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Centrifugal fan inlet orifice and impeller assembly

  • US 5,478,201 A
  • Filed: 06/13/1994
  • Issued: 12/26/1995
  • Est. Priority Date: 06/13/1994
  • Status: Expired due to Term
First Claim
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1. An apparatus for moving air comprising:

  • an inlet orifice structure (10) comprising a surface having an axisymmetric orifice leading edge (101),an axisymmetric throat (102) in downstream air flow relationship with said orifice leading edge and extending from said leading edge to an orifice trailing edge (103),said throat being in form like a surface produced by rotating a first planar line (L1) about a coplanar axis of generation (AG),said first planar line being a generally quarter segment of a first ellipse having a major axis (ASMO) that is substantially parallel to said axis of generation and a semiminor axis (ASmO); and

    a fan impeller (20) of the centrifugal flow type havingan axis of rotation (AG) that is, when assembled for operation with said inlet orifice structure, coincident with said axis of generation of said orifice structure,an impeller hub plate (202) having an inner face (2021) and centered on said axis of rotation;

    thirteen blades (203),each having a root (2031) and a tip (2032), and affixed at said root to and extending generally outward from said inner face,arranged with an angular spacing between similar points on adjacent blades of 31.85°

    , 24°

    , 30.25°

    , 31°

    , 24.9°

    , 22.75°

    , 28.25°

    , 32.15°

    , 27.25°

    , 29.5°

    , 26.6°

    23.25° and

    28.25°

    ,backwardly swept with respect to a preferred direction of rotation of said impeller;

    an axisymmetric orificed shroud (201) affixed to said blade tips and havinga shroud leading edge (2011) and a shroud trailing edge (2012), with respect to air flow through said shroud orifice,a diffuser (2013) extending from said shroud leading edge to said shroud trailing edge,said diffuser being in form like a surface produced by rotating a second planar line (L2) about a coplanar axis of generation that is coincident with said axis of rotation,said second planar line being a generally quarter segment of a second ellipse having a semimajor axis (ASMS) substantially parallel to said axis of generation and a semiminor axis (ASmS) anda portion of said diffuser adjacent said leading edge having an inner radius (RIS) sufficient to allow, when said fan impeller and said inlet orifice structure are assembled for operation, said diffuser portion to overlap and freely rotate about said throat portion of said orifice structure.

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