CA1094621A - Axial electromagnetic bearing - Google Patents
Axial electromagnetic bearingInfo
- Publication number
- CA1094621A CA1094621A CA294,749A CA294749A CA1094621A CA 1094621 A CA1094621 A CA 1094621A CA 294749 A CA294749 A CA 294749A CA 1094621 A CA1094621 A CA 1094621A
- Authority
- CA
- Canada
- Prior art keywords
- disc
- armature
- bearing
- grooves
- fixed
- 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.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
- F16C32/0406—Magnetic bearings
- F16C32/044—Active magnetic bearings
- F16C32/0474—Active magnetic bearings for rotary movement
- F16C32/0476—Active magnetic bearings for rotary movement with active support of one degree of freedom, e.g. axial magnetic bearings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
- F16C32/0406—Magnetic bearings
- F16C32/044—Active magnetic bearings
- F16C32/0459—Details of the magnetic circuit
- F16C32/0468—Details of the magnetic circuit of moving parts of the magnetic circuit, e.g. of the rotor
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Magnetic Bearings And Hydrostatic Bearings (AREA)
- Electromagnets (AREA)
Abstract
ABSTRACT
An axial electromagnetic bearing for supporting the end of a shaft rotating at high speed of the type comprising an armature in the form of a disc attached to the shaft and a fixed annular armature disposed facing the disc armature a short distance from the former so as to define a small axial air gap therebetween, the said fixed armature comprising excitation windings and a ferromagnetic core, the bearing being characterised in that radial grooves are provided in the peripheral portion of the disc and situated facing the annular fixed armature.
The arrangement causes a reduction in the effect of Eddy currents without detracting from the mechanical strength of the bearing.
An axial electromagnetic bearing for supporting the end of a shaft rotating at high speed of the type comprising an armature in the form of a disc attached to the shaft and a fixed annular armature disposed facing the disc armature a short distance from the former so as to define a small axial air gap therebetween, the said fixed armature comprising excitation windings and a ferromagnetic core, the bearing being characterised in that radial grooves are provided in the peripheral portion of the disc and situated facing the annular fixed armature.
The arrangement causes a reduction in the effect of Eddy currents without detracting from the mechanical strength of the bearing.
Description
~a~ 4~
The present inven-tion to an elec-tromagnetic bearing for supporting the ends of rotors rota-ting at high speeds of the type which cornprises a disc armature integral wi-th the rotor and an annular fixed armature located a-t a sma].l dlstance from the disc armature in such a manner -that a small axial air gap is formed, -the said fixed armature comprising exication windings and a ferromagnetic coreO
The mounting of a shaft rotating with the assistance of axial an~/or radial electromagnetic suspension has a number of advantages in that frietion is suppressed and the inertia and the rigidity of the shaft ean be increased since the eleetromagnetic suspension is not affected by the diameter of the shaft.
Aecordingly, vibration is redueed at high speedsO In addition, the eontrol of electromagnetic bearlngs with the help of detectors for the positioning of the shaft enablesthe shaft to be maintained in position against axial and/or radial displacement forces.
~ he operation of axial eleetromagnetic beariIlgs poses, however, a certain number of problemsO In effeet, the dise armature, whieh eonstitutes the rotor of the bearing, rotates at a very high speed and cannot be made of a laminated material because the meehanieal strength would be too weak. Aeeordingly, large Eddy eurrents are in~ueed in the interior of the body of the disc and these eause damping which lead to a limita-tion in the pass band of the associated eontrol.
It has been proposed, to reduce -the size of the Eddy currentc;
that radial slots be eut in -th~ periphery of the disc in the form of teethO Such an arrangement eertainly reduees ~ddy currents but the cllt-away portions lead to.too great a reduction in '' :~0~ 2~L
the mechanical strength. In effect, at high ro-tational speeds, the exagera-ted stress appearing at the root of -the teeth can cause rup-turing of the disc.
The object of the present invention is to remedy the aforementioned inconveniences and notably to reduce the Eddy currents appearing in the disc of an axial elec-tromagnetic bearing without causing a notable diminution of the mechanical strength of the said disc.
~ ccording to the present invention there is provided an axial electromagne ic bearing for supporting the end of a - shaf-t rotating at high speed comprising an armature in the form of a disc attached to the shaft and an annular fixed armature located a short distance from the disc to define a small axial air gap therebetween, the said fixed armature comprising excitation windings and a ferromagnetic core, and the bearing bearing characterised in that radial grooves are provided in the peripheral portion of the disc armature facing the fixed armature.
Thus, these radial yrooves cut the Eddy currents from --which it follows that the damping and thus the weakening of the control of the axial bearing are reduced. Moreover, the mechan-ical strength of the disc integral with the rotating shaft magnetically s~spended is not substantially reduced and the disc can withstand high rotational speeds. In effect, the thickness of the disc is reduced in localised zones but there is no discontinuity in the edge of the disc.
Preferably, the said grooves are regularly spaced in the said peripheral portion of the disc armature.
In one particular emhodiment of the invention, when the 3~ .
axial bearing comprises a disc armature disposed between two fixed annular armatures, the radi.al grooves are provided in the two aces of the disc i.n the peripheral portion thereof faci.ng the annular armatures.
Preferably, the radial grooves provided i.n each of the faces of the disc are regularly spaced arld out ~f phase in relation to the grooves provided in the opposite face of the disc.
Preferably also, each groove in each face of the disc is disposed an equal distance from the two nearest grooves situated on the opposite face of the disc.
The grooves permit a maximum efficiency to be attained when they are out of phase by a half cycle, that is to say when each groove on one face of the disc is diametrically opposite to a groove on the other side of the disc.
The preserit invention will now be described by way of exa~ple with reference to the accompanying drawing in which:-Fig. 1 is a cross section on the line I-I of ~igure 2 showing a bearing according to thé invention; and Fig. 2 is a side view of a disc forming the rotor armature of -the axial bearing of ~igure 1.
As can be seen in ~igure 1, a disc 1 comprises the rotor armature of an electromagnetic axial ~earlng. ~he disc 1 is located between two annular stator armatures 2 and ~ comprising repsectively a ferromagnetic core 2a, ~ and excitation windings 2b1 3b. The disc 1, integral with a rotating shaft 8, has two frorlt faces 6 and 7 and an end face 9. Grooves 4 and 5 respectively are provided in the faces 6 and 7 of the disc 1 in the peripheral porti.on thereof situa~ed facing -the annular stator armatures 2 arid 3 respectively7 As can be seen in Figure 2, 6Z$
the radial grooves 4, 5 respectively are regularl~ spaced at the periphery of the disc 1 and -the grooves in one of the faces are out of phase in relation to the grooves provided in the opposite face. Preferabl~, each groove 4, 5 on each face 6, '7 of the disc 'l is located an equal distance from two grooves 5, 4 which are situated the nearest to it on the opposite face 7, 6 respectively.
As sho~Jn in Figure 1, each groove 4, 5 respectively of a face 6, 7 respectively of the disc 1 is diame-trically opposite a grQove 5, 4 respectively on the opposite face 7, 6 of the disc 1 Thus, the grooves of one of the faces are out of phase b~r a half-cycle in relation to the grooves of the other face.
~ he rin~s 2a, 3a comprising the ferromagnetic core of the stator armature 27~ and which are coaxial to the shaft 8 Cc~l be made in one piece but are preferably made of bundles of isolated laterall~ disposed sheets or of laminated iron sheets in order to reduce the heating of the electromagnetic portions and ~he loss caused by Eddy currents, The air gaps 10 and 11 between t-he stator armatures 2 and 3 respectively and the disc armature 1 of the axial electromagnetic bearin~ are controlled and regulated with the help of axial detectors, not shown, in relation to the axial position of the shaft 8. '~hese axial dete,c-tors regulate the excita-tion of the axial bearing in such a manner as to maintain constantly the air gaps lQ and 11.
'l`he disc 1 can be formed with an aperture ~2 at its centre and be moun-ted coaxially on -the shaft 8, as shown in ~igures 1 and 2, or can comprise an abutment on the shaft 8 in the fashion of -the horizontal cxoss-piece of a 'l1-shape~
' , .
It is to be noted that, in accordance wi-th the present invention~ the end face 9 of the disc 1 is not cu-t and always has a thicknc~ss or width A. ~he thickness of the disc 1 is only reduced at the ].evel of the grooves 4 and 5 with respect to the end face 9 of -the disc 1. The grooves 4 and 5 can have different configurations but advantageously the profile of the bottom 14, 15 of the grooves 4, 5 is curved so tha-t the forming of the grooves is facilitated and the efficiency can be the greatest possible with relation to a removal of the least material and so that the profile of the grooves can correspond substantially to the field lines of the induced magnetic field.
As is well known, diverse modification and additions can be made by persons skilled in the art to the apparatus which is described above strictly by way of non--limiting example without limiting the scope of protection of the invention.
The present inven-tion to an elec-tromagnetic bearing for supporting the ends of rotors rota-ting at high speeds of the type which cornprises a disc armature integral wi-th the rotor and an annular fixed armature located a-t a sma].l dlstance from the disc armature in such a manner -that a small axial air gap is formed, -the said fixed armature comprising exication windings and a ferromagnetic coreO
The mounting of a shaft rotating with the assistance of axial an~/or radial electromagnetic suspension has a number of advantages in that frietion is suppressed and the inertia and the rigidity of the shaft ean be increased since the eleetromagnetic suspension is not affected by the diameter of the shaft.
Aecordingly, vibration is redueed at high speedsO In addition, the eontrol of electromagnetic bearlngs with the help of detectors for the positioning of the shaft enablesthe shaft to be maintained in position against axial and/or radial displacement forces.
~ he operation of axial eleetromagnetic beariIlgs poses, however, a certain number of problemsO In effeet, the dise armature, whieh eonstitutes the rotor of the bearing, rotates at a very high speed and cannot be made of a laminated material because the meehanieal strength would be too weak. Aeeordingly, large Eddy eurrents are in~ueed in the interior of the body of the disc and these eause damping which lead to a limita-tion in the pass band of the associated eontrol.
It has been proposed, to reduce -the size of the Eddy currentc;
that radial slots be eut in -th~ periphery of the disc in the form of teethO Such an arrangement eertainly reduees ~ddy currents but the cllt-away portions lead to.too great a reduction in '' :~0~ 2~L
the mechanical strength. In effect, at high ro-tational speeds, the exagera-ted stress appearing at the root of -the teeth can cause rup-turing of the disc.
The object of the present invention is to remedy the aforementioned inconveniences and notably to reduce the Eddy currents appearing in the disc of an axial elec-tromagnetic bearing without causing a notable diminution of the mechanical strength of the said disc.
~ ccording to the present invention there is provided an axial electromagne ic bearing for supporting the end of a - shaf-t rotating at high speed comprising an armature in the form of a disc attached to the shaft and an annular fixed armature located a short distance from the disc to define a small axial air gap therebetween, the said fixed armature comprising excitation windings and a ferromagnetic core, and the bearing bearing characterised in that radial grooves are provided in the peripheral portion of the disc armature facing the fixed armature.
Thus, these radial yrooves cut the Eddy currents from --which it follows that the damping and thus the weakening of the control of the axial bearing are reduced. Moreover, the mechan-ical strength of the disc integral with the rotating shaft magnetically s~spended is not substantially reduced and the disc can withstand high rotational speeds. In effect, the thickness of the disc is reduced in localised zones but there is no discontinuity in the edge of the disc.
Preferably, the said grooves are regularly spaced in the said peripheral portion of the disc armature.
In one particular emhodiment of the invention, when the 3~ .
axial bearing comprises a disc armature disposed between two fixed annular armatures, the radi.al grooves are provided in the two aces of the disc i.n the peripheral portion thereof faci.ng the annular armatures.
Preferably, the radial grooves provided i.n each of the faces of the disc are regularly spaced arld out ~f phase in relation to the grooves provided in the opposite face of the disc.
Preferably also, each groove in each face of the disc is disposed an equal distance from the two nearest grooves situated on the opposite face of the disc.
The grooves permit a maximum efficiency to be attained when they are out of phase by a half cycle, that is to say when each groove on one face of the disc is diametrically opposite to a groove on the other side of the disc.
The preserit invention will now be described by way of exa~ple with reference to the accompanying drawing in which:-Fig. 1 is a cross section on the line I-I of ~igure 2 showing a bearing according to thé invention; and Fig. 2 is a side view of a disc forming the rotor armature of -the axial bearing of ~igure 1.
As can be seen in ~igure 1, a disc 1 comprises the rotor armature of an electromagnetic axial ~earlng. ~he disc 1 is located between two annular stator armatures 2 and ~ comprising repsectively a ferromagnetic core 2a, ~ and excitation windings 2b1 3b. The disc 1, integral with a rotating shaft 8, has two frorlt faces 6 and 7 and an end face 9. Grooves 4 and 5 respectively are provided in the faces 6 and 7 of the disc 1 in the peripheral porti.on thereof situa~ed facing -the annular stator armatures 2 arid 3 respectively7 As can be seen in Figure 2, 6Z$
the radial grooves 4, 5 respectively are regularl~ spaced at the periphery of the disc 1 and -the grooves in one of the faces are out of phase in relation to the grooves provided in the opposite face. Preferabl~, each groove 4, 5 on each face 6, '7 of the disc 'l is located an equal distance from two grooves 5, 4 which are situated the nearest to it on the opposite face 7, 6 respectively.
As sho~Jn in Figure 1, each groove 4, 5 respectively of a face 6, 7 respectively of the disc 1 is diame-trically opposite a grQove 5, 4 respectively on the opposite face 7, 6 of the disc 1 Thus, the grooves of one of the faces are out of phase b~r a half-cycle in relation to the grooves of the other face.
~ he rin~s 2a, 3a comprising the ferromagnetic core of the stator armature 27~ and which are coaxial to the shaft 8 Cc~l be made in one piece but are preferably made of bundles of isolated laterall~ disposed sheets or of laminated iron sheets in order to reduce the heating of the electromagnetic portions and ~he loss caused by Eddy currents, The air gaps 10 and 11 between t-he stator armatures 2 and 3 respectively and the disc armature 1 of the axial electromagnetic bearin~ are controlled and regulated with the help of axial detectors, not shown, in relation to the axial position of the shaft 8. '~hese axial dete,c-tors regulate the excita-tion of the axial bearing in such a manner as to maintain constantly the air gaps lQ and 11.
'l`he disc 1 can be formed with an aperture ~2 at its centre and be moun-ted coaxially on -the shaft 8, as shown in ~igures 1 and 2, or can comprise an abutment on the shaft 8 in the fashion of -the horizontal cxoss-piece of a 'l1-shape~
' , .
It is to be noted that, in accordance wi-th the present invention~ the end face 9 of the disc 1 is not cu-t and always has a thicknc~ss or width A. ~he thickness of the disc 1 is only reduced at the ].evel of the grooves 4 and 5 with respect to the end face 9 of -the disc 1. The grooves 4 and 5 can have different configurations but advantageously the profile of the bottom 14, 15 of the grooves 4, 5 is curved so tha-t the forming of the grooves is facilitated and the efficiency can be the greatest possible with relation to a removal of the least material and so that the profile of the grooves can correspond substantially to the field lines of the induced magnetic field.
As is well known, diverse modification and additions can be made by persons skilled in the art to the apparatus which is described above strictly by way of non--limiting example without limiting the scope of protection of the invention.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An axial electromagnetic bearing for supporting the end of a shaft rotating at high speed comprising an armature in the form of a disc attached to the shaft and an annular fixed armature located a short distance from the disc to define a small axial air gap therebetween, the said fixed armature comprising excitation windings and a ferromagnetic core, and the bearing being characterised in that radial grooves are provided in the peripheral portion of the disc armature facing the fixed armature.
2. A bearing as claimed in claim 1, characterised in that the said grooves are regularly spaced in the said peripheral portion of the disc armature.
3. A bearing as claimed in claim 1, in which the disc armature is disposed between two fixed annular armatures, characterised in that the radial grooves are provided in the two faces of the disc in the peripheral portion of the disc facing the fixed armatures.
4. A bearing as claimed in claim 3, characterised in that the radial grooves provided in each of the faces of the disc are regularly spaced and out of phase in relation to the grooves provided in the opposite face of the disc.
5. A bearing as claimed in claim 4, characterised in that each groove in each face of the disc is disposed an equal distance from the two nearest grooves situated on the opposite face of the disc.
6. A bearing as claimed in Claim 5 characterised in that each groove of one face of the disc is diametrically opposed to a groove in the opposite face of the disc.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7700767A FR2377550A1 (en) | 1977-01-12 | 1977-01-12 | AXIAL ELECTROMAGNETIC BEARING |
| FR7700767 | 1977-01-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094621A true CA1094621A (en) | 1981-01-27 |
Family
ID=9185404
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA294,749A Expired CA1094621A (en) | 1977-01-12 | 1978-01-11 | Axial electromagnetic bearing |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5912886B2 (en) |
| CA (1) | CA1094621A (en) |
| DE (1) | DE2801040C2 (en) |
| FR (1) | FR2377550A1 (en) |
| GB (1) | GB1542798A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3740295A1 (en) * | 1987-11-27 | 1989-06-08 | Asea Brown Boveri | AXIAL MAGNETIC BEARING |
| JP2001234929A (en) * | 2000-02-21 | 2001-08-31 | Ebara Corp | Magnetic bearing and circulation fan device |
| DE102009017355B4 (en) * | 2009-04-14 | 2011-09-01 | Continental Automotive Gmbh | Actively controlled axial magnetic bearing |
| JP7303503B2 (en) * | 2019-03-01 | 2023-07-05 | 国立大学法人埼玉大学 | magnetic levitation pump |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3929390A (en) * | 1971-12-22 | 1975-12-30 | Cambridge Thermionic Corp | Damper system for suspension systems |
-
1977
- 1977-01-12 FR FR7700767A patent/FR2377550A1/en active Granted
- 1977-12-29 GB GB5421177A patent/GB1542798A/en not_active Expired
-
1978
- 1978-01-10 JP JP53001836A patent/JPS5912886B2/en not_active Expired
- 1978-01-11 CA CA294,749A patent/CA1094621A/en not_active Expired
- 1978-01-11 DE DE19782801040 patent/DE2801040C2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1542798A (en) | 1979-03-28 |
| FR2377550A1 (en) | 1978-08-11 |
| DE2801040C2 (en) | 1985-04-04 |
| DE2801040A1 (en) | 1978-07-20 |
| JPS5912886B2 (en) | 1984-03-26 |
| FR2377550B1 (en) | 1979-04-20 |
| JPS5388443A (en) | 1978-08-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |