Development of High Damping Powertrain Mount Using Thixotropic Fluid

Vibration isolation performance and damping performance of the powertrain mount are important for enhancing the noise and vibration performance and the ride comfort performance of a vehicle. In the present research, attention was focused on how the ideal viscosity differs with the input frequency according to the principle of damping that occurs in hydraulic mounts. By combining the liquid column resonance phenomenon with thixotropic fluid, a technology was developed for achieving a high-level balance between low dynamic spring and high damping, which are trade-off elements in a hydraulic mount. An aqueous solution of glycol used as the base fluid was combined with clay mineral as a thixotropic agent. From the results of the viscosity measurement, it was found that as the amount of thixotropic agent added increased, the viscosity gradient increased with respect to the shear rate, but at the same time, the overall viscosity also increased. In terms of the viscosity gradient and high shear region viscosity, the optimal concentration of clay mineral in the thixotropic fluid was indicated. The dynamic characteristics of mount components with this thixotropic fluid sealed inside them were tested. The results indicate that the damping coefficient increased by 15% while the dynamic spring constant was maintained. The mount with thixotropic fluid sealed inside it was attached in an actual vehicle and bench testing was carried out. The result showed that the vibration transmission characteristics at powertrain resonance point were improved by 1.3 dB due to the high damping performance of the mount. By using this technology, a balance between low dynamic spring and high damping of the mount was successfully achieved simply by changing the sealed-in liquid.