Research On Online Monitoring And Application Technology Of Diesel Engine Cylinder Pressure

In the field of ship propulsion,diesel engines are the main power source for ships,and their working conditions and performance directly affect the power,environmental protection,and safety of ship navigation.The lack of real-time monitoring of the working condition and performance of diesel engines during actual operation can lead to the inability of personnel to adjust operating conditions and parameters in a timely manner,resulting in increased fuel consumption,increased emissions,and other problems that affect the economic benefits and environmental protection of ships.On the other hand,it can also lead to personnel being unable to detect diesel engine problems and faults in a timely manner,resulting in increased damage and maintenance costs,which affect the power and safety performance of ships.The cylinder pressure signal can reflect the thermal process inside the diesel engine.By online acquisition and analysis of cylinder pressure signals,the working performance of the diesel engine and the combustion state inside the cylinder can be accurately monitored.Therefore,carrying out research on online monitoring and application technology of diesel engine cylinder pressure has important significance and engineering value for diesel engine status monitoring and performance improvement.Based on the principle of cylinder pressure monitoring and application technology,this paper designs and develops a diesel engine cylinder pressure online monitoring system,which can achieve compression top dead center adaptive calibration,real-time display of indicator diagrams,online combustion analysis,and monitoring of characteristic parameters of the working process inside the cylinder.Firstly,the overall design scheme of the monitoring system is determined from two aspects: technical indicators and overall framework,and the monitoring system is designed from the hardware and software aspects.The hardware design part includes the hardware architecture and composition of the system;the software design part first carries out the overall design from four aspects: environment configuration,functional requirements,implementation methods,and hierarchical architecture,and then designs each functional module,user interface,and usage method based on the Lab VIEW2018 platform.Then,the calibration and conditioning of various signals in the monitoring system are carried out.Based on the Schmidt trigger,the Z signal and A signal of the photoelectric encoder are conditioned,and the compression top dead center is calibrated through the photoelectric encoder,and the single cycle indicator diagram is obtained based on the array circular shift method.The calibration of the cylinder pressure sensor and the calculation of the cylinder pressure signal gain are performed,and the cylinder pressure signal is conditioned based on the frequency domain filtering method.Finally,based on the LRC4108C53 diesel engine,a cylinder pressure online monitoring test bench was established,and the adaptive calibration test of the compression top dead center and the functional verification test of the monitoring system under multiple operating conditions were designed and completed.The results show that the system can meet the purpose of online acquisition of cylinder pressure,real-time analysis of working conditions and performance.During the operation of the ship,personnel can adjust the operating conditions and parameters of the diesel engine based on the data feedback of the cylinder pressure online monitoring system,discover problems and faults in a timely manner,and ensure the safe and healthy operation of the ship.