JP7466419B2 - Rotating electric machine and method for manufacturing the same - Google Patents

Description

The present invention relates to a radial gap type rotating electric machine, a radial gap type rotating electric machine, and a method for manufacturing a rotating electric machine.

High efficiency is required for rotating electric machines used as power sources for industrial machinery and for driving automobiles. To increase the efficiency of a motor, it is necessary to reduce motor losses, and a common design method is to consider designs that reduce the two major causes of motor losses: coil copper loss and iron core iron loss.

Once the output characteristics (rotation speed and torque) of the motor's required specifications are determined, mechanical loss is uniquely determined, so it is important to design a motor that reduces iron loss and copper loss. Iron loss can be reduced by using soft magnetic materials.

In typical motors, magnetic steel sheets are used for the iron core, with different loss levels depending on the thickness and silicon content. Soft magnetic materials include high-performance materials such as iron-based amorphous metals, which have higher magnetic permeability and lower core loss than magnetic steel sheets, finemet, and nanocrystalline materials that promise high magnetic flux density. These material systems have many issues, such as the sheet thickness being very thin at 0.025 mm, and loss characteristics decreasing significantly when stress is applied to the iron core, making it impossible to apply these high-performance materials to motors.

Meanwhile, copper loss is mainly determined by the relationship between the coil resistance and current, and measures can be taken to reduce the coil resistance by cooling, or to reduce the current by suppressing the decrease in the residual magnetic flux density of the magnet. Furthermore, in recent years, designs have been made for automobile drive motors and the like to reduce resistance by increasing the ratio of the conductor to the cross-sectional area of the stator slot (space factor).

However, segment coils use rectangular wires, which can increase the space factor in the slot, and are constructed by twisting the straight part of the coil protruding on the other side after insertion into the slot, and then welding the conductors together to connect them.

This results in a complex structure for the coil end portion (the portion of the coil that extends axially from the core), and the volume of the portion where these conductors are welded together becomes large, resulting in problems such as a slightly higher resistance value.

As mentioned above, twisting the coil places stress on the iron core, which can cause problems such as deterioration of the magnetic properties of the iron core and damage to the insulating paper, reducing the insulating performance between the coil and the iron core, resulting in many defects.

The technology described in Patent Document 1 involves inserting a two-legged hairpin-shaped conductor segment into the stator coil of a motor, bending each of the segments at the coil end on the opposite side to the inserted side, and welding the segments to the bent conductor of another hairpin-shaped coil arranged in the circumferential direction to form a circular coil.

The method described in Patent Document 1 has the effect of increasing the slot space factor, but on the other hand, it is necessary to bend and shape the thick, hard rectangular conductor during manufacturing, which causes problems such as stress on the stator core, damage to the slot insulator, and difficulty in ensuring the reliability of the welded joints due to residual stress remaining in the connection parts from bending, so there is room for improvement in this manufacturing method.

Another problem is that because space must be left around the welded area to perform the welding, the coil end becomes larger on the welding side.

One of the techniques that attempts to improve on these issues is described in Patent Document 2. Patent Document 2 shows a method of dividing a stator coil using a segment conductor insertion method in the axial direction, making the divided end faces into a V-shape that can be combined, and joining the combined parts of the V-shape using a conductive paste adhesive to form a conductor coil.

The method described in Patent Document 2 eliminates the need for welding at the coil end, and is therefore expected to reduce the coil resistance by optimally designing the shape of the coil end.

However, because the conductors must be assembled one by one by applying adhesive, there are issues with increased labor costs and ensuring reliability. If conductive paste adhesive is not used, it is generally difficult for the V-shaped mating parts to make surface contact, and it is known that there will be line contact somewhere on the V surface. Furthermore, considering manufacturing variations, it is unlikely that all of the wires will be held on the same axial surface, and it is assumed that it will be difficult to manage each wire in a position where it can be firmly connected (contacted).

Patent document 3 shows a configuration in which coils divided in the axial direction are connected using protrusions and holes, or convex and concave shapes. This is also characterized by the fact that the connection is made visible in order to ensure connection reliability. After the connection process is performed, parts of the divided stator core are fitted in from the circumferential direction and assembled. This also has issues such as the need to confirm the reliability of the insertion of the contact connection parts, increased labor hours, and increased labor hours for core assembly.

Patent Document 4, like Patent Document 3, shows a method for connecting uneven coil end surfaces. After insertion into the slot, stress is applied to part of the coil to widen the inserted coil, resulting in a crimping effect that ensures a highly reliable connection (ensuring electrical conductivity). The method for widening the coil after insertion into the core is not clearly described, and there are concerns that doing this at all connection points could result in an increase in the number of steps required for the widening process.

In contrast, the method shown in Patent Document 5 shows a method of firmly joining the coil mechanically by using the shape of the coil tip as a press-fit tolerance. A resin bobbin is used to firmly secure the coil insertion area while applying stress to the uneven tip, resulting in a highly reliable connection.

JP 2011-239651 A JP 2015-23771 A JP 2013-208038 A JP 2016-187245 A International Publication No. WO2020/017133A1

The axially divided shape of the hairpin-shaped coil and the method of reassembling it shown in Patent Document 5 have the effect of increasing the space factor.

However, because the split parts are inserted and fitted inside the slots of the stator core, it is difficult to confirm that the fitted parts are properly inserted. It is difficult to make the insertion dimensions uniform at all fitting points due to manufacturing tolerances of the hairpin coil and local deformation of the coil due to differences in the stress conditions during insertion. In extreme cases, it is possible that conductors will not fit and will break, making it difficult to identify the location of the break and to repair it.

In addition, the typical manufacturing method for flat wire coils is to insert the coil in the axial direction, then bend the coil section opposite the insertion side and weld the ends. During this bending process, excessive stress is placed on the insulating paper and stator core, which often causes problems such as poor insulation.

Furthermore, when using low-loss materials such as amorphous for the stator core, the loss characteristics of the material may be significantly reduced due to stress, which may result in the design motor characteristics not being satisfactory.

The object of the present invention is to realize a rotating electric machine and a manufacturing method for the rotating electric machine that can assemble split assembly type segment coils without applying excessive stress to the stator core or insulators, even when a soft magnetic material with excellent magnetic properties is used for the core.

To solve the above problems, the present invention is configured as follows:

A rotating electric machine including a plurality of segment coils, a stator core having slots for accommodating the plurality of segment coils, and a rotor,
The segment coil has a conductor portion and a coating portion that coats the conductor portion,
The conductor portion has a straight portion that is stored in the slot and a coil end portion that protrudes from the end surface of the stator core, the coil end portion extends in a direction approximately perpendicular to the axial direction of the stator core and has a flat surface exposed from the coating portion, and the ends of the straight portions of the multiple segment coils are convex or concave portions, and the convex and concave portions are fitted into and connected to each other within the slot .

In addition, in a manufacturing method for a rotating electric machine having a plurality of types of segment coils, a stator core having slots for accommodating the plurality of types of segment coils, and a rotor, a first step of forming flat surfaces extending in a direction substantially perpendicular to the axial direction of the stator core at coil end portions of the plurality of types of segment coils,
The method includes a second step of inserting the straight portions of the multiple types of segment coils into the slots of the stator core, and a third step of pressing the flat surfaces of the multiple types of segment coils with an insertion jig having a different protrusion for each of the multiple types of segment coils, thereby fitting the convex and concave portions into each other within the slot , wherein in the first step, a recess is formed in approximately the center of the flat surface, and in the third step, the protrusion is inserted into the recess and the flat surfaces of the multiple types of segment coils are pressed with the insertion jig .

According to the present invention, it is possible to realize a rotating electric machine and a manufacturing method for a rotating electric machine that can assemble split assembly type segment coils without applying excessive stress to the stator core or insulators, even when a soft magnetic material with excellent magnetic properties is used for the iron core.

1 is an oblique view illustrating a hairpin-shaped segment coil according to one embodiment of the present invention. FIG. FIG. 1B is a partially enlarged view of FIG. 1A. 1C is an illustration of the flat surface shown in FIG. 1B. FIG. 2 is an explanatory diagram of another example of the flat surface shown in FIG. 1B. FIG. 2B is a cross-sectional view of an example of the flat surface shown in FIG. 2A. FIG. 2C is a cross-sectional view of another example of the flat surface shown in FIG. 2B. FIG. 10 is an explanatory diagram of an example of a manufacturing method for a radial gap type rectangular wire distributed winding stator different from the present invention. FIG. 10 is an explanatory diagram of an example of a manufacturing method for a radial gap type rectangular wire distributed winding stator different from the present invention. FIG. 10 is an explanatory diagram of an example of a manufacturing method for a radial gap type rectangular wire distributed winding stator different from the present invention. FIG. 10 is an explanatory diagram of an example of a manufacturing method for a radial gap type rectangular wire distributed winding stator different from the present invention. FIG. 2 is a diagram showing a cross section of a radial gap type distributed winding stator which is an example different from the present invention. FIG. 4B is an enlarged cross-sectional view of the arrangement of the enamel-coated electric wires in the example shown in FIG. 4A. FIG. 2 is a diagram showing a slot arrangement of a conductor to be inserted into an insulating bobbin in one embodiment of the present invention. FIG. 2 is a diagram showing an example of a stator structure in an embodiment of the present invention. FIG. 2 is a diagram showing an example of a stator structure in an embodiment of the present invention. FIG. 2 is a diagram showing a state in which resin insulating bobbins are inserted into all slots in one embodiment of the present invention. 1A to 1C are diagrams showing a method of assembling a hairpin-shaped segment coil to a stator core in one embodiment of the present invention. 13 is a diagram showing a state in which a hairpin-shaped coil is arranged on a stator in an example different from the present invention. FIG. FIG. 7B is a partial enlarged view of a coil end portion in the example shown in FIG. 7A. FIG. 2 is a perspective view of a stator core structure assembled with a hairpin-shaped coil in one embodiment of the present invention. FIG. 8B is an enlarged view of a portion of the stator core shown in FIG. 8A. 8B is a view of the coil end portion of the stator core shown in FIG. 8A projected from the axial direction. 13A and 13B are diagrams showing an annular insertion jig for inserting a coil end portion on the connection line side; FIG. 4 is a diagram showing an inserted state of the stator coil. FIG. 2 is a diagram showing an electrode placed in a plating solution. FIG. 13 is an explanatory diagram showing plating only on the inner portion of the recess. FIG. 13 is an explanatory diagram showing plating only on the outer portion of the protrusion. 1 is a diagram illustrating a circuit configuration when a pulse current is applied to a fitting portion to resistance weld the fitting portion after assembling the hairpin-shaped coil of the present invention to a stator core. FIG. 11A to 11C are diagrams showing a method for measuring the resistance value of the fitting portion after assembling the hairpin-shaped coil of the present invention to a stator core. FIG. 4 is a diagram showing a part of a wave winding connection circuit. FIG. 13 is a diagram showing the insulation protection of the stator after assembly and inspection. FIG. 13 is a diagram showing the insulation protection of the stator after assembly and inspection. FIG. 2 is a diagram showing a terminal connection board for connecting terminal wires. FIG. 1 is a diagram showing a Y-connection. FIG. 4 is a diagram showing the wiring structure of the terminal portion. FIG. 2 is a perspective view illustrating the relationship between a stator and a rotor. FIG. 2 is a schematic cross-sectional view of one embodiment assembled as a motor.

The following describes an embodiment of the present invention with reference to the drawings.

The following explanations are given to specific examples of the contents of the present invention, and the present invention is not limited to these explanations. Various changes and modifications are possible by those skilled in the art within the scope of the technical ideas disclosed in this specification. Furthermore, in all figures used to explain the present invention, parts having the same functions are given the same reference numerals, and repeated explanations may be omitted.

Figure 1A is a perspective view of the structure of a hairpin-shaped stator coil conductor used in a stator of a radial gap type rotating electric machine according to one embodiment of the present invention. Figure 1A shows a hairpin-shaped segment coil 1 (hereinafter sometimes abbreviated as hairpin-shaped coil 1 or segment coil 1) with a concave tip. This hairpin-shaped segment coil 1 has a straight portion 5 that is placed in the slot of the motor stator, and a coil end portion 6 that protrudes from the end surface of the motor stator core and serves to connect the other straight portion 5. The straight portion 5 and the coil end portion 6 are the conductor portion of the hairpin-shaped segment coil 1, and this conductor portion is covered by a coating portion 4 (described later).

At the coil end 6, the base of the bend R toward the coil end is connected to the base of the bend R on the opposite side in a mountain shape, and the apex of the mountain is bent to change the coil position. This coil conductor is suitable for use with highly electrically conductive materials such as copper or aluminum, and the surface is coated with insulating paint such as enamel or inorganic coating.

These coil conductors are usually connected to other parts using welding, crimping, soldering, etc., so they often use high-purity metals such as oxygen-free copper.

In one embodiment of the present invention, as shown in FIG. 1A, the insulating coating is peeled off from the apex of the coil end portion 6, and the peeled surface is provided with a flat surface 2 that extends in a direction approximately perpendicular to the illustrated Z-axis direction (the axial direction of the stator core), which is the direction of the rotor's rotation axis. The flat surface 2 is exposed from the coating portion 4. In this embodiment, the bottom surface of the round hole structure is the flat end surface 2.

Figure 1B is a partially enlarged view of the coil end portion 6, showing that the flat end surface 2 is the bottom surface of the circular hole structure.

During the hairpin coil manufacturing process, the conductive surface of the hairpin-shaped segment coil 1 of the present invention can be formed by pressing or cutting with an end mill.

Figure 2A shows an example of the flat surface 2, which is the conductive surface of the hairpin-shaped segment coil 1 shown in Figures 1A and 1B, and Figure 2C shows a cross-section of an example of the flat surface 2 shown in Figure 2A. Also, Figure 2D shows a cross-section of the flat surface 2 shown in Figure 2B.

Figure 2A shows an enlarged view of flat surface 2, which is the conductive surface shown in Figure 1A. This structure forms a circular depression in the center of the apex of coil end portion 6. This structure has a cross-sectional shape as shown in Figure 2C, and the conductor portion below enamel coating 4 is chamfered to form flat surface 2. This type of shape can be created by cutting using an end mill or the like.

Furthermore, the flat surface 2 is structured so that a tiny depression 7 is provided in the center. As will be explained later, this depression 7 serves as a guide when positioning the contact in this depression 7 area.

Figure 2B is an explanatory diagram of another example of the flat surface 2. The flat surface 2 is exposed from the enamel coating 4. In other words, the enamel coating 4 at the apex of the coil end portion 6 is peeled off to form the conductive flat surface 2, and a minute depression 7 is provided in approximately the center of the flat surface 2. This shape can be manufactured by a method in which the enamel coating 4 is peeled off in advance by pressing the relevant area when molding the hairpin-shaped segment coil 1.

In addition, the minute depressions 7 can be easily created by pressing a punch into the relevant locations, so this is thought to be one structure that can shorten the number of manufacturing steps. As shown in Figure 2D, which shows a cross section of the example shown in Figure 2B, the structure has minute depressions 7 formed on the surface where the enamel coating 4 has been peeled off.

Figures 3A, 3B, 3C, and 3D are diagrams showing an example of a manufacturing method for a radial gap type distributed winding stator that differs from the present invention.

Figure 3A shows the structure of a slot insulator. The slot insulator is made by folding paper such as aramid paper 19 as shown in Figure 3A to form a straw-shaped insulator. Figure 3B shows a hairpin-shaped coil. Usually, the enamel coating on both ends of the three-dimensionally formed coil is peeled off beforehand.

Then, as shown in Figure 3C, the hairpin-shaped coil is assembled by inserting it axially into the slot of the stator core 9 where the aramid paper insulation 19 is placed. All the coils need to be assembled at the same time, but for the sake of understanding, we will show the insertion of two coils. The two inserted hairpin-shaped coils are connected by bending the opposite coil ends and welding the ends together to form a single wave-wound coil.

When bending the coil legs of the opposite coil, a large amount of stress is applied to the insulator and stator core, which can lead to poor insulation due to damage to the insulator, and to poor performance of the soft magnetic material due to stress being applied to the core. In addition, welding of the butt joints poses issues such as damage to the enamel coating due to temperature increases during welding, and poor insulation due to enamel melting caused by sparks flying during welding.

Figure 4A shows the cross-sectional structure of a radial gap type distributed winding stator, which is an example different from the present invention shown in Figures 3A to 3D. The structure is such that an aramid paper insulating member 19 with a thickness of 0.2 mm is inserted into a square slot, and an enamel-coated conductor is inserted into it. The relationship between the insulator and the slot shape requires an assembly gap of about 0.05 mm to insert the aramid paper insulator 19. This takes into account the variation in the thickness of the aramid paper and the bending assembly tolerance. Similarly, an assembly tolerance of about 0.05 mm is required between the aramid paper insulating member 19 and the enamel-coated conductor, and it can be seen that the space factor, which is the ratio of the cross-sectional area of the conductor to the cross-sectional area of the slot, becomes smaller.

Figure 4B shows an enlarged cross-sectional view of the arrangement of the enamel-coated wire in the example shown in Figure 4A. Figure 4C shows the slot arrangement of the conductor for insertion into the insulating bobbin 14 in one embodiment of the present invention.

As shown in Figure 4C, a resin insulating member is placed in a rectangular slot, and a conductor is placed inside it. The insulating member can be manufactured by injection molding, which allows for dimensions with little variation. The resin is placed in the slot with a thickness of 0.2 mm, the same as the aramid paper insulating member, and the slot holes into which the conductors enter are structured to be independently insulated. The conductor is placed in the hole, but because the molding precision of the insulating bobbin 14 is higher than that of the previously described folded arrangement product and because this method does not require twisting of the coil after insertion, the tolerance relationship between the conductor and the insulating bobbin 14 can be minimized, and the space factor can be increased by placing a conductor with a sufficient cross-sectional area in the hole.

It is possible to further increase the space factor by increasing the dimensional tolerance of the conductor, but in this embodiment, the assembly gap is set to approximately 0.03 mm, which is a reasonable level for inexpensive production, taking into account manufacturing costs.

Figures 5A to 5C are diagrams showing an example of a stator structure in one embodiment of the present invention.

Figure 5A shows the stator core 9. Thin soft magnetic materials such as electromagnetic steel sheets are stamped out with a press and laminated to form the stator core 9. The slots 8 are rectangular in shape, and the teeth have a typical semi-closed shape at the tips of the teeth due to the protrusions at the tips. Figure 5B is an explanatory diagram of the insulating bobbin 14. An integrated resin insulating bobbin 14 with multiple holes, shaped as shown in Figure 5B, is inserted axially into the slot 8 and assembled. As mentioned above, the insulating bobbin 14 has a thin insulator thickness of 0.2 mm, similar to the case of aramid paper slot insulating paper. In addition, the area where the conductors are inserted is partitioned by a wall, and the shape is designed to ensure the creepage and spatial insulation distance between the conductors.

Figure 5C shows the state in which a resin insulating bobbin 14 with multiple holes is inserted into all of the slots 8. Since the insulating bobbin 14 has small dimensional tolerance variation, small gaps are sufficient for assembly.

Figure 6 is a diagram showing a method of assembling hairpin-shaped segment coils 1 to a stator core 9 in one embodiment of the present invention. In this figure, in order to make the structure easier to understand, a structure is shown in which two hairpin-shaped segment coils 1 are assembled at the upper axial position and one hairpin-shaped segment coil 1 is assembled at the lower axial position.

As shown in FIG. 6(a), the tip of the straight portion 5 of the hairpin coil 1 is formed with a convex portion 3a, which is a convex portion, or a concave portion 3b, which is a concave portion, and a plating process 12 is applied to the cut surface formed to form the convex portion 3a and the concave portion 3b. The straight portion 5 of each hairpin coil 1 is inserted into the hole of the insulating bobbin 14 in the axial direction of the stator core 9, and is inserted into the slot 8 of the stator core 9, and the stator core 9 is assembled. FIG. 6(b) shows the completed insertion state of the three coils, and the cross-sectional view shown in FIG. 6(c) shows the cross-sectional state of the coil end portion 6, the straight portion 5, and the fitting portion, the concave portion 3a and the convex portion 3b, from the top. It can be seen that the enamel coating 4 is present on the coil end portion 6 and the straight portion 5.

The recessed portion 3a and the protruding portion 3b, which are the mating portions, are tin-plated, and the recessed portion 3a and the protruding portion 3b are tightly fitted into the slot 8, making them somewhat cramped against the slot hole of the insulating bobbin 14. The gap between the recessed portion 3a and the protruding portion 3b is plated to provide electrical conductivity, and the combination of these conductive portions forms a wave-wound coil.

If left as is, there is a risk that the fitting between the recess 3a and the protrusion 3b may come loose due to vibration, etc., so it is desirable to perform a varnish treatment to secure the hairpin-shaped coil 1 to the resin insulating bobbin 14, and the insulating bobbin 14 to the stator core 9 and the coil end portion 6. It is also possible to pass an electric current through this portion and weld it locally, as described below.

After welding, it is desirable to fix the hairpin-shaped coil 1 and strengthen its insulation through processes such as dipping, coating, impregnation, vacuum impregnation, and drying with epoxy or unsaturated polyester insulating resin. Another method is to encase the coil end portion 6 in resin using injection molding or transfer molding.

Figures 7A and 7B show a hairpin-shaped coil placed on a stator in an example different from the present invention.

Figure 7A shows the state in which the segment coil 1 is inserted circumferentially into the slot holes in the first and second rows on the inner periphery of one phase. Figure 7B is a partially enlarged view of the coil end portion in the example shown in Figure 7A.

In Figures 7A and 7B, in addition to the coil 10a with a standard pitch that spans six slots, there are coils with different shapes, such as a short-pitch coil 10b with a five-slot pitch, a long-pitch coil 10c with a seven-slot pitch, and an outlet wire coil 10d. When attempting to insert these coils in the axial direction, the coil end height of the long-pitch coil is the highest, so it can be seen that even if the entire coil end is pressed axially with a flat pressing tool, it is not possible to apply an insertion force to the standard-pitch coil or the short-pitch coil.

In addition, when the jig is brought into contact with the coil near the apex of the coil end to apply axial insertion force, the enamel coating causes slippage between the jig and the coil end, making it impossible to uniquely position the coil.

In addition, pressing too hard to keep the position from shifting can damage the insulation at the coil end, and pushing the coil at an angle can cause the coil to tilt, requiring even greater insertion force.

Figures 8A, 8B, and 8C are perspective views showing the structure of a stator core 9 assembled with a hairpin-shaped coil 1 in one embodiment of the present invention.

Figure 8A shows a perspective view of the entire stator core 9. The coil end apexes of all hairpin-shaped coils 1 have flat end faces 2 that are conductive surfaces perpendicular to the axial direction.

Figure 8B shows an enlarged view of a portion of the stator core 9 shown in Figure 8A. It can be seen that the short pitch coil, long pitch coil, and standard pitch coil all have flat surfaces 2, which are conductive surfaces, at the apexes of their coil ends.

Figure 8C shows the coil end portion 6 of the stator core 9 shown in Figure 8A projected from the axial direction. It can be seen that the surfaces 2a, 2b, and 2c, which are the flat conductive surfaces 2 provided at the apexes of the short pitch coil, long pitch coil, and standard pitch coil, are all visible. Therefore, by applying an insertion force perpendicular to this surface, i.e. parallel to the axis of the stator core 9, the coil can be inserted parallel to the axis.

Figures 9A and 9B show an example of an annular insertion jig for applying an insertion force parallel to the Z axis to the coil with the coil end shape shown in Figures 8A to 8C. Figure 9A shows an annular insertion jig 31 for inserting the coil end portion 6 on the connection line side. At predetermined circumferential positions of the insertion jig 31, there are multiple insertion pressure pins 32, which are pin-shaped protrusions for pressing the flat surface 2, which is the conductive surface installed at the apex of the coil end portion 6. In this example, 138 insertion pressure pins 32 are arranged.

The insertion pressure pins 32 have a positioning protrusion 33 at the center of their tips for positioning, which can fit into minute positioning recesses 7 provided on the flat surface 2 of the coil end portion 6. These insertion pressure pins 32 are also positioned relative to the flat surface 2, which is the conductive surface at the apex of the coil end portion 6, with the pins that press on the surface of the long-pitch coil being short and the pins that press on the surface of the short-pitch coil being long, positioned in the prescribed positions.

Figure 9B shows the stator coil insertion state. The lower coil end shown, which does not have short-pitch or long-pitch connection lines, can be fixed with a flat base jig 30. The upper coil end 6, which has a mixture of long-pitch and short-pitch coils, is inserted by positioning the pin tip of the insertion jig 31 shown in Figure 9A on the flat surface 2, which is a specified conductive surface, and applying an insertion force in the axial direction.

This allows the user to check the relative dimensions between the jigs and thereby confirm the position at which the coil has been fully inserted, thereby reducing insertion defects such as insufficient coil insertion.

Figures 10A, 10B, and 10C show a method for plating the coil tip. Figure 10A shows plating liquid 24 placed in plating tank 25 and electrode 23 placed in plating liquid 24. The hairpin-shaped coil 1 in one embodiment of the present invention is a hairpin-shaped coil without enamel coating 4, so the structure makes it easy to place electrode 23 anywhere on hairpin-shaped coil 1.

In FIG. 10A, the flat surface 2, which is the conductive surface of the coil end portion 6, is electrically connected to a DC power source 21 by a clip 22, and is connected to an electrode 23. FIG. 10B and FIG. 10C are explanatory diagrams showing plating only on the inside of the recess 3a and the outside of the protrusion 3b. As shown in FIG. 10B and FIG. 10C, plating can be performed only on the inside of the recess 3a, which is the fitting portion where the end is cut, and on the outside of the protrusion 3b, which is the fitting portion. The parts to be plated are the 5 mm parts of the recess 3a and the protrusion 3b, and the other parts are masked with an enamel coating, so plating can be performed in a simple manner without investing in labor and equipment to control the liquid level and the variation in the coil attitude control.

The plating thickness tolerance is about 5 to 10 μm, which is a sufficient dimension for assembly with an assembly gap of 0.03 mm. The plating material is chosen to prevent the connections of the copper or aluminum conductors from losing conductivity due to oxidation, and possible materials include metals such as chromium, nickel, and tin, which are less susceptible to deterioration, and gold and silver, which have high conductivity. In this example, tin, which is the least expensive, will be selected as the plating material.

By applying tin plating, the dimensional relationship between the recessed portion 3a and the protruding portion 3b changes from a clearance fit to a tight fit tolerance, and by joining them in the axial direction of the stator core 9, they can be fastened while applying stress to each other.

Figure 11 shows a method for resistance welding a hairpin-shaped coil 1 using a flat surface 2, which is a conductive surface, in one embodiment of the present invention. After assembling the hairpin-shaped coil 1 to the stator core, electrodes are placed between the specified coil ends and a pulsed current is applied.

This generates Joule heat in localized areas of the mating surfaces (the mating surfaces of the concave portion 3a and the convex portion 3b) with a high resistance value, making it possible to locally weld and join them. When welding is performed by passing a current between the flat surfaces 2, which are the conductive surfaces of adjacent coils, if the neutral point or output wire of the terminal portion is not connected, the ends become open. Therefore, by appropriately selecting the flat surfaces 2, which are the conductive surfaces of adjacent coils, as shown in the figure and applying a current, it is possible to perform resistance welding between the concave portion 3a and the convex portion 3b at each location. This causes the concave portion 3a and the convex portion 3b to be welded to each other.

Figure 12 shows a method for inspecting the conductive resistance of the mating portion (concave portion 3a and convex portion 3b) after assembling the hairpin-shaped coil 1 of the present invention to the stator core 9. Figure 12 shows a diagram of measuring the resistance of the flat surface 2, which is the conductive surface of adjacent coil ends as shown in Figure 11, with a resistance meter. When the mating portion between the concave portion 3a and the convex portion 3b is not in contact at all, the resistance value is ∞, and the resistance value differs when half is mated and when the entire portion is inserted. By measuring this resistance value, the soundness of the mating state can be evaluated.

Figure 13 shows a portion of the wave winding connection circuit. It can be seen that there is one mating connection between the inner input wire circle 1 and the coil end conductive flat surface circle 2. For example, there are eight mating connections between the conductive flat surface 2 and circle 9. In this way, the resistance between the output wire and input wire is measured and evaluated, and if there is a problem with the resistance, the range can be gradually narrowed to identify the specific problematic point. Once identified, it is possible to make corrections to improve the mating resistance using the resistance welding principle as shown in Figure 11.

Figures 14A and 14B show the insulation protection of the stator after assembly and inspection. Since a conductive portion is open in part of the coil end portion 6, there is a risk of discharge when a conductive portion is nearby, for example, when the air pressure is low inside an airplane during flight. In such cases, it is necessary to fill the conductive portion with insulating material, so insulation measures are taken by dipping or impregnating with insulating varnish. As mentioned above, the flat surface 2, which is the conductive surface, has a structure that appears entirely on the axial projection surface of the stator, so that only that part can be insulated by applying an appropriate amount to that part with the dispenser nozzle 26 of the dispenser (fixed-volume liquid injection device) 27.

Insulation measures can also be taken by simultaneously varnish fixing the entire coil, or by molding and encasing the coil end in unsaturated polyester resin or similar. At the coil end end face on the lower axial side, all of the conductive flat surfaces are at the same height in the axial direction, so methods such as taping with doughnut-shaped insulating tape are also possible.

Figures 15A, 15B, and 15C show the wiring structure of the terminal part. The varnish treatment shown in Figure 14A is necessary for use at low atmospheric pressure, but is not essential when the voltage is low or when used at normal atmospheric pressure.

Figure 15A shows a terminal connection board 40 for connecting the terminal wires. The terminal connection board 40 is configured as shown in the figure, with a ring-shaped neutral point connection bar 44, a series connection connection bar 42, and an output line connection bar 43 on a base plate 41 made of a non-conductive epoxy resin or the like. With this configuration, the base plate 41, which is an insulating member, is placed on the axial upper part of the coil end part of the stator, so there is less concern about discharge to the housing, etc. Even during the wiring work, soldering and welding work are performed on the upper part of the base plate 41 made of insulating material, so the structure prevents foreign matter from entering the flat surface 2, which is the conductive surface of the coil end part 6. Figure 15B is a diagram showing a Y-connection connection. The circle numbers in Figure 15C indicate slot numbers.

The method for manufacturing a rotating electric machine in one embodiment of the present invention is a method for manufacturing a rotating electric machine having multiple types of segment coils 1, a stator core having slots 8 that accommodate the multiple types of segment coils 1, and a rotor.

The manufacturing method for a rotating electric machine according to the present invention includes a first step of forming flat surfaces 2 extending in a direction approximately perpendicular to the axial direction of a stator core 9 on the coil end portions 6 of the multiple types of segment coils 1, a second step of inserting the straight portions 5 of the multiple types of segment coils 1 into the slots 8 of the stator core 9, and a third step of pressing the flat surfaces 2 of the multiple types of segment coils 1 with an insertion jig 31 having different protrusions 32 for each of the multiple types of segment coils 1 to fit the convex portions 3b and the concave portions 3a into each other within the slots 8.

In addition, in the manufacturing method of the rotating electric machine of the present invention, in the first step, a recess 7 is formed in approximately the center of the flat portion 2, and in the third step, the protrusion 32 is inserted into the recess 7 and the flat surface 2 of the multiple types of segment coils 1 is pressed by the insertion jig 31.

The manufacturing method for a rotating electric machine of the present invention also includes a fourth step of passing a current through the flat surface 2 to weld the convex portion 3b and the concave portion 3a that are fitted together within the slot 8.

The manufacturing method for a rotating electric machine of the present invention also includes a fifth step of passing an inspection current through the flat surface 2 and inspecting the connection state between the convex portion 3b and the concave portion 3a based on the resistance value of the convex portion 3b and the concave portion 3a that are fitted together in the slot 8.

Figures 16A and 16B show a structure in which stators assembled using the methods shown in Figures 6A to 15C are combined into a rotating electric machine (motor).

Figure 16A shows a perspective view explaining the relationship between the stator and rotor. The rotor of the motor is a rotating rotor core 50 fixed to a shaft 57. This embodiment shows an example of a permanent magnet synchronous motor, but the rotor may be a cage conductor rotor of an induction motor or a magnetic salient pole rotor of a reluctance motor. In the case of a permanent magnet synchronous motor, permanent magnets 60 are arranged inside or on the surface of the rotor core 50. The rotor is arranged inside the stator, and the rotor surface and the stator inner surface face each other via a gap, and the structure operates as a motor by exchanging magnetic flux.

Figure 16B is a schematic cross-sectional view of one embodiment assembled as a motor. The rotor shaft shown above has ball bearings 54, 55 arranged on the output side and the anti-output side of the shaft, and the inner circumferential surfaces of the ball bearings 54, 55 are held rotatably together with the shaft 57 with the outer periphery of the ball bearings 54, 55 fixed. The outer periphery of the ball bearings 54, 55 is held by the output side bearing holder 51 and the rear side bearing holder 52, and these bearing holders 51, 52 are configured in a state of maintaining coaxiality by the housing 53. In addition, the housing 53 is configured to be held by applying stress in the axial direction by tightening bolts 56, 59 in the axial direction. The stator is held and fixed at a predetermined location in the axial direction of the housing 53. In this state, the terminal connection board 40 that integrates the coil group is partially in contact with the axial surfaces of the bearing holders 51, 52 and is held in a state of applying stress in the axial direction.

As described above, according to the present invention, it is possible to realize a rotating electric machine and a manufacturing method for a rotating electric machine that can assemble split assembly type segment coils without applying excessive stress to the stator core or insulators, even when a soft magnetic material with excellent magnetic properties is used for the iron core.

The motor stator with a high space factor according to the present invention can reduce the conductor resistance value of the coil, which makes it possible to reduce copper loss. In addition, since bending is not performed during assembly, there is no need to leave any assembly margin, and the air space in the slot can be minimized, which improves the heat transfer performance for transferring heat generated from the coil to the core.

The above effects reduce the amount of heat generated by the motor and improve its cooling capacity, thereby improving the efficiency of the motor. In addition, since no stress is applied to the motor's stator core during assembly, there is no deterioration in the performance of the soft magnetic material, making it possible to use high-performance soft magnetic materials. Furthermore, the insulation of the hairpin coils can be maintained in separate chambers for each coil by the slot insulation member, making it possible to ensure both creepage distance and insulation distance.

Furthermore, because this insulating material is made of resin and is manufactured by injection molding, it has high dimensional accuracy and can be made thin. This allows the thickness of parts that would otherwise be thick due to the double layering of insulating paper to be made thinner, making it possible to further improve the space factor and thermal conductivity.

The hairpin coil structure of the present invention is suitable for split coil assembly methods, in which axial coil stress application is essential for assembly.

Compared to the conventional hairpin coil insertion, anti-insertion side bending, and welding methods, the coil has very little effect on the insulating material and stator core. Some stator cores are sensitive to stress and experience increased iron loss, making this a superior method for high-grade electromagnetic steel sheets and low-loss materials such as amorphous.

It is also effective in preventing damage to the coil and insulation during insertion, as well as coil deformation, and can reduce the number of coil types required, thereby reducing the required assembly jigs and capital investment.

In addition, we can guarantee manufacturing reliability, grasp quantities, and supply stators that are easy to assemble with optimal shapes for both the coil ends and slots.

In addition, the assembly process can be simplified, which is expected to help reduce motor costs.

1: Hairpin coil, 2: Flat end surface, 3a: Concave, 3b: Convex, 4: Enamel coating, 5: Straight section, 6: Coil end, 7: Depression, 8: Slot, 9: Stator core, 12: Plating section, 14: Insulating bobbin, 21: DC power source, 22: Clip, 23: Electrode, 24: Plating liquid, 25: Plating tank, 26: Dispenser nozzle, 27: Dispenser (liquid injection device), 30: Base jig, 31: Insertion jig, 32: Pressure pin (projection) for insertion, 33: Pointed projection for positioning, 40: Terminal connection board, 41: Base plate, 42: Series connection line bar, 43: Output line connection bar, 44: Neutral point connection bar, 50: Rotor core, 51, 52: Bearing holder, 53: Housing, 54, 55: Ball bearing, 56, 59: Bolt, 57: Shaft, 60: Permanent magnet

Claims (7)

A rotating electric machine including a plurality of segment coils, a stator core having slots for accommodating the plurality of segment coils, and a rotor,
The segment coil has a conductor portion and a coating portion that coats the conductor portion,
the conductor portion has a straight portion accommodated in the slot and a coil end portion protruding from an end surface of the stator core,
the coil end portion extends in a direction substantially perpendicular to an axial direction of the stator core and has a flat surface exposed from the coating portion,
A rotating electric motor characterized in that the ends of the straight portions of the multiple segment coils are convex or concave portions, and the convex and concave portions are fitted into and connected to each other within the slots. 2. The rotating electric machine according to claim 1 ,
A rotating electric machine, characterized in that a recess is formed in approximately the center of the flat surface. 3. The rotating electric machine according to claim 2 ,
A rotating electric machine comprising: an integrated insulating bobbin having a plurality of holes and inserted into the slot, the straight portion being inserted into the holes of the insulating bobbin and housed in the slot. 4. The rotating electric machine according to claim 3 ,
a straight portion inserted into the slot, the straight portion having a convex shape and a concave shape, the straight portion being welded to one another; A method for manufacturing a rotating electric machine including a stator core having multiple types of segment coils, slots for accommodating the multiple types of segment coils, and a rotor, comprising:
A first step of forming flat surfaces extending in a direction substantially perpendicular to an axial direction of the stator core at coil end portions of the plurality of types of segment coils;
A second step of inserting straight portions of the plurality of types of segment coils into the slots of the stator core;
The end of the straight portion of the plurality of types of segment coils is a convex portion or a concave portion, and a third step is to press the flat surface of the plurality of types of segment coils with an insertion jig having a different protrusion for each of the plurality of types of segment coils to fit the convex portion and the concave portion into each other within the slot;
Equipped with
In the first step, a recess is formed in a substantially central portion of the flat surface,
A method for manufacturing a rotating electric machine, characterized in that in the third step, the protrusion is inserted into the recess and the flat surfaces of the multiple types of segment coils are pressed using the insertion jig . 6. The method for manufacturing a rotating electric machine according to claim 5 ,
a fourth step of passing an electric current through the flat surface to weld the convex portion and the concave portion that are fitted together within the slot. 7. The method for manufacturing a rotating electric machine according to claim 6 ,
A manufacturing method for a rotating electric machine, comprising a fifth step of passing an inspection current through the flat surface and inspecting the connection state between the convex portion and the concave portion based on the resistance value of the convex portion and the concave portion engaged with each other within the slot.