Motorized blower assemblies, and methods of making same

Abstract

A motorized blower assembly ( 1 ) is provided for use in respiratory therapy applications. The active motor sub-assemblies ( 6, 7, 9 ) are encapsulated within an over-molded thermoplastic material ( 5 ) with selected vibration-dissipative and thermally-conductive properties. The resulting blower assembly operates at reduced sound levels of 1.0-3.0 dB, and with an increased efficiency of 3-9% over currently-marketed blowers of similar size and air flow capability.

What is claimed is: 
     
         1 . A motorized blower assembly, comprising:
 a housing having an air flow passageway extending between an inlet and an outlet;   a motor stator assembly positioned within and secured to said housing; a bearing assembly mounted on said housing in a predetermined position relative to said motor stator assembly;   a rotor assembly having a shaft, an impeller mounted on one marginal end portion of said shaft, and a magnet mounted on an intermediate portion of said shaft;   wherein another marginal end portion of said shaft is received in said bearing assembly; and   an over-molded material engaging said housing and encapsulating said motor stator assembly.   
     
     
         2 . A motorized blower assembly as set forth in  claim 1  wherein said over-molded material is a thermoplastic elastomer. 
     
     
         3 . A motorized blower assembly as set forth in  claim 1  wherein said over-molded material has a predetermined coefficient of thermal expansion. 
     
     
         4 . A motorized blower assembly as set forth in  claim 1  wherein said over-molded material has a predetermined coefficient of thermal conductivity. 
     
     
         5 . A motorized blower assembly as set forth in  claim 1  wherein said over-molded material has predetermined vibration dissipative properties to reduce the vibration generated by said blower assembly. 
     
     
         6 . A motorized blower assembly as set forth in  claim 1  wherein said housing includes an upper housing part and a lower housing part, and further comprising a gasket positioned between said housing parts. 
     
     
         7 . A motorized blower assembly as set forth in  claim 1  wherein said motor stator assembly includes electrical terminals, and wherein said terminals are partially encapsulated by said molded material. 
     
     
         8 . A motorized blower assembly as set forth in  claim 1  wherein said over-molded material is injection molded into said housing. 
     
     
         9 . The method of manufacturing a portion of a motorized blower assembly, comprising the steps of:
 providing a first die having complementary die halves defining a first housing part cavity therewithin;   injecting a material into said first die cavity to form a first housing part;   opening said first die by moving said first die halves apart;   removing said first housing part from such opened first die;   providing a second die having complementary die halves defining a stator assembly cavity therewithin;   opening said second die by moving said second die halves away from one another;   placing said first housing part into the cavity of one of said second die halves;   providing a stator assembly and a bearing assembly;   placing said stator assembly and said bearing assembly in the other of said second die halves;   closing said second die by moving said second die halves toward one another to accurately position said housing first part, said stator assembly and said bearing assembly relative to one another, and to define a second mold cavity therebetween;   injecting a thermoplastic material into said second mold cavity to over-mold said stator assembly and said bearing assemblies within said first housing part;   opening said second die by moving said second mold halves away from one another; and   removing said first housing part and said over-molded stator and bearing assemblies;   thereby to manufacture a portion of a motorized blower assembly.   
     
     
         10 . The method as set forth in  claim 9  and further comprising the additional steps of:
 providing a second housing part; and 
 joining said second housing part to said first housing part to provide a motorized blower assembly having an air flow passageway extending between an inlet and an outlet. 
 
     
     
         11 . The method as set forth in  claim 9  wherein said first housing part, said stator assembly and said bearing assembly are positioned in said second mold to an accuracy of about ±0.0005 inches.