JPS5840059B2 - pinch valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve that is attached to a fluid piping for liquid or gas to open and close a fluid passage to control the flow of fluid.

(Subject of the Invention) The present invention forms a part of a fluid passage with a tube made of a flexible material such as rubber or synthetic resin, and bends the flexible tube with an appropriate operating means to control the fluid passage. Related to pinch valves that open and close.

The present invention relates in particular to a pinch valve that applies fluid pressure to the outer periphery of a flexible tube to bend the tube, and particularly to a pinch valve that uses the pressure of a controlled fluid as an operating force.

(Prior Art and Problems) In the pinch valve disclosed in JP-A-50-122727, a liquid-sealed chamber is formed around the outer periphery of a flexible tube that forms part of a fluid passage. Part of the wall is made of a diaphragm (variable wall), and the controlled fluid of the fluid passageway is guided outside the diaphragm.

Therefore, the pressure of the controlled fluid acts on the diaphragm, and the pressure in the liquid-tight chamber through the diaphragm becomes equal to the pressure of the controlled fluid, so the same amount of pressure always acts on the flexible tube from the inside and outside. There is.

For this reason, it is possible to bend the flexible tube with a small operating force.

However, in the pinch valve described above, the operating fluid is applied to the piston, and the displacement of the piston directly pushes the diaphragm to increase the pressure in the liquid-tight chamber and bend the flexible tube, so it has the following drawbacks: be.

In other words, when the operating fluid is applied to the piston, the pressing force of the piston changes depending on the pressure of the operating fluid, and the operating force may be insufficient to close the valve. Excessive force may be applied to the tube or diaphragm, causing it to break.

(Technical Problem of the Present Invention) A technical problem of the present invention is that even if the pressure of the operating fluid applied to the piston changes, the operating force against the bending resistance of the flexible tube itself remains almost constant. , to make it act on the variable displacement wall.

(Technical means of the present invention) The technical means of the present invention taken to solve the above problems are as follows.

In other words, (a) a sealed space is formed outside the variable displacement wall that covers a part of the wall of the liquid-sealed chamber, and (b) the output shaft of the piston, which has a stroke limit in the direction of the sealed space, is connected to the wall of the sealed space. The flexible tube is disposed airtightly and slidably through the piston, and a passage is provided through the output shaft of the piston to communicate the interior of the cylinder with the sealed space, and the flexible tube is inserted at the stroke limit position of the piston. A spring with a predetermined strength sufficient to bend and close the
It is interposed between the output shaft of the piston and the variable displacement wall, and (e) introduces the controlled fluid into the cylinder as the operating fluid for the piston.

(Effect of the above means) The above means works as follows.

When the controlled fluid in the fluid passage is introduced into the cylinder and acts on the piston, a part of the controlled fluid introduced into the cylinder reaches the sealed space through the passage provided in the output shaft of the piston, causing a variable exerts fluid pressure on the wall.

Therefore, the pressure in the liquid-tight chamber is equal to that of the controlled fluid,
Equal pressure acts on the inside and outside of the flexible tube.

The piston is also displaced to its stroke limit in a direction in which its output shaft compresses the spring.

At this time, since the sealed space outside the variable displacement wall communicates with the inside of the cylinder through the passage provided in the output shaft of the piston, the pressure in the sealed space does not increase.

Therefore, due to the displacement of the piston, the force acting on the variable displacement wall increases by the compression reaction force of the spring.

In this way, regardless of the pressure of the operating fluid acting on the piston, an approximately constant force is always exerted on the variable displacement wall due to the compression reaction force of the spring.

(Special effects of the present invention) The present invention has the following unique effects.

When the same fluid pressure is always applied to the inside and outside of the flexible tube, the flexible tube can be bent with a small external force that is sufficient to overcome its elastic restoring force.

Then, by applying the minimum force necessary for bending,
This is preferable also from the viewpoint of the lifespan of the flexible tube and diaphragm.

In the present invention, the force acting on the flexible tube is determined by the compression reaction force of the spring at the piston's stroke limit position, regardless of the pressure of the operating fluid, and the strength of the spring is designed to the minimum necessary value. be done.

In the case where the displacement of the piston is directly applied to a variable displacement wall such as a diaphragm, it is necessary to adjust the fluid pressure acting on the piston to a predetermined value.

For this purpose, it is necessary to prepare a fluid source whose pressure is regulated, or, in the case of a fluid source whose pressure fluctuates, to regulate the pressure using a pressure reducing valve or an accumulator.

In the present invention, since fluctuations in fluid pressure do not affect the variable displacement wall, the controlled fluid can be used as the operating pressure source.

(Example) An illustrated embodiment showing a specific example of the present invention will be described.

1 is the main body.

The main body 1 has a substantially cylindrical shape and has shoulders at both ends.

A side wall of the main body 1 is provided with an annular protruding wall 2.

The upper end (in the figure) of the annular projecting wall is provided with a shoulder.

The inside of the main body 1 and the inside of the annular projecting wall 2 are communicated through a through hole 3.

A flexible tube 5 having flanges 4 at both ends is disposed inside the main body 1.

Both flanges 4 fit into shoulders at both ends of the main body 1.

Reference numeral 6 denotes end members screwed onto both ends of the main body 1, and the collar 4 of the flexible tube 5 is hermetically fixed between the shoulder portions at both ends of the main body 1.

The end member 6 is provided with an inlet 6' and an outlet 6'' coaxially and with the same diameter as the inner diameter of the flexible tube 5.

7 indicates a fluid passage for the fluid to be controlled.

A cylinder member 9 is fixed to the shoulder portion of the annular projecting wall 2 of the main body 1, sandwiching the edge of the flexible membrane 8.

A liquid-tight chamber 10 is formed on the outside of the flexible tube 5 and under the flexible membrane, and is sealed against water or oil.

The cylinder member 9 has a small diameter portion forming a cylindrical space 11;
It consists of a large diameter flange having a step around the outer periphery.

A through hole 12 communicating with the cylindrical space 11 is located at the center of the large diameter flange.
is drilled.

A cylinder member 13 is fixed to a stepped portion around the outer periphery of the large-diameter flange.

The cylinder member 13 forms a large diameter cylindrical space 14 between the cylinder member 13 and the upper end surface of the large diameter flange.

A large-diameter piston 16 is disposed within the cylindrical space 14 and slides on the inner circumferential wall of the space 14 in an airtight manner via an OIJ song 5.

The lower part of the piston 16 in the cylindrical space 14 is always open to the atmosphere through the through hole 17.

- An opening 18 is provided above the piston 16 in the force testing space 14.

A piston rod 19 of the piston 16 is fitted into the through hole 12.

20 is an O-ring backing for allowing the fitting to slide airtightly.

A through hole 21 is bored in the center of the piston rod 19.

A piston rod 23 of a piston 22 that is in contact with the upper surface of the flexible membrane 8 is loosely fitted into the through hole 21 .

A coil spring 24 is arranged around the piston rod 23 between the upper surface of the piston 22 and the lower end surface of the piston rod 19.

A vent hole 25 is provided in the center of the piston rod 23, and communicates the upper part of the piston 16 in the space 11 with the upper part of the flexible membrane 8 in the space 11 through an orifice 26.

When the piston 16 is at its lowest position, the coil spring 24
It exerts compressive elastic force to the extent that it can counteract the bending resistance of the flexible tube 5, which has the same internal and external pressures.

27 is a passage 2 that communicates the opening 18 and the inlet side fluid passage 7.
A first switching valve located at 8 connects the opening 18 to the atmosphere.
position and a second position communicating with the inlet fluid passageway 7.

Next, the operation of the above embodiment will be explained.

When the switching valve 27 is in the first position shown, the opening 18 is in communication with the atmosphere.

Therefore, the upper and lower sides of the piston 16 are open to the atmosphere, and the coil spring 24 is in its natural state.

The upper part of the flexible membrane 8 in the cavity 11 is also open to the atmosphere.

Therefore, the pistons 16, 22 and the coil spring 24
Ignoring its own weight, the inside of the liquid-sealed chamber 10 is not pressurized, so the flexible tube 5 is expanded by the pressure inside the fluid passage 7 and is in an open state.

Next, the switching valve 27 is switched to the second position to communicate the opening 18 with the artificial fluid passageway 7.

At this time, the fluid pressure in the fluid passage 7 passes through the vent hole 25 and the orifice 26 and acts on the upper surface of the flexible membrane 8.

Through this process, the pressure inside and outside of the flexible tube 5 becomes the same.

Additionally, fluid pressure from opening 18 acts on piston 16 and compresses spring 24 via piston rod 19.

The compression reaction force of the spring 24 further pressurizes the liquid in the liquid-sealed chamber 10, causing the flexible tube 5 to bend.

The elastic force of the spring 24 when fully compressed is designed to be the minimum amount sufficient to bend the flexible tube and close the fluid passage under the same internal and external pressure conditions. genital tract 5
closes the fluid passage 7 by receiving the minimum necessary external force.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view of a pinch valve according to an embodiment of the present invention. 1 is a main body, 5 is a flexible tube, 7 is a fluid passage, 8 is a flexible membrane, 10 is a liquid-tight chamber, 16 is a piston, 18 is an opening, 1
9 is a piston rod, 22 is a piston, 23 is a piston rod,
24 is a coil spring, 25 is a ventilation hole, 27 is a switching valve, and 28 is a passage connecting the switching valve 27 with the opening 18 and the fluid passage 7.

Claims (1)

[Claims] 1 Form a liquid-sealed chamber surrounding the outer periphery of a flexible tube that forms part of a fluid passage, form a sealed space outside a variable displacement wall that forms part of the wall of the liquid-sealed chamber, and form a sealed space in the direction of the sealed space. The output shaft of the piston, which has a stroke limit, is disposed airtightly and slidably through the wall of the sealed space. A spring with a predetermined strength sufficient to bend and close the flexible tube at the stroke limit position is interposed between the output shaft of the piston and the variable displacement wall, and a controlled fluid is used as the operating fluid of the piston. Pinch valve introduced into the cylinder.