Abstract:
The invention relates to a swimming pool cleaner which is intermittently-turned from its path of travel along an underwater surface. A pair of side wheels ( 3 ) connected to be driven by a turbine ( 8 ) to move the cleaner in a direction of travel. A cam ( 12 ) is provided inwardly of and adjacent to each of the wheels. The cams are rotatably mounted on the wheel axles ( 5 ). Each cam intermittently extends a gripping formation ( 13 ) beyond the operatively supporting surface of the wheel. The cams and gripping formations are arranged so that, when they engage the pool surface, they impart movement to the cleaner which is in the opposite direction to the direction of travel. The cams are preferably arcuate, with at least one radial gripping formation. The rotation of the cams is opposite to that of the wheels and they are driven in a cycle retarded relative to that of the wheels. The gripping formations are removably securable for adjustment on the cams.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to an automatic cleaner for submerged surfaces, particularly in a swimming pool. 
       BACKGROUND TO THE INVENTION 
       [0002]    Automatic swimming pool cleaners of various types are widely known. One group of these has driven wheels, which carry them across submerged surfaces. They may either be suction or pressure operated. 
         [0003]    As with all such automatic cleaners, the ongoing quest is to provide random navigation, without a repeated pattern, and to avoid the cleaner getting trapped against obstacles. 
         [0004]    U.S. Pat. No. 6,782,578 which is limited to a pressure operated pool cleaner suggests at temporarily lifting one wheel or propping one side of the cleaner away from the pool surface to interrupt synchronous rotation of first and second wheels on the pool surface. The suggestion is anticipated by U.S. Pat. No. 5,197,158. The earlier patent discloses a random travel mechanism, located centrally between front and rear wheels and to one side of the cleaner. The mechanism periodically lifts the wheels on that side to cause a skewing of the direction of travel. These teachings with regard to such steering or interrupting mechanisms are respectively insufficient and complicated. From a commercial point of view, it is submitted that there remains room for improvement. 
       OBJECT OF THE INVENTION 
       [0005]    It is an object of the present invention to provide a swimming pool cleaner of the kind referred to which at least partially satisfies the quest. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with this invention there is provided a swimming pool cleaner having a pair of side wheels connected to be driven by a turbine to move the cleaner in a direction of travel along a submerged surface with a cam adjacent at least one of the wheels to intermittently extend a gripping formation beyond the operatively supporting surface of the at least one wheel. 
         [0007]    The invention further provides for the gripping formation to impart movement to the cleaner opposite to the direction of travel. 
         [0008]    Further features of the invention provide for the cam to be rotatably mounted on an axle for the at least one wheel; for the cam to be rotated in the opposite direction to the at least one wheel; for the cam to be arcuate with at least one radial gripping formation on its outer surface; and for the gripping formations to be removably securable to the cam. 
         [0009]    Further features of the invention provide for the cam to be driven in a cycle retarded relative to that of the wheels; for a turbine drive shaft to be connected through gearing to an axle connecting the side wheels, which axle is connected through gearing to a ring gear on the cam; and for a cam to be provided adjacent each of the side wheels. 
         [0010]    Further features of the invention provide for the wheels to be adapted to receive a flotation or ballast body; for the wheels to have tread that securably engages over hub-caps; and for the cleaner to have a second pair of wheels also driven by the turbine. 
         [0011]    Further features of the invention provide for the turbine to be in a housing having an inlet at the underside of the cleaner with a skirt arranged around the inlet to extend downwardly from the underside of the cleaner with at least part of the skirt movably suspended so its free edge is movable inwardly against a resilient bias. 
         [0012]    In accordance with another aspect of this invention there is provided a swimming pool cleaner having a pair of side wheels connected to be driven by a turbine, with a cam adjacent at least one of the wheels to intermittently extend a gripping formation beyond the operatively supporting surface of the at least one wheel and in which the cam is rotatably mounted on an axle for the at least one wheel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]    These and other features of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: 
           [0014]      FIG. 1  shows a plan view of a swimming pool cleaner; 
           [0015]      FIG. 2  shows a part cutaway perspective view of the cleaner; 
           [0016]      FIG. 3  shows a side cross-sectional view; 
           [0017]      FIG. 4  shows a bottom perspective view; 
           [0018]      FIG. 5  shows an exploded view of a wheel for the cleaner; 
           [0019]      FIG. 6  shows a turning cam for a swimming pool cleaner; and 
           [0020]      FIG. 7  shows a bottom perspective view of a cleaner with an alternative skirt arrangement. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    Referring to the drawings, a swimming pool cleaner in accordance with this invention is indicated generally by reference numeral ( 1 ). The cleaner ( 1 ) is shown without any body panels. 
         [0022]    The cleaner ( 1 ) includes a frame ( 2 ), in the form of a pan, which has a pair of side wheels ( 3 ) adjacent its rear end. The rear wheels ( 3 ) have tread ( 4 ) of flexibly resilient material and are fixedly mounted on an axle ( 5 ). The axle ( 5 ) is connected through gears ( 6 ) to the drive shaft ( 7 ) extending from a turbine ( 8 ). The turbine ( 8 ) is mounted in a housing ( 9 ) on the frame ( 2 ). 
         [0023]    Extending upwardly at the top of the housing ( 9 ) is an outlet ( 10 ). The outlet ( 10 ) is connectable to a swimming pool filter pump by a line of flexible hose (not shown) in the usual manner. An opening ( 11 ) in the frame ( 2 ) below the housing ( 9 ) provides an inlet. 
         [0024]    Mounted rotatably about the wheel axle ( 5 ) is a pair of annular cams ( 12 ). Each is adjacent and inwardly of a side wheel ( 3 ). The cams ( 12 ) are of a smaller diameter than the wheels ( 3 ), but carry radial gripping formations ( 13 ) on part of their circumference. These formations ( 13 ) extend beyond the tread ( 4 ) on the wheels ( 3 ). 
         [0025]    Each cam ( 12 ) includes a disc ( 14 ) carrying a ring gear ( 16 ) extending laterally towards the frame ( 2 ). The outer periphery of the gear ( 16 ) is formed as a channel (not shown) which removably receives the gripping formations ( 13 ). The number, size and position of such formations ( 13 ) on the cam ( 12 ) are thus variable. 
         [0026]    A layshaft ( 17 ) supported at the rear end of the frame ( 2 ) extends between the cams ( 12 ) and has sprockets ( 18 ) at its ends which engage the teeth of the gear ( 16 ) to provide rotation of the cams ( 12 ) in the opposite direction to that of the wheels ( 3 ). A further pair of gears ( 19 ) connects the axle ( 5 ) and layshaft ( 17 ) to transmit rotation imparted to the axle ( 5 ) from the turbine ( 8 ). 
         [0027]    The side edges of the frame ( 2 ) are provided with walls ( 20 ) that extend along the length of the frame ( 2 ). A pair of front wheels ( 21 ) is also mounted at the sides of the cleaner ( 1 ). The wheels ( 21 ) have the same tread ( 4 ) and are connected by a front axle ( 22 ). A connecting shaft ( 23 ) extends between the rear axle ( 5 ) and front axle ( 22 ). A pair of cooperating bevel gears ( 24 ) and ( 25 ) respectively at the front and rear ends of the shaft ( 23 ) transmits rotation from the rear ( 5 ) to the front ( 22 ) axle. This arrangement drives the front wheels ( 21 ). The sidewalls ( 20 ) curve upwardly at the front and rear of the frame ( 2 ). The front and rear are shaped so as not to extend beyond the four wheels ( 3 ) and ( 21 ) to any significant degree. 
         [0028]    At the front of the frame ( 2 ) is a bumper ( 26 ). The bumper ( 26 ) is mounted spaced apart forwardly from the cleaner ( 1 ) on a pair of supports ( 27 ). The front edge of the bumper ( 26 ) is curved, from the middle, rearwardly towards the two front wheels ( 21 ). The sidewalls ( 20 ) of the frame ( 2 ) extend downwardly to adjacent the operatively supporting surfaces at the bottom of the four wheels ( 3 ) and ( 21 ). Across the width at the front and rear of the frame ( 2 ) are downwardly extending movable flaps ( 28 ). The sidewalls ( 20 ) and flaps ( 28 ) provide a skirt ( 29 ) around the inlet ( 11 ) at the periphery of the frame ( 2 ). The flaps ( 28 ) are hinged to the frame ( 2 ) at ( 30 ). Extending from the flaps ( 28 ) adjacent the hinges ( 30 ) are levers ( 31 ). The levers ( 31 ) have spaced apart transverse grooves ( 32 ), each of which can removably receive a catch ( 33 ) at the free end of a spring ( 34 ). The other end ( 35 ) of the spring ( 34 ) is anchored to the frame ( 2 ). The tension in the spring ( 34 ) is variable by adjusting the position of the catch ( 33 ) between the grooves ( 32 ). The springs ( 34 ) resiliently bias the lower edges ( 36 ) of the flaps ( 28 ) downwardly. The flaps ( 28 ) adjacent their free, lower edges ( 36 ) are curved inwardly and upwardly. It will thus be understood that part of the skirt ( 29 ) is hingedly suspended so its free edge ( 36 ) is movable inwardly. Furthermore, the parts or flaps ( 28 ) are resiliently biased into their downwardly extending position. 
         [0029]    The wheels ( 3 ) and ( 21 ) are provided with a cavity ( 37 ) to receive an annular body ( 38 ) therein. The body ( 38 ) will either be provided as a float or as ballast, depending on the required tuning of the cleaner ( 1 ). A circlip ( 39 ) engages on the end of the axle ( 5 ;  22 ) to secure the wheels ( 3 ;  21 ) in place. The body ( 38 ) can then be located in the cavity ( 37 ) of the wheel ( 3 ;  21 ) after which a hub-cap ( 40 ) is positioned against the outer edge of the wheel ( 3 ;  21 ). At the outer edge of the tread ( 4 ), an inwardly extending annular lip ( 41 ) is provided. The resiliently flexible lip ( 41 ) is located over the peripheral edge of the hub-cap ( 40 ) to retain it in place over the body ( 38 ). 
         [0030]    In use, the flow of water from the inlet ( 11 ) to the outlet ( 10 ) under action of the pump rotates the turbine ( 8 ) to drive the side wheels ( 3 ) and ( 21 ), which will impart forward motion to the cleaner ( 1 ). The gearing ( 19 ) that drives the cams ( 12 ) is selected so that their cycle of rotation is slower than that of the wheels ( 3 ). The gripping formations ( 13 ) of the reverse rotation cams ( 12 ) intermittently extend beyond the bottom of their respective wheels ( 3 ). The cleaner ( 1 ) advances in a fixed direction along an operating surface until one of the gripping formations ( 13 ) comes into contact with the surface. The wheel ( 3 ) adjacent the cam ( 12 ) is then lifted off the surface. The lifting also inhibits the traction of the front wheel ( 21 ) on the same side of the cleaner ( 1 ). The gripping formation ( 13 ) on the cam ( 12 ) imparts movement to the tilted side of the cleaner ( 1 ) which is opposite to that resulting from the forwardly rotating wheels ( 3 ) and ( 21 ). The cleaner ( 1 ) thus turns under the influence of the cam ( 12 ) and the wheels ( 3 ) and ( 21 ) on the opposite side of the cleaner ( 1 ). With the other wheels ( 3 ) and ( 21 ) in contact with the pool surface, the cleaner ( 1 ) pivots under the resulting turning moment created about the cam ( 12 ). 
         [0031]    The gripping formations ( 13 ) of the two cams ( 12 ) are located at different relative positions so that they will not engage the surface and lift both rear wheels ( 3 ) at the same time. 
         [0032]    When the cleaner ( 1 ) engages an obstacle, the wheels ( 3 ) and ( 21 ) will spin until one of the cams ( 12 ) turns the cleaner ( 1 ) away from the obstruction. The turning is facilitated by the curved bumper ( 26 ), which assists the front end of the cleaner ( 1 ) to disengage the obstacle. 
         [0033]    The skirt ( 29 ) contains a low pressure area below the frame ( 2 ) under the suction of water through the inlet ( 11 ) by the pump. This provides a force on the cleaner ( 1 ) to hold it against submerged surfaces and thus afford traction to the wheels ( 3 ). This also enables the cleaner ( 1 ) to climb vertical walls. The pivotable flaps ( 28 ) of the skirt ( 29 ) serve to prevent the cleaner ( 1 ) from getting stuck by creating a vacuum on, for example, a bump on the floor of a pool. 
         [0034]    Dirt or debris in the immediate vicinity of the cleaner ( 1 ) and specifically within the area under the skirt ( 29 ) is sucked through the inlet ( 11 ), past the turbine ( 8 ) and to the filter pump. 
         [0035]    The gripping formations ( 13 ) on the cams ( 12 ) can be adjusted as required for specific conditions, such as the size of a pool to be cleaned. It will be appreciated that by varying the size, number and position of the gripping formations ( 13 ) so too will the movement pattern of the pool cleaner ( 1 ) be varied. The gearing that drives the wheels ( 3 ;  21 ) and cams ( 12 ) will determine their relative speeds of rotation and this will also affect the pattern of movement. 
         [0036]      FIG. 6  shows a cam ( 12 ) which has three lipped projections ( 42 ). One of these is shown fitted with an engaging formation ( 13 ). The formation ( 13 ), which is made of flexibly resilient material, has a slot (not shown) which provides an interference fit onto the projection ( 42 ). A pair on these cams ( 12 ) will be fitted to a pool cleaner ( 1 ) with the projections offset from each other to avoid simultaneous lifting of the rear wheels ( 3 ). It will be appreciated that the projections ( 42 ) themselves do not extend beyond the tread of the wheels ( 3 ) when the cam ( 12 ) is in place on the cleaner ( 1 ). 
         [0037]    Different arrangements for securing gripping formations to the arcuate cams will be within the design competence of a suitably skilled person. 
         [0038]    The embodiment of the cleaner ( 1 ) shown in  FIG. 7  has an alternative skirt ( 29 ) arrangement around the inlet opening ( 11 ). Front and rear flaps ( 43 ) are made from flexibly resilient elastomeric material. Each flap ( 43 ) has four holes ( 44 ) spaced apart adjacent one edge, opposite to the free edge. These holes ( 44 ) will be pressed onto co-operating enlarged formations (not shown) located on the bottom of the frame ( 2 ). The flaps ( 43 ) are movable within the sidewalls ( 20 ) of the cleaner ( 1 ), under the inherent nature of the material from which they are made. This movement is subject to the configuration of the flaps ( 43 ) with the positioning of ribs ( 45 ) and outer lips ( 46 ) to limit movement in these areas. 
         [0039]    In addition, sidewalls ( 20 ) are recessed between the wheels ( 21 ) and ( 3 ) to receive side flaps ( 47 ). These flaps ( 47 ), which extend laterally between the wheels when in place on the cleaner ( 1 ), are made of the same flexibly resilient material as flaps ( 43 ). Four upward extensions ( 48 ) on each flap ( 47 ) provide an interference fit to corresponding holes (not shown) in the bottom of the frame ( 2 ). The side flaps ( 47 ) assist in maintaining the low pressure area below the frame ( 2 ). The flaps ( 47 ) are cured inwardly at ( 49 ) to allow passage of the formations ( 13 ) on the cams ( 12 ). 
         [0040]    It is common to have the float of a pool cleaner spaced apart from the surface engaging portion thereof. The ballast or weight is normally located close to the surface engaging portion. The combination of a weight and a float are balanced to hold the cleaner in a required orientation when submerged during operation. This often results in a turning moment between these spaced apart components which tends to break contact between the cleaner and the surface being cleaned under certain circumstances. Wheels ( 3 ;  21 ) of the construction shown enable tuning with flotation material or ballast which can be used to mitigate the problem of a turning moment. It will be appreciated that depending on the nature of the body ( 38 ), either a float or a weight can be secured to the frame ( 2 ) of the cleaner ( 1 ). 
         [0041]    The pool cleaner ( 1 ) also has a collapsible wheel assembly, which may include both flexibly resilient wheel components and a flexibly resilient wheel suspension. In the embodiment shown in the drawings, it is the wheel tread ( 4 ) that contributes to the flexibly resilient construction. The arrangement supports the underside of the cleaner ( 1 ) off a surface but gives way under any substantial load when the underside of the frame ( 2 ) provided by the lower edges of the sidewalls ( 20 ) will be pressed against the surface. This protects the components against damage. The cams ( 12 ) will, like the wheels ( 3 ), also add a degree of resilience to the suspension. 
         [0042]    It will be appreciated by suitably skilled persons that a number of variations may be made to the features of the described embodiment without departing from the scope of the invention. 
         [0043]    The cams ( 12 ) need not be annular, and a number of different gear and transmission arrangements for the wheels ( 3 ) and cams ( 12 ) may be used. For example, in a variation of the cam operation, a foot can be driven to extend an inwardly biased engaging formation to engage the operating surface. The formation can extend forwardly from the frame at a suitably inclination to lift an adjacent wheel and to impart the required rearward movement to the frame as it extends. Such an engaging formation could be mounted on an elongate arm which may be curved. As a further alternative, the gripping formation may be provided on an arm having the teeth of a rack along it. The cam will be provided as a co-operating pinion with corresponding teeth on only part of its circumference. The cam will engage the rack only intermittently to extend the engaging formation against an inward bias. 
         [0044]    The cleaner may alternatively be of the pressure operated kind, wherein dirt is entrained and carried into a collection net in known manner.