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FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to fluid dispensing devices and, more specifically, to cleaning chemical dispensers for flush toilets.  
       BACKGROUND OF THE INVENTION  
       [0002]     Many devices have been proposed and manufactured for automatic dispensing of cleaning chemicals into flush toilets. Typical examples from recent prior art are U.S. Pat. No. 5,252,957 to Campau, U.S. Pat. No. 5,488,742 to Liao, and U.S. Pat. No. 6,151,722 to Lubrano. While the inventions therein disclosed apparently meet their stated objectives, none of the examples of the prior art have the combined advantages of simplicity and ease of manufacture, easy installation, and dosage control with resulting economy in chemical usage.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention seeks to provide a chemical dispenser for a flush toilet that is simple and inexpensive to manufacture, easy to install in existing toilets, and that provides a controlled dosage of chemical each time the toilet is flushed.  
         [0004]     There is thus provided, in accordance with a preferred embodiment of the invention, a chemical dispenser for use with a flush toilet including: 
        a chemical storage chamber for a chemical which is to be added to the flushing water of the toilet;     mounting apparatus fabricated to allow the chemical dispenser to be readily mountable on an existing opening in the water storage tank of the toilet; and     a dispensing mechanism operative to dispense a predetermined quantity of the chemical into the flushing water of the toilet each time the toilet is flushed. 
 
 Further in accordance with a preferred embodiment of the invention, the dispensing mechanism includes a float located in the water storage tank of the toilet operative to drive the dispensing mechanism as it rises and falls with the water level in the water storage tank of the toilet. 
       
 
         [0008]     In accordance with a further preferred embodiment of the invention, the dispensing mechanism is driven by the pressure of water flowing into the water storage tank of the toilet.  
         [0009]     In accordance with an additional preferred embodiment of the invention, the dispensing mechanism includes apparatus for producing an increase in pressure within the dispensing mechanism in response to the refilling of the water storage tank of the toilet after flushing, and for dispensing a predetermined quantity of the chemical into the flushing water of the toilet each time the toilet is flushed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings, in which:  
         [0011]      FIG. 1  is a representation of a chemical dispenser for a flush toilet, constructed and operative in accordance with a preferred embodiment of the present invention;  
         [0012]      FIGS. 2A and 2B  are representations, in two operative states: a filling state and a dispensing state, respectively; of a dispensing mechanism of a chemical dispenser for a flush toilet, constructed and operative in accordance with an alternative preferred embodiment of the present invention;  
         [0013]      FIG. 3  is a representation of a chemical dispenser for a flush toilet constructed and operative in accordance with a further embodiment of the present invention;  
         [0014]      FIG. 4  is a representation of a chemical dispenser for a flush toilet constructed and operative in accordance with a further preferred embodiment of the present invention; and  
         [0015]      FIG. 5  is shown a representation of a chemical dispenser for a flush toilet constructed and operative in accordance with an additional preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Referring now to  FIG. 1 , there is shown a representation of a chemical dispenser for a flush toilet, referred to generally as  100 , constructed and operative in accordance with a preferred embodiment of the present invention. Chemical dispenser  100  includes chemical storage chamber  101 , which has a removable stopper  103  to allow chamber  101  to be filled with the chemical to be dispensed. Chemical storage chamber  101  is mounted on toilet tank  120  via supply tube  109 , connecting sleeve  104 , and mounting ring  106 . Threaded ring  107  advantageously provides pressure on mounting ring  106  against connecting sleeve  104  and gasket  105  to fix chemical dispenser  100  in place with a fluid-tight seal. Note the angle of supply tube  109 , which allows the chemical in storage chamber  101  to flow into the device due to gravity. It should be further noted that since most toilet tanks are produced with two holes to provide alternative positioning of the water input valve, chemical dispenser  100  can be readily installed on most toilet tanks without the need to drill a new hole therein.  
         [0017]     Supply tube  109  feeds dispensing mechanism, referred to generally as  150 , via entry hole  123 . Dispensing mechanism  150 , in the present embodiment, is located within toilet tank  120 . When toilet tank  120  is full, as shown in the drawing, float  118  and attached rod  115  drive valve seat  114  upward in cylinder  127  so that entry hole  123  is uncovered, allowing the chemical to flow from storage chamber  101  via supply tube  109  and entry hole  123  into cylinder  127 , filling it and upper chamber  129 . Venting valve  111  releases the air pressure in upper chamber  129  so that it can fill with the chemical until float portion  131  of venting valve  111  rises to seal with upper stopper  110  of cylinder  127 , which further serves to prevent leakage of the chemical via venting valve  111 . Ring  112  on the upper portion of venting valve  111  prevents the valve from falling into upper chamber  127 , without sealing the venting air flow. This arrangement ensures that a predetermined amount or dosage of the chemical will be held in cylinder  127  and upper chamber  129  for dispensing into the water in toilet tank  120 .  
         [0018]     When the toilet is flushed, the water level in toilet tank  120  is below dispensing mechanism  150 , so that float  118  and attached rod  115  are driven downward by gravity and by spring  113 . Valve seat  114  is also lowered by gravity and by spring  113 , covering entry hole  123  and uncovering exit hole  125  to release the chemical into toilet tank  120 . As toilet tank  120  refills, float  118  and attached rod  115  will again rise, driving valve seat  114  upward to seal exit hole  125  and to uncover entry hole  123  as described above, thereby preparing another measured dose of the chemical for release the next time the toilet is flushed.  
         [0019]     Referring now to  FIGS. 2A and 2B , there are shown representations in two operative states: a filling state and a dispensing state, respectively, of a dispensing mechanism  250  of a chemical dispenser for a flush toilet, constructed and operative in accordance with an alternative preferred embodiment of the present invention. In the present embodiment, dispensing mechanism  250  takes the place of dispensing mechanism  150  of the embodiment shown in  FIG. 1 , with a similar chemical storage chamber, mounting, and supply tube  209 .  
         [0020]     When the toilet tank is empty, dispensing mechanism  250  is in its filling state as shown in  FIG. 2A . Float  218  lowers, as shown in  FIG. 2A , together with attached rod  215  and upper and lower portions of piston  231 ,  214 , respectively; which are further forced downward by lower spring  216  so that lower portion  214  of the piston uncovers entry hole  223  thereby allowing the chemical to enter the central chamber of dispensing mechanism  250  via supply tube  209  due to the force of gravity. Upper spring  213  maintains a constant spacing between upper  231  and lower  214  portions of the piston, thereby fixing the volume available in dispensing mechanism  250  for holding the chemical and hence, the dosage thereof. At the same time, upper portion  231  of the piston covers exit hole  225 , thereby preventing the chemical from leaving dispensing mechanism  250  and ensuring a constant dosage of the chemical will be ready for dispensing.  
         [0021]     When the toilet tank fills, dispensing mechanism  250  is driven by float  218  into its dispensing state, as shown in  FIG. 2B . Float  218  and attached rod  215  drive the piston upward so that its lower portion  214  covers entry hole  223 , preventing further entry of the chemical into the chamber, and so that its upper portion uncovers exit hole  225 , releasing the measured dose of the chemical into the toilet tank thereby.  
         [0022]     Referring now to  FIG. 3 , there is shown a representation of a chemical dispenser for a flush toilet, referred to generally as  300 , constructed and operative in accordance with a further embodiment of the present invention. Chemical dispenser  300  includes chemical storage chamber  301 , which has a removable stopper  303  to allow chamber  301  to be filled with the chemical to be dispensed. Chemical dispenser  300  is connected directly to dispensing mechanism, referred to generally as  350 , by which it is mounted on toilet tank  320 , via an existing hole therein, similar to the mounting of chemical dispenser  100  explained above in relationship to  FIG. 1 .  
         [0023]     When toilet tank  320  is full, float  318  rises, driving attached rod  315  upwards through dispensing mechanism  350 . Rod  315  has a sloped indentation or slot  331  in which rides eccentric protrusion  335  of valve seat  314 . When rod  315  is in its uppermost position, as shown in  FIG. 3 , eccentric protrusion  335  of valve seat  314  is driven all the way into sloped slot  331  by spring  313  to its leftmost position as shown in the drawing. In that position, the other end  337  (rightmost in the drawing) of valve seat  314 , which is slotted, thinned, or tapered, is positioned in the end cap  316  of dispensing mechanism  350 , thereby allowing the chemical in storage chamber  301  to flow, driven by gravity, into cylinder  327  of dispensing mechanism  350  via the slots in end portion  337 , thus filling it. At the same time, wide end  339  of valve seat  314  (leftmost in the drawing) will sit in the end of cylinder  327 , thus preventing exit of the chemical. Cylinder  327  preferably has a venting tube  341  aligned with slot  345  in wide end  339  of valve seat  314  to allow cylinder  327  to fill without resistance due to air pressure. Dosage of the chemical is determined by the internal volume of cylinder  327 .  
         [0024]     When the toilet is flushed, the water level in toilet tank  320  drops, as will float  318  with rod  315 , which are further driven downward by spring  311 . Eccentric protrusion  335  of valve seat  314  is driven by sloped slot  331  to its rightmost position as shown in the drawing, simultaneously sealing end cap  316  of dispensing mechanism  350  with the cylindrical portion of valve seat  314 , thereby preventing further flow of the chemical into cylinder; and offsetting wide end  339  of valve seat  314  from the end of cylinder  327 , thereby allowing the chemical to exit dispensing mechanism  350  for toilet tank  320  via slot  345  in valve seat  314  and exit hole  325 .  
         [0025]     Referring now to  FIG. 4 , there is shown a representation of a chemical dispenser for a flush toilet, referred to generally as  400 , constructed and operative in accordance with a further preferred embodiment of the present invention. Chemical dispenser  400  is contained within chemical storage chamber  401  and is typically mounted on toilet tank  420  on an existing hole therein, as explained above with respect to the embodiment shown in  FIG. 1 .  
         [0026]     When the toilet is flushed and water starts flowing into toilet tank  420  to refill it, the water passes, driven by the local water pressure, through chemical dispenser  400  via water inlet tube  421  from the toilet tank fill valve (not shown) which is attached to inlet sleeve  422  of chemical dispenser  400 . The fluid flows through lower conduit  425  into the dispensing mechanism, referred to generally as  450 , and impels driving sleeve  435  to the left, as shown in the drawing, until it catches valve seal cylinder  414  by shoulder ring  437  and drives it to the end of mixing chamber  429 . When valve seal cylinder  414  reaches the end of mixing chamber  429 , entry holes  423  from chemical storage chamber  401  are uncovered, allowing the chemical to enter mixing chamber  429  and mix with the flowing water that flows through slots  424  in valve seal cylinder  414  before it passes into toilet tank  420  via exit hole  425 . The flow rate of the chemical into mixing chamber  429  and, hence, the amount of chemical added to the water flow is preferably controlled by chemical flow control screw  445  as well as by the rate of water flow through dispensing mechanism  450 .  
         [0027]     As toilet tank  420  fills, the water flow slows and spring  413  pushes driving sleeve  435 , which is no longer compelled by the pressure of the water flow, back to the right until it catches end ring  439  of valve seal cylinder  414  and drives it until it covers entry holes  423  from chemical storage chamber  401 , thereby cutting off further entry of the chemical into dispensing mechanism  450  until the next time the toilet is flushed.  
         [0028]     Referring now to  FIG. 5 , there is shown a representation of a chemical dispenser for a flush toilet, referred to generally as  500 , constructed and operative in accordance with an additional preferred embodiment of the present invention. Chemical dispenser  500  is contained within chemical storage chamber  501  and is typically mounted on toilet tank  520  on an existing hole therein, as explained above with respect to the embodiment shown in  FIG. 1 . Chemical storage chamber  501  is connected to dispensing cup  529  via vertical chemical transfer tube  535 . Dispensing cup  529  is connected to toilet tank  520  via chemical exit tube  525  and air tube  545 .  
         [0029]     In the present preferred embodiment, chemical storage chamber  501  is airtight, including stopper  503 . As a result, when chemical dispensing cup  529  contains a measured dose of the chemical, as shown in the drawing, and the bottom end of vertical chemical transfer tube  535  is immersed in the chemical, no additional chemical will flow from chemical storage chamber  501  via chemical transfer tube  535  into dispensing cup  529 . Any time after the toilet has been flushed, the water level in toilet tank  520  is below the end of air tube  545  extending therein, and there is no air pressure to drive the chemical from dispensing cup  529  into toilet tank  520  via chemical exit tube  525 . As toilet tank  520  fills, the water level therein reaches the end of air tube  545  and continues to rise until toilet tank  520  is full. The water level in air tube  545  also rises, thereby compressing the air therein and in the upper portion of dispensing cup  529 . The increased air pressure in dispensing cup  529  drives the measured dose of chemical in the lower portion thereof out into toilet tank  520  via chemical exit tube  525 .  
         [0030]     With dispensing cup  529  emptied, the lower end of chemical transfer tube  535  is no longer immersed, and it is possible for air bubbles to rise via chemical transfer tube  535  and reach chemical storage chamber  501 . As a result, some of the chemical flows down chemical transfer tube  535  into dispensing cup  529  until the bottom end of vertical chemical transfer tube  535  is immersed in the chemical, thereby cutting off further flow of the chemical, as described above, and ensuring that a predetermined amount or dosage of the chemical will be stored in dispensing cup  529 . It should be noted that as the measured dose of chemical, which is determined by the volume of air in air tube  545  and the air pressure developed therein, as described above, flows out of dispensing cup  529 , chemical exit tube  525  will allow air pressure equalization in dispensing cup  529 , even though the end of air tube  545  in toilet tank  520  is immersed in water, so there will be no buildup of air pressure in dispensing cup  529 . Thus chemical dispenser  500  is in a stable state, with dispensing cup  529  containing the full measured dose of chemical, and toilet tank  520  is filled with water, until the next time the toilet is flushed.  
         [0031]     It will further be appreciated by persons skilled in the art that the scope of the present invention is not limited by what has been specifically shown and described hereinabove, merely by way of example. Rather, the scope of the present invention is defined solely by the claims, which follow.

Summary:
A chemical dispenser ( 100 ) for use with a flush toilet includes a chemical storage chamber ( 101 ) for a chemical which is to be added to the flushing water of the toilet, a mounting apparatus that allows the chemical dispenser to be easily mounted on an existing opening in the water storage tank ( 120 ) of the toilet, and a dispensing mechanism ( 150 ) that dispenses a predetermined quantity of the chemical into the flushing water of the toilet each time the toilet is flushed.