Fan device and vacuum cleaner including the same

Abstract

A fan device includes the following elements. An impeller rotates around a central axis. A motor rotates the impeller positioned above the motor. A motor housing houses the motor. A fan casing forms a flow passage. An upper side of the fan casing covers the impeller and has a suction inlet. A lower side of the fan casing has an evacuate outlet communicating with the suction inlet via the flow passage. The impeller includes a base unit enlarged downward and plural blades arranged on the base unit. An impeller projection is formed on a bottom surface of the base unit. A groove denting downward is formed on a top surface of the motor housing. At least part of the impeller projection is housed within the groove.

What is claimed is: 
     
         1 . A fan device comprising:
 an impeller that rotates around a central axis extending in a top-bottom direction;   a motor that is disposed farther downward than the impeller and rotates the impeller;   a motor housing that houses the motor; and   a fan casing that houses the impeller and the motor housing and forms a flow passage in a gap between the fan casing and the motor housing,   wherein   an upper side of the fan casing covers an upper side of the impeller and has a suction inlet which is opened in the top-bottom direction,   a lower side of the fan casing has an evacuate outlet which communicates with the suction inlet via the flow passage,   the impeller includes
 a base unit that is enlarged toward a downward direction, and 
 a plurality of blades that are arranged side by side on an outer peripheral surface of the base unit in a circumferential direction, 
   a ring-like impeller projection is formed on a bottom surface of the base unit,   a ring-like groove denting downward is formed on a top surface of the motor housing, and   at least part of the impeller projection is housed within the groove.   
     
     
         2 . The fan device according to  claim 1 , wherein an outer peripheral end of the top surface of the motor housing is positioned farther upward than a lower end of the impeller projection. 
     
     
         3 . The fan device according to  claim 2 , wherein a lower end of the groove is positioned farther downward than an outer peripheral end of the top surface of the motor housing. 
     
     
         4 . The fan device according to  claim 1 , wherein:
 an outer peripheral surface of the impeller projection extends downward and inward in a radial direction from an outer edge of the base unit; and   a side wall of the groove on an outer side in the radial direction extends downward and inward in the radial direction from an outer peripheral end of the top surface of the motor housing.   
     
     
         5 . The fan device according to  claim 4 , wherein a gap is formed between the side wall of the groove on the outer side in the radial direction and the outer peripheral surface of the impeller projection, and a distance of the gap on the outer side in the radial direction is equal to a distance of the gap on an inner side in the radial direction. 
     
     
         6 . The fan device according to  claim 4 , wherein:
 an inner peripheral surface of the impeller projection and a side wall of the groove on an inner side in the radial direction extend upward and inward in the radial direction; and   a distance of a gap between the inner peripheral surface of the impeller projection and the side wall of the groove on the inner side in the radial direction is smaller than a distance of a gap between the outer peripheral surface of the impeller projection and the side wall of the groove on the outer side in the radial direction.   
     
     
         7 . The fan device according to  claim 6 , wherein a plurality of recesses are formed in the top-bottom direction on the side wall of the groove on the inner side in the radial direction. 
     
     
         8 . The fan device according to  claim 1 , wherein:
 a protruding portion protruding upward is formed on the top surface of the motor housing; and   an outer peripheral surface of the protruding portion forms a side wall of the groove on an inner side in a radial direction.   
     
     
         9 . The fan device according to  claim 8 , wherein an upper end of the protruding portion is positioned farther upward than a lower end of the impeller projection. 
     
     
         10 . The fan device according to  claim 8 , wherein an upper end of the protruding portion is positioned farther upward than an outer peripheral end of the top surface of the motor housing. 
     
     
         11 . The fan device according to  claim 1 , wherein, on a cross section including the central axis, the outer peripheral surface of the base unit and an outer peripheral surface of the motor housing are positioned on a straight line or a smooth curve in the vicinity of the groove. 
     
     
         12 . The fan device according to  claim 1 , wherein a side wall of the groove on an outer side in a radial direction is parallel with a surface of rotation of a lower edge of the blade. 
     
     
         13 . The fan device according to  claim 12 , wherein, on a cross section including the central axis, the surface of rotation is perpendicular to the outer peripheral surface of the base unit. 
     
     
         14 . The fan device according to  claim 12 , wherein:
 a plurality of stationary blades are arranged side by side on an outer peripheral surface of the motor housing in the circumferential direction; and   an upper edge of each of the stationary blades is parallel with the surface of rotation.   
     
     
         15 . The fan device according to  claim 14 , wherein a sectional area of a lower end of the flow passage between the stationary blades adjacent to each other in the circumferential direction is larger than a sectional area of an upper end of the flow passage between the stationary blades adjacent to each other in the circumferential direction. 
     
     
         16 . A vacuum cleaner comprising:
 the fan device according to  claim 1 .