JP2861639B2 - Vehicle rear wheel steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel steering device for a vehicle, and more particularly to a rear wheel steering device for a four-wheel steering vehicle.

[0002]

2. Description of the Related Art A four-wheel steering vehicle is equipped with a front wheel steering device and a rear wheel steering device. The front wheel and the rear wheel are steered in an interlocked manner to improve turning stability at high speed running and low speed running. The aim is to reduce the turning radius at the time. Conventionally, as a rear wheel steering device, an input shaft extending from the front wheel steering device and rotating in conjunction with the steering of the front wheel, a steering shaft capable of steering the rear wheel by displacing in the vehicle width direction, and a rotation of the input shaft. Some include a cam mechanism that converts the displacement of the steering shaft in the axial direction, a centering mechanism that is provided in the middle of the steering shaft, positions the steering shaft at the neutral position, and maintains the straight running state of the rear wheels.

When a driver performs a steering operation, an input shaft rotates, and accordingly, a cam mechanism displaces a steering shaft in an axial direction. That is, when the input shaft is rotated, the cam mechanism first displaces the steering shaft to one side to steer the rear wheels to the same phase side, and then returns the steering shaft to the neutral position to make the rear wheels go straight, Further, the steering shaft is displaced to the other side to steer the rear wheels to the opposite phase.

[0004] With this arrangement, when the vehicle is changing lanes during high-speed running, in which the steering angle of the front wheels is relatively small, the rear wheels are steered to the same phase, thereby improving the turning stability of the vehicle. On the other hand, at the time of a garage entry operation in which the front wheels are largely steered,
The rear wheels are steered to the opposite phase, and the turning radius of the vehicle decreases. Also, when the vehicle is running straight, the spring of the centering mechanism positions the steering shaft at its neutral position to ensure the straight running stability.

[0005]

In this type of rear-wheel steering device, when the rear wheels are steered to the opposite phase, the vehicle always goes through a straight traveling state. That is, although the front wheels are steered, the rear wheels may go straight, and the steering angle of the front wheels and the displacement of the steering shaft do not always correspond one-to-one.

However, the centering mechanism attached to the steering shaft exerts the elastic force of the spring to keep the steering shaft in its neutral position regardless of whether the front wheels are being steered. There is a problem that the centering mechanism operates at an appropriate time. The present invention has been made to solve the above-described problem, and has as its object to provide a rear wheel steering device for a vehicle in which a centering mechanism is prevented from malfunctioning.

[0007]

According to the present invention, there is provided an input shaft extending from a front wheel steering device of a vehicle and rotating in conjunction with steering of a front wheel, and extending in a vehicle width direction.
A rear-wheel steering device comprising: a steering shaft that moves in a vehicle width direction to steer a rear wheel; and a unit that converts rotation of an input shaft into axial displacement of the steering shaft. This centering mechanism is located outside the input shaft.
Side, fixed to the vehicle body and input shaft
A housing for rotatably supporting a, is disposed on the outer periphery of the hand <br/> input shaft in the housing, viewed in the direction of rotation of one end an input shaft
And the other end has a biasing force in the other direction.
And a centering spring, base end phase on the outer periphery of the input shaft <br/> pair rotatably supported to extend in a radial direction of the input shaft, a first arm for engaging one end of the centering spring, the input shaft proximal to the outer periphery is supported relatively rotatably extends in the radial direction of the input shaft, a second arm for engaging the other end of the centering spring, disposed in the housing, the centering scan
A first stopper for limiting rotation in one direction of the first arm against the urging force of the pulling, provided in the housing, Se
A second stopper for limiting rotation in the other direction of the second arm against the urging force of the pointer ring spring is fixed to the input shaft, cell when the input shaft is rotated in the other direction from the neutral position < a first pressing member that presses the first arm in the other direction against the elastic force of the centering spring, and a first pressing member that is fixed to the input shaft, and that moves when the input shaft is rotated in one direction from the neutral position. a second pressing member for pressing the second arm in one direction against the elastic force of the spring.

[0008]

In a state where the steering operation is not performed, the centering spring presses the first and second arms against the first and second stoppers by the urging force , so that the first and second arms press the first and second pressing members. The input shaft is positioned at the neutral position while holding the member at a predetermined position.

The steering is operated, and the input shaft is in the neutral position.
When the second arm rotates in one direction, the second pressing member rotates the second arm in one direction. At this time, since the first stopper restricts rotation of the first arm in one direction, the centering spring is elastically deformed. Therefore, the elastic force acts in a direction of pressing the second arm against the second stopper, that is, a direction of returning the input shaft to the neutral position.

When the input shaft rotates in the other direction from the neutral position , the first pressing member rotates the first arm in the other direction. At this time, since the second stopper restricts the rotation of the second arm in the other direction, the centering spring is elastically deformed. Therefore, this elastic force acts in the direction of pressing the first arm against the first stopper, that is, in the direction of returning the input shaft to the neutral position.

The input shaft extends from the front wheel steering device, and the rotation angle of the input shaft from the neutral position corresponds to the front wheel steering angle. Therefore, when the vehicle is in the straight traveling state, the centering mechanism is operated to bring the rear wheels into the straight traveling state.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of a rear wheel steering device to which the present invention is applied. A rear wheel steering device 10 includes an input shaft 11 extending from a front wheel steering device 1, a steering shaft 12 extending in a vehicle width direction, and an input shaft. It comprises an inscribed cam mechanism 13 for converting the rotation of the shaft 11 into a displacement of the steering shaft 12 in the axial direction, a centering mechanism 14 for positioning the input shaft 11 at its neutral position, and the like.

The front wheel steering device 1 for steering the front wheels 2 includes, for example, a rack and pinion type steering gear mechanism.
When the steering wheel 4 in the driver's seat is operated, the pinion gear 5 displaces the rack 6 in the vehicle width direction.
Each tie rod 7 is connected to each front wheel 2 via each knuckle arm 8.
At the same time. The input shaft 11 extending rearward from the front wheel steering device 1 rotates in conjunction with the steering of the front wheels 2. That is, the pinion gear 21 is provided at the front end of the input shaft 11, and the pinion gear 21 is rotated by the displacement of the rack 6. Therefore, input shaft 1
The rotation angle of 1 corresponds to the amount of displacement of the rack 6, that is, the steering angle of the front wheels 2.

The input shaft 11 extends to the rear of the vehicle, and its rear end is disposed in a housing 26 described later, and is rotatably supported by bearings 22 (FIG. 7). At a position near the rear end of the input shaft 11, a drive gear 24 is provided so as not to rotate relatively. As shown in FIG. 2, the housing 26 includes a housing main body 27, a lid-shaped rear cover 28 screwed to the housing main body 27, and the like. It is screwed and fixed to a rear cross member (not shown) so as not to fall off. The interior of the housing 26 includes first to third spaces 30 to 32. The first space 30 is located at the center,
To accommodate. The second space 31 extends right and left from a position on the front side of the first space 30. The third space 32 is the first space 30
Extends forward from the lower right side of FIG.

The internal cam mechanism 13 includes a rotor 35, an internal cam 36, a pair of rollers 37, and the like, and is disposed in the first space 30 as described above. The rotor 35 is
It has a substantially triangular plate shape, and a flange 35a extending forward of the vehicle is formed on the front side surface, and a hub 35b is formed integrally on the rear side surface. The rotor 35 is supported by a rotor shaft 39 extending in the vehicle longitudinal direction. The rotor shaft 39 is press-fitted into the hole 35c of the rotor 35, so that they rotate together. The front end of the rotor shaft 39 is provided with a needle bearing 41.
, And the rear end is rotatably supported by the rear cover 28 via a ball bearing 42. The rear end of the rotor shaft 39 is fastened to the ball bearing 42 with a bolt 43 to prevent displacement of the rotor shaft 39 in the axial direction.

A driven gear 45 and an internal cam 36 are attached to the rotor 35. These rotors 35,
The driven gear 45 and the inscribed cam 36 are positioned with high accuracy by pins 46, and are screwed and fixed by a plurality of bolts 47. The driven gear 45 superimposed on the rear side surface of the roller 37 has a ring shape, is fitted into the hub 35b, and is arranged concentrically with the rotor shaft 39. The gear 45a provided on the outer periphery of the driven gear 45 meshes with the drive gear 24. Therefore, when the drive gear 24 rotates, the driven gear 45 and the rotor 35 rotate at a rotation speed reduced at a predetermined ratio. .

The inscribed cam 36 has a substantially triangular ring shape, is fitted on the inner surface of the flange 35a, and overlaps the front surface of the rotor 35. The inner circumference of the inscribed cam 36
The cam surface 36a is bilaterally symmetric. This cam surface 36
As shown in FIG. 4, the outline of “a” includes a non-working portion 51, first and second convex portions 52 and 53, and first and second concave portions 54 and 55.

More specifically, each inoperative portion 51 comes into contact with a pair of rollers 37 described later in the state of the inner cam 36 (the state shown in FIG. 4A) in the straight traveling state of the vehicle, and
This coincides with the virtual reference circle D indicated by the one-dot chain line in the figure. Each first convex portion 52 is located above each inoperative portion 51 in the drawing, and protrudes into the virtual reference circle D. The first recess 54 is provided with each first
It is located above the convex portion 52 in the drawing, and is recessed outside the virtual reference circle D. Further, each second concave portion 55 is located below each inoperative portion 51 in the figure, and is concave outside the virtual reference circle D. The second convex portion 53 is located below each second concave portion 55 in the drawing, and protrudes into the virtual reference circle D. The inactive portion 51, the first and second convex portions 52 and 53, and the first and second concave portions 54 and 55 are smoothly and continuously formed, and form a contour of the cam surface 36a. The cam surface 36a is formed so that the inscribed cam 36
Finished separately before being assembled into 5.

Each roller 37 is a cam follower that rolls along the cam surface 36a, and is attached to the steering shaft 12 via each roller shaft 57. The steering shaft 12 extends through the area above the rotor shaft 39 and in front of the inscribed cam 36 in the vehicle width direction, passes through the second space 31, and extends outside the housing 26. This steering shaft 1
2 are supported by the housing 26 via bearings (not shown) at both sides of the first space 30, and are displaceable relative to the housing 26 in the vehicle width direction.

At two predetermined positions of the steering shaft 12, shaft insertion holes 12a extending in the vehicle front-rear direction are formed. The shaft insertion holes 12a are arranged at a predetermined distance from each other, and face a region near the inside of the cam surface 36a. A roller shaft 57 is inserted into each of the shaft insertion holes 12a from the rear of the vehicle.

Each roller shaft 57 is composed of a large diameter portion 57a and a small diameter portion 57b, which are integrally formed. The small diameter portion 57b is inserted into the shaft insertion hole 12a, and is fixed by a nut 58. In addition, the large diameter portion 57
a is located in the region near the inner side of the inscribed cam 36, and therefore, the roller 37 that supports the relative rotation is rotatably supported on the cam surface 36.
a. In other words, each roller shaft 57 supports the pair of rollers 37 while abutting the pair of rollers 37 on the opposite sides of the cam surface 36a. Even when the internal cam 36 is rotated, each roller 37 is moved from the cam surface 36a. Roll without separating. Accordingly, each roller 37 is displaced in the vehicle width direction along the shape of the contour of the rotating cam surface 36a.

The small diameter portion 57b of the roller shaft 57
And the large diameter portion 57a are eccentric by a small distance (for example, about 1 mm) from each other. Therefore, when assembling the roller shaft 57 to the steering shaft 12, by rotating the roller shaft 57 with respect to the steering shaft 12, the distance between the cam surface 36a and the roller 37 can be changed, and the manufacturing error of each member can be changed. The gap between the cam surface 36a and the roller 37 generated due to the above-described factors can be absorbed.

On the other hand, the steering shaft 12 includes a shaft rotation preventing mechanism 6.
1 is provided (FIGS. 5 and 6). This shaft rotation prevention mechanism 61 is provided outside each roller 37, respectively.
They are configured symmetrically to each other. Therefore, only one shaft rotation preventing mechanism 61 will be described, and description of the other shaft rotation preventing mechanism 61 will be omitted. Shaft rotation prevention mechanism 6
5 includes a vertical surface 12c formed on the steering shaft 12, a stopper 63 that comes into contact with the vertical surface 12c, and the like, as shown in FIGS. The vertical surface 12c is formed on the front side of the steering shaft 12, and extends in the axial direction within a range where the steering shaft 12 can be displaced. The stopper 63 includes a stopper plate 65, an adjust plug 66, and the like.
The stopper plate 65 is fixed to the distal end surface of the adjust plug 66 and extends vertically. The adjust plug 66 is attached to a predetermined position of the housing 26 and abuts the stopper plate 65 so as to overlap the vertical surface 12c. This adjust plug 66 is fixed with a lock nut 67.

Here, the steering shaft 12 is connected to the rotor shaft 3.
9, the rollers 37 attached to the steering shaft 12 come into contact with the cam surface 36a at a position above the rotor shaft 39. Therefore, as a component force of the force acting on each roller 37 from the cam surface 36a,
A force for pushing down each roller 37 is generated. Each roller 37
The force that pushes down causes the roller shaft 57 to tilt and the steering shaft 12 to rotate about its axis. The stopper plate 65 of the shaft rotation preventing mechanism 61 abuts on the vertical surface 12c so as to overlap with the vertical surface 12c, and prevents the vertical surface 12c from being inclined. Therefore, the shaft rotation prevention mechanism 61 can prevent the rotation of the steering shaft 12.

On the other hand, a force acts radially outward from each roller 37 on the inscribed cam 36. A rotor shaft 39 supporting the rotor 35 has a bearing 41 at each end.
It is supported at 42. Therefore, the mounting rigidity of the internal cam 36 can be increased, and the force can be countered. Both ends of the steering shaft 12 are connected to tie rods 72 via ball joints 71, respectively. Therefore, when the steering shaft 12 is displaced in the vehicle width direction, the direction of each rear wheel 74 changes according to the displacement distance.

The centering mechanism 14 includes a centering spring 76 and a pair of sleeves 7 as shown in FIG.
8, 79, a pair of eccentric plates 81, 82, a pair of adjust bolts 84, 85, and the like, which are arranged in the third space 32. A pair of eccentric plates 8
1, 82 are arranged at a predetermined interval, and the input shaft 11
It is fitted around it so that it cannot rotate relatively. Each of the eccentric plates 81 and 82 has a disk shape, and is eccentric in directions opposite to each other as shown in FIGS. Pressing pieces 87, 88 are attached to the eccentric plates 81, 82, respectively. Each pressing piece 87, 88 is provided with an eccentric plate 81, 8
2 is disposed at a position where the radial dimension is maximized, and the pressing portions 87a and 88a protrude from the mutually facing surfaces of the eccentric plate (FIG. 7). Elastic members 90 are fixed to one side surface of the pressing portion 87a on the first eccentric plate 81 side and the other side surface of the pressing portion 88a on the second eccentric plate 82 side.

The pair of sleeves 78, 79 are arranged between the eccentric plates 81, 82 while being in contact with them, and are fitted to the input shaft 11 via bearings 92, 92. Therefore, the sleeves 78 and 79 are rotatable relative to the input shaft 11 and the eccentric plates 81 and 82.
A spacer 93 is provided between the sleeves 78 and 79 to prevent displacement in the axial direction.

Each of the sleeves 78, 79 has an arm 78a,
79a. Each arm 78a, 79a extends in the radial direction, and the arm 78a of the first sleeve 78
Opposing one side surface of the pressing portion 87 a on the first eccentric plate 81 side, the arm 79 a of the second sleeve 79 is
The pressing portion 88a on the eccentric plate 82 side is arranged to face the other side surface.

Therefore, when the input shaft 11 rotates in the direction of arrow C, the arm 78a of the first sleeve 78
While being pressed by the pressing portion 87a on the eccentric plate 81 side and rotating in the same direction, the pressing portion 88a on the second eccentric plate 82 side
Is separated from the arm 79a of the second sleeve 79. Conversely, when the input shaft 11 rotates in the direction of arrow CC, the arm 79a of the second sleeve 79
While being pressed by the pressing portion 88a on the second side and rotating in the same direction,
The pressing portion 87a on the first eccentric plate 81 side is separated from the arm 78a of the first sleeve 78. An anchor pin 95 is provided upright on each of the arms 78a, 79a of each of the sleeves 78, 79. Each anchor pin 95 extends in a direction facing each other.

Each of the adjusting bolts 84 and 85 is attached to the housing 26. 1st adjustment bolt 8
Reference numeral 4 extends from the other arm 78a of the first sleeve 78 along the direction of arrow C, and comes into contact with the other side surface of the arm 78a. Therefore, the first adjustment bolt 84
Restricts the rotation of the first sleeve 78 in the direction of arrow CC. The second adjusting bolt 85 extends from one of the arms 79a of the second sleeve 79 along the direction of the arrow CC, and abuts one side surface of the arm 79a.
Therefore, the second adjusting bolt 85 is connected to the second sleeve 7.
The rotation of arrow 9 in the direction of arrow C is restricted. Note that elastic members 97 are fixed to the ends of the adjusting bolts 84 and 85, respectively.

When the adjusting bolts 84 and 85 are rotated, the adjusting bolts 84 and 85 are displaced in the axial direction, so that the amount of protrusion of the adjusting bolts 84 and 85 with respect to the housing 26 can be changed. Therefore, the position of each of the arms 78a and 79a can be adjusted at the position in the rotational direction of the input shaft 11 in the straight traveling state of the vehicle (hereinafter, referred to as the straight traveling position), and the preload of the later described centering spring 76 is set to a desired value. Can be set.

A centering spring (hereinafter, simply referred to as a spring) 76 is a coil spring having a substantially rectangular cross section, and arms 78a, 79 of the sleeves 78, 79.
a. One end of this spring 76
The other end is connected to the anchor pin 95 on the first sleeve 78 side.
The anchor pins 95 on the sleeve 79 side are respectively locked.

The spring 76 has a predetermined preload when the input shaft 11 is in a straight-forward position, and presses the arm 78a of the first sleeve 78 in the direction of arrow CC to press the arm 78a against the first adjustment bolt 84. , Second sleeve 7
The arm 79a of No. 9 is pressed in the direction of arrow C and pressed against the second adjustment bolt 85. When the input shaft 11 rotates in the direction of arrow C, the spring 76 pushes the first sleeve 7 pressed against the first eccentric plate 81.
When the input shaft 11 rotates in the direction of arrow CC while being elastically deformed by the arm 78a of the
It is elastically deformed by the arm 79a of the second sleeve 79 pressed by 2.

Next, the operation of the rear wheel steering device 10 will be described. For example, when the steering wheel 4 is operated to the right to turn the vehicle to the right, the rack 6 of the front wheel steering device 1 is displaced in the direction of arrow A in FIG. 1 and the direction of the front wheels 2 is changed to the right. When the rack 6 is displaced in the direction of arrow A, the input shaft 11 rotates in the direction of arrow C, and the drive gear 24 rotates in the same direction to rotate the driven gear 45 in the direction of arrow CC. Therefore, the rotor 35 and the inscribed cam 36
Rotates in the direction of arrow CC.

FIG. 4 shows the positional relationship between the inscribed cam 36 and each roller 37. FIG. 4A shows the inscribed cam 3 when the steering wheel 4 is not operated and the vehicle goes straight.
6 shows the positional relationship between the roller 37 (ie, the inscribed cam at the straight traveling position) and the roller 37. In this state, each roller 37
It is in contact with the inactive portion 51 of the cam surface 36a,
The axial displacement of each roller 37 is zero.

When the inscribed cam 36 rotates in the direction of arrow CC from the straight traveling position, each roller 37 rolls along the cam surface 36a while the left roller 37 is moved to the first position on the cam surface 36a.
The right roller 37 reaches the convex portion 52 and reaches the second concave portion 55 of the cam surface 36a (FIG. 4B). Accordingly, each roller 37 moves rightward by the distance L1, and the steering shaft 12 is displaced in the direction of arrow B (rightward) in FIG.
And the rear wheel 74 is steered to the right side, that is, in the same phase through the knuckle arm 73.

Further, when the steering wheel 4 is steered rightward and the inscribed cam 36 rotates in the direction of the arrow CC, each roller 37 rolls along the cam surface 36a, while the left roller 37 moves on the cam surface 36a. First recess 54
Then, the right rollers 37 reach the second convex portions 53 of the cam surface 36a, respectively (FIG. 4C). Therefore, each roller 37
Moves leftward by the distance L2, the steering shaft 12 is displaced in the direction of arrow A (leftward) in FIG. 1, and the rear wheel 74 is steered leftward, that is, in the opposite phase.

FIG. 10 shows the steering angle θf of the front wheel 2 and the rear wheel 74.
Of the steering angle θr. Steering angle θf of front wheel 2
Increases in proportion to the rotation angle θs of the steering wheel 4. On the other hand, when the rotation angle θs of the steering wheel 4 increases, the steering angle θr of the rear wheels 74 first increases toward the same phase as described above. Then, when the rotation angle θs of the steering wheel 4 reaches the angle θ1, the relationship between the inscribed cam 36 and each roller 37 is in the state shown in FIG. 4B, and the steering angle θr of the rear wheel 74 is in the same phase. Is the largest. Further, when the rotation angle θs of the steering wheel 4 increases, the steering angle θr of the rear wheel 74 starts to decrease on the same phase side.

When the rotation angle θs reaches the angle θ2, the roller 37 on the left side of the inscribed cam mechanism 13 is
The roller 37 on the right side reaches a position corresponding to the virtual reference circle D between the second concave portion 55 and the second convex portion 53. Reach the site. Accordingly, each roller 37 returns to the position of each roller 37 shown in FIG. 4A, and the steering angle θr of the rear wheel 74 becomes zero.

From this state, when the rotation angle θs of the steering wheel 4 further increases, the steering angle θr of the rear wheel 74 increases.
Starts to increase in the opposite phase. The concave distance of the first concave portion 54 constituting the cam surface 36a from the virtual reference circle D is set smaller than the projecting distance of the first convex portion 52 from the virtual reference circle D, and the virtual distance of the second concave portion 55 is set. The recess distance from the reference circle D is set smaller than the protrusion distance of the second convex portion 53 from the virtual reference circle D. Therefore, the steering angle θr of the rear wheel 74 is greatly increased in the opposite phase side as compared with the same phase side. When the steering wheel 4 is operated to the left, the rear wheel 74 moves in the opposite direction to the above case. Steered. That is, each roller 37 of the inscribed cam 36 is first displaced to the left in FIG. 4 to change the direction of the rear wheel 74 to the left, and then displaced to the right to change the direction of the rear wheel 74 to the right.

Accordingly, also in this case, similarly to the case described above, first, the rear wheel 74 is steered to the same phase side, and when the rotation angle θs of the steering wheel 4 reaches the angle θ1, the steering angle θr of the rear wheel 74 becomes The peak on the same phase side is reached. Thereafter, the steering angle θr of the rear wheel 74 decreases on the same phase side, and when the rotation angle θs of the steering wheel 4 reaches the angle θ2,
The rear wheel 74 goes straight. When the rotation angle θs of the steering wheel 4 further increases, the steering angle θr of the rear wheel 74 increases to the opposite phase.

On the other hand, the centering mechanism 14 is
Position 1 at the straight-ahead position. That is, in a state where the steering operation is not performed, each of the arms 78a and 79a of the first and second sleeves 78 and 79 is moved by the spring 76 to the first state.
And the arms 78a, 79a position the eccentric plates 81, 82, that is, the input shaft 11, at the straight-forward position via the first and second pressing pieces 87, 88. I do.

In this state, when the steering is operated and the input shaft 11 is rotated from the straight traveling position in the direction of arrow C in FIGS. 8 and 9, the pressing piece 87 of the first eccentric plate 81 is moved to the arm 78a of the first sleeve 78. Press. At this time, the arm 79a of the second sleeve 79 comes into contact with the second adjustment bolt 85, and the rotation in the direction of arrow C is restricted. Therefore, the spring 76 is elastically deformed, and the spring force increases in the upward direction in FIG. As a result, the spring force of the spring 76 presses the arm 78a of the first sleeve 78 in the direction of the arrow CC, and acts in a direction to return the first eccentric plate 81, that is, the input shaft 11, to its straight traveling position.

Similarly, when the input shaft 11 is rotated in the direction of arrow CC in the drawing from the straight traveling position, the pressing piece 88 of the second eccentric plate 82 is moved to the arm 79 of the second sleeve 79.
Press a. Since the arm 78a of the first sleeve 78 comes into contact with the first adjustment bolt 84 and is restricted from rotating in the direction of arrow CC, the spring 76 is elastically deformed in the opposite direction to the above case, and the spring force is reduced. It increases in the downward direction in FIG. Therefore, the spring force of the spring 76 presses the arm 79a of the second sleeve 79 in the direction of arrow C, and acts in a direction to return the second eccentric plate 82, that is, the input shaft 11, to its straight traveling position.

The centering mechanism 14 of the present embodiment includes an input shaft 11 that changes the rotation angle in accordance with the steering angle of the front wheels 2.
Attached to. Therefore, when the steering wheel 4 is not operated, the centering mechanism 14 is operated so that the rear wheel 74 is made to go straight. Each elastic member 9 fixed to each adjusting bolt 84, 85
7 is a case in which the adjusting bolts 84 and 85 are
a, 79a, while absorbing the impact when contacting it and preventing the generation of noise.

In the rear wheel steering device 10 of the present embodiment,
The rotation of the input shaft 11 is controlled by the inscribed cam mechanism 13
2 is converted to the displacement in the vehicle width direction.
As means for converting one rotation into a displacement of the steering shaft 12,
It is not limited to this.

[0047]

As described above, according to the rear wheel steering apparatus of the present invention, positioning by the centering mechanism is performed within the input shaft.
Since it works effectively only in the standing position, there is an excellent effect that malfunction of the centering mechanism can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a rear wheel steering device of a vehicle to which the present invention is applied.

FIG. 2 is a sectional view showing details of a main part of the rear wheel steering device in FIG. 1;

FIG. 3 is a schematic configuration diagram of the internal cam mechanism of FIG. 1 as viewed from the rear of the vehicle.

FIG. 4 shows a schematic configuration of the inscribed cam mechanism of FIG. 1;
Is a diagram showing a positional relationship between the cam surface and each roller at the straight traveling position, (b) is a diagram showing a positional relationship between the cam surface and each roller in a state where the rollers are steered to the same phase, and (c) is an opposite phase side. FIG. 4 is a diagram showing a positional relationship between a cam surface and each roller in a state where the steering wheel is steered.

FIG. 5 is a plan view showing the shaft rotation preventing mechanism of FIG. 1;

6 is a cross-sectional view of the shaft rotation preventing mechanism taken along a line VI-VI in FIG.

FIG. 7 is a sectional view showing the centering mechanism of FIG. 1;

8 is a sectional view taken along the line VIII-VIII in FIG.

FIG. 9 is a sectional view taken along the line IX-IX in FIG. 7;

FIG. 10 is a diagram showing a relationship between steering angles of front wheels and rear wheels of a vehicle equipped with the rear wheel steering device of FIG. 1;

11 is a diagram showing a relationship between a spring force of a spring of the centering mechanism of FIG. 7 and a rotation angle of an input shaft.

DESCRIPTION OF SYMBOLS 1 front wheel steering device 2 front wheel 10 rear wheel steering device 11 input shaft 12 steering shaft 14 centering mechanism 24 drive gear 26 housing 35 rotor 36 inscribed cam 37 roller 45 driven gear 74 rear wheel 76 centering spring 78a, 79a arm 81,82 Eccentric plate 84,85 Adjust bolt

Claims (1)

(57) [Claims] 1. An input shaft extending from a front wheel steering device of a vehicle and rotating in conjunction with steering of a front wheel, a steering shaft extending in a vehicle width direction and moving in a vehicle width direction to steer a rear wheel, and an input shaft. Means for converting the rotation of the steering shaft into a displacement in the axial direction of the steering shaft, a centering mechanism is provided in the middle of the input shaft, and the centering mechanism is provided outside the input shaft, Fixed against
A housing for rotatably supporting the input shaft with, disposed on the outer periphery of the hand the input shaft within the housing, one
One end is in one direction when viewed in the rotation direction of the input shaft, and the other end is in one direction.
A centering spring having a biasing force, respectively in the other direction, before the proximal end to the outer periphery of the input shaft is supported relatively rotatably
It extends radially fill power shaft, a first arm for engaging the end of said centering spring, before the proximal end to the outer periphery of the input shaft is supported relatively rotatably
Extends radially fill force shaft, and a second arm for engaging the other end of the centering spring, disposed in said housing, said centering scan purine
A first stopper for limiting rotation in one direction of the first arm against the urging force of the grayed, provided in the housing, the centering scan purine
A second stopper for limiting rotation in the other direction of the second arm against the urging force of the grayed, is fixed to the input shaft, the input shaft or the predetermined neutral position
A first pressing member that presses the first arm in the other direction against the elastic force of the centering spring when pivoted in Luo other direction, is fixed to the input shaft, the input shaft from the neutral position second that presses the second arm in one direction against the elastic force of the centering spring when <br/> is rotated in one direction
A rear wheel steering device for a vehicle, comprising: a pressing member.