JP2008138733A - Non-return valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-return valve for supporting valves at an extremely weak spring constant using shape-memory alloys of rust-proofing Nickel-Titan (Ni-Ti) alloy or the like. <P>SOLUTION: In a non-return valve device having a structure which elastically pressure-welds a globe as a valve element to the valve seat which is the entrance side of a fluid, three or more shape-memory alloys made linear members are erected from the exit side to the entrance side so as to be located at regular intervals in the periphery of the central axis of the valve seat, and each linear member keeps the inward curving part bent to the center as it goes to the top end from a base fixed end and the outward curving part bent by the curve so as to depart from the center, following the inward curving part. The non-return valve is characterized in that the globe is supported so as to pressure-weld to the valve seat elastically by the outward curving part of the three or more linear members. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a check valve that is attached to a pipe and allows a unidirectional flow of fluid, but stops the flow in the opposite direction, and in particular, a shape memory alloy suitable for inlet and outlet pipes of fluid machines, small pumps, etc. Relates to a check valve using

2. Description of the Related Art Conventionally, a check valve using a shape memory alloy is shown in FIG.
This check valve is a check valve attached to the steam piping system, and an annular groove is formed at the inner end of the inlet side member 1 on the outer periphery of the valve seat 5, and between this groove and the front surface of the valve body 7. A coil-shaped shape memory alloy 12 is disposed as a temperature responsive member. The shape memory alloy 12 is deformed according to the temperature of the fluid. The deformation force of the shape memory alloy 12 at a low temperature is formed slightly stronger than the weight of the disc-like valve body 7 and the elastic force of the coil spring 9. FIG. 2 shows that the fluid temperature is below a predetermined value, the shape memory alloy 12 has undergone martensitic transformation from the parent phase to the martensite phase, has a long shape that has been stretched and memorized, and the valve element 7 is attached to the coil spring 9. It is energized in the valve opening direction against the force.
When the fluid temperature becomes a predetermined temperature or more, the shape memory alloy 12 reversely transforms from the martensite phase to the parent phase and becomes a short shape that is contracted and memorized. No longer involved in movement. If the fluid pressure at the inlet 3 is higher than that at the outlet 4, the valve element 7 compresses the coil spring 9 and displaces it toward the outlet side, thereby opening the valve. When the fluid pressure at the outlet 4 becomes higher than that at the inlet 3, the valve body 7 is displaced by the action of the fluid pressure and the coil spring 9, and is displaced toward the inlet side to be in airtight contact with the valve seat 5. For this reason, since the coil spring made of a shape memory alloy as a temperature responsive member at a low temperature greatly opens the valve body, low-temperature water and air can be quickly discharged in a short time, and the startup time can be shortened.

JP-A-6-11057

The above-described conventional check valve can be restored to its original shape only by heating when it is used in the martensite phase lower than the martensite transformation start temperature (Ms point) or in the two-phase region of martensite phase + austenite phase. It uses the shape memory effect to recover.
Those using such a shape memory effect cannot be used without temperature change. In addition, since the shape memory alloy is used in the shape of a coil spring, it cannot be used for a small check valve or the like that must support the valve with a very weak spring constant.

  On the other hand, no small check valve exhibits a stable check valve effect from low pressure to high pressure because of its simple structure.

  An object of the present invention is to provide a check valve that can support a valve with a very weak spring constant using a shape memory alloy such as a nickel titanium (Ni-Ti) alloy resistant to rust.

The principle of the present invention is that the superelastic effect of a shape memory alloy such as a nickel titanium (Ni-Ti) alloy, that is, deformation of an alloy in the parent phase causes stress-induced martensitic transformation following the elastic deformation. The deformation continues even without increasing the load, but this deformation strain utilizes the property that when the stress is removed, it returns to its original state without heating.
In order to achieve the above object, the check valve of the present invention is a check valve device having a structure in which a spherical body as a valve body is elastically pressed against a valve seat on the fluid inlet side and made of three or more shape memory alloys. The linear members are erected from the fluid outlet side to the inlet side so as to be positioned at equal intervals around the central axis of the valve seat, and each linear member is directed toward the center from the base fixed end to the tip. An inwardly curved portion bent into a curved shape, and an outwardly curved portion bent in a curved shape so as to be away from the center following the inwardly curved portion, and the sphere is formed into three or more linear shapes. It is characterized in that it is supported so as to be elastically pressed against the valve seat at the outward curved portion of the member.
The check valve of the present invention is characterized in that the linear member is formed of a nickel titanium alloy.

The present invention has the following excellent effects.
(1) Since the linear member can be used as a spring without using a coil spring by utilizing the superelastic effect of the shape memory alloy, even from a low pressure to a high pressure even in a small check valve having a simple structure. A check valve that exhibits a stable check valve effect can be obtained.
(2) The valve body can be supported with an extremely weak spring constant.
(3) Since the spring is shape-transferred to an arbitrary shape of shape memory alloy, it is easy to manufacture.
(4) The flow path is not blocked like a coil spring arranged around the flow path.
(5) By adopting a nickel titanium alloy as the shape memory alloy, an oxide film is formed on the surface, so that it can be used for a long time even if used in an environment such as water.

  The best mode of a check valve according to the present invention will be described below with reference to the drawings based on the embodiments.

FIG. 1 is a cross-sectional view of a check valve according to the present invention.
The casing 20 that houses the check valve is connected to an inlet pipe 21 on the fluid inlet side and an outlet pipe 22 on the fluid outlet side, and a side plate 23 is detachably provided by a fixing member such as a bolt.
A valve seat 24 is formed on the fluid inlet side of the casing 20, and a sphere 25, which is a valve body, is arranged on the valve seat 24 so as to be freely contacted and separated. In order to increase the sealing degree of the spherical body 25 and the valve seat 24, it is desirable to form the valve seat 24 from rubber.

The spherical body 25 is supported so as to be elastically pressed against the valve seat 24 by a spring made of a shape memory alloy having a superelastic effect such as a nickel titanium (Ni—Ti) alloy. The spring is composed of three or more linear members 26 made of a shape memory alloy, and each linear member 26 is arranged around the central axis xx of the valve seat 24 from the fluid outlet side to the inlet side. It stands up so that it may be located at equal intervals. FIG. 1 shows a state in which four linear members 26 are arranged at equal intervals, and the three linear members 26 can be seen.
Each linear member 26 has a base 27 fitted into a mounting hole of the outlet side member 28 of the casing 20 and fixed by means such as welding, and the central axis x− of the valve seat 24 as it goes from the base fixed end 27 to the tip. an inward curve portion 29 bent in a curve toward x, and an outward curve portion 30 bent in a curve so as to be away from the central axis xx following the inward curve portion 29. Yes. The spherical body 25 is supported so as to be elastically pressed against the valve seat 24 by the outward curved portions 30 of the four linear members 26. Note that a total of at least three or more linear members 26 are provided.

  The linear member 26 is formed of a wire made of nickel titanium (Ni—Ti) alloy having a diameter of, for example, about 0.2 mm. The sharp curve increases or decreases the cross-sectional area of the linear member. Used to transfer the shape. The outwardly curved portion 30 of the linear member 26 serves as a spring and has a structure that elastically supports the sphere 25.

FIG. 1 shows a state in which a sphere 25 that is a valve body is in close contact with the valve seat 24, and at this time, the linear member 26 is in a parent phase state.
Now, when the fluid flows in from the inlet pipe 21, pressure acts on the sphere 25, and the linear member 26 is deformed. At this time, the linear member 26 undergoes stress-induced martensitic transformation following elastic deformation, and continues the state of deformation distortion without increasing the load. For this reason, the fluid flows from the inlet pipe 21 to the outlet pipe 22.
Next, when the fluid tries to flow backward from the outlet pipe 22 toward the inlet pipe 21, the sphere 25 moves in the direction of the valve seat 24, so that the stress acting on the linear member 26 is removed. For this reason, the deformation distortion of the linear member 26 is eliminated, and the original shape is instantaneously restored without heating. This is because the parent phase is in a stable temperature range, and thus is transformed back to the parent phase as it is. Accordingly, the sphere 25 is in close contact with the valve seat 24 and blocks the fluid flow.

It is the figure which showed the cross section of the non-return valve which concerns on embodiment of this invention. It is sectional drawing explaining the conventional non-return valve using a shape memory alloy.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Casing 21 Inlet piping 22 Outlet piping 23 Side plate 24 Valve seat 25 Sphere which is a valve body 26 Linear member made from shape memory alloy 27 Base fixed end of linear member 28 Outlet side member of casing 29 Inward curved portion 30 Outward direction Curve part

Claims (2)

  In a check valve device having a structure in which a spherical body as a valve body is elastically pressed against a valve seat on the fluid inlet side, three or more linear members made of shape memory alloy are directed from the fluid outlet side to the inlet side. An inwardly tangential curved portion bent in a curved shape toward the center as it goes from the base fixed end to the distal end, standing upright so as to be positioned around the central axis of the valve seat; And an outward tangent curve portion bent in a curved shape so as to be away from the center following the inward tangent curve portion, and the sphere is attached to the valve seat at the outward tangent curve portion of three or more linear members. A check valve characterized by being supported so as to be elastically pressed. 2. The check valve according to claim 1, wherein the linear member is made of a nickel titanium alloy.

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