Clutch Wet

Abstract

A wet clutch, which is a type of an oil‐lubricated friction device, is widely utilized in contemporary drivetrain systems as a torque‐transmission or torque‐holding device. It is most commonly employed in a planetary gear‐based automatic transmission as a means to alter torque paths for automated gear ratio changing. A wet clutch is also found as a vehicle launch device in a lay shaft automatic transmission, as a torque split device in a torque transfer case, and, most recently, as a torque‐coupling device in a gasoline‐electric hybrid drive. Although the wet clutch technology has been around over 100 years, its design continues to evolve even today to meet ever‐demanding challenges in fuel economy improvement, drivability enhancement, and shift quality refinement. This chapter describes a wet clutch structure, components, construction materials, and key geometric features. The operating mechanisms and characteristics are presented in details for open clutch, engagement, and release processes. A clutch design process and evaluation methods are discussed in relation to fuel economy, automatic shift quality, and durability requirements. This chapter is concluded with a summary of future trends in wet clutch technologies.