Debris blowing and/or vacuum appliance

Abstract

A debris blowing and/or vacuum appliance. The appliance comprises a body including a fluid inlet, a fluid outlet for exhausting fluid externally of the body, a volute located in a flowpath between the fluid inlet and the fluid outlet and a centrifugal impeller located within the volute and rotatable by a motor to generate a flow of fluid, and a diffuser located immediately downstream of the centrifugal impeller between the centrifugal impeller and a volute outlet region. The diffuser comprises an annular channel surrounding the centrifugal impeller and has substantially constant radial width such that the impeller is radially spaced from the volute walls by at least the width of the diffuser. By providing such an arrangement, the efficiency of the impeller can be improved.

1 . A debris blowing and/or vacuum appliance comprising a body including:
 a fluid inlet into the body;   a fluid outlet for exhausting fluid out of the body;   a volute assembly located in a flowpath between the fluid inlet and the fluid outlet; and   an impeller located within the volute assembly and rotatable by a motor to generate a flow of fluid between the fluid inlet and the fluid outlet, the volute assembly comprising a volute outlet portion in communication with the fluid outlet; and   a diffuser located immediately downstream of the impeller between the impeller and the volute outlet portion, the diffuser comprising an annular channel surrounding the impeller and having substantially constant radial width such that the impeller is radially spaced from the volute outlet portion by at least the width of the diffuser.   
     
     
         2 . The appliance according to  claim 1 , wherein the diffuser is vaneless. 
     
     
         3 . The appliance according to  claim 2 , wherein the diffuser comprises planar annular walls defining the annular channel. 
     
     
         4 . The appliance according to  claim 3 , wherein the volute outlet portion has an expanding cross-sectional area in the downstream direction. 
     
     
         5 . The appliance according to  claim 4 , wherein the cross-sectional area increases smoothly in the downstream direction. 
     
     
         6 . The appliance according to  claim 5 , wherein the volute outlet portion has a scroll-type shape with a substantially circular cross-section. 
     
     
         7 . The appliance according to  claim 5 , wherein the volute outlet portion further comprises a tangential portion extending downstream towards the fluid outlet. 
     
     
         8 . The appliance according to  claim 7 , wherein the volute outlet portion further comprises a volute tongue defining at least a part of the tangential portion. 
     
     
         9 . The appliance according to  claim 8 , wherein the volute tongue is radially spaced from the impeller by a distance at least equal to the width of the diffuser. 
     
     
         10 . The appliance according to  claim 9 , further comprising a suction tube, the suction inlet being formed at a distal end of the suction tube. 
     
     
         11 . The appliance according to  claim 10 , wherein the impeller is arranged, in use, to receive and to mulch dirt and debris drawn in through the suction inlet. 
     
     
         12 . The appliance according to  claim 11 , further comprising a debris collector located downstream of the fluid outlet and arranged, in use, to collect dirt and debris drawn in through the suction inlet. 
     
     
         13 . The appliance according to  claim 12  in the form of a debris blowing appliance, the appliance further comprising a blower tube, the fluid outlet being formed at a distal end of the blower tube.