JP2008289244A - Cooling structure of rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure of a rotary electric machine, which promotes heat dissipation of a stator. <P>SOLUTION: The cooling structure of a motor generator as a rotary electric machine includes a motor case 21, a stator 50 having a bolt inserting hole 57 formed thereon and housed in the motor case 21, and a bolt 56 inserted into the bolt inserting hole 57 to fasten the stator 50 to the motor case 21. The bolt 56 has a hollow portion 58 having a heat medium sealed thereinto, and works as a heat pipe. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention generally relates to a cooling structure for a rotating electrical machine, and more particularly to a cooling structure for a rotating electrical machine in which a stator is bolted to a case body.

  Regarding a conventional cooling structure for a rotating electrical machine, for example, Japanese Patent Application Laid-Open No. 2002-315235 discloses a motor for the purpose of facilitating assembly of a stator using a split iron core (Patent Document 1). . The motor disclosed in Patent Document 1 includes a stator that generates a rotating magnetic field by arranging a plurality of split iron cores wound with windings in an annular shape, and a housing that fixes the stator. The stator is attached to the housing from the other end surface side with a through bolt that fits one end surface side into the housing and penetrates the iron core.

Japanese Patent Laid-Open No. 2003-204656 discloses an automotive alternator aimed at maintaining stable cooling performance even in a long-time high temperature environment (Patent Document 2). In patent document 2, the control part which controls a generated voltage is being fixed to the rear bracket with the fastening member. The heat of the control unit is transmitted to the rear bracket via the fastening member.
JP 2002-315235 A JP 2003-204656 A

  In a rotating electrical machine such as a motor, heat generation of a coil and a stator core around which the coil is wound cannot be avoided. For this reason, it becomes a problem how efficiently this heat is radiated from the stator. However, the motors and automotive AC generators disclosed in the above-mentioned patent documents have room for improvement in terms of heat dissipation from the stator.

  Accordingly, an object of the present invention is to solve the above-described problem and to provide a rotating electrical machine cooling structure in which heat dissipation of the stator is promoted.

  A cooling structure for a rotating electrical machine according to the present invention includes a case body, a stator in which a through-hole is formed and accommodated in the case body, and a bolt that is inserted into the through-hole and fastens the stator to the case body. The bolt has a hollow portion in which a heat medium is enclosed, and functions as a heat pipe.

  According to the cooling structure for a rotating electric machine configured as described above, the heat generated in the stator is transmitted to the case body through the heat medium sealed in the hollow portion by causing the bolt to function as a heat pipe. Thereby, heat dissipation from the stator to the case body can be promoted.

  Preferably, the bolt includes a fastening portion fastened to the case body. The hollow portion extends in the penetration direction of the through hole and extends to the inside of the fastening portion. According to the rotating electrical machine cooling structure configured as described above, the heat of the heat medium can be efficiently transmitted to the case body.

  Preferably, the stator includes a plurality of electromagnetic steel plates stacked in the through direction of the through hole. According to the cooling structure for a rotating electric machine configured as described above, heat conduction in the stator is hindered in the stacking direction of the electromagnetic steel sheets due to a minute air layer or the like interposed between the plurality of electromagnetic steel sheets. On the other hand, the heat conduction in the stator in the lamination direction of the electromagnetic steel sheets can be promoted by causing the bolt to function as a heat pipe.

  Preferably, the case body includes a side portion disposed on the outer periphery of the stator and a bottom portion disposed at one end of the side portion in the axial direction of the stator. A gap is formed between the stator and the side portion. A stator is fastened to the bottom. According to the cooling structure for a rotating electric machine configured as described above, since a gap is formed between the stator and the side portion, it is difficult to efficiently dissipate heat from the stator to the case body. On the other hand, by causing the bolt to function as a heat pipe, heat dissipation from the stator to the bottom portion to which the stator is fastened can be promoted.

  As described above, according to the present invention, it is possible to provide a cooling structure for a rotating electrical machine in which heat dissipation of the stator is promoted.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

  FIG. 1 is a sectional view schematically showing a drive unit to which a motor generator cooling structure according to an embodiment of the present invention is applied. The drive unit shown in the figure is mounted on a hybrid vehicle that uses an internal combustion engine such as a gasoline engine or a diesel engine and a rechargeable secondary battery (battery) as a power source.

  Referring to FIG. 1, the drive unit includes a motor generator 11. The motor generator 11 is a rotating electrical machine having a function as an electric motor or a generator. Motor generator 11 includes a rotor 30, a stator 50, and a motor case 21. A stator 50 is disposed on the outer periphery of the rotor 30. The central axis 101 extends in the horizontal direction. The rotor 30 and the stator 50 are accommodated in the motor case 21. The stator 50 is fixed to the motor case 21.

  The rotor 30 has a shape extending in a cylindrical shape in the axial direction of the central axis 101 which is a virtual axis. Rotor 30 includes a plurality of electromagnetic steel plates 32. The plurality of electromagnetic steel plates 32 are stacked in the axial direction of the central axis 101. The rotor 30 is fixed to a shaft 43 that extends in the axial direction of the central shaft 101. The shaft 43 is rotatably supported with respect to the motor case 21 via a bearing (not shown). A hole 24 is formed in the motor case 21. A shaft 43 is inserted into the hole 24. The shaft 43 is connected to a speed reduction mechanism 14 that includes a plurality of gears. A permanent magnet 31 is embedded in the rotor 30. The rotor 30 rotates around the central axis 101 together with the shaft 43.

  The rotor 30 is an IPM (Interior Permanent Magnet) rotor. The rotor 30 is not limited to this, and may be an SPM (surface permanent magnet) rotor in which a magnet is attached to the rotor surface.

  The stator 50 has a shape extending in a cylindrical shape in the axial direction of the central shaft 101. Stator 50 includes a plurality of electromagnetic steel plates 52. The plurality of electromagnetic steel plates 52 are stacked in the axial direction of the central axis 101. The electromagnetic steel plate 52 has a thin plate shape. The electromagnetic steel plate 52 has a thin plate shape so that when one edge is gripped, the other edge hangs vertically downward. The electromagnetic steel sheet 52 has a thickness of 1 mm or less, for example. The plurality of laminated electromagnetic steel sheets 52 are coupled to each other by means such as welding or caulking.

  The stator 50 includes an end surface 50a at one end in the direction in which the central shaft 101 extends, and an end surface 50b at the other end. The end surface 50 a and the end surface 50 b extend in a plane orthogonal to the central axis 101.

  A coil 51 is wound around the stator 50. The coil 51 is formed of, for example, a copper wire with an insulating coating. Coil 51 includes a U-phase, V-phase, and W-phase coil. Terminals corresponding to these phase coils are connected to the terminal block 17. The terminal block 17 is electrically connected to the battery 19 via the inverter 18. The inverter 18 converts the direct current from the battery 19 into an alternating current for driving the motor, and converts the alternating current generated by the regenerative brake into a direct current for charging the battery 19.

  The power output from the motor generator 11 is transmitted from the speed reduction mechanism 14 to the drive shaft receiving portion 16 via the differential mechanism 15. The power transmitted to the drive shaft receiving portion 16 is transmitted as a rotational force to a wheel (not shown) via the drive shaft.

  On the other hand, during regenerative braking of the hybrid vehicle, the wheels are rotated by the inertial force of the vehicle body. The motor generator 11 is driven via the drive shaft receiving portion 16, the differential mechanism 15, and the speed reduction mechanism 14 by the rotational force from the wheels. At this time, the motor generator 11 operates as a generator. The electric power generated by the motor generator 11 is stored in the battery 19 via the inverter 18.

  FIG. 2 is an end view of the motor generator along the line II-II in FIG. In the drawing, the winding structure of the motor generator 11 is schematically shown.

  Referring to FIGS. 1 and 2, stator 50 includes flange portions 54A, 54B and 54C (hereinafter referred to as flange portion 54 unless otherwise distinguished). The flange 54 is formed integrally with the electromagnetic steel plate 52. A plurality of flanges 54 are formed at intervals in the circumferential direction around the central axis 101. The flange portion 54A, the flange portion 54B, and the flange portion 54C are arranged at equal intervals. The flange 54 protrudes outward in the radial direction from the peripheral edge of the stator 50 with the central axis 101 as the center.

  Bolt insertion holes 57 are formed in the stator 50 so as to penetrate in the laminating direction of the electromagnetic steel plates 52. The bolt insertion hole 57 is formed in the flange portion 54 of each electromagnetic steel plate 52. The bolt insertion hole 57 passes through the stator 50. The bolt insertion holes 57 extend in the axial direction of the central shaft 101 and open to the end surface 50a and the end surface 50b, respectively. The number of bolt insertion holes 57 formed is not limited to three, and can be changed as appropriate.

  The stator 50 is arranged in a ring shape around the central shaft 101 and a yoke portion 50y that is arranged at a predetermined interval in the circumferential direction of the yoke portion 50y, and a plurality of stators 50 project radially inward from the inner peripheral surface of the yoke portion 50y. Teeth portion 50t. A slot portion 50s is formed in a space surrounded by the adjacent tooth portions 50t and the yoke portion 50y. The slot portion 50 s opens at a position facing the rotor 30.

  Coil 51 includes a U-phase coil 51U, a V-phase coil 51V, and a W-phase coil 51W. The coil 51 is wound around the stator 50 by so-called distributed winding.

  Explaining the form, the U-phase coil 51U, the V-phase coil 51V, and the W-phase coil 51W are respectively provided at a plurality of locations so as to circulate around a plurality of teeth portions 50t continuously arranged in the circumferential direction. Yes. The U-phase coil 51U, the V-phase coil 51V, and the W-phase coil 51W are wound so as to pass over the slot portions 50s on both sides of the plurality of tooth portions 50t and the end surfaces 50a and 50b. The U-phase coil 51U, the V-phase coil 51V, and the W-phase coil 51W are wound side by side from the outer peripheral side to the inner peripheral side in the order listed. The U-phase coil 51U, the V-phase coil 51V, and the W-phase coil 51W are wound around the tooth portion 50t at positions shifted from each other in the circumferential direction.

  Note that the coil 51 is not limited to distributed winding, and the coil 51 may be wound around the stator 50 by so-called concentrated winding in which the coil 51 is intensively wound around the tooth portion 50t for each magnetic pole.

  3 is a cross-sectional view showing a range surrounded by a two-dot chain line III in FIG. Referring to FIGS. 1 and 3, motor case 21 is made of metal. A water jacket through which the refrigerant flows may be formed in the motor case 21.

  The motor case 21 includes a side portion 21m and a bottom portion 21n. The side portion 21m has a shape extending in a cylindrical shape in the axial direction of the central shaft 101. The side portion 21m is formed so as to surround the outer periphery of the stator 50. The bottom 21n is disposed at one end of the side 21m in the axial direction of the central axis 101. The hole 24 is formed in the bottom 21n. The stator 50 is placed on the bottom 21n. The bottom 21n and the end surface 50b of the stator 50 are in surface contact.

  A female screw 26 is formed in the motor case 21. The female screw 26 is formed on the bottom 21n. Motor generator 11 includes a bolt 56. The bolt 56 is inserted into the bolt insertion hole 57 and is screwed into the female screw 26. The stator 50 is fastened to the motor case 21 by bolts 56. The bolt 56 generates a fastening force in the stacking direction of the electromagnetic steel plates 52 and couples the stator 50 to the motor case 21. The bolt 56 is made of metal.

  The bolt 56 includes a head portion 56j and a shaft portion 56k. The head 56j is positioned on the end surface 50a of the stator 50. The shaft portion 56k is inserted into the bolt insertion hole 57 and screwed into the female screw portion 26. The bolt 56 includes a fastening portion 56p fastened to the motor case 21. The fastening portion 56p is a portion that is screwed into the female screw 26 in the shaft portion 56k.

  With reference to FIG. 3, the cross-sectional shape of the bolt 56 is shown. The bolt 56 includes a hollow portion 58. The hollow portion 58 is formed by a space inside the bolt 56. The hollow portion 58 is formed in the shaft portion 56k. The hollow portion 58 may be formed so as to be continuous between the head portion 56j and the shaft portion 56k. The hollow portion 58 extends in the axial direction of the shaft portion 56k, that is, along the penetration direction of the bolt insertion hole 57. The hollow portion 58 extends continuously between one end and the other end of the plurality of laminated electromagnetic steel plates 52. The hollow portion 58 extends to the inside of the fastening portion 56p.

  4 is a cross-sectional view of the bolt along the line IV-IV in FIG. 3 and 4, the bolt 56 includes an inner wall 59 formed with a groove shape as a capillary structure. A hollow portion 58 is formed at a position surrounded by the inner wall 59. The hollow portion 58 is sealed in a vacuum state. A small amount of heat medium (not shown) such as water, freon, or ammonia is sealed in the hollow portion 58. With such a configuration, the bolt 56 functions as a heat pipe.

  In FIG. 3 and FIG. 4, one hollow portion 58 is formed in the bolt 56. However, the present invention is not limited to this. Good. The capillary structure formed on the inner wall 59 and the heat medium sealed in the hollow portion 58 are appropriately changed.

  Referring to FIGS. 1 and 3, when motor generator 11 is driven, the temperature of stator 50 rises due to heat generation of electromagnetic steel sheet 52 and heat generation of coil 51. In the present embodiment, the heat of the stator 50 is absorbed by the heat medium enclosed in the hollow portion 58. Thereby, the heat medium evaporates and moves from the inside of the stator 50 toward the inside of the motor case 21. The heat medium that has reached the inside of the motor case 21 releases heat by exchanging heat with the motor case 21. The heat medium returns to the liquid and moves toward the inside of the stator 50 by the capillary action due to the groove shape formed in the inner wall 59. The heat medium returned to the inside of the stator 50 absorbs the heat of the stator 50 again. By repeating such a cycle, the heat of the stator 50 is radiated to the motor case 21.

  FIG. 5 is a diagram for explaining heat conduction in the stator in FIG. 1. Referring to FIG. 5, the present embodiment includes a plurality of electromagnetic steel plates 52 on which stator 50 is laminated. In this case, a minute air layer is formed between the plurality of electromagnetic steel plates 52 regardless of the fastening force by the bolts 56. For this reason, the thermal conductivity in the stator 50 is compared with the extending direction of each electromagnetic steel sheet 52 (radial direction centering on the central axis 101), and in the stacking direction of the plurality of electromagnetic steel sheets 52 (axis of the central axis 101). Direction). On the other hand, in this Embodiment, the heat conduction in the lamination direction of the some electromagnetic steel plate 52 can be promoted by providing the volt | bolt 56 which functions as a heat pipe.

  FIG. 6 is a cross-sectional view of the motor generator along the line VI-VI in FIG. In the drawing, the outer shape of the stator 50 is represented by a two-dot chain line. Referring to FIG. 6, a gap 80 is formed between side portion 21 m of motor case 21 and stator 50. The side portion 21m is not in contact with the stator 50. In this case, heat radiation from the stator 50 to the motor case 21 is limited to a path through the bottom 21n. For this reason, heat cannot be efficiently transmitted from the stator 50 to the motor case 21, and the temperature rise of the stator 50 tends to be a problem. On the other hand, in the present embodiment, by providing the bolt 56 functioning as a heat pipe, the heat radiation from the stator 50 to the motor case 21 can be efficiently performed.

  A resin sleeve may be inserted between the inner wall of the bolt insertion hole 57 and the bolt 56. Thereby, the heat of the stator 50 can be efficiently absorbed by the heat medium of the hollow portion 58. In addition, when the nominal thread of the bolt 56 (specified in JIS B 0205) is M (k), the length of the fastening portion 56p is preferably 2k or more. The length of the fastening portion 56p is more preferably 3k or more. In these cases, the heat of the heat medium can be efficiently transmitted to the motor case 21 by sufficiently securing the fastening length between the bolt 56 and the motor case 21.

  The motor generator 11 cooling structure according to the embodiment of the present invention includes a motor case 21 as a case body, a bolt insertion hole 57 as a through hole, a stator 50 accommodated in the motor case 21, and a bolt insertion hole. And a bolt 56 that is inserted into the motor case 21 and fastens the stator 50 to the motor case 21. The bolt 56 has a hollow portion 58 in which a heat medium is enclosed, and functions as a heat pipe.

  According to the cooling structure of motor generator 11 in the embodiment of the present invention configured as described above, the heat dissipation from stator 50 to motor case 21 can be promoted by providing bolt 56 that functions as a heat pipe. it can. In addition, since it is not necessary to provide a new part for cooling the stator 50, the above-described effects can be achieved with a simple configuration.

  In the present embodiment, the case where the rotor 30 and the stator 50 are respectively formed from the electromagnetic steel plates 32 and 52 has been described. However, the rotor 30 and the stator 50 are not limited to the electromagnetic steel plates, and are formed from other magnetic materials such as a dust core. May be. The rotating electrical machine cooling structure according to the present invention may be applied to a motor mounted on an electric vehicle or a general industrial motor. The cooling structure for a rotating electrical machine in the present invention may be applied to a motor that is disposed on a vehicle wheel and drives the wheel, a so-called in-wheel motor.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is sectional drawing which represents typically the drive unit to which the cooling structure of the motor generator in embodiment of this invention was applied. FIG. 2 is an end view of the motor generator along the line II-II in FIG. 1. It is sectional drawing which shows the range enclosed by the dashed-two dotted line III in FIG. It is sectional drawing of the volt | bolt along the IV-IV line | wire in FIG. It is a figure for demonstrating the heat conduction in the stator in FIG. It is sectional drawing of the motor generator along the VI-VI line in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Motor generator, 21 Motor case, 21m side part, 21n bottom part, 50 stator, 52 Magnetic steel sheet, 56 bolt, 56p Fastening part, 57 Bolt insertion hole, 58 Hollow part.

Claims (4)

The case body,
A stator in which a through hole is formed and accommodated in the case body;
A bolt inserted into the through hole and fastening the stator to the case body;
The bolt has a hollow portion in which a heat medium is sealed, and functions as a heat pipe. The bolt includes a fastening portion fastened to the case body,
The cooling structure for a rotating electrical machine according to claim 1, wherein the hollow portion extends in a penetrating direction of the through hole and extends to the inside of the fastening portion.   The cooling structure for a rotating electrical machine according to claim 1, wherein the stator includes a plurality of electromagnetic steel plates stacked in a through direction of the through hole. The case body includes a side portion disposed on the outer periphery of the stator and a bottom portion disposed at one end of the side portion in the axial direction of the stator,
A gap is formed between the stator and the side part,
The cooling structure for a rotating electric machine according to any one of claims 1 to 3, wherein the stator is fastened to the bottom portion.

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