Influences of the Contact State between Friction Pairs on the Thermodynamic Characteristics of a Multi-Disc Clutch

Abstract

The relationship between clutch thermodynamic characteristics and contact states of friction components is explored numerically and experimentally. The clutch thermodynamic numerical model is developed with consideration of the contact state and oil film between friction pairs. The clutch bench test is conducted to verify the variation of the clutch thermodynamic characteristics from the uniform contact (UCS) to the intermittent contact (ICS). The results show that the oil film decreases gradually with increasing temperature; the lubrication state finally changes from hydrodynamic lubrication to dry friction, where the friction coefficient shows an increasing trend before a decrease. Thus, the friction torque in UCS gradually increases after the applied pressure stabilizes. When the contact state changes to ICS, the contact pressure increases suddenly and the oil film decreases rapidly in the local contact area, bringing about a sharp increase in friction torque; subsequently, the circumferential and radial temperature differences of friction components expand dramatically. However, if the contact zone is already in the dry friction state, friction torque declines directly, resulting in clutch failure. The conclusions can potentially be used for online monitoring and fault diagnosis of the clutch.

A New Multi-Physics Coupled Method for the Temperature Field of Dry Clutch Assembly

“…Moreover, the thermal deformation is greatly increased at high temperatures, which results in more friction heat being generated. Consequently, the sliding friction, friction-generated heat, thermal deformation, and uneven contact of the dry clutch assembly are tightly coupled [5,6]. Since the coupling mechanism and the temperature field of the clutch are crucial for clutch design and reliability analysis, a large amount of research has paid attention to the temperature field of the clutch.…”