JPH0617659Y2 - Steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a steering device most suitable for use in a construction vehicle such as a wheel loader.

(Prior Art) In the conventional steering device shown in FIG. 2, the main pump MP and the inflow port 1 of the main valve MV are connected via a flow control valve FV. A throttle 2 is provided between the inlet port 1 and the inflow port 1. The flow rate control valve FV is configured to guide the pressure on the upstream side of the throttle 2 to the one pilot chamber 3.

Further, the main valve MV has a tank port 4 communicating with the tank T and the other pilot chamber 5 of the flow control valve FV.
And a pair of connection ports 7 and 8 and actuator ports 9 and 10 that communicate with the pair of steering cylinders S ₁ and S ₂ .

The connection ports 7 and 8 are always in communication with each other through the throttle 11 regardless of the switching position of the main valve MV.

The steering pump device A that controls the pilot flow rate according to the number of rotations of the steering wheel includes a control pump CP that rotates with the rotation of the steering wheel, a valve RV that also switches according to the rotation of the steering wheel, and a pressure applied to this valve RV. It consists of a pilot pump PP that supplies oil.

The valve RV has a first port 12 into which the oil discharged from the pilot pump PP flows and a second port communicating with the tank T.
13 and the third and fourth ports 14, 15 communicating with the control pump CP
And the fifth and sixth ports communicating with the pilot flow paths 16 and 17
18 and 19 are formed.

The pilot flow passages 16 and 17 communicate with the pilot chambers 20 and 21 of the main valve MV, and also communicate with the connection ports 7 and 8 via the branch passages 22 and 23.

Reference numeral 24 in the figure is a relief valve for controlling the pressure in the other pilot chamber 5 of the flow rate control valve FV to be equal to or lower than a set pressure.

Then, if you keep the handle in the neutral position, the valve RV
Also holds the neutral position shown. When the valve RV is in the neutral position, the pilot flow rates are not supplied to the pilot chambers 20 and 21 of the main valve MV, so that the pilot chambers 20 and 21 have the same pressure and the main valve MV is maintained in the neutral position shown in the figure.

When the main valve MV is in the neutral position, the inflow port 1 is closed, but the pilot port 6 communicates with the tank port 8. In this state, the pressure on one pilot chamber 3 side of the flow rate control valve FV becomes higher than the pressure on the other pilot chamber 5 side, so the flow rate control valve FV holds the position shown in the drawing and the main pump MP The total amount of discharged oil is the working machine circuit PB.
Supply to.

When the handle is turned counterclockwise from the above state, the control pump CP is rotated accordingly, and the valve RV is moved leftward and switched to the right position in the drawing. When the valve RV is thus switched to the right side position, the first port 12 and the fourth port 15 communicate with each other, so that the discharge oil of the pilot pump PP flows into the control pump CP. At this time, control pump CP
Rotates in proportion to the rotation speed of the handle, so that the control pump PP discharges a flow rate proportional to the rotation speed of the handle.

The pilot flow rate thus discharged from the control pump CP is supplied to the one pilot flow passage 16 from the third port 14 to the fifth port 18. At this time, the other pilot flow path 17 communicates with the tank T from the sixth port 19 through the second port 13.

Therefore, the pilot flow rate supplied to the one pilot flow passage 16 is the branch passage 22 → the connection port 7 → the throttle 11
→ connection port 8 → branch passage 23 → other pilot flow passage 17
To the tank T via.

When a flow is generated in the throttle 11 as described above, a pressure difference is generated before and after the flow, but the pressure on the upstream side of the flow is reduced by the main valve MV.
One pilot chamber 20 acts, and the pressure on the downstream side acts on the other pilot chamber 21.

Due to the pressure difference between both pilot chambers 20 and 21, the main valve
The MV moves to the left and switches to the right position in the drawing. Inflow port 1 if the main valve MV switches to the right position
Communicate with both the actuator port 9 and the pilot port 6, and the other actuator port
10 communicates with the tank T via the tank port 4.

Therefore, oil discharged from the main pump MP is one of a rod side chamber of the steering cylinder S _1, is supplied to the bottom chamber of the other steering cylinder S _2, it steers the vehicle to the left.

Then, when the handle is stopped, the discharge amount from the control pump CP becomes zero, so that the differential pressure before and after the throttle 11 disappears and the pressures in the pilot chambers 20 and 21 become equal. Pilot room 2
When the pressures of 0 and 21 become equal, the main valve MV also returns to the illustrated neutral position by the action of the springs 25 and 26, the actuator ports 9 and 10 are closed, and the steering cylinders S ₁ and S ₂ are stopped at the operating position. . That is, the steering position is maintained.

Further, when the handle is turned to the right, which is the opposite direction to the above, the pilot flow rate is supplied to the flow path 17 side. Therefore, the pressure in the pilot chamber 21 of the main valve MV becomes higher than the pressure in the pilot chamber 20, the main valve MV is switched to the left position, and the vehicle is steered to the right in the same principle as above. Let

Then, the switching amount of the MV of the main valve is controlled according to the rotation speed of the handle, that is, the rotation speed of the control pump CP, and therefore, the turning angle of the wheel is determined by the rotation speed of the handle. Become.

When the main valve MV is switched and the discharge oil of the main pump MP is supplied to the steering cylinder as described above, a pressure difference is generated before and after the throttle 2, and the pressure on the upstream side is one of the flow control valves FV. And the pressure on the downstream side acts on the other pilot chamber 5 via the pilot port 6. Therefore, this flow control valve FV
Changes according to the pressure difference, but when steering is operated, a constant control flow rate is preferentially supplied to the steering cylinder, and the excess flow rate is supplied to the working machine circuit.
It supplies to PB.

(Problems to be Solved by the Present Invention) In the conventional steering device as described above, the responsiveness of the steering wheel is always constant even during excavation work or high-speed traveling. Become.

However, it is ideal that the responsiveness of the steering is improved in the actual vehicle operation such as during high-speed running, and the responsiveness is slightly lowered during the excavation work, etc. , There was a problem that it could not be achieved.

The purpose of this device is to improve responsiveness when operating an actual vehicle,
In the case of excavation work, etc., it is to provide a device with reduced responsiveness.

(Means for Solving Problems) In order to achieve the above object, the present invention connects a responsive switching valve between a pair of pilot flow paths, and short-circuits both pilot flow paths via the responsive switching valve. In addition, the responsiveness switching valve is switched to control the flow rate of the short-circuit passage to control the responsiveness of the steering wheel.

(Operation of the present invention) By switching the responsive switching valve to short-circuit both pilot channels, depending on the switching position, one pilot channel is switched to the other pilot channel via the short-circuit channel. Control the flow rate.

When the entire one pilot flow rate is supplied to the pilot chamber, the steering response is improved.

On the other hand, the greater the flow rate passing through the short-circuit flow path, the lower the responsiveness.

(Effect of the Invention) Since the response of the steering can be arbitrarily switched by operating the response switching valve, for example, in the case of actual vehicle operation, the response of the steering is improved,
In the case of excavation work or the like, the responsiveness can be reduced, and an ideal steering state can be obtained.

(Embodiment of the Present Invention) The embodiment of the present invention shown in FIG.
A responsive switching valve V is connected between 6 and 17, and other configurations are the same as those of the above-mentioned conventional one.

Therefore, here, the responsive switching valve V will be described in detail, and the description of the other components will be the same as the above-mentioned conventional description.

In the normal state, the responsive switching valve V holds the illustrated closed position I, but by energizing the solenoid 27, it holds the open position II. Then, in this open position, both pilot channels 16 and 17 are short-circuited via the throttle 28.

Now, when the responsive switching valve V is held in the illustrated closed position I and the handle is turned, the pilot flow rate is entirely the same as in the conventional case and passes through the throttle 11 of the main valve MV.

On the other hand, the responsive switching valve V is excited by exciting the solenoid 27.
When the handle is turned while switching to the open position II, a part of the pilot flow rate supplied to one pilot flow path flows to the other pilot flow path via the throttle 27. The flow rate flowing through the throttle 11 of the main valve MV also becomes relatively small.

Even when the responsive switching valve V is held in the closed position I as described above, the flow rate passing through the throttle 11 of the main valve MV becomes relatively smaller when the responsive switching valve V is held in the open position II. , The differential pressure before and after that is reduced, and the pilot pressure is also reduced.

Therefore, when the responsive switching valve V is switched to the open position II, the responsiveness is slightly lowered.

In the above embodiment, the responsive switching valve V has a solenoid 27.
Is provided and the switching valve V is electrically switched, but it may be manually switched.

Further, a plurality of responsive switching valves V having different openings of the throttle 27 may be provided to increase the number of mode switching.

Further, the responsive switching valve V may of course be configured by a proportional control valve instead of the on / off valve as described above.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional example. A ...... steering pump device, 16, 17 ...... pilot channel, MP ...... main pump, T ...... tank, MV ...... main valve, 20, 21 ...... pilot chamber, S _1, S ₂ ......
Steering cylinder, V ... Responsive switching valve.

Claims (1)

[Scope of utility model registration request] 1. A steering pump device for controlling a discharge amount according to the number of rotations of a steering wheel, a main valve whose switching amount and a switching speed are controlled according to a pilot flow rate from the steering pump device, and these. A pair of pilot flow passages that connect the steering pump device and the pilot chamber of the main valve, a pair of steering cylinders whose expansion and contraction directions are controlled according to the switching direction of the main valve, and steering via the main valve. In a steering device including a main pump communicating with a cylinder and a tank communicating with a steering cylinder via a main valve, a responsive switching valve is connected between a pair of pilot passages, and the responsive switching valve is used. Short-circuit both pilot flow paths and turn off this responsive switching valve. Ete controls the flow rate through the short flow path, the steering apparatus to the configuration control the responsiveness of the steering.