Outdoor unit for air-conditioning apparatus

Abstract

An outdoor unit for an air-conditioning apparatus includes a bellmouth having a first tapered portion with an inner diameter in upstream of the bellmouth from which air flows being larger than that in downstream of the bellmouth, and a straight pipe portion extending straight from the first tapered portion to the downstream side of airflow. The first tapered portion includes a first bend portion forming an air inlet, a second bend portion connecting to the straight pipe portion and having an inner diameter smaller than that of the first bend portion, and a connection portion connecting to the first bend portion and the second bend portion and having an inner surface extending straight. A length of at least a part of the first tapered portion along an axial direction of the straight pipe portion is larger than the straight pipe portion along the axial direction of the straight pipe portion.

1 . An outdoor unit for an air-conditioning apparatus, comprising:
 a heat exchanger;   an axial flow fan configured to generate flow of air passing through the heat exchanger;   a casing having an opening through which the air passes, the casing accommodating the heat exchanger, and accommodating the axial flow fan between the opening and the heat exchanger; and   a bellmouth having an annular shape and provided around the axial flow fan inside the casing to guide the air into the opening of the casing,   the bellmouth having
 a first tapered portion in which an inner diameter of an upstream side of the first tapered portion from which the air flows in is larger than an inner diameter of a downstream side of the first tapered portion, and 
 a straight pipe portion extending straight from the first tapered portion to the downstream side of the flow of the air, 
   wherein
 the first tapered portion includes
 a first bend portion forming an inlet for the air, 
 a second bend portion connecting to the straight pipe portion and having an inner diameter smaller than that of the first bend portion, and 
 a connection portion connecting to the first bend portion and the second bend portion and having an inner surface extending straight, and 
 
 a length of at least a part of the first tapered portion along an axial direction of the straight pipe portion is larger than a length of the straight pipe portion along the axial direction of the straight pipe portion, 
   wherein the second curvature radius of the second bend portion varies in a circumferential direction of the bellmouth.   
     
     
         2 . The outdoor unit for an air-conditioning apparatus of  claim 1 , wherein a first curvature radius of the first bend portion is larger than a second curvature radius of the second bend portion. 
     
     
         3 . The outdoor unit for an air-conditioning apparatus of  claim 2 , wherein the first curvature radius of the first bend portion varies in a circumferential direction of the bellmouth. 
     
     
         4 . The outdoor unit for an air-conditioning apparatus of  claim 1 , wherein a length of the inner surface of the connection portion, the inner surface extending straight, varies in the circumferential direction of the bellmouth. 
     
     
         5 . The outdoor unit for an air-conditioning apparatus of  claim 1 , wherein a first central angle of the first bend portion varies in the circumferential direction of the bellmouth. 
     
     
         6 . The outdoor unit for an air-conditioning apparatus of  claim 1 , wherein a second central angle of the second bend portion varies in the circumferential direction of the bellmouth. 
     
     
         7 . The outdoor unit for an air-conditioning apparatus of  claim 1 , wherein
 the heat exchanger has an L shape in top view,   the heat exchanger includes
 a first portion extending in a direction crossing a direction along a shaft of the axial flow fan, and 
 a second portion extending in a direction crossing the first portion, the second portion being spaced apart from the first tapered portion, 
   an inner surface of the first bend portion is formed by a first upstream region and a second upstream region,   the first upstream region and the second upstream region are formed by respective first edge lines extending from the upstream side of the bellmouth from which the air flows in toward the downstream side of the bellmouth,   one of the first edge lines forming the first upstream region bulges toward an inside of the bellmouth,   the second portion is disposed on an extension of the one of the first edge lines forming the first upstream region,   the second portion is not disposed on an extension of an other of the first edge lines forming the second upstream region,   an inner surface of the second bend portion is formed by a first downstream region and a second downstream region,   the first downstream region and the second downstream region are formed by respective second edge lines bulging toward the inside of the bellmouth,   one of the second edge lines forming the first downstream region is disposed on an extension of the one of the first edge lines forming the first upstream region, and   an other of the second edge lines forming the second downstream region is disposed on an extension of the other of the first edge lines forming the second upstream region.   
     
     
         8 . The outdoor unit for an air-conditioning apparatus of  claim 7 , wherein a first curvature radius of each of the first edge lines is larger than a second curvature radius of each of the second edge lines. 
     
     
         9 . The outdoor unit for an air-conditioning apparatus of  claim 8 , wherein a first central angle of the one of the first edge lines forming the first upstream region differs from a first central angle of the other of the first edge lines forming the second upstream region. 
     
     
         10 . The outdoor unit for an air-conditioning apparatus of  claim 9 , wherein the first central angle of the one of the first edge lines forming the first upstream region is smaller than the first central angle of the other of the first edge lines forming the second upstream region. 
     
     
         11 . The outdoor unit for an air-conditioning apparatus of  claim 7 , wherein the first curvature radius of the one of the first edge lines forming the first upstream region differs from the first curvature radius of the other of the first edge lines forming the second upstream region. 
     
     
         12 . The outdoor unit for an air-conditioning apparatus of  claim 7 , wherein a second central angle of the one of the second edge lines forming the first downstream region differs from a second central angle of the other of the second edge lines forming the second downstream region. 
     
     
         13 . The outdoor unit for an air-conditioning apparatus of  claim 7 , wherein the second curvature radius of the one of the second edge lines forming the first downstream region differs from the second curvature radius of the other of the second edge lines forming the second downstream region. 
     
     
         14 . The outdoor unit for an air-conditioning apparatus of  claim 7 , wherein
 the inner surface of the connection portion is formed by a first intermediate region and a second intermediate region,   the first intermediate region and the second intermediate region are formed by respective third edge lines that are straight,   one of the third edge lines forming the first intermediate region connects to the one of the first edge lines forming the first upstream region and the one of the second edge lines forming the first downstream region to be located between the one of the first edge lines and the one of the second edge lines,   an other of the third edge lines forming the second intermediate region connects to the other of the first edge lines forming the second upstream region and the other of the second edge lines forming the second downstream region to be located between the other of the first edge lines and the other of the second edge lines, and   a length of the one of the third edge lines forming the first intermediate region differs from a length of the other of the third edge lines forming the second intermediate region.   
     
     
         15 . The outdoor unit for an air-conditioning apparatus of  claim 14 , wherein the length of the one of the third edge lines forming the first intermediate region is shorter than the length of the other of the third edge lines forming the second intermediate region. 
     
     
         16 . The outdoor unit for an air-conditioning apparatus of  claim 1 , wherein a length of the first tapered portion along the axial direction of the straight pipe portion varies in the circumferential direction. 
     
     
         17 . The outdoor unit for an air-conditioning apparatus of  claim 1 , wherein the bellmouth further has a second tapered portion connecting to the straight pipe portion and the opening of the casing, the second tapered portion having an inner diameter increasing in a direction from the straight pipe portion located at the upstream side toward the opening located at the downstream side. 
     
     
         18 . The outdoor unit for an air-conditioning apparatus of  claim 17 , wherein a second opening length of an end portion located downstream of the second tapered portion is larger than a first opening length of an end portion located upstream of the first tapered portion. 
     
     
         19 . An outdoor unit for an air-conditioning apparatus, comprising:
 a heat exchanger;   an axial flow fan configured to generate flow of air passing through the heat exchanger;   a casing having an opening through which the air passes, the casing accommodating the heat exchanger, and accommodating the axial flow fan between the opening and the heat exchanger; and   a bellmouth having an annular shape and provided around the axial flow fan inside the casing to guide the air into the opening of the casing,   the bellmouth having
 a first tapered portion in which an inner diameter of an upstream side of the first tapered portion from which the air flows in is larger than an inner diameter of a downstream side of the first tapered portion, and 
 a straight pipe portion extending straight from the first tapered portion to the downstream side of the flow of the air, 
   wherein
 the first tapered portion includes
 a first bend portion forming an inlet for the air, 
 a second bend portion connecting to the straight pipe portion and having an inner diameter smaller than that of the first bend portion, and 
 a connection portion connecting to the first bend portion and the second bend portion and having an inner surface extending straight, and 
 
 a length of at least a part of the first tapered portion along an axial direction of the straight pipe portion is larger than a length of the straight pipe portion along the axial direction of the straight pipe portion, 
   wherein the first curvature radius of the first bend portion varies in a circumferential direction of the bellmouth.