JPH0357323B2 - - Google Patents

Description

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

<Conventional method> Conventionally, control to change the flow rate in multiple stages using an electromagnetic proportional flow control valve was performed using a flow rate change switching signal.
The amount of electricity (current value) input to the electromagnetic proportional flow control valve is changed, thereby moving the spool inside the flow control valve to the position required for predetermined flow control.

<Problems to be Solved by the Invention> Therefore, it takes time from when the flow rate change control signal is issued until the flow rate change is completed.
In the case of changing the pressure up to MAX, a time of 70 to 300 msec was required, depending on the size of the flow 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 flow control valve, which takes time to change the flow rate. had the disadvantage of high cost.

The present invention eliminates these drawbacks, and its purpose is to provide a multi-stage flow rate 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 for controlling the flow rate of hydraulic oil supplied to any actuator, in order to control the flow rate of hydraulic oil supplied to an arbitrary actuator, the hydraulic oil is arranged in parallel in the inflow circuit to the working side oil chamber of the actuator. a pair of electromagnetic proportional flow control valves, an electromagnetic directional switching valve that switches to any one of the same pair of electromagnetic proportional flow control valves in order to use one of the same pair of electromagnetic proportional flow control valves; A flow rate setting device in which a large number of flow values are set for controlling each flow rate control valve in a multi-stage program; Signal switchers C and D connected to respective solenoids of the proportional flow rate control valve, and a signal switcher that alternately switches the switching signals C and D in response to a set value switching signal for performing desired flow rate program control. B, and a signal switch A that operates in response to a predetermined period of time after the signal for switching between the signal switch C and D is transmitted from the switch signal switch B, and controls the electromagnetic directional control valve. The hydraulic circuit flow control device consisting of
At a predetermined time before starting the desired flow rate program control, the - side of the pair of electromagnetic proportional flow control valves is operated at a predetermined flow rate, and after the predetermined time has elapsed, the program control is operated by the - side electromagnetic valve. When starting with the predetermined amount of the proportional flow control valve, and when switching the set flow rate after starting the flow rate program control, when the - side electromagnetic proportional flow control valve is selected, the other side is changed for a predetermined time before the same valve is selected. This multistage flow control method is characterized in that an electromagnetic proportional flow control valve is operated in advance at the following set flow value.

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

<Example> Next, referring to FIGS. 1 and 2, an example of the present invention is shown in FIG. 2 (1), where V ₁₁ , V ₂₁ , V ₁₂ , V ₂₂ . . .
An example of a hydraulic control circuit that controls the flow rate in eight stages of V _1n and V _2o will be explained.

Pump 1 pressurizes oil in tank 2, and after passing through electromagnetic directional valve 3, the oil flows into actuator 6 via either a pair of electromagnetic proportional flow control valves 4 or 5. The electromagnetic proportional flow control valves 4 and 5 control the flow rates V ₁₁ , V ₁₂ , V ₁₃ , V _1n and V ₂₁ , V ₂₂ , set in the flow rate setting devices 14 and 15, respectively.
V ₂₃ and V _2o , and the flow rates set in the flow rate setting devices 14 and 15 are controlled by signals from the signal changeover device B10 acting on the signal changeover device C11 and the signal changeover device D12, respectively. 2
The electromagnetic proportional flow control valves 4 and 5 are actuated in a predetermined order shown in FIGS. (2) and (3).

The signal switch B10 receives a signal from a detection device (not shown) that detects the operation of the actuator 6, and transmits the signal to the signal switch C11 and the signal switch D12 according to a predetermined position, time, etc. The electromagnetic proportional flow control valve 4 or electromagnetic proportional flow control valve 5 is operated at a predetermined flow rate at a predetermined position or time, and switching control of the electromagnetic switching valve 3 is also performed. . That is, the DR circuit 9 generates a signal in response to either a signal for controlling the electromagnetic proportional flow control valve 4 or a signal for controlling the electromagnetic proportional flow control valve 5 issued from the signal switch B10, and then it is activated by a signal from the DR circuit 9. A timer 8 is connected to the timer 8, and a signal switching A7 is connected to switch the solenoids 3A and 3B of the electromagnetic switching valve 3 in response to a timeout signal from the timer 8 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. A signal from the above-mentioned detection device of the actuator 6 first causes a signal from the signal switch A7 to act on the signal switch C11, and the second
The first set V ₁₁ in the flow rate program control shown in Figure (1) is selected, and the electromagnetic proportional flow control valve 4 is set to the spool (not shown) in the valve as much as possible to the pressure V ₁₁ .
starts moving. At the same time, the timer 8 also starts counting a time Δt ₁ that is sufficient for the spool of the electromagnetic proportional flow control valve 4 to finish moving and reach the set flow rate, and the timer 8 starts counting a predetermined time Δt ₁ . When it goes out, signal switch A7 switches to solenoid switch valve 3.
The solenoid 3B is actuated, the electromagnetic switching valve 3 is placed in the left position in the figure, and the circuit becomes the set flow rate V ₁₁ by the electromagnetic proportional flow control valve 4.

Next, when the actuator 6 sends a signal to the signal switch B10 from the detection device to reach the second set value V ₂₁ of the flow rate program control shown in FIG. 2(1), a signal is sent to the signal switch D12. When the electromagnetic proportional flow control valve 5 starts operating as much as possible to obtain the predetermined flow rate _V21 , the timer 8 starts operating as described above, and when the time _Δt1 has counted out, the signal acts on the signal switch A7. , the signal switching device A7 receives the time-out signal, sends a signal to the solenoid 3A, and sets the electromagnetic switching valve 3 to the right position as shown in the figure, so that a circuit based on the electromagnetic proportional flow control valve 5 is activated. As mentioned above, the set pressure V ₂₁ of the electromagnetic proportional flow control valve 5 is determined by the predetermined switching time Δt ₁ of the electromagnetic switching valve 3
The electromagnetic switching valve 3 is activated from the beginning, and is configured to switch when the electromagnetic proportional control valve 5 reaches a predetermined flow rate.

In this way, _the pressure program control is performed in the same manner after the third, and as _shown in _FIG . By switching alternately, it is possible to realize multi-stage flow control as shown in FIG. 2(1) without being affected by the delay in the sprue operation time of the electromagnetic proportional flow control valves 4 and 5.

<Effects> Since the multi-stage flow control device 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 proportional flow control valve, and the speed of response of the servo valve can be improved. There is no need to use such expensive valves.

In the above-mentioned embodiment, the set flow rate of each electromagnetic proportional flow control valve is set to 4 stages, resulting in an 8-stage flow rate program, but of course, the present invention is not limited to this, and an arbitrary number of multi-stage flow rate 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 flow rate control situation in the embodiment shown in FIG. 3...Solenoid directional switching valve, 4, 5...Solenoid proportional flow control valve, 7...Signal switch A, 10...Signal switch B, 11...Signal switch C, 12...Signal switch D , 14, 15...Pressure setting device.

Claims (1)

[Claims] 1. In order to control the flow rate of hydraulic oil supplied to any actuator, a pair of electromagnetic proportional flow control valves arranged in parallel in the inflow circuit to the operating side oil chamber of the actuator, and an identical pair of electromagnetic proportional flow control valves. an electromagnetic directional switching valve that switches to one of the same flow rate control valves in order to use one of them, and a large number of flow values for controlling each of the pair of electromagnetic proportional flow control valves in a multistage program. a flow rate setting device to be set, and signal switching devices C and D connected to respective solenoids of the pair of electromagnetic proportional flow control valves, which select one from a large number of flow rate values set in the flow rate setting device. 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 flow rate program control.
and signal switchers C and D from said switcher B.
After a switching signal is transmitted, the desired flow rate program is controlled by a flow rate control device of a hydraulic circuit comprising a signal switching device A that is activated after a predetermined period of time has elapsed to control the electromagnetic directional switching valve. At a predetermined time before the start, the - side of the pair of electromagnetic proportional flow control valves is operated at a predetermined flow rate, and after the predetermined time has elapsed, the program control is operated at the - side of the electromagnetic proportional flow control valve on the - side. When switching the set flow rate after starting flow rate program control, if the - side electromagnetic proportional flow control valve is selected, the other side electromagnetic proportional flow control valve is switched a predetermined time before the same valve is selected. A multistage flow control method characterized by operating the flow at the next set flow value in advance.