Patent Publication Number: US-2012042855-A1

Title: Ultra low power marine fuel poslishing system

Description:
CROSS REFERENCE TO RELATED CASES 
     This application is a continuation of International Patent Application No. PCT/US2009/033041, which claims the benefit of U.S. Provisional Application Ser. No. 61/025,980 filed Feb. 4, 2008, which is herein incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates, in general, to marine fuel polishing systems, and in particular to a piezoelectric pump utilized to circulate fuel through a fuel polishing system under low power conditions. 
     BACKGROUND 
     Often boats sit idle for long periods of time which can result in contamination of the fuel in the fuel tank and fuel lines. Diesel fuel can easily become contaminated with microorganisms such as bacteria, fungi, yeast, mold, and algae. Diesel fuel in the presence of water and nutrients makes conditions ripe for high bacterial growth. Water and microbes can be introduced from the outside air, from the filling station, or most commonly, from changes in storage temperatures, which causes condensation to occur within the tank. Water allowed to remain in fuel will culture a microorganism or bacteria that feeds on the hydrocarbons in the fuel, therefore degrading the fuel quality. Water can also allow algae to grow in the tank, typically adhering to the wall of the tanks. When the boat is operated and the fuel begins moving around—the contamination tends to break away from the wall of the tank and enters the fuel. This contamination can clog fuel filters and even shut down the engines. Accordingly, water is the worst and most common form of fuel contamination. 
     In order to combat water contamination, prior art fuel polishing systems have been developed to filter the fuel even when the engine is not running. These prior art systems utilize an independent fuel pump that continuously pulls fuel from the tank, through the filter, and back to the tank. However, these systems utilize traditional pumping technology that requires that the boat is hooked up to power at a dock due to the high power consumption of the pumps. Power may not always be available at the dock and is not available if the boat is on moorings. 
     SUMMARY 
     At least one embodiment of the invention provides a fuel polishing system comprising: a fuel tank having a fuel supply line and a fuel return line; a fuel filter attached to the fuel supply line; a piezoelectric pump selectively controlled to pump fuel from the fuel tank and through the filter and return the fuel to the fuel tank by directing the fuel to the fuel return line. 
     At least one embodiment of the invention provides A fuel polishing system comprising: a fuel tank having a fuel supply line for supplying fuel to a diesel engine and a fuel return line for returning fuel from the diesel engine to the fuel tank; a fuel filter attached to the fuel supply line; a fuel polishing module attached to the fuel supply line, the fuel polishing module comprising a piezoelectric pump adapted to pump fuel from the fuel tank and through the filter and return the fuel to the fuel tank by directing the fuel to the fuel return line, the fuel polishing module including a by-pass line to direct fuel around the piezoelectric pump when the diesel engine is in operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of this invention will now be described in further detail with reference to the accompanying drawing, in which: 
         FIG. 1  is a schematic view of a first embodiment of the ultra low power fuel polishing system in accordance with the present invention; 
         FIG. 2  is a schematic view of a second embodiment of the ultra low power fuel polishing system in accordance with the present invention. 
         FIG. 3  is a schematic view of a the fuel polishing module used with the ultra low power fuel polishing system of  FIG. 2 ; and 
         FIG. 4  is a schematic view of a solar power source and timer switch used with the fuel polishing module; and 
         FIG. 5  is a schematic view of a solar power source and sealed switch used with the fuel polishing module. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     A dedicated low power fuel polishing system  10  is shown in  FIG. 1 . The system  10  comprises a fuel tank  20  which is separately fluidly connected to a diesel engine  30  by a fuel supply line  40  and a fuel return line  50 . The fuel tank  20  is also fluidly connected by a dedicated fuel polishing supply line  42  and a dedicated fuel return line  52 . A fuel filter  60  is attached to the fuel polishing supply line  42  such that fuel coming from the fuel tank  20  is filtered. A fuel polishing module  70  is attached to an outlet of the fuel filter  60  and is controlled by a remote pump controller/timer  80  (shown housed within the fuel polishing module). The fuel polishing module  70  is attached to a power source  15 , typically a battery. The fuel polishing module  70  also includes an ultra low power pump such as a piezoelectric fluid pump. As directed by the controller  80 , the piezoelectric pump of the fuel polishing module  70  can continuously pull fuel from the fuel tank  20 , through the fuel filter  60 , and back to the fuel tank  20 . 
     An inline low power fuel polishing system  10 ′ is shown in  FIG. 2 . The system  10 ′ comprises a fuel tank  20  fluidly connected to a diesel engine  30  by a fuel supply line  40  and a fuel return line  50 . A fuel filter  60  is attached to the fuel supply line  40  such that fuel coming from the fuel tank  20  is filtered. A fuel polishing module  70  is attached to an outlet of the fuel filter  60  and is controlled by a remote pump controller/timer  80 . As directed by the controller  80 , the piezoelectric pump of the fuel polishing module  70  can continuously pull fuel from the fuel tank  20 , through the fuel filter  60 , and back to the fuel tank  20  through diverter line  54  and fuel return line  50 . The fuel polishing module  70  is attached to a power source  15 , typically a battery. 
     The fuel polishing module  70  is shown schematically in  FIG. 3  and includes a fuel inlet  72 , an engine fuel outlet  74 , and a fuel tank return outlet  76  for the fuel diverter line. The fuel polishing module  70  also comprises an ultra low power pump  90  in the form of a piezoelectric pump. When the engine  30  is not operating, the pump  90  is turned on by the controller  80  and pulls fuel from the fuel tank  20  through the filter  60  and into the fuel inlet  72 . The fuel is pumped back to the fuel tank  20  through the fuel tank return outlet  76 . When the engine  30  is operating, the fuel polishing module automatically switches to by-pass mode. The pump  90  is turned off and the fuel travels through the fuel by-pass line  78  around the pump  90  and exits module  70  through the engine fuel outlet. Check valve  92  is positioned in the diverted fuel line before outlet  76  and check valve  94  is positioned in the by-pass line  78  to ensure proper fuel flow within the fuel polishing module  70  and system  10 ′. 
     The piezoelectric pump  90  requires only minimal power for operation in comparison to pumps utilized in prior art fuel polishing systems. Accordingly, the system  10  of the present invention can operate on the boat&#39;s battery, or a supplemental battery. At least one system has been developed to pump about 50 gallons per day and operate on less than one Watt (less than two Amp-hours per day). Another system has been developed to pump about 100 gallons per day and operate on less than two Watts (less than three Amp-hours per day). This power consumption represents less than five percent of the capacity of a standard Group 27 battery. Battery operation allows the system to run even when no shore power is available or when the boat is moored. A suitable pump can be made utilizing RLP™ piezoelectric disk from the AdaptivEnergy LLC. Another alternative is utilizing the VIVA™ piezoelectric pump from Parker Hannifin Corporation. 
     As an alternative, the pump  90  may be powered for continuous operation by solar power. Referring now to  FIGS. 4 and 5 , the fuel polishing module  70  is shown connected to a solar panel  15 ′. A timer switch  98  or sealed switch  98 ′ is shown in  FIG. 4  and  FIG. 5 , respectively. The solar panel  15 ′ can be used to charge a battery so that the pump  90  may be set for continuous 24 hour operation or for operation at any time the diesel engine  30  is not in operation. 
     Accordingly, the system  10  enables unattended fuel recirculation/polishing ensuring that the fuel does not go bad after periods of sitting idle. The pump controller/timer  80  allows the operator to set how long the system  10  is active or it can be set for continuous use. At 50-100 gallons/day, the slow flow/long duration polishing maximizes the water separation effectiveness of the fuel filters. 
     The system  10 ′ is designed to retro fit into an existing fuel circuit. In one embodiment a parallel system is provided just for polishing with lower micron filtration. 
     Another advantage is that no manual valve is needed to switch from normal operation to polishing mode as the fuel polishing module  70  has an internal automatic diverter. 
     While the system  10  has been shown as particularly useful in marine applications, the invention is not limited as such, and may also be useful in other applications where diesel fuel contamination is a problem. 
     Although the principles, embodiments and operation of the present invention have been described in detail herein, this is not to be construed as being limited to the particular illustrative forms disclosed. They will thus become apparent to those skilled in the art that various modifications of the embodiments herein can be made without departing from the spirit or scope of the invention.