CN219533071U - Gas concentration detection device - Google Patents
Gas concentration detection device Download PDFInfo
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- CN219533071U CN219533071U CN202320270949.8U CN202320270949U CN219533071U CN 219533071 U CN219533071 U CN 219533071U CN 202320270949 U CN202320270949 U CN 202320270949U CN 219533071 U CN219533071 U CN 219533071U
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Abstract
The present utility model relates to a gas concentration detection apparatus. The device comprises a voltage stabilizing module, a sensing amplifying module, a digital-to-analog conversion module and a temperature sensing module; the voltage stabilizing module outputs a voltage signal to the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module; the sensing amplification module detects the gas concentration and outputs an amplified gas concentration detection signal to the digital-to-analog conversion module; the temperature sensing module detects the ambient temperature and outputs a temperature detection signal to the digital-to-analog conversion module; the digital-to-analog conversion module converts the amplified gas concentration detection signal and the temperature detection signal into analog signals and outputs the analog signals. Accurate gas concentration detection can be supported.
Description
Technical Field
The utility model relates to the technical field of circuits, in particular to a gas concentration detection device.
Background
The influence of the gas in the surrounding environment on the health of the human body is of great importance. Taking formaldehyde gas as an example, formaldehyde is a "top-grade killer" polluted by indoor air, and is listed as a class I cancerogenic substance by the world health organization in 2017, if people live or work in an environment with excessive formaldehyde for a long time, the physical and mental health of individuals can be seriously affected, and a plurality of malignant diseases of tissues and organs such as respiratory tract, lung, blood and the like are easily induced. In order to better ensure the health of human bodies, a technology for detecting the content of gas in the surrounding environment has been developed.
Generally, a device for detecting the gas content in the environment may be a semiconductor sensor, an optical sensor, etc., but in practical application, the gas concentration detection environment is complex, and the conventional gas concentration detection device does not support accurate gas concentration detection.
Disclosure of Invention
In view of the above, it is desirable to provide a gas concentration detection apparatus that supports accurate gas concentration detection.
The utility model provides a gas concentration detection device. The device comprises a voltage stabilizing module, a sensing amplifying module, a digital-to-analog conversion module and a temperature sensing module;
the voltage stabilizing module outputs a voltage signal to the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module; the sensing amplification module detects the gas concentration and outputs an amplified gas concentration detection signal to the digital-to-analog conversion module; the temperature sensing module detects the ambient temperature and outputs a temperature detection signal to the digital-to-analog conversion module; the digital-to-analog conversion module converts the amplified gas concentration detection signal and the temperature detection signal into analog signals and outputs the analog signals.
In one embodiment, the voltage stabilizing module comprises a linear voltage stabilizer and a first capacitor;
the input end of the linear voltage stabilizer is connected with an external voltage signal, the output end of the linear voltage stabilizer is respectively connected with one end of the first capacitor, the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module, and the other end of the first capacitor is grounded.
In one embodiment, the device further comprises a voltage dividing module;
the voltage division module comprises a first resistor and a second resistor; one end of the first resistor is connected with the voltage stabilizing module, the other end of the first resistor is connected with the sensing amplifying module and one end of the second resistor, and the other end of the second resistor is grounded.
In one embodiment, the sense amplifier module includes a first operational amplifier assembly, a sensor assembly, and a second operational amplifier assembly;
the positive input end of the first operational amplification component is connected with the first resistor, the negative input end of the first operational amplification component is connected with the output end of the first operational amplification component, and the output end of the first operational amplification component is connected with the positive input end of the second operational amplification component and the positive electrode of the sensor component; the inverting input end of the second operational amplification assembly is connected with the negative electrode of the sensor assembly, and the output end of the second operational amplification assembly is connected with the digital-to-analog conversion module.
In one embodiment, the sensor assembly includes a gas sensor and a third resistor;
one end of the third resistor is connected with the positive electrode of the gas sensor, and the other end of the third resistor is connected with the negative electrode of the gas sensor;
the gas sensor detects the gas concentration and outputs a gas concentration signal to the second operational amplification component.
In one embodiment, the second operational amplifier component includes an operational amplifier, a negative feedback component, and a second capacitor.
The operational amplifier is connected with the voltage stabilizing module, the positive input end of the operational amplifier is connected with the positive electrode of the sensor assembly, the negative input end of the operational amplifier is connected with the negative electrode of the sensor assembly, and the output end of the operational amplifier is connected with the digital-to-analog conversion module; one end of the negative feedback component is connected with the inverting input end of the operational amplifier, and the other end of the negative feedback component is connected with the output end of the operational amplifier; the second capacitor is connected in parallel with the negative feedback component.
In one embodiment, the negative feedback component comprises a fourth negative feedback resistor and a fifth negative feedback resistor;
one end of the fourth negative feedback resistor is connected with the inverting input end of the operational amplifier, and the other end of the fourth negative feedback resistor is connected with one end of the fifth negative feedback resistor; and the other end of the fifth negative feedback resistor is connected with the output end of the operational amplifier.
In one embodiment, the filter further comprises an RC (resistor capacitor, resistor and capacitor) filter module;
the RC filter module comprises a sixth resistor and a third capacitor; one end of the sixth resistor is connected with the sensing amplification module, and the other end of the sixth resistor is connected with the digital-to-analog conversion module and one end of the third capacitor; the other end of the third capacitor is grounded.
In one embodiment, the digital-to-analog conversion module includes an MCU (Microcontroller Unit, micro control unit) chip, a fourth capacitor, a fifth capacitor, a sixth capacitor, and a seventh resistor;
the MCU chip is respectively connected with the temperature sensing module, one end of the fifth capacitor and two ends of the fourth capacitor; one end of the fourth capacitor is connected with the voltage stabilizing module, and the other end of the fourth capacitor is grounded; the other end of the fifth capacitor is connected with one end of the sixth capacitor and grounded; the other end of the sixth capacitor is connected with one end of the seventh resistor; the other end of the seventh resistor is connected with the voltage stabilizing module.
In one embodiment, the temperature sensing module includes an NTC (Negative Temperature Coefficient ) resistor and an eighth resistor;
one end of the NTC resistor is connected with the digital-to-analog conversion module and one end of the eighth resistor, and the other end of the NTC resistor is connected with the voltage stabilizing module; the other end of the eighth resistor is grounded.
The gas detection device comprises a voltage stabilizing module, a sensing amplifying module, a digital-to-analog conversion module and a temperature sensing module; the voltage stabilizing module outputs a voltage signal to the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module; the sensing amplification module detects the gas concentration and outputs an amplified gas concentration detection signal to the digital-to-analog conversion module; the temperature sensing module detects the ambient temperature and outputs a temperature detection signal to the digital-to-analog conversion module; the digital-to-analog conversion module converts the amplified gas concentration detection signal and the temperature detection signal into analog signals and outputs the analog signals. In the utility model, the voltage stabilizing module can output stable voltage to the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module, and because the concentration of the gas signal collected by the sensor in the surrounding environment is low, the amplified gas concentration detection signal can be output based on the sensing amplifying module for further analysis; in addition, the digital-to-analog conversion module can also be used for receiving the amplified gas concentration detection signal and converting the temperature detection signal into an analog signal and outputting the analog signal based on the current environmental temperature perceived by the temperature sensing module, and the digital-to-analog conversion module is used for laying a cushion for correcting the gas concentration detection signal at the current temperature so as to support accurate detection of the gas concentration at different environmental temperatures.
Drawings
FIG. 1 is a schematic diagram showing a structure of a gas concentration detecting apparatus according to an embodiment;
FIG. 2 is a schematic diagram of a voltage stabilizing module according to an embodiment;
FIG. 3 is a schematic diagram of a gas sensor in one embodiment;
FIG. 4 is a schematic diagram of a digital-to-analog conversion module in one embodiment;
fig. 5 is a schematic circuit diagram of a gas concentration detection apparatus in one embodiment.
Detailed Description
The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.
In order to explain the constituent structure of the gas concentration detecting apparatus of the present utility model and the functions thereof in detail, description will be made below in the embodiments.
In one embodiment, as shown in fig. 1, a gas concentration detection apparatus is provided, the apparatus includes a voltage stabilizing module 200, a sense amplifying module 400, a digital-to-analog conversion module 600, and a temperature sensing module 800;
the voltage stabilizing module 200 outputs a voltage signal to the sensing amplifying module 400, the digital-to-analog conversion module 600 and the temperature sensing module 800; the sensing amplification module 400 detects the gas concentration and outputs an amplified gas concentration detection signal to the digital-to-analog conversion module 600; the temperature sensing module 800 detects the ambient temperature and outputs a temperature detection signal to the digital-to-analog conversion module 600; the digital-to-analog conversion module 600 converts the amplified gas concentration detection signal and the temperature detection signal into analog signals and outputs the analog signals.
The voltage stabilizing module is a module capable of reducing the voltage of an external input voltage signal so as to obtain a stable voltage signal, and can be used as a power module to provide stable voltage for the subsequent module to work; the digital-to-analog conversion module is used for performing the mutual conversion between the digital signal and the analog signal; the temperature sensing module refers to a module capable of detecting an ambient temperature.
Specifically, taking an external voltage signal +5v as an example, inputting +5v to the voltage stabilizing module 200, reducing the voltage by the voltage stabilizing module 200 to obtain a stable voltage signal +3v, and outputting a power supply voltage to the sensing amplifying module 400, the digital-to-analog conversion module 600 and the temperature sensing module 800; because the gas concentration signal collected by the common gas sensor in the surrounding environment is low, the sensor amplification module 400 is adopted to detect the gas concentration and amplify the gas concentration, and the amplified gas concentration detection signal is output; the amplified gas concentration detection signal is obtained at this time, and the current ambient temperature is also required to be sensed, so the temperature sensing module 800 is set to detect the ambient temperature, and the temperature detection signal is output to the digital-to-analog conversion module 600; and because the temperature detection signal and the amplified gas concentration detection signal are used to support the accurate detection of the gas concentration at different ambient temperatures, the sensor amplification module 400 is required to output the amplified gas concentration detection signal to the digital-to-analog conversion module 600, the temperature sensing module 800 outputs the temperature detection signal to the digital-to-analog conversion module 600, and the digital-to-analog conversion module 600 converts the signals into analog signals for output, so as to support the further accurate detection of the gas concentration at different ambient temperatures.
The gas detection device comprises a voltage stabilizing module, a sensing amplifying module, a digital-to-analog conversion module and a temperature sensing module; the voltage stabilizing module outputs a voltage signal to the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module; the sensing amplification module detects the gas concentration and outputs an amplified gas concentration detection signal to the digital-to-analog conversion module; the temperature sensing module detects the ambient temperature and outputs a temperature detection signal to the digital-to-analog conversion module; the digital-to-analog conversion module converts the amplified gas concentration detection signal and the temperature detection signal into analog signals and outputs the analog signals. In the utility model, the voltage stabilizing module can output stable voltage to the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module, and because the concentration of the gas signal collected by the sensor in the surrounding environment is low, the amplified gas concentration detection signal can be output based on the sensing amplifying module for further analysis; in addition, the digital-to-analog conversion module can also be used for receiving the amplified gas concentration detection signal and converting the temperature detection signal into an analog signal and outputting the analog signal based on the current environmental temperature perceived by the temperature sensing module, and the digital-to-analog conversion module is used for laying a cushion for correcting the gas concentration detection signal at the current temperature so as to support accurate detection of the gas concentration at different environmental temperatures.
In one embodiment, as shown in fig. 2, the voltage stabilizing module includes a linear voltage stabilizer U1 and a first capacitor C1;
the input end of the linear voltage stabilizer U1 is connected with an external voltage signal, the output end of the linear voltage stabilizer U1 is respectively connected with one end of the first capacitor C1, the sensing amplification module, the digital-to-analog conversion module and the temperature sensing module, and the other end of the first capacitor C1 is grounded.
The linear voltage stabilizer is a key element in the voltage stabilizing module, uses a transistor operating in a linear region of the linear voltage stabilizer to subtract excess voltage from applied input voltage to generate regulated output voltage, and has high efficiency, low quiescent current and high ripple rejection; the first capacitor is a capacitor for improving frequency stability of the linear voltage regulator and preventing output oscillation of the linear voltage regulator, and may have a specification of 10uF.
As shown in fig. 2, the linear voltage regulator U1 has five pins, pin 1 is an input end of the linear voltage regulator U1, pin 2 is grounded, pin 3 is one pin that needs to be used by the linear voltage regulator U1 when reading and writing, pin 4 is an empty pin, pin 5 is an output end of the linear voltage regulator U1, pin 1 and pin 3 are connected with an external voltage signal +5v, the external voltage signal +5v is reduced by the inside of the linear voltage regulator U1 and then is output from pin 5 to +3v, and since the output end of the linear voltage regulator U1 is respectively connected with the sensing amplifying module, the digital-analog conversion module and the temperature sensing module, the voltage signal +3v can be input into the sensing amplifying module, the digital-analog conversion module and the temperature sensing module to provide stable voltages for the modules; in order to improve the frequency stability of the linear voltage stabilizer U1 and prevent the output oscillation of the linear voltage stabilizer U1, the voltage stabilizing module is further provided with a first capacitor C1, one end of the first capacitor C1 is connected with the output end of the linear voltage stabilizer U1, and the other end of the first capacitor C1 is grounded.
In this embodiment, the linear voltage regulator in the voltage stabilizing module may output the external voltage signal as a stable voltage signal, so as to provide a stable voltage for a subsequent module, and the setting of the first capacitor makes the frequency stability of the linear voltage regulator improved, so that the output oscillation of the linear voltage regulator is avoided.
In one embodiment, the device further comprises a voltage dividing module;
the voltage dividing module comprises a first resistor and a second resistor; one end of the first resistor is connected with the voltage stabilizing module, the other end of the first resistor is connected with the sensing amplifying module and one end of the second resistor, and the other end of the second resistor is grounded.
The voltage dividing module in the utility model is a module for dividing an input voltage signal by using two resistors.
Specifically, the voltage dividing module comprises a first resistor and a second resistor, the first resistor and the second resistor are 1% high-precision resistors, one end of the first resistor is connected with the voltage stabilizing module, so that an output voltage signal from the voltage stabilizing module can be input into the first resistor at first, the other end of the first resistor is connected with the sensing amplifying module and one end of the second resistor, the other end of the second resistor is grounded, the voltage of the output voltage signal from the voltage stabilizing module can be divided by the first resistor and the second resistor, and the voltage dividing point of the first resistor and the second resistor, namely, the other end of the first resistor connected with the sensing amplifying module can output the divided voltage signal to the sensing amplifying module.
In this embodiment, the voltage dividing module is provided to divide the dc voltage provided by the voltage stabilizing module, so as to obtain a voltage signal after the voltage division, and lay a cushion for improving the detection precision of the subsequent sensing amplifying module.
In one embodiment, the sense amplifier module includes a first operational amplifier assembly, a sensor assembly, and a second operational amplifier assembly;
the positive input end of the first operational amplification component is connected with the first resistor, the negative input end of the first operational amplification component is connected with the output end of the first operational amplification component, and the output end of the first operational amplification component is connected with the positive input end of the second operational amplification component and the positive electrode of the sensor component; the inverting input end of the second operational amplification assembly is connected with the negative electrode of the sensor assembly, and the output end of the second operational amplification assembly is connected with the digital-to-analog conversion module.
The first operational amplifier component refers to an operational amplifier component with the same-direction input and the amplification factor of 1, and has high input impedance and low output impedance.
Specifically, the non-inverting input end of the first operational amplification component is connected with the first resistor, the inverting input end of the first operational amplification component is connected with the output end of the first operational amplification component, and the amplification factor of the first operational amplification component is 1, so that the first operational amplification component can be regarded as a voltage follower, the output is a voltage signal after voltage division output by the voltage division module, and the voltage signal output by the voltage follower is approximately an input voltage signal, and is in a high-resistance state for the front-stage component and in a low-resistance state for the rear-stage component, and therefore, the first operational amplification component is arranged to play a role in buffering and isolation; further, the voltage signal output by the first operational amplification assembly after voltage division is regarded as direct current reference voltage, and the output end of the first operational amplification assembly is connected with the positive input end of the second operational amplification assembly and the positive electrode of the sensor assembly, so that the output end of the first operational amplification assembly can output the direct current reference voltage to the sensor assembly, the zero point of the sensor assembly is lifted upwards to the direct current reference voltage, the situation that the detection accuracy is reduced due to the fact that the negative electrode (0V) clipping occurs to the output signal of the sensor assembly is avoided, and the situation that the sensor assembly is damaged due to the fact that the signal is opposite in practical application is effectively avoided; furthermore, the inverting input end of the second operational amplification assembly is connected with the negative electrode of the sensor assembly, and the output end of the second operational amplification assembly is connected with the digital-to-analog conversion module, so that the output end of the second operational amplification assembly can send the amplified gas concentration detection signal output by the sensing amplification module to the digital-to-analog conversion module.
In this embodiment, the sensing amplification module can amplify the concentration of the detected gas, and output the amplified concentration to the digital-to-analog conversion module through the second operational amplification module of the sensing amplification module, in addition, the sensing amplification module further includes a first operational amplification module and a sensor module, the first operational amplification module can buffer and isolate the front and rear stage modules, and the first operational amplification module sends the output direct current reference voltage to the sensor module, so that the detection precision can be improved by enabling the zero point of the sensor module to rise.
In one embodiment, the sensor assembly includes a gas sensor and a third resistor;
one end of the third resistor is connected with the positive electrode of the gas sensor, and the other end of the third resistor is connected with the negative electrode of the gas sensor;
the gas sensor detects the gas concentration and outputs a gas concentration signal to the second operational amplifier assembly.
Specifically, the sensor assembly includes a gas sensor and a third resistor, the structure of which is shown in fig. 3, the gas sensor is composed of a waterproof and breathable film 410, an upper shell 420, a membrane electrode detecting element 430, a lower shell 440 and a PCB (Printed Circuit Board ) board 450, in order to overcome the situations of short service life and unstable sensor output signal caused by traditional liquid electrolyte leakage or dry, larger attenuation amplitude of sensor conduction efficiency, the membrane electrode detecting element is composed of a solid electrolyte membrane and an electrode material, the electrochemical formaldehyde sensor is taken as the gas sensor, the solid electrolyte membrane can be made of materials such as poly perfluorosulfonic acid, polyvinylidene fluoride or polymethyl methacrylate, the film thickness is 0.1-0.18 mm, the electrode material is commercial carbon-loaded platinum catalyst, the platinum content is 5-40%, and the electrode thickness is 0.03-0.08 mm; the gas sensor is provided with a positive electrode and a negative electrode, the positive electrode is connected with one end of the third resistor, and the negative electrode is connected with the other end of the third resistor, namely, the two ends of the gas sensor are connected with a high-precision third resistor of 1% in parallel, so that the energy storage in the gas sensor is consumed, and the recovery of the sensor to an initial state is accelerated; further, the gas sensor can detect the concentration of the gas to be detected, when the gas sensor reacts with the gas to be detected, which passes through the waterproof breathable film, the membrane electrode detection element can generate electrons capable of moving directionally, so that the resistance at two ends of the gas sensor can be reduced, the current flowing through the gas sensor is increased, but the reaction current is weak, and therefore, a gas concentration signal can be output to the second operational amplifier assembly.
Further, the resistance value of the third resistor ranges from 100 to 1000 omega; in order to reduce the interference of the external environment to the input/output signals and improve the detection accuracy, the PCB of the gas sensor can be arranged in a compact layout and wiring manner.
In this embodiment, the sensor assembly includes gas sensor and third resistance, and the setting of the membrane electrode detecting element in the gas sensor can improve gas sensor's detection stability and detection precision, and has parallelly connected the third resistance at gas sensor's both ends, can consume the inside energy storage of gas sensor for the sensor resumes initial state.
In one embodiment, the second operational amplifier component includes an operational amplifier, a negative feedback component, and a second capacitor.
The positive input end of the operational amplifier is connected with the positive electrode of the sensor assembly, the negative input end of the operational amplifier is connected with the negative electrode of the sensor assembly, and the output end of the operational amplifier is connected with the digital-to-analog conversion module; one end of the negative feedback component is connected with the inverting input end of the operational amplifier, and the other end of the negative feedback component is connected with the output end of the operational amplifier; the second capacitor is connected in parallel with the negative feedback component.
Specifically, the second operational amplification assembly comprises an operational amplifier, a negative feedback assembly and a second capacitor, wherein the positive input end of the operational amplifier is connected with the positive electrode of the sensor assembly, the negative input end of the operational amplifier is connected with the negative electrode of the sensor assembly, the operational amplifier receives a weak current signal output by the sensor assembly, the weak current signal is a gas concentration signal before being not amplified, the operational amplifier and the negative feedback assembly are utilized to amplify the weak current signal by a limiting multiple and convert the signal into a voltage signal, one end of the negative feedback assembly is connected with the negative input end of the operational amplifier, and the other end of the negative feedback assembly is connected with the output end of the operational amplifier; in addition, a second capacitor in the second operational amplification assembly is connected with the negative feedback assembly in parallel, the output end of the operational amplifier is connected with the digital-to-analog conversion module, the second capacitor and the negative feedback assembly form a low-pass filter for filtering high-frequency noise, and meanwhile, the second operational amplification assembly is prevented from self-oscillation, and the amplified gas concentration detection signal can be ensured to be stably input into the digital-to-analog conversion module.
Further, the second capacitance may be a 5% high precision chip type multilayer ceramic capacitor.
In this embodiment, the second operational amplifier assembly may be composed of an operational amplifier, a negative feedback assembly and a second capacitor, where the operational amplifier and the negative feedback assembly combine to achieve a basic signal amplifying function, and the low-pass filter formed by the negative feedback assembly and the second capacitor may also filter out high-frequency noise, so as to prevent self-oscillation of the second operational amplifier assembly and improve the detection accuracy of the gas concentration detection device.
In one embodiment, the negative feedback component comprises a fourth negative feedback resistor and a fifth negative feedback resistor;
one end of the fourth negative feedback resistor is connected with the inverting input end of the operational amplifier, and the other end of the fourth negative feedback resistor is connected with one end of the fifth negative feedback resistor; the other end of the fifth negative feedback resistor is connected with the output end of the operational amplifier.
Specifically, the negative feedback component is composed of a fourth negative feedback resistor and a fifth negative feedback resistor which are 1% high-precision resistors, the fourth negative feedback resistor and the fifth negative feedback resistor are connected in series and are connected with the operational amplifier in parallel, namely one end of the fourth negative feedback resistor is connected with the inverting input end of the operational amplifier, and the other end of the fifth negative feedback resistor is connected with the output end of the operational amplifier.
In this embodiment, the negative feedback component is formed by the fourth negative feedback resistor and the fifth negative feedback resistor, so that the input signal of the second operational amplifier component can be amplified by combining with the operational amplifier, and the detection accuracy is improved.
In one embodiment, the system further comprises an RC filter module;
the RC filter module comprises a sixth resistor and a third capacitor; one end of the sixth resistor is connected with the sensing amplification module, and the other end of the sixth resistor is connected with the digital-to-analog conversion module and one end of the third capacitor; the other end of the third capacitor is grounded.
The RC filter module filters an input signal by using a resistor and a capacitor, so that an output signal is stable.
Specifically, the RC filter module comprises a sixth resistor and a third capacitor, one end of the sixth resistor is connected with the sense amplifying module, the other end of the sixth resistor is connected with one end of the third capacitor, the other end of the third capacitor is grounded, and the amplified gas concentration detection signal input into the RC filter module by the sense amplifying module is filtered again by the sixth resistor and the third capacitor; the other end of the sixth resistor connected with the third capacitor is also connected with the digital-to-analog conversion module, so that the amplified gas concentration detection signal after filtering can be output to the digital-to-analog conversion module.
In this embodiment, the device is further provided with an RC filtering module, so that the input amplified gas concentration detection signal can be filtered again, and the detection accuracy is improved.
In one embodiment, as shown in fig. 4, the digital-to-analog conversion module includes an MCU chip U2, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, and a seventh resistor R7;
the MCU chip U2 is respectively connected with the temperature sensing module, one end of the fifth capacitor C5 and two ends of the fourth capacitor C4; one end of the fourth capacitor C4 is connected with the voltage stabilizing module, and the other end of the fourth capacitor C4 is grounded; the other end of the fifth capacitor C5 is connected with one end of the sixth capacitor C6 and grounded; the other end of the sixth capacitor C6 is connected with one end of a seventh resistor R7; the other end of the seventh resistor R7 is connected with the voltage stabilizing module.
The MCU is a micro control unit, also called a singlechip, which properly reduces the frequency and specification of the central processing unit, integrates the memory, the counter, the digital-to-analog conversion and the like on a single chip to form a chip-level computer, and performs different combination control for different application occasions.
Specifically, the filtered amplified gas concentration detection signal is output to the pin 14 of the MCU chip U2 in the digital-to-analog conversion module, where the pins to be used in the MCU chip U2 are: a common ground voltage pin 7, an internal voltage regulator pin 8, a working voltage pin 9, a first digital to analog conversion input pin 14, and a second digital to analog conversion input pin 20; in addition, the pin 20 of the MCU chip U2 is connected with the temperature sensing module, the pin 8 of the MCU chip U2 is connected with one end of the fifth capacitor C5, the pin 7 and the pin 9 of the MCU chip U2 are respectively connected with two ends of the fourth capacitor C4, one end of the fourth capacitor C4 is connected with the voltage stabilizing module, the other end of the fourth capacitor C4 is grounded, the fourth capacitor C4 is used as a decoupling capacitor, the anti-interference performance can be improved, and therefore a voltage signal output by the voltage stabilizing module can provide a stable voltage signal for the MCU chip U2; the other end of the fifth capacitor C5 is connected with one end of the sixth capacitor C6 and grounded, the other end of the sixth capacitor C6 is connected with one end of the seventh resistor R7, and the other end of the seventh resistor R7 is connected with the voltage stabilizing module, so that the stability of MCU output can be ensured.
In this embodiment, the digital-to-analog conversion function of the MCU chip may be used to perform digital-to-analog conversion processing on the signal input to the MCU, so as to support detection of the gas concentration.
In one embodiment, the temperature sensing module includes an NTC resistor and an eighth resistor;
one end of the NTC resistor is connected with the digital-to-analog conversion module and one end of the eighth resistor, and the other end of the NTC resistor is connected with the voltage stabilizing module; the other end of the eighth resistor is grounded.
Wherein NTC refers to thermistor phenomenon and material with negative temperature coefficient, which decrease exponentially with temperature rise resistance; the NTC resistor is a resistor made of NTC material, and has a resistance value of 10KΩ under normal environment (25 ℃); the eighth resistor is a high-precision resistor of 1%, and the resistance value of the high-precision resistor is not changed by the change of the ambient temperature.
Specifically, the temperature sensing module includes an NTC resistor and an eighth resistor, since the NTC resistor is greatly affected by temperature, the resistance of the NTC resistor is continuously reduced along with the increase of temperature, the NTC resistor is also increased along with the decrease of temperature, and the high-precision resistance is not changed by the change of ambient temperature, so that when the temperature sensing module detects the ambient temperature, a temperature detection signal is output to the digital-to-analog conversion module, and the temperature detection signal is the voltage difference between the NTC resistor and the eighth resistor.
In this embodiment, the temperature sensing module is provided, so that the ambient temperature can be efficiently detected, and accurate detection of the gas concentration under different ambient temperatures is supported.
In one embodiment, after the digital-to-analog conversion module converts the amplified gas concentration detection signal and the temperature detection signal into analog signals and outputs the analog signals, a computer is used to calculate the two analog signals, firstly, a relation curve between a voltage difference value between the NTC resistor and the eighth resistor and the ambient temperature is obtained to obtain the current ambient temperature, and the output of the gas concentration detection device is acquired for multiple times to fit a functional relation between the ambient temperature and the gas concentration detection signal, and the amplified gas concentration detection signal output by the gas concentration detection device is corrected by using the functional relation.
In one embodiment, the specific connection relationship of the circuit of the gas concentration detection device may be as shown in fig. 5, where the linear voltage stabilizer U1 and the first capacitor C1 form a voltage stabilizing module; the voltage division module comprises a first resistor R1 and a second resistor R2; the sensing amplification module comprises a first operational amplification component U3-B, a sensor component composed of a gas sensor U4 and a third resistor R3, and a second operational amplification component, wherein the second operational amplification component comprises an operational amplifier U3-A, a negative feedback component composed of a fourth negative feedback resistor R4 and a fifth negative feedback resistor R5, and a second capacitor C2; the RC filter module comprises a sixth resistor R6 and a third capacitor C3; the digital-to-analog conversion module comprises an MCU chip U2, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6 and a seventh resistor R7; the temperature sensing module includes an eighth resistor R8 and an NTC resistor R9.
In this embodiment, the first capacitor C1 is 10uF, the first resistor R1 is 1mΩ, the second resistor R2 is 100kΩ, the third resistor R3 is 100rΩ, the fourth negative feedback resistor R4 is 120kΩ, the fifth negative feedback resistor R5 is 1kΩ, the second capacitor C2 is 220nF, the sixth resistor R6 is 1kΩ, the third capacitor C3 is 10nF, the fourth capacitor C4 is 0.1uF, the fifth capacitor C5 is 1uF, the sixth capacitor C6 is 0.1uF, the seventh resistor R7 is 100kΩ, the eighth resistor R8 is 10kΩ, and the NTC resistor R9 is 10kΩ.
Specifically, taking an external voltage signal of +5v as an example, firstly inputting the external voltage signal of +5v into a pin 1 and a pin 3 of a linear voltage stabilizer U1, and outputting a stable voltage signal of +3v from a pin 5 of the linear voltage stabilizer; the first resistor R1 and the second resistor R2 divide +3V to obtain a reference voltage signal Vref of 0.272727V, and the voltage dividing module outputs the reference voltage signal to the first operational amplifier component U3-B; the first operational amplifier module U3-B performs voltage follow-up to still obtain 0.272727V voltage, and outputs the voltage to the gas sensor U4; when the sensor detects the gas in the surrounding environment, a weak gas concentration signal is output to the second operational amplification component, a stable voltage signal +3V is input to the upper port of the operational amplifier U3-A in the second operational amplification component, the operational amplifier U3-A in the second operational amplification component and the negative feedback component consisting of the fourth negative feedback resistor R4 and the fifth negative feedback resistor R5 amplify the weak gas concentration detection signal to obtain an amplified gas concentration detection signal, and in addition, the negative feedback component consisting of the fourth negative feedback resistor R4 and the fifth negative feedback resistor R5 and the second capacitor C2 can also form a low-pass filter for filtering; the amplified gas concentration detection signal is filtered again by an RC filter circuit consisting of a sixth resistor R6 and a third capacitor C3; the filtered amplified gas concentration detection signal is output to the pin 14 of the MCU chip U2, and the stable voltage signal +3v is input to the pin 9 of the MCU chip U2, the fourth capacitor C4, and the seventh resistor R7; the temperature detection signal output by the voltage division point in the middle of the eighth resistor R8 connected in series with the NTC resistor R9 of the temperature sensing module is output to the pin 20 of the MCU chip U2; the MCU chip receives the filtered amplified gas concentration detection signal and the temperature detection signal, converts the signals into analog signals and outputs the analog signals.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the utility model and are described in detail herein without thereby limiting the scope of the utility model. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the utility model, which are all within the scope of the utility model. Accordingly, the scope of the utility model should be assessed as that of the appended claims.
Claims (10)
1. The gas concentration detection device is characterized by comprising a voltage stabilizing module, a sensing amplification module, a digital-to-analog conversion module and a temperature sensing module;
the voltage stabilizing module outputs a voltage signal to the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module; the sensing amplification module detects the gas concentration and outputs an amplified gas concentration detection signal to the digital-to-analog conversion module; the temperature sensing module detects the ambient temperature and outputs a temperature detection signal to the digital-to-analog conversion module; the digital-to-analog conversion module converts the amplified gas concentration detection signal and the temperature detection signal into analog signals and outputs the analog signals.
2. The apparatus of claim 1, wherein the voltage regulator module comprises a linear voltage regulator and a first capacitor;
the input end of the linear voltage stabilizer is connected with an external voltage signal, the output end of the linear voltage stabilizer is respectively connected with one end of the first capacitor, the sensing amplifying module, the digital-to-analog conversion module and the temperature sensing module, and the other end of the first capacitor is grounded.
3. The apparatus of claim 1, further comprising a voltage dividing module;
the voltage division module comprises a first resistor and a second resistor; one end of the first resistor is connected with the voltage stabilizing module, the other end of the first resistor is connected with the sensing amplifying module and one end of the second resistor, and the other end of the second resistor is grounded.
4. The apparatus of claim 3, wherein the sense amp module comprises a first operational amp component, a sensor component, and a second operational amp component;
the positive input end of the first operational amplification component is connected with the first resistor, the negative input end of the first operational amplification component is connected with the output end of the first operational amplification component, and the output end of the first operational amplification component is connected with the positive input end of the second operational amplification component and the positive electrode of the sensor component; the inverting input end of the second operational amplification assembly is connected with the negative electrode of the sensor assembly, and the output end of the second operational amplification assembly is connected with the digital-to-analog conversion module.
5. The apparatus of claim 4, wherein the sensor assembly comprises a gas sensor and a third resistor;
one end of the third resistor is connected with the positive electrode of the gas sensor, and the other end of the third resistor is connected with the negative electrode of the gas sensor;
the gas sensor detects the gas concentration and outputs a gas concentration signal to the second operational amplification component.
6. The apparatus of claim 4, wherein the second operational amplification component comprises an operational amplifier, a negative feedback component, and a second capacitor;
the operational amplifier is connected with the voltage stabilizing module, the positive input end of the operational amplifier is connected with the positive electrode of the sensor assembly, the negative input end of the operational amplifier is connected with the negative electrode of the sensor assembly, and the output end of the operational amplifier is connected with the digital-to-analog conversion module; one end of the negative feedback component is connected with the inverting input end of the operational amplifier, and the other end of the negative feedback component is connected with the output end of the operational amplifier; the second capacitor is connected in parallel with the negative feedback component.
7. The apparatus of claim 6, wherein the negative feedback component comprises a fourth negative feedback resistor and a fifth negative feedback resistor;
one end of the fourth negative feedback resistor is connected with the inverting input end of the operational amplifier, and the other end of the fourth negative feedback resistor is connected with one end of the fifth negative feedback resistor; and the other end of the fifth negative feedback resistor is connected with the output end of the operational amplifier.
8. The apparatus of claim 1, further comprising an RC filter module;
the RC filter module comprises a sixth resistor and a third capacitor; one end of the sixth resistor is connected with the sensing amplification module, and the other end of the sixth resistor is connected with the digital-to-analog conversion module and one end of the third capacitor; the other end of the third capacitor is grounded.
9. The apparatus of claim 1, wherein the digital-to-analog conversion module comprises an MCU chip, a fourth capacitor, a fifth capacitor, a sixth capacitor, and a seventh resistor;
the MCU chip is respectively connected with the temperature sensing module, one end of the fifth capacitor and two ends of the fourth capacitor; one end of the fourth capacitor is connected with the voltage stabilizing module, and the other end of the fourth capacitor is grounded; the other end of the fifth capacitor is connected with one end of the sixth capacitor and grounded; the other end of the sixth capacitor is connected with one end of the seventh resistor; the other end of the seventh resistor is connected with the voltage stabilizing module.
10. The apparatus of claim 1, wherein the temperature sensing module comprises an NTC resistor and an eighth resistor;
one end of the NTC resistor is connected with the digital-to-analog conversion module and one end of the eighth resistor, and the other end of the NTC resistor is connected with the voltage stabilizing module; the other end of the eighth resistor is grounded.
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| CN202320270949.8U CN219533071U (en) | 2023-02-10 | 2023-02-10 | Gas concentration detection device |
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