JPS6316240A - Pressure detector - Google Patents

Abstract

PURPOSE:To hold a housing airtight and to obtain a high-sensitivity output signal by forming part of a sensing body as a pressure receiving diaphragm and pressing the sensing body against the internal wall of the housing across on O ring. CONSTITUTION:A pressure lead path 21 penetrates the housing 2 in the center and its upper end is open in a recessed part 22 on the top surface of the housing 2. A groove 23 which surrounds the opening of the lead path 21 is formed in the bottom surface of the recessed part 22 and the O ring 5 is provided in the groove 23. The sensing body 1 is pressed against the ring 5 in the recessed part 22 with a pressure ring 5. The screw part on its outer peripheral surface of the ring 6 is engaged threadbly with the screw part 22a at the inner periphery of the recessed part 22. Further, the body 1 has the center part made thin opposite the lead path 21 to form the pressure receiving diaphragm 11. Then when hydraulic pressure is applied to the diaphragm 11 through the lead path 21, the diaphragm 11 deforms according to the pressure and strain gauges 31-34 vary in resistance value according to the deformation strain. This resistance value variation is led out as a pressure signal by a lead wire 75 through a signal processing circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure detector, and more particularly to a pressure detector that can accurately detect the pressure of high-pressure fluid and does not require the effort of processing and assembly.

[Conventional technology] A typical structure of a conventional pressure detector is shown in FIG.

The pressure sensor has a cylindrical housing 2, the housing 2
A threaded portion 2a is formed on the outer periphery of the lower half of the pressure chamber having a small diameter, and is screwed into a mounting hole provided in the wall of the pressure chamber to be measured using the threaded portion 2a. Inside the large diameter main body of the housing 2 is a sensing body 1 made of metal with a small coefficient of thermal expansion.
is the provision.

The sensing body 1- is a cylindrical body with an open top end and a pressure introduction path P inside the cylinder.The thick plate-like upper end portion is brought into contact with a stepped portion of the inner wall of the housing 2, and the cylindrical body is placed under the housing 2. It is inserted into the half and the lower end periphery is welded and fixed to the housing tip opening. The upper end of the sensing body 1- has a thin center wall as a pressure receiving diaphragm 11, and a metal strain gauge 3- is joined to the upper surface of the diaphragm 11.

The output signal of the strain gauge 3- is taken out via a lead wire 31 from a connector 4 tightly fitted into an opening at the upper end of the housing 2.

[Problems to be Solved by the Invention] In the pressure detector having the above structure, it is necessary to carefully weld the housing 2 and the sensing body 1' to ensure airtightness of the housing 2. There is a problem in that it requires precise processing and requires time and effort to manufacture and assemble.

Furthermore, since the metal strain gauge 3- has a low output sensitivity, there is a problem in that the signal processing circuit becomes complicated due to signal amplification and accompanying noise removal.

The present invention aims to solve these problems all at once, and is a pressure measurement system that reliably maintains the airtightness of the housing without requiring much effort in manufacturing and assembling, and that also provides a highly sensitive output signal. The purpose is to provide a detector.

[Means for solving the problem] In FIG. 1, a pressure introduction passage 21 that communicates between the pressure chamber and the inside of the housing 2 is provided through the tip of the housing 2, and an inner end opening of the pressure introduction passage 21 is provided. The sensing body 1 is provided to block this.

The sensing body 1 has a thin portion facing the inner end opening to form a pressure receiving diaphragm 11, and an O-ring 5 is provided on the periphery of the inner end opening to which the sensing body 1 is hermetically pressed. A semiconductor chip 3 on which a semiconductor strain gauge is formed is bonded to the inner surface of the pressure receiving diaphragm 11.

[Functions and Effects] The pressure detector having the above structure can be suitably used for high pressure measurement because the pressure receiving diaphragm 11 is a part of the sensing body 1 made of a strong material. Since the structure is such that the housing 2 is pressed into contact with the inner wall of the housing 2 through the housing 2, the airtightness of the housing 2 can be reliably maintained without requiring much effort in manufacturing and assembling.

Furthermore, since the semiconductor chip 3 on which the semiconductor strain gauge is formed is integrally bonded to the pressure receiving diaphragm 11, a highly sensitive and linear output signal can be obtained.

[Example] In FIG. 1, the detector housing 2 is a columnar body with different diameters, the lower half of the small diameter has a threaded portion 2a formed on the outer periphery, and the outer periphery of the upper half of the large diameter has a hexagonal surface. . A pressure introduction passage 21 passes through the center of the housing 2, and its upper end opens into a circular recess 22 on the upper surface of the housing 2. A circumferential groove 23 is formed on the bottom surface of the recess 22 so as to surround the opening of the pressure introduction path 21, and an O-ring 5 is disposed within the groove 23.

Inside the recess 22, Fe-N1-Go, which has a small coefficient of thermal expansion, is
A disc-shaped sensing body 1 made of a metal alloy is inserted, and the sensing body 1 is pressed against the O-ring 5 by a retaining ring 6 that abuts the outer periphery of the upper surface. The retainer ring 6 has a threaded portion on its outer circumferential surface screwed into a threaded portion 22a on the inner circumference of the recess 22. The sensing body 1 has a thin wall at the center facing the pressure introduction path 21, and serves as the pressure receiving diaphragm 11.

The semiconductor chip 3 is bonded to the upper surface of the pressure-receiving diaphragm 11 by a glass layer 71, as shown in FIG. The glass 1i71 is made of amorphous glass containing lead oxide as a main component, and the filler particle size is 2-0 μm on average and 20 μm or less at maximum. The thickness of the glass layer 71 is 20
The surface roughness of the sensing body 1 on which the glass layer 71 is formed is 0.5 μm to 3 μm.

The semiconductor chip 3 is made of a silicon single crystal plate, and as shown in FIG. 3, impurities such as boron (B) are doped at four locations on the chip to form semiconductor strain gauges 31, 32, 33, and 34. The strain gauges 31 and 33 are located directly above the center of the pressure receiving diaphragm 11, and the strain gauges 32 and 34 are located directly above the periphery of the pressure receiving diaphragm 11. These strain gauges 31 to 34 are connected to each other by electrode leads (not shown) formed on the chip 3 to form a full bridge circuit as shown in FIG. 4.

A terminal plate 72 (FIG. 2) is provided on the sensing pod 1 to surround the semiconductor chip 3, and the strain gauges 31 to 34 are connected to electrodes ( circuit). A signal processing circuit board 73 is disposed above the semiconductor chip 3, and the board 73 is supported on the terminal board 72 by lead pins 74, and the signal processing circuit is connected to the terminal board 72 via the lead pins 74. connected to the above electrode.

A cylindrical cover 24 is joined to the outer periphery of the upper surface of the housing 2, and a lead holder 81 is tightly fitted into the upper opening of the cover 24. A lead wire 75 extending from the signal processing circuit board 73 passes through the lead holder 81 and extends outside the detector. In the figure, 82 and 83 are sealing resins, and 84 is a sealing ring.

In the pressure detector having the above structure, when fluid pressure acts on the pressure receiving diaphragm 11 through the pressure introduction path 21, the diaphragm 11 deforms according to the pressure, and the resistance values of the strain gauges 31 to 34 change according to the deformation strain. . The change in resistance value is extracted as a pressure signal by a lead wire 75 via a signal processing circuit.

In the present invention, the pressure-receiving diaphragm 1] is made of a material with high strength, so it can follow high pressure without being damaged, and the semiconductor chip 3 on which the semiconductor strain gauges 31 to 34 are formed is integrated into the diaphragm 11. Since it is bonded to a high sensitivity and sharp output signal, it is possible to obtain a high sensitivity and sharp output signal.

In general, in the present invention, the sensing body 1 is pressed against the inner wall of the housing 2 via the O-ring 5 to maintain airtightness within the housing 2, so that manufacturing and assembly are easy. In particular, in this embodiment, by forming the sensing body 1 into a flat plate shape, the number of manufacturing steps can be significantly reduced.

When a groove 12 of a constant depth as shown in FIG. 5 is formed on the upper surface of the sensing pod 1 around the joint of the semiconductor chip 3,
It is possible to effectively prevent the strain generated when the sensing pod 1 is pressed into contact with the chip 3 from being transmitted to the chip 3.

FIG. 6 shows a further embodiment of the present invention. In the figure, the sensing body 1t is a stepped cylinder with different diameters, and the upper end opening is closed with a thin wall part to form a pressure receiving diaphragm 11, and a semiconductor chip 3 on which a semiconductor strain gauge is formed on the upper surface of the pressure receiving diaphragm 1. is the joint. The sensing pod 1 aligns its axis with the pressure introduction path 21 and tilts the lower half of the large diameter into the recess 22 of the housing 2.
An O-ring 5 is inserted between the opening edge of the sensing pod 1 and the opening edge of the pressure introduction hole 21 on the bottom surface of the recess 22.

A standing wall 25 for caulking is formed around the opening of the recess 22, and the standing wall 25 is bent onto the stepped surface of the sensing pod 1 as shown in the figure to suppress and fix it.

Such a structure also provides the same effects as those of the above embodiment, and further facilitates assembly by caulking.

In this case, in order to prevent distortion during caulking from spreading to the pressure receiving diaphragm 11, a circumferential groove]2 is formed on the sensing body surface between the caulking part and the pressure receiving diaphragm 11, as shown in FIG. 7 or 8. good.

[Brief explanation of drawings]

Fig. 1 is an overall sectional view of a pressure detector showing a first embodiment of the present invention, Fig. 2 is an enlarged sectional view of a sensing body attachment part, Fig. 3 is a plan view of a semiconductor chip, and Fig. 4 is a semiconductor chip. A connection diagram of a strain gauge, FIG. 5 is an enlarged cross-sectional view of a sensing body showing a second embodiment of the present invention, and FIG. 6 is an enlarged cross-sectional view of a sensing body mounting portion showing a third embodiment of the present invention. , 7 and 8 are enlarged sectional views of sensing pods showing fourth and fifth embodiments of the present invention, respectively, and FIG. 9 is an overall sectional view of a pressure detector showing a conventional example. 1... Sensing pod 11... Pressure receiving diaphragm 2... Housing 21... Pressure introduction path 3... Semiconductor chip 31.32. 33.34...Semiconductor strain gauge 5
・・・・・・01Nong Fig. 1 v, 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7, 8゜ Fig. 9

Claims (2)

[Claims] (1) The housing, which is fixed to the pressure chamber wall and has its tip facing into the pressure chamber, is provided with a pressure introduction path that communicates between the pressure chamber and the inside of the housing, and an inner end of the pressure introduction path. A sensing body made of a strong material is provided in the opening so as to close it, and the sensing body has a thin portion facing the inner end opening to form a pressure receiving diaphragm, and an O-ring is provided around the inner end opening. A pressure detector characterized in that the sensing body is brought into airtight pressure contact therewith, and a semiconductor chip on which a semiconductor strain gauge is formed is bonded to the inner surface of the pressure receiving diaphragm. (2) The pressure detector according to claim 1, wherein the sensing body is made of a Fe-Ni-Co alloy.