ROTARY ELECTRIC MACHINE COIL ASSEMBLIES

Abstract: An armature coil assembly for magnet-type rotary electric machines such as alternators or motors, which comprises flat conductor pieces or segments (3) with large-area sides thereof arranged parallel to the direction of the magnetic fluxes of a permanent magnet (8), and a ferromagnetic member (5) inserted between the conductor pieces. The ferromagnetic member inserted provides a magnetic anisotropy in the armature coil along the axis of coil rotation. Thus the flow of magnetic fluxes from the magnet through the armature coil to the machine core (11) is facilitated thereby to reduce leakage magnetic fluxes. A stator coil assembly is also made up by using like coil conductor segments.

Description: The present invention relates to coil assemblies according to the preamble of claim 1 used for rotary electric machines such as magnet generator or magnet motor. A conventional armature coil, as disclosed in the specification of US-A-3091715, comprises tabular half-coil conductors each including an inner portion, outer portion inclined radially and radial central portion provided by printed wiring on both sides of an insulating disc. A radial recess or slot is formed in the central portion of the half coil to divide each conductor into two branches, and a tongue of magnetic material is put to fill the recess thereby to increase the effective magnetic fluxes in the gap. In the above conventional armature coil, when magnetic fluxes pass through the tongue of magnetic material in the axial direction perpendicular to the conductor, an annular eddy current is generated in the conductor on the outer periphery of the magnetic tongue, thereby leading to the disadvantage of the output being reduced by the eddy current loss. Further, since the conductor is tabular in form and occupies a certain width in peripheral direction when arranged on the insulated disc, it is impossible to increase a number of winding turns, and therefore an output more than a predetermined level cannot be produced. A coil assembly according to the preamble of claim 1 is known from the US-A-3 237 036. This known conductor coil is wound in a wave winding. Magnetic conductors are interposed between the electric conductors in the rotor. The individual conductors are mutually insulated for electrical and mechanical stresses by means of synthetic resin or lacquered filler materials. The inserted ferromagnetic conductors provide a magnetic anisotropy in the armature coil in the direction of the magnetic flux to be interlinked, so that the leakage magnetic fluxes are reduced. The known armature coil assembly, however, is not yet optimal with view to high output. It is the object of the invention to improve an armature coil assembly according to the preamble of claim 1 in such manner that it is characterized by a high output. According to the invention, this object is achieved by the features stated in the characterizing portion of claim 1. The parallel electrical connection of each coil conductor with a ferromagnetic member reduces the whole resistivity with the result that more current flows than in the case of the construction according to the US-A-3 237 036. The current flowing in the coil is thus increased thereby to improve the output. In this way the ferromagnetic members are used effectively as magnetic conductors on the one hand, and as a current path on the other hand. In the armature coil assembly according to the invention, on the other hand, the coil conductors have a relatively small width perpendicularly to the magnetic flux, the ferromagnetic members between the coil conductors have a high resistivity and also a small width perpendicularly to the magnetic flux. The result is that the eddy currents are extremely small and much smaller than in the assembly according to the US-A-3 091 715, despite the electrical contact beteen the individual ferromagnetic member and the associated coil conductor. A brief description of the drawings follows, Fig. 1 is a half-sectional front view showing a first embodiment of a flat-type rotary electric machine with an armature coil assembly, according to the present invention. Figs. 2 to 4 are schematic diagrams showing an armature conductor of the machine according to Fig. 1. Figs. 5 to 7 are schematic diagrams showing an AC generator for vehicles and a stator thereof according to a second embodiment of the present invention. Fig. 8 shows a coil conductor segment used for a stator coil assembly of the second embodiment. DESCRIPTION OF THE PREFERRED EMBODIMENTS In a first embodiment shown in Figs. 1 to 4, a three-phase AC coil 1 of a magnet generator includes coil segment or pieces 3 making up conductors radially extending along the diameter on the front and back side of an annular heat conductive insulating plate 2 having a hollow portions at the central part thereof. Fig. 2 illustrates a perspective view of a coil piece 3, and Fig. 3 a front view of the coil piece 3. This coil piece 3 is formed of a single non-magnetic copper plate subjected to press work, in which an upper arm 3a and a lower arm 3b are formed branching out from the center to define a V shape. A predetermined gap is formed in the pressing work so as to accomodate the insulating plate 2 between the upper arm 3a and the lower arm 3b. A couple of iron plates 30 having a substantially equal thickness along the periphery and axis are welded or otherwise connected in the parallel peripheral direction at the parts of the upper arm 3a and the lower arm 3b which are opposed to the magnet 18. As shown in Fig. 3, the opening angle ϑ of the upper arm 3a and the lower arm 3b connected with the iron plates 30 is set in accordance with the number of poles of the magnet 18. Specifically, if the number of poles are six (the number of N and S poles of the magnet 18 is 12 along the periphery), it is set to ϑ = 360/12 = 30 degrees. Further, the parts of the upper arm 3a and the lower arm 3b opposing to the magnet 18 are smaller in axial thickness than the ends thereby to reduce the resistance thereat. The center of the coil piece 3 is inserted from the central hole 2a side of the insulating plate 2, and the insulating plate 2 is inserted between the upper arm 3a and the lower arm 3b. In the process, the upper arm 3a of another coil piece 3 is disposed on the lower arm 3b of the first-inserted coil piece 3 by way of the insulating plate 2. The peripheral end portions 3a' and 3b' of the upper arm 3a and the lower arm 3b of the coil piece are welded to different coil pieces 3 respectively at the outer periphery of the insulating plate 2 thereby to wind the coil pieces 3 in wave form. As shown in Fig. 4, resin 31 or the like is inserted securely in the gap between different upper arms 3a. Holders 7 and 8 with a channel or U-shaped section are arranged through a heat conductive insulating sheet 6 on the outer and inner peripheral sides of the three-phase AC coil 1. These holders 7 and 8 are made of a material of high heat conductivity such as aluminum, and insulates a rear housing 9 and the coil pieces of the three-phase AC coil 1 from each other by means of the heat conductive insulating sheet 6. The rear housing 9 formed of aluminum, on the other hand, includes a flat portion 9a covering the end face of the three-phase coil 1, a first holder section 9b defining the outer periphery of the holder 7 formed on the outer periphery of the flat portion 9a, and a second holder section 9c formed on the inner side of the flat portion 9a for defining the outer periphery of the holder 8. The three-phase AC coil 1 having the holders 7 and 8 mounted thereon is fixed between the first holder section 9b and the second holder section 9c. The inner side of the second holder section 9c is formed with a recess 9d into which a shaft 13 is inserted with a bearing 16 therebetween. Further, the outer periphery of the flat portion 9a is formed with a fin 9e to secure heat radiation. A flat iron core 11 of magnetic material such as a ferromagnetic iron is arranged with a heat conductive insulating plate 10 between the three-phase AC coil 1 and the flat portion 9a of the rear housing 9. The front housing 12 is also formed of aluminum, and the three-phase AC coil 1 is securely held between the front housing 12 and the rear housing 9. Two openings including first and second openings 12a and 12b are formed in the axial ends of the front housing 12, and a plurality of exhaust holes 12c are formed on the outer periphery along the diametrical direction. Also, a partition wall 12d is provided between the first and second openings 12a and 12b. The step 12e of the front housing 12 is connected by spigot joint with the first holder section 9b of the rear housing 9, so that the housing 9 and the housing 12 are integrally fixed by a through bolt not shown. A screw 19 is used to secure a bearing 16 with a bracket 20 fixed on the inner side of the front housing 12. A shaft 13 having a pulley 14 fixed to an end thereof with a bolt 15 is rotatably supported on the front housing 12 and the rear housing 9 through the bearings 16. The outer periphery of this shaft 13 has a rotor 17 fixed thereto, which rotor 17 is adapted to rotate integrally with the shaft 13. The rotor 17 is provided with a permanent magnet 18 forming a field at a position opposite to the iron core 11 through the three-phase AC coil 1. This permanent magnet 18 is magnetized in axial direction. A plurality of such permanent magnet 18 have magnetic poles alternating in polarity and arranged along the circumferential direction. The permanent magnet 18 may alternatively be magnetized in the circumferential direction instead of the axial direction. The permanent magnet 18 may be replaced with equal effect by iron core wound with a coil to generate a magnetic a field. In addition, a permanent magnet may be used in place of the iron core 11 making up a magnetic member. A plurality of coil pieces 3 are arranged over the peripheral width of the permanent magnet 18. A plurality of scoops 17a and fans 17b are formed at positions opposing to the first and second openings 12a and 12b respectively along the periphery on the front housing 12 side of the rotor 17. A hole 17c is provided at the positions of the scoops 17a. A thyristor 21 is electrically connected to the three-phase AC coil 1 and is securely fitted by screw to the inner periphery of the front housing 12. An output terminal 22 is electrically connected to a thyristor bridge including the thyristor 21 and a diode not shown. With the rotation of the pulley 14, the rotor 17 rotates with the shaft 13. The rotation of the fans 17b of the rotor 17 causes the air from the first opening 12a to cool the thyristor bridge 21 and to flow out through the exhaust ports 12c. On the other hand, the scoops 17a causes the air from the second opening 12b to cool the three-phase AC coil 1 through the hole 17c and flow out through the exhaust ports 12c in similar manner. With the rotation of the magnet 18, an AC power is generated in the three-phase AC coil 1, which power is rectified by the thyristor bridge into a predetermined voltage. This voltage is supplied to an external electrical load through the output terminal 22. Since the iron plate 30 is connected to the parts of the upper arm 3a and the lower arm 3b opposing to the magnet 18, the coil piece 3 and plate 30 are connected in parallel to each other. Thus, assuming exemplarily the use of iron and copper of the same sectional areas as the respective conductors, then the iron (9.80 x 10⁻⁸ ohm·m in resistivity) and copper (1.72 x 10⁻⁸ ohm·m in resistivity) are connected in parallel, so that the whole resistivity is reduced to 1.46 x 10⁻⁸ ohm·m, with the result that a more current flows than in the case of construction of using copper alone. The current flowing in the coil piece 3 is thus increased thereby to improve the output even more. In this way, the plate 30 is used to apply the magnetic fluxes of the magnet 18 effectively on the one hand and used as a current path on the other hand. A second embodiment is shown in Figs. 5 to 7, Fig. 5 illustrating a front sectional view of the essential parts of an AC generator for vehicles. The essential parts are configured in the same way as those disclosed in the specifications of the U.S. Patents Nos. 441829 and 4419597. Figs. 6 and 7 show a stator. This stator 50 is mounted on the inner periphery of a front-side frame 40. A couple of pole cores 42 wound with a rotor coil 41 are arranged rotatably on the inner periphery of the stator 50. The stator 50 includes a stator core 51 and a stator coil 52 wound on the stator core 51. The stator coil 52, as shown in Fig. 8, comprises coil conductor segments each having an upper arm 53a and a lower arm 53b branched out from the center of each segment 53 made of a single copper plate. The upper arm 53a and the lower arm 53b are arranged in parallel to each other, to each end surface of which is welded an iron plate 54 of the same length as the axial length of the stator core 51 (the axial length of the rotor coil 41). A cylindrical insulating plate support 55 is inserted between the upper arm 53a and the lower arm 53b, and in the case of three-phase AC a plurality of another upper arms 53a or lower arms 53b are arranged in a multiple of three between the upper arm 53a and the lower arm 53b of one coil segment 53. Also, the ends of different upper arms 53a and lower arms 53b are welded in wave winding outside of the end of the insulating plate support 55, and the three-phase stator coil 52 is formed cylindrically in such a manner as to arrange a multiplicity of coil segment 53 along the peripheral direction. The coil segments 53 of the stator coil 52 are arranged in such a way that the thickness of the coil segments 53 lies along the radial direction. The stator coil 52, on the other hand, is provided with a first resin member 57 in spaced relations from the ends at the central part thereof and a second resin member 56 at the ends thereof to prevent the coil segments 53 from coming into contact with each other. Also, an insulating member is inserted between the stator core 51 and the stator coil 52. Further, a coil segment 53 is exposed between the first resin 57 and the second resin 56, and the exposed portion 52a is disposed at a position opposed to the diametrical periphery of a couple of fans 43 fixed on the ends of the pole core 42. The air from the fans 43 cools the exposed portion 52a acting as fin thereby to cool the whole of the stator coil 52 more effectively. The operation of the above-mentioned AC generator for vehicles will be explained. A current is supplied through a brush 44 and a slip ring 45 to a rotor coil 43 thereby to induce magnetic poles N and S in a lug 42a of the pole core 42. Also, the rotary force of the internal combustion engine is transmitted through a pulley 46 to the pole core 42 from a shaft 47. With the rotation of the pole core 42, an AC current is induced in the stator coil 52. This AC current is rectified by a rectifier, and the output voltage is controlled by a regulator.

Claims: An armature or stator coil assembly comprising flat coil conductors (3; 53) having large flat side surfaces circumferentially arranged parallelly to direction of an incoming magnetic flux to be interlinked, and a ferromagnetic member (30; 54) provided between said flat side surfaces characterized in that the ferromagnetic member (30; 54) is electrically conductive and provided in electrical contact with one of each two circumferentially adjacent flat coil conductors (3; 53). An armature or stator coil assembly according to Claim 1 wherein said ferromagnetic member (30; 54) is disposed substantially in opposed relationship with field poles. An armature or stator coil assembly according to Claim 1 or 2, wherein each of said conductors (3) is made up of a V-shaped conductor segment. An armature or stator coil assembly according to Claim 3, wherein a plurality of iron plates (30) having substantially the same thickness along the peripheral and axial directions are connected in parallel on the sides of said V-shaped segments (3a, 3b). An armature or stator coil assembly according to Claim 4, wherein the opening angle ϑ of said V-shaped segment (3a, 3b) is given as 360/2N (where ϑ is the number of corresponding field poles). An armature or stator coil assembly according to claim 1, comprising a cylindrical insulating support (55), coil pieces (53) arranged along said support (55) each having first and second parallel arms (53a, 53b) branched out a central portion thereof with a respective iron plate (54) and with said support (55) inserted between said arms, first cylindrical insulating resin member (57) centrally filling between said coil pieces (53), and a second insulating resin member (56) fixing both ends of said coil pieces (53). An armature or stator coil assembly according to Claim 9, wherein said second insulating resin member (56) exposes portions of said coil pieces (53) for cooling effect.

Inventors: KANAYAMA, KENJI, KINKORI, SHUZO, SUGI, HIDEKUNI
Applicants: NIPPONDENSO CO., LTD.
Application year: 1986
Main classification: H02K21
IPC codes: H02K3, H02K21, H02K19