JPS60205331A - Instrument for measuring differential pressure - Google Patents

Abstract

PURPOSE:To provide the titled device for eliminating the effect of thermal expansion stress of a housing on a measuring diaphragm, by fixing a capusle in which a measuring diaphragm is incorporated and a housing on the outside of the capusle with an elastic member of a thin plate. CONSTITUTION:A measuring diaphragm 1 is provided in the middle of a capusle 4, insulating materials 5, 6 are provided on both sides and tubes 7, 8 for a pressurized liquid are provided. Also a housing 13 is provided outside the capusle 4 and sealing diaphragms 16, 17 on both faces. Covers 23, 24 are also provided outside the housing 13. The measurement is performed by detecting with the measuring diaphragm 1 the external pressure which is added on the sealing diaphragms 16, 17 and conveyed further to the pressurized liquid of the tubes 7, 8. In this case, the end of the tube 8 on one side 3 of the capusle 4 and the central part of the housing 13b are fixed via a bellows of an elastic member of a thin plate. Consequently the thermal expansion stress of the housing is absorbed by the elastic member of the thin plate, and the shape of the capusle is stabilized and the pressure is measured with a higher accuracy by the measuring diaphragm.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a differential pressure measuring device. The present invention relates to a differential pressure measuring device of a triple diaphragm type that leads to both sides, and moreover, the differential pressure measuring device has a structure in which a measuring capsule provided with a measuring diaphragm is accommodated in an internal cavity of a housing.

(Prior Art) A triple diaphragm type pressure measuring device having a measuring capsule built into a housing is known.

In this differential pressure measuring device, it is important to prevent external forces applied to the housing and forces caused by temperature changes from being transmitted to the measuring capsule in order to improve measurement accuracy and also to prevent temperature changes. Zero error and temperature span f
The first thing that makes up the difference is the image quality. Therefore, various proposals for improvement regarding this point have been made in the past, but none has provided an effective solution.

(Objective of the Invention) The present invention has been made in view of the above points, and its object is to realize a differential pressure measuring device with a simple configuration, low temperature zero error, small temperature span error, and high measurement accuracy. There is a particular thing.

(Structure of the Invention) The present invention achieves this object in a differential pressure measuring device having a structure in which a measuring capsule consisting of a measuring diaphragm and a body holding the measuring diaphragm is housed in an internal space of a housing. It is characterized in that tube portions are provided on both sides, one tube portion being coupled to the housing, and the other tube portion being coupled to the housing via a thin plate elastic member.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention.

In this device, 1 is a measurement diaphragm formed of a flat plate, 2.3 is a disk-shaped body that holds the measurement diaphragm 1 between them, and the cough bodies 2 and 3 together with the measurement diaphragm 1 constitute a measurement capsule 4. The opposing recesses of the bodies 2 and 3 are filled with an insulating material 5.6 to form a spherical concave surface, and a tube 7.8 is protruded from the center of the side surface. Inside the measuring capsule 4 there are measuring chambers 9 separated by measuring diaphragms 1. ．． 10 is formed,
Furthermore, a capacitor plate is formed in the form of a thin film on the concave surface of the insulating material 5.6. The deflection (displacement) of the measuring diaphragm 1 is determined by the deflection (displacement) of the measuring diaphragm 1 and each capacitor plate 11.
12 is detected as a change in capacitance between the two. Reference numeral 13 denotes a housing in which the measurement capsule 4 is housed, and the internal space 1 is
4 and a disc-shaped lid part 13b, both of which have tubes 7.8 of the body 2.3 in the center.
A through hole is drilled through which the is inserted.

Here, the measuring capsule 4 is accommodated in an internal cavity 14 of the housing body part 13a, one tube 7 is fixed to the housing body part 13a, for example by welding, and the other tube 8 is connected to the housing lid via a solder 15. Part 13b
is fixed to. In addition, the housing body part 138 and the lid part 13
After the measurement capsule 4 is built into the internal cavity of the housing, it is welded and becomes an integral part. Seal diaphragms 16 and 17 receive the two pressures that are the targets of differential pressure measurement, and are welded to the peripheral edges of both side surfaces of the housing 13 while being pressed by annular plates 25 and 26, and are attached to the housing main body 13a. Pressure receiving chambers 18 and 19 are formed on the outer surface of the lid portion 13b, respectively. And this pressure receiving chamber 18
, 19 are communication holes 21 bored in the measurement capsule 4.
．． 22 communicate with measuring chambers 9 and 10, respectively.

These pressure receiving chambers 18 and 19, measurement chambers 9 and 10, and communication hole 2
An incompressible fluid (for example, zircon oil) is sealed in the seal diaphragms 16, 17.
The pressure experienced by is guided to both sides of the measuring diaphragm 10,
This measuring diaphragm 1 is displaced depending on the pressure difference between the measuring chambers 9 and 10.

Reference numerals 23 and 24 denote covers that are disposed opposite to the seal diaphragms 16 and 17 and form a chamber into which the pressure fluid to be measured is introduced, and the bolts 29 and nuts 30 are tightened by force, and are connected to the housing through gaskets 27 and 28. It is pressed against the 13 side (annular plate 25, 26). As a result, each chamber into which the pressure fluid to be measured is introduced has a seal diaphragm 16
, 17, the cover 23.24 and the gasket 27.28.

In this embodiment with such a configuration, the measurement capsule 4 includes one tube 7, the other tube 8, and the bellows 15.
is supported within the internal cavity 14 of the housing 13 via. Therefore, the tensile force or compressive force generated by the difference between the linear expansion coefficient αl of the housing 13 and the linear expansion coefficient α2 of the measuring capsule 4 (usually α1>α2), or the force applied from the outside or the tightening of the bolts 29 and nuts 30 The force is absorbed by the bellows 15 and tube 7.8,
No tension change occurs in the measuring diaphragm 1.

FIG. 2 is a sectional view of essential parts showing another embodiment of the present invention. In this embodiment, a cup 31 is used instead of the bellows,
The tube 8 is passed through the cup 31 to the housing lid part 13b.
It is combined with

Here, Wd indicates a welded portion between the cup 31, the tube portion 8, and the housing lid portion 13b. Even with this configuration, the same effect as the embodiment shown in FIG. 1 can be obtained.

In the above explanation, the displacement corresponding to the pressure difference of the measuring diaphragm 1 is detected as a change in capacitance. The displacement of the measurement diaphragm 1 may also be detected from. Further, the tube portion 8 and the housing lid portion 13b may be connected through a thin plate elastic member such as a diaphragm, instead of a bellows or a saw tab.

<Effects of the Invention> As explained above, according to the present invention, it is possible to reduce the influence of external forces applied to the housing and various forces caused by temperature changes on the measurement diaphragm with a simple configuration. A differential pressure measuring device with small zero error and temperature span error and high measurement accuracy can be realized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a cross-sectional view of essential parts showing another embodiment of the present invention. 1...Measuring diaphragm 2.3...Body 4...Measuring capsule 7.8...
・Tube portion 11.12...Capacitor plate 13...Housing 14...Internal space 15...
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Claims (1)

[Claims] In a differential pressure measuring device configured such that a measuring capsule consisting of a measuring diaphragm and a body holding the measuring diaphragm is housed in an internal space of a housing, tube parts are provided on both sides of the measuring capsule, and one tube part is connected to the measuring capsule. What is claimed is: 1. A differential pressure measuring device, characterized in that it is coupled to a housing, and the other tube section is coupled to the housing via a thin plate elastic member.