CA1298605C - Rotor assembly and motor construction and method of making same - Google Patents
Rotor assembly and motor construction and method of making sameInfo
- Publication number
- CA1298605C CA1298605C CA000550129A CA550129A CA1298605C CA 1298605 C CA1298605 C CA 1298605C CA 000550129 A CA000550129 A CA 000550129A CA 550129 A CA550129 A CA 550129A CA 1298605 C CA1298605 C CA 1298605C
- Authority
- CA
- Canada
- Prior art keywords
- rotor
- stack
- laminations
- stator
- tension rod
- 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 - Lifetime
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
-
- 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
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/32—Correcting- or balancing-weights or equivalent means for balancing rotating bodies, e.g. vehicle wheels
- F16F15/322—Correcting- or balancing-weights or equivalent means for balancing rotating bodies, e.g. vehicle wheels the rotating body being a shaft
-
- 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
- H02K1/28—Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures
-
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K19/00—Synchronous motors or generators
- H02K19/02—Synchronous motors
- H02K19/10—Synchronous motors for multi-phase current
- H02K19/103—Motors having windings on the stator and a variable reluctance soft-iron rotor without windings
Abstract
Abstract of the Disclosure A rotor assembly for an electric motor includes a plurality of laminations disposed in a stack, a tension rod extending axially through the rotor lamination stack, and end clamps disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position on by compression. A
method of stamping rotor and stator laminations for a doubly salient electric motor from a single piece of metal includes the steps of stamping a rotor lamination out of the piece of metal, and stamping the stator lamination out of the piece of metal offset from the stamping o the rotor lamination 80 that a tooth of the rotor lamination stamping is taken from the gap between two teeth of the stator lamination stamping. The centroids of the rotor and stator laminations in their stamped locations in the piece of metal are offset from one another.
method of stamping rotor and stator laminations for a doubly salient electric motor from a single piece of metal includes the steps of stamping a rotor lamination out of the piece of metal, and stamping the stator lamination out of the piece of metal offset from the stamping o the rotor lamination 80 that a tooth of the rotor lamination stamping is taken from the gap between two teeth of the stator lamination stamping. The centroids of the rotor and stator laminations in their stamped locations in the piece of metal are offset from one another.
Description
36~i This invention relates to eleGtric motors and more particularly ~o constructions and methods of construction thereof.
Switched reluctance motors have attracted considerable attention over the past ten to ~ifteen years, primarily due to the simplicity of their construction and high power densities ~ratio between output power and weight), These motors are doubly ~alient motor~, having eeth on both the stator and the rotor, with phase windings only on the stator poles.
~xcept for very small (below 50 watt) motors, most switched reluctance motors are desiyned to operate below 2000 RPM
because the core losse~ in switched reluctance motors are several time~ l~rger than in conventional machines of ~he same size. ~or that r~ason, ~onven~ional wisdom is that switched reluctance motor~ ~re best suited for low speed applications. Of course ce~tain applications such as air cooling compressor motorY are required ~o operate at much higher speeds, such as 5000 RPM.
Early switched reluctance motors for larger power levels had six poles on the stator and four on tbe rotor. To reduce the number o~ power switches equired to supply power to these ~oto~, later design~ adopted an 8/4 construction (eight s~ator poles and four rotor poles), which required fewer power switches and.h~d improved starting torque.
" ~L29861r)5 0963B 1/16/87 DN349g E-1093 In order to limit the core losses ln prior machines, the direction of the stator magneto-motive ~orce (mmf~ was selected in ~u~h a way that the mmf direction ~n the rotor changed only once per full rotor revolution. In ~his way, the high frequency ~lux changes, which are proportional to the number of rotor poles, appeared only in the stator poles and the edges of the rotor poles. As a result, the core losses in the stator yoke and rotor core were reduced at the expense of some torque imbalance.
Of greater concern are the losses in the stator poles due to Elux bypass with such a construction. This bypass flux produces a torque in ~he opposite direction, and the bypass mmf has the opposite direction ~rom the main mmf to be e~tablished when the next phase is energi~ed. This change in the mmf direction in the stator poles of prior motors increased the ran~3e of flux variatlon and lead to increased core losses in stator poles.
In addition to the normal losse~ due to eddy currents and hysteresis, core losses are also affe~ted by the method conventionally used in stamping the rotor and stator lamin~tions. Stamping the laminations for conventional machines i done as follows: Fir ~ the stator ands rotor slots are stamped out ~nd then the rotor lamination i~ stamped from the stator lamination. ~s a result, bo~h stator and rotor teeth are sharply rectangular.
~IILZ~6l~5 Apparently the laminations or switched reluctance motors up to now have been made in the same way. As a result, the stator and rotor poles or teeth have sharp, rectangular corner~. Since switched reluctance motors have only one tooth per pole and s~nce they operate on the attraction between teeth/poles, there is a very strong flux concentration at the corners of each pole, pri~r to and after the alignment of the ~tator and rotor poles, resulting in increased losses. Rounding of these corners would, on the other hand, appear to regulre a new method o~ lamination stamping.
Furthermore, the stamping method presently used on conventional machines requires final machining of the rotor sur~ce, to obtain the exac~ rotor diameter. This machining normally results in short circulting of ~ome of the rotor lami~ations, as does the welding used to hold the laminations together. Although the frequency of the rotor flux in induction machines is low, this manufacturing method and the resulting short-circuiting of lamlnations cause~ additional losses which may amount to several percent of the total losses. In switched reluctance motors the machining necessary~to obtain the exact rvtor diameter would considerably increase ~he total losses given the frequen~y change o~ the r~t~r flux variations.
~ inally, large leakage flux when the rotor is in the po~itlon o~ maximum magnetic relu~tance results in ~lux line~
p~rpendicular to the rotor and stator surfaces. Rectangular poles make the flux lines longer, further increasing the losses.
~L~9860~; -For the above reasons, most of the ~witched reluctance motors used up to now have high quality laminations, with a thickness of 0.014~, which is smaller than in conventional machines. Furthermore, in order to reduce vibrations caused by the ~trong changes in mmf, present sw~tched reluctance motors have rotor lamination assemblie~ which are bonded together by adhesives.
Reducing the number of rotor poles i~ advantageous in designing switched reluctance motors for operation at higher ~peeds. However with conventional rotor construction, it i~ not Eeasible to reduce the number of rotor poles ~elow four. Even with four poles, the ~lux density (and thus the los es) is high due to the opening in the lamination stack for the motor shat, wh~ch decreases the effective cro~s-section of the rotor core.
For example, a three-pole rotor in a switched reluctance ~otor has no room for a conventional shaft if the ~lux density in the rotor core i8 to be held at ~n acceptable level. At the ~ame t~me, due to the odd number o rotor pole~, the radial force~
with a three-pole rotor are very large and unbalanced, reyuiring an even larger shaft than normal. These ~ery strong one-directional radial forces require an exceptionally ~tiff r~tor construction.
~Z9~605 Summary of the Inventlon Among the features of the present invention may be noted the provision of a motor with high speed, high horsepower and acceptable core losses.
The present invention also provides improved stator and rotor laminations with reduced losses.
A third object of the present invention is the provision of an improved rotor assembly and motor construction which eliminates the final machining and associated short circuiting of the rotor laminations.
A fourth object of the present invention is the provision of an improved rotor assembly and motor construction that eliminates the need to bond the rotor laminations.
A fifth object of the present invention is the provision of an improved rotor assembly construction which withstands large, unbalanced radial forces.
; Other objects and features will be in part apparent and in part point~d out hereinafter.
Briefly, an electric motor of the present invention has a stator with an axial bore therethrough, a rotor having an axis of rotation mounted for rotation about that axis of rotation in the bore of the stator, said rotor comprising a plurality of laminations disposed in a stack, the improvement comprising a tension rod extending axially through the rotor lamination stack and means disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position by compression, said laminations being unbonded with respect to each other, the compressing means including end clamps disposed at each end of the stack, the laminations having a plurality of teeth, the end clamps having a footprint corresponding to the shape of the laminations.
lZ~
The invention also involvss a rotor assembly for an electric motor having a stator with an axial bore therethrough, said rotor assembly having an axis of rotation and being mountable for rotation about said axis of rotation in the bore of the stator, comprising:
a plurality of laminations disposed in a stack;
a tension rod extending axially through the rotor lamination stack; and means disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position by compression, said laminations being unbonded with respect to each other;
the compressing means including end clamps disposed at each end of the stack, the laminations having a plurality of teeth, the end clamps having a footprint corresponding to the shape of the laminations.
Also, the invention concerns a method of constructing a rotor assembly comprising the steps of:
forming a plurality of rotor laminations each of which has a plurality of teeth;
orienting the plurality of rotor laminations to form a stack;
forming end clamps having footprints corresponding to the shape of the laminations;
fixedly securing an end clamp on each end of the stack to a tension rod extending through the stack to maintain compression of the stack; and machining the rotor laminations to their final dimensions after the tension rod is secured thereto.
36()5 Brief Description of ~he Drawlngs Fig. 1 is a ~chema~ic illustration of a motor made in accordance with the present invention;
Flg. 2 is a schematic illustration similar to Fig. 1, but on a reduced SGale, illustrating the direction o~ the mmf and the flow of flu~ in the motor of Fig. l;
Fig. 2A is an electrical schematic illustrating a converter circuit for the motor of Fig. l;
Fig. 3 is a simplified elevation illustrating the construction of the motor of Fig. l;
Fig. 4 i~ an elevation, with parts broken away for clarity, of the motor of Fig. l;
F19. 5 is a bottom plan of an end clamp used in the motor of Fig. l;
Fig. 5A is a side elevation, with parts broken away for clarity, of the end clamp of ~ig. 5;
Fig. 6 is a bot~om plan of a second embodiment of an end clamp used w~th the motor of Fig. l;
l~ S
0963B 1/16/87 DN34gg E-1093 Fig. 6~ is a cross-sectional view taken along line 6A --6A oiE Fig . 6;
Fig. 7 is a schematic illustration of the stamping patt~rn for ~he rotor and stator laminations of the motor of Fig.
s and Fig. 7A is a diagrammatic representation of the stamping method by which the rotor and stator laminations of the motor of Fig. 1 are stamped.
Similar reference characters indicate similar parts throughout the several views of the drawings.
Description of the Pr~ferred Embodiment A motor 11 (Fig. 1) o~ the presen~ invention (shown as a ~witched reluctance motor although the present invention is not 80 limited) includes a ~our-pole stator 13 whose four teeth extend radially inwardly from the stator yoke to define a central bore in which a three-pole rotor 15 is suitably mounted for rotation. The axi~ of rotation of rotor 15 is defined by a tension rod 17, ac appears below. Phase windings 19 are wound ~round each tooth or pole of 8ta~0r 13 wi~h the polarltles shown to provlde the directions of mmf a5 indica~ed by the arrows l~belled 21. The teeth of stator 13 are equally spaced about its perimeter and the gaps between the teeth as measured at the c~ntral bore of the s~ator are just ~lightly larger than the w~d~h~ of the teeth themselves.
_ g _ ~2~86~)5 0963B ltl6/87 DN3499 E-1093 The teeth of rotor 15 are also e~ually ~paced around its perimeter. The width of the teeth o~ rotor 15 is generally the same as the width of the ~tator teeth at the central bore, so a to minimixe losses. The width of the ro~or teeth is also t sli~htly less than the gap between adjacent stator teeth for a reason which will become apparent in connection with the d~scus~on of Fig, 7. It should also be noted that the teeth of both rotor and ~tator are rounded a3 illustrated best in Fig. 1 to minimizes flux concentration and losses.
In motor 11, as best illu~trated in Fig. 2, the flux lines are as short as possible, while the mmf in stator yoke and poles always has the same direction. The mmf'~ between the phases always add since two of the opposing poles have an mmf towards the ro~or center while in the other two the mmf has a ~ir~ction from the rotor to the ~ator, as indicated by line~
21. This magn~tic circuit allows a ~ubstan~al reduction in core lo~e~.
The converter circuit for motor 11 is shown in Fig. 2A.
The converter takes filtered DC voltage of, for example, 315 volt~ and through the proper ~equential operation of a set o~
four power transistor switches or the like SWl through SW4, ~uppl~e~ power to the 8t~0r winding~ 19, here labelled l9A
through l9D. The converter includes a pair of capacitor~ Cl and C3 which perform a voltage dividing function. Each winding ha~
as~oc~ated ~herewith a flyback diode Dl through D4 connected between 1~ winding and one of th~ ~upply rails.
l)S
This converter arrangement has the advantage o being run by o~ly four switchln9 element~, which ~re controlled ln a conventional mann.er by a control c$rcuit (not ~hown) to energize the$r respective phase windings at the proper times~ ~ chopp~ng technique is used for limi~ing the curren~ values through the windings throughout the full speed range of the mo~or, which can operate up to and above 6000 RPM, Rotor 15 has no room for a conventional shaft if the flux density is to be held at acceptable levels in the rotor ~ore. And due t~ the odd number of rotor poles (three), the unbalanced radial forces exerted on the rotor are very large.
Thu~, an exceptionally ~tiff rotor construction is re~uired.
These requirements are achieved by ~aking a stack 25 (F~gs. 3 ~nd 4) o rotor laminations, stamped to their final outside diameter as described below in connection with Fig. 7, and pressing them together with a pair of identical end clamps 27 and 29. The end clamps are held together by a relatlvely thin, high guali~y ten4ion rod 31 through the ro~or center. ~ both en~s tension rod 31 is screwed into a larger diameter motor shaft 33 ~see Fig. ~). As shown in Fig. 4 at 3~A tension rod 31 may ~e hollow. Moreover, instead of being screwed into the rotor shaft 33, the tension rod may be bonded to ~he shaft by a suitable ~dhesive.
~ he end clamps are made rom non magnetic stainless steel, a~ ~hown in Fiy~. 5 and SA, or from cast aluminum, as ~hown in Fig~. 6 and 6~ (~he end ~lamp is labelled 27A in the latter two Figure~ ach of the embodiments of end clamp lncludes t~ree feet 35 and 35A respec~ively, disposable dlrectly above the teeth of ~he rotor laminations, for apply$ng pressure to the ~tack of l~minat~ons. The feet extend down below the bodies og the end clamps 80 that pres3ure exerted on the clamps i 3 transm~tted to the rotor laminat~on stack. The end clamps need only be elas~ic enou~h to as-Rure sufficient axial pressure on the rotor lamination~ under all rotor tempera~ures and condition~.
The ~equence of rotor assembly is best illustrated in connection with Fig. 3. The tenslon rod 31 (being threaded at both ends) iE; ~lrst ~crewed in motor shaft 33. A balancing disc 37, end clamp 29, stack 25 of rotor laminations, second end clamp 27, and a second balancing disc 39 are then stacked, one after the other, on the ten~ion rod. ~he assembly is then temporarily terminated by a nut 41, which represents at the same time the non-driving motor shaft end whish wlll later go into one of a pair of ~otor bearings 43 (F$g. 4) mounted in a pair of motor end shield~ ~5.
By using a holder 47 (Fig. 3), the assembly is lifted and the other end of tension rod 31 is ~crewed into a ~table 3upport 49. Following that, thc ro~or la~inatiuons are pressed down with three two-pronged tool~ 51 (only one of which i8 shown~
d~pla~d 120 degree ~rom each other. The upper prongs 53 of the tool~ exe ~ the maln pre~ure whlle the lower prongs 55 merely pushe~ ~he laminations ~o that they follow the movement of the upper end cïamp 27.
After the lamination~ have been sufficiently compressed, a tool 57 tightens nut 41, so that it move~ from its original position, shown in dot~ed lines in Fig . 3 to its f inal posi~ion, shown in solid lines. With this the process of compresslng the laminations is comple'ced and the assembly is unscrewed rom support 49 by using holder 47.
Before the rotor compression procedure, the two ends of motor shaft 33 are only drilled and threaded ~o receive tension rod 31. Their inal machining is done only after the compression cycle has been completed. This is done for ~wo reasons. During the compression, the shaft outer surfaces which mate with the sha~t bearings may get damaged. Secondly, it i8 not pogsible to hold the tolerance~ during the compression procedure to guarantee rotor shaft concentr~ity.
The final step in the rotor manufacture consists of zotor balancing. For that purpose, balancing disks 37 and 39 w~ th outside diameters somewhat smaller than the rotor outside diameter are used. The balancing Is achieved automa~-ic~lly by removing the nece3sary material from the balancing disc~.
Alternatively, if alum$num end caamps 27A of Flg~. 6 and 6A ~re used, the ini~ial rotor $mbalance would b~ lower than with the end clamps 27 of Fig3. 5 and sA~ In that case, the balancing discs can be omitted altogether from the rotor construction. The fine balancing in tha~ case i5 done by drilling holes such as hole 61 (Fig. 6A) through the aluminum end clamps as necessary.
~;~9~360~ -0963B 1/16/87 DN34sg E-1093 Of course, although ~he above construction has been de~cribed in connection wlth a switched reluctance motor, ~t should be appreciated that such a construc~ion is not ~o limited.
The ~ethod o stamping the rotor and tator laminations of motor 11 is illustrated in ~igs. 7 and 7A. As lndicated in Fig. 7, the ~tamping for the rotor lamination, labelled 15A and its central bore 19A are off-center with respect to the stamping ~or the stator lamination 13Ao As a result one of the teeth of rotor lamination 15A is taken from the gap between two of the teeth of the ~tator lamination. (This gap is enlarged in Fig. 7 over that of Fig. 1 for clarity of illustration.~ This arrangement, as opposed to the conventional stamping arrangement, allows the rotor and stator teeth to be stamped with rounded corner as best illustrated in Fig. 1.
~ he ~our stag~s, labelled a-d in Fig. 7A, of the stamping of both rotor and sta~or lamination~ from a single piece of metal start~ with ~he punching of rotor bore opening l9A in ~tage a. Note ~hat the rotor bore opening is off-center with respect to placement holes 71. Next the rotor lamination is stamped out along with a series o~ notche4 73, bes~ shown in Fig.
1. In the third stage, the interior configuration 75 of the ~tator l~mination 13A is s~amped out. And in the fourth stage the perimeter 77 of the stator lamination is stamped out, resulting in the finished stator lamination.
1~ -18~;05 0963~ 1/16/87 DN3499 E-1093 The methods and constructions described above provide several advantages. For one, they result in a suEficient cross-section in a three-pole rotor to reduce rotor core losses to an accepta~le level~ The three-pole rotor in turn reduces the stator losses by reducing the flux frequency in the ~tator yoke and poles, while still providing a substantial starting torque.
Secondly, ~he rotor lamination with the~e method are stamped to their final outside diameter, thus eliminating the rotor machining used wi~h conven~ional manufacturing. This in turn eliminates the short circuiting of rotor laminations -- another source of core losses. Thirdly, the rotor and stator poles are stamped with rounded poles, thus eliminating the flux concentration ln pole corners and reducing further the core losses. Finally, the rotor laminations are compres~ed so tightly that it is not neces ary to apply any anti-vibrating adhesives to the lamination~.
In view of the above, it will be seen that the various ob~ec~s and ~eatures of the present invention are achieved and other advantageous resul~ are obtained. As various changes ¢ould b~ made in the above con~truction~ ~nd methods without depar~ing ~rom the scope of the invention~ it is in~ended that all matter contained in the above des~ription and shown in the accompanying drawings shall be interpreted as illustrative and ~ot in a limiting sen~e,
Switched reluctance motors have attracted considerable attention over the past ten to ~ifteen years, primarily due to the simplicity of their construction and high power densities ~ratio between output power and weight), These motors are doubly ~alient motor~, having eeth on both the stator and the rotor, with phase windings only on the stator poles.
~xcept for very small (below 50 watt) motors, most switched reluctance motors are desiyned to operate below 2000 RPM
because the core losse~ in switched reluctance motors are several time~ l~rger than in conventional machines of ~he same size. ~or that r~ason, ~onven~ional wisdom is that switched reluctance motor~ ~re best suited for low speed applications. Of course ce~tain applications such as air cooling compressor motorY are required ~o operate at much higher speeds, such as 5000 RPM.
Early switched reluctance motors for larger power levels had six poles on the stator and four on tbe rotor. To reduce the number o~ power switches equired to supply power to these ~oto~, later design~ adopted an 8/4 construction (eight s~ator poles and four rotor poles), which required fewer power switches and.h~d improved starting torque.
" ~L29861r)5 0963B 1/16/87 DN349g E-1093 In order to limit the core losses ln prior machines, the direction of the stator magneto-motive ~orce (mmf~ was selected in ~u~h a way that the mmf direction ~n the rotor changed only once per full rotor revolution. In ~his way, the high frequency ~lux changes, which are proportional to the number of rotor poles, appeared only in the stator poles and the edges of the rotor poles. As a result, the core losses in the stator yoke and rotor core were reduced at the expense of some torque imbalance.
Of greater concern are the losses in the stator poles due to Elux bypass with such a construction. This bypass flux produces a torque in ~he opposite direction, and the bypass mmf has the opposite direction ~rom the main mmf to be e~tablished when the next phase is energi~ed. This change in the mmf direction in the stator poles of prior motors increased the ran~3e of flux variatlon and lead to increased core losses in stator poles.
In addition to the normal losse~ due to eddy currents and hysteresis, core losses are also affe~ted by the method conventionally used in stamping the rotor and stator lamin~tions. Stamping the laminations for conventional machines i done as follows: Fir ~ the stator ands rotor slots are stamped out ~nd then the rotor lamination i~ stamped from the stator lamination. ~s a result, bo~h stator and rotor teeth are sharply rectangular.
~IILZ~6l~5 Apparently the laminations or switched reluctance motors up to now have been made in the same way. As a result, the stator and rotor poles or teeth have sharp, rectangular corner~. Since switched reluctance motors have only one tooth per pole and s~nce they operate on the attraction between teeth/poles, there is a very strong flux concentration at the corners of each pole, pri~r to and after the alignment of the ~tator and rotor poles, resulting in increased losses. Rounding of these corners would, on the other hand, appear to regulre a new method o~ lamination stamping.
Furthermore, the stamping method presently used on conventional machines requires final machining of the rotor sur~ce, to obtain the exac~ rotor diameter. This machining normally results in short circulting of ~ome of the rotor lami~ations, as does the welding used to hold the laminations together. Although the frequency of the rotor flux in induction machines is low, this manufacturing method and the resulting short-circuiting of lamlnations cause~ additional losses which may amount to several percent of the total losses. In switched reluctance motors the machining necessary~to obtain the exact rvtor diameter would considerably increase ~he total losses given the frequen~y change o~ the r~t~r flux variations.
~ inally, large leakage flux when the rotor is in the po~itlon o~ maximum magnetic relu~tance results in ~lux line~
p~rpendicular to the rotor and stator surfaces. Rectangular poles make the flux lines longer, further increasing the losses.
~L~9860~; -For the above reasons, most of the ~witched reluctance motors used up to now have high quality laminations, with a thickness of 0.014~, which is smaller than in conventional machines. Furthermore, in order to reduce vibrations caused by the ~trong changes in mmf, present sw~tched reluctance motors have rotor lamination assemblie~ which are bonded together by adhesives.
Reducing the number of rotor poles i~ advantageous in designing switched reluctance motors for operation at higher ~peeds. However with conventional rotor construction, it i~ not Eeasible to reduce the number of rotor poles ~elow four. Even with four poles, the ~lux density (and thus the los es) is high due to the opening in the lamination stack for the motor shat, wh~ch decreases the effective cro~s-section of the rotor core.
For example, a three-pole rotor in a switched reluctance ~otor has no room for a conventional shaft if the ~lux density in the rotor core i8 to be held at ~n acceptable level. At the ~ame t~me, due to the odd number o rotor pole~, the radial force~
with a three-pole rotor are very large and unbalanced, reyuiring an even larger shaft than normal. These ~ery strong one-directional radial forces require an exceptionally ~tiff r~tor construction.
~Z9~605 Summary of the Inventlon Among the features of the present invention may be noted the provision of a motor with high speed, high horsepower and acceptable core losses.
The present invention also provides improved stator and rotor laminations with reduced losses.
A third object of the present invention is the provision of an improved rotor assembly and motor construction which eliminates the final machining and associated short circuiting of the rotor laminations.
A fourth object of the present invention is the provision of an improved rotor assembly and motor construction that eliminates the need to bond the rotor laminations.
A fifth object of the present invention is the provision of an improved rotor assembly construction which withstands large, unbalanced radial forces.
; Other objects and features will be in part apparent and in part point~d out hereinafter.
Briefly, an electric motor of the present invention has a stator with an axial bore therethrough, a rotor having an axis of rotation mounted for rotation about that axis of rotation in the bore of the stator, said rotor comprising a plurality of laminations disposed in a stack, the improvement comprising a tension rod extending axially through the rotor lamination stack and means disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position by compression, said laminations being unbonded with respect to each other, the compressing means including end clamps disposed at each end of the stack, the laminations having a plurality of teeth, the end clamps having a footprint corresponding to the shape of the laminations.
lZ~
The invention also involvss a rotor assembly for an electric motor having a stator with an axial bore therethrough, said rotor assembly having an axis of rotation and being mountable for rotation about said axis of rotation in the bore of the stator, comprising:
a plurality of laminations disposed in a stack;
a tension rod extending axially through the rotor lamination stack; and means disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position by compression, said laminations being unbonded with respect to each other;
the compressing means including end clamps disposed at each end of the stack, the laminations having a plurality of teeth, the end clamps having a footprint corresponding to the shape of the laminations.
Also, the invention concerns a method of constructing a rotor assembly comprising the steps of:
forming a plurality of rotor laminations each of which has a plurality of teeth;
orienting the plurality of rotor laminations to form a stack;
forming end clamps having footprints corresponding to the shape of the laminations;
fixedly securing an end clamp on each end of the stack to a tension rod extending through the stack to maintain compression of the stack; and machining the rotor laminations to their final dimensions after the tension rod is secured thereto.
36()5 Brief Description of ~he Drawlngs Fig. 1 is a ~chema~ic illustration of a motor made in accordance with the present invention;
Flg. 2 is a schematic illustration similar to Fig. 1, but on a reduced SGale, illustrating the direction o~ the mmf and the flow of flu~ in the motor of Fig. l;
Fig. 2A is an electrical schematic illustrating a converter circuit for the motor of Fig. l;
Fig. 3 is a simplified elevation illustrating the construction of the motor of Fig. l;
Fig. 4 i~ an elevation, with parts broken away for clarity, of the motor of Fig. l;
F19. 5 is a bottom plan of an end clamp used in the motor of Fig. l;
Fig. 5A is a side elevation, with parts broken away for clarity, of the end clamp of ~ig. 5;
Fig. 6 is a bot~om plan of a second embodiment of an end clamp used w~th the motor of Fig. l;
l~ S
0963B 1/16/87 DN34gg E-1093 Fig. 6~ is a cross-sectional view taken along line 6A --6A oiE Fig . 6;
Fig. 7 is a schematic illustration of the stamping patt~rn for ~he rotor and stator laminations of the motor of Fig.
s and Fig. 7A is a diagrammatic representation of the stamping method by which the rotor and stator laminations of the motor of Fig. 1 are stamped.
Similar reference characters indicate similar parts throughout the several views of the drawings.
Description of the Pr~ferred Embodiment A motor 11 (Fig. 1) o~ the presen~ invention (shown as a ~witched reluctance motor although the present invention is not 80 limited) includes a ~our-pole stator 13 whose four teeth extend radially inwardly from the stator yoke to define a central bore in which a three-pole rotor 15 is suitably mounted for rotation. The axi~ of rotation of rotor 15 is defined by a tension rod 17, ac appears below. Phase windings 19 are wound ~round each tooth or pole of 8ta~0r 13 wi~h the polarltles shown to provlde the directions of mmf a5 indica~ed by the arrows l~belled 21. The teeth of stator 13 are equally spaced about its perimeter and the gaps between the teeth as measured at the c~ntral bore of the s~ator are just ~lightly larger than the w~d~h~ of the teeth themselves.
_ g _ ~2~86~)5 0963B ltl6/87 DN3499 E-1093 The teeth of rotor 15 are also e~ually ~paced around its perimeter. The width of the teeth o~ rotor 15 is generally the same as the width of the ~tator teeth at the central bore, so a to minimixe losses. The width of the ro~or teeth is also t sli~htly less than the gap between adjacent stator teeth for a reason which will become apparent in connection with the d~scus~on of Fig, 7. It should also be noted that the teeth of both rotor and ~tator are rounded a3 illustrated best in Fig. 1 to minimizes flux concentration and losses.
In motor 11, as best illu~trated in Fig. 2, the flux lines are as short as possible, while the mmf in stator yoke and poles always has the same direction. The mmf'~ between the phases always add since two of the opposing poles have an mmf towards the ro~or center while in the other two the mmf has a ~ir~ction from the rotor to the ~ator, as indicated by line~
21. This magn~tic circuit allows a ~ubstan~al reduction in core lo~e~.
The converter circuit for motor 11 is shown in Fig. 2A.
The converter takes filtered DC voltage of, for example, 315 volt~ and through the proper ~equential operation of a set o~
four power transistor switches or the like SWl through SW4, ~uppl~e~ power to the 8t~0r winding~ 19, here labelled l9A
through l9D. The converter includes a pair of capacitor~ Cl and C3 which perform a voltage dividing function. Each winding ha~
as~oc~ated ~herewith a flyback diode Dl through D4 connected between 1~ winding and one of th~ ~upply rails.
l)S
This converter arrangement has the advantage o being run by o~ly four switchln9 element~, which ~re controlled ln a conventional mann.er by a control c$rcuit (not ~hown) to energize the$r respective phase windings at the proper times~ ~ chopp~ng technique is used for limi~ing the curren~ values through the windings throughout the full speed range of the mo~or, which can operate up to and above 6000 RPM, Rotor 15 has no room for a conventional shaft if the flux density is to be held at acceptable levels in the rotor ~ore. And due t~ the odd number of rotor poles (three), the unbalanced radial forces exerted on the rotor are very large.
Thu~, an exceptionally ~tiff rotor construction is re~uired.
These requirements are achieved by ~aking a stack 25 (F~gs. 3 ~nd 4) o rotor laminations, stamped to their final outside diameter as described below in connection with Fig. 7, and pressing them together with a pair of identical end clamps 27 and 29. The end clamps are held together by a relatlvely thin, high guali~y ten4ion rod 31 through the ro~or center. ~ both en~s tension rod 31 is screwed into a larger diameter motor shaft 33 ~see Fig. ~). As shown in Fig. 4 at 3~A tension rod 31 may ~e hollow. Moreover, instead of being screwed into the rotor shaft 33, the tension rod may be bonded to ~he shaft by a suitable ~dhesive.
~ he end clamps are made rom non magnetic stainless steel, a~ ~hown in Fiy~. 5 and SA, or from cast aluminum, as ~hown in Fig~. 6 and 6~ (~he end ~lamp is labelled 27A in the latter two Figure~ ach of the embodiments of end clamp lncludes t~ree feet 35 and 35A respec~ively, disposable dlrectly above the teeth of ~he rotor laminations, for apply$ng pressure to the ~tack of l~minat~ons. The feet extend down below the bodies og the end clamps 80 that pres3ure exerted on the clamps i 3 transm~tted to the rotor laminat~on stack. The end clamps need only be elas~ic enou~h to as-Rure sufficient axial pressure on the rotor lamination~ under all rotor tempera~ures and condition~.
The ~equence of rotor assembly is best illustrated in connection with Fig. 3. The tenslon rod 31 (being threaded at both ends) iE; ~lrst ~crewed in motor shaft 33. A balancing disc 37, end clamp 29, stack 25 of rotor laminations, second end clamp 27, and a second balancing disc 39 are then stacked, one after the other, on the ten~ion rod. ~he assembly is then temporarily terminated by a nut 41, which represents at the same time the non-driving motor shaft end whish wlll later go into one of a pair of ~otor bearings 43 (F$g. 4) mounted in a pair of motor end shield~ ~5.
By using a holder 47 (Fig. 3), the assembly is lifted and the other end of tension rod 31 is ~crewed into a ~table 3upport 49. Following that, thc ro~or la~inatiuons are pressed down with three two-pronged tool~ 51 (only one of which i8 shown~
d~pla~d 120 degree ~rom each other. The upper prongs 53 of the tool~ exe ~ the maln pre~ure whlle the lower prongs 55 merely pushe~ ~he laminations ~o that they follow the movement of the upper end cïamp 27.
After the lamination~ have been sufficiently compressed, a tool 57 tightens nut 41, so that it move~ from its original position, shown in dot~ed lines in Fig . 3 to its f inal posi~ion, shown in solid lines. With this the process of compresslng the laminations is comple'ced and the assembly is unscrewed rom support 49 by using holder 47.
Before the rotor compression procedure, the two ends of motor shaft 33 are only drilled and threaded ~o receive tension rod 31. Their inal machining is done only after the compression cycle has been completed. This is done for ~wo reasons. During the compression, the shaft outer surfaces which mate with the sha~t bearings may get damaged. Secondly, it i8 not pogsible to hold the tolerance~ during the compression procedure to guarantee rotor shaft concentr~ity.
The final step in the rotor manufacture consists of zotor balancing. For that purpose, balancing disks 37 and 39 w~ th outside diameters somewhat smaller than the rotor outside diameter are used. The balancing Is achieved automa~-ic~lly by removing the nece3sary material from the balancing disc~.
Alternatively, if alum$num end caamps 27A of Flg~. 6 and 6A ~re used, the ini~ial rotor $mbalance would b~ lower than with the end clamps 27 of Fig3. 5 and sA~ In that case, the balancing discs can be omitted altogether from the rotor construction. The fine balancing in tha~ case i5 done by drilling holes such as hole 61 (Fig. 6A) through the aluminum end clamps as necessary.
~;~9~360~ -0963B 1/16/87 DN34sg E-1093 Of course, although ~he above construction has been de~cribed in connection wlth a switched reluctance motor, ~t should be appreciated that such a construc~ion is not ~o limited.
The ~ethod o stamping the rotor and tator laminations of motor 11 is illustrated in ~igs. 7 and 7A. As lndicated in Fig. 7, the ~tamping for the rotor lamination, labelled 15A and its central bore 19A are off-center with respect to the stamping ~or the stator lamination 13Ao As a result one of the teeth of rotor lamination 15A is taken from the gap between two of the teeth of the ~tator lamination. (This gap is enlarged in Fig. 7 over that of Fig. 1 for clarity of illustration.~ This arrangement, as opposed to the conventional stamping arrangement, allows the rotor and stator teeth to be stamped with rounded corner as best illustrated in Fig. 1.
~ he ~our stag~s, labelled a-d in Fig. 7A, of the stamping of both rotor and sta~or lamination~ from a single piece of metal start~ with ~he punching of rotor bore opening l9A in ~tage a. Note ~hat the rotor bore opening is off-center with respect to placement holes 71. Next the rotor lamination is stamped out along with a series o~ notche4 73, bes~ shown in Fig.
1. In the third stage, the interior configuration 75 of the ~tator l~mination 13A is s~amped out. And in the fourth stage the perimeter 77 of the stator lamination is stamped out, resulting in the finished stator lamination.
1~ -18~;05 0963~ 1/16/87 DN3499 E-1093 The methods and constructions described above provide several advantages. For one, they result in a suEficient cross-section in a three-pole rotor to reduce rotor core losses to an accepta~le level~ The three-pole rotor in turn reduces the stator losses by reducing the flux frequency in the ~tator yoke and poles, while still providing a substantial starting torque.
Secondly, ~he rotor lamination with the~e method are stamped to their final outside diameter, thus eliminating the rotor machining used wi~h conven~ional manufacturing. This in turn eliminates the short circuiting of rotor laminations -- another source of core losses. Thirdly, the rotor and stator poles are stamped with rounded poles, thus eliminating the flux concentration ln pole corners and reducing further the core losses. Finally, the rotor laminations are compres~ed so tightly that it is not neces ary to apply any anti-vibrating adhesives to the lamination~.
In view of the above, it will be seen that the various ob~ec~s and ~eatures of the present invention are achieved and other advantageous resul~ are obtained. As various changes ¢ould b~ made in the above con~truction~ ~nd methods without depar~ing ~rom the scope of the invention~ it is in~ended that all matter contained in the above des~ription and shown in the accompanying drawings shall be interpreted as illustrative and ~ot in a limiting sen~e,
Claims (16)
1. In an electric motor having a stator with an axial bore therethrough, a rotor having an axis of rotation mounted for rotation about that axis of rotation in the bore of the stator, said rotor comprising a plurality of laminations disposed in a stack, the improvement comprising a tension rod extending axially through the rotor lamination stack and means disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position by compression, said laminations being unbonded with respect to each other, the compressing means including end clamps disposed at each end of the stack, the laminations having a plurality of teeth, the end clamps having a footprint corresponding to the shape of the laminations.
2. The motor as set forth in claim 1 wherein the rotor has an odd number of poles, the compression of the rotor stack being sufficient to oppose the resulting radial forces exerted on the stack without failure of the rotor.
3. The motor as set forth in claim 2 wherein the rotor has three poles.
4. The motor as set forth in claim 1 wherein the tension rod is hollow.
5. The motor as set forth in claim 1 wherein the stator and the rotor both have teeth, and wherein the teeth of both rotor and stator have rounded corners.
6. The motor as set forth in claim 1 further including means independent of the rotor stack for balancing the rotor after assembly of the stack, said balancing means comprising a pair of disc-shaped non-magnetic balancing members disposed at opposite ends of the stack with the centers of the disc-shaped non-magnetic balancing members disposed along the axis of rotation of the rotor, said disc-shaped non-magnetic balancing members each being unitary and each being composed of material which is removable from said member to effect balancing of the rotor.
7. A rotor assembly for an electric motor having a stator with an axial bore therethrough, said rotor assembly having an axis of rotation and being mountable for rotation about said axis of rotation in the bore of the stator, comprising:
a plurality of laminations disposed in a stack;
a tension rod extending axially through the rotor lamination stack; and means disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position by compression, said laminations being unbonded with respect to each other;
the compressing means including end clamps disposed at each end of the stack, the laminations having a plurality of teeth, the end clamps having a footprint corresponding to the shape of the laminations.
a plurality of laminations disposed in a stack;
a tension rod extending axially through the rotor lamination stack; and means disposed at each end of the rotor lamination stack and secured to the tension rod for compressing the stack to hold the laminations of the stack fixedly in position by compression, said laminations being unbonded with respect to each other;
the compressing means including end clamps disposed at each end of the stack, the laminations having a plurality of teeth, the end clamps having a footprint corresponding to the shape of the laminations.
8. The rotor assembly as set forth in claim 7 wherein the rotor assembly has an odd number of poles, the compression of the rotor stack being sufficient to oppose the resulting radial forces exerted during operation on the stack without failure of the rotor.
9. The rotor assembly as set forth in claim 8 wherein the assembly has three poles.
10. The rotor assembly as set forth in claim 7 wherein the tension rod is hollow.
11. The rotor assembly as set forth in claim 10 wherein the laminations have teeth with rounded corners.
12. The rotor assembly as set forth in claim 7 further including means independent of the stack for balancing the assembly after assembly of the stack, said balancing means including a pair of disc-shaped non-magnetic balancing members disposed at opposite ends of the stack, with the centers of the disc-shaped non-magnetic balancing members disposed along the axis of rotation of the rotor, said disc-shaped non-magnetic balancing members each being unitary and each being composed of material which is removable from said member to effect balancing of the rotor.
13. A method of constructing a rotor assembly comprising the steps of:
forming a plurality of rotor laminations each of which has a plurality of teeth;
orienting the plurality of rotor laminations to form a stack forming end clamps having footprints corresponding to the shape of the laminations;
fixedly securing an end clamp on each end of the stack to a tension rod extending through the stack to maintain compression of the stack; and machining the rotor laminations to their final dimensions after the tension rod is secured thereto.
forming a plurality of rotor laminations each of which has a plurality of teeth;
orienting the plurality of rotor laminations to form a stack forming end clamps having footprints corresponding to the shape of the laminations;
fixedly securing an end clamp on each end of the stack to a tension rod extending through the stack to maintain compression of the stack; and machining the rotor laminations to their final dimensions after the tension rod is secured thereto.
14. The method as set forth in claim 13 including the further step of securing each end of the tension rod to a rotor shaft segment, said tension rod and the rotor shaft segments being co-axial so as to define the axis of rotation of the rotor assembly.
15. The method as set forth in claim 13 including the step of providing balancing members at each end of the stack, further including the step of balancing the rotor assembly by removing material from the balancing members after the steps of claim 13 are completed.
16. In an electric motor having a stator with an axial bore therethrough, a rotor mounted for rotation in the bore of the stator, said rotor comprising a plurality of laminations disposed in a stack, the improvement comprising means for compressing the stack to hold the laminations in the stack fixedly in position substantially by compression; and two rotor shaft segments, disposed axially on opposite sides of the lamination stack, said compressing means including a hollow tension rod secured to the rotor shaft segments to define the axis of rotation of the rotor, the transverse cross sectional area of the tension rod being substantially less than the transverse cross-sectional area of the rotor shaft segments, and end clamps disposed at each end of the stack and secured to the tension rod, the laminations having a plurality of teeth, and the end clamps having a footprint corresponding to the shape of the laminations.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/007,608 US5128576A (en) | 1987-01-28 | 1987-01-28 | Rotor assembly and motor construction and method of making same |
| US007,608 | 1993-01-22 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616214A Division CA1320529C (en) | 1987-01-28 | 1991-11-01 | Rotor assembly and motor construction and method of making same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1298605C true CA1298605C (en) | 1992-04-07 |
Family
ID=21727167
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000550129A Expired - Lifetime CA1298605C (en) | 1987-01-28 | 1987-10-23 | Rotor assembly and motor construction and method of making same |
| CA000616214A Expired - Fee Related CA1320529C (en) | 1987-01-28 | 1991-11-01 | Rotor assembly and motor construction and method of making same |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616214A Expired - Fee Related CA1320529C (en) | 1987-01-28 | 1991-11-01 | Rotor assembly and motor construction and method of making same |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5128576A (en) |
| EP (1) | EP0278200B1 (en) |
| JP (1) | JPS63194547A (en) |
| CA (2) | CA1298605C (en) |
| DE (1) | DE3786911T2 (en) |
| DK (1) | DK34588A (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02123936A (en) * | 1988-10-31 | 1990-05-11 | Brother Ind Ltd | Rotor of reluctance motor |
| DE4106131C2 (en) * | 1991-02-27 | 1994-07-28 | Licentia Gmbh | Runner for small electric motors |
| US5432390A (en) * | 1992-05-15 | 1995-07-11 | Emerson Electric Co. | Switched reluctance motor |
| US5386163A (en) * | 1993-01-07 | 1995-01-31 | Emerson Electric Co. | Counterweighted rotor |
| EP0748027B1 (en) | 1995-06-07 | 2006-09-06 | General Electric Company | Dynamoelectric machine and rotor construction thereof |
| DE19743549C2 (en) * | 1997-10-01 | 1999-12-30 | Siemens Ag | Method of manufacturing a laminated electrical machine |
| US6123167A (en) * | 1998-06-11 | 2000-09-26 | Trw Inc. | Electric steering motor with one-piece metal shell |
| US6193473B1 (en) * | 1999-03-31 | 2001-02-27 | Cooper Turbocompressor, Inc. | Direct drive compressor assembly with switched reluctance motor drive |
| US6616421B2 (en) | 2000-12-15 | 2003-09-09 | Cooper Cameron Corporation | Direct drive compressor assembly |
| US6817845B2 (en) * | 2002-04-19 | 2004-11-16 | Envirotech Pumpsystems, Inc. | Centrifugal pump with switched reluctance motor drive |
| JP4107154B2 (en) * | 2003-01-16 | 2008-06-25 | 株式会社デンソー | Rotating equipment with torque limiter function |
| US7451543B2 (en) * | 2004-10-04 | 2008-11-18 | Emerson Electric Co. | Methods of securing a bearing with an adaptor sleeve within an opening of a housing |
| US20060072288A1 (en) * | 2004-10-04 | 2006-04-06 | Stewart William P | Electric machine with power and control electronics integrated into the primary machine housing |
| US7408282B2 (en) * | 2004-10-04 | 2008-08-05 | Emerson Electric Co. | End shields and stators and related methods of assembly |
| GB2468310B (en) * | 2009-03-03 | 2015-01-07 | Dyson Technology Ltd | Stator core |
| IT1404118B1 (en) * | 2011-02-10 | 2013-11-15 | Magneti Marelli Spa | METHOD OF CONSTRUCTION OF A MAGNETIC CORE CONSTITUTED BY SHEARS PACKED FOR AN ELECTRIC MACHINE |
Family Cites Families (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US501194A (en) * | 1893-07-11 | Revolving armature for electric machines | ||
| CA348975A (en) * | 1935-03-19 | William Walton George | Synchronous electric motor | |
| US538344A (en) * | 1895-04-30 | Harry penn and loft us lowndes | ||
| US1444495A (en) * | 1921-10-28 | 1923-02-06 | Carmen Z Coleman | Electric motor |
| FR643244A (en) * | 1926-11-01 | 1928-09-12 | Esslingen Maschf | Method of manufacturing short-circuited rotors. for electrical machines |
| US2232773A (en) * | 1938-12-29 | 1941-02-25 | Hoover Co | Armature construction |
| US2558737A (en) * | 1946-12-13 | 1951-07-03 | Master Electric Co | Rotor balancing means |
| DE1042736B (en) * | 1957-11-11 | 1958-11-06 | Licentia Gmbh | Fixing of the laminated core of electrical machines on a shaft by means of a tolerance ring |
| FR1275834A (en) * | 1960-12-09 | 1961-11-10 | Fiat Spa | Improvements to alternating current generators, in particular for electrical installations of motor vehicles |
| DE1162465B (en) * | 1961-06-15 | 1964-02-06 | Licentia Gmbh | Runner plate for electrical machines clamped to form a self-supporting component |
| CH518642A (en) * | 1969-10-31 | 1972-01-31 | Tsnii T I Mash | Method for manufacturing the rotor of a turbo generator |
| US3650022A (en) * | 1969-12-12 | 1972-03-21 | Singer Co | Method of assembling the rotor pad shaft of a dynamoelectric machine |
| US3671789A (en) * | 1971-01-19 | 1972-06-20 | Canadian Patents Dev | Synchronous reluctance motors having rotor segments of extended pole span |
| US3877629A (en) * | 1972-10-16 | 1975-04-15 | Textron Inc | High speed rotor for friction welding systems |
| JPS5049607A (en) * | 1973-09-04 | 1975-05-02 | ||
| US3965385A (en) * | 1974-01-28 | 1976-06-22 | Raytheon Company | Semiconductor heterojunction television imaging tube |
| GB2082847B (en) * | 1980-08-18 | 1984-07-25 | Chloride Group Ltd | Variable reluctance motor |
| JPS5866557A (en) * | 1981-10-16 | 1983-04-20 | Hitachi Ltd | Manufacture of motor core |
| US4619028A (en) * | 1983-03-25 | 1986-10-28 | L H Carbide Corporation | Apparatus for manufacture of laminated parts |
| DE3327744A1 (en) * | 1983-08-01 | 1985-02-21 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR BALANCING WINDED RUNNERS OF ELECTRICAL MACHINES |
| US4501985A (en) * | 1984-05-01 | 1985-02-26 | Westinghouse Electric Corp. | Dynamoelectric machine with end turn support assembly having fasteners with locking devices |
| US4977344A (en) * | 1987-01-28 | 1990-12-11 | Emerson Electric Co. | Rotor assembly and motor construction |
-
1987
- 1987-01-28 US US07/007,608 patent/US5128576A/en not_active Expired - Fee Related
- 1987-10-23 CA CA000550129A patent/CA1298605C/en not_active Expired - Lifetime
- 1987-12-17 DE DE87630270T patent/DE3786911T2/en not_active Expired - Fee Related
- 1987-12-17 EP EP87630270A patent/EP0278200B1/en not_active Expired - Lifetime
- 1987-12-24 JP JP62329420A patent/JPS63194547A/en active Pending
-
1988
- 1988-01-26 DK DK034588A patent/DK34588A/en not_active Application Discontinuation
-
1991
- 1991-11-01 CA CA000616214A patent/CA1320529C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DK34588A (en) | 1988-07-29 |
| EP0278200A1 (en) | 1988-08-17 |
| US5128576A (en) | 1992-07-07 |
| DE3786911D1 (en) | 1993-09-09 |
| JPS63194547A (en) | 1988-08-11 |
| DK34588D0 (en) | 1988-01-26 |
| CA1320529C (en) | 1993-07-20 |
| EP0278200B1 (en) | 1993-08-04 |
| DE3786911T2 (en) | 1993-11-11 |
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