JP2004208498A - Motor and heat sink device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor which can prevent the deformation of the inside of a sleeve, and a heat sink device using it. <P>SOLUTION: This motor has a frame 1 which is equipped with a cup-shaped frame housing 1a, a stator 3 which is attached to the periphery of the frame housing 1a, a sleeve 6 which is set on a seat 1b made within the frame housing 1a so that its one end is supported, a rotor 16 which is equipped with a shaft 9 set rotatably in the sleeve 6 and a magnet 11 facing the stator 3, and a fixed ring 7 which is inserted into the housing 1a and presses the sleeve 6 against the seat 1b. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

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

  FIGS. 7 and 8 show a configuration of a heat sink device using a conventional motor of a dynamic pressure type fluid bearing. 7 is a sectional view showing a conventional heat sink device for cooling semiconductors, FIG. 8 is a sectional view showing a bearing portion of a motor used in the heat sink device of FIG. 7, and FIG. 9 is a deformed state of a sleeve in the motor of FIG. FIG.

  As shown in FIG. 7, around a cup-shaped frame housing 1a protrudingly formed in a concave portion of the frame 1, a drive circuit board 4 provided with a hall element and the like on a stator 3 around which a coil 2 is wound is installed. ing. The stator 3 is fixed to an outer peripheral portion of the frame housing 1a, and an insulating sheet 20 is provided 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 flow of air is fixed to the outer periphery of the frame 1. The sleeve 6 is press-fitted and fixed to the frame housing 1a to form the stator unit 15.

  A shaft 9 is integrally formed with the fan 8, and a washer 10 for preventing the fan 8 from coming off is attached to the shaft 9. The shaft 9 abuts on the thruster 5 and is fitted into the sleeve 6 so as to be freely pivotable. Further, a magnet 11 and a magnet yoke 12 are fixed to the fan 8 so as to face the annular stator 3 to constitute 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 furthermore, the protrusion generated by the ball rolling is removed to reduce the sleeve inner diameter to ± 2 μm or less. Sizing is performed to finish with precision.

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

  However, such a conventional motor has the following problems.

  In recent years, downsizing has progressed in electronic devices such as personal computers and home appliances, and accordingly, motors such as heat sink devices and cooling fan motors attached to electronic devices and the like have also been required to be smaller and thinner.

Due to the miniaturization and thinning of such an electric motor, the space of the bearing portion has become extremely small, and the wall thickness of the sleeve 6 has to be necessarily reduced. In addition, the press-fitting allowance between the sleeve 6 and the frame housing 1a is 20 μm or more in consideration of processing variation. 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. Had 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, so that the pumping force of the dynamic pressure generating groove 13 decreases, the whirling of the shaft 9 increases, the contact between the shaft 9 and the sleeve 6, This has caused the oil 14 to flow out, leading to a reduction in the reliability of the bearing.

  Also, the heat generation of electronic devices and the like is increasing due to high performance and miniaturization, and accordingly, electric motors used for heat sink devices and cooling fans attached to the electronic devices and the like are rotated at high speed to enhance the cooling effect. Is becoming necessary.

  On the other hand, the bearing oil 14 held by the surface tension in the gap between the shaft 9 and the sleeve 6 cannot withstand the centrifugal force due to the high-speed rotation, and the surplus oil flows out, and the surplus oil flows out. The required oil is also transmitted through the shaft 9 and the rotor 16 and flows out. Therefore, oil shortage of the bearing eventually occurs, so that the rotation speed decreases, the current value increases, and abnormal noise occurs, and further, the lock of the rotor 16 occurs, thereby deteriorating the reliability. Was.

  Therefore, an object of the present invention is to provide an electric motor capable of preventing deformation of the inner diameter of the sleeve.

  Another object of the present invention is to provide an electric motor that can prevent oil from flowing out of a bearing during rotation.

  Another object of the present invention is to provide a heat sink device using the electric motor and having high cooling efficiency.

  In order to solve this problem, an electric motor according to the present invention includes a frame having a cup-shaped frame housing, a stator attached to an outer peripheral portion of the frame housing, and a receiving seat formed in the frame housing. A sleeve fitted so as to be supported, a shaft rotatably fitted to the sleeve, and a rotor having a magnet arranged opposite to the stator; oil filled in a gap between the shaft and the sleeve; and a frame. A fixing ring inserted into the housing and pressing the sleeve toward the seat.

  As a result, the sleeve is fixed by being sandwiched between the receiving seat and the fixing ring, so that the stress applied in the radial direction of the sleeve is reduced, and the deformation of the sleeve inner diameter can be prevented.

  According to the first aspect of the present invention, one end is supported by a frame having a cup-shaped frame housing, a stator attached to an outer peripheral portion of the frame housing, and a receiving seat formed in the frame housing. The rotor fitted with a sleeve, a shaft rotatably fitted to the sleeve, and a magnet arranged opposite to the stator, oil filled in the gap between the shaft and the sleeve, Is a motor having a fixing ring inserted into the sleeve and pressing the sleeve toward the seat.Since the sleeve is fixed by being sandwiched between the seat and the fixing ring, the stress applied in the radial direction of the sleeve is reduced. In addition, there is an effect that deformation of the inner diameter of the sleeve can be prevented.

  According to a second aspect of the present invention, in the first aspect of the present invention, the sleeve is inserted into the frame housing with a gap of 0.1 mm or less, or is press-fitted with a interference of 5 μm or less. The motor has the effect of reducing the stress applied to the sleeve in the radial direction and preventing the inner diameter of the sleeve from being deformed.

According to a third aspect of the present invention, there is provided a frame having a cup-shaped frame housing, a stator mounted on an outer peripheral portion of the frame housing, a shaft mounted in the frame housing, and a cup-shaped rotor housing. A rotor provided with a magnet opposed to the stator, a sleeve mounted so that one end is supported by a receiving seat formed in the rotor housing, and rotatably fitted to the shaft; and a shaft and sleeve. And a fixing ring inserted into the rotor housing and pressed toward the receiving seat, such that the sleeve is fixed between the receiving seat and the fixing ring. The stress applied to the sleeve in the radial direction is reduced, and the deformation of the sleeve inner diameter can be prevented. It has the effect of kill.

  According to a fourth aspect of the present invention, in the third aspect, the sleeve is inserted into the rotor housing with a gap of 0.1 mm or less, or is press-fitted with a interference of 5 μm or less. The motor has a function of reducing the stress applied in the radial direction of the sleeve and preventing the inner diameter of the sleeve from being deformed.

  The invention according to claim 5 of the present invention is the electric motor according to any one of claims 1 to 4, wherein the end surface of the side of the fixing ring that contacts the sleeve has an uneven shape. Since the convex portion of the ring cuts into the sleeve to increase the fixing force of the sleeve, it has an effect of effectively preventing co-rotation between the sleeve and the shaft, increase in vibration, seizure of the bearing, and the like.

  The invention according to claim 6 of the present invention is the electric motor according to any one of claims 1 to 5, wherein the periphery of the insertion side of the fixing ring is an inwardly inclined electric motor. Has the effect that it can be inserted into the housing.

  According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, one of the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve is provided with a dynamic oil holding mechanism. This is an electric motor in which a pressure generating groove is formed, and has an operation of rotating the shaft smoothly.

  According to an eighth aspect of the present invention, there is provided a cooling fan motor including the electric motor according to any one of the first to seventh aspects, wherein a heat-generating body is mounted on a frame of the electric motor. This device is a device that conducts heat of the heating element directly to the frame of the electric motor, and the frame performs a heat radiating action, and the air flow generated by the fan efficiently hits the frame to enhance the heat radiating effect.

  According to a ninth aspect of the present invention, there is provided the heat sink device according to the eighth aspect, wherein plate-shaped or pin-shaped fins are provided on the frame, and the fins have a function of increasing heat radiation efficiency.

  According to a tenth aspect of the present invention, there is provided the heat sink device according to the ninth aspect, wherein one or more openings are provided in a side wall of the frame of the electric motor, and the position, size, and number of the openings are optimized. By doing so, it has the effect of directing the flow of air to other heating elements and smoothly exhausting high-temperature air.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. 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 a motor used in the heat sink device of FIG. 1, and FIG. 3 is a fixing ring mounted on the motor of FIG. FIG. 4 is a graph showing the amount of deformation of the inner diameter of the sleeve between the motor of FIG. 1 and a conventional motor.

  The motor according to the present embodiment, including the embodiments described below, is used for a heat sink device for cooling semiconductors. As shown in FIG. A drive circuit board 4 provided with a hall element and the like on a stator 3 around which a coil 2 is wound is provided around the frame housing 1a. Plate-shaped or pin-shaped fins 21 are erected in the concave portion of the frame 1, and a predetermined number of openings (not shown) through which air flows through the side walls are formed in predetermined directions in predetermined directions. 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 an outer peripheral portion of the frame housing 1a, and an insulating sheet 20 is provided 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 flow of air is fixed to a side wall of the frame 1.

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

  The periphery on the insertion side of the fixing ring 7 faces inward with an inclination of, for example, about 10 °, and is designed so that it can be easily pressed into the frame housing 1a.

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

  Further, a concave oil pool 8a for receiving the oil scattered from between the sleeve 6 and the shaft 9 during rotation is formed around the base of the shaft 9 extending from the fan 8. 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. 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 with respect to the fixing ring 7 is formed inside the fixing ring 7 on the outer periphery of the oil pool 8a.

  As shown in FIG. 2, on the inner peripheral surface of the sleeve 6, two dynamic pressure generating grooves 13 for smoothly rotating the shaft 9 are formed by ball rolling or the like. Sizing is performed to remove the protrusions and finish the sleeve inner diameter with a high accuracy of ± 2 μm or less. Oil 14 is lubricated into the dynamic pressure generating groove 13 as lubricating oil to form a radial bearing 17 while maintaining a bearing gap of 2 to 12 μm on one side with respect to the shaft 9. Note that 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 face of the shaft 9 on the side opposite to the fan 8 is finished to a spherical surface, and is in contact with the thruster 5 to form a thrust bearing 18.

  As a material of the sleeve 6, a copper alloy such as C3604 and 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. In addition, since the fan motor is often directly attached to a semiconductor and is close to a heat source, the oil 14 is made of a fluorinated synthetic oil that can withstand high temperatures, and is added to slightly improve extreme pressure properties. The agent has been added.

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

  If a gap of 0.1 mm or more is provided between the sleeve 6 and the frame housing 1a, a misalignment between the sleeve 6 and the stator 3 occurs, causing uneven rotation and the like. Further, when press-fitting with a margin of 5 μm or more is performed, the inner diameter of the sleeve 6 is deformed by 0.6 μm or more (see FIG. 9). Therefore, as described above, the sleeve 6 and the frame housing 1a are inserted with a gap of 0.1 mm or less, or a light press-fit of 5 mm or less is performed in consideration of processing variations. ing.

  An oil pool 8a whose volume is equal to or greater than the gap between the sleeve 6 and the shaft 9 is formed around the base 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, surplus oil scattered from the bearing during rotation is reliably pooled in the oil pool 8a. This prevents the necessary oil from flowing out.

  Even if the necessary oil becomes short due to evaporation or the like, the surplus oil is pooled in the oil pool 8a near the sleeve, so that the surplus oil is supplied to the bearing gap having a higher surface tension as needed. As a result, it is possible to prevent a shortage of oil in the bearing.

  Here, if 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 flowing in this gap decreases, and the oil 14 breaks through this gap. Conversely, if the thickness is 50 μm or less, the surface tension of the gap becomes strong, and a phenomenon of sucking up the oil 14 occurs, which causes a shortage of oil in the bearing and an increase in oil friction torque. For this reason, the rib 8b on the outer periphery of the oil pool 8a and the fixing ring 7 are arranged 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 and draws air along the axis 9 of the electric motor, flows along the air flow path formed by the fins 21, and is exhausted from the opening provided in the side wall of the frame 1. . At this time, the air flow takes heat from the frame 1 and the fins 21 to which the heat of the heating element is conducted, and performs a cooling action. The direction of the opening on the side wall should be adjusted according to the electronic device using the heat sink device in order to direct the air exhausted from the heat sink device to other heating elements and to smoothly exhaust the hot air from the electronic device. Open in one or more directions.

The shape of the fins 21 is not limited to a plate shape or a pin shape, but may be any shape having the same function and effect as a triangular shape, a wing shape, a spiral shape, a circular shape, a radial shape, and the like. When the size of the heat sink device is smaller than a predetermined size (40 mm square), the size of the motor is inevitably reduced, and as a result, the output of the motor is also reduced. Therefore, in the above case, the wind generated by the electric motor and the fan is reduced, and when the fins are erected, the amount of air discharged is reduced, which may worsen the heat radiation effect. As described above, when the size of the heat sink device is in the above range, it is preferable to improve the heat radiation effect by increasing the amount of air to be discharged without erecting the fin.

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

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

  By forming the fixing ring 7 into such a concave-convex shape, when the fixing ring 7 is press-fitted, the convex portion of the fixing ring 7 bites into the sleeve 6. Therefore, the fixing force of the sleeve 6 is further increased, and the slack of the sleeve 6 due to thermal shock, vibration, and dropping shock is eliminated, so that the sleeve 6 rotates together with the shaft 9, increases in vibration, and seizure of the bearing is effectively prevented. Will be done.

  The material of the fixing ring 7 is, for example, stainless steel such as SUS304 in consideration of spring properties and workability, and in consideration of making it harder than the sleeve 6 and easy to bite into the sleeve 6.

(Embodiment 3)
FIG. 6 is a 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 provided with a hall element and the like on a stator 3 around which a coil 2 is wound is provided around a cup-shaped frame housing 1a protrudingly formed in a concave portion of the frame 1. ing. The stator 3 is fixed to an outer peripheral portion of the frame housing 1a, and an insulating sheet 20 is provided between the drive circuit board 4 and the frame 1. A bell mouth 19 for fixing a smooth air flow is fixed to the outer periphery of the frame 1. Further, a shaft 9 is fixed in the frame housing 1a. The sleeve 6 is rotatably fitted on 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 forming a stator unit 15.

  A magnet 11 and a magnet yoke 12 are fixed to the fan 8 by bonding 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 so as to protrude from the fan 8. It is attached to.

  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 margin of 5 μm or less.

  A fixing ring 7 for pressing the fitted sleeve 6 against the receiving seat 8d is inserted into the rotor housing 8c, and constitutes a rotor 16 and is rotatably mounted via a bearing.

  The periphery on the insertion side of the fixing ring 7 faces inward with an inclination of, for example, about 10 °, and is designed so that it can be easily pressed into the frame housing 1a.

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

  The structure of the heat sink device and the structure of the electric motor used in the heat sink device, the type of the electric motor, the structure of the bearing, the oil, and the like are not limited to the contents of these embodiments, and various design changes can be made. Needless to say. Further, 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 fixed between the receiving seat and the fixing ring, the stress applied in the radial direction of the sleeve is reduced, and the deformation of the sleeve inner diameter can be prevented. An effective effect that can be obtained is obtained.

  As a result, a smooth operation can be performed, and an effective effect that a motor having high reliability and long life can be obtained can be obtained.

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

  In addition, by inclining the periphery of the fixing ring on the insertion side, an effective effect that the fixing ring can be easily inserted into the housing can be obtained.

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

Sectional drawing which shows the heat sink device by Embodiment 1 of this invention. Sectional drawing which shows the bearing part of the electric motor used for the heat sink device of FIG. Sectional drawing which shows the fixing ring attached to the electric motor of FIG. 1 is a graph showing the amount of deformation of the inner diameter of a sleeve between the motor of FIG. 1 and a conventional 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 device by Embodiment 3 of this invention. Sectional view showing a conventional heat sink device for cooling semiconductors. Sectional drawing which shows the bearing part of the electric motor used for the heat sink device of FIG. 7 is a graph showing a deformation state of a sleeve in the electric motor of FIG. 7.

Explanation of reference numerals

Reference Signs List 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 (10)

A frame with a frame housing;
A stator attached to an outer peripheral portion of the frame housing;
A sleeve fitted so that one end is supported by a receiving seat formed in the frame housing;
A shaft rotatably fitted into the sleeve, and a rotor having a magnet disposed to face the stator;
Oil filled in the gap between the shaft and the sleeve,
A fixing ring inserted into the frame housing and pressing the sleeve toward the receiving seat. 2. The electric motor according to claim 1, wherein the sleeve is inserted into the frame housing with a gap of 0.1 mm or less, or is press-fitted with a interference of 5 μm or less. A frame with a frame housing;
A stator attached to an outer peripheral portion of the frame housing;
A shaft mounted within the frame housing;
A rotor having a cup-shaped rotor housing and a magnet arranged to face the stator,
A sleeve which is mounted so that one end is supported by a receiving seat formed in the rotor housing and is rotatably fitted to the shaft;
Oil filled in the gap between the shaft and the sleeve,
A fixing ring inserted into the rotor housing and pressing the sleeve toward the receiving seat. 4. The electric motor according to claim 3, wherein the sleeve is inserted into the rotor housing with a gap of 0.1 mm or less, or is press-fitted with a interference of 5 μm or less. 5. The electric motor according to any one of claims 1 to 4, wherein an end surface of the fixing ring on a side contacting the sleeve has an uneven shape. The electric motor according to any one of claims 1 to 5, wherein the periphery of the insertion side of the fixing ring is inclined inward. The dynamic pressure generating groove for holding the oil is formed on one of the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. 7. The method according to claim 1, wherein: Electric motor. A cooling fan motor comprising the electric motor according to any one of claims 1 to 7, wherein a heating element is attachable to a frame of the electric motor. 9. The heat sink device according to claim 8, wherein plate-shaped or pin-shaped fins are erected on the frame. The heat sink device according to claim 9, wherein one or more openings are provided in a side wall of the frame of the electric motor.

Images