US 12,078,187 B2
Impeller, fan, and air-conditioning apparatus
Shota Morikawa, Tokyo (JP); Tomoya Fukui, Tokyo (JP); Koyuki Nagashima, Tokyo (JP); and Takashi Ikeda, Tokyo (JP)
Assigned to MITSUBISHI ELECTRIC CORPORATION, Tokyo (JP)
Appl. No. 17/292,450
Filed by Mitsubishi Electric Corporation, Tokyo (JP)
PCT Filed Dec. 26, 2018, PCT No. PCT/JP2018/047789
§ 371(c)(1), (2) Date May 10, 2021,
PCT Pub. No. WO2020/136750, PCT Pub. Date Jul. 2, 2020.
Prior Publication US 2021/0324874 A1, Oct. 21, 2021
Int. Cl. F04D 29/38 (2006.01); F04D 29/32 (2006.01); F04D 29/52 (2006.01)
CPC F04D 29/384 (2013.01) [F04D 29/325 (2013.01); F04D 29/522 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An impeller comprising:
a boss provided on a rotation axis; and
a blade provided on an outer circumferential side of the boss, the blade having
a leading edge that is a front one of edges of the blade in a rotation direction of the blade,
a trailing edge that is a rear one of the edges of the blade in the rotation direction,
an outer circumferential edge that is an outer circumferential one of the edges of the blade,
an inner circumferential edge that is an inner circumferential one of the edges of the blade, and
a radially middle portion that is located midway between the outer circumferential edge and the inner circumferential edge in a radial direction of the blade from the rotation axis,
where at cylindrical sections of the blade that are located around the rotation axis, a line connecting points that are located from the inner circumferential edge to the outer circumferential edge such that at each of the cylindrical sections, a ratio between a distance from the leading edge to an associated one of the points and a distance from the trailing edge to the associated point is equal to each of those at the others of the cylindrical sections is a span line, and a section of the blade that is taken along the span line and in parallel with the rotation axis is a span-direction section,
a span-direction section of part of the blade that adjoins the leading edge is shaped such that part of a suction side of the blade that is located in an area between the radially middle portion and the outer circumferential edge is concave, and a span-direction section of part of the blade that adjoins the trailing edge is shaped such that part of the suction side of the blade that is located in the area between the radially middle portion and the outer circumferential edge is convex, and
wherein the cylindrical sections of the blade that are located around the rotation axis include cylindrical sections that are taken along the radially middle portion, taken at a location inward of the radially middle portion, and taken at a location outward of the radially middle portion, and each of the taken cylindrical sections is shaped such that the suction side is convex, and does not have an inflection point between the leading edge and the trailing edge.