JPH052874B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a diaphragm valve using a relatively small diameter metal diaphragm used in various gas industries, analysis, medicine, biotechnology, instrumentation, etc. The present invention relates to a diaphragm used in the diaphragm valve.

[Conventional technology]

Conventionally, there is a valve using a metal diaphragm, for example, as shown in FIG. 5, disclosed in Japanese Patent Application Laid-Open No. 61-244976.

This includes a housing 10 in which a stopper seat 15 is provided on the bottom of a shallow concave stopper chamber 16 that communicates with a fluid inlet 11 and a fluid outlet 12; Ni-Ti maintains airtightness and also sits against the stopper seat 15 due to pseudoelastic deformation to block fluid.
Alloy diaphragm 17 and diaphragm 17
It consists of a spindle 18 which is disposed above the valve so as to be able to rise and fall freely and rests against the valve seat 15.
This is a fluid cut-off/opener characterized in that the diaphragm 17 is separated from the stopper seat 15 when opened by the restoring force due to the pseudoelastic characteristics of the Ni-Ti alloy diaphragm 17.

That is, the diaphragm 17 is formed using a Ni-Ti alloy, and undergoes pseudoelastic deformation at a temperature exceeding a set Af transformation temperature. Then, it is used under a temperature condition slightly higher than the Af transformation temperature, the spindle 18 is pressed downward, the diaphragm 17 is pressed against the stopper seat 15 against the pseudoelastic deformation of the diaphragm 17, and the diaphragm 17 is pushed downward due to its pseudoelastic properties. It is deformed into a bulged state and placed on the stopper seat 15 to close it. To open the diaphragm 17, when the spindle 18 is pulled upward, the recess formed by the spindle 18 in the diaphragm 17 will become Ni.
- Due to the pseudo-elastic properties of the Ti alloy, it shrinks and restores its shape to a flat plate, and is released from the stopper seat 15.

[Problem to be solved by the invention]

The disadvantages of the above fluid cut-off device are as follows.

A Ni-Ti based shape memory alloy must be used as the diaphragm 17, and this alloy's Af
Controlling the transformation temperature is difficult and expensive.

(b) Since the temperature during use of a valve changes depending on the installation location and fluid temperature, it can only be used under certain conditions.

C. Since the diaphragm 17 is deformed by directly applying a tensile force within the quasi-elastic deformation with its outer periphery clamped and fixed, a large amount of deformation cannot be obtained and only a small lift to open the valve seat can be obtained. ,
The flow resistance through which the fluid passes becomes large.

D. When the valve is closed, it is forcibly deformed by the spindle 18 against its original restored shape, so the shape memory alloy gradually loses its pseudoelastic properties and loses its restoring action over long-term repeated use. Stop working.

The present invention provides a metal diaphragm valve that can self-repeatedly restore itself without using expensive metals, has a large amount of displacement, and has good durability.

[Means to solve the problem]

The gist of the present invention is that the outer circumferential portion of a diaphragm is tightly sandwiched between the valve and the valve seat, and the load means for displacing the central portion of the diaphragm toward the valve seat is placed between the valve seat and the diaphragm. is provided on the opposite side, and the diaphragm is brought into contact with the valve seat by applying the load means, and the diaphragm self-returns to its original shape by releasing the load means to open and close the valve. The diaphragm is composed of a plurality of metal thin plates inflated into a partially spherical shell shape with a central portion having a large radius of curvature in the direction away from the valve seat, and the load-displacement characteristic of the diaphragm has a maximum value and a minimum value, and The minimum value is a metal diaphragm valve characterized by a positive load.

[Effect]

Since the present invention has the above-mentioned configuration, among diaphragms that elastically repeat themselves, the diaphragm has a load-displacement characteristic having a local maximum value and a local minimum value, that is, the load-displacement characteristic of the diaphragm is particularly It is a diaphragm that is not proportional and has a large displacement with respect to the load, which shows maximum and minimum values. For this reason, compared to a case where the load and displacement simply increase proportionally, the amount of displacement can be obtained larger with respect to the load, and since the minimum value is a positive value, it is elastically and repeatedly restored. Furthermore, the diaphragm has excellent durability because it is made of multiple thin metal plates.

Therefore, even among diaphragm valves with self-restoring force, since the load-displacement characteristics do not change proportionally, a highly durable diaphragm with a large opening/closing lift in which only the amount of displacement changes greatly can be obtained. Further, there is no need to separately provide a member for restoring the diaphragm, and the valve can be opened and closed simply by displacing the central portion of the diaphragm toward the valve seat on the side opposite to the valve seat. Therefore, it is possible to obtain a clean metal diaphragm valve that has a simple shape, has a large flow rate, and does not generate metal powder.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1 is the main body of the diaphragm valve, which is constructed as follows. An inlet 3 is formed on the left side, an outlet 4 is formed on the right side, an upward flow path 5 is formed in the center that is connected to the inlet and the flow direction is upward, and an outlet 4 is formed on the outlet side of the upward flow path 5. This forms a downward flow path 6 in which the flow direction is downward.

Further, a synthetic resin sheet 7 is attached to the upper end of the upward flow path 5. The upper part of the main body of the valve is open, and the lid 2 of the main body 1 is fitted and mounted, and a step 12 is formed at the fitting part of the main body 1 as a stopper for the fitted lid. By fitting and attaching the lid 2 to the main body 1, a fluid chamber 13 is created between the upper part of the main body 1 and the lid 2.
is formed, and this fluid chamber 13 communicates the upward flow path 5 and the downward flow path 6.

When the main body 1 and the lid 2 are fitted together, the main body 1
A diaphragm 9 made of a thin stainless steel plate is provided on the upper surface of the upward flow path 5, and its outer periphery is tightly sandwiched between the stepped portion 12 of the main body 1 and the lower surface of the outer periphery of the lid 2. This clamping is carried out by cutting a thread on the outer periphery of the upper part of the main body, and tightening the lid holding nut 10 which is threaded onto the external thread.

The diaphragm 9 is made of a plurality of metal thin plates stacked one on top of the other, and the center portion of each has a partially spherical shell shape with a large radius of curvature that bulges upward.
The lid 2 has a through hole in the center thereof, through which the valve rod 8 passes, and the lid 2 and the valve rod 8 are screwed together in this through hole. A handle 11 is detachably fixed to the upper part of the valve stem 8, and by rotating the handle 11, the valve stem 8 moves up and down.

The lowermost end surface of the valve stem 8 is in surface contact with the upper surface of the diaphragm 9, and by lowering the valve stem 8 by rotating a handle 11 fixed to the valve stem 8, the diaphragm 9 is also pushed down at the same time. The pushed down diaphragm finally comes into contact with the seat 7 attached to the upper part of the upward flow path 5, and the valve becomes fully closed. After this,
When the valve stem 8 is raised by rotating the handle, the diaphragm 9 follows the valve stem 8 and rises. That is, the diaphragm 9 opens the flow port due to its elastic force.

The shape of the diaphragm 9 causes the diaphragm 9 to follow the valve stem when the diaphragm 9 is pushed down by the valve stem 8 to a fully closed state and then the valve stem 8 is raised to open the valve. This will be explained using FIGS. 2 to 4.

FIG. 2 is a longitudinal sectional view showing the shape of the diaphragm 9 of this embodiment, which has a partially spherical shell shape with a large curvature. In FIG. 2, the radius of curvature of the diaphragm is R, the plate thickness of the diaphragm is t, and the angle formed by the straight line connecting the center of curvature of the diaphragm and both ends of the spherical shell of the diaphragm is 2β.

Next, as shown in FIG. 3, when the diaphragm 9 is pushed by the valve rod 8 with a load of PKg, the amount of displacement of the diaphragm is δmm. When the values of α expressed by the load P, the diaphragm thickness tmm, and the angle βrad are varied (when α is taken as a parameter), P
The relationship between and δ is shown in FIG. Here, α is R·β ² /t, and the thickness t of the diaphragm 9 is a thin stainless steel plate that is sufficiently smaller than the radius of curvature R of the diaphragm, and a plurality of these thin plates are stacked one on top of the other.

Each curve in Figure 4 is α=2.1 in the above equation, α
= 5.37, α = 6.27, these diaphragms 9 when a load PKg is applied to the three types of diaphragms 9
The curve in the figure shows a state in which the diaphragm is deformed to a position below the position where the outer peripheral clamping part is connected.

In the figure, α=2.1, α=5.37, α=6.27.
When a load of 5 kg is applied to each type of diaphragm, these displacement amounts δ are δ1, δ2, and δ3, respectively. Here, if the displacement amount δ of the diaphragm 9 is large, this means that the maximum displacement amount that the diaphragm 9 can displace following the valve stem 8 is large, and δ2 and δ3 have lifts that are more than twice as large as δ1. If this maximum displacement amount δ is large, it means that the flow rate can be large when the valve is fully open, and the flow resistance can be small.

In the figure, the diaphragm 9 with α=2.1 shows a proportional relationship in which the displacement δ increases as the load P increases over the entire displacement. On the other hand, α
For the diaphragm 9 with =5.37 and α=6.27, the displacement δ increases as the load P increases until the displacement δ is 0.2 mm at point A, but the displacement δ increases from point A to point B. The displacement amount δ increases with a load P smaller than the load.

Here, in the diaphragm 9 where δ=6.27, the load P is negative in the region where the displacement δ is from C to D. This means that by applying a load P to the diaphragm 9 with α=6.27 and increasing the displacement δ of this diaphragm 9, when it reaches point C where the load P becomes 0, the displacement will continue even without applying the load P. It means increasing to point D. Therefore, after exceeding point C, even if the load P is released, the displacement δ of the diaphragm 9 does not return to the original point O. That is, even if the diaphragm 9 is pushed down by the valve stem 8 when the valve is opened or closed, and then the valve stem 8 is raised, the diaphragm 9 will not follow the valve stem 8 and will no longer function as a valve.

In particular, in the present invention, the fundamental problem in valve opening/closing is that the load-displacement characteristic of the diaphragm does not have a negative region. This is called the elastic deformation region.

Therefore, when selecting the shape of the diaphragm 9, care must be taken to ensure that the amount of deformation δ is large and that the load P does not have a negative region. From the above explanation, the diaphragm 9 is suitable as a valve when α is smaller than around 5.37 and the displacement δ is large, since the lift of the valve is large and the flow resistance of the valve can be reduced. Therefore, in the present invention, a diaphragm is used in which the load-displacement characteristic of the diaphragm 9 has a maximum value and a minimum value, and the minimum value is a positive load.

Here, if α=5.4, then α=R·β ² /t=5.4. If the diameter of the clamping part that clamps the outer periphery of the diaphragm 9 in FIG. 2 is φK, then 2R・sinβ=K, so R=
K/2・sinβ, α=R・β ² /t=(K/2sinβ ² )・(β ² /t)=5
.Four
Therefore, (K/2t)・(β ² /sinβ)=5.4.

From this equation, when the diameter φK of the diaphragm clamping portion and the plate thickness t of the diaphragm 9 are determined, β is determined, and when φK and t are determined, the radius of curvature R of the diaphragm 9 that follows the valve stem 8 can be determined.
In this embodiment, a sheet 7 made of synthetic resin or the like is attached to the upper end of the upward flow path 5. However, the diaphragm 9 may be coated with a synthetic resin or the like, and the upper end portion of the upward flow path 5 may be formed into a protruding valve seat shape with the main body made of metal. Further, the valve stem 8 may be driven by pneumatic pressure or magnetic force.

The diaphragm valve of this example has a particularly large displacement among diaphragms that have the property of self-elastic return, so we used a diaphragm valve with a large opening/closing lift that can open and close following the valve stem, a large flow rate, and a small flow resistance. You can get it. In addition, the diaphragm has good durability and there is no need to provide a spring or the like to return the diaphragm, so a clean valve without the generation of frictional metal powder can be obtained.

〔Effect of the invention〕

The diaphragm valve of the present invention is a diaphragm valve that can have a particularly large displacement amount among diaphragms that have the property of self-elastic return. For this reason, the opening/closing lift that can be opened and closed following the valve stem is large,
A diaphragm valve with a large flow rate and low flow resistance can be obtained. In addition, the diaphragm has good durability, and since there is no need to provide any extra members or structures for returning the diaphragm, a clean valve can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of the present invention when the valve is open, Fig. 2 is a longitudinal sectional view of the diaphragm, Fig. 3 is a longitudinal sectional view when the diaphragm is being pushed down by the valve stem, and Fig. 4 is a longitudinal sectional view when the valve is open. The figure shows the relationship between the load applied to the diaphragm and the amount of displacement, and FIG. 5 is a longitudinal cross-sectional view of a conventional diaphragm valve. Explanation of symbols, 1...Main body, 2...Lid, 5...Upward flow path, 8...Valve stem, 9...Diaphragm, P...Load,
δ...Displacement.

Claims (1)

[Scope of Claims] 1. The outer peripheral part of the diaphragm is placed opposite to the valve seat of the valve with the outer circumferential part of the diaphragm being sandwiched between the valve and the valve, and a load means for displacing the central part of the diaphragm toward the valve seat is applied to the diaphragm. In a diaphragm valve that is provided on the opposite side of the valve seat, the diaphragm is brought into contact with the valve seat by application of the load means, and the diaphragm self-returns to its original shape by releasing the load means to open and close the valve. The diaphragm is composed of a plurality of metal thin plates inflated into a partially spherical shell shape with a central portion having a large radius of curvature in a direction away from the valve seat, and the load-displacement characteristic of the diaphragm has a maximum value and a minimum value. A metal diaphragm valve characterized in that the minimum value is a positive load.