Dynamic transmission characteristics during soft-start of hydro-viscous drive considering fluid-inertia item

Abstract

Considering the influence of the fluid-inertia item on dynamic transmission characteristics during soft-start of hydro-viscous drive (HVD), theoretical models were derived with the aim of revealing the effect of engagement pressure, lubricant viscosity, viscosity-temperature characteristics, surface roughness and the ratio of inner and outer radius of plates on total torque and viscous torque. The results indicate that the increase of engagement pressure and lubricant viscosity shortens soft-start time and increases peak total torque in the stage of mixed lubrication. The decrease of surface roughness and effective contact area of plates can both shorten soft-start time. And yet two cases of time to reach peak total torque are in different stages. Fluid-inertia item included can help to avoid fluctuation of the total torque while increasing lubricant viscosity or reducing surface roughness. It can increase soft-start time obviously when considering viscosity-temperature characteristics. In short, the research reveals the influence rules of the fluid-inertia item on dynamic transmission characteristics of HVD; additionally, fluid-inertia item included contributes to reduce oscillation of the total torque and the decline in efficiency. Therefore, the research results lay a theoretical foundation for the design of high-power HVD device.