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CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a division of and claims priority to an application entitled HYDRAULIC SUCTION FUSE FOR SWIMMING POOL, filed Apr. 16, 2003, assigned Ser. No. 10/417,872, which application is directed to an invention made by the present inventors and assigned to the present assignee. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Typically, swimming pools include a pump for drawing water from a drain at the bottom of a pool through a debris collection trap to a filter from which the water is returned to the pool. Most pools also include a skimmer in fluid communication with the debris collection trap. A typical debris collection trap of this type is illustrated and described in U.S. Pat. No. 5,265,631, which patent describes an invention by the present inventor and is assigned the present assignee.  
         [0003]     The drain at the bottom of a swimming pool can pose a safety hazard to an occupant of the pool, particularly a young child or a person of limited physical strength. As water is drawn through the drain by the pump, a suction force exists at the surface of the drain. Should a user of a pool inadvertently cover the drain with a part of his/her body, the suction force will tend to retain the user against the drain unless the user has sufficient strength to push away from the drain. If such strength is not available or if the user panics, drowning may result. Furthermore, even if the user is capable of pushing away from the drain, injury of more or less seriousness may result.  
         [0004]     To overcome the potential for injury or drowning due to being drawn against and retained by a swimming pool drain, various devices have been developed over the years to break the pump suction in the event a high suction condition is sensed due to covering or at least restricting the flow of water through the drain. Some of these devices introduce air to the inlet side of the pump in response to the sensed high suction condition, which results in loss of pump prime. Other devices interrupt the power source to the pump and the pump ceases to operate. There are also devices which provide for a conduit open to the atmosphere that is submerged a given distance below the pool water level and connected to the pump inlet to introduce air if a predetermined level of suction is sensed.  
         [0005]     There are numerous problems attendant existing prior art devices, which problems will be summarized below. Many of the devices are very expensive and have many moving parts. Some of the devices provide false signals triggered by partly or wholly filled pump and/or skimmer baskets. Installation of some devices may require several feet of excavation for installation purposes which render them expensive and the resulting deterrent may preclude installation. Depending upon the system installed, the pump may be damaged upon actuation with the resulting attendant problems of expense and loss of use of the swimming pool.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     The present invention is a hydraulic suction fuse used as part of a debris collection trap, such as described in U.S. Pat. No. 5,265,631, and provides a very economical and dependable safety valve to terminate the suction force that is present at a swimming pool drain should the drain become covered by a body part of a person in the swimming pool. The fuse is mounted in the lid of the debris collection trap. It is a mechanical device, with or without an automatic resetting feature responsive to an above expected suction force within the debris collection trap. Upon existence of the above average suction force, the lid is vented to permit inflow of any water present above the lid and thereafter ambient the air. The presence of the air within the debris collection trap will cause cessation of any suction pressure at the drain and at any connected skimmer. When the drain becomes uncovered, water will flow into the debris collection trap by gravity. Upon fill of the debris collection trap with water, the fuse may close automatically or it may be manually reset, depending upon which type of fuse is used. Thereafter, normal operation will resume.  
         [0007]     It is therefore a primary object of the present invention to provide a cessation of a suction force at the drain of a swimming pool if it becomes covered.  
         [0008]     Another object of the present invention is to provide a cessation of a suction force at the drain of a swimming pool should it become covered by a body part of an occupant of the swimming pool.  
         [0009]     Yet another object of the present invention is to provide a hydraulic suction fuse for preventing an excessive suction force at the drain of a swimming pool.  
         [0010]     Still another object of the present invention is to provide a safety valve for preventing a user of a swimming pool from becoming trapped by the suction force at the drain of the swimming pool.  
         [0011]     A further object of the present invention is to provide an automatically resettable hydraulic suction fuse for preventing excessive suction force at the drain of a swimming pool.  
         [0012]     Another object of the present invention is to provide a manually resettable hydraulic suction fuse for preventing excessive suction at the drain of a swimming pool.  
         [0013]     Yet another object of the present invention is to provide a safety valve for terminating flow through a swimming pool drain upon clogging of the drain.  
         [0014]     A still further object of the present invention is to provide an inexpensive hydraulic suction fuse for use with the drain of a swimming pool.  
         [0015]     A yet further object of the present invention is to provide a method for preventing an excessive suction force at the drain of a swimming pool.  
         [0016]     A yet further object of the present invention is to provide a method for automatically or manually resetting a safety valve actuated due to an excessive suction force at the drain of a swimming pool.  
         [0017]     A yet further object of the present invention is to provide a method and apparatus for releasing a person in a swimming pool captured against the drain of the swimming pool.  
         [0018]     These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The present invention will be described with greater specificity and clarity with reference to the following drawings, in which:  
         [0020]      FIG. 1  illustrates a conventional prior art debris collection trap for use with a swimming pool;  
         [0021]      FIG. 2  illustrates a debris collection trap incorporating a hydraulic suction fuse and showing the normal mode of operation;  
         [0022]      FIG. 3A  illustrates a hydraulic suction fuse in a first state representative of normal operation;  
         [0023]      FIG. 3B  illustrates the hydraulic suction fuse in a second state resulting from clogging of a drain in a swimming pool;  
         [0024]      FIG. 4  illustrates a debris collection trap shown in  FIG. 2  but wherein the hydraulic suction fuse is in its second state;  
         [0025]      FIG. 5  illustrates a variant hydraulic suction fuse in its first state;  
         [0026]      FIGS. 6A, 6B ,  6 C and  6 D illustrate the change in configuration of the variant hydraulic suction fuse being transformed from the first state to a second state;  
         [0027]      FIG. 7  illustrates manual resetting of the variant hydraulic suction fuse; and  
         [0028]      FIG. 8  illustrates a hydraulic suction fuse in line with a swimming pool drain and a pump.  
     
    
     DESCRIPTION OF THE INVENTION  
       [0029]     Referring to  FIG. 1 , there is illustrated a debris collection trap  10  of the type described in U.S. Pat. No. 5,265,631 (hereinafter referred to as the &#39;631 patent). The trap is located adjacent the side of a swimming pool and recessed below the surface of pool deck  12 . Such location permits the trap to be made relatively large for significant capacity without being obtrusive to users of the swimming pool. The trap includes an elongated tank  14  having a bottom closure unit  16  and top inlet unit  18 . The closure unit may include a first outflow pipe  20  conveying water to a pump  22  and a filter  24  downstream thereof to filter the water received. The water is then returned to the pool, as indicated. Closure unit  16  may include a second pipe  26  conveying water to an auxiliary pump  28  that provides water to a cooling spray, waterfall, or other water emitting elements attendant the pool, as indicated. A closure  30 , such as a pivotal plate illustrated, may be incorporated to selectively limit water flow through pipe  26 . The upper extremity of tank  14  is mounted within an opening  32  in pool deck  12 . A removable plate  34  supported by the pool deck or by a fitting  36  mounted therein may be employed.  
         [0030]     Inlet unit  18  includes a hollow stub  40  for connection to pipe  42  in fluid communication with a drain, such as main drain  44  at the bottom of the swimming pool. A further stub  46  supports a pipe  48  for conveying water from a skimmer  50 . An inlet  60  to inlet unit  18  is connected to a balanced line (not shown) for conveying water by gravity from the swimming pool to replenish, as necessary, water  62  within tank  14  above inlet unit  18 . A conventional strainer  64  depends from inlet unit  18  and receives water from pipes  42  and  48 , along with any debris entrained therein or conveyed thereby, as depicted by arrows  66 ,  68 . The debris flowing into the strainer is retained therein and the water flows out through the strainer and into pipe  20  extending from closure unit  16 , as depicted by arrows  70 . A cover  72  is detachably attached to inlet unit  18  in sealing engagement therewith. The main purpose of cover  72  is that of providing access to strainer  64  and withdrawal thereof to permit removal of the debris collected therein by drawing the strainer upwardly after removal of plate  34 .  
         [0031]     In operation, upon actuation of pump  22 , water is drawn from within tank  14  and the suction developed within the tank will draw water through main drain  44  and pipe  42  into the tank. Similarly, water will be drawn from skimmer  50  through pipe  48  into the tank. The low pressure or suction within the tank will maintain cover  72  in essentially sealed engagement with inlet unit  18 . As inlet  60  is connected via a pipe to the water in the swimming pool, water level  74  of water  62  above cover  72  will be at the same elevation as the water level of the pool. Except for some seepage that may occur due to the below atmosphere pressure within tank  14  below inlet unit  18 , water  62  will not mix with the water in the tank below the inlet unit.  
         [0032]     Depending in part upon the power of pump  22 , the suction (low pressure) within tank  14  may be significant in order to draw water from main drain  44  through pipe  42  into tank  14 . This suction pressure (or low pressure) is essentially translated to the opening of the main drain. Should a body part of a person using the swimming pool inadvertently cover the main drain, the resulting suction force (vacuum) would tend to draw the person into contact with the main drain and hold the person there. Should the person be a child or a person of inadequate strength, the person may not be able to move away from the drain and may drown. Furthermore, the person may suffer injuries during efforts to extricate himself/herself away from the drain. If a skimmer  50  is also attached to tank  14  via a pipe  48 , the suction otherwise that would be present at the main drain will be somewhat relieved. However, if the skimmer is clogged or nearly clogged, relief of the suction force at the main drain is di minimus.  
         [0033]     To prevent the potentially disastrous results of a person becoming captured by the suction force at a main drain of a swimming pool, some mechanism must be employed to minimize or at least reduce the suction force responsible for capturing such person.  
         [0034]     Referring to  FIG. 2 , there is illustrated a debris collection trap  80  which may be the same as debris collection trap  10  shown in  FIG. 1  or a functional equivalent thereof. In view of the above discussion of debris collection trap  10  shown in  FIG. 1 , the description of debris collection trap  80  shown in  FIG. 2  will be essentially in summary form other than the improvement thereto constituting the present invention. Elements illustrated in  FIG. 2  common with elements shown in  FIG. 1  will be assigned common reference numerals for identification purposes.  
         [0035]     As with debris collection trap  10 , debris collection trap  80  is mounted below ground and usually beneath the surface of the deck surrounding a swimming pool, such as pool  82 . Inlet unit  18  includes a hollow stub  40  connected to pipe  42  drawing water from drain  44  at the bottom of pool  82 . The inflowing water, as a result of suction (low pressure) generated by pump  22  through pipe  20  extending from closure unit  16  enters strainer  64 , as depicted by arrow  84 . If a skimmer  50  is connected, water is drawn therefrom through pipe  48  into hollow stub  46  and vents into strainer  64 , as depicted by arrow  86 . A cover  88  is detachably attached to the top of inlet unit  18 . It may include a skirt  90  mating with the interior of cylinder  92  at the top of the inlet unit. A circumferential lip  94  rests upon the upper edge of the cylinder to limit movement of cover  88  with respect to the inlet unit. Water  62  above the inlet unit is in fluid communication with water  96  in pool  82  via a pipe or conduit  98  extending from the pool into the debris collection trap via hollow stub  100 . Hence, water level  74  at the top of debris collection trap  80  is at the same level as water level  102  in pool  82 . As depicted by arrows  104 , the water entering strainer  64  flows out of the strainer through the bottom of closure unit  16  into pipe  20 , as depicted by arrow  106 . The strainer collects the debris, such as leaves, etc., drawn from the pool through drain  44  into the debris collection trap. Upon upward movement of cover  88 , the strainer is exposed and it may be removed by lifting it and emptying it at a suitable debris disposal location.  
         [0036]     Referring jointly to  FIGS. 2, 3A ,  3 B and  4 , hydraulic suction fuse  110  will be described in detail. Cover  88  includes an opening  112  generally centrally located therein and including an inwardly radially extending lip  114  serving in the manner of a shoulder. A disc-like support  116  is disposed within opening  112  and supported by lip  114 . It includes a centrally located aperture  118 . A magnet, such as a ring magnet  120 , is formed in or attached to support  116  in a circumscribing relationship with aperture  118 . Support  116  supports a basket  122  extending downwardly therefrom and defined by a plurality of longerons  124  terminated by a base  126 , which base may be perforated. A float  128  is captured within basket  122  with the freedom to move vertically within the basket. The float includes a disc  130  of steel or other magnetically responsive material disposed in the upper part of the float. The disc may be fully enclosed, as illustrated, to prevent deterioration by the chemical action of chlorine present in the water of the swimming pool. Similarly, magnet  120  may be fully enclosed within support  116  for the same reason. It is to be understood that the locations of the magnet and the disc may be reversed. Water present within inlet unit  18  (see  FIG. 2 ), will cause float  128  to rise against support  116  and be retained thereagainst by the magnetic force exerted by magnet  120  upon disc  130 .  
         [0037]     When water inflow through pipe  42  (see  FIG. 2 ) into debris collection trap  80  is less than the outflow of water through pipe  20  due to an obstruction at drain  44 , water level  136  within the debris collection trap will drop below float  128  and the float will no longer be supported by the water. Additionally, the resulting suction (low pressure) within the debris collection trap relative to the pressure exerted by the head of water  62  above cover  88  will exert a downward force upon float  128 . When the combination of lack of water support for the float and the differential pressure acting on the float is sufficient to overcome the magnetic retaining force of magnet  120  acting on disc  130 , the float will tend to drop downwardly until it comes to rest against base  126 , as shown in  FIG. 4 . When this happens, the suction force that was present at drain  44  will cease to exist, as described below.  
         [0038]     As particularly shown in  FIG. 3B , when float  128  drops to the lower end of basket  122 , the water above cover  88  will flow downwardly through aperture  118 , as depicted by arrows  132  and into basket  122 . As the basket includes a plurality of slots defined by longerons  124  or is otherwise apertured, the water will flow out from basket  122 , as depicted by arrows  134  and flow into inlet unit  18 . The rate of flow of water through pipe  98  into the debris collection trap above cover  88  is less than the rate of water outflow from the debris collection trap into pipe  20 . Hence, aperture  118  will be exposed to the atmosphere. The resulting fluid communication between the interior of inlet unit  18  with the atmosphere (through aperture  118 ), will essentially eliminate any suction force (vacuum) at stub  40 . Such lack of suction force will be translated through pipe  42  to drain  44  resulting in a lack of suction force at the drain. Thus, the suction force tending to retain a body part of a person adjacent the drain will cease to exist and the person will be free to move away from the drain.  
         [0039]     Because water level  74  within the debris collection trap will drop and be below water level  102  in pool  82  (see  FIG. 2 ), water will continue to flow through pipe  98  to the top of the debris collection trap. This water flow, being urged by gravity, will be at a lesser rate than the water drawn out of the debris collection trap by pump  22 . When air is drawn from the debris collection tank through pipe  20  to pump  22 , the impeller associated with the pump will tend to cavitate. Such cavitation will cause the pump not to draw water from the debris collection tank through pipe  20 . When drain  44  is no longer obstructed, water will flow through the drain, into pipe  42  and into the debris collection trap as stub  40  is below water level  102  in the pool. The water flowing through aperture  118  of the hydraulic suction fuse into the debris collection trap in combination with the water flowing through stub  40  will fill the debris collection trap as the pump us cavitating and pumping very little water. As the debris collection tank fills float  128  will rise until, at the urging of the magnetic force of magnet  120 , closes aperture  118 . Thus, the hydraulic suction fuse is self resetting. Such closure will stop further air flow into the debris collection tank and ultimately to pump  22 . The downwardly flowing water (but no air) to pump  22  will cause the pump to become primed and begin to draw water from the debris collection tank. Simultaneously, the resulting suction (low pressure) within the debris collection tank will cause water to flow from drain  44  through pipe  42  and through stud  40  into the debris collection tank and normal operation will be resumed.  
         [0040]     A hydraulic suction fuse variant  140  is shown in  FIG. 5 . Cover  88  (see  FIGS. 2 and 4 ) includes a generally centrally located aperture  142 . A circular shroud  144 , including a radially inwardly extending flange  146 , extends upwardly about aperture  142 . Variant  140  includes a ring  148  having a stem  150  extending therefrom. A flexible disc  152  is mounted at the lower end of the stem. The disc is configured to be captured interiorly of shroud  144  and of greater diameter than the interior diameter of flange  146 . Moreover, the disc is of greater diameter than aperture  142 .  
         [0041]     Referring jointly to  FIGS. 6A, 6B ,  6 C and  6 D, the function of variant  140  will be described. When water within debris collection trap  80  is drawn out through pipe  20  by pump  22  upon covering or clogging of drain  44 , suction (vacuum) is developed within the debris collection trap and such suction is not relieved by an inflow of water through pipe  42 . The resulting increase in suction will create a pressure differential across disc  152  causing the disc to bend or bow downwardly as illustrated in  FIG. 6A . Such bowing will continue, as shown in  FIG. 6B  until the diameter of the disc approximates the diameter of aperture  142 . Thereafter, the disc will be drawn downwardly below cover  88 , as shown in  FIG. 6C . Further downward movement of variant  140  is prevented by ring  148  interferingly engaging the interior circular edge of flange  146 . However, cover  88  has now been opened, as shown in  FIG. 6D . Thereafter, water  62  (see  FIG. 2 ) above cover  88  will flow downwardly, as depicted by arrows  154  and through aperture  142 , as depicted by arrows  156 . The resulting water flow into debris collection trap  80  will maintain pump  22  primed but because debris collection trap  80  is no longer a closed vessel, insufficient suction will be developed therein to draw water through pipe  42 . The lack of water flowing into pipe  42  at drain  44  will relieve any suction present at the drain and should a person have been captured by such suction, the person is now free from restraint and can easily move away from the drain; it is to be understood that due to the difference in the water level and of the swimming pool and the water level in the debris collection trap, gravity will cause a water flow of a limited flow rate and the resulting suction at the drain is of little or no consequence.  
         [0042]     Variant  140  may be reset, as figuratively depicted in  FIG. 7 . That is, a person can engage ring  148  with his/her finger  158  and pull upwardly on variant  140 . Such upward pull will relocate disc  152  within the confines of shroud  144  and flange  146  above cover  88  defining aperture  142  and the seal of aperture  142  will be reset.  
         [0043]     Referring to  FIG. 8 , there is illustrated a suction fuse  110  or a variant suction fuse  140  at a location adjacent a swimming pool not incorporating a debris collection trap described above. That is, this figure illustrates the possibility of using one of the hydraulic suction fuses described above with any drain, whether at the bottom or in a sidewalk of an existing or to be built swimming pool, spa, or the like.  
         [0044]     For elements illustrated in  FIG. 8  common with those earlier described, common reference numerals will be used. A cylinder  160  depends from pool deck  12  into the ground. The depth of the cylinder must be sufficient to permit location of the hydraulic suction fuse below water level  102  in swimming pool  82 . A bracket  162  supports hydraulic suction fuse  110  in the manner of cover  88  or supports variant hydraulic suction fuse  140  in the manner of cover  88 , as shown in  FIG. 5  and  FIGS. 6A  to  6 D. Pipe  98  is in fluid communication with water  96  in swimming pool  82  and with the interior of cylinder  160  through stud  164 . Thereby, water level  74  within the cylinder is at the same elevation as water level  102  in the swimming pool. Pipe  42  coveys water from drain  44  to stud  166  in fluid communication with the interior of cylinder  160  below bracket  162  (compartment  174 ). Pipe  20  is in fluid communication with the interior of cylinder  160  below bracket  162  (compartment  174 ) through stud  168  to convey water to pump  22 . The outflow of the pump, represented by arrow  170 , is directed to the filtration system of the swimming pool, as is conventional. A conventional cover  172  is removably attached to the upper end of cylinder  160 . The cover may include an aperture or fit sufficiently loosely to prevent any pressure differential between the air space at the top of the cylinder and atmospheric pressure.  
         [0045]     In operation, in the event drain  44  becomes covered, hydraulic suction fuse  110  will be actuated and air will be caused to enter the cylinder below bracket  162  and be drawn into pump  22 , as described above. The resulting lack of suction force within compartment  174  below the bracket will be communicated to drain  44 . The resulting lack of suction force at drain  44  will permit easy removal of the material covering the drain or movement of a person away from the drain. Upon such removal of the flow impediment at the drain, compartment  174  will fill through pipe  98  and pipe  42  until hydraulic suction fuse  110  seals itself as a result of the rising water level within compartment  174 . Thereafter, flow through the pump from drain  44  will resume.  
         [0046]     In the event variant hydraulic suction fuse  140  is actuated, manual resetting of the fuse must be done. Such manual resetting may readily be accomplished by removing cover  172  and reaching into the cylinder to grasp ring  148  of variant hydraulic suction fuse  140  and drawing disc  152  into shroud  144 . Thereafter, fluid communication between drain  44  and pump  22  will exist and operation of the pump will resume.

Summary:
A hydraulic suction fuse is mounted in a conventional debris collection trap of a swimming pool, spa or the like, to significantly reduce or eliminate any suction force on the bottom or side wall mounted drain of the swimming pool, spa or the like, as a result of the drain becoming essentially wholly covered by a body part of a person or other drain clogging article. Alternatively, the hydraulic suction fuse may be mounted in a compartment in line between the drain and a suction pump of a swimming pool, spa or the like. Thereby, a person captured by the suction force at the drain will be released and the person is free to move away from the drain essentially instantaneously upon contact with the drain. In one embodiment, the hydraulic suction fuse is self resetting once inflow through the drain is no longer restricted. In another embodiment of the hydraulic suction fuse, the hydraulic suction fuse may be easily manually reset.