WO2015050190A1

WO2015050190A1 - Steering device

Info

Publication number: WO2015050190A1
Application number: PCT/JP2014/076374
Authority: WO
Inventors: 裕也山口; 大場　浩量
Original assignee: Ntn株式会社
Priority date: 2013-10-03
Filing date: 2014-10-02
Publication date: 2015-04-09
Also published as: JP2015071363A

Abstract

In a steering device for a vehicle that provides a steering angle to four wheels, a connecting member (63) is separated or coupled via the meshing of a protruding portion (63c) of a movable portion (63a) and a recessed portion (63d) of a fixed portion (63b). When the connecting member (63) is separated, a pair of rack bars (53, 54) are moved in opposite directions by the action of a synchronization gear (55) in a special turning mode for lateral movement, for example. When the connecting member (63) is coupled, the pair of rack bars (53, 54) are moved in the same direction, enabling normal turning.

Description

Steering device

The present invention relates to a steering device that steers either a front wheel or a rear wheel, and more particularly to a steering device that includes 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.

Also, there is 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 (for example, see Patent Document 1 below).

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 below).

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

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

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. Accordingly, 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, the technique described in Patent Document 1 allows the vehicle to move in the lateral direction, turn around, 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 4 can perform toe adjustment, it cannot cope with a lateral movement or a small turn of the vehicle.

Thus, there is currently no simple mechanism that can achieve both smooth steering in normal driving and driving in a special mode such as lateral movement.

Therefore, an object of the present invention is to make it possible to cope with lateral movement, small turn, etc. without using a complicated mechanism in a vehicle that gives a steering angle to four wheels.

In order to solve the above problems, in the present invention, tie rods connected to the left and right wheels of the front wheels or rear wheels and steering the left and right wheels, and a pair of rack bars respectively connected to the tie rods of the left and right wheels, A synchronous gear that meshes with the pair of rack bars and converts the movement of the rack teeth of one rack bar in one direction relative to the parallel direction to the movement of the other rack bar in the other direction; A first pinion gear meshing with one of the rack bars, a first rotation shaft provided coaxially with the first pinion gear, a second pinion gear meshing with the other rack bar of the pair of rack bars, A second rotation shaft provided coaxially with the two-pinion gear, and a connection mechanism for connecting the first rotation shaft and the second rotation shaft so as to be separated or coaxially rotatable. The linking mechanism constitutes a steering device that meshes when the first rotating shaft and the second rotating shaft have a predetermined relative angle, and rotates the first rotating shaft and the second rotating shaft coaxially and integrally. did.

By connecting the wheels via a tie rod to a pair of rack bars that can be moved independently on the left and right, in a normal driving mode, the pair of rack bars can move in the same direction in the same distance, and the conventional steering Operate without any sense of incongruity with operation, and move the pair of rack bars in different directions to realize various driving modes such as small turn, spot turn, and lateral movement.

Also, by using a pair of rack bars that can be separated and fixed by a coupling mechanism, 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 addition, since the connecting mechanism integrates the first rotating shaft and the second rotating shaft by meshing at a predetermined relative angle, no relative slip occurs between the rotating shafts. For this reason, the pair of rack bars can move the same distance in the same direction, and the wheels can be accurately steered to a predetermined turning angle.

In the above configuration, the coupling mechanism includes a fixed portion provided on one side of the first rotating shaft and the second rotating shaft, and a moving portion provided on the other side, and the moving portion includes You may make it perform the said isolation | separation or connection by moving relatively to the axial direction of both rotating shafts with respect to the said fixing | fixed part.

In the configuration including the fixed portion and the moving portion, a convex portion is formed on one side of the fixed portion and the moving portion, and a concave portion is formed on the other side, and the convex portion and the concave portion mesh with each other to make the connection. You may do it.

In the configuration in which the convex portion and the concave portion are formed, a chamfered portion may be formed on at least one of the convex portion and the concave portion. Furthermore, it is good also as a structure which forms the said convex part and the said recessed part 2 or more each.

In the configuration in which the convex portion and the concave portion are formed, there are a plurality of the relative angles with which the coupling mechanism meshes, and the number of the concave portions formed in the fixed portion or the moving portion is formed in the fixed portion or the moving portion. It is good also as a structure smaller than the product of the number of the said convex parts and the number of the said relative angles. Furthermore, it is good also as a structure which provided the detection part with a larger outer diameter than the said convex part and the said recessed part in the outer periphery of the said moving part.

By connecting the wheels via a tie rod to a pair of rack bars that can be moved independently on the left and right, in a normal driving mode, the pair of rack bars can move in the same direction in the same distance, and the conventional steering Operate without any sense of incongruity with operation, and move the pair of rack bars in different directions to realize various driving modes such as small turn, spot turn, and lateral movement. In addition, by using a pair of rack bars that can be separated and fixed by a coupling mechanism, it is possible to reduce costs 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.

Image of vehicle using steering device of this embodiment The top view which shows 1st embodiment of this invention The top view which shows normal driving mode (normal steering mode) in the vehicle of FIG. FIG. 2 is a plan view showing the small turn mode in the vehicle of FIG. The top view which shows the spot turning mode in the vehicle of FIG. FIG. 2 is a plan view showing a lateral movement (parallel movement) mode in the vehicle of FIG. The perspective view which shows the external appearance of a steering device Plan view showing the inside of the steering device Side view showing details of rack bar operating means of steering device Plan view showing the inside of the steering device (normal driving mode) Plan view showing the inside of the steering device (lateral movement mode) The top view of a connection mechanism is shown, (a) is a combined state, (b) is a separated state. The details of the coupling mechanism are shown, (a) is a plan view of the moving unit, (b) is a side view of the moving unit, (c) is a plan view of the fixed unit, and (d) to (f) are projections and recesses Diagram showing meshing position

Embodiments of the present invention will be described with reference to the drawings. In this embodiment, the in-wheel motor M is mounted in the wheels of all the front, rear, left, and right wheels w in the steering device for the drive 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 wheel w through the steering rod 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 the drive system of the vehicle 1 of the first embodiment. In this embodiment, the

steering devices

10 and 20 of the present invention 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.

The steering device 10 for the front wheels is normally steered by operating the steering 2, and the steering device 20 for the rear wheels is a four-wheel steering mechanism that enables steering according to the travel mode by an actuator such as a motor. I have.

However, a vehicle equipped with the steering device of the present invention only on the front wheel or the rear wheel can also be adopted, or the steering device of the present invention is equipped only on the rear wheel, and the front wheel is a normal general vehicle. A vehicle equipped with a simple steering device can also be used.

The front and

rear steering devices

10 and 20 are each 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.

The connecting

members

11 and 21 of the rack bars 53 and 54 are hingedly 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.

As shown in FIG. 7, the first rack bar 53 and the second rack bar 54 are each a rack case (steering cylinder) 50 that extends 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 support of the rack case 50 to the vehicle 1 can be directly or indirectly screwed to the frame of the vehicle 1 via a flange portion 50a provided in the rack case 50, for example.

The first rack bar 53 and the second rack bar 54 can move within the rack case 50 in the same direction in the same direction in the left-right direction with respect to the straight traveling direction of the vehicle. As shown in FIG. 2, 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.

As shown in FIG. 8, between the first rack bar 53 and the second rack bar 54, rack grooves that are formed on both rack bars 53, 54 and face each other, that is, a synchronization rack of the first rack bar 53. A first synchronization gear 55 that meshes with the groove 53 a and the synchronization rack groove 54 a of the second rack bar 54 is provided. 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.

Between the

adjacent gears

55a and 55b of the first synchronization gear 55 and between the

gears

55b and 55c, gears 56a and 56b constituting the second synchronization gear 56 are arranged, respectively. The second synchronization gear 56 meshes only with the first synchronization gear 55 without meshing with the synchronization rack groove 53 a of the first rack bar 53 or the synchronization rack groove 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.

Steering devices

10 and 20 are each provided with a rack bar operation means 60 as shown in FIG. 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.

The pinion shaft 61 is connected to the steering shaft 3 (in the case of a general vehicle (see FIG. 2)) or an actuator 31 such as a motor that is operated by the rotation operation of the steering 2 (see FIG. 2). The pinion shaft 61 includes a first pinion gear 62 that is integrally or integrally rotatable. The first pinion gear 62 is disposed on the first rack bar 53, and the second pinion gear 65 is disposed on the second rack bar 54. Each is engaged. The two

rack bars

53 and 54 extend in parallel to each other.

The rack bar operation means 60 includes a connecting mechanism 63 that allows the first pinion gear 62 and the second pinion gear 65 to be coupled and separated in the rotational direction. This figure shows a state in which the coupling mechanism 63 is separated. As described above, when the first rack bar 53 is moved in one direction with respect to the parallel direction of the rack teeth by the driving force input from the rack bar operating means 60 while the coupling mechanism 63 is in the separated state, the movement is performed. Is converted into the movement of the second rack bar 54 in the other direction by the first synchronization gear 55.

The first rack bar 53 and the second rack bar 54 are provided with 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.

When the first rack bar 53 moves from the state shown in FIG. 10 (straight forward state) to the state shown in FIG. 11 (lateral movement mode state) by the input of the driving force from the rack bar operating means 60, the first The force is transmitted to the second rack bar 54 via the first synchronization gear 55, and the second rack bar 54 moves from the state shown in FIG. 10 to the state shown in FIG.

In this straight traveling state (see FIG. 10), the relative rotation of the first pinion gear 62 and the second pinion gear 65 is 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 wheel 2, the first rack bar 53 and the second rack bar 54 move left and right in the same direction in the rack case 50 attached to the chassis in the same direction.

Further, in the state of the lateral movement mode (see FIG. 11), 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. Yes. By the meshing of the synchronization gear 55, the rack bars 53 and 54 move the same distance in the opposite direction with respect to the synchronization gear box 66. 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. And the connection mechanism 63 is couple | bonded in the position where the turning angle of the wheel became 90 degree | times.

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

The rack bar operation means 60 of the front wheel steering device 10 is operated by the driving force of the mode switching actuator 32 that operates in conjunction with the rotation operation of the steering 2 performed by the driver, or the operation of the mode switching means 42 provided in the vehicle 1. The first rotation shaft (pinion shaft) 61 and the first pinion gear 62 attached to the first rotation shaft 61 so as to be integrally rotatable by the driving force of the mode switching actuator 32 operating in conjunction with the first rotation shaft 61 (see FIG. 2). (See FIG. 9). The 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.

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).

FIG. 7 is an overall view of the

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.

Furthermore, a connecting 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 second rotating shaft 64 and a moving portion 63 a on the first rotating shaft 61 side. The moving part 63a is pressed against the fixed part 63b by an elastic member such as a spring (not shown), and as shown in FIG. By connecting the part 63c, both the

rotating shafts

61 and 63 can be rotated together. 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 and convex portions being reversed. The number of the convex parts 63c and the concave parts 63d is not particularly limited, but it is preferable to form at least two parts in order to ensure the coupling by the connecting mechanism.

Further, by forming the chamfered portion 68 on at least one of the convex portion 63c and the concave portion 63d, when the coupling mechanism 63 is coupled, the concave portion 63d and the convex portion 63c are hardly caught, and the change of the steering mode can be smoothly performed. It can be performed. The moving part 63a is provided with a detecting part 67 having an outer diameter larger than the outer diameters of the convex part 63c of the moving part 63a and the concave part 63d of the fixed part 63b. By providing the detection unit 67 in this manner, it can be easily confirmed from the outside whether the coupling mechanism 63 is in the separation position or the coupling position.

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. 12B shows the separated state.

As shown in FIG. 9, the first pinion gear 62 meshes with the first rack bar 53, and the second pinion gear 65 meshes with the second rack 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 (see FIG. 8). 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, the pair of rack bars 53 and 54 is separately opposite to the state in which the pair of rack bars 53 and 54 move in the same direction and the same distance in the left and right direction. Switching to a state of moving in the direction can be easily performed.

When the coupling mechanism 63 is in a coupled state, that is, in a state in which 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, the steering 2 performed by the driver is performed. By moving the first rack bar 53 and the second rack bar 54 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 conjunction with the rotation operation. The left and right wheels w can be steered in the same direction around the kingpin axis. At this time, the first rack bar 53 and the second rack bar 54 move the same distance in the same direction, so that the first synchronization gear 55 does not rotate.

When the coupling mechanism 63 is in a separated state, that is, the first pinion gear 62 and the second pinion gear 65 are separated, and the first rack bar 53 and the second rack bar 54 do not move together, The steering 2 is rotated. In conjunction with this rotation operation, the normal steering actuator 31 is driven. With this driving force, the first rack bar 53 and the second rack bar 54 can be moved in opposite directions to the left and right with respect to the straight traveling direction of the vehicle by the action of the intervening synchronous gear 55. As a result, the left and right wheels can be steered in opposite directions around the kingpin axis, that is, in directions opposite to each other.

That is, in this embodiment, rotation due to operation of the steering wheel 2 during normal operation is input to the first rotation shaft 61 through rotation of the steering shaft 3. The rack bar operating means 60 also functions as means for moving the first rack bar 53 and the second rack bar 54 in the same direction and the same distance during normal operation.

Also, at the time of mode switching, the driving force of the mode switching actuator 32 is input to the rack bars 53 and 54 through the rotation of the pinion gears 62 and 65, respectively. When the driving force of the mode switching actuator 32 is input to the rack bars 53 and 54 through the rotation of the pinion gear 62, the rotation of the steering shaft 3 may not be transmitted to the steering 2. The transmission may be allowed.

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.

Also, the mode switching actuator 32 can play its role by the driving force of the in-wheel motor M arranged on the left and right of the steering. Further, the normal steering actuator 31, the mode switching actuator 32, or the left and right in-wheel motors M can also assist each other.

The operation of the coupling mechanism 63 will be described with reference to FIG. When the upper end of the figure is defined as 0 degrees and the angle is defined in the clockwise direction, the moving part 63a of the coupling mechanism 63 has convex portions that stand up toward the fixing part 63b at three positions of 0 degrees, 135 degrees, and 225 degrees. 63c is formed, and the fixing portion 63b is formed with concave portions 63d that mesh with the convex portions 63c at seven positions of 0 degree, 45 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees. Yes. Thus, when the convex part 63c and the recessed part 63d are formed, this moving part 63a and the fixing | fixed part 63b can mesh | engage only in five relative angles. That is, one of the convex portions 63c ₁ of the three positions of the convex portions _63c 1 ~ 63c ₃ are five recesses _63d 1 of the seven positions of the concave portions _{_{_{63d 1 ~ 63d 7, 63d 2}}} ,

63d

3 , 63d ₄ , 63d ₆ , the moving part 63a and the fixed part 63b can mesh with each other.

In the configuration shown in FIG. 13, it is possible to set a maximum of five steering modes in which the moving portion 63a and the fixed portion 63b are engaged. For example, the engagement in FIG. ) Can be set to the in-situ rotation mode, and the engagement shown in FIG. 5F can be set to the lateral movement mode (the black portions in each figure indicate the meshed portions of the convex portion 63c and the concave portion 63d in each mode). ).

If the moving portion 63a and the fixed portion 63b can mesh with each other only at a predetermined relative angle in this way, it is possible to prevent erroneous engagement in the steering mode in which both should not be meshed. The operational reliability at the time of mode switching can be greatly improved.

In addition, the number of concave portions 63d (seven locations) formed in the fixed portion 63b is equal to the number of convex portions 63c formed in the movable portion 63a (three locations) and the relative angle at which the movable portion 63a and the fixed portion 63b can mesh. Is less than 15, which is the product of the number of (5). This means that there is a recess 63d that shares meshing when the steering mode is switched. For example, when the steering mode is switched from the normal travel mode (FIG. (D)) to the lateral movement mode (FIG. (F)), the meshing is shared in the two

recesses

63d ₁ and 63d ₃ . The In this way, by sharing the concave portions 63d involved in the meshing, the number of the concave portions 63d formed in the fixed portion 63b (or the moving portion 63a) can be reduced as much as possible. By reducing the number of the concave portions 63d, it is possible to prevent the strength of the fixing portion 63b from being lowered due to the formation of the concave portions 63d as much as possible, and to further improve the reliability of the driving force transmission by the coupling mechanism 63.

Hereinafter, a description will be given of several driving modes when the steering device having each of these configurations is mounted on the vehicle 1.

(Normal driving mode)
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 in the same direction by the same distance at the wheel position in the straight traveling state shown in FIG. The first pinion gear 62 and the second pinion gear 65 shown are connected to a connecting mechanism 63 that can be connected to or separated from each other (see FIGS. 12A and 13D). Then, the first rack bar 53 and the second rack bar 54 of the steering device 10 move in the rack case 50 attached to the frame of the vehicle 1 by the same distance in the left-right direction in the same direction.

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, when the two

rack bars

53 and 54 are completely fixed together, traveling equivalent to that of a normal vehicle becomes possible. 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. 9 is connected (see FIG. 12A). As with the front wheels, the first rack bar 53 and the second rack bar 54 in the rack case 50 attached to the vehicle frame move in the same direction in the same direction in the left-right direction.

When the rear-wheel steering device 20 is moved in the left-right direction with respect to the straight traveling direction by the driving force of the normal steering actuator 31, the first rack bar 53 and the second rack bar 54 are also moved in the same direction by the same distance. As shown in FIG. 4, 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.

(Spot turn mode)
The spot turn mode is shown in FIG. By separating the coupling mechanism 63 (see FIG. 9) (see FIG. 12B), the 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. In opposite directions, the left and right wheels w are steered in the opposite direction by the same angle, moving to the left and right by the same distance with respect to the gear box that houses the synchronous gears 55 and 56.

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. (See FIGS. 12A and 13E). 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. ), So-called in-situ turning 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, in-situ turning is performed. Is possible.

(Lateral movement mode)
The lateral movement mode is shown in FIG. Similarly to the in-situ turning mode, by separating the coupling mechanism 63 (see FIG. 9), 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.

By inputting rotation from the mode switching actuator 32 to the first pinion gear 62 so that all 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 steering device 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, the first rack bar 53 and the second rack bar 54 in the rack case 50 of the

steering devices

10 and 20 are 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. It is possible to finely adjust the direction (tire angle) of the wheel w by moving the same distance in the same direction.

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 turning mode, the pair of rack bars 53 and 54 protrude outward, and the connecting portion of the

tie rods

12 and 22 to the wheel 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 wheels 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)
Note that the mode switching means 42 is used as appropriate when switching between the above-described travel modes. By operating the mode switching means 42 in the passenger compartment, it is possible to select the normal traveling mode, the spot turn mode, the lateral movement mode, the small turn mode, and the like. If switching can be performed by a switch operation or the like, 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 wheel 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, 54 in the same direction in the left-right direction, and the left and right wheels w are required in the required direction. Steer only the angle.

For example, if the mode switching means 42 is operated and the spot turn 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 a 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 adopts a steer-by-wire system in which the steering operation performed by the driver and the mode switching operation are replaced with electric signals 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.

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

The various steering modes described above are examples, and various other controls using these mechanisms are possible.

In the present invention, in the steering device, the coupling mechanism 63 that allows the pair of rack bars 53 and 54 that steer the left and right wheels w to be separated or combined is adopted. In the normal traveling mode, the connecting mechanism 63 is in the coupled state, and the left and right wheels w can be steered in the same direction without a sense of incongruity as in the conventional steering operation. On the other hand, in special turning modes such as spot turning and lateral movement, the connecting mechanism 63 can be in a separated state and the left and right wheels w can be turned in the opposite direction. By adopting the coupling mechanism 63, it is possible to move in the lateral direction, turn around, etc. at low cost without using a complicated mechanism.

12, 22 Tie rod 53 (First) rack bar 54 (second) rack bar 55 Synchronous gear 61 First rotation shaft (pinion shaft)
62 first pinion gear 63 coupling mechanism 63a moving part 63b fixed part 63c convex part 63d concave part 64 second rotating shaft 65 second pinion gear 67 detecting part 68 chamfered part w wheel

Claims

Tie rods (12, 22) connected to the left and right wheels (w) of the front wheels or rear wheels 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 first pinion gear (62) meshing with one rack bar (53) of the pair of rack bars (53, 54), and a first rotating shaft (61) provided coaxially with the first pinion gear (62). ), A second pinion gear (65) meshing with the other rack bar (54) of the pair of rack bars (53, 54), and a second rotating shaft provided coaxially with the second pinion gear (65). (64), and a connecting mechanism (63) for connecting the first rotating shaft (61) and the second rotating shaft (64) so as to be separated or coaxially rotatable.
The coupling mechanism (63) meshes with the first rotating shaft (61) when the first rotating shaft (61) and the second rotating shaft (64) are at a predetermined relative angle. And a steering device for rotating the second rotary shaft (64) coaxially and integrally.
The connection mechanism (63) includes a fixed part (63b) provided on one side and a moving part (63b) provided on the other side of the first rotary shaft (61) and the second rotary shaft (64). 63a), and the separation or connection is performed by moving the moving part (63a) relative to the fixed part (63b) in the axial direction of both rotating shafts (61, 64). Steering device.
Of the fixed part (63b) and the moving part (63a), a convex part (63c) is formed on one side and a concave part (63d) is formed on the other side, and the convex part (63c) and the concave part (63d) are engaged with each other. The steering apparatus according to claim 2, wherein the connection is made.
The steering device according to claim 3, wherein a chamfered portion (68) is formed in at least one of the convex portion (63c) and the concave portion (63d).
The steering device according to claim 3 or 4, wherein each of the convex portion (63c) and the concave portion (63d) is formed at two or more locations.
There are a plurality of the relative angles with which the coupling mechanism (63) meshes, and the number of the recessed portions (63d) formed in the fixed portion (63b) or the moving portion (63a) is equal to the fixed portion (63b) or the The steering device according to any one of claims 3 to 5, wherein the steering device is smaller than a product of the number of the convex portions (63c) formed on the moving portion (63a) and the number of the relative angles.
The steering according to any one of claims 3 to 6, wherein a detection part (67) having an outer diameter larger than that of the convex part (63c) and the concave part (63d) is provided on an outer periphery of the moving part (63a). apparatus.