JP2012029492A - Electric motor and method for manufacturing electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor that prevents negative effects of heat on the electric motor and its surrounding components.SOLUTION: An electric motor includes: a stator (20) with a coil (22) wound thereon; a rotor (30) provided on an inner circumferential side of the stator (20); and a housing (41) that stores the stator (20) therein, supports the rotor (30) in a rotatable manner, and has a coolant passage (41a) through which a coolant passes. The housing (41) has a high radiation coating with high radiation properties formed at an interface with an internal space defined by the housing (41). Heat evolved from the coil (22) and the rotor (30) is transferred to the housing (41) through the high radiation coating.

Description

  The present invention relates to an electric motor for preventing the influence of heat on an electric motor and its peripheral components, and a method for manufacturing the electric motor.

  An electric motor (electric motor) rotates by converting electric energy into kinetic energy. At this time, a part of the electric energy is converted into heat energy to generate heat. Inside the electric motor, heat is generated from the rotor and coils. If this heat is not appropriately processed, the efficiency of the electric motor may be deteriorated due to the influence of heat, or the components arranged around the electric motor may be affected by the heat.

  As a countermeasure against heat inside the electric motor, heat conduction and heat dissipation coating with properties that combine high thermal conductivity, high heat dissipation and high insulation on the surface of the coil body, the inner surface of the motor chassis, and the outer surface of the motor chassis It is known that a film is provided, the heat generated by the coil body is transmitted to the motor chassis through the heat conducting / heat dissipating coating film, and heat is radiated from the motor chassis to the outside (see Patent Document 1).

JP 2009-153366 A

  The electric motor described in Patent Document 1 includes a thermally conductive and heat-dissipating coating film that also serves as an insulating film on the surface of the coil body. Further, the heat conduction / heat radiation coating film on the surface of the motor chassis is configured to radiate heat from the surface of the electric motor to the outside. In such a configuration, there is a problem in that other components arranged in the vicinity receive heat due to heat radiated from the surface of the electric motor, and the temperature of the components rises.

  In particular, in a vehicle (EV, HEV) equipped with an electric motor, since the space around the electric motor is limited, other components and the electric motor have to be arranged close to each other, and the influence of heat reception is great.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an electric motor that prevents the influence of the electric motor and the surrounding heat by appropriately processing the heat of the electric motor. To do.

  According to an embodiment of the present invention, a stator around which a coil is wound, a rotor provided on the inner peripheral side of the stator, a stator is housed, the rotor is rotatably supported, and the coolant is circulated. An electric motor comprising a housing having a path is configured. The housing is characterized in that a high radiation coating having high radiation characteristics is formed at the interface with the internal gap formed by housing, and heat generated from the stator and the coil is transferred to the housing through the high radiation coating. .

  According to the present invention, the heat from the rotor and the coil that generates heat when the electric motor is driven is radiated into the air gap inside the electric motor, and this radiant heat is transmitted to the housing by the high radiation coating having high radiation characteristics. can do. The heat transferred to the housing can be released to the outside by the coolant. With such a configuration, the electric motor can be cooled while preventing the heat generated by the electric motor from affecting the components around the electric motor.

It is sectional drawing of the electric motor of the 1st Embodiment of this invention. It is a table | surface which shows an example of the highly radiation coating of the 1st Embodiment of this invention. It is explanatory drawing which measured the effect by the high radiation surface treatment in the stator of the 1st Embodiment of this invention. It is explanatory drawing which measured the effect by the high radiation surface treatment in the rotor of the 1st Embodiment of this invention. It is explanatory drawing which shows the relationship between the film thickness of the high radiation coating of the 1st Embodiment of this invention, and a radiation rate. It is sectional drawing of the electric motor of the 2nd Embodiment of this invention. It is sectional drawing of the electric motor of the 3rd Embodiment of this invention.

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

<First Embodiment>
FIG. 1 is a cross-sectional view of an electric motor 10 according to a first embodiment of the present invention.

  In the electric motor 10, the rotor 30 housed inside the stator 20 is rotated by a magnetic field generated by passing a current through the stator 20.

  The stator 20 is housed in a substantially cylindrical housing 41 and is fixed in contact with the housing 41.

  The stator 20 is configured by stacking a plurality of stator cores 21 made of electromagnetic steel plates in the axial direction.

  The stator 20 is formed with a plurality of groove-like slots (not shown) in the circumferential direction, and each slot is made of a copper enamel wire made up of a U-phase coil group, a V-phase coil group, and a W-phase coil group. A coil 22 is wound.

  A pair of coil ends 23 (23 a, 23 b) are formed at ends in the axial direction of the stator 20, with the coils 22 exposed from the stator core 21.

  The coil end 23 is subjected to a coil lacing process and a varnish filling process. The coil lacing process is a process in which after insulating paper is sandwiched between the coils 22, the insulating paper is suppressed and the coil 22 is bound with heat-resistant yarn. This process ensures insulation between the copper wires of the coil 22 and prevents the enamel of the conductive wire from being worn by vibration.

  The varnish filling process is a process of filling the coil 22 and the coil end 23 inside the stator 20 with a varnish having high thermal conductivity after the coil racing process. This process increases the thermal conductivity of the stator 20 and prevents vibration of the coil 22 to prevent enamel wear. As the varnish, for example, an amide-imide ester resin is used.

  The rotor 30 is configured by laminating a plurality of rotor cores 32 made of electromagnetic steel plates around an axis of rotation 31 in the axial direction. The rotor core 32 has a plurality of slots (not shown) formed in the circumferential direction, and a magnet 33 is fixed to the slots. A pair of end plates 34 (34a, 34b) for fixing the rotor core 32 are provided at the axial end of the rotor core 32.

  The housing 41 has a plurality of holes formed inside the wall, and a cooling liquid passage 41a is formed by circulating the cooling liquid through the holes. The coolant is exchanged between the housing 41 and the coolant by allowing the coolant to flow through the coolant channel 41a of the housing 41. Thereby, the heat generated by the electric motor 10 is released to the outside of the electric motor 10. For example, LLC (Long Life Coolant) is used as the coolant.

  The housing 41 includes a cylindrical barrel portion 43 that covers the periphery of the stator 20 and a pair of brackets 42 (42 a, 42 b) that close the axial opening of the barrel portion 43. The rotating shaft 31 of the rotor 30 is rotatably supported by the bracket 42 via a pair of bearings 35 (35a, 35b). The bearing 35 is constituted by a bearing, for example.

  The body 43 and the bracket 42 of the housing 41 are both formed of a metal material such as an aluminum alloy. Accordingly, the heat received by the body 43 and the bracket 42 is quickly transmitted and cooled by the coolant.

  Next, the heat dissipation structure of the electric motor 10 configured as described above will be described.

  The electric motor 10 generates a magnetic field when current is applied to the coil 22 of the stator 20, and heat is generated as a loss. The rotor 30 obtains kinetic energy by a magnetic field and generates heat as a loss.

  If the heat generated in the electric motor 10 is not appropriately processed, not only the temperature of the electric motor 10 rises and the operation efficiency is lowered, but also there is a possibility of affecting the components arranged around the electric motor 10.

  Since the coolant flows through the housing 41, the housing 41 itself is always cooled. As a result, the stator 20 in contact with the housing 41 is cooled. On the other hand, the coil end 23 projecting from the stator 20 and the rotor 30 located away from the stator 20 are not in contact with the housing 41, so that heat is not directly transferred. Therefore, it is necessary to appropriately process the heat of the coil end 23 and the rotor 30.

  In the present embodiment, the configuration described below is configured to easily transfer the heat generated in the electric motor 10 to the outside and cool the electric motor 10 appropriately.

  The electric motor 10 of the present embodiment is subjected to a high radiation surface treatment in which a high radiation film is formed in order to efficiently transfer the heat of the coil end 23 and the rotor 30 to the housing. More specifically, the surface of the housing 41 facing the coil end 23 and the rotor 30 was subjected to a high radiation surface treatment in which a high radiation coating was formed. In addition, in FIG. 1, the location which performed the high radiation surface treatment is shown with a dotted line.

  The highly radiant surface treatment is a treatment in which the efficiency of radiating heat (infrared rays) to the outside (and the efficiency of absorbing heat from the outside) is increased. As an example of high radiation surface treatment, by forming a coating film in which one or more kinds of particles exhibiting high radiation characteristics such as metal oxide, carbon black, silicon carbide, etc. are dispersed in an epoxy resin or acrylic resin material Composed. Or it comprises by forming an amide imide ester type | system | group film | membrane.

  FIG. 2 is a table showing an example of the highly radiant coating used in the highly radiant surface treatment of the present embodiment.

In addition, the analyzer and measurement conditions shown in FIG. 2 are as follows.
Analyzing device (infrared spectrophotometer (FT-IR)): JEOL Fourier transform infrared spectrophotometer JIR-5500 type / infrared radiation unit IR-IRR200
Standard blackbody furnace: 40 and 80 ° C. or 80 and 160 ° C. (two-point temperature standard calibration method)
Measurement temperature: 80 ° C
Detector: MCT (measurement wavelength range: 4.5 to 20 μm)
Resolution: 16cm ^-1
Integration count: 500 times

  Each of the films has an emissivity of about 0.9, which is a value close to 1 which is an ideal black body radiation, and indicates that the efficiency of radiating heat (infrared rays) is high. Moreover, since the absorption rate of heat (infrared rays) is equal to the emissivity, the heat radiated from the outside can be efficiently received by performing such a high radiant surface treatment using the high radiant film. .

  As indicated by arrows in FIG. 1, heat generated from the coil end 23 and the rotor 30 due to the high radiation surface treatment causes the inner surface of the stator 20, the inner surface of the housing 41, and the inner surface of the bracket 42 through the space inside the electric motor 10. Communicate to. Since the stator 20, the housing 41, and the bracket 42 are each made of metal, the heat transmitted to the stator 20 and the bracket 42 is easily transmitted to the housing 41.

  Since the coolant flows through the housing 41, heat is transferred to the outside by exchanging heat with the coolant. As a result, the heat generated in the electric motor 10 is released to the outside by the coolant.

  The high radiation surface treatment in the electric motor 10 is formed by the following process when the electric motor 10 is assembled.

  First, the stator 20 is inserted into the body 43 of the housing 41. The stator 20 is wound with a coil 22 and has already been subjected to a coil lacing process and a varnish filling process.

  Next, a high radiation coating is formed on each of the body portion 43, the stator 20, and the bracket 42 at the interface with the internal gap formed by the housing 41. The high radiation coating is formed by applying the resin material as described above to these interfaces, followed by drying and baking.

  After the high radiation coating is formed, the already assembled rotor 30 is inserted into the inner periphery of the stator 20, and the rotating shaft 31 of the rotor 30 is gripped by the bearing 35 press-fitted into the bracket 42. Then, the bracket 42 is fixed to the trunk portion 43 with bolts or the like.

  The electric motor 10 is subjected to a high radiation surface treatment through the processes as described above.

  Next, the experimental result of the effect in the electric motor 10 of this embodiment is shown. In addition, the experimental results shown in FIGS. 3 to 5 used Cooltech (emissivity 0.92 at a film thickness of 30 μm) manufactured by Okitsumo Co., Ltd. shown in FIG. 2 as the high radiation surface treatment.

  First, the experimental result of the heat dissipation of the stator 20 will be described.

  FIG. 3 is an explanatory diagram in which the effect of the high radiation surface treatment is measured in an experimental apparatus using the stator 20 that is a component of the electric motor 10 of the present embodiment.

  As shown in FIG. 3A, the experimental apparatus is obtained by removing the rotor 30 from the electric motor 10. That is, the stator 20 is housed in the housing 41, and both ends of the housing 41 are closed by the brackets 42a and 42b.

  In such an experimental apparatus, the temperature of the coil end 23 was measured when the coil 22 was energized with respect to each of the metal substrate that was not subjected to the high radiation surface treatment and the metal substrate that was subjected to the high radiation surface treatment. Further, the thermal resistance from the coil end 23 to the cooling water at that time was measured.

  The power supplied to the coil 22 is 500 [W], 1000 [W], and 1500 [W], and the coolant is a water temperature 60 [° C.] and a flow rate 15 [l / min] by a pump with a temperature control function (not shown). It was circulated.

The thermal resistance R _th was calculated by the following formula (1).

R _th = Q / (T _coil −T _water ) (1)
Here, Q is the power supplied to the _coil , T _coil is the temperature of the coil end 23, and T _water is the temperature of the coolant.

With respect to the thermal resistance _Rth calculated in this way, the temperature of the coil end 23 of the stator 20 that has been subjected to the high radiation treatment is compared with the stator 20 that has not been subjected to the high radiation treatment for each of the electric energy that has passed through the coil 22. FIG. 3 (B) shows the ratio of whether or not it has been reduced. The percentage is expressed in percentage as the temperature reduction rate.

Referring to the result shown in FIG. 3B, the thermal resistance R _th between the coil end 23 and the coolant is approximately 1 to 1 by applying a high radiation surface treatment to the surface facing the coil end 23. It became clear that it was reduced by about 3%.

  Therefore, it was confirmed that the heat dissipation of the coil end 23 can be improved by the high radiation surface treatment.

  Next, the experimental result of the heat dissipation of the rotor 30 will be described.

  FIG. 4 is an explanatory diagram in which the effect of the high radiation surface treatment on the rotor 30 is measured in the experimental apparatus using the electric motor 10.

  The experimental result shown in FIG. 4 is a result of measuring the temperature of the magnet 33 when the electric motor 10 is actually driven using the electric motor 10 configured as shown in FIG.

  Specifically, the temperature of the electric motor 10 that has not been subjected to the high radiation surface treatment on the inner surface of the stator 20, the inner surface of the housing 41, and the inner surface of the bracket 42, and the temperature of the magnet 33 of each of the electric motors 10 that have undergone the high radiation treatment. Compared.

  The table shown in FIG. 4 shows that when the electric motor 10 is driven, the temperature of the magnet 33 of the electric motor 10 subjected to the high radiation surface treatment with respect to the temperature of the magnet 33 of the electric motor 10 not subjected to the high radiation surface treatment. The degree of the reduction was expressed as a temperature reduction rate in percentage.

  Referring to the results shown in FIG. 4, it has been clarified that the temperature of the magnet 33 is reduced by about several percent by performing a high radiation surface treatment on the surface of the stator 20.

  Therefore, it was confirmed that the heat dissipation of the magnet 33 can be improved by the high radiation surface treatment.

  Next, the experimental results of heat dissipation by the film thickness of the high radiation surface treatment film will be described.

  FIG. 5 is an explanatory diagram showing the relationship between the film thickness of the high radiation coating used for the high radiation surface treatment and the radiation rate. Note that the emissivity was measured using infrared radiation with the infrared spectrophotometer (FT-IR) described above with reference to FIG.

  According to the experimental results shown in FIG. 5, it can be confirmed that the radiation rate is greatly reduced when the film thickness is approximately 10 [μm] or less. On the other hand, when the film is 10 [μm] or more, it can be confirmed that the radiation rate is substantially constant. Therefore, it was confirmed that the film thickness of the high radiation coating was desirably 10 [μm] or more.

  As described above, the electric motor 10 according to the first embodiment of the present invention includes the stator 20 accommodated in the housing 41 and the rotor 30 that is rotatably supported inside the stator 20. Then, a high radiation surface treatment in which a high radiation coating was formed on the interface with the internal air gap of the housing 41 and the interface with the internal air gap of the stator 20 was performed.

  By this high radiation surface treatment, the radiation transmission of the heat generated from the coil end 23 of the rotor 30 or the stator 20 is promoted, and the heat transmission to the housing 41 can be improved.

  Further, since the housing 41 includes the cooling liquid passage 41a inside the wall thickness, the heat transmitted to the housing 41 can be quickly discharged to the outside. With such a configuration, the electric motor 10 can be cooled without releasing the heat generated from the electric motor 10 to the periphery of the electric motor 10.

  For example, in a vehicle (EV, HEV) equipped with the electric motor 10 and using this as a drive source, the space around the electric motor is limited, so that other components and the electric motor are arranged close to each other. In such a vehicle, since the heat generated by the electric motor 10 is cooled by the coolant, the thermal influence on other components can be reduced.

  In addition, since the surface of the inner peripheral surface of the housing 41 facing the coil end 23 of the stator 20 is subjected to high radiation surface treatment, the heat of the coil end 23 that becomes high temperature can be efficiently transferred to the housing 41. Can communicate. Similarly, since the surface of the stator 20 facing the rotor 30 is subjected to high radiation treatment, the heat of the rotor 30 that is at a high temperature can be efficiently transmitted to the housing 41.

  Further, by limiting the portion to which the high radiation surface treatment is applied, heat can be efficiently transferred to the housing 41 with a small area of the high radiation surface treatment.

  The high radiation coating is a coating film in which one or more particles exhibiting high radiation characteristics such as metal oxide, carbon black, silicon carbide, etc. are dispersed in an epoxy resin or acrylic resin material, or an amide imide ester. It is composed of a system film. By using such a material, it is possible to obtain a film having a wide and stable high radiation characteristic with respect to the operating temperature and the wavelength of the radiated electromagnetic wave by a relatively simple method.

  The thickness of the high radiation coating is desirably 10 μm or more, so that a coating with stable radiation characteristics can be formed.

<Second Embodiment>
Next, a second embodiment will be described. FIG. 6 is a cross-sectional view of the electric motor 10 according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the description is abbreviate | omitted.

  In the second embodiment, the high radiation surface treatment in which the high radiation film is formed is applied not only to the interface with the internal air gap of the housing 41 and the interface with the internal air gap of the stator 20 but also to the surface of the rotor 30. A highly radiant surface treatment was applied.

  The formation of the highly radiant film is the same as the process described above in the first embodiment. That is, when the electric motor 10 is assembled, a highly radiant surface coating is formed on the surface of the rotor 30 and the surface of the end plate 34 of the rotor 30.

  The electric motor 10 of the second embodiment configured as described above has a high radiation surface in which a high radiation film is formed on the surface of the rotor 30 on the heat radiation side as well as the interface with the housing 41 and the internal gap of the stator 20. Treated.

  With such a configuration, the heat generated from the rotor 30 can be efficiently transmitted to the housing 41, and the heat can be quickly discharged to the outside. With such a configuration, the electric motor 10 can be cooled without releasing the heat generated from the electric motor 10 to the periphery of the electric motor 10.

<Third Embodiment>
Next, a third embodiment will be described. FIG. 7 is a cross-sectional view of the electric motor 10 according to the third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the description is abbreviate | omitted.

  In the third embodiment, the outer peripheral surface of the housing is made highly reflective in comparison with the first embodiment described above.

  Due to the heat generated in the electric motor 10, the temperature of the housing 41 rises. Although the coolant flows through the housing 41, since the heat resistance is present, the heat received by the housing 41 is not all transmitted immediately to the outside, and the surface temperature of the housing 41 may increase. There is a possibility that the components around the electric motor 10 are thermally affected by the temperature rise of the housing 41.

  On the other hand, when there is a part that generates high heat, such as an internal combustion engine, in the vicinity where the electric motor 10 is provided, the temperature of the electric motor 10 may rise due to the influence of this part.

  On the other hand, in the third embodiment, the heat radiation to the components around the electric motor 10 is performed at the location indicated by the dotted line in FIG. In addition, the heat receiving from the components around the electric motor 10 is reduced.

  Similarly, it is desirable that the surface of a part around the part where the electric motor 10 is arranged, particularly the part arranged close to the electric motor 10, has a high reflectance. The components arranged close to the electric motor 10 are, for example, an inverter case, a member that fixes the electric motor 10, and the like.

  The high reflection treatment is performed by making the surface a metal substrate or polishing the surface to give a mirror finish.

  In the electric motor 10 of the third embodiment configured as described above, the outer peripheral surface of the housing 41 is subjected to high reflection treatment. Thereby, it is possible to suppress the heat from being applied to the parts around the electric motor 10 from the electric motor 10, and it is possible to reduce the thermal influence on the peripheral parts.

  Furthermore, the heat generated by the components around the electric motor 10 is suppressed from being transmitted to the electric motor 10, and the electric motor 10 can reduce the influence of heat from the outside.

  In particular, in a vehicle (EV, HEV) on which the electric motor 10 is mounted, since the space around the electric motor is limited, other components and the electric motor must be arranged close to each other. Even in such a vehicle, the thermal influence on other components can be reduced.

DESCRIPTION OF SYMBOLS 10 Electric motor 20 Stator 21 Starter core 22 Coil 23 Coil end 30 Rotor 31 Rotating shaft 32 Rotor core 33 Magnet 34 End plate 41 Housing 41a Cooling liquid path 42 Bracket 43 Trunk part

Claims (9)

A stator wound with a coil;
A rotor provided on the inner peripheral side of the stator;
Housing the stator, rotatably supporting the rotor, and having a cooling liquid passage through which a cooling liquid flows, and a housing.
In the housing, a high radiation coating having high radiation characteristics is formed at an interface with the internal gap formed by the housing, and heat generated from the stator and the coil is transferred to the housing through the high radiation coating. An electric motor characterized by transmitting.   2. The electric motor according to claim 1, wherein the high radiation coating is formed on an interface at a position facing the rotor among the interface with the internal gap.   3. The electric motor according to claim 1, wherein the high radiation coating is formed on an interface of the housing at a position facing the coil in an interface with the internal gap. 4.   4. The electric motor according to claim 1, wherein the high radiation coating is formed on an interface of the housing at a position facing the rotor in an interface with the internal gap. 5. motor.   The electric motor according to claim 1, wherein the rotor has a high radiation coating formed on a surface thereof.   The high radiation characteristic film is a film comprising an epoxy resin or acrylic resin material in which at least one kind of particles having a high radiation characteristic composed of a metal oxide, carbon black, or silicon carbide is dispersed, or an amide imide The electric motor according to claim 1, wherein the electric motor is an ester film.   The electric motor according to claim 6, wherein the high radiation characteristic film has a film thickness of at least 10 μm.   The housing is characterized in that a surface with high reflectivity is formed at an interface with an external space, and a surface with high reflectivity is formed on the surface of an object installed in the vicinity of the housing. Item 8. The electric motor according to any one of Items 1 to 7. Winding a coil around the stator;
Fixing the coil end portion of the wound coil and filling the varnish;
Inserting the stator around which the coil is wound into a housing;
Forming a high radiation coating having high radiation characteristics on the interface of the housing and the interface of the stator;
Inserting a rotor on the inner peripheral side of the stator, and fixing the rotor to the housing in a rotatable manner;
The manufacturing method of the electric motor characterized by the above-mentioned.

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