Abstract:
A fuel water separator (FWS) filter that is configured to permit water to be drained from the water sump of the FWS filter without shutting off fuel flow to the FWS filter. A check valve is positioned between the water sump and the filter element. When the FWS filter is under vacuum (e.g. as in operation), the check valve can be closed to allow water to drain from the sump. The check valve can close automatically by floating on accumulated water in the sump until the water rises to a level where the check valve is closed. The check valve can also close by opening the drain valve of the FWS filter, which causes a differential pressure between the sump and the vacuum created in the filter element chamber, which forces the check valve to close.

Description:
FIELD 
     This disclosure relates generally to a fuel water separator (FWS) type filter that is configured to separate water from fuel being filtered, such as ultra-low sulfur diesel (ULSD) or biodiesel. In particular, this disclosure relates to a valve that is disposed between the water sump of the FWS filter and the filter element which allows water to be drained from the water sump during operation of the FWS filter without shutting off fuel flow. 
     BACKGROUND 
     In a typical FWS filter, when used under suction, the FWS cannot be drained of its water during operation. The vacuum that is created within the filter housing draws air through the drain valve, prohibiting the water from flowing out of the water sump of the FWS. To drain the water, current practices require shutting the engine down or diverting the fuel flow via manual valves to permit draining of the water. 
     A FWS filter that allows water to be drained from the water sump without shutting the engine down or diverting fuel flow (i.e. without shutting off fuel flow to the FWS filter) is desirable. 
     SUMMARY 
     This disclosure relates to a FWS filter that is configured to permit water to be drained from the water sump of the FWS filter without shutting off fuel flow to the FWS filter. Therefore, the filter can remain in operation while draining water from the sump. 
     The filter is preferably configured for use with fuel, such as ultra-low sulfur diesel (ULSD) or biodiesel. However, the concepts of the filter described herein could be employed with any type of filter which is used to separate water from a fluid, for example hydraulic fluid, oil or lubrication fluid, air, and the like, to permit the water to be drained from a sump while the filter remains in operation. 
     In the case of a FWS filter, a check valve is positioned between the water sump and the filter element. When the FWS filter is under vacuum (e.g. as in operation), the check valve can be closed to allow water to drain from the sump. The check valve can close automatically by floating on accumulated water in the sump until the water rises to a level where the check valve is closed. The check valve can also close by opening the drain valve of the FWS filter, which causes a differential pressure between the sump and the vacuum created in the filter element chamber, to cause the check valve to close. 
     One embodiment of a fuel water separator filter includes a filter housing defining a filter element chamber and a water sump, where the filter element chamber is separated from the water sump by a wall. A passageway is provided in the wall that fluidly connects the filter element chamber and the water sump. A valve controls flow through the fluid passageway, with the valve having a first, open position that permits fluid flow from the filter element chamber into the water sump and a second, closed position preventing fluid flow between the filter element chamber and the water sump. The filter housing further includes a drain valve in communication with the water sump to permit draining of water from the water sump. 
     The filter element that is disposed in the filter element chamber is configured to separate water from fuel. For example, the filter element can be a concentric filter within a filter configuration, with an outer stage filter that is configured to coalesce water from fuel, an inner stage filter that is surrounded by the outer stage filter, and a space between the outer stage filter and the inner stage filter. The inner stage filter is configured to separate coalesced water from the fuel and also remove fine solid contaminants from the fuel. The passageway in the wall is located at a position in communication with the space between the inner stage filter and the outer stage filter so that separated water flows down through the inner space and through the passageway and into the water sump. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of the FWS filter described herein. 
         FIG. 2  is a perspective view through a section of the water sump to show the check valve and the wall separating the water sump and the filter element chamber. 
         FIG. 3  is a partial cross-sectional view of the FWS filter focusing on the water sump. 
         FIG. 4  is a cross-sectional view of the FWS filter showing the flow of fuel and with the drain valve closed. 
         FIG. 5  is a cross-sectional view of the FWS filter when the drain valve is initially opened and the check valve being closed. 
         FIG. 6  is a cross-sectional view of the FWS filter with the drain valve opened showing draining of water from the water sump. 
         FIG. 7  is a cross-sectional view of the FWS filter showing the drain valve. 
     
    
    
     DETAILED DESCRIPTION 
     With reference initially to  FIG. 1 , an embodiment of a FWS filter  10  incorporating the water drain concepts described herein is illustrated. The FWS filter includes a filter housing  12  and a filter element  14 . In the illustrated embodiment, the FWS filter  10  is configured as a spin-on filter that is configured for detachable connection to a filter mounting head (not shown). As used herein, the term spin-on refers to the use of rotation to effect connection and disconnection of the filter to and from the head. 
     The filter  10  will be described herein as being configured for use with fuel, such as ultra-low sulfur diesel (ULSD) or biodiesel. However, the concepts of the filter described herein could be employed with any type of filter which is used to separate water from a fluid, for example hydraulic fluid, oil or lubrication fluid, air, and the like, to permit the water to be drained from a sump while the filter remains in operation. In addition, the filter will be described as being configured for outside-in flow of the fuel where the fuel flows generally radially inward through the filter media to a central space and then out through a central outlet. However, the concepts described herein can also be employed on a filter that is configured for inside-out flow of fuel where the fuel flows generally radially outwardly through the media during filtration. 
     As would be known to someone of ordinary skill in the art, the head includes an inlet for dirty fuel to be filtered by the filter  10 , and an outlet for filtered fluid that has been filtered by the filter. The housing  12  can be formed of materials known in the art, including plastic or metal. Returning to  FIG. 1 , the housing  12  includes a shell  16  that includes an end wall  18  defining a closed end of the shell, and a side wall  20  extending from the end wall. The side wall  20  has an end  22  opposite the end wall  18  that defines an open end of the shell. The end  22  of the side wall includes exterior threads  24  adjacent the open end that are configured to engage with threads on the head to connect the filter to the head. The head and housing  12  described so far are conventional in construction. Further information on spin-on type filter housings and heads can be found in U.S. Pat. Nos. 7,882,961 and 7,614,504, which are incorporated herein by reference in their entirety. 
     With reference to  FIG. 1 , the housing  12  defines a filter element chamber  26  and a water sump  28 . The filter element chamber is separated from the water sump by a wall  30  that is fixed to the side wall  20  parallel to the end wall  18 . 
     The filter element chamber  26  is sized to receive the filter element  14  therein. The filter element  14  that is disposed in the filter element chamber  26  is configured to separate water from fuel. For example, the filter element  14  can be a concentric filter within a filter configuration, with an outer stage filter  32  that is configured primarily to coalesce water from fuel and also configured to remove fine solid contaminants from the fuel, an inner stage filter  34  that is surrounded by the outer stage filter, and a space  36  between the outer stage filter and the inner stage filter. The inner stage filter is configured to separate coalesced water from the fuel and also remove fine solid contaminants from the fuel. Further information on a concentric filter within a filter configuration designed for fuel water separation that can be used for the filter element  14  is disclosed in U.S. Patent Application Publication No. 2011/0168621 which is incorporated herein by reference in its entirety. However, other types of filter elements including more than two stages or a single stage can be used. 
     With reference to  FIGS. 1-3 , the wall  30  separates the filter element chamber  26  from the water sump  28 . At least one passageway  40  is formed in the wall  30  that fluidly connects the filter element chamber and the water sump. The passageway  40  is the only passage through which water separated by the filter element  14  can flow into the sump  28 . The passageway  40  is located in the wall  30  at a radial position corresponding to the space  36  between the outer stage filter  32  and the inner stage filter  34 . Therefore, separated water can flow down through the space  36  and through the passageway  40  and into the water sump. 
     A check valve  50  is disposed in the water sump that controls flow through the passageway  40 . The valve has a first, open position (shown in  FIGS. 1-4 ) that permits fluid flow from the filter element chamber into the water sump and a second, closed position (shown in  FIGS. 5 and 6 ) preventing fluid flow between the filter element chamber and the water sump. The valve  50  can be any type and have any configuration that achieves these functions. For example, the valve could be constructed as a plate that closes one or more passageways  40  in the wall  30 . 
     The drawings illustrate a single passageway  40  in the wall  30 . However, a plurality of passageways  40  could be formed in the wall  30 . Each passageway  40  could be controlled by its own valve, or a single valve could control flow through all of the passageways  40 . 
     In one embodiment, the valve  50  comprises a ball  52  and a cage  54  disposed in the water sump, with the ball being disposed within the cage so that the cage guides the ball between the first position and the second position. As evident from  FIG. 3 , the wall  30  includes a first surface  60  that faces the water sump  28  and a second surface  62  that faces the filter element chamber  26 , and the cage  54  is fixed to the first surface. In the illustrated embodiment, the cage  54  comprises a plurality of posts extending downward from the first surface  60  to ends adjacent to the end wall  18 . The ball  52  is held between the posts with the ball being able to travel between an open position shown in  FIGS. 1-4  near the end wall and a closed position shown in  FIGS. 5-7  where the ball seats within the passageway  40  to close the passageway and prevent fluid flow therethrough. 
     The ball  52  is selected to have a density that allows it to float on the water that accumulates in the sump  28  but sink in fuel. Since the fluid accumulated in the sump is primarily water (i.e. there could be some trace amounts of fuel in the water in the sump), the ball floats on the water as the water accumulates, until enough water accumulates so that the floating ball closes off the passageway  40  by seating in the passageway. If a valve other than a ball is used, the valve is nonetheless selected so that it can float on the water that accumulates in the sump  28  so as to float upward to close the passageway. 
     With reference to  FIG. 7 , the end wall  18  includes a water drain valve  70  which, when opened, permits water to be drained from the water sump  28 . Any configuration of drain valve can be used as long as the drain valve can be actuated, manually or automatically, between a closed position preventing the draining of water from the sump and an open position allowing the draining of water. The configuration and operation of drain valves in FWS filters is known to those of ordinary skill in the art. In addition, as shown in  FIG. 3 , a sensor  72  is provided in the sump  28  that detects when enough water has accumulated to send a signal to an operator that the sump should be drained. 
     The operation of the FWS filter  10  will now be described with reference to  FIGS. 4-6 . Although not illustrated in the drawings, in use the FWS filter will be connected to a mounting head via the threads  24 . With reference initially to  FIG. 4 , fuel to be filtered that has entered the fuel inlet in the mounting head enters the chamber  26  between the outer stage filter  32  and the inner surface of the side wall  20  as shown by the arrow. The fuel then flows radially inward through the outer stage filter  32  into the space  36 . During this time, the outer stage filter  32  removes particulate matter from the fuel and coalesces water contained the fuel. The fuel then flows through the inner stage filter  34 . The coalesced water in the fuel is separated by the inner stage filter before entering the inner stage filter media, with the separated water then flowing downward in the space  36  toward the water sump. The inner stage filter also removes fine solid contaminants from the fuel as the fuel flows through the inner stage filter. The now filtered fuel flows into a central interior space of the filter element and flows up and out through a central outlet defined by an endplate of the filter element  14 . 
     The separated water that flows downward in the space  36  flows through the opening(s)  40  and into the sump  28 . As indicated in  FIG. 4 , with the drain valve  70  closed and the valve  50  open, a low pressure (i.e. vacuum) is defined within the central interior space as well as in the water sump, while the outside of the filter is subject to atmospheric pressure. As a result, the separated water can flow downward into the water sump  28  for collection. 
     Over a period of time of use of the filter, water continues to accumulate in the water sump.  FIG. 5  illustrates a state where enough water has accumulated to float the ball upward so that it seats in the passageway  40  to close the passageway. At about the same time, the sensor  72  sends a signal to the operator to drain the sump. When the drain valve  70  is opened, this exposes the water sump to atmospheric pressure while the central interior space of the filter element on the other side of the wall  30  (i.e. the filter element chamber side) remains at low pressure (i.e. vacuum). As a result, water can drain from the sump through the drain valve. At the same time, the low pressure in the filter element space compared to the pressure in the water sump keeps the ball sucked into the passageway  40  to hold the ball in place. 
       FIG. 6  illustrates the drain valve fully opened and water draining from the sump. Atmospheric pressure is present in the water sump while the central interior space remains at low pressure. The ball continues to be held in the closed position in the passageway due to the suction in the central interior space. At the same time, as is illustrated in  FIG. 6 , fuel to be filtered can continue to flow through the filter. As a result, the filter can remain in operation while draining water from the sump. During this period any water separated by the filter element  14  accumulates at the base of the filter element  14  on the top surface  62  of the wall  30  until the water is drained, the drain valve  70  is closed, and the valve  50  re-opens. 
     Alternatively, if the water level in the sump is not high enough for the ball to float onto the seat of the passageway, and the drain valve is opened while the engine is running, the vacuum created in the central interior space will suck the ball into the seat of the passageway  40  to close the passageway to permit water to drain from the sump. 
     Once the water is drained from the sump, the drain valve  70  is closed. Because there is not a perfect seal between the ball and the seat on the passageway  40 , the pressures in the filter element space and in the sump will equalize (i.e. the pressure in the sump will return back to low pressure), and the ball will move back down to its first, open position permitting water to again accumulate in the sump. 
     The invention may be embodied in other forms without departing from the spirit or novel characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.