Ignition and flame detection circuit and gas water heater
By combining the output circuit of the flame detection circuit with that of the ignition circuit, and using the high-voltage output terminal for flame detection, the problems of excessive wiring and high hardware cost in traditional flame detection circuits are solved, achieving seamless integration of flame detection and ignition and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-21
- Publication Date
- 2026-03-31
AI Technical Summary
Traditional flame detection circuits require flame probes, resulting in extensive wiring and high hardware costs.
The self-excited oscillation circuit is combined with the output circuit of the ignition circuit. The high voltage output terminal of the ignition circuit is used to detect the flame in the combustion area. The flame detection is achieved through the diode effect, eliminating the need for an additional flame probe.
It achieves a seamless integration of flame detection and ignition functions, reducing wiring and hardware costs while maintaining high-efficiency flame detection.
Smart Images
Figure CN224065696U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of circuits, and more specifically, to an ignition and flame detection circuit, and a gas water heater using the same. Background Technology
[0002] With the improvement of people's living standards, more and more ignition devices have emerged, such as wall-mounted boilers, gas stoves, and gas water heaters. After ignition, these devices can be used for cooking or heating water using the heat generated by ignition, greatly improving the convenience of people's lives. In order to improve the working performance of ignition devices, it is necessary to detect the flame of the ignition devices so that corresponding measures can be taken in time when the flame is abnormally extinguished to avoid safety hazards.
[0003] Traditional flame detection circuits require a flame probe and three wires: two high-voltage ignition wires and one flame detection wire. The flame detection wire is connected to the flame probe, and different signals are generated based on whether a flame is present, which are then output to the control module. This detection method involves a lot of wiring, which is inconvenient for routing and has high hardware costs. Summary of the Invention
[0004] To address the technical problems of existing flame detection methods that require flame probes, resulting in extensive wiring and high hardware costs, this invention proposes an ignition and flame detection circuit that solves these issues.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0006] An ignition and flame detection circuit, comprising:
[0007] The self-excited oscillation circuit is used to receive the ignition control signal and generate an oscillation signal by oscillation.
[0008] An ignition circuit, comprising an input circuit and an output circuit, wherein the input circuit receives the oscillation signal and the output circuit is used to release high voltage to ignite the gas.
[0009] A flame detection circuit is provided, wherein one of its input terminals is connected to the output terminal of the self-excited oscillation circuit, and the other is connected to the output circuit of the ignition circuit. The second terminal of the secondary winding of the first transformer is connected to the second terminal of the ignition circuit. The flame detection circuit generates and outputs a flame detection signal.
[0010] In some embodiments, the self-excited oscillation circuit includes a first transformer, one end of the first primary winding of the first transformer is connected to a DC power supply, and the other end is connected to ground through a first switch. One path of one end of the second primary winding of the first transformer is connected to a DC power supply, and the second path is connected to a DC power supply through a second switch. The other end of the second primary winding of the first transformer is connected to the control terminal of the first switch. The secondary winding of the first transformer is used to output an oscillation signal.
[0011] The control terminal of the second switch is used to receive ignition control signals.
[0012] In some embodiments, the first switch includes an NPN transistor, the base of which is connected to the second primary winding of the first transformer, the collector of which is connected to the first primary winding of the first transformer, and the emitter of which is connected to ground.
[0013] In some embodiments, the second switching circuit includes a PNP transistor, the base of which is used to receive an ignition control signal, the emitter of which is connected to a DC power supply, and the collector of which is connected to the second primary winding of the first transformer.
[0014] In some embodiments, the ignition circuit includes a second transformer, the primary winding of which is used to receive the oscillation signal, and the two ends of the secondary winding of the second transformer are a high-voltage output terminal and a high-voltage return terminal, respectively. The high-voltage output terminal is located in the combustion area. The secondary winding of the second transformer generates high-voltage electricity according to the oscillation signal and outputs it through the high-voltage output terminal.
[0015] In some embodiments, one end of the secondary winding of the first transformer is connected to the primary winding of the second transformer, and the other end is grounded. One input of the flame detection circuit is connected between the secondary winding of the first transformer and the primary winding of the second transformer, and the other input of the flame detection circuit is connected to the high-voltage return terminal.
[0016] In some embodiments, a discharge tube is also connected between the input terminal of the flame detection circuit and the high-voltage return terminal, and the other end of the discharge tube is connected to ground.
[0017] In some embodiments, a sixth resistor is connected between the first path of one end of the second primary winding of the first transformer and the DC power supply.
[0018] In some embodiments, the flame detection circuit includes:
[0019] A clamping circuit, which is connected to the input terminal of the flame detection circuit;
[0020] A filter circuit, which is connected to the clamping circuit;
[0021] An isolation circuit is connected between the output terminals of the filter circuit and the flame detection circuit.
[0022] In some embodiments, the isolation circuit includes an NMOS transistor, the gate of which is connected to the output of the filter circuit, the source of which is connected to ground, the drain of which is connected to a DC power supply, and the output of the flame detection circuit is connected to the drain of the NMOS transistor.
[0023] This utility model also proposes a gas water heater, including a control module that can generate and send ignition control signals, and also includes the ignition and flame detection circuit described in any of the preceding paragraphs.
[0024] Compared with existing technologies, the advantages and positive effects of this invention are as follows: The ignition and flame detection circuit of this invention connects the flame detection circuit to the output circuit of the ignition circuit. The flame detection function utilizes the fact that one end (high-voltage output terminal) of the ignition circuit's output circuit is located within the combustion zone. When the high-voltage output terminal outputs high voltage, it is used to ignite the gas. When the gas burns with a flame, the output circuit of the ignition circuit forms a diode effect, pulling down the voltage of the flame detection circuit, thus making the flame detection circuit effective. The flame detection and ignition functions do not interfere with each other, and this solution eliminates the need for a flame probe, reducing wiring and lowering hardware costs.
[0025] Other features and advantages of this utility model will become clearer after reading the detailed description of the embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description
[0026] Figure 1 This is a circuit diagram of one embodiment of the ignition and flame detection circuit proposed in this utility model. Detailed Implementation
[0027] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.
[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0029] It should be noted that in the description of this invention, terms such as "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.
[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0031] Example 1: This example proposes an ignition and flame detection circuit, see [link to example]. Figure 1 As shown, the circuit includes a self-excited oscillation circuit, an ignition circuit, and a flame detection circuit. The self-excited oscillation circuit receives the ignition control signal FIRE and oscillates to generate an oscillation signal. The ignition circuit includes an input circuit and an output circuit. The input circuit receives the oscillation signal, and the output circuit generates and releases high-voltage electricity based on the oscillation signal to ignite the combustion gas. One input terminal of the flame detection circuit is connected to the output terminal of the self-excited oscillation circuit, and the other is connected to the output circuit of the ignition circuit. The flame detection circuit generates and outputs a flame detection signal.
[0032] It is understandable that at least one end of the output circuit of the ignition circuit is located within the combustion zone. In this embodiment, the ignition and flame detection circuit connects the flame detection circuit to the output circuit of the ignition circuit. The flame detection function utilizes the fact that one end (the high-voltage output terminal) of the ignition circuit's output circuit is located within the combustion zone. When the high-voltage output terminal outputs high voltage, it is used to ignite the gas. When the gas burns with a flame, the output circuit of the ignition circuit forms a diode effect, pulling down the voltage of the flame detection circuit, thus making the flame detection circuit effective. This solution eliminates the need for a flame probe, reduces wiring, lowers hardware costs, and ensures that the flame detection and ignition functions do not interfere with each other.
[0033] In some embodiments, such as Figure 1As shown, the self-excited oscillation circuit includes a first transformer T1, a first switch, and a second switch. One end (end 7) of the first primary winding of the first transformer T1 is connected to the DC power supply VCC, and the other end (end 9) is connected to ground through the first switch. One end (end 10) of the second primary winding of the first transformer T1 has a first path connected to the DC power supply VCC through the sixth resistor R6, and a second path connected to the DC power supply VCC through the second switch. The other end (end 6) of the second primary winding of the first transformer T1 is connected to the control terminal of the first switch.
[0034] The secondary winding of the first transformer T1 can generate and output an oscillation signal according to the ignition control signal FIRE.
[0035] The control terminal of the second switch is used to receive the ignition control signal FIRE, and its conduction state is controlled by the ignition control signal FIRE.
[0036] In some embodiments, such as Figure 1 As shown, terminal 6 of the second primary winding of the first transformer T1 is connected to ground via resistor R15 (15th resistor) and capacitor C6 (6th capacitor). When not ignited, the ignition control signal FIRE is high, the second switch is not turned on, and the DC power supply VCC is supplied to the second primary winding of the first transformer T1 through resistor R6. R15 and C6 form a low-frequency resonant circuit to control the on / off state of the first switch. This low-frequency resonant circuit also causes current to flow in the primary winding of the first transformer T1. The secondary winding of the first transformer T1 then senses the changing voltage, resulting in a sinusoidal AC waveform at terminal 2 of the first transformer T1. Since the maximum value of this waveform does not exceed 200V, it cannot trigger diode D4 to conduct, thus preventing ignition. Without a flame, the positive and negative waveforms of the output waveform of the first transformer T1 are symmetrical and equal, canceling each other out after filtering, resulting in a voltage level of 0. When there is a flame, the combustion of the flame generates a flame ion current, which creates a diode effect. This pulls down the sine wave output from the secondary winding of the first transformer T1, resulting in more negative waveforms than positive waveforms. After filtering, the negative waveforms outnumber the positive waveforms, resulting in a negative voltage level. The flame detection circuit detects the flame based on this principle.
[0037] In some embodiments, the ignition circuit includes a second transformer T2. The primary winding of the second transformer T2 is used to receive the oscillation signal output by the self-excited oscillation circuit. The two ends of the secondary winding of the second transformer T2 are a high-voltage output terminal and a high-voltage return terminal, respectively. The high-voltage output terminal is located in the combustion area. The secondary winding of the second transformer generates high-voltage electricity according to the oscillation signal and outputs it through the high-voltage output terminal.
[0038] In some embodiments, one end (end 2) of the secondary winding of the first transformer T1 is connected to the primary winding (end 1) of the second transformer, and the other end (end 4) of the secondary winding of the first transformer T1 is grounded. One of the input terminals of the flame detection circuit is connected between the secondary winding of the first transformer T1 and the primary winding of the second transformer T2, and the other input terminal of the flame detection circuit is connected to the high voltage return terminal.
[0039] During ignition, the ignition control signal FIRE is low, and the second switch is turned on. The sixth resistor R6 is short-circuited, resulting in faster and higher charging and discharging of the sixth capacitor C6. The voltage at the two terminals of the secondary winding of the first transformer T1 reaches a maximum of over 200V, charging the eighth capacitor C8. The charging voltage is high enough to turn on the fourth diode D4 (D4's characteristic is 200V conduction), causing the eighth capacitor C8 to discharge, turning on the second transformer T2, and initiating ignition.
[0040] The ignition principle is that the secondary winding of the second transformer T2 outputs a high-voltage arc with a voltage as high as 20,000V, and the electric spark ignites the gas to complete the ignition. The secondary winding of the second transformer T2 is not connected to any circuit or voltage level; it is isolated and can discharge from end to end, or discharge to any conductor near it.
[0041] In this embodiment, the high-voltage output terminal (terminal 3) of the secondary winding of the second transformer T2 discharges to the fire bar or the casing, and the high-voltage return terminal (terminal 4) also has a high-voltage output. However, this high voltage is grounded through the discharge tube and then forms a loop with terminal 3 through the grounding circuit.
[0042] In this embodiment, the high-voltage output terminal of the secondary winding of the second transformer T2 is located in the fire scene. By connecting the input terminal of the flame detection circuit to the output circuit of the ignition circuit, when there is a flame, the output circuit of the ignition circuit forms a diode effect, which lowers the input voltage of the flame detection circuit. This achieves the goal of only needing to lead out one ignition wire from the board, without setting up a flame probe, and thus without needing to connect the two wires.
[0043] In some embodiments, the second switching circuit includes a PNP transistor P1, the base of which is used to receive the ignition control signal FIRE, the emitter of which is connected to the DC power supply VCC, and the collector of which is connected to terminal 10 of the second primary winding of the first transformer T1.
[0044] When not igniting, the ignition control signal FIRE is high, P1 is not conducting, and the DC power supply VCC is supplied to the second primary winding of the first transformer T1 through the sixth resistor R6. When ignition occurs, the ignition control signal FIRE is low, and P1 is conducting.
[0045] In some embodiments, the first switch includes an NPN transistor N1, the base of which is connected to terminal 6 of the second primary winding of the first transformer T1, the collector of which is connected to terminal 9 of the first primary winding of the first transformer T1, and the emitter of which is connected to ground.
[0046] The on / off state of NPN transistor N1 is controlled by the output resonant signal of a low-frequency resonant circuit composed of R15 and C6.
[0047] In some embodiments, a discharge tube D3 is connected between the input terminal of the flame detection circuit and the high-voltage return terminal, with the other end of the discharge tube D3 connected to ground. The high-voltage output terminal (terminal 3) of the second transformer T2 discharges to the burner or the casing, and the high-voltage return terminal (terminal 4) also has a high-voltage output. However, this high voltage is grounded through the discharge tube D3 and then forms a loop with the high-voltage output terminal through the grounding circuit.
[0048] In some embodiments, the flame detection circuit includes a clamping circuit, a filtering circuit, and an isolation circuit.
[0049] The clamping circuit is connected to the input terminal of the flame detection circuit, the filter circuit is connected to the clamping circuit, and the isolation circuit is connected between the output terminals of the filter circuit and the flame detection circuit.
[0050] In some embodiments, the isolation circuit includes an NMOS transistor N2, the gate of which is connected to the output of the filter circuit, the source of which is connected to ground, the drain of which is connected to a DC power supply, and the output of the flame detection circuit is connected to the drain of N2.
[0051] The clamping circuit includes a first diode D1, one end of which is connected to the DC power supply VCC, and the other end is connected to the input terminal of the flame detection circuit, which is used to limit the voltage input to the flame detection circuit within the normal range.
[0052] The filter circuit includes the fifth capacitor C5 and the twelfth resistor R12, which serve as isolation and filtering.
[0053] The input of the flame detection circuit is also connected to the DC power supply VCC via a pull-up resistor R7. When there is no flame, N2 is turned on through the weak pull-up resistor R7, and the flame detection FLAME CHEK1 detects a low level. When there is a flame, the sine wave output from the secondary winding of the first transformer T1 is pulled down, which can better turn off N2. The FLAME CHEK1 detects a high level. In this design, the NMOS transistor N2 is used for isolation, making the entire circuit safer.
[0054] Example 2: This example proposes a gas water heater, including a control module capable of generating and sending an ignition control signal FIRE, and the ignition and flame detection circuit described in Example 1. The ignition and flame detection circuit includes a self-excited oscillation circuit, an ignition circuit, and a flame detection circuit. The self-excited oscillation circuit receives the ignition control signal FIRE and oscillates to generate an oscillation signal. The ignition circuit includes an input circuit and an output circuit. The input circuit receives the oscillation signal, and the output circuit generates and releases high-voltage electricity based on the oscillation signal to ignite the gas. One input terminal of the flame detection circuit is connected to the output terminal of the self-excited oscillation circuit, and the other is connected to the output circuit of the ignition circuit. The flame detection circuit generates and outputs a flame detection signal. The flame detection circuit sends the detected flame detection signal to the control module.
[0055] Other structures of the ignition and flame detection circuit can be found in Embodiment 1, and will not be repeated here.
[0056] In this embodiment of the gas water heater, the flame detection and ignition functions do not interfere with each other, and the flame detection in this solution does not require a flame probe, resulting in less wiring and reduced hardware costs.
[0057] Of course, the above description is not intended to limit the present utility model, and the present utility model is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present utility model should also fall within the protection scope of the present utility model.
Claims
1. An ignition and flame detection circuit, characterized by, The ignition and flame detection circuit comprises: a self-oscillation circuit for receiving an ignition control signal and generating an oscillation signal; an ignition circuit, the input circuit of the ignition circuit receiving the oscillation signal, and the output circuit of the ignition circuit being used to release high-voltage electric sparks to ignite gas; a flame detection circuit, one of the input terminals of the flame detection circuit being connected to the output terminal of the self-oscillation circuit, and the other input terminal of the flame detection circuit being connected to the output circuit of the ignition circuit, the flame detection circuit generating a flame detection signal and outputting the flame detection signal.
2. The ignition and flame detection circuit of claim 1, wherein, The self-oscillation circuit comprises a first transformer, one end of a first primary winding of the first transformer being connected to a DC power supply, the other end of the first primary winding being connected to ground through a first switch, one end of a second primary winding of the first transformer being connected to the DC power supply through a first path, the other end of the second primary winding being connected to the control terminal of the first switch, and the secondary winding of the first transformer being used to output the oscillation signal. The control terminal of the second switch is used to receive the ignition control signal.
3. The ignition and flame detection circuit of claim 2, wherein, The first switch comprises an NPN transistor, the base of the NPN transistor being connected to the second primary winding of the first transformer, the collector of the NPN transistor being connected to the first primary winding of the first transformer, and the emitter of the NPN transistor being connected to ground.
4. The ignition and flame detection circuit of claim 2, wherein, The second switch circuit comprises a PNP transistor, the base of the PNP transistor being used to receive the ignition control signal, the emitter of the PNP transistor being connected to the DC power supply, and the collector of the PNP transistor being connected to the second primary winding of the first transformer.
5. The ignition and flame detection circuit of claim 2, wherein, The ignition circuit comprises a second transformer, the primary winding of the second transformer being used to receive the oscillation signal, and the secondary winding of the second transformer having two ends, which are respectively a high-voltage output terminal and a high-voltage return terminal, the high-voltage output terminal being arranged in a combustion area, and the secondary winding of the second transformer generating high-voltage electric sparks according to the oscillation signal and outputting the high-voltage electric sparks through the high-voltage output terminal.
6. The ignition and flame detection circuit of claim 5, wherein, One of the input terminals of the flame detection circuit is connected between the secondary winding of the first transformer and the primary winding of the second transformer, and the other input terminal of the flame detection circuit is connected to the high-voltage return terminal.
7. The ignition and flame detection circuit of claim 6, wherein, A discharge tube is further connected between the input terminal of the flame detection circuit and the high-voltage return terminal, and the other end of the discharge tube is connected to ground.
8. The ignition and flame detection circuit of claim 2, wherein, A sixth resistor is connected between the first path of one end of the second primary winding of the first transformer and the DC power supply.
9. The ignition and flame detection circuit according to any one of claims 1-8, characterized in that, The flame detection circuit comprises: a clamping circuit connected to the input terminal of the flame detection circuit; a filter circuit connected to the clamping circuit; an isolation circuit connected between the filter circuit and the output terminal of the flame detection circuit.
10. A gas water heater comprising a control module capable of generating and transmitting a firing control signal, characterized in that, The ignition and flame detection circuit further comprises the ignition and flame detection circuit according to any one of claims 1-9.