Axial-flow fan having inner and outer blades

Abstract

There is provided an axial-flow fan which is capable of producing axial-flow wind near the outer circumference of a fan clutch to extend the functional life of the fan clutch, and which is capable of decreasing the inertia moment of an engine cooling plastic fan and hence vibration loads to be transmitted to the bearing of the fan clutch, thereby extending the structural life of the fan clutch and increasing the burst speed of the engine cooling plastic fan. The axial-flow fan includes an inner plastic hub, plural inner plastic blades each of which extends radially from the inner plastic hub and is twisted near its extending end and connected to a portion immediately below the base of the corresponding one of the outside blades, an outer plastic hub connected to the plural inner plastic blades, and plural outer plastic blades which extend radially from the outer plastic hub.

1 . An axial-flow fan fitted to an output shaft of an internal combustion engine and provided with inner and outer blades, comprising: an inner plastic hub; plural inner plastic blades each of which extends radially from the inner plastic hub and has a base side parallel to a plane of rotation and is twisted near its extending end and connected to a portion immediately below a base of the corresponding one of the outside blades; an outer plastic hub connected to the plural inner plastic blades; and plural outer plastic blades which extend radially from the outer plastic hub.  
     
     
         2 . An axial-flow fan provided with inner and outer blades according to  claim 1 , wherein a steel insert is embedded in the inner plastic hub.