Abstract:
A rotating electrical machine stator comprising an annular cylindrical body including axial grooves, and at least one phase winding including corrugated turns of wire, the phase winding comprising a first outer half-phase and a second inner half-phase which are radially superimposed, the first outer half-phase including outer leading-out wires projecting from the radial walls of the body and the second inner half-phase including outer leading-out wires projecting from the radial walls of the body. The invention is characterized in that for each phase winding, the wire length of each turn of the inner half-phase is greater than the wire length of each turn of the outer half-phase. The invention also concerns a phase winding designed to be mounted in such a rotor.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a stator of a rotary electric machine which comprises a plurality of phase windings. 
         [0003]    The invention relates more particularly to a stator of a rotary electric machine, in particular an alternator or alternator-starter for a motor vehicle, comprising: 
         [0004]    an annular cylindrical body comprising axial slots which open axially into the front and rear axial end walls of the body and which are open radially into the inner cylindrical wall of the body; 
         [0005]    at least one phase winding which comprises corrugated turns of wire which comprise a series of axial strands which are received in a series of associated slots and connecting strands which connect the successive axial strands by protruding alternately with respect to the rear axial end wall and with respect to the front axial end wall;
       at least one phase winding comprises a first outer half-phase forming a first outer layer of turns which is received in the bottom of the slot, and a second inner half-phase forming a second inner layer of turns which are radially superposed, the connecting strands of the first outer half-phase forming outer coil ends and the connecting strands of the second inner half-phase forming inner coil ends, the inner and outer coil ends protruding axially with respect to the front and rear axial end walls of the body.       
 
         [0007]    2. Description of the Related Art 
         [0008]    The stators are already known in particular from the document FR-A-2.819.118. 
         [0009]    In general, the number of slots on a stator is equal to three times the number of phase windings multiplied by the number of poles of the rotor. 
         [0010]    Thus, for a stator which comprises three phase windings, known as a “three-phase” stator, and which comprises twelve poles, the body of the stator comprises thirty-six slots, and each phase winding is received in a series of twelve slots. Two consecutive slots of a series are arranged in such a way as to have between them two adjacent free slots, each free slot belonging to another series of slots which is associated with another phase. 
         [0011]    When mounting each phase winding in the body of the stator, the axial strands of each phase winding are inserted in the slots of the associated series of slots via the open axial grooves in the inner cylindrical wall of the stator body. 
         [0012]    The insertion of each phase winding must not be hampered by the coil ends of the other phase windings. The coil ends are therefore pushed radially outwards so as to free up some space axially opposite the open orifices of the slots in the axial end walls. 
         [0013]    However, some stators have a body which comprises a greater number of slots, each of which is of reduced size. 
         [0014]    This is the case with three-phase stators comprising sixteen poles. The body of the stator then comprises forty-eight slots. 
         [0015]    This is also the case with a stator comprising six phase windings, known as a “six-phase” stator. In this type of stator, the transverse width of the slots is essentially divided by two compared to the slots of a three-phase stator of the same diameter with twelve poles. 
         [0016]    Furthermore, the number of coil ends is multiplied by two. It therefore becomes difficult to insert a phase winding without being hampered by the coil ends of the other phase windings. 
       SUMMARY OF THE INVENTION 
       [0017]    The invention therefore proposes a stator comprising for each phase winding, the length of wire of each turn of the inner half-phase is greater than the length of wire of each turn of the outer half-phase, such that the protruding axial height of the inner coil ends is greater than the protruding axial height of the outer coil ends. 
         [0018]    According to other features of the invention: 
         [0019]    the protruding axial height of the inner coil ends and of the outer coil ends is such that the coil ends are able to be folded radially towards the outer periphery of the stator body so as to free the open axial ends of the intermediate slots which do not form part of the series of slots associated with said winding; 
         [0020]    the protruding axial height of the outer coil ends is substantially equal to the axial height of the inner coil ends plus a height that is generally equal to the radial thickness occupied by the axial strands of the outer half-phase in each associated slot; 
         [0021]    the turns of each half-phase are oppositely corrugated; 
         [0022]    the stator comprises six phase windings, and two successive slots of each series being spaced apart by five adjacent intermediate slots; and 
         [0023]    the stator comprises three phase windings, and two successive slots of each series being spaced apart by two adjacent slots. 
         [0024]    The invention also relates to a phase winding which is designed to be mounted by axial deformation on a stator body so as to obtain a stator according to the teachings of the invention, of the type in which the phase winding comprises an axial superposition of turns in the form of regular stars, each turn comprising radial strands of equal length and inner and outer transverse connecting strands, of the type in which the radial strands are designed to be received in the axial slots of the stator body so as to form the axial strands of the mounted winding, while the transverse connecting strands are designed to form the coil ends of the mounted winding, and of the type in which the phase winding comprises a first rear half-phase forming a rear layer of turns, and a second front half-phase forming a front layer of turns, the front half-phase being designed to form the outer half-phase of the mounted winding and the rear half-phase being designed to form the inner half-phase of the mounted winding, characterized in that the length of wire of each turn of the rear half-phase is greater than the length of wire of each turn of the front half-phase. 
         [0025]    According to other features of the phase winding according to the invention: 
         [0026]    the length of wire of each turn of the rear half-phase is 2% to 10% greater than the length of wire of each turn of the front half-phase; 
         [0027]    the length of wire of each turn of the rear half-phase is generally equal to the length of wire of each turn of the front half-phase plus the axial thickness of the front half-phase multiplied by the number of radial strands; 
         [0028]    the length of each radial strand of each turn of the rear half-phase is equal to the length of a radial strand of one of the turns of the front half-phase plus the axial thickness of the rear half-phase; 
         [0029]    the star-shaped contour of the front half-phase is offset angularly about the central axis with respect to the star-shaped contour of the rear half-phase, so that the branches of the upper star extend radially between two branches of the lower star; 
         [0030]    the two half-phases are wound in an opposite direction with respect to one another. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    Other features and advantages of the invention will become apparent upon reading the following detailed description, for the comprehension of which reference will be made to the appended drawings, in which: 
           [0032]      FIG. 1  is a plan view which shows a stator body that is already known which is designed to receive phase windings; 
           [0033]      FIG. 2  is a perspective view on a large scale which shows a sector of the stator body of  FIG. 1  in which a phase winding formed according to the prior art has been mounted; 
           [0034]      FIG. 3  is a sectional view along the section plane  3 - 3  in  FIG. 2  which shows two coil ends of the phase winding before they have been pushed back radially; 
           [0035]      FIG. 4  is a perspective view which shows the phase winding of  FIG. 2  before it is mounted on the stator body of  FIG. 1  which is in accordance with the prior art; 
           [0036]      FIG. 5  is an exploded plan view which shows the two half-phases of the phase winding of  FIG. 2  before mounting which is in accordance with the prior art; 
           [0037]      FIG. 6  is a plan view which shows the phase winding according to the prior art in which the two half-phases are axially superposed; 
           [0038]      FIG. 7  is a view similar to that of  FIG. 3  in which the outer coil end has been pushed back radially against the yoke of the stator body; 
           [0039]      FIG. 8  is a view similar to that of  FIG. 3  in which the outer and inner coil ends have been pushed back radially against the yoke of the stator body; 
           [0040]      FIG. 9  is an exploded plan view which shows the two half-phases of a phase winding before mounting in the stator body of  FIG. 1  which is formed according to the teachings of the invention; 
           [0041]      FIG. 10  is a plan view which shows the winding of  FIG. 9  in which the two half-phases are axially superposed; 
           [0042]      FIG. 11  is a plan view which shows a sector of a stator body in which the winding of  FIG. 10  has been mounted and in which the coil ends of the phase winding have been pushed back radially towards the outside; 
           [0043]      FIG. 12  is a sectional view along the section plane  12 - 12  in  FIG. 11  which shows two coil ends of the phase winding before they have been pushed back radially towards the outside; 
           [0044]      FIG. 13  is a view similar to that of  FIG. 12  in which one of the coil ends has been pushed back radially towards the outside; and 
           [0045]      FIG. 14  is a view similar to that of  FIG. 7  in which the two coil ends have been pushed back radially towards the outside 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0046]    In the text below, elements which are identical, similar or analogous will be designated by the same reference numerals. 
         [0047]    For the rest of the description, and in a non-limiting manner, there will be adopted an axial orientation which is aimed from the back towards the front as indicated by the arrow F in the figures. 
         [0048]      FIG. 2  shows a rotary electric machine stator  11  formed according to the prior art which comprises principally a stator body  10  in which a plurality of phase windings  30  are mounted. 
         [0049]    In order to simplify the comprehension of the figures, the stator  11  has been shown with a single phase winding  30 , but such a stator  11  comprises six phase windings which are analogous to the one shown in  FIG. 2 . 
         [0050]      FIG. 1  shows the stator body  10  of the rotary electric machine stator  11 . The rotary machine is for example an alternator or an alternator-starter. This machine is preferably intended to be used in a motor vehicle. 
         [0051]    It will be recalled that an alternator-starter is a rotary electric machine which is able to operate in a reversible manner, on the one hand as an electric generator in an alternator function and on the other hand as an electric motor in particular for starting the heat engine of the motor vehicle. Such an alternator-starter is described for example in the document WO-A-01/69762 corresponding to U.S. Pat. No. 7,224,093, to which reference may be made for further details and which is incorporated herein by reference and made a part thereof. 
         [0052]    The stator body  10  has an annular cylindrical shape of axis A. 
         [0053]    In the rest of the text, orientations which are orthogonal to the axis A and secant with the axis A will be referred to as radial orientations. Orientations which are orthogonal both to the axis A and to a radial orientation will be referred to as transverse orientations. 
         [0054]    The stator body  10  is delimited radially by an inner cylindrical wall  12  and by an outer cylindrical wall  14 , and it is delimited axially by a radial front axial end wall  16  and by a radial rear axial end wall  18 . 
         [0055]    The stator body  10  comprises axial slots  20  which open axially into the radial front  12  and rear  14  axial end walls of the stator body  10  via front  22  and rear  24  axial orifices. 
         [0056]    The transverse width of the slots  20  is smaller than the radial length thereof. 
         [0057]    The slots  20  are open radially into the inner cylindrical wall  12  of the stator body  10  via an axial groove  26  which extends from the radial front axial end wall  16  to the radial rear axial end wall  18 . The transverse width of each axial groove  26  is smaller than the width of the associated slot  20 . 
         [0058]    The slots  20  are all identical, and there are seventy-two of them for example. They are distributed at regular angular intervals about the axis A of the stator body  10 . 
         [0059]    The solid outer annular portion of the stator body  10 , in which the slots  20  do not extend, is referred to as the yoke  28 . 
         [0060]    As shown in  FIG. 2 , in order to form the stator  11 , phase windings  30  are mounted in the stator body  10 . 
         [0061]    The invention will be described with reference to a stator comprising six phase windings  30 , also known as a “six-phase” stator. 
         [0062]    However, the invention is applicable to stators comprising a different number of phase windings, and in particular to “three-phase” stators comprising three phase windings  30 . The stator body  10  then comprises for example thirty-six or forty-eight slots  20 . 
         [0063]    Each phase winding  30  comprises corrugated turns  32  formed by an electrically conductive wire  33 . 
         [0064]    According to one variant of the invention, each phase winding  30  comprises corrugated turns  32  which are formed by a bundle of at least two conductive wires. 
         [0065]    Thus, as shown in  FIG. 2 , each phase winding  30  comprises corrugated turns  32  of wire  33  which comprise a series of axial strands  34  which are received in a series of associated slots  20 . 
         [0066]    Connecting strands  36  of generally transverse orientation which connect the successive axial strands  34  protrude alternately with respect to the radial rear axial end wall  18  and with respect to the radial front axial end wall  16 . 
         [0067]    As shown in  FIG. 2 , the slots  20  of the series of slots receive the axial strands  34  of the turns  32  constituting a phase winding  30 . Each axial strand  34  is able to be introduced into the associated slot  20  via the axial groove  26 , as will be described below. 
         [0068]    Each series of slots is associated with one of the six phase windings  30 . Two consecutive slots  20  of a series of slots  20  are separated by adjacent slots  20 , each corresponding to another series of slots  20  which is associated with one of the five other phase windings  30 . 
         [0069]    Thus, for a six-phase stator as is the case in  FIG. 2 , five adjacent slots are left free between two slots  20  of each series. In other words, the wires  33  of one winding are inserted in one slot  20  out of six adjacent slots  20 . 
         [0070]    Thus, for a stator comprising N phase windings  30 , the axial strands  34  of a turn  32  are received in one slot  20  out of N adjacent slots  20 . 
         [0071]    Each phase winding  30  of the stator  11  comprises a first outer half-phase  38 E forming a first outer layer of turns  32  and a second inner half-phase  38 I forming a second inner layer of turns  32 . The axial strands  34  of the outer half-phase  38 E are superposed radially with the axial strands  34  of the inner half-phase  38 I, as shown in  FIG. 2 . 
         [0072]    The connecting strands  36 E of the first outer half-phase  38 E form outer coil ends  40 E and the connecting strands  361  of the second inner half-phase  38 I form inner coil ends  40 I. The inner  40 I and outer  40 E coil ends protrude axially with respect to the front  16  and rear  18  axial end walls of the stator body  10 . 
         [0073]    The coil ends  40 I of the inner half-phase  38 I extend in an axial direction alternately from the front  16  and rear  18  radial walls of the stator body  10 , thus forming front and rear first annuli. 
         [0074]    The coil ends of the outer half-phase  38 E extend in an axial direction alternately from the front  16  and rear  18  radial walls of the stator body  10 , thus forming front and rear second annuli. 
         [0075]    The two half-phases  38 E,  38 I are oppositely corrugated. Thus, the second annuli have a smaller diameter than the first annuli, and they are offset angularly with respect to these first annuli about the axis A. 
         [0076]    This type of phase winding  30  is also known by the name “distributed wave winding”. 
         [0077]    As shown in  FIG. 3  and in a known manner, each of the coil ends  40 E,  40 I of each half-phase  38 E,  38 I protrudes with respect to the front  16  or rear  18  radial wall by a substantially equal axial height H. 
         [0078]    For the rest of the description, the axial height H of a coil end  40 E,  40 I will be described as the axial distance between the radial wall of the stator body  10  from which the coil end  40 E,  40 I extends axially and the most remote point of the inner arch formed by the coil end  40 I,  40 E. 
         [0079]    A known method for inserting the phase windings  30  in the stator body  10  is briefly described below. A detailed description of such an insertion method is described in detail for example in the document FR-A-2.846.481, in particular in pages 8 to 11 of this document. 
         [0080]    In order to distinguish a phase winding before mounting on the stator body  10  from a phase winding mounted on the stator body  10 , the reference winding before mounting will have the reference numeral  50  whereas the same phase winding in the mounted state will have the reference numeral  30 . 
         [0081]      FIG. 4  shows a phase winding  50  before being mounted in the slots  20  of the stator body  10 . This non-mounted phase winding  50  is already known and makes it possible to obtain a known stator  11  as described above. 
         [0082]    Here, the non-mounted phase winding  50  is made from an electrically conductive wire  33 , such as a copper wire. The phase winding  50  has an axis which is coaxial with the axis A of the stator body  10 . 
         [0083]    This non-mounted phase winding  50  comprises front  58 A and rear  58 B half-phases which are shown in  FIG. 3 . These front  58 A and rear  58 B half-phases correspond respectively to the outer  38 E and inner  38 I half-phases of the mounted phase winding  30 . 
         [0084]    Each half-phase  58 A,  58 B comprises a superposition of identical flat turns  52  in the form of regular stars of axis A. The turns  52  of a given half-phase  58 A,  58 B superpose one another perfectly. 
         [0085]    As shown in  FIG. 3 , the turns  52  of the front half-phase  58 A are wound in a first, clockwise direction while the turns  52  of the rear half-phase  58 B are wound in a second, anti-clockwise direction. 
         [0086]    Each turn  52  of a half-phase  58 A,  58 B comprises a plurality of radial strands  62  of equal length which are oriented substantially radially with respect to the axis A. There is an even number of radial strands  62 , and more particularly here there are twelve of them. 
         [0087]    The radial strands  62  are connected alternately to one another by inner  56 I and outer  56 E transverse connecting strands in such a way that pairs of two successive radial strands  62  form the branches of a regular star which here has six branches. 
         [0088]    The radial strands  62  are designed to constitute the axial strands  34  of the mounted phase winding  30 , whereas the inner  56 I and outer  56 E transverse strands are designed to constitute the transverse strands  36 E,  36 I of the coil ends  40 E,  40 I of the mounted phase winding  30 . 
         [0089]    As shown in  FIG. 5 , the radial length of the radial strands  62  is substantially greater than the axial length of each slot  20  of the stator body  10 . 
         [0090]    The inner transverse strands  56 I extend on an imaginary inner circle which is centered on the axis A and which has a diameter D 1  that is substantially smaller than the inner diameter of the stator body  10 . 
         [0091]    The outer transverse strands  56 E extend generally on an imaginary outer circle which is centered on the axis A and which has a diameter D 2  that is substantially greater than the inner diameter of the stator body  10 . 
         [0092]    The two half-phases  58 A,  58 B are electrically connected to one another by a connecting wire  46 . 
         [0093]    Advantageously, the two half-phases  58 A,  58 B and the connecting wire  46  consist of a single wire  33  or of a single bundle of at least two parallel wires. 
         [0094]    As shown in  FIG. 6 , the front half-phase  58 A is placed in front of the rear half-phase  58 B. The axes of symmetry of the two half-phases  58 A,  58 B are coaxial with the axis A of the stator body  10 , such that the front half-phase  58 A is offset axially towards the front relative to the rear half-phase  58 B. 
         [0095]    The rear half-phase  58 B thus forms a rear layer of turns  52  while the front half-phase  58 A forms a front layer of turns  52 . 
         [0096]    As shown in  FIG. 6 , the turns  52  of the front half-phase  38 Ea are offset angularly about the axis A relative to the turns  32   a  of the rear half-phase  38 Ia, each branch of the front half-phase  38 Ea thus being inserted angularly between two branches of the rear half-phase  38 Ia. 
         [0097]    This phase winding  50  is then mounted by deformation on the stator body  10  using the mounting method which comprises in particular the following steps. 
         [0098]    During a first positioning step, the phase winding  50  is arranged against the radial rear axial end wall  18  of the stator body  10 , the star-shaped turns  52  being coaxial to the axis A of the stator body  10  and extending in planes which are substantially perpendicular to this axis A. 
         [0099]    The front half-phase  58 A is positioned closer to the radial rear axial end wall  18  than the rear half-phase  58 B. A portion of each radial strand  62  of the turns  52  is arranged opposite an associated slot  20 . 
         [0100]    During a second step of insertion via deformation, the front  58 A and rear  58 B half-phases are inserted in the slots  20  by progressively twisting the radial strands  62  of the turns  52  axially from the back to the front and by simultaneously tilting all the radial strands  62  towards a direction parallel to the axis A. 
         [0101]    This deformation is obtained for example by making an insertion block (not shown) slide axially from the back to the front inside the stator body  10  so that, during its sliding movement, the insertion block presses against the inner transverse strands  541  in order to cause the tilting of the radial strands  62 . 
         [0102]    The radial strands  62  of each turn  52  initially extend in a radial plane perpendicular to the axis A. During the tilting thereof, each radial strand  62  is inserted in the slot  20  located opposite via the axial groove  26 . 
         [0103]    The radial strands  62  are then inserted in the slots  20  over almost their entire length. In the mounted position in the stator body  10 , the radial strands  62  then have an axial orientation. These radial strands  62  then correspond to the axial strands  34  of the stator  11 . 
         [0104]    The axial strands  34  of the outer half-phase  38 E, corresponding to the radial strands  62  of the front half-phase  58 A, are then arranged radially at the bottom of each slot  20 , close to the yoke  28  of the stator body  10 , while the axial strands  34  of the inner half-phase  38 I, corresponding to the axial strands  62  of the rear half-phase  58 B, are arranged radially close to the axial groove  26 . 
         [0105]    Similarly, the inner transverse strands  56 I of the turns  52  then form the coil ends  40 E,  40 I which protrude with respect to the radial front axial end wall  16  of the stator body  10 , and the outer transverse strands  56 E of the turns  52  then form the coil ends  40 E,  40 I which protrude with respect to the radial rear axial end wall  18  of the stator body  10 . 
         [0106]    The mounting steps are then repeated for the other phases of the stator. 
         [0107]    As shown in  FIGS. 7 and 8 , in order to allow the insertion of the other phases, the coil ends  40 E,  40 I of the mounted phase winding  30  are pushed back radially towards the outside in order to free the axial orifices  22 ,  24  of the free slots  20  which do not form part of the series of slots  20  associated with this phase winding  30 . 
         [0108]    The loops of the coil ends  40 E,  40 I then extend in a plane which is substantially radial with respect to the axis A, so as to frame the axial orifices  22 ,  24  of the slots  20  in the two transverse directions and in a radial direction towards the outside. 
         [0109]    This operation makes it possible to free the axial orifices  22 ,  24  of the slots  20  so as not to hamper the insertion of the other phases, and in particular so as not to interfere with the coil ends  40 E,  40 I of the other phases. 
         [0110]    However, before being pushed back, the outer coil ends  40 E have substantially the same axial height as the inner coil ends  40 I. Part of the axial height H of the outer coil ends  40 E is therefore superfluous, that is to say that in the pushed-back position, as shown in  FIGS. 7 and 8 , the outer coil ends  40 E protrude radially by a length L with respect to the inner coil ends that have been pushed back radially. This means an unnecessary use of wire and an unnecessary bulk of the outer coil ends  40 E. 
         [0111]    The invention therefore proposes a phase winding  30  which, when it is mounted in the stator body  10 , makes it possible to obtain a stator  11  in which the axial height of the outer coil ends  40 E is smaller than the axial height of the inner coil ends  40 I. 
         [0112]    In order to obtain such a stator, the invention proposes a non-mounted phase winding  50  in which the length of wire  33  of each turn  52  of the rear half-phase  58 B is greater than the length of wire  33  of each turn  52  of the front half-phase  58 A. 
         [0113]    Thus,  FIGS. 9 and 10  show a phase winding  50  before it is mounted in the stator body  10 . This non-mounted phase winding  50  is formed according to the teachings of the invention. 
         [0114]    For each half-phase  58 A,  58 B, the radial strands  62  have an identical length. However, the radial strands  62  of the rear half-phase  58 B are longer than the radial strands  62  of the front half-phase  58 A. 
         [0115]    More particularly, the length of the radial strands  62  of the rear half-phase  58 B is such that the inner transverse strands  56 I of the rear half-phase  58 B are arranged on an inner circle centered on the axis A, the diameter D 3  of which is smaller than the diameter D 1  of the inner circle on which there extend the inner transverse strands  56 I of the front half-phase  58 A. 
         [0116]    Furthermore, the outer transverse strands  56 E of the rear half-phase  58 B are arranged on a circle centered on the axis A, the diameter D 4  of which is greater than the diameter D 2  of the circle on which there extend the outer transverse strands  56 E of the front half-phase  58 A. 
         [0117]    Thus, as shown in  FIG. 10 , the radial strands  62  of the rear half-phase  58 B protrude radially inwards and outwards with respect to the radial strands  62  of the front half-phase  58 A. 
         [0118]    More particularly, the length of the radial strands  62  of the rear half-phase  58 B of the phase winding  30  is here equal to the length of the radial strands  62  of the front half-phase  38 E plus the radial thickness ER that the axial strands  34  will occupy in an associated slot  20  when the phase winding  50  is mounted in the stator body  10 . 
         [0119]    This radial thickness ER corresponds generally to the axial thickness EA occupied by the radial strands  62  of the front half-phase  58 A of the phase winding  50  before it is mounted in the stator body  10 . 
         [0120]    In other words, the length of wire  33  of each turn  52  of the rear half-phase  58 B is generally substantially equal to the length of wire  33  of each turn  52  of the front half-phase  58 A plus the axial thickness of the front half-phase  58 A multiplied by the number of radial strands  62 . 
         [0121]    For example, the length of wire  33  of each turn  52  of the rear half-phase  58 B is 2% to 10% greater than the length of wire of each turn  52  of the front half-phase  58 A. 
         [0122]    As shown in  FIG. 13 , when a phase winding  50  formed according to the teachings of the invention is mounted on the stator body  10 , the inner coil ends  40 I have an axial height HI which is greater than the axial height HE of the outer coil ends  40 E. This greater axial height HE of the outer coil end  40 E is conferred by the greater length of the axial strands  34  of the inner half-phase  38 I. 
         [0123]    As shown in  FIG. 13 , the axial height HE of the outer coil end  40 E is such that the transverse strands  36 I of the inner half-phase  38 I extend in alignment with the yoke  28  of the stator body  10 , substantially on the same circle as the transverse strands  36 E of the outer half-phase  38 E. 
         [0124]    In order to obtain this result, the axial height HI of the inner coil ends  40 I is equal to the axial height of the outer coil ends  40 E plus substantially the radial thickness occupied by the axial strands  34  of the outer half-phase  38 E in each associated slot  20 . 
         [0125]    Thus, when the coil ends  40 E,  40 I are pushed back radially towards the outside, as shown in  FIG. 11  and also in  FIGS. 13 and 14 , the slots  20  are perfectly freed, but none of the coil ends  40 E,  40 I protrudes radially outwards from the stator body  10 . More specifically, the coil ends  40 E and  40 I are at the same radial distance from the slots  20 . 
         [0126]    Thus, the outer coil end  40 E has an axial height such that, when it is pushed back radially, as shown in  FIG. 8 , the coil end  40 E is arranged axially in alignment with the yoke  28  of the stator body  10 , thereby freeing the space which extends axially in front of the free slots  20  of the front radial wall. 
         [0127]    The invention has been described with reference to a method in which the phase windings  30   a  are mounted successively one after the other in the stator body  10 . However, the invention is also applicable for mounting methods in which at least two phase windings  30   a , or even all the phase windings  30   a , are mounted simultaneously in the stator body  10 . 
         [0128]    While the form of apparatuses herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to these precise forms of apparatuses, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.