Abstract:
A baseplate for a robotic self-propelled pool cleaner having one or more inlet openings through which water-borne debris passes prior to filtration is provided with downwardly depending inlet extension members having walls that define an opening corresponding in shape to the baseplate inlet opening and that are mounted in close-fitting relation to extend the water intake opening towards, but without touching, the pool surface to increase the suction force at the surface. The baseplate optionally includes a rotatable wheel mounted in an inboard recess in the baseplate on, or adjacent to the longitudinal centerline of the cleaner to facilitate passage over obstacles that would immobilize the pool cleaner by contact with an inlet extension member.

Description:
FIELD OF INVENTION 
     This invention relates to robotic self-propelled submersible pool and tank cleaners. 
     BACKGROUND OF THE INVENTION 
     Automated or robotic swimming pool cleaners traditionally contact and move about on the pool bottom and wall surfaces being cleaned on four axle-mounted wheels, resilient rollers that are transversely mounted at either end of the unit, or on endless tracks that are powered by a separate drive motor through a gear train to propel the robot over the surfaces of the pool that are to be cleaned. The water pump can drive a water turbine connected via a gear train to the wheels or endless track. Robotic swimming pool cleaners have a pump motor that powers a water pump that draws water through the moving unit and the moving water dislodges and/or “vacuums” debris up into a filter. The water pump can be internal or external to the robotic cleaner. The water exiting the unit having an internal pump in the form of a pressurized stream, or water jet can also be used to move the cleaning apparatus by reactive force. 
     Automated power-driven pool and tank cleaners are provided with pre-programmed solid state control devices to cause random and/or regular patterns of movement of the apparatus. The purpose of the programmed movement is to maximize the probability that the apparatus will cover the entire bottom and, optionally, the side wall surfaces during the cleaning operation in as little time as possible. An efficient cleaning pattern can also be selected based on the shape and size of the pool. 
     Often the bottom of a pool or tank has projections or an uneven surface. These obstacles can stop a robotic cleaner or delay the apparatus with much of the directional cycle spent with the apparatus immobilized or diverted from its intended path by a projecting obstacle or pool surface contour. In either case, this is an undesirable result because it lengthens the cleaning time and wastes externally provided electricity or the power of an on-board battery. Furthermore, the obstacle or contour can change the route of patterned travel of the apparatus, thereby reducing cleaning efficiency. 
     Prior art pool cleaners have addressed the problems of obstacles and extreme surface contours. One prior art method is to reverse and/or change direction of the apparatus when its intended forward movement is prevented. For example, U.S. Pat. No. 6,758,226 to Porat describes an automatic power-driven pool cleaning apparatus in which a motion translation member contacts the surface being cleaned and an associated signal transmitter and a motion sensor is connected to the pool cleaner&#39;s electronic control device. When the cleaner is moving, the motion results in a predetermined signal pattern and when the cleaner stops, the signal pattern is interrupted. After a predetermined period of time, the control device causes the cleaner&#39;s drive means to move the cleaner in a different direction. The obvious drawback is that the regular pattern of travel is changed thereby potentially reducing the efficiency of the cleaning apparatus. 
     Another solution to the problem of obstacles is to raise the baseplate by employing larger diameter wheels or supporting propulsion rollers, or by providing adjustable mounting means so that the user can change the distance between the underside of the baseplate and the pool surface depending upon the specific conditions present in the pool. However, pool cleaners remove dirt and debris from surfaces traversed by applying a suction force proximate to the surface to be cleaned to draw debris that rests on, or that is suspended close to the surface beneath the apparatus through openings in the baseplate and into a filter. The interior edge of the inlet opening is preferably near or on the longitudinal center axis running along the baseplate. Since the suction force diminishes rapidly with an increase in distance between the surface being cleaned and the baseplate inlet openings, merely raising the baseplate is not a practical solution to the problem of obstacles that project from the bottom or sidewall of the pool. 
     It would therefore be desirable to provide a method and apparatus for cleaning the bottom and side walls of pools and tanks that have projecting surface obstacles or extreme contours without stopping or significantly interrupting or altering the cleaning pattern of a self-propelled robotic cleaner. 
     It would also be desirable to provide a means for easily and economically increasing the suction force for existing pool cleaning apparatus in order to provide an improved degree of cleaning for different types of pool surfaces. 
     SUMMARY OF THE INVENTION 
     The above objects and further advantages are achieved by providing one or more inlet extension members that are securely positioned on the exterior surface of the baseplate surrounding each inlet to thereby lower the water intake or suction point of the cleaner. The extension member has walls that define an opening corresponding in shape and size to the baseplate inlet opening and preferably includes projecting mounting members that engage the periphery of the inlet opening to secure the extension member to the baseplate in close-fitting relation so that water will enter the lower open end of the extension member and thereby lower the intake suction point below the baseplate. The downwardly depending walls of the extension member terminate in a rim portion, the rim extending below the baseplate towards, but without touching the pool surface over which the pool cleaner moves during its normal operation. As will be understood by one of ordinary skill in the art, the optimum or maximum depth of the walls is determined by the particular conditions present in the pool or tank in which the cleaner will be operating. As used herein, the term “depth” of the inlet extension member means the vertical distance between the surface of the baseplate and the surface of the rim. 
     In accordance with the invention, interchangeable inlet extension members are positioned on the baseplate to decrease the distance between the inlet opening and the surface of the pool that is being cleaned. Since suction force increases with decreasing distance between the rim of the extension member and the surface being cleaned, inlet extension openings closer to the surface being cleaned increase the efficiency of lifting and moving debris. 
     In one preferred embodiment where the baseplate has at least two inlet openings spaced apart along the central longitudinal axis of the baseplate in the direction of movement and offset on either side of the axis, each of the inlet openings is fitted with an extension member of the same depth. 
     In an especially preferred embodiment, the invention comprises a kit that includes a plurality of extension members of different depths, and in numbers and sizes corresponding to the number of inlet openings in the baseplate of a specific make and model of an existing commercial pool cleaner. For example, in a pool cleaner having a baseplate with two inlet openings, the kit contains two or more pairs of extension members, each pair of different depths and having an opening that is essentially the same as the inlet of the baseplate. 
     In yet another preferred embodiment, a kit consisting of a replacement baseplate and two or more pairs of interchangeable extension members of different depths is provided for use with pre-existing commercial pool cleaners having removable baseplates. The purpose of this baseplate replacement kit is to enable users to obtain the benefits of the extension members on pool cleaners which are constructed in such a manner that the extension members of the invention cannot be retrofitted due to the design of the inlet opening and/or the presence of the movable closures that operate when the movement of water through the inlet opening is started or stopped. 
     Since the user of the pool cleaner will preferably have the option of inserting and removing inlet extension members in order to determine which depth provides the best solution to the pre-existing surface conditions, including the particular type of pool surface, the existence of obstacles and extreme changes in contour, the ability to interchangeably insert and remove the extension members is a significant advantage of the invention. 
     In another embodiment, a baseplate formed by molding a polymeric composition is integrally formed with depending inlet extension members of predetermined depth. Interchangeable baseplates having integrally molded extension members of various depths can be inventoried and made available to purchasers for use with pools having known surface obstructions or conditions. 
     As will also be apparent to one of ordinary skill in the art, the extension members can be sold in kit form for installation using flush mounting means of attachment, including various types of adhesives and mechanical fasteners, e.g., threaded screws. For example, inlet extension members of the same, or approximately the same interior configuration as the inlet opening, can be provided with a mounting tape having release paper that is removed by the user to enable the extension member to be pressed into position around the inlet opening on the external surface of the baseplate. Although this type of mounting tape, when properly selected for the conditions in the pool, can provide a reliable long-term means of attachment, the use of mounting tape also permits the extension member to be removed, e.g., by the insertion of a knife blade or application of a liquid solvent to separate the extension member from its attachment to the baseplate. By using appropriate solvents and/or scraping tools, any remaining adhesive material can be removed from the baseplate and an inlet extension member of the different depth installed. 
     In yet another embodiment, the kit can include a number of inlet extension members corresponding in size and number to the inlets in the baseplate, where each inlet member is formed from a plurality of stackable, snap-fit or otherwise interlocking members that permit the user to vary the depth by changing the number of stackable elements. In a particularly preferred embodiment of this aspect of the invention, the lowermost element is configured to provide a rim surface that will promote laminar flow of the incoming water and minimize turbulence to thereby achieve the optimum efficiency in the flow pattern into the inlet opening. Mounting of the stackable elements can be by use of adhesive means or interlocking brackets that engage the baseplate in accordance with the structures described above for the unitary elements. 
     In yet another embodiment, an extension member is of adjustable depth and constructed of, e.g., close-fitting, interlocking telescoping tubular sections that permit the user to adjust the depth to suit the conditions present in the pool. A wide variety of adjustable constructions are known to those of ordinary skill in the art, as will be their adaptation to the use described above. Set screws and the like can be utilized to maintain one or more telescoping segments in a fixed, but variably adjustable position. 
     As will be understood from the earlier description, extending the suction point below the baseplate can increase the potential for contact with obstacles projecting from the surface being cleaned or engagement with extreme surface contours. In order to obviate this problem, in a further preferred embodiment, the baseplate includes at least one wheel mounted for rotation in a recess positioned adjacent the inlet opening extension member. In an especially preferred embodiment the wheel is displaced inwardly from the lateral edges of the baseplate. 
     In an alternate embodiment, two wheels are mounted for rotation in each recess in the baseplate. 
     In yet another embodiment, the width of the at least one wheel is at least one-quarter of the length of the inlet opening and has the appearance and effect of a roller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in detail below and with reference to the attached drawings in which: 
         FIG. 1  is a bottom perspective view of a baseplate of the prior art in position on a pool cleaner, the later being shown in phantom; 
         FIG. 2  is a view of a baseplate similar to  FIG. 1 , showing inlet extension members of the present invention attached and in position for mounting on the baseplate; 
         FIG. 3  is an enlarged bottom perspective view of a portion of the baseplate of  FIG. 2  showing the installation of the inlet extension member of  FIG. 4 ; 
         FIG. 4  is a side view of one embodiment of an inlet extension member of the invention. 
         FIG. 5  is a side view of another embodiment of an inlet extension member of the present invention; 
         FIG. 6  is an enlarged side view, partially in cross-section, showing a mounting detail of a portion of the inlet extension member of  FIG. 3  taken along line  6 - 6 ; 
         FIG. 7  is a side elevation view of a portion of a pool cleaner immobilized by an inlet extension member contacting an obstacle projecting from the pool surface being cleaned; 
         FIG. 8  is a bottom view of a swimming pool cleaner and baseplate with inlet extension members and wheel recesses of the present invention; 
         FIG. 9  is a view similar to that of  FIG. 7  showing the pool cleaner equipped with the recessed wheels of the present invention rolling over the obstacle; 
         FIG. 10  is a bottom view similar to  FIG. 8  showing another embodiment of the recessed wheels of the invention; and 
         FIG. 11  is a bottom view similar to  FIG. 8  showing yet another embodiment of the recessed wheels of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a representative self-propelled robotic pool cleaner  10  of the prior art has an exterior housing  12 , an internal filter assembly  14 , transverse power driven rollers  16  and a baseplate  20  is schematically depicted. Baseplate  20  is attached to the bottom of the housing  12  and, as illustrated, has two inlet openings  24  that are closed by a pair of biased doors  26  that close when the water flow to the filter is stopped. 
     Referring now to  FIG. 2 , the baseplate  20  has been fitted with an inlet extension member, referred to generally as  30 , that is assembled in a snap-fitting relation; a second inlet extension member is shown in position for attachment to the baseplate. As most clearly shown in  FIGS. 3 ,  4  and  5 , the inlet extension member  30  is formed with a plurality of upwardly projecting members, e.g., clips  36  that are semi-flexible and provided with projecting elements, e.g., ridges  37  that engage the baseplate. 
       FIGS. 4 and 5  are side views of two inlet extension members  32 ,  34  of different depths D 1  and D 2 , respectfully, where “D” generally represents the depth that the inlet extension member  30  extends below the exterior surface of the baseplate  20 . 
     The lesser depth of inlet extension member  34  raises the suction point of the cleaning apparatus closer to the baseplate  20 . The use of an inlet extension member having lesser depth can be beneficial in situations where, for example, obstacles project higher from the surface to be cleaned and would otherwise immobilize or significantly divert the pool cleaner from its intended programmed movement pattern by contacting the rim of the inlet extension member. 
     Referring now to  FIG. 6 , there is shown a cross-sectional view of the inlet extension member  32  viewed along the section line  6 - 6  of  FIG. 3 . The extension member  32  (or  34 ) is removable from the baseplate  20  and includes at least one wall  40  having an outer surface  42  and inner surface  43 , where the outer surface  42  is configured to correspond in size and shape to the baseplate water inlet opening  24  formed through the baseplate  20  of the pool cleaner  10 . The inner surface  43  of the at least one wall  40  defines an extended inlet for drawing the pool water through the baseplate inlet extension member  32 . The at least one wall  40  extends substantially perpendicular from the substantially planar exterior surface  23  of the baseplate  20  towards the distally adjacent pool surface over which the pool cleaner  10  moves during nomial operation and terminates in a rim portion  44 . As shown in  FIGS. 3 and 6 , the rim portion  44  extends radially outwards to define a flange which circumscribes the baseplate water inlet opening  24 . Preferably, the outwardly extending flange of the rim portion is curved from the inner surface  43  or outer surface  42  of the wall  40  towards the planar exterior surface  23  of the baseplate  20 . In  FIG. 5 , the extension member  34  illustratively has a predetermined depth of “D 2 ”, whereas referring to  FIGS. 4 and 6 , the extension member  32  has a depth of “D 1 ”. Installing an extension member having a predetermined depth, e.g., D 1  or D 2 , is based on the surface conditions of the pool and the amount of suction desired, as described below in further detail. The projecting elements  37  (e.g., ridges) engage the interior surface  21  of baseplate  20 . In a preferred embodiment, the projecting member  36  (e.g., clip) is sufficiently flexible to permit its disengagement and removal. 
     As shown in the illustration of  FIG. 7 , the lower rim surface of inlet extension member  30  can project sufficiently below baseplate  20  that it comes into frictional contact with obstacles projecting above the surface  202  of the pool that is being cleaned. As shown, a water inlet cover  200  projects above pool surface  202  and the pool cleaner  10  is immobilized as a result of one or both of rollers  16  making insufficient frictional contact to maintain the movement of the unit. 
     In order to remedy this problem where the pool cleaner is used in pools having obstacles projecting from the surface being cleaned, the baseplate is provided with one or more recesses for receiving axle-mounted wheels. Referring now to  FIG. 8 , recesses  70  are positioned adjacent the inlet extension members  30  and a wheel  80  mounted on an axle  81  is secured for rotation in each recess. 
     As best shown in  FIG. 9 , the wheels  80  project at least to the depth of the extension member  30 , and preferably slightly deeper below the baseplate. This enables the pool cleaner  10  to ride up and over the projecting obstacle  200 , thereby avoiding the immobilization and/or the diversion of the unit from its programmed cleaning pattern. 
     The axle-mounted wheels are preferably removably mounted in the recess  70 . This can be accomplished by various mechanical fastening techniques that will be apparent to one of ordinary skill in the art, including molding channels in the baseplate that communicate with the recess and into which one or both of the opposing ends of the axle can be inserted in a releasable snap-fit relation; or by a mechanical fastener, e.g., a screw and optionally a bracket that retains the free end of the axle in position. This arrangement allows the user to determine whether a wheel is necessary and, if so, the option of selecting a wheel, or set of wheels, of a diameter that is appropriate for the height of projecting obstacles present in the pool. In this manner, the user can customize the pool cleaner based upon the conditions present in the pool. 
     In a particularly preferred embodiment, the recesses  70  are large enough to accommodate wheels of various diameters and the wheels are either sold to the user as a kit or by a supplier who maintains an inventory from which the user can select the appropriate sized wheels and accompanying inlet extension members  30 . 
     As shown in the embodiment of  FIG. 8 , wheels  80  can be on opposite sides of the longitudinal centerline of the pool cleaner. These offset wheels permit the pool cleaner to ride over obstacles and prevent the apparatus from being immobilized on a pool drain cover or other protrusions from a surface over which the apparatus is traveling. 
     Again, with reference to  FIG. 9 , the wheels  80  roll over the projecting surface obstacle, e.g., pool drain cover  200  by preventing the inlet extension member  30  from contacting the obstacle. Referring to  FIG. 9 , it will also be understood that the wheels  80  can extend the same distance or less than the distance from the baseplate  20  as rollers  16 , or other drive means that support the pool cleaner for movement. 
       FIG. 10  illustrates an alternate embodiment of the invention shown in  FIG. 8 , where a set of two wheels  82  are positioned in each of two sets of separate wheel recesses  70  positioned on opposite sides of the baseplate center line and adjacent the respective inlet extension members  30 . 
     As shown in  FIG. 11 , the baseplate can also be configured so that a large recess  72  replaces each of the pair of recesses  70  shown in  FIG. 10  so that a single roller  84 , or two or more wheels (not shown) are mounted for rotation in each of the large recesses. 
     As also shown in phantom in  FIG. 11 , a single large recess  74  is centrally positioned between the two inlet extension members  30  to accommodate a single larger roller  86 , or a plurality of wheels (not shown) mounted on a single releasable axle. 
     As previously explained, in order to optimize the position of the inlet opening and to maximize the amount of suction force to remove debris from the surface being cleaned, the present invention provides interchangeable inlet extension members which can be used to lower the suction point relative to the surface being cleaned. The interchangeable extension members can also be used to decrease the effective area of the suction openings to thereby increase the velocity of the water drawn into the inlet opening. When used in combination with the recessed wheels, the inlet extension members provide improved cleaning efficiency, even in pools having surface obstacles that could otherwise interfere with the patterned movement of the cleaner. 
     While the foregoing is directed to various embodiments of the present invention, additional embodiments will be apparent to those of ordinary skill in the art without departing from the basic principles and the scope of the invention is to be determined by the claims that follow.