JPH0628667Y2 - Pressure gauge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a pressure gauge for measuring a slight differential pressure.

[Conventional technology]

Conventionally, a pressure gauge shown in FIG. 5 is known as a pressure gauge used for adjusting the span of an object to be measured such as a differential pressure transmitter for measuring a fluid pressure in an industrial process. This pressure gauge is provided with a measuring device main body 2 having a built-in pressure sensitive sensor 1 made of a silicon diaphragm 1A, an external reference pressure generator 3 such as a cylinder, and one chamber 4 of the pressure sensitive sensor 1 and an object to be measured. One pressure receiving chamber of the differential pressure transmitter 5 and the pressure generator 3 are connected by an air circuit A ₁ , A ₂ , A _3, and the other chamber 6 of the pressure sensor 1 and the differential pressure transmitter 5 are connected. The pressure receiving chamber is connected to the other pressure receiving chamber by an air circuit A ₄ which is open to the atmosphere.
By applying the reference pressure to the pressure sensor 1 and the differential pressure transmitter 5,
The pressure measured by the differential pressure transmitter 5 is compared with the pressure measured by the pressure sensitive sensor 1, and the span of the differential pressure transmitter 5 is adjusted so that the values match.

[Problems to be solved by the device]

However, in such a conventional pressure gauge, since the air circuits A ₁ , A ₂ , and A ₃ form a closed system,
There is a problem that the output of the pressure gauge changes due to the influence of the ambient temperature during measurement. For example, when the pressure generator 3 is operated by pushing it by hand, the internal pressure of the generator 3 and the pressure in the air circuits A ₁ , A ₂ , A ₃ are easily measured in the case of measuring a slight differential pressure because of the influence of body temperature. Will change to. By the way, if there is no volume change and the temperature changes from 10 ℃ to 15 ℃, in the case of a standard pressure of 6mmH ₂ O, ∴P = 6.10mmH ₂ O And an output error of 1.6% occurs.

Actually, the display of the pressure gauge changes momentarily due to the temperature change in the laboratory (the pressure generated by the pressure generator changes due to the temperature change), and the span adjustment of the measured object is changed. This is extremely troublesome when calibrating.

That is, as a method of adjusting the span, the output of the object to be measured is usually displayed by a digital voltmeter and the pressure generator 3
The span adjustment is performed while observing the output of the digital voltmeter while confirming with the pressure gauge that the pressure uttered by the pressure gauge is constant, so if the value of the reference pressure gauge changes, accurate span adjustment can be performed. Because it will disappear.

Therefore, the present invention solves the above-mentioned problems,
An object of the present invention is to provide a pressure gauge capable of effectively absorbing a pressure fluctuation due to a temperature change with a simple structure and easily performing span adjustment and the like.

[Means for Solving the Problems]

In order to achieve the above object, the present invention defines a sensor chamber into two chambers by a pressure-sensitive sensor, one chamber of which is provided with an external reference pressure generator and an object to be measured by a first communication passage. One of the pressure measuring units is connected, and the other chamber is connected to the other pressure measuring unit of the object to be measured by a second communicating passage having an atmosphere opening hole, and these chambers are connected between the first and second communicating passages. A diaphragm chamber communicating with both communication passages is provided, and the inside of the diaphragm chamber is defined into a first chamber communicating with the first communication passage by the diaphragm and a second chamber communicating with the second communication passage, and the compliance of the diaphragm is defined. It is set to be larger than that of the silicon diaphragm of the pressure-sensitive sensor.

[Action]

In the present invention, if the compliance of the diaphragm is made larger than that of the silicon diaphragm, when the reference pressure is applied, the diaphragm is deformed and the silicon diaphragm is also deformed, and then the steady state is achieved.
After that, in the minute volume change due to the temperature change, the silicon diaphragm is not deformed so much due to the difference in compliance, and only the diaphragm is deformed to absorb the volume expansion.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of a pressure gauge according to the present invention, FIG. 2 is a sectional view of an essential part showing a state before a reference pressure is applied, and FIG. 3 shows a state where a reference pressure is applied. FIG. In the figure, the same components and parts as those in FIG. In these figures, the enclosed air circuits A ₁ , A ₂ , A ₃ are
The air circuit A ₄ that constitutes the communication passage 10 and has the atmosphere opening hole 11 constitutes the second communication passage 12, and these both communication passages 10,
A diaphragm chamber 13 is provided between the two chambers 12, and the inside of the diaphragm chamber 13 is divided into two chambers by a diaphragm 14, that is, a first chamber 13A.
And the second room 13B. The first chamber 13A has an air circuit A ₁
And the second chamber 13B communicates with the other chamber 6 of the pressure sensor 1 and the second communication passage 12. The compliance Φ _{1 of the} diaphragm 14 is set larger than the compliance Φ ₂ of the silicon diaphragm 1A of the pressure sensitive sensor 1 (Φ ₁ > Φ ₂ ). Other configurations are similar to the conventional structure.

In the pressure gauge having such a configuration, the pressure generator 3
When the reference pressure P _{0 is applied} to the pressure sensitive sensor 1 and the differential pressure transmitter 5 to be measured, the diaphragm 14 is deformed to the right in FIG. 3 according to the reference pressure. At this time, the silicon diaphragm 1A of the pressure sensitive sensor 1 is also deformed to the right and enters a steady state. When a slight volume change due to a temperature change occurs in such a steady state, since the diaphragm 14 is not provided in the past, this directly acts on the silicon diaphragm 1A to cause an output fluctuation, but in the present invention, the compliance Φ ₁ Since the large diaphragm 14 is deformed by the volume change accompanying temperature change and absorbs the volume expansion, the silicon diaphragm 1A does not change so much, so that the output of the pressure gauge is substantially constant and the differential pressure transmitter 5 The span adjustment can be performed easily and in a short time.

FIG. 4 is a sectional view showing the main part of another embodiment of the present invention.
In this embodiment, a protection mechanism 20 is incorporated to prevent the diaphragm 14 from being damaged by excessive pressure. The protection mechanism 20 is provided with small chambers 21 and 22 immediately in front of the diaphragm chambers 13 of the air circuits A ₁ and A ₄ , respectively, and penetrates through the diaphragm chamber 13 and its center is welded and fixed to the central portion of the diaphragm 14. Both ends are the small chamber 2
1 and 22 are inserted into the respective positions, and circuit closing plates 26 and 27 are provided at both ends thereof to prevent excessive pressure P ₁ (or P
_{When 2} ) acts on the circuit closing plate 26 (or 27), the circuit closing plate 26 (or 27) is brought into close contact with the O-ring 28 (or 29), and the first chamber 13A and the small chamber 21 (or the second chamber).
The communication between the chamber 13B and the small chamber 22) is cut off so that the excessive pressure P ₁ or P ₂ does not act on the diaphragm 14.

[Effect of device]

As described above, according to the pressure gauge of the present invention, the diaphragm chamber is provided, and the diaphragm having the compliance larger than that of the silicon diaphragm of the pressure-sensitive sensor is provided therein to absorb the volume change due to the temperature change. As a result, the deformation of the silicon diaphragm due to temperature changes can be effectively prevented after reaching a steady state, and therefore the measurement pressure is constant regardless of the temperature changes, and the span adjustment work of the measured object can be performed. make it easier.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a pressure gauge according to the present invention, FIG. 2 is a cross-sectional view of a main part showing a state before applying a reference pressure, and FIG. 3 is a state after applying a reference pressure. FIG. 4 is a sectional view showing a protection mechanism of the diaphragm, and FIG. 5 is a schematic configuration diagram of a conventional pressure gauge. 1 ... Pressure-sensitive sensor, 1A ... Silicon diaphragm, 3 ...
… Pressure generator, 4 …… One chamber, 5 …… Differential pressure transmitter, 6
... other chamber, 10 ... first communication passage, 11 ... atmosphere opening hole, 12 ... second communication passage, 13 ... diaphragm chamber, 13
A …… first chamber, 13B …… second chamber, 14 …… diaphragm,
A _{1 to} A ₄ ... Air circuit.

Claims (1)

[Scope of utility model registration request] 1. A sensor chamber is defined by a silicon diaphragm of a pressure-sensitive sensor into two chambers, one chamber of which is measured by a first communication passage to measure pressure of one of an external reference pressure generator and an object to be measured. And the other chamber is connected to the other pressure measuring portion of the object to be measured by a second communication passage having an atmosphere opening hole, and these communication passages are connected between the first and second communication passages. A diaphragm chamber that communicates is provided, and the inside thereof is divided into a first chamber that communicates with the first communication passage by the diaphragm and a second chamber that communicates with the second communication passage, and the compliance of the diaphragm is defined by that of the silicon diaphragm. A pressure gauge characterized by being set larger than that.