JP2021060240A - Pressure sensor - Google Patents

Abstract

To provide a pressure sensor with which it is possible to simplify assembly work while suppressing the influence of static electricity.SOLUTION: Provided is a pressure sensor comprising: a diaphragm for receiving the pressure of a fluid; a base for forming a pressure-receiving space filled with an insulating medium between the diaphragm and itself; a pressure detector arranged on the base 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 electrically connected to an external electric circuit and electrically connected to the pressure detector side; and a receive member coupled to the base, for forming a fluid introduction chamber between the diaphragm and itself, into which the fluid is introduced from the fluid piping. An insulating member for prevention of noise propagation is provided closer to the piping side than the diaphragm, and the base is electrically connected to a terminal pin among the plurality of terminal pins that is connected to ground.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure sensor.

A liquid-filled pressure sensor, which houses a semiconductor-type pressure detector in a pressure receiving chamber partitioned by a diaphragm and filled with oil, is installed in refrigerating and cooling equipment and air-conditioning equipment to detect refrigerant pressure, and is also used in industrial equipment. It is equipped 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 a pressure change in the pressure receiving space into an electric signal by a pressure detecting element and outputting it to the outside.

The diaphragm arranged in the pressure receiving space is a flexible metal plate. Therefore, when a potential difference is generated between the pressure detection element of the semiconductor type pressure detection device and the diaphragm and the enclosed oil is charged with static electricity, a problem may occur in the pressure detection element or its output signal. The potential difference between the pressure sensing element and the diaphragm can be caused, for example, by high frequency noise transmitted from the piping system to which the pressure sensor is attached.

Therefore, by further arranging a conductive member (static elimination plate) in the pressure receiving space in which the pressure detecting element is housed and connecting the conductive member to the ground terminal pin using a bonding wire, the above-mentioned problem can be solved. A pressure sensor for eliminating the problem is disclosed in Patent Document 1 below.

Japanese Unexamined Patent Publication No. 2014-178125

Here, according to the pressure sensor disclosed in Patent Document 1, the manufacturing cost increases by providing the conductive member. Further, in order to fully exert the static elimination effect, it is necessary to accurately position the pressure detection element and the conductive member with respect to the base, which complicates the mounting work and may reduce the assembly efficiency. is there.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a pressure sensor capable of simplifying an assembly operation while suppressing the influence of static electricity.

In order to achieve the above object, the pressure sensor of the present invention
The diaphragm that receives the pressure of the fluid and
A base that forms a pressure receiving space in which an insulating medium is sealed between the diaphragm and the diaphragm.
A pressure detection device arranged on the base in the pressure receiving space, detecting the pressure transmitted to the insulating medium, and converting the pressure into an electrical pressure signal.
A plurality of terminal pins electrically connected to an external electric circuit and electrically connected to the pressure detector side,
A pressure sensor including a receiving member connected to the base and forming a fluid introduction chamber into which the fluid is introduced from a pipe of the fluid between the diaphragm and the diaphragm.
An insulating member for preventing noise transmission is provided on the piping side of the diaphragm.
The base is electrically connected to a terminal pin connected to the ground among the plurality of terminal pins.

According to the present invention, it is possible to provide a pressure sensor that can simplify the assembly work while suppressing the influence of static electricity.

FIG. 1 is a vertical cross-sectional view of the pressure sensor according to the first embodiment. FIG. 2 is a bottom view of the cross section taken along the line AA of FIG. FIG. 3 is a diagram similar to FIG. 2 showing a modified example of the first embodiment. FIG. 4 is a top view of the pressure detection unit according to the second embodiment. FIG. 5 is a vertical cross-sectional view of the pressure detection unit according to the second embodiment. FIG. 6 is a vertical cross-sectional view showing the pressure sensor according to the third embodiment. FIG. 7 is a bottom view of the cross section taken along the line BB of FIG.

(First Embodiment)
Hereinafter, the first embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing the pressure sensor 1 according to the first embodiment. FIG. 2 is a bottom view of the cross section taken along the line AA of FIG. As shown in FIG. 1, in the pressure sensor 1, for example, a large cylinder portion 10a having a circular tubular cross section and a small tubular portion 10b having a cross section having an annular shape, an oval shape, an elliptical shape, or the like are arranged coaxially. A resin cover 10 having a shape in which the respective ends are joined to each other via a step portion 10c is provided. A pressure detection unit 2 is attached to the inside of the large cylinder portion 10a of the cover 10.

The pressure detection unit 2 includes a dish-shaped mounting member (receiving member) 30 that supports a connection nut 20 to which a fluid inflow pipe (piping) (not shown) is screwed and connected, and a dish-shaped base that is arranged to face the mounting member 30. 40, and a metal diaphragm 50 whose outer circumference is sandwiched between the mounting member 30 and the base 40 are provided. The mounting member 30, the base 40, and the diaphragm 50 are formed of, for example, a stainless alloy, and their outer peripheral portions are integrated by welding (joint portion W).

Further, a cylindrical portion 20a is formed so as to project from the upper end of the connecting nut 20. On the other hand, a circular hole 30a is formed in the center of the mounting member 30. An insulating member 100 is arranged between the connecting nut 20 and the mounting member 30. The insulating member 100 is formed of an inorganic material such as ceramics or glass, or an insulating material having high heat resistance such as polyamide, polyimide, polyethylene terephthalate (PET) or PPS.

The insulating member 100 has a hollow cylindrical portion 101 and a circular flange portion 102 connected to the lower end of the hollow cylindrical portion 101. The hollow cylindrical portion 101 is interposed between the cylindrical portion 20a of the connecting nut 20 and the circular hole 30a of the mounting member 30, and the circular flange portion 102 is formed on the upper surface of the shoulder portion 20c of the connecting nut 20 and the mounting member 30. It intervenes between the lower surface and the lower surface. As a result, the insulating member 100 maintains insulation by blocking electrical conduction between the connecting nut 20 and the mounting member 30.

When the connecting nut 20 and the mounting member 30 are assembled via the insulating member 100, a metallized layer is formed only on the joint surface of the insulating member 100, and then the connection nut 20 and the mounting member 30 are fixed by brazing or the like. It is preferable to fix it via means. Alternatively, the insulating member 100 can be joined to the connecting nut 20 and the mounting member 30 by using an insulating adhesive. Further, an insulating member may be attached between the connection nut 20 and the pipe connected to the connection nut 20, and in that case, the connection nut 20 and the attachment member 30 can be directly connected. That is, it is sufficient that the insulating member for preventing noise transmission is provided on the piping side of the mounting member 30.

A gangway 20b is formed inside the cylindrical portion 20a, and the inside of the mounting member 30 and the inside of the connecting nut 20, that is, a pipe (not shown) communicate with each other via the gangway 20b.

In FIGS. 1 and 2, the pressure receiving space 52 partitioned by the base 40 and the diaphragm 50 is filled with an insulating liquid medium such as oil. After filling the pressure receiving space with the liquid medium through the opening 40a of the base 40, the balls 40b are fixed to the base 40 by means such as welding as shown by the dotted line in FIG. 1 in order to seal the liquid medium. To.

A semiconductor-type pressure detection device 60 is arranged at the center of the base 40 on the pressure receiving space 52 side. The pressure detection device 60 includes a glass pedestal 62 fixed to the base 40 and a pressure detection element (semiconductor chip) 64 attached to the surface thereof.

In FIG. 2, the pressure detecting element 64 is provided with eight bonding pads (electrodes) in the vicinity of the outer periphery thereof. 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 adjustment pads 64d. However, the number of bonding pads is not limited to eight. In the present embodiment, the sensor input power pad 64a is maintained at 5V, the ground pad 64b is maintained at 0V, and the voltage of the sensor output pad 64c is 0V or more and 5V or less (preferably 0.5V) depending on the detected pressure. Above, it changes in the range of 4.5V or less). Further, the arrangement of the bonding pad is not limited to the above.

A plurality of (8 in this example) terminal pins 70 and 72 are arranged around the semiconductor-type pressure detecting device 60 so as to penetrate 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. Further, as shown by pointillism in FIG. 2, the surface of the base 40 around the pressure detecting device 60 is plated, and the plated surface 40c is formed on the pressure receiving space side. Although the plating of the present embodiment is nickel plating, plating may be performed with another material (for example, gold, copper, etc.) having a lower electric resistance than the stainless steel diaphragm 50.

One of the plurality of terminal pins is a ground terminal pin 70. The seven terminal pins 72 other than those for the ground are connected to the terminals of the wiring layer of the relay board 90 shown in FIG. 1, and one terminal pin 70 for the ground is the wiring layer of the relay board 90 shown in FIG. Connected to the ground.

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 refrigerating / cooling device, an air conditioner, or the like in which a pressure sensor 1 is installed. Will 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, the terminal pins 70, and 72, and a signal for pressure detection can be output.

In FIG. 2, in the semiconductor type pressure detection device 60, the sensor input power supply pad 64a, the sensor output pad 64c, the signal adjustment pad 64d, and the terminal pin 72 other than the ground pad 64b are connected (connected) by a bonding wire 80. ). Further, in the present embodiment, the ground pad 64b is connected (connected) to the ground terminal pin 70 via the bonding wire 82, and the plated surface 40c and the ground terminal pin 70 are connected via the bonding wire 81. Is connected (connected).

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

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

Here, noise may be transmitted to the connecting nut 20 via a pipe (not shown). According to the present embodiment, since the connection nut 20 and the mounting member 30 are insulated via the insulating member 100, it is possible to suppress the transmission of noise to the mounting member 30 side. In addition, the ground pad 64b of the pressure detection element 64 has the same potential as the plating surface 40c of the base 40 via the bonding wires 81 and 82, and has the same potential as the ground of the wiring layer of the relay board 90 via the terminal pin 70. It is considered to be an electric potential.

The ground of the wiring layer of the relay board 90 is connected to the zero potential of the electric circuit provided in the control panel of the refrigerating / cooling device, the air conditioner, etc. in which the pressure sensor 1 is installed via the lead wire 94 (FIG. 1). Will be done. That is, since the plated surface 40c of the base 40 is maintained at a zero potential like the ground pad 64b of the pressure detecting element 64, stable operation of the pressure detecting element 64 can be realized. By adding the static elimination plate described in Japanese Patent Application Laid-Open No. 2014-178125 to the pressure sensor of the present embodiment, a higher noise suppression effect can be exhibited.

Here, since the insulating member 100 is a dielectric material, a part of noise from the connecting nut 20 side may be transmitted to the mounting member 30 side. When noise is transmitted to the diaphragm 50, a potential difference is instantaneously generated between the noise and the liquid medium in the pressure receiving space, and the polarization of the liquid medium is induced, which may disturb the output value of the pressure detection device 60. However, in the configuration having the plated surface 40c, since the electric resistance on the base 40 side is lower than that on the diaphragm 50, most of the noise transmitted from the connecting nut 20 side to the mounting member 30 side via the insulating member 100 Will be transmitted to the ground via the base 40, and the noise transmitted to the diaphragm 50 will be significantly reduced. In particular, by arranging the plating layer 40c having a lower electrical resistance than the diaphragm 50 near the joint portion W of the diaphragm 50, most of the noise transmitted to the diaphragm 50 is transmitted to the base 40 side via the plating layer 40c. The noise transmitted to the diaphragm 50 can be reduced more effectively.

Further, in the above-described embodiment, the plating surface 40c is not formed up to the outer peripheral portion of the base 40, but plating may be applied to a range in contact with the outer peripheral portion of the diaphragm 50. By electrically connecting the plated surface to the diaphragm 50 in this way, it is possible to further reduce the transmission of noise from the connection nut 20 side to the diaphragm 50. Further, when the terminal pins 70 and 72 and the hermetic seal 74 are attached after plating the entire surface of the base 40 and the diaphragm 50 is further welded, the plating layer can be electrically connected to the joint portion W, and the noise reduction effect is enhanced. ..

(Modification example)
FIG. 3 is a diagram similar to FIG. 2 showing a modified example of the first embodiment. In this modification, the terminal pins for signal adjustment are omitted, and only the three terminal pins 70 and 72 connected to the ground pad 64b, the sensor input power pad 64a, and the sensor output pad 64c of the pressure detection element 64'are used as the base. It is attached to 40'. Since the other configurations are the same as those in the above-described embodiment, the same reference numerals are given and duplicate description will be omitted.

Similar to the above-described embodiment, the ground pad 64b of the pressure detection element 64'is made to have the same potential as the plating surface 40c' of the base 40' via the bonding wires 81 and 82, and is connected to the relay board via the terminal pin 70. It has the same potential as the ground of the wiring layer of 90 (FIG. 1).

(Second Embodiment)
FIG. 4 is a top view of the pressure detection unit 2A according to the second embodiment. FIG. 5 is a vertical cross-sectional view of the pressure detection unit 2A according to the second embodiment. In the present embodiment, the plated surface is not formed on the pressure receiving space side of the base 40A made of SUS, and the terminal pin 70 for ground and the base 40A are not connected by a wire.

Instead, an annular member 110 (crosslinked member) is attached to the terminal pin 70 on the upper surface side of the base 40A. The annular member 110 that can be formed by press-molding a metal plate has a disk 111 and a tapered cylinder 112 joined to the outer periphery of the disk 111. A hole 113 is formed in the center of the disk 111.

The annular member 110 can be fitted and attached by inserting the terminal pin 70 into the hole 113, and the disk 111 is joined and fixed to the terminal pin 70 by soldering or the like. At this time, the annular member 110 is pressurized from above to elastically deform the tapered cylinder 112 so as to expand the diameter, so that the lower end thereof abuts and presses against the surface of the base 40 on the radial outer side of the hermetic seal 74. Will be done. As a result, an electrical connection is secured through the annular member 110, and the base 40 is maintained at the same potential with respect to the ground of the wiring layer of the relay board 90 (FIG. 1) via the terminal pin 70. The pressure sensor can be formed by assembling the pressure detection unit 2A to the cover 10 shown in FIG. Since the other configurations are the same as those in the above-described embodiment, the same reference numerals are given and duplicate description will be omitted.

In the present embodiment, it is not necessary to form a plated surface on the base 40A, and it is not necessary to connect the terminal pin 70 and the base 40A with a wire, so that the man-hours for manufacturing the pressure sensor can be further reduced.

If the thickness and material of the SUS base 40A are selected so that the base 40A has a lower electric resistance than the diaphragm 50, the adverse effect of noise from the connection nut 20 side is suppressed as in the first embodiment described above. can do. Further, although not shown in FIG. 5, by plating the outer peripheral surface of the base 40A, the flow of noise from the connection nut 20 side to the diaphragm 50 can be reduced. In this case, it is preferable that the plated surface of the outer peripheral surface is in contact with the annular member 110 and the joint portion W. Of course, the plated surface may be formed on the base 40A of the present embodiment, and the plated surface may be formed so as to be electrically connected to the diaphragm 50.

(Third Embodiment)
FIG. 6 is a vertical cross-sectional view showing the pressure sensor 1B according to the third embodiment. FIG. 7 is a bottom view of the cross section taken along the line BB of FIG.

In the present embodiment, the base 40B is not provided with a ground terminal pin and a through hole through which the terminal pin is inserted. Instead, a circular recess 40d is formed on the upper surface of the SUS base 40B. The lower end of the metal coil spring 120, which is a conductive member, is fitted in the circular recess 40d, and the upper end of the coil spring 120 is a wiring arranged to face the upper surface of the outer peripheral portion of the base 40 of the relay board 90B. It is in contact with the ground (not shown) of the layer. Further, the ground pad 64b of the pressure detecting element 64 is connected (connected) to the plating surface 40Bc via the bonding wire 83. Since the other configurations are the same as those of the first and second embodiments, the same reference numerals are given and duplicate description will be omitted.

At the time of assembly, when the pressure sensor unit 2B is brought into contact with the relay board 90B while interposing the coil spring 120, a compressive force is applied to the coil spring 120 from both ends of the contact, which is generated in the coil spring 120. Both ends are pressed against the base 40B and the relay substrate 90B by the elastic force, and electrical continuity is realized. After that, after the resin P is filled and solidified, the conductive state is fixed.

In the present embodiment, the ground of the wiring layer of the relay board 90B and the base 40B are maintained at the same potential via the metal coil spring 120, and the ground pad of the base 40B and the pressure detecting element 64 are kept at the same potential. It is maintained. Therefore, it is not necessary to provide a terminal pin for the ground, which can reduce the manufacturing cost. A flexible printed circuit board or a lead wire may be used instead of the coil spring 120. Further, by combining this embodiment with the modified example of FIG. 3, it is possible to realize a pressure sensor having only two terminal pins. In this embodiment as well, by forming the plated surface so as to include a position where it is electrically connected to the diaphragm 50, it is possible to suppress the adverse effect of noise entering from the connection nut 20 side as in the first embodiment. Of course.

The present invention is not limited to the above-described embodiment. Further, within the scope of the present invention, it is possible to modify any component of the embodiment or omit any component in each embodiment.

1,1B Pressure sensor 2,2A, 2B Pressure detection unit 10 Cover 20 Connection nut 30 Mounting member 32 Fluid introduction chamber 40, 40', 40A, 40B Base 50 Diaphragm 52 Pressure receiving space 60 Pressure detection device 62 Glass pedestal 64, 64'Pressure detection element 70 Terminal pin for ground 72 Terminal pin 74 Hermetic seal 80 Bonding wire 81, 82, 83 Bonding wire for ground 90, 90B Relay board 92 Connector 94 Lead wire 100 Insulation member 110 An annular member 120 Coil spring

Claims (9)

The diaphragm that receives the pressure of the fluid and
A base that forms a pressure receiving space in which an insulating medium is sealed between the diaphragm and the diaphragm.
A pressure detection device arranged on the base in the pressure receiving space, detecting the pressure transmitted to the insulating medium, and converting the pressure into an electrical pressure signal.
Electrically connected to an external electrical circuit,
A plurality of terminal pins electrically connected to the pressure detector side,
A pressure sensor including a receiving member connected to the base and forming a fluid introduction chamber into which the fluid is introduced from a pipe of the fluid between the diaphragm and the diaphragm.
An insulating member for preventing noise transmission is provided on the piping side of the diaphragm.
The base is a pressure sensor that is electrically connected to a terminal pin connected to the ground among the plurality of terminal pins. The pressure sensor according to claim 1, wherein the insulating member is arranged between a connecting nut connected to the pipe and the receiving member. The pressure sensor according to claim 1 or 2, wherein the base includes a plated plated surface. The pressure sensor according to claim 3, wherein the plated surface and the terminal pin connected to the ground are connected by a bonding wire. The first or second claim, wherein the base is formed of a conductive material, a conductive cross-linking member is provided on a terminal pin connected to the ground, and the cross-linking member is in contact with the base. Pressure sensor. The pressure detector is electrically connected to an external electric circuit via a relay board provided with a wiring layer.
The pressure sensor according to claim 1 or 2, wherein the base is formed of a conductive material, and an elastically deformable conductive member is arranged between the base and the ground of the wiring layer. The ground of the wiring layer is arranged so as to face the upper surface of the outer peripheral portion of the base.
The pressure sensor according to claim 6, wherein the conductive member is a metal coil spring. The pressure sensor according to claim 3, wherein the plating applied to the base is in contact with the diaphragm. The pressure sensor according to claim 8, wherein the plating applied to the base is in contact with a joint portion between the base and the diaphragm.

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