Rotary electric machine stator

Abstract

To provide a rotary electric machine stator in which a plurality of approximately U-shaped conductor segments SC1, SC2 are connected via a hollow tube within a slot SL and a single coil Co is wound around the teeth St of a stator core, and by appropriately allocating the engagement length of the ends SS1, SS2 of the two conductor segments in the hollow tube JT, the variation in electrical resistance between the connected conductor segments and the effect on connection strength are reduced.SOLUTION: In a rotary electric machine stator, the tips of opposing wire segments in slots between the stator teeth are each inserted into a conductive hollow tube, and the plurality of wire segments are electrically connected, and the insertion length L1 of the tip of the wire segment inserted into one end of the hollow tube before being inserted into the slot is longer than the insertion length L2 of the tip of the wire segment inserted into the other end of the hollow tube.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a stator for a rotating electric machine, and more particularly to a stator in which a coil formed by connecting a plurality of conductor segments is wound on the teeth (stator teeth) of a stator core. [Background technology]

[0002] As a method for winding a coil around the teeth of a stator core of a rotating electric machine, a method is adopted in which both ends of a plurality of substantially U-shaped conductor segments are inserted into slots between the stator teeth from both sides in the central axis direction of the stator, and the ends of the opposing conductor segments are sequentially connected to each other in the slots, so that a single coil is wound around the stator teeth. In this method, various configurations have been proposed in particular for connecting the ends of opposing conductor segments without using a troublesome welding process or the like. For example, Patent Document 1 proposes a configuration in which the end of one conductor segment is formed into a concave shape and the end of the other conductor segment is formed into a convex shape, and the two are meshed to connect the conductor segments. Patent Documents 2 and 3 propose a configuration in which the ends of opposing conductor segments formed into a convex shape are pressed into both ends of a tubular fitting recess to connect them to each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2020-129879 [Patent Document 2] Patent Publication No. 2020-89119 [Patent Document 3] Patent Publication No. 2022-3859 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a configuration in which a single coil wound around a stator tooth is formed by fitting the convex tips of the conductor segments into the inside of both ends of a tubular member (hereinafter referred to as a "hollow tube") to connect a plurality of conductor segments, as in Patent Documents 2 and 3, typically, one end of the hollow tube is first fitted into one tip of the conductor segments to be connected to each other. Then, the end of the substantially U-shaped conductor segment fitted into the hollow tube is inserted into the slot between the stator teeth from one side in the axial direction of the stator core, and the end of the other conductor segment is inserted from the other side in the axial direction of the stator core. In this state, a pressing force is applied from both sides in the axial direction of the stator core in a direction in which the connected conductor segments approach each other, and the tip of one conductor segment is pressed into the other end of the hollow tube fitted into the tip of the other conductor segment, thus connecting the two conductor segments (see FIG. 2).

[0005] Regarding the above-mentioned configuration of connecting conductor segments using a hollow tube, the inventors of the present invention have found that the variation in electrical resistance between the connected conductor segments and the connection strength are affected by how the ends of the two conductor segments are inserted into the hollow tube or how the insertion length of the ends of the two conductor segments into the hollow tube is allocated. More specifically, if the insertion length of the end of one conductor segment into which the hollow tube is first fitted is too short, when the conductor segment is pressed in the slot to press the end of the other conductor segment into the other end of the hollow tube, the hollow tube may slide and shift on the end of one conductor segment, so that the end of the other conductor segment to be pressed in may not be fully inserted into the end of the hollow tube, which may cause an increase or variation in electrical resistance between the conductor segments and a decrease in connection strength.

[0006] In consideration of the above circumstances, the main object of the present invention is to, in a stator of a rotating electric machine in which a plurality of conductor segments are connected via hollow tubes within slots to form a single coil wound around the teeth of a stator core, by appropriately allocating the fitting length of the ends of the two conductor segments in the hollow tube, thereby minimizing the variation in electrical resistance between the connected conductor segments and the impact on the connection strength. [Means for solving the problem]

[0007] According to the present invention, the above-mentioned object is achieved by a stator for a rotating electric machine, comprising a stator core having a coil wound around a stator tooth protruding radially inward, the coil being formed by connecting a plurality of approximately U-shaped conductor segments in a single line, both ends of the plurality of conductor segments being inserted into slots between the stator teeth from both axial sides of the stator core, tips of the opposing conductor segments being fitted into either of both ends of a conductive hollow tube, the plurality of conductor segments being electrically connected, and the length of insertion of the tip of the conductor segment fitted into one end of the hollow tube before being inserted into the slot is longer than the length of insertion of the tip of the conductor segment fitted into the other end of the hollow tube.

[0008] In the above configuration, the "rotating electric machine" may be any type of rotating electric machine (generator, electric motor, motor-generator) that uses a stator wound with a coil. In the present invention, the "coil" is, as described above, a plurality of conductor segments, i.e., a wire made of a conductive material (copper, aluminum, etc.) that is connected in sequence to form a single helix. Note that a plurality of coils may be wound on the above stator core, and in that case, each coil is formed by connecting a plurality of conductor segments in a single helix (i.e., the stator of the present invention also includes a case where a plurality of coils are wound on the stator core). The hollow tube is a tubular member that may be made of a conductive material similar to that of the conductor segments. The stator core on which the stator teeth protruding radially inward are formed may be a normal stator core. The coil may be wound on the stator teeth in any manner. The conductor segments are covered with an insulating coating except for the tip that is inserted into the hollow tube, so that adjacent conductor segments do not become conductive even if they come into contact with each other. The outer surface of the hollow tube is also covered with an insulating coating. The inside of the hollow tube and the tip portion of the conductor segment that enters the end of the hollow tube have no insulating coating or have been removed, making them conductive, so that the two conductor segments become conductive when connected by the hollow tube.

[0009] In the stator of the rotating electric machine of the present invention, as described above, both ends of the multiple wire segments (both branches of the approximately U-shape) are inserted into the slots from both axial sides of the stator core, and the tips of the opposing wire segments are fitted into either one of the two ends of the conductive hollow tube, thereby forming a coil in which the multiple approximately U-shaped wire segments are connected together. In particular, in the present invention, the insertion length of the tip of the wire segment fitted into one end of the hollow tube before being inserted into the slot is configured to be longer than the insertion length of the tip of the wire segment fitted into the other end of the hollow tube. In this configuration, since the insertion length of the tip of the conductor segment that is first inserted into the hollow tube is long, the contact area between the hollow tube and the tip of the conductor segment that is first inserted into the hollow tube is large (frictional resistance is large), so that even when the tip of another conductor segment is pressed against the other end of the hollow tube, the hollow tube is less likely to shift in the pressing direction of the tip of the conductor segment that is first inserted into the hollow tube, and the position of the hollow tube is maintained, so that the tip of the conductor segment can be inserted more reliably into the other end of the hollow tube, thereby avoiding an increase in electrical resistance between the conductor segments and a decrease in connection strength (due to incomplete connection of the tips of the conductor segments). Also, as will be shown in the section on embodiments later, when the insertion length of one tip of a hollow tube is longer than that of the other, there is an advantage that the electrical resistance is reduced.

[0010] In the above configuration, it is preferable that only the tip of each conductor segment is formed to have a smaller diameter than the conductor segment body, and the diameter is enlarged (enlarged diameter portion) from a portion a certain length away from the tip surface, which may be set appropriately, so that the insertion length into the hollow tube is not excessively long. In this case, the displacement of the hollow tube is stopped at the portion where the diameter is enlarged near the tip of the conductor segment. In this regard, the tip of the conductor segment that is inserted into one end of the hollow tube before being inserted into the slot may be inserted into the hollow tube until the end of the hollow tube abuts against the portion where the diameter is enlarged near the tip of the conductor segment. This makes it possible to more reliably prevent the position of the hollow tube from being displaced when the tip of the other conductor segment is pressed into the other end of the hollow tube.

[0011] In the above configuration, when the tips of the conductor segments from both ends come into contact with each other in the hollow tube, the electrical resistance is significantly reduced (compared to when the tips are not in contact). However, as already mentioned, when the conductor segments are pressed from both sides of the stator core, some deformation of the conductor segments in the direction of contraction in the axial direction of the stator core is unavoidable, and the degree of deformation varies, which causes variations in the length of the insertion of the tips of the conductor segments into the hollow tube, making it difficult to make the tips of the conductor segments come into contact with each other at all of the joints of the many conductor segments (doing so is undesirable because it may cause the conductor segments to deform excessively). Therefore, in the present invention, it is preferable that the tips of the conductor segments from the ends of the hollow tube are inserted into the ends of the hollow tube in any case so that there is a gap. This reduces the variation in electrical resistance. Effect of the Invention

[0012] Thus, according to the configuration of the present invention, it is expected that variations in electrical resistance and reduction in connection strength at the connection portions of the multiple conductor segments that form the coils can be avoided. In a typical rotating electric machine, a three-phase coil is wound in the stator, but according to the configuration of the present invention, when the conductor segments are pressed to connect them, the hollow tube is prevented from shifting at the tip of the conductor segment that is inserted into one end of the hollow tube before being inserted into the slot, and therefore it is expected that variations in the configuration of the connection portions of the conductor segments can be reduced, so that the electrical resistances and connection strengths of all the three-phase coils become uniform, and thus the stability of the operation of the rotating electric machine is expected to be improved.

[0013] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a coil formed by connecting a plurality of conductor segments wound around stator teeth in the stator of this embodiment. The left side shows the coil before connection, and the right side shows the coil after connection. [Diagram 2] Fig. 2(A) is a schematic diagram of the vicinity of the tip of a conductor segment, the tip of which is inserted into a hollow tube before being inserted into a slot in this embodiment, and Figs. 2(B) and (C) are schematic diagrams of the present embodiment before and after the tips of opposing conductor segments are joined in a slot, respectively. [Diagram 3] Fig. 3(A) is a schematic diagram showing the state of the tips of opposing conductor segments connected according to the teachings of this embodiment. Fig. 3(B) is a schematic diagram showing a case where the tips of opposing conductor segments are inserted into a hollow tube to approximately the same length without following the teachings of this embodiment. Fig. 3(C) is a schematic diagram showing a case where the tips of opposing conductor segments are in contact without following the teachings of this embodiment. [Figure 4]Figures 4(A) and (B) are schematic diagrams respectively before and after connecting the ends of opposing wire segments within a slot, when the ends of the wire segments inserted into the hollow tube before being inserted into the slot are short. [Explanation of symbols]

[0015] Co... coil, SC... wire segment, St... stator tooth, M... face plate, P... pressing force, SS... wire segment tip, JT... hollow tube, DS... wire segment expansion, SL... slot, sp... tip gap BEST MODE FOR CARRYING OUT THEINVENTION

[0016] The present invention will now be described in detail with reference to some preferred embodiments thereof with reference to the accompanying drawings, in which like reference numerals indicate like parts.

[0017] Overview of coils wound around stator teeth In the stator of the rotating electric machine of this embodiment, as in the cases of Patent Documents 2 and 3, the coil wound around the teeth protruding inward in the radial direction of the annular stator core is a coil formed by sequentially connecting a plurality of conductor segments made of a conductive material in a spiral shape. More specifically, as shown in FIG. 1, in this embodiment, a plurality of substantially U-shaped conductor segments SC are arranged from both sides of the axial direction of the stator core so that their ends face each other and surround the stator teeth St (left figure), and then the central parts of the conductor segments SC are pressed toward each other by a pressing force P from a face plate M, and as shown in the right figure, the ends of the conductor segments SC are sequentially connected to the ends of the opposing conductor segments SC, and the conductor segments are wound around the stator teeth St as a single coil Co. The winding manner of the coil around the stator teeth may be any (concentrated winding, distributed winding, etc.).

[0018] The conductor segment SC is formed by appropriately bending or curving a wire made of a conductive material such as copper or aluminum into a U-shape, and its surface, except for the tip, is covered with an insulating coating. The cross section of the conductor segment may be, for example, a rectangle of 3 mm x 2 mm or 3 mm x 4 mm, and the length is, for example, 100 to 150 mm, but is not limited thereto.

[0019] Connecting the ends of wire segments As described above, when connecting the tips of a plurality of conductor segments in sequence, in this embodiment, as shown in FIG. 2, the tips SS1, SS2 of the opposing conductor segments SC1, SC2 are connected using a tubular member (hollow tube) JT with both ends open, as in the cases of Patent Documents 2 and 3. The hollow tube JT may be a tubular member made of the same conductive material as the conductor segments. When connecting the tips of the conductor segments using such a hollow tube JT, more specifically, first, before inserting the conductor segments into the slots SL between the stator teeth St, as shown in FIG. 2(A), the hollow tube JT is fitted onto the tip SS1 of one of the conductor segments SC1. The tip SS1 may be formed to have a diameter smaller than the diameter of the entire conductor segment SC1, as shown in the figure. In addition, the hollow tube JT is formed so that its inner diameter is smaller than the outer diameter of the tip SS1 of the conductor segment SC1, and pressure is applied on the tip SS1 in a direction that expands the diameter of the hollow tube JT, thereby restricting movement of the hollow tube JT in its length direction on the tip SS1. Thereafter, as shown in Fig. 2(B), the tip SS1 of the conductor segment SC1 fitted in the hollow tube JT enters from one side (the lower side in the figure) of the slot SL, and the tip SS2 of the other conductor segment SC2 enters from the other side (the upper side in the figure) of the slot SL, and with the tip SS2 aligned with the open end of the hollow tube JT, a pressing force P is applied to the conductor segments SC1 and SC2 toward each other, whereby the tip SS2 of the conductor segment SC2 is pressed into the end of the hollow tube JT, and the conductor segments SC1 and SC2 are connected. Here, as shown in the figure, the tip SS2 may also be formed to have a diameter smaller than the diameter of the entire conductor segment SC2, and the tip SS2 is formed to be larger than the inner diameter of the hollow tube JT so that the hollow tube JT is more securely held on the tip SS2. Note that the tip SS1 of the conductor segment SC1, the tip SS2 of the conductor segment SC2, and the inner surface of the hollow tube JT each have no insulating coating and the conductive material is exposed, so that the conductor segments SC1 and SC2 are electrically conductive.

[0020] Regarding the connection of the tips of the conductor segments using the above-mentioned hollow tube, according to research and development by the inventors of this embodiment, it has been found that if the fitting lengths in the hollow tube are allocated so that the fitting length L1 in the hollow tube JT of the tip SS1 of the conductor segment SC1, which is first fitted into the hollow tube JT before insertion into the slot SL, is longer than the fitting length L2 in the hollow tube JT of the tip SS2 of the conductor segment SC2, which is later fitted into the hollow tube JT inside the slot SL, as shown in Figures 2 and 3(A), then when the opposing conductor segments are pressed toward each other, the tip SS2 of the conductor segment SC2 can be more reliably pressed into the end of the hollow tube JT, thereby more reliably connecting the tip SS1 of the conductor segment SC1 and the tip SS2 of the conductor segment SC2.

[0021] More specifically, for example, as shown in FIG. 4(A), when the fitting length in the hollow tube JT of the tip SS1 of the conductor segment SC1, which is first inserted into the hollow tube JT before insertion into the slot SL, is insufficient, i.e., when the fitting length in the hollow tube JT of the tip SS1 of the conductor segment SC1, which is first inserted into the hollow tube JT, is equal to or shorter than the fitting length in the hollow tube JT of the tip SS2 of the conductor segment SC2, which is inserted into the hollow tube JT later, then when the conductor segments SC1, SC2 are pressed toward each other, the hollow tube JT will slide and shift on the tip SS1 of the conductor segment SC1, as shown in FIG. 4(B). As a result, the tip SS2 of the conductor segment SC2 will hardly insert into the end of the hollow tube JT, and the connection between the conductor segments SC1, SC2 will be incomplete. In particular, as described in relation to Figure 1, when the central portions of the U-shaped conductor segments SC1, SC2 are pressed toward each other in the axial direction of the stator by the face plate M, the pressing force is considerable (the load between a pair of ends can be 100 to 200 N), and it is inevitable that the entire conductor segments SC1, SC2 will deform to a certain extent in the compression direction. Therefore, the proximity distance between the ends SS1, SS2 of the conductor segments SC1, SC2 is smaller than the proximity distance between the opposing face plates M (for example, even if the face plates M shrink by 1 mm, the shrinkage of the ends SS1, SS2 does not reach that amount), and the insertion length of the ends in the hollow tube JT may not be as long as expected from the proximity distance between the face plates M. In this case, when the hollow tube JT is in a state in which it easily slides over the tip SS1 of the conductor segment SC1, it becomes difficult to determine whether the tip SS2 of the conductor segment SC2 is securely pressed into the end of the hollow tube JT.

[0022] 2 or 3(A), if the hollow tube JT is fitted onto the tip SS1 of the conductor segment SC1 so that the fitting length L1 of the tip SS1 of the conductor segment SC1, which is fitted into the hollow tube JT first, is longer than the fitting length L2 of the tip SS2 of the conductor segment SC2, which is fitted into the hollow tube JT later, in the hollow tube JT, when the conductor segments SC1 and SC2 are pressed toward each other, the frictional resistance between the hollow tube JT and the tip SS1 is large, so that even if the hollow tube JT is pressed by the tip SS2, it is difficult for it to slide on the tip SS1, and therefore the tip SS2 is more reliably pressed into the hollow tube JT. In this regard, when the hollow tube JT is fitted onto the tip SS1 of the conductor segment SC1 first, it is preferable that the hollow tube JT be fitted so that its end abuts against the expanded diameter portion DS of the tip SS1 of the conductor segment SC1. In this case, when the hollow tube JT is pressed against the tip SS2, sliding on the tip SS1 is prevented by the enlarged diameter portion DS, the position of the hollow tube JT becomes more stable, and thus the tip SS2 is more reliably pressed into the hollow tube JT.

[0023] As described above, in the case where the tip SS2 is more reliably pressed into the hollow tube JT, it is expected that the connection strength of the conductor segments SC1 and SC2 is improved and that a decrease in electrical resistance due to insufficient connection is avoided. In this regard, according to a simulation by the inventors of the present invention, it was found that the electrical resistance between both ends when the insertion length L1 of one tip SS1 in the middle space JT is longer than the insertion length L2 of the other tip SS2, as shown in Figure 3(A), is lower than the case where the insertion length L1 of one tip SS1 in the middle space JT is equal to the insertion length L2 of the other tip SS2 (Figure 3(B)). Thus, it is expected that the electrical resistance can be reduced by increasing the insertion length of one tip, as in this embodiment.

[0024] In the above-mentioned connection of the tips of the conductor segments using a hollow tube, if the tips SS1 and SS2 of the conductor segments SC1 and SC2 are in direct contact as shown in Fig. 3(C), the electrical resistance is extremely reduced compared to when they are not in direct contact. In this regard, as already mentioned, when the conductor segments SC1 and SC2 are pressed in the direction of approaching each other, it is inevitable that the entire conductor segments SC1 and SC2 are deformed to a certain extent in the compression direction, and it is difficult to precisely control the approaching distance between the tips SS1 and SS2, and it is difficult to make the tips SS1 and SS2 directly contact each other at the connection parts of the tips of all the conductor segments (in that case, the degree of deformation of the conductor segments will be large, and other problems may occur). On the other hand, in a stator in which multiple coils are assembled, if the tips of the conductor segments of only some of the coils are in direct contact with each other, an imbalance in the electrical resistance between the coils will occur, which may affect the stability of the operation of the rotating electric machine. Therefore, in this embodiment, it is preferable to provide a gap sp between the ends of all of the conductor segments at their connecting portions, which is expected to improve the balance of electrical resistance between the coils and the stability of the operation of the rotating electric machine.

[0025] The above description has been given in relation to the embodiment of the present invention, but it will be apparent to those skilled in the art that many modifications and changes can be easily made thereto, and that the present invention is not limited to the embodiment exemplified above, but can be applied to various devices without departing from the concept of the present invention.

Claims

[Claim 1] A stator for a rotating electric machine, comprising a coil wound on stator teeth protruding radially inward from a stator core, the coil being formed by connecting a plurality of approximately U-shaped conductor segments in a single line, both ends of the plurality of conductor segments being inserted into slots between the stator teeth from both axial sides of the stator core, tips of the opposing conductor segments being fitted into either of both ends of a conductive hollow tube, the plurality of conductor segments being electrically connected, and the length of insertion of the tip of the conductor segment fitted into one end of the hollow tube before being inserted into the slot is longer than the length of insertion of the tip of the conductor segment fitted into the other end of the hollow tube.

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