JP2014201164A - Auxiliary steering device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce wear of an auxiliary wheel in a case of performing an auxiliary steering while a part of a vehicle body is lifted.SOLUTION: An auxiliary steering device of a vehicle comprises: an auxiliary wheel 12 which is used to lift a vehicle body without driving force at the side of a third wheel different from right and left driving wheels; an auxiliary wheel lifting device which lifts up/down the auxiliary wheel 12 by using an auxiliary wheel support member; and a driving force difference adjusting device which can generate driving force difference between the right and left driving wheels when the auxiliary wheel 12 is grounded. A driving wheel, out of the right and left driving wheels, whose driving force generated by the driving force difference adjusting device is relatively small, is defined as a reference driving wheel. The auxiliary steering device of a vehicle includes a turning adjustment mechanism which can turn the auxiliary wheel 12 by a predetermined turning angle, when the auxiliary wheel lifting device lifts down the auxiliary wheel 12, or when the auxiliary wheel 12 rolls after being lifted down and grounded, so that a rotation axis S1 of the auxiliary wheel 12 turns toward the reference driving wheel side in a plan view.

Description

  The present invention relates to a technique for raising and lowering a non-driven auxiliary wheel provided separately from a wheel used for normal traveling. For example, a part of the vehicle body can be lifted by lowering the auxiliary wheel.

As an auxiliary steering device for a vehicle 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 a drivable auxiliary wheel that is different from the wheel used during normal traveling at the rear of the vehicle body. In the conventional auxiliary steering device, the auxiliary wheel is lowered while turning in the vehicle width direction, thereby grounding the auxiliary wheel and lifting the rear portion of the vehicle body. Thereafter, the lowered auxiliary wheel is rotationally driven so as to roll in the vehicle width direction. As a result, the apparatus described in Patent Document 1 enables the vehicle body to rotate on the spot.

Japanese Patent Laid-Open No. 4-95552

In the device described in Patent Document 1, the auxiliary wheel is fixedly supported so as to be rotatable around an axis in the vehicle front-rear direction (rollable in the vehicle width direction). For this reason, for example, when turning the vehicle body with the right wheel side or the left wheel side of the front wheel as the center of rotation, there is a difference between the direction in which the auxiliary wheel can roll and the moving direction of the auxiliary wheel accompanying the turning of the vehicle body. There was a problem that the auxiliary wheel was easily worn.
The present invention has been made paying attention to the above points, and an object thereof is to make it possible to reduce wear of auxiliary wheels.

  In order to solve the above-described problem, an aspect of the present invention provides an auxiliary wheel that is used in a non-driven manner to lift the vehicle body on the third wheel side different from the left and right driving wheels, and the auxiliary wheel includes an auxiliary wheel. An auxiliary wheel lifting device that moves up and down via a support member; and a driving force difference adjusting device that can generate a driving force difference between the left and right driving wheels when the auxiliary wheel is grounded. Of the left and right drive wheels, the drive wheel on the side where the drive force generated by the drive force difference adjusting device is relatively small is defined as the reference drive wheel. Then, as the auxiliary wheel lifting device lowers the auxiliary wheel or with rolling after the lowered auxiliary wheel touches down, the rotation shaft of the auxiliary wheel is directed to the reference driving wheel side in a plan view. A turning adjustment mechanism is provided that enables turning of the auxiliary wheel by a preset turning amount.

  According to one aspect of the present invention, the direction of the auxiliary wheel is set when the vehicle turns around the small turn using the auxiliary wheel by facilitating the rotation of the auxiliary wheel toward the reference drive wheel during auxiliary steering. It is possible to reduce the wear of the auxiliary wheel caused by the shift of the moving direction of the auxiliary wheel.

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 a figure explaining the example of the raising / lowering mechanism of the auxiliary wheel which concerns on embodiment based on this invention. It is a schematic diagram explaining a turning adjustment mechanism, (a) is a side view, (b) is a top view. 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 structure of an auxiliary steering control part. It is a flowchart figure explaining an example of processing of an auxiliary steering control part. It is a top view which shows the direction of an auxiliary wheel when turning a vehicle body using an auxiliary wheel. 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 showing an example of turning of vehicles by auxiliary steering concerning an embodiment based on the present invention. It is a schematic diagram explaining the caster angle of an auxiliary wheel, Comprising: (a) is a side view, (b) is a top view explaining the state in a grounding position. It is a figure explaining the example at the time of providing the spring as an elastic body, Comprising: (a) is a top view, (b) is a front view. It is a figure explaining the example at the time of providing the rubber bush as an elastic body, (a) is a top view, (b) is a front view. It is the figure which enabled rocking | fluctuation of the rotating shaft of an auxiliary wheel, Comprising: (a) is a top view, (b) is a side view. It is a figure explaining another example of the raising / lowering mechanism of the auxiliary wheel which concerns on embodiment based on this invention. It is a figure explaining another example of the raising / lowering mechanism of the auxiliary wheel which concerns on embodiment based on this invention. It is a schematic diagram explaining arrangement | positioning of an elastic member and a wire, Comprising: (a) is a bottom view, (b) is a side view. It is a figure explaining the structure which pulls a wire with a lever. It is a figure explaining the direction of the auxiliary wheel at the time of raising / lowering. It is a figure explaining the direction of the auxiliary wheel at the time of vehicle body turning. It is a figure explaining the example which provided the caster angle in the up-and-down axis of an auxiliary wheel. It is the figure seen from the vehicle back explaining the state which connected the wire to the raising / lowering apparatus. It is a figure explaining the mechanism which a wire other end part pulls, (a) is a figure showing the state where (b) has finished pulling, and the initial position before a wire is pulled.

Next, embodiments of the present invention will be described with reference to the drawings.
“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, 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.

  As shown in FIGS. 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 1 FL and 1 FR. 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 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.

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.

  Each auxiliary wheel 12 is rotatably attached to the auxiliary wheel support member 25 as shown in FIG. The auxiliary wheel support member 25 includes a first auxiliary wheel support member 25A and a second auxiliary wheel support member 25B. The first auxiliary wheel support member 25A includes a rotation shaft support portion 25Aa that supports the rotation shaft S1 of the auxiliary wheel 12 that extends in the lateral direction, and a disk-shaped first support plate that is provided above the rotation shaft support portion 25Aa. Part 25Ab. The first support plate portion 25Ab is set to be horizontal or substantially horizontal when the auxiliary wheel 12 is grounded. The second auxiliary wheel support member 25B is disposed above the first auxiliary wheel support member 25A, and supports the first auxiliary wheel support member 25A so as to be rotatable about the vertical axis S2. That is, the second auxiliary wheel support member 25B has a disk-like second support plate portion 25Ba facing the first support plate portion 25Ab from above at the lower portion. And 1st support plate part 25Ab and 2nd auxiliary wheel support plate part are connected so that relative rotation is possible around the said up-and-down axis S2 in the center part.

  In the present embodiment, as shown in FIG. 4, a pin 29 is provided that protrudes upward from the first support plate portion 25Ab of the first auxiliary wheel support member 25A. Further, a slit 31 as a guide part for guiding the pin 29 is formed in the second support plate part 25Ba of the second auxiliary wheel support member 25B. The slit 31 of the present embodiment is formed by a slit cut out in an arc shape along a circle centered on the vertical axis S2 in plan view, and the pin 29 is inserted into the slit 31 from below. Arranged in a state. Here, in the present embodiment, as shown in FIG. 4, the pair of the pin and the guide portion is formed at a symmetrical position about the vertical axis S <b> 2 in plan view. In FIG. 4, the set of the pin 29 and the guide portion is two sets and is arranged symmetrically. The arc length of the arc-shaped slit 31 is set to be less than 45 degrees (β <45 degrees) as a central angle with respect to the vertical axis S2. With the above configuration, the auxiliary wheel 12 has a structure that swings around the vertical axis S2. Further, as the auxiliary wheel 12 turns, the pin 29 moves along the slit 31 that is the guide portion due to the relative rotational displacement between the first support plate and the second support plate, and the pin 29 moves to the end of the slit 31 in the guide direction. The amount of relative rotational displacement between the first support plate portion 25Ab and the second support plate portion 25Ba is regulated by contacting the portion. That is, the turning amount of the auxiliary wheel 12 is regulated.

It supplements about the formation position of the said arc-shaped slit 31. FIG.
Here, in this embodiment, as will be described later, the auxiliary wheel 12 and the auxiliary wheel support member 25 are configured to move up and down while turning in the vehicle width direction by the operation of the auxiliary wheel lifting device 13. In view of this, the arcuate slit 31 is formed at a position where the auxiliary wheel 12 has a rotation axis S1 from a position where the rotation axis S1 faces the vehicle longitudinal direction (a position where the rolling direction faces the vehicle width direction). It is set so as to be able to turn by a preset turning amount (less than 45 degrees) toward the reference drive wheel side. With reference to at least the position where the rotation axis S1 of the auxiliary wheel 12 faces in the vehicle front-rear direction, the turning amount of the rotation shaft S1 toward the reference driving wheel side is greater than the turning amount of the rotation shaft S1 toward the direction away from the reference driving wheel side. Set smaller. Preferably, the turning amount in which the rotation axis S1 moves away from the reference drive wheel side is set to zero or small. Here, in the plan view, the angle from the state in which the rotation axis S1 faces the vehicle front-rear direction to the reference drive wheel side is the vehicle front-rear direction in the auxiliary wheels 12 arranged at the same position in the vehicle side view. From the perspective, the one closer to the reference drive wheel is smaller. For this reason, the arc length of the slit 31 may be set shorter as the auxiliary wheel 12 is disposed at a position relatively closer to the reference drive wheel.

An elastic body that urges the position of the pin 29 at the arc length position of the slit 31 toward the vehicle front-rear direction (the direction in which the rolling direction of the auxiliary wheel 12 is the turning direction when the auxiliary wheel 12 is raised or lowered). May be provided in the slit 31 or the like.
Further, as shown in FIGS. 1 and 5, 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.

  As shown in FIG. 3, the auxiliary wheel lifting device 13 is a device that supports each auxiliary wheel 12 on 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 as to be able to turn in the vehicle width direction, and drives the auxiliary wheel lift motor as will be described later. The auxiliary wheel 12 is moved up and down by moving the auxiliary wheel 12 while turning in the vehicle width direction so as to go downward from the inside in the direction toward the outside in the vehicle width direction. FIG. 3 illustrates the case where 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. 3 shows an 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. 3 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.

Then, the first auxiliary wheel support member 25 </ b> A of the auxiliary wheel support members 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 drive motor 27a extends and contracts with respect to the motor body. The lift motor 27 is a linear motion device. The motor main body 27b is connected to the vehicle body so as to be able to swing up and down, and the tip of the drive shaft 27a extending and contracting with respect to the motor main body 27b It is connected so that it can swing. That is, in the present embodiment, the length of the second link 27 is changed by configuring the second link 27 from a lift motor, so that the auxiliary link support member side end portion of the second link 27 is changed. Displace the position.

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.
Further, since the auxiliary wheel 12 rolls substantially in the vehicle width direction, it is preferable to set the turning of the auxiliary wheel 12 in the vehicle width direction when moving up and down. Of course, the link arrangement may be set so that the turning of the auxiliary wheel 12 at the time of raising and lowering is not in the vehicle width direction, for example, in the vehicle front-rear direction.

The lift motor control circuit 14 reads the motor position and current value from the lift motor 27 that moves up and down the auxiliary wheel 12 and controls the position of the lift motor 27.
As shown in FIG. 6, 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 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. 6, 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 </ b> A detects that the auxiliary steering operation switch 19 is turned on, the auxiliary wheel lift processing unit 30 </ b> 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.

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.
If 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, and when the auxiliary wheel 12 is lowered, the power difference distribution processing unit 30B 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 <b> 40, the auxiliary wheel lift processing unit 30 </ b> 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.
Here, when the plurality of auxiliary wheels 12 are lowered, the auxiliary wheels 12 may be controlled to come in contact in order from the auxiliary wheel 12 on the side close to the right front wheel 1FR that is a driving wheel that applies a braking force in a grounded state. When the plurality of auxiliary wheels 12 are raised, the auxiliary wheels 12 may be controlled to be separated from the auxiliary wheel 12 that is relatively far from the right front wheel 1FR that is a driving wheel that applies braking force in a grounded state.

(Operation other)
The raising / lowering operation | movement of the said auxiliary | assistant 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. By extending the drive shaft 27a, the auxiliary wheel 12 is directed inwardly and upwardly in the vehicle width direction in the vehicle width direction, with the connection point P3 of the third link 28 to the auxiliary wheel support member 25 as a swing center. The auxiliary wheel 12 is stored in the lower part of the vehicle body. As a result, as shown in FIG. 3B, the auxiliary wheel 12 is raised 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.
In the state where the auxiliary wheel 12 is stored as described above, the auxiliary wheel 12 can swing freely like a free caster, but the turning amount of the auxiliary wheel 12 is the arc length of the slit 31. Since this is limited to an angle (less than 45 degrees in angle), it is possible to reduce the swing of the auxiliary wheel 12 during normal driving of the vehicle. In addition, it is preferable to arrange | position buffer materials, such as a rubber material, in the both ends of the notch part which is a guide part.

  In addition, the auxiliary wheel 12 can roll by the arc length of the slit 31 as described above. However, when the vehicle is stationary, the rolling direction of the auxiliary wheel 12 depends on the shape and weight distribution of the auxiliary wheel support member 25. Thus, the center-of-gravity balance may be adjusted so as to face the same direction as the turning direction during ascent. By adjusting in this way, when the auxiliary wheel 12 is lowered and the auxiliary wheel 12 is brought into contact with the ground, the rolling direction of the auxiliary wheel 12 tends to be directed in the turning direction at the time of lowering (vehicle width direction in the present embodiment). . However, when an elastic body for positioning (biasing) the pin 29 to the initial value is provided, the adjustment of the balance of the center of gravity is not necessarily required.

  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, the auxiliary wheel 12 turns around the connection point P3 of the third link 28 to the auxiliary wheel support member 25 toward the outside in the vehicle width direction and downward. 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 as shown in FIG.

  When the auxiliary wheel 12 is grounded and lifts the rear part of the vehicle body, 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 rear wheel 1RL, 1RR is moved downward. The stroke amount 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.

  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.

  Even when the rear part of the vehicle body is lifted after the auxiliary wheel 12 starts to contact the ground, the auxiliary wheel 12 moves in the turning direction at the time of lowering (the vehicle width direction in the present embodiment), so the rolling direction of the auxiliary wheel 12 is the turning direction. It is preferable that the rotation axis S1 is oriented in the direction orthogonal to the turning direction. For this reason, the vertical axis S2 of the auxiliary wheel 12 (the axis at the time of turning corresponding to the kingpin axis) has a caster angle that tilts toward the vehicle width inward as viewed from the rear of the vehicle when the auxiliary wheel 12 is grounded. Preferably it is.

  However, in this embodiment, since the turning amount of the auxiliary wheel 12 is limited, the turning amount of the auxiliary wheel 12 after the auxiliary wheel 12 is grounded is kept small. For this reason, when the auxiliary wheel 12 is in contact with the ground, the rolling direction of the auxiliary wheel 12 can easily be directed in the vehicle width direction, and the amount of rolling from the vehicle width direction can be reduced. This makes it possible to reduce wear of the auxiliary wheel 12 when the auxiliary wheel 12 is grounded and the vehicle body is lifted.

  Further, the limitation on the amount of turning of the auxiliary wheel 12 is based on a plan view in which the rotation axis S1 of the auxiliary wheel 12 faces the vehicle front-rear direction (the rolling direction of the auxiliary wheel 12 is the vehicle width direction). It is set so that it can roll more in the direction toward the right front wheel 1FL, which is the reference drive wheel, than in the direction opposite to the direction toward the right front wheel 1FL. In this case, the rotation axis S1 of the auxiliary wheel 12 can easily be directed toward the right front wheel 1FL, which is the reference drive wheel, and the amount of rotation at that time can be kept small.

That is, in this embodiment, the raising / lowering operation of the vehicle body is used so that the auxiliary wheels 12 roll in the vehicle width direction. For this reason, the rotation axis S1 is automatically adjusted so that the rotation axis S1 of the auxiliary wheel 12 when moving up and down is directed in the vehicle front-rear direction. Thereby, unnecessary wear of the auxiliary wheel 12 associated with the raising and lowering of the auxiliary wheel 12 can be suppressed.
Further, according to the auxiliary steering device of the present embodiment, the auxiliary wheels 12 are provided at the lower portion of the vehicle body, and the auxiliary wheels 12 are supported on the road surface by the lifting device, so that the raised rear wheels 1RL and 1RR are In contrast, the restraining force in the horizontal direction is released.

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, the auxiliary wheel 12 and the auxiliary wheel support member 25 are connected via the rotation shaft S1 and are in a non-driving free state and have a movable range. In this case, the rotation axis S1 is automatically adjusted to the center at the time of turning by turning freely so that the rotation axis S1 of the auxiliary wheel 12 does not hinder the moment in the yaw direction generated in the vehicle body.

In the present embodiment, since the vehicle body rotates around the right front wheel 1FR, as shown in FIG. 8, the rotation axis S1 of the auxiliary wheel 12 is automatically adjusted so as to go to the right front wheel 1FR. . As described above, the rotation shaft S1 is directed to the center at the time of turning, whereby the auxiliary wheel 12 is more easily rolled. In FIG. 8, a symbol L indicates an extension line of the rotation axis S <b> 1 of the auxiliary wheel 12.
Thereby, unnecessary wear of the auxiliary wheel 12 associated with turning of the auxiliary wheel 12 can be suppressed.
The operating range of the auxiliary wheel 12 may be within the range in which the rotation axis S1 is directed from the direction in which the wheel rolls when moving up and down to the center at the time of rotation. Since it operates in the range toward the right front wheel 1FR, the limit amount of the movable range is an angle of less than 45 degrees.
Here, the raising operation of the lowered auxiliary wheel 12 is the storing operation described above.

Next, with reference to FIG. 9, the state transition of the operation state of the auxiliary steering device accompanying the operation of the driver will be described. That is, the turning operation of the vehicle using the auxiliary wheel 12 in a small turn 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. 3B, the auxiliary wheel 12 is stored on the vehicle body side, and the auxiliary wheel 12 is not grounded. 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. Further, the rear part of the vehicle body is lifted by the auxiliary wheel 12. 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. By bringing the right front wheel 1FR into a locked state, the right front wheel 1FR becomes a reference drive wheel, and the right front wheel 1FR side becomes the turning center when the vehicle is turned slightly.
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. 10 shows an example of the turning state of the vehicle MM at that time. As shown in FIG. 10, the minimum turning radius is reduced by turning the vehicle MM around the right front wheel 1FR.
The auxiliary wheel 12 that can roll at this time turns so that the rotation axis S1 of the auxiliary wheel 12 faces the right front wheel 1FR side that is the reference drive wheel, but the turning amount is limited to 45 degrees or less. The occurrence of turning is prevented. In addition, since the turning amount is limited in this way, the angle difference between the rolling direction and the moving direction of the auxiliary wheel 12 is suppressed to be small even before the rotation axis S1 faces the right front wheel 1FR. Further, it is possible to reduce the wear of the auxiliary wheel 12 and to reduce the twisting of the auxiliary wheel lifting / lowering device 13 that receives the load generated by lifting the rear part of the vehicle body, thereby avoiding an excessive load. Become.

Next, 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 a result, as the minimum turning radius of the vehicle becomes smaller than that in the normal state, as shown in FIG. 10, the space necessary for parallel parking becomes extremely small.

(Modification)
(1) In the above description, the pin 29 provided on the first auxiliary wheel support member 25A and the slit 31 as the guide portion provided on the second auxiliary wheel support member 25B to guide the pin 29 are provided. The case where the turning restriction portion is configured by defining the arc length of 31 is illustrated. However, the configuration of the turning restriction unit is not limited to the above configuration.
The guide portion may be formed of an arc-shaped groove that can accommodate the pin 29 instead of being formed by the slit 31. In short, it is sufficient that the pin 29 can be guided by a preset arc length. Further, the pin 29 may be provided on the second auxiliary wheel support member 25B, and the guide portion may be provided on the first auxiliary wheel support member 25A.

  (2) In the above description, the first auxiliary wheel support member 25A is configured to be rotationally displaced (turned) about the vertical axis S2 with respect to the second auxiliary wheel support member 25B. It is preferable that a caster angle is added to the vertical axis S <b> 2 so that the rolling direction of the auxiliary wheel 12 is easily directed to the moving direction of the auxiliary wheel 12. That is, as shown in FIG. 11, at the moment when the auxiliary wheel 12 is grounded, the intersection of the vertical axis and the ground is located farther from the reference driving wheel than the ground point of the auxiliary wheel 12, and the vertical axis It is preferable to incline from the vertical direction toward the direction away from the reference drive wheel from the top to the bottom. As a result, as the auxiliary wheel 12 rolls, the rolling direction of the auxiliary wheel 12 is easily oriented in the moving direction of the auxiliary wheel 12.

(3) As shown in FIGS. 12 and 13, elastic bodies 60 and 61 are interposed between the second auxiliary wheel support member 25B and the first auxiliary wheel support member 25A, which can be relatively rotated about the vertical axis S2. May be. The elastic bodies 60 and 61 constitute a turning restriction portion. In the case where a turning restriction portion including the pin 29 and the slit 31 is provided, the elastic bodies 60 and 61 may be set so as to function as positioning elastic bodies. The positioning position is, for example, a direction in which the turning direction during ascending / descending coincides with the rolling direction of the auxiliary wheel 12.
The elastic bodies 60 and 61 may be set so that the elastic force increases as the first auxiliary wheel support member 25A is displaced relative to the second auxiliary wheel support member 25B relative to the initial position.

  FIG. 12 shows an example of the winding spring 60, and FIG. 13 shows an example of the rubber bush 61. Such elastic bodies 60 and 61 are disposed so as to be sandwiched between the second support plate portion 25Ba of the second auxiliary wheel support member 25B and the first support plate portion 25Ab of the first auxiliary wheel support member 25A. To do. In the case of a spring, a space capable of accommodating the spring is formed on the opposing surfaces of the second support plate portion 25Ba and the first support plate portion 25Ab. Then, a spring is accommodated in the space, and one end of the spring is attached to the first support plate 25Ab and the other end is attached to the second support plate 25Ba.

As a result, the turning direction when the auxiliary wheel 12 is lowered (the vehicle width direction in the present embodiment) and the rolling direction of the auxiliary wheel 12 are the same direction. By rolling in the direction, wear of the auxiliary wheel 12 when the vehicle body is lifted is reduced. Furthermore, when the vehicle body is lifted and rotated by the auxiliary wheel 12, the rotational axis S1 of the auxiliary wheel 12 is changed so that the wear of the auxiliary wheel 12 is reduced by the balance between the yaw moment generated in the vehicle body and the force of the spring force. It is adjusted by facing.
When the auxiliary wheel 12 is retracted, the rotating shaft S1 automatically returns to the neutral position where it is in the longitudinal direction of the vehicle by the acting force of the spring.

In this embodiment, since the rotating shaft S1 is supported by a spring, noise and vibration generated from shaft play and play can be reduced even during storage.
In addition, you may arrange | position an elastic body to the outer peripheral side of 1st support plate part 25Ab and 2nd support plate part 25Ba which were opposingly arranged. As long as the first auxiliary wheel support member 25A is relatively rotated and displaced with respect to the second auxiliary wheel support member 25B, the elastic force may be increased.

(4) In the above description, the case where the second auxiliary wheel support member 25B and the first auxiliary wheel support member 25A are capable of relative rotational displacement has been described. The second auxiliary wheel support member 25B and the first auxiliary wheel support member 25A cannot be displaced relative to each other, and a turning restriction portion is provided for a portion of the first auxiliary wheel support member 25A that supports the rotation axis S1 of the auxiliary wheel 12. It may be provided.
The configuration will be described.

That is, as shown in FIG. 14, in the first auxiliary wheel support member 25 </ b> A, a portion that supports the rotation shaft S <b> 1 is a long hole 62 that extends in the lateral direction, and the rotation shaft S <b> 1 is movable along the long hole 62. By doing so, the auxiliary wheel 12 can be turned by a preset turning amount. About the amount and direction which can be turned, what is necessary is just to set similarly to what was demonstrated by the said pin 29 and guide part. For example, a bearing is provided at the end of the rotation shaft S 1, and the outer periphery of the bearing can be guided along the elongated hole 62.
Also in this case, it is preferable to provide an elastic body that positions the position of the rotation shaft S1 of the auxiliary wheel 12 with respect to the first auxiliary wheel support member 25A at the initial position.

(5) In the above embodiment, the wheel side end portion 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.
(6) 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.
(7) Since the left and right rear wheels 1RL and 1RR are lifted by the auxiliary wheel 12 to reduce the ground contact load, the left and right rear wheels 1RL and 1RR may be driving wheels 1FL and 1FR or driven wheels.

(8) 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.
(9) 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.
(10) In the above description, the auxiliary wheel 12 is illustrated as moving up and down while turning up and down in the vehicle width direction, but may be configured to move up and down in the vertical direction.
(11) The auxiliary wheel lifting device 13 is not limited to the configuration described above.

The auxiliary wheel lifting device 13 having another configuration will be described with reference to FIGS. 15 and 16.
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. 15 and 16 show an upper link 21 and a lower link 22 and a shock absorber 23 as an example of a suspension member constituting the suspension device 24.
As shown in FIGS. 15 and 16, 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.
The left and right auxiliary wheels 12 are rotatably supported by the left and right auxiliary wheel support members 25 as shown in FIGS. 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. 15 and 16. 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 </ b> R and 36 </ b> 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 </ b> R and 36 </ b> 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, the pin 29 and the slit 31 constitute a turning adjustment mechanism and a turning restriction unit. The slit 31 constitutes a guide part.

(Effect of this embodiment)
This embodiment has the following effects.
(1) As the auxiliary wheel lifting device lowers the auxiliary wheel 12 or with the rolling of the lowered auxiliary wheel 12 after grounding, the rotation shaft of the auxiliary wheel 12 is directed toward the reference driving wheel in plan view. Thus, a turning adjustment mechanism is provided that enables turning the auxiliary wheel 12 by a preset turning amount.
According to this configuration, by restricting the turning amount, the angle difference between the moving direction of the auxiliary wheel 12 and the rolling direction of the auxiliary wheel 12 when the auxiliary wheel 12 is lowered by lowering the vehicle body can be reduced. Further, since the rotation axis of the auxiliary wheel 12 during the auxiliary steering is easily directed toward the reference drive wheel side, the direction of the auxiliary wheel 12 and the auxiliary wheel 12 are turned when the vehicle turns around using the auxiliary wheel 12. It is possible to reduce the wear of the auxiliary wheel 12 caused by a shift in the moving direction of the auxiliary wheel 12. That is, it is possible to reduce the occurrence of wear of the auxiliary wheels 12 when performing a part of the vehicle body for auxiliary steering.

  In addition, as the moving direction of the auxiliary wheel 12 and the rolling direction of the auxiliary wheel 12 are different, the load applied to the auxiliary wheel 12 from the ground increases, and as the auxiliary wheel 12 is worn, A large load acts accordingly. This affects the durability of the portion that supports the auxiliary wheel 12. In this respect, in the present embodiment, the angle difference between the moving direction of the auxiliary wheel 12 and the rolling direction of the auxiliary wheel 12 is suppressed to be small, and such problems can be reduced.

(2) The turning adjustment mechanism includes a turning restriction unit that restricts the turning amount of the auxiliary wheel 12 when the auxiliary wheel 12 is grounded.
As a result, the turning amount of the auxiliary wheel 12 can be limited.
(3) The turning restricting portion includes a pin protruding vertically from one of the first auxiliary wheel support member and the second auxiliary wheel support member toward the other of the first auxiliary wheel support member and the second auxiliary wheel support member. And a guide portion that is provided on the other of the first auxiliary wheel support member and the second auxiliary wheel support member and guides the pin. The guide portion restricts a relative movement amount of the pin accompanying a relative rotational displacement around the vertical axis of the first auxiliary wheel support member with respect to the second auxiliary wheel support member to a predetermined amount.
According to this configuration, the turning amount of the auxiliary wheel 12 can be limited mechanically.

(4) The turning restriction portion is provided in a support portion for supporting the rotation shaft of the auxiliary wheel 12 in the auxiliary wheel support member, and the rotation shaft of the auxiliary wheel 12 is set in advance to the auxiliary wheel support member. Only the lateral displacement is possible.
According to this configuration, the turning amount of the auxiliary wheel 12 can be limited mechanically.
(5) The turning adjustment mechanism includes an elastic body interposed between the first auxiliary wheel support member and the second auxiliary wheel support member.
According to this configuration, the turning amount of the auxiliary wheel 12 can be limited mechanically.
Moreover, it becomes possible to suppress the sound and vibration at the time of rattling by suppressing the play by the elastic body. It is also possible to bias the auxiliary wheel 12 in a preset direction with an elastic body.

(6) In plan view, when the lowered auxiliary wheel 12 is grounded, the intersection of the vertical axis and the ground is located farther from the reference drive wheel than the ground point of the auxiliary wheel 12 and The shaft is inclined from the vertical direction toward the direction away from the reference drive wheel as it goes downward from above.
According to this structure, it becomes easy to turn so that the rotating shaft of the auxiliary wheel 12 faces the reference drive wheel side by the load force acting on the auxiliary wheel 12 during turning.
(7) When the auxiliary wheel 12 is not grounded, the rolling direction of the auxiliary wheel 12 faces the same direction as the turning direction in plan view.
This makes it possible to suppress wear of the auxiliary wheel 12 when the auxiliary wheel 12 is lowered and a part of the vehicle body is lifted.

(Second Embodiment)
Next, a second embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the member similar to the said embodiment.
In the first embodiment, wear of the auxiliary wheel 12 is prevented by automatically turning the auxiliary wheel 12 as the auxiliary wheel 12 moves while limiting the turning amount of the auxiliary wheel 12 due to rolling when the auxiliary wheel 12 contacts the ground. At the same time, by limiting the amount of turning, unnecessary touching was suppressed.
On the other hand, in the second embodiment, the direction of the auxiliary wheel 12 is urged to the initial position by an elastic member, and the auxiliary wheel 12 can be rolled by a pulling operation using a wire.
Here, in the present embodiment, as an example of the configuration of the auxiliary wheel lifting device, a case in which a mechanism for lifting and lowering the left and right auxiliary wheels 12 in synchronization is employed as shown in FIGS. However, the configuration of the auxiliary wheel lifting device may be another configuration as shown in FIG.

  As in the first embodiment, the auxiliary wheel 12 is rotatably attached to the auxiliary wheel support member 25 with the rotation shaft S1. The auxiliary wheel support member 25 includes a first auxiliary wheel support member 25A and a second auxiliary wheel support member 25B. The first auxiliary wheel support member 25A includes a rotation shaft support portion 25Aa that supports the rotation shaft S1 of the auxiliary wheel 12 that extends in the lateral direction, and a disk-shaped first support plate that is provided above the rotation shaft support portion 25Aa. Part 25Ab. The first support plate portion 25Ab is set to be horizontal or substantially horizontal when the auxiliary wheel 12 is grounded. The second auxiliary wheel support member 25B is disposed above the first auxiliary wheel support member 25A, and supports the first auxiliary wheel support member 25A so as to be rotatable about the vertical axis S2. That is, the second auxiliary wheel support member 25B has a disk-like second support plate portion 25Ba facing the first support plate portion 25Ab from above at the lower portion. And 1st support plate part 25Ab and 2nd auxiliary wheel support plate part are connected so that relative rotation is possible around the said up-and-down axis S2 in the center part.

Here, the rolling direction of the auxiliary wheel 12 defines the vehicle width direction (that is, the same direction as the turning direction when descending) as the initial position.
As shown in FIG. 17A, an elastic member 63 is interposed between the first support plate portion 25 </ b> Ab and the second support plate portion 25 </ b> Ba that are opposed in the vertical direction. The elastic member 63 of the present embodiment is configured by a coil spring, and by attaching one end portion of the elastic member 63 to the first support plate portion 25Ab and the other end portion to the second support plate portion 25Ba, the vertical axis S2 is set. As the rotation axis S1, the first support plate portion 25Ab and the second support plate portion 25Ba are arranged so as to be able to apply an elastic force in a direction in which they are relatively rotationally displaced. Specifically, the elastic force is set so that the rolling direction of the auxiliary wheel 12 is directed toward the initial position. In the present embodiment, the two coil springs are used as the elastic member 63, and the two auxiliary springs 12 are arranged symmetrically with respect to the initial position in plan view in a state where the auxiliary wheel 12 is positioned at the initial position. Thus, the auxiliary wheel 12 is biased more reliably to the initial position. In the present embodiment, as shown in FIG. 17A, which is a view of the second support plate portion 25Ba as viewed from below, one end portion of the elastic member 63 is connected to the pin 29, and the other end portion is connected to the second portion. The example connected with support plate part 25Ba is shown.

  A wire cable 64 is also provided. The wire cable 64 includes a cylindrical cable and a wire 65 disposed along the cable in the hollow cable. Both ends of the wire 65 protrude from both ends of the cable. The wire 65 cable has the same mechanism as that of a brake wire used for a manual brake or the like.

  As shown in FIG. 17A, one end portion 65a of the wire 65 is connected to the mounting portion 25Ac of the first auxiliary wheel support member 25A. The wire cable 64 extends substantially laterally from the outer edge portion of the first support plate portion 25Ab, and the middle portion of the cable is fixed to the lower surface of the second support plate portion 25Ba with a fixture 66. As a result, when the other end portion of the wire 65 is pulled, one end portion of the wire is pulled toward the outer edge portion side of the second support plate portion 25Ba, so that the first support is provided against the spring force of the elastic member 63. The plate portion 25Ab is capable of relative rotational displacement about the vertical axis S2 with respect to the second support plate portion 25Ba. The rotational displacement direction is determined from the state in which the auxiliary wheel 12 is biased to the initial position by the elastic member 63 and the rotation axis S1 of the auxiliary wheel 12 is in the vehicle longitudinal direction (the rolling direction is the vehicle width direction). The rotation axis S1 of the wheel 12 is set in a direction facing the reference drive wheel side.

Further, as shown in FIG. 18, the wire cable 64 extends from the position fixed to the second support plate portion 25Ba toward the upper vehicle body position, and the cable is fixed at the position. At this time, the wire cable 64 is bent to allow the auxiliary wheel 12 to move up and down. Furthermore, the extending direction of the wire cable 64 is changed to the front in the vehicle front-rear direction, and the wire cable 64 extends toward the passenger compartment side. The other end 65b of the wire 65 is connected to the other end of an auxiliary steering lever 67 provided in the passenger compartment. Then, by operating the auxiliary steering lever 67, the other end portion of the wire 65 is displaced by a preset operation amount, and accordingly, the wire 65 slides in the cable, and the displacement of the other end portion is changed. It is transmitted to one end side of the wire 65. As a result, the first support plate portion 25Ab is rotationally displaced relative to the second support plate portion 25Ba against the spring force of the positioning elastic member. As a result, the rotation shaft S1 of the auxiliary wheel 12 is moved to the drive wheel side. Turn to. Further, by returning the auxiliary steering lever 67 to the initial position (release position), the rotation shaft S1 of the auxiliary wheel 12 is returned to a position facing the vehicle front-rear direction.
Other configurations are the same as those in the first embodiment.

(Operation)
In the state in which the auxiliary wheel 12 is stored, the auxiliary wheel 12 can swing freely like a free caster. However, the rotation shaft S1 of the auxiliary wheel 12 is moved in the vehicle front-rear direction (the rolling direction) by an elastic body. Is biased toward the vehicle width direction), the swinging of the auxiliary wheels 12 during traveling is reduced.
Next, the operation during auxiliary steering will be described.
When the vehicle is stopped and 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, the auxiliary wheel 12 moves in the vehicle width direction so as to go 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 swing. Turn up and down. As a result, the auxiliary wheel 12 descends from the vehicle width direction inner side toward the vehicle width direction outer side and contacts the ground, and the auxiliary wheel 12 further descends and lifts the rear part of the vehicle body as shown in FIG. . At this time, as shown in FIG. 19, since the rolling direction of the auxiliary wheel 12 is directed in the vehicle width direction, the moving direction of the auxiliary wheel 12 and the rolling direction coincide with each other or substantially coincide with each other and the auxiliary wheel 12 is worn. Can be reduced.

Then, the auxiliary steering control unit 30 provides information indicating that auxiliary steering is possible after applying a braking force to the right front wheel 1FR to place the right front wheel 1FR in a locked state. By bringing the right front wheel 1FR into a locked state, the right front wheel 1FR becomes a reference drive wheel, and the right front wheel 1FR side becomes the turning center when the vehicle is turned slightly.
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.
Also, before and after the selection of the turning direction, the occupant pulls the auxiliary steering lever 67 so that the rotation axis S1 of the auxiliary wheel 12 faces the right front wheel 1FL, which is the reference driving wheel, as shown in FIG. Roll to.

  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.
Further, when retracting the lowered auxiliary wheel 12, the occupant returns the auxiliary steering lever 67, so that the auxiliary wheel 12 is moved to its initial position (the rolling direction is the vehicle width direction) by the elastic force of the elastic body. That is, it rolls to the same position as the turning direction.
When the auxiliary wheel 12 is turned after this state is reached, the rolling direction and the turning direction of the auxiliary wheel 12 become the same direction, and wear of the auxiliary wheel 12 can be reduced even when the auxiliary wheel 12 is stored.

(Modification)
(1) The case where the occupant manually performs the operation of the auxiliary steering lever 67 is not limited to this. For example, the operation may be automatically performed by an actuator such as a motor in accordance with the operation of the auxiliary steering device. For example, the auxiliary steering control unit 30 controls the auxiliary steering lever 67 to be pulled in synchronism with applying a braking force to the right front wheel 1FR to bring the right front wheel 1FR into a locked state. When there is a command to raise the auxiliary wheel 12, the lever 67 is controlled to return. Alternatively, control may be performed so that the lever 67 is automatically operated depending on whether the auxiliary wheel 12 is raised or lowered.

(2) Further, the wire 65 may be linked to a parking (side) brake (not shown) for interlocking.
(3) Further, as shown in FIG. 21, it is preferable that a caster angle is added to the vertical axis S <b> 2 of the auxiliary wheel 12 so that the rolling direction of the auxiliary wheel 12 is easily oriented in the moving direction of the auxiliary wheel 12. That is, as in FIG. 11 described above, at the moment when the auxiliary wheel 12 is grounded, the intersection of the vertical axis and the ground is located farther from the reference drive wheel than the ground point of the auxiliary wheel 12 and It is preferable that the shaft is inclined from the vertical direction in a direction away from the reference drive wheel as it goes downward from above. As a result, as the auxiliary wheel 12 rolls, the rolling direction of the auxiliary wheel 12 is easily oriented in the moving direction of the auxiliary wheel 12.

(4) You may connect the other end part 65b of the said wire 65 to the movable part of a raising / lowering apparatus. At this time, after the auxiliary wheel 12 is grounded, the wire 65 is moved according to the movement from the position immediately before the position where the lowering of the auxiliary wheel 12 is completed (the position where the rear part of the vehicle body after the grounding is lifted) is completed. Set to shrink.
When the wire 65 configuration is set in this way, when the stored auxiliary wheel 12 is lowered, the auxiliary wheel 12 is lowered while turning in the vehicle width direction while being urged by the elastic body in the rolling direction. The grounding is performed in a state where the turning direction and the rolling direction of the auxiliary wheel 12 are the same, and the auxiliary wheel 12 is further lowered to lift the rear portion of the vehicle body. Subsequently, as the descent of the auxiliary wheel 12 proceeds, the rotation shaft S1 of the auxiliary wheel 12 gradually turns to the reference drive wheel side. Thereby, the rolling direction of the auxiliary wheel 12 at the time of auxiliary steering by the auxiliary wheel 12 is set to the same direction as the turning direction of the rear part of the vehicle body. As described above, the wear of the auxiliary wheel 12 can be reduced.
Further, when storing the lowered auxiliary wheel 12, the direction of the auxiliary wheel 12 returns to the initial value in the vehicle width direction at the beginning of the raising of the auxiliary wheel 12, and thereafter, the turning direction and the auxiliary wheel 12 accompanying the raising. It becomes possible to reduce the wear of the auxiliary wheel 12 until the rolling direction of the auxiliary wheel 12 becomes the same direction and the auxiliary wheel 12 comes in contact with and separates.

An example in which the other end portion 65b of the wire 65 is interlocked with the movable portion of the lifting device will be described with reference to FIGS.
A sleeve 71 made of a hollow cylinder is disposed in parallel with the screw shaft 35. The sleeve 71 has two sets of long holes 71a extending in the axial direction of the sleeve. The two sets of long holes 71a are arranged so as to be symmetric in the vehicle width direction. Each pair of long holes 71a is composed of two long holes 71a arranged to face each other in the vehicle longitudinal direction. Moreover, the connecting rod 72 is arrange | positioned so that each group of long holes 71a may be penetrated, and this connecting rod 72 can move along the target long hole 71a. The wire 65 is inserted from the opening at the end of the sleeve, and the other end 65 b of the wire 65 is connected to the connecting rod 72. As a result, the connecting rod 72 moves along the elongated hole 71a, whereby the other end portion 65b of the wire 65 moves.

A ring member 70 is coaxially disposed on the outer periphery of the sleeve 71, and the ring member 70 is fixed to the nut 36. As a result, the ring member 70 moves in the vehicle width direction together with the nut 36, that is, in conjunction with the nut 36. When the ring member 70 comes into contact with the connecting rod 72, the connecting rod 72 moves together with the ring member 70. Thus, the other end 65b of the wire 65 is pulled. Accordingly, by appropriately adjusting the position of the long hole 71a, it is possible to adjust the timing of pulling the wire 65 accompanying the raising and lowering of the auxiliary wheel 12. The state of FIG. 23B is a state where the wire 65 has been pulled.
In addition, according to the raising / lowering apparatus employ | adopted, it can respond by arrange | positioning the sleeve 71 in parallel with the movable direction of the movable part, and connecting the said ring member 70 to a movable part.
Here, the wire 65 and the elastic member 63 constitute a turning adjustment mechanism. The nut 36 constitutes a movable part.

(Effect of this embodiment)
This embodiment has the following effects in addition to the corresponding effects of the first embodiment.
(1) The turning adjustment mechanism biases the first auxiliary wheel support member against the second auxiliary wheel support member in a direction in which the rolling direction of the auxiliary wheel 12 faces in the same direction as the turning direction in a plan view. An elastic member is provided. Further, one end of the auxiliary wheel support member is connected to the first auxiliary wheel support member, and the one end of the first auxiliary wheel support member is pulled to support the second auxiliary wheel in a direction in which the rotation shaft of the auxiliary wheel 12 faces the reference drive wheel in plan view. A wire capable of turning the first auxiliary wheel support member with respect to the member by a preset turning amount is provided.
According to this configuration, the auxiliary wheel 12 can be biased to a preset initial position by the elastic member, and the auxiliary wheel 12 can be turned by a preset turning amount by wire operation.

(2) The other end portion of the wire is configured to be displaceable in conjunction with the movable portion of the auxiliary wheel lifting device. One end of the wire is pulled during the operation after the auxiliary wheel 12 is grounded during the lowering operation of the auxiliary wheel 12 by the operation of the auxiliary wheel lifting device, so that the rotation shaft of the auxiliary wheel 12 is the reference driving wheel in a plan view. In the direction toward the side, the first auxiliary wheel support member is turned by a preset turning amount with respect to the second auxiliary wheel support member.
According to this configuration, the auxiliary wheel 12 can be turned in a desired direction by pulling the wire in conjunction with the raising and lowering of the auxiliary wheel 12.

G Vehicle center of gravity MM Vehicle S1 Rotating shaft 1FL, 1FR Left and right front wheels (drive wheels)
1FR Reference drive wheel 1RL, 1RR Left and right rear wheels (third wheel)
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 22 Lower Link 23 Shock Absorber 24 Suspension Device 25 First Auxiliary Wheel Support Member 25Aa Rotating Shaft Support portion 25Ab First support plate portion 25Ac Mounting portion 25B Second auxiliary wheel support member 25Ba Second support plate portion 29 Pin 30 Auxiliary steering control portion 30A Lift processing portion 30B Power difference distribution processing portion 31 Slit 35 Screw shaft 36 Nut 57 Car body 60 Spring 60, 61 Elastic body 61 Rubber bushing 62 Long hole 63 Elastic member 64 Wire cable 65 Wire 65a One end 65b Other end 66 Fixing tool 67 Auxiliary steering lever 70 Ring member 71 Sleeve 71a Long hole 72 Connecting rod

Claims (9)

A vehicle steering apparatus provided in a vehicle including left and right drive wheels and a third wheel different from the left and right drive wheels,
An auxiliary wheel that is disposed in a position closer to the third wheel than the driving wheel in plan view and is used without driving;
An auxiliary wheel support member for rotatably supporting the rotation shaft of the auxiliary wheel;
An auxiliary wheel elevating device for elevating the auxiliary wheel with respect to the vehicle body by elevating the auxiliary wheel support member; and
A driving force difference adjusting device capable of generating a driving force difference between the left and right driving wheels when the auxiliary wheel is grounded,
When the driving wheel on the side where the driving force generated by the driving force difference adjusting device among the left and right driving wheels is relatively small is defined as a reference driving wheel,
As the auxiliary wheel lifting device lowers the auxiliary wheel or with rolling of the lowered auxiliary wheel after grounding, the auxiliary wheel is rotated so that the axis of rotation of the auxiliary wheel faces the reference drive wheel in a plan view. An auxiliary steering device for a vehicle, comprising: a turning adjustment mechanism that enables turning of a wheel by a set turning amount set in advance. The turning adjustment mechanism is
2. The auxiliary steering device for a vehicle according to claim 1, further comprising a turning restriction unit that restricts a turning amount of the auxiliary wheel when the auxiliary wheel is grounded. The auxiliary wheel support member includes: a first auxiliary wheel support member that supports a rotation shaft of the auxiliary wheel; and a second auxiliary wheel support member that rotatably supports the first auxiliary wheel support member about a vertical axis. Prepared,
The auxiliary wheel elevating device raises and lowers the auxiliary wheel by raising and lowering the second auxiliary wheel support member,
The turning restricting portion includes a pin projecting up and down from one of the first auxiliary wheel support member and the second auxiliary wheel support member toward the other of the first auxiliary wheel support member and the second auxiliary wheel support member, A guide portion provided on the other of the first auxiliary wheel support member and the second auxiliary wheel support member and guiding the pin,
The guide portion restricts a relative movement amount of the pin with a relative rotational displacement around the vertical axis of the first auxiliary wheel support member with respect to the second auxiliary wheel support member to a predetermined amount. The auxiliary steering device for a vehicle according to claim 2.   The turning restriction portion is provided in a support portion that supports the rotation shaft of the auxiliary wheel in the auxiliary wheel support member, and the rotation shaft of the auxiliary wheel can be laterally displaced by a preset amount with respect to the auxiliary wheel support member. The auxiliary steering device for a vehicle according to claim 2, wherein the auxiliary steering device is configured as follows. The auxiliary wheel support member includes: a first auxiliary wheel support member that supports a rotation shaft of the auxiliary wheel; and a second auxiliary wheel support member that rotatably supports the first auxiliary wheel support member about a vertical axis. Prepared,
The auxiliary wheel elevating device raises and lowers the auxiliary wheel by raising and lowering the second auxiliary wheel support member,
The said turning adjustment mechanism is equipped with the elastic body interposed between the said 1st auxiliary wheel support member and a 2nd auxiliary wheel support member, The any one of Claims 1-3 characterized by the above-mentioned. A vehicle auxiliary steering device as described. The auxiliary wheel support member includes: a first auxiliary wheel support member that supports a rotation shaft of the auxiliary wheel; and a second auxiliary wheel support member that rotatably supports the first auxiliary wheel support member about a vertical axis. Prepared,
The auxiliary wheel lifting device raises and lowers the auxiliary wheel by raising and lowering the second auxiliary wheel support member,
In plan view, when the lowered auxiliary wheel comes into contact with the ground, the intersection of the vertical axis and the ground is located farther from the reference drive wheel than the ground point of the auxiliary wheel, and the vertical axis is from above. The auxiliary steering device for a vehicle according to any one of claims 1 to 5, wherein the auxiliary steering device is inclined from a vertical direction toward a direction away from the reference drive wheel as it goes downward. The auxiliary wheel lifting device raises and lowers the auxiliary wheel with respect to the vehicle body by raising and lowering the auxiliary wheel support member while turning it up and down in a predetermined turning direction.
The vehicle assistance according to any one of claims 1 to 6, wherein the rolling direction of the auxiliary wheel faces the same direction as the turning direction in a plan view when the auxiliary wheel is in a non-grounding state. Steering device. The auxiliary wheel lifting device is configured to raise and lower the auxiliary wheel with respect to the vehicle body by raising and lowering the auxiliary wheel support member while turning up and down in a predetermined turning direction.
The auxiliary wheel support member includes: a first auxiliary wheel support member that supports a rotation shaft of the auxiliary wheel; and a second auxiliary wheel support member that rotatably supports the first auxiliary wheel support member about a vertical axis. Prepared,
The turning adjustment mechanism is
An elastic member that biases the first auxiliary wheel support member against the second auxiliary wheel support member in a direction in which the rolling direction of the auxiliary wheel faces the same direction as the turning direction in plan view;
One end of the first auxiliary wheel support member is connected to the second auxiliary wheel support member in a direction in which a rotation axis of the auxiliary wheel is directed toward the reference drive wheel in a plan view when the one end portion is pulled. The auxiliary steering device for a vehicle according to claim 1, further comprising: a wire that can turn the first auxiliary wheel support member by a preset turning amount.   The other end portion of the wire is configured to be displaceable in conjunction with the movable portion of the auxiliary wheel lifting device, and the wire of the wire is operated during the operation after the auxiliary wheel is grounded while the auxiliary wheel is being lowered by the operation of the auxiliary wheel lifting device. The first auxiliary wheel support member is set in advance with respect to the second auxiliary wheel support member in a direction in which the rotation shaft of the auxiliary wheel is directed toward the reference drive wheel in a plan view by pulling one end portion. The auxiliary steering device for a vehicle according to claim 8, wherein the vehicle is turned by a set turning amount.

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