Airflow channel within a disc drive housing

A base support member for a disc drive is provided. The base support member includes a disc support cavity configured to house and support a spinning disc, and a component support cavity configured to house and support a set of electrical and mechanical disc drive components. The base support member also includes at least one surface that defines an airflow channel that is generally disposed within the component support cavity of the base support member. The airflow channel has an inlet opening positioned in a first location proximate the disc support cavity and an outlet opening positioned in a second location proximate the disc support cavity. The airflow channel is configured to receive a flow of air from the spinning disc at the inlet opening and to discharge the flow of air at the outlet opening.

FIELD OF THE INVENTION

The present invention relates generally to the field of data processing systems, and more particularly but not by limitation to disc drive data storage devices.

BACKGROUND OF THE INVENTION

Within data processing systems, disc drives are often used as data storage devices. A typical disc drive includes a rigid housing or deck that encloses a variety of disc drive components. The components include one or more discs having data surfaces that are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor that causes the discs to spin and the data surfaces of the discs to pass under respective hydrodynamic or aerodynamic bearing disc head sliders. The sliders carry transducers, which write information to and read information from the data surfaces of the discs.

An actuator mechanism moves the sliders from track-to-track across the data surfaces of the discs. The actuator mechanism includes a motor, such as a voice coil motor, that is generally disassociated from the discs in terms of its relative position within the disc drive housing. The actuator mechanism also includes, for each slider, a track accessing arm and a suspension. The slider is connected to the suspension. The suspension is connected to one end of the track accessing arm. The other end of the track accessing arm is operably connected to the motor. Under the control of electronic circuitry, the motor is operated so as to move the track accessing arm and its related suspension. In this way, each slider is moved from track-to-track across the data surface of a disc.

Within disc drives that include more than one disc, a single track accessing arm can be positioned between two discs, and two suspensions can be connected to the single track accessing arm. Accordingly, each of the two suspensions is connected to a separate slider. One of the sliders is configured to facilitate transfers of data to and from a bottom data surface of one disc, while the other slider is configured to facilitate transfers of data to and from a top data surface of another disc.

Each suspension typically includes a load beam and a gimbal. The load beam provides a load force that forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated into the load beam, to provide a resilient connection that allows the slider to pitch and roll while following topography of the data surface of a disc.

The slider typically includes a bearing surface, which faces the data surface of a disc. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compresses along the air flow path and causes the air pressure between the disc and the bearing surface to increase. This increase in air pressure creates a hydrodynamic or aerodynamic lifting force that counteracts the load force and causes the slider to lift and fly above or in close proximity to the data surface of the disc.

With increasing disc capacity and evolving disc drive performance requirements, it has become desirable, under certain circumstances, to increase the rotational speed of the discs in the disc drive. During disc drive operation, increases in disc rotational speed can cause the sensitive transducer-carrying sliders to experience undesirable turbulence and increased resonant amplitude due to windage-related excitation of the sliders themselves, as well as windage-related excitation of the discs, the actuator mechanism and other mechanical parts located within the disc drive housing.

One way to reduce windage-related interference is to include a shroud around the disc pack so as to significantly confine airflow to the disc pack area. The structure of the track accessing arms, however, generally prevents the inclusion of a shroud that surrounds the disc pack in its entirety. The structure of the actuator mechanism therefore complicates the concept of a complete shroud.

Many known disc drive designs allow, and in some instances encourage, the flow of air out of the disc pack area towards the various mechanical and electrical components of the disc drive. This flow of air towards the disc drive electrical and mechanical components outside of the disc pack area can cause the slider to experience considerable windage-induced turbulence. In addition, air that escapes the disc pack area is typically able to indiscriminately re-enter the disc pack area, thereby causing the slider to experience additional windage-induced turbulence on a somewhat random basis. Regardless of its source, windage-induced turbulence can have a negative impact on slider performance during critical read-write operations.

Some known disc drive designs actively encourage air to flow out of the disc pack area. The rationale behind several of these designs is to enable a cooling of various temperature-sensitive disc drive components, such as a voice coil motor portion of an actuator mechanism. With recent developments, including advances in coil temperature control, temperature can be effectively influenced without reliance on airflow-oriented cooling solutions, which can compromise slider performance.

Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.

The present invention relates to data storage devices that include housing features that influence airflow during device operation, wherein said features address at least the above-mentioned problems.

One embodiment of the present invention pertains to a base support member for a disc drive. The base support member includes a disc support cavity configured to house and support a spinning disc, and a component support cavity configured to house and support a set of electrical and mechanical disc drive components. The base support member also includes at least one surface that defines an airflow channel that is generally disposed within the component support cavity of the base support member. The airflow channel has an inlet opening positioned in a first location proximate the disc support cavity and an outlet opening positioned in a second location proximate the disc support cavity. The airflow channel is configured to receive a flow of air from the spinning disc at the inlet opening and to discharge the flow of air at the outlet opening.

Another embodiment pertains to a method of channeling airflow created by a disc that is configured to rotate within a housing of a disc drive. The method includes the steps of forming the housing, providing an airflow inlet opening within the housing and positioning the airflow inlet opening in a first location proximate an outside diameter of the disc. The method also includes the steps of providing an airflow outlet opening within the housing and positioning the airflow outlet opening in a second location proximate the outside diameter of the disc, the first location being displaced along the outside diameter from the second location. In addition, the method includes the steps of providing an airflow path within the housing and positioning the airflow path so as to provide airflow communication between the airflow inlet opening and the airflow outlet opening.

Another embodiment pertains to a disc drive that includes a rotatable storage disc and a disc head slider adapted to access data stored on a surface of the disc. The disc drive also includes an actuator mechanism for moving the disc head slider across the surface of the disc. The disc drive further includes read/write circuitry, which is coupled to the disc head slider. In addition, the disc drive includes a base support member for supporting the disc, actuator mechanism, disc head slider and read/write circuitry. The disc drive also includes means for guiding airflow within the base support member during operation of the disc drive.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention provides various embodiments of a new airflow channel mechanism within a disc drive housing. The new airflow channel mechanism reduces the amount of airflow that is guided directly at disc head sliders and their suspension systems using disc drive operation. In addition, the new airflow channel mechanism reduces the amount of air that is allowed to circulate towards sensitive mechanical and electrical disc drive components during disc drive operation. Further, the new airflow channel mechanism reduces the amount of airflow that is allowed to indiscriminately exit and reenter the disc pack region during disc drive operation. Generally speaking, the new airflow channel mechanism is configured to intercept airflow from a location “upstream” of the disc head sliders, to channel the air-flow around sensitive mechanical and electrical disc drive components, and to discharge the airflow in a location “downstream” of the disc head sliders.

FIG. 1is an isometric view of a disc drive100in which embodiments of the present invention are useful. Disc drive100includes a housing with a base support member102and a top cover (not shown). Disc drive100further includes a disc pack106, which is mounted on a spindle motor (not shown) by a disc clamp108. Disc pack106includes a plurality of individual discs107, which are mounted for co-rotation about central axis109. Each disc surface has an associated slider110which is mounted to disc drive100and carries a read/write head for communication with the disc surface. The read/write head can include any type of transducing head, such as an inductive head, a magneto-resistive head, an optical head or a magneto-optical head for example.

In the example shown inFIG. 1, sliders110are supported by suspensions112which are in turn attached to track accessing arms114of an actuator116. The actuator shown inFIG. 1is of the type known as a rotary moving coil actuator and includes a voice coil motor (VCM), shown generally at118. Voice coil motor118rotates actuator116with its attached sliders110about a pivot shaft120to position sliders110over a desired data track along a path122between a disc inner diameter124and a disc outer diameter126. Voice coil motor118is driven by servo electronics128based on signals generated by sliders110and a host computer (not shown). Other types of actuators can also be used, such as linear actuators.

During operation, as discs107rotate, the discs drag air under the respective sliders110and along their air bearing surfaces in a direction approximately parallel to the tangential velocity of the discs. As the air passes beneath the air bearing surfaces, air compression along the air flow path causes the air pressure between the discs and the air bearing surfaces to increase, which creates a hydrodynamic or aerodynamic lifting force that counteracts the load force provided by suspensions112and causes the sliders110to lift and fly above or in close proximity to the disc surfaces.

Base support member102is illustratively a rigid housing that holds the various internal features of disc drive100. During operation of disc drive100, the rotation of discs107induces significant air movement within base support member102. This air movement can cause sliders110to experience windage-induced turbulence, thereby compromising the flight performance of the sliders and the data transfer effectiveness of their associated read/write heads. Some of the turbulence experienced by sliders110results when the rotation of discs107causes air to be temporarily thrust out of the disc pack106area and allowed to indiscriminately re-enter the disc pack106area. Also, sliders110can experience an increased resonant amplitude as a result of windage-induced excitation of mechanical components, such as discs107, voice coil motor118, actuator116, track accessing arms114, suspensions112and other mechanical parts within base support member102. As disc drive spindle speeds are increased in order to increase the speed at which discs107rotate, the likelihood that sliders110will experience significant windage-induced turbulence also increases.

One way to reduce windage-induced error is to include a shroud feature around the disc pack. The structure of the track accessing arms of the actuator mechanism, however, generally prohibits the extension of a shroud feature around the disc pack in its entirety. In addition, having a shroud around the disc pack in its entirety would significantly increase the load placed on the spindle motor, which rotates the disc. Prior art base support members have incorporated a shroud feature around significant portions of the disc pack, with gaps left to accommodate mechanical components of the disc drive. In some instances, the coverage and extension of the shroud member has been specifically elected to reduce or optimize the load placed on the spindle motor.

FIG. 2is perspective view of a known base support member200. Base support200is configured for incorporation into a disc drive system. For example, base support member200could be substituted for base support member102within disc drive100(FIG.1). Base support member200has a disc support cavity202configured to house and support at least one rotatable disc. Also included is a component support cavity204configured to house and support certain components of an associated disc drive, such as a voice coil motor, an actuator pivot shaft and servo electronics. Base support member200further includes a shroud feature206. Shroud feature206partially encloses the disc support cavity202, but a significant gap is left open in areas proximate to component support cavity204.

It should be pointed out that cavities202and204have general and not absolute boundaries. For example, a disc or discs supported within cavity202could overlap into cavity204. Similarly, a component stored within cavity204could overlap into cavity202.

When base support member200is utilized within an operational disc drive system, the rotation of the disc or discs housed within support cavity202will cause air to be temporarily thrust out of cavity202and into component support cavity204. That same air is allowed to indiscriminately re-enter disc support cavity202, potentially having an adverse effect on the performance of disc head sliders and their associated transducers operating within the disc drive system. Also, when air flows out of disc support cavity202and into component support cavity204, a slider may experience an increased resonant amplitude as a result of windage-induced excitation of the disc drive's sensitive mechanical components (e.g., the discs, the voice coil motor, the actuator, the track accessing arms, the suspensions and other mechanical parts). In addition, shroud feature206will inherently guide a significant amount of airflow directly at the disc head sliders and their sensitive suspension systems, which could potentially have an adverse effect on slider performance.

Base support members having an upstream windage bypass design are known in the art and are generally designed to reduce the direct impact of windage on sliders and their suspensions.FIG. 3is perspective view of a known base support member300. Base support300is configured for incorporation into a disc drive system. For example, base support member300could be substituted for base support member102within disc drive100(FIG.1).

Base support member300has a disc support cavity302configured to house and support at least one rotatable disc. Also included is a component support cavity304configured to house and support components of an associated disc drive, such as a voice coil motor, an actuator pivot shaft and servo electronics. Base support member300further includes a bypass feature306. A significant opening exists between cavities302and304. The opening between cavities302and304is even larger than the opening included in base support member200(FIG.2).

It should be pointed out that cavities302and304have general and not absolute boundaries. For example, a disc or discs supported within cavity302could overlap into cavity304. Similarly, a component stored within cavity304could overlap into cavity302.

The design of base support member300enables some direct airflow to be channeled away from the disc head sliders and their sensitive suspension systems. The channeled airflow, however, is subsequently allowed, and even encouraged, to circulate towards sensitive mechanical disc drive components. Accordingly, the channeled airflow can cause the disc head sliders to experience turbulence, thereby having a negative impact on slider flight performance. In addition, the channeled air is able to indiscriminately re-enter cavity302, which is disadvantageous to slider performance.

FIG. 4is perspective view of a known base support member400. Base support400is configured for incorporation into a disc drive system. For example, base support member400could be substituted for base support member102within disc drive100(FIG.1). Base support member400has a disc support cavity402and a component support cavity404.

It should be pointed out that cavities402and404have general and not absolute boundaries. For example, a disc or discs supported within cavity402could overlap into cavity404. Similarly, a component stored within cavity404could overlap into cavity402.

Base support member400includes upstream air bypassing feature403. Feature403is configured to channel air out of cavity402and into cavity404. Feature403will enable some direct airflow to be channeled away from the disc head sliders and their sensitive suspension systems, however, the bypassing airflow will then circulate towards the sensitive mechanical disc drive components, which, for reasons explained above, can have a negative impact on slider flight performance. In addition, the channeled air is able to indiscriminately re-enter cavity402, which for reasons discussed above is disadvantageous.

FIG. 5is perspective view of a base support member500for a disc drive, in accordance with an illustrative embodiment of the present invention. Base support500is configured for incorporation into a disc drive system. For example, base support member500could be substituted for base support member102within disc drive100(FIG.1).

Base member500includes a disc support cavity502configured to house and support at least one rotatable disc. During operation of an associated disc drive system, the disc (or discs) spin or rotate about an axis in a manner similar to discs107described above in relation to FIG.1. Base member500also includes a component support cavity504, which is configured to house and support a set of electrical and mechanical disc drive components that could include, among other components, a voice coil motor and servo electronics, similar to those described above in relation to FIG.1.

It should be pointed out that cavities502and504have general and not absolute boundaries. For example, a disc or discs supported within cavity502could overlap into cavity504. Similarly, a component stored within cavity504could overlap into cavity502.

Base support member500further comprises an airflow channel506that is generally disposed within component support cavity504, but may, without departing from the scope of the present invention, extend into cavity502. Airflow channel506has an inlet opening508positioned in a first location proximate disc supporting cavity502and an outlet opening510positioned in a second location proximate disc supporting cavity502. Airflow channel506is generally configured to channel a flow of air that is created by a spinning disc (or a discs) during operation of a disc drive system within which base support member500has been incorporated. Airflow channel506illustratively receives a flow of air from the spinning disc or discs at inlet opening508, channels the air flow through channel506, and discharges the flow of air at outlet opening510.

Airflow channel506is partially formed by a wall512having an inwardly facing surface, wherein “inwardly,” generally means towards the interior portions of base support member500. As illustrated, wall512is integrally formed as part of base support member500. In accordance with another embodiment, however, wall512is a separate component that is attached within component support cavity504of base support member500. Airflow channel506is also partially formed by a wall514having an outwardly facing surface, wherein “outwardly,” generally means towards the exterior portions of base support member500. As illustrated, wall514is part of a protrusion518that is generally disposed within component support cavity504. In accordance with one embodiment, protrusion518is an integrally formed part of base support member500. In accordance with another embodiment, however, protrusion518is a separate component that is attached within component support cavity504of base support member500.

Referring toFIG. 5, the inwardly and outwardly facing surfaces of walls512and514face one another, are spaced apart from one another, and cooperate to form the walls of airflow channel506. Base support member500has an interior floor515. Airflow channel506illustratively includes a floor portion516. In accordance with one embodiment, floor portion516is generally contiguous and coplanar with floor515. In accordance with one embodiment, when a top cover (not shown) is placed over base support member500, air channel506has a top enclosure surface that is provided by that top cover.

It should be pointed out that airflow channel506may be formed utilizing structure other than the specifically illustrated channel. For example, airflow channel506could be formed utilizing a tubular member (having a single inner tubular surface) that is disposed within component support cavity504. The tubular member could have inlet and outlet openings similar to the airflow channel pictured in FIG.5. Similar airflow channels having other structural manifestations should also be considered within the scope of the present invention.

Component support cavity504illustratively has an actuator side520and an electronics side522. Actuator side520is generally the side of component support cavity504where the voice coil motor is supported. Electronics side522is generally the side of component support cavity where the servo electronics are supported. Inlet opening508is generally positioned proximate disc support cavity502on actuator side520of component support cavity504. Outlet opening510is generally positioned proximate disc support cavity502on electronics side522of component support cavity504.

It should be pointed out that sides520and522have general and not absolute boundaries. For example, an actuator element generally supported on side520could overlap onto side522. Similarly, an electronics element generally supported on side522could overlap onto side520.

Base support member500illustratively includes a peripheral edge524. In accordance with one embodiment, at least a portion of airflow channel506is generally disposed between peripheral edge524of base support member500and an actuating mechanism (e.g., a voice coil motor) supported on the actuator side520of component support cavity504. In addition, another portion of airflow channel506is also generally disposed between peripheral edge524of base support member500and electrical components (e.g., servo electronics) supported on the electronics side522of component support cavity504. Airflow channel506is generally disposed between the electrical and mechanical components stored within component support cavity504and peripheral edge524of base support member500.

In accordance with another embodiment, configurations of inlet opening508and outlet opening510are switched to accommodate opposite disc rotation within a disc drive system that incorporates base support member500(e.g., inlet opening508is on electronics side522). In accordance with yet another embodiment, inlet opening508is formed by surfaces so as to be aerodynamically shaped to encourage a pattern of airflow from a disc spinning within disc support cavity502to airflow channel506.

In accordance with one embodiment, inlet opening508further comprises an optional shroud portion526. Optional shroud portion526illustratively extends along the outside diameter of a disc supported within disc support cavity502, and generally blocks at least a portion of an actuator mechanism (e.g., a voice coil motor) from direct exposure to disc air flow. Optional shroud portion526is not a critical element of the present invention but could be provided, for example, to reduce or optimize the spin load place on the spindle motor which is charged with rotating the discs supported within disc support cavity502. Optional shroud portion526might also or alternatively be provided simply to shield certain components supported within component support cavity504from direct disc-generated air flow. The size and shape of airflow channel506and optional shroud portion526can be other than illustrated without departing from the scope of the present invention. Which sizes and shapes are most effective depends at least upon the nature, environment and characteristics of a given slider application.

FIG. 6is a perspective view of a base support member600. Base support member600is substantially similar to base support member500, but does not include optional shroud portion526. Elements inFIG. 6that are the same or similar to the elements of the previously described embodiment the present invention have been given the same or similar reference numerals. Referring to base support member600, the inlet does not include a shroud portion, but is illustratively aerodynamically designed to facilitate, enhance and encourage airflow through airflow channel606, which is, except for the lack of the shroud portion, is significantly similar to airflow channel506(FIG.5).

FIG. 7is a top plan view of a disc drive700that illustratively incorporates an embodiment of the present invention. Elements inFIG. 7that are the same or similar to the elements of the previously described embodiments the present invention have been given the same or similar reference numerals.

Disc drive700includes a housing with a base support member702and a top cover701(illustratively broken away to reveal internal drive700components). Disc drive700further includes a disc pack706, which is mounted on a spindle motor (not shown) by a disc clamp708. Disc pack706includes a plurality of individual discs707, which are mounted for co-rotation about central axis709. Each disc surface has an associated slider710which is mounted to disc drive700and carries a read/write head for communication with the disc surface. The read/write head can include any type of transducing head, such as an inductive head, a magneto-resistive head, an optical head or a magneto-optical head for example.

In the example shown inFIG. 7, sliders710are supported by suspensions712which are in turn attached to track accessing arms714of an actuator716. The actuator shown inFIG. 1is of the type known as a rotary moving coil actuator and includes a voice coil motor (VCM), shown generally at718. Voice coil motor718rotates actuator716with its attached sliders710about a pivot shaft720to position sliders710over a desired data track along a path722between a disc inner diameter724and a disc outer diameter726. Voice coil motor718is driven by servo electronics728based on signals generated by sliders710and a host computer (not shown). Other types of actuators can also be used, such as linear actuators.

During operation, as discs707rotate, the discs drag air under the respective sliders710and along their air bearing surfaces in a direction approximately parallel to the tangential velocity of the discs. As the air passes beneath the air bearing surfaces, air compression along the air flow path causes the air pressure between the discs and the air bearing surfaces to increase, which creates a hydrodynamic or aerodynamic lifting force that counteracts the load force provided by suspensions712and causes the sliders710to lift and fly above or in close proximity to the disc surfaces. It should be pointed out that disc drive700could, without departing from the scope of the present invention, include disc drive-related components other than those illustrated.

Base member702of disc drive700includes a disc support cavity802configured to house and support at least one rotatable disc. During operation of an associated disc drive system, the disc (or discs) spin or rotate about an axis in a manner similar to discs107described above in relation to FIG.1. Base member702also includes a component support cavity804, which is configured to house and support a set of electrical and mechanical disc drive components that could include, among other components, a voice coil motor and servo electronics, similar to those described above in relation to FIG.1.

It should be pointed out that cavities802and804have general and not absolute boundaries. For example, disc(s)707is generally supported within cavity802but overlaps into cavity804. A component stored within cavity804could similarly overlap into cavity802.

Base support member702further comprises an airflow channel806that is generally disposed within component support cavity804. Airflow channel806is illustratively configured and structured in a way that is substantially to the configuration and structure of airflow channel506in FIG.5. Airflow channel806has an inlet opening808positioned in a first location proximate disc supporting cavity802and an outlet opening810positioned in a second location proximate disc supporting cavity802. Airflow channel806is generally configured to channel a flow of air that is created by a spinning disc (or a discs) during operation of a disc drive700. Airflow channel806illustratively receives a flow of air from the spinning disc or discs at inlet opening808, channels the air flow through channel806, and discharges the flow of air at outlet opening810.

In accordance with one embodiment, inlet opening808is positioned in a first location proximate an outside diameter812of a disc707. Outlet opening810is positioned in a second location proximate the outside diameter812of the disc707. The disc707illustratively spins in a counter-clockwise rotation, along an arrow814, and inlet opening808therefore precedes outlet opening810relative to rotation of the disc707. Accordingly, airflow through airflow channel806is illustratively in the same direction as the disc, in the counter-clockwise direction. In accordance with one embodiment, inlet opening808receives a flow of air in a location that is “upstream” from slider (or sliders)110, channels that airflow through airflow channel806, and discharges the airflow out outlet810in a location that is “downstream” from slider (or sliders)110.

The airflow channels illustrated inFIGS. 5,6and7are advantageous in that they reduce the amount of direct airflow that is directly guided at the disc head sliders and their sensitive suspension systems. In addition, they reduce the amount of air that is allowed to circulate towards sensitive mechanical and electrical disc drive components. Also, they reduce the amount of airflow that is allowed to indiscriminately exit and re-enter the disc pack region. Air flow is intercepted “upstream” of the disc head sliders, channeled around sensitive mechanical and electrical disc drive components, and discharged in a location “downstream” of the disc head sliders.

In summary, one embodiment of the present invention pertains to a base support member (500,600,702) for a disc drive (700). The base support member (500,600,702) includes a disc support cavity (502,802) configured to house and support a spinning disc (707), and a component support cavity (504,804) configured to house and support a set of electrical and mechanical disc drive components (716,718,720,728). The base support member (500,600,702) also includes at least one surface that defines an airflow channel (506,606,806) that is generally disposed within the component support cavity (504,804) of the base support member (500,600,702). The airflow channel (506,606,806) has an inlet opening (508,808) positioned in a first location proximate the disc support cavity (502,802) and an outlet opening (510,810) positioned in a second location proximate the disc support cavity (502,802). The airflow channel (506,606,806) is configured to receive a flow of air from the spinning disc (707) at the inlet opening (508,808) and to discharge the flow of air at the outlet opening (510,810).

Another embodiment pertains to a method of channeling airflow created by a disc (707) that is configured to rotate within a housing (500,600,702and related top covers, e.g., top cover701) of a disc drive (700). The method includes the steps of forming the housing (500,600,702and related top covers, e.g., top cover701), providing an airflow inlet opening (508,608) within the housing (500,600,702and related top covers, e.g., top cover701) and positioning the airflow inlet opening (508,608) in a first location proximate an outside diameter (812) of the disc (707). The method also includes the steps of providing an airflow outlet opening (510,810) within the housing (500,600,702and related top covers, e.g., top cover701) and positioning the airflow outlet opening (510,810) in a second location proximate the outside diameter (812) of the disc (707), the first location being displaced along the outside diameter (812) from the second location. In addition, the method includes the steps of providing an airflow path (506,606,806) within the housing (500,600,702and related top covers, e.g., top cover701) and positioning the airflow path (506,606,806) so as to provide airflow communication between the airflow inlet opening (508,608) and the airflow outlet opening (510,810).