JPH09133599A - Method and apparatus for measuring gauge pressure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the manufacture of a pressure measuring apparatus while solving the problem incident to the usage thereof. SOLUTION: An ambient pressure sensor 23a detects the pressure difference P2-P1 between the atmospheric pressure P2 and the pressure P1 of a gas A enclosed in a gas chamber 41 while a main measuring pressure sensor 23b detects the pressure difference P3-P1 between the pressure of an object P3 and the pressure P1 of gas A. An electrical signal is then delivered through an amplifier to a subtractor circuit where the gauge pressure P3-P2 of object is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gauge pressure measuring device for measuring a gauge pressure of an object to be measured such as a fluid and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, there is known a gauge pressure measuring device for measuring the gauge pressure of an object to be measured with reference to atmospheric pressure.

A conventional gauge pressure measuring device has an atmospheric port for introducing the atmosphere and an object port for introducing the object to be measured. The atmosphere introduced from the atmosphere port is taken into the atmosphere chamber inside the apparatus, and the measured object introduced from the measured object port is taken into the measured room inside the apparatus. A diaphragm having a strain gauge is provided at the boundary between the atmosphere chamber and the measurement chamber, and the strain gauge changes when the diaphragm is distorted by the pressure difference between the atmospheric pressure and the pressure of the object to be measured. The change in strain gauge is
For example, when the strain gauge is composed of an electric resistance, it means that the resistivity of the resistance changes. Then, the gauge pressure of the object to be measured is measured by the signal obtained by the change of the strain gauge. This signal is
For example, it is a kind of electric signal, and the gauge pressure measured through an appropriate arithmetic processing circuit, display device, etc. is notified to the user based on this electric signal.

[0004]

However, depending on the environment to be measured, dust or water droplets may adhere to the atmospheric port, making it difficult to take the atmosphere into the atmosphere chamber or dust or water droplets. May enter the atmosphere chamber through the atmosphere port, which may damage or damage the electronic circuit for arithmetic processing connected to the gauge pressure sensor provided in the atmosphere chamber. Therefore, the above problem has been solved by connecting a long introduction pipe to the atmosphere port and introducing the atmosphere from a clean external environment. However,
It was troublesome to pull the introduction pipe from a remote place to the measurement place and connect it to the atmosphere port, and the work was troublesome.

Therefore, an absolute pressure sensor that solves the above problem by using an absolute pressure sensor for measuring the pressure of an object to be measured with respect to a vacuum pressure, that is, an absolute pressure instead of the gauge pressure sensor has been commercialized. It is considerably more expensive than the gauge pressure sensor, and there is a problem in terms of the manufacturing cost of the device.

The present invention has been made by paying attention to such problems existing in the prior art. It is an object of the present invention to provide a gauge pressure measuring device which can solve the above problems without using an absolute pressure sensor.

Another object of the present invention is to provide a method by which such a gauge pressure measuring device can be easily manufactured.

[0008]

According to another aspect of the invention, there is provided a gauge pressure measuring device for measuring a gauge pressure of an object to be measured. And a first detection unit for detecting a pressure difference between the pressure of the gas sealed in the sealed chamber and the atmospheric pressure around the apparatus, and performing an output according to the pressure difference, and the sealed unit is sealed in the sealed chamber. A second detection unit that detects a pressure difference between the pressure of the gas and the pressure of the object to be measured and outputs the pressure according to the pressure difference.

According to a second aspect of the present invention, in the gauge pressure measuring device according to the first aspect, the differential pressure detected by the first detection unit and the differential pressure detected by the second detection unit are set. Equipped with a calculation unit that subtracts the gauge pressure of the measured object,
The output is performed according to the gauge pressure obtained by the arithmetic unit.

According to the third aspect of the present invention, a closed chamber in which a gas is sealed from the outside is stored, and a differential pressure between the pressure of the gas sealed in the closed chamber and the atmospheric pressure around the apparatus is detected. , A first detection unit that outputs according to the differential pressure, and a differential pressure between the pressure of the gas sealed in the sealed chamber and the pressure of the object to be measured, and output according to the differential pressure. In a method of manufacturing a gauge pressure measuring device for measuring a gauge pressure of an object to be measured, the main body case is composed of a plurality of case constituent materials, and some of the case constituent materials are 1
In addition to fixing the detection unit of the above, the second detection unit is fixed to the same case constituent material or another case constituent material, and the plurality of case constituent materials are assembled to form a closed chamber in the main body case. is there.

Therefore, the invention according to claims 1 to 3 has the following effects. In the invention according to claim 1, a differential pressure between the pressure of the gas sealed in the sealed chamber and the atmospheric pressure around the device is detected by the first detection unit, and an output according to the differential pressure is performed, The second detector detects the pressure difference between the pressure of the gas sealed in the sealed chamber and the pressure of the object to be measured, and outputs the pressure difference. The pressure difference between the pressure of the gas sealed in the sealed chamber and the atmospheric pressure around the device,
The gauge pressure obtained based on the pressure difference between the pressure of the gas sealed in the sealed chamber and the pressure of the DUT is not affected by the pressure fluctuations in the sealed chamber due to changes in ambient temperature, etc. The pressure can be accurately grasped.

According to the second aspect of the present invention, the differential pressure between the pressure of the gas sealed in the sealed chamber by the computing unit and the atmospheric pressure around the apparatus, the pressure of the gas sealed in the sealed chamber, and the object to be measured. And the differential pressure with the pressure of. An accurate gauge pressure of the object to be measured can be immediately grasped by the output according to the gauge pressure of the object to be measured obtained by the calculation.

According to the third aspect of the invention, since the closed chamber is constructed by assembling a plurality of case constituent materials, it is not necessary to form a vacuum pressure as in the absolute pressure sensor, and the manufacturing is facilitated. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a gauge pressure measuring device according to the present invention will be described below with reference to FIGS. 1 and 2.

As shown in FIG. 1, a gauge pressure measuring device 11
The main body case 12 includes two lower main bodies 13a and 13b,
It is composed of a middle body 14 and an upper body 15. The lower main bodies 13a and 13b, the middle main body 14 and the upper main body 15 respectively constitute the case constituent material of the present invention.

The lower body 13a is provided with an atmospheric port 16 for introducing the atmosphere, and a sensor case 17
A support portion 18a that supports a is provided. Support part 1
A diaphragm 21a is provided below the sensor case 17a supported by the diaphragm 8a.
The atmospheric pressure P2 of the atmosphere introduced from the atmosphere port 16 acts on the lower surface of the. The first electronic circuit board 24a is arranged on the sensor case 17a, and the first electronic circuit board 24a has a surrounding pressure measuring sensor 23 which is a gauge pressure sensor.
a is fixed in a state of being electrically connected. The ambient pressure measuring sensor 23a constitutes the first detection unit of the present invention. An insulating member 22a made of silicon oil is interposed between the diaphragm 21a and the ambient pressure measuring sensor 23a and transmits the atmospheric pressure P2 acting on the diaphragm 21a to the ambient pressure measuring sensor 23a. In addition, the second electronic circuit board 24a above the second electronic circuit board 24a.
The electronic circuit board 25a is supported by the sensor case 17a.

The lower body 13b is provided with an object port 26 for introducing an object to be measured, and a support portion 18b for supporting the sensor case 17b. A diaphragm 21b, on which the pressure P3 of the object to be measured from the object to be measured 26 is applied, is provided below the sensor case 17b supported by the support portion 18b. The first electronic circuit board 24b is arranged on the sensor case 17b, and the main measurement pressure sensor 23b, which is a gauge pressure sensor, is electrically connected to the first electronic circuit board 24b. The main measurement pressure sensor 23b constitutes the second detection unit of the present invention. An insulating member 22b made of silicon oil is interposed between the diaphragm 21b and the main measurement pressure sensor 23b, and the pressure P3 of the object to be measured which acts on the diaphragm 21b.
Is transmitted to the main measurement pressure sensor 23b. In addition, the second electronic circuit board 25b is supported by the sensor case 17b above the first electronic circuit board 24b.

The middle portion main body 14 is provided with a hollow hole 31 having an upper opening, and two sensor case holes 32a and 32b are provided in the lower portion. The sensor cases 17a and 17b have sensor case holes 32a and 32b.
Is inserted into the first and second lower main bodies 13a,
13b is fixed to the middle body 14 with bolts 33. A support portion 34 is provided on the inner circumference of the middle body 14, and a third electronic circuit board 35 is provided on the support portion 34.
Is supported. The first electronic circuit boards 24a, 24
b is electrically connected to the second electronic circuit boards 25a and 25b by lead wires 36a and 36b, respectively, and the second electronic circuit boards 25a and 25b are connected to the third electronic circuit board 35 with lead wires 37a and 37b. Are electrically connected by.

The upper body 15 in which the connector 38 is disposed is fixed to the middle body 14 by bolts 39, and the lead wire 40 connected to the connector 38 is electrically connected to the third electronic circuit board 35. Has been done.

In the gauge pressure measuring device 11 constructed as described above, the upper chamber 15, the middle chamber 14, the two lower chambers 13a and 13b, and the gas chamber 41 as a hermetically sealed chamber are sealed by the sensor cases 17a and 17b. Is formed, and any gas A enclosed in the gas chamber 41 is completely isolated from the external environment. In this embodiment, the gas (atmospheric pressure air) A that is inevitably sealed in the main body case 12 when the upper main body 15, the middle main body 14, and the lower main bodies 13a and 13b are assembled is sealed. In addition, by the upper body 15, the middle body 14, and the lower bodies 13a and 13b,
The case constituent material of the present invention is constituted.

Therefore, the ambient pressure measuring sensor 23a detects the differential pressure P2-P1 between the atmospheric pressure P1 of the sealed gas A and the atmospheric pressure P2 transmitted through the insulating member 22a, and the main measuring pressure sensor 23b is The pressure difference P3-P1 between the pressure P1 of the sealed gas A and the pressure P3 of the measured object transmitted through the insulating member 22b is detected.

Next, the electrical configuration of the gauge pressure measuring device 11 constructed as described above will be described with reference to FIG.
First, the electrical configuration on the ambient pressure measuring sensor 23a side will be described. The constant current circuit D1 is connected to the detection circuit D2 and supplies a constant current to the detection circuit D2. Detection circuit D
2 includes a Wheatstone bridge circuit D2-1 and a variable resistor D2-2, and the Wheatstone bridge circuit D2-1
Is supplied with a constant current from the constant current circuit D1, and the Wheatstone bridge circuit D2-1 is a closed gas A.
The voltage V1 corresponding to the pressure difference between the pressure P1 and the atmospheric pressure P2 is output. The variable resistor D2-2 is used for zero-point adjustment for adjusting the voltage V1 to zero when the pressure difference between the pressure P1 of the sealed gas A and the atmospheric pressure P2 is zero.

An amplifier circuit D3 is connected to the detection circuit D2 and outputs a voltage V2 obtained by amplifying the voltage V1 output from the detection circuit D2. The amplifier circuit D3 is a variable resistor D3.
-1. This variable resistor D3-1 has an amplification factor (V
2 / V1) is used for adjusting the amplification factor.

The electrical structure of the main measurement pressure sensor 23b is the same as that of the ambient pressure measurement sensor 23a. Therefore,
In FIG. 2, the constant current circuit D1, the detection circuit D2, the Wheatstone bridge circuit D2-1, the variable resistor D2-2,
The configuration corresponding to the amplifier circuit D3 and the variable resistor D3-1 is
Detailed description of the constant current circuit d1, the detection circuit d2, the Wheatstone bridge circuit d2-1, the variable resistor d2-2, the amplifier circuit d3, and the variable resistor d3-1 will be omitted. On the side of the main pressure measuring sensor 23b, a voltage V3 corresponding to the differential pressure between the pressure P1 of the gas A and the pressure P3 of the object to be measured is output from the detection circuit d2, and the voltage V4 obtained by amplifying the voltage V3 is output from the amplification circuit d3. Is output.

The amplifier circuit D3 and the amplifier circuit d3 are respectively connected to a subtraction circuit D4 as an arithmetic unit, and subtract the voltage V2 output from the amplifier circuit D3 from the voltage V4 output from the amplifier circuit d3 and output it.

Next, the operation of the gauge pressure measuring device 11 configured as described above will be described. Diaphragm 21
a is the differential pressure P2-P1 between the atmospheric pressure P1 of the gas A and the atmospheric pressure P2.
The diaphragm 21a is distorted due to the action of. When the diaphragm 21a is distorted, the differential force P2-P
1 is transmitted to the ambient pressure measuring sensor 23a via the insulating member 22a filled with silicone oil. Then, stress is applied to the piezoresistor that constitutes the ambient pressure measurement sensor 23a, so that the resistivity of the resistance of the detection circuit D2 changes. When the potential difference V1 is generated due to the change in the resistivity, the potential difference V1 is applied to the input terminal of the amplifier circuit D3. Then, the applied potential difference V1 is amplified to the voltage V2 through the amplifier circuit D3 and then applied to the subtraction circuit D4.

On the other hand, when the atmospheric pressure P1 of the gas A and the pressure P3 of the object to be measured act on the diaphragm 21b, the differential pressure P thereof is generated.
The diaphragm 21b is distorted by the addition of 3-P1. Due to the distortion of the diaphragm 21b, the differential pressure P3-P1 is transmitted to the main measurement pressure sensor 23b through the insulating member 22b. Then, the resistivity of the piezoresistor of the detection circuit d2 constituting the main measurement pressure sensor 23b changes. Then, the potential difference V3 due to the change in resistivity is applied to the input terminal of the amplifier circuit d3. Then, the applied potential difference V3 is amplified to the voltage V4 via the amplifier circuit d3 and then applied to the subtraction circuit D4.

When the voltages V2 and V4 are applied to the subtraction circuit D4, the potential V5 based on the potential difference V4-V2 is output from the output end. Then, the gauge pressures P3-P2 of the object to be measured are obtained as the electric signal B based on the potential V5. Then, the electric signal B is displayed via a connector 38 on a display unit (not shown) provided outside the gauge pressure measuring device 11.

The voltage V2 can be expressed as V2 (P1, P2) with the atmospheric pressure P1 of the gas A and the atmospheric pressure P2 as parameters, while the voltage V4 has V4 (with the atmospheric pressure P1 and the pressure P3 of the object to be measured as parameters. P1, P3). Therefore,
The voltage V4 (P1, P1 applied to the input terminal of the subtraction circuit D4
3) -V2 (P1, P2) does not depend on the parameter P1.

This embodiment has the following advantages. (B) Potential difference V applied to the input terminal of the subtraction circuit D4
Since 4-V2 does not depend on the atmospheric pressure P1, it is possible to measure the gauge pressure P3-P2 of the measured object regardless of the gas A sealed in the gas chamber 41.

(B) Since the gauge sensor is used, the manufacturing cost can be reduced as compared with the case where the absolute pressure sensor is used. (C) Since the gas chamber 41 is hermetically closed, dust, water droplets, etc. do not enter the gas chamber 41 from the outside, and the electronic circuit boards 24a, 24b, 2 arranged in the gas chamber 41 are prevented.
It is possible to prevent the possibility that 5a, 25b, 35 will be broken or damaged due to their influence.

(D) The ambient pressure measuring sensor 23a and the main measuring pressure sensor 23b form a Wheatstone bridge by adjusting the variable resistors D2-2 and d2-2. Therefore, since it is possible to accurately deal with a minute change in the resistivity of the resistance, it is possible to detect the differential pressures P2-P1 and P3-P1 with high accuracy, and the gauge pressure P3- of the object to be measured. It is possible to measure P2 with high accuracy.

The present invention can be embodied with the following modifications. (1) An indicator (meter or A
/ Numerical display after D conversion) is installed, and at least a part of the case is made of a transparent material so that the display can be visually recognized. As a result, the measurement result can be directly displayed.

(2) A signal obtained from the ambient pressure measuring sensor 23a or the main measuring pressure sensor 23b, that is, the potential difference V
1 or V3 is output to an arithmetic circuit provided outside the gauge pressure measuring device via the connector 38 to obtain the gauge pressure P3-P2 of the object to be measured. Also by this, the same effects as the advantages described in (i) to (iv) can be obtained.

(3) The differential pressure P2-P1 measured by the ambient pressure measuring sensor 23a and the differential pressure P3-P1 measured by the main measuring pressure sensor 23b are provided without providing an arithmetic circuit for measuring the gauge pressure. To be displayed individually on the display. This also allows the measurer to individually detect the differential pressure P2-
It becomes possible to know P1, P3-P1 and to know the gauge pressure P3-P2 of the object to be measured.

(4) There is a limit to the withstand voltage value of the pressure sensors 23a and 23b, and if it exceeds the limit, it may cause a failure or the like. Therefore, when either one of the differential pressure P2-P1 measured by the ambient pressure measurement sensor 23a or the differential pressure P3-P1 measured by the main measurement pressure sensor 23b becomes equal to or more than a predetermined value, that effect is notified. Notify the measurer by display or voice. As a result, it is possible to further suppress the possibility of failure or the like due to the pressure resistance of the pressure sensors 23a and 23b.

(5) An introduction stop valve for stopping the introduction of the atmosphere or the object to be measured is provided at the port 16 for the atmosphere or the port 26 for the object to be measured. The differential pressure P2-P1 measured by the ambient pressure measurement sensor 23a or the differential pressure P3-P measured by the main measurement pressure sensor 23b.
When 1 exceeds a specified value, the atmospheric port 16
Alternatively, close the introduction stop valve provided at the port 26 for the object to be measured. Thereby, the pressure sensors 23a, 23b
It is possible to avoid a failure or the like based on the pressure resistance of the.

(6) A plurality of gauge pressure sensors for measuring the differential pressures P2-P1 including the ambient pressure measuring sensor 23a are provided.
Alternatively, a plurality of gauge pressure sensors for measuring the differential pressure P3-P1 including the main measurement pressure sensor 23b are provided, and a circuit for taking an average value of the plurality of sensors is provided. As a result, the differential pressure P
It becomes possible to measure 2-P1 or P3-P1 with higher accuracy.

The technical idea that can be understood from the above embodiment will be described below. (A) When the differential pressure between the pressure of the gas acting on the first detection unit and the atmospheric pressure becomes a predetermined value or more, or the pressure of the gas acting on the second detection unit and the pressure of the person to be measured. The gauge pressure measuring device according to claim 1 or 2, further comprising a notifying means for notifying a measurer of the fact that the differential pressure of 1 is equal to or more than a predetermined value. As a result, it is possible to suppress the possibility of failure of the detection unit.

[0040]

As described in detail above, according to the present invention, the following excellent effects can be obtained. According to the invention of claim 1, since the gas to be measured for the differential pressure between the atmosphere and the object to be measured is stored in a sealed chamber in a sealed state,
It is not affected by the external environment, and the gauge pressure of the measured object can be accurately measured regardless of the type of gas in the closed chamber.

According to the invention described in claim 2, it is possible to easily know the gauge pressure of the object to be measured. According to the invention described in claim 3, it is possible to configure a closed chamber for sealing the gas that is the target of the differential pressure measurement, and avoid the influence of the external environment during the differential pressure measurement. You can

[Brief description of the drawings]

FIG. 1 is a sectional view of a gauge pressure measuring device according to an embodiment.

FIG. 2 is an explanatory diagram illustrating a circuit configuration for performing arithmetic processing.

[Explanation of symbols]

Reference numeral 11 ... Gauge pressure measuring device, 13a, 13b ... Lower body as case constituent material, 14 ... Middle body as case constituent material, 15 ... Upper body as case constituent material, 23a ...
Ambient pressure measuring sensor as a first detection unit, 23b ... Second
, A main measurement pressure sensor as a detection unit of 41, a gas chamber as a closed chamber, P1 ... Atmospheric pressure, P2 ... Atmospheric pressure, P3 ... Pressure of an object to be measured, D2 ... D4, a detection circuit that constitutes the main measurement pressure sensor
... A subtraction circuit as an arithmetic unit.

Claims (3)

[Claims] 1. A gauge pressure measuring device for measuring a gauge pressure of an object to be measured, comprising: a closed chamber containing a gas sealed from the outside; a pressure of the gas sealed in the closed chamber and an atmospheric pressure around the device. The first to detect the differential pressure between the
Second detection unit for detecting the differential pressure between the pressure of the gas sealed in the sealed chamber and the pressure of the object to be measured, and performing an output according to the differential pressure.
Gauge pressure measuring device equipped with a detector. 2. The differential pressure detected by the first detector,
The calculation unit for calculating the gauge pressure of the object to be measured by subtracting the differential pressure detected by the second detection unit, and outputting according to the gauge pressure calculated by the calculation unit. Gauge pressure measuring device described in. 3. A gauge pressure measuring device for measuring a gauge pressure of an object to be measured, comprising: a closed chamber containing a gas sealed from the outside; a pressure of the gas sealed in the closed chamber and an atmospheric pressure around the device. The first to detect the differential pressure between the
Second detection unit for detecting the differential pressure between the pressure of the gas sealed in the sealed chamber and the pressure of the object to be measured, and performing an output according to the differential pressure.
A method for manufacturing a gauge pressure measuring device having a detector part, wherein the main body case is composed of a plurality of case components, and the first detector part is fixed to some of the case components. A method of manufacturing a gauge pressure measuring device, wherein a second chamber is fixed to a case constituent material or another case constituent material, and a sealed chamber is formed in a main body case by assembling the plurality of case constituent materials.