JP2531924Y2 - Pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pressure sensor, and particularly to a seal structure.

[Prior Art] For example, a pressure sensor used for detecting pressure such as oil pressure includes a pressure introduction port, a diaphragm that deforms in accordance with pressure applied from the port, and a strain gauge that detects deformation of the diaphragm. ing.

By the way, in this type of pressure sensor, it is necessary to provide a sufficient seal so that the pressure or fluid introduced from the pressure introduction port does not leak to the electric circuit inside the sensor or the outside of the sensor.

Examples of a conventional pressure sensor are shown in FIGS. 3 and 4, respectively.

[Problem to be Solved by the Invention] The pressure sensor shown in FIG. 3 will be described. Reference numeral 51 denotes a casing, which has a pressure introduction port 51a. Reference numeral 52 denotes a diaphragm, and a deformed portion 52 formed in a thin portion at the center thereof.
a is provided. The deformed portion is provided with a strain gauge (not shown). Pressure inlet port of diaphragm 52
An annular groove 52b is formed on the wall surface on the 51a side.
An O-ring 53 is fitted to 52b. So in this example,
O-rings 53 seal the surfaces of the casing 51 and the diaphragm 52 that face each other.

When assembling the pressure sensor shown in FIG.
After fitting the 53 into the groove 52b of the diaphragm 52, the diaphragm 52 is assembled to the casing 51. However, O-ring
53 is relatively easily detached from the groove 52b.
When assembling the casing 2 to the casing 51, the O-ring 53 easily falls off from the diaphragm 52. Therefore, the O-ring 53 is
If the O-ring is dropped, the seal will be defective. In order to correct the drop of the O-ring, the O-ring must be disassembled again and assembled again.

The pressure sensor shown in FIG. 4 will be described. The casing of this pressure sensor is constituted by combining two members 61 and 64. The member 61 has a pressure introduction port 61a. Reference numeral 62 denotes a diaphragm, which has a deformed portion 62a formed in a thin portion at the center thereof. In this deformed part,
An unillustrated strain gauge is provided. A protrusion 61b is formed on the member 61 so as to face the deformed portion 62a of the diaphragm 62, and an annular groove 6 formed on the outer peripheral surface of the protrusion 61b is formed.
An O-ring 63 is fitted to 1c. That is, in this example, the shaft between the outer periphery of the projection 61b of the casing member and the inner peripheral wall of the diaphragm 62 is sealed.

The assembly of the pressure sensor of FIG. 4 is easier than that of FIG. However, the casing is divided into two members 61,6
Since it is configured by combining 4, the number of parts is large, and it is unavoidable to increase the size. If the casing is
If it is intended to be composed of one member like 51, the protrusion 61b
Since there is a portion corresponding to the member 64 on the outer periphery of the groove 61,
Processing of c becomes extremely difficult. Also, when the groove for fitting the O-ring is to be formed on the inner peripheral wall of the diaphragm 62, the processing of the groove is similarly difficult.

Further, a method of welding a casing having a pressure introduction port and a diaphragm over the entire circumference thereof is also conceivable, but in such a case, the following inconvenience occurs.

* Welding is relatively expensive.

* Materials for casing and diaphragm are limited to those that can be welded.

* Welding must be performed after the strain cage is attached to the diaphragm, and heat is generated during welding, resulting in deterioration of detection sensitivity and linearity.

An object of the present invention is to eliminate the various disadvantages described above.

[Means for Solving the Problems] The pressure sensor of the present invention has a pressure introducing port (11) formed therein, and a part of the pressure introducing port (11) is formed in a cylindrical projection (15). ), A casing member (10) having an outer cylindrical portion (13) formed in a cylindrical shape so as to cover the outside of the projection (15); and accepts a tip of the cylindrical projection (15). It has a circular groove (21) and a thin flexible portion (22) serving as the bottom of the groove substantially at the center thereof, and is arranged so as to support the flexible portion (22) and cover the periphery thereof. Thick cylindrical part (24)
Is a detection member (2) disposed in a space between the projection (15) of the casing member (10) and the outer cylindrical portion (13).
0); a corner portion of the detection member (20) where the inner peripheral surface of the circular groove (21) intersects with one end surface, that is, the circular groove (2
An annular groove (26) formed at the opening edge of 1); disposed in a space formed between the outer periphery of the projection (15) of the casing member (10) and the annular groove (26). An annular seal member (29); and a flexure detecting means (23) attached to the flexible portion (22) of the detection member (20). The inner diameter of the seal member (29) is (15), the inner diameter of the circular groove (21) is substantially the same as the outer diameter of the projection (15), and the height of the projection (15) is The cylindrical protrusion (15) is larger than both the thickness of the seal member (22) and the depth of the annular groove (26), and the center of the seal member (29) and the annular groove (26) It is characterized by penetrating into the circular groove (21).

In addition, in order to facilitate understanding, the reference numerals of the corresponding elements in the embodiments shown in the drawings and described later are added for reference in parentheses.

[Operation] According to the present invention, the space required for disposing the seal member such as the O-ring is an annular portion formed at the corner of the thick portion of the detection member where the inner peripheral wall and one end face intersect. And the outer periphery of the protrusion of the casing member. In the case where the detection member is a single member, the corner portion has nothing to cover the periphery thereof, so that processing for forming a groove in that portion can be easily performed. Further, the space for disposing the seal member is provided so as to be in contact with the outer periphery of the protrusion, and the protrusion is formed so as to protrude from the inner wall of the casing member. Therefore, the seal member is disposed on the outer periphery of the protrusion. If so, there is no danger of its position shifting in the radial direction.
Therefore, if the casing member and the detecting member are combined in a state where the seal member is fitted to the outer periphery of the projection, the assembly member such that the seal member deviates from the predetermined space and the sealing failure occurs does not occur. This greatly simplifies the assembly operation.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[Embodiment] FIG. 1 shows a longitudinal section of a type of pressure sensor embodying the present invention, and FIG. 2 shows an exploded state of a main part thereof. This pressure sensor will be described with reference to FIG. 1 and FIG.

The casing 10 includes a cylindrical connection portion 12 having a pressure introduction port 11 formed at the center thereof, and a relatively large-diameter cylindrical cover portion 13 covering the outer periphery of the pressure sensor. A cylindrical projection 15 protruding from one end face 14 of the casing is formed inside the cover 13, and the pressure introduction port 11
Is formed so as to penetrate both the connection portion 12 and the projection portion 15. A screw 12a is formed on the outer periphery of the connection portion 12. Reference numeral 16 denotes an O-ring for sealing.

The outer shape of the diaphragm 20 is substantially disk-shaped so that it can be fitted inside the cover portion 13 of the casing 10. The casing 10 is provided at the center of the diaphragm 20.
A circular groove 21 is formed so that the projection 15 can be inserted. The deformed portion 22 formed extremely thin by the groove 21 can bend in its thickness direction in response to an external force. A strain gauge 23 is mounted on one surface of the deformed portion 22. The strain gauge 23 is made of an amorphous metal, and includes four detectors (not shown). Each of the detectors receives a compressive or tensile stress with respect to the deformation of the deformable portion 22 in the thickness direction. Is detected as a change in resistance value. The four detectors are electrically connected to form a bridge circuit.

By combining the casing 10 and the diaphragm 20, the thicker peripheral portion 24 of the diaphragm 20
Is disposed in the space between the cover 13 and the projection 15 of the
15 enters the groove 21 of the diaphragm 20. In addition, an annular groove 26 is formed over the entire circumference at a circumferential corner at a position where the inner peripheral wall 24a of the peripheral portion 24 intersects with the one end face 25, and a step is formed on the inner peripheral wall 24a. Are formed.

Therefore, by combining the casing 10 and the diaphragm 20, an annular space surrounded by the outer peripheral wall (and the end face 14) of the projection 15 of the casing 10 and the groove 26 of the diaphragm 20 is formed. An O-ring 29 for sealing is arranged in the space.

When assembling this pressure sensor, first,
An O-ring 29 is fitted to the outside of the projection 15 of the above, and then the diaphragm 20 is mounted on the casing 10. In this case, O
Since the inner diameter of the ring 29 is equal to the outer diameter of the projection 15, there is no possibility that the O-ring 29 will be displaced in the radial direction when the diaphragm 20 is mounted on the casing 10, and therefore, the O-ring 29 It is reliably positioned in a predetermined space.
For this reason, there is no possibility that a defective seal will occur at the O-ring 29 due to an assembly error.

The diaphragm 20 is fixed to the casing 10 by the fixing member 30.
Fixed to The fixing member 30 is formed in an annular shape,
The outer diameter is equal to the inner diameter of the cover portion 13, and the inner diameter is slightly larger than the outer diameter of the small diameter portion 27 of the diaphragm 20. Also, the fixing member
A screw 31 is formed on the outer periphery of the screw 30 and is screwed with a screw 13a formed on the inner peripheral wall of the cover 13 of the casing. That is, after assembling the diaphragm 20 with the casing 10, if the fixing member 30 is screwed into the casing 10, the end surface 32 of the fixing member 30 will have a flange formed on the diaphragm 20.
Press the end face of 28 and fix it to the casing 10.

Since such a fixing method is used, the diaphragm
The pressing force is applied to the 20 relatively uniformly only in the thickness direction, and there is no need to apply a radial force that gives an abnormal stress to the deformed portion 22. Further, in this example, the large diameter portion of the diaphragm 20, that is, the outer diameter of the flange 28 is slightly smaller than the inner diameter of the cover portion 13 of the casing 10. Therefore, there is a space between the inner wall of the cover 13 and the peripheral wall of the flange 28.
33 are formed. For this reason, even if an external force in the radial direction is applied to the cover portion 13 of the casing and the cover portion 13 is bent, the force is not transmitted to the diaphragm 20.
Further, in this example, since the portion provided with the step by the flange 28 is pressed by the fixing member 30, the covering portion of the casing is provided.
Even when the fixing member 30 is deformed by an external force applied to 13, the influence of the fixing member 30 on the deformed portion 22 of the diaphragm 20 is smaller.

A terminal plate 35 is fixed to one end surface of the diaphragm 20,
Each electrode of the terminal plate is electrically connected to each terminal of the strain gauge 23 on the diaphragm 20. Note that an opening 36 is provided at the center of the terminal plate 35 so as not to hinder the deformation of the deformed portion 22 of the diaphragm 20. One end of the terminal plate 35 has a support 37
And a metal terminal 38 is provided at the other end. Although only one terminal is shown in the drawing, the terminal plate
35 has four terminals 38.

Reference numeral 40 denotes a hybrid IC, which includes an electric circuit for converting a change in the resistance value of the strain gauge 23 into a change in voltage. This hybrid IC 40 is fixed on the terminal plate 35,
And it is electrically connected to it. That is, hybrid IC
One end 40a of 40 is a projection 3 provided on the support portion 37 of the terminal plate.
7a, the other end 40b is soldered to the terminal 38, and is fixed by being sandwiched between the protrusion 37a and the terminal 38. Terminal 3
The protrusions 38a and 38b provided on 8 are connected to electric circuit terminals on the front and back surfaces of the hybrid IC 40, respectively. That is, the end portion 40b is fixed while being sandwiched between the front and back by the two protrusions 38a and 38b. Also, the end portion 40a has a projection 37a.
, But not fixed. protrusion
The height (dimension in the thickness direction) of 37a is larger than the thickness of the hybrid IC 40. Since the terminal 38 expands and contracts in accordance with the ambient temperature, the position of the end 40b of the hybrid IC 40 moves in the thickness direction with the change. However, since the other end 40a of the hybrid IC 40 is not fixed, the whole of the hybrid IC 40 moves in the thickness direction with the deformation of the terminal 38. For this reason, there is no possibility that stress acts on the connection portion (soldered portion) between the terminal 38 and the hybrid IC 40, and high reliability is obtained in the connection state of that portion. Note that even when the hybrid IC 40 moves in the thickness direction, its end 40
Since the height of the protrusion 37a that supports a has a margin, there is no risk that the end 40a of the hybrid IC 40 will fall off from that portion.

The connection between the hybrid IC 40 and the external circuit is made via a feedthrough capacitor 41. Although only one feedthrough capacitor 41 is shown in the drawing, three feedthrough capacitors are actually provided. One end 41a of a pin of each feedthrough capacitor is connected to a power supply terminal, an output terminal, and a ground terminal of the hybrid IC 40, respectively. Connect the lead wire 4 to the other end 41b of the pin.
8 is connected.

Three members 42,4 arranged on the right side of the hybrid IC 40
3 and 44 are provided for electrostatic shielding and for preventing intrusion of fluid from the outside. Each of the members 42 and 44 is a circular plate formed by pressing a plate-shaped metal by pressing, and 43 is an O-ring for sealing. The plates 42 and 44 have holes 42a and 44a, respectively, through which the support portion 41c of the feedthrough capacitor 41 passes.

The plate 42, the O-ring 43, and the plate 44 are inserted inside the cover 13 of the casing and fixed by swaging. Plates 42 and 44 are fixed with their central portions abutting each other. Therefore, the cross-sectional shape of the space where the O-ring 43 is disposed is the peripheral portion 42b of the plate 42, the slope portion 44b formed around the plate 44, and the inner wall 1 of the cover portion 13.
3b form a triangle. That is, plate 4
Triangular sealing is performed by the 2,44, O-ring 43 and the casing 10.

Reference numeral 45 denotes a resin cover, and a space inside the cover 45 is filled with an epoxy resin 46.

[Effects] As described above, according to the present invention, there is no fear that the member that seals between the casing and the diaphragm is displaced when the casing and the diaphragm are assembled, so that the occurrence of poor sealing is prevented, and the assembling is prevented. Work becomes easier. In addition, since the position of the groove for forming the space for disposing the seal member is not a difficult-to-process portion inside the part,
The shape processing of the part can be easily performed, and the cost can be reduced. Further, since welding is unnecessary, there is no change in the detection characteristics of the strain detector due to heat.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one type of pressure sensor embodying the present invention. FIG. 2 is an exploded sectional view showing a main part of FIG. 3 and 4 are cross-sectional views each showing an example of a conventional pressure sensor. 10: Casing (casing member) 11: Pressure introduction port, 12: Connection part 13: Cover part, 14: End face 15: Projection, 16: O-ring 20: Diaphragm (detection member) 21: Groove, 22: Deformation part 23 : Strain gauge (deflection detecting means) 24: Peripheral part, 25: End face 26: Groove (annular groove), 27: Small diameter part 28: Flange 29: O-ring (seal member) 30: Fixed member, 31: Screw 32: End face, 33: Space 35: Terminal plate, 36: Opening 37: Support, 38: Terminal 40: Hybrid IC 41: Through capacitor 42,44: Plate, 43: O-ring 48: Lead wire

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuyuki Hashimoto 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Minori Yamanaka 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki (72) Inventor Kaoru Ohashi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Toshio Yutani 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-63-16240 (JP, A) JP-A-63-113331 (JP, A) JP-A-60-56243 (JP, U) JP-A-63-57539 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. A pressure introducing port is formed, and a part of the pressure introducing port has a cylindrical projection formed therein, and is formed in a cylindrical shape so as to cover the outside of the projection. A casing member having an outer cylindrical portion; a circular groove for receiving the tip of the cylindrical protrusion, and a thin flexible portion which is a bottom of the groove substantially at a central portion thereof to support the flexible portion. A detecting member in which a cylindrical thick portion disposed so as to cover the periphery thereof is disposed in a space between the protrusion of the casing member and the outer cylindrical portion; A corner portion where the inner peripheral surface and one end surface intersect, that is, an annular groove formed at the opening edge of the circular groove; disposed in a space formed between the outer periphery of the protrusion of the casing member and the annular groove An annular seal member;
And a deflection detecting means mounted on a flexible portion of the detection member; wherein the inner diameter of the seal member is substantially the same as the outer diameter of the protrusion, and the inner diameter of the circular groove is the same as that of the protrusion. The height of the projection is substantially the same as the outer diameter, and the height of the projection is larger than both the thickness of the sealing member and the depth of the annular groove, and the cylindrical projection is located at the center of the sealing member and the annular groove. A pressure sensor that penetrates through the groove and enters the circular groove.