JP2007215334A - Stator for motor, and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator for motor which can efficiently release the heat generated within a coil without using a conventional insulator via a cover layer made on the surface of the core. <P>SOLUTION: This stator 2 for motor is made by winding a coil 6 on the core 3 made of magnetic substance. It is equipped with a cover layer 5 made of the surface of the above core, which has heat conductivity and electric insulation, and a coil body 7 which is made by winding the above coil 6 around the above cover layer 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stator for an electric motor. Specifically, the present invention relates to a stator for an electric motor provided with a coating layer having thermal conductivity and electrical insulation instead of a resin insulator provided between a winding body and a core.

  In hybrid vehicles and electric vehicles, an electric motor is used to drive the vehicle. This drive motor is required to be small in size and light in weight as well as high output and high efficiency. For this reason, weight reduction and downsizing in units of grams and millimeters are required without reducing the output.

  In an electric motor, a winding body (coil) is formed by winding a winding around a core of a stator. However, in order to realize further downsizing at a high output, the space of the winding body such as a stator is increased. It is required to improve the rate to the limit. Also, a large current is passed through the windings to increase the magnetic force and obtain a large output.

  However, when a large current flows, the amount of heat generated due to the resistance of the winding increases, and the amount of heat generated per unit volume increases as the space factor increases. Heat generated in the windings is transmitted across adjacent windings, part of the heat is dissipated from the outer layer of the winding body, and part of the heat is transferred to the core via the insulator to dissipate heat on the outer periphery of the stator. Heat is dissipated from the parts. Further, the heat is transmitted in the axial direction of the winding and is also radiated from the introduction portion (coil end portion) of the winding.

  The outer layer part of the winding body and the outer peripheral part of the core are configured to be cooled with a cooling medium, but heat generated inside the winding body is transferred to the outer peripheral part of the winding body and the core. If it cannot escape efficiently, the temperature inside the winding body will rise.

  On the other hand, a cylindrical resin insulator is attached to the core in order to ensure electrical insulation. Although the core is made of metal and has high thermal conductivity, the resin insulator has low thermal conductivity and prevents heat generated inside the winding from being radiated to the core. For this reason, heat is trapped inside the winding body and the temperature rise is likely to increase. When the temperature inside the winding body rises, it adversely affects the insulation coating of the windings and lowers the insulation performance, and further leads to a reduction in the output and life of the motor.

  In order to solve the above problems, a structure in which the insulator is formed using a highly heat conductive member has been proposed.

JP 2001-128402 A

  In the invention described in the above patent document, a part of the insulator is replaced with a high thermal conductor. That is, the insulator described in the above-mentioned patent document is provided with a hole for arranging the high thermal conductor, and a metal plate or a resin sheet having a high thermal conductivity is fitted into the hole. The metal plate and the resin sheet are pressed against the core surface exposed from the hole portion by the pressure acting from the inner peripheral portion of the winding, so that the grounding with the core can be ensured and heat conduction can be enhanced.

  However, in the configuration of the above-mentioned patent document, the amount that the high heat conductor can be deformed by the pressure acting from the inner peripheral portion of the winding body is limited. Therefore, it is clear that a gap along the winding is formed between the inner periphery of the winding body and the high thermal conductor. For this reason, many of the uneven surfaces generated by winding of the winding cannot be brought into contact with the high thermal conductor. Therefore, heat cannot be efficiently conducted from the winding body to the high thermal conductor.

  Further, a part of the high thermal conductor is exposed to the outside of the insulator from the hole, and the pressure is applied from the inner periphery of the winding body. It is not considered that a uniform pressure acts on the high heat conductor. Therefore, the high heat conductor cannot be uniformly adhered to the core surface with sufficient pressure, and heat cannot be efficiently conducted from the high heat conductor to the core surface.

  In order to increase the thermal conductivity to the core, it is desirable to make the insulator as thin as possible. However, since the insulator is formed by injection molding of resin, a certain degree of strength is required at the time of molding or mounting on the core. Therefore, there is a limit to reducing the thickness of the insulator.

  Moreover, in the configuration of the above-mentioned patent document, it is obvious that the manufacturing operation or the mounting operation is very troublesome because a hole is formed in the insulator and the high heat conductor is inserted into the hole.

  This invention solves the said problem, and makes it a subject to provide the stator for motors which can make the said core generate | occur | produce efficiently the heat | fever which generate | occur | produced inside the winding body, without using the conventional insulator. .

  The present invention is a stator for an electric motor formed by winding a winding around a core formed of a magnetic material, and a coating layer having thermal conductivity and electrical insulation formed on the core surface; And a winding body formed by winding the winding around the coating layer.

  The coating layer can be formed by directly applying a coating material on the core surface. For this reason, the thickness of the said coating layer is remarkably small compared with the conventional insulator, and can hold | maintain the inner peripheral part of a winding body close to the core surface. Therefore, even if the coating layer has a thermal conductivity equivalent to that of a conventional insulator, the thermal conductivity is improved by a reduction in thickness. Moreover, as a result of being able to hold the inner periphery of the winding close to the surface of the core, the space factor of the winding is also improved.

  Moreover, the coating layer is formed to have high thermal conductivity and electrical insulation. As a result, it is possible to remarkably increase the amount of heat conducted from the inner periphery of the winding body to the core while ensuring electrical insulation, and it is possible to extremely effectively prevent the temperature inside the winding body from rising.

  The coating layer can be formed using various materials as long as the winding body can be wound around the outer periphery and high thermal conductivity and electrical insulation can be secured.

  For example, as described in claim 2, the coating layer can be formed from a resin containing an inorganic filler. Various resin materials can be employed as long as they can withstand the heat generation temperature of the winding body and have shape retention at the use temperature. For example, as in the invention described in claim 3, at least one of a polyimide resin and a polyamide-imide resin can be adopted as the resin material constituting the coating layer.

  Moreover, the said filler is an insulating material, Comprising: The thing whose heat conductivity is higher than the resin material with which this is mix | blended is employ | adopted. For example, as in the invention described in claim 4, it is preferable to employ at least one of silica and alumina as the inorganic filler.

  The mixing ratio of the resin material and the inorganic filler is not particularly limited as long as the winding can be wound and the required strength and durability can be ensured when the motor is operated. The resin coating layer, as in the invention described in claim 16, is a coating step of coating the core surface with a coating material to be investigated by adding the inorganic filler in an organic solvent solution of the resin; It can be formed including an organic solvent removing step for removing the organic solvent.

  As in the invention described in claim 5, the coating layer can be configured to include at least a plurality of layers having different mechanical characteristics. Various layers with different mechanical properties can be provided to increase thermal conductivity and electrical insulation and to securely hold the windings around the core. For example, in order to achieve the above object, coating layers having different mechanical strength, deformation characteristics, heat resistance, adhesion characteristics, and the like can be formed.

  That is, since the winding is wound around the outer layer, there is a risk of damaging the winding during the winding work or the like unless there is a certain degree of deformability, and the adhesion between the winding and the coating layer is obtained. I can't do that either. On the other hand, the covering layer can reliably hold the winding body as a whole, and should not have dielectric breakdown or the like. For this reason, it is preferable to form a plurality of layers having different mechanical characteristics on the winding side and the core side.

  According to a sixth aspect of the present invention, the covering layer includes an inner layer formed on the core surface and an outer layer formed on the inner layer, and the inner layer is a machine higher than the outer layer. It is preferable to set so as to provide the desired strength.

  For example, by increasing the blending ratio of the inorganic filler, an inner layer with improved electrical insulation and mechanical strength, and an outer layer that functions as a protective layer for the windings with a polyamideimide resin having self-lubricating performance are formed. be able to.

  Moreover, like the invention described in claim 7, the outer layer can also function as an adhesive layer having high thermal conductivity and adhesiveness.

  In general, if the blending ratio of the filler is increased, not only thermal conductivity and electrical insulation properties but also mechanical strength is improved. That is, as in the invention described in claim 8, by setting the filler blending ratio of the inner layer larger than the filler blending ratio of the outer layer, the mechanical strength of the inner layer is set larger than the mechanical strength of the outer layer. can do. However, when an excessive amount of filler is blended, brittleness may appear and cracks may occur. In addition, the effect which prevents generation | occurrence | production of the said crack can be anticipated by providing the said outer layer with resin softer than the said inner layer.

  Further, as described in claim 9, by forming the inner layer and the outer layer using different resin materials, it is possible to form layers having not only mechanical strength but also mechanical properties such as deformability. it can.

  The coating layer is not limited to one using a resin material. According to a tenth aspect of the present invention, the coating layer can be composed of an inorganic fired layer in which an inorganic material is fired and adhered to the core surface.

  For example, the inorganic fired layer can be formed of an insulating ceramic such as silicon carbide or silicon nitride, or a crystalline glass ceramic. When the members constituting the core and the coating layer have different thermal expansion coefficients, a stress relaxation layer such as a soft metal can be provided.

  The inorganic fired layer is generally hard. For this reason, if the winding is wound directly around the inorganic fired layer, the winding may be damaged. Further, as it is, the contact area of the winding with the coating layer is small. In this case, as in the invention described in claim 11, it is preferable to form an outer layer made of a highly heat conductive resin containing an inorganic filler on the outer surface of the inorganic fired layer. More preferably, the outer layer may function as an adhesive layer for the inner periphery of the winding. With this configuration, heat can be efficiently released from the winding to the covering layer or the core.

  In the present invention, the winding is wound around a coating layer that is substantially integrated with the core. Therefore, it is preferable to mold the core itself and the coating layer into a shape suitable for winding the winding.

  For example, as in the invention described in claim 12, winding grooves corresponding to the cross-sectional shape of the winding can be provided on the core surface or the coating layer. By providing the winding groove, the winding can be wound with high accuracy and the space factor is improved. In addition, the inner periphery of the winding body can be held closer to the covering layer or the core.

  The method for forming the winding groove is not particularly limited. When the core is formed by a powder metallurgy method, the winding groove can be formed when the powder material is compression-molded.

  Moreover, after the coating material which comprises a coating layer is applied, the said winding groove | channel can be formed by pressing the template etc. corresponding to the said winding groove | channel.

  Furthermore, as in the invention described in claim 13, it is possible to form a curved surface on which the winding can be directly wound around the corner where the winding of the core is wound.

  With this configuration, the winding can be protected by the shape of the core itself, and the winding protection function of the conventional insulator can be replaced. Further, unnecessary stress or the like is not generated in the winding body, and the thickness of the coating layer can be reduced. As a result, the heat conduction performance of the coating layer can be enhanced, and the space factor can be further improved. The said form of a core can add the said shape in a shaping | molding step, when forming a core with a metal powder metallurgy method.

  The present invention can be applied to various stators. For example, as described in claim 14, the coating layer can be formed on the core of each divided stator that is assembled in an annular shape and constitutes the stator. Thereby, a small and high output electric motor can be manufactured.

  As shown in FIG. 1, in the present embodiment, the present invention is applied to each divided stator 2 of a concentrated winding stator 1 for an electric motor configured by annularly combining a plurality of divided stators each provided with a winding body. It is applied.

  The stator 1 is assembled by assembling a plurality of split stators 2 in an annular shape, and then enclosing and fixing them from the outside using a ring member (not shown). An electric motor is configured by disposing a rotor (not shown) provided with permanent magnets inside the stator 1. FIG. 1 shows a cross section perpendicular to the axis of the annular stator so that the overall structure of the stator 1 composed of the split stator 2 can be understood.

  FIG. 2 shows a cross section of each split stator 2. The split stator 2 is formed by winding a winding 6 around a ferromagnetic core 3 formed by sintering powder metal after compression molding, and a tooth portion 4 of the core 3. And a body 7.

  In the conventional stator, the winding 6 is wound through the insulator to form the winding body 7. The insulator is provided mainly for securing electrical insulation, but at the same time has a function of protecting the winding wound around the insulator.

  On the other hand, in the present invention, the insulator is not mounted, and the winding 6 is wound around the core 3 through the coating layer 5 that is much thinner than the insulator. For this reason, there exists a possibility of damaging a coil | winding in the shape of the conventional teeth part.

  In order to avoid the above problem, in the present embodiment, the corner portion 8 of the tooth portion 4 is formed in a curved shape corresponding to the outer surface shape of the winding 6, and the winding 6 is damaged at the corner. It is preventing.

  FIG. 3 shows a cross section taken along line III-III in FIG. As shown in this figure, the corner 9 of the cross section around which the winding 6 is wound is also formed in a curved surface having a large radius of curvature, and the winding 6 wound around this is prevented from being damaged. Yes. Further, in this embodiment, by forming the outer surface of the tooth portion 4 in a stepped shape, the windings 6 wound around the teeth portion 4 can be arranged without a gap so that the space factor can be improved. It is composed. Each shape of the above-mentioned teeth part 4 can be given at the time of compression molding of powder.

  The covering layer 5 is formed with a substantially uniform thickness corresponding to the surface form of the tooth portion 4. And the said coil | winding 6 is wound by the teeth part 4 through the said coating layer 5, and the winding body 7 is formed.

  The coating layer 5 is formed by blending a resin solution obtained by dissolving a resin material in a solvent with a filler having high thermal conductivity to form a coating material, and coating the coating material on the surface of the tooth portion 4. It can be formed by removing.

  What is necessary is just to employ | adopt what has the heat resistance with respect to the temperature which generate | occur | produces at the said winding body 7 at least as the said resin material, For example, a polyimide resin, a polyamideimide resin, etc. are employable. Specifically, a high melt series 7375 of a jet melt adhesive manufactured by Sumitomo 3M Co., Ltd. is adopted as the resin material, and a filler such as alumina or silica is blended therein to constitute the resin coating material. it can.

  The inorganic filler is preferably made of silica or alumina in order to ensure high thermal conductivity and electrical insulation. By blending the inorganic filler with the resin material, not only the heat conduction performance is improved, but also the mechanical strength when the coating layer is formed is improved, and the winding body can be reliably held.

  FIG. 4 shows a first embodiment of the coating layer. In this figure, the thickness of the covering layer 5 is greatly shown for easy understanding.

  As shown in FIG. 4, the inner peripheral portion of the winding body 7 is held in contact with the coating layer 5. Since the coating layer 5 has high thermal conductivity, heat can be conducted from the inner peripheral portion of the winding body 7 toward the core. Thereby, it is possible to prevent the internal temperature of the winding body 7 from rising. In addition, since the coating layer 5 is based on the resin described above, it can be elastically or plastically deformed to some extent even when the winding is wound after curing. For this reason, it can be expected that the surface of the coating layer is deformed corresponding to the outer surface of each winding 6 and the contact area of the winding 6 with the coating layer 5 is increased. And since the said coating layer 5 is very small compared with the conventional insulation, thermal conductivity increases markedly.

  The winding can be wound after the coating material is completely cured, or the winding 6 can be wound in a state where the coating material is not completely cured. By winding the winding 6 in a state where the coating layer 5 is not completely cured, a winding body can be formed with a portion of the winding embedded in the coating layer 5. If comprised in this way, the contact area with respect to the coating layer 5 of the coil | winding 6 will increase, and thermal conductivity will also become large. Further, since the winding body 7 is bonded and fixed to the core 3 through the coating layer 5, deformation and movement of the winding body 7 can be prevented. Further, it is possible to prevent the coating layer of the winding 6 from being damaged.

  FIG. 5 shows a second embodiment of the coating layer.

  In this embodiment, the coating layer 5 includes an outer layer 5A that contacts the inner peripheral portion of the winding body 7 and an inner layer 5B that is formed on the surface of the tooth portion 4 of the core. The outer layer 5A is configured to be brought into contact with the winding body 6 and to support pressure acting from at least the inner periphery of the winding body. The outer layer 5A only needs to support the pressure and hold the winding body 7, and a certain degree of deformation is allowed. On the other hand, the inner layer 5B has higher mechanical strength than the outer layer 5A, and is formed so that the winding body 7 can be prevented from contacting the surface of the core 3.

  Since the filler has a lower deformability than the resin material, the hardness of the covering material increases as the proportion of the filler increases. Further, as the amount of filler added increases, the thermal conductivity and electrical insulation properties also improve. Therefore, the mechanical strength of the inner layer 5B can be increased by making the blending ratio of the inorganic filler to the forming material of the inner layer 5B larger than the blending ratio of the forming material of the outer layer 5A. On the other hand, if the amount of filler added is too large, brittleness appears and cracks and the like are likely to occur. Further, when the hardness is increased, the winding may be damaged.

  In this example, in order to alleviate the above problem, the outer layer 5A is formed in which the blending ratio of the filler is smaller than that of the inner layer 5B. The outer layer 5A is easily deformed compared to the inner layer 5B because the blending amount of the filler is small. Therefore, it is well adapted to the inner peripheral part of the winding body 7, the contact area is increased, and the adhesion is improved. As a result, the thermal conductivity of the entire coating layer can be increased.

  Furthermore, the outer layer 5A can be an adhesive layer that has high thermal conductivity and adhesiveness, and improves the adhesion between the winding 6 and the inner layer 5B. Specifically, after the inner layer 5B is cured, the coating material of the outer layer 5A is applied, and the winding body 7 is wound through the outer layer 5A by winding the winding 6 while it is not cured. The core 3 is bonded and fixed. Thereby, the inner peripheral part of the coil | winding 6 is firmly fixed to the core 3, and thermal conductivity is also improved.

  The mechanical strength of the outer layer 5A and the inner layer 5B can be adjusted not only by changing the blending amount of the filler but also by using different types of resin materials. For example, a resin material having higher hardness and mechanical strength than the resin material employed for the outer layer 5A may be employed for the inner layer 5B.

  Furthermore, in the present invention, an inorganic fired layer can be adopted as the coating layer 5. The inorganic fired layer is formed by firing and attaching an inorganic material to the core surface. As a material constituting the upper inorganic fired layer, for example, an insulating ceramic such as silicon carbide or silicon nitride, or a crystalline glass ceramic can be employed.

  The ceramic fired layer is harder than the metal constituting the core 3 and has a low thermal expansion coefficient. For this reason, there exists a possibility that a thermal stress may generate | occur | produce in a boundary layer. In order to alleviate the above problem, a stress relaxation layer such as a soft metal can be provided between the surface of the core 3 and the fired layer.

  FIG. 6 shows a third embodiment of the coating layer. In this embodiment, a winding groove 11 corresponding to the cross-sectional shape of the winding 6 is provided on the surface of the tooth portion 4 of the core, and a coating layer 5C having a substantially uniform thickness is provided on the surface of the winding groove 11. ing. By adopting this configuration, the contact area between the inner periphery of the winding 6 and the surface of the core 3 can be increased. Moreover, it becomes possible to make the metal which comprises the core 3, and the said coil | winding 6 close further, and thermal conductivity further improves.

  The winding groove 11 can be formed using various methods. For example, if a core formed by sintering metal powder is employed, it can be added at the powder forming stage. Moreover, the said winding groove | channel 11 can also be formed by machining etc. after shaping | molding.

It is a figure which shows the whole structure of the stator of this invention. It is sectional drawing of the division | segmentation stator which comprises the stator shown in FIG. It is sectional drawing which follows the III-III line | wire in FIG. It is a figure which shows 1st Embodiment of a coating layer, and is an expanded sectional view which shows the state by which the winding body is hold | maintained at the coating layer. It is a figure which shows 2nd Embodiment of a coating layer, and is an expanded sectional view which shows the state by which the winding body is hold | maintained at the coating layer. It is a figure which shows 3rd Embodiment of a coating layer, and is an expanded sectional view which shows the state by which the winding body is hold | maintained at the coating layer.

Explanation of symbols

2 Stator 3 Core 5 Coating layer 6 Winding 7 Winding body

Claims (16)

A stator for an electric motor formed by winding a winding around a core formed of a magnetic material,
A coating layer having thermal conductivity and electrical insulation formed on the core surface;
A stator for an electric motor, comprising: a winding body formed by winding the winding around the covering layer.   The stator for an electric motor according to claim 1, wherein the coating layer is formed of a resin containing an inorganic filler.   The stator for an electric motor according to claim 2, wherein the resin is at least one of a polyimide resin and a polyamideimide resin.   The stator for an electric motor according to any one of claims 2 and 3, wherein the inorganic filler is at least one of silica and alumina.   The stator for an electric motor according to any one of claims 1 to 4, wherein the covering layer includes at least a plurality of layers having different mechanical characteristics. The coating layer is configured to include an inner layer formed on the core surface and an outer layer stacked on the inner layer,
The stator for an electric motor according to claim 5, wherein the inner layer is configured to have higher mechanical strength than the outer layer.   The stator for an electric motor according to claim 6, wherein the outer layer is an adhesive layer that has high thermal conductivity and adhesiveness, and increases adhesion between the winding and the inner layer.   The stator for an electric motor according to any one of claims 6 and 7, wherein a filler compounding amount of the inner layer is set larger than a filler compounding amount of the outer layer.   The inner layer and the outer layer are formed using different resin materials, and the mechanical strength of the resin material adopted for the inner layer is higher than the mechanical strength of the resin material adopted for the outer layer. Item 9. The stator for an electric motor according to any one of Items 8.   The stator for an electric motor according to claim 1, wherein the coating layer is an inorganic fired layer in which an inorganic material is fired and adhered to the core surface.   The stator for an electric motor according to claim 10, wherein an outer layer made of a highly heat conductive resin containing an inorganic filler is formed on an outer surface of the inorganic fired layer.   The stator for an electric motor according to any one of claims 1 to 11, wherein a winding groove corresponding to a cross-sectional shape of a winding is provided on the core surface or the coating layer.   The stator for an electric motor according to any one of claims 1 to 12, wherein a curved surface capable of directly winding the winding is formed at a corner portion where the winding of the core is wound.   The stator for an electric motor according to any one of claims 1 to 13, wherein the coating layer is formed on a core of each divided stator that is assembled in a ring shape and constitutes the stator.   An electric motor provided with the stator for electric motors described in any one of Claims 1-14. A method for manufacturing a stator for an electric motor in which a resin coating layer having thermal conductivity and electrical insulation is provided on the surface of a core formed of a magnetic material and wound with a winding,
A coating step of coating the surface of the core with a coating material prepared by adding the inorganic filler to the organic solvent solution of the resin;
The manufacturing method of the stator for electric motors including the organic solvent removal process of removing the said organic solvent.

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