CN219121600U - High-precision pressure sensor and device applied by same - Google Patents
High-precision pressure sensor and device applied by same Download PDFInfo
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- CN219121600U CN219121600U CN202223571580.9U CN202223571580U CN219121600U CN 219121600 U CN219121600 U CN 219121600U CN 202223571580 U CN202223571580 U CN 202223571580U CN 219121600 U CN219121600 U CN 219121600U
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Abstract
The application relates to a high-precision pressure sensor and a device applied to the high-precision pressure sensor, which comprises a metal shell, wherein one end of the metal shell is provided with an open installation cavity, and the other end of the metal shell is provided with a through hole communicated with the installation cavity; the pressure sensing piece is arranged in the mounting cavity and covers the through hole; the conducting ring is arranged in the mounting cavity and is attached to the inner wall of the mounting cavity; the circuit board is arranged in the mounting cavity, the circuit board is provided with a grounding end, the grounding end of the circuit board is contacted with the conducting ring, and the power supply negative electrode of the pressure sensing piece is connected with the grounding end of the circuit board; the pressing component is used for sealing the opening of the mounting cavity and pressing the circuit board on the conducting ring. The power negative pole of forced induction spare in this application is connected on the earth terminal of circuit board, and the earth terminal of circuit board passes through the conducting ring to be connected on metal casing, and at metal casing because of self voltage fluctuation, when being coupled in forced induction spare through parasitic capacitance, forced induction spare can be directly with this interference fluctuation route to ground to eliminate this kind of coupling noise, improve noise interference killing feature.
Description
Technical Field
The application relates to the technical field of sensors, in particular to a high-precision pressure sensor and an application device thereof.
Background
The pressure sensor is internally provided with a ceramic pressure sensor to sense pressure changes. The high nature and low price of ceramic pressure sensors will be the direction of development of pressure sensors, which are being used by more and more users to replace diffused silicon pressure sensors. Ceramic pressure sensor full scale output: 2.0-4.8 mV/V, which is extremely susceptible to environmental noise due to weak signal.
Noise interference can be coupled to analog circuitry in a number of ways, affecting circuit accuracy. Many such noise sources are available and in practical applications it is almost impossible to control them, and usually only the best solution is obtained by knowing the noise coupling path. The most typical EMI (electromagnetic interference) coupling scheme for ceramic pressure sensor applications is listed in fig. 1 below.
As shown in fig. 1, when the housing and the ceramic pressure sensor are in a floating state, there will be a parasitic capacitance between the housing and the ceramic pressure sensor inside thereof, because the ceramic pressure sensor is in a floating state, the housing necessarily fluctuates its own voltage, and signals are output from the ceramic pressure sensor through the parasitic capacitance coupling. The voltage fluctuation of the shell is mainly caused by electromagnetic interference, electromagnetic wave conduction in the air, radiation and the like.
Because the ceramic pressure sensor output signal is weak, the signal-to-noise ratio is too low compared with a diffused silicon piezoresistive sensor, and the signal-to-noise ratio refers to the sensor output signal/noise. The instrument amplifier (differential operational amplifier) has very good common mode rejection capability, and can extract differential signals from stronger common mode noise. The integrated circuit rectifies the disturbance and eventually appears as a dc offset error, and if the disturbance is intermittent, it appears as an imperceptible measurement error.
Disclosure of Invention
In order to improve noise anti-interference capability, the application provides a high-precision pressure sensor and an application device thereof.
The application provides a high accuracy pressure sensor adopts following technical scheme:
a high accuracy pressure sensor comprising:
a metal shell, one end of which is provided with an open installation cavity and the other end of which is provided with a through hole communicated with the installation cavity;
the pressure sensing piece is arranged in the mounting cavity and covers the through hole;
the conducting ring is arranged in the mounting cavity and is attached to the inner wall of the mounting cavity;
the circuit board is arranged in the mounting cavity, the circuit board is provided with a grounding end, the grounding end of the circuit board is in contact with the conducting ring, and the power negative electrode of the pressure sensing piece is connected with the grounding end of the circuit board;
and the pressing assembly is used for sealing the mounting cavity opening and pressing the circuit board on the conductive ring.
Optionally, the compression assembly includes locking lock nut and clamping ring, the clamping ring inlays dress in the conducting ring and butt be in on the circuit board, locking lock nut threaded connection is in on the installation cavity opening and butt be in the clamping ring.
Optionally, the pressing ring is made of plastic.
Optionally, the locking lock nut is provided with a wire outlet hole, and a wire outlet rubber sheath is embedded in the wire outlet hole.
Optionally, the conductive ring is provided with a step surface for the circuit board to butt against, and the grounding end is formed by a circle of metal contact layer arranged on the surface edge of the circuit board and butt against the step surface of the conductive ring.
Optionally, a caulking groove for embedding the pressure sensing element is formed in the mounting cavity, and the conductive ring is arranged at the edge of the opening of the caulking groove and abuts against the surface of the pressure sensing element.
Optionally, the pressure sensing element is a ceramic pressure sensor.
Optionally, the circuit board includes main control chip and connects in main control chip's first input and second input, first input and second input are connected respectively in the positive pole of pressure sensing part's output and output negative pole, be connected with low pass differential filter circuit or low pass filter circuit between first input and the second input.
Optionally, the negative electrode of the power supply of the pressure sensing element is connected with the RC circuit and then connected with the grounding end of the circuit board.
The device provided by the application adopts the following technical scheme:
the device is a refrigerant recovery machine, a vacuum pump or a water pump, and is provided with the high-precision pressure sensor according to any one of the technical schemes.
In summary, the present application includes at least one of the following beneficial technical effects:
the power negative pole of forced induction spare is connected on the earth terminal of circuit board in this application, and the earth terminal of circuit board passes through the conducting ring to be connected on metal casing, from this, through acting as the shield with metal casing, when metal casing is undulant because of self voltage, when forced induction spare through parasitic capacitance coupling, forced induction spare can be direct with this interference fluctuation route to ground to eliminate this kind of coupling noise, improve noise interference killing feature.
Drawings
Fig. 1 is a schematic diagram of parasitic capacitance generation in the related art.
Fig. 2 is a schematic structural diagram of a high-precision pressure sensor.
FIG. 3 is a schematic cross-sectional view of a high-precision pressure sensor.
Fig. 4 is a schematic structural view of the circuit board.
FIG. 5 is a schematic diagram of the connection of a ceramic pressure sensor to the ground of a circuit board.
Fig. 6 is a schematic diagram of a first circuit connection of the circuit board.
Fig. 7 is a schematic diagram of a second circuit connection of the circuit board.
Fig. 8 is a schematic structural view of the refrigerant recovery machine.
Fig. 9 is a schematic diagram of the installation of a control valve in a refrigerant recovery machine.
Reference numerals illustrate: 100. a high-precision pressure sensor; 1. a metal housing; 2. a pressure sensing member; 3. a conductive ring; 4. a circuit board; 5. a compression assembly; 51. locking a lock nut; 52. a compression ring; 6. a through hole; 7. a mounting groove; 8. a grounding end; 9. a fixing hole; 10. a fixing groove; 11. an outgoing line rubber sheath; 12. a housing; 13. a compressor; 14. a fan; 15. a condenser; 16. a control valve; 161. an input interface; 162. an output interface; 17. copper pipe.
Detailed Description
The present application is described in further detail below in conjunction with figures 2-9.
Example 1
A high-precision pressure sensor, as shown with reference to fig. 2 and 3, comprises a metal housing 1, a pressure sensing element 2, a conductive ring 3, a circuit board 4 and a compression assembly 5.
The metal casing 1 is made of a metal material capable of conducting electricity, such as copper, aluminum, zinc, iron, etc., and in this embodiment, the metal casing 1 is made of aluminum based on other factors such as production cost. One end of the metal shell 1 is provided with an open installation cavity, the other end of the metal shell is provided with a through hole 6 communicated with the installation cavity, the through hole 6 is communicated with the outside, the other end of the metal shell 1 is provided with a threaded installation section, the metal shell 1 can be installed on corresponding equipment through the threaded installation section, and liquid or gas in the equipment enters the metal shell 1 through the through hole 6, so that detection and measurement are realized.
The pressure sensing piece 2 is arranged in the installation cavity and covers the through hole 6, the pressure sensing piece 2 is a ceramic pressure sensor, the pressure sensing piece 2 is provided with a power anode, a power cathode, an output anode and an output cathode, the pressure sensing piece 2 senses the pressure of liquid or gas transmitted from the through hole 6, and the pressure sensing piece can be converted into signals to be transmitted from the output anode and the output cathode. Wherein, the chamber bottom of installation chamber is provided with mounting groove 7 around through-hole 6, is provided with the sealing washer in the mounting groove 7, and pressure sensing piece 2 compresses tightly on the sealing washer can realize the isolated seal between installation chamber and the through-hole 6.
The conducting ring 3 is arranged in the installation cavity and is attached to the inner wall of the installation cavity, the conducting ring 3 is made of metal materials, and in the embodiment, the conducting ring 3 is made of copper materials for the purpose of good conductivity of the conducting ring 3. Wherein, be equipped with the caulking groove that is used for supplying the pressure sensing piece 2 to inlay in the installation cavity, conducting ring 3 sets up at the opening border of caulking groove and butt at the surface of pressure sensing piece 2 to can restrict pressure sensing piece 2 in the caulking groove of installation cavity through conducting ring 3, in order to avoid pressure sensing piece 2 to appear removing because of receiving the pressure of liquid or gas.
Referring to fig. 3 and 4, the circuit board 4 is disposed in the mounting cavity, the circuit board 4 has a ground terminal 8, the ground terminal 8 of the circuit board 4 contacts the conductive ring 3, and the power negative electrode of the pressure sensing part 2 is connected to the ground terminal 8 of the circuit board 4. The conductive ring 3 is provided with a step surface for the circuit board 4 to butt against, the grounding end 8 is formed by a circle of metal contact layer which is arranged on the surface edge of the circuit board 4 and butt against the step surface of the conductive ring 3, and the power supply negative electrode of the pressure sensing part 2 is connected to the grounding end 8 of the circuit board 4 in a pin manner.
Referring to fig. 2, a hold-down assembly 5 is provided to seal the mounting cavity opening and hold down the circuit board 4 to the conductive ring 3. Specifically, the compression assembly 5 includes a locking nut 51 and a compression ring 52, the compression ring 52 is made of plastic, the compression ring 52 is embedded in the conductive ring 3 and is abutted to the circuit board 4, when the compression ring 52 is embedded in the conductive ring 3, the top of the compression ring 52 is higher than the top of the conductive ring 3, the locking nut 51 is in threaded connection with an opening of a mounting cavity and is abutted to the compression ring 52, along with the threaded connection rotation of the locking nut 51, the compression ring 52 can be constantly pressed on the compression ring 52, and the circuit board 4 is compressed on the conductive ring 3, so that the grounding end 8 on the circuit board 4 is in tight contact with the conductive ring 3. And the conductive ring 3 can be pressed against the surface of the pressure sensing element 2 by the pressing assembly 5 to effectively define the position of the pressure sensing element 2.
Wherein, in order to avoid locking lock nut 51 when rotatory, conducting ring 3 appears rotating, is provided with fixed orifices 9 on metal casing 1, is provided with the fixed slot 10 that matches with fixed orifices 9 on the outer wall of conducting ring 3, through pegging graft the fastening pin in fixed orifices 9 and fixed slot 10 to in order to avoid the conducting wire ring to appear circumference pivoted condition.
Referring to fig. 2, a wire outlet hole is formed in the locking nut 51, a wire outlet rubber sheath 11 is embedded in the wire outlet hole, and wires on the circuit board 4 pass through the wire outlet rubber sheath 11 and are led out of the pressure sensor. The outgoing rubber sheath 11 can effectively improve the connection tightness and the waterproof property between the outgoing rubber sheath and the electric wires of the circuit board 4.
It should be noted that, before the pressure sensing element 2, the conductive ring 3 and the circuit board 4 are installed on the outer wall and the compression assembly 5 is installed, the installation cavity is filled with waterproof sealing grease so as to further improve the waterproof performance of the pressure sensor.
In this application, the power negative electrode of the pressure sensing element 2 is connected to the grounding end 8 of the circuit board 4, specifically, referring to fig. 5, the power negative electrode of the pressure sensing element 2 is connected to the grounding end 8 of the circuit board 4 after being connected to an RC circuit, the RC circuit includes a resistor R1 and a capacitor C1, and the resistor R1 and the capacitor C1 are connected in parallel and then connected to the grounding end 8 of the circuit board 4. The RC circuit can prevent ESD (static electricity) from damaging the device.
The power supply cathode of the pressure sensing part 2 is connected to the grounding end 8 of the circuit board 4, and the grounding end 8 of the circuit board 4 is connected to the metal shell 1 through the conducting ring 3, so that when the metal shell 1 is coupled to the pressure sensing part 2 through parasitic capacitance due to self voltage fluctuation by taking the metal shell 1 as a shielding body, the pressure sensing part 2 can directly route the interference fluctuation to the ground, thereby eliminating the coupling noise and improving the noise anti-interference capability.
The present application is to further improve the noise immunity of the circuit board 4. Referring to fig. 6 and 7, the circuit board 4 includes a main control chip MUX, and a first input end and a second input end connected to the main control chip MUX, and an amplifier PGA is connected to an output end of the main control chip MUX, wherein the first input end and the second input end are respectively connected to an output positive electrode and an output negative electrode of the pressure sensing element 2, and a low-pass differential filter circuit or a low-pass filter circuit is connected between the first input end and the second input end.
Referring to fig. 6, the low-pass differential filter circuit includes a resistor R1a, a resistor R1b, a capacitor C1a, a capacitor C1b, and a capacitor C2, where the resistor R1a is connected in series to the first input terminal, the resistor R1b is connected in series to the second input terminal, the capacitor C1a and the capacitor C1b are connected in series, the capacitor C1a and the capacitor C1b are connected across the first input terminal and the second input terminal, and a connection point between the capacitor C1a and the capacitor C1b is grounded. The capacitor C2 is connected across the first input terminal and the second input terminal, and is connected in parallel with a series circuit formed by the capacitor C1a and the capacitor C1 b.
Therefore, the resistor R1a, the capacitor C1a, the resistor R1b and the capacitor C1b respectively form two low-pass filters, so that the high-frequency common-mode rejection performance can be effectively reduced, and the input circuit of the amplifier can be isolated from an external signal source, so that overload protection is carried out on the input. The capacitor C2 can effectively reduce ac common mode rejection errors caused by mismatch between the resistor R1a and the capacitor C1a, and between the resistor R1b and the capacitor C1 b.
Referring to fig. 7, the low-pass filter circuit includes a capacitor C1a and a capacitor C1b, where the capacitor C1a and the capacitor C1b are connected in series, the capacitor C1a and the capacitor C1b connected in series are connected across the first input terminal and the second input terminal, the connection point between the capacitor C1a and the capacitor C1b is grounded, and the low-pass filter circuit is simplified in circuit structure, and only retains each input signal to the ground filter capacitor, thereby forming a low-pass filter circuit from each signal to ground.
Example two
The device is a refrigerant recovery machine, a vacuum pump or a water pump, and is provided with the high-precision pressure sensor according to any one of the technical schemes. Similarly, any device only needs to be applied to the high-precision pressure sensor, and the embodiment is not particularly limited. The refrigerant recovery machine will be described as an example of the apparatus. Referring to fig. 8 and 9, the refrigerant recovery machine includes a casing 12 and a compressor 13 provided in the casing 12, a fan 14 is provided at one side of the compressor 13, a condenser 15 is provided at the other side of the compressor 13, a control valve 16 is connected to the compressor 13, and the control valve 16 is connected to the condenser 15 through a copper pipe 17. The control valve 16 is provided with an input port 161 and an output port 162 which extend to the outside of the casing 12, and therefore, the device needing refrigerant recovery is externally connected with the input port 161, the output port 162 is externally connected with a storage tank, the refrigerant is compressed and input into the condenser 15 from the input port 161 through the compressor 13, and is compressed and input into the storage tank from the output port 162 for storage after being condensed by the condenser 15.
The high-precision pressure sensor 100 according to the technical scheme is disposed on the control valve 16, the high-precision pressure sensor 100 can feed back the pressure condition in the control valve 16 to the display table of the refrigerant recovery machine for displaying, and the refrigerant recovery machine in the embodiment can effectively improve the noise anti-interference capability by adopting the high-precision pressure sensor 100.
The foregoing are all preferred embodiments of the present application, and are not intended to limit the scope of the present application in any way, therefore: all equivalent changes in structure, shape and principle of this application should be covered in the protection scope of this application.
Claims (10)
1. A high accuracy pressure sensor, comprising:
a metal shell (1), one end of which is provided with an open installation cavity and the other end of which is provided with a through hole (6) communicated with the installation cavity;
a pressure sensing piece (2) which is arranged in the mounting cavity and covers the through hole (6);
the conducting ring (3) is arranged in the mounting cavity and is attached to the inner wall of the mounting cavity;
the circuit board (4) is arranged in the mounting cavity, the circuit board (4) is provided with a grounding end (8), the grounding end (8) of the circuit board (4) is in contact with the conductive ring (3), and the power negative electrode of the pressure sensing piece (2) is connected with the grounding end (8) of the circuit board (4);
and the pressing assembly (5) is used for sealing the opening of the mounting cavity and pressing the circuit board (4) on the conductive ring (3).
2. A high-precision pressure sensor according to claim 1, characterized in that the compression assembly (5) comprises a locking nut (51) and a compression ring (52), the compression ring (52) is embedded in the conductive ring (3) and abuts against the circuit board (4), and the locking nut (51) is in threaded connection with the mounting cavity opening and abuts against the compression ring (52).
3. A high precision pressure sensor according to claim 2, characterized in that the pressure ring (52) is made of plastic material.
4. The high-precision pressure sensor according to claim 2, wherein the locking lock nut (51) is provided with a wire outlet hole, and a wire outlet rubber sheath (11) is embedded in the wire outlet hole.
5. A high-precision pressure sensor according to claim 1, characterized in that the conducting ring (3) is provided with a step surface for the circuit board (4) to abut against, and the grounding end (8) is arranged on the surface edge of the circuit board (4) in a circle of metal contact layer and abuts against the step surface of the conducting ring (3).
6. A high-precision pressure sensor according to claim 1, characterized in that the mounting cavity is provided with a caulking groove for embedding the pressure sensing element (2), and the conductive ring (3) is arranged at the opening edge of the caulking groove and is abutted against the surface of the pressure sensing element (2).
7. A high precision pressure sensor according to claim 1, characterized in that the pressure sensing element (2) is a ceramic pressure sensor.
8. The high-precision pressure sensor according to claim 1, wherein the circuit board (4) comprises a main control chip, and a first input end and a second input end which are connected to the main control chip, the first input end and the second input end are respectively connected to an output positive electrode and an output negative electrode of the pressure sensing piece (2), and a low-pass differential filter circuit or a low-pass filter circuit is connected between the first input end and the second input end.
9. A high-precision pressure sensor according to claim 1, characterized in that the negative electrode of the power supply of the pressure sensing element (2) is connected with the grounding end (8) of the circuit board (4) after being connected with an RC circuit.
10. A device, being a refrigerant recovery machine, a vacuum pump or a water pump, characterized in that the device is provided with a high-precision pressure sensor (100) according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223571580.9U CN219121600U (en) | 2022-12-27 | 2022-12-27 | High-precision pressure sensor and device applied by same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223571580.9U CN219121600U (en) | 2022-12-27 | 2022-12-27 | High-precision pressure sensor and device applied by same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219121600U true CN219121600U (en) | 2023-06-02 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202223571580.9U Active CN219121600U (en) | 2022-12-27 | 2022-12-27 | High-precision pressure sensor and device applied by same |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN219121600U (en) |
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2022
- 2022-12-27 CN CN202223571580.9U patent/CN219121600U/en active Active
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