Abstract:
A sealing mechanism for a customer replaceable unit (CRU) within a computer system is provided. The sealing mechanism comprises a faceplate for the CRU, wherein insertion and extraction latches are recessed into a trench within that faceplate. The backside of the faceplate has a protruding rim around the perimeter. The rim engages a groove in the subsystem enclosure, which surrounds the aperture that the CRU engages. Since the faceplate incorporates a perimeter ridge and a trench structure, the interacting groove follows the contour of the trench. Thus the rim and groove both trace the faceplate trench around the faceplate. The groove in the subsystem enclosure has an entrenched section at both ends of the receptacle perimeter that accommodate sections of the faceplate rim that trace the trench in the faceplate. A compliant seal material seated is in the groove of the chassis-mating surface, wherein the seal material follows the contours of the chassis-mating surface and ensures electrical contact between the chassis-mating surface and protruding faceplate rim.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention is directed generally toward storage system enclosures and customer replaceable units. 
     2. Description of the Related Art 
     Controller modules and drive trays are modular computer components that are usually connected together in a customer-specified configuration to produce storage systems. Controller modules function as the interface between a host system and the drive tray array. The drive trays often use enclosure service modules (ESMs) as the interconnection to the drives contained within a drive tray. The ESMs also perform diagnostic monitor functions for the drive array. 
     ESMs may take the form of customer replaceable units (CRUs), which are incorporated into subsystems in a storage system. This provides the customer freedom and direct control over the configuration and maintenance of subsystems. The CRUs contain insertion/extraction levers or latches that are used to install and remove CRUs from a storage system chassis. 
     Currently, the insertion/extraction levers and latches are mounted on the faceplate of CRUs and project forward from the front surface of the faceplate. Industrial designers and mechanical engineers must define features that hide this forward projection of the latch mechanisms. Imposing this type of restriction on industrial designers may interfere with their ability to achieve successful designs consistent with expressing the power and capabilities of the new subsystems. 
     Therefore, it would be desirable to alter the shape of the faceplate for controller support modules so that the packaging of these modules becomes more compact and the industrial designer has more freedom in development of expressive designs. 
     SUMMARY OF THE INVENTION 
     The present invention provides a sealing mechanism for a customer replaceable unit (CRU) within a computer system. The sealing mechanism comprises a faceplate for the CRU, wherein insertion and extraction latches are recessed into a trench within that faceplate. The backside of the faceplate has a protruding rim around the perimeter. The rim engages a groove in the subsystem enclosure, which surrounds the aperture that the CRU engages. Since the faceplate incorporates a perimeter ridge and a trench structure, the interacting groove follows the contour of the trench. Thus the rim and groove both trace the faceplate trench around the faceplate. The groove in the subsystem enclosure has an entrenched section at both ends of the receptacle perimeter that accommodate sections of the faceplate rim that trace the trench in the faceplate. A compliant seal material seated is in the groove of the chassis-mating surface, wherein the seal material follows the contours of the chassis-mating surface and ensures electrical contact between the chassis-mating surface and protruding faceplate rim. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1A depicts a top view perspective diagram illustrating a Customer Replaceable Unit (CRU) in accordance with the prior art; 
     FIG. 1B depicts a bottom view perspective diagram illustrating the prior art CRU; 
     FIG. 2A depicts a top view perspective diagram illustrating a CRU receptacle in accordance with the prior art; 
     FIG. 2B depicts a close up of one of the corners of receptacle in FIG. 2A; 
     FIG. 3 depicts an exploded view diagram illustrating the interaction of components in accordance with the prior art; 
     FIG. 4 depicts a cross section schematic diagram illustrating the CRU fully inserted into the receptacle in accordance with the prior art; 
     FIG. 5A depicts a schematic diagram illustrating a close up view of how the CRU faceplate mates with the receptacle and seal; 
     FIG. 5B depicts a schematic diagram illustrating a close up view of the faceplate rim, seal, and recessed surface fully assembled; 
     FIG. 6 depicts a perspective view diagram illustrating a CRU with an entrenched latch in accordance with the present invention; 
     FIG. 7 depicts a perspective view diagram illustrating is a CRU receptacle with a modified chassis-mating surface in accordance with the present invention; 
     FIG. 8 depicts an exploded view diagram illustrating the CRU being inserted into the CRU receptacle in accordance with the present invention; 
     FIG. 9A depict a side view diagram illustrating the CRU partially inserted into the CRU receptacle in accordance with the present invention; and 
     FIG. 9B depicts the same side view as FIG. 9A, showing the articulation of the latch. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1A, a top view perspective diagram illustrating a Customer Replaceable Unit (CRU) is depicted in accordance with the prior art. The faceplate  101  sits on top of the body of the CRU  100  like a flange. On the opposite side of the faceplate/flange are the sealing features for the CRU designed for electromagnetic interference (EMI) suppression. 
     FIG. 1B depicts a bottom view perspective diagram illustrating the prior art CRU  100 . The rim  110  on the back of the faceplate  101  is visible in this view. This rim  110  presses against the included electrically conductive seal (described below) that will be fastened to the inside rim of the CRU receptacle. 
     Referring to FIG. 2A a top view perspective diagram illustrating a CRU receptacle is depicted in accordance with the prior art. The receptacle  200  depicted in FIG. 2A really represents a hole in a chassis, without the chassis actually being illustrated. A recessed groove  201  for an electromagnetic compatibility (EMC) seal is built into the front face of the object. 
     FIG. 2B depicts a close up of one of the comers of receptacle  200  in FIG.  2 A. This close up view allows for better illustration of the features of the seal area. It shows the wall  202 , the recessed surface  201  and the inner lip  203 . 
     Referring to FIG. 3, an exploded view diagram illustrating the interaction of components is depicted in accordance with the prior art. This view clearly shows how the CRU  100  fits into the CRU receptacle  200 . The seal  300  separates the receptacle  200  and the CRU  100  that goes into it. When fully assembled, the seal  300  would not be visible because it is buried in the contact region  201  and should be pinched in the assembly. In the present example, the seal  300  is about 0.030 inches thick and is designed to fit into the recessed area  201  of the receptacle  200 . Depending on the geometric design and the degree of wipe, collapse or compression necessary, the seal  300  may be as thick as 0.050-0.060 inches. 
     The seal (gasket)  300  may be made of silver-bearing or graphite-bearing elastomers. These elastomers contain metallic (often silver) plated glass spheres or conductive flakes that are mixed with the uncured elastomers and function as conductive filler materials within the elastomers. The seal  300  may be robotically applied, die cut or extruded. The seal  300  is usually either directly applied as an auto-adhesive material or attached by a conductive adhesive material. Conventionally, it is preferable that this material be permanently affixed to the structure and not capable of independent motion. The purpose of this material is to act as a kind of gap filling conductive caulk or gasket. It forms a good electrical connection between articulating components and blocks the emission of radiated electrical noise. It also functions as the connection path for chassis ground or safety ground between interrelated components. 
     FIG. 4 depicts a cross section schematic diagram illustrating the CRU  100  fully inserted into the receptacle  200  in accordance with the prior art. The CRU  100  is properly and symmetrically placed within the receptacle  200  provided for it in the chassis. FIG. 4 shows two latches  401  and  402  attached to the CRU faceplate  101 . The latches  401 - 402  stand about 0.74 inches above the front surface. This poses an obstacle for industrial designers. 
     FIG. 4 also shows a schematic connector  410 , which might be, e.g., the power supply connector. The connector  410  cannot be counted on for lateral support since it floats. This connector  410  must float because it is designed as a “blind mating connector”. In addition, it cannot control the depth of the CRU insertion since it is functional over a range of insertion depths. 
     FIGS. 5A and 5B depict schematic diagrams illustrating a close up view of how the CRU faceplate  101  mates with the receptacle  200  and seal  300 . The recess  201  is die cast into the periphery of the chassis-mating surface of the receptacle  200 . The resilient/compliant electrical seal  300  rests within the recess  201 . The faceplate rim  110  is tongue and grooved into the recessed surface  201  with the conductive seal  300  in between, as illustrated in FIG.  5 B. 
     In theory, retention forces deforn the seal  300  circumferentially. The seal  300  is not extremely thick, depths of 0.020-0.030 inches are probably to be expected. However, as stated above, the seal  300  may be as thick as 0.050-0.060 inches. A certain level of compression must be reached to establish reliable continuity. 
     Referring now to FIG. 6, a perspective view diagram illustrating a CRU with an entrenched latch is depicted in accordance with the present invention. The present invention involves recessing the latches  401  and  402  into a wedge shaped “trench”  610  across the faceplate  601  of the CRU  600 . The power supply within this CRU  600  is laid out with short components on the edge, so as not to interfere. For purposes of illustration, the same type of latches  401  and  402  in the prior art can be used with the present invention. However, the latches used may vary from those shown in the figures. The trench shape of the CRU faceplate  601  requires the contour of the seal to change as well. Since these are die cast parts such a change can be fairly easily accomplished. The seal may be robotically installed, so it makes little difference if it is in a single plane (as in the prior art) or has been convoluted into three dimensions (as required of the present invention). The change results in a “wedge” feature  620  being designed into the sides of the CRU  600 . 
     The trench  610  may be split into two parts, each with its own latch. Such an approach would provide an “island” between the latches  401  and  402  on which to mount indicators. This face would be perforated for airflow. These structures would be designed to accommodate that airflow and to not interfere with module cooling. The pedestals that these latches  401 - 402  mount on may be cast-in features. 
     There has been some discussion in the prior art about such a recess acting as a radiating horn. An example is the divider in the class 2625 drive tray. Similar behavior is unlikely with the present invention. The 2625 drive tray has a deep trench surrounded by high data rate disk drives. Its divider is a piece of sheet metal poorly connected to the chassis electrically. By contrast, the present invention uses a shallow trench near a power supply operating at a frequency of about 100 KHz. Instead of a having a metal divider, the trench is integral to the faceplate. 
     The trench  610  allows the latches to insert deeper into the CRU receptacle and provides the designer with the opportunity to accomplish the latching function forward of the seal with integral engagement features. The wedge shaped seal structure  620  provides alignment and positioning for the CRU. Entrenching the latches  401 - 402  reduces the level of interference between the latches  401 - 402  and the decorative faceplate  601 . This allows the industrial designer the maximum latitude in developing the functional image without fighting with the underlying structure, unlike the prior art. 
     Referring now to FIG. 7, a perspective view diagram illustrating is a CRU receptacle with a modified chassis-mating surface is depicted in accordance with the present invention. As can be seen clearly in the figure, the recess  701  that holds the EMC seal has a section with a wedged trench shape. The recess  701  is designed this way to accommodate the latch wedge  620  when the CRU  600  is inserted into the receptacle  700 . The EMC seal is more convoluted than the seal  300  in the prior art, but the concept remains the same. It rides in the recessed track  710  similar to the planar version of the seal and is compressed in the same way by the same amount. The present invention uses the same underlying tongue-in-groove chassis mating as illustrated in FIGS. 5A and 5B. 
     FIG. 8 depicts an exploded view diagram illustrating the CRU  600  being inserted into the CRU receptacle  700  in accordance with the present invention. This view illustrates the function of the wedge shaped alignment and positioning structure  620 . Also depicted is the modified EMC seal  800 . As with the prior art, when fully assembled, the seal  800  would not be visible because it is buried in the contact region  701 , usually firmly attached to the chassis. 
     Embedding the articulating interaction surfaces deeper into the subsystem provides structural advantages. The attachment strategy is more robust. This creates stronger more resilient retention for installed CRUs. On the other hand, placing the latching mechanism high and protruding above the faceplate (as in the prior art) makes it necessary to extend interacting structures up to the level of the latch. This causes the latching mechanisms to act as cantilevered beams, otherwise unsupported and somewhat flimsy. By placing the CRU deeper into the enclosure, the enclosure itself provides substantial added resiliency and eliminates the fragility associated with the extended latching tabs. 
     Furthermore, there are potential emissions advantages to burying the engagement surfaces deeper inside the enclosure. These advantages come about due to a kind of electrical/structural analogy. The latch is a metal-to-metal contact point. All other contact points in the assembly have intermediary gasket interfaces. This makes the latch contact at the front of the enclosure unique. The less “extended” this contact point is, the better it will provide safety (chassis) ground continuity. The invention encapsulates the emission gap from the metal-to-metal latch contact point and moves it into a more protected region of the structure. 
     As a matter of convenience, the latching structures are less prone to damage if they are embedded more deeply. One specific type of latch that may be used has two small “teeth” that engage some other structure to generate the contact forces necessary to compress the gasket. If those engagement holes in the structure are surrounded by the body metal of the enclosure, they will be less likely to rip out and tear loose than if they are cut into extended fastener tabs that protrude from the enclosure leading edges. 
     FIGS. 9A and 9B depict side view diagrams illustrating the CRU  600  partially inserted into the CRU receptacle  700  in accordance with the present invention. This side view of the CRU  600  being inserted into the CRU receptacle  700  shows how the flange  901  has been convoluted into the third dimension. The edge fin  902  as shown here compresses the seal  800  (not shown) in the same fashion as the similar edge fin  110  does in the planar version. FIG. 9B shows one of the latches  401  articulating as it would during normal insertion and extraction operations. 
     The enclosure and structures may be constructed of various assemblies of sheet metal, extrusions and dies castings. Materials may include common sheet metals, various casting alloys of aluminum, zinc and magnesium. For example, assemblies might include die cast faceplates on aluminum CRU bodies. The gasket material might include, e.g., metallic wrapped foams, and foil constructions of several types may be appropriate. Conductivity and conformation to existing geometry are important. 
     The description of the preferred embodiment of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention the practical application to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.