Abstract:
A pool cleaner, including a valve chamber ( 4 ) having an inlet and two outlet orifices and a valve ( 7 ) within the valve chamber. The valve continuously oscillates between first and second positions due to water flow through the chamber from the inlet to the outlet orifices. A bias means ( 8 ), in the form of resilient projections on the valve ( 17 ), the valve being offset in the chamber or a stiff projection from the valve ( 13 ) contacting the wall of the valve chamber. The bias means applies an eccentric influence on the valve such that the operator does not need to initiate oscillation of the valve.

Description:
[0001]    The invention relates to automatic pool cleaners of the type described by Australian Patents 490972 and 505209, both of which are included herein by reference. In particular, the invention relates to arrangements and methods of operation, which may be implemented so as to reduce the size of an automatic pool cleaner without detrimentally affecting functionality.  
           [0002]    Pool cleaners of the type described above substantially comprise a seal arrangement, sealing a pool surface to a suction zone in fluid communication with a valve chamber. Exiting from said valve chamber are two parallel tubes/passages meeting at a flow attenuation element, which is then connected to a flexible hose. Within said valve chamber there exists a flap valve oscillating between the outlet to each of the tubes. As water flows into the valve chamber, water is drawn up one tube/passage, the mass flow of said water drawing the flap valve over the exit closing off the first tube and creating a water hammer impulse due to the rapid closure. Water is then diverted to the second tube/passage, again drawing the flap valve towards the exit leading to the second tube/passage and, consequently, closing the second tube and diverting water to the first. Therefore, the flap valve oscillates from the first tube/passage to the second tube/passage creating a series of water hammer impulses, which drive the pool cleaner across the pool floor and walls.  
           [0003]    In order to create the desired oscillation frequency and momentum driving the pool cleaner, it has been found that a certain length of tube is desirable. However, for certain applications, and for general economic reasons, it is sometimes desirable to have a pool cleaner with tubes significantly shorter. Because of the complexity of the system, a shortening of the tubes or reduction in internal diameter (ID) does not necessarily equate to an equivalent reduction in size of other components nor the efficiency or effectiveness of the pool cleaner operation due to, inter alia, the reduced mass flow of water oscillating in each tube.  
           [0004]    One problem associated with the use of shorter machines or smaller ID tubes is that of initiating oscillation of the flap valve. It has been found that with a shorter machine instead of the total flow diverting from one tube to the next, the flow is evenly divided between the two tubes/passages. Consequently, the valve fails to start or merely fibrillates in a central position and not thus reaching the extreme positions required to set the pool cleaner in motion. It has been found that the flap valve will oscillate as desired but that operator intervention is required in order to initiate the action.  
           [0005]    It is therefore an object of the invention to automatically initiate the flap valve oscillation on activation of the pool cleaner without an operator having to manually commence the action.  
           [0006]    Therefore, in one aspect of the invention, there is provided a pool cleaner, including a valve chamber having an inlet and two outlet orifices, a valve within the valve chamber adapted to continuously oscillate between a first and a second position due to a water flow through the chamber from the inlet to the outlet orifices and a biassing means adapted to apply an eccentric influence on the valve wherein at initiation of the water flow the biassed means influences the valve towards the first position so as to commence the oscillation.  
           [0007]    An equal division of water flow between the two tubes results in a balance of forces which maintains the flap valve in a central position where it remains stationary or fibrillates.  
           [0008]    The eccentric influence of the present invention provides for a means to turn the symmetrical system into an asymmetrical system by the inclusion of the biassed means. As the water flow enters the valve chamber, the valve will be biassed to one side or the other and thus creates an asymmetrical system initiating the oscillatory action. In any event, the flap must be held away from an extreme position which may close either of the tube/passage apertures.  
           [0009]    Initiation is therefore defined as the commencement of the desired full stroke movement of the flap valve leading to a continuous oscillation. It follows that a differential flow between the tubes will provide an out-of-balance force to the flap valve favouring the tube having the greatest flow. Thus, by applying an imbalance of forces to the valve, the valve will be biassed to one side until it closes off the tube having the least initial flow and permitting a greater flow through the second tube. As a consequence, the valve will be biassed towards the second tube and so the oscillatory action commences.  
           [0010]    Preferably, the biassed means may be an elastic resilient member holding the valve in place and thus its stiffness constant is sufficient to hold the valve whilst not in use but following the commencement of the water flow is insignificant compared to the forces applied to the valve through the change in water flow between the tubes. More preferably, the elastic resilient member may be a rubber member contacting a selected point of the flap valve.  
           [0011]    More preferably, the elastic resilient member may have its primary line of force parallel to the plane transcribed by the movement of the flap valve. Thus, as the resilient member has a contact or connection to the valve chamber aperture wall and the flap valve itself, the connection to the flap valve may be at a central point on an extreme fibre of the valve which traces the peripheral edge of the oscillatory path. In so doing, the resilient member may remain co-linear and resist the forces applied to the flap valve in a purely axial manner. Alternatively, the elastic resilient member may have a line of force substantially orthogonal to the plane transcribed by the oscillatory action.  
           [0012]    Preferably, the biassed means includes a hole or a void in the body of the flap valve placed away from a symmetrical axis of the flap valve. By placing a void offset from a symmetrical axis of the valve, the self weight of the flap valve may act as the biassed means with the void Inclusion providing the eccentric influence. It follows that the larger the void, the greater the out-of-balance forces will be.  
           [0013]    Preferably, the biassed means may be an element located within the flap valve and having a density greater than that of the parent material of the flap valve, said element being located offset from a centre line of the flap valve. In this embodiment, a weighted element may be placed to one side and thus the eccentric influence provided by the weight will be sufficient to provide the imbalance of forces so as to initiate the oscillatory action or reduce the frequency of oscillation.  
           [0014]    Preferably, the biassed means will be at least one relatively stiff member projecting from an internal wall of the valve chamber and in abutting contact with the valve such that the rigidity of the member may be sufficient to hold the flap valve away from an equidistant position between the first and second positions but said stiffness of the elastic member may be insufficient to overcome the forces involved with the oscillatory action and associated mass flow of water.  
           [0015]    The projecting member may be integrally attached to the flap valve. In this case, the projecting member has an integral connection with the flap valve and, thus, on each oscillation the flap valve flexes the projecting member and imparting a flexural and tensile force to said member. Alternatively, the biassed means may include a relatively stiff but elastic projecting member and a corresponding recess in the flap valve such that the member fits within the recess providing an interference for the flap valve to move in an oscillatory motion, said projecting member being of insufficient stiffness to overcome the forces involved with the oscillatory motion of the flap valve.  
           [0016]    Alternatively, the projecting member may be integral with the flap valve and adapted to contact the internal walls of the valve chamber. In this embodiment, the projecting member may be a relatively stiff projection that serves as a stop when contacting the walls of the valve chamber. Alternatively, the projecting member may be elastically resilient so that prior to initiation the flap valve is held in a desired position and following initiation the stiffness of the resilient projecting members is insubstantial compared to the forces during the oscillatory action.  
           [0017]    Preferably, the valve may further include a projection adapted to engage the chamber wall wherein oscillation of the valve occurs through pivoting about said projection. In conventional automatic pool cleaners of this variety, the valve is free to move within the chamber with the chamber shaped so as to guide the valve through a path promoting oscillation. In some circumstances, it may be beneficial for the valve to be connected to the valve chamber using a projection that acts as a pivot. This has a number of advantages including the control of the oscillation frequency and control of the oscillation path.  
           [0018]    More preferably, the pivot projection may be dimensioned or placed so as to impart an eccentric influence upon the valve and so form part of the biassing means. In one preferred embodiment, the projection may be offset from a centre line of the valve. Alternatively, the projection may be non co-linear with a centre line of the valve and the axis of the projection to be skewed to said centre line. In both cases, as water flow commences, there will be an eccentric influence on the motion of the valve, said motion being under the control of the pivoting projection.  
           [0019]    Preferably, the biassed means may be designed so as to control the frequency of the oscillatory action. In all the preceding embodiments of the invention comprising the biassed means, the stiffness of the biassed means has been considered to be insufficient to affect the motion of the flap valve following initiation. If, however, the biassed means can have its stiffness increased, then the higher the stiffness of the biassed means, the lower the frequency of the oscillatory action of flap valve.  
           [0020]    Preferably, the orifice may be located in a demountable orifice plate. For convenient construction of the pool cleaner and to provide access to those elements located within the valve chamber, it may be beneficial to have a portion demountable from the valve chamber. In one embodiment of this convenient demountability of the valve chamber, an orifice plate may provide a convenient means to provide this access, particularly as such a plate may be located on a lower face of the pool cleaner.  
           [0021]    In another aspect of the invention, there is provided a method of initiating the oscillatory motion of a flap valve of an automatic pool cleaner having a first and second tube exiting from a valve chamber, said valve chamber having an inlet orifice and the flap valve adapted to continuously oscillate within the valve chamber between a first and second position due to water flowing through the orifice and the chamber and into the tubes following initiation such that, when in the first position, water entering the inlet orifice is directed into the second tube and, when in the second position, water is directed into the first tube, the steps of the method including biassed the flap valve with a biassed means and drawing the water flow through the orifice and into the valve chamber so that there is a differential flow through the first and second tubes. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0022]    It will be convenient to further described the present invention with respect to the accompanying drawings, which illustrate a possible arrangement of the invention. Other arrangements of the invention are possible and, consequently, the particularity of the accompanying drawings is not to b understood as superseding the generality of the preceding description of the invention.  
         [0023]    [0023]FIG. 1 is an elevation view of the automatic pool cleaner according to the present invention.  
         [0024]    [0024]FIG. 2 is a close-up elevation view of the valve chamber of the automatic pool cleaner of FIG. 1.  
         [0025]    [0025]FIG. 3 is a close-up elevation view of the valve chamber according to a second aspect of the present invention. 
     
    
       [0026]    [0026]FIG. 1 shows an automatic pool cleaner  1  substantially as described in Australian Patent Nos. 490972 and 505209. In particular, the automatic pool cleaner  1  shows parallel tubes  5  and  6  projecting from, and in fluid communication with, a valve chamber  4  in which is located a flap valve  7 . The automatic pool cleaner  1  further includes a sealing arrangement  2  into which is drawn a flow of water, which passes through orifice  3  into the valve chamber  4 . Water is then directed into one of the tubes  5  or  6  as determined by the position of the flap valve  7  at any particular stage. Flap valve  7  is adapted to move within the valve chamber  4  in a single degree of freedom as shown in FIG. 2.  
         [0027]    As shown in the close-up view of the valve chamber  4  in FIG. 2, the flap valve  7  pivots about point  7   a  in an arcuate fashion  9  such that at its extreme points of travel, the flap valve  7  will close off either of the apertures  5   a  or- 6   a . As the water flow  12  travels up tube  5 , the mass flow of water will tend to deflect the flap valve  7  towards aperture  6   a  until it is eventually blocked. This will then direct a greater water flow through aperture  5   a  and into tube  5  and, consequently, draw the flap valve back towards the aperture  5   a  until it is closed off. The motion of the flap valve  7  continues in the oscillatory manner  9  whilst water is drawn up through the automatic pool cleaner  1 .  
         [0028]    The automatic pool cleaner  1  of FIG. 1 being of conventional size and orientation has tubes  5  and  6  of standard length each having the capacity of holding a substantial volume of water. The mass flow of the water in each of these tubes represents a significant force and so on commencement of the operation of the automatic pool cleaner  1 , the flap valve initiates movement immediately. However, because certain applications require a considerably smaller machine and, therefore, tubes/passages  5  and  6  being considerably shorter or of smaller ID, the mass flow of water through said tubes  5  and  6  will be less and so the applied forces to the flap valve  7  may not initiate the oscillatory action  9  without the intervention of an operator.  
         [0029]    The present invention provides means to initiate the oscillatory action  9  by ensuring a differential force is applied to the flap valve  7 . In the preferred embodiment shown in FIG. 2, the means to provide the imbalance of forces is provided through an elastic resilient member  8  connecting the walls of the valve chamber  4  to an extreme point  7   b  of the flap valve  7 . The resilient member  8 , prior to operation of the automatic pool cleaner  1 , positions the flap valve  7  such that its centre line  11  is offset from the centre line of the valve chamber  10  and, thus, creating an asymmetrical system. As problems with initiation of the oscillatory action  9  involve the water flow  12  being equally divided between tubes  5  and  6  and, thus, holding the flap valve  7  in a central position  10 , the preferred embodiment of FIG. 2 solves this problem of symmetrical forces being in balance by creating an offset effect and, thus, permitting a greater flow  12  into tube  5 . Thus, the imbalance of forces applied to the flap valve  7  will naturally deflect the flap valve  7  towards aperture  6   a  and, thus, initiating the oscillatory action  9 .  
         [0030]    Importantly, the elastic resilient member  8  must have a stiffness constant such that, prior to initiation, the flap valve  7  is held in the desired location but following initiation has insufficient stiffness to hinder the oscillatory action  9 .  
         [0031]    [0031]FIG. 3 shows a second aspect of the present invention applied to an alternate constructional arrangement. In this arrangement, the flap valve  7  has a direct connection to the chamber whereby a projection  13  from the flap valve  7  is in a press fit engagement with a portion  14  of the chamber. Whilst in motion  9 , the flap valve  7  oscillates in a pivotal manner about the connection between the projection  13  and the engagement portion  14 . This constructional arrangement is advantageous in providing a further means of biassing the flap valve. In this embodiment, the placement of the projection  13  is such that the axis  16  of the projection  13  is not co-linear with the centre line  11  of the flap valve  7 . The misalignment of the axis  16  and centre line  11  represents a lack of symmetry about the centre line  11  and consequently the movement of the flap valve  7  will be influenced in a direction opposed from the offset represented by the axis  16  and centre line  11 .  
         [0032]    In another preferred embodiment, the flap valve  7  may further include flexural springs  17 , being portions projecting away from the flap valve  7 , which are arranged such that when a leading portion  18  contacts a wall of the chamber  19 , spring energy is developed within the projections  17  biassing the valve  7  in the opposite direction. Where the projections  17  are identical and placed symmetrically about the centre line  11 , said projections will act together in oscillating the valve. When said projections  17  are used with an offset projection  13  about which the valve  7  pivots, the asymmetric alignment of the pivoting motion is such that the projections  17  will not act in an identical manner and will therefore assist in the influencing of the valve  7  and form part of the biassing means.  
         [0033]    Various embodiments of the present invention are herein described with further possible variance described without reference to drawings. It will be appreciated by the person skilled in the art that any of the preferred arrangements of the biassing means and, in fact, various combinations may be incorporated so as to fall within the scope of the present invention. Further, other embodiments may be apparent to the person skilled in the art so as to achieve the result of the present invention and would fall within the scope of the invention as described.