JPH11108227A - Flow rate control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate control valve using a support receiving structure of a piezoelectric actuator solved a problem of an assembly workability without impairing function of a conventional support receiver. SOLUTION: This flow rate control valve is opened/closed by push-pressing and driving a valve element 45 to a valve seat 43 by distortion force of a piezoelectric actuator 50. An upper part of the piezoelectric actuator 50 is formed as an annular outer taper surface 62 which is supported by an annular inner taper surface 61. A recessed part 55 or a projection part is arranged on a center of a lower surface of the piezoelectric actuator 50, and distortion force of the piezoelectric actuator 50 is transferred to the valve element 5 through the projection part 54 or the recessed part which is received while being brought in linear contact with the inner surface of the recessed part or the outer surface of the projection part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control valve used for flow control in a mass flow controller, for example, and more particularly to a support structure for a piezoelectric actuator serving as a driving source thereof.

[0002]

2. Description of the Related Art According to Japanese Utility Model Registration No. 2516824, a support receiving structure for a piezoelectric actuator in a flow control valve is proposed. This is because, as shown in FIG. 3, the upper part of the piezoelectric actuator 90 composed of the laminated piezoelectric element body has an annular outer tapered surface or a spherical surface 92.
This is formed into an annular spherical surface or inner tapered surface 9 on the nut 97 side.
1, while a concave portion 93 is provided in the lower portion of the piezoelectric actuator 90, and the concave portion 94
And a spherical bearing is formed by interposing a sphere 95 between the two concave portions. Thus, even if the piezoelectric actuator 90 receives a force in the left-right direction, its movement is restricted, and the distortion force of the piezoelectric actuator 90 can be reliably transmitted to the valve body.

[0003]

The above-described support receiving structure for a piezoelectric actuator is excellent in that it can reliably transmit the minimal distortion force of the piezoelectric element. However, on the other hand, since the support structure on the upper part of the piezoelectric actuator is a combination of a tapered surface and a spherical surface, processing is slightly troublesome. In addition, since the lower receiving structure is a spherical bearing using a sphere, handling of the sphere is troublesome. That is, since this sphere is extremely small, about 2 mm, it is difficult to assemble it in a concave portion and it is difficult to assemble it.

Accordingly, an object of the present invention is to provide a flow control valve using a support structure of a piezoelectric actuator which solves the above-described problem of the assembling workability without impairing the function of the conventional support receiver.

[0005]

According to the present invention, there is provided a flow rate control valve which opens and closes a valve body by pressing and driving a valve body against a valve seat by a distortion force of a piezoelectric actuator, wherein an upper portion of the piezoelectric actuator is formed as an annular outer tapered surface, The annular outer tapered surface is supported by an annular inner tapered surface, while a concave portion or a convex portion is provided at the center of the lower surface of the piezoelectric actuator, and the convex portion or the concave portion is received in line contact with the concave inner surface or the convex outer surface. A flow control valve that transmits the distortion force of the piezoelectric actuator to the valve body via the valve. In addition, the concave portion and the convex portion have a taper shape having a conical surface and an angle of a cone on a side receiving a force is larger than the other, for example, a conical taper angle of the convex portion is larger than a taper angle of the concave portion. It is desirable that the outer surface of the convex taper be supported in line contact with the inner surface of the concave taper over the entire circumference.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment in which the flow control valve of the present invention is used in a mass flow controller. FIG. 2 is a vertical cross-sectional view when the present invention is applied to another mass flow controller. Hereinafter, these mass flow controllers will be described as examples.

First, the overall configuration of the mass flow controller shown in FIG. 1 will be described. Mass flow controller 1A
Comprises a sensor unit 2, a bypass unit 4, a flow control valve 5, and a control circuit unit 3. Sensor part 2
Has a thermosensitive coil wound on each of an upstream side and a downstream side of a sensor pipe branched from a main flow path, and further combined with this and other resistors to form a bridge circuit. The temperature of the heat-sensitive coil on the upstream side is deprived of heat by the flow of the gas, and the temperature of the coil decreases. On the other hand, the temperature of the downstream coil rises due to the flow of the gas warmed on the upstream side, causing a temperature gradient. Such heat transfer is detected as an unbalanced voltage of the bridge circuit, and since this potential difference is proportional to the mass flow rate, it functions as a mass flow rate sensor. A bypass flow path 4 is obtained by bundling a predetermined number of the same pipes as the sensor pipe and setting a predetermined flow rate ratio.

Next, the flow signal from the mass flow sensor 2 is amplified by an amplifier circuit, and then input to a comparison control circuit. Here, the flow rate is compared with a preset flow rate signal, and a valve drive voltage that eliminates the difference is input to the flow rate control valve. As a result, the gas flow rate can be controlled by adjusting the opening degree of the valve body. . These controls are performed by the control circuit unit 3 (not shown).

The main body of the flow control valve 5, which is common to the mass flow controller main body 40, is made of stainless steel (SUS316L) or the like and has an integral block shape including a joint portion. Metal valve seat 4 in the middle of the flow path
3 is mounted by caulking means, and a metal diaphragm 45 serving as a valve body is disposed facing the valve seat 43. This metal diaphragm 45 allows the inflow-side flow path 42
And the outflow side flow path 44 are partitioned. On the mirror-finished main body upper surface 46, a metal diaphragm 45 is placed on the main body upper surface 46 via a metal O-ring 66, a spacer 65, and a valve seat spacer (not shown). Thus, a peripheral portion of the metal diaphragm 45 is sandwiched, and a housing 57 is erected thereon, and this is fastened to the main body 40 by a bolt via a lid 58. On the other hand, a disk-shaped diaphragm spacer 51 is mounted on the upper surface of the metal diaphragm 45, and a hard ball 52 having a centering action and a valve rod 53 are mounted thereon so as to transmit the pressing force of the piezoelectric actuator 50. ing. The spring 63 works to always push the piezoelectric actuator 50 upward, and the bearing 64
Is supported so that it does not tilt.

The piezoelectric actuator 50 has a laminated piezoelectric element sealed in a case made of a metal such as stainless steel, preferably a metal material having a very small coefficient of thermal expansion. The housing 57 is screwed together with its axis aligned, that is, the inner tapered surface 61 and the outer tapered surface 62 are supported together. On the other hand, a triangular pyramid-shaped concave portion 55 is provided at the center of the lower surface of the piezoelectric actuator 50, whereas a triangular pyramid-shaped convex portion 54 having a slightly larger angle than the concave portion 55 is provided at the upper center of the valve stem 53. Is formed. Therefore, the piezoelectric actuator 50 is supported and received by matching these concave and convex portions 55 and 54. As described above, the piezoelectric actuator 50 is installed vertically in the housing 57, and can maintain the state by correcting the tilt and maintaining the state almost in the same manner as the ball bearing even when a vertical and horizontal force is applied. Further, the strain force of the piezoelectric actuator 50 can be transmitted to the metal diaphragm valve element 45 accurately.

Incidentally, the mass flow controller 1A
Normally, the piezoelectric actuator 50 is pushed up by the spring 63, and the metal diaphragm 45 pushes up the diaphragm retainer 56 and the like by its own elastic restoring force, and is in a valve-open state. When the piezoelectric actuator 50 is energized, the extension force pushes down the valve rod 53 against the spring 63 to move the metal diaphragm 45 to the valve seat side. After that, it is a normally open type mass flow controller that controls the amount of movement of the metal diaphragm 45 to control the flow rate.

Next, the mass flow controller 1B shown in FIG. 2 is a normally closed type mass flow controller. The point is that a bridge 78 passing through the housing 77 and the valve stem 73 is fastened to the main body 40 using bolts. In the space between the lower part of the bridge 78 and the valve stem 73, a spring 84 and a spring receiver 83 are provided.
3 is always pressed down. On the other hand, a triangular pyramid-shaped concave portion 74 is formed on the upper portion of the bridge 78, while a triangular pyramid-shaped convex portion 75 is also formed on the piezoelectric actuator 70 side. Therefore, the piezoelectric actuator 70 can be supported and received with a centering action by aligning the irregularities 74 and 75 and supporting the upper tapered surfaces 81 and 82.

Incidentally, this mass flow controller 1B
Normally, the valve rod 73 is pushed down by the spring 84 and the metal diaphragm 45 is pressed against the valve seat 43 to be in a closed state. When the piezoelectric actuator 70 is energized, the extension force is reversed by the bridge 78 and converted into a force that pushes up the valve stem 73 against the spring force. Therefore, the metal diaphragm 45 is lifted up by its own elastic restoring force and fluid pressure to be in an open state. Thereafter, it is a normally closed type mass flow controller that controls the flow rate by adjusting the moving amount of the metal diaphragm 45.

[0014]

The support structure for a piezoelectric actuator according to the present invention is not a ball bearing using a ball, so that the ball can be easily assembled without being lost or forgotten. In addition, there is a resistance to the vertical and horizontal forces applied to the piezoelectric actuator, and the assembly state can be maintained. Further, the distortion force of the piezoelectric actuator can be accurately transmitted to the metal diaphragm valve.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a mass flow controller using a flow control valve of the present invention.

FIG. 2 is a longitudinal sectional view of another mass flow controller using the flow control valve of the present invention.

FIG. 3 is a longitudinal sectional view of a mass flow controller showing an example of the related art.

[Explanation of symbols]

1A: Mass flow controller 2: Sensor section 3: Control circuit section 4: Bypass section 5: Flow control valve 40: Mass flow controller main body 43: Valve seat 45: Metal diaphragm valve body 50: Piezoelectric actuator 51: Diaphragm spacer 52: Hard ball 53: Valve stem 54: Receiving convex portion 55: Receiving concave portion 56: Diaphragm holding 57: Housing 58: Lid 59: Housing cap 61: Inner tapered surface 62: Outer tapered surface

Claims (1)

[Claims] 1. A flow control valve which opens and closes a valve body by pressing and driving a valve body against a valve seat by a distortion force of a piezoelectric actuator, wherein an upper portion of the piezoelectric actuator is formed as an annular outer tapered surface,
The annular outer tapered surface is supported by an annular inner tapered surface, while a concave portion or a convex portion is provided at the center of the lower surface of the piezoelectric actuator, and the convex portion or the concave portion is received in line contact with the concave inner surface or the convex outer surface. Wherein the strain force of the piezoelectric actuator is transmitted to the valve element via a valve.