JP2014007794A - Method for bonding conductor of rotary electric machine and coil of rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase in a size of a part to which edges of different segment conductors are to be bonded, when edges of different segment conductors are bonded to form a coil of a rotary electric machine by using a plurality of segment conductors.SOLUTION: Two segment conductors 7 to be joined, are held in a state that opposing surfaces Po of a conductor edge 7t are adjacent and opposed to each other and end surfaces 7p for bonding that are apical surfaces of the conductor edge 7t are arranged along a reference plane Pr, a tabular conductive plate 10 is arranged so as to contact with both of two end surfaces 7p for bonding of segment conductors 7, and the conductive plate 10 and two end surfaces 7p are welded by irradiating an irradiation surface 10b with a laser from the irradiation surface 10b side, which is opposite to a contact surface 10t where the conductive plate 10 contacts with end surfaces 7p for bonding.

Description

  The present invention relates to a method for joining end portions of different segment conductors to form a coil of a rotating electrical machine using a plurality of segment conductors. Moreover, it is related with the coil formed by joining the edge parts of a segment conductor.

  As a method of arranging a coil conductor wire in a rotating electrical machine, there is a method using a conductor called a segment conductor (segment coil). In this method, for example, a plurality of segment conductors configured by a flat wire bent in a pine needle shape or a U-shape are inserted in the axial direction into a slot formed in a magnetic core. Then, on the open side of the segment conductor, the open ends of the other overlapping segment conductors are joined together to form a continuous coil. As described in Japanese Patent Application Laid-Open No. 2008-154433 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2004-25303 (Patent Document 2), segment conductors are often joined by TIG welding (a type of arc welding). Tungsten Inert Gas welding) is used (Patent Document 1: 2-3, 36-37, FIG. 1-2, etc., Patent Document 2: 3rd, FIG. 1, etc.).

  By the way, in general, an insulating coating is applied to the surface of the segment conductor. However, during welding, the insulating coating at the end of the segment conductor to be joined is removed (Patent Document 1: sixth paragraph). Patent Document 2: FIG. 1 and the like). Further, since the heat generated during welding propagates through the segment conductor, a certain range of insulating coating is also removed from the directly welded portion. If the heat generated during welding is high, the range in which heat is conducted is widened, and the length of the bare wire is increased by removing the insulating film in order to prevent melting of the insulating film. The bare wire portion constitutes a coil end protruding in the axial direction of the core. Accordingly, when the bare wire portion becomes longer, the coil end becomes longer in the axial direction, which hinders downsizing of the rotating electrical machine. Moreover, since the total extension of the conductor wire which comprises a coil also becomes long, material cost and copper loss may increase.

JP 2008-154433 A JP 2004-25303 A

  In view of the above background, when a plurality of segment conductors are used and ends of different segment conductors are joined together to form a coil of a rotating electrical machine, enlargement of the joined portions is suppressed, and the coils are downsized. A technique that can do this is desired.

  In view of the above problems, the characteristic configuration of the conductor joining method for a rotating electrical machine according to the present invention is to use a plurality of segment conductors coated with an insulating coating around the conductor extending direction to form a coil of the rotating electrical machine. , A conductor joining method for a rotating electrical machine that joins the conductor ends that are the ends of the different segment conductors, and the two conductors that are the conductors to be joined are adjacent to each other at the opposing surfaces of the conductor ends. A conductor holding step for holding the end faces for joining, which are the front end faces of the conductor end portions, in a state of being aligned along a reference plane, and the two end faces for joining of the segment conductors to be joined conductors From the side of the irradiation surface which is the surface opposite to the contact surface where the conductive plate is in contact with the joining end surface, the plate installation step of installing a plate-like conductive plate so as to contact both By irradiating a laser on the irradiation surface lies in and a laser irradiation step of welding the respective said conductive plate and two of the bonding end face.

  In welding using a laser, energy for melting the segment conductor can be given to a narrow region at a higher density than in arc welding. As a result, it is possible to reduce the change in the conductor shape caused by melting the conductor more than necessary and then solidifying. Furthermore, according to this characteristic structure, the electroconductive plate installed so that the end surface for joining of the segment conductor used as a joining object conductor may be contacted, and the end surface for joining may be welded. Therefore, welding can be performed with little or no removal of the insulating coating applied around the conductor in the extending direction. Moreover, in general joining, since the side surfaces of the conductors from which the insulating coating has been removed are welded, a length for welding is required in the extending direction of the segment conductors. The length for this welding affects the length of the end (coil end) of the coil of the rotating electrical machine. That is, when the side surfaces facing each other along the extending direction of the segment conductor are joined, the coil end increases accordingly. However, according to this feature configuration, the coil end can be reduced in size because only the conductive plate is installed ahead of the tip (end surface for joining) along the extending direction of the segment conductor. It becomes. As a result, it is possible to reduce the material cost of the segment conductor and the copper loss. Thus, according to this characteristic configuration, when a plurality of segment conductors are used and the ends of different segment conductors are joined together to form a coil of a rotating electrical machine, the enlargement of the joined parts is suppressed, The coil can be reduced in size.

  The coil of the rotating electrical machine that can be miniaturized as described above is configured with the following features. That is, the characteristic configuration of the coil of the rotating electrical machine according to the present invention uses a plurality of segment conductors coated with an insulating film around the extending direction of the conductors, and the conductor end portions which are the end portions of the different segment conductors. A coil of a rotating electrical machine formed by joining, and the two segment conductors to be joined conductors are opposed to each other with opposing surfaces of the conductor end portions adjacent to each other, and a tip end surface of the conductor end portion In the state where the joining end faces are aligned along a reference plane, a plate-like conductive plate installed so as to contact both of the two joining end faces of the segment conductors to be joined conductors The conductive plate and the conductive plate are separated by two lasers irradiated to the irradiation surface from the irradiation surface side opposite to the surface in contact with the bonding end surface. It lies in each and the bonding end faces are welded.

  Here, in the conductor joining method for a rotating electrical machine according to the present invention, the conductive plate has a size that fits inside an arrangement region of the two joining end faces when viewed from a direction orthogonal to the reference plane. Is preferred. In the coil of the rotating electrical machine according to the present invention, it is preferable that the conductive plate has a size that fits inside the region where the two end surfaces for joining are viewed from a direction orthogonal to the reference plane. . When arc welding or the like is used, the conductor ends of the segment conductors are greatly melted. The melted conductor is liable to be liquefied, so that the surface tension acts and it is easy to be rounded. As a result, the protrusion to the side perpendicular to the extending direction of the segment conductor is likely to occur. This lateral protrusion reduces the distance between the conductor ends of the segment conductors. In order to secure the insulation distance between the conductor end portions, if the gap between the conductor end portions is increased in consideration of the protrusion, it is not preferable for downsizing and the magnetic performance is also affected. In laser welding, energy can be applied to a limited area. Therefore, it is possible to accurately weld the conductive plate and each of the joining end surfaces of the two segment conductors. Therefore, when the size of the conductive plate is a size that fits inside the arrangement region of the two end faces for joining as viewed from the direction orthogonal to the reference plane, the conductive plate is orthogonal to the extending direction of the segment conductors. There is no protrusion to the side. As a result, the coil can be reduced in size.

  As described above, in welding using a laser, energy can be applied in a concentrated area. Therefore, it is possible to accurately weld the conductive plate and each of the joining end surfaces of the two segment conductors. It is preferable that the conductive plate and each segment conductor are welded at a plurality of locations because the mechanical strength is increased and the impedance is reduced electrically. Therefore, as one aspect, in the laser irradiation step of the conductor bonding method for a rotating electrical machine according to the present invention, it is preferable to irradiate a plurality of locations in a region corresponding to one end surface for bonding on the irradiation surface. is there.

  Further, in the laser irradiation step of the conductor joining method for a rotating electrical machine according to the present invention, the laser irradiation is stopped for a predetermined stop time and an irradiation phase for laser irradiation for a predetermined specified irradiation time. It is preferable that the laser is irradiated by pulse irradiation that repeats the pause phase. Even when laser welding is used, the amount of energy applied increases as the laser irradiation time increases, and the temperature rise increases. When pulse irradiation is performed in the laser irradiation process, in the rest period, the heat of the already melted region (melted region) is propagated to the non-melted region adjacent to the melted region to reduce the heat of the melted region, and the entire temperature. The rise can be suppressed. In the next irradiation phase, energy is added to the melting region and the non-melting region preheated adjacent to the melting region, so that the melting region can be easily expanded. That is, a necessary region can be melted while suppressing the overall temperature rise.

  Here, it is preferable that the specified irradiation time in the pulse irradiation is set to be less than a time in which the temperature of the segment conductor that increases with laser irradiation reaches the softening temperature of the insulating coating. As described above, by performing pulse irradiation, it is possible to melt a necessary region while suppressing an overall temperature increase. At this time, if the specified irradiation time is set based on the softening temperature of the insulating coating, the peeling length of the insulating coating can be set appropriately, and the coil end can be downsized.

The perspective view of the stator provided with the coil which concerns on this invention The perspective view of the phase coil which comprises a coil Perspective view of basic segment conductors composing coil Flow chart showing an example of a method for joining segment conductors Explanatory drawing which shows typically an example of the joining method of a segment conductor Comparison between arc welding and laser welding Waveform diagram showing the relationship between pulse irradiation and conductor temperature Top view showing another example of conductive plate Top view showing another example of conductive plate

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the case where the coil 3 of the rotating electrical machine according to the present invention is applied to the stator 1 of the inner rotor type rotating electrical machine as shown in FIG. 1 will be described as an example. This rotating electric machine is a multiphase AC rotating electric machine (here, a three-phase AC rotating electric machine). The coil 3 includes a phase coil 31 having one phase as shown in FIG. 2 and a plurality of phases (here, U phase, V phase, and W phase). Since the phase coil 31 of each phase included in the coil 3 has the same configuration, the phase coil 31 of each phase will be described below without particular distinction. In the following description, the direction along the arrow “L” is referred to as “axial direction” and the direction along the arrow “C” is referred to as “circumferential” with reference to the axial center of the cylindrical core reference surface 21 of the stator 1 shown in FIG. The direction along “direction” and the arrow “R” will be referred to as “radial direction”.

  Although there are wave winding and lap winding in the manner of winding the conductor wire for constituting the coil, this embodiment exemplifies lap winding. For example, as shown in FIG. 2, each phase coil 31 includes a plurality of lap winding sets 6 each having a lap winding portion 32 and a circumferential connection portion 5. The lap winding portion 32 refers to a portion formed by winding a conductor on the same axis a plurality of times, and the circumferential connection portion 5 is constituted by a conductor having at least one end connected to the lap winding portion 32. Refers to the part. In the present embodiment, one lap winding set 6 includes a plurality (four in this case) of lap winding portions 32 arranged at a constant pitch (lap winding portion arrangement pitch) along the circumferential direction, and the lap winding set 6. It is comprised by the circumferential direction connection part 5 which connects between the winding parts 32. FIG.

  Specifically, the phase coil 31 is arranged so as to be shifted from each other in the circumferential direction, the first lap winding set 61, the second lap winding set 62, the third lap winding set 63, and the fourth lap winding set 64. And. In the present embodiment, the first lap winding set 61, the second lap winding set 62, the third lap winding set 63, and the fourth lap winding set 64 are all in the same shape. The end portion of the lap winding set 6 is connected to the circumferential connection portion 5 for connecting the end portion to a power line connected to a power source, a neutral point or the like, or to the lap winding set 6 having a different phase. A circumferential connection 5 for connection is connected.

  Specifically, as shown in FIGS. 1 and 2, one end portion of the first lap winding set 61 is connected to a first circumferential connection portion 51 for connecting the end portion to a power line. The second end portion of the first overlap winding set 61 is connected to the second circumferential connection portion 52 for connecting the other end portion and one end portion of the second overlap winding set 62. . In addition, a third circumferential connecting portion 53 for connecting the one end portion and one end portion of the third overlapping winding set 63 is connected to one end portion of the fourth overlapping winding set 64, A fourth circumferential connection portion 54 for connecting the other end portion to the neutral point is connected to the other end portion of the fourth overlapping winding set 64. Further, in the second overlap winding set 62, the other end opposite to the one end to which the second circumferential connection portion 52 is connected is the third overlap connection portion in the third overlap winding set 63. The connecting member 90 is connected to the other end opposite to the one end to which 53 is connected. That is, in the example shown in the present embodiment, the first lap winding set 61, the second lap winding set 62, the third lap winding set 63, and the fourth lap winding set 64 are described from the power line toward the neutral point. Are connected in series. As shown in FIG. 1, the coil 3 including the three phase coils 31 configured as described above is wound around the stator core 2 included in the stator 1 by lap winding as a whole.

  In the present embodiment, the entire overlapping winding set 6 including the overlapping winding part 32 is configured by joining a plurality of segment conductors 7. The segment conductor 7 includes a basic segment conductor 7 a that constitutes the lap winding portion 32 and a deformed segment conductor that constitutes the circumferential connection portion 5. The connecting member 90 is also included in the broad segment conductor 7. Here, as a representative of the segment conductor 7, a basic configuration of the most frequently used basic segment conductor 7a will be described with reference to FIG.

  The segment conductor 7 is a conductor corresponding to the phase coil 31 divided into a plurality of parts, and the phase coil 31 is configured by joining ends of the plurality of segment conductors 7. As shown in FIG. 3, the segment conductor 7 is a rectangular linear conductor (a rectangular wire having a rectangular cross-section shape orthogonal to the extending direction substantially equivalent to the energizing direction, more specifically, a corner having an arc shape. ). Further, the segment conductor 7 basically has the same cross-sectional shape regardless of the position in the extending direction, except for the bent portion. The linear conductor is made of a metal such as copper or aluminum, for example, and the surface of the linear conductor (especially the periphery in the extending direction) is covered with an insulating film made of a resin such as enamel or polyimide.

  When the segment conductor 7 is attached to the stator core 2, the pair of conductor side portions 71 disposed in the slot 22 formed between the teeth 23 and the pair of conductor side portions 71 are arranged between the pair of conductor side portions 71. A conductor transition portion 72 connected on the outside along the direction, and a protrusion 73 that extends from each of the pair of conductor side portions 71 and projects from the stator core 2 in the axial direction on the opposite side of the conductor transition portion 72 in the axial direction. I have. The two distal end portions 74 which are open ends in the protruding portion 73 are formed such that, when attached to the stator core 2, the extending direction thereof is parallel to the axial direction and parallel to each other along the radial direction. In the present embodiment, the tip portions 74 adjacent to each other in the radial direction of the pair of segment conductors 7 serving as conductors to be joined are joined in the radial direction.

  The lap winding portion 32 is configured such that a plurality of conductor side portions 71 are disposed in each of the pair of slots 22 and wound a plurality of times between the pair of slots 22. In the present embodiment, the lap winding portion 32 uses a plurality of basic segment conductors 7 a that can be inserted in the axial direction with respect to the slot 22, and the protrusions 73 that protrude in the axial direction from the stator core 2 of the basic segment conductor 7 a. The tip portions 74 are joined together. In addition, the basic segment conductor 7a can be said to be a conductor corresponding to a portion obtained by dividing the lap winding portion 32 into a plurality of portions per round. As shown in FIG. 2, the lap winding portion 32 is formed using four basic segment conductors 7 a in which the conductor side portions 71 on both sides in the circumferential direction are arranged in the same slot 22. Then, the end portions 74 of the basic segment conductors 7a adjacent to each other in the radial direction are sequentially joined to form the lap winding portion 32. In the present embodiment, the four basic segment conductors 7a constitute the lap winding portion 32 that winds between the pair of slots 22 four times.

  Heretofore, the configuration of the basic segment conductor 7a and the lap winding portion 32 configured using the basic segment conductor 7a have been described as representatives. Similarly to the basic segment conductor 7a, the circumferential direction connection portion 5 and the connection member 90 constituting the segment conductor 7 also have an extending direction parallel to the axial direction at the time of attachment to the stator core 2, and along the radial direction. Thus, a tip portion formed so as to be parallel to the tip portion 74 of the basic segment conductor 7a is formed. When the basic segment conductor 7a and the circumferential connection portion 5 are joined, the distal end portion 74 of the basic segment conductor 7a and the distal end portion of the circumferential connection portion 5 are joined. Further, when the basic segment conductor 7a and the connecting member 90 are joined, the distal end portion 74 of the basic segment conductor 7a and the distal end portion of the connecting member 90 are joined.

  Hereinafter, a method of joining the basic segment conductors 7a to each other, or the basic segment conductor 7a and the circumferential connecting portion 5, or the basic segment conductor 7a and the connecting member 90 will be described. In this method, a plurality of segment conductors 7 provided with an insulating coating 7h are used to join the conductor end portions 7t, which are the end portions of different segment conductors 7, in order to form the coil 3 of the rotating electrical machine. This is a method, and the shape of the segment conductor 7 is not limited to the above-described form. Needless to say, the present invention is not limited to such a lap winding segment conductor, but can be applied to the case where wave winding segment conductors are joined together.

  As shown in FIG. 4, this joining method has three major steps. The first step is conductor holding step # 10. In the conductor holding step # 10, as shown in FIG. 5, the two segment conductors 7 that are conductors to be joined are opposed to each other with the opposing surfaces Po of the conductor end portions 7t facing each other, and the tip end surfaces of the conductor end portions 7t. The joining end faces 7p are held in a state of being aligned along the reference plane Pr. In the conductor holding step # 10, the segment conductor 7 is held by a clamping jig 100 as schematically shown in FIG. The segment conductor 7 is a conductor in which an insulating coating 7h is applied around the extending direction of the conductor. Here, it is assumed that the base material of the conductor is exposed on the joining end face 7p. In the present embodiment, since the insulating coating 7h is not applied to the joining end face 7p, the step of removing the insulating coating 7h of the segment conductor 7 prior to welding is not provided. However, it does not prevent the insulating coating 7h in the region having a predetermined peeling length from being removed from the bonding end face 7p as necessary.

  The second process is a plate installation process # 15 in which the plate-like conductive plate 10 is installed so as to come into contact with both of the two joining end faces 7p of the segment conductor 7 to be joined. The conductive plate 10 is preferably made of the same material as the segment conductor 7. The bonding end surface 7p with which the conductive plate 10 contacts is preferably a flat surface with little unevenness, but does not prevent the uneven surface from being uneven. As will be described later, the conductive plate 10 and each of the two joining end faces 7p are welded using a laser. During welding, since the conductive plate 10 and the segment conductor 7 are mixed in the welding region, the gap between the joining end surface 7p and the contact surface 10t of the conductive plate 10 (gap caused by unevenness) is eliminated. .

  The conductive plate 10 has a size that fits inside the arrangement region of the two joining end faces 7p when viewed from the direction orthogonal to the reference plane Pr. The arrangement region is a closed region configured by connecting the outer edges of the two joining end surfaces 7p excluding the opposing surface Po, and a region occupied by the two joining end surfaces 7p and a region sandwiched between them ( And a region corresponding to the gap when the gap is generated between the segment conductors 7). For example, the arrangement area is an area corresponding to the symbol “S” shown in FIGS. 6, 8, and 9. The conductive plate 10 shown in FIGS. 5 and 6 has substantially the same size as the arrangement area S and is arranged so as to coincide with the arrangement area S.

  In the third step, the conductive plate 10 is irradiated with a laser beam from the irradiation surface 10b side opposite to the contact surface 10t where the conductive plate 10 contacts the bonding end surface 7p. And laser irradiation step # 20 of welding the two joining end faces 7p. As illustrated in FIG. 5, the laser irradiation step # 20 includes a step of performing laser irradiation for welding the joining end surface 7p of one segment conductor 7 and the conductive plate 10, and a joining of the other segment conductor 7. This is performed at least twice including the step of performing laser irradiation for welding the end face 7p and the conductive plate. FIG. 5 shows an example in which the laser is irradiated at an irradiation angle such that the optical axis of the laser is substantially perpendicular to the irradiation surface 10b or the reference plane Pr. For example, the laser may be irradiated at 2 to 3 [°].

  Further, it is preferable that the focal point of the laser irradiated in the laser irradiation step # 20 is set on the irradiation surface 10b of the conductive plate 10. The molten conductor is irradiated with a laser having a high energy density, and good welding can be realized. However, the focal point of the laser does not prevent the laser beam from being set flexibly similarly to the irradiation angle. The focal point may be at least the segment conductor 7 side (downward in FIG. 5) from the irradiation surface 10b of the conductive plate 10. As will be described later, in the laser welding of the present embodiment, melting proceeds from the inside of the object. Accordingly, when the focal point is set below the irradiation surface 10b in the drawing, a laser having a high energy density is irradiated to the previously melted portion, and thus good welding can be realized.

  In the welding using a laser, it is possible to concentrate and give energy to a limited area as will be described later. Therefore, it is possible to weld the conductive plate 10 and each of the joining end faces 7p of the two segment conductors 7 with high accuracy. And if the electroconductive plate 10 and each segment conductor 7 are welded in multiple places, since mechanical strength will also become high and an impedance will fall electrically, it is suitable. Therefore, in the laser irradiation step # 20, it is preferable to irradiate a plurality of locations in the region corresponding to one joining end surface 7p on the irradiation surface 10b. FIG. 6 shows an example in which laser is applied to six locations in a region H corresponding to one joining end face 7p. Of course, if mechanical and electrical sufficient welding is possible, the structure may be such that one laser is irradiated to each region H corresponding to one joining end face 7p.

  As described above, the laser irradiation angle is not limited to being perpendicular to the irradiation surface 10b and the reference plane Pr. When a plurality of locations in the region corresponding to one joining end surface 7p are irradiated with laser on the irradiation surface 10b, the irradiation angles for the plurality of locations may be different. For example, it is preferable that the laser is irradiated at an irradiation angle such that the optical axis of the laser is directed from the outer edge side to the inner side at a bonding portion set near the outer edge of the bonding end surface 7p. It is possible to suppress the melting region from reaching the side surface along the extending direction of the segment conductor 7 and realize mechanically and electrically strong welding. On the other hand, it is desirable that the melted region grows straight along the extending direction of the segment conductor 7 at the joining portion set at the center of the joining end face 7p. Therefore, it is preferable that the laser beam is irradiated at the joining portion in a direction along the extending direction of the segment conductor 7, for example, at an irradiation angle close to a right angle with respect to the irradiation surface 10b and the reference plane Pr.

  Incidentally, laser irradiation methods used for laser welding include an irradiation mode called a single mode and an irradiation mode called a multimode. An irradiation mode called a single mode is a mode that uses laser light amplified by a single excitation light. In the single mode, the energy distribution is a Gaussian distribution, the diameter of the laser beam can be reduced, and the energy density can be increased. On the other hand, in an irradiation mode called multimode, laser light amplified by a plurality of excitation lights is used. The multimode energy distribution is a top-hat type distribution in which the diameter of the isosceles base is rotated about a straight line passing through the midpoints of the upper and lower bases. For this reason, although an output can be enlarged, the diameter of a laser beam becomes large (thick). In the present embodiment, since the joining end face 7p of the segment conductor 7 and the conductive plate 10 are joined through the conductive plate 10, it is preferable to apply energy to a narrow region at a high density. Therefore, the single mode is adopted as the irradiation mode.

  When the conductive plate 10 is irradiated with the laser in the single mode, the base material of the conductive plate 10 or the segment conductor 7 is vaporized, and melting starts from the inside of the base material. As laser irradiation continues further, the melting region gradually expands from the inside of the base material. The single mode melts from the inside of the base material and spreads into a narrow and deep region, and is therefore suitable for applications in which the conductive plate 10 and the segment conductor 7 are joined so as to be skewered.

  On the other hand, in multi-mode, it melts from the surface of the base material and melts in a wide and shallow region. As a result, the conductive plate 10 and the segment conductor 7 are not joined so as to be skewered, and the molten conductive plate 10 is joined so as to cover the conductor end portion 7t including the joining end face 7p of the segment conductor 7. there is a possibility. For this reason, there is a possibility that the conductor end portion 7t of the welded segment conductor 7 is enlarged, and therefore, in this embodiment, the single mode is adopted as the irradiation mode.

  In addition, according to experiments by the inventors, it has been confirmed that, in the single mode, a high energy density can be maintained even when the focal length of the laser is increased. For this reason, it becomes possible to separate the laser head 200 from the conductors to be joined, and it becomes easy to secure a work distance during welding, so that productivity is improved. Of course, the larger the output of the laser, the faster the conductive plate 10 and the segment conductor 7 melt. Then, when the conductive plate 10 and the base material of the segment conductor 7 are in a liquid state, reflection is reduced and the laser energy absorption rate is also increased. Therefore, the laser output is preferably set to 2000 [W] or more, for example. As a preferred embodiment, the laser wavelength is preferably 0.3 to 1.1 [μm] and the focal spot diameter is 10 to 200 [μm].

  FIG. 6 is a diagram comparing conventional welding by arc discharge (TIG welding) and laser welding according to the present embodiment. In welding by arc discharge, the bare conductor end portions 7n from which the insulating coating 7h in the region of the separation length Lp (Lp2) defined in advance is removed from the tip of the conductor end portion 7t are joined together. That is, the two segment conductors 7 that are conductors to be joined are welded in a state where the opposing surfaces of the bare conductor end portions 7n are adjacent to each other and the tips of the bare conductor end portions 7n are aligned along the reference plane Pr. Is done. In the case of performing TIG welding, it is necessary to peel off the insulating coating 7h as described above. However, in the case of performing laser welding using the conductive plate 10, it is not necessary to strip off the insulating coating 7h. Alternatively, it is sufficient to peel the insulating coating 7h in the range of the slight peeling length Lp from the tip of the conductor end 7t.

  The middle and lower stages of FIG. 6 schematically show the segment conductors 7 after welding. When TIG welding is performed, the arc AK is applied to a relatively wide range of the tip of the segment conductor 7, the tip is melted as a whole, and the tip is rounded and solidified by surface tension. . For this reason, the outer edge of the tip of the conductor end portion 7t after joining seen from the direction (upper surface) orthogonal to the reference plane Pr protrudes from the arrangement region S of the tips of the two conductor end portions 7t before joining. That is, the contour line after welding has a partially protruding shape with respect to the contour line at the tip of the conductor end 7t before welding. For this reason, in the case of TIG welding, it is necessary to increase the distance “Cp” between the adjacent conductors to be joined by this protrusion amount “Ms” so as to ensure an insulation distance.

  On the other hand, in the case of laser welding using the conductive plate 10, the distance “Cp” between adjacent conductors to be joined is relatively short because it is not necessary to consider the protrusion amount “Ms”. . Therefore, when laser welding using the conductive plate 10 is performed, the coil 3 can be downsized as compared with the case where TIG welding is performed. The conductive plate 10 has a size that fits inside the arrangement region S of the two joining end faces 7p when viewed from the direction orthogonal to the reference plane Pr. Therefore, the coil 3 formed by using the joining method of the present embodiment is disposed after joining the inside of the arrangement region S at the tips of the two conductor end portions 7t before joining, when viewed from the direction orthogonal to the reference plane Pr. The outer edge of the tip end of the conductor end portion 7t is accommodated. That is, the outer edges of the tips of the two conductor end portions 7t corresponding to the arrangement region S do not change before and after joining.

  As described above, when TIG welding is performed, the tip of the segment conductor 7 is melted as a whole, and the tip is rounded and solidified by surface tension. Therefore, the conductor end portion 7t of the segment conductor 7 after welding may be extended by the extension amount “Mu” from the reference plane Pr along the extending direction as shown in the side view of the lower stage of FIG. . For this reason, there is a possibility that the segment conductor 7 becomes longer by the stretch amount “Mu” at the conductor end 7t. Furthermore, as described above, in the case of TIG welding, the temperature of the segment conductor 7 that rises along with the welding is set to a softening resistance distance Dh that is a length that does not reach the softening resistance temperature of the insulating coating 7h. Accordingly, the peeling length Lp (Lp2) of the insulating coating 7h is set. In the present embodiment, in the case of laser welding using the conductive plate 10, the separation length Lp is not set, so the softening resistance distance Dh is shortened by “ΔDh” corresponding to the separation length Lp.

  However, since there is a thickness of the conductive plate 10 (for example, about 1 [mm]), in the case of laser welding using the conductive plate 10, the segment conductor 7 protrudes by the thickness of the plate at the conductor end 7t. Therefore, the length of the conductor end portion 7t is substantially shortened by “TL1” which is shorter than “ΔDh” as compared with the case of TIG welding. In addition, as described above, in the case of laser welding, the stretching amount “Mu” does not occur. Therefore, the length of the conductor end portion 7t after welding is “TL2 = TL1 + Mu” as compared with the case where TIG welding is performed. Only shortened. Since the length of the conductor end 7t affects the length of the coil end, when laser welding using the conductive plate 10 is used, the coil end becomes shorter than when TIG welding is used, 3 can be reduced in size.

  By the way, even when laser welding is used in which the temperature rise of the segment conductor 7 is smaller than that of TIG welding, the amount of energy increases and the temperature rise increases as the laser irradiation time increases. Therefore, it is preferable that pulse irradiation is performed in the laser irradiation step # 20 in order to melt a necessary region while suppressing a temperature rise. Specifically, as illustrated in FIG. 7, an irradiation phase PE for irradiating a laser for a predetermined specified irradiation time, and a stop phase PP for stopping a laser irradiation for a predetermined stop time; The laser is irradiated by pulse irradiation that repeats. The specified irradiation time is such that the temperature of the segment conductor 7 (film tip temperature) at the boundary between the bare conductor end 7n and the insulating coating 7h does not melt the insulating coating 7h even if laser irradiation is continued. It is preferable that the time is set. The temperature at which the insulating coating 7h does not melt is preferably not the temperature at which the insulating coating 7h completely melts, but the softening temperature at which the appearance of the insulating coating 7h softens and changes its appearance.

  In the example shown in FIG. 7, three irradiation phases PE are provided. Since it is necessary to melt the segment conductor 7 through a plurality of irradiation phases PE, naturally, in the rest phase PP after the irradiation phase PE, the temperature does not decrease to the temperature before the start of the irradiation phase PE. Therefore, if the prescribed irradiation time of each irradiation phase PE is the same, the coating tip temperature in the irradiation phase PE executed later becomes higher. That is, the coating tip temperature is higher in the second irradiation phase PE2 than in the first irradiation phase PE1 in FIG. 7, and the coating tip temperature is higher in the third irradiation phase PE3 than in the second irradiation phase PE2. Therefore, the specified irradiation time is a time in a range in which the coating tip mobility does not reach the melting point or softening resistance temperature of the insulating coating 7h in the final irradiation phase PE (third irradiation phase PE3 in the embodiment illustrated in FIG. 7). Preferably it is set.

  In FIG. 7, three irradiation phases PE are set, but the prescribed irradiation time in each irradiation phase PE may be the same or may be a separate value. Similarly, the pause times in the two pause phases PP may be the same or may be different values. Further, the specified irradiation time and the resting time may be the same length or different lengths. Needless to say, the number of irradiation phases PE is not limited to three, and may be performed five times, for example. Moreover, if the temperature rise is within the range of the softening temperature of the insulating coating 7h, pulse irradiation may not be performed and welding may be performed by a single irradiation.

  According to experiments by the inventors, it has been confirmed that the conductive plate 10 and the segment conductor 7 are satisfactorily bonded by performing laser irradiation in a single mode as follows. That is, it is good when the laser output is 2500 [W], the focal spot diameter is 42 [μm], the specified irradiation time is 10 [ms], the pause time is 90 [ms], and the number of irradiation phases PE is 5 times. It has been confirmed that they are bonded to each other.

  By the way, the conductive plate 10 has a size that fits inside the arrangement area S of the two joining end faces 7p when viewed from the direction orthogonal to the reference plane Pr. Thus, it is not necessary to be substantially congruent with the arrangement region S. For example, as shown in FIG. 8, the conductive plate 10 may be smaller than the arrangement region S and may be similar to the arrangement region S. Further, the conductive plate 10 does not need to have a similar shape to the arrangement region S, and may have an elliptical shape, for example, as shown in FIG. As shown in these examples, when the conductive plate 10 smaller than the arrangement region S is used, the edge portion of the conductive plate 10 and the joining end surface 7p may be welded.

  The present invention can be used to form a coil of a rotating electrical machine by using a plurality of segment conductors and joining ends of different segment conductors.

3: Coil 5: Circumferential connection (segment conductor)
7: Segment conductor 7a: Basic segment conductor (segment conductor)
7h: Insulating coating 7p: End surface 7t for bonding: Conductor end 10: Conductive plate 10b: Irradiation surface 10t: Contact surface 90: Connection member (segment conductor)
H: Area corresponding to one joining end face on the irradiated surface PE: Irradiation phase PP: Rest phase Po: Opposing surface Pr: Reference plane S: Arrangement area # 10 of two joining end faces: Conductor holding step # 15: Plate Installation process # 20: Laser irradiation process

Claims (7)

In order to form a coil of a rotating electrical machine using a plurality of segment conductors coated with an insulating coating around the conductor extending direction, the rotating electrical machine of the rotating electrical machine that joins the end portions of the different segment conductors to each other A conductor joining method,
The two segment conductors that are conductors to be joined are in a state in which the opposing surfaces of the conductor end portions are adjacent to each other and the end surfaces for joining, which are the tip surfaces of the conductor end portions, are aligned along a reference plane. A conductor holding step for holding;
A plate installation step of installing a plate-like conductive plate so as to come into contact with both of the two end faces for joining of the segment conductors to be joined conductors;
The conductive plate and each of the two end surfaces for joining are irradiated by irradiating the irradiated surface with laser from the side of the irradiated surface, which is the surface opposite to the contact surface where the conductive plate contacts the end surface for joining. A laser irradiation process for welding
A method for joining conductors of a rotating electrical machine.   2. The method of joining a rotating electric machine according to claim 1, wherein the conductive plate has a size that fits inside an arrangement region of the two joining end faces when viewed from a direction orthogonal to the reference plane.   The conductor joining method for a rotating electrical machine according to claim 1 or 2, wherein, in the laser irradiation step, the laser is irradiated to a plurality of locations in a region corresponding to one joining end face on the irradiation surface.   In the laser irradiation step, the laser is irradiated by pulse irradiation that repeats an irradiation phase for irradiating the laser for a predetermined specified irradiation time and a pause phase for stopping the laser irradiation for a predetermined stop time. The conductor joining method for a rotating electrical machine according to any one of claims 1 to 3.   5. The conductor joining method for a rotating electrical machine according to claim 4, wherein the specified irradiation time is set to be less than a time during which the temperature of the segment conductor that rises with laser irradiation reaches the softening resistance temperature of the insulating coating. A coil of a rotating electrical machine formed by joining a plurality of segment conductors coated with an insulating coating around the conductor extending direction, and joining the conductor ends that are the ends of the different segment conductors,
The two segment conductors to be joined conductors are opposed to each other with the opposing faces of the conductor ends adjacent to each other, and the joining end faces that are the tip faces of the conductor ends are aligned along a reference plane And having a plate-like conductive plate installed so as to come into contact with both of the two end faces for joining of the segment conductors to be the conductors to be joined,
Each of the conductive plate and the two end surfaces for bonding is irradiated by a laser irradiated on the irradiated surface from the side of the irradiated surface that is the surface opposite to the surface in contact with the bonding end surface. And a coil of a rotating electrical machine that is welded.   The coil for a rotating electrical machine according to claim 6, wherein the conductive plate has a size that fits inside two arrangement regions of the joining end faces when viewed from a direction orthogonal to the reference plane.

Images