JPH0247336Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a directional control valve, and more particularly to a directional control valve in which a valve seat is opened and closed by an electrostrictive element.

[Prior Art] Directional switching valves that utilize the property of a laminated electrostrictive element to expand and contract when energized to open and close a valve seat with a valve member provided on the electrostrictive element include, for example,
This is known from Japanese Patent Application Laid-open No. 111226/1983.

However, in the above-mentioned directional control valve, the electrostrictive element is exposed inside the valve chamber, so when using a conductive fluid or a gas containing moisture as the pressure fluid, it is necessary to There were drawbacks such as a decrease in the insulation resistance between the two, leading to a decrease in the functionality of the electrostrictive element and the risk of damaging control equipment.

In addition, in a directional valve using such a laminated electrostrictive element, the acting force accompanying the expansion and contraction of the electrostrictive element is extremely large, so the valve member may be pressed against the valve seat with excessive force. This also has the disadvantage that the valve member is easily worn out.

[Problems to be solved by the invention] The problem of the invention is to solve the above-mentioned drawbacks of the conventional directional control valve all at once, and to provide good insulation even when the pressure fluid is a conductive fluid or a gas containing moisture. To provide a directional control valve which can maintain the properties of the valve member, prevent the valve member from being pressed against the valve seat with excessive force by an electrostrictive element, and prevent wear and tear of the valve member. be.

[Means for Solving the Problems] In order to solve the above problems, the directional control valve of the present invention has a first valve seat between the first port and the second port, and a seat between the second port and the third port. The second valve seats between the two valve seats are formed so as to face each other, and the first valve seat opens the first valve seat.
A first valve member biased in the valve closing direction by a return spring is disposed in the valve chamber, and the end portion is placed in the second valve chamber in which the second valve seat opens and communicates with the first valve chamber. and is attached to the tip of the electrostrictive element,
A second valve member that also serves as an insulating seal member that can expand and contract according to the expansion and contraction of the electrostrictive element is disposed, and a push rod is provided between these two valve members for opening and closing the first valve member by the electrostrictive element. is installed so as to be in constant contact with both valve members, and when the first valve member is closed, the push rod is caused to bite into the second valve member by the biasing force of the return spring, thereby closing the first valve member. It is characterized by maintaining a degree of elasticity that allows for.

[Operation] When a predetermined voltage is applied to the electrostrictive element, the electrostrictive element expands, and the second valve member attached to it expands and is pressed into contact with the second valve seat, and is also pressed through the push rod. The first valve member is then separated from the first valve seat against the return spring, and the open and closed states of both valve members are switched.

At this time, the contractile force associated with the expansion of the second valve member and the repulsive force associated with the compression of the return spring act as a resistance force against the expansion of the electrostrictive element, so the acting force of the electrostrictive element is reduced, and the The force with which the two valve members abut against the valve seat becomes smaller.

When the application of voltage to the electrostrictive element is released, the electrostrictive element returns to the contracted state, the second valve member contracts to open the second valve seat, and the first valve member releases the return spring. It returns due to the biasing force and closes the first valve seat.

Here, since the tip of the push rod is always in elastic contact with the second valve member, the second valve member does not come into impactive contact with the tip of the push rod every time the electrostrictive element extends. , even with frequent switching, the second
The valve member is less prone to wear and tear. Furthermore, when the first valve member is closed, the tip of the push rod is brought into contact with the second valve member in a biting state due to the urging force of the return spring. This does not prevent the first valve member from closing.

Furthermore, since the surface of the electrostrictive element is covered with the second valve member, good insulation is maintained even if the pressure fluid is a conductive fluid or a gas containing moisture.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, 10 indicates a valve section, and 11 indicates a switching operation section.

Inside the body 12 of the valve portion 10,
A first valve seat 16 located between the first port 13 and the second port 14 and a second valve seat 17 located between the second port 14 and the third port 15 are shaped so as to face each other. The first valve seat 16 is opened and the first valve seat 16 is opened.
Inside the valve chamber 18 is a first valve held by a valve holder 23.
The valve member 21 is connected to the valve holder 23 and the sealing member 24.
The distal end portion of the electrostrictive element 28 is biased in the valve closing direction by a return spring 20 contracted between the electrostrictive element 28 and A cylindrical second plate which also serves as an insulating seal member is attached.
The valve member 22 connects the end of the cylindrical portion 22a to the body 1.
The second valve member 22 is fixed to the cylindrical portion 2 as the electrostrictive element 28 expands and contracts.
The second valve seat 17 is opened and closed while causing expansion and contraction deformation of the valve member 2a.
22, the first valve member 21 is connected by an electrostrictive element 28.
A push rod 26 for opening and closing both the valve chambers 1
It is constructed so as to pass through a through hole 25 that allows the parts 8 and 19 to communicate with each other.

One end of the push rod 26 is integral with the valve holder 23, and the tip is brought into contact with the second valve member 22. The length of the push rod 26 is the same as that of the first valve member 21 shown in FIG. It is formed in such a size that its tip always comes into contact with the second valve member 22 even in the closed state. In this way, the push rod 26 is moved to the second position.
By abutting the valve member 22, the first valve member 2
In order to prevent valve 1 from becoming unable to close, the second
As shown in detail in FIG. 2, the push rod 26 is elastically bitten into the valve member 22 by the biasing force of the return spring 20, and this biting allows the first valve member 21 to close. It maintains a certain degree of elasticity.

Further, the electrostrictive element 28 in the operation section 11
is made by laminating many plate-like materials, and when a voltage of a predetermined polarity is applied, it expands in the axial direction, and when a voltage of the opposite polarity is applied or the voltage application is removed, it returns to the contracted state. It is something to do. This electrostrictive element 28 is attached to an adjustment screw 30 via a pedestal 29, and its position can be adjusted by this adjustment screw 30. This electrostrictive element 2
The second valve member 22 can be attached to the valve member 8 by appropriate means such as coating, adhesion, and fitting.

In the directional control valve having the above configuration, when a predetermined voltage is applied to the electrostrictive element 28, the electrostrictive element 28 expands, and accordingly, the second valve member attached to the electrostrictive element 28 The cylindrical portion 22a of 22 expands and the second valve member 22 comes into pressure contact with the second valve seat, and the first valve member 21 is pushed back by the return spring 2 by the push rod 26.
0 and is pushed down and separated from the first valve seat 16, and the open and closed states of both valve members 21 and 22 are switched.

At this time, the contractile force associated with the expansion of the cylindrical portion 22a and the repulsive force associated with the compression of the return spring 20 act as resistance against the expansion of the electrostrictive element 28, so that the acting force of the electrostrictive element 28 is reduced. and the second valve member 2
The force with which valve 2 contacts the second valve seat 17 becomes smaller.

When the application of voltage to the electrostrictive element 28 is released, the electrostrictive element 28 returns to the contracted state, and the second valve member 2
2 contracts to open the second valve seat 17, and at the same time, the first valve member 21 returns due to the biasing force of the return spring 20 and closes the first valve seat 16.

Here, since the tip of the push rod 26 is always in elastic contact with the second valve member 22, the electrostrictive element 2
The second valve member 22 does not come into shocking contact with the tip of the push rod every time the valve 8 is extended, and the second valve member 22 is less likely to be worn out even if it is frequently switched. Further, when the first valve member 21 is closed, the push rod 2
6 is brought into contact with the second valve member 22 in a biting state due to the biasing force of the return spring 20, so even if the push rod 26 is in contact with the second valve member 22, the first valve member 21 will not be prevented from closing.

Further, the electrostrictive element 28 is connected to the second valve member 22.
Since the surface is coated with , good insulation properties are maintained even if the pressure fluid is a conductive fluid or a gas containing moisture.

[Effects of the invention] As described above, according to the directional control valve of the present invention, the outer surface of the electrostrictive element exposed inside the valve chamber is covered with the second valve member which also serves as an insulating seal member, so that pressure fluid is prevented from leaking. Even if it is a conductive fluid or a gas containing moisture,
The insulation resistance between the electrodes and the ground portion of the electrostrictive element does not decrease, and the function of the electrostrictive element can be maintained for a long time.

Furthermore, when the electrostrictive element is expanded, the contraction force due to the expansion of the second valve member and the repulsive force due to the compression of the return spring are made to act as resistance forces, so that the acting force of the electrostrictive element is reduced. The force with which the second valve member contacts the valve seat can be reduced.

Furthermore, since the tip of the push rod is always brought into elastic contact with the second valve member, the second valve member is prevented from shockingly abutting the tip of the push rod each time the electrostrictive element extends. However, it is possible to reliably prevent the second valve member from being worn out due to frequent switching.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 is an enlarged view of the main parts thereof. 12...Body, 13...1st port, 14...
...Second port, 15...Third port, 16...First valve seat, 17...Second valve seat, 18...First valve chamber,
19...Second valve chamber, 20...Return spring, 21...
First valve member, 22... Second valve member, 5... Through hole,
26... Push rod, 28... Electrostrictive element.

Claims (1)

[Scope of utility model registration request] A first valve seat between the first port and the second port and a second valve seat between the second port and the third port are formed to face each other, and the first valve seat opens to the first valve seat. A first valve member biased in the valve closing direction by a return spring is disposed in the valve chamber, and the end portion is placed in the second valve chamber in which the second valve seat opens and communicates with the first valve chamber. A second valve member, which also serves as an insulating seal member, is fixed to the top of the electrostrictive element and is attached to the tip of the electrostrictive element, and is expandable and deformable according to the expansion and contraction of the electrostrictive element. , a push rod for opening and closing the first valve member by an electrostrictive element is installed so as to be in constant contact with both valve members, and is applied to the second valve member by the biasing force of a return spring when the first valve member is closed. A directional control valve characterized in that the first valve member maintains elasticity to the extent that it causes the push rod to bite and close the first valve member.