A household combustible gas detector with exponential curve correction function

Abstract

The invention relates to the field of fire alarm technology, and in particular to a household combustible gas detector with an exponential curve correction function, which can improve detection accuracy and ensure communication effect. The CPU module comprises a single-chip microcomputer U1, and the single-chip microcomputer U1 is electrically connected to a calibration signal processing circuit and a bus communication circuit. The bus communication circuit comprises an optocoupler U4, and pin 1 of the optocoupler U4 is connected to a 3.3V power supply, pin 2 is connected to pin 42 of the single-chip microcomputer U1 through a resistor R37, pin 4 is connected to a DC+ direct current power supply, and pin 3 is connected to one end of a resistor R30. The other end of the resistor R30 is connected to the base of a transistor Q3 and one end of a resistor R31. Pin 3 of the transistor Q3 is connected to one end of a resistor R29, and the other end of the resistor R29 is connected to one end of a resistor R33, an anode of a diode D9, and pin 3 of a common cathode diode D7. Pin 2 of the common cathode diode D7 is connected to pin 1 of a common anode diode D8, one end of a capacitor C28, one end of a common cathode voltage regulator tube D6, and one end of a resistor R27.

Description

Technical Field

[0001] The invention relates to the technical field of fire alarm, in particular to a household combustible gas detector with an exponential curve correction function. Background Art

[0002] Household combustible gas detectors are used in ordinary household kitchens, bathrooms and other places where gas appliances are needed. They can effectively detect the combustible gas content in the environment, prevent explosion accidents caused by gas leaks, and enhance the safety of using gas appliances. However, existing traditional combustible gas detectors are prone to false alarms or large deviations in alarm thresholds due to unreasonable circuit layouts. In addition, communications are easily interfered with, and long-distance communications are very unreliable, which affects the effectiveness of remote fire alarms. Summary of the invention

[0003] In order to solve the existing problems of low detection accuracy and poor communication effect, the present invention provides a household combustible gas detector with an exponential curve correction function, which can improve the detection accuracy and ensure the communication effect.

[0004] The technical solution is as follows: a household combustible gas detector with an exponential curve correction function, which includes a CPU module, characterized in that the CPU module includes a single-chip microcomputer U1, the single-chip microcomputer U1 is electrically connected to a calibration signal processing circuit and a bus communication circuit, the bus communication circuit includes an optical coupler U4, the 1st pin of the optical coupler U4 is connected to a 3.3V power supply, the 2nd pin is connected to the 42nd pin of the single-chip microcomputer U1 through a resistor R37, the 4th pin is connected to a DC+ DC power supply, the 3rd pin is connected to one end of a resistor R30, and the other end of the resistor R30 is connected to a three-pole The base of the transistor Q3 and one end of the resistor R31, the 3rd pin of the transistor Q3 is connected to one end of the resistor R29, the other end of the resistor R29 is connected to one end of the resistor R33, the anode of the diode D9, and the 3rd pin of the common cathode diode D7, the 2nd pin of the common cathode diode D7 is connected to the 1st pin of the common anode diode D8, one end of the capacitor C28, one end of the common cathode voltage regulator D6, and one end of the resistor R27, the 1st pin of the common cathode diode D7 is connected to the 2nd pin of the common anode diode D8, one end of the capacitor C29, one end of the resistor R28, and the other end of the common cathode voltage regulator D6, The other end of the capacitor C28, the other end of the capacitor C29, and the 3rd pin of the common anode diode D8 are connected and then grounded. The cathode of the diode D9 is connected to one end of the capacitor C30, one end of the capacitor C31, and the DC+ DC power supply. One end of the capacitor C30 and the other end of the capacitor C31 are both grounded. The other end of the resistor R33 is connected to one end of the resistor R34, one end of the capacitor C32, one end of the resistor R35, and one end of the capacitor C33. The other end of the capacitor C32 and the other end of the resistor R35 are connected to the base of the transistor Q4. The collector of the transistor Q4 is connected to Connect to the DC+ direct current power supply, the emitter of the transistor Q4 is connected to one end of the capacitor C33 and pin 1 of the optocoupler U5, pin 2 of the optocoupler U5 is connected to one end of the resistor R32, the other end of the resistor R31, the other end of the resistor R32, the other end of the resistor R34, and the emitter of the transistor Q3 are all grounded, pin 4 of the optocoupler U5 is connected to one end of the resistor R36, one end of the capacitor C34, and pin 43 of the microcontroller U1, the other end of the resistor R36 is connected to a 3.3V power supply, and pin 3 of the optocoupler U5 is connected to the other end of the capacitor C34 and then grounded.

[0005] The calibration signal processing circuit includes a methane sensor G1, wherein pin 1 of the methane sensor G1 is connected to a 5V power supply, pin 4 is connected to a source end of a MOS tube Q1 and one end of an inductor L5, pin 3 is connected to one end of a resistor R52 and a drain end of the MOS tube Q1, pin 1 is connected to one end of a capacitor C52 and pin 1 of an operational amplifier U3A, the other end of the resistor R52 is connected to the other end of the capacitor C52 and one end of a resistor R53, the other end of the resistor R53 is connected to pin 2 of the operational amplifier U3A, pin 4 of the operational amplifier U3A is connected to +5V and one end of a capacitor C51, and the operational amplifier The 11th pin of U3A is connected to -5V and one end of capacitor C56, the other end of capacitor C51 and the other end of capacitor C56 are both grounded, the 3rd pin of op amp U3A is connected to one end of resistor R54 and one end of resistor R79, the other end of resistor R79 is connected to one end of resistor R80, the anode of voltage regulator Z51 and one end of resistor R81, the other end of resistor R81 is connected to +5V, the other end of resistor R80 is connected to -5V, the cathode of voltage regulator Z51 is connected to one end of capacitor C61 and grounded, the other end of inductor L55 is connected to one end of resistor R59, The other end of the resistor R59 is connected to one end of the resistor R57, one end of the capacitor C57, and the 6th pin of the operational amplifier U3B. The 5th pin of the operational amplifier U3B is grounded through the resistor R61. The other end of the resistor R57 is connected to one end of the resistor R55 and one end of the adjustable resistor RT1. The other end of the adjustable resistor RT1 is connected to one end of the resistor R56. The other end of the resistor R55 is connected to the other end of the resistor R56 and then connected to one end of the capacitor C57, the 7th pin of the operational amplifier U3B, and one end of the resistor R64. The other end of the resistor R64 is connected to the 10th pin of the operational amplifier U3C, the capacitor C57, and the 7th pin of the operational amplifier U3B. The other end of capacitor C61, pin 9 of the operational amplifier U3C is connected to one end of resistor R63, the other end of the resistor R63 is connected to pin 8 of the operational amplifier U3C, one end of resistor R62, and one end of resistor R85, the other end of the resistor R62 is connected to one end of resistor R82 and pin 13 of the operational amplifier U3D, pin 12 of the operational amplifier U3D is grounded through resistor R83, pin 14 of the operational amplifier U3D is connected to the other end of resistor R82 and one end of resistor R84, the other end of the resistor R85 is connected to the other end of the resistor R84 and then connected to pin 17 of the microcontroller U1.

[0006] After adopting the present invention, the calibration signal processing circuit and the bus communication circuit are reasonably set up, and the bus communication circuit in the form of a current pulling pulse is adopted internally, which effectively solves the communication interference and realizes stable long-distance data communication of not less than 1500 meters. With the cooperation of excellent CPU and software, the linear concentration value and the alarm, fault, and sensor failure status can be accurately uploaded. The information collected by the methane sensor G1 is passed through the operational amplifier and the exponentially changing NTC resistor, and the resistance value of the exponentially changing semiconductor combustible gas sensor is curve corrected, so that the output is a basically linear voltage value signal, and finally processed by the single-chip microcomputer, so that the concentration value of the combustible gas is completely linear, and the detection accuracy is improved to within 2%LEL, which effectively avoids the problem of false alarm or large deviation of the alarm threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The CPU module schematic diagram of the present invention;

[0008] Figure 2 This is the schematic diagram of the bus communication circuit;

[0009] Figure 3 This is the schematic diagram of the calibration signal processing circuit;

[0010] Figure 4 It is a control flow diagram. DETAILED DESCRIPTION

[0011] See Figures 1 to 4As shown, a household combustible gas detector with an exponential curve correction function includes a CPU module, the CPU module includes a single-chip microcomputer U1, the single-chip microcomputer U1 is electrically connected to a calibration signal processing circuit and a bus communication circuit, the bus communication circuit includes an optocoupler U4, pin 1 of the optocoupler U4 is connected to a 3.3V power supply, pin 2 is connected to pin 42 of the single-chip microcomputer U1 through a resistor R37, pin 4 is connected to a DC+ DC power supply, pin 3 is connected to one end of a resistor R30, the other end of the resistor R30 is connected to the base of a transistor Q3 and one end of a resistor R31, pin 3 of the transistor Q3 is connected to one end of a resistor R29, and the other end of the resistor R30 is connected to the base of a transistor Q3 and one end of a resistor R31, pin 3 of the transistor Q3 is connected to one end of a resistor R29, and the optocoupler U4 is electrically connected to a 3.3V power supply, pin 2 is connected to pin 42 of the single-chip microcomputer U1 through a resistor R37, pin 4 is connected to a DC+ DC power supply, pin 3 is connected to one end of a resistor R30 ... optocoupler U4 is electrically connected to a 3.3V power supply, pin 2 is connected to pin 42 of the single-chip microcomputer U1 through a resistor R37, pin 4 is connected to a DC+ DC power supply, pin The other end of resistor R29 is connected to one end of resistor R33, the anode of diode D9, the 3rd pin of common cathode diode D7, the 2nd pin of common cathode diode D7 is connected to the 1st pin of common anode diode D8, one end of capacitor C28, one end of common cathode voltage regulator D6, one end of resistor R27, the 1st pin of common cathode diode D7 is connected to the 2nd pin of common anode diode D8, one end of capacitor C29, one end of resistor R28, the other end of common cathode voltage regulator D6, the other end of capacitor C28, the other end of capacitor C29, and the common The 3rd pin of the anode diode D8 is connected and then grounded, the cathode of the diode D9 is connected to one end of the capacitor C30, one end of the capacitor C31, and the DC+ power supply, one end of the capacitor C30 and the other end of the capacitor C31 are both grounded, the other end of the resistor R33 is connected to one end of the resistor R34, one end of the capacitor C32, one end of the resistor R35, and one end of the capacitor C33, the other end of the capacitor C32 and the other end of the resistor R35 are connected to the base of the transistor Q4, and the collector of the transistor Q4 is connected to the DC+ power supply. The emitter of transistor Q4 is connected to one end of capacitor C33 and pin 1 of optocoupler U5, pin 2 of optocoupler U5 is connected to one end of resistor R32, the other end of resistor R31, the other end of resistor R32, the other end of resistor R34, and the emitter of transistor Q3 are all grounded, pin 4 of optocoupler U5 is connected to one end of resistor R36, one end of capacitor C34, and pin 43 of microcontroller U1, the other end of resistor R36 is connected to a 3.3V power supply, and pin 3 of optocoupler U5 is connected to the other end of capacitor C34 and then grounded.

[0012] The calibration signal processing circuit includes a methane sensor G1, wherein pin 1 of the methane sensor G1 is connected to a 5V power supply, pin 4 is connected to the source end of the MOS tube Q1 and one end of the inductor L5, pin 3 is connected to one end of the resistor R52 and the drain end of the MOS tube Q1, pin 1 is connected to one end of the capacitor C52 and pin 1 of the operational amplifier U3A, the other end of the resistor R52 is connected to the other end of the capacitor C52 and one end of the resistor R53, the other end of the resistor R53 is connected to pin 2 of the operational amplifier U3A, pin 4 of the operational amplifier U3A is connected to +5V and one end of the capacitor C51, and the operational amplifier Pin 11 of U3A is connected to -5V and one end of capacitor C56, the other end of capacitor C51 and the other end of capacitor C56 are both grounded, pin 3 of op amp U3A is connected to one end of resistor R54 and one end of resistor R79, the other end of resistor R79 is connected to one end of resistor R80, the anode of voltage regulator Z51, and one end of resistor R81, the other end of resistor R81 is connected to +5V, the other end of resistor R80 is connected to -5V, the cathode of voltage regulator Z51 is connected to one end of capacitor C61 and grounded, the other end of inductor L55 is connected to resistor R59. The other end of resistor R59 is connected to one end of resistor R57, one end of capacitor C57, and pin 6 of op amp U3B. Pin 5 of op amp U3B is grounded through resistor R61. The other end of resistor R57 is connected to one end of resistor R55 and one end of adjustable resistor RT1. The other end of adjustable resistor RT1 is connected to one end of resistor R56. The other end of resistor R55 and the other end of resistor R56 are connected and then connected to one end of capacitor C57, pin 7 of op amp U3B, and one end of resistor R64. The other end of resistor R64 is connected to pin 10 of op amp U3C. , the other end of capacitor C61, pin 9 of op amp U3C is connected to one end of resistor R63, the other end of resistor R63 is connected to pin 8 of op amp U3C, one end of resistor R62, and one end of resistor R85, the other end of resistor R62 is connected to one end of resistor R82 and pin 13 of op amp U3D, pin 12 of op amp U3D is grounded through resistor R83, pin 14 of op amp U3D is connected to the other end of resistor R82 and one end of resistor R84, the other end of resistor R85 is connected to the other end of resistor R84 and then connected to pin 17 of microcontroller U1.

[0013] The present invention is composed of a methane sensor, an exponential curve calibration signal processing circuit, a high-performance AD ​​conversion CPU, a bus communication circuit, an alarm actuator, a power supply, etc. The exponential curve calibration signal processing circuit combined with the high-performance AD ​​conversion CPU can convert the resistance value of the combustible gas sensor with exponential curve changes into a voltage and concentration value of a linear concentration. The bus communication circuit can achieve extremely strong anti-interference and long-distance transmission of concentration values ​​and various information to a fire alarm controller or a combustible gas alarm controller, realize on-site alarm and remote centralized monitoring of combustible gas leaks, improve the detection and alarm capabilities of gas leaks, effectively prevent explosion accidents caused by gas leaks, enhance the safety of using gas appliances, and improve the detection accuracy to within 2%LEL, effectively avoiding the problem of false alarms or large deviations in alarm thresholds.

Claims

1. A household combustible gas detector with exponential curve correction function, comprising a CPU module, characterized in that: The CPU module includes a single-chip microcomputer U1, and the single-chip microcomputer U1 is electrically connected to a calibration signal processing circuit and a bus communication circuit. The bus communication circuit includes an optocoupler U4, and pin 1 of the optocoupler U4 is connected to a 3.3V power supply, pin 2 is connected to pin 42 of the single-chip microcomputer U1 through a resistor R37, pin 4 is connected to a DC+ DC power supply, and pin 3 is connected to one end of a resistor R30. The other end of the resistor R30 is connected to the base of a transistor Q3 and one end of a resistor R31. Pin 3 of the transistor Q3 is connected to one end of a resistor R29. The other end of the resistor R29 is connected to one end of the resistor R33, the anode of the diode D9, and the 3rd pin of the common cathode diode D7. The 2nd pin of the common cathode diode D7 is connected to the 1st pin of the common anode diode D8, one end of the capacitor C28, one end of the common cathode voltage regulator D6, and one end of the resistor R27. The 1st pin of the common cathode diode D7 is connected to the 2nd pin of the common anode diode D8, one end of the capacitor C29, one end of the resistor R28, and the other end of the common cathode voltage regulator D6. The other end of the capacitor C28, the other end of the capacitor C29, and the common anode diode The 3rd pin of the transistor D8 is connected and then grounded, the cathode of the diode D9 is connected to one end of the capacitor C30, one end of the capacitor C31, and the DC+ direct current power supply, one end of the capacitor C30 and the other end of the capacitor C31 are both grounded, the other end of the resistor R33 is connected to one end of the resistor R34, one end of the capacitor C32, one end of the resistor R35, and one end of the capacitor C33, the other end of the capacitor C32 and the other end of the resistor R35 are connected to the base of the transistor Q4, and the collector of the transistor Q4 is connected to the DC+ direct current power supply, The emitter of the transistor Q4 is connected to one end of the capacitor C33 and pin 1 of the optocoupler U5, pin 2 of the optocoupler U5 is connected to one end of the resistor R32, the other end of the resistor R31, the other end of the resistor R32, the other end of the resistor R34, and the emitter of the transistor Q3 are all grounded, pin 4 of the optocoupler U5 is connected to one end of the resistor R36, one end of the capacitor C34, and pin 43 of the microcontroller U1, the other end of the resistor R36 is connected to a 3.3V power supply, and pin 3 of the optocoupler U5 is connected to the other end of the capacitor C34 and then grounded.

2. A household combustible gas detector with exponential curve correction function according to claim 1, characterized in that: The calibration signal processing circuit includes a methane sensor G1, wherein pin 1 of the methane sensor G1 is connected to a 5V power supply, pin 4 is connected to a source end of a MOS tube Q1 and one end of an inductor L5, pin 3 is connected to one end of a resistor R52 and a drain end of the MOS tube Q1, pin 1 is connected to one end of a capacitor C52 and pin 1 of an operational amplifier U3A, the other end of the resistor R52 is connected to the other end of the capacitor C52 and one end of a resistor R53, the other end of the resistor R53 is connected to pin 2 of the operational amplifier U3A, pin 4 of the operational amplifier U3A is connected to +5V and one end of a capacitor C51, and the operational amplifier The 11th pin of U3A is connected to -5V and one end of capacitor C56, the other end of capacitor C51 and the other end of capacitor C56 are both grounded, the 3rd pin of op amp U3A is connected to one end of resistor R54 and one end of resistor R79, the other end of resistor R79 is connected to one end of resistor R80, the anode of voltage regulator Z51 and one end of resistor R81, the other end of resistor R81 is connected to +5V, the other end of resistor R80 is connected to -5V, the cathode of voltage regulator Z51 is connected to one end of capacitor C61 and grounded, the other end of inductor L55 is connected to one end of resistor R59, The other end of the resistor R59 is connected to one end of the resistor R57, one end of the capacitor C57, and the 6th pin of the operational amplifier U3B. The 5th pin of the operational amplifier U3B is grounded through the resistor R61. The other end of the resistor R57 is connected to one end of the resistor R55 and one end of the adjustable resistor RT1. The other end of the adjustable resistor RT1 is connected to one end of the resistor R56. The other end of the resistor R55 is connected to the other end of the resistor R56 and then connected to one end of the capacitor C57, the 7th pin of the operational amplifier U3B, and one end of the resistor R64. The other end of the resistor R64 is connected to the 10th pin of the operational amplifier U3C, the capacitor C57, and the 7th pin of the operational amplifier U3B. The other end of capacitor C61, pin 9 of the operational amplifier U3C is connected to one end of resistor R63, the other end of the resistor R63 is connected to pin 8 of the operational amplifier U3C, one end of resistor R62, and one end of resistor R85, the other end of the resistor R62 is connected to one end of resistor R82 and pin 13 of the operational amplifier U3D, pin 12 of the operational amplifier U3D is grounded through resistor R83, pin 14 of the operational amplifier U3D is connected to the other end of resistor R82 and one end of resistor R84, the other end of the resistor R85 is connected to the other end of the resistor R84 and then connected to pin 17 of the microcontroller U1.

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