Centrifugal Fan

Abstract

A centrifugal fan 1 as an example of the invention includes: an impeller 2 having a cylindrical outline shape with an outer peripheral diameter of 25 mm or less; a motor 3 rotating the impeller 2; and a housing 4 accommodating the impeller 2 therein. The motor 3 is a three phase motor and rotates the impeller 2 around the central axis 10 thereof at 10000 or more revolutions per minute. Since the motor 3 is a three phase motor, an utilization efficiency of coils is higher, which decrease a heat generation of a stator 38. Besides, the motor 3 is driven so that three coils are power supplied at all times, thereby further decreasing a heat generation of the stator 38.

1 . A centrifugal fan comprising: 
 an impeller having a cylindrical outline shape;    a motor connected to the impeller and rotating the impeller at 10000 or more revolutions per minute around a central axis thereof; and    a housing accommodating the impeller therein,    wherein the motor includes: 
 a rotor assembly supporting the impeller and having a rotor magnet disposed around the central axis thereof; and  
 a stationary assembly having a stator generating a rotational torque between the rotor magnet and the stator,  
   wherein the impeller includes plural vanes, each vane has a connection end at a lower and an upper end, and is disposed at an equal interval each other as a manner that the connection end is fixed on an upper surface of the rotor assembly, that each vane is disposed parallel to the central axis having a predetermined distance from the central axis in radial direction, and that the upper end of each vane is fixed on a ring as an open end, and the outline shape of the impeller satisfies relations of 2≦h/r≦20 and 2r≦25 mm, where r is a radius of the impeller and h is a height of the impeller in axial direction, and    wherein the housing includes: 
 an intake port formed on the open end of the impeller, from which an air is absorbed into the impeller when the impeller rotates; and  
 an air blowing-out port formed on the housing, from which the air is flowing out to an outside of the centrifugal fan when the impeller rotates.  
   
   
   
       2 . The centrifugal fan according to  claim 1 , wherein electric currents are supplied at all times in all stator coils wound around the stator as a three phase motor.  
   
   
       3 . The centrifugal fan according to  claim 1 , wherein the rotor magnet is a rare earth bond magnet.  
   
   
       4 . The centrifugal fan according to  claim 2 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal base plate with which the electronic component is in contact.    
   
   
       5 . The centrifugal fan according to  claim 4 , wherein the stationary assembly is provided with a radiation fin attached to the base plate for radiating heat.  
   
   
       6 . The centrifugal fan according to  claim 2 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal base plate located at a bottom of the centrifugal fan, the metal base plate being in contact with a member and the member being in contact with the electronic component.    
   
   
       7 . The centrifugal fan according to  claim 6 , wherein the stationary assembly is provided with a radiation fin attached to the base plate for radiating heat.  
   
   
       8 . The centrifugal fan according to  claim 2 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal part made of a metal formed in at least a part of the housing,    wherein the electronic component is in contact with at least a part of the metal part of the housing.    
   
   
       9 . The centrifugal fan according to  claim 2 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal part made of a metal formed in at least a part of the housing,    wherein the electronic component is in contact with a member and the member is in contact with at least a part of the metal part of the housing.    
   
   
       10 . The centrifugal fan according to  claim 2 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal part made of a metal formed at a part of the housing,    wherein the metal part is disposed in an area in which the plural vanes are arranged in the housing in the axial direction and    the electronic component is in contact with the outer surface of the metal part.    
   
   
       11 . The centrifugal fan according to  claim 2 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal part made of a metal formed at a part of the housing,    wherein the metal part is disposed in an area in which the plural vanes are arranged in the housing in the axial direction and    the electronic component is in contact with a member and the member is in contact with at least a part of the metal part of the housing.    
   
   
       12 . The centrifugal fan according to  claim 1 , wherein the central axis of the three phase motor coincides with a central axis of the impeller and an outer peripheral diameter of the three phase motor is smaller than that of the impeller.  
   
   
       13 . A centrifugal fan comprising: 
 an impeller having a cylindrical outline shape;    a three phase motor connected to the impeller and rotating the impeller at 10000 or more revolutions per minute around a central axis thereof; and    a housing accommodating the impeller therein,    wherein the motor includes: 
 a rotor assembly supporting the impeller and having a rotor magnet disposed around the central axis thereof; and  
 a stationary assembly having a stator generating a rotational torque between the rotor magnet and the stator,  
   wherein the impeller includes plural vanes, each vane has a connection end at a lower and an upper end, and is disposed at an equal interval each other as a manner that the connection end is fixed on an upper surface of the rotor assembly, that each vane is disposed parallel to the central axis having a predetermined distance from the central axis in radial direction, and that the upper end of each vane is fixed on a ring as an open end, and the outline shape of the impeller satisfies a relation of 2r≦25 mm, where r is a radius of the impeller, and    wherein the housing includes: 
 an intake port formed on the open end of the impeller, from which an air is absorbed into the impeller when the impeller rotates; and  
 an air blowing-out port formed on the housing, from which the air is flowing out to an outside of the centrifugal fan when the impeller rotates.  
   
   
   
       14 . The centrifugal fan according to  claim 13 , wherein electric currents are supplied at all times in all stator coils wound around the stator as a three phase motor.  
   
   
       15 . The centrifugal fan according to  claim 14 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal base plate with which the electronic component is in contact.    
   
   
       16 . The centrifugal fan according to  claim 15 , wherein the stationary assembly is provided with a radiation fin attached to the base plate for radiating heat.  
   
   
       17 . The centrifugal fan according to  claim 14 , wherein the stationary assembly further includes: 
 a printed circuit board attached on the stationary assembly;    an electronic component having a driving circuit for the three phase motor and mounted on the printed circuit board; and    a metal base plate located at a bottom of the centrifugal fan, the metal base plate being in contact with a member and the member being in contact with the electronic component.    
   
   
       18 . The centrifugal fan according to  claim 17 , wherein the stationary assembly is provided with a radiation fin attached to the base plate for radiating heat.  
   
   
       19 . The centrifugal fan according to  claim 13 , wherein the rotor magnet is a rare earth bond magnet.  
   
   
       20 . The centrifugal fan according to  claim 13 , wherein the central axis of the three phase motor coincides with a central axis of the impeller and an outer peripheral diameter of the three phase motor is smaller than that of the impeller.