Belt drive system with outer rotor motor

• US 20060232147A1
• Filed: 05/18/2006
• Published: 10/19/2006
• Est. Priority Date: 10/07/2003
• Status: Active Grant

• Current Assignee: Wei Cheng
• Original Assignee: Wei Cheng
• Inventors: Cheng, Wei
• Granted Patent: US 7,362,016 B2
• Time in Patent Office: Days
• US Class Current: 310/52
• CPC Class Codes: A63B 22/02 with movable endless bands , e.g. treadmills other training appliances for running on the spot A63B69/0028
• CPC Class Codes: A63B 22/0235 driven by a motor
• CPC Class Codes: A63B 22/0242 with speed variation
• CPC Class Codes: A63B 22/025 electrically, e.g. D.C. motors with variable speed control
• CPC Class Codes: A63B 2220/34 Angular speed
• CPC Class Codes: A63B 2225/30 Maintenance
• CPC Class Codes: H02K 11/225 Detecting coils
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 2211/03 Machines characterised by circuit boards, e.g. pcb
• CPC Class Codes: H02K 5/00 Casings; Enclosures; Supports
• CPC Class Codes: H02K 5/225 Terminal boxes or connection arrangements specially adapted for submersible motors H02K5/132
• CPC Class Codes: H02K 7/088 radially supporting the rotor directly
• CPC Class Codes: H02K 7/1016 Machine of the outer rotor type
• CPC Class Codes: H02K 9/06 with fans or impellers driven by the machine shaft

Abstract

An outer rotor motor comprises a tubular shaft for maximum motor cooling effect. Coolant may flow through coolant channels of the shaft and the motor in various configurations to carry away the heat. A thermally conductive component may be inserted into the hollow shaft under the stator section to optimize the airflow and cooling. Physical construction of the motor and control algorithms may further enhance motor performance with appropriate sensors. A compact, smooth, and cool operating motor may thus be achieved for applications such as treadmills or other belt drive systems.

Claims

1. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a heat transfer coolant,

iii) a stator shaft extending through said rotor and fixed to said frame structure, wherein at least a portion of said shaft is configured with a coolant channel adapted to permit said coolant to flow along said coolant channel effective to provide convective cooling of said motor,

iv) a stator configured with a plurality of slots fixed to said stator shaft and forming an air gap with said poles,

v) a plurality of stator windings wound through said slots, and

vi) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft; and

g) a motor controller operatively connected to said control system for controlling the speed of said motor.

2. The treadmill of claim 1 wherein said coolant channel extends substantially through the length of said stator shaft.

3. The treadmill of claim 1 wherein said coolant channel is concentric with said stator shaft and has a generally circular cross section.

4. The treadmill of claim 1 wherein said coolant channel extends through at least a portion of said stator shaft and said stator shaft additionally includes a plurality of apertures extending from said coolant channel to the outer surface of said stator shaft effective to permit at least portion of said coolant to flow from said coolant channel through said air gap.

5. The treadmill of claim 1 wherein said coolant channel extends through at least a portion of said stator shaft and a thermally conductive member is located within said coolant channel.

6. The treadmill of claim 5 wherein said thermally conductive member is configured so as to permit at least a portion of said coolant to flow through said thermally conductive member.

7. The treadmill of claim 6 wherein said thermally conductive member includes surface areas in contact with said coolant that are greater than the corresponding surface area of said coolant channel where said conductive member is located.

8. The treadmill of claim 5 wherein said thermally conductive member includes a plurality of fins extending longitudinally along said coolant channel that form said surface areas.

9. The treadmill of claim 1 wherein said motor includes at least one end cap which is configured with at least one aperture to permit said coolant to flow out of said rotor.

10. The treadmill of claim 1 wherein said motor includes at least one end cap which is sealed against air flow through said end cap.

11. The treadmill of claim 1 wherein said stator is configured with a plurality of stator coolant channels so as to permit at least a portion of said coolant to flow through said stator.

12. The treadmill of claim 1 wherein said coolant channel is configured in the outer surface of said stator shaft.

13. The treadmill of claim 1 wherein said coolant is a gas.

14. The treadmill of claim 13 wherein said gas is air.

15. The treadmill of claim 1 wherein said coolant is a liquid.

16. The treadmill of claim 1 additionally including a coolant transfer mechanism connected to said stator shaft for transferring said coolant through said coolant channel.

17. The treadmill of claim 16 wherein said coolant is gas and said transfer mechanism includes a fan or a blower.

18. The treadmill of claim 16 wherein said coolant is a liquid and said transfer mechanism includes a pump.

19. The treadmill of claim 16 wherein said transfer mechanism includes a filter for filtering said coolant.

20. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a stator shaft fixed to said frame structure,

iii) a heat transfer coolant,

iv) a coolant transfer mechanism for transferring said coolant through at least a portion of said motor, wherein the operation of said mechanism is independent of the rate of rotation of said motor,

v) a stator configured with a plurality of slots fixed to said stator shaft,

vi) a plurality of stator windings wound through said slots, and

vii) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft, and

g) a motor controller operatively connected to said control system for controlling the speed of said motor.

21. The treadmill of claim 20 wherein said transfer mechanism includes a fan operatively connected to said control system or said motor controller and is effective to transfer at least a portion of said coolant through said air gap.

22. The treadmill of claim 21 wherein said motor includes at least one end cap that is configured to include a set of apertures and wherein said transfer mechanism is effective to transfer at least a portion of said coolant through said set of apertures.

23. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to generate a speed command signal for controlling the speed of said belt to a desired speed; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a stator shaft fixed to said frame structure,

iii) a stator configured with a plurality of slots fixed to said stator shaft,

iv) a plurality of stator windings wound through said slots,

v) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft, and

vi) a high resolution sensing mechanism operatively connected to said rotor for generating a rotor position information signal,

g) a motor controller operatively connected to said control system and said sensing mechanism responsive to said speed command signal in combination with said rotor speed, and position signals to apply power to said stator windings for controlling the speed of said motor to achieve said desired belt speed.

24. The treadmill of claim 23 wherein said sensing mechanism includes an optical encoder.

25. The treadmill of claim 23 wherein said sensing mechanism includes a resolver.

26. The treadmill of claim 25 wherein said resolver includes a resolver rotor secured for rotation with said rotor and a resolver stator secured to said stator shaft.

27. The treadmill of claim 23 wherein said treadmill does not include a hall effect sensor.

28. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a stator shaft fixed to said frame structure,

iii) a stator configured with a plurality of slots fixed to said stator shaft and forming an air gap with said poles,

iv) a plurality of stator windings wound through said slots,

v) wherein said motor is configured to minimize cogging torque wherein said configuration is selected from the group consisting of said stator windings having a fractional pitch, said stator slots orientated in a skewed relationship with said the edges of said permanent magnets, and said magnets are shaped so as to result in a substantially sinusoidally distributed magnetic flux in said air gap, and

vi) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft; and

g) a motor controller operatively connected to said control system for controlling the speed of said motor.

29. The treadmill of claim 28 including both said stator windings having fractional pitch and said stator slots orientated in a skewed relationship with said edges of said permanent magnets.

30. The treadmill of claim 29 additionally including said magnet shaping.

31. The treadmill of claim 29 including both said stator windings having fractional pitch and said magnet shaping.

32. The treadmill of claim 28 including both said stator slots orientated in a skewed relationship with said edges of said permanent magnets and said magnet shaping.

33. The treadmill of claim 28 for wherein there are 21 of said stator slots and 8 or 16 of said poles.

34. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other, said first pulley is rotatably secured to a rearward portion of said frame structure;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a stator shaft extending through said rotor,

iii) a stator configured with a plurality of slots fixed to said stator shaft and forming an air gap with said poles,

iv) a plurality of stator windings wound through said slots, and

v) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft; and

g) a motor controller operatively connected to said control system for controlling the speed of said motor.

35. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a stator shaft extending through said rotor

iii) a stator configured with a plurality of slots fixed to said stator shaft and forming an air gap with said poles,

iv) a plurality of stator windings wound through said slots, and

v) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft; and

g) at least one clamping mechanism including a resilient material for clamping said stator shaft to said frame structure wherein said resilient material is effective to insulate said frame structure from vibrations generated by said motor.

h) a motor controller operatively connected to said control system for controlling the speed of said motor.

36. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a stator shaft extending through said rotor

iii) a stator configured with a plurality of slots fixed to said stator shaft and forming an air gap with said poles,

iv) a plurality of stator windings wound through said slots, and

v) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft; and

g) at least one clamping mechanism including a thermal insulation material for clamping said stator shaft to said frame structure wherein said thermal insulation material is effective to insulate said frame structure from the heat generated by said motor.

h) a motor controller operatively connected to said control system for controlling the speed of said motor.

37. An exercise treadmill, comprising:

a) a first and a second frame structure, wherein said first and said second frame structure each is configured with at least one aperture;

b) a first and a second pulley, said pulleys rotatably secured to said frame structures and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a heat transfer coolant,

iii) a stator shaft extending through said rotor and fixed at each end to said first and said second frame structures respectively, wherein at least a portion of said shaft is configured with a coolant channel adapted to permit said coolant to flow along said coolant channel and through said apertures in said frame structures effective to provide convective cooling of said motor,

iv) a stator configured with a plurality of slots fixed to said stator shaft and forming an air gap with said poles,

v) a plurality of stator windings wound through said slots, and

vi) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft; and

g) a motor controller operatively connected to said control system for controlling the speed of said motor.

38. The treadmill of claim 37 wherein said motor controller is secured within said first frame structure.

39. An exercise treadmill, comprising:

a) a frame structure;

b) a first and a second pulley, said pulleys rotatably secured to said frame structure and positioned substantially parallel to each other;

c) a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

d) a control system;

e) a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a set of user controls effective to permit a user to control the speed of said belt; and

f) a motor, integral with and for rotating said first pulley wherein said motor includes;

i) a rotor having a housing that forms a generally cylindrical outer surface for said first pulley and includes a plurality of permanent magnets forming a set of poles secured to and spaced about the inner circumference of said housing,

ii) a heat transfer coolant,

iii) a stator shaft extending through said rotor and fixed to said frame structure, wherein at least a portion of said shaft is configured with a coolant channel adapted to permit said coolant to flow along said coolant channel effective to provide convective cooling of said motor,

iv) a stator configured with a plurality of slots fixed to said stator shaft and forming an air gap with said poles,

v) a plurality of stator windings wound through said slots, and

vi) at least one bearing secured between said stator shaft and said rotor for permitting said rotor to rotate with respect to said stator shaft; and

g) a motor controller operatively connected to said control system for having field orientation control algorithms to control the speed of said motor.