Abstract:
A shut off valve ( 10 ) is provided for use in an aiarcraft lavatory system ( 70 ) during maintenance sanitizing operations. The shut off valve includes an inlet passage ( 20  ) in intermittent fluid communication with an outlet passage ( 30 ) and a magnetic flapper body ( 40 ) movable between a rest position and a seal position between said inlet passage and said outlet passage. The flapper body is moved by a magnetic actuator ( 60 ) whereby upon placing said magnetic actuator within the proximity of the flapper body, the flapper body is moved form the rest position and, with the assistance of fluid flow within the valve, into the seal position, thus preventing fluid communication between the inlet passage and the outlet passage.

Description:
FILE OF THE INVENTION  
       [0001]     This invention relates generally to fluid shut off valves and more specifically to an automatic shut off valve using magnetic actuation.  
       BACKGROUND OF THE INVENTION  
       [0002]     The modern aircraft lavatory uses the flow of disinfectant fluid or a powerful pump to remove waste from a toilet into a waste holding tank. During ground maintenance the waste tank is emptied and sanitized. Sanitation is especially important to kill any infectious disease agents potentially carried in human waste. The emptying and sanitizing processes are typically performed by airport ground crews using a lavatory cart. The cart includes a supply of disinfectant fluid as well as a disposal tank. Disinfectant fluid is pumped into the aircraft waste holding tank after waste from the flight is drained.  
         [0003]     In order to do an effective job of sanitizing the aircraft waste storage tank, it is desirable to fill the waste storage tank up to a specific level. Filling to a high level has many potential drawbacks if overfilling occurs. Overfilling can create spillage of disinfectant fluid, potentially contaminated with human waste. Spilled disinfectant fluid can freeze at high altitudes, creating solid projectiles, sometimes referred to as blue ice, which are potentially dangerous to the aircraft, especially its engines. Disinfectant fluid is harmful to the aircraft structure and electronics. Disinfectant fluid also includes a strong smelling detergent which when spilled on the interior of the aircraft via overfilling the toilet is objectionable, thus, it is desirable to minimize spills.  
         [0004]     A valve which can automatically prevent overfilling of the waste holding tank is desired. An additional desire is to provide a valve with automatic shut off for use during the filling operation in combination with a backflow prevention device for use during normal operations.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention is directed to an automatic shut off valve and to an aircraft lavatory system which may be sanitized while avoiding any overfilling of the sanitary waste holding tank.  
         [0006]     In one embodiment the invention provides a shut off valve for regulating fluid flow which includes an inlet passage in intermittent fluid communication with an outlet passage, a magnetic flapper body movable between a rest position and a seal position between the inlet passage and the outlet passage and a magnetic actuator that moves the flapper body toward a seal position, thus, preventing fluid communication between the inlet passage and the outlet passage.  
         [0007]     In another embodiment the invention provides a lavatory system for use on an airplane which includes one or more toilets, each toilet including a drain passage for disposal of sanitary wastes. The system also includes a waste tank attached to the drain passages from said toilets, a shut off valve for regulating flow of disinfectant fluid used to rinse the waste tank, a vertically canted tube in fluid communication with the waste tank, and a magnetic float within the tube whereby the float rises and falls in response to level changes within the waste tank. The shut off valve includes an inlet passage in intermittent fluid communication with an outlet passage, which directs fluid to the waste tank. The valve also includes a magnetic flapper body movable between a rest position and a seal position between the inlet passage and the outlet passage. When a predetermined level is reached in the waste tank, the magnetic float comes within the proximity of the magnetic flapper body, and the flapper body is moved from a rest position and, with the assistance of fluid flow pressure into a seal position.  
         [0008]     The present invention provides numerous advantages not realized in the prior art. First, the invention provides a no-spill filling system, thus, avoiding potential freezing of spilled fluid and avoiding the problems associated with a spilled, highly aromatic and corrosive fluid. The invention also provides a shut off valve which may be actuated magnetically, avoiding the need for a mechanical actuator. As a result, the valve may be constructed with fewer parts and seals which minimizes potential failures. Additionally, the shut off valve within the system functions automatically thereby eliminating the need for airline ground crews to consistently check the level of disinfectant fluid being fed into the waste tank during sanitizing operations. Thus, the valve serves as a backup if the ground crew forgets to shut off the inlet supply at the appropriate level from the truck.  
         [0009]     These and other features, aspects and advantages of the present invention will be fully described by the following description, appended claims, and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0010]      FIG. 1  is a cutaway view of the shut off valve;  
         [0011]      FIG. 2  is a schematic of the layout of an aircraft lavatory;  
         [0012]      FIG. 3  is a perspective view of an aircraft and lavatory cart; and  
         [0013]      FIG. 4  is a perspective view of a waste tank. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     Referring to  FIG. 1 a  shut off valve  10  is shown for use in an aircraft lavatory system. The shut off valve  10 , as described in more detail below, functions to prevent overfilling of a waste tank with disinfectant fluid.  
         [0015]     The shut off valve  10  includes a valve body  12 . The valve body  12  may be made from non-magnetic, non-corrosive materials having characteristics of high strength. The shut off valve  10  includes an inlet passage  20  through which disinfectant fluid enters the shut off valve  10  and an outlet passage  30  through which disinfectant fluid exits the shut off valve  10 . The shut off valve includes a flapper body  40  situated within the inlet passage  20  which regulates the intermittent fluid communication between the inlet passage  20  and the outlet passage  30 . When the flapper body  40  is in a rest position, fluid may pass from the inlet passage  20  into the outlet passage  30 . When the flapper body  40  is in a seal position, fluid is prevented from passing from the inlet passage  20  into the outlet passage  30 .  
         [0016]     The flapper body  40  is a magnetic piece which has the ability to block the outlet passage  30 . The flapper body  40  may be manufactured from a magnetic material or may be manufactured from a non-magnetic material and have one or more magnets  42  attached to its surface. The flapper body is hinged at one end to the shut off valve body  12  allowing the flapper body  40  to rotate from a rest position to a seal position. The seal position has the flapper body  40  covering the outlet passage  30 . The rest position has the flapper body  40  resting upon the valve body  12 . The valve body  12  may be manufactured with a cavity  14  which provides a place for the flapper body  40  to rest. The size and shape of the cavity are designed based on numerous factors including the flowrate of fluid through the valve  10 , the density of the fluid, the flapper body  40  shape, the weight of the flapper body  40 , and length and orientation of the inlet passage  20 . When the flapper body  40  is within the cavity  14  the flow of fluid in the inlet passage  20  is not disturbed.  
         [0017]     The shut off valve  10  may also include a check valve  50 . The check valve  50  functions to prevent back flow of any fluid, namely human waste within the waste tank during normal, non-sanitizing operations. These materials can hinder the function of the flapper body  40 . The check valve  50  may be situated within or adjacent to either the inlet passage  20  or the outlet passage  30 . The check valve  50  may be any type known in the art-including ball check and flapper check types. The check valve  50  may be manufactured as part of the valve body  12  or alternatively may be a fitting which is able to attach to the valve body  12 .  
         [0018]     The shut off valve  10  includes a magnetic actuator  60 . The magnetic actuator  60  functions to move the flapper body  40  from its rest position. Movement occurs when the magnetic actuator  60  is brought into close proximity to the flapper body  40 . Magnetic forces between the magnetic actuator  60  and the flapper body  40  cause movement of the flapper body  40 . In one embodiment of the invention repelling magnetic forces are used. In another embodiment (not illustrated) the flapper body  40  is situated on a fulcrum and attractive magnetic forces are used to move one end of the flapper body towards the magnetic actuator  60  while the other end rotates to seal the outlet passage  30 . In one embodiment of the invention, the magnetic actuator  60  is a float. Rising and falling fluid levels move the magnetic actuator  60  into and out of proximity of the flapper body  40 . In another embodiment of the invention the actuator  60  is not magnetic, but is a float which triggers a stationary electromagnet at a set level. The electromagnet then actuates the flapper body  40 . There is no requirement for the magnetic actuator  60  to ever be in contact with the flapper body  40 . Thus, the valve body  12  may be a sealed unit and as the magnetic actuator  60  approaches the outside of the valve body  12 , the flapper body  40  is moved.  
         [0019]     The valve body  12  may also include a reset magnet  44 . The reset magnet  44  helps move or keep the flapper body  40  in a rest position when sealing of the outlet passage  30  is not desired. The reset magnet  44  generates a magnetic force which repels the flapper body  40  or magnets  42  thereupon. The reset magnet  44 , due to its position or inherent magnetic force does not create a force which exceeds the force generated by a magnetic actuator  60  and the pressure of flow through the inlet passage  20 . Thus, when the magnetic actuator  60  is in a proximal position, the force it generates can overcome the force generated by the reset magnet  44  and the flapper body  40  may be moved towards a seal position with the aid of the pressure of flow through the inlet passage  20 . The valve body  12  may also be manufactured with a bypass passage  16 . The bypass passage  16  directs a small amount of fluid through a different portion of the valve body  12  to provide rinsing of the float  60 . The bypass passage flow rate depends on the backpressure created in the system when disinfectant fluid is being added to the waste tank.  
         [0020]     The shut off valve  10  may be used as part of a lavatory system  70  on an airplane as shown in  FIG. 2 . The system  70  includes one or more toilet bowls  74 , a waste tank  80 , a drain passage  82  for the waste tank  80 , and a pump  86 . The exterior wall of an aircraft  94  and connecting fixture  92  are shown as well in  FIG. 2 . Waste is deposited in the toilet  74  by aircraft passengers. Waste is flushed from the toilet  74  by disinfectant fluid pumped into the toilet  74  by pump  86  and into the waste tank  80 .  
         [0021]     At the end of a flight the waste tank  80  is sanitized. This process is typically performed by a ground crew using a lavatory cart  100  as shown in  FIG. 3 . Referring back to  FIG. 2 , waste is drained from the waste tank by opening the drain passage  82  valve. Waste is transferred to a holding tank on the lavatory cart  100 . The drain passage  82  is then closed and the waste tank  80  filled with disinfectant fluid. Disinfectant fluid is added from a holding tank on the lavatory cart  100  to the waste tank  80  through the shut off valve  10 . As the level of disinfectant fluid is rising within the waste tank  80 , the magnetic actuator  60  is brought into proximity of the valve body  12  to close off the flow of disinfectant fluid as shown in  FIG. 4 . The automatic shut off provided by the magnetic actuator allows the ground crew to perform other tasks while the waste tank is being filled, without risking overfilling.  
         [0022]     The lavatory system  70  may also include a tube  90  to house the magnetic actuator  60 . The tube  90  is oriented alongside of the waste tank and liquid from the waste tank  80  can flow into the tube  90 . In an embodiment of the invention, the tube  90  is next to the waste tank  80  and is mounted in a vertically canted manner. The level of the fluid within the tube  90  is directly proportional to the level of fluid within the waste tank  80 . When the actuator is a float, the float moves in response to level changes in the fluid within the tube  90 . The tube includes one or more vents near its top to allow air to enter and be expelled in order to avoid vacuum or over pressure conditions when fluid levels in the waste tank change. As the fluid level in the tank  80  reaches the top of the tank  80 , the level of fluid in the tube causes the actuator  60  to get close enough to the shut off valve  10  to move the flapper body  40 . The flapper body  40  is then assisted into the seal position by the fluid flowing through the valve  10  and flow into the tank  80  is stopped.  
         [0023]     Additional advantages and modifications will readily appear to those skilled in the art. For example, different locations of the tube may be utilized. Different materials or composites may be used to form the shut off valve. Also, the shut off valve may be used in a vacuum transfer aircraft toilet system if disinfectant fluid is still used during service operations and there are ways where the disinfectant fluid can spill because of overfilling and cause problems. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.