Air Blowing Unit For Vehicle

Abstract

Provided is an air blowing unit for a vehicle which, even when a backflow prevention means which prevents the flow of air which flows back through a gap formed between a bottom surface of an impeller and an upper surface of a motor flange is adopted, optimally maintains a size of the gap thus suppressing noises and the collection of moisture and, can suitably boost a pressure of air in a scroll case portion. With respect to a case of an air blowing unit, a projecting portion is formed in a projecting manner on an inner side of a second wall portion on a side opposite to a first wall portion where an air suction port is formed as an air backflow prevention means. The projecting portion is positioned outside an impeller in the radial direction with a predetermined gap between a radial outer end of the impeller and the projecting portion.

1 . An air blowing unit for a vehicle comprising:
 an air blowing means which includes an impeller and a motor which rotatably drives the impeller by way of a rotary shaft; and   a case which includes a scroll case portion which encases the impeller of the air blowing means, an air blowing passage which gradually expands toward the outside of the impeller in the radial direction from a winding start to a winding end of the scroll case portion being formed in the scroll case portion, wherein   an air suction port for sucking air into the case from the outside is formed in a first wall portion of the case positioned on one side in the axial direction of the impeller, and an air blow-off port for blowing off air to the outside of the case is formed in a winding-end-side portion of the scroll case portion, wherein   an air backflow prevention means is provided to an inner side of a second wall portion of the case positioned on the other side in the axial direction of the impeller, and   the air backflow prevention means is positioned outside a radial outer end of the impeller in the radial direction with a predetermined gap formed between the air backflow prevention means and a radial outer end of the impeller whereby the flow of air which moves into the air blowing passage from a radial outer side of the impeller is adjusted so as to allow the air which moves into the air blowing passage to smoothly flow toward the radial outer side of the impeller.   
     
     
         2 . The air blowing unit for a vehicle according to  claim 1 , wherein the air backflow prevention means includes a projecting portion which projects into the air blowing passage, and a surface of the projecting portion positioned on a side opposite to the impeller forms an inclined surface inclined in the direction approaching an inner surface of the second wall portion except for the projecting portion as the surface goes away from the rotary shaft. 
     
     
         3 . The air blowing unit for a vehicle according to  claim 2 , wherein the projecting portion of the air backflow prevention means has a crest portion on a first wall portion side, and the crest portion is arranged at the substantially same position as an end portion of the impeller which is positioned on an outer side of the impeller in the radial direction and on a second wall portion side in the axial direction of the impeller as viewed from a radial direction side of the impeller. 
     
     
         4 . The air blowing unit for a vehicle according to  claim 3 , wherein the projecting portion of the air backflow prevention means has a flat surface or a curved surface on the crest portion thereof. 
     
     
         5 . The air blowing unit for a vehicle according to  claim 2 , wherein an inner surface of a portion of the second wall portion which is positioned on a side opposite to the impeller by setting the projecting portion as a base point is arranged so as to be relatively away from an inner surface of the first wall portion thus forming an expanding portion in the air blowing passage. 
     
     
         6 . The air blowing unit for a vehicle according to  claim 1 , wherein the air backflow prevention means includes a stepped portion which is constituted of a stepped surface which is formed by arranging an inner surface of a portion of the second wall portion positioned outside the impeller in the radial direction relatively close to the inner surface of the first wall portion and a elected surface which is contiguously joined to the stepped surface on an impeller side, and the stepped surface of the stepped portion and an end portion of the impeller which is positioned outside the impeller in the radial direction and on a second wall portion side in the axial direction of the impeller are arranged at the substantially same position as viewed in an impeller radial direction side. 
     
     
         7 . The air blowing unit for a vehicle according to  claim 1 , wherein
 the air backflow prevention means differs in constitution at least between a portion of the second wall portion corresponding to a winding start portion of the scroll case portion and a portion of the second wall portion corresponding to a winding end portion of the scroll case portion,   the air backflow prevention means at the portion of the second wall portion corresponding to the winding start portion of the scroll case portion includes a stepped portion which is constituted of a stepped surface which is formed by arranging an inner surface of a portion of the second wall portion positioned outside the impeller in the radial direction relatively close to the inner surface of the first wall portion and a erected surface which is contiguously joined to the stepped surface on an impeller side,   the air backflow prevention means at the portion of the second wall portion corresponding to the winding end portion of the scroll case portion includes a projecting portion which projects into the air blowing passage, and   an inner surface of a portion of the second wall portion which is positioned on a side opposite to the impeller by setting the projecting portion as a base point is arranged relatively away from the inner surface of the first wall portion thus forming an air blowing amount increasing portion having a larger cross-sectional area than a portion having the stepped portion in the air blowing passage.   
     
     
         8 . The air blowing unit for a vehicle according to  claim 3 , wherein an inner surface of a portion of the second wall portion which is positioned on a side opposite to the impeller by setting the projecting portion as a base point is arranged so as to be relatively away from an inner surface of the first wall portion thus forming an expanding portion in the air blowing passage. 
     
     
         9 . The air blowing unit for a vehicle according to  claim 4 , wherein an inner surface of a portion of the second wall portion which is positioned on a side opposite to the impeller by setting the projecting portion as a base point is arranged so as to be relatively away from an inner surface of the first wall portion thus forming an expanding portion in the air blowing passage. 
     
     
         10 . The air blowing unit for a vehicle according to  claim 1 , wherein the air backflow prevention means includes a projecting portion which projects into the air blowing passage. 
     
     
         11 . The air blowing unit for a vehicle according to  claim 1 , wherein the air backflow prevention means includes a stepped portion.