Method and system for component positioning during assembly of scroll-type fluid machine

A positioning system used in a process of assembling a scroll-type fluid machine from a semifinished assembly which has been prepared by

• fixing a frame in a shell,
• inserting a rotary shaft into a rotary shaft bearing provided in said frame,
• inserting a secondary shaft end portion of said rotary shaft into a secondary shaft end bearing provided in a sub-frame,
• fixing said sub-frame in said shell,
• assembling an orbiting scroll with said frame with an Oldham coupling placed in between such that an eccentric shaft end portion formed at one end of said rotary shaft is fitted in an eccentric shaft end bearing provided in said orbiting scroll,
• assembling a stationary scroll with said orbiting scroll such that a scroll wrap of said stationary scroll meshes with a scroll wrap of said orbiting scroll, and
• tentatively fixing said stationary scroll to said frame in such a manner that said stationary scroll is allowed to move freely relative to said frame, said positioning system comprising:
• a work retaining mechanism for holding said shell of said semifinished assembly;
• a stationary scroll retaining mechanism for holding said stationary scroll in such a manner that said stationary scroll can move both horizontally and vertically;
• a rotary shaft driving motor for turning said rotary shaft;
• a radial thrust mechanism for exerting a horizontal thrust on said stationary scroll retaining mechanism;
• a radial thrust mechanism driving motor for turning said radial thrust mechanism in synchronism with rotational phase of said rotary shaft;
• a mechanism for creating a clearance between said stationary scroll and said frame;
• a displacement sensor for measuring horizontal displacements of said stationary scroll retaining mechanism from at least two directions;
• an inclination sensor for measuring inclination of said stationary scroll retaining mechanism;
• a first processor for calculating an orbital path of said stationary scroll formed by a contact point of the scroll wrap of said stationary scroll and the scroll wrap of said orbiting scroll from measurement values of the horizontal position and inclination of said stationary scroll retaining mechanism;
• a second processor for evaluating stability of the orbital path of said stationary scroll calculated by said first processor;
• and
• a third processor for calculating a fixing point on which said stationary scroll is to be fixedly centered with respect to said frame when the orbital path of said stationary scroll is judged to be stable.