JP6437189B2 - Steering device and steering device system - Google Patents

Description

  The present invention relates to a steering device that steers wheels and a steering device system that uses the steering device.

  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.

  For example, the steering mechanism described in Patent Document 1 includes a steering link mechanism for left and right wheels using a tie rod and a knuckle arm on at least one of the front wheel side and the rear wheel side, and the tie rod length, the distance between the left and right tie rods, or By providing an actuator that changes one of the angles formed by each wheel and the knuckle arm, smooth running performance and responsiveness are ensured for normal running, parallel movement, and small turn.

  Further, the steering mechanism described in Patent Document 2 is disposed between the left and right wheels of the front and rear wheels, and is provided between a steering shaft that can rotate around an axial center and the steering shaft divided into left and right parts. Forward / reverse switching means for switching the rotation direction of the steering shaft in the forward / reverse direction, thereby enabling movement such as a steering angle of 90 degrees and lateral movement.

  Further, in the four-wheel steered vehicle described in Patent Document 3, the actuator is operated in accordance with the steering of the front wheel to steer the rear wheel. Further, the steering mechanism described in Patent Document 4 includes a traveling mode switching unit that switches between a normal traveling mode and an unusual traveling mode such as a small turning operation by a driver operating a button.

Japanese Patent Laid-Open No. 04-262971 Japanese Patent No. 4635754 Utility Model Registration No. 2600374 JP2013-112103A

  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. In addition, the structure of 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 perform lateral movement (90-degree steering) with this mechanism alone for the same reason described above.

  Further, in the configuration of Patent Document 4, switching between the normal driving mode and the non-normal driving mode is performed by the driver operating a button provided in the driving mode switching means, and by this button operation, Corresponding to the travel mode of the operated button, the wheels are automatically steered so as to be in the mode position. During this automatic turning, for example, if the wheel touches an obstacle such as a curb and the turning motor detects an abnormal signal (error) as an overload condition, the operation stops or the overload condition is resolved. The wheel can be steered in the opposite direction to the position to be operated. However, since these operations are automatically performed regardless of the driver's judgment (steering operation), a driver who cannot participate in the avoidance operation in an abnormal state may feel anxiety.

  Therefore, the present invention enables a vehicle that gives a steering angle to four wheels to cope with lateral movement, small turning, etc. without using a complicated mechanism, and is abnormal when switching between the normal travel mode and the special travel mode. It is an object to enable a driver to be involved in avoiding an abnormal state when a state occurs.

  In order to solve the above problems, in the present invention, tie rods connected to left and right wheels and steering the left and right wheels, a pair of rack bars respectively connected to the tie rods of the left and right wheels, and the pair of rack bars And a synchronous gear that converts the movement of one rack bar in one direction relative to the parallel direction of the rack teeth into the other direction of the other rack bar, and the steering operation by the driver, the pair of racks The steering apparatus includes a rack bar operating means capable of moving the bar in the opposite direction along the parallel direction of the rack teeth of each rack bar.

  By connecting the wheels to the pair of rack bars that can be moved independently from each other via tie rods, the pair of rack bars can be fixed together in normal driving mode and operated without any sense of incongruity with conventional steering operations. By moving the pair of rack bars in different directions, various special driving modes such as small turn, spot rotation, and lateral movement can be realized.

  Further, by using a pair of rack bars that can be switched between separation and fixation, the cost can be reduced without using complicated mechanisms and controls. That is, in a vehicle that gives a steering angle to the four wheels, the front and rear wheels can be steered to the same or opposite phase steering angle without using a complicated mechanism, and can respond to lateral movement and small turns.

  In this configuration, the operation means of the rack bar engages with the pair of rack bars, respectively, and synchronizes the movement of one rack bar in one direction with respect to the parallel direction into the movement of the other rack bar in the other direction. It can be equipped with gears.

  The rack bar may include a synchronization rack gear that meshes with the synchronization gear, and a steering rack gear that receives a driving force for moving the one rack bar in the parallel direction.

  The rack bar may be formed by integrally forming the synchronization rack gear and the steering rack gear, but the synchronization rack gear and the steering rack gear formed separately are fixed integrally. If it is, the manufacture is easy.

  In addition to the operation in the normal travel mode, the special rack mode (spot rotation, lateral movement) is performed by moving the pair of rack bars in opposite directions along the parallel direction of the rack teeth of each rack bar. When the wheel angle is changed to), it is possible to give a sense of security in operation by turning the wheel by the driver's steering operation. This is because, for example, when the driver senses an abnormal condition such as the wheel touching an obstacle such as a curb and the steering operation becomes heavy, the steering operation is stopped or the steering is returned at the discretion of the driver. This is because it is allowed to quickly avoid the abnormal state.

  In the above configuration, the synchronous gear box that holds at least one of the synchronous gears and is movable in the left-right direction, the rack case that holds the pair of rack bars and is fixed to the vehicle frame side, and the rack case On the other hand, a fixing mechanism that can fix the synchronous gearbox is further provided, and when the pair of rack bars are moved in opposite directions, the synchronous gearbox is fixed by the fixing mechanism. it can.

  In this way, when the pair of rack bars are moved in the opposite direction, that is, when the left and right wheels are steered in the opposite direction, the synchronous gear box is fixed to the rack case fixed to the vehicle frame side. As a result, the pair of rack bars can be moved in the opposite direction by the same distance even if there is a difference in the inclination of the ground contact surface of the tire or the friction state.

  That is, for example, even when the friction force between the left wheel and the ground contact surface is larger than the friction force between the right wheel and the contact surface, the rack bar connected to the left wheel does not move and is connected to the right wheel. There is no situation where only the rack bar moves greatly. For this reason, the left and right wheels can be quickly set to the target wheel angle, and the steering angle control can be stably performed.

  In the configuration in which the fixing mechanism is provided, it is preferable that the synchronous gear box is fixed at the position of the synchronous gear box when the vehicle is traveling straight. Further, in each of the above configurations, the fixing mechanism is fixed when the synchronous gear box is moved in the opposite direction along the parallel direction of the teeth of the rack bar. It is preferable to do this. Further, the rack bar operating means couples or separates the first pinion gear meshing with the one rack bar, the second pinion gear meshing with the other rack bar, and the rotation shafts of the first and second pinion gears. It is preferable to have a structure including a connecting mechanism.

  The steering device that is operated by a steering operation of the driver and steers the front wheels, the steering actuator that operates in conjunction with the steering operation, and the rear wheels that are steered in accordance with the operation of the steering actuator A steering device system including the steering device can also be configured.

  By connecting the wheels to the pair of rack bars that can be moved independently from each other via tie rods, the pair of rack bars can be fixed together in normal driving mode and operate without a sense of incongruity with conventional steering operations. By moving the paired rack bars in different directions, various special driving modes such as small turn, spot rotation, and lateral movement can be realized. Further, by using a pair of rack bars that can be switched between separation and fixation, the cost can be reduced without using complicated mechanisms and controls. That is, in a vehicle that gives a steering angle to 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 a small turn or a lateral movement.

  Moreover, not only the operation in the normal driving mode but also when changing the wheel angle to the special driving mode (spot rotation, lateral movement), the wheel is steered by the steering operation of the driver, so that the operation is safe. A feeling can be given. For example, when the driver senses an abnormal state such as the wheel touching an obstacle such as a curb and the steering becomes heavy, by stopping the steering operation at the driver's judgment or returning the steering, Since an abnormal state can be avoided promptly, an effect of increasing the driver's sense of security can be expected.

Image of vehicle using steering device of this embodiment 1 shows a first embodiment of the present invention, (a) is a plan view of a general vehicle, (b) is a plan view of a steer-by-wire vehicle. The top view which shows normal driving mode (normal steering mode) in the vehicle of Fig.2 (a) FIG. 2A is a plan view showing a small turn mode in the vehicle of FIG. The top view which shows the spot rotation mode in the vehicle of Fig.2 (a) FIG. 2A is a plan view showing a lateral movement (parallel movement) mode in the vehicle of FIG. Sectional view showing the support state of the wheel The perspective view which shows the external appearance of a steering device The detail of the rack bar operation | movement means of a steering device is shown, (a) is a front view of a separation state, (b) is a front view of a coupling state Plan view showing the inside of the steering device Front view showing the inside of the steering device The inside of a steering device is shown, (a) is a top view in a state where a pair of rack bars are closest, (b) is a plan view in a state where a pair of rack bars is opened

  An embodiment of the present invention will be described with reference to the drawings. In the embodiment, an in-wheel motor M is mounted in the front and rear, left and right wheels w of the steering device for driving wheels of the vehicle 1. 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. The vehicle 1 can steer the wheels w through the steering shaft 3 by operating the steering 2. However, the present invention is not limited to ultra-compact mobility and can also be applied to ordinary vehicles.

  FIG. 2 is a schematic plan view showing a drive system and a control path of the vehicle 1 according to the embodiment of the present application. In this embodiment, the steering devices 10 and 20 of the present application are connected to the left and right wheels (FL and FR) of the front wheels and the left and right wheels (RL and RR) of the rear wheels via tie rods 12 and 22, respectively.

  A steering device for a front wheel according to the present application is a general vehicle having a steering shaft (see (a) in this figure) or a steer-by-wire type vehicle having an actuator such as a motor that is operated by a rotating operation of the steering (this figure ( b) can be employed for any of the above, and normal turning is possible by operating a pinion gear shaft linked to the steering device for the front wheels. In addition, the rear wheel steering device operates like a front wheel by operating a pinion gear shaft linked to the rear wheel steering device by an actuator (steer-by-wire) such as a motor that is operated by a rotating operation of the steering wheel. Rudder is possible. This steering device for the rear wheels can be employed in any type of vehicle shown in FIGS.

  In this figure, a vehicle equipped with a four-wheel steering mechanism that employs steering devices 10 and 20 for both the front and rear wheels is shown, but the steering devices 10 and 20 are mounted only on either the front wheels or the rear wheels, or The steering device 20 according to the present application may be provided only on the rear wheels, and the front wheels may be provided with a normal general steering device.

  Each of the steering devices 10 and 20 for the front wheels and the rear wheels is provided with two rack bars for turning the left and right wheels w. Hereinafter, for both the front and rear wheels, the rack bar connected to the left wheel w with respect to the front-rear direction of the vehicle is the first rack bar 53, and the rack bar connected to the right wheel w is the second rack bar 54. Called. Note that the direction indicated by the arrow pointing left in FIG. 2 is the forward direction of the vehicle. The same applies to FIGS. 3 to 6 later. As shown in FIG. 10 and the like, a synchronous gear 55 that meshes with each rack bar 53, 54 is provided between the two rack bars 53, 54. The synchronous gear 55 is held by a synchronous gear box 66 as shown in FIG.

  The connecting members 11 and 21 of the rack bars 53 and 54 are connected to the left and right wheels w of the front wheel or the rear wheel via tie rods 12 and 22, respectively. Various members such as a knuckle arm are appropriately interposed between the tie rods 12 and 22 and the wheel w.

  FIG. 7 shows a connection state between the wheel w in which the in-wheel motor M is accommodated and the tie rods 12 and 22. All the wheels w can be steered with the kingpin axis P connecting the center line of the ball joint BJ provided at the tip of the upper arm UA and the lower arm LA supported by the vehicle frame as the central axis. Yes. In the in-wheel motor M, the motor unit 101, the speed reducer 102, and the wheel bearing 103 are arranged in series in this order from the inner side of the vehicle body toward the wheel w.

  As shown in FIG. 8, the first rack bar 53 and the second rack bar 54 are rack cases (steering cylinders) 50 that extend in the left-right direction with respect to the straight traveling direction (front-rear direction) of the vehicle. Is housed inside. The rack case 50 is supported by a frame (chassis) (not shown) of the vehicle 1.

  The rack case 50 can be supported on the vehicle 1 by, for example, screw fixing directly or indirectly to the frame of the vehicle 1 via a flange portion 50a provided on the rack case 50.

  The first rack bar 53 and the second rack bar 54 can move in the same direction in the same direction in the left-right direction in the rack case 50 with respect to the straight traveling direction of the vehicle. This operation is performed by the operation of the normal steering actuator 31 based on the operation of the steering 2 performed by the driver. With this operation, the left and right wheels can be steered in the same direction on the left and right during normal travel.

  The pinion gear shaft 61 shown in FIG. 9 is a steering shaft 3 (in the case of a general vehicle (see FIG. 2A)) or an actuator 31 such as a motor that is operated by the rotational operation of the steering 2 (in the case of the steer-by-wire system ( 2))). The pinion gear shaft 61 has a first pinion gear 62 that is integrally or integrally rotatable. The first rack bar 53 meshed with the first pinion gear 62 and the second pinion gear 65 are meshed with each other. Two rack bars 54 are provided. The two rack bars 53 and 54 extend in parallel to each other.

  In addition, a coupling mechanism 63 is provided that allows the first pinion gear 62 and the second pinion gear 65 to be coupled and separated in the rotational direction. FIG. 9A shows a separated state, and FIG. 9B shows a joined state.

  Further, as shown in FIG. 10, each of the steering devices 10 and 20 includes a rack bar operating means 60. The rack bar operating means 60 moves the first rack bar 53 and the second rack bar 54 in directions opposite to each other along the left-right direction with respect to the straight traveling direction of the vehicle, that is, the direction in which the rack extends and contracts (the direction in which the rack teeth are parallel). It has the function of moving the same distance in the opposite direction.

  As shown in FIG. 10, the rack bar operating means 60 is a rack gear of the pair of rack bars 53, 54 facing each other, that is, the synchronization rack gear 53a of the first rack bar 53 and the synchronization rack gear 54a of the second rack bar 54. Are provided with first synchronization gears 55 that mesh with each other.

  The first synchronization gear 55 includes three gears 55a, 55b, and 55c arranged in parallel at a constant interval along the parallel direction of the rack teeth of the rack bars 53 and 54. While the first and second pinion gears 62 and 65 are separated from each other by the coupling mechanism 63 shown in FIG. 9, the first rack bar 53 is driven by the driving force input from the rack bar operating means 60. Is moved in one direction with respect to the parallel direction, the movement is converted into a movement in the other direction of the second rack bar 54.

  As shown in FIG. 11, the steering devices 10 and 20 are provided with a fixing mechanism 67 that fixes the synchronous gear box 66 to the rack case 50. The fixing mechanism 67 employs a structure in which, for example, the trapezoidal screw 68 is rotated by a synchronous gearbox fixing actuator 69 (motor) that operates the trapezoidal screw 68, and the presser portion 68 a is pressed against and fixed to the synchronous gearbox 66. Can do. In this embodiment, the case where the trapezoidal screw 68 is used as the fixing mechanism 67 is shown, but other actuators such as a push-pull solenoid may be used.

  Since the four flange portions 50a of the rack case 50 are screwed to the frame of the vehicle body, when the rack case 50 and the synchronous gear box 66 are fixed by the fixing mechanism 67, the synchronous gear box 66 is attached to the frame. On the other hand, it is fixed. Further, by fixing the synchronous gear box 66 and the rack case 50 relative to each other in a straight traveling state of the vehicle body, not only in the straight traveling state but also in any angle operation of the steering wheel 2, The rudder angle can be made the same.

  10 and 11, gears 56a and 56b constituting the second synchronization gear 56 are arranged between the adjacent gears 55a and 55b of the first synchronization gear 55 and between the gears 55b and 55c, respectively. Has been. The second synchronization gear 56 meshes only with the first synchronization gear 55 without meshing with the synchronization rack gear 53 a of the first rack bar 53 or the synchronization rack gear 54 a of the second rack bar 54. The second synchronization gear 56 is for moving the three gears 55a, 55b, 55c of the first synchronization gear 55 in the same direction by the same angle. By the second synchronization gear 56, the first rack bar 53 and the second rack bar 54 can smoothly move relative to each other.

  As shown in FIG. 9, the first rack bar 53 and the second rack bar 54 include steering rack gears 53b and 54b, respectively, in addition to the synchronization rack gears 53a and 54a.

  The first rack bar 53 and the second rack bar 54 are obtained by integrally fixing the synchronizing rack gears 53a and 54a and the steering rack gears 53b and 54b, respectively, by fixing means such as a bolt shaft. As good as

  The steerable rack gears 53b and 54b function as a driving force input means for moving the rack bars 53 and 54 along the parallel direction of the rack teeth with respect to the frame of the vehicle 1.

  In order for the first rack bar 53 to move from the state shown in FIG. 12A (straight forward state) to the state shown in FIG. After the mechanism 63 is separated, the first rack bar 53 is moved in one direction by the input of the driving force from the rack bar operating means 60. Then, the force is transmitted to the second rack bar 54 via the first synchronization gear 55 meshed with both the first rack bar 53 and the second rack bar 54, Move the same distance in the opposite direction as the first rack bar.

  In the straight traveling state (see FIG. 12A), the first pinion gear 62 and the second pinion gear 65 are rotationally fixed by the coupling mechanism 63 meshing at the tire (rack bar) position in the straight traveling state. When the steering shaft 2 is rotated by rotating the steering 2, the first rack bar 53 and the second rack bar 54 move in the same direction in the rack case 50 attached to the frame in the same direction and to the left and right.

  Further, in the state of the lateral movement mode (see FIG. 12B), the coupling mechanism 63 is separated, and the first rack bar 53 and the second rack bar 54 are engaged with the synchronous gear 55 in the synchronous gear box 66, respectively. doing. The meshing of the synchronization gear 55 causes the rack bars 53 and 54 to move in the opposite direction with respect to the synchronization gear box 66. Here, if the synchronous gear box 66 is fixed to the rack case 50 fixed to the frame, the synchronous gear box can be used even if the ground contact surfaces of the left and right wheels w (tires) are inclined or have different frictional states. With respect to 66, the pair of rack bars 53, 54 can be moved by the same distance in opposite directions. Therefore, the left and right wheels w connected to the rack bars 53 and 54 via the tie rods 12 and 22 are always moved (steered) at the same angle.

  In this lateral movement mode, the first pinion gear 62 is rotated by a steering operation based on the judgment of the driver. That is, when the driver senses an abnormal state such as the wheel w touching an obstacle such as a curb during steering operation, and the steering operation becomes heavy, the steering operation is stopped or the steering is performed based on the determination. The abnormal state can be avoided promptly. In this way, when the rack bars 53 and 54 move in the other direction, by allowing the driver to participate in the operation for changing the mode, the driver cannot perform any operation during the mode changing operation. , Can give a sense of security in operation.

  By operating the mode switching actuator 32 provided in the steering device 10 instead of moving the rack bars 53 and 54 in the other directions and changing to the lateral movement mode by performing the steering operation in this way, the driver operates the mode switching actuator 32. The rack bars 53 and 54 can be controlled to move.

  Next, the operation of the rack bar operating means 60 will be described.

  The rack bar operation means 60 of the front-wheel steering device 10 includes a first rotation shaft (pinion gear shaft) 61 that directly rotates in accordance with the rotation operation of the steering 2 performed by the driver (see FIG. 9). Thus, instead of directly rotating the first rotating shaft 61 in accordance with the rotation operation of the steering wheel 2 performed by the driver, the driving of the mode switching actuator 32 that operates in conjunction with the rotation operation of the steering wheel 2 performed by the driver. It is also possible to switch so that rotation is transmitted to the first rotating shaft 61 side by force or by the driving force of the mode switching actuator 32 that operates in conjunction with the operation of the mode switching means 42 provided in the vehicle 1.

  The rack bar operation means 60 of the steering device 20 for the rear wheels is also the mode switching means provided in the vehicle 1 by the driving force of the mode switching actuator 32 that operates in conjunction with the rotational operation of the steering 2 performed by the driver. And a first pinion gear 62 that is attached to the first rotation shaft 61 so as to be integrally rotatable with the first rotation shaft 61. Rotation is transmitted from the operating shaft of the mode switching actuator 32 to the first rotating shaft 61 side via the steering shaft 3 (see FIG. 9).

  The rack bar operation means 60 includes a first pinion gear 62 integrated with or coupled to the first rotation shaft 61, a second rotation shaft 64 arranged on the same straight line as the first rotation shaft 61, and the second rotation shaft. A second pinion gear 65 is attached to 64 so as to be integrally rotatable.

  FIG. 8 is an external perspective view showing the entire steering devices 10 and 20. A first rack bar 53 and a second rack bar 54 are accommodated between the front cover 52 and the rear cover 51. Although not shown in the drawings, boots are provided for preventing foreign substances from entering the movable portion from the attachment portions of the tie rods 12 and 22 to the rack case 50 (the case front portion 51 and the case rear portion 52). The first rotating shaft 61 is connected to the operating shaft of the mode switching actuator 32 via a steering joint (not shown).

  As shown in FIG. 9, the first pinion gear 62 meshes with the steering rack gear 53 b of the first rack bar 53, and the second pinion gear 65 meshes with the steering rack gear 54 b of the second rack bar 54. ing.

  Further, a coupling mechanism 63 that can be coupled and separated from each other is provided between the first pinion gear 62 and the second pinion gear 65. The coupling mechanism 63 has a function of switching the first rotating shaft 61 and the second rotating shaft 64 between a state in which relative rotation is possible (separated state) and a state in which relative rotation is impossible (coupled state).

  As shown in FIG. 9, the coupling mechanism 63 includes a fixed portion 63 b on the second rotating shaft 64 side and a moving portion 63 a on the first rotating shaft 61 side. The moving part 63a is pressed against the fixed part 63b side by an elastic member such as a spring (not shown), and the convex part 63c on the moving part 63a side is coupled to the concave part 63d on the fixed part 63b side of the coupling mechanism 63. The shafts 61 and 64 are integrally rotatable. Note that the projections 63c may be provided on the fixed portion 63b side, and the recesses 63d may be provided on the moving portion 63a side, with the concave / convex forming portions reversed.

  By moving the moving part 63a in the axial direction with respect to the fixed part 63b of the connecting mechanism 63 by an external input from a driving source such as a push solenoid (not shown), the connection between the fixed part 63b and the moving part 63a is separated. The first rotating shaft 61 and the second rotating shaft 64 can rotate independently. That is, the first pinion gear 62 and the second pinion gear 65 can rotate independently (the separated state). FIG. 9A shows a separated state of the coupling mechanism 63, and FIG. 9B shows a coupled state thereof.

  When the first pinion gear 62 and the second pinion gear 65 are capable of relative rotation due to the separation of the coupling mechanism 63, the first pinion gear 62 is engaged with the first rack bar 53, and the second pinion gear 65 is engaged with the second rack. It meshes with the bar 54. Further, the first rack bar 53 and the second rack bar 54 are engaged with each other by a first synchronization gear 55. For this reason, with the rotation input to the first pinion gear 62, the first rack bar 53 moves in the lateral direction (one direction) along the parallel direction of the rack teeth, that is, the left-right direction of the vehicle. When the first rack bar 53 moves in the lateral direction, the first synchronization gear 55 rotates, and the second rack bar 54 moves in the opposite direction (the other direction) from the first rack bar 53 by the same distance. At this time, the second pinion gear 65 is freely rotated by the movement of the second rack bar 54.

  In this way, by switching the first pinion gear 62 and the second pinion gear 65 between the coupled state and the separated state by the coupling mechanism 63, the pair of rack bars 53, 54 are integrally moved in the left-right direction by the same distance, It is possible to easily switch to the state of moving the same distance in the opposite direction separately.

  That is, the coupling mechanism 63 is linked to the rotation operation of the steering 2 performed by the driver in a state where the first rack bar 53 and the second rack bar 54 are coupled via the first pinion gear 62 and the second pinion gear 65. By moving the first rack bar 53 and the second rack bar 54 integrally in the same direction in the left-right direction with respect to the straight traveling direction of the vehicle by the driving force of the normal steering actuator 31 that operates in the same manner, Can be steered in the same direction around the kingpin axis P (see FIG. 7). At this time, since the first rack bar 53 and the second rack bar 54 move together, the first synchronization gear 55 does not rotate.

  Further, in a state where the coupling mechanism 63 separates the first pinion gear 62 and the second pinion gear 65, that is, in a mode switching state, the first rack bar 53 and the second rack bar 54 are moved to the left and right with respect to the straight traveling direction of the vehicle. By moving each in the opposite direction, the left and right wheels can be steered in opposite directions around the kingpin axis P (see FIG. 7), that is, in directions opposite to each other. The rotation of the first pinion gear 62 is normally performed directly by the rotation operation of the steering wheel 2 performed by the driver, but the driving force of the mode switching actuator 32 that operates in conjunction with the rotation operation of the steering wheel 2 performed by the driver. Can also be done. Even when the mode switching is performed by the mode switching actuator 32, the driver can be involved in the mode switching by a steering operation.

  Furthermore, the normal steering actuator 31 can also serve as the mode switching actuator 32. That is, the normal steering actuator 31 may input rotation to the first rotating shaft 61 via the steering shaft 3 at the time of mode switching.

  Further, the mode switching actuator 32 can also serve as the driving force of the in-wheel motor M disposed on the left and right of the steering. Furthermore, it is possible to steer using any one of these normal steering actuator 31, mode switching actuator 32, left and right in-wheel motors M, or some steering operation force.

  Hereinafter, several driving modes when the steering device having each of these configurations is mounted on a vehicle will be described.

(Normal driving mode)
2A and 2B, the first rack bar 53 and the second rack bar 54 held by the rack case 50 of the front wheel steering device 10 can be moved integrally, that is, 9, the first pinion gear 62 and the second pinion gear 65 are coupled to each other by a coupling mechanism 63 capable of coupling or separation. Then, the pair of rack bars 53 and 54 in the rack case 50 attached to the vehicle frame moves in the same direction on the left and right by the same distance.

  When the steering device 10 is moved in the left-right direction with respect to the straight traveling direction by the driving force of the normal steering actuator 31 or the operation of the steering 2, the first rack bar 53 and the second rack bar 54 are also the same distance in the same direction. As shown in FIG. 3, the left and right wheels w of the front wheels are steered to a predetermined angle. FIG. 3 shows the case of turning to the right. That is, by making the two rack bars 53 and 54 fully operable by the connecting mechanism, it is possible to travel equivalent to a normal vehicle. In the normal travel mode, the driver can operate the steering 2 through the front wheel steering device 10 to make a straight turn, right turn, left turn, and other necessary turning according to each scene.

(Turn mode)
The small turning mode is shown in FIG. In addition to the operation of the front-wheel steering device 10 shown in FIG. 3, the first rack bar 53 and the second rack bar 54 in the rack case 50 of the rear-wheel steering device 20 can be moved in the same direction by the same distance. Nine connecting mechanisms 63 are connected. As with the front wheels, the pair of rack bars 53 and 54 in the rack case 50 attached to the vehicle frame move the same distance in the same direction in the left-right direction.

  When the rear wheel steering device 20 is driven by the driving force of the normal steering actuator 31, the first rack bar 53 and the second rack bar 54 are moved in the same direction by the same distance in the left-right direction as shown in FIG. As shown, the left and right wheels w of the rear wheels are steered to a predetermined angle. At this time, the rear wheels and the front wheels are steered in opposite phases (in the figure, the front wheels are steered to the right and the rear wheels are steered to the left), allowing a small turning with a smaller turning radius than in the normal travel mode. It becomes. 4 shows a state in which the rear wheels and the front wheels are steered by the same angle in opposite phases, the steered angles may be different between the front and rear.

(In-situ rotation mode)
The in-situ rotation mode is shown in FIG. The synchronous gear box 66 is fixed to the rack case 50 by the fixing mechanism 67 at a position set when the vehicle travels straight, and the coupling mechanism 63 (see FIG. 9) is separated. By rotating the rotary shaft 61, the first rack bar 53 and the second rack bar 54 in the rack case 50 can be operated separately. At this time, both rack bars 53 and 54 are moved by the action of the first synchronization gear 55 provided between the first rack bar 53 and the second rack bar 54 by the input from the first rotating shaft 61 to the pinion gear 62. The left and right wheels w are steered in opposite directions while moving the same distance in opposite directions. Instead of operating the steering wheel 2 by the driver, the first rotating shaft 61 can be rotated by the driving force of the mode switching actuator 32.

  In this manner, by fixing the synchronous gear box 66 to the rack case 50 by the fixing mechanism 67, the pair of rack bars 53 and 54 can be connected to each other even if there is a difference in the inclination of the ground contact surface of the tire or the friction state. Using the fixed synchronous gear box 66 as a reference, it can move in the opposite direction by the same distance. For this reason, the left and right wheels w can be quickly set as target wheel angles, and the steering angle control can be stably performed.

  The first rack bar 53 and the second rack bar 54 are moved in opposite directions, and the coupling mechanism 63 is coupled and fixed at a position where the central axes of all the four front and rear wheels w are substantially directed to the vehicle center as shown in FIG. Let Since the central axes of all the four wheels w are substantially directed to the vehicle center, the vehicle center is in a certain state (or substantially not moved) by the driving force of the in-wheel motor M provided on each wheel w. ) Is maintained, and so-called in-situ rotation is possible. At this time, by keeping the synchronous gear box 66 fixed to the rack case 50, stable in-situ rotation is possible.

  In FIG. 5, each wheel w is equipped with an in-wheel motor M. However, if at least one wheel w is equipped with an in-wheel motor M and that one in-wheel motor M is activated, the in-situ rotation is performed. Is possible. Further, the fixing mechanism 67 may not be used.

(Lateral movement mode)
The lateral movement mode is shown in FIG. Similar to the in-situ rotation mode, the fixing gear 67 fixes the synchronous gear box 66 to the rack case 50 at the straight traveling position and separates the coupling mechanism 63 (see FIG. 9). Is operated to rotate the first rotation shaft 61, the first first rack bar 53 and the second rack bar 54 in the rack case 50 can be operated separately. At this time, due to the input of the pinion gear 62 from the mode switching actuator 32, the rack bars 53, 54 are mutually connected by the action of the first synchronization gear 55 provided between the first rack bar 53 and the second rack bar 54. The left and right wheels w are steered in the opposite direction by moving the same distance in opposite directions. Instead of operating the steering wheel 2 by the driver, the first rotating shaft 61 can be rotated by the driving force of the mode switching actuator 32. Thus, by fixing the synchronous gear box 66 to the rack case 50 by the fixing mechanism 67, the pair of rack bars 53 and 54 can be moved to the left and right even if there is a difference in the inclination of the ground contact surface of the tire or the friction state. Can move the same distance in the opposite direction. For this reason, the left and right wheels w can be quickly set as target wheel angles, and the steering angle control can be stably performed.

  The steering device is driven by the rotation input from the first rotating shaft 61 to the first pinion gear 62 so that all the four front and rear wheels w are directed in a direction of 90 degrees with respect to the straight traveling direction (left and right direction with respect to the straight traveling direction of the vehicle). The first rack bar 53 and the second rack bar 54 in 10, 20 are moved in opposite directions. And the coupling mechanism 63 (refer FIG. 9) is couple | bonded in the position where the wheel w became the said 90 degree | times, and the pair of rack bars 53 and 54 are fixed.

  At this time, unlike the in-situ rotation mode, the first rack bar 53 and the second rack in the rack case 50 of the steering devices 10 and 20 are released by releasing the state where the synchronous gear box 66 is fixed to the rack case 50. It is possible to finely adjust the direction (tire angle) of the wheel w by moving the bar 54 integrally in the left-right direction with respect to the straight traveling direction by the driving force of the normal steering actuator 31 or the operation of the steering 2. Become.

  FIG. 6 shows the positional relationship between the front and rear wheel steering devices 10 and 20 and the direction of the wheels w in the lateral movement mode. Compared to the in-situ rotation mode, the pair of rack bars 53 and 54 protrudes outward, and the connecting portion of the tie rods 12 and 22 to the wheels w is located on the outermost side in the vehicle width direction. Mode. Even in this lateral movement mode, the direction (tire angle) of the wheel w can be finely adjusted by the driving force of the normal steering actuator 31 or the operation of the steering 2.

(Other travel modes)
As another travel mode, for example, when the electronic control unit (ECU) 40 recognizes that the vehicle 1 is traveling at a high speed, the actuator driver 30 can change the rear wheel mode switching actuator based on the output of the ECU 40. 32, the left and right wheels w (RL, RR) of the rear wheels are set to a state (toe-in state) where the front side is slightly closed from the parallel state. Thereby, the stable high-speed driving | running is attained.

  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.

(Switching mode)
In addition, when switching each driving mode to the in-situ rotation mode or the lateral movement mode, it is preferable that the driving is performed by the driver's steering operation as described above, but the driver operates the mode switching means 42 in the passenger compartment. By doing so, it is possible to select the normal traveling mode, the spot rotation mode, the lateral movement mode, the small turn mode, and the like. If the selection can be switched by a switch operation or the like, a safer operation is possible.

  In the normal traveling mode, in the front wheel steering device 10, the ECU 40 calculates and outputs the required amount of movement of each rack bar 53, 54 in the left-right direction based on information from the sensor 41 accompanying the rotation operation of the steering 2. Based on the output, the front wheel normal steering actuator 31 is commanded to move the rack case 50 containing the rack bars 53 and 54 integrally in the left-right direction, and the left and right wheels w are rotated in the required direction by the required angle. Rudder.

  For example, if the mode switching means 42 is operated and the in-situ rotation mode is selected, the four wheels w can be steered through the front and rear wheel steering devices 10 and 20 so that the center of the vehicle 1 has the center of rotation. it can. This operation is permitted only when the vehicle 1 is stopped. At this time, the ECU 40 calculates and outputs the amount of relative movement of the two rack bars 53 and 54 in the left-right direction. Based on the output, the actuator driver 30 instructs the front / rear wheel mode switching actuator 32 to perform turning.

  If the mode switching means 42 is operated and the lateral movement mode is selected, the four wheels w are steered through the front and rear wheel steering devices 10 and 20 so that the steering angle of the four wheels w is 90 degrees. Can do. At this time, the ECU 40 calculates and outputs the amount of relative movement of the two rack bars 53 and 54 in the left-right direction. Based on the output, the actuator driver 30 instructs the front / rear wheel mode switching actuator 32 to perform turning. At this time, the normal steering actuator 31 may be set to a state where it does not operate as necessary, or the operation of the normal steering actuator 31 is permitted, so that the steering angle can be finely adjusted by the operation. Is possible.

  Furthermore, if the mode switching means 42 is operated and the small turning mode is selected, the front wheels and the rear wheels are steered in opposite phases and can be set so that the small turning is possible. At this time, in the rear-wheel steering device 20, the movement amount in the left-right direction of the rack case 50 that accommodates the pair of rack bars 53, 54 is similarly calculated and output by the ECU 40 based on the operation of the steering 2 and the like. . Based on the output, the actuator driver 30 commands the normal steering actuator 31 and the mode switching actuator 32 for the front and rear wheels to perform the steering. The control of the front wheel steering device 10 is the same as in the normal travel mode.

  As described above, in the front and rear wheel steering devices 10 and 20, based on the information from the sensor 41 that detects the steering angle or steering torque of the steering wheel 2 in the driver's seat and the input from the mode switching means 42, the ECU 40 A necessary amount of movement of the rack bars 53 and 54 in the left-right direction is output. Alternatively, the necessary amount of movement of the pair of rack bars 53 and 54 is output based on the determination of the traveling state by the ECU 40 itself. Based on the output, the actuator driver 30 can steer the front and rear wheels in a predetermined direction through the normal steering actuator 31 and the mode switching actuator 32.

  In this embodiment, the control of the steering device 20 for the rear wheels employs a steer-by-wire system in which a steering operation or mode switching operation performed by the driver is replaced with an electric signal for turning.

  The steering device 10 for the front wheels may be a steer-by-wire system using the normal steering actuator 31 and the mode switching actuator 32 as in the case of the rear wheels. In particular, the driver operates as the normal steering actuator 31. A motor or the like connected to the steering 2 or the steering shaft 3 may be provided, and the motor or the like may calculate and assist the torque required to move the rack bars 53 and 54 in the left and right directions by the rotation of the steering shaft 3. Good. At this time, the mode switching actuator 32 is the same as that of the rear wheel.

  Note that a general steering device using a mechanical rack and pinion gear mechanism or the like may be employed as a mechanism used for turning the front wheel steering device 10 in the normal travel mode.

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

  In the present invention, in the normal traveling mode, the pair of rack bars 53 and 54 are fixed and operated without any sense of incongruity with the conventional steering operation, and the pair of rack bars 53 and 54 are moved in a different direction, thereby making a small turn, Various special driving modes such as spot rotation and lateral movement can be realized. Further, by using the pair of rack bars 53 and 54 that can be switched between separation and fixation, the cost can be reduced without using complicated mechanisms and controls. That is, in the vehicle 1 that gives the steering angle to the four wheels, the front and rear wheels w can be steered to the steering angle of the same phase or the opposite phase without using a complicated mechanism to cope with a small turn or a lateral movement. .

  Moreover, not only the operation in the normal driving mode, but also when changing the wheel angle to the special driving mode (spot rotation, lateral movement), the wheel w is steered by the steering operation of the driver. A sense of security can be given. For example, when the driver senses an abnormal state such as the wheel w coming into contact with an obstacle such as a curb or the steering wheel 2 becoming heavy, the steering operation is stopped or the steering wheel 2 is returned according to the driver's judgment. Thus, since an abnormal state can be avoided quickly, an effect of increasing the driver's sense of security can be expected.

10, 20 Steering device 12, 22 Tie rod 31 Steering actuator 50 Rack case 53, 54 Rack bar 55 Synchronous gear 60 Rack bar operating means 62 First pinion gear 63 Connection mechanism 65 Second pinion gear 66 Synchronous gear box 67 Fixing mechanism w wheel

Claims (7)

Tie rods (12, 22) connected to the left and right wheels (w) and steering the left and right wheels (w);
A pair of rack bars (53, 54) respectively connected to the tie rods (12, 22) of the left and right wheels (w);
The pair of rack bars (53, 54) mesh with each other, and the movement of one rack bar (53) in one direction with respect to the parallel direction of the rack teeth is converted into the movement of the other rack bar (54) in the other direction. A synchronous gear (55) to
By the steering operation of the driver, the pair of rack bars (53, 54) is moved in the left-right opposite direction and the left-right same direction along the parallel direction of the rack teeth of the respective rack bars (53, 54). Rack bar operating means (60) capable of,
And the pair of rack bars (53, 54) is always meshed with the synchronous gear (55) . A synchronization gear box (66) holding at least one of the synchronization gears (55) and movable in the left-right direction;
A rack case (50) that holds the pair of rack bars (53, 54) and is fixed to the vehicle frame;
A fixing mechanism (67) capable of fixing the synchronous gear box (66) to the rack case (50);
The steering apparatus according to claim 1, further comprising: fixing the synchronous gear box (66) by the fixing mechanism (67) when the pair of rack bars (53, 54) is moved in the opposite direction. Tie rods (12, 22) connected to the left and right wheels (w) and steering the left and right wheels (w);
A pair of rack bars (53, 54) respectively connected to the tie rods (12, 22) of the left and right wheels (w);
The pair of rack bars (53, 54) mesh with each other, and the movement of one rack bar (53) in one direction with respect to the parallel direction of the rack teeth is converted into the movement of the other rack bar (54) in the other direction. A synchronous gear (55) to
A rack bar capable of moving the pair of rack bars (53, 54) in the opposite direction to the left and right along the parallel direction of the rack teeth of each rack bar (53, 54) by the steering operation of the driver. Operating means (60);
With
A synchronization gear box (66) holding at least one of the synchronization gears (55) and movable in the left-right direction;
A rack case (50) that holds the pair of rack bars (53, 54) and is fixed to the vehicle frame;
A fixing mechanism (67) capable of fixing the synchronous gear box (66) to the rack case (50);
When the pair of rack bars (53, 54) is moved in the left-right opposite direction, the synchronization gear box (66) is fixed by the fixing mechanism (67) , and the pair of rack bars (53, 54 ) is fixed . 54) A steering device in which 54) is always meshed with the synchronous gear (55) .   The steering apparatus according to claim 2 or 3, wherein the synchronous gear box (66) is fixed at a position of the synchronous gear box (66) when the vehicle is traveling straight.   Fixing by the fixing mechanism (67) opposes the synchronous gear box (66) and the pair of rack bars (53, 54) along the parallel direction of the rack teeth of the rack bar (53, 54), respectively. The steering device according to any one of claims 2 to 4, wherein the steering device is used when moving in a direction.   The operation means of the rack bars (53, 54) includes a first pinion gear (62) meshing with the one rack bar (53), and a second pinion gear (65) meshing with the other rack bar (54). The steering device according to any one of claims 1 to 5, further comprising a coupling mechanism (63) for coupling or separating the rotation shafts of the first and second pinion gears (62, 65). The steering apparatus (10) according to any one of claims 1 to 6, which is operated by a driver's steering operation and steers the front wheels,
A steering actuator (31) that operates in conjunction with the steering operation;
The steering device (20) according to any one of claims 1 to 6, wherein the rear wheel is steered in accordance with the operation of the steering actuator (31).
Steering device system with

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