Scroll fluid machine having surface coating layers on wraps thereof

In a scroll fluid machine comprising a casing;

• a fixed scroll member integral with said casing, said fixed scroll member having a spiral wrap standing on an end plate;
• a driving shaft rotatably supported at a proximal end thereof by said casing, said driving shaft having a distal end portion extending into said casing;
• and an orbiting scroll member orbitably provided on the distal end portion of said driving shaft, said orbiting scroll member having a spiral wrap standing on an end plate so as to overlap said wrap of said fixed scroll member to define a plurality of compression chambers therebetween;
• the improvement which comprises:
• a surface coating layer formed on at least either one of the wraps of said orbiting scroll member and fixed scroll member, said surface coating layer being made of a material less rigid than said wraps;
• an orbiting radius varying mechanism provided between the distal end of said driving shaft and said orbiting scroll member to vary an orbiting radius of said orbiting scroll member;
• a stopper mechanism provided on said orbiting radius varying mechanism to limit a variation in the orbiting radius of said orbiting scroll member to a value smaller than the thickness of said surface coating layer;
• and
• said orbiting radius varying mechanism having a variable crank comprising a first shaft rotatable mounted on the distal end of said driving shaft with an eccentricity with respect to an axis of said driving shaft, and a second shaft for rotatable supporting said orbiting scroll member, said second shaft being eccentric with respect to both an axis of said first shaft and the axis of said driving shaft, said stopper mechanism being arranged to limit relative rotation between said variable crank and said driving shaft to a predetermined rotation angle.