JP3700944B2 - Pressure sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure sensor that detects the pressure of a medium to be measured.
[0002]
[Prior art]
An example of a pressure sensor that detects the pressure of a medium to be measured made of liquid, gas, or the like is disclosed in Patent Document 1. In this pressure sensor, a semiconductor sensor element is disposed on a metal stem having a pressure introduction hole for introducing the pressure of a medium to be measured through a metal base plate so as to face the pressure introduction hole. The sensor element is electrically connected to a printed board having a hole surrounding the sensor element by wire bonding. Various electronic components having at least an amplification circuit for amplifying the signal detected by the sensor element are mounted on the printed circuit board, and the amplified signal is transmitted from a lead pin provided on the printed circuit board to the terminal. Output to the outside.
[0003]
The sensor element and the printed circuit board are accommodated by 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 the entire upper end of the housing and crimping. Further, a screw portion is formed at the lower portion of the stem, and the pressure sensor is fixed by directly screwing the screw portion into a part of a vehicle engine, for example, a measurement portion.
[0004]
The above-described conventional electrical connection structure of the pressure sensor has a structure in which a lead pin is provided on the printed circuit board, the lead pin and the terminal are electrically connected via solder or the like, and a signal from the sensor element is transmitted to the outside. For this reason, there is a problem in that the electrical connection structure becomes complicated, and a pressure sensor that can easily perform electrical connection has been desired. Therefore, the applicant of the present application has proposed a pressure sensor disclosed in Patent Document 2. Such a pressure sensor includes a connection part electrically connected to the sensor element, an amplification circuit part for amplifying at least an electric signal from the sensor element, and a terminal for transmitting the electric signal amplified by the amplification circuit part to the outside A printed circuit board (circuit board) made of FPC (flexible printed circuit), and accommodated in a housing made of a resin material in a state where the printed board is bent at a predetermined position. A terminal or a power cord to be disposed and the terminal portion of the printed circuit board are electrically connected using solder or the like. With this configuration, since the pressure sensor can transmit the signal of the sensor element to the outside without providing the lead pin, the electrical connection configuration is simplified, and the structure of the pressure sensor itself is simplified and reduced in size. Is possible.
[0005]
[Patent Document 1]
JP-A-3-237332 [Patent Document 2]
Japanese Patent Laid-Open No. 2000-111432
[Problems to be solved by the invention]
However, in the pressure sensor described above, it is necessary to dispose electronic components such as a capacitor for removing external noise and a current adjusting resistor for improving detection accuracy on the printed circuit board. While the number of electronic parts increases, it is desired to further reduce the size.
[0007]
The present invention has been made in view of the above problems, and an object thereof is to provide a pressure sensor that can be further reduced in size.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention converts the pressure into an electrical signal by a sensor element arranged in a state of receiving the pressure of the medium to be measured introduced from the pressure introduction part, as described in claim 1. A pressure sensor that transmits the electrical signal to the outside via a circuit board that includes a sensor connection portion that is electrically connected to the sensor element and a terminal portion that transmits the electrical signal to an external energization path; The circuit board has flexibility, a first arrangement in which an amplification circuit section that is bent between the sensor connection section and the terminal section and at least amplifies the electric signal from the sensor element is disposed. And a second disposing portion for disposing electronic parts , a reinforcing plate is disposed on one of the first and second disposing portions, and the reinforcing plate is supported by the case body And the other of the first and second arrangement portions And characterized by being provided a spacer member to be bonded to the reinforcing plate.
[0009]
Further, in claim 1, as described in claim 2, the second arrangement portion is characterized in that a capacitor for removing at least noise is arranged as the electronic component.
[0010]
Further, in claim 1 or claim 2, as described in claim 3, the circuit board is formed to be bent so that the first placement portion and the second placement portion face each other. It is characterized by becoming.
[0012]
Moreover, in Claim 1 , as described in Claim 4 , the said spacer member is comprised from at least one part of the said electronic component, It is characterized by the above-mentioned.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
[0014]
Hereinafter, an embodiment in which the present invention is applied to a pressure sensor disposed in a measurement unit of a vehicle engine will be described with reference to the accompanying drawings. In FIG. 1, the pressure sensor A mainly includes a lower housing (case body) 1, an upper housing 2, a base plate 3, a sensor element 4, a circuit board 5, and a cord (external energization path) 6. Has been.
[0015]
The lower housing 1 is made of, for example, polyphenylene sulfide (PPS), which is a heat-resistant and creep-resistant synthetic resin material, and is formed by insert molding a pressure introducing portion 1a made of a metal material such as SUM. A screw part 1b is formed in the lower part of the lower housing 1, and the pressure sensor A is fixed to a measurement part in a vehicle engine, for example, by the screw part 1b. In addition, a pressure introduction hole 1c for introducing a measurement medium made of liquid or gas is formed substantially at the center of the pressure introduction portion 1a. The lower housing 1 includes a holder 1d that supports a reinforcing plate described later.
[0016]
The upper housing 2 is formed of a resin material such as PBT, and is disposed and fixed by heat-clamping the opening end of the upper housing 2 with respect to the opening end of the lower housing 1. The circuit board 5 is accommodated. The upper housing 2 has a recess 2a formed in the upper part, and the cord 6 is drawn out from the inside of the upper housing 2 toward the recess 2a. A grommet 2b is disposed in the recess 2a, and, for example, epoxy resin is introduced from above the grommet 2b to fix and hold the cord 6, and to prevent dust and moisture from entering from the base of the cord 6.
[0017]
The base plate 3 is made of a metal material such as Kovar and is formed in a substantially circular shape. In addition, the base plate 3 is fitted to the pressure introducing portion 1a by being fitted with the flange portion 3a and fixed to the upper end portion of the pressure introducing portion 1a in the lower housing 1 by resistance welding. A projecting portion 3b that determines the position of the plate 3 is provided. In addition, a hole 3c for transmitting pressure to the sensor element 4 is provided in the approximate center of the flange 3a.
[0018]
In the sensor element 4, a semiconductor chip 4a having a diaphragm formed by thinly forming a semiconductor substrate such as silicon is disposed on a glass pedestal 4b, and the semiconductor chip 4a and the glass pedestal 4b are joined by anodic bonding. The pressure of the fluid introduced from the pressure introduction path 4c provided in the glass pedestal 4b is received by the diaphragm part, and the displacement amount of the diaphragm part is detected. The sensor element 4 forms resistances to be four pressure-sensitive elements having a piezoresistive effect by diffusing impurities such as boron in a portion corresponding to the diaphragm portion, and each of the resistances is made of a conductive material such as aluminum. A bridge circuit is constituted by a wiring pattern using a material, and the pressure of the fluid is detected by an output voltage of the bridge circuit according to displacement of the diaphragm portion. In addition, the sensor element 4 is formed with a metallized layer on the back surface side of the glass pedestal 4b and joined to the base plate 3 via solder.
[0019]
The circuit board 5 is electrically connected to the sensor element 4 by wire bonding, and is formed by flexible FPC. As shown in FIG. 2, the circuit board 5 made of FPC has a sensor connection portion 5 a wire-bonded to the sensor element 4, an amplification function for amplifying an electric signal from the sensor element 4, an offset voltage of the sensor element 4, and a full A first arrangement part 5b in which an amplification circuit part 7 made of an IC package having a temperature voltage adjustment function for the scale voltage and the like is provided; a chip resistor for adjusting the magnitude of the current applied to the sensor element 4; A second disposing portion 5 c for disposing an electronic component 8 made of a capacitor or the like for removing noise and a terminal portion 5 d for connecting to the cord 6 are provided.
[0020]
In addition, the circuit board 5 is provided between the sensor connection portion 5a and the first placement portion 5b, between the first placement portion 5b and the second placement portion 5c, and between the second placement portion 5c and the second placement portion 5c. It is folded in a multilayered manner at a predetermined location between the terminal portion 5d and the respective portions 5a to 5d are accommodated in a space constituted by the lower housing 1 and the upper housing 2 in a state of facing each other.
[0021]
The sensor connecting portion 5a includes a receiving plate 5e that is attached to the back surface of the circuit board 5 and reinforces the circuit board 5 made of FPC, and a hole 5f that communicates the circuit board 5 and the receiving plate 5e. Wire bonding with the sensor element 4 can be performed through the hole 5f in a state where the circuit board 5 is placed on the base plate 4 together with 5e. Further, the receiving plate 5e can be reliably attached to the lower housing 1.
[0022]
The first disposing portion 5b is provided between the sensor connecting portion 5a and the second disposing portion 5c (between the sensor connecting portion 5a and the terminal portion 5d) and bends a predetermined portion of the circuit board 5. The reinforcing plate 5g is disposed on the non-opposing surface side of the sensor element 4 which is a surface on one side, and the amplifier circuit portion is disposed on the other surface. 7 is surface-mounted and electrically connected to the amplifier circuit section 7 by soldering. The first arrangement portion 5b is fixed on the lower housing 1 in a stable state by the reinforcing plate 5g being supported by a holder 1d attached to the lower housing 1.
[0023]
The second disposing portion 5c is provided between the first disposing portion 5b and the terminal portion 5d (between the sensor connecting portion 5a and the terminal portion 5d), and bends a predetermined portion of the circuit board 5 to form the second disposing portion 5c. It is arranged so as to be positioned above one arrangement part 5b, and removes chip resistance and external noise for adjusting the current value applied to the sensor element 4 from an external power source (not shown) on both sides. An electronic component 8 made up of a capacitor or the like is disposed. Further, the electronic component 8 is bonded to the reinforcing plate 5g via an adhesive so that a part of the electronic component 8 serves as a spacer member, and the second arrangement portion 5c is stably fixed. ing. Note that the electronic component 8 may be disposed only on one surface of the second disposition portion 5c. Further, a dedicated spacer member may be provided in the second arrangement portion 5c for fixing the second arrangement portion 5c. Further, in the embodiment of the present invention, the reinforcing plate 5g is provided in the first arranging portion 5b, the holder 1d for supporting the reinforcing plate 5g is provided, and the reinforcing plate 5g is provided in the second arranging portion 5c. The spacer member to be adhered to is disposed, but a reinforcing plate is disposed in the second disposing portion 5c, a holder for supporting the reinforcing plate is provided, and a first disposing portion is provided in the first disposing portion. The structure which arrange | positions the spacer member adhere | attached on the said reinforcement board may be sufficient.
[0024]
The terminal portion 5d is provided at an end portion of the circuit board 5, and is connected by soldering to a cord 6 that transmits an electric signal detected by the sensor element 4 and adjusted and amplified by the amplifier circuit portion 7 to the outside. .
[0025]
The cord 6 transmits the electric signal adjusted and amplified by the amplifier circuit unit 7 to the outside through the terminal unit 5d. The cord 6 is guided and supported from the recess 2a of the upper housing 2 through the grommet 2b. This is an external energization path led to the outside. The external energization path is not limited to the cord, and for example, a configuration in which a connector pin protrudes from the upper housing and is connected to the outside by a connector may be used.
[0026]
The pressure sensor A includes an electronic component 8 and a first disposing portion 5b in which an amplifier circuit portion 7 is disposed by bending a circuit board 5 made of FPC between a sensor connecting portion 5a and a terminal portion 5d. A second disposing portion 5 c is formed, and the circuit board 5 is accommodated in a space constituted by the lower housing 1 and the upper housing 2. Further, the circuit board 5 is formed by bending so that the first arrangement portion 5b and the second arrangement portion 5c face each other. With the above configuration, the circuit board 5 is arranged in a limited space by bending a single circuit board 5 including the sensor connection part 5a, the amplifier circuit part 7, the electronic component 8, and the terminal part 5d into a multilayer shape. Even if the number of electronic components disposed on the circuit board 5 such as a chip resistor for adjusting the current value applied to the sensor element 4 and a capacitor for removing external noise is increased. The diameters of the lower housing 1 and the upper housing 2 can be reduced, and the pressure sensor can be reduced in size.
[0027]
Further, by providing a capacitor for removing external noise as the electronic component 5c in the second arrangement portion 5c, noise resistance is improved even when a resin material is used for the lower housing 1 and the upper housing 2. It becomes possible to make it.
[0028]
Further, the reinforcing plate 5g is provided on one surface of the first arranging portion 5b, the holder 1d for supporting the reinforcing plate 5g is provided, and the spacer member is bonded to the reinforcing plate 5g to the second arranging portion 5c. By doing so, it is possible to suppress the vibration of the circuit board 5 formed by bending. Further, by adhering at least a part of the electronic component 8 as the spacer member to the reinforcing plate 5g, a dedicated spacer member is not required, and the number of components can be reduced.
[0029]
【The invention's effect】
The present invention relates to a pressure sensor that detects the pressure of a medium to be measured, and the pressure sensor can be miniaturized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a pressure sensor according to an embodiment of the present invention.
FIG. 2 is a diagram showing a circuit board of the pressure sensor same as above.
[Explanation of symbols]
A Pressure sensor 1 Lower housing (case body)
2 Upper housing 3 Base plate 4 Sensor element 5 Circuit board 5a Sensor connection part 5b First arrangement part 5c Second arrangement part 5d Terminal part 6 Cord (external energization path)
7 Amplifier circuit part 8 Electronic parts

Claims (4)

The pressure is converted into an electric signal by a sensor element arranged in a state of receiving the pressure of the medium to be measured introduced from the pressure introducing part, and the sensor connecting part electrically connected to the sensor element and the electric signal A pressure sensor that transmits the electrical signal to the outside via a circuit board that includes a terminal part that transmits to an external energization path, the circuit board having flexibility, the sensor connection part, the terminal part, A first arrangement part that arranges an amplification circuit part that is bent between and amplifies at least the electric signal from the sensor element, and a second arrangement part that arranges an electronic component, A reinforcing plate is disposed on one of the first and second disposed portions, a holder for supporting the reinforcing plate on the case body is provided, and the reinforcing plate is disposed on the other of the first and second disposed portions. Japanese that formed by disposing a spacer member that is bonded to A pressure sensor to be.   2. The pressure sensor according to claim 1, wherein the second disposing portion includes at least a capacitor for removing noise as the electronic component.   3. The pressure sensor according to claim 1, wherein the circuit board is formed to be bent so that the first placement portion and the second placement portion face each other. 4. The pressure sensor according to claim 1 , wherein the spacer member includes at least a part of the electronic component.

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