Patent Publication Number: US-2023142308-A1

Title: Stator of rotating electrical machine and rotating electrical machine

Description:
TECHNICAL FIELD 
     The present invention relates to a stator of a rotating electrical machine, and a rotating electrical machine. 
     BACKGROUND ART 
     In order to manage the temperature of a motor, the temperature of a coil is managed because the coil is where a current flows in start-up and is most likely to reach high temperature. For example, PTL 1 (JP 2014-90546 A) discloses a rotating electrical machine including a rotor provided on a rotating shaft which is rotatably supported, and a stator disposed on an outer periphery of the rotor with a minute gap therebetween, the stator including a stator core having a plurality of slots formed and arranged along a circumferential direction, a stator winding wire to which a plurality of segment conductors that are inserted in the slots of the stator core are connected, and a thermistor that measures a temperature of the stator winding wire. The stator winding wire includes a slot portion accommodated in the slot, and a connecting portion that couples ends of the slot portions. The disclosed rotating electrical machine includes a temperature measuring element portion of the thermistor accommodated in a minute gap between the connecting portions of the segment conductor of the stator coil end (for example, see PTL 1). 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP 2014-90546 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     When measuring temperature at a neutral point including three neutral wires of a stator using a temperature sensor disposed on a V-phase stator winding wire which is the middle one among the three wires, temperature management is important in a state where electric currents flow only in coils of two phases other than the coil of which temperature is managed. The V-phase winding wire in the middle is sandwiched between the other U-phase winding wire and W-phase winding wire, and has a high following capability for temperature change since there is heat transfer between the winding wires, whereas each of the U-phase winding wire and the W-phase winding wire adjoins nothing on one side, and thus has a lower temperature than the v-phase winding wire in the middle. Thus, it is appropriate to manage temperature using the V-phase winding wire in the middle. 
     However, when dimensional differences in cross sections of the stator winding wires at the neutral point or a variation in positioning for a connecting work makes it difficult to reliably make the stator winding wire and the temperature sensor contact each other, a gap may be created between the temperature sensor and the stator winding wire, and make the contact between the temperature sensor and the stator winding wire unstable. To improve the temperature following capability of the temperature sensor, it is necessary that the temperature sensor reliably contacts a surface of a target to be measured. 
     An object of the present invention is to improve adhesion between a thermistor and a coil to improve temperature following capability of the thermistor. 
     Solution to Problem 
     A representative example of the invention disclosed in the present application is as follows. That is, a stator core, a stator winding wire configured with a plurality of connected segment coils attached to the stator core, and a temperature detection unit that is in contact with the segment coil to detect temperature are provided, and among the segment coils, a segment coil at which the temperature detection unit is disposed is disposed to protrude further than other segment coils disposed alongside. 
     Advantageous Effects of Invention 
     According to the present invention, adhesion between a temperature detection unit and a segment coil can be improved to improve temperature following capability. Problems, configurations, and effects other than those described above will be clarified by the following description of exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       [ FIG.  1   ]  FIG.  1    is a schematic view illustrating an overall configuration of a rotating electrical machine according to an exemplary embodiment of the present invention. 
       [ FIG.  2   ]  FIG.  2    is a perspective view illustrating a stator of the rotating electrical machine of the present exemplary embodiment. 
       [ FIG.  3   ]  FIG.  3    is a perspective view illustrating a structure of a neutral point of a stator winding wire according to the present exemplary embodiment. 
       [ FIG.  4   ]  FIG.  4    is a view of the neutral point of the present exemplary embodiment as viewed along an extending direction of a stator winding wire. 
       [ FIG.  5   ]  FIG.  5    is a view of the neutral point of the present exemplary embodiment as viewed along a radial direction. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG.  1    is a schematic view illustrating an overall configuration of a rotating electrical machine  1  according to an exemplary embodiment of the present invention. In  FIG.  1   , a cross section is taken for a portion of the rotating electrical machine  1  to illustrate an inside of the rotating electrical machine  1 . 
     As illustrated in  FIG.  1   , the rotating electrical machine  1  includes a housing  10 , a stator  2  including a stator core (stator iron core)  20  fixed to the housing  10 , and a rotor  3  rotatably disposed in the stator. A casing of the rotating electrical machine  1  includes a front bracket  11 , the housing  10 , and a rear bracket  12 . The housing  10   forms a water passage for cooling water of the rotating electrical machine  1  together with the water jacket  13 . 
     The rotor  3  is fixed to a shaft  31  supported by a bearing  30 A of the front bracket  11  and a bearing  30 B of the rear bracket  12 , and is rotatably held inside the stator core  20 . 
       FIG.  2    is a perspective view illustrating the stator  2  of the rotating electrical machine  1  of the present exemplary embodiment. 
     The stator  2  includes the stator core  20  having a plurality of slots formed along the circumferential direction, a stator winding wire  4 , and a temperature detection element  5  that measures the temperature of the stator winding wire  4 . 
     The stator core  20  is formed into an annular shape by stacking magnetic steel plates having a predetermined thickness along the axial direction. A plurality of slots extending in the axial direction is formed in the inner circumference of the stator core  20  along the circumferential direction. 
      The stator winding wire  4 , or the stator coil, is attached in the slots of the stator core  20  via an insulator  41  having a form of a sheet made of an insulating resin material. The stator winding wire  4  is made by inserting, along the axial direction, segment coils which are copper rectangular conductors  40  each having a form of a substantially U-shape in the slots of the stator core  20 , bending open ends of the rectangular conductors  40 , and electrically connecting the bent portions of the rectangular conductors  40  by welding or the like. 
     The welded portions of the rectangular conductors  40  are coated with an insulating resin material. By making the stator winding wire  4  with the rectangular conductors  40  in this manner, a larger gap can be made between wires of the stator winding wire  4  at coil ends  42  at both ends of the stator core  20  compared to a single continuous round wire conductor that is wound multiple times. Note that, in the rotating electrical machine  1  of the present exemplary embodiment, the stator winding wire  4  may be formed with a round wire conductor. 
     The stator winding wire  4  illustrated in  FIG.  2    is a winding wire of three-phase with a Y-connection, and includes a U-phase stator winding wire, a V-phase stator winding wire, and a W-phase stator winding wire formed of the rectangular conductors  40 . One end of the stator winding wire  4  of each of the phases, that is, the U-phase, the V-phase, and the W-phase is disposed as an output terminal  43 , and other ends of the respective stator winding wires  4  of the U-phase, the V-phase, and the W-phase are connected to form a neutral point  44 , whereby a three-phase AC circuit is formed. 
       FIG.  3    is a perspective view illustrating a structure of the neutral point  44  of the stator winding wire  4  of the present exemplary embodiment,  FIG.  4    is a view of the neutral point  44  as viewed along an extending direction of the stator winding wire  4 , and  FIG.  5    is a view of the neutral point  44  as viewed along a radial direction. 
     A temperature detection element  5  for measuring the temperature of the stator winding wire  4  is fixed to the neutral point  44  of the stator winding wire  4 . The temperature detection element  5  is a temperature sensor including a semiconductor whose electric resistance value changes along with a change in temperature. A control unit (for example, an inverter) of the rotating electrical machine  1  monitors the resistance value of the temperature detection element  5  to detect the temperature of the stator winding wire  4 . When the detected temperature of the stator winding wire  4  exceeds a predetermined upper limit value, the control unit limits or stops the performance of the rotating electrical machine  1  to prevent abnormal overheating of the stator winding wire  4 . 
     By heat transfer of the temperature of the stator winding wire  4  to the temperature detection element  5 , the temperature of the temperature detection element  5  changes and the electric resistance value of the temperature detection element  5  changes. When heat conduction from the stator winding wire  4  to the temperature detection element  5  is low, a time delay occurs in the temperature change of the temperature detection element  5 , that is, the change in the resistance of the temperature detection element  5  with respect to the temperature change of the stator winding wire  4 . 
     As described above, when a time delay occurs in the temperature change of the temperature detection element  5  with respect to the temperature change of the stator winding wire  4 , the stator winding wire  4  may be overheated. To prevent such overheating of the stator winding wire  4 , such measures is necessary as setting a specified value of the temperature of the stator winding wire  4 , which limits the performance of the rotating electrical machine  1 , to be smaller by a value corresponding to the time delay. However, taking such a measures, the rotating electrical machine  1  cannot sufficiently exhibit its performance. To let the rotating electrical machine  1  sufficiently exhibit its performance, the temperature following capability of the temperature detection element  5  to follow the temperature of the stator winding wire  4  needs to be enhanced. 
     To solve this problem, in the rotating electrical machine  1  of the present exemplary embodiment, a single segment coil 4B connected at the neutral point  44  is disposed to be displaced in a direction away from the stator core  20  and to protrude further than other segment coils  40 A and  40 C, and the temperature detection element  5  is disposed so as to contact the protruding segment coil  40 B. 
     For example, when the segment coil  40 B in the middle is disposed to be recessed from the segment coils  40 A and  40 C that are at ends, a gap may be created between the temperature detection element  5  placed at the neutral point  44  and the segment coil  40 B in the middle, and in such a case, the stator winding wire  4  and the temperature detection element  5  are not stably in contact with each other, which lowers the temperature following capability. In the present exemplary embodiment, by disposing the temperature detection element  5  so as to contact a side surface of the segment coil  40 B that is protruding, the temperature detection element  5  can be brought into close contact with the segment coil  40 B to enhance the temperature following capability of the temperature detection element  5 . 
     In particular, among the segment coils  40 A,  40 B, and  40 C connected at the neutral point  44 , it is preferable that the segment coil  40 B in the middle protrudes further than the other segment coils  40 A and  40 C. The segment coils  40 A and  40 C at the ends easily dissipate heat to the outside, and thus tend to have a lower temperature. When the segment coils  40 A and  40 C at the ends are protrudingly disposed and the temperature detection element  5  is provided on the segment coils  40 A and  40 C, the measured temperature will be of the segment coils  40 A and  40 C at the ends and having a lower temperature than the temperature of the segment coil  40 B in the middle, so that the temperature of a high-temperature portion of the neutral point  44  cannot be measured. Accordingly, in the present exemplary embodiment, the temperature of the segment coil  40 B, which is a portion that becomes high-temperature in the neutral point  44 , can be managed, and the rotating electrical machine  1  can be appropriately controlled to extend the life of the rotating electrical machine  1 . 
     As illustrated in  FIG.  4   , an adhesive layer  6  is preferably provided between the temperature detection element  5  and the segment coil  40 B. It is preferable that the adhesive layer  6  is an acrylic adhesive, and has a double-sided tape-like structure. A tape constituting the adhesive layer  6  may preferably have a size that is, in a width direction, the same as the segment coil  40 B or smaller than the temperature detection element  5  but larger than the segment coil  40 B and, in a longitudinal direction, equal to or slightly smaller (for example, about 1.0 mm) than the temperature detection element  5 . The adhesive layer  6  avoids including an air layer having poor thermal conduction between the temperature detection element  5  and the segment coil  40 B and enhances the temperature following capability of the temperature detection element  5 . 
     As illustrated in  FIG.  5   , distal ends of the segment coils  40 A,  40 B, and  40 C at the neutral point  44  are welded, the segment coils  40 A,  40 B, and  40 C are arrayed for welding at the arrayed section  44 A, and the segment coil  40 B in the middle has a plastically deformed portion in a deformed section  44 B in the rear of the arrayed section  44 A, the plastically deformed portion forming a protruding shape toward a temperature detection region  44 C where the temperature detection element  5  is disposed. As described above, since the segment coil  40 B in the middle is plastically deformed in the deformed section  44 B between the arrayed section  44 A and the temperature detection region  44 C so as to form protruding, at which the temperature detection element  5  is disposed, in the temperature detection region  44 C, a protruding portion at which the temperature detection element  5  is disposed can be formed without performing welding in a state where the segment coils  40 A,  40 B, and  40 C are disposed with a displacement therebetween, without reducing a cross sectional area for welding, and with the welding strength maintained. 
     As described above, according to the exemplary embodiment of the present invention, the stator core  20 , the stator winding wire  4  configured with a plurality of connected segment coils attached to the stator core  20 , and the temperature detection unit (temperature detection element  5 ) that contacts the segment coils  40 B to detect temperature are provided, and the segment coil  40 B at which the temperature detection unit  5  is disposed is disposed so as to protrude further than the other segment coils  40 A and  40 C disposed alongside, so that the segment coil  40 B in the middle is not recessed from the other segment coils  40 A and  40 C even if there are dimensional differences in cross sections of the segment coils or a variation in positioning for a connecting work, and this makes the temperature detection unit  5  to stably contact the segment coil  40 B and improves temperature following capability, which enables appropriate management of the temperature of the motor. 
     In addition, at least the three segment coils  40 A,  40 B, and  40 C are disposed alongside, and the second segment coil  40 B disposed between the first segment coil  40 A and the third segment coil  40 C protrudes further than the first segment coil  40 A and the third segment coil  40 C. That is, since the segment coil  40 B disposed in the middle is connected so as to protrude high, the segment coil  40 B of which temperature becomes high is brought into stable contact with the temperature detection unit  5 , and thus the temperature of the rotating electrical machine  1  can be accurately measured. 
     In addition, the first segment coil  40 A, the second segment coil  40 B, and the third segment coil  40 C, which allow currents of different three phases (U, V, and W) flow, are connected at the neutral point  44 , the second segment coil  40 B among the three segment coils  40 A,  40 B, and  40 C constituting the neutral wire  44  is disposed to be further displaced in a direction perpendicular to the extending direction than the first segment coil  40 A and the third segment coil  40 C, and the temperature detection unit  5  is disposed at a side surface of the second segment coil  40 B, so that even when only the U-phase segment coil  40 A and the W-phase segment coil  40 C at the ends have no current flowing therein and the segment coil  40 B in the middle has a current flowing therein, the temperature of the rotating electrical machine  1  can be accurately measured to appropriately control the rotating electrical machine  1 , and the life of the rotating electrical machine  1  can be extended. 
     In addition, the adhesive layer  6  is provided between the temperature detection unit  5  and the segment coil  40 B, and the adhesive layer  6  is formed to have the same size as the segment coil  40 B or a size larger than the segment coil  40 B but smaller than the temperature detection unit  5  in a view along the extending direction of the segment coil  40 B. That is, the problem that the position of the temperature detection unit  5  cannot be fixed by simply placing the temperature detection unit  5  on the segment coil  40 B can be solved, and thus the temperature detection unit  5  can be fixed at an appropriate position. In addition, by filling the space between the segment coil  40 B and the temperature detection unit  5  with the adhesive layer  6 , a region occupied by air having a low thermal conductivity is reduced, and thus heat transfer from the segment coil  40 B to the temperature detection unit  5  can be improved. In addition, adhesive force between the temperature detection unit  5  and the segment coil  40 B can be improved by maximizing an adhesive area of the adhesive layer  6 . 
     In addition, provided with the arrayed section  44 A in which the end portions of the first segment coil  40 A, the second segment coil  40 B, and the third segment coil  40 C are connected, the temperature detection unit  5  in which the temperature detection unit  5  is disposed at a side surface of the second segment coil  40 B, and the deformed section  44 B which is between the arrayed section  44 A and the temperature detection unit  5  and in which the second segment coil  40 B is deformed so as to form protruding in the temperature detection region  44 C and extend in a direction different from the other segment coils  40 A and  40 C, a protruding portion at which the temperature detection element  5  is disposed can be formed without performing welding in a state where the segment coils  40 A,  40 B, and  40 C are disposed with a displacement therebetween, without reducing a cross sectional area for welding, and with the welding strength maintained. 
     Note that the present invention is not limited to the above-described exemplary embodiments, and includes various modifications and equivalent configurations within the spirit of the appended claims. For example, the above-described exemplary embodiments have been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the described configurations. Further, a part of the configuration of an exemplary embodiment may be replaced with a configuration of a different exemplary embodiment. Further, a configuration of a different exemplary embodiment may be added to the configuration of an exemplary embodiment. 
     In addition, for each exemplary embodiment, a part of a configuration may be eliminated or replaced with a configuration of a different exemplary embodiment, or a configuration of a different exemplary embodiment may be added. 
     REFERENCE SIGNS LIST 
     
         
           1  rotating electrical machine 
           2  stator 
           3  rotor 
           4  stator winding wire 
           5  temperature detection element 
           6  adhesive layer 
           10  housing 
           11  front bracket 
           12  rear bracket 
           13  water jacket 
           20  stator core 
           30 A bearing 
           30 B bearing 
           31  shaft 
           40  rectangular conductor 
           40 A,  40 B,  40 C segment coil 
           41  insulator 
           42  coil end 
           43  output terminal 
           44  neutral point 
           44 A arrayed section 
           44 B deformed section 
           44 C temperature detection region