ARMATURES AND METHOD FOR MANUFACTURING SUCH ARMATURES

Abstract: An armature for motor use is provided with an improved integrated armature coil body. The integrated armature coil body includes annular and substantially flat surface portions projecting above one end surface of an armature core, the flat surface portions being arranged and disposed approxi­ mately in the Archimedes' spiral relationship with respect to the center of the armture core. The integrated armature coil body includes a plurality of winding portions each of which has first and second straight portions inserted into different slots throughout the axial length of the armature core, and first and second substantially flat portions projecting out of the armature core. Different first and second substantially flat portions of the armature coil body are overlapped one upon another.

Description: TITLE OF THE INVENTION ARtiATURES AND METHOD FOR MANUFACTURING SUCH ARPIATURES FIELD OF THE INVENTION The present invention relates to a rotating electrical machine, more particularly, to an armature and a method for manufacturing the same which is, for instance, used in a motor for starting an internal combustion engine of an automotive vehicle. DESCRIPTION OF THE PRIOR ART In one, of the conventional armatures, or of the conventional manufacturing methods of the same, first, a straight conductive wire having a predetermined length is eccentrically bent at a nearly center position of the wire so that the bent wire is of a pine-needle shape having a bent portion and a first and a second straight portion, the first and second straight portions being extending almost parallel each other but extending away at a small degree angle. Then, a necessary number of such bent wires are inserted into the corresponding number of slots of an apparatus comprising an external rotational cylindrical jig and an internal cylindrical jig for setting the bent wires and for locating them from the prescribed slot positions, where the slots are spaced equally round both the inner circumference of the external rotational cylindrical jig and the outer circumference of the internal cylindrical jig. Therefore, the bent wires are so radially disposed that the bent portions of the wires project above the flat surfaces of the external and internal cylindrical jigs. In this condition, the height of the bent portions of the inserted wires are regulated by a jig of the apparatus in order to prevent the bent wires from moving in the longitudinal direction of the bent wires. After this, an appropriate relative rotational motion is applied between the external and internal jigs to form an integrated coil body. Then, the integrated coil body is pulled out from the jigs and is inserted into slots of an armature to assemble a motor. However, a motor using the above described conventional integrated coil body has a dificiency that by the relative rotational motion, the bent portions are transformed into chevron shape and protrude above one end surface of the armature, thus causing a relatively large-size motor, especially in the axial direction. SUMMARY OF THE INVENTION It is accordingly an object of this invention to provide an armature used in a motor, wherein the armature has necessary minimum height end portions of an integrated coil body projecting above one side of the armature core opposite to the other side on which a commutator is installed. Another object of this invention is to provide a compact and powerful armature which has good characteristics for the effects of the improved air resistance and minimized centrifugal force or moment thereof. A still further object of this invention is to provide a manufacturing method for an armature having the afore-mentioned features. Briefly stated, in order to accomplish the afore-going objects and other objects other than those described above but derived from this invention, An armature of a motor comprising: an armature core having a plurality of annualy arranged bores throughout its axial length; a shaft rotatably disposed in the center of said armature core; a commutator provided at one end portion of said armature core and being fixedly mounted on said shaft; and an integrated coil body including of a plurality of winding portions, each of said winding portions having first and second straight portions extending through the bores of said armature core and being connected to said commutator at one end, and a bent portion therebetween projecting above the other end surface of said armature core, said bent portions of said winding portions forming substantially flat surface portions annualy disposed in the Archimedes' spiral relationship with respect to said the other end surface of said armature core. In addition, in order to accomplish the aforesaid objects, a manufacturing method comprises the steps of: (1) eccentrically bending at a nearly center position of a straight conductive wire having a predetermined length to thereby form a turn back portion and a first and a second straight portion, said first and second straight portions extending away at a certain amount of degree angle; ; (2) inserting said first and second straight portions of necessary number of said eccentrically bent conductive wires into a corresponding number of slots provided both with the external rotational cylindrical jig and the internal cylindrical jig disposed in said external jig for locating them from the stot positions, whereby said conductive wires are radially disposed while the extended turn back portions of the conductive wires caused by the eccentrical bending work being disposed inward with respect to the center of the internal jig; (3) applying pressure to the top portion of said turn back portion of each said conductive wire; (4) regulating the innermost edge portions of said turn back portions by inserting a member therein; ; (5) thereafter, relative rotational motion between the external and internal cylindrical jigs in one direction being applied by a predetermined rotational angle in order to make an integrated coil body, whereby each of the turn back portions of the conductive wires being transformed into a first substantially flat portion and a second substantially flat portion communicated with said first substantially flat portion via a twisted step portion therebetween, said first and second substantially flat portions of different conductive wires being overlapped one upon another, said first and second flat portions being disposed substantially in the Archimedes' spiral relationship, respectively; ; (6) then, transferring said integrated coil body from said external and internal jigs, and inserting said first and second straight portions into a plurality of annualy disposed slots throughout the axial length of an armature core, said first and second straight portions extending out of the armature core being connected to a commutator. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view showing details of a jig to form a coil wire of pine-needle shape according to the invention; Fig. 2 is a front view showing details of an apparatus which forms an integrated armature coil body according to the invention; Fig. 3 is a view, partially in cross-section, of a portion of the apparatus of Fig. 2; Figs, 4(a), 4(b), 4(c) and 4(d) are partial front views explaining stages of formation of the integrated armature coil body; Fig. 5(a) is a front view showing details of the coil wire; Fig. 5(b) is a plan view of Fig. 5(a); Fig. 6 is a plan view similar to that of Fig. 4(d) and illustrates the Archimedes' spiral of the coil wires, Fig. 7 is a front view of an armature core; Fig. 8 is a perspective side view showing details of an armature according to this invention; ; Fig. 9 is a front view of the armature according to this invention; and Fig. 10 is a vertical sectional view of an important part of this invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS An embodiment of this inventions will now be described hereinafter in detail with reference to the accompanying drawings. As shown in Fig. 1, a single straight conductive wire 1 at one end fixed to a jig (not shown) is bent in almost center against a peripheral portion of a bend shaft 2 by rotating a pin 3 in the direction of an arrow (from position 3a to position 3). In this case, the rotational center of the pin 3 does not correspond to the center of the bend shaft 2. Bending the conductive wire in the above prescribed method forms a conductive wire of pine-needle shape having a first straight portion being an outboard wire la, a first bent portion Ib bent at right angle to the outboard wire la, an "un letter shape portion lc extending from the bent portion ib, a second bent portion ld connected to the other end of the 'U " letter shape portion lc and being bent at right angle to the axial direction of the outboard wire la, and a second straight portion being an inboard wire le extending from the bent portion ld. And as shown in Fig. 1, the outboard wire la and the inboard wire le both are opposing each other while extending away at ' an adequate amount of degree angle. An integrated armature coil body forming apparating, as shown in Figs. 2 and 3, comprises a first housing 18 having a hollow portion throughout its axial length, extending through the upper side to the lower side in the embodiment, at the center of the lower side of which is provided a projection 18a extending throughout the hollow portion toward the upper side. The forming apparatus also comprises a second housing 17 one side, the left side in the embodiment, of which is fitted to the first housing 18 and is secured to a base 19 by adequate means as the first housing 18 secured to it. In the hollow portion is rotatably disposed a cylindrical jig 4 for twisting the conductive wire 1 by a predetermined amount of twist, through a bearing means 28, which has a plurality of semi-circular slots, twenty-three slots in the embodiment as shown by Fig. 4(a), spaced equally round the inner circumference. The jig 4 is prevented from moving in the axial direction by a holding fixture 26 secured to the first housing 18 by means of bolts and nuts and the like. For twisting the inboard wires le by a certain amount of twist another cylindrical hollow jig 5 is positioned in the hollow space of the jig 4, which has the corresponding number of semi-circular slots 5a spaced equally round the outer circumference while facing to the semi-circular slots 4a of the jig 4 as shown in Fig. 4(a). The cylindrical hollow jig 5 has an axial bore 8 throughout its axial length and is secured to the projection 18a by means of a screw 27 and the like threadingly engaged through the bore 8 in the jig 5 with the projection 18a. The jig 4 has a gear portion 6(Fig. 2f on its curved surface, which meshes a gear portion 7a of a rack 7 movably supported through a bearing means 7b with the first housing 18 in the both directions as shown by arrows A and B(Fig. 2). Fig. 2 shows that movement of the rack 7 in direction A is to rotate the jig 4 in the counter-clockwise direction (arrow C) and the reverse movement is to rotate it in the clockwise direction (arrow DZ, At both the bottom side of the hollow portion of the first housing 18 and the base 19 are provided a plurality of holes throughout them, twenty-three holes in the embodiment, and which are so radially positioned in accordance with the corresponding number of holes formed by the slots 4a and slots 5a at the faying surfaces of the jig 4 and the jig 5 that there are formed communicating passages therethrough. An extrusion member 13 can be moved in its axial direction, up and down in Fig. 3, under air pressure so that its pin portions move up and down in the communicating passages. A rod 12 is movably disposed in the second housing 17, one end of which is secured to a cylinder 14 so that the rod 12 can move downward (direction E) by applying pressure to the cylinder. The rod 12 has serrated portions 12a to which a gear member 15 is connected in order to rotate the rod 12 in direction either toward the paper or from the paper toward the reader in the drawing. A "L"-letter shape bearing member 16 is provided between the gear member 15 and the top edge portion of the first housing 17 to thereby easily rotate the gear member 15 which is, however, prevented from moving in its axial direction by a flange portion 28a of a gear 28 which forms a gear train together with the gear member 15. To the other end of the rod 12 is secured a supporting arm 11 extending parallel to and toward the upper surface -of the first housing 18. A coil supporting jig 10 is provided on the extending side of the supporting arm 11, and to which a columnar cored bar 9 is secured. In this case, the columnar cored bar 9 is disposed to be in the circular orbit passing the center of the bore 8 while having a similar circular shape as the bore portion 8 does. In operation, when inserting pine-needle shape conductive wires 1 into the holes formed by the slots 4a and 5a at the matching surfaces of the jig 4 and the jig 5, in consideration of the working, the supporting arm 11 is rotated 90 degrees from position shown in Fig. 3 either toward the paper or from the paper toward the reader by the gear train (the gears 15 and 28). As shown by Figs. 4fa), 4(b), 4(c) and 4(d), the outboard wires la of the pine-needle shape conductive wires of Fig. 1 are inserted into the slots 4a of the jig 4 and the inboard wires le of same are inserted into the slots 5a of the jig 5 by a wire inserting device, whereby the "U"-letter shape portion lc of each wire is radially disposed inboard(fig. 4(a)). Then, after the insertion of the wires 1, the supporting arm 11 is reversely rotated the same degrees to position shown in Fig. 3. Thereafter, the jig 4 is rotated by the rack 7 in the clockwise direction (direction D) as viewed in Fig. 2 by an amount of half the distance between the neighboring slots against the jig 5, and the rotation of the jig 4 adjusts the diameter of the space defined by the curved portions lc of the conductive wires 1 of Fig. 1 so that it becomes almost equal to the diameter of the bore 8 of the jig. 5. Pressure is introduced to a chamber of the cylinder 14 and the rod 12 is moved downward (direction E), this causing the insertion of the columnar cored bar 9 into the bore 8. At this time, the innermost curved portions lc of the wires 1, too, are adjacent to or almost in contact with the curved surfaces of the columnar cored bar 9 as shown by Fig. 4(c). In this condition, pressure of 550 to 600kg is constantly supplied to the conduction wires 1 by the coil supporting jig 10 through the cylinder 14, the rod 12 and the supporting arm 11, while regulating by the cored bar 9 the innermost portions of the curved portions lc of the conductive wires 1. Under this pressurized condition the jig 4 is rotated by the rack 7 in the counter-clockwise direction (direction C) as viewed in Fig. 2 by an amount of six and point eight times the distance between the neighboring slots against the jig 5 (Fig. 4(d)). As described above, since the innermost portions of the curved portions lc of the conductive wires 1 are prevented from extending against the curved surfaces of the cored bar 9, the contact portion between them function as fulcrum so that a twisted portion lg is formed as shown in Figs. 5(a) and sex). A first flat portion if and a second flat portion lh are simultaneously formed with pressure applied thereto. The first flat portion if and the second flat portion lh are almost parallel to the top surface of the jigs 4 and 5, however, the first flat portion If is more adjacent, an amount of the diameter of the wire 1, to the surface than the second flat portion lh does as shown by Fig. 5(a). Therefore, it is clear is Fig. 4(d) that the first flat portion if and the second flat portion lh of different conduction wires 1 are overlapped one upon another wherein the first flat portions if and the second flat portions lh are annularly disposed on the same flat surfaces, respectively. Furthermore, a twist is given to each of bent portions li to lj. Finally, the jig 4 is rotated against the jig 5 again in the clockwise direction (direction D) as viewed in Fig. 2 by an amount of 0.3 times the distance between the neighboring slots. This is provided for precluding possible spring back of the conductive wires 1. As the result, the first flat portion lf extending toward the inboard wire le from the outboard wire la and the second flat portion lh extending toward the outboard wire la from the inboard wire le are formed respectively in the Archemedesl spiral relationship. As shown by figs. 6 and 7, the Archimedes' spiral is determined as follows: EMI11.1 wherein, n is number of the slots 21 (Fig. 7) and d is the diameter of the conductive wire 1. In the embodiment, n is 23 (twenty-three slots) so that if e is three hundreds and 360 sixty over twenty three 2e3) r is then calculated as follows: EMI11.2 The calculated result means that the first flat portion If becomes closer to the center of an armature core 20, the amount of¯the diameter of the conductive wire 1, for every three hundred and sixty. over twenty three rotational degrees. Thereafter, the supporting arm 11 is again rotated, by the gear train (15, 283 through the rod 12, 90 degrees from position shown in Fig. 3, as described above, either toward the paper or from the paper toward the reader to facilitate removal of the integrated armature coil body formed in the coil-winding process described above. The extrusion member 13 is then moved upward (in direction F) by air pressure to take out the integrated armature coil body 1 from the apparatus. As shown in Figs. 7, 8 and 9, the outboard wires la and inboard wires le of the integrated armature coil body 1 are inserted into the slots 21 of the armature core 20 which are spaced equally round the circumference of the armature core 20, and which are throughout its axial length. Each slot 21 in the armature core 20 is applied with an insulating paper or insulation member for an insulation purpose at assembly. The armature core 20 has an armature shaft 22 on one end of which a commutator 24 is fixedly mounted. At this time, each of the outboard wires la and each of the inboard wires le extending through different slots 21 to the outside of the armature core 20 are connected each other on each segment of the commutator 24. Even after the insertion of the integrated armature coil body 1, the first and second flat portions If and lh remain in the Archemedes' spiral relationship. As shown in figs. 9 and 10, the height h of a coil end 23 of the embodiment according to this invention can be found to be: h ay 2d + R where d is the diameter of the conduction wire 1 and R is the radius of curvature of the bent portion lj of that wire 1. According to our experimental results from actually manufacturing an armature, using an integrated armature coil body 1 prepared by the above-mentioned method, the height h of the coil end 23 of such armature was 9.5mm. However, the height h of an armature provided with an integrated armature coil body prepared by one of the conventional methods was 16mm, provided that the diameter d of the conductive wire 1 used in the experiments was 2.6mm. As it is clear from the experimental results that according to the present invention the coil ends' height h can be reduced by almost half. According to the invention, the integrated armature coil body 1 of an armature has first and second flat portions If and lh and they are annualy disposed such that first flat portions If and second flat portions ih of different conduction wires of the integrated armature coil body 1 are overlapped one upon another, thus it is possible to minimize the height h of the coil end 23, and manufacture a small and powerful armature with the improved centrifugal force strength. And, according to the invention, the conductive wire I of pine-needle shape has the first and second straight portions la and le, and a first predetermined relative rotational motion on a concentric circle is applied in one direction between its first and second straight portions la and le while applying pressure over the bent portions, thereafter another second predetermined relative rotational motion is applied in the reverse direction, thus it is also possible to manufacture an armature having such integrated armature coil body 1 made by the steps described above. It will be noted that the invention is not limited to the embodiment illustrated and described in the specifications, and various changes or modifications within the gist of the invention can easily be applied by those skilled in the art. For example, an even number of conductive wires more than two may be inserted into one of the slots of the armature core, the height of the coil end portion can be given by: h ss nd + R where n is the number of conduction wires inserted into each slot.

Claims: WHAT WE CLAIM IS: 1. An armature of a motor comprising: an armature core having a plurality of annualy disposed bores throughout its axial length; a shaft rotatably disposed in the center of said armature core; a commutator provided at one end portion of said armature core and being fixedly mounted on said shaft; and an integrated coil body including of a plurality of winding portions, each of said winding portions having first and second straight portions extending through the bores of said armature core and being connected to said commutator at one end, and a bent portion therebetween projecting above the other end surface of said armature core, said bent portions of said winding portions being annualy disposed substantially flat surfaces with respect to said the other end surface of said armature core. 2 An armature of a motor as claimed in claim 1, in which said bent portion includes a first substantially flat portion extending from said first straight portion toward said second straight portion and a second substantially flat portion extending from said second straight portion toward said first substantially straight portion, said first substantially flat portion being communicated with said second substantially flat portion through a twisted step portion therebetween, whereby said first and second substantially flat portions of different winding portions being overlapped one upon another. 3. An armature of a motor as claimed in claim 2, wherein said first and second substantially flat portions are arranged and disposed substantially in the Archimedes' spiral relationship respectively with respect to said shaft. 4. A method for manufacturing an armature of a motor comprising the steps of: (1) eccentrically bending at a nearly center position of a straight conductive wire having a predetermined length to thereby form a turn back portion and a first and a ¯ second straight portion, said first and second straight portions extending away at a certain amount of degree angle; ; (2) inserting said first and second straight portions of necessary number of said eccentrically bent conductive wires into corresponding number of slots provided both with an external rotational cylindrical jig and an internal cylindrical jig disposed in said external jig for locating them from the slot positions, whereby said conductive wires are radially disposed while the turn back portions of the conductive wires caused by the eccentrical bending work being disposed inward with respect to the center of the internal jig; (3) regulating the innermost edge portions of said turn back portions by inserting a member therein; (4) applying pressure to the top portion of said turn back portion of each said conductive wire; ; (5) thereafter, relative rotational motion between the external and internal cylindrical jigs being applied in one direction by a predetermined- rotational angle in order to make an integrated coil body, whereby each of the turn back portions of the conductive wires being transformed into a first substantially flat portion and a second substantially flat portion communicated with said first substantially flat portion via a twisted step portion therebetween, said first and second substantially flat portions of different conductive wires being overlapped one upon another, said first and second flat portions being disposed substantially in the Archimedes' spiral relationship, respectively; ; (6) then, transferring said integrated coil body from said external and internal jigs, and inserting said first and second straight portions into a plurality of annualy disposed slots throughout the axial length of an armature core, said first and second straight portions extending out of the armature core being connected to a commutator. 5. A method as claimed in claim 4, further comprising the step of: relative rotational motion being applied in the. reverse direction by a rotational angle smaller than said predetermined rotational angle to thereby extend the radius of the space defined by the innermost edge portions of said turn back portions before regulating the innermost edge portions of said turn back portions.

Inventors: HAMANO, SATORU, MAEKAWA, TSUTOMU, MORI, MASANORI, OHMI, MASANORI, UZURA, SHOGO
Applicants: NIPPONDENSO CO., LTD.
Application year: 1985
Main classification: H02K15
IPC codes: H02K23, H02K3, H02K15