JPH0221665Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is an electronic valve that directly opens and closes a valve seat with a valve body provided on an electrostrictive element.
Covering the electrostrictive element with a flexible bag-like body,
This invention relates to an electronic valve that is protected from moisture, oil, sudden temperature changes, etc.

[Prior art]

Electronic valves that use electrostrictive elements to directly open and close valve seats are attracting attention as directional control valves used in pneumatic circuits.

First, the basic configuration of the electronic valve already proposed by the applicant will be explained. FIG. 3 is a sectional view showing the basic structure of the electronic valve, and FIG. 4 is a perspective view showing an example of an electrostrictive element used in the electronic valve.

The valve body 1 has an air space 1 in the center that is open at the top.
00 is formed. In addition, main unit 1 has an import IN, an out port OUT, and an exhaust port EXH.
is provided. Import IN is flow path 10
1 to an annular air space 102. The outport OUT is in direct communication with the air space 100. Exhaust port EXH is flow path 106
It communicates with an annular air space 107 via.

The main body 1 is provided with valve seat members 11 and 12. The valve seat members 11 and 12 have valve seats 11a and 1 at their tips.
It is a cylindrical member having a diameter 2a, and threaded portions 11b and 12b are provided on the outer periphery of the cylinder. The rear ends of the valve seat members 11 and 12 are sealed with fillers 13 and 14, forming air spaces 104 and 109 inside, and the air spaces 104 and 109 communicate with the outer air spaces 102 and 107, respectively. flow path 103,
Flow paths 105 and 110 are provided which communicate with the openings of the valve seats 11a and 12a. Valve seat member 1
1 and 12 are provided with pressing surfaces 11c and 12c for positioning and fixing the permanent magnet 21.

The valve seat members 11, 12 are O-rings 91, 91a,
It is positioned and fixed to the main body 1 via the screw portions 11b, 12b while maintaining airtightness via the screw portions 92, 92a. At this time, the air space 102 communicating with the import IN is connected to the air space 1 of the main body 1 through the flow path 103, air space 104, and flow path 105 of the valve seat member 11.
Connects to 00. Similarly, the air space 107 communicating with the exhaust port EXH is connected to the flow path 10 of the valve seat member 12.
8, main body 1 via air space 109 and flow path 110
It communicates with the air space 100 of. In addition, the valve seat member 1
The 1st and 12th valve seats 11a and 12a are provided facing each other.

As shown in FIG. 4a, the electrostrictive element 3 includes two piezoelectric ceramics 31 and 32 and a metal plate 33 made of different materials.
This is an element with a bimorph structure in which both are bonded together. Silver electrodes are provided on the surfaces of the piezoelectric ceramics 31 and 32 by baking. It is suitable for the piezoelectric ceramics 31 and 32 to have a relatively large piezoelectric coefficient; for example, lead zirconate titanate (PZT) ceramic is used. The metal plate 33 is used as an electrode, and is suitably made of brass, for example. If two electrostrictive elements 3 are stacked on top of each other as shown in Figure 4b, the force due to strain can be reduced by 2.
Can be doubled.

The electrostrictive element 3 is connected to a lead wire 6, and the 2
It is soldered to the front side of the piezoelectric ceramic and the metal plate 33 side. A resistor 7 is connected to the lead wire 6. The upper end of the electrostrictive element 3 and the connection portion between the lead wire 6 and the resistor 7 are integrally molded with a polymeric material 8. This is to prevent accidents such as poor contact and disconnection due to high-speed operation of the electrostrictive element 3, thereby improving the reliability of the valve. The reason why the resistor 7 is inserted is to discharge the electric charge accumulated in the electrostrictive element 3 when the electrostrictive element 3 is made non-conductive, thereby making it easier for the electrostrictive element 3 to return to its original state. The lid 54 is fixed to the main body 1 with screws 55, 55, and the center portion of the lid 54 is sealed with a bush 53. Electrostrictive element 3
Valve bodies 41 and 42 are located at the tips of valve seat members 11 and 12.
The valve seats 11a and 12a are provided facing each other. The element holder 51 seals the air between the upper part of the air space 100 and the outside, and is further completely sealed with the polymer material 8. The element holder 51 is made of an elastic material such as rubber and has a rectangular shape along the electrostrictive element 3, and is fitted into the main body 1. This is to reduce the size of the valve, reduce the capacity of the air space 100, and improve load response.

A guide groove 10 is provided on the lower surface of the air space 100, and a permanent magnet 21 is installed in the guide groove 10.
is placed. The permanent magnet 21 has pressing surfaces 11c, 1 of the valve seat members 11, 12 at the corners of the top surface and both side surfaces.
Slanted surfaces 21a and 21b are provided to be pressed by the main body 2c, and a convex portion 21c that fits into the guide groove 10 of the main body 1 is provided on the lower surface. On the other hand, a permanent magnet 22 is attached to the lower end of the electrostrictive element 3.
The polarities of the permanent magnets 21 and 22 are arranged so as to repel each other. The gap between the two magnets and the strength of the magnetic poles of the permanent magnets are determined so that the force of the permanent magnets 21 and 22 does not exceed the force of the electrostrictive element 3. The permanent magnets 21 and 22 are rubber permanent magnets. The reason why a rubber permanent magnet is used as the permanent magnet 21 is mainly because the pressing surfaces 11c, 1 of the valve seat members 11, 12
This is because since the rubber permanent magnet 21 is clamped and fixed by the rubber permanent magnets 2c, elasticity is required to provide a bending margin and absorb dimensional errors during positioning adjustment. Additionally, if a rubber permanent magnet is used, it will also serve as a rust prevention function. The reason why a rubber permanent magnet is used as the permanent magnet 22 is mainly because it has good adhesion to the electrostrictive element 3 and is easy to attach.

Next, the operation of the embodiment of the electronic valve of the present invention will be explained.

When the lead wire 6 is not energized, the electrostrictive element 3 is not distorted, so the valve body 41 provided on the electrostrictive element 3 closes the valve seat 11a. At this time, the permanent magnet 22 increases the pressing force on the valve seat 11a by the repulsive force and attractive force with the permanent magnet 21. Therefore, from import IN to flow path 101, air space 102, flow path 103, air space 104, flow path 1
Air pressure supplied via 05 is cut off.

If the lead wire 6 is now energized, the electrostrictive element 3 will be distorted to the right. When the permanent magnet 22 reaches a point where it becomes balanced with the permanent magnet 21 due to the distortion of the electrostrictive element 3, the permanent magnet 22 is repelled by the permanent magnet 21, and the distortion of the electrostrictive element 3 and the repulsive force of the permanent magnets 21 and 22 are combined with attraction. Instantly moves to the right due to force. Therefore, the valve body 41 provided on the electrostrictive element 3 opens the valve seat 11a, and the valve body 42 closes the valve seat 12a. Therefore, from import IN to flow path 101 and air space 1
02, flow path 103, air space 104, flow path 105
The air pressure supplied through the air space 10
0 and flows to the outport OUT.

When the power supply to the lead wire 6 is stopped, the electrostrictive element 3 returns to its original state due to its own rigidity. When the permanent magnet 22 passes the point where it balances with the permanent magnet 21 due to the distortion of the electrostrictive element 3, the permanent magnet 22 becomes the permanent magnet 21.
is repelled and attracted by the electrostrictive element 3 and instantaneously moves to the left side due to the rigidity of the electrostrictive element 3 and the repulsive force and attractive force of the permanent magnets 21 and 22. Therefore, the valve body 41 is the valve seat 1.
1a is closed, and the valve body 42 opens the valve seat 12a. Therefore, the air pressure from the outport OUT is exhausted from the exhaust port EXH via the air space 100, flow path 110, air space 109, flow path 108, air space 107, and flow path 106.

[Problems to be solved by the invention] If moisture, oil, dirt, etc. contained in the working fluid adhere to the electrostrictive element used in such electronic valves, the following problems will occur. .

When moisture adheres, insulation resistance decreases,
Consumes more power than necessary when driving. In addition, if moisture seeps into the inside of the ceramic element,
Since the internal electric flux density generated by the applied voltage is lower than when dry, various piezoelectric properties are deteriorated. Furthermore, since the electrodes are made of pure silver, there is a risk of oxidative corrosion. Furthermore, if there is moisture between the silver electrodes and a DC voltage is applied to both ends for a long period of time, silver migration (growth movement phenomenon of silver crystals), which is a phenomenon similar to electrolysis, will occur between the two electrodes. There is a risk of being shot.

If oil is attached, impurities mixed in the oil will cause the same adverse effects as those caused by water. Even in the case of garbage, the garbage absorbs moisture,
There are similar negative effects. If the dust is conductive, such as metal powder, there is a risk of inter-electrode shoots.

Further, when there is a sudden temperature change in the working fluid, it adversely affects the electrostrictive element. In other words,
This is because even if the temperature becomes high, it is necessary to use the piezoelectric body at a temperature below the Kuuri point, and in the case of an actuator, it is desirable to use it at a temperature below 100°C even at high temperatures because of the adhesive layer.

In order to solve these problems, it may be possible to coat the electrostrictive element with a resin, but this has the drawbacks that the degree of freedom against distortion may be inhibited and air sealing is cumbersome.

An object of the present invention is to provide an electronic valve that can protect an electrostrictive element from moisture, oil, or rapid temperature changes.

(Means for Solving the Problems) In order to achieve the above object, the electronic valve according to the present invention has a first port facing the air space, and a second port facing the first valve seat. The second one facing the seat
a valve body having a third port connected to the air space at each valve seat; and a bimorph-structured electric current having a base fixed to the body so that the tip extends beyond the first and second valve seats. a strain element, a water-resistant, oil-resistant, and heat-insulating flexible bag-like body that is placed over the electrostrictive element and sealed at the base;
and first and second valves provided on the electrostrictive element via the bag-like body so as to face the second valve seat.
The valve body is configured to switch the direction of the working fluid by driving the electrostrictive element to open and close the first and second valve seats.

(Example) Hereinafter, the present invention will be explained in more detail with reference to the drawings and the like.

FIG. 1 is a sectional view showing an embodiment of the electronic valve according to the present invention, and FIG. 2 is a perspective view showing an example of a bag-like body used in the electronic valve according to the present invention. Note that the same reference numerals are given to the same parts as in the basic configuration described above.

The electrostrictive element 3 includes a bag-like body 30 as shown in FIG.
covered with.

As shown in FIG.
a, a collar portion 30b, and a rib 30c.

The bag portion 30a is for tightly covering the electrostrictive element 3. The optimal thickness of the bag portion 30a is about 0.3 mm. Note that the valve bodies 41 and 42 may be integrally formed in the bag portion 30a.

The collar portion 30b is for attaching the bag portion 30a to the main body 1.

The rib 30c is provided on the main body 1 side of the collar portion 30b. Two ribs 30c are provided on each side in the longitudinal direction, and one rib is provided on each side in the transverse direction. The reason why the ribs 30c are provided is to prevent slippage with the main body 1 and to maintain airtightness.

The material of the bag-like body 30 may be any flexible material that is water resistant, oil resistant, and has heat insulating properties. In this embodiment, the bag-like body 30 is a rubber bag.

Note that the rubber must not contain sulfur. The reason for this is that the silver electrode of the piezoelectric element combines with sulfur to form silver sulfide. Since silver sulfide has no conductivity, it no longer functions as an electrode.

Next, a procedure for assembling the bag-shaped body 30 will be explained.

An electrostrictive element 3 having a permanent magnet 22 attached to its tip is inserted into a bag-like body 30, and valve bodies 41 and 42 are attached to both surfaces of the bag-like body 30. Although the permanent magnet 22 is fixed to the electrostrictive element 3 by adhesive, it is placed inside a bag-like body 30 to further protect the fixation.

The bag portion 30a of the bag-like body 30 is inserted into the air space 100 of the main body 1, the ribs 30c of the collar portion 30b are arranged to face the main body 1 side, and the presser 56 is pressed from above. The charging portion of the electrostrictive element 3 and the resistor 7 are integrally molded with a polymer material 8.

(Effects of the invention) As explained in detail above, according to the invention,
Since the electrostrictive element is inserted into a flexible bag-like body that is water resistant, oil resistant, and heat insulating, the electrostrictive element can be protected from moisture, oil, and rapid temperature changes. All inconveniences can be resolved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the electronic valve according to the present invention, and FIG. 2 is a perspective view showing an example of a bag-like body used in the electronic valve according to the present invention. FIG. 3 is a sectional view showing the basic structure of the electronic valve, and FIG. 4 is a perspective view showing an example of an electrostrictive element used in the electronic valve. 1... Main body, 10... Guide groove, 11, 12...
... Valve seat member, 11a, 12a... Valve seat, 11b,
12b...screw part, 11c, 12c...pressing surface,
21, 22... Permanent magnet, 3... Electrostrictive element, 30
... Bag-like body, 31, 32 ... Piezoelectric ceramic, 33 ...
Metal plate, 41, 42... Valve body, 51... Element holder, 53... Bush, 54... Lid, 55... Screw, 56... Holder, 6... Lead wire, 7... Resistor, 8... Polymer material, 91, 91a, 92,
92a...O-ring.

Claims (1)

[Scope of utility model registration request] a valve having a first port facing the air space, a second valve seat facing the first valve seat, and a third port respectively connected to the air space; a main body; an electrostrictive element having a bimorph structure fixed to the main body at a base such that the tip extends beyond the first and second valve seats; and a water-resistant element covered with the electrostrictive element and sealed at the base; an oil-resistant and heat-insulating flexible bag-like body; and first and second valve-like bodies provided on the electrostrictive element via the bag-like body so as to face the first and second valve seats. An electronic valve comprising a valve body and configured to switch the direction of a working fluid by driving the electrostrictive element to open and close first and second valve seats.