High-precision refrigerant R290 leakage detection sensor master control circuit of MEMS thermal conductivity chip

Abstract

The utility model discloses a high-precision refrigerant R290 leakage detection sensor master control circuit of an MEMS thermal conductivity chip, which relates to the technical field of refrigerant detection sensing and comprises a power supply unit, a signal sensing unit, a signal differential amplification unit, a data processing unit, an air pressure and humidity compensation unit and a digital output unit. The signal induction unit converts the variable quantity of a refrigerant to be detected into a small electric signal, and the signal differential amplification unit performs differential operation to output the small electric signal; the signal processing unit conditions and amplifies the differential output electric signal into a sampling signal; the data processing unit converts the sampling signal into a digital signal and performs communication output; the air pressure and humidity compensation unit detects air pressure and humidity, and the data processing unit carries out environment air pressure and humidity parameter compensation operation; and the power supply unit supplies power to all the units. According to the main control circuit, the miniaturization of the detection equipment is realized. And meanwhile, the device has the advantages of long service life, simple structure, low power consumption, low cost and the like.

Description

Technical Field

[0001] This utility model relates to the field of refrigerant leakage detection technology, and in particular to a high-precision refrigerant R290 leakage detection sensor main control circuit using a MEMS thermal conductivity chip. Background Technology

[0002] Traditional R290 refrigerant leak detection primarily employs NDIR (non-dispersive infrared) and electrochemical techniques. However, these methods have several shortcomings:

[0003] First, NDIR technology has the following drawbacks: it has high power consumption; complex structure, software and hardware design; and high cost.

[0004] Secondly, electrochemical technology also has obvious drawbacks: its application is limited to a narrow temperature range, requiring strict control of temperature conditions; and the equipment has a relatively short lifespan. Utility Model Content

[0005] This utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the embodiment of this utility model proposes a high-precision refrigerant R290 leakage detection sensor main control circuit using a MEMS thermal conductivity chip. The refrigerant leakage detection using a MEMS thermal conductivity chip has the advantages of long life, resistance to poisoning, wide temperature range, simple structure and hardware, low power consumption, and low cost.

[0006] According to an embodiment of this utility model, a high-precision refrigerant R290 leakage detection sensor main control circuit of MEMS thermal conductivity chip is proposed, which includes the following parts: power supply unit, signal sensing unit, signal differential amplification unit, data processing unit, air pressure and humidity compensation unit, and digital output unit.

[0007] The signal sensing unit includes a first MEMS thermal conductivity chip and a second MEMS thermal conductivity chip, which convert the change in the refrigerant to be detected into a small electrical signal, which serves as the signal input to the signal differential amplification unit.

[0008] The differential amplifier unit is built into the microprocessor chip of the data processing unit. It takes the signal input from the signal sensing unit as an in-phase input and outputs a small electrical signal to achieve common-mode rejection.

[0009] The signal processing unit is built into the microprocessor chip of the data processing unit, and it conditions and amplifies the tiny electrical signal output by the differential amplifier of the signal differential amplifier unit into a sampling signal.

[0010] The data processing unit includes a microprocessor chip, which converts the sampled signals from the signal processing unit into digital signals and outputs them for communication.

[0011] The air pressure and humidity compensation unit includes an air pressure sensor chip and a humidity sensor chip. It inputs the ambient air pressure and humidity parameters of the detected gas to the data processing unit, which then performs environmental air pressure and humidity parameter compensation calculations.

[0012] The power supply unit provides power to the signal sensing unit, signal differential amplification unit, data processing unit, air pressure and humidity compensation unit, and digital output unit.

[0013] Furthermore, the power supply unit has four channels. External power is input through the J1 socket. The first power supply unit includes a power management chip. The first power management chip U1's pin 1 (IN) is connected in parallel with one end of the first capacitor, one end of the second capacitor, and the power input V_SUPPLY. The first power management chip U1's pin 2 (GND) is connected in parallel with the other end of the first capacitor and the other end of the second capacitor to ground. The first power management chip U1's pin 3 is connected to the data processing unit microprocessor chip's pin 20 (PE1 / SECG34). The first power management chip U1's pin 5 (OUT) is connected in parallel with one end of the third capacitor, one end of the fourth capacitor, and one end of the third resistor. The other end of the third resistor is connected to the VHT terminal to provide power output. The other ends of the third capacitor and the other ends of the fourth capacitor are connected in parallel to ground.

[0014] External power is input through socket J1. The second power supply unit includes a power management chip. The first pin (IN) of the second power management chip is connected in parallel with one end of capacitor 13, one end of capacitor 16, and the power input V_SUPPLY. The second pin (GND) of the second power management chip U8 is connected in parallel with the other end of capacitor 13 and the other end of capacitor 16 to ground. The third pin of the second power management chip U8 is connected to the PE0 / SECG33 pin of the microprocessor chip of the data processing unit. The fifth pin (OUT) of the second power management chip U8 is connected in parallel with one end of capacitor 14, one end of capacitor 15, and one end of resistor 7. The other end of resistor 7 is connected to VHT to provide power output. The other ends of capacitor 14 and capacitor 15 are connected in parallel to ground.

[0015] External power is input through socket J1. The third power supply unit includes a power management chip. Pin 1 (IN) of the third power management chip is connected in parallel with one end of capacitor 17, one end of capacitor 20, and the power input V_SUPPLY. Pin 2 (GND) of the third power management chip is connected in parallel with the other end of capacitor 17 and the other end of capacitor 20 to ground. Pin 3 of the third power management chip is connected to pin 22 (PE0 / SECG32) of the data processing unit microprocessor chip. Pin 5 (OUT) of the third power management chip is connected in parallel with one end of capacitor 18, one end of capacitor 19, and one end of resistor 14. The other end of resistor 14 is connected to VHT to provide power output. The other ends of capacitor 18 and capacitor 19 are connected in parallel to ground.

[0016] External power is input through socket J1. The fourth power supply unit includes a power management chip. The IN terminal of pin 1 of the fourth power management chip U10 is connected in parallel with one end of capacitor 21, one end of capacitor 24, and the power input V_SUPPLY. The GND terminal of pin 2 of the fourth power management chip U10 is connected in parallel with the other end of capacitor 21 and the other end of capacitor 24 to ground. The OUT terminal of pin 5 of the fourth power management chip U10 is connected in parallel with one end of capacitor 22, one end of capacitor 23, and the power output VDD terminal, with power output provided by the VDD terminal. The other ends of capacitor 22 and capacitor 23 are connected in parallel to ground.

[0017] Furthermore, the signal sensing unit includes two MEMS thermal conductivity chips, each comprising a thermocouple and a heater. Pin 4 (HEATER1) of the first MEMS thermal conductivity chip, pin 4 (HEATER1) of the second MEMS thermal conductivity chip, pins 7, 8, 2, and 5 (GND) of the first MEMS thermal conductivity chip, and pins 7, 8, 2, and 5 (GND) of the second MEMS thermal conductivity chip are connected in parallel. Pin 3 (TH+) of the first MEMS thermal conductivity chip is connected to one end of the 8th capacitor, and pin 4 (AN0) of the data processing unit microprocessor chip is connected to the second MEMS thermal conductivity chip. The connection is as follows: the first MEMS thermal conductivity chip pin TH- is connected in parallel with the second MEMS thermal conductivity chip pin TH-, one end of the 9th capacitor, and the third pin VCM of the data processing unit microprocessor chip; the other end of the 9th capacitor is grounded; the third pin TH+ of the second MEMS thermal conductivity chip is connected in parallel with the other end of the 8th capacitor and the fifth pin AN1 of the data processing unit microprocessor chip; the power supply unit output VHT is connected in parallel with the sixth pin HEATER2 of the first MEMS thermal conductivity chip and the sixth pin HEATER2 of the second MEMS thermal conductivity chip.

[0018] Furthermore, the data processing unit includes a microprocessor chip. The first pin (VOREG / VREFP) of the microprocessor chip is connected in parallel with one end of the second resistor and one end of the seventh capacitor. The second pin (AVSS / VREFN) of the microprocessor chip is connected in parallel with one end of the seventh capacitor and one end of the sixth capacitor and grounded. The third pin (VCM) of the microprocessor chip is connected in parallel with the first pin (TH-) of the first MEMS thermal conductivity chip of the signal sensing unit and the first pin (TH-) of the second MEMS thermal conductivity chip of the signal sensing unit. The fourth pin (AN0) of the microprocessor chip is connected in parallel with the first MEMS thermal conductivity chip of the signal sensing unit. The EMS thermal conductivity chip's pin 3, TH+, is connected; the microprocessor chip's pin 5, AN1, is connected to the signal sensing unit's second MEMS thermal conductivity chip's pin 3, TH+; the microprocessor chip's pin 16, VMAX, is connected in parallel with one end of the 12th capacitor and the power supply unit's VDD; the microprocessor chip's pin 54, PA4 / SCL, pin 52, PA6 / TX, and the output unit management chip's pin 4, D, are connected in parallel; the microprocessor chip's pin 51, PA7 / SDA / RX, is connected in parallel with one end of the first resistor and the output unit management chip's pin 1, R.

[0019] Pin 48 (PB7 / SEG6) of the microprocessor chip is connected in parallel with pin 2 (RE), pin 3 (DE), and one end of resistor 4 of the output unit management chip; pin 47 (PA0 / ICPDA) of the microprocessor chip is connected to pin 3 (ICPDA) of the third socket; pin 46 (PA2 / ICPCK) of the microprocessor chip is connected to pin 2 (ICPCK) of the third socket; pin 1 (VDD) of the third socket is connected to the power input V_SUPPLY; pin 4 (GND) of the third socket is grounded.

[0020] Further, the air pressure and humidity compensation unit includes an air pressure sensor chip and a humidity sensor chip; the first pin VDDIO of the air pressure sensor chip is connected in parallel with the VDD terminal of the power supply unit, one end of the 10th resistor, one end of the 9th resistor, one end of the 8th resistor, and one end of the 11th capacitor; the other end of the 10th resistor is connected in parallel with the second pin SCK terminal of the air pressure sensor chip and the 24th pin PD5 / SEG30 of the microprocessor chip of the data processing unit; the third pin GNDIO of the air pressure sensor chip is connected in parallel with the fifth pin SDO terminal of the air pressure sensor chip and grounded; the air pressure sensor... The INT pin (pin 7) of the pressure sensor chip is connected in parallel with the PD7 / SEG32 pin (pin 23) of the data processing unit microprocessor chip and the other end of the 8th resistor; the SDI pin (pin 4) of the pressure sensor chip is connected in parallel with one end of the 9th resistor and the PD4 / SEG29 pin (pin 25) of the data processing unit microprocessor chip; the GND pins (pins 8 and 9) of the pressure sensor chip are connected in parallel with the other end of the 11th capacitor to ground; the data from the pressure sensor chip is connected to the data processing unit microprocessor chip through the INT, SDI, and SCK pins to provide pressure detection signal data.

[0021] Pin 7 (ADDR1) and pin 8 (GND) of the humidity sensor chip are connected to ground in parallel with one end of capacitor 10; pin 5 (VDD) of the temperature sensor chip is connected in parallel with the VDD terminal of the power supply unit, the other end of capacitor 10, one end of resistor 11, one end of resistor 12, and one end of resistor 13; pin 2 (ADDR) of the humidity sensor chip is grounded; pin 1 (SDA) of the humidity sensor chip is connected in parallel with the other end of resistor 11 and pin 33 (PC4 / SEG21) of the data processing unit microprocessor chip; pin 3 of the humidity sensor chip is connected in parallel with the other end of resistor 13 and pin 30 (PC7 / SEG24) of the data processing unit microprocessor chip; pin 4 of the humidity sensor chip is connected in parallel with the other end of resistor 12 and pin 34 (PC3 / SEG20) of the data processing unit microprocessor chip.

[0022] Furthermore, pin 1 (R) of the output unit management chip is connected to pin 51 (PA7 / SDA / RX) of the data processing unit microprocessor chip; pin 2 (RE) and pin 3 (DE) of the output unit management chip are connected in parallel to pin 48 (PB7 / SEG6) of the data processing unit microprocessor chip; pin 4 (D) of the output unit management chip is connected in parallel to pin 52 (PA6 / TX) and pin 54 (PA4 / SCL) of the data processing unit microprocessor chip; pin 5 (GND) of the output unit management chip is grounded; pin 6 of the output unit microprocessor chip is connected to one end of resistor 6, and the other end of resistor 6 is connected to pin 2 (A) of socket 1 and pin 1 (A / RXD) of socket 2. The first pin of the anti-static diode is connected in parallel; the B terminal of the 7th pin of the output unit management chip is connected to one end of the 5th resistor, and the other end of the 5th resistor is connected in parallel to the B terminal of the 3rd pin of the 1st socket, the B / TXD terminal of the 2nd pin of the 2nd socket, and the 2nd pin of the anti-static diode; the VCC terminal of the 8th pin of the output unit management chip is connected in parallel to one end of the 5th capacitor and the VDD terminal of the power supply unit; the other end of the 5th capacitor is grounded; the VDD terminal of the 1st pin of the 1st socket, the VDD terminal of the 4th pin of the 2nd socket, and one end of the 1st Zener diode are connected in parallel to the power input V_SUPPL terminal; the GND terminal of the 4th pin of the 1st socket, the GND terminal of the 3rd pin of the 2nd socket, the other end of the 1st Zener diode, and one end of the 3rd pin of the anti-static diode are connected in parallel to ground.

[0023] This invention addresses the problems of traditional R290 refrigerant leak detection methods by utilizing a MEMS thermal conductivity chip for measurement. Signal measurement is completed within the sensor, enabling miniaturization of the detection equipment. It also boasts advantages such as long lifespan, simple structure, low power consumption, and low cost. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram of the first path of the main control circuit and sensor power supply unit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the second power supply unit of the main control circuit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the third channel of the power supply unit of the main control circuit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to an embodiment of this utility model.

[0028] Figure 4 This is a schematic diagram of the fourth channel of the power supply unit of the main control circuit of a high-precision refrigerant R290 leakage detection sensor for a MEMS thermal conductivity chip according to an embodiment of this utility model.

[0029] Figure 5 This is a schematic diagram of the main control circuit signal sensing unit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to an embodiment of the present invention.

[0030] Figure 6 This is a schematic diagram of the main control circuit signal amplification unit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip, which is an example of this utility model.

[0031] Figure 7 This is a schematic diagram of the main control circuit signal processing unit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip, which is an example of this utility model.

[0032] Figure 8 This is a schematic diagram of the air pressure detection principle of the main control circuit and air pressure and humidity compensation unit of a high-precision refrigerant R290 leakage detection sensor for a MEMS thermal conductivity chip, which is an example of this utility model.

[0033] Figure 9 A schematic diagram of the main control circuit, air pressure and humidity compensation unit, and humidity detection principle of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip, as an example of this utility model.

[0034] Figure 10 This is a schematic diagram of the main control circuit digital processing unit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip, which is an example of this utility model.

[0035] Figure 11 This is a schematic diagram of the main control circuit of a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip, which is an example of this utility model. Detailed Implementation

[0036] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0037] Reference Figures 1 to 11 This utility model discloses a high-precision refrigerant R290 leakage detection sensor main control circuit of MEMS thermal conductivity chip. The structure of this electronic module can be divided into six parts, namely, sensor power supply unit, signal sensing unit, signal differential amplification unit, data processing unit, air pressure and humidity compensation unit, and digital output unit.

[0038] Its working principle is as follows: the sensor power supply unit provides the power required for the operation of other parts; the signal sensing unit is used to detect the concentration of the gas being measured and outputs an electrical signal based on the concentration of the gas being measured; the signal differential amplification unit is used to proportionally amplify the electrical signal output by the signal sensing unit; the data processing unit is used to perform digital calculations on the proportionally amplified electrical signal from the signal amplification unit; the digital output unit outputs the data processed by the data processing unit for external use; the air pressure and humidity compensation unit detects the ambient air pressure and humidity parameters of the gas and inputs them to the data processing unit, which then performs environmental air pressure and humidity parameter compensation calculations.

[0039] Specifically, the connection relationship between the various parts is as follows: the signal sensing unit is composed of a MEMS thermal conductivity chip, which senses different concentrations of the gas being measured. The signal sensing unit includes a heater and a thermocouple. After the heater of the MEMS thermal conductivity chip is powered and heated, its thermopile generates a weak differential electrical signal. Then, the differential signal is input to the differential instrumentation amplifier of the data processing unit MCU for proportional amplification. The data processing unit MCU simultaneously collects ambient air pressure and humidity. The MCU combines the amplified data with air pressure and humidity for compensation, and then performs mathematical operations before outputting it to the terminal device by the digital output unit. The sensor power supply unit provides power to each part.

[0040] Reference Figure 1 and Figure 5 The power supply section of the main control circuit of the high-precision refrigerant R290 leakage detection sensor of the MEMS thermal conductivity chip in this embodiment will be further explained as follows:

[0041] The sensor power supply section adopts a multi-channel sensor power supply voltage method. Under the same external environment, by switching multiple power supply voltages, different output signals are obtained, eliminating interference from the external environment, thereby obtaining the required signal value.

[0042] In this implementation, the sensor power supply section adopts a four-way power supply method, and its circuit connection relationship is as follows:

[0043] External power is input through socket J1. The first power supply unit includes a power management chip. The first power management chip U1's pin 1 (IN) is connected in parallel with one end of the first capacitor, one end of the second capacitor, and the power input V_SUPPLY. The first power management chip U1's pin 2 (GND) is connected in parallel with the other end of the first capacitor and the other end of the second capacitor to ground. The first power management chip U1's pin 3 is connected to the data processing unit microprocessor chip's pin 20 (PE1 / SECG34). The first power management chip U1's pin 5 (OUT) is connected in parallel with one end of the third capacitor, one end of the fourth capacitor, and one end of the third resistor. The other end of the third resistor is connected to the VHT terminal to provide power output. The other ends of the third capacitor and the other ends of the fourth capacitor are connected in parallel to ground.

[0044] External power is input through socket J1. The second power supply unit includes a power management chip. The first pin (IN) of the second power management chip is connected in parallel with one end of capacitor 13, one end of capacitor 16, and the power input V_SUPPLY. The second pin (GND) of the second power management chip U8 is connected in parallel with the other end of capacitor 13 and the other end of capacitor 16 to ground. The third pin of the second power management chip U8 is connected to the PE0 / SECG33 pin of the microprocessor chip of the data processing unit. The fifth pin (OUT) of the second power management chip U8 is connected in parallel with one end of capacitor 14, one end of capacitor 15, and one end of resistor 7. The other end of resistor 7 is connected to VHT to provide power output. The other ends of capacitor 14 and capacitor 15 are connected in parallel to ground.

[0045] External power is input through socket J1. The third power supply unit includes a power management chip. Pin 1 (IN) of the third power management chip is connected in parallel with one end of capacitor 17, one end of capacitor 20, and the power input V_SUPPLY. Pin 2 (GND) of the third power management chip is connected in parallel with the other end of capacitor 17 and the other end of capacitor 20 to ground. Pin 3 of the third power management chip is connected to pin 22 (PE0 / SECG32) of the data processing unit microprocessor chip. Pin 5 (OUT) of the third power management chip is connected in parallel with one end of capacitor 18, one end of capacitor 19, and one end of resistor 14. The other end of resistor 14 is connected to VHT to provide power output. The other ends of capacitor 18 and capacitor 19 are connected in parallel to ground.

[0046] External power is input through socket J1. The fourth power supply unit includes a power management chip. The IN terminal of pin 1 of the fourth power management chip U10 is connected in parallel with one end of capacitor 21, one end of capacitor 24, and the power input V_SUPPLY. The GND terminal of pin 2 of the fourth power management chip U10 is connected in parallel with the other end of capacitor 21 and the other end of capacitor 24 to ground. The OUT terminal of pin 5 of the fourth power management chip U10 is connected in parallel with one end of capacitor 22, one end of capacitor 23, and the power output VDD terminal, with power output provided by the VDD terminal. The other ends of capacitor 22 and capacitor 23 are connected in parallel to ground.

[0047] In this embodiment, the power supply chip can be selected as model TLV71310PQDBVRQ1.

[0048] Reference Figure 5 and Figure 11 The main control circuit signal sensing unit of the high-precision refrigerant R290 leakage detection sensor of the MEMS thermal conductivity chip in this embodiment will be further explained as follows:

[0049] The signal sensing unit uses an advanced MEMS thermal conductivity chip as the sensing device. This chip includes a heater and a thermocouple. After a stable voltage is supplied to the heater, it heats the insulating base, and the thermocouple generates a millivolt output. Under the same conditions, when the concentration of the gas being measured is 0, the thermocouple outputs a stable voltage value. If the concentration of the gas being measured changes, the voltage value output by the thermocouple will also change.

[0050] The signal sensing unit includes two MEMS thermal conductivity chips, each comprising a thermocouple and a heater. Pin 4 (HEATER1) of the first MEMS thermal conductivity chip and pin 4 (HEATER1) of the second MEMS thermal conductivity chip are connected in parallel. Pins 7, 8, 2, and 5 (GND) of the first MEMS thermal conductivity chip and pins 7, 8, 2, and 5 (GND) of the second MEMS thermal conductivity chip are also connected in parallel. Pin 3 (TH+) of the first MEMS thermal conductivity chip is connected to one end of the 8th capacitor, and pin 4 (AN0) of the data processing unit microprocessor chip. The first MEMS thermal conductivity chip's pin TH- is connected in parallel with the second MEMS thermal conductivity chip's pin TH-, one end of the 9th capacitor, and the third pin VCM of the data processing unit microprocessor chip; the other end of the 9th capacitor is grounded; the third pin TH+ of the second MEMS thermal conductivity chip is connected in parallel with the other end of the 8th capacitor and the fifth pin AN1 of the data processing unit microprocessor chip; the power supply unit's output VHT is connected in parallel with the sixth pin HEATER2 of the first MEMS thermal conductivity chip and the sixth pin HEATER2 of the second MEMS thermal conductivity chip.

[0051] In this embodiment, the MEMS thermal conductivity chip can be selected as model PTCD20-SMD04 REF.

[0052] Reference Figure 6 and Figure 11 To illustrate with an example of the differential signal amplification section, the signal changes generated by the sensor signal sensing unit enter the signal amplifier as differential signals. DI+ and DI- represent in-phase and differential inputs. In-phase inputs significantly increase the circuit's input impedance, reducing attenuation of weak input signals. Differential inputs allow the circuit to amplify only the differential signal, while only acting as a follower for the common-mode input signal, thus improving the common-mode rejection ratio (CMRR) of the subsequent differential and common-mode signals. The amplifier converts this weak differential signal into a readable ground reference output signal. Both inputs share a common-mode voltage. The differential amplifier suppresses the common-mode voltage, and the remaining voltage, after amplification, appears as a single-ended voltage at the amplifier output. This single-ended voltage is then amplified by a programmable gain amplifier and output to a 24-bit ADC.

[0053] In this embodiment, the TH+ and TH- terminals of the first and second MEMS thermal conductivity chips in the signal sensing unit generate a difference signal based on the change in the detected gas concentration. The first and second MEMS thermal conductivity chips form a common-mode input signal, which is connected to the differential operational amplifier inside the data processing unit for differential amplification and processing.

[0054] Reference Figure 7 and Figure 11The data processing unit is described as follows: The signal processing unit includes an MCU, i.e., a microprocessor chip. After the gas to be measured at different concentrations is sensed by the MEMS thermal conductivity chip, the voltage signal output by the thermocouple of the MEMS thermal conductivity chip is amplified into an analog signal by an operational amplifier, and then converted into a signal recognizable by a digital circuit by an ADC. The MCU performs signal acquisition, transformation, filtering, recognition and other processing to obtain a digital signal that meets the requirements.

[0055] The data processing unit includes a microprocessor chip. Pin 1 (VOREG / VREFP) of the microprocessor chip is connected in parallel with one end of the second resistor and one end of the seventh capacitor. Pin 2 (AVSS / VREFN) of the microprocessor chip is connected in parallel with one end of the seventh capacitor and one end of the sixth capacitor and grounded. Pin 3 (VCM) of the microprocessor chip is connected in parallel with pin 1 (TH-) of the first MEMS thermal conductivity chip of the signal sensing unit and pin 1 (TH-) of the second MEMS thermal conductivity chip of the signal sensing unit. Pin 4 (AN0) of the microprocessor chip is connected in parallel with the first MEMS thermal conductivity chip of the signal sensing unit. Pin 3 (TH+) of the current-conducting chip is connected; pin 5 (AN1) of the microprocessor chip is connected to pin 3 (TH+) of the second MEMS thermal current-conducting chip of the signal sensing unit; pin 16 (VMAX) of the microprocessor chip is connected in parallel with one end of the 12th capacitor and the VDD terminal of the power supply unit; pin 54 (PA4 / SCL) and pin 52 (PA6 / TX) of the microprocessor chip are connected in parallel with pin 4 (D) of the output unit management chip; pin 51 (PA7 / SDA / RX) of the microprocessor chip is connected in parallel with one end of the first resistor and pin 1 (R) of the output unit management chip.

[0056] Pin 48 (PB7 / SEG6) of the microprocessor chip is connected in parallel with pin 2 (RE), pin 3 (DE), and one end of resistor 4 of the output unit management chip; pin 47 (PA0 / ICPDA) of the microprocessor chip is connected to pin 3 (ICPDA) of the third socket; pin 46 (PA2 / ICPCK) of the microprocessor chip is connected to pin 2 (ICPCK) of the third socket; pin 1 (VDD) of the third socket is connected to the power input V_SUPPLY; pin 4 (GND) of the third socket is grounded.

[0057] In this embodiment, the MCU chip model can be selected as: BH67F2762-64LQFP.

[0058] Reference Figure 8 , Figure 9 and Figure 11 The pressure and humidity compensation part of this embodiment will be explained in further detail below:

[0059] The detection accuracy of gas sensors is affected by the environment, with air pressure and humidity being two major influencing factors. Therefore, hardware is used to sample air pressure and humidity, and the MCU obtains the air pressure and humidity values ​​and then performs software algorithm compensation.

[0060] The air pressure and humidity compensation unit includes an air pressure sensor chip and a humidity sensor chip. Pin 1 (VDDIO) of the air pressure sensor chip is connected in parallel with the VDD terminal of the power supply unit, one end of resistor 10, one end of resistor 9, one end of resistor 8, and one end of capacitor 11. The other end of resistor 10 is connected in parallel with pin 2 (SCK) of the air pressure sensor chip and pin 24 (PD5 / SEG30) of the microprocessor chip of the data processing unit. Pin 3 (GNDIO) of the air pressure sensor chip is connected in parallel with pin 5 (SDO) of the air pressure sensor chip to ground. Pin 7 (INT) of the pressure sensor chip is connected in parallel with pin 23 (PD7 / SEG32) of the data processing unit microprocessor chip and the other end of resistor 8; pin 4 (SDI) of the pressure sensor chip is connected in parallel with one end of resistor 9 and pin 25 (PD4 / SEG29) of the data processing unit microprocessor chip; pins 8 and 9 (GND) of the pressure sensor chip are connected in parallel with the other end of capacitor 11; the pressure sensor chip data is connected to the data processing unit microprocessor chip through the INT, SDI, and SCK pins to provide pressure detection signal data.

[0061] Pin 7 (ADDR1) and pin 8 (GND) of the humidity sensor chip are connected to ground in parallel with one end of capacitor 10; pin 5 (VDD) of the temperature sensor chip is connected in parallel with the VDD terminal of the power supply unit, the other end of capacitor 10, one end of resistor 11, one end of resistor 12, and one end of resistor 13; pin 2 (ADDR) of the humidity sensor chip is grounded; pin 1 (SDA) of the humidity sensor chip is connected in parallel with the other end of resistor 11 and pin 33 (PC4 / SEG21) of the data processing unit microprocessor chip; pin 3 of the humidity sensor chip is connected in parallel with the other end of resistor 13 and pin 30 (PC7 / SEG24) of the data processing unit microprocessor chip; pin 4 of the humidity sensor chip is connected in parallel with the other end of resistor 12 and pin 34 (PC3 / SEG20) of the data processing unit microprocessor chip.

[0062] In this embodiment, the barometric pressure detection chip can be selected as CMP201; the humidity detection chip can be selected as HDC3020DEFR.

[0063] Please refer to Figure 10 and Figure 11 Further explanation of the data output unit: The digital output section includes a processing chip. After the signal data is processed by the data processing unit MCU, it is supplied to the terminal device via digital output.

[0064] The output unit management chip's pin 1 (R) is connected to the data processing unit microprocessor chip's pin 51 (PA7 / SDA / RX); the output unit management chip's pins 2 (RE) and 3 (DE) are connected in parallel to the data processing unit microprocessor chip's pin 48 (PB7 / SEG6); the output unit management chip's pin 4 (D) is connected in parallel to the data processing unit microprocessor chip's pins 52 (PA6 / TX) and 54 (PA4 / SCL); the output unit management chip's pin 5 (GND) is grounded; the output unit microprocessor chip's pin 6 is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the first socket's pin 2 (A), the second socket's pin 1 (A / RXD), and an anti-static connection. The diode's pin 1 is connected in parallel; the output unit management chip's pin 7 (B) is connected to one end of the 5th resistor, and the other end of the 5th resistor is connected in parallel to the 3rd pin (B) of the 1st socket, the 2nd pin (B / TXD) of the 2nd socket, and the 2nd pin of the anti-static diode; the output unit management chip's pin 8 (VCC) is connected in parallel to one end of the 5th capacitor and the power supply unit's VDD; the other end of the 5th capacitor is grounded; the 1st pin (VDD) of the 1st socket, the 4th pin (VDD) of the 2nd socket, and one end of the 1st Zener diode are connected in parallel to the power input V_SUPPL; the 4th pin (GND) of the 1st socket, the 3rd pin (GND) of the 2nd socket, the other end of the 1st Zener diode, and one end of the 3rd pin of the anti-static diode are connected in parallel to ground.

[0065] In this embodiment, the data output unit outputs data via RS-485, and its management chip can be selected as TP8485E-SR.

[0066] Based on the above design, a high-precision refrigerant R290 leak detection sensor using a MEMS thermal conductivity chip is presented. This invention utilizes a MEMS thermal conductivity chip for measurement, with signal measurement completed internally, enabling miniaturization of the detection device. It also boasts advantages such as long lifespan, simple structure, low power consumption, and low cost. By employing this design and coordinating several circuit components, the shortcomings of traditional refrigerant leak detectors are effectively reduced.

[0067] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

[0068] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0070] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A main control circuit for a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip, characterized in that, include: Power supply unit, signal sensing unit, signal differential amplification unit, data processing unit, air pressure and humidity compensation unit, digital output unit; The signal sensing unit includes a first MEMS thermal conductivity chip and a second MEMS thermal conductivity chip, which convert the change in the refrigerant to be detected into a small electrical signal, which serves as the signal input to the signal differential amplification unit. The differential amplifier unit is built into the microprocessor chip of the data processing unit. It takes the signal input from the signal sensing unit as an in-phase input and outputs a small electrical signal to achieve common-mode rejection. The signal processing unit is built into the microprocessor chip of the data processing unit, and it conditions and amplifies the tiny electrical signal output by the differential amplifier of the signal differential amplifier unit into a sampling signal. The data processing unit includes a microprocessor chip, which converts the sampled signals from the signal processing unit into digital signals and outputs them for communication. The air pressure and humidity compensation unit includes an air pressure sensor chip and a humidity sensor chip. It inputs the ambient air pressure and humidity parameters of the detected gas to the data processing unit, which then performs environmental air pressure and humidity parameter compensation calculations. The power supply unit provides power to the signal sensing unit, signal differential amplification unit, data processing unit, air pressure and humidity compensation unit, and digital output unit.

2. The main control circuit for a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to claim 1, characterized in that, The power supply unit has four channels. External power is input through the J1 socket. The first power supply unit includes a power management chip. The first power management chip U1's pin 1 (IN) is connected in parallel with one end of the first capacitor, one end of the second capacitor, and the power input V_SUPPLY. The first power management chip U1's pin 2 (GND) is connected in parallel with the other end of the first capacitor and the other end of the second capacitor to ground. The first power management chip U1's pin 3 is connected to the data processing unit microprocessor chip's pin 20 (PE1 / SECG34). The first power management chip U1's pin 5 (OUT) is connected in parallel with one end of the third capacitor, one end of the fourth capacitor, and one end of the third resistor. The other end of the third resistor is connected to the VHT terminal to provide power output. The other ends of the third capacitor and the other ends of the fourth capacitor are connected in parallel to ground. External power is input through socket J1. The second power supply unit includes a power management chip. The first pin (IN) of the second power management chip is connected in parallel with one end of capacitor 13, one end of capacitor 16, and the power input V_SUPPLY. The second pin (GND) of the second power management chip U8 is connected in parallel with the other end of capacitor 13 and the other end of capacitor 16 to ground. The third pin of the second power management chip U8 is connected to the PE0 / SECG33 pin of the microprocessor chip of the data processing unit. The fifth pin (OUT) of the second power management chip U8 is connected in parallel with one end of capacitor 14, one end of capacitor 15, and one end of resistor 7. The other end of resistor 7 is connected to VHT to provide power output. The other ends of capacitor 14 and capacitor 15 are connected in parallel to ground. External power is input through socket J1. The third power supply unit includes a power management chip. Pin 1 (IN) of the third power management chip is connected in parallel with one end of capacitor 17, one end of capacitor 20, and the power input V_SUPPLY. Pin 2 (GND) of the third power management chip is connected in parallel with the other end of capacitor 17 and the other end of capacitor 20 to ground. Pin 3 of the third power management chip is connected to pin 22 (PE0 / SECG32) of the data processing unit microprocessor chip. Pin 5 (OUT) of the third power management chip is connected in parallel with one end of capacitor 18, one end of capacitor 19, and one end of resistor 14. The other end of resistor 14 is connected to VHT to provide power output. The other ends of capacitor 18 and capacitor 19 are connected in parallel to ground. External power is input through socket J1. The fourth power supply unit includes a power management chip. The IN terminal of pin 1 of the fourth power management chip U10 is connected in parallel with one end of capacitor 21, one end of capacitor 24, and the power input V_SUPPLY. The GND terminal of pin 2 of the fourth power management chip U10 is connected in parallel with the other end of capacitor 21 and the other end of capacitor 24 to ground. The OUT terminal of pin 5 of the fourth power management chip U10 is connected in parallel with one end of capacitor 22, one end of capacitor 23, and the power output VDD terminal, with power output provided by the VDD terminal. The other ends of capacitor 22 and capacitor 23 are connected in parallel to ground.

3. The main control circuit for a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to claim 1, characterized in that, The signal sensing unit includes two MEMS thermal conductivity chips, each comprising a thermocouple and a heater. Pin 4 (HEATER1) of the first MEMS thermal conductivity chip, pin 4 (HEATER1) of the second MEMS thermal conductivity chip, pins 7, 8, 2, and 5 (GND) of the first MEMS thermal conductivity chip, and pins 7, 8, 2, and 5 (GND) of the second MEMS thermal conductivity chip are connected in parallel. Pin 3 (TH+) of the first MEMS thermal conductivity chip is connected to one end of the 8th capacitor, and pin 4 (AN0) of the data processing unit microprocessor chip. The first MEMS thermal conductivity chip's pin TH- is connected in parallel with the second MEMS thermal conductivity chip's pin TH-, one end of the 9th capacitor, and the third pin VCM of the data processing unit microprocessor chip; the other end of the 9th capacitor is grounded; the third pin TH+ of the second MEMS thermal conductivity chip is connected in parallel with the other end of the 8th capacitor and the fifth pin AN1 of the data processing unit microprocessor chip; the power supply unit's output VHT is connected in parallel with the sixth pin HEATER2 of the first MEMS thermal conductivity chip and the sixth pin HEATER2 of the second MEMS thermal conductivity chip.

4. The main control circuit for a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to claim 1, characterized in that, The data processing unit includes a microprocessor chip. Pin 1 (VOREG / VREFP) of the microprocessor chip is connected in parallel with one end of the second resistor and one end of the seventh capacitor. Pin 2 (AVSS / VREFN) of the microprocessor chip is connected in parallel with one end of the seventh capacitor and one end of the sixth capacitor and grounded. Pin 3 (VCM) of the microprocessor chip is connected in parallel with pin 1 (TH-) of the first MEMS thermal conductivity chip of the signal sensing unit and pin 1 (TH-) of the second MEMS thermal conductivity chip of the signal sensing unit. Pin 4 (AN0) of the microprocessor chip is connected in parallel with the first MEMS... Pin 3 (TH+) of the thermal conductivity chip is connected; pin 5 (AN1) of the microprocessor chip is connected to pin 3 (TH+) of the second MEMS thermal conductivity chip of the signal sensing unit; pin 16 (VMAX) of the microprocessor chip is connected in parallel with one end of the 12th capacitor and the VDD terminal of the power supply unit; pin 54 (PA4 / SCL) and pin 52 (PA6 / TX) of the microprocessor chip are connected in parallel with pin 4 (D) of the output unit management chip; pin 51 (PA7 / SDA / RX) of the microprocessor chip is connected in parallel with one end of the first resistor and pin 1 (R) of the output unit management chip. Pin 48 (PB7 / SEG6) of the microprocessor chip is connected in parallel with pin 2 (RE), pin 3 (DE), and one end of resistor 4 of the output unit management chip; pin 47 (PA0 / ICPDA) of the microprocessor chip is connected to pin 3 (ICPDA) of the third socket; pin 46 (PA2 / ICPCK) of the microprocessor chip is connected to pin 2 (ICPCK) of the third socket; pin 1 (VDD) of the third socket is connected to the power input V_SUPPLY; pin 4 (GND) of the third socket is grounded.

5. The main control circuit for a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to claim 1, characterized in that, The air pressure and humidity compensation unit includes an air pressure sensor chip and a humidity sensor chip; the first pin (VDDIO) of the air pressure sensor chip is connected in parallel with the VDD terminal of the power supply unit, one end of the 10th resistor, one end of the 9th resistor, one end of the 8th resistor, and one end of the 11th capacitor; the other end of the 10th resistor is connected in parallel with the second pin (SCK) of the air pressure sensor chip and the 24th pin (PD5 / SEG30) of the microprocessor chip of the data processing unit; the third pin (GNDIO) of the air pressure sensor chip is connected in parallel with the fifth pin (SDO) of the air pressure sensor chip to ground; the air pressure sensor... Pin 7 (INT) of the chip is connected in parallel with pin 23 (PD7 / SEG32) of the data processing unit microprocessor chip and the other end of resistor 8; pin 4 (SDI) of the barometric pressure sensor chip is connected in parallel with one end of resistor 9 and pin 25 (PD4 / SEG29) of the data processing unit microprocessor chip; pins 8 and 9 (GND) of the barometric pressure sensor chip are connected in parallel with the other end of capacitor 11; the data from the barometric pressure sensor chip is connected to the data processing unit microprocessor chip through the INT, SDI, and SCK pins to provide barometric pressure detection signal data. Pin 7 (ADDR1) and pin 8 (GND) of the humidity sensor chip are connected to ground in parallel with one end of capacitor 10; pin 5 (VDD) of the temperature sensor chip is connected in parallel with the VDD terminal of the power supply unit, the other end of capacitor 10, one end of resistor 11, one end of resistor 12, and one end of resistor 13; pin 2 (ADDR) of the humidity sensor chip is grounded; pin 1 (SDA) of the humidity sensor chip is connected in parallel with the other end of resistor 11 and pin 33 (PC4 / SEG21) of the data processing unit microprocessor chip; pin 3 of the humidity sensor chip is connected in parallel with the other end of resistor 13 and pin 30 (PC7 / SEG24) of the data processing unit microprocessor chip; pin 4 of the humidity sensor chip is connected in parallel with the other end of resistor 12 and pin 34 (PC3 / SEG20) of the data processing unit microprocessor chip.

6. The main control circuit for a high-precision refrigerant R290 leakage detection sensor based on a MEMS thermal conductivity chip according to claim 1, characterized in that, The output unit management chip's pin 1 (R) is connected to the data processing unit microprocessor chip's pin 51 (PA7 / SDA / RX); the output unit management chip's pins 2 (RE) and 3 (DE) are connected in parallel to the data processing unit microprocessor chip's pin 48 (PB7 / SEG6); the output unit management chip's pin 4 (D) is connected in parallel to the data processing unit microprocessor chip's pins 52 (PA6 / TX) and 54 (PA4 / SCL); the output unit management chip's pin 5 (GND) is grounded; the output unit microprocessor chip's pin 6 is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the first socket's pin 2 (A), the second socket's pin 1 (A / RXD), and an anti-static connection. The diode's pin 1 is connected in parallel; the output unit management chip's pin 7 (B) is connected to one end of the 5th resistor, and the other end of the 5th resistor is connected in parallel to the 3rd pin (B) of the 1st socket, the 2nd pin (B / TXD) of the 2nd socket, and the 2nd pin of the anti-static diode; the output unit management chip's pin 8 (VCC) is connected in parallel to one end of the 5th capacitor and the power supply unit's VDD; the other end of the 5th capacitor is grounded; the 1st pin (VDD) of the 1st socket, the 4th pin (VDD) of the 2nd socket, and one end of the 1st Zener diode are connected in parallel to the power input V_SUPPL; the 4th pin (GND) of the 1st socket, the 3rd pin (GND) of the 2nd socket, the other end of the 1st Zener diode, and one end of the 3rd pin of the anti-static diode are connected in parallel to ground.

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