JPH0357322B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to pressure control in a hydraulic circuit, and 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, control for changing pressure in multiple stages using an electromagnetic proportional pressure control valve was performed using a pressure change switching signal.
The amount of electricity (current value) input to the electromagnetic proportional pressure control valve is changed, thereby moving the spool inside the pressure control valve to the position required for predetermined pressure control.

<Problems to be Solved by the Invention> Therefore, it takes a long time from when the pressure change control signal is issued until the pressure change is completed.
In the case of changing the pressure up to MAX, a time of 50 to 300 msec was required, depending on the size of the pressure control valve. 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 switching valve for controlling the pressure in the vent circuit of the relief valve by one of the pair of electromagnetic proportional pressure control valves, and a plurality of electromagnetic directional control valves for controlling each of the pair of electromagnetic proportional pressure control valves in a multi-stage program. A pressure setting device that sets the pressure value of
A signal switching device C that selects one pressure value from a large number of pressure values set in the pressure setting device and is connected to each solenoid of the pair of electromagnetic proportional pressure control valves.
and D, 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 a signal switch C and a signal switch from the signal switch B, and The desired pressure program control is performed by a pressure control device of a hydraulic circuit comprising a signal switch A that is activated after a predetermined time has elapsed after the signal for switching D is transmitted and controls the electromagnetic directional switching valve. At a predetermined time before the start, 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 by operating the one side of the electromagnetic proportional pressure control valve on the one side. Starting at a given pressure,
When switching the set pressure after starting pressure program control, if one side of the electromagnetic proportional pressure control valve is selected,
The multi-stage pressure control method is characterized in that the electromagnetic proportional pressure control valve on the other side is operated at the next set pressure value in advance a predetermined time before the selected valve is selected.

<Operation> According to the present invention, when the electromagnetic switching valve switches and one side of the pair of electromagnetic relief valves is selected, the electromagnetic relief valve on the same side has already been operated for a predetermined time. It has become a specified pressure.

<Example> Next, an example of the present invention is shown in FIG. 2 1 with reference to FIGS. 1 and 2, P ₁₁ , P ₂₁ , P ₁₂ , P ₂₂ . . .
An example of a hydraulic control circuit that performs multistage pressure control in eight stages of P _1n and P _2o will be explained.

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. A pair of electromagnetic proportional pressure control valves (hereinafter referred to as electromagnetic relief valves) 6 and 7 are provided in the vent circuit 4A of the relief valve 4 via an electromagnetic directional switching valve 5. Either one of the pair of electromagnetic relief valves 6 and 7 is connected to the vent circuit 4
It is designed to control the pressure of A.

The electromagnetic relief valves 6 and 7 are connected to the pressure setting device 1.
Pressures set at 4 and 15 P ₁₁ , P ₁₂ , P ₁₃ ,
It operates with P _1n , P ₂₁ , P 22 , P ₂₃ , _and P _2o . The pressures set in the pressure setting devices 14 and 15 are controlled by the electromagnetic relief valves in the predetermined order shown in FIG. 6 and 7, respectively.

The signal switch B11 receives a signal from a detection device (not shown) that detects the operation of the actuator 3, and transmits 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 7 is operated at a predetermined pressure at a predetermined position or time, and switching control of the electromagnetic switching valve 5 is also performed. That is, an OR circuit 10 generates a signal based on one of the signals for controlling the electromagnetic relief valve 6 and the signal for controlling the electromagnetic relief valve 7 generated from the signal switch B11, and then the timer 9 operates based on the signal from the OR circuit 10. A signal switch A8 is wired to switch the solenoids 5A and 5B of the electromagnetic switching valve 5 in response to a timeout signal issued by the timer 9 after a predetermined set time has elapsed.

The apparatus is constructed as described above, and the operation of the apparatus according to the present invention will now be described. The signal switch B1 is first activated by a signal from the above-mentioned detection device of the actuator 3.
1, _a signal acts on the signal switch C12, and the first set P ₁₁ of the pressure program control shown in FIG.
A spool (not shown), preferably within the valve, begins to move.

At the same time, the timer 9 also starts counting the time △t ₁ that is sufficient for the spool of the electromagnetic relief valve 6 to finish moving and reach the set pressure P _{11 .} When counting, the signal switch A8 acts on the solenoid 5B of the electromagnetic switching valve 5, the electromagnetic switching valve 5 moves to the right position in the figure, and the vent circuit 4A becomes the set pressure _P11 of the electromagnetic relief valve 6.

Next, when the actuator 3 sends a signal to the signal switch B11 from the detection device to reach the second set value _P21 of the pressure program control shown in FIG. 1, a signal is then sent to the signal switch D13. As soon as the electromagnetic relief valve 7 starts operating to reach the predetermined pressure P ₂₁ , the timer 9 starts operating as described above, and when the time Δt ₁ has counted out,
The signal acts on the signal switch A8, and the signal switch A8
8 receives the timeout signal and solenoid 5
A signal is sent to B, the electromagnetic switching valve 5 is placed in the position shown, and the circuit by the electromagnetic relief valve 7 is activated. As mentioned above, the set pressure P ₂₁ of the electromagnetic relief valve 7 is activated for a predetermined time Δt ₁ before the electromagnetic switching valve 5 switches, and the electromagnetic switching is performed at the time when the electromagnetic relief valve 7 reaches the predetermined pressure P ₂₁ . Valve 5 is adapted to switch.

In this way, the pressure program control is performed in the same manner from the third time onward, by alternately switching the predetermined pressures P ₁₂ , P ₂₂ , P ₁₃ . Solenoid relief valve 6
and 7 without being subject to the delay in sprue operation time,
Moreover, multi-stage pressure control as shown in FIG. 2 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 it can be used in a manner similar to a servo valve. There is no need to use expensive valves.

In the above embodiment, the set pressure of each electromagnetic relief valve is set to 4 stages, and an 8-stage pressure program is used, but of course, the pressure program is not limited to this, and any number of multi-stage pressure control is possible.

[Brief explanation of drawings]

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...
...Solenoid directional switching valve, 6,7...Solenoid proportional pressure control valve, 8...Signal switch A, 11...Signal switch B, 12...Signal switch C, 13...Signal switch D, 14 , 15...Pressure setting device.

Claims (1)

[Claims] 1 A relief valve that controls the pressure of the hydraulic circuit, a pair of electromagnetic proportional pressure control valves that control the pressure of the relief valve and the vent circuit, and a pressure in the vent circuit of the relief valve that controls the pressure of the pair of electromagnetic proportional pressure control valves. an electromagnetic directional switching valve for controlling each of the pair of electromagnetic proportional pressure control valves; a pressure setting device in which a large number of pressure values are set for controlling each of the pair of electromagnetic proportional pressure control valves in a multi-stage program; The controller selects one pressure value from a large number of pressure values, and also sends a set value switching signal to signal switchers C and D connected to the respective solenoids of the pair of electromagnetic proportional pressure control valves to perform desired pressure program control. a signal switch B that receives the signal and alternately switches the switching signals C and D; and a signal switch C from the signal switch B.
and a signal switch A that operates in response to a predetermined period of time after the signal for D switching is transmitted and controls the electromagnetic directional control valve. At a predetermined time before the start of control, one side of the pair of electromagnetic proportional pressure control valves is operated at a predetermined pressure, and after the elapse of the predetermined time, the program control is performed on the one side of the electromagnetic proportional pressure control valve. Starting at the predetermined pressure, when switching the set pressure after starting the 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 a predetermined time before the same valve is selected. A multi-stage pressure control method characterized by operating the next set pressure value in advance.