JP7799990B2 - Flat wire motor coil and method of manufacturing flat wire motor coil - Google Patents

Description

The present invention relates to a rectangular wire motor coil.

Patent Document 1 discloses a bending device used in the manufacture of a stator containing multiple coils. In the tip bending process using the bending device, the tip ends of the segment coils to be joined are brought into contact with each other in a state where they extend generally parallel to each other due to the springback of the legs.

Japanese Patent Application Laid-Open No. 2019-140822

In rotating electrical machines equipped with flat wire motor coils, extending the tips of joined flat wires in the axial direction increases the overall length. For this reason, one approach to reducing the overall length is to bend the tips so that they butt against each other. However, after bending, the tips that are butted against each other can move away from each other due to springback, causing misalignment. As a result, welding after bending can be inappropriate, or can be difficult due to clearances between the tips.

The present invention was made in consideration of these issues, and aims to appropriately position each of the tip portions that are joined together.

A flat wire motor coil according to one embodiment of the present invention has a first tip portion and a second tip portion that are welded after being aligned by bending. When the first tip portion and the second tip portion are aligned in the extension direction of the first tip portion and the second tip portion by bending , the tips of the first tip portion and the second tip portion in the extension direction butt and engage with each other , and have a tip shape that maintains the engagement state of the first tip portion and the second tip portion against springback that separates the first tip portion and the second tip portion.

According to another aspect of the present invention, there is provided a method for manufacturing a flat wire motor coil having a first tip and a second tip that are welded after being aligned with each other by bending, wherein the first tip and the second tip are aligned with each other in the extension direction of the first tip and the second tip by bending in the process , and the tips in the extension direction of the first tip and the second tip are butted together and engaged with each other , and have a tip shape that maintains the engagement state of the first tip and the second tip against springback that separates the first tip and the second tip, and a method for manufacturing a flat wire motor coil is provided, wherein the tip shape maintains the engagement state of the first tip and the second tip when welding.

According to these aspects, the tip shape holds the first tip portion and the second tip portion in an engaged state with their tips butted against each other when bending is performed. This allows the first tip portion and the second tip portion to be joined to each other to be properly positioned. Furthermore, the tip shape allows the first tip portion and the second tip portion to be held in engaged state during welding. This allows the first tip portion and the second tip portion to be joined to each other to be properly positioned throughout welding, even without the need for complex clamping fixtures or the like to maintain the engaged state after bending.

FIG. 2 is a schematic diagram showing the configuration of a main part of a stator. FIG. 2 is a plan view showing a main part of the stator. 1 is a diagram showing the first and second tip portions of the flat wire motor coil in an engaged state. FIG. 4A and 4B are explanatory diagrams of a first tip shape and a second tip shape. FIG. 2 is a diagram showing the first step of the manufacturing process of the stator coil. FIG. 10 is a diagram showing a second step in the manufacturing process of the stator coil. FIG. 10 is a diagram showing a second step in the manufacturing process of the stator coil. FIG. 10 is a diagram showing a third step in the manufacturing process of the stator coil. FIG. 10 is a diagram showing a fourth step in the manufacturing process of the stator coil. FIG. 10 is an explanatory view showing the welding of the first tip portion and the second tip portion. FIG. 10 is an explanatory diagram of welding in the case of a comparative example. FIG. 10 is a diagram showing a main part of a stator coil according to a first modified example. FIG. 10 is a diagram showing a modification of the first modification; FIG. 10 is a diagram showing a main part of a stator coil according to a second modified example. FIG. 10 is an explanatory diagram of a bending process in a second modified example. FIG. 10 is a diagram showing a main part of a stator coil according to a third modified example. 10A and 10B are explanatory diagrams of a bending process in a third modified example. FIG. 10 is a diagram showing a main part of a stator coil according to a fourth modified example. 10A and 10B are explanatory diagrams of bending processing in a fourth modified example. FIG. 10 is a diagram showing a first comparative example of a joint portion. FIG. 1 is a first diagram showing a second comparative example of a joint portion. FIG. 2 is a second diagram showing a second comparative example of a joint portion. FIG. 10 is a first explanatory diagram of welding in a second comparative example. FIG. 10 is a second explanatory diagram of welding in the second comparative example.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Figure 1 is an external view showing the main parts of stator 100. Figure 2 is a plan view showing the main parts of stator 100. Figure 2 schematically shows stator coil 1 in a ring shape. Stator 100 is used, for example, in rotating electric machines that constitute drive sources or generators in electric vehicles and hybrid vehicles. Stator 100 includes stator coil 1, stator core 2, and mold 3. Stator coil 1 is a rectangular wire motor coil made of rectangular wire W with a rectangular cross section, and is made of, for example, copper. Stator coil 1 includes U-phase, V-phase, and W-phase stator coils. Stator core 2 is ring-shaped and is provided with teeth TH. The teeth TH protrude radially inward and are provided in multiple numbers along the circumferential direction. Slots ST are formed between adjacent teeth TH. Both ends of multiple rectangular wires W are inserted into the multiple slots ST from below in Figure 1. Each of the multiple rectangular wires W has a U-shape. Each of the multiple flat wires W may be I-shaped, i.e., straight. Each of the multiple flat wires W is insulated, for example with an enamel coating, and the insulating coating on both ends of each flat wire W is removed before assembly into the stator 100. The tips of different flat wires W are joined in a predetermined combination to form the U-, V-, and W-phase stator coils. The joints between the flat wires W protrude from one end surface of the stator core 2 to form the coil end E. A ring-shaped mold 3 is provided on the coil end E.

The joints between flat wires W may be arranged as follows. Figure 19 shows a first comparative example of the joint. Figures 20A and 20B show a second comparative example of the joint. Figures 21A and 21B are explanatory diagrams of welding in the second comparative example. Figure 20A shows multiple aligned joints, while Figure 20B shows a single joint. Figures 21A and 21B show a top view along with a side view. The solid lines indicate one side of the flat wires W to be joined together, and the dashed lines indicate the other side of the flat wires W to be joined together.

In the first comparative example shown in Figure 19, the total length of the rotating electric machine is extended by the amount by which the tips of the joined flat wires W extend in the axial direction of the rotating electric machine (the vertical direction in Figure 19), i.e., the axial length L of the joint. Therefore, as shown in Figures 20A and 20B, it is conceivable to reduce the total length by bending the tips of the joined flat wires W so that their tips are butted together. In this case, as shown in Figure 21A, welding can be performed by irradiating laser light B from a laser irradiation device L onto the tips of the flat wires W, which remain butted together during welding. However, as shown in Figure 21B, the tips that are butted together by bending become free after bending. Therefore, the tips may move away from each other due to springback after bending, causing misalignment. As a result, there is a concern that welding after bending may be inappropriate or difficult due to clearance between the tips. In consideration of these circumstances, in this embodiment, the stator coil 1 is configured as follows.

Figure 3 shows the first tip portion 10 and the second tip portion 20 in an engaged state. The first tip portion 10 and the second tip portion 20 are one and the other of the flat wires W that are joined to each other among the multiple flat wires W that make up the stator coil 1. The first tip portion 10 and the second tip portion 20 are aligned to each other by bending and then joined by welding. The first tip portion 10 and the second tip portion 20 are butted together and engaged when aligned to each other by bending. The first tip portion 10 and the second tip portion 20 have a tip shape S. The tip shape S maintains the engaged state of the first tip portion 10 and the second tip portion 20, which are butted together and engaged to each other. The tip shape S has a first tip shape S1 formed on the first tip portion 10 and a second tip shape S2 formed on the second tip portion 20. The first tip shape S1 is concave and forms a recess R. The second tip shape S2 is convex and forms a protrusion P. The tip shape S is set within a range that allows the convex portion P and concave portion R to engage through bending, including cases where deformation is involved. Deformation includes elastic deformation and plastic deformation.

Figure 4 is an explanatory diagram of the tip shape S. The front side is the side to which force is applied during bending, and the back side is the opposite side. The front side is also the side to which laser light B is irradiated during welding. The first tip 10 has a front-side protrusion 11 and a back-side protrusion 12. The front-side protrusion 11 is formed on the front side of the first tip 10 and has a protrusion length r1. The back-side protrusion 12 is formed on the back side of the first tip 10 and has a protrusion length r2. The protrusion lengths r1 and r2 are protrusion lengths from the bottom of the recess R along the extension direction of the first tip 10, and the protrusion length r2 is set longer than the protrusion length r1. Therefore, the back-side protrusion 12 protrudes more than the front-side protrusion 11. The front-side protrusion 11 allows the protrusion P to enter the recess R during bending. The back-side protrusion 12 receives and slides against the protrusion P during bending. The rear protrusion 12 protrudes further than the front protrusion 11, and therefore also functions as a support for the laser beam B.

The second tip portion 20 has a front-side notch portion 21 and a back-side notch portion 22. The front-side notch portion 21 is formed on the front side of the second tip portion 20 and has a notch length p1. The back-side notch portion 22 is formed on the back side of the second tip portion 20 and has a notch length p2. Notch lengths p1 and p2 are notch lengths from the tip of the protrusion P along the extension direction of the second tip portion 20, and notch length p2 is set longer than notch length p1. The shape of the front-side notch portion 21 is adjusted to match the front-side protrusion 11. This ensures space for the front-side protrusion 11 to be positioned during bending. The front-side notch portion 21 maintains a slight gap between itself and the front-side protrusion 11 when the protrusion P and the recess R are engaged. The back-side notch portion 22 has a partially cylindrical curved surface that is convex toward the back side at the portion forming the protrusion P. This makes it easier for the convex portion P to slide into the concave portion R during bending. The rear cutout portion 22 forms a space in which the rear protrusion 12 is positioned during bending.

Figures 5 to 8 show the manufacturing process for the stator coil 1. In the first step shown in Figure 5, a flat wire W wound on a spool is straightened, the insulating coating is removed from the end of the straightened flat wire W, and the flat wire W is cut to the desired length. The insulating coating is also removed from the end of the flat wire W newly formed by cutting. In the second step shown in Figures 6A and 6B, a first tip shape S1 and a second tip shape S2 are formed at both ends of the flat wire W by shearing. The tip formed with the first tip shape S1 constitutes the first tip portion 10, and the tip formed with the second tip shape S2 constitutes the second tip portion 20. The second step may further include a molding process such as press molding. In the third step shown in Figure 7, each flat wire W is bent into a U-shape and inserted into the stator core 2, and then bent so that the first tip portion 10 and the second tip portion 20 are ready for bending. In the standby position, the first tip portion 10 and the second tip portion 20 are arranged so that their tips face each other and are convex on the front side. Furthermore, when viewed along the axial direction of the stator 100 (the up-and-down direction in FIG. 7), the first tip portion 10 and the second tip portion 20 are arranged so that they are separated on the front side and overlap on the back side. In the standby position, the first tip portion 10 and the second tip portion 20 can be abutted against each other on the back side.

In the fourth step shown in Figure 8, bending is performed as described below. That is, as shown in Figure 1 of Figure 8, a force is applied from the front side during bending, and the first tip portion 10 and the second tip portion 20 are pushed toward the back side in response. Then, the first tip portion 10 and the second tip portion 20 gradually approach each other while abutting on the back side, and the protrusion P gradually slides into the recess R in response. As a result, the protrusion P and the recess R engage as shown in Figure 2. As shown in Figure 3, the first tip portion 10 and the second tip portion 20 continue to be pushed slightly beyond the desired position, and the bending force is then removed. As a result, the first tip portion 10 and the second tip portion 20 attempt to return slightly due to springback. However, at this time, the engagement state of the first tip portion 10 and the second tip portion 20 is maintained by the tip shape S. Therefore, as shown in Figure 4, the first tip portion 10 and the second tip portion 20 do not attempt to continue to separate further and remain engaged. After the bending process is complete, the stator 100 is transferred to the welding process while the first tip portion 10 and the second tip portion 20 remain engaged, and the first tip portion 10 and the second tip portion 20 are welded as described below.

Figure 9 is an explanatory diagram of welding the first tip portion 10 and the second tip portion 20. Figure 10 is an explanatory diagram of welding in a comparative example. The stator coil 1X in the comparative example has a first tip portion 10X instead of the first tip portion 10, and the first tip portion 10X has a back-side protrusion 12X instead of the back-side protrusion 12. As shown in Figure 9, during welding, the first tip portion 10 and the second tip portion 20 are held in an engaged state by the tip shape S. The laser irradiation device L irradiates the first tip portion 10 and the second tip portion 20 with laser light B while they are held in an engaged state. The laser light B is irradiated from the front side to the first tip portion 10 and the second tip portion 20. As a result, a molten zone M is formed around the irradiated laser light B in the first tip portion 10 and the second tip portion 20, and the first tip portion 10 and the second tip portion 20 are welded to each other.

In the comparative example, the rear-side protrusion 12X has the same protrusion length as the front-side protrusion 11 and does not protrude further than the front-side protrusion 11. Therefore, when laser light B is irradiated into the gap on the front side, the laser light B completely penetrates the engaged first tip 10 and second tip 20. As a result, spatter SP is generated on the rear side of the first tip 10 and second tip 20, and the penetrated laser light B may hit and damage the stator 100 during assembly.

In this embodiment, the rear projection 12 functions as a support for the irradiated laser beam B. Furthermore, to ensure proper welding, the laser beam B is irradiated at a position slightly offset toward the first tip portion 10 from the gap on the front side. The laser irradiation device L can detect the gap on the front side, for example, using a camera, and irradiate the laser beam B at this position. Furthermore, the welding parameters of the laser irradiation device L, such as the laser output, are set so that the laser beam B does not completely penetrate the first tip portion 10 and the second tip portion 20. Therefore, in this embodiment, the laser beam B does not penetrate the rear projection 12. This prevents spatter SP from occurring on the rear side of the first tip portion 10 and the second tip portion 20, and prevents the penetrated laser beam B from hitting components of the stator 100 during assembly, thereby damaging the stator 100.

Next, we will explain the main effects of this embodiment.

The stator coil 1 has a first tip portion 10 and a second tip portion 20 that are welded after being aligned by bending. The first tip portion 10 and the second tip portion 20 butt and engage with each other when aligned by bending, and have a tip shape S that maintains the engaged state of the first tip portion 10 and the second tip portion 20. With this configuration, the tip shape S holds the first tip portion 10 and the second tip portion 20 in an engaged state with their tips butted against each other when bending. This allows the first tip portion 10 and the second tip portion 20 to be joined together to be properly positioned. Furthermore, the tip shape S maintains the engaged state of the first tip portion 10 and the second tip portion 20 during welding. This allows the first tip portion 10 and the second tip portion 20 to be joined together to be properly positioned throughout the welding process, even without the need for complex clamping fixtures or other tools to maintain the engaged state after bending.

In this embodiment, the tip shape S forms a recess R and a protrusion P that engage with each other, with the recess R formed on the first tip portion 10 and the protrusion P formed on the second tip portion 20. The recess R has a front-side protrusion 11 that protrudes from the front side of the first tip portion 10 and a back-side protrusion 12 that protrudes from the front-side protrusion 11 on the back side of the first tip portion 10. With this configuration, the back-side protrusion 12 can receive and slide-guide the protrusion P during bending. In other words, bending from the front side allows the protrusion P to slide into the recess R. Furthermore, the back-side protrusion 12 can also function as a support for the laser beam B during welding. Therefore, even if the laser beam B is irradiated onto a gap on the front side, it is difficult for the laser beam B to penetrate the back-side protrusion 12. This makes it possible to set welding parameters to as appropriate values as possible while avoiding damage to the stator 100 due to penetration of the laser beam B.

(First Modification)
FIG. 11 is a diagram showing a main portion of a stator coil 1 according to a first modified example. FIG. 12 is a diagram showing a modification of the first modified example. In this example, the tip shape S further includes a hook portion H. The hook portion H is provided on the rear-side protrusion 12 of the first tip portion 10 and the rear-side notch 22 of the second tip portion 20 and engages with each other. The hook portion H includes a first hook portion H1 and a second hook portion H2. The first hook portion H1 is provided on the rear-side protrusion 12 and is constituted by a hook. The second hook portion H2 is provided on the rear-side notch 22 and is constituted by a hook groove. The first hook portion H1 is convex on the front side and is disposed at the tip of the rear-side protrusion 12. The second hook portion H2 is concave on the front side and is disposed at the base end of the convex portion P formed by the rear-side notch 22. According to the first modified example, during the bending process, engagement occurs not only through the concave shape of the recess R and the convex shape of the convex portion P but also through the hook portion H. This contributes to further suppressing the occurrence of separation between the first tip portion 10 and the second tip portion 20 due to springback after bending. Furthermore, some deformation is permissible during bending, and in the first modified example, the first tip portion 10 and the second tip portion 20 can be engaged while being accompanied by some deformation due to the bending force. In this case, because the bending force is stronger than the springback force, it becomes difficult to release the engaged state of the first tip portion 10 and the second tip portion 20 by reversing the change with the springback force. Therefore, the first modified example also contributes to further suppressing the occurrence of separation in this respect.

As shown in FIG. 12, the hook portion H may be provided on the front-side protrusion 11 of the first tip portion 10 and the front-side cutout 21 of the second tip portion 20. In this case, the first hook portion H1 is formed as a hook that is convex on the back side and is located at the tip of the front-side protrusion 11. The second hook portion H2 is formed as a hook groove that is concave on the back side and is located at the base end of the protrusion P formed by the front-side cutout 21. This configuration also helps to further prevent separation between the first tip portion 10 and the second tip portion 20, as in the case shown in FIG. 11.

(Second Modification)
FIG. 13 is a diagram showing essential parts of a stator coil 1 according to a second modified example. In this example, the recessed portion R and the protruding portion P have the following shapes, thereby forming the hook portion H as described below. That is, the recessed portion R has a cylindrical inner surface shape that extends from the rear-side protruding portion 12 toward the front-side protruding portion 11 until it curves back, forming the first hook portion H1. The protruding portion P has a cylindrical outer surface shape that extends from the rear-side notch portion 22 toward the front-side notch portion 21 until it curves back to the rear side, forming the second hook portion H2. The first hook portion H1 is formed by a hook, and the second hook portion H2 is formed by a hook groove. The hook portion H is composed of the first hook portion H1 and the second hook portion H2 formed in this way. The hook portion H can be set within a range in which the first hook portion H1 elastically deforms when the protruding portion P and the recessed portion R engage with each other through bending.

Figure 14 is an explanatory diagram of the bending process in the second modified example. The upper diagram in Figure 14 shows the state before bending, and the lower diagram shows the state after bending. During bending, each flat wire W is pressed from the front side to the back side, which brings the first tip portion 10 and the second tip portion 20 closer together and causes the convex portion P to slide into the concave portion R. The convex portion P then fits into the concave portion R, engaging the convex portion P and the concave portion R, and at this time the first hook portion H1 and the second hook portion H2 also engage. Like the first modified example, the second modified example, in which the hook portions H engage in this manner, also helps to further prevent separation of the first tip portion 10 and the second tip portion 20 due to springback after bending.

(Third Modification)
FIG. 15 is a diagram showing a main portion of a stator coil 1 according to a third modified example. FIG. 16 is an explanatory diagram of the bending process according to the third modified example. As shown in FIG. 15 , the protrusion P has a bent shape that bends toward the back of the second tip portion 20 in a direction from the base end toward the tip end before the bending process. In other words, the protrusion is bent toward the back in advance. Meanwhile, the recess R has a straight shape in a direction from the opening toward the bottom. As shown in FIG. 16 , the protrusion P is plastically deformed during the bending process to become straight and engage with the recess R. According to the third modified example, the protrusion P, which is plastically deformed by the bending process and engages with the recess R, serves to prevent the protrusion P from slipping out of the recess R. Therefore, even if the first tip portion 10 and the second tip portion 20, which are engaged with each other, attempt to separate due to springback, the engaged state of the first tip portion 10 and the second tip portion 20, can be maintained.

(Fourth Modification)
FIG. 17 shows a main portion of a stator coil 1 according to a fourth modified example. FIG. 18 is an explanatory diagram of the bending process according to the fourth modified example. In this example, the recess R has a bent shape that bends toward the rear of the first tip portion 10 in a direction from the opening side toward the bottom side. The protrusion P also has a bent shape that bends toward the rear of the second tip portion 20 in a direction from the base end toward the tip side. The recess R and protrusion P each have a straight shape on both sides in the extension direction of the rectangular wire W and a bent shape that bends toward the rear at the center. In this example, the protrusion P is inserted into the recess R while deforming appropriately during the bending process, and the protrusion P and the recess R engage with each other. According to the fourth modified example, the bent shapes of the protrusion P and the recess R engaged with each other by the bending process serve to prevent the protrusion P from coming off. Therefore, even if the engaged first tip portion 10 and the second tip portion 20 attempt to separate due to springback, the engagement state of the first tip portion 10 and the second tip portion 20 can be maintained.

The above describes embodiments of the present invention, but these embodiments merely illustrate some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

1. Stator coil (rectangular wire motor coil)
2 Stator core 10 First tip portion 11 Front side protrusion portion 12 Back side protrusion portion 20 Second tip portion 21 Front side cutout portion 22 Back side cutout portion H Hook portion H1 First hook portion (hook)
H2 Second hook part (hook groove)
P Convex portion R Concave portion S Tip shape S1 First tip shape S2 Second tip shape W Flat wire

Claims (7)

A flat wire motor coil having a first tip portion and a second tip portion which are aligned with each other by bending and then welded,
The first tip portion and the second tip portion have a tip shape that maintains the engagement state of the first tip portion and the second tip portion against springback that separates the first tip portion and the second tip portion, such that the tips in the extension direction of the first tip portion and the second tip portion butt against each other when aligned with each other in the extension direction of the first tip portion and the second tip portion by the bending process.
A flat wire motor coil characterized by: The flat wire motor coil according to claim 1,
The tip shape has a recess and a protrusion that engage with each other, and the recess is formed on the first tip and the protrusion is formed on the second tip,
The recess has a front-side protrusion that protrudes from a front side of the first tip portion, and a back-side protrusion that protrudes further than the front-side protrusion from a back side of the first tip portion.
A flat wire motor coil characterized by: The flat wire motor coil according to claim 2,
the protrusion has a front-side notch formed on the front side of the second tip end portion and a back-side notch formed on the back side of the second tip end portion, the back-side notch having a notch length from the tip end longer than the front-side notch portion,
The tip shape further has a hook portion that engages with the front-side protrusion and the front-side notch, or the back-side protrusion and the back-side notch.
A flat wire motor coil characterized by: The flat wire motor coil according to claim 3,
the recess has a cylindrical inner surface shape that extends from the rear-side protruding portion toward the front-side protruding portion to form a hook,
the protrusion has a cylindrical outer surface shape that extends from the rear cutout portion toward the front cutout portion until it wraps around the rear side, forming a hook groove that engages with the hook;
The hook portion is composed of the hook and the hook groove.
A flat wire motor coil characterized by: The flat wire motor coil according to claim 2,
the protrusion has a bent shape that is bent toward the back side of the second tip portion in a direction from the base end side toward the tip side before the bending process is performed.
A flat wire motor coil characterized by: The flat wire motor coil according to claim 5,
The recess has a bent shape that bends toward the back side of the first tip portion in a direction from the opening side toward the bottom side.
A flat wire motor coil characterized by: A method for manufacturing a flat wire motor coil having a first tip portion and a second tip portion that are welded after being aligned by bending,
The first tip portion and the second tip portion have a tip shape that maintains the engagement state of the first tip portion and the second tip portion against springback that separates the first tip portion and the second tip portion , and the first tip portion and the second tip portion are aligned with each other in the extension direction of the first tip portion and the second tip portion by the bending process in the step, and the first tip portion and the second tip portion are aligned with each other in the extension direction of the second tip portion by the bending process in the step, and the second tip portion and the first ... and the second tip portion are aligned with each other in the extension direction of the second tip portion by the bending process in the step, and the second tip portion and the first tip portion and the second tip portion are aligned with each other in the extension direction of the second tip portion by the bending process in the step, and the first tip portion and the second tip portion are aligned with each other in the extension direction of the second tip portion by the bending process in the step, and the second tip portion and the first tip portion and the second tip portion are aligned with each other in the extension direction of the second tip portion by the bending process in the step, and the second tip portion and the first tip portion and the second tip portion are aligned with each other in the extension direction of the second tip portion by the bending process in the step, and the second tip portion and the first tip portion and the second tip portion are aligned with each other in the extension direction of
During welding, the tip shape maintains the first tip portion and the second tip portion in an engaged state.
A method for manufacturing a flat wire motor coil.