Based On No-load To The Dynamometer And Speed Fluctuation Of The Engine Fault Diagnosis System

As the developing of the Internal Combustion Engine, its basic structure has been fixed. But the implement of the function of different parts has been being rapidly improved, and the technology applied has a trend of more electrization, more complication and diversification. This trend brings considerable trouble in maintenance, and even sometimes the unnecessary waste of labor. For example, if the nozzle of the last cylinder was ruined, we must check the nozzle one by one and finally find it. This design is just make it possible that we could find out the cylinder that has problem with out taking the engine apart, and thus the waste of labor and money can be saved.In this design, the data collection must be rapid and should be handled in batch, so the choosing of MCU is important. The ATmega8 is a low-power CMOS 8-bit micro controller based on the AVR RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega8 achieves throughputs approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed. The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The ATmega8 provides the following features: 8K bytes of In-System Programmable Flash, IK bytes of SRAM, On-line Programmable and so on. The features upwards make the ATmega8 competent to the request of the design.The author mainly concerns on the research and the development of the no-load power measuring system based on ATmega8, which can conveniently measure the power of engine. Speed is measured in real time and is analyzed by using the least square method in this system, the n-t curve is fitted, so the testing error will be minimized. The experiment shows that this system can realize the power measuring with convenience and quickness, and the results are reliable. If the differences in power between cylinders are small, it shows that the engine is working finely, or we should use the rev fluctuation characteristic to analysis. Through the measurement of the rotation speed of the crankshaft and using the interactive analysis method, the cylinder that is working abnormally can be fixed, and then to repair, which could reach a level of optimize, quickness and simpleness.Because of the limited knowledge of the author, the oversight and some mistakes can not be avoided, you are welcomed to point them out so that they can be corrected.