Disk drive spindle motor having a cavity defined by one of an upper surface of a stator support structure and a lower surface of a stator tooth

A spindle motor includes a shaft defining a longitudinal axis, a hub, a bearing assembly disposed between the hub and the shaft for allowing the hub to rotate, and a stator. The stator includes an inner diameter, an outer diameter, a stator tooth having a distal end, and a coil wound around the stator tooth. The stator tooth has a lower surface extending between the coil and the distal end of the stator tooth. The spindle motor includes a stator support structure supporting one of the inner and outer diameters, the stator support structure having an upper surface facing the lower surface, wherein at least one of the upper surface of the stator support structure and the lower surface of the stator tooth defines a cavity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a spindle motor used in a disk drive. More particularly, this invention relates to a spindle motor having a stator support structure supporting one of the inner and outer diameters of a stator.

2. Description of the Prior Art and Related Information

A huge market exists for disk drives such as hard disk drives for mass-market host computer systems such as servers, desktop computers, laptop computers, and consumer electronics devices such as a digital video recorder (“DVR”). To be competitive in this market, a hard disk drive must be relatively inexpensive, and must accordingly embody a design that is adapted for low-cost mass production. In addition, it must provide substantial capacity, rapid access to data, reliable performance, and in certain acoustic-sensitive applications such as consumer electronics devices, low acoustics. Numerous manufacturers compete in this huge market and collectively conduct substantial research and development, at great annual cost, to design and develop innovative hard disk drives to meet increasingly demanding customer requirements.

Each of numerous contemporary mass-market hard disk drive models provides relatively large capacity, often in excess of 80 gigabytes per drive. Nevertheless, there exists substantial competitive pressure to develop mass-market hard disk drives that have even higher capacities and that provide rapid access. Another requirement to be competitive in this market is that the hard disk drive must conform to a selected standard exterior size and shape often referred to as a “form factor.” Generally, capacity is desirably increased without increasing the form factor or the form factor is reduced without decreasing capacity.

Satisfying these competing constraints of low-cost, small size, high capacity, low acoustics, and rapid access requires innovation in each of numerous components and methods of assembly including methods of assembly of various components into certain subassemblies. Typically, the main assemblies of a hard disk drive are a head disk assembly and a printed circuit board assembly.

The head disk assembly includes an enclosure including a base and a cover, at least one disk having at least one recording surface, a spindle motor for causing each disk to rotate, and an actuator arrangement. The printed circuit board assembly includes circuitry for processing signals and controlling operations. Actuator arrangements can be characterized as either linear or rotary; substantially every contemporary cost-competitive small form factor drive employs a rotary actuator arrangement.

The spindle motor includes a stator, which typically includes a plurality of laminated stator teeth with a coil wound around the teeth. The stator may be attached to a surface of a spindle motor bracket such that the stator teeth and the coil are cantilevered; for example, an inner diameter of the stator may be attached to the surface of the spindle motor bracket. When the spindle motor is spun up in a disk drive, the stator may vibrate at its natural frequencies, generally between 10 KHz and 20 KHz. Such vibrations from the stator may lead to higher acoustics, which may exceed the acoustic requirements in certain acoustic-sensitive applications such as consumer electronics devices.

SUMMARY OF THE INVENTION

This invention can be regarded as a spindle motor for a disk drive. The spindle motor includes a shaft, a hub, a bearing assembly disposed between the hub and the shaft for allowing the hub to rotate, and a stator. The stator includes an inner diameter, an outer diameter, a stator tooth having a distal end, a coil wound around the stator tooth, the stator tooth having a lower surface extending between the coil and the distal end of the stator tooth. The spindle motor includes a stator support structure supporting one of the inner and outer diameters, the stator support structure having an upper surface facing the lower surface, wherein at least one of the upper surface of the stator support structure and the lower surface of the stator tooth defines a cavity.

This invention can also be regarded as a disk drive including a base, a spindle motor attached to the base, and a disk supported by the spindle motor. The spindle motor includes a shaft, a hub, a bearing assembly disposed between the hub and the shaft for allowing the hub to rotate, and a stator. The stator includes an inner diameter, an outer diameter, a stator tooth having a distal end, and a coil wound around the stator tooth, the stator tooth having a lower surface extending between the coil and the distal end of the stator tooth. The spindle motor includes a stator support structure supporting one of the inner and outer diameters, the stator support structure having an upper surface, wherein at least one of the upper surfaces of the stator support structure and the lower surface of the stator tooth defines a cavity.

DETAILED DESCRIPTION

With reference toFIGS. 1-3and5, a disk drive10includes a base12, a spindle motor26attached to base12, and a disk16supported by spindle motor26. Spindle motor26includes a shaft62, a hub66, a bearing assembly68disposed between hub66and shaft62for allowing hub66to rotate, and a stator80. Stator80includes an inner diameter92, an outer diameter94, a stator tooth84having a distal end95, and a coil82wound around stator tooth84. Stator tooth84has a lower surface extending between coil82and distal end95of stator tooth84, the lower surface being generally denoted by99. Spindle motor26includes a stator support structure86supporting one of inner92and outer94diameters, stator support structure86having an upper surface facing lower surface99, the upper surface being generally denoted by98. Spindle motor26includes at least one of upper surface98of stator support structure86and lower surface99of stator tooth84defining a cavity102.

Continuing withFIG. 1, disk drive10includes a cover14, a printed circuit board22attached to base12, a head stack assembly28, and VCM plates60,58, each having a respective magnet56or54. Head stack assembly28includes an actuator body32, a coil portion50, a flex circuit assembly (not numbered) attached to actuator body32, and a pair of actuator arms34,36. Head stack assembly28includes a head gimbal assembly38attached to actuator arm34and a head gimbal assembly40attached to actuator arm36, with each head gimbal assembly having a respective head42or44. Head stack assembly28pivots relative to pivot axis48. Disk16includes a top recording surface18and a bottom recording surface20or alternatively, one of the recording surfaces may be used. In an alternative embodiment, a plurality of disks with a corresponding number of heads may be used in disk drive10.

Continuing withFIGS. 2-3and5, spindle motor26includes shaft62defining a longitudinal axis64, another bearing assembly70longitudinally spaced-apart from bearing assembly68, a bracket72, a back iron74, and a magnet76attached to hub66via back iron74, wherein cavity102is adjacent to magnet76, as shown in one embodiment. Shaft64may be a fixed shaft as shown, for example, inFIG. 2or a rotating shaft. Bearing assemblies68and70may suitably be ball bearing assemblies as shown inFIG. 2or a fluid bearing assembly. Bracket72includes an inner portion78, which in one embodiment is used to support inner diameter92of stator80, as best shown inFIG. 3. Bracket72includes a stator attachment surface96defined on inner portion78and stator support structure86is disposed between bracket72and lower surface99of stator tooth84. In one embodiment, stator support structure86supports outer diameter94of stator80with inner diameter92of stator80being attached to stator attachment surface96. Coil82is wound around each respective stator tooth. Bracket72includes an annular surface87upon which stator support structure86is suitably attached. In another embodiment, stator support structure86may be integrally formed with bracket72. As best shown inFIG. 3, stator tooth84includes an upper surface, generally denoted by88, which is symmetrical with lower surface99in accordance with an embodiment of this invention. In another embodiment, a stator support structure may support an inner diameter of a stator with its outer diameter being attached to a stator attachment surface.

Continuing withFIG. 5in which an enlarged view of an embodiment of this invention is shown, lower surface99includes a step106and upper surface98includes a step108. The height of each step may suitably be the thickness of approximately one to three laminations in stator80. Such steps may be suitably formed via a punching operation. In accordance with one embodiment, upper surface98and lower surface99define cavity102, via their respective steps108,106. In another embodiment, cavity102may be defined by either upper surface98or lower surface99. For example, lower surface99may extend generally horizontally to distal end95while upper surface98of stator support structure86defines a cavity. In one embodiment, lower surface99extends horizontally from one side of coil82and includes the surface defined by step106which extends to distal end95and upper surface98includes an inner annular surface and the surface defined by step108which extends to distal end95, as shown inFIG. 5. In one embodiment, spindle motor26includes an adhesive100disposed between upper surface98of stator support structure86and lower surface99of stator tooth84. Cavity102allows a portion of adhesive100to flow into cavity108thereby preventing adhesive100from leaking into gap104, the portion which may result from adhesive100applied to attach stator80to stator support structure86.

With reference toFIG. 4, bracket72, stator support structure86, and stator80are shown. In the embodiment shown, each stator tooth84extends out from an annular segment93which generally defines inner diameter92of stator80. In one embodiment, step108of upper surface98extends continuously around the periphery of upper portion98, as shown inFIG. 4. In another embodiment, step108may be formed intermittently around the periphery such that it is generally circumferentially coextensive with the distal “shoes” of each stator tooth. In one embodiment, bracket72may be part of a spindle motor which is then attached to a base of a disk drive. In another embodiment, bracket72may be integrally formed with a base of a disk drive.

With reference toFIG. 6in which another embodiment of this invention is shown, a cavity116is defined by lower surface99and an upper surface198of a stator support structure186. Cavity116includes a trough112adjacent to an annular surface114of upper surface198.