JPH0140783Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Technical field) The present invention relates to a rear wheel steering device for an automobile.

(Prior art) Because front-wheel drive vehicles have a drive mechanism such as a constant velocity joint installed on the front axle, it is not possible to use a large steering angle for the front wheels; When the driver needs to operate the vehicle, for example, when parking the vehicle in the garage, there is an inconvenience in that the driver has to repeatedly operate the steering wheel.

Therefore, it has been proposed to steer the rear wheels in conjunction with the steering of the front wheels, thereby reducing the steering load on the front wheels.

An example of a rear wheel steering device will now be described with reference to FIG.

In FIG. 1, reference numeral 1 indicates a hydraulic cylinder for rear wheel steering, reference numeral 2 indicates a piston rod return device, and reference numeral 3 indicates a piston rod.

The rear wheel steering hydraulic cylinder 1 has a space divided into left and right by a partition wall 100 formed in the middle, one of which is used as a part of a parallel link of a rear wheel steering mechanism (not shown). A piston chamber 101 in which a piston 3a of a piston rod 3 is supported for reciprocating movement, and the other side is a return device 2 for the piston rod.

The piston chamber 101 is partitioned into two chambers f and g by an internal piston 3a, and an output side oil passage of a control valve described later is connected to each chamber.

On the other hand, the piston rod return device 2 includes a large diameter portion 3b of the piston rod 3 fitted in the other space 102 of the hydraulic cylinder 3, and a locking piece 4 that is removably engaged with a groove portion 3c formed in the large diameter portion 3b. and sliding rings 5, 6 that are slidably supported on the piston rod 3 on both sides of the large diameter portion 3b.

Then, in the other space 102 of the hydraulic cylinder 1, the outer side of the sliding rings 5 and 6, that is, the space 10
An output side oil passage of a control valve, which will be described later, is connected to the vicinity of both ends of 2.

The locking piece 4 is housed in a cylindrical body 103 formed on the outer wall surface of the rear wheel steering hydraulic cylinder 1, and is engaged with the groove 3c of the piston rod 3 by a spring 7 installed in the cylindrical body 103. A bias is given in the direction of

Inside this cylindrical body 103, there is an oil passage forming a hydraulic circuit for applying a biasing force in a direction (downward in the figure) to remove the locking piece 4 from the groove 3c of the piston rod 3 against the elasticity of the spring. It is connected.

The groove 3c of the piston rod 3 is placed in a position where it can engage with the locking piece 4 during normal operation, that is, when the rear wheels are not being steered. The position of the piston rod 3 in this state is set as a neutral position.

When the piston rod 3 is in the neutral position, the inner wall surface of the hydraulic cylinder 1 facing the large diameter portion 3b of the piston rod 3 is formed to protrude somewhat inward, and this locks the movement of the sliding rings 5 and 6. It has become a department.

Reciprocating movement of piston rod 3 and locking piece 4
The control valve 8 is connected to the first and second electromagnetic switching valves 9, 10 and the output side oil passages 11, 12 of the second electromagnetic switching valve 10, respectively. 2 check valves 13, 14, each electromagnetic switching valve 9,
The switching operation of the switch 10 is controlled by a front wheel steering sensor of a steering wheel (not shown) and a control device operated by an output signal from this sensor.

P on the input side of the first and second electromagnetic switching valves 9 and 10
A high pressure oil line 16 connected to a pressure source is connected to the port.
A low pressure oil passage 18 connected to a reservoir 17 is connected to each R port.

On the other hand, one oil passage 19 of the output oil passages of the first electromagnetic switching valve 9 is connected to the other space 102 of the hydraulic cylinder 1 in a branched state, and the other oil passage 20
is connected to the cylindrical body 103.

And the output side oil passage 11 of the second electromagnetic switching valve 10,
12 are piston chambers 10 of the hydraulic cylinder 1, respectively.
Connected to 1.

Further, between the first and second check valves 13 and 14, oil is provided to open the check valve in order to use the other oil path as a return path when high-pressure oil is sent into one oil path. The output oil passages 11 and 12 of the second electromagnetic switching valve 10 and the output oil passage 19 of the first electromagnetic switching valve 9 are connected with throttle valves 23 and 24 for speed adjustment. , 25 are respectively provided. Further, an oil passage 26 is connected between the oil passage 19 and the check valves 13 and 14 for opening the check valves 13 and 14 when high-pressure oil is sent into the oil passage 19.

In the above configuration, when rear wheel steering is performed, when the first and second electromagnetic switching valves 9 and 10 are changed in the direction shown by the arrow d, the output side oil passage 20 of the first electromagnetic switching valve 9 is under high pressure. By communicating with the oil passage 16, the locking piece 4 is removed from the groove 3c of the piston rod 3, and the output side oil passage 19 is connected to the low pressure oil passage 1.
8, the sliding rings 5 and 6 within the hydraulic cylinder 1 can be slid.

On the other hand, the output side oil passage 12 and the high pressure oil passage 16 of the second electromagnetic switching valve 10 communicate with each other, and the pressure in the g chamber in the piston chamber 101 is increased, and the output side oil passage 1
1 and the low pressure oil passage 18 communicate with each other to form the piston chamber 101.
As the pressure in chamber f within the vehicle decreases, the piston 3a of the piston rod 3 moves in the direction shown by arrow c, thereby steering the rear wheels.

Then, when returning the rear wheels to the neutral position,
By setting the conversion directions of the first and second electromagnetic switching valves 9 and 10 to be opposite, the relationship between the oil passages is reversed, and this becomes possible.

By the way, in the above-mentioned rear wheel steering device, the hydraulic cylinder for rear wheel steering is equipped with a piston chamber for rear wheel steering and a return device for the piston rod, so the machining of the hydraulic cylinder becomes complicated. Moreover, the hydraulic cylinder itself becomes large, and the cost including assembly and installation increases.

(Objective) The present invention has been made in view of the above, and its object is to provide a rear wheel steering device for an automobile that can eliminate the above-mentioned drawbacks.

(Configuration) The present invention provides a hydraulic cylinder for rear wheel steering.
This device not only has the function of a piston rod return device, but also simplifies the structure for setting the piston at an intermediate position within the cylinder and setting the piston for steering movement.

The present invention will be explained below with reference to the illustrated embodiments.

Note that the same members in FIG. 2 as in FIG. 1 are given the same reference numerals.

In FIG. 2, a rear wheel steering hydraulic cylinder 50
is formed in a hollow shape, and its interior space serves as a one-chamber piston chamber 51.

The piston chamber 51 accommodates a piston rod 60 that becomes part of a parallel ring (not shown) of the rear wheel steering mechanism.
A piston 61 is fitted and supported so as to be able to reciprocate, and the piston 61 divides the chamber into two chambers f and g. Each of these chambers f and g has an output side oil passage 1 from the second electromagnetic switching valve 10 of the control valve 8.
1 and 12 are connected.

The piston rod 60 is set to a neutral position in which the piston 61 is located in the center of the piston chamber 51 in the longitudinal direction.

A pair of locking pieces 70 are provided on both sides of the piston 61 in the neutral position of the piston rod 60, with a distance corresponding to the length of the piston 50 in the longitudinal direction.

This locking piece 70 is housed in a cylindrical body 52 disposed on the outer wall of the hydraulic cylinder 50 at intervals corresponding to the longitudinal length of the piston 61, and a spring 80 mounted in the cylindrical body 52 Accordingly, the direction in which the piston moves into the piston chamber 51 is given.

Inside this cylindrical body 52, an oil passage 91 for biasing the locking piece 70 in a direction to retreat from the piston chamber 51 against the elasticity of the spring 80 is connected to an electromagnetic switching valve to be described later. . Therefore, the locking piece 70
is capable of protruding into and retracting into the piston chamber 51, and when it protrudes into the piston chamber 51, it interferes with both ends of the piston 61, locking the piston 61 in an intermediate position, and The reciprocating movement of the piston 61 is allowed by being submerged, in other words, removed from the chamber 51.

On the other hand, the control valve 8 includes a spring offset type electromagnetic switching valve 92 instead of the first electromagnetic switching valve 9 shown in FIG. 1, and a first electromagnetic switching valve similar to that shown in FIG. The switching valve 10 and the first electromagnetic switching valve 10
The first and second oil passages interposed in the output side oil passages 11 and 12 of
It is composed of check valves 13 and 14.

A low pressure oil passage 18 is connected to the R port of the electromagnetic switching valve 92.
However, high pressure oil passages 16 are connected to the P ports, respectively.

In the rear wheel steering device having the above configuration,
When steering the rear wheels, if the spring offset type electromagnetic switching valve 92 is moved from the neutral position in FIG. The output side oil passage 91 of the valve 92 and the high pressure oil passage 16 communicate with each other to send high pressure oil into the cylinder 52, and as a result, the locking piece 70 retreats from the piston chamber 51.
In this state, the piston rod 60 becomes movable.

On the other hand, the oil passage 12 of the output side oil passage of the second electromagnetic switching valve 10 communicates with the high pressure oil passage 16, and the oil passage 11 communicates with the low pressure oil passage 18, so that the g chamber of the piston chamber 51 The pressure of the piston rod 60 is increased and the pressure of the f chamber is decreased.
can move in the direction of arrow e and perform steering.

On the other hand, when returning the rear wheels from the steering position to the neutral position, use the spring offset type solenoid switching valve 9.
2 to the initial position and the second electromagnetic switching valve 10 in the direction opposite to the arrow d, it is possible to return to the neutral position.

The above explanation has been made for the case of steering in only one direction, but it goes without saying that the oil passage configuration including the switching valve may be reversed from the previous explanation in the case of steering in the other direction as well.

(Effects) According to the present invention, the piston that reciprocates within the hydraulic cylinder for rear wheel steering can be used as a component of the piston rod return device. Since it is only necessary to form the hydraulic cylinder into a shape, the processing of the hydraulic cylinder is simpler than that of conventional cylinders, and since only the piston chamber is required, it is possible to prevent the cylinder from becoming larger.

Furthermore, since the pair of locking pieces can be set in a locked position at an intermediate position relative to the piston and in a moving position for steering, there is no need to provide a special structure for setting the position. This makes it possible to simplify the structure. Furthermore, when setting the lock position, the locking pieces interfere with both sides of the piston, so no machining is required on the piston side. This does not require
The structure can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing a conventional example of a rear wheel steering device, and FIG. 2 is a hydraulic circuit diagram showing an embodiment of the present invention. 50... Hydraulic cylinder for rear wheel steering, 51... Piston chamber, 60... Piston rod, 61... Piston, 70... Locking piece serving as a locking member.

Claims (1)

[Scope of Claim for Utility Model Registration] In a rear wheel steering device equipped with a hydraulic cylinder for rear wheel steering in which a piston rod moves left and right from a neutral position to steer the rear wheels, the hydraulic cylinder for rear wheel steering is A piston chamber is formed within the piston rod, and a piston is arranged reciprocatingly within the piston chamber to separate the piston chamber into left and right pressure chambers, and is fixed to the piston rod, and is movable into the piston chamber. a pair of locking members provided on the hydraulic cylinder, the pair of locking members extending along the longitudinal length of the piston at positions corresponding to both sides of the piston in a neutral position of the piston; A rear wheel steering device characterized in that the rear wheel steering device is arranged at appropriate intervals and is provided so as to interfere with both sides of the piston when the piston is projected and to prevent the piston from being displaced from a neutral position.