Injection molded centrifugal air impeller

Abstract

A centrifugal air impeller designed for injection molding has a mold parting line extending intermediate the sides of the blades thus permitting optimum configurations of the inner and outer blade edges and enhanced impeller performance. The impeller inlet ring has an inner diameter less than that of the outer edges of the blades and an outer diameter greater than the outer diameter of the blades. The backplate has a diameter greater than that of the inner diameter of the blades.

Description

[0001] (This application claims the benefit of provisional application Serial Number [not received to date] filed on Aug. 29, 2003.) BACKGROUND OF INVENTION [0002] Injection molded centrifugal air impellers with forwardly curved blades have an air flow pattern which is three dimensional. In the plane of rotation, there is a circulation that flows outwardly through the blades for approximately three hundred degrees (300°) of rotation. After passing the eye of circulation the flow reverses direction and passes back through the blades. Air flows into the blower inlet substantially along the section where the main circulation is outward. Although some air may flow out of the inlet along the section where the main circulation is inward, there is a net through flow of air out the blower discharge. The center of the main circulation is located near the inner edge of the impeller blades at the point where the flow reverses from outward to inward. Since the main circulation is larger than th...

AI Technical Summary

Benefits of technology

[0007] More particularly, the impeller design accommodates forming of an inner edge portion of each blade in the core of the mold and forming of an outer edge portion of each blade in the cavity of the mold. This allows for a proper shut off angle, which reduces the likelihood of flash at the parting line and minimizes mold wear.

[0008] As will be seen, the impeller back plate is designed so that the blades extend radially beyond the outer edge of the back plate. The inlet ring on the other hand extends radially beyond the outer edges of the blades but its inner edge resides inwardly of the blade outer edges. This ring configuration provides the required structural integrity and yet allows for a mold shut off which extends mold life and at the same time results in an aerodynamic advantage. Leakage flow around the blade ends at the inlet is inhibited and this enhances impeller performance High velocity leakage flow around the blade ends is known to disturb the inlet flow pattern and thus reduce efficiency.

Problems solved by technology

Leakage flow around the blade ends at the inlet is inhibited and this enhances impeller performance High velocity leakage flow around the blade ends is known to disturb the inlet flow pattern and thus reduce efficiency.

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