Propeller for watercraft

Abstract

A propeller includes a blade device and a driving device. The blade device includes a ring-shaped base with an inner base surface and defining a base axis, and a plurality of curved blades, each of which extends from the inner base surface of the ring-shaped base toward the base axis. The blades are angularly spaced apart from each other relative to the base axis, and cooperate to define a flow space located in the ring-shaped base at the base axis. The driving device drives the blade device to rotate about the base axis.

1 . A propeller comprising: 
 a blade device including a ring-shaped base with an inner base surface and defining a base axis, and a plurality of curved blades, each of which extends from said inner base surface of said ring-shaped base toward said base axis, said blades being angularly spaced apart from each other relative to said base axis and cooperating to define a flow space located in said ring-shaped base at said base axis; and    a driving device for driving said blade device to rotate about said base axis.    
   
   
       2 . The propeller as claimed in  claim 1 , wherein said ring-shaped base further has an outer base surface formed with gear teeth, said driving device including a drive gear meshing with said gear teeth, and a drive member for driving rotation of said drive gear.  
   
   
       3 . The propeller as claimed in  claim 1 , further comprising a retaining unit that includes an annular seat formed with an annular base retaining space that surrounds said base axis and that has said ring-shaped base retained rotatably therein.  
   
   
       4 . The propeller as claimed in  claim 3 , wherein said retaining unit further includes bearing components disposed in said base retaining space between said annular seat and said ring-shaped base.  
   
   
       5 . The propeller as claimed in  claim 4 , wherein said ring-shaped base further has first and second ends opposite to each other along said base axis, each of said first and second ends of said ring-shaped base being formed with an annular groove, said bearing components including a plurality of ball bearings received in said annular grooves in said first and second ends of said ring-shaped base.  
   
   
       6 . The propeller as claimed in  claim 1 , wherein each of said blades has a curved edge portion inclined relative to said base axis and connected to said inner base surface of said ring-shaped base, and a corner portion with a tip that extends into said flow space.