JPH0558564U - Rear wheel steering system - Google Patents

Abstract

(57) [Abstract] [Purpose] In a rear wheel steering system using a servomotor, the structure of an operating device for limiting the maximum value of the rear wheel steering angle at high speed to a small value is simplified and a special operation is performed. No need for power. A rotation stopper 30 is fixed to a rotating member 11 which is rotated by a servomotor 22 to axially move an operating rod 12 to steer a rear wheel, and at a medium and high speed, a locking device 40 of a locking device 40 is provided in a fan-shaped notch 30a of the rotation stopper. Stopper rod 40a
To project. A piston 52 that moves according to wind pressure is provided in a cylinder portion 51a that is formed in a casing 51 that is fixed to the vehicle body and that is open to the front side in the traveling direction of the vehicle.
The stopper rod is projected into the fan-shaped notch 30a at the time of traveling at medium and high speeds by connecting to 0a. The stroke transmission means may be an operation cable or a hydraulic pipe.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a rear wheel steering device in which a rear wheel is steered by a servomotor that operates according to a traveling state such as a front wheel steering angle and a vehicle speed.

[0002]

[Prior Art]

 In this type of rear wheel steering system, a ball nut, which is rotatably supported in the housing, engages the middle part of the operating rod with a screw, and a servomotor that operates according to the running state moves the ball through the worm wheel and the worm. There is one in which the nut is rotated to axially move the operating rod, and the rear wheels are steered via tie rods provided at both ends of the operating rod. The rear wheel rudder angle is smaller than the front wheel rudder angle, but is relatively large in reverse phase at low speed (for example, up to 5 degrees), 0 at medium speed, and relatively small in phase at high speed (for example, maximum). However, it is not preferable that large steering is performed at medium and high speeds. Therefore, in the above-mentioned conventional technology, a rotation stopper with a fan-shaped notch is fixed to the ball nut, and when the vehicle speed detected by the vehicle speed sensor is medium to high speed, an electromagnetically or hydraulically operated stopper rod attached to the housing is used. Even if the servomotor or the controller that controls it is operated abnormally, the maximum value of the rear wheel steering angle is within the above-mentioned relatively small value even when the servomotor or the controller controlling this is operated by the electronic control unit so that it protrudes so as to engage with the fan-shaped notch. Are regulated so that In the case of using a hydraulically actuated stopper rod, it is conceivable that the stopper rod is actuated by utilizing the gear generation pressure of the front wheel power steering device which increases as the vehicle speed increases.

[0003]

[Problems to be solved by the device]

 However, in the above-mentioned conventional technique, since the vehicle speed sensor and the electronic control device are used, the number of parts is increased, and wiring and piping are required, which causes a problem that the structure is complicated and the cost is high. The one that uses the pressure generated by the gears of the front wheel power steering device requires a long pipe, which requires time and effort to mount it on the vehicle body and is also expensive. In addition, all of them require power to operate, resulting in energy loss. An object of the present invention is to solve the above problems and to obtain a rear wheel steering system having a simple structure and requiring no special power for operating the stopper rod.

[0004]

[Means for Solving the Problems]

 To this end, the rear wheel steering system according to the present invention, as illustrated in FIGS. 1 to 5, includes a rotating member 11 rotatably supported by a housing 10 and the housing 10 coaxially with the rotating member 11. And an operating rod 12 that is supported by the same and is screwed to the rotating member to steer the rear wheels by axial movement, and the rotating member 11 from the neutral position to both directions depending on the traveling state such as the front wheel steering angle. A rotating servo motor 22; a rotation stopper 30 coaxially fixed to the rotating member 11 and having a fan-shaped notch 30a formed on the outer peripheral portion; and a protrusion provided in the housing 10 and protruding into the fan-shaped notch 30a in a high-speed running state. A rear wheel steering system including a locking device 40 having a stopper rod 40a that regulates the rear wheel steering angle within a small range and retreats in a low speed traveling state to release this regulation. Is a casing 51 having a cylinder portion 51a that is open at a position where it receives wind pressure due to traveling of the vehicle, and is slidably supported in the cylinder portion 51a, and is positioned at the one end portion side at low speed traveling and at high speed traveling. An operating device 50 including a piston 52 that moves to the opposite side by the wind pressure is provided, and the movement of the piston 52 due to the wind pressure is transmitted to the stopper rod 40a so that the stopper rod 40a is placed in the fan-shaped notch 30a during high speed traveling. It is characterized in that it is provided with a stroke transmission means 60 for causing it to project.

[0005]

[Action]

 In a low speed traveling state in which the wind pressure applied to the one end side of the cylinder portion 51a of the actuator 50 is small, the piston 52 is located on this one end side, and the stopper rod 40a of the locking device 40 is retracted from the fan-shaped notch 30a. Since the rotation of the rotating member 11 is not limited, the rear wheel can be steered largely. In a high-speed running state, the wind pressure applied to one end of the cylinder portion 51a increases, and this wind pressure causes the piston 52 to move to the opposite side, and the stroke transmission means 60 transmits this movement to the stopper rod 40a to cause the fan-shaped notch 30a to move. To project. Therefore, in this state, even if the operation of the servo motor 22 or the controller that controls the servo motor 22 is abnormal, the maximum value of the rear wheel steering angle is regulated so as not to exceed the relatively small value allowed by the fan-shaped notch 30a. It

[0006]

[Effect of the device]

 As described above, according to the present invention, the operating device for activating the stopper rod that projects into the fan-shaped notch and limits the maximum value of the rear wheel steering angle at high speed is composed of a casing and a piston, so that the structure is simple. However, since this operating device may be located at a position where one end of the cylinder part receives the wind pressure due to the traveling of the vehicle, the arrangement is relatively free and the stroke transmission means is short, and therefore the structure of the rear wheel steering device is sufficient. It can be simplified and the manufacturing and assembly costs can be reduced. In addition, the stopper rod does not require any special power because it operates by the wind pressure applied to the piston as the vehicle travels.

[0007]

【Example】

 First, the first embodiment shown in FIGS. 1 to 3 will be described. As shown in FIGS. 1 and 2, a ball nut (rotating member) 11 is rotatably supported by a bearing 24 in a housing 10 of the rear wheel steering device. The ball nut 11 is coaxial with the ball nut 11. A threaded portion 12a at the center of the operating rod 12 supported by the housing 10 so as to be movable in the direction and prevented from rotating is threadedly engaged with a ball nut 11 via a ball 13. A compressed neutral return spring 15 is interposed between a pair of spring receivers 16 that are slidably provided on a part of the operating rod 12 by a clip 19 so that the outward movement is restricted. In this state, the outer surface of the flange portion of each spring receiver 16 is in contact with the inner end surface of the housing 10. Both ends of the operating rod 12 are connected to a knuckle arm (neither shown) that supports the left and right rear wheels via a ball joint 17 and a tie rod 18. On the left side of the ball nut 11 in FIG. 1, a differential transformer 14 for detecting the rear wheel steering angle by the movement of the operating rod 12 is provided.

As shown in FIGS. 1 and 2, a servo motor 22 having an axis line that three-dimensionally intersects with the operating rod 12 is provided in the housing 10, and the worm 21 key-connected to the output shaft 22a of the servo motor 22 is It meshes with a worm wheel 20 coaxially fixed to the ball nut 11 via a key 23. The servomotor 22 is actuated by a controller (not shown) according to the running condition such as the front wheel steering angle and the vehicle speed, whereby the ball nut 11 is rotated and the actuating rod 12 is axially moved to steer the left and right rear wheels. ..

As shown in FIGS. 1 and 2, a rotation stopper 30 is coaxially fixed to one side of the worm wheel 20 fixed to the ball nut 11 via a common key 23. A fan-shaped notch 30a is formed on the outer peripheral portion of the. The housing 10 is provided with a locking device 40 at an axial position corresponding to the rotation stopper 30. The locking device 40 is provided with a cylinder member 41 fixed to the housing 10 with a screw and having an axis line orthogonal to the actuating rod 12. The movable member 42 slidably supported on the inner peripheral surface of the locking member 40 is a fan-shaped notch 30a. It is biased by a return spring 43 in a direction to retreat from it, and a stopper rod 40a which can be engaged with the fan-shaped notch 30a by the movement against the return spring 43 is coaxially integrally formed. The locking device 40 is actuated by the actuating device 50 described below via the stroke transmitting means 60. The stroke transmission means 60 of the first embodiment is a flexible operation cable. One end of the outer cable 61 of the operation cable is fixed to the cap 41a fixed to the outer end of the cylinder member 41, and one end of the inner wire 62 is fixed. The cylindrical tip member 62a formed in the above is engaged in the locking hole 42a formed in the rear portion of the moving member 42.

Next, referring to FIG. 3, an operating device 50 for operating the locking device 40 via the operating cable 60 will be described. A casing 51 is attached to a vehicle body of an automobile via a bracket 54, and a cylinder portion 51a is formed in the opening on one end side of the cylinder portion 51a. The funnel portion 51b is opened on the front side in the traveling direction of the vehicle in a state of being attached to the vehicle body, that is, on the side receiving the wind pressure accompanying the traveling of the vehicle. A piston 52 is axially movably fitted to the cylinder portion 51a, and its stroke is restricted by two snap rings 53 provided on the cylinder portion 51a.

A cylindrical protruding portion 51c is coaxially formed on the bottom of the casing 51 on the side opposite to the funnel portion 51b, and the outer tube 61 of the operation cable 60 is attached to the cap 57 fixed to the tip thereof. The other end of is fixed. A protrusion 56 protruding toward the cap 57 side is coaxially formed integrally with the piston 52, and a tip end member 62b formed at the other end of the inner wire 62 is engaged with a locking hole 56a formed at the tip end portion thereof. .. A plurality of air escape holes 51d are provided at the bottom of the casing 51. Most of the inner wire 62 is flexible, but since both ends projecting from the outer tube 61 are rods having bending rigidity, both pushing and pulling forces can be transmitted. As a result, the stopper rod 40a and the piston 52 are interlocked with each other and always move by the same amount.

Next, the operation of the first embodiment will be described. When inoperative, the moving member 42 is biased by the return spring 43 to the position where the stopper rod 40a is retracted from the fan-shaped notch 30a, and the piston 52 is also biased by the return spring 43 via the operation cable 60, as shown in FIG. Thus, it is located on the funnel portion 51b side. When the vehicle travels at a low speed, the return spring 43 does not bend because the wind pressure applied to the piston 52 is small as the vehicle travels, and the stopper rod 40a and the piston 52 are in the same positions as when they were inoperative. That is, since the stopper rod 50a is retracted from the fan-shaped notch 30a of the rotation stopper 30 and the rotation of the rotating member 11 is not restricted, the rear wheel can be steered largely in reverse phase (for example, 5 degrees each on the left and right sides).

During medium- and high-speed traveling, since the wind pressure applied to the piston 52 increases, the piston 52 and the moving member 42 move against the return spring 43, and the stopper rod 40a moves along the alternate long and two short dashes line A in FIG. 1 and FIG. As shown in FIG. 3, the rotation stopper 30 projects into the fan-shaped notch 30a. Therefore, in this state, even if the operation of the servomotor 22 or the controller controlling the servomotor 22 is abnormal, the maximum value of the rear wheel steering angle is a relatively small value allowed by the fan-shaped notch 30a (for example, 1 degree for each of left and right). It is regulated not to exceed the above.

According to the first embodiment described above, the operating device 50 that operates the stopper rod 40a in accordance with the traveling speed is mainly composed of the casing 51 and the piston 52, and the operating device 50 includes the cylinder portion 51a. Since the funnel portion 51b at one end may be located at the front side in the traveling direction of the vehicle, the arrangement is relatively free and the operation cable 60 is comparatively short. Therefore, the structure of the rear wheel steering device is simplified, and the manufacturing and Assembly costs can be reduced. Further, since the stopper rod 40a is actuated by the wind pressure applied to the piston 52 as it travels, no special power is required.

Next, a second embodiment shown in FIGS. 4 and 5 will be described. The second embodiment is different from the first embodiment only in the structures of the locking device 40, the actuating device 50, and the stroke transmitting means 60, and therefore the differences will be mainly described.

As shown in FIG. 4, the housing 10 is provided with a hydraulic locking device 40 having a stopper rod 40a at the same axial position as in the first embodiment. This locking device 40 is fixed to the housing 10 and has a cylinder 45 having an oil seal 47 and a support ring 47a, a hydraulic piston 46 fitted to the oil seal 47 and having a stopper rod 40a integrally formed at the tip thereof, and a stopper rod 40a. Is constituted by a return spring 43 that urges the hydraulic piston 46 in a direction to retract from the fan-shaped notch 30a and contacts the stopper member 45b of the cylinder 45. To the port 45a of the cylinder 45, one end of a hydraulic pipe 65 that constitutes the stroke transmission means 60 is liquid-tightly connected, and the hydraulic pressure from the actuator 50 shown in FIG. 5 is applied.

In the configuration of the actuator 50 of the second embodiment shown in FIG. 5, the casing 51, the piston 52, the snap ring 53, and the bracket 54 except for the protrusion 51c are the same as those of the first embodiment shown in FIG. Is. A plunger 58, which is integrally formed by coaxially protruding from the piston 52, is liquid-tightly fitted into the plunger hole 51 formed coaxially with the projecting portion 51c via a seal ring 58a. The other end of the hydraulic pipe 65 is screwed into the tip of the protruding portion 51c in a liquid-tight manner and fixed by a lock nut 59. The cylinder 45, the plunger hole 51, and the hydraulic pipe 65 which are in communication with each other operate inside. It is filled with oil. As a result, the stopper rod 40a moves with respect to the piston 52 by an amount corresponding to the sectional area ratio of the plunger 58 and the hydraulic piston 46.

Next, the operation of the second embodiment will be described. Similar to the first embodiment, when not operating, the hydraulic piston 46 is located at the position where the stopper rod 40a is retracted from the sectoral notch 30a, and the piston 52 is located at the funnel portion 51b side. When the vehicle is traveling at a low speed, the return spring 43 does not bend, the stopper rod 40a and the piston 52 are in the same positions as when they are not operating, and the stopper rod 40a retracts from the fan-shaped notch 30a and the rotation of the rotating member 11 is not restricted. Therefore, the rear wheels can be largely steered in the reverse phase.

During middle- and high-speed traveling, the piston 52 and the hydraulic piston 46 move against the return spring 43, and like the first embodiment, the stopper rod 40a has a fan-shaped notch 30a as shown by a chain double-dashed line A in FIG. Project inside. Therefore, in this state, even if the operation of the servo motor 22 or the controller that controls the servo motor 22 is abnormal, the maximum value of the rear wheel steering angle is regulated so as not to exceed a relatively small value allowed by the fan-shaped notch 30a. To be done.

Also in the second embodiment, as in the first embodiment, the structure of the rear wheel steering device is simplified, the manufacturing and assembling costs can be reduced, and special power is required to operate the stopper rod. Not. According to the second embodiment, the operating force of the stopper rod 40a can be increased according to the cross-sectional area ratio of the plunger 58 and the hydraulic piston 46, and the diameter of the operating device 50 can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main body of a first embodiment of a rear wheel steering device according to the present invention.

2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a longitudinal sectional view of an operating device of a first embodiment of a rear wheel steering device according to the present invention.

FIG. 4 is a vertical cross-sectional view of a body portion of a second embodiment of a rear wheel steering device according to the present invention.

FIG. 5 is a longitudinal sectional view of an operating device of a second embodiment of a rear wheel steering device according to the present invention.

[Explanation of symbols]

10 ... Housing, 11 ... Rotating member (ball nut),
12 ... Operating rod, 22 ... Servo motor, 30 ... Rotation stopper, 30a ... Fan-shaped notch, 40 ... Locking device, 40a ...
Stopper rod, 50 ... Actuating device, 51 ... Casing,
51a ... Cylinder part, 52 ... Piston, 60 ... Stroke transmission means (operation cable, hydraulic pipe).

Claims (1)

[Scope of utility model registration request] 1. A rotating member rotatably supported by a housing, and an operating rod which is coaxially supported by the housing and is screw-engaged with the rotating member to steer the rear wheel by axial movement. A servomotor that rotates the rotating member in both directions from its neutral position in accordance with a traveling state such as a front wheel steering angle; a rotation stopper that is fixed coaxially to the rotating member and has a fan-shaped cutout on its outer peripheral portion; The locking device is provided in the housing and has a stopper rod that projects into the fan-shaped notch in a high-speed traveling state to regulate the rear wheel steering angle within a small range and retracts in a low-speed traveling state to release the regulation. In a rear wheel steering device, a casing having a cylinder portion that opens at a position where one end receives a wind pressure due to traveling of a vehicle, and a low speed that is slidably supported in the cylinder portion. The stopper rod is provided at the one end side when traveling and is moved to the opposite side by the wind pressure when traveling at high speed. Further, the movement of the piston due to the wind pressure is transmitted to the stopper rod, and the stopper rod is traveling at high speed. A rear-wheel steering system comprising: a stroke transmission means for projecting a fan into the fan-shaped notch.