JP2009268327A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor capable of suppressing temperature rise of a coil and achieving miniaturization thereof in a simple configuration. <P>SOLUTION: A plurality of grooves 24 extending in the axial direction and a plurality of fins 25 protruded in the radial direction are formed on the outer peripheral surface of a housing 21. The evaporator 31 of a U-shaped heat pipe 30 is inserted into a slot 13, and a condenser 32 is inserted into the groove 24. The slot 13 is filled with grease 40 of a high thermal conductivity. The heat generated at the coil 14 is transferred to a housing 21 through the grease 40 and the heat pipe 30, and also the heat generated at the coil 14 is transferred to the housing 21 through an insulator 17 formed of resin of the high thermal conductivity and a stator core 10. The outer peripheral surface of the housing 21 is cooled down by an air flow generated in accordance with the rotation of an impellor 19. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brushless motor having a function of suppressing a temperature rise of a coil.

  The stator of a brushless motor includes a core back portion and a plurality of teeth protruding in the radial direction from the core back portion. A plurality of coils are formed by winding a conductive wire around each of the plurality of teeth. The brushless motor rotates the rotor by supplying a drive current to a plurality of coils.

  When the drive current flows, the coil generates heat due to the electrical resistance of the coil, and the temperature rises. The temperature rise of the coil is accompanied by an increase in the electrical resistance of the coil, which causes the rotational performance of the brushless motor to deteriorate. Therefore, in order to prevent the temperature of the coil from increasing, the coil is conventionally cooled.

  For example, Patent Document 1 discloses a cooling structure for a motor mounted on an electric vehicle or the like. In the cooling structure of the motor disclosed in Patent Document 1, a refrigerant pipe is passed through a slot portion formed between adjacent teeth portions, and the refrigerant is sprayed toward a winding from a hole formed in the refrigerant pipe. .

JP 2005-168265 A

  As described above, Patent Document 1 discloses a cooling structure for a motor that directly cools a winding with a refrigerant sprayed from a refrigerant pipe.

  However, the motor cooling structure disclosed in Patent Document 1 requires a configuration for collecting the refrigerant sprayed from the refrigerant pipe and the refrigerant that has not been sprayed. For this reason, the motor cooling structure disclosed in Patent Document 1 has a problem that the structure becomes complicated. The motor cooling structure disclosed in Patent Document 1 is premised on being mounted on an electric vehicle or the like. That is, a heat exchanger is used for cooling the recovered refrigerant, and there is a problem that it is difficult to reduce the size of the motor.

  In view of the above problems, an object of the present invention is to provide a brushless motor that can reduce the temperature of the coil with a simple configuration and can be downsized.

  In order to solve the above-mentioned problems, a first aspect of the present invention includes a rotor that rotates about a rotation shaft, and a plurality of teeth that extend in a radial direction from an inner peripheral surface of an annular core back portion centered on the rotation shaft. A stator core, a plurality of coils formed by winding conductive wires around each tooth, a cylindrical shape, a housing whose inner peripheral surface is in contact with the outer peripheral surface of the stator core, and a tooth whose one end is adjacent A plurality of heat pipes inserted into a slot formed between the other ends and contacting the housing.

  According to a second aspect of the present invention, in the brushless motor according to the first aspect, each heat pipe has a U-shape.

  According to a third aspect of the present invention, in the brushless motor according to the second aspect, a plurality of grooves extending along the axial direction are formed on the outer peripheral surface of the housing, and the other end side of each heat pipe is It is characterized by being inserted into each groove.

  According to a fourth aspect of the present invention, in the brushless motor according to any one of the first to third aspects, the gap formed between each coil and each heat pipe has electrical insulation and heat conduction of air. It is characterized by being filled with a filler having a thermal conductivity greater than that.

  According to a fifth aspect of the present invention, in the brushless motor according to any one of the first to fourth aspects, an insulating layer having electrical insulation is formed on the surface of each heat pipe.

  The invention according to claim 6 is the brushless motor according to claim 5, wherein the insulating layer is formed on one end side of each heat pipe and electrically insulates each heat pipe from each coil. To do.

  A seventh aspect of the present invention is the brushless motor according to any one of the first to sixth aspects, further comprising a resin having electrical insulation and a thermal conductivity of 2.0 W / m · K or more. And an insulator that covers the stator core.

  According to an eighth aspect of the present invention, in the brushless motor according to the seventh aspect, a gap formed between the conductive wires forming each coil, and a gap formed between the conductive wires and the insulator. Is filled with a filler having electrical insulation and a thermal conductivity greater than that of air.

  The invention according to claim 9 is a rotor that rotates about a rotating shaft, a stator core having a plurality of teeth extending radially from an inner peripheral surface of an annular core back portion centered on the rotating shaft, and electrical insulation And an insulator covering the stator core, and a plurality of conductor wires wound around each of the teeth covered by the insulator. And a housing having an inner peripheral surface in contact with the outer peripheral surface of the stator core.

  A tenth aspect of the present invention is the brushless motor according to the ninth aspect, wherein a gap is formed between the conductive wires forming each coil, and a gap is formed between the conductive wires and the insulator. Is filled with a filler having electrical insulation and a thermal conductivity greater than that of air.

  The invention described in claim 11 is the brushless motor according to claim 9 or claim 10, further comprising a plurality of heat pipes having a U-shape, and the outer peripheral surface of the housing is provided in an axial direction. A plurality of grooves extending along the groove are formed, one end of each heat pipe is inserted into a slot formed between adjacent teeth, and the other end of each heat pipe is inserted into each groove.

  According to a twelfth aspect of the present invention, in the brushless motor according to the eleventh aspect, the gap formed between each coil and each heat pipe is electrically insulating and has a heat larger than the thermal conductivity of air. It is characterized by being filled with a filler having conductivity.

  A thirteenth aspect of the present invention is the brushless motor according to any one of the first to twelfth aspects, wherein the housing has a plurality of radiating fins protruding outward in the radial direction from an outer peripheral surface. .

  A fourteenth aspect of the present invention is the brushless motor according to the thirteenth aspect, wherein each of the heat dissipating fins is curved in one circumferential direction.

  According to a fifteenth aspect of the present invention, in the brushless motor according to any one of the first to fourteenth aspects, the brushless motor is further disposed on one end side of the stator core with respect to the axial direction, and generates an air flow for cooling the housing. A cooling unit.

  A sixteenth aspect of the present invention is the brushless motor according to the fifteenth aspect, wherein the cooling unit includes an impeller that generates the airflow by rotating integrally with the rotor.

  According to a seventeenth aspect of the present invention, in the brushless motor according to the fifteenth aspect, the cooling unit includes an impeller that generates the air flow by rotating the cooling unit, and a driving unit that rotates the impeller. It is characterized by having.

  The invention according to claim 18 is the brushless motor according to any one of claims 1 to 17, wherein the brushless motor is used in a brush cutter.

  In the brushless motor according to the present invention, one end side of the plurality of heat pipes is inserted into each slot, and the other end side is in contact with the housing. The heat generated in the coil moves to the housing via the heat pipe and is released from the housing to the outside of the brushless motor. Thus, the brushless motor according to the present invention can prevent the temperature of the coil from rising with a simple configuration, and can reduce the size of the brushless motor.

  In addition, since the gap formed between the heat pipe and the coil is filled with a filler having an electrical insulation property and a thermal conductivity larger than the thermal conductivity of air, the heat pipe efficiently absorbs the heat generated in the coil. Can tell.

  Further, since the insulator is formed of a resin having an electrical insulation property and a thermal conductivity of 2.0 W / m · K or more, the heat generated by the coil can be transferred to the housing via the insulator and the stator core. . Thus, the brushless motor according to the present invention can prevent the temperature of the coil from rising with a simple configuration, and can reduce the size of the brushless motor.

{Overall configuration of brushless motor 1}
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view of a brushless motor 1 according to the present embodiment. FIG. 2 is a plan sectional view of the brushless motor 1. The side cross-sectional view shown in FIG. 1 corresponds to the cross section taken along the line BB shown in FIG. 2, and the plan cross-sectional view shown in FIG. 2 corresponds to the cross section taken along the line AA shown in FIG.

  The brushless motor 1 shown in FIG. 1 is mounted on a brush cutter, for example. The brushless motor 1 is not limited to the brush cutter, and may be mounted on other devices such as a chain saw or a lawn mower.

  The brushless motor 1 is mounted in various directions depending on the mounted device. Therefore, the brushless motor 1 has no absolute vertical direction. However, in the following description, for convenience, it is assumed that the vertical direction on the drawing of FIG. 1 is the vertical direction of the brushless motor 1.

  The housing 21 has a cylindrical shape with the rotation axis J1 of the brushless motor 1 as the center, and the stator core 10 is fixed to the inner peripheral surface. The stator core 10 is a metallic member formed by laminating silicon steel plates and the like. The stator core 10 includes a core back portion 11 that is formed in an annular shape around the rotation axis J1, and a plurality of teeth portions 12 that are arranged radially from the core back portion 11 toward the rotation axis J1. A plurality of coils 14 are formed by winding the conductive wire 140 around each tooth portion 12 covered with the insulator 17.

  Further, the evaporation part 31 of the heat pipe 30 is inserted into the slot 13 formed between the adjacent tooth parts 12, and the condensing part 32 is inserted into the groove 24 formed in the housing 21. The heat pipe 30 conducts heat generated in the coil 14 to the housing 21. In FIGS. 1 and 2, the display of the internal structure of the heat pipe 30 is omitted.

  Brackets 22 and 23 are disposed on the upper side and the lower side of the housing 21, respectively. The brackets 22 and 23 are fixed to the housing 21 by screws or the like. The brackets 22 and 23 hold ball bearings 18 and 18, respectively. A shaft 15 having the rotation axis J1 as an axis is rotatably held by ball bearings 18 and 18 held by the brackets 22 and 23.

  The rotor 16 includes a rotor magnet 161 and a rotor core 162 and rotates integrally with the shaft 15. The rotor magnet 161 is fixed to the outer peripheral surface of the rotor core 162 fixed to the shaft 15.

  In the brushless motor 1 having the above-described configuration, a current corresponding to the rotational position of the rotor magnet 161 is supplied from the power supply device via the control device. As the drive current is supplied to the coil 14, a magnetic field is generated, and the rotor magnet 161 rotates. In this way, the brushless motor 1 obtains a rotational driving force.

{Heat dissipation structure of brushless motor 1}
Hereinafter, a heat dissipation structure of the brushless motor 1 for releasing heat generated in the coil 14 to the outside will be described. First, the outline of the heat flow in the brushless motor 1 will be described.

  In the brushless motor 1, the heat generated in the coil 14 by supplying the drive current is transmitted to the housing 21. A heat transfer path from the coil 14 to the housing 21 will be described later. Further, the impeller 19 rotates together with the rotor 16 with the supply of the drive current to the coil 14. The rotation of the impeller 19 generates an air flow from the upper side to the lower side. The air flow flows along the outer peripheral surface of the housing 21 to cool the housing 21.

  There are two heat transfer paths from the coil 14 to the housing 21. The first heat transfer path is a path through which heat is transferred in the order of the coil 14, the grease 40, the heat pipe 30, and the housing 21. The second heat transfer path is a path through which heat is transferred in the order of the coil 14, the insulator 17, the stator core 10, and the housing 21. Hereinafter, each heat transfer path will be described in detail.

{First heat transfer path}
First, the heat pipe 30 constituting the first heat transfer path will be described. As shown in FIG. 1, the heat pipe 30 is a metallic pipe having a U-shape. The inside of the heat pipe 30 is in a vacuum, and liquid such as pure water or alternative chlorofluorocarbon is enclosed.

  Let the end part of the heat pipe 30 be the evaporation part 31 and the condensation part 32. The evaporator 31 is inserted into the slot 13 formed in the stator core 10 from below, and the condenser 32 is inserted into the groove 24 formed in the housing 21 from below. The heat pipes 30 are arranged corresponding to the number of slots 13. Further, the curved portion 33 of the heat pipe 30 is located below the brushless motor 1. An insulating layer is formed on the surface of the heat pipe 30 from the curved portion 33 to the evaporation portion 31 by winding an insulating tape having electrical insulating properties. An insulating tape may be wound around the condensing unit 32.

  Next, the housing 21 will be described. The housing 21 functions as a heat sink that releases heat generated by the coil 14 to the outside of the brushless motor 1. As shown in FIG. 2, the housing 21 is a cylindrical metallic member centered on the rotation axis J1. A plurality of grooves 24 extending in the axial direction and heat radiation fins 25 are formed on the outer peripheral surface of the housing 21.

  The groove 24 is formed on the radially outer side of each slot 13. As described above, the condensing part 32 of the heat pipe 30 is inserted into the groove 24 from below. At this time, the wall surface of the groove 24 and the surface of the heat pipe 30 are in contact. By forming the groove 24 according to the cross-sectional shape of the heat pipe 30, the contact area between the wall surface of the groove 24 and the surface of the heat pipe 30 can be increased. Thereby, the heat released from the condensing part 32 of the heat pipe 30 can be efficiently transmitted to the housing 21.

  As shown in FIG. 2, the fin 25 protrudes radially outward from the outer peripheral surface of the housing 21 and is curved in one of the circumferential directions. By bending the fins 25, the surface area of the housing 21 can be increased. Therefore, the heat moved from the coil 14 to the housing 21 can be efficiently released to the outside of the brushless motor 1.

  Next, the impeller 19 will be described. As shown in FIG. 1, the impeller 19 has a configuration in which a plurality of blades 191 are provided on the outer periphery of a cup portion that opens downward. The impeller 19 is disposed on the upper side of the brushless motor 1 and is fixed to the shaft 15. That is, the impeller 19 and the curved portion 33 of the heat pipe 30 are located on the opposite sides with the bracket 22 interposed therebetween. The impeller 19 rotates integrally with the shaft 15 to generate an air flow that flows downward.

  Next, the grease 40 will be described. FIG. 3 is an enlarged view of a region C shown in FIG. That is, FIG. 3 is a diagram illustrating a state of the slot 13 in which the evaporation unit 31 of the heat pipe 30 is inserted. In FIG. 3, the display of the internal structure of the heat pipe 30 is omitted.

  As shown in FIG. 3, the slot 13 is filled with grease 40. The grease 40 is a paste-like member having an electrical insulating property and a thermal conductivity higher than that of air. However, the thermal conductivity of the grease 40 is desirably 0.8 (W / m · K) or more. For example, silicon resin or the like can be used as the grease 40. The slot 13 is in a state where the inner side in the radial direction is closed by the insulators 17 and 17. As a result, the grease 40 is prevented from leaking from the slot 13 to the radially inner side of the stator core 10.

  The evaporation part 31 of the heat pipe 30 inserted into the slot 13 is located at the center of the slot 13. The coils 14 and 14 are located on both sides in the circumferential direction of the evaporation portion 31 of the heat pipe 30 via the grease 40. For this reason, compared with a state where there is nothing between the coil 14 and the evaporation part 31 of the heat pipe 30, the heat generated in the coil 14 easily moves to the evaporation part 31 of the heat pipe 30 via the grease 40. can do.

  In addition, since the insulating tape is wound around the surface of the evaporation part 31 of the heat pipe 30, even if the coil 14 and the evaporation part 31 of the heat pipe 30 are in contact, the electricity between the coil 14 and the heat pipe 30 is Insulation can be secured. The insulating tape desirably has a thermal conductivity comparable to that of the grease 40 so that the heat generated in the coil 14 does not hinder the movement of the insulating tape to the heat pipe 30.

  FIG. 4 is an enlarged view of a region D shown in FIG. In FIG. 4, the cross-sectional shape of the conductive wire 140 forming the coil 14 is circular. As shown in FIG. 4, the gap 41 formed between the plurality of adjacent conductive lines 140 and the gap 42 formed between the plurality of adjacent conductive lines 140 and the insulator 17 are filled with the grease 40. Has been.

  The heat generated in the coil 14 is actually generated in the conductive wire 140 forming the coil 14. Since the conductive wire 140 is laminated in the coil 14, the heat generated in the conductive wire 140 located inside the coil 14 moves to the outside of the coil 14 through the adjacent conductive wire 140. However, when the grease 40 is filled in the gaps 41 and 42, the heat generated in the conductive wire 140 located inside the coil 14 not only moves through the adjacent conductive wire 140 but also passes through the grease 40. It becomes possible to move to the conductive line 140. This prevents heat generated in the coil 14 from being accumulated inside the coil 14.

  In addition, it is desirable that the grease 40 not only fills the slot 13 but also covers both sides of the tooth portion 12 in the axial direction. Thereby, since the coil 14 whole is covered with the grease 40, the heat which generate | occur | produces in the coil 14 whole can be efficiently transmitted to the evaporation part 31 of the heat pipe 30. FIG. Further, it is desirable that the evaporation part 31 of the heat pipe 30 protrudes above the stator core 10 in order to transmit heat generated in the upper part of the coil 14 to the housing 21.

  Next, heat transfer in the first heat transfer path will be described in detail. First, when a drive current is supplied to the coil 14, heat is generated in the conductive wire 140 that forms the coil 14. The heat generated in the conductive wire 140 moves to the outside of the coil 14 through the adjacent conductive wire 140 or the grease 40 that fills the gaps 41 and 42. The heat moved to the outside of the coil 14 moves to the evaporation part 31 of the heat pipe 30 through the grease 40 filling the slot 13.

  In the evaporation part 31 of the heat pipe 30, the liquid is evaporated by the heat transferred from the grease 40, and the vapor moves to the condensing part 32 having a lower temperature than the evaporation part 31. In the condensing unit 32, the vapor condenses, and the heat of condensation generated when the vapor condenses is transmitted to the housing 21. The heat transmitted to the housing 21 is released from the fins 25 by the air flow generated by the rotation of the impeller 19. As described above, by using the heat pipe 30, the heat generated in the coil 14 can be released to the outside of the brushless motor 1 without providing a configuration for collecting the refrigerant. Therefore, the brushless motor 1 can be downsized. it can.

{Second heat transfer path}
Next, the second heat transfer path will be described. Since the impeller 19 and the housing 21 are the same as described above, the description thereof is omitted. As described above, in the second heat transfer path, the heat generated in the coil 14 is transmitted to the housing 21 via the insulator 17 and the stator core 10.

  First, the insulator 17 will be described. FIG. 5A is a top view of the insulator 17. FIG. 5B is a bottom view of the insulator 17. FIG.5 (c) is a side view of the insulator 17 seen from the arrow E direction shown to Fig.5 (a). As shown in FIGS. 5A to 5C, the insulator 17 is formed in accordance with the shape of the tooth portion 12 and is attached to the stator core 10 so as to sandwich each tooth portion 12 from both sides in the axial direction. . The insulator 17 is formed of a resin (for example, an LCP resin) having an electrical insulating property and a thermal conductivity of 2.0 (W / m · K). However, the thermal conductivity of the insulator 17 is desirably 18 (W / m · K) or more. As shown in FIG. 4, the gaps 41 and 42 are filled with the grease 40. For this reason, the heat generated inside the coil 14 can move to the insulator 17.

  Further, as shown in FIG. 2, the outer peripheral surface of the stator core 10 and the inner peripheral surface of the housing 21 are in contact with each other. As a result, heat can be transferred from the stator core 10 to the housing 21. The contact between the outer peripheral surface of the stator core 10 and the inner peripheral surface of the housing 21 is not limited to the state in which the stator core 10 and the housing 21 are in direct contact, but between the outer peripheral surface of the stator core 10 and the inner peripheral surface of the housing 21. In addition, a state in which a thin film having a thermal conductivity similar to that of the grease 40 is interposed is included. That is, the movement of heat from the stator core 10 to the housing 21 may be prevented.

  Next, heat transfer in the second heat transfer path will be described in detail. When a drive current is supplied to the coil 14, heat is generated in the conductive wire 140 that forms the coil 14. The heat generated in the conductive wire 140 moves to the insulator 17 via the adjacent conductive wire 140 or the grease 40 that fills the gaps 41 and 42. The heat that has moved to the insulator 17 is transmitted to the housing 21 via the stator core 10. Since the stator core 10 is formed of a silicon steel plate or the like, the stator core 10 transmits heat transferred from the coil 14 to the insulator 17 to the housing 21. Similar to the first heat transfer path, the heat transferred to the housing 21 is released from the housing 21 to the outside of the brushless motor 1 by the air flow generated by the rotation of the impeller 19.

  Further, since the impeller 19 is disposed on the upper side of the brushless motor 1, the air flow generated by the rotation of the impeller 19 does not cool only the curved portion 33 of the heat pipe 30. That is, since the air flow cools the entire outer peripheral surface of the housing 21, the brushless motor 1 efficiently releases the heat that has moved to the housing 21 through the second heat transfer path from the housing 21 to the outside of the brushless motor 1. Can do.

  As described above, in the brushless motor 1 according to the present embodiment, the evaporation part 31 of the U-shaped heat pipe 30 is inserted into the slot 13 filled with the grease 40, and the condensation part 32 is formed in the housing 21. Each is inserted into the groove 24. Thereby, since the temperature rise of the coil 14 can be suppressed with a simple configuration, the brushless motor can be downsized.

  Further, by forming the insulator 17 with a resin having electrical insulation and high thermal conductivity, heat generated in the coil 14 can be transmitted to the housing 21 via the insulator 17 and the stator core 10. Thereby, since the heat which generate | occur | produces in the coil 14 moves to the housing 21 via two heat transfer paths, the temperature rise of the coil 14 can further be suppressed.

  In the present embodiment, the example in which the heat generated in the coil 14 is transmitted to the housing 21 by the first heat transfer path and the second heat transfer path has been described, but the present invention is not limited thereto. For example, the brushless motor 1 may have one of a first heat transfer path and a second heat transfer path.

  Moreover, in this Embodiment, although the example which the wall surface of the groove | channel 24 and the surface of the heat pipe 30 were contacting directly was demonstrated, it is not restricted to this. For example, a thin film such as an insulating tape having a thermal conductivity comparable to that of the grease 40 may be interposed between the wall surface of the groove 24 and the heat pipe 30.

  In the present embodiment, the case where the thermal conductivity of the grease 40 is larger than the thermal conductivity of air and the thermal conductivity of the insulator 17 is 2.0 (W / m · K) or more is described. However, in order to cool the coil 14 efficiently, it is desirable that the thermal conductivity of the grease 40 and the insulator 17 described in the present embodiment be as large as possible.

  In the present embodiment, the example in which the air flow is generated by the impeller 19 rotating integrally with the shaft 15 has been described, but the present invention is not limited thereto. For example, an air flow may be generated using an axial fan. The motor for driving the axial fan is a motor different from the brushless motor 1. In this case, the housing 21 can be cooled even when the brushless motor 1 is not driven.

  Moreover, in this Embodiment, although the thermal radiation structure corresponding to the three-phase brushless motor 1 was demonstrated, it is not restricted to this. The number of grooves 24 formed in the heat pipe 30 and the housing 21 may be changed according to the number of phases and the number of slots of the brushless motor.

It is side surface sectional drawing of the brushless motor which concerns on one embodiment of this invention. 1 is a plan sectional view of a brushless motor according to an embodiment of the present invention. FIG. 3 is an enlarged view of a region C shown in FIG. 2. FIG. 4 is an enlarged view of a region D shown in FIG. 3. It is a figure which shows the shape of an insulator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor 10 Stator core 11 Core back part 12 Teeth part 13 Slot 14 Coil 16 Rotor 17 Insulator 19 Impeller 21 Housing 24 Groove 25 Fin 30 Heat pipe 31 Evaporating part 32 Condensing part 33 Curved part 40 Grease 140 Conductive wire

Claims (18)

A rotor that rotates about a rotation axis;
A stator core having a plurality of teeth extending in a radial direction from an inner peripheral surface of an annular core back portion around the rotation axis;
A plurality of coils formed by winding a conductive wire around each tooth;
A housing having a cylindrical shape and an inner peripheral surface contacting the outer peripheral surface of the stator core;
A plurality of heat pipes having one end side inserted into a slot formed between adjacent teeth and the other end side contacting the housing;
A brushless motor comprising: The brushless motor according to claim 1,
Each heat pipe has a U-shape, and is a brushless motor. The brushless motor according to claim 2,
A plurality of grooves extending along the axial direction are formed on the outer peripheral surface of the housing,
A brushless motor, wherein the other end of each heat pipe is inserted into each groove. The brushless motor according to any one of claims 1 to 3,
A brushless motor characterized in that a gap formed between each coil and each heat pipe is filled with a filler having an electrical insulating property and a thermal conductivity larger than that of air. The brushless motor according to any one of claims 1 to 4,
A brushless motor, wherein an insulating layer having electrical insulation is formed on the surface of each heat pipe. The brushless motor according to claim 5,
The insulating layer is formed on one end side of each heat pipe, and electrically insulates each heat pipe and each coil. The brushless motor according to any one of claims 1 to 6, further comprising:
An insulator that is formed of a resin having an electrical insulating property and a thermal conductivity of 2.0 W / m · K or more, and covers the stator core;
A brushless motor comprising: The brushless motor according to claim 7,
The gap formed between the conductive wires forming each coil and the gap formed between the conductive wires and the insulator are electrically insulative and have a thermal conductivity greater than the thermal conductivity of air. A brushless motor characterized by being filled with a filler having A rotor that rotates about a rotation axis;
A stator core having a plurality of teeth extending in a radial direction from an inner peripheral surface of an annular core back portion around the rotation axis;
An insulator that is formed of a resin having electrical insulation properties and a thermal conductivity of 2.0 W / m · K or more, and covers the stator core;
A plurality of coils formed by winding a conductive wire around each of the teeth covered by the insulator;
A housing having a cylindrical shape and an inner peripheral surface in contact with an outer peripheral surface of the stator core;
A brushless motor comprising: The brushless motor according to claim 9,
The gap formed between the conductive wires forming each coil and the gap formed between the conductive wires and the insulator are electrically insulative and have a thermal conductivity greater than the thermal conductivity of air. A brushless motor characterized by being filled with a filler having The brushless motor according to claim 9 or 10, further comprising:
A plurality of U-shaped heat pipes,
With
A plurality of grooves extending along the axial direction are formed on the outer peripheral surface of the housing,
A brushless motor, wherein one end of each heat pipe is inserted into a slot formed between adjacent teeth, and the other end of each heat pipe is inserted into each groove. The brushless motor according to claim 11,
A brushless motor characterized in that a gap formed between each coil and each heat pipe is filled with a filler having an electrical insulating property and a thermal conductivity higher than that of air. . The brushless motor according to any one of claims 1 to 12,
The brushless motor, wherein the housing has a plurality of heat radiating fins protruding outward from the outer peripheral surface in the radial direction. The brushless motor according to claim 13,
Each of the heat dissipating fins is curved toward one direction in the circumferential direction. The brushless motor according to any one of claims 1 to 14, further comprising:
A cooling unit disposed on one end side of the stator core with respect to the axial direction and generating an air flow for cooling the housing;
A brushless motor comprising: The brushless motor according to claim 15,
The cooling part is
An impeller that generates the airflow by rotating integrally with the rotor;
A brushless motor characterized by comprising: The brushless motor according to claim 15,
The cooling part is
An impeller that generates the airflow by rotating;
A drive unit for rotating the impeller;
A brushless motor characterized by comprising: A brushless motor according to any one of claims 1 to 17,
A brushless motor, wherein the brushless motor is used in a brush cutter.

Images