JP4333488B2 - Brushless motor - Google Patents

Description

  The present invention mainly relates to a brushless motor (hereinafter abbreviated as a motor) used for driving a disk in an apparatus for recording and reproducing information such as CD-ROM (R / RW) and DVD ± (R / RW). In particular, the present invention relates to a motor bearing device.

  In recent years, a motor that rotates and drives a disk that records and reproduces information such as CD-ROM (R / RW) and DVD ± (R / RW) is oil-impregnated from a porous metal due to the demand for low cost. Metal is used as a general bearing means (see the prior art in Patent Document 1).

  FIG. 2 is a sectional view showing the structure of a conventional motor. In FIG. 2, 21 is an output shaft for transmitting rotation, 22 is an oil-impregnated metal, 23 is a housing for holding the oil-impregnated metal, 24 is a rotor, 25 is a stator, and 26 is a bracket made of a printed circuit board. The motor obtains a rotational force by a magnetic force generated sequentially between the rotor 24 and the stator 25, and the output shaft 21 fixed at the center of the rotor 24 is fixed to the oil-impregnated metal 22 and the bracket 26. It is supported rotatably by a bearing device composed of a housing 23 and transmits rotation with high accuracy to the outside.

  However, along with the increase in the speed of recording and reproducing media equipment such as CD-ROM (R / RW) and DVD ± (R / RW), the margin of long-term reliability of the bearing means is reduced, and the bearing means The necessity of the oil retaining structure of the oil-impregnated metal that constitutes the material and the countermeasures against scattering of the oil contained in the oil-impregnated metal have become important issues.

  That is, in the conventional configuration as described above, since the outer periphery of the oil-impregnated metal is hermetically sealed by the housing, the pressure applied to the end face of the oil-impregnated metal due to the pressure generated at the contact portion between the output shaft and the oil-impregnated metal when the output shaft rotates. Increases, and the oil blows out to the oil-impregnated metal end face, and particularly adheres to the inner top face on the top face side of the rotor. Furthermore, the oil adhering to the rotor diffuses in the radial direction on the inner top surface of the rotor due to centrifugal force and does not return to the oil-impregnated metal, so the oil retained in the oil-impregnated metal decreases and normal lubrication does not work. There was a problem that accurate rotation transmission was not performed.

  Therefore, the applicant provides a motor bearing device that can reduce the amount of oil blown to the oil-impregnated metal end face while maintaining cost reduction and can maintain accurate rotation transmission for a long time, and an excellent motor equipped with this device. For this purpose, the pressure on the end face of the oil-impregnated metal is reduced by providing a portion that does not seal the outer periphery of the oil-impregnated metal on the top surface side of the rotor of the press-fit portion of the oil-impregnated metal and housing. Has been proposed (see Patent Document 1).

  The configuration of this motor is shown in FIG. In FIG. 3, 31 is an output shaft, 32 is an oil-impregnated metal, 35 is a bracket, 33 is a housing, and 34 is a rotor. The housing 33 is formed integrally with the bracket 35, and the dimension of the oil-impregnated metal holding portion 36 is set to 1/2 to 4/5 of the entire length of the oil-impregnated metal 32 on the top surface side of the rotor 34. The outer periphery of the oil-impregnated metal 32 on the 34 side is opened. With this configuration, oil can be prevented from blowing out to the end face of the oil-impregnated metal, and the bracket and the housing are integrally formed, so that the number of motor components can be reduced.

  However, along with the drastic increase in speed of equipment such as CD-ROM (R / RW) and DVD ± (R / RW), the radial and bearing end face pressures inside the bearing due to disc imbalance are higher than expected. It became a thing. In the configuration of the second conventional example, there has been a problem that the oil flows out from the outer periphery of the oil-impregnated metal released by this pressure and the bearing end surface, making it difficult to meet the demand for longer life.

Therefore, the applicant attaches the cylindrical cover to the open portion of the oil-impregnated metal outer periphery with a gap between the end surface of the oil-impregnated metal and the outer periphery, so that the oil extruded from the end surface of the oil-impregnated metal is scattered during rotation. Even so, the cover becomes a wall for preventing oil scattering, and further, the oil of the oil-impregnated metal scattered in the cylindrical portion by the gap between the outer periphery of the oil-impregnated metal and the cylindrical portion of the cover passes through the gap. An oil recovery structure for returning to oil-impregnated metal has been proposed (see Patent Document 2).

FIG. 4 shows the configuration of the motor of the third conventional example. In FIG. 4, 41 is an output shaft, 42 is an oil-impregnated metal, 43 is a rotor, and 46 is a bracket in which a burring portion 45 and a motor mounting base portion 44 are integrally formed. The oil-impregnated metal 42 is fixed to the inner peripheral portion of the burring portion 45 of the bracket 46 in a state where a part of the outer periphery is released, and the stator core 47 is fixed to the outer peripheral portion of the burring portion 45. A cylindrical metal holder 52 (cover) comprising a cylindrical portion 50 having a gap from the end surface and outer periphery of the oil-impregnated metal 42 and an end surface portion 51 extending from the one end portion of the cylindrical portion toward the inner diameter side. The end face of the burring part 45 of the bracket 46 and the other end face of the cylindrical part 50 of the metal holder 52 are press-fitted and fixed to the inner peripheral part of the stator core 47.
JP-A-9-294350 (page 2-3, FIG. 3, FIG. 4) JP 2002-262540 A (Page 4-5, FIG. 1)

  However, in the above-described conventional configuration, it is difficult to finish each end face of the metal holder and the burring portion of the bracket to an ideal plane, so that a minute gap is generated on the butt face of both end faces. Is inevitable. Further, since the metal holder is fixed to the inner diameter of the stator core formed by the laminated iron core, there is a possibility that oil flows out from the gap between the butted surfaces into the gap between the iron cores of the laminated core due to capillary action. For this reason, there has been a problem that during operation of the motor, oil of the oil-impregnated metal gradually flows out from this gap, and it is difficult to maintain sufficient reliability for a long time.

  The present invention solves such a conventional problem, and a motor bearing device capable of maintaining accurate rotation transmission for a long time even at high speed rotation, and an excellent motor equipped with this device at low cost. The purpose is to provide.

In order to solve the above problems, the present invention provides an annular elastic body between the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder, and presses the elastic body. Then, the brushless motor is characterized in that the oil outflow due to the capillary phenomenon from the gap between the butted surfaces of the both end faces to the gap between the iron cores of the stator core is suppressed .

  According to the invention described in claim 1, since the compressed elastic body is interposed between the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder, it becomes a higher sealing structure, The oil-impregnated metal has an advantageous effect that oil leakage from the gap between the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder and the abutting surface can be prevented.

  Further, according to the invention described in claim 2, a motor with high reliability and long life can be obtained.

According to a first aspect of the present invention, there is provided a bracket made of a magnetic material in which a burring portion constituting a bearing housing at a central portion and a mounting base portion for mounting a motor are integrated, An oil-impregnated metal in which a part of its entire length is press-fitted and fixed inside the burring processing portion of the bracket, and is placed outside the burring processing portion of the bracket, and a copper wire through an insulator on the stator core A frame having a shaft fixed at the center, and a cylindrical rotor magnet fixed to the inner periphery of the frame and multipolarly magnetized in the circumferential direction. A metal holder comprising a cylindrical portion and an end surface portion extending from the one end portion of the cylindrical portion toward the inner diameter side, the end surface portion being spaced apart in the axial direction from the top surface of the frame. The outer circumference of the oil-impregnated metal and the metal holder A gap is provided between the cylindrical portion and the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder are pressed into and fixed to the inner diameter portion of the stator core. In the brushless motor, an annular elastic body is disposed between the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder, and presses the elastic body. The brushless motor is characterized in that the both end surfaces are butted, and a compressed elastic body is interposed between the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder. , Oil leakage from oil-impregnated metal from the gap between the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder and the abutting surface can be prevented. Having an iodine.

  The invention according to claim 2 is an elastic body made of petroleum synthetic rubber-based nitrile rubber. By using an elastic body excellent in heat resistance, oil resistance, and wear resistance, the reliability is high and the life is shortened. It has the effect that a long motor can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
In FIG. 1, reference numeral 1 denotes a shaft for transmitting rotation. Reference numeral 2 denotes a frame, in which a ring-shaped rotor magnet 3 magnetized in the circumferential direction is press-fitted or bonded and fixed to the inner periphery of the frame 2. Then, burring is applied to the center of the frame 2 and the shaft 1 is directly press-fitted. In this way, the rotor 10 is composed of the shaft 1, the frame 2, and the rotor magnet 3.

  The bracket 4 is made of a magnetic material and is formed by a pressing method, and has a stepped burring portion 11 in a substantially central portion. The burring portion 11 functions as a bearing housing for housing the bearing means. In the bracket 4, a burring portion 11 constituting a bearing housing and an attachment base portion 12 for attaching a motor are integrally formed. In this way, since the burring portion 11 and the mounting base portion 12 are integrally formed, the squareness of the mounting base portion 12 with respect to the burring portion 11 is formed with high accuracy. It becomes easy.

  An oil-impregnated metal 5 is press-fitted and fixed inside the burring portion 11 of the bracket 4 in order to rotatably support the shaft 1.

  On the other hand, a stator winding assembly in which a stator coil 6 is wound around a stator core 8 via a resin insulator is press-fitted and fixed outside the burring portion 11 of the bracket 4.

  Further, a printed circuit board 7 on which at least a part of a circuit for driving and controlling the motor is mounted is adhesively fixed to the mounting base portion 12 with a double-sided tape (not shown). The winding end of the stator coil 6 of the stator winding assembly is wired on the printed circuit board 7 to form a stator 9.

  On the inner diameter side of the stator core 8, there are a cylindrical portion 15 and an end surface portion 13 extending from the one end portion of the cylindrical portion 15 to the inner diameter side at a position having a clearance from the end surface and outer periphery of the oil-impregnated metal 5. In the cylindrical metal holder 14 to be formed, the cylindrical portion 15 of the metal holder 14 is press-fitted and fixed at a position where the end surface portion 13 has a gap in the axial direction from the top surface of the frame 2.

  The above configuration is the same as that of the third conventional example. In the first embodiment, an annular elastic body 18 is disposed between the end surface of the burring portion 11 of the bracket 4 and the other end surface 16 of the cylindrical portion 15 of the metal holder 14. The configuration in which the elastic body is pressed and the both end faces are brought into contact with each other is the difference from the third conventional example.

  Since the compressed elastic body 18 is interposed between the end surface 17 of the burring portion 11 of the bracket 4 and the other end surface 16 of the cylindrical portion 15 of the metal holder 14 with the above configuration, a higher sealing structure is obtained. Oil in the oil-impregnated metal 5 can be prevented from leaking from the gap between the abutting surfaces of the end surface 17 of the burring portion 11 of the bracket 4 and the other end surface 16 of the cylindrical portion 15 of the metal holder 14.

(Embodiment 2)
In FIG. 1, the elastic body 18 is made of petroleum synthetic rubber-based nitrile rubber manufactured by Marutomo Rubber Mfg. Co., Ltd.

  According to this embodiment, a motor with high reliability and a long life can be obtained.

  In the above description, an example in which the elastic body is made of a silicon-based synthetic rubber has been described. However, other petroleum synthetic rubber-based nitrile rubbers can be similarly implemented.

  The brushless motor having the bearing structure of the present invention is useful as a brushless motor used for driving a disk in an apparatus for recording and reproducing information such as CD-ROM (R / RW) and DVD ± (R / RW). It is.

Sectional drawing which shows the structure of the motor by Embodiment 1 and Embodiment 2 of this invention Sectional drawing which shows the structure of the 1st conventional motor Sectional drawing which shows the structure of the 2nd conventional motor Sectional view showing the structure of a third conventional motor

1, 21, 31, 41 Shaft (output shaft)
2 Frame 3 Rotor magnet 4, 26, 35, 46 Bracket 5, 22, 32, 42 Oil-impregnated metal 6 Stator coil 7 Printed circuit board 8, 47 Stator core 9 Stator 10, 24, 34, 43 Rotor 11, 33, 45 Burring processing part (housing)
12, 44 Mounting base part 13, 51 End face part 14, 52 Metal holder (cover)
DESCRIPTION OF SYMBOLS 15, 50 Cylindrical part 16 The other end surface of a cylindrical part 17 End surface of a burring process part 18 Elastic body 20 Press-fit inner diameter part 23 Bearing housing 25 Stator

Claims (2)

A bracket made of a magnetic material in which a burring portion constituting a bearing housing and a mounting base portion for motor mounting are integrated in a central portion, and the inner side of the burring portion of the bracket. An oil-impregnated metal whose part of the entire length is press-fitted and fixed, an armature that is disposed outside the burring portion of the bracket, and in which a copper wire is wound around a stator core made of a laminated iron core via an insulator, And a cylindrical rotor magnet fixed to the inner periphery of the frame and multipolarly magnetized in the circumferential direction. A metal holder comprising an end surface portion extending from the one end portion to the inner diameter side is opposed to the end surface portion with a gap in the axial direction from the top surface of the frame, and the outer periphery of the oil-impregnated metal And the cylindrical part of the metal holder In a brushless motor that is press-fitted and fixed to the inner diameter portion of the stator core so that the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder are abutted with each other. An annular elastic body is disposed between the end surface of the burring portion of the bracket and the other end surface of the cylindrical portion of the metal holder, and the elastic body is pressed to butt the both end surfaces. A brushless motor characterized by suppressing oil outflow due to capillary action from a gap between the surfaces to a gap between each iron core of the stator core . 2. The brushless motor according to claim 1, wherein the elastic body is a petroleum synthetic rubber-based nitrile rubber.

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