JP2019004638A - Electric motor and heat sink device using the same - Google Patents

Abstract

To achieve a longer service life of an electric motor used for a heat sink device or the like.SOLUTION: An electric motor comprises: a frame having a cylindrical frame housing which is opened at one end; a sleeve embedded in the frame housing; a stator attached to an outer periphery of the frame housing; and a rotor which has a rotation axis 9 rotatably journaled to the sleeve at one end fixed and multiple magnets disposed opposing the stator. The rotation axis 9 is formed with a tapered portion 9d in a central area thereof, a diameter of which is reduced toward a front end portion 9a. Oil is filled in a gap between the rotation axis 9 and the sleeve.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric motor and a heat sink device using the same.

  A heat sink device is attached to the electronic device for cooling. In the heat sink device, a fan is rotated by an electric motor to create an air flow, and heat is taken from the heating element to be cooled.

  Patent Document 1 discloses an invention of a motor (spindle motor) for the purpose of achieving small size, impact resistance, low noise, and low power consumption.

JP-A-6-269142

  In recent years, heat sink devices have come to be used in a wide range of fields such as medical equipment, and a longer life is required.

  One aspect of the present disclosure discloses an electric motor that can have a longer life than a conventional one and a heat sink device using the same.

  An electric motor according to an aspect of the present disclosure includes a frame including a cylindrical frame housing that is open at one end, a sleeve that is fitted in the frame housing, and a stator that is attached to an outer peripheral portion of the frame housing. A rotor having a one-end fixed rotation shaft rotatably supported by the sleeve and a magnet disposed to face the stator, and a central portion of the rotation shaft is provided at a distal end side of a free end. A tapered portion having a reduced diameter is formed, and oil is filled in a gap between the rotating shaft and the sleeve.

  According to the present disclosure, it is possible to achieve a longer life than in the past.

Sectional drawing of the electric motor part of the heat sink apparatus which concerns on one embodiment of this indication Outline drawing of rotating shaft of electric transmitter according to an embodiment of the present disclosure

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

  The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(One embodiment)
<Configuration of motor>
FIG. 1 is a cross-sectional view of a motor portion of a heat sink device according to an embodiment. The frame 1 is assembled with a cylindrical frame housing 1a having one end opened. A stator 3 and a substrate 4 of an electric motor are attached to the outer peripheral portion of the frame housing 1a. The stator 3 includes an insulating portion 14 formed of an insulating material such as synthetic resin, an iron core 15 in which a plurality of thin plates are stacked, and a coil 16 wound around the iron core 15.

  The side wall of the frame 1 is provided with a predetermined number and a predetermined size of openings (not shown) through which an air flow passes in a predetermined direction. Further, the bottom of the frame 1 on the side where the frame housing 1a is not provided has a flat area to which a heating element such as a semiconductor element can be attached. A resin thruster 5 is fixed to the bottom surface of the frame housing 1a.

  A sleeve 6 is fitted in the frame housing 1a, and a fixing ring 7 for pressing the sleeve 6 is inserted. The periphery on the insertion side of the fixing ring 7 is directed inward with an inclination of, for example, about 10 °, and is considered so that it can be easily press fitted into the frame housing 1a.

  The fan 8 includes a rotor body 10 and a blade (not shown) of the electric motor. A rear end 9b of the rotary shaft 9 is inserted and fixed at the center of the rotor body 10. A magnet 11 and a magnet yoke 12 are fixed to the rotor body 10 by adhesion or the like so as to face the annular stator 3. The rotor of the electric motor includes a rotating shaft 9, a rotor body 10, a magnet 11 and a magnet yoke 12.

  Further, the rotor body 10 is formed with a concave oil pool 10 a around the rotating shaft 9 to make it difficult for dust and dirt from the outside to enter the inside of the bearing. The rotor body 10 is formed with a rib 10b on the outer periphery of the oil pool 10a and inside the fixing ring 7.

  The rotary shaft 9 is rotatably supported by the sleeve 6. A dynamic pressure generating groove (not shown) for smoothly rotating the rotary shaft 9 is formed on the inner peripheral surface of the sleeve 6 by ball rolling or the like. The dynamic pressure generating groove is filled with oil 13 as lubricating oil, and forms a radial bearing while maintaining a bearing clearance of 2 to 12 μm on one side with the rotary shaft 9. The dynamic pressure generating grooves may be formed on the outer peripheral surfaces of the first straight portion 9e and the second straight portion 9f (see FIG. 2) of the rotating shaft 9.

  A front end portion 9a (a free end opposite to the rear end portion 9b) of the rotating shaft 9 is finished into a spherical surface, and abuts against the thruster 5 to constitute a thrust bearing.

  Between the frame housing 1a and the sleeve 6, a ventilation groove 1b extending from the opening of the frame housing 1a to the bottom surface is formed on the inner wall of the frame housing 1a. Further, a circumferential groove oil pool 6 a is formed on the outer peripheral surface of the sleeve 6.

  According to the electric motor having such a configuration, the excess oil 13 in the bearing can be accumulated in the oil pool 6a on the outer periphery of the sleeve through the ventilation groove 1b, and the amount of oil injection can be increased and the variation allowable amount can be reduced.

  The sleeve 6 is made of a copper alloy such as C3604 or BC6C in consideration of machinability and rollability, and the rotating shaft 9 is made of stainless steel such as SUS420J2 in consideration of wear resistance and handleability. Steel is used. The oil 13 is made of a fluorinated synthetic oil so that it can withstand high temperatures, and an additive is added to slightly improve the extreme pressure.

  In the heat sink device of the present embodiment, when the rotor of the electric motor rotates, the fan 8 (blade) also rotates and sucks air along the axial direction of the rotating shaft 9 of the electric motor. The sucked air is exhausted from an opening provided in the side wall of the frame 1. At this time, the air flow takes heat from the frame 1 through which the heat of the heating element is conducted. Thereby, a heat generating body is cooled.

<Shape and dimensions of rotating shaft 9>
Next, the shape and dimensions of the rotating shaft 9 will be described with reference to FIG. In addition, the example of the rotating shaft 9 shown to Fig.2 (a)-(e) mutually differs in a taper angle.

  The rotating shaft 9 has a straight cylindrical shape with a constant diameter. The tip 9a at the free end of the rotating shaft 9 is finished into a spherical surface. A knurling process for attaching to the rotor body 10 is performed on the rear end portion 9 b of the rotating shaft 9.

  Further, a taper portion 9d having a tapered shape whose diameter is reduced toward the tip portion 9a side is formed at the center portion (portion where no dynamic pressure is generated) of the rotating shaft 9. As a result, the base portion 9c (the portion other than the front end portion 9a and the rear end portion 9b) of the rotating shaft 9 is a tapered portion 9d, a first straight portion 9e close to the front end portion 9a, and a second straight portion 9f close to the rear end portion 9b. It is divided into. A constricted portion 9g is formed at the connecting portion between the tapered portion 9d and the first straight portion 9e. Further, a constricted portion 9h is formed at a connecting portion between the rear end portion 9b and the second straight portion 9f.

  Dynamic pressure generating grooves may be formed on the outer peripheral surfaces of the first straight portion 9e and the second straight portion 9f.

  The total length of the rotating shaft 9 is, for example, 9 mm, and the outer diameter is, for example, 1.2 mm. The length of the first straight portion 9e is, for example, 1.4 mm, the length of the tapered portion 9d including the constricted portion 9g is, for example, 2.2 mm, and the length of the second straight portion 9f is, for example, 2.9 mm.

<Effect>
As described above, according to the present embodiment, the tapered portion 9d is formed in the central portion of the rotating shaft 9 of the electric motor. Thereby, the oil 13 can be familiarized with the portion (second straight portion 9 f) of the rotating shaft 9 on the rotor body 10 side by the capillary force, so that it is possible to achieve a longer life than the conventional one.

  In order to demonstrate this effect, the inventors of the present invention have a rotating shaft 9 with a tapered portion 9d shown in FIG. 2 and a stepped portion in which a concave groove (depth of about 0.1 mm) is formed instead of the tapered portion 9d. Durability tests were conducted using a rotating shaft of

  As a result of the test under the same conditions, in the environment where the outside air temperature is 120 ° C., the life of the apparatus when using the stepped rotating shaft was about 1200 hours, whereas the rotating shaft 9 with the tapered portion 9d The lifetime of the device when using was about 2200 hours. Further, in the environment where the outside air temperature is 100 ° C., the life of the apparatus when the stepped rotary shaft is used is about 2000 hours, whereas when the rotary shaft 9 with the tapered portion 9d is used. Even if operated for more than 8000 hours, no malfunction occurred in the device.

  As a result of verifying the capillary force, it was found that the taper angle of the taper portion 9d is particularly preferably 1 ° to 3 ° (FIGS. 2A, 2B, and 2C).

  Further, in the central portion of the rotating shaft 9 (portion where no dynamic pressure is generated), instead of the tapered portion 9d, a stepped portion having a multi-stepped shape whose diameter decreases toward the tip portion 9a side may be formed. It was found that the same effect can be obtained.

  While various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the dimension of the rotating shaft 9 is not limited to that described above. The rotary shaft 9 has a first straight portion 9e having a length of 1 to 3 mm, a tapered portion 9d including a constricted portion 9g having a length of 0.5 to 4 mm, and a second straight portion 9f having a length of 1 It is created in the range of 5-5mm.

  In addition, the rear end portion 9b of the rotating shaft 9 may not be knurled and the constricted portion 9h may not be formed. In this case, the length of the second straight portion 9f may be 5 mm or more.

  Moreover, although the case where the electric motor is used for the heat sink device has been described in the above embodiment, the present invention is not limited to this and may be used for other devices such as an exhaust fan.

  The present invention is suitable for use in an electric motor and a heat sink device using the same.

DESCRIPTION OF SYMBOLS 1 Frame 1a Frame housing 3 Stator 5 Thruster 6 Sleeve 8 Fan 9 Rotating shaft 9a Tip part 9b Rear end part 9c Base part 9d Tapered part 9e First straight part 9f Second straight part 10 Rotor body 11 Magnet 13 Oil

An electric motor according to an aspect of the present disclosure includes a frame including a cylindrical frame housing that is open at one end, a sleeve that is fitted in the frame housing, and a stator that is attached to an outer peripheral portion of the frame housing. A rotor having a one-end fixed rotation shaft rotatably supported by the sleeve and a magnet disposed opposite to the stator, and the rotation shaft is formed in a columnar shape at a central portion of the rotation shaft. Is formed with a tapered portion having a reduced diameter on the distal end side of the free end, and the length of the tapered portion is longer than the diameter of the rotating shaft, and oil is provided in a gap between the rotating shaft and the sleeve. Is filled.

Claims (7)

A frame having a cylindrical frame housing with one end open;
A sleeve fitted into the frame housing;
A stator attached to the outer periphery of the frame housing;
A rotor having a rotating shaft fixed to one end rotatably supported by the sleeve and a magnet disposed opposite to the stator;
Comprising
In the central portion of the rotating shaft, a tapered portion having a tapered shape that is reduced in diameter toward the distal end side of the free end is formed,
Oil is filled in the gap between the rotating shaft and the sleeve,
Electric motor. The taper angle of the taper portion is 1 ° to 3 °.
The electric motor according to claim 1. The tapered portion is formed by being sandwiched between two straight portions having a constant diameter.
The electric motor according to claim 1 or 2. A frame having a cylindrical frame housing with one end open;
A sleeve fitted into the frame housing;
A stator attached to the outer periphery of the frame housing;
A rotor having a rotating shaft fixed to one end rotatably supported by the sleeve and a magnet disposed opposite to the stator;
Comprising
In the central part of the rotating shaft, a stepped portion having a stepped shape having a plurality of steps whose diameter decreases toward the tip end side of the free end is formed.
Oil is filled in the gap between the rotating shaft and the sleeve,
Electric motor. The stepped portion is formed by being sandwiched between two straight portions having a constant diameter.
The electric motor according to claim 4. A dynamic pressure generating groove for holding the oil is formed on at least one of the outer peripheral surface of the rotating shaft or the inner peripheral surface of the sleeve.
The electric motor according to any one of claims 1 to 5. A cooling fan motor comprising the electric motor according to any one of claims 1 to 6,
A heating element can be attached to the frame of the electric motor.
Heat sink device.

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