Load carrying capacity and friction of a parabolic-flat piston ring of finite width

Reducing the fuel consumption of a combustion engine has become a paramount design topic. As such engine friction has to be minimised. A major source of friction is the piston ring - cylinder liner contact. The current work analyses the friction and load carrying capacity of a more complex shaped piston ring consisting of a parabolic part and a flat part. This simple geometry permits an analytical solution of the pressure distribution. The flat part of the geometry can be caused by either design or wear. From the pressure distribution the load carrying capacity and the two friction forces are obtained. For the fully flooded case with an infinite inlet, the closed form solutions are supplied. For the finite width ring, solutions are given in figures as a function of the flat length L.