JPH10138943A - Rear wheel steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the number of parts by integrally mounting a detecting means for detecting the rotation of a motor and a controller in a case of the motor. SOLUTION: In case 16 of a motor 15 fastened to a gear box 2 by a bolt 28, a controller 30 for controlling the motor 15 by a signal on the vehicle side, and a hall element 31 as a sensor for detecting the position of a rod 6 from the rotation of the motor 15 are integrally housed, a resolver 32 for detecting the rotation to control the rotation of the motor 15 is mounted on one end of a motor shaft, covered with a cover 33, and connected to the controller 30. The cables other than a signal cable 34 and a power supply cable 35 to the controller 30, from the case 16 of the motor 15 are connected in a case 16. When the motor 15 is driven, a wheel nut 8 is rotated through a worm shaft 13, the rotational motion is converted into the linear motion of the rod 6, and a rear wheel is steered through a link connected to the rod 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering system, and more particularly to an improvement in a rear-wheel steering system suitable for use in an automobile.

[0002]

2. Description of the Related Art Conventionally, as related to a rear wheel steering system, for example, Japanese Patent Laid-Open Publication No.
Some are disclosed in the figures and will be described. In this rear wheel steering device, a motor is driven by a control device (not shown), and the rotation output is transmitted to a rod by a trapezoidal screw through a worm gear, and the rear wheel is steered through a link. The trapezoidal screw is fixed without transmitting the movement from the rod side to the motor side, so when the actuator breaks down, the rear wheel has a fail-safe mechanism that does not suddenly steer and detects the rod movement. The motor is driven and controlled by a controller (not shown) according to a signal from a stroke sensor (not shown).
The rod converts the rotation into a linear motion with a trapezoidal thread, and the rotation of the rod is restricted by a rotation preventing member.

[0003] Also, Japanese Patent Application Laid-Open No. 7-81591
Some are disclosed in the figures and will be described. The rear wheel steering device includes a backlash removing mechanism that removes backlash of a trapezoidal screw mechanism of the actuator. The backlash removing mechanism is formed on a movable member that abuts on the back surface of the female screw of the trapezoidal female screw member and on a housing. A screw member fixed to the screw hole, a compression coil spring interposed between the screw member and the movable member, and as a biasing means for pressing the movable member against the back surface, and a screw member with respect to the housing. The lock nut is a locking nut that stops, and prevents a tapping sound from being generated in the trapezoidal screw portion due to a fluctuating load from the tire side on a rough road.

[0004]

In the front rear wheel steering device, the actuator and the control device for controlling the motor are separated from each other, and the actuator and the control device are connected to the vehicle body. Must be provided separately, so that wiring, cables and connectors for connecting the actuator and the controller are required, the number of parts is increased, and a strobe for detecting the movement of the actuator is required. The structure in which the stroke sensor is provided outside the actuator requires a mechanism for attaching the stroke sensor and wiring, which increases the number of parts and increases the cost. Furthermore, in the rear wheel steering device, the backlash removing mechanism of the trapezoidal screw portion has a structure in which the rod and the trapezoidal screw are separately provided,
There is a problem that the mechanism is complicated, the outer diameter is increased, and the mountability on a vehicle is deteriorated.

Therefore, the present invention provides an actuator, a sensor, a control device, and the like integrally provided in a case to achieve compactness, simplify a backlash mechanism of a trapezoidal screw portion, and reduce costs. The object is to provide a wheel steering device.

[0006]

According to a first aspect of the present invention, a cap fastened to a gearbox, a rod supported by the gearbox and a support member provided on the cap and slidably fitted therein, and a rod formed therein. Which is screwed into the screw portion to be mounted and supported by a bearing member to be freely rotatably mounted.
Backlash removing means for removing the backlash by elastically pressing the threaded portion of the trapezoidal threaded portion of the rod and the wheel nut with the rod, and a backlash removing means for restricting the rotation of the rod. A detent means provided for engagement, a worm shaft supported by a bearing so as to mesh with a worm gear formed on a wheel nut, and a gear box connected to the worm shaft and driven to rotate. Motor to be concluded,
A rear wheel steering device comprising: a detecting means for detecting rotation of a motor; and a control device for controlling the motor based on the detecting means, wherein the detecting means and control for detecting rotation of the motor are provided. The device is integrally mounted in the motor case.

In the second invention, the backlash removing means comprises an elastic member fitted coaxially with the trapezoidal screw portion between a bearing provided at one end of the wheel nut and a plate press-fitted and fixed to the rod, and the rod and the wheel are removed. -The backlash is removed by elastically pressing the threaded portion of the trapezoidal threaded portion of the runt nut into pressure contact.

[0008] In the third aspect of the invention, the detent means engages a pin protruding from the cap with a notch provided in a plate press-fitted and fixed to the rod, thereby restricting rotation of the rod.

In the fourth invention, the backlash removing means comprises: a main screw portion and a sub screw portion formed on the rod;
A wheel nut screwed into the main screw portion and supported by the bearing member and rotatably mounted; a sub nut screwed into the sub screw portion and spline-coupled to the wheel nut; and an inner diameter portion of the sub nut and the wheel nut An elastic member is inserted between the rods, and the rod and the threaded threaded portions of the trapezoidal threaded portions of the wheel nut and the sub nut are elastically pressed into contact with each other to remove backlash.

[0010] In the fifth aspect, the rotation preventing means inserts and engages the rotation preventing plug screwed into the threaded portion provided on the gear box into the groove provided on the rod, thereby restricting the rotation of the rod.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the rear wheel steering device according to this embodiment has a main body 1 including a cap 4 that is fastened to a gear box 2 with bolts 3. Both ends are supported by the bush 5 and the rod 6 is slidably fitted therein.

A trapezoidal thread 6c is formed on the rod 6, and a trapezoidal thread 8c formed on the wheel nut 8 is screwed to the trapezoidal thread 6c.

The wheel nut 8 has a worm gear 8b formed on an annular convex portion 8a outside the wheel nut 8, and a bush 9 provided on a small inside diameter portion 2a in the gear box 2 and a large inside diameter portion. It is supported by a bearing 10 provided in 2b and is rotatably mounted.

The worm gear 8b of the wheel nut 8 meshes with a worm shaft 13 supported by a bush 11 and a bearing 12 provided on the gear box 2.

The worm shaft 13 is connected to a gear box 2 via a joint 14 by a motor 15
Shaft 15a.

A rod selection portion 6b is formed on the rod 6 at a position from the cap 4 side at a certain distance from the trapezoidal screw portion 6c, and the rod selection portion 6b has a notch 17a. The plate 17 is press-fitted and fixed.

The notch 17a of the plate 17 is engaged with a pin 18 protruding from the cap 4, and the rod 6 is rotated by the frictional force of the trapezoidal threads 6c and 8c caused by the rotation of the wheel nut 8. The rotation preventing means 19 is configured so as not to be performed.

A thrust bearing 20 fitted to the rod 6 is mounted on one end surface 8f of the wheel nut 8, and the shaft 22 of the trapezoidal screw portion 6c is interposed between the thrust bearing 20 and the plate 17 via a spring receiver 21. A compression coil spring 23 as an elastic member is interposed coaxially.

The spring 23 urges the rod 6 in one direction via the plate 17.
Backlash removing means 25 for removing the backlash between the trapezoidal screw portions 6c and 8c by elastically pressing the threaded portion 24 of the trapezoidal screw between the wheel nut 8 and the wheel nut 8.

In a case 16 of the motor 15 fastened to the gear box 2 by bolts 28, there are provided a control device 30 for controlling the motor 15 by a signal from a vehicle (not shown) and a motor 15.
Is a sensor that detects the position of the rod 6 from the rotation of
A resolver 32 for integrally detecting a rotation of the motor 15 is mounted on one end of the motor shaft 15a and covered with a cover 33. 30.

From the case 16 of the motor 15, the control device 3
Only the signal cable 34 and the power cable 35 to 0 protrude, and the other connections are connected within the case 16.

When the motor 15 is driven, the wheel nut 8 having the worm gear 8b is rotated via the worm shaft 13, and the rotational movement of the wheel nut 8 is controlled by the trapezoidal thread portion 8c. , And the rear wheels are steered via a link (not shown) connected to the rod 6.

Next, the operation will be described. Now, if a signal (not shown) (vehicle speed, steering angle, yaw rate, etc.) is input from the vehicle side to the control device 30, the motor 15
Is driven by a sensor such as the resolver 32 or the like.
The rotation of the motor 15 is detected, and the rotation of the motor 15 is controlled.

Then, the joint 14 is attached to the motor shaft 15a.
The worm meshed with the worm shaft 13 joined by
And the wheel nut 8 rotates by being reduced by the
The wheel nut 8 and the trapezoidal threaded portions 8c, 6c of the rod 6 are screwed together to convert the rotational motion of the wheel nut 8 into a linear motion of the rod, and the stroke of the rod 6 is used as a sensor ball. The element 31 detects the rotation speed of the motor 15 and is connected to the rear wheel via a link (not shown) at both ends of the rod 6 so that the output signal from the control device 30 can be used in response to a signal from the vehicle. Turn the wheels.

Therefore, when the rear wheel is steered, the action of the backlash removing means of the fitting portion 24 of the trapezoidal threaded portion between the rod 6 and the wheel nut 8 when the rod 6 receives an external force f from the road surface or the like. See about.

Considering the case where the rod 6 strokes in the leftward direction L in the drawing, as shown in FIG. 3A, the trapezoidal thread 6c of the rod 6 and the trapezoidal thread of the wheel nut 8 are used. 8c is screwed into the wheel nut 8 and the pre-
The rod 6 is urged in the direction R on the right side in the figure by a spring 23 interposed between the
6d is the trapezoidal thread 8c of the wheel nut 8.
A right-hand threaded surface 8d, and is kept free of backlash between the two.

In this state, if the wheel nut 8 rotates clockwise because the rod 6 strokes in the left direction L in the figure, the rotation of the wheel nut 8 causes the wheel to rotate.
The right-hand thread surface 8d of the trapezoidal thread portion 8c of the nut 8 comes into contact with the right-hand thread surface 6d of the trapezoidal thread portion 6c of the rod 6, and rotation is transmitted, whereby the rod 6 strokes in the left direction L.

At this time, even if a random force f due to a change in the road surface acts through a link (not shown) from the side of the broken arrow shown in FIG. 3A, the rod 6, the wheel nut 8, the bearing 10, the gear Since there is no backlash between the boxes 2, rattling noise called rattle sound does not occur.

Further, the rod 6 moves in the right direction R in the drawing.
In this case, the trapezoidal thread 6c of the rod 6 and the trapezoidal thread 8c of the wheel nut 8 are screwed together as shown in FIG. The rod 6 is urged in the right direction R in the figure by a spring 23 interposed between the right-hand thread surface 6 and the trapezoidal thread portion 6 c of the rod 6.
d and right-hand thread surface 8 of trapezoidal thread portion 8c of wheel nut 8
It is in contact with d.

On the other hand, the left-hand thread surface 6e of the trapezoidal thread portion 6c of the rod 6 and the left-hand thread surface 8e of the trapezoidal thread portion 8c of the wheel nut 8 are maintained in an initial state with a backlash h between them. In this state, the rod 6 rotates in the right direction R in the drawing, so that the wheel nut 8 rotates counterclockwise, and the load r acting from the right side R of the rod 6 causes the trapezoidal thread portion of the rod 6 to rotate. After filling the backlash h between the left thread surface 6e of the rod 6c and the left thread surface 8e of the trapezoidal thread portion 8c of the wheel nut 8, the left thread surface 6e of the trapezoidal thread portion 6c of the rod 6 and the wheel nut 8 are filled. Abuts on the left-hand thread surface 8e of the trapezoidal threaded portion 8c.

Then, while being in contact with the wheel nut 8,
Is rotated, the rod 6 strokes in the leftward direction L.

At this time, even if a random force f due to a change in the road surface acts via a link (not shown) from the side of the broken arrow shown in FIG. 3 (c), the rod 6, the plate 17, the spring 23,
Since there is no backlash between the wheel nut 8, the bearing 10 and the gear box 2, no rattling noise is generated.

As described above, the controller 30 for controlling the motor 15 and the sensors 31 and 32 for detecting the rotation of the motor 15
Are housed in the case 16 of the motor 15 and integrated, so that it is not necessary to separately install the motor drive unit and the control device, which are actuators, on the vehicle body, and the vehicle is mounted on the vehicle. In addition, the number of parts such as wiring, cables and connectors for connecting the motor drive unit and the control device can be reduced, and a sensor for detecting the movement of the motor drive unit is provided. The structure provided inside the simplifies installation and wiring of the stroke sensor, reduces the number of parts and assembly steps, reduces costs, and protects the sensor from dust and damage caused by stepping stones from the road surface. .

Further, since the backlash removing means 25 for removing the backlash of the trapezoidal thread portions 6c, 8c of the rod 6 and the wheel nut 8 is provided on the shaft 22 of the rod 6, the conventional backlash removing mechanism is provided. Compared with this, the mechanism is simpler, the number of parts is smaller, the outer diameter dimension is smaller, the size is smaller, and furthermore, it is possible to prevent rattle noise.

The rod 6 has a rod selection section 6.
b, a notch 1 is formed in the rod selection portion 6b.
A plate 17 having a plate 7a is press-fitted and fixed, and a notch 17a of the plate 17 is engaged with a pin 18 protruding from the cap 4 so that a detent means 19 is prevented from rotating the rod 6. With this configuration, the pin 18 engages with the notch 17a provided in the plate 17 when the rod 6 is about to rotate due to the frictional force between the trapezoidal screw portion 8c and the trapezoidal screw portion 6c due to the rotation of the wheel nut 8. Therefore, the rotation of the plate 17 can be restricted to prevent the rotation of the rod 6, and the use of the plate 17 configured as the backlash removing means can reduce the number of parts and reduce the cost.

Next, the second embodiment shown in FIG.
Only the configuration of the backlash removing means for removing the backlash of the trapezoidal thread portion between the rod and the wheel nut and the configuration of the detent means for preventing the rod from rotating due to the frictional force of the trapezoidal thread portion due to the rotation of the wheel nut are shown. The other points are the same as those of the first embodiment. Here, only the different configuration will be described, and the details of the other components will be omitted.

Therefore, in the rear wheel steering device according to the second embodiment, the bush 5 provided on the gear box 2 and the cap 4 is provided.
The main trapezoidal thread portion 6f and the sub trapezoidal thread portion 6i are formed on the rod 6, which is supported at both ends and slidably fitted therein, and the trapezoidal shape of the wheel nut 40 is formed on the main trapezoidal thread portion 6f. The screw portion 40f is screwed into the sub-trapezoidal screw portion 6i with the trapezoidal screw portion 41i of the sub nut 41.

The sub nut 41 is connected to the wheel nut 40 and a spline 41b at one end 41a of the wheel nut 40.

A spring 43 is interposed between the inner diameter portion 40a of the wheel nut 40 and the sub nut 41 coaxially with the shaft 22 of the trapezoidal screw portion 6f, and the trapezoidal screw portion 41i of the sub nut 41 and the sub trapezoidal screw are provided. Part 6i and wheel nut 4
The trapezoidal thread 40f and the main trapezoidal thread 6f are urged so as to abut each other, so that the threaded portions 42a and 42b of the trapezoidal screw with the wheel nut 40 and the sub nut 41 are elastically pressed into contact with each other. And the trapezoidal thread 4 of the sub nut 41
1i, the sub-trapezoidal thread 6i, and the backlash removing means 48 for removing the backlash between the trapezoidal thread 40f of the wheel nut 40 and the main trapezoidal thread 6f.

The wheel nut 40 is a wheel nut 4
A worm gear 44 is fitted and fixed to an outer annular portion 40b of the gear box 2 and is supported by a bearing 45 provided on the large inner diameter portion 2b in the gear box 2 and a bush 46 provided on the inner diameter portion 4a of the cap 4. , And are rotatably mounted.

The worm gear 44 of the wheel nut 40 meshes with the worm shaft 13 supported by the bush 11 and the bearing 12 provided on the gear box 2.

The rod 6 is provided with a detent groove 6m, into which a detent plug 47 for screwing into a screw hole 2d provided in the GABOX 2 is inserted. Rotation of the trapezoidal thread 4
The detent means 49 is configured to detent so that the rod 6 is not rotated by the frictional force between 0f and 6f and between 40i and 6i.

Next, the operation will be described. Signals not shown from the vehicle side (vehicle speed, steering angle, yaw rate
) Is input to the control device and the motor 15 is driven, and the motor 15 is decelerated by the worm gear 44 meshing with the worm shaft 13 connected to the motor shaft 15a by the joint 14, so that the wheel nut is driven. 40 rotates.

The rotation of the wheel nut 40 causes the rod 6
When the stroke is performed in the leftward direction L in the drawing, the operation of the backlash removing means 48 of the trapezoidal thread portion of the rod 6, the wheel nut 40, and the sub nut 41 will be described.

As shown in FIG. 5, the main trapezoidal thread 6f of the rod 6 and the trapezoidal thread 40f of the wheel nut 40,
The sub-trapezoidal screw portion 6i of the rod 6 and the trapezoidal screw portion 41i of the sub-nut 41 are screwed together, and the wheel nut 4
The right screw surface 6h of the main trapezoidal screw portion 6f of the rod 6, the right screw surface 40h of the trapezoidal screw portion 40f of the wheel nut 40, and the sub-trapezoidal screw portion 6i of the rod 6 are provided by a spring 43 interposed between the sub nut 41 and the sub nut 41. The left-hand thread surface 6k and the left-hand thread surface 41k of the trapezoidal thread portion 41i of the sub-nut 41 abut against each other, so that there is no backlash between them.

In this state, if the wheel nut 40 rotates clockwise because the rod 6 strokes in the left direction L in the drawing, the rotation of the wheel nut 40 causes the main trapezoidal threaded portion of the rod 6 to rotate. 6f right side screw surface 6h and trapezoidal screw portion 40f of wheel nut 40 right side screw surface 40f
h, with the wheel nut 40 and the left screw surface 41k of the trapezoidal screw portion 41i of the sub nut 41 engaged with the spline 41b engaged with the wheel nut 40 and the left screw surface 6k of the sub trapezoidal screw portion 6i of the rod 6 in contact with each other. The sub-nut 41 rotates together with the sub-nut 41, and the rotation is transmitted to the trapezoidal thread portion, so that the rod 6 strokes in the left direction L.

The rod 6 moves in the right direction R in the drawing.
5, the right-hand thread surface 6h of the main trapezoidal thread portion 6f of the rod 6 and the right-hand thread surface 40h of the trapezoidal thread portion 40f of the wheel nut 40 are in contact with each other, as shown in FIG.
In this state, there is no backlash between the two. In this state, when the wheel nut 40 rotates counterclockwise because the rod 6 strokes in the right direction R in the drawing, the wheel nut 40 is rotated. By rotation, the right-hand thread surface 6h of the main trapezoidal thread portion 6f of the rod 6, the right-hand thread surface 40h of the trapezoidal thread portion 40f of the wheel nut 40, the left-hand thread surface 6k of the sub-trapezoidal thread portion 6i of the rod 6 and the trapezoid of the sub-nut 41 are formed. With the left screw surface 41k of the screw portion 41i in contact, the wheel nut 40 and the sub nut 41 rotate integrally,
The rotation is transmitted to the trapezoidal thread and the rod 6 moves in the right direction R.
Stroke.

When the rod 6 strokes in either the left or right direction in the drawing, even if a random force due to a road surface change acts from either the left or right side of the rod via a link (not shown), the rod 6 Since there is no backlash between the sub nut 41, the wheel nut 40, the bearing 45, and the gearbox 2, no rattling noise is generated.

Further, when the rod 6 tries to rotate due to the frictional force of the main trapezoidal thread 6f and the sub-trapezoidal thread 6i due to the rotation of the wheel nut 40 and the sub-nut 41, the rod 6 is provided with a detent groove 6m. The anti-rotation plug 47 which is screwed into the screw hole 2c provided in the gabox 2 is inserted into the anti-rotation groove 6m, and the anti-rotation plug is prevented from rotating.
Does only linear motion.

As described above, the main trapezoidal thread portion 6f and the sub trapezoidal thread portion 6i are formed on the rod 6, and the trapezoidal thread portion 40f of the wheel nut 40 is formed on the main trapezoidal thread portion 6f.
The sub-trapezoidal screw portion 6i is screwed with the trapezoidal screw portion 41i of the sub-nut, and a spring 43 is interposed between the sub-nut 41 to be connected to the whip nut 40 and the spline 41b. 6g, 6h
And the screw surfaces 6j and 6i of the sub-trapezoidal thread are in contact with the threaded surfaces 40g and 40h of the trapezoidal threaded portion of the wheel nut 40 and the threaded surfaces 41j and 41k of the trapezoidal threaded portion of the sub-nut 41. 6 can be output without backlash together with the output in both the left and right directions, no rattling sound called rattling sound is generated, and the responsiveness can be significantly improved.

A rotation-preventing plug 45 screwed into the screw hole 2c provided in the gabox 2 is inserted into the rotation-preventing groove 6m provided in the rod 6, and the screw of the trapezoidal screw portion is rotated by the rotation of the wheel nut 40. The anti-rotation means 49 is configured to prevent the rod 6 from rotating due to the frictional force at the joint portions 42a and 42b. Therefore, the anti-rotation plug 47 for restricting the anti-rotation of the rod 6 can be replaced or removed as necessary. Can be easily done.

[0052]

According to the first aspect of the invention, the control device for controlling the motor is housed and integrated in the case of the motor. There is no need to separately install the actuator and control device on the vehicle body,
It is easy to mount on a car, the number of parts such as wiring and cables and connectors for connecting the actuator and the control device can be reduced, and the sensor for detecting the movement of the actuator is also a cable. Since the structure is provided inside the sensor, the mounting mechanism and wiring of the stroke sensor are simplified, the number of parts can be reduced, the cost can be reduced, and the sensor can be protected from dust and damage from flying stones from the road surface.

According to the second aspect of the present invention, since the backlash removing means for removing the backlash of the trapezoidal threaded portion between the rod and the wheel nut is provided on the rod shaft, the mechanism is smaller than the conventional backlash removing mechanism. Is easy,
The number of parts is small, the outer diameter dimension is small and the size is small, and furthermore, the hitting sound called rattle noise can be prevented, and the durability can be improved.

According to the third aspect of the present invention, the rod selection portion is provided on the rod, and a plate having a notch portion is press-fitted and fixed in the rod selection portion. Since the rotation preventing means is constituted so as to prevent the rod from rotating by engaging with the protruding pin,
Even if the rod tries to rotate due to the frictional force of the trapezoidal thread part due to the rotation of the nut, the pin engages with the notch provided in the plate and the rotation is restricted by the pin, so that it does not rotate. By using, the number of parts is small and the configuration can be simplified.

According to the fourth aspect of the present invention, the main trapezoidal thread portion and the sub-trapezoidal thread portion are formed on the rod, and the main trapezoidal thread portion has the trapezoidal thread portion of the wheel nut and the sub-trapezoidal thread portion has the trapezoidal shape of the sub-nut. The main trapezoidal screw surface and the sub-trapezoidal screw surface are interposed by a spring between the sub-nut which is screwed with the screw portion and spline-coupled to the wheel nut. And the rod can be output in both left and right directions without backlash, so that it is possible to prevent rattle noise and to improve responsiveness. .

According to the fifth aspect of the present invention, a non-rotating plug screwed into a screw hole formed in the gabox is inserted into the non-rotating groove formed in the rod, and the friction of the trapezoidal screw is caused by rotation of the wheel nut. Since the detent is prevented from rotating the rod by force, the detent plug for restricting the detent of the rod can be easily replaced or detached as required.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a rear wheel steering device showing an embodiment of the present invention.

FIG. 2 is a side sectional view of the same.

FIG. 3A is an explanatory diagram for explaining the operation of a backlash removing unit. (B) It is explanatory drawing explaining the effect | action of a backlash removal means similarly. (C) It is explanatory drawing explaining the effect | action of a backlash removal means similarly.

FIG. 4 is a front sectional view of a rear wheel steering device showing another embodiment.

FIG. 5 is an explanatory diagram for explaining the operation of the backlash removing means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Gap box 2a Small inside diameter part 2b Large inside diameter part 2c Screw hole part 3 Bolt 4 Cap 4a Inside diameter part 5 Bush 6 Rod 6b Rod selection part 6c, 6f, 6i Trapezoidal screw part 6d, 6h, 6j Right screw surface 6e , 6g, 6k Left-hand thread surface 6m Non-rotating groove 7 Ring nut 8 Wheel nut 8a Annular convex portion 8b Worm gear 8c Trapezoidal thread portion 8d Right-hand thread surface 8e Left-hand thread surface 9 Bush 10 Bearing 11 Bush 12 Bearing 13 Shaft 14 joint 15 motor 15a shaft 16 case 17 plate 17a notch 18 pin 19 detent means 20 thrust bearing 21 spring receiver 22 shaft 23 spring 24 threaded part 25 backlash removing means 28 bolt 30 control device 31 Hall element 32 Resolver 33 Cover 34 No. cable 35 Power cable 40 Wheel nut 40a Inner diameter portion 40b Annular portion 40f Trapezoidal screw portion 40h Right side screw surface 40g Left side screw surface 41 Sub nut 41a One end side of wheel nut 41b Spline 41i Trapezoidal screw portion 41j Right side screw surface 41k Left thread surface 42a, 42b Threaded portion 43 Spring 44 Worm gear 45 Bearing 46 Bush 47 Non-rotating plug 48 Backlash removing means 49 Non-rotating means

Claims (5)

[Claims] 1. A cap fastened to a gearbox, a rod supported by a support member provided on the gearbox and the cap, slidably fitted therein, and a bearing screwed into a threaded part formed on the rod. A wheel nut supported by members and rotatably mounted; a backlash removing means for elastically pressing and contacting a threaded portion of a rod and a trapezoidal threaded portion of the wheel nut to remove backlash; A detent means provided to engage between the rod and the cap or gearbox for regulation;
A worm shaft supported by a bearing so as to mesh with a worm gear formed in a wheel nut; a motor connected to the worm shaft and fastened to a gearbox to rotate and drive; A rear wheel steering device comprising a detecting means for detecting rotation and a control device for controlling a motor based on the detecting means, wherein the detecting means and the control device for detecting the rotation of the motor are mounted on a motor. A rear wheel steering device, which is integrally mounted in a case of a vehicle. The backlash removing means includes a bearing provided at one end of a wheel nut and a press-fitted and fixed to a rod.
An elastic member is coaxially inserted between the screw and the trapezoidal thread, and the threaded portion of the rod and the trapezoidal thread of the wheel nut is elastically pressed into contact with each other to remove backlash. The rear wheel steering device according to claim 1. 3. The rotation preventing means is characterized in that a pin protruding from a cap is engaged with a notch provided in a plate press-fitted and fixed to the rod, thereby restricting rotation of the rod. The rear wheel steering device according to claim 1. 4. The backlash removing means comprises: a main thread portion and a sub thread portion formed into a rod; a wheel nut screwed into the main thread portion and supported by a bearing member to be freely rotatably mounted; A sub-nut that is screwed into the threaded portion and spline-coupled to the wheel nut, and an elastic member inserted coaxially with the trapezoidal threaded portion between the sub-nut and the inner diameter portion of the wheel nut, and includes a rod and a wheel.
2. The rear wheel steering device according to claim 1, wherein the threaded portion of the trapezoidal thread portion of the run nut and the sub nut is elastically pressed into contact to remove backlash. 5. The rotation preventing means according to claim 1, wherein said rotation preventing means is adapted to insert and engage a rotation preventing plug which is screwed into a threaded portion provided on said gear box into a groove provided on said rod to regulate rotation of said rod. The rear wheel steering device according to claim 1, wherein