JPH10259877A - Control valve with heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a clearance between a rotational type valve element and a circular fluid passage, improve shut-off performance at the time of full closing, and enable minute flow rate controlling. SOLUTION: A circular fluid passage 13 is formed on a valve body (base) 14 of a control valve 10. A heater 30 is arranged inside a hollow valve shaft 12 journalled by the valve body 14. A valve element 20 having a diameter suited to the fluid passage 13 is fixed. The valve element 20 is heated by the heater 30 inside the valve shaft 12, and a Teflon valve plate 20a composing the valve element 20 is thermally expended in a diameter direction, to decrease a clearance between the fluid passage 13 and the valve element 20. A degree of thermal expansion of the valve plate 20a is adjusted by the voltage applied to the heater 30, and thereby the clearance between the fluid passage 13 and the valve element 20 is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control valve (usually a "butterfly valve") for rotating a valve provided in a circular fluid passage of a valve body (base) to open and close the fluid passage.
Called. ).

[0002]

FIG. 6 shows a conventional control valve of this kind.
The control valve 60 has a valve body (base) 64 having a circular fluid passage 63 and a disc-shaped valve body 70 that fits the fluid passage 63. The valve body 70 includes the valve body 6.
The valve shaft 62 is fixed to a valve shaft 62 penetrating the motor 4, and is connected to a motor 66. The valve body 70 is rotated by the motor, and the circular fluid passage 63 is opened and closed. The conventional control valve 60 is provided with a rubber O-ring on the outer periphery of the valve body 70 to emphasize a shut-off function in a closed state, and a type that emphasizes operability and control function without an O-ring. There is a type that did.

[0003]

However, in a control valve which emphasizes a shut-off function in a closed state, when the valve body 70 is closed, an O-ring provided on the outer periphery of the valve body 70 has a fluid passage 63.
Therefore, there is a problem that friction powder is generated and mixed into the liquid. On the other hand, in the case of a control valve having no O-ring, a slight gap is previously provided between the fluid passage 63 and the valve body 70 so that the inner periphery of the valve body 64 does not contact the valve body 70. At times, there is a problem that the fluid easily leaks and it is difficult to control the minute flow rate.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a control valve for controlling the opening and closing of a circular fluid passage provided in a valve body by providing a valve body which is rotated by a valve shaft. By the control valve characterized by
The above problem has been solved. In a typical embodiment of the present invention, the heater is provided inside the valve shaft, and the valve body has a valve plate made of Teflon, and a pair of metal valve plates sandwiching the valve shaft and the valve plate. It consists of a fixed plate. When the valve element has a tapered surface or a curved surface that converges in the flow direction of the fluid when the fluid path is closed, the effective area of the fluid path changes greatly due to the rotation of the valve element. Prevention and finer flow rate control.

[0005]

FIG. 1 is a sectional front view of a main part of a control valve 10 according to the present invention. The control valve 10 has a valve body (base) 14 having a fluid passage 13 having a circular cross-sectional shape, and a substantially disc-shaped valve body 20 that fits the fluid passage 13. The control valve 10 is made of a metal such as stainless steel (SUS) as a whole except for a part of the valve body 20.

The valve body 20 is fixed to a valve shaft 12 supported by a valve body 14, and the valve shaft 12 is connected to a motor 16. When the valve body 20 is rotated by the operation of the motor 16, the fluid passage 13 having a circular cross section is opened and closed. The control valve 10 is provided with a valve body 2 by sliding friction between the fluid passage 13 and the valve body 20 when the valve body 20 rotates.
A small gap is formed between the fluid passage 13 and the valve body 20 even when the valve is fully closed so as not to hinder the rotation function of the valve.

FIG. 2 is a perspective view showing a state where the valve shaft 12 and the valve body 20 are separated. A disc-shaped valve plate 20a having a diameter adapted to the fluid passage 13 of the valve body 14 includes:
Notches 20e extending in the diameter direction for receiving the valve shaft 12, and circular recesses 20f, 2 for receiving the valve plate fixing plates 20b, 20c sandwiching both side surfaces of the valve plate 20a.
0 g is formed. Like the valve plate 20a, one of the valve plate fixing plates 20b is provided with a notch 20h extending in the radial direction for receiving the valve shaft 12, whereas the other valve plate fixing plate 20c has such a notch. No notches are provided.

FIG. 3 is a sectional view taken along line 3-3 of FIG. The valve plate 20a receives the valve shaft 12 in the notch 20e and receives the valve plate fixing plate 20b and the valve plate fixing plate 20c in the side recesses 20f and 20g, respectively.
It is fixed by two fixing screws 20d. Valve body 20
In the above, the valve plate 20a is made of Teflon (tetrafluoroethylene), and the others are made of metal such as stainless steel. In addition, the material of the configuration other than the valve plate 20a is not limited to stainless steel, but stainless steel is lightweight and corrosion-resistant, so when controlling the flow rate of corrosive gas, It is suitable.

FIG. 4 is a longitudinal sectional view of the valve shaft 12. A heater 30 is provided in the hollow interior of the cylindrical valve shaft 12 via a lead wire 31. As the heater 30, an appropriate electric heater such as a nichrome wire type or a tungsten wire type can be used.

[0010] Teflon is about 10 times less than stainless steel.
When the heater 30 inside the valve shaft 12 is energized, the valve shaft 12, the valve plate 20a, and the valve plate fixing plates 20b and 20c are heated because the heater 30 inside the valve shaft 12 is heated, but the Teflon valve plate 20a Thermally expands significantly in the radial direction. The radially expanded valve plate 20 a reduces the gap between the fluid passage 13 and the valve body 20.

In actual use, a constant voltage is applied to the heater 30 to generate heat.
A method of controlling the flow rate of the fluid by rotating the valve body 20 in a state where the gap between the valve body 3 and the valve plate 20a is reduced in advance, and a case where the valve body 20 is normally closed without using the heater 30 There is a method in which only the heater 30 is energized and the gap between the fluid passage 13 and the valve plate 20a is finely adjusted according to the strength of the voltage to finely control the flow rate. In addition, it goes without saying that the heater 30 can be used in the same manner as in the related art without energizing the heater 30 at all, other than the above method.

FIG. 5 is an example of a diagram showing the relationship between the temperature of the valve plate 20a and the outflow of fluid in the control valve 10 of the present invention when the opening of the valve is kept constant.

The shape of the valve body 20 of the control valve 10 of the present invention is as follows.
The cross section is formed so as to be a curved surface converging in the flow direction of the fluid, but is not limited to this shape. For example, as disclosed in JP-A-7-317919, Instead, a tapered surface may be adopted. When the valve element 20 is formed to have a tapered surface or a curved surface, the effective area of the flow path changes greatly even if the valve element 20 rotates slightly, in a range where the rotation angle of the valve element 20 with respect to the valve body 14 is relatively small. Is prevented.

As an embodiment of the present invention, the valve shaft 12 having the heater 30 built therein has been described.
The place where the heater 30 is provided is not limited to the inside of the valve shaft. It is also possible to provide it on the valve plate itself.

[0015]

According to the structure of the present invention, since the valve element can be heated by the heater, the valve element is expanded in the radial direction, and is provided beforehand between the fluid passage and the valve element in the fully closed state. By reducing the gap, the shut-off function can be enhanced, and the control of the minute flow rate can be performed. In addition, the degree of thermal expansion of the valve element can be adjusted by the voltage applied to the heater, and the gap between the flow paths can be adjusted more finely. It is possible to control the flow rate appropriately.

Further, since the valve element is heated by the heater, it is possible to prevent contaminants from adhering to the valve element and prevent liquefaction of gas. And, by forming a tapered surface or a curved surface in the valve body, it is possible to prevent the effective area of the fluid passage from largely changing due to the rotation of the valve body,
Finer flow rate control becomes possible.

[Brief description of the drawings]

FIG. 1 is a front view showing a cross section of a main part of a control valve of the present invention.

FIG. 2 is a perspective view in which a valve shaft and a valve element are separated.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is a longitudinal sectional view of a valve shaft.

FIG. 5 is a diagram showing the relationship between the temperature of a valve body and the outflow amount of a fluid.

FIG. 6 is a front sectional view of a conventional control valve.

[Explanation of symbols]

10: Control valve 12: Valve shaft
13: Fluid passage 14: Valve body 20: Valve body 2
0a: Valve plate 20b: Valve plate fixing plate 20c: Valve plate fixing plate
30: heater

Claims (3)

[Claims] 1. A control valve for providing a valve body which is rotated by a valve shaft and for opening and closing a circular fluid passage provided in a valve body, wherein the valve body is provided with a heater. 2. The heater is provided inside the valve shaft, and the valve body is made up of a Teflon valve plate and a pair of metal valve plate fixing plates sandwiching the valve shaft and the valve plate. The control valve according to claim 1. 3. The control valve according to claim 1, wherein the valve body has a tapered surface or a curved surface that converges in a flow direction of the fluid when the fluid passage is closed.