JPH0443603Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a fluid control valve used where electrohydraulic servo valves, digital control valves, high-speed solenoid valves, proportional solenoid control valves, etc. are used.

(Prior art) In recent years, electro-hydraulic servo valves have already been put into practical use to achieve electrical control of hydraulic machinery, automation through electronic control, energy saving, and ease of operation. Therefore, pulse motor type and high speed solenoid valve type digital servo valves have appeared.

(Problem to be solved by the invention) These electro-hydraulic servo valves and digital servo valves are used in various fields depending on their characteristics, but they all control the back pressure of the spool continuously and almost comparatively. Since this process changes steplessly, various problems arise when used in harsh environments such as construction, civil engineering, agricultural machinery, etc., as described below.

It has a complex structure, has a large number of parts, and requires high precision, making it expensive and lacking in reliability.

In adverse environments, it is difficult to ensure contamination resistance of NASIO grade or lower, and if you use filters, etc., the cost will increase.

Under adverse environments, it is difficult to maintain and handle the product to keep it clean at all times.

(Means for Solving the Problems) In view of the above, the present invention aims to provide a highly practical and inexpensive fluid by changing the back pressure of the spool intermittently and stepwise. The purpose of the present invention is to provide a control valve, the gist of which is to move a spool, which is fitted in a cavity of a valve body so that it can slide in a liquid-tight manner in the left and right directions, toward a central neutral position by means of a neutral spring. At the same time, the control pressure chambers through which the pilot fluid flows in and out of the left and right ends of the spool are limited, and the pressure and inflow and outflow speed of the pilot fluid in each control pressure chamber are changed to change the displacement of the spool and its direction and speed. In the fluid control valve that switches and controls the flow direction and flow rate of the working fluid by changing the flow rate, an electromagnetic switching valve that operates in two positions to open and close in response to an electric input signal is provided in the pilot fluid inlet or outlet passage of each control pressure chamber. A plurality of electromagnetic switching valves are installed in parallel with each other and have different flow resistances on the upstream or downstream side of the electromagnetic switching valve and operate in two positions, sequentially or simultaneously in response to an electrical input signal. The feature lies in the fluid control valve.

(Function) Since the present invention has the above configuration, each electromagnetic switching valve is opened and closed in response to an electrical input signal, and a plurality of electromagnetic switching valves are sequentially or simultaneously opened and closed to control the pressure of the pilot fluid in the control pressure chamber. The displacement, direction and speed of the spool are controlled by changing the inflow and outflow speed intermittently and stepwise, thereby switching and controlling the flow direction and flow rate of the working fluid.

(Example) Hereinafter, the present invention will be specifically described with reference to illustrated embodiments.

In FIGS. 1 and 2, 1 is a valve main body, 2 is a spool fitted in a cavity 1a of the valve main body 1 so as to be slidable in a liquid-tight manner in the left and right direction, and lands 3 are provided at the center and both ends of the spool, respectively. It has 4 and 5. land 4
The right end surface of the land 5 cooperates with the inner wall surface of the cavity 1a to limit the right control pressure _S1 , and similarly, the left end surface of the land 5 cooperates with the inner wall surface of the cavity 1a.
It cooperates with the inner wall surface of a to limit the left control pressure chamber _S2 . A neutral spring 6 is fitted in the right control pressure chamber _S1 , and a neutral spring 7 is fitted in the left control pressure chamber _S2 , and these neutral springs 6 and 7 move the spool 2 to the central neutral position. is being energized towards.

In the illustrated neutral position, the working fluid, that is, pressure oil, discharged from the main pump 8 enters the valve body 1 from the pump port _P1 , but the pressure oil flow path is connected to the land 3 in the center of the spool 2. Then it gets blocked. When the spool 2 is moved to the right in the figure, the pressure oil that entered the valve body ₁ from the pump port P1 is supplied to the head side chamber 9a of the actuator 9 from the port _C1 , and the oil in the rod side chamber 9b is It enters the valve body 1 from _C2 and returns to the tank ₁₀ via tank port T1. Conversely, when spool 2 is moved to the left, pressure oil flows to the port.
The oil in the rod side chamber 9b of the actuator 9 is supplied from _C2 , and the oil in the head side chamber 9a returns to the tank ₁₀ from port _C1 via tank port T1.

On the other hand, the pilot oil discharged from the pilot pump 11 enters the valve body 1 from the pump port _P2 , and a part of it passes through the pilot supply passage 13 in which the fixed throttle 12 is interposed, and enters the right control pressure chamber _S1. The remainder is supplied into the left control pressure chamber _S2 through a pilot supply passage 15 in which a fixed throttle 14 is interposed.

The pilot oil flowing out from the right control pressure chamber _S1 passes through the electromagnetic switching valve X installed in the pilot outflow passage 16, and then passes through the solenoid switching valve
Tank port via four solenoid valves A, B, and C.
Return to tank 17 from T ₂ . The pilot oil released from the left side control pressure _S2 flows through the pilot outflow passage 18.
The three electromagnetic switching valves A, B, and
C and returns to tank 17 from tank port _T2 .

The electromagnetic switching valves X, Y and the electromagnetic switching valves A, B, C are each fastened to the valve body 1 with bolts 19,
Each has the same structure and operates in two positions: open and close. The electromagnetic on-off valves A, B, and C have flow resistances ζ _A , ζ _B , and ζ _C that are different from each other, and the magnitude of each flow resistance is ζ _A
＞ζ _B ＞ζ _C.

The electromagnetic switching valve
2 moves to the left against the elastic force of the return spring 23, and the push rod 24 fixed to its tip moves the spherical valve 25 to the left against the spring 26 to open the valve. When the user leaves the seat, this electromagnetic switching valve X is opened. When the energization to the coil 21 is stopped, the spherical valve 25 is pushed by the presser spring 26 and seats on the valve seat, and the electromagnetic switching valve X is closed.

A schematic circuit diagram of the pilot oil is shown in FIG.

When all of the electromagnetic switching valves X, Y and electromagnetic switching valves A, B, and C are fully closed, the control pressures P _c1 and P _c2 in the right control pressure chamber S ₁ and left control pressure chamber S ₂ are controlled by the pilot pump 11. The discharge pressure Po of these electromagnetic switching valves X, Y and electromagnetic switching valves A, B, C
by selectively opening and closing sequentially or simultaneously.
Differential pressure between P _c1 and P _c2 , that is, control pressure difference | P _c1 − P _c2
There are 15 ways of | as shown in Figure 3.

That is _, when the _solenoid switching valve Since it flows out through valve A, the pressure in chamber _S1 decreases by an amount corresponding to this flow resistance, and the control pressure in chamber _S1 becomes _Pc11 . Therefore, spool 2 is connected to Po.
It moves to a position where the force obtained by multiplying the differential pressure with P _c11 , that is, the control pressure difference |Po−P _c11 | by the pressure receiving area of the spool 2, is balanced with the reaction force of the neutral springs 6 and 7, and stops.
The same applies when other electromagnetic switching valves or electromagnetic shut-off valves are opened or closed.

Now, as shown in FIG. 4, when the operating lever 31 of the rotation transmitter, for example, the rotation potentiometer 30, is swung by an angle θ in the direction of the arrow, the controller 32 applies a voltage corresponding to this angle θ to the fluid control valve 1. Output.

When the voltage output from the controller 32 is positive, as shown in FIG. 5, X is ON, but Y
becomes OFF. Then, when the voltage is about +1/7V, A is
ON, B and C are OFF, B is ON at +2/7V,
A and C are OFF, C is ON at +3/7V, and A and B are
At +4/7V, A and B are ON and C is OFF. At +5/7V, A and C are ON and B is OFF.
At +6/7V, B and C are ON, A is OFF, and +7/7
At V, A, B, and C are all turned on.

When the voltage output from the controller 32 is negative, Y is ON and X is OFF, and the voltage is approximately -1/
At 7V, A is ON and B and C are OFF, and from then on, A, B and C are turned OFF depending on the voltage, as when the voltage is positive.
B and C are turned on and off.

Then, the electromagnetic switching valves X, Y and the electromagnetic switching valve A,
When B and C are turned on and off as described above, the force acting on spool 2, that is, the control pressure difference acting on control pressure chambers _S1 and _S2 , changes stepwise as shown in Figure 6. Furthermore, the displacement speed of the spool 2 changes as shown in FIG. That is, when the solenoid switching valve X and the solenoid switching valve A are ON, the displacement speed of the spool 2 is V ₁
If a gradient θ ₁ is drawn, and X and B are ON, the displacement speed is V ₂
Draw a slope θ ₂ . Similarly, the gradients θ ₃ , θ ₄ , θ ₅ ,
Draw θ ₆ and θ ₇ .

Since the change in port area due to the displacement of the spool 2 can be selected in various ways as shown in FIG. By sequentially or simultaneously opening and closing the electromagnetic on-off valves A, B, and C in a predetermined order, this fluid control valve 1
The responsiveness of the system can be improved to a level that does not pose a problem for practical use.

In addition, in the above embodiment, the control pressure chambers S ₁ ,
Although the pilot outflow passages 16 and 18 of S ₂ are equipped with electromagnetic switching valves X and Y, and the electromagnetic switching valves A, B and C are installed downstream thereof in two stages, the pilot supply passages 13 of control pressure chambers S ₁ and S ₂ , 15, and three or more electromagnetic on-off valves can be connected in parallel.

(Effects of the invention) In the present invention, an electromagnetic switching valve is installed in the pilot fluid inflow path or outflow path of each control pressure chamber, and the electromagnetic switching valve can be operated in two positions by an electric input signal. A plurality of electromagnetic switching valves are installed in parallel on the downstream side, which have different flow resistances and operate in two positions sequentially or simultaneously depending on the electrical input signal. The displacement of the spool as well as its direction and speed are controlled by changing the pressure and inflow/outflow speed of the pilot fluid in the control pressure chamber intermittently and stepwise by sequentially or simultaneously opening and closing a plurality of electromagnetic on-off valves. The flow direction and flow rate of the working fluid can be switched and controlled within a range that does not cause any control problems. Since the electromagnetic switching valve and the electromagnetic on-off valve only need to operate in two positions: open and close, they have a simple structure and low cost, and are easy to operate and handle even in adverse environments, and are highly reliable.
A fluid control valve with a long life can be obtained.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a system diagram partially shown in cross section, Fig. 2 is a schematic circuit diagram of the pilot fluid, and Fig. 3 shows the opening and closing of the electromagnetic switching valve and the electromagnetic shut-off valve. A diagram showing the relationship between and control pressure,
Figure 4 is a control system diagram, Figure 5 is a diagram showing the relationship between electrical input and operating points of the electromagnetic switching valve and electromagnetic switching valve, and Figure 6 is the opening/closing of the electromagnetic switching valve and electromagnetic switching valve and the control pressure difference. FIG. 7 is a diagram showing the change in spool speed, and FIG. 8 is a diagram showing the relationship between spool displacement and port area. Spool...2, Control pressure chamber... _S1 , _S2 , Solenoid switching valve...X, Y, Solenoid on/off valve...A, B, C, Pilot supply passage...13, 15, Pilot outflow passage... 16,18.

Claims (1)

[Scope of utility model registration request] Control pressure that forces a spool, which is slidably slidably liquid-tight in the left and right directions in the cavity of the valve body, toward the central neutral position by a neutral spring, and that pilot fluid flows in and out of the left and right ends of the spool, respectively. A fluid control valve that limits a chamber and switches and controls the flow direction and flow rate of the working fluid by changing the pressure and inflow/outflow speed of the pilot fluid in each of the control pressure chambers to change the displacement of the spool and its direction and speed. In this method, an electromagnetic switching valve that operates in two positions, open and close, according to an electric input signal is installed in the pilot fluid inflow path or outflow path of each of the control pressure chambers, and different flow resistances are installed on the upstream side or downstream side of the electromagnetic switching valve. 1. A fluid control valve characterized in that a plurality of electromagnetic on-off valves are disposed in parallel with each other and are operated in two positions sequentially or simultaneously in response to an electric input signal.