发动机总成悬置系统解耦方法研究

STUDY ON DEEOUPLED ENGINE MOUNTING SYSTEM

目前汽车发动机动力总成悬置系统设计的主要任务是选择悬置元件的刚度、位置和角度,使悬置系统自由振动模态频率避开发动机怠速激励力频率与车身自振频率,并尽量提高各模态振型的解耦程度,从而提高悬置系统隔振效果.悬置系统按预定频率严格解耦设计是使设计出的悬置系统模态频率完全等于按汽车设计频率规划预定的频率,并使各模态的振型严格解耦,即各向振动能量的解耦度等于1.本文从悬置系统的自由振动方程出发给出了对悬置系统按预定频率严格解耦设计的方程组,可以利用广义逆矩阵的理论求该方程组的解,亦可通过方程组构造函数进而求出该方程组的解,从而提供比当前的悬置系统模态优化设计更为简便高效的优化设计方法.相应的算例验证了本文提出的按预定频率严格解耦设计方程和求解方法的正确性.

At present, the main task of designing a mounting system of automotive engine powertrain is to select appropriate stiffness, position and angle of mounting components so that free - vibration modal frequency of the mounting system can avert from the exciting - force frequency at the idle speed of the engine and the natural fre- quency of vibration of the vehicle body and that the decoupling degree of each mode shape is increased as far as possible, so as to improve the vibration - isolation effect of the mounting system. The design of a mounting system based on strict decoupling at predetermined frequencies is to make the modal frequencies of the designed mount- ing system completely equal to the frequencies predetermined in accordance with the frequency planning of auto- motive design, and to enable strict decoupling of each mode shape of each mode, i. e. , the decoupling degree of vibration energy in every direction equals to 1. Based on a free -vibration equation for a mounting system, this paper presents an equation system for designing a mounting system with strict decoupling at predetermined fre- quencies, provides a solving method for this equation system by using the theory of generalized inverse matrix or method of constructing function, so as to provide an optimal design method more efficient and simpler than the current modal optimization method of mounting system. Relevant example has validated the correctness of equa- tions and solving method of the strict - decoupling design at predetermined frequencies.