Content area
Full text
1 Introduction
A hydro-viscous drive is based on Newton's Law of Viscosity and transmits power by the shearing force of oil film between friction discs. It is similar in structure to a wet clutch, but different from each other in friction material, friction disc surface grooves and working oil passage, etc. A hydro-viscous drive can be used both for speed regulating and for speed-regulating start. Speed regulating means controlling the speed of fan or water pump, speed-regulating start means controlling the startup process of such machinery as a belt conveyor.
A speed-regulating start means that a startup process can be finished within a given time according to a given starting curve. It aims at reducing the dynamic stresses and prolonging the service life of the machinery. Up to the present, many studies on mechanism of hydro-viscous drive and its application in speed regulating have been carried out.
Dong and Zhou revised the steady-state Reynolds equation by incorporating the fluid rotational inertia force in the calculation model and studied the transmission mechanism of the modulated clutch numerically, obtained the temperature and hydrodynamic pressure distribution of the oil film between friction discs ([1] Dong and Zhou, 1991).
Razzaque and kato numerically solved a steady-state Reynolds equation with inertia consideration to simulate the viscous torque, flow rate, and axial force of an oil film between a grooved separator friction plate pair of a wet clutch at a disengaged state, in which straight grooves with rounded, trapezoidal, and V-section at different angular orientations were considered and the effects of their geometry and orientation presented ([2] Razzaque and Kato, 1999).
Jen and Nemecek conducted a combined theoretical and experimental analysis on the temperature rise of the oil flow between the plates of a wet clutch during an extended slip engagement ([3] Jen and Nemecek, 2000).
With consideration of oil-film inertia and heat effects, by using mean energy equation and heat conduction equation, [4] Hong et al. (2003) established the thermal analysis model to investigate the behavior of frictional discs in speeding wet clutch, in which the power-law fluid model, Patir-Cheng average flow model and GT asperity contact model were adopted ([4] Hong et al. , 2003).
[5] Aphale et al. (2006) developed a 2D and 3D mathematical model, respectively,...