Fan unit having blades manufactured by blow molding and made from thermoplastic elastomer

Abstract

A fan unit includes a fan casing and a plurality of blades extending radially and outwardly from the fan casing. Each of the blades includes a hollow blade body that is made from a thermoplastic elastomer, that is manufactured by a blow molding process, and that is exposed outwardly from the fan casing, and a coupler element that is fixed to the blade body and that is clamped between front and rear casing halves of the fan casing.

I claim:  
     
         1 . A fan unit comprising: 
 a motor having an output shaft;    a fan casing mounted non-rotatably on said output shaft of said motor and including an annular rear casing half having a plurality of angularly spaced-apart groove units, and an annular front casing half disposed in front of said rear casing half and having a plurality of angularly spaced-apart groove units;    a plurality of blades mounted on and extending radially and outwardly from said front and rear casing halves, each of said blades including a hollow blade body that is made from a thermoplastic elastomer, that is manufactured by a blow molding process and that is exposed outwardly from said front and rear casing halves, and a coupler element that is fixed to said blade body, that is clamped between said front and rear casing halves and that has a rearwardly-extending tongue unit received snugly in a respective one of said groove units in said rear casing half, and a frontwardly-extending tongue unit received snugly in a respective one of said groove units in said front casing half; and    a fastener unit for fastening said front and r ear casing halves securely so as to prevent removal of said blades from said front and rear casing halves.    
     
     
         2 . The fan unit as defining in  claim 1 , wherein said rear casing half includes an annular outer wall with a front end, an annular inner wall that is disposed coaxially in said outer wall to define a shaft hole which permits extension of said output shaft of said motor therethrough and that has a front end flush with said front end of said outer wall, and a plurality of angularly spaced-apart rods that extend radially and outwardly from said front end of said inner wall to said front end of said outer wall to form a plurality of parallel grooves which constitute a respective one of said groove units in said rear casing half, and wherein said front casing half includes an outer wall that is aligned with said outer wall of said rear casing half and that has a rear end, an inner wall that is disposed coaxially in said outer wall, and that has a rear end flush with said rear end of said outer wall of said front casing half, and a plurality of angularly spaced-apart rods that extend radially and outwardly from said rear end of said inner wall of said front casing half to said rear end of said outer wall of said front casing half to form a plurality of parallel grooves which constitute a respective one of said groove units in said front casing half.  
     
     
         3 . The fan unit as defined in  claim 2 , wherein said output shaft of said motor has an annular outer wall surface that is formed with a planar portion, said rear casing half further including a coupling tube that extends coaxially and frontwardly from said front end of said inner wall of said rear casing half through said inner wall of said front casing half, and that has an external thread portion and an inner wall surface formed with a planar portion which engages said planar portion of said outer wall surface of said output shaft to prevent relative rotation therebetween, said fastener unit being threadedly mounted on said external thread portion of said coupling tube so as to press said front casing half against said rear casing half, thereby preventing relative rotation between said front and rear casing halves.  
     
     
         4 . The fan unit as defined in  claim 3 , wherein said coupler element of each of said blades has a tongue-mounting strip which extends in a radial direction of said fan casing and which is formed with two opposite side faces, each of said rearwardly and frontwardly extending tongue units including a plurality of tongues that are formed integrally with a corresponding one of said opposite side faces of said tongue-mounting strips, said tongues of said rearwardly-extending tongue units being aligned respectively with said tongues of said frontwardly-extending tongue units.  
     
     
         5 . The fan unit as defined in  claim 4 , wherein said tongues are constructed as ribs.  
     
     
         6 . The fan unit as defined in  claim 1 , wherein each of said blade bodies has a cross-section that is shaped as a teardrop.