Abstract:
Flow guides in the form of extensions that project internally from the housing of an electronic consumer device can contribute to undesirable noise emissions from the device. Proposed is an improved flow guide or extension that reduces propagation of flow induced vibrations to the housing, thereby improving the overall acoustic performance of the device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional application No. 60/423,314, filed Nov. 1, 2002. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to improving the acoustic performance of electronic devices, and more particularly, but not by way of limitation, to structures or components that direct fluid flow in such devices. 
     BACKGROUND OF THE INVENTION 
     Products that generate less noise during operation are generally perceived as being superior to those that are noisy, even though the latter may outperform the former in other areas. Acoustic or noise control is therefore an important consideration in the design of many consumer products, examples of which include portable consumer electronics, personal entertainment systems, computers, and peripherals of such devices. 
     Vibration and noise may be induced by virtue of the way the product operates. This can be seen in a data storage device that includes a rotatable disc stack assembly in a housing. As the disc stack assembly rotates during drive operations, it drags along with it the surrounding air or fluid, thereby creating a movement of fluid within the housing. If the data storage device includes structure or devices that impede or redirect the fluid movement, fluid induced vibrations of the structure or devices may occur. Such vibrations may be amplified as they are transmitted to adjoining structure or devices. This contributes to the noise level of the data storage device, and thus adds to the overall noise level of the consumer product associated with the data storage device. Since the very structure and devices that resulted in the higher noise levels may be instrumental in improving the performance of the data storage device in other aspects, there is a need to provide for noise control without compromising the overall performance of the product. 
     The following provides examples of how the present invention provides a solution to meet this need while offering various other advantages to both the manufacturer and the consumer. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention include an extension projecting from a part of a housing component, where the extension has an elastic surface. The elastic surface is provided to face anticipated impingement of fluid flow so that the extension does not suffer from severe flow induced vibrations. The extension may be wholly or substantially formed from one or more elastic materials. The extension may be directly adhered to the housing component or otherwise coupled thereto. The extension and the housing component may be chosen to be of unlike materials to reduce or eliminate amplification of vibrations. The extension is designed for manufacturability in that it can be formed by extruding a material in the desired shape onto a housing component, the material being one that will adhere itself to the housing component. Alternatively, the extension may be attached to the housing component by a separate adhesive. 
     These and other features and advantages of the present invention will be evident from perusal of the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary disc drive incorporating one embodiment of the present invention. 
         FIG. 2  is a schematic diagram illustrating one embodiment of the present invention. 
         FIG. 3  is a perspective view of a housing component according to an embodiment of the present invention. 
         FIG. 4  is a flowchart detailing a method of forming the extension. 
         FIG. 5  and  FIG. 6  are top views of alternative embodiments. 
         FIG. 7  is a cross-sectional view of another alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Practical applications of the solution provided by the present invention will be illustrated with reference to a disc drive, although it will be understood that the solution can be applied to other electronic devices. 
       FIG. 1  shows an electronic device, such as a data storage device  100 , with its housing  110  taken apart to reveal the components therein. The housing  110  may be formed from a few components, for example, a base deck  112  and a cover  114 , both configured to mate upon assembly to form a sealable enclosure. The housing may be made from different materials, for example, steel, aluminum or plastic. Much of the drive operations may be controlled by circuitry found on a printed circuit board assembly that is attached to the base deck. 
     In the disc drive, data is written to and read from disc-shaped media by read/write heads  120 . One or more discs  122  may be mounted to a motor to form a disc stack assembly  124  that rotates during drive operations. The read/write heads  120  are supported by a suspension  125  that extends from an actuator arm  126 . A voice coil motor  127  is used to move the actuator arm  126  and thus position the read/write heads  120  with respect to the desired position on the disc. Communications between the read/write heads and the circuitry on the printed circuit board assembly may be effected through printed circuit cables  128  whose flexibility allow for the movement of the various mechanical components. 
     During drive operations, there is also movement of the air or fluid within the housing  110 . This may be more pronounced in the vicinity of the disc stack assembly  124  as the disc stack assembly may drag the surrounding fluid into motion with its own rotation. A disc drive may include one or more extensions that project internally into the enclosure from the housing, into the path of fluid flow. There are numerous applications for such extensions. For example, an extension may act as a guide to channel fluid flow towards a filtration unit so as to improve the efficiency of the filtration unit. In some drives, an extension may serve as a flow diverter for directing fluid flow away from certain components, particularly components that may be vulnerable to flow-induced resonant excitation such as the read/write heads. Also envisioned are extensions that are configured to encourage laminar flow or to prevent turbulent flow from developing. Such extensions may aggravate acoustic emissions from the disc drive because any transfer of kinetic energy from the fluid flow to the extension may create flow-induced vibrations in the extension, possibly causing the whole extension to engage in resonant vibration. The vibrations may be further amplified when transmitted to a plate-like housing component. However, this difficulty may be surmounted by an application of the present invention. In comparison with a conventional flow guide, it is found that an extension or a flow guide  200  of the present invention can provide a reduction in audible noise of as much as 2 to 3 decibels. 
     According to an embodiment of the present invention, the extension  200  is essentially made from a soft or elastic material that is characterized by good damping properties. As illustrated in  FIG. 2 , the extension  200  includes an elastic surface  204  that is designed to be exposed to fluid flow  220 . Depending on the shape and position of the elastic surface  204  relative to the fluid flow  220 , the fluid may flow alongside the elastic surface  204  or it may impinge on the elastic surface  204  at some angle. The elastic wall  205  absorbs any transfer of kinetic energy from the fluid flow  220  to the extension, and any remaining energy is translated into vibrations of the whole extension  200 . In some embodiments, the extension  200  is a, single mass of elastic material providing a sufficient thickness of elastic material for adequate dampening. 
     The extension  200  includes an elastic wall  205  in contact with an adjoining part  116  of the housing so that the interface  202  between the extension  200  and the adjoining part  116  of the housing is made up of unlike materials. The discrete interface  202  further hinders transfer of any residual kinetic energy in the extension  200  to the housing  110 . This eliminates the need for an additional damper to be inserted, for example, between the extension and the housing, and enables savings in inventory and manufacture. 
     Embodiments of the present invention can be implemented at low cost to the manufacturer. In one aspect, there are available many commercially available materials that can be used to form the extensions  200 . To name but a few examples, such materials may include elastomers, polyurethane, and butyls. The manufacturer is therefore not constrained to the use of expensive materials, but is able to select a material that best suits his budget for the degree of damping required. 
     In another aspect, the extension  200  can be easily formed during manufacture by a process that lends itself to automation, thereby providing the manufacturer with an avenue for improved yields at low cost. One preferred method  400  of forming the extension of  FIG. 3  is outlined below with the aid of the flowchart of  FIG. 4 , although it will be understood that there are other ways of making an extension  200  of the present invention. 
     An elastic polymer that is stable in the drive operating temperature range is selected to form the extension. One example of a suitable polymer is a polymer that is traditionally used to make form-in-place gaskets. The pre-polymer or a gel-like form the polymer is extruded onto an upturned cover  114  (step  410 ), following a path  208  determined by the desired shape of the extension. The gel-like material is then allowed to cure (step  420 ). Once cured, the polymer adheres to the cover. In other words, the extension is securely attached to the cover even as it is formed. An extension  200 , specifically a flow guide, is thereby formed from the deposited polymer itself. The cover with the attached flow guide can then be used for assembly with the other parts of the disc drive. 
     Other features can also be incorporated into an extension or flow guide  200  by this method. For example, if it is desired that the surface  204  presented by the extension  200  to direct the fluid flow not deviate from the general direction of the impinging fluid flow  220  by more than 45 degrees, this maximum angle of attack  212  can be set by appropriate shaping of the elastic surface  204 , which in turn can be controlled by controlling the relative motion of the extrusion and the supporting housing member, or the shape of the extrusion. It would be relatively easy for a manufacturer to use the same equipment to make extensions of different shapes and sizes to suit different applications simply by changing parameters of the extrusion process, without having to commission new molds or machine components. This method of manufacture is thus significantly more flexible and better suited for low cost manufacture of rapidly changing product lines. 
     It can further be appreciated that this method,  400  allows one to produce an extension  200  that is in such close abutment  210  with an adjacent structure  520  that there is no gap between the extension and the adjacent structures.  FIG. 5  shows an example where the extension  200  is a flow guide that is incorporated with the cover  114  of a disc drive. The flow guide is designed to facilitate maximum fluid flow through the filter  500 . In this example, the filter  500  is held in place by filter supports  510 ,  520 . There is preferably no leakage of fluid between the extension  200  and the filter support  520 . This can be achieved by applying the gel-like material directly to both the filter support  520  and the cover  114 . The adhesive nature of the gel-like material will ensure that the extension  200  mates well with both the cover  114  and the filter support  520 , leaving no gaps between the components. In similar fashion, embodiments of the present invention can be applied to provide the required physical barrier in a variety of situations. 
     Although the above example involves extruding an extension directly on part of a housing, the present invention does not preclude the use of pre-formed parts. For example, the extension of  FIG. 6  may be molded in a separate process and subsequently attached to part  116  of the housing using an epoxy adhesive. Being wholly made of one or more elastic materials, the extension  200  provides effective damping of vibrations superior to extensions that are made of a hard material. This is because the amount of damping provided by a thin layer of epoxy between a hard extension and the housing is expected to provide comparatively less damping of such flow induced vibrations. 
     In the above examples, the extension  200  is shown as a solid piece of a soft or elastic material. Alternative embodiments contemplated include extensions  200  that are substantially but not wholly made of some elastic material, while providing one or more elastic surfaces  204  for directing fluid flow  220 .  FIG. 7  illustrates a possible configuration in which the extension  200  includes an inelastic part  206  for supporting a desired shape of the elastic surfaces  204 .  FIG. 7  also illustrates alternate embodiments in which the extension  200  includes one or more pockets of air or other materials  206  within one or more elastic walls so as to provide a desired overall elasticity for the desired dampening effect. The interface  202  between the extension  200  and the adjoining housing portion  116  is defined by two dissimilar materials, one of which is sufficiently elastic to absorb any flow-induced vibrations so that such vibrations are not transferred to the adjoining housing portion  116 . 
     Alternatively described, embodiments of the present invention include a housing component (such as  112 ,  114 ) that has a structural member (such as  114 ,  116 ), as well as an extension (such as  200 ) which projects from the structural member, with the extension having an elastic wall (such as  205 ). 
     In some embodiments, it can be said that the elastic wall (such as  205 ) includes an elastic surface (such as  204 ) that has at least one part that faces away from the structural member (such as  114 ,  116 ). Part of the elastic surface (such as  204 ) may be in contact with the structural member (such as  114 ,  116 ). Further, there may be an interface (such as  202 ) of unlike materials between the extension (such as  200 ) and the structural member (such as  114 ,  116 ). 
     The extension (such as  200 ) may essentially consist of an elastic material. The extension (such as  200 ) may be directly adhered to the structural member (such as  114 ,  116 ), or an adhesive may be used to join the extension (such as  200 ) to the structural member (such as  114 ,  116 ). 
     Embodiments of the present invention may further include a housing (such as  110 ) for an electronic device (such as  100 ). The housing (such as  110 ) includes the aforementioned housing component (such as  112 ,  114 ) in assembly with at least one other housing element (such as  112 ,  114 ) to form an interior into which the extension (such as  200 ) projects. 
     Embodiments of the present invention may also include a data storage device (such as  100 ) that has a disc stack assembly (such as  124 ) rotatably mounted to the aforementioned housing (such as  100 ) such that when the disc stack assembly is in rotation, fluid flow (such as  220 ) generated in the interior of the housing is directed by the extension (such as  200 ). The data storage device (such as  100 ) may further include a filtration unit (such as  500 ) in the interior of the housing, with the extension (such as  200 ) configured to direct fluid flow (such as  220 ) to or from the filtration unit. 
     According to other embodiments of the present invention, there is provided a method (such as  400 ) of forming the aforementioned housing component (such as  112 ,  114 ). The method (such as  400 ) includes steps of (a) (such as  410 ) applying a gel-like material to the structural member, and (b) (such as  420 ) allowing the gel-like material to cure and form the extension. The applying step (a) (such as  410 ) may involve extruding the gel-like material onto the structural member. Alternatively, the method (such as  400 ) of forming the aforementioned housing component (such as  112 ,  114 ) includes steps of (a) providing a molded elastic extension (such as  200 ) and (b) attaching the extension (such as  200 ) to the structural member (such as  114 ,  116 ). 
     It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the shape, size and function of the extension  200  may vary depending on the particular application for the consumer product without departing from the scope and spirit of the present invention. In addition, although the embodiments described herein are directed to a disc drive or a data storage device, it will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other electronic devices without departing from the scope and spirit of the present invention.