KR100982746B1 - Pressure sensor and pressure detection device having the same - Google Patents

Abstract

The present invention relates to a pressure sensor and a pressure detecting device having the same, which is easy to assemble, and solves the problem that the strain gage is peeled off and the connection wiring is broken according to the rotation of the diaphragm during the assembly process. It is for detecting the pressure of a to-be-detected object correctly regardless of a temperature change. The circuit board of the pressure sensor according to the present invention is mounted on the upper end of the lower housing so as to cover the first through hole of the lower housing. The intermediate housing is coupled to the outer side of the lower housing and engages with the lower housing to secure the circuit board. The diaphragm is fitted with an edge portion at an upper end of the intermediate housing to cover the second through hole of the intermediate housing. The upper housing is coupled to the outer side of the intermediate housing and engages with the intermediate housing to fix the diaphragm to seal the second through hole. In addition, the pressure detection device having a pressure sensor according to the present invention detects the temperature of the object directly through the temperature sensor, and calculates the pressure of the object by compensating the sensitivity and the output voltage of the pressure sensor based on the detected temperature. .

Housing, Pressure Sensor, Temperature, Detection, Strain Gage

Description

Pressure sensor and apparatus for detecting pressure having the same

TECHNICAL FIELD The present invention relates to pressure detection technology, and more particularly, to a pressure sensor used to measure the pressure of a fluid and a pressure detection device having the same.

A pressure detection device is a device used to measure the pressure of a fluid used in an object to be detected, such as an automobile or an industrial device, and detects pressure from an electrical signal such as an output voltage or an output current generated according to a pressure applied to a pressure sensor. do.

The pressure sensor used in such a pressure detection device has a structure in which a diaphragm having a strain gage attached to a housing and an amplification circuit board are housed together. At this time, the diaphragm portion is inserted into the object to be detected and outputs an electric signal corresponding to the pressure of the object to be detected to the circuit board. The circuit board amplifies the electrical signal output from the strain gauge of the diaphragm and outputs it to the outside.

The housing has a plurality of divided shapes so that the diaphragm and the circuit board can be installed therein, and are assembled by screw coupling. However, since the clearance between the housing and the diaphragm is not large, a problem may occur in that the diaphragm rotates together with the housing to detach the strain gauge adhered to the diaphragm during assembly of the housing. In addition, a problem may occur in which at least one end of both ends of the connection line connecting the strain gauge and the circuit board is broken.

And since the electrical signal output from the pressure sensor can be changed according to the temperature change, it is necessary to provide a compensation circuit to compensate for this to detect the correct pressure irrespective of the temperature change.

Accordingly, a first object of the present invention is to provide a pressure sensor that is easy to assemble.

A second object of the present invention is to solve the problem that the strain gauge is peeled off the diaphragm generated during the assembly of the housing, and at least one end of the wire connecting the strain gauge and the circuit board is broken. It is to provide.

It is a third object of the present invention to provide a pressure detection device for compensating for the sensitivity and temperature-dependent characteristics of a pressure sensor.

In order to achieve the above object, the present invention provides a pressure sensor comprising a lower housing, a circuit board, an intermediate housing, a diaphragm and an upper housing. The lower housing has a first through hole. The circuit board is mounted on the upper end of the lower housing to cover the first through hole. The intermediate housing is coupled to the outer surface of the lower housing to secure the circuit board and has a second through hole formed at a position corresponding to the first through hole. The diaphragm is fitted with an edge portion at an upper end of the intermediate housing so as to cover the second through hole, and is electrically connected to the circuit board. The upper housing is coupled to the outer surface of the intermediate housing to fix the diaphragm to seal the second through hole, and has a third through hole formed at a position corresponding to the second through hole.

Meanwhile, the present invention provides a pressure detection device including the pressure sensor, the temperature sensor, the sensitivity calculator, the sensitivity compensator, and the pressure calculator. The temperature sensor detects the temperature of the object to be detected. The sensitivity calculator calculates the sensitivity of the pressure sensor. The sensitivity compensator compensates for the sensitivity of the pressure sensor according to the detected temperature. The pressure calculator receives the amplified signal through the output terminal of the pressure sensor and calculates the pressure by compensating the amplified signal according to the detected temperature.

According to the present invention, since the diaphragm is fixed to the intermediate housing via the connecting pin, the diaphragm can be prevented from rotating together in the process of screwing the upper housing to the intermediate housing. As a result, the pressure sensor can be easily assembled, and the problem that the strain gauge adhered to the diaphragm is peeled off, and at least one end of the wire connecting the strain gauge and the circuit board, can be solved.

In addition, since the pressure detecting device according to the present invention directly detects the temperature of the object to be detected through the temperature sensor and calculates the pressure of the object to be detected by compensating the sensitivity and output voltage of the pressure sensor based on the detected temperature, The accuracy of compensation can be increased. As a result, the pressure detecting device according to the present invention can calculate the pressure accurately regardless of the temperature change in the pressure sensor.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

As shown in FIG. 1, the pressure detecting apparatus 100 according to the present invention includes a pressure sensor 10, a temperature sensor 60, a memory unit 70, a controller 80, and an analog-to-digital converter 91. And an analog-to-digital converter (hereinafter referred to as 'D / A converter').

The pressure sensor 10 is installed in the object to be detected and outputs an electric signal corresponding to the pressure at which the object is detected to the controller 80 through the output terminal 39. Detailed description of the pressure sensor 10 will be described later.

The temperature sensor 60 directly detects the temperature of the object to be detected and outputs it to the controller 80.

The memory unit 70 stores a program necessary for controlling the operation of the pressure detection device 100 and data generated while the program is executed, and includes at least one volatile memory device or a nonvolatile memory device. The memory unit 70 stores a sensitivity compensation characteristic of the pressure sensor 10, calculates the sensitivity of the pressure sensor 10, and performs a sensitivity compensation program based on the sensitivity compensation characteristic, and generates the program during execution of the program. Data to be stored.

The controller 80 is a microprocessor that performs the overall control operation of the pressure detection apparatus 100. The controller 80 compensates the sensitivity of the pressure sensor 10 according to the temperature change, and controls the calculation of the pressure of the detected object irrespective of the temperature change.

The A / D converter 91 converts an electrical signal of an analog type output through the output terminal 39 of the pressure sensor 10 into a digital signal and outputs the digital signal to the controller 80.

In addition, the D / A converter 93 converts the digital signal output from the controller 80 into an analog signal and outputs the analog signal to an external device. The D / A converter 93 converts the pressure value of the detected object calculated by the controller 80 into an analog signal and outputs it to an external device. In this case, the external device may be a display device installed in the object to be detected or a test device connected to the DA converter 93.

In particular, the pressure sensor 10 includes a strain gauge 41 having four resistors 41a, 41b, 41c, 41d connected by bridges 43, 45, 47, 49, and a first and second operational amplifier 31. And a circuit board 30 having a 33 and a connection wiring 53 for connecting the strain gauge 41 and the circuit board 30 to each other. The connection wiring 53 includes first to fourth connection wirings 53a, 53b, 53c, and 53d. Strain gauge 41 is attached to the lower surface opposite to the upper surface of diaphragm 40 on which pressure is applied.

At this time, the first bridge 43 is connected to the non-inverting terminal (+) of the second operational amplifier 33 via the first connection line 53a, and the output impedance of the first bridge 43 is the second operational amplifier. It is input to the non-inverting terminal (+) of (33). The second bridge 45 is connected to the power supply terminal Vcc via the second connection line 53b. The third bridge 47 is connected to the ground terminal GND through the third connection line 53c. The fourth bridge 49 is connected to the non-inverting terminal (+) of the first operational amplifier 31 via the fourth connection line 53d, and the output impedance of the fourth bridge 49 is the first operational amplifier ( 31 is input to the non-inverting terminal (+). The output signal of the first operational amplifier 31, that is, the output voltage, is connected to the inverting terminals (−) of the first and second operational amplifiers 31 and 33. The output voltage of the second operational amplifier 33 is fed back to the inverting terminal (-) of the second operational amplifier 33 through the amplifying resistor 35, and the second bridge 45 via the level shift resistance 37. Is fed back to the power supply terminal Vcc. The output voltage of the second operational amplifier 33 is output to the A / D converter 91 through the output terminal 39 and is a voltage before temperature compensation is performed.

The first operational amplifier 31 is used as a voltage follower to eliminate the effect of the output impedance of the first and fourth bridges 43 and 49 on the gain of the second operational amplifier 33. As a result, the second associative amplifier 33 may amplify and output the output voltage at a fixed amplification rate.

The amplification resistor 35 and the level shift resistor 37 are provided on the circuit board 30 as feedback resistors. The level shift resistor 37 sets the operating point of the second operational amplifier 33.

The controller 80 includes a sensitivity calculator 81, a sensitivity compensator 83, and a pressure calculator 85. The sensitivity calculation unit 81 calculates the sensitivity of the pressure sensor 10. The sensitivity compensator 83 compensates the sensitivity of the pressure sensor 10 based on the temperature detected by the temperature sensor 60. The pressure calculator 85 receives the amplified output voltage through the output terminal 39 of the pressure sensor 10, and calculates the pressure of the object to be detected by compensating for the received output voltage based on the detected temperature.

As described above, the pressure detecting apparatus 100 according to the present invention directly detects the temperature of the object to be detected through the temperature sensor 60, and compensates the sensitivity and the output voltage of the pressure sensor 10 based on the detected temperature. Since the pressure of the sieve is calculated, the accuracy of compensation due to temperature changes can be increased. For this reason, the pressure detecting apparatus 100 according to the present invention may calculate the correct pressure irrespective of the temperature change in the pressure sensor 10.

Pressure sensor according to the first example

The pressure sensor 10a of the pressure detecting apparatus 100 according to the present invention may be implemented as shown in FIGS. 2 to 4.

The pressure sensor 10a according to the first example includes a housing 20, a circuit board 30 and a diaphragm 40 embedded in the housing 20. The housing 20 serves to protect the circuit board 30 and the diaphragm 40 from the external environment, and the lower housing 21, the middle housing 23, and the upper housing 25 are stacked and assembled in three dimensions. Has a structure. The lower housing 21 has a first through hole 22. The circuit board 30 is mounted on the upper end of the lower housing 21 so as to cover the first through hole 22. The intermediate housing 23 is coupled to the outer surface of the lower housing 21, and engages with the lower housing 21 to fix the circuit board 30, and the second through hole formed at a position corresponding to the first through hole 22. Has a hole 24. The diaphragm 40 has an edge portion fitted to the upper end of the intermediate housing 23 so as to cover the second through hole 24, and is electrically connected to the circuit board 30. The upper housing 25 is coupled to the outer surface of the intermediate housing 23, engages with the intermediate housing 23, fixes the diaphragm 40 to seal the second through hole, and corresponds to the second through hole 24. And a third through hole 26 formed at the position to be.

The housing 20 divided into three parts as described above may be coupled to each other by a screw coupling method. The inner surface of the intermediate housing 23 is screwed to the outer surface of the lower housing 21. The inner surface of the upper housing 25 is screwed to the outer surface of the intermediate housing 23. That is, threaded threads corresponding to each other are formed on the outer surface of the lower housing 21 and the inner surface of the intermediate housing 23. Threads are formed on the outer surface of the intermediate housing 23 and the inner surface of the upper housing 25 to correspond to each other. And the outer surface of the upper housing 25 is formed with a screw thread that can be screwed to the object to be detected.

In the housing 20 assembled as described above, the first through hole 22, the second through hole 24, and the third through hole 26 are located on the same line, and the first through hole 22 and the third through hole are arranged on the same line. It is connected to the outside through the hole 26. At this time, the circuit board 30 is fixedly installed at the boundary between the first through hole 22 and the second through hole 24, and the diaphragm is disposed at the boundary between the second through hole 24 and the third through hole 26. 40 is fixedly installed. As a result, the second through hole 24 of the assembled housing 20 forms a space enclosed by the circuit board 30 and the diaphragm 40.

In particular, the edge portion of the diaphragm 40 is fitted to the upper end of the intermediate housing 23 via a plurality of connecting pins 51. That is, a plurality of pin insertion holes 27 and 42 into which the connecting pins 51 can be inserted are formed at corresponding portions of the upper end portion of the intermediate housing 23 and the edge portion of the diaphragm 40, respectively.

Thus, since the edge portion of the diaphragm 40 is fitted to the upper end of the intermediate housing 23 through the connecting pins 51, the diaphragm in the process of screwing the upper housing 25 to the intermediate housing 23 40) can be suppressed from rotating together.

On the other hand, the diaphragm 40 includes a strain gauge 41 attached to the lower surface, and the strain gauge 41 is positioned to face the upper surface of the circuit board 30. The strain gauge 41 includes a plurality of semiconductor elements constituting the bridges 43, 45, 47, and 49 and may be attached to the lower surface of the diaphragm 40 using glass welding or an activator curing adhesive. Can be. The activator curing adhesive is an adhesive in which an activator is mixed with a thermosetting adhesive, and is an adhesive that is cured at room temperature.

The strain gauge 41 outputs a signal (output impedance) corresponding to the pressure that the detected object acts on the diaphragm 40 through the third through hole 26. When the diaphragm 40 is deformed under pressure, the strain gauge 41 converts the resistance change generated in response to such deformation into an electrical signal and outputs the change.

The strain gauge 41 is connected to the circuit board 30 through the second through hole 24 via the connection wiring 53, and transmits an output signal to the circuit board 30 through the connection wiring 53. . In this case, a lead wire or a flexible circuit wire may be used as the connection wire 53.

As a material of the diaphragm 40, a metal material having high strength characteristics capable of withstanding the high pressure acting on the object to be detected is required. Since the strain gauge 41 including the plurality of semiconductor elements is attached to the diaphragm 40 by low melting glass or an activator curing adhesive, the material of the diaphragm 40 has a low coefficient of thermal expansion. There is a need for a metal material having For example, as a material of the diaphragm 40, Ti, Nb, Al, or Ti, Nb may be added as a precipitation emphasizing material using Fe, Ni, Co, or Fe and Ni as main materials. Diaphragm 40 may be optionally added to the hardening (precipitation hardening type) stainless steel. The diaphragm 40 may be manufactured by pressing, cutting and cold working.

The circuit board 30 amplifies the received signal and outputs the amplified signal to the A / D converter (91 in FIG. 1) through the output terminal 39 at the lower end of the first through hole 22. As the circuit board 30, a ceramic substrate or a printed circuit board may be used. Although the example in which the circuit board 30 is mounted on the upper end of the lower housing 21 has been disclosed, it may be fixed through the connecting pin 51 like the diaphragm 40. Alternatively, the circuit board 30 and the lower housing 21 may be fixed to each other via an adhesive. Here, Vcc represents a power supply terminal and GND represents a ground terminal among the terminals connected to the circuit board 30.

Meanwhile, the first example discloses an example in which the diaphragm 40 is coupled to the intermediate housing 23 by using a connection pin 51 provided separately from the diaphragm 40 and the intermediate housing 23, but is not limited thereto. For example, the connecting pin may be integrally formed with the diaphragm or the intermediate housing. Specifically, the connecting pin may be integrally formed to protrude from the upper end of the intermediate housing. In this case, the diaphragm is provided with a pin insertion hole into which the connecting pin can be inserted. On the contrary, a connecting pin may be formed in the diaphragm, and a pin insertion hole may be formed in the intermediate housing. Alternatively, connecting pins and pin insertion holes may be formed in a zigzag form in the diaphragm and the intermediate housing, respectively.

Pressure sensor according to the second example

As described above, the pressure sensor according to the first example discloses an example in which the diaphragm 40 and the intermediate housing are coupled via a connecting pin, but as shown in FIGS. 5 to 7, the pressure sensor 10b according to the second example. ) May be coupled to each other via the concave-convex (28, 48) formed to correspond to the diaphragm 40 and the intermediate housing (23), respectively.

Since the pressure sensor 10b according to the second example is the same as the pressure sensor 10a according to the first example except for the configuration in which the diaphragm 40 is coupled to the intermediate housing 23, the diaphragm to the intermediate housing 23 is the same. A description will be given with respect to the configuration in which the 40 is coupled.

Concave and convex (28, 48) is formed that can be fitted to the upper portion of the intermediate housing 23 and the corresponding portion of the edge portion of the diaphragm 40. For example, four recessed portions 48a and convex portions 48b are formed at the edge portion of the diaphragm 40. The intermediate housing 23 has an uneven body 28 formed at an upper end thereof as opposed to the uneven 48 of the diaphragm 40.

In particular, the depth of the recessed portion 28a formed in the intermediate housing 23 is formed to be lower than the thickness of the convex portion 48b of the diaphragm 40 so that the diaphragm 40 may protrude to a certain height from the upper end of the intermediate housing 23. do. The reason for this formation is to stably fix the diaphragm 40 by the upper housing 25 coupled to the outer surface of the intermediate housing 23.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to aid understanding, and are not intended to limit the scope of the present invention. In addition to the embodiments disclosed herein, it is apparent to those skilled in the art that other modifications based on the technical idea of the present invention may be implemented. For example, when fitting the diaphragm into the intermediate housing, the connecting pin disclosed in the first example and the unevenness disclosed in the second example may be applied together. In this case, the connecting pin may be interposed between the convex portion of the diaphragm and the recessed portion of the intermediate housing.

1 is a block diagram showing the configuration of a pressure detection device including a pressure sensor according to the present invention.

FIG. 2 is an exploded view showing a first example of the pressure sensor of FIG. 1.

3 is a partial cross-sectional view illustrating a state in which the pressure sensor of FIG. 2 is assembled.

4 is a plan view illustrating the diaphragm to which the strain gauge of FIG. 2 is attached.

5 is an exploded view illustrating a second example of the pressure sensor of FIG. 1.

6 is a partial cross-sectional view illustrating a state in which the pressure sensor of FIG. 5 is assembled.

FIG. 7 is a plan view illustrating the diaphragm to which the strain gauge of FIG. 5 is attached.

Description of the Related Art [0002]

10, 10a, 10b: pressure sensor 20: housing

21: lower housing 23: intermediate housing

25: upper housing 27, 42: pin insertion hole

30: circuit board 40: diaphragm

41: strain range 51: connection pin

60: temperature sensor 70: memory

80: control unit 81: sensitivity calculation unit

83: sensitivity compensation unit 85: pressure calculation unit

91: A / D Converter 93: D / A Converter

100: pressure detection device

Claims (9)

A lower housing having a first through hole; A circuit board mounted to an upper end of the lower housing to cover the first through hole; An intermediate housing coupled to an outer surface of the lower housing to fix the circuit board and having a second through hole formed at a position corresponding to the first through hole; A diaphragm having an edge portion fitted to the upper end of the intermediate housing to cover the second through hole and electrically connected to the circuit board; And an upper housing coupled to an outer surface of the intermediate housing to fix the diaphragm to seal the second through hole and having a third through hole formed at a position corresponding to the second through hole. Pressure sensor. The method of claim 1, The edge portion of the diaphragm to the upper end of the intermediate housing is a pressure sensor, characterized in that coupled via a plurality of connecting pins. The pressure sensor as claimed in claim 2, wherein a plurality of pin insertion holes through which the connecting pins can be inserted are formed in corresponding portions of the upper end portion of the intermediate housing and the edge portion of the diaphragm. The pressure sensor according to claim 1, wherein an unevenness that can be fitted to a corresponding portion of the upper end of the intermediate housing and the edge of the diaphragm is formed. 5. The pressure sensor according to claim 4, wherein the diaphragm is fitted to protrude from an upper end of the intermediate housing. The diaphragm according to claim 3 or 5, wherein the diaphragm is provided on a lower surface, and includes a strain gauge for outputting an electrical signal corresponding to a pressure acting on the diaphragm through the third through hole. And the strain gauge is connected to the circuit board through the second through hole, and transmits the output signal to the circuit board through the connection wire. The pressure sensor of claim 6, wherein the circuit board comprises an output terminal for amplifying the output signal and outputting the output signal to the outside through the lower end of the first through hole. The method of claim 7, wherein Screwed in three dimensions in order of the lower housing, the intermediate housing and the upper housing; Pressure sensor, characterized in that the outer surface of the upper housing is formed with a screw thread that can be screwed to the detected object. A pressure sensor according to claim 7; A temperature sensor for detecting a temperature of the detected object; A sensitivity calculator which calculates a sensitivity of the pressure sensor; A sensitivity compensator for compensating for the sensitivity of the pressure sensor according to the detected temperature; And a pressure calculator configured to receive the amplified signal through an output terminal of the pressure sensor and calculate a pressure by compensating the amplified signal according to the detected temperature.

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