Armature of electric motor

An object of the invention is to provide an armature of an electric motor that provides a maximum of space for winding without causing an increase of the magnetic resistance and reduction of the coil space factor. The armature of the electric motor includes a stator yoke 5 of a stator core 1 wherein a plurality of the stator cores 1 forms a substantially annular shape; and a film insulator 4 formed corresponding to a tooth 6 and a stator yoke 5 of the tooth 6, shoes 2b and 3b being provided at locations corresponding to both side ends of a front portion of a protrusion 6a of the tooth 6, the film insulator 4 being fittingly fixed to grooves 2c and 3c by its being sandwiched between a connection-side insulator 2 and an opposite-side-of-connection insulator 3, the insulators 2 and 3 having grooves 2c and 3c at roots of the shoes 2b and 3b, respectively, along both side ends 6b of the front portion of the tooth 6.

TECHNICAL FIELD

The present invention relates to an armature of an electric motor.

BACKGROUND ART

In an armature of a conventional electric motor, a coil-mounting tooth of a stator core has stepped surfaces at locations where a predetermined length portion of the tooth is narrowed from both its end surfaces in the axial direction of the stator core, whereby an insulator is fittingly fixed and a winding space is maximally provided (refer to Patent Document 1 and Patent Document 2, for example).

In another example, an insulator is fixed to both ends of a stator core without having a narrowed tooth as in the above description. A film insulator is disposed to provide insulation within a slot, and a folded portion of the insulator, where the insulator partially protrudes toward the inside of the slot, is provided to control the film insulator in the axial direction (refer to Patent Document 3, for example).

RELATED ART DOCUMENT

Patent Document

SUMMARY OF THE INVENTION

Problems that the Invention is to Solve

In the armatures of the conventional electric motors, however, a problem is that the tooth, which has the portion narrowed by providing the stepped surfaces in order to fittingly fix the insulator to the tooth, causes an increase in magnetic resistance that accompanies the reduced cross section of the tooth. Another problem is that a protrusion toward the inside of the insulator slot, for controlling an insulation material in the axial direction reduces the coil winding space, thus causing reduction of the coil space factor.

The present invention is directed to overcome the above described problems, and an object of the invention is to provide an armature of an electric motor that provides a maximum space for winding without causing an increase of the magnetic resistance and reduction of the coil space factor.

Means for Solving the Problem

An armature of an electric motor according to the present invention comprises a stator core including a stator yoke wherein a plurality thereof forms a substantially annular shape, and a tooth that protrudes inwardly from a middle portion of the stator yoke toward a center axis of the stator yoke; an insulator formed corresponding to the yoke and the tooth of the stator core, the insulator having projections provided at locations corresponding to both side ends of a front portion of a protrusion of the tooth, and also having, at roots of the projections, side end grooves located along both side ends of the front portion of the tooth protrusion; and an insulation film that covers an inner wall of the stator yoke and a side wall of the tooth, the insulation film being fittingly fixed to the groove by a pair of the insulators sandwiching both ends in an axial direction of the stator core.

Advantageous Effects of the Invention

According to the present invention, an insulation film is retained in a position where the space factor of a coil in the neighborhood of the front portion of a tooth protrusion is not influenced, thereby providing adequate electric insulation without causing an increase of the magnetic resistance and reduction of the coil space factor.

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION

Various embodiments of an electric motor armature according to the present invention will be described below with reference to the figures.

FIG. 1is a perspective view of an armature100of an electric motor according to Embodiment 1 of the present invention;FIG. 2is a top view thereof;FIG. 3is a perspective cross-sectional view taken along dotted lines A-A inFIG. 1; andFIG. 4is a plan view showing a cross-section taken along dotted lines B-B inFIG. 1. Winding is not shown in the figures.

The armature100is constituted with a stator core1, an insulator on the connection side,2, and an insulator on the opposite side of connection,3, serving as insulators that sandwich both ends of the stator core1therebetween, a film insulator4serving as an insulation film provided on a side wall of a portion where winding is mounted on the stator core1.

The stator core1is made up of a stator yoke5and a tooth6, a plurality of which is coupled to form a substantially annular shape; the tooth6is protruded from the middle portion of the stator yoke5, inwardly toward the center of the annular shape. A tooth front shoe6bis provided at both ends of a protrusion6a. The stator core1is laminated with T-shaped magnetic steel plates.

Corresponding to the stator core1, the connection-side insulator2is made up of a protrusion of a tooth2aand a stator yoke2d, and a tooth front shoe2bis provided at both ends of a protrusion of the tooth2a.

The tooth front shoe2bprojects more than the tooth front shoe6bof the stator core1, and a groove2cis provided as a side end groove, along both sides of the tooth front shoe6bof the stator core1, at a root of the projection.

Likewise, corresponding to the stator core1, the opposite-side-of-connection insulator3is made up of a protrusion of a tooth3aand a stator yoke3d, and a tooth front shoe3bis provided at both ends of a protrusion of the tooth3a.

Likewise, the tooth front shoe3bprotrudes more than the tooth front shoe6bof the stator core1, and grooves3care provided along the both side ends of the tooth front shoe6bof the stator core1, at the root of the protrusion.

The film insulator4which covers an inner wall of the stator yoke5and a wall on the tooth side is held by the fact that both ends in an axial direction of the end portions of the film insulator4are sandwiched between and fitted into the grooves2cand3c.

The grooves2cand3c, which hold both ends in the axial direction of the end portions of the film insulator4, are provided in positions where the coil space factor is not affected and the respective tooth front shoes2band3badjacently face to each other.

In Embodiment 1, as described above, the grooves2cand3c, which hold both ends in the axial direction of the end portions of the film insulator4, are provided at respective locations where the tooth front shoes2band3badjacently face to each other. Consequently, the fact that the projection of insulator enters within a slot enables coils to be uniformly wound without reducing a winding space of the coil and causing a shift in position of the end of the film insulator in the circumferential direction relative to the stator core.

Further, forming the insulator according to the invention this way enables maximum effective use of the winding space, and thereby the improved coil space factor can lead to an electric motor with high efficiency.

As with the plan view (FIG. 2) showing a cross section taken along dotted lines B-B in the perspective view (FIG. 1) of the armature100,FIG. 5is a plan view showing a cross section at the same position (a position taken along dotted lines B-B) of an armature101of an electric motor according to Embodiment 2. Referring toFIG. 5, a bend portion7eis provided to a groove7cof an insulator on the connection side, 7.

Likewise, albeit not shown, a bend portion8eis provided to a groove8of an insulator on the opposite side of connection, 8. As the configuration with other parts is the same as that in Embodiment 1, the corresponding parts are labeled with the same reference numerals, and their descriptions are not provided herein.

As described above, in Embodiment 2, since the bend portions7eand8eare provided to the grooves7cand8c, respectively, an advantageous effect is that not only does the film insulator fitted into the groove be prevented from shifting in the circumferential direction relative to the stator core, but also the bend portions, acting as constraints, prevent the film insulator from shifting in a radial direction relative to the stator core. This can serve to stabilize the displacement of the film insulator likely to occur while winding the coil, and avoid a winding failure.

FIG. 6is a perspective view of an armature102of an electric motor according to Embodiment 3 of the present invention;FIG. 7is a top view thereof; andFIG. 8is a top view showing a cross section taken along dotted lines B-B inFIG. 6.

In Embodiment 3, when a regular winding by longitudinal cross winding—in which a coil winding transitions from lower layer to upper layer on the side surface of the tooth—is used as a coil winding method, a groove9g, serving as a root groove, is provided also in a dummy coil9fprovided for the purpose of the regular coil winding, and the film insulator4is fitted into the groove9g.

As the configuration with other elements is the same as that in Embodiment 1, the corresponding elements are labeled with the same reference numerals, and their descriptions are not provided herein.

In Embodiment 3, as described above, the groove9gis provided in the dummy coil9f, and the film insulator4is retained at maximum at three places per tooth including grooves9cand3cprovided at two places in the neighborhood of the respective tooth front shoe, thus improving the stability of retaining the film insulator.

The groove9g, provided in the dummy coil9f, serves to retain the film insulator4using only a tooth9aof an insulator on the connection side,9, and the side of a stator yoke9d; however, the invention is not limited to this method.

For example, as shown inFIG. 9, a dummy coil10f, provided to an insulator10on the connection side, may be extended downward from the end of the stator core1. In this case, a groove10gcan be of double supporting structure such that the film insulator is supported by an extended portion of the dummy coil10f, and by not only the tooth10aof the connection-side insulator10and the side of the stator yoke10d, but also the tooth6of the stator core1and the side of the stator yoke5.

This achieves an advantage effect in improving rigidity of the grooved dummy coil, thickness of which extended portion becomes smaller.

FIG. 10is a perspective view of an armature104of an electric motor according to Embodiment 4.FIG. 11is a top view thereof. As with the plan view (FIG. 2) showing a cross section taken along dotted lines B-B in the perspective view (FIG. 1) of the armature100,FIG. 12is a plan view showing a cross section at the same position (a position taken along dotted lines B-B) of the armature104inFIG. 10.FIG. 13is an exploded perspective view of one segment thereof.

In Embodiment 4, the film insulator, fitted into the groove, is extended over a front surface of the tooth, and a film insulator11is extended continuously between adjacent slots. As the configuration with other elements is the same as that in Embodiment 3, the corresponding elements are labeled with the same reference numerals, and their descriptions are not provided herein.

In Embodiment 4, as described above, the film insulator11, which passes over the front surface of the tooth, are extended continuously. Consequently, the film insulator, made up of a single sheet, provides electric insulation of the stator core having a plurality of teeth.

Further, because the film insulator extends over the front surface of the tooth while winding the coil, an advantageous effect is that the insulation failure is reduced such that the film insulator is peeled off from the front surface in the neighborhood of the tooth front shoe or is caught in the coil during coil winding.

This enables reduction of poor quality of the coil winding, and also reduction of the investment cost of manufacturing facilities because of no jig being needed for pressing the film insulator during winding of the coil.

After the stator core1has been electrically insulated and the coil has been wound, the film insulator11may remove its portion extending over the front surface of the protrusion6aof the tooth6, as shown inFIG. 14. This removal can avoid a quality problem with respect to interference of the film insulator with the rotator core.

Further, after the coil has been wound, a film insulator12, which extends over the front surface of the protrusion6aof the tooth6, may be partially cut away, and, as shown inFIG. 15, the film insulators may be extended to enter into spaces between the coils wound on the adjacent teeth. The film insulator, if cut away in its middle portion, may enter into spaces between coils wound on both adjacent teeth.

In this case, the film insulator, which enters into spaces between the winding coils mounted on the adjacent teeth, can act as an inter-phase insulation. This can prevent a short circuit between winding coils of the adjacent teeth, or reduce in a post process a step of inserting another film insulator between the winding coils.

In the present embodiment, as described above, the armature is used having no stepped shape at both end surfaces in the axial direction of the tooth6of the stator core1; however, the invention is not limited to this construction.

As shown inFIG. 16, fittingly fixed together are a tooth16aof the stator core1—whose both end surfaces in a axial direction are formed into stepped surfaces where a predetermined length of the tooth16ais narrowed—and teeth14aand15aof an insulator14on the connection side, and an insulator15on the opposite side of connection, respectively. Even if the foregoing construction is used in doing this, an advantageous effect is obtained in that the coil space factor is improved.

Further, in any one of the forgoing embodiments, in the fabrication step which is not included in the winding step, a film insulator, serving as an inter-phase insulation film is inserted into a space between the winding coils of the adjacent teeth, and, whereby the advantageous effect is increased in that the winding short circuit is prevented.

REFERENCE NUMERALS