Automotive HVAC Diffuser With Cooperating Wall Guide And Vane

Abstract

A case for an HVAC system has at least two molded shells joined together along a parting line to enclose a heat exchanger chamber, a blower chamber, and a diffuser section. The diffuser section includes a floor, a ceiling, an outer wall, and an inner wall around a longitudinal axis. The walls provide an airflow path through the diffuser between the blower and heat exchanger chamber, and the airflow path makes a substantially right angle turn into the heat exchanger chamber which results in a tendency to create a high flow region at the outer wall because of centrifugal effects. The outer wall is shaped to form a wall guide partially projecting into the airflow path in the diffuser, wherein the wall guide has an upstream encroaching surface and a downstream retreating surface so that a portion of the guided air is directed from the outer wall toward the inner wall. At least one of the floor or the ceiling includes a vane projecting into and deflecting the guided air in the airflow path, wherein the vane has an upstream end proximate to the wall guide and a downstream end extending toward the heat exchanger chamber for initiating a portion of the substantially right angle turn for a portion of the airflow.

1 . A case for an HVAC system in a transportation vehicle, comprising at least two molded shells joined together along a parting line to receive a heat exchanger and a blower, wherein the shells enclose a heat exchanger chamber, a blower chamber, and a diffuser section for guiding air from the blower chamber to the heat exchanger chamber;
 wherein the diffuser section includes a floor, a ceiling, an outer wall, and an inner wall around a longitudinal axis between an inlet and an outlet;   wherein the walls provide an airflow path through the diffuser between the blower and heat exchanger chamber, and wherein the airflow path makes a substantially right angle turn before entering the heat exchanger chamber which results in a tendency to create a high flow region at the outer wall because of centrifugal effects;   wherein the outer wall is shaped to form a wall guide partially projecting into the airflow path in the diffuser, wherein the wall guide has an upstream encroaching surface and a downstream retreating surface so that a portion of the guided air is directed from the outer wall toward the inner wall; and   wherein at least one of the floor or the ceiling includes a vane projecting into and deflecting the guided air in the airflow path, wherein the vane and wall guide cooperate to mutually direct the guided air from the outer wall toward the inner wall.   
     
     
         2 . The case of  claim 1  wherein the vane extends to a first height which is less than about 70 percent of a height of the parting line, and wherein the wall guide spans a region around the parting line. 
     
     
         3 . The case of  claim 1  wherein the vane has an upstream end proximate to the wall guide and a downstream end extending toward the heat exchanger chamber for initiating a portion of the substantially right angle turn for a portion of the airflow. 
     
     
         4 . The case of  claim 1  wherein at least a portion of the upstream end of the vane extends substantially parallel to the local flow so that a region of the airflow path between the vane and the downstream returning surface has an increasing cross-sectional area that causes guided air passing through the region to have a reduction in speed by the Bernoulli Effect. 
     
     
         5 . The case of  claim 1  wherein the downstream end of the vane has an extended teardrop shape. 
     
     
         6 . The case of  claim 1  wherein the upstream encroaching surface of the wall guide includes a generally concave shape with a radius of curvature in the range of about 15 to about 100 millimeters. 
     
     
         7 . The case of  claim 1  wherein the downstream retreating surface of the wall guide includes a generally concave shape with a radius of curvature greater than about 100 millimeters. 
     
     
         8 . The case of  claim 1  wherein the wall guide further includes a transition between the upstream encroaching surface and the downstream retreating surface having a generally convex shape with a radius of curvature less than about 40 millimeters. 
     
     
         9 . The case of  claim 1  wherein the cooperation of the wall guide and vane is comprised of the wall guide and vane being disposed in a side-by-side relationship to define a curved air channel, whereby the guided air is deflected along a curving trajectory toward the heat exchanger chamber.