Electric motor having regenerative braking

A universal electric motor having electrical braking capability for use in machine tools, the motor comprising:

• a stator including one or more field windings;
• an armature having windings and being rotatably mounted within said stator and a commutator mounted for rotation with said armature;
• a drive circuit adapted to be powered by a power source for energizing the motor, said drive circuit including a first pair of brushes located on opposite sides of and adapted to be brought into physical contact with said commutator;
• a brake circuit connected to said armature winding and to one field winding, which when activated, is adapted to establish a regenerative current flow across said commutator and a second pair of brushes located on opposite sides of and adapted to be brought into physical contact with said commutator, said second pair of brushes being angularly displaced from said first pair of brushes around the periphery of said commutator;
• a switch mechanism operable between a first position wherein said drive circuit is energized, only said first set of brushes are in physical contact with said commutator, and said brake circuit is deactivated and a second position wherein said brake circuit is activated, only said second set of brushes is in physical contact with said commutator and said drive circuit is deenergized.

An electric motor having electrical braking capability, the motor comprising:

• a stator;
• an armature rotatably mounted within said stator;
• a commutator mounted for rotation with said armature;
• a drive circuit for energizing the motor, said drive circuit including a first pair of brushes located on opposite sides of said commutator;
• a brake circuit for regeneratively braking the motor, including a second pair of brushes located on opposite sides of said commutator;
• switching means operable between a first position wherein said drive circuit is energized, only said first set of brushes is in physical contact with said commutator, and said brake circuit is deactivated and a second position wherein said brake circuit is activated, only said second set of brushes is in physical contact with said commutator and said drive circuit is deenergized.

An electric motor having electrical braking capability, the motor comprising:

• a stator;
• an armature rotatably mounted within said stator;
• a commutator mounted for rotation with said armature;
• a drive circuit for energizing the motor, said drive circuit including a first pair of brushes located on opposite sides of said commutator and positioned at a first angle relative to an armature neutral position in a direction opposite the direction of rotation;
• a brake circuit for regeneratively braking the motor, including a second pair of brushes located on opposite sides of said commutator and positioned at a second angle relative to the armature neutral position in the direction of rotation;
• switching means movable between first and second positions wherein in said first position said drive circuit is energized, only said first set of brushes is in physical contact with said commutator, and said brake circuit is deactivated and wherein in said second position said brake circuit is activated, only said second set of brushes is in physical contact with said commutator and said drive circuit is deenergized.