WO2020128147A1 - A coil for a winding of an electric machine - Google Patents

A coil for a winding of an electric machine Download PDF

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Publication number
WO2020128147A1
WO2020128147A1 PCT/FI2019/050826 FI2019050826W WO2020128147A1 WO 2020128147 A1 WO2020128147 A1 WO 2020128147A1 FI 2019050826 W FI2019050826 W FI 2019050826W WO 2020128147 A1 WO2020128147 A1 WO 2020128147A1
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WO
WIPO (PCT)
Prior art keywords
coil
portions
conductor
sides
coil portions
Prior art date
Application number
PCT/FI2019/050826
Other languages
French (fr)
Inventor
Timo NYKÄNEN
Jouni RYHÄNEN
Petri PESONEN
Original Assignee
Lappeenrannan-Lahden Teknillinen Yliopisto Lut
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Lappeenrannan-Lahden Teknillinen Yliopisto Lut filed Critical Lappeenrannan-Lahden Teknillinen Yliopisto Lut
Publication of WO2020128147A1 publication Critical patent/WO2020128147A1/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
    • H02K3/18—Windings for salient poles
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
    • H02K3/28—Layout of windings or of connections between windings
    • 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
    • H02K15/04—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of windings, prior to mounting into machines
    • H02K15/0435—Wound windings
    • H02K15/0442—Loop windings
    • H02K15/045—Form wound coils
    • 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
    • H02K15/08—Forming windings by laying conductors into or around core parts
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
    • H02K3/12—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors arranged in slots
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
    • H02K3/24—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors with channels or ducts for cooling medium between the conductors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/46—Fastening of windings on the stator or rotor structure
    • H02K3/52—Fastening salient pole windings or connections thereto

Definitions

  • the disclosure relates generally to electric machines. More particularly, the disclosure relates to a coil that can act as an element of a winding of an electric machine. Furthermore, the disclosure relates to a method for manufacturing a coil of a winding of an electric machine. Furthermore, the disclosure relates to a tool for shaping a coil. Furthermore, the disclosure relates to a machine element of an electric machine.
  • the machine element can be for example a part of a stator or a part of a rotor of an electric machine.
  • a magnetic flux is developed between the electromagnetically active parts of the electric machine.
  • at least one of the above-mentioned electromagnetically active parts comprises a ferromagnetic core element and one or more windings installed in slots of the core element.
  • the core element can be for example a stator core of a rotating electric machine and the windings can be stator windings of the rotating electric machine.
  • the rotating electric machine can be for example an electrically excited synchronous machine, a permanent magnet machine, an induction machine, or a reluctance machine.
  • the windings are constituted by conductors each comprising a core portion and a layer of electrically insulating material surrounding the core portion.
  • the core portion comprises electrically conductive material, e.g. copper, for conducting electric current.
  • the conductors are either round wire conductors or shaped conductors that typically have a rectangular cross-sectional profile.
  • the core portion of a shaped conductor can be for example a single conductor bar, e.g. a copper bar.
  • the core portion of a shaped conductor may comprise many conductor bars which have rectangular cross-sectional profiles and are positioned with respect to each other so that a desired cross-sectional profile of the shaped conductor is achieved.
  • the conductor bars can be electrically insulated from each other. It is also possible that the core portion of a shaped conductor comprises a bundle of filamentary conductors.
  • Shaped conductors have certain advantages with respect to round wire conductors.
  • One of the advantages is that inductances of different phases of a multiphase, e.g. a three phase, winding can be made more symmetric when using shaped conductors than when using round wire conductors because shaped conductors are located in a more deterministic way in slots and end-winding regions than round wire conductors do.
  • Another advantage of shaped conductors is that the conductor space factor, i.e. the filling factor, of slots can be in some cases higher than in cases where round wire conductors are used.
  • a third advantage of shaped conductors is that, in many cases, a shaped conductor can be arranged to comprise a tubular channel for conducting water or some other suitable liquid or gaseous cooling fluid.
  • Shaped conductors are, however, not free from challenges.
  • One of the challenges is related to coil-ends where a conductor is adapted to implement an elevation between adjacent coil-turns.
  • Figures 1a and 1 b illustrate a traditional coil 100 that comprises a coil-end 114 where a conductor of the coil is adapted to implement the elevation h between adjacent coil turns. In this exemplifying case, the conductor has a rectangular cross-section.
  • Figure 1 c shows a conductor portion 120 separately. The viewing directions related to figures 1 a-1 c are indicated with a coordinate system 199.
  • the conductor has S-type curvature in the coil- end 114 so that the coil-end 114 has successive and oppositely directed curvatures R- ja R+.
  • the S-type curvature can be however challenging to implement so that its shape is accurately enough a shape needed for implementing the elevation between the adjacent coil-turns and for maintaining straight and parallel coil-sides which represent an active part of the coil 100. Summary
  • the word“geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object.
  • the geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional.
  • An elongated object e.g. an elongated conductor, is considered parallel with a two-dimensional geometric plane when the geometric tangent of the elongated object is at each point of the elongated object perpendicular to the geometric normal of the geometric plane.
  • a coil according to the invention comprises a conductor having a core portion and a layer of electrically insulating material surrounding the core portion.
  • the core portion comprises electrically conductive material such as e.g. copper or aluminum for conducting electric current.
  • the above-mentioned conductor is arranged to form coil portions having a same geometric magnetic axis and nested so that a first one of the coil portions is arranged to surround a second one of the coil portions.
  • Each of the coil portions comprises:
  • each of the second conductor portions constituting a first coil-end between first ends of the first and second coil-sides, each of the second conductor portions being parallel with a first geometric plane perpendicular to the geometric magnetic axis, and the second conductor portions being one upon another in a direction of the geometric magnetic axis, and
  • the conductor further comprises one or more connecting portions that are parallel with the first geometric plane and connect the coil portions in series so that the helical paths related to adjacent ones of the coil portions have opposite handedness.
  • the above-mentioned third conductor portions of each coil portion are crossed with respect to the corresponding third conductor portions of an adjacent coil portion so that the third conductor portions implement an elevation between successive conductor turns of the coil portions. Therefore, there is no need for S-type curvatures in the conductor.
  • the third conductor portions of adjacent coil portions are crossed with respect to each other because the helical paths related to the adjacent coil portions have opposite handedness.
  • a coil according to an exemplifying and non-limiting embodiment of the invention comprises three or more nested coil portions of the kind described above.
  • a machine element for an electric machine can be for example a part of a stator or a part of a rotor of an electric machine.
  • a machine element according to the invention comprises:
  • a core element comprising a yoke section and teeth connected to the yoke section, slots being formed between adjacent ones of the teeth
  • each coil being arranged to surround one of the teeth of the core element and a coil-width of each coil being equal to the slot-pitch of the core element.
  • a new method for manufacturing a coil according to the invention is provided.
  • the method comprises: shaping a conductor to form i) coil portions having a same geometric magnetic axis and nested so that a first one of the coil portions surrounds a second one of the coil portions and to form ii) one or more connecting portions connecting the coil portions in series, each of the coil portions comprising first conductor portions constituting first and second coil-sides, second conductor portions constituting a first coil-end between first ends of the first and second coil-sides, and third conductor portions constituting a second coil-end between second ends of the first and second coil-sides so that the coil portion follows a helical path, the connecting portions connecting the coil portions in series so that the helical paths related to the first and second ones of the coil portions have opposite handedness, pressing the first coil-ends of the coil portions between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil so that the second conductor portions of each of the coil portions are one upon another in a direction of the geometric magnetic axis, and bending the first coil-side of the first
  • a first pressing member for pressing the first coil-ends of the coil portions between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil
  • a second pressing member comprising projections for bending the first coil- side of the first one of the coil portions and the second coil-side of the second one of the coil portions in a first direction parallel with the geometric magnetic axis without bending the second coil-side of the first one of the coil portions and the first coil-side of the second one of the coil portions in the first direction.
  • figures 1 a, 1 b, and 1 c illustrate a coil according to the prior art for a winding of an electric machine
  • figures 2a, 2b, and 2c illustrate a coil according to an exemplifying and non-limiting embodiment for a winding of an electric machine
  • figures 3a, 3b, and 3c illustrate a coil according to another exemplifying and non limiting embodiment for a winding of an electric machine
  • figure 4a shows a flowchart of a method according to an exemplifying and non limiting embodiment for manufacturing a coil of a winding of an electric machine
  • figures 4b, 4c, 4d, 4e, 4f, and 4g illustrate an exemplifying coil after method stages presented in figure 4a
  • figures 4c-4f illustrate also a tool according to an exemplifying and non-limiting embodiment for shaping
  • the core portion can be a single conductor bar, e.g. a copper bar.
  • the core portion may comprise many conductor bars which have rectangular cross-sectional profiles and are positioned with respect to each other so that a desired cross-sectional profile of the conductor is achieved.
  • the conductor bars can be electrically insulated from each other.
  • Each of the coil portions 202 and 203 comprises third conductor portions 213 that constitute a second coil-end between second ends of the first and second coil-sides of the coil portion under consideration so that the coil portion is arranged to follow a helical path.
  • the second coil-end of the coil portion 202 is denoted with a reference 214 and the second coil-end of the coil portion 203 is denoted with a reference 215.
  • Figure 2c shows the above-mentioned third conductor portions 213 so that the third conductor portions of the coil portion 203 are depicted with solid lines and the third conductor portions of the coil portion 202 are depicted with dashed lines.
  • the coil-sides 206-209 are straight and the first coil-sides 206 and 208 of the coil portions 202 and 203 are parallel with the second coil-sides 207 and 209 of the coil portions.
  • the above- described principle for implementing an elevation between successive turns of a coil is, however, applicable also on cases where coil-sides are curved and/or first and second coil-sides are non-parallel with each other.
  • an axial-flux electric machine may comprise coils where coil-sides are curved and/or first and second coil-sides are non-parallel with each other.
  • the core portion of the conductor 201 comprises a tubular channel for conducting cooling fluid in a longitudinal direction of the conductor 201 .
  • the tubular channel is denoted with a reference 216.
  • the core portion of the conductor 201 comprises a tube constituting the tubular channel.
  • the tube can be made of material different from the electrically conductive material of the core portion of the conductor 201 .
  • the tube can be made of e.g. steel. It is also possible that the core portion of the conductor 201 is a hollow bar of electrically conductive material, e.g. copper, and there is no separate tube inside the conductor.
  • Figure 3a shows a top view of a coil 300 according to an exemplifying and non limiting embodiment.
  • Figure 3b shows a view of a section taken along a line A-A shown in figure 3a so that the section plane is parallel with the yz-plane of a coordinate system 399.
  • Figure 3c shows a view of a section taken along a line B-B shown in figure 3a so that the section plane is parallel with the yz-plane of the coordinate system 399.
  • the viewing directions related to figures 3b and 3c are indicated by the coordinate system 399.
  • the coil 300 comprises a conductor 301 comprising a core portion and a layer of electrically insulating material surrounding the core portion.
  • the conductor 301 is arranged to form coil portions 302, 302, and 304 that have a same geometric magnetic axis 317 and are nested so that a first one 302 of the coil portions is arranged to surround a second one 303 of the coil portions and the second one 303 of the coil portions is arranged to surround a third one 304 of the coil portions.
  • the geometric magnetic axis 317 is parallel with the z-axis of the coordinate system 399.
  • Each of the coil portions 302-304 comprises first conductor portions 305 constituting first and second coil-sides of the coil portion under consideration.
  • Each of the coil portions 302-304 comprises second conductor portions 310 that constitute a first coil-end between first ends of the first and second coil-sides of the coil portion under consideration.
  • Figure 3c shows the above-mentioned third conductor portions 313 so that the third conductor portions of the coil portion 304 are depicted with solid lines, the third conductor portions of the coil portion 303 are depicted with dashed lines, and the third conductor portions of the coil portion 302 are depicted with dash-and-dot lines.
  • the conductor 301 further comprises connecting portions that connects the above- mentioned coil portions 302-304 in series so that the helical paths related adjacent ones of the coil portions have opposite handedness.
  • the connecting portions are denoted with references 318 and 319.
  • the connecting portion 319 is shown also in figure 3a.
  • the connecting portions 318 and 319 are parallel with the xy-plane of the coordinate system 399 and the above- mentioned third conductor portions of adjacent coil portions, such as coil portions 304 and 303, are crossed with respect to each other.
  • the third conductor portions of adjacent coil portions are crossed with respect to each other because the helical paths related to the adjacent coil portions have opposite handedness.
  • the coil after the manufacturing phase 401 is shown in figure 4b.
  • first and second coil portions each of which comprises first conductor portions constituting first and second coil-sides, second conductor portions constituting a first coil-end between first ends of the first and second coil-sides, and third conductor portions constituting a second coil-end between second ends of the first and second coil-sides so that the coil portion follows a helical path.
  • the above- mentioned connecting portions connect the first and second coil portions in series so that the helical paths related to the first and second coil portions have opposite handedness.
  • the above-mentioned action 403 is illustrated in figure 4c that shows a section taken along a line A-A shown in figures 4b and 4g so that the section plane is parallel with the yz-plane of a coordinate system 499.
  • the tool for shaping the coil comprises a first pressing member 421 for pressing the first coil-ends 41 1 and 412 between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil.
  • One of the planar pressing surfaces is a surface of the first pressing member 421 and the other of the planar pressing surfaces is a surface of an element 422.
  • the above-mentioned action 404 is illustrated in figures 4d-4f each of which shows a section taken along a line B-B shown in figures 4b and 4g so that the section plane is parallel with the yz-plane of the coordinate system 499.
  • the tool for shaping the coil comprises a second pressing member 427 that comprises projections 428 and 429.
  • the second pressing member 427 is suitable for bending the first coil-side 406 of the coil portion 402 and the second coil-side 409 of coil portion 403 in a first direction parallel with the geometric magnetic axis without bending the second coil-side 407 of the coil portion 402 and the first coil-side 408 of the coil portion 403 in the first direction so as to align the second ends of the first and second coil-sides of the coil portions with respect to each other in the first direction.
  • the first direction is the negative z-direction of the coordinate system 499.
  • the tool for shaping the coil comprises means for producing forces for pressing the first and second pressing members 421 and 427 in the way described above with reference to figures 4c-4g.
  • the means for producing the forces are not shown in figures 4c-4g, but the means can be for example mechanical, hydraulic, or electromechanical.
  • the first coil- side 406 of the coil portion 402 and the second coil-side 409 of the coil portion 403 are bend so that the second end of the first coil-side 406 of the coil portion 402 and the second end of the second coil-side 409 of the coil portion 403 pass a position where the second ends of the first and second coil-sides of the coil portions are aligned with respect to each other in the above-mentioned first direction so as to compensate for a spring-back effect occurring in the coil after the bending action.
  • figure 4e shows that the second pressing member 427 of the tool is suitable for bending the first coil-side 406 of the coil portion 402 and the second coil-side 409 of the coil portion 403 so that the second end of the first coil-side 406 of the coil portion 402 and the second end of the second coil-side 409 of the coil portion 403 pass the position where the second ends of the first and second coil-sides of the coil portions are aligned with respect to each other.
  • Figure 4f illustrates a situation where the second pressing member 427 has been removed after the bending action illustrated in figure 4e.
  • the connection end 430 can be bent as shown in figure 4f.
  • the connection end 431 has not been bent in the same way because, as shown in figure 4g, the connection end 431 crosses the second coil-end 414 of the first coil portion 402.
  • the exemplifying tool illustrated in figures 4c-4g comprises a support member 425 for protruding through a loop constituted by the coil. Furthermore, this exemplifying tool comprises support walls 423 and 424 for supporting the first and second coil- sides of the coil portions so that the coil is between the support walls and the geometric magnetic axis of the coil is parallel with the support walls.
  • a sliding membrane is installed in a gap between the second coil-ends 414 and 415 of the coil portions 402 and 403 prior to the bending action illustrated in figure 4e.
  • the gap is denoted with a reference 450.
  • the sliding membrane facilitates the movement of the second coil-ends 414 and 415 with respect to each other during the above-mentioned bending action. It is also possible to install a sliding membrane in a gap between the coil-sides of the coil portions and/or in a gap between the first coil-ends 41 1 and 412 of the coil portions.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Windings For Motors And Generators (AREA)
  • Manufacture Of Motors, Generators (AREA)

Abstract

of the disclosure:A coil (200) for a winding of an electric machine comprises a conductor (201) constituting nested coil portions (202, 203) having a same geometric magnetic axis. Each coil portion comprises coil-sides (206-209), a first coil-end (211, 212), and a second coil-end (214, 215). Portions of the conductor constituting the first coil-end of each coil portion are parallel with a geometric plane perpendicular to a magnetic axis (217) of the coil and one upon another in a direction of the magnetic axis, whereas portions of the conductor constituting the second coil-end are arranged to implement an elevation between successive conductor turns of the coil portion so that the coil portion follows a helical path. The coil portions are connected in series so that the helical paths related to adjacent ones of the coil portions have opposite handedness.

Description

A coil for a winding of an electric machine
Technical field
The disclosure relates generally to electric machines. More particularly, the disclosure relates to a coil that can act as an element of a winding of an electric machine. Furthermore, the disclosure relates to a method for manufacturing a coil of a winding of an electric machine. Furthermore, the disclosure relates to a tool for shaping a coil. Furthermore, the disclosure relates to a machine element of an electric machine. The machine element can be for example a part of a stator or a part of a rotor of an electric machine.
Background
In an electric machine, such as an electric motor or a generator, a magnetic flux is developed between the electromagnetically active parts of the electric machine. Typically, at least one of the above-mentioned electromagnetically active parts comprises a ferromagnetic core element and one or more windings installed in slots of the core element. The core element can be for example a stator core of a rotating electric machine and the windings can be stator windings of the rotating electric machine. The rotating electric machine can be for example an electrically excited synchronous machine, a permanent magnet machine, an induction machine, or a reluctance machine. The windings are constituted by conductors each comprising a core portion and a layer of electrically insulating material surrounding the core portion. The core portion comprises electrically conductive material, e.g. copper, for conducting electric current. The conductors are either round wire conductors or shaped conductors that typically have a rectangular cross-sectional profile. The core portion of a shaped conductor can be for example a single conductor bar, e.g. a copper bar. For another example, the core portion of a shaped conductor may comprise many conductor bars which have rectangular cross-sectional profiles and are positioned with respect to each other so that a desired cross-sectional profile of the shaped conductor is achieved. The conductor bars can be electrically insulated from each other. It is also possible that the core portion of a shaped conductor comprises a bundle of filamentary conductors. In this case, the cross-sectional profile of the conductor is determined by the layer of the electrically insulating material surrounding the core portion and/or by resin or other filler material among the filamentary conductors. The bundle of the filamentary conductors may comprise for example one or more Litz-wires where the filamentary conductors are individually insulated and twisted and/or woven together.
Shaped conductors have certain advantages with respect to round wire conductors. One of the advantages is that inductances of different phases of a multiphase, e.g. a three phase, winding can be made more symmetric when using shaped conductors than when using round wire conductors because shaped conductors are located in a more deterministic way in slots and end-winding regions than round wire conductors do. Another advantage of shaped conductors is that the conductor space factor, i.e. the filling factor, of slots can be in some cases higher than in cases where round wire conductors are used. A third advantage of shaped conductors is that, in many cases, a shaped conductor can be arranged to comprise a tubular channel for conducting water or some other suitable liquid or gaseous cooling fluid.
Shaped conductors are, however, not free from challenges. One of the challenges is related to coil-ends where a conductor is adapted to implement an elevation between adjacent coil-turns. Figures 1a and 1 b illustrate a traditional coil 100 that comprises a coil-end 114 where a conductor of the coil is adapted to implement the elevation h between adjacent coil turns. In this exemplifying case, the conductor has a rectangular cross-section. Figure 1 c shows a conductor portion 120 separately. The viewing directions related to figures 1 a-1 c are indicated with a coordinate system 199. As shown in figure 1 c, the conductor has S-type curvature in the coil- end 114 so that the coil-end 114 has successive and oppositely directed curvatures R- ja R+. In many cases, the S-type curvature can be however challenging to implement so that its shape is accurately enough a shape needed for implementing the elevation between the adjacent coil-turns and for maintaining straight and parallel coil-sides which represent an active part of the coil 100. Summary
The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.
In this document, the word“geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional. An elongated object, e.g. an elongated conductor, is considered parallel with a two-dimensional geometric plane when the geometric tangent of the elongated object is at each point of the elongated object perpendicular to the geometric normal of the geometric plane.
In accordance with the invention, there is provided a new coil that can act as an element of a winding of an electric machine. A coil according to the invention comprises a conductor having a core portion and a layer of electrically insulating material surrounding the core portion. The core portion comprises electrically conductive material such as e.g. copper or aluminum for conducting electric current. The above-mentioned conductor is arranged to form coil portions having a same geometric magnetic axis and nested so that a first one of the coil portions is arranged to surround a second one of the coil portions. Each of the coil portions comprises:
- first conductor portions constituting first and second coil-sides of the coil portion,
- second conductor portions constituting a first coil-end between first ends of the first and second coil-sides, each of the second conductor portions being parallel with a first geometric plane perpendicular to the geometric magnetic axis, and the second conductor portions being one upon another in a direction of the geometric magnetic axis, and
- third conductor portions constituting a second coil-end between second ends of the first and second coil-sides so that the coil portion is arranged to follow a helical path.
The conductor further comprises one or more connecting portions that are parallel with the first geometric plane and connect the coil portions in series so that the helical paths related to adjacent ones of the coil portions have opposite handedness. The above-mentioned third conductor portions of each coil portion are crossed with respect to the corresponding third conductor portions of an adjacent coil portion so that the third conductor portions implement an elevation between successive conductor turns of the coil portions. Therefore, there is no need for S-type curvatures in the conductor. The third conductor portions of adjacent coil portions are crossed with respect to each other because the helical paths related to the adjacent coil portions have opposite handedness.
In this document, the term“helical path” is not limited to cases where a helical path has a constant radius of curvature and a constant slope of elevation, but the radius of curvature and/or the slope of elevation can vary along the helical path.
A coil according to an exemplifying and non-limiting embodiment of the invention comprises three or more nested coil portions of the kind described above.
In accordance with the invention, there is provided also a new machine element for an electric machine. The machine element can be for example a part of a stator or a part of a rotor of an electric machine. A machine element according to the invention comprises:
- a core element comprising a yoke section and teeth connected to the yoke section, slots being formed between adjacent ones of the teeth,
- coils according to the invention, each coil being arranged to surround one of the teeth of the core element and a coil-width of each coil being equal to the slot-pitch of the core element. In accordance with the invention, there is provided also a new method for manufacturing a coil according to the invention. The method comprises: shaping a conductor to form i) coil portions having a same geometric magnetic axis and nested so that a first one of the coil portions surrounds a second one of the coil portions and to form ii) one or more connecting portions connecting the coil portions in series, each of the coil portions comprising first conductor portions constituting first and second coil-sides, second conductor portions constituting a first coil-end between first ends of the first and second coil-sides, and third conductor portions constituting a second coil-end between second ends of the first and second coil-sides so that the coil portion follows a helical path, the connecting portions connecting the coil portions in series so that the helical paths related to the first and second ones of the coil portions have opposite handedness, pressing the first coil-ends of the coil portions between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil so that the second conductor portions of each of the coil portions are one upon another in a direction of the geometric magnetic axis, and bending the first coil-side of the first one of the coil portions and the second coil-side of the second one of the coil portions in a first direction parallel with the geometric magnetic axis without bending the second coil-side of the first one of the coil portions and the first coil-side of the second one of the coil portions in the first direction so as to align the second ends of the first and second coil-sides of the coil portions with respect to each other in the first direction. In accordance with the invention, there is provided also a new tool for shaping a coil according to the invention. The tool comprises:
- a first pressing member for pressing the first coil-ends of the coil portions between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil, and - a second pressing member comprising projections for bending the first coil- side of the first one of the coil portions and the second coil-side of the second one of the coil portions in a first direction parallel with the geometric magnetic axis without bending the second coil-side of the first one of the coil portions and the first coil-side of the second one of the coil portions in the first direction.
Various exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.
Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and non-limiting embodiments when read in conjunction with the accompanying drawings.
The verbs“to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of“a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.
Brief description of figures Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which: figures 1 a, 1 b, and 1 c illustrate a coil according to the prior art for a winding of an electric machine, figures 2a, 2b, and 2c illustrate a coil according to an exemplifying and non-limiting embodiment for a winding of an electric machine, figures 3a, 3b, and 3c illustrate a coil according to another exemplifying and non limiting embodiment for a winding of an electric machine, figure 4a shows a flowchart of a method according to an exemplifying and non limiting embodiment for manufacturing a coil of a winding of an electric machine, figures 4b, 4c, 4d, 4e, 4f, and 4g illustrate an exemplifying coil after method stages presented in figure 4a, wherein figures 4c-4f illustrate also a tool according to an exemplifying and non-limiting embodiment for shaping a coil, figure 5 illustrates a detail of a tool according to another exemplifying and non limiting embodiment for shaping a coil, and figure 6 illustrates a machine element according to an exemplifying and non-limiting embodiment. Figures 1 a-1 c have been explained in the Background-section of this document.
Description of exemplifying and non-limiting embodiments
The specific examples provided in the description below should not be construed as limiting the scope and/or the applicability of the accompanied claims. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated.
Figure 2a shows a top view of a coil 200 according to an exemplifying and non limiting embodiment. Figure 2b shows a view of a section taken along a line A-A shown in figure 2a so that the section plane is parallel with the yz-plane of a coordinate system 299. Figure 2c shows a view of a section taken along a line B-B shown in figure 2a so that the section plane is parallel with the yz-plane of the coordinate system 299. The viewing directions related to figures 2b and 2c are indicated by the coordinate system 299. The coil 200 comprises a conductor 201 comprising a core portion and a layer of electrically insulating material surrounding the core portion. The core portion and the layer of electrically insulating material are denoted with references 226 and 227 in the section view shown in figure 2b. The core portion comprises electrically conductive material such as e.g. copper or aluminum for conducting electric current. The core portion 226 may comprise for example a bundle of filamentary conductors. In this exemplifying case, the cross- sectional profile of the conductor 201 is determined by the layer of the electrically insulating material 227 surrounding the core portion and/or by resin or other filler material among the filamentary conductors. The bundle of the filamentary conductors may comprise for example one or more Litz-wires where the filamentary conductors are individually insulated and twisted and/or woven together. For another example, the core portion can be a single conductor bar, e.g. a copper bar. For a third example, the core portion may comprise many conductor bars which have rectangular cross-sectional profiles and are positioned with respect to each other so that a desired cross-sectional profile of the conductor is achieved. The conductor bars can be electrically insulated from each other.
The conductor 201 is arranged to form coil portions 202 and 203 that have a same geometric magnetic axis 217 and are nested so that a first one 202 of the coil portions is arranged to surround a second one 203 of the coil portions. The geometric magnetic axis 217 is parallel with the z-axis of the coordinate system 299. Each of the coil portions 202 and 203 comprises first conductor portions 205 constituting first and second coil-sides of the coil portion under consideration. In figure 2a, the first and second coil-sides of the coil portion 202 are denoted with references 206 and 207 and the first and second coil-sides of the coil portion 203 are denoted with references 208 and 209. Each of the coil portions 202 and 203 comprises second conductor portions 210 that constitute a first coil-end between first ends of the first and second coil-sides of the coil portion under consideration. In figure 2a, the first coil-end of the coil portion 202 is denoted with a reference 21 1 and the first coil-end of the coil portion 203 is denoted with a reference 212. As shown in figures 2a and 2b, each of the second conductor portions 210 is parallel with a first geometric plane perpendicular to the geometric magnetic axis 217, and the second conductor portions 210 of each coil portion are one upon another in a direction of the geometric magnetic axis 217. The first geometric plane is parallel with the xy-plane of the coordinate system 299. Each of the coil portions 202 and 203 comprises third conductor portions 213 that constitute a second coil-end between second ends of the first and second coil-sides of the coil portion under consideration so that the coil portion is arranged to follow a helical path. In figure 2a, the second coil-end of the coil portion 202 is denoted with a reference 214 and the second coil-end of the coil portion 203 is denoted with a reference 215. Figure 2c shows the above-mentioned third conductor portions 213 so that the third conductor portions of the coil portion 203 are depicted with solid lines and the third conductor portions of the coil portion 202 are depicted with dashed lines.
The conductor 201 further comprises a connecting portion that connects the above- mentioned coil portions 202 and 203 in series so that the helical paths related the coil portions 202 and 203 have opposite handedness. In figure 2c, the connecting portion is denoted with a reference 218. As illustrated in figure 2c, the connecting portion 218 is parallel with the xy-plane of the coordinate system 299 and the above- mentioned third conductor portions of the coil portion 202 are crossed with respect to the corresponding third conductor portions of the coil portion 203. The third conductor portions of the coil portions 202 and 203 are crossed with respect to each other because the helical paths related to the coil portions 202 and 203 have opposite handedness. As shown in figures 2a-2c, the helical paths do not have a constant radius of curvature nor a constant slope of elevation, but the radius of curvature and the slope of elevation vary along the helical paths. For example, the slope of elevation is zero on the second conductor portions 210 whereas the elevation differs from zero on the third conductor portions 213.
In the exemplifying coil 200 illustrated in figures 2a-2c, the coil-sides 206-209 are straight and the first coil-sides 206 and 208 of the coil portions 202 and 203 are parallel with the second coil-sides 207 and 209 of the coil portions. The above- described principle for implementing an elevation between successive turns of a coil is, however, applicable also on cases where coil-sides are curved and/or first and second coil-sides are non-parallel with each other. For example, an axial-flux electric machine may comprise coils where coil-sides are curved and/or first and second coil-sides are non-parallel with each other.
In a coil according to an exemplifying and non-limiting embodiment, the core portion of the conductor 201 comprises a tubular channel for conducting cooling fluid in a longitudinal direction of the conductor 201 . In figure 2b, the tubular channel is denoted with a reference 216. In the exemplifying coil 200, the core portion of the conductor 201 comprises a tube constituting the tubular channel. The tube can be made of material different from the electrically conductive material of the core portion of the conductor 201 . The tube can be made of e.g. steel. It is also possible that the core portion of the conductor 201 is a hollow bar of electrically conductive material, e.g. copper, and there is no separate tube inside the conductor.
Figure 3a shows a top view of a coil 300 according to an exemplifying and non limiting embodiment. Figure 3b shows a view of a section taken along a line A-A shown in figure 3a so that the section plane is parallel with the yz-plane of a coordinate system 399. Figure 3c shows a view of a section taken along a line B-B shown in figure 3a so that the section plane is parallel with the yz-plane of the coordinate system 399. The viewing directions related to figures 3b and 3c are indicated by the coordinate system 399. The coil 300 comprises a conductor 301 comprising a core portion and a layer of electrically insulating material surrounding the core portion.
The conductor 301 is arranged to form coil portions 302, 302, and 304 that have a same geometric magnetic axis 317 and are nested so that a first one 302 of the coil portions is arranged to surround a second one 303 of the coil portions and the second one 303 of the coil portions is arranged to surround a third one 304 of the coil portions. The geometric magnetic axis 317 is parallel with the z-axis of the coordinate system 399. Each of the coil portions 302-304 comprises first conductor portions 305 constituting first and second coil-sides of the coil portion under consideration. Each of the coil portions 302-304 comprises second conductor portions 310 that constitute a first coil-end between first ends of the first and second coil-sides of the coil portion under consideration. As shown in figures 3a and 3b, each of the second conductor portions 310 is parallel with a first geometric plane perpendicular to the geometric magnetic axis 317, and the second conductor portions 310 of each coil portion are one upon another in a direction of the geometric magnetic axis 317. The first geometric plane is parallel with the xy-plane of the coordinate system 399. Each of the coil portions 302-304 comprises third conductor portions 313 that constitute a second coil-end between second ends of the first and second coil-sides of the coil portion under consideration so that the coil portion is arranged to follow a helical path. Figure 3c shows the above-mentioned third conductor portions 313 so that the third conductor portions of the coil portion 304 are depicted with solid lines, the third conductor portions of the coil portion 303 are depicted with dashed lines, and the third conductor portions of the coil portion 302 are depicted with dash-and-dot lines.
The conductor 301 further comprises connecting portions that connects the above- mentioned coil portions 302-304 in series so that the helical paths related adjacent ones of the coil portions have opposite handedness. In figure 3c, the connecting portions are denoted with references 318 and 319. The connecting portion 319 is shown also in figure 3a. As illustrated in figure 3c, the connecting portions 318 and 319 are parallel with the xy-plane of the coordinate system 399 and the above- mentioned third conductor portions of adjacent coil portions, such as coil portions 304 and 303, are crossed with respect to each other. The third conductor portions of adjacent coil portions are crossed with respect to each other because the helical paths related to the adjacent coil portions have opposite handedness.
Figure 4a shows a flowchart of a method according to an exemplifying and non limiting embodiment for manufacturing a coil of a winding of an electric machine figures 4b, 4c, 4d, 4e, 4f, and 4g illustrate the coil after method stages presented in figure 4a. Furthermore, figures 4c-4g illustrate a tool for shaping the coil. A top view of the tool and the coil is shown in figure 4g. The method comprises a manufacturing phase 401 where a conductor is shaped to form nested coil portions and one or more connecting portions connecting the coil portions in series. The coil portions have a same geometric magnetic axis, and the coil portions are nested so that a first one of the coil portions surrounds a second one of the coil portions.
The coil after the manufacturing phase 401 is shown in figure 4b. In this exemplifying case there are first and second coil portions each of which comprises first conductor portions constituting first and second coil-sides, second conductor portions constituting a first coil-end between first ends of the first and second coil-sides, and third conductor portions constituting a second coil-end between second ends of the first and second coil-sides so that the coil portion follows a helical path. The above- mentioned connecting portions connect the first and second coil portions in series so that the helical paths related to the first and second coil portions have opposite handedness. In figure 4g, the first coil portion is denoted with a reference 402, the second coil portion is denoted with a reference 403, the first and second coil-sides of the coil portion 402 are denoted with references 406 and 407, the first and second coil-sides of the coil portion 403 are denoted with references 408 and 409, the first coil-end of the coil portion 402 is denoted with a reference 41 1 , the first coil-end of the coil portion 403 is denoted with a reference 412, the second coil-end of the coil portion 402 is denoted with a reference 414, and the second coil-end of the coil portion 403 is denoted with a reference 415.
The method further comprises a manufacturing phase 402 where the following actions are carried out simultaneously or successively:
- action 403: pressing the first coil-ends of the coil portions between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil so that the second conductor portions of each of the coil portions are one upon another in a direction of the geometric magnetic axis, and
- action 404: bending the first coil-side of the first one of the coil portions and the second coil-side of the second one of the coil portions in a first direction parallel with the geometric magnetic axis without bending the second coil- side of the first one of the coil portions and the first coil-side of the second one of the coil portions in the first direction so as to align the second ends of the first and second coil-sides of the coil portions with respect to each other in the first direction.
The above-mentioned action 403 is illustrated in figure 4c that shows a section taken along a line A-A shown in figures 4b and 4g so that the section plane is parallel with the yz-plane of a coordinate system 499. The tool for shaping the coil comprises a first pressing member 421 for pressing the first coil-ends 41 1 and 412 between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil. One of the planar pressing surfaces is a surface of the first pressing member 421 and the other of the planar pressing surfaces is a surface of an element 422.
The above-mentioned action 404 is illustrated in figures 4d-4f each of which shows a section taken along a line B-B shown in figures 4b and 4g so that the section plane is parallel with the yz-plane of the coordinate system 499. The tool for shaping the coil comprises a second pressing member 427 that comprises projections 428 and 429. As can be seen with the aid of figures 4d-4g, the second pressing member 427 is suitable for bending the first coil-side 406 of the coil portion 402 and the second coil-side 409 of coil portion 403 in a first direction parallel with the geometric magnetic axis without bending the second coil-side 407 of the coil portion 402 and the first coil-side 408 of the coil portion 403 in the first direction so as to align the second ends of the first and second coil-sides of the coil portions with respect to each other in the first direction. In the exemplifying case illustrated in figures 4b-4g, the first direction is the negative z-direction of the coordinate system 499. As shown in figures 4d, 4e, and 4g, connection ends 430 and 431 of the coil are arranged to be above the second pressing member 427. It is also possible that the connection end 430 is under the second pressing member 427. The connection end 431 is advantageously above the second pressing member 427 as shown in figures 4d, 4e, and 4g because, as shown in figure 4g, the connection end 431 crosses the second coil-end 414 of the first coil portion 402 and thereby a steep curve would be needed in the connection end 431 if the connection end 431 were under the second pressing member 427.
The tool for shaping the coil comprises means for producing forces for pressing the first and second pressing members 421 and 427 in the way described above with reference to figures 4c-4g. The means for producing the forces are not shown in figures 4c-4g, but the means can be for example mechanical, hydraulic, or electromechanical.
In a method according to an exemplifying and non-limiting embodiment, the first coil- side 406 of the coil portion 402 and the second coil-side 409 of the coil portion 403 are bend so that the second end of the first coil-side 406 of the coil portion 402 and the second end of the second coil-side 409 of the coil portion 403 pass a position where the second ends of the first and second coil-sides of the coil portions are aligned with respect to each other in the above-mentioned first direction so as to compensate for a spring-back effect occurring in the coil after the bending action.
The above-described exemplifying and non-limiting embodiment is illustrated in figure 4e that shows that the second pressing member 427 of the tool is suitable for bending the first coil-side 406 of the coil portion 402 and the second coil-side 409 of the coil portion 403 so that the second end of the first coil-side 406 of the coil portion 402 and the second end of the second coil-side 409 of the coil portion 403 pass the position where the second ends of the first and second coil-sides of the coil portions are aligned with respect to each other.
Figure 4f illustrates a situation where the second pressing member 427 has been removed after the bending action illustrated in figure 4e. The connection end 430 can be bent as shown in figure 4f. The connection end 431 has not been bent in the same way because, as shown in figure 4g, the connection end 431 crosses the second coil-end 414 of the first coil portion 402.
The exemplifying tool illustrated in figures 4c-4g comprises a support member 425 for protruding through a loop constituted by the coil. Furthermore, this exemplifying tool comprises support walls 423 and 424 for supporting the first and second coil- sides of the coil portions so that the coil is between the support walls and the geometric magnetic axis of the coil is parallel with the support walls.
In a method according to an exemplifying and non-limiting embodiment, a sliding membrane is installed in a gap between the second coil-ends 414 and 415 of the coil portions 402 and 403 prior to the bending action illustrated in figure 4e. In figure 4g, the gap is denoted with a reference 450. The sliding membrane facilitates the movement of the second coil-ends 414 and 415 with respect to each other during the above-mentioned bending action. It is also possible to install a sliding membrane in a gap between the coil-sides of the coil portions and/or in a gap between the first coil-ends 41 1 and 412 of the coil portions.
Figure 5 shows a section of a tool according to an exemplifying and non-limiting embodiment for shaping a coil. The section plane is parallel with the yz-plane a coordinate system 599. The section shown in figure 5 corresponds to the section shown in figure 4e. The exemplifying tool illustrated in figure 5 is suitable for shaping coils having three nested coil portions. The connecting ends of the conductor of the coil are denoted with references 530 and 531 . The pressing member 527 corresponds to the second pressing member 427 of the tool illustrated in figures 4c- 4g. Figure 6 illustrates a machine element 660 according to an exemplifying and non limiting embodiment of the invention. The machine element 660 can be for example a part of a stator of an inner rotor electric machine or a part of a rotor of an outer rotor electric machine. The axial direction of the electric machine is parallel with the z-axis of a coordinate system 699. The machine element 660 comprises a core element 661 comprising a yoke section 662 and teeth 663a, 662b, and 663c connected to the yoke section so that slots are formed between adjacent ones of the teeth. The machine element 660 comprises coils 600a, 600b, and 600c according to an embodiment of invention. Each coil is arranged to surround one of the teeth of the core element, and a coil-width of each coil is equal to the slot-pitch of the core element. Each coil can be for example such as illustrated in figures 2a- 2c or in figures 3a-3c.
The specific examples provided in the description given above should not be construed as limiting the applicability and/or interpretation of the appended claims. It is to be noted that lists and groups of examples given in this document are non- exhaustive lists and groups unless otherwise explicitly stated.

Claims

What is claimed is:
1. A coil (200, 300) for a winding of an electric machine, the coil comprising a conductor (201 , 301 ) comprising a core portion and a layer of electrically insulating material surrounding the core portion, the core portion comprising electrically conductive material and the conductor being arranged to form coil portions (202, 203, 302-304) having a same geometric magnetic axis and nested so that a first one (202) of the coil portions is arranged to surround a second one (203) of the coil portions, wherein each of the coil portions comprises:
- first conductor portions (205, 305) constituting first and second coil-sides (206, 207, 208, 209),
- second conductor portions (210, 310) constituting a first coil-end (211 , 212) between first ends of the first and second coil-sides, each of the second conductor portions being parallel with a first geometric plane perpendicular to the geometric magnetic axis, and the second conductor portions being one upon another in a direction of the geometric magnetic axis, and
- third conductor portions (213, 313) constituting a second coil-end (214, 215) between second ends of the first and second coil-sides so that the coil portion is arranged to follow a helical path, wherein the conductor comprises one or more connecting portions (218, 318, 319) connecting the coil portions in series so that the helical paths related to adjacent ones of the coil portions have opposite handedness, characterized in that the one or more connecting portions are parallel with the first geometric plane, and the third conductor portions of each of the coil portions are crossed with respect to the third conductor portions of an adjacent one of the coil portions.
2. A coil according to claim 1 , wherein the first and second coil-sides (206, 207,
208, 209) are straight.
3. A coil according to claim 2, wherein the first and second coil-sides (206, 207, 208, 209) are parallel with each other.
4. A coil according to any of claims 1 -3, wherein the coil portions (302-303) comprise at least three coil portions so that the first one (302) of the coil portions is arranged to surround the second one (303) of the coil portions and the second one (303) of the coil portions is arranged to surround a third one (304) of the coil portions.
5. A coil according to any of claims 1 -4, wherein the core portion of the conductor comprises a tubular channel (216) for conducting cooling fluid in a longitudinal direction of the conductor.
6. A coil according to claim 5, wherein the core portion of the conductor comprises a tube constituting the tubular channel (216) and being made of material different from the electrically conductive material.
7. A coil according to any of claims 1 -6, wherein the core portion of the conductor comprises a bundle of electrically parallel connected wires made of the electrically conductive material.
8. A machine element (660) for an electric machine, the machine element comprising:
- a core element (661 ) comprising a yoke section (662) and teeth (663a-663c) connected to the yoke section, slots being formed between adjacent ones of the teeth, and
- coils (600a-600c) according to any of claims 1 -7, wherein each coil is arranged to surround one of the teeth of the core element and a coil-width of each coil equals a slot-pitch of the core element.
9. A method for manufacturing a coil for a winding of an electric machine, the coil comprising a conductor comprising a core portion and a layer of electrically insulating material surrounding the core portion, the method comprising:
- shaping (401 ) the conductor to form i) coil portions having a same geometric magnetic axis and nested so that a first one of the coil portions surrounds a second one of the coil portions and to form ii) one or more connecting portions connecting the coil portions in series, each of the coil portions comprising first conductor portions constituting first and second coil-sides, second conductor portions constituting a first coil-end between first ends of the first and second coil-sides, and third conductor portions constituting a second coil-end between second ends of the first and second coil-sides so that the coil portion follows a helical path, the connecting portions connecting the coil portions in series so that the helical paths related to the first and second ones of the coil portions have opposite handedness, and
- pressing (403) the first coil-ends of the coil portions between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil so that the second conductor portions of each of the coil portions are one upon another in a direction of the geometric magnetic axis, characterized in that the method comprises bending (404) the first coil-side of the first one of the coil portions and the second coil-side of the second one of the coil portions in a first direction parallel with the geometric magnetic axis without bending the second coil-side of the first one of the coil portions and the first coil-side of the second one of the coil portions in the first direction so as to align the second ends of the first and second coil-sides of the coil portions with respect to each other in the first direction.
10. A method according to claim 9, wherein the first coil-side of the first one of the coil portions and the second coil-side of the second one of the coil portions are bend so that the second end of the first coil-side of the first one of the coil portions and the second end of the second coil-side of the second one of the coil portions pass a position where the second ends of the first and second coil-sides of the coil portions are aligned with respect to each other in the first direction so as to compensate for a spring-back effect occurring in the coil after the bending.
1 1 . A tool for shaping a coil according to any of claims 1 -7, the tool comprising a first pressing member (421 ) for pressing the first coil-ends of the coil portions between planar pressing surfaces perpendicular to the geometric magnetic axis of the coil, characterized in that the tool further comprises a second pressing member (427) comprising projections (428, 429) for bending the first coil-side of the first one of the coil portions and the second coil-side of the second one of the coil portions in a first direction parallel with the geometric magnetic axis without bending the second coil-side of the first one of the coil portions and the first coil-side of the second one of the coil portions in the first direction.
12. A tool according to claim 11 , wherein second pressing member (427) is configured to bend the first coil-side of the first one of the coil portions and the second coil-side of the second one of the coil portions so that the second end of the first coil-side of the first one of the coil portions and the second end of the second coil-side of the second one of the coil portions pass a position where the second ends of the first and second coil-sides of the coil portions are aligned with respect to each other in the first direction so as to compensate for a spring-back effect occurring in the coil after removal from the tool.
13. A tool according to claim 11 or 12, wherein the tool comprises a support member (425) for protruding through a loop constituted by the coil.
14. A tool according to any of claims 11 -13, wherein the tool comprises support walls (423, 424) for supporting the first and second coil-sides of the coil portions so that the coil is between the support walls and the geometric magnetic axis of the coil is parallel with the support walls.
PCT/FI2019/050826 2018-12-17 2019-11-19 A coil for a winding of an electric machine WO2020128147A1 (en)

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JP2014011221A (en) * 2012-06-28 2014-01-20 Sht Co Ltd Coil device having cooling structure
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