JPH09328074A - Rear wheel steering device - Google Patents

Abstract

(57) [PROBLEMS] To provide a rear wheel steering device that can be arranged without being restricted by layout even if the rod diameter increases and that can reduce the manufacturing cost. SOLUTION: Stroke setting means for setting the stroke amount of a rod 46 and dust seal means for preventing infiltration of dust, muddy water, etc. into a rod case 44 accommodating the rod 46 are provided inside a rear wheel steering device. Provided. The stroke setting means includes a tip end portion of the offset shaft 42 that rotates in the vehicle width direction and a pair of inner walls 48 of the shaft engagement case 48 that is separated from the tip end portion in the vehicle width direction.
a and 48b, and the distance between the tip and the inner wall has the same dimension as the stroke amount to be set on the rod 46. Further, the dust seal means is locked in the rod case 44 accommodating the end portion side of the rod 46 in the vehicle width direction, and the lip-type elastic seal member 56 for closing the space between the rod case 44 and the rod 46. Composed by.

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 system for steering rear wheels, and more particularly to means for setting a stroke amount of a rod and preventing intrusion of dust, muddy water, etc. into the apparatus case. The present invention relates to a rear wheel steering device including means.

[0002]

2. Description of the Related Art A four-wheel steering system (4WS) equipped with a rear-wheel steering system that steers rear wheels in order to improve vehicle motion and vehicle behavior, as opposed to a front-wheel steering system that is steered by a driver's steering input. It has been known.

As the above-described rear wheel steering device, for example, an electric rear wheel steering device described in JP-A-4-8668 is
After having a hypoid pinion that rotates integrally with the output shaft of the electric motor, a hypoid gear meshed with the hypoid pinion, a hypoid gear wheel integrally formed with the hypoid gear, and a transmission mechanism that transmits the rotational force of the hypoid gear wheel to a rod. A wheel steering device, in which a spherical bearing is integrally provided on the output side of a hypoid gear wheel, the axis of the spherical bearing is eccentric with respect to the axis of the hypoid gear wheel, and one side of a stud shaft is fitted to the spherical bearing. This is a device for connecting the other side to a rod while transmitting the output of the electric motor to the rod and moving the rod in the vehicle width direction.

In the rear wheel steering system having the above structure, when the hypoid wheel rotates, the stud shaft that is eccentric to the hypoid wheel rotates, and the rod fitted to the stud shaft is in a direction other than the axial direction. Since the movement of the above is moved by the spherical bearing in the vehicle width direction, the rear wheels are steered via the suspension member connected to the end of the rod.

By the way, FIG. 11 shows a structure in which a suspension arm 6 is connected between a rod 2 which moves in the vehicle width direction of the above-mentioned rear wheel steering device and a wheel carrier 4 which rotatably supports a wheel. The suspension arm 6 transmits the steering force from the rod 12 to the wheel carrier 4 and receives the weight of the vehicle body via the supporting spring (coil spring) 8.

An eyebolt 12 having a joint portion 12a connected to the suspension arm 6 is formed at an end portion of the rod 2 which moves in the vehicle width direction inside the rod case 10.
The eyebolt 12 is prevented from being loosened by a stopper member 14 that also serves as a lock nut and is formed to have a larger diameter than the outer circumference of the end 10a of the rod case 10.

A dust cover 16 made of synthetic resin or the like is mounted between the outer peripheral end of the rod case 10 and the joint 12a side of the eyebolt 12 with the end of the rod 2 and the stopper member 14 covered. Has been done.

When the rod 2 moves in the vehicle width direction and transmits the steering force to the wheel carrier 4, the stopper member 14 abuts on the end portion 10a of the rod case 10 to reduce the stroke amount of the rod 2. Regulated. Further, the dust cover 16 prevents dust and muddy water from coming into contact with the rod 2 sliding in the rod case 10.

[0009]

By the way, the suspension arm 6 receives the weight of the vehicle body through the bearing spring 8, but the rod 2 connected to the suspension arm 6 through the eyebolt 12 also receives the weight of the vehicle body. Some will be added. Therefore, the diameter of the rod 2 is set to be large in order to prevent the rod 2 from locally sliding in the rod case 10 due to the force in the bending direction acting on the rod 2.

However, when the rod diameter of the rod 2 becomes large, the outer diameter of the stopper member 14 that regulates the stroke amount of the rod 2 must be increased, and in accordance with the increase of the outer diameter of the stopper member 14. The outer diameter of the dust cover 16 also increases, which is disadvantageous in layout. That is, for example, the dust cover 16 must be arranged at a position sufficiently separated from the exhaust pipe arranged at the rear part of the vehicle body. Further, if a sufficient distance cannot be maintained with respect to the exhaust pipe, a dust cover made of a material that can withstand the high heat of the exhaust pipe must be selected, which causes a problem of high manufacturing cost.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned prior art, and even if the rod diameter increases, the rods can be arranged without being restricted by the layout, and the manufacturing cost can be increased. It is an object of the present invention to provide a rear wheel steering device capable of reducing

[0012]

In order to achieve the above object, a rear wheel steering system according to claim 1 is provided in a device case.
A rotary drive unit whose rotary shaft faces the front-rear direction of the vehicle body, a spherical bearing which is integrally arranged in the rotary drive unit around an axially eccentric position with respect to the rotary shaft, and one end of this spherical bearing. An offset shaft that is connected and extends substantially parallel to the rotation axis and a rod that is connected to the other end of the offset shaft and that extends in the vehicle width direction are housed, and rotation of the rotation drive unit is performed by the spherical surface. It is transmitted to the offset shaft via a bearing, and the rod is stroked in the vehicle width direction in conjunction with the rotation of the offset shaft in the vehicle width direction about the rotation axis, and the rod is stroked in the vehicle width direction according to the stroke amount of the rod. In a rear wheel steering device in which a rear wheel is steered via a suspension arm, a stroke setting means for setting a stroke amount of the rod, and the rod accommodating the rod. The dust seal means for preventing intrusion of dust and muddy water into the location case, provided in the apparatus case.

According to a second aspect of the present invention, in the rear wheel steering system according to the first aspect, the stroke setting means includes a tip of the other end of the offset shaft that rotates in the vehicle width direction, and the tip thereof. On the other hand, a pair of inner walls of the device case are separated from each other in the vehicle width direction, and the distance between the tip and the inner wall has the same dimension as the stroke amount to be set.

According to a third aspect of the present invention, in the rear wheel steering device according to the first or second aspect, the dust sealing means is constituted by an annular lip-type elastic seal member, and the lip-type elastic seal member is the above-mentioned. The rod is locked in an apparatus case accommodating the end portion of the rod in the vehicle width direction, and the lip formed on the inner peripheral side of the lip type elastic seal member is elastically deformed in the radial direction. Was brought into contact with the outer peripheral surface of the.

Further, the invention according to claim 4 is the same as claim 1.
Alternatively, in the rear wheel steering device according to the second aspect, the dust seal means is configured by an outer ring member, an inner ring member, and an annular elastic seal member joined between the outer ring member and the inner ring member, The outer ring member is locked in the device case that houses the end portion side in the width direction, and the inner ring member is locked on the outer periphery of the rod.

[0016]

According to the rear wheel steering system of claim 1,
For example, if the structure is such that the suspension arm bears the vehicle body weight via a spring, a part of the vehicle body weight is also added to the rod connected to the suspension arm, so that the influence of the bending direction force acting on the rod is eliminated. The diameter of the rod must be increased. Therefore, in the present invention,
In the conventional device, the stroke of the rod was replaced by a stopper member that was placed at the end of the rod to set the stroke amount of the rod and a dust cover that was placed so as to cover the connecting portion of the rod and the suspension arm. Stroke setting means for setting the amount and dust sealing means for preventing intrusion of dust, muddy water, etc. into the device case accommodating the rod are provided in the device case. As a result, even if the diameter of the rod is increased, there is no component such as the stopper member or the dust cover whose outer diameter is increased, and the exhaust pipe is disposed at the rear part of the vehicle like the dust cover. There are no parts that must maintain a sufficient distance. Therefore, it is possible to reduce the manufacturing cost as well as to eliminate layout restrictions.

According to the second aspect of the present invention, the stroke setting means includes a tip of the other end of the offset shaft that rotates in the vehicle width direction, and a stroke amount to be set in the vehicle width direction with respect to the tip. It is composed of a pair of inner walls of the device case that are separated by the same size. When the offset shaft is rotated to the right side in the vehicle width direction, for example, to the right in the vehicle width direction from the position where the tip end of the offset shaft is separated from the pair of inner walls by the same dimension as the stroke amount, the rod is interlocked with the vehicle width when the offset shaft is rotated rightward in the vehicle width direction. Move to the right in the direction. At this time, the tip end of the offset shaft comes into contact with one inner wall located on the right side in the vehicle width direction to restrain the movement, so that the stroke amount of the rod to the right side in the vehicle width direction is set.

Further, when the offset shaft rotates to the left side in the vehicle width direction due to the rotation output on the opposite side of the rotation drive unit, the rod also moves in conjunction with the left side in the vehicle width direction. At that time, since the tip end of the offset shaft abuts on the other inner wall located on the left side in the vehicle width direction to restrain the movement, the stroke amount of the rod to the left side in the vehicle width direction is set.

In this way, the stroke amount of the rod can be set only by engaging the tip of the offset shaft that rotates in the vehicle width direction with the pair of inner walls of the device case, which results in a simple device structure. The effect described in the item 1 can be obtained, and the manufacturing cost can be further reduced.

According to a third aspect of the present invention, the dust sealing means is constituted by an annular lip-type elastic seal member, and the lip-type elastic seal member accommodates the end portion side of the rod in the vehicle width direction. The rod is locked inside the device case, and the lip formed on the inner peripheral side of the lip-type elastic seal member is brought into contact with the outer peripheral surface of the rod while being elastically deformed in the radial direction. Since the lip slides in close contact with the outer peripheral surface of the rod when making a stroke, even with a simple structure, it is possible to reliably prevent dust, muddy water, etc. from entering the device case.

Further, as compared with the conventional device, the work of disposing the dust cover at the connecting portion between the rod and the suspension arm is not necessary, so that the work efficiency can be improved. And the effect of claim 1 or 2 can also be obtained.

According to a fourth aspect of the present invention, the dust seal means comprises an outer ring member, an inner ring member, and an annular elastic seal member joined between the outer ring member and the inner ring member, The outer ring member is locked in the device case housing the end side of the rod in the vehicle width direction, and the inner ring member is locked on the outer periphery of the rod, and when the rod strokes, Since the gap between the device case and the rod is closed while the elastic seal member is in an elastically deformed state, it is possible to reliably prevent dust, muddy water, etc. from entering the device case even with a simple structure. Here, since the stroke amount of the rod of the rear wheel steering device is small, the elastic deformation amount of the elastic seal member is not so large, and the durability of the elastic seal member is not affected.

Further, as compared with the conventional device, the work of disposing the dust cover at the connecting portion between the rod and the suspension arm is not necessary, so that the work efficiency can be improved. Furthermore, since there is no portion that slides on the rod, durability against wear can be improved. And the effect of claim 1 or 2 can also be obtained.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a rear wheel steering system according to the present invention will be described below with reference to FIGS. 1 to 10. The same components as those shown in FIG. 11 will be assigned the same reference numerals and explanations thereof will be omitted.

FIG. 1 shows an actuator unit 20 which constitutes a rear wheel steering system using an electric motor as a power source, and FIG. 2 is a perspective view showing main components of the actuator unit 20.

In the unit case 22 as the device case of the actuator unit 20, a bearing member 24a,
A hypoid gear pinion shaft 26, which is rotatably supported by 24b and has a hypoid pinion 26a formed on the outer periphery thereof, is disposed. Further, the hypoid gear pinion shaft 26 has an electric motor 28 externally attached to the unit case 22.
The rotary shaft 28a of is coaxially coupled.

Further, in the unit case 22, a hypoid ring gear 30a is formed on one end side of the rotary shaft P ₁ facing the front-rear direction of the vehicle body, and a small diameter portion 30b is formed on the other end side of the rotary shaft as a rotary drive unit. Hypoid gear wheel 30
Is provided, and on the outer periphery of the small diameter portion 30b,
A bearing member 32 that rotatably supports the hypoid gear wheel 30 is provided. The hypoid ring gear 30 a meshes with the hypoid pinion 26 a of the hypoid gear pinion shaft 26.

Further, the support shaft 34 is fitted in the shaft center on one end side of the hypoid gear wheel 30, and the tip end portion of the support shaft 34 is provided at the penetrating portion of the cover member 36 mounted on the unit case 22 with the bearing member 38. It is rotatably supported via.

An offset shaft 42 is attached to the small diameter portion 30b of the hypoid gear wheel 30 via a spherical bearing 40. That is, FIG. 3 and FIG.
As shown in FIG. 3, the shaft center P ₂ of the spherical bearing 40 is set at a position eccentric to the rotation axis P ₁ of the hypoid gear wheel 30 by an eccentric amount e.
3, one end 42a of the offset shaft 42 is fitted with the axis P ₃ aligned with the axis ₃ .

Further, a rod case 44 as a device case extending in the vehicle width direction is integrally attached to the unit case 22, and a rod 46 is accommodated in the rod case 44. Then, the rod 46, the direction in the through hole 46a perpendicular to the axis P ₄ is formed, the offset shaft 42 is fitted in the through hole 46a.

Here, as shown in FIG. 1, since the rod 46 is fitted to the axial center position of the offset shaft 42, the other end portion 42 of the offset shaft 42 is inserted.
b is further projected to the front of the vehicle body from the connection position with the rod 46. The other end 42 of this offset shaft 42
A shaft engaging case 48 formed in a part of the rod case 44 accommodates b. This shaft engagement case 4
Although 8 is formed in a box shape as shown in FIGS. 1 and 5, the distance in the vehicle width direction between the outer circumference of the offset shaft 48 and the left inner wall 48a and the right inner wall 48b located in the vehicle width direction. Is set to a predetermined dimension S.

At the tip end side of the support shaft 34 fitted in the hypoid gear wheel 30, the electric motor 2 is moved from the rotation angle of the hypoid gear wheel and the offset shaft 42.
A rear wheel steering sensor 50 including a rotary potentiometer and the like for detecting the rotation angle of 8, that is, the actual rear wheel steering angle of the rear wheels is connected. In addition, the rod case 44 includes
A rear wheel steering sensor 52 including a linear potentiometer for detecting the actual rear wheel steering angle from the movement amount of the rod 46 in the vehicle width direction is externally attached. Of these, the former rear wheel steering sensor 50 serves as a main sensor, and the detected actual rear wheel steering angle is used for the rear wheel steering angle control. Further, the rear wheel steering sensor 52 serving as a sub sensor uses the detected actual rear wheel steering angle as comparison target data for detecting an abnormality in either one of the rear wheel steering sensors 50, 52.

By the way, the rod case 44 and the rod 4
As shown in FIG. 6, neither dust cover nor stopper member is provided at both ends in the width direction of 6. That is, although the threaded portion of the eyebolt 12 is screwed into the threaded hole 46c formed along the axis P ₄ of the end portion 46b of the rod 46,
The eye bolt 12 is prevented from being loosened by a lock nut 54 having a diameter substantially the same as the outer diameter of the rod 46. Therefore, the lock nut 54 does not function as a stopper member that sets the stroke amount of the rod 46, and the rod stroke setting means of the present embodiment includes the other end portion 42b of the offset shaft 42 and the shaft engagement case 48. I am configuring.

As an alternative part to the dust cover, an annular dust seal member 56 engaged with the inner circumference of the end of the rod case 44 prevents dust, muddy water, etc. from entering the rod case 44. That is, the dust seal member 56
Is a lip 56 having a U-shaped cross section on the inner peripheral side of the annular portion 56a.
It is an elastic member formed with b. Also, the rod case 44
A concave portion 44a that is continuous in the circumferential direction is formed on the inner periphery of the end portion of the, the annular portion 56a is fitted into the concave portion 44a, and the movement of the annular portion 56a in the axial direction is restrained by the annular locking member 58. Thus, the dust seal member 56 is attached to the inner circumference of the end of the rod case 44. Then, when the rod 46 is housed in the rod case 44, the lip 56b of the dust seal member 56 comes into close contact with the outer peripheral surface of the rod 46 while elastically deforming so that the U-shaped cross section is expanded.

According to the rear wheel steering system having the above structure, the hypoid gear pinion shaft 26 is driven by driving the electric motor 28.
Is rotated in the forward and reverse directions, the hypoid gear wheel 30 rotates from the state shown in FIG. 7A to the state shown in FIG. 8A or 9A due to the meshing of the hypoid pinion 26a and the hypoid ring gear 30a. . The offset shaft 42 is rotated about the axis P ₁ of the hypoid gear wheel 30 by the rotation of the hypoid gear wheel 30. At that time, since the axial center P ₂ of the spherical bearing 40 is eccentric to the axial center of the hypoid gear wheel 27 by the eccentric amount e, the offset shaft 4
2 is a rod 46 from the state shown in FIG. 7 (b) to the state shown in FIG. Is moved in the vehicle width direction.

That is, FIG. 7 is a normal state in which no rotational force is input from the hypoid gear wheel 30, and FIG. 8 is a steering force to the right in the vehicle width direction of the rod 46 as the hypoid gear wheel 30 rotates in the arrow direction. Is transmitted, FIG. 9 shows the hypoid gear wheel 3
9 is a schematic diagram showing a state in which the steering force to the left in the vehicle width direction is transmitted to the rod 46 by rotating 0 in the arrow direction opposite to that in FIG. 8.

From the normal state in which the distance in the vehicle width direction between the outer periphery of the offset shaft 48 in FIG. 7 and the left inner wall 48a and the right inner wall 48b located in the vehicle width direction is set to S, FIG.
When the hypoid gear wheel 30 rotates in the arrow direction as shown in (a), the spherical bearing 40 and the offset shaft 4
Since 2 moves to the right in the vehicle width direction while rotating, the rod 46 also moves to the right in the vehicle width direction. At that time,
As shown in (b), the other end portion 42b of the offset shaft 42, which constitutes the rod stroke setting means together with the shaft engagement case 48, contacts the right inner wall 48b. As a result, the rightward stroke of the rod 46 in the vehicle width direction is restricted.

From the normal state of FIG. 7 to FIG. 9 (a)
When the hypoid gear wheel 30 rotates in the direction of the arrow, the spherical bearing 40 and the offset shaft 42 move leftward in the vehicle width direction while rotating, so that the rod 46
Also moves to the left in the vehicle width direction. At that time, as shown in FIG. 9B, the other end portion 42b of the offset shaft 42 is
It contacts the left inner wall 48a of the shaft engagement case 48. As a result, the leftward stroke of the rod 46 in the vehicle width direction is restricted. Therefore, the rod 4 is displaced by the distance S in the vehicle width direction set between the outer circumference of the offset shaft 48 and the left inner wall 48a and the right inner wall 48b of the shaft engaging case 48.
Since 6 moves in the vehicle width direction, the distance S becomes a regulation stroke amount for regulating the stroke of the rod 46.

Then, the rod 4 is moved by the regulation stroke amount S.
When 6 moves in the rod case 44, the eyebolt 12 fixed to the end portion 46 a of the rod 44, the joint portion 1
Steering force is transmitted to the rear wheels via 2a, the suspension arm 6 and the wheel carrier 4. Here, in the annular dust seal member 56 mounted on the inner circumference of the end portion of the rod case 44, the rod 46 is elastically deformed by the lip 34b.
Since it is in close contact with the outer peripheral surface of the rod case, infiltration of dust, muddy water, etc. into the rod case 44 is prevented.

Therefore, in the structure in which the suspension arm 6 bears the weight of the vehicle body via the spring 8, the rod 46 connected to the suspension arm 6 also receives a part of the vehicle weight, so that the diameter of the rod 46 is increased. Must. Therefore, in the present embodiment, in the conventional device shown in FIG. 11, the dust cover is provided at the end of the rod 2 so as to cover the stopper member 14 and the connecting portion of the rod 2 and the suspension arm 6. 14, the other end 42b of the offset shaft 42 is housed in the shaft engagement case 48 to serve as a stroke setting means, and the dust seal member 5 is provided on the inner circumference of the end of the rod case 44.
6 was attached as a dust seal means.

As described above, the stroke means and the dust seal means are connected to the unit case 22 and the rod case 44.
Since it is provided inside, there is no part such as a stopper member or a dust cover whose outer diameter size is large unlike the conventional device even if the diameter of the rod 46 is increased. There are no parts that must maintain a sufficient distance from the installed exhaust pipe.
Therefore, there are no layout restrictions, and
Manufacturing costs can be reduced.

Further, in the stroke setting means in which the other end portion 42b of the offset shaft 42 is housed in the shaft engaging case 48, the hypoid gear wheel 30 rotates via the hypoid gear pinion shaft 26 by the drive of the electric motor 28, When the offset shaft 42 rotates, for example, to the right in the vehicle width direction, the rod 46 also interlocks and moves to the right in the vehicle width direction. At this time, the tip end of the offset shaft 42 contacts the right inner wall 48b of the shaft engagement case 48 to restrain the movement of the rod 46, so that the stroke amount of the rod 46 to the right in the vehicle width direction is set. Further, when the hypoid gear wheel 30 rotates in the reverse direction and the offset shaft 42 rotates to the left side in the vehicle width direction, the rod 46 also interlocks and moves to the left side in the vehicle width direction, and the tip end of the offset shaft 42 becomes the shaft engaging case 48. Since the movement of the rod 46 is restrained by contacting the left inner wall 48a of the rod 4,
A stroke amount to the left in the vehicle width direction of 6 is set.

Therefore, the stroke amount of the rod 46 can be adjusted only by engaging the tip end of the offset shaft 42, which rotates in the vehicle width direction, with the pair of inner walls 48a, 48b located in the vehicle width direction of the shaft engaging case 48. Since it can be set, the device structure becomes simple and the manufacturing cost can be reduced.

As a substitute for the dust cover, a dust seal member 56 is attached to the inner periphery of the end of the rod case 44, and the lip 56b is elastically deformed in the radial direction and brought into contact with the outer peripheral surface of the rod 46. Cage, rod 4
When 6 strokes, the lip 56b slides in close contact with the outer peripheral surface of the rod 46, so even if the structure is simple, it is possible to reliably prevent dust, muddy water, etc. from entering the rod case 44. .

Further, since the work of disposing the dust cover on the connecting portion of the rod 46 and the suspension arm 6 is not necessary, the work efficiency can be improved. next,
The one shown in FIG. 10 is an alternative part of the dust cover.
9 shows a modification of the dust seal member mounted on the inner circumference of the end of the rod case 44. The same components as those shown in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

The dust seal member 60 of the present embodiment is fitted in the outer ring member 60a fitted in the recess 44a formed in the inner circumference of the end of the rod case 44 and in the recess 46d formed in the outer circumference of the end 46b of the rod 46. Inner ring member 60
b, and an annular elastic seal member 60c joined between the outer ring member 60a and the inner ring member 60b.

A ring groove is formed on the outer peripheral surface of the outer ring member 60a, and the O-ring 60 is formed in the ring groove.
The a ₁ is mounted to maintain the liquid tightness of the contact surfaces of the outer ring member 60a and the recess 44a. A ring groove is also formed on the inner peripheral surface of the inner ring member 60b, and an O-ring 60b ₁ is mounted in the ring groove to maintain liquid tightness of the contact surface between the inner ring member 60b and the rod 46. The outer ring member 60a and the inner ring member 60b are annular locking members 62, 6
The movement in the axial direction is restricted by 4.

Here, as the elastic seal member 60c, an elastic member that deforms in the elastic region with respect to the stroke of the rod 46 is selected. Since the stroke amount of the rod 46 of the rear wheel steering device is small, the elastic deformation area of the elastic seal member 60c is not so large.

According to the above construction, when the rod 46 moves in the rod case 44, the elastic seal member 50c is elastically deformed by the movement of the inner ring member 60b to the right or left in the vehicle width direction. As a result, no gap is generated between the rod case 44 and the rod 46, so that it is possible to prevent dust or muddy water from entering the rod case 44.

Further, since the stroke amount of the rod 46 of the rear wheel steering device is small, the elastic deformation amount of the elastic seal member 50c is not so large, and the durability of the elastic seal member is not affected.

Further, since the work of disposing the dust cover at the connecting portion between the rod 46 and the suspension arm 6 unlike the conventional device is unnecessary, the work efficiency can be improved. Further, the dust seal member 60 is attached to the rod 4
Since there is no part that slides with respect to 6, durability against wear can be improved.

It should be noted that although the position and the direction of movement have been described with respect to the respective parts by expressing the vehicle width direction, the vehicle front-rear direction, and the vertical direction, these indicate relative positions of the respective parts. Of course, in other embodiments, the absolute position and the direction of movement may be different from those described above.

[Brief description of drawings]

FIG. 1 is a view showing a rear wheel steering device of the present invention from above a vehicle body.

FIG. 2 is a perspective view showing main components constituting an actuator unit of the rear wheel steering system.

FIG. 3 is a diagram showing a state in which a hypoid gear wheel and an offset shaft forming an actuator unit are eccentrically connected to each other from a vehicle body rear side.

FIG. 4 is a view showing a spherical bearing connected between a hypoid gear wheel and an offset shaft and a rod connected to the offset shaft in a vehicle width direction.

5 is a view taken along the line V-V in FIG.

FIG. 6 is a diagram showing an embodiment in which a suspension arm is connected to a rod of a rear wheel steering device from the rear side of the vehicle body.

FIG. 7 is a schematic diagram showing an arrangement of an offset shaft and a shaft engaging case in a normal state in which a rotational force is not input from a hypoid gear wheel.

FIG. 8 is a schematic diagram showing an arrangement of an offset shaft and a shaft engagement case when the rod moves to the right in the vehicle width direction by rotation of a hypoid gear wheel.

FIG. 9 is a schematic diagram showing an arrangement of an offset shaft and a shaft engaging case when the rod moves to the left side in the vehicle width direction by the rotation of the hypoid gear wheel.

FIG. 10 is a view showing, from the vehicle body rear side, another embodiment in which a suspension arm is connected to a rod of a rear wheel steering system.

FIG. 11 is a view showing a conventional rear wheel steering device in which a stopper member and a dust cover are arranged between a rod and a suspension arm.

[Explanation of symbols]

4 Wheel Carrier 6 Suspension Arm 22 Unit Case (Device Case) 30 Hypoid Gear Wheel (Rotation Drive Unit) 40 Spherical Bearing 42 Offset Shaft 42a Offset Shaft One End 42b Offset Shaft Other End 44 Rod Case (Device Case) 46 Rod 48 Shaft engaging case 48a Left inner wall of shaft engaging case 48b Right inner wall of shaft engaging case 56 Dust seal member (lip type elastic seal member) 56b Lip 60 Dust seal member 60a Outer ring member 60b Inner ring member 60c Elastic seal member P ₁ Hypoid gear wheel Rotation axis P ₂ Axial center of spherical bearing P ₃ Axis of offset shaft S S Stroke amount

Claims (4)

[Claims] 1. A rotary drive unit in which a rotary shaft is oriented in the longitudinal direction of a vehicle body in a device case, and a spherical surface which is integrally arranged in the rotary drive unit with an axially eccentric position being eccentric to the rotary shaft. A bearing, an offset shaft having one end connected to the spherical bearing and extending substantially parallel to the rotating shaft, and a rod connected to the other end of the offset shaft and extending in the vehicle width direction are housed. , The rotation of the rotary drive unit is transmitted to the offset shaft via the spherical bearing, and the rod is stroked in the vehicle width direction in conjunction with rotation of the offset shaft in the vehicle width direction about the rotation axis. In the rear wheel steering device, wherein the rear wheels are steered via the suspension arm in accordance with the stroke amount of the rod, stroke setting means for setting the stroke amount of the rod, Rear wheel steering apparatus, wherein a dust seal means for preventing intrusion of dust and muddy water into the apparatus casing which houses the rod, provided within said device casing. 2. The stroke setting means includes a tip of the other end of the offset shaft that rotates in the vehicle width direction, and a pair of inner walls of the device case that are separated from the tip in the vehicle width direction. The rear wheel steering system according to claim 1, wherein the distance between the tip and the inner wall has the same dimension as the stroke amount to be set. 3. The dust seal means is constituted by an annular lip-type elastic seal member, and the lip-type elastic seal member is locked in an apparatus case accommodating an end side of the rod in the vehicle width direction. 3. The lip formed on the inner peripheral side of the lip-type elastic seal member is brought into contact with the outer peripheral surface of the rod while being elastically deformed in the radial direction. Wheel steering device. 4. The outer ring member, the dust seal means,
An inner ring member and an annular elastic seal member joined between the outer ring member and the inner ring member, and the outer ring member in a device case accommodating the end portion side of the rod in the vehicle width direction. 3. The rear wheel steering system according to claim 1, wherein the inner wheel member is locked to the outer circumference of the rod.