Natural gas engine misfire identification method, device and storage medium

Abstract

The application provides a natural gas engine misfire identification method, device and storage medium. The method comprises the following steps: obtaining a first engine speed change rate and a voltage change rate of a rear oxygen sensor; when the first speed change rate is greater than a speed change rate threshold and the voltage change rate is greater than a voltage change rate threshold, preliminarily determining a misfire state, adjusting an exhaust gas recirculation valve opening degree, obtaining a second speed change rate and a voltage rise rate, or obtaining an engine knock protection ignition angle; when it is determined that the second speed change rate is within a preset speed change rate range, the voltage rise rate is greater than a rise rate threshold, and the difference between the corresponding voltage rise rates in different time periods is less than a preset difference, or when it is determined that the knock protection ignition angle changes to a maximum ignition angle, the exhaust gas recirculation valve is stopped adjusting, and the misfire state is finally determined. The problem that the prior art is difficult to identify misfire in the whole vehicle transient acceleration condition due to too lean mixture is solved.

Description

Technical Field

[0001] This application relates to the field of natural gas engine misfire detection technology, and more specifically, to a natural gas engine misfire detection method, apparatus, storage medium, and electronic equipment. Background Technology

[0002] Misfire is a common failure mode in engines, especially natural gas engines. During a misfire, unburned air-fuel mixture enters the aftertreatment system and burns inside. Frequent misfires can cause the aftertreatment system to overheat and burn out. Even isolated misfires can produce large amounts of harmful gases, polluting the atmosphere. When a vehicle is operating under transient loading conditions, a misfire can cause abnormal noises and insufficient power. When a vehicle is operating under frequent acceleration conditions and a severe misfire occurs, it can damage aftertreatment components, or even result in vehicle damage or personal injury.

[0003] Existing methods for identifying or diagnosing misfires use crankshaft speed fluctuation identification and cylinder pressure identification.

[0004] The crankshaft speed fluctuation identification method works as follows: When the engine is operating normally, the crankshaft undergoes acceleration and deceleration processes due to normal compression and power strokes. A misfire prevents the misfired cylinder from performing its normal work, resulting in a lack of proper acceleration and deceleration and significant speed fluctuations. A crankshaft position sensor monitors these changes in crankshaft rotation; when the crankshaft rotation time exceeds a set limit, a misfire is detected. However, this method has stringent misfire detection conditions, requiring continuous monitoring of crankshaft rotation. If the calibration limits are too strict, it can lead to numerous false misfires. Therefore, this method is suitable for misfire identification under steady-state conditions or prolonged misfire identification under transient conditions, but it is more difficult to identify misfires caused by an overly lean air-fuel mixture during transient acceleration. Summary of the Invention

[0005] The main objective of this application is to provide a method, device, storage medium, and electronic device for identifying misfires in natural gas engines, so as to at least solve the problem that the existing technology is difficult to identify misfires due to excessively lean air-fuel mixtures during transient acceleration of a vehicle.

[0006] To achieve the above objectives, according to one aspect of this application, a method for identifying misfires in a natural gas engine is provided, comprising: acquiring a first rate of change of engine speed and a voltage rate of change of a rear oxygen sensor of a natural gas vehicle; determining whether the first rate of change of engine speed is greater than a rate of change of engine speed threshold, and determining whether the voltage rate of change of engine speed is greater than a voltage rate of change of engine speed threshold; if it is determined that the first rate of change of engine speed is greater than the rate of change of engine speed threshold, and the voltage rate of change of engine speed is greater than the voltage rate of change of engine speed threshold, preliminarily determining that the engine is in a misfire state, and adjusting the opening of the exhaust gas recirculation valve, and acquiring a second rate of change of engine speed and a voltage rise rate of the rear oxygen sensor, or acquiring the ignition angle of the engine's knock protection, during the adjustment of the opening of the exhaust gas recirculation valve; if it is determined that the second rate of change of engine speed is within a preset rate of change of engine speed, and the voltage rise rate is greater than a rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than a preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, stopping the adjustment of the opening of the exhaust gas recirculation valve, and finally determining that the engine is in the misfire state.

[0007] Optionally, adjusting the opening of the exhaust gas recirculation valve includes: when it is initially determined that the engine is in the misfire state, reducing the opening of the exhaust gas recirculation valve by a preset step size.

[0008] Optionally, after initially determining that the engine is in a misfire state, the method further includes: generating a prompt message, wherein the prompt message is used to indicate that the probability of the engine of the natural gas vehicle being in the misfire state is greater than a first probability; after finally determining that the engine is in the misfire state, the method further includes: generating an alarm message, wherein the alarm message is used to indicate that the probability of the engine of the natural gas vehicle being in the misfire state is greater than a second probability, and the second probability is greater than the first probability.

[0009] Optionally, after adjusting the opening of the exhaust gas recirculation valve and obtaining the second engine speed change rate and the voltage rise rate of the rear oxygen sensor during the adjustment of the exhaust gas recirculation valve opening, the method further includes: continuing to adjust the opening of the exhaust gas recirculation valve if it is determined that the second speed change rate is not within the preset speed change rate range, and / or the voltage rise rate is less than or equal to the rise rate threshold, and / or the difference between the voltage rise rates corresponding to different time periods is greater than or equal to a preset difference.

[0010] Optionally, after finally determining that the engine is in the misfire state, the method further includes: determining the cause of the failure that caused the engine to be in the misfire state, wherein the cause of the failure includes at least one of ignition system failure, gas supply system failure, abnormal air-fuel ratio failure, and insufficient cylinder pressure failure.

[0011] Optionally, obtaining the first speed change rate of the engine of the natural gas vehicle and the voltage change rate of the rear oxygen sensor includes: obtaining the first speed change rate of the engine of the natural gas vehicle and the voltage change rate of the rear oxygen sensor after gear shifting.

[0012] Optionally, before acquiring the first speed change rate of the engine and the voltage change rate of the rear oxygen sensor of the natural gas vehicle, the method further includes: acquiring the acceleration of the natural gas vehicle, determining whether the acceleration is greater than an acceleration threshold; and if the acceleration is determined to be greater than the acceleration threshold, determining that the natural gas vehicle is operating in a transient acceleration condition.

[0013] According to another aspect of this application, a natural gas engine misfire detection device is provided, comprising: an acquisition unit for acquiring a first speed change rate of an engine in a natural gas vehicle and a voltage change rate of a rear oxygen sensor; a first determination unit for determining whether the first speed change rate is greater than a speed change rate threshold and whether the voltage change rate is greater than a voltage change rate threshold; and a second determination unit for, if it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, initially determining that the engine is in a misfire state, and adjusting the opening of the exhaust gas recirculation valve, and adjusting... The third determining unit is used to obtain the second engine speed change rate and the voltage rise rate of the rear oxygen sensor during the process of adjusting the opening of the exhaust gas recirculation valve, or to obtain the ignition angle of the engine's knock protection; the third determining unit is used to stop adjusting the opening of the exhaust gas recirculation valve and finally determine that the engine is in the misfire state when it is determined that the second speed change rate is within a preset speed change rate range, and the voltage rise rate is greater than the rise rate threshold, and the difference between the voltage rise rates corresponding to different time periods is less than a preset difference, or when it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle.

[0014] According to another aspect of this application, the computer-readable storage medium is provided to include a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform any of the aforementioned natural gas engine misfire detection methods.

[0015] According to another aspect of this application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing any of the described natural gas engine misfire detection methods.

[0016] Applying the technical solution of this application, the first speed change rate of the engine and the voltage change rate of the rear oxygen sensor of the natural gas vehicle are obtained; it is determined whether the first speed change rate is greater than a speed change rate threshold, and whether the voltage change rate is greater than a voltage change rate threshold; if it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted, and during the adjustment of the opening of the exhaust gas recirculation valve, the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained; if it is determined that the second speed change rate is within a preset speed change rate range, and the voltage rise rate is greater than the rise rate threshold, and the difference in the corresponding voltage rise rates in different time periods is less than a preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, the adjustment of the exhaust gas recirculation valve is stopped, and the engine is finally determined to be in a misfire state. This system utilizes existing engine parameter change signals, namely engine speed and rear oxygen sensor voltage, to initially determine misfire during transient acceleration. After initial misfire detection, the exhaust gas recirculation (EGR) valve's adaptive adjustment function is enabled until the engine speed fluctuation gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. This method accurately identifies misfires during transient acceleration, significantly reducing false alarms. It accurately identifies misfires caused by an excessively lean air-fuel mixture during transient acceleration, resolving the problem promptly and effectively. This addresses the difficulty of identifying misfires caused by an excessively lean air-fuel mixture during transient acceleration in existing technologies, preventing damage to components or the vehicle, and avoiding personal injury. Furthermore, the EGR valve's adaptive adjustment function automatically stops after misfire detection. The electronic control logic is simple, requiring no additional components or sensors, making it easy to operate and implement without increasing costs. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 A hardware structure block diagram of a mobile terminal for performing a natural gas engine misfire detection method according to an embodiment of this application is shown.

[0019] Figure 2 A schematic flowchart of a natural gas engine misfire detection method according to an embodiment of this application is shown.

[0020] Figure 3 A schematic diagram of the misfire path spectrum of a vehicle under transient acceleration conditions, provided by an embodiment of this application, is shown.

[0021] Figure 4 A schematic diagram of the normal road spectrum of a vehicle under transient acceleration conditions, provided by an embodiment of this application, is shown.

[0022] Figure 5 A schematic diagram of an engine misfire detection logic provided according to an embodiment of this application is shown;

[0023] Figure 6 A schematic diagram of the adaptive regulation logic of the EGR valve provided according to an embodiment of this application is shown;

[0024] Figure 7 A structural block diagram of a natural gas engine misfire detection device provided according to an embodiment of this application is shown. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application:

[0029] Natural gas engine misfire: refers to the phenomenon of uneven combustion or failure to burn the air-fuel mixture in the engine cylinder.

[0030] Post-oxygen sensor: The post-oxygen sensor is an important component that accurately measures the oxygen concentration of exhaust gas after combustion in a natural gas engine and after it has been purified by aftertreatment. It transmits the oxygen concentration signal and feeds it back to the engine ECU, enabling the engine to achieve closed-loop control with a certain excess air coefficient as the target.

[0031] Exhaust Gas Recirculation (EGR) valve: An EGR valve is a device used to control the recirculation of exhaust gases in an internal combustion engine. By reintroducing a portion of the exhaust gases into the engine, the EGR valve lowers the temperature inside the engine combustion chamber, reduces the formation of nitrogen oxides, and thus effectively reduces harmful substances in exhaust emissions. This helps improve air quality and reduce the vehicle's environmental impact. The EGR valve also helps reduce engine fuel consumption and improve fuel economy. The EGR valve is an important component of modern internal combustion engine emission control systems.

[0032] As described in the background section, existing technologies have difficulty identifying misfires caused by an overly lean air-fuel mixture during transient acceleration of a vehicle. To address this problem, embodiments of this application provide a method, apparatus, storage medium, and electronic device for identifying misfires in a natural gas engine.

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for a natural gas engine misfire detection method according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0035] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the natural gas engine misfire identification method in this embodiment of the invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the aforementioned networks may include wireless networks provided by the mobile terminal's communication provider. In one example, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0036] This embodiment provides a method for identifying a natural gas engine misfire that runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0037] Figure 2 This is a flowchart of a natural gas engine misfire detection method according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0038] Step S201: Obtain the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle.

[0039] The post-oxygen sensor is installed in the aftertreatment outlet pipeline and is a crucial component for monitoring aftertreatment efficiency. It compares the oxygen concentration reading with that of the pre-oxygen sensor (installed before the aftertreatment). Normally, the pre-oxygen sensor will show a slightly higher oxygen concentration. When the oxygen concentrations measured by both sensors are almost identical, it indicates aftertreatment failure. The oxygen concentration in the exhaust gas can be reflected by the voltage value of the post-oxygen sensor. A lower voltage value indicates a higher oxygen concentration, resulting in a lean mixture; conversely, a higher voltage value indicates a lower oxygen concentration, resulting in a rich mixture. Both excessively rich and lean mixtures can lead to engine misfire.

[0040] Specifically, the rate of change of engine speed is determined based on the engine speed of the natural gas vehicle. The rate of change of engine speed is calculated as: (Second engine speed - First engine speed) / Change time. For example, if the engine speed is 500 r / s in the first second and 530 r / s in the second second, then the rate of change of engine speed is 30 r / s. 2 The voltage change rate of the post-oxygen sensor is determined based on the voltage value of the post-oxygen sensor. The voltage change rate is (second voltage - first voltage) / change time. For example, if the voltage of the post-oxygen sensor is 1.8V in the 1st second and 0.8V in the 2nd second, then the voltage change rate is 1V / s.

[0041] Step S202: Determine whether the first speed change rate is greater than the speed change rate threshold, and determine whether the voltage change rate is greater than the voltage change rate threshold.

[0042] The threshold for the rate of change of rotational speed can be set to 15 r / s. 2 20r / s 2 25r / s 2 The voltage change rate threshold can be set to 0.8V / s, 1V / s, or 1.5V / s.

[0043] Step S203: If it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted. During the process of adjusting the opening of the exhaust gas recirculation valve, the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained.

[0044] Based on the engine's working principle and design, the ignition angle for knock protection is typically located near the engine's timing point, generally between 15° and 20°. This ignition angle ensures proper combustion of fuel within the cylinder, preventing knocking and protecting the engine's normal operation and the safety of its components.

[0045] Specifically, when the vehicle is operating under transient acceleration conditions, if the engine speed fluctuation rate shows an increasing trend shortly after gear shifting (see...), Figure 3 (at point a in the text), and the oxygen sensor voltage showed significant fluctuations (see...). Figure 3 If points b and c are detected, it is initially determined to be a fire, and the EGR valve opening adaptive adjustment function is used for further judgment.

[0046] Step S204: If it is determined that the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than the preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, the opening of the exhaust gas recirculation valve is stopped, and the engine is finally determined to be in a misfire state.

[0047] The voltage rise rate threshold of the post-oxygen sensor can be set to 1V / s or 1.2V / s, and the preset difference can be set to 0.1V / s.

[0048] Specifically, during the further judgment process using the EGR valve opening adaptive adjustment function, if the speed fluctuation rate gradually decreases to a stable state and the rear oxygen sensor voltage rises smoothly and rapidly during transient acceleration, or if the EGR valve opening continuously decreases until the ignition angle of the knock protection reaches its maximum, the adjustment of the EGR valve opening is stopped, indicating that the vehicle has a misfire phenomenon under transient acceleration conditions.

[0049] In this embodiment, the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle are obtained; it is determined whether the first engine speed change rate is greater than a speed change rate threshold, and whether the voltage change rate is greater than a voltage change rate threshold; if it is determined that the first engine speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted. During the adjustment of the exhaust gas recirculation valve opening, the second engine speed change rate and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained; if it is determined that the second engine speed change rate is within a preset speed change rate range, and the voltage rise rate is greater than the rise rate threshold, and the difference in the corresponding voltage rise rates in different time periods is less than a preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, the adjustment of the exhaust gas recirculation valve opening is stopped, and the engine is finally determined to be in a misfire state. This system utilizes existing engine parameter change signals, namely engine speed and rear oxygen sensor voltage, to initially determine misfire during transient acceleration. After initial misfire detection, the exhaust gas recirculation (EGR) valve's adaptive adjustment function is enabled until the engine speed fluctuation gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. This method accurately identifies misfires during transient acceleration, significantly reducing false alarms. It accurately identifies misfires caused by an excessively lean air-fuel mixture during transient acceleration, resolving the problem promptly and effectively. This addresses the difficulty of identifying misfires caused by an excessively lean air-fuel mixture during transient acceleration in existing technologies, preventing damage to components or the vehicle, and avoiding personal injury. Furthermore, the EGR valve's adaptive adjustment function automatically stops after misfire detection. The electronic control logic is simple, requiring no additional components or sensors, making it easy to operate and implement without increasing costs.

[0050] In the specific implementation process, the above step S203 adjusts the opening of the exhaust gas recirculation valve, including: when it is initially determined that the engine is in a misfire state, reducing the opening of the exhaust gas recirculation valve by a preset step size.

[0051] The preset step size can be set to 2%, 3%, or 4%.

[0052] This method is enabled after a preliminary misfire is detected. Its function is to further determine whether the misfire is caused by an overly lean air-fuel mixture during transient loading based on the reduction of the EGR valve opening. The adaptive adjustment function logic of the EGR valve is described as follows: During the transient acceleration of the vehicle, if there is no engine fault, the preliminary identification of misfire under transient acceleration is enabled. Then, in the next transient acceleration condition, the EGR valve decreases in steps of 2% until the engine speed fluctuation rate gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. Then, the adjustment stops. Alternatively, the adjustment stops as the EGR valve opening continues to decrease until the ignition angle of the knock protection reaches its maximum.

[0053] Specifically, after initially determining that the engine is in a misfire state, the method further includes: generating a prompt message, wherein the prompt message is used to indicate that the probability of the engine of the natural gas vehicle being in a misfire state is greater than a first probability; after finally determining that the engine is in a misfire state, the method further includes: generating an alarm message, wherein the alarm message is used to indicate that the probability of the engine of the natural gas vehicle being in a misfire state is greater than a second probability, and the second probability is greater than the first probability.

[0054] The first probability can be set to 60%, 70%, or 80%, and the second probability can be set to 90% or 95%.

[0055] More specifically, after adjusting the opening of the exhaust gas recirculation valve and obtaining the second engine speed change rate and the voltage rise rate of the rear oxygen sensor during the adjustment of the exhaust gas recirculation valve opening, the method further includes: if it is determined that the second speed change rate is not within the preset speed change rate range, and / or the voltage rise rate is less than or equal to the rise rate threshold, and / or the difference in the voltage rise rates corresponding to different time periods is greater than or equal to a preset difference, then continue to adjust the opening of the exhaust gas recirculation valve.

[0056] This method can only determine that the engine is in a misfire state if the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the corresponding voltage rise rate in different time periods is less than the preset difference. Otherwise, the opening of the exhaust gas recirculation valve will continue to be reduced in 2% increments.

[0057] Furthermore, after finally determining that the engine is in a misfire state, the method also includes: determining the cause of the fault that caused the engine to be in a misfire state, wherein the cause of the fault includes at least one of the following: ignition system fault, gas supply system fault, abnormal air-fuel ratio fault, and insufficient cylinder pressure fault.

[0058] Ignition system malfunctions include: aging ignition coil, abnormal spark plug gap, etc.

[0059] Gas supply system malfunctions include: abnormal gas injection valve supply pressure, injection valve circuit malfunction, etc.

[0060] Abnormal air-fuel ratio faults include: an overly rich or overly lean mixture of air and fuel;

[0061] Insufficient cylinder pressure can be caused by: valve train malfunction, poor piston-cylinder liner sealing, etc.

[0062] Furthermore, the first speed change rate of the engine of the natural gas vehicle and the voltage change rate of the rear oxygen sensor are obtained, including: obtaining the first speed change rate of the engine of the natural gas vehicle and the voltage change rate of the rear oxygen sensor after gear shift.

[0063] Specifically, before obtaining the first speed change rate of the engine and the voltage change rate of the rear oxygen sensor of the natural gas vehicle, the method further includes: obtaining the acceleration of the natural gas vehicle and determining whether the acceleration is greater than an acceleration threshold; if the acceleration is determined to be greater than the acceleration threshold, determining that the natural gas vehicle is operating in a transient acceleration condition.

[0064] The acceleration threshold can be set according to the current gear of the natural gas vehicle. Different gears correspond to different acceleration thresholds, and a MAP table between different gears and acceleration thresholds can be constructed.

[0065] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the natural gas engine misfire detection method of this application will be described in detail below with reference to specific embodiments.

[0066] A natural gas engine is an engine that uses natural gas as fuel. Natural gas engines can be either internal combustion engines or gas turbines. Internal combustion engines use natural gas as fuel and generate power through compression and ignition; while gas turbines use natural gas for direct combustion to generate power. Natural gas engines are commonly used in generator sets, industrial equipment, and transportation vehicles. Because natural gas is a relatively clean fuel, natural gas engines are considered an environmentally friendly power option.

[0067] There are several existing methods for identifying or diagnosing misfires, the conventional ones being crankshaft speed fluctuation identification and cylinder pressure identification.

[0068] The crankshaft speed fluctuation identification method works as follows: When the engine is operating normally, the crankshaft undergoes acceleration and deceleration processes due to normal compression and power strokes. A misfire prevents the misfired cylinder from performing its normal work, resulting in a lack of proper acceleration and deceleration and significant speed fluctuations. A crankshaft position sensor monitors these changes in crankshaft rotation; when the crankshaft rotation time exceeds a set limit, a misfire is detected. However, this method has stringent misfire detection conditions, requiring continuous monitoring of crankshaft rotation. If the calibration limits are too strict, it can lead to numerous false misfires. Therefore, this method is suitable for misfire identification under steady-state conditions or prolonged misfire identification under transient conditions, but it is more difficult to identify misfires caused by an overly lean air-fuel mixture during transient acceleration.

[0069] The principle of cylinder pressure detection is as follows: the pressure inside the engine cylinder is directly related to combustion; therefore, changes in cylinder pressure can be monitored to identify whether the engine has misfired. Under high-speed, high-load conditions, the cylinder pressure of the misfired cylinder differs significantly from that during normal combustion, making misfire detection relatively easy. However, under low-speed, low-load conditions, the cylinder pressure difference is no longer significant, requiring cylinder pressure sensors to be installed in each cylinder for detection. Therefore, in practical applications, this method is inconvenient to install and costly.

[0070] This embodiment relates to a specific method for identifying a misfire in a natural gas engine. Figure 5 This is a logic diagram for determining engine misfire. Figure 6 The adaptive control logic diagram for the EGR valve is as follows: Figure 5 and Figure 6 As shown, it specifically includes the following:

[0071] The post-oxygen sensor is installed in the aftertreatment outlet pipeline and is a crucial component for monitoring aftertreatment efficiency. It compares the oxygen concentration reading with that of the pre-oxygen sensor (installed before the aftertreatment). Normally, the pre-oxygen sensor will show a slightly higher oxygen concentration. When the oxygen concentrations measured by both sensors are almost identical, it indicates aftertreatment failure. The oxygen concentration in the exhaust gas can be reflected by the voltage value of the post-oxygen sensor. A lower voltage value indicates a higher oxygen concentration, resulting in a lean mixture; conversely, a higher voltage value indicates a lower oxygen concentration, resulting in a rich mixture. Both excessively rich and lean mixtures can lead to engine misfire.

[0072] When the vehicle is operating under transient acceleration conditions, if the engine speed fluctuation rate shows an increasing trend shortly after gear shift (see...) Figure 3 As shown at point a), and the oxygen sensor voltage fluctuated significantly (see...). Figure 3 As shown at points b and c), the initial judgment is a fire; further judgment is made using the EGR valve opening adaptive adjustment function, such as... Figure 5 As shown, during transient acceleration, if the speed fluctuation rate gradually decreases to a stable level and the oxygen sensor voltage rises smoothly and rapidly, see... Figure 4 If the vehicle exhibits normal road pattern behavior, it can be determined that there is a misfire phenomenon during transient acceleration.

[0073] The EGR valve adaptive adjustment function operates under transient conditions and is enabled after an initial misfire is detected. Its function is to further determine whether the misfire is caused by an excessively lean air-fuel mixture during transient loading based on the reduction of the EGR valve opening. The EGR valve adaptive adjustment logic diagram is as follows: Figure 6 As shown. The adaptive adjustment function logic of the EGR valve is described as follows: During the transient acceleration of the vehicle, if the engine is fault-free and the initial identification of misfire in the transient acceleration condition is enabled, the EGR valve will decrease in step size of 2% in the next transient acceleration condition until the engine speed fluctuation rate gradually decreases to a stable state and the voltage of the rear oxygen sensor rises smoothly and rapidly. Then the adjustment will stop. Alternatively, the adjustment will stop as the opening of the EGR valve continues to decrease until the ignition angle of the knock protection returns to its maximum.

[0074] 1) Preliminary misfire identification: When the vehicle is running under transient acceleration conditions, if the engine speed fluctuation rate shows an increasing trend in a short period of time and the rear oxygen sensor voltage shows obvious fluctuations, then a misfire is preliminarily determined.

[0075] 2) Further misfire identification: After a preliminary misfire is determined, the EGR valve adaptive adjustment function is activated under transient conditions. When the engine speed fluctuation rate gradually decreases to a stable level and the oxygen sensor voltage rises smoothly and rapidly, it is determined to be a misfire under acceleration conditions.

[0076] 3) EGR valve adaptive adjustment function: During the transient acceleration of the vehicle, if the engine is fault-free and the transient acceleration condition misfire is initially identified and enabled, the EGR valve will decrease in step size of 2% in the next transient acceleration condition until the engine speed fluctuation rate gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly.

[0077] The embodiments of this application utilize existing engine parameter change signals, namely engine speed and rear oxygen sensor voltage value, to initially determine misfire during transient acceleration of the vehicle. After the initial misfire determination, the adaptive adjustment function of the exhaust gas recirculation valve is enabled until the engine speed fluctuation rate gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. At this point, a misfire is finally determined. This method can accurately determine misfire problems during transient processes and greatly reduces misfire false alarms. It accurately identifies misfire phenomena caused by an excessively lean air-fuel mixture during transient acceleration of the vehicle, and resolves the misfire problem in a timely and effective manner. This solves the problem of difficulty in identifying misfires caused by an excessively lean air-fuel mixture during transient acceleration of the vehicle in existing technologies, avoiding damage to the aforementioned components or vehicle and personal injury. In addition, the adaptive adjustment function of the EGR valve can automatically stop after a misfire is determined. The electronic control logic is simple, requiring no additional components or sensors, making it easy to operate and implement without increasing costs.

[0078] This application also provides a natural gas engine misfire detection device. It should be noted that the natural gas engine misfire detection device of this application can be used to execute the natural gas engine misfire detection method provided in this application. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0079] The following describes the natural gas engine misfire detection device provided in the embodiments of this application.

[0080] Figure 7 This is a schematic diagram of a natural gas engine misfire detection device according to an embodiment of this application. Figure 7 As shown, the device includes: an acquisition unit 71, a first determination unit 72, a second determination unit 73, and a third determination unit 74.

[0081] Acquisition unit 71 is used to acquire the first speed change rate of the engine and the voltage change rate of the rear oxygen sensor of the natural gas vehicle.

[0082] Specifically, the rate of change of engine speed is determined based on the engine speed of the natural gas vehicle. The rate of change of engine speed is calculated as: (Second engine speed - First engine speed) / Change time. For example, if the engine speed is 500 r / s in the first second and 530 r / s in the second second, then the rate of change of engine speed is 30 r / s. 2The voltage change rate of the post-oxygen sensor is determined based on the voltage value of the post-oxygen sensor. The voltage change rate is (second voltage - first voltage) / change time. For example, if the voltage of the post-oxygen sensor is 1.8V in the 1st second and 0.8V in the 2nd second, then the voltage change rate is 1V / s.

[0083] The first determining unit 72 is used to determine whether the first speed change rate is greater than the speed change rate threshold and to determine whether the voltage change rate is greater than the voltage change rate threshold.

[0084] The threshold for the rate of change of rotational speed can be set to 15 r / s. 2 20r / s 2 25r / s 2 The voltage change rate threshold can be set to 0.8V / s, 1V / s, or 1.5V / s.

[0085] The second determining unit 73 is used to initially determine that the engine is in a misfire state when the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, and to adjust the opening of the exhaust gas recirculation valve, and to obtain the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor during the process of adjusting the opening of the exhaust gas recirculation valve, or to obtain the ignition angle of the engine knock protection.

[0086] Based on the engine's working principle and design, the ignition angle for knock protection is typically located near the engine's timing point, generally between 15° and 20°. This ignition angle ensures proper combustion of fuel within the cylinder, preventing knocking and protecting the engine's normal operation and the safety of its components.

[0087] Specifically, when the vehicle is operating under transient acceleration conditions, if the engine speed fluctuation rate shows an increasing trend shortly after shifting gears, and the rear oxygen sensor voltage shows significant fluctuations, it is initially judged to be a misfire, and the EGR valve opening adaptive adjustment function is used for further judgment.

[0088] The third determining unit 74 is used to stop adjusting the opening of the exhaust gas recirculation valve and finally determine that the engine is in a misfire state when the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than the preset difference, or when the ignition angle of the knock protection changes to the maximum ignition angle.

[0089] The voltage rise rate threshold of the post-oxygen sensor can be set to 1V / s or 1.2V / s, and the preset difference can be set to 0.1V / s.

[0090] Specifically, during the further judgment process using the EGR valve opening adaptive adjustment function, if the speed fluctuation rate gradually decreases to a stable state and the rear oxygen sensor voltage rises smoothly and rapidly during transient acceleration, or if the EGR valve opening continuously decreases until the ignition angle of the knock protection reaches its maximum, the adjustment of the EGR valve opening is stopped, indicating that the vehicle has a misfire phenomenon under transient acceleration conditions.

[0091] In this embodiment, the acquisition unit is used to acquire the first speed change rate of the engine and the voltage change rate of the rear oxygen sensor of the natural gas vehicle; the first determination unit is used to determine whether the first speed change rate is greater than a speed change rate threshold and whether the voltage change rate is greater than a voltage change rate threshold; the second determination unit is used to initially determine that the engine is in a misfire state when the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, and adjust the opening of the exhaust gas recirculation valve, and acquire the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor during the adjustment of the exhaust gas recirculation valve opening, or acquire the ignition angle of the engine knock protection; the third determination unit is used to stop adjusting the opening of the exhaust gas recirculation valve and finally determine that the engine is in a misfire state when the second speed change rate is within a preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the corresponding voltage rise rates in different time periods is less than a preset difference, or when the ignition angle of the knock protection changes to the maximum ignition angle. By utilizing existing engine parameter change signals, namely engine speed and rear oxygen sensor voltage value, a preliminary determination of misfire during transient acceleration is made. After the initial misfire determination, the adaptive adjustment function of the exhaust gas recirculation valve is enabled until the engine speed fluctuation rate gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. At this point, a misfire is finally determined. This method can accurately determine misfire problems during transient processes and greatly reduces false misfires. It accurately identifies misfires caused by an excessively lean air-fuel mixture during transient acceleration, and resolves the misfire problem in a timely and effective manner. This solves the problem of difficulty in identifying misfires caused by an excessively lean air-fuel mixture during transient acceleration in existing technologies, avoiding damage to the aforementioned components or vehicle and personal injury. In addition, the adaptive adjustment function of the EGR valve can automatically stop after a misfire is determined. The electronic control logic is simple, requiring no additional components or sensors, making it easy to operate and implement without increasing costs.

[0092] As an alternative, the second determining unit includes a reduction module for reducing the opening of the exhaust gas recirculation valve by a preset step size when it is initially determined that the engine is in a misfire state.

[0093] Specifically, after a preliminary misfire is detected, the EGR valve is activated. Its function is to further determine whether the misfire is caused by an overly lean air-fuel mixture during transient loading based on the reduction of the EGR valve opening. The adaptive adjustment function logic of the EGR valve is described as follows: During the transient acceleration of the vehicle, if there is no engine fault, the preliminary identification of misfire under transient acceleration is activated. Then, in the next transient acceleration condition, the EGR valve decreases in steps of 2% until the engine speed fluctuation rate gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. Then, the adjustment stops. Alternatively, the adjustment stops as the EGR valve opening continues to decrease until the ignition angle of the knock protection reaches its maximum.

[0094] In one optional embodiment, the device further includes a first generating unit and a second generating unit. The first generating unit is used to generate a prompt message after initially determining that the engine is in a misfire state, wherein the prompt message is used to indicate that the probability of the engine of the natural gas vehicle being in a misfire state is greater than a first probability. The second generating unit is used to generate an alarm message after finally determining that the engine is in a misfire state, wherein the alarm message is used to indicate that the probability of the engine of the natural gas vehicle being in a misfire state is greater than a second probability, and the second probability is greater than the first probability.

[0095] The first probability can be set to 60%, 70%, or 80%, and the second probability can be set to 90% or 95%.

[0096] In one optional embodiment, the device further includes an adjustment unit for adjusting the opening of the exhaust gas recirculation valve. After obtaining the second engine speed change rate and the voltage rise rate of the rear oxygen sensor during the adjustment of the exhaust gas recirculation valve opening, the device continues to adjust the exhaust gas recirculation valve opening if it is determined that the second speed change rate is not within a preset speed change rate range, and / or the voltage rise rate is less than or equal to a rise rate threshold, and / or the difference in voltage rise rates corresponding to different time periods is greater than or equal to a preset difference.

[0097] Specifically, the engine can only be determined to be in a misfire state if the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the corresponding voltage rise rate in different time periods is less than the preset difference. Otherwise, the opening of the exhaust gas recirculation valve will continue to decrease in 2% increments.

[0098] In one alternative embodiment, the device further includes a fourth determining unit, used to determine the cause of the engine misfire after finally determining that the engine is in a misfire state, wherein the cause of the misfire includes at least one of ignition system failure, gas supply system failure, abnormal air-fuel ratio failure, and insufficient cylinder pressure failure.

[0099] Ignition system malfunctions include: aging ignition coil, abnormal spark plug gap, etc.

[0100] Gas supply system malfunctions include: abnormal gas injection valve supply pressure, injection valve circuit malfunction, etc.

[0101] Abnormal air-fuel ratio faults include: an overly rich or overly lean mixture of air and fuel;

[0102] Insufficient cylinder pressure can be caused by: valve train malfunction, poor piston-cylinder liner sealing, etc.

[0103] In one alternative, the acquisition unit includes an acquisition module for acquiring the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle after gear shift.

[0104] In one optional embodiment, the device further includes a fifth determining unit and a sixth determining unit. The fifth determining unit is used to acquire the acceleration of the natural gas vehicle before acquiring the first speed change rate of the engine and the voltage change rate of the rear oxygen sensor, and to determine whether the acceleration is greater than an acceleration threshold. The sixth determining unit is used to determine that the natural gas vehicle is operating in a transient acceleration condition if the acceleration is determined to be greater than the acceleration threshold.

[0105] The acceleration threshold can be set according to the current gear of the natural gas vehicle. Different gears correspond to different acceleration thresholds, and a MAP table between different gears and acceleration thresholds can be constructed.

[0106] The natural gas engine fire detection device includes a processor and a memory. The aforementioned acquisition unit, first determination unit, second determination unit, and third determination unit are all stored as program units in the memory. The processor executes the aforementioned program units stored in the memory to achieve the corresponding functions. All of the above modules are located in the same processor; or, the above modules are located in different processors in any combination.

[0107] The processor contains a kernel, which retrieves the corresponding program unit from memory. One or more kernels can be configured, and adjusting kernel parameters can address the difficulty in misfire detection caused by an excessively lean air-fuel mixture during transient acceleration in a vehicle, a problem that is currently difficult to solve.

[0108] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0109] This invention provides a computer-readable storage medium including a stored program, wherein the program, when running, controls the device containing the computer-readable storage medium to execute the natural gas engine misfire detection method.

[0110] Specifically, the methods for identifying a natural gas engine misfire include:

[0111] Step S201: Obtain the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle.

[0112] Step S202: Determine whether the first speed change rate is greater than the speed change rate threshold, and determine whether the voltage change rate is greater than the voltage change rate threshold.

[0113] Step S203: If it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted. During the process of adjusting the opening of the exhaust gas recirculation valve, the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained.

[0114] Step S204: If it is determined that the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than the preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, the opening of the exhaust gas recirculation valve is stopped, and the engine is finally determined to be in a misfire state.

[0115] This invention provides a processor for running a program, wherein the program executes the natural gas engine misfire detection method during runtime.

[0116] Specifically, the methods for identifying a natural gas engine misfire include:

[0117] Step S201: Obtain the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle.

[0118] Step S202: Determine whether the first speed change rate is greater than the speed change rate threshold, and determine whether the voltage change rate is greater than the voltage change rate threshold.

[0119] Step S203: If it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted. During the process of adjusting the opening of the exhaust gas recirculation valve, the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained.

[0120] Step S204: If it is determined that the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than the preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, the opening of the exhaust gas recirculation valve is stopped, and the engine is finally determined to be in a misfire state.

[0121] This invention provides a device including a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs at least the following steps:

[0122] Step S201: Obtain the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle.

[0123] Step S202: Determine whether the first speed change rate is greater than the speed change rate threshold, and determine whether the voltage change rate is greater than the voltage change rate threshold.

[0124] Step S203: If it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted. During the process of adjusting the opening of the exhaust gas recirculation valve, the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained.

[0125] Step S204: If it is determined that the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than the preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, the opening of the exhaust gas recirculation valve is stopped, and the engine is finally determined to be in a misfire state.

[0126] The devices mentioned in this article can be servers, PCs, tablets, mobile phones, etc.

[0127] This application also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialization program having at least the following method steps:

[0128] Step S201: Obtain the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle.

[0129] Step S202: Determine whether the first speed change rate is greater than the speed change rate threshold, and determine whether the voltage change rate is greater than the voltage change rate threshold.

[0130] Step S203: If it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted. During the process of adjusting the opening of the exhaust gas recirculation valve, the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained.

[0131] Step S204: If it is determined that the second speed change rate is within the preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than the preset difference, or if it is determined that the ignition angle of the knock protection has changed to the maximum ignition angle, the opening of the exhaust gas recirculation valve is stopped, and the engine is finally determined to be in a misfire state.

[0132] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0133] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0134] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0135] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0136] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0137] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0138] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0139] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0140] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0141] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0142] 1) A natural gas engine misfire identification method according to this application includes: acquiring a first speed change rate of the engine of a natural gas vehicle and a voltage change rate of the rear oxygen sensor; determining whether the first speed change rate is greater than a speed change rate threshold and whether the voltage change rate is greater than a voltage change rate threshold; if the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, initially determining that the engine is in a misfire state, and adjusting the opening of the exhaust gas recirculation valve, and acquiring a second speed change rate of the engine and a voltage rise rate of the rear oxygen sensor, or acquiring the ignition angle of the engine's knock protection, during the adjustment of the exhaust gas recirculation valve opening; if the second speed change rate is within a preset speed change rate range, and the voltage rise rate is greater than a rise rate threshold, and the difference in the corresponding voltage rise rates in different time periods is less than a preset difference, or if the ignition angle of the knock protection changes to the maximum ignition angle, stopping the adjustment of the exhaust gas recirculation valve opening, and finally determining that the engine is in a misfire state. This system utilizes existing engine parameter change signals, namely engine speed and rear oxygen sensor voltage, to initially determine misfire during transient acceleration. After initial misfire detection, the exhaust gas recirculation (EGR) valve's adaptive adjustment function is enabled until the engine speed fluctuation gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. This method accurately identifies misfires during transient acceleration, significantly reducing false alarms. It accurately identifies misfires caused by an excessively lean air-fuel mixture during transient acceleration, resolving the problem promptly and effectively. This addresses the difficulty of identifying misfires caused by an excessively lean air-fuel mixture during transient acceleration in existing technologies, preventing damage to components or the vehicle, and avoiding personal injury. Furthermore, the EGR valve's adaptive adjustment function automatically stops after misfire detection. The electronic control logic is simple, requiring no additional components or sensors, making it easy to operate and implement without increasing costs.

[0143] 2) A natural gas engine misfire detection device according to this application includes: an acquisition unit for acquiring a first speed change rate of the engine of a natural gas vehicle and a voltage change rate of the rear oxygen sensor; a first determination unit for determining whether the first speed change rate is greater than a speed change rate threshold and whether the voltage change rate is greater than a voltage change rate threshold; a second determination unit for initially determining that the engine is in a misfire state when the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, and adjusting the opening of the exhaust gas recirculation valve, and acquiring a second speed change rate of the engine and a voltage rise rate of the rear oxygen sensor, or acquiring the ignition angle of the engine's knock protection, during the adjustment of the exhaust gas recirculation valve opening; and a third determination unit for stopping the adjustment of the exhaust gas recirculation valve opening and finally determining that the engine is in a misfire state when the second speed change rate is within a preset speed change rate range, the voltage rise rate is greater than a rise rate threshold, and the difference in the corresponding voltage rise rates in different time periods is less than a preset difference, or when the ignition angle of the knock protection changes to the maximum ignition angle. By utilizing existing engine parameter change signals, namely engine speed and rear oxygen sensor voltage value, a preliminary determination of misfire during transient acceleration is made. After the initial misfire determination, the adaptive adjustment function of the exhaust gas recirculation valve is enabled until the engine speed fluctuation rate gradually decreases to a stable level and the rear oxygen sensor voltage rises smoothly and rapidly. At this point, a misfire is finally determined. This method can accurately determine misfire problems during transient processes and greatly reduces false misfires. It accurately identifies misfires caused by an excessively lean air-fuel mixture during transient acceleration, and resolves the misfire problem in a timely and effective manner. This solves the problem of difficulty in identifying misfires caused by an excessively lean air-fuel mixture during transient acceleration in existing technologies, avoiding damage to the aforementioned components or vehicle and personal injury. In addition, the adaptive adjustment function of the EGR valve can automatically stop after a misfire is determined. The electronic control logic is simple, requiring no additional components or sensors, making it easy to operate and implement without increasing costs.

[0144] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for identifying a misfire in a natural gas engine, characterized in that, include: Obtain the first engine speed change rate and the voltage change rate of the rear oxygen sensor of the natural gas vehicle. Determine whether the first speed change rate is greater than a speed change rate threshold, and determine whether the voltage change rate is greater than a voltage change rate threshold; If it is determined that the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, it is initially determined that the engine is in a misfire state, and the opening of the exhaust gas recirculation valve is adjusted. During the process of adjusting the opening of the exhaust gas recirculation valve, the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor are obtained, or the ignition angle of the engine knock protection is obtained. If the second speed change rate is determined to be within the preset speed change rate range, and the voltage rise rate is greater than the rise rate threshold, and the difference in the voltage rise rate corresponding to different time periods is less than the preset difference, or if the ignition angle of the knock protection is determined to have changed to the maximum ignition angle, the opening of the exhaust gas recirculation valve is stopped, and the engine is finally determined to be in the misfire state.

2. The method according to claim 1, characterized in that, Adjusting the opening of the exhaust gas recirculation valve includes: If it is initially determined that the engine is in the misfire state, the opening of the exhaust gas recirculation valve is reduced by a preset step size.

3. The method according to claim 1, characterized in that, After initially determining that the engine is in a misfire state, the method further includes: generating a prompt message, wherein the prompt message is used to indicate that the probability that the engine of the natural gas vehicle is in the misfire state is greater than a first probability; After finally determining that the engine is in the misfire state, the method further includes: generating alarm information, wherein the alarm information is used to indicate that the probability that the engine of the natural gas vehicle is in the misfire state is greater than a second probability, and the second probability is greater than the first probability.

4. The method according to claim 1, characterized in that, After adjusting the opening of the exhaust gas recirculation valve, and acquiring the second engine speed change rate and the voltage rise rate of the after-oxygen sensor during the adjustment of the exhaust gas recirculation valve opening, the method further includes: If it is determined that the second speed change rate is not within the preset speed change rate range, and / or the voltage rise rate is less than or equal to the rise rate threshold, and / or the difference in the voltage rise rate corresponding to different time periods is greater than or equal to the preset difference, the opening of the exhaust gas recirculation valve shall continue to be adjusted.

5. The method according to claim 1, characterized in that, After finally determining that the engine is in the misfire state, the method further includes: The cause of the misfire in the engine is determined, wherein the cause of the misfire includes at least one of the following: ignition system failure, gas supply system failure, abnormal air-fuel ratio failure, and insufficient cylinder pressure failure.

6. The method according to claim 1, characterized in that, Obtain the first engine speed change rate and the voltage change rate of the rear oxygen sensor for the natural gas vehicle, including: The first speed change rate of the engine and the voltage change rate of the rear oxygen sensor of the natural gas vehicle after gear shift are obtained.

7. The method according to claim 1, characterized in that, Before obtaining the first rate of change of engine speed and the rate of change of voltage of the rear oxygen sensor in the natural gas vehicle, the method further includes: The acceleration of the natural gas vehicle is obtained, and it is determined whether the acceleration is greater than an acceleration threshold. If the acceleration is determined to be greater than the acceleration threshold, the natural gas vehicle is determined to be operating under transient acceleration conditions.

8. A natural gas engine misfire detection device, characterized in that, include: The acquisition unit is used to acquire the first speed change rate of the engine and the voltage change rate of the rear oxygen sensor of the natural gas vehicle. The first determining unit is used to determine whether the first speed change rate is greater than the speed change rate threshold, and to determine whether the voltage change rate is greater than the voltage change rate threshold. The second determining unit is used to preliminarily determine that the engine is in a misfire state when the first speed change rate is greater than the speed change rate threshold and the voltage change rate is greater than the voltage change rate threshold, and to adjust the opening of the exhaust gas recirculation valve, and to obtain the second speed change rate of the engine and the voltage rise rate of the rear oxygen sensor during the process of adjusting the opening of the exhaust gas recirculation valve, or to obtain the ignition angle of the engine's knock protection. The third determining unit is used to stop adjusting the opening of the exhaust gas recirculation valve and ultimately determine that the engine is in the misfire state when the second speed change rate is within a preset speed change rate range, the voltage rise rate is greater than the rise rate threshold, and the difference between the voltage rise rates corresponding to different time periods is less than a preset difference, or when the ignition angle of the knock protection changes to the maximum ignition angle.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the natural gas engine misfire detection method according to any one of claims 1 to 7.

10. An electronic device, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing the natural gas engine misfire detection method according to any one of claims 1 to 7.

Images