Patent ID: 8313317
Filing Date: 2012-11-20
Classification: F04C

Abstract:
1. A scroll fluid machine comprising: a crankshaft that makes a circling scroll revolve to circle around a fixed scroll fixed inside a housing; and a variable circling radius mechanism that, by pushing the circling scroll to the fixed scroll, seals a compression chamber defined by the fixed scroll and the circling scroll in a radial direction, wherein the crankshaft includes a reinforced shaft section, a circular column-like large diameter section, and an eccentric shaft section, the reinforced shaft section having a predetermined diameter is provided continuously at a driving device side of the circular column-like large diameter section of the crankshaft, and a material is produced by a step-by-step cold forging process by setting the eccentric shaft section projecting from the circular column-like large diameter section at a predetermined eccentricity ratio f from a rotation axis of the crankshaft, the circular column-like large diameter section of the crankshaft is rotatably coupled to the housing via a needle bearing, the predetermined diameter of the reinforced shaft section is set so that a deflection amount towards a side of the eccentric shaft-section, while transmitting a driving force by the crankshaft, falls within an acceptable range to stably operate the variable circling radius mechanism, and the eccentricity ratio f of the crankshaft is calculated by a following formula, and the eccentricity ratio f is set to 1≦f≦2: f=r/L, where: where f indicates the eccentricity ratio of the eccentric shaft section, r indicates a radius of the eccentric shaft section, L indicates a distance between a center of the eccentric shaft section and a driving center of the circular column-like large diameter section, ε indicates an eccentric amount of the eccentric shaft section, ρ indicates a circling radius, and α indicates an angle at which the eccentric shaft section is set.