System and method for maintaining a low density gas environment in a disk drive

A system and method for decreasing power consumption of hard disk drives through use of an external atmosphere of low density gas, such as helium, is described. An environment container reasonably resistant to diffusion and leakage of helium (container) is erected around an existing hard disk array or server, wherein a helium mixture is pumped into the container. The helium mixture within the container is maintained at a specified concentration via proper tubing and valves which may be manually or automatically controlled. The actual concentration need not be very pure in order to achieve reduced drag over the disks in each of the hard disk drives, thereby achieving reduced power consumption. The environment container is stand alone from the hard disk drives used such that an altered hard disk apparatus is unnecessary.

FIELD OF THE INVENTION

The present invention relates to the field of electronic data storage and hard disk drive performance. The present invention more particularly relates to creating an atmosphere of low density gasses such as helium or helium mixtures to lower the power consumption of the drive or drives.

BACKGROUND OF THE INVENTION

Presently many organizations have a need for storing large quantities of data, to address this need, organizations will acquire massive disk drive arrays which each require a substantial amount of power to operate. Due to this, these organizations amass considerably large power costs.

In general, the majority of hard disk drives (HDD) are operated in a standard air (nitrogen, oxygen and water vapor mixture) atmosphere. Spinning disks in HDDs at high RPMs against the friction of an air atmosphere is what drives power costs and is largely inefficient. By running the HDD in an atmosphere which is less dense, such as an atmosphere composed of helium or a helium mixture, friction on the disk is reduced thereby causing the disk to require less power in order to spin at a similar rate.

In using a lower density atmosphere to reduce power costs, maintaining helium or a helium mixture inside the drive rather than a standard air mixture at a reasonable cost can pose additional problems. If the HDD is to be sealed, such that it maintains its own atmosphere, the drive will be prone to pressure differences between inside and outside the drive which produces mechanical stress that requires a more robust mechanical design. An additional problem arises when preventing leaking of internal helium during the operating life of the HDD (5 years). Special metal seals or welding have to be used to seal the drive properly.

Due to this all drives contain a breather hole which equalizes pressure inside and outside of the drive. However, a breather hole allows gas exchange and the helium would diffuse out after a relatively short period. Prior art has addressed this problem by welding the drive shut or adding metal seals. Additionally to withstand the potential pressure differences between inside and outside of the drive, prior art has mechanically reinforced the drive case in order to avoid warping of the critical precision drive mechanics. However, these prior techniques all call for heavy modification of production lines.

Accordingly, there is a need for an improved system that can effectively supply a HDD with a low density gas, such as helium, during use at low cost involving little to no changes to present production lines. The present invention provides a solution to this and other problems, and offers other advantages over the prior art.

BRIEF SUMMARY OF INVENTION

This and other objects of the present invention are made obvious in light of this disclosure, wherein methods and systems for maintaining a helium mixture environment within a hard disk drive (HDD) are described.

According to a first aspect of the system of the present invention, an external environment container reasonably resistant to diffusion and leakage of helium (container) is erected around a hard disk array or server, wherein a helium mixture is pumped into the container. The helium mixture and uniformity within the container is maintained at a specified concentration via proper tubing, fans, heat sinks and valves which may be manually or automatically controlled. Before being placed in the container, the HDDs in the array tower will be acclimated to a low density environment with separate helium filled enclosures and equalize via a standard breather hole that all commercial drives posses; thereby filling with a certain concentration of helium which closely matches the helium mixture in the container. The actual concentration of helium need not be very pure in order to achieve reduced drag over the disks in each of the HDDs, thereby achieving reduced power consumption.

According to a first preferred embodiment of the method of invention, the container begins full of air. A helium mixture is injected into the container, as pressure builds inside the container an over pressure valve is opened preferably at the base of the container allowing gas to escape easily. The container, being reasonably sealed, does not allow a significant amount of ambient air to enter, thus eventually all that remains within the container is a helium mixture. The helium mixture can be set for a constant or intermittent flow. The pre-acclimated hard drive array is then placed in the container, which will lose some helium mixture, and take on some air in the process. The container is sealed and the helium mixture flushes out the air over time thereby maintaining the helium mixture atmosphere.

INCORPORATION BY REFERENCE

All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference in their entirety and for all purposes to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

The publications discussed or mentioned herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Furthermore, the dates of publication provided herein may differ from the actual publication dates which may need to be independently confirmed.

DETAILED DESCRIPTION

It is to be understood that this invention is not limited to particular aspects of the present invention described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as the recited order of events.

The term, “helium mixture” is to be expressly defined for the purposes of this disclosure as any of the following: pure atomic helium, crude helium, and an air/helium mixture or gas/helium mixture composed of at least 50% helium by volume which can also contain typical environmental gas contaminants like moisture, carbon dioxide, sulfur compounds, and heavier hydrocarbons as also found in crude helium.

Referring now toFIG. 1, a block diagram of a hard disk drive (Hereafter “HDD”)2. Standard commercial HDDs2presently all include at least one disk4, each with a matching head6poised on an arm controlled by an actuator8. These components are housed within a casing10which is effectively enclosed except a small breather hole12on the surface which allows for gas exchange inside and outside of HDD2to avoid pressure differences. The breather hole12contains a particle filter14to keep inflow gas clean.

Referring now toFIG. 2, a diagram of the invented external environmental system (hereafter “environmental system”)16. The environmental system16comprises a substantially air-tight, to completely air-tight container18with one or more hatches20, a gas inlet22, a heat exchanger24, an internal fan25, an electrical/data inlet26, a humidifier28, a gas supply30, an optional pressure sensor32, an optional gas mixture sensor34and an over pressure valve36. Placed inside the environmental system16would be one or more HDDs2, a HDD array2acontaining a plurality of HDDs2or server3which would comprise at least one HDD2and a controller. The substantially air-tight container (hereafter “container”)18would be constructed of sheet metal, plastic, plexiglass, or any other suitable material known in the art such that, when closed, the container18, is ideally sealed from ambient air transfer; however, marginal air seepage would still be acceptable. Actual construction and air seal strength would depend on cost of materials and many on-site variables. The container18need not be rigid in form, and could be constructed as a flexible bag in character as long as other specified characteristics were adhered to. The container18need not be vacuum tight and depending on material used or strength of the seals, some helium gas may diffuse out. Depending on the effectiveness the seal on the container18, it is foreseen that a completely air tight container18would not take on additional air, but would still lose helium mixture through diffusion. Helium mixture loss would be detected by either the optional pressure sensor32or a gas mixture sensor34and would then be replenished by the gas supply30. When the pressure within the container18becomes greater than that outside the environmental system16, an over pressure valve36would open, allowing gas to escape thus lowering the pressure inside the environmental system16.

The hatch20or the container18should be sealed with a rubber o-ring like device, a viton seal or any other suitable material known in the art such that when closed the seal prevents at least a substantial majority of air seepage. In order to maintain a helium mixture atmosphere within the container18while access to objects inside the environmental system16is required via the hatch20, the container18could be configured to maintain an internal pressure slightly above ambient atmosphere which would be established by the gas supply30and adding additional resistance to the over pressure valve36. The increased internal pressure would create an outward diffusion of gas for a short period until the pressure equalized such that limited ambient air would be able to enter the environmental system16. Additionally rather than a single hatch20, several smaller hatches20could be utilized one or more at a time in order to expose less open surface area when accessing the environmental system16. Alternatively or in addition to the aforementioned method, the environmental system16could be flushed with helium mixture from the gas supply30every time access was needed.

The electrical/data inlet26would be constructed such that it would accommodate the proposed contents of the environmental system16. The electrical/data inlet26would be substantially air tight similar to other apertures of the container18. In order to achieve this, an electrical and data BUS could be sealed into the wall of the container18or hatch(es)20and the HDD(s)2inside would connect to the internal end of the BUS and the external end would connect to a power source and the destination of the data stored in the HDD(s)2.

The heat exchanger24and internal fan25are used to maintain a specified temperature and uniform mixture of atmosphere inside the environmental system16. The heat exchanger24would take on one of many embodiments such that it would suitably dissipate heat created within the environmental system16. Gasses such as helium create less friction with the moving parts of a HDD2and thus will contribute to HDDs2generating less heat, further Helium changes temperature much less, requiring less heat dissipation. Refer to table 1;

TABLE 1HeliumAirHelium isDensity (gm/cm{circumflex over ( )}3)1.70E−041.20E−037× lowerViscosity (μPoise)194182.7similarThermal Conductivity1.50.266× better(W/cm-K)
Some suitable heat exchange methods would include systems similar to either an automobile radiators or a refrigerator. Another example of a suitable heat exchanger would be a cooling fin affixed to the surface of the container to increase said container's surface area, thereby supplying more material to absorb and subsequently dissipate heat to the exterior air. Other systems could also be feasible as long as they were able to adequately dissipate the heat generated by the chosen number of HDDs2to be kept within the environmental system16. The internal fan25would be affixed to either the top of the container18preferably facing down or the base of the container18preferably facing up. The optimal positioning on either surface would vary depending on specific construction of the container18. The purpose of the internal fan25would be to mix the lighter low density gas (helium mixture), with the heavier gasses present (such as air) which would otherwise gradually settle on the bottom of the container18. Natural convection caused by the heated drives will also contribute to the mixing.

The humidifier28is used as a result that standard commercial HDDs2work better with some humidity. An environment of less than 10%rh can cause problems in HDDs2currently in production. As a result that bottled helium is generally very dry, a humidifier is necessary to keep humidity in a range favorable for HDD2running conditions, between 10%-60%rh. Future HDDs may function effectively without humidity; this would negate the need for a humidifier in the present invention.

Referring now toFIG. 3, a cross section of an alternate embodiment of a gas inlet22a. The alternate gas inlet22awould include several valves38. The valves38could be controlled either manually or electronically. Each valve38would restrict access to one of three tubes40,42,44some of which being optional. The low density gas tube40would allow for the injection of a low density gas, such as a helium mixture, to the environmental system16via the gas supply30. The heavy gas tube42is optional and would allow for the flushing of a certain amount of a heavier gas, such as ambient air, and could be used as a cost saving measure, among other uses. The third tube, the humidity tube44, is optional and would replace the humidifier26while performing the same purpose. Referring toFIG. 3A, a duel gas inlet system is shown. In this case the low density tube40would be placed at the top of the container18and a high density gas tube42would be preferably placed at the base of the container18such that these lines could be operated independently. Further the high density gas tube42would be affixed to a vacuum pump. The heavier air could be drained from the container18from the base while the lighter helium mixture was flushed in from the top. This alternate embodiment would alleviate much of the need for the internal fan25.

Referring now toFIG. 4, a flow chart of a preferred method of environmental system16operations which may be carried out in any order of the recited events which is logically possible. First, the empty container18is sealed and through the gas inlet22, a low density gas such as a helium mixture is flushed into the environmental system16. As gas pressure builds inside the environmental system16an over pressure valve36at the base of the container18releases internal gasses, including air. During the low density gas flush, no substantial amount of air is replaced within the container18and the environmental system gradually attains a low density atmosphere such as an atmosphere composed of helium mixture (402). Next, the HDDs2that will be placed within the environmental system16are acclimated to a low density environment (404). The HDDs2are then placed inside the environmental system16(406). After the environmental system16is sealed again, an additional low density gas flush would occur to restore the gas lost while inserting the HDD(s)2(408). The environmental system16then maintains desired environmental settings using some or all of the local instruments and devices: a gas concentration sensor32, a pressure sensor34, heat exchanger24, the internal fan25, the humidifier28, the over pressure valve36and the gas inlet22. The gas supply30would be configured to flush the container18with the low density gas such as a helium mixture by a constant, intermittent or instrument regulated flow to maintain the desired atmosphere in the environmental system16(410). While in use, the process may be ended at the discretion of a user (412). At some point it is likely that a user will want to change out one or more of the HDDs2that reside within the environmental system16, in the event of this, the process begins again at the acclimation of the replacement HDD2(414).

Referring toFIG. 5andFIG. 6, which are apparatus and method for preemptive acclimation of a HDD2to a low density environment. The apparatus involved includes an at least substantially air tight enclosure46in which a non-operational HDD2may be placed. The enclosure46has two valves38, a first valve38aused for pumping air out and a second valve38bfor pumping a low density gas in. In operation, a HDD2which is currently not in operation is placed within the enclosure46(600). The second valve38bof the enclosure46is closed (602). The ambient air is vacuumed from the enclosure46through the first valve38a(604). The first valve38ais then closed and the second valve38bis opened and the enclosure46is flushed with a low density gas such as a helium mixture (606). Both valves38a,38bare then closed and time is given to allow the HDD2to fill with the low density gas (608). The HDD2is then removed from the enclosure46and placed within the environmental system16. If there is considerable time between removal and placing inside the environmental system16, the breather hole12can covered with suitable adhesive covering during the wait to prevent unnecessary helium mixture leaking (610).

Referring now toFIG. 7, which is a block diagram of a modified hard disk drive (modified HDD)48. The modified HDD48has one or more additional breather holes12such that when placed in a new atmosphere, the modified HDD48will fill with the ambient gasses more quickly. Due to the resultant increased air flow a more robust chemical and particle filter14could optionally be used. These additional holes can be blocked up with a suitable adhesive covering50when the environment the modified HDD48operates without a need for additional gas exchange. The placement of the additional holes12can be positioned to target particular pressure zones within a modified HDD48. One breather hole12may be positioned such that it is over a low pressure zone and a separate breather hole12, would be positioned over a high pressure zone. With this configuration ambient gasses would be drawn through the internal portion of the modified HDD48further increasing the rate the drive would fill with ambient gas.

Referring now toFIG. 8which shows a side view of a sample flying height of a head6in a HDD2. While running in a low density system the head6of a HDD2will have a lower flying height h, and in turn a smaller clearance d. Generally all drives address this issue by detecting touchdowns or near touchdowns, measuring or approximating the distances h and d, then cooling or heating the protrusion52as necessary to change the distance d. This method is shown inFIG. 10. The flying height h would be greatly altered by a moderate to substantial change in environment of the HDD2. Great changes in flying height can cause needless touchdowns which cause damage to the disc4or head6, and thus avoiding moderate to substantial transition phases would be ideal for an operator of the invented environmental system16. It is thus important for a user to minimize time in which the environmental system is exposed to external conditions such that transition phases remain small or negligible. Subsequent to this disclosure, HDDs2will have an improved ability to detect flying height changes as a result of transitions in environment, thus the care required by a user will decline over time.

Other changes that could potentially be made to HDD2design would include; the airbearing design could be optimized for operating in a helium mixture environment; the storage density can be increased because the low density environment allows for higher track densities due to less non repeatable run out, only the drives2firmware needs to have the provision to make use of this capability; and due to low density environment, drives2could spin at higher RPM than in ambient air which would offset some of the power savings but still be a beneficial application for the above mentioned environmental system16.

Referring toFIG. 9, which is a plurality of environmental systems16. The invented environmental system can be used in series with others using the same gas supply30and data/electrical bus54. In series, the invented environmental system16each containing HDD arrays2a, or servers3can save on power consumption over a much larger scale.

The foregoing disclosures and statements are illustrative only of the present invention, and are not intended to limit or define the scope of the present invention. The above description is intended to be illustrative, and not restrictive. Although the examples given include many specifics, they are intended as illustrative of only certain possible applications of the present invention. The examples given should only be interpreted as illustrations of some of the applications of the present invention, and the full scope of the Present Invention should be determined by the appended claims and their legal equivalents. Those skilled in the art will appreciate that various adaptations and modifications of the just-described applications can be configured without departing from the scope and spirit of the present invention. Therefore, it is to be understood that the present invention may be practiced other than as specifically described herein. The scope of the present invention as disclosed and claimed should, therefore, be determined with reference to the knowledge of one skilled in the art and in light of the disclosures presented above.