JP4036196B2 - Electric motor and heat sink device using the same - Google Patents

Description

  The present invention relates to an electric motor using a dynamic pressure type fluid bearing and a heat sink device using the same.

  7 and 8 show a configuration of a heat sink device using a conventional dynamic pressure type fluid bearing electric motor. 7 is a sectional view showing a conventional heat sink device for cooling a semiconductor, FIG. 8 is a sectional view showing a bearing portion of an electric motor used in the heat sink device of FIG. 7, and FIG. 9 is a deformation state of a sleeve in the electric motor of FIG. It is a graph which shows.

  As shown in FIG. 7, a drive circuit board 4 in which a hall element or the like is provided on a stator 3 around which a coil 2 is wound is installed around a cup-shaped frame housing 1 a that is formed to protrude from a recess of the frame 1. ing. The stator 3 is fixed to the outer peripheral portion of the frame housing 1 a, and an insulating sheet 20 is installed between the drive circuit board 4 and the frame 1. A thruster 5 made of resin or the like is fixed to the bottom surface of the frame housing 1a, and a bell mouth 19 for smoothing the air flow is fixed to the outer periphery of the frame 1. A sleeve 6 is press-fitted and fixed to the frame housing 1 a to constitute a stator unit 15.

  A shaft 9 is integrally formed with the fan 8, and a washer 10 for preventing the fan 8 from being detached is attached to the shaft 9. The shaft 9 is in contact with the thruster 5 and is fitted to the sleeve 6 so as to be rotatable. Further, a magnet 11 and a magnet yoke 12 are fixed to the fan 8 so as to face the annular stator 3, thereby constituting a rotor 16.

  As shown in FIG. 8, a dynamic pressure generating groove 13 is formed on the inner peripheral surface of the sleeve 6 by ball rolling or the like, and the protrusion generated by the ball rolling is removed to increase the sleeve inner diameter to ± 2 μm or less. Sizing is performed to finish with accuracy.

The dynamic pressure generating groove 13 is filled with an oil 14 as a lubricating oil to constitute a radial bearing 17. Further, the end surface of the shaft 9 on the side opposite to the fan 8 is finished into a spherical surface and constitutes a thrust bearing 18 in contact with the thruster 5.
JP-A-6-269142

  However, such a conventional electric motor has the following problems.

  In recent years, downsizing is progressing in electronic devices such as personal computers and home appliances, and accordingly, heat sink devices and electric motors such as cooling fan motors attached to the electronic devices are required to be reduced in size and thickness.

Due to the miniaturization and thinning of the electric motor, the space of the bearing portion is very small, and the thickness of the sleeve 6 is inevitably reduced. Further, the allowance for press-fitting between the sleeve 6 and the frame housing 1a is 20 μm or more in consideration of processing variations. As shown in FIG. 9, when the sleeve 6 is press-fitted and fixed, the inner diameter of the sleeve 6 is affected by deformation or the like. It has occurred. Due to the deformation of the inner diameter of the sleeve 6, the gap between the shaft 9 and the sleeve 6 becomes non-uniform, the pumping force of the dynamic pressure generating groove 13 decreases, the swing of the shaft 9 increases, the contact between the shaft 9 and the sleeve 6, The oil 14 was caused to flow out, and the reliability of the bearing was lowered.

  In addition, the amount of heat generated by electronic devices, etc. is increasing due to high performance and downsizing. Accordingly, motors used for heat sink devices and cooling fans attached to electronic devices, etc., rotate at high speed to enhance the cooling effect. Is becoming necessary.

  In contrast, the bearing oil 14 held by the surface tension of the gap between the shaft 9 and the sleeve 6 causes the excess oil to flow out without being able to withstand the centrifugal force due to the high speed rotation, and further flows out the excess oil. As a result, the necessary oil component flows through the shaft 9 and the rotor 16 and flows out. For this reason, the oil shortage of the bearing eventually occurs, the rotational speed decreases, the current value increases or abnormal noise occurs, and further, the rotor 16 is locked and the reliability is impaired. It was.

Therefore, according to the present invention, since the fixing ring easily bites into the sleeve, the fixing force of the sleeve to the fixing ring is increased, the sleeve is not loosened due to thermal shock, vibration or drop impact, and the sleeve rotates and vibrates with the shaft of the sleeve. An object of the present invention is to provide an electric motor capable of effectively preventing an increase in the number of bits and seizure of a bearing.

In order to solve this problem, an electric motor of the present invention is supported at one end by a frame having a frame housing, a stator attached to an outer peripheral portion of the frame housing, and a receiving seat formed in the frame housing. And a rotor including a sleeve fitted in, a fixing ring for sandwiching the sleeve between the receiving seat, a shaft rotatably fitted in the sleeve, and a magnet arranged to face the stator The fixing ring is made of a material harder than the sleeve, and has a concave-convex shape on the side in contact with the sleeve, and the convex portion of the fixing ring bites into the sleeve . Is press-fitted into .

This makes it easier for the fixing ring to bite into the sleeve, increasing the fixing force of the sleeve to the fixing ring, eliminating the loosening of the sleeve due to thermal shock, vibration and drop impact, co-rotating with the sleeve axis, increasing vibration, It is possible to effectively prevent bearing seizure and improve the reliability of the bearing.

According to the first aspect of the present invention, one end is supported by a frame having a frame housing, a stator attached to the outer periphery of the frame housing, and a receiving seat formed in the frame housing. a sleeve fitted Te, a fixing ring sandwiched between the seat receiving the sleeve, the shaft fitted in the rotatable sleeve, and the electric motor having a rotor provided with oppositely disposed magnet stator, fixed The ring is made of a material harder than the sleeve and has a concave-convex shape on the side in contact with the sleeve. The ring is pressed into the frame housing so that the convex portion of the fixing ring bites into the sleeve . As a result, the fixing ring easily bites into the sleeve, so that the fixing force of the sleeve to the fixing ring is increased, and the sleeve is prevented from loosening due to thermal shock, vibration or drop impact.

According to the second aspect of the present invention, in the first aspect of the invention, the fixing ring is made of stainless steel and the sleeve is made of a copper alloy, so that the fixing ring easily bites into the sleeve. In addition to the effect that the fixing force to the fixing ring increases, the spring property and workability of the fixing ring are improved.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In these drawings, the same members are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
1 is a sectional view showing a heat sink device according to Embodiment 1 of the present invention, FIG. 2 is a sectional view showing a bearing portion of an electric motor used in the heat sink device of FIG. 1, and FIG. 3 is a fixing ring attached to the electric motor of FIG. FIG. 4 is a graph showing the amount of deformation of the sleeve inner diameter in the electric motor of FIG. 1 and the conventional electric motor.

  Including the embodiment described below, the electric motor in the present embodiment is used for a heat sink device for cooling a semiconductor, and as shown in FIG. Around the frame housing 1a, there is installed a drive circuit board 4 in which a hall element or the like is provided on a stator 3 around which a coil 2 is wound. Plate-shaped or pin-shaped fins 21 are erected in the recesses of the frame 1, and openings (not shown) through which air flows pass on the side walls in a predetermined direction with a predetermined number and a predetermined size. Is provided. 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. The stator 3 is fixed to the outer peripheral portion of the frame housing 1 a, and an insulating sheet 20 is installed between the drive circuit board 4 and the frame 1. A thruster 5 made of resin or the like is fixed to the bottom surface of the frame housing 1a, and a bell mouth 19 for smoothing the air flow is fixed to the side wall of the frame 1.

  A receiving seat 1b is formed in the frame housing 1a, and supports one end of a sleeve 6 fitted in the frame housing 1a. The sleeve 6 is inserted into the frame housing 1a with a gap of 0.1 mm or less, or is lightly press-fitted with a fastening allowance of 5 μm or less. A fixing ring 7 (FIG. 3) that holds the fitted sleeve 6 against the seat 1 b is inserted into the frame housing 1 a, and constitutes a stator unit 15.

  The periphery of the fixing ring 7 on the insertion side faces 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.

  A shaft 9 is integrally formed with the fan 8, and a washer 10 having a slit is press-fitted on the opposite side of the shaft 9 from the fan 8 to prevent the fan 8 from coming off. The shaft 9 is in contact with the thruster 5 and is rotatably fitted in the sleeve 6. In addition, a magnet 11 and a magnet yoke 12 are fixed to the fan 8 by adhesion or the like so as to face the annular stator 3, thereby constituting a rotor 16.

  Further, a concave oil pool 8a is formed around the base portion of the shaft 9 extending from the fan 8 to receive oil scattered from between the sleeve 6 and the shaft 9 during rotation. The volume of the oil pool 8a is equal to or greater than the volume of the gap between the sleeve 6 and the shaft 9. Further, a rib 8b having a gap of, for example, 50 μm to 300 μm and an overlap length of, for example, 0.3 mm or more is formed on the outer periphery of the oil pool 8a and inside the fixing ring 7 with respect to the fixing ring 7.

  As shown in FIG. 2, two dynamic pressure generating grooves 13 for smoothly rotating the shaft 9 are formed on the inner peripheral surface of the sleeve 6 by ball rolling or the like, and are further generated by ball rolling. Sizing is performed in order to remove the protrusions and finish the sleeve inner diameter with high accuracy of ± 2 μm or less. The dynamic pressure generating groove 13 is filled with oil 14 as lubricating oil, and forms a radial bearing 17 while maintaining a bearing clearance of 2 to 12 μm on one side with the shaft 9. The dynamic pressure generating groove may be formed on the outer peripheral surface of the shaft 9.

  As shown in detail in FIG. 2, the end surface of the shaft 9 on the side opposite to the fan 8 is finished to be spherical, and constitutes a thrust bearing 18 in contact with the thruster 5.

  As the material of the sleeve 6, a copper alloy such as C3604 or BC6C is used in consideration of machinability and rollability, and the shaft 9 is made of stainless steel such as SUS420J2 in consideration of wear resistance and handleability. Is used. Oil 14 is often attached directly to semiconductors and is close to a heat source, so fluorinated synthetic oil is used to withstand high temperatures. Oil 14 is added to improve extreme pressure. An agent has been added.

  According to the fan motor having such a configuration, since the sleeve 6 is fixed in a sandwich state between the receiving seat 1b and the fixing ring 7, the stress applied to the sleeve 6 in the radial direction is reduced. Thereby, as shown in FIG. 4, the deformation amount of the sleeve inner diameter can be reduced to about 1/4 as compared with the conventional fan motor.

  When the sleeve 6 and the frame housing 1a are fitted to each other with a gap of 0.1 mm or more, the sleeve 6 and the stator 3 are misaligned to cause uneven rotation. Further, when press-fitting with a fastening allowance of 5 μm or more, deformation of 0.6 μm or more is caused in the inner diameter of the sleeve 6 (see FIG. 9). For this reason, as described above, in consideration of processing variations, the sleeve 6 and the frame housing 1a are inserted with a gap of 0.1 mm or less, or light press-fitting with a tightening margin of 5 μm or less is performed. ing.

  Further, an oil pool 8a having a volume equal to or larger than a gap between the sleeve 6 and the shaft 9 is formed around the base portion of the shaft 9, and a fixing ring 7 and a rib 8b formed on the outer periphery of the oil pool 8a are formed. Since they face each other with a very narrow gap, excess oil scattered from the bearing during rotation is reliably pooled in the oil pool 8a. This prevents a necessary oil component from flowing out.

  Even if the necessary oil component becomes insufficient due to evaporation or the like, the excess oil component is pooled in the oil pool 8a in the vicinity of the sleeve, so that the excess oil component is supplied to the bearing gap with higher surface tension as needed. As a result, a shortage of oil in the bearing can be prevented.

  Here, when the gap between the rib 8b and the fixing ring 7 is set to 300 μm or more, the surface tension of the oil 14 that has flowed into the gap becomes low, and the oil 14 breaks through the gap. On the other hand, when the thickness is 50 μm or less, the surface tension of the gap is increased and the oil 14 is sucked up, resulting in insufficient oil in the bearing and an increase in the friction torque of the oil. For this reason, the rib 8b on the outer periphery of the oil pool 8a and the fixing ring 7 are disposed between the gaps of 50 μm to 300 μm to effectively prevent the oil 14 from flowing out.

  Next, the operation of the heat sink device of the present embodiment will be described. When the electric motor rotates, the fan 8 also rotates, sucks air along the direction of the motor shaft 9, flows according to the air flow path formed by the fins 21, and is exhausted from the opening provided on the side wall of the frame 1. . At this time, the air flow takes heat from the frame 1 and the fins 21 through which the heat of the heating element is conducted, and performs a cooling action. The direction of the opening of the side wall is in accordance with the electronic device using the heat sink device in order to apply the air exhausted from the heat sink device to other heating elements and to smoothly exhaust the hot air from the electronic device device. Open in one direction or multiple directions.

The shape of the fin 21 is not limited to a plate shape or a pin shape, and may be any shape that exhibits the same action and effect such as a triangular shape, a wing shape, a spiral shape, a circular shape, and a radial shape. When the heat sink device is smaller than a predetermined size (40 mm square), the size of the electric motor is inevitably small, and as a result, the output of the electric motor is also small. Therefore, in the above case, the wind force generated by the electric motor and the fan becomes small, and when the fins are erected, the amount of air discharged becomes small, which may worsen the heat dissipation effect. Thus, when the size of the heat sink device is in the above range, it is preferable not to stand the fins, but to increase the amount of air discharged to improve the heat dissipation effect.

(Embodiment 2)
FIG. 5 is a sectional view showing a fixing ring attached to the electric motor according to Embodiment 2 of the present invention.

  Unlike the first embodiment, the fixing ring 7 according to the present embodiment has an uneven end surface on the side in contact with the sleeve 6.

  By making the fixing ring 7 have such an uneven shape, the convex portion of the fixing ring 7 bites into the sleeve 6 when the fixing ring 7 is press-fitted. Accordingly, the fixing force of the sleeve 6 is further increased, and the sleeve 6 is not loosened due to thermal shock, vibration or drop impact, and the sleeve 6 can be effectively prevented from rotating together with the shaft 9, increasing vibration, and bearing seizure. Will come to be.

  For the material of the fixing ring 7, for example, stainless steel such as SUS304 is used in consideration of the spring property and workability, and further considering that it is harder than the sleeve 6 and easily bites into the sleeve 6.

(Embodiment 3)
FIG. 6 is a cross-sectional view showing a heat sink device according to Embodiment 3 of the present invention.

  As shown in FIG. 6, a drive circuit board 4 in which a hall element or the like is provided on a stator 3 around which a coil 2 is wound is installed around a cup-shaped frame housing 1 a that protrudes from a recess of the frame 1. ing. The stator 3 is fixed to the outer peripheral portion of the frame housing 1 a, and an insulating sheet 20 is installed between the drive circuit board 4 and the frame 1. A bell mouth 19 for smoothing the air flow is fixed to the outer periphery of the frame 1. Further, a shaft 9 is fixed in the frame housing 1a. A sleeve 6 is rotatably fitted to the shaft 9. A washer 10 with a slit is press-fitted and attached to the tip of the shaft 9 to prevent the fan 8 from coming off, thereby constituting a stator unit 15.

  Further, a magnet 11 and a magnet yoke 12 are fixed to the fan 8 by adhesion or the like so as to face the annular stator 3, and the sleeve 6 is fitted into a cup-shaped rotor housing 8 c formed to protrude from the fan 8. It is attached.

  Further, a thruster 5 made of resin or the like is fixed in contact with the tip of the shaft 9. A receiving seat 8d is formed in the rotor housing 8c of the fan 8, and supports one end of the sleeve 6 fitted in the rotor housing 8c. The sleeve 6 is inserted into the rotor housing 8c with a gap of 0.1 mm or less, or lightly press-fitted with a fastening allowance of 5 μm or less.

  A fixing ring 7 that presses the fitted sleeve 6 against the seat 8d is inserted into the rotor housing 8c. The rotor 16 constitutes the rotor 16 and is rotatably attached via a bearing.

  The periphery of the fixing ring 7 on the insertion side faces 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.

According to the fan motor having such a configuration, as in the case of the first embodiment, the sleeve 6 is fixed in a sandwich state between the receiving seat 8d and the fixing ring 7, so that the stress applied in the radial direction of the sleeve 6 is reduced. This greatly reduces the deformation of the sleeve inner diameter (see FIG. 4).

  The structure of the heat sink device and the structure of the electric motor used therein, the type of electric motor, the structure of the bearing, the oil, etc. are not limited to the contents of these embodiments, and various design changes are possible. Needless to say. In the above-described embodiment, the dynamic pressure generating groove 13 is formed on the inner peripheral surface of the sleeve 6, but may be formed on the outer peripheral surface of the shaft 9.

  As described above, according to the present invention, since the sleeve is sandwiched and fixed between the receiving seat and the fixing ring, the stress applied in the radial direction of the sleeve is reduced, and deformation of the sleeve inner diameter can be prevented. An effective effect is possible.

  Thereby, smooth operation is possible, and an effective effect that an electric motor having high reliability and a long life can be obtained is obtained.

  By making the end surface of the fixing ring in contact with the sleeve uneven, the convex part of the fixing ring bites into the sleeve, increasing the fixing force of the sleeve, so that the sleeve and the shaft rotate together, vibration increases, the bearing An effective effect that burn-in and the like can be effectively prevented is obtained.

  Further, by inclining the periphery of the insertion side of the fixing ring inward, an effective effect that the fixing ring can be easily inserted into the housing is obtained.

  Furthermore, by forming a dynamic pressure generating groove for retaining oil on either the outer peripheral surface of the shaft or the inner peripheral surface of the sleeve, an effective effect of smooth shaft rotation can be obtained.

Sectional drawing which shows the heat sink apparatus by Embodiment 1 of this invention Sectional drawing which shows the bearing part of the electric motor used for the heat sink apparatus of FIG. Sectional drawing which shows the fixing ring attached to the electric motor of FIG. The graph which shows the deformation | transformation amount of the sleeve internal diameter in the electric motor of FIG. 1 and the conventional electric motor Sectional drawing which shows the fixing ring attached to the electric motor by Embodiment 2 of this invention Sectional drawing which shows the heat sink apparatus by Embodiment 3 of this invention Sectional view showing a conventional heat sink device for semiconductor cooling Sectional drawing which shows the bearing part of the electric motor used for the heat sink apparatus of FIG. The graph which shows the deformation | transformation state of the sleeve in the electric motor of FIG.

Explanation of symbols

1 frame 1a frame housing 1b receiving seat 3 stator 6 sleeve 7 fixing ring 8 fan 8a oil pool 8b rib 8c rotor housing 8d receiving seat 9 shaft 11 magnet 13 dynamic pressure generating groove 14 oil 16 rotor 21 fin

Claims (2)

A frame with a frame housing;
A stator attached to the outer periphery of the frame housing;
A sleeve fitted so that one end is supported by a receiving seat formed in the frame housing;
A fixing ring that sandwiches the sleeve with the seat;
An electric motor having a shaft rotatably fitted in the sleeve and a rotor having a magnet disposed opposite to the stator;
The fixing ring is made of a material harder than the sleeve and has a concave-convex shape on the side in contact with the sleeve, and is press-fitted into the frame housing so that the convex portion of the fixing ring bites into the sleeve. Electric motor. 2. The electric motor according to claim 1, wherein stainless steel is used for the fixing ring and copper alloy is used for the sleeve.

Images