JP2000111432A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor where electrical connection can be simplified and at the same time a circuit part such as an amplification circuit can be inexpensively configured within a limited space. SOLUTION: In a pressure sensor, a pressure is converted into an electric signal by a sensor element 5 being arranged while it receives the pressure of a medium to be measured that is introduced from a pressure introduction hole 12 and the electric signal is supplied to the outside via an external conduction path 9. In the pressure sensor, the sensor connections 20 that are electrically connected to the sensor element 5, an amplification circuit part 7 for amplifying an electric signal from the sensor element 5, and a terminal 8 for supplying the electric signal being amplified by the amplification circuit part 7 to the external conduction path 9 are provided on a printed-circuit board 6 that is made of one FPC. By accommodating the printed-circuit board 6 made of the FPC in housings 3 and 11 while it is bent at a given position according to an accommodation space in the housings 3 and 11, electrical routing can be made easily and the accommodation space in the housings 3 and 11 can be effectively utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor for detecting the pressure of a medium to be measured.

[0002]

2. Description of the Related Art As a pressure sensor for detecting the pressure of a medium to be measured comprising a liquid, a gas or the like, for example, Japanese Patent Application Laid-Open No. 3-27
There is one disclosed in Japanese Patent No. 3332. The pressure sensor has a metal stem having a pressure introduction hole for introducing the pressure of the medium to be measured, a sensor element disposed inside the stem so as to face the pressure introduction hole, and a pressure sensor provided around the sensor element. And a printed circuit board electrically connected to the sensor element by wire bonding. An amplification circuit for amplifying the signal detected by the sensor element is formed on this printed circuit board,
On the upper part of the printed circuit board, a feedthrough capacitor for removing external noise to the sensor element and the circuit board is provided, and a detection signal amplified by the circuit board is output to the outside via a terminal. It has become.

The sensor element and the printed circuit board are housed in a cylindrical metal housing attached to the upper portion of the stem, and a resin terminal housing for guiding and supporting the terminal is provided on the upper portion of the housing. The housing and the terminal housing are closed by bending and crimping the entire upper end of the housing. In addition, a screw portion is formed at a lower portion of the stem, and the pressure sensor is fixed by directly screwing the screw portion into a part of a measuring unit, for example, a vehicle engine.

[0004]

The above-described conventional electric connection structure of the pressure sensor has a capacitor holder for supporting the feedthrough capacitor and a feedthrough capacitor because the feedthrough capacitor for removing external noise is provided. It is necessary to provide a lead pin or the like which is inserted into the terminal and electrically connects the terminal and the printed circuit board, and there is a problem that the electric connection structure tends to be complicated, and a pressure sensor which can easily perform the electric connection is desired. .

Further, an amplification circuit for amplifying a signal detected by the sensor element is formed on the printed circuit board. This amplification circuit is accommodated in a limited space to reduce the size of the pressure sensor. Has to be done. In this case, for example, it is conceivable to form a circuit pattern on both sides of the printed circuit board, but there is a problem that the cost is high.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure sensor which can simplify the electrical connection and inexpensively configure circuit parts such as an amplifier circuit in a limited space.

[0007]

According to the present invention, a pressure is converted into an electric signal by a sensor element arranged in a state of receiving a pressure of a medium to be measured introduced from a pressure introducing hole, and the pressure is converted to an electric signal via an external current path. A pressure sensor adapted to supply the electric signal to the outside, a sensor connection part electrically connected to the sensor element, an amplifier circuit for amplifying an electric signal from the sensor element, and the amplifier circuit And a terminal for supplying the electric signal amplified by the section to the external current path.
The printed board is housed in a housing in a state where the printed board is bent at a predetermined position.

[0008] The sensor connection portion may be configured such that a receiving plate is attached to the printed circuit board to form a hole penetrating the printed circuit board and the receiving plate, and the sensor element and the print element are formed through the hole. It is configured to make electrical connection with the substrate.

Further, a reinforcing plate is attached to the back side of the printed circuit board on which the amplifier circuit section is mounted, and a holder for supporting the reinforcing plate is provided.

Further, the sensor connection section and the amplification circuit section are vertically arranged.

Further, the amplifier circuit section has a function of removing external noise.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pressure sensor according to the present invention converts a pressure into an electric signal by a sensor element arranged in a state of receiving a pressure of a medium to be measured introduced from a pressure introducing hole, and converts the pressure into an electric signal via an external current path. A pressure sensor configured to supply a leverage electric signal to the outside, a sensor connection part electrically connected to the sensor element by wire bonding, an amplification circuit unit for amplifying an electric signal from the sensor element, And a terminal for supplying the electric signal amplified by the amplifier circuit section to the external power supply path, on a printed circuit board made of one FPC. By housing the FPC printed circuit board in the housing in a state where it is bent at a predetermined position in accordance with the storage space in the housing, electric wiring can be easily performed, and the storage space in the housing can be reduced. It can be used effectively. In this case, the cost can be reduced by using an FPC provided with a circuit pattern only on one side.

[0013] The sensor connection portion may be formed by attaching a receiving plate to a printed circuit board made of the FPC, forming a hole penetrating the printed circuit board and the receiving plate, and forming the sensor element through the hole. And the printed circuit board are electrically connected to each other, so that the printed circuit board can be easily bonded to the printed circuit board, and the printed circuit board can be reliably supported by the housing.

Also, a reinforcing plate is attached to the back side of the printed circuit board on which the amplifying circuit section is mounted, and a holder for supporting the reinforcing plate is provided. The portion can be stably supported in the housing.

Further, by arranging the sensor connection portion and the amplification circuit portion vertically, a circuit portion including the amplification circuit portion can be divided into upper and lower portions, so that a limited storage space in the housing is provided. It can be used effectively.

Further, since the amplifier circuit has a function of removing external noise, it is not necessary to separately provide a feedthrough capacitor, so that the structure can be simplified and the space can be saved.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 4 show an embodiment of the present invention. The pressure sensor according to the present embodiment detects the pressure of a medium to be measured such as water, oil or gas, and is formed by insert-molding a metal pressure introducing cylinder 2 having a mounting screw portion 1 at a lower portion. A lower housing 3 made of resin, a base plate 4 disposed at an upper end of the pressure introducing cylinder 2, a semiconductor sensor element 5 disposed on the base plate 4 under pressure, and a sensor element 5. Printed circuit board 6 electrically connected to the circuit board, and amplifying circuit section 7 mounted on printed circuit board 6
A terminal 8 provided at an end of the printed circuit board 6 for supplying an output signal to the outside, and a cord 9 connected to the terminal 8
And an upper housing 11 made of synthetic resin and provided with a drawer 10 for supporting the cord 9.

The lower housing 3 is made of a heat-resistant and creep-resistant synthetic resin material, for example, polyphenylene sulfide (PPS). The metal pressure introducing cylinder 2 is integrally insert-molded and the sensor element 5 is housed therein. It is a function to perform. The pressure introducing cylinder 2 insert-molded in the lower housing 3 is opened at the inlet side, and the pressure of the medium to be measured is transmitted through the pressure introducing hole 12 to the sensor element 5.
Serve to communicate to A screw portion 1 made of a synthetic resin is formed integrally with the lower housing 3 at a lower portion of the lower housing 3, and the screw portion 1 is screwed and fixed to a measuring portion composed of, for example, a vehicle engine.

When the screw portion 1 is formed integrally from the lower housing 3 and attached to the measuring portion in this manner, there is a concern that the joint between the pressure-introduced cylinder 2 and the lower housing 3 formed by insert molding is airtight. In this embodiment, as shown in FIG. 2, a seal member 13 is interposed at a boundary B between the lower housing 3 and the pressure introducing cylinder 2. This seal member 13 injects liquid resin into the interface between the lower housing 3 and the pressure introducing cylinder 2 by vacuum injection after insert molding,
Thereafter, the resin adhered to an excess portion is washed away by washing, and then the resin is formed by a protect seal (trade name: Nippon Loctite) technology of thermosetting the resin.

By doing so, the seal member 13 enters the joint portion between the pressure introducing cylinder 2 and the lower housing 3 without any gap, thereby ensuring airtightness and improving the reliability of the measured pressure.

Further, in this embodiment, by providing the uneven portion 14 at the contact portion of the pressure introducing cylinder 2 with the lower housing 3, the resin forming the lower housing 3 enters the uneven portion 14 to improve the airtightness and strength. Will do. Also,
Further, by providing the above-described sealing member 13 at the boundary portion B in addition to the uneven portion 14, further airtightness can be secured.

The pressure introducing cylinder 2 is formed in a cylindrical shape by a metal material made of, for example, stainless steel, and has an inlet for opening one end of the pressure introducing hole 12 to introduce pressure.
At the other end, a mounting portion 15 for disposing the base plate 4 is provided.

The base plate 4 is made of a substantially circular member and made of a metal material such as Kovar having a coefficient of thermal expansion close to the coefficient of thermal expansion of the sensor element 5. Flange 1 for disposing on mounting portion 15
6, a projection 17 which fits into the pressure introducing hole 12 of the pressure introducing cylinder 2 to determine the disposition position of the base plate 4 with respect to the pressure introducing cylinder 2, and a sensor element which communicates with the pressure introducing hole 12. 5 are formed with holes 18 for transmitting pressure.

The base plate 4 has a flange portion 1 of the base plate 4.
6 is welded to the mounting portion 15 of the pressure introducing cylinder 2 so as to be airtightly disposed on the pressure introducing cylinder 2. The base plate 4 is interposed between the sensor element 5 and the pressure introducing cylinder 2 and serves as an intermediate member for absorbing a difference in deformation due to a difference in thermal expansion coefficient between the two.

The sensor element 5 converts the pressure of the medium to be measured into an electric signal. The sensor element 5 is formed by sealing a thin diaphragm on which a semiconductor strain gauge is formed on a glass base by anodic bonding. The glass pedestal is formed with a hole 19 for transmitting the pressure to the diaphragm. Also,
The sensor element 5 has a metallized layer formed on a surface facing the glass pedestal and the base plate 4.
8 and the hole 19 of the sensor element 5 are combined so as to communicate with each other, and are mounted in an airtight manner by soldering on the base plate 4.

As shown in FIGS. 3 and 4, the printed board 6 is electrically connected to the sensor element 4 by wire bonding, and is formed by an FPC (Flexible Printed Circuit). This FP
A printed circuit board 6 made of C has a sensor connection portion 20 wire-bonded to the sensor element 5,
Amplifying circuit section 7 for amplifying an electric signal from the apparatus and performing a predetermined noise removing process, and for connecting to an external current path including, for example, a cord 9 for supplying the electric signal amplified by the amplifying circuit section 7 to the outside. Are all provided on one printed circuit board 6. This printed circuit board 6
It is made of a PC, is bent at a predetermined location, and is housed in a housing constituted by the lower housing 3 and the upper housing 11, and has a limited space for the sensor element 5, the amplifier circuit section 7, and the terminal 8. Since the wiring can be freely routed in the inside, it is suitable for forming a pressure sensor.

In this case, for example, by arranging the sensor connection section 20 and the amplification circuit section 7 vertically, the amplification circuit section 7
Can be divided into upper and lower parts, so that the limited storage space in the housing can be effectively utilized.

The sensor connector 20 has a receiving plate 21 attached to the back surface of the printed circuit board 6 to reinforce the printed circuit board 6 made of FPC, and a hole 22 for communicating the printed circuit board 6 with the receiving plate 21 is provided. In a state where the printed circuit board 6 is placed on the base plate 4 together with the receiving plate 21, wire bonding with the sensor element 5 through the hole 22 is enabled. Further, the receiving plate 21 enables the lower housing 3 to be securely mounted.

The amplifier circuit section 7 is provided as an IC package having a function of removing external noise by the amplifier circuit section 7, a temperature compensation function, a voltage range adjustment function, and the like. There is no need to provide this, and the electrical connection can be simplified. The amplifying circuit section 7 composed of this IC package is provided between the sensor connection section 20 and the terminal 8, and the printed circuit board 6 composed of FPC is provided. The reinforcing plate 23 is adhered to one surface, and the amplifier circuit 7 is surface-mounted on the other surface, and is electrically connected to the printed circuit board 6 by soldering. The amplification circuit section 7 includes a reinforcing plate 23 and a holder 24.
, And is stably fixed on the lower housing 3.

The terminal 8 is provided at an end of the printed circuit board 6 and is connected to an external current path composed of a cord 9 for supplying a signal detected by the sensor element 5 and amplified by the amplifier circuit section 7 to the outside. Is what is done.

The cord 9, which is an external current path, is guided via a grommet 25 by a drawer 10 of the upper housing 11 which accommodates the sensor element 5, the printed circuit board 6 and the amplifier circuit 7 in combination with the lower housing 3. It is supported and led out of the upper housing 11.

The upper housing 11 is formed of, for example, a resin material made of polybutylene terephthalate (PBT). A concave portion 26 is formed in the upper portion. The cord 9 is drawn out of the upper housing 11 toward the concave portion 26. The epoxy resin flows in from the upper part of the grommet 25 provided in the concave portion 26 and is hardened to fix and support the cord 9 and prevent dust and moisture from entering from the base of the cord 9. Like that.

After being combined with the lower housing 3, the upper housing 11 is fixed to the lower housing 3 by heat caulking so that the entire lower end of the upper housing 11 is bent inward.

In the present embodiment, only the output of the pressure sensor is drawn out of the upper housing by the external current path composed of the cord 9. An external conduction path configured to perform connection with a connector may be used.

Further, a drawer is provided on the lower housing 3 side without providing the upper housing 11 as shown in the above-described embodiment, and a simple cover member having no drawer is provided as the upper housing. A pressure sensor may be formed by caulking and fixing in combination with the lower housing.

The F used as the printed circuit board 6
A PC can be inexpensively constructed by using a wiring pattern on one side, but if necessary, a more complicated circuit can be constructed by using a printed circuit board composed of an FPC with wiring patterns on both sides. You can do it.

[0037]

As described above, according to the present invention, electrical connection can be simplified, and a circuit portion such as an amplifier circuit can be configured inexpensively within a limited space.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of one embodiment of the present invention.

FIG. 3 is a plan view showing a printed circuit board applied to one embodiment of the present invention.

FIG. 4 is a side view showing a printed circuit board applied to one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 2 pressure introducing cylinder 3 lower housing 5 sensor element 6 printed circuit board 7 amplifying circuit section 8 terminal 9 cord (external conduction path) 11 upper housing 12 pressure introducing hole 20 sensor connecting section 21 receiving plate 22 hole 23 reinforcing plate 24 holder

Claims (5)

[Claims] 1. A pressure sensor converts a pressure into an electric signal by a sensor element disposed under a pressure of a medium to be measured introduced through a pressure introducing hole, and supplies the electric signal to the outside via an external current path. The pressure sensor as described above, a sensor connector electrically connected to the sensor element, an amplifier circuit for amplifying an electrical signal from the sensor element, and an electrical signal amplified by the amplifier circuit A pressure sensor comprising: a terminal to be supplied to the external current path; and a printed circuit board made of an FPC, wherein the printed circuit board is folded at a predetermined position and housed in a housing. 2. The sensor connection portion, wherein a receiving plate is attached to the printed board, a hole is formed through the printed board and the receiving plate, and the sensor element and the print are formed through the hole. The pressure sensor according to claim 1, wherein the pressure sensor is configured to be electrically connected to a substrate. 3. The pressure sensor according to claim 1, wherein a reinforcing plate is attached to a back side of the printed circuit board on which the amplifier circuit section is mounted, and a holder for supporting the reinforcing plate is provided. 4. The pressure sensor according to claim 1, wherein the sensor connection portion and the amplifier circuit portion are arranged vertically. 5. The pressure sensor according to claim 1, wherein the amplifier circuit has a function of removing external noise.