left auxiliary wheel 12 is arranged close to the left rear wheel 1RL and the right auxiliary wheel 12 is arranged close to the right rear wheel 1RR is illustrated.
The auxiliary wheel lifting / lowering device 13 is a device that supports each auxiliary wheel 12 at the rear part of the vehicle body so as to be movable up and down. The auxiliary wheel lifting / lowering device 13 of the present embodiment supports the auxiliary wheel 12 on the vehicle body by the link members 26 to 28 so as to be able to turn in the vehicle width direction, and drives the auxiliary wheel lift motor from the inner side in the vehicle width direction. The auxiliary wheel 12 is moved up and down by moving the auxiliary wheel 12 so as to go downward as it goes outward in the vehicle width direction. The auxiliary wheel lifting device 13 is provided for each auxiliary wheel 12.

An example of the auxiliary wheel lifting device 13 will be described with reference to FIG. FIG. 4 shows the auxiliary wheel elevating device 13 provided on the left rear wheel side as a representative. The configuration of the auxiliary wheel lifting device 13 on the right rear wheel side is the same.
Here, the rear wheels 1RL and 1RR constituting the third wheel are rotatably supported by the wheel support member 20. The wheel support member 20 is supported via a suspension device 24 so as to be swingable up and down with respect to the vehicle body. FIG. 4 shows an upper link member 21, a lower link member 22, and a shock absorber 23 as examples of members constituting the suspension device 24.

Further, the auxiliary wheel 12 is rotatably attached to the auxiliary wheel support member 25 as shown in FIG. The auxiliary wheel support member 25 and the wheel support member 20 are connected by a first link member 26 so as to be swingable up and down. Further, the auxiliary wheel support member 25 and the vehicle body are connected to each other by the second and

third link members

27 and 28 so as to be swingable up and down.
The second link member 27 is composed of a lift motor whose drive shaft 27a extends and contracts with respect to the motor body 27b. The lift motor 27 is a linear motion device, and the motor main body 27b is connected to the vehicle body so as to be able to swing up and down. It is connected so that it can swing.

Here, the first link member 26 is set such that the connection point to the wheel support member 20 is higher than the connection point to the auxiliary wheel support member 25. Further, the connection point of the third link member 28 to the auxiliary wheel support member 25 is disposed below the connection point of the second link member 27 to the auxiliary wheel support member 25. The first to third link members 26 to 28 are preferably arranged on the same plane.

In the auxiliary wheel lifting / lowering device 13 of the above configuration example, the lift motor 27 extends the drive shaft 27a, so that the auxiliary wheel 12 moves upward about the connection point on the auxiliary wheel support member 25 side of the third link member 28. It turns, that is, rises and is stored in the lower surface of the vehicle body. From this state, the lift motor 27 contracts the drive shaft 27a, so that the auxiliary wheel 12 descends downward by turning downward about the connection point of the third link member 28 on the auxiliary wheel support member 25 side. The auxiliary wheel 12 is grounded. At this time, in the present embodiment, when the drive shaft 27a contracts, the connection point on the auxiliary wheel support member 25 side of the first link member 26 is connected to the auxiliary wheel support member 25 side of the third link member 28. When the auxiliary wheel 12 turns to the wheel side around the point and a component force directed upward is input to the wheel support member 20 through the first link member 26 and the auxiliary wheel 12 is grounded, As a result of the upward force being input to the support member 20, the downward stroke amount of the rear wheels 1RL, 1RR is kept small.

The lift motor control circuit 14 reads the motor position and current value from the lift motor 27 that raises and lowers the auxiliary wheel 12 and controls the position of the lift motor 27.
As shown in FIG. 5, the auxiliary steering control unit 30 is configured as a part of a program of the controller 15 that performs vehicle control. Here, the controller 15 is constituted by a CPU, a ROM, a RAM, and the like, and programs for realizing various processes are stored in the ROM. The controller 15 reads the driver's operation switch, the shift position by the shift operation, and the rotational speed of the wheel by the wheel speed sensor 10. Then, the controller 15 determines the vehicle state based on the signal from the sensor or the like, and communicates with the brake control circuit 6 for controlling the braking force, the lift motor control circuit 14 for raising and lowering the auxiliary wheel 12 and the like through the interface circuit. Command is possible.

As shown in FIG. 5, the auxiliary steering control unit 30 includes an auxiliary wheel lift processing unit 30A and a power difference distribution processing unit 30B.
When the auxiliary wheel lift processing unit 30 A detects that the auxiliary steering operation switch 19 is turned on, the auxiliary wheel lift processing unit 30 A supplies a lowering command to the lift motor control circuit 14. In addition, when the auxiliary wheel lift processing unit 30A detects that the auxiliary steering operation switch 19 is turned off, the auxiliary wheel lift processing unit 30A supplies a lift command to the lift motor control circuit 14. Here, the lift motor control circuit 14 drives the lift motor 27 by the lowering command, rotationally drives the link member by a preset rotation angle so as to turn the auxiliary wheel 12 downward, and the auxiliary wheel by the raising command. The lift motor 27 is driven so that the link member turns by a preset rotation angle so as to turn 12 upward.

When determining that the auxiliary steering operation switch 19 is ON, the power difference distribution processing unit 30B of the present embodiment operates the brake device 8 of the right drive wheel 1FR via the brake control circuit 6, and regardless of the brake operation, A preset braking force is applied to the right drive wheel 1FR.
When the auxiliary steering operation switch 19 is determined to be ON, the power difference distribution processing unit 30B applies a braking force to both the left and right front wheels 1FL and 1FR. Only the braking force may be released.

Next, an example of processing of the auxiliary steering control unit 30 will be described with reference to FIG.
The processing of the auxiliary steering control unit 30 is performed every preset sampling time.
First, in step S10, the auxiliary steering control unit 30 determines whether or not the switch has been operated based on a signal from the auxiliary steering operation switch 19. If it is determined that the auxiliary steering operation switch 19 has been operated, the process proceeds to step S20.
In step S20, it is determined whether or not the vehicle is stopped. When it determines with the vehicle having stopped, it transfers to step S30. On the other hand, if it is determined that the vehicle is not stopped, the process proceeds to step S25.
Here, the vehicle stop determination may be performed, for example, as follows. That is, the vehicle speed is detected based on a signal from the wheel speed sensor 10, and the determination is made based on whether or not the detected vehicle speed is equal to or lower than a preset vehicle speed (for example, 5 Km / h) that can be regarded as the vehicle being stopped.

In step S25, the driver is notified that the brake operation is urged. Thereafter, the process proceeds to step S10.
In step S30, it is determined whether or not the auxiliary steering operation switch 19 has been turned ON. If it is determined that the operation has been turned ON, the process proceeds to step S30. If it is determined that the auxiliary steering operation switch 19 is turned off, the process proceeds to step S100.
In step S 40, the auxiliary wheel lift processing unit 30 A performs control to lower the auxiliary wheel 12 and to ground it. In the present embodiment, a lowering command is supplied to each lift motor 27. As a result, the rear part of the vehicle body is lifted. And the ground load on the rear wheel side is reduced.

Next, in step S50, the power difference distribution processing unit 30B performs a process of applying a braking force to the right front wheel 1FR. The applied braking force is preferably large enough to lock the rotation of the right front wheel 1FR.
Next, in step S60, when it is detected that the auxiliary wheel 12 has been lowered and the braking force has been applied to the right front wheel 1FR, the passenger is informed of information presentation indicating that auxiliary steering is possible. The notification is displayed on a display unit or the like of a navigation device that can be visually recognized by an occupant, or is performed by voice.
Thereafter, the process ends.

On the other hand, when the auxiliary steering operation switch 19 is turned off and the process proceeds to step S100, the power difference distribution processing unit 30B performs a process of releasing the braking force applied to the right front wheel 1FR.
Next, in step S110, the auxiliary wheel lift processing unit 30A performs a process of raising the auxiliary wheel 12 and storing it. In the present embodiment, the lift command is supplied to each lift motor 27.
Next, in step S120, when it is detected that the storage of the auxiliary wheel 12 has been completed and the release of the braking force to the right front wheel 1FR has been completed, an information presentation to the effect that the auxiliary steering process has been canceled is notified to the occupant. The notification is displayed on a display unit or the like of a navigation device that can be visually recognized by an occupant, or is performed by voice.
Thereafter, the process ends.

(Operation other)
Next, with reference to FIG. 7, the state transition of the operation state of the auxiliary steering device accompanying the operation of the driver will be described.
The auxiliary steering device of the present embodiment starts to operate when the occupant operates the auxiliary steering operation switch 19 to ON.
In a normal travelable state, the auxiliary wheel 12 is stored on the vehicle body side and the auxiliary wheel 12 is in a non-grounded state. In this state, the driver moves the vehicle forward or backward by performing an accelerator operation.
When carrying out the auxiliary steering, the driver operates the brake to stop the vehicle, and puts the shift lever into the “N” or “P” range.

Subsequently, when the driver turns on the auxiliary steering operation switch 19, the auxiliary steering control unit 30 is activated, and the auxiliary steering control unit 30 lowers the left and right auxiliary wheels 12 to ground each auxiliary wheel 12. The ground load of the rear wheels 1RL and 1RR is reduced to zero or small by further lifting the vehicle body. Subsequently, the auxiliary steering control unit 30 presents information indicating that auxiliary steering is possible after applying braking force to the right front wheel 1FR to lock the right front wheel 1FR.

When the driver confirms that auxiliary steering is possible, the driver selects whether to turn forward or backward by putting the shift lever into the “D” or “R” range.
Here, in the example of the auxiliary steering device of the present embodiment, since the braking force is applied to the right front wheel 1FR, it is possible to turn right in forward (D range) and turn left in backward (R range). Become.
In addition, when it is set as the structure which provides a braking force to the left front wheel 1FL, it will be in the state in which it can turn to the left by forward (D range), and to the right by reverse (R range).

Here, it is assumed that forward (D range) is selected.
In this state, when the driver steps on the accelerator pedal 5 to transmit the output of the engine 2 to the drive wheels 1FL, 1FR, the driving force is mainly distributed to the left front wheel 1FL side by the differential gear unit 3. As a result, a driving force difference is generated between the left and right front wheels 1FL and 1FR. Due to the difference in driving force between the left and right front wheels 1FL and 1FR, a moment in the yaw direction is generated with respect to the vehicle body. At this time, among the left and right front wheels 1FL and 1FR, the right front wheel 1FR is applied to the braking force, so that only the left front wheel 1FL rolls with the driving force. Thus, the vehicle turns right around the right front wheel 1FR to which the braking force is applied. At this time, the rear part of the vehicle body lifted by the auxiliary wheel 12 moves laterally to the left as the auxiliary wheel 12 rolls due to the force of the moment.

By such auxiliary steering, the vehicle moves in a small turn, thereby enabling parallel parking in a narrow place.
FIG. 8 shows an example of the turning state of the vehicle MM at that time. As shown in FIG. 8, the minimum turning radius is reduced by turning the vehicle MM around the right front wheel 1FR.
Furthermore, when the driver stops the accelerator operation and performs the brake operation, the turning operation of the vehicle is stopped.
Assume that the auxiliary steering operation switch 19 is changed to OFF after the vehicle stops and the driver puts the shift lever into the D range or the P range. Then, the auxiliary steering control unit 30 releases the braking force applied to the right front wheel 1FR and raises the auxiliary wheel 12 to store it on the vehicle body side. Thereafter, the auxiliary steering control unit 30 notifies the occupant of the cancellation of the auxiliary steering.

As described above, according to the auxiliary steering device of the present embodiment, the auxiliary wheel 12 is provided at the lower portion of the vehicle body, and the auxiliary wheel 12 is supported on the road surface by the lifting mechanism, thereby lifting the rear wheel 1RL, 1RR releases the restraining force in the left-right direction with respect to the vehicle body.
In this state, when the driver selects the turning direction by the shift operation and then performs the accelerator operation, a driving force difference is generated between the left and right rear wheels 1RL and 1RR, and a moment in the yaw direction is generated in the vehicle body. At this time, since the braking force is applied to the right front wheel 1FR, the vehicle body can turn around the right front wheel 1FR to which the braking is applied or the vicinity thereof.

At this time, since the auxiliary wheel 12 is in a non-driving free state, the auxiliary wheel 12 rolls in the lateral direction of the vehicle body in a state in which the moment in the yaw direction generated in the vehicle body is not inhibited or small.
As a result, as the minimum turning radius of the vehicle becomes smaller than that in the normal state, the space required for parallel parking is extremely reduced as shown in FIG.
FIG. 10 shows an example of parking in the horizontal direction. In the example shown in FIG. 10, after the vehicle MM is moved forward to the front of the parking position, the vehicle MM is turned and moved forward to be parked at the target position.

(Modification)
(1) Since the left and right rear wheels 1RL and 1RR are lifted by the auxiliary wheel 12 to reduce the ground load, the left and right rear wheels 1RL and 1RR may be driving wheels 1FL and 1FR or driven wheels.
(2) In the above description, the left and right front wheels 1FL and 1FR are illustrated as driving wheels. When the left and right rear wheels 1RL and 1RR are drive wheels, the auxiliary wheel 12 may be disposed on the vehicle body front side.
In this case, for example, setting is made so that braking is applied to the right rear wheel 1RR side. An example of turning of the vehicle MM by auxiliary steering in this case is shown in FIG. In this case, for example, after the vehicle MM is retracted to the front of the parking position, the vehicle MM can be turned as shown in FIG.

(3) In the above description, the case where the braking force is applied to one of the left and right drive wheels 1FL and 1FR by using the braking control device 18 capable of applying the braking force independently on the left and right is illustrated.
As shown in FIG. 11, in a vehicle including a left and right independent parking brake device 40 that can individually actuate a parking brake on left and right driving wheels, the left and right independent parking brake device 40 causes one of the left and right driving wheels to move to one wheel. It is good also as composition which can give braking. In the example of FIG. 11, the drive wheels are exemplified as the left and right rear wheels 1RL and 1RR.
In this case, the driver may select a wheel to be braked, or the auxiliary steering control unit 30 may be operated so as to apply braking to one of the drive wheels 1FL and 1FR.

(4) In the above description, the case where the power source of the drive wheels is the engine 2 is exemplified. The drive wheel power source may be a motor. That is, the vehicle to which the auxiliary steering device of the present invention is applied may be an electric vehicle or a hybrid vehicle.
Further, at this time, as shown in FIG. 12, an in-wheel motor structure in which a drive motor 41 is individually arranged for each of the left and right drive wheels may be employed. In this case, a power difference can be generated between the left and right drive wheels by individually controlling the output torque of the left and right drive motors 41.

(5) Here, the rotation shafts of the left and right auxiliary wheels 12 are arranged to face in the vehicle front-rear direction so that the auxiliary wheels 12 roll in the vehicle lateral direction during auxiliary steering.
However, in this embodiment, since the vehicle body rotates around the right front wheel 1FR, it is preferable to set the rotation axis of the auxiliary wheel 12 to face the right front wheel 1FR as shown in FIG. . In this way, the auxiliary wheel 12 is more easily rolled by directing the rotation shaft to the center at the time of turning. In FIG. 13, symbol L indicates an extension line of the rotation shaft of the auxiliary wheel 12.

(6) At this time, as shown in FIG. 14, the auxiliary wheel 12 and the auxiliary wheel support member 25 may be connected via a rotary bearing 43 to form a caster wheel. In this case, the rotation axis of the auxiliary wheel 12 is freely changed, so that the rotation axis is automatically adjusted to the center at the time of turning.
(7) In the above embodiment, the right driving wheel is described as a wheel to which braking is applied, but the wheel to which braking is applied may be set as the left driving wheel.
(8) In the above description, driving wheels to which braking is applied are set in advance, but driving wheels to which braking is applied may be selected according to a driver's instruction. For example, the drive wheel to which braking is applied may be determined according to the steering direction of the steered wheel when the vehicle is stopped.

(9) In the above-described embodiment, an example is given in which a drive force difference is generated between the left and right drive wheels by applying braking to one drive wheel and applying drive force to the other drive wheel.
The configuration for generating a driving force difference between the left and right driving wheels is not limited to this. For example, the drive force difference may be generated by reversing the rotation directions of the left and right drive wheels. In this case, the vehicle body turns around the center position of the left and right drive wheels.
In addition, the driving force is transmitted to both the left and right driving wheels, but a driving force difference may be generated by changing the transmitted driving force.

Here, the braking force can be regarded as a negative driving force.
Here, when the driving wheels are the front wheels 1FL, 1FR, the rear wheels 1RL, 1RR are the third wheels. When the driving wheels are the rear wheels 1RL and 1RR, the front wheels 1FL and 1FR are the third wheels. Here, in the case of a four-wheel drive vehicle, the auxiliary wheel 12 and the auxiliary wheel elevating device 13 may be provided on both the front wheels 1FL and 1FR and the rear wheels 1RL and 1RR. At this time, if the driving wheels at the time of auxiliary steering are the front wheels 1FL, 1FR, the auxiliary steering on the rear wheels 1RL, 1RR side is operated, and if the driving wheels at the time of auxiliary steering are the rear wheels 1RL, 1RR, The auxiliary steering on the front wheels 1FL and 1FR may be actuated.
The differential gear device 3 and the braking control device 18 constitute a driving force difference adjusting device. The braking control device 18 constitutes a left and right independent braking control device 18.

(Effect of this embodiment)
Next, the effect of this embodiment will be described.
(1) The auxiliary wheel elevating device 13 raises and lowers the auxiliary wheel 12 with respect to the vehicle body. The driving force difference adjusting device can generate a driving force difference between the left and right driving wheels when the auxiliary wheel 12 is grounded.
According to this configuration, the vehicle can be turned with a smaller turning radius than that during normal traveling by including the device that generates the driving force difference and the lifting device of the auxiliary wheel 12.
At this time, since it is possible to turn by performing driving force control using a power source (engine 2, motor, etc.) used in normal traveling of the vehicle, a new power system is not required. Further, since the auxiliary wheel 12 itself is a non-driven driven wheel, the apparatus can be made compact and the cost can be reduced.

(2) The driving force difference adjusting device generates the driving force difference by applying braking to one of the left and right driving wheels and transmitting the driving force to the other wheel.
Here, the addition of braking includes the case where the wheel is not locked.
According to this configuration, the vehicle can be turned around the drive wheel side to which braking is applied.
(3) The driving force difference adjusting device includes a left / right independent braking control device 18 capable of variably controlling the brake pressure individually for the left and right driving wheels, and a power difference from the power source to the left and right driving wheels. A differential gear device for distribution.
According to this configuration, the turning radius can be controlled from the spot turning to the small turn during extremely low speed traveling. That is, since the power is distributed so that the driving force of the driving wheel to which braking is applied becomes relatively small, the turning radius can be changed from on-site turning to small turning depending on the magnitude of the applied braking force. As the braking force increases, the turning radius decreases.

(4) The driving force difference adjusting device includes a left and right independent parking brake device that can individually operate the parking brake for the left and right driving wheels, and a difference that distributes the power from the power source to the left and right driving wheels with a power difference. A moving gear device.
According to this configuration, a braking force can be applied to one of the drive wheels by the driver operating the parking brake.
(5) The driving force difference adjusting device includes an in-wheel motor in which a motor serving as an individual power source is mounted on the left and right driving wheels.
According to this configuration, the driving forces of the left and right wheels can be individually adjusted independently.

(6) In plan view, when the auxiliary wheel 12 is in a state where the auxiliary wheel 12 is grounded, a driving wheel in which the extension line of the rotating shaft of the auxiliary wheel 12 has a relatively small driving force among the left and right driving wheels. Set to go to the side.
According to this configuration, the auxiliary wheel 12 is disposed in a substantially vertical direction with respect to the wheel on which the braking force is applied. As a result, it is possible to reduce the wear of the auxiliary wheel 12.
(7) The auxiliary wheel 12 is a caster wheel whose direction of rotation changes according to input from the road surface.
According to this configuration, there is no need to consider the rotation axis of the auxiliary wheel 12, so there is a degree of freedom in design. In addition, since the rotation axis of the auxiliary wheel 12 is automatically adjusted, wear of the auxiliary wheel 12 can be reduced without turning the direction of the auxiliary wheel 12 according to the center of rotation of the vehicle when turning the auxiliary steering. Is possible.

(8) In plan view, the auxiliary wheel 12 is located on the opposite side of the vehicle center of gravity G from the left and right drive wheels when the auxiliary wheel 12 is grounded.
According to this configuration, it is possible to reduce the ground load of the third wheel (including zero) by lowering the auxiliary wheel 12.
(9) In the plan view, the auxiliary wheel 12 is arranged at a position farther from the driving wheel than a line connecting ends of the left and right third wheels close to the driving wheel.
According to this configuration, by lowering the auxiliary wheel 12, it is possible to more reliably reduce the ground load of the third wheel (including zero).

(10) By lowering the non-driving auxiliary wheel 12 supported by the vehicle body to reduce or reduce the ground load of the third wheel to zero, a driving force difference is applied to the left and right driving wheels. Generate and move the vehicle.
In this case, when a driving force difference is generated between the left and right driving wheels, a moment in the yaw direction acts on the vehicle body. At this time, since the ground contact load of the third wheel is reduced or made zero by the auxiliary wheel 12, the vehicle body portion at the position of the auxiliary wheel 12 moves in the lateral direction of the vehicle body by the force of the moment. As a result, for example, the vehicle can turn around the driving wheel side having a relatively small driving force. As a result, the vehicle can be turned with a small turning radius, that is, with a minimum turning radius reduced. In addition, since the auxiliary wheel 12 is used in a non-driven state (driven wheel state), a power device that rotationally drives the auxiliary wheel 12 becomes unnecessary, and the configuration around the auxiliary wheel 12 becomes a simple configuration.

"2 of the first embodiment"
Next, another embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the same copy as the said embodiment.
The basic configuration of the present embodiment is the same as 1 in the first embodiment. However, the arrangement of auxiliary wheels when possible is different.
(Constitution)
FIG. 15 is a top view showing the suspension and auxiliary wheel lifting device 13 at the rear of the vehicle, and FIG. 16 is a rear view thereof. In this example, the auxiliary wheel elevating device 13 is provided for each of the left and right rear wheels. In FIG. 15, which is a top view, a mechanism for sliding the link 27, a lift motor 29, and the like are omitted.
Here, the rear wheels 1RL and 1RR of the present embodiment are rotatably supported by the wheel support member 20. The wheel support member 20 is supported by the vehicle body so as to be able to swing up and down via a leaf-rigid suspension device.

The auxiliary wheel 12 is rotatably attached to the auxiliary wheel support member 25 as shown in FIG. The auxiliary wheel support member 25 and the wheel support member 20 are connected by a first link member 26 so as to be swingable up and down. Further, the auxiliary wheel support member 25 and the vehicle body are connected to each other by the second and

third link members

27 and 28 so as to be swingable up and down. The auxiliary wheel support member 25 and the vehicle body are connected to the second and

third link members

27 and 28 by, for example, ball joints.

A lift motor 29 is fixed to the lower surface of the vehicle body. The lift motor 29 is a linear motion device, and the tip of the link member 27 is rotatably connected to a sliding table.
As shown in FIG. 17, in a plan view, when the auxiliary wheel 12 is lowered and the auxiliary wheel 12 is in contact with the ground, the extension line of the rotation shaft of the auxiliary wheel 12 is relatively driven among the left and right driving wheels. It is set so as to go to the drive wheel side where the force becomes smaller. In addition, the turning direction (operating direction) of the auxiliary wheel when the auxiliary wheel lifting device 13 moves up and down and retracts is set to be perpendicular to the rotation axis of the auxiliary wheel 12. That is, as shown in FIG. 15, the rolling direction of the auxiliary wheels 12 is the vehicle width direction so that the rotating shaft of each auxiliary wheel 12 faces the drive wheel 1FR regardless of whether the auxiliary wheels 12 are stored or grounded. On the other hand, the angles α and β are given in the vehicle longitudinal direction in plan view.

Specifically, as shown in FIG. 17, in a plan view, the extension line of the rotation shaft of the auxiliary wheel 12 in the vehicle width direction is on the driving wheel side where the driving force is relatively small among the left and right driving wheels. It sets so that it may go, and it is set so that it may raise / lower by turning in the direction orthogonal to the said rotating shaft. In this case, as shown in FIG. 15, the first to third link members 26 to 28 are not arranged on the same plane.

(Function and effect)
If the turning direction of the auxiliary wheel is raised or lowered in the vehicle width direction, the auxiliary shaft's rotating shaft extension line faces the vehicle longitudinal direction when the auxiliary wheel is installed. The load applied when moving up and down is increased.
On the other hand, according to the configuration of the above-described embodiment, it is possible to reduce the reaction force from the ground that is received when the auxiliary wheel 12 is raised and lowered, and when the auxiliary wheel 12 is grounded, wear during turning Can be reduced. As a result, the load applied when raising and lowering the auxiliary wheel elevating device 13 is reduced, and the output of the motor can be reduced.

That is, with the auxiliary wheel turning downward and grounded, the auxiliary wheel does not turn and the extension line of the rotating shaft of the auxiliary wheel 12 has a relatively small driving force among the left and right driving wheels. Thus, the wear of the auxiliary wheel can be reduced, and the input to the auxiliary wheel lifting device 13 that supports the auxiliary wheel can be drastically reduced. The same applies to the case where the grounded auxiliary wheel is raised to store the auxiliary wheel.

Here, the lift motor 29 of the present embodiment is illustrated as being set to slide in the vehicle left-right direction.
In a plan view, the set angle that is the direction in which the lift motor 29 slides can be set to be inclined with respect to the vehicle left-right direction. In order to reduce the movable range of the rotation supported end of each link member, the angle α formed by the left auxiliary wheel 12 far from the brake wheel 1FR from the angle parallel to the vehicle left-right direction with respect to the vehicle left-right direction is the brake wheel It is set to be larger than the angle β formed by the right auxiliary wheel on the side close to 1FR.

“Second Embodiment”
Next, another embodiment of the present invention will be described with reference to the drawings.
"1 of the second embodiment"
(Constitution)
The basic configuration of this embodiment is the same as that of the first embodiment as shown in FIGS.
The vehicle also includes a steering device. As shown in FIG. 18, the steering device includes a steering wheel 39, a steering shaft 31, and a steering rack 36.

The steering wheel 39 is a steering operator that a driver performs a steering operation. The steering shaft 31 has an upper end connected to the steering wheel 39. The lower end portion of the steering shaft 31 is connected to the upper end portion of the steering intermediate shaft 34, and the lower end portion of the steering intermediate shaft 34 is connected to the steering rack 36 via a pinion gear. Then, the rotation of the steering wheel 39 is converted into a linear motion of the steering rack 36 by the rack and pinion mechanism. The left and right ends of the steering rack 36 are connected via a tie rod 50 to a knuckle arm 51a of a knuckle 51 that rotatably supports the steered wheels 1FL and 1FR. In the present embodiment, the steered wheels 1FL and 1FR are the front wheels 1FL and 1FR which are drive wheels. Here, the steering shaft 31, the steering intermediate shaft 34, the pinion gear, the steering rack 36, and the tie rod 50 form a steering transmission path for transmitting the steering of the steering wheel 39 to the steered wheels 1FL and 1FR.

As shown in FIG. 19, the steering shaft 31 is rotatably disposed in the steering column 32. A steering electric motor 33 is attached to the steering column 32. The steering electric motor 33 is configured to be able to input a steering torque to the steering shaft 31.
The vehicle includes a steering operation restriction device. The steering operation restriction device of the present embodiment has a mechanism for restricting the rotational displacement of the steering shaft 31 and restricts the rotation (movement) of the steering wheel 39 by restricting the rotational displacement of the steering shaft 31.
As shown in FIG. 20, the steering operation restriction device includes a recess 31 a formed in the steering shaft 31, a pin 40 a, and an advance / retreat mechanism 40. The advance / retreat mechanism 40 includes an electromagnetic solenoid 40c.

At the predetermined axial position in the longitudinal direction of the steering shaft 31, two or more concave portions 31a are formed along the circumferential direction as shown in FIG. In the present embodiment, the recess 31a is formed every 90 degrees in the circumferential direction. Further, the steering column 32 is formed with a notch 32a at a position that can be opposed to one of the recesses 31a in the radial direction as the steering shaft 31 rotates. As a result, as the steering shaft 31 rotates, the recesses 31a sequentially face the notches 32a.

The pin 40a has such a size that it can pass through the notch 32a and can be inserted into the recess 31a. The pin 40a is attached to the tip of the advance / retreat shaft 40b of the electromagnetic solenoid 40c, and the pin 40a is directed to the surface of the steering shaft 31 through the notch 32a by the advance / retreat of the advance / retreat shaft 40b accompanying the operation of the electromagnetic solenoid 40c. To advance and retreat. That is, when a current is supplied to the electromagnetic solenoid 40c as a lock command, the advance / retreat shaft 40b extends and the pin 40a is pressed against the surface of the steering shaft 31. When the current to the electromagnetic solenoid 40c is interrupted as a lock release command, the advance / retreat shaft 40b is contracted by the elastic force of the spring 40d and the pin 40a is separated from the steering shaft 31.
The electromagnetic solenoid 40c is supported by the steering column 32, for example.

The vehicle includes an auxiliary steering device. The differential gear device 3 and the braking control device 18 also serve as part of the configuration of the auxiliary steering device.
The auxiliary steering device includes left and right auxiliary wheels 12, an auxiliary wheel elevating device 13 that raises and lowers each auxiliary wheel 12 relative to the vehicle body, a lift motor control circuit 14, and an auxiliary steering control unit.
The vehicle also includes an auxiliary steering operation switch 19 that can be operated by a passenger.
The left and right auxiliary wheels 12 and the lifting mechanism thereof are the same as in the other embodiments, and thus the description thereof is omitted here.

The auxiliary steering control unit 30 is configured as a partial program of the controller 15 that performs vehicle control. Here, the controller 15 is constituted by a CPU, a ROM, a RAM, and the like, and programs for realizing various processes are stored in the ROM. The controller 15 reads the driver's operation switch, the shift position by the shift operation, and the rotational speed of the wheel by the wheel speed sensor 10. Then, the controller 15 determines the vehicle state based on the signal from the sensor or the like, and communicates with the brake control circuit 6 that controls the braking force, the lift motor control circuit 14 that raises and lowers the auxiliary wheels 12 and the like through the interface circuit. Command is possible.

As shown in FIG. 21, the auxiliary steering control unit 30 includes an auxiliary wheel lift processing unit 30A, a power difference distribution processing unit 30B, and a steering lock processing unit 30C.
When the auxiliary wheel lift processing unit 30 A detects that the auxiliary steering operation switch 19 is turned on, the auxiliary wheel lift processing unit 30 A supplies a lowering command to the lift motor control circuit 14. In addition, when the auxiliary wheel lift processing unit 30A detects that the auxiliary steering operation switch 19 is turned off, the auxiliary wheel lift processing unit 30A supplies a lift command to the lift motor control circuit 14. Here, the lift motor control circuit 14 drives the lift motor 27 by the lowering command, rotationally drives the link member by a preset rotation angle so as to turn the auxiliary wheel 12 downward, and the auxiliary wheel by the raising command. The lift motor 27 is driven so that the link member turns by a preset rotation angle so as to turn 12 upward.

When the steering lock processing unit 30C detects that the auxiliary steering operation switch 19 is turned on, it supplies a lock command (current supply command) to the electromagnetic solenoid 40c and presses the pin 40a against the surface of the steering shaft 31. . When the steering lock processing unit 30C detects that the auxiliary steering operation switch 19 is turned off, the steering lock processing unit 30C supplies a lock release command (current cutoff command) to the electromagnetic solenoid 40c so that the pin 40a is separated from the steering shaft 31. Evacuate.

Next, an example of processing of the auxiliary steering control unit 30 will be described with reference to FIG.
The processing of the auxiliary steering control unit 30 is performed every preset sampling time.
First, in step S10, the auxiliary steering control unit 30 determines whether or not the switch has been operated based on a signal from the auxiliary steering operation switch 19. If it is determined that the auxiliary steering operation switch 19 has been operated, the process proceeds to step S20.

In step S20, it is determined whether or not the vehicle is stopped. When it determines with the vehicle having stopped, it transfers to step S30. On the other hand, if it is determined that the vehicle is not stopped, the process proceeds to step S25.
Here, the vehicle stop determination may be performed, for example, as follows. That is, the vehicle speed is detected based on the signal from the wheel speed sensor 10, and the determination is made based on whether or not the detected vehicle speed is equal to or lower than a preset vehicle speed (for example, 5 km / h) that can be considered that the vehicle is stopped.

Next, in step S50, the power difference distribution processing unit 30B performs a process of applying a braking force to the right front wheel 1FR. The applied braking force is preferably large enough to lock the rotation of the right front wheel 1FR.
Next, in step S55, the steering lock processing unit 30C outputs a lock command (current supply command) to the electromagnetic solenoid 40c. As a result, the advance / retreat shaft 40 b extends and the pin 40 a is pressed against the steering shaft 31. In this state, when the steering shaft 31 is rotationally displaced along with the rotation of the steering wheel 39, the pin 40a is inserted into any one of the concave portions 31a within a rotational range of less than 90 degrees, and the rotational displacement of the steering shaft 31 beyond that. Is regulated.

Next, in step S60, when it is detected that the auxiliary wheel 12 has been lowered and the braking force has been applied to the right front wheel 1FR, the passenger is informed of information presentation indicating that auxiliary steering is possible. The notification is displayed on a display unit or the like of a navigation device that can be visually recognized by an occupant, or is performed by voice.
Thereafter, the process ends.
On the other hand, when the auxiliary steering operation switch 19 is turned off and the process proceeds to step S100, the power difference distribution processing unit 30B performs a process of releasing the braking force applied to the right front wheel 1FR.

Next, in step S110, the auxiliary wheel lift processing unit 30A performs a process of raising the auxiliary wheel 12 and storing it. In the present embodiment, the lift command is supplied to each lift motor 27.
Next, in step S115, the steering lock processing unit 30C outputs a lock release command (current cutoff command) to the electromagnetic solenoid 40c. As a result, the advancing / retracting shaft 40 b contracts and the pin 40 a is displaced in a direction away from the steering shaft 31. As a result, the restriction on the rotation of the steering shaft 31 is released.
Next, in step S120, when it is detected that the storage of the auxiliary wheel 12 has been completed and the release of the braking force to the right front wheel 1FR has been completed, an information presentation to the effect that the auxiliary steering process has been canceled is notified to the occupant. The notification is displayed on a display unit or the like of a navigation device that can be visually recognized by an occupant, or is performed by voice.
Thereafter, the process ends.
Other configurations are the same as those in the above embodiment.

(Operation other)
Next, the state transition of the operation state of the auxiliary steering device according to the driver's operation will be described.
The auxiliary steering device of the present embodiment starts to operate when the occupant operates the auxiliary steering operation switch 19 to ON.
In a normal travelable state, the auxiliary wheel 12 is stored on the vehicle body side and the auxiliary wheel 12 is in a non-grounded state. In this state, the driver moves the vehicle forward or backward by performing an accelerator operation.
When carrying out the auxiliary steering, the driver operates the brake to stop the vehicle, and puts the shift lever into the “N” or “P” range.

Subsequently, when the driver turns on the auxiliary steering operation switch 19, the auxiliary steering control unit 30 is activated, and the auxiliary steering control unit 30 lowers the left and right auxiliary wheels 12 to ground each auxiliary wheel 12. The ground load of the rear wheels 1RL and 1RR is reduced to zero or small by further lifting the vehicle body. Subsequently, the auxiliary steering control unit 30 applies a braking force to the right front wheel 1FR to place the right front wheel 1FR in a locked state. Furthermore, the auxiliary steering control unit 30 presents information indicating that auxiliary steering is possible after the pin 40a is pressed from the radial direction toward the steering shaft 31.

By such auxiliary steering, the vehicle moves in a small turn, thereby enabling parallel parking in a narrow place.
FIG. 8 shows an example of the turning state of the vehicle MM at that time. As shown in FIG. 8, the minimum turning radius is reduced by turning the vehicle MM around the right front wheel 1FR.
At this time, when the moment is generated by the auxiliary steering, a steering reaction force in a direction opposite to the yaw moment is input to the front wheel steering system. For this reason, the steering shaft 31 is rotationally displaced. However, before the steering shaft 31 is rotationally displaced by 90 degrees at the maximum, the pin 40a faces the recess 31a, and the pin 40a is inserted into the facing recess 31a. The rotation of the steering shaft 31 is restricted. Thereafter, the rotation of the steering shaft 31 is restricted, that is, the rotation of the steering wheel 39 is restricted. As a result, the unexpected rotational displacement of the steering wheel 39 during auxiliary steering is limited. As a result, it is possible to reduce a sense of incongruity regarding the behavior of the steering wheel 39 during auxiliary steering to the driver.

Furthermore, when the driver stops the accelerator operation and performs the brake operation, the turning operation of the vehicle is stopped.
Assume that the auxiliary steering operation switch 19 is changed to OFF after the vehicle stops and the driver puts the shift lever into the D range or the P range. Then, the auxiliary steering control unit 30 releases the braking force applied to the right front wheel 1FR and raises the auxiliary wheel 12 to store it on the vehicle body side. Further, the auxiliary steering control unit 30 releases the lock of the steering shaft 31, and allows the rotational displacement of the steering wheel 39 to be allowed. Thereafter, the auxiliary steering control unit 30 notifies the occupant of the cancellation of the auxiliary steering.

As described above, according to the auxiliary steering device of the present embodiment, the auxiliary wheel 12 is provided at the lower portion of the vehicle body, and the auxiliary wheel 12 is supported on the road surface by the lifting mechanism, thereby lifting the rear wheel 1RL, 1RR releases the restraining force in the left-right direction with respect to the vehicle body.
In this state, when the driver selects the turning direction by the shift operation and then performs the accelerator operation, a driving force difference is generated between the left and right rear wheels 1RL and 1RR, and a moment in the yaw direction is generated in the vehicle body. At this time, since the braking force is applied to the right front wheel 1FR, the vehicle body can turn around the right front wheel 1FR to which the braking is applied or the vicinity thereof.
At this time, since the auxiliary wheel 12 is in a non-driving free state, the auxiliary wheel 12 rolls in the lateral direction of the vehicle body in a state in which the moment in the yaw direction generated in the vehicle body is not inhibited or small.
As a result, as the minimum turning radius of the vehicle becomes smaller than that in the normal state, the space required for parallel parking is extremely reduced as shown in FIG.

(Modification)
(1) In the above embodiment, the steering wheel 39 is exemplified as the steering operator. The steering operator may be composed of a stick-like operator.
(2) The steered wheel may be a rear wheel constituting the third wheel. When the steering wheel is a rear wheel, the ground contact load of the rear wheel is reduced to zero or reduced by the auxiliary wheel 12, and the rear wheel whose load is reduced due to a small turning moment by auxiliary steering using the auxiliary wheel 12 is shaken. It becomes easy. On the other hand, in this embodiment, the rotation of the steering wheel 39 is restricted as described above, so that the driver does not need to hold the steering wheel 30 firmly. Further, the steering configuration may be a configuration employing a steering-by-wire system.

Here, when the driving wheels are the front wheels 1FL, 1FR, the rear wheels 1RL, 1RR are the third wheels. When the driving wheels are the rear wheels 1RL and 1RR, the front wheels 1FL and 1FR are the third wheels. Here, in the case of a four-wheel drive vehicle, the auxiliary wheel 12 and the auxiliary wheel elevating device 13 may be provided on both the front wheels 1FL and 1FR and the rear wheels 1RL and 1RR. At this time, if the driving wheels at the time of auxiliary steering are the front wheels 1FL, 1FR, the auxiliary steering on the rear wheels 1RL, 1RR side is operated, and if the driving wheels at the time of auxiliary steering are the rear wheels 1RL, 1RR, The auxiliary steering on the front wheels 1FL and 1FR may be actuated.
The differential gear device 3 and the braking control device 18 constitute a driving force difference adjusting device. The braking control device 18 constitutes a left and right independent braking control device 18. The steering wheel 39 constitutes a steering operator.

(Effect of this embodiment)
Next, the effect of this embodiment will be described.
(1) The auxiliary wheel 12 is disposed at a position closer to the third wheel than the driving wheel in plan view, and is used without being driven. The auxiliary wheel lifting device lifts and lowers the auxiliary wheel 12 with respect to the vehicle body. The auxiliary wheel elevating device and the driving force difference adjusting device can generate a driving force difference between the left and right driving wheels when the auxiliary wheel 12 is grounded. The steering operation restriction device restricts the movement of the steering operator when the auxiliary wheel 12 is grounded.
According to this configuration, when the vehicle turns in a small turn by the auxiliary steering using the auxiliary wheels 12, the movement of the steering operator such as an unexpected touching movement is reduced by restricting the movement of the steering operator. Is possible. That is, the vehicle can turn on the spot without causing the driver to perform an operation of holding the steering operator more than necessary.

(2) The steering operator is a steering wheel 39. The movement of the steering operator is a rotational displacement of the steering wheel 39.
According to this configuration, an unexpected rotational displacement of the steering wheel 39 during auxiliary steering by the auxiliary wheels 12 can be limited.
(3) The steering operation restriction device includes two or more recesses 31a formed on the steering shaft 31 that is rotationally displaced as the steering wheel 39 rotates and arranged in the circumferential direction, and a pin 40a that can be inserted into the recess 31a. And an advancing / retracting mechanism 40 for advancing and retracting the pin 40a toward the steering shaft 31 at an axial position where the concave portion 31a is formed in the steering shaft 31.
According to this configuration, the rotation of the steering wheel can be restricted during auxiliary steering by the auxiliary wheel 12.

"2 of the second embodiment"
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
The basic configuration of the present embodiment is the same as 1 in the second embodiment. However, the mechanism of the steering operation restriction device is different. The other configuration is the same as that of 1 of the second embodiment.
Next, the steering operation restriction device of this embodiment will be described with reference to FIGS.
The steering operation restriction device of this embodiment restricts the rotational displacement of the steering wheel 39 by restricting the displacement of the steering rack 36 that is displaced in the vehicle width direction by the rotation of the steering wheel 39.

The steering operation restriction device of this embodiment will be described.
The steering operation restriction device of this embodiment includes a recess 36a formed in the steering rack 36, an advance / retreat mechanism 41, and a pin 42a.
As shown in FIG. 24, the steering rack 36 is formed with two or more recesses 36a along the longitudinal direction (axial direction). The two or more recesses 36a are arranged such that the two or more recesses 36a are accommodated in a length that allows relative displacement in the axial direction of the steering rack 36.

In the advance / retreat mechanism 41, one end of a pair of substantially C-shaped actuating parts 42 (clamping parts) is connected to a rotational displacement, and the connecting part is used as a fulcrum to rotationally displace the pair of actuating parts. The other end is configured to approach and separate. Then, a locking motor 41a is provided, and the locking motor 41a drives the pair of operating portions 42 so that the other end portions of the pair of operating portions 42 are separated from each other. The other end of the one operating part 42 sandwiches the steering rack 36 from above and below, and the other end of the upper operating part 42 constitutes a pin 42a.

When a lock command is input, the locking motor 41a is driven so that the pair of operating parts 42 approach each other and presses the pin 42a (the other end of the upper operating part 42) against the steering rack 36. . Further, when a lock release command is input, the locking motor 41a is driven so that the pair of operating parts 42 are separated from each other, thereby separating the pin 42a from the steering rack 36. The locking motor 41a is fixed to the vehicle body.
Other configurations are the same as those of the first embodiment.

(Operation etc.)
When the driver turns on the auxiliary steering operation switch 19, the auxiliary steering control unit 30 is activated, and the auxiliary steering control unit 30 lowers the left and right auxiliary wheels 12 to ground each auxiliary wheel 12. By lifting the vehicle body, the ground load of the rear wheels 1RL and 1RR is reduced to zero or small. Subsequently, the auxiliary steering control unit 30 applies a braking force to the right front wheel 1FR to place the right front wheel 1FR in a locked state. Further, the auxiliary steering control unit 30 presents information indicating that auxiliary steering is possible after the other end portion (pin) of the upper operation unit 42 is pressed against the steering rack 36.

At this time, when the moment is generated by the auxiliary steering, a steering reaction force in a direction opposite to the yaw moment is input to the steering system of the front wheels. For this reason, the steering rack 36 is linearly displaced in the axial direction (vehicle width direction). At this time, due to the displacement of the steering rack 36, the other end portion (pin 42a) of the upper operating portion 42 faces the concave portion 36a, and the pin 42a is inserted into the opposed concave portion 36a, so that the steering rack 36 more than that. The linear displacement is regulated. Thereafter, the displacement of the steering rack 36 is restricted, that is, the rotation of the steering wheel 39 is restricted. As a result, the unexpected rotational displacement of the steering wheel 39 during auxiliary steering is limited. As a result, it is possible to reduce a sense of incongruity regarding the behavior of the steering wheel 39 during auxiliary steering to the driver.

When the driver turns the auxiliary steering operation switch 19 “OFF”, the locked state of the steering rack 36 is released.
Other operations are the same as those in the second embodiment.
Here, the recess 36a, the pair of operating parts 42, and the advance / retreat mechanism 41 constitute a steering operation restriction device. The other end of the upper operating portion 42 constitutes the pin 42a.

(Effect of this embodiment)
In addition to the effect of 1 of the said 2nd Embodiment, this embodiment has the following effect.
(1) The steering operation limiting device is formed in the steering rack 36 that is displaced in the vehicle width direction with the rotation of the steering wheel 39 and is arranged along the longitudinal direction of the steering rack 36, and the concave portion 36a. And an advancing / retracting mechanism 41 for advancing and retracting the pin 42a toward and away from the steering rack 36 at a circumferential position where the recess 36a is formed in the steering rack 36.
According to this configuration, the lock position can be set with a finer resolution than when the rotation of the steering shaft 31 is restricted.
The reason is that in the case of the steering shaft 31, it is taken in the circumferential direction, but in the case of the steering rack 36, the recess 36 a can be set in the longitudinal direction.

“3 of the second embodiment”
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
The basic configuration of the present embodiment is the same as 1 in the second embodiment. However, the steering operation restriction device is different. The other configuration is the same as that of 1 of the second embodiment.
In the present embodiment, without using a dedicated device for the steering operation limiting device, as shown in FIG. 25, the steering electric motor 33 applies a motor torque opposite to the steering direction to the steering wheel 39 as described above. The rotation of the steering wheel 39 is limited.

Here, the steering electric motor 33 may be a power steering electric motor or a reaction force applying motor.
When the steering lock processing unit 30 C of the present embodiment detects that the auxiliary steering operation switch 19 is turned on, the steering lock processing unit 30 C inputs a motor torque such that the steering shaft 31 is fixed to the steering electric motor 33 to the steering shaft 31. A control command is issued.
For example, the steering angle that is the control target at this time is set to the steering angle zero (neutral position), the current steering angle is read from the steering angle sensor 38, and the steering position is near the steering angle zero (substantially approximately) based on the read steering angle. Servo-controlled to an angle (neutral position). The steering angle that is the control target may be the steering angle when the auxiliary steering operation switch 19 is turned on.

Further, when the steering lock processing unit 30C detects that the auxiliary steering operation switch 19 is turned off, the steering lock processing unit 30C cancels the application of the steering lock motor torque.
Here, the optimum target rudder angle θf will be described with reference to FIG.
The sum of the caster rail and the pneumatic trail calculated from the suspension geometry of the front wheel (the right front wheel in the figure) that generates the braking force is the trail l, and the distance between the front axles is the front tread base e. Assuming that the steered angle θf of the drive wheels is used, the steered angle at which the steering force fluctuation is minimized can be obtained from the following equation.
θf = arctan (l / e)
Therefore, the motor torque input from the steering electric motor 33 to the steering shaft 31 may be feedback-controlled so that the steering angle of the steering wheel 39 becomes the target steering angle θf.
Here, the steering electric motor 33 constitutes a steering operation limiting device.

(Effect of this embodiment)
In addition to the effect of 1 of the said 2nd Embodiment, this embodiment has the following effect.
(1) The steering operation restriction device restricts the movement of the steering wheel 39 by adding the motor torque output from the steering electric motor 33 to the steering wheel 39.
According to this configuration, a dedicated device for limiting the steering operation becomes unnecessary. This leads to point costs.

“Third Embodiment”
Next, another embodiment of the present invention will be described with reference to the drawings.
"1 of the third embodiment"
(Constitution)
The basic configuration of the vehicle of this embodiment is the same as that of the first embodiment, as shown in FIGS.
FIG. 1 is a schematic diagram showing a configuration of a vehicle according to the present embodiment, and FIG. 2 is a system diagram thereof.
In the present embodiment, as shown in FIG. 1, a vehicle having left and right front wheels 1FL and 1FR and left and right rear wheels 1RL and 1RR and using left and right front wheels 1FL and 1FR as driving wheels will be described as an example. In the present invention, the steering wheel is not particularly limited.

The vehicle according to the present embodiment includes an engine 2 as a power source, an engine control unit 4, a differential gear device 3, and a braking control device 18. The power source of the drive wheels 1FL and 1FR is not limited to the engine 2 and may be an electric motor.
The engine 2 is connected to the axles of the left and right drive wheels 1FL, 1FR via a differential gear device 3. The power of the engine 2 is distributed to the left and right drive wheels 1FL and 1FR by the differential gear device 3. The engine control unit 4 calculates an output command value corresponding to the operation amount of the accelerator pedal 5 and adjusts the throttle opening of the engine 2 so that power corresponding to the calculated output command value is generated.

When the brake control device 18 detects an operation of the brake pedal 9, the brake control device 18 applies a braking force corresponding to the operation amount of the brake pedal 9 to each brake device 8. Further, the braking control device 18 of the present embodiment applies a braking force to one of the left and right front wheels 1FL and 1FR when an operation signal is input from an auxiliary steering control unit described later. However, even if an operation signal is input from an auxiliary steering control unit, which will be described later, the brake control circuit 6 detects a brake operation amount that is greater than a preset value by operating the brake pedal 9, and performs brake control according to the brake operation amount. Will be prioritized.

Further, as shown in FIG. 3, the left and right auxiliary wheels 12 are arranged apart from each other in the vehicle width direction in the space between the left and right rear wheels 1RL and 1RR. In the present embodiment, the case where the left auxiliary wheel 12 is arranged close to the left rear wheel 1RL and the right auxiliary wheel 12 is arranged close to the right rear wheel 1RR is illustrated.
The auxiliary wheel lifting / lowering device 13 is a device that supports each auxiliary wheel 12 at the rear part of the vehicle body so as to be movable up and down. The auxiliary wheel lifting / lowering device 13 of the present embodiment supports the auxiliary wheel 12 on the vehicle body by the links 26 to 28 so that the auxiliary wheel 12 can turn in the vehicle width direction, and drives the auxiliary wheel lift motor from the inner side in the vehicle width direction. The auxiliary wheel 12 is moved up and down by moving the auxiliary wheel 12 so as to go downward as it goes outward in the vehicle width direction. The auxiliary wheel lifting device 13 is provided for each auxiliary wheel 12.

Next, the auxiliary wheel lifting / lowering device 13 of this embodiment will be described with reference to FIG. FIG. 4 shows the auxiliary wheel elevating device 13 provided on the left rear wheel side as a representative. The configuration of the auxiliary wheel lifting device 13 on the right rear wheel side is the same.
Here, the rear wheels 1RL and 1RR constituting the third wheel are rotatably supported by the wheel support member 20. The wheel support member 20 is supported via a suspension device 24 so as to be swingable up and down with respect to the vehicle body. FIG. 4 shows an upper link 21, a lower link 22, and a shock absorber 23 as examples of suspension members that constitute the suspension device 24.

Further, the auxiliary wheel 12 is rotatably attached to the auxiliary wheel support member 25 as shown in FIG. The auxiliary wheel support member 25 and the wheel support member 20 are connected by a first link 26 so as to be swingable up and down. In addition, the auxiliary wheel support member 25 and the vehicle body are connected by the second and

third links

27 and 28 so as to be swingable up and down.
The second link 27 is composed of a lift motor, and the lift motor 27 has a drive shaft 27a that expands and contracts with respect to the motor body. The lift motor 27 is a linear motion device, and the motor main body 27b is connected to the vehicle body so as to be able to swing up and down. It is connected so that it can swing. That is, in the present embodiment, the second link 27 is configured by a lift motor, and the length of the second link is changed, so that the position of the auxiliary wheel support member side end portion of the second link is changed. Displace.

Here, the first link 26 is set such that the connection point to the wheel support member 20 is higher than the connection point to the auxiliary wheel support member 25. Further, the connection point of the third link 28 to the auxiliary wheel support member 25 is disposed below the connection point of the second link 27 to the auxiliary wheel support member 25. The first to third links 26 to 28 are preferably arranged on the same plane.
Moreover, since the auxiliary wheel 12 rolls in the vehicle width direction, it is preferable that the turning of the auxiliary wheel 12 at the time of the raising / lowering is set in the vehicle width direction. Of course, the link arrangement is set so that the turning of the auxiliary wheel 12 at the time of raising and lowering is in the vehicle front-rear direction other than the vehicle width direction.

As shown in FIG. 5, the auxiliary steering control unit 30 includes an auxiliary wheel lift processing unit 30A and a power difference distribution processing unit 30B.
When the auxiliary wheel lift processing unit 30 A detects that the auxiliary steering operation switch 19 is turned on, the auxiliary wheel lift processing unit 30 A supplies a lowering command to the lift motor control circuit 14. In addition, when the auxiliary wheel lift processing unit 30A detects that the auxiliary steering operation switch 19 is turned off, the auxiliary wheel lift processing unit 30A supplies a lift command to the lift motor control circuit 14. Here, the lift motor control circuit 14 drives the lift motor 27 by the lowering command, rotationally drives the link by a preset rotation angle so as to turn the auxiliary wheel 12 downward, and the auxiliary wheel 12 by the raising command. The lift motor 27 is driven so that the link turns by a preset rotation angle so as to turn upward.

In step S20, it is determined whether or not the vehicle is stopped. When it determines with the vehicle having stopped, it transfers to step S30. On the other hand, if it is determined that the vehicle is not stopped, the process proceeds to step S25.
Here, the vehicle stop determination may be performed, for example, as follows. That is, the vehicle speed is detected based on a signal from the wheel speed sensor 10, and the determination is made based on whether or not the detected vehicle speed is equal to or lower than a preset vehicle speed (for example, 5 Km / h) that can be regarded as the vehicle being stopped.

(Operation other)
The raising / lowering operation | movement of the said auxiliary wheel 12 is demonstrated with reference to FIG.
In the initial state, the auxiliary wheel elevating device 13 is in a state where the drive shaft 27a of the lift motor 27 is extended outward in the vehicle width direction. The extension of the drive shaft 27a causes the auxiliary wheel 12 to turn inward and upward in the vehicle width direction with the connection point P3 of the third link 28 to the auxiliary wheel support member 25 as the center of oscillation. The auxiliary wheel 12 is stored in the lower part of the vehicle body. As a result, as shown in FIG. 4B, the auxiliary wheel 12 is lifted and stored in the lower surface of the vehicle body.
At this time, the connection point P1 of the first link 26 to the auxiliary wheel support member 25 is located below the connection point P3 of the third link 28 to the auxiliary wheel support member 25. For this reason, with the extension of the drive shaft 27a, the first link 26 turns inward and upward in the vehicle width direction around the wheel side connection point, and the auxiliary wheel 12 further rises accordingly. It is in a state.

On the other hand, when the auxiliary steering operation switch 19 is turned “ON” and it is determined that the auxiliary wheel 12 is to be lowered, the lift motor 27 contracts the drive shaft 27a. When the drive shaft 27a contracts, as shown in FIG. 4A, the auxiliary wheel 12 is outward and downward in the vehicle width direction with the connection point P3 of the third link 28 to the auxiliary wheel support member 25 as the center of oscillation. Turn to head towards. As a result, the auxiliary wheel 12 descends and contacts the outer side in the vehicle width direction, and the auxiliary wheel 12 further descends to lift the rear part of the vehicle body.

After the auxiliary wheel 12 is in contact with the ground, the reaction force F from the ground is input to the wheel support member 20 through the first link 26, and as a result, the stroke amount of the rear wheels 1RL and 1RR is lowered. Can be kept small. When the vehicle body is lifted by the auxiliary wheel 12 in this way, the first link 26 connected to the auxiliary wheel support member 25 and the wheel support member 20 restricts the rear wheel from stroking in the rebound direction. The vehicle body can be lifted by the auxiliary wheel 12 while suppressing the stroke to the side.

Here, in a state where the vehicle body is lifted, the auxiliary wheel 12 is used so as to roll in the vehicle width direction. For this reason, in this embodiment, the turning direction of the auxiliary wheel 12 when moving up and down is set to turn in the rolling direction, that is, the vehicle width direction. Thereby, unnecessary wear of the auxiliary wheel 12 associated with the raising and lowering of the auxiliary wheel 12 can be suppressed.
In particular, in this embodiment, the connection point P1 of the first link 26 to the auxiliary wheel support member 25 is positioned below the connection point P3 of the third link 28 to the auxiliary wheel support member 25. For this reason, with the contraction of the drive shaft 27a, the first link 26 turns outward and downward in the vehicle width direction around the wheel side connection point, and the link of the first link 26 correspondingly. As the axis approaches the vertical direction, the force to suppress the rebound stroke of the rear wheel increases.
Here, the raising operation of the lowered auxiliary wheel 12 is the storing operation described above.

Next, with reference to FIG. 7, the state transition of the operation state of the auxiliary steering device accompanying the operation of the driver will be described.
The auxiliary steering device of the present embodiment starts to operate when the occupant operates the auxiliary steering operation switch 19 to ON.
In a normal travelable state, as shown in FIG. 4B, the auxiliary wheel 12 is stored on the vehicle body side and the auxiliary wheel 12 is in a non-grounded state. In this state, the driver moves the vehicle forward or backward by performing an accelerator operation.
When carrying out the auxiliary steering, the driver operates the brake to stop the vehicle, and puts the shift lever into the “N” or “P” range.

Subsequently, when the driver turns on the auxiliary steering operation switch 19, the auxiliary steering control unit 30 is activated, and the auxiliary steering control unit 30 lowers the left and right auxiliary wheels 12 to ground each auxiliary wheel 12. Lift the car body. As a result, the ground load of the rear wheels 1RL and 1RR is reduced to zero or small.
Subsequently, the auxiliary steering control unit 30 presents information indicating that auxiliary steering is possible after applying braking force to the right front wheel 1FR to lock the right front wheel 1FR.

When the driver confirms that auxiliary steering is possible, the driver selects whether to turn forward or backward by putting the shift lever into the “D” or “R” range.
Here, in the example of the auxiliary steering device of the present embodiment, since the braking force is applied to the right front wheel 1FR, it is possible to turn right in forward (D range) and turn left in backward (R range). Become.
In addition, when it is set as the structure which provides a braking force to the left front wheel 1FL, it will be in the state in which it can turn to the left by forward (D range), and to the right by reverse (R range).
Here, it is assumed that forward (D range) is selected.

In this state, when the driver steps on the accelerator pedal 5 to transmit the output of the engine 2 to the drive wheels 1FL, 1FR, the driving force is mainly distributed to the left front wheel 1FL side by the differential gear unit 3. As a result, a driving force difference is generated between the left and right front wheels 1FL and 1FR. Due to the difference in driving force between the left and right front wheels 1FL and 1FR, a moment in the yaw direction is generated with respect to the vehicle body. At this time, since the braking force is applied to the right front wheel 1FR among the left and right front wheels 1FL, 1FR, only the left front wheel 1FL rolls with the driving force. Thus, the vehicle turns right around the right front wheel 1FR to which the braking force is applied. At this time, the rear part of the vehicle body lifted by the auxiliary wheel 12 moves laterally to the left as the auxiliary wheel 12 rolls due to the force of the moment.
By such auxiliary steering, the vehicle moves in a small turn, thereby enabling parallel parking in a narrow place.
FIG. 8 shows an example of the turning state of the vehicle MM at that time. As shown in FIG. 8, the minimum turning radius is reduced by turning the vehicle MM around the right front wheel 1FR.

Furthermore, when the driver stops the accelerator operation and performs the brake operation, the turning operation of the vehicle is stopped.
Assume that the auxiliary steering operation switch 19 is changed to OFF after the vehicle stops and the driver puts the shift lever into the D range or the P range. Then, the auxiliary steering control unit 30 releases the braking force applied to the right front wheel 1FR and raises the auxiliary wheel 12 to store it on the vehicle body side. Thereafter, the auxiliary steering control unit 30 notifies the occupant of the cancellation of the auxiliary steering.
As described above, according to the auxiliary steering device of the present embodiment, the auxiliary wheel 12 is provided at the lower portion of the vehicle body, and the auxiliary wheel 12 is supported on the road surface by the lifting device, thereby lifting the rear wheel 1RL, 1RR releases the restraining force in the left-right direction with respect to the vehicle body.

In this state, when the driver selects the turning direction by the shift operation and then performs the accelerator operation, a driving force difference is generated between the left and right rear wheels 1RL and 1RR, and a moment in the yaw direction is generated in the vehicle body. At this time, since the braking force is applied to the right front wheel 1FR, the vehicle body can turn around the right front wheel 1FR to which the braking is applied or the vicinity thereof.
At this time, since the auxiliary wheel 12 is in a non-driving free state, the auxiliary wheel 12 rolls in the lateral direction of the vehicle body in a state in which the moment in the yaw direction generated in the vehicle body is not inhibited or small.
As a result, as the minimum turning radius of the vehicle becomes smaller than that in the normal state, the space required for parallel parking is extremely reduced as shown in FIG.
FIG. 10 shows an example of parking in the horizontal direction. In the example shown in FIG. 10, after the vehicle MM is moved forward to the front of the parking position, the vehicle MM is turned and moved forward to be parked at the target position.

Next, the operation when the auxiliary wheel 12 is stored in the lower surface of the vehicle body will be described.
FIG. 27 is a vehicle rear view schematically illustrating the behavior of the auxiliary wheel 12 and the links 26 to 28 when the rear wheel is bound and rebound.
Since the first to third links 26 to 28 are connected to each other so as to be swingable up and down, the first to third links 26 to 28 swing up and down following the bounding / rebounding of the wheels. Move. For this reason, as shown in FIG. 27, even when the suspension moves in the vertical direction in association with the bounding / rebounding of the wheel, the stored auxiliary wheel 12 follows the vertical direction without affecting the behavior of the suspension. Works.

In the present embodiment, a drive unit of a lift motor 27 that is a drive mechanism for raising and lowering the auxiliary wheel 12 is attached to the vehicle body side. For this reason, even if the auxiliary wheel 12 that moves up and down is set between the rear wheel and the vehicle body, an increase in unsprung weight can be reduced.
In addition, the suspension performance when riding over the protrusion is improved as compared with the case where the suspension is supported by the suspension for driving the auxiliary wheel 12 up and down.
FIG. 28 is a diagram showing a result of simulating the suspension performance.
This simulation is an evaluation of the acceleration on the rear wheel spring when the projection is passed over at a vehicle speed of 30 km / h. A solid line is a simulation result when the lifting device for the auxiliary wheel 12 according to the present embodiment is employed, and a broken line is a simulation result when the lifting device for the auxiliary wheel 12 described in Patent Document 1 is employed.

As can be seen from FIG. 28, when the lifting device for the auxiliary wheel 12 of the present embodiment is adopted, the acceleration on the rear wheel spring is small when the protrusion is passed at a vehicle speed of 30 km / h, and the riding comfort performance is improved. I understand that.
As described above, in the lifting device for the auxiliary wheel 12 according to the present embodiment, the auxiliary wheel 12 is provided in the lower part of the vehicle body, and the auxiliary wheel 12 is supported by the lifting device so as to be lifted and lowered. The auxiliary wheel 12 was supported on the vehicle body via a suspension of the vehicle. As a result, the vehicle body lifted by operating the drive mechanism is lifted together with the suspension, so that the lifting stroke of the lifting device is reduced and the device can be made compact.

In addition, the lifted vehicle body is supported by the auxiliary wheels 12 on the road surface via the suspension member, so that the suspension member acts in the same manner as in normal driving when the vehicle is driven by the auxiliary wheels 12. Will not be damaged. Even in the normal traveling state when the auxiliary wheel 12 is stored, the drive mechanism portion, which is a heavy component, is mounted on the vehicle body side, so that an increase in unsprung weight is suppressed, and the suspension performance when riding over the protrusion is improves.

(Modification)
(1) In the above embodiment, the wheel side end of the first link 26 is connected to the wheel support member. Alternatively, the wheel side end of the first link 26 may be connected to a suspension member such as a lower link.
(2) In the above embodiment, the drive mechanism that expands and contracts the length of the second link 27 is the lift motor 27 that linearly guides the drive shaft 27a by controlling the rotation of the electric motor. Alternatively, the drive mechanism may be configured with a fluid pressure cylinder device.

(3) Since the left and right rear wheels 1RL and 1RR are lifted by the auxiliary wheel 12 to reduce the ground load, the left and right rear wheels 1RL and 1RR may be driving wheels 1FL and 1FR or driven wheels.
(4) In the above description, the case where the left and right front wheels 1FL and 1FR are drive wheels is exemplified. When the left and right rear wheels 1RL and 1RR are drive wheels, the auxiliary wheel 12 may be disposed on the vehicle body front side.
In this case, for example, setting is made so that braking is applied to the right rear wheel 1RR side. An example of turning of the vehicle MM by auxiliary steering in this case is shown in FIG. In this case, for example, after the vehicle MM is retracted to the front of the parking position, the vehicle MM can be turned as shown in FIG.

(6) At this time, the auxiliary wheel 12 and the auxiliary wheel support member 25 may be connected via a rotary bearing to form a caster wheel. In this case, the rotation axis of the auxiliary wheel 12 is freely changed, so that the rotation axis is automatically adjusted to the center at the time of turning.
(7) In the above embodiment, the right driving wheel is described as a wheel to which braking is applied, but the wheel to which braking is applied may be set as the left driving wheel.
In the above description, driving wheels to which braking is applied are set in advance, but driving wheels to which braking is applied may be selected according to a driver's instruction. For example, the drive wheel to which braking is applied may be determined according to the steering direction of the steered wheel when the vehicle is stopped.

(8) In the above-described embodiment, a case where a driving force difference is generated between the left and right driving wheels by applying braking to one driving wheel and applying driving force to the other driving wheel is exemplified.
The configuration for generating a driving force difference between the left and right driving wheels is not limited to this. For example, the drive force difference may be generated by reversing the rotation directions of the left and right drive wheels. In this case, the vehicle body turns around the center position of the left and right drive wheels.
In addition, the driving force is transmitted to both the left and right driving wheels, but a driving force difference may be generated by changing the transmitted driving force.
Here, the lift motor 27 constitutes a drive mechanism.

(Effect of this embodiment)
This embodiment has the following effects.
(1) The first link 26 connects the auxiliary wheel support member 25 and the wheel support member or suspension member so as to be swingable up and down. The second link 27 connects the auxiliary wheel support member 25 and the vehicle body so as to be swingable up and down. The drive mechanism is supported by the vehicle body and displaces the position of the auxiliary wheel side end portion of the second link 27 in a direction approaching and separating from the wheel side end portion of the first link 26.
According to this configuration, an increase in unsprung weight can be suppressed by providing a drive mechanism for raising and lowering the auxiliary wheel 12 on the vehicle body side.

Furthermore, according to one aspect of the present invention, the wheel support member or suspension member and the vehicle body are connected via a link and an auxiliary wheel support member 25 connected in series. For this reason, the downward stroke (rebound) of the wheel support member can be suppressed or reduced by the force that operates the drive mechanism to displace the second link 27 or the force transmitted from the ground to the link. As a result, it is also possible to suppress an increase in the lifting stroke of the auxiliary wheel 12 due to lifting.

(2) At least in a state where the auxiliary wheel 12 is grounded, the connection point of the first link 26 to the wheel support member is set to a position higher than the connection point P1 of the first link 26 to the auxiliary wheel support member 25. To do.
According to this configuration, the downward stroke of the wheel can be more reliably suppressed by the reaction force F from the road surface input to the auxiliary wheel 12.
(3) The connection point P1 of the first link 26 to the auxiliary wheel support member 25 and the connection point P2 of the second link 27 to the auxiliary wheel support member 25 are arranged offset with respect to each other.
Furthermore, a third link 28 for connecting the auxiliary wheel support member 25 and the vehicle body is provided. The position of the connection point P3 of the third link 28 to the auxiliary wheel support member 25 is set to a position lower than the position of the connection point P2 of the second link 27 to the auxiliary wheel support member 25. .
According to the configuration of this link arrangement, the auxiliary wheel 12 can be reliably turned up and down.

(4) The drive mechanism is configured to extend and contract the second link 27. For example, the second link 27 is configured by a linear motion device.
Accordingly, the position of the auxiliary wheel side end portion of the second link 27 can be displaced in a direction approaching or separating from the wheel side end portion of the first link 26.

"2 of the third embodiment"
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
(Constitution)
As shown in FIG. 29, the basic configuration of the lifting device for the auxiliary wheel 12 of the present embodiment is the same as 1 of the third embodiment.
However, the relationship between the connection points P1 and P3 of the first link 26 and the third link 28 with respect to the auxiliary wheel support member 25 is different from 1 in the third embodiment. That is, the connection point P1 of the first link 26 to the auxiliary wheel support member 25 is set to a position higher than the position of the connection point P3 of the third link 28 to the auxiliary wheel support member 25.

As in 1 of the third embodiment, the position of the connection point P of the second link 27 to the auxiliary wheel support member 25 is the position of the connection point P of the third link 28 to the auxiliary wheel support member 25. In a higher position. Further, the connection point P of the second link 27 to the auxiliary wheel support member 25 is set lower than the position of the connection point P of the first link 26 to the auxiliary wheel support member 25.
Thus, the relative relationship of the connection point of each link to the auxiliary wheel support member 25 of the present embodiment is different from 1 of the third embodiment. Other configurations are the same as those of the third embodiment.

(Operation other)
The operation of the lifting device for the auxiliary wheel 12 will be described.
(When stored)
By contracting the drive shaft 27a of the lift motor 27, the connection point P3 of the third link 28 to the auxiliary wheel support member 25 with the connection point P1 of the first link 26 to the auxiliary wheel support member 25 as the center of oscillation. Turns outward and upward in the vehicle width direction. As a result, the auxiliary wheel 12 attached to the lower end of the auxiliary wheel support member 25 rises while turning outward in the vehicle width direction (wheel side), and the auxiliary wheel 12 enters the retracted state.

(Descent)
Assume that the auxiliary wheel 12 is stored.
In this state, by extending the drive shaft 27a of the lift motor 27, the auxiliary wheel support member 25 of the third link 28 with the connection point P1 of the first link 26 to the auxiliary wheel support member 25 as the center of swinging. The connection point P3 to the vehicle turns inward and downward in the vehicle width direction. As a result, the auxiliary wheel 12 descends and contacts the ground while turning inward in the vehicle width direction, and lifts the vehicle body by further descending.
Here, the raising operation of the auxiliary wheel 12 is the operation at the time of storage.
Here, the lift motor 27 constitutes a drive mechanism.

(Effect of this embodiment)
This embodiment has the following effect in addition to the effect of 1 of the said 3rd Embodiment.
(1) The lifting device 2 of the third embodiment has a configuration in which the auxiliary wheel 12 is lowered to lift the vehicle body by extending the linear motion shaft of the lift motor 27 constituting the linear motion device. .
For this reason, when the sliding accompanying expansion and contraction of the drive shaft 27a is taken into consideration, the structure is advantageous for buckling.

"3 of the third embodiment"
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
(Constitution)
The basic configuration of the lifting device for the auxiliary wheel 12 of this embodiment is the same as that of 1 of the third embodiment, as shown in FIG.
However, this embodiment differs from 1 and 2 in the third embodiment in that a drive mechanism that displaces the position of the auxiliary wheel side end of the second link 27 is employed.
That is, in 1 and 2 of the third embodiment, the position of the auxiliary wheel side end portion of the second link 27 is displaced by extending and retracting the drive shaft 27a with respect to the vehicle body. On the other hand, in this embodiment, the vehicle body side end of the second link 27 is displaced by the drive mechanism in the direction of approaching / separating from the wheel side, whereby the auxiliary wheel side end of the second link 27 is The position is displaced in a direction approaching / separating from the wheel side end of the first link 26.

The drive mechanism of this embodiment will be described.
The drive mechanism of the present embodiment is a linear motion device including a guide member 41a, a slide member 41b, and a drive unit 41c, and is fixed to the vehicle body.
The guide member 41a is fixed to the vehicle body in a state of extending in a direction toward the first link 26 in a plan view. The slide member 41b is movable along the guide member 41a. The movement of the slide member 41b may be a publicly known linear motion mechanism such as a ball screw mechanism or a linear guide mechanism that is realized by driving the drive unit 41c. The drive unit is usually constituted by a motor.

The wheel side end portion P4 of the second link 27 is attached to the slide member 41b so as to be swingable up and down.
Accordingly, the wheel side end portion of the second link 27 approaches and separates from the first link 26 by moving the position of the slide member 41b along the guide member 41a. As a result, the connection point P 2 of the second link 27 to the auxiliary wheel support member 25 is displaced so as to approach and separate from the first link 26. Thus, the same effect as 1 of the third embodiment can be obtained.
The arrangement configuration of the first to third links 26 to 28 may be the second configuration of the third embodiment.
Moreover, the linear motion apparatus provided with the guide member 41a, the slide member 41b, and the drive part 41c comprises a drive mechanism.

(Effect of this embodiment)
This embodiment has the following effect in addition to the effect of 1 of the said 3rd Embodiment.
(1) The drive mechanism displaces the wheel side connection point P4 of the second link 27. As a result, the position of the auxiliary wheel side end of the second link 27 can be displaced in the direction of approaching / separating from the wheel side end of the first link 26.
(2) In this embodiment, the vehicle body side end portion of the second link 27 is connected to the slide member 41b so as to be swingable.
For this reason, the linear motion mechanism attached to the vehicle body does not need to swing up and down. In particular, the drive unit of the linear motion device can be fixed to the vehicle body.
That is, the drive unit of the linear motion device, which is heavy and has a tendency to increase the installation space, is fixed to the vehicle body as a base. As a result, it is possible to minimize the influence of the drive unit being swung during normal travel in which the auxiliary wheels 12 are stored. In addition, the degree of freedom in layout increases.

“4 of the third embodiment”
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
(Constitution)
The basic configuration of the lifting device for the auxiliary wheel 12 of the present embodiment is the same as 1 of the third embodiment, as shown in FIG.
However, in the present embodiment, as shown in FIG. 31, the point of the slider portion constituting the second link 27 is fixed so as to be rotationally driven with respect to the vehicle body. And different.

That is, the drive device of the present embodiment is configured to rotate and drive to rotate the guide portion 27b of the slider portion 27 including the drive shaft 27a that expands and contracts and the cylindrical guide portion 27b that guides the drive shaft 27a. A driving unit 42, and the driving unit to be driven is fixed to the vehicle body.
The other configuration is the same as 1 in the third embodiment.
Here, the arrangement of the first to third links 26 to 28 may be the same arrangement as 2 in the third embodiment. In this case, the same effect as 2 of the third embodiment can be obtained.

(Operation etc.)
The expansion and contraction of the drive shaft 27a accompanying the raising and lowering of the wheel is the same operation as 1 in the third embodiment. However, this embodiment is different from 1 of the third embodiment in that the bottom of the slider portion 27 on which the drive shaft 27a expands and contracts is forcibly rotated by the rotation drive portion 41.
That is, when extending the drive shaft 27 a to store the auxiliary wheel 12, the auxiliary wheel 12 is raised by turning the slider portion 27 upward by the rotary drive unit 42. Further, when the drive shaft 27 a is contracted to lower the auxiliary wheel 12, the auxiliary wheel 12 is lowered by turning the slider portion 27 downward by the rotary drive unit 42.

In the present embodiment, the rotation driving unit 42 can arbitrarily adjust the vertical inclination of the second link 27. For this reason, for example, compared with 1 of 3rd Embodiment, the 2nd link 27 can be turned up and the auxiliary wheel 12 can be stored up by that much.
Note that, during normal traveling with the auxiliary wheel 12 stored, at least the auxiliary wheel support member 25 and the wheel support member 20 are connected by the first link 26 so as to be swingable up and down. For this reason, it is possible to reduce an adverse effect on the behavior of the suspension at the time of bounce / rebound of the vehicle during normal driving.
Here, the lift motor 27 constitutes a drive mechanism.

(Effect of this embodiment)
This embodiment has the following effect in addition to the effect of 1 of the said 3rd Embodiment.
(1) In the drive mechanism of the present embodiment, the drive unit, which is a heavy component requiring space, is fixed to the base vehicle body. For this reason, during normal travel in which the auxiliary wheels 12 are stored, the swing of the direct drive section of the drive mechanism is suppressed, and the influence of the drive mechanism being swung can be minimized.

[Fourth Embodiment]
Next, embodiments of the present invention will be described with reference to the drawings.
"1 of the fourth embodiment"
(Constitution)
FIG. 1 is a schematic diagram showing a configuration of a vehicle according to the present embodiment, and FIG. 2 is a system diagram thereof.
In the present embodiment, as shown in FIG. 1, a vehicle having left and right front wheels 1FL and 1FR and left and right rear wheels 1RL and 1RR and using left and right front wheels 1FL and 1FR as driving wheels will be described as an example. In the present invention, the steering wheel is not particularly limited.

Further, as shown in FIG. 3, the left and right auxiliary wheels 12 are arranged apart from each other in the vehicle width direction in the space between the left and right rear wheels 1RL and 1RR. In the present embodiment, the case where the left auxiliary wheel 12 is arranged close to the left rear wheel 1RL and the right auxiliary wheel 12 is arranged close to the right rear wheel 1RR is illustrated.
The auxiliary wheel lifting / lowering device 13 is a device that supports each auxiliary wheel 12 at the rear part of the vehicle body so as to be movable up and down. As shown in FIGS. 32 and 33, the auxiliary wheel elevating device 13 of this embodiment supports each auxiliary wheel 12 on the vehicle body so as to be turnable in the vehicle width direction by individual links 26 to 28, and has a common approach / By driving the separation mechanism with the motor 37, the left and right auxiliary wheels 12 are turned and moved downward from the inner side in the vehicle width direction toward the outer side in the vehicle width direction. Thus, the auxiliary wheel 12 is raised and lowered.

Next, the auxiliary wheel lifting / lowering device 13 of this embodiment will be described with reference to FIGS. 32 and 33.
Here, the left and right rear wheels 1RL, 1RR constituting the third wheel are rotatably supported by the wheel support member 20, respectively, as shown in FIGS. The left and right wheel support members 20 are supported to be swingable up and down with respect to the vehicle body 57 via individual suspension devices 24. 32 and 33, an upper link 21, a lower link 22, and a shock absorber 23 are illustrated as an example of a suspension member constituting the suspension device 24.
As shown in FIGS. 32 and 33, the auxiliary wheel lifting device supports left and right auxiliary wheel support members 25 that make the left and right auxiliary wheels 12 rotatable, and left and right auxiliary wheel support members 25 supported by a vehicle body 57, respectively. And an approach / separation mechanism that drives the left and right auxiliary wheels 12 to move up and down in synchronization.

Further, the configuration of the auxiliary wheel lifting device will be described.
As shown in FIGS. 32 and 33, the left and right auxiliary wheels 12 are rotatably supported by the left and right auxiliary wheel support members 25, respectively. Each auxiliary wheel support member 25 is suspended between the wheel and the vehicle body by an auxiliary wheel link mechanism. Each of the left and right auxiliary wheel link mechanisms includes first to third links 25 to 28, as shown in FIGS. The first link 26 connects the corresponding auxiliary wheel support member 25 and the wheel support member 20 in a state in which the first link 26 can swing up and down. The second and

third links

27 and 28 are connected so that the auxiliary wheel support member 25 and the vehicle body 57 can swing up and down.

Here, the first link 26 is set such that the connection point to the wheel support member 20 is higher than the connection point to the auxiliary wheel support member 25. Further, the connection point of the third link 28 to the auxiliary wheel support member 25 is disposed below the connection point of the second link 27 to the auxiliary wheel support member 25. Here, the mutual relationship of the connection points of the first to third links 25 to 28 to the auxiliary wheel support member 25 is not limited to the above arrangement. The auxiliary wheel 12 only needs to be configured to be able to move up and down by the displacement of the second link 27. The first to third links 26 to 28 constituting the auxiliary wheel link mechanism are preferably arranged on the same plane.

The approach / separation mechanism of the present embodiment is a ball screw mechanism. That is, the approach / separation mechanism includes a screw shaft 35 and a pair of nuts 36 R and 36 L that are screwed onto the screw shaft 35. The drive unit includes a motor 37 that rotationally drives the screw shaft 35.
The screw shaft 35 extends in the vehicle width direction and is attached to the vehicle body 57 in a rotatable state. The screw shaft 35 has a right screw portion 35b extending to the right side and a left screw portion 35a extending to the left side with respect to the axial central portion, and the screw directions of the right screw portion 35b and the left screw portion 35a are reversed.

Nuts

36R and 36L are screwed into the right and

left screw portions

35b and 35a, respectively, which are set in the directions. As a result, the left and

right nuts

36R, 36L linearly move in the direction in which the left and

right nuts

36R, 36L approach and separate from each other as the screw shaft 35 rotates. And the vehicle body side edge part of the 2nd link located in the right side with respect to the nut 36R screwed together with the said right side screw part 35b is connected so that rocking | fluctuation is possible. Further, the vehicle body side end portion of the second link 27 located on the left side is connected to the nut 36L screwed to the left side screw portion 35a so as to be vertically swingable.

The output shaft of the motor 37 is connected to the screw shaft 35 via a gear. The motor 37 is fixed to the vehicle body 57.
According to the above configuration, the rotational torque of the motor 37 is transmitted to the screw shaft 35, and the left and right nuts 36 R and 36 L approach and separate as the screw shaft 35 rotates. When the left and

right nuts

36R, 36L approach / separate, the vehicle body side end portions of the left / right second links 27 approach / separate. Then, as the distance between the vehicle body side ends of the left and right second links 27 increases, the auxiliary wheel 12 rises and the auxiliary wheel 12 enters the retracted state, as shown in FIG. Conversely, as the distance between the vehicle body side ends of the left and right second links 27 approaches, the auxiliary wheel 12 descends and the vehicle body 57 is lifted, as shown in FIG.
Here, since the auxiliary wheel 12 rolls in the vehicle width direction, it is preferable to set the turning direction of the auxiliary wheel 12 in the vehicle width direction at the time of raising and lowering. Of course, the link arrangement is set so that the turning of the auxiliary wheel 12 at the time of raising and lowering is in the vehicle front-rear direction other than the vehicle width direction.

The lift motor control circuit 14 reads the motor position and current value from the motor 37 that raises and lowers the auxiliary wheel 12 and controls the position of the motor 37.
As shown in FIG. 5, the auxiliary steering control unit 30 is configured as a part of a program of the controller 15 that performs vehicle control. Here, the controller 15 is constituted by a CPU, a ROM, a RAM, and the like, and programs for realizing various processes are stored in the ROM. The controller 15 reads the driver's operation switch, the shift position by the shift operation, and the rotational speed of the wheel by the wheel speed sensor 10. Then, the controller 15 determines the vehicle state based on the signal from the sensor or the like, and communicates with the brake control circuit 6 for controlling the braking force, the lift motor control circuit 14 for raising and lowering the auxiliary wheel 12 and the like through the interface circuit. Command is possible.

As shown in FIG. 5, the auxiliary steering control unit 30 includes an auxiliary wheel lift processing unit 30A and a power difference distribution processing unit 30B.
When the auxiliary wheel lift processing unit 30 A detects that the auxiliary steering operation switch 19 is turned on, the auxiliary wheel lift processing unit 30 A supplies a lowering command to the lift motor control circuit 14. In addition, when the auxiliary wheel lift processing unit 30A detects that the auxiliary steering operation switch 19 is turned off, the auxiliary wheel lift processing unit 30A supplies a lift command to the lift motor control circuit 14. Here, the lift motor control circuit 14 drives the motor 37 by the lowering command, rotationally drives the link by a preset rotation angle so as to turn the auxiliary wheel 12 downward, and the auxiliary wheel 12 is driven by the raising command. The motor 37 is driven so that the link turns by a preset rotation angle so as to turn upward.

In step S25, the driver is notified that the brake operation is urged. Thereafter, the process proceeds to step S10.
In step S30, it is determined whether or not the auxiliary steering operation switch 19 has been turned ON. If it is determined that the operation has been turned ON, the process proceeds to step S30. If it is determined that the auxiliary steering operation switch 19 is turned off, the process proceeds to step S100.
In step S 40, the auxiliary wheel lift processing unit 30 A performs control to lower the auxiliary wheel 12 and to ground it. In the present embodiment, a lowering command is supplied to each motor 37. As a result, the rear part of the vehicle body is lifted. And the ground load on the rear wheels 1RL, 1RR is reduced.

On the other hand, when the auxiliary steering operation switch 19 is turned off and the process proceeds to step S100, the power difference distribution processing unit 30B performs a process of releasing the braking force applied to the right front wheel 1FR.
Next, in step S110, the auxiliary wheel lift processing unit 30A performs a process of raising the auxiliary wheel 12 and storing it. In the present embodiment, a rising command is supplied to each motor 37.
Next, in step S120, when it is detected that the storage of the auxiliary wheel 12 has been completed and the release of the braking force to the right front wheel 1FR has been completed, an information presentation to the effect that the auxiliary steering process has been canceled is notified to the occupant. The notification is displayed on a display unit or the like of a navigation device that can be visually recognized by an occupant, or is performed by voice.
Thereafter, the process ends.

(Operation other)
The raising / lowering operation | movement of the said auxiliary | assistant wheel 12 is demonstrated with reference to FIG.32 and FIG.33.
In the initial state, the auxiliary wheel elevating device 13 is in a state in which the left and

right nuts

36R and 36L are separated from each other as shown in FIG. By separating the left and

right nuts

36R, 36L, the vehicle body side ends of the left and right second links 27 are synchronized and displaced outward in the vehicle width direction. As a result, the auxiliary wheel 12 turns inward and upward in the vehicle width direction with the connection point of the third link 28 to the auxiliary wheel support member 25 as the center of oscillation, and the auxiliary wheel 12 It is in the state stored in. That is, as shown in FIG. 32, the auxiliary wheel 12 is raised and stored in the lower surface of the vehicle body.

At this time, the connection point of the first link 26 to the auxiliary wheel support member 25 is located below the connection point of the third link 28 to the auxiliary wheel support member 25. For this reason, as the left and right second links 27 move in synchronization with the vehicle body side ends, the first links 26 are inward in the vehicle width direction around the wheel side connection points. The vehicle turns in the upward direction, and the auxiliary wheel 12 is further raised accordingly.

On the other hand, when the auxiliary steering operation switch 19 is turned “ON” and it is determined that the auxiliary wheel 12 is to be lowered, the motor 37 is rotationally driven to bring the left and

right nuts

36R and 36L closer to each other. When the left and

right nuts

36R and 36L approach each other, the left and right second links 27 are displaced in the vehicle width direction center side in synchronization with each other, as shown in FIG. The vehicle pivots outward and downward in the vehicle width direction with the connection point of the link 28 to the auxiliary wheel support member 25 as the swing center. As a result, the auxiliary wheel 12 descends and grounds while facing outward in the vehicle width direction, and the auxiliary wheel 12 further descends and lifts the rear part of the vehicle body.

After the auxiliary wheel 12 is in contact with the ground, a reaction force from the ground is input to the wheel support member 20 through the first link 26. As a result, the downward stroke amount of the rear wheels 1RL and 1RR is increased. Can be kept small. When the vehicle body 57 is lifted by the auxiliary wheel 12 in this way, the first wheel 26 connected to the auxiliary wheel support member 25 and the wheel support member 20 is used to restrict the rear wheels 1RL and 1RR from moving in the rebound direction. The vehicle body 57 can be lifted by the auxiliary wheels 12 while suppressing the downward stroke of the rear wheels 1RL and 1RR.

Here, in a state where the vehicle body 57 is lifted, the auxiliary wheel 12 is used so as to roll in the vehicle width direction. For this reason, in this embodiment, the turning direction of the auxiliary wheel 12 when moving up and down is set to turn in the rolling direction, that is, the vehicle width direction. Thereby, unnecessary wear of the auxiliary wheel 12 associated with the raising and lowering of the auxiliary wheel 12 can be suppressed.
In particular, in this embodiment, the connection point of the first link 26 to the auxiliary wheel support member 25 is positioned below the connection point of the third link 28 to the auxiliary wheel support member 25. For this reason, with the movement of the left and right second links 27, the first link 26 turns outward and downward in the vehicle width direction around the wheel side connection point, and accordingly, the first link 26 The link axis of the link 26 approaches the vertical direction, and the force for suppressing the rebound stroke of the rear wheels 1RL and 1RR increases.

In the present embodiment, the left and right auxiliary wheels 12 separated in the vehicle width direction are synchronized, and the rear part of the vehicle body is lifted by a mechanical link mechanism. For this reason, even when shifting to auxiliary steering on an inclined road surface, the rear part of the vehicle body can be lifted upward in parallel with the road surface. That is, the wobbling of the rear part of the vehicle body to the left and right can be suppressed to be small, so that the vehicle body can be lifted stably.
Here, the raising operation of the lowered auxiliary wheel 12 is the storing operation described above.

Next, with reference to FIG. 7, the state transition of the operation state of the auxiliary steering device accompanying the operation of the driver will be described.
The auxiliary steering device of the present embodiment starts to operate when the occupant operates the auxiliary steering operation switch 19 to ON.
In the normal travelable state, as shown in FIG. 32, the auxiliary wheel 12 is stored on the vehicle body 57 side, and the auxiliary wheel 12 is in a non-grounded state. In this state, the driver moves the vehicle forward or backward by performing an accelerator operation.
When carrying out the auxiliary steering, the driver operates the brake to stop the vehicle, and puts the shift lever into the “N” or “P” range.

Subsequently, when the driver turns on the auxiliary steering operation switch 19, the auxiliary steering control unit 30 is activated, and the auxiliary steering control unit 30 is lowered to lower the left and right auxiliary wheels 12 to ground each auxiliary wheel 12. Then, as shown in FIG. 33, the vehicle body 57 is continuously lifted. As a result, the ground load of the rear wheels 1RL and 1RR is reduced to zero or small.
Subsequently, the auxiliary steering control unit 30 presents information indicating that auxiliary steering is possible after applying braking force to the right front wheel 1FR to lock the right front wheel 1FR.

Here, it is assumed that forward (D range) is selected.
In this state, when the driver steps on the accelerator pedal 5 to transmit the output of the engine 2 to the drive wheels 1FL, 1FR, the driving force is mainly distributed to the left front wheel 1FL side by the differential gear unit 3. As a result, a driving force difference is generated between the left and right front wheels 1FL and 1FR. Due to the difference in driving force between the left and right front wheels 1FL and 1FR, a moment in the yaw direction is generated with respect to the vehicle body 57. At this time, since the braking force is applied to the right front wheel 1FR among the left and right front wheels 1FL, 1FR, only the left front wheel 1FL rolls with the driving force. Thus, the vehicle turns right around the right front wheel 1FR to which the braking force is applied. At this time, the rear part of the vehicle body lifted by the auxiliary wheel 12 moves laterally to the left as the auxiliary wheel 12 rolls due to the force of the moment.

By such auxiliary steering, the vehicle moves in a small turn, thereby enabling parallel parking in a narrow place.
FIG. 8 shows an example of the turning state of the vehicle MM at that time. As shown in FIG. 8, the minimum turning radius is reduced by turning the vehicle MM around the right front wheel 1FR.
Furthermore, when the driver stops the accelerator operation and performs the brake operation, the turning operation of the vehicle is stopped.
Assume that the auxiliary steering operation switch 19 is changed to OFF after the vehicle stops and the driver puts the shift lever into the D range or the P range. Then, the auxiliary steering control unit 30 releases the application of the braking force to the right front wheel 1FR and raises the auxiliary wheel 12 to store it on the vehicle body 57 side. Thereafter, the auxiliary steering control unit 30 notifies the occupant of the cancellation of the auxiliary steering.

As described above, according to the auxiliary steering device of the present embodiment, the auxiliary wheel 12 is provided at the lower portion of the vehicle body 57, and the auxiliary wheel 12 is supported on the road surface by the lifting device, whereby the rear wheel 1RL lifted up. 1RR releases the restraining force in the left-right direction with respect to the vehicle body 57.
In this state, when the driver selects the turning direction by the shift operation and then performs the accelerator operation, a driving force difference is generated between the left and right rear wheels 1RL and 1RR, and a moment in the yaw direction is generated in the vehicle body 57. At this time, since the braking force is applied to the right front wheel 1FR, the vehicle body 57 can turn around the right front wheel 1FR to which the braking is applied or its vicinity.

At this time, since the auxiliary wheel 12 is in a non-driving free state, the auxiliary wheel 12 rolls in the lateral direction of the vehicle body in a state in which the moment in the yaw direction generated in the vehicle body 57 is not inhibited or small.
As a result, as the minimum turning radius of the vehicle becomes smaller than that in the normal state, the space required for parallel parking is extremely reduced as shown in FIG.
FIG. 10 shows an example of parking in the horizontal direction. In the example shown in FIG. 10, after the vehicle MM is moved forward to the front of the parking position, the vehicle MM is turned and moved forward to be parked at the target position.

Next, the operation when the auxiliary wheel 12 is stored in the lower surface of the vehicle body will be described.
FIG. 27 is a vehicle rear view schematically showing the behavior of the auxiliary wheel 12 and the links 26 to 28 when the rear wheels 1RL and 1RR are bound and rebound.
Since the first to third links 26 to 28 are connected to each other so as to be swingable up and down, the first to third links 26 to 28 swing up and down following the bounding / rebounding of the wheels. Move. For this reason, as shown in FIG. 27, even when the suspension moves in the vertical direction in association with the bounding / rebounding of the wheel, the stored auxiliary wheel 12 follows the vertical direction without affecting the behavior of the suspension. Works.

Further, in the present embodiment, a motor 37 that is a drive unit for raising and lowering the auxiliary wheel 12 is attached to the vehicle body 57. For this reason, even if the auxiliary wheel 12 that moves up and down is set between the rear wheels 1RL and 1RR and the vehicle body 57, an increase in unsprung weight can be reduced.
Then, the suspension performance when riding over the protrusion is improved as compared with the case where the approach / separation mechanism for raising and lowering the auxiliary wheel 12 is supported only by the suspension.
FIG. 28 is a diagram showing a result of simulating the suspension performance.
This simulation is an evaluation of the acceleration on the rear wheel spring when the projection is passed over at a vehicle speed of 30 km / h. A solid line is a simulation result when the lifting device for the auxiliary wheel 12 according to the present embodiment is employed, and a broken line is a simulation result when the lifting device for the auxiliary wheel 12 described in Patent Document 1 is employed.
As can be seen from FIG. 28, when the lifting device for the auxiliary wheel 12 of the present embodiment is adopted, the acceleration on the rear wheel spring is small when the protrusion is passed at a vehicle speed of 30 km / h, and the riding comfort performance is improved. I understand that.

As described above, in the lifting device for the auxiliary wheel 12 according to the present embodiment, the auxiliary wheel 12 is provided at the lower portion of the vehicle body 57 and the auxiliary wheel 12 is supported by the lifting device so as to be lifted and lowered. The auxiliary wheel 12 was supported by the vehicle body 57 via a suspension of the vehicle. As a result, the vehicle body 57 lifted by operating the approach / separation mechanism is lifted together with the suspension, so that the lifting stroke of the lifting device is reduced and the device can be made compact.

Further, the lifted vehicle body 57 is supported by the auxiliary wheel 12 on the road surface via the suspension member, so that the suspension member acts when the vehicle is driven by the auxiliary wheel 12 in the same manner as in normal driving. There is no loss of comfort. Even in the normal running state when the auxiliary wheels 12 are stored, the driving part, which is a heavy component, is mounted on the vehicle body 57 side, so that an increase in unsprung weight is suppressed, and the suspension performance when riding over the protrusion is improves.

(Modification)
(1) In the above embodiment, the wheel side end of the first link 26 is connected to the wheel support member. Alternatively, the wheel side end of the first link 26 may be connected to a suspension member such as a lower link.
(2) Since the left and right rear wheels 1RL, 1RR are lifted by the auxiliary wheel 12 to reduce the ground load, the left and right rear wheels 1RL, 1RR may be drive wheels 1FL, 1FR or driven wheels.
(3) In the above description, the left and right front wheels 1FL and 1FR are illustrated as driving wheels. When the left and right rear wheels 1RL and 1RR are drive wheels, the auxiliary wheel 12 may be disposed on the vehicle body front side.
In this case, for example, setting is made so that braking is applied to the right rear wheel 1RR side. An example of turning of the vehicle MM by auxiliary steering in this case is shown in FIG. In this case, for example, after the vehicle MM is retracted to the front of the parking position, the vehicle MM can be turned as shown in FIG.

(4) Here, the rotation shafts of the left and right auxiliary wheels 12 are arranged to face in the vehicle front-rear direction so that the auxiliary wheels 12 roll in the vehicle lateral direction during auxiliary steering.
However, in the present embodiment, since the vehicle body 57 rotates around the right front wheel 1FR, the rotation shaft of the auxiliary wheel 12 may be set to face the right front wheel 1FR as shown in FIG. preferable. In this way, the auxiliary wheel 12 is more easily rolled by directing the rotation shaft to the center at the time of turning. In FIG. 13, symbol L indicates an extension line of the rotation shaft of the auxiliary wheel 12.

(5) At this time, the auxiliary wheel 12 and the auxiliary wheel support member 25 may be coupled via a rotary bearing to form a caster wheel. In this case, the rotation axis of the auxiliary wheel 12 is freely changed, so that the rotation axis is automatically adjusted to the center at the time of turning.
(6) In the above embodiment, the right driving wheel is described as a wheel to which braking is applied, but the wheel to which braking is applied may be set as the left driving wheel.
In the above description, driving wheels to which braking is applied are set in advance, but driving wheels to which braking is applied may be selected according to a driver's instruction. For example, the drive wheel to which braking is applied may be determined according to the steering direction of the steered wheel when the vehicle is stopped.

(7) In the above-described embodiment, an example is given in which a driving force difference is generated between the left and right driving wheels by applying braking to one driving wheel and applying driving force to the other driving wheel.
The configuration for generating a driving force difference between the left and right driving wheels is not limited to this. For example, the drive force difference may be generated by reversing the rotation directions of the left and right drive wheels. In this case, the vehicle body 57 rotates around the center position of the left and right drive wheels.
In addition, the driving force is transmitted to both the left and right driving wheels, but a driving force difference may be generated by changing the transmitted driving force.
The screw shaft 35 and the nuts 36R and 36L constitute an approach / separation mechanism. The motor 37 constitutes a drive unit.

(Effect of this embodiment)
This embodiment has the following effects.
(1) In each of the left and right auxiliary wheels 12, an auxiliary wheel support member 25 that rotatably supports the auxiliary wheel 12 is connected to a wheel support member or a suspension member via a first link so as to be vertically swingable. At the same time, the vehicle body 57 is connected to the vehicle body 57 through the second link 27 so as to be swingable up and down. The approach / separation mechanism approaches / separates the vehicle body side end portions of the left and right second links 27. The drive unit is attached to the vehicle body 57 and drives the approach / separation mechanism.

According to this configuration, it is possible to suppress an increase in unsprung weight by providing the driving unit for raising and lowering the auxiliary wheel 12 on the vehicle body 57 side. In this embodiment, since the approach / separation mechanism and the drive unit for driving the left and right auxiliary wheels 12 are common, the left and right auxiliary wheels 12 can be moved up and down in synchronization.
Further, the wheel support member or suspension member and the vehicle body 57 are connected via a link and an auxiliary wheel support member 25 connected in series. For this reason, the downward stroke (rebound) of the wheel support member can be suppressed or reduced by the force transmitted from the ground to the link. As a result, it is also possible to suppress an increase in the lifting stroke of the auxiliary wheel 12 due to lifting.

(2) The approach / separation mechanism is a ball screw mechanism including a screw shaft 35 extending in the vehicle width direction and a pair of

nuts

36R and 36L screwed to the screw shaft 35. The drive unit is a motor 37 that rotationally drives the screw shaft 35. The screw shaft 35 has a right screw portion 35b extending to the right side and a left screw portion 35a extending to the left side, and the screw directions of the right screw portion 35b and the left screw portion 35a are set in opposite directions, and

Nuts

36R and 36L are screwed into the right screw portion 35b and the left screw portion 35a, respectively. The vehicle body side end portion of the second link 27 located on the right side is connected to the nut 36R screwed into the right screw portion 35b, and the second link located on the left side of the nut 36L screwed into the left screw portion 35a. 27 end portions on the vehicle body side are connected.
By adopting this configuration, the left and right auxiliary wheels 12 can be moved up and down in synchronization.
Further, since the ball screw mechanism constituting the approach / separation mechanism is arranged along the vehicle width direction, the space required in the vertical direction for arranging the approach / separation mechanism can be reduced.

"2 of the fourth embodiment"
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
(Constitution)
The basic configuration of the lifting device for the auxiliary wheel 12 of the present embodiment is the same as 1 of the fourth embodiment. However, as shown in FIGS. 34 and 35, this is an example in which two

motors

37R and 37L are provided as drive units for transmitting rotational torque to the screw shaft 35. Each

motor

37R, 37L is individually attached to the vehicle body 57. The

motors

37R and 37L can transmit torque to the screw shaft 35 via individual gears.

That is, this embodiment is an example in which two drive

units

37R and 37L are provided for one approach / separation mechanism. There may be three or more motors as drive units.
Here, when the auxiliary wheel 12 is operated, that is, when the vehicle body 57 is lifted, a relatively large output is required. However, when the auxiliary wheel 12 is stored, there is no problem even if the auxiliary wheel 12 is stored.
In view of this, in this embodiment, when using two

small motors

37R and 37L whose output is smaller than that of the motor 37 used in 1 of the fourth embodiment, the auxiliary wheel 12 is lowered and the vehicle body 57 is lifted. When the two

motors

37R and 37L are driven in cooperation and the auxiliary wheel 12 is raised and stored, two units are set so that only one of the two

motors

37R and 37L is driven. It becomes possible to drive the

motors

37R and 37L. In this case, power consumption is reduced.

At this time, even if the motor 37R side that is driven when storing the auxiliary wheel 12 breaks down and a failure state is reached, the auxiliary wheel 12 can be stored by driving the other motor 37L side. Thus, even if the motor 37R used mainly breaks down, the auxiliary wheel 12 does not prevent the vehicle from traveling normally (self-propelled).
Other configurations, operations, and the like are the same as those of the first embodiment.
Here, the screw shaft 35 and the nut 36R. 36L constitutes an approach / separation mechanism. Each of the

motors

37R and 37L constitutes a drive unit.

(Effect of this embodiment)
In addition to the effect of 1 of the said 4th Embodiment, this embodiment has the following effect.
(1) The auxiliary wheel lifting device includes one approach / separation mechanism and two or more drive units that drive the approach / separation mechanism. And when raising the auxiliary wheel 12, one drive part of two or more drive parts drives an approach and separation mechanism.
According to this configuration, even if the drive unit that raises the auxiliary wheel 12 fails, the auxiliary wheel 12 can be raised and stored by another drive unit.

“3 of the fourth embodiment”
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
(Constitution)
The basic configuration of the lifting device for the auxiliary wheel 12 of this embodiment is the same as 1 and 2 of the fourth embodiment.
However, in the present embodiment, the third link 28 is omitted. However, the third link 28 may be provided.

In this embodiment, as shown in FIG. 36, the approach / separation mechanism includes a pantograph-like link structure in which four links (arms 40 to 44) are arranged in a parallelogram shape, and an approach / separation mechanism main body. It comprised with the screw rod 47 to comprise.
This approach / separation mechanism is the same mechanism as the pantograph jack mechanism. That is, the pantograph jack device is attached to the vehicle body 57 and the pantograph jack device is driven by the

motors

37R and 37L, thereby lifting the vehicle body 57 through the second link 27 and the auxiliary wheel 12.
The pantograph-like link structure includes two

right arms

43 and 44, two

left arms

40 and 41, a first connecting portion 45, and a second connecting portion 46.

The two

right arms

43 and 44 extend to the left second link 27 side by connecting the outer end to the vehicle body side end of the right second link 27, respectively. The two left arms extend to the right second link 27 side by connecting the outer end to the vehicle body side end of the left second link 27. The first connecting portion 45 connects the inner end portion of the upper right arm 43 and the inner end portion of the upper left arm 40. The second connecting portion 46 connects the inner end portion of the lower right arm 44 and the inner end portion of the lower left arm 41.

The first connecting portion 45 is provided with a cylindrical member (not shown) having an internal thread formed on the inner diameter surface. Then, the lower end side of the screw rod 47 is supported with respect to the second connecting portion 46 in a state where the shaft rotation is free and the movement in the axial direction is restricted, and the upper side of the screw rod 47 is screwed into the cylindrical member. The first screw portion is configured, and the two connecting

portions

45 and 46 are moved closer to and away from each other by the screw motion at the first screw portion.

And two

motors

37R and 37L which comprise a drive part are connected with respect to the upper-end part of the said screw rod 47 via a separate gearwheel.
As described above, this embodiment is an example in which two

motors

37R and 37L are provided as drive units that rotationally drive the screw rods 47 constituting the approach / separation mechanism main body. Each

motor

37R, 37L is individually attached to the vehicle body 57. That is, this embodiment is an example in which two drive units are provided for one approach / separation mechanism. There may be three or

more motors

37R, 37L as drive units.

In the present embodiment, the screw rod 47 is rotationally displaced to increase the distance between the two connecting

portions

45 and 46, so that the inner ends of the left and right second links 27 approach each other in synchronization. By reducing the distance between the two connecting

portions

45 and 46, the inner end portions of the left and right second links 27 are separated in synchronization.
Other configurations and operations are the same as those in 2 of the fourth embodiment.
Here, the screw rod 47 constitutes a screw shaft (an approach / separation mechanism main body).

(Effect of this embodiment)
In addition to the effect of 1 of the said 4th Embodiment, this embodiment has the following effect.
(1) The approach / separation mechanism includes a pantograph-like link structure and an approach / separation mechanism main body that approaches / separates between the first connection part 45 and the second connection part 46 of the link structure. The driving unit drives the approach / separation mechanism main body.
By adopting this configuration, the inner ends of the left and right second links 27 can be approached and separated.

(2) The approach / separation mechanism main body includes a screw rod 47 that connects the first connecting portion 45 and the second connecting portion 46. The drive unit rotates and drives the screw rod 47 to approach and separate the first connection part 45 and the second connection part 46.
According to this configuration, it is possible to change the link structure while ensuring the rigidity of the pantograph-like link structure.

"4 of the fourth embodiment"
Next, another embodiment will be described with reference to the drawings. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
(Constitution)
The basic configuration of the lifting device for the auxiliary wheel 12 of the present embodiment is the same as 3 of the fourth embodiment. However, the approach / separation mechanism of the present embodiment comprises a pantograph-like link structure in which four links (arms 40 to 44) are arranged in a parallelogram shape and an approach / separation mechanism main body as shown in FIG. The linear motion device 50 is configured.
The pantograph-like link structure of the present embodiment is the same as the pantograph-like link structure 3 of the fourth embodiment.

The approach / separation mechanism main body is a linear motion device 50 including a ball screw mechanism or a linear guide that converts the rotational motion of the rotating component 51 into a linear motion. The linear motion device 50 is configured to approach / separate between the first connecting portion 45 and the second connecting portion 46 in accordance with the rotational displacement of the rotating component 51.
The rotating component 51 is rotatably supported on the vehicle body 57.
As the drive unit of this embodiment, two

motors

37R and 37L are provided. The output shafts of the

motors

37R and 37L are connected to the rotating component 51 by an endless annular belt 53, and the rotational torque of the

motors

37R and 37L is applied to the belt Transmission to the rotating part 51 is possible. Note that the

motors

37R and 37L may be connected to the rotating component 51 by individual belts 53.
According to this configuration, by driving the

motors

37R and 37L, the distance between the two connecting

portions

45 and 46 is approached and separated, and the inner end portions of the left and right second links 27 are approached in synchronization.・ Separate.
Other configurations and operations are the same as those in 2 of the fourth embodiment.

(Effect of this embodiment)
This embodiment has the following effects in addition to the

effects

1 and 3 of the fourth embodiment.
(1) The approach / separation mechanism main body is a linear motion device 50 that converts the rotational motion of the rotating component 51 into a linear motion, and is between the first coupling portion 45 and the second coupling portion 46 by the linear motion. It is the composition which approaches and separates. The rotating component 51 is pivotally supported on the vehicle body 57 so as to be rotatable. The drive unit rotationally displaces the rotating component 51.
The rotary component 51 that directly drives the linear motion device 50 is pivotally supported on the vehicle body 57, so that the reaction force at the time of rotation of the rotary component 51 can be surely applied to the vehicle body 57. 50 can be activated.
(2) The drive unit includes

motors

37R and 37L, and transmits the torque of the

motors

37R and 37L to the rotating component 51 by belt transmission.
According to this configuration, the degree of freedom of the arrangement positions of the

motors

37R and 37L is improved by using belt transmission.

(Other)
Here, in 3 and 4 of 4th Embodiment, the space | interval of the 1st connection part 45 and the 2nd connection part 46 offset up and down of the pantograph-like link structure is changed with the screw rod 47 or the linear motion apparatus 50. The case is illustrated. As long as the distance between the first connecting part 45 and the second connecting part 46 can be changed, it may be realized by another mechanism. For example, a mechanism capable of changing the intersection angle between the upper

right arms

43 and 44 and the upper

left arms

40 and 41 may be provided in the first connecting portion 45.

As described above, the Japanese patent application 2012-166223 (filed on July 26, 2012), the Japanese patent application 2012-166224 (filed on July 26, 2012), the Japanese patent application 2012- The entire contents of 166228 (filed on July 26, 2012) and Japanese Patent Application 2012-166229 (filed on July 26, 2012) are hereby incorporated by reference.
Although the present invention has been described with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of each embodiment based on the above disclosure are obvious to those skilled in the art.

G Vehicle center of gravity 1 FL Drive wheel 2 Engine 3 Differential gear device 11 Shift position detection sensor 12 Auxiliary wheel 13 Auxiliary wheel lifting device 14 Lift motor control circuit 15 Controller 18 Braking control device 19 Auxiliary steering operation switch 20 Wheel support member 21 Upper link member 21 Upper link 22 Lower link member 23 Shock absorber 24 Suspension device 25 Auxiliary wheel support member 26 Link member 27 Link member 27 Link member (lift motor)
28 link 29 lift motor 30 auxiliary steering control unit 30A auxiliary wheel lift processing unit 30B power difference distribution processing unit 30C steering lock processing unit

Claims

An auxiliary steering device provided in a vehicle having left and right drive wheels that are arranged on one of the front side and the rear side of the vehicle and that are opposed to each other on the left and right sides,
An auxiliary wheel that is arranged on the other side of the front side or the rear side of the vehicle in plan view and used without driving;
An auxiliary wheel elevating device for elevating the auxiliary wheel with respect to the vehicle body;
A driving force difference adjusting device for generating a driving force difference between the left and right driving wheels when the auxiliary wheel is grounded;
An auxiliary steering device for a vehicle, comprising:
The driving force difference adjusting device generates the driving force difference by applying braking to one of the left and right driving wheels and transmitting the driving force to the other wheel. Item 2. The auxiliary steering device for a vehicle according to Item 1.
The driving force difference adjusting device distributes the power from the power source to the left and right driving wheels with a difference in power between the left and right driving wheels and the left and right independent braking control device capable of variably controlling the brake pressure individually. The auxiliary steering device for a vehicle according to claim 1, further comprising: a differential gear device that performs the operation.
The driving force difference adjusting device includes a left and right independent parking brake device capable of individually operating a parking brake for the left and right driving wheels, and a difference for distributing power from a power source to the left and right driving wheels with a power difference. The auxiliary steering device for a vehicle according to claim 1 or 2, further comprising a moving gear device.
The vehicle auxiliary steering device according to claim 1 or 2, wherein the driving force difference adjusting device includes an in-wheel motor in which a motor as an individual power source is mounted on the left and right driving wheels.
In plan view, when the auxiliary wheel is in contact with the auxiliary wheel, the extension line of the rotation shaft of the auxiliary wheel is directed toward the driving wheel where the driving force is relatively small among the left and right driving wheels. 6. The auxiliary steering device for a vehicle according to claim 2, wherein the auxiliary steering device is set.
The auxiliary steering device for a vehicle according to any one of claims 1 to 5, wherein the auxiliary wheel is a caster wheel whose direction of rotation changes according to an input from a road surface.
8. The plane according to claim 1, wherein the auxiliary wheel is located on a side opposite to the left and right driving wheels with respect to the center of gravity of the vehicle when the auxiliary wheel is grounded. A vehicle auxiliary steering apparatus as described in the paragraph.
An auxiliary steering device provided in a vehicle having a third wheel closer to the position of the auxiliary wheel than the left and right drive wheels in plan view, the third wheel being composed of two left and right wheels separated left and right. ,
9. The vehicle according to claim 8, wherein the auxiliary wheel is disposed at a position farther from the driving wheel than a line connecting ends of the two left and right wheels closer to the driving wheel in plan view. Auxiliary steering device.
7. The vehicle according to claim 6, wherein an operating direction of the auxiliary wheel that is lifted and lowered by the auxiliary lifting device is set to be perpendicular to a rotation axis of the auxiliary wheel in plan view. Auxiliary steering device.
An auxiliary steering device for a vehicle provided in a vehicle in which steered wheels are steered according to an operation amount of a steering operator operated for a steering instruction by a driver,
The auxiliary steering of a vehicle according to any one of claims 1 to 10, further comprising a steering operation limiting device that limits movement of the steering operator when the auxiliary wheel is in contact with the ground. apparatus.
An auxiliary steering method for a vehicle, comprising: left and right drive wheels, which are arranged on one of the front side and rear side of the vehicle and facing left and right, and a third wheel different from the left and right drive wheels. There,
A driving force difference is generated between the left and right driving wheels after the non-driving auxiliary wheel supported by the vehicle body is lowered and brought into contact with the ground to reduce or eliminate the ground load on the third wheel. An auxiliary steering method for a vehicle, characterized in that the vehicle is moved.
A wheel support member that rotatably supports a wheel is provided in a vehicle that is suspended from a vehicle body via a suspension member.
An auxiliary wheel support member for rotatably supporting the auxiliary wheel;
A first link that connects the auxiliary wheel support member and the wheel support member or the suspension member so as to be vertically swingable;
A second link for connecting the auxiliary wheel support member and the vehicle body so as to be vertically swingable;
A drive mechanism supported by the vehicle body for displacing the position of the auxiliary wheel side end of the second link in a direction approaching or separating from the wheel side end of the first link;
A lifting device for an auxiliary wheel, comprising:
The connection point of the first link to the wheel support member is set at a position higher than the connection point of the first link to the wheel support member in a state where at least the auxiliary wheel is grounded. The lifting device for auxiliary wheels described in 13.
The connection point of the first link to the auxiliary wheel support member and the connection point of the second link to the auxiliary wheel support member are arranged offset with respect to each other,
And a third link connecting the auxiliary wheel support member and the vehicle body,
The position of the connection point of the third link to the auxiliary wheel support member is lower than the position of the connection point of the second link to the auxiliary wheel support member. Lifting device for the auxiliary wheel described in 1.
The drive mechanism expands and contracts the second link to displace the position of the auxiliary wheel side end of the second link in a direction approaching and separating from the wheel side end of the first link. The auxiliary wheel lifting / lowering device according to any one of claims 13 to 15, wherein
The drive mechanism displaces the connecting point on the vehicle body side of the second link, so that the position of the auxiliary wheel side end of the second link approaches and separates from the wheel side end of the first link. The auxiliary wheel lifting / lowering device according to any one of claims 13 to 15, wherein the lifting / lowering device is displaced in a direction of moving.
The left and right wheels are rotatably supported by the left and right wheel support members, respectively, and the left and right wheel support members are respectively provided on a vehicle that is suspended from the vehicle body via a suspension.
It has left and right auxiliary wheels that are spaced apart in the vehicle width direction,
Each auxiliary wheel has an auxiliary wheel support member that rotatably supports the auxiliary wheel connected to the wheel support member or the suspension member via the first link so as to swing up and down, and via the second link. Connected to the vehicle body so that it can swing up and down,
Furthermore, an approach / separation mechanism for approaching / separating between the vehicle body side end portions of the left and right second links,
A drive unit attached to the vehicle body for driving the approach / separation mechanism;
A lifting device for an auxiliary wheel, comprising:
The approach / separation mechanism is a ball screw mechanism including a screw shaft extending in the vehicle width direction and a pair of nuts screwed to the screw shaft, and the drive unit is a motor that rotationally drives the screw shaft. ,
The screw shaft has a right-hand thread portion extending to the right side and a left-hand thread portion extending to the left side, and the screw directions of the right-hand thread portion and the left-hand thread portion are set in opposite directions, and the right-hand screw portion and the left-hand side Each nut is screwed to the thread part,
The vehicle body side end portion of the second link located on the right side is connected to the nut screwed to the right screw portion, and the vehicle body side end of the second link located on the left side to the nut screwed to the left screw portion. The lifting / lowering device for an auxiliary wheel according to claim 18, wherein the portions are connected.
The approach / separation mechanism is
Two right arms extending to the left second link side by connecting the outer end to the vehicle body side end of the second link on the right side, and an outer end portion on the vehicle body side end of the second link on the left side Of the two left arms extending to the right second link side, the inner end of one right arm of the two right arms, and one left arm of the two left arms. A first connecting portion that connects the inner end portion, an inner end portion of the other right arm of the two right arms, and an inner end portion of the other left arm of the two left arms are connected. A second connecting part, and an approach / separation mechanism main body that approaches / separates between the first connecting part and the second connecting part,
19. The lifting device for an auxiliary wheel according to claim 18, wherein the driving unit drives the approach / separation mechanism main body.
The approach / separation mechanism main body includes a screw shaft that connects the first connecting portion and the second connecting portion,
21. The lifting device for an auxiliary wheel according to claim 20, wherein the driving unit rotates and drives the screw shaft to approach and separate the first connecting unit and the second connecting unit.
The approach / separation mechanism main body is a linear motion device that converts the rotational motion of the rotating component into a linear motion, and is configured to approach / separate between the first connection portion and the second connection portion by the linear motion. And the above rotating parts are rotatably supported on the vehicle body,
21. The lifting device for an auxiliary wheel according to claim 20, wherein the driving unit rotationally displaces the rotating component.
23. The lifting device for an auxiliary wheel according to claim 22, wherein the driving unit is constituted by a motor, and transmits the torque of the motor to the rotating component by belt transmission.
The drive mechanism includes one approach / separation mechanism and two or more drive units that drive the approach / separation mechanism. When raising the auxiliary wheel, one drive unit of the two or more drive units is The auxiliary wheel lifting / lowering apparatus according to any one of claims 18 to 23, wherein an approach / separation mechanism is driven.