Rotary electric machine having shifted winding wire

A rotary electric machine includes a stator in which a plurality of armatures each have a coil formed by a winding wire wound in plural layers around bobbins mounted to a magnetic pole tooth, which are disposed annularly on an inner circumference of a cylindrical frame. The coil is formed by the winding wire being wound with a constant feed pitch in parallel with slots of the bobbins in plural layers. The winding wire forming a first layer of the coil is shifted by half the feed pitch between a left side and a right side of a center axis of the coil as viewed from a plane perpendicular to a stacking direction of a stacked iron core.

TECHNICAL FIELD

The present invention relates to a rotary electric machine, such as an electric motor, which includes a stator having a plurality of armatures disposed annularly on an inner circumference of a cylindrical frame.

BACKGROUND ART

To date, this type of rotary electric machine has been structured as indicated in Patent Document 1. Namely, in a rotary electric machine having a stator in which a plurality of pole portions each having a coil wound therearound are annularly disposed, the coil is wound around each pole portion so as to form a left-right asymmetric cross-sectional shape on a surface perpendicular to the axis of the stator, in order to form the stator having a high coil space factor by using one kind of coil. That is, winding is performed such that, in one turn of a predetermined layer, one of left and right end portions of a winding is shifted to an adjacent layer, or such that, in one turn of a predetermined layer, left and right end portions of the winding are positioned at different positions, whereby a cross-sectional shape of the coil is formed so as to be left-right asymmetric.

CITATION LIST

Patent Document

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

In such a conventional art, winding is performed so as to fill a gap formed between coils adjacent to each other, and therefore, in some of turns, a feed pitch may become greater than feed pitches in the other turns.

In the example of Patent Document 1, a maximum feed pitch is required to be about 2.5 times greater than a standard feed pitch.

When the feed pitch is increased, a winding rate is reduced due to limitation on an acceleration in a coil center axis direction of a winding machine.

The present invention is made in order to solve the aforementioned problem, and an object of the present invention is to provide a rotary electric machine having a stator in which a feed pitch is maintained small in every turn, interference with an adjacent magnetic pole tooth is prevented, and a coil space factor can be enhanced.

Solution to the Problems

The present invention is directed to a rotary electric machine including a stator in which a plurality of armatures each have a stacked iron core which includes a magnetic pole tooth formed so as to project from a yoke portion and having a rectangular longitudinal cross-section, in which the plurality of armatures each have a coil formed by a winding wire being wound around a bobbin mounted to the magnetic pole tooth, and in which the plurality of armatures are disposed annularly on an inner circumference of a cylindrical frame, and, in the rotary electric machine, the coil is formed by the winding wire being wound with a constant feed pitch P in parallel with a slot of the bobbin in plural layers, and the winding wire forming a first layer of the coil is shifted, by P/2 which is half the feed pitch between a left side of and a right side of a center axis of the coil as viewed from a plane perpendicular to a stacking direction of the stacked iron core.

Effect of the Invention

By the rotary electric machine according to the present invention, a stator can be obtained in which a feed pitch can be maintained small in every turn, interference with an adjacent magnetic pole tooth can be prevented, and a coil space factor can be enhanced. Thus, an advantageous effect which cannot be obtained in conventional arts can be obtained.

DESCRIPTION OF EMBODIMENTS

FIG. 1is a top view of a stator of an electric motor according to embodiment 1 of the present invention.

InFIG. 1, a stator1includes a cylindrical metal frame2, and a plurality of armatures3that are annularly arranged on an inner circumference of the frame.

Each armature3includes a yoke portion5, a stacked iron core4having a magnetic pole tooth6that projects from the yoke portion5, bobbins7,8, insulating paper sheets9, and a coil10.

A cross section, of the magnetic pole tooth6, which is a longitudinal cross-section and parallel to the yoke portion5, is rectangular.

FIG. 2is a perspective view of the armature3which does not have the coil10wound therearound.FIG. 3is an exploded perspective view of the stacked iron core4, the bobbins7,8, and the insulating paper sheets9of the armature3.

The armature3is assembled, as shown inFIG. 3, such that the bobbins7,8are mounted to both ends, in the longitudinal direction, of the magnetic pole tooth6from a stacking direction of the stacked iron core4, and thereafter, the insulating paper sheets9are interposed between the bobbins7,8and the stacked iron core4, to wind, from thereabove, the coil10around the magnetic pole tooth6.

The bobbins7,8are formed of a resin, made of a polyphenylenesulfide, an LCP, or the like, exhibiting a good formability, insulate the stacked iron core4and the coil10from each other, and form a winding frame of the coil10. The bobbins7,8are formed so as to be line-symmetric as shown inFIG. 4, and include: U-shaped coil winding portions7a,8a, respectively; and flanges7b,7c,8b,8cprovided so as to be perpendicular, on end surfaces, on both sides, of the coil winding portions7a,8a. The coils10are wound in a slot7dformed between the flanges7band7cand a slot8dformed between the flanges8band8cas described below

Each insulating paper sheet9is formed of an insulating material such as a meta-aramid fiber or a polyphenylenesulfide, and assuredly insulates the stacked iron core4and the coil10from each other.

The coil10is formed by a winding wire13being wound with a constant feed pitch P in parallel with the slots7d,8dof the bobbins7,8in plural layers, as shown inFIG. 5.

The feed pitch P can be set so as to satisfy d≦p≦2d (where d represents a diameter of the winding wire13), andFIG. 5shows a state where winding is performed with the feed pitch P=d.

The winding pattern represents a structure in which, in the first layer, a coil right side portion10bis shifted from a coil left side portion10a, by P/2, with reference to a center axis10cof the coil10as viewed from a plane perpendicular to the stacking direction of the stacked iron core4.

The first layer is an innermost layer of the coil10, and is a coil that is firstly wound from the yoke portion5side toward the inner circumferential side of the stator1.

Next, a method for winding the coil10will be described. As shown inFIG. 6, the yoke portion5of the stacked iron core4is mounted to a main shaft11of the winding machine.

Thereafter, as shown inFIG. 7, while the main shaft11of the winding machine is being rotated, the winding wire13fed from a nozzle12is wound by means of the magnetic pole tooth6having the bobbins7,8mounted thereto.

Winding is performed such that the winding wire13is firstly introduced in the bobbin7, and is thereafter wound toward the bobbin8in parallel with a long side portion of the magnetic pole tooth6. When the winding wire13is wound around the bobbin8that is a short side portion of the magnetic pole tooth6, the nozzle12is moved in the direction indicated by an arrow A inFIG. 7, to feed the winding wire13by P/2.

Next, winding is performed toward the bobbin7in parallel with the long side portion of the magnetic pole tooth6. When the winding wire13is wound around the bobbin7that is a short side portion of the magnetic pole tooth6, the nozzle12is moved in the direction indicated by the arrow A inFIG. 7, to feed the winding wire13by P/2, thereby performing the first turn of winding (FIG. 8).

Thereafter, the second turn and the third turn of the winding are similarly performed, and the winding up to the end of the magnetic pole tooth6is performed, to form the first layer (FIG. 9).

When the winding is thus performed, the coil right side portion10bcan be shifted from the coil left side portion10aby P/2 in the first layer with reference to the center axis10cof the coil10as viewed from the plane perpendicular to the stacking direction of the stacked iron core4.

The bobbins7,8include projections7e,8ein portions where the first turn of the coil is wound, in order to stably shift the coil left side portion10aand the coil right side portion10bfrom each other by P/2.

After the first layer has been wound, return in the direction indicated by an arrow B inFIG. 7is performed, to perform winding of the second layer. The windings of the second layer and the subsequent layers are performed according to the wire of the first layer so as to repeat the feeding at coil ends on both side ends such that the wire is staggered.

Thus, by the winding of the first layer being shifted by P/2, the winding pattern can be changed between the coil left side portion10aand the coil right side portion10bwith reference to the center axis10eof the coil10, as shown inFIG. 5.

Further, a distance over which the feeding is performed at the coil ends on both the side ends is almost constant, and is less than or equal to 1.5 times the feed pitch P.

As described above, according to the present invention, the rotary electric machine includes the stator1in which a plurality of the armatures3each have the stacked iron core4which includes the magnetic pole tooth6formed so as to project from the yoke portion5and having a rectangular longitudinal cross-section, in which the plurality of the armatures3each have the coil10formed by the winding wire13being wound around the bobbins7,8mounted to the magnetic pole tooth6in plural layers, and in which the plurality of the armatures3are disposed annularly on the inner circumference of the cylindrical frame2. In the rotary electric machine, the coil10is formed by the winding wire13being wound with the constant feed pitch P in parallel with the slots7d,8dof the bobbins7,8in plural layers, and the winding wire13that forms the first layer of the coil10is shifted, by P/2 that is half the feed pitch P, between the left of and the right of the center axis10cof the coil10as viewed from the plane perpendicular the stacking direction of the stacked iron core4.

In such a structure, as compared to a winding structure in which shift by P/2 is not performed as shown inFIG. 15, a feeding amount can be maintained small, and interference with a coil wound around an adjacent magnetic pole tooth is prevented, and likelihood is obtained with respect to the circumferential direction of the stator, and likelihood is enhanced with respect to winding expansion or a wire diameter of the winding wire can be enhanced to enhance a coil space factor.

Further, the winding of the first layer is shifted by P/2 between the left of and the right of the center axis of the coil, to enable prevention of interference with the coil of the adjacent magnetic pole tooth, and therefore likelihood can be enhanced with respect to the winding expansion or a coil space factor can be enhanced.

Further, the bobbin has the projection that has a size corresponding to about half the feed pitch P, in one of portions, to the left of and to the right of the center axis of the coil, where the first turn of the coil is wound, whereby a gap of half the pitch P/2 can be formed between the first turn of the winding and the flange portion of the bobbin.

Therefore, even when the winding wire of the first turn is pressed by the winding wires of the second turn and/or the subsequent turns, shift by half the pitch P/2 can be maintained.

FIG. 10is a fragmentary cross-sectional view of a winding pattern according to embodiment 2 of the present invention.FIG. 11is a top view of bobbins according to embodiment 2.

In embodiment 2, the coil winding portions7a,8aof the bobbins7,8have grooves7f,8ffor guiding the winding wire13.

The grooves7f,8fare each formed such that the grooves on the right side are shifted, by P/2, from the grooves on the left side with reference to the center axis10cof the coil10.

The bobbins7,8mounted to both ends of the magnetic pole tooth6are formed so as to be line-symmetric (FIG. 11).

Thus, when the bobbins7,8have the grooves7f,8f, the winding wire13can be more stably wound with shift by half the pitch P/2.

Further, when the feed pitch P is greater than or equal to the wire diameter of the winding wire13, a gap from the coil of the adjacent magnetic pole tooth can be further increased, to enhance likelihood with respect to the winding expansion or enhance a coil space factor.

FIG. 12is a schematic cross-sectional view of coil winding portions of the bobbins7,8according to embodiment 3 of the present invention. In the present embodiment, the grooves7f,8fof the bobbins7,8are V-shaped.

When the grooves7f,8fare thus V-shaped, the winding wire13can be stably wound at predetermined positions of the bobbins7,8, thereby performing winding with enhanced stability.

FIG. 13illustrates a winding pattern according to embodiment 4 of the present invention, and illustrates an exemplary structure in which the magnetic pole tooth6has, on the side surfaces in the longitudinal direction, a tapered portion6athat is wider toward the yoke portion5.

Thus, when winding on the magnetic pole tooth6having the tapered portion6ais performed, the winding wire13of one turn and the wining wire13of the turn immediately following or preceding the one turn geometrically interfere with each other. Therefore, the winding wire13needs to be wound with a space in order to stably perform the winding.

Therefore, the feed pitch P becomes greater than a wire diameter of the winding wire13.FIG. 13illustrates an arrangement that satisfies P=d·√3 (d represents the diameter of the winding wire13). In this case, when, for example, the wire diameter d of the winding wire13is 2.5 mm, the feed pitch P is 4.33 mm, and a coil space factor is increased to 45.9% although a coil space factor is 38.9% in conventional arts.

Further, in this case, each of the bobbins7,8has a shape corresponding to the tapered portion6aof the magnetic pole tooth6, and at least one of bobbins, e.g., the bobbin7has an opening7gthrough which a winding wire is introduced in the flange7bon the yoke portion side as shown inFIG. 14.

The winding wire is introduced through the opening7gof the flange formed in the bobbin7so as not to interfere with the wire of the second layer and/or the subsequent layers.

Also in such a winding, when the coil of the first layer is shifted by P/2 between the left side and the right side as shown inFIG. 14, a gap is formed between the coils adjacent to each other, whereby the same effect as that for embodiment 1 can be obtained.

It is noted that, within the scope of the present invention, the above embodiments may be freely combined with each other, or each of the above embodiments may be modified or abbreviated as appropriate.

DESCRIPTION OF THE REFERENCE CHARACTERS