Low-voltage direct current motor

Abstract

A low-voltage direct current motor has a stator and a rotor rotatable relative to the stator. The rotor includes a rotary shaft, a rotor core fixed to the shaft, a commutator fixed to the shaft adjacent to the rotor core, and rotor windings wound about poles of the rotor core and electrically connected to the commutator. The stator includes a round housing, a permanent magnet mounted to an inner surface of the housing, and brushes disposed in sliding contact with the commutator. An input voltage of the motor is in the range of 7 to 36V, and a ratio of an outer diameter of the rotor core to an outer diameter of the housing is in the range of 67% to 75%.

1 . A brush roller for a vacuum cleaner, the brush roller being driven by a low-voltage direct current motor, the low-voltage direct current motor comprising:
 a stator comprising a round housing, a permanent magnet mounted to an inner surface of the housing, and brushes; and   a rotor rotatable relative to the stator, the rotor comprising a shaft, a rotor core fixed to the shaft, a commutator fixed to the shaft adjacent to the rotor core, and rotor windings wound about poles of the rotor core and electrically connected to the commutator,   wherein the brushes of the stator are disposed in sliding contact with the commutator, an input voltage of the motor is in the range of 7 to 36V, and a ratio of an outer diameter of the rotor core to an outer diameter of the housing is in the range of 67% to 75%, and wherein the rotor core has five or ten poles, the stator has two permanent magnetic poles, and the commutator has five commutator segments.   
     
     
         2 . The brush roller of  claim 1 , wherein the permanent magnet is a ferrite magnet made of a material with a maximum energy product BHmax of 35.8±1.6 kj/m 3  or 34.2±1.6 kj/m 3 . 
     
     
         3 . The brush roller of  claim 1 , wherein the ratio of the outer diameter of the rotor core to the outer diameter of the housing is in the range of 67.6% to 73.8%. 
     
     
         4 . The brush roller of  claim 1 , wherein a wire diameter of the rotor windings of the motor is in the range of 0.1 mm to 0.5 mm. 
     
     
         5 . The brush roller of  claim 1 , wherein a wire diameter of the rotor windings of the motor is in the range of 0.3 mm to 0.35 mm. 
     
     
         6 . The brush roller of  claim 1 , wherein the outer diameter of the housing is 27.5 mm±0.3 mm, and the outer diameter of the rotor core is 19 mm±0.2 mm. 
     
     
         7 . The brush roller of  claim 1 , wherein when an axial length of the magnet is 21.0 mm±2.1 mm, 27.5 mm±0.3 mm, or 34 mm±0.3 mm, the motor is capable of achieving a rated power output of 20 W, 50 W, or 80 W, respectively. 
     
     
         8 . A brush roller for a vacuum cleaner, the brush roller being driven by a low-voltage direct current motor, the low-voltage direct current motor comprising:
 a stator comprising a round housing, a permanent magnet mounted to an inner surface of the housing, and brushes; and   a rotor rotatable relative to the stator, the rotor comprising a shaft, a rotor core fixed to the shaft, a commutator fixed to the shaft adjacent to the rotor core, and rotor windings wound about poles of the rotor core and electrically connected to the commutator,   wherein the brushes of the stator are disposed in sliding contact with the commutator, an input voltage of the motor is in the range of 7 to 36V, and a ratio of an outer diameter of the rotor core to an outer diameter of the housing is in the range of 67% to 75%, wherein a wire diameter of the rotor windings of the motor is in the range of 0.1 mm to 0.5 mm.   
     
     
         9 . The brush roller of  claim 8 , wherein the permanent magnet is a ferrite magnet made of a material with a maximum energy product BHmax of 35.8±1.6 kj/m 3  or 34.2±1.6 kj/m 3 . 
     
     
         10 . The brush roller of  claim 9 , wherein the rotor core has five or ten poles, the stator has two permanent magnetic poles, and the commutator has five commutator segments. 
     
     
         11 . The brush roller of  claim 9 , wherein the outer diameter of the housing is 27.5 mm±0.3 mm, and the outer diameter of the rotor core is 19 mm±0.2 mm. 
     
     
         12 . The brush roller of  claim 8 , wherein the outer diameter of the housing is 27.5 mm±0.3 mm, and the outer diameter of the rotor core is 19 mm±0.2 mm. 
     
     
         13 . The brush roller of  claim 8 , wherein when an axial length of the magnet is 21.0 mm±2.1 mm, 27.5 mm±0.3 mm, or 34 mm±0.3 mm, the motor is capable of achieving a rated power output of 20 W, 50 W, or 80 W, respectively 
     
     
         14 . The brush roller of  claim 8 , wherein a wire diameter of the rotor windings of the motor is in the range of 0.3 mm to 0.35 mm. 
     
     
         15 . A brush roller for a vacuum cleaner, the brush roller being driven by a low-voltage direct current motor, the low-voltage direct current motor comprising:
 a stator comprising a round housing, a permanent magnet mounted to an inner surface of the housing, and brushes; and   a rotor rotatable relative to the stator, the rotor comprising a shaft, a rotor core fixed to the shaft, a commutator fixed to the shaft adjacent to the rotor core, and rotor windings wound about poles of the rotor core and electrically connected to the commutator,   wherein the brushes of the stator are disposed in sliding contact with the commutator, an input voltage of the motor is in the range of 7 to 36V, and a ratio of an outer diameter of the rotor core to an outer diameter of the housing is in the range of 67% to 75%, wherein when an axial length of the magnet is 21.0 mm±2.1 mm, 27.5 mm±0.3 mm, or 34 mm±0.3 mm, the motor is capable of achieving a rated power output of 20 W, 50 W, or 80 W, respectively.   
     
     
         16 . The brush roller of  claim 15 , wherein the input voltage of the motor is 16.2V±1.6V. 
     
     
         17 . The brush roller of  claim 16 , wherein the permanent magnet is a ferrite magnet made of a material with a maximum energy product BHmax of 35.8±1.6 kj/m 3  or 34.2±1.6 kj/m 3 . 
     
     
         18 . The brush roller of  claim 15 , wherein the permanent magnet is a ferrite magnet made of a material with a maximum energy product BHmax of 35.8±1.6 kj/m 3  or 34.2±1.6 kj/m 3 .