阅读说明：本技术 火焰离子电流检测电路及方法、燃气设备 (Flame ion current detection circuit and method and gas equipment ) 是由 麻文山 吴恩豪 于 2020-04-15 设计创作，主要内容包括：本发明属于燃气设备技术领域,具体涉及一种火焰离子电流检测电路及方法、燃气设备。本发明旨在解决现有技术中仅能检测火焰的有无,无法对火焰离子电流的大小进行准确的检测的问题。本发明的火焰离子电流检测电路包括：正弦波信号源、火焰信号采集单元和火焰信号检测单元；所述正弦波信号源,用于产生正弦波电信号,并输出给所述火焰信号检测单元；所述火焰信号采集单元,用于采集火焰电信号,并输出给所述火焰信号检测单元；所述火焰信号检测单元,用于接收所述正弦波电信号和所述火焰电信号的叠加信号；根据检测的所述叠加信号的电压幅值和所述正弦波电信号的电压幅值,确定所述火焰电信号的电流。本发明可以实现对火焰离子电流的准确检测。(The invention belongs to the technical field of gas equipment, and particularly relates to a flame ion current detection circuit and method and gas equipment. The invention aims to solve the problem that in the prior art, the flame ionization current can not be accurately detected only by detecting whether flame exists or not. The flame ion current detection circuit of the present invention includes: the device comprises a sine wave signal source, a flame signal acquisition unit and a flame signal detection unit; the sine wave signal source is used for generating a sine wave electric signal and outputting the sine wave electric signal to the flame signal detection unit; the flame signal acquisition unit is used for acquiring flame electric signals and outputting the flame electric signals to the flame signal detection unit; the flame signal detection unit is used for receiving a superposition signal of the sine wave electric signal and the flame electric signal; and determining the current of the flame electric signal according to the detected voltage amplitude of the superposed signal and the detected voltage amplitude of the sine wave electric signal. The invention can realize accurate detection of flame ion current.)

1. A flame ion current detection circuit, comprising: the device comprises a sine wave signal source, a flame signal acquisition unit and a flame signal detection unit;

the sine wave signal source is used for generating a sine wave electric signal and outputting the sine wave electric signal to the flame signal detection unit;

the flame signal acquisition unit is used for acquiring flame electric signals and outputting the flame electric signals to the flame signal detection unit;

the flame signal detection unit is used for receiving a superposition signal of the sine wave electric signal and the flame electric signal; and determining the current of the flame electric signal according to the detected voltage amplitude of the superposed signal and the detected voltage amplitude of the sine wave electric signal.

2. The circuit of claim 1, wherein the sine wave signal source comprises: the low-voltage direct-current power supply comprises a low-voltage direct-current power supply, an oscillating circuit and a coupling circuit;

the oscillating circuit is used for generating a sine wave signal based on a direct-current voltage signal provided by the low-voltage direct-current power supply and outputting the sine wave signal to the coupling circuit;

the coupling circuit is used for coupling the sine wave signal to the flame signal acquisition unit.

3. The circuit of claim 2, wherein the oscillating circuit comprises:

the circuit comprises a first resistor, a second resistor, a first capacitor, a second capacitor, a third capacitor, a diode, a first transistor and a transformer;

the first end of the first transistor is connected with the direct-current voltage signal through the first capacitor, the second end of the first transistor is connected with a power supply through the first resistor, and the third end of the first transistor is grounded through the second resistor;

the primary coil of the transformer is connected in parallel with the first capacitor;

one end of a secondary coil of the transformer is connected with the second end of the first transistor, and the other end of the secondary coil of the transformer is grounded through the third capacitor and is used for outputting an alternating current signal;

one end of the second capacitor is connected with the second end of the first transistor, and the other end of the second capacitor is grounded; the diode is connected in parallel with the second capacitor.

4. The circuit of claim 3, wherein the oscillating circuit further comprises: a third resistor and a switching device;

one end of the third resistor is connected with the second end of the first transistor, and the other end of the third resistor is connected with the first end of the switching device; a second terminal of the switching device is grounded;

the switching device is configured to receive a switching control signal and turn on or off the first end and the second end of the switching device under the control of the switching control signal.

5. The circuit of any one of claims 1-4, wherein the flame signal detection unit comprises: the circuit comprises a sampling circuit, a switching circuit and a voltage modulation circuit;

the sampling circuit is used for sampling the superposed signal to obtain a voltage sampling value of the superposed signal and outputting the voltage sampling value to the switch circuit;

the switch circuit is used for receiving the voltage sampling value and outputting the voltage sampling value to the voltage modulation circuit when the voltage sampling value is larger than the conduction threshold value of the switch circuit;

the voltage modulation circuit is used for carrying out voltage modulation on the voltage sampling value to obtain detection voltage so as to determine the current value of the flame electric signal according to the detection voltage.

6. The circuit of claim 5, wherein the sampling circuit comprises: a fourth resistor, a fifth resistor and a fourth capacitor;

one end of the fourth resistor is connected with the sine wave signal source, and the other end of the fourth resistor is connected with the switching circuit and one end of the fifth resistor; the other end of the fifth resistor is grounded; the fourth capacitor is connected in parallel with the fifth resistor.

7. The circuit of claim 5, wherein the switching circuit comprises: a second transistor;

and the first end of the second transistor is connected with the sampling circuit, the second end of the second transistor is connected with the modulation circuit, and the third end of the second transistor is grounded.

8. The circuit of claim 5, wherein the voltage modulation circuit comprises: a sixth resistor and a seventh resistor;

one end of the sixth resistor is connected with a power supply, and the other end of the sixth resistor is connected with an output end and one end of the seventh resistor; the other end of the seventh resistor is connected with the second end of the switch circuit.

9. A gas-fired appliance characterized by comprising a flame ionization current detection circuit according to any one of claims 1 to 8.

10. A flame ion current detection method is characterized by comprising the following steps:

generating a sine wave electrical signal;

collecting flame electric signals, and superposing the flame electric signals to the sine wave electric signals to obtain superposed signals;

and detecting the voltage amplitude of the superimposed signal, and determining the current of the flame electric signal according to the voltage amplitude of the superimposed signal and the voltage amplitude of the sine wave electric signal.

Technical Field

The invention relates to the technical field of gas equipment, in particular to a flame ion current detection circuit and method and gas equipment.

Background

In the field of gas equipment such as gas water heaters, gas wall-mounted furnaces, gas hot-blast stoves, gas boilers and the like, the efficiency and the exhaust emission during gas combustion are related to the combustion condition, and the combustion condition is related to the mixing ratio of gas and air and directly reflects the change of flame. The mixing proportion of the gas and the air is adjusted by accurately monitoring the size of the flame ion current, so that the heat efficiency of the gas product and the exhaust emission standard are improved.

In the prior art, 220V ac power can be transformed into 110V ac power by a power frequency transformer, and the 110V ac power is applied between a flame needle and a casing to detect a flame electric signal.

However, the 220v ac provided by the power grid has a large variation, which directly affects the variation of the flame ion current, so that only the presence or absence of flame can be detected, and the flame ion current cannot be accurately detected.

Disclosure of Invention

The method aims to solve the problems in the prior art that only flame can be detected and the size of flame ion current cannot be accurately detected in the prior art.

In a first aspect, the present invention provides a flame ionization current detection circuit comprising: the device comprises a sine wave signal source, a flame signal acquisition unit and a flame signal detection unit;

the sine wave signal source is used for generating a sine wave electric signal and outputting the sine wave electric signal to the flame signal detection unit;

the flame signal acquisition unit is used for acquiring flame electric signals and outputting the flame electric signals to the flame signal detection unit;

the flame signal detection unit is used for receiving a superposition signal of the sine wave electric signal and the flame electric signal; and determining the current of the flame electric signal according to the detected voltage amplitude of the superposed signal and the detected voltage amplitude of the sine wave electric signal.

In one possible design, the sinusoidal signal source includes: the low-voltage direct-current power supply comprises a low-voltage direct-current power supply, an oscillating circuit and a coupling circuit;

the oscillating circuit is used for generating a sine wave signal based on a direct-current voltage signal provided by the low-voltage direct-current power supply and outputting the sine wave signal to the coupling circuit;

the coupling circuit is used for coupling the sine wave signal to the flame signal acquisition unit.

In one possible design, the oscillation circuit includes:

the circuit comprises a first resistor, a second resistor, a first capacitor, a second capacitor, a third capacitor, a diode, a first transistor and a transformer;

the first end of the first transistor is connected with the direct-current voltage signal through the first capacitor, the second end of the first transistor is connected with a power supply through the first resistor, and the third end of the first transistor is grounded through the second resistor;

the primary coil of the transformer is connected in parallel with the first capacitor;

one end of a secondary coil of the transformer is connected with the second end of the first transistor, and the other end of the secondary coil of the transformer is grounded through the third capacitor and is used for outputting an alternating current signal;

one end of the second capacitor is connected with the second end of the first transistor, and the other end of the second capacitor is grounded; the diode is connected in parallel with the second capacitor.

In one possible design, the oscillation circuit further includes: a third resistor and a switching device;

one end of the third resistor is connected with the second end of the first transistor, and the other end of the third resistor is connected with the first end of the switching device; a second terminal of the switching device is grounded;

the switching device is configured to receive a switching control signal and turn on or off the first end and the second end of the switching device under the control of the switching control signal.

In one possible design, the flame signal detection unit includes: the circuit comprises a sampling circuit, a switching circuit and a voltage modulation circuit;

the sampling circuit is used for sampling the superposed signal to obtain a voltage sampling value of the superposed signal and outputting the voltage sampling value to the switch circuit;

the switch circuit is used for receiving the voltage sampling value and outputting the voltage sampling value to the voltage modulation circuit when the voltage sampling value is larger than the conduction threshold value of the switch circuit;

the voltage modulation circuit is used for carrying out voltage modulation on the voltage sampling value to obtain detection voltage so as to determine the current value of the flame electric signal according to the detection voltage.

In one possible design, the sampling circuit includes: a fourth resistor, a fifth resistor and a fourth capacitor;

one end of the fourth resistor is connected with the sine wave signal source, and the other end of the fourth resistor is connected with the switching circuit and one end of the fifth resistor; the other end of the fifth resistor is grounded; the fourth capacitor is connected in parallel with the fifth resistor.

In one possible design, the switching circuit includes: a second transistor;

and the first end of the second transistor is connected with the sampling circuit, the second end of the second transistor is connected with the modulation circuit, and the third end of the second transistor is grounded.

In one possible design, the voltage modulation circuit includes: a sixth resistor and a seventh resistor;

one end of the sixth resistor is connected with a power supply, and the other end of the sixth resistor is connected with an output end and one end of the seventh resistor; the other end of the seventh resistor is connected with the second end of the switch circuit.

In one possible design, the signal detection unit further includes: a filter circuit;

one end of the filter circuit is connected with the modulation circuit, and the other end of the filter circuit is connected with the output end.

In one possible design, the signal detection unit further includes: a voltage stabilizing circuit;

the voltage stabilizing circuit is connected between the sampling circuit and the switch circuit and used for limiting the input voltage of the switch circuit.

In a second aspect, the present invention provides a gas-fired appliance comprising: the circuit as described above in the first aspect and in various possible designs of the first aspect.

In a third aspect, the present invention provides a flame ion current detection method, including:

generating a sine wave electrical signal;

collecting flame electric signals, and superposing the flame electric signals to the sine wave electric signals to obtain superposed signals;

and detecting the voltage amplitude of the superimposed signal, and determining the current of the flame electric signal according to the voltage amplitude of the superimposed signal and the voltage amplitude of the sine wave electric signal.

As can be understood by those skilled in the art, the invention provides a flame ion current detection circuit, a method and gas equipment, wherein the flame ion current detection circuit comprises: the device comprises a sine wave signal source, a flame signal acquisition unit and a flame signal detection unit; the sine wave signal source is used for generating a sine wave electric signal and outputting the sine wave electric signal to the flame signal detection unit; the flame signal acquisition unit is used for acquiring flame electric signals and outputting the flame electric signals to the flame signal detection unit; the flame signal detection unit is used for receiving a superposition signal of the sine wave electric signal and the flame electric signal; and determining the current of the flame electric signal according to the detected voltage amplitude of the superposed signal and the detected voltage amplitude of the sine wave electric signal. The sine wave electric signal generated by the sine wave signal source is superposed with the flame electric signal collected by the flame signal collecting unit, the variation value of the voltage amplitude of the obtained superposed signal relative to the voltage amplitude of the sine wave signal is in a linear relation with the current value of the flame electric signal, and the accurate flame ion current value can be obtained by detecting the variation of the amplitude of the superposed signal.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the following briefly introduces the drawings needed to be used in the description of the embodiments or the prior art, and obviously, the drawings in the following description are some embodiments of the present invention, and those skilled in the art can obtain other drawings according to the drawings without inventive labor.

Fig. 1 is a schematic structural diagram of a flame ion current detection circuit according to an embodiment of the present invention;

FIG. 2 is a schematic waveform diagram of an electrical sine wave signal generated by a sine wave signal source according to another embodiment of the present invention;

FIG. 3 is a schematic waveform diagram of a superimposed signal in the presence of a flame according to yet another embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a flame ionization current detection circuit according to another embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a flame ionization current detection circuit according to another embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a flame ionization current detection circuit according to another embodiment of the present invention;

fig. 7 is a schematic structural diagram of a flame ion current detection circuit according to another embodiment of the present invention.

Reference numerals:

10: a sine wave signal source; 20: a flame signal acquisition unit; 30: a flame signal detection unit; 11: a low voltage DC power supply; 12: an oscillation circuit; 13: a coupling circuit; 31: a sampling circuit; 32 a switching circuit; 33: a voltage modulation circuit; 34: a filter circuit; 35: a voltage stabilizing circuit; r1: a first resistor; r2: a second resistor; r3: a third resistor; r4: a fourth resistor; r5: a fifth resistor; r6: a sixth resistor; r7: a seventh resistor; r8: an eighth resistor; c1: a first capacitor; c2: a second capacitor; c3: a third capacitor; c4: a fourth capacitor; c5: a fifth capacitor; c6: a sixth capacitor; d1: a diode; d2: a voltage stabilizing tube; t1: a transformer; q1: a first transistor; q2: a second transistor; VCC: a direct current voltage signal; VDD: a power source; SW: a switching device.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the field of gas equipment such as gas water heaters, gas wall-mounted furnaces, gas hot-blast stoves, gas boilers and the like, the efficiency and the exhaust emission during gas combustion are related to the combustion condition, and the combustion condition is related to the mixing ratio of gas and air and directly reflects the change of flame. The mixing proportion of the gas and the air is adjusted by accurately monitoring the size of the flame ion current, so that the heat efficiency of the gas product and the exhaust emission standard are improved.

In prior art, can be through power frequency transformer with 220V alternating current vary voltage for 110V alternating current, apply this 110V alternating current between flame needle and casing, detect the flame signal of telecommunication, however, the 220V alternating current that the electric wire netting provided changes greatly, directly influences the change of flame ionic current size for only can detect the existence of flame, can't carry out accurate detection to flame ionic current's size. Based on this, the embodiment of the invention provides a flame ion current detection circuit, which can accurately detect the magnitude of flame ion current.

The flame ion current detection circuit provided by the embodiment generates a standard sine wave electric signal through a sine wave signal source, and superimposes the sine wave signal and the flame electric signal, wherein the offset of the obtained superimposed signal relative to the sine wave electric signal is in a linear relationship with the flame ion current. By detecting the offset, detection voltage linearly related to the flame ion current can be obtained, so that the flame ion current can be accurately detected.

The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

Fig. 1 is a schematic structural diagram of a flame ion current detection circuit according to an embodiment of the present invention. As shown in fig. 1, the circuit includes: the device comprises a sine wave signal source 10, a flame signal acquisition unit 20 and a flame signal detection unit 30.

The sine wave signal source 10 is configured to generate a sine wave electrical signal and output the sine wave electrical signal to the flame signal detection unit 30.

The flame signal collecting unit 20 is configured to collect a flame electrical signal and output the flame electrical signal to the flame signal detecting unit 30.

The flame signal detection unit 30 is configured to receive a superimposed signal of the sine wave electrical signal and the flame electrical signal; and determining the current of the flame electric signal according to the detected voltage amplitude of the superposed signal and the detected voltage amplitude of the sine wave electric signal.

In this embodiment, as shown in fig. 2, the sine wave electric signal generated by the sine wave signal source 10 is a high-voltage high-frequency sine wave electric signal, and optionally, the center value of the sine wave electric signal is 0V, the peak value of the sine wave electric signal may be 150V, and the frequency of the sine wave electric signal may be 25 kHz.

The flame signal collecting unit 20 refers to a device that can collect a flame signal, such as a flame pin.

The working process of the flame ion current detection circuit provided by the embodiment is as follows: and the sine wave signal source 10 generates a sine wave electric signal and outputs the sine wave electric signal to the flame signal detection unit 30. And the flame signal acquisition unit 20 is used for acquiring flame electric signals and outputting the flame electric signals to the flame signal detection unit 30. A flame signal detection unit 30 that receives a superimposed signal of the sine wave electric signal and the flame electric signal; and determining the current of the flame electric signal according to the detected voltage amplitude of the superposed signal and the detected voltage amplitude of the sine wave electric signal. Specifically, as shown in fig. 2, when there is no flame at the flame needle, the waveform of the superimposed signal obtained by the flame signal detection unit 30 is the same as the sine wave electric signal generated by the sine wave signal source 10. When flame exists at the flame needle, due to the one-way conductive characteristic of flame current, as shown in fig. 3, the signal at the flame needle is pulled down, the waveform of the superimposed signal is shifted downward, the offset can be determined according to the voltage amplitude of the sine wave signal and the voltage amplitude of the superimposed signal, the magnitude of the offset is in a linear relation with the magnitude of the flame current, and the current of the flame electric signal can be obtained by detecting the offset through the flame signal detection unit 30.

The flame signal detection unit 30 may determine the current of the flame electrical signal according to the voltage amplitude of the superimposed signal and the voltage amplitude of the sine wave electrical signal, for example, the offset of the superimposed signal may be obtained according to the voltage amplitude of the ground signal and the voltage amplitude of the sine wave electrical signal through the charge-discharge principle of the capacitor, and further the current of the flame electrical signal may be obtained, and the offset of the superimposed signal may also be obtained according to the voltage amplitude of the ground signal and the voltage amplitude of the sine wave electrical signal through the principles of resistive voltage division and capacitive shaping, so as to obtain the current of the flame electrical signal, which is not limited in this embodiment.

The flame ion current detection circuit provided by this embodiment superimposes the sine wave electrical signal generated by the sine wave signal source 10 and the flame electrical signal collected by the flame signal collection unit 20, so that the variation value of the voltage amplitude of the obtained superimposed signal relative to the voltage amplitude of the sine wave signal has a linear relationship with the current value of the flame electrical signal, and the variation of the amplitude of the superimposed signal is detected, thereby obtaining the accurate flame ion current value.

Fig. 4 is a schematic structural diagram of a flame ion current detection circuit according to another embodiment of the present invention, and on the basis of the foregoing embodiment, the present embodiment describes in detail a sinusoidal wave signal source 10, where the sinusoidal wave signal source 10 includes: a low-voltage direct-current power supply 11, an oscillation circuit 12 and a coupling circuit 13;

the oscillation circuit 12 is configured to generate a sine wave signal based on a dc voltage signal VCC provided by the low-voltage dc power supply 11, and output the sine wave signal to the coupling circuit 13;

the coupling circuit 13 is configured to couple the sine wave signal to the flame signal collecting unit 20.

In this embodiment, there are various ways for the low voltage dc power supply 11 to generate the dc voltage signal VCC. For example, ac power may be input, and a dc voltage signal VCC may be output after shaping, transforming, and stabilizing, or dc power may be input, and a corresponding dc voltage signal VCC may be output after voltage conversion.

Alternatively, the oscillating circuit 12 may be in various forms, and may be, for example, a transformer-fed oscillating circuit 12, an inductor-fed oscillating circuit 12, a capacitor-fed oscillating circuit 12, or an RC bridge oscillating circuit 12.

The sine wave signal source 10 according to the present embodiment can generate a high-frequency and high-voltage standard sine wave by using low-voltage dc power. The cost of the oscillating circuit 12 is low, the circuit structure is simple, and the stability is high.

Fig. 5 is a schematic structural diagram of a flame ion current detection circuit according to yet another embodiment of the present invention, and based on the above-mentioned embodiment, for example, based on the circuit shown in fig. 4, the oscillation circuit 12 of the sine wave signal source 10 is illustrated in this embodiment. As shown in fig. 5, the oscillation circuit 12 includes: the circuit comprises a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a diode D1, a first transistor Q1 and a transformer T1.

The first transistor Q1 has a first terminal connected to the dc voltage signal VCC through the first capacitor C1, a second terminal connected to the power supply VDD through the first resistor R1, and a third terminal connected to ground through the second resistor R2.

The primary coil of the transformer T1 is connected in parallel with the first capacitor C1.

One end of the secondary coil of the transformer T1 is connected to the second end of the first transistor Q1, and the other end is grounded through the third capacitor C3 and is used for outputting an ac signal.

One end of the second capacitor C2 is connected to the second end of the first transistor Q1, and the other end is grounded; the diode D1 is connected in parallel with the second capacitor C2.

Specifically, the oscillation of the circuit can be realized by the positive feedback formed by the transformer T1 and the first transistor Q1, and a sine wave signal can be generated.

The flame ion current detection circuit that this embodiment provided can produce the high-pressure sine wave signal of high frequency of more standard through adopting transformer feedback formula oscillation circuit 12, and the cost is lower, easily realizes to through setting up second resistance R2 in this circuit, can adjust the amplitude of the sine wave signal who produces, be convenient for carry out the circuit debugging, and satisfy the manifold demand of sine wave signal amplitude.

Optionally, as shown in fig. 5, the oscillation circuit 12 further includes: a third resistor R3 and a switching device SW;

one end of the third resistor R3 is connected to the second end of the first transistor Q1, and the other end is connected to the first end of the switching device SW; a second terminal of the switching device SW is grounded.

The switching device SW is configured to receive a switching control signal, and turn on or off the first terminal and the second terminal of the switching device SW under the control of the switching control signal.

In this embodiment, the switching device SW is provided, so that the oscillation circuit 12 can be turned off, and the situations that the oscillation circuit 12 is always in a working state, so that the energy consumption is too large and the circuit is damaged are avoided.

Fig. 6 is a schematic structural diagram of a flame ion current detection circuit according to another embodiment of the present invention, as shown in fig. 6, on the basis of the above-mentioned embodiment, for example, on the basis of the embodiment shown in fig. 1, the present embodiment describes a flame signal detection unit 30 in detail, where the flame signal detection unit 30 includes: a sampling circuit 31, a switching circuit 32, and a voltage modulation circuit 33.

The sampling circuit 31 is configured to sample the superimposed signal, obtain a voltage sampling value of the superimposed signal, and output the voltage sampling value to the switching circuit 32.

The switch circuit 32 is configured to receive the voltage sampling value, and output the voltage sampling value to the voltage modulation circuit 33 when the voltage sampling value is greater than a conduction threshold of the switch circuit 32;

the voltage modulation circuit 33 is configured to perform voltage modulation on the voltage sampling value to obtain a detection voltage, so as to determine a current value of the flame electrical signal according to the detection voltage.

In the specific implementation process, the sine wave signal source 10 generates a sine wave electrical signal and outputs the sine wave electrical signal to the flame signal detection unit 30, the flame signal collection unit 20 collects a flame electrical signal and outputs the flame electrical signal to the flame signal detection unit 30, the sampling circuit 31 of the flame signal detection unit 30 samples a superimposed signal of the sine wave electrical signal and the flame electrical signal to obtain a voltage sampling value of the superimposed signal, the sampled value is zero in the absence of flame, the sampled value is related to the offset of the superimposed signal with respect to the sinusoidal electrical signal in the presence of flame, the voltage sampled value is sent to the switching circuit 32, the switching circuit 32 is adapted, according to the voltage sampled value, to switch on in the presence of flame, switch off in the absence of flame, switch on, the sampling value is output to the voltage modulation circuit 33 for modulation to obtain a detection voltage within a target range, and optionally, the detection voltage may be output to the microcontroller MCU for related processing. The offset, namely the voltage sampling value, is in a linear relation with the flame current, so that the detection voltage is in a linear relation with the flame current, and the accurate detection of the flame ion current is realized.

In this embodiment, when there is a flame, the offset of the superimposed signal with respect to the sine wave signal is sampled by the sampling circuit 31 to obtain a sampling voltage value linearly related to the flame ion current, the switching tube is turned on according to the sampling voltage value, and the sampling voltage value is adjusted to a suitable range by the voltage modulation circuit 33 to obtain a detection voltage representing the size of the flame ion current.

Fig. 7 is a schematic structural diagram of a flame ion current detection circuit according to another embodiment of the present invention, and on the basis of the above embodiment, the present embodiment describes in detail a sampling circuit 31, and as shown in fig. 7, the sampling circuit 31 may include: a fourth resistor R4, a fifth resistor R5 and a fourth capacitor C4.

One end of the fourth resistor R4 is connected to the sine wave signal source, and the other end is connected to the switch circuit 32 and one end of the fifth resistor R5; the other end of the fifth resistor R5 is grounded; the fourth capacitor C4 is connected in parallel with the fifth resistor R5.

Alternatively, as shown in fig. 7, the switching circuit 32 may include: and a second transistor Q2.

The second transistor Q2 has a first terminal connected to the sampling circuit 31, a second terminal connected to the modulation circuit, and a third terminal connected to ground.

In this embodiment, the second transistor Q2 may be a field effect transistor or a bipolar transistor.

Alternatively, as shown in fig. 7, the voltage modulation circuit 33 includes: a sixth resistor R6 and a seventh resistor R7.

One end of the sixth resistor R6 is connected with a power supply VDD, and the other end of the sixth resistor R6 is connected with the output end and one end of the seventh resistor R7; the other end of the seventh resistor R7 is connected to the second end of the switch circuit 32.

Optionally, as shown in fig. 7, the signal detection unit further includes: a filter circuit 34.

One end of the filter circuit 34 is connected to the modulation circuit, and the other end is connected to the output terminal. The detection voltage output by the voltage modulation circuit 33 can be filtered and shaped by arranging the filter circuit 34, and based on the filtering and shaping, when the detection voltage after filtering and shaping is input into the MCU for analog-to-digital sampling, the MCU can be prevented from being damaged due to the existence of interference signals.

Optionally, the filter circuit 34 may include a fifth capacitor C5, a sixth capacitor C6, and an eighth resistor R8. One end of the eighth resistor R8 is grounded through the sixth capacitor C6 and connected to the output terminal of the voltage modulation circuit 33, and the other end is grounded through the fifth capacitor C5 and connected to the OUT terminal.

Optionally, as shown in fig. 7, the signal detection unit further includes: a voltage stabilizing circuit 35.

The voltage stabilizing circuit 35 is connected between the sampling circuit 31 and the switch circuit 32, and is configured to limit the input voltage of the switch circuit 32. By providing the voltage stabilizing circuit 35, the output voltage of the sampling circuit 31 can be limited, thereby ensuring that the transistor of the switching circuit 32 is not damaged. For example, when the second transistor Q2 is a field effect transistor, the output voltage of the sampling circuit 31 may be limited to 40V or less.

Optionally, the voltage regulator circuit 35 may include a voltage regulator D2.

In a specific implementation process, due to the unidirectional flow characteristic of the flame ion current, when there is no flame, the flame signal collection unit 20, i.e., the flame, is in an off state with respect to ground, the current signals sampled by the sampling circuits 31R4, R5, and C4 are divided by R4 and R5, the center value of the sine wave electrical signal is equal to 0V on the upper plate of C4, i.e., the source end of the switching circuit 32Q2 is 0V, and the voltage value is also 0V because the gate end of Q2 is grounded, so that the voltage between the source end and the gate end of Q2 does not reach the on limit value of Q2, and therefore Q2 is in an off state, i.e., the switching circuit 32 is off, and therefore the output end is pulled up to VDD through R6. That is, when there is no flame and the flame current is zero, the voltage value of the output terminal OUT is VDD. When there is a flame, the sine wave electrical signal generated by the sine wave signal source 10 is applied between the flame signal collection unit 20, i.e. the flame needle, and the ground to obtain a superimposed signal of the sine wave electrical signal and the flame electrical signal, wherein the waveform of the superimposed signal is the same as that of the sine wave electrical signal, but due to the presence of the flame ion current, the waveform center value of the superimposed signal is shifted downward relative to the waveform center value of the sine wave electrical signal, and the magnitude of the offset is in linear relation to the magnitude of the current flame ion current. The superimposed signal is sampled by the sampling circuits 31R4, R5 and C4 to obtain an offset amplitude, the offset amplitude is loaded to the source end of the Q2, when the voltage difference between the source end and the gate end is larger than a conduction threshold value, the Q2 is conducted, the offset amplitude is output to the voltage modulation circuit 33 formed by R6 and R7, the offset amplitude is modulated into a value between 0V and VDD by the voltage modulation circuit 33 and is output to the microcontroller MCU through an OUT end as a detection voltage for relevant processing, and the detection voltage and the offset amplitude are in a linear relation, so that the size of the detection voltage represents the size of the flame ion current.

Specifically, the detection voltage can be calculated by the following formula (1) and formula (2):

wherein V1 is the detection voltage, V2 is the output voltage of the sampling circuit 31, V is the center value voltage of the superimposed signal, R4 is the fourth resistor, R5 is the fifth resistor, R6 is the sixth resistor, and R7 is the seventh resistor.

The flame ion current detection circuit provided by this embodiment generates a standard sinusoidal signal by the sinusoidal signal source 10, and performs sampling and modulation of the central value offset on the superimposed signal of the standard sinusoidal signal and the flame electric signal, so as to obtain a detection voltage linearly related to the flame ion current.

The invention further provides gas equipment which comprises the flame ion current detection circuit in the embodiment.

The gas equipment provided by this embodiment, through adopting the flame ion current detection circuit described in the above embodiment, can superpose the sine wave electric signal generated by the sine wave signal source 10 and the flame electric signal collected by the flame signal collection unit 20, and the change value of the voltage amplitude of the obtained superposed signal relative to the voltage amplitude of the sine wave signal has a linear relationship with the current value of the flame electric signal, and further, by detecting the change of the amplitude of the superposed signal, the accurate flame ion current value can be obtained.

Another embodiment of the present invention further provides a method for detecting flame ion current, including:

101. generating a sine wave electrical signal;

102. collecting flame electric signals, and superposing the flame electric signals to the sine wave electric signals to obtain superposed signals;

103. and detecting the voltage amplitude of the superimposed signal, and determining the current of the flame electric signal according to the voltage amplitude of the superimposed signal and the voltage amplitude of the sine wave electric signal.

The implementation principle of this embodiment is similar to that of the above embodiment, and is not described herein again.

In the flame ion current detection method provided by this embodiment, the sine wave electrical signal generated by the sine wave signal source 10 and the flame electrical signal collected by the flame signal collection unit 20 are superimposed, so that a change value of the voltage amplitude of the obtained superimposed signal relative to the voltage amplitude of the sine wave signal has a linear relationship with the current value of the flame electrical signal, and further, by detecting the change of the amplitude of the superimposed signal, an accurate flame ion current value can be obtained.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.