The Research On Power Test In Real Time For Engine Of Yanmar Combine Harvester

The dynamic: performance of engine is one of important indexes of engine technical status. It can reflect engine technical status, and the further test can be done according to it. Engine test-bed experiment is the traditional main means of testing the performance of engines, which need the engine fixed on the test-bed. One of the shortcomings of it is inconvenient, and the other is the work status after being loaded when the engine is tested is different from what it is at actual work status. It cannot test the performance of engines in real time. Now the common means of testing the performance of engines in real time is noload dynamometer test, which computes the engine power by measuring the average accelerate time. The accuracy and repetition of it is low, and it cannot be loaded acfcording to the status. So it has obvious limitation. The power testing system in real time applied to Yanmar combine harvester with industrial control computer is studied in this paper on the basis of former achievements.In the system, the rotate speed sensor and torque sensor are fixed between the engine power output shaft of Yanmar combine harvester and the power input shaft of working device. The signals of torque and rotate speed are preprocessed such as V/F, amplified. And the power is computed. The bug, that data-acquisition card's timer/counter is not accurate, is made up by adding Single Chip Micyoco. And the system's precision is improved.Meanwhile, the working condition of Yanmar combine harvester is very foul, so the system is prone to be disturbed. Interference-free measures are taken on hardware such as optoelectric coupling, earth, screen and filtering. And measures on software such as watch dog circuit and digital filter were taken too. These measures ensure the system work normally, and ensure the result steady and accurate.An engine power testing software for Yanmar combine harvester based on Visual Basic 6.0 is developed. The software applies the technology of dynamic multipledocuments. It includes password module, initialization module, waves of torque and rotate speed display module, data and report forms module and help module. It can display the waves and value of torque and rotate speed at the same time, and the data can be saved in database as the reference information for status inspecting and malfunction diagnosis in the future.After the system is designed, frequency generator is used to test the precision of system. Through the experiments, it can be concluded that the precision of system is very high, and it can fit the actual requirement, and be of very valuable.At last, this paper also illustrates the shortage and some parts needed to add in of the system, and give some suggestion for the study on this topic in the future.