Manipulating Frictional Performance of Wet Clutch Engagement through Material Properties and Operating Conditions

Abstract

Wet clutch engagement is mainly influenced by the frictional behaviors between the friction pad and steel plate as well as the lubrication behaviors. A positive μ–V friction coefficient of the wet clutch pad is the most preferable characteristic for improving antishudder behavior. In this study, a wet clutch engagement mechanism is theoretically divided into two major frictional behaviors, namely, direct asperity contact of interacting surfaces and hydrodynamic lubrication, for positive μ–V friction performance. These two behaviors are investigated with regard to both material characteristics of the friction pad–steel plate interactions and hydrodynamic lubrication mechanism. Frictional interactions of the friction pad are analyzed according to the material properties of the friction pad, such as elasticity, permeability, and roughness. Hydrodynamic lubrication, by which the initial period of the engagement is dominantly governed by the waviness of surface shape, is investigated to increase the frictional resistance in the initial stage of engagement relative to that in the final stage of engagement for realizing a positive μ–V friction coefficient. Computational simulations of wet clutch engagement behaviors are performed and compared with each other to obtain positive μ–V friction characteristics of the friction pad.

Keywords

• wet clutch engagement
• hydrodynamic lubrication
• permeability
• waviness
• positive <i>μ–V</i> friction coefficient
• elasticity