Viscous coupling by-pass element for a torque converter and improved bushing design

摘要

A viscous coupling (11) is provided for use as a by-pass element in a torque converter (T). The coupling includes a body member (13) having a body hub portion (25) and a cover member (15) having a cover hub portion (35). The body and cover hub portions are journalled on the outer surfaces (53,57) of a clutch hub portion (41) by means of a pair of identical bushing (59). Each bushing defines on its outer surface a fluid passage (79) including a restricted flow orifice (81). The restricted orifice results in a substantial pressure drop from a high pressure chamber (73) to a seal chamber (70). The cover hub portion (35) defines a counterbore (85) which communicates with the fluid passage (79) to by- pass the restricted orifice (81), such that the seal chamber (70) is maintained at substantially the pressure of a downstream, low pressure chamber (71).