Blower

Abstract

A blower for use with a hand dryer and the like has a motor; an impeller driven by the motor; a diffuser for directing air from the impeller; and a housing accommodating the motor, the impeller and the diffuser. The motor has a rotor and a stator. The rotor has a shaft, a rotor core fixed to the shaft, a ring magnet fixed to the rotor core, and a protective sleeve surrounding the ring magnet.

1 . A blower comprising: a motor with a rotor and a stator; an impeller driven by the motor; a diffuser for directing air from the impeller; and a housing accommodating the motor, the impeller and the diffuser and having an air inlet and an air outlet, wherein the rotor comprises: a shaft, a rotor core fixed to the shaft, a ring magnet fixed to the rotor core, and a protective sleeve tightly surrounding the ring magnet. 
     
     
         2 . The blower of  claim 1 , wherein the protective sleeve is made of metal. 
     
     
         3 . The blower of  claim 2 , wherein the protective sleeve is made of stainless steel plate. 
     
     
         4 . The blower of  claim 1 , wherein thickness of the protective sleeve is between 0.1 mm and 0.3 mm. 
     
     
         5 . The blower of  claim 1 , wherein the ring magnet is a bonded NdFeB rare earth ring magnet. 
     
     
         6 . The blower of  claim 1 , wherein the ring magnet is a sintered NdFeB rare earth ring magnet. 
     
     
         7 . The blower of  claim 1 , wherein the rotor has a pair of balance rings that press against the axial ends of the ring magnet to prevent axial movement of the ring magnet with respect to the rotor core. 
     
     
         8 . The blower of  claim 7 , wherein the ring magnet has an axial length that is longer than the axial length of the rotor core and each of the balance rings has a boss that locates within the respective axial end of the ring magnet. 
     
     
         9 . The blower of  claim 1 , wherein the ring magnet is keyed to the rotor core by a tongue in groove connection to prevent rotation of the ring magnet about the rotor core. 
     
     
         10 . The blower of  claim 1 , wherein the diffuser is disposed between the impeller and the motor for directing air from the impeller to the motor via a plurality of air passages and wherein the diffuser supports a bearing for the shaft. 
     
     
         11 . The blower of  claim 1 , wherein the rotor is configured to rotate at a speed greater than 25,000 rpm, preferably greater than 40,000 rpm.