Patent Publication Number: US-6219856-B1

Title: Flow restrictor for water closet refill tube

Description:
This invention relates to water flow restrictors to reduce water wastage during bowl refill of water closets. 
     In conventional water closets comprising a bowl and a tank which receives flush water for selectively discharging to the bowl, the bowl is simultaneously refilled with water as the tank is refilled. Since the tank is much larger than the bowl and typically fills at a significantly slower rate, once the bowl fills, added refill water supplied thereto discharges into the water closet discharge plumbing, wasting the water thereafter supplied to the bowl as the tank continues to fill. Since in the United States, at least, the sole water supplies to a community is potable, treated, water, this waste of the excess water, while not considerable for each flush, when multiplied by millions of people, for up to 6-8 flushes per day, amounts to a considerable drain on increasingly precious potable water resources. Chemicals used to treat potable water supplies are discharged to the groundwater, further contaminating natural water supplies. This wastage of significant amounts of potable water thus is expensive both in terms of cost and of harm to the environment. 
     The prior art recognizes this problem, and several solutions have been offered heretofore. For example, U.S. Pat. No. 4,764,996 to Pino provides a pinch clamp for restricting flow through the bowl&#39;s flexible refill tube, and a threaded metal fitting is attached to the tube for securing an S-shaped wire to secure the refill tube end to the rim of an overflow pipe. However, pinch tubes may not accurately control the water flow rate. 
     U.S. Pat. No. 5,134,729 to Shaw uses a plurality of flow control inserts which are retained in the refill tube by frictional engagement in the refill tube. These may have the problem that water pressure in the tube may force the inserts out of the refill tube. 
     U.S. Pat. No. 5,058,216 to Trayer et al discloses a variable flow control restrictor, and U.S. Pat. No. 4,145,775 to Butler discloses a two piece hollow assembly whose pieces are rotatable relative to each other to vary the flow rate therethrough. Another adjustable valve device is disclosed in U.S. Pat. No. 4,980,932 to Stemples. However, adjustable devices are relatively costly and may be difficult for the average homeowner to install. Other water closets having adjustable water filling devices are illustrated in U.S. Pat. No. 5,259,074 to Battle, U.S. Pat. No. 4,538,307 to Barnum et al and U.S. Pat. No. 5,004,462 to Mahler. 
     There is still a need for a simple, low cost restrictor that can be readily installed by a layman and that reduces the amount of water wasted for each flush of a water closet. 
     SUMMARY OF THE INVENTION 
     A conventional water closet includes a toilet bowl, a toilet tank for supplying flush water to the bowl, water supply means for supplying water to fill the tank and bowl refill means including a thermoplastic, flexible tube having a first bore of a given internal diameter. The water supply means supplies fill water to the bowl simultaneously with fill water to the tank, but the bowl fills more rapidly than the tank, and overflows to a water closet discharge. The present improvement comprises, in accordance with one embodiment of the present invention, a restriction member having external threads along its outer periphery and having a second bore smaller than the first bore for insertion into the first bore, thereby restricting the bowl refill rate, and limiting the amount of excess water that overflows into the water closet discharge. The external threads have a tooth crest outer diameter greater than the first bore internal diameter, thereby providing threaded interference engagement between the restriction member having external threads and the refill tube first bore. 
     In accordance with a further embodiment of the present invention, tool receiving means are formed in the tubular restriction member at one end to permit attachment of the external threaded restriction member to the thermoplastic refill tube at a tube end. In a further embodiment, the tool receiving means is a slot for a screw driver tool. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a fragmented side elevational view partially in section, of a water closet according to one embodiment of the present invention. 
     FIG. 2 is an isometric view of a refill tube flow restriction member having external threads used in the embodiment of FIG.  1 . 
     FIG. 3 is an elevational sectional fragmented view of the restriction member of FIG. 2 about to be inserted into the bowl refill tube, showing the relation of the various bore diameters. 
     FIG. 4 is a sectional partial elevational view of the e nd of the bowl refill tube with the restriction member of the present invention inserted therein. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, a water closet  10  has a flush water receiving tank  11 , the closet being conventional and as described in the aforementioned U.S. Pat. No. 4,764,996 and 4,145,775, incorporated herein by reference. The tank  11  has a water inlet  12  and a water outlet  14 . A conduit  16  is connected to a source (not shown) of pressurized water at inlet  12 . A discharge pipe  18  is connected at its upper end to outlet  14  and at its bottom end to a conventional bowl  20  having a seat  22  and a cover  24 . 
     An intake valve  25  is mounted on the top of the intake conduit  16 , and includes a valve casing  26  with a vertical bore  28  and a valve seat  30  at the bore bottom. A valve stem  31  has a ball valve  32  connected thereto seated against the seat  30 . The stem  31  has an end opposite to the valve  30  connected to a sliding piston  33  in the bore  28 . 
     The valve casing  26  has an arm  34  extending into the tank  11  and has a downwardly extending opening water outlet  35  connected to the bore  28  by a bypass  37  and closet tank filling tube  36 . A lever  38  is pivoted to the pin  39 , the other end of the lever having a socket  42 . A float rod  44  end is secured to the socket  42 . A ball float  58  is connected to the rod  44  at its other end. A link  48  is pivoted at pivot  46  to the lever  38  at one link end, and at the other link end to a lever  52  at the pivot  50 . The lever  52  is pivoted midway between its ends to the arm  34  and at its other end to the piston  33  to open the intake valve  25  in one direction, and close it in the other direction. The piston  33  controls the flow of water through the intake valve  25 . A refill tube  56  is coupled to the top of the water outlet  35  at one end to an already installed fitting, and the other end of the refill tube  56  extends into the overflow pipe  88 . The refill tube  56 , already an existing part of the water closet mechanism, is made suitably of a thermoplastic which is pliable and flexible. The refill tube  56  has a threaded fitting at one end for attachment to the outlet  35 . 
     In the prior art, the discharge end of the refill tube  56  normally is suspended in the upper end of the overflow pipe  88  by an S-shaped hook. In such water closets requiring an S-shaped hook to retain the refill tube  56  in the overflow pipe  88 , it would still be required in the present invention, as further explained hereinbelow, so that the refill tube  56  is not displaced from the overflow pipe. When the S-shaped hook is suspended in the refill tube  56 , it is placed such that only a small portion of the refill tube extends into the overflow pipe  88 . The refill tube  56  fills the bowl  20  simultaneously when the tank  11  is filled via fill pipe  36 . As the tank  11  fills, water flows through the refill tube  56  into the overflow pipe  88  into the bowl  20 , filling the bowl  20 . Unless otherwise provided for, the bowl  20  fills much quicker in most water closets than the tank  11 . 
     A water flow restriction member  200 , in accordance with the present invention, is inserted into the end of the refill tube  56  which extends inside the overflow pipe  88 . The restriction member  200  restricts the flow of water to the bowl  20  so that the bowl  20  fills more slowly in order to match the filling rate of the tank  11 . In FIG. 2, the restriction member  200  has a circular cylindrical body  201  which is preferably made of a rigid thermoplastic, e.g., nylon, and has external threads  202 . The body  201  has an axially extending central circular cylindrical bore  204  in communication with both ends of the body  201 . A screw driver receiving slot  206  is formed in one end of the body  201 . 
     When an S-shaped hook is employed, referred to hereinabove, the restrictor  200  is screwed into the refill tube far enough, approximately ¾ of an inch, to permit the S-shaped hook to be inserted in the end of the refill tube  56 . 
     In water closets having a retaining device already installed in the top of the overflow pipe  88 , the restrictor  200  is screwed into the end of the refill tube  56 , when the refill tube  56  is reinserted into the installed retainer. 
     In FIG. 3, the refill tube  56  has a bore  208 . This bore  208  has a diameter d. The external threads  202  of the restriction member  200  have a thread crest outer diameter d 1 . The diameter d 1  is greater than diameter d. This results in an interference fit of the threads  202  in the bore  208  of the refill tube  56  wherein the threads bite into the yielding soft plastic material of the refill tube  56  as the restriction member  200  is inserted, as by a twisting motion. The bore  204  has a diameter d 2  sized such that water flowing through the bore  204  will just fill the bowl  20  when the tank  11  is also just filled during the refill cycle. 
     To insert the restriction member  200  into the refill tube  56 , a tool, such as a screw driver (not shown) may be utilized to drive the restriction member  200  into the bore  208  of the refill tube  56 . Because of the interference fit, the refill tube  56  outer diameter may bulge somewhat at region  210 , see FIG.  4 . This interference fit provides a relatively high engagement friction load between the restriction member  200  and the refill tube  56 . The plastic of the refill tube  56 , being relatively soft, deforms so that its material conforms somewhat to the shape of the threads  202 , as shown in FIG.  4 . The plastic material of the refill tube  56  inner wall need not identically conform to the exact shape of the threads  202 , as long as the restriction member  200  is forcibly retained within the refill tube  56  bore  208 . Also, water pressure in the refill tube  56  can not disengage restriction member  200  because of the threaded engagement and because of the frictional forces as well. 
     The screw driver slot  206  is not critical, as other means may be employed to insert the restriction member  200  into the refill tube  56 . Such means can include a temporary nut attached to the restriction member  200 . This nut can later be removed from the restriction member  200  if desired. However, the screw driver slot  206  is preferred because of the simplicity of insertion of the restriction member  200  into the bore  208 , and the ease of removal of the restriction member  200  from the refill tube  56  if required. Also, high turning insertion forces can be provided to the restriction member  200  by using a tool such as a screw driver. The insertion forces can be set by setting the desired thread diameter of the restriction member  200  by using different diameter threads  202 . The amount of interference plainly will set the insertion load. This interference load also depends upon the type of plastic material used for the refill tube  56 , which is supplied with the water closet  10 . 
     Preferably, the bore  204  of restrictive member  200  has a diameter such that the bowl can fill without excessive overflow, and can vary somewhat, suitably in the range of about {fraction (1/16 )}to about {fraction (5/32 )}inch for most water closets. This range may differ in accordance with a particular water closet tank fill rate and water pressure. For conventional water closets, the restriction member  200  internal bore diameter may be at least {fraction (5/64 )}inch, and preferably is about {fraction (3/32 )}inch, to maintain a proper flush for the bowl  20 . Newer water closets of reduced capacity, e.g., 1.6 gallon of water capacity, will require a restriction member  200  diameter of about {fraction (9/64 )}inch. 
     The restriction member  200  preferably is formed from conventional threaded nylon screw stock of ¼ 20 threads and has an axial length of about ½ inch. Because refill tubes  56  of newer 1.6 gallon water closets are smaller than older models, the restriction member  200  may be formed of {fraction (12/24 )}screw stock. These examples are illustrative only, and the outer diameter of the restriction member  200  is not critical, except that it must be larger than the bore  208  of the refill tube  56 . 
     While a screw driver is described as suitable for driving the restriction member  200  into the bore  208  of the refill tube  56 , other embodiments may be used, e.g., the restriction member  200  may be formed with flattened sides to receive a wrench for insertion of the restriction member  200  into the refill tube  56 . The restriction member  200  is preferably made of thermoplastic, but may also be made of metal if desired. However, thermoplastic is less expensive and is not subject to corrosion, and thus is preferred. 
     The remaining structure of the water closet  10  of FIG. 1 is conventional. As a result of the present invention, a simple, low cost, reliable water flow restriction member is provided which is simple to install and that is adaptable to different size bowl refill tubes  56 . 
     Various modifications may be made to the above-described embodiments of the restriction member, as will be known to one skilled in the art. The embodiments shown and described hereinabove are illustrative only and are not meant to limit the scope of the invention, which is meant to be limited only by the appended claims.