Abstract:
A fuel vapor separator used in fuel delivery systems of a marine engine for recovery of fuel vapors and to prevent fuel spills when the engine is tilted.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention is related to a fuel vapor separator used in fuel delivery systems of a marine engine for recovery of fuel vapors and to prevent fuel spills when the engine is tilted. 
     2. Discussion 
     Small outboard marine engines are usually detachable and mounted to the transom of a boat. These engines typically include an integrated fuel system which draws liquid fuel under suction from a can or tank in the boat. The fuel is routed through a vapor separator unit to condense or recover vapors to be burned by the engine through the air intake system. The fuel in the vapor separator is delivered at high pressure to the fuel injection system. Larger inboard or inboard/outboard marine engines also typically include an integrated fuel system which draws fuel from under suction and is routed through a vapor separator unit to capture and combust the captured vapors by the engine to prevent fuel vapor build-up in enclosed areas of the boat. 
     The marine industry has long recognized that fuel vapors on boats are an issue, particularly in enclosed compartments. To prevent fuel spills, boat safety regulations have long required that fuel routed between a tank and engine be sucked under a vacuum instead of being provided at pressure, as is commonly performed in the automobile industry. Therefore, fuel is withdrawn from the tank at a negative pressure to prevent fuel spilling into the boat, should the fuel line rupture. However, at low pressures, fuel readily vaporizes, especially when combined with high temperatures near engines and jarring conditions as a boat passes over waves. Beyond capturing vapors to prevent emissions or to prevent the potential for uncontrolled combustion of vapors near an engine, if vapors are in the fuel provided to the engine, a condition known as vapor lock may occur. 
     Vapor separators are designed to address the above vapor issues. Some vapor separators allow heated fuel from the fuel rail of the fuel injectors to be returned and any vapors present in the fuel rail to be condensed back into a liquid before the fuel is reintroduced to the high pressure pump and provided to the fuel rail of the injector system. In some outboard motors, the vapors may be vented to the atmosphere by the vapor separator however in engines that are enclosed in compartments, the fuel vapor is provided to the engine fuel intake system through a vacuum line connection and combusted in a controlled manner within the engine. 
     Vapor separators include a vapor vent valve in most marine applications with a float actuated valve for automatically closing the vent line whenever the fuel level in the separator rises above a predetermined level. This float valve prevents liquid fluid from being provided into the air intake of the engine through the vacuum line designed to provide only fuel vapors to the engine. Additionally, the float mechanism is also designed to close the vent line, in particular for removable outboard motors, when the engine is tipped so that liquid fuel does not drain out of the vapor vent. 
     Prior art fuel vapor vent valve arrangements are commonly a buoyant float supported by the liquid fuel just below the vapor line connected to a needle valve which closes when the liquid fuel lifts the float. A typical prior art needle vent valve system  200  is depicted in  FIG. 1 . These needle valves  200  include floats  202  commonly carried on a pivot pin  204 , with the rotational axis of the float pivot being oriented parallel relative to the pivotal axis of the engine mounting bracket so that the float will close the vent passage  206  with a needle valve  208  whenever the engine is rotated to a tilt condition such as an in an outboard motor with the prop out of the water. Closing the passage when the engine is tilted prevents the liquid fuel from running through the vapor separator when the engine is shut off and tilted or prevents liquid fuel from running through the vapor portion of the vapor vent valve to the air intake of the engine while it is running. 
     Many outboard marine engines are often configured to be manually removed from the boat after the use and stored. When the engine is removed, users commonly lay the engine on its side to protect the prop and tiller arm when placing the engine on a trailer, in a vehicle cargo area, or perhaps on the bed of a pick-up truck. When the marine engine is laid on its side, the pivotal axis of the vent valve mechanism is no longer aligned with the engine and many times the float valve will not properly close the needle valve or the needle valve later becomes displaced during transit which may allow liquid fuel to leak through the vapor exit on the vapor separator to the engine, engine compartment, or area within the engine is stored. Accordingly, an improved fuel vapor separator in which the vent control device can accommodate engine tipping in non-conventional directions is desirable. It is also desirable to have a vapor separator that does not allow solid fuel to vent through the vapor outlet during engine operation due to vibrations or jarring, such as wavy conditions where the valve or float is moved, even though liquid fuel is present, thereby allowing liquid fuel to splash into the vapor outlet. Any splashing of liquid fuel into the vapor outlet causes, in systems where the vapor outlet is connected to the air intake allows liquid fuel to be provided to the air intake of the engine causing a condition of too much fuel, commonly resulting in stalling of the engine. Therefore, it is desirable to prevent instantaneous venting due to vibration and allow for control of when the vapor is vented through the vapor separator. 
     Vapor separators are not used in automotive applications because the factors which produce excessive vapors in marine applications are generally not present. Furthermore, vehicles have typically less concern regarding fuel vapor build-up in enclosed areas of the vehicle. Some automotive emission systems incorporate a “roll-over” vent valve into the fuel tank, however these are passive features in the emission system that simply protect the open vent line to a vapor collection canister. The automotive engine would continue to operate unaffected and without interruption if the roll-over vent valve was disabled or removed. In comparison, in marine systems where the vapor vent valve is an active component of the engine, any failure or malfunction potentially would disable the engine entirely. 
     SUMMARY OF THE INVENTION 
     In view of the above, the present invention comprises a fuel supply system for a marine engine. The fuel supply system includes a vapor separator having an enclosed interior chamber for collecting a volume of liquid fuel and fuel vapors. A suction pump transfers liquid fuel under negative pump pressure from a remote fuel tank to the interior chamber. A high pressure pump transfers liquid fuel under positive pressure from the interior chamber to a fuel injection system of the engine. This high pressure fuel pump is located close to the intake or injectors on the engine as typically regulations prevent pressurized fuel lines from being longer than eighteen inches on a marine vessel. The vapor separator includes a vent valve device communicating with the interior chamber for permitting the escape of fuel vapors trapped in the interior chamber. The vent valve device includes an enclosed top end permeated by an escape passage. A needle valve is disposed on a spring and is biased by the spring to operatively seal a vent passage. A magnetic coil may be attached to a relay and a thermistor circuit that senses when liquid fuel is present. When the thermistor senses that liquid fuel is not present it may switch a relay that provides power to the magnetic coil which opens the needle valve. The magnetic coil may further be controlled by a control module, such as the engine control module, which controls a relay to switch off and on the magnetic coil. 
     The system is designed to prevent the escaping of fuel, even when the engine power is off. For example, when power is off, such as when the engine is not running, the spring biases the needle valve to a closed position preventing escape of vapors and liquid fuel. When liquid fuel is sensed as being present, and power is being provided, such as when the engine is running or the ignition of a vehicle is turned on, the system causes the needle valve to remain closed as power is not provided to the coil. When no fuel is present, and power is on, power may be supplied to the coil, allowing the needle valve to open. To prevent opening of the needle valve due to vibrations or other temporary removal of fuel from contact with the thermistor, the thermistor circuit may be programmed with a delay such as a ½ second to one second, or more, before venting vapor by turning on the magnetic coil to open the needle valve, therefore preventing accidental discharge of fuel through the vapor vent from vibrations or waves. Furthermore, by being biased to the closed position, such as when the engine is off, prevents escape of fuel for when outboard motors are transported and the escape of vapors when the engine is off. 
     The fuel supply system according to the subject invention overcomes the short comings and disadvantages of the prior art by providing a unidirectional vent valve device for a vapor separator of a marine engine that also allows control of the timing of venting of fuel vapors from the vapor separator. 
     Further scope of applicability of the present invention will become apparent from the following detailed description, claims, and drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view of a prior art vent control device; 
         FIG. 2  is a side elevational view of a typical outboard marine engine; 
         FIG. 3  is a schematic diagram of a fuel delivery system for an outboard marine engine; 
         FIG. 4  is a cross-sectional view of a marine vapor separator according to the subject invention with the needle valve in an open position; and 
         FIG. 5  is a cross-sectional view of a marine valve vapor separator in a closed position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A vapor valve separator  28  for an engine  12  is generally illustrated in the figures. While  FIG. 1  illustrates an outboard marine engine  12  affixed to the transom  14  of a boat, the engine  12  may be any marine engine. Small outboard marine engines  12 , such as illustrated in  FIG. 2 , are usually mounted on a bracket  16  so that the engine  12  can be quickly removed from the boat for transportation and/or maintenance. The bracket  16  includes a tilting feature which allows the motor head to be rotated toward the boat with the propeller  18  swinging up out of the water to facilitate launching and maneuvering through shallow water conditions. As an example, the motor  12  may be pivoted about axis A between a use and a non-use provision, as well as for trim control. While the engine  12  is illustrated in  FIG. 2  as being an outboard motor, the vapor separator  28  of the present invention may be easily applied to inboard/outboard engines or inboard engines that are permanently affixed within compartments on the boat. 
     The marine engine  12  draws liquid fuel from a fuel tank  20  by an engine mounted fuel system generally shown as  22  in  FIG. 3 . While the fuel tank  20  is illustrated in  FIG. 2  as a smaller fuel tank, it should be readily recognized that any type of fuel tank including any size configuration or shape may be used with the present invention. Except for the fuel tank  20  and the supply line  24 , the fuel system  22  on marine engines is generally fully integrated with the engine  12  so that the components are located as close as possible to the engine to meet regulations such as that a high pressure fuel line must be no longer than eighteen inches. For the exemplary outboard motor  12  illustrated in  FIG. 2 , when the engine  12  is removed from the boat, the fuel system  22  may be removed with the engine  12 , however the fuel tank  20  and fuel line  24  may stay with the boat or be removed separately. However in some instances, the fuel tank  20  may also be removed along with the engine  12 . 
     As illustrated in  FIG. 3 , a low pressure fuel supply pump  26  or lift pump typically pulls fuel from the tank  20  through a supply line  24 . The fuel is delivered to a vapor separator, generally indicated in  FIGS. 3 and 4  as  28 . The vapor separator  28  collects and discharges vapors given off due to incoming low fuel pressure, normal vaporization of the fuel, vaporization due to proximity to the hot engine, and vaporization from hot agitated fuel returning from the engine under some circumstances. The high pressure pump  30  may be connected to the vapor separator  28  as shown in  FIG. 4  and pumps the fuel under pressure to the cylinders of the engine such as through a fuel injector system  32 . In some other embodiments, the high pressure pump  30  may not be directly connected to the vapor separator. Unused fuel may be returned to the vapor separator  28  via return line  34 . However in some embodiments, fuel is not returned to the vapor separator and the system does not include a return line. The vapor separator  28  further includes a vent device  36  which for most marine engines, including outboard engines, is provided with a vacuum fitting  38  for connection to the engine air intake system. The vacuum creates a negative pressure in the vent line  40  so that fuel vapors may be cycled through the air intake of the engine. 
     In an exemplary vapor separator  28  is depicted in  FIG. 4 , however one skilled in the art would readily recognize that the size, shape, and configuration of the vapor separator  28  may vary depending upon spacing, location, and engine requirements. The exemplary vapor separator  28  illustrated in  FIG. 4  includes an integral high pressure fuel pump  30 . The high pressure fuel pump  30  includes a fuel intake  42  and an outlet  44  which communicates with the fuel injector system  32 . Electrical power is supplied to the high pressure pump  30  through wires  46 . Although not illustrated in  FIG. 4 , the lift pump  26  or low pressure fuel pump can also be integrally included with the vapor separator  28 . In some embodiments a valve  76 , such as a Schrader valve, is provided at the top of the high pressure pump  30  to allow pressure testing of the outlet pressure. 
     The vapor separator  28  also includes in fluid communication with the high pressure pump  30  a hollow generally cylindrical housing  48  forming a hollow interior chamber  50 . A wall assembly  52  having a vapor outlet  68  is coupled to the cylindrical housing  48  and in the illustrated embodiment includes an O-ring  54  sealing the perimeter of the wall  52  against the housing  48  to create a liquid and vapor tight seal. Of course, a variety of other configurations may be used to assemble or create the hollow interior chamber  50  for retaining fuel and holding a vent valve device  36 . 
     As illustrated in  FIG. 4 , the housing  48  may also be coupled to a wall assembly having a fuel intake  78 . Of course, this wall assembly  56  may be formed integrally with the housing  48 . However, as illustrated in  FIG. 4 , an O-ring seal  58  may also seal the junction between the housing  48  and the wall assembly  56  to prevent liquid or vapor leakage. The vapor separator  28  may also include a mounting flange  60  for attachment to the engine  12 . The mounting flange  60  may be made in any size, shape, or configuration, however, is illustrated in  FIG. 4  as having an opening  62  including a rubber grommet  64  positioned within the opening  62  to provide isolation from vibration. 
     The vapor separator  28  includes the vent valve device  36 . The vent valve device  36  includes a biasing element such as a spring  98  for moving a needle valve  96  against a valve seat  85  on a vapor escape passage  84 . The vent valve  36  may be further configured to have a casing enclosing the needle valve  96  and biasing element  98 . The biasing element  98  typically biases the needle valve  96  against the valve seat  85  as the needle  96  is illustrated in  FIG. 5  in a closed position. The needle valve  96  may be formed out of a magnetic material so that a coil  94  surrounding the needle valve  96  may move the needle valve  96  from the biased closed position as illustrated in  FIG. 5  to an open position as illustrated in  FIG. 3 . In the opened position, fuel vapors may escape through the vapor escape passage  84  and out the vapor outlet  68 . The vent valve  36  further includes a fuel level detector  110  that may communicate with a control module (not shown) to control the coil  94 . In some embodiments, the fuel level detector  110  is connected to a relay (not shown) that switches the coil  94  on an off as needed. The fuel level detector  110  is typically a simple thermistor circuit the system and may include a time delay before activating the coil  94  to prevent accidental discharge of liquid fluid. Thus the vapor vent device  36  does not need a float assembly mounted to the biasing element  98 . Further, unlike the prior art where a biasing element biases the float in an open position or only biases toward closed in the presence of liquid fuel as it can not support the float in the absence of fuel, in the present invention, the biasing element biases the valve in a closed position even in the absence of fuel. 
     A valve  76  such as a Schrader valve may be positioned at the end of the fuel inlet channel for drainage and pressure release. The fuel inlet  78  for the low pressure pump  26  extends through the wall assembly  56  and communicates with the internal chamber  50 , typically through the hollow portion  74  of the wall assembly  56 . In some embodiments, an optional cooling coil  80  may be positioned within the chamber  50  to circulate cooling fluid and act as a heat exchanger for cooling the fuel contained within the chamber  50  to minimize vaporization. 
     To allow for easy assembly of the vapor separator  28 , the valve vent device  36  may include a casing (not illustrated) enclosing all of the parts. This casing allows for easy assembly by insertion into a cavity on the wall assembly  52  of the vapor separator  28 . 
     The biasing element  98 , even when fuel is not present, maintains the needle valve  96  in a closed position as illustrated in  FIG. 5  and in particular the point  95  of the needle valve  96  against the valve seat  85 . As the biasing element  98  normally biases the needle valve to a closed position, when the engine  12  is not operating and when electricity is not flowing to the coil  94 , the needle valve is maintained in a closed position against the valve seat  85 . When the engine  12  is in operation and power is supplied to the fuel level detector  110 , as long as the fuel level is higher than the fuel level detector  110 , the needle valve  96  will remain in the closed position as illustrated in  FIG. 5 . However, when the fuel level is below the fuel level detector  110 , the needle valve may be moved by the coil  94  into an open position as illustrated in  FIG. 3 . A time delay may be included in the fuel level detector circuit  110  to prevent the coil  94  from opening the needle valve  96  when fuel is temporarily not in contact with the fuel level detector  110  such as through vibrations or wave action or motion of the boat. For example, in water conditions including large waves the boat may significantly rock back and forth and the fuel level in the vapor valve separator  28  may intermittently not contact the fuel level detector  110  even though the fuel level is near the top of the vent valve device  36 . Due to this intermittent contact, if the time delay is not operational, and the coil  94  opens the needle valve  96  each time the fuel level detector  110  detected a low fuel level, at times liquid fuel may escape out of the vapor outlet  68  and enter the engine air intake system causing potentially a stalled engine. This is particularly troublesome in water conditions such as wavy conditions and therefore the fuel level detector  110  typically will include a time delay that ensures the fuel level actually is lower than the fuel level detector  110  to ensure that when the needle valve  96  opens only vapor escapes through the passage  68 . 
     The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.