JPH05340406A - Solenoid-operated directional flow control valve - Google Patents

Abstract

PURPOSE:To quicken the extent of responsiveness as well as to lessen an amount of return flow rate by installing a variable throttle in a centering piston impulse part and a fixed throttle in a first oil chamber drain passage, respectively, and feeding this first oil chamber with the output pressure via the variable throttle. CONSTITUTION:When an electric current flowing into a proportional solenoid 11 is zero, its action force against a pilot piston 4 is brought to nothing, whereby output pressure Px is added to a first oil chamber 21 of a centering piston 5 by way of a variable throttle Rv, and this first oil chamber 21 is interconnected to a drain passage Dr3 via a fixed throttle Rc1, thereby moving the pilot piston 4 to the right, thus the centering piston 5 is displaced to the left. When this centering piston 5 gets closing the variable throttle Rv, pressure in the first oil chamber 21 goes down, so it is positioned in balance with a spring 7. At the time of resetting the current to being zero, an amount of pilot oil quantity to a drain gets off with smallness. In addition, the variable throttle Rv is large in its opening till the centering piston 5 is returned to neutral, thus a large quantity of pilot oil flows into the first oil chamber 21. Therefore a speed in response is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proportional electromagnetic directional flow control valve.

[0002]

2. Description of the Related Art The structure of a conventional proportional electromagnetic type directional flow control valve of this type is shown in FIG.

In FIG. 8, 1 is a pilot pressure control valve, 2 is a pilot spool, 3 is a spring, 4 is a pilot piston, 5 is a centering piston, 6 is a flapper, 7 is a spring, 8 is a main spool, 9 is a body, Reference numeral 11 is a proportional solenoid, and 12 is a nozzle. 21
Is a first oil chamber of the centering piston 5, and 22 is a second oil chamber. b is a flow path, Rc1 is a fixed throttle, and Dr3 is a drain port. The fixed throttle Rc1 is provided in the middle of the flow path b that connects the pilot pressure control valve 1 and the first oil chamber 21 of the centering piston 5.

In the conventional apparatus having such a structure, the pilot oil flows into the first oil chamber 21 of the centering piston 5 via the fixed throttle Rc1. The pressure in the first oil chamber 21 is
The return fluid is returned to the tank from the drain port Dr3 with a pressure commensurate with the force of the spring 7 and the ejection reaction force of the nozzle 12.

[0005]

However, in such a conventional proportional electromagnetic type directional flow control valve, the speed at which the main spool 8 returns to the neutral position when the input current of the proportional solenoid 11 is turned off. Become slow. Moreover, the positioning accuracy of the main spool 8 is poor. Furthermore, when the pressure of the pilot oil is high, the return flow rate to the tank increases.

That is, the flow rate of the centering piston 5 into the first oil chamber 21 flows through the fixed throttle Rc1. Therefore, the response speed cannot be increased beyond a certain level. Further, although the pressure of the first oil chamber 21 of the centering piston 5 is constant, the pilot oil enters through the fixed throttle Rc1, so that the flow rate changes depending on the pressure of the pilot oil. Although it returns to the tank through the gap between the centering piston 5 and the land, the position of the main spool 8 also changes due to the pressure of the pilot oil because the gap varies depending on the flow rate. Further, when the pressure of the pilot oil is high, there is a problem that the flow rate increases and the efficiency is low.

The present invention has been made in order to solve the above problems of the conventional device, and prevents the pilot oil from entering the oil chamber of the centering piston through the fixed throttle. That is, a proportional solenoid type directional flow control valve with a fast response and a small return flow rate is provided by providing an input port that constitutes a variable orifice with a slit of a centering piston and a body land and returning the return fluid to a tank through a fixed throttle. That is the purpose.

[0008]

According to the present invention, in an electromagnetic directional flow control valve, a variable throttle is formed in a sliding portion of a centering piston, and a fixed throttle is provided in a drain passage of a first oil chamber. The electromagnetic directional flow control valve is configured to supply the output pressure Px to the first oil chamber via the variable throttle. Further, a variable throttle is formed in the sliding portion of the centering piston on the second oil chamber side, and a fixed throttle is provided in the drain passage,
An electromagnetic directional flow control valve for supplying pilot oil to the second oil chamber by an external switching valve via a variable throttle is configured.

Further, in the electromagnetic type directional flow control valve, a variable throttle is formed in the sliding portion of the centering piston, and a fixed throttle is provided in the drain passage of the first oil chamber so that an external switching is performed via the variable throttle. The valve constitutes an electromagnetic directional flow control valve that supplies pilot oil to the first oil chamber by means of a valve. Further, a variable throttle is formed in the sliding portion of the centering piston on the second oil chamber side, and a fixed throttle is provided in the drain passage, and pilot oil is supplied to the second oil chamber by an external switching valve via the variable throttle. The electromagnetic directional flow control valve is configured.

[0010]

The variable throttle made by the slit of the centering piston and the body land has a very large opening until the centering piston returns to the neutral position. Therefore, since a large amount of pilot oil flows into the oil chamber of the centering piston, the response speed is very fast. On the other hand, when the centering piston returns to the neutral position, the oil chamber of the centering piston has a low pressure, and the return flow rate is extremely small. Therefore, the gap formed by the slit of the centering piston and the body land becomes extremely narrow, and the amount of drift when the pressure of the pilot oil changes can be ignored.

[0011]

【Example】

Embodiment 1 FIG. 1 is a configuration explanatory view of Embodiment 1 of the present invention, and FIGS. 2 and 3 are operation explanatory diagrams of Embodiment 1 of the present invention. In each of the drawings of the embodiments of the present invention, the same reference numerals are given to the same parts as some conventional devices.

1 to 3, reference numeral 1 denotes a pilot pressure control valve, and a pressure reducing valve is used here. Reference numeral 2 is a pilot spool of the pilot pressure control valve 1, and 3 is a spring. 4 is a pilot piston, 5 is a centering piston, 7 is a spring, 8 is a main spool, 9 is a body, 11 is a proportional solenoid, 12 is a nozzle, 12a is an internal flow path of the nozzle 12, 15 is a back pressure chamber, 16 is a nozzle. It is a room. Further, 21 and 22 are a first oil chamber and a second oil chamber of the centering piston, and 23 is a fluid chamber provided on the left side of the main spool 8. The proportional solenoid 11 displaces the pilot spool 2 to which the spring pressure of the spring 3 is applied by the input current. And the pilot pressure control valve 1
A pilot oil supply pressure Pp is introduced into the valve to supply an output pressure Pc almost proportional to the input current of the proportional solenoid 11 and an on / off output pressure Px to the pilot piston 5 side.

Reference numeral 5a is a rod of the centering piston 5, and a flapper 6 is fixed to the tip exposed in the nozzle chamber 21. The flapper 6 faces the nozzle 12 in the nozzle chamber 16 via the nozzle gap X. Reference numeral 5b is a sliding hole for the centering piston, and 5c is a body land formed in the sliding hole 5b. Further, 5d is a ring-shaped slit provided on the outer periphery of the centering piston, and 5e is a communicating passage formed in the axial direction. The sliding hole 5b and the body land 5c constitute a variable throttle Rv, and the variable throttle Rv controls the inflow rate of the pilot oil which flows into the first oil chamber 21 upon receiving the output pressure Px of the pilot pressure control valve 1. .. Dr1 to Dr4 are drain passages provided in the body 1, Rc1 and Rc2 are fixed throttles, a, b and c are pilot oil passages, and A, B, P and T are main circuit fluid input / output ports. ..

The pilot oil flowing from the flow path c is directly supplied to the fluid chamber 23 and flows into the back pressure chamber 15 via the fixed throttle Rc2. The pilot oil supplied to the back pressure chamber 15 is ejected from the nozzle 12 through the internal flow path 12a. When the flapper 6 facing the nozzle 12 moves, the nozzle back pressure changes according to the size of the nozzle gap X, and the changed nozzle back pressure is returned to the back pressure chamber 15 to integrate the main spool 8 with the displacement of the flapper 5a. To follow. When the main spool 8 has an intermediate value of the input current of the proportional solenoid 11,
It is held in the centering position shown. The main spool 8 slides left and right in the body 9 around the centering position to alternately switch the input / output ports A, B, P, T so that the flow rate of the main circuit fluid is controlled. It has become.

The operation of the present invention having the above construction will be described below. Since the spring 3 opposes the thrust of the proportional solenoid 11 of the pilot pressure control valve 1 of FIG.
The output pressure Pc is 0 when the input current is 30% or less. At this time, the second oil chambers 2 on both the left and right sides of the centering piston 5
2 and the first oil chamber 21 are connected to the drain and no pressure is applied. When the input current of the proportional solenoid 11 is set to 0%,
The pilot spool 2 is set to the reset position by the spring 3, and the output pressure Px passes through the flow path b to the first oil chamber 2
1, and acts on the centering piston 5.

The state shown in FIG. 1 is when the input current of the proportional solenoid 11 is 65%, and the output pressure Pc sent to the flow path a is 50% of the maximum control output pressure Pc. At this time, the first oil chamber 21 and the second oil chamber 22 on both sides of the centering piston 5 communicate with the drain. The main force applied to the pilot piston 4 and the centering piston 5 is the reaction force of the spring 7. The reaction force due to the ejection of the nozzle 12 is extremely smaller than the force of the pilot piston 4.

The state of FIG. 2 is when the input current of the proportional solenoid 11 is 30% and the output pressure Pc is 0, and the pilot piston 4 is fully moved to the right by the spring 7. Therefore, the main spool 8 is also displaced to the maximum along with the movement of the centering piston 5, following the right side.
At this time, the second oil chamber 22 and the first oil chamber 21 of the centering piston 5 communicate with the drain. Further, when the input current of the proportional solenoid 11 is set to 100%, the output pressure Pc becomes the maximum control pressure, and the pilot piston 4 is moved to the left to the full. Therefore, the main spool 8 also follows the nozzle 12 of the centering piston 5 and is maximally displaced to the left.

In FIG. 3, the input current of the proportional solenoid 11 is 0.
In this state, the acting force on the pilot piston 4 disappears as in the case of FIG. Then, in the first oil chamber 21 of the centering piston 5, the output pressure Px from the flow path b is
(= Pp) is the aforementioned body land 5c and slit 5d
Is added via a variable aperture Rv composed of Also,
The first oil chamber 21 has a drain passage D through a fixed throttle Rc1.
It communicates with r3. Therefore, as compared with the case of FIG. 2, the pilot piston 4 is moved to the right and the centering piston 5 is displaced to the left. When the centering piston 5 starts to close the variable throttle Rv, the pressure in the first oil chamber 21 decreases, and the centering piston 5 is equilibrium stopped and positioned at a position having a force relationship corresponding to the elastic force of the sprinkle 7.

At the time of resetting when the input current of the proportional solenoid 11 is set to 0, the flow rate of the pilot oil flowing from the centering piston 5 to the drain is very small.
That is, the drain flow rate of the pilot oil at this time is determined by the fixed throttle Rc1 and the internal pressure of the first oil chamber 21, but the pressure in the first oil chamber 21 is small and the effective sectional area of the fixed throttle Rc1 can be selected to be sufficiently small. .. Moreover, the positioning of the centering piston 5 is extremely stable. That is, even if the pressure of the pilot oil increases, the flow rate does not change. This means that the pressure in the first oil chamber 21 is constant, and in relation to the fixed throttle Rc1,
This is because the flow rate is decided. Further, the variable throttle Rv has a large opening degree until the centering piston 5 returns to a substantially neutral position, and the first oil chamber 21 of the centering piston 5 is opened.
A large amount of pilot oil flows into the. Therefore, the response speed becomes extremely high.

FIG. 4 is an explanatory diagram of the configuration of the second embodiment. Figure 4
In the second embodiment, the second oil chamber 22 of the centering piston 5 is
A body land 5c2, a slit 5d2 and a communication passage 5e2 as shown in FIGS. 1 to 3 are also formed on the side. And the second
Body land 5c2 and slit 5 provided on the oil chamber 22 side
The variable aperture Rv2 is formed by d2 here as well.
Reference numeral 30 is a hydraulic power source such as a hydraulic pump, and 31 is a cam type switching valve provided outside. The outflow port of the cam type switching valve 31 communicates with the second oil chamber 22 via the variable throttle Rv2. In the cam type switching valve 31 of the second embodiment, a function of closing the control from the P port to the A port direction is added. When the cam type switching valve 31 provided outside of FIG. 4 is not operated, the same operation as in FIG. 1 is performed.

Generally, in the injection molding machine, the mold closing operation is stopped for safety reasons when the operation door is opened. Example 2
When applied to the hydraulic system of the injection molding machine, the cam type switching valve 31 is in the illustrated state when the operation door of the injection molding machine is closed. The electromagnetic directional flow control valve then performs its normal operation. When the mold is released by the operation from the P port to the B port and then the operation door is opened when the mold is closed by the operation from the P port to the A port, the cam type switching valve 31 is switched. Therefore, the pilot oil of the hydraulic power source 30 is supplied to the second oil chamber 22 on the left side of the centering piston 5. When the centering piston 5 is displaced by the supplied parrot fluid and the variable throttle Rv2 is closed, the pressure in the first oil chamber 21 is reduced and the centering piston 5 is positioned at the neutral position.

FIG. 5 shows a third embodiment of the present invention. Unlike the first embodiment shown in FIGS. 1 to 3, the pilot spool 2 is not provided with a land for generating the output pressure Px supplied to the centering piston 5 when the input current of the proportional solenoid 11 is zero. Further, the variable throttle Rv is connected to an electromagnetic switching valve 32 provided outside by a flow path b. And, normally, it is in the state shown. That is, in the third embodiment, when the input current is not 0 and the centering piston 5 is operating in the right direction, the electromagnetic directional control valve 32 is switched at appropriate times to center the electromagnetic directional flow control valve. It is configured.

FIG. 6 is a diagram showing the construction of the fourth embodiment of the present invention. In addition to the third embodiment described with reference to FIG. 5, a cam type switching valve 31 is further provided on the second oil chamber 22 side. As shown, the cam type switching valve 31 may be supplied with hydraulic pressure from another hydraulic source 33, or the hydraulic source 30 for the electromagnetic switching valve 32 on the right side may be commonly used. In the embodiment of FIG.
As compared with FIG. 5, pilot oil is supplied to the second oil chamber 22 and the first oil chamber 21 from the outside through the cam type switching valve 31 and the electromagnetic type switching valve 32. An external cam type switching valve 31 has a function of closing the control from the P port to the A port direction.

When the fourth embodiment is applied to the injection molding machine as described above, when the operation door is closed, the cam type switching valve 31 is in the state shown in the figure and the proportional electromagnetic directional flow control valve operates normally. do. Now, when the operation door is opened when the mold is released by the operation from the P port to the A port and then the operation is changed from the P port to the B port, the cam type switching valve 31 is switched when the operation door is opened. Pilot oil flows into the second oil chamber 22. When the centering piston 5 moves to the right by the pilot oil flowing into the second oil chamber 22 and the variable throttle Rv2 begins to close, the pressure in the second oil chamber 22 decreases and the centering piston 5 is positioned.

A fifth embodiment is shown in FIG. FIG. 7 shows another embodiment of the present invention, in which the internal flow path 2a (FIG. 1) of the pilot spool 2 shown by broken lines in each of FIGS. 1 to 6 is omitted. Then, the spool 2 has inclined surfaces 2 on both shoulders.
The symmetrical land forming b is used. That is,
In the drawing of the fifth embodiment, an electromagnetic directional flow control valve using a positioning type pilot pressure control valve is constructed.

[0026]

According to the present invention, the variable throttle is formed in the sliding portion of the centering piston, and the fixed throttle is provided in the drain passage of the first oil chamber to output the output pressure Px through the variable throttle. An electromagnetic directional flow control valve for supplying the chamber was constructed.
Further, a variable throttle is formed in the sliding portion of the centering piston on the second oil chamber side, and a fixed throttle is provided in the drain passage, and pilot oil is supplied to the second oil chamber by an external switching valve via the variable throttle. An electromagnetic directional flow control valve was constructed.

Further, according to the present invention, the variable throttle is formed in the sliding portion of the centering piston, the fixed throttle is provided in the drain passage of the first oil chamber, and the pilot oil is provided by the external switching valve via the variable throttle. An electromagnetic directional flow control valve for supplying the oil to the first oil chamber was constructed. Further, a variable throttle is formed in the sliding portion of the centering piston on the second oil chamber side, and a fixed throttle is provided in the drain passage, and pilot oil is supplied to the second oil chamber by an external switching valve via the variable throttle. An electromagnetic directional flow control valve was constructed.

As a result, since the pilot oil flows into the first oil chamber of the centering piston via the variable throttle, the response speed can be increased. Further, since the return fluid of the first oil chamber of the centering piston is returned to the tank via the fixed throttle, the passing flow rate is reduced and the efficiency is improved. Therefore, according to the present invention, it is possible to provide a proportional electromagnetic directional flow control valve having a fast response and a small return flow rate.

[Brief description of drawings]

FIG. 1 is a configuration explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 3 is another operation explanatory diagram of the first embodiment of the present invention.

FIG. 4 is a structural explanatory diagram of Embodiment 2 of the present invention.

FIG. 5 is a configuration explanatory diagram of a third embodiment of the present invention.

FIG. 6 is a structural explanatory diagram of Embodiment 4 of the present invention.

FIG. 7 is a diagram illustrating the configuration of the fifth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a configuration of a conventional device.

[Explanation of symbols]

 1 Pilot Pressure Control Valve 2 Pilot Spool 3 Spring 4 Pilot Piston 5 Centering Piston 6 Flapper 7 Spring 8 Main Spool 9 Body 11 Proportional Solenoid 12 Nozzle 21 First Oil Chamber 22 Second Oil Chamber 31 Cam Type Switching Valve 32 Electromagnetic Switching Valve Pp Supply pressure Px Output pressure Pc Output pressure Rc1, Rc2 Fixed throttle Rv, Rv1, Rv2 Variable throttle Dr1 ~ Dr4 Drain flow channel a, b, c Flow channel A, B, P, T I / O port

Claims (4)

[Claims] 1. A pilot pressure control valve for displacing a pilot spool by an input current of a solenoid to output output pressures Pc and Px, a pilot piston displacing corresponding to the output pressure Pc of the pilot pressure control valve, A centering piston that slides between a first oil chamber opposite to the pilot piston side and a second oil chamber formed at the other end and has a flapper extending toward the second oil chamber, and a flapper of the centering piston. An electromagnetic directional flow control valve, comprising: a main spool connected to a nozzle opposed to the main spool, the main spool switching the input / output port of the main circuit fluid by displacing the flapper left and right around a centering position. A variable throttle is formed in the sliding portion of the centering piston, and a fixed throttle is provided in the drain passage of the first oil chamber to adjust the output pressure Px. An electromagnetic directional flow control valve, characterized in that it is supplied to the first oil chamber via the. 2. A variable throttle is formed in a sliding portion of the centering piston on the second oil chamber side, and a fixed throttle is provided in a drain passage, and a second valve is provided by an external switching valve via the variable throttle.
The electromagnetic directional flow control valve according to claim 1, wherein pilot oil is supplied to the oil chamber. 3. A pilot pressure control valve that displaces a pilot spool by an input current of a solenoid to output an output pressure Pc, a pilot piston that displaces in response to an output pressure Pc of the pilot pressure control valve, and the pilot piston. Side centering piston that slides between a first oil chamber and a second oil chamber formed on the other end side, and a flapper extends toward the second oil chamber side, and a centering piston facing the flapper of the centering piston. An electromagnetic directional flow control valve having a main spool which is connected to a nozzle and which shifts left and right around a centering position following the displacement of the flapper to switch the input and output ports of the main circuit fluid. A variable throttle is formed on the sliding portion of the first oil chamber, and a fixed throttle is provided in the drain passage of the first oil chamber so that an external switching can be performed via the variable throttle. Electromagnetic directional flow control valve and supplying the pilot oil in the first oil chamber through. 4. A variable throttle is formed in a sliding portion of the centering piston on the second oil chamber side, and a fixed throttle is provided in a drain passage, and a second valve is provided by an external switching valve via the variable throttle.
The electromagnetic directional flow control valve according to claim 3, wherein pilot oil is supplied to the oil chamber.