Abstract:
A rotating electrical machine having cooperating rotor and stator, one of which forms a plurality of pole teeth around which individual coils are wound. The coils are connected in a number depending upon the phase and number of poles and the connected coils of each phase are spaced from each other. Crossover wires connect these coil windings of each phase and the crossover wires are affixed by bonding to outstanding tabs that are formed on the outermost laminations of the assembly. This reduces hand labor and insures that the crossover wires will not interfere with other components of the machine or associated driving or driven structures.

Description:
BACKGROUND OF INVENTION  
         [0001]    This invention relates to an improved stator for rotary electrical equipment and more particularly to an improved coil winding arrangement for multi-phase equipment of this type.  
           [0002]    In connection with rotating electrical machines, it is common practice to employ a series of circumferential spaced permanent magnets which cooperate with pole teeth around which coil windings are formed in order to either produce electrical power when the machine is a generator or to provide a driving force when the machine is a motor. The coil windings are wound around the pole teeth. When multi-phase winding is employed, certain coils are placed on adjacent pole teeth and then a number of coils is skipped for each phase before the next series of coils is wound for the phase.  
           [0003]    A wire called a “crossover wire” connects the groups of coil windings of each phase.  
           [0004]    A disadvantage with this type of construction is that the crossover wires must be dealt with. That is, they must be positioned in such a way so that the crossover wires are not accidentally placed in a position where they may be damaged. This requires hand placement of the crossover wires and greatly impedes the ability to expedite production. It is therefore the practice to provide some form of clamping arrangement that fixes these crossover wires to the stator core or to the housing of the machine, thus requiring manual labor.  
           [0005]    Also, there is a problem in connection with the tying down or holding of these crossover wires so they do not become displaced when the machine is on operation. This also necessitates the tying down of the crossover wires.  
           [0006]    It is, therefore, a principal object to this invention to provide an improved rotating electrical machine having phase windings and wherein the crossover wires connecting the coils of the individual phases are rigidly held in position and without manual operation.  
           [0007]    It a further object to this invention to provide an improved coil winding arrangement for a multi-phase rotating electrical machine.  
         SUMMARY OF INVENTION  
         [0008]    This invention is adapted to be embodied in a coil winding arrangement for a rotating electrical machine. The winding arrangement is comprised of a core comprised of a plurality of laminated plates each having a cylindrical portion from which a plurality of circumferentially spaced, pole tooth forming portions extend in a generally radial direction. The plurality of laminated plates are held in abutting relation with their pole tooth forming portions aligned to form a plurality of cores. A plurality of phase windings are wound on the core. Each of these phase windings are wound around a series of the cores arranged in groups of adjacent cores. The groups of cores are spaced by cores around which other of the phase windings are wound. The windings of each group of each of the phases are connected to each other by crossover wires to provide the electrical connection between the coils of the groups of adjacent cores. An axial outermost of the laminated plates is formed with outstanding tabs at circumferentially spaced locations against which said crossover wires lie.  
           [0009]    In accordance with another feature of the invention, the crossover wires are adhesively bonded to the tabs by an insulating material. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0010]    [0010]FIG. 1 is a cross sectional view taken through a portion of an internal combustion engine associated with a rotating electrical machine constructed in accordance with an embodiment of the invention.  
         [0011]    [0011]FIG. 2 is an end elevational view of the rotating machine and showing the coil winding arrangement for a single phase.  
         [0012]    [0012]FIG. 3 is a view looking in the same direction as FIG. 2 but shows all of the phases of the winding.  
         [0013]    [0013]FIG. 4 is a view, in part similar to FIGS. 2 and 3, but shows the finished coil winding arrangement.  
         [0014]    [0014]FIG. 5 is a cross sectional view taken along the line  5 - 5  of FIG. 4 but with the windings eliminated.  
         [0015]    [0015]FIG. 6 is a partially exploded perspective view showing the armature core.  
         [0016]    [0016]FIG. 7 is a view looking in the same direction as FIG. 2 and in part similar to this figure but showing another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0017]    Referring now in detail to the drawings and initially primarily to FIG. 1, an embodiment of the invention is shown as associated with an internal combustion engine, indicated generally by the reference numeral  11 . The invention is shown in conjunction with an internal combustion engine  11  because this is a typical environment in which the invention can be utilized although the use is not so limited.  
         [0018]    One reason why this invention has particular utility with internal combustion engines is that it permits a compact rotating electrical machine and one, which can be machined and produced in high production volumes at a low cost because the amount of manual labor involved is substantially minimized.  
         [0019]    Only a portion of the engine  11  is shown and where any details of the engine are not illustrated or described, those skilled in the art will readily understand how the invention can be applied in this type of environment.  
         [0020]    In this embodiment, a rotating electrical machine, indicated generally by the reference numeral  12  is provided in an area forwardly of the engine crankcase, indicated by the reference numeral  13 , and is closed by a front cover  14  that is fixed to a front wall of a crankcase  13 . The crankcase  13  provides an anti-friction bearing  15  for journaling a crankshaft  16  of the engine  11 . The crankshaft  16  is of the split type and is provided with one or more throws on which the big ends of connecting rods  17  are journalled by roller or needle type bearings  18 . The connecting rods  17  are connected at their upper ends to pistons, which reciprocate in cylinder bores  19  of the engine.  
         [0021]    A front wall  21  of the crankcase  13  has a nose portion  22  that forms the carrier for the stator, indicated generally by the reference numeral  23 , of the rotating electrical machine  12 . In this specific embodiment, the rotating electrical machine  12  is a generator but it should be understood by those skilled in the art that it also could be a motor for starting the engine  11 .  
         [0022]    A rotor assembly  24  of the rotating electrical machine  12  has a keyed connection to a nose portion  25  of the crankshaft  16 . This rotor is of an inverted cup shape and carries a number of circumferentially spaced permanent magnets  26  opposite of alternating polarity around its circumference. These magnets  26  cooperate with coil windings  27  formed on pole cores or teeth  28  of the stator  23 .  
         [0023]    A cooling fan  29  draws cooling air through an inlet opening  31  for cooling the generator  12 .  
         [0024]    Referring now additionally to FIGS. 2 and 3, as noted the rotor  24  is fixed for rotation with the crankshaft  16 . To this end the rotor  24  has a boss portion, which comprises a boss section  32  fixed to a crankshaft  16  of the engine  11 . The permanent magnets  26  are fixed to a cup shaped member  33  fixed to a flange of the boss section  32  by rivet fasteners  34 .  
         [0025]    The permanent magnets  26  are magnetized such that they have 2n polarities alternating in the circumferential direction. In this example n=8, and the number M of magnetic poles is 2n=16. Regarding the number of magnetic poles arranged in the direction of rotation of the rotor, since North (N) poles and South (S) poles of the same number are disposed at regular intervals in the circumferential direction, the number of magnetic poles is 2n. The number P of teeth or cores (magnetic pole teeth)  28  of the stator core is 3m for a three-phase generator, where n, m are positive The stator  23  is made of laminated thin steel plates as will be described in more detail later by reference to FIGS. 5 and 6. The stator and its individual plates are comprised of continuous cylindrical portions  35  from which the pole cores or teeth  28  extend outwardly in a radial direction and on which the coils  27  are wound. The stator  23  has eighteen teeth  28 , and thus 3×m=18, which gives m=6.  
         [0026]    The coils  27  have U-, V- and W-phases. The coils  27 (U),  27 (V),  27 (W) of each phase are wound on adjacent three teeth in series as seen in FIGS. 2 and 3. Coils  27   a ,  27   b ,  27   c  on adjacent three teeth are connected by a crossover wire  36  to coils  27   d ,  27   e ,  27   f  on adjacent three teeth at a symmetrical position six teeth ahead. Of course the coils  27  and their crossover wires  36  are preferably formed from a continuous strand of wire although they are referred to separately.  
         [0027]    The winding direction of each coil  27   a - 27   f  is made so that induced voltage of each coil  27   a - 27   f  has the same polarity corresponding to polarity change of the permanent magnets  26  to which each coil  27   a - 27   f  faces.  
         [0028]    In this embodiment, the number of teeth or cores  28  of the stator  23  is 3m, that of magnetic poles of the rotor  24  is 2n, and the numbers 3m, 2n are set such that 2/n is not to be an integer so that induced voltages of a plurality of teeth forming a voltage of the same phase have the same polarity and different phases. As a result, driving torque is decreased, enabling size reduction of the driving engine, and a smooth output waveform is effected, improving efficiency of power generation, as is disclosed in Laid Open Japanese Patent Application Hei 11-288449 filed by the present applicant (corresponding U.S. Ser. No. 09/628,755, filed Jul. 31, 2001), and the description thereof will be repeated here.  
         [0029]    In this embodiment, neodymium-iron-boron permanent magnets  26  are used, having 2n=sixteen poles, and the number of teeth  28  is eighteen, that is, 3m=18.  
         [0030]    Therefore, n=8 and m=6. In this case, an angle (pitch) θ1 between the magnets  26  is θ1=π/2n (radian)=22.5°, and an angle (pitch angle) θ2 of the teeth  28  is θ2=2π/3n (radian)=20°.  
         [0031]    Since the number of teeth  28  is a multiple of two, the coils  27  of the same phase (U-phase in FIG. 2) are divided into two groups, that is, symmetrical groups  27   a - 27   c  and  27   d - 27   f  of m/2=three poles each, and each coil group is wound on adjacent three teeth  28  in series. Since the adjacent teeth  28  face to magnets  26  of different polarities, the coils are wound on the teeth alternately in the opposite directions so that induced voltages of the coils are not reversed to each other. In this embodiment, an angle by which 2/m=three teeth  28  are offset from three magnets  26 , or a phase difference θ, is Δθ×(m/2−1)=Δθ×2, and thus Θ=Δθ×2&lt;θ½.  
         [0032]    As has been previously noted, the core of the stator  23  is made up of laminated steel plates. That construction will now be described by principle reference to FIGS. 5 and 6. The laminated thin steel plates of the stator  23  are indicated generally by the reference numeral  37 . Each plate  37  has a continuous cylindrical section  35  from which the poles or teeth  28  radiate. These plates  37  comprise inner thin plates  37   b sandwiched by axial outermost upper and lower two plates  37 a. Except as hereinafter noted, the plates  37   b  and  37   a  are of the same shape. The tip ends of the teeth  28  are stamped out in the shape of a letter T.  
         [0033]    The outermost two thin plates  37   a  have tabs  38  bent at their tip ends at right angles (in the direction of lamination), as shown in FIG. 6, so that the tabs  38  overlie the T-shaped tip portions of the tip ends of the teeth  28  of the middle plates  37   b .  
         [0034]    Near the bottoms of slots between the teeth  28  of the outer plates  37   a  are formed further tabs  39  extending axially outwardly in the direction of lamination. The thin plates  37   a ,  37 b are laminated and fastened together with their pole teeth  28  aligned by a plurality of rivets  41  (FIGS. 3, 4 and  6 ). In addition the attached assembly on the stator  23  is affixed to the crankcase nose portion  22  by a mounting plate  42  (FIG.1) by fasteners  43  that pass through openings  44  in the stator  23 .  
         [0035]    After the plates  37   a ,  37   b  are laminated and fastened together with the rivets  41 , this assembly is coated with insulating material, at least in the region including the teeth  28  and the tabs  39 , that is, the area other than the cylindrical portion  35  of the stator  23 .  
         [0036]    The coil wire is wound around over the insulating material, as shown in FIG. 3. In this case, a crossover wire  36  ( 36 (U),  36 (V),  36 (W)) of each phase is set on the outside circumferential side of the tabs  39  of the outermost thin plate  37   a , as shown in FIG. 4.  
         [0037]    As a result, for the U-phase, circumferentially adjacent three coils shown by symbols Al, A 2 , A 3  and three coils at a diagonal position shown by symbols A 4 , AS, A 6  are formed. Likewise, for the V-phase, coils B 1 , B 2 , B 3  and coils B 4 , B 5 , B 6  at a diagonal position, and further for the W-phase, coils C 1 , C 2 , C 3  and coils C 4 , C 5 , C 6  at a diagonal position are formed. In this case, the crossover wire  36  ( 36 (U),  36 (V),  36 (W)) of each phase is wired along the outside circumference of the tabs  39 .  
         [0038]    The stator  23  having coils  27  wound on all teeth  28  is then coated with insulating material. That is, coils wound on the teeth  28 , and crossover wires  36  set outside the tabs  39 , are coated with the insulating material and thus, the crossover wires  36  are adhesively bonded to the tabs  39  by the insulating material thus restricting their free movement. This final assembly is shown in FIG. 4.  
         [0039]    [0039]FIG. 7 is a front view of a rotating electrical machine constructed in accordance with another embodiment of the invention. This embodiment is made in the same manner as that of FIGS.  1  - 6  and differs only in the number of pole teeth and permanent magnets thus a complete description of the structure is not required.  
         [0040]    In this embodiment the number M of magnetic poles of a rotor  24 A is twelve and the number P of teeth of a stator  23 A is eighteen. Coils  27 A of each of U-, V- and W-phases are wound on every four teeth A in series. In this case, every four teeth  28  on which coils  27 A of the same phase are wound, will face to magnetic poles  26  of the same polarity at the same electrical angle. Also, crossover wires  36 A connecting every four coils of the same phase are set on the outside circumferential side of the tabs (not shown) provided on the outermost layer of the stator. As a result, the crossover wires  36 A are prevented from being moved radially inwardly of the tabs. In addition, the coils  27 A and crossover wires  36 A are coated with insulating material for fixing, restricting free movement of the crossover wires  36 A.  
         [0041]    Thus, from the foregoing description it should be readily apparent that the described embodiments of the invention provide a very simple arrangement for a rotating electrical machine wherein manual labor is substantially reduced in assembly and wherein the crossover wires are automatically and permanently bonded so as to avoid their being positioned where they can obstruct the remainder of the machine or other components which may be associated with it. In addition, this provides a very neat assembly and insures long life without trouble. Of course, the embodiments described are only preferred embodiments of the invention and various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.