Let us come to the model that we have used to optimise the mechanism that
we have seen before. When we want to minimise the wear we have to keep as
high as possible the height of the lubricant film between the rocker and
the cam. We resort to the hydroelastic theory.
- h is the height of the film between the rocker and the cam;
- µ is the viscosity of the lubricant;
- w is the velocity, which is related to the flow of the lubricant
within the two surfaces in contact each other;
- R is a medium radius of curvature of the two surfaces, say
rocker and cam surface;
- a is the kinematic viscosity;
- l is the cross of the surfaces, which are in contact;
- E is a parameter which refers to the young module of the two
surfaces which are in contact;
- F is the force exchanged between the two surfaces.
We have obviously to avoid h to fall below a specific value in order
to avoid a contact between the heights of the roughness of the two surfaces
which are in contact.
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