JP7308522B2 - pressure sensor - Google Patents

Description

The present invention relates to pressure sensors.

A liquid-sealed pressure sensor that houses a semiconductor-type pressure sensing device in a pressure-receiving chamber partitioned by a diaphragm and filled with oil is installed in freezer/refrigerators and air conditioners to detect refrigerant pressure, and is also used in industrial equipment. installed and used to detect various fluid pressures.

The semiconductor type pressure detection device is arranged in the pressure receiving chamber and has a function of converting the pressure change in the pressure receiving space into an electric signal by means of the pressure detecting element and outputting the electric signal to the outside.

A diaphragm placed in the pressure receiving space is a flexible metal plate. Therefore, if a potential difference occurs between the pressure sensing element and the diaphragm of the semiconductor type pressure sensing device and the enclosed oil is charged with static electricity, the pressure sensing element or its output signal may malfunction. A potential difference between the pressure sensing element and the diaphragm can be caused, for example, by noise transmitted from the piping system to which the pressure sensor is attached.

On the other hand, Patent Literature 1 discloses a pressure sensor in which a base for mounting a semiconductor type pressure detection device is formed of a ceramic material. According to the pressure sensor of Patent Literature 1, since the semiconductor type pressure detection device is attached to the base made of ceramics, the insulation effect is exhibited, so that the influence of noise such as high frequency transmitted from the piping system can be effectively suppressed. .

JP 2017-146136 A

According to the pressure sensor disclosed in Patent Document 1, effective noise suppression can be achieved by forming the base from a ceramic material. There's a problem. In particular, since the base and the diaphragm cannot be directly welded, it is necessary to interpose a metal ring member therebetween, which further increases the part cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure sensor capable of suppressing the influence of noise while suppressing costs.

In order to achieve the above object, the pressure sensor of the present invention
a diaphragm that receives fluid pressure;
a base forming a pressure-receiving space filled with an insulating medium between itself and the diaphragm;
a pressure detection device disposed in the pressure receiving space for detecting the pressure transmitted to the insulating medium and converting it into an electrical pressure signal;
a plurality of terminal pins disposed through the base and electrically connected to the pressure detection device within the pressure receiving space, the pressure sensor comprising:
The base has a metal annular portion fixed to the diaphragm, and a ceramic center portion made of an insulating material disposed inside the annular portion,
The pressure detection device is arranged in the central portion,
The plurality of terminal pins are arranged to pass through the through-hole of the annular portion while being insulated and sealed by a hermetic seal .

According to the present invention, it is possible to provide a pressure sensor capable of suppressing the influence of noise while suppressing costs.

FIG. 1 is a longitudinal sectional view showing a pressure sensor according to a first embodiment; FIG. FIG. 2 is a longitudinal sectional view of the pressure detection unit according to the first embodiment; FIG. 3 is a top view of the pressure detection unit. 4 is a bottom view of a cross section of the pressure detection unit taken along line AA of FIG. 2. FIG. FIG. 5 is a longitudinal sectional view showing a pressure sensor according to a second embodiment;

(First embodiment)
Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a pressure sensor 1 according to the first embodiment. FIG. 2 is a longitudinal sectional view of the pressure detection unit 2 according to the first embodiment. FIG. 3 is a top view of the pressure detection unit 2. FIG. FIG. 4 is a bottom view of a cross section of the pressure detection unit 2 taken along line AA of FIG.

As shown in FIG. 1, the pressure sensor 1 includes a large cylindrical portion 10a having a circular cross section, for example, and a small cylindrical portion 10b having an annular, oval, or elliptical cross section, which are coaxially arranged. , and a resin-made cover 10 having a shape in which the respective ends are formed via a stepped portion 10c. A pressure detection unit 2 is attached inside the large cylindrical portion 10 a of the cover 10 .

The pressure detection unit 2 includes a dish-shaped mounting member 30 that supports a connection nut 20 to which a fluid inflow pipe (piping) (not shown) is screwed and connected, a dish-shaped base 40 that faces the mounting member 30, and a mounting It has a metal diaphragm 50 whose outer circumference is sandwiched between the member 30 and the base 40 . The mounting member 30 and diaphragm 50 can be made of, for example, a stainless alloy.

As shown in FIG. 2, the base 40 includes an annular portion 41 made of a conductive metal material such as SUS (stainless alloy), and a disc-shaped mount member (central portion) 42 joined to the inside of the annular portion 41. have The mount member 42 is made of an inorganic material such as ceramics or glass, or a highly heat-resistant insulating material such as polyamide, polyimide, polyethylene terephthalate (PET), or PPS. If the mount member 42 is made of ceramics, it is fixed to the annular portion 41 by brazing or adhesion, and if it is made of glass, it is fixed to the annular portion 41 by a hermetic seal. When the mount member 42 is made of resin such as polyamide, it is fixed to the annular portion 41 over the entire circumference with an adhesive. This prevents leakage of the insulating medium from the pressure receiving space 52 .

A concave portion 42a having a rectangular shape in bottom view is formed in the center of the surface of the mount member 42 on the diaphragm 50 side. A conductive layer 42b is formed on the bottom surface, side surfaces and periphery of the recess 42a. The material of the conductive layer 42b is typically gold, silver, copper, aluminum, nickel, or the like, but a high melting point material such as tungsten or molybdenum can also be used in order to obtain high voltage durability.

The attachment member 30, the annular portion 41 of the base 40, and the outer peripheral portion of the diaphragm 50 are integrated by a welded portion W formed by circumferential welding.

A cylindrical portion 20a is formed at the upper end of the connection nut 20 so as to protrude therefrom. On the other hand, a circular hole 30a is formed in the center of the mounting member 30. As shown in FIG. After the cylindrical portion 20a and the mounting member 30 are fitted together, they are joined by means such as brazing.

A through passage 20b is formed inside the cylindrical portion 20a, and the inside of the mounting member 30 and the inside of the connection nut 20 communicate with each other via the through passage 20b.

1 and 2, a pressure receiving space 52 defined by the base 40 and the diaphragm 50 is filled with an insulating liquid medium such as oil. After the liquid medium is filled into the pressure receiving space through the opening 40a (FIG. 4) formed in the annular portion 41 of the base 40, a metal ball 43 is welded to the base 40 to seal it. is fixed with

A semiconductor pressure detection device 60 is arranged in the recess 42 a of the base 40 . The pressure detection device 60 comprises a glass base 62 and a pressure detection element (semiconductor chip) 64 attached to the surface thereof. The pedestal 62 is fixed to the bottom surface of the recess 42a using an adhesive. A gap is provided between the pressure detection element 64 and the conductive layer 42b.

The surface of the pressure detection device 60 on the side of the diaphragm 50 is positioned within the recess 42a so as to be further away from the diaphragm 50 than the surface of the mount member 42 around the recess 42a. However, the surface of the pressure detection device 60 may be flush with the peripheral surface of the recess 42a.

In FIG. 4, the pressure sensing element 64 has eight bonding pads (electrodes) near its periphery. Three of the bonding pads are a sensor input power supply pad 64a, a ground pad 64b and a sensor output pad 64c, and the remaining five are signal conditioning pads 64d. However, the number of bonding pads is not limited to eight. In this embodiment, the sensor input power supply pad 64a is maintained at 5V, the ground pad 64b is maintained at 0V, and the voltage of the sensor output pad 64c is between 0V and 5V (preferably 0.5V) depending on the detected pressure. 4.5 V or less). Also, the arrangement of the bonding pads is not limited to the above.

A plurality of (eight in this example) terminal pins 70 and 72 are arranged around the semiconductor type pressure detection device 60 so as to pass through the base 40 . The terminal pins 70 and 72 are insulated and sealed by a hermetic seal 74 with respect to the through holes of the base 40 through which they are inserted.

One of the plurality of terminal pins is terminal pin 70 for ground. The seven terminal pins 72 other than those for grounding are connected to the wiring layer terminals of the relay board 90 shown in FIG. The upper end of one ground terminal pin 70 is connected to the ground of the wiring layer of the relay board 90 shown in FIG.

In FIG. 1, a lead wire 94 connected to a relay board 90 via a connector 92 is connected to an electric circuit (not shown) provided in a control panel of a freezer/refrigerator, an air conditioner, or the like in which the pressure sensor 1 is installed. be done. From such an electric circuit, a power supply voltage can be applied to the pressure detection element 64 via the lead wire 94 and the terminal pins 70 and 72, and a signal for pressure detection can be output.

In FIG. 4, the sensor input power supply pad 64a, the sensor output pad 64c, the signal adjustment pad 64d other than the ground pad 64b, and the terminal pin 72 in the semiconductor type pressure detection device 60 are connected by bonding wires 80. ) is done. Further, in this embodiment, the ground pad 64b is connected (wired) to the conductive layer 42b of the mount member 42 via the bonding wire 81. As shown in FIG. Also, the terminal pin 70 and the conductive layer 42b are connected (connected) via a bonding wire 82. As shown in FIG.

When assembling the pressure sensor 1, in FIG. 1, the annular portion 41 of the base 40 of the pressure detection unit 2 is arranged so as to abut against the stepped portion 10d formed inside the large cylindrical portion 10a of the cover 10. As shown in FIG. After that, the resin P is filled inside the cover 10 from the lower end side of the large cylindrical portion 10a and the upper end side of the small cylindrical portion 10b (the side from which the lead wire 94 is led out), and is solidified. The electrical structure of the pressure detection unit 2 is thereby fixed in the cover 10 in a hermetically sealed manner.

The pressure detection device 60 operates by receiving power from an external electric circuit via a terminal pin 72 for input power. When the fluid is introduced into the connection nut 20 and enters the fluid introduction chamber 32 inside the mounting member 30 , the pressure causes the diaphragm 50 to elastically deform and pressurize the insulating medium in the pressure receiving space 52 . The pressure detection element 64 detects this pressure variation, converts it into an electric signal, and outputs the electric signal, that is, a signal for pressure detection to the outside through the terminal pin 72 . An external electric circuit to which such a signal for pressure detection is input can accurately detect the pressure of the fluid introduced into the connection nut 20 based thereon.

According to this embodiment, the pressure detection device 60 is arranged on the mount member 42 made of an insulating material, so insulation from the annular portion 41 of the base 40 is ensured. Therefore, even if noise such as high frequency is transmitted from an external pipe to the annular portion 41 of the base 40 through the connection nut 20, such noise can be effectively blocked.

In addition, since the pressure detection device 60 is arranged inside the recess 42a, the distance between the pressure detection device 60 and the diaphragm 50 can be increased. In particular, by arranging the surface of the pressure detection device 60 in the recess 42a, it is possible to further distance it from the diaphragm 50, so even if the diaphragm 50 is electrified, the pressure detection device 60 can be suppressed from being affected.

Further, by providing the conductive layer 42b around the pressure detecting device 60, the electric charges around the pressure detecting device 60 or the electric charges charged in the liquid medium filled in the pressure receiving space 52 are transmitted through the conductive layer 42b. The charge is eliminated, thereby preventing malfunction caused by charging of the pressure detection device 60 .

(Second embodiment)
FIG. 5 is a longitudinal sectional view showing a pressure sensor 1A according to the second embodiment. In this embodiment, the shape of the mount member 42A on the base 40A of the pressure detection unit 2A is different from that in the above-described embodiment. More specifically, the depth of the recess 42Aa is shallower than in the above-described embodiment. On the other hand, since the pressure detection device 60 has the same shape, by fixing the pressure detection device 60 to the recess 42Aa, the surface of the pressure detection device 60 on the side of the diaphragm 50 is closer to the diaphragm 50 than the peripheral surface of the recess 42Aa. It will be done.

On the other hand, a circular insulating layer 51 is fixed to the pressure receiving space 52 side surface of the central flat portion of the diaphragm 50 so as to face the pressure detecting device 60 . The insulating layer 51 is, for example, a polyimide film, and is preferably adhered to the central flat portion of the diaphragm 50 . The insulating layer 51 has a higher dielectric constant than the insulating medium. Since other configurations are the same as those of the above-described embodiment, they are denoted by the same reference numerals and will not be described repeatedly.

According to this embodiment, the surface of the pressure detection device 60 on the side of the diaphragm 50 protrudes toward the diaphragm 50 from the peripheral surface of the recess 42Aa. However, since the insulating layer 51 is provided on the surface of the diaphragm 50 facing the pressure detecting device 60, the insulating medium is easily charged to the insulating layer 51 during noise transmission, thereby suppressing charging of the pressure detecting device 60. can.

It should be noted that the present invention is not limited to the above-described embodiments. Further, within the scope of the present invention, it is possible to modify any component of the embodiment or omit any component from each embodiment.

Reference Signs List 1, 1A pressure sensor 2, 2A pressure detection unit 10 cover 20 connection nut 30 mounting member 32 fluid introduction chamber 40, 40A base 50 diaphragm 52 pressure receiving space 60 pressure detection device 62 glass base 64 pressure detection element 70 ground terminal Pin 72 Terminal pin 74 Hermetic seal 80 Bonding wire 82 Bonding wire for ground 90 Relay board 92 Connector 94 Lead wire

Claims (5)

a diaphragm that receives fluid pressure;
a base forming a pressure-receiving space filled with an insulating medium between itself and the diaphragm;
a pressure detection device disposed in the pressure receiving space for detecting the pressure transmitted to the insulating medium and converting it into an electrical pressure signal;
a plurality of terminal pins disposed through the base and electrically connected to the pressure detection device within the pressure receiving space, the pressure sensor comprising:
The base has a metal annular portion fixed to the diaphragm, and a ceramic center portion made of an insulating material disposed inside the annular portion,
The pressure detection device is arranged in the central portion,
The pressure sensor according to claim 1, wherein the plurality of terminal pins are arranged to pass through the through-hole of the annular portion, the through-hole being insulated and sealed by a hermetic seal. 2. The pressure sensor of claim 1, wherein the central portion includes a recess recessed away from the diaphragm, and wherein the pressure sensing device is positioned within the recess. 3. The diaphragm-side surface of the pressure sensing device according to claim 2, wherein the surface is flush with the surface of the central portion around the recess or is located within the recess. pressure sensor. The diaphragm-side surface of the pressure detection device protrudes toward the diaphragm with respect to the surface of the central portion around the recess, and an insulating layer is disposed on the surface of the diaphragm facing the pressure detection device. 3. The pressure sensor according to claim 2, wherein: A conductive layer is formed around the recess, and the pressure detection device and the terminal pin for ground are electrically connected via the conductive layer. 5. The pressure sensor according to any one of 4.

Images