JP2007110828A - Sealed motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed motor wherein an effect of cooling its rotor is enhanced. <P>SOLUTION: The sealed motor 1 is so constructed that a stator 3 is provided in a sealed casing 2 and a rotor 5 is rotatably provided in the stator 3 with an air gap 4 between. A thread-like spiral groove 7 for letting flow air in the sealed casing 2 is formed on the outer circumferential surface of the rotor 5. In addition, a through hole 8 for letting air flow in the sealed casing 2 in the axial direction is formed in the rotor 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hermetic motor in which a stator and a rotor are provided in a hermetic casing.

  Conventionally, for example, a motor having a permanent magnet on the rotor side, such as a DC brushless motor, is known. In such a motor, the rotor is air-cooled to prevent the permanent magnet of the rotor from becoming high temperature and reducing the magnetic force.

  For example, it has been proposed to cool the rotor by introducing fins into the motor by providing fins on the rotating shaft of the rotor and rotating the fins (see, for example, Patent Document 1).

  In addition, it has been proposed that a through hole extending in the axial direction is provided in the rotor and the rotor is cooled from the inside by air introduced from the outside of the motor (for example, see Patent Document 2).

JP-A-9-322480 JP-A-8-205438

  By the way, in order to improve the durability of the motor, there is a so-called sealed motor in which a stator and a rotor are accommodated in a sealed casing. In such a hermetic motor, heat tends to be trapped in the motor, and thus heat radiation of the rotor becomes a problem.

  However, since the motors described above have a structure in which outside air is taken into the motor and cooled, the cooling becomes insufficient even when the cooling structure is applied to a sealed motor. For example, when a structure in which fins are provided is applied, air flows only in one direction in the motor, and cooling is insufficient. Even when the through hole is provided, the rotor cannot be cooled only by introducing the heated air in the hermetic motor into the through hole.

  Thus, the conventional motor cooling structure has a problem that the hermetic motor cannot be sufficiently cooled. In particular, when trying to reduce the size and increase the capacity of a hermetic DC brushless motor, heat radiation from the permanent magnet of the rotor is an important issue.

  Accordingly, an object of the present invention is to provide a hermetic motor that can solve the above-described problems and can improve the cooling effect of the rotor.

  In order to achieve the above object, the present invention provides a sealed motor in which a stator is provided in a sealed casing and a rotor is rotatably provided inside the stator through an air gap. The surface is provided with a spiral thread groove for allowing the inside air in the sealed casing to flow, and the rotor is provided with a through hole for allowing the inside air in the sealed casing to flow in the axial direction. .

  Preferably, the thread groove is formed continuously along the outer peripheral surface of the rotor, and one end of the thread groove faces one side of the sealed casing and the other end faces the other side of the sealed casing. .

  Preferably, a plurality of the through holes are provided at intervals in the circumferential direction of the rotor.

  According to the present invention, an excellent effect that the cooling effect of the rotor can be enhanced is exhibited.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The hermetic motor of this embodiment will be described with reference to FIGS.

  As shown in FIG. 1, the hermetic motor 1 of the present embodiment includes a stator 3 in a hermetic casing 2 and a rotor 5 that is rotatably provided inside the stator 3 via an air gap 4. Configured.

  The sealed casing 2 includes a casing body 10 formed in a cylindrical shape (cylindrical shape in the illustrated example) whose one end (right end in FIG. 1) is open, and a lid portion 11 that closes the one end of the casing body 10. . On the outer peripheral portion of the casing body 10, a heat radiating means (not shown) (for example, a water cooling device) for radiating the heat transmitted from the stator 3 or the like to the outside is provided.

  The stator 3 is provided along the inner peripheral surface of the casing body 10 of the sealed casing 2. The stator 3 includes a stator core 12 formed by superposing thin metal plates (for example, electromagnetic steel plates) in the axial direction, and a winding 13 wound around the stator core 12.

  The rotor 5 includes a rotor shaft 21 that is rotatably supported by a bearing 20 on the hermetic casing 2, and a rotor body 22 that is fixed to the rotor shaft 21. A plurality of permanent magnets (not shown) are arranged on the outer peripheral portion of the rotor body 22 at intervals in the circumferential direction. A protective cylinder 6 that covers the rotor body 22 is provided on the outer periphery of the permanent magnets, and the outer peripheral surface of the protective cylinder 6 and the inner peripheral surface of the stator 3 face each other with an air gap 4 at a predetermined interval. .

  As shown in FIGS. 1 and 2, in the present embodiment, the inside air (air in the present embodiment) in the sealed casing 2 is axially applied to the outer peripheral surface (outer surface) of the protective cylinder 6 of the rotor 5. A spiral thread groove 7 is provided for flow through the The screw-like groove 7 is composed of a single groove formed continuously along the outer peripheral surface of the protective cylinder 6. One end of the threaded groove 7 faces one end of the sealed casing 2, and the other end faces the other end of the sealed casing 2. That is, the screw-like groove 7 is formed over the entire area of the rotor 5 in the axial direction, and both ends thereof are opened at both ends of the rotor 5. Note that the pitch, depth, width, and number of threads of the thread-like groove 7 are not limited to those of the present embodiment, and are appropriately set in consideration of the interval of the air gap 4 and the rotational speed of the rotor 5. Is done.

  The rotor 5 is provided with a through hole 8 for allowing the inside air in the sealed casing 2 to flow in the axial direction. In the present embodiment, the plurality of through holes 8 are provided at intervals in the circumferential direction (in the figure, four at intervals of about 90 °). These through holes 8 are formed at radial positions so as to penetrate the permanent magnet of the rotor body 22. Each through hole 8 has a circular cross section and is formed to extend from one end of the rotor body 22 to the other end. In addition, the cross-sectional shape and the number of the through holes 8 are not limited to those of the present embodiment.

  Moreover, as shown in FIG. 1, in this embodiment, the sealed space in the hermetic casing 2 is divided into two in the axial direction by the rotor 5 and the stator 3, and these two are partitioned. The spaces S <b> 1 and S <b> 2 communicated with each other through an air gap 4 provided between the stator 3 and the rotor 5 and a through hole 8 provided in the rotor 5.

  Next, the operation of the hermetic motor 1 of the present embodiment will be described.

  When the winding 13 of the stator 3 is energized, a rotating magnetic field is formed in the hermetic motor 1, and the rotor 5 is rotated by the rotating magnetic field. Since the screw-shaped groove 7 is formed on the outer peripheral surface of the rotor 5, the air in the hermetic casing 2 flows between the outer peripheral surface of the rotor 5 and the inner peripheral surface of the stator 3 according to the so-called screw pump principle. (Air gap 4) flows in the axial direction (from right to left in FIG. 1). More specifically, the air flows while turning around the surface of the rotor 5 along the threaded groove 7.

  The air flowing through the air gap 4 takes heat from the rotor 5 side and dissipates the heat to the stator 3 side. That is, heat is transmitted from the rotor 5 to the stator 3 through the air flowing through the screw-like groove 7. Thereby, the rotor 5 is cooled in the forced convection state by the air in the sealed casing 2. On the other hand, the air discharged through the air gap 4 and discharged into the space S1 is radiated and cooled by exchanging heat with the sealed casing 2.

  Further, air is transferred from one space S2 partitioned in the hermetic casing 2 to the other space S1 (from the right side to the left side in FIG. 1) by the screw-shaped groove 7, so that the spaces S1 and S2 are transferred. A pressure difference occurs. Due to the pressure difference, an air flow is formed in the through hole 8 in the direction opposite to the flow direction by the screw-like groove 7 (from the left side to the right side in FIG. 1). With this flow, the air in the other space S1 flows through the through hole 8, and the rotor 5 and its permanent magnet are cooled from the inside. In addition, the air discharged through the through hole 8 into the one space S <b> 2 exchanges heat with the hermetic casing 2 to be radiated and cooled, and is then sucked into the air gap 4 again.

  As described above, the air in the sealed casing 2 is circulated by the air flow through the threaded groove 7 and the air flow in the through hole 8, and cooling of the rotor 5 is promoted. That is, the air in the sealed casing 2 radiates heat of the rotor 5 to the stator 3 and the sealed casing 2 while circulating through the surface and inside of the rotor 5, thereby cooling the rotor 5.

  As described above, in the present embodiment, the air in the sealed casing 2 is caused to flow in the air gap 4 between the rotor 5 and the stator 3 in the axial direction, whereby the heat of the rotor 5 and the stator 3 and the air. Exchange efficiency can be improved. As a result, the amount of heat radiation from the rotor 5 to the stator 3 increases, and the cooling effect of the rotor 5 can be enhanced.

  Furthermore, by providing the through hole 8, the air circulates in the hermetic casing 2, and the cooling efficiency of the rotor 5 can be further improved.

  In addition, by flowing air along the threaded groove 7, the outer periphery of the rotor 5 can be cooled over substantially the entire area, and the air flows while swirling around the outer periphery of the rotor 5. Is longer than the case where the air flows linearly along the axial direction, and the heat exchange efficiency between the air and the rotor 5 and the stator 3 can be improved.

  Further, when air flows through the through hole 8 of the rotor 5, the rotor 5 and the permanent magnet can be cooled from the inner peripheral side (rotor shaft 21 side), and the cooling effect of the rotor 5 and the permanent magnet can be reduced. Can be increased.

  As described above, by improving the cooling effect of the rotor 5 and its permanent magnets, the hermetic motor can be reduced in size and capacity.

  In addition, since the threaded groove can be easily processed by a lathe or the like, the manufacturing cost of the hermetic motor can be reduced.

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

  For example, in the present embodiment, the through hole is provided in the rotor body, but the present invention is not limited to this and may be provided in the protective cylinder.

  Further, it is conceivable to form the through hole in a spiral shape in the opposite direction to the threaded groove. In this case, since the through hole itself actively flows air, circulation of air in the hermetic casing is promoted, and the cooling efficiency of the rotor can be improved.

1 is a schematic view of a hermetic motor according to an embodiment of the present invention. It is a perspective view of the rotor of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing motor 2 Sealing casing 3 Stator 4 Air gap 5 Rotor 7 Screw-shaped groove 8 Through-hole

Claims (3)

In a hermetic motor in which a stator is provided in a hermetic casing and a rotor is rotatably provided inside the stator via an air gap.
A spiral screw-like groove for flowing the inside air in the sealed casing is provided on the outer peripheral surface of the rotor, and a through-hole for circulating the inside air in the sealed casing in the axial direction is provided in the rotor. A sealed motor characterized by being provided.   The threaded groove is formed continuously along the outer peripheral surface of the rotor, and one end of the threaded groove faces one side of the sealed casing, and the other end faces the other side of the sealed casing. Hermetic motor. The hermetic motor according to claim 1, wherein a plurality of the through holes are provided at intervals in the circumferential direction of the rotor.

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