A NOVEL TECHNIQUE FOR FREQUENCY AND TIME OPTIMIZATION OF AUTOMOTIVE ENGINE MOUNT PARAMETERS

摘要

In this paper, we examine a linear one degree of freedom engine mount to obtain optimum mount parameters in a passive configuration. An engine mount is a device that may be used to isolate vehicle body from the engine vibrations -forced excitation, while minimizing the effects of road-induced disturbances on the engine - base excitation. The linearity of the system allows us to analyze the frequency and time response characteristics in both excitation cases analytically. Optimal damping and stiffness values for the isolator are obtained by minimizing certain cost functions in the frequency and time domains, respectively. In the frequency domain the cost function is based on the root mean square (RMS) of the absolute acceleration and relative displacement in the frequency domain, and in the time domain it is based on the transmitted acceleration and displacement. The time and frequency responses of the isolator are optimized by varying the stiffness and damping ratios for both base and forced excitation cases. These optimal values are obtained, and the results are verified numerically. In this case, although the mathematical model is linear, it is interesting to note that the time and frequency optimal values are not the same. As a result, this exercise shows that no passive-mount is adequate to perfectly deal with all application specs and isolation criteria. In this paper, a novel approach is suggested to select the mount parameters for various passive or active configurations.