Abstract:
An electric motor stator has a stator core and a plurality of windings wound around teeth of the stator core. Each of the windings has two tooth winding portions with a crossover wire extending therebetween. Each of the windings starts from a neutral wire and winds around a first tooth to form a first tooth winding portion and then winds around an opposed tooth to form a second tooth winding portion with the crossover wire extending as a power wire. Thus, the second tooth winding portion is started from the power wire. A terminal end of the second tooth winding portion is drawn out and connected to the neutral wire. The stator core has an insulator having support portions for preventing the tooth winding portions from falling outwards. The power wire is held between the tooth winding portion and a slot bottom so as to be fixed.

Description:
TECHNICAL FIELD 
   The present invention relates to electric motor stators. 
   BACKGROUND ART 
   An electric motor has a stator and a rotor which is rotatably placed in the stator. Conventionally, there is an electric motor whose stator has a stator core having a plurality of teeth and windings wound around the teeth of the stator core via insulators. The electric motor of this type is used as a motor for a compressor of an air conditioner and so on. 
   Windings are wound around the teeth. At this time, in order to insulate a crossover wire of each winding, an insulating tube, an insulating sleeve or the like is required. In an attempt to dispense with the insulating tube and so on, there is known a stator having insulators in a stator core that are provided with grooves in which the crossover wires are housed, so that contact of the crossover wires of one phase with the crossover wires of the other phases is prevented (e.g., see JP 2002-101596 A). 
   However, in a 6-slot concentrated winding stator, since the same phases are positioned 180 degrees opposite to each other, the length of a winding that runs without being wound increases, causing deterioration of winding workability at the time of wire connection. Moreover, a power wire of a winding of one phase is likely to be brought into contact with tooth winding portions of other phases. 
   SUMMARY OF THE INVENTION 
   The present invention was made in order to solve the above conventional drawback, and an object of the present invention is to provide an electric motor stator that can prevent a power wire of a winding of one phase from being brought into contact with windings of other phases so as to have high quality and that offers superior assembling workability. 
   An electric motor stator, according to the present invention, comprises a stator core having a plurality of teeth and slots, each slot being formed between circumferentially adjacent teeth; and windings, a part of each winding being wound around teeth of the stator core. And, each winding includes tooth winding portions, a neutral wire, a crossover wire, and a power wire. The winding is wound around one of two opposed teeth, starting at an end of one tooth winding portion that follows the neutral wire, and the crossover wire directed from another end of the tooth winding portion around the one tooth toward the other of the opposed teeth connects to the power wire, and at an end of a tooth winding portion to be around the other tooth that continues from the power wire the winding is wound around the other tooth, and another end of the tooth winding portion around the other tooth is connected to the neutral wire. The electric motor stator further comprises an insulator having support portions that are placed at a bottom of the respective slots to prevent the tooth winding portions from falling radially outwards, and the power wire is held between the tooth winding portion and the insulator so as to be fixed. 
   In the electric motor stator with the above construction, since the power wire serving as a crossover wire between the opposed teeth is held between the tooth winding portion and the insulator so as to be fixed, it is possible to perform wiring without wobbling of the power wire. Moreover, a complicated arrangement for fixing the power wire is not required. Furthermore, the support portion of the insulator can prevent the winding from falling outwards, which enables the wiring to be wound in a stable state, and also this stable winding state can be maintained. 
   In one embodiment, the insulator is provided with a wiring separator to keep the power wire and the neutral wire spaced from each other by a predetermined distance. 
   In the above embodiment, because the insulator is provided with the wiring separator for keeping the predetermined distance between the power wire and the neutral wire, it is possible to prevent the power wire from being brought into contact with the neutral wire. Moreover, wiring can be surely performed such that the power wire is not brought into contact with the neutral wire in the winding operation. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of an electric motor stator according to the present invention; 
       FIG. 2  is a plan view of an insulator of the stator; 
       FIG. 3  is a side view of the insulators of the stator in a developed state; 
       FIG. 4  is a circuit diagram showing a state of connection of windings of the stator; and 
       FIG. 5  is a simplified diagram for showing a winding method for the stator. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Next, a specific embodiment of an electric motor stator according to the present invention will be described below with reference to the drawings.  FIG. 1  is a simplified view of essential parts of a motor in which the stator is used. The motor is constituted mainly of the stator  1  and a rotor  2  which is rotatably fitted in the stator  1 . The stator  1  has a stator core  3  and windings  4  wound on the stator core  3 . The stator core  3  has a core main body  6  formed by stacking a large number of annular-shaped thin plates made of electromagnetic steel and insulators (insulating members)  5 ,  5  provided on axial end surfaces of the core main body  6  (see  FIGS. 1 to 3 ). The stator core  3  is provided with a plurality of teeth T (six in this case) at a predetermined pitch along a circumferential direction thereof. The windings  4  are wound on the respective teeth T. At this time, slots  15  are formed between adjacent teeth T along the circumferential direction. There are six slots  15  in this case, i.e., from a first slot  15   a  to a sixth slot  15   f.    
   The rotor  2  has a rotor core  7  and a plurality of magnets (not shown) embedded in the rotor core  7 . A shaft (not shown) is inserted through and fixed by an axial hole of the rotor core  7 . In this case, the rotor core  7  is formed by stacking a large number of annular-shaped thin plates made of electromagnetic steel. 
   As shown in  FIG. 2 , each of the insulators  5  includes a peripheral wall  8 , a plurality of radially internally protruding portions  9  protruding from the peripheral wall  8 , and raised portions  10  provided at an end edge of the radially internally protruding portions  9  to face the peripheral wall  8 . The radially internally protruding portions  9  are arranged circumferentially at a predetermined pitch (at a pitch of 60°). One insulator  5  ( 5   a ) is fitted on one axial end surface of the core body  6 , while the other insulator  5  ( 5   b ) is fitted on the other end surface of the core body  6 . 
   The windings  4  consist of a U-phase winding  4   a , a V-phase winding  4   b  and a W-phase winding  4   c  as shown in  FIG. 4 . The U-phase winding  4   a  has a first magnetic pole portion U 1  and a second magnetic pole portion U 2 ; the V-phase winding  4   b  has a first magnetic pole portion V 1  and a second magnetic pole portion V 2 ; and the W-phase winding  4   c  has a first magnetic pole portion W 1  and a second magnetic pole portion W 2 . The U-phase winding  4   a , the V-phase winding  4   b  and the W-phase winding  4   c  are connected to one another via a neutral point N. At this time, as shown in  FIG. 1 , the first magnetic pole portion U 1  and the second magnetic pole portion U 2  of the U-phase winding  4   a  are placed in such a manner as to be symmetrical with each other with respect to a central axis of the stator core  3  so that they are opposite to each other; the first magnetic pole portion V 1  and the second magnetic pole portion V 2  of the V-phase winding  4   b  are placed in such a manner as to be symmetrical with each other with respect to the central axis of the stator core  3  so that they are opposite to each other; and the first magnetic pole portion W 1  and the second magnetic pole portion W 2  of the W-phase winding  4   c  are placed in such a manner as to be symmetrical with each other with respect to the central axis of the stator core  3  so that they are opposite to each other. 
   The winding method will be described in detail regarding the U-phase winding  4   a . As shown in  FIG. 5 , a part following a neutral wire  30  of the winding is wound around one of the opposed teeth T until after a tooth winding portion  11   a  serving as the second magnetic pole portion U 2  is provided. A crossover wire  31  to the other tooth T is extended to serve as a power wire  29 . Then, a part following the power wire  29  of the winding is wound around the other tooth T until after a tooth winding portion  11   b  serving as the first magnetic pole portion U 1  is provided. A winding end at the other tooth T is drawn out toward the neutral wire  30  so as to be connected to the neutral wire. That is, the neutral wire  30   a  on the winding start side of the tooth winding portion  11   a  serving as the second magnetic pole portion U 2  is connected to a neutral wire  30   b  on the winding end side of the tooth winding portion  11   b  serving as the first magnetic pole portion U 1  via the neutral point N. The same winding method as that of the U-phase winding  4   a  is applied to the other V-phase winding  4   b  and W-phase winding  4   c . Therefore, the second magnetic pole portion U 2 , V 2 , W 2  of each winding  4   a ,  4   b ,  4   c  has a lead-out portion  32  drawn out to the first magnetic pole portion U 1 , V 1 , W 1 , and the first magnetic pole portion U 1 , V 1 , W 1  has a lead-out portion  33  drawn out to the neutral wire  30  ( 30   b ). 
   The power wire  29  is fixed in such a manner that it is held between the tooth winding portion  11  and a slot bottom  21  (which is an inner circumferential surface defining the slot  15 ). That is, as shown in  FIG. 5 , the power wire  29  is held between the tooth winding portion  11   b  that constructs the second magnetic pole portion U 2 , and the slot bottom  21  corresponding to the tooth winding portion  11   b.    
   Next, as shown in  FIG. 3 , the peripheral wall  8  has a plurality of sub-walls  16  corresponding to the respective slots  15 . Of the slots, a first slot  15   a  corresponds to a first sub-wall  16   a , a second slot  15   b  corresponds to a second sub-wall  16   b , a third slot  15   c  corresponds to a third sub-wall  16   c , a fourth slot  15   d  corresponds to a fourth sub-wall  16   d , a fifth slot  15   e  corresponds to a fifth sub-wall  16   e , and a sixth slot  16   f  corresponds to a sixth sub-wall  16   f . The sub-walls  16  are each provided with a slit  24 , and the power wires  29  are received in the respective slits  24 . Specifically, the slit  24  is provided in the first sub-wall  16   a , whereby the first sub-wall  16   a  is divided into a first wall portion  22  and a second wall portion  23 . And, the power wire  29  drawn out and running along an inner surface of the sixth sub-wall  16   f  is then placed on an inner surface side of the first wall portion  22  of the first sub-wall  16   a  and then on an outer surface side of the second wall portion  23  of the first sub-wall  16   a . The sub-walls  16  each constitute a support portion, which will be described later. 
   In this case, a wiring separator  25  ( 25   a ) that supports the power wire  29  is provided between the sixth sub-wall  16   f  and the first sub-wall  16   a ; a wiring separator  25  ( 25   b ) that also supports the power wire  29  is provided between the first sub-wall  16   a  and the second sub-wall  16   b ; and a wiring separator  25  ( 25   c ) that also supports the power wire  29  is provided between the second sub-wall  16   b  and the third sub-wall  16   c . More specifically, a protrusion provided in a gap  26  between the sixth sub-wall  16   f  and the first sub-wall  16   a  forms the wiring separator  25   a ; a protrusion provided in a gap  27  between the first sub-wall  16   a  and the second sub-wall  16   b  forms the wiring separator  25   b ; and a protrusion provided in a gap  28  between the second sub-wall  16   b  and the third sub-wall  16   c  forms the wiring separator  25   c.    
   Thus, the power wires  29  pass the wiring separators  25   a ,  25   b , and  25   c , so that movement of the power wires toward the neutral wires  30  is restricted by these wiring separators  25   a ,  25   b , and  25   c . Therefore, a lead wire  20  (formed by bundling the power wires  29  of the U-, V-, and W-phases) can be drawn out in a state in which contact of the power wires  29  with the neutral wires  30  provided on the outer surface side of the peripheral wall  8  of the insulator  5  is prevented. The other insulator  5   b  on the counter-lead wire side is also provided with sub-walls  17 , but no wiring separators  25  ( 25   a ,  25   b ,  25   c ) are provided. This is because the power wires  29  are not drawn out to this insulator  5   b.    
   Each sub-wall  16  of the insulator  5  forms a support portion for supporting a protruding portion  35  of the tooth wiring portion  11  (see  FIG. 1 ) from its radially outer side, the protruding portion  35  being a portion that protrudes from an end surface of the stator core  3 . More specifically, the sub-walls (support portion)  16  have a height (i.e., an axial length) (H) (see  FIG. 3 ) set to be approximately equal to or slightly larger than the dimension of the protruding portion  35  of the tooth winding portion  11 . Furthermore, the sub-walls (support portion)  16  have a circumferential length (S) (see  FIG. 3 ) to accommodate the confronting circumferential edge portions of the circumferentially adjacent tooth winding portions  11 ,  11 . 
   This motor (which is of permanent magnet type) is used as, for example, a motor for a compressor of an air conditioner. The compressor includes a casing, which is a sealed container, a compressor elements part housed in the lower side of the sealed container, and a motor elements part housed in the upper side of the sealed container. The permanent magnet type motor is used for the motor elements part. Therefore, a shaft that is inserted through and fixed by the axial hole of the rotor  2  is a crankshaft for the compressor elements part, and the crankshaft is supported by a supporting member within the sealed container. 
   In the electric motor stator, since the power wire  29  drawn out from the tooth winding portion  11  of the winding  4  is fixed by being held between the tooth winding portion  11  and the slot bottom  21 , winding can be performed without wobbling of the power wire  29 . Therefore, it is possible to prevent the power wire  29  from being brought into contact with tooth winding portions  11  of other phases, so that the electric motor can exhibit a stable function as the motor for a long time. Further, the protective tube, which has conventionally been used, can be dispensed with, which makes it possible to provide an improvement in assembling performance and a reduction in costs. Further, since no complicated structure or arrangement for fixing the power wire  29  is required, a further cost reduction through simplification of the structure of the stator is possible. 
   Since the insulator  5  is provided with the winding separators  25  that keep the power wires  29  spaced from the neutral wires  30  by a predetermined distance, it is possible to prevent the power wires  29  from being brought into contact with the neutral wires  30 . Thereby, a motor with high quality can be provided. Moreover, wiring can securely be performed such that the power wires  29  are not brought into contact with the neutral wires  30  in the wiring operation, thus making it possible to contrive simplification of the wiring operation of the windings  4 . That is, the provision of the winding separators  25  in the insulator  5  makes it possible to achieve stable wiring workability and improve the non-contact reliability between the power wire  29  and the neutral wire  30 . Furthermore, since the insulator  5  has, on its radially outer side, the support portions formed of the sub-walls  16  of the peripheral wall  8 , the tooth winding portions  11  are thereby prevented from falling outward, so that the tooth winding portions  11  can maintain their stable winding state. Consequently, simplification of the winding operation can be achieved and a stator with high quality can be provided. Further, since the insulator  5  has, on its radially inner side, the raised portions  10 , it is also possible to prevent the protruding portions  35  of the tooth winding portions  11  from falling inward. 
   Embodiments of the invention being thus described, it will be obvious that the preset invention is not limited to those embodiments, but that same may be varied in many ways within the scope of the following claims. For example, it is possible to change the number of phases and the number of poles in the motor. The distance between the power wire  29  and the neutral wire  30  can be changed by changing the height of each protrusion forming the winding separator  25   a ,  25   b ,  25   c . Furthermore, the winding separators  25   a ,  25   b ,  25   c  may have the same or different heights.