CA2336514A1 - Unitary axial flux pole shoe - Google Patents
Unitary axial flux pole shoe Download PDFInfo
- Publication number
- CA2336514A1 CA2336514A1 CA 2336514 CA2336514A CA2336514A1 CA 2336514 A1 CA2336514 A1 CA 2336514A1 CA 2336514 CA2336514 CA 2336514 CA 2336514 A CA2336514 A CA 2336514A CA 2336514 A1 CA2336514 A1 CA 2336514A1
- Authority
- CA
- Canada
- Prior art keywords
- pole shoe
- stator
- adjacent
- pole
- poles
- 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.)
- Abandoned
Links
Classifications
-
- 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
- H02K1/12—Stationary parts of the magnetic circuit
- H02K1/14—Stator cores with salient poles
- H02K1/146—Stator cores with salient poles consisting of a generally annular yoke with salient poles
- H02K1/148—Sectional cores
-
- 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
- H02K1/08—Salient poles
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Iron Core Of Rotating Electric Machines (AREA)
Abstract
An unitary pole shoe for mounting adjacent a stator in an electric motor. The pole shoe includes several pole shoe sections, each pole shoe section is mounted adjacent a stator pole. Several bridges join the pole shoe sections. The bridges are located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized.
Description
02/01/01 10:29 FAX 219 294 8151 CTS CORPORATE 1009 CT~2o35 BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
This invention relates to electric motors and/or achrators. In particular, there is a unitary pole shoe that minimizes flux leakage for an electric motor that replaces multiple pole shoes.
1. FIELD OF THE INVENTION
This invention relates to electric motors and/or achrators. In particular, there is a unitary pole shoe that minimizes flux leakage for an electric motor that replaces multiple pole shoes.
2. DESCRIPTION OF THE RELATED ART
Electromechanical rotary actuators and motors that operate with air-gap magnetic flux in the axial direction usually have a soft-magnetic stator with salient poles- The tops of the poles face the air gap that separates the rotor from the stator.
On the stator, the space between consecutive poles is determined by the dimensions of the insulated coils which, when energized with electric current, convert the stator poles into electromagnets.
The rotary actuator or motor develops torque that is directly related to the coils' current over a rotation angle that corresponds, approximately, to the arc spanned by one salient pole. To increase this angle, individual soft-magnetic "pole shoes" are placed on top of each stator pole- At the air gap, the shoes present an arc that is wider than the arc of the salient poles.
The pole shoes have to be placed, one over each stator pole, accurately, and then secured in place pemnanently_ Common numbers of pole shoes are 2 and 4.
although larger numbers, such as 8 and 10, are also used. The placement and 02/01/01 10:29 FAX 219 294 8151 CTS CORPORATE ~ 004 CT&2035 attachment of multiple pole shoes adds complexity and cost to the production of electric motors.
If the pole shoes are not evenly spaced, then the pertormance of the rotary actuator or motor deteriorates, and the expelled useful rotation range may not be S possible. For example, pole shoes that are too close to each other favor excessive magnetic leakage between them, thus helping saturate their stator poles with magnetic flux that does not contribute to the development of any rotational torque. The leaking flux also contributes to a more inefficient motor.
Therefore, there is a current unmet need for a pole shoe that is readily manufacturable and assembled into an electric motor at a low cost and that minimizes magnetic flux leakage between stator poles.
SUMMARY OF THE INVENTION
It is a feature of the invention to provide a unitary pole shoe for mounting adjacent a stator in an electric motor. The pole shoe includes several pole shoe sections, each pole shoe section is mounted adjacent a stator pole. Several bridges join the pole shoe sections. The bridges are located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized.
The invention resides not in any one of these features per se, but rather in the particular combination of ail of them herein disclosed and claimed. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for cartying 02/01/01 10:0 FAX 219 294 8151 CTS CORPORATE f~]005 G'rs-2035 out the several purposes of the present invention. further, the abstract is neither intended to define the invention of the application, which is measured by the claims, neither is it intended to be limiting as to the scope of the invention in any way.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of the preferred embodiment of the unitary axial flux pole shoe with a stator.
Fig. 2 is a top view of the unitary axial flux pole shoe of figure 1.
Fig. 3 is a cross sectional view of figure 2 along section lines A-A.
to Fig. 4 is a top view of an alternative embodiment of the unitary axial flux pole shoe.
It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Refen~ing to figures 1,2 and 3 the prefer-ed embodiment of the unitary axial flux pole shoe 30 is shown. A stator assembly 10 has a stator 12 with a unitary pole shoe 30 mounted thereon. Stator assembly 10 is part of a rotary actuator or rotating electric motor.
Stator 12 has a base 13 with four stator poles 14 extending therefrom, and a stator cavity 15. Stator gaps 16 are located between the stator poles 14_ Holes 17 are located at the top of poles 14. Holes 17 receive fasteners 24 to attach pole shoe 30 to stator 12. Several 02i01/01 10:0 FAQ 219 294 8151 CTS CORPORATE 0 008 recesses 18 are located on the stator poles 18 to help align and secure pole shoe 30.
Stator 12 is preferably formed from a sintered powdered metal. A wire winding 20 is wound around stator pole 14. An electrical potential is applied to winding 20 in order to generate a flux field 22 extending axially to the stator poles in the direction shown by the arrows in figure 1. By regulating either the direction of current passing through the winding or by changing the direction of the winding around the poles, each column can become 'a north or south elector-magnet. The flux field 22 acts upon a rotor (not shown) that contains magnets. The flux field causes an opposing field on the magnet to be biased away from the poles and to cause the rotor to rotate. During operation, the stator poles generate flux l0 22 that moves perpendicular to the plane of the pole shoe 30.
Disc shaped pole shoe 30 has four quarter circle shaped sections 32. Pole shoe 30 is preferably stamped from conventional carbon steel sheet metal. Prior art pole shoes are formed by pressing and sintering powdered metal. The pole shoe 30 is mounted on stator 12. Each pole shoe section 32 is mounted adjacent a stator pole 14.
Bridges 34 are formed between sections 32 and link the pole shoe sections together. The bridges 32 are located out of the main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized. The sections 32 define a slot 35 between adjacent sections. A shaft aperture 36 passes through the center of the pole shoe 30. A shaft (not shown) would pass through aperture 36. Several notches 38 are located on an inner circumferential surface 40 adjacent aperture 36. The purpose of notches 38 is to reduce the cross-section of bridges 34. Several outer alignment notches 42 are located on an outer circumferential surface 48. Chamfered holes 44 allow fasteners 02/01/01 10:50 FAX 219 294 8151 CTS CORPORATE ~ 007 CT5.2035 24 to pass through. The alignment notches facilitate accurate and fast assembly of the rotary actuator. A thrust bearing support 46 is formed around the aperture.
The thrust bearing support 46 carries a thrust bearing (not shown) that supports the shaft.
The present invention allows the prior art multiple set of pole shoes to be replaced by one single or unitary part, preferably one stamped out of sheet-metal. The unitary pole shoe incorporates the individual pole shoes that are joined by bridges and also incorporates a thrust bearing support. These bridges have to be relatively thin and out of the main path of flux that links two consecutive poles. This avoids the problem of excessive flux leakage between adjacent pole shoes that are too close_ While the pole shoe was shown fastened to the stator poles with screws, other fastening methods can also be used. For example, the pole shoe can be welded to the stator pole or can be attached with rivets or an adhesive.
The advantages of the present invention are:
1. The assembly is greatly simplified because there is only one single pole shoe to be positioned instead of 2, 4, 6, 8, 10, etc. individual pole shoes.
2. Even spacing of the pole shoes is guaranteed by the stamping operation.
3_ The cost of materials and assembly is reduced.
4. The stamped part can incorporate features on its outer and inner edges that help the mechanical assembly of the rotary actuator or motor while locating the pole piece on the stator and or while locating the actuator housing around the pole shoe.
5. A concave "thrust bearing support" can be formed at the center of the stamped part, thus incorporating what normally is another separate component of the actuator or 02/01/01 10:x0 FAX 219 294 6151. _ CTS CORPORATE f~o08 CT~r2035 motor.
Referring to figure 4, an alternative embodiment of the unitary axial flux pole shoe 60 is shown. Pole shoe 60 is similar to pole shoe 30 except that the bridges 62 are oriented diagonally between the pole shoe sections 32. Bridges 62 form an inner slot 64 and an outer slot 66. The bridges 62 connect the pole shoe sections 32, while at the same time being located out of the main flux path so as to minimize flux leakage.
l0
Electromechanical rotary actuators and motors that operate with air-gap magnetic flux in the axial direction usually have a soft-magnetic stator with salient poles- The tops of the poles face the air gap that separates the rotor from the stator.
On the stator, the space between consecutive poles is determined by the dimensions of the insulated coils which, when energized with electric current, convert the stator poles into electromagnets.
The rotary actuator or motor develops torque that is directly related to the coils' current over a rotation angle that corresponds, approximately, to the arc spanned by one salient pole. To increase this angle, individual soft-magnetic "pole shoes" are placed on top of each stator pole- At the air gap, the shoes present an arc that is wider than the arc of the salient poles.
The pole shoes have to be placed, one over each stator pole, accurately, and then secured in place pemnanently_ Common numbers of pole shoes are 2 and 4.
although larger numbers, such as 8 and 10, are also used. The placement and 02/01/01 10:29 FAX 219 294 8151 CTS CORPORATE ~ 004 CT&2035 attachment of multiple pole shoes adds complexity and cost to the production of electric motors.
If the pole shoes are not evenly spaced, then the pertormance of the rotary actuator or motor deteriorates, and the expelled useful rotation range may not be S possible. For example, pole shoes that are too close to each other favor excessive magnetic leakage between them, thus helping saturate their stator poles with magnetic flux that does not contribute to the development of any rotational torque. The leaking flux also contributes to a more inefficient motor.
Therefore, there is a current unmet need for a pole shoe that is readily manufacturable and assembled into an electric motor at a low cost and that minimizes magnetic flux leakage between stator poles.
SUMMARY OF THE INVENTION
It is a feature of the invention to provide a unitary pole shoe for mounting adjacent a stator in an electric motor. The pole shoe includes several pole shoe sections, each pole shoe section is mounted adjacent a stator pole. Several bridges join the pole shoe sections. The bridges are located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized.
The invention resides not in any one of these features per se, but rather in the particular combination of ail of them herein disclosed and claimed. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for cartying 02/01/01 10:0 FAX 219 294 8151 CTS CORPORATE f~]005 G'rs-2035 out the several purposes of the present invention. further, the abstract is neither intended to define the invention of the application, which is measured by the claims, neither is it intended to be limiting as to the scope of the invention in any way.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of the preferred embodiment of the unitary axial flux pole shoe with a stator.
Fig. 2 is a top view of the unitary axial flux pole shoe of figure 1.
Fig. 3 is a cross sectional view of figure 2 along section lines A-A.
to Fig. 4 is a top view of an alternative embodiment of the unitary axial flux pole shoe.
It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Refen~ing to figures 1,2 and 3 the prefer-ed embodiment of the unitary axial flux pole shoe 30 is shown. A stator assembly 10 has a stator 12 with a unitary pole shoe 30 mounted thereon. Stator assembly 10 is part of a rotary actuator or rotating electric motor.
Stator 12 has a base 13 with four stator poles 14 extending therefrom, and a stator cavity 15. Stator gaps 16 are located between the stator poles 14_ Holes 17 are located at the top of poles 14. Holes 17 receive fasteners 24 to attach pole shoe 30 to stator 12. Several 02i01/01 10:0 FAQ 219 294 8151 CTS CORPORATE 0 008 recesses 18 are located on the stator poles 18 to help align and secure pole shoe 30.
Stator 12 is preferably formed from a sintered powdered metal. A wire winding 20 is wound around stator pole 14. An electrical potential is applied to winding 20 in order to generate a flux field 22 extending axially to the stator poles in the direction shown by the arrows in figure 1. By regulating either the direction of current passing through the winding or by changing the direction of the winding around the poles, each column can become 'a north or south elector-magnet. The flux field 22 acts upon a rotor (not shown) that contains magnets. The flux field causes an opposing field on the magnet to be biased away from the poles and to cause the rotor to rotate. During operation, the stator poles generate flux l0 22 that moves perpendicular to the plane of the pole shoe 30.
Disc shaped pole shoe 30 has four quarter circle shaped sections 32. Pole shoe 30 is preferably stamped from conventional carbon steel sheet metal. Prior art pole shoes are formed by pressing and sintering powdered metal. The pole shoe 30 is mounted on stator 12. Each pole shoe section 32 is mounted adjacent a stator pole 14.
Bridges 34 are formed between sections 32 and link the pole shoe sections together. The bridges 32 are located out of the main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized. The sections 32 define a slot 35 between adjacent sections. A shaft aperture 36 passes through the center of the pole shoe 30. A shaft (not shown) would pass through aperture 36. Several notches 38 are located on an inner circumferential surface 40 adjacent aperture 36. The purpose of notches 38 is to reduce the cross-section of bridges 34. Several outer alignment notches 42 are located on an outer circumferential surface 48. Chamfered holes 44 allow fasteners 02/01/01 10:50 FAX 219 294 8151 CTS CORPORATE ~ 007 CT5.2035 24 to pass through. The alignment notches facilitate accurate and fast assembly of the rotary actuator. A thrust bearing support 46 is formed around the aperture.
The thrust bearing support 46 carries a thrust bearing (not shown) that supports the shaft.
The present invention allows the prior art multiple set of pole shoes to be replaced by one single or unitary part, preferably one stamped out of sheet-metal. The unitary pole shoe incorporates the individual pole shoes that are joined by bridges and also incorporates a thrust bearing support. These bridges have to be relatively thin and out of the main path of flux that links two consecutive poles. This avoids the problem of excessive flux leakage between adjacent pole shoes that are too close_ While the pole shoe was shown fastened to the stator poles with screws, other fastening methods can also be used. For example, the pole shoe can be welded to the stator pole or can be attached with rivets or an adhesive.
The advantages of the present invention are:
1. The assembly is greatly simplified because there is only one single pole shoe to be positioned instead of 2, 4, 6, 8, 10, etc. individual pole shoes.
2. Even spacing of the pole shoes is guaranteed by the stamping operation.
3_ The cost of materials and assembly is reduced.
4. The stamped part can incorporate features on its outer and inner edges that help the mechanical assembly of the rotary actuator or motor while locating the pole piece on the stator and or while locating the actuator housing around the pole shoe.
5. A concave "thrust bearing support" can be formed at the center of the stamped part, thus incorporating what normally is another separate component of the actuator or 02/01/01 10:x0 FAX 219 294 6151. _ CTS CORPORATE f~o08 CT~r2035 motor.
Referring to figure 4, an alternative embodiment of the unitary axial flux pole shoe 60 is shown. Pole shoe 60 is similar to pole shoe 30 except that the bridges 62 are oriented diagonally between the pole shoe sections 32. Bridges 62 form an inner slot 64 and an outer slot 66. The bridges 62 connect the pole shoe sections 32, while at the same time being located out of the main flux path so as to minimize flux leakage.
l0
Claims (14)
1. A unitary pole shoe for mounting adjacent a stator in an electric motor, comprising:
a) a plurality of pole shoe sections, each pole shoe section mounted adjacent a stator pole; and b) a plurality of bridges joining the pole shoe sections, the bridges located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized.
a) a plurality of pole shoe sections, each pole shoe section mounted adjacent a stator pole; and b) a plurality of bridges joining the pole shoe sections, the bridges located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized.
2. The pole shoe according to claim 1, wherein the pole shoe has a shaft aperture passing therethrough.
3. The pole shoe according to claim 2, wherein the pole shoe has alignment notches on an inner circumferential surface adjacent the aperture.
4. The pole shoe according to claim 3, wherein the pole shoe has alignment notches on an outer circumferential surface.
5. The pole shoe according to claim 1, wherein the pole shoe has a thrust bearing support attached around the aperture.
6. The pole shoe according to claim 1, wherein the pole shoe is disc shaped.
7. The pole shoe according to claim 6, wherein the stator poles generate flux that is perpendicular to the plane of the disc.
8. A single piece pole shoe for a rotary actuator, the actuator having a shaft, comprising.
a) a plurality of pole shoe sections disposed circumferentially around the shaft, each pole shoe section mounted adjacent a stator pole;
b) a plurality of bridges joining the pole shoe sections, the bridges located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized; and c) a shaft aperture passing through the pole shoe.
a) a plurality of pole shoe sections disposed circumferentially around the shaft, each pole shoe section mounted adjacent a stator pole;
b) a plurality of bridges joining the pole shoe sections, the bridges located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized; and c) a shaft aperture passing through the pole shoe.
9. The pole shoe according to claim 8, wherein the pole shoe has alignment notches on an inner circumferential surface adjacent the aperture.
10. The pole shoe according to claim 9, wherein the pole shoe has alignment notches on an outer circumferential surface.
11. The pole shoe according to claim 10, wherein the pole shoe has a thrust bearing support attached around the aperture.
12. The pole shoe according to claim 8, wherein the pole shoe is disc shaped.
13. The pole shoe according to claim 8, wherein the stator poles generate flux that is perpendicular to the plane of the disc.
14. A stator assembly for a rotary actuator, the actuator having a shaft, comprising:
(a) a stator having a plurality of stator poles;
(b) a plurality of pole shoe sections disposed circumferentially around the shaft, each pole shoe section mounted adjacent one of the stator poles;
(c) a plurality of bridges joining the pole shoe sections, the bridges located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized; and (d) a shaft aperture passing through the pole shoe.
(a) a stator having a plurality of stator poles;
(b) a plurality of pole shoe sections disposed circumferentially around the shaft, each pole shoe section mounted adjacent one of the stator poles;
(c) a plurality of bridges joining the pole shoe sections, the bridges located out of a main flux path between any two adjacent stators poles such that flux leakage between the adjacent stator poles is minimized; and (d) a shaft aperture passing through the pole shoe.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2336514 CA2336514A1 (en) | 2001-02-14 | 2001-02-14 | Unitary axial flux pole shoe |
| PCT/CA2001/000633 WO2002065616A1 (en) | 2001-02-14 | 2001-05-04 | Unitary axial flux pole shoe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2336514 CA2336514A1 (en) | 2001-02-14 | 2001-02-14 | Unitary axial flux pole shoe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2336514A1 true CA2336514A1 (en) | 2002-08-14 |
Family
ID=4168366
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2336514 Abandoned CA2336514A1 (en) | 2001-02-14 | 2001-02-14 | Unitary axial flux pole shoe |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2336514A1 (en) |
| WO (1) | WO2002065616A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2605560B (en) * | 2021-01-22 | 2023-05-10 | Yasa Ltd | Stator assembly flux alignment |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5089730A (en) * | 1990-05-18 | 1992-02-18 | North American Philips Corporation | Low noise DC electric motor |
| AUPM827094A0 (en) * | 1994-09-20 | 1994-10-13 | Queensland Railways | Open stator axial flux electric motor |
| DE19756575B4 (en) * | 1997-12-18 | 2009-08-13 | Siemens Ag | electric motor |
| IT1312180B1 (en) * | 1999-04-15 | 2002-04-09 | Rcv S R L | BRUSHLESS AXIAL TRAFER MOTOR AND METHOD FOR ITS MANUFACTURE. |
-
2001
- 2001-02-14 CA CA 2336514 patent/CA2336514A1/en not_active Abandoned
- 2001-05-04 WO PCT/CA2001/000633 patent/WO2002065616A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| WO2002065616A1 (en) | 2002-08-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |