Patent ID: 12231009

DESCRIPTION OF EMBODIMENTS

[Rotating Electric Machine]

First, an outline of a rotating electric machine of the present embodiment will be described. The rotating electric machine of the present embodiment is a rotating electric machine suitable for use in traveling of an automobile because a rectangular wire capable of reducing the size and increasing the output is used. Examples of automobile using a rotating electric machine include a hybrid type electric vehicle (HEV) including both an engine and a rotating electric machine, and an electric vehicle (EV) that travels only with a rotating electric machine without using an engine. However, the rotating electric machine described below can be applied to any type. A rotating electric machine used for a hybrid type automobile will be described below as an example.

FIG.1is a cross-sectional view of a rotating electric machine100according to an embodiment of the present invention. This rotating electric machine100is a three-phase electric motor with a built-in permanent magnet. In the rotating electric machine100, a stator coil110is wound around a stator core111, and when a three-phase alternating current is supplied to the stator coil110, a rotor120operates as an electric motor that rotates. When the rotating electric machine100is driven by the engine, the rotating electric machine operates as a generator that generates three-phase alternating current. That is, the above function can be selectively used depending on the traveling state of the automobile.

As illustrated inFIG.1, the rotating electric machine100includes a housing130and a stator112fixed to the housing130. As described above, the stator112includes the stator coil110and the stator core111. The rotor120is rotatably disposed inside the stator core111via a void140. The rotor120includes a rotor core121, a permanent magnet150, and a non-magnetic abutting plate160. The rotor core121is fixed to a cylindrical shaft170. In the following description, a shaft center direction of the shaft170is referred to as “axial direction”, a direction rotating about the shaft center is referred to as “circumferential direction”, and a radial direction about the shaft center is referred to as “radial direction”.

The housing130has an end bracket180provided with bearings10A and10B, and the shaft170is rotatably held by these bearings10A and10B. The shaft170is provided with a resolver190that detects a position of a pole and a rotation speed of the rotor120.

FIG.2is a cross-sectional view of the rotating electric machine100illustrated inFIG.1, taken along line A-A. InFIG.2, the housing130and the stator coil110are not illustrated. In the stator core111, a plurality of slots200extending in the axial direction is arranged at equal intervals in the circumferential direction. The number of slots200is48in the present embodiment, for example. The stator coil110is accommodated in the slot200.

Although not illustrated, an insulating paper (so-called slot liner) is disposed in each slot200. Disposed between the stator coils110inserted into the slot200and between the stator coil110and the inner surface of the slot200, the insulating paper improves the dielectric strength voltage between the stator coils110and between the stator coil110and the inner surface of the slot200. The insulating paper is, for example, an insulating sheet of heat-resistant polyamide paper, and has a thickness of about 0.1 to 0.5 mm.

In the rotor core121, rectangular parallelepiped magnet insertion holes are arranged at equal intervals in the circumferential direction in the vicinity of the outer peripheral part. A permanent magnet150is embedded in each magnet insertion hole, and fixed with an adhesive or the like. The width of the magnet insertion hole in the circumferential direction is formed to be larger than the width of the permanent magnet150in the circumferential direction, the magnetic voids151are formed on both sides of the permanent magnet150. This magnetic void151may be filled with an adhesive or may be fixed integrally with the permanent magnet150with a resin.

The magnetization direction of the permanent magnet150is oriented in the radial direction, and the orientation of the magnetization direction is reversed for each field pole. That is, if the surface on the stator side of the permanent magnet150for forming a certain magnetic pole is the N pole and the surface on the shaft side is the S pole, the surface on the stator side of the permanent magnet150forming the adjacent magnetic pole is the S pole, and the surface on the shaft side is the N pole. In the present embodiment, eight permanent magnets150are magnetized and arranged so that the magnetization direction is alternately changed for each magnetic pole at equal intervals in the circumferential direction, and the rotor120forms eight poles.

Note that the permanent magnet150may be embedded in the magnet insertion hole of the rotor core121after being magnetized, or may be inserted into the magnet insertion hole of the rotor core121before magnetized, and then magnetized by applying a strong magnetic field.

However, the permanent magnet150after magnetized has a strong magnetic force, and when the magnet is magnetized before the permanent magnet150is fixed to the stator112, a strong attractive force is generated between the permanent magnet150and the rotor core121at the time of fixing the permanent magnet150, and this attractive force hinders the work. There is a concern that dust such as iron powder adheres to the permanent magnet150due to strong attractive force. Therefore, it is desirable to magnetize the permanent magnet150after being inserted into the magnet insertion hole of the rotor core121, in order to improve the productivity of the rotating electric machine100.

[Stator of Rotating Electric Machine]

FIG.3is a perspective view of the stator112. The stator112is fixed on the inner peripheral side of the housing130and includes the cylindrical stator core111and the stator coil110attached to this stator core111. AU-shaped coil end110aof the plurality of stator coils110is formed at one axial end of the stator core111. On the other hand, a weld side coil end110bin which welded parts of the stator coils110are arranged in a circular shape is formed at an end portion on the opposite side of the stator core111. The weld side coil end110bis welded by tungsten inert gas (TIG), for example. InFIG.3, an output drawing line is not illustrated.

In the stator core111, the stator core111includes laminated electromagnetic steel sheets (for example, silicon steel sheets)500, and the electromagnetic steel sheets500are shaped by punching or etching with a thickness of about 0.05 to 1 mm, and are laminated and then fixed by welding. The electromagnetic steel sheets500laminated by this welding are joined to suppress deformation of the electromagnetic steel sheets500due to a fastening force at the time of press-fitting into the housing130.

The stator core111is fitted and fixed to the inside of the cylindrical housing130by shrink fitting. As a specific assembling method, for example, the stator core111is first arranged, and this stator core111is fitted with the housing130heated in advance and having an inner diameter expanded by thermal expansion. Next, by cooling the housing130to contract the inner diameter, the outer peripheral part of the stator core111is tightened by the thermal contraction.

The stator core111is set such that an inner diameter dimension of the housing130becomes smaller than an outer diameter dimension of the stator core111by a predetermined value so as to prevent the stator core111from idling with respect to the housing130due to reaction caused by torque of the stator112during operation. As a result, the stator core111is firmly fixed in the housing130by shrink-fit fitting. The difference between the outer diameter of the stator core111and the inner diameter of the housing130at room temperature is called a fastening allowance, and by setting this fastening allowance on an assumption of maximum torque of the rotating electric machine100, the housing130can hold the stator core111with a predetermined fastening force. The stator core111is not limited to the case of fitting and fixing by shrink fitting, and may be fitted and fixed to the housing130by press fitting.

[Stator Coil]

Next, the stator coil110will be described.FIG.4is a schematic diagram of a segment of the stator coil110illustrated inFIG.3. In the present embodiment, a rectangular wire is used as the stator coil110, and the stator coil110is wound by a distributed winding method. The rectangular wire is provided with a surface coating of polyimide-based, polyester-based, polyesterimide-based, polyamideimide-based, or the like, but in the present embodiment, the material and surface shape of the coil surface are not limited. The distributed winding is a winding method in which the stator coil110is housed in the slots200separated across the plurality of slots200. The present invention is also applicable to the stator112having the stator coil110of concentrated winding instead of distributed winding.

A rectangular wire having a rectangular cross section is bent in the rotation axis direction at a vertex part110dto be shaped into a U-shape in advance by using foam shaping or the like, the stator coil110is inserted in the direction of the slot200provided with insulating paper300, and a linear part of the U-shaped part is inserted into two slots200separated from each other across the plurality of slots200. As illustrated inFIGS.7and8, in the stator coil110on the coil end110aside are formed a first bent part110elocated close to the vertex part110dof the stator coil110shaped in a U shape and immediately above a part (parallel overlap part110g) where the stator coil110obliquely extends between the vertex part110dand the stator core111, and a second bent part110flocated close to the stator core111and immediately below a part (parallel overlap part110g) where the stator coil110obliquely extends between the vertex part110dand the stator core111.

Thereafter, a linear conductor portion110cprotruding to the opposite side in the axial direction of the stator core111is torsionally shaped, and the end part thereof is welded to the end part of another stator coil110similarly torsionally shaped. In this manner, one phase winding is formed by inserting the plurality of stator coils110into the slots200of the stator core111and connecting them.

The method for shaping the stator coil110described above is merely an example, and the stator coil110may be shaped in a U shape using a mold, or may be shaped in a U shape after the stator coil110is inserted into the slot200.

The stator coil110is fixed to the insulating paper300by varnish in the slot200, and the surface of the coil is protected by the insulating paper300. The insulating paper300is fixed to the stator core111with varnish. This prevents a decrease in thickness and breakage due to damage to the surface coating of the insulating paper300and the rectangular wire generated by vibration during rotation of the rotating electric machine100, and prevents a decrease in insulation quality of the rotating electric machine100. The varnish not only fixes the stator coil110and the stator core111via the insulating paper300, but also functions as heat dissipation for inducing heat generated in the stator coil110to the stator core111.

Apart of the stator coil110protruding from the stator core111is fixed to the adjacent stator coil110with the varnish to suppress vibration of the stator coil110during rotation of the rotating electric machine100.

The varnish has a liquid property, and examples thereof include polyester-based and epoxy-based, and may be a one-liquid type or a two-mixed-liquid type. The varnish is preferably of a thermosetting type that is solidified by heating, but may be of a cold setting type.

The varnish is preferably applied to both the coil end110aand the weld side coil end110b, but may be applied to only one of the coil ends110aand110b.

[Varnish Process]

FIG.5is a view illustrating a varnish process of the present embodiment, and illustrates a perspective view of the stator112.

The stator112in which the stator coil110is inserted into the slot200is heated before the varnish is applied. Although the stator112may be heated or the varnish may be heated, desirably the varnish is applied after the stator112is heated. In the varnish process of the present embodiment, a fixed amount of varnish is dropped to a target position using a dispenser, a liquid phase pump, a spray nozzle, or the like, and the dropped varnish is applied to the stator coil110. The term “drop” in the present description and claims means that the varnish discharged by an application device drips toward the stator coil110, and particles of the varnish may drip off discontinuously or drip off continuously. In addition, the size of the particles of the varnish is not limited. The “dropping position” is a position at which the varnish discharged by the coating device comes into first contact with the stator coil110, and usually, in one stator112, “drop” is performed a plurality of times while a relative positional relationship between the coating device and the stator coil is changed, and thus, there are a plurality of “dropping positions”.

Specifically, the varnish process includes the first varnish process of forming the first varnish portion by applying varnish to a position of stator coil110connected to the coil in slot200, the position being close to stator core111, and a second varnish process of forming the second varnish portion by applying varnish to a position farther from the stator core111(for example, near the vertex part110d) than that in the first varnish process. As a result, a non-existence region where the varnish is not applied is formed between the first varnish portion and the second varnish portion.

In the varnish process, the varnish dripping on the stator coil110moves on the surface of the stator coil110, but at that time, the varnish may come off the stator coil110and drip, and the dripping varnish may fall on the stator core111and adhere to the adhesion prohibited area of the stator core111.

For example, on the outer peripheral side of the stator112, when the varnish adheres to the outer surface of the stator core111, which is an adhesion prohibited area, the outer diameter of the stator112partially increases, and the stator112is not attached to the housing130. On the inner peripheral side of the stator112, when the varnish adheres to the inner surface of the stator core111, which is an adhesion prohibited area, the varnish interferes with the rotor120attached to the inner side of the stator112, and the rotor120cannot be arranged at a correct position, which causes trouble or failure in rotation. In order to prevent this, by setting the position where the varnish is applied to the stator coil110to a position close to the stator core111, the movement amount of the varnish on the coil surface is reduced, and the risk of the varnish coming off from the stator coil110is reduced. Specifically, the first varnish portion is formed by setting the varnish dropping position of the stator coil110of the outermost circumference to a position close to the stator core111, and the second varnish portion is formed by setting the varnish dropping position of the stator coil110other than that of the outermost circumference to a position close to the vertex part110d(for example, a part where a slope is formed by the stator coil110slightly below the vertex part110d). By setting the varnish dropping position in the first varnish process to a position closer to the stator core111than the varnish dropping position in the second varnish process, the first varnish portion is provided at a position closer to the stator core111than the second varnish portion. This makes it possible to reduce the movement amount of the varnish, reduce the risk of the varnish coming off from the stator coil110, and reliably fixing the stator coil110with sufficient varnish permeating into the slot200.

Each varnish process is performed in the order of the first varnish process and the second varnish process. The varnish applied to the stator coil110permeates into the core along the stator coil110. When the varnish drips from the coil of the outermost circumference to the stator core111, the varnish adheres to the adhesion prohibited area. Therefore, the varnish is applied to the outermost circumference as the first varnish process in a state where the varnish has not permeated the slot200. By applying the varnish to the outermost circumference in a state where the varnish has not permeated the stator core111, the permeability of the varnish is better than that in a case of being applied after the varnish is applied to another stator coil110, and overflow of the varnish from the slot200can be prevented, and generation of a defective product can be suppressed.

During the varnish process of the present embodiment, the stator112may be disposed with the axis being vertical, but the stator112is preferably disposed to be inclined due to accessibility of a dropping device and rotated about the axis. In particular, an inclination θ1of the stator112in the first varnish process is preferably larger than an inclination θ2of the stator112in the second varnish process. The inclination θ of the stator112in each varnish process is defined by an angle formed by the axial direction of the stator112and the varnish dropping direction (vertical direction), and when the inclination θ=0, the axial direction is vertical and the end face of the stator core111becomes horizontal.

In the second varnish process, since the varnish flows down the mesh portion of the stator coil110, when the stator112is inclined to the same extent as in the first varnish process, the varnish hardly permeates into the slot200, and the varnish does not reach the inside of the stator core111. Therefore, it is desirable that the inclination of the stator112in each varnish process satisfies θ1>θ2.

As illustrated in the drawing, in addition to the first varnish process and the second varnish process, a third varnish process of forming a third varnish portion by applying the varnish to the inner peripheral side of the stator coil110at a position closer to the stator core111than the second varnish portion to may be provided.

When the applied varnish drips down on the inner peripheral side of the stator coil110, there is a high risk that the varnish adheres to the stator core111. Therefore, the varnish is applied to a position close to the stator core111on the inner peripheral side of the stator coil110so that the varnish does not come off from the stator coil110and drip onto the stator core111when moving the stator coil110. Doing this makes it possible to reduce the movement amount of the varnish on the coil surface, reduce the risk of the varnish coming off from the stator coil110, and reliably fixing the stator coil110with sufficient varnish permeating into the slot200.

In the above description, the varnish is applied to the outer peripheral side in the first varnish process, but the varnish may be applied to the inner peripheral side. That is, when the third varnish process is not included, the varnish is dropped on the inner peripheral side in the first varnish process, and the varnish is dropped near the vertex part110din the second varnish process. When the third varnish process is included, the varnish is dropped on the inner peripheral side in the first varnish process, the varnish is dropped near the vertex part110din the second varnish process, and the varnish is dropped on the outer peripheral side in the third varnish process.

The varnish process including the third varnish process is preferably performed in the order of the first varnish process, the second varnish process, and the third varnish process, or may be performed in the order of the first varnish process, the third varnish process, and the second varnish process.

[Varnish Applied to Stator]

FIGS.6and7are perspective views of the stator112applied with the varnish of the present embodiment, andFIG.8is a view of the coil end110aof the stator112applied with the varnish of the present embodiment.

As illustrated inFIG.6, the stator coil110mounted on the stator112is fixed to the stator core111by varnish. The part of the stator coil110protruding from the end face of the stator core111is provided with the first varnish portion to which the varnish adheres in apart of the stator coil110close to the stator core111, the second varnish portion to which the varnish adheres above the first varnish portion, and the non-existence region where the varnish does not adhere between the first varnish portion and the second varnish portion.

As described above, when the varnish adheres to the adhesion prohibited area provided in the stator core111, a product becomes defective. However, in the stator112that is illustrated, the movement distance of the varnish of the outermost peripheral coil on the coil surface is shortened, the varnish can be prevented from dripping, and generation of a defective product can be suppressed.

As illustrated inFIGS.6,7, and8, the non-existence region where the varnish does not adhere is formed between the first bent part110eand the second bent part110f. The varnish dropped onto the vertex part110dsometimes stays in the first bent part110eof the stator coil110, and the staying varnish sometimes drips from the first bent part110eand adheres to the stator core111. Since the second bent part110fis close to the stator core111and the extension direction is changed by the second bent part110fsuch that the stator coil110is accommodated in the slot200, a gap between the stator coils110adjacent in the circumferential direction becomes larger on the stator core111side than that in the second bent part110f, and a space is generated. Therefore, when the varnish is dropped on the stator core111side relative to the second bent part110f, the dropped varnish falls into the space between the stator coils110and adheres to the adhesion prohibited area of the stator core111, resulting in a defective product. Therefore, the lower side relative to the second bent part110fis not appropriate as the varnish dropping position. Therefore, by providing the lower end of the first varnish portion and the upper end of the second varnish portion between the first bent part110eand the second bent part110fof the stator coil110, it is possible to suppress the varnish from staying in the stator coil110, and possible to reduce the risk that the varnish dripping from the stator coil110adheres to the stator core111.

Since the upper end part of the first varnish portion is provided between the first bent part110eand the second bent part110f, it is possible to suppress the varnish flowing along the stator coil110from dripping and adhering to the end part of the stator core111. In the first varnish process, the varnish is applied to a position closer to the stator core111than the first bent part110e(on the lower side in the drawing) and closer to the vertex part110dthan the second bent part110f(on the upper side in the drawing), that is, between the first bent part110eand the second bent part110f. Therefore, the upper end part of the first varnish portion is provided between the first bent part110eand the second bent part110f, and it is possible to suppress the dripping varnish from adhering to the end part of the stator core111.

As illustrated inFIG.8, the first varnish portion is formed such that the upper end part of the first varnish portion is disposed in the parallel overlap part110gwhere adjacent stator coils110are arranged to overlap in parallel when the stator112is viewed from the direction perpendicular to the axis. In this parallel overlap part110g, the stator coils110are preferably arranged to overlap in parallel with a gap. In the first varnish process, the varnish drops onto the coil of the rotating stator core111. At this time, since the staying varnish drips at the first bent part110e, the varnish dropping position is set to a position closer to the stator core111than the first bent part110e. When the adjacent stator coils110are separated from each other, the dropped varnish may fall into the gap and adhere to the adhesion prohibited area. Therefore, in the first varnish process, by dropping the varnish is onto the parallel overlap part110gwhere the adjacent coils form the parallel gap between the first bent part110eand the second bent part110f, the varnish flowing along the stator coil110is prevented from dripping and adhering to the stator core111.

Note that the present invention is not limited to the above-described embodiment, but includes various modifications and equivalent configurations within the scope of the appended claims. For example, the above-described embodiment has been described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to those including all the configurations described above. The configuration of a certain embodiment may be replaced partly by the configuration of another embodiment. The configuration of another embodiment may be added to the configuration of a certain embodiment.

Another configuration may be added to, deleted from, or substituted for a part of the configuration of each embodiment.

REFERENCE SIGNS LIST

10A,10B bearing100rotating electric machine110stator coil110a,110bcoil end110clinear conductor portion110dvertex part110efirst bent part110fsecond bent part110gparallel overlap part111stator core112stator120rotor121rotor core130housing140void150permanent magnet151magnetic void160abutting plate170shaft180end bracket190resolver200slot300insulating paper500electromagnetic steel sheet