Flame combustion detection circuit and servo motor opening confirmation method

Abstract

The invention provides a flame combustion detection circuit and a servo motor opening confirmation method, and relates to the technical field of gas appliance detection. A flame combustion detection circuit comprises a booster circuit, a square wave circuit, a current detection circuit and a flame detection circuit, the output end of the booster circuit is connected with the input end of the square wave circuit, and the output end of the square wave circuit is connected with the current detection circuit. And meanwhile, the current detection circuit is connected with the flame detection circuit through a single-pole double-throw relay K1. By means of the circuit, the accuracy of flame detection of the circuit is guaranteed, the function of detecting the magnitude of current flowing through the flame detection needle CN1 is added, the optimal gas-air mixing ratio is found accordingly, the working efficiency of the gas water heater is improved, and gas energy waste is avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of gas appliance detection, and specifically relates to a flame combustion detection circuit and a servo motor opening confirmation method. Background Art

[0002] The heat source of the heating gas water heater comes from the combustion of gas. Whether it burns and how good the combustion is are the key prerequisites for the operation of the entire control system.

[0003] Existing research on gas water heaters has primarily focused on determining whether the gas is ignited. This involves using a single-chip microcomputer to measure the voltage detection signal provided by the flame detection circuit and determine whether the gas is ignited based on the voltage value and waveform of the voltage detection signal. However, this method cannot determine the combustion status of the flame after ignition, resulting in a waste of gas resources and affecting the operating efficiency of the gas water heater. Summary of the Invention

[0004] In order to solve the above problems in the prior art, the present application provides a flame combustion detection circuit and a servo motor opening confirmation method.

[0005] In a first aspect, the present application provides a flame combustion detection circuit, the circuit comprising a boost circuit, a square wave circuit, a current detection circuit, and a flame detection circuit, wherein:

[0006] The output end of the boost circuit is connected to the input end of the square wave circuit, the output end of the square wave circuit is connected to the current detection circuit, and the current detection circuit is connected to the flame detection circuit through a single-pole double-throw relay K1;

[0007] The boost circuit is used to convert the input voltage into a high output voltage;

[0008] The square wave circuit is used to generate a square wave voltage composed of a positive voltage and a negative voltage to prevent the flame detection needle CN1 in the flame detection circuit from generating ionization;

[0009] The current detection circuit is used to provide a detection voltage to obtain a detection current flowing through the flame detection needle CN1 according to the detection voltage, and to obtain the optimal combustion condition of the flame according to the detection current;

[0010] The flame detection circuit is used to detect whether the flame is ignited.

[0011] In a possible implementation, the boost circuit includes an inductor L1, a transistor N1, a diode D1, and an electrolytic capacitor E1:

[0012] The input end of the inductor L1 is connected to the first voltage source, the output end is connected to the anode of the diode D1 through one end of the resistor R4, and the other end is connected to the resistor R6 and then to the collector of the transistor N1;

[0013] The cathode of the diode D1 is grounded through the electrolytic capacitor E1;

[0014] The emitter of the transistor N1 is grounded, and the base is grounded via a pull-down resistor R20 . Meanwhile, the base of the transistor N1 is connected to a single chip microcomputer via a resistor R14 , so that the single chip microcomputer controls the conduction of the transistor N1 .

[0015] In a possible implementation, the boost circuit further includes a protection subcircuit, which includes a voltage divider resistor R8, a voltage divider resistor R28, a voltage stabilizing diode ZD3, and a band-stop transistor N3, wherein:

[0016] The cathode of the diode D1 is connected to the voltage-dividing resistor R8, the first output end of the voltage-dividing resistor R8 is grounded through the voltage-dividing resistor R28, and the second output end of the voltage-dividing resistor R8 is connected to the cathode of the voltage-stabilizing diode ZD3;

[0017] One end of the positive electrode of the voltage stabilizing diode ZD3 is grounded via the capacitor C4, and the other end is connected to the base of the band-stop transistor N3;

[0018] The collector of the band-stop transistor N3 is connected to the base of the transistor N1 , and the emitter of the band-stop transistor N3 is grounded.

[0019] In a possible implementation, the square wave circuit includes a transistor P1, a capacitor C1, a transistor N4, a Zener diode ZD1, and a Zener diode ZD2, wherein:

[0020] The emitter of the transistor P1 is connected to the output end of the boost circuit, the output end of the boost circuit is connected to the base of the transistor P1 through a pull-up resistor R7, and the base of the transistor P1 is connected to the collector of the transistor N4 through a voltage divider resistor R21;

[0021] The emitter of the transistor N4 is grounded, one end of the base is grounded via a pull-down resistor R33, and the other end is connected to the single chip microcomputer via a resistor R31, so that the single chip microcomputer controls the conduction of the transistor N4;

[0022] The capacitor C1 is connected to the collector of the transistor P1 through the current limiting resistor R17, and the collector of the transistor P1 is grounded through the load resistor R26. At the same time, the first output end of the capacitor C1 is connected in series with the cathode of the Zener diode ZD1 and the anode of the Zener diode ZD2 and grounded.

[0023] In one possible implementation, the current detection circuit includes a voltage divider resistor R5, a current limiting resistor R1, a voltage divider resistor R3, a measuring resistor R24, and a second voltage source, wherein:

[0024] The voltage divider resistor R5 is connected in series with the current limiting resistor R18 and the single chip microcomputer via one end of the second intersection to determine whether the square wave circuit generates a square wave voltage, and is connected to the first parallel circuit consisting of the capacitor C2 and the resistor R23 via the other end of the second intersection;

[0025] The current limiting resistor R1 is connected to the first contact of the single-pole double-throw relay K1 through the third intersection, and is also connected to the voltage divider resistor R3 through the third intersection. The measuring resistor R24 ​​is connected in series with the flame detection needle CN2 and then in parallel with the capacitor C3 to form a second parallel circuit. The first parallel circuit is grounded through the second parallel circuit.

[0026] The voltage dividing resistor R3 is connected to the second parallel circuit via a fourth intersection, and is also connected in series with the current limiting resistor R19 and the single chip microcomputer via the fourth intersection to provide a detection voltage corresponding to the measuring resistor R24;

[0027] The square wave circuit is connected to the current limiting resistor R1 at one end through the first intersection and to the voltage divider resistor R5 at the other end. Meanwhile, the second voltage source is connected to the first parallel circuit through the resistor R11 and to the second parallel circuit through the resistor R12.

[0028] In a possible implementation, the flame detection circuit includes the flame detection needle CN1, a self-oscillation sub-circuit and a flame detection sub-circuit, wherein:

[0029] The input end of the flame detection needle CN1 is connected to the second contact of the single-pole double-throw relay K1, and is connected to the self-excited oscillation sub-circuit at one end and the flame detection sub-circuit at the fifth node through the resistor R30.

[0030] In one possible implementation, the flame detection subcircuit includes a voltage divider resistor R34, a third voltage source, a fourth voltage source, and a pull-up resistor R32, wherein:

[0031] The input end of the voltage divider resistor R34 is connected to the fifth node, the output end is connected to the anode of the diode D3 and the third voltage source in sequence through the sixth node, one end is connected to the cathode of the diode D4 and then to ground, and the other end is connected to the resistor R35, the resistor R36 and the single chip microcomputer in sequence;

[0032] The fourth voltage source is connected between the resistor R35 and the resistor R36 via the pull-up resistor R32 . The resistor R36 and the microcontroller are grounded via the capacitor C6 . Meanwhile, the voltage divider resistor R34 and the resistor R35 are grounded via the capacitor C5 .

[0033] In a possible implementation, the self-oscillation sub-circuit includes a transistor P2, a transistor N5, and a transformer T1, wherein:

[0034] Pin 6 of the secondary of the transformer T1 is grounded, one end of pin 5 is connected to the fifth intersection via a current-limiting resistor R37 and a capacitor C7, the other end of pin 5 is connected to the anode of a diode D5, the cathode of the diode D5 is connected to a discharge resistor R38 at one end through the seventh intersection and then to ground, and the other end is connected to pin 1 of the primary of the transformer T2 via a capacitor C8, the cathode of the diode D5 and the capacitor C8 are grounded via a voltage-stabilizing diode D6, and pin 2 of the primary of the transformer T2 is grounded, and a discharge pin CN8 is connected between pins 3 and 4 of the secondary;

[0035] Pin 3 of the main winding of the transformer T1 is connected to a fifth voltage source, and pin 2 is connected to the collector of the transistor N5. Pin 4 of the trigger winding of the transformer T1 is connected to a discharge resistor R40 at one end through an eighth intersection and then to the emitter of the transistor P2. The other end is connected to a discharge resistor R45 and then to the collector of the transistor P2. The base of the transistor P2 is connected to the microcontroller via a current-limiting resistor R42 to control the conduction of the transistor P2, and is connected to a sixth voltage source via a pull-up resistor R39. The emitter of the transistor P2 is also connected between the resistor R39 and the sixth voltage source.

[0036] Pin 1 of the trigger winding of the transformer T1 is connected to the input end of the discharge resistor R41. One end of the output end of the discharge resistor R41 is connected to the base of the transistor N5 and the other end is grounded through the capacitor C9. At the same time, the emitter of the transistor N5 is grounded.

[0037] In one possible implementation, the input end of the single-pole double-throw relay K1 is connected to the seventh voltage source, the output end is connected to the collector of the transistor N2, the voltage regulator diode D2 is connected in parallel with the single-pole double-throw relay K1, and the emitter of the transistor N2 is grounded. One end of the base is connected to the single-chip microcomputer through the resistor R22 to control the conduction of the transistor N2, and one end is grounded through the pull-down resistor R29.

[0038] In a second aspect, the present application provides a method for confirming the opening of a servo motor, applied to the circuit according to any one of claims 1 to 9, the method comprising:

[0039] When the gas water heater is installed for the first time, the gas output is adjusted by adjusting the opening of the servo motor of the gas water heater and the detection voltage corresponding to the measuring resistor R24 ​​detected by the single chip microcomputer is continuously obtained;

[0040] Calculating the detection current corresponding to the flame detection needle CN1 according to the detection voltage based on a preset calculation relationship, wherein the preset calculation relationship is determined according to the resistance values ​​of the measuring resistor R24, the voltage dividing resistor R3, and the current limiting resistor R1;

[0041] A target detection current with the largest value is obtained from a plurality of detection currents, a target opening of the servo motor corresponding to the target detection current is obtained, and the opening of the servo motor is adjusted according to the target opening.

[0042] This application provides a flame detection circuit and a servo motor opening confirmation method. This method adds a current detection scheme to the flame presence determination scheme. A low input voltage is converted into a high output square wave voltage through a boost circuit and a square wave circuit. This detection voltage is provided by a current detection circuit, and the detection current flowing through flame detection pin CN1 is calculated. The flame combustion status is determined based on the detection current. Simultaneously, the flame detection circuit determines whether discharge pin CN2 has been successfully ignited. This circuit ensures the accuracy of the circuit's flame detection and adds the ability to detect the magnitude of the current flowing through flame detection pin CN1. This allows the optimal gas-air mixture ratio to be determined, improving the operating efficiency of the gas water heater and avoiding gas energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0044] Figure 1 A schematic structural diagram of a flame combustion detection circuit provided in an embodiment of the present application;

[0045] Figure 2 A schematic structural diagram of a boost circuit provided in an embodiment of the present application;

[0046] Figure 3 A schematic diagram of the structure of a square wave circuit provided in an embodiment of the present application;

[0047] Figure 4 A schematic diagram of the structure of a current detection circuit provided in an embodiment of the present application;

[0048] Figure 5 A schematic structural diagram of a flame detection circuit provided in an embodiment of the present application;

[0049] Figure 6A circuit diagram of a single-pole double-throw relay provided in an embodiment of the present application;

[0050] Figure 7 A flow chart of a method for confirming the opening of a servo motor provided in an embodiment of the present application.

[0051] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0052] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0053] The terms "first," "second," "third," "fourth," and so forth (if any) in the description and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or sequential sequence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention described herein can, for example, be implemented in sequences other than those illustrated or described herein.

[0054] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0055] The heat source of a gas-fired water heater comes from the combustion of gas. Whether or not this combustion takes place, and how well it performs, is crucial for the operation of the entire control system. Existing research on gas-fired water heaters has primarily focused on determining whether the gas is ignited. A single-chip microcomputer measures the voltage detection signal provided by the flame detection circuit and determines whether the gas is ignited based on its voltage value and waveform. However, this method cannot determine the combustion status of the flame after ignition, resulting in wasted gas resources and impacting the efficiency of the gas water heater.

[0056] This application provides a flame detection circuit that adds a current detection scheme to the flame presence determination scheme. A low input voltage is converted into a high output square wave voltage through a boost circuit and a square wave circuit. This voltage is then provided by the current detection circuit, which calculates the detection current flowing through flame detection pin CN1. The flame combustion status is determined based on the detection current, and the flame detection circuit simultaneously determines whether discharge pin CN2 has been successfully ignited. This circuit not only ensures the accuracy of the circuit's flame detection, but also adds the ability to detect the magnitude of the current flowing through flame detection pin CN1. This allows the optimal gas-air mixture ratio to be determined, improving the operating efficiency of the gas water heater and avoiding gas energy waste.

[0057] Next, the technical solutions shown in this application are described in detail through specific embodiments. It should be noted that the following embodiments can exist independently or in combination with each other, and the same or similar contents will not be repeated in different embodiments.

[0058] Figure 1 This is a structural diagram of a flame combustion detection circuit provided in an embodiment of the present application. Figure 1 As shown, the flame combustion detection circuit includes a boost circuit, a square wave circuit, a current detection circuit and a flame detection circuit, wherein:

[0059] The output end of the boost circuit is connected to the input end of the square wave circuit, the output end of the square wave circuit is connected to the current detection circuit, and the current detection circuit is connected to the flame detection circuit through a single-pole double-throw relay K1;

[0060] The boost circuit is used to convert the input voltage into a high output voltage;

[0061] The square wave circuit is used to generate a square wave voltage composed of a positive voltage and a negative voltage to prevent the flame detection needle CN1 in the flame detection circuit from generating ionization;

[0062] The current detection circuit is used to provide a detection voltage to obtain a detection current flowing through the flame detection needle CN1 according to the detection voltage, and to obtain the optimal combustion condition of the flame according to the detection current;

[0063] The flame detection circuit is used to detect whether the flame is ignited.

[0064] The heat source of a gas-fired water heater comes from the combustion of gas. Whether and how well the combustion is performed is crucial to the operation of the entire control system. However, most existing technologies only consider the presence of a flame after ignition, using circuitry to determine when the water heater is in use. If the gas-air ratio is not appropriate, incomplete combustion can occur, reducing heating efficiency and wasting gas resources.

[0065] Furthermore, the more complete the gas combustion, the greater the flame ionization current, and thus the greater the detectable current. Therefore, this embodiment adds a current detection circuit for detecting the flame ionization current, which is connected to the flame detection circuit for detecting the presence of flame via a single-pole double-throw relay K1.

[0066] In this circuit, the flame detection circuit includes a boost circuit, a square wave circuit, a current detection circuit, and a flame detection circuit. Since the flame generated by gas combustion is detected via flame detection pin CN1, which is always under positive voltage and easily ionized, the input voltage is converted into a square wave voltage consisting of positive and negative voltages before the current detection circuit detects the flame ion current flowing through flame detection pin CN1. Specifically:

[0067] The boost circuit boosts the low input voltage and then uses a square-wave circuit to convert the boosted voltage into a square wave consisting of positive and negative voltages. The current detection circuit provides a detection voltage and, based on Hoff's current law, determines the detection current flowing through flame detection pin CN1. By monitoring the changes in the detection current, the maximum detection current is determined, and this maximum detection current is used to determine the optimal combustion conditions for the gas water heater flame.

[0068] Furthermore, after confirming the optimal combustion conditions of the gas water heater flame, the flame detection circuit is connected through the single-pole double-throw relay K1, and the flame detection circuit is used to determine whether the gas water heater is ignited normally, that is, whether there is a flame.

[0069] It should also be noted that if a heating gas water heater is used for an extended period or under certain special circumstances, the flame detection needle may become condensed with water droplets and impurities. If not promptly addressed and continued use, this can affect the operating efficiency of the heating gas water heater and, in serious cases, create safety hazards. In this embodiment, when condensed water droplets and impurities appear on the flame detection needle CN1, the flame detection needle CN1 may be unable to sense the flame, or the sensed flame may become unstable, causing the detection voltage captured by the microcontroller to fluctuate erratically under the same combustion conditions. Therefore, a timely alarm message can be sent to remind the user to take appropriate action.

[0070] This application provides a flame detection circuit that adds a current detection scheme to the flame presence determination scheme. A low input voltage is converted into a high output square wave voltage through a boost circuit and a square wave circuit. This voltage is then provided by the current detection circuit, which calculates the detection current flowing through flame detection pin CN1. The flame combustion status is determined based on the detection current, and the flame detection circuit simultaneously determines whether discharge pin CN2 has been successfully ignited. This circuit not only ensures the accuracy of the circuit's flame detection, but also adds the ability to detect the magnitude of the current flowing through flame detection pin CN1. This allows the optimal gas-air mixture ratio to be determined, improving the operating efficiency of the gas water heater and avoiding gas energy waste.

[0071] It should be noted that this embodiment does not impose any restrictions on the specifications of each component in the flame combustion detection circuit. However, to facilitate the description of subsequent embodiments, specific values ​​will be used for illustration.

[0072] Figure 2 This is a schematic diagram of the structure of a boost circuit provided in an embodiment of the present application. Figure 2 As shown, the boost circuit includes an inductor L1, a transistor N1, a diode D1, and an electrolytic capacitor E1:

[0073] The input end of the inductor L1 is connected to the first voltage source, the output end is connected to the anode of the diode D1 through one end of the resistor R4, and the other end is connected to the resistor R6 and then to the collector of the transistor N1;

[0074] The cathode of the diode D1 is grounded through the electrolytic capacitor E1;

[0075] The emitter of the transistor N1 is grounded, and the base is grounded via a pull-down resistor R20 . Meanwhile, the base of the transistor N1 is connected to a single chip microcomputer via a resistor R14 , so that the single chip microcomputer controls the conduction of the transistor N1 .

[0076] In this circuit, the inductor L1 is connected to the low input voltage, and the boost energy storage is completed under the control of the on or off state of the transistor N1, that is, the low input voltage is converted into a high voltage, and the electrolytic capacitor E1 is charged through the diode D1.

[0077] Furthermore, the transistor's on / off switching is controlled by a single-chip microcomputer (MCU), which is connected to the base of MOSFET N1. Since the circuit voltage is relatively high at this time, to prevent excessive voltage from being applied to the MCU, the MCU is connected to the base of MOSFET N1 via resistor R14, which acts as a pre-protection circuit. To ensure the switching efficiency of MOSFET N1, namely, to shorten the transition time between the MOSFET's off and on states, the base of MOSFET N1 is grounded via pull-down resistor R20. Pull-down resistor R20 ensures rapid discharge of the capacitance between the base and emitter of MOSFET N1, accelerating MOSFET N1's turn-off. Furthermore, as part of the protection circuit, the output end of inductor L1 is connected to resistor R4, which acts as a voltage divider and current limiter. Simultaneously, one end of resistor R4's output is connected to the collector of MOSFET N1 via resistor R6, which also acts as a voltage divider and current limiter.

[0078] At the same time, in order to prevent the voltage of the electrolytic capacitor E1 from being too high, a protection sub-circuit is added to the boost circuit. The connection method of the protection sub-circuit is as follows:

[0079] The cathode of the diode D1 is connected to the voltage-dividing resistor R8, the first output end of the voltage-dividing resistor R8 is grounded through the voltage-dividing resistor R28, and the second output end of the voltage-dividing resistor R8 is connected to the cathode of the voltage-stabilizing diode ZD3;

[0080] One end of the positive electrode of the voltage stabilizing diode ZD3 is grounded via the capacitor C4, and the other end is connected to the base of the band-stop transistor N3;

[0081] The collector of the band-stop transistor N3 is connected to the base of the transistor N1 , and the emitter of the band-stop transistor N3 is grounded.

[0082] When the voltage of the electrolytic capacitor E1 is too high and the base voltage of the band-stop transistor N3 exceeds the corresponding limit voltage, the base voltage of the transistor N1 is pulled down under the action of the protection sub-circuit, so that the boost function of the boost circuit is suspended and the voltage output to the electrolytic capacitor E1 is reduced.

[0083] This application provides a flame detection circuit that uses transistor N1's switching to boost and store energy through inductor L1, and then charges electrolytic capacitor E1 through diode D1. Furthermore, a subcircuit is included to forcibly lower the base voltage of transistor N1 when the voltage is too high, suspending the boost circuit's boost function and reducing the voltage output to electrolytic capacitor E1. This circuit converts a low input voltage into a high output voltage, which is then supplied to a square wave circuit to generate a square wave voltage. The protection subcircuit also provides output overvoltage protection.

[0084] Figure 3 This is a schematic diagram of the structure of a square wave circuit provided in an embodiment of the present application. Figure 3As shown, the square wave circuit includes transistor P1, capacitor C1, transistor N4, Zener diode ZD1 and Zener diode ZD2, where:

[0085] The emitter of the transistor P1 is connected to the output end of the boost circuit, the output end of the boost circuit is connected to the base of the transistor P1 through a pull-up resistor R7, and the base of the transistor P1 is connected to the collector of the transistor N4 through a voltage divider resistor R21;

[0086] The emitter of the transistor N4 is grounded, one end of the base is grounded via a pull-down resistor R33, and the other end is connected to the single chip microcomputer via a resistor R31, so that the single chip microcomputer controls the conduction of the transistor N4;

[0087] The capacitor C1 is connected to the collector of the transistor P1 through the current limiting resistor R17, and the collector of the transistor P1 is grounded through the load resistor R26. At the same time, the first output end of the capacitor C1 is connected in series with the cathode of the Zener diode ZD1 and the anode of the Zener diode ZD2 and grounded.

[0088] In this circuit, the microcontroller controls the on and off of transistor N4, thereby controlling the switch of transistor P1, that is, the on and off of transistor P1. The output voltage of the boost circuit is then converted into a square wave voltage consisting of positive and negative voltages through capacitor C1.

[0089] It should be noted that the single chip microcomputer connected to the flame combustion detection circuit is the same single chip microcomputer, and different circuits are connected to different interfaces on the single chip microcomputer.

[0090] Furthermore, to ensure the working state of transistors P1 and N4 and accelerate their cutoff, the base of transistor P1 is connected to the boost circuit via pull-up resistor R7, while the base of transistor N4 is grounded via pull-down resistor R23. To prevent excessive voltage from reaching the microcontroller, resistor R31 is added between the base of transistor N4 and the microcontroller to provide pre-circuit protection.

[0091] At the same time, the voltage distributed to the emitter of transistor P1 is 130V. In order to generate +51V and -36V square wave voltages after capacitor C1 and protect the circuit, load resistor R26 and current limiting resistor R17 are added. One end of the collector of transistor P1 is grounded through load resistor R26, and the other end is connected to capacitor C1 through current limiting resistor R17.

[0092] Furthermore, to ensure that the square wave voltage generated after capacitor C1 is a stable +51V positive voltage and -36V negative voltage, Zener diodes ZD1 and ZD2 are added. The first output terminal of capacitor C1 is connected in series with the cathode of Zener diode ZD1 and the anode of Zener diode ZD2, and then grounded. Zener diode ZD1 corresponds to a positive voltage of +51V, while Zener diode ZD2 corresponds to a negative voltage of -36V.

[0093] This application provides a flame detection circuit that uses a single-chip microcomputer to control the on / off switching of transistor N4, thereby controlling the switching of transistor P1. Capacitor C1 then converts the output voltage of the boost circuit into a square wave consisting of positive and negative voltages. This circuit converts the output voltage of the boost circuit into a stable square wave voltage, preventing ionization of the flame detection pin CN1 and protecting the circuit.

[0094] Figure 4 This is a schematic diagram of the structure of a current detection circuit provided in an embodiment of the present application. Figure 4 As shown, the current detection circuit includes a voltage divider resistor R5, a current limiting resistor R1, a voltage divider resistor R3, a measuring resistor R24 ​​and a second voltage source, wherein:

[0095] The voltage divider resistor R5 is connected in series with the current limiting resistor R18 and the single chip microcomputer via one end of the second intersection to determine whether the square wave circuit generates a square wave voltage, and is connected to the first parallel circuit consisting of the capacitor C2 and the resistor R23 via the other end of the second intersection;

[0096] The current limiting resistor R1 is connected to the first contact of the single-pole double-throw relay K1 through the third intersection, and is also connected to the voltage divider resistor R3 through the third intersection. The measuring resistor R24 ​​is connected in series with the flame detection needle CN2 and then in parallel with the capacitor C3 to form a second parallel circuit. The first parallel circuit is grounded through the second parallel circuit.

[0097] The voltage dividing resistor R3 is connected to the second parallel circuit via a fourth intersection, and is also connected in series with the current limiting resistor R19 and the single chip microcomputer via the fourth intersection to provide a detection voltage corresponding to the measuring resistor R24;

[0098] The square wave circuit is connected to the current limiting resistor R1 at one end through the first intersection and to the voltage divider resistor R5 at the other end. Meanwhile, the second voltage source is connected to the first parallel circuit through the resistor R11 and to the second parallel circuit through the resistor R12.

[0099] In this circuit, it should be noted that 1, 2, 3 and 4 in the circuit diagram correspond to the first intersection, the second intersection, the third intersection and the fourth intersection respectively, and the +5V voltage in this circuit diagram corresponds to the second voltage source.

[0100] Specifically, the circuit consisting of voltage-dividing resistor R5, resistor R23, current-limiting resistor R18, and resistor R11 is used to detect the square wave circuit. Current-limiting resistor R18 is connected to the microcontroller. The voltage signal read by the microcontroller determines whether there are two stable positive and negative voltages. The square wave circuit is then verified based on the result of this determination. If the voltage signal from the microcontroller determines that the square wave circuit is not generated, a fault is reported.

[0101] The square wave voltage is a positive voltage of +51V and a negative voltage of -36V. To avoid damaging the microcontroller, the voltage divider resistor R5, resistor R23, current limiting resistor R18, and resistor R11 act as voltage divider and current limiting protection. The capacitor C2 connected in parallel with resistor R23 acts as a filter.

[0102] Furthermore, the circuit part composed of the current limiting resistor R1, the voltage dividing resistor R3, the measuring resistor R24, the resistor R12 and the current limiting resistor R19 is used to provide a detection voltage, based on which the detection current flowing through the flame detection needle CN1 is calculated.

[0103] Specifically, the microcontroller is connected to the second parallel circuit via current-limiting resistor R19, which provides protection. The detection voltage read by the microcontroller is the voltage across current-limiting resistor R19. Since the current-limiting resistor is connected to the second parallel circuit via the fourth intersection, the detection voltage is also the voltage across measuring resistor R24. In the second parallel circuit, flame detection pin CN2 forms a loop, and capacitor C3 provides filtering.

[0104] At the same time, in order to protect the safety of the single chip microcomputer, voltage dividing and current limiting protection is performed through the current limiting resistor R1, the voltage dividing resistor R3 and the resistor R12.

[0105] For example, the current limiting resistor R1 is 800KΩ, the voltage dividing resistor R3 is 1220KΩ, the measuring resistor R24 ​​is 220KΩ, the resistor R12 is 270KΩ, the detection voltage is V, and the positive voltage in the square wave voltage accounts for 0.3. The specific calculation process is:

[0106] The current I4 flowing through the detection resistor R24 ​​is derived from the current I3 flowing through the voltage divider resistor R3 and the current provided by the second voltage source, so I3 = V / 220-(5-V) / 270;

[0107] Calculate the voltage U3 of the voltage divider resistor R3 based on the current I3, and get: U3=I3*R3=[V / 220-(5-V) / 270]*1220;

[0108] The voltage U at the third intersection includes the voltage U3 and the detection voltage corresponding to the measuring resistor R24, so: U=U3+V=[V / 220-(5-V) / 270]*1220+V;

[0109] The voltage U1 distributed to the current-limiting resistor R1 is the difference between the positive voltage of the square wave voltage and the voltage U at the third intersection, which is: U1 = 51-[V / 220-(5-V) / 270]*1220-V. Therefore, the current I1 flowing through the current-limiting resistor R1 is: I1 = U1 / R1 = [51-[V / 220-(5-V) / 270]*1220-V] / 800;

[0110] Based on Kirchhoff's current law, the current I1 flowing through the current limiting resistor R1 is the sum of the current I3 flowing through the voltage divider resistor R3 and the current I flowing through the flame detection needle CN1. Therefore, [51-[V / 220-(5-V) / 270]*1220-V] / 800=I+[V / 220-(5-V) / 270], I=(110.5-22.08V).

[0111] Finally, since the positive voltage accounts for 0.3 in the square wave voltage, the final detection current I 检 Calculated: I 检 =0.3*(110.5-22.08V).

[0112] This application provides a flame detection circuit. Based on Kirchhoff's laws, this circuit infers the detection current flowing through flame detection pin CN1 from the detection voltage obtained by a single-chip microcomputer. The circuit then determines the combustion conditions corresponding to optimal combustion based on the changes in the detection current. This circuit achieves an optimal gas-air mixture ratio, thereby improving the operating efficiency of a gas water heater.

[0113] Figure 5 This is a structural diagram of a flame detection circuit provided in an embodiment of the present application. Figure 5 As shown, the flame detection circuit includes the flame detection needle CN1, a self-excited oscillation sub-circuit and a flame detection sub-circuit, wherein:

[0114] The input end of the flame detection needle CN1 is connected to the second contact of the single-pole double-throw relay K1, and is connected to the self-excited oscillation sub-circuit at one end and the flame detection sub-circuit at the fifth node through the resistor R30.

[0115] Generally, the presence of a flame can be determined directly based on the current flowing through the flame detection needle. However, when the flame detection needle is fouled and oxidized, the difference in the magnitude of the current flowing through the flame detection needle with or without a flame is very small. Therefore, it is not accurate to directly determine whether the gas water heater is ignited based on the detection current flowing through the flame detection needle CN1. Therefore, this embodiment determines the presence of a flame based on the flame detection circuit.

[0116] Furthermore, the self-excited oscillation subcircuit is used to perform an ignition operation, and the flame detection subcircuit is used to provide a voltage signal so as to determine whether the gas water heater is successfully ignited at this time based on the continuous voltage signal.

[0117] Similarly, the corresponding Figure 5 Among them, 5, 6, 7 and 8 correspond to the 5th intersection, 6th intersection, 7th intersection and 8th intersection respectively.

[0118] Specifically, the flame detection sub-circuit includes a voltage divider resistor R34, a third voltage source, a fourth voltage source and a pull-up resistor R32, wherein:

[0119] The input end of the voltage divider resistor R34 is connected to the fifth node, the output end is connected to the anode of the diode D3 and the third voltage source in sequence through the sixth node, one end is connected to the cathode of the diode D4 and then to ground, and the other end is connected to the resistor R35, the resistor R36 and the single chip microcomputer in sequence;

[0120] The fourth voltage source is connected between the resistor R35 and the resistor R36 via the pull-up resistor R32 . The resistor R36 and the microcontroller are grounded via the capacitor C6 . Meanwhile, the voltage divider resistor R34 and the resistor R35 are grounded via the capacitor C5 .

[0121] To protect the microcontroller, resistor R36 is connected to the microcontroller. Voltage divider resistors R34 and R35 act as voltage dividers, while diodes D3 and D4 provide pre-circuit protection. After pre-processing, the voltage is nearly zero. If read directly from the microcontroller, it would be impossible to determine whether the gas water heater is ignited. Therefore, pull-up resistor R32 is used to increase the voltage amplitude so that waveform changes can be identified based on the voltage signal.

[0122] Furthermore, in the self-oscillation sub-circuit, the self-oscillation sub-circuit includes a transistor P2, a transistor N5 and a transformer T1, wherein:

[0123] Pin 6 of the secondary of the transformer T1 is grounded, one end of pin 5 is connected to the fifth intersection via a current-limiting resistor R37 and a capacitor C7, the other end of pin 5 is connected to the anode of a diode D5, the cathode of the diode D5 is connected to a discharge resistor R38 at one end through the seventh intersection and then to ground, and the other end is connected to pin 1 of the primary of the transformer T2 via a capacitor C8, the cathode of the diode D5 and the capacitor C8 are grounded via a voltage-stabilizing diode D6, and pin 2 of the primary of the transformer T2 is grounded, and a discharge pin CN8 is connected between pins 3 and 4 of the secondary;

[0124] Pin 3 of the main winding of the transformer T1 is connected to a fifth voltage source, and pin 2 is connected to the collector of the transistor N5. Pin 4 of the trigger winding of the transformer T1 is connected to a discharge resistor R40 at one end through an eighth intersection and then to the emitter of the transistor P2. The other end is connected to a discharge resistor R45 and then to the collector of the transistor P2. The base of the transistor P2 is connected to the microcontroller via a current-limiting resistor R42 to control the conduction of the transistor P2, and is connected to a sixth voltage source via a pull-up resistor R39. The emitter of the transistor P2 is also connected between the resistor R39 and the sixth voltage source.

[0125] Pin 1 of the trigger winding of the transformer T1 is connected to the input end of the discharge resistor R41. One end of the output end of the discharge resistor R41 is connected to the base of the transistor N5 and the other end is grounded through the capacitor C9. At the same time, the emitter of the transistor N5 is grounded.

[0126] The microcontroller is connected to the base of transistor P2 via current-limiting resistor R42 and is used to control the conduction of transistor P2. To ensure the working state of transistor P2 and accelerate the cutoff of transistor P2, the base of transistor P2 is connected to the sixth voltage source via pull-up resistor R39.

[0127] Furthermore, transistor P2 is used to connect discharge resistor R40 and discharge resistor R45 in parallel.

[0128] Capacitor C7 blocks DC from passing AC, while current-limiting resistor R37 provides protection and current limiting. When the microcontroller controls transistor P2 to saturate and conduct, discharge resistor R40 is short-circuited. Transformers T1 and T2 operate together, causing the secondary of transformer T2 to output a high voltage. Discharge pin CN8, connected between pins 3 and 4 of the secondary of transformer T2, discharges and ignites the gas. At this point, the flame creates a diode effect, and the microcontroller detects more negative than positive signals in the AC signal, detecting a low level.

[0129] If the MCU controls transistor P2 to be turned off, discharging resistor R45 is disconnected. Although both transformers T1 and T2 amplify the voltage, the voltage output from the secondary of transformer T2 is insufficient to ignite the gas water heater. At this point, the positive and negative signals in the AC signal obtained by the MCU are symmetrical, and a high level is detected.

[0130] At the same time, diode D5 is used to convert AC into DC, and discharge resistor R38 is used to discharge capacitor C8. Considering that capacitor C8 needs to discharge quickly when the flame is ignited, the discharge process through discharge resistor R38 is slow. Therefore, capacitor C8 is discharged through Zener diode D6. When the flame is ignited, the high voltage turns on Zener diode D6, and discharges quickly.

[0131] This application provides a flame detection circuit that uses an oscillation excitation subcircuit to perform ignition operations and simultaneously determines whether a gas water heater has been successfully ignited based on the flame detection subcircuit. This circuit can quickly detect the presence of a flame in a gas water heater under abnormal conditions such as oxidation of the flame detection needle, increasing the accuracy of the determination.

[0132] Figure 6 This is a circuit diagram of a single-pole double-throw relay connection provided in an embodiment of the present application. Figure 6 As shown, the input end of the single-pole double-throw relay K1 is connected to the seventh voltage source, the output end is connected to the collector of the transistor N2, the voltage regulator diode D2 is connected in parallel with the single-pole double-throw relay K1, and the emitter of the transistor N2 is grounded. One end of the base is connected to the single-chip microcomputer through the resistor R22 to control the conduction of the transistor N2, and one end is grounded through the pull-down resistor R29.

[0133] In this circuit, transistor N2 acts as a switch to control single-pole, double-throw relay K1. The microcontroller controls the on / off state of transistor N2. Similarly, to protect the microcontroller, resistor R22 connects the microcontroller to the base of transistor N2. To accelerate transistor N2's turn-off, the base of transistor N2 is grounded via pull-down resistor R29. Zener diode D2 provides freewheeling.

[0134] This application provides a flame detection circuit that switches the flame detection circuit's functions by controlling the conduction of transistor N2 through a single-pole, double-throw relay K1. This circuit can detect the presence of a flame in a gas water heater and determine the optimal gas-to-air ratio based on the detected current, thereby ensuring the heater's operating efficiency.

[0135] Figure 7 The flowchart of a method for confirming the opening of a servo motor provided in an embodiment of the present application is shown in FIG. Figure 7 As shown, the method includes:

[0136] S701. When the gas water heater is installed for the first time, the gas output is adjusted by adjusting the opening of the servo motor of the gas water heater and the detection voltage corresponding to the measuring resistor R24 ​​detected by the single chip microcomputer is continuously obtained.

[0137] In this step, when a new appliance is installed or the gas source is changed, gas matching is required. Gas matching aims to achieve an optimal ratio of air to gas, ensuring complete combustion and maximum thermal efficiency. When the gas is fully combusted, the current flowing through the flame detector needle is maximum. Therefore, this embodiment determines the optimal gas-air mixture ratio based on the continuous changes in the detection current.

[0138] Furthermore, the gas intake of the gas water heater is controlled by adjusting the opening of the servo motor. Therefore, when the gas water heater is first installed, the opening of the servo motor is adjusted to adjust the gas output. At the same time, the detection voltage corresponding to the measuring resistor R24 ​​obtained by the single chip microcomputer is recorded.

[0139] S702 : Calculate the detection current corresponding to the flame detection needle CN1 according to the detection voltage based on a preset calculation relationship.

[0140] In this step, the preset calculation relationship is determined according to the resistance values ​​of the measuring resistor R24, the voltage dividing resistor R3 and the current limiting resistor R1.

[0141] Specifically, after a plurality of detection voltages are obtained, the detection current corresponding to each detection voltage is obtained according to a preset calculation relationship calculated in advance.

[0142] S703 , obtaining a target detection current with a maximum value from the multiple detection currents, obtaining a target opening of the servo motor corresponding to the target detection current, and adjusting the opening of the servo motor according to the target opening.

[0143] In this step, since the servo motor opening of the gas water heater has a range requirement, the target detection current with the largest value exists in the obtained detection current. Since the above embodiment has detailed how to obtain the preset calculation relationship, this embodiment will not be further described.

[0144] Specifically, after obtaining multiple detection currents based on a preset calculation relationship, the multiple detection currents are sorted in descending order, and a target detection current is obtained based on the detection current corresponding to the first position. The opening of the servo motor corresponding to the target detection current is the required target opening. After obtaining the target opening, the servo motor is adjusted according to the target opening.

[0145] For example, the preset calculation relationship is: I = 0.3 (110.5-22.08V), and the multiple detection voltages obtained continuously are V1 = 0.8V, V2 = 2V, V3 = 1.6V, V4 = 2.6V, V5 = 3.2V, and V6 = 3V. The corresponding openings are K1 = 0.2, K2 = 0.33, K3 = 0.26, K4 = 0.45, K5 = 0.44, and K6 = 0.39. According to the preset calculation relationship, I1 = 27.85, I2 = 19.9, I3 = 22.55, I4 = 15.92, I5 = 11.95, and I6 = 13.28 are obtained. The maximum detection current is I1 = 22.85, so the target opening is K1 = 0.2.

[0146] This application provides a method for determining the opening of a servo motor. When a gas water heater is installed, the gas delivery rate is adjusted by adjusting the opening of the servo motor, and the corresponding detection voltage changes are recorded. The electrical current corresponding to each detection voltage is calculated. The target opening for the optimal combustion condition is obtained based on the numerical values ​​of the multiple electrical currents, and the servo motor opening is adjusted accordingly. Through this method, the optimal gas-air ratio is obtained based on the changes in the detection current, thereby improving the operating efficiency of the gas water heater and avoiding gas energy waste.

[0147] The present application also provides a computer storage medium, in which computer execution instructions are stored. When a processor executes the computer execution instructions, the technical solution of the above-mentioned service motor opening confirmation method is implemented.

[0148] The computer-readable storage medium may be implemented by any type of volatile or non-volatile memory device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The computer-readable storage medium may be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0149] An exemplary readable storage medium is coupled to a processor, so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an application-specific integrated circuit (ASIC). Of course, the processor and the readable storage medium can also exist as discrete components in the control device of the clothing processing device.

[0150] The division of units described above is merely a logical functional division. In actual implementation, other divisions may be employed. For example, multiple units or components may be combined or integrated into another system, or some features may be omitted or not implemented. Furthermore, any coupling or direct coupling or communication connection shown or discussed between units may be an indirect coupling or communication connection via an interface, device, or unit, and may be electrical, mechanical, or other.

[0151] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0152] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0153] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0154] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps in the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0155] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the scope of protection of the present application is obviously not limited to these specific embodiments. The above embodiments are only used to illustrate the technical solution of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A flame combustion detection circuit, characterized in that: The circuit includes a boost circuit, a square wave circuit, a current detection circuit and a flame detection circuit, wherein: The output end of the boost circuit is connected to the input end of the square wave circuit, the output end of the square wave circuit is connected to the current detection circuit, and the current detection circuit is connected to the flame detection circuit through a single-pole double-throw relay K1; The boost circuit is used to convert the input voltage into a high output voltage; The square wave circuit is used to generate a square wave voltage composed of a positive voltage and a negative voltage to prevent the flame detection needle CN1 in the flame detection circuit from generating ionization; The current detection circuit is used to provide a detection voltage to obtain a detection current flowing through the flame detection needle CN1 according to the detection voltage, and to obtain an optimal combustion condition of the flame according to the detection current; The flame detection circuit is used to detect whether the flame is ignited.

2. The circuit according to claim 1, wherein: The boost circuit includes an inductor L1, a transistor N1, a diode D1, and an electrolytic capacitor E1: The input end of the inductor L1 is connected to the first voltage source, the output end is connected to the anode of the diode D1 through one end of the resistor R4, and the other end is connected to the resistor R6 and then to the collector of the transistor N1; The cathode of the diode D1 is grounded through the electrolytic capacitor E1; The emitter of the transistor N1 is grounded, and the base is grounded via a pull-down resistor R20 . Meanwhile, the base of the transistor N1 is connected to a single chip microcomputer via a resistor R14 , so that the single chip microcomputer controls the conduction of the transistor N1 .

3. The circuit according to claim 2, characterized in that The boost circuit further includes a protection sub-circuit, which includes a voltage divider resistor R8, a voltage divider resistor R28, a voltage stabilizing diode ZD3, and a band-blocking transistor N3, wherein: The cathode of the diode D1 is connected to the voltage-dividing resistor R8, the first output end of the voltage-dividing resistor R8 is grounded through the voltage-dividing resistor R28, and the second output end of the voltage-dividing resistor R8 is connected to the cathode of the voltage-stabilizing diode ZD3; One end of the positive electrode of the voltage stabilizing diode ZD3 is grounded via the capacitor C4, and the other end is connected to the base of the band-stop transistor N3; The collector of the band-stop transistor N3 is connected to the base of the transistor N1 , and the emitter of the band-stop transistor N3 is grounded.

4. The circuit according to claim 3, characterized in that The square wave circuit includes transistor P1, capacitor C1, transistor N4, Zener diode ZD1 and Zener diode ZD2, wherein: The emitter of the transistor P1 is connected to the output end of the boost circuit, the output end of the boost circuit is connected to the base of the transistor P1 through a pull-up resistor R7, and the base of the transistor P1 is connected to the collector of the transistor N4 through a voltage divider resistor R21; The emitter of the transistor N4 is grounded, one end of the base is grounded via a pull-down resistor R33, and the other end is connected to the single chip microcomputer via a resistor R31, so that the single chip microcomputer controls the conduction of the transistor N4; The capacitor C1 is connected to the collector of the transistor P1 through the current limiting resistor R17, and the collector of the transistor P1 is grounded through the load resistor R26. At the same time, the first output end of the capacitor C1 is connected in series with the cathode of the Zener diode ZD1 and the anode of the Zener diode ZD2 and grounded.

5. The circuit according to claim 4, characterized in that The current detection circuit includes a voltage dividing resistor R5, a current limiting resistor R1, a voltage dividing resistor R3, a measuring resistor R24, and a second voltage source, wherein: The voltage divider resistor R5 is connected in series with the current limiting resistor R18 and the single chip microcomputer via one end of the second intersection to determine whether the square wave circuit generates a square wave voltage, and is connected to the first parallel circuit consisting of the capacitor C2 and the resistor R23 via the other end of the second intersection; The current limiting resistor R1 is connected to the first contact of the single-pole double-throw relay K1 through the third intersection, and is also connected to the voltage divider resistor R3 through the third intersection. The measuring resistor R24 ​​is connected in series with the flame detection needle CN2 and then in parallel with the capacitor C3 to form a second parallel circuit. The first parallel circuit is grounded through the second parallel circuit. The voltage dividing resistor R3 is connected to the second parallel circuit via a fourth intersection, and is also connected in series with the current limiting resistor R19 and the single chip microcomputer via the fourth intersection to provide a detection voltage corresponding to the measuring resistor R24; The square wave circuit is connected to the current limiting resistor R1 at one end through the first intersection and to the voltage divider resistor R5 at the other end. Meanwhile, the second voltage source is connected to the first parallel circuit through the resistor R11 and to the second parallel circuit through the resistor R12.

6. The circuit according to claim 5, characterized in that The flame detection circuit includes the flame detection needle CN1, a self-excited oscillation sub-circuit and a flame detection sub-circuit, wherein: The input end of the flame detection needle CN1 is connected to the second contact of the single-pole double-throw relay K1, and is connected to the self-excited oscillation sub-circuit at one end and the flame detection sub-circuit at the fifth node through the resistor R30.

7. The circuit according to claim 6, characterized in that The flame detection sub-circuit comprises a voltage divider resistor R34, a third voltage source, a fourth voltage source and a pull-up resistor R32, wherein: The input end of the voltage divider resistor R34 is connected to the fifth node, the output end is connected to the anode of the diode D3 and the third voltage source in sequence through the sixth node, one end is connected to the cathode of the diode D4 and then to ground, and the other end is connected to the resistor R35, the resistor R36 and the single chip microcomputer in sequence; The fourth voltage source is connected between the resistor R35 and the resistor R36 via the pull-up resistor R32 . The resistor R36 and the microcontroller are grounded via the capacitor C6 . Meanwhile, the voltage divider resistor R34 and the resistor R35 are grounded via the capacitor C5 .

8. The circuit according to claim 7, characterized in that The self-oscillation sub-circuit includes transistor P2, transistor N5 and transformer T1, wherein: Pin 6 of the secondary of the transformer T1 is grounded, one end of pin 5 is connected to the fifth intersection via a current-limiting resistor R37 and a capacitor C7, the other end of pin 5 is connected to the anode of a diode D5, the cathode of the diode D5 is connected to a discharge resistor R38 at one end through the seventh intersection and then to ground, and the other end is connected to pin 1 of the primary of the transformer T2 via a capacitor C8, the cathode of the diode D5 and the capacitor C8 are grounded via a voltage-stabilizing diode D6, and pin 2 of the primary of the transformer T2 is grounded, and a discharge pin CN8 is connected between pins 3 and 4 of the secondary; Pin 3 of the main winding of the transformer T1 is connected to a fifth voltage source, and pin 2 is connected to the collector of the transistor N5. Pin 4 of the trigger winding of the transformer T1 is connected to a discharge resistor R40 at one end through an eighth intersection and then to the emitter of the transistor P2. The other end is connected to a discharge resistor R45 and then to the collector of the transistor P2. The base of the transistor P2 is connected to the microcontroller via a current-limiting resistor R42 to control the conduction of the transistor P2, and is connected to a sixth voltage source via a pull-up resistor R39. The emitter of the transistor P2 is also connected between the resistor R39 and the sixth voltage source. Pin 1 of the trigger winding of the transformer T1 is connected to the input end of the discharge resistor R41. One end of the output end of the discharge resistor R41 is connected to the base of the transistor N5 and the other end is grounded through the capacitor C9. At the same time, the emitter of the transistor N5 is grounded.

9. The circuit according to any one of claims 1 to 8, characterized in that: The input end of the single-pole double-throw relay K1 is connected to the seventh voltage source, the output end is connected to the collector of the transistor N2, the voltage regulator diode D2 is connected in parallel with the single-pole double-throw relay K1, and the emitter of the transistor N2 is grounded. One end of the base is connected to the single-chip microcomputer through the resistor R22 to control the conduction of the transistor N2, and one end is grounded through the pull-down resistor R29.

10. A method for confirming the opening of a servo motor, characterized in that: Applied to the circuit according to any one of claims 1 to 9, the method comprises: When the gas water heater is installed for the first time, the gas output is adjusted by adjusting the opening of the servo motor of the gas water heater and the detection voltage corresponding to the measuring resistor R24 ​​detected by the single chip microcomputer is continuously obtained; Calculating the detection current corresponding to the flame detection needle CN1 according to the detection voltage based on a preset calculation relationship, wherein the preset calculation relationship is determined according to the resistance values ​​of the measuring resistor R24, the voltage dividing resistor R3, and the current limiting resistor R1; A target detection current with the largest value is obtained from a plurality of detection currents, a target opening of the servo motor corresponding to the target detection current is obtained, and the opening of the servo motor is adjusted according to the target opening.

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