Abstract:
A waste removal system that includes a toilet pan ( 28 ) for a ultra-low flushing volume toilet ( 20 ). The pan ( 28 ) includes a rearward end ( 28   a ) adapted for positioning substantially adjacent a cistern ( 22 ) and a frontward end ( 28   b ) adapted for positioning substantially remote the cistern ( 22 ). The pan ( 28 ) also includes a flushing water outlet having a primary outlet nozzle arrangement ( 42 ) disposed substantially adjacent the pan frontward end ( 28   b ) and adapted to direct flushing water ( 62 ) downwards and towards the pan rearward end ( 28   a ). The system also includes a related flushing method and drainline ( 90 ).

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to a waste removal system and more particularly to a ultra-low flushing volume toilet and a related toilet pan, flushing method and drainline.  
         [0002]     The expression “ultra-low flushing volume” is herein defined as having nominal full and reduced flush volumes of about 3 litres and 2 litres respectively.  
       BACKGROUND OF THE INVENTION  
       [0003]     The design of water closets (WCs) in Australia has been greatly influenced by the need to minimise water consumption and maintain an adequate sanitation system to safe guard and maintain a high level of public health.  
         [0004]     Since 1982 reductions in Australian WC flushing volume have lead to a major lowering of the average daily WC water consumption per person from 55 litres to 18 litres. A major contribution to this reduction was the development of the two button, dual flush WC having 6/3 litre reduced flush technology which gave the user the choice of applying either a 6 litre full flush or a 3 litre reduced flush option to operate the WC.  
       OBJECT OF THE INVENTION  
       [0005]     It is an object of the present invention to provide a toilet and related componentary that can operate directly into a sewer with a ultra-low flushing volume.  
       SUMMARY OF THE INVENTION  
       [0006]     Accordingly, in a first aspect, the present invention provides a toilet pan for a ultra-low flushing volume toilet, the pan including: 
        a rearward end adapted for positioning substantially adjacent a cistern;     a frontward end adapted for positioning substantially remote the cistern; and     a flushing water outlet having a primary outlet nozzle arrangement disposed substantially adjacent the pan frontward end and adapted to direct flushing water downwards and towards the pan rearward end.        
 
         [0010]     The pan preferably also has a S-bend outlet trap with a pan end and sewer end and the primary outlet nozzle arrangement is also adapted to direct flushing water towards and/or into the S-bend pan end.  
         [0011]     The S-bend pan end includes a substantially straight pipe section and the primary outlet nozzle arrangement is also adapted to direct flushing water substantially parallel to the longitudinal axis of the pipe section.  
         [0012]     A majority of the flushing water is preferably directed to the primary outlet nozzle arrangement.  
         [0013]     The primary outlet nozzle arrangement preferably includes a plurality of outlet nozzles.  
         [0014]     The pan preferably also has a secondary outlet nozzle arrangement, most preferably in the form of a single nozzle, disposed substantially adjacent the pan rearward end and adapted to direct a minority of the flushing water substantially downwards.  
         [0015]     The pan preferably also has tertiary outlet nozzle arrangements, most preferably in the form of holes, disposed along the sides of the pan and adapted to direct a minority of the flushing water substantially downwards.  
         [0016]     The pan preferably includes a rear wall leading to the S-bend and the secondary outlet nozzle arrangement is adapted to direct flushing water downwards along the rear wall.  
         [0017]     The minority of the flushing water is preferably directed to the secondary outlet nozzle arrangement.  
         [0018]     The pan preferably includes a manifold adapted for fluid communication with a flushing outlet of the cistern and the primary or the primary and secondary outlet nozzle arrangements. The manifold preferably substantially replicates the shape of upper rim of the pan.  
         [0019]     In one form, the manifold is formed separately from the pan and is preferably releasably engageable therewith. In another form, the manifold is formed integrally with the pan. In a further form, the manifold is formed integrally with the toilet seat.  
         [0020]     In a second aspect, the present invention provides a method of flushing a toilet pan for a ultra-low flushing volume toilet, the pan having a rearward end adapted for positioning substantially adjacent a cistern and a frontward end adapted for positioning substantially remote the cistern, the method comprising directing a majority of a cistern&#39;s flushing water in a concentrated jet from the upper forward end of the pan towards the lower rearward end of the pan in a direction substantially aligned with the frontward-to-rearward centreline of the pan.  
         [0021]     The method preferably also comprises directing a minority of a cistern&#39;s flushing water from the upper rearward end of the pan along a rear wall of the pan end towards the lower rearward end of the pan.  
         [0022]     The method preferably also comprises directing a minority of a cistern&#39;s flushing water down the sides of the pan.  
         [0023]     The method preferably also comprises inducing a partial syphon action into the waste outlet of the pan by directing the majority of a cistern&#39;s flushing water directly into the pan outlet in a direction substantially parallel to the longitudinal axis of the leading section of the pan outlet, whereby the partial syphon action lowers the level of the water in the pan during the commencement of the flush.  
         [0024]     In a third aspect, the present invention provides a toilet pan for a ultra-low flushing volume toilet, the pan comprising: 
        a flushing outlet; and     an outlet trap in fluid communication with the flushing outlet, the outlet trap comprising a first downwardly concave lower bend and a second upwardly convex upper bend,     wherein the pan cross-sectional shape at an upper level horizontally aligned with the upper surface of the first bend defines a first relatively larger cross-sectional area and the pan&#39;s cross-sectional shape at a lower level horizontally aligned with the lower surface of the second bend defines a second relatively substantially smaller cross-sectional area.        
 
         [0028]     Preferably, the first cross-sectional area is approximately double the size of the second cross-sectional area.  
         [0029]     The pan preferably has a substantially vertical rear wall section with a lower edge substantially adjacent the first cross-sectional area. The rear wall is preferably upwardly angled from the rear of the pan at about 0 to 10 degrees from horizontal.  
         [0030]     The pan preferably has a front wall section between the first and second cross-sectional areas, the front wall section having an upper relatively steeply angled portion, a lower portion substantially parallel to and displaced rearwardly from the upper portion and an intermediate relatively shallowly angled portion therebetween.  
         [0031]     The geometric centre of the first cross-sectional area is preferably substantially horizontally aligned with a user&#39;s solid drop position. The second cross-sectional area is preferably wholly rearward of the solid drop position.  
         [0032]     In a fourth aspect, the present invention provides a drainline for a ultra-low flushing volume toilet, the drainline characterised by a height-to-width ratio between about 1.4:1 to 1.5:1 and an upper radius-to-lower radius ratio of about 3:1.  
         [0033]     The drainline in preferably produced from extruded plastics material. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]     Preferred embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings in which:  
         [0035]      FIG. 1  is a cross sectional side view of a first embodiment of a toilet suite incorporating aspects of the invention;  
         [0036]      FIG. 2  is a front view of the suite shown in  FIG. 1 ;  
         [0037]      FIG. 3  is a perspective view of the suite shown in  FIG. 1 ;  
         [0038]      FIG. 4  is a cross sectional side view of a second embodiment of a toilet suite incorporating aspects of the invention;  
         [0039]      FIG. 5  is a front view of the suit shown in  FIG. 4 ;  
         [0040]      FIG. 6  is a perspective view of the suit shown in  FIG. 4 ;  
         [0041]     FIGS.  7  to  17  are perspective views of examples of outlet nozzle arrangements; and  
         [0042]      FIG. 18  is an end view of an embodiment of a drainline incorporating an aspect of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]     Referring firstly to FIGS.  1  to  3 , there is shown a first embodiment of a toilet suite  20  incorporating aspects of the invention. The suite  20  generally comprises a full and reduced flushing volume cistern  22  (known as a flush tank in the United States) operated by a pair of button actuators  24 , which are accessible through the top surface of a cistern body  26 . The cistern  22  is placed within the larger cistern body  26  as, due to its ultra-low flushing volume, it would appear out of scale (ie. too small) with the remainder of the toilet suite  20 .  
         [0044]     The suite  20  also comprises a pan  28  connected to the cistern  22  by a flush pipe  30 . A toilet seat  32  and lid  34  are pivotally mounted to the pan  28  by hinges, which are well known. The pan  28  has a rearward end  28   a  and a frontward end  28   b  and a rim  36  about an opening  38 .  
         [0045]     A flushing water manifold  40  is located beneath the rim  36  and is in fluid communication with the flush pipe  30 . The manifold  40  has a primary outlet nozzle arrangement  42  positioned near the frontward end  28   b  of the cistern  28  and a smaller secondary outlet nozzle arrangement, in the form of single nozzle  44 , positioned adjacent the rearward end of the pan  28   a.  The primary outlet nozzle arrangement  42  has four outlet nozzles  46 , which are best seen in  FIG. 7 . The manifold  40  also has a number of tertiary outlet nozzle arrangements, in the form of holes  48 , disposed along the sides of the pan  28 .  
         [0046]     In the preferred embodiment shown, the manifold  40  is a separate, substantially oval shaped plastic component that substantially replicates the shape of the pan rim  36 . In other embodiments (not shown), the manifold is formed integrally with the pan or with the toilet seat.  
         [0047]     The pan  28  also includes a flushing outlet  50  which is connected to a mains sewerage system in a known manner. The flushing outlet  50  is preceded by an S-bend outlet trap  51  formed from a first downwardly convex lower bend  52  and a second upwardly convex upper bend  54 . The pan  28  also has a rear wall  56  which is upwardly angled from the rear of the pan  28  at about 10° from horizontal. The front wall  58  of the pan  28  has an upper relatively steeply angled portion  58   a,  lower relatively steeply angled portion  58   b,  which is substantially parallel to and rearwardly displaced from the upper portion  58   a,  and an intermediate relatively shallowly angled portion  58   c  therebetween. The portion of the pan  28  adjacent the lower front wall portion  58   b  is substantially cylindrical and has a central longitudinal axis  60 .  
         [0048]     The operation of the suite  20  will now be described. Pressing one of the actuator buttons  24  initiates flushing of the suite  20 . The flushing water is communicated from the cistern  22  to the flush pipe  30  and so to the flushing water manifold  40 . The majority of the flushing water (approximately 80%) exits the manifold  40  via the four nozzles  46  in the primary outlet arrangement  42 , as indicated by the large arrow  62  and is directed towards the commencement of the S-bend outlet trap  51  in a direction substantially parallel with the axis  60  of the cylindrical portion of the pan  28  adjacent the front wall lower portion  58   b.  Directing the flushing water  62  in this way concentrates the energy of the flushing water into the outlet trap  51  and results in adequate clearing of waste (equal to or better than current standards for known 6/3 litre full/reduced flush toilet suites) within the pan  28  with the 3/2 litre ultra-low flushing volumes. A minority of the flushing water is directed through the outlet  44 , as indicated by medium arrow  64 , to wet and clean the rear wall  56  of the pan. An even smaller amount of the flushing water is directed out of the holes  48  as indicated by small arrows  66  to wet and clean the sides of the pan  28 .  
         [0049]     The water level in the pan  28  in the absence of a flush is denoted  68  in  FIG. 1 . During the previously described flushing action, the energy of the majority of the flushing water  62  creates a partial syphoning action within the outlet trap  51  which results in the water level during the flush falling to approximately that denoted  70 . The surface area at the level  70  is approximately half that at the level  68  and the corresponding reduction in cross sectional area of the outlet trap  51  further increases the velocity, and thus concentrates the energy, of the flushing water through the trap  51 , further aiding in waste clearance. The larger surface area at the water level  68  also advantageously provides a larger target area for user&#39;s wastes, particularly solid wastes. Further advantageously, the geometric centre of the surface area of the water at level  68  is substantially vertically aligned with the approximate solid waste drop position of a user.  
         [0050]     Accordingly, before flushing, the pan  28  advantageously provides a large target surface area (at level  68 ) to minimise the likelihood of waste being incident on non wetted regions of the pan  28 . During flushing, the pan  28  advantageously provides a reduced surface area (at level  70 ) to concentrate the energy of the flushing water. This combination also contributes to the improved clearing of waste in the pan  28  with ultra-low flushing volumes.  
         [0051]     FIGS.  4  to  6  show a second embodiment of suite  80  incorporating aspects of the invention which is similar to the suite  20  described with reference to FIGS.  1  to  3  and in which like reference numerals are used to indicate like features. The difference between the suite  80  and  20  is the suite  80  has a hand washing basin  82  integrally formed with the cistern body  26 . After flushing, the mains water used to fill the cistern  22  is directed to a free outlet tap  84  whereafter it flows from the basin  82  through a pipe  84  and into the cistern  22 . This arrangement provides further reductions in overall water usage by allowing a user to wash their hands with water that is then reused as flushing water rather than washing their hands in water that is directly returned to the sewer.  
         [0052]      FIG. 7  is an enlarged detailed view of the preferred form of primary outlet nozzle arrangement  42 .  FIGS. 8 through 17  are similar views of other primary outlet nozzle arrangements  42  with outlet nozzles  46 .  
         [0053]     The primary outlet nozzle arrangement  42  shown in  FIG. 17  is the most preferred and is formed from upper and lower moulded halves  42   a  and  42   b  respectively. The outlets  46  each receive a separate portion of the flushing water from either side of the manifold  40 . This reduces the turbulence, and energy loss, of the two streams of water hitting each other during entry to the primary outlet nozzle arrangement  42 , compared to earlier embodiments shown in FIGS.  7  to  15 . Further, the outlets  46  include upper, lower and side edges  46   a,    46   b  and  46   e  respectively which are shaped to form the flow of flushing water (as exemplified by the arrow  62  in  FIG. 1 ) into a cross sectional shape similar to that of the surface of the water in the pan  28  at level  68 . Directing and shaping the flushing water  62  to cover all of the water surface at level  68  serves to maximise the amount of waste that is directed into the waste S-bend outlet trap  51  and out through the flushing outlet  50 . Concentrating and directing the energy of the flushing water  62  into the trap  51  in this way improves waste clearance.  
         [0054]      FIG. 18  is an end view of a drainline  90  suitable for use with the ultra-low flushing volume toilet suites described above. The drainline  90  is characterised by an internal height H to width W ratio between about 1.4:1 and 1.5:1 and an internal upper radius R to lower radius r ratio of about 3:1. It has been found that these ratios provide a drainline with an optimum balance between waste transportation at low flow rates (less than 2.5 litres/second) due to increased flow velocity in the lower (and slimmer) portion of the drainline  90  and total capacity at high flow rates. The preferred size of the drainline  90  is an internal height H of 130 mm, internal width W of 90 mm, upper internal radius R of 45 mm and lower internal radius r of 15 mm.  
         [0055]     When the suites 20 and 80 were matched with the drainline  90 , and their performance benchmarked against an industry leading 6/3 litre dual flush toilet suite, the following results were obtained from a comparison of potable water usage and savings for the suites  20 ,  80  and the 6/3 litre dual flush WC based on daily water usage per person of five flush cycles (one full flush and four reduced flush cycles).  
                                               Daily water   Average flush   Percentage       WC system   usage per person   volume   saving                   6/3 litre dual flush     18 litres    3.6 litres   ˜       (benchmark)       Suite 20     11 litres    2.2 litres   39%       Suite 80   9.38 litres   1.88 litres   48%                  
 
         [0056]     Although the invention has been described with reference to preferred embodiments, it will be appreciated by those skilled in the art that the invention is not restricted to such preferred embodiments. For example, the invention is also suitable for use with pans that have a P-bend outlet trap.