Hydraulic mount with low amplitude, low-to-medium frequency vibration

Abstract

A hydraulic mount assembly includes a pair of mounting members connected together through a hollow elastomeric body. This hollow body is closed by a resilient diaphragm so as to form a cavity for a damping liquid. A partition divides the cavity into a primary chamber formed between the partition and the hollow body and a secondary chamber formed between the partition and the diaphragm. The partition also includes a primary (damping) track and a secondary (dynamic rate reducing) track providing fluid communication between the chambers. A decoupler is held for limited reciprocating movement in an annular groove in the secondary track. In operation, high amplitude vibratory inputs seat the decoupler forcing damping fluid to flow between the primary and secondary chambers through the damping track. The resulting high level of damping and high dynamic rate serve to suppress the vibrations and control engine movement/noise. In response to low amplitude and particularly low-to-medium frequency vibratory inputs, the decoupler remains unseated, allowing damping fluid to flow around the decoupler and through the secondary track. The resulting fluid inertial forces create a low dynamic rate and a soft mount for better vibration and noise isolation. At high frequency and low amplitude, such as during normal idle, the decoupler reciprocates normally, thus avoiding damping action.