Marine gas engine misfire diagnosis system

Abstract

The utility model relates to a misfire diagnosis system for a marine gas engine, and relates to the technical field of monitoring of marine gas engines, the misfire diagnosis system comprises an engine exhaust header pressure sensor and an engine electronic control unit, the engine exhaust header pressure sensor is arranged on an exhaust pipe of the engine and is used for collecting exhaust pressure waveform data in real time, and the engine electronic control unit is used for monitoring the exhaust pressure waveform data; the engine electronic control unit receives pressure waveform data from the engine exhaust manifold pressure sensor. According to the misfire detection system for the marine fuel engine, the exhaust header pressure wave signal is selected as a signal source, engine misfire monitoring and diagnosis can be carried out, and the requirement for stable operation of the marine engine is met.

Description

Technical Field

[0001] The present invention relates to the technical field of monitoring of marine gas engines, and more particularly to a misfire diagnosis system for marine gas engines. Background Art

[0002] Facing the increasingly strict emission regulations of the International Maritime Organization, marine engines fueled by natural gas have obvious advantages and application prospects in terms of controlling emissions and reducing operating costs. However, due to its narrow operating range, it is prone to knocking and misfire faults during operation. Especially the latter not only affects the power performance of the engine, but also continuous misfires will cause a large amount of harmful gases (such as methane) to be discharged, posing huge safety and environmental protection risks. At present, relatively high-end large marine natural gas engines generally adopt the method of installing product-level cylinder pressure sensors in each cylinder to monitor misfires, which not only has a high cost but also has a certain failure rate due to the high precision requirements of the cylinder pressure sensors and the harsh working environment in the cylinder. Summary of the Invention

[0003] The object of the present invention is to provide a misfire detection system for marine fuel engines, which can monitor and diagnose engine misfires and meet the requirements of stable operation of marine engines.

[0004] To achieve the above object, the technical solution of the present invention provides a misfire diagnosis system for marine gas engines, including an engine exhaust manifold pressure sensor and an engine electronic control unit. The engine exhaust manifold pressure sensor is arranged on the exhaust pipe of the engine and is used to collect exhaust pressure waveform data in real time. The engine electronic control unit receives the pressure waveform data from the engine exhaust manifold pressure sensor.

[0005] Preferably, a calibration and optimization module is also provided for adjusting and optimizing system parameters to improve the accuracy and reliability of misfire monitoring.

[0006] Preferably, the engine electronic control unit processes and analyzes the received pressure waveform data.

[0007] Preferably, the engine electronic control unit can judge whether there is a misfire phenomenon according to the analysis result.

[0008] Preferably, the engine electronic control unit can calculate the misfire integral and take measures according to the misfire integral.

[0009] Preferably, the measures taken include stopping the injection of natural gas into a specific cylinder or limiting the torque.

[0010] The technical solution of the present invention also provides a misfire diagnosis method for marine gas engines, including the following steps:

[0011] Collect the difference between the peak and trough of the engine exhaust pressure wave, which is defined as the characteristic parameter of the exhaust pressure wave during normal engine operation;

[0012] Obtain the characteristic parameters of the time-domain pressure wave corresponding to the exhaust stroke of each cylinder in each working cycle of the engine;

[0013] Compare the characteristic parameters of each cylinder in the working bearing with the characteristic parameters of the exhaust pressure wave during normal engine operation in real time. If the deviation is greater than a certain percentage, it is determined that the cylinder misfires in this working cycle.

[0014] Preferably, if misfire is detected, the misfire integral is accumulated. After reaching a certain threshold, the corresponding fault is reported according to the proportion of the misfire integral.

[0015] Preferably, if the proportion of the misfire integral from a certain cylinder exceeds a certain proportion, a single-cylinder misfire fault is triggered and the cylinder is dynamically cut off.

[0016] Preferably, if the proportion of the misfire integral from a certain cylinder is lower than a certain proportion, a random fault is triggered and the torque is limited.

[0017] In summary, the present invention includes the following beneficial technical effects:

[0018] The present invention provides a misfire detection system for a marine fuel engine. By selecting the exhaust manifold pressure wave signal as the signal source, engine misfire monitoring and diagnosis can be carried out, meeting the stable operation requirements of marine engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the working steps of a misfire diagnosis system for a marine gas engine of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] The thermodynamic parameters in the engine exhaust formation process include information on the cylinder combustion condition, the working conditions of accessories such as spark plugs and exhaust valves. The dynamic characteristics of the exhaust gas flow directly reflect the changes in the boundary conditions of the pipeline system, and thus can reflect the operating state of the engine. For this reason, the present invention provides a misfire detection system for a marine fuel engine. By selecting the exhaust manifold pressure wave signal as the signal source, engine misfire monitoring and diagnosis can be carried out, meeting the stable operation requirements of marine engines.

[0022] The engine misfire diagnosis system includes an engine exhaust manifold pressure sensor and an engine electronic control unit. The engine exhaust manifold pressure sensor is installed on the exhaust pipe of the engine and is used to collect exhaust pressure waveform data in real time. The engine electronic control unit receives the pressure waveform data from the engine exhaust manifold pressure sensor and processes and analyzes it. Based on the analysis results, the engine electronic control unit determines whether there is a misfire and calculates the misfire integral. According to the misfire integral, the engine electronic control unit decides on the measures to be taken, such as stopping the injection of natural gas into a specific cylinder or limiting the torque, etc., to protect the engine.

[0023] The working steps of the engine misfire diagnosis method are as follows:

[0024] Under different loads, the difference between the peak and valley of the engine exhaust pressure wave is collected in open loop and defined as the characteristic parameter of the exhaust pressure wave during normal engine operation;

[0025] For each working cycle of the engine, the characteristic parameters of the time-domain pressure wave corresponding to the exhaust stroke of each cylinder are obtained;

[0026] The characteristic parameters of each cylinder within the working cycle are compared with the characteristic parameters of the exhaust pressure wave during normal engine operation in real time. If the deviation is greater than a certain percentage, it can be determined that there is a misfire in this cylinder within this working cycle;

[0027] If a misfire is detected, the misfire integral is accumulated. After reaching a certain threshold, the corresponding fault is reported according to the proportion of the misfire integral;

[0028] If the proportion of the misfire integral from a certain cylinder exceeds a certain proportion, a single-cylinder misfire fault is triggered and the cylinder is dynamically cut off; if the proportion of the misfire integral from a certain cylinder is lower than a certain proportion, a random misfire fault is triggered and the torque is limited.

[0029] The misfire diagnosis system of the present invention is mainly based on the following principle: During the exhaust stroke of in-cylinder combustion, an obvious pressure peak will be generated at the exhaust pipe position. This peak has good consistency and high repeatability under a fixed load. If a misfire occurs, the peak value generally changes greatly, and this is used to judge whether there is a misfire. At the same time, the exhaust strokes of different cylinders have a fixed cycle in the time domain, so it is relatively reliable to distinguish which cylinder or cylinders the misfire occurs in. The electronic control unit obtains the misfire integral through the number of misfires and the number of cycles in which the misfires occur as the basis for judging the severity of the misfire and distinguishing between single-cylinder misfire and random misfire. Subsequently, the electronic control unit takes different measures for single-cylinder misfire faults and random misfire faults. For single-cylinder misfire faults, the injection of natural gas into this cylinder and ignition are stopped, and for random misfire faults, the torque is limited.

[0030] The fire diagnosis strategy with a similar principle to the present invention is currently applied to the electronic control system of vehicle natural gas engines. However, due to the feedback regulation of the oxygen sensor, if a fire occurs, it usually leads to a change in the gas injection volume, aiming to adjust the air-fuel mixture ratio. Therefore, it may result in a situation where the peak value after a fire is higher than before, interfering with the diagnosis of the fire. However, considering the current situation that closed-loop control is generally not adopted for marine engines, diagnosing the fire using the exhaust pressure waveform will be more accurate. At the same time, marine engines are generally low-speed engines, and the exhaust manifold pressure waveform is less affected by the dense waveforms caused by high speeds, requiring a lower sampling frequency for the exhaust manifold pressure, making it more suitable to adopt a scheme for monitoring and diagnosing the fire based on the exhaust manifold pressure waveform.

[0031] The fire diagnosis system of the present invention has a large calibration and optimization space. Its calibration parameters include but are not limited to: the exhaust waveform characteristic parameters (hereinafter referred to as calculated characteristic parameters) under normal engine operation at different loads, the time domain start and end points of the waveforms corresponding to the exhaust strokes of each cylinder, the deviation threshold between the actual characteristic parameters and the calculated characteristic parameters, the fire integration threshold for fire faults, and the percentage threshold for distinguishing single-cylinder fire faults and random fire faults. By calibrating the above parameters, the accuracy and reliability of the fire monitoring system can be improved.

[0032] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A marine gas engine misfire diagnosis system, characterized in that, It includes an engine exhaust manifold pressure sensor and an engine electronic control unit. The engine exhaust manifold pressure sensor is disposed on the exhaust pipe of the engine and is used to collect exhaust pressure waveform data in real time. The engine electronic control unit receives the pressure waveform data from the engine exhaust manifold pressure sensor. The engine electronic control unit can calculate the misfire integral and take measures according to the misfire integral. A calibration and optimization module is also provided, which is used to adjust and optimize system parameters to improve the accuracy and reliability of misfire monitoring.

2. The marine gas engine misfire diagnosis system according to claim 1, characterized in that, After receiving the pressure waveform data, the engine electronic control unit processes and analyzes it.

3. The marine gas engine misfire diagnosis system according to claim 2, characterized in that, The engine electronic control unit can judge whether there is a misfire phenomenon according to the analysis result.

4. A marine gas engine misfire diagnosis system according to claim 3, characterized in that, The measures taken include stopping the injection of natural gas or limiting the torque to a specific cylinder.

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