Electric motor stators

Abstract

To provide an electric motor stator suitable for recycling a winding and a stator core without being affected by variations in varnish impregnation rate.SOLUTION: In an electric motor stator 10 in which insulating paper 41 and windings 21 are fixed by varnish 31 in slots of a cylindrical stator core 11, when heated to a first temperature, the adhesive strength of adhesives G1, G2 provided on at least one side of a base material 42 of the insulating paper 41 becomes less than the adhesive strength of the varnish 31.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a stator for an electric motor. [Background technology]

[0002] A stator for an electric motor is disclosed in which varnish is permeated into gaps in slots to fix insulating paper and windings to a stator core (see, for example, Patent Document 1). Also, a technique using foam insulating paper as a method for fixing windings is known (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4973420 [Patent Document 2] Patent No. 5497532 Summary of the Invention [Problem to be solved by the invention]

[0004] Because the slots are small spaces, the varnish impregnation rate varies widely, and generally the varnish is so saturated that it overflows from the slots. Large variations in the varnish impregnation rate result in large variations in the adhesive strength (also called bond strength or fixation strength) of the windings, which can make it time-consuming to separate the windings or make them impossible to separate due to the strong adhesive strength. Furthermore, when the slot occupancy rate (the proportion of windings contained within the slot) is high, dismantling by crushing is common. With crushing, the metallic material of the windings is mixed with other materials, resulting in recycling as low-quality material, and making it difficult to recycle the stator core (electromagnetic steel sheet). The present invention has been made in view of the above circumstances, and has an object to provide a stator for an electric motor that is suitable for recycling the windings and stator core without being affected by variations in varnish impregnation rate. [Means for solving the problem]

[0005] The present invention provides a stator for an electric motor in which insulating paper and windings are fixed by varnish within slots in a cylindrical stator core, in which, when heated to a first temperature, the adhesive strength of the adhesive provided on at least one side of the base material of the insulating paper is less than the adhesive strength of the varnish. [Effects of the Invention]

[0006] It is possible to provide a stator for an electric motor that is suitable for recycling the windings and stator core without being affected by variations in the varnish impregnation rate. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a stator for an electric motor according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a cross-sectional structure of insulating paper together with a stator core and windings. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 10 is a diagram schematically illustrating a state of a drawing step in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] [First embodiment] FIG. 1 is a diagram showing a stator for an electric motor according to a first embodiment of the present invention. This electric motor stator 10 is a component that generates a rotating magnetic field, and is a stator used in an electric motor mounted on a vehicle. However, this electric motor stator 10 does not have to be limited to use in a vehicle. Hereinafter, the electric motor stator 10 will be referred to as "stator 10." Stator 10 includes a cylindrical stator core 11 and coils 12 attached to stator core 11. Teeth 11T are provided on stator core 11, protruding inward at intervals in the circumferential direction. Windings 21 are placed in slots formed between adjacent teeth 11T via insulating paper 41, and the insulating paper 41 and windings 21 are fixed to stator core 11 by impregnation with varnish 31 (FIG. 2).

[0010] 1 indicates the axial direction of the stator 10, which coincides with the axial direction of the electric motor. A power distribution component 15 is provided at the end of the winding 21. Generally, the coil 12 corresponds to the winding 21, but in this description, when the coil 12 is separated from the stator core 11 after being assembled to the stator core 11, at least a portion of the insulating paper 41 adheres to the coil 12. Therefore, the insulating paper 41 may also be referred to as a member on the coil 12 side.

[0011] Stator core 11 is formed by laminating electromagnetic steel sheets in axial direction C1. Stator core 11 includes yoke 11A that forms the outer periphery of a cylinder, and teeth 11T that protrude inward from yoke 11A. The winding 21 is bundled into a predetermined shape and placed in each slot formed between the teeth 11T. The winding 21 in this configuration is a so-called SC winding (segment conductor coil) in which a U-shaped conductor is inserted into the slot, with one side closed and the other side open as a segment. Note that the winding 21 is not limited to an SC winding.

[0012] The winding 21 is a wire material in which a metal conductor such as a steel wire, copper wire, or aluminum wire is covered with an insulating coating (hereinafter referred to as an insulating coating). The insulating coating is, for example, an enamel coating. The enamel coating is made of, for example, polyurethane resin, polyester resin, or polyamideimide.

[0013] Varnish 31 is an insulating thermosetting resin that adheres to the windings 21 and other components, and functions as a protective film and fixing material for the windings 21. More specifically, a varnish impregnation process is performed in which varnish 31 penetrates into the gaps in the slots, and the varnish 31 adheres to the windings 21 and other components and hardens. This strengthens the insulating function of coil 12, improves mechanical strength, prevents moisture, dust, and the like from entering the windings 21, and improves heat dissipation. A wide variety of known varnishes can be used as varnish 31.

[0014] Insulating paper 41 is a sheet material having insulating properties and is also referred to as an insulating sheet. By disposing insulating paper 41 between winding 21 and stator core 11, the insulating function between winding 21 and stator core 11 is strengthened.

[0015] FIG. 2 is a diagram showing a cross-sectional structure of insulating paper 41 together with stator core 11 and winding 21. As shown in FIG. As shown in Figure 2, the insulating paper 41 has a multilayer structure consisting of a base material 42 and surface materials 33, 43 that are bonded to both sides of the base material 42 with adhesives G1, G2, respectively. The multilayer structure makes it easier to achieve the desired performance of the insulating paper 41, such as improving its insulation properties, heat resistance, and mechanical strength. For example, the base material 42 is made of a polyamide epoxy alloy sheet material, which has high insulation properties and high heat resistance, and the surface materials 33, 43 are made of aramid paper, which has high strength and high heat resistance. Furthermore, the multilayer structure makes it possible to provide adhesive layers made of adhesives G1, G2 within the insulating paper 41.

[0016] In this description, when distinguishing between adhesives G1 and G2, adhesive G1 located closer to the winding 21 than the substrate 42 will be referred to as "winding-side adhesive G1," and adhesive G2 located closer to the stator core 11 than the substrate 42 will be referred to as "core-side adhesive G2." As shown in Figure 2, varnish 31 is present between the surfaces of stator core 11 and winding 21 and insulating paper 41. Adhesives G1 and G2 have temperature change characteristics that cause their adhesive strength (also referred to as adhesive strength or bonding strength) to decrease at high temperatures. In this configuration, adjustments (selection, component adjustment, etc.) of adhesives G1 and G2 allow them to satisfy the following conditions (1) and (2).

[0017] Adhesion strength at normal temperature T0: Adhesive G1, G2 ≦ Varnish 31 Condition (1) Adhesive strength at temperature TX during withdrawal: Adhesive G1, G2 < Varnish 31... Condition (2)

[0018] The normal temperature T0 is room temperature or the temperature before being heated in the heating process described below. The normal temperature T0 is also a temperature within the temperature range during use of the stator 10 for an electric motor, and can also be referred to as the temperature during use of the electric motor. The temperature TX during extraction is the temperature during the extraction process after heating in the heating process. The heating temperature that reduces the adhesive strength of the adhesives G1 and G2 to less than the adhesive strength of the varnish 31 is temperature T1 (hereinafter referred to as "high temperature T1"). Once the adhesives G1 and G2 are heated to high temperature T1, when the temperature is cooled to normal temperature T0, they return to approximately their original adhesive strength, or they do not return to their original adhesive strength, and the adhesive strength maintains a state where the adhesives G1 and G2 are less than the varnish 31. The temperature TX during extraction may be high temperature T1 or an appropriate temperature after high temperature T1 (for example, normal temperature T0 such as room temperature). Note that even if the varnish 31 is once heated to high temperature T1, when it is cooled to normal temperature T0, the adhesive strength returns to approximately its original adhesive strength. High temperature T1 corresponds to the "first temperature" in this invention, and normal temperature T0 corresponds to the "second temperature" in this invention.

[0019] Incidentally, when recycling this type of stator, it is necessary to dismantle the stator, and conventionally, dismantling by crushing is common. FIG. 3 is a diagram showing the crushing method. Pre-processing shown in step SA is a process carried out before shredding, and involves removing parts that can be removed without shredding. In step SB, shredding and sorting is carried out using a specified shredding machine to shred the stators to be shredded, and then using a specified sorting machine to separate the shredded pieces of windings and shredded pieces of the stator core (electromagnetic steel sheets).

[0020] However, even after sorting, the broken pieces of winding wire contain a large amount of impurities that are different from the metal in the winding wire, and they end up being recycled as low-quality material.Furthermore, crushed pieces of electromagnetic steel sheet also contain materials that are different from electromagnetic steel sheet.At present, recycling of electromagnetic steel sheet is generally difficult.

[0021] When attempting to separate the windings using methods other than the crushing method, it can take a long time to separate the windings of conventional stators due to variations in the adhesive strength of the windings caused by the varnish, or the adhesive strength can be so strong that separation is impossible. In particular, stators for vehicle electric motors are used in environments with severe temperatures and vibrations, so they have a complex structure and the windings are firmly adhered. For this reason, it has been difficult to separate them using methods other than the crushing method.

[0022] In contrast, in this configuration, as described in the above condition (2), the adhesive strength at the temperature TX during extraction is set to "adhesives G1, G2 < varnish," which makes it easier to separate the winding 21 at the adhesives G1, G2, thereby shortening the time required for separation and simplifying the equipment required for separation. Furthermore, as described in the above condition (1), the adhesive strength at normal temperature T0 is set to "adhesives G1, G2 ≦ varnish", so by ensuring that the adhesive strength when used as an electric motor, etc., is at the same level as the adhesive strength of varnish 31, sufficient adhesive strength can be maintained.

[0023] Next, a method for separating the winding 21 from the stator 10 will be described. FIG. 4 is a diagram showing a drawing method for separating the winding 21. In the heating process of step S1, the stator 10 is heated to a predetermined set temperature T2. The set temperature T2 is a temperature at which the stator 10 is heated to a high temperature T1 or above the high temperature T1, which reduces the adhesive strength of the adhesives G1 and G2 to less than the adhesive strength of the varnish 31. The heating process can also be referred to as a baking process, a heating process, a heat treatment process, or the like. In the extraction process, a load F1 is applied to stator 10 to extract winding 21 from stator core 11 in axial direction C1. In stator 10 of this configuration, the adhesive strength during extraction is "adhesives G1, G2 < varnish", so winding 21 can be separated from stator core 11 at either of points K1, K2 (see FIG. 4) of adhesives G1, G2.

[0024] 4, the winding 21 can be separated at either point K1 or K2, so only a portion of the insulating paper 41 remains on the winding 21. Furthermore, after the heating step, whether the adhesives G1 and G2 are kept at their original adhesive strength until they return to their original strength, or the adhesive strength remains such that adhesives G1 and G2 are less than varnish 31, the adhesive strength during removal is "adhesives G1 and G2 < varnish," which prevents the winding 21 from being unable to be separated due to the strong adhesive strength of varnish 31, and requires only a relatively small pulling force F1.

[0025] High temperature T1 is set to a temperature at which the adhesive strength of adhesives G1 and G2 is sufficiently reduced to the point where winding 21 can be pulled out, and load F1 is set to a load appropriate for separating adhesives G1 and G2 at either location K1 or K2. In other words, adhesives G1 and G2 are adjusted or selected so that they have an adhesive strength that allows winding 21 to be pulled out at high temperature T1. Various parameters such as set temperature T2, high temperature T1, temperature TX, load F1, and adhesive strength of adhesives G1 and G2 can be set to appropriate values.

[0026] In a process following step S3, heat is applied to the surface of winding 21 to burn off the insulating coating covering the surface of winding 21. In this case, by applying heat at a high temperature that is sufficient to burn off the insulating coating, the insulating coating can be removed in a short period of time. By removing the insulating coating, it is possible to further reduce the amount of foreign material remaining on the separated winding 21. Therefore, it is possible to further increase the metal ratio on the separated winding 21, which is suitable for recycling.

[0027] As described above, when the stator 10 of this embodiment is heated to high temperature T1 (corresponding to the first temperature), the adhesive strength of the adhesives G1 and G2 provided on both sides of the base material 42 of the insulating paper 41 is less than the adhesive strength of the varnish 31. Therefore, after the stator 10 is heated to high temperature T1, applying a load to pull the winding 21 from the stator core 11 makes it easier to pull the winding 21 from either the adhesive G1 or G2. This makes it easier to separate the winding 21 without being affected by variations in the varnish impregnation rate, and reduces the amount of foreign material remaining on the winding 21 side. As a result, the winding 21 can be recycled as a high-quality material. Furthermore, it is possible to shorten the time required for separation and simplify the equipment required for separation. Furthermore, because the winding 21 can be separated from the stator core 11, recycling of the stator core 11, i.e., recycling of the electromagnetic steel sheet, becomes easier. These features make it possible to provide a stator 10 suitable for recycling the winding 21 and the stator core 11.

[0028] Furthermore, at room temperature or at a normal temperature T0 (corresponding to the second temperature) that corresponds to the temperature before heating, the adhesive strength of the adhesives G1 and G2 on both sides of the substrate 42 is equal to or less than the adhesive strength of the varnish 31. Therefore, when used as an electric motor, the adhesive strength of the adhesives G1 and G2 can be ensured to be approximately the same as that of the varnish 31, and sufficient adhesive strength can be maintained.

[0029] Furthermore, insulating paper 41 has a multilayer structure including substrate 42 and surface materials 33, 43 bonded to both sides of substrate 42. At high temperature T1, the adhesive strength of adhesives G1, G2 between substrate 42 and surface materials 33, 43 is less than the adhesive strength of varnish 31. Therefore, after high temperature T1, winding 21 can be easily separated at adhesives G1, G2, while further reducing the amount of foreign material remaining on the winding 21 side. This also makes it easier to increase the metal ratio on the separated winding 21 side.

[0030] Furthermore, if the stator 10 is a stator used in an electric motor for a vehicle, it is used in an environment that is severe in terms of temperature, vibration, etc., and therefore has a complex structure, and even if the windings, etc. are firmly bonded, by heating to high temperature T1, the windings 21 can be easily separated. Furthermore, a post-process is performed to burn off the insulating coating covering the surface of the winding 21, which further reduces the amount of foreign material remaining on the winding 21 side, thereby increasing the metal ratio on the separated winding 21 side.

[0031] [Second embodiment] The second embodiment differs from the first embodiment in that it satisfies the following condition (3) in addition to condition (1).

[0032] Adhesive strength at temperature TX during withdrawal: Winding side adhesive G1 < Core side adhesive G2 < Varnish 31...Condition (3)

[0033] FIG. 5 is a diagram schematically illustrating a state of the drawing step in the second embodiment. In the second embodiment, by heating the stator 10 to high temperature T1, the adhesive strength of the winding-side adhesive G1 on the base material 42 is less than the adhesive strength of the core-side adhesive G2 on the base material 42, and the adhesive strength of the core-side adhesive G2 is less than the adhesive strength of the varnish 31. The temperature TX during the pulling-out process may be high temperature T1 or an appropriate temperature after high temperature T1 (for example, the same temperature as normal temperature T0). Therefore, as shown in FIG. 5, during the pulling-out process, the winding 21 can be separated from the stator core 11 at the location K1 of the adhesive G1. In this case, compared to when separation occurs at location K2 of core-side adhesive G2, it is possible to avoid a situation in which base material 42 of insulating paper 41 remains on the winding 21 side. Therefore, in the second embodiment, compared to the first embodiment, the amount of foreign material remaining on the winding 21 side can be stably reduced, making it more suitable for recycling winding 21 and stator core 11.

[0034] The above-described embodiments are merely exemplary embodiments of the present invention, and various modifications and applications are possible without departing from the spirit and scope of the present invention. For example, the insulating paper 41 need not be limited to the above structure. For example, the insulating paper 41 may be modified to an appropriate structure as long as it uses either adhesive G1 or G2, and the material of the insulating paper 41 may also be modified as appropriate. Furthermore, while the present invention has been described as being applied to a stator 10 with SC winding specifications, it may also be applied to stators other than those with SC winding specifications. For example, a distributed winding stator may be impregnated with varnish and have the same structure as shown in FIG. 2. Applying the present invention to such a stator makes it easier to separate the winding 21 without being affected by variations in the varnish impregnation rate. Furthermore, the stator 10 is not limited to stators for vehicles such as four-wheeled vehicles and saddle-ride vehicles, but may also be used as a stator for aircraft, ships, and other industrial applications. Furthermore, the stator 10 may be widely used as a stator for rotating electrical machines, including electric motors and generators.

[0035] [Configuration supported by the above embodiment] The above embodiment supports the following configurations.

[0036] (Configuration 1) A stator for an electric motor in which insulating paper and windings are fixed by varnish within slots in a cylindrical stator core, wherein, when heated to a first temperature, the adhesive strength of the adhesive applied to at least one side of the base material of the insulating paper is less than the adhesive strength of the varnish. According to this configuration, after the temperature is raised to the first temperature, applying a load to pull the winding out of the stator core makes it easier to pull out the winding at the adhesive applied to at least one side of the insulating paper base material. This makes it easier to separate the winding without being affected by variations in the varnish impregnation rate, and also reduces the amount of foreign material remaining on the winding side, providing a stator that is suitable for recycling the winding and stator core.

[0037] (Configuration 2) The stator for an electric motor according to Configuration 1, wherein the adhesive strength of the adhesive applied to both sides of the base material is less than the adhesive strength of the varnish when the base material is at the first temperature. This configuration makes it easy to separate the windings at any one of the adhesives provided on both sides of the base material.

[0038] (Configuration 3) A stator for an electric motor according to Configuration 1 or 2, wherein, at the first temperature, the adhesive strength of the winding-side adhesive applied to the winding side of the substrate is less than the adhesive strength of the core-side adhesive applied to the stator core side of the substrate, and the adhesive strength of the core-side adhesive is less than the adhesive strength of the varnish. According to this configuration, after the base material is heated to the first temperature, it becomes easier to separate the windings at the adhesive applied to the winding side of the base material, making it easier to stably reduce the amount of foreign material remaining on the winding side.

[0039] (Configuration 4) A stator for an electric motor according to any one of Configurations 1 to 3, wherein the adhesive strength of the adhesive on both surfaces of the substrate is equal to or less than the adhesive strength of the varnish at room temperature or a second temperature corresponding to the temperature before heating. According to this configuration, the adhesive strength of the adhesive when used as an electric motor can be ensured to the same extent as that of varnish, and sufficient adhesive strength can be maintained.

[0040] (Configuration 5) A stator for an electric motor according to any one of configurations 1 to 4, wherein the insulating paper has a multilayer structure having the substrate and surface materials adhered to both sides of the substrate, and at the first temperature, the adhesive strength of the adhesive between the substrate and the surface materials is less than the adhesive strength of the varnish. According to this configuration, after the base material is heated to the first temperature, the windings can be easily separated at the adhesive on both sides of the base material, and the amount of foreign material remaining on the windings can be more easily reduced.

[0041] (Configuration 6) The electric motor stator according to any one of configurations 1 to 5, wherein the electric motor stator is a stator used in an electric motor for a vehicle. According to this configuration, even in the case of a stator for a vehicle electric motor, which has a complex structure and in which the windings and the like are firmly bonded, the windings can be easily separated by heating to the first temperature. [Explanation of symbols]

[0042] 10... Stator for electric motor, 11... Stator core, 11A... Yoke, 11T... Teeth, 12... Coil, 21... Winding, 31... Varnish, 33, 43... Surface material, 41... Insulating paper, 42... Base material, G1... Winding side adhesive, G2... Core side adhesive, T0... Normal temperature (heating temperature, second temperature), TX... Temperature at time of extraction, T1... High temperature (heating temperature, first temperature), T2... Set temperature, C1... Axial direction

Claims

1. In a stator for an electric motor, insulating paper and windings are fixed by varnish in slots of a cylindrical stator core, When heated to a first temperature, The adhesive strength of the adhesive applied to at least one side of the base material of the insulating paper is less than the adhesive strength of the varnish. Stator for electric motor.

2. At the first temperature, The adhesive strength of the adhesive applied to both sides of the substrate is less than the adhesive strength of the varnish.

2. The stator for an electric motor according to claim 1.

3. At the first temperature, The adhesive strength of the winding-side adhesive applied to the winding side of the substrate is less than the adhesive strength of the core-side adhesive applied to the stator core side of the substrate, and the adhesive strength of the core-side adhesive is less than the adhesive strength of the varnish.

2. The stator for an electric motor according to claim 1.

4. At room temperature or a second temperature corresponding to the temperature before heating, The adhesive strength of the adhesive on both sides of the substrate is equal to or less than the adhesive strength of the varnish. The stator for an electric motor according to any one of claims 1 to 3.

5. the insulating paper has a multilayer structure including the base material and surface materials bonded to both sides of the base material; At the first temperature, the adhesive strength between the substrate and the surface material is less than the adhesive strength of the varnish. The stator for an electric motor according to any one of claims 1 to 3.

6. The electric motor stator is a stator used in an electric motor for a vehicle. The stator for an electric motor according to any one of claims 1 to 3.

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