JPH11183288A - Capacitance type pressure sensor unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a capacitance type pressure sensor unit capable of reducing the number of used sealing members. SOLUTION: The capacitance type pressure sensor unit has a pressure sensor element 3, a connector 12 and a containing case 4. The element 3 is contained in the case 4 so that the pressure sensing surface 1a of a first base 1 having insulation properties is opposed to the bottom wall 4a of the case 4, a fluid chamber 7 is formed between the surface 1a and the wall 4a and a large gap 6 is not formed between the surface 1a and a peripheral wall 4b. A connector body 13 of the connector 12 is contained at least at its base part 13a in the case 4. An O-ring 21 is disposed between the base part 13a of the body 13 and an annular sealing member containing space 20 surrounded by the wall 4b of the case 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type pressure sensor unit for detecting pressure based on a change in capacitance.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a conventional capacitance type pressure sensor unit of this type.

This capacitance type pressure sensor unit has a pressure sensor element 3 which is formed by providing electrodes on opposing surfaces of a first insulating base 1 and a second insulating base 2 respectively. . The pressure sensor element 3 is housed in a metal housing case 4. The storage case 4 has a bottom wall 4a in which a fluid inlet 5 for introducing a fluid to be measured is formed.
And a peripheral wall 4b having one end connected to the bottom wall 4a.

In the peripheral wall 4b of the storage case 4, the pressure sensor element 3 has its pressure sensing surface 1a opposed to the bottom wall 4a so as not to form a large gap 6 with the peripheral wall 4b. It is stored. Between the pressure sensing surface 1a of the pressure sensor element 3 and the bottom wall 4a, there is provided a fluid chamber 7 into which the fluid to be measured enters. A backup ring 8 is disposed on the inner periphery of the peripheral wall 4b between the pressure sensing surface 1a and the bottom wall 4a, and a pressure is applied from the fluid chamber 6 through the gap 6 while being backed up by the backup ring 8. A seal member 9 such as an O-ring for preventing leakage of the measurement fluid is provided.

[0005] On the surface of the second insulating substrate 2 of the pressure sensor element 3, an electronic circuit element 10 such as an integrated circuit for detecting a capacitance between opposing electrodes in the pressure sensor element 3 is disposed. The electronic circuit element 10 is connected by soldering to each electrode of a wiring pattern provided on the surface of the second insulating substrate 2. Each electrode portion on one end side of the wiring pattern of the flexible printed board 11 is connected by soldering to the wiring pattern provided on the surface of the second insulating base 2.

On the surface of the second insulating base 2 surrounding the electronic circuit element 10 in the peripheral wall 4b of the storage case 4, a cylindrical body of a connector body (connector housing) 13 made of insulating resin of the connector 12 is provided. The base 13a is overlapped with its end face in contact. A metal support ring 14 is interposed between the base 13 a of the connector body 13 and the peripheral wall 4 b of the storage case 4. This support ring 14 is received on the surface of the second insulating substrate 2. A seal member 15 such as an O-ring supported by a groove on the outer periphery of the support ring 14 is interposed between the support ring 14 and the peripheral wall portion 4b of the storage case 4 for sealing. The base 13a of the connector body 13 and the support ring 14 are also sealed with a seal member 16 such as an O-ring interposed.

The connector 12 is fixed to the storage case 4 by pressing the outer periphery of the base 13a of the connector body 13 by crimping the end 4d of the storage case 4 as shown in the drawing. Each of the connector terminals 17 of the connector 12 penetrates through each of the electrode portions on the other end of the wiring pattern of the flexible printed circuit board 11 and is connected to these electrode portions by soldering.

In such a capacitive pressure sensor unit, when a pressure-measuring fluid such as a gas or a liquid enters the fluid chamber 7 through the fluid inlet 5, the pressure of the pressure-measuring fluid is reduced by the first insulation of the pressure sensor element 3. Acts on the pressure sensing surface 1a of the conductive substrate 1, thereby changing the capacitance between the opposing electrodes in the pressure sensor element 3, and the change in the capacitance is detected by the electronic circuit element 10 and is transmitted through the connector 12 to the outside. Is to be conveyed to. At this time, the gap 6 between the pressure sensor element 3 and the peripheral wall 4b is sealed by the seal member 9 so that the fluid in the fluid chamber 7 does not leak. Further, the seal member 9 is deformed by high fluid pressure and enters the gap 6 between the pressure sensor element 3 and the peripheral wall portion 4b to be backed up by the backup ring 8 so that the seal is not broken.

[0009]

However, in the conventional capacitance type pressure sensor unit having such a structure,
A sealing member 9 for preventing leakage of the pressure-measured fluid from the fluid chamber 7 through the gap 6, a base 13 a of the connector body 13 and a peripheral wall 4 b of the storage case 4 from the outside
Since the seal members 15 and 16 are used to prevent water or the like from entering through the gap between the seal members, the number of seal members to be used increases, and there is a problem that the cost increases.

A conventional structure in which a sealing member 9 is disposed between the pressure sensing surface 1a of the first insulating substrate 1 of the pressure sensor element 3 and the bottom wall 4a of the storage case 4 in the fluid chamber 7 In the case where a sudden large pressure acts on the pressure sensing surface 1a in the fluid chamber 7 in a direction orthogonal to the pressure sensing surface 1a,
a had a problem that a force acting in a direction in which the seal was broken away from the seal member 9 was applied.

An object of the present invention is to provide a capacitance type pressure sensor unit capable of reducing the number of seal members used.

Another object of the present invention is to provide a capacitance type pressure sensor unit which can prevent a seal from being broken even when a sudden large pressure acts on a pressure sensing surface in a fluid chamber in an orthogonal direction. It is in.

[0013]

The capacitance type pressure sensor unit to be improved in the present invention has a pressure sensor element for detecting the pressure of a fluid to be measured. This pressure sensor element has a first insulating substrate having an electrode on a front surface and a back surface serving as a pressure sensing surface, and an electrode opposed to the electrode of the first insulating substrate at a predetermined interval. It comprises a second insulating substrate combined with one insulating substrate. Further, a storage case for storing the pressure sensor element is provided. The storage case includes a bottom wall having a fluid inlet for introducing a fluid to be measured, and a peripheral wall having one end connected to the bottom wall. The pressure sensor element is placed in the storage case so as to oppose the bottom wall and not to form a large gap between the pressure sensor element and the peripheral wall. It is housed so as to form a fluid chamber into which the measurement fluid enters. A seal member is provided in the storage case to prevent the fluid in the fluid chamber from leaking through the gap between the pressure sensor element and the storage case. Further, at least the base of the connector body made of insulating resin of the connector is housed in the housing case, and is brought into contact with the surface of the second insulating base of the pressure sensor element.

In the capacitance type pressure sensor unit according to the present invention, an annular sealing member housing surrounded by the second insulating base of the pressure sensor element, the base of the connector body of the connector, and the peripheral wall of the housing case. A space is formed. The seal member is formed of an O-ring that is housed in the seal member housing space and contacts the second insulating base, the base of the connector body, and the peripheral wall of the housing case. The O-ring in the present invention is not limited to a circular cross-sectional shape, but also includes a non-circular cross-sectional shape.

With such a structure, the seal on the fluid chamber side and the seal between the connector body and the storage case can be used in common, and the number of seal members used can be reduced. Also, even if a suddenly large pressure is applied to the pressure sensing surface by the fluid to be measured in the fluid chamber in a direction orthogonal to the pressure, the sealing member is arranged on the opposite side to the pressure sensing surface where the pressure acts, so that the pressure The seal can be prevented from being broken by the pressure acting on the sensing surface.

Next, a more specific configuration of the capacitance type pressure sensor unit will be described. In this case, the pressure sensor element in the capacitance type pressure sensor unit to be improved includes a first insulating substrate having electrodes on the front surface and a back surface serving as a pressure sensing surface, and a first insulating substrate formed of the first insulating substrate. The first electrode having an electrode on the back surface facing the electrode at a predetermined interval.
And the second insulating substrate combined with the insulating substrate. The connector is arranged such that the end face of the base of the connector body made of insulating resin is in contact with the surface of the second insulating base of the pressure sensor element. The metal storage case includes a bottom wall having a fluid inlet for introducing a fluid to be measured, and a peripheral wall having one end connected to the bottom wall. The pressure sensor element is housed in the housing case such that the pressure sensing surface of the first insulating substrate faces the bottom wall and does not form a large gap with the peripheral wall. The base of the connector body is housed, and the base of the connector body is prevented from coming off by caulking applied to the end of the peripheral wall of the housing case. Between the pressure sensing surface of the first insulating substrate of the pressure sensor element and the bottom wall of the storage case, a fluid chamber for receiving a fluid to be measured under pressure is formed. A seal member is provided to prevent the fluid in the fluid chamber from leaking through a gap between the pressure sensor element and the peripheral wall of the storage case.

In the capacitance type pressure sensor unit having such a configuration, an annular tapered surface whose diameter decreases toward the end surface is formed between the end surface and the outer peripheral surface at the base of the connector body. . An annular seal member storage space is formed between the tapered surface of the base of the connector body, the peripheral wall of the storage case, and the second insulating base of the pressure sensor element. The sealing member is formed of an O-ring that is housed in the sealing member housing space and contacts the annular tapered surface, the second insulating base, and the inner surface of the peripheral wall of the housing case.

With such a structure, the sealing member made of the O-ring is placed in the storage case in the second direction opposite to the pressure sensing surface on the back surface of the second insulating substrate of the pressure sensor element.
Can be easily arranged on the outer periphery on the front side of the insulating substrate. For this reason, it is possible to prevent the seal from being broken even if the pressure-measuring fluid suddenly acts on the pressure sensing surface of the pressure sensor element in the fluid chamber in a direction perpendicular to the pressure.

In such a capacitance type pressure sensor unit, the second insulating base is provided between the surface of the second insulating base of the pressure sensor element and the outer peripheral surface of the second insulating base. It is preferable to form an annular tapered surface whose diameter decreases toward the surface of the base. With this configuration, the seal member is moved from the fluid chamber side to the seal member by the pressure of the pressure-measuring fluid acting on the seal member, and the tapered surface of the second insulating base, the tapered surface of the base of the connector body, and the housing case. By making good contact with the inner surface of the peripheral wall portion, sealing can be reliably performed.

In the seal member storage space, an annular tapered surface formed at the base of the connector main body and the inner surface of the peripheral wall of the storage case are brought into contact with each other, and the outer peripheral surface of the base of the connector main body and the storage case are formed. It is preferable to store a backup ring that prevents the O-ring from entering a gap formed between the inner surface of the peripheral wall and the inner surface of the peripheral wall. With this configuration, even if a large pressure of the fluid to be measured acts from the fluid chamber side,
It is possible to reliably prevent the seal from being broken by the O-ring entering the gap formed between the outer peripheral surface of the base of the connector main body and the inner surface of the peripheral wall of the storage case.

[0021]

FIG. 1 is a longitudinal sectional view of a first example of an embodiment of a capacitance type pressure sensor unit according to the present invention.

In the capacitance type pressure sensor unit, the pressure sensor element 3 used for detecting the pressure of the fluid to be measured has an electrode (not shown) on the inwardly facing surface and a reverse side. A first insulating substrate 1 made of ceramic and having a thickness of about 0.4 to 0.8 mm serving as a pressure sensing surface 1a.
And a second insulating substrate 2 made of ceramic combined with the first insulating substrate 1 having an electrode (not shown) on the back surface facing the electrode of the first insulating substrate 1 at a predetermined interval. It is composed of The distance between the opposing electrodes in the pressure sensor element 3 varies depending on the pressure acting on the pressure sensing surface 1a, and a change in pressure appears as a change in capacitance.

Such a pressure sensor element 3 is housed in a metal housing case 4. The storage case 4 includes a bottom wall 4a having a fluid inlet 5 for introducing a fluid to be measured under pressure, and a peripheral wall 4b having one end connected to the bottom wall 4a.
And a cylindrical portion 4c surrounding the fluid inlet 5 and provided continuously at the center of the bottom wall portion 4a. In the peripheral wall portion 4b of such a storage case 4, the pressure sensor element 3
The pressure sensing surface 1a of the insulating substrate 1 is housed so as not to form a large gap 6 between the bottom wall 4a and the peripheral wall 4b. The pressure sensing surface 1a of the first insulating substrate 1 of the pressure sensor element 3 and the bottom wall 4 of the storage case 4
A fluid chamber 7 into which the fluid to be measured enters is formed between the fluid chamber 7 and the fluid chamber 7. The fluid chamber 7 is formed by depressing the surface of the bottom wall 4a of the storage case 4 facing the pressure sensing surface 1a of the first insulating substrate 1.

In the peripheral wall portion 4b of the storage case 4, on the surface of the second insulating substrate 2 of the pressure sensor element 3, a CMOSI for detecting the capacitance between the opposing electrodes in the pressure sensor element 3 is provided.
An electronic circuit element 10 made of C or the like is arranged. The electronic circuit element 10 is connected by soldering to a wiring pattern (not shown) provided on the surface of the second insulating substrate 2. To the wiring pattern provided on the surface of the second insulating substrate 2, an electrode part in the wiring pattern of the flexible printed board 11 is connected by soldering. Thereby, each electrode of the electronic circuit element 10 is connected to each connector terminal 17 of the connector 12 via the flexible printed circuit board 11. That is, each connector terminal 1 of the connector 12
Reference numeral 7 penetrates through the respective electrode portions on the other end side of the wiring pattern of the flexible printed board 11 and is connected to these electrode portions by soldering.

The outer surface of the second insulating substrate 2 surrounding the electronic circuit element 10 in the peripheral wall portion 4b of the storage case 4 has an end surface of the cylindrical base 13a of the connector body 13 made of insulating resin of the connector 12. Are superimposed. The outer periphery of the base 13a of the connector body 13 is arranged so as to contact the inner surface of the peripheral wall 4b of the storage case 4 without the support ring 15 shown in FIG. The connector 12 is configured such that the outer periphery of the base 13 a of the connector body 13 is
It is fixed to the storage case 4 by caulking c.

The surface 2 of the second insulating substrate 2 of the pressure sensor element 2 facing the end face of the base 13a of the connector body 13
a and the outer peripheral surface 2b are formed on the outer peripheral portion on the outer peripheral side.
An annular tapered surface 18 whose diameter is reduced from the b side toward the surface 2a is formed. Also, the second insulating substrate 2
The outer peripheral surface formed by the end surface 13a1 of the base 13a of the connector body 13 and the outer peripheral surface 13a2 facing the surface 2a of the connector body 13 has an annular tapered surface 19 tapering in diameter from the outer peripheral surface 13a2 toward the end surface 13a1. It is formed so as to face the surface 18. An annular seal member storage space 2 is provided between the tapered surfaces 18 and 19 and the peripheral wall portion 4b of the storage case 4.
0 is formed. In the seal member storage space 20, the O-ring 21 as a seal member is brought into contact with the tapered surfaces 18, 19 and the inner surface of the peripheral wall portion 4b of the storage case 4.
Is arranged.

With such a structure, the seal on the fluid chamber 7 side and the seal between the connector body 13 and the storage case 14 can be shared by the O-ring 21, and the number of seal members used can be reduced. Further, even if the pressure-measured fluid suddenly acts on the pressure sensing surface 1a in the fluid chamber 7 in a direction perpendicular to the pressure, the pressure sensing surface 1a on which the pressure acts.
Since the O-ring 21 as the seal member is disposed on the opposite side, the seal can be prevented from being broken by the pressure acting on the pressure sensing surface 1a.

The sealing member housing space 20 has a tapered surface 18 provided on the second insulating base 2, a tapered surface 19 provided on the base 13 a of the connector body 13, and a peripheral wall 4 b of the storage case 4. O-ring 21 as a seal member from the fluid chamber 7 side because it is formed by the inner surface.
O-ring 21 at the pressure of the fluid to be measured
The tapered surface 18 of the second insulating base 2, the tapered surface 19 of the base 13a of the connector body 13, and the storage case 4
Satisfactorily in contact with the inner surface of the peripheral wall portion 4b, and sealing can be reliably performed.

FIG. 2 is a vertical sectional view of a main part of a second example of the embodiment of the capacitance type pressure sensor unit according to the present invention. Note that parts corresponding to those in FIG. 1 described above are denoted by the same reference numerals.

In this capacitance type pressure sensor unit,
In the seal member storage space 20, the annular tapered surface 18 formed in the base 13a of the connector main body 13 and the inner surface of the peripheral wall 4b of the storage case 4 are brought into contact with each other.
Outer peripheral surface 13a2 of base 13a and peripheral wall 4 of storage case 4
A back-up ring 22 for preventing the O-ring 21 from entering a gap formed between the back ring 22 and the inner surface of the b is stored. Other configurations are the same as those of the first example shown in FIG.

When the backup ring 22 is provided in this manner, even if a large pressure of the fluid to be measured acts from the fluid chamber 7 side, the outer peripheral surface 13a of the base 13a of the connector body 13 can be used.
It is possible to reliably prevent the O-ring 21 from entering the gap 23 formed between the a2 and the inner surface of the peripheral wall portion 4b of the storage case 4 and breaking the seal.

[0032]

In the capacitive pressure sensor unit according to the present invention, an annular seal surrounded by the second insulating base of the pressure sensor element, the base of the connector body of the connector, and the peripheral wall of the storage case. A member housing space is formed, and the seal member is housed in the seal member housing space and brought into contact with the second insulating base, the base of the connector main body, and the peripheral wall of the housing case. In addition, the seal between the connector body and the storage case can be used as well, and the number of seal members used can be reduced. Also, even if a suddenly large pressure is applied to the pressure sensing surface by the fluid to be measured in the fluid chamber in a direction orthogonal to the pressure, the sealing member is arranged on the opposite side to the pressure sensing surface where the pressure acts, so that the pressure The seal can be prevented from being broken by the pressure acting on the sensing surface.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first example of an embodiment of a capacitance type pressure sensor unit according to the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a second example of the embodiment of the capacitance type pressure sensor unit according to the present invention.

FIG. 3 is a longitudinal sectional view of a conventional capacitance type pressure sensor unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first insulating substrate 1 a pressure sensing surface 2 second insulating substrate 2 a surface 2 b outer peripheral surface 3 pressure sensor element 4 storage case 4 a bottom wall 4 b peripheral wall 5 fluid inlet 6 gap 7 fluid chamber 8 backup ring 9 Seal member 10 Electronic circuit element 11 Flexible printed circuit board 12 Connector 13 Connector body (Connector housing) 13a Base 13a1 End surface 13a2 Outer peripheral surface 14 Support ring 15 Seal member 16 Seal member 17 Connector terminal 18, 19 Tapered surface 20 Seal member storage space 21 O Ring 22 Backup ring 23 Clearance

Claims (4)

[Claims] A first insulating substrate having an electrode on a front surface and a back surface serving as a pressure sensing surface; and an electrode facing the electrode of the first insulating substrate at a predetermined interval. A pressure sensor element including a second insulating base combined with a first insulating base; and a connector main body made of insulating resin arranged to be in contact with the second insulating base of the pressure sensor element. A bottom wall portion formed with a fluid inlet for introducing a fluid to be measured, and a peripheral wall portion having one end connected to the bottom wall portion, wherein the pressure sensing surface faces the bottom wall portion. And house the pressure sensor element so as not to form a large gap between the peripheral wall portion, house at least the base of the connector body,
Moreover, a storage case configured to form a fluid chamber into which the fluid to be measured enters between the pressure sensing surface of the pressure sensor element and the bottom wall portion, and the fluid in the fluid chamber leaks through the gap. A capacitive pressure sensor unit comprising a seal member for preventing the connector from coming out, wherein the second insulating base of the pressure sensor element, the base of the connector main body of the connector, and the housing. An annular seal member storage space surrounded by the peripheral wall portion of the case is formed, and the seal member is stored in the seal member storage space, and the second insulating base, the base portion of the connector main body, and the storage space. An electrostatic capacitance type pressure sensor unit comprising an O-ring contacting the peripheral wall of the case. 2. A first insulating substrate having an electrode on a front surface and a back surface serving as a pressure sensing surface, and an electrode on the rear surface facing the electrode of the first insulating substrate at a predetermined interval. A pressure sensor element comprising a second insulating substrate combined with the first insulating substrate; and a base arranged such that an end face of the base contacts the surface of the second insulating substrate of the pressure sensor element. A connector having a connector main body made of an insulating resin; a bottom wall formed with a fluid inlet for introducing a fluid to be measured under pressure; and a peripheral wall having one end connected to the bottom wall. The pressure sensor element is accommodated so as not to form a large gap between the bottom wall portion and the peripheral wall portion, the base portion of the connector main body is accommodated, and the end portion of the peripheral wall portion is provided. The base of the connector body by swaging A metal storage case configured to prevent slipping and to form a fluid chamber in which the fluid to be measured enters between the pressure sensing surface of the pressure sensor element and the bottom wall; And a seal member for preventing the fluid in the fluid chamber from leaking therethrough, wherein the base portion of the connector main body includes the end surface and the outer peripheral surface of the base portion. An annular tapered surface is formed between the tapered surface and the peripheral wall of the storage case, and an annular seal is formed between the tapered surface and the second insulating base of the pressure sensor element. A member housing space is formed, and the seal member is housed in the seal member housing space and comes into contact with the annular tapered surface, the second insulating base, and the inner surface of the peripheral wall portion of the housing case. Capacitive pressure sensor unit, characterized in that it consists of an O-ring. 3. An annular tapered surface is formed between the surface of the second insulating substrate of the pressure sensor element and the outer peripheral surface of the second insulating substrate, the diameter of the annular tapered surface decreasing toward the surface. The capacitance type pressure sensor unit according to claim 2, wherein: 4. In the sealing member storage space, the annular tapered surface formed at the base of the connector main body and the inner surface of the peripheral wall of the storage case are brought into contact with each other, and 3. A back-up ring for preventing the O-ring from entering into a gap formed between the outer peripheral surface of the base and the inner surface of the peripheral wall of the storage case. Or a capacitance type pressure sensor unit according to item 3.