JP6390990B1 - Electric motor and heat sink device using the same - Google Patents

Abstract

To extend the life of an electric motor used in a heat sink device or the like.
An electric motor includes a frame having a cylindrical frame housing that is open at one end, a sleeve that is fitted in the frame housing, a stator that is attached to the outer periphery of the frame housing, and a sleeve that is freely rotatable. And a rotor having a magnet disposed so as to face the stator. A taper-shaped first taper portion 9d that is reduced in diameter toward the free end side (tip portion 9a side) and a taper-shaped second taper portion 9e that is increased in diameter toward the free end side are formed at the center of the rotating shaft 9. The The first taper portion 9d is longer than the second taper portion 9e, and the gap between the rotary shaft 9 and the sleeve is filled with oil.
[Selection] 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 is attached to a frame including a cylindrical frame housing that is open at one end, a cylindrical sleeve that is fitted in the frame housing, and an outer peripheral portion of the frame housing. A stator having a single-end fixed rotation shaft rotatably supported by the sleeve and a rotor having a magnet disposed opposite to the stator, the rotation shaft having a cylindrical shape, A taper-shaped first taper portion that decreases in diameter toward the free end side and a taper-shaped second taper portion that increases in diameter toward the free end side are formed in the center portion, and the first taper portion is the second taper portion. It is longer than 1.4 times the taper portion , and oil is filled in the 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 motor part of the heat sink apparatus which concerns on Embodiment 1 of this indication Outline drawing of rotating shaft of electric motor according to Embodiment 1 of present disclosure The figure which shows the evaluation result for every taper part ratio of the rotating shaft of the electric motor which concerns on Embodiment 1 of this indication. Sectional drawing of the motor part of the heat sink apparatus which concerns on Embodiment 2 of this indication Outline drawing of sleeve of electric motor according to embodiment 2 of present disclosure The figure which shows the evaluation result for every taper part ratio of the sleeve of the electric motor which concerns on Embodiment 2 of this indication.

  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.

(Embodiment 1)
<Configuration of motor>
FIG. 1 is a cross-sectional view of an electric motor portion of the heat sink device according to the first 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 9f and the second straight portion 9g (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. An oil pool 6a having a circumferential groove is formed on the distal end side of the outer peripheral surface of the sleeve 6 (side closer to the bottom surface of the frame housing 1a).

  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 of the present embodiment will be described with reference to FIG. In addition, each example of the rotating shaft 9 shown to Fig.2 (a)-(f) makes the ratio of the length of the 1st taper part 9d and the length of the 2nd taper part 9e mutually different.

  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, in the central portion (portion where no dynamic pressure is generated) of the rotating shaft 9, a tapered first tapered portion 9d having a diameter reduced toward the distal end portion 9a side and a tapered second shape having a diameter increased toward the distal end portion 9a side. A tapered portion 9e is formed. As a result, the base portion 9c (portion other than the front end portion 9a and the rear end portion 9b) of the rotating shaft 9 includes a first taper portion 9d, a second taper portion 9e, a first straight portion 9f close to the front end portion 9a, and a rear end portion. It is divided into second straight portions 9g close to 9b. In addition, you may form the 3rd straight part 9h in the connection part of the 1st taper part 9d and the 2nd taper part 9e for reasons, such as ease of a process. Further, a constricted portion 9i is formed at a connecting portion between the rear end portion 9b and the second straight portion 9g.

  A region including the first tapered portion 9d, the second tapered portion 9e, and the third straight portion 9h (hereinafter referred to as “tapered region”) serves as an oil pool.

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

  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 9f is, for example, 1.4 mm, the length of the tapered region is, for example, 2.2 mm, and the length of the second straight portion 9g is, for example, 2.8 mm.

<Verification of capillary force>
The present inventors verified the capillary force for each rotating shaft 9 shown in FIGS. The evaluation results are shown in FIG.

  The first taper portion 9d is longer than the second taper portion 9e, that is, the length of the first taper portion 9d relative to the length of the second taper portion 9e ("A" in FIGS. 2 and 3) (FIG. 2, When the ratio of “B” in FIG. 3 is larger than 1 (FIGS. 2 (c), (d), (e), (f)), the bubbles in the tapered region are moved to the tip portion 9a side. It was found that the oil 13 in the tapered region can be moved to the rotor body 10 side of the rotary shaft 9 by capillary force (the evaluation in FIG. 3 is “◯” or “Δ”). Further, it has been found that the taper angle of the first taper portion 9d is particularly preferably 1 ° to 10 °.

  Further, when the first taper portion 9d is made shorter than the second taper portion 9e, that is, when the ratio of the length of the first taper portion 9d to the length of the second taper portion 9e is made smaller than 1 (FIG. 2 (a)), it was found that the bubbles in the tapered region moved to the rotor body 10 side, and the oil 13 in the tapered region could not be moved to the rotor body 10 side (the evaluation in FIG. 3 is "X").

  In addition, when the length of the first taper portion 9d is substantially equal to the length of the second taper portion 9e (FIG. 2B), the bubbles in the taper region do not move, and the oil 13 in the taper region is sufficient. In addition, it was found that the rotor main body 10 cannot be moved (the evaluation in FIG. 3 is “x”).

<Effect>
As described above, in the present embodiment, at the central portion of the rotating shaft 9 of the electric motor, the first taper portion 9d whose diameter decreases toward the tip portion 9a side, and the second taper portion 9e whose diameter increases toward the tip portion 9a side, The first taper portion 9d is made longer than the second taper portion 9e. Thereby, the oil 13 can be familiarized with the portion (second straight portion 9g) of the rotating shaft 9 on the rotor main body 10 side by the capillary force, so that it is possible to achieve a longer life than the conventional one.

  In the present embodiment, the dimensions of each part of the rotating shaft 9 are not limited to those described above. The rotary shaft 9 has a first straight portion 9f having a length of 1.5 to 10 mm, a tapered region having a length of 0.5 to 4 mm, and a second straight portion 9g having a length of 1 to 8 mm. Created with.

  Further, the connecting portion between the first tapered portion 9d and the second tapered portion 9e may have a shape other than the third straight portion 9h, such as a tapered portion or a constricted portion.

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

(Embodiment 2)
In the first embodiment, the case where the first taper portion 9d and the second taper portion 9e are provided on the rotating shaft 9 has been described. In the second embodiment, a case where the sleeve 6 is provided with the first tapered portion 6d and the second tapered portion 6e (see FIG. 5) will be described.

<Configuration of motor>
FIG. 4 is a cross-sectional view of a motor portion of the heat sink device of the second embodiment. The heat sink device shown in FIG. 4 differs from the heat sink device shown in FIG. 1 in the shapes of the sleeve 6 and the rotating shaft 9.

  In the present embodiment, a taper region is not formed on the rotating shaft 9, and the entire base portion 9c is a straight portion.

<Shape and dimension of sleeve 6>
Next, the shape and dimensions of the sleeve 6 of the present embodiment will be described with reference to FIG. In each example of the sleeve 6 shown in FIGS. 5A to 5F, the ratio of the length of the first taper portion 6d and the length of the second taper portion 6e is different from each other.

  The sleeve 6 has a cylindrical shape, and an oil pool 6a having a circumferential groove is formed on the front end side of the outer circumferential surface, and a stepped portion 6b of the circumferential groove is formed on the rear end side of the outer circumferential surface.

  In addition, a taper-shaped first taper portion 6d that increases in diameter toward the distal end side and a taper-shaped second taper that decreases in diameter toward the distal end side are provided at the central portion (portion where no dynamic pressure is generated) of the inner peripheral surface of the sleeve 6. A portion 6e is formed. Thereby, the inner peripheral surface of the sleeve 6 is divided into a first taper portion 6d, a second taper portion 6e, a first straight portion 6f on the front end side, and a second straight portion 6g on the rear end side. In addition, you may form the 3rd straight part 6h in the connection part of the 1st taper part 6d and the 2nd taper part 6e for reasons, such as ease of a process.

  A region including the first tapered portion 6d, the second tapered portion 6e, and the third straight portion 6h (hereinafter referred to as “tapered region”) serves as an oil pool.

  A dynamic pressure generating groove 6c is formed on the outer peripheral surfaces of the first straight portion 6f and the second straight portion 6g.

  The total length of the sleeve 6 is, for example, 6.0 mm, the outer diameter is, for example, 4.0 mm, and the inner diameter is, for example, 1.2 mm. The length of the first straight portion 6f is, for example, 1.8 mm, the length of the tapered region is, for example, 2.0 mm, and the length of the second straight portion 6g is, for example, 2.2 mm.

<Verification of capillary force>
The inventors verified the capillary force of each sleeve 6 shown in FIGS. The evaluation results are shown in FIG.

  The first taper portion 6d is made longer than the second taper portion 6e, that is, the length of the first taper portion 6d with respect to the length of the second taper portion 6e ("A" in FIGS. 5 and 6) (FIG. 5, When the ratio of “B” in FIG. 6 is larger than 1 (FIGS. 5C, 5D, 5E, and 5F), the bubbles in the tapered region are moved to the tip side, and the taper It was found that the oil 13 in the region can be moved to the rotor body 10 side of the rotary shaft 9 by capillary force (evaluation in FIG. 6 is “◯” or “Δ”). Further, it has been found that the taper angle of the first taper portion 6d is particularly preferably 1 ° to 10 °.

  Further, when the first taper portion 6d is made shorter than the second taper portion 6e, that is, when the ratio of the length of the first taper portion 6d to the length of the second taper portion 6e is made smaller than 1 (FIG. 5 (a)), it was found that the bubbles in the tapered region moved to the rotor body 10 side, and the oil 13 in the tapered region could not be moved to the rotor body 10 side (the evaluation in FIG. 6 is "X").

  In addition, when the length of the first taper portion 6d is substantially equal to the length of the second taper portion 6e (FIG. 5B), the bubbles in the taper region do not move, and the oil 13 in the taper region is sufficiently discharged. In addition, it was found that the rotor main body 10 cannot be moved (the evaluation in FIG. 6 is “x”).

<Effect>
As described above, in the present embodiment, the first taper portion 6d that increases in diameter toward the distal end side of the rotating shaft 9 and the second taper that decreases in diameter toward the distal end side of the rotating shaft 9 at the central portion of the sleeve 6 of the electric motor. Part 6e, and the first taper part 6d is made longer than the second taper part 6e. Thereby, the oil 13 can be familiarized with the portion (second straight portion 9g) of the rotating shaft 9 on the rotor main body 10 side by the capillary force, so that it is possible to achieve a longer life than the conventional one.

  In the present embodiment, the dimensions of each part of the sleeve 6 are not limited to those described above. In the sleeve 6, the length of the first straight portion 6f is in the range of 1.5 to 10 mm, the length of the tapered region is in the range of 0.5 to 4 mm, and the length of the second straight portion 6g is in the range of 1 to 8 mm. Created.

  Further, the connecting portion between the first tapered portion 6d and the second tapered portion 6e may have a shape other than the third straight portion 6h, such as a tapered portion or a constricted portion.

  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, in each of the above embodiments, the case where the electric motor is used for the heat sink device has been described. However, 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 6c Dynamic pressure generating groove 6d 1st taper part 6e 2nd taper part 6f 1st straight part 6g 2nd straight part 6h 3rd straight part 7 Fixing ring 8 Fan 9 Rotating shaft 9a Front end portion 9b Rear end portion 9c Base portion 9d First taper portion 9e Second taper portion 9f First straight portion 9g Second straight portion 9h Third straight portion 9i Constriction portion 10 Rotor body 11 Magnet 12 Magnet yoke 13 Oil

Claims (7)

A frame having a cylindrical frame housing with one end open;
A cylindrical 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
The rotation axis has a cylindrical shape,
A taper-shaped first taper portion that is reduced in diameter toward the free end side and a taper-shaped second taper portion that is increased in diameter toward the free end side are formed in the central portion of the rotating shaft,
The first taper portion is longer than 1.4 times the second taper portion,
Oil is filled in the gap between the rotating shaft and the sleeve,
Electric motor. The taper angle of the first taper portion is 1 ° to 10 °,
The electric motor according to claim 1. The length obtained by adding the first tapered portion and the second tapered portion is longer than the diameter of the rotating shaft.
The electric motor according to claim 1 or 2. A frame having a cylindrical frame housing with one end open;
A cylindrical 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
The rotation axis has a cylindrical shape,
A taper-shaped first taper portion that expands toward the free end of the rotating shaft and a taper-shaped second taper portion that decreases in diameter toward the free end are formed at the center of the inner peripheral surface of the sleeve. ,
The first taper portion is longer than 1.4 times the second taper portion,
Oil is filled in the gap between the rotating shaft and the sleeve,
Electric motor. The taper angle of the first taper portion is 1 ° to 10 °,
The electric motor according to claim 4. The length obtained by adding the first tapered portion and the second tapered portion is longer than the diameter of the rotating shaft.
The electric motor according to claim 4 or 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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