System, method and apparatus for wall slot in disk drive bypass channel for enhanced voice coil motor cooling

A hard disk drive bypass channel architecture incorporates enhanced cooling for voice coil motors. A cooling slot formed in a bypass channel component that is adjacent to the VCM alleviates VCM overheating problems. The slot compromises airflow from the bypass channel to provide sufficient secondary flow to cool the VCM and actuator coil area. The slot may be formed in the integrated wall of the spoiler or diverter. The spoiler has an extension in which the cooling slot is formed.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates in general to hard disk drives and, in particular, to an improved system, method, and apparatus for enhanced cooling of voice coil motors in hard disk drives.

2. Description of the Related Art

Data access and storage systems generally comprise one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. The hard disks themselves are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, one to five disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm). Hard disk drives have several different typical standard sizes or formats, including server, desktop, mobile (2.5 and 1.8 inches) and microdrive.

A typical HDD also uses an actuator assembly to move magnetic read/write heads to the desired location on the rotating disk so as to write information to or read data from that location. Within most HDDs, the magnetic read/write head is mounted on a slider. A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirably contacting the disk.

A slider is typically formed with an aerodynamic pattern of protrusions on its air bearing surface (ABS) that enables the slider to fly at a constant height close to the disk during operation of the disk drive. A slider is associated with each side of each disk and flies just over the disk's surface. Each slider is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid actuator arm that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single movable unit having either a linear bearing or a rotary pivotal bearing system.

The head and arm assembly is linearly or pivotally moved utilizing a magnet/coil structure that is often called a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which the spindle is also mounted. The base casting with its spindle, actuator VCM, and internal filtration system is then enclosed with a cover and seal assembly to ensure that no contaminants can enter and adversely affect the reliability of the slider flying over the disk. When current is fed to the motor, the VCM develops force or torque that is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head approaches a desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop and settle directly over the desired track.

During operation, the VCM is prone to heat up to maintain fast seek times in high performance server class disk drives. Accordingly, the temperature of the VCM must be monitored since excessive temperature can degrade performance of the drive. In some operating environments and severe cases, the high temperatures generated by disk drives can melt the coil insulation and coating, thus resulting in catastrophic failures in the drive, such as outgassing, contamination, etc.

Some disk drives utilize a bypass channel to regulate airflow within the disk drive. With bypass architecture, the airflow is stripped from the disk pack, commonly by a diverter or spoiler, and diverted into the bypass channel. Ideally, the bypass channel should have no interruptions or leakage in order to maintain the airflow momentum throughout the channel. Unfortunately, this poses a dilemma for temperature-sensitive areas of the drive, such as the VCM, since bypass channels allow little or no flow into the VCM area. Thus, an improved airflow solution that satisfies the multiple and sometimes conflicting interests of bypass architecture would be desirable.

SUMMARY OF THE INVENTION

Embodiments of a system, method, and apparatus for enhanced cooling of VCMs in hard disk drives are disclosed. The invention helps alleviate overheating problems with VCMs by slightly compromising the airflow from the bypass channel. Sufficient secondary flow is provided to cool the VCM and actuator coil area. In one embodiment, the spoiler or diverter forms an integrated wall with the bypass channel that serves as an extension to the channel wall, which may be cast into the base casting of the disk drive enclosure. The spoiler, as a channel wall extension, is provided with a cooling slot that can be varied according to the cooling capacity required for specific disk drives and designs. The invention provides a significant increase in coil cooling capacity for slot geometries over previous designs with no slot provided.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1 and 2, one embodiment of a system, method, and apparatus for an information storage system comprising a magnetic hard disk file or drive111for a computer system is shown. Drive111has an outer housing including a base113and top cover (not shown). The housing contains a disk pack having at least one media disk, e.g., magnetic disk115. The disks115are rotated (see arrows205) by a spindle motor assembly having a central drive hub117. An actuator121comprises a plurality of parallel actuator arms125in the form of a comb that is pivotally mounted to base113about a pivot assembly123. A controller119is also mounted to base113for selectively moving the comb of arms125relative to disk115.

Each arm125has extending from it at least one cantilevered load beam and suspension127. A magnetic read/write transducer or head is mounted on a slider129and secured to a flexure that is flexibly mounted to each suspension127. The read/write heads magnetically read data from and/or magnetically write data to disk115. The level of integration called the head gimbal assembly (HGA) is the head and the slider129, which are mounted on suspension127.

Suspensions127bias the air bearing surface of the slider129against the disk115to cause the slider129to fly at a precise distance from the disk. A voice coil133free to move within a voice coil motor magnet assembly (not shown) is also mounted to arms125opposite the head gimbal assemblies. Movement of the actuator121(indicated by arrow135) moves the head gimbal assemblies along radial arcs across tracks on the disk115until the heads settle on their respective target tracks. The head gimbal assemblies operate in a conventional manner and always move in unison with one another, unless drive111uses multiple independent actuators (not shown) wherein the arms can move independently of one another.

The disks115define an axis201of rotation and a radial direction207. The disks115have a downstream side213wherein air flows away from the disks115, and an upstream side215wherein air flows toward the disks115. The drive111also has a bypass channel219located in the housing113for directing the air flow generated by rotation of the disks115from the downstream side213of the disk pack or disks115to the upstream side215of the disks115. In this way the airflow substantially bypasses the actuator121and voice coil motor assembly.

In the embodiment shown, the bypass channel219is located between an outer perimeter217of the housing113and the actuator121, such that the bypass channel219completely circumscribes the actuator121. The elements that define the bypass channel219may be integrally formed (e.g., cast) with the base113. In some HDD designs where there is insufficient space to implement a full bypass channel (shown) the bypass channel219may be abbreviated (not shown), which is known as a partial bypass. Furthermore, in order to help the bypass airflow negotiate substantial angular changes (channel bends), one or more turning vanes may be placed in those areas.

The drive111also may comprise a slot300that is located adjacent to the voice coil motor assembly. The slot300is designed to be integrated and work with the bypass channel219for diverting a portion of the overall airflow toward and through the voice coil motor assembly. The bypass channel219includes inner and outer walls301,303that define the conduit for the airflow. The slot300comprises an opening that is formed in the inner wall301next to the magnet, and may comprise a same axial dimension as that of the inner wall301. The slot300may span a linear gap (i.e., generally in a radial direction relative to the disk115) of approximately 1 mm to 20 mm. For example, a typical 3.5-inch server class drive the gap may comprise about 5 mm. As shown in the drawings, the slot300may comprise a flat rectangular hole.

As shown in the illustrated embodiment ofFIGS. 1 and 2, the slot300in the inner wall301of the bypass channel219is located on the downstream side213(referenceFIG. 1) of the media disk115. The slot300may be defined between a spoiler or diverter311, which forms an integrated wall with the bypass channel219, and the inner wall301formed in the base casting113. An extension313extends from the diverter311toward the inner wall301. The distance between the end of the extension313on the diverter311defines the cooling slot300. The location and size of the slot300may be varied according to the cooling capacity required for the VCMs of specific disk drives and designs.

As shown inFIG. 3, the invention provides a significant increase in coil cooling capacity for slot geometries over previous designs with no slot provided. For example, plot321depicts the coil temperature in a conventional disk drive having no cooling slot, while plot323depicts a drive equipped with the cooling slot of the present invention.

Referring now toFIG. 4, the invention also comprises a method of directing airflow in a disk drive. In one embodiment the method comprises providing the disk drive with a media disk, an actuator having a voice coil motor assembly, and a bypass channel (step401); directing airflow around the actuator with the bypass channel (step403); diverting a portion of the airflow from the bypass channel directly toward the voice coil motor assembly for cooling the voice coil motor assembly (step405); before ending as indicated. The method may further comprise other embodiments as shown and described herein.