JPH0115958Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a structure for fixing a diaphragm used as a pressure receiving element such as a differential pressure transmitter or a range spring to a device body.

As is well known, in differential pressure transmitters, pressure transmitters, etc., elastically deformable diaphragms are used as pressure receiving elements to receive the pressure of the fluid to be measured, range springs to detect the pressure to be measured, etc. It is being

As an example of a device using this type of diaphragm, FIG. 1 shows a semiconductor differential pressure transmitter. To explain the figures, reference numeral 1 is the main body, 2a and 2b are pressure receiving diaphragms, 3 is a center diaphragm, and 4 is a center diaphragm.
is a semiconductor pressure sensitive element.

The main body 1 consists of a cylindrical body 1a and a neck 1b bored in the outer periphery of the body 1a.
The body portion 1a includes a first member 5 having a recess 5a having a circular cross section formed in one side thereof, and a second member 6 fitted into the recess 5a. These first
Wave-like recesses 5b, 6b are formed on opposing surfaces of the second members 5, 6, respectively, and the center diaphragm 3 is formed in these recesses 5b, 6.
b, and is fixed to the main body 1 at its peripheral edge. A pair of pressure receiving chambers 8a and 8b partitioned by a center diaphragm 3 are formed inside the body portion 1a.

Furthermore, concave wavy nests 9a and 9b are formed on both sides of the body 1a, and the pressure receiving diaphragms 2a and 2b are fixed to the main body 1 at their respective peripheral edges so as to close these nests 9a and 9b. has been done. And the pressure receiving diaphragm 2a,
The insides of the nests 9a, 9b closed by the nests 2b are communicated with the pressure receiving chambers 8a, 8b through pressure guiding holes 10a, 10b, respectively.

Further, inside the neck portion 1b, a semiconductor pressure sensitive element 4 is provided as a pressure detection element, and a pair of pressure sensitive chambers 12a and 12b partitioned by the semiconductor pressure sensitive element 4 are formed. These pressure sensing chambers 12a, 12b are communicated with the pressure receiving chambers 8a, 8b, respectively, through pressure guiding paths 13a, 13b formed in the main body 1.

A pressure receiving diaphragm 2a inside the main body 1,
The space closed by 2b is filled with an incompressible sealed fluid as a pressure transmission medium.

A conventional diaphragm fixing structure in the above differential pressure transmitter will be explained using the center diaphragm 3 as an example. FIG. 2 is an enlarged view of a portion A surrounded by a two-dot chain line in FIG. As shown in this figure, the center diaphragm 3 is in close contact with the peripheral edge of the recess 5b of the first member 5, and
A predetermined distance outward from the edge is fixed by electron beam welding or the like.

Therefore, in the differential pressure transmitter described above, when the measured pressures P _H and P _L are applied to the pressure receiving diaphragms 2a and 2b, these pressures P _H and P _L are applied to both sides of the center diaphragm 3 via the sealed fluid. Each is transmitted. As a result, the center diaphragm 3 is elastically deformed by an amount corresponding to the pressure difference between the pressures P _H and _PL , and the pressures P _H and _PL are applied to the interiors of the pressure receiving chambers 8a and 8b, respectively. At the same time, the pressure P _H ,
P _L is transmitted to both sides of the semiconductor pressure sensing element 4 through the pressure guiding paths 13a and 13b, and the pressure sensing element 4 detects the differential pressure between the pressures P _H and _PL .

By the way, the center diaphragm 3 used in the differential pressure transmitter described above is elastically deformed during the measurement operation as described above. However, according to the conventional diaphragm fixing structure, the center diaphragm 3 is attached to the first member 5 as shown in FIG.
When deforming toward the recess 5b, the fulcrum of the movement is the edge of the recess 5b (point B in the figure),
On the other hand, when deforming toward the recess 6b of the second member 6, the fulcrum becomes the welded portion (point C in the figure).
Therefore, the fulcrum of the operation of the center diaphragm 3 differs depending on the direction of displacement, resulting in a drawback that the linearity of the output of the differential pressure transmitter deteriorates when the center diaphragm 3 is displaced near the neutral position.

The present invention has been made for the purpose of eliminating the drawbacks of the conventional diaphragm fixing structure and providing a fixing structure in which the fulcrum of the diaphragm displacement operation is constant regardless of the direction of displacement.

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

FIG. 3 is a diagram showing an embodiment in which the present invention is applied to the center diaphragm 3 of the differential pressure transmitter shown in FIG. 1. In this figure, the same components as in FIGS. 1 and 2 are given the same reference numerals and their explanations will be omitted.

The difference between the fixing structure shown in FIG. 3 and the structure shown in FIG. 1 is fixed by welding.

The seal plate 30 is annularly formed of metal, and its inner peripheral edge serves as a fixed edge 30a for fixing the center diaphragm 3, and the opening edge of the recess 5b of the main body 1 A thin collar portion 31 is formed on the inner circumferential edge thereof and extends inward from the fixed end edge portion 30a.

This seal plate 30 has sufficient rigidity, and as shown in FIG. arranged,
From the outer surface of the seal plate 30 toward the main body 1,
Moreover, it is fixed to the main body 1 together with the center diaphragm 3 by electron beam welding along the fixed end edge 30a.

During such a welding and fixing operation, the flange portion 31 has the effect of preventing the inner peripheral portion of the seal plate 30 from sagging during welding and the effect of preventing the center diaphragm 3 from being directly irradiated with the electron beam. It will be done.

According to the diaphragm fixing structure of this embodiment, the fulcrum of the displacement movement of the center diaphragm 3 is sandwiched between the opening edge of the recess 5b of the main body 1 and the fixed end edge 30a of the seal plate 30. This will be clearly defined as a part of the

Therefore, in the differential pressure transmitter to which this embodiment is applied, the center diaphragm 3 operates stably near its neutral position, and stable output characteristics can be obtained.

In addition, the action of the flange portion 31 prevents welding sag from occurring and prevents direct irradiation of the electron beam to the center diaphragm 3, so the welding position should be placed as close to the fulcrum of the center diaphragm 3 as possible. As a result, high fixing strength can be obtained and the fulcrum position can be more clearly defined.

In the above embodiment, the present invention is applied to the center diaphragm 3 of a differential pressure transmitter, but it can also be applied to pressure receiving diaphragms 2a and 2b fixed to the side of the main body 1. Needless to say, the present invention can be applied not only to differential pressure transmitters but also to pressure transmitters and other devices using diaphragms.

As explained above, the diaphragm fixing structure according to the present invention fixes the diaphragm so that the shape of the peripheral edge of the opening of the device body and the shape of the fixed edge match the shape of the opening of the hole or recess. and a seal plate having a thin-walled flange extending inward from the fixed end edge on the inner periphery thereof, and the seal plate and the diaphragm are attached to the main body. Since the seal plate is fixed along the fixed edge portion by electron beam welding, the following excellent effects can be achieved.

The fulcrum of the displacement movement of the diaphragm is determined at a position sandwiched between the opening of the recess or hole and the fixed end edge of the inner periphery of the seal plate, and therefore the fulcrum is determined regardless of the direction of displacement of the diaphragm. hand,
Operation is stable even near the neutral position.

As a result, highly accurate output characteristics can be obtained in devices such as differential pressure transmitters to which the present invention is applied.

In addition, due to the action of the flange formed on the inner circumference of the seal plate, the welding and fixing position of the seal plate, diaphragm, and main body can be moved closer to the fulcrum of the diaphragm, thereby improving the fixing strength. Furthermore, the rigidity required for the seal plate can be reduced, making it possible to make the seal plate thinner.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a differential pressure transmitter as an example of a device using a diaphragm, and FIG. 2 is an enlarged view of a portion A surrounded by a two-dot chain line in FIG.
FIG. 3 is a sectional view of a main part showing a conventional fixing structure, and FIG. 3 is a sectional view of a main part showing an embodiment of the present invention. 1... Main body (equipment main body), 3... Center diaphragm (diaphragm), 5b, 6b... Recessed part,
30...Seal plate, 30a...Fixed edge portion, 31...Brim portion (thin brim portion).

Claims (1)

[Scope of utility model registration request] A diaphragm fixing structure in which a diaphragm arranged to close an opening of a hole or a recess bored in a device main body is fixed to the main body along a peripheral edge of the opening, wherein the diaphragm is formed such that the shape of the peripheral edge of the opening and the fixed edge match the shape of the opening of the hole or recess, and that the inner circumference is formed so that the shape of the fixed edge is inward from the fixed edge. and a seal plate having a thin flange extending toward the main body, and the seal plate and the diaphragm are fixed to the main body by electron beam welding along the fixed edge of the seal plate. A fixed diaphragm structure characterized by: