Patent Application
20090034125
The present invention relates to the field of hard disk drive development, and more particularly to a method and system for utilizing a load/unload ramp spoiler in a hard disk drive.
At least one hard disk drive (HDD) is used in almost all computer system operations. In fact, most computing systems are not operational without some type of HDD to store the most basic computing information such as the boot operation, the operating system, the applications, and the like. In general, the HDD is a device which may or may not be removable, but without which the computing system will generally not operate.
The basic HDD model includes a storage disk or hard disk that spins at a designed rotational speed. An actuator arm with a suspended slider is utilized to reach out over the disk. The slider is coupled with a suspension that supports both the body of the slider and a head assembly that has a magnetic read/write transducer or head or heads for reading/writing information to or from a location on the disk. The complete head assembly, e.g., the suspension, slider, and head, is called a head gimbal assembly (HGA).
In operation, the hard disk is rotated at a set speed via a spindle motor assembly having a central drive hub. There are tracks at known intervals across the disk. When a request for a read of a specific portion or track is received, the hard disk aligns the head, via the arm, over the specific track location and the head reads the information from the disk. In the same manner, when a request for a write of a specific portion or track is received, the hard disk aligns the head, via the arm, over the specific track location and the head writes the information to the disk.
Over the years, the disk and the head have undergone great reductions in their size. Much of the refinement has been driven by consumer demand for smaller and more portable HDDs such as those used in personal digital assistants (PDAs), Moving Picture Experts Group audio layer 3 (MP3) players, and the like. For example, the original HDD had a disk diameter of 24 inches. Modern HDDs are much smaller and include disk diameters of less than 2.5 inches. Advances in magnetic recording are also primary reasons for the reduction in size.
A second refinement to the HDD is the increased efficiency and reduced size of the spindle motor spinning the disk. That is, as technology has reduced motor size and power draw for small motors, the mechanical portion of the HDD can be reduced and additional revolutions per minute (RPMs) can be achieved. For example, it is not uncommon for a HDD to reach speeds of 15,000 RPMs. This second refinement provides weight and size reductions to the HDD, it also provides a faster read and write rate for the disk thereby providing increased speed for accessing data. The increase in data acquisition speed due to the increased RPMs of the HDD and the more efficient read/write head portion provide modern computers with hard disk speed and storage capabilities that are continually increasing.
However, the higher RPMs of the disk have resulted in problems with respect to the interaction of the air with components of the HDD. For example, although the HDD is closed off from the outside, it has an amount of air within its packaging. As the disk spins and the RPMs increase, the air within the HDD package will also begin to rotate and will eventually approach the speed at which the disk is rotating especially near the spindle hub and disk surfaces. This is due to the friction between the disk and the air. In general, Reynolds numbers are used to represent the flow characteristics. For example, in one case the Reynolds number may be based on the tip speed of the disk. That is, the linear velocity at the outer diameter of the disk.
Only when the Reynolds number is sufficiently small (e.g., an enclosure with reduced air density), the air may stay in steady flow with the boundary layer of air remaining smooth with respect to the rotating disk. However, any obstructions to the flow will result in turbulence.
As is well known from fluid dynamics, the characteristics of turbulent airflow can include buffeting, harmonic vibration, and the like. Each of these characteristics will result in problematic motion for the arm and head portion and/or the rotating disk. The problematic motion will result in excessive track miss-registration. This is even more significant as the tolerances are further reduced.
Currently, significant efforts are put into HDD design to minimize the problem caused by unsteady air flow such as airflow bypass channel designs and spoiler designs. For example, present HDD designs can have as many as four airflow components (upstream spoiler, downstream spoiler, slit shroud, and bypass channel), and each one of these components adds cost and manufacturing time.
A load/unload ramp spoiler for a hard disk drive is disclosed. One embodiment provides a load/unload ramp body having at least one load/unload ramp associated therewith, the at least one load/unload ramp for receiving at least one slider coupled with an actuator assembly. In addition, at least one spoiler is integrated with the load/unload ramp body to reduce detrimental local excitation of an airflow encountering the load/unload ramp body.
Reference will now be made in detail to the alternative embodiment(s) of the present invention. While the invention will be described in conjunction with the alternative embodiment(s), it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.
Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.
The discussion will begin with an overview of a HDD and components connected therewith. The discussion will then focus on embodiments of a method and system for utilizing a load/unload ramp spoiler to improve actuator dynamics, such as, flow induced vibration of a slider, an integrated lead suspension (ILS) trace and/or suspension components of a head gimbal assembly in particular.
In general, the integrated spoiler-finger load/unload ramp effectively reduces non-repeatable runout (NRRO) and track-follow track misregistration (TMR) caused by unsteady airflow and at the same time reduces cost, manufacturing assembly time, and is more effective in suppressing flow induced vibration of the slider, ILS trace and suspension components because its of its flow stagnation (“upstream waken).
With spindle motor/disk packs rotating at 15 k RPM, flow induced vibrations are the major detractor to HDD performance. With newer slider designs (Femto) that have much smaller air-bearing surface, the load/unload (L/UL) ramp becomes an essential component in preventing head/disk damage from non-operational shocks.
The presence of the L/UL ramp at the outer diameter (OD) of the disk makes the effects of airflow even more problematic when reading/writing at the OD. In prior art implementations, the L/UL ramp acts aerodynamically as an air break, consuming substantial aerodynamic power. However, utilization of the present technology suppresses flow induced vibration of (especially) the sensitive suspension, ILS and slider components. Moreover, if the present technology is used in conjunction with an aerodynamic bypass, the flow in the bypass channel will be increased. In addition, if the aerodynamic bypass includes a filter, such as a filter in the bypass wall, the flow through the filter will also be increased, resulting in reduced particle cleanup time.
With reference now to
A spindle motor assembly having a central drive hub 130 operates as this axis and rotates the disk 138 or disks of the disk pack in the radial direction relative to housing 113. An actuator assembly 120 includes a plurality of parallel actuator arms 125 in the form of a comb that is movably or pivotally mounted to base/housing 113 about a pivot assembly 145. A controller 150 is also mounted to base 113 for selectively moving the comb of arms relative to disk 138.
In the embodiment shown in
The ILS 129 has a spring-like quality, which biases or presses the air-bearing surface of slider 155 against disk 138 to cause slider 155 to fly at a precise distance from disk 138. ILS 129 has a hinge area that provides for the spring-like quality, and a flexing interconnect that supports read and write traces and electrical connections through the hinge area. A voice coil 133, free to move within a conventional voice coil motor magnet assembly, is also mounted to actuator arms 125 opposite the head gimbal assemblies. Movement of the actuator 120 by controller 150 causes the head gimbal assemblies to move along radial arcs across tracks on the surface 135 of disk. The head gimbal assemblies operate in a conventional manner and always move in unison with one another, unless HDD 110 uses multiple independent actuators (not shown) wherein the arms can move independently of one another.
HDD 110 also includes L/UL ramp body 232 with at least one integrated spoiler 233. In general, the L/UL ramp body 232 serves as a platform on which the ILS 129 and more specifically, slider 155 is able to rest when disk 138 is not spinning at operating speed. In one embodiment spoiler 233 may reach all of the way from OD 135 to the middle diameter (MD) 136.
The terms “middle diameter” and “outer diameter” are intended to be for illustrative purposes only. For example, the term MD 136 referrers to a portion of disk 138 that approximates the middle of the writable area of disk 138. In addition, the term OD 135 refers to a portion of disk 138 that approximates the outer portion of the writable area of disk 138. In another embodiment, the approximation may be based on the entire disk 138 without accounting for the writable area of disk 138.
Referring still to
In one embodiment, bypass channel 219 may include a diffuser 221. In one embodiment, diffuser 221 is located adjacent to the upstream side 151 of disk 138. In general, diffuser 221 is offset upstream from disk 138, such that the diffuser 221 reduces airflow drag from the disk 138 due to disk wake in the bypass channel 219. This type of aerodynamic drag is commonly called base drag.
In addition, bypass channel 219 may also include a contraction 222 for re-accelerating bypass airflow 160 to provide efficient energy conversion for the air flow from pressure energy to kinetic energy prior to merging bypass airflow 160 with air flow 140 around the disk 138. Each of the diffuser 221 and the contraction 222 may be spaced apart from the outer edges of the disks 138, for example, approximately 0.5 mm.
The use of bypass channel 219 has several advantages, including the ability to reduce aerodynamic buffeting of actuator 120 during the servo writing process and/or during normal operation of HDD 110. More specifically, bypass channel 219 reduces the pressure build-up on the upstream side of actuator 120 which occurs when HDD 110 is operated. Additionally, directing airflow 140 into the bypass channel 219 decreases the upstream pressure on the actuator, thus reducing force acting on the actuator 120 while reducing the energy of the bluff-body wake of the actuator arm.
In embodiments of the present invention, HDD 110 may be filled with a gas (e.g., helium) rather than ambient air. This may be advantageous in that helium is a lighter gas than ambient air and causes less buffeting of actuator 120 when HDD 110 is in operation. In embodiments of the present invention, HDD 110 may be sealed after the servo writing process to keep the helium in the HDD.
With reference now to
Actuator assembly 120 is coupled pivotally to base casting 113 by means of pivot bearing 145, whereby VCM 150 can move head 156 accurately across data tracks on disk 138. Upon assembly of actuator assembly 120, disk(s) 138, VCM 150, and other components with base casting 113, cover 112 is coupled to base casting 113 to enclose these components and sub-assemblies into HDD 110.
Referring now to
Thus, as slider 155 moves closer to OD 135, slider 155 will begin to encounter airflow disruption area 274 and the flow induced vibrations associated therewith. As slider 155 moves further toward OD 135 and further into airflow disruption area 274, the associated flow induced vibrations will continue to increase. As stated herein, as flow induced vibrations increase, so do NRRO and TMR. Moreover, as HDD designs continue to increase the RPM of disk 138, airflow disruption area 274 will increase in both size and strength, thereby causing flow induced vibration of slider 155, and other components of actuator assembly 120, significantly earlier than OD 135. Moreover, as HDD size decreases, airflow disruption area 274 will remain constant, thereby actually increasing the distance between the initial effects of airflow disruption area 274 as felt on slider 155 and the tracks remaining before slider 155 reaches OD 135.
With reference now to
Referring now to
Although approximate lengths and thicknesses are provided herein, they are merely a few of the possible embodiment and are provided for purposes of clarity. That is, the present technology is well suited to other length, width and thicknesses metrics and combinations of different variations with respect to each metric.
In one embodiment, the shape of spoiler 233 may be somewhat smaller than, but still follow the shape of, a portion of the arc actuator arm 125 circumscribes across disk 138. In one embodiment, the design or shape of spoiler 233 may be based on dimensional tolerances, the accommodation of manufacturing tooling requirements, and the like. In yet another embodiment, the shape of spoiler 233 may be any shape and not directly related to, or based on, the shape of actuator arm 125.
Although, in
In addition, while a number of spoiler 233 shapes are illustrated herein, this is not meant to be, and should not be, construed as a limitation of the shape of spoiler 233, Instead, it should be realized that it would be impossible to provide each and every shape to which spoiler 233 may be formed and the provided examples are merely for purposes of clarity.
Referring now to
With reference now to 402 of
Referring now to 404 of
In one embodiment, a plurality of spoilers 233 is integrated with L/UL ramp body 232. For example, the number of spoilers 233 may equal number of L/UL ramps 291. However, as stated herein, the number of spoilers 233 may also be greater or less than the number of L/UL ramps 291 present on the L/UL ramp body 232. In general, the leading edge of the at least one spoiler 233 is formed in the shape of an arc generated by a motion of the slider with respect to a surface of at least one disk.
Additionally, in one embodiment, the present technology also utilizes bypass channel 219 formed in housing 113 of HDD 110, to provide additional control of airflow 140. In addition, as described in
Thus, embodiments of the present invention provide a method and apparatus for utilizing a L/UL ramp spoiler to improve actuator dynamics, such as, flow induced vibration of a slider, an integrated lead suspension (ILS) trace and/or suspension components of a head gimbal assembly in particular. Additionally, a L/UL ramp body with integrated spoiler-finger effectively reduces NRRO and track-follow TMR caused by unsteady airflow. That is, the existence of the L/UL ramp body with integrated spoiler significantly improves the flow of air in and around the area of L/UL ramp.
Moreover, the present embodiments provide significant airflow improvements while remaining within the already limiting constraints of HDD real estate. Moreover, the benefits described herein are realized with minimal modification to the overall HDD manufacturing process in general and to the L/UL ramp structure manufacturing process in particular reduces part cost and manufacturing assembly time.
Example embodiments of the present technology are thus described. Although the subject matter has been described in a language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
