EP0835357B1 - Automatic swimming pool cleaning system - Google Patents

Abstract

Automatic swimming pool cleaning method and apparatus for cleaning a water pool (1) contained in an open vessel (2) defined by a containment wall (3) having a bottom (4) and side (5) portions utilizing a unitary structure or body (6) configured for immersion in a pool (1) for selective operation proximate the water surface (7) in a surface cleaning mode or proximate to the interior wall surface portions (8) in a wall surface cleaning mode.

Description

The present invention relates to a method and apparatus suitable for cleaning aswimming pool.

The prior art is replete with different types of automatic swimming pool cleaners.They include water surface cleaning devices which typically float at the watersurface and can be moved across the water surface for cleaning, as by skimming.The prior art also shows pool wall surface cleaning devices which can rest at thepool bottom and can be moved along the wall (which term should be understoodto include bottom and side portions) for wall cleaning, as by vacuuming and/orsweeping. Some prior art assemblies include both water surface cleaning and wallsurface cleaning components tethered together.

Document US-A-4,154,680 discloses an apparatus for underwater cleaning of aswimming pool wall. The device is characterized by a chassis carrying electricmotors. The electric motors drive a traction assembly which propels the chassisalong the wall surface. The electric motor is used to create suction for drawing dirtfrom the wall surface. A controlled diving cell is mounted on the chassis which ispowered by the electric motor to facilitate raising the chassis. The chassis is notbeing operated near the water surface to clean the surface water.

Document US-A-4,994,178 describes a heavier-than-water device intended to bedrawn in submerged condition through the water by a flexible hose. The deviceincludes a wing assembly which orients the open mouth of a collection bag so thatis collets debris from the wall surface. This document does not describe orsuggest any mechanism for lifting the heavier-than-water device to the watersurface for collecting debris at the water surface. Rather, the device is merelytowed so as to enable its bag to collect debris from the wall surface.

Document US-A-4,040,864 shows a self propelled skimmer for removing debrisfrom the water surface of a pool. There is no discussion or suggestion in thatdocument of causing the skimmer device to descend to collect debris from the wallsurface.

Document US-A-4,849,024 describes a swimming pool cleaner which has ahousing to which suction is applied via a flexible hose. The cleaner rests on thefloor of the pool and cleans the surface thereof.

The present invention is directed to a method and apparatus useful for cleaning awater pool contained in an open vessel defined by a wall having bottom and sideportions.

Apparatus in accordance with the invention includes (1) a unitary structure or bodycapable of being immersed in a water pool and (2) a level control subsystem forselectively moving the body to a position either proximate to the surface of thewater pool for water surface cleaning or proximate to the interior surface of thevessel wall for wall surface cleaning.

Embodiments of the invention can use either a heavier-than-water body or alighter-than-water body. When a heavier-than-water body is used, the body in its quiescent or rest state typically sinks to a position proximate to the bottom portion ofthe vessel wall. In an active state, the level control subsystem produces a vertical forcecomponent for lifting the body to proximate to the water surface for operation in a watersurface cleaning mode.

When a lighter-than-water body is used, the body in its quiescent statefloats at a position proximate to the water surface. In an active state, the level controlsubsystem produces a vertical force component for causing the body to descend toproximate the wall bottom portion for operation in a wall surface cleaning mode.

When in the water surface cleaning mode, debris is collected from the watersurface. When in the wall surface cleaning mode, debris is collected from the wallsurface.

Embodiments of the invention preferably also include a propulsionsubsystem for producing a nominally horizontal force component for moving the bodyalong (1) a path adjacent to the water surface when the body is in the water surfacecleaning mode and (2) a path adjacent to the wall surface when the body is in the wallsurface cleaning mode.

Preferred embodiments of the invention are configured to be hydraulicallypowered, either from the pressure or suction side of an external hydraulic pump.Proximal and distal ends of a flexible supply hose are respectively coupled to the pumpand body for producing a water supply flow through the body for powering theaforementioned subsystems. The hose is preferably configured so that it typicallyprimarily lies close to the vessel interior wall surface with the hose distal end beingdragged along by the movement of the body.

More particularly, in the exemplary preferred embodiments, the water supplyflow is directed by one or more control elements (e.g., valve), to directly or indirectly,create water flows for producing the vertical and horizontal force componentsrespectively needed for level control and propulsion. A preferred propulsion subsystemcan define either a normal state in which a force component is produced for moving the body in a forward direction, and a backup state for producing a force component formoving the body in a rearward direction. Water surface and wall surface cleaningtypically occurs during the normal propulsion mode. The backup propulsion state ispreferably initiated to enable the body to free itself from obstructions.

The body preferably carries a water permeable debris container. In thewater surface cleaning mode, a flow of surface water is created through the debriscontainer which removes floating debris from the water surface. In the wall surfacecleaning mode, a water flow from adjacent to the wall surface is created for vacuumingdebris from the wall surface.

The operating modes of the level control subsystem are preferably switchedautomatically in response to the occurrence of an event such as the (1) expiration of atime interval, (2) the cycling of the external pump, or (3) a state change of the propulsionsubsystem. The operating states of the propulsion subsystem are preferably switchedautomatically in response to the occurrence of an event such as the expiration of a timeinterval and/or the interruption of body motion.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A and 1B respectively schematically depict heavier-than-water andlighter-than-water embodiments of the invention shown in water pools contained in openvessels;

Figure 2 is a functional block diagram generally depicting level control andpropulsion control subsystems utilized in preferred embodiments of the invention;

Figures 3-7 illustrate a first structural embodiment of the invention capableof selectively operating in (1) a water surface cleaning mode and (2) a wall cleaningmode;

Figure 8 is a flow diagram describing the operation of the embodiment ofFigures 3-8;

Figures 9-14 illustrate a second structural embodiment of the inventioncapable of selectively operating in (1) a water surface cleaning mode and (2) a wallcleaning mode;

Figure 15 is a flow diagram describing the operation of the embodiment ofFigures 9-14;

Figures 16-19 illustrate a third structural embodiment of the inventioncapable of selectively operating in (1) a water surface cleaning mode and (2) a wallcleaning mode;

Figure 20 is a flow diagram describing the operation of the embodiment ofFigures 16-19;

Figures 21-26 illustrate a fourth structural embodiment of the inventioncapable of selectively operating in (1) a water surface cleaning mode and (2) a wallcleaning mode; and

Figure 27 is a flow diagram describing the operation of the embodiment ofFigures 21-26.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to Figures 1A and 1B, the present invention is directed toa method and apparatus for cleaning awater pool 1 contained in anopen vessel 2defined by acontainment wall 3 havingbottom 4 and side 5 portions. Embodiments ofthe invention utilize a unitary structure or body 6 capable of being immersed in thewaterpool 1, for selective operation proximate to the water surface 7 (water surface cleaningmode) or proximate to the interior wall surface 8 (wall surface cleaning mode).

The unitary body 6 preferably has a hydrodynamically contoured exteriorsurface for efficient travel through the water. Although bodies 6 in accordance with theinvention can be very differently shaped, it is intended that they be relatively compact insize fitting within a 0.6 m (two foot) cube envelope. Figure 1A depicts a heavier-than-water body6 which in its quiescent or rest state typically sinks to a position (shown in solid line)proximate to thebottom portion 4 of thevessel wall 3. In an active state, the body 6 islifted to a position (shown in dash line) proximate to the surface 7 ofwater pool 1.Alternatively, Figure 1B depicts a lighter-than-water body 6 which in its quiescent or reststate rises to proximate to the surface 7 ofwater pool 1. In an active state, the body 6is caused to descend to thebottom 4 portion ofwall 3. The active state in either Figure1A or Figure 1B is typically produced in accordance with preferred embodiments of theinvention by a water fiow throughflexible hose 9 to or fromhydraulic pump 10.

The body 6 is essentially comprised of upper and lower portions, 6U and6L respectively, spaced in a nominally vertical direction, and front and rear portions, 6Fand 6R respectively, spaced in a nominally horizontal direction. A traction means suchas wheels 11 are typically mounted adjacent the bodylower portion 6L for engaging thewall surface 8.

Embodiments of the invention are based, in part, on a recognition of thefollowing considerations:

1. Effective water surface cleaning (skimming) reduces the overall taskof swimming pool cleaning since most debris in the water and on the vessel wall surfacepreviously floated on the water surface.

2. A water cleaner capable of floating or otherwise traveling to the sameplace that the debris floats can capture debris more effectively than a fixed position built-inskimmer.

3. A water surface cleaner can operate by using a weir, a waterentrainment device, or by scooping up debris as it moves across the water surface. Thedebris can be collected in a water permeable container.

4. A single unitary structure or body can be used to selectively operateproximate to the water surface in a water surface cleaning mode and proximate to thewall surface in a wall surface cleaning mode. A common debris collection container canbe used in both modes.

5. The level of the body in the water pool. i.e., proximate to the watersurface or proximate to the wall surface, can be controlled by a level control subsystemcapable of selectively defining either a water surface mode or a wall surface mode. Themode defined by the subsystem can be selected via a user control, e.g., a manual switchor valve, or via an event sensor responsive to an event such as the expiration of a timeinterval.

6. The movement of the body in the water pool can be controlled bya propulsion subsystem, preferably operable to selectively propel the body in either aforward or rearward direction. The direction is preferably selected via an event sensorwhich responds to an event such as the expiration of a time interval or an interruptionof the body's motion.

7. A cleaning subsystem can be operated in either a water surfacecleaning mode (e.g., skimming) or a wall surface cleaning mode (e.g., vacuuming orsweeping).

8. The subsystems can be powered from a common source or fromdifferent sources which can include hydraulic (either positive or negative pressure),pneumatic, and electrical.

Four exemplary embodiments of the invention will be described hereinafter.All of these embodiments will be assumed to utilize a heavier-than-water body which ina quiescent state rests proximate to the wall bottom and in an active state rises toproximate to the water surface. The first three embodiments are configured to be drivenfrom the discharge or positive pressure side of a motor driven hydraulic pump. Thefourth embodiment (Figures 21-27) is configured to be driven from the intake or negativepressure (suction) side of such a pump.

Since the several embodiments have structural, functional, and operationalfeatures in common, several general comments will initially be presented with referenceto Figure 2, followed by a detailed discussion of each embodiment and its relatedFigures.

Figure 2 comprises a schematic diagram generally representing the primaryfunctional aspects of preferred systems in accordance with the invention. The systemof Figure 2 is shown as primarily including alevel control subsystem 14 and apropulsioncontrol subsystem 16. Thelevel control subsystem 14 is comprised of alevel modecontroller 14A capable of selectively defining either a first mode (water surface level) ora second mode (wall surface level). The mode defined bycontroller 14A is determinedby a user input 14B such as a manual switch or by an event sensor 14C in response toan event such as the expiration of a time interval or the cycling ofpump 10. Thus, forexample, in typical operation, the body 6 can be operated in the water surface mode fora one hour interval and then switched to the wall surface mode for a two hour interval.Alternatively, if the user desires that the body continue to operate in a particular mode,that mode can be set via user input 14B which overrides the mode toggling normallyproduced by event sensor 14C. The mode defined bycontroller 14A controls level control element 14D, e.g., a valve, which causes the body 6 to either ascend toproximate to the water surface or descend to proximate to the wall bottom.

Although embodiments of the invention can be implemented with the body'srest state being either proximate to the water surface or the wall bottom, the formerimplementation is presently preferred because when at rest, the body will beunobtrusively out of the way of swimmers.

Resting at the water surface can be achieved with sufficient buoyancy builtinto the body 6 so that it floats at rest, with weight low and buoyancy high so it is stable(right side up) at both the water surface and at the wall bottom. In order to clean theside and bottom portions of the wall surface, a sufficient hold down force must beproduced to keep the traction means 11 in adequate contact with the wall surface.

Resting on the wall bottom requires that the body 6 sink when it is notpowered. It must have its weight low and buoyancy high so it is stable on the watersurface and beneath it. The body 6 can be moved from the wall bottom to the watersurface by producing a vertical force component, e.g., by an appropriately directed waterflow, as will be discussed hereinafter, to push the body to the water surface.

To provide ease of installation and use, and to provide tolerance for themagnitude of the lifting force and the weight of the body when carrying different amountsof collected debris, and to aid stability when cleaning the water surface, it is presentlypreferred that the body lift weight and/or buoyancy out of the water as it rises. Thevertical lifting force is preferably developed in line with the center of gravity of the body6 at its operating height. It is desirable to position the weight and/or buoyancy thatcomes out of the water around and away from the center of gravity so that the body isstable on the water surface. For economy in production and shipping, the weight canbe provided by filling empty weight cavities in the body with water prior to operation.Such weight cavities can be filled via a tube which permits water to trickle from apressurized supply flow into each cavity during operation. A suction or negative pressure embodiment can use pump suction to draw a trickle of water through a smallhole in the bottom of each weight cavity.

Floating the body to the water surface can be accomplished by drawing airinto flotation cavities via a small tube. A suction cleaner can use pump suction to drawthe water out of the cavities and pull air in. In order to prevent air from entering the poolpump, a flexible plastic bag could be placed in each floatation cavity connected to theair tube. Water would never enter the air tubing or bags. As water is pulled out of thecavities, air is pulled into the bags; thus, floating the body. A pressure cleaner can usea pressurized water powered jet pump to draw water out of the cavities and/or pull orpump air into the cavities.

Themode controller 14A, in addition to controlling level control element14D, also controls cleaningcontrol element 14E. When in the water surface mode,element 14E, e.g.. a valve, causes skimming action and may additionally allow a whiphose to sweep the wall surface. When in the wall surface mode,element 14E. preferablycauses wall surface vacuuming and/or sweeping. General considerations for wall surfacecleaning can be summarized as follows:

POSITIVE PRESSURE CLEANER

1. The wall surface can be vacuumed using a source of pressurizedwater to power a liquid/liquid jet pump with a nozzle, a suction opening in close fluidcommunication with the wall surface to be cleaned, a tubular throat section. and aporous collection means (bag or container) coupled downstream ,of the throat sectionoutlet to collect debris: or

2. A jet pump can be used to evacuate a container containing a porouscollection means. having an opening in close fluid communication with the wall surfaceto be cleaned; or

3. A travelling body can scoop up debris in its path in a porouscollection means. Scooping performance can be enhanced by water jetted in thedirection of water flow relative to the body.

Water exiting from the body can provide thrust for propulsion and/orholding the device proximate the wall surface to be cleaned.

NEGATIVE PRESSURE CLEANER

1. Pump provided suction can draw water through a porous collectionmeans which may be positioned along the suction hose length in the fixed skimmer, inthe pump inlet, or within the pool cleaner body. The water and debris may pass througha turbine on its way to the collection means and pump inlet.

2. A suction powered travelling cleaner can scoop up debris in its pathin a porous collection means. Scooping performance can be enhanced by using pumpsuction or pump suction can draw water through a turbine to power a water flowgenerating device, such as a pump or propeller to increase the flow of water and debristhrough the porous collection means. Water exiting from such a device can providethrust for propulsion and/or holding the device proximate to the surface to be cleaned.

In order to provide the traction means 11, e.g., wheels, with sufficientfrictional contact with the wall surface to enable the body move with the desired degreeof directional consistency and to keep the sweep hose and/or the inlet to the debriscollection means in close proximity to the wall surface, it is desirable to produce a holddown force in a nominally vertical direction relative to the body 6 to urge the body, i.e.,traction means, against the wall surface. This hold down force can be provided by thesubmerged weight of the body if the vessel floor is relatively flat and the walls are not tobe climbed. Otherwise, water flow away from the body having a sufficient directionalcomponent perpendicular to the wall surface and/or the pressure differential caused by the surface being in close proximity to the debris path can provide a sufficient hold downforce.

General considerations for water surface cleaning can be summarized asfollows:

POSITIVE PRESSURE CLEANER

1. The water surface can be skimmed using a source of pressurizedwater to power a liquid/liquid jet pump which draws water and debris on the pool surfacepast a weir and a porous collection means; or

2. A source of pressurized water can power a nozzle which dischargesa water jet to entrain surface water and debris into a porous collection means; or

3. A travelling body can scoop up debris in its path in a porouscollection means. Scooping performance can be enhanced by entrainment caused bypressurized water jetted in the direction of water flow through the device.

Water exiting from the body can provide thrust for propulsion or lift.

NEGATIVE PRESSURE CLEANER

1. Pump powered suction can draw water and debris from the watersurface past a weir and a porous collection means; or

2. Pump powered suction can draw water from a chamber with an openor closed top and at least partially open side (at or just below the water surface forallowing the chamber to remain in flooded condition essentially up to the pool watersurface as a result of surface water and debris entering said chamber ) through a porousdebris collection means. The collection means can be in said chamber; or

3. Pump powered suction can draw water though a turbine to powera water flow generating device, such as a pump or propeller, etc., which can propelsurface water and debris through a porous debris collection means; or

4. Pump suction can propel a body to allow it to scoop up debris in itspath in a porous collection means. Scooping can be enhanced by using pump suctionor pump suction powered flow generating device to increase the flow of water and debristhrough the porous collection means.

Water exiting from the body can provide thrust for propulsion or lift.

Figure 2 also shows thepropulsion control subsystem 16 which includesapropulsion state controller 16A capable of selectively defining either a first state(normal) or a second state (backup). The state ofcontroller 16A is determined usuallyby anevent sensor 16B which can respond, for example, to the expiration of a timeinterval or to some other event such as the interruption of body motion. Thus, forexample, in typical operation, the body 6 will operate in the normal propulsion statebeing propelled in a forward direction for say two to five minutes, and then will beswitched to the backup state for perhaps 30 seconds, and then will be returned to thenormal state. These timing intervals are preferably separately optimized for each differentinstallation. By periodically switching to the backup state, the possibility of the bodygetting stuck behind some obstruction in the vessel is minimized. The normal togglingofcontroller 16A can be overridden by auser control 16C.

Thecontroller 16A controls adirection control element 16D,e.g. a valve,which develops a forward propulsion force during the normal state and a rearwardpropulsion force during the backup state. These forces include force componentsnominally horizontally oriented relative to the body 6 to enable the body to be propelledalong the water surface (during the water surface cleaning mode) and along the side andbottom positions of the wall (during the wall surface cleaning mode).

Anoptional steering mechanism 16E can be incorporated to vary thedirection of the forward and/or rearward propulsion force components to betterrandomize the body's travel path. This steering action can include the selective utilizationof side thrust water discharge.

More particularly, on both the water surface and wall surface, the bodyshould be able to travel forward, rearward, and to the left and to the right. This can beaccomplished by using contact with the pool contours to randomly redirect the body'stravel. Skewing the thrust direction to the axis of the cleaner can bias the travel path fora particular pool. However, to minimize the possibility of the cleaner getting stuck, e.g..in a corner, it is desirable that the cleaner periodically go backward. In addition, toassure complete cleaning coverage, it is preferable to be above to turn to the left and tothe right at predetermined intervals, as for example, by selectively discharging the sidethrust flows.

A timing assembly with a water flow powered turbine driving a gear traincan be designed to provide the desired travel path sequence. A variable flow control inthe water flow line to the turbine can be adjusted by the user to vary the timing cyclelength, e.g., longer for larger pools, shorter for smaller pools.

In order to alter the body travel direction, the thrust direction must bechanged. One way to do this is to move a rudder and/or a wheel, or a jet nozzle, or thedischarge of a jet pump, or redirecting water flow generated by a pump or a propellerrelative to the axis of the cleaner. Another way to is to have the timing assembly alterthe direction of the thrust by operating a steering valve or valves to create a sequenceof pressurized water discharge through differently directed nozzles and/or jet pumps.

A third steering method can use the output of the timing assembly tochange the directional relationship between the body and the hose supplying pressurizedwater or drawing water from the body. If the thrust direction relative to the body remainsfixed, and the supply hose has mass and stiffness, the torque created by the timingassembly will alter the direction of body travel. In this case, since the hose typically exitsfrom the body horizontally, the body can rotate less than 360 degrees relative to thehose in a first direction and then rotate a like amount in the opposite direction. This canbe accomplished by having rotation limits which cause the timing assembly output toreverse direction when said limits are contacted. The timing assembly output can be reversed by changing the turbine flow direction, by shifting gears, or by providing waterflow to a second turbine that rotates in the reverse direction.

General considerations regarding propulsion can be summarized as follows:

1. The body 6 can be propelled by various means including: turbinedriven traction means, walking mechanisms, oscillating mechanisms that causeintermittent water flow, imparting kinetic energy that causes motion, and thrust, which isa reactive force that moves the body in a direction opposite to the direction that waterexits from the body. All of these propelling means can be powered by either positive ornegative pump produced pressure. Thrust is the presently preferred technique becauseof its relative simplicity and its applicability to both surface and underwater propulsion.

Thrust can also create forces up, down, left, right and back for moving thedevice on the wall surface, on the water surface, and from one surface to the other.

POSITIVE PRESSURE CLEANER

1. Pressurized water can be jetted from a nozzle as a high velocity lowmass stream to create thrust in the opposite direction. The magnitude of the thrustproduced is a function of the water mass multiplied by its velocity.

2. The pressurized water powered nozzle can be part of a liquid/liquidjet pump which pumps pool water to create a much larger mass and lower velocity waterstream with greater thrust from the same water source.

NEGATIVE PRESSURE CLEANER

Pump suction is used to drive a flow generator to produce thrust A turbinedriven by water drawn through it by pump suction can drive oars, a swimmingmechanism, a pump, or a propeller which can move a large mass of pool water at lowvelocity and which can efficiently produce thrust for a given amount of energy input.

FIRST EMBODIMENT (Figures 3 - 8)

Attention is now directed to Figures 3 - 8 which depict afirst embodiment100 of the invention designed to be powered from the positive pressure side of a motordrivenhydraulic pump 10 via a hose 9 (Figures 1A, 1B). Theembodiment 100 iscomprised of aunitary body 102 which is primarily formed of upper and lower moldedsections 102U and 102L.Lower body section 102L supports threeparallel axles 104A,104B, 104C.Traction wheels 106A, 106B, 106C are mounted for free rotation onaxles104A, 104B, 104C respectively for tangentially engaging interior wall surface 8 (Figures1A, 1B). Thebody 102 defines an inlet supply fitting 110 which is coupled to the distalend ofsupply hose 9. The proximal end ofhose 9 is coupled to the pressure outlet ofpump 10.

The water flow supplied to inlet fitting 110 frompump 10 is distributed toa plurality of outlets carried bybody 102 by tubing 112 (best depicted in Figure 8,omitted from Figures 3 - 7 for clarity purposes). The plurality of outlets include:

1.	forward propulsion thrustjet	114
2.	rearward ("backup")propulsion thrust jet	116
3.	liftjet	118
4.	sweep hose	120
5.	timing nozzle	122
6.	vacuumjet pump nozzle	124
7.	skimmerjet pump nozzles	126

Thebody 102 is configured to define acollection path 130 for wall surfacedebris which extends from a vacuum inlet opening 132 (positioned betweenwheels 106Aand 106B close to the wall surface 8) and a vacuum discharge opening 134 (positionedproximate to the bodyrear portion 102R below the supply inlet fitting 110) The vacuumjet pump nozzle 124 discharges a high velocity flow into thepath 130 toward thedischarge opening 134. This action produces a suction at the vacuum inlet opening 132which draws water and debris from adjacent towall surface 8 and discharges it throughdischarge opening 134. The vertical component of the water drawn in through vacuuminlet opening 132, together with the weight of the unit, creates a hold down force actingto urge the traction wheels 106 against thewall surface 8.

Thebody 102 also defines acollection path 136 for surface water anddebris. More particularly, thebody 102 defines anopen skimmer chamber 138 havinganentrance 140 positioned betweensemi-cylindrical projections 142A, 142B. Aweir 143havingsides 144A, 144B is mounted adjacent to theentrance 140 positioned betweentheprojections 142A, 142B. Theweir 143 is mounted for reciprocal vertical motionrelative to the body so that when the body is floating proximate to the water surface,surface water will flow or spill over the weir sides 144A, 144B into theopen skimmerchamber 138. Thepath 136 extends from theentrance 140, through thechamber 138,to adischarge opening 146 positioned adjacent to discharge opening 134 proximate tothe bodyrear portion 102R below the supply inlet fitting 110. The skimmerjet pumpnozzles 126 discharges a high velocity flow intopath 136 toward thedischarge opening146. This action produces a suction which draws water and debris fromchamber 138and discharges it throughdischarge opening 146.

Theopen mouth 150 of a debris collection container orbag 152 isdetachably mounted arounddischarge opening 134 and 146. Thebag 152 is preferablyformed of water permeable material for the side andbottom panels 154 to permit thewater from thedischarge openings 134, 146 to flow through the bag. The top andrearpanels 156, 158 are preferably formed of impermeable material to discourage an upwardflow of water out of thebag 152 which would create an unwanted downward thrust.

Each of theaforementioned projections 142A, 142B is defined by asemi-cylindricalwall 158, which together with alid 160, encloses acavity 162. As will beshown hereinafter, eachcavity 162 fills with water to the level of itslid 160. Eachlid 160has anoverflow hole 164. The water filled cavities provide ballast for stability near thewater surface. The body can be thrust to the water surface by a downward flow exitingfrom thelift jet outlet 118. When the body reaches the ambient air/water surface boundary, the weight of water in the twocavities 162 being lifted above the water surfacereaches equilibrium with the thrust produced byjet 118 to establish an operating levelappropriate for skimming action byweirs 143.

The bodylower section 102L preferably carries one ormore guard wheels165 mounted for rotation on a vertical axis for facilitating movement around obstructions.

Particular reference is now called to Figure 8 which schematically depictsthe water flow through theembodiment 100 structurally depicted in Figures 3-7. Notethat water entering theinlet 110 initially fillsweight cavities 162 and may exit throughoverflow holes 164. The water enteringwater inlet 110 is also directed to theaforementioned timing nozzle 122, preferably via anadjustable flow control 168 fordriving aturbine 170. Theturbine 170 forms part of atiming assembly 171 whichincludes agear train 172 controlling asteering valve 174. The steeringvalve 174 candefine either the aforementioned normal propulsion state or back-up propulsion state.When thesteering valve 174 is in the back-up state, water supplied toport 175 isdischarged via the rearward propulsion thrustjet 116 to move the body rearwardly.When thesteering valve 174 is in its normal state, the water supplied toport 175 exitsviaforward outlet port 176. The flow fromport 176 is supplied to supplyport 177 andcontrolport 178 of an alternatinglevel control valve 179. Thevalve 179 is capable ofselectively defining either a wall surface cleaning mode, or a water surface cleaningmode. When in the wall surface cleaning mode, the water flow to supplyport 177 isdischarged viaoutlet port 180 to the vacuumjet pump nozzle 124, the forwardpropulsion thrustjet 114, and thesweep hose outlet 120. Theoutlet 120 is preferablyconnected to anadjustable flow control 181 which supplies one end of a whip or sweephose 182. When thelevel control valve 179 is in the water surface cleaning mode, thewater flow supplied fromport 177 tovalve 179 is directed viaoutlet port 184 to thelift jet118 and to a pair of skimmerjet pump nozzles 126. Although not represented in Figure8, a water flow can also be provided to thesweep hose 182 in the water surface cleaning mode to enable thesweep hose 182 to hang below thebody 102 and sweep against thewall surface, e,g, steps.

The initiation of a flow fromoutlet port 176 to controlport 178 is used asthe event to switch the state oflevel control valve 179. Thus, for example, each time thesteering valve 174 initiates a flow out ofport 176, it will switch the mode from wall surfacecleaning to water surface cleaning or vice versa. Different events could, of course, beused to togglelevel control valve 179. Additionally, it can be recalled from Figure 2 thatin some installations, it may be desirable to incorporate a user input control for settingor overriding the event sensor mechanism which normally controls thevalve 179 duringautomatic operation.

In typical automatic operation of theembodiment 100, thebody 102 will bepropelled forwardly along thewall surface 8 by the discharge from directionallyadjustable jet 114 for a certain period of time, e.g. two to five minutes. Its direction willbe randomly influenced by the contours of the vessel, the drag ofsupply hose 9, theinfluence ofsweep hose 182, etc. After a certain interval, the steeringvalve 174 willchange state and the unit will backup as a consequence of discharge from the rearwardpropulsion thrustjet 116. After a further interval, e.g., thirty seconds, thevalve 174 willchange state.

SECOND EMBODIMENT (Figures 9 - 15)

Attention is now directed to Figures 9 - 15 which depict asecondembodiment 200 of the invention designed to be powered from the positive pressure sideof a motor drivenhydraulic pump 10 via a hose 9 (Figures 1A, 1B). Theembodiment200 is comprised of aunitary body 202 which is primarily formed of upper and lowermoldedsections 202U and 202L. Lower body section 202L supports three horizontallyorientedparallel axles 204 on whichtraction wheels 206A, 206B, 206C are mounted forfree rotation for tangentially engaging interior wall surface 8 (Figures 1A, 1B). Thebody 202 defines an inlet supply fitting 210 which is coupled to the distal end ofsupply hose9. The proximal end ofhose 9 is coupled to the pressure outlet ofpump 10.

The water flow supplied to inlet fitting 210 frompump 10 is distributed toa plurality of outlets carried bybody 202 by tubing 212 (best depicted in Figure 15,omitted from Figures 9 - 14 for clarity purposes). The plurality of outlets include:

1.	forward thrustjet	214
2.	rearward ("backup") thrustjet	216
3.	thrust/lift jet	218
4.	sweep hose	220
5.	timing nozzle	222
6.	vacuumjet pump nozzle	224
7.	surface cleaning nozzle	226
8.	left jet	228
9.	right jet	230

Thebody 202 is configured to define a first collection path for wall surfacedebris which extends from a vacuum inlet opening 232 (positioned betweenwheels 206Aand 206B close to the wall surface 8) and avacuum discharge opening 234. Thevacuumjet pump nozzle 224 discharges a high velocity flow into the first path toward thedischarge opening 234. This action produces a suction at the vacuum inlet opening 232which draws water and debris from adjacent towall surface 8 and discharges it throughdischarge opening 234. The vertical component of the water flowing through first path;together with the weight of the unit. creates a hold down force acting to urge the tractionwheels 206 against thewall surface 8.

Thebody 202 also defines acollection path 236 for surface water anddebris. More particularly, theupper body section 202 defines a horizontal shelf surfacehavingupstanding side walls 240A. 240B and a centralupstanding fin 242. As the bodymoves forward through the water pool near the surface, surface water and debris arescooped up moving rearwardly oversurface 238 betweenside walls 240A, 240B. Thecollection path 236 extends from theleading edge 243 ofsurface 238 to a trailingedge244. Thesurface 238 defines acutout 246 below which the aforementionedsurfacecleaning nozzle 226 is mounted. Thenozzle 226 discharges a flow throughcutout 246intopath 236 toward the trailingedge 244. This action facilitates the flow of water anddebris oversurface 238 from the leading to the trailing edge thereof.

Note also that discharge opening 234 ofcollection path 230 also opensontoshelf 238 viacutout 248 just upstream from the trailingedge 244.

Theopen mouth 250 of a debris collection container orbag 252 isdetachably mounted adjacent to trailingedge 244 between upstanding sidewalls 240A,240B. Thebag 252 is preferably formed of water permeable material to permit waterflowing rearwardly from theshelf 238 to flow through the bag.

The aforementionedupstanding walls 240A, 240B, as well ascentral fin 242each enclose acavity 262. As will be shown hereinafter, eachcavity 262 fills with waterto the level of anoverflow hole 264. The water filled cavities provide ballast for stabilitynear the water surface. The body can be thrust to the water surface by a downward flowexiting from the thrust/lift jet outlet 218. When the body reaches the ambient air/watersurface boundary, the weight of water in thecavities 262 being lifted above the watersurface reaches equilibrium with the thrust produced byjet 218 to establish an operatinglevel appropriate for skimming action overshelf 238.

Thebody 202 preferably carries a plurality ofguard rollers 265 eachmounted for rotation about a vertical axis. Therollers 265 are distributed around theperiphery 266 ofbody 202 and facilitate the body's movement around obstructions.

Particular reference is now called to Figure 15 which schematically depictsthe water flow through theembodiment 200 structurally depicted in Figures 8-12. Notethat water entering theinlet 210 initially fillsweight cavities 262 and is also directed totheaforementioned timing nozzle 222, preferably via anadjustable flow control 268 fordriving aturbine 270. Theturbine 270 forms part of a timing assembly 271 whichincludes agear train 272 controlling asteering valve 274. The steeringvalve 274 can define either the aforementioned normal propulsion state or back-up propulsion state.When thesteering valve 274 is in the back-up state, water supplied toport 275 isdischarged via the rearward propulsion thrustjet 216 to move the body rearwardly.Additionally, water can be selectively discharged through left andright jets 228, 230 tofacilitate the body freeing itself from any encountered obstructions. These same sidethrust jets are also preferably used in the normal propulsion state to better randomizetravel and escape obstructions.

When thesteering valve 274 is in its normal state, the water supplied toport275 exits viaforward outlet port 276. The flow fromport 276 is supplied to supplyport277 of an alternatinglevel control valve 279.

Thevalve 279 is capable of selectively defining either a wall surfacecleaning mode, or a water surface cleaning mode. The valve mode is switchedwhenever a flow to controlport 278 is initiated. As shown in Figure 15, the flow tocontrolport 278 is derived fromsupply inlet 210. Accordingly, whenever thepump 10supplyinginlet 210 starts up, the mode ofvalve 279 changes.

Although Figure 15 depicts the initiation of a flow to controlport 278 frominlet 210 as the triggering event to switch thelevel control valve 279 mode, other eventscould, of course, be used to togglevalve 279. Moreover, it should be recalled fromFigure 2 that it maybe desirable to incorporate a user input control for setting oroverriding the event sensor which normally controls the automatic operation ofvalve 279.

When in the wall surface cleaning mode, the water flow to supplyport 277is discharged viaoutlet port 280 to the vacuumjet pump nozzle 224, the forwardpropulsion thrust jet 214 (preferably directionally adjustable), and thesweep hose outlet220. Anadjustable flow control 281 is preferably connected just upstream of thesweephose outlet 220. When thelevel control valve 279 is in the water surface cleaning mode,the water flow supplied fromport 277 tovalve 279 is directed viaoutlet port 284 to thethrust/lift jet 218 and to the aforementionedsurface cleaning nozzle 226. Although notrepresented in Figure 8, a water flow can also be provided to thesweep hose 220 in the water surface cleaning mode to enable the sweep hose outlet to hang below thebody202 to sweep against portions of the wall surface.

In typical automatic operation of theembodiment 200, thebody 202 will bepropelled along thewall surface 8 by the discharge fromthrust jet 214 for a certainperiod of time, e.g., two to five minutes. Its direction will be randomly influenced by thecontours of the vessel, the drag ofsupply hose 9, the influence ofsweep hose 282, etc.When the timing assembly changes thesteering valve 274 state, the unit will backup asa consequence of discharge from the rearward propulsion thrustjet 216 for a certaininterval, e.g., thirty seconds, before resuming its normal state. As represented in Figure15, the alternatingvalve 279 will periodically switch modes independently of timingassembly 271 in response to a triggering event such as the cycling ofpump 10.

The following Table I list the primary characteristics of a typical unitcorresponding to embodiment 200:

Types of pools cleaned	All inground and above ground pools
Power source	Booster pump and/or pool pump
Wheels - number /diameter	3 wheels 101,6 mm (4")diameter
Debris collected in	Mesh bag
Wall Cleaning	Vacuum & sweeps
Vacuum jets	1
Vacuumminimum diameter	50,8 mm (2")
Vacuum opening width	180,34 mm (7.1")
Sweeping	Whip hose
Propulsion
	1 thrust jet
Wall surface travel path	Forward and left, straight, right, straight and random. Back and up to the left and right.
Water surface cleaning?	Skims
Surface cleaning jets	1
Opening width	241,3 mm (9.5")
Debriscollection bag opening	76,2 mm (3")high x 12,7 mm (5")wide
Propulsion
	1 thrust/lift jet
Water surface travel path	Forward and left, straight. right. straight and random. Back and down to the left and right

THIRD EMBODIMENT (Figures 16 - 20)

Attention is now directed to Figures 16 - 20 which depict athirdembodiment 300 of the invention designed to be powered from the positive pressure sideof a motor drivehydraulic pump 10 via a hose 9 (Figures 1A, 1B). Theembodiment 300is comprised of aunitary body 302 supported on threetraction wheels 306A, 306B, 306Cmounted for free rotation on horizontal axles for tangentially engaginginterior wallsurface 8. The traction wheels are arranged to essentially orient the nose or front 302Fof the body down about 15 degrees relative to the rear 302R of the body, as shown inFigure 16.

Thebody 302 is provided with an inlet supply fitting 310 which is coupledto the distal end ofsupply hose 9. The proximal end ofhose 9 is coupled to pressureoutlet ofpump 10.

The water flow supplied to inlet fitting 310 frompump 10 is distributed toa plurality of outlets carried bybody 302 by tubing 312 (best depicted in figure 20,omitted from figures 16 - 19 for clarity purposes). The plurality of outlets include:

1.	forward propulsion thrust/surface cleaning jets	314
2.	rearward ("backup") thrustjet	316
3.	liftjet	318
4.	sweep hose	320
5.	timing nozzle	322
6.	vacuumjet pump nozzle	324
7.	left jet	326
8.	right jet	328

Thebody 302 is configured to define acollection path 330 for wall surfacedebris which extends from a vacuum inlet opening 332 (positioned betweenwheels 306Aand 306B close to the wall surface 8), and avacuum discharge opening 334. Thevacuumjet pump nozzle 324 discharges a high velocity flow into thepath 330 toward thedischarge opening 334. This action produces a suction at the vacuum inlet opening 332which draws water and debris from adjacent towall surface 8 and discharges it throughdischarge opening 334. The vertical component of the water flow throughpath 330,together with the weight of the unit, creates a hold down force acting to urge the tractionwheels 306 against thewall surface 8.

Thebody 302 also defines acollection path 336 for surface water anddebris. More particularly, thebody 302 defines ahorizontal shelf surface 338 havingupstanding side walls 340A, 3408. As the body moves forward through the water poolnear the water surface, surface water and debris are scooped up moving rearwardly oversurface 338 betweenside walls 340A and 340B. Thecollection path 336 extends fromtheleading edge 343 ofsurface 338 to a trailingedge 344. Thesurface 338 defines acutout 348 aligned with theaforementioned discharge opening 334, just upstream fromtheshelf trailing edge 344.

Theopen mouth 350 of a debris collection container orbag 352 isdetachably mounted to thebody 302 proximate to the trailingedge 344 and spacedabove thesurface 338 as is best depicted in Figure 16. Thebag 352 is preferablyformed of water permeable material to permit water flow therethrough.

The aforementionedupstanding walls 340A, 340B, each enclose acavity362. As would be shown hereinafter, eachcavity 362 fills with water to the level of anoverflow hole 364. The water filled cavities provide ballast stability when the body is atthe water surface. The body can be thrust to the water surface by a downward flowexiting fromlift jet 318. Thejet 318 is able to lift the body to a level where the weight ofwater in thecavities 362 being lifted above the water surface reaches equilibrium with thethrust afforded byjet 318.

The body 303 preferably carries a plurally ofguard rollers 365 eachmounted for rotation about a vertical axis. Therollers 365 are distributed around theperiphery 366 ofbody 302 and facilitate the body's movement around obstructions.

Particular reference is now called to Figure 20 which schematically depictswater flow to theembodiment 300 structurally depicted in Figures 16 - 19. Note that thewater entering thewater inlet 310 initially fillsweight cavities 362 and is also directed totheaforementioned timing nozzle 322, preferably via anadjustable flow control 368 fordriving aturbine 370. Theturbine 370 forms part of atiming assembly 371 whichincludes agear train 372 controlling asteering valve 374 which can define either anormal propulsion state or a backup propulsion state. When the backup state is defined,water supplied toport 375 is discharged via the rearward propulsion thrustjet 316 tomove the body rearwardly and/or to left andright jets 326, 328 to produce side thrust forfreeing the body from any encountered obstructions. These same side thrust jets arealso preferably used in the normal propulsion state to better randomize travel and escapeobstructions.

When thesteering valve 374 is in its normal state, the water supplied toport375 exits viaforward outlet port 376. The flow fromport 376 is supplied to supplyport377 of an alternatinglevel control valve 379. Thevalve 379 is capable of selectivelydefining either a wall surface cleaning mode or a water surface cleaning mode. Valvemode is switched when ever a flow to controlport 378 is initiated. As shown in Figure20, the flow to controlport 378 is derived fromsupply inlet 310. Accordingly, wheneverthepump 10 starts up, the mode ofvalve 379 is changed.

Although Figure 20 depicts the initiation of a flow to controlport 378 frominlet 310 as the triggering event to switch thecontrol valve 379 mode, other events could,of course, be used to togglevalve 379. Moreover, it should be recalled from Figure 2 that it is appropriate to incorporate an input control for enabling a user to set or overridethe normal control ofvalve 379.

Note in Figure 20 that water is supplied to the thrust/surface cleaning jets314 during the normal state of the steeringvalves 375 regardless of the mode definedby alternatingvalve 379. Thus, when the system is in the wall surface cleaning mode,the body is forwardly propelled by the thrust/surface cleaning jets 314 and a componentof the vacuumingjet pump 324. During the wall surface cleaning mode the body will beoriented nose down as shown in Figure 16. The bottom of thecollection bag 352 islocated above the shelf surface 338 (Figure 16) and, therefore, most of the waterdischarged from the thrust/surface cleaning jets 314 clings to thesurface 338 and isdischarged without passing through the collection bag. This results in greater propulsionand hold down thrust from thesejets 314 then if the water were to pass through the bagmaterial and debris therein. As thebody 302 traverses the wall surface, debris iscollected in the bag as a consequence of the action of vacuumjet pump nozzle 324.Further wall surface cleaning occurs as a consequence of the sweeping action ofwhiphose 382.

When thevalve 379 defines the water surface cleaning, thelift jet 318thrusts the body to the water surface to an equilibrium level at which the weight of thebody, including the water filledcavities 362, above the water surface equals the verticalforce component oflift jet 318. When at the water surface, the body assumes a morehorizontal attitude so that as it moves forward along the water surface, water and floatingdebris will flow into thebag 352 abovesurface 338.

In typical automatic operation of theembodiment 300, thebody 302 movesforward for two to five minutes cleaning either the wall surface or the water surface withits direction randomly influenced by objects it encounters and by water periodically jettedout of the left jet for about 30 seconds, and subsequently out of the right jet for about30 seconds. Intervals of straight travel occur before, between, and after the side thrustintervals. For example, each two to five minutes thebody 302 can be caused to move rearwardly for about 30 seconds by discharging a flow through the backup thrustjet 316,which can optionally occur in conjunction with one of the side thrustsjets 326, 328. Forexample, the timing assembly steering valve can be programmed to provide threeperiods of alternating side thrusts during each major cycle with the side thrust duringsequential backup intervals alternating.

As depicted in Figure 16, thelift jet 318 optionally be configured as ajetpump 318J to increase water flow, thrust and efficiency. Similarly, a jet pump could alsobe substituted for any of the other aforementioned jets, such asright jet pump 328J(Figure 17).

FOURTH EMBODIMENT (Figures 21 -27)

Attention is now directed to Figures 21 - 27 which depict afourthembodiment 400 of the invention designed to be powered from the negative pressure(suction) side of a motor drivenhydraulic pump 10 via a hose 9 (Figures 1A, 1B) whichhose is preferably specially configured as is depicted in Figure 23. Theembodiment 400is comprised of aunitary body 402 which is primarily formed of upper and lower moldedsections 402U and 402L.Lower body section 402L supports threetraction wheels 406A,406B, 406C mounted for free rotation on horizontal axles for tangentially engaginginteriorwall surface 8. As shown in Figure 23, the traction wheels are arranged on the body sothat when resting on a horizontal surface, the nose or front 402F of the body will beinclined downwardly from the rear 402R of the body by about 18 degrees. Thebody 402is provided with an outlet supply fitting 410 which is mounted in the free end ofswivelarm 411 and coupled to the distal end ofsupply hose 9. The proximal end ofhose 9 iscoupled to the suction side ofpump 10. The pump suction applied to fitting 410 iscoupled viaarm 411 to various inlets in thebody 402 including:

1.	vacuuminginlet	420
2.	timingassembly timing inlet	422
3.	alternatingvalve inlet	424

As will be seen hereinafter, pump suction is able to pull water in through these inlets forflow through outlet fitting 410 to thepump 10 suction side.

Theupper body section 402U is comprised primarily of a horizontallyorientedsurface 438 having a pair ofupstanding side walls 440A and 440B. Thesurface438 defines aleading edge 443 and a trailingedge 444. Theopen mouth 450 of a watersurface debris collection container orbag 452 is detachably mounted to thebody 402behind theleading edge 443 above thesurface 438. Thebag 452 is preferably formedof water permeable material to permit water flow therethrough.

The aforementionedupstanding walls 440A, 440B, each enclose acavity462 containing flaccidplastic bag 464. Anair tube 466 communicates with theflaccidbag 464 and extends throughhose 9 as depicted in Figure 23 to atmospheric air abovethe water surface, e.g., in the pools built-in wall skimmer (not shown). Thewater cavity462 communicates with atube 468 which is connected to theinlet port 424 of analternatingvalve 470. As is shown in Figure 27, the outlet side of the alternatingvalve470 is connected via aport 472 to the suction outlet fitting 410. Additionally, thealternating valve control port is similarly connected to suction fitting 410.

Theaforementioned vacuum inlet 420 shown in Figure 23 opens into avacuumingpath 476 which includes aturbine 478. The vacuumingpath 476 dischargesinto the suction outlet fitting 410 viaswivel arm 411. Thus, when water is pulled inthrough the vacuuminginlet 420 by the pump suction applied to fitting 410, it will movepast and driveturbine 478. Athrust propeller 480 is mounted to the shaft ofturbine 478for propelling the body along either the wall surface or on the water surface.

Thewater inlet 422 drives aturbine 482 which is coupled to asteering geartrain 484 of atiming assembly 485. This gear train is coupled to thehub 486 ofswivelarm 411 for rotating the hub arm aroundpost 487.

The alternatingvalve 470 is capable of toggling between a water surfacecleaning mode and a wall surface cleaning mode. Switching of the alternating valvemode is in response to the initiation of flow through the control port 474. Port 474 is coupled via fitting 410 to pump suction viahose 9 and thus in the configuration shown,thevalve 470 mode changes whenever the pump starts up.

For water surface cleaning, the alternatingvalve 470 directs the suctionavailable at fitting 410 to draw water out of thecavities 462. This permits theplastic bag464 within each cavity to pull air in viatube 466 which, as has been noted, is routedthroughsupply hose 9 to atmospheric air. As thebags 464 fill with air, the buoyancy ofthe body increases and causes the body to float to the water surface with great stability.As thepropeller 480 propels the body forward, water and floating debris are scoopedfrom the water surface aboveshelf surface 438 and guided into thepermeable collectionbag 452 via theopen mouth 450.

When the mode of alternatingvalve 470 changes to the wall surfacecleaning mode, it will stop drawing water out of thecavities 462 and allow water to flowinto the cavities causing theinternal bags 464 to collapse and pushing the air therein outthrough thetube 466. This action causes the body to lose buoyancy and sink to thepool bottom for operation in the wall surface cleaning mode. In the wall surface cleaningmode, the body will be propelled along the wall surface by the action ofpropeller 480driven byturbine 478. Theturbine 478 is driven by the flow of water drawn intovacuuminginlet 420 as a consequence of the suction applied topath 476 viafitting 410.Debris drawn into the vacuuminginlet 420 during the wall surface cleaning mode will becarried through to the pool filter or can be collected by an inline collection containerlocated somewhere along the length ofsupply hose 9 or in the conventional built in wallskimmer.

In normal automatic operation, thebody 402 is propelled forwardly bypropeller 48 in both the wall surface cleaning mode and the water surface cleaningmode. The direction of movement of the body will be randomly influenced by that whichit encounters and by the rotation of the body relative to theswivel arm 411. Thearm 411is reciprocally rotationally driven aroundpost 487 by the action of thesteering gear train484. Preferably, thearm 411 can rotate approximately 270 degrees in one direction over a one to four minute interval. The arm then is driven in the opposite direction for asimilar period. The two states of directional rotation, i.e., clockwise and counterclockwiseare controlled by thetiming assembly 485.

The following Table II lists the primary characteristics of a typical unitcorresponding to embodiment 400:

Types of pools Cleaned	All Inground and Aboveground Pools
Power source	Pool Pump
Wheels - number /diameter	3 wheels 101.6 mm (4") diameter
Wall cleaning	Vacuum and sweep
Vacuum minimum diameter	34,325 mm (1 3/8")
Vacuum opening width	177,8 mm (7")
Debris collected in	Inline container
Propulsion	Turbine driven propeller
Wallsurface travel path	270 degrees clockwise & 270 degrees counterclockwise with pauses as desired
Water surface cleaning	Skims
Debris collected in	Mesh bag
Debriscollection bag opening	76,2 mm (3")high x 203,2 mm (8") wide
Propulsion	Turbine driving a propeller
Lift	Air from above water in skimmer box
Wall surface travel path	Same as on pool bottom

From the foregoing, it should now be appreciated that a method and apparatushas been disclosed for automatically cleaning a water pool characterized by the use ofa unitary body structure which travels between the wall surface and water surface. Thebody structure is preferably compactly dimensioned, i.e., within a 0,6096 m x 0,6096 m x 0,6096 m (2' x 2' x 2') envelope,and has hydrodynamically shaped exterior surfaces, which can in part be defined by finsor wings, enabling it to move efficiently through the water. More particularly, the bodys exterior contour is preferably shaped to facilitate its travel underwater adjacent to the wallsurface, its travel from the wall surface to the water surface, its travel from the wallsurface to the water surface, and its travel along the water surface. For this purpose, thebody exterior can be contoured so that (1) its travel along the wall surface produces ahold down force component urging its traction means more tightly against the wallsurface, (2) its travel proximate to the water surface produces a lift force component tohelp maintain the body at the water surface and (3) its travel between the wall surfaceand water surface generates forces appropriate to maintaining the correct attitude of thebody and efficiently employing the source energy.

Although the present invention has been described in detail with referenceonly to a few specific embodiments, those of ordinary skill in the art will readilyappreciate that various modifications can be made without departing from thescope of the invention as defined by the appended claims.

Claims (17)

1. Apparatus for cleaning the surface of a water pool (1) contained in a vesseldefined by a wall (3) having bottom (4) and side portions (5), said apparatuscomprising:

   a unitary heavier-than-water or lighter-than-water body (6) capable of beingimmersed in said water pool (1),

   a level control subsystem (14);

   wherein, when said body (6) is heavier than water, said level controlsubsystem (14) comprises means (9,10) for supplying a fluid flow to saidbody (6) to lift said body (6) to proximate to said water surface (7);
   wherein, when said body (6) is lighter than water, said level controlsubsystem (14) defines either a quiescent state for permitting said body tofloat proximate to said water surface (7) or an active state for producing avertical force component for holding said body (6) proximate to said wallsurface (4,5);
   and further comprising a water surface inlet carried by said body (6)configured to receive pool water from adjacent to said water surface,characterized by a propulsion control subsystem (16) for moving said body(6) along a path adjacent to said water surface (7).
2. The apparatus of claim 1 further including means (152) for removing debrisfrom water received via said water surface inlet.
3. The apparatus of claim 2 wherein said means for removing debris includes awater permeable debris container (152) for retaining debris removed fromwater received via said water surface inlet.
4. The apparatus of claim 1 to 3, wherein the level control subsystem (14)responsive to said fluid flow produces a vertical force to selectively place saidbody either proximate to said water surface (7) or proximate to said wallsurface (4,5) below said water surface;
   and wherein the propulsion control subsystem (16) is responsive to said fluidflow for selectively moving said body (6) either along a path adjacent to saidwater surface (7) for collecting pool water through said inlet from adjacent tosaid water surface (7) or along a path adjacent to said wall surface (4,5) forcollecting pool water through said inlet from adjacent to said wall surface(4,5).
5. The apparatus of claim 4 wherein said body (6) is heavier than water; andwherein
   said level control subsystem (14) defines either a quiescent state forpermitting said body (6) to sink to proximate to said wall surface (4,5) or anactive state for producing a vertical force component for lifting said body (6)to proximate to said water surface (7).
6. The apparatus of claim 1 to 5,whereby said level control system (14) comprises automatic controlmeans and a level control element (14D) and whereby theautomatic control meansselectively switches the mode defined by said level control element(14D);
   means for maintaining said body adjacent to said interior wall surface (4,5)when said level control element (14D) is in said wall surface cleaning mode;
   means for supporting said body proximate to said water surface (7) whensaid level control element (14D) is in said water surface cleaning mode;
   and means (152) for collecting pool water through said inlet from adjacent tosaid interior wall surface (4,5) when said level control element (14D) is in said wall surface cleaning mode and adjacent to said water surface (7) when saidlevel control element (14D) is in said water surface cleaning mode.
7. The apparatus of claim 6 wherein said body (6) is comprised of upper (6U)and lower portions (6L) spaced in a nominally vertical direction and front (6F)and rear portions (6R) spaced in a nominally horizontal direction; andwherein
   said means for maintaining said body adjacent said interior wall surface (4,5)comprises means for producing a force component in said nominally verticaldirection toward said interior wall surface.
8. The apparatus of claim 7 wherein said means for producing a forcecomponent in said nominally vertical direction includes means for creating awater outflow from said body (6) having a component oriented in a directionfrom said body lower portion (6L) toward said body upper portion (6U).
9. The apparatus of claim 6 further including a mode control device (14A) forselectively switching said level control element (14D).
10. The apparatus of claim 9 further including an event sensor (14C); andwherein
    said mode control device (14A) is responsive to said event sensor (14C) forswitching said level control element (14D) from one of said modes to theother of said modes.
11. The apparatus of claim 10 further including an override mechanism (14B) forpreventing said level control element (14D) from switching modes.
12. The apparatus of claim 9 further including a pump (10) actuatable to create afluid flow to said body (6); and wherein
    said mode control device is responsive to the actuation of said pump (10) forswitching said level control element from one of said modes to the other ofsaid modes.
13. The apparatus of claim 12 further including an override mechanism (14B) forpreventing said level control element (14D) from switching modes.
14. A method of cleaning both the interior wall surface (4,5) of an open containerand the water surface (7) of a water pool (1) contained therein, said methodcomprising:

    placing a body (6) in said water pool (1);

    supplying a fluid flow to said body (6) for producing a vertical force thereon toselectively move said body (6) to either proximate to said water surface (7) orproximate to said wall surface (4,5) below said water surface(7);

    urging said body (6) against said interior wall surface (4,5) when said body(6) is proximate to said wall surface (4,5);

    supporting said body (6) proximate to said water surface (7) when said body(6) is proximate to said water surface (7); and

    collecting pool water from adjacent to said water surface (7) when said body(6) is proximate to said water surface (7) and adjacent to said wall surface(4,5) when said body (6) is proximate to said wall surface (4,5).
15. The method of claim 14 further including:

    propelling said body (6) along a path adjacent to said wall surface (4,5) forcleaning said wall surface (4,5).
16. The method of claim 15 further including:

    propelling said body (6) along a path adjacent to said water surface (7) forcleaning said water surface (7).
17. The method of claim 14 further including removing debris from said collectedpool water.

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