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An impeller, a fan apparatus, and a method of manufacturing the impeller are provided. The impeller includes a support portion, a plurality of rotor blades, and a joining member. The joining member is a substantially annular member provided to strengthen the rotor blades against influence of a centr

An impeller, a fan apparatus, and a method of manufacturing the impeller are provided. The impeller includes a support portion, a plurality of rotor blades, and a joining member. The joining member is a substantially annular member provided to strengthen the rotor blades against influence of a centrifugal force, and extends in a circumferential direction along a circle centered on a central axis so as to join the rotor blades to one another. In each of the rotor blades, a point of intersection of a leading edge of the rotor blade with a radially outer end of the rotor blade is positioned forward, with respect to a rotation direction, relative to a point of intersection of the leading edge with an outside surface of the support portion. The joining member is positioned radially inwards of the radially outer end of each of the rotor blades.

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1. An impeller comprising: a support portion centered on a central axis;a plurality of blades extending radially outward from an outside surface of the support portion, and arranged to rotate about the central axis together with the support portion to produce an airflow; anda substantially annular j

1. An impeller comprising: a support portion centered on a central axis;a plurality of blades extending radially outward from an outside surface of the support portion, and arranged to rotate about the central axis together with the support portion to produce an airflow; anda substantially annular joining member extending in a circumferential direction along an arbitrary circle centered on the central axis, and arranged to join the blades to one another; whereinin each of the blades, a point of intersection of a leading edge of the blade with a blade end of the blade is positioned forward, with respect to a rotation direction, relative to a point of intersection of the leading edge with the outside surface of the support portion, the leading edge being an edge of the blade positioned most forward with respect to the rotation direction, the blade end being a radially outer end of the blade;the joining member is positioned radially inward of the blade end of each of the blades;the support portion, the blades, and the joining member are defined together as a single continuous monolithic member of molded resin or plastic;the joining member includes two surfaces facing in opposite directions along the central axis, and at least one of the two surfaces has provided thereon at least one increased width portion defined by an increase in a radial width of the surface; andthe at least one increased width portion is a solid member that is provided in an overlapping section where the surface of the joining member on which the increased width portion is provided overlaps with one of the blades when viewed in a direction along the central axis. 2. The impeller according to claim 1, wherein the joining member is provided at a radial distance of approximately 70% to approximately 90% of a total blade length from a base of each of the blades, the total blade length being a dimension of the blade measured along a radial direction. 3. The impeller according to claim 1, wherein in each of the blades, a point of intersection of a trailing edge of the blade with the blade end is positioned forward, with respect to the rotation direction, relative to the point of intersection of the leading edge with the outside surface of the support portion, the trailing edge being an edge of the blade positioned most rearward with respect to the rotation direction. 4. The impeller according to claim 1, wherein, when each of the blades is divided into forward and rearward portions by a straight line joining the central axis and the point of intersection of the leading edge with the outside surface of the support portion, a volume of the forward portion of the respective blade is greater than a volume of the rearward portion of the respective blade, the forward and rearward portions being positioned forward and rearward, respectively, with respect to the rotation direction relative to the straight line. 5. The impeller according to claim 1, wherein, of first and second ends of the overlapping section positioned at circumferential ends thereof, the at least one increased width portion is provided in a vicinity of the first end, the first end being greater than the second end in distance from the blade along the central axis. 6. The impeller according to claim 1, wherein the at least one increased width portion defines a receiver to receive a moving portion of a mold arranged to mold the resin or plastic member, the moving portion being arranged to be movable relative to the mold to push the resin or plastic member out of the mold. 7. The impeller according to claim 1, wherein the joining member is substantially in the shape of a cylinder extending about the central axis. 8. The impeller according to claim 1, wherein the point of intersection of the blade end with the trailing edge of each of the blades, and an adjacent area, have a curve shape. 9. The impeller according to claim 1, wherein an end of the joining member on an outlet side of the impeller along the central axis is positioned more toward the outlet side than a portion of each of the blades positioned most toward the outlet side within a section of the blade which is positioned radially outward of the joining member. 10. The impeller according to claim 1, wherein within a section of each of the blades positioned radially inward of the joining member, an end of each of the blades on an outlet side of the impeller along the central axis includes a jutting portion jutting out toward the outlet side relative to an end of the joining member on the outlet side. 11. The impeller according to claim 1, wherein an end on an outlet side of the impeller along the central axis of a portion of each of the blades which intersects with an inner surface of the joining member is substantially at a same axial position as an end of the joining member on the outlet side. 12. The impeller according to claim 1, wherein an end of the joining member on an outlet side of the impeller along the central axis is positioned more toward the outlet side than an end of a portion of each of the blades which intersects with an inner surface of the joining member on the outlet side. 13. The impeller according to claim 1, wherein an end of the blade on an inlet side of the impeller along the central axis is positioned more toward an outlet side of the impeller along the central axis than an end of the joining member on the inlet side throughout a section of each of the blades which is positioned radially inward of the joining member. 14. The impeller according to claim 1, wherein an end of the joining member on an outlet side of the impeller along the central axis is positioned more on the outlet side than an end of each of the blades on the outlet side. 15. The impeller according to claim 1, wherein there is a plurality of the at least one increased width portions and each of the plurality of the at least one increased width portions is only arranged at positions that overlap the blades. 16. A fan apparatus comprising: an impeller comprising: a support portion centered on a central axis;a plurality of blades extending radially outward from an outside surface of the support portion, and arranged to rotate about the central axis together with the support portion to produce an airflow; anda substantially annular joining member extending in a circumferential direction along an arbitrary circle centered on the central axis, and arranged to join the blades to one another; whereinin each of the blades, a point of intersection of a leading edge of the blade with a blade end of the blade is positioned forward, with respect to a rotation direction, relative to a point of intersection of the leading edge with the outside surface of the support portion, the leading edge being an edge of the blade positioned most forward with respect to the rotation direction, the blade end being a radially outer end of the blade;the joining member is positioned radially inward of the blade end of each of the blades;the support portion, the blades, and the joining member are defined together as a single continuous monolithic member of molded resin or plastic; andthe joining member includes two surfaces facing in opposite directions along the central axis, and at least one of the two surfaces has provided thereon at least one increased width portion defined by an increase in a radial width of the surface; andthe at least one increased width portion is a solid member that is provided in an overlapping section where the surface of the joining member on which the increased width portion is provided overlaps with one of the blades when viewed in a direction along the central axis;a motor arranged to drive the impeller;an outer frame member arranged to surround the impeller; anda support member arranged radially inward of the outer frame member to support the motor. 17. The fan apparatus according to claim 16, wherein there is a plurality of the at least one increased width portions and each of the plurality of the at least one increased width portions is only arranged at positions that overlap the blades. 18. A method of manufacturing an impeller including: a support portion including a cylindrical outside surface centered on a central axis;a plurality of blades extending radially outward from the cylindrical outside surface of the support portion, and arranged to rotate about the central axis together with the support portion to produce an airflow; anda substantially annular joining member extending in a circumferential direction about the central axis, including two axially exposed surfaces facing in opposite directions along the central axis, and arranged to join the blades to one another; whereinat least one of the two surfaces of the joining member includes at least one increased width portion defined by an increase in a radial width of the surface and at least one decreased width portion defined by a portion of the at least one of the two surfaces that has a smaller radial width than the at least one increased width portion; andthe at least one increased width portion is provided in an overlapping section where the surface of the joining member on which the increased width portion is provided overlaps with one of the blades when viewed in a direction along the central axis;the method comprising the steps of: injecting resin or plastic into a closed space defined by a pair of molds to be separated from each other along the central axis, to define the support portion, the blades, and the joining member of the impeller integrally as a continuous resin or plastic member; andseparating the molds from each other along the central axis, while pushing the at least one increased width portion of the joining member in the resin or plastic member in a direction so as to separate the resin or plastic member from the molds, with a moving portion of the molds arranged to be movable relative to the molds along the central axis.