JPH03144101A - Multistage pressure controlling method for hydraulic circuit - Google Patents

Abstract

PURPOSE:To quicken responsiveness at a low cost by controlling a pair of solenoid proportional pressure controlling valves which are inserted in a vent circuit of a relief valve for controlling pressure of hydraulic circuit through a switching solenoid directional changeover valve so that one of them is operated under a next preset pressure when the other is operated. CONSTITUTION:A solenoid directional changeover valve 5 for selecting either one of a pair of solenoid proportional pressure controlling valves 6, 7 is inserted in a vent circuit 4A of a relief valve 4 which controls hydraulic pressure to an actuator 3. The controlling valves 6, 7 are controlled by signal switchers C12, C13 for selecting respective one of signals form program controlling pressure setters 14, 15, while the signals are switched alternately by a signal switcher B11. The solenoid directional changeover valve 5 is controlled by a pressure controlling device including a signal switch A8. One of the solenoid pressure controlling valves 6, 7 is operated, and the other is operated under a next preset pressure before switching according to the program. Controlling is preformed with quick responsiveness at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to pressure control in a hydraulic circuit, and more particularly to a pressure control method capable of controlling the pressure to be varied in multiple stages using an electromagnetic proportional pressure control valve with a quick response.

<Conventional method> Conventionally, when controlling the pressure using an electromagnetic proportional pressure control valve to change the pressure in multiple stages, the amount of electricity (current value) input to the electromagnetic proportional pressure control valve is changed using a pressure change switching signal, thereby changing the pressure. The spool is moved inside the control valve at a position 1 necessary for predetermined pressure control. <Problem to be solved by the invention> Therefore, the pressure change is completed within 1 after the pressure change control signal is issued. If it takes time to change the pressure from O to MAXl, it will take 50 to 300 minutes depending on the size of the pressure control valve.
m5ec time was required. For the above reasons, when it is necessary to increase the response speed in control that changes pressure in multiple stages, a servo valve is used instead of an electromagnetic proportional pressure control valve, which takes time to change the pressure. It had the disadvantage of high cost.

The present invention eliminates these drawbacks, and its purpose is to provide a multi-stage pressure control method for a hydraulic circuit that is low in cost and has a high response speed.

<Means for Solving the Problems> In order to eliminate the above-mentioned drawbacks, the present invention provides a relief valve that controls the pressure in a hydraulic circuit, and a pair of electromagnetic proportional pressure control valves that control the pressure in the vent circuit of the relief valve. , an electromagnetic directional control valve for controlling the pressure in the vent circuit of the relief valve depending on whether the pair of electromagnetic proportional pressure control valves is inverted; A pressure setting device that sets the pressure value of
One of the many pressure values set in the pressure setting device is selected, and a desired pressure program control is performed with signal switching devices C and D connected to respective solenoids of the pair of electromagnetic proportional pressure control valves. A signal switch B receives a setting value switching signal for switching the switching signal channels ch and D alternately, and after the signal switch B sends a signal for switching the signal switches C and D, a predetermined A pressure control device of a hydraulic circuit consisting of a signal switch A that operates in response to the signal after a period of time has elapsed and controls the electromagnetic directional control valve controls the pair of electromagnetic proportional control valves at a predetermined time before starting the desired pressure program control. One side of the pressure control valves is operated at a predetermined pressure, and after the predetermined time has elapsed, the program control is started at the predetermined pressure of the electromagnetic proportional pressure control valve on the one side, and after the pressure program control is started. When switching the set pressure, when one side of the electromagnetic proportional pressure control valve is selected, the other side of the electromagnetic proportional pressure control valve is operated in advance at the next set pressure value a predetermined time before the quantity valve is selected. This is a multi-stage pressure control method characterized by the following.

<Operation> According to the present invention, when the electromagnetic switching valve is switched and one side of the pair of electromagnetic relief valves is selected, the electromagnetic relief valve on the same side has already been activated for a predetermined period of time. Therefore, the specified pressure is applied.

<Example> Next, one example of the present invention will be described as a second example with reference to Fig. 1 and Fig. 2.
As shown in Figure (1), P1□, P2□, P1□, P2□...
``El'' and ``L'' will be explained in the hydraulic control circuit that performs multi-stage pressure control in 8 stages of 1m1P2n.

A pump 1 pressurizes oil in a tank 2 and sends it to an actuator 3. 4 is a relief valve provided on the discharge side of the pump 1. Vent circuit 4 of the same relief valve 4
A is provided with a pair of electromagnetic proportional pressure control valves (hereinafter referred to as electromagnetic IJ IJ-) valves 6 and 7 via an electromagnetic directional control valve 5, and by switching the electromagnetic directional control valve 5, the pair of electromagnetic Either one of the IJ and IJ valves 6 and 7 controls the pressure of the vent circuit 4A.

The electromagnetic IJ valves 6 and 7 are connected to the pressure setting device 14.
and pressure set to 15 P11+P121P13I
P1m, P211P2□, and P23+''2□ are activated.The pressures set in the pressure setting devices 14 and 15 are transmitted from the signal switch Bll which acts on the signal switch CI2 and the signal switch D13, respectively. The signals act on the electromagnetic relief valves 6 and 7 in the predetermined order shown in FIG. 2 (2) and (3), respectively.

The signal switch Bll receives a signal from a detection device (not shown) that detects the operation of the actuator 3, and sends the signal to the signal switch C12 and the signal switch D13 according to a predetermined position, time, etc. The electromagnetic relief valve 6 or the electromagnetic relief valve 7 is operated at a predetermined pressure at a predetermined position or time, and the electromagnetic switching valve 5 is operated at a predetermined pressure.
Switching control is also performed. That is, the electromagnetic relief valve 6 control signal emitted from the signal switch Bll, the electromagnetic I
OR circuit 101 which generates a signal in response to one of the JIJ-F valve 7 control signals.Next, a timer 9 which is activated by a signal from the OR circuit 10, and a timer 9 which is activated after a predetermined set time has elapsed. The timeout signal issued
A signal switch A8 for switching solenoids 5A and 5B of the electromagnetic switching valve 5 is connected.

The apparatus is constructed as described above, and the operation of the apparatus according to the present invention will now be described. In response to a signal from the above-mentioned detection device of the actuator 3, a signal is first applied from the signal switch B11 to the signal switch C12, and the first PLL set in the pressure program control shown in FIG. 2 (1) is selected. The electromagnetic relief valve 6 has a pressure P□, preferably the spool inside the valve (
(not shown) starts moving.

At the same time, the timer 9 also starts counting a time Δt1 that is sufficient for the spool of the electromagnetic relief valve 6 to move and reach the set pressure P1□.When the timer 9 counts a predetermined time Δt1, , the signal switch A8 acts on the solenoid 5B of the electromagnetic switching valve 5, the electromagnetic switching valve 5 is in the right position in the figure, and the vent circuit 4A becomes the set pressure P1□ of the electromagnetic relief valve 6.

Next, when the actuator 3 sends a signal to the signal switch Bll from the detection device to the second set value P2□ of the pressure program control shown in FIG. 2 (1), a signal is sent to the signal switch D13. Solenoid relief valve 7
As soon as the pressure reaches the predetermined pressure P2□, the timer 9 starts operating as described above, and when the time Δt1 has counted out, a signal acts on the signal switch A8, and the signal switch A8 receives the timeout signal. In response, a signal is sent to the solenoid 5B, the electromagnetic switching valve 5 is placed in the position shown, and the circuit by the electromagnetic relief valve 7 is activated. As aforementioned,
The set pressure P2□ of the electromagnetic relief valve 7 has been activated for a predetermined time △t1 before the electromagnetic switching valve 5 switches, so that the electromagnetic switching valve 5 switches at the time when the electromagnetic relief valve 7 reaches the predetermined pressure P2□. It has become.

In this way, the pressure program control is performed in the same manner after the third, and as shown in FIG. 2 (1), the predetermined pressure P1□,
P2□, P13 . . . so that the electromagnetic relief valves 6 and 7 are switched alternately, without being affected by the delay in the sprue operation time of the electromagnetic relief valves 6 and 7. Multi-stage pressure control as shown in Figure (1) can be realized.

Effects> Since the multi-stage pressure control method of the present invention is configured as described above, a much faster response speed can be obtained compared to the conventional method of adjusting the amount of electricity of an electromagnetic relief valve, and the servo valve There is no need to use expensive valves such as

In other words, in the above embodiment, the setting pressure of each electromagnetic IJ valve is set to 8 steps, with 4 steps each.
Of course, the pressure control is not limited to this, and any number of multistage pressure controls are possible.

4,

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the pressure control situation in the embodiment shown in FIG. 4... Relief valve, 4A... Vent circuit, 5...
Electromagnetic directional control valve, 6, 7...Electromagnetic proportional pressure control valve, 8
...Signal switch A111...Signal switch B112.
...Signal switch C113...Signal switch R, 14.
15...Pressure setting device.

Claims (1)

[Claims] A relief valve that controls the pressure of the hydraulic circuit, a pair of electromagnetic proportional pressure control valves that controls the pressure of the vent circuit of the relief valve, and a pressure control valve that controls the pressure of the vent circuit of the relief valve. an electromagnetic directional control valve for controlling each of the pair of electromagnetic proportional pressure control valves in a multi-stage program, a pressure setting device in which a large number of pressure values are set, and pressure values set in the pressure setting device; A signal switch C that selects one pressure value from a large number of pressure values and is connected to each solenoid of the pair of electromagnetic proportional pressure control valves.
and D, and a signal switch B that alternately switches the switching signals C and D in response to a set value switching signal for performing desired pressure program control; and signal switch C and D from the signal switch B. The desired pressure program control is started by a pressure control device of a hydraulic circuit consisting of a signal switch A that operates in response to a predetermined period of time after a switching signal is transmitted and controls the electromagnetic directional switching valve. At the previous predetermined time, one side of the pair of electromagnetic proportional pressure control valves is operated at a predetermined pressure, and after the predetermined time has elapsed, the program control is performed to operate the one side electromagnetic proportional pressure control valve at the predetermined pressure. When switching the set pressure after starting pressure program control, when one side of the electromagnetic proportional pressure control valve is selected, the other side of the electromagnetic proportional pressure control valve is switched in advance for a predetermined time before the same valve is selected. A multi-stage pressure control method characterized by operating at the next set pressure value.