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CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to plumbing fixtures such as toilets. In particular, the present invention relates to the flush assembly and flush sequencing for toilets. 
     Conventional toilets utilize a single mechanical flush sequence to evacuate waste from the toilet bowl, rinse the bowl, and possibly to refill a water tank. Simple mechanical components such as gravity operated flapper valves and float controlled fill valves are normally used to control the passage of water through the bowl and the filling of the tank. The trade-off for such a simple mechanical flush assembly is wasted water consumption in low waste conditions and inadequate or inconsistent rinsing of the bowl in high waste conditions. 
     Over time there have been numerous revisions and improvements made to the conventional toilet. For example, several toilets have been devised with electronically controllable flush, rinse and fill components, see e.g., U.S. Pat. Nos. 5,548,850 and 6,332,229. These patents also disclose toilets with alternate flush sequences. And, more forceful rinsing action has been achieved using jet components, such as disclosed by U.S. Pat. No. 2,715,228. However, as of yet the flush control components and sequencing of conventional toilets has often been insufficient to achieve an efficient and adequate flush in varied waste load conditions. 
     There is thus a need for toilets with advanced flush assemblies and sequencing to better address problems with known toilets. 
     SUMMARY OF THE INVENTION 
     In one aspect the invention provides a toilet having a bowl with a bowl outlet and a rim having a rim outlet. A flush valve operates to control flow through the bowl outlet. A rim supply valve operates to control flow into the bowl rim. The toilet flushes water through the bowl during a flush sequence in which the rim supply valve and the flush valve are both opened and closed twice, first during a pre-rinse cycle and subsequently during a rinse cycle. The rim supply valve and the flush valve are closed at the beginning and end of the cycles and open therebetween. 
     In another aspect the invention provides a toilet as described that is selectively operable in first and second flush sequences. The first flush sequence includes a pre-rinse cycle in which the toilet flushes water through the bowl by opening and closing the rim supply valve and the flush valve once. The second flush sequence includes the pre-rinse cycle and a rinse cycle in which the rim supply valve and the flush valve are both opened and closed twice, first during the pre-rinse cycle and subsequently during the rinse cycle. 
     In still another aspect the invention provides a flush sequence for a toilet which includes initiating a pre-rinse cycle and subsequently initiating a rinse cycle for the same flush event. The pre-rinse cycle includes opening the supply valve to flow water to the rim and pass water through the rim outlet into the bowl, opening the flush valve to empty the bowl through the bowl outlet, and closing the flush valve. The rinse cycle includes opening the supply valve to flow water to the rim and pass water through the rim outlet to the bowl, opening the flush valve to evacuate the bowl through the bowl outlet, and closing the flush valve and the supply valve. 
     To improve flush performance, the flush sequence, particularly the rinse cycle, can further include using an eductor to increase the flow rate of rinse water into the bowl. 
     Additionally, the toilet can include an electronic control which controls the open and close operation of the flush valve and the rim supply valve. In addition to the rim water supply, the electronic control can control filling and output flow from a reservoir water supply, such as toilet tank. And, level sensors, such as mounted in the bowl and/or the water supply reservoir, can be coupled to the electronic control for sending bowl and reservoir level input signals to the electronic control, and thereby control fill levels in both. 
     Hence, the invention provides an advanced electronically controlled toilet which provides an improved flush. To save water in low-waste conditions, the toilet can be operated in a quick or short flush mode, in which the bowl is briefly rinsed by water from the bowl rim. For higher waste conditions, the user can select a long or dual rinse mode in which the bowl is pre-rinsed with water from the rim to empty the waste and then rinsed again, this time with rim water which may be eductor-assisted. To do this, the electronic control opens and closes the rim supply valve and the bowl flush valve one time during the pre-rinse cycle and a second time during the regular rinse cycle. Thus, fully opening and closing these valves twice during a single flush event. Additional electronic control and sensing can be provided to further automate and regulate the flushing operation. 
     The foregoing and still other advantages of the invention will appear from the following description. In that description reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration a preferred embodiment of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a toilet according to the present invention with its lid down; 
         FIG. 2  is a perspective view of the toilet of  FIG. 1  with its lid up; 
         FIG. 3  is a side view of the toilet with the bowl, the trapway, and the plumbing components shown in phantom lines; 
         FIG. 4  is a cross-sectional side view of the toilet taken along line  4 - 4  of  FIG. 1 ; 
         FIG. 5  is a cross-sectional side view of the toilet taken along line  5 - 5  of  FIG. 1 ; 
         FIG. 6  is a front lower left side view of some of the internal plumbing components of the toilet of  FIG. 1 ; 
         FIG. 7  is a simplified schematic of the plumbing of the toilet of  FIG. 1 ; 
         FIG. 8  is a process chart of a long flush sequence for the toilet of  FIG. 1 ; and 
         FIG. 9  is a process chart of a short flush sequence for the toilet of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1-5 , a toilet  10  is shown that is configured to have two flushing sequences. Although the specifics of the flushing sequences will be described in more detail below, an overview of the components of the toilet  10  and their connectivity will be described first to provide a structural context for the flushing sequences. Although a two-part modular construction is shown, it should be appreciated that the toilet  10  need not be of a modular design and could be of a more conventional toilet assembly. Accordingly, the modular assembly is only one example of a toilet that may utilize the flushing sequences described below. 
     As best seen in  FIGS. 1 and 2 , the toilet  10  includes a frontal basin portion  12  and a rear backpack portion  14 . In the embodiment shown, the toilet  10  is designed to be a modular assembly in which, generally speaking, the rear backpack portion  14  supports and/or houses many of the functional components of the toilet  10  while the frontal basin portion  12  is one of several possible front-side attachments which is adapted to be connected to the rear backpack portion  14 . As different front-side attachments may be made, the toilet  10  can take on various appearances using a single rear backpack portion  14 . Moreover, the rear backpack portion  14  may be configurable to receive various components that provide accessory functions to the toilet such as a bidet wand, automatic seat and/or lid lifting mechanisms, air circulating functions, music accessories, and so forth. 
     The frontal basin portion  12  includes a bowl  16  extending from a bowl rim  18  at the top of the bowl  16  to a bowl opening  20  proximate the bottom of the bowl  16 . The bowl rim  18  includes a channel  22  (best seen in  FIG. 4 ) which selectively receives water which may then be directed into the bowl  16  during a flushing sequence via apertures or rim openings in an underside of the bowl rim  18 . The bowl opening  20  may be placed in selective communication with a trapway  24  by a flush valve  26  that is located therebetween. 
     The flush valve  26  is electromechanically controlled by a control board  28  (e.g., a controller or electrical control, and as schematically illustrated in  FIG. 7 ) which is located in the rear backpack portion  14  of the toilet  10 . This control board  28  is electronically coupled to a motor  30  which is mechanically coupled to the flush valve  26  via a linkage  32  such as a belt or a chain. When the motor  30  drives the linkage  32 , the flush valve  26  may be actuated from an open position to a closed position or vise-versa. In the closed position, shown in  FIGS. 3 and 4 , an arcuate surface  34  of the flush valve  26  forms a seal about the bowl opening  20  at the bottom of the bowl  16  such that any water and waste contents located in the bowl  16  are substantially retained in the bowl  16 . Then, in the open position (not shown), the flush valve  26  is rotatably actuated from the close position to remove the seal between the bowl  16  and the trapway  24  such that the contents of the bowl  16  can pass from the bowl  16  into the trapway  24  such as during a flushing operation. Although a flush valve  26  that is rotatable is shown, other types of valves could also be used to selectively place the bowl  16  in fluid communication with the trapway  24 . 
     The trapway  24  is a tube-like passage that snakes under the bowl  16  and rearwards in a sideways S-shape from the bowl opening  20  to a trapway end  36  which connects to an opening in the floor which connects to a waste line pipe (not shown) or the like. The geometry of the trapway  24  is such that a first leg  38  of the trapway  24  proximate the flush valve  26  extends downward to a dip  40 , a second leg  42  of the trapway  24  extends upward from the dip  40  to a weir  44 , and a third leg  46  of the trapway  24  extends downward from the weir  44  to connect to the opening in the floor. To prevent the escape of trapped sewer gases from the waste water line into the bowl  16  (and into the atmosphere surrounding the toilet  10 ), water may be captured in the space between the dip  40  and the weir  44  to form a water seal in the trapway  24 . 
     A water level sensor  48  (schematically illustrated in  FIG. 7 ) may also be coupled to the bowl  16  to detect a level of the water in the bowl  16 . The water level sensor  48  may be electronically coupled to the control board  28  to indicate the current state of water in the bowl  16  (e.g., a water level of the bowl  16 ) via a signal. The water level sensor  48  may be utilized to detect the water level in the bowl  16  and to stop the feeding of water to the bowl  16  during a flush sequence during a fill step or in the event that a blockage in the trapway  24  or the like prevents water from emptying from the bowl  16 . 
     Now with additional reference to  FIGS. 5 ,  6 , and  7 , the rear backpack portion  14  supports and houses the plumbing utilized in performing the flushing sequences. Beginning at the source, a water supply  50  (illustrated schematically in  FIG. 7 ) provides water to the other plumbing components. The water supply  50  is connected with the toilet  10  via an inlet line  52  that comes in from the behind the rear backpack portion  14  of the toilet  10 . The inlet line  52  is connected to a solenoid valve  54 . The solenoid valve  54  may be electronically controlled by the control board  28 , to selectively place the inlet line  52  in fluid communication with a tank  56  via a tank fill line  58  (i.e., a filler) or the bowl rim  18  via a rim line  60 . The rim line  60  is placed in fluid communication with the bowl rim  18  via a spud connection or the like at an end  68  of the rim line  60 . Although a single solenoid valve  54  is shown in  FIGS. 3 to 6 , a separate rim supply valve  54   a  and fill valve  54   b  may also be used as illustrated in the schematic of  FIG. 7 . 
     Notably, the tank  56  (or water supply reservoir) is also placed in communication with the rim line  60  via an eductor line  62  which connects to the rim line  60  to form an eductor  64 . This eductor  64  may assist in providing a particularly strong flow of water to the rim  18  when water from the tank  56  supplements the water being supplied via the rim line  60 . 
     Additionally, a float switch  66  may be located in the tank  56 . When the water level in the tank  56  exceeds a pre-determined threshold level, typically causing a portion of the float switch  66  to rise within the tank  56 , this displacement of a portion of the float switch  66  may cause the closing of a shutoff valve (possibly either by a direct mechanical connection between the float switch  66  and the shutoff valve or by a sending an electrical signal to the control board  28  which operates the shutoff valve) which temporarily closes off the water supply  50  from the other plumbing components. 
     With reference to  FIG. 7 , a summary of the connectivity of the control board  28  to the various components may be made. With respect to the bowl  16 , the control board  28  may be electrically coupled to the water level sensor  48  and the motor  30  that controls the open or closed state of flush valve  26 . With respect to the plumbing components in the rear backpack portion  14 , the control board  28  is electrically coupled to the solenoid valve  54  (illustrated in  FIG. 7  as separate rim supply valve  54   a  and fill valve  54   b ) which controls the flow of water from the water supply  50  into the tank  56  and into the rim  18 . Further, the control board  28  may receive a status of the state of the water level in the tank  56  via the float switch  66 . Although not previously described, the control board  28  is also electronically coupled to a short flush button  70  and a long flush button  72 . Of course, rather than being buttons, these could be any of a number of types of controls, switches, buttons, or the like. The short flush button  70  and the long flush button  72  may be used to start a short flushing sequence or a long flushing sequence that will now be described. 
     Referring now to  FIG. 8 , a long flush sequence  800  is shown. The long flush sequence  800  is initiated when the long flush button  72  is pressed according to step  802 . Once the control board  28  detects the operation of the long flush button  72 , the control board  28  instructs the various components to perform a pre-rinse, rinse, and fill of the bowl  16 . 
     The pre-rinse cycle begins with the control board  28  instructing the rim supply valve  54   a  to open and then close according to step  804  to pre-rinse the bowl  16 . This pre-rinse cycle may remove debris, such as toilet paper, stuck on the walls of the bowl  16  above the water fill line. Only a small of amount of water may be used to perform the pre-rinse of the bowl  16 . 
     Next, according to step  806 , the flush valve  26  is opened to remove waste from the bowl  16  while the rim supply valve  54   a  remains closed. This is a short, water efficient step, which removes the waste from the bowl  16 . The flush valve  26  is then closed to seal the bowl opening  20  of the bowl  16  according to step  808 . 
     Once the pre-rinse cycle is completed, the rinse cycle begins. After the flush valve  26  closed, the rim supply valve  54   a  is opened according to step  810  to start the bowl rinse cycle. After a sufficient amount of water has been introduced into the bowl  16 , the flush valve  26  is opened according to step  812  to evacuate the water accumulated during the rinse cycle from the bowl  16 . While the flush valve  26  is opened, water may continued to be supplied to the rim  18  to rinse the bowl  16 . After a period of time, the flush valve  26  is closed according to step  814  to seal the bowl  16  and the rim supply valve  54   a  is closed according to step  816  to end the bowl rinse cycle. 
     Notably, while the rim supply valve  54   a  is opened and supplying water to the rim  18  via the rim line  60  either during the pre-rinse cycle or the rinse cycle, the eductor  64  may be used to increase the rate at which water is supplied to the rim  18 . As the water introduced from the tank  56  to the rim line  60  via the eductor line  62  increases the flow rate of the rinse water into the bowl rim  18 , the water is supplied more quickly and in such a manner as to more effectively and efficiently rinse the bowl  16 . At greater flow rates, better bowl rinsing can be performed more quickly and with less water than with eductor-less flush mechanisms. 
     After the bowl rinse cycle is complete, then the fill cycle begins to refill the bowl  16  for another use of the toilet  10 . During the fill cycle, the fill valve  54   b  is open and then closed according to step  818  to supply water to the water tank  56  (which may have been partially or fully depleted during the pre-rinse and rinse cycles) and to re-fill the bowl  16 . The fill valve  54   b  remains open until the bowl  16  and the tank  56  are refilled. The determination of the levels of water in the bowl  16  and tank  56  may be determined by the water level sensor  48  and the float switch  66 , respectively. Of course, a stop condition for refilling the bowl could potentially be based on one of or both of the water level sensor  48  and the float switch  66  or could be based on some other sensor or timing mechanism. 
     It should be appreciated that during the fill cycle, the rim supply valve  54   a  may be closed and, accordingly, the rate of flow of water into the bowl  16  may be comparatively slower than during the pre-rinse and/or rinse cycle. Of course, depending the particular plumbing configuration, the bowl re-fill may be accomplished using an additional bowl fill valve or by using the rim supply valve  54   a  either alone or in combination with the fill valve  54   b.    
     Referring now to  FIG. 9 , a short flush sequence  900  is illustrated which may be generally used for the elimination of light or low waste, such as urine or perhaps small amounts of bath tissue, from the bowl  16 . Upon pressing the short flush button  70  according to step  902 , the short flush sequence  900  is initiated. First, a pre-rinse cycle occurs in which the rim supply valve  54   a  is open and then closed according to step  904  to supply a shot of water to the rim  18  and clear any waste or debris from the walls of the bowl  16 . Next, the flush valve  26  is opened to remove the water and waste from the bowl  16  via the trapway  24  according to step  906 . After the water and waste are eliminated from the bowl  16 , the flush valve  26  is closed according to step  908 . The fill valve  54   b  is then open and closed to re-fill the water in the bowl  16  and the tank  56  according to step  910 . Of course, as described above, the re-fill step may be achieved by opening the fill valve  54   b  or by opening one or more other valves to fill the tank  56  and bowl  16 . 
     Thus, a toilet is disclosed that is capable of performing two flush sequences. The longer of the two flush sequences is engineered with the removal of solid waste or the like from the bowl. The shorter of the two flush sequences is engineered with the removal of light waste or the like from the bowl. Given the benefits of water conservation, these flush sequences aim to use an appropriate amount of water for the task at hand. 
     Further, these flush sequences may utilize a pre-rinse cycle which helps to more efficiently use the water of the flushing sequence. In contrast to conventional flush cycles, which may have water continuously fed to the bowl via the rim while water continually drains from the bowl opening, the rim supply valve  54   a  may be opened and closed to provide an initial shot of water to pre-rinse the walls and then opened again after the bowl has been evacuated. By shutting off the rim supply valve in between the pre-rinse cycle and the subsequent rinse cycle, the amount of water used over the flush cycle is reduced. 
     While a specific embodiment of the present invention has been shown, various modifications falling within the breadth and scope of the invention will be apparent to one skilled in the art. For example, one or more jets may assist in vacating water and waste from the bowl. Thus, the following claims should be looked to in order to understand the full scope of the invention. 
     INDUSTRIAL APPLICABILITY 
     Disclosed is a plumbing fixture, such as a toilet having an advanced flush control assembly and sequencing providing efficient water consumption with adequate rinsing of the bowl.

Summary:
A toilet has an electronic flush assembly operable in either a short or long flush sequence selectable by a user. The long flush sequence includes a pre-rinse cycle and a rinse cycle in which the a supply valve and a flush valve are both opened and closed twice, once each first during the pre-rinse cycle and again during a subsequent rinse cycle. The rim supply valve and the flush valve are opened during the pre-rinse and rinse cycles but are closed at the start and end of each cycle. An electronic control controls operation of the valves as well as water supply control components. Level sensors can also be included to provide feedback to the controller, for example, to prevent overflow conditions.