Water pump impeller

Claim 1

Water pump impeller for use in a cooling water pump for an internal combustion engine comprising a metal boss with a radially inner surface for mounting on a shaft and a radially outer surface, an annular reinforcing sleeve fitting tightly around said radially outer surface of the metal boss, a metal reinforcing disk coaxially and integrally shaped on and extending from one end face of said boss, plastic encasing said boss, said reinforcing sleeve and said disk, impeller blades composed of plastic projecting from the plastic encasing said boss, said reinforcing sleeve and said disk in an outer circumferential region of the water pump impeller, said plastic extending longitudinally over and beyond said one end face of said boss, said reinforcing disk extending radially to the vicinity of said impeller blades and defining in the vicinity of said impeller blades an annular disk part, said disk between said boss and said annular disk part having a revolution paraboloid-like reinforcing region lying at an acute angle to said boss with the concave side of the paraboloid-like reinforcing region adjacent said one end face of said boss said impeller blades being placed on the concave side of said reinforcing disk and said plastic projecting over and beyond said one end face of the boss and terminating at a given radial spacing from the radially inner surface of the boss to avoid contact with the shaft on which the metal boss is mounted.