Water cooled fuel reservoir for a carburetor of a marine propulsion device

Abstract

A water cooled fuel reservoir is provided for a carbureted engine. Water is drawn by a pump from a body of water and caused to flow to a water jacket surrounding a fuel reservoir of the carburetor. The fuel reservoir, or float bowl, stores a quantity of liquid fuel which is cooled by thermal contact with the water in a water jacket of the water reservoir.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally related to a fuel reservoir for a carburetor and, more particularly, to a fuel reservoir for a carburetor which is water cooled.

2. Description of the Related Art

Those skilled in the art of marine propulsion devices are familiar with many different types of cooling systems in which water from a body of water is directed in thermal communication with heat emitting components of a marine propulsion device. Those skilled in the art of engines having carburetors are familiar with the use of fuel reservoirs, or float bowls, which store a quantity of fuel for use by the carburetor. These reservoirs typically house a float device which regulates the flow of fuel into the reservoir as a function of the level of fuel in the reservoir. Those skilled in the art of marine propulsion devices are also familiar with a common problem that can occur as a result of elevated temperatures under the cowl of an outboard motor. These elevated temperatures can result in undesirable fuel vaporization and a condition that is sometimes referred to as “vapor lock”. Vapor lock can occur in marine propulsion engines, particularly after a prolonged period of operation and a shut down followed by a restart of the engine. In addition, operating an engine after a prolonged period of sustained operation when the components of the engine are at an elevated temperature can result in stalling of the engine. In addition, those skilled in the art of marine propulsion devices are also familiar with many different techniques used to control the temperature of engine components and liquid fuel.

U.S. Pat. No. 3,980,055, which issued to Webb on Sep. 14, 1976, describes a fuel saver and pollution control device. It includes a water reservoir, a heat exchanger for converting water from the water reservoir to steam, a conduit for conveying steam to a water trap in which steam from the heat exchanger is separated from liquid in the steam, a conduit for conveying steam from the water trap to the carburetor, a mixing chamber attached to the carburetor for mixing the steam with fuel, and a heat exchanger for heating fuel prior to the entry of fuel into the mixing chamber.

U.S. Pat. No. 3,845,745, which issued to Dunlap et al. on Nov. 5, 1974, describes a water injection system for an internal combustion engine. A pump is controlled by manifold pressure to provide water in the outlet lines when manifold pressure exceeds a predetermined magnitude and increasing amounts as the manifold pressure increases further. Water feed lines are connected to valving and nozzle means received within a spacer blade mounted to a carburetor such that the water is injected directly into the fuel air mixture and thereby supplied to all of the cylinders or rotary chambers.

U.S. Pat. No. 4,003,357, which issued to Furucz on Jan. 18, 1977, describes a carburetion system for internal combustion motors. It comprises a carburetor, a heat exchanger and an admission block. The carburetor has a carburetion chamber for each motor cylinder and is provided with a motor fuel reservoir. A primary circuit individually feeds each chamber from the reservoir while a secondary circuit, which is independent from the chambers, directly feeds the motor cylinders with an excess of motor fuel which is fed from the reservoir.

U.S. Pat. No. 4,155,337, which issued to Hensley on May 22, 1979, describes an internal combustion engine having a system for refrigerating fuel inducted into the carburetor. The spark ignited internal combustion engine has a carburetor and a mechanical refrigeration system improved with means for cooling the fuel inducted into the carburetor.

U.S. Pat. No. 4,424,789, which issued to Spalding on Jan. 10, 1984, describes a fuel line preheater. Improvements in fuel heating apparatus for internal combustion engines utilizes hot water from the engine cooling system as the heat exchanging medium.

U.S. Pat. No. 4,448,153, which issued to Miller on May 15, 1984, describes a water injection system for a combustion engine. It has an intake manifold and carburetor to which water is injected or sprayed by an electrically powered pump receiving water from a reservoir.

U.S. Pat. No. 4,915,063, which issued to Stumpf on Apr. 10, 1990, describes a vapor lock prevention system. It isolates the flow pump from the heat radiating engine block in a two cycle, air cooled engine and spaces the fuel pump from the carburetor and injects the fuel directly against the carburetor inlet valve. Application of an additional cooling means including air flow and liquid fuel means, may be provided in order to convey heat away from the fuel pump and therefore maintain the fuel pump temperature below the point at which vaporization pressure exceeds the impulse pressure generated from the power head. The fuel pump is removed from the hot carburetor as part of the vapor lock prevention system.

U.S. Pat. No. 6,474,317, which issued to Okuzawa et al. on Nov. 5, 2002, describes a heat exchange support plate for engine carburetors. The engine includes at least one combustion chamber formed by at least a first member and a second member that moves relative to the first member. The second member is coupled to an output shaft such that movement of the second member causes the output shaft to rotate. The engine also includes a cooling system configured to circulate coolant into thermal communication with at least a portion of the engine. An induction system is also included for providing a fuel/air charge to the combustion chamber. The induction system includes a charge former configured to form the fuel/air charge and a mounting plate that is attached to the carburetor. The mounting plate includes a first cooling passage that is in communication with the cooling system.

U.S. Pat. No. 6,718,954, which issued to Ryon on Apr. 13, 2004, describes an apparatus for cooling fuel and fuel delivery components. It uses a cold side of a thermal electric unit prior to entry of fuel into the fuel delivery components. An excess of cooling is supplied sufficient to cool the fuel delivery components so as to provide an additional buffer of cooling for the fuel and to prevent substantial re-absorption of heat after the fuel is cooled.

The patents described above are hereby expressly incorporated by reference in the description of the present invention.

In marine propulsion devices, such as outboard motors, heat can be transmitted from heat emitting components to a fuel storage reservoir, such as the float bowl of a carburetor. This heat can induce vaporization of liquid fuel and, as a result, adversely affect the metering of fuel flowing through the carburetor. If this characteristic is sufficiently affected by undesirable vaporization in the fuel reservoir, or float bowl, it can lead to engine stalling. This condition is particularly possible when the engine is operating at idle speed following a prolonged period of higher speed operation. Heat generated during the high speed operation continues to migrate to other components of the outboard motor after the end of the high speed operation and during the idling period. This heat can raise the temperature of fuel in the fuel bowl of a carburetor and cause fuel vaporization which, under certain circumstances, can sufficiently affect the fuel metering to the point that the engine is caused to stall.

SUMMARY OF THE INVENTION

A marine propulsion device having an engine and made in accordance with a preferred embodiment of the present invention, comprises a carburetor, a fuel reservoir configured to contain a volume of fuel for use by the carburetor, a water reservoir disposed in thermal communication with the fuel reservoir, a water pump configured to draw water from a body of water in which the marine propulsion device is operating, and an outlet conduit connected in fluid communication with the water reservoir. The water pump is connected in fluid communication with the water reservoir to direct water from the body of water into the water reservoir.

In a particularly preferred embodiment of the present invention, it further comprises a powerhead base configured to support the engine and to direct water to the water reservoir and to the engine. The water reservoir is configured to direct the water from the water reservoir back to the body of water through the outlet conduit. The water reservoir can comprise a water jacket substantially surrounding the fuel reservoir. Alternatively, it can comprise a water conduit disposed in thermal communication around the fuel reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully and completely understood from a reading of the description of the preferred embodiment in conjunction with the drawings, in which:

FIG. 1 is a highly schematic representation of a marine propulsion device showing the various components and the water flow between those components;

FIG. 2 is a schematic representation of a fuel reservoir;

FIG. 3 shows a water reservoir attached to the fuel reservoir of FIG. 2;

FIG. 4 is an isometric view of a carburetor, a fuel reservoir, and a water reservoir;

FIG. 5 shows the water reservoir and fuel reservoir illustrated in FIG. 4;

FIG. 6 is an exploded view of FIG. 5;

FIG. 7 is an exploded view of a more detailed illustration of the water reservoir and fuel reservoir of a preferred embodiment of the present invention;

FIG. 8 is an assembled view of the components illustrated in FIG. 7;

FIG. 9 is a section view of an alternative embodiment of the present invention;

FIG. 10 is a graphical representation of a test made with a conventional outboard motor fuel system; and

FIG. 11 is a test made with an outboard motor similar to the test illustrated in FIG. 10, but with the present invention used in conjunction with the fuel system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Throughout the description of the preferred embodiment of the present invention, like components will be identified by like reference numerals.

FIG. 1 is a highly schematic representation of a marine propulsion device, such as an outboard motor, and shows the circuit through which water travels. A pump 10 is disposed below a level of water 12 in many types of outboard motor configurations. The water is caused to flow upward, as represented by arrow 16, through a powerhead base 18 which can be an adapter plate. The primary function of the powerhead base 18 is to support the cylinder block 20. Another important function of the powerhead base 18 is to direct water flowing from the pump 10 to the cylinder block 20, as indicated by arrow 24, and to a carburetor 30, as represented by arrow 32. The carburetor 30 in FIG. 1 is shown schematically with a water jacket 40 substantially surrounding the carburetor structure. It should be understood that the carburetor 30 is shown schematically in FIG. 1 and actually represents a carburetor and an associated fuel reservoir, or float bowl. This will be shown in greater detail below. After passing through the water jacket 40 of the carburetor float bowl, water is directed back toward the body of water 12 as represented by arrow 42.

With continued reference to FIG. 1, water flowing to the cylinder block 20 from the powerhead base 18, as represented by arrow 24, is controlled by a thermostat 50. This operation is well known to those skilled in the art and will not be described in detail herein. After water flows in thermal communication with the cylinder block 20, it is directed through an exhaust system 60 of the marine propulsion device as represented by arrow 62. From there it is returned to the body of water 12.

FIG. 2 is a simplified representation of a fuel reservoir 100 of a carburetor. Although not shown in FIG. 2, it should be understood that the reservoir 100 would contain a quantity of liquid fuel for use by the carburetor and a float which is functionally attached to the carburetor and located within the cavity of the reservoir 100. The float, in a manner well understood by those skilled in the art, controls the flow of fuel into the reservoir 100 as a function of the fuel level within the reservoir, or float bowl.

FIG. 3 shows the fuel reservoir 100 associated with a water reservoir 110. These two components shown in FIG. 3 are configured to be combined together to define the water jacket 40 as illustrated. An inlet 112 and an outlet 114 are provided to direct water into and through the water jacket 40. It can be seen that the water within the water jacket 40 generally surrounds the fuel within the fuel reservoir 100.

With reference to FIGS. 4-6, a carburetor 130 is shown attached to a water reservoir 110 and a fuel reservoir 100. As described above in conjunction with the simplified illustrations of FIGS. 2 and 3, the fuel reservoir 100 is disposed within the water reservoir 110 to define a water jacket 40 therebetween. It should also be understood that FIGS. 2 and 3 are highly simplified schematic representations to show the functions of the fuel reservoir 100 and the water reservoir 110 and how a simplified version of this structure can be used to define the water jacket 40. The illustrations shown in FIGS. 4-6 show a particularly preferred embodiment of that basic structure. The outer housing of the water reservoir 110 is shown in FIG. 6 exploded away from the fuel reservoir 100. The inlet 112 and outlet 114 are in slightly different positions than the positions illustrated in FIG. 3. Water flows within the water reservoir 110 surrounding the outer surfaces of the fuel reservoir 100 when these components are attached together as shown in FIG. 5.

FIGS. 7 and 8 show section views of the preferred embodiment of the present invention described above in conjunction with FIGS. 4-6. The illustrations in FIGS. 7 and 8 are functionally similar to the illustrations in FIGS. 2 and 3, but are directed to a particular preferred embodiment of the present invention and not to the general functional representation of FIGS. 2 and 3.

The fuel reservoir 100 has a lower section 140. The water reservoir 110 is provided with an opening 142 that is shaped to receive the lower portion 140 of the fuel reservoir 100 and allow access to that lower portion from a position below the water reservoir 110. The lower portion 140 is primarily intended to provide a fuel drain access for the fuel reservoir 100. FIG. 8 illustrates the fuel reservoir 100 disposed within the water reservoir 110, defining the water jacket 40, and also showing the lower portion 140 of the fuel reservoir 100 extending downwardly through the opening 142.

FIG. 9 shows an alternative embodiment of the present invention in which the water jacket 40 is provided by attaching a conduit 180, which serves as the water reservoir 110, in thermal communication with the fuel reservoir 100. As water is introduced into the inlet 112, it flows through the conduit 180 around the fuel reservoir 100, in a spiral path, and leaves the water jacket 40 through outlet 114.

FIGS. 10 and 11 are graphical representations of actual empirical testing of a system that is generally similar to the system shown in FIGS. 2 and 3. Engine speed is represented by line 200 in FIG. 10. As can be seen, at approximately 200 seconds from the beginning of the test, the engine speed is increased from an idle speed, below 1500 RPM, to an operating speed of approximately 5500 RPM. Dashed line 202 represents the ambient temperature surrounding the marine propulsion device during the test. Dashed line 204 represents the air intake temperature under the cowl of the outboard motor. Dashed line 206 represents the temperature of the surface of the air intake manifold of the engine, and dashed line 208 represents the temperature of the fuel flowing into the fuel reservoir. Dashed line 210 represents the temperature of the fuel within the float bowl, or fuel reservoir, of the carburetor.

With continued reference to FIG. 10, it can be seen that with the increase in RPM at approximately 200 seconds, dashed lines 206 and 208 temporarily decrease in temperature and then increase during the period of time when the engine is operating at approximately 5500 RPM. Similarly, dashed line 210, which represents the temperature of the fuel within the float bowl or fuel reservoir increases during the time of high RPM running. This continues throughout the duration of increased engine speed, from approximately 200 seconds to approximately 1300 seconds. After the engine is slowed to idle speed again at approximately 1300 seconds, the fuel temperature within the fuel reservoir, represented by dashed line 210, continues to increase. This is a result of heat being transferred from heat emitting components to the carburetor and its float bowl. This increases the temperature of the fuel within the float bowl and, under certain conditions, induces its vaporization. This, in turn, can adversely affect the fuel metering capability of the carburetor. Under certain adverse conditions, this can lead to the stalling of the engine. The primary intent of the present invention is to reduce the temperature of the fuel within the float bowl, represented by dashed line 210, during and after periods of increased engine speed, such as the period between 200 seconds and 1300 seconds in FIG. 10.

FIG. 11 is a graphical representation of a test made with an engine incorporating the present invention. As can be seen, line 200 in FIG. 11 is generally similar to line 200 in FIG. 10, indicating that the engine speed profile during the test between times 200 seconds and 1300 seconds is generally identical to that used for the test illustrated graphically in FIG. 10. Similarly, the undercowl intake air temperature 204 is similar to that shown in FIG. 10. Although the absolute magnitudes of temperature represented by dashed lines 206 and 208 are slightly different than those represented by dashed lines 206 and 208 in FIG. 10, their overall change in behavior are generally similar to those represented in the test illustrated in FIG. 10. Similarly, the room temperature 202 is similar to that illustrated in FIG. 10 and described above. However, the fuel temperature 210 within the carburetor fuel reservoir behaves significantly differently when the present invention is used in FIG. 11 as compared to when the present invention is not used in FIG. 10. The flow of water through the water jacket 40, described above in conjunction with FIGS. 2, 3, 7 and 8 prevent the fuel temperature from rising by the same magnitude it does in FIG. 10 between times 200 seconds and 1300 seconds. Therefore, during high engine speed, the flow of water maintains the fuel temperature in the float bowl at a significantly lower temperature and when the present invention is not used. In addition, immediately after the engine speed is reduced back to idle, at approximately 1300 seconds, the temperature of the fuel within the fuel reservoir actually decreases as compared to the continued increase illustrated by dashed line 210 in FIG. 10 after the engine speed is reduced to idle speed.

With continued reference to FIGS. 10 and 11, it should be understood that the water pump 10, described above in conjunction with FIG. 1, is typically driven by the crankshaft of the engine. Therefore, when the engine speed increases, the pump speed also increases. In addition, after the engine speed is again reduced to idle speed, the pump continues to induce the flow of water through the water jacket 40, but at a lower speed which is typically controlled by the crankshaft speed. As long as the engine is operating, at any speed, the water pump 10 is operating. Therefore, even at idle speed, water is being circulated through the water jacket 40 to remove heat from the fuel reservoir 100 and the liquid fuel contained therein. Therefore, the fuel is maintained at an efficient operating temperature and fuel vaporization is significantly inhibited. When the engine is off, the water within the water reservoir 110 continues to absorb heat from the fuel reservoir 100.

The marine propulsion device incorporating the present invention comprises a carburetor. Those skilled in the art of engines and, more particularly, marine propulsion engines, are familiar with the significant differences between carbureted engines and engines which utilize fuel injectors. Fuel injection systems often use a reservoir referred to as a fuel vapor separator. Fuel vapor separators serve a significantly different function than float bowls or fuel reservoirs for carburetors. Typically, fuel vapor separators incorporate fuel pumps to raise the pressure of the fuel from the reservoir to the injector. Carburetors do not incorporate pumps of this kind. In addition, fuel vapor separators are vented to allow the separation of fuel vapor from liquid fuel. Fuel reservoirs, or float bowls, of carbureted systems are not intended to perform this function. Those skilled in the art of fuel injection systems are aware that water cooling can be used to reduce the temperature of a fuel vapor separator. However, carbureted engines have not been cooled with water jackets associated with their float bowls, or fuel reservoirs.

With reference to FIGS. 1-11, it can be seen that a marine propulsion device made in accordance with a preferred embodiment of the present invention comprises a carburetor 130, a fuel reservoir 100 configured to contain a volume of fuel for use by the carburetor 130, a water reservoir 110 disposed in thermal communication with the fuel reservoir 100, and a water pump 10 configured to draw water from a body of water 12 in which the marine propulsion device is operating. The water pump 10 is connected in fluid communication with the water reservoir 110 to direct water from the body of water 12 into the water reservoir 110. In addition, the present invention comprises an outlet conduit 114 which is connected in fluid communication with the water reservoir. A powerhead base 32 is configured to support the engine 20 and to direct water to the water reservoir 110 and to the engine 20. The water reservoir 110 is configured to direct the water from the water reservoir, or water jacket 40, back to the body of water 12. The water reservoir 110 can comprise a water jacket 40 substantially surrounding the fuel reservoir 100. Alternatively, the water reservoir 110 can comprise a water conduit 180 disposed around the fuel reservoir 100.

Although the present invention has been described in particular detail and illustrated to show various alternative embodiments of the present invention, it should be understood that alternative embodiments are also within its scope.

Claims

1. A marine propulsion device having an engine, comprising:

a carburetor;

a fuel reservoir configured to contain a volume of fuel for use by said carburetor;

a water reservoir disposed in thermal communication with said fuel, said water reservoir comprising a water jacket substantially surrounding said fuel reservoir;

a water pump configured to draw water from a body of water in which said marine propulsion device is operating, said water pump being connected in fluid communication with said water reservoir to direct said water from said body of water into said water reservoir; and

an outlet conduit connected in fluid communication with said water reservoir.

2. The marine propulsion device of claim 1, further comprising:

a powerhead base configured to support said engine and to direct said water to said water reservoir and to said engine.

3. The marine propulsion device of claim 1, wherein:

said water reservoir is configured to direct said water from said water reservoir back to said body of water.

4. (canceled)

5. The marine propulsion device of claim 1, wherein:

said water reservoir comprises a water conduit disposed around said fuel reservoir.

6. A marine propulsion device having an engine, comprising:

a carburetor;

a fuel reservoir configured to contain a volume of fuel for use by said carburetor;

a water reservoir disposed in thermal communication with said fuel reservoir, said water reservoir comprising a water jacket substantially surrounding said fuel reservoir;

a water pump configured to draw water from a body of water in which said marine propulsion device is operating, said water pump being connected in fluid communication with said water reservoir to direct said water from said body of water into said water reservoir;

a powerhead base configured to support said engine; and

an outlet conduit connected in fluid communication with said water reservoir.

7. The marine propulsion device of claim 6, wherein:

said powerhead base is configured to direct said water to said water reservoir and to said engine.

8. The marine propulsion device of claim 7, wherein:

said powerhead base is an adapter plate.

9. The marine propulsion device of claim 6, wherein:

said water reservoir is configured to direct said water from said water reservoir back to said body of water.

10. (canceled)

11. The marine propulsion device of claim 6, wherein:

said water reservoir comprises a water conduit disposed around said fuel reservoir.

12. A marine propulsion device having an engine, comprising:

a carburetor;

a fuel reservoir configured to contain a volume of fuel for use by said carburetor;

a water reservoir disposed in thermal communication with said fuel reservoir, said water reservoir comprising a water jacket substantially surrounding said fuel reservoir;

a water pump configured to draw water from a body of water in which said marine propulsion device is operating, said water pump being connected in fluid communication with said water reservoir to direct said water from said body of water into said water reservoir;

an outlet conduit connected in fluid communication with said water reservoir; and

a powerhead base configured to support said engine and to direct said water to said water reservoir and to said engine.

13. The marine propulsion device of claim 12, wherein:

said marine propulsion device is an outboard motor.

14. The marine propulsion device of claim 13, wherein:

said water reservoir is configured to direct said water from said water reservoir back to said body of water.

15. (canceled)

16. The marine propulsion device of claim 14, wherein:

said water reservoir comprises a water conduit disposed around said fuel reservoir.