JPH0220548Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a piezoelectric element valve, and more particularly to a piezoelectric element valve for injecting raw material gas into a vacuum vessel for a nuclear fusion device in a gas injection device for a nuclear fusion device.

Prior Art This type of piezoelectric element valve is composed of a piezoelectric element, a seal rubber, a valve seat, a ceramic stand, an adjustment spring, etc. By applying a voltage to the piezoelectric element, the seal rubber held by the piezoelectric element is affected by the force of the adjustment spring. When it is pulled away from the valve seat against resistance, gas flows out through the gap created between the seal rubber and the valve seat, and when the voltage to the piezoelectric element becomes OV, the seal rubber seats on the valve seat and the gas flow stops. The voltage is cut off and the voltage is applied in a pulse waveform. Conventional piezoelectric element valves use fluorine rubber as the material for the seal rubber, and stainless steel for the valve seat.

Problems that the invention aims to solve By the way, when the piezoelectric element is not in use, the sealing rubber is in contact with the valve seat, so the two are in a state of abutment under pressure. Even though fluorine rubber has superior heat resistance and oil resistance compared to fluorine rubber, it tends to stick to the valve seat and deformation due to residual distortion cannot be avoided.

On the other hand, piezoelectric element valves used in nuclear fusion devices attempt to match the set flow rate with the actual flow rate using a drive method that introduces the set flow rate in a pulse waveform based on the flow rate-voltage characteristics measured in advance. Therefore, it is extremely important that the flow rate-voltage characteristics of the piezoelectric element valve do not change over time and always remain constant.

In view of the above points, the present invention has been developed to reduce the flow rate of the piezoelectric element valve.
The purpose is to improve the reproducibility of voltage characteristics.

Means to Solve the Problem To achieve this, the present invention focuses on the adhesion phenomenon and deformation caused by permanent deformation on the contact surface between the seal rubber and the valve seat, and in order to reduce this as much as possible, numerous and diverse experiments were repeated. As a result, we adopted compressed nitrile rubber as the material for the seal rubber, and applied a fluorine resin coating to the contact surface of either or both of the seal rubber and the valve seat, and by combining the two, we reproduced the problem. This makes it possible to obtain a piezoelectric element valve with extremely good performance.

Function In the piezoelectric element valve of the present invention, by applying a voltage to the piezoelectric element 3, the piezoelectric element 3 is displaced to the left in FIG. A gap is created, gas flows,
Furthermore, if the voltage applied to the piezoelectric element 3 is set to OV, the displacement of the piezoelectric element 3 returns to its original state, and the seal is maintained between the seal rubber 1 and the valve seat 2. Nitrile rubber is used as the material for the seal rubber 1, and is compressed to minimize permanent distortion, and the contact surface of the valve seat 2 is coated with a fluorine resin film 4 to prevent adhesion. As a result, very good reproducibility performance can be obtained. The coating of the fluorine resin film 4 is applied not only to the abutting surface of the valve seat 2 but also to one or both of the abutting surfaces of the seal rubber 1 as appropriate.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of the main part of FIG. 2, and the seal rubber 1 is made of compressed nitrile rubber and is usually held on the piezoelectric element 3 by adhesive, while the valve seat 2 is made of, for example, stainless steel. Made of steel;
At least the contact surface with the seal rubber 1 or the contact surface including the peripheral surface thereof is coated with a fluororesin film 4. This fluorine resin film can be coated on the contact surface on the seal rubber side, or it can be applied on both.

Figure 2 shows an overall view of a piezoelectric element valve for injecting raw material gas into a vacuum vessel for a fusion device (not shown), and shows pipes communicating with the vacuum vessel side for a fusion device and the gas supply side, respectively. The fixed outlet side flange 19 and the inlet side flange 9 are bolted together at the peripheral edges of both flanges, and the outlet side flange 19 forms an outlet side wall. A passage is bored in the center of the inner wall of the outlet flange 19, and a valve seat 2 having a truncated conical head is fixed with bolts.
6 is installed. A seal rubber 1 is adhered to the center of the piezoelectric element 3, and the seal rubber 1 insulates the piezoelectric element 3 from the valve seat 2, and opens or closes the gap between the piezoelectric element 3 and the valve seat 2 depending on the presence or absence of a voltage applied to the piezoelectric element 3. make up the body. The seal rubber 1 is made of nitrile rubber subjected to compression treatment at high temperature or room temperature, and the composition ratio of acrylonitrile and butadiene is appropriately selected in consideration of aging resistance, abrasion resistance, etc. One or both of the abutment surfaces between the seal rubber 1 and the valve seat 2, which is usually made of stainless steel, are coated with a fluorine resin film. The piezoelectric element 3 has a rubber sheet 11 bonded to the same position on the opposite side of the seal rubber 1 for insulating it from a spring 14 or a spring holder 10, which will be described later.

The piezoelectric element 3 is held at its periphery by an annular insulating plate 6 and three fan-shaped push plates 7 arranged on the insulating plate 6 at approximately equal intervals in the circumferential direction, and is fitted into a bolt 20 inserted from the insulating plate 6 side. The inserted nut and the push plate 7 are crimped and fixed by a spring 15 interposed between them, and a lock pin 17 serves to prevent the nut from loosening. The spring holder 10 includes an adjustable spring 14 that presses the piezoelectric element 3 toward the valve seat 2, and has holding arms extending radially from the center. Insulating plate 6 and spring holder 1
0 to the outlet side flange 19, the annular adjusting plate 5, annular insulating plate 6, insulating ring 8, and the retaining arm of the spring holder 10 are sequentially overlapped on the inner surface of the outlet side flange 19, and then attached to the adjusting seat 18 with bolts. It's stuck.

Figures 3 and 4 are charts showing comparative test results of the piezoelectric element valve according to the present invention and the piezoelectric element valve according to the conventional example, in which the same piezoelectric element valve was tested four times on different days. conduct,
(In Figure 3, December 28th, January 7th, February 21st of the following year)
4 times in total on Sunday, March 7th, and April 23rd and April 4th in Figure 4
28th, August 2nd, and August 22nd) shows how the voltage-flow characteristics changed over time. According to FIG. 3, when the piezoelectric element valve according to the present invention is implemented, the change over time is almost negligible, and all the characteristics clearly show linearity, whereas according to FIG. The effect of the invention is that it can be seen that piezoelectric element valves not only change significantly over time, but also cannot be expected to be accurate in terms of linearity.As described above, according to the invention, the permanent strain of the nitrile rubber that constitutes the seal rubber 1 is minimized. In addition, the valve seat 2 or seal rubber 1 is coated with a fluorine resin film to prevent adhesion, so not only can excellent reproducibility performance be obtained, but individual The voltage-flow rate characteristic also shows clear linearity, making it possible to easily and accurately determine the applied voltage for the set flow rate, and preventing the injection of raw material gas from becoming inaccurate due to deterioration in reproducibility. Since there is no risk of operation failure, and operations that consume large amounts of power can be performed efficiently, this greatly contributes to power savings.

[Brief explanation of drawings]

Fig. 1 is an enlarged sectional view of the main part of Fig. 2, Fig. 2 is an overall vertical sectional view showing an embodiment of the present invention, Fig. 3 is a voltage-flow diagram according to the present invention, and Fig. 4 is a conventional one. An example voltage-flow diagram, FIG. 5, is a view taken along arrow A in FIG. 2. 1... Seal rubber, 2... Valve seat, 3... Piezoelectric element, 4... Fluorine resin film, 6... Insulating plate, 7...
Holding plate, 9... Inlet side flange, 10... Spring holder, 14... Spring, 16... Current introduction terminal.

Claims (1)

[Scope of utility model registration request] In a piezoelectric element valve that injects raw material gas into a vacuum vessel for a nuclear fusion device, the seal rubber that contacts the valve seat is made of compressed nitrile rubber, and either or both of the contact surfaces of the seal rubber and the valve seat are A piezoelectric element valve coated with fluorine resin.