Hybrid Hydraulic Engine Mounts

Abstract

The engine mounting system connects the engine to the vehicle structure. It supports the engine weight, ensures its position in the car chassis, and provides vibration isolation to the cabin. Hydraulic engine mounts are used due to their ability to further improve noise and vibration isolation and their varying stiffness and damping characteristics with amplitudes. Low engine amplitudes require low stiffness to reduce the transmitted vibration. While for significant excitation, it is desirable to have higher stiffness to limit the engine motion in the vehicle structure. Decouplers are added to the conventional hydraulic mounts to provide dual stiffness characteristics. However, decouplers can be unreliable due to their ability to rotate and stick to the mount bounds, thus destroying it. This thesis presents passive hydraulic engine mount alternative designs focusing on nonlinear and bilinear spring elements. The springs are added to replace the decoupler to add the amplitude sensitivity characteristics to the mount. The proposed engine mount design was mathematically modeled, and MATLAB simulations were carried out to simulate the engine mount's dynamic stiffness and perform parametric studies to ensure the piston motion and chamber pressures are reliable. Moreover, the nonlinear spring realization stage was done using the ANSYS Mechanical APDL program, and a conclusion was driven to choose the most reliable stiffness element type for such an application.

Date of Award	Aug 2023
Original language	American English
Supervisor	Nader Vahdati (Supervisor)