JP7345174B2 - pressure sensor - Google Patents

Description

The present invention relates to pressure sensors.

Liquid-filled pressure sensors, which house a semiconductor pressure detection device in a pressure-receiving chamber divided by a diaphragm and filled with oil, are installed in refrigeration equipment and air conditioners to detect refrigerant pressure, and are also used in industrial equipment. It is equipped and used to detect various fluid pressures.

The semiconductor pressure detection device is disposed within the pressure receiving chamber, and has a function of converting pressure changes within the pressure receiving space into an electrical signal using a pressure detection element and outputting the electrical signal to the outside.

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

On the other hand, Patent Document 1 discloses a pressure sensor in which a base on which a semiconductor-type pressure detection device is attached is formed of a ceramic material. According to the pressure sensor of Patent Document 1, an insulating effect is exhibited by attaching a semiconductor pressure detection device to a ceramic base, so that the influence of high frequency noise transmitted from the piping system can be effectively suppressed.

Japanese Patent Application Publication No. 2017-146136

According to the pressure sensor disclosed in Patent Document 1, effective noise countermeasures can be achieved by forming the base from a ceramic material, but ceramic materials generally have a high degree of processing difficulty, which leads to high costs. There's a problem.

The present invention has been made in view of such problems, and an object of the present invention is to provide a pressure sensor that can suppress the influence of noise while keeping costs low.

In order to achieve the above object, the pressure sensor of the present invention includes:
a diaphragm that receives fluid pressure;
a base forming a pressure receiving space in which an insulating medium is enclosed between the base and the diaphragm;
a pressure detection device disposed in the pressure receiving space to detect the pressure transmitted to the insulating medium and convert it into an electrical pressure signal;
a plurality of terminal pins arranged through the base and electrically connected to the pressure detection device within the pressure receiving space;
a support member insulated with respect to the base;
A pressure sensor comprising: a plate disposed in the pressure receiving space and supported by the support member at a distance from the base;
The pressure detection device is disposed on the plate, and the insulating medium is interposed between the plate and the base ,
The plate is made of a conductive material, and is electrically connected to one of the terminal pins that is connected to ground;
The support member is characterized in that it is a plurality of support pins that are not connected to the wiring layer of the relay board .

According to the present invention, it is possible to provide a pressure sensor that can suppress the influence of noise while keeping costs low.

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

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view showing a pressure sensor 1 according to this embodiment. FIG. 2 is a longitudinal sectional view of the pressure detection unit 2 according to this embodiment. FIG. 3 is a top view of the pressure detection unit 2. FIG. 4 is a bottom view of a cross section taken along line AA in FIG. 2 of the pressure detection unit 2.

As shown in FIG. 1, the pressure sensor 1 includes a large cylinder part 10a having a circular cross section, for example, and a small cylinder part 10b having a circular, oval, or elliptical cross section arranged coaxially. , has a cover 10 made of resin and having a shape in which the respective ends are molded with step portions 10c interposed therebetween. A pressure detection unit 2 is attached to the inside of the large cylindrical portion 10a 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 threadedly connected, a dish-shaped base 40 that is disposed opposite to the mounting member 30, and a mounting plate. It includes a metal diaphragm 50 whose outer periphery is held between the member 30 and the base 40. The mounting member 30, the base 40, and the diaphragm 50 can be made of, for example, a stainless steel alloy. The outer peripheral parts of the mounting member 30, the base 40, and the diaphragm 50 are integrated by a welded part W formed by circumferential welding.

Further, a cylindrical portion 20a is formed to protrude from the upper end of the connection nut 20. On the other hand, a circular hole 30a is formed in the center of the mounting member 30. After the cylindrical portion 20a and the mounting member 30 are fitted, 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 connecting nut 20 communicate with each other via the through passage 20b.

In FIGS. 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 this 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 attached to the base 40 by means such as welding to seal it. It is fixed in place.

In FIG. 3, three terminal pins 70 and 72 and five support pins 73 are arranged so as to penetrate the base 40. The terminal pins 70, 72 and the support pin 73 are insulated and sealed by a hermetic seal 74 with respect to the through hole of the base 40 through which they are inserted.

One of the terminal pins is a ground terminal pin 70. The two terminal pins 72 other than those for ground are connected to terminals on the wiring layer of the relay board 90 shown in FIG. One ground terminal pin 70 is connected to the ground of the wiring layer of the relay board 90 shown in FIG.

The five support pins 73 support the relay board 90, but are not connected to its wiring layer. Further, the support pin 73 has the same length as the terminal pin 70 and protrudes from the base 40 in both directions.

As shown in FIGS. 1 and 2, a disc-shaped plate 100 is supported by the tips of the support pins 73 and the terminal pins 70 so as to be spaced apart from the base 40. As shown in FIGS. In this embodiment, the plate 100 is made of a conductive material such as SUS, and is bonded to the support pin 73 and the terminal pin 70 with a conductive adhesive. Since the plate 100 is stably supported by the five support pins 73 and terminal pins 70 that constitute the support member, it has excellent vibration resistance (vibration resistance) and the stress applied to each pin 70, 73 is dispersed. , damage to hermetic seals can be reduced. An insulating medium is interposed between the plate 100 and the base 40, which communicate with the pressure receiving space 52. Note that the plate 100 may be supported using only the support pin 73 as a support member. Alternatively, instead of the support pin, another member insulated with respect to the base 40 may be used as the support member.

As shown in FIG. 4, two notches 101 are formed on the outer periphery of the plate 100, corresponding to the terminal pins 72, thereby electrically insulating the terminal pins 72 from the plate 100.

In FIGS. 2 and 3, a semiconductor pressure detection device 60 is arranged in the center of the plate 100. As shown in FIGS. The pressure detection device 60 includes a glass pedestal 62 and a pressure detection element (semiconductor chip) 64 attached to the surface thereof. The pedestal 62 is fixed to the plate 100 using adhesive.

In FIG. 4, the pressure detection element 64 includes a plurality of bonding pads (electrodes) near its outer periphery. Three of the bonding pads are a sensor input power pad 64a, a ground pad 64b, and a sensor output pad 64c. 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 at the sensor output pad 64c is set between 0V or more and 5V or less (preferably 0.5V) depending on the detected pressure. 4.5V or less). Furthermore, the arrangement of the bonding pads is not limited to the above.

In FIG. 4, the sensor input power supply pad 64a, the sensor output pad 64c, and the terminal pin 72, other than the ground pad 64b, in the semiconductor type pressure detection device 60 are passed through the notch 101 so that they do not come into contact with the plate 100. They are connected (wired) using bonding wires 80. Further, in this embodiment, the ground pad 64b is connected (connected) to the diaphragm side surface of the plate 100 via the bonding wire 82. On the other hand, the ground terminal pin 70 is fixed to the side surface of the base of the plate 100 via a conductive adhesive. Therefore, the ground terminal pin 70 and the ground pad 64b are electrically connected via the plate 100. When supporting the plate 100 with a plurality of support pins 73, in addition to improving vibration resistance, the plate 100 does not move easily when connecting (connecting) the bonding wire 82 to the firmly fixed plate 100. This has the advantage of improving and stabilizing bond accuracy.

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, air conditioner, etc. in which the pressure sensor 1 is installed. be done. From this 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, 72, and a signal for pressure detection can be output.

When assembling the pressure sensor 1, the outer circumferential end of the base 40 of the pressure detection unit 2 is placed so as to abut against the stepped portion 10d formed inside the large cylindrical portion 10a of the cover 10. Thereafter, the inside of the cover 10 is filled with resin P from the lower end side of the large cylindrical part 10a and the upper end side of the small cylindrical part 10b (the side from which the lead wire 94 is led out), and the resin P is solidified. Thereby, the electrical structure of the pressure detection unit 2 is fixed in the cover 10 in a sealed manner.

The pressure detection device 60 operates by being supplied with power from an external electric circuit via a terminal pin 72 for input power. When fluid is introduced into the connection nut 20 and enters the fluid introduction chamber 32 inside the mounting member 30, the diaphragm 50 is elastically deformed by the pressure, pressurizing the insulating medium within the pressure receiving space 52. The pressure detection element 64 detects this pressure fluctuation, converts it into an electrical signal, and outputs the electrical signal, that is, the signal for pressure detection, to the outside via the terminal pin 72. Based on the input of the pressure detection signal, the external electric circuit can accurately detect the pressure of the fluid introduced into the connection nut 20.

According to this embodiment, by disposing the pressure detection device 60 on the plate 100, it can be separated from the base 40 and insulated. Furthermore, an insulating medium is interposed between the base 40 and the plate 100. Therefore, even if high-frequency noise is transmitted to the base 40 from an external pipe via the connection nut 20, for example, such noise can be effectively blocked, and the influence on the pressure detection device 60 can be suppressed.

Further, since the pressure detection device 60 is surrounded by the plate 100 made of a conductive material, the plate 100 is charged with electric charges around the pressure detection device 60 or on the liquid medium filled in the pressure receiving space 52. This prevents malfunction of the pressure detection device 60 due to charging.

(Modified example)
The plate 100 can also be formed from an inorganic material such as ceramics or glass, or an insulating material with high heat resistance such as polyamide, polyimide, polyethylene terephthalate (PET), or PPS. In this case, a conductive layer is formed on a part of the plate 100 (at least around the pressure detection device 60) or on the entire surface. Typical materials for the conductive layer include gold, silver, copper, aluminum, and nickel, but high melting point materials such as tungsten and molybdenum may also be used to obtain high voltage durability. In this modification, the ground terminal pin 70 and the ground pad 64b are electrically connected through the conductive layer of the plate 100.

According to this modification, by forming the plate 100 from an insulating material, the insulation with respect to the base 40 is further enhanced, and the noise suppression effect is enhanced. In addition, by forming the conductive layer at least around the pressure detection device 60, the charges that are accumulated around the pressure detection device 60 or the charges that are accumulated in the liquid medium filled in the pressure receiving space 52 are transferred through the conductive layer. The charge is removed, thereby preventing malfunction of the pressure detection device 60 due to charge.

Note 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 embodiments or omit any component in each embodiment.

1 Pressure sensor 2 Pressure detection unit 10 Cover 20 Connection nut 30 Mounting member 32 Fluid introduction chamber 40 Base 50 Diaphragm 52 Pressure receiving space 60 Pressure detection device 62 Glass pedestal 64 Pressure detection element 70 Terminal pin for ground 72 Terminal pin 73 Support Pin 74 Hermetic seal 80 Bonding wire 82 Bonding wire for ground 90 Relay board 92 Connector 94 Lead wire 100 Plate

Claims (3)

a diaphragm that receives fluid pressure;
a base forming a pressure receiving space in which an insulating medium is enclosed between the base and the diaphragm;
a pressure detection device disposed in the pressure receiving space to detect the pressure transmitted to the insulating medium and convert it into an electrical pressure signal;
a plurality of terminal pins arranged through the base and electrically connected to the pressure detection device within the pressure receiving space;
a support member insulated with respect to the base;
A pressure sensor comprising: a plate disposed in the pressure receiving space and supported by the support member at a distance from the base;
The pressure detection device is disposed on the plate, and the insulating medium is interposed between the plate and the base,
The plate is made of a conductive material and is electrically connected to one of the terminal pins that is connected to a ground,
The support member is a plurality of support pins that are not connected to the wiring layer of the relay board.
A pressure sensor characterized by: The pressure sensor according to claim 1, wherein the support member is the support pin and the terminal pin connected to ground. 3. The pressure sensor according to claim 1, wherein notches are formed on the outer periphery of the plate at positions corresponding to terminal pins other than the terminal pins connected to ground among the terminal pins.

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