Patent Publication Number: US-2022213709-A1

Title: Pool filtration system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefits of priority to U.S. Provisional Patent Application No. 63/134,453, filed Jan. 6, 2021, titled POOL FILTRATION SYSTEM, the contents of which are hereby expressly incorporated into the present application by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a pool filtration system that comprises a backwash filter. The backwash filter allows for reintroduction of filtered backwash water into the pool. 
     BACKGROUND OF THE INVENTION 
     Swimming pool filtration systems typically include a drain discharge connected to the intake of a pump by a suction line to withdraw water from the pool. The suction line usually includes a skimmer for removing large debris before the water flows to a main filter that filters dirt, sediment, and other contaminants from the water. In a large proportion of residential swimming pools, this main filter is a sand filter. The filtered water is then returned back to the pool. 
     Over time, the collected dirt and debris in the filter slows down the water flow and generally decreases the overall efficiency of the unit. Pressure gauges at the filter inlet and outlet give the pool owner an idea of the blockage level inside. If gauges show pressure that exceeds a certain level, then it is time to clean the filter through a backwash operation. To backwash, typically a valve at the filter is actuated to connect the pipe from the pump to the outlet pipe and connect the drainage pipe to the inlet pipe. With this arrangement, water from the pump pushes up through the sand, dislodging the dirt and debris. At the top of the filter tank, the backwash water, containing much of the dirt and debris, flows out through the drainage pipe. 
     After the backwashing is finished, this contaminated water is typically disposed of in a variety of ways, such as into a storm drain, a sewer, a local creek etc. None of those are preferred options, and may actually be illegal in certain areas. The backwashed water is typically chemically treated, and can damage plant life, aquatic life, and groundwater. Backwashing is typically a necessary step for most pool filter systems, but it is an undesirable one, not only because of the environmental concerns. For example, backwashed water needs to be replaced with new water for the pool, which adds expense. Typically, and especially in northern climates, pool water is heated, so warm backwashed water is replaced with cold new water, which needs to be heated again, also adding expense. 
     U.S. Pat. No. 5,505,844 discloses a swimming pool filtration system comprising a pump, sand filter, and a backwash filtering system. U.S. Pat. No. 3,365,064 discloses a swimming pool filtration system comprising a pump, a main filter, a backwash filter, and multiple valve assemblies. When a valve stem is in a certain position, such as during a backwash procedure, valve elements occlude certain valve openings that block off the pump discharge line to the pool. The backwash carrying sediment is then diverted to the backwash filter  13 . U.S. Pat. No. 4,545,905 discloses a filter backwash system in combination with a swimming pool. The system comprises a pump, filter canister, and backwash filter. When the filter medium needs cleaning, the system is backwashed, after which backwashed water exits the filter canister and enters the backwash filter. These three references are incorporated herein by reference. 
     A need exists for an efficient pool filtration system that filters backwash water for reintroduction back into the pool. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention is provided a pool filtration system for a pool, comprising: an intake conduit in fluid connection with said pool, for drawing water from the pool; a return conduit in fluid connection with said pool and with said intake conduit, for returning water to the pool; a circulation pump for circulating water within the system; a valve with at least a first, operating position and a second, backwash position; a primary filter; a backwash filter; and a backwash return conduit; wherein, when the valve is in the operating position, water is directed from the intake conduit to the primary filter in a filtering direction, then to the return conduit and back to the pool; and wherein, when the valve is in the backwash position, water is directed from the intake conduit to the primary filter in a backwash direction which is opposite to the filtering direction, then to a backwash conduit to the backwash filter, then through the backwash return conduit and back to the pool. 
     According to a further aspect of the invention is provided a backwash filter for the pool filtration system as herein described, wherein the backwash filter comprises: a substantially tubular housing having a sealed lower portion, a middle portion, and an upper portion, having an inlet which directs incoming water towards the lower portion, and having a removable cap on its upper portion; a water filter retainer within said housing and in its middle portion, configured to retain a water filter to form a water tight seal between the lower portion and the upper portion such that, when a water filter is retained within the water filter retainer, water travelling from said lower portion to said upper portion must travel through the water filter; said cap having an outlet for directing water out of the upper portion. 
     In certain embodiments, said inlet is angled to direct water towards the bottom of the lower portion. 
     In certain embodiments, the water filter is spring mounted onto the water filter retainer. 
     In certain embodiments, the water filter is disposable. 
     In certain embodiments, the water filter is a paper cartridge filter. 
     In certain embodiments, the water filter is a cloth filter. 
     In certain embodiments, the water filter is reusable and cleanable. 
     In certain embodiments, the pool filtration system further comprises a water heater inline with said return conduit. 
     In certain embodiments, the pool filtration system further comprises an ozonator inline with said return conduit. 
     In certain embodiments, the pool filtration system further comprises a chlorinator inline with said return conduit. 
     In certain embodiments, the pool filtration system further comprises a salt ionizer inline with said return conduit. 
     In certain embodiments, the valve is configured to be operated manually. 
     In certain embodiments, the valve is configured with a motor so that it may be switched from the first position to the second position with a switch. 
     In certain embodiments, the valve is configured with a motor, and the return conduit is configured with a pressure sensor, so that when a low pressure threshold is met, the valve automatically switches from the first position to the second position, then automatically switches back to the first position after a defined period of time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described in more detail having regard to the drawings in which: 
         FIG. 1  is a pictorial diagram illustrating an embodiment of the pool filtration system; 
         FIG. 2  is a cross-sectional view of a backwash filtration unit according to an embodiment of the present invention; 
         FIG. 3  is an exploded view of the backwash filtration unit as shown in  FIG. 2 ; and 
         FIG. 4  is a block diagram illustrating a method for pool filtration according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A better understanding of the present invention and its objects and advantages will become apparent to those skilled in this art from the following detailed description, wherein there is described only the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of modifications in various obvious respects, all without departing from the scope and spirit of the invention. Accordingly, the description should be regarded as illustrative in nature and not as restrictive. 
       FIG. 1  shows an exemplary embodiment of a pool filtration system  10 . In this system  10 , a pool  12 , such as an in-ground swimming pool  12 , will have a pump  14  actuated by a motor  16  that creates negative pressure to pull water from the pool  12 . Depending upon the size of the pool  12 , the water can be extracted from the pool  12  via one or more drains  18 . One or more drains (not shown) located near the surface of the pool  12  will preferably direct the drained water into a skimmer  20 . Skimmers  20  help to capture large debris, such as leaves, twigs, dead insects, etc., before this waste can sink to the bottom of the pool, or before the debris makes its way to the pool filter  24 . Once through the skimmer  20 , the water is directed to the pool filter  24  via a conduit  22 . Alternatively or in parallel, as shown in  FIG. 1 , water may exit the pool  12  via a drain  18 , such as a drain at or near the bottom of the pool  12 , which can either bypass skimmer  18  or be routed through skimmer  18  and directed through a conduit  22  straight to the pool filter  24 . 
     Pump  14  may optionally also have a basket-type filter (not shown) for filtering larger particulate matter missed by the skimmer basket. 
     The system may have additional elements, not shown in  FIG. 1  but which are common to pool systems. These additional elements may include, for example, a chlorinator, typically located downstream of the filter, for introducing chlorine into the water, or, typically alternatively to the chlorinator, but in some instances in addition to the chlorinator, a salt ionizing system for ionizing salt contained within the water (in the case of a salt water pool). Additional elements may also include a water heater or heat exchange system, for adjusting the temperature of the water, and a variety of sensors including a thermostatic sensor, an ion content sensor, an ozonator, etc. 
     During a normal filtering operation of the system  10 , a valve  26  directs the drained water into the pool filter  24  via an inlet, which is typically located near the top of the filter  24 . The pool filter  24  can be any type of filter, such as a sand filter, or a diatomaceous earth filter. The filter is designed to filter particulate matter smaller than what may have been captured in the skimmer bucket or pump basket filters. After the water passes through the filter  24 , it exits the filter through an outlet. The valve  26  directs the filtered water to a return conduit  32 , through which it is pumped back to the pool  12  through a return opening  38 . 
     When necessary, the valve  26  can be adjusted to place the system  10  in a backwash operation. In this operation, the valve  26  will now direct water drained from the pool  12  through the filter  24  in a direction reverse to what occurs during the normal filter operation. During the backwash operation, the water enters the filter  24  through the outlet, disrupts the filtration media in the filter  24  to dislodge debris and sediment caught in the filter  24 , and ultimately carries much of this debris and sediment as it exits the filter  24  through the inlet where it arrives back at the valve  26 . 
     The water exiting the filter  24  during the backwash operation will typically contain at least some amount of debris or contaminant that has been removed from the filtration media in the filter  24 . While prior art systems typically disposed of this water in e.g. storm drains, sewers, etc., when the valve  26  is adjusted to place the system  10  in a backwash operation, access to the return conduit  32  is blocked. Rather, the valve  26  directs the backwash water leaving the filter  24  through a backwash conduit  40  to a backwash filtration unit  42  where it enters via an inlet  48  for further processing. A backwash conduit valve may be connected to the backwash conduit  40  to further control the flow of the backwash water. 
     An embodiment of the backwash filtration unit  42 , as seen in  FIGS. 2 and 3 , comprises a housing  46  that is illustrated as being substantially tubular, with the exception of an inlet  48 . The inlet is preferably angled as shown in  FIGS. 2 and 3 , as this will direct the incoming backwash water toward a lower portion of the filtration unit  42 . A housing cap  50  is removably attached to a first end  52  of the housing  46 , such as through a threaded connection  54  as illustrated in the Figures. Alternatively, the housing cap  50  could be attached to the housing  46  through e.g. a press fit, a snap fit, or via a fastener, such as a screw or a latch. The removable nature of the housing cap  50  facilitates access to the inside of the housing  46 , which facilitates the cleaning or changing of the filter  60 . The opposing second end  56  of the housing  46  is enclosed with a top cap  58 . The top cap  58  is shown as attaching to the housing  46  through a snug press fit, however, other means known to one of skill in the art can be used to attach the second cap  58  to the housing  46 . 
     Inside the housing  46  is a cartridge filter  60 . The size of the housing  46  of the backwash filtration unit  42 , and thereby the size of the cartridge filter  60 , can vary depending upon the size of the pool  12  and volume of water to be filtered. A filter  60  having a larger surface area is desirable, as it should decreases clogging thereof, which will increase the time required between cleaning or replacement thereof. The filter may be a cartridge filter. It may be, for example, a paper cartridge filter, or it may be a cloth filter. It may be reusable, and washable by removing the filter and washing it down with a hose, or it may be disposable. Other types of filters are also contemplated for use within the backwash filter  42 . 
     A retainer  62  receives a first end  64  of the filter  60 , such as through slots  66  in the retainer  62 . The retainer  62  has a diameter slightly less than the inner diameter of the housing  46 , and serves to retain the filter  60  in place within the housing  46  through a press fit. To further secure the retainer  62  in place within the housing  46 , one or more seals  68  can be placed around the exterior edge  70  of the retainer  62 . For example, as can be seen in  FIG. 3 , the exterior edge  70  of the retainer  62  has at last one annular depression  72  configured to receive the one or more seals  68 . Not only will the seals  68  reinforce the positioning of the retainer  62  inside the housing, they will create a substantially water tight seal between a lower portion of the interior of the housing  46 , and an upper portion of the housing  46  above the retainer  62 . The opposing second end  74  of the filter  60  is secured against the interior face  76  of the housing cap  50 , and the open second end  74  of the filter is capped with a pilot filter  78 . 
     The retainer  62  also serves to cap the open first end  64  of the filter  60 . Within the retainer  62 , there is a retainer channel  76  that extends across the length of the retainer  62 . A tube  82  connects the retainer channel  76  with an exit channel  84  that extends across the length of the top cap  58 . The tube  82  can attach to the retainer channel  76  and the exit channel  84  through any known means, such as a threaded connection or a press fit means. The retainer channel  76 —tube  82 —exit channel  84  pathway provides for fluid communication between an interior  80  of the filter  60  and the exterior of the backwash filtration unit  42 . The cross section of the exit channel  84  may be linear throughout, or may flare outward, or have a cone or pyramid shape, to provide a broader opening at the exterior of the backwash filtration unit  42 , which may be necessary to couple with exterior conduits. 
     In one embodiment as shown in the Figures, a gate valve assembly  102  is attached to the cap  58 . The gate valve assembly  102  has an interior channel  104  contained therein, that when attached to the cap  58 , fluidly connects the exit channel  84  with an outlet  106 . The gate valve assembly can contain a known gate valve  108  to restrict or release the flow of water from the backwash filter  42 . 
     In one embodiment, additional means are utilized to secure the retainer  62  in place. As can be seen in  FIG. 3 , the slots  66  are not uniform across their length. A first end  86  of a slot  66  has a larger diameter than the opposing second end  88  of the slot  66 . Such an arrangement creates an edge  90  that is able to receive a head portion of a fastening member  92 , such as a bolt. The fastening member  92  extends through the first end  86  of the slot  66  until its head portion is retained by the edge  90 . The body of the fastening member  92  extends through second end  88  of the slot  66 , and is ultimately received by an aperture  94  on the interior face  96  of the top cap  58 . Preferably, a biasing member  98 , such as a spring, is placed over the body of the fastening member  92 . The biasing member  98  extends between an interior face of the top cap  58  and the retainer  62 , and places pressure on the retainer  62 , forcing it toward the filter  60 . This serves to further keep the retainer  62  in place within the housing  46 , and places additional pressure to secure the filter  60  in place between the retainer and the housing cap  50 . 
     As the backwash water enters the backwash filtration unit  42  through the inlet  48 , it will be filtered to remove debris as it passes through the filter  60 . Once it reaches the interior  80  of the filter, pressure from incoming backwash water will propel the filtered water up through the retainer channel  76 —tube  82 —exit channel  84  pathway, and if applicable, the outlet  106 , at which point the filtered backwash water will exit the backwash filtration unit  48 . 
     A backwash return conduit  100  is fluidly attached to the exterior opening of the exit channel  84  or outlet  106 , and directs the now filtered backwash water to the return conduit  32  to be returned to the pool via one or more return openings  38 . Flow of water in the backwash return conduit  100  can optionally be further controlled by a return valve (not shown). 
       FIG. 4  illustrates a block diagram of an embodiment of filtering water from a pool  12 . Step  200  includes pumping water from the pool  12  via a pool pump  14 . Step  210  includes optionally subjecting the pumped water to skimming via a skimmer  20  to remove large debris. 
     During a normal filtration operation (left side of the flow chart), a valve  26  will be actuated accordingly, which will direct the pumped water into a filter  24  via an inlet (Step  220 ). Step  230  includes filtering the water in the filter  24 . After filtration, the water is directed through an outlet of the filter  24  (Step  240 ). The valve  26  directs the filtered water through a return conduit back to the pool (Step  250 ). 
     Alternatively, during a backwash filtration operation (right side of the flow chart), the valve  26  will be actuated accordingly. Step  260  includes reversing flow of the pumped water, and directing the water through into the filter  24  through the outlet. Step  270  includes disrupting the filtration media. Step  280  includes carrying debris and sediment out of the filter  24  through the inlet. The valve has blocked the return conduit  32 , which results in Step  290  of directing the backwash water to a backwash filtration unit  42 . Step  300  includes filtering the backwash water through the backwash filtration unit  42 . The final step  310  includes returning the filtered backwash water to the pool  12  through an auxiliary return conduit  100 . 
     The valve  26  may be actuated to switch from normal position to backwash filtration (i.e. the left side to the right side), and back, in a manual operation, such as by a user turning a switch on the valve cover. Alternatively, the valve may be operated electrically, for instance, with a small servo motor, which may be attached to an electric switch for user control, or to a controller which automatically switches from one position to another based, for example, on a pressure reading of the return conduit meeting a low threshold, or based on a period of time. This may be either factory set or user programmable. For example, a user may program the controller to switch to a backwash operation once a week, for 30 minutes. Other possible configurations would be evident to a person of skill in the art.