Development for Polymer Overlay Bearing Material for Recent Automotive Engine

The number of vehicles with engines using idling stop systems and hybrid systems to improve fuel consumption has recently been increasing. With idling stop systems the engine is switched off when waiting at city traffic lights or stopping on the road, suppressing the fuel usage which leads to improved fuel consumption. However, with such systems the frequent starts and stops of the engine, where the oil film between the bearings and shaft is squeezed out and direct contact between the components is more likely to occur, can result in increased wear of the engine bearings. As a countermeasure, recent engine bearings can have thin coatings based on polymeric resin material (polymer overlays) applied to the bearing surface, which are known to have good bearing properties such as wear resistance and low friction characteristics. In addition to the use of idling stop systems, certain automotive engines are also designed with increasingly high power output, which of course increases the applied load on the engine bearings, and therefore bearing materials that can withstand such high loads are required.