JPH0730454Y2 - Steering control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a steering control device for controlling the steering direction of a vehicle body by hydraulic pressure.

(Conventional Control Device) The conventional steering control device shown in FIG. 2 has a main passage 12 that connects the pump P and the power cylinders 10 and 11.
In addition to the large-capacity steering valve mechanism a, a small-capacity control valve unit b for controlling the large-capacity steering valve mechanism a is provided.

The steering valve mechanism a includes an unload valve U,
The main elements are a switching valve V provided on the downstream side of the unload valve U and port relief valves 13 and 14 connected on the downstream side of the switching valve V.

The control valve unit b is composed of a directional switching valve 15 and a gear pump 16. By turning a handle (not shown), the switching valve 15 is switched to either the left or the right, and the hydraulic oil from the pilot pump 17 is transferred to the above. Supply to the gear pump 16. The gear pump 16 discharges a pilot flow rate proportional to the rotation speed of the handle.

Now, assuming that the handle is rotated to switch the direction switching valve 15 to the right side position in the drawing, the oil discharged from the pilot pump 17 flows into the gear pump 16 via the direction switching valve 15.

At this time, a pilot flow rate proportional to the rotation speed of the handle is discharged from the gear pump 16, and the discharged oil flows into the direction switching valve 15 again, but the discharged oil passes through one pilot flow path 18. And flows into one pilot chamber 19 of the switching valve V. At this time, the other pilot chamber 20 of the switching valve V communicates with the tank T via the other pilot flow passage 21 and the direction switching valve 15.

Further, a stop valve mechanism c is provided in the pilot flow paths 18 and 21 on the downstream side of the control valve unit b.

This stop valve mechanism c includes a pair of stop valves 22, 23.
And pressure-sensing actuated valves 24, 25 as main elements, both of which maintain the pilot channels 18, 21 in the open state when in the normal position shown.

Immediately before reaching the limit steering angle of the vehicle, the stop valves 22 and 23 come into contact with a stopper provided on the vehicle body to switch from the normal position shown to the switching position to close the pilot flow paths 18 and 21. Keep in the state.

When the stop valves 22 and 23 are in the normal position shown in the drawing, they close the passages 27 and 28 communicating with the back pressure chamber 26 of the unload valve U, and the stop valves 22 and 23 are in the switching position. When switched, the passages 27 and 28 are communicated with the tank passage 29. In this way, the back pressure chamber 26 is
When communicating with the tank T via 29, the unload valve U
Opens the valve and puts the pump P in an unloaded state.

Further, the pressure sensing actuating valves 24 and 25 have springs 30 and 31 acting on one of them, and the spring 3
Pilot chambers 32 and 33 are provided on the opposite side of 0 and 31. The load pressure of the power cylinders 10 and 11 is introduced into the pilot chambers 32 and 33 through the parrot passages 34 and 35.

Therefore, when the load pressure of the power cylinders 10 and 11 becomes higher than the set pressure determined by the springs 30 and 31, the pressure sensing operation valves 24 and 25 are switched from the normal position shown to the switching position and the pilot flow passage Close 18 and 21.

In the figure, reference numerals 36 and 37 are bypass passages provided in the stop valve mechanism c, and check valves 38 and 39 that allow only the return flow of the pilot passages 18 and 21 are provided.
The return oils of 18 and 21 are returned to the directional control valve 15 without passing through the pressure sensing operation valves 24 and 25 and the stop valves 22 and 23.

Therefore, depending on the direction of rotation of the handle, the directional valve
When 15 is switched, the pilot flow rate proportional to the rotation speed of the handle flows into one of the pilot chambers 19 or 20 of the switching valve V to switch the switching valve V.

Now, assuming that the switching valve V is switched to the right position in the drawing,
The oil discharged from the pump P flows into the bottom side chamber 10a of one cylinder 10 and the rod side chamber 11a of the other cylinder 11 via the check valve 40 provided in the switching valve V, and the steering direction of the vehicle is changed. Control.

Further, when the switching valve V is switched as described above, the one pilot chamber 19 communicates with the other pilot chamber 20 via the inside of the switching valve V, and the variable throttle is included in the communication process. 41 are provided. The variable throttle 41 changes its opening depending on the amount of movement of the spool of the switching valve V, and the differential pressure generated before and after this throttle 41 is determined by the opening of the throttle 41 and the pilot flow rate. .

Then, the front pressure of the throttle 41 acts as the pilot pressure on the pilot chamber 19 to specify the switching amount of the switching valve V.

In this way, the power cylinders 10 and 11 operate to switch the direction of the vehicle, but as described above, immediately before the limit steering angle, the stopper provided on the vehicle body comes into contact with the stop valve 22. 22 is switched to the switching position and the pilot channel 18 is closed. If the pilot channel 18 is closed,
Since the differential pressure across the variable throttle 41 disappears, the switching valve V immediately returns to the illustrated neutral position, and the power cylinders 10, 11
Stop supplying hydraulic oil to the.

That is, the stop valve 22 is closed and the power cylinders 10 and 11 are stopped immediately before the vehicle body collides with the stopper, so that the impact due to the collision can be alleviated. Further, if the pilot flow path 18 is closed as described above, the steering resistance becomes large, so that the driver knows that he cannot turn the steering wheel any more.

When the stop valve 22 is closed as described above, the passage 27 communicates with the tank T through the tank passage 29, so that the unload valve U is opened to maintain the pump P in the unloaded state and to reduce its horsepower. Minimize losses.

Further, even if the limit steering angle is not reached as described above, when the load pressure of the power cylinders 10 and 11 becomes equal to or higher than the set pressure, the pressure sensing operation valves 24 and 25 are closed, so when the stop valves 22 and 23 are closed. Will be similar to.

Since the pressure sensing operation valves 24 and 25 are switched in this way, for example, when the wheel hits an obstacle before the stopper of the vehicle body hits the stop valves 22 and 23, the driver can move the steering wheel further. You will know that you cannot cut it. Therefore, it is not necessary to consider the horsepower loss when the steering wheel operation is continued without knowing that the steering cannot be performed.

(Problems to be Solved by the Present Invention) In the conventional device as described above, when the stop valves 22 and 23 are closed, the pilot flow paths 18 and 21 between the steering valve mechanism a and the stop valve mechanism c are closed. Pilot pressure accumulates in.

When the pilot pressure remains in this way, the switching valve V
Is delayed in returning to the neutral position, so that the oil discharged from the pump P is supplied to the power cylinders 10 and 11 during that time.

Therefore, there was a problem that the response was delayed and the steering was excessively cut through despite the stop valves 22 and 23 being closed.

An object of the present invention is to provide a device that improves the responsiveness of the steering valve mechanism when the stop valve mechanism closes the pilot flow path, and prevents excessive steering and the like.

(Means for Solving Problems) The present invention is characterized in that the stop valve mechanism is provided with a flow passage that connects the pilot flow passage to the tank when the stop valve mechanism closes the pilot flow passage.

(Operation of the present invention) Even if the pilot flow passage is closed as described above, the pilot flow passage communicates with the tank, so that the pressure is not accumulated therein.

(Effects of the Invention) As described above, since the pressure is not accumulated in the pilot flow path and the response of the steering valve mechanism to the operation of the stop valve mechanism is improved, the problem such as over-turning of the handle does not occur. .

(Embodiment of the present invention) The present invention is an improvement of the structure of the stop valve mechanism c, and other configurations are the same as the above-mentioned conventional one. Therefore, the improvements will be described below, and the description of FIG.

The embodiment of the present invention shown in FIG. 1 is a conventional stop valve.
This stop valve 2 has more ports than 22 and 23
When the passages 2 and 23 are switched, the passages 42 and 43 are connected to the tank passage 29. One end of the passages 42 and 43 is a pilot passage downstream of the pressure sensing operation valves 24 and 25.
It connects to 18 and 21.

Therefore, when the stop valves 18 and 21 are closed, the pilot flow paths 18 and 21 are automatically communicated with the tank T, so that the pilot flow paths 18 and 21 are not filled with pressure.

When the stop valve mechanism is switched to the switching position,
In this embodiment, the stop valves 22 and 23 are used as a mechanism for connecting the pilot passage between the stop valve mechanism and the steering valve mechanism to the tank.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional control device. 10, 11 ... Power cylinder, a ... Steering valve mechanism, V ... Switching valve, 18, 21 ... Pilot flow path, c ...
… Stop valve mechanism, 22, 23 …… Stop valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Shown 60-132977 (JP, U) Shown 61-247572 (JP, U) Shown 61-141175 (JP, U) Shown 59- 194603 (JP, U) Actually open Sho 60-102073 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A power cylinder for specifying a steering direction, a switching valve for controlling hydraulic oil supplied to the power cylinder, a control valve unit for controlling a pilot flow rate supplied to a pilot chamber of the switching valve, and a control valve unit. A stop valve connected to a pilot channel connecting the valve unit and the pilot chamber of the switching valve is provided, and the stop valve mechanism opens the pilot channel at its normal position and this pilot channel at the switching position. In the squaring control device configured to close the switch valve and to switch the stop valve mechanism to the switching position immediately before the limit steering angle, when the stop valve mechanism is switched to the switching position, the stop valve mechanism and the steering valve mechanism are The pilot flow path between The threaded to passage, provided in the stop valve mechanism steering control device.