JPH0365469A - Rear wheel steering system - Google Patents

Abstract

PURPOSE:To improve reliability and responsiveness for expanding freedom is design by a method wherein a rear wheel controlling valve cylinder and a cylinder of a rear wheel cylinder are connected to each other to be a fixed side while a pair of valve operating cylinders and a piston rod of the rear wheel cylinder are connected to each other to be a movable side. CONSTITUTION:The cylinder of a rear control valve 29 is connected to the cylinder of a rear cylinder 33 to be a fixed side, while the cylinder of a pair of valve operating cylinders 31 is connected to a piston rod 69 of the rear wheel cylinder 33 to be a movable side. Therefore, the weight of a member for moving along with the motion of the piston rod 69 of the rear wheel cylinder 33 decrease to largely reduce the inertial weight. Thus reliability and responsiveness can be improved. In addition, since the cylinder of the rear wheel control valve 29 is on the fixed side, it is not necessary to use a flexible piping as one to be provided between the rear control valve 29 and the rear wheel cylinder 33, thereby expanding freedom in design.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a rear wheel steering device that steers the rear wheels in conjunction with the steering of the front wheels.

(Prior Art) The present applicant has already applied for a rear wheel steering device according to Japanese Patent Application No. 1-61248. This device controls the steering angle of the rear wheels by feeding back the position of the piston rod of the rear wheel cylinder that steers the rear wheels, and FIG. 3 shows the device.

First, let's explain from the front wheel side. A front wheel cylinder 1 is provided, and the front wheel cylinder 1 is composed of a cylinder 3 and a piston 5 that slides inside the cylinder 3.

A rack shaft 7 is connected to the piston 5, and front wheels 9.9 are connected to both ends of the rack shaft 7.

A rack 11 is formed on the rack shaft 7, and a pinion 13 is engaged with the rack 11.

A shaft 14 is fixed to the pinion 13, and a steering handle 15 is attached to the shaft 14.

A steering angle sensor 17 is inserted into the shaft 14, and a detection signal s17 from the steering angle sensor 17 is input manually to the controller 19. A signal s20 from the vehicle speed sensor 20 is also input to the controller 19.

Further, a switching valve 16 is attached to the shaft 14 at the secondary side position of the steering angle sensor 17.

For example, assume that the steering handle 15 is rotated clockwise in the figure (in the direction of arrow a). At this time, the shaft 14 swings, and the switching valve 16 switches due to the swing. By switching the switching valve 16, the hydraulic pump (not shown) is connected to the chamber on the right side of the cylinder 3, and at the same time, the tank and the chamber on the left side are connected.

As a result, the piston 5 and rack shaft 7 move to the left in the figure, steering the front wheels 9.9 clockwise (in the direction indicated by the arrow). At this time, the steering handle 15 is also rotated in the same direction via the rack 11 and pinion 13.

A front wheel steering detection cylinder 21 is arranged adjacent to the front wheel cylinder 1, and the rear wheels are steered via this front wheel steering detection cylinder 21.

The front wheel steering detection cylinder 21 includes a cylinder 23 and a piston 25 slidably housed in the cylinder 23.
It consists of

An actuation rod 27 is connected to the piston 25, and the rack shaft 7 is connected to the piston 25 via the actuation rod 27.
is connected to. That is, the piston 25 slides in synchronization with the movement of the rack shaft 7.

Further, ports 24.26 are formed in the cylinder 23, and the cylinder 23 is connected to a valve operation cylinder side, which will be described later, via the ports 24.26.

The device for steering the rear wheels includes a rear wheel control valve 29 and a pair of valve operation cylinders 3 disposed on both sides of the rear wheel control valve 29.
1.31 and a rear wheel cylinder 33.

The rear width control valve 29 has a cylinder 35 and a cylinder 35.
a spool 37 slidably housed within the spool 3;
7 in a neutral position. Solenoids 41, 41 are arranged at both ends of the spool 37. Also, Bush Rod 3
9.39 are disposed through the solenoid 41.41 and abut against both ends of the spool 37.

Both solenoids 41 are connected to the controller 19 described above.
selectively excited by

Ports 43 and 45 are formed in the cylinder 35, and a hydraulic pump 47 is connected to the boat 43, while a tank 49 is connected to the port 45.

Another port 51, 53 is formed in the cylinder 35, and these ports 51, 53 are connected to the rear wheel cylinder 33 side.

The valve operating cylinder 31 is composed of a cylinder 55, a piston 57 that slides within the cylinder 55, and a spring 59. A piston rod 61 is formed in the piston 57 .

A clearance angle is provided between the piston rod 61 and the bushing rod 39.

Further, a port 58 is formed in the cylinder 55,
A piping 60 is provided between this port 58 and the port 24.
is installed.

The valve operating cylinder 31 on the opposite side has a similar configuration, and a pipe 64 is disposed between a port 62 formed in the cylinder 55 and the port 26.

The rear wheel cylinder 33 has a cylinder 63 and this cylinder 6.
3 and a spring 67.

A piston rod 69 is connected to the piston 65, and a rear wheel 71 is connected to both ends of the piston rod 69.
．． 71 are connected.

The cylinder 35 of the rear wheel control valve 29 is connected to the piston rod 6.
9 (movable side). Further, the cylinders 55, 55 of the pair of valve operating cylinders 31, 31 are connected to the cylinder 63 (fixed side).

Further, boats 73 and 75 are formed in the cylinder 33, and are connected to boats 51 and 53 formed in the cylinder 35 of the rear width control valve 29 via pipes 76 and 78, respectively.

The operation will be explained based on the above configuration.

First, a case in a high-speed small steering angle control region, such as when driving on a highway, will be described. When the front wheels 9.9 are steered clockwise in the figure, the front wheel steering detection cylinder 21 and the piping 6
0, pressure oil is supplied to the valve operating cylinder 31 on the left side in the figure.

As a result, the piston 57 of the valve operating cylinder 31 moves to the right in the figure. However, since the rudder angle is small,
Since the amount of movement of the piston 57 is smaller than the gap 2, it has no effect on the rear wheel control valve 29, and as a result, the rear wheels 71, 71 are not steered.

In this way, in the high-speed small steering angle control range, no steering is performed by the valve operation cylinders 31, 31, and the controller 1
9 is used for steering.

That is, the vehicle speed is detected by the vehicle speed sensor 20 and inputted to the controller 19 as a detection signal s20. at the same time,
The steering direction and steering angle are detected by the steering angle sensor 17 and are manually input to the controller 19 as a detection signal s17.

Based on the rain detection signals s20 and s17, the controller 19 controls one of the solenoids 41 so that the rear wheels 71.71 are steered in the same phase mode as the front wheels 9.9 or in the instantaneous out-of-phase and then in-phase mode. It is excited by outputting the signal s19 or s19.

Next, a case in the low speed large steering angle control region will be explained. In this case, since the amount of movement of the piston 57 is greater than the gap angle, the piston rod 61 moves the spool 37 to the right in the figure via the bush rod 39.

By this movement of the spool 37, the switching operation of the rear wheel control valve 29 is performed, and the hydraulic pump 4 is supplied to the left side chamber of the cylinder 63 of the rear wheel cylinder 33 via the boat 53.75.
Pressure oil is supplied from 7. Also, the pressure oil from the chamber on the right side in the figure of the cylinder 63 is transferred to the tank 4 via the boat 51.73.
Returned to 9.

As a result, the piston 65 and piston rod 69 move to the right in the figure, and the rear wheels 71 and 71 move counterclockwise in the figure (
The vehicle is steered in the direction of arrow C).

Further, due to the movement of the piston rod 69, the cylinder 35 of the rear wheel control valve 29 also moves in the same direction as the spool 37. As a result, the rear wheel control valve 29 becomes in a neutral state, and the piston rod 69 of the rear wheel cylinder 33 also stops. This completes the steering of the rear wheels.

In other words, the piston rod 69 of the rear wheel cylinder 33 moves by an amount corresponding to the amount of pressure oil supplied from the front wheel steering detection cylinder 21 to the valve operation cylinder 31, that is, the amount of steering of the front wheel 9.9. , so-called position feedback control is performed.

(Problems to be solved by the present invention) The conventional configuration described above has the following problems.

As already mentioned, the cylinder 35 of the rear wheel control valve 29 is connected to the piston rod 69 (movable side), and the cylinder 55.5 of the pair of valve operating cylinders 31.31 is connected to the piston rod 69 (movable side).
5 is connected to the cylinder 63 (fixed side).

In other words, since the cylinder 35 of the rear wheel control valve 29, which is relatively heavy, is configured to move as the piston rod 69 moves, the inertial weight becomes large, resulting in poor reliability and responsiveness. There was a problem with this.

Also, since the cylinder 35 of the rear wheel control valve 29 moves,
As the pipes 76 and 78 disposed between the rear wheel cylinder 33 and the rear wheel cylinder 33, flexible pipes must be used, and there is also a problem in that the degree of freedom in design is narrowed.

The present invention has been made based on the above points, and an object thereof is to reduce the inertial weight by making the member that moves with the movement of the piston rod of the rear wheel cylinder relatively small in weight. To provide a rear wheel steering device capable of improving reliability and responsiveness by reducing noise, and increasing the degree of freedom in designing piping arranged between a rear wheel control valve and a rear wheel cylinder. It is in.

(Means for Solving the Problems) In order to achieve the above object, a rear wheel steering device according to the present invention includes a cylinder and a spool slidably housed in the cylinder, and the sliding of the spool allows a flow path to be made. a rear wheel control valve that switches the flow of pressure oil to circulate the pressure oil; and the rear wheel control valve is arranged on both sides of the spool in the sliding direction, and consists of a cylinder and a piston slidably housed in the cylinder. , a pair of valve operation cylinders that switch the rear wheel control valve by sliding the piston using pressure oil from the front wheel steering detection cylinder and pressing the spool; It consists of a piston housed in the piston, and a piston rod that is integrally attached to the piston and has rear wheels attached to both ends.The piston is moved by pressure oil supplied from the rear wheel control valve, and the piston rod and a rear wheel cylinder that steers the rear wheels via the rear wheel cylinder, the cylinder of the rear wheel control valve and the cylinder of the rear wheel cylinder are connected to form a fixed side, and the cylinder of the pair of valve operation cylinders and the rear wheel are connected to each other. It is characterized in that it is connected to the piston rod of the cylinder to form the movable side.

(Operation of the present invention) The cylinder of the rear wheel control valve is connected to the cylinder of the rear wheel cylinder (fixed side), and the cylinder of the pair of valve operation cylinders is connected to the piston rod of the rear wheel cylinder (
Movable side).

Therefore, the weight of the member that moves with the movement of the piston rod of the rear wheel cylinder is reduced, and the inertial weight is significantly reduced.

Therefore, reliability and responsiveness are improved.

In addition, since the cylinder of the rear wheel control valve is fixed, there is no need to use flexible piping between the rear wheel control valve and the rear wheel cylinder, increasing the degree of freedom in design. can do.

(Embodiment of the present invention) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Incidentally, the same parts as in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, the cylinder 35 of the rear wheel control valve 29 is connected to the cylinder 63 of the rear wheel cylinder 33 (fixed side), and the cylinder 55 of the valve operating cylinder 31.31 is connected to the piston rod 69 of the rear wheel cylinder 33. is concatenated to (
Movable side).

In addition, in the piping connection structure between the rear wheel cylinder 33 and the control cylinder 35, the boat 53 and the boat 73 are connected, and the port 5
1 and a boat 75 are connected, which is opposite to the case of the conventional example.

The operation will be explained based on the above configuration.

In the high-speed small steering angle control range, the controller 19 performs steering as described above.

Next, a case in the low speed large steering angle control region will be explained. In this case, since the amount of movement of the piston 57 is greater than the gap angle, the piston rod 61 moves the spool 37 to the right in the figure via the bush rod 39.

By this movement of the spool 37, the rear wheel control valve 29 is switched, and the hydraulic pump 4 is connected to the right side chamber of the cylinder 63 of the rear wheel cylinder 33 through the port 53.73.
Pressure oil is supplied from 7. Also, the pressure oil from the chamber on the left side in the figure of the cylinder 63 flows through the port 75.51 to the tank 4.
Returned to 9.

As a result, the piston 65 and piston rod 69 move to the left in the figure, and the rear wheels 71 and 71 move counterclockwise in the figure (
The vehicle is steered in the direction of arrow C).

Due to the movement of the piston rod 69, the valve operating cylinder 31.31 also moves to the left in the figure. At this time, the valve operation cylinder 31 at the input end moves as it is without changing the relative position of the piston 57 with respect to the cylinder 55. Then, the force of the rear width control valve 29 on the spool 37 is released, so the spool 37 returns to the neutral position. Therefore, rear wheel steering is completed.

According to this embodiment, the following effects can be achieved.

First, the inertial weight is reduced, which improves reliability and responsiveness. This allows the cylinder 55 of the valve operation cylinder 31, 31, which is a relatively light weight object, to be replaced with the cylinder 55 of the rear wheel cylinder 33.
This is because the piston rod 69 is connected to the movable side.

Furthermore, since the cylinder 35 of the rear wheel control valve 29 is fixed and does not move, the pipes 76 and 78 disposed between the rear wheel control valve 29 and the rear wheel cylinder 33 can be flexible. There is no need to use a steel pipe, and the degree of freedom in design can be expanded, such as by allowing the use of general steel pipes.

(Effects of the present invention) As detailed above, according to the rear wheel steering device according to the present invention, the cylinder of the rear wheel control valve, which is a relatively heavy object, is fixed, and the cylinder of the valve operation cylinder, which is a relatively light weight object, is fixed. By making the cylinder movable, it is possible to reduce the inertial weight, thereby improving reliability and responsiveness. The degree of freedom in design can be expanded, such as by making it possible to use internal steel pipes.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams showing one embodiment of the present invention.
FIG. 2 is a cross-sectional view of the rear wheel steering device in a neutral state, and FIG. 3 is a configuration diagram of a conventional rear wheel steering device. 21--front wheel steering detection cylinder, 29--rear wheel control valve, 31-valve operation cylinder, 33--rear wheel cylinder, 35-
...Cylinder, 37--Spool, 55--Cylinder,
57--piston, 63--cylinder, 65--piston, 69--piston rod, 71--rear width.

Claims (1)

[Scope of Claims] A rear wheel control valve comprising a cylinder and a spool slidably housed in the cylinder, and which switches a flow path by sliding the spool to circulate pressure oil; They are arranged on both sides of the valve spool in the sliding direction, and consist of a cylinder and a piston slidably housed in the cylinder, and the piston is slid by pressure oil from the front wheel steering detection cylinder. A pair of valve operation cylinders that switch and operate a rear wheel control valve by pressing and energizing a spool; a cylinder, a piston slidably housed in the cylinder; a piston rod to which a wheel is attached, and a rear wheel cylinder that slides the piston using pressure oil supplied from the rear wheel control valve and steers the rear wheel via the piston rod; The cylinder of the wheel control valve and the cylinder of the rear wheel cylinder are connected to form a fixed side, and the cylinder of the pair of valve operation cylinders and the piston rod of the rear wheel cylinder are connected to form a movable side. Rear wheel steering device.