D.C. electric motor

• US 4,873,463 A
• Filed: 04/16/1987
• Issued: 10/10/1989
• Est. Priority Date: 08/22/1985
• Status: Expired due to Fees

• Current Assignee: Gareth Jones
• Original Assignee: Gareth Jones
• Inventors: Jones, Gareth
• Primary Examiner(s): Salce, Patrick R.
• Assistant Examiner(s): JONES, JUDSON
• Application Number:
  US07/052,045
• Time in Patent Office: 908 Days
• Field of Search: 318/138, 318/254, 318/439, 310/46, 310/68 R, 310/68 B, 310/177, 310/179
• US Class Current: 310/68.00B
• CPC Class Codes: H02K 23/62 Motors or generators with stationary armatures and rotating excitation field
• CPC Class Codes: H02K 29/10 using light effect devices

Abstract

In a d.c. motor, the stator may form the armature and has its windings inserted in slots in its cylindrical surface and the rotor may comprise a permanent magnet or be provided with d.c. windings. Switching means operate in synchronism with rotation of the rotor to connect a d.c. source to the armature windings so that a rotating field is produced in arrears of the rotor field to exert a repelling force on the rotor poles. Because the rotor and stator fields are in opposition, rather than in mutual assistance, less energy is needed to energize the windings to produce a given torque. Also the current in each winding is very low when commutation occurs, and sparking avoided.

Claims

1. A d.c. motor which is energizable by a d.c. electrical energy source, said motor comprising:

a stator core having a cylindrical shaped inner surface;

a rotor journalled on a shaft for rotation within the cylindrical shaped inner surface of the stator core, said shaft having an axis;

armature windings inserted in slots in the stator core and being divided into similar armature coils mutually spaced about said shaft axis;

said rotor including field generating means providing magnetic rotor poles mutually spaced about the shaft axis and serving to induce an e.m.f. in each armature coil during rotation of the rotor, said rotor adapted such that the associated radial distance between each magnetic rotor pole and the inner surface of the stator core remain substantially constant as the rotor rotates; and

switching means adapted to connect said armature coils to the d.c. source so as to apply an e.m.f. to each armature coil in timed synchronism with rotation of the rotor such that (i) switching of the d.c. to an armature coil occurs when a pole generated by that coil is substantially in alignment with a magnetic rotor pole of opposite polarity, (ii) immediately before switching, the e.m.f. induced in that armature coil is approaching a maximum value and opposes the applied e.m.f., and (iii) immediately after switching, that armature pole and the magnetic rotor pole are of like polarity and the induced e.m.f. assists the applied e.m.f., said armature windings providing a rotating field which is in arrear of and opposes the rotor fields so as to exert a repelling force against the rotor poles, said switching means including a device for sensing rotor position and controlling an electronic means which switches the d.c. source to the armature windings, said electronic control means including power switching devices and means for providing a pulse train to control the power switching devices in which the mark-space ratio of the pulse train is adjustable but, for a given adjustment, is constant over the whole cycle.

2. A d.c. motor which is energizable by a d.c. electrical source, said motor comprising:

a stator having a cylindrical inner surface;

a rotor journalled on a shaft for rotation within the cylindrical inner surface of the stator, said rotor including arms radially projecting from and mutually spaced about an axis of the shaft, each arm of the rotor having an arcuate end of diameter less than the diameter of the cylindrical inner surface of the stator so that a uniform gap exists between the ends of the rotor arms and cylindrical inner surface of the stator as the rotor rotates;

armature windings inserted in slots in the cylindrical surface on the stator and being divided into similar armature coils mutually spaced about the shaft axis;

field generating means located on said rotor for providing magnetic rotor poles, each rotor arm providing an associated magnetic rotor pole and serving to induce an e.m.f. in each armature coil during rotation of the rotor;

switching means adapted to connect said armature coils to the d.c. source so as to apply an e.m.f. to each armature coil in timed synchronism with rotation of the rotor such that switching of the d.c. to each armature coil occurs when a pole generated by that coil is substantially in alignment with a rotor pole of opposite polarity and such that immediately before switching, the e.m.f. induced in that armature coil is approaching maximum value and opposes the applied e.m.f. and immediately after switching those poles are of like polarity and the induced e.m.f. assists the applied e.m.f., said armature winding providing a rotating field which is in arrear of and opposes the rotor fields so as to exert a repelling force on the rotor poles;

said switching means including a device for sensing rotor position and controlling an electronic means which switches the d.c. source to the armature windings;

said electronic control means including power switching devices and means for providing a pulse train to control the power switching devices in which the mark-space ratio of the pulse train is adjustable but, for a given adjustment, is constant over the whole cycle.

3. A d.c. motor which is energizable by a d.c. electrical energy source, said motor comprising:

a stator having a cylindrical inner surface;

a rotor journalled on a shaft for rotation about an axis of the shaft within the cylindrical inner surface of the stator, said rotor including arms radially projecting from and mutually spaced around the shaft axis, each arm having an arcuate end of diameter less than the diameter of the cylindrical inner surface of the stator, a uniform gap being present between the arcuate ends of the rotor arms and the cylindrical inner surface of the stator as the rotor rotates;

armature windings inserted in slots in the cylindrical surface of the stator and being divided into similar armature coils mutually spaced about the shaft axis;

field generating means carried by the rotor for providing magnetic rotor poles at the ends of the rotor arms, each rotor arm providing an associated magnetic rotor pole and serving to induce an e.m.f. in each armature coil during rotation of the rotor; and

switching means adapted to connect said armature windings in said slots of the stator to the d.c. source so as to apply an e.m.f. to each armature coil in timed synchronism with rotation of the rotor so as to generate a rotating field which is in arrear of and opposes the rotor fields so as to exert a repelling force against the magnetic rotor poles, said switching means being adapted such that switching of the d.c. to each armature winding occurs when a magnetic pole generated by that armature winding is substantially aligned with a magnetic rotor pole of opposite polarity and such that, immediately before switching, the e.m.f. induced in that armature winding is approaching a maximum value and opposes the applied e.m.f. and immediately after switching, those poles are of like polarity and the induced e.m.f. assists the applied e.m.f.