JPS5815731Y2 - Hydraulic pressure system switching control device - Google Patents

Description

[Detailed Description of the Invention] The present invention is a switching control device for a hydraulic system, and more specifically, the switching control device uses pilot pressure supplied from another control valve to switch a switching valve that switches the direction of hydraulic pressure acting on an actuator. This invention relates to a switching control device for a hydraulic system.

Control using hydraulic pressure has developed in recent years and is used in various hydraulic systems.

Generally, such a hydraulic system has a switching valve that sends working fluid to the actuator a, and a hydraulic control valve C that controls the signal pressure to operate the switching valve, as shown in Fig. 1. The difference in output pressure of each valve required each hydraulic pump dte to be a separate source of hydraulic pressure.

In this case, if the actuator a is a servo mechanism of a variable device of a variable displacement hydraulic pump, the set pressure of the relief valve f of the hydraulic pressure source pump e of the control valve C is changed over. It is possible to design the set pressure of the valve to be equal to the set pressure of the valve.

However, even in this case, in order to ensure the output signal pressure of the control valve C, it is necessary to prevent a drop in the discharge pressure of the pump e, whereas depending on the external force of the actuator a, the discharge of the hydraulic source pump d of the switching valve The pressure is often significantly lower than the set pressure of the IJ 17 valve.

Therefore, the relief valve f at the outlet of each hydraulic pressure source, ? It was not possible to use the same hydraulic pump for these hydraulic pressure sources even if the set pressures were the same.

This made the control system complicated. Although it is generally sufficient for the output power of a control valve to be extremely small, in actual design of this type of valve, a considerable flow rate is required from the hydraulic pressure source to ensure reliable operation.

Especially for the purpose of detecting the input rotational speed of the hydraulic pressure source of the control valve.
When detecting the pressure drop due to the discharge flow rate of this pump, in order to ensure the detection, it is several tens of times the control valve output power required to ensure the operation of the control valve based on the detection result. power is required from the hydraulic pressure source.

Therefore, if the same hydraulic pump can be used as the hydraulic pressure source for the control valve and the switching valve, not only will the control system become simpler, but the driving power required for the hydraulic pressure source for control will be reduced.

The present invention was developed with the above in mind, and it is possible to make the hydraulic pressure source for sending the working fluid to the actuator through the switching valve and the hydraulic pressure source for switching the switching valve to be the same. Moreover, even if the hydraulic pressure supplied to the actuator fluctuates, the hydraulic pressure that switches the switching valve can be kept constant.
The purpose is to enable stable switching control.

The present invention uses a hydraulic system that includes a switching valve that sends working fluid to an actuator, a control valve that controls the signal pressure that switches and operates the switching valve, and a valve box that has an inlet port, a drain port, and a charge port. It is slidably fitted into the valve boxes of and, and is moved to one side by the inlet pressure P1 acting on the inlet port, first communicating the artificial port and the charge port, and then connecting the inlet port and the drain port. and a spool that communicates with the above inlet pressure P1.
A sequence relief valve is constructed by a spring biased in a direction to move against the pressure, and the input port of the sequence relief valve is connected to a signal pressure acting part of the switching valve via a hydraulic pressure source and the control valve. The charge port is connected to the actuator via the switching valve.

The operation of the hydraulic system switching control device having the above configuration is as follows.

That is, when the charge pump is driven and the inlet pressure of the inlet port increases, this pressure acts on the signal pressure acting part of the switching valve through the control valve, causing the switching valve to switch, and at the same time, the sequence relief valve The spool moves against the spring, first, the inlet port and the charge port communicate with each other, and the working fluid from the inlet port is supplied to the actuator via the switching valve.

In a state where the inlet port and the charge port are in communication, even if the pressure at the charge port decreases due to fluctuations in the external force of the actuator, the communication is restricted and the pressure at the inlet port does not decrease.

Furthermore, when the pressure in the charge port rises above a predetermined pressure, the drain port communicates with the inlet port to prevent further pressure rise.

The effects of the above configuration are as follows.

In other words, only one hydraulic pump is required compared to the conventional two, and the space required for the hydraulic pressure source can be reduced.

Further, even if the pressure supplied to the actuator changes, the control hydraulic pressure does not change much, and stable switching control can be performed.

Embodiments of the present invention will be described below based on the drawings.

In the figure, reference numeral 1 denotes a spool slidably fitted into a valve box 2, which is biased in one direction by a spring 3.

Then, on one end side of this spool 1, the spring biasing force is applied]
There is an opposite input port 4 on the opposite side.

The valve box 2 has a drain port 5 and a charge port 6, while the spool 1 has a liquid switching supply section 1at1b that communicates these with the inlet port 4.

The relationship between these forces 5 and others is such that when the spool 1 is moving due to the biasing force of the spring 3, both ports 5 and 6 are blocked, and when the spool 1 moves against the spring force, the ports 5 and 6 are closed. The charge port 6 is in communication, and then the drain port 5 is also in communication.

The inlet boat 4 is connected to a charge pump 8 via a flow rate detection mechanism 7, and the charge port 6 is connected to an actuator 10 via a switching valve 9.

The pilot circuit of the actuating portion of the switching valve 9 communicates with the inlet boat 4 via a control valve 11 whose switching is controlled by pilot pressure from the flow rate detection mechanism γ.

12 is an adjustment screw for adjusting the biasing force of the spring 3.

For the above configuration, the hydraulic fluid supplied from the charge pump 8 is guided to the inlet port 4.

The inlet pressure P1 of the inlet port 4 is equal to the supply pressure of the control valve 11.

When this inlet pressure P1 is small, the spool 1 is moved to the left in the figure by the biasing force of the spring 3, and the inlet port 4 is used for drain port 5 and charge port 6.
is closed.

When the charge pump 8 is driven and the inlet pressure P1 of the inlet port 4 rises, the spool 1 is moved to the right against the spring 3.

In this way, the inlet port 14 and the charge port 6 first communicate with each other, and the operating fluid is supplied to the switching valve 9.

At this time, even if the inlet pressure of the switching valve 9, that is, the charge pressure P2 decreases due to the external force of the actuator 10, the communication opening between the inlet boat 4 and the charge port 6 is restricted, so the pressure P of the inlet port 4 does not decrease. , therefore, there is no change in the signal pressure that operates the switching valve 9, and the switching valve 9 operates at its switching position 1.
maintain the condition.

Further, when the external force on the actuator 10 is large or when the switching valve 9 is closed, the charge pressure P2 increases, and the pressure P1 at the inlet port 4 also increases slightly.

As a result, the spool 1 moves further to the right against the spring 3, so that the inlet port 4 and the drain port 5 are in communication with each other, and the hydraulic fluid supplied to the inlet port 4 passes through the drain port 5 to the tank. be returned.

As a result, the inlet pressure P1 and the charge pressure P2 do not rise by -2 degrees from the pressure in this state.

This thick blade setting is adjusted by an adjusting screw 12.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional hydraulic control system, and FIG. 2 is a circuit diagram of a hydraulic control system using a sequence relief valve according to the present invention. 1 is the spool, 2 is the valve box, 3 is the spring, 4 is the entrance port,
5 is a drain port, 6 is a charge port, 8 is a charge pump, 9 is a switching valve, 10 is an actuator, and 11 is a control valve.

Claims (1)

[Scope of utility model registration request] A valve that has an inlet boat 4, a drain port 5, and a charge port 6 in a hydraulic system that includes a switching valve 9 that sends working fluid to an actuator 10, and a control valve 11 that controls a signal pressure that switches and operates the switching valve 9. The box 2 is slidably fitted into the valve box 2 of the box 2, and is moved to one side by the inlet pressure P1 acting on the inlet port 4 to connect the inlet port 4 and the charge port 6; Next, a sequence relief valve is constructed by a spool 1 that communicates between the inlet boat 4 and the drain port 5, and a spring 3 that is attached in a direction that moves the spool 1 against the inlet pressure P1.
Connect the inlet boat 4 of this sequence relief valve to a hydraulic pressure source.
and a switching control device for a hydraulic system, characterized in that the charge port 6 is connected to the signal pressure acting part of the switching valve via the control valve 11, and the charge port 6 is connected to the actuator 10 via the switching valve 9.