JPS6018678A - Pressure-response valve - Google Patents

Abstract

PURPOSE:To prevent a diaphragm from being deformed by welding by disposing a circular groove between the inner periphery of a flange for fixing a diaphragm and the outer peripheral end of a flange joined to a casing by fusing. CONSTITUTION:A circular groove 24c is formed at the substantially central part of a diaphragm flange 24a of a diaphragm 24. The inside 24d of the circular groove 24c is fixed to the lower surface of an upper casing flange 22a at the upper surface of an inner flange 23c of an engaging portion 23b of a lower casing flange 23a. Though at the time of welding, the diaphragm 24a contracts inward, the circular groove 24c contracts radially, so that stress strain is prevented from being transmitted to the inside 24d of the circular groove.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in pressure-responsive valves such as safety valves used for refrigerant control in refrigeration systems used in air conditioners and the like.

Construction of a conventional example and its problems A safety valve shown in FIG. 1 will be described as a conventional pressure-responsive valve of this type.

1 is the safety valve, upper casing 2. Lower casing 30
A diaphragm 4 is provided in between, and each outer peripheral end is hermetically joined by arc welding or the like to form an outer shell 5. A valve device 7 is provided in the valve chamber 6 formed by the diagram 4 and the lower casing 3, and has an inlet pipe 8 communicating with the valve chamber 6 and an outlet pipe 9 on the side opposite to the valve chamber 6 of the valve device 70. There is. An adjustment chamber 10 formed by the diaphragm 4 and the upper casing 2 includes a bias spring 11 and an adjustment screw 12. In other words, valve chamber 6. The pressure P, the effective area A of the diaphragm 4, the biasing force F1 of the bias spring 11, and the valve chamber 6 of the diaphragm 4
In relation to the repulsive force R to the side, P ) (F + R)/
A, the valve device 7 is opened and the inlet pipe 8 → valve chamber 6 is opened.
The refrigerant flows from → valve device 7 → outlet pipe 8.

In this type of pressure-responsive valve, the diaphragm 4 and the upper casing 2. Thermal expansion occurs in the welded portions of both the lower casing 3. As is well known, the diaphragm 4 is heat-treated, and also.

Since the material of the lower casings 2 and 3 is different, as shown in Fig. 2, the state during welding (double-dashed line in Fig. 2) is the same as before welding (
2), the outer peripheral ends of the upper and lower casings 2 and 3 are shaped to protrude from the outer peripheral end of the diaphragm 4. In this state, the upper and lower casings 2 and 3 and the diaphragm 4 are melted and integrally formed by arc welding. Next, we will explain what happens after welding is completed.○ As shown in Figure 3, the shape after welding (solid line in Figure 3) is 2.3 mm larger than the shape before welding (dashed line in Figure 3). returns to the same shape as before welding, but during welding,
The diaphragm 4il''i, whose outer circumferential ends are integrally melted in a state with little thermal expansion, undergoes the same amount of contraction as the upper and lower cages 2 and 3.Therefore, the diaphragm 4 undergoes stress strain in the inner circumferential direction, The shape of the bead portion 4a of the diaphragm 4 that undergoes pressure deformation changes, and the center surface 4b of the diaphragm 4 changes downward (as shown by the dashed line in Figure 3) from the position before welding (solid line in Figure 3).The amount of change due to this welding. X is on top.

It varies due to subtle fluctuations in the thermal expansion coefficient of the lower casings 2 and 3, plate thickness, arc energy amount, etc., and normal material management 9
In condition management, etc., the amount of change x ('j, 0.1 mm to 0.
There will be a variation of about 4 mm. Therefore, if the displacement of the diaphragm 4 required to open and close the valve device 7 of the safety valve 1 is designed to be 0.6-, the actual absolute displacement of the diaphragm 4 will vary from 0.6 to 0.8. In order to guarantee reliability, it is necessary to use a diaphragm 4 with a very high displacement, or to control the material of the upper and lower casings 2 and 3, arc welding conditions, etc. very strictly. I had a problem.

Purpose of the Invention In view of the above-mentioned problems, the present invention prevents changes in the diaphragm due to welding even if variations in component parts or welding conditions occur, and enables prevention of excessive quality of the diaphragm and easy assembly. It is intended to.

Structure of the Invention In order to achieve the above object, the pressure-responsive valve according to the present invention is provided with an annular groove for absorbing stress strain between the inner peripheral side of the flange that fixes the diaphragm and the outer peripheral end of the flange that is fused and joined to the casing, and is welded. This prevents the stress strain due to thermal expansion from reaching the diaphragm's speed at 0.0.
Reference numeral 021, which will be explained according to FIG. 2, is a safety valve that is a pressure-responsive valve. 22 is an upper casing, 23 is a lower casing, and 24 is a diaphragm, each having an upper casing flange 22a,
Lower casing flange 23a.

The outer peripheral end of the diaphragm flange 24a is melted and integrally formed by arc welding. A threaded portion 25 is formed at the upper center of the upper casing 22, and an adjustment screw 27 whose lower surface abuts the upper end of the spring A26 whose lower end abuts the upper surface of the center 24b of the diaphragm 24 is screwed together. The inside of the adjustment chamber 2'8, which is composed of the casing 22 and the diaphragm 24, has a through hole 2 provided in the adjustment screw 2.
Atmospheric pressure acts via 7a. On the other hand, a valve device 30 is provided in a valve chamber 29 composed of a lower casing 23 and a diaphragm 24 . 31 is a valve seat, 32 is a valve body,
33 is a spring B, the valve seat 31 is joined to the lower casing, and communicates with the outlet pipe 34. Spring B3
3 engages the lower end with the outer periphery of the valve seat 31 and the upper end with the valve body 32,
The upper surface of the valve body 32 is brought into contact with the lower surface of the center 24b of the diaphragm 24. Further, the lower casing 23 is provided with an inlet pipe 35 open to the valve chamber 29. Therefore,
When the internal pressure of the valve chamber 29 exceeds the set pressure adjusted by the spring A26, the diaphragm 24 is displaced upward,
The valve device 30 is opened, allowing flow from the inlet pipe 35 to the outlet pipe 34. In addition, 36 is a stopper,
It is provided between the lower end of the spring A26 and the upper surface of the diaphragm center 24b, and is engaged with the upper surface of the upper casing 22 when the diaphragm 24 is displaced upward.

An annular groove 24G is formed approximately at the center of the diaphragm flange 24a of the diaphragm 24, and engages with a locking portion 23b (hereinafter referred to as groove 23b) formed approximately at the center of the lower casing flange 24a of the lower casing 23. The inner side 24d of the annular groove 24C of the diaphragm flange 24a is connected to the lower surface of the upper casing flange 22a and the lower casing flange 2.
It is fixed on the upper surface of the inner flange 23c of the groove 23b of 3a.

Next, arc welding during assembly of the safety valve, which is a pressure-responsive valve having the above structure, will be explained.

The shapes of the lower casing flange 22a, diaphragm flange 24a, and lower casing flange 23a before welding are as shown by the broken lines in Figure 5, and their outer peripheral ends are almost at the same position.If arc welding is performed in this state, Each part thermally expands due to the arc energy, and the fifth
The shape is shown by the solid line in the figure. At this time, each part has a slightly different coefficient of thermal expansion, degree of temperature rise, etc., so each outer peripheral edge is at a completely different position. Since each outer peripheral end is melted and integrated as it is, the shape after welding is completed is the shape shown by the solid line in FIG. 6. The shape after welding is different from the shape before welding (broken line in FIG. 6), and in particular, the diaphragm flange 24a, which has a small thermal expansion coefficient, has a large rate of inward contraction. The stress strain caused by this contraction causes the diamond slam flange 24a to contract inward, but the stress strain is absorbed by the annular groove 24c contracting in the radial direction.
No stress strain is transmitted on the inner side of the annular groove 24d-j. Therefore, the center surface 24b of the diaphragm 24 is not affected by heat due to welding at all, and the shape of the diaphragm 24 is exactly as it should be when it is cut. In other words, the shape after thermal expansion during welding (6th
Even if the shape after welding (solid line in Figure 6) is slightly different, the shape after welding (solid line in Figure 6)
In particular, the center surface 24b of the diaphragm 24 does not change at all from before welding, and therefore, the amount of displacement that determines the reliability of the diaphragm 24 also remains as designed.

Effects of the Invention As is clear from the above explanation, the pressure-responsive valve according to the present invention is formed by melt-welding a diaphragm having an annular groove substantially in the middle of the flange portion and the outer peripheral ends of the upper casing and the lower casing by arc welding or the like. Because of this, the annular groove absorbs the stress strain after assembly caused by the difference in thermal expansion of each part during arc welding, and the center surface of the diaphragm will not be deformed due to the heat effect of arc welding, reducing material variations. .

There is no need to consider variations in welding conditions.

In addition, since there is no deformation due to heat effects, the amount of diaphragm displacement is only a factor in component design, so there is no need to create a diaphragm with an excess margin that takes into account deformation due to heat effects, as in the past. This makes it possible to guarantee high quality assembly.

[Brief explanation of drawings]

Figure 1 is a sectional view of a safety valve, which is a conventional pressure-responsive valve.
The figure is an enlarged sectional view of the main part of Fig. 1 during welding, Fig. 3 is an enlarged sectional view of the main part of Fig. 1 after welding, and Fig. 4 is a sectional view of a safety valve showing an embodiment of the present invention. 6 is an enlarged sectional view of the main part of FIG. 4 during welding, and FIG. 6 is an enlarged sectional view of the main part of FIG. 4 after welding. 21... Pressure-responsive valve (safety valve), 22...
Upper casing, 23...Lower casing, 24.
...Diaphragm, 24a...Diaphragm flange, 24c...Annular groove, 3o...
Valve device, 23b...Locking part (concave groove), 24d...
...Inside the annular groove. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 4 21

Claims (1)

[Claims] (1) A diaphragm having a flange on its outer periphery and having an annular groove formed in the middle part of the flange, and the opening degree being adjusted by displacement of the upper casing, lower casing and the diaphragm that constitute the outplant. a valve device, one of the upper and lower casings is provided with a locking portion that engages the inner side of the annular groove, and the outer periphery of the upper and lower casings is heat-bonded on the outer side of the annular groove. Pressure responsive valve. 2) The pressure-responsive valve according to claim 1, wherein the mγ locking portion is a concave groove.