Multi-speed motor

A multi-speed, four pole, six brush, direct current electric motor comprising:

• four magnet poles disposed within a motor housing in cooperative relationship for establishing a magnetic field;
• a rotor assembly having an armature winding disposed about an axially elongated armature shaft for rotation within the magnetic field established by said magnet poles and a commutator mounted on said armature shaft and electrically connected to said armature winding, said commutator providing a commutation contact surface;
• a pair of low speed brushes wired in parallel and disposed in interfacing relationship with said rotor assembly in diametrically opposed relationship on opposite sides of said rotor assembly, each of the low speed brushes having an end face interfacing with the commutation contact surface of said commutator;
• a pair of common ground brushes wired in parallel and disposed in interfacing relationship with said rotor assembly in diametrically opposed relationship on opposite sides of said rotor assembly, the pair of common ground brushes circumferentially spaced 90 degrees from the pair of low speed brushes, each of the common ground brushes having an end face interfacing with the commutation contact surface of said commutator, each of the low speed brushes being operatively associated with a respective one of the common ground brushes to cause the motor to rotate at a first relatively low speed when an electrical current is supplied to the low speed brushes;
• and
• a pair of high speed brushes wired in parallel and disposed in interfacing relationship with said rotor assembly in diametrically opposed relationship on opposite sides of said rotor assembly, the pair of high speed brushes being disposed between the pair of low speed brushes and the pair of high speed brushes whereby each of the high speed brushes is circumferentially spaced by an acute angle from a respective one of the low speed brushes, each of the high speed brushes being operatively associated with a respective one of the common ground brushes to cause the motor to rotate at a second relatively high speed when an electrical current is supplied to the high speed brushes, each of said high speed brushes having an end face interfacing with the commutation contact surface of said commutator, the end face of each high speed brush having a first surface and a second surface intersecting at a line of intersection for contacting the commutation contact surface of said commutator, said line of intersection being displaced away from a central region of the end face of each high speed brush.

A two-speed direct current electric motor comprising:

• a pair of permanent magnet poles disposed within a motor housing in Cooperative relationship for establishing a magnetic field;
• a rotor assembly having an armature winding disposed about an axially elongated armature shaft for rotation within the magnetic field established by said magnet poles and a commutator mounted on said armature shaft and electrically connected to said armature winding, said commutator providing a commutation contact surface;
• a low speed brush disposed in interfacing relationship with said rotor assembly and having an end face interfacing with the commutation contact surface of said commutator;
• a common ground brush disposed in interfacing relationship with said motor assembly and having an end face interfacing with the commutation contact surface of said commutator, said low speed brush and said common ground brush operatively associated to cause the motor to rotate at a first relatively low speed when an electrical current is supplied to said low speed brush;
• and
• a high speed brush disposed in interfacing relationship with said rotor assembly and in spaced relationship with and between said low speed brush and said common ground brush, said high speed brush and said common ground brush operatively associated to cause the motor to rotate at a second relatively high speed when an electrical current is supplied to said high speed brush, said high speed brush having an end face interfacing with the commutation contact surface of said commutator, the end face of said high speed brush having a first surface and a second surface intersecting at a line of intersection for contacting the commutation contact surface of said commutator, said line of intersection being displaced away from a central region of the end face of said high speed brush.