| During the operation of agricultural machinery,the output power of the diesel engine affects the performance of the whole machine,gear selection,fault diagnosis,and emission analysis.It is not easy to install a dynamometer or torque strain gauges on the power output of the diesel engine of the agricultural machine.It is not easy to install a cylinder pressure sensor for the diesel engine without a glow plug.Therefore,there are certain difficulties in measuring the power of the diesel engine of agricultural machinery.This paper studies three methods of diesel engine online measurement,and compares the advantages and disadvantages of the three methods and their adaptability to the online measurement system.The results show that the regression analysis method is most suitable for power measurement of agricultural machinery diesel engines.Finally,a set of power online measurement system was designed using sensors,data acquisition card and LabVIEW software,and the whole machine test was carried out based on M1204-D tractor.The content of this article is as follows:(1)The steady-state and transient bench tests were carried out on the diesel engine mounted on the M1204-D tractor,and the universal characteristic data and transient data of the key parameters of the diesel engine were obtained.The relationship between diesel engine power and effective thermal efficiency,speed,intake air flow,fuel injection and excess air coefficient is analyzed.(2)Three diesel engine power measurement methods,GT-Power simulation calculation,neural network and regression analysis,are studied.Using the diesel engine structural parameters and bench test data,a GT-POWER simulation model is established.The calculation results show that the GT-POWER simulation method has high accuracy in calculating the power of the diesel engine,but it is not easy to achieve online power;using the bench test data to convert the speed of the diesel engine,The intake air flow,excess air coefficient and effective thermal efficiency are used as the input of the BP neural network,and the power is used as the output.The BP neural network model is established.The results show that the output power after training is highly fitted to the actual value regression,but the calculation process of the neural network It is purely mathematical calculation and cannot express the internal relationship of the diesel engine parameters;using the bench test data,a regression model between the effective thermal efficiency of the diesel engine and the speed,intake air flow,and excess air coefficient is established,and the regression model is optimized.The results show that the relative error of the prediction results of steady-state conditions is within5%,and the relative error of the prediction results of transient conditions is within 15%.(3)The advantages and disadvantages of the three methods are compared.The results show that the regression analysis method has a specific fitting formula,good adaptability combined with virtual instrument technology,low measurement cost and high accuracy,and is most suitable for online measurement of agricultural diesel engine power.A sensor was installed on the diesel engine of the M1204-D tractor,and a set of on-line diesel power measurement system was built using the data acquisition card and LabVIEW software.The test of the whole machine shows that the system is stable and can measure the power of the diesel engine online.The results of this paper have a strong guiding significance for the online measurement of agricultural tractor power. |
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