Abstract:
Floor care devices having an elongated handle or body portion for control thereof are provided with mid-level handles for facilitating manipulation of the devices in certain conditions, for storing power cords, for hanging and storing the floor care device and the like. The mid-level handle may fold from a retracted position adjacent the elongated handle or body portion to an extended position. A retainer is provided to maintain the handle in its retracted and extended positions.

Description:
TECHNICAL FIELD 
     The present invention relates to mid-level handles suitable for use with floor care devices such as, for example, an upright vacuum cleaner. 
     BACKGROUND OF THE INVENTION 
     Vacuum cleaners and other power floor care devices, such as floor buffers, carpet shampooers, steam cleaners, power sweepers and buffers are common and well-established appliances for commercial and residential floor care. Such devices commonly include a power cord that attaches to the grip at the end of the handle at which point a user holds the device to use it. 
     A wide variety of floor care device configurations, in general, and vacuum cleaner configurations, in particular, are available to suit the needs of a particular application or user, including upright vacuums, canister models, and hand-held models. 
     Vacuum cleaners, such as upright vacuums, remove dirt from a carpet by creating a suction strong enough to draw the dirt particles and other contaminants from a section of the carpet up into the vacuum cleaner where the dirty air is passed through a vacuum bag in which the entrained dirt is captured. To increase the efficiency of this process, a base portion of the vacuum cleaner often has a roller brush for agitating dirt from the carpet as it is being vacuumed. 
     Inside the vacuum cleaner, a conduit transfers the dirty air from the base of the vacuum cleaner to the vacuum bag. The dirty air conduit runs up a handle assembly or, in cases where the dirty air conduit is rigid, the dirty air conduit can itself function as a portion of the handle. At the end of the dirty air conduit opposite the floor there is a duct from which the dirty air exits from the dirty air conduit. The vacuum bag is attached to the dirty air outlet nozzle and receives and filters the dirty air which it receives from the duct. 
     The vacuum bag has a bag opening that fits closely over the dirty air outlet duct. The vacuum bag is otherwise a completely closed bag that is made from a porous material, such as porous paper, that allows air to flow through it, but which is too fine for most dirt particles to pass through. As dirty air passes through the vacuum bag, the air is forced through the porous material and the dirt is trapped in the bag. The bag thus collects the dirt from the dirty air and, more importantly, from the floor. Because the material of the vacuum bag is often fragile and can get very dusty, the vacuum bag is commonly held within a protective outer bag. 
     One common vacuum bag design incorporates a reinforced area, known as a collar, surrounding the bag opening. The collar is usually a square or rectangular piece of thin cardboard. To install the vacuum bag, the user holds the collar by one or more edges, and forces the bag opening over the dirty air outlet nozzle. The collar can be designed with an elastic seal extending inward from the circumference of the bag opening to further seal the gap between the dirty air outlet duct and the bag opening. 
     As shown in FIG. 1, a prior-art upright vacuum cleaner  20  may comprise a head  22 , which includes a motor and fan which cooperate to create suction at floor level. Air sucked into the head  22  by the fan is blown into the dirty air conduit  24  that forms a part of the handle  26  of the vacuum cleaner. Upon reaching the end of the dirty air conduit  24 , the air stream with its entrained particulates (the dirty air) is directed through the dirty air exhaust duct  28  into a flexible vacuum cleaner bag  30 , which is mounted in a generally air-tight manner to the exhaust duct  28 . 
     FIG. 1 also provides an exploded view of a prior-art dirty air exhaust duct  28  docking system  32  for receiving air from a dirty air conduit and diverting it laterally into a vacuum cleaner bag  30 . The docking system  32  comprises a yoke  34  which may be mounted about the periphery of the exhaust duct  28 . The exhaust duct  28  includes a flange (not shown) about its periphery for retaining the yoke  34  in place. 
     The yoke  34  is hinged to a bag dock  36  into which the mounting collar  38  of the bag  30  may be inserted. The yoke  34  and bag dock  36  are made of a somewhat rigid plastic material and snap together when they are pivoted relative to one another from the open position (shown in FIG. 1) to a closed position. 
     A mounting collar  38  is mounted on the vacuum cleaner bag  30 . This collar is configured to slide into guides on the bag dock  36 . The mounting collar  38  includes a flexible seal  40  which covers a portion of the aperture  42  which extends through the mounting collar  38  and opens into the interior of the bag  30 . The collar  38  is made of three layers of cardboard or the like, the middle layer being slidable with respect to the front and back layers. The tab  44  forms a lower portion of the middle layer of the collar  44 , and may be pulled downward relative to the collar  38  to slide the middle layer to a position where the aperture  42  is covered. In this position, the particulate material in the vacuum cleaner bag  30  is sealed therein. 
     When the bag dock  36  is pivoted to its closed position relative to the yoke  34 , the aperture  42  and the seal  40  are positioned about the periphery of the exhaust duct  28  in sealing engagement therewith. The exhaust duct  28  is then in communication with the interior of the vacuum cleaner bag. 
     In prior art upright vacuum cleaners, such as that shown in FIG. 1, the dirty air conduit  24  generally is closed off adjacent to the dirty air exhaust duct  28  to which the vacuum bag is attached. This exhaust duct generally extends at right angles from the upper end of the dirty air conduit a sufficient distance so that the vacuum cleaner bag, and, as applicable, an outer bag made of cloth or the like, can be mounted on it, with the open mouth of the duct exhausting the dirty air into the bag. 
     While such a vacuum cleaner functions adequately, there remain certain problems with the design. A common complaint relating to this and other vacuum cleaners is that they are very noisy. One component of this noise is believed to be caused by turbulence generated as the rapidly-flowing dirty air reaches the upper, sealed end of the dirty air conduit and flows laterally out the dirty air duct. 
     Another difficulty of the present design is rebounding of larger, heavier objects, such as coins, after impact with the sealed end of the conduit. Since the sealed end of the dirty air conduit is generally perpendicular to the direction of flow of the air up the conduit, such objects may bounce back down the conduit (against the air flow) only to be blown back into the end of the conduit and rebound again. Eventually, the object may be blown into the bag, ending this cycle of rebounding, but the noise of the impacts of such objects into the sealed end of the conduit can be disconcerting to users of the vacuum cleaner. 
     The design also results in loss of vacuum cleaner efficiency. The abrupt change in airflow direction and the turbulence generated in the course of such change of direction result in greater backpressure in the conduit, which results in a reduction in cleaning ability of the vacuum cleaner. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a mid-level handle for floor care devices, and is applicable to a variety of such devices, including upright vacuum cleaners. The mid-level handle may be positionable between extended and retracted positions. In the extended position, the handle may permit easier gripping and manipulating of the device at levels elevated above the level at which the operator is standing, may be adapted provide for convenient storage of the power cord, and may provide a convenient means for carrying and hanging the floor care device. The handle may be retractable to permit the handle of the device to be lowered for access under low-clearance obstacles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial exploded view of an upright vacuum cleaner in accordance with the prior art. 
     FIG. 2 is a side elevation of an upright vacuum cleaner having a dirty air exhaust duct according to one embodiment of the present invention. 
     FIG. 3 is an exploded isometric view of the upper portion of the upright vacuum cleaner of FIG.  2 . 
     FIG. 4 is an exploded isometric view of a dirty air exhaust duct according to one embodiment of the present invention with associated components. 
     FIG. 5 is an isometric view of a vacuum cleaner according to one embodiment with the power cord stowed on the handles thereof. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to a mid-level handle for a floor care device such as an upright vacuum cleaner. As the principles and benefits of the present invention can be described in connection with an upright vacuum cleaner in a manner that will enable those skilled in the art to apply it to other floor care devices, the invention will be explained in connection with embodiments involving an upright vacuum cleaner. From such embodiments, those skilled in the art will easily perceive ways in which the invention may be applied to floor care devices such as floor buffers, carpet shampooers, steam cleaners, power sweepers and buffers. 
     FIG. 2 shows a vacuum cleaner  100  according to one embodiment of the invention. In like manner to the prior art vacuum cleaner  20  of FIG. 1, the present vacuum cleaner  100  includes a head  102  that contains the vacuum motor and fan, a rotary brush, and other such components (not shown) that are known in the art. An elongated handle  103  is pivotably attached to the head for maneuvering and controlling the head. 
     The purpose of the head  102  and its components is to provide suction at the level of the floor  104 , which may be a wood floor, or may be covered with carpet, throw rugs, tile, linoleum or other floor coverings. As is well known, the air entrains particulates such as dirt, sand, lint, crumbs and other food particles, and other materials that may be found on a floor, 
     The particulate-laden air (dirty air) is exhausted from the head  102  via an exhaust conduit  106 , which is pivotably mounted to the head to permit rotation through about 90 degrees from a generally vertical orientation to a generally horizontal orientation as indicated by the arrow  108 . The particulate-laden air is transmitted upward along a dirty air conduit  110  to a dirty air exhaust duct  112 . The dirty air conduit  110  of the present embodiment may be made of any of a variety of materials, such as steel or aluminum tubing, but should be sufficiently stiff to serve both as a conduit and as a portion of the elongated handle  103  of the vacuum cleaner  100 . 
     A clamp  109  is mounted on the exhaust conduit  106  of the vacuum cleaner  100  by known means such as screws or other fasteners. A spring clip  111  is mounted on the clamp and is adapted to clip into a slot in the bag clamp  113 . The bag clamp  113  is adapted to grip the bottom of a flexible bag case  136 , when the two halves thereof are assembled. 
     Referring to FIGS. 2 and 3, in which like elements have like numbering, the dirty air conduit  110  is maintained in engagement with the exhaust conduit  106  as follows. A slot  114  in the lower end of the dirty air conduit  110  is adapted to receive and be substantially filled by a tab (not shown) on the interior wall of the exhaust conduit  106 . The tab and slot prevent the exhaust conduit  106  and dirty air conduit  110  from rotating relative to one another. 
     An annular shoulder may be provided in the exhaust conduit  106  to receive the bottom end  116  of the dirty air conduit  110 . Such shoulder preferably has a width approximately equal to that of the wall thickness of the dirty air conduit  110 . The dirty air conduit is held in place by a collar  118  and elastomeric ring  120 . The collar  118  and ring  120  are adapted to slide onto the dirty air conduit  110  and the collar  118  is configured to receive the ring  120  therein. 
     The collar  118  threadedly engages the upper end of the exhaust conduit  106  and screws down onto it. The elastomeric ring  120  is thereby compressed between a shoulder internal to the collar  118  and the upper end of the exhaust conduit  106 . The compression of the ring forces the ring  120  to expand into tight engagement with the adjacent surface of the dirty air conduit  110 , which retains the dirty air conduit  110  against axial movement out of engagement with the exhaust conduit  106  in normal use. 
     The lower end  122  of the exhaust duct  112  includes a threaded region  124  and can be mounted to the dirty air conduit  110  in like manner to the mounting of the dirty air conduit  110  to the exhaust conduit  106 . A tab (not shown) on the interior of the exhaust duct  112  is received in a slot  126  in the upper end of the dirty air conduit  110 , substantially filling the slot  126 . A collar  128  and elastomeric ring  130  are slid over the upper end  132  of the dirty air conduit  110 , and the collar is screwed onto the lower end  122  of the exhaust duct  112 , compressing the ring  130  and causing it to frictionally engage the adjacent wall of the dirty air conduit  110 . Of course, in another embodiment the dirty air conduit  110  and exhaust duct  112  could be joined in any of a variety of known manners, such as by using clamps, flanges and fasteners or bonding of one to the other. The dirty air conduit  110  and the exhaust duct  112  could also be formed as a single unit if desired. 
     As best shown in FIGS. 3 and 4, the upper end  132  of the dirty air conduit  110  (FIG. 3) is configured to abut a shoulder  134  (FIG. 4) which extends around the interior surface of the exhaust duct  112 . The shoulder may preferably have a width equal to the wall thickness of the dirty air conduit  132  to provide the airflow in the conduit with a smooth transition from the dirty air conduit  110  to the exhaust duct  112  to avoid generation of turbulence at the transition point. 
     As shown in FIGS. 2 and 3, the vacuum cleaner  100  is provided with a bag case  136  into which the dirty air may be exhausted from the dirty air exhaust duct  112 . The bag case  136  may be made of a flexible material that is resistant to wearing and ripping, and that is either air pervious or includes vents to allow the escape of air. In another embodiment, the bag case may be a vented, rigid case made of plastic or other such material. The bag case  136  is adapted to be mounted over the mouth section  138  of the dirty air duct  112 . The bag case  136  may be openable with a zipper or other such means, for insertion and removal of vacuum cleaner bags, such as the prior art bag  30 , which may be made of a fibrous material such as porous paper. The bag case  136  is adapted to contain the bag without unduly constricting it. 
     After the bag case  136  has been positioned over the mouth  138  of the duct  112 , a bag case support  140  (for flexible bag cases  136 ) and bag docking system  142  are inserted in the bag and positioned over the mouth  138  of the exhaust duct  112 . The yoke  144  engages the periphery of the mouth  138  firmly to maintain the docking system (and the bag case  136  and bag case support  140 ) in place. A mounting collar of a vacuum cleaner bag (not shown) may be inserted into the bag dock  146 , and the bag dock  146  may be pivoted relative to the yoke  144  to position the vacuum cleaner bag in sealing engagement with the mouth  138  of the exhaust duct  112 , as described in connection with the prior art vacuum cleaner of FIG.  1 . The bag case  136  may then be closed. 
     The upper end  150  of the exhaust duct  112  includes a threaded section  152 . A plurality of vertical slots  154  extend to the upper end of the exhaust duct  112 . The threaded section  152  and the slots  154  cooperate with a collar  156  to form a collet-like connector for receiving and gripping an upper handle segment  158 . 
     A two-piece handle (or grip)  160  for permitting a user to grip the end of the elongated handle  103  may be mounted to the upper end of the upper handle section  158  by fasteners such as screws. The two halves of the handle  160  may advantageously be made of a thermoplastic material, and may be bonded together by known methods such as vibratory welding or use of adhesives. 
     A switch may be provided in the handle  160  for controlling the flow of electricity to the motor in the head  102  of the vacuum cleaner  100 . For this purpose, a first power cord  162  adapted to be plugged into a wall outlet may be routed through the handle  160  to the switch, and a second power cord  164  may extend from the switch, through the handle  160  and into the head  102  of the vacuum cleaner  100  to power the vacuum cleaner motor. The lower tip of the handle  161  may be angled upward and outward from the longitudinal axis of the upper handle section  158 , which makes it able to retain a plurality of loops of the power cord  162  thereon, as will be explained below. Alternatively, a hook could be mounted on the handle  160  or handle section  158  to receive loops of a power cord  162 . 
     Referring to FIGS. 2,  3  and  4 , a handle mount  166  extends from the side of the exhaust duct  112  opposite the mouth  138 . The handle mount  166  defines a hemicylindrical channel for receiving a cylindrical portion  168  of the mid-level handle  170 . A handle support clamp  172  adapted to fit around the exhaust duct  112  below the mouth  138  includes a handle mount  174  which defines a hemicylindrical channel corresponding to that defined by the handle mount  166  of the exhaust duct  112 . The clamp  172  is secured in position by a fastener, such as a screw, which extends through an aperture  176  therein. The handle mount  174  is divided into two parts by a slot  178 . A screw inserted in the aperture  176  may thus extend through both halves of the handle mount  174 . When the screw is tightened (e.g., by screwing it into a nut on the opposite side of the handle mount  174  from that on which the head of the screw is located), the opposed faces of the slot  178  may be drawn together, drawing the clamp  172  tightly about the exterior of the exhaust duct  112 . 
     The handle mount  174  of the clamp  172  is formed such that, when the clamp  172  is mounted on the exhaust duct  112 , it forms a cylindrical channel with the handle mount  166  of the exhaust duct  112  to receive the cylindrical portion  168  of the mid-level handle  170 . 
     As best shown in FIG. 4, a slot  180  is provided in the handle mount  166 . The slot is configured to receive a leaf spring  182 , which bears on a plurality of cam surfaces  184  of the handle  170  when the handle is positioned in the cylindrical channel formed by the handle mounts  166 ,  174 . The shoulders  186  adjacent the cam surfaces  184  prevent the leaf spring from moving out of the channel. The leaf spring  182  and cam surfaces  184  cooperate to act as a retainer to maintain the handle either in the extended, generally-horizontal position, in which it extends outward from the exhaust duct  112 , as shown in FIG. 2, to a retracted, generally vertical position (not shown) in which the handle  170  is pivoted through an angle  188  downward and against the exhaust duct  112 . 
     Stops  185  extend from the cylindrical portion  168  of the mid-level handle  170 . When the handle is pivoted to its extended position, the stops  185  engage shoulders  187  on the clamp  172 , preventing the handle from pivoting upward beyond the generally horizontal position. 
     As shown in FIG. 4, the handle  170  includes a broad grip section  190 , which is sufficiently large to allow an operator to insert his or her hand therein. This broad grip section  190  is attached to the cylindrical portion  168  by a narrow neck section  192 . The difference in width between the neck section  192  and grip section  190  is sufficient that the handle  170 , when in its extended position, may receive a plurality of loops of the power cord  162 . 
     The mid-level handle  170  may advantageously be positioned in, and maintain its position in, the extended and retracted positions. First, as the greatest portion of the mass of the vacuum cleaner  100  is concentrated in the head  102 , the mid-level handle  170  is located above the center of mass of the vacuum cleaner  100 . Thus, in the extended position, the mid-level handle  170  may be used to carry the vacuum cleaner  100 , or may be positioned over a hook on a wall or cart to permit convenient storage or transportation thereof. 
     The mid-level handle  170  is also useful in its extended position when cleaning surfaces that are located above the level at which a user is standing. By gripping the handle  160  in one hand and the mid-level handle  170  in the other, a user may conveniently manipulate the vacuum cleaner  100  on stairs above the level at which the user is standing and in other locations where manipulating the floor care device solely by the handle  160  may be inconvenient. 
     Finally, as shown in FIG. 5, multiple loops of the power cord  162  may be wrapped about the neck  192  of the extended mid-level handle  170  and around the handle  160  for storage purposes. The broad loop of the grip section  190  of the handle  170  prevents the cord  162  from slipping off the mid-level handle  170 , and the upwardly-oriented tip  161  of the handle  160  likewise serves as a cord retainer to retain the loops of cord  162  on the handle  160 . Of course, in lieu of wrapping the cord  162  about the handle  160 , a hook could be provided at a position adjacent to the handle  160  to serve as an upper cord retainer to receive the cord  162 . 
     The extended position of the handle provides some drawbacks, however. When vacuuming under furniture, the user may wish to pivot the handle  160  relative to the head  102  of the vacuum cleaner through an angle  108  to a position near to the floor  104 . Having the handle extending outward from the back of the exhaust duct  112  may impair the ability of the user to lower the elongated handle  103  as close to the floor as may be desired. Thus, the ability of the handle  170  of the present embodiment of the invention to be positioned in its retracted position and maintained in that position by the cam spring  182  and cam surfaces  184  will facilitate cleaning in such circumstances. 
     Similarly, when cleaning behind obstacles, such as low tables, a protruding handle may catch on the obstacles. Again, the ability of the mid-level handle  170  to be positioned and maintained in a retracted position may facilitate the cleaning process. 
     Of course, those skilled in the art will appreciate that the mid-level handle  170  may have any of a variety of configurations. For example, the handle may be formed in the shape of a “T.” The handle may also be affixed higher or lower on the elongated handle  103  of the device, for example, by using a clamp similar to the clamp  172  which, by itself, is capable of receiving the cylindrical portion  168  of the mid-level handle  170 . Such persons will also appreciate that other means may be provided for maintaining the handle in its extended and retracted positions, such as spring actuated catches, ball detents and the like. 
     The handle  170  of the present embodiment may advantageously be made of a thermoplastic, thermosetting or other material that has suitable rigidity and strength, and preferably is impact resistant. The handle may be formed by one or more known methods, such as injection molding, casting and machining. Preferably, the injection molding of a thermoplastic material is used. The handle may be molded in multiple pieces that may be bonded together by one or more known methods such as the use of vibratory welding, thermal bonding or solvent or adhesive bonding. 
     One of the problems of conventional vacuum cleaners that makes their use undesirable is the level of noise they generate. Although this noise is within safety limits for the operator and others who may be nearby, it is still desirable to limit the amount of noise made by vacuum cleaners. This is particularly the case where the vacuum cleaners may be used near others who may be sleeping, who may be ill and in need of rest, or who may have difficulty concentrating or conversing over the noise. 
     Another problem common to upright vacuum cleaners with dirty air conduits that terminate in an exhaust duct that exhausts the air at approximate right angles to the airflow up the conduit is the problem of rebounding of heavier objects entrained in the airstream as described above. As shown and explained in connection with FIGS. 3 and 4, the exhaust duct  112  according to one embodiment of the present invention addresses both of these problems. 
     The exhaust duct  112  has an inlet of generally circular cross-section at its lower end  122 . The mouth  138  of the exhaust duct  112 , by contrast, has a generally-oval shape. While prior art devices have tended to simply provide a wall such as the wall  194  across the duct to stop further airflow therealong, and provide an outlet of any desired configuration, such exhaust ducts may create turbulence that increases the noise level of the vacuum cleaner and allows for rebounding of heavier objects. The increased turbulence also increases the backpressure in the vacuum cleaner, reducing the suction power thereof. 
     In the device of the present embodiment, the transition from the upward low in line with the longitudinal axis of the dirty air conduit  110  to the flow of air out of the mouth  138  of the exhaust duct  112  is facilitated by the present invention. As discussed above, the shoulder  134  receives the end of the dirty air conduit  110  and provides a smooth transition for the airflow for the transition from the dirty air conduit  110  into the exhaust duct  112 . 
     The transition of airflow from vertical to horizontal flow (that is, from flow axial to the dirty air conduit  110  to flow at an approximate right angle thereto out the mouth  138  of the exhaust duct  112 ) is smoothed by the contoured upper and lower curving  196 ,  198  of the back and front walls  200 ,  204  of the interior of the exhaust duct  112 . This differs from prior art devices in which the transition is not smoothly contoured to facilitate the change in flow direction. The lower curving  198  of the front wall  204  of the exhaust duct  112  also is smoothly continuous to minimize turbulence generation during the transition in flow directions. 
     In the present embodiment, the mouth  138  of the exhaust duct  112  has a generally oval cross-sectional shape, which is different from the generally circular cross section of the lower end  122  of the exhaust duct  112 . To avoid generation of turbulence, the transition from one shape to the other is likewise smoothly contoured, unlike prior art devices that change abruptly or with sharp edges from one shape to another. 
     In order to prevent the airstream from impinging directly on the surface of the vacuum cleaner bag opposite to the mouth  138  of the exhaust duct, a deflector  206  may be provided at the upper periphery of the mouth  138  of the exhaust duct  112 . Again, the deflector  206  is smoothly contoured to avoid generation of excessive turbulence. 
     In the preset embodiment, the upper curving  196  extends from the rear interior wall portion  200  to a position  202  which is generally directly above the front wall portion  204 . Thus, a heavy object such as a coin entrained in the airstream of the dirty air conduit  110  is most likely to strike the upper curving wall section  196  of the exhaust duct  112 , which is in line with the airstream rising up the lower section of the exhaust duct  112 , and be deflected at least partially toward the mouth  138  of the exhaust duct  112 . Rebounding of such an object, as in prior art devices, and particularly multiple rebounding, of such objects is particularly unlikely. 
     In another embodiment, the transition from the generally round cross-sectional shape of the bottom  122  of the exhaust duct  112  to the generally oval cross-sectional shape of the mouth  138  is accomplished while maintaining equal cross-sectional area in planes perpendicular to a curve running through the center of the exhaust duct  112 . As will be apparent to those skilled in the art, maintaining such a uniform cross-sectional area reduces velocity changes in the airstream which may also contribute to turbulence and noise. 
     In another embodiment, the cross-sectional shapes of the lower portion  122  and mouth  138  of the exhaust duct may have the same shape. For example, both could be round or oval. In such case, the interior of the exhaust duct  112  should still be configured such that the interior walls are smoothly contoured to avoid generation of turbulence. 
     The dirty air exhaust duct  112  and associated components  156 ,  170 ,  172  of the present embodiment may be made of a thermoplastic or thermosetting material or other suitable material by one or more known processes such as injection molding, casting, machining and the like, but preferably is made by injection molding of a thermoplastic material. Even more preferably, the material should be of sufficient rigidity and strength to permit the exhaust duct  112  to function as a component of the elongated handle  103  of the vacuum cleaner  110 . 
     The exhaust duct  112  may be formed in two halves, as illustrated in FIG. 4, and these halves may be joined by any of a variety of known methods, such as the use of vibratory welding, thermal bonding, or solvent or adhesive bonding. 
     The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part with prior art methods to create additional embodiments within the scope and teachings of the invention. 
     Thus, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. The teachings provided herein of the invention can be applied to other structures. In general, in the following claims, the terms used should not be construed to limit the invention to the specific embodiments disclosed in the specification. Accordingly, the invention is not limited by the foregoing disclosure, but instead its scope is to be determined by the following claims.