GB2432057A - Brushless motor with rotor flux leakage derived control signals - Google Patents
Brushless motor with rotor flux leakage derived control signals Download PDFInfo
- Publication number
- GB2432057A GB2432057A GB0622131A GB0622131A GB2432057A GB 2432057 A GB2432057 A GB 2432057A GB 0622131 A GB0622131 A GB 0622131A GB 0622131 A GB0622131 A GB 0622131A GB 2432057 A GB2432057 A GB 2432057A
- Authority
- GB
- United Kingdom
- Prior art keywords
- motor
- rotor
- field
- gearbox
- wheelchair
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
- A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
- A61G5/04—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs motor-driven
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2786—Outer rotors
- H02K1/2787—Outer rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/2789—Outer rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2791—Surface mounted magnets; Inset magnets
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61G—TRANSPORT, PERSONAL CONVEYANCES, OR ACCOMMODATION SPECIALLY ADAPTED FOR PATIENTS OR DISABLED PERSONS; OPERATING TABLES OR CHAIRS; CHAIRS FOR DENTISTRY; FUNERAL DEVICES
- A61G5/00—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs
- A61G5/08—Chairs or personal conveyances specially adapted for patients or disabled persons, e.g. wheelchairs foldable
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2786—Outer rotors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
- H02K29/06—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with position sensing devices
- H02K29/08—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with position sensing devices using magnetic effect devices, e.g. Hall-plates, magneto-resistors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/10—Structural association with clutches, brakes, gears, pulleys or mechanical starters
- H02K7/116—Structural association with clutches, brakes, gears, pulleys or mechanical starters with gears
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/22—Auxiliary parts of casings not covered by groups H02K5/06-H02K5/20, e.g. shaped to form connection boxes or terminal boxes
- H02K5/225—Terminal boxes or connection arrangements
Abstract
A brushless electric motor having a permanent magnet rotor, having magnets 16 contained within an annular wall of a rotor cup 18 in slots 19, and a stator 13, housing field coils 14, in which the field coils 14 are energized in accordance with control signals sensed by a field sensor arrangement (Hall effect sensor 15) The signals are derived from a field leaked from the drive magnets through the rotor wall at region 17 which is of reduced thickness. In a wheel chair with motor gearbox combinations mounted to each wheel, the reduced motor dimensions allow the two combination to occupy together less than 15% of the wheelchair width to assist with folding. The control board 22 mounted within the motor casing reduces the need for external circuitry resulting in a more compact joystick arrangement.
Description
<p>1 2432057 Brushless Electric Motors This invention relates to brushless
electric motors, particularly brushless motors having a</p>
<p>field coil system and a permanent magnet rotor.</p>
<p>Such motors have on the rotor, in addition to the permanent drive magnets that effect the rotation by reaction with the field coils in the stator, a set of sensor magnets that effect, through sensors, the activation of the field coils in the correct sequence to drive the rotor.</p>
<p>It is now found that these sensor magnets can be dispensed with, simplifying the construction of the motor and making it more compact and less costly. This is of particular importance in one area of use of this type of motor, namely as a drive motor for wheelchairs and invalid carriages.</p>
<p>The invention comprises a brushless electric motor having a permanent magnet rotor, having magnets contained within an annular wall, and a stator, housing field coils, in which the field coils are energised in accordance with control signals sensed by a field sensor arrangement, characterised in that signals are derived from a field leaked from the drive magnets through the rotor wall.</p>
<p>The leakage field may be afforded by means of a reduction in rotor thickness at a sensing position, which may conveniently be located at an end of the rotor.</p>
<p>The reduction in rotor thickness will be such as will permit a sufficient leakage field to actuate the field sensor arrangement, which may comprise a Hall Effect Device arrangement.</p>
<p>The rotor may comprise a cylindrical cup having internal slots for the drive magnets. The cylindrical cup may have a base by which it is mounted on a motor shaft and an open end which has a reduced external diameter affording a leakage path for magnetic field from the drive magnets.</p>
<p>The invention also comprises a brushless electric motor as set forth above, having control circuitry at least in part contained within the motor casing. A control circuit board may be mounted in a housing of the motor casing so as to extend parallel to the motor shaft.</p>
<p>The invention also comprises a motor and gearbox combination comprising a motor having the features referred to above, and further comprises a vehicle powered by one or more such motors. The motors and motor and gearbox combinations are especially suitable for powering wheelchairs, and the invention comprises a wheelchair so powered.</p>
<p>A motor, a motor and gearbox combination, and a wheelchair according to the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is an axial section through one embodiment of motor; Figure 2 is a view on Arrow 2 of Figure 1; Figure 3 is a perspective view of one embodiment of motor/gearbox combination; Figure 4 is a view like Figure 3 of a second embodiment of motor/gearbox combination; Figure 5 is a view of the combination of Figure 5 mounted to drive a wheelchair wheel; and Figure 6 is a rear view of a wheelchair with a motor driving each of its two main wheels.</p>
<p>The drawings illustrate a brushless electric motor 11 having a permanent magnet rotor 12 and a stator 13 housing field coils 14, in which the field coils 14 are energised in accordance with control signals sensed by a field sensor arrangement 15 which signals are derived from leakage field from the rotor drive magnets 16.</p>
<p>The leakage field is afforded by means of a reduction in rotor thickness at a sensing position 17 which is located at an end 12a of the rotor 12.</p>
<p>The reduction in rotor thickness is such as will permit a sufficient leakage field to actuate the field sensor arrangement 15, which comprises a Hall Effect Device arrangement.</p>
<p>The rotor 12 comprises a cylindrical cup 18 having internal slots 19 for the drive magnets 16. The cylindrical cup 18 has a base 1 8a by which it is mounted on a motor shaft 21 and its open end 12a has a reduced external diameter affording a leakage path for magnetic</p>
<p>field from the drive magnets 16.</p>
<p>The motor can thus be shorter than conventional such motors which have separate sensor magnets on the shaft 21. Fractional horsepower motors of this kind are used inter a/ia to drive wheelchairs, and are usually provided with a gearbox. The reduced motor dimensions, resulting from dispensing with the control magnets, mean a smaller motor/gearbox assembly, which facilitates incorporation into a wheelchair in such fashion that permits enhanced foldability thereof.</p>
<p>Moreover, a control circuit board 22 is mounted in a housing 23 of the motor casing 24 so as to extend parallel to the motor shaft 21. The field sensor arrangement 15 is attached directly to the circuit board 22. This reduces the need for external control circuitry, which can result in a more compact joystick arrangement for controlling a wheelchair Figures 3 and 4 illustrate motors 11 according to the invention with attached gearboxes 41, showing how the gearbox 41 can be arranged in different positions with respect to the motor 11. The gearbox output shaft 42 can also project either side of the gearbox 41.</p>
<p>Figure 5 illustrates how a motor/gearbox combination 61 can be fitted to a wheel 62 and framework 63 of a wheelchair, and Figure 6 shows a rear view of a wheelchair 71 with motor/gearbox combinations 61, with oppositely projecting output shafts, fitted for powering both main wheels 62. It is clear that the small size of the motor/gearbox combination 61 greatly facilitates folding of the wheelchair, the two combinations occupying less than 15% of the width of the wheelchair.</p>
Claims (1)
- <p>Claims: I A brushless electric motor having a permanent magnet rotor,having magnets contained within an annular wall, and a stator, housing field coils, in which the field coils are energised in accordance with control signals sensed by a field sensor arrangement, characterised in that signals are derived from a field leaked from the drive magnets through the rotor wall.</p><p>2 A motor according to claim 1, in which the leakage field is afforded by means of a reduction in rotor thickness at a sensing position.</p><p>3 A motor according to claim 2, in which the sensing position is located at an end of the rotor.</p><p>4 A motor according to any one of claims I to 3, in which the field sensor arrangement comprises a Hall Effect Device arrangement.</p><p>A motor according to any one of claims 1 to 4, in which the rotor comprises a cylindrical cup having internal slots for the drive magnets.</p><p>6 A motor according to claim 5, in which the cylindrical cup has a base by which it is mounted on a motor shaft and an open end which has a reduced external diameter affording a leakage path for magnetic field from the drive magnets.</p><p>7 A brushless electric motor according to any one of claims I to 6, having control circuitry at least in part contained within the motor casing.</p><p>8 A motor according to claim 7, in which a control circuit board is mounted in a housing of the motor casing so as to extend parallel to the motor shaft.</p><p>9 A motor and gearbox combination comprising a motor according to any one of claims ito 10.</p><p>A combination according to claim 9, affording multiple motor-gearbox arrangements.</p><p>11 A combination according to claim 9 r claim 10, in which an output shaft of the gearbox can project from opposite sides thereof.</p><p>12 A vehicle powered by one or more motors according to any one of claims I to 11.</p><p>13 A vehicle according to claim 12, comprising a wheelchair.</p><p>14 A wheelchair according to claim 13, having two main wheels each driven by a motor according to any one of claims 1 to 10 or a motor/gearbox combination according to any one of claims 9 to 11.</p><p>A wheelchair according to claim 13 or claim 14, in which the motor/gearbox combinations occupy less than 15% of the width of the wheelchair.</p>
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB0522723.6A GB0522723D0 (en) | 2005-11-08 | 2005-11-08 | Brushless electric motors |
Publications (2)
Publication Number | Publication Date |
---|---|
GB0622131D0 GB0622131D0 (en) | 2006-12-20 |
GB2432057A true GB2432057A (en) | 2007-05-09 |
Family
ID=35516514
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GBGB0522723.6A Pending GB0522723D0 (en) | 2005-11-08 | 2005-11-08 | Brushless electric motors |
GB0622131A Withdrawn GB2432057A (en) | 2005-11-08 | 2006-11-07 | Brushless motor with rotor flux leakage derived control signals |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GBGB0522723.6A Pending GB0522723D0 (en) | 2005-11-08 | 2005-11-08 | Brushless electric motors |
Country Status (2)
Country | Link |
---|---|
GB (2) | GB0522723D0 (en) |
WO (1) | WO2007054676A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57166871A (en) * | 1981-04-03 | 1982-10-14 | Japan Servo Co Ltd | Dc brushless motor |
JPH0352546A (en) * | 1989-07-20 | 1991-03-06 | Canon Electron Inc | Brushless motor |
EP1172925A2 (en) * | 2000-07-11 | 2002-01-16 | Nissan Motor Co., Ltd. | Pole position detector for motor |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ATE54517T1 (en) * | 1985-09-23 | 1990-07-15 | Siemens Ag | ELECTRIC MOTOR, IN PARTICULAR PERMANENT MAGNET EXCITED OUTSIDE ROTOR MOTOR. |
JP3017953B2 (en) * | 1996-07-24 | 2000-03-13 | 株式会社東芝 | Motor rotor and method of manufacturing the same |
JP3998118B2 (en) * | 2000-10-10 | 2007-10-24 | 本田技研工業株式会社 | Electric vehicle |
EP1464106A1 (en) * | 2002-01-11 | 2004-10-06 | ebm-papst St. Georgen GmbH & Co. KG | Miniature fan or micro-fan |
JP3769565B2 (en) * | 2003-10-10 | 2006-04-26 | 住友重機械工業株式会社 | Geared motor used in electric wheelchair drive device |
-
2005
- 2005-11-08 GB GBGB0522723.6A patent/GB0522723D0/en active Pending
-
2006
- 2006-11-07 WO PCT/GB2006/004144 patent/WO2007054676A1/en active Application Filing
- 2006-11-07 GB GB0622131A patent/GB2432057A/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57166871A (en) * | 1981-04-03 | 1982-10-14 | Japan Servo Co Ltd | Dc brushless motor |
JPH0352546A (en) * | 1989-07-20 | 1991-03-06 | Canon Electron Inc | Brushless motor |
EP1172925A2 (en) * | 2000-07-11 | 2002-01-16 | Nissan Motor Co., Ltd. | Pole position detector for motor |
Also Published As
Publication number | Publication date |
---|---|
GB0522723D0 (en) | 2005-12-14 |
GB0622131D0 (en) | 2006-12-20 |
WO2007054676A1 (en) | 2007-05-18 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |