Development Of Indicator Diagram Measurement System For Marine Diesel Engine

Indicator diagram of cylinder pressure is the basic method to describe the dynamic performance of diesel engine.It's the basis for internal combustion engine's performance parameter calculation and heat release rate analysis,and It's also the evaluation standard for the accuracy of simulation calculate of internal combustion engine's combustion process.So measuring the indicator diagram accurately plays an important role.In view of this,in this paper we developed a indicator diagram measurement system for marine diesel engine.It is consisted of sensor,signal conditioning circuit,single chip computer data acquiring system,host computer and testing software.The following contents were mainly researched.(1) According to the request of external trigger signal for single chip computer data acquiring system and the request of indicator diagram,We designed a signal conditioning and frequency multiple circuit for different type of signal.And also we designed a signal isolation circuit.(2) We designed the data acquiring system base on single chip computer system to sample the cylinder pressure of diesel engine.And the collected data were transmitted to the host computer or usb disk by serial communication.(3) Using virtual instrument technology and Lab VIEW graphical programming language,compiled the indicator diagram measurement system program which can do the post-processing and analyzing to the collected signals,then according the measured indicator diagram we can compute out the engines performance parameters. Such as mean indicated pressure,indicated power,explosion pressure and the corresponding crank angle,ratio of pressure rise and so on.(4) The measure system we developed was tested on the type of 8L21/31 diesel engine,verified the function and precision of the system.This developed system has the characteristics of data acquisition accurately,steady performance,strong anti-interference ability and so on.It provides a measurement technical means for monitoring the diesel engine's performance.