Development of Low Friction Axial-type Lip Seals 2019-01-0182
Reducing torque of a crankshaft seal for a light vehicle is required for the purpose of improving fuel efficiency. A sprung radial fluoro rubber lip is one of the representative seal type for the application. Whereas, an axial silicone rubber lip type oil seal is widely applied to a diesel engine of buses and trucks. This type of oil seal has low torque performance because the main lip load is low. In terms of reliability, it is durable against intervening contamination between lip and slinger while shaft rotating and has long life time. To make low friction and high reliability compatible, applying the axial lip type oil seal to a gasoline engine of light vehicles has been conducted. The seal member of developed seal is changed to fluoro rubber to improve heat durability and product life. A conventional slinger has four helical grooves to enhance pumping function at the sliding area of lip. The developed slinger has a shallow and narrow helical groove that prevents from static leak from a gap of the lip and slinger. The number of groove is increased to improve the sealing performance. A slight oil leak was observed with the conventional seal at high shaft speed. To clarify the phenomenon, direct observation of the leakage and evaluation of lip followability were conducted. The leakage is improved based on the studies. The improvement is described as the gap of lip and slinger at the actual shaft speed. The torque is 60% lower than a conventional radial lip type seal. The rotatory test proves that the seal can be applied to the range of a gasoline engine shaft speed without leakage. The axial rubber lip type oil seal which is applicable to a light vehicle engine has been developed, featuring low friction and high reliability.
Masahiko Inoue, Yuta Kasai, Fangman Xu, Kokichi Hamamoto