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Electric motors comprising rotors with oil drain Disclosure Number: IPCOM000182393D
Publication Date: 2009-Apr-29
Document File: 2 page(s) / 69K

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Electric motors comprising rotors with oil drain

In electric motors for household appliances like refrigerators and freezers there is a tendency for the lubrication oil to enter the compressor motor air gap. This is a disadvantage as it causes watt jumps and performance reduction of the system due to the viscous drag applied to the rotor.                                 

By these rotors with oil drain the lubrication oil is guided in an oil drain channel back to the oil sump in the bottom of the compressor. The channel is made by the interlocking stamping process of the laminations and packaging of the rotor core.

US 4396848 describes a method for controlling oil flow in electrical motor air gaps, rotors for such motors and methods of making the same. The rotor construction includes one or more grooves along the surface of the rotor. Grooves may be cut into rotor surfaces by a file or ball end mill.   

Following advantages are achieved by the rotors with oil drain:


  1. Especially in compressor motors with conical rotors with small air gaps it is necessary to avoid or at least to reduce oil or refrigerant in the air gap in order to minimize viscous drag applied to the rotor.
  2. Compared with cutting processes of grooves along the surface of the rotor the new idea is very beneficial as it is an integrated manufactur...