JPS6366430A - Differential pressure measuring apparatus - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy, by simplifying an excessive pressure protective mechanism to reduce the amount of a sealing liquid and reducing the variation of a zero point due to temp. caused by the temp. volumetric expansion of the sealing liquid. CONSTITUTION:The chamber 11 provided in a main body 1 is divided into pressure receiving chambers 12, 13 by a center diaphragm (SDP)2. Whereupon, when the measuring pressures P1, P2 of the receiving chambers 12, 13 are within a measuring range, SDP2 does not displace because of the attraction force of the first ring 32 composed of a permanent magnet and the differential pressure of said measuring pressures is detected by a differential pressure detection mechanism 5. When the measuring pressure P1 of the pressure receiving chamber 12 exceeds the measuring range to reach a predetermined value, a plate 33 moves along with the diaphragm 2 and the large flow of a sealing liquid 101 generates to continue until a sealing diaphragm (DP)41 closely contacts with the main body 1 and, thereafter, the pressure of the pressure receiving chamber 12 does not rise and the ring 32 does not move. When the measuring pressure P2 of the pressure receiving chamber 13 exceeds the measuring range to reach the predetermined value, the flow of a sealing liquid 102 generates until DP42 closely contacts with the main body 1 in the same way as mentioned above and, after the close contact of DP42, the pressure of the pressure receiving chamber 13 does not rise.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a differential pressure measuring device.

More specifically, the present invention relates to an improvement in the overpressure protection mechanism of a differential pressure measuring device.

(Prior Art) FIG. 8 is a diagram illustrating the configuration of a conventional example that has been commonly used. An example of this type of differential pressure measuring device is US Pat. No. 3,756,085.

In the figure, 1a is a block-shaped main body, Ila is a main body I
The chamber 2a is provided in the chamber 11a, and the chamber 2a is provided in the chamber 11a.
This is a bellows that divides 1a into two pressure receiving chambers +2a and 13a. 3a is an overpressure protection mechanism, which is provided within the bellows 2a. 31a is a ring-shaped magnet. 32a is a plate made of a magnetic material that blocks the upper surface of the magnet 31a and forms a chamber 33a with the magnet 31a. 34a is plate 3
2a and the free end of the bellows 2a. 3
A spring 5a is arranged between the plate 32a and the bellows 2a. Seal diaphragms 41a and 42a are provided on the outer surface of the main body 1a and constitute seal chambers 43a and 44a. 5a is a differential pressure detection mechanism provided within the main body la, and in this case, a semiconductor pressure detection element is used. 14a and 15a are seal chambers 43
a, 44a are communicating holes with the pressure receiving chambers 12a, 13a. 16a, +7a are communicating holes 14a, +5
This is a connecting hole that connects a and the differential pressure detector m5a. 10
1a is a sealed liquid that fills the pressure receiving chamber 12a, the communication hole 15a, the spinning hole 17a, and the sealing chamber 44a. 102a is a pressure receiving chamber 13a, a communication hole 14a, a connection hole 16a and a seal chamber 43.
This is the filling liquid that fills a.

In the above configuration, if the measured pressures P, P2 are within the measurement range, the differential pressure detection mechanism 5a measures the differential pressure.

When the measured pressure P becomes equal to or higher than a predetermined pressure, the plate 32a is pressed and moves upward in the figure. The bellows 23 extends, the sealed liquid 102 moves, and the seal diaphragm 41
a is backed up by the main body 1a, and the pressure does not rise any further. That is, the overpressure protection mechanism 3a operates in a snap manner.

(Problem to be solved by the invention) However, in such a device, the measurement pressure P2
In response to excessive pressure from 11I, a snap action like that on the P1 side cannot be performed.

The use of two similar devices would allow snapping action in both directions, but would result in a very complex and expensive structure.

The present invention solves this problem.

An object of the present invention is to simplify the overpressure protection mechanism, reduce the number of parts compared to the conventional example, make it cheaper, and reduce the size of the overpressure protection mechanism, thereby reducing the amount of sealed liquid and reducing the temperature of the sealed liquid. It is an object of the present invention to provide a differential pressure measuring device that can improve accuracy by reducing zero point fluctuation due to temperature caused by expansion.

(Means for Solving the Problems) In order to solve this object, the present invention includes a block-shaped main body, a chamber provided in the main body, and a chamber provided in a chamber that is divided into two pressure-receiving chambers. a center diaphragm; a differential pressure detection mechanism that receives measured pressure from the pressure receiving chamber; a seal diaphragm that is provided on the outer surface of the block to receive the measured pressure and forms a seal chamber with the block; A differential pressure measuring device comprising a communication hole that communicates with a pressure receiving chamber, and two sealed liquids filled in the communication hole, the seal chamber, and the pressure receiving chamber, respectively, wherein -D:a is provided with a shaft made of a non-magnetic material and attached to the center diaphragm; a first ring slidably inserted into the shaft;
a plate fixed perpendicularly to the other end of the shaft;
A second ring is arranged concentrically with the plate and fixed to the main body, and one of the second ring, the plate, and the first ring is made of a magnetic material, and the other is made of a magnet. This is a differential pressure measuring device that has a zero signature.

(Function) In the above configuration, when the measurement pressure is within the measurement range width,
The center diaphragm does not displace due to the attraction force of the magnet. Therefore, the differential pressure of the measured pressure is detected by the differential pressure detection mechanism.

When one measurement pressure exceeds the measurement range width and reaches a predetermined value, the adsorption between the plate and the first ring is released, the plate moves together with the center diaphragm, the center diaphragm is displaced, and a large flow of the sealed liquid is caused. It happens. This flow continues until the seal diaphragm comes into close contact with the main body, after which the pressure in the pressure receiving chamber does not increase. In this case, the first ring does not move.

When the other measurement pressure exceeds the measurement range width and reaches a predetermined value, the adsorption between the first ring and the second ring is released, the first ring and the plate move together with the center diaphragm, and the center diaphragm is displaced and flow of the enclosed liquid occurs until the seal diaphragm s M into the body. If the seal diaphragm is tightly attached to the main body and the diameter is M, the pressure in the pressure receiving chamber will not increase.

Examples will be described in detail below.

(Example) FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, 1 is a block-shaped main body.

11 is a chamber provided in the main body 1, and 2 is a center diaphragm provided in the chamber 11 to divide the chamber 11 into two pressure receiving chambers 12 and 13. 21 is a plate provided on the center diaphragm 2. 3 is an overpressure protection mechanism, and the second
As shown in the figure, it is provided within a chamber 11. Reference numeral 31 denotes a shaft made of a non-magnetic material, which is provided perpendicularly to the surface of the center diaphragm 2, has one end attached to the center diaphragm 2, and is made of a non-magnetic material. A first ring 32 is slidably inserted into the shaft 31 and is made of a permanent magnet. A plate 33 is fixed perpendicularly to the other end of the shaft 3 and is made of a magnetic material. A second ring 34 is arranged concentrically with the plate and fixed to the main body 1, and is made of a magnetic material. 41.42
is a seal diaphragm provided on the outer surface of the main body I and forming seal chambers 43 and 44. Reference numerals 45 and 46 designate backup nests provided in the main body l facing the seal diaphragms 41 and 42. Reference numeral 5 denotes a differential pressure detection mechanism, in which a semiconductor pressure detection element is used. 14.
Reference numeral 15 denotes a communication hole that communicates the seal chamber 43.44 with the pressure receiving chamber 12.13. Reference numerals 16 and 17 are connection holes that connect the communication holes 14 and 15 and the differential pressure detection mechanism 5. 61 and 62 are the pressure chambers 6 that cover the main body 1 and the seal diaphragms 41 and 42.
This is a cover that constitutes 3°64. 101 is seal chamber 4
3. A sealed liquid that fills the communication hole 14, the pressure receiving chamber 12, and the connection hole 16. 102 is a sealed liquid that fills the pressure receiving chamber 13, the communication hole 15, the seal chamber 44, and the connection hole 17. Enclosed? ff1
In this case, silicone oil is used for lO+, 102.

In the above configuration, when the measurement pressures P, P, are within the measurement range width, the center diaphragm 2 is not displaced due to the attraction force of the magnet. Therefore, the differential pressure between the measured pressures P and P2 is detected by the differential pressure detection mechanism 5.

When the measured 'If-P+ exceeds the measurement range width and reaches a predetermined value, as shown in FIG. 3, the attraction between the plate 33 and the first ring 32 is released, and the plate 33 moves together with the center diaphragm 2. The center diaphragm 2 is displaced and a large flow of the sealed liquid 101 occurs. This flow continues until the seal diaphragm 41 comes into close contact with the main body 1, after which the pressure in the pressure receiving chamber 12 does not increase. In this case, the first ring 32 does not move.

When the measured BE P 2 exceeds the measurement range width and reaches a predetermined value, as shown in FIG. 33 moves with the center diaphragm 2,
The center diaphragm 2 is displaced and movement of the enclosed liquid 102 occurs until the seal diaphragm 42 comes into close contact with the main body 1. After the seal diaphragm 42 is in close contact with the main body l,
The pressure in the pressure receiving chamber 13 does not increase.

The pressure at which the overpressure protection mechanism 3 operates depends on the material of the first ring 32, the plate 33 adsorbed to the first ring 32, and the second
The above operation of changing the edge of the flute surface of the ring 34 will be described in more detail.

The left side is the center diaphragm, where the differential pressure of the center diaphragm 2 is P, the effective area is A1, the center displacement is X, the spring constant for the displacement X is K, the constant related to the adsorption force of the first ring 32 is B, and Xo is a constant. 2, the first term on the right side is the reaction force of the center diaphragm opposing it, and the second term is the approximated adsorption force of the first ring 32. X=pressure at which mechanism 3 operates.

When formula (1) is expressed in a graph, it becomes as shown in FIG.

Even if the pressure P increases from 0 to point 1 (P=Pa at point 1),
No displacement of the center diaphragm 2 occurs.

The moment the adsorption force is released at point 1, the displacement reaches point 2,
Its diameter moves from point 2 to point 3. The displacement X corresponding to point 3' is the displacement when all the liquid sealed in the seal chamber is absorbed by the center diaphragm 2. In this case,
The center diaphragm 2 is designed to leave a small displacement margin. The pressure does not rise above the pressure corresponding to the displacement x3 (pressure at point P).

Next, considering the case where the pressure is decreasing, move from point 3 → point 2 → point 4, and from the lowest point 4 of the pressure, the line goes from point 4 → 5 without passing through the solid line. That is, the characteristic has hysteresis surrounded by points 1-2-4-5. The pressure corresponding to point 5 is designed to exceed the measured pressure range.

The overpressure protection operation for one measurement pressure has been described above, but the overpressure protection operation for the other measurement pressure is similar.

As a result, by utilizing the permanent magnet attraction force, the overpressure protection mechanism 3 can be simplified. Therefore, compared to the conventional example, the number of parts can be reduced and the cost can be reduced. Further, since the overpressure protection mechanism can be miniaturized and installed near the center axis of the center diaphragm, the internal volume increased by the overpressure protection mechanism 3 can be reduced. Therefore, it is possible to reduce the zero temperature fluctuation caused by the expansion of the temperature body 1M of the sealed liquid, and it is possible to realize a differential pressure measuring device that can be highly accurate.

Note that although the shape of the graph in FIG. 5 changes depending on the volume of the enclosed liquid and how each fi variable is conveyed, the basic operation remains the same.

FIG. 6 is an explanatory diagram of the main part of an embodiment of the pond of the present invention.

In this embodiment, the first ring 32b is made of a magnetic material,
The plate 33b and the second ring 34b are made of permanent magnets, and the plate 33b is attached to the shaft 31 with screws 35.

FIG. 7 is an explanatory diagram of the main part configuration of another embodiment of the present invention.

In this embodiment, a portion 32+ of the first ring 32 is magnetized.

It is convenient for encounters where you want to adjust the magnetic force to a small level.

(Effects of the Invention) As explained above, the present invention has a block-shaped main body,
A chamber provided in the main body, a center diaphragm provided in the chamber to divide the chamber into two pressure receiving chambers, a differential pressure detection mechanism for receiving measured pressure from the pressure receiving chamber, and a differential pressure detection mechanism provided on the outer surface of the block. a seal diaphragm that receives measurement pressure and forms a seal chamber with the block; a communication hole that communicates the seal chamber and the pressure receiving chamber; and a communication hole that is filled with the communication hole, the seal chamber, and the pressure chamber, respectively. A differential pressure measuring device comprising two sealed liquids, a shaft made of a non-magnetic material, provided perpendicularly to the surface of the center diaphragm and having one end attached to the center diaphragm, and a shaft that is slidably inserted into the shaft. a first ring fixed to the other end of the shaft, a plate fixed perpendicularly to the other end of the shaft, and a second ring arranged concentrically with the plate and fixed to the main body; plate and said first
Since the differential pressure measuring device is constructed in which one of the rings is made of a magnetic material and the other is made of a magnet, the overpressure protection mechanism can be simplified by utilizing the attraction force of the permanent magnet. Therefore, compared to the conventional example, the number of parts can be reduced and the L QHA can be miniaturized and installed near the central axis of the center diaphragm, which is particularly useful for small-scale FFI, at low cost. The increased internal volume can be reduced by the overpressure protection mechanism. Therefore, it is possible to reduce the temperature zero fluctuation caused by the temperature volumetric expansion of the sealed liquid, and it is possible to realize a differential pressure measuring device that can be highly accurate.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of one embodiment of the present invention, FIGS. 2 to 5 are explanatory diagrams of the operation of FIG. 1, FIG. 6 is an explanatory diagram of the configuration of another embodiment of the invention, and FIG. 8 is a diagram illustrating the configuration of another embodiment of the present invention, and FIG. 8 is a diagram illustrating the configuration of a conventional example that has been generally used. 1... Main body, 101.102... Enclosed liquid, 11.
... Chamber, 12.13 ... Pressure receiving chamber, 14.15 ... Communication hole, 16゜17 ... Connection hole, 2 ... Center diaphragm, 21 ... Plate, 3 ... Excess pressure Inspection Z■
l, 31...shaft, 32...first ring, 33
...Plate, 34...Second ring, 41.42.
... Seal diaphragm, 43.4.4... Seal chamber, 45.46... Pack-up nest, 5... Differential pressure detection mechanism, 61.62... Cover 163, 64...
Pressure chamber. Figure 1

Claims (1)

[Claims] a block-shaped main body, a chamber provided within the main body, a center diaphragm provided in the chamber that divides the chamber into two pressure receiving chambers, and a differential pressure detection mechanism that receives measured pressure from the pressure receiving chamber; a seal diaphragm provided on the outer surface of the block to receive measurement pressure and form a seal chamber with the block; a communication hole communicating the seal chamber and the pressure receiving chamber;
A differential pressure measuring device comprising the communication hole, the seal chamber, and the pressure receiving chamber each filled with two sealed liquids,
a shaft made of a non-magnetic material, which is provided perpendicularly to the surface of the center diaphragm and has one end attached to the center diaphragm; and a first shaft which is slidably inserted into the shaft.
a ring, a plate fixed perpendicularly to the other end of the shaft, and a second ring arranged concentrically with the plate and fixed to the main body, the second ring, the plate and the A differential pressure measuring device characterized in that one of the first rings is made of a magnetic material and the other is made of a magnet.