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Abstract
Experimental and theoretical investigation was conducted to
measure the friction forces between vane tip and cam-ring in oil vane
pumps. The incentive of this work is to study the effect of important
parameters on the coefficient of friction between vane tip and cam-ring.
Such parameters are relative speed between vane tip and cam-ring,
normal vane force, pressure difference between the two sides of the vane,
vane tip radius of curvature, and coating of the vane tip. A comparison
was performed between five different (Physical Vapor Deposition) PVD-
coated vane tips and the normal vane without coating. To satisfy such
requirements a special test rig was designed and constructed in the lab. A
computer program was also developed to solve the Elaso-Hydrodynamic
Lubriction (EHL) film. Finite deference technique was used to solve
Navier Stock’s and energy equations in order to calculate the friction in
the vane tip due to the shear of the lubricant. Validation of the computer
model was tested using the experimental results. The results show that
the effect of normal vane force and pressure difference between the two
sides of the vane are very small compared to the relative speed. The
coating material shows no significant effect on the friction force in oil
vane pumps. Therefore the wear properties of the coating materials
should be considered in future studies. For friction measurements in oil
vane pumps a simple test rig design with no pressure difference between
the two sides of the vane is proposed.