Scroll casing, and air-sending device and air-conditioning apparatus which include the same

Abstract

A scroll casing accommodates a cross-flow fan, thereby forming an airflow passage, and includes a scroll section having, as an upstream end, an approach point at which the scroll section most closely approaches the fan. A region between the upstream end of the scroll section and a downstream end is divided into three regions in the flow direction of airflow. In the three regions, the distance between the center of rotation of the fan and the scroll section increases at different change rates from the upstream end to the downstream end as the scroll section is viewed at a section perpendicular to an axis of rotation of the fan. Where the three regions are a first region, a second region, and a third region in this order from an upstream side in the flow direction of the airflow, the change rate of the second region is the smallest.

1 . A scroll casing that accommodates a cross-flow fan and thereby forms an airflow passage, and comprises:
 a scroll section having, as an upstream end, an approach point at which the scroll section most closely approaches the cross-flow fan in the scroll casing, the scroll section forming an upstream side of the airflow passage,   wherein a region between the upstream end of the scroll section and a downstream end of the scroll section is divided into three regions in a flow direction of airflow that passes through the airflow passage,   the three regions are regions in which a distance between a center of rotation of the cross-flow fan and the scroll section increases at different change rates from the upstream end of the scroll section to the downstream end of the scroll section as the scroll section is viewed at a section perpendicular to an axis of rotation of the cross-flow fan, and where the three regions are a first region, a second region, and a third region in this order from an upstream side in the flow direction of the airflow, the change rate of the second region is the smallest.   
     
     
         2 . The scroll casing of  claim 1 , wherein the change rate of the first region and the change rate of the third region are individually set depending on a shape of the cross-flow fan, such that a fan input is minimized at a set air volume. 
     
     
         3 . The scroll casing of  claim 1 , wherein α 2 <α 1 <α 3  is satisfied, where α 1  is the change rate of the first region, α 2  is the change rate of the second region, and α 3  the change rate of the third region. 
     
     
         4 . The scroll casing of  claim 1 , wherein
 the scroll section is formed to extend from a height position located upstream of, in the flow direction of the airflow, a height position of the center of rotation of the cross-flow fan to a position downstream of, in the flow direction of the airflow, the height position of the center of rotation, through a side of the cross-flow fan, and   the second region is provided to extend across the height position of the center of rotation of the cross-flow fan.   
     
     
         5 . The scroll casing of  claim 4 , including a side wall located opposite to the scroll casing, with the cross-flow fan interposed between the side wall and the scroll casing,
 wherein an upstream end of the third region is located upstream of a height position of a tongue portion of the side wall.   
     
     
         6 . An air-sending device comprising: the scroll casing of  claim 1 ; and the cross-flow fan. 
     
     
         7 . An air-conditioning apparatus comprising: the air-sending device of  claim 6 ; a housing that houses the air-sending device; and a heat exchanger provided at a position where airflow generated by the air-sending device passes through.