Centrifugal air-sending device and air-conditioning apparatus

Abstract

A centrifugal air-sending device includes a fan and a scroll casing. The scroll casing has a tongue portion and an extension plate. The extension plate is plate-shaped and extends from the tongue portion. The extension plate has one portion that is closer to a side plate than is another portion of the extension plate that is closer to a main plate than is the one portion. The one portion is formed longer than the other portion. The extension plate has an extreme distal end. The scroll casing has, when projected in an axial direction of a rotation axis, a tongue-portion-side end that is located in a discharge-port edge that is a portion that corresponds to a discharge port. The tongue-portion-side end is located opposite to the extreme distal end in a circumferential direction across a reference line drawn perpendicular to the discharge-port edge from the rotation axis.

1 . A centrifugal air-sending device comprising:
 a fan that has a main plate that is disc-shaped, a plurality of blades located around a periphery of the main plate, and a side plate that is ring-shaped, is located such that the side plate faces the main plate, and fixes ends of the plurality of blades that are opposite to the main plate; and   a scroll casing that has a peripheral wall that is spiral-shaped, and at least one side wall that has a bell mouth that forms an air inlet that communicates with a space surrounded by the main plate and the plurality of blades, the scroll casing forming a discharge port through which airflow generated by the fan is discharged, the scroll casing housing the fan,   the scroll casing having   a tongue portion that forms a curved surface at a winding-start portion of the peripheral wall that is closer to a rotation axis of the fan than are other portions of the peripheral wall, the tongue portion guiding the airflow generated by the fan to the discharge port, and   an extension plate that is plate-shaped, projects from the tongue portion, is spaced apart from the fan, and extends from the tongue portion along an outer periphery of the fan,   the extension plate having one portion that is closer to the side plate than is an other portion of the extension plate that is closer to the main plate than is the one portion, the one portion being formed longer than the other portion in a circumferential direction of the fan, the extension plate having a distal end portion that extends in a direction of projection in which the extension plate projects from the tongue portion, the distal end portion having an extreme distal end that is located at a boundary between the distal end portion and the at least one side wall,   the scroll casing having, in a case in which the scroll casing is projected in an axial direction of the rotation axis, a tongue-portion-side end that is located in a discharge-port edge that is a portion that corresponds to the discharge port, the tongue-portion-side end being an end that is closer to the tongue portion than is an other end of the discharge-port edge, the tongue-portion-side end being located opposite to the extreme distal end in the circumferential direction across a reference line drawn perpendicular to the discharge-port edge from the rotation axis.   
     
     
         2 . The centrifugal air-sending device of  claim 1 , wherein
 the extension plate includes a basal portion that serves as a boundary between the extension plate and the tongue portion, and   the extension plate is formed such that a thickness of a plate that forms the extension plate from the basal portion to the extreme distal end is a uniform thickness that falls within a predetermined range.   
     
     
         3 . The centrifugal air-sending device of  claim 1 , wherein the extension plate is formed such that a thickness of a plate that forms the extension plate is equal to a thickness of a plate that forms the peripheral wall. 
     
     
         4 . The centrifugal air-sending device of  claim 1 , wherein each of the plurality of blades has
 a turbo blade portion including an inner circumferential end located closer to the rotation axis than is an outer circumferential end in a radial direction that starts from the rotation axis as a radial center, the turbo blade portion forming a backward-curved blade, and   a sirocco blade portion including the outer circumferential end located closer to an outer circumference of the blade than is the inner circumferential end in the radial direction, the sirocco blade portion forming a forward-curved blade.   
     
     
         5 . The centrifugal air-sending device of  claim 1 , wherein
 the at least one side wall in which the air inlet is formed includes two side walls,   the extension plate includes a first plate portion and a second plate portion that are formed in right triangular shapes when seen from the discharge port, and   the extension plate is formed such that an oblique side of the first plate portion and an oblique side of the second plate portion face each other.   
     
     
         6 . The centrifugal air-sending device of  claim 1 , wherein
 the at least one side wall in which the air inlet is formed includes two side walls, and   the extension plate has a notch cut in a V shape when seen from the discharge port.   
     
     
         7 . The centrifugal air-sending device of  claim 1 , wherein
 the at least one side wall in which the air inlet is formed includes two side walls, and   the extension plate has a notch cut in a U shape when seen from the discharge port.   
     
     
         8 . The centrifugal air-sending device of  claim 6 , wherein the extension plate has an edge portion that forms the notch and is formed in a wave shape. 
     
     
         9 . The centrifugal air-sending device of  claim 1 , wherein
 the at least one side wall in which the air inlet is formed includes two side walls,   the main plate is formed such that the main plate is shifted to one side from a center position of the fan in the axial direction of the rotation axis, and   the extension plate has a shortest portion that is a portion of the extension plate that is shortest in length in the direction of projection when seen from the discharge port, the shortest portion corresponding in position to the main plate in the axial direction of the rotation axis.   
     
     
         10 . The centrifugal air-sending device of  claim 1 , wherein the scroll casing is a single-suction casing in which the air inlet is formed only at one side of the fan in the axial direction of the rotation axis. 
     
     
         11 . The centrifugal air-sending device of  claim 10 , wherein the extension plate has an edge portion that is formed by the distal end portion and is formed in a wave shape from the other portion that is closer to the main plate to the one portion that is closer to the side plate. 
     
     
         12 . An air-conditioning apparatus comprising:
 the centrifugal air-sending device of  claim 1 ; and   a heat exchanger through which air caused by the centrifugal air-sending device to flow passes.