Abstract:
A compact vapor separator for a fuel injection system reduces the size of the fuel system mounted on the side of an outboard engine. The girth of the outboard motor&#39;s power head consequently is decreased. In one embodiment, the vapor separator employs a plurality of rotary vane-type pumps. The pumps are sized to produce a sufficient flow rate and fuel pressure, while minimizing power consumption. At least one of the fuel pumps can be located on a periphery of a housing of the vapor separator and can be removably attached thereto to facilitate easy removal and assembly for service and repair. The vapor separator also can include a redundant seal arrangement to generally isolate an exterior casing of the fuel pump from the fuel and to seal an upper end of the housing. In another embodiment, a dividing wall separates the fuel pump from an fuel supply inlet of the fuel tank. The wall inhibits gas bubble migration toward the inlet of the fuel pump. The fuel pump thus draws less vapor.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to an internal combustion engine, and more particularly to a fuel injection system of an internal combustion engine. 
     2. Description of Related Art 
     Several outboard motors recently have become equipped with fuel injection systems in response to increased concerns regarding hydrocarbon emissions. Such systems, which are monitored and controlled by an electronic control unit, significantly reduce hydrocarbon emissions, while improving fuel economy and performance. 
     Fuel injection system typically include a vapor separator and a high-pressure pump. The pump delivers pressurized fuel to the individual fuel injectors. An engine typically includes one, and sometimes two fuel injectors per cylinder. The pump must be of a sufficient size to supply fuel to the injectors at a desired pressure, while producing a significant flow rate through a fuel recirculation branch of the fuel delivery system to reduce the temperature of the fuel at the inlet to the fuel injector. Prior fuel delivery systems thus have included a large centrifugal type (e.g. Wesco-type) fuel pump in order to meet these needs. 
     Large-size pumps, however, generally increase the size of the engine, and thus the size of the power head. The power head of an outboard motor generally extends above the transom of the watercraft and, consequently, the power head produces aerodynamic drag on the watercraft as the watercraft speeds over the water. The size and shape of the power head directly affect the amount of drag produced. A large-size pump thus negatively increases the drag experienced by the outboard motor. 
     Many outboard motors which employ fuel injection system use an integrated vapor separator/fuel pump assembly. That is, a single housing encloses the fuel tank of the vapor separator and the fuel pump. The fuel pump draws fuel directly from the fuel tank. Although this design somewhat reduces the size of these components, the integrated design makes it difficult to service or repair the pump. A service technician must remove the entire housing and then disassemble the housing in order to gain access to the pump. This act commonly destroys the housing seal. The technician must then disconnect and remove the pump from the housing. After servicing, the technician reassembles the unit in the reverse manner, replacing the housing seal. These steps overly complicate the assembly and service procedures, and add cost to the service and maintenance of the outboard motor. 
     Another drawback of prior unitary vapor separator/fuel pump assemblies resides with the position of the pump inlet relative to the fuel tank of the vapor separator. Fuel vapor and air are separated from liquid fuel in the fuel tank of the vapor separator. The influent port to the fuel pump, which also commonly is located in the fuel tank, tends to draw in gas bubbles before the bubbles surface in the fuel tank of the vapor separator, especially where the pump influent port lies near the point where the fuel enters the tank through the supply inlet port. Vapor bubbles in the fuel line significantly alters the fuel ratio of the fuel/air charge delivered to the cylinder combustion chambers. Inefficiencies and rough running of the engine result from this effect. In addition, in some fuel delivery systems, the bubbles can produce a vapor-lock and prevent fuel flow through the high-pressure portion of the fuel delivery system. 
     SUMMARY OF THE INVENTION 
     A need therefore exists for a compact, sealed vapor separator which facilitates convenient removal and assembly of the fuel pump for service and repair. The fuel pump of the vapor separator desirably meets the desired fuel flow and pressure design criteria and is arranged in the vapor separator assembly to inhibit the intake of vapor bubbles into the high-pressure fuel circuit of the fuel delivery system. 
     One aspect of the present invention involves a vapor separator assembly for a fuel delivery system used with an internal combustion engine. The vapor separator assembly comprises a housing that defines an internal fuel tank enclosed within the housing. A plurality of fuel pump are supported within the housing. Each fuel pump communicates with the fuel tank and with a return inlet port that flows into the fuel tank. 
     In one embodiment, the fuel pumps are centrifugal, rotary-vane type fuel pumps. The pumps are sized so as to together produce a sufficient flow rate and fuel pressure. Two small fuel pumps thus can replace one large fuel pump. With centrifugal, rotary-vane type fuel pumps (e.g., Wesco-type fuel pumps), the pumps can be downsized to one-fourth of the size of the convention single fuel pump. As a result, the fuel pump system can be downsized to one-half of the conventional size, thereby reducing the size of the vapor separator assembly. Two small pumps also consume less power than a single large conventional rotary-vane type fuel pump. 
     In accordance with another aspect of the present invention, a vapor separator assembly is provided for a fuel delivery system used with an internal combustion engine. The vapor separator assembly comprises a housing defining an internal fuel tank which is enclosed within the housing. A fuel pump is supported within the housing. The fuel pump is a roller-vane type fuel pump and communicates with the fuel tank. 
     Another aspect of the present invention involves a vapor separator assembly for a fuel delivery system used with an internal combustion engine. The vapor separator assembly includes a housing that defines an internal fuel tank. The fuel tank is enclosed within the housing. At least one fuel pump is supported by the housing with a portion of the pump being exposed outside the housing. A releasable coupling interconnects the pump and the housing to place the pump in communication with the fuel tank. 
     An additional aspect of the present invention involves a vapor separator assembly for a fuel delivery system used with an internal combustion engine. The vapor separator assembly comprises first and second fuel tanks which communicate with one another. A fuel inlet communicates with the first fuel tank, and at least one fuel pump communicates with the second fuel tank. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate and not to limit the invention, and in which: 
     FIG. 1 is a side elevational view of an outboard motor on which the present vapor separator can be employed; 
     FIG. 2 is a plan, cross-sectional view of an engine of the outboard motor of FIG. 1, illustrating the location of the vapor separator on the engine; 
     FIG. 3 is a side, cross-sectional view of a conventional vapor separator; 
     FIG. 4 is a side, cross-sectional view of the vapor separator which is configured in accordance with a preferred embodiment of the present invention; 
     FIG. 5 is a top plan view of the vapor separator of FIG. 4; 
     FIG. 6 is a side, cross-sectional view of the vapor separator which is configured in accordance with another preferred embodiment of the present invention; 
     FIG. 7 is a top plan view of the vapor separator of FIG. 6; 
     FIG. 8 is a side, cross-sectional view of the vapor separator which is configured in accordance with an additional preferred embodiment of the present invention; 
     FIG. 9 is a top plan view of the vapor separator of FIG. 8; 
     FIG. 10 is a side, cross-sectional view of the vapor separator which is configured in accordance with a further preferred embodiment of the present invention; 
     FIG. 11 is a top plan view of the vapor separator of FIG. 10; 
     FIG. 12 is a side, cross-sectional view of the vapor separator which is configured in accordance with another preferred embodiment of the present invention; 
     FIG. 13 is a top plan view of the vapor separator of FIG. 12; 
     FIG. 14 is a side, cross-sectional view of the vapor separator which is configured in accordance with an additional preferred embodiment of the present invention; 
     FIG. 15 is a top plan view of the vapor separator of FIG. 14; 
     FIG. 16 is a side, cross-sectional view of the vapor separator which is configured in accordance with a further preferred embodiment of the present invention; 
     FIG. 17 is a top plan view of the vapor separator of FIG. 16; 
     FIG. 18 is a side, cross-sectional view of the vapor separator which is configured in accordance with another preferred embodiment of the present invention; 
     FIG. 19 is a top plan view of the vapor separator of FIG. 18; 
     FIG. 20 is a side, cross-sectional view of the vapor separator which is configured in accordance with an additional preferred embodiment of the present invention; 
     FIG. 21 is a top plan view of the vapor separator of FIG. 20; 
     FIG. 22 is a partial top, cross-sectional view of an engine to which the vapor separator of FIGS. 20 and 21 is attached; 
     FIG. 23 is a side, cross-sectional view of the vapor separator which is configured in accordance with another preferred embodiment of the present invention; and 
     FIG. 24 is a side, cross-sectional view of the vapor separator which is configured in accordance with a further preferred embodiment of the present invention; and 
     FIG. 25 is a top plan view of the vapor separator of FIG. 24. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 illustrates an outboard drive 10 which incorporates a fuel separator configured in accordance with the present invention. Because the present vapor separator has particular utility with an outboard motor, the vapor separator is described below in connection with an outboard motor 10; however, the depiction of the invention in conjunction with an outboard motor is merely exemplary. Those skilled in the art will readily appreciate that the present vapor separator can be used with an inboard motor of an inboard/outboard drive, to an inboard motor of a personal watercraft, and to other types of watercraft engines as well. 
     The outboard motor 10 includes a power head that comprises a powering internal combustion engine 12 and a surrounding protective cowling. The cowling includes a main cowling portion 14 that is detachably connected to a tray portion 16. 
     As is typical with outboard motor practice, the engine 12 is supported within the power head so that its output shaft, a crankshaft indicated by the reference numeral 18 in FIG. 2, rotates about a vertically extending axis. This output shaft or crankshaft 18 is rotatably coupled to a drive shaft (not shown) that depends into and is journaled within a drive shaft housing 20. The tray 16 encircles the upper portion of the drive shaft housing 20. 
     The drive shaft continues into a lower unit 22 where it can selectively be coupled to a propeller 24 for driving the propeller 24 in selected forward or reverse direction so as to so propel an associated load, namely, a watercraft 26. A conventional forward-reverse bevel gear transmission (not shown) is provided for this purpose between the drive shaft and a propeller shaft. The propeller shaft drives the propeller in a known suitable manner. 
     A steering shaft (not shown) having a tiller 28 affixed to its upper end is attached by means which include a lower bracket assembly 30 to the drive shaft housing 20. This steering shaft is journaled within a swivel bracket 32 for steering of the outboard motor 10 about a vertically extending axis defined by the steering shaft. 
     The swivel bracket 32 is, in turn, connected to a clamping bracket 34 by a trim pin 36. This pivotal connection permits tilt and trim motion of the outboard motor 10 relative to the associated transom 38 of the watercraft 26 to which the clamping bracket 34 is mounted. 
     The construction of the outboard motor 10 as thus far described may be considered to be conventional, and for that reason further details of this construction are not believed necessary to permit those skilled in the art to practice the invention. 
     In order to facilitate the description of the present invention, the terms &#34;front&#34; and &#34;rear&#34; are used to indicate the relative sides of the components of the engine and the vapor separator. As used herein, &#34;front&#34; refers to that side closes to the transom 38 of the watercraft 26, while &#34;rear&#34; refers to that side away from the transom 38. FIG. 2 includes similar labels to further aid the reader&#39;s understanding. 
     With reference to FIG. 2, the engine 12 is, in the illustrated embodiment, a reciprocating multi-cylinder engine operating on a two-cycle crankcase compression principle. The engine 12 has a V-type configuration, though it will be readily apparent to those skilled in the art how the invention may be utilized with engines having other cylinder arrangements, such as, for example, in-line or slant cylinder arrangements, and operate on other than a two-cycle crankcase compression principle, such as, for example, a four-cycle principle. 
     The engine 12 is provided with a cylinder block assembly 40 that lies generally within the center of the power head. The cylinder block 40 includes a pair of inclined cylinder banks 42 which extend at an angle relative to each other to give the engine a conventional V-type configuration. 
     Each cylinder bank 42 includes a plurality of parallel cylinder bores 44 that are formed by cylinder liners 46. Each cylinder liner 46 is cast or pressed in place in a cylinder bank 42. Pistons 48 reciprocate within the bores 44 and are rotatably journaled about the small ends of connecting rods 50 by means of piston pins 52. The big ends of the connecting rods 50 in turn are journaled about throws 54 of the crankshaft 18. 
     As is typical with V-type engine arrangements, the cylinder bores 44 of the first cylinder bank 42 are offset slightly in the vertical direction from the cylinder bores 44 of the second cylinder bank 42 so that the connecting rods 50 of adjacent cylinder bores 44 can be journaled on the same throw 54 of the crankshaft 18, as shown in FIG. 2. 
     The crankshaft 18 is rotatably journaled within a crankcase chamber 56, formed at the lower ends of the cylinder bores 44. The crankcase chambers 56 are formed by the skirt of the cylinder block 40 and a crankcase member 58 that is affixed to the cylinder block 40 in any well-known manner. As has been noted, the engine 12 operates on a two-cycle crankcase compression principle. As is typical with such engines, the crankcase chambers 56 associated with each of the cylinder bores 44 are sealed relative to each other in a manner which includes the utilization of sealing disks 60 provided on the crankshaft 18. These disks 60 are disposed on the throws 54 of the crankshaft 18 and separate the big ends of adjacent connecting rods 50. 
     A supply of atmospheric air is delivered to the crankcase chambers 56 by an induction system that is indicated generally by the reference numeral 62. The induction system 62 is composed of a plenum chamber 64 that includes forward and rearward portions 66 and 68, respectively, that are affixed to each other by any suitable means. The plenum chamber 64 receives a supply of atmospheric air through an opening (not shown) formed in the main cowling portion 14 of the power head. This air is then delivered to a number of adjacent throttle body assemblies 70, of which in FIG. 2 a single assembly is shown and associated with the adjacent cylinder bores 44 illustrated. 
     The throttle body assembly 70 is composed of a housing 72 in which is positioned a butterfly-type throttle valve assembly 74 for regulating the air flow through the throttle body 70. The throttle valve assembly 74 includes a valve 76 that is affixed to a shaft 78 which is, in turn, rotatably journaled within the housing 72 and affixed at one end to a manually operated throttle control 80. The throttle control 80 is provided with a throttle position sensor 82 which signals an electronic control unit ECU (not shown). The throttle control 80 is affixed to the throttle housing 70 by a bolt 83. 
     At its end opposite the plenum chamber 64, the throttle body 70 is affixed to an intake housing 84 by means of bolts 86 which extend through the housing 84 and into the end of the crankcase member 58 opposite of the cylinder block 40. Thus, the throttle body housing 70, intake housing 84, and forward end of the crankcase member 58 together comprise an intake passage 88 which delivers atmospheric air to the crankcase chamber 56. 
     A reed-type check valve 90 is disposed within the intake passage 88 at the junction between the intake housing 84 and the crankcase member 58 and operates to preclude reverse air flow in a known manner. 
     Fuel is supplied to the air charge admitted, as thus far described, by a fuel injector that is indicated by the reference numeral 92 and mounted within the throttle body housing 72 downstream of the throttle valve 74. The fuel injector 92 receives a supply of fuel from a fuel delivery system which is composed of a fuel tank (not shown) that is mounted within the hull of the associated watercraft 26 and delivers fuel to a low-pressure fuel pump 94 positioned along the side of the engine 12, as seen in FIG. 2, through a conduit (not shown). 
     A fuel filter 96 is positioned adjacent to the low-pressure fuel pump 94 and receives fuel from the fuel tank as the pump 94 draws the fuel through a conduit (not shown). The fuel filter 96 separates water and other contaminants from the fuel. From the fuel filter 96 and fuel pump 94, the fuel enters an additional conduit (not shown) which traverses the engine 12 and opens to a vapor separator assembly 98. The vapor separator separates fuel vapor and other gases from the liquid fuel, and will be discussed in detail below. Bolts 100 secure the vapor separator 98 to a mounting bracket 102, which in turn is affixed to the side of the throttle housing 72 adjacent to the fuel injector 92 by any suitable means. In the illustrated embodiment, the vapor separator 98 lies on a side of the induction system 62 opposite of the side on which the low-pressure pump 94 is located. 
     Fuel is pumped from the vapor separator 98 through a conduit (not shown) to the lower end of a vertically extending fuel rail 104 by a high-pressure pump 106. The high-pressure pump 106 forms a portion of the vapor separator assembly 98. The fuel rail 104 delivers fuel to each of the fuel injectors 92. For this purpose the fuel rail 104 communicates with a plurality of supply ports (not shown) provided along the length of the fuel rail 104, each of which communicates with a fuel injector to supply the fuel injector 92 with fuel. 
     A fuel return line (not shown) extends between an outlet port of the fuel rail 104 and the vapor separator 98. The return line completes a fuel flow loop that generally maintains a constant flow of fuel through the fuel rail 104. This constant fuel flow inhibits heat transfer to the fuel, and thus reduces fuel vaporization within the fuel rail 104. The vertical orientation of the fuel rail 104 also facilitates separation of any fuel vapor which occurs downstream of the vapor separator 98 from the fuel flow into the fuel injectors 92. 
     A pressure regulator (not shown) desirably lies within the above fuel flow loop and maintains a uniform fuel pressure at the injectors 92, e.g., 50-100 atm. The regulator regulates the fuel pressure by dumping excess fuel back to the vapor separator 98, as is well known in the art. 
     A pair of cylinder head assemblies 108 are affixed in closing relation to the ends of the cylinder bores 44 opposite to the ends that open to the crankcase chamber 56 by any suitable means. The cylinder heads 108 define a recess which operates with the bores 44 and heads of the pistons 48 to form combustion chambers 110, whose volume varies cyclicly with the motion of the pistons 48. A spark plug 112 is mounted atop each of the cylinder heads 108 and has its gap extending into the combustion chamber 110. The spark plugs 112 are fired by an ignition control circuit (not shown) that is controlled by the ECU. The open upper ends of the cylinder heads 108 are sealed by covers 113 that are affixed to the cylinder heads 108 by any suitable means. 
     Exhaust passages 114 are formed along each cylinder bank 42 along the sides which face the opposite cylinder bank 44. The exhaust passages 114 open to the cylinder bores 44 at a position that is approximately half way along the longitudinal bore 44. The exhaust passages 114 of opposite cylinder banks 42 extend towards each other and merge to form an exhaust manifold 116, which routes exhaust gases through an exhaust system (not shown) for purification before being expelled from the outboard motor 10. 
     One or more scavenge passages (not shown) are formed within each cylinder bank 42. Each passage includes an inlet port 118 which is disposed in the lower end of the bore 44 and opens to the crankcase chamber 56, and an outlet port 120 which is disposed at a longitudinal position along the bores 44 that is slightly below and on the opposite side of the exhaust passage 114 and opens to each of the bores 44. 
     The above-described engine 12 operates in the following manner. Upward motion of the piston 48 draws atmospheric air and injected fuel from the fuel injector 92 through the induction passage 88 and into the crankcase chamber 56, past the reed valve 90. The reed valve 90 is open at this point, because the pressure in the induction passage 88 is greater than the pressure in the crankcase chamber 56. 
     Sometime after the piston 48 passes top dead center (TDC), the pressure in the crankcase chamber 56 will exceed the induction passage pressure, and the reed valve 90 will close. The air-fuel mixture in the crankcase chamber 56 is then compressed by the piston 48 during its downstroke until the outlet port 120 of the scavenge passage is exposed to the combustion chamber 110. At this point the compressed air-fuel mixture enters the combustion chamber 110 through the scavenge passage and is further compressed by the ensuing compression stroke of the piston 48. 
     At some point before top dead center (TDC), the spark plug 112 is fired by the ECU, and the air-fuel mixture ignites, burns, and expands. This forces the piston 48 downwardly, and thus drives the crankshaft 18. Continued downward motion of the piston 48 exposes the exhaust passage 114 to the combustion chamber 110, and thus permits the combustion gases to be expelled from the combustion chamber 110 through the exhaust passage 114. 
     Before describing the present fuel vapor separator 98 in detail, a conventional vapor separator will first be described in order for the reader to appreciate the advantages of the present vapor separator 98. Because many of the components of the present vapor separator and the conventional vapor separator will be the same or substantially similar, like reference numerals will be used to indicate similar components between the conventional vapor separator and the present vapor separator. An &#34;a&#34; suffix will be later added to the similar components of the present vapor separator in order to distinguish the two designs. 
     A conventional fuel vapor separator will now be discussed in detail. FIG. 3 illustrates the conventional vapor separator which as previously stated separates fuel vapor and other gases from the liquid fuel supply to the injectors 92. The vapor separator includes a cover 124 that is affixed by bolts 126 to a bowl 128. The cover 124 and bowl 128 form a large housing. The housing generally defines a fully enclosed fuel tank or internal cavity 130. Fuel is supplied from the low pressure fuel pump 94 to the fuel tank 130 past a metering system 132 which includes a needle valve 134 and float 136 for controlling the fuel flow into the fuel tank 130. 
     A high pressure, centrifugal, rotary-vane type pump 138 (e.g., a Wesco-type fuel pump) is submerged within the fuel tank 130 and pumps fuel to the fuel rail 104. The Wesco-type fuel pump 138 is an impeller type rotary-vane pump. Such prior pumps often are large in physical size in order to produce a desired fuel flow rate and fuel pressure due to inefficiencies in this type of pump. The shortcomings of the conventional large, centrifugal-type pump will be described in further detail below. 
     An O-ring seal 140 sealingly engages the upper end of the fuel pump 138. The seal 140 is pressed against the lower surface of the cover 124 so as to prevent fuel from leaking out of the fuel tank 130 past the fuel pump 138. 
     A number of additional problems exist with the above-described conventional vapor separator. For instance, while the seal 140 generally inhibit fuel from leaking past the high-pressure fuel pump 138 and through the cover 124, it is still possible that the fuel may leak out of the vapor separator 98 at the junction between the cover 124 and bowl 128. This is especially possible in those circumstances where the outboard motor 10 is tilted to an out-of-the-water condition (i.e., full tilt-up position) where the level of the fuel can be above the junction of the cover 124 and bowl 128. An embodiment of this invention described below precludes this possibility by isolating the high pressure fuel pump 138 from the fuel in the cavity 130. 
     With reference now to FIGS. 4 and 5, a vapor separator assembly 98a is constructed in accordance with an embodiment of the invention. The vapor separator 98a includes a cover 124a that is affixed by bolts 126a to the open upper end of the bowl 128a. The bowl 128a has a mounting plate portion 142 formed integrally along its inward wall as seen in FIG. 4 which serves as the means by which the vapor separator assembly 98a is affixed to the mounting bracket 102a. The cover 124a and the bowl 128a together define the fuel tank or internal cavity 130a which receives a supply of fuel through a conduit from the low pressure fuel pump 94. 
     The conduit sealingly engages a fuel supply inlet port 144 which is integrally formed within the cover 128a and communicates with a fuel inlet passage 146. The fuel inlet passage 146 opens to the internal cavity 130a and thus allows for the filling of the bowl 128a with fuel. 
     The level of fuel within the cavity 130a is controlled by the float-type metering system 132a disposed within the cavity 130a. The metering system 132a includes the float 136a that is rigidly affixed to the pivot arm 148 which is, in turn, pivotally connected to the bottom surface of the cover 124a by a bracket 150. The needle valve 134a is disposed atop the pivot arm 148 and extends upwardly towards a constricted portion 152 (i.e., valve seat) of the fuel inlet passage 146. 
     The above-described fuel metering system 132a functions in the following manner. As fuel is pumped into the cavity 130a by the low-pressure fuel pump 94 the level of the fuel within the bowl 128a rises. This causes the float 136a to rise which, in turn, causes the needle valve 134a to extend further upward towards the constricted portion 152 of the fuel inlet passage 146. Once the fuel in the bowl 128a is at a predetermined desired level the needle valve 134a will be disposed within the passage 146 so as to impinge against the constricted portion 152 to prevent any further fuel flow into the bowl 128a. When the fuel level drops the needle 134a no longer contacts the constricted portion 152 and fuel flows past the needle valve 134a into the cavity 130a. 
     An oil inlet port 154 is integrally formed within the bottom of the bowl 128a. The oil inlet port 154 opens to the cavity 130a and sealingly engages the oil conduit for providing a supply of oil from the oil tank to the vapor separator 98a. 
     A strainer 156 is disposed at the bottom of the bowl 128a adjacent to the oil inlet fitting 154 and draws fuel and oil from the cavity 130a. The bottom surface of the bowl 128a against which the strainer 156 lies slopes downwardly in the forward direction and thus disposes the strainer 156 within the bowl 128a at some angle from horizontal. The strainer 156 strains any remaining impurities from both the oil and the fuel and supplies an influent port 158 of the high pressure fuel pump 138a. 
     An electric fuel pump 138a draws fuel from the fuel tank 130a. In the illustrated embodiment, the fuel pump 138a desirably is of a roller-vane type configuration and utilizes sliding rollers as the rotary means by which the fuel and oil is pumped. In other words, the roller-vane type pump 138a is a positive displacement pump (i.e., each pump rotation moves a specific amount of fuel). Small rollers and an offset mounted rotor disc produce fuel pressure. When the rotor disc and rollers spin, they pull fuel in on one side. Then the fuel is trapped and pushed to a smaller area on the opposite side of the pump housing. This compresses the fuel between the rollers, and the fuel flows under pressure. 
     In the alternative, a sliding vane type fuel pump can be used. The sliding vane fuel pump function much in the same manner as the roller vane fuel pump, but sliding vanes (i.e., blades) are used instead of rollers. Both of these types of fuel pump are very efficient, but are somewhat large in size. 
     As seen in FIG. 3, the fuel pump 138a has an external casing and is disposed within the cavity 130a. The fuel pump 138a is affixed at its lower end to the bowl 128a by a bolt 160. The upper end of the fuel pump 138a is sealingly engaged by the O-ring seal 140a which is pressed against the lower surface of the cover plate 124a to provide a leak-proof seal thereto and prevents fuel and oil exiting the chamber 130a past the fuel pump 138a. 
     A pair of electrical terminals 161 are positioned at the upper end of the fuel pump 138a. The terminals 161 extend upward through the cover 124a and are coupled to electrical wires leading from an electrical source (e.g., a battery or generator) to supply electrical power to the rotary motor of the fuel pump 138a. 
     A fuel pump discharge port 162 is also positioned at the upper end of the fuel pump 138a adjacent to the terminals 161 and extends upwards through the cover plate 124a. The discharge port 162 sealingly engages a conduit through which fuel is pumped by the high pressure fuel pump 138a to the fuel rail 104. 
     A fuel return inlet port 164 is integrally formed within the cover 124a adjacent to the fuel inlet port 144 and opens to the cavity 130a. The fuel return inlet port 164 is sealingly engaged by the fuel return line that extends between the fuel rail 104 and the vapor separator 98a and returns excess fuel regulated by the pressure regulator to the cavity 130a. 
     A vapor vent port 166 is integrally formed within the cover 124a adjacent to the return inlet port 164 and opens to the uppermost portion of the cavity 130a which is henceforth referred to as the vapor cavity and indicated by the reference numeral 168. A vent conduit (not shown) sealingly engages the vapor vent port 166 and terminates at the induction system for the engine 12. Fuel vapors and other gases from the fuel in the bowl 128a will rise into the vapor cavity 168 and be routed to the induction system in a conventional manner. 
     An oil return port 169 is disposed within the cover 124a in side-by-side relationship with the vapor vent port 166 and returns oil from the engine 12 through a conduit (not shown) to the vapor separator assembly 98a. 
     An internal dividing wall 170 extends within the bowl 128a and separates the high-pressure fuel pump 138a from the cavity 130a. A further O-ring seal 172 sealingly engages the lower end of the fuel pump 138a and is pressed against the rearward surface of the bowl 128a and the wall 170 so as to provide a redundant, generally leak-proof seal which maintains separation between the fuel and oil in the chamber 130a and all but the lower portion of the fuel pump 138a. 
     The lower end of the fuel pump 138a is affixed to the bowl 128a by the screw 160 that extends horizontally through the bowl 128a because the bowl mounting surface for the fuel pump lower surface is minimized so as to allow the influent port 158 to be centrally positioned on the underside of the high pressure fuel pump 138a. 
     The vapor separator 98a described above precludes fuel from leaking past the junction between the cover 124a and the bowl 128a because the seal 172 prevents the fuel and oil in the cavity 130a from approaching the junction, even when the outboard motor 10 is in a fully trimmed-down position. The above vapor separator 98a offers a further advantage in that the wall 170 reduces the likelihood of air bubbles or vapor entering the fuel pump 138a, which results in the high pressure fuel pump 138a drawing in less air and vapor. Also, the proximity of the fuel in the bowl 128a to the fuel pump 138a reduces the noise emissions from and cools the fuel pump 138a. The cooling of the fuel pump does heat the fuel in the bowl 128a, but not sufficiently high so as to cause fuel vaporization to occur. 
     In the following embodiments, many of the components of the vapor separator will be similar to those described above. Accordingly, the following description will use the same reference numeral to indicate like components between the embodiments, but with each embodiment using a different suffix letter. It is intended that unless indicated otherwise, the first description of a component will apply equally to similar components in all subsequently embodiments for brevity. 
     FIGS. 6 and 7 illustrate another vapor separator 98b that is identical to the vapor separator 98a of FIGS. 4 and 5 but with a second strainer 156b and high pressure fuel pump 138b added. The second fuel pump 138b is also a roller-vane type pump and is disposed within the rearward portion of the bowl 128b and separated and sealed from the cavity 130b by a further internal wall 170b and O-ring seal 172b. The single oil inlet port 154b is disposed at the rearward lower end of the bowl 128b adjacent to the second strainer 156b while a wall 180 extends upwardly between the strainers 156b and terminates within the cavity 130b below the float 136b. 
     The above-described vapor separator 98b offers the same advantages as the previous embodiments because both of the fuel pumps 138b are isolated from the cavity 130b by the seals 172b and the walls 170b reduce the likelihood of air and fuel vapor entering either of the fuel pumps 138b. Of course, the above configuration also provides for greater fuel recirculation which results in cooler fuel flow within the fuel rail 104 and thus reduces the likelihood of vapors forming within the fuel rail 104. 
     Because the available space within the power head of the outboard motor 10 is limited it is highly desirable to provide a vapor separator assembly which is compact in design and therefore more readily packaged within the space available. A further embodiment of this invention addresses this by providing a physically compact configuration for the vapor separator which may be more easily accommodated within the power head of the outboard motor 10. 
     FIGS. 8 and 9 illustrate another embodiment of a vapor separator 98c in which the high-pressure fuel pump 138c is disposed within the bowl 128c near the central portion of the internal cavity 130c. Again the fuel pump 138c is of a roller-vane type configuration with the fuel outlet port 162c and terminals 161c extend upwardly out of the cover plate 124c adjacent to the fuel inlet port 144c. The fuel inlet port 144c has itself been moved rearwardly to a side-by-side position with the fuel return inlet port 164c in order to reduce the length of the vapor separator 98c. The vapor vent port 166c and oil return port 169c are disposed at the forward-most portion of the cover 124c as is the vent cavity 168c. 
     As best seen in FIG. 9, the float 136c is provided with an opening 190 through which the fuel pump 138c extends. With this configuration, the fuel pump 138c is positioned within the cavity 130c. An O-ring seal 140c sealingly engages the upper end of the fuel pump 138c and the lower surface of the cover plate 124c to prevent fuel and oil from exiting the internal cavity 130c past the fuel pump 138c. 
     The strainer 156c is positioned at the bottom of the bowl 128c generally forwardly of the fuel pump 138c with its rearward end lower than its forward end because the lower surface of the bowl 128c against which the strainer 156c lies extends upwardly in the forward direction. The fuel pump influent port 158c extends upwardly from the rear of the strainer 156c and sealingly engages the front of the lower end of the high pressure fuel pump 138c which is affixed to the lower surface of the bowl 128c by the vertically extending bolt 160c. The oil inlet port 154c is integrally formed within the bottom of the bowl 128c to the rear of the strainer 156c on the side opposite the fuel pump influent port 158c. 
     As apparent from FIG. 9, the length of the above-described vapor separator 98c is greatly reduced because the fuel pump 138c extends through the float opening 190 and the fuel inlet port 144c has been moved rearwardly. 
     FIGS. 10 and 11 illustrate a further compact vapor separator configuration which utilizes two small, centrifugal, rotary-vane type fuel pumps 138d (e.g., Wesco-type fuel pumps) . As previously stated, the Wesco-type fuel pump is a rotary-vane type pump which utilizes an impeller as the rotary pumping means. This differs from a roller-vane type pump in that the vanes of a rotary-vane do not contact the inner wall of the pump volute. Pump inefficiencies therefore result. The Wesco-type impeller pump also draws more power from the electrical power source and is therefore less efficient. 
     The Wesco-type fuel pumps 138d shown in FIGS. 10 and 11, however, are smaller than the roller-vane pumps utilized in previous embodiments and draw less power. The pumps are sized so as to together produce a sufficient flow rate and fuel pressure. Two small centrifugal fuel pumps thus can replace one large centrifugal or roller-vane fuel pump. With the Wesco-type fuel pumps, the pumps can be downsized to one-fourth of the size of the convention single Wesco-type fuel pump. As a result, the fuel pump system can be downsized to one-half of the conventional size, thereby reducing the size of the vapor separator assembly. Two small pumps also consume less power than a single large conventional Wesco-type fuel pump. 
     With reference to FIG. 10, the vapor separator 98d is similar to the vapor separator 98b of FIGS. 6 and 7 with the fuel pumps 138d positioned within the internal cavity 130d. Because there are no internal walls the length of the cover 124d and bowl 128d is reduced and the high pressure fuel pumps 138d and strainers 156d are brought closer together such that the adjacent ends of the strainers 156d are disposed in proximity to or touching the vertical wall 180d. The fuel pump influent ports 158d extend upwardly from the lower end of the strainers 156d to sealingly engage the lower ends of the fuel pumps 138d on their inboard sides. The outboard sides of the lower ends of the fuel pumps 138d are each affixed to the bottom of the bowl 128d by the bolts 160d. 
     Under some circumstances it will be necessary to access the high pressure fuel pump such as when, for example, the pump requires service or repair. It is therefore desirable to have a vapor separator in which the fuel pump is readily accessible. An embodiment of this invention provides a vapor separator assembly which has the fuel pump detachably mounted to an external side of the vapor separator where it is easily accessible for service or repair. 
     FIGS. 12 and 13 illustrate a vapor separator 98e that resembles the vapor separator 98 of FIG. 4 but with the high pressure fuel pump 138e mounted on the outer peripheral wall of the bowl 128e. The bowl 128e includes an external boss portion 200 above which is positioned the fuel pump 138e and through which extends an effluent conduit 202 that communicates with an outlet end 203 of the strainer 156e. 
     The high pressure fuel pump 138e is affixed to the outside of the bowl 128e by a releasable coupling assembly 204. In the illustrated embodiment, the releasable coupling includes a receptacle port 205 formed in the boss portion 200 of the housing 128e. The receptacle port 205 is sized to receive a port hub 207 formed on a lower end of the fuel pump 138e. The port hub 207 frictionally engages the receptacle port 205 to releasably connect the fuel pump 138e to the housing 128e, as well as to seal the interconnection. In the alternative, the lower end of the fuel pump 138e can include a receptacle port with the port hub being formed on boss portion 200. The receptacle port 205 communicates with the conduit 202 formed in the boss portion 200 to place the fuel pump 138e in communication with the strainer 156e. 
     A retainer strap 206 bounds the lower perimeter of the fuel pump 138e and holds the fuel pump 138e in pressing engagement with the front surface of the bowl 124e. Openings are provided at the ends of the retainer strap 206 through which screws 208 extend and threadingly engage the bowl 128e. At least one end of the retainer strap 206 desirably is easily accessible so as to release the fuel pump 138e. 
     With the above-described vapor separator configuration, the high-pressure fuel pump 138e is easily removable by unscrewing the screws 208 and removing at least an end of the retainer strap 206. The fuel pump 138e may then be manually separated from its connection to the fuel pump supply conduit 202 and removed from the vapor separator 98e. 
     FIGS. 14 and 15 illustrate a vapor separator 98f that is similar to the vapor separator 98e of FIGS. 12 and 13 but which utilizes a second fuel pump 138f disposed at the rearward external end of the bowl 128f and mounted thereto with a second coupling assembly 204f. As mentioned above, it is understood that the above description of the common components will apply equally to this embodiment, unless indicated to the contrary. 
     A second strainer 156f is disposed within the cavity 130f and supplies the rearward fuel pump 138f with fuel through a further elongated influent port 202f. As seen in FIG. 14, the oil inlet port 154f is disposed within the bowl 128f at the lower rearward portion of the cavity 130f adjacent to the second strainer 156f. It should also be noted that the strainers 150f are disposed in a staggered relationship with each other which allows for a reduction in the length of the vapor separator 98f because the strainers 156f now overlap. 
     FIGS. 16 and 17 illustrate a vapor separator 98g similar to the vapor separator 98e of FIGS. 12 and 13 but which utilizes a Wesco-type rotary vane, high-pressure fuel pump 138g. A port hub or spacer 210 is interposed between the retainer 206g and the fuel pump 138g so as to maintain a pressing engagement between the coupling assembly 204g and the fuel pump 138g. 
     The lower end of the fuel pump 138g extends into the internal cavity 130g through an opening 212 formed in the front of the bowl 128g. An O-ring seal 214 sealingly engages the lower end of the fuel pump 138g and is pressed against the walls of the opening 212 and thus prevents any leaking of fuel and oil past the fuel pump 138g. 
     The fuel pump 138g is provided with a lower external portion 216 along its lower surface that is sealingly engaged by the fuel pump influent port 202g for supplying fuel to the fuel pump 138g. 
     With the above configuration, the fuel pump 138g is easily removed from the vapor separator 98g by unscrewing the screws 208g and removing the retainer strap 206g and spacer 210. The Wesco-type fuel pump 138g may then be manually separated from the conduit 202g and seal 214 and removed from the vapor separator 98g. Care should be taken, however, when replacing the fuel pump 138g to ensure a sealing contact between the fuel pump 138g and the seal 214. 
     FIGS. 18 and 19 illustrate a vapor separator assembly 98h similar to the vapor separator 98g but which utilizes a second Wesco-type fuel pump 138h mounted in like manner to the first fuel pump 138h. The vapor separator 98h also utilizes two strainers 156h in staggered relationship to each other like the vapor separator 98f of FIGS. 14 and 15 so as to reduce the overall length of the vapor separator 98h. Also the oil inlet port 154h is disposed in the lower surface of the bowl 128h adjacent to the second strainer 156h. 
     Because the Wesco-type fuel pumps 138h are smaller the above configuration provides for a vapor separator 98h of minimum size. Additionally, the above configuration has greater recirculation capability than a vapor separator that uses a single roller-vane type fuel pump while requiring less power from the electrical power source. 
     In the embodiments thus far described both the fuel and the oil are delivered to a single fuel tank; namely the vapor separator internal cavity. It is also possible, however, to deliver the fuel and oil to separate chambers. An embodiment of this invention provides an arrangement in which the oil is delivered to a second fuel tank where it is mixed with the fuel from the first fuel tank and filtered before being delivered to the fuel rail. The two tank arrangement permits the fuel pump to be removed without disturbing the first fuel tank. 
     FIGS. 20 and 21 illustrate a vapor separator 98j in which the Wesco-type fuel pump 138j is housed within the mounting plate 142j in front of the bowl 128j and connected thereto by a gusset 220. The mounting bracket 102j includes a concave arm portion 222 that receives the fuel pump 138j and to which a modified retainer 224 is affixed by means of the screw 226. A semicircular spacer 228 is interposed between the retainer 224 and the fuel pump 138j to hold the fuel pump 138j securely within the retainer 224 and arm portion 222 of the vapor separator mounting plate 142j. 
     The retainer 224 is provided with a pair of pressing members 228 along its upper surface which face each other and pressingly engage the upper surface of the fuel pump 138j and thus preclude motion of the fuel pump 138j along its vertical axis. 
     A second fuel tank or oil chamber is indicated generally by the reference numeral 230 and affixed to the lower portion of the mounting plate 142j immediately below the fuel pump 138j by any suitable means. The oil chamber 230 defines a cavity 232 which receives a supply of oil through the oil inlet port 154j which is formed integrally within the lower rear surface of the oil chamber 230. 
     An oil filter 234 engages the lower surface of the fuel pump 138j and extends through an opening in the oil chamber 230 into the cavity 232. An O-ring seal 236 is interposed between the lower surface of the fuel pump 138j and the upper surface of the oil chamber 230 so as to form a leak-proof barrier between the chamber 230 and fuel pump 138j. 
     A fuel influent port 238 is integrally formed within the oil chamber 230 adjacent to the oil inlet port 148j and opens to the cavity 232. The lower end of the port 238j is sealingly engaged by one end of a filtered fuel supply conduit 240. The second tank 230 can be easily disconnected from the first tank 130j by removing the end of the conduit 240 from the port 238j of the second tank 230. 
     The other end of the conduit 240 sealingly engages a fuel outlet port 242 that is integrally formed within the lower surface of the vapor separator bowl 128j. A fuel filtering element is indicated by the reference numeral 244 and extends completely across the lower portion of the bowl 128j above the port 242. 
     Thus, the fuel in the cavity 130j is filtered by the fuel filtering element 244 and delivered through the conduit 240 to the oil chamber cavity 232 where it mixes with the oil delivered to the cavity 232 through the oil inlet port 154j. The fuel and oil are drawn through the oil filter 234 where any impurities in the oil are filtered before being pumped by the fuel pump 138j to the fuel rail 104. 
     FIG. 22 shows in detail the manner by which the vapor separator 98j is affixed to the mounting bracket 102j. A pair of rubber grommets are indicated generally by the reference numeral 246 and extend through openings in the mounting plate 142j. Washer-type guides 248 are disposed within each of the grommets 246 through which the mounting bolts 100j extend to threadingly engage the mounting bracket 102j. Thus, with the above mounting system the vapor separator 98j is securely affixed to the engine 12 while the grommets 246 dampen any vibrations from the engine 12 to the vapor separator 98j and thus minimize the possibility of the fuel and oil foaming within the vapor separator 98j. 
     FIG. 23 illustrates a further vapor separator configuration that is indicated by the reference numeral 98k and is identical to the vapor separator 98j of FIGS. 20-22 except for the junction between the Wesco-type fuel pump 138k and the oil chamber 230k. In this embodiment, the bottom of the fuel pump 138k extends into the cavity 232k through the open upper end of the oil chamber 230k. The seal 236k is disposed from the oil chamber 230k and pressingly engages the lower end of the fuel pump 138k and prevents fuel and oil from leaking past the fuel pump 138k. 
     FIGS. 24 and 25 illustrate a further vapor separator configuration that is similar to the configurations illustrated in FIGS. 20-22 and FIG. 23 except that the manner by which the fuel pump 138l is affixed to the vapor separator 98l has been modified. In this embodiment, a fuel pump housing is indicated by the reference numeral 250 and formed integrally with the mounting plate 142l. An O-ring seal 252 is disposed within the lower portion of the housing 250 and pressingly engages the lower end of the fuel pump 138l above the oil filter 234l and thus seals the lower portion of the housing 250 which serves as the oil chamber 256 for the vapor separator 98l in which is disposed the oil filter 234l. 
     A cover is indicated by the reference numeral 258 and affixed to the open upper end of the fuel pump housing 250 by any suitable means. The cover 258 has openings formed along its upper surface through which the terminals 161l and the fuel outlet fitting 162l of the fuel pump 138l extends. An O-ring seal 260 is interposed between the cover 258 and upper end the fuel pump 138l and constrains the upper end of the fuel pump 138l within the cover 258. 
     From the foregoing, it should be readily apparent that the above-described vapor separators, respectively offer distinct advantages over prior art type of vapor separators. It provides a compact vapor separator with an improved sealing arrangement. And in some embodiment, the fuel pump can be easily removed for repair or service. 
     Although this invention has been described in terms of certain preferred embodiments, other embodiments apparent to those of ordinary skill in the art are also within the scope of this invention. Accordingly, the scope of the invention is intended to be defined only by the claims that follow.