JP2014210484A - Vehicle with four-wheel steering mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable lateral movement, turning in a small radius, etc. without using a complex mechanism in a vehicle (4 WS) that steers four wheels.SOLUTION: The vehicle with a four-wheel steering mechanism includes: rack cases 10, 20 connected to right and left wheels W of front and rear wheels; a rack bar 11 penetrating through the rack cases 10, 20, which can steer the right and left wheels W by movement in a horizontal direction relative to a direct advance direction of the vehicle 1; longitudinal moving means for moving the rack cases 10, 20 in a longitudinal direction; and an in-wheel motor M installed in each wheel W to which the rack bars 11, 21 are connected.

Description

  The present invention relates to a vehicle equipped with a four-wheel steering mechanism.

Ackerman-Jantou type is used to steer the wheels using a steering link mechanism that connects the left and right wheels (hereinafter collectively referred to as "wheels" including tires, wheels, hubs, in-wheel motors, etc.) There is a steering mechanism called. This steering mechanism uses a tie rod and a knuckle arm so that the left and right wheels have the same turning center when the vehicle turns.

  There is also a steering mechanism provided with an actuator that changes either the length of the tie rod, the distance between the left and right tie rods, or the angle formed by each wheel and the knuckle arm. According to this steering mechanism, all of normal traveling, parallel movement, and small traveling can be smoothly performed, and the response is excellent (see, for example, Patent Document 1).

  Further, the steering mechanism is arranged between the left and right wheels of the front and rear wheels, and includes a rack bar that is rotatable about an axis and divided into left and right, and a forward / reverse switching means between the two divided rack bars. There is. The forward / reverse switching means can transmit the rotation of one of the divided rack bars to the other in the forward / reverse direction. According to this steering mechanism, movements such as a steering angle of 90 degrees and lateral movement are possible (for example, see Patent Document 2).

  There is a technique of a four-wheel steered vehicle in which an actuator is operated in accordance with the steering of the front wheels to steer the rear wheels (see, for example, Patent Document 3). In addition, there is also a steering mechanism technique in which the toe adjustment of the left and right wheels is performed by moving the rack housing connecting the left and right wheels in the front-rear direction to improve running stability (see, for example, Patent Document 4).

Japanese Patent Laid-Open No. 04-262971 JP 2007-22159 A Utility Model Registration No. 2600374 Japanese Patent Laid-Open No. 2003-127876

  According to a general Ackermann-Jantou-type steering link mechanism, during normal driving, a line extending vertically from the rotation line of each wheel (the center line in the width direction of the wheel) gathers at the turning center of the vehicle. Smooth running is possible. However, when the lateral movement of the vehicle (transverse movement in the lateral direction with the vehicle facing in the front-rear direction) is obtained, steering the wheel in a direction of 90 degrees with respect to the front-rear direction is a problem with the length of the steering link. It is difficult to interfere with other members. Further, even if one of the left and right wheels is steered at 90 degrees, the other wheel is not completely parallel to the one wheel, and smooth running is difficult.

  Further, in this type of vehicle, the front wheels that are main steered wheels can be steered in a predetermined traveling direction of the vehicle, and the rear wheels that are follower steered wheels are set in parallel with the longitudinal direction of the vehicle. ing. For this reason, when the front wheel of this vehicle is steered and turned, the front wheel and the rear wheel do not coincide with the turning circle. Therefore, at low vehicle speeds, the vehicle turns in a posture in which the rear wheels enter the inside of the turning circle due to the inner wheel difference, and at high vehicle speeds, the vehicle turns in a posture in which the front wheels enter the inside of the turning circle by centrifugal force. That is, there is a problem that even if the front wheels are steered in the turning direction, which is the traveling direction of the vehicle, the vehicle posture cannot be made to match the turning direction. Therefore, there is a vehicle having a four-wheel steering mechanism (four-wheel steering device) that improves not only the front wheels but also the rear wheels to improve traveling performance.

  As a vehicle having a four-wheel steering mechanism (a so-called 4WS vehicle), for example, in the technique described in Patent Document 1, it is possible to move the vehicle in the lateral direction, make a small turn, and the like. However, since an actuator for changing the length of the tie rod, the distance between the left and right tie rods, or the angle formed by the wheel and the knuckle arm is provided, the number of actuators is large and the control is complicated. Patent Document 2 not only has a complicated structure due to its mechanism, but also uses a large number of gears to steer the wheels by the rotation of the rack bar. For this reason, rattling is likely to occur, and it is difficult to smoothly steer the wheels.

  Patent Document 3 is an example of a conventional four-wheel steering mechanism. Although the rear wheel can be steered, it is difficult to move in the lateral direction with this mechanism alone for the same reason described above. Further, although Patent Document 3 can perform toe adjustment, it cannot cope with a lateral movement or a small turn of the vehicle.

  Accordingly, an object of the present invention is to make it possible to cope with lateral movement, small turn, and the like in a vehicle (4WS) that gives a steering angle to four wheels without using a complicated mechanism.

  In order to solve the above-described problems, in the steering device of the present invention, rack bars that pass through the rack case are connected to the left and right wheels of the front wheels and the rear wheels via tie rods, and the rack bars are connected to the left and right wheels with respect to the straight traveling direction of the vehicle. The left and right wheels can be steered by movement in a direction, and includes a front-rear moving means for moving the rack case in the front-rear direction, and an in-wheel motor on each wheel to which the rack bar is connected via a tie rod. A vehicle equipped with a four-wheel steering mechanism was adopted.

  Moreover, it may replace with the said back-and-forth moving means, and may be provided with the up-and-down moving means which moves the said rack case to an up-down direction. That is, it has rack bars connected to the left and right wheels of the front and rear wheels, and the rack bar can steer the left and right wheels by movement in the left and right direction with respect to the straight traveling direction of the vehicle. It is the structure of the vehicle provided with the four-wheel steering mechanism which has an in-wheel motor in each wheel to which the said rack bar was connected, and the up-and-down moving means to move up and down. Furthermore, you may provide both the said back-and-forth moving means and the said up-and-down moving means.

  As means for moving the rack case in the front-rear direction and the up-down direction, for example, a rack is provided along the movement direction on the vehicle body side, a pinion that meshes with the rack is provided on the rack case side, and the driving force of the motor (movement motor) is used. By rotating the pinion, the rack case can be moved along the rack and stopped at an arbitrary position. Alternatively, it is possible to adopt a configuration in which a rack case can be moved along the rack by pressing or pulling and stopped at an arbitrary position by a separately provided actuator (movement actuator).

  Note that a steering mechanism using a rack and pinion mechanism or the like can be adopted for the steering of the left and right wheels by the rack bar penetrating the inside of the rack case, as in the conventional example. For example, based on information from a sensor that detects the steering angle of the steering wheel of the driver's seat, the computer (engine control unit (ECU), etc.) outputs the amount of movement of the rack bar in the left-right direction and commands the operation. The left and right wheels can be steered. In this case, the rotation by the driving force of the motor (steering motor) can be transmitted to the rack bar provided in the steering mechanism that connects the left and right wheels via the rack and pinion mechanism. Alternatively, the driving force of a separately provided actuator (steering actuator) can be transmitted to the rack bar. Thereby, the structure which can move the rack bar in a rack case to the left-right direction, and can stop at arbitrary positions is employable.

  The front-rear movement means and the vertical movement means, or any one of these configurations, can be a vehicle that is applied to at least the rack case of the rear wheel.

In each of these configurations, normal wheels can be steered by the movement of the rack bar in the left-right direction, and the rack case can be moved in the front-rear direction and the up-down direction without using a complicated mechanism. The vehicle can be moved laterally, turned around, and rotated on the spot, and various effects such as improved running stability can be exhibited.
The reason why such a function can be exhibited is that an in-wheel motor is provided on a wheel to which a rack case that can move back and forth or up and down is connected. Drive systems other than in-wheel motors, that is, drive force transmission systems (constant velocity joints) from engines and motors arranged in the hood as in the past, have a limited operating angle (usually 50 degrees (50 degrees) or less). Steering beyond 50 degrees is impossible. By providing the in-wheel motor, it is possible to realize a running pattern that cannot be achieved by a conventional mechanism such as Patent Document 4.

  In each of these configurations, it is possible to employ a configuration in which the vehicle interior is provided with a mode switching unit that switches the traveling mode of the vehicle by the front / rear moving unit and / or the vertical moving unit. This mode switching means may be, for example, a switch, lever, joystick or the like that can be operated by the driver. Further, the switch, lever, joystick, etc. may be attached to the steering or the like, or provided separately from the steering in the vehicle interior.

  In each of these configurations, it is possible to employ a configuration that assists the steering force by applying an appropriate torque from the in-wheel motor to the wheels at the time of steering. For example, when a wheel is accompanied by a movement in the plane direction at the time of turning (a state in which the wheel moves sideways along the road surface instead of turning with the wheel stopped at the place), It is desirable to use a simple configuration.

  In each of these configurations, it is possible to employ a configuration in which the movement of the rack case in the front-rear direction or the vertical direction is restricted by a lock mechanism.

  Further, in each of these configurations, during traveling in the lateral movement mode in which all the wheels are directed at right angles to the straight traveling direction of the vehicle, the steering angle of the wheels is slightly changed by the movement in the left-right direction by the rack bar. The structure to be made can be adopted.

  A description will be given of several travel modes when the steering device having these configurations is mounted on a vehicle.

  In the present invention, in the normal driving mode, it operates without a sense of incongruity with the conventional steering operation, and various driving modes such as in-situ rotation, lateral movement, and small turn are also possible. As a result, it is possible to perform lateral movement, small turn, etc. at low cost without using a complicated mechanism. That is, in the normal travel mode, the vehicle is steered only by the left and right movements by the rack bar, and in modes different from the normal travel such as the in-situ rotation (turning) mode and the lateral movement mode, the rack case is rotated by moving back and forth or up and down. Rudder.

(Normal driving mode)
The left and right wheels are simultaneously steered right or left at a predetermined angle by movement in the left-right direction by the rack bar. Specifically, the left and right wheels can be steered in the left and right direction by moving the rack bar arranged in the rack case in either the left or right direction with respect to the straight traveling direction. The rack bar can be moved left and right by a normal steering actuator or a steering operation shaft connected to a steering wheel (handle) if it is a front wheel.

  At this time, if the rack case is provided with a moving means in the front-rear direction or a moving means in the up-down direction, the above-mentioned locking mechanism is set so that the vertical movement and the forward-backward movement do not occur. Use and fix. For example, when a moving actuator is used as the moving means in the front-rear direction and the moving means in the up-down direction, it can be a locking mechanism by locking the movement of the moving actuator, or a lock provided separately By being fixed by the mechanism (restraint mechanism), it is possible to travel (e.g., forward travel) equivalent to a normal vehicle.

(In-situ rotation mode)
In the in-situ rotation mode, the rack case attached to the front and rear wheels moves in the front-rear direction or the up-down direction to steer the wheels to a predetermined angle that can be rotated in-situ. The rack case can be moved in the front-rear direction or the up-down direction, for example, by following the rotation of the wheel by the aforementioned moving actuator or in-wheel motor.

  In the in-situ rotation mode, the extension line of the center line (axle center line) of all the wheels faces the vehicle center side in plan view. For this reason, it is also possible to rotate the vehicle 360 degrees on the spot without moving the vehicle center by turning. At this time, the rack case is fixed by the lock mechanism, thereby enabling a more stable turning motion. Further, a method of fixing the movement of the rack case in the front-rear direction and the up-down direction with a steering actuator used for normal steering or a steering operation shaft connected to a steering wheel in the case of a front wheel is also conceivable.

(Lateral movement mode)
In the horizontal movement mode, the vehicle moves in the horizontal direction with the vehicle facing in the front-rear direction, that is, moves in the horizontal direction. Here, the rack case attached to the front and rear wheels moves in the front-rear direction or the vertical direction, thereby turning the wheel up to 90 degrees with respect to the straight traveling direction. The rack case can be moved in the front-rear direction or the up-down direction, for example, by following the rotation of the wheel by the aforementioned moving actuator or in-wheel motor.

In the lateral movement mode, all wheels are parallel to a direction perpendicular to the straight direction of the vehicle. That is, the center line of all the wheels (axle center line) forms a certain angle with respect to the longitudinal direction of the vehicle, and the center lines of all the wheels are parallel.
At this time, by similarly fixing the rack case by the lock mechanism, more stable movement of the vehicle becomes possible. The same is true in that it is possible to fix the movement of the rack case in the front-rear direction and the up-down direction with a steering actuator used for normal turning, or a steering operation shaft connected to the steering if it is a front wheel. .

  As a fine adjustment function, the tire angle can be finely adjusted, that is, the steering angle of the wheel can be slightly changed by a slight movement of the rack case in the left-right direction with respect to the straight traveling direction of the vehicle. This slight movement is possible by moving the rack case and the rack bar arranged in the rack case in a predetermined direction by the operation of a commonly used steering actuator.

(Turn mode)
The small turning mode is a mode in which the rear wheels and the front wheels are steered in opposite phases, and can be rotated with a smaller diameter than when only two wheels are steered. In the small turning mode, the front wheels are steered to a predetermined angle and the rear wheels are steered in the opposite phase to the front wheels by the movement of the rack bars respectively attached to the front and rear wheels. Specifically, the rack bar arranged in the rack case can be steered in the corresponding direction by moving the left and right wheels of the front wheels and the left and right wheels of the rear wheels by moving in either the left or right direction with respect to the straight direction. it can. The rack bar can be moved left and right by a steering actuator used in the normal traveling mode, or by a steering operation shaft connected to the steering if it is a front wheel. In the small turning mode, the mode is switched depending on the vehicle speed. For example, by controlling so as not to be in the small turning mode at a speed of 20 km / h or more, safe traveling is ensured.

(High speed mode)
During high-speed traveling, the toe adjustment can be performed by moving the rack case attached to the rear wheel in the front-rear direction or the up-down direction with respect to the straight direction by the front-rear movement actuator. In general, when the vehicle is traveling at high speed, the vehicle body can travel stably by using toe-in. In the high speed mode, mode switching is performed according to the vehicle speed, and for example, safe driving is ensured by performing control so as to be effective only at a speed of 80 km / h or higher.

(Danger avoidance mode)
The danger avoidance mode is a mode in which the rear wheels and the front wheels are steered to the same phase or the opposite phase to ensure a danger avoidance posture at an early stage and to improve running stability. In the danger avoidance mode, the front wheels are steered to a predetermined angle and the rear wheels are steered to the same or opposite phase as the front wheels by the movement of the rack bars respectively attached to the front and rear wheels. . Specifically, the rack bar arranged in the rack case can be steered in the corresponding direction by moving the left and right wheels of the front wheels and the left and right wheels of the rear wheels by moving in either the left or right direction with respect to the straight direction. it can. The rack bar can be moved left and right by a steering actuator used in the normal travel mode.

  By providing an in-wheel motor on the wheel connected to a rack case that can be moved back and forth or up and down, in normal driving mode, it operates without discomfort with conventional steering operation, in-situ rotation, lateral movement, small turn, etc. Various driving modes may also be possible. Further, the cost can be reduced without using a complicated mechanism or control. That is, in a vehicle (4WS) that gives a steering angle to the four wheels, the front and rear wheels can be steered to the steering angle of the same phase or opposite phase without using a complicated mechanism to cope with lateral movement and small turning. .

Image of vehicle using steering device of this embodiment The top view which shows 1st embodiment of this invention FIG. 2 is a plan view showing a lateral movement (parallel movement) mode. FIG. 2 is a plan view showing the small turn mode The top view which shows 2nd embodiment of this invention FIG. 5 is a plan view showing the small turn mode FIG. 5 is a plan view showing a lateral movement (parallel movement) mode. FIG. 5 is a plan view showing the in-situ rotation mode. FIG. 5 is a plan view showing a lateral movement (parallel movement) mode. The top view which shows 3rd embodiment of this invention FIG. 10 is a plan view showing the small turn mode FIG. 10 is a plan view showing the small turn mode

  An embodiment of the present invention will be described with reference to FIGS. In each embodiment, the in-wheel motor M is mounted in the wheel of the driving wheel of the vehicle 1 either in the front-rear direction, the left-right direction, or in all the wheels W. By providing the in-wheel motor M, various travel patterns are possible.

  FIG. 1 shows an image diagram of a vehicle 1 using the steering device of this embodiment. It shows a two-seater (side-by-side two-seat) vehicle body with ultra-compact mobility. However, the present invention is not limited to ultra-compact mobility and can also be applied to ordinary vehicles.

(First embodiment)
FIG. 2 is a schematic plan view showing a drive system and a control path of the vehicle 1 of the first embodiment. In this embodiment, the front wheel has a normal steering device in which the rack case does not move back and forth and up and down, and the rear wheel has the steering device of the present invention in which the rack case is movable back and forth and up and down. Adopted.

  In a steering device for a front wheel that is a driven wheel, a rack bar 11 that connects the left and right wheels W (FL, FR) is accommodated in a rack case (steering box) 10. Both ends of the rack bar 11 are connected to the wheels W via tie rods 12, respectively. Various members such as a knuckle arm are appropriately interposed between the tie rod 12 and the wheel W.

  In the steering device for the rear wheels, which are drive wheels, a rack bar 21 connecting the left and right wheels W (RL, RR) is divided into two in the middle, and the divided rack bar 21 is a rack case (steering box) 20. Is housed inside. Both ends of the rack bar 21 are connected to the wheels W via tie rods 22, respectively. The same is true in that various members such as a knuckle arm may be appropriately interposed between the tie rod 22 and the wheel W.

  The front wheel rack case 10 has a steering actuator 31 or a steering operation shaft connected to the steering wheel 2 if it is a front wheel. The rear wheel rack case 20 has a steering actuator 31 and a moving actuator. An actuator 32 is provided.

  In the front wheel rack bar 11, an engine control unit 40 (hereinafter referred to as an ECU 40) moves in the left-right direction of the rack bar 11 based on information from the sensor 41 that detects the steering angle of the steering 2 of the driver's seat or the steering torque. Calculates and outputs the required amount of movement or operating force. Based on the output, the actuator driver 30 commands the front-wheel steering actuator 31 to steer the left and right wheels W in the necessary direction by a necessary angle. The sensor 41 is provided on the operation shaft 3 that rotates about the axis as the steering 2 rotates.

  The front wheel steering device is not limited to the steer-by-wire system in which the steering operation performed by the driver is replaced with an electric signal and steered. For example, a general mechanism using a mechanical link (such as a rack and pinion mechanism) is used. A simple steering device can also be employed. In this case, the function of the steering actuator 31 assists by calculating a torque necessary for the movement of the rack bar 11 in the left-right direction by a steering operated by the driver, or a motor connected to the steering operation shaft.

  Further, in the rear wheel rack bar 21, the ECU 40 requires the rack bar 21 to move in the left-right direction based on information from the sensor 41, input from the mode switching means 42, or determination of the running state by the ECU 40 itself. Calculate and output the quantity. Based on the output, the actuator driver 30 commands the rear-wheel steering actuator 31 to steer the left and right wheels W in a necessary direction by a necessary angle. Similarly, the ECU 40 outputs a necessary amount of movement of the rack case 20 in the front-rear direction and the up-down direction. Based on the output, the actuator driver 30 instructs the rear-wheel movement actuator 32 to The required amount of the rack case 20 is moved.

  In normal traveling, the driver can operate the steering 2 to go straight through the front wheel steering device, turn right, turn left, and so on according to each scene.

  For example, when the ECU 40 recognizes that the vehicle 1 is traveling at a high speed, the actuator driver 30 instructs the rear wheel moving actuator 32 to move the rack case 20 backward based on the output of the ECU 40. Let As a result, the left and right wheels RL, RR of the rear wheels are in a state where the front side is slightly closed (toe-in state) relative to the parallel state, and stable high-speed traveling is possible.

  This toe adjustment may be automatically performed based on the determination of the traveling state such as the vehicle speed and the load applied to the axle by the ECU 40, or may be performed based on the input from the mode switching means 42 provided in the cab. You may be made to be. The driving mode can be switched by operating the mode switching means 42 by the driver. The mode switching means 42 may be, for example, a switch, lever, joystick, etc. that can be operated by the driver. The mode switching means 42 is also used when switching each driving mode described later.

  FIG. 3 shows that in the vehicle 1 of the first embodiment, the rear wheels are steered in the same direction as the front wheel steering direction by the steering actuator 31 (in the figure, both the front and rear wheels are steered to the right). Therefore, it is possible to run diagonally for the purpose of avoiding danger. In the oblique running, the vehicle can be moved in the lateral direction (parallel movement) such as a lane change while the vehicle is directed in the front-rear direction or hardly changed in direction. This operation makes it possible to avoid danger from obstacles ahead.

  Here, as the moving actuator 32, for example, an actuator constituted by a linear motion mechanism such as a motor, a gear, and a ball screw can be employed. By this moving actuator 32, the rack case 20 can be moved in the front-rear direction or the vertical direction with respect to the vehicle body.

  In this embodiment, the movement actuator 32 serves as both the vertical movement means and the front-rear movement means of the rack case 20, but the vertical movement means and the front-back movement means may be provided separately. Further, if necessary, either one of the vertically moving means and the forward / backward moving means may be provided, and the other may be omitted. This is the same for the corresponding rack cases 10 and 20 in each embodiment described later.

  Further, as the steering actuator 31, one constituted by a linear motion mechanism such as a rack and pinion, a motor, a worm gear and the like can be adopted. By this steering actuator 31, the rack bar 21 in the rack case 20 can be moved in the left-right direction with respect to the vehicle body.

  Similarly, FIG. 4 shows that in the vehicle 1 of the first embodiment, the left and right wheels RL and RR of the rear wheels are steered in opposite phases by largely moving the rack case 20 of the rear wheels forward by the moving actuator 32. doing. The left and right wheels RL and RR of the rear wheels are in a state where the rear side is largely closed in a plan view.

  If the in-wheel motor M for the rear wheels is driven in this state, the vehicle 1 can make a small turn around the intersection of the respective wheel center lines (axle center lines) of the rear wheels. Here, since the intersection of the respective wheel center lines of the rear wheels is set at the center of the left and right wheels FL, FR of the front wheels, the small turning is smooth.

(Second embodiment)
FIG. 5 shows a second embodiment. In this embodiment, the front wheels and the rear wheels are drive wheels, and the steering device of the present invention is employed in which the rack cases 10 and 20 are movable forward and backward and vertically, respectively.

  In the rack bar 11 of the front wheel, the ECU 40 calculates and outputs a necessary amount of operation of the rack bar 11 in the left-right direction based on information from the sensor 41. Based on the output, the actuator driver 30 commands the front-wheel steering actuator 31 to steer the left and right wheels W in the necessary direction by a necessary angle.

  Further, in the rack case 10 of the front wheel, the ECU 40 needs to move in the front-rear direction and the vertical direction of the rack case 10 based on information from the sensor 41, input from the mode switching means 42, or judgment of the running state by the ECU 40 itself. Based on the output, the actuator driver 30 moves the rack case 10 of the front wheels through the moving actuator 32 by a necessary amount.

  The steering device for the front wheels is not limited to the steer-by-wire system, and a general steering device using a mechanical link (such as a rack and pinion mechanism) can be employed. In this case, the function of the steering actuator 31 is exhibited by the steering operated by the driver or the motor connected to the operation shaft of the steering.

  Also in the rear-wheel rack case 20, the ECU 40 moves in the front-rear direction and the vertical direction of the rack case 20 based on information from the sensor 41, input from the mode switching means 42, or determination of the running state by the ECU 40 itself. Is output, and the actuator driver 30 moves the rack case 20 of the rear wheel through the actuator 32 for movement based on the output.

  FIG. 6 shows the driving force of the in-wheel motor M included in each of the four wheels in the vehicle 1 according to the second embodiment in which the front wheels and the rear wheels are steered in opposite phases by the respective steering actuators 31. Indicates a state in which a small turn is possible. The control method of the steering actuator 31 and the movement actuator 32 is the same as that of the above-mentioned embodiment.

  FIG. 7 similarly shows a state in which the vehicle 1 according to the second embodiment enables the vehicle to run diagonally by turning the front wheels and the rear wheels in the same phase. In this travel mode, the stability of the vehicle body can be ensured during unstable travel such as when avoiding danger.

  FIG. 8 shows a vehicle 1 according to the second embodiment in which the front rack case 10 is largely moved backward by the moving actuator 32 and the rear rack case 20 is moved by the moving actuator 32 (the amount of movement of the front wheel). This shows a state in which the rack case 10 has moved forward by the same distance as the rearward movement amount of the rack case 10 from the steady position.

  In this state, in-situ rotation with the center of the vehicle as the turning center can be performed by the driving force of the in-wheel motor M included in each of the four wheels. At this time, it is not always necessary to drive all the in-wheel motors M, and some in-wheel motors M may be driven as necessary.

  Similarly, FIG. 9 shows a vehicle 1 according to the second embodiment, in which the front wheel rack case 10 is further moved backward by the moving actuator 32, and the rear wheel rack case 20 is moved by the front wheel front / rear moving actuator. A state in which the front wheel has moved forward by the same distance as the distance from the steady position of the rack case 10 to the rack case 10 is shown.

  Thus, all the steering angles of the wheels are set to 90 degrees (90 degrees with respect to the straight traveling direction), and in this state, the lateral movement (parallel movement) is performed by the driving force of each in-wheel motor M included in each of the four wheels. It becomes possible. Also in this case, it is not always necessary that all in-wheel motors M are driven, and some in-wheel motors M may be driven as necessary, but at least one of the left and right front wheels, and It is desirable that either the left or right side of the rear wheel is driven.

(Third embodiment)
FIG. 10 shows a third embodiment. In this embodiment, as in the first embodiment, the front wheel is provided with a normal steering device in which the rack case 10 does not move back and forth and up and down, and the rack case 20 is movable back and forth and up and down on the rear wheel. A certain steering device of the present invention is employed.

  Further, in this embodiment, in a straight traveling state, the rear wheel steering device (the rack bar 21, the rack case 20, etc.) has a coupling point between the wheel W and the tie rod 22 (when a knuckle arm is used, the knuckle arm and the tie rod 22 It is located behind the connection point). By arranging in this way, there is an advantage that the interior space can be widened.

  As a modification of this embodiment, if a steering device that is movable back and forth and up and down is mounted on the front wheels, it is opposite to the case of the rear wheels, and the steering device is a coupling point between the wheels W and the tie rods 12. It will be located in front of.

  FIG. 11 shows the vehicle 1 according to the third embodiment, in which the rear wheel rack case 20 is moved forward by the moving actuator 32 to steer the left and right wheels RL and RR to opposite phases. Yes. If the in-wheel motor M is driven in this state, the vehicle 1 can make a small turn around the intersection of the respective wheel center lines (axle center lines) of the rear wheels. Here, since the intersection of the respective wheel center lines of the rear wheels is set at the center of the left and right wheels FL, FR of the front wheels, the small turning is smooth.

  FIG. 12 similarly shows a state in which the vehicle 1 of the third embodiment is capable of making a small turn by turning the rear wheels in opposite phases with respect to the front wheels.

(Switching operation mode)
In each of these embodiments, the operation mode set in each embodiment can be switched in addition to the normal travel mode by operating the mode switching means 42 in the passenger compartment during each operation mode. Specifically, it is possible to select a normal traveling mode, an in-situ rotation mode, a lateral movement mode, a small turn mode, and the like. If switching can be performed by a switch operation or the like, safer operation is possible.

  For example, when the mode switching means 42 is operated and the in-situ rotation mode is selected (however, only in the embodiment in which the in-situ rotation mode is set), the rack is arranged so that the center of the vehicle 1 has the center of rotation. The four wheels can be steered only by moving the cases 10 and 20 in the front-rear direction. At this time, the movement of the rack bars 11 and 21 in the left-right direction and the movement of the rack cases 10 and 20 in the vertical direction are restricted, and the operation can be simplified and stable rotation is enabled.

  Further, if the mode switching means 42 is operated to select the lateral movement mode (however, only in the embodiment in which the lateral movement mode is set), the rack is set so that the steering angle of the four wheels becomes 90 degrees. The cases 10 and 20 can be steered only by moving in the front-rear direction. During the movement of the rack cases 10 and 20 in the front-rear direction, the movement of the rack bars 11 and 21 in the left-right direction and the movement of the rack cases 10 and 20 in the vertical direction are restricted. If the rudder angle of the four wheels is 90 degrees, the front and rear and vertical movements of the rack cases 10 and 20 are fixed, the left and right restraints of the rack bars 11 and 21 are released, and only the left and right movements are performed. Finely adjust the rudder angle of the wheel W. By controlling in this way, the wheel W can be easily positioned and steered even during lateral movement.

  Furthermore, if the mode switching means 42 is operated and the normal traveling mode is selected, after the toe adjustment is performed by moving the rack cases 10 and 20 in the front-rear direction and the vertical direction according to the traveling conditions, the rack cases 10 and 20 Movement in the front / rear / up / down direction is restricted, and control is performed according to the speed range. For example, in the high speed range, the front wheels and the rear wheels are steered only in the same phase to enable stable running. On the other hand, in the low speed range, the front wheels and the rear wheels can be set so that they can be steered only in opposite phases and can turn slightly.

  The various operation modes described above are examples, and besides these, various controls using these mechanisms are possible.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Steering 3 Operation shaft 10, 20 Rack case 11, 21 Rack bar 12, 22 Tie rod 30 Actuator driver 31 Steering actuator 32 Moving actuator 40 Engine control unit (ECU)
41 Sensor 42 Mode switching means W Wheel

Claims (9)

  Rack bars that pass through the rack case are connected to the left and right wheels of the front and rear wheels via tie rods, and the rack bar can steer the left and right wheels by moving in the left-right direction with respect to the straight traveling direction of the vehicle. A vehicle comprising: a front-rear moving means for moving the rack case in the front-rear direction; and a four-wheel steering mechanism having an in-wheel motor on each wheel to which the rack bar is connected via a tie rod.   Rack bars that pass through the inside of the rack case are connected to the left and right wheels of the front and rear wheels via tie rods, and the rack case can steer the left and right wheels by moving in the left-right direction with respect to the straight traveling direction of the vehicle. There is provided a vehicle including a vertical movement means for moving the rack case in the vertical direction, and a four-wheel steering mechanism having an in-wheel motor on each wheel to which the rack bar is connected via a tie rod.   The vehicle equipped with the four-wheel steering mechanism according to claim 1, further comprising vertical movement means for moving the rack case in the vertical direction.   The four-wheel steering mechanism according to any one of claims 1 to 3, wherein the front-rear moving means and the vertical movement means, or any one of them, is applied to at least the rack case of the rear wheel. Vehicle.   5. The four-wheel drive according to claim 1, further comprising a mode switching unit that switches a traveling mode of the vehicle by the front / rear moving unit and / or the vertical moving unit or any one of them in a vehicle interior. A vehicle with a rudder mechanism.   The vehicle having the four-wheel steering mechanism according to any one of claims 1 to 5, wherein the steering force is assisted by giving an appropriate torque from the in-wheel motor to the wheel during the steering. .   The vehicle equipped with the four-wheel steering mechanism according to any one of claims 1 to 5, wherein the wheel is steered by applying only an appropriate torque from the in-wheel motor to the wheel at the time of steering. .   The vehicle provided with the four-wheel steering mechanism according to any one of claims 1 to 7, wherein movement of the rack case in the front-rear direction or the vertical direction is restricted by a lock mechanism.   During traveling in the lateral movement mode in which all the wheels are directed in a direction perpendicular to the straight direction of the vehicle, the steering angle of the wheels can be slightly changed by the movement in the left-right direction by the rack bar. A vehicle comprising the four-wheel steering mechanism according to any one of claims 1 to 8.

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