The hydro-viscous drive (HVD) has been widely used in fan transmission in vehicles, fans, and scraper conveyors for step-less speed regulation or soft starting. In the mixed friction stage, the contact, friction, and torque characteristics of friction pairs are very complex and change at any time. The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage. The fuid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory. In addition, the contact friction coefcient of the friction pairs was taken into consideration and measured by using the MM1000-III friction and wear testing machine. The asperity friction torque and total torque in the mixed friction stage were obtained and fnally, the test rig for the torque characteristics was set up. The results show that the contribution to the total torque is shared by the oil flm and the asperity friction. The friction coefcient decreases sharply at frst and then increases with a change in the relative rotational speed, following the Stribeck curve closely, and the contact frictional coeffcient slowly decreases with increase in the pressure between the friction pairs. The torque between the friction pairs is provided by the asperity friction, and the torque due to the oil flm reduces to zero. When the thickness of the oil flm is small, a major contribution to the total torque is due to the asperity friction. The total torque also increases with the decrease in the flm thickness ratio. Therefore, by theoretical analysis and experimental verifcation, the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.
Hongwei Cui
,
Qiliang Wang
,
Zisheng Lian
,
Long Li
. Theoretical Model and Experimental Research on Friction and Torque Characteristics of Hydro-viscous Drive in Mixed Friction Stage[J]. Chinese Journal of Mechanical Engineering, 2019
, 32(5)
: 80
-80
.
DOI: 10.1186/s10033-019-0393-z
The hydro-viscous drive (HVD) has been widely used in fan transmission in vehicles, fans, and scraper conveyors for step-less speed regulation or soft starting. In the mixed friction stage, the contact, friction, and torque characteristics of friction pairs are very complex and change at any time. The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage. The fuid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory. In addition, the contact friction coefcient of the friction pairs was taken into consideration and measured by using the MM1000-III friction and wear testing machine. The asperity friction torque and total torque in the mixed friction stage were obtained and fnally, the test rig for the torque characteristics was set up. The results show that the contribution to the total torque is shared by the oil flm and the asperity friction. The friction coefcient decreases sharply at frst and then increases with a change in the relative rotational speed, following the Stribeck curve closely, and the contact frictional coeffcient slowly decreases with increase in the pressure between the friction pairs. The torque between the friction pairs is provided by the asperity friction, and the torque due to the oil flm reduces to zero. When the thickness of the oil flm is small, a major contribution to the total torque is due to the asperity friction. The total torque also increases with the decrease in the flm thickness ratio. Therefore, by theoretical analysis and experimental verifcation, the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.
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