JP2516824Y2 - Control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a control valve used in a flow rate control unit such as a mass flow controller.

[Conventional technology]

In the above control valve, one in which the valve body that opens and closes the valve opening is pressed by the strain force of the piezo stack has come into practical use.

FIG. 6 schematically shows a structure for holding a piezo stack in a conventional control valve. In FIG. 6, 61 is a piezo stack formed by stacking a plurality of piezo elements (piezoelectric elements), which is a main block of the control valve. It is housed in a valve case 63 that is erected on the upper surface of 62. Reference numeral 64 is an adjustment nut screwed onto the upper portion of the valve case 63, and fixes the upper fixing portion 61A of the piezo stack 61. 65 is piezo stack 6
The valve body is provided so as to abut the lower surface of the lower movable portion 61B of 1, and is elastically held by, for example, a diaphragm 66.

When a predetermined DC voltage is applied to the piezo stack 61, each piezo element of the piezo stack 61 is distorted, and the lower movable portion 61B is displaced downward. It descends and the opening degree of the valve opening 67 is adjusted. In addition, 68 is an orifice block and 69 is a fluid flow path.

[Problems to be solved by the device]

By the way, in the case where the valve body 65 is pressed and driven by the strain force of the piezo stack 61 as described above,
It is absolutely required to prevent any movement other than distortion due to voltage application from occurring at the time of setting the position of 61 and after the position setting. However, the above-mentioned conventional technique has the following drawbacks. .

That is, in the piezo stack 61, both the upper fixed portion 61A and the lower movable portion 61B are formed in a horizontal plane, and are in contact with the lower surface of the adjusting nut 64 and the upper surface of the valve body 65, respectively. Therefore, if the parallelism between the upper fixed portion 61A and the lower movable portion 61B is not perfect or the verticality of the valve case 63 is not sufficient, for example, as shown by the phantom line in FIG. And valve body 65
Is a so-called one-sided contact, and the strain output of the piezo stack 61 is not completely transmitted to the valve body 65, and as a result, the valve body does not operate as set and may interfere with predetermined flow rate control. is there. In addition, the set value may shift due to external force such as vibration.

The present invention has been made in consideration of the above-mentioned matter, and its purpose is to ensure that the strain output is ensured by holding the piezo stack so that no movement other than the strain due to the voltage application occurs. It is to provide a control valve that can be transmitted to the valve body.

[Means for solving the problem]

In order to achieve the above-mentioned object, the control valve according to the present invention comprises:
It is characterized in that the upper fixed portion of the piezo stack is supported by a ring-shaped tapered surface or a spherical surface, and the lower movable portion of the piezo stack is connected to the valve body via a spherical bearing portion.

[Action]

According to the above configuration, the upper fixing portion of the piezo stack is
Since it is supported by a ring-shaped tapered surface or spherical surface,
Even if the piezo stack receives an upward force or a lateral force, its movement is limited. Even if the parallelism between the surfaces of the upper fixed part and the lower movable part and the verticality of the case that houses the piezo stack is not perfect, an even contact surface can be obtained, and the lower movable part can be valved through the spherical bearing part. Since it is connected to the body, the piezo stack receives a lateral force, and even if the parallelism and verticality are not perfect, the strain output of the piezo stack can be reliably transmitted to the valve body. Is completely achieved.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a so-called normal open type mass flow controller. In FIG. 1, 1 is a main body block, and 2 and 3 are fluid inlets and fluid outlets formed in the main body block 1. A fluid flow path 4 is formed between the fluid inlet 2 and the fluid outlet 3, and is provided with a mass flow meter section 5 and a control valve 6 as a flow rate control section. In the illustrated example, the mass flow meter unit 5 is provided on the upstream side of the control valve 6, but this arrangement may be reversed.

The mass flow meter unit 5 has a conduit 9 made of, for example, a thin capillary tube that connects a measurement flow path inlet 7 and a measurement flow path outlet 8 opened so as to face the fluid flow path 4, for example, a thermal mass flow sensor. The thermal mass flow sensors 10 and 10 are connected to a bridge circuit (not shown). Reference numeral 11 is a bypass portion formed in the fluid flow path 4 and having a constant flow ratio characteristic.

The control valve 6 is constructed as follows. That is, the fluid flow path 4 on the downstream side of the bypass section 11
Is provided with an orifice block 13 having a valve opening 12, and a valve head 14 is composed of a plunger portion 15 and a valve body 16 for adjusting the opening of the valve opening 12 brings the valve head 14 close to the valve opening 12. It is provided in the opened state. A small gap is formed between the valve body 16 and the orifice block 13 in the normal state by the metal diaphragm 18 provided in the lower space of the valve block 17 provided at the upper portion of the main body block 1. It is held so that it can move up and down. 19 is the diaphragm
The spring is interposed between the spring receiver 18 fixed to the plunger portion 15 and the spring receiver 18.

Reference numeral 21 denotes a piezo stack for pressing and driving the valve body 16 in a predetermined direction, which is formed by laminating a plurality of piezo elements, and is housed in a tubular valve case 22 screwed to the valve block 17. . The holding structure of the piezo stack 21 in the valve case 22 will be described with reference to FIG.

A shoulder portion 23, which is an upper fixed portion of the piezo stack 21, is formed in a so-called tapered surface which is inclined obliquely downward. Then, the ring-shaped inner contact surface 26 of the flange portion 25 of the union nut-shaped adjustment nut 24 screwed to the screw portion formed on the outer periphery of the upper portion of the valve case 22 is formed into a spherical shape, and this inner contact is formed. The surface 26 is in contact with the upper fixing portion 23 of the piezo stack 21.

Further, a conical recess 28 is formed at the center of the lower surface of the lower movable portion 27 of the piezo stack 21, while an inverted conical shape that is vertically symmetrical with the recess 28 is formed at the center of the upper surface of the plunger portion 15 of the valve body 16. The depressions 29 are formed, and these depressions 28, 29 are both formed.
The spherical bearing part 31
Is formed between the lower movable portion 25 and the plunger portion 15.

In FIG. 1, 32 is a lock nut, and 33 to 39 are metal O-rings as seal members.

Thus, in the above configuration, since the upper fixing portion 23 of the piezo stack 21 is formed into a tapered surface and is supported by the ring-shaped spherical surface, even if the piezo stack 21 receives a force in the upward or left-right direction, almost that Movement is restricted. And
Even if the parallelism between the surfaces of the upper fixed portion 23 and the lower movable portion 27 and the verticality of the case 22 that houses the piezo stack 21 is not perfect, an even contact surface can be obtained, and the lower movable portion 27 can have a spherical bearing portion 31. Since it is connected to the valve body 16 via the piezo stack 21, even if the piezo stack 21 receives a force in the left-right direction or the parallelism and verticality are not perfect, the strain output of the piezo stack 21 can be reliably applied to the valve body 16. It can be transmitted.

The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways.

That is, as shown in FIG. 3, the upper fixing portion 23 of the piezo stack 21 is formed into a spherical shape, while the inner contact surface 26 of the flange portion 25 of the adjusting nut 24 is formed into a tapered surface, and further the lower movable portion is movable. Each of the recess 28 formed on the lower surface of the portion 27 and the recess 29 formed on the upper surface of the plunger portion 15 of the valve body 16 has a spherical shape.
It may be formed in a spherical shape along the outer shape of 30.

Further, as shown in FIG. 4, a hemispherical portion 40 may be provided so as to project above the plunger portion 15.

Further, the present invention can be applied to a so-called normal close type mass flow controller, and FIG. 5 shows an example of its configuration. In this figure, the same parts as those shown in FIG. 1 indicate the same or equivalent parts. In this figure, 41 is a guide block, 42 is a spring 43.
Is constantly energized by the upper orifice block 13
, 44 is a plunger nut, and 45 is a metal O-ring as a seal member.

[Effect of device]

As described above, in the present invention, since the upper fixing portion of the piezo stack for pressing and driving the valve body is supported by the ring-shaped tapered surface or the spherical surface, the piezo stack is forced to move in the upward or horizontal direction. Even if you receive it, its movement is limited. Even if the parallelism between the surfaces of the upper fixed portion and the lower movable portion and the verticality of the case that houses the piezo stack is not perfect, an even contact surface can be obtained, and the lower movable portion can be valved through the spherical bearing portion. Because it is connected to the body, the piezo stack receives lateral force,
Even if the parallelism and the verticality are not perfect, the strain output of the piezo stack can be reliably transmitted to the valve body.

That is, according to the present invention, since even contact surfaces can be obtained in the upper fixed portion and the lower movable portion of the piezo stack for pressing and driving the valve body, the piezo stack undergoes movements other than strain due to voltage application. Therefore, the strain output can be reliably transmitted to the valve element, and the control accuracy of this type of control valve is improved.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a vertical cross-sectional view showing a normally open type mass flow controller incorporating a control valve according to the present invention, and FIG. 2 is a piezo stack holding device. It is a fragmentary sectional view showing an example of a structure. FIG. 3 is a partial sectional view showing another embodiment of the holding structure for the piezo stack. FIG. 4 is a partial sectional view showing another embodiment of the coupling structure of the lower movable portion of the piezo stack and the valve body. FIG. 5 is a vertical sectional view showing a normally closed type mass flow controller incorporating a control valve according to the present invention. FIG. 6 is a sectional view showing a conventional example. 6 ... Control valve (flow rate control unit), 12 ... Valve port, 16 ... Valve body, 21 ... Piezo stack, 23 ... Upper fixed part, 27 ...
Lower movable part, 31 …… Spherical bearing part.

Front Page Continuation (72) Inventor Tetsuo Shimizu 2 Higashi-cho, Kichijoin-miya, Minami-ku, Kyoto-shi, Kyoto, Japan (56) References JP-A-62-215177 (JP, A) JP-A-62-124373 ( JP, A) JP-A-61-127983 (JP, A) JP-A-31-12068 (JP, Y1)

Claims (1)

(57) [Scope of utility model registration request] 1. A control valve in which a valve body for opening and closing a valve opening is pressed and driven by a strain force of a piezo stack, wherein an upper fixing portion of the piezo stack is supported by a ring-shaped tapered surface or a spherical surface, and the piezo stack is supported. A control valve characterized in that the lower movable part of the stack is connected to a valve body via a spherical bearing part.