JP2003204655A - Spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor capable of preventing generation of lubricant leakage during high-speed rotation. <P>SOLUTION: The spindle motor is provided with a stator 23 comprising a motor base 5 fixed with a bearing 6 and a bearing holder 7, and a rotor 1 which fixes a spindle 4, retained rotatably by the bearing 6 and faces the stator 23. A lubricant circulating member 15, which sucks lubricant overflowing from the bearing 6 to the outside and circulates the lubricant to the bearing 6 through a capillary phenomenon, is established in a position which is inside a clearance between the inner periphery of the bearing holder 7 and the outer periphery of the spindle 4 and which is adjacent to at least either end of the bearing 6 in the direction of the spindle. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor, and more particularly to a laser beam printer (L) that rotates at an extremely high speed.
The present invention relates to a spindle motor for an aser beam printer (hereinafter referred to as LBP) and an optical disk driving spindle motor.

[0002]

2. Description of the Related Art The market for LBP which outputs paper information at high speed in order to manage a large amount of information generated in a company has been expanding in recent years. The role of the spindle motor used in the LBP is strongly required to be stable and ultra-high speed rotation due to the colorization. In other words, the bearing structure of the motor, which is essential for stable high-speed rotation, is becoming more important.

A conventional spindle motor will be described below with reference to FIGS. 5 and 6. FIG. 5 is a half sectional view of a conventional spindle motor. FIG. 6 is an enlarged view of a main part of the spindle motor shown in FIG. 5, and is a diagram for explaining generation of hydraulic pressure and outflow of the lubricating oil 26.

A conventional LBP driving spindle motor, which is a spindle motor, comprises a rotor 31 and a stator 33. In FIG. 5, a rotor 31 includes a bush 19 into which the spindle 4 is press-fitted, a rotor yoke 3 fixed to the bush 19, a mirror 11, a spring 12 fixing the mirror 11, and a ring-shaped drive magnet 14 fixed to the outer peripheral portion of the rotor yoke 3. It consists of

The rotor 31 has a ring-shaped drive magnet 14 fixed inside the outer peripheral portion of the rotor yoke 3. The inner peripheral portion of the drive magnet 14 is arranged to face the outer peripheral portion of the laminated core 8. In the rotor 31, the rotor yoke 3 is made of an iron-based magnetic material, and the spindle 4 made of a stainless steel material is press-fitted and fixed to the center thereof via a bushing 19.

The stator 33 includes a motor base 5, bearings 6,
The thrust plate 10, a resin thrust cover 9, an oil seal 17, a bearing holder 7, a laminated core 8, and a coil 2 wound around the laminated core 8. The bearing 6 is a slide bearing made of a sintered oil-impregnated metal such as copper or iron, and the flange portion 21 is screwed to the motor base 5 with a screw 18. A bearing holder 7 is provided on the outer peripheral portion of the cylinder of the bearing 6.
And the inner peripheral portion of the laminated core 8 is mounted on the outer peripheral portion of the bearing holder 7. The laminated core 8 is made of silicon steel plate,
The coil 2 is wound around the salient pole (not shown).

The spindle 4 is rotatably held by a sintered oil-impregnated bearing 6. The lower end of the spindle 4 constitutes a thrust bearing and a resin thrust plate 10 provided above the resin thrust cover 9. A ring-shaped oil seal 1 made of a silicon or rubber elastic material is provided between the outer periphery of the resin thrust cover 9 and the motor base 5.
7 is provided to prevent leakage of the lubricating oil 26. A rotor slip-off preventing screw 13 is attached to the motor base 5 outside the outer peripheral portion of the rotor yoke 3.

The mirror 11 is placed on the upper surface of the rotor 31, and is fixed to the bush 19 by the spring 12.
When a predetermined voltage is applied to the coil 2, the rotor 31 rotates and the hexagonal mirror 11 rotates. By rotating the mirror 11, in the actual LBP, as shown in FIG. 13, the laser beam 28 radiated to the side surface of the mirror 11 is reflected, and the photosensitive drum 29 is scanned so that printing on a sheet (not shown) becomes possible. Become.

[0009]

In recent years, an LBP driving spindle motor is required to have an ultra-high speed rotation and a long service life and high reliability at the same time in order to improve a printing speed. However, as will be described below, there is a problem in that the lubricating oil (oil) leaks from the end of the bearing to a greater extent as the rotation speed becomes higher, which greatly affects the life of the bearing. As shown in FIG. 6, the rotation of the spindle 4 causes an oil pressure 27 to be generated between the bearing 6 and the spindle 4, the lubricating oil 26 seeping out to the spindle surface and the bushing surface due to the surface tension, and the bearing holder 7 and the bush 19 due to the centrifugal force. It will flow out through the clearance portion 20 along the path indicated by the arrow. If the space between the lower end of the bushing 19 and the upper end of the bearing 6 is made narrower (lower) in order to reduce the height of the spindle motor, the outflow of the lubricating oil 26 will increase.

Therefore, the present invention has been made in view of the above problems, and in particular, the lubricating oil in the bearing 6 is sucked out by the capillary phenomenon from the lubricating oil flowing out from the bearing 6, and the bearing 6
By arranging the lubricating oil circulating member 15 that recirculates to the inside of the gap between the inner peripheral surface of the bearing holder 7 and the outer peripheral surface of the spindle 4 and at a position adjacent to at least one end of the bearing 6 in the spindle direction, An object of the present invention is to provide a spindle motor capable of suppressing the occurrence of lubricating oil leak in which the lubricating oil in the bearing 6 flows out.

[0011]

In order to solve the above problems, the present invention provides a spindle motor having the following configurations (1) to (3). (1) In a spindle motor including a stator having a motor base having a bearing and a bearing holder fixed thereto, and a rotor having a spindle fixed rotatably held by the bearing and facing the stator, the spindle motor is external to the bearing. A lubricating oil circulating member that sucks the lubricating oil flowing out to the bearing by a capillary phenomenon and circulates it back to the bearing, at least in the bearing in the gap between the inner peripheral surface of the bearing holder and the outer peripheral surface of the spindle and in the spindle direction. A spindle motor characterized by being arranged at a location adjacent to one end. (2) The spindle motor according to claim 1, wherein the lubricating oil circulating member is a donut-shaped thin plate having a plurality of stacked layers, or a porous sintered metal ring. (3) In the spindle motor according to claim 1 or 2, the difference C (clearance) between the inner diameter of the lubricating oil circulation member and the outer diameter D of the spindle is 1/100 ≤ C / D ≤ 1 Spindle motor characterized by being set to / 10.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the spindle motor of the present invention will be described below with reference to FIGS. 1 to 4 and FIGS. FIG. 1 is a half sectional view of an LBP driving spindle motor which is an embodiment of the spindle motor of the present invention, FIG. 2 is an enlarged view of a main part of the LBP driving spindle motor of FIG. 1, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a half sectional view of an example LBP driving spindle motor.
Is an enlarged view of the main part of the LBP driving spindle motor of FIG.
7 is a plan view and a cross-sectional view of a mirror used in an LBP driving spindle motor, FIG. 8 is a view showing a magnetic pole arrangement of a bias magnet of the LBP driving spindle motor, and FIG. 9 is another bias magnet of the LBP driving spindle motor. FIG. 10 is a diagram showing a magnetic pole arrangement, FIG. 10 is a diagram showing a state in which a shaft center of a bias magnet of an LBP driving spindle motor is deviated, and FIG. 11 is a motor life with respect to a clearance between an inner diameter of a donut-shaped thin plate and an outer diameter of the spindle. FIG. 12 is a view showing the life of the motor with respect to the clearance between the inner diameter of the ring made of porous sintered metal and the outer diameter of the spindle, and FIG. 13 is a view for explaining the main part of the LBP equipped with the spindle motor for driving the LBP. FIG.

In FIG. 1, a rotor 1 has a ring-shaped drive magnet 14 fixed to the inside of an outer peripheral portion of a rotor yoke 3 made of an iron-based magnetic material with an adhesive, and an inner peripheral portion of which is provided with a brass bush (bushing) 19 and a spindle. The (shaft) 4 is press-fitted and fixed. The bushing 19 has a bearing end portion made of resin (for example, P to prevent leakage of lubricating oil from the sintered oil-impregnated bearing 6).
An OM oil deflector 22 is press-fitted onto the spindle 4 on the end face of the bush 19.

A bush (19) on the upper surface of the rotor yoke (3) is mounted with a mirror (polygon mirror) 11 shown in FIG. 7 which is formed by processing an aluminum material into a hexagon, and the mirror (11) is held by the bush (19) by a spring (12).
The spindle 4 is press-fitted and fixed to a bushing 19 and is rotatably held by a bearing 6. That is, the spindle 4
It is rotatably held in a bearing 6 fixed to the motor base 5.

In order to prevent the spindle 4 from coming off from the bearing 6, a stopper (removal preventing screw) 13 is provided outside the motor base 5. As the stopper 13, a screw having a large brim is used, and only the tip of the screw is fastened to the motor base 5.

On the other hand, the stator 23 comprises a bearing 6, a bearing holder 7, a resin thrust cover 9, a resin thrust plate 10, a motor base 5, and a core 8 around which the coil 2 is wound. The bearing 6 and the bearing holder 7 are the motor base 5
It is fixed on. The bearing 6 is a sintered oil-impregnated bearing such as copper or iron, and a resin bearing holder 7 is press-fitted into the outer peripheral portion of the bearing 6, and a coil 2 is wound around the outer peripheral portion of the bearing holder 7 to form a laminated core made of a silicon steel plate. The inner peripheral portion of 8 is fixed.

At the lower end of the spindle 4, a resin-made thrust plate 10 provided above the resin-made thrust cover 9 is provided.
The thrust bearing is composed of. A ring-shaped oil seal 17 made of a silicon or rubber elastic material is provided between the outer periphery of the resin thrust cover 9 and the motor base 5.

A bias magnet 16 is adhesively fixed to the upper surface of the laminated core 8 on the outer periphery of the bearing holder (core bushing) 7. The bias magnet 16 is magnetized only in a substantially half portion on the circumference, as shown in the drawing showing the magnetic poles of the bias magnet in FIG.

Therefore, the inner peripheral end portion 24 of the rotor yoke 3 facing the bias magnet 16 is attracted by the magnetic force of the magnetized side portion of the bias magnet 16. Since the bias magnet 16 is composed of N and S magnetic pole portions and non-magnetized portions, the rotor 1 causes the spindle 4 to move toward the bearing 6 in one direction by attracting only one side.

The clearance between the spindle 4 and the bearing 6 is reduced by this backlash to prevent the occurrence of vibration due to oil hoar. Oil hoar is an unstable motion of the spindle that occurs during high speed rotation. Since the mirror 11 is fixed to the spindle (shaft) 4, when an oil hoar is generated, unstable movement of the mirror 11 occurs, which causes a tilt.

The magnetized form of the bias magnet 16 may be as shown in FIG. 9 showing the magnetic poles of the bias magnet, and in this case as well, the attraction of the upper side surface having a large number of magnetic poles becomes strong. Further, as shown in FIG. 10, the center of the bias magnet 16 magnetized to the N and S poles around the entire circumference and the spindle 4 are arranged.
There is also a method in which the center of the rotor is shifted and the rotor 1 is rattled by the difference between the right and left attraction forces.

Next, a method for preventing leakage of lubricating oil will be described with reference to FIG. Lubricating oil 2 for bearing 6
In order to hold 6, the lubricating oil is provided in the space between the inner peripheral surface of the bearing holder 7 and the outer peripheral surface of the spindle 4, and in the axial direction (longitudinal direction) of the spindle 4 adjacent to the end of the bearing 6. The circulation member 15 is arranged. In this embodiment, the lubricating oil circulation members 15 are arranged at both ends of the bearing 6.
Even if the lubricating oil circulating member 15 is arranged at one end portion of the bearing 6 (only the upper end portion in FIG. 1), the same operational effect as the structure in which the lubricating oil circulating member 15 is arranged at both end portions of the bearing 6 respectively. Can be obtained. The bearing 6 is a sintered oil-impregnated bearing, and the rotor 1
Lubricating oil 26 springs out from the bearing 6 due to the high speed rotation of
The lubricating oil 26 flows out to the upper and lower ends of the bearing 6 due to surface tension. The clearance G between the inner circumference of the bearing 6 and the outer circumference of the spindle 4 is 0.003 mm.

Here, the inner diameter of the lubricating oil circulating member 15 for preventing the lubricating oil 26 from flowing out is larger than the inner diameter of the bearing 6, and the clearance C between the inner diameter of the lubricating oil circulating member 15 and the spindle outer diameter D is the bearing holder. 7 Inner diameter and lubricating oil circulation member 15
It is set to be larger than the clearance formed by the outer diameter of the.

By setting in this way, the lubricating oil 2
6 lubricates the sliding surfaces of the spindle 4 and the bearing 6, and flows out along the clearance between the inner peripheral portion of the lubricating oil circulating member 15 and the outer peripheral portion of the spindle 4 due to the hydraulic pressure 27 and the surface tension, but due to the capillary phenomenon. It is absorbed by the overlapping gap of the lubricating oil circulating member 15, moves to the outer periphery of the member, returns to the sliding surface of the bearing 6, and circulates so as to contribute to the lubrication of the spindle 4 and the bearing 6 again.

Next, the case where the lubricating oil circulating member 15 is a donut-shaped thin plate will be described below. In order to retain the lubricating oil 26 of the bearing 6 of FIG. 2, the upper and lower ends of the bearing 6 each have 5 to 6 donut shapes (the donut shape is concentric or substantially concentric with an outer diameter and an inner diameter, and has a thickness of approximately It refers to a uniform ring shape.) Thin plates are stacked. In this embodiment, a stainless thin plate such as SUS301 is pressed to have an outer diameter of 5.96 mm, an inner diameter of 3.24 mm, and a thickness of 0.3.
I use 5 mm ones on top of each other.

In addition to FIGS. 3 and 4, the lubricating oil circulating member 1 is used instead of the flat washers (thin plates) of FIG.
The case where a porous sintered metal ring 25 is provided as No. 5 will be described below. The inner circumference of the porous sintered metal ring 25 is larger than the inner circumference of the bearing 6, and the outer peripheral surface of the porous sintered metal ring 25 is held on the inner peripheral surface of the bearing holder 7. The ring 25 made of porous sintered metal
May or may not be impregnated with lubricating oil. However, if impregnated, the amount of lubricating oil retained in the bearing increases, so the life improving effect is exerted, and it is more preferable. is there.

Next, together with FIGS. 2 and 11, the inner diameter of the donut-shaped thin plate 15 which is a lubricating oil circulation member and the spindle 4
The relationship between the clearance C with respect to the outer diameter D and the reliability life (time (Hr)) of the motor will be described.

The data of FIG. 11 is obtained by using a donut-shaped thin plate as the lubricating oil circulating member, the outer diameter D of the spindle is 3 mm, and the clearance C is obtained as the difference (clearance) between the inner diameter of the donut-shaped thin plate and the outer diameter D of the spindle. It is a thing.

In FIG. 11, the rotational speeds are 5000 and 2000.
The relationship between the clearance and the life at 0,40,000 (1 / min) is shown. The graph of FIG. 11 shows that the effect of the clearance on the life has a greater effect as the rotational speed increases.

When the clearance C is less than 0.03 (= D / 100) at 40,000 (1 / min), the oil pressure of the lubricating oil circulating member becomes high, and the lubricating oil flows out along the spindle. , The circulation function is not fully exerted, the life shortens rapidly, and the life is 3000 (Hr)
Less than. Similarly, the clearance C is 0.3 (=
If it is larger than D / 10), the lubricating oil suction force due to the capillary phenomenon becomes insufficient, so the circulation function is not fully exerted,
The life is rapidly reduced, and the life is shorter than 3000 (Hr). Generally, the life required for an LBP motor is 300
It is 0 hours, and it can be seen that the required life required for the LBP motor or the like can be achieved by setting the clearance C to 1/100 ≦ C / D ≦ 1/10.

Therefore, when the difference (clearance) C between the inner diameter of the doughnut-shaped thin plate 15 and the outer diameter D of the spindle is 1/100 or more and 1/10 or less of the outer diameter of the spindle, it follows the outer diameter of the spindle 4. The doughnut-shaped thin plate 15 recirculates the lubricating oil 26 that has leaked out to the bearing 6 and is effectively used without leaking to the outside.

Next, a case where the lubricating oil circulating member is a porous sintered metal ring will be described with reference to FIGS. Similar to FIG. 11, the data of FIG. 12 shows the clearance and the life with respect to the rotation speed. The lubricating circulation member used was a ring made of porous sintered metal, and the outer diameter D of the spindle was 3 mm.

As can be seen from the data in FIG. 12, the inner diameter of the ring 25 made of porous sintered metal and the outer diameter D of the spindle.
By setting the difference (clearance) C between and 1/100 ≤ C / D ≤ 1/10, the reliability life of the motor can be significantly improved. By setting such a relationship, a high-speed, long-term, highly reliable bearing can be secured.

Although the above description has specifically described application of the spindle motor according to the present invention to a spindle motor for driving a laser beam printer that rotates at an extremely high speed, the present invention is not limited to this example, and the same applies. Also for the optical disk drive spindle motor having the configuration of
It goes without saying that the same can be applied.

[0035]

As described above, according to the present invention, the lubricating oil circulating member sucks the lubricating oil flowing out from the bearing to the outside by the capillary phenomenon into the gap where the donut-shaped thin plates are stacked. Since it can flow back into the bearing through the gap between the outer peripheral part and the inner peripheral part of the bearing holder, it is possible to reliably prevent the occurrence of lubricating oil leak in which the lubricating oil in the bearing flows to the outside. Therefore, it is possible to provide a spindle motor which does not cause seizure between the bearing and the spindle and has a long life and high reliability.
Further, according to the present invention, by disposing a donut-shaped thin plate (flat washer) as the lubricating oil circulation member, the lubricating oil flowing out from the inside of the bearing to the outside of the bearing is held in the gap of the flat washer that overlaps with the sliding bearing. Since the occurrence of lubricating oil leakage can be reliably suppressed even at high speed rotation, it is possible to provide a spindle motor with long life and high reliability. Further, according to the present invention, by arranging a porous sintered metal ring as the lubricating oil circulation member, the porous sintered metal ring in which the lubricating oil flowing from the inside of the bearing to the outside of the bearing is overlapped with the sliding bearing. Since it is held by, the occurrence of lubricating oil leakage can be surely suppressed even when the spindle rotates at a high speed, so that it is possible to provide a spindle motor having a long life and high reliability.

[Brief description of drawings]

FIG. 1 is a half sectional view of a spindle motor for driving an LBP, which is an embodiment of the spindle motor of the present invention.

FIG. 2 is an enlarged view of a main part of the LBP driving spindle motor of FIG.

FIG. 3 is a half sectional view of a spindle motor for driving an LBP, which is another embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of the LBP driving spindle motor of FIG.

FIG. 5 is a half sectional view of a conventional spindle motor.

FIG. 6 is an enlarged view of a main part of the spindle motor shown in FIG.

FIG. 7 is a plan view and a sectional view of a mirror used in an LBP driving spindle motor.

FIG. 8 is a diagram showing a magnetic pole arrangement of a bias magnet of an LBP driving spindle motor.

FIG. 9 is a diagram showing another magnetic pole arrangement of the bias magnet of the LBP driving spindle motor.

FIG. 10 is a diagram showing a state in which the axial center of the bias magnet of the LBP driving spindle motor is deviated.

FIG. 11 is a diagram showing the life of the motor with respect to the clearance between the inner diameter of the donut-shaped thin plate and the outer diameter of the spindle.

FIG. 12 is a diagram showing the life of the motor with respect to the clearance between the inner diameter of the ring made of porous sintered metal and the outer diameter of the spindle.

FIG. 13 is a diagram for explaining a main part of an LBP equipped with an LBP driving spindle motor.

[Explanation of symbols]

1, 31 rotor 2 coil 3 rotor yoke 4 spindle (shaft, shaft) 5 motor base 6 bearing 7 bearing holder (core bushing) 8 laminated core 9 resin thrust cover 10 (resin) thrust plate 11 hexagonal mirror (polygon mirror) ) 12 Spring 13 Stopper (prevention screw) 14 Drive magnet 15 Lubricating oil circulating member (thin plate like donut) 16 Bias magnet 17 (Ring) Oil seal 18 Screw 19 Bushing (bushing) 20 Clearance 21 Collar 22 of bearing 6 Oil deflectors 23, 33 Stator 24 Inner peripheral end 25 of rotor yoke 3 Porous sintered metal ring 26 Lubricating oil (oil) 27 Oil pressure 28 Laser light 29 Photosensitive drum C Luminous oil circulating member 15 inner diameter and spindle outer diameter Clearance with D Bundle forms a clearance between the inner circumference and the outer circumference of the spindle 4 having an outer diameter G bearing 6 (the shaft)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C362 BA10                 5H605 BB05 BB10 BB14 BB19 CC04                       DD03 DD09 EB02 EB06 EB13                       EB21 EB28                 5H607 AA05 BB01 BB07 BB09 BB14                       BB17 BB25 CC09 DD03 DD16                       GG07 GG09 GG25 KK03 KK10

Claims (3)

[Claims] 1. A spindle motor comprising: a stator having a motor base having a bearing and a bearing holder fixed thereto; and a rotor having a spindle fixed rotatably supported by the bearing and facing the stator. A lubricating oil circulating member for sucking the lubricating oil flowing out from the outside to recirculate to the bearing by a capillary phenomenon, in the bearing in the gap between the inner peripheral surface of the bearing holder and the outer peripheral surface of the spindle and in the spindle direction. A spindle motor arranged at a position adjacent to at least one end of the spindle motor. 2. The spindle motor according to claim 1, wherein the lubricating oil circulating member is a plurality of donut-shaped thin plates stacked together.
Alternatively, the spindle motor is a ring made of porous sintered metal. 3. The spindle motor according to claim 1, wherein the difference C (clearance) between the inner diameter of the lubricating oil circulation member and the outer diameter D of the spindle is 1/100 ≦ C / D. A spindle motor characterized in that ≤ 1/10.