Patent ID: 8171631

Claim:
A positioning method used in a process of assembling a scroll-type fluid machine from a semifinished assembly which has been prepared by inserting a rotary shaft into a rotary shaft bearing provided in a frame, 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 method comprising the steps of: (a) holding said frame of said semifinished assembly; (b) holding said stationary scroll in such a manner that said stationary scroll can move both horizontally and vertically; (c) exerting a horizontal thrust on said stationary scroll, thereby causing said rotary shaft to incline in a direction opposite to a direction in which the eccentric shaft end portion of said rotary shaft is oriented; (d) turning said rotary shaft while varying rotational phase of the horizontal thrust exerted on said stationary scroll in synchronism with rotational phase of said rotary shaft; (e) determining an orbital path of said stationary scroll by measuring displacements thereof; (f) incrementally pressing said stationary scroll against said frame; (g) evaluating stability of the orbital path of said stationary scroll determined in step (e) above based on measurement values of the displacements of said stationary scroll in each successive pressing stage of step (f) above; and (h) determining a fixing point on which said stationary scroll is to be fixedly centered with respect to said frame if the orbital path of said stationary scroll is judged to be stable.