Abstract:
The apparatus and method of the invention provides for a rinse valve for controlling the flow of rinse fluid to a vacuum waste receptacle. The rinse valve comprises a primary rinse fluid flow path and a poppet assembly intersecting the primary rinse fluid flow path. The rinse valve also comprises a solenoid-driven fluid control device having a solenoid armature movable between an inactive state in which the armature engages the poppet assembly to block flow of the rinse fluid through a poppet channel and an active state in which the solenoid armature is disengaged from the poppet assembly to allow flow of the rinse fluid through the poppet channel to raise the poppet assembly, permitting the flow of the rinse fluid through the primary rinse fluid flow path and out of the valve, the armature being located at all times out of the primary flow path of the rinse fluid.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application No. 61/102,653, filed Oct. 3, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention generally pertains to vacuum waste systems and, more particularly, to rinse valves for vacuum waste receptacles such as vacuum toilets. 
       BACKGROUND OF THE INVENTION 
       [0003]    Vacuum waste systems are generally known in the art for use in transportation vehicles such as airlines. Vacuum waste systems typically comprise a waste receptacle connected by a vacuum line to a waste tank. When a flush valve connected to the waste receptacle opens, the contents of the waste receptacle are removed by differential pressure to the waste tank. Generally, rinse fluid is delivered to the waste receptacle via nozzles to assist in the ease of waste removal and to clean the walls of the waste receptacle. 
         [0004]    Conventional rinse valves for controlling the flow of aqueous rinse fluid to vacuum waste receptacles are generally known. Rinse valves are actuated when a command is initiated from a user input device such as a flush button. Such rinse valves often use solenoid actuated armature arrangements to control the flow of rinse fluid to the waste receptacle. 
         [0005]    In typical designs for solenoid-actuated rinse valves the solenoid armature is disposed directly in the main flow path of the rinse fluid. Such prior systems present reliability problems because the substantial wetting of the armature with the rinse fluid combined with the draining of rinse fluid from adjacent the armature during servicing causes the build-up of mineral deposits on the surfaces of the armature and its housing. The friction produced by this mineral build-up initially tends to cause higher current draw to the solenoid in order to move the armature over a deposit-roughened surface. Over time, the mineral build-up may become so great that the armature may seize in the open or closed position. A rinse valve with an armature seized in the closed position will not provide rinse fluid to a toilet while a rinse valve with an armature seized in the open position will cause flooding of the lavatory area. In addition, bearing and shearing stresses on the armature and housing surfaces due to friction from mineral build-up contribute to galling and flaking of surface plating as well as contamination from micro-particles. A need therefore exists for an improved rinse valve and method for controlling the flow of rinse fluid to vacuum waste receptacles such as vacuum toilets. 
         [0006]    Under certain circumstances a rinse valve may be exposed to very cold temperatures for a prolonged period of time. If prolonged cold exposure and inactivity occur, and the rinse fluid is not drained or is incompletely drained from the rinse valve, it is not uncommon for frozen rinse fluid to form within the rinse valve. In a conventional rinse valve, the expansion of the frozen rinse fluid inside of the valve may crack or otherwise damage the valve. A need therefore exists for an improved rinse valve and method for providing protection against damage caused by rinse fluid freezing within the rinse valve. 
       BRIEF SUMMARY OF THE EMBODIMENTS 
       [0007]    The invention is generally directed to providing improved efficiency and reliability in controlling the flow of rinse fluid for the operation of vacuum waste receptacles. The apparatus and method of the invention achieve this by way of a solenoid-operated valve with its armature disposed out of the primary flow path of the rinse fluid. This design dramatically reduces the likelihood that the armature and its housing will develop surface mineral deposits during use. Since armatures typically slide in the housing between open and closed positions, the resulting dramatic reduction in mineral roughening of the sliding surfaces results in significantly less wear stress on the valve and less contamination of the valve due to flaking and galling of rubbing surfaces. This increases the reliability and longevity of the valve and reduces the likelihood of a failure. 
         [0008]    The valve design of the present invention relies upon differential fluid pressure in controlling the flow of rinse fluid through the valve. The use of differential fluid pressure in the valve design reduces the size required for the solenoid and provides for less current draw during operation of the armature than would otherwise be necessary. The valve also provides the unique teaching of self-venting, self-draining and freeze protection features in a single rinse valve block having a central solenoid-operated valve. 
         [0009]    The rinse valve of the present invention thus includes a valve block having an inlet for receiving aqueous rinse fluid, primary and a secondary rinse fluid flow paths, and an outlet for providing rinse fluid to a waste receptacle or toilet. An inlet venting assembly is disposed in the valve block, a solenoid/poppet fixture is provided to control the flow of the rinse fluid in the primary flow path, and a vacuum breaker outlet assembly is disposed in the valve block downstream of the solenoid/poppet fixture. 
         [0010]    The present invention includes an inlet venting assembly having a sleeve valve mounted between an expansion chamber and an inlet cavity that provides protection against damage due to freezing of rinse fluid inside of the valve. Upward movement of the sleeve valve into the expansion chamber accommodates the expanding volume taken up by any formation of freezing rinse fluid forming in the inlet cavity. This feature provide substantial protection against damage caused by rinse fluid freezing in the rinse valve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The above-noted and other advantages of the invention will be apparent from the description of the invention provided herein with reference to the attached drawings in which: 
           [0012]      FIG. 1  is a perspective view of the outside of a rinse valve in accordance with the present invention; 
           [0013]      FIG. 2  is a cross-sectional view of the valve of  FIG. 1 , taken along lines  2 - 2  of  FIG. 1 ; 
           [0014]      FIG. 3  is cross-sectional view of the valve of  FIG. 1 , taken along lines  2 - 2 , showing the inlet venting assembly in the closed position and the armature of the solenoid/poppet fixture in the closed position; 
           [0015]      FIG. 4A  is a view of a portion of the valve shown in  FIG. 3 ; 
           [0016]      FIG. 4B  is an exploded view of a portion of the solenoid/poppet fixture shown in  FIG. 4A ; 
           [0017]      FIG. 5  is cross-sectional view of the valve of  FIG. 1 , taken along lines  2 - 2 , showing the flow path of the rinse fluid when the armature of the solenoid/poppet fixture is in the open position and the vacuum breaker outlet assembly is in the closed position; 
           [0018]      FIG. 6  is a cross sectional view of a portion of the valve of  FIG. 1 , taken along lines  2 - 2 , showing the armature in the open position and the poppet of the solenoid/poppet fixture in the closed position; 
           [0019]      FIG. 7  is a perspective view of the sleeve of the sleeve valves used in the embodiment of the invention illustrated in  FIG. 1 ; and 
           [0020]      FIG. 8  is a cross-sectional view of a portion of the rinse valve of  FIG. 1 , taken along lines  8 - 8 , showing the vacuum breaker outlet assembly of the rinse valve. 
           [0021]      FIG. 9  is a cross-sectional view of the valve of  FIG. 1 , corresponding to  FIG. 2  in which the inlet venting assembly has moved into the expansion chamber and the armature of the solenoid/poppet fixture is in the closed position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    The embodiment of the invention described below is not intended to be exhaustive or to limit the invention to the precise structure and operation disclosed. Rather, the embodiment described below has been chosen and described to explain the principles of the invention and its application, operation and use in order to best enable others skilled in the art to follow its teachings. 
         [0023]    This invention is generally directed to a valve and method of controlling the flow of rinse fluid to vacuum waste receptacles, such as vacuum toilets and vacuum sinks which form part of a vacuum waste collection system in an aircraft. Turning now to the figures, the rinse valve  10  of the present invention includes an inlet venting assembly  12 , a solenoid/poppet fixture  14  and a vacuum breaker outlet assembly  16  all mounted in a valve block  17 . 
         [0024]    As shown in  FIG. 2 , inlet venting assembly  12  includes an inlet cavity  18  into which an inlet fitting  20  is attached by suitable means. Aqueous rinse fluid will enter the rinse valve through a conduit  21  in inlet fitting  20 , passing through an optional filter screen  22  located within the inlet cavity. The filter screen  22 , sometimes referred to as a “bug screen,” is United States Public Health Service compliant. The rinse fluid is preferably potable, although grey water may be used with this rinse valve if desired. Also, the rinse fluid may contain cleaning chemicals, if desired. 
         [0025]    A sleeve valve  24  is mounted between an expansion chamber  27  and a sleeve valve cavity  26  that is opposite inlet cavity  18 . Sleeve valve cavity  26  is in fluid communication with the inlet cavity  18 , as shown for example in  FIG. 2 . Sleeve valve  24  comprises a sleeve  25  and a sleeve supporting member  28  mounted above the sleeve valve cavity  26 . Sleeve  25  is supported within sleeve valve cavity  26  by the supporting sleeve member. Also, supporting sleeve member  28  has a vent opening  30  in communication with the atmosphere outside of the rinse valve. 
         [0026]    Supporting sleeve member  28  has a cylindrical cavity for slidably receiving the sleeve  25 . As shown in  FIG. 7 , sleeve  25  has an upper cylindrical portion  32 , a lower cylindrical portion  34 , and a partition  36  for blocking fluid flow between the cylinders. The peripheral walls of the cylinders have a plurality of ports  40 ,  42  extending through the walls. Also, an annular ledge  37  encircles the partition and extends outwardly from the cylindrical portions. An “O” ring  38  is positioned about the upper cylindrical portion  32  on top of the ledge  37 . Although,  FIG. 7  illustrates nearly identical sleeves of both the inlet venting assembly  12  and the vacuum breaker outlet assembly  16 , it should be noted that the sleeve  25  of the inlet venting assembly  12  has only one “O” ring  38 , whereas the sleeve of the vacuum breaker outlet assembly  16  includes two “O” rings  138 ,  139 . 
         [0027]    When there is no incoming rinse fluid pressure, sleeve  25  is biased so as to be maintained in the open position illustrated in  FIG. 2  by a spring  46 . In this position the sleeve valve is open so that air may flow from vent opening  30  past wall ports  40 ,  42  to the inlet cavity  18  and conduit  21 . When the rinse fluid entering inlet cavity  18  exceeds a predetermined threshold value, sleeve  25  will slide up into supporting sleeve member  28 , closing the sleeve valve  24  by way of the sealing engagement of “O” ring  38  against the bottom edge  44  of supporting sleeve member  28  thereby closing off access to port  30 . Accordingly, the rinse fluid passes through inlet cavity  18  into sleeve valve cavity  26 . Under normal conditions (non-freezing), the force of the rinse fluid is not great enough to move the sleeve  25  and the sleeve supporting member  28  upwardly against the biasing force provided by the spring  47  on the sleeve supporting member  28 . 
         [0028]      FIG. 3  illustrates sleeve valve  24  in an upward closed position, permitting rinse fluid to flow into the sleeve valve cavity  26 . On its way to this closed position, the sleeve valve will permit air in the system to escape. Finally, it should be noted that sleeve valve  24  may be replaced by other valve types that function comparably such as a float valve. 
         [0029]    The rinse fluid moving past the closed sleeve valve  24  ( FIG. 3 ) enters a first channel  204  and flows toward solenoid/poppet fixture  14 . As shown in  FIG. 2 , this fixture includes a solenoid  52  and an armature  60  which moves within a pressure tube  54  to control the flow of the rinse fluid through the rinse valve in response to activation of the solenoid when the toilet is flushed. Solenoid  52  includes solenoid coils  56  disposed within a coil housing  58  and encircling the pressure tube. The armature  60  is positioned snugly and slideably within the pressure tube for movement upwardly against the bias of a spring  62  in response to activation of the solenoid coils. In a preferred embodiment, the armature may include a preferably rubber-type surface  64  at its distal end designed to engage a resilient poppet member  90 , which will be described below. Other suitable surfaces may also be provided. As also explained below, because the armature  60  of the solenoid/poppet fixture is outside of the primary flow path of the rinse fluid, a very small solenoid with minimal current draw can operate the assembly. This small solenoid controls the substantial flow of rinse fluid past the assembly and ultimately from rinse valve  10  with minimal contact between the armature and the rinse fluid. 
         [0030]    In a preferred embodiment, the pressure tube  54  may be made of Delrin® AF which contains polytetrafluoroethylene (Teflon®) to eliminate the need for lubrication between the armature  60  and the interior of the pressure tube  54 . The use of Delrin® AF or another lubricious material or coating contributes to the improved reliability and efficiency of this valve because it substantially eliminates galling and flaking contamination. Additionally, this placement of the armature out of the primary flow path of the vast majority of the rinse fluid moving through the valve block increases the reliability and efficiency of the valve because the armature is not subject to the detrimental deposit buildup seen in typical rinse valve designs in which rinse fluid is in contact with a substantial portion of the armature as the valve is operated. 
         [0031]    As shown in  FIGS. 4A-B , the solenoid/poppet fixture  14  includes a poppet assembly  70  positioned opposite surface  64  of armature  60  and intersecting the primary flow path  200 . Poppet assembly  70  comprises a poppet member  90  on the top, which rests within a cavity  77  within a resilient diaphragm  72 . The diaphragm receives a rigid annular retainer  100  in an annular recess  79  in its bottom surface. A sealing ring  104  is positioned on a washer  106 , which in turn rests on guide member  82 , and abuts the bottom surface  105  of the annular retainer  100 . Finally, guide member  82 , which supports the sealing ring, is mounted for longitudinal movement in a circular cavity  18  in the valve block  17 . The diaphragm, annular retainer, sealing ring, washer and guide have corresponding apertures for receiving a stem  92  which extends downwardly from the poppet member  90 . The combination of the poppet member  90 , diaphragm  72 , retainer  100 , sealing ring  104 , washer  106  and guide  82  is held together by the mating of threads (not shown) inside of the guide aperture  86  with threads (not shown) on the stem  92 . 
         [0032]    Poppet member  90  has a circular platform  91  and a centrally located aperture  93 . The platform also has a raised annular inner seat  94  and a raised outer lip  95  encircling a central clearance area  96  in the platform. Poppet member  90  also includes a longitudinal bore extending from aperture  93  through stem  92  defining a poppet channel  98 . In a preferred embodiment, poppet member  90  is made of an engineered polymer, although the invention is not limited to the use of this material. 
         [0033]    Diaphragm  72  is made of a resilient material. Material such as NBR/Poly Fabric or any other suitable resilient material may be used. The diaphragm includes a central aperture  74 , a raised open ring portion  76 , and a rim  78 . The rim  78  has an annular recess  79  in its underside. In a preferred embodiment the diaphragm includes at least one pilot channel aperture  80  (as explained later) and includes at least one rim aperture  81  to aid in positioning and retaining the diaphragm in the block. 
         [0034]    Retainer  100  has a central aperture  102  and an annular upstanding wall  103 . Upstanding wall  103  is configured to nest within the annular cavity  79  in the underside of the diaphragm. The retainer  100  may be made of a rigid material. 
         [0035]    Sealing ring  104  may be made from a resilient material. Such resilient material may include any rubber-type material. The sealing ring has a central aperture  107 . 
         [0036]    Finally, the assembly includes guide  82  having a top surface  84 , and a bottom surface  85  which rests within a cavity  18  in the valve block  17 . A guide aperture  86  is formed in the guide and extends the length of the guide. The guide is configured to move longitudinally within cavity  18  of the valve block. In the illustrated preferred embodiment, the guide has four arms  88  extending radially outwardly from the guide aperture  86  along the length of the guide. These arms  88  define passageways  83  in the cavity  18  for the rinse fluid to flow past the guide  82 . 
         [0037]    As illustrated in  FIG. 2 , vacuum breaker outlet assembly  16  includes a sleeve valve  124  mounted in a sleeve valve cavity  126  adjacent to a second channel  208  leading from the poppet assembly  70 . The sleeve valve  124  comprises a sleeve  125  and a sleeve supporting member  128 . Sleeve  125  is supported within sleeve valve cavity  126  by a supporting sleeve member  128  mounted above the sleeve valve cavity. Supporting sleeve valve member  128  has a vent opening  130  in communication with the atmosphere outside of the rinse valve. Sleeve valve cavity  126  is in fluid communication with the vent  130 , as shown, for example in  FIG. 2 . 
         [0038]    Supporting sleeve member  128  has a cylindrical cavity for slidably receiving the sleeve  125 . As can best be seen in  FIG. 7 , sleeve  125  has an upper cylindrical portion  132 , a lower cylindrical portion  134 , and a partition  136  for blocking fluid flow between the cylinders. The peripheral walls of the cylinders have a plurality of ports  140 ,  142  extending through the walls. Also, an annular ledge  137  encircles the partition and extends outwardly from the cylindrical portions. An “O” ring  138  is positioned about the upper cylindrical portion  132  on top of the ledge  137  and an “O” ring  139  is positioned about the lower cylindrical portion  134  below the ledge  137 . 
         [0039]    When there is no incoming rinse fluid pressure, sleeve  125  is biased by spring  146  in the position illustrated in  FIG. 3 . In this position the sleeve valve is open so that air may flow from vent opening  130  past wall port  142  to the sleeve valve cavity  126 . As shown in  FIG. 5 , when the rinse fluid pressure in second channel  208  exceeds a predetermined threshold value, sleeve  125  will slide up into supporting sleeve member  128  against the bias of spring  146 , closing the sleeve valve  124  by way of the sealing engagement of “O” ring  138  against the bottom edge  144  of supporting sleeve member  128  so that the rinse fluid passes through the sleeve valve cavity  126  to the toilet bowl. Finally, it should be noted that sleeve valve  124  may be replaced by other valve types that function comparably such as a float valve. 
         [0040]    Valve block  17  includes a primary rinse fluid flow path  200  ( FIG. 5 ) and a secondary rinse fluid flow path  300  ( FIG. 3 ). The primary flow path  200  extends from the inlet fitting  20  to the outlet  212  ( FIG. 8 ) leading to the toilet and is the flow path over which the vast majority of the rinse fluid will flow through the rinse valve to the toilet. The primary flow path  200  passes through conduit  21  defined by inlet fitting  20 , a first channel  204 , main chamber  110 , guide passageways  83 , a second channel  208  and a third channel  210  ( FIG. 8 ) which flows through to the outlet  212 . 
         [0041]    As illustrated by  FIG. 5 , the first channel  204  is formed in the valve block  17  and extends from the inlet fitting  20  to the main chamber  110 . The guide passageways  83  are defined by the guide arms  88  and the cavity  18  in valve block  17  and extend the length of the guide  82 . The second channel  208  is formed in the valve block  17  and extends from the end of the guide passageway  83  to the vacuum breaker outlet assembly  16 . The third channel  210  is formed in the valve block  17  and extends through the lower cylindrical portion  134  of the sleeve  125  of the vacuum breaker outlet assembly  16  to the outlet  212  ( FIG. 8 ). 
         [0042]    Turning now to  FIG. 3 , the secondary flow path  300  moves through a pilot channel  302  to pilot chamber  108 . The pilot channel  302  branches off of the first channel  204  providing a narrow flow path from the first channel  204 , through the pilot channel aperture  80  in the diaphragm, to the pilot chamber  108 . 
         [0043]    In operation, initially the sleeve valve  24  of the inlet venting assembly  12  is in the position illustrated in  FIG. 2 . Ambient air entering the vent  30  is in fluid communication via the sleeve valve  24  with conduit  21  of inlet fitting  20 . When rinse fluid first enters the inlet cavity  18 , the pressure of the oncoming rinse fluid against the partition  36  ( FIG. 7 ) causes the sleeve  25  to slide up into the supporting sleeve member  28  thereby moving the sleeve valve  24  to the closed position seen in  FIG. 3 . “O” ring  38  is pushed against the bottom edge  44  of the supporting sleeve member  28  sealing the sleeve valve cavity  26  from receiving ambient air and allowing rinse fluid to fill the sleeve valve cavity  26 . 
         [0044]    As seen in  FIG. 3 , the rinse fluid also flows through the first channel  204  filling the main chamber  110  and flowing into the secondary flow path  300  filling the pilot chamber  108 . The rinse valve remains in this inactive state with the main chamber and the pilot chamber substantially filled and the sleeve valve  24  closed until a user flushes the toilet or the rinse valve is drained during servicing. 
         [0045]    As shown in  FIG. 4 , when the rinse valve is in the inactive state the armature  60  engages the raised inner seat  94  of the poppet member  90  in a closed position. The spring  62  ( FIG. 2 ) urges the armature against the inner seat  94 . The dimensions and shape of the inner seat  94  ( FIG. 4 ) provide a small sealing surface for the armature  60  and thus result in a higher applied sealing pressure and more efficient seal than if the sealing surface had instead been the entire surface of the poppet  90 . When the armature  60  is in the closed position shown in  FIG. 4 , rinse fluid in the pilot chamber  108  is blocked by the armature from draining through the poppet channel  98 . 
         [0046]    The rinse fluid in pilot chamber  108  exerts downward pressure against the poppet member  90 . The central clearance area  96  is dimensioned to be a larger surface area than the bottom surface of the retainer  100  against which rinse fluid in the main chamber  110  exerts an upward pressure. Because of the larger area of the central clearance area  96 , the rinse fluid in the pilot chamber  108  exerts a greater downward force on the upper surface of the poppet assembly  70  than the upward force exerted on the backside of the poppet assembly  70  by the rinse fluid in the main chamber  110 . This downward pressure helps to keep the poppet assembly  70  in the closed position so that less force is required by the armature spring  62  ( FIG. 2 ) to hold the poppet assembly closed with the sealing ring  104  engaged against the valve block  17 . 
         [0047]    When a user actuates the flush switch, a signal is sent to the solenoid  52  ( FIG. 6 ). The solenoid is energized in response to the signal and the armature  60  is drawn upward overcoming the force of the spring  62  and moving upwardly in the pressure tube  54  away from the entrance to the poppet channel  98  as shown in  FIG. 6 . Rinse fluid present in the pilot chamber  108  drains through the poppet channel  98  to the second channel  208  ( FIG. 6 ) thereby reducing the fluid pressure exerted on the upper side of the poppet assembly  70 . The force exerted by the rinse fluid on the backside of the poppet assembly  70  is now greater than the force exerted on the upper side of poppet assembly  70  thus enabling the force on the backside to move the poppet assembly  70  upward to the open position illustrated in  FIG. 5 . When the poppet assembly  70  moves upward, the sealing ring  104  is lifted off of the valve block  17  and the guide  82  is moved upward so that rinse fluid from the first channel  204  and the main chamber  110  flows into the guide passageway  83  to the second channel  208 . From there, rinse fluid flows to the vacuum breaker outlet assembly  16 . 
         [0048]    When the pressure exerted by the entering rinse fluid on the partition  136  of vacuum breaker outlet assembly  16  exceeds a predetermined threshold value, sleeve  125  will slide up into supporting sleeve member  128 , closing the sleeve valve  124  by way of the sealing engagement of “O” ring  138  against the bottom  144  of supporting sleeve member  128  and permitting the rinse fluid to pass from the second channel  208  through the sleeve valve cavity  126  and third channel  210  to the outlet  212  (as illustrated in  FIGS. 5 and 8 ) where appropriate piping is provided to transport the rinse fluid to the toilet. As long as the armature  60  remains open, the rinse fluid flows along the primary flow path  200 . 
         [0049]    As can be seen in  FIG. 5 , the armature  60  is disposed out of the primary flow path  200  of the rinse fluid. As noted earlier, typical prior designs dispose armatures directly in the primary flow path of the rinse fluid; the passage of rinse fluid combined with draining of the armature during servicing creates surface mineral deposit build-up on the armature and the internal surfaces of the housing surrounding the armature. Over time this build-up causes the armature to malfunction, first, by slowing the movement of the armature and, ultimately, by causing the armature to become seized in an open or closed position. A rinse valve with an armature seized in the closed position will not provide rinse fluid to a waste receptacle, and an armature seized in an open position will cause flooding of the waste receptacle. Locating the armature out of the primary flow path dramatically reduces the likelihood that the armature and its housing will develop detrimental surface mineral deposits; this design increases the reliability and longevity of the valve. 
         [0050]    An armature stop  61  comprising a metal conical shell  63  encircling a flat, elastomer or rubber-type pad  65  is positioned at the top of the pressure tube  54 . The metal conical shell  63  creates a stronger magnetic force on the armature for a given amount of current than would otherwise be present. When the solenoid is energized when a flush signal is applied, the armature moves to the open position seating against the pad  65 . When a flush signal is no longer received by the solenoid, the solenoid is no longer actuated and the armature  60  slides downwardly aided by the force of the spring  62 . Use of the rubber-type pad  65  in the armature stop  61  provides a rebound effect that ensures that the armature will not remain in the open position due to residual magnetism present in the armature stop  61 . 
         [0051]    The downward moving armature  60  pushes the poppet assembly  70  downward to a point where the flow of rinse fluid through the guide passageways  83  is reduced and rinse fluid begins flowing again to the secondary flow path  300 . However, because the armature  60  is covering the opening to the poppet channel  98 , rinse fluid cannot enter the poppet channel  98 . This blockage causes the rinse fluid to build up in the pilot chamber  108  and results in pressure from the rinse fluid in the pilot chamber  108  being exerted on the upper surface of the poppet assembly  70 . This pressure on the upper surface builds up until it exerts a greater downward force on the poppet assembly  70  than the upward force exerted on the backside of the poppet assembly  70  by the rinse fluid in the main chamber  110 . This force differential assists in moving the poppet assembly further downward into the closed position illustrated in  FIG. 3  with the sealing ring  104  engaged against the valve block  17 . Rinse fluid stops flowing to the second channel  208  and to the vacuum breaker outlet assembly  16 . 
         [0052]    Once rinse fluid stops flowing to the vacuum breaker outlet assembly  16  ( FIG. 4 ), rinse fluid pressure no longer holds the sleeve valve  124  closed and the sleeve  125  slides downward until the “O” ring  139  engages and seals against the valve block  17 . The flow of rinse fluid is shut off to the outlet  212  and fluid communication of air between the vent  130  and the outlet  212  is re-established through the sleeve valve  124 . In the event of a blockage severe enough to cause waste receptacle fluid to rise to the waste receptacle nozzles and flow backward into the vacuum breaker outlet assembly  16 , the backward flow of the waste receptacle fluid may fill the sleeve valve cavity  126  but will not be able to enter the rinse valve through the vacuum breaker outlet assembly  16  because the downward pressure exerted by the contaminated fluid on the sleeve  125  will keep the sleeve  125  down and sealed by the “O” ring  139  thereby stopping contaminated fluid from flowing through the valve  10  and into the potable or gray water system. 
         [0053]    While rinse fluid is not drained from the valve  10  after each time the actuator is actuated (after each flush by a user), it may be drained when the plane is serviced. During draining of the valve, the flow of rinse fluid into the inlet fitting  20  is stopped and rinse fluid drains out of the valve  10 . The armature  60  is closed during such draining. 
         [0054]    As the rinse fluid drains out of the valve  10 , the pressure on the partition  36  of the inlet venting assembly  12  is reduced and the sleeve  25  slides downward to the position illustrated in  FIG. 2  where the sleeve  25  is supported by the spring  46 . Ambient air from the vent  30  is in fluid communication with inlet fitting  20  through the sleeve valve  24 . This venting prevents a vacuum from forming in the valve  10  while the rinse fluid drains. 
         [0055]    The present invention includes design features that provide protection against damage caused by the freezing of rinse fluid inside of the valve. As illustrated in  FIG. 9 , the sleeve valve  24  is mounted between the expansion chamber  27  and the sleeve valve cavity  26 . A spring  47  is positioned between the sleeve supporting member  28  and the rim  29  of the expansion chamber  27 . In the inactive state before flushing or draining ( FIG. 3 ), the sleeve valve  24  is disposed in an upward closed position with rinse fluid present in the sleeve valve cavity  26 , the first channel  204 , the main chamber  110 , the secondary flow path  300  and the pilot chamber  108 . If the aqueous rinse fluid freezes, it will expand and exert force on the internal cavities of the rinse valve. 
         [0056]      FIG. 9  illustrates the rinse valve  10  when the force of the expanding rinse fluid has pushed the sleeve  25  and the sleeve supporting member  28  upwards against the force of the spring  47  into the expansion chamber  27 . This upward movement of the sleeve  25  and the sleeve supporting member  28  accommodates the expanding area required by the freezing fluid by decreasing the size of the expansion chamber and, thus, increasing the volume available in the sleeve valve cavity  26 . The features of the inlet venting assembly  12  described above provide substantial protection against damage caused by rinse fluid freezing in the rinse valve  10 . 
         [0057]    All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0058]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0059]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.