JPH11344403A - Differential pressure gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure of an overpressure protective mechanism in the space of a capsule body to a pressure receiving sensor section by providing a center diaphragm and seal diaphragms in the space of the capsule body in such a way that the seal diaphragms hold the center diaphragm between them, and introducing pressures to the pressure receiving sensor section from the two spaces sandwiched between these three diaphragms. SOLUTION: A process pressure to be measured is applied to the surfaces of H- and L-side seal diaphragms 2 and 3 through pressure introducing holes hH and hL formed on both sides of a capsule body 4. If the rigidity of the H-side seal diaphragm 2 is so small that it may be disregarded as compared to that of a center diaphragm 1, the diaphragm 2 bends rightward correspondingly to the rigidity of the center diaphragm 1. When an excessively high pressure is applied from the H-side, the L-side seal diaphragm 3 comes into contact with the backup surface BPL of the capsule body 4 and the displacement of the three diaphragms 1, 2, and 3 is stopped. In addition, the pressure works as the static pressure of a pressure receiving sensor section 5 while the differential pressure caused by the rigidity of the center diaphragm 1 is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure gauge, and more particularly to an improvement of an excessive pressure protection mechanism for preventing an excessively large differential pressure from being applied to a pressure receiving sensor.

[0002]

2. Description of the Related Art In a differential pressure gauge, when the pressure receiving sensor itself cannot protect against excessive differential pressure (semiconductor sensor, etc.).
As shown in FIG. 2, a protection mechanism against excessive pressure is provided in the structure of the capsule itself. The structure shown in FIG. 2 is called a center diaphragm system, in which two spaces A and B divided by a center diaphragm 1 at the center, sealing diaphragms 2 and 3 receiving a measurement pressure, and a capsule facing the sealing diaphragms 2 and 3 are shown. Narrow spaces H, L sandwiched between backup surfaces BPH, BPL of body 4
And four spaces in total. The interior of each of these spaces is filled with oil.

For example, when an excessive pressure is applied only from the H side, the seal diaphragm 2 moves until the seal diaphragm 2 hits the backup surface BPH of the opposing capsule body 4.
A predetermined amount of volume moves to the space A on the H side of the center diaphragm 1 as the seal diaphragm 2 moves. At this time, the center diaphragm 1 expands to the right side, and the oil in the right space B of the center diaphragm 1 moves to the gap L between the seal diaphragm 3 on the L side and the backup surface BPL to expand the seal diaphragm 3. When the one-side excessive pressure is applied in this manner, a pressure difference equal to or greater than a certain value according to the spring constant of the center diaphragm 1 is prevented from being applied to the pressure receiving sensor 5.

[0004]

Such a center diaphragm system is the most typical overpressure protection mechanism in a differential pressure gauge, and has a proven track record. However, the backup spaces H and L for the seal diaphragms 2 and 3 and the moving spaces A and B for the center diaphragm 1 are required separately on the H and L sides, respectively, which complicates the structure. The present invention has been made in view of such a point, and an object of the present invention is to simplify the structure of an overpressure protection mechanism inside a space of a capsule body with respect to a pressure receiving sensor unit.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, a center diaphragm and a center diaphragm are provided inside a space of a capsule body having pressure introduction holes formed on both sides. The seal diaphragm is attached so as to sandwich the pressure sensor, and pressure is introduced to the pressure receiving sensor section from two spaces sandwiched between these three diaphragms.

[0006] According to such a structure, an overpressure on only one side can be transmitted as a static pressure to the pressure receiving sensor section with a simple internal configuration of the space of the capsule body. The invention of claim 2 of the present invention is characterized in that the pressure introducing hole is filled with a porous member to reduce stress concentration. Furthermore, the invention of claim 3 of the present invention is characterized in that a part of the body is made porous to reduce stress concentration.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing an example of an embodiment of the present invention, and portions common to FIG. 2 are denoted by the same reference numerals. In the figure, a center diaphragm 1 and seal diaphragms 2 and 3 are attached so as to sandwich the center diaphragm 1 in a space inside a capsule body 4 having pressure introduction holes hH and hL formed on both sides. These three
Pressure is introduced into the pressure receiving sensor unit 5 from two spaces C and D sandwiched between the diaphragms 1, 2 and 3. A center diaphragm 1 is provided between the seal diaphragms 2 and 3 and the opposing backup surfaces BPH and BPL of the capsule body 4.
A gap is formed in accordance with the rigidity of the pressure sensor and the pressure resistance of the pressure receiving section sensor 5. The calculation of this portion is performed according to the design guideline of the center diaphragm 1.

The operation of such a configuration will be described. The process pressure to be measured is applied to the H-side and L-side seal diaphragms 2 and 3 through pressure introduction holes hH and hL formed on both sides of the body 4. Assuming that a pressure is applied from the H side, if the rigidity of the seal diaphragm 2 is negligibly small compared to the rigidity of the center diaphragm 1, it bends to the right according to the rigidity of the center diaphragm 1. When an excessive pressure is applied from the H side, the L side seal diaphragm 3 comes into contact with the backup surface BPL of the capsule body 4, and the displacement of the three diaphragms stops (ignoring the deformation due to the compression of the oil) and the center. Differential pressure due to the rigidity of diaphragm 1 (pressure receiving sensor 5
Of the pressure receiving section sensor 5 while maintaining the pressure of the pressure receiving section 5 below the excessive pressure.

In the conventional center diaphragm system, the seal diaphragm 1 contacts the backup surfaces BPH, BPL to shut off the process pressure and not transmit the pressure to the pressure receiving sensor 5, but in the present invention, after the contact, The measurement is performed by replacing the pressure with the static pressure while maintaining the differential pressure designed so as not to destroy the pressure receiving portion sensor 5, and the operation of this portion is a great difference between the conventional center diaphragm system and the present invention. . When the seal diaphragm is made thin to reduce the rigidity, the pressure introduction hole h
In the vicinity of H and hL, there is a concern that stress may be concentrated during backup. On the other hand, the pressure introduction holes hH, h
This problem can be solved by filling L with a porous material or making a part of the body 4 porous.

[0010]

As described above, according to the present invention,
The structure of the overpressure protection mechanism inside the space of the capsule body with respect to the pressure receiving sensor can be simply and miniaturized. As a result, the space in which the oil is to be filled can be reduced in principle to half or less of the conventional configuration, and the temperature characteristics can be improved by reducing the sealing liquid. Further, since the whole can be miniaturized, it becomes possible to manufacture a differential pressure sensor unit with built-in overpressure protection. Furthermore, the abnormal state of the one-side overpressure in the conventional configuration is only the determination of the presence or absence of an abnormality. However, according to the present invention, since the one-side overpressure level can be monitored as a static pressure, continuous monitoring at the time of an abnormality becomes possible. .

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of a differential pressure gauge according to the present invention.

FIG. 2 is a configuration diagram of a conventional differential pressure gauge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Center diaphragm 2 H side seal diaphragm 3 L side seal diaphragm 4 Capsule body 5 Pressure sensor

Claims (3)

[Claims] 1. A center diaphragm and a seal diaphragm are mounted so as to sandwich the center diaphragm in a space of a capsule body having pressure introduction holes formed on both sides, and a pressure receiving sensor section is formed from two spaces sandwiched by these three diaphragms. A differential pressure gauge characterized in that pressure is introduced into the pressure gauge. 2. The differential pressure gauge according to claim 1, wherein the pressure introducing hole is filled with a porous member to reduce stress concentration. 3. The differential pressure gauge according to claim 1, wherein a part of the body is made porous to reduce stress concentration.