增程式电动车悬置系统优化及NVH性能测试

Optimization and NVH Performance Test for Mounting System of Extended Range Electric Vehicle

为了改善增程式电动车的NVH性能,采用四点衬套式悬置系统支撑该电动车的动力总成,同时设计了两种匹配方案.原车状态的设计方案存在较严重的振动耦合现象,经过悬置系统固有频率匹配与振动解耦率的优化以后,主振动的振动解耦率均高于80%,频率分布对于怠速工况的隔振有利.本文对优化设计的悬置系统进行了NVH性能测试,结果表明:四个悬置在三个方向的怠速工况隔振量都在20dB以上.怠速工况下,方向盘的振动加速度均小于0.05 g,半阶次无明显振动;当发动机转速为3 000r/min时,方向盘处一阶主振动较小,振动加速度只有0.02 g,而半阶次振动加速度非常大,最大振动加速度达到0.15 g.该研究工作表明,半阶次振动是中高转速下增程式电动车振动和噪声产生的主要原因.

In order to improve the NVH performance of extended range electric vehicle, four-points ＇ bush mounting system was adopted to support its powertrain system. Two matching schemes for the a- bove mounting system were designed. The original designed scheme had the severe vibration coupling. Vibration decoupling ratios of the main vibration directions were all higher than 80 %, and frequency dis- tribution was favorable for the vibration isolation of idle mode after the natural frequency match and vi- bration deeoupling ratios optimization of the mounting system. NVH performance tests were carried on for the mounting system of optimal design, and test results had shown that the vibration isolation for the four mounting systems in the three direction of the idle mode was more than 20 dB. In idle mode, the vi- bration acceleration of the steering wheel was less than 0. 05g, and obvious half order vibration didn＇t exist. When the engine＇s speed reached 3 000 rpm, the one order main vibration of the steering wheel was smaller than any other order vibration, and the vibration acceleration was only 0. 02g, but half or- der vibration acceleration was very large, and their maximum acceleration reached 0. 15g. The researchwork had shown that lhe main reason of the vibration was half order vibration at middle and high speed.