JP2762920B2 - Flow control valve - Google Patents

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 capable of finely controlling a pressure or a flow rate. Such a flow control valve is used for a flow path for supplying a carrier gas in a gas chromatograph, for example.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional flow control valve.
In the drawing, reference numeral 1 denotes a nozzle constituting a valve seat provided at one end of a flow path 8, and 2 denotes a seal packing which is held at one end of a valve shaft 4 and abuts against an end face 1 'of the nozzle 1, and the flow path Is to shut off. The valve shaft 4 is moved up and down in the axial direction by the shaft drive unit 6. 5 is a shaft seal, 9 is a fluid outlet channel, 7
Is a casing of the entire valve device. In the above configuration, when the distance between the nozzle end face 1 'and the seal packing 2 is wide as shown in the figure, the fluid flows from the inlet 8 to the outlet 9 with almost no resistance, but the fluid flows through the valve shaft 4 in the axial direction. When the gap between the packing 2 and the nozzle end face 1 ′ is reduced by driving the flow path, the flow path resistance increases, and the flow rate of the fluid flowing therethrough decreases.
When they come into complete contact, the fluid flow is completely shut off. In general, in this type of flow control, the flow rate is proportional to the cube of the gap, so that the flow rate tends to greatly change with a small change in the gap. Therefore, it has been difficult to perform delicate control and minute precision control. For example, in a gas chromatograph or the like, accurate qualitative / quantitative measurement is difficult if the flow rate of the carrier gas cannot be controlled very precisely. Therefore, improvement of this type of control valve has been demanded.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides a flow control valve capable of finely and minutely controlling a flow rate only by a normal displacement of a valve shaft. Things.

[0004]

According to the present invention, in order to achieve the above object, one of the contact surfaces between the nozzle end face and the sealing elastic body is formed on a slope.

[0005]

The flow control characteristics can be greatly improved by a very simple structural improvement, and more precise flow control has become possible.

[0006]

An embodiment of the present invention will be described below with reference to FIG. A nozzle 1 and an axially movable sealing gasket 2 are disposed inside a casing 7 so as to face each other, and a fluid inlet flow path 8 and a fluid outlet flow path 9 are integrally formed with the casing 7. The seal packing 2 held by the packing holding portion 3 is made of rubber and can be elastically deformed, and its end face 2 ′ is formed perpendicular to the axis of the valve shaft 4. The end face 1 ′ of the nozzle 1 integrally formed at the lower part of the casing 7 is a face inclined with respect to the axis of the valve shaft 4.
The valve shaft 4 is moved in the axial direction by driving of a shaft driving unit 6 installed outside the casing 7. When the valve shaft 4 is moved in the direction of the nozzle 1, the sealing gasket 2 comes into contact with the inclined end face 1 'of the nozzle 1 from the portion 1a closest to the sealing gasket 2 and finally comes into contact with the entire end face 1'. 1 (b)
The flow path 8 is fully closed as shown in FIG. When the valve shaft 4 is gradually moved in the direction opposite to the nozzle 1, a part of the opening at the end face 1 'of the flow path 8 opens as shown in FIG. 1C, and the fluid flows through this part. As the valve shaft 4 moves, the seal packing 2 gradually moves away from the lowest portion 1b of the inclined end surface 1 'of the nozzle 1. As a result, the size of the opening of the flow path 8 gradually increases with respect to the displacement of the valve shaft 4, so that the flow rate of the fluid changes minutely with respect to the displacement of the valve shaft 4. This allows precise flow control. 5 is a shaft seal packing. In FIG. 1, the fluid enters through the flow path 8 and flows out of the flow path 9, but may enter the flow path 9 and flow out of the flow path 8.

As a modification of the present invention, as shown in FIG. 2, the end face 22 'of the seal packing 22 is inclined with respect to the axis of the valve shaft 4, and the end face 21' of the nozzle 21 is formed horizontally. Even so, the size of the opening of the flow path 8 gradually changes with respect to the displacement of the valve shaft 4, so that the same effect as that of the structure of FIG. 1 can be obtained.

[0008]

As described above, according to the present invention, since the flow rate does not change significantly with respect to the minute displacement in the axial direction of the valve shaft,
The pressure or flow rate of the fluid can be controlled precisely and stably.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a flow control valve according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a valve seal portion of a flow control valve according to another embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional flow control valve.

[Explanation of symbols]

1. Nozzle 2. Seal packing 3.
Packing holding part 4 ... Valve shaft 6 ... Shaft driving part 7 ...
Casing 8, 9 ... flow path

Claims (1)

(57) [Claims] 1. A valve device for controlling a flow rate by closing an open end surface of a nozzle constituting one end of a flow path via a movable valve shaft provided with a sealing elastic member at a tip thereof. A flow control valve, wherein one of an abutting surface of an end surface and an elastic body for sealing is formed on a slope.