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FIELD OF THE INVENTION 
     This invention relates to (automatic) swimming pool cleaners and in particular to bumpers for and other components of such cleaners. 
     BACKGROUND OF THE INVENTION 
     A variety of devices exist that move automatically over surfaces of swimming pools to be cleaned. One such pool cleaner operates in cooperation with the reduced pressure caused by a pump to induce debris-laden fluid within a pool to flow through the cleaner (and other filtration equipment if desired). The cleaner functions by causing a valve, or diaphragm, to oscillate, periodically interrupting the fluid flow through the cleaner. This periodic interruption in turn causes movement of the device over the surface to be cleaned. Exemplary cleaners of this type are disclosed in U.S. Pat. Nos. 4,642,833 and 4,742,593, which patents are incorporated herein in their entireties by this reference. 
     U.S. Pat. No. 5,014,382 (“the Kallenbach patent”), also incorporated herein in its entirety by reference, discloses another fluid-interruption version of an automatic swimming pool cleaner. Illustrated in the Kallenbach patent as being attached to the cleaner are a bumper and a retainer that includes a weight. The retainer, which is integrally formed with a portion of the body of the cleaner, thereby fixes the position of the weight relative to the body. Moreover, rigid plastic is used to form the bumpers of commercially-available cleaners made according to the Kallenbach patent. As noted in the Kallenbach patent (col. 3, line 65 through col. 4, line 3), the bumper, when it contacts an obstruction, assists in lifting the flexible disc of a cleaner 
      from the surface and thus breaking the pressure holding the disc . . . to the surface being traversed. This allows the cleaner . . . to move freely until it disengages from the obstruction. 
     SUMMARY OF THE INVENTION 
     The present invention, by contrast, provides alternative bumper assemblies for swimming pool cleaners. Unlike the bumper of the Kallenbach patent, for example, that of the present invention may include a flexible edge, or fin, attached to the main frame of the bumper. The fin and contour of the main frame facilitate deflection of the associated cleaner when obstacles are encountered. They also aid in the cleaner transitioning from traversing the bottom of the pool to cleaning its sides. The ability of the cleaner to climb steps sometimes found in pools additionally is enhanced by the shape of the frame. 
     Further features of the present invention include side wings connecting the frame to the body of the cleaner. These wings too may have flexible leading edges to promote deflection of the cleaner when obstacles (particularly steps and ladders) are encountered. The side wings, as well as the frame, also reduce cleaner body wear that otherwise would occur from frictional contact with the walls of and obstacles placed within swimming pools. 
     Unlike the cleaners of the Kallenbach patent, moreover; those of the present invention include a mobile—rather than stationary—weight. The weight, in some embodiments positioned about a tapered section of the main frame of the bumper assembly, is adapted to slide, or move, in two axes: longitudinally along the length of the section and laterally across its (tapered) width. Such movement occurs automatically as the cleaner operates, effectively continuously rebalancing it depending on its location and orientation within the pool. The action of the weight can also result in increased pool coverage per unit time by the cleaner. 
     Additionally optionally included in cleaners of the present invention is another, “belly” weight as well as a lower bumper assembly. Positioned above and adjacent the flexible disc, the lower bumper facilitates operation of a cleaner by reducing the likelihood of the cleaner becoming trapped against an object such as a step located within a swimming pool. More or less horizontal when the cleaner is upright and generally parallel to the disc, the lower bumper forms the leading edge of the bottom of the cleaner body when the cleaner approaches an object other than perpendicularly. It thus is able to function as a sacrificial member, itself wearing by contact with objects rather than permitting the cleaner body to do so. 
     In some embodiments of the invention, the lower bumper may be comprised of two sections, the sections being integrally or otherwise connected at one, “first” end and connectable at the other, “second” end of each. The first end may effectively function as a hinge, permitting expansion of the interior of the bumper to allow it to be placed about the exterior of a cleaner body. Once so placed, the second ends of the sections may be brought into contact and latched, or connected, in position. The lower bumper additionally may attach to the main frame of the finned bumper at one or more locations, utilizing protrusions fitted into (and, if desired, interlocking with) corresponding bosses or collars included as part of the main frame. 
     It is therefore an object of the present invention to provide bumpers or bumper assemblies for an automatic swimming pool cleaner. 
     It is also an object of the present invention to provide bumper assemblies adapted to facilitate deflection of the cleaner when obstacles are encountered in use. 
     It is another object of the present invention to provide bumper assemblies in which such deflection is facilitated by a flexible fin, which in at least some embodiments is attached to a rigid, contoured frame. 
     It is a further object of the present invention to provide side wings, or similar wear-preventing structures, connecting the frame to the body of the cleaner. 
     It is yet another object of the present invention to provide a system, repositionable in use, for balancing the cleaner with which it is associated. 
     It is also an object of the present invention to provide such a system that includes a weight adapted to move along two axes. 
     It is an additional object of the present invention to provide such a system in which the action of the weight can result in increased pool coverage per unit time by the cleaner. 
     It is, moreover, an object of the present invention to provide bumpers positioned more or less parallel to flexible discs of cleaners and adjacent such discs. 
     It is furthermore an object of the present invention to provide a bumper comprised of two sections, the sections being effectively hinged at one end and connectable at the other. 
    
    
     Other objects, features, and advantages of the present invention will become apparent with reference to the remainder of the text and the drawings of this application. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of portions of a swimming pool cleaner containing a bumper assembly of the present invention. 
     FIG. 2 is a side elevational view of the swimming pool cleaner of FIG.  1 . 
     FIG. 3 is a partially-exploded side elevational view illustrating the main frame and fin of the bumper assembly of FIG.  1 . 
     FIGS. 4A and 4B are diagrammatic views illustrating various positionings of a weight assembly useable as part of the bumper assembly of FIG.  1 . 
     FIG. 5 is an exploded perspective view of the weight assembly of FIG.  4 . 
     FIG. 6 is a top view of a lower bumper useful as part of the present invention. 
     FIG. 7 is a perspective view of the lower bumper of FIG.  6 . 
     FIG. 8 is a perspective view of a swimming pool cleaner showing exemplary relative locations of the bumper, side wings, and lower bumper of FIGS.  1  and  6 . 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1-2 show an exemplary automatic swimming pool cleaner S to which bumper assembly  10  of the present invention is connected. As with many commercially-available pool cleaners, cleaner S includes a body  14  to which an extension pipe  18  is attached or formed. Also used as part of cleaner S are a footpad  22 , shown in FIGS. 1-2, and a flexible disc  26 . Cleaner S typically moves generally in the direction of arrow A when upright, thus often making bumper assembly  10  the leading edge of the cleaning device. 
     Included in embodiments of assembly  10  are bumper  30 , weight assembly  34 , and side wings  38 . FIG. 3 illustrates bumper  30 , which in the illustrated embodiment is oriented approximately forty-five degrees from the horizontal plane when body  14  is upright and comprises main frame  42  and fin  46 . Frame  42  may be formed of plastic or other material that is substantially rigid, while fin  46  is normally composed of flexible material such as polyurethane (or any appropriate thermoplastic elastomer or rubber or other flexible material). Fin  46  is designed to attach to frame  42  in any suitable manner, including (although not exclusively) through use of a water-insoluble adhesive. 
     The flexibility and curvature of fin  46  facilitate deflection of cleaner S should it encounter certain obstacles in a pool. These characteristics of fin  46  additionally enhance the ability of cleaner S to climb any underground stairs in the pool, promoting cleaning of their otherwise relatively hard-to-access perpendicular surfaces. The contour of fin  46  further assists cleaner S in the transition from cleaning the bottom of a pool to cleaning one of its sides. 
     Frame  42  may include opening  50 , in which collar  54  may be incorporated. Although not readily visible in FIG. 3, collar  54 , when present, may protrude from both surface  58  of frame  42  and from its opposite (reverse) surface  60 . Collar  54  is adapted to receive side wings  38 , as described hereafter in greater detail; in its absence, such wings  38  may in some cases simply be received by opening  50 . 
     Additionally contained as part of frame  42  are split collars  62 A and  62 B. Each semi-cylindrically shaped, split collars  62 A and  62 B connect frame  42  to (cylindrical) extension pipe  18  of cleaner S. The mechanical fit provided by split collars  62 A and  62 B retains them in place, thus fixing the position of frame  42  relative to extension pipe  18 . In some embodiments of bumper assembly  10 , split collars  62 A and  62 B are integrally formed with frame  42 . This is not necessary, however, as water-insoluble adhesives or other connection media alternatively may be employed. Those skilled in the art will also recognize that other mechanisms for connecting the frame  42  to cleaner S may be used instead of split collars  62 A and  62 B and that neither collars  62 A and  62 B nor pipe  18  need necessarily be cylindrically shaped. 
     To brace the connection with cleaner S, frame  42  further may contain a recess or slot  66  into which a corresponding protrusion  68  extending from body  14  is fitted. If necessary or desired, a clip  70  may also be included as part of frame  42  for connection to body  14 . Neither slot  66  nor clip  70  is required for satisfactory operation of bumper assembly  14 , although having either or both may improve the deflection response of bumper  30  when it contacts an obstacle within a pool. 
     Additionally included as part of frame  42  is tapered section  74 . Preferably (although not necessarily) integrally formed as part of frame  42 , tapered section  74  provides surfaces  78  and  82  along which weight assembly  34  slides. Surfaces  78  and  82  are, in embodiments of the invention consistent with FIG. 3, perpendicular to surfaces  58  and  60  of frame  42 . They need not be ninety degrees removed, however, nor must they be flat as illustrated in the figure. 
     FIGS. 4A and 4B show the contour of an exemplary section  74 . In particular, section  74  has minimum width W min  at or near its top  86 . By contrast, maximum width W max  exists for section  74  at or near its bottom  90 . Section  74  further includes stop  94 , which protrudes from and typically is integrally formed with surface  78 . A second stop may be formed with surface  82  if appropriate or desired. 
     FIGS. 4A and 4B, as well as FIG. 5, detail weight assembly  34  of the present invention. In preferred embodiments of the invention, weight assembly  34  comprises both a weight  96  and a housing  98  (which may comprise at least connectable components  98 A and  98 B) in which weight  96  is placed. In these embodiments, housing  98  is designed so as not to permit weight  96  to move therein but rather to secure it in place. 
     During manufacture of bumper assembly  10 , housing  98  of these embodiments may be fitted about section  74 . If necessary for replacement or repair, housing  98  may be made to be removable from section  74 . Otherwise, housing  98  is intended to remain surrounding section  74  throughout operation of pool cleaner S. 
     As shown in FIG. 4B, the internal width of housing  98  is approximately equal to W max . As a consequence, when housing  98  approaches bottom  90  of section  74 , it cannot move significantly laterally across the section  74 . By contrast, the internal width of housing  98  is substantially larger than W min . Accordingly, as housing  98  approaches top  86  of section  74 , its lateral movement is relatively uncircumscribed (as shown in FIG.  4 A). To prevent housing  98  from lodging (jamming) near bottom  90  of section  74 , stop  94  may be employed. 
     When cleaner S traverses the bottom of a pool with body  14  upright, weight assembly  34  is typically stationary, positioned near bottom  90  abutting stop  94 . As cleaner S successfully climbs to the top of the side wall of a pool, its natural tendency is to turn and move horizontally along the side wall rather than return to the pool floor. However, as cleaner S begins to become oriented horizontally, weight assembly  34  commences movement (sliding) along section  74  from bottom  90  toward top  86 . Movement of weight assembly  34  changes the balance of cleaner S by increasing the moment around an axis perpendicular to the side wall of the pool, causing cleaner S to dive back down to the bottom of the pool. When cleaner S reaches the pool bottom and body  14  is again upright, weight assembly  34  returns to its nominal resting position abutting stop  94 , and cleaner S continues traversing the bottom of the pool. In many cases, the action of weight assembly  34  enhances the rate of pool coverage cleaner S can provide. 
     Side wings  38 , when present, help reduce wear of body  14  occurring because of frictional contact of the body  14  with walls of and obstacles within a swimming pool. FIG. 1 illustrates two such wings  38  oriented substantially horizontally (in contrast to bumper  30 ), each having an end  102  received by collar  54 . Ends  102  are fitted or otherwise adapted so as to be retained within collar  54  as cleaner S operates, with wings  38  thereby shielding body  14  from certain contacts. Opposite ends  106  of wings  38  are typically connected to body  14  in any suitable manner. Like bumper  30 , wings  38  may have flexible leading edges  110  to promote deflection of cleaner S when obstacles—particularly steps and ladders—are encountered. Any cleaner S with which the present invention is utilized is thus capable not only of enhanced performance in diving to the bottom of a pool, but also of having increased useful life because of decreased wear. 
     FIGS. 6 and 7 illustrate lower bumper  120  of the present invention. Bumper  120  may include frames or sections  124  and  128 , each having a first end  132 A and  132 B, respectively, and a second end  136 A and  136 B. In the bumper  120  of FIGS. 6 and 7, first ends  132 A and  132 B are shown as being integrally forted, with an area  140  of reduced width between them. Those skilled in the art will recognize that first ends  132 A and  132 B need not be integral, but instead may be connected in any appropriate manner. If present, area  140  of reduced width may function as a hinge, permitting second ends  136 A and  136 B to open to facilitate attaching bumper  120  to a swimming pool cleaner S (as in FIG.  8 ). 
     As with bumper  30  and wings  38 , sections  124  and  128  of bumper  120  may have flexible leading edges  144 A and  144 B. Leading edges  144 A and  144 B preferably are made of polyurethane, although any suitable thermoplastic elastomer or rubber (or other flexible material) may be used instead. They too promote deflection of cleaner S when they contact objects, such as steps, within a pool. 
     Detailed in FIGS. 6 and 7 are connector sets  148 ,  150 , and  151 . Set  148  comprises protrusions  148 A and  148 B and complementary recesses  152 B and  152 A. Closing second ends  136 A and  136 B causes protrusion  148 A and recess  152 B and protrusion  148 B and  152 A to engage, enclosing a rectangular space  156 . In use, bumper  120  is fitted about footpad  22  or a portion of body  14  abutting the footpad  22  or adjacent thereto, with the footpad  22  or body  14  filling part or all of space  156 . Those skilled in the art will understand that space  156  need not necessarily be rectangular, but rather may have any appropriate or suitable shape. Likewise, bumper  120  need not necessarily connect with footpad  22  or body  14 ; instead, it may attach to or be formed as part of other components of cleaner S as desired. Preferably, however, space  156  indeed is rectangular, and connector set  148  latches underneath a flange of body  14  above footpad  22 . 
     Connector sets  150  and  151  are designed to connect bumper  120  to frame  42  of bumper  30 . FIG. 8 illustrates possible positionings of bumper  120 , frame  42 , and side wings  38  relative to each other and body  14  of automatic swimming pool cleaner S. As shown in FIG. 8, bumper  30  may be contoured differently than appears in FIG. 1 in order suitably to receive bumper  120 . 
     Connector set  150  may comprise protrusions  150 A and  150 B, each adapted to be received by and engage a boss such as (or similar to) collar  54 . However, because the mechanism for connecting bumpers  120  and  30  is not critical to the invention, bosses or collars need not necessarily be present (and thus are not shown in FIG.  8 ), and set  150  may be configured other than as protrusions  150 A and  150 B. Connector set  151  likewise comprises protrusions  151 A and  151 B designed to be received by a boss, collar, or opening of some sort. Protrusions  151 A and  151 B may be similar to protrusions  150 A and  150 B, although preferably they have smaller diameter and are oriented ninety degrees from the orientation of protrusions  150 A and  150 B. Again, however, set  151  need not be configured as shown in FIG. 8, and other methods of connecting bumpers  30  and  120 , if such is desired, may be utilized. 
     In use, bumper  120  extends beyond the periphery of disc  26 . In some planes and paths of travel, therefore, second ends  136 A and  136 B or edges  144 A or  144 B of bumper  120  form the leading edge of pool cleaner S. Should a cleaner S approach an underwater object along such a path, bumper  120  will produce the initial contact with the object, deflecting the cleaner S along a new path and thereby reduce the possibility of its becoming stuck against the object. Flexible edges  144 A and  144 B facilitate this deflection, providing sacrificial, high-wearability bearing surfaces with substantial curvature. Alternatively, however, edges  144 A and  144 B may be partially or wholly rigid or be angled or inclined rather than curved. 
     The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention.

Summary:
Bumpers and assemblies for swimming pool cleaners are disclosed. Such assemblies may include contoured frames to which flexible fins are attached to facilitate deflection of cleaners when obstacles are encountered. Side wings connecting the frame to the body of a cleaner may additionally be employed as part of the assemblies, as may a weight moveable about two axes. In use, the side wings both promote cleaner deflection and reduce body wear that otherwise would occur. The non-stationary weight permits continuous rebalancing of the cleaner depending on its location and orientation within a pool. An optional lower bumper facilitates operation of the cleaner by reducing the likelihood of its becoming trapped against objects such as steps located within swimming pools.