Electric motor having improved operating characteristics

• US 4,409,505 A
• Filed: 05/15/1981
• Issued: 10/11/1983
• Est. Priority Date: 05/15/1981
• Status: Expired due to Fees

• Current Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Petersen, Christian C.
• Primary Examiner(s): Gonzales, John
• Application Number:
  US06/263,975
• Time in Patent Office: 879 Days
• Field of Search: 310/40 MM, 310/90, 310/228, 310/248, 310/251, 308/238, 308/241, 308/DIG. 7
• US Class Current: 310/90
• CPC Class Codes: H02K 13/10 Arrangements of brushes or commutators specially adapted for improving commutation
• CPC Class Codes: H02K 5/1672 radially supporting the rotary shaft at both ends of the rotor H02K5/1677 takes precedence

Abstract

An economical, miniature electric motor exhibiting improved efficiency and in-specification, first-use performance after substantial periods of non-use, which is especially suited for operating the film eject mechanism of a self-developing camera, includes single piece, base metal brushes, a plain bore armature bearing in the commutator end cap, and a fibrous wicking material containing a supply of commutation enhancing lubricant bearing against the commutator to provide a supply of the lubricant thereto which minimizes brush friction while enhancing electrical conduction therebetween. Additionally, migration of the commutator lubricant along the rotor shaft into the plain bore journal in the motor end cap is encouraged to provide a supply of surface lubricant for the journal.

Claims

1. An electric motor comprising in combination:

a housing including means for establishing a stator field;

an armature including a commutator and a rotor shaft;

bearing means supporting said rotor shaft for rotation with respect to said stator;

a brush arrangement comprising at least one brush including a terminal portion integrally formed of base metal resiliently biased into contact with said commutator; and

means for providing a supply of synthetic non-organic commutator enhancing lubricant to the area of or adjoining said commutator to enhance commutation with said brush arrangement and thereby reduce the voltage drop from said terminal portion to said commutator.

2. The electric motor of claim 1 wherein said bearing means includes a plain bore journal defined by a sleeve bearing mounted in said housing adjacent said commutator, and said lubricant comprises a material having physical characteristics providing migration of said lubricant between said sleeve bearing and said commutator.

3. The electric motor of claim 2 wherein said sleeve bearing includes an entry chamber facing in the direction of said commutator to facilitate migration of said lubricant into said sleeve bearing.

4. An electric motor comprising in combination:

a housing including stator means for establishing a stator field;

a rotor including a rotor shaft carrying an armature and a commutator, said armature including an armature coil connected to said commutator;

bearing means for supporting said rotor shaft for rotation including a plain bore journal located adjacent said commutator;

a brush arrangement secured to said stator means and including at least two brushes resiliently biased into contact with said commutator; and

means for providing a supply of synthetic, non-organic commutator enhancing lubricant to said motor at a point at least in adjoining relation to said commutator to enhance commutation and for causing said lubricant to migrate from said commutator along said rotor shaft toward and into said plain bore journal to lubricate said journal.

5. The electric motor of claim 4 wherein said plain bore journal is defined by a sleeve bearing mounted in said housing, said sleeve bearing including an entry chamber facing in the direction of the migrating commutation enhancing lubricant to facilitate migration thereof into said sleeve bearing.

6. An improved electric motor for driving the film unit eject mechanism of a self-developing photographic camera, the mechanism being of the type having a step-down gear train connected to pressure applying rollers between and through which an exposed film unit passes during ejection from the camera, said improved electric motor comprising:

stator means for establishing a stator field;

a rotor including a rotor shaft for connection to the film eject mechanism gear train, an armature and a commutator mounted on said rotor shaft, said armature including an armature coil connected to said commutator;

bearing means for supporting said rotor shaft for rotation including a plain bore journal located adjacent said commutator;

a brush arrangement comprising a pair of brushes including terminal portions integrally formed of base metal resiliently biased into contact with said commutator; and

means for dispensing a synthetic, non-organic lubricant onto said commutator to enhance commutation thereby reducing the voltage drop from said terminal portion to said commutator and for causing said lubricant to migrate from said commutator along said rotor shaft toward and into said plain bore journal to lubricate said journal.