| Automobile, as a means of transport, on the one hand has brought great convenience to the people's lives and production, on the other hand, has brought environmental pollution and energy shortage. Our country prohibit the high fuel consumption vehicles which don't achieve the national standards from being drived, and the fuel economy of vehicles is payed extensive attention by increasing number of people. So it is greatly significant to detect the fuel consumption of the vehicles.The evaluation of vehicle fuel economy is generally determined through tests of engine fuel consumption measurment. However, with the electronic control gasoline engine widely used, it brings lots of problems to engine fuel consumption measurment. Traditional methods such as measuring the volume and weight of fuel consumption can't work when EGI engine returns oils by a great amounts and supplies oil in a high pressure as well as when oil pipes bear different pressure and temperatures. And also application of special consumption instrument will increase cost., affect normal oil supply due to necessary conversion of oil way, and cause potential security problems. Therefore, in order to meet the actual needs of the EFI gasoline engine fuel consumption measurement, it is an inevitable step to develop a set of rapid, accurate measurement syetem of engine fuel consumption.This thsis puts forword and introduces a brand new way to measure EFI gasoline engine fuel consumption in accordance to completely different principles from the traditional ones through analyzing the issue of vehicle fuel consumption at home and abroad, work characteristics and working principle of EFI gasoline engine which is different from the traditional gasoline engine carburetor. Based on this approach, develop a convenient, fast and accurate vehicle fuel consumption test system which can detect fuel consumption when it needn't to disassemble oil circuit of examined vehicles. This method not only playes a role in carrying out the fuel consumption detection in a comprehensive performance testing of the vehicle, but also provides a foundation for developping the rapid fuel detection devices of vehicle fuel consumption measurement.The thesis mainly accomplished the work below: (1) After reviewing a large number of relevant documents, an overview for the development of measurement methods of vehicle fuel consumption at home and abroad was summarized. Based on deeply analysing the work process and the principle of EFI system, the fuel consumption test methods which determined the fuel consumption of vehicle through extracting pulse signal from ECU which controls the electromagnetic fuel injector was puted forward.(2) Stated the functional requirements, the working principle and the internal control circuit of .the fuel consumption measurement system. Mainly designed and selected its hardware and software, the part of hardware mainly included the LM324 chip and AT89C51 single-chip. Then carried out a detailed analysis of the internal structure and pin of AT89C51 single-chip. The software worked with the control hardware circuit to complete the fuel consumption detection rapidly and its function was implemented through the sub-module. In addition, introduced the main program, initialization module, the control panel management modules and fuel consumption test modules.(3) In order to verify the feasibility of fuel consumption measurement system, EFI gasoline engine fuel consumption measurement study was carried out. Taking into account the existing conditions of the laboratory, in accordance with the test data need to be tested, a test platform was set up. In this paper, the test platform was related to the engine, fuel consumption test bench systems, engine and fuel injector connected measurement system, as well as the engine and dynamometer system auxiliary connection. In order to check the reliability of system's software and hardware and the stability of signals, LAUNCH X-431 decoder and the United States oscilloscope FLUKE 98 II was added to the test platform.(4) Carryed though the fuel consumption measurement test of the EFI gasoline engine in the test platform. Due to the finite laboratory conditions and time, fuel consumption tests were only carryed out in the idle state conditions and well-proportioned speed. The engine speed, fuel injection time, the test time and the number of fuel injection can be extracted in the course of the trial of the fuel consumption measurement system during the test time. It was concluded that the fuel consumption calculated and the fuel consumption measured are all clearly linear at different courses of the experiment through experimental data analysis and processing. the regression equations between the two ones by using least squares curve fitting method. Error analysis showed that it was not related with the engine speed and torque, which verified the fuel consumption measurement system was feasibled and had high accuracy. (5) Because the test system used the single-chip and realized the intelligent test, the error must be also limited within the scope of control, but it can not completely eliminate the error. Finally, sumed up the fuel consumption test system errors that may exist, and error correction methods and the methods of avoiding errors were brought forward on this basis. Test showed that the process of the fuel consumption measurement is simple, safe and convenient and the obtained results are timely and accurate because single-chip control system replaces the traditional mechanical measurement system. The measurement system has low cost, so its practical applications will be facilitate and accepted by people. It plays an important role in evaluating fuel consumption of vehicle.In this thsis, EFI gasoline engine oil consumption measurement test can be also researched from other aspects. The next step can follow below: on the one hand, carry out pilot studies when the engine is in the conditions of warm-up, idling, acceleratiing and works in a variety of conditions such as different intake air temperatures, different environmental temperatures, different fuel pressure, different inlet pressure, different battery voltage and so on. Analyze how they influence the fuel consumption when the system is working and further analyze the error. This can reduce the disparity betwwen the detection volume and the actual fuel injection amount, and further enhance the accuracy of measurement systems. On the other hand, take test on other models of electronically controlled gasoline engine by using the fuel consumption measurement system in oder to further validate its feasibility and analyse as well as amend the impact of factors, so the test can depart from the indoor test platform as soon as possible. |
PDF Full Text Request