A catalytic combustion sensor and a dynamic balance measurement method thereof

Abstract

The present invention discloses a catalytic combustion sensor and a dynamic balance measurement method thereof, and relates to the technical field of catalytic combustion sensors. The sensor of the present invention comprises an explosion-proof stainless steel housing, in which a catalytic combustion compensation element and a catalytic combustion detection element are installed, a Wheatstone bridge is arranged on a circuit board, and an amplifier is connected to an MCU after signal amplification at the output end of the Wheatstone bridge, and ADC conversion is performed by an ADCInput arranged in the MCU for data acquisition; a controllable switch is controlled by the MCU to be connected to a fixed input voltage end, and the MCU periodicity and delay control circuit power-on time. The present invention can work intermittently, does not require continuous power supply, effectively reduces the power consumption of the sensor, prolongs the service life of the sensor, and the measurement result of the burner is accurate.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic combustion sensors, and in particular relates to a catalytic combustion sensor and a dynamic balance measurement method of the catalytic combustion sensor. Background Art

[0002] The catalytic combustion sensor is one of the earliest gas sensors used. Its basic working principle is: the combustible gas undergoes flameless combustion on the surface of the detection element carrier and the action of the catalyst. The carrier temperature rises, and the internal resistance value also increases accordingly. The change in resistance value is proportional to the concentration of the combustible gas. The concentration of the combustible gas can be calculated by measuring the change in resistance value, or the change in current and voltage caused by the change in resistance value. The catalytic combustion sensor is mainly used for the detection of combustible gases. It has good output signal linearity, stable performance, low price, and is not affected by non-combustible gases. In order to maintain the high temperature required for combustion, the catalytic combustion sensor needs to consume a large amount of power, usually more than 200mW, which increases the power consumption of the whole machine. Especially for the use time of portable instruments, it causes great restrictions.

[0003] There are some low-power alternatives, such as non-dispersive infrared, semiconductor and MEMS principle combustible gas sensors. However, each of them has limitations. For example, non-dispersive infrared sensors only respond to combustible gas with specific infrared absorption wavelengths; semiconductor gas sensors are easily affected by ambient temperature and humidity; MEMS principle sensing elements have limited catalyst content, and their service life and anti-poisoning performance are low. Therefore, catalytic combustion sensors are still the most widely used combustible gas sensors. Therefore, in view of the above problems, it is of great significance to provide a catalytic combustion sensor and its dynamic balance measurement method. Summary of the invention

[0004] A catalytic combustion sensor and a dynamic balance measurement method thereof of the present invention can work intermittently and do not require continuous power supply, thereby effectively reducing the power consumption of the sensor, extending the service life of the sensor, and providing accurate burner measurement results.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] A catalytic combustion sensor of the present invention comprises an explosion-proof stainless steel housing, a catalytic combustion compensation element and a catalytic combustion detection element are installed in the explosion-proof stainless steel housing, a metal sintered sheet with pores evenly distributed on the outer top surface of the explosion-proof stainless steel housing is provided, and a plurality of signal pins are installed at the bottom of the explosion-proof stainless steel housing;

[0007] A circuit board is installed on the inner bottom surface of the explosion-proof stainless steel housing, a Wheatstone bridge is arranged on the circuit board, the catalytic combustion compensation element and the catalytic combustion detection element are installed on the right side of the Wheatstone bridge, a first fixed resistor with a fixed value and a second fixed resistor with a fixed value are installed on the left side of the Wheatstone bridge, an amplifier is connected to the output end of the Wheatstone bridge, after signal amplification, it is connected to the MCU and the ADCInput arranged in the MCU performs ADC conversion and then performs data acquisition; a controllable switch is controlled by the MCU to be connected to the fixed input voltage end, and the MCU periodically and delays the power-on time of the control circuit.

[0008] Furthermore, the fixed input voltage terminal adopts a constant voltage power supply with an input voltage of 2-5V.

[0009] Furthermore, the controllable switch is any one of a triode, a field effect transistor, and a relay.

[0010] A dynamic balance measurement method for a catalytic combustion sensor comprises the following steps:

[0011] S01, turn on the controllable switch and power on the catalytic combustion sensor through the fixed input voltage terminal;

[0012] S02, each time the power is turned on, wait for the preheating time t1 to delay;

[0013] S03, recording and outputting the voltage signal V1M at time t1 as the initial value;

[0014] S04, as the signal increases, the rising rate gradually slows down, until the output signal rate rise rate decreases to a threshold close to zero;

[0015] S05, recording the voltage signal V1P at the moment when the output signal rate rise rate decreases to a threshold value close to zero in the above step, the time difference Δt1 at this moment, and the time value (t1+Δt1) at this moment;

[0016] S06, MCU controls the control switch to turn off;

[0017] S07, MCU calculates the signal change rate ΔV / Δt, that is, the change rate within Δt1 is ΔV1 / Δt1, that is, (V1P-V1M) / Δt1;

[0018] S08, the MCU calculates the gas concentration Reading = F*(ΔV1 / Δt1) at the time t1+Δt1, where F is a sensor calibration coefficient and is related to the characteristics of the sensor itself;

[0019] S09, waiting for the next detection cycle T, returning to step S01 at time t2 to repeat the operation, and calculating the gas concentration Reading = F*(ΔV2 / Δt2) at another time t2+Δt2.

[0020] Furthermore, the value range of t1 is 0-1000ms.

[0021] Furthermore, the value range of the detection period T is 5000-8000 ms.

[0022] The present invention has the following beneficial effects:

[0023] The present invention calculates the concentration of the gas by detecting the rate of change of the sensor signal, adopts a new type of dynamic balance method to measure the concentration of the combustible gas, periodically powers the detection element, and outputs a signal through a Wheatstone bridge balance circuit. The output level is different from the output potential difference between the output potential and the zero point of the conventional detection bridge, and the concentration of the combustible gas to be measured is calculated. The catalytic combustion sensor collects the rate of change of the catalytic combustion element after power-on to determine the concentration of the combustible gas to be measured. What is detected is a dynamic change rather than a steady-state level signal. The combustion sensor of the present invention can work intermittently and does not require continuous power supply, which effectively reduces the power consumption of the sensor, prolongs the service life of the sensor, and obtains accurate measurement results.

[0024] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0026] Figure 1 It is a structural schematic diagram of a catalytic combustion sensor of the present invention;

[0027] Figure 2 A schematic diagram of the circuit structure of a catalytic combustion sensor of the present invention;

[0028] Figure 3 A step diagram of a dynamic balance measurement method of a catalytic combustion sensor of the present invention;

[0029] Figure 4 A waveform diagram showing voltage and time data when the sensor of the present invention is working;

[0030] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0031] 1- catalytic combustion compensation element, 2- catalytic combustion detection element, 3- signal pin, 4- explosion-proof stainless steel housing, 5- metal sintered sheet, 6- Wheatstone bridge, 7- controllable switch, 8- second fixed value fixed resistor, 9- first fixed value fixed resistor, 10- fixed input voltage terminal, 11- amplifier, 12- MCU. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it is necessary to understand that the terms "inside", "outer top surface", "surface", "uniformly distributed", "bottom", "inner bottom surface", "right side", "left side", "upper surface" and the like indicate orientation or positional relationship, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred components or elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0034] Embodiment 1:

[0035] See also Figure 1-2 As shown, a catalytic combustion sensor of the present invention comprises an explosion-proof stainless steel housing 4, a catalytic combustion compensation element 1 and a catalytic combustion detection element 2 are installed in the explosion-proof stainless steel housing 4, a metal sintered sheet 5 with pores evenly distributed on the surface is arranged on the outer top surface of the explosion-proof stainless steel housing 4, and three signal pins 3 are installed at the bottom of the explosion-proof stainless steel housing 4, and the gas enters the sensor through the pores of the metal sintered sheet 5 on the top, reacts on the detection element, and is output at the signal pin 3;

[0036] A circuit board is installed on the bottom surface of the explosion-proof stainless steel shell 4, and a Wheatstone bridge 6 is arranged on the circuit board. The catalytic combustion compensation element 1 and the catalytic combustion detection element 2 are installed on the right side of the Wheatstone bridge 6, and the first fixed resistor 9 and the second fixed resistor 8 are installed on the left side of the Wheatstone bridge 6. The output end of the Wheatstone bridge 6 is connected to an amplifier 11, which is connected to the MCU12 after signal amplification and the ADCInput arranged in the MCU12 performs ADC conversion and then performs data acquisition; a controllable switch 7 controlled by the MCU12 is connected to the fixed input voltage terminal 10, and the MCU12 periodically and delays the power-on time of the control circuit.

[0037] The fixed input voltage terminal 10 uses a constant voltage power supply with an input voltage of 2V.

[0038] The controllable switch 7 is a triode.

[0039] like Figure 3-4 As shown, a dynamic balance measurement method of a catalytic combustion sensor includes the following steps:

[0040] S01, turn on the controllable switch 7, and power on the catalytic combustion sensor through the fixed input voltage terminal 10;

[0041] S02, each time the power is turned on, wait for the preheating time t1 to delay;

[0042] S03, recording and outputting the voltage signal V1M at time t1 as the initial value;

[0043] S04, as the signal increases, the rising rate gradually slows down, until the output signal rate rise rate decreases to a threshold close to zero;

[0044] S05, recording the voltage signal V1P at the moment when the output signal rate rise rate decreases to a threshold value close to zero in the above step, the time difference Δt1 at this moment, and the time value (t1+Δt1) at this moment;

[0045] S06, MCU12 controls the control switch 7 to be closed;

[0046] S07, MCU calculates the signal change rate ΔV / Δt, that is, the change rate within Δt1 is ΔV1 / Δt1, that is, (V1P-V1M) / Δt1;

[0047] S08, the MCU calculates the gas concentration Reading = F*(ΔV1 / Δt1) at the time t1+Δt1, where F is a sensor calibration coefficient and is related to the characteristics of the sensor itself;

[0048] S09, waiting for the next detection cycle T, returning to step S01 at time t2 to repeat the operation, and calculating the gas concentration Reading = F*(ΔV2 / Δt2) at another time t2+Δt2.

[0049] The value of t1 is 600ms.

[0050] The value of the detection period T is 6000ms.

[0051] Embodiment 2:

[0052] Its main structure is consistent with that of Example 1;

[0053] The fixed input voltage terminal 10 uses a fixed voltage power supply with an input voltage of 5V.

[0054] The controllable switch 7 is a relay.

[0055] like Figure 3-4 As shown, a dynamic balance measurement method for a catalytic combustion sensor, the steps of which are consistent with those of Example 1.

[0056] The value of t1 is 800ms.

[0057] The value of the detection period T is 8000 ms.

[0058] Advantages of the present invention: The present invention calculates the concentration of the gas by detecting the rate of change of the sensor signal, adopts a new type of dynamic balance method to measure the concentration of combustible gas, periodically powers the detection element, and outputs a signal through a Wheatstone bridge balance circuit. The output level is different from the output level of the conventional detection bridge. The concentration of the combustible gas to be measured is calculated based on the output potential difference between the output potential and the zero point. The catalytic combustion sensor collects the rate of change of the catalytic combustion element after power-on to determine the concentration of the combustible gas to be measured. What is detected is a dynamic change rather than a steady-state level signal. The combustion sensor of the present invention can work intermittently and does not require continuous power supply, which effectively reduces the power consumption of the sensor, extends the service life of the sensor, and obtains accurate measurement results.

[0059] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A dynamic balance measurement method for a catalytic combustion sensor, characterized in that: The steps include: S01, turning on the controllable switch (7), and powering on the catalytic combustion sensor through the fixed input voltage terminal (10); S02, each time the power is turned on, wait for the preheating time t1 to delay; S03, recording and outputting the voltage signal V1M at time t1 as the initial value; S04, as the signal increases, the rising rate gradually slows down, until the output signal rate rise rate decreases to a threshold close to zero; S05, recording the voltage signal V1P at the moment when the output signal rate rise rate decreases to a threshold value close to zero in the above steps, the time difference Δt1 at this moment, and the time value t1+Δt1 at this moment; S06, MCU (12) controls the controllable switch (7) to turn off; S07, MCU calculates the signal change rate ΔV / Δt, that is, the change rate within Δt1 is ΔV1 / Δt1, that is, (V1P-V1M) / Δt1; S08, the MCU calculates the gas concentration Reading = F*(ΔV1 / Δt1) at the time t1+Δt1, where F is a sensor calibration coefficient and is related to the characteristics of the sensor itself; S09, waiting for the next detection cycle T, returning to step S01 at time t2 to repeat the operation, and calculating the gas concentration Reading = F*(ΔV2 / Δt2) at another time t2+Δt2.

2. The dynamic balance measurement method of a catalytic combustion sensor according to claim 1, characterized in that: The value range of t1 is 0-1000ms.

3. The dynamic balance measurement method of a catalytic combustion sensor according to claim 1, characterized in that: The value range of the detection period T is 5000-8000 ms.

4. A catalytic combustion sensor for realizing the dynamic balance measurement method of a catalytic combustion sensor as claimed in any one of claims 1 to 3, comprising an explosion-proof stainless steel housing (4), characterized in that: A catalytic combustion compensation element (1) and a catalytic combustion detection element (2) are installed in the explosion-proof stainless steel housing (4); a metal sintered sheet (5) having pores evenly distributed on the surface is provided on the outer top surface of the explosion-proof stainless steel housing (4); and a plurality of signal pins (3) are installed on the bottom of the explosion-proof stainless steel housing (4); A circuit board is installed on the bottom surface of the explosion-proof stainless steel housing (4), a Wheatstone bridge (6) is arranged on the circuit board, the catalytic combustion compensation element (1) and the catalytic combustion detection element (2) are installed on the right side of the Wheatstone bridge (6), and a first fixed resistor (9) and a second fixed resistor (8) are installed on the left side of the Wheatstone bridge (6). The output end of the Wheatstone bridge (6) is connected to an amplifier (11) and connected to an MCU (12) after signal amplification, and ADC conversion is performed by an ADCInput arranged in the MCU (12) before data acquisition; a controllable switch (7) is controlled by the MCU (12) to be connected to a fixed input voltage end (10), and the MCU (12) periodically and delays the power-on time of the control circuit.

5. A catalytic combustion sensor according to claim 4, characterized in that: The fixed input voltage terminal (10) adopts a fixed voltage power supply with an input voltage of 2-5V.

6. A catalytic combustion sensor according to claim 4, characterized in that: The controllable switch (7) is any one of a triode, a field effect transistor and a relay.

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