CA2133640A1 - Method and apparatus for manufacturing a rotor assembly - Google Patents
Method and apparatus for manufacturing a rotor assemblyInfo
- Publication number
- CA2133640A1 CA2133640A1 CA002133640A CA2133640A CA2133640A1 CA 2133640 A1 CA2133640 A1 CA 2133640A1 CA 002133640 A CA002133640 A CA 002133640A CA 2133640 A CA2133640 A CA 2133640A CA 2133640 A1 CA2133640 A1 CA 2133640A1
- Authority
- CA
- Canada
- Prior art keywords
- magnets
- rotor assembly
- shaft
- cover
- frustoconical
- 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
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/278—Surface mounted magnets; Inset magnets
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K15/00—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
- H02K15/02—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
- H02K15/03—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies having permanent magnets
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Permanent Field Magnets Of Synchronous Machinery (AREA)
- Manufacture Of Motors, Generators (AREA)
Abstract
Past methods and apparatus for manufacturing a rotor assembly have been used to provide rotor assemblies for rotating electric machines. Many of these electric machines rotate at low speeds. The present method and apparatus for manufacturing a rotor assembly can be used to make a rotor assembly (16) to be used at high speeds. The rotor aassembly (16) includes a shaft (24) having a frustoconical mounting surface (26) defined thereon and having a plurality of magnets (70) attached to the frustoconical mounting surface (26). A cover (80) having a frustoconical inner surface (82) surrounds the magnets (70) and compressively secures the magnets (70) to the shaft (24). The compressive forces applied by the cover (80) and the adhesive used to secure the magnets (70) insuring that a positive contact pressure exists between the magnets (70) and the shaft (24) during operation of the electric machine.
Description
`~ 94/22203 -~ 1 3 3 6 ~ o PCT/US94/00692 Description METHOD AND APPARATUS FOR MANUFACTI~RIM~:
~ ROTOR ASSEMBLY
Technical Field This invention relates generally to an electric machine and more particularly to a method and `
apparatus for making a rotor assembly having magnets attached thereto.
Backaround Art Permanent maqnet rotors are frequently used in electric machines such as motors and generators.
In many applications, permanent magnets are secured to a rotor hub or shaft by any of a variety of means.
Care must be taken to assure that such securement prevents the magnets from moving either axially or radially. If axial movement is permitted, one or more magnets may not properly align with an armature with the consequence being that the generator efficiency diminishes. If radial movement occurs, the probability of interfering contact between the rotor and the stator exists, and the resulting frictional drag and/or damage to generator parts comes into existence.
As may be expected, securement of magnets increasingly becomes a problem with increased rotor speeds due to the increasing forces tending to cause magnet movement, particularly in the radial direction, with the increasing centrifugal force accompanying increasing rotational speeds. Thus, in many instances where there are relatively high speeds, and permanent magnet rotors are required, securement of the magnets against both axial and radial displacement is accomplished by sandwiching the magnets between W094/22203 PCT~S94/00692 -, side plates which prevent axial displacement and by winding a fibrous material such as carbon fiber about the peripheries of the side plates and the magnets to provide radial retention. An example of this approach is disclosed in U.S. Patent No. 4,674,178 issued June 23, 1987 to Navinchandra R. Patel. P*el's patent discloses a rotor assembly having th~è~permanent magnets attached thereto by a fibrous winding which is devoid of loose or potentially loose fibers and ends of the windings. The permanent magnets are disposed in a hub and filler material is located between adjacent ones of the magnets. Axially spaced, opposite side plates are located on the hub to sandwich the magnets and the filler material.
Another method and apparatus for assembling a rotor is disclosed in U.S. Patent No. 4,918,802 issued April 24, l99O to Edward J. Schaefer.
Schaefer's patent discloses a rotor assembly having a plurality of permanent magnet segments and an outer sleeve or cylinder. A thin-walled metal cylinder is fashioned and arcuate magnet segments are positioned in angularly spaced relation against the interior surface of the cylinder. The seqments are displaced radially outwardly to stretch or expand the outer cylinder, and the segments are then supported in the outwardly displaced position. The segments may be displaced by a variety of devices including an expanding mandrel, tapered part of a shaft and a tapered ring.
Another problem encountered with rotors of the type disclosed is in the difficulty in achieving a balance about the intended rotational axis of the rotor. When balance can not be achieved, operation of the generator containing the rotor will result in the ~: :
~094/2~03 21 3 ~ 6 ~ 0 PGT~S94/00692 generation of vibration which can deleteriously affect the life of bearings and other generator components.
The present invention is directed to overcoming one or more of the above problems.
Disclosure of the Invention In one aspect of the invention, a rotor assembly is comprised of a shaft having a first end portion and a second end portion and a frustoconical surface defined thereon interposed the first and second end portion. A plurality of magnets are attached to the frustoconical surface. A cover has a preestablished inner frustoconical surface in contact with the magnets and a pair of end flanges are - 15 attached to the shaft.
In another aspect of the invention, a method of manufacturing a rotor assembly including a shaft having a frustoconical surface defined thereon, a plurality of magnets, a cover and at least an end flange is comprised of the steps of attaching the plurality of magnets to the frustoconical surface of the shaft. Positioning the cover about the plurality of magnets and attaching the end flange to the shaft.
Brief Description of the Drawings FIG. 1 is a partial~ly sectioned side view of an electric machine embodying the present invention;
FIG. 2 is an enlarged sectioned view of a rotor assembly and a portion of an outer case;
FIG. 3 is a sectional view taken along lines 3 - 3 of FIG. 2 ;
FIG. 4 is an explo~ed assembly view of the rotor assembly; and W094/~03 PCT~S94/00692 FIG~ 5 is an enlarged sectional view of an alternate embodiment of a rotor assembly and a portion of an outer case of the present invention.
Best Mode for Carr~ina Out the Invention Referring to FIG. 1~ an electric machine lO
such a~ a generator or motor is shown. The machine 10 includes a generally cylindrical multipiece outer case 12 having a central axis 14. Rotatably positioned within the case 12 and centered on the axis 14 is a rotor assembly 16 being supported at a first end portion 18 and a second end portion 20 in a conventional manner, such as by a plurality of bearinqs 22, of which only one is shown. The rotor assembly 16 is either drivingly connected to a power source, if used as a generator, or if used as a motor is connected to a mechanical mechanism such as a compressor or gear drive, not shown.
In this application as further shown in FIG.
~ ROTOR ASSEMBLY
Technical Field This invention relates generally to an electric machine and more particularly to a method and `
apparatus for making a rotor assembly having magnets attached thereto.
Backaround Art Permanent maqnet rotors are frequently used in electric machines such as motors and generators.
In many applications, permanent magnets are secured to a rotor hub or shaft by any of a variety of means.
Care must be taken to assure that such securement prevents the magnets from moving either axially or radially. If axial movement is permitted, one or more magnets may not properly align with an armature with the consequence being that the generator efficiency diminishes. If radial movement occurs, the probability of interfering contact between the rotor and the stator exists, and the resulting frictional drag and/or damage to generator parts comes into existence.
As may be expected, securement of magnets increasingly becomes a problem with increased rotor speeds due to the increasing forces tending to cause magnet movement, particularly in the radial direction, with the increasing centrifugal force accompanying increasing rotational speeds. Thus, in many instances where there are relatively high speeds, and permanent magnet rotors are required, securement of the magnets against both axial and radial displacement is accomplished by sandwiching the magnets between W094/22203 PCT~S94/00692 -, side plates which prevent axial displacement and by winding a fibrous material such as carbon fiber about the peripheries of the side plates and the magnets to provide radial retention. An example of this approach is disclosed in U.S. Patent No. 4,674,178 issued June 23, 1987 to Navinchandra R. Patel. P*el's patent discloses a rotor assembly having th~è~permanent magnets attached thereto by a fibrous winding which is devoid of loose or potentially loose fibers and ends of the windings. The permanent magnets are disposed in a hub and filler material is located between adjacent ones of the magnets. Axially spaced, opposite side plates are located on the hub to sandwich the magnets and the filler material.
Another method and apparatus for assembling a rotor is disclosed in U.S. Patent No. 4,918,802 issued April 24, l99O to Edward J. Schaefer.
Schaefer's patent discloses a rotor assembly having a plurality of permanent magnet segments and an outer sleeve or cylinder. A thin-walled metal cylinder is fashioned and arcuate magnet segments are positioned in angularly spaced relation against the interior surface of the cylinder. The seqments are displaced radially outwardly to stretch or expand the outer cylinder, and the segments are then supported in the outwardly displaced position. The segments may be displaced by a variety of devices including an expanding mandrel, tapered part of a shaft and a tapered ring.
Another problem encountered with rotors of the type disclosed is in the difficulty in achieving a balance about the intended rotational axis of the rotor. When balance can not be achieved, operation of the generator containing the rotor will result in the ~: :
~094/2~03 21 3 ~ 6 ~ 0 PGT~S94/00692 generation of vibration which can deleteriously affect the life of bearings and other generator components.
The present invention is directed to overcoming one or more of the above problems.
Disclosure of the Invention In one aspect of the invention, a rotor assembly is comprised of a shaft having a first end portion and a second end portion and a frustoconical surface defined thereon interposed the first and second end portion. A plurality of magnets are attached to the frustoconical surface. A cover has a preestablished inner frustoconical surface in contact with the magnets and a pair of end flanges are - 15 attached to the shaft.
In another aspect of the invention, a method of manufacturing a rotor assembly including a shaft having a frustoconical surface defined thereon, a plurality of magnets, a cover and at least an end flange is comprised of the steps of attaching the plurality of magnets to the frustoconical surface of the shaft. Positioning the cover about the plurality of magnets and attaching the end flange to the shaft.
Brief Description of the Drawings FIG. 1 is a partial~ly sectioned side view of an electric machine embodying the present invention;
FIG. 2 is an enlarged sectioned view of a rotor assembly and a portion of an outer case;
FIG. 3 is a sectional view taken along lines 3 - 3 of FIG. 2 ;
FIG. 4 is an explo~ed assembly view of the rotor assembly; and W094/~03 PCT~S94/00692 FIG~ 5 is an enlarged sectional view of an alternate embodiment of a rotor assembly and a portion of an outer case of the present invention.
Best Mode for Carr~ina Out the Invention Referring to FIG. 1~ an electric machine lO
such a~ a generator or motor is shown. The machine 10 includes a generally cylindrical multipiece outer case 12 having a central axis 14. Rotatably positioned within the case 12 and centered on the axis 14 is a rotor assembly 16 being supported at a first end portion 18 and a second end portion 20 in a conventional manner, such as by a plurality of bearinqs 22, of which only one is shown. The rotor assembly 16 is either drivingly connected to a power source, if used as a generator, or if used as a motor is connected to a mechanical mechanism such as a compressor or gear drive, not shown.
In this application as further shown in FIG.
2, the rotor assembly 16 includes a shaft 24 having a mounting surface 26 thereon and a necked down portion 28 at each end on which the bearings 22 are positioned. A pair of end flanges 30 having a bore 32 therein are pressed onto the necked down portion 28 at each of the first end portions 18 and the second end portion 20. The mounting surface 26 is interposed the first end portion 18 and the second end portion 20 and between the end flanges 30 has a generally frustoconical contour and has a preestablished length.
The frustoconical contour has a preestablished taper which, in this application, is between about 1 to 2 degrees .
In this application, the rotor assembly 16 further includes an expander turbine 40 formed as a part of one of the end flanges 30. As best shown in ~133640 FIG. 1 and in the top portion of FIGS. 2 and 5, the expander turbine 40 and the end flange 30 are ~ integral. As an alternatiYe best shown in the bottom ~; portion of FIG. 2, the expander turbine 40 and the end l;
flanges 30 can be separate pieces which are pressed onto the shaft 24. As a further alternative best shown in the bottom portion of FIG. 5, the end flange 30 can be integral with the shaft 24 and the expander ~; ~ turbine 40 can be a separate piece which is pressed - 10 onto the shaft 24.
As further shown in FIG. 3, the frustoconical contour of the mounting surface 26 includes a plurality of generally rectangular flat portions 68. In this application, eight (8) flat portions are used. Each of the generally rectangular flat portions 68 has a length which extends between the end flanges 30 and has a preestablished width. A !.
permanent magnet 70 is attached to each of the flats using a glue having the characteristics of being pliable and non-hardening at low temperatures, such as a room temperature vulcanizing material such as Armstrong A 12 adhesive.
As an alternative, the magnets could be energizable rather than being permanent magnets 70 without changing the gist of the invention. In this application as best shown in FIG. 3, each of the magnets 70 has a flat rectangular base surface 72 defined thereon which is attached to respective rectangular flat portions 68 of the frustoconical contour of the mounting surface 26. A cross-section of each magnet 70 includes the base surface 72, a pair of sides 74 extending theref-om and an arcuate surface 76 connected between the pair of sides 74. In the assembled position, a gap 78 is formed between respective sides 74 of adjacent magnets 70. The .~:
W094/2~03 PCT~S94/00692 ";~
'~133640 magnets 70, when attached to the flat portion 68, are each in contact with the adjacent magnets 70 at the junctures between the sides 74 and the base surfa e 72. As an alternative, a small gap could be provided between corresponding sides 74 o,f~adjacent magnets 70.
If the gap exists it will be filled with glue such as Armstrong A 12. Positioned about the arcuate surface 76 of each of the magnets 70 is a non-magnetic cover 80. As an alternative shown in FIG. 5, the rotor assembly 16 could include an integral formed shaft 24 and one of the end flange 30. The second end flange 30 would be a~tached to the integral formed shaft 24 after attachment of the magnets 70 and the cover 80.
In this application, the cover 80 is made-up of a composite material, such as being formed by winding a fiber, such as a carbon fiber in a curable resin such as epoxy resin, circumferentially about a tapered or frustoconical anvil having a preestablished major diameter and a preestablished minor diameter.
The winding about the anvil results in the cover 80 having a preestablished inner frustoconical surface 82. ~he cover 80 has a preestablished length being generally equal to the length of the frustoconical contour of the mounting surface 26 and has a preestablished thickness. As an alternative, the cover 80 could be made of a non-magnetic metal without changing the concept.
As best shown in FIG. 4, the rotor assembly 16 is assembled as follows. The mounting surface 26 of the shaft 24 has Armstrong A 12 applied thereto and each of the magnets 70 are attached to the generally rectangular flat portions 58. As an alternative ea~h of the rectangular base surface 72 of each of the magnets 70 and the mounting surface 26 could have Armstrong A 12 applied thereto and the magnets 70 2133~40 !0941~03 - PCT~S94/00692 would be attached to each of the generally rectangular flat portions 68 on the frustoconical contour of the mounting surface 26. Thus, the magnets 70 are fixedly attached and p~sitioned on the shaft 24. The shaft 24 5 with the magnets 70 attached thereto and the arcuate ~-~
surface 76 of the magnets 70 are formed, such as by grinding, to have a generally frustoconical outer configuration. As best shown in FIGS. 1, 2, 4 and 5, the forming process results in the magnets 70 nearest the end having the larger diameter of the frustoconical outer configuration to have a thickness which is less than the thickness of the magnets 70 near the end of the smaller diameter of the - frustoconical outer configuration. The preestablished inner frustoconical surface 82 of the cover 80 is slightly smaller than and generally matches the frustoconical outer configuration of the formed arcuate surfaces 76 of the magnets 70. Using a proper lubricati~n which is applied to the arcuate surfaces 76 of the magnets 70, the cover 80 is pressed over the magnets 70 until the ends are generally aligned with the ends of the magnets 70. The sleeve 80 is pushed axially over the frustoconical shaft until a predetermined diameter of the sleeve has increased its diameter by an amount which will yield the prescribed prestress required in the sleeve. The tapered rotor makes this press-fit assembly possible. After assembly, the ends of the cover 80 can be trimmed if necessary. Thus, after the cover 80 and the shaft 24 with the magnets 70 attached thereto are assembled, a predetermined prestress will exist between the cover 80 and the magnets 70. The above described assembly procedure provides the rotor assembly 16 with the structural integrity to operate at the desired speed.
Variations in the thickness of the cover 80 as well as ~-5 ~
W094/~203 PCT~S94/00692 material selection for material properties can produce a variety of prestress conditions to operate in any given operating environment. After the cover 80 has been secured to the magnets 70, the end flanges 30 are heated and pressed onto the shaf-t 2 4 . To pre~ent relative movement between parti~ suitable locking of , the end flange 30 can be acc~plished by sta~ing, lock ¦ pins or other means. If the`integral shaft 24 and end flange 30 is use, only one end flange is pressed onto the shaft.
i Industrial Applicability In operation, the rotor assembly 16 is assembled within the outer case 12 and the electric machine lO is ready for operation. The electric machine lO will be described as functioning as a generator for descriptive purposes only.
A demand for electrical energy is sent to the generator. The rotor assembly 16 is driven by an external source and is rotated. The permanent magnets 70 on the rotor assembly 16 are caused to rotate , within the outer case 12 which includes the stator ¦ assembly and produces an electrical current as ¦ periodic variation of the flux of the magnetic lines ¦ 25 of force passing through the loop causes a flow of ¦ electrical current.
As a higher demand for electrical energy is xequired, the speed of rotation of the rotor assembly 16 is increased. The structural arrangement of the rotor assembly 16 allows the speed to increase and the force caused by centrifugal action to be resisted.
For example, as the speed increases the permanent magnets 70 attempt to lift or become separated from the shaft 24. The prestresses within the rotor - 35 assembly 16 resist these forces. The cover 80 213 3 6 4 0 PCT~S94/00692 confines the radial movement of the magnets 70 and the cover exert the prestress or force on the magnets 70 to further retain the contact between the generally rectangular flat portions 68 on the shaft and flat rectangular base surface 72 on the permanent magnets 70. Thus, the operating mode of the high speed generator can be functionally attained with the structural relationship of the rotor assembly 16 A further modification to the rotor assembly 16 has increased the efficiency during operation of the generator. For example, the magnets 70 have the preestablished thickness at the larqer diameter of the frustoconical outer configuration which is less than the preestablished thickness at the smaller diameter.
The results of the varying thickness being that the flux density at the larger diameter is less than the flux density at the smaller diameter. With the frustoconical configuration of the rotor assembly 16, a higher flux density is needed to span between the rotor assembly 16 and the outer case 12.
As an alternative, although not as efficient, the thickness of the magnets 70 could be unif orm.
The assembly of the rotor assembly 16 has greatly reduced the cost of manufacturing and reduced the number of piece parts required to make up the rotor assembly 16. For example, the frustoconical surface 26 on the shaft 24 with the magnets 70 attached thereto and ground to a frustoconical shape and the assembly of the cover 80 about the magnets 70 can be done quicker, more reliably and without expending as much energy. The convention steps of cooling the shaft 24 with the magnets 70 attached thereto and the heating of the cover 80 are eliminated. The frustoconical shape of the mounting surface 26 and the frustoconical contour of the .
,.. . ........ ..
The frustoconical contour has a preestablished taper which, in this application, is between about 1 to 2 degrees .
In this application, the rotor assembly 16 further includes an expander turbine 40 formed as a part of one of the end flanges 30. As best shown in ~133640 FIG. 1 and in the top portion of FIGS. 2 and 5, the expander turbine 40 and the end flange 30 are ~ integral. As an alternatiYe best shown in the bottom ~; portion of FIG. 2, the expander turbine 40 and the end l;
flanges 30 can be separate pieces which are pressed onto the shaft 24. As a further alternative best shown in the bottom portion of FIG. 5, the end flange 30 can be integral with the shaft 24 and the expander ~; ~ turbine 40 can be a separate piece which is pressed - 10 onto the shaft 24.
As further shown in FIG. 3, the frustoconical contour of the mounting surface 26 includes a plurality of generally rectangular flat portions 68. In this application, eight (8) flat portions are used. Each of the generally rectangular flat portions 68 has a length which extends between the end flanges 30 and has a preestablished width. A !.
permanent magnet 70 is attached to each of the flats using a glue having the characteristics of being pliable and non-hardening at low temperatures, such as a room temperature vulcanizing material such as Armstrong A 12 adhesive.
As an alternative, the magnets could be energizable rather than being permanent magnets 70 without changing the gist of the invention. In this application as best shown in FIG. 3, each of the magnets 70 has a flat rectangular base surface 72 defined thereon which is attached to respective rectangular flat portions 68 of the frustoconical contour of the mounting surface 26. A cross-section of each magnet 70 includes the base surface 72, a pair of sides 74 extending theref-om and an arcuate surface 76 connected between the pair of sides 74. In the assembled position, a gap 78 is formed between respective sides 74 of adjacent magnets 70. The .~:
W094/2~03 PCT~S94/00692 ";~
'~133640 magnets 70, when attached to the flat portion 68, are each in contact with the adjacent magnets 70 at the junctures between the sides 74 and the base surfa e 72. As an alternative, a small gap could be provided between corresponding sides 74 o,f~adjacent magnets 70.
If the gap exists it will be filled with glue such as Armstrong A 12. Positioned about the arcuate surface 76 of each of the magnets 70 is a non-magnetic cover 80. As an alternative shown in FIG. 5, the rotor assembly 16 could include an integral formed shaft 24 and one of the end flange 30. The second end flange 30 would be a~tached to the integral formed shaft 24 after attachment of the magnets 70 and the cover 80.
In this application, the cover 80 is made-up of a composite material, such as being formed by winding a fiber, such as a carbon fiber in a curable resin such as epoxy resin, circumferentially about a tapered or frustoconical anvil having a preestablished major diameter and a preestablished minor diameter.
The winding about the anvil results in the cover 80 having a preestablished inner frustoconical surface 82. ~he cover 80 has a preestablished length being generally equal to the length of the frustoconical contour of the mounting surface 26 and has a preestablished thickness. As an alternative, the cover 80 could be made of a non-magnetic metal without changing the concept.
As best shown in FIG. 4, the rotor assembly 16 is assembled as follows. The mounting surface 26 of the shaft 24 has Armstrong A 12 applied thereto and each of the magnets 70 are attached to the generally rectangular flat portions 58. As an alternative ea~h of the rectangular base surface 72 of each of the magnets 70 and the mounting surface 26 could have Armstrong A 12 applied thereto and the magnets 70 2133~40 !0941~03 - PCT~S94/00692 would be attached to each of the generally rectangular flat portions 68 on the frustoconical contour of the mounting surface 26. Thus, the magnets 70 are fixedly attached and p~sitioned on the shaft 24. The shaft 24 5 with the magnets 70 attached thereto and the arcuate ~-~
surface 76 of the magnets 70 are formed, such as by grinding, to have a generally frustoconical outer configuration. As best shown in FIGS. 1, 2, 4 and 5, the forming process results in the magnets 70 nearest the end having the larger diameter of the frustoconical outer configuration to have a thickness which is less than the thickness of the magnets 70 near the end of the smaller diameter of the - frustoconical outer configuration. The preestablished inner frustoconical surface 82 of the cover 80 is slightly smaller than and generally matches the frustoconical outer configuration of the formed arcuate surfaces 76 of the magnets 70. Using a proper lubricati~n which is applied to the arcuate surfaces 76 of the magnets 70, the cover 80 is pressed over the magnets 70 until the ends are generally aligned with the ends of the magnets 70. The sleeve 80 is pushed axially over the frustoconical shaft until a predetermined diameter of the sleeve has increased its diameter by an amount which will yield the prescribed prestress required in the sleeve. The tapered rotor makes this press-fit assembly possible. After assembly, the ends of the cover 80 can be trimmed if necessary. Thus, after the cover 80 and the shaft 24 with the magnets 70 attached thereto are assembled, a predetermined prestress will exist between the cover 80 and the magnets 70. The above described assembly procedure provides the rotor assembly 16 with the structural integrity to operate at the desired speed.
Variations in the thickness of the cover 80 as well as ~-5 ~
W094/~203 PCT~S94/00692 material selection for material properties can produce a variety of prestress conditions to operate in any given operating environment. After the cover 80 has been secured to the magnets 70, the end flanges 30 are heated and pressed onto the shaf-t 2 4 . To pre~ent relative movement between parti~ suitable locking of , the end flange 30 can be acc~plished by sta~ing, lock ¦ pins or other means. If the`integral shaft 24 and end flange 30 is use, only one end flange is pressed onto the shaft.
i Industrial Applicability In operation, the rotor assembly 16 is assembled within the outer case 12 and the electric machine lO is ready for operation. The electric machine lO will be described as functioning as a generator for descriptive purposes only.
A demand for electrical energy is sent to the generator. The rotor assembly 16 is driven by an external source and is rotated. The permanent magnets 70 on the rotor assembly 16 are caused to rotate , within the outer case 12 which includes the stator ¦ assembly and produces an electrical current as ¦ periodic variation of the flux of the magnetic lines ¦ 25 of force passing through the loop causes a flow of ¦ electrical current.
As a higher demand for electrical energy is xequired, the speed of rotation of the rotor assembly 16 is increased. The structural arrangement of the rotor assembly 16 allows the speed to increase and the force caused by centrifugal action to be resisted.
For example, as the speed increases the permanent magnets 70 attempt to lift or become separated from the shaft 24. The prestresses within the rotor - 35 assembly 16 resist these forces. The cover 80 213 3 6 4 0 PCT~S94/00692 confines the radial movement of the magnets 70 and the cover exert the prestress or force on the magnets 70 to further retain the contact between the generally rectangular flat portions 68 on the shaft and flat rectangular base surface 72 on the permanent magnets 70. Thus, the operating mode of the high speed generator can be functionally attained with the structural relationship of the rotor assembly 16 A further modification to the rotor assembly 16 has increased the efficiency during operation of the generator. For example, the magnets 70 have the preestablished thickness at the larqer diameter of the frustoconical outer configuration which is less than the preestablished thickness at the smaller diameter.
The results of the varying thickness being that the flux density at the larger diameter is less than the flux density at the smaller diameter. With the frustoconical configuration of the rotor assembly 16, a higher flux density is needed to span between the rotor assembly 16 and the outer case 12.
As an alternative, although not as efficient, the thickness of the magnets 70 could be unif orm.
The assembly of the rotor assembly 16 has greatly reduced the cost of manufacturing and reduced the number of piece parts required to make up the rotor assembly 16. For example, the frustoconical surface 26 on the shaft 24 with the magnets 70 attached thereto and ground to a frustoconical shape and the assembly of the cover 80 about the magnets 70 can be done quicker, more reliably and without expending as much energy. The convention steps of cooling the shaft 24 with the magnets 70 attached thereto and the heating of the cover 80 are eliminated. The frustoconical shape of the mounting surface 26 and the frustoconical contour of the .
,.. . ........ ..
3 ;~ ~ 3 3 6 4 PCT/US94/00692 ` ) arcuate surfaces 76 of the magnets 70 attached thereto and the frustoconical inner surface 82 of the cover 80 retain the ability to stress the cover 80 about the magnets 70 after pressing the~c~over 80 in place. The ,~
integral end flange 30 and the,`'shaft 24 e~iminates the pressing or bolting of the f~ange 30 to the shaft 24 and the pressing of the single end flange 30 to the shaft 24 eliminates the bolting of the flange 30.
The rotor assembly 16 can withstand high speeds and provides an economically acceptable cost for such an assembly. The design allows the cover 80 to be wound in a normal fashion on a tapered mandrel without requiring it to be prestressed. Hence, material scrap and cost compared to prestressed designs is improved. Furthermore, improved reliability of the prestressed design results from the unique structure and preestablished sizing of the ;
--- arcuate surfaces 76 of the magnets 70 and the inner ~ surface 82 of the cover 80. The rotor assembly 16 further provides positive contact pressure preventing lift-off and detachment between the magnets 70 and the shaft 24. The elimination of bolts or fasteners reduces the air resistance during operation of the rotor assembly 16, resulting in increased generator efficiency. Likewise, the tapered rotor configuration improves generator efficiency. The positive assembly further reduces high speed vibrations.
Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, disclosure and the appended claims.
integral end flange 30 and the,`'shaft 24 e~iminates the pressing or bolting of the f~ange 30 to the shaft 24 and the pressing of the single end flange 30 to the shaft 24 eliminates the bolting of the flange 30.
The rotor assembly 16 can withstand high speeds and provides an economically acceptable cost for such an assembly. The design allows the cover 80 to be wound in a normal fashion on a tapered mandrel without requiring it to be prestressed. Hence, material scrap and cost compared to prestressed designs is improved. Furthermore, improved reliability of the prestressed design results from the unique structure and preestablished sizing of the ;
--- arcuate surfaces 76 of the magnets 70 and the inner ~ surface 82 of the cover 80. The rotor assembly 16 further provides positive contact pressure preventing lift-off and detachment between the magnets 70 and the shaft 24. The elimination of bolts or fasteners reduces the air resistance during operation of the rotor assembly 16, resulting in increased generator efficiency. Likewise, the tapered rotor configuration improves generator efficiency. The positive assembly further reduces high speed vibrations.
Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, disclosure and the appended claims.
Claims (20)
1. A rotor assembly (16) comprising:
a shaft (24) having a first end portion (18) and a second end portion (20) and having a frustoconical surface (26) defined thereon interposed the first and second end portions (18,20);
a plurality of magnets (70) being attached to the frustoconical mounting surface (26);
a cover (80) having a preestablished inner frustoconical surface (82) being in contact with the magnets (70); and a pair of end flanges (30) being attached to the shaft (24).
a shaft (24) having a first end portion (18) and a second end portion (20) and having a frustoconical surface (26) defined thereon interposed the first and second end portions (18,20);
a plurality of magnets (70) being attached to the frustoconical mounting surface (26);
a cover (80) having a preestablished inner frustoconical surface (82) being in contact with the magnets (70); and a pair of end flanges (30) being attached to the shaft (24).
2. The rotor assembly (16) of claim 1 wherein said plurality of magnets (70) are secured to the frustoconical mounting surface (26).
3. The rotor assembly (16) of claim 2 wherein said contact of the inner frustoconical surface (82) of the cover (80) with the magnets (70) further secures the magnets (70) in attachment to the shaft (24).
4. The rotor assembly (16) of claim 1 wherein said cover (80) is made of a non-magnetic material.
5. The rotor assembly (16) of claim 1 wherein said magnets (70) have an arcuate surface (76) in contact with the inner frustoconical surface (82) of the cover (80).
6. The rotor assembly (16) of claim 5 wherein said arcuate surface (76) generally matches the preestablished inner frustoconical surface (82) of the cover (80).
7. The rotor assembly of claim 1 wherein said frustoconical mounting surface (26) of the shaft (24) includes a plurality of generally rectangular flat portions (68) and each of said plurality of magnets (70) includes a generally flat rectangular base surface (72) and said generally flat rectangular base surface (72) of the magnets (70) is attached to each of the plurality of generally rectangular flat portions (68) of the frustoconical surface (26) of the shaft (24) using a glue.
8. The rotor assembly (16) of claim 7 wherein said glue is a room temperature vulcanizing material (Armstrong A 12).
9. The rotor assembly (16) of claim 8 wherein said glue has the characteristic of retaining some ductility at low temperatures.
10. The rotor assembly (16) of claim 1 wherein said magnets (70) further include a pair of sides (74) and in the assembled position forming a gap (78) between the adjacent magnets (70).
11. The rotor assembly (16) of claim 10 wherein said gap (78) has a glue positioned therein.
12. The rotor assembly (16) of claim 11 wherein said glue is a room temperature vulcanizing material (Armstrong A 12).
13. The rotor assembly (16) of claim 1 wherein one of said end flanges (30) is integral with the shaft (24).
14. A method of manufacturing a rotor assembly (16) including a shaft (24) having a frustoconical mounting surface (26) defined thereon, a plurality of magnets (70), a cover (80) and a pair of end flanges (30), comprising the steps of;
attaching the plurality of magnets (70) to the frustoconical mounting surface (26) of the shaft (24);
positioning the cover (80) about the plurality of magnets (70); and attaching at least one of the end flanges (30) to the shaft (24).
attaching the plurality of magnets (70) to the frustoconical mounting surface (26) of the shaft (24);
positioning the cover (80) about the plurality of magnets (70); and attaching at least one of the end flanges (30) to the shaft (24).
15. The method of manufacturing a rotor assembly (16) of claim 14 wherein said step of attaching the plurality of magnets (70) to a frustoconical mounting surface (26) of the shaft (24) includes applying a glue to the frustoconical mounting surface (26) and pressuring the glue between the plurality of magnets (70) and the shaft (24).
16. The method of manufacturing a rotor assembly (16) of claim 15 wherein said step of attaching the plurality of magnets (70) to the frustoconical mounting surface (26) of the shaft (24) includes applying a glue to a gap (78) formed between adjacent magnets (70).
17. The method of manufacturing a rotor assembly (16) of claim 14 wherein said step of positioning the cover (80) about the plurality of magnets (70) includes applying a lubrication to the magnets (70).
18. The method of manufacturing a rotor assembly (16) of claim 17 wherein said step of positioning the cover (80) about the plurality of magnets (70) includes prestressing the cover (80) to further attach the plurality of magnets (70) to the shaft (24).
19. The method of manufacturing a rotor assembly (16) of claim 17 wherein said step of positioning the cover (80) about the plurality of magnets (70) includes pressing the cover (80) over the shaft (24) with the magnets (70) attached thereon.
20. The method of manufacturing a rotor assembly (16) of claim 14 wherein said step of attaching the end flanges (30) to the shaft (24) includes heating at least one of the end flanges (30) and pressing said one of the end flanges (30) onto the shaft (24).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/033,483 US5486730A (en) | 1993-03-18 | 1993-03-18 | Rotor assembly |
| US033,483 | 1993-03-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2133640A1 true CA2133640A1 (en) | 1994-09-29 |
Family
ID=21870678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002133640A Abandoned CA2133640A1 (en) | 1993-03-18 | 1994-01-24 | Method and apparatus for manufacturing a rotor assembly |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5486730A (en) |
| EP (1) | EP0641497B1 (en) |
| JP (1) | JPH07507197A (en) |
| CA (1) | CA2133640A1 (en) |
| DE (1) | DE69403589T2 (en) |
| WO (1) | WO1994022203A1 (en) |
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| JP3369024B2 (en) * | 1995-04-14 | 2003-01-20 | 松下電器産業株式会社 | Permanent magnet rotor and its manufacturing method |
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| DE19736710B4 (en) * | 1997-08-18 | 2005-05-25 | Siemens Ag | Rotor for a dynamoelectric machine |
| DE19736295C1 (en) * | 1997-08-21 | 1999-06-02 | Freudenberg Carl Fa | Magnetic system, comprising one or more permanent magnets attached to a carrier body |
| US6145314A (en) * | 1998-09-14 | 2000-11-14 | Turbodyne Systems, Inc. | Compressor wheels and magnet assemblies for internal combustion engine supercharging devices |
| EP0996212A1 (en) * | 1998-10-21 | 2000-04-26 | Technische Universiteit Eindhoven | Method for fabricating a permanent magnet rotor, and rotor obtained by said method |
| US7884522B1 (en) | 2004-10-25 | 2011-02-08 | Novatorque, Inc. | Stator and rotor-stator structures for electrodynamic machines |
| US6777844B2 (en) * | 2000-10-24 | 2004-08-17 | Rexair, Inc. | Brushless motor |
| EP1333558A3 (en) * | 2002-01-31 | 2005-01-26 | Hitachi, Ltd. | Rotor for rotating electric machine and method of fabricating the same, for gas turbine power plant |
| US6492753B2 (en) | 2002-03-08 | 2002-12-10 | Dura-Trac Motors, Inc. | Brushless permanent magnet motor with variable axial rotor/stator alignment to increase speed capability |
| US6943478B2 (en) * | 2003-11-14 | 2005-09-13 | Dura-Trac Motors, Inc. | Brushless permanent magnet wheel motor with variable axial rotor/stator alignment |
| US8471425B2 (en) | 2011-03-09 | 2013-06-25 | Novatorque, Inc. | Rotor-stator structures including boost magnet structures for magnetic regions having angled confronting surfaces in rotor assemblies |
| US8330316B2 (en) | 2011-03-09 | 2012-12-11 | Novatorque, Inc. | Rotor-stator structures including boost magnet structures for magnetic regions in rotor assemblies disposed external to boundaries of conically-shaped spaces |
| US7294948B2 (en) * | 2004-10-25 | 2007-11-13 | Novatorque, Inc. | Rotor-stator structure for electrodynamic machines |
| US8543365B1 (en) | 2004-10-25 | 2013-09-24 | Novatorque, Inc. | Computer-readable medium, a method and an apparatus for designing and simulating electrodynamic machines implementing conical and cylindrical magnets |
| US8283832B2 (en) * | 2004-10-25 | 2012-10-09 | Novatorque, Inc. | Sculpted field pole members and methods of forming the same for electrodynamic machines |
| US9093874B2 (en) | 2004-10-25 | 2015-07-28 | Novatorque, Inc. | Sculpted field pole members and methods of forming the same for electrodynamic machines |
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| US7061152B2 (en) * | 2004-10-25 | 2006-06-13 | Novatorque, Inc. | Rotor-stator structure for electrodynamic machines |
| JP3944505B2 (en) * | 2004-10-26 | 2007-07-11 | 三菱電機株式会社 | Rotating electric machine and manufacturing method thereof |
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| BR112012020378A2 (en) * | 2010-02-16 | 2016-05-10 | Siemens Ag | Method of mounting part of a generator, generator and wind turbine |
| CN102782989B (en) * | 2010-06-10 | 2015-05-20 | 三菱电机株式会社 | Rotating electrical machine rotor |
| JP5679899B2 (en) * | 2011-05-06 | 2015-03-04 | 三菱電機株式会社 | Permanent magnet rotating electric machine |
| US20130028737A1 (en) * | 2011-07-25 | 2013-01-31 | Sports Art Industrial Co., Ltd. | Adjustable wind turbine generating device |
| US8458895B2 (en) | 2011-09-30 | 2013-06-11 | General Electric Company | Assembly for positioning a rotor retaining ring |
| JP5989415B2 (en) * | 2012-06-20 | 2016-09-07 | 信越化学工業株式会社 | Method for assembling cylindrical magnetic circuit |
| JP5689550B2 (en) | 2013-04-03 | 2015-03-25 | ファナック株式会社 | Rotor member fixed to rotating shaft portion of rotating electric machine, rotor provided with rotor member, rotating electric machine, and method of manufacturing rotor |
| RU2689314C1 (en) * | 2016-04-07 | 2019-05-27 | Мейденся Корпорейшн | Rotor with permanent magnet for rotating electrical machine |
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| DE102017103027A1 (en) * | 2017-02-15 | 2018-08-16 | Rausch & Pausch Gmbh | LINEAR |
| JP6730233B2 (en) * | 2017-07-26 | 2020-07-29 | ファナック株式会社 | Rotor, rotating electric machine, and method for manufacturing rotor |
| CN113678343A (en) * | 2019-04-10 | 2021-11-19 | 株式会社Ihi | Motor rotor |
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| US4918802A (en) * | 1989-02-06 | 1990-04-24 | Franklin Electric Co., Inc. | Method and apparatus for making permanent magnet rotors |
-
1993
- 1993-03-18 US US08/033,483 patent/US5486730A/en not_active Expired - Fee Related
-
1994
- 1994-01-24 DE DE69403589T patent/DE69403589T2/en not_active Expired - Fee Related
- 1994-01-24 EP EP94906689A patent/EP0641497B1/en not_active Expired - Lifetime
- 1994-01-24 JP JP6521014A patent/JPH07507197A/en active Pending
- 1994-01-24 CA CA002133640A patent/CA2133640A1/en not_active Abandoned
- 1994-01-24 WO PCT/US1994/000692 patent/WO1994022203A1/en active IP Right Grant
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994022203A1 (en) | 1994-09-29 |
| JPH07507197A (en) | 1995-08-03 |
| DE69403589T2 (en) | 1998-01-22 |
| DE69403589D1 (en) | 1997-07-10 |
| EP0641497B1 (en) | 1997-06-04 |
| US5486730A (en) | 1996-01-23 |
| EP0641497A1 (en) | 1995-03-08 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |