JPS62141675A - Spindle motor - Google Patents

Abstract

PURPOSE:To obtain a device small in size, thin in thickness and an intelligent circuit in a spindle motor of a magnetic disk device by placing a rotor magnet in the inner peripheral side of a stator coil. CONSTITUTION:A rotor magnet 7 divided into plural poles and magnetized is fixed on the outer peripheral part of a rotor yoke 6 fixed to a shaft 1 and a stator core 8 is installed on the outer peripheral side. The diameter of the rotaton of the rotor yoke 6 becomes as wall as about a half, and interference and contact between the stator coil 9 and rotor yoke 6 do not occur, and accordingly, the mounting space of a circuit substrate is increased, and the circuit can be made intelligent. Further, as the area for heat radiation of the stator coil and stator core is almost doubled, possibility of burning when excess current is applied is eliminated, and reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spindle motor structure for a magnetic disk device.

[Summary of the invention]

The present invention is a spindle motor for a magnetic disk device, in which a rotor magnet is disposed on the inner circumferential side of a stator core around which a stator coil is wound, thereby making the spindle motor smaller and thinner and increasing the mounting density of the magnetic disk device. It is.

[Prior art]

As shown in FIG. 3, in the spindle motor of a conventional magnetic disk device, a hub 2 is fixed to one end of a shaft 1, and a plurality of magnetic disks 3 are attached to the hub 2 by a disk clamp plate 5 via a disk spacer 4. A cup-shaped rotor yoke 6 is fixed to the other end of the shaft 1, a ring-shaped rotor magnet 7 is fixed to the inner circumference of the rotor yoke 6, and a stator core 8 is arranged on the inner circumference side of the rotor magnet 7 with a gap in between. A stator coil 9 is wound around the stator core 8, the shaft 1 is supported by a bearing 10, the bearing 10 and the stator core 8 are fixed to a housing 12, and a seal 11 is used to keep the atmosphere in which the magnetic disk 3 exists clean. It is sealed and fixed as a spindle motor to a base frame 13 of a magnetic disk device by a part of the housing 12, the inside of the base frame 13 is sealed with a cover 14, and furthermore, the circuit of the magnetic disk device is installed under the rotor yoke 6 of the spindle motor. A circuit board 15 on which components are mounted is provided. Rotor magnet 7
is divided into multiple poles in the radial direction, and the stator core 8 has multiple slots and multiple phase stator coils 9.
The rotational position of the rotor magnet 7 is detected by a magnetic sensor, and the stator coil 9 is sequentially energized to generate two rotations, causing the rotor yoke 6, shaft 1, magnetic disk 3, etc. to rotate.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, since the height of the rotor yoke in the shaft direction is large, circuit components cannot be mounted on the lower part of the rotor yoke on the circuit board of the magnetic disk device.
It is difficult to increase the mounting area of a circuit board with the same height of a conventional magnetic disk drive, and as magnetic disk drives become smaller, the area of the entire circuit board that is difficult to mount on a circuit board outside the rotating diameter of the rotor yoke is difficult to increase. The proportion of this will increase. Furthermore, since the stator coil is surrounded by the rotor yoke, heat dissipation from the stator coil is poor and there is a risk of burnout of the coil when excessive current is applied, reducing the reliability of the spindle motor.

In particular, to improve the mounting density of magnetic disk devices, in-hub motors with rotor magnets etc. installed inside the hub have been used for a long time. Set the height to half-hide (41
In the case of a thin magnetic disk with an inner diameter of 40 mm or less, there are many problems such as bearing rigidity, coil heat dissipation, and magnetic shielding as well as generated torque. It is difficult to apply it to devices.

The present invention is intended to solve these problems, and its purpose is to make the spindle motor smaller and thinner, increase the mounting area of the circuit board of the magnetic disk drive, make the device smaller and thinner, and make the circuit more intelligent. It is in a place that makes it possible.

Still another object is to obtain a highly reliable spindle motor for a magnetic disk device, which improves heat dissipation of the stator coil of the spindle motor, has sufficiently large bearing rigidity, and generates sufficient torque. Another purpose is to provide a half-hide magnetic disk device in which three or four small magnetic disks with an inner diameter of about 2 to 5 mm are mounted, and the circuit board has enough space to mount a disk controller circuit. The goal is to obtain a spindle motor that enables intelligent circuits.

[Failure to solve the problem]

The spindle motor of the present invention is a spindle motor for a magnetic disk device in which a magnetic disk serving as a magnetic recording medium has an inner diameter of 40 mm or less and a plurality of the magnetic disks are mounted and rotated to perform magnetic recording and reproducing. A magnetized rotor magnet is arranged on the inner circumferential side of a stator coil which is divided into multiple phases and wound, and the stator coil is wound around a stator core having a plurality of slots on the inner circumferential side. . .

[Effect]

According to the above configuration of the present invention, the rotational diameter of the rotor yoke can be made smaller than the inner diameter of the stator core, the stator coil and rotor yoke do not interfere with each other, the circuit mounting space between the rotor yoke and the circuit board is increased, and the stator core The heat dissipation area also increases.

〔Example〕

FIG. 1 is a sectional view of a main part of a spindle motor according to an embodiment of the present invention, and is a Q sectional view of the spindle motor installed in a magnetic disk drive. A disk 3 is attached to the hub 2 by a disk clamp plate 5 via a disk nupacer 4, and a rotor yoke 6 is fixed to the other end of the shaft 1, and the outer circumferential portion of the rotor yoke 6 is magnetized in a plurality of poles in the radial direction. A rotor magnet 7 in the form of a ring shape or a collection of arcuate magnets in a ring shape is fixed, and a stator core 8 around which a stator coil 90 is wound is disposed on the outer circumferential side of the rotor magnet 7 with a gap in between, and supports the shaft 1. The stator core 8 is fixed to a housing 12 together with a bearing 10 for sealing and a seal 11 for dustproof sealing, and the housing 12 is fixed to a base frame 15 of the magnetic disk drive. A circuit board 15 on which circuit components of the magnetic disk device are mounted is disposed.

Further, as shown in the stator cross-sectional view of FIG. 2, the stator core 8 disposed around the outer periphery of the rotor magnet 7 has a plurality of slots 16, and the stator coil 9 is divided into multiple phases and wound (not shown). The rotational position of the rotor magnet 7 is detected by a magnetic sensor, and each phase of the stator coil 9 is sequentially energized to generate rotational driving force to rotate the magnetic disk 3.

By making the spindle motor structure of the magnetic disk device as shown in Figure 1, the rotational diameter of the rotor yoke is reduced to approximately half of that of the conventional one9, and there is no interference contact between the stator coil and the rotor yoke, which reduces the contact between the rotor yoke and the circuit board. The space between the stator coils and the stator core has also increased, and by arranging the stator core on the outer circumferential side of the rotor magnet, the heat dissipation area of the stator coil and stator core can be increased to about twice that of the conventional one.
The same bearings and seals as conventional parts can be used. The height of the spindle motor in the shaft direction can be made thinner than conventional ones by at least the thickness of the rotor yoke, and it can also be made thinner by improving the heat dissipation area of the stator core and eliminating interference between the rotor yoke and stator coil. This makes it possible to secure mounting space for the circuit board even under the spindle motor. Furthermore, the rotor yoke portion and the stator core portion can be assembled separately, which is effective in improving yield, improving assembly efficiency, and reducing costs. Furthermore, the circuit implementation can be made larger5.
The circuit board area of a 5-inch magnetic disk device (approximately 100
m++aX150mm area), it is possible to secure mounting space for interface circuits such as 5CSI, which is a magnetic disk controller, and is effective for high 8fk intelligent design, and for magnetic disks with an inner diameter of 40 mm or less, which have low reliability in in-hub motors. This method is effective for magnetic disk drives, and is even more effective when the height of the drive is less than half-hide.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to not only make the spindle motor of a magnetic disk drive smaller and thinner, but also improve reliability, improve assembly efficiency, and reduce costs. By applying it to devices, it is possible to increase the area of the circuit board, make the circuit more intelligent, and it is possible to adapt to higher capacity and higher performance of smaller and thinner magnetic disk devices.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts showing an embodiment of a spindle motor of the present invention. 3...Magnetic disk 6...Rotor yoke 7...Rotor magnet 8...Stator core 9...Stator coil and above Applicant: Seiko Epson Corporation Company 3: Article Niru Kuko 1 Kotsuto: Fukuku ° Hatat 2 ° Kuto - Hiroi q: Matasaki - 9 Kui J Shimatagon F) Shimo - 9th layer A and key r side - Figure 1 Pi: Sui-9ri9 9nisso-9i Ishit&ynear o,,tH Sue'r-9 dark side episode 2nd section

Claims (1)

[Claims] In a spindle motor of a magnetic disk device in which a magnetic disk serving as a magnetic recording medium has an inner diameter of 40 mm or less and a plurality of said magnetic disks are mounted and rotated to perform magnetic recording and reproduction, a rotor magnet is divided and magnetized into a plurality of poles. is arranged on the inner circumferential side of a stator coil that is divided into multiple phases and wound around a stator core having a plurality of slots on the inner circumferential side.