Belt drive system with outer rotor motor

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.

1 . A direct drive outer rotor motor comprising: 
 a) a rotor with magnets secured inside a housing; the rotor surrounding a stator with an air gap between the rotor and stator;    b) a stator shaft for allowing a coolant to pass through said stator shaft by flow in from one side of said stator shaft, and out from the other side of said stator shaft wherein at least a portion of said stator shaft is configured with a coolant channel adapted to permit said to coolant flow;    c) a stator mounted inside the rotor on said stator shaft;    d) at least one bearing secured to said stator shaft and said rotor directly or through an end-cap mechanism for permitting said rotor to rotate with respect to said stator shaft; and    e) whereby heat is allowed to be carried away by said coolant that passes through said stator shaft, or said air gap, or both.    
   
   
       2 . The direct drive outer rotor motor of  claim 1  further comprising: said stator shaft having holes configured through the wall of said stator shaft thereby allowing said coolant to pass through said air gap between said rotor and said stator.  
   
   
       3 . The direct drive outer rotor motor of  claim 1  further comprising: a thermally conductive rod located within said shaft.  
   
   
       4 . The direct drive outer rotor motor of  claim 3  further comprising: said thermally conductive rod having fins.  
   
   
       5 . The direct drive outer rotor motor of  claim 1  further comprising: at least one of said end caps having a through hole for the passage of coolant.  
   
   
       6 . The direct drive outer rotor motor of  claim 5  further comprising: said end cap through hole being shaped and arranged to induce coolant flow.  
   
   
       7 . The direct drive outer rotor motor of  claim 1  further comprising: a fan-type device secured to one of said rotor or said end cap to induce coolant flow.  
   
   
       8 . The direct drive outer rotor motor of  claim 1  further comprising: said motor being sealed wherein said end caps do not have through holes and through holes in the wall of the shaft are sealed.  
   
   
       9 . The direct drive outer rotor motor of  claim 1  further comprising: said stator having a plurality of through-holes through a core of said stator.  
   
   
       10 . The direct drive outer rotor motor of  claim 1  wherein said motor is constructed by using a fractional pitch winding configuration in order to minimize motor cogging torque.  
   
   
       11 . The direct drive outer rotor motor of  claim 10  further comprising: said motor being constructed with skewed magnets or stator slots in order to minimize motor cogging torque.  
   
   
       12 . The direct drive outer rotor motor of  claim 1  further comprising: said motor being constructed with skewed magnets or stator slots in order to minimize motor cogging torque.  
   
   
       13 . The direct drive outer rotor motor of  claim 10  further comprising: the motor being constructed with shaped magnets in order to minimize motor cogging torque.  
   
   
       14 . The direct drive outer rotor motor of  claim 11  further comprising: the motor being constructed with shaped magnets in order to minimize motor cogging torque.  
   
   
       15 . The direct drive outer rotor motor of  claim 1  further comprising: the motor being constructed with shaped magnets in order to minimize motor cogging torque.  
   
   
       16 . A belt driving system, comprising: 
 a) a frame structure;    b) a first pulley and at least one other 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 rotatably move when said first pulley is rotated;    d) said first pulley having a motor integral therewith for rotating said first pulley, wherein the motor includes: 
 i) a rotor with magnets secured inside a housing; the rotor surrounding a stator with an air gap between the rotor and stator;  
 ii) a stator shaft for allowing a coolant to pass through said stator shaft by flow in from one side of said stator shaft, and out from the other side of said stator shaft wherein at least a portion of said stator shaft is configured with a coolant channel adapted to permit a coolant flow;  
 iii) a stator mounted inside the rotor on said stator shaft; and  
 vi) at least one bearing secured to said stator shaft and said rotor directly or through an end-cap mechanism for permitting said rotor to rotate with respect to said stator shaft; and  
   e) a motor controller operably attached to said motor.    
   
   
       17 . The belt driving system of  claim 16  further comprising said motor controller having field orientation control algorithms for said motor.  
   
   
       18 . The belt driving system of  claim 16  wherein said motor further comprises; 
 a) an encoder having a rotating disk and a sensing device,    b) said encoder being attached to said motor and used to provide accurate rotor position and speed information;    c) said disk being secured to an end cap or to the inside of said rotor so as to rotate with said rotor; and    d) said sensing device being secured to said shaft and thereby remaining stationary during motor operation.    
   
   
       19 . The belt driving system of  claim 16  wherein said motor further comprises; 
 a) a resolver having a rotor and a stator,    b) said resolver being attached to said motor and used to provide accurate rotor position information;    c) said rotor of said resolver being secured to the inside of said motor rotor so as to rotate with said motor rotor; and    d) said stator of said resolver being secured to said motor shaft and thereby remaining stationary during motor operation.    
   
   
       20 . The belt driving system of  claim 16  further comprising a cooling fan or pump secured at one end of said shaft and used to induce coolant to move through said coolant channel.  
   
   
       21 . The belt driving system of  claim 20  wherein the operation of said cooling fan or pump is independent of the rate of rotation of said motor.  
   
   
       22 . The belt driving system of  claim 20  further comprising said cooling fan or pump having an coolant inlet within said frame structure.  
   
   
       23 . The belt driving system of  claim 16  further comprising motor mountings secured to said frame structure and providing support for said shaft.  
   
   
       24 . The belt driving system of  claim 23  comprising at least one clamp mechanism secured within said motor mountings for supporting and preventing rotation of said shaft.  
   
   
       25 . The belt driving system of  claim 24  wherein at least one clamp mechanism includes a resilient material to absorb vibration caused by the outer rotor motor.  
   
   
       26 . The belt driving system of  claim 24  wherein at least one clamp mechanism includes a heat insulation material to stop heat transferring from said pulleys to said frame structure.  
   
   
       27 . The belt driving system of  claim 16  further comprising said stator having a plurality of coolant channels configured so as to permit said coolant to flow through the stator coolant channels in a direction generally parallel to said shaft.  
   
   
       28 . The belt driving system of  claim 16  wherein said motor is constructed by using a fractional pitch winding configuration.  
   
   
       29 . The belt driving system of  claim 16  wherein said motor is constructed with skewed magnets or stator slots.  
   
   
       30 . The belt driving system of  claim 16  wherein said motor is constructed with shaped magnets in order to minimize motor cogging torque.  
   
   
       31 . The belt driving system of  claim 16  wherein said motor is constructed with at least one of a fractional pitch winding configuration, skewed magnets or stator slots, and shaped magnets in order to minimize motor cogging torque.  
   
   
       32 . The belt driving system of  claim 16  further comprising: said shaft having holes through the wall of said shaft thereby allowing at least a portion of said coolant to pass through said air gap between said rotor and said stator.  
   
   
       33 . The belt driving system of  claim 16  further comprising: a thermally conductive rod located within said shaft.  
   
   
       34 . The belt driving system of  claim 33  further comprising: said thermally conductive rod having fins.  
   
   
       35 . The belt driving system of  claim 16  further comprising: said end cap mechanism having a through hole for the passage of coolant.  
   
   
       36 . The belt driving system according to  claim 35  further comprising: said end cap mechanism through hole being shaped and arranged to induce coolant flow.  
   
   
       37 . The belt driving system of  claim 16  further comprising: a fan-type device secured to one of said rotor or said end cap mechanism to induce coolant flow.  
   
   
       38 . The belt driving system of  claim 16  further comprising: said motor being sealed wherein said end cap mechanism does not have through holes and through holes in the wall of the shaft are sealed.  
   
   
       39 . The belt driving system of  claim 16  further comprising: said stator having a plurality of through-holes through a core of said stator to induce coolant flow.  
   
   
       40 . The belt driving system of  claim 16  wherein the belt driving system is configured as a conveyor and includes a control panel structure and operably connected to the motor controller and wherein said control panel includes at least a set of user controls effective to permit a user to control the speed of said belt.  
   
   
       41 . 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.    
   
   
       42 . The treadmill of  claim 41  wherein said coolant channel extends substantially through the length of said stator shaft.  
   
   
       43 . The treadmill of  claim 42  wherein said coolant channel is concentric with said stator shaft and has a generally circular cross section.  
   
   
       44 . The treadmill of  claim 41  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.  
   
   
       45 . The treadmill of  claim 41  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.  
   
   
       46 . The treadmill of  claim 45  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.  
   
   
       47 . The treadmill of  claim 46  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.  
   
   
       48 . The treadmill of  claim 45  wherein said thermally conductive member includes a plurality of fins extending longitudinally along said coolant channel that form said surface areas.  
   
   
       49 . The treadmill of  claim 41  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.  
   
   
       50 . The treadmill of  claim 41  wherein said motor includes at least one end cap which is sealed against air flow through said end cap.  
   
   
       51 . The treadmill of  claim 41  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.  
   
   
       52 . The treadmill of  claim 41  wherein said coolant channel is configured in the outer surface of said stator shaft.  
   
   
       53 . The treadmill of  claim 41  wherein said coolant is a gas.  
   
   
       54 . The treadmill of  claim 53  wherein said gas is air.  
   
   
       55 . The treadmill of  claim 41  wherein said coolant is a liquid.  
   
   
       56 . The treadmill of  claim 41  additionally including a coolant transfer mechanism connected to said stator shaft for transferring said coolant through said coolant channel.  
   
   
       57 . The treadmill of  claim 56  wherein said coolant is gas and said transfer mechanism includes a fan or a blower.  
   
   
       58 . The treadmill of  claim 56  wherein said coolant is a liquid and said transfer mechanism includes a pump.  
   
   
       59 . The treadmill of  claim 56  wherein said transfer mechanism includes a filter for filtering said coolant.  
   
   
       60 . 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.    
   
   
       61 . The treadmill of  claim 60  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.  
   
   
       62 . The treadmill of  claim 61  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.  
   
   
       63 . 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.    
   
   
       64 . The treadmill of  claim 63  wherein said sensing mechanism includes an optical encoder.  
   
   
       65 . The treadmill of  claim 63  wherein said sensing mechanism includes a resolver.  
   
   
       66 . The treadmill of  claim 65  wherein said resolver includes a resolver rotor secured for rotation with said rotor and a resolver stator secured to said stator shaft.  
   
   
       67 . The treadmill of  claim 63  wherein said treadmill does not include a hall effect sensor.  
   
   
       68 . 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.    
   
   
       69 . The treadmill of  claim 68  including both said stator windings having fractional pitch and said stator slots orientated in a skewed relationship with said edges of said permanent magnets.  
   
   
       70 . The treadmill of  claim 69  additionally including said magnet shaping.  
   
   
       71 . The treadmill of  claim 68  including both said stator windings having fractional pitch and said magnet shaping.  
   
   
       72 . The treadmill of  claim 68  including both said stator slots orientated in a skewed relationship with said edges of said permanent magnets and said magnet shaping.  
   
   
       73 . The treadmill of  claim 68  for wherein there are 21 of said stator slots and 8 or 16 of said poles.  
   
   
       74 . 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.    
   
   
       75 . 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.    
   
   
       76 . 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.    
   
   
       77 . 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.    
   
   
       78 . The treadmill of  claim 77  wherein said motor controller is secured within said first frame structure.  
   
   
       79 . 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.