JPH10206264A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the occurrence or the like of shear in zero point correction when gel for transmitting measuring pressure to a sensor tip is used while the pressure can be measured even with measuring fluid eroding the sensor tip, and facilitate the self-diagnosis of the sensor tip. SOLUTION: This sensor is constituted such that measuring fluid pressure influences a built-in sensor tip 1 from a pressure introducing port 2 formed in a casing 5 for pressure detection. Then, the sensor tip 1 makes contact with the inside of a pressure introducing port 2 to fill tip protecting fluid therein and an external pressure transmitting member 6 for sealing the tip protecting fluid 3 outside the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting a measurement fluid pressure to a built-in sensor chip from a pressure inlet formed in a casing and converting a resistance change caused by the pressure applied to the sensor chip into an electric signal. Pressure sensor that measures the pressure of the fluid, specifically, it can measure the pressure even with a measurement fluid of a material that attacks the sensor chip,
In this case, the present invention relates to a technique for avoiding the problem of using a gel-like material that transmits a measured pressure to a sensor chip, and for easily performing self-diagnosis of the sensor chip. .

[0002]

2. Description of the Related Art Conventionally, a measurement fluid pressure is applied to a built-in sensor chip 1 from a pressure inlet 2 formed in a casing, and a resistance change caused by the pressure applied to the sensor chip 1 is converted into an electric signal. As shown in FIG. 5, the pressure sensor for measuring the pressure of the fluid causes the measurement fluid to directly touch the sensor chip 1, so that the pressure sensor must be used for a measurement fluid of a material that attacks the silicon resin-based sensor chip 1. Is something that cannot be done.

[0003] Therefore, as shown in FIG.
Of the sensor chip 1 through the gel-like body 4 by filling the gel-like body 4 with the gel-like body 4 in substantially the entire area thereof.
A pressure sensor has been proposed in which a measurement pressure is applied to the pressure sensor to measure the pressure. However, in the configuration in which the pressure fluid spreads to the sensor chip 1 via the gel-like body 4 as described above, the stress due to the contraction when the liquid hardens to the gel state affects the sensor chip 1 and the offset ( Zero correction), and the shrinkage of the gel-like body 4 due to the temperature change affects the sensor chip 1.
There has been a problem that the offset is shifted and the work environment is susceptible to temperature change.

Further, in the above-described conventional configuration, it is impossible to perform a self-diagnosis as to whether or not the sensor chip 1 is damaged.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem. In the case where the pressure can be measured even with a measuring fluid made of a material which can damage the sensor chip, the present invention is not limited to this. Another object of the present invention is to provide a pressure sensor that can avoid the above-described problem when using a gel-like material that transmits a measured pressure to a sensor chip and that can perform self-diagnosis of the sensor chip.

[0006]

According to the first aspect of the present invention, there is provided a pressure sensor for detecting a pressure by applying a measurement fluid pressure to a built-in sensor chip 1 from a pressure inlet 2 formed in a casing 5. Then, the inside of the pressure inlet 2 is brought into contact with the sensor chip 1 to be filled with the chip protection fluid 3, and the outside of the chip protection fluid 3 is filled with the external pressure transmitting member 6 for sealing the chip protection fluid 3. It is characterized by becoming.

According to a second aspect of the present invention, the tip protection fluid 3 is a fluorine-based oil, and the external pressure transmitting member 6 is a gel-like body 4. Claim 3
The present invention is characterized in that the chip protection fluid 3 is a magnetic fluid 7. The invention according to claim 4 is characterized in that the external pressure transmitting member 6 is a ring-shaped permanent magnet 8, and the magnetic fluid 7 is held inside the ring-shaped permanent magnet 8.

In the configuration of the first aspect, the measurement fluid does not directly touch the sensor chip 1, and the external pressure transmitting member 6 can measure the pressure even if it is a pressure fluid that erodes the sensor chip 1. Sensor chip 1 at the back
The chip protection fluid 3 is sealed at the part touching
The pressure transmission can prevent the tip protection fluid 3 from leaking. For example, when only the gel body 4 is used,
It is possible to prevent the contraction of the gel-like body 4 due to the temperature change from affecting the sensor chip 1, to prevent the offset from being deviated, and to prevent the temperature change of the working environment from greatly affecting the sensor chip 1. Pressure measurements can be made.

According to the structure of the second aspect, in addition to the function of the first aspect, the fluorine-based oil of the chip protection fluid 3 is inactive, so that the corrosion of the sensor chip 1 can be suppressed. Good electrical insulation can be achieved between them, and the fluorine-based oil has a higher specific gravity than the gel-like body 4, so that the two do not mix, and the expected function can be exhibited for a long period of time.

According to the configuration of claim 3, in addition to the function of claim 1 or claim 2, it becomes possible to confirm the breakage of the sensor chip 1 by an external magnetic field, and the self-diagnosis of the sensor chip 1 can be performed. In the configuration of the fourth aspect, in addition to the operation of the first or third aspect, since the external pressure transmitting member 6 is a ring-shaped permanent magnet 8 as compared with the case where the external pressure transmitting member 6 is a gel body 4, the external pressure transmitting member 6 becomes easy to assemble.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. Reference numeral 10 denotes a base, which is formed of an insulating resin into a substantially square bottomed cylinder having an open end 29, and a housing space is provided therein. Reference numeral 12 denotes a glass pedestal, which is formed in a substantially square cylindrical shape by glass such as Pyrex glass and has a shaft hole 13, and one surface orthogonal to the axis of the shaft hole 13 is metallized with a metal by vapor deposition or a scatterer or the like. ing.

Reference numeral 15 denotes a pressure introducing pipe, which is Kovar or FeN.
A pressure introducing hole 16 formed cylindrically by a metal such as an i-alloy and introducing a fluid to be measured with pressure is provided, and one orthogonal surface perpendicular to the axis of the pressure introducing hole 16 is: The axis of the pressure introducing hole 16 and the axis of the shaft hole 13 are aligned with each other, and are joined to one surface of the glass pedestal 12 with solder.

Reference numeral 1 denotes a sensor chip. A strain gauge is formed by arranging a piezoresistor (not shown) on a silicon diaphragm 21 formed in a substantially central portion by a silicon semiconductor. Is bonded to the other surface of the glass pedestal 12 by anodic bonding applying a high DC voltage so as to be positioned on the silicon diaphragm 21 and converts the pressure of the fluid into an electric signal. Such a sensor chip 1 has a known configuration.

As shown in FIG. 1, a casing 5 is formed of a metal such as stainless steel into a tubular shape, and has an insertion hole 23 at a center position. A recess 24 having a concentric step is formed to form a hexagonal bolt, and the pressure introducing tube 15 is inserted into the insertion hole 2.
The base 10 is housed in the recess 24 by being inserted and held in the recess 3. 9 is an O-ring.

The terminal 25 is fixed to the base 10 and has an internal terminal 26 disposed in the accommodation space of the base 10 and an external terminal 27 disposed outside and bent. It is electrically connected to an electrode (not shown) provided on the sensor chip 1 by wire bonding. The printed circuit board 28 is fixed to the concave portion 24 of the casing 5 by a ceramic substrate on which a circuit is formed, and is electrically connected to the sensor chip 1 by inserting and soldering the external terminals 27. Terminal block 30
Is formed by simultaneously molding the connector terminal 30a, and the connector terminal 30a is
5 is continued.

The connector 31 is made of a synthetic resin and has a rectangular tubular attaching / detaching portion 31a and a cylindrical pedestal portion 31b having a diameter larger than the outer shape of the attaching / detaching portion 31a. 5, the connector terminal 30a of the terminal block 30 is
It protrudes into the cylinder 1a and is led out. The operation of the pressure sensor thus configured will be described. With the axes of the pressure introduction hole 16 of the pressure introduction tube 15 and the shaft hole 13 of the glass pedestal 12 aligned with each other, one surface 14 of the glass pedestal 12 is
The pressure introduction hole 16 and the shaft hole 13 communicate with each other since the one surface orthogonal to the one is soldered with solder. In this state, the fluid to be measured for gas or liquid pressure is introduced into the pressure introduction hole 16 of the pressure introduction pipe 15 with a high pressure.

At this time, the sensor chip 1 is hermetically bonded to the glass pedestal 12 by anodic bonding so as to shield the shaft hole 13 of the glass pedestal 12, and the pressure introducing tube 15 is soldered to the glass pedestal 12. . Therefore, the fluid applies the pressure to the sensor chip 1 without leaking to the outside through the outer peripheral portion of the pressure introducing pipe 15. When the pressure of the fluid is applied to the sensor chip 1, the silicon diaphragm 21 formed on the sensor chip 1 bends in proportion to the difference between the pressure of the fluid and the atmospheric pressure. Then, the resistance value of the piezoresistor formed on the silicon diaphragm 21 changes in proportion to the magnitude of the deflection, and outputs this resistance value to the terminal 25 as an electric signal. (Not shown) to amplify the connector terminal 30a.
To measure the fluid pressure.

Here, in the first embodiment, as shown in FIG. 1, the inside of the pressure inlet 2 of the casing 5 and the vicinity of the inside of the pressure introducing pipe 15 are brought into contact with the sensor chip 1. The tip protection fluid 3 (dotted in the figure) is filled. The outside of the chip protection fluid 3 is filled with an external pressure transmitting member 6 (shown by oblique lines in the figure) to seal the chip protection fluid 3. The tip protection fluid 3 is a fluorine-based oil, and the external pressure transmitting member 6 is a gel body (gel) 4. Fluorinated oil is
FOMBLIN (trademark) Y0 manufactured by Ausimont Co., Ltd.
4, but may be other. FOMBLIN (trademark) Y04 manufactured by Ausimont Co., Ltd.
Have the following representative characteristic values.

Average molecular weight 1.500 a. m. u (Measurement method: MAN ZP29 / 24) Kinematic viscosity (20 ° C) 38 cSt (Measurement method: ASTM D445) Kinematic viscosity (40 ° C) 15 cSt (Measurement method: ASTM D445) Kinematic viscosity (100 ° C) 3.2 cSt (Measurement method : ASTM D445) Viscosity index 50 (Measurement method: ASTM D2270) Pour point -58 ° C (Measurement method: ASTM D97) Weight loss (120 ° C) 20% (Measurement method: ASTM D972) Weight loss (149 ° C)-(Measurement) Method: ASTM D972) Weight loss (204 ° C)-(Measurement method: ASTM D972) Density (20 ° C) 1.87 g / cm ² (Measurement method: ASTM D891) Surface tension (20 ° C) 21 dyne / cm (Measurement method: (ASTM D1331) Refractive index 1.294 (Measurement method: MAN PF29 / 3) In the first embodiment, the inside of the pressure inlet 2 is brought into contact with the sensor chip 1 to be filled with the chip protection fluid 3, and the chip protection fluid 3 is sealed outside the chip protection fluid 3. Since the external pressure transmitting member 6 is filled, the measurement fluid does not directly touch the sensor chip 1, and pressure measurement can be performed even with a pressure fluid that erodes the sensor chip 1. Furthermore, when only the gel-like material 4 is used, the contraction of the gel-like material 4 due to the temperature change affects the sensor chip 1, the offset is shifted, and the temperature change of the working environment is large on the sensor chip 1. Influence can be avoided and good pressure measurement can be performed.

In the second embodiment, the tip protection fluid 3 is the above-mentioned fluorine-based oil, the external pressure transmitting member 6 is the gel-like body 4, the fluorine-based oil is inactive, and the sensor chip 1 Corrosion can be suppressed, good electrical insulation can be achieved with the sensor chip 1, the specific gravity of the fluorine-based oil is higher than that of the gel-like body 4, and both are not mixed, and The function can be performed over a long period of time.

In the third embodiment, as shown in FIG. 4, the chip protection fluid 3 is a magnetic fluid 7, and by applying an external magnetic field to the magnetic fluid 7, the sensor chip 1 can be used. Can be confirmed, and the self-diagnosis of the sensor chip 1 can be performed.
In the embodiment of claim 4, as shown in FIG.
The tip protection fluid 3 is a magnetic fluid 7 and the external pressure transmitting member 6 is a ring-shaped permanent magnet 8. The magnetic fluid 7 is held by the ring-shaped permanent magnet 8.
As compared with the case where the external pressure transmitting member 6 is formed into the gel body 4,
Since it is a ring-shaped permanent magnet 8, it can be easily assembled.

[0022]

According to the first aspect of the present invention, there is provided a pressure sensor for detecting a pressure by applying a measured fluid pressure to a built-in sensor chip from a pressure inlet formed in a casing. The sensor fluid is filled inside by contacting the sensor chip, and the external pressure transmitting member that seals the chip protection fluid is filled outside the chip protection fluid. Without, even if the pressure fluid that penetrates the sensor chip, pressure measurement can be performed, the part that touches the sensor chip at the back of the external pressure transmission member is filled with chip protection fluid and sealed, The pressure transmission can prevent the chip protection fluid from leaking.For example, when using only the gel material, the contraction of the gel material due to a temperature change causes Or have a sound, or shift offset can change in temperature of the working environment to avoid greatly affect the sensor chip, there is an advantage that good can perform pressure measurements.

According to the second aspect of the present invention, the tip protecting fluid is a fluorine-based oil and the external pressure transmitting member is a gel-like material. Inactive, can suppress the corrosion of the sensor chip, can achieve good electrical insulation between the sensor chip, fluorine-based oil has a higher specific gravity than the gel body, both are not mixed, There is an advantage that the expected function can be performed for a long period of time.

According to the third aspect of the present invention, since the chip protection fluid is a magnetic fluid, in addition to the effect of the first aspect, the breakage of the sensor chip can be confirmed by an external magnetic field, and the self-diagnosis of the sensor chip can be performed. There is an advantage of performing. According to the fourth aspect of the invention, since the external pressure transmitting member is a ring-shaped permanent magnet, the external pressure transmitting member is a ring-shaped permanent magnet as compared with the case where the external pressure transmitting member is formed into a gel-like body. There are advantages.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

2A is a front view, FIG. 2B is a rear view, and FIG. 2C is a partial sectional view.

FIG. 3 is a partial schematic sectional view.

FIG. 4 is a partial perspective view of another embodiment.

FIG. 5 is a sectional view of a conventional example.

FIG. 6 is a sectional view of another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor chip 2 Pressure introduction port 3 Chip protection fluid 4 Gel body 5 Casing 6 External pressure transmission member 7 Magnetic fluid 8 Permanent magnet

Claims (4)

[Claims] 1. A pressure sensor for detecting a pressure by applying a measurement fluid pressure to a built-in sensor chip from a pressure inlet formed in a casing, and contacting the sensor chip inside the pressure inlet. A pressure sensor comprising a chip protection fluid filled therein, and an outside pressure transmitting member for sealing the chip protection fluid filled outside the chip protection fluid. 2. The pressure sensor according to claim 1, wherein the tip protection fluid is a fluorine-based oil, and the external pressure transmitting member is a gel. 3. The pressure sensor according to claim 1, wherein the chip protection fluid is a magnetic fluid. 4. The pressure sensor according to claim 1, wherein the external pressure transmitting member is a ring-shaped permanent magnet, and a magnetic fluid is held inside the ring-shaped permanent magnet.