JP2000162074A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor in which a pressure transmission medium is not stripped from the tube sidewall of a pressure receiving part even when a positive pressure and a negative pressure are loaded repeatedly and by which a pressure can be measured correctly. SOLUTION: This pressure sensor is provided with a pressure receiving part 12 which comprises a through hole 12b to be formed in a nearly bottomed tube shape, in which a tube bottom part 12a and a tube inside part 12c are formed and in which a pressure transmission medium 13 used to transmit a received pressure is filled into the tube inside part 12c. In addition, it is provided with a sensor element 2 in which a pressure introduction pipe 22 installed so as to protrude from a sensor body 21 is inserted into, and passed through, the through hole 12b at the pressure receiving part 12 and in which a pressure introduced via the pressure transmission medium 13 is converted into an electric signal. The pressure sensor is constituted in such a way that a seal part 3 which is bonded to the outer circumferential part 22a of the pressure introduction pipe 22 and to the sidewall of the through hole 12b and which isolates the pressure transmission medium 13 at the pressure receiving part 12 from the air is installed in an outer-circumferential-part gap 22d which is formed between the outer circumferential part 22a and the sidewall.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor used for a washing machine or a boiler, for example, for measuring the pressure of water to be measured via a pressure transmitting medium.

[0002]

2. Description of the Related Art Conventionally, as a pressure sensor of this type, FIG.
There exists a thing of a structure shown in FIG. The pressure receiving portion A is formed in a substantially cylindrical shape having a bottom and has a cylindrical bottom portion A1 having a cylindrical interior and a through hole, and a pressure receiving portion A filled with a pressure transmitting medium B for transmitting received pressure; A pressure introducing pipe C2 protruding from C1 is inserted into a through hole of the pressure receiving portion A, and has a sensor element C for converting the pressure introduced through the pressure transmitting medium B into an electric signal.

More specifically, when measuring the water pressure, when the semiconductor pressure sensor chip built in the sensor body C1 comes into contact with water, the semiconductor pressure sensor chip is corroded by components contained in the water. Therefore, the pressure is measured via the pressure transmission medium B so as not to directly contact the water. That is, the pressure transmission medium B is composed of a silicone oil B1 that does not corrode the semiconductor pressure sensor chip, and an elastic silicone gel B2 laminated on the silicone oil B1. Then, while the silicon oil B1 protects the semiconductor pressure sensor chip from corrosion, the silicon gel B2 is heated and thermally hardened from a liquid to form a pressure receiving surface B21, and the pressure of the water to be measured is applied to the pressure receiving surface B21. I do.

[0004] Further, an O-ring (O-ring) D is provided between the outer peripheral portion C21 of the pressure introducing pipe C2 and the side wall of the cylinder bottom portion A1 by nitrile rubber or acrylic rubber or the like, and is in close contact with the outer peripheral portion C21 and the side wall. As a result, the pressure transmission medium B of the pressure receiving portion A is isolated from the atmosphere, and the silicon oil B1 is prevented from flowing out. Where O-ring D
When a positive pressure or a negative pressure is repeatedly applied to the pressure receiving surface B21 of the pressure transmission medium B, the outer peripheral portion C is generated by a pressure difference from the atmospheric pressure.
Move in close contact with 21.

[0005]

In the above-mentioned conventional pressure sensor, the O-ring D separates the pressure transmitting medium B of the pressure receiving portion A from the atmosphere and prevents the silicon oil B1 from flowing out, so that the applied hydraulic pressure is reduced. Can be measured via the pressure transmission medium B.

However, when the positive pressure and the negative pressure are repeatedly applied to the pressure receiving portion A, the movement of the O-ring D causes the atmosphere to come from the outside through the outer peripheral portion C21 of the pressure introducing pipe C2 and further to the silicon oil B1. There is a problem that the silicon gel B2 enters the silicon gel B2 and is separated from the side wall of the cylinder of the pressure receiving portion A without being able to withstand the load repeatedly due to the air bubbles in the silicon gel B2.

Further, when the silicon gel B2 is thermally cured from a liquid state, a harmful gas containing sulfur and the like generated from the O-ring D enters through the air introduction port and is inhibited from being thermally cured. There is a problem in that it cannot be withstood and peels off from the side wall of the pressure receiving portion A.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to allow a pressure transmission medium to separate from a cylinder side wall of a pressure receiving portion even when a positive pressure and a negative pressure are repeatedly applied. An object of the present invention is to provide a pressure sensor capable of transmitting pressure correctly to a sensor element without using the pressure sensor.

[0009]

According to a first aspect of the present invention, there is provided a cylinder having a substantially bottomed cylindrical shape having a cylindrical bottom portion having an inner portion and a through hole. The pressure-receiving portion filled with a pressure-transmitting medium for transmitting the pressure and the pressure-introducing pipe protruding from the sensor body are inserted through the through-hole of the pressure-receiving portion, and the pressure introduced through the pressure-transmitting medium is transmitted as an electric signal. A pressure sensor having a sensor element that converts the pressure transmitting medium into a pressure transmitting medium and a pressure transmitting medium of the pressure receiving portion that is isolated from the atmosphere by adhering to an outer peripheral portion of the pressure introducing pipe and a side wall of the through hole. It is configured to be provided in an outer peripheral gap formed between them.

According to a second aspect of the present invention, in the first aspect, the seal portion is cured from a liquid state, and the pressure introducing pipe of the sensor element has a tapered shape so as to reduce the outer peripheral gap. Is fitted in the through-hole formed in the hole.

According to a third aspect of the present invention, in the second aspect, a communication space communicating with the outer peripheral gap is provided at a bottom of the pressure receiving portion.

According to a fourth aspect of the present invention, in the second aspect, a liquid sealing portion is injected into a cylinder of the pressure receiving portion, and a ring-shaped flat plate is provided in the pressure introducing pipe. It has a through-hole that engages with a base end protruding from the sensor body and is provided at the bottom of the pressure receiving portion.

According to a fifth aspect of the present invention, in the first or second aspect, an air discharge port having one end communicating with the gap at the outer peripheral portion and the other end communicating with the atmosphere is provided at the bottom of the pressure receiving portion. Configuration.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the seal portion is formed with a silicone adhesive.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

Reference numeral 1 denotes a body, which is formed of resin or metal into a substantially rectangular parallelepiped shape and has a housing space 1a therein, and is provided integrally with the body body 11 to form a substantially bottomed cylindrical shape. Pressure receiving portion 12 and pressure transmitting medium 13
And is configured. The pressure receiving portion 12 is provided with a cylindrical bottom portion 12a having a through hole 12b, and a cylindrical inner portion 12c formed in a circular shape and surrounded by a cylindrical side wall. The through hole 12b communicates with the cylindrical inner portion 12c and the housing space 1a. It is formed in a tapered shape having a larger width toward the accommodation space 1a.

The pressure transmitting medium 13 is a silicon gel 13a,
And a liquid silicone oil 13b laminated on the silicon gel 13a, and is filled in the cylinder interior 12c of the body 1. The silicon gel 13a is a gel having elasticity containing silicon, has excellent heat resistance, and has a small change in elasticity due to temperature from a low temperature to a high temperature. Opposed pressure receiving surface 1
3c is formed, the pressure of the water to be measured, that is, the water pressure is received by the pressure receiving surface 13c, and the water pressure is transmitted to the silicon oil 13b.

Reference numeral 2 denotes a sensor element.
1, a pressure introducing pipe 22 and a sensor terminal 23 are provided. The sensor body 21 is provided in the housing space 1 of the body body 11.
a silicon pressure sensor chip (not shown) made of a silicon semiconductor provided with a silicon diaphragm provided therein. The piezoresistor formed in the silicon diaphragm changes its resistance value when a water pressure is applied thereto. Converts pressure into an electrical signal.

The pressure introducing pipe 22 is formed of a resin or a metal and has a tubular shape having an outer peripheral portion 22a and a pressure introducing hole 22b. A base end portion 22c protrudes from the sensor body 21, and the outer peripheral portion 22a is formed at the base end portion. The pressure receiving portion 12 which is formed in a tapered shape having a larger width toward the side 22c, and similarly formed in a tapered shape.
The outer peripheral gap 22d is formed between the outer peripheral part 22a and the side wall of the through hole 12b. Then, the silicon oil 13b is filled in the pressure introducing hole 22b, and a water pressure is introduced through the silicon oil 13b and transmitted to the semiconductor pressure sensor chip.

The sensor terminal 23 is made of copper or copper alloy.
An amplifying element (not shown), which is electrically connected to the semiconductor pressure sensor chip and arranged on both sides of the sensor main body 21 and has an amplifying circuit, and a thick film resistor (not shown) for temperature compensation are formed. Connected to the printed circuit board 4.

Reference numeral 3 denotes a seal, which is a silicone adhesive manufactured by Shin-Etsu Chemical Co., Ltd. (product number KE-1843), which contains silicon and is thermally cured from a liquid when heated. In the liquid state, the seal portion 3 is injected into the cylinder interior 12c of the pressure receiving portion 12, and is filled into the outer peripheral gap 22d and the cylinder interior 12c on the cylinder bottom 12a side of the body 1, respectively.

At this time, the through hole 12b of the pressure receiving portion 12 is formed in a tapered shape, and the pressure introducing pipe 22 is similarly formed in a tapered shape and is press-fitted in a state fitted in the through hole 12b. The gap 22d is reduced, and is prevented from flowing out of the outer gap 22d to the accommodation space 1a side. Then, it is heated and thermally hardened from a liquid, and is disposed in the outer peripheral gap 22d in a state of being adhered to the outer peripheral portion 22a of the pressure introducing pipe 22 and the side wall of the through hole 12b.
The second pressure transmission medium 13 is isolated from the atmosphere.

The operation of the above will be described. Positive or negative water pressure is repeatedly applied to the pressure receiving surface 13c of the pressure transmission medium 13 to fill the pressure transmission medium 13 filled in the cylinder interior 12c.
To the semiconductor pressure sensor chip of the sensor element 2 via the

At this time, the seal portion 3 is provided with the outer peripheral portion gap 22d.
And is bonded to the outer peripheral portion 22a and the side wall of the through hole 12b over a wide bonding area, so that the movement resistance is increased and the movement is prevented by the pressure difference from the atmospheric pressure, and the atmosphere is reduced. This prevents the pressure receiving medium 12 from entering the pressure transmitting medium 13 from the housing space 1a side.

When a water pressure is applied to the sensor element 2 via the pressure transmitting medium 13, the silicon diaphragm bends, and the resistance value of the piezoresistor formed on the silicon diaphragm changes in proportion to the amount of the deflection. . And
This resistance value is subjected to temperature compensation using the resistance value of the thick film resistor provided on the printed circuit board 4, and then the electric signal is amplified by an amplification element to measure the water pressure.

In the pressure sensor according to the first embodiment, as described above, the seal portion 3 for isolating the pressure transmitting medium 13 of the pressure receiving portion 12 from the atmosphere is formed between the outer peripheral portion 22a and the side wall. Since it is provided in the gap 22d, the pressure introduction pipe 22
Of the through hole 12b of the pressure receiving portion 12 is large, so that even if the pressure receiving portion 12 is repeatedly subjected to the positive pressure and the negative pressure, the sealing portion 3
Is prevented from moving based on the pressure difference from the atmospheric pressure, and the pressure transmitting medium 13 can be prevented from being separated from the cylinder side wall of the pressure receiving portion 12 due to the invasion of the atmosphere.

Further, since the through hole 12b of the pressure receiving portion 12 is formed in a tapered shape and the pressure introducing pipe 22 is fitted into the through hole 12b, the outer peripheral gap 22d is reduced, and the liquid seal portion 3 is formed. Outflow from the outer peripheral gap 22d can be prevented.

Also, unlike the O-ring made of nitrile rubber or acrylic rubber, the sealing portion 3 is made of a silicone adhesive, so that it does not release harmful gas containing sulfur or the like. The hardening of the pressure transmission medium 13 is not hindered by the intrusion, and high reliability can be achieved.

In the first embodiment, the seal portion 3 is formed with a silicone adhesive. However, the seal portion 3 formed of another material may be provided in the outer circumferential gap 22d, and there is no limitation.

In the first embodiment, the pressure transmitting medium 1
3 is composed of the silicon gel 13a and the silicone oil 13b, but the material is not limited.

A second embodiment of the present invention will be described below with reference to FIGS. In the second embodiment, functions different from those in the first embodiment will be described, and members having substantially the same functions as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

In the second embodiment, a communication space 12d communicating with the outer peripheral gap 22d is provided by cutting out the inner peripheral portion of the cylinder bottom portion 12a of the pressure receiving portion 12 so as to inject into the cylinder interior 12c of the pressure receiving portion 12. The liquid seal portion 3 thus introduced is introduced into the communication space 12d and accumulated therein.

In the pressure sensor of the second embodiment, as described above, the communication space 12d communicating with the outer circumferential gap 22d is provided in the cylinder bottom 12a of the pressure receiving section 12, so that the inside of the cylinder of the pressure receiving section 12 is provided. The liquid seal portion 3 injected into the seal portion 12c is collected in the communication space 12d, and is sealed.
Can be reliably prevented from flowing out of the outer space 22d into the housing space 1a.

A third embodiment of the present invention will be described below with reference to FIG. In the third embodiment, functions different from those in the first embodiment will be described, and members having substantially the same functions as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

In the third embodiment, the flat plate 12e is provided on the cylinder bottom 12a of the pressure receiving portion 12, is formed in a ring shape having a through hole 12e1, and the through hole 12e1 is Engaging with the portion 22c,
The liquid seal part 3 injected into the surface is adhered to one surface and stored.

In the pressure sensor according to the third embodiment, as described above, the through-hole in which the ring-shaped flat plate 12e is engaged with the base end portion 22c of the pressure introducing pipe 22 protruding from the sensor body 21. 12b, the cylinder bottom 1 of the pressure receiving section 12
2a, the liquid seal portion 3 injected into the cylinder interior 12c of the pressure receiving portion 12 is collected on one surface of the flat plate 12e, and reliably prevents the seal portion 3 from flowing out of the outer peripheral gap 22d. it can.

A fourth embodiment of the present invention will be described below with reference to FIG. In the fourth embodiment, functions different from those in the first embodiment will be described. Members having substantially the same functions as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

In the fourth embodiment, the air outlets 12f are provided at both sides of the cylinder bottom 12a with respect to the through holes 12b.
One end communicates with the outer peripheral gap 22d and the other end communicates with the atmosphere. When a large positive pressure and a large negative pressure are repeatedly applied to the pressure receiving portion 12, even if the seal portion 3 slightly moves due to a pressure difference from the atmospheric pressure, the sucked air is discharged and the pressure receiving portion 12 is discharged. The liquid sealing portion 3 which does not enter the pressure transmitting medium 13 and is injected into the cylinder interior 12c.
Custody.

In the pressure sensor according to the fourth embodiment, as described above, the air discharge port 12f having one end communicating with the outer peripheral gap 22d and the other end communicating with the atmosphere is connected to the pressure receiving section 12d.
Large pressure of the positive pressure and the negative pressure is repeatedly applied to the pressure receiving portion 12 so that the sealing portion 3
Even if the air moves slightly due to the pressure difference from the atmospheric pressure, the sucked air is exhausted from the air exhaust port 12f and
The liquid seal portion 3 which does not enter the pressure transmission medium 13 of
It is possible to prevent the water from being collected by the f and flowing out of the outer peripheral gap 22d.

[0040]

According to the first aspect of the present invention, an outer peripheral gap formed between an outer peripheral portion of the pressure introducing pipe and a side wall of the through hole in the pressure receiving portion has a seal portion for isolating the pressure transmitting medium of the pressure receiving portion from the atmosphere. Since the adhesive area adhered to the outer peripheral portion and the side wall of the through hole is large compared to the conventional O-ring contact area, even if a positive pressure and a negative pressure are repeatedly applied to the pressure receiving portion, the sealing is performed. The movement based on the pressure difference from the atmospheric pressure of the pressure receiving portion is prevented, and the pressure transmitting medium can be prevented from being separated from the cylinder side wall of the pressure receiving portion due to the invasion of the atmosphere.

According to a second aspect of the present invention, in addition to the effects of the first aspect, if the sealing portion is cured from a liquid state, the through hole of the pressure receiving portion is formed in a tapered shape and the pressure is introduced. Since the pipe is fitted into the through hole, the outer peripheral gap is reduced, and the liquid seal portion can be prevented from flowing out of the outer peripheral gap.

According to the third aspect, in addition to the effect of the second aspect, the communication space communicating with the outer peripheral gap is provided at the bottom of the pressure receiving portion, so that the liquid seal portion is caught in the communication space. As a result, it is possible to reliably prevent the seal portion from flowing out of the outer peripheral portion gap.

According to the fourth aspect, in addition to the effect of the second aspect, if the liquid seal portion is injected into the cylinder of the pressure receiving portion, the ring-shaped flat plate is removed from the sensor main body. Since the through hole is provided at the bottom of the pressure receiving portion and has a through hole that engages with the base end of the pressure introducing tube, the liquid seal portion injected into the cylinder of the pressure receiving portion is collected on one surface of the flat plate. As a result, it is possible to reliably prevent the seal portion from flowing out of the outer peripheral portion gap.

According to a fifth aspect of the present invention, in addition to the effects of the first or second aspect, an air discharge port having one end communicating with the outer peripheral gap and the other end communicating with the atmosphere is provided at the bottom of the pressure receiving portion. Therefore, even if a large positive pressure and a negative pressure are repeatedly applied to the pressure receiving portion and the seal portion slightly moves due to a pressure difference from the atmospheric pressure, the atmosphere is exhausted from the air outlet and the pressure transmission of the pressure receiving portion is performed. It is possible to prevent the liquid seal portion from being caught in the air outlet and flowing out of the outer peripheral gap without entering the medium.

According to a sixth aspect of the present invention, in addition to the effects of any one of the first to fifth aspects, a nitrile rubber or an acrylic rubber is used as a material because the seal portion is formed with a silicone adhesive. Unlike the O-ring described above, since no harmful gas containing sulfur or the like is released, the hardening of the pressure transmission medium is not hindered by the intrusion of the harmful gas, and high reliability can be achieved.

[Brief description of the drawings]

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

FIG. 2 is a front sectional view showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional perspective view showing a cylinder bottom of the pressure receiving unit.

FIG. 4 is a front sectional view showing a third embodiment of the present invention.

FIG. 5 is a front sectional view showing a fourth embodiment of the present invention.

FIG. 6 is a front sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body 11 Body main body 12 Pressure receiving part 12a Tube bottom part 12b Through hole 12c Inside of cylinder 12d Communication space 12e Flat plate 12f Air outlet 13 Pressure transmission medium 2 Sensor element 21 Sensor main body 22 Pressure introducing pipe 22a Outer peripheral part 22b Pressure introducing hole 22c base End 22d Outer circumference gap 3 Seal

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[Procedure amendment]

[Submission date] December 2, 1998 (1998.12.
2)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 3

FIG. 2

FIG. 4

FIG. 5

FIG. 6

Claims (6)

[Claims] 1. A pressure receiving portion, which is formed in a substantially bottomed cylindrical shape and has a cylindrical bottom portion having a cylindrical inner portion and a through hole, and a pressure transmitting medium for transmitting received pressure and filled in the cylindrical portion, and a protruding portion from the sensor body. A pressure sensor having a sensor element that converts a pressure introduced through a pressure transmission medium into a pressure introducing pipe through a through-hole of the pressure receiving unit and converts the pressure into an electric signal. A pressure sensor, wherein a seal portion that adheres to a side wall of the through hole and separates the pressure transmitting medium of the pressure receiving portion from the atmosphere is provided in an outer peripheral portion gap formed between the outer peripheral portion and the side wall. 2. The method according to claim 1, wherein the seal portion is cured from a liquid state, and the pressure introducing pipe of the sensor element is fitted in the tapered through hole so as to reduce the gap at the outer peripheral portion. The pressure sensor according to claim 1, wherein: 3. A communication space communicating with the outer peripheral portion gap,
The pressure sensor according to claim 2, wherein the pressure sensor is provided at a bottom of the cylinder of the pressure receiving unit. 4. A through-hole in which a liquid seal portion is injected into the cylinder of the pressure receiving portion, wherein a ring-shaped flat plate is engaged with a base end portion of the pressure introducing pipe projecting from the sensor main body. The pressure sensor according to claim 2, wherein the pressure sensor has a hole and is provided at a bottom of the pressure receiving portion. 5. The pressure sensor according to claim 1, wherein an air discharge port having one end communicating with the outer peripheral portion gap and the other end communicating with the atmosphere is provided at a bottom of the pressure receiving portion. . 6. The pressure sensor according to claim 1, wherein said seal portion is formed with a silicone adhesive.