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CN-121994880-A - Thermal conductance type gas detection device

CN121994880ACN 121994880 ACN121994880 ACN 121994880ACN-121994880-A

Abstract

The application provides a thermal conductance type gas detection device. Since the output voltage of the feedback tracking module at the initial moment is equal to the output voltage of the voltage stabilizing source and the resistance values of the two heating resistors are equal, the temperatures of the two chambers at the initial moment are equal. If the gas with poor heat conductivity is mixed, the temperature of the detection cavity is increased, the resistance value of the second NTC thermistor is reduced, so that the output voltage of the feedback tracking module is reduced, the heating power of the second heating resistor is reduced, the temperature of the detection cavity is reduced, and the temperature of the two cavities is equal finally through circulation. From the above, the concentration of the gas mixed into the detection chamber can be detected by using the variation of the output voltage of the feedback tracking module. The temperature of the final detection cavity is the same as that of the reference cavity, so that the working temperatures of the final two NTC thermistors are the same, and the heating values are nearly the same, so that the difference between the deviations of the resistance values of the two NTC thermistors is reduced, and the detection precision of the thermal conductivity type gas detection device is improved.

Inventors

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Assignees

  • 杭州三花研究院有限公司

Dates

Publication Date
20260508
Application Date
20241031

Claims (10)

  1. 1. The heat conduction type gas detection device is characterized by comprising a voltage stabilizing source, a first module, a feedback tracking module, a first heating resistor and a second heating resistor, wherein: The first module includes a first NTC thermistor and a second NTC thermistor; the first heating resistor is arranged in the reference cavity, one end of the first heating resistor is connected with the output end of the voltage stabilizing source, the other end of the first heating resistor is grounded, and the first NTC thermistor is arranged in the reference cavity; the second heating resistor is arranged in the detection cavity, one end of the second heating resistor is connected with the output end of the feedback tracking module, the other end of the second heating resistor is grounded, and the second NTC thermistor is arranged in the detection cavity; The resistance of the first heating resistor is equal to that of the second heating resistor, and the output end of the first module is connected with the input end of the feedback tracking module; the feedback tracking module is capable of outputting a variable voltage.
  2. 2. The device of claim 1, wherein the first module comprises a first output and a second output, the feedback tracking module comprises a first input and a second input, the first output of the first module is connected to the first input of the feedback tracking module, and the second output of the first module is connected to the second input of the feedback tracking module; The first output end of the first module is grounded, the second output end of the first module is connected with the serial end of the second NTC thermistor, the other end of the first NTC thermistor is connected with the output end of the voltage stabilizing source, and the other end of the second NTC thermistor is grounded.
  3. 3. The device of claim 1, wherein the first module comprises a first resistor and a second resistor, wherein the first resistor and the second resistor have equal resistance values, wherein the first module comprises a first output end and a second output end, wherein the feedback tracking module comprises a first input end and a second input end, wherein the first output end of the first module is connected with the first input end of the feedback tracking module, and wherein the second output end of the first module is connected with the second input end of the feedback tracking module; the first resistor is connected in series with the second resistor, the serial end of the second resistor is a first output end of the first module, the other end of the first resistor is connected with the output end of the voltage stabilizing source, the other end of the second resistor is grounded, the first NTC thermistor and the second NTC thermistor are connected in series, the serial end of the second NTC thermistor is a second output end of the first module, the other end of the first NTC thermistor is connected with the output end of the voltage stabilizing source, and the other end of the second NTC thermistor is grounded; Or the first resistor is connected with the first NTC thermistor in series, the serial end of the first NTC thermistor is a first output end of the first module, the other end of the first resistor is connected with the output end of the voltage stabilizing source, the other end of the first NTC thermistor is grounded, the second resistor is connected with the second NTC thermistor in series, the serial end of the second NTC thermistor is a second output end of the first module, the other end of the second resistor is connected with the output end of the voltage stabilizing source, and the other end of the second NTC thermistor is grounded.
  4. 4. A thermally conductive gas-detecting apparatus as defined in claim 3, wherein said thermally conductive gas-detecting apparatus comprises an input power circuit, and said feedback tracking module comprises a differential proportional-operating circuit and a first transistor, wherein: the non-inverting input end of the differential proportion operation circuit is used as the first input end of the feedback tracking module, and the inverting input end of the differential proportion operation circuit is used as the second input end of the feedback tracking module; The output end of the differential proportion operation circuit is connected with the base electrode of the first triode, the collector electrode of the first triode is connected with the output end of the input power supply circuit, and the emitter electrode of the first triode is used as the output end of the feedback tracking module; the potential of the output end of the differential proportion operation circuit at the initial moment is equal to the output voltage of the voltage stabilizing source plus the voltage difference between the base electrode and the emitter electrode of the first triode.
  5. 5. The apparatus according to claim 4, wherein the differential proportional operation circuit comprises a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and an operational amplifier, wherein: The non-inverting input end of the operational amplifier is connected with one end of the third resistor, and the other end of the third resistor is used as the non-inverting input end of the differential proportion operation circuit; the non-inverting input end of the operational amplifier is also connected with one end of the fourth resistor, the potential of the other end of the fourth resistor is equal to the output voltage of the voltage stabilizing source, and the other end of the fourth resistor is connected with the output end of the input power supply circuit; The inverting input end of the operational amplifier is connected with one end of the fifth resistor, and the other end of the fifth resistor is used as the inverting input end of the differential proportion operational circuit; The inverting input end of the operational amplifier is also connected with one end of the sixth resistor, and the other end of the sixth resistor is connected with the output end of the operational amplifier; The output end of the operational amplifier is used as the output end of the differential proportion operational circuit.
  6. 6. The apparatus according to any one of claims 1 to 5, wherein a ratio of a resistance value of the first heating resistor to a resistance value of the first NTC thermistor is 10 3 or more, and/or a ratio of a resistance value of the second heating resistor to a resistance value of the second NTC thermistor is 10 3 or more; the voltage stabilizing source comprises a first voltage stabilizer, a seventh resistor and an eighth resistor; The anode of the first voltage stabilizer is grounded, and the cathode of the first voltage stabilizer is used as the output end of the voltage stabilizing source; one end of the seventh resistor is connected with the control end of the first voltage stabilizer, one end of the eighth resistor is connected with the control end of the first voltage stabilizer, and the seventh resistor is connected with the eighth resistor in series; the other end of the seventh resistor is connected with the anode of the first voltage stabilizer, and the other end of the eighth resistor is connected with the cathode of the first voltage stabilizer.
  7. 7. The apparatus of any one of claims 1-5, comprising an input power circuit, wherein the voltage regulator source comprises a second triode, a second voltage regulator, a first resistive branch, and a second resistive branch, wherein: The anode of the second voltage stabilizer is grounded, the cathode of the second voltage stabilizer is connected with the base electrode of the second triode, the collector electrode of the second triode is connected with the output end of the input power supply circuit, and the emitter of the second triode is used as the output end of the voltage stabilizing source; the second triode is an N-type triode; the control end of the second voltage stabilizer is connected with one end of the first resistance branch, and the control end of the second voltage stabilizer is connected with one end of the second resistance branch; the other end of the first resistor branch is connected with the anode of the second voltage stabilizer, and the other end of the second resistor branch is connected with the emitter of the second triode.
  8. 8. The thermally conductive gas detecting apparatus as defined in claim 7, wherein in at least one of the resistive branches, each of the resistive branches comprises at least two ninth resistors and at least one switching tube; The series ends of any two ninth resistors are connected with the input ends of the corresponding switching tubes, the output ends of each switching tube are grounded, and all the switching tubes are controlled to be switched on and off; Or alternatively Each resistor branch comprises a tenth resistor, and two ends of the tenth resistor are respectively used as two ends of the resistor branch.
  9. 9. The thermally conductive gas-detecting apparatus of any one of claims 1 to 5, further comprising a first thermally conductive member disposed in the reference chamber and a second thermally conductive member disposed in the detection chamber, wherein: the first NTC thermistor and the first heating resistor are connected with the first heat conduction piece; The second NTC thermistor and the second heating resistor are connected with the second heat conduction piece.
  10. 10. The heat conduction type gas detection device is characterized by comprising a voltage stabilizing source, a first module, a feedback tracking module, a first heating resistor and a second heating resistor, wherein: The first module includes a first NTC thermistor and a second NTC thermistor; the first heating resistor is arranged in the reference cavity, one end of the first heating resistor is connected with the output end of the voltage stabilizing source, the other end of the first heating resistor is grounded, and the first NTC thermistor is arranged in the reference cavity; the second heating resistor is arranged in the detection cavity, one end of the second heating resistor is connected with the output end of the feedback tracking module, the other end of the second heating resistor is grounded, and the second NTC thermistor is arranged in the detection cavity; The resistance of the first heating resistor is equal to that of the second heating resistor, and the output end of the first module is connected with the feedback tracking module; The output end of the first module can be used for obtaining the ratio of the voltage at two ends of the second NTC thermistor to the voltage at two ends of the first NTC thermistor, the ratio of the voltage at two ends of the second NTC thermistor to the voltage at two ends of the first NTC thermistor at the initial moment is defined as X, the voltage value output by the feedback tracking module at the initial moment is equal to the output voltage value of the voltage stabilizing source, and the feedback tracking module can be used for enabling the output voltage of the feedback tracking module to change correspondingly under the condition that the ratio of the voltage at two ends of the second NTC thermistor to the voltage at two ends of the first NTC thermistor changes compared with the ratio X at the initial moment.

Description

Thermal conductance type gas detection device Technical Field The invention relates to the technical field of measurement, in particular to a thermal conductivity type gas detection device. Background The thermal conductivity type gas detection device is a device for detecting whether or not a gas having different thermal conductivities and the concentration of the mixed gas are mixed in an environment, and has advantages not possessed by many gas sensors, such as a large detection range, high reliability, simple device, low price, convenient maintenance, and the like. The thermally conductive gas detection device includes a detection chamber and a reference chamber, typically with an NTC thermistor for temperature measurement. When the detection cavity in the thermal conductivity type gas detection device mixes with gases with different concentrations, the temperature of the detection cavity changes compared with the reference cavity, so that the resistance value of the NTC thermistor in the detection cavity changes compared with the NTC thermistor in the reference cavity, and the concentration of the mixed gases can be detected according to the resistance value difference of the two NTC thermistors. When the temperature of the two cavities is different when the detection cavities are mixed with gases with different concentrations, the working temperatures of the two NTC thermistors are different, so that the resistance of the two NTC thermistors is deviated from the resistance corresponding to the actual temperature to be detected, the detection precision of the thermal conductivity type gas detection device is low, and the thermal conductivity type gas detection device cannot be applied to scenes with high precision requirements. Therefore, how to improve the detection accuracy of the thermal conductivity type gas detection device is a technical problem to be solved. Disclosure of Invention In view of the above, the present invention provides a thermal conductivity type gas detecting device to improve the detecting precision of the thermal conductivity type gas detecting device. In order to achieve the above purpose, the following technical scheme is provided: A thermal conductance type gas detection device comprises a voltage stabilizing source, a first module, a feedback tracking module, a first heating resistor and a second heating resistor, wherein: The first module includes a first NTC thermistor and a second NTC thermistor; the first heating resistor is arranged in the reference cavity, one end of the first heating resistor is connected with the output end of the voltage stabilizing source, the other end of the first heating resistor is grounded, and the first NTC thermistor is arranged in the reference cavity; the second heating resistor is arranged in the detection cavity, one end of the second heating resistor is connected with the output end of the feedback tracking module, the other end of the second heating resistor is grounded, and the second NTC thermistor is arranged in the detection cavity; The resistance of the first heating resistor is equal to that of the second heating resistor, and the output end of the first module is connected with the input end of the feedback tracking module; the feedback tracking module is capable of outputting a variable voltage. In the technical scheme, the voltage at two ends of the first heating resistor is equal to the output voltage of the voltage stabilizing source, the feedback tracking module can output variable voltage, when the voltage value which can be output by the feedback tracking module is equal to the output voltage of the voltage stabilizing source, the heating power of the first heating resistor is identical to that of the second heating resistor, the temperatures collected by the first heating resistor and the second heating resistor are identical, under a certain fixed heat dissipation condition under standard atmosphere, other influencing factors are eliminated, the temperature of the detection cavity and the reference cavity is determined only by the heating power of the first heating resistor and the second heating resistor, the temperature of the detection cavity is identical to that of the reference cavity, therefore, the resistance value of the first NTC thermistor and the resistance value of the second NTC thermistor are identical, when mixed with gases with different heat conductivities, the temperature difference exists between the detection cavity and the reference cavity, the temperature difference between the two heat conducting power of the first NTC thermistor and the second NTC thermistor is reduced, the temperature difference between the two heat conducting cavities is reduced, and the temperature difference between the two heat conducting devices is reduced. The application also provides a thermal conductance type gas detection device, which comprises a voltage stabilizing source, a first module, a feedback tracking module,