JPH1194671A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make measuring operation stable against temperature change of a fluid to be measured, and to enhance the temperature characteristic, by providing a low thermal expansion coefficient body to offset the expansion portion of an sealed liquid by thermal expansion coefficient difference between the body and a pressure receiving body, and by providing an heat insulation part between the pressure receiving part and a sensor. SOLUTION: When fluid A to be measured in contact with a seal diaphragm 4 is changed to have a high temperature (or a low temperature), a pressure sensor element 7 is protected from temperature change load by an insulation function of an insulation part 12 (for example, a radiation fin). Expansion (or shrinkage) of a sealed liquid 3 generated at the temperature change of the fluid A is offset by thermal expansion difference between a pressure receiving body 2 and a low thermal expansion coefficient body 11 comprising a nickel alloy in its inside to prevent generation of a pressure change of the sealed liquid 3. Since the pressure change due to the temperature change of the measured fluid A is not detected thereby, the pressure of the fluid A is accurately measured without requiring any correction caused by the temperature change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor which can operate stably with respect to a temperature change of a measurement fluid and has good temperature characteristics.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of the configuration of a conventional example generally used in the prior art. In FIG. 1, reference numeral 1 denotes a pressure receiving portion in which a sealed liquid 3 is filled in a pressure receiving body 2 and comes into contact with a measurement fluid A via a seal diaphragm 4.

[0005] Reference numeral 5 denotes a conduit having one end connected to the pressure receiving section 1 and through which the sealed liquid 3 flows. Reference numeral 6 denotes a sensor unit for detecting the pressure of the liquid 3. A pressure sensor element 7 is provided in the sensor section 6, and a confidential terminal 8 for taking out a lead of the pressure sensor element 7 is provided.

[0004] In the above configuration, when the measurement fluid A is applied to the pressure receiving section 1, the sealed liquid 3 is inserted through the seal diaphragm 4.
The pressure of the measurement fluid A is applied. This pressure is applied to the pressure sensor element 7 of the sensor unit 6 via the conduit 5, and the pressure of the measurement fluid A is measured.

[0005]

In such a conventional apparatus, it is desired that the pressure receiving section 1 and the sensor section 6 be close to each other in order to reduce the size of the apparatus. However, when approached, if the temperature of the measurement fluid A is high, the temperature of the sensor section 6 also becomes high. Usually, the sensor section 6 is vulnerable to high temperatures.

Therefore, the pressure receiving section 1 and the sensor section 6 are brought close to each other, and a heat insulating section is provided between the pressure receiving section 1 and the sensor section 6. However, in this case, the sensor unit 6 is connected to the pressure receiving unit 1.
Temperature information cannot be obtained, and temperature correction cannot be performed. For this reason, a temperature sensor is provided in the pressure receiving section 1 and the pressure receiving section 1 is provided.
To get temperature information.

However, this results in (1) a high manufacturing cost. (2) Since an extra temperature sensor is provided, the reliability is reduced accordingly.

The present invention solves this problem. An object of the present invention is to provide a pressure sensor that can operate stably with respect to a temperature change of a measurement fluid and has good temperature characteristics.

[0009]

In order to achieve the above object, the present invention provides: (1) a pressure-receiving portion which is filled with a sealed liquid inside a pressure-receiving body and comes into contact with a measurement fluid via a seal diaphragm; A pressure sensor having a sensor section for detecting the pressure of the liquid, wherein a small amount of the sealing liquid is provided in a portion filled with the sealing liquid, and the sealing is performed by a difference in thermal expansion coefficient with the pressure receiving body with respect to a temperature change. A low thermal expansion coefficient object selected so that the expansion of the liquid is offset, and a heat insulating portion provided between the pressure receiving portion and the sensor portion to insulate the sensor portion from the pressure receiving portion. Features pressure sensor. 2. The pressure sensor according to claim 1, further comprising: a pressure receiving body made of stainless steel; and a low thermal expansion coefficient body made of a nickel alloy. (3) The pressure sensor according to (1) or (2), further comprising a heat insulating portion including a radiation fin. It is what constituted.

[0010]

In the above construction, when the measurement fluid is applied to the pressure receiving portion 1, the pressure of the measurement fluid is applied to the sealed liquid via the seal diaphragm. This pressure is applied to the pressure sensor element of the sensor unit via the heat insulating unit, and the pressure of the measurement fluid is measured.

Thus, when the measurement fluid in contact with the seal diaphragm changes to a high temperature (or a low temperature),
Due to the heat insulating function of the heat insulating part, the pressure sensor element is protected from a load caused by a temperature change.

Further, the expansion (shrinkage) of the sealed liquid caused by the temperature change is offset by the difference in the thermal expansion coefficient between the low thermal expansion coefficient body and the pressure receiving body, so that the pressure of the sealed liquid does not change.

Thus, the pressure sensor element does not detect a pressure change due to a temperature change of the measurement fluid, and can accurately measure the pressure of the measurement fluid. In short, by providing the heat insulating part, the pressure sensor part is made temperature-independent from the pressure receiving part.

[0014] The pressure correction by the temperature change of the measurement fluid, which becomes more necessary as the pressure sensor section becomes more independent of the temperature from the pressure receiving section, is made unnecessary by providing the low thermal expansion coefficient body. . Hereinafter, a detailed description will be given based on embodiments.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a main part of an embodiment of the present invention. In the figure, the configuration of the same symbol as FIG. 4 represents the same function. Hereinafter, only differences from FIG. 4 will be described.

Reference numeral 11 denotes a portion provided with a small amount of the filled liquid 3 in a portion filled with the filled liquid 3 inside the pressure receiving body. It is a low thermal expansion coefficient object selected so that the expansion of the liquid 3 is offset. In this case, the pressure receiving body 2 is made of stainless steel, and the low thermal expansion coefficient body is made of a nickel alloy.

Reference numeral 12 denotes a heat insulating section provided between the pressure receiving section 1 and the sensor section 6 to insulate the sensor section 6 from the pressure receiving section 1. In this case, the heat insulating portion 12 is formed of a radiation fin.

In the above configuration, when the measurement fluid A is applied to the pressure receiving section 1, the sealed liquid 3 is inserted through the seal diaphragm 4.
The pressure of the measurement fluid A is applied. This pressure is applied to the insulation 12
Via the pressure sensor element 7 of the sensor section 6, and the pressure of the measurement fluid A is measured.

When the temperature of the measurement fluid A in contact with the seal diaphragm 4 changes to a high temperature (or a low temperature), the pressure sensor element 7 is activated by the heat insulating function of the heat insulating portion 12.
Are protected from the load of temperature changes.

The expansion (shrinkage) of the sealed liquid 3 caused by the temperature change is caused by the low thermal expansion coefficient body 11 and the pressure receiving body 2.
And there is no change in the pressure of the sealed liquid 3.

As a result, the pressure sensor element 7
A pressure change due to a temperature change of the measurement fluid A is not detected,
The pressure of the measurement fluid A can be accurately measured. In short, by providing the heat insulating part 12, the pressure sensor part 6
The pressure receiving unit 1 was made unrelated to temperature.

The more the pressure sensor unit 6 becomes more irrelevant in temperature with respect to the pressure receiving unit 1, the more necessary the measurement fluid A
The pressure correction due to the temperature change of the above is made unnecessary by providing the low thermal expansion coefficient body 11.

As a result, (1) Since the pressure receiving section 1 and the pressure sensor section 6 are thermally isolated, the pressure sensor section 6 can be protected from the thermal load of the measurement fluid A, and the pressure sensor element 7 can be protected. Can always operate stably, so that a pressure sensor that can operate stably with respect to changes in ambient temperature can be obtained.

(2) The pressure correction for the temperature change of the measurement fluid A, which is required as the pressure sensor unit 6 becomes more irrelevant in temperature from the pressure receiving unit 1, is sealed by providing the low thermal expansion coefficient object 11. The expansion and contraction of the liquid 3 were canceled out positively so as to cancel each other.

Therefore, a measurement error due to a change in the temperature of the measurement fluid A can be reduced, and a pressure sensor with improved measurement accuracy can be obtained.

FIG. 2 is an explanatory diagram of a main part configuration of another embodiment of the present invention. Reference numeral 21 denotes a capillary tube connecting the pressure receiving section 1 and the sensor section 6. The capillary tube 21 constitutes the heat insulating part 12 of FIG. 22 is a sensor body.

FIG. 3 is an explanatory diagram of a main part configuration of another embodiment of the present invention. 31 is a differential pressure measuring device. The differential pressure measuring device 31 constitutes the sensor unit 6 of FIG.

[0028]

As described above in detail, according to the first aspect of the present invention, (1) Since the pressure receiving portion and the pressure sensor portion are thermally isolated, the pressure sensor portion is connected to the measuring fluid. Since the pressure sensor element can be protected from a thermal load and can always operate stably, a pressure sensor that can operate stably with respect to a change in ambient temperature can be obtained.

(2) The more the temperature sensor becomes more independent of the temperature of the pressure receiving part, the more the pressure correction for the temperature change of the measurement fluid is performed. Was made to be offset, and was made unnecessary actively.

Therefore, a measurement error due to a change in the temperature of the measurement fluid can be reduced, and a pressure sensor with improved measurement accuracy can be obtained.

Therefore, according to the present invention, it is possible to realize a pressure sensor which can operate stably with respect to a temperature change of the measurement fluid and has good temperature characteristics.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 3 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 4 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure receiving part 2 Pressure receiving body 3 Filling liquid 4 Seal diaphragm 6 Sensor part 7 Pressure sensor element 8 Security terminal 11 Heat insulation part 12 Low thermal expansion coefficient object 21 Capillary tube 22 Sensor part body 31 Differential pressure measuring device A Measurement fluid

Claims (3)

[Claims] 1. A pressure sensor, comprising: a pressure receiving portion that is filled with a sealed liquid inside a pressure receiving body and comes into contact with a measurement fluid via a seal diaphragm; and a sensor portion that detects a pressure of the sealed liquid. A low-thermal-expansion-coefficient body that is provided so as to leave a small amount of the filled liquid in the filled portion and is selected so that the expansion amount of the filled liquid is offset by a difference in thermal expansion coefficient from the pressure-receiving body with respect to a temperature change; A pressure sensor, comprising: a heat insulating portion provided between the pressure receiving portion and the sensor portion to insulate the sensor portion from the pressure receiving portion. 2. The pressure sensor according to claim 1, further comprising a pressure receiving body made of stainless steel and a low thermal expansion coefficient body made of a nickel alloy. 3. The pressure sensor according to claim 1, further comprising a heat insulating portion comprising a radiation fin.