US 12,435,728 B2
Turbofan and air-conditioning apparatus
Ryutaro Asano, Tokyo (JP); Tomoya Fukui, Tokyo (JP); Kazuki Isomura, Tokyo (JP); and Makoto Kurihara, Tokyo (JP)
Assigned to MITSUBISHI ELECTRIC CORPORATION, Tokyo (JP)
Appl. No. 18/028,768
Filed by Mitsubishi Electric Corporation, Tokyo (JP)
PCT Filed Nov. 25, 2020, PCT No. PCT/JP2020/043872
§ 371(c)(1), (2) Date Mar. 28, 2023,
PCT Pub. No. WO2022/113217, PCT Pub. Date Jun. 2, 2022.
Prior Publication US 2023/0332615 A1, Oct. 19, 2023
Int. Cl. F04D 29/28 (2006.01); F04D 17/08 (2006.01); F04D 29/58 (2006.01); F24F 1/0022 (2019.01)
CPC F04D 29/281 (2013.01) [F04D 17/08 (2013.01); F04D 29/5826 (2013.01); F24F 1/0022 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A turbofan comprising:
a main plate provided with a hub to which a rotating shaft is connected, a shroud positioned so as to face the main plate, and a plurality of blades positioned between the main plate and the shroud,
each of the plurality of blades has a leading edge and a trailing edge, the trailing edge being located further from the rotating shaft than the leading edge, the leading edge being located forward in a rotational direction than the trailing edge,
when a junction point of the leading edge with the main plate is named as a first point, and an intersection of the leading edge and an imaginary plane passing through an outermost circumference of the shroud and being perpendicular to the rotating shaft is named as a second point,
a first curve, formed by projecting the leading edge onto a plane perpendicular to the rotating shaft, has a first inflection point relative to a coordinate system in which an imaginary straight line passing through the first point and the second point is an abscissa and the rotational direction side is positive in a top view as viewed in an axial direction of the rotating shaft,
the first curve has a portion that is convex in a counter-rotational direction between the first inflection point and the first point and a portion that is convex in the rotational direction between the second point and the first inflection point,
the first point is located forward of the second point in the rotational direction,
a second curve, formed by projecting the trailing edge onto the plane perpendicular to the rotating shaft, follows an arc centered on the rotating shaft in the top view as viewed in the axial direction of the rotating shaft,
a third curve, formed by projecting the trailing edge onto a cylindrical plane coaxial with the rotating shaft, is formed so as to be convex in the rotational direction, and
a junction point of the third curve and the shroud is located behind a junction point of the third curve and the main plate in the rotational direction.