JP2002013994A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately inspect the air-tightness of a seal part in a pressure sensor with the structure that a boundary between the opening part side of a metal stem having a pressure detecting diaphragm and the pressure lead-in passage side of a metal housing is air-tightly bonded to each other by using a metal touch seal. SOLUTION: A stepped cylindrical screw member 20 and a housing 30 are connected to each other by screwing, and a step part 13 of a stepped hollow cylindrical metal stem 10 is pushed by the screw member 20 inside the screw member 20 so as to seal a boundary part K1 between the opening part 12 side of the metal stem 10 and the pressure lead-in passage 32 side of the housing 30. With the structure that a surface of the step part 13 of the metal stem 10 is formed with a groove 14, a first space 101 positioned on the diaphragm 11 side of the metal stem 10 through the screw member 20 and a second space 102 positioned on the opening part 12 side of the metal stem 10 are communicated with each other through the groove 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal stem having a detecting portion for detecting pressure and a metal housing which are hermetically joined by a metal touch seal, and holding the metal stem at a portion other than the hermetically joined portion. In particular, the present invention relates to prevention of an inspection error in an airtightness inspection of an airtight joint.

[0002]

2. Description of the Related Art FIG. 3 shows a general sectional structure of a conventional pressure sensor of this type. Reference numeral 30 denotes a metal housing, in which a pressure introducing passage 32 for introducing pressure from outside is formed. Reference numeral 10 denotes a metal stem, which has a diaphragm (detection unit) 11 for detecting pressure at one end and an opening 1 for introducing pressure introduced into the pressure introducing passage 32 to the diaphragm 11 at the other end.
2 has a hollow stepped cylindrical shape.

A stepped cylindrical screw member (holding member) 20 for holding the metal stem 10 in the housing 30 is interposed between the metal stem 10 and the housing 30. The screw member 20 is screw-coupled to the housing 30 and supported by the housing 30, and has an inner peripheral surface thereof abutting against a step 13 formed at an intermediate portion in the axial direction on the outer peripheral surface of the metal stem 10. In this state, the metal stem 10 is pressed against the housing 30.

Thus, the opening 1 of the metal stem 10 is
The second side and the pressure introducing passage 32 side of the housing 30 are in contact with each other to seal the boundary K1. Further, the outer peripheral space of the metal stem 10 is connected to one end side of the metal stem 10 via the screw member 20 (the diaphragm 11 side). ) And the other end of the metal stem 10 (the opening 12 side).
And a space (second space) 102 located at

[0005] As described above, the metal stem 10 and the housing 30 are brought into contact with each other by metal, and by applying an axial force by means of screw connection or the like, a surface pressure higher than the surface pressure required for sealing is generated on the contact surface. , That is, hermetically bonded by a metal touch seal.

[0006]

By the way, in the above-mentioned metal touch seal type pressure sensor, in order to reliably guarantee the sealing property (airtightness) of the boundary portion K1,
It is necessary to perform an airtightness inspection (leakage inspection) of the boundary portion K1. In this inspection, for example, an inspection device such as a He leak detector is used, and pressure is introduced from the pressure introduction passage 32 to the work in a state where the metal stem 10 is assembled to the housing 30 via the screw member 20.

However, in the conventional structure, in addition to the boundary portion K1, the contact portion K2 between the screw member 20 and the outer peripheral surface (the step portion 13) of the metal stem 10 and the screw member 20 and the housing 30 are connected. Since a load is also applied to the screw coupling portion K3, the second space 102 is partitioned from the first space 101 with a certain degree of airtightness. Therefore, even if there is a leak at the boundary K1,
Leakage from the second space 102 to the first space 101 is suppressed, and there is a possibility that it is determined that there is no abnormality in the sealing performance of the boundary portion K1.

In view of the above-mentioned problems, the present invention can accurately inspect the airtightness of the seal between the opening side of the metal stem and the pressure introducing passage side of the housing in the metal touch seal type pressure sensor. The purpose is to be.

[0009]

To achieve the above object, according to the first aspect of the present invention, a housing (30) having a pressure introducing passage (32) for introducing pressure from outside.
And a hollow cylindrical metal stem having a detection section (11) for detecting pressure on one end side and an opening (12) for guiding pressure introduced into the pressure introduction passage to the detection section on the other end side. (1
0) and a holding member (20) interposed between the metal stem and the housing and holding the metal stem in the housing, wherein the holding member is provided at an intermediate portion (13) in the axial direction on the outer peripheral surface of the metal stem. By pressing the metal stem against the housing in the abutting state, the boundary (K1) between the opening side of the metal stem and the pressure introduction passage side of the housing is sealed, and the space around the metal stem is held. The first space (10) located on one end side of the metal stem via the member
1) and a second space (10) located on the other end side of the metal stem.
2) In the pressure sensor sectioned into (1) and (2), a communication path that connects the first space and the second space to at least one of the surface of the outer peripheral surface of the metal stem that contacts the holding member and at least one of the holding members. 14) is formed.

[0010] According to the present invention, a communication path for communicating the first space and the second space is formed on a surface of the outer peripheral surface of the metal stem that contacts the holding member and at least one of the holding members. Therefore, the airtightness between the first space and the second space, which has caused an inspection error in the conventional structure, is eliminated. Therefore, the airtightness inspection of the seal portion between the opening side of the metal stem and the pressure introduction passage side of the housing can be accurately performed.

Here, as in the second aspect of the present invention, the communication passage has a surface in contact with the holding member (20) on the outer peripheral surface of the metal stem (10) and a metal stem in the holding member. It may be constituted by a groove (14) formed on at least one of the surfaces.

Incidentally, the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows an overall sectional configuration of a pressure sensor 100 according to an embodiment of the present invention. This pressure sensor 1
Reference numeral 00 denotes a fuel pipe (not shown) in a fuel injection system (for example, a common rail) of an automobile, which detects the pressure of fuel as a pressure medium in the fuel pipe.

The pressure sensor 100 of the present embodiment is
The metal stem 10 and the screw member 20 shown in FIG. 3 are partially modified, and the same parts as those in FIG. 3 are denoted by the same reference numerals in FIG. Also, FIG.
It is a perspective view which expands and shows the metal stem 10 in FIG.

The metal stem 10 is fixed to the housing 30 by a screw member (holding member according to the present invention) 20, has a thin diaphragm 11 as a closing part at one end of the shaft, and the other end of the shaft. It has a stepped hollow cylindrical shape with an opening 12 on the side. Further, a step 13 is formed at an intermediate portion of the outer peripheral surface of the metal stem 10 in the axial direction, and the other end (opening 12 side) of the metal stem 10 is connected to one end through the step 13. The outer diameter is larger than (diaphragm 11 side).

The diaphragm 11 of the metal stem 10 is configured as a detecting unit for detecting pressure, and a sensor chip made of single crystal Si (silicon) is provided on the outer surface of the diaphragm 11 as shown in FIG. 40 are joined by low melting point glass or the like. This sensor chip 40
Functions as a strain gauge for detecting a strain generated when the diaphragm 11 is deformed by the pressure introduced into the metal stem 10 from the opening 12.

The material of the metal stem 10 is required to have a high strength because it is subjected to an ultra-high pressure, and to have a low thermal expansion coefficient in order to join the sensor chip 40 made of Si with glass or the like. Include Fe, Ni, C
o or Fe or Ni as the main component, and T
A material to which i, Nb, Al or Ti, Nb is added is selected, and can be formed by pressing, cutting, cold forging, or the like.

The housing 30 is directly mounted on the fuel pipe as an object to be mounted, and has a mounting screw 31 formed on an outer peripheral surface thereof. Also, housing 3
A pressure introducing passage 32 communicating with the opening 12 of the metal stem 10 is formed in the inside of the metal stem 10.

The pressure introducing passage 32 is provided in the housing 30
Is connected to the inside of the fuel pipe while being attached to the fuel pipe, so that the pressure in the fuel pipe is introduced. Then, the pressure introduced into the pressure introduction passage 32 is introduced from the opening 12 into the metal stem 10,
It is guided to the inner side of the diaphragm 11.

A screw member (screw) 20 is interposed between the metal stem 10 and the housing 30 on the outer peripheral side surface of the cylindrical metal stem 10, and connects the metal stem 10 to the housing 3.
It functions as a holding member for holding at zero. Screw member 20
Has a stepped cylindrical shape that covers the outer periphery of the metal stem 10, and a male screw portion 21 is formed on the outer peripheral surface thereof.

On the other hand, the male screw portion 2 in the housing 30
A female screw portion 33 having a shape corresponding to the male screw portion 21 is formed in a portion corresponding to 1. The screw member 20 is fixed to the housing 30 by the screw connection of the male screw portion 21 and the female screw portion 33, and the inner peripheral surface of the screw member 20 is connected to the step 13 formed on the outer peripheral surface of the metal stem 10. It will be in contact. FIG. 2 shows this contact area by hatching.

In this state, since the pressing force from the screw member 20 is applied to the step portion 13, the metal stem 10 is pressed and fixed to the housing 30. Then, by this pressing force, the opening 12 side of the metal stem 10 and the pressure introduction passage 32 side of the housing 30 come into contact with each other to form a boundary portion (communication portion between the opening 12 and the pressure introduction passage 32) K1. This boundary portion K1 is sealed.

Here, the required quality of the housing 30 includes corrosion resistance from the pressure medium and the actual vehicle environment, and a screw strength for maintaining an axial force for generating a high sealing surface pressure at the boundary K1. Can be Therefore, the material of the housing 30 may be a high-strength carbon steel plated with Zn to increase the corrosion resistance, XM7 having corrosion resistance,
SUS430, SUS304, SUS630 and the like can be adopted.

The screw member 20 is required to have high strength in order to fix the metal stem 10 to the housing 30 and maintain an axial force for generating a high sealing surface pressure. The housing 3 is stored in the package
Unlike 0, no corrosion resistance is required, and carbon steel or the like can be used.

As described above, in the pressure sensor 100, the metal stem 10 and the housing 30 are hermetically joined by the metal touch seal, and the screw is formed at a portion other than the boundary portion (hermetically joined portion) K1 where the metal stem is joined. The metal stem 10 is held by the member 20.

The space around the metal stem 10 is
It is divided into a space (first space) 101 located on the diaphragm 11 side and a space (second space) 102 located on the opening 12 side via the screw member 20. FIG.
As shown in FIG. 1, the first space 101 is a gap between the outer peripheral surface of the small diameter portion of the metal stem 10 and the inner peripheral surface of the screw member 20, and the second space 102 is formed between the outer peripheral surface of the large diameter portion of the metal stem 10. This is a space surrounded by the lower end of the screw member 20 and the housing 30.

Here, in the present embodiment, the first space 101 and the second space 102 are not partitioned in an air-tight manner, and the first space 101 and the second space 102 are separated from the screw member 20 on the outer peripheral surface of the metal stem 10. The contact surface (that is, step 1
3) In addition, at least one of the screw members 20 is provided with a communication path that connects the first space 101 and the second space 102, so that the screw member 20 has a unique configuration in which the communication is established.

In the present embodiment, as shown in FIGS. 1 and 2, a groove (slit) 14 as a communication passage extends in the axial direction of the metal stem 10 on the surface of the step portion 13 of the metal stem 10. Is formed. Therefore, even if the inner peripheral surface of the screw member 20 and the step portion 13 come into contact with each other, this groove 1
The communication state between the first space 101 and the second space 102 is ensured via the fourth space 101.

Further, since the groove 14 only partially reduces the contact area between the step portion 13 and the screw member 20, the load on the metal stem 10 by the screw member 20 can be applied without any problem. Also, the groove 14 may be provided at a plurality of locations as long as it can be assembled.

Referring to FIG. 1, the general description of pressure sensor 100 will be continued. Reference numeral 50 denotes a ceramic substrate.
0 is an amplifier IC that amplifies the output of the sensor chip 40
The chip 52 and the characteristic adjustment IC chip 52 are fixed with an adhesive, and the IC chip 52 is connected to a conductor (wiring portion) of the ceramic substrate 50 by a thin aluminum wire 54 formed by wire bonding.
Further, pins 56 for electrically connecting to the connector terminals 60 are joined to the conductors of the ceramic substrate 50 by silver solder.

The connector terminal 60 is connected to the terminal 6
Reference numeral 2 denotes an assembly formed by insert molding the resin 64. The terminal 62 and the pin 56 of the ceramic substrate 50 are joined by laser welding. The connector terminal 60 is fixed and held to the connector case 70 by an adhesive 66, and the terminal 62 can be electrically connected to an ECU or the like of a vehicle via a wiring member.

The connector case 70 forms the outer shape of the connector terminal 60 and forms a package integrally with the housing 30 assembled via an O-ring 80. The sensor chip 40, various ICs,
It protects the electrical connection from moisture and mechanical external force. The material of the connector case 70 is P, which is highly hydrolyzable.
PS (polyphenylene sulfide) or the like can be employed.

The assembling method of the pressure sensor 100 having such a configuration is performed as follows. First, the screw member 20 and the metal stem 10 (the sensor chip 40 is joined)
The housing 30 is approached from above the integrated product, the screw member 20 and the housing 30 are relatively rotated, and the male screw portion 21 and the female screw portion 33 are screwed. Connect the metal stem 10 to the housing 3
Fix to 0.

Next, the ceramic substrate 50 on which the chips 52 and the pins 56 are mounted is bonded to the screw member 20 with an adhesive. At this time, although not shown in detail, the sensor chip 4
0 and a conductor (wiring portion) of the ceramic substrate 50 are electrically connected by wire bonding.

Next, the connector terminal 60 and the pin 56
Are joined by laser welding (YAG laser welding or the like).
Then, the connector case 70 is attached to the groove of the housing 30 via the O-ring 80, and the connector case 70 and the housing 30 are fixed by caulking the groove. Thus, the pressure sensor 100 shown in FIG. 1 is completed.

The pressure sensor 100 includes the housing 3
By directly connecting and attaching the No. 0 screw 31 to the screw portion formed on the fuel pipe (not shown), the fuel pipe is connected and fixed.

When the fuel pressure (pressure medium) in the fuel pipe is introduced from the opening 12 of the metal stem 10 into the interior (hollow portion) of the metal stem 10 through the pressure introduction passage 32, the pressure causes The diaphragm 11 is deformed, the deformation is converted into an electric signal by the sensor chip 40, and this signal is processed by the ceramic substrate 50 or the like constituting a processing circuit portion of the sensor to detect pressure. And
The fuel injection control is performed by the ECU or the like based on the detected pressure (fuel pressure).

In the present embodiment, an airtightness inspection (leakage inspection) of the boundary portion K1 is performed in the assembling step in order to ensure the sealing performance (airtightness) of the boundary portion K1. For this inspection, for example, using an inspection device such as a He leak detector, the screw member 2 is attached to the housing 30.
For a work in which the metal stem 10 is assembled through the pressure inlet passage 32, an inspection gas (for example, He)
Gas, etc.) as pressure medium to introduce pressure.

At this time, in the pressure sensor 100,
Since the first space 101 and the second space 102 are communicated with each other by the groove (communication passage) 14, the first space 101 and the second space 102 which have caused an inspection error in the conventional structure. The airtightness between them is lost.

Therefore, if there is no leak at the boundary portion K1, it can be determined that the sealing property is normal. If there is a leak at the boundary portion K1, the second portion on the boundary portion K1 side can be determined.
Since the test gas leaks from the space 102 through the groove 14 to the first space 101 (that is, into the outside air), it is possible to reliably detect an abnormality in the sealing property of the boundary portion K1.

Therefore, according to the present embodiment, the opening 1 of the metal stem 10 having the diaphragm 11 for detecting pressure is provided.
In the pressure sensor 100 in which the seal portion between the second side and the pressure introducing passage 32 side of the metal housing 30, that is, the boundary portion K1 is hermetically joined by a metal touch seal, the airtightness inspection of the boundary portion K1 is accurately performed. It can be carried out.

The groove 14 may be formed not on the surface of the step portion 13 but on the inner peripheral surface of the screw member (holding member) 20 which is in contact with the step portion 13, or the step portion 13 and the screw member 20 may be formed.
May be formed on the surfaces of both parts 13 and 20. Further, from the first space 101 side to the second space 102
A hole that penetrates through the inside of the screw member 20 may be formed on the side, and this through-hole may be used as the communication passage of the present invention. In addition, other than the groove 14, for example, the communication path may be a groove having a planar concave shape with an increased groove width.

Further, as the detecting portion provided on the metal stem, other than the diaphragm, any type can be used as long as it can output a signal based on pressure, such as a diaphragm type chip made of a semiconductor, a piezoelectric element, a strain gauge, and the like. Also,
The holding member may be anything other than screw connection as long as it can form a sealed hermetic joint by pressing the metal stem by contacting the middle part of the metal stem in the axial direction.

The present invention is, of course, applicable to various pressure sensors other than those for detecting the fuel pressure of the fuel injection system of an automobile.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a pressure sensor according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a metal stem in FIG.

FIG. 3 is a cross-sectional configuration diagram of a conventional general pressure sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Metal stem, 11 ... Diaphragm, 12 ... Opening of metal stem, 13 ... Step, 14 ... Groove, 20 ... Screw member, 30 ... Housing, 32 ... Pressure introduction passage, 101 ...
First space, 102: Second space, K1: Boundary portion between the opening side of the metal stem and the pressure introduction passage side of the housing.

Claims (2)

[Claims] 1. A housing (30) having a pressure introducing passage (32) for introducing pressure from the outside, a detecting section (11) for detecting pressure on one end side, and the pressure introducing section on the other end side. A hollow cylindrical metal stem (10) having an opening (12) for guiding the pressure introduced into the passage to the detection unit; and a metal stem (10) interposed between the metal stem and the housing. Holding member (2
0), and the opening of the metal stem is pressed by pressing the metal stem against the housing in a state where the holding member is in contact with the axial middle part (13) on the outer peripheral surface of the metal stem. A boundary portion (K1) between the portion side and the pressure introduction passage side of the housing is sealed, and a space around the metal stem is located at one end side of the metal stem via the holding member. And a second space located at the other end of the metal stem, at least one of a surface of the outer peripheral surface of the metal stem that comes into contact with the holding member, and the holding member. Has a communication passage (1) communicating the first space and the second space.
4) A pressure sensor, wherein the pressure sensor is formed. 2. The communication passage according to claim 1, wherein the communication passage includes the metal stem.
A surface in contact with the holding member (20) on the outer peripheral surface of
2. The pressure sensor according to claim 1, wherein the pressure sensor is constituted by a groove formed on at least one of the surfaces of the holding member that contacts the metal stem. 3.