Research On Starting Noise Reduction Of Fuel Automobiles

With the rapid development of automobile industry, car owners is growing rapidly. Automobile noise pollution has become a problem which people increasingly concerned about. Although automobile noise has been studied by scholars increasingly, there is little research on the noise of the car when it is starting. As a result of directly applying voltage on engine during startup, flywheels and drive gears rub and screech. A whistling sound will generate. The noise interferes with people’s life, even influences people’s health. By measurement, the noise generated in the process of car starting which is about 90dB (similar to the sound size of car horns) is 31 times louder than the noise after starting which is only 60dB (similar to the sound size of normal conversation).Through designing soft starting for automobiles, engine speed will smoothly be increased and the noise will be reduced, the thesis analyses from three aspects and makes the most reasonable design. Meanwhile, the main content is listed as follows:Firstly, the noise of automobile during startup is measured. The source of noise is analyzed through the classification of the noise in starting system and the basic structure and working principle of the fuel vehicle starting system.Secondly, the minimum starting speed and starting torque required in the starting process are calculated through the relevant parameters of automotive starter and engine fuel. The thesis takes QD124 starter as an example and figures out its minimum starting voltage.Thirdly, the noise reduction measurement of soft starting based on PWM technology is put forward. Through the buck soft start experiment, the feasibility of this scheme is verified. Parameters of several common DC-DC converters are calculated. The advantages and defects of each converter are compared by simulation results. Then soft start scheme based on Cuk converter is selected. The voltage and current double closed loop control circuit is designed by modeling Cuk converter.Finally, Soft start control system based on DSP is designed and software control program based on DSP is compiled. A real time simulation platform for soft start system based on Cuk converter is built. Hardware and software architecture of dSPACE real time simulation system is configured. The correctness of the control system is verified through dSPACE real time simulation platform.In this thesis, the soft start of engine is realized by simulation. from starting speed steadily rising to the rated speed.Noise during startup is effectively reduced and high starting current is limited.