Development of Exhaust Mount Which Applied Low Damping Liquid Silicone Rubber 2018-01-0156
The use of silicone rubber as anti-vibration rubber in automobile exhaust systems is known to be an effective general countermeasure to heat damage. However, there are limits on the use of silicone rubber because its vibration transmission characteristics are not as good as those of EPDM a rubber material commonly used in exhaust mounts. In this research, a new silicone rubber material with better vibration transmission characteristics, low damping, than EPDM was developed using liquid silicone rubber. Ordinarily, a technique that reduces the damping components of rubber is used to provide low-damping to anti-vibration rubber materials like EPDM. Such damping components include reinforcing agents like carbon black and silica, which are injected to reinforce the rubber. Damping in polymer is the result of internal friction when rubber deforms, so damping is controlled by using material with few side chains. Damping in filler is the result of deformation of the aggregates that form, so damping is controlled by using a grade of materials with large particles and small, secondary aggregate structures. Until now, there have been limits on how much one could lower damping by using these conventional techniques with silicone rubber. Among other reasons, there are few variations on dry silica, which needs to be used in the reinforcing agent. Thus, this research used liquid silicone rubber and successfully controlled the friction between polymers, providing low damping by achieving a high-density crosslinking structure. Analysis confirmed that components made with this material offered better vibration transmission characteristics when compared to EPDM components with the same shape and static spring value. The research also took advantage of the fact that silicone rubber’s spring properties have little dependence on temperature, thus simultaneously enhancing vibration transmission characteristics in the low temperature range.