All-digital ignition device suitable for large-flow combustion simulator

Abstract

The all-digital ignition device comprises a fuel valve control circuit, a single-chip microcomputer, a high-voltage ignition circuit and a spark plug which are sequentially connected, and a flame detection circuit is further arranged between the single-chip microcomputer and the spark plug. The high-voltage ignition circuit is used for generating high-voltage ignition pulses with adjustable frequency and pulse width on an ignition needle; the flame detection circuit is used for detecting whether flames exist on the probe; the fuel valve control circuit is used for synchronously controlling a fuel valve, the fuel valve control circuit, the high-voltage ignition circuit and the flame detection circuit are controlled through a single-chip microcomputer, ignition pulses with the adjustable frequency and duty ratio can be stably provided, a universal spark plug is adopted as an ignition probe, flames are detected through the unilateral conductivity of flame ions, and the flame detection precision is improved. Meanwhile, ignition and flame detection adopt an integrated probe design, so that the installation and maintenance cost is reduced; and a communication interface is provided, so that the intelligent and internet-of-things functions are realized.

Description

Technical Field

[0001] The invention relates to the technical field of burner simulation, and in particular to a full-digital ignition device suitable for a large-flow combustion simulator. Background Art

[0002] The ignition device can be used to replace the combustion simulator of the engine. It can provide air-fuel ratio mixture simulation, adjustable combustion temperature and large air volume output. It is mainly used for aging tests such as three-way catalytic devices. In the combustion simulator, the ignition device needs to accurately judge the ignition timing and the ignition state after ignition. The test system should control the air intake and fuel valve according to the ignition and flame conditions to avoid repeated ignition or fuel leakage.

[0003] Existing ignition devices are all ordinary analog circuits for stoves, water heaters, small boilers and other occasions. Once the circuit is made, the pulse frequency and duty cycle are fixed and cannot be flexibly adjusted according to different occasions; flame detection is mostly based on the thermocouple principle, and the reaction speed is slow; some products that use the flame resistance characteristics to detect flames also have low flame detection sensitivity, do not consider the resistance change caused by the moisture content in the mixed gas, and the application occasions are fixed; the ignition needle and the flame detection needle are independent, and the replacement of the ignition needle or the flame detection needle requires on-site adjustment of the gap, which is more complicated to install. These shortcomings will cause the fuel valve to malfunction during operation, and increase the equipment maintenance cost. The ignition device is the core component of the combustion simulator, and its working reliability directly affects the overall performance of the combustion simulator, but the existing ignition devices cannot meet the requirements. In addition, the traditional analog ignition device has no communication interface and cannot be IoT-based and intelligent, which limits the application scenarios of the ignition device.

[0004] Therefore, it is very necessary to research and develop a fully digital special ignition device that meets the needs of large-flow combustion simulators, which can be used in many occasions, is easy to install and maintain, is economical, and is fully digital and intelligent. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a fully digital ignition device suitable for a large-flow combustion simulator, which can stably provide ignition pulses with adjustable frequency and duty cycle, adopt a universal spark plug as an ignition probe, and use the unidirectional conductivity of flame ions to detect the flame, with high reliability. At the same time, the ignition and flame detection adopt an integrated probe design to reduce installation and maintenance costs; it has a communication interface and has intelligent and Internet of Things functions.

[0006] To achieve the above object, the present invention provides the following technical solutions: A fully digital ignition device suitable for a large-flow combustion simulator comprises a fuel valve control circuit, a single-chip microcomputer, a high-voltage ignition circuit and a spark plug connected in sequence, wherein a flame detection circuit is also arranged between the single-chip microcomputer and the spark plug; the high-voltage ignition circuit is used to generate a high-voltage ignition pulse with an adjustable frequency and pulse width on an ignition needle; the flame detection circuit is used to detect whether a flame exists on the detection needle; the fuel valve control circuit is used to synchronously control the fuel valve, and the fuel valve control circuit, the high-voltage ignition circuit and the flame detection circuit are controlled by the single-chip microcomputer.

[0007] As a further solution of the present invention, the working process of the high-voltage ignition circuit is as follows: after the single-chip microcomputer generates a PWM waveform, it drives the power transformer to work through the push-pull amplifier circuit, and obtains an AC voltage at the secondary side of the power transformer. The AC voltage charges the energy storage capacitor through the rectifier diode, and the AC voltage is detected by a voltage regulator diode. Once the voltage amplitude is greater than the diode breakdown voltage, the diode breakdown triggers the high-voltage thyristor to turn on. At this time, the voltage on the energy storage capacitor will be directly applied to the primary coil of the high-voltage package through the high-voltage thyristor, and the secondary coil of the high-voltage package will immediately induce a high voltage of 15kV~20kV, and this high-voltage signal will be discharged through the spark plug probe.

[0008] As a further solution of the present invention, the working process of the flame detection circuit is as follows: a PWM wave for detection is generated by a single-chip microcomputer, and a transformer is driven by a push-pull amplifier circuit. An AC voltage signal with adjustable frequency and pulse width is generated at the secondary end of the transformer and applied to the detection probe as a detection voltage. By utilizing the unidirectional conductivity of flame ions, if a flame exists, the AC voltage signal will be rectified. At this time, a negative voltage is obtained at one end of the flame. After filtering, the negative voltage is sent to a comparator for voltage comparison. The output level of the comparator is detected by the single-chip microcomputer. When the comparator output is a low level, it indicates that a flame exists, and the single-chip microcomputer determines that the ignition is successful.

[0009] As a further scheme of the present invention, the working process of the fuel valve control circuit is as follows: the single chip microcomputer automatically controls the fuel valve through ignition and flame detection to avoid leakage of the fuel valve; the single chip microcomputer opens the air intake fan for pre-purge, then sends an ignition pulse, and then opens the fuel valve. The fuel will be immediately ignited after passing through the fuel valve and mixing with the intake air. At this time, the single chip microcomputer detects whether the ignition is successful through the flame detection circuit. If successful, it enters the real-time flame detection state. If the ignition fails or the flame is accidentally extinguished, the fuel valve is immediately closed and an alarm signal is sent to avoid fuel leakage.

[0010] As a further solution of the present invention, the high-voltage pulse ignition circuit includes a transformer and an energy storage capacitor; a PWM wave is generated by a single-chip microcomputer, which drives the transformer to work after amplification, and a high voltage is sensed at the output end of the transformer. The energy storage capacitor is charged after rectification, and the energy storage capacitor is used to drive the high-voltage package to generate an ignition pulse.

[0011] As a further aspect of the present invention, the spark plug serves as a discharge and flame detection probe.

[0012] As a further solution of the present invention, the flame detection circuit includes a transformer, a detection power rectifier, and a comparator; a PWM waveform is generated by a single-chip microcomputer to drive the transformer, and an AC power supply with adjustable frequency and pulse width is generated at the secondary of the transformer. The AC power supply reaches the detection probe for detecting whether a flame exists.

[0013] The present invention has the following beneficial effects: In the present invention, the high-voltage ignition circuit adopts an adjustable ignition pulse frequency and duty cycle, which is flexible to use and solves the problem of use in multiple occasions, especially the adaptation of large-flow combustion simulators; the flame detection circuit adopted combines the detection probe and the ignition probe, and utilizes the ion unidirectional conductivity characteristics of the flame to accurately detect the flame, and adopts the spark plug as the ignition and detection probe, which solves the flame detection reliability problem and reduces the on-site installation and debugging costs; the fuel valve control circuit adopted is based on the single-chip microcomputer as the core, and integrates the full automation of ignition control, flame detection control, and fuel valve control, which solves the shortcomings of the ignition controller with analog devices as the core, which has a single function and a fixed application occasion; for bench applications, it solves the shortcomings of no multi-channel control, no communication interface, and no Internet of Things and intelligence.

[0014] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a module schematic diagram of a fully digital ignition device suitable for a large flow combustion simulator mentioned in the present invention.

[0016] Figure 2 It is a schematic diagram of the application of the present invention on a large flow combustion simulator.

[0017] Figure 3 It is a schematic diagram of the high-voltage ignition circuit, flame detection circuit and fuel valve control circuit mentioned in the present invention.

[0018] Figure 4 It is the operation logic diagram of the single chip microcomputer when the present invention is applied on the combustion simulator. DETAILED DESCRIPTION

[0019] The present invention will be further explained below in conjunction with the accompanying drawings and related knowledge, and described clearly and completely. Obviously, the described application is only a part of the embodiments of the present invention, rather than all the embodiments.

[0020] Reference Figure 1-Figure 4 As shown, the present invention provides a fully digital ignition device suitable for a large flow combustion simulator, comprising a fuel valve control circuit, a single chip microcomputer, a high voltage ignition circuit and a spark plug connected in sequence, and a flame detection circuit is also arranged between the single chip microcomputer and the spark plug; the high voltage ignition circuit is used to generate a high voltage ignition pulse with adjustable frequency and pulse width on the ignition needle; the flame detection circuit is used to detect whether a flame exists on the detection needle; the fuel valve control circuit is used to synchronously control the fuel valve, and the fuel valve control circuit, the high voltage ignition circuit and the flame detection circuit are controlled by the single chip microcomputer; the fully digital ignition device of the present invention has good stability and reliability, and can operate stably for a long time in an industrial environment.

[0021] In the present invention, reference is made to Figure 2 As shown, a fully digital single-chip microcomputer design is adopted, and the high-voltage pulse ignition circuit includes: transformer drive, high-voltage rectification, energy storage capacitor charging, and energy storage capacitor discharge. The transformer is driven to charge the energy storage capacitor by using a PWM wave; the PWM wave is generated by the single-chip microcomputer, and after amplification, the transformer is driven to work, and the high voltage is induced at the output end of the transformer, and the energy storage capacitor is charged after rectification; the energy storage capacitor is further used to drive the high-voltage package to generate an ignition pulse; the energy storage capacitor will discharge once in each PWM wave cycle, and its discharge threshold depends on the breakdown voltage of the voltage-stabilizing diode; during discharge, a high voltage is applied to the primary coil of the high-voltage package through a high-voltage thyristor, and the secondary coil of the high-voltage package synchronously generates a high-voltage ignition pulse. Furthermore, since the ignition pulse is generated by a PWM wave, the ignition pulse frequency, waveform, and duty cycle can be adjusted. The adjustable ignition pulse frequency and duty cycle are used flexibly, which solves the adaptation of multiple occasions, especially the large-flow combustion simulator, and realizes more accurate control of the ignition process, real-time monitoring of the flame state, timely feedback and adjustment, and improves the safety and efficiency of combustion, while reducing the cost and complexity of the equipment.

[0022] That is to say, under the fully digital single-chip design framework, the high-voltage pulse ignition circuit shows excellent performance and flexibility. In the transformer drive link, the PWM wave generated by the single-chip microcomputer is amplified and applied to the transformer. This process is like injecting a precise power source into the entire ignition system. Based on the principle of electromagnetic induction, the transformer cleverly senses high voltage at its output end. This high voltage is then carefully processed by the rectifier to convert unstable AC into DC, creating ideal conditions for charging the energy storage capacitor.

[0023] The energy storage capacitor acts as the energy "reservoir" of the entire circuit, and performs regular charge and discharge cycles in each PWM wave cycle. Its charging process relies on the rectified high voltage, while the discharge is achieved through the key component of the high-voltage thyristor. The breakdown voltage of the Zener diode is like a precise "valve threshold" that determines when the energy storage capacitor starts the discharge mode. When this threshold is reached, the energy storage capacitor quickly releases energy and applies high voltage to the primary coil of the high-voltage package through the high-voltage thyristor. The high-voltage package, with its unique voltage transformation characteristics, synchronously generates high-voltage ignition pulses in the secondary coil that are sufficient to ignite the fuel.

[0024] Since the ignition pulse is closely connected with the PWM wave, the frequency, waveform and duty cycle of the ignition pulse can be flexibly adjusted. In the application scenario of the large-flow combustion simulator, this adjustability shows unparalleled advantages. For example, at the beginning of the combustion simulator, the frequency and duty cycle of the ignition pulse can be appropriately increased to quickly establish a stable combustion state. As the combustion process progresses and stabilizes, the frequency and duty cycle can be reduced accordingly to achieve the dual goals of energy saving and precise fire control. Different fuel types, combustion environments and flow requirements can be perfectly adapted through flexible adjustment of the ignition pulse parameters. Whether facing a special fuel mixture with high concentration and large flow, or under complex and changeable combustion simulation conditions, the ignition device can rely on its precise parameter adjustment capabilities to ensure the efficiency, stability and safety of the combustion process, providing a solid guarantee for the reliable operation of the large-flow combustion simulator.

[0025] In the present invention, reference is made to Figure 2 As shown, the flame detection circuit includes: transformer drive, detection power rectification, comparator detection, and flame detection by utilizing the unidirectional conductivity of flame ions; the positive and negative ion characteristics generated by flame combustion make it equivalent to a diode, and the AC detection power supply utilizes the unidirectional conductivity of the flame, and its positive half cycle flows into the public ground through the flame, and its negative half cycle is blocked, thereby achieving a rectification effect. The realization of this rectification effect generates a negative DC voltage at one end of the flame, which is converted by the detection circuit composed of a voltage comparator for detection by the single-chip microcomputer.

[0026] Furthermore, in the flame detection circuit, the transformer driver plays a key role in power supply. It converts and adapts the input electrical energy to provide appropriate voltage conditions for subsequent detection links.

[0027] The comparator detection link is the core judgment unit of the entire flame detection circuit. The DC signal after flame rectification is input into the comparator, which compares it with the preset reference voltage. If the flame exists and the rectification effect is obvious, the signal level of the comparator output will change accordingly, and this changed signal is transmitted to the single-chip microcomputer. With its powerful processing capability, the single-chip microcomputer can quickly and accurately identify the changes in the comparator output signal and then judge the state of the flame. For example, when the single-chip microcomputer detects that the signal output by the comparator meets the characteristics of the existence of the flame, it can trigger the corresponding control action in the system, such as maintaining the normal operation of the combustion equipment, adjusting the fuel supply or ventilation volume, etc.; and when the flame is detected to be extinguished or abnormal, the single-chip microcomputer can promptly start the alarm mechanism or execute the safety processing procedure after the flame is extinguished to ensure the safety and reliability of the entire combustion system. It provides an efficient, accurate and stable flame monitoring method for large-flow combustion simulators and various combustion equipment, effectively avoiding safety accidents and unstable operation problems that may be caused by the failure to detect flame failures in time.

[0028] In the present invention, the fuel valve control circuit performs logical processing of pulse ignition and flame detection in a single-chip microcomputer; a single-chip microcomputer is used to realize full automation of ignition control, flame detection, and fuel valve control; single-chip microcomputer control can realize full automation of ignition, detection, and fuel valve control. In addition, the single-chip microcomputer has various communication interfaces, which can realize intelligent equipment and Internet of Things.

[0029] Furthermore, in the flame detection link, the MCU continuously receives information about the DC signal after flame rectification from the comparator. Once it detects that the flame is extinguished or the combustion is abnormal, such as the flame ion current is lower than the set threshold, the MCU responds quickly. Based on these comprehensive logical judgment results, the MCU precisely controls the fuel valve control circuit. In the early stage of ignition, if the flame is not successfully established, the MCU will control the fuel valve to remain closed or only allow a very small flow of fuel to pass through to prevent fuel accumulation from causing danger. When the flame is burning stably, the MCU accurately adjusts the opening of the fuel valve according to the combustion requirements to achieve a perfect match between the fuel supply and the combustion conditions, ensuring the maximization of combustion efficiency and stability.

[0030] In the present invention, a spark plug is used as a discharge and flame detection probe; the use of a universal spark plug as a probe is more economical than a special probe, and is easy to install and replace; and the same probe is used for ignition discharge and flame detection; the pulse discharge and flame detection probes are designed together, and a single-chip microcomputer is used to control the pulse discharge and flame detection circuits, which can avoid the conflict between the discharge and detection functions, and the ignition discharge and flame detection functions are integrated on the same universal spark plug probe, and are accurately controlled by the single-chip microcomputer, effectively avoiding the problem of conflict between the discharge and detection functions. The single-chip microcomputer can accurately coordinate the time sequence and signal processing of pulse discharge and flame detection with its powerful computing and logic processing capabilities. In the pulse discharge stage, the single-chip microcomputer controls the relevant circuits to make the spark plug generate high-voltage discharge to ignite the fuel, and in the discharge gap or at a specific moment, the circuit is quickly switched to the flame detection mode, and the unidirectional conductivity of the flame ions is used to obtain the flame state information through the detection circuit and transmit it back to the single-chip microcomputer for analysis and judgment. Through reasonable timing control and signal isolation processing, it is ensured that the two functions do not interfere with each other and work together on the same probe, further improving the integration and reliability of the entire combustion system, simplifying the system's hardware structure and wiring complexity, and providing strong technical support for the miniaturization and intelligent development of combustion equipment.

[0031] The fully digital ignition device of the present invention can be used in many occasions; it has digital communication function, high-voltage ignition pulse output with adjustable pulse width and frequency, an integrated ignition and detection probe, and a flame detection power supply with adjustable pulse width and frequency; based on these advantages, the fully digital ignition device suitable for large-flow combustion simulators can be used in various special occasions such as test benches, large boilers, laboratories, etc., and can be put into use immediately after simply setting the scene parameters according to the application scenario.

[0032] The following provides specific embodiments of the present invention. Example 1

[0033] A fully digital ignition device suitable for a large flow combustion simulator, comprising: The high-voltage ignition circuit is used to generate a high-voltage ignition pulse with adjustable frequency and pulse width on the ignition needle.

[0034] The flame detection circuit is used to detect whether a flame exists on the detection needle.

[0035] The fuel valve control circuit is used for synchronously controlling the fuel valve.

[0036] Further preferred, the high-voltage ignition circuit is a fully digital structure, using a single-chip microcomputer to generate a PWM waveform and then drive the power transformer to work through a push-pull amplifier circuit, obtaining an AC voltage with an amplitude of about 200V at the secondary of the power transformer, which charges the energy storage capacitor through a rectifier diode. At the same time, the AC voltage is detected by a voltage-stabilizing diode. Once the voltage amplitude is greater than the diode breakdown voltage, the diode breakdown triggers the high-voltage thyristor to turn on. At this time, the voltage on the energy storage capacitor will be directly applied to the primary coil of the high-voltage package through the high-voltage thyristor, and the secondary coil of the high-voltage package will immediately induce a high voltage of about 15kV~20kV, and this high-voltage signal will be discharged through the spark plug probe. Since the PWM pulse frequency duty cycle of the single-chip microcomputer can be adjusted arbitrarily, the frequency and pulse width of the high-voltage pulse can also be adjusted, achieving the purpose of digital regulation.

[0037] Thus, in the whole combustion system, the high-voltage ignition circuit adopts a fully digital structure design with many outstanding advantages. This structure uses a single-chip microcomputer as the core control unit, which can realize accurate digital control of the ignition process. The PWM (pulse width modulation) waveform is generated by the single-chip microcomputer, which lays a precise foundation for the subsequent voltage conversion and energy transfer. The PWM waveform generated by the single-chip microcomputer is first amplified by the push-pull amplifier circuit. With its unique circuit structure, the push-pull amplifier circuit can effectively enhance the driving ability of the PWM waveform, so that it is sufficient to drive the relatively large power transformer to work normally. When the amplified PWM waveform acts on the power transformer, according to the principle of electromagnetic induction, an AC voltage with an amplitude of about 200V can be obtained at the secondary of the power transformer. The obtained 200V AC voltage then enters the rectification link, and the rectifier diode plays a key role. The rectifier diode can convert the AC voltage into a DC voltage, thereby charging the energy storage capacitor. The energy storage capacitor plays an important role as an "energy storage pool" in the whole ignition circuit. It continuously accumulates the electric energy obtained from the rectifier diode to make full energy preparation for the subsequent generation of high-voltage pulses. At the same time, the 200V AC voltage is closely "monitored" by a voltage regulator diode. Once the amplitude of this AC voltage is greater than the breakdown voltage of the voltage regulator diode, the voltage regulator diode will immediately break down. This breakdown is not a fault, but a clever triggering mechanism, which will cause the high-voltage thyristor to conduct. When the high-voltage thyristor is turned on, the voltage stored on the energy storage capacitor will be directly applied to the primary coil of the high-voltage package through the high-voltage thyristor. Since the high-voltage package has the characteristics of voltage transformation, according to the law of electromagnetic induction, a high voltage of about 15kV~20kV will be immediately induced in its secondary coil. This high-voltage signal is then discharged through the spark plug probe, thereby generating a strong electric spark between the spark plug electrodes, which is enough to ignite the fuel in the combustion chamber and realize the ignition function. Since the entire process is driven based on the PWM waveform generated by the single-chip microcomputer, the PWM pulse frequency and duty cycle of the single-chip microcomputer can be arbitrarily adjusted according to actual needs. This means that the frequency and pulse width of the high-voltage pulse can also be flexibly adjusted, thereby achieving the purpose of digital adjustment of the high-voltage ignition circuit. This digital adjustment capability has great advantages in different combustion application scenarios. For example, in a large-flow combustion simulator, the frequency and pulse width of the high-voltage pulse can be adjusted in time according to the different simulated combustion conditions and fuel characteristics to achieve the best ignition effect and combustion stability. For different types of fuels, such as gasoline, diesel, natural gas, etc., the high-voltage pulse parameters can also be adjusted to adapt to their respective ignition requirements, improve combustion efficiency, and reduce pollutant emissions. At the same time, it can also be dynamically adjusted according to the operating status of the combustion equipment to ensure the safe, stable and efficient operation of the entire combustion system.

[0038] The flame detection circuit uses the unidirectional conductivity principle of flame ions to detect whether the ignition is successful. The structure can be simplified by integrating the detection and ignition probes during design. The detection principle is that the microcontroller generates a PWM wave for detection, drives the transformer through a push-pull amplifier circuit, and generates an AC voltage signal with adjustable frequency and pulse width at the secondary end of the transformer. This voltage signal is applied to the detection probe as a detection voltage. Using the unidirectional conductivity of flame ions, if there is a flame, the AC voltage signal will be rectified. At this time, a negative voltage will be obtained at one end of the flame. After filtering, the negative voltage is sent to the comparator for voltage comparison. The comparator output level is detected by the microcontroller. When the comparator output is low, it means that the flame exists, and the microcontroller determines that the ignition is successful.

[0039] Thus, the flame detection circuit can accurately detect whether the ignition is successful based on the unique physical principle of unidirectional conductivity of flame ions. During the combustion process, the flame will ionize the surrounding gas to produce flame ions. These ions have unidirectional conductivity, which becomes the key basis for detecting whether the flame exists or not. In terms of design, the integration of detection and ignition probes is an ingenious and practical idea, which brings significant advantages in structural simplification. Traditional designs may require the separate setting of independent ignition probes and detection probes, which not only increases the complexity of the system, but also may involve more wiring and space occupation. The integrated design makes the entire ignition and detection system more compact, reduces the number of parts, reduces the probability of failure, and is also easy to install and maintain. In actual application scenarios, it can improve the overall reliability and operability of the equipment. The microcontroller plays a core control role in the flame detection process, generating a PWM wave specifically for detection. This PWM wave is like a precise signal source, providing the initial drive signal for the subsequent detection process. Subsequently, the PWM wave is amplified by a push-pull amplifier circuit. With its own circuit characteristics, the push-pull amplifier circuit can effectively enhance the driving ability of the PWM wave, making it sufficient to drive the transformer to work normally. The negative voltage signal after filtering will be sent to the comparator for voltage comparison. The received negative voltage signal is compared with a preset reference voltage. When there is a flame, the negative voltage signal after rectification and filtering will cause the comparator output level to change. In this design, when the comparator output is low, it means that there is a flame. The microcontroller can accurately determine whether the ignition is successful by detecting the output level of the comparator. This judgment logic based on the comparator output level is simple and effective, and can quickly and accurately feedback the existence status of the flame in the combustion system, so that the entire system can make corresponding adjustments in time according to whether the ignition is successful, such as maintaining normal combustion state, adjusting the fuel supply, or taking other necessary control measures to ensure the safety, stability and efficiency of the combustion process.

[0040] The fuel valve control circuit is a single chip microcomputer that automatically controls the fuel valve through ignition and flame detection to prevent leakage of the fuel valve. The principle is that the single chip microcomputer turns on the air intake fan for pre-purge, then sends an ignition pulse, and then opens the fuel valve. After the fuel passes through the fuel valve and mixes with the intake air, it will be immediately ignited. At this time, the single chip microcomputer detects whether the ignition is successful through the flame detection circuit. If successful, it enters the real-time flame detection state. If the ignition fails or the flame is accidentally turned off, the fuel valve is immediately closed and an alarm signal is issued to prevent fuel leakage. Example 2

[0041] Reference Figure 2 As shown, a fully digital ignition device suitable for a large-flow combustion simulator includes an automatically controlled fuel valve and an air inlet valve; the combustion simulator system includes an air intake fan 1, an air inlet pipe 2, a fuel inlet pipe 3, a fuel valve 4, a mixing chamber 5, a spark plug 6, a combustion chamber 7 and a fully digital ignition control device of the present invention; when the system starts working, the ignition control device turns on the air intake fan, starts ignition, opens the fuel valve, waits for the ignition to be completed, and then automatically detects the flame to determine whether the ignition is successful. If the ignition fails, the fuel valve is closed in time and an alarm signal is issued.

[0042] Reference Figure 3As shown in the figure, the high-voltage ignition circuit uses an STM32 microcontroller as a control element, and sends an ignition signal through its PWM1 port. The signal is a PWM signal with adjustable pulse width and frequency. The PWM signal passes through a push-pull amplifier composed of Q1, Q2, and Q3 to start the power transformer T1. The primary coil of the transformer T1 is maintained by the PWM signal continuously output by the STM32 microcontroller to maintain oscillation. The oscillation frequency is arbitrarily adjusted by the STM32 microcontroller receiving communication instructions from the host computer. When oscillation occurs, a high-voltage AC signal of about 200V is generated at the secondary of the power transformer T1. The high-voltage AC The signal is rectified by diode D1 and charged to energy storage capacitor C1. Since capacitor C1 has no discharge circuit, the high-voltage signal is applied to high-voltage thyristor D4. At the same time, oscillation transformer T1 also provides high voltage to voltage zener diode D2. When the voltage reaches the breakdown voltage of voltage zener diode D2, voltage zener tube D2 breaks down and conducts, diode D3 conducts, triggering high-voltage thyristor D4 to conduct, thereby applying a high voltage to the primary of high-voltage package T2. The secondary of high-voltage package T2 will induce a 15kV~20kV ignition high voltage, connect the spark plug to the secondary of high-voltage package T1, and generate discharge electric sparks through the spark plug. The frequency of discharge can adjust the PWM output frequency of STM32 microcontroller. The high-voltage ignition circuit is precisely controlled by the STM32 microcontroller, combined with the coordinated work of a series of components such as push-pull amplifiers, power transformers, rectifier diodes, energy storage capacitors, voltage-stabilizing diodes, thyristors and high-voltage packages, to achieve the generation of ignition high voltage and adjustable discharge frequency. It can adapt well to different combustion conditions and provide a strong guarantee for the reliable operation of combustion equipment.

[0043] The flame detection device has a working principle of using the STM32 microcontroller to output a PWM signal at the PWM2 port, and the push-pull amplifier composed of Q4, Q5, and Q6 drives the transformer T3 to work. The secondary end of the T3 transformer will generate an AC voltage for detection, and the AC voltage reaches the spark plug discharge probe through the capacitor C3. Since the flame during fuel combustion will produce positive and negative ions, the flame can actually be equivalent to a diode and also has the unidirectional conductivity of the diode. Using this characteristic, after the ignition pulse is completed, if the ignition is successful and a flame is generated, the AC voltage will pass through the flame equivalent diode. The flame equivalent diode is turned on during the positive half cycle of the AC voltage and is turned off during the negative half cycle. At this time, a DC negative voltage will be generated on the discharge probe, and the voltage will charge the capacitor C2 through the resistor R1. The diodes D5 and D6 are clamping diodes, which are used to protect the input end of the voltage comparator U1 from exceeding the conduction voltage of the clamping diode. The DC negative voltage passes through the U1 comparator and outputs a low level for detection by the STM32 microcontroller. The flame detection method combines the high-voltage ignition device and the flame detection device, integrates the flame detection probe and the ignition probe, adopts physical principles and simple circuits to realize flame detection design, simplifies circuit design, reduces product cost and on-site installation cost, and reduces product manufacturing cost, including component procurement cost, circuit board production cost, etc. At the same time, it also reduces on-site installation cost, because the installation process is simpler and faster, reduces labor hours and possible installation errors, can effectively reduce costs and simplify the installation process while ensuring the accuracy of flame detection, and provides reliable flame detection guarantee for the stable operation of related combustion equipment.

[0044] The fuel valve control circuit is controlled by the STM32 microcontroller, which automatically controls the switch of the fuel valve according to the ignition and flame conditions to avoid fuel leakage or flameout. The STM32 microcontroller IO port controls the transistor Q5 and relay K1, and controls the energization of the fuel valve K2 coil through the normally open contact of K1.

[0045] like Figure 4 As shown in the figure, when applied on the combustion simulator, the single chip microcomputer controls the high-voltage ignition through logical judgment, and the flame detection and fuel valve realize full automation; the specific working process is to turn on the air intake fan to start pre-purge, start the ignition pulse after 1 second, and open the fuel valve after a delay of 0.1 second. The ignition pulse lasts for 2 seconds (settable) and then turns off the ignition pulse to start flame detection. If the flame detection is abnormal, the ignition pulse is turned on again and the ignition is re-ignited (the number of repetitions can be set); if the flame detection is still abnormal, the STM32 single chip microcomputer immediately closes the fuel valve and sends out an alarm signal; if the flame detection is normal, it is judged that the ignition is successful. At this time, the STM32 single chip microcomputer starts to detect the flame status in real time. Once a flameout accident occurs during the working process, the STM single chip microcomputer will immediately close the fuel valve and send out an alarm signal.

[0046] The technical principle of the present invention is described above in combination with the specific embodiments, which are only preferred implementations of the present invention. The protection scope of the present invention is not limited to the above embodiments, and all technical solutions under the idea of ​​the present invention belong to the protection scope of the present invention. Those skilled in the art can think of other specific implementations of the present invention without creative work, and these methods will fall within the protection scope of the present invention.

Claims

1. A fully digital ignition device suitable for a large flow combustion simulator, characterized in that: It comprises a fuel valve control circuit, a single chip microcomputer, a high voltage ignition circuit and a spark plug connected in sequence, wherein a flame detection circuit is also arranged between the single chip microcomputer and the spark plug; the high voltage ignition circuit is used to generate a high voltage ignition pulse with adjustable frequency and pulse width on an ignition needle; the flame detection circuit is used to detect whether a flame exists on the detection needle; the fuel valve control circuit is used to synchronously control the fuel valve, and the fuel valve control circuit, the high voltage ignition circuit and the flame detection circuit are controlled by the single chip microcomputer.

2. A fully digital ignition device suitable for a large flow combustion simulator as claimed in claim 1, characterized in that: The working process of the high-voltage ignition circuit is as follows: after the single-chip microcomputer generates a PWM waveform, it drives the power transformer to work through the push-pull amplifier circuit, and obtains an AC voltage at the secondary of the power transformer. The AC voltage charges the energy storage capacitor through the rectifier diode, and the AC voltage is detected by a voltage regulator diode. Once the voltage amplitude is greater than the diode breakdown voltage, the diode breakdown triggers the high-voltage thyristor to turn on. At this time, the voltage on the energy storage capacitor will be directly applied to the primary coil of the high-voltage package through the high-voltage thyristor, and the secondary coil of the high-voltage package will immediately induce a high voltage of 15kV~20kV, and this high-voltage signal will be discharged through the spark plug probe.

3. A fully digital ignition device suitable for a large flow combustion simulator as claimed in claim 1, characterized in that: The working process of the flame detection circuit is as follows: a PWM wave for detection is generated by a single-chip microcomputer, and a transformer is driven by a push-pull amplifier circuit. An AC voltage signal with adjustable frequency and pulse width is generated at the secondary end of the transformer, and is applied to the detection probe as a detection voltage. By utilizing the unidirectional conductivity of flame ions, if a flame exists, the AC voltage signal will be rectified. At this time, a negative voltage is obtained at one end of the flame. After filtering, the negative voltage is sent to a comparator for voltage comparison. The output level of the comparator is detected by the single-chip microcomputer. When the comparator output is a low level, it indicates that a flame exists, and the single-chip microcomputer determines that the ignition is successful.

4. A fully digital ignition device suitable for a large flow combustion simulator as claimed in claim 1, characterized in that: The working process of the fuel valve control circuit is as follows: the single chip microcomputer automatically controls the fuel valve through ignition and flame detection to avoid leakage of the fuel valve; the single chip microcomputer opens the air intake fan for pre-purge, then sends an ignition pulse, and then opens the fuel valve. The fuel will be immediately ignited after mixing with the intake air after passing through the fuel valve. At this time, the single chip microcomputer detects whether the ignition is successful through the flame detection circuit. If successful, it enters the real-time flame detection state. If the ignition fails or the flame is accidentally extinguished, the fuel valve is immediately closed and an alarm signal is issued to avoid fuel leakage.

5. A fully digital ignition device suitable for a large flow combustion simulator as claimed in claim 1, characterized in that: The high-voltage pulse ignition circuit includes a transformer and an energy storage capacitor; a PWM wave is generated by a single-chip microcomputer, which drives the transformer to work after amplification, and a high voltage is induced at the output end of the transformer. The energy storage capacitor is charged after rectification, and the energy storage capacitor is used to drive the high-voltage package to generate an ignition pulse.

6. A fully digital ignition device suitable for a large flow combustion simulator as claimed in claim 1, characterized in that: The spark plug acts as a discharge and flame detection probe.

7. A fully digital ignition device suitable for a large flow combustion simulator as claimed in claim 1, characterized in that: The flame detection circuit includes a transformer, a detection power rectifier, and a comparator; a PWM waveform is generated by a single chip microcomputer to drive the transformer, and an AC power supply with adjustable frequency and pulse width is generated at the secondary of the transformer. The AC power supply reaches the detection probe to detect whether a flame exists.

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