1. Field of the Invention
The present invention relates to a fuel supply system for a boat and an outboard motor. Specifically, the present invention relates to a fuel supply system for a boat having a second fuel tank connected to a first fuel tank mounted on a hull and an outboard motor.
2. Description of the Related Art
Conventionally, a fuel supply system for a boat having a second fuel tank connected to a first fuel tank mounted on a hull is known (See JP A 2001-140720 and JP A Hei 9-88623, for example).
The fuel supply system for a boat described in JP A 2001-140720 and JP A Hei 9-88623 is a fuel supply system for a boat having an outboard motor. In examples disclosed in JP A 2001-140720 and JP A Hei 9-88623, fuel pumped from a fuel tank (first fuel tank) mounted on a hull is contained in a vapor separator tank (second fuel tank). The fuel contained in the vapor separator tank is supplied to a fuel injection device by a fuel supply pump. The vapor separator tank is disposed close to an engine.
However, in the examples disclosed in JP A 2001-140720 and JP A Hei 9-88623, since the vapor separator tank is disposed close to the engine, it is subject to heat radiated from the engine. Therefore, when the engine of a boat is stopped after a heavily-loaded operation, the fuel temperature in the vapor separator tank is increased by heat radiated from the heated engine. Accordingly, the fuel in the vapor separator tank easily becomes vapor (vaporized fuel) and then returns to the fuel tank mounted on the hull. In this case, fuel in the vapor separator tank decreases due to the vaporized fuel that is returned to the fuel tank mounted on the hull. Therefore, during a restart of the engine, it takes a long time to pump up fuel to the vapor separator tank from the fuel tank on the hull, which makes it difficult for the fuel supply pump to efficiently pump up fuel from the vapor separator tank to supply to the fuel injection device. This hampers smooth engine starting.
In order to overcome the problems described above, preferred embodiments of the present invention provide a fuel supply system for a boat and an outboard motor that minimizes deterioration in engine startability.
A fuel supply system for a boat according to a first preferred embodiment of the present invention includes a second fuel tank arranged to be connected to a first fuel tank mounted on a hull of a boat, the second fuel tank arranged to contain fuel therein; a fuel injection device arranged to supply fuel to an engine; a fuel supply pump arranged to supply the fuel contained in the second tank to the fuel injection device; and a throttle body including a throttle valve arranged to adjust a flow rate of air to the engine. The second fuel tank is disposed adjacent to the throttle body. Note that the word “adjacent to” means not only the case where the second fuel tank contacts with the throttle body but also the case where there is a gap between the second fuel tank and the throttle body or the case where there is another member between the second fuel tank and the throttle body.
In the fuel supply system for a boat according to the first preferred embodiment, as described above, the second fuel tank is disposed adjacent to the throttle body including the throttle valve arranged to adjust a flow rate of air to the engine. Therefore, the second fuel tank receiving heat radiated from the engine can be cooled by the throttle body which has a relatively low temperature. More specifically, since air flows fastest in the throttle body, heat is rapidly absorbed by the fast flowing air or by the fuel vaporization. As a result, the throttle body becomes resistant to a rise in temperature. The second fuel tank receiving heat radiated from the engine can be cooled by the throttle body which has a relatively low temperature disposed adjacent to the second fuel tank. This minimizes an increase in the temperature in the second fuel tank, thereby minimizing the generation of vapor (vaporized fuel) in the second fuel tank. Therefore, it is possible to prevent vaporized fuel from returning to the first fuel tank mounted on the hull, thereby minimizing the fuel reduction in the second fuel tank. As a result, it becomes easy for the fuel supply pump to pump fuel up from the second fuel tank and supply fuel to the fuel injection device during a restart of the engine. Deterioration in startability of the engine can thereby be minimized.
In the fuel supply system for a boat according to the first preferred embodiment, the second fuel tank and the throttle body are preferably integral, or separate but disposed adjacent to each other.
In the fuel supply system for a boat according to the first preferred embodiment, the second fuel tank and the fuel supply pump are preferably spaced away from the engine. With this configuration, since the second fuel tank and the fuel supply pump are not directly attached to the engine, heat directly transmitted from the engine to the second fuel tank and the fuel supply pump can be minimized. Thus, a temperature increase in the second fuel tank and the fuel supply pump can be minimized, thereby minimizing the generation of vapor in the second fuel tank and the fuel supply pump.
Preferably, the fuel supply system for a boat according to the first preferred embodiment further includes a check valve arranged to allow the vaporized fuel in the second fuel tank to pass in a direction from the second fuel tank to the throttle body. With this configuration, when vaporized fuel collects in the second fuel tank, the pressure of the vaporized fuel opens the check valve to automatically release the vaporized fuel in the second fuel tank to the throttle body.
In the fuel supply system for a boat according to the first preferred embodiment, the fuel supply pump is preferably disposed outside and adjacent to the second fuel tank. With this configuration, a pipe arranged to connect the fuel supply pump and the second fuel tank can be shortened, thereby decreasing a heat receiving area that receives heat radiated from the engine. This minimizes the generation of vaporized fuel.
In this case, preferably, the second fuel tank is disposed below and adjacent to the throttle body and the fuel supply pump is disposed beside and adjacent to the second fuel tank. With this configuration, the throttle body, the second fuel tank, and the fuel supply pump can be arranged within a small space.
In the above configuration where the second fuel tank is disposed below the throttle body and the fuel supply pump is disposed beside the second fuel tank, preferably, the second fuel tank is placed on one side with respect to a vertical center line crossing a central axis of an air passage of the throttle body and the fuel supply pump is placed on the other side with respect to the vertical center line. With this configuration, the second fuel tank and the fuel supply pump can be arranged so that they sandwich the air passage of the throttle body. Thus, a unit defined by the throttle body, the second fuel tank, and the fuel supply pump can be made compact.
In the above configuration where the second fuel tank is disposed below the throttle body and the fuel supply pump is disposed beside the second fuel tank, preferably, the fuel supply pump includes a pump main portion having a fuel path, a rotary shaft arranged to drive the pump main portion, and a pump driving section arranged to rotate the rotary shaft, and the pump main portion is disposed below the throttle body and beside and adjacent to the second fuel tank. With this configuration, since the pump main portion is disposed beside and adjacent to the second fuel tank, a fuel pipe arranged to connect the pump main portion and the second fuel tank can be prevented from being lengthened.
In this case, preferably, the rotary shaft extends upward from the pump main portion and is positioned out of the air passage of the throttle body as seen from the top, and a bearing portion is preferably integral with the throttle body in the vicinity of the air passage of the throttle body to retain the rotary shaft to be rotatable. With this configuration, the rotary shaft can be extended upward via the bearing portion provided in the vicinity of the air passage of the throttle body. This allows the pump main portion to be positioned in the vicinity of the air passage of the throttle body, thereby bringing the pump main portion closer to the second fuel tank. Accordingly, the fuel pipe arranged to connect the pump main portion and the second fuel tank can be further prevented from being lengthened.
In the above configuration where the fuel supply pump is disposed outside of and adjacent to the second fuel tank, the fuel injection device is preferably configured to be disposed adjacent to the throttle body and to inject fuel in the throttle body. With this configuration, all of the fuel supply pump, the second fuel tank, and the fuel injection device can be disposed adjacent to the vicinity of the throttle body. This allows the fuel system to be arranged within a small space, thereby shortening pipes arranged to connect the second fuel tank, the fuel supply pump, and the fuel injection device with each other. This decreases a heat-receiving area that receives heat radiated from the engine, thereby minimizing the generation of vaporized fuel. Also, since the fuel system is disposed within a small space, the fuel supply system for a boat can be made compact.
In this case, preferably, the engine includes a plurality of cylinders and further includes a plurality of intake pipes, first ends of which are connected to the throttle body and second ends of which are respectively connected to the plurality of cylinders, and a single fuel injection device is provided for all of the plurality of intake pipes. With this configuration, the single fuel injection device can supply a fuel-air mixture to the plurality of cylinders.
In the fuel supply system for a boat according to the first preferred embodiment, the second fuel tank, the fuel injection device, and the fuel supply pump are preferably supported by the throttle body. With this configuration, the fuel system including the second fuel tank, the fuel supply pump, and the fuel injection device is not directly supported by the heated engine. Accordingly, differing from the case where the fuel system is supported by the engine via supporting members, a temperature rise of the fuel system caused by heat directly transmitted from the engine can be minimized.
In the fuel supply system for a boat according to the first preferred embodiment, at least one of a throttle opening sensor arranged to detect the opening degree of the throttle valve, an intake air temperature sensor arranged to detect air temperature in the throttle body, an intake air pressure sensor arranged to detect air pressure in the throttle body, and an Idle Speed Control unit may be disposed adjacent to the throttle body.
An outboard motor according to a second preferred embodiment of the present invention includes an engine; a second fuel tank arranged to be connected to a first fuel tank mounted on a hull, the second fuel tank arranged to contain fuel therein; a fuel injection device arranged to supply fuel to the engine; a fuel supply pump arranged to supply the fuel contained in the second tank to the fuel injection device; and a throttle body including a throttle valve arranged to adjust a flow rate of air to the engine, wherein the second fuel tank is disposed adjacent to the throttle body.
In the outboard motor according to the second preferred embodiment, as described above, the second fuel tank is disposed adjacent to the throttle body including the throttle valve arranged to adjust a flow rate of air to the engine. Therefore, the second fuel tank receiving heat radiated from the engine can be cooled by the throttle body which has a relatively low temperature. More specifically, air flows fastest in the throttle body, rapidly drawing heat from the throttle body. As a result, the throttle body becomes resistant to a rise in temperature. The second fuel tank receiving heat radiated from the engine can be cooled by the throttle body which has a relatively low temperature disposed adjacent to the second fuel tank. This minimizes an increase in the temperature in the second fuel tank, thereby minimizing the generation of vapor (vaporized fuel) in the second fuel tank. Therefore, it is possible to prevent vaporized fuel from returning to the first fuel tank mounted on the hull, thereby minimizing the fuel reduction in the second fuel tank. As a result, it becomes easy for the fuel supply pump to pump fuel up from the second fuel tank and supply fuel to the fuel injection device during a restart of the engine. Deterioration in startability of the engine can thereby be minimized.
Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.
Preferred embodiments of the present invention are described below with reference to the accompanying drawings.
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The fuel sent out by the low-pressure fuel pump 43 via the fuel pipe 44 is discharged from an outlet 45a (see
The vapor separator tank 45 contains the fuel pumped up from the fuel tank 102 and separates the vaporized fuel (vapor) or air from the liquid fuel. As shown in
At the bottom of the vapor separator tank 45, there is provided a water sensor 45e arranged to detect water collected at the bottom of the vapor separator tank 45. Specifically, a central portion 45f of the bottom of the vapor separator tank 45 protrudes upward. The protruded portion defines a recess as seen from the outside below the vapor separator tank 45. Two leads 451, 452 are disposed in the recess and tips of the leads 451, 452 are connected. Also, a pair of floats 45g that are floatable in water are provided at the bottom of the vapor separator tank 45. Each of the pair of floats 45g has a built-in magnet (not shown). When water is collected in the bottom of the vapor separator tank 45, the float 45g having a magnet rises as a water level “Q” rises. When the floats 45g rise up to a predetermined position, the tip of the lead 451 and the tip of the lead 452 are separated from each other by magnetic forces from the magnets. Accordingly, the connection between the leads 451, 452 is interrupted. With the above configured water sensor 45e, it is possible to detect whether or not an amount of water that is collected equal to or more than a predetermined quantity in the bottom of the vapor separator tank 45.
A leading end 46h of a pipe 46f is inserted into an upper portion of the vapor separator tank 45. The pipe 46f is connected to the high-pressure fuel pump 46, which will be described below. The fuel returned from the high-pressure fuel pump 46 is discharged from the leading end 46h of the pipe 46f into the vapor separator tank 45. A buffer plate 45h is disposed below the leading end 46h of the pipe 46f and above the float 45c in the vapor separator tank 45. A plurality of small holes are provided in the buffer plate 45h. Fuel is discharged from the leading end 46h of the pipe 46f via the holes of the buffer plate 45h into the vapor separator tank 45 to be contained therein again. When the fuel discharged from the leading end 46h of the pipe 46f bubbles, the buffer plate 45h can drip the liquid fuel into the vapor separator tank 45 without dropping bubbles.
A check valve 45i is provided in a communication passage between the vapor separator tank 45 and the throttle body 32. The check valve 45i is configured to pass vapor (vaporized fuel) or air only in one direction from the vapor separator tank 45 to the throttle body 32. When vapor occurs to increase an internal pressure of the vapor separator tank 45, the check valve 45i opens to discharge the vapor from the vapor separator tank 45 to the throttle body 32. Also, when the engine (engine section 2) is operated, the negative pressure in the throttle body 32 opens the check valve 45i to discharge the vapor from the vapor separator tank 45 to the throttle body 32.
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In this preferred embodiment, as described above, the vapor separator tank 45 is disposed adjacent to the throttle body 32 including the throttle valve 32b. Accordingly, the vapor separator tank 45 that receives heat radiated from the engine 20 can be cooled by the throttle body 32 having a relatively low temperature. More specifically, air flows fastest in the throttle body 32, rapidly drawing heat from the throttle body 32. As a result, the throttle body 32 becomes resistant to an increase in temperature. Being disposed adjacent to the vapor separator tank 45, the throttle body 32 has a relatively low temperature which can cool the vapor separator tank 45 that receives heat radiated from the engine 20. This minimizes an increase in the temperature in the vapor separator tank 45, thereby minimizing the generation of vapor (vaporized fuel) in the vapor separator tank 45. Therefore, it is possible to prevent fuel from returning to the fuel tank 102 mounted on the hull, thereby minimizing the fuel reduction in the vapor separator tank 45. As a result, it becomes easy for the high-pressure fuel pump 46 to pump fuel up from the vapor separator tank 45 and supply fuel to the injector 47 during a restart of the engine section 2. Deterioration in startability of the engine section 2 can thereby be minimized.
In this preferred embodiment, as described above, the vapor separator tank 45 and the high-pressure fuel pump 46 are spaced away from the engine 20. That is, the vapor separator tank 45 and the high-pressure fuel pump 46 are not directly attached to the engine 20. This minimizes direct heat transmission from the engine 20 to the vapor separator tank 45 and the high-pressure fuel pump 46. Thus, a temperature increase in the vapor separator tank 45 and the high-pressure fuel pump 46 can be minimized, thereby minimizing the generation of vapor in the vapor separator tank 45 and the high-pressure fuel pump 46.
In this preferred embodiment, as described above, the vapor separator tank 45 and the throttle body 32 are preferably fixed by screws 200, for example, so as to be adjacent to and contact with each other.
In this preferred embodiment, as described above, the check valve 45i is arranged to allow the vaporized fuel in the vapor separator tank 45 to pass only in a direction from the vapor separator tank 45 to the throttle body 32. When vaporized fuel collects in the vapor separator tank 45, the check valve 45i is opened by the pressure of the vaporized fuel to automatically release the vaporized fuel in the vapor separator tank 45 to the throttle body 32. In this preferred embodiment, the vapor separator tank 45 and the throttle body 32 are disposed adjacent to each other so as to contact each other. Therefore, the vaporized fuel in the vapor separator tank 45 can be released without utilizing an extra pipe for connecting the vapor separator tank 45 and the throttle body 32 as in the case where the vapor separator tank 45 and the throttle body 32 are separated from each other.
In this preferred embodiment, as described above, the high-pressure fuel pump 46 is preferably disposed outside of and adjacent to the vapor separator tank 45. Therefore, the pipes 46e, 46f arranged to connect the high-pressure fuel pump 46 and the vapor separator tank 45 can be shortened, thereby decreasing a heat-receiving area that receives heat radiated from the engine 20. This minimizes the generation of vaporized fuel.
In this preferred embodiment, as described above, the vapor separator tank 45 is disposed below and adjacent to the throttle body 32 and the high-pressure fuel pump 46 is disposed beside and adjacent to the vapor separator tank 45. With this configuration, the throttle body 32, the vapor separator tank 45, and the high-pressure fuel pump 46 can be arranged within a small space.
In this preferred embodiment, as described above, the vapor separator tank 45 is placed on one side across the center line “O” crossing the central axis of the air passage 32a of the throttle body 32, while the high-pressure fuel pump 46 is placed on the other side, so that the air passage 32a of the throttle body 32 is sandwiched between the vapor separator tank 45 and the high-pressure fuel pump 46. Thus, a unit constructed with the throttle body 32, the vapor separator tank 45, and the high-pressure fuel pump 46 can be made compact.
In this preferred embodiment, as described above, the pump main portion 46a is disposed below the throttle body 32 and disposed beside and adjacent to the vapor separator tank 45. Since the pump main portion 46a is disposed beside and adjacent to the vapor separator tank 45, the pipe 46e arranged to connect the pump main portion 46a and the vapor separator tank 45 can be prevented from being lengthened.
In this preferred embodiment, as described above, the bearing portion 32k is preferably integral with the throttle body 32 in the vicinity of the air passage 32a of the throttle body 32 to retain the rotary shaft 46c to be rotatable. Therefore, the rotary shaft 46c can be extended above the throttle body 32 via the bearing portion 32k located in the vicinity of the air passage 32a of the throttle body 32. Thus, the pump main portion 46a is disposed in the vicinity of the air passage 32a of the throttle body 32, which makes it possible to bring the pump main portion 46a close to the vapor separator tank 45. Therefore, the pipe 46e arranged to connect the pump main portion 46a and the vapor separator tank 45 can be further prevented from being lengthened.
In this preferred embodiment, as described above, the injector 47 is disposed adjacent to the throttle body 32 and configured to inject fuel in the throttle body 32. Thus, all of the vapor separator tank 45, the high-pressure fuel pump 46, and the injector 47 can be disposed in the vicinity of the throttle body 32. Since the fuel system 40 is thus disposed within a small space, the pipes 46e, 46f, 46g arranged to connect the vapor separator tank 45, the high-pressure fuel pump 46, and the injector 47 can be shortened. This decreases a heat-receiving area that receives heat radiated from the engine 20, thereby minimizing the generation of vapor (vaporized fuel). Since the fuel system 40 is disposed within a small space, the outboard motor 1 can be made compact.
In this preferred embodiment, as described above, fuel is injected in the throttle body 32. Thus, the single injector 47 can supply fuel-air mixture to the two cylinders 21.
In this preferred embodiment, the vapor separator tank 45, the high-pressure fuel pump 46, and the injector 47 are supported by the throttle body 32, and therefore the fuel system 40 including the vapor separator tank 45, the high-pressure fuel pump 46, and the injector 47 is not directly supported by the heated engine 20. Therefore, differing from the case where the fuel system 40 is supported by the engine 20 via supporting members, it is possible, in this preferred embodiment, to minimize an increase in the temperature of the fuel system 40 caused by heat directly transmitted from the engine 20 via the supporting members and the like.
In this preferred embodiment, the throttle body 32, the vapor separator tank 45, and the high-pressure fuel pump 46 are disposed adjacent to each other to be fixed together, thereby defining a unit. Therefore, the throttle body 32, the vapor separator tank 45, and the high-pressure fuel pump 46 are assembled as one unit and the assembled unit can be attached to the intake system 30. This improves the ease of assembling of the outboard motor 1.
It should be understood that the preferred embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is intended to be defined not by the above description of the preferred embodiments but by the claims, and to include all equivalents and modifications of the claims.
For example, in the above preferred embodiments, the vapor separator tank 45 is disposed below and adjacent to the throttle body 32. However, the present invention is not limited thereto. The vapor separator tank 45 may be disposed beside and adjacent to the throttle body 32.
In the above preferred embodiments, the vapor separator tank 45 and the throttle body 32 are preferably fixed by the screws 200, for example. However, the present invention is not limited thereto. The vapor separator tank 45 and the throttle body 32 may be integrally made of resin, for example.
In the above preferred embodiments, the vapor separator tank 45 and the outer frame 46b of the high-pressure fuel pump 46 are preferably fixed by the screws 201, for example. However, the present invention is not limited thereto. The vapor separator tank 45 and the outer frame 46b of the high-pressure fuel pump 46 may be integrally made of resin, for example.
In the above preferred embodiments, the pulley 46d fixed to the rotary shaft 46c of the high-pressure fuel pump 46 is preferably meshed with the belt 26 for driving the camshaft 27 to drive the high-pressure fuel pump 46 using the driving force of the engine 20. However, the present invention is not limited to this example. As in a high-pressure fuel pump 300 according to a first variation shown in
In the above preferred embodiments, the rotary shaft 46c of the high-pressure fuel pump 46 is preferably rotated by the pulley 46d and the belt 26. However, the present invention is not limited thereto. The rotary shaft 46c may be rotated by transmitting rotation of the camshaft 27 to the rotary shaft 46c of the high-pressure fuel pump 46 using gears and the like.
In the above preferred embodiments, the high-pressure fuel pump 46 transports fuel by driving the plunger 463 with the swash plate 462. However, the present invention is not limited thereto. Other types of high-pressure fuel pumps such as a vane-type pump, a screw-type pump or a trochoid-type pump may be used.
In the above preferred embodiments, an in-line type fuel pump in which the high-pressure fuel pump 46 is disposed outside the vapor separator tank 45 is preferably used. However, the present invention is not limited thereto. The high-pressure fuel pump 46 may be disposed inside the vapor separator tank 45
In the above preferred embodiments, the fuel preferably is gasoline. However, the present invention is not limited thereto. The fuel may be alcohol.
In the above preferred embodiments, the fuel supply system for a boat of the present invention is preferably applied to the outboard motor 1. However, the present invention is not limited thereto. The fuel supply system may be applied to an inboard motor in which an engine section is mounted on a hull or to an inboard/outboard motor.
In the above preferred embodiments, the throttle body 32 is preferably configured to contact the vapor separator tank 45. However, the present invention is not limited thereto. A gap or another member may be provided between the throttle body 32 and the vapor separator tank 45.
In the above preferred embodiments, the high-pressure fuel pump 46 and the vapor separator tank 45 are preferably supported by the throttle body 32 of the intake system 30. However, the present invention is not limited thereto. The high-pressure fuel pump 46 and the vapor separator tank 45 may be supported by another component. For example, the high-pressure fuel pump 46 and the vapor separator tank 45 may be supported by such a component as a bracket fixed to the engine.
In the above preferred embodiments, the present invention is applied to the outboard motor 1 preferably utilizing the two-cylinder engine section 2 having the two cylinders 21. However, the present invention is not limited thereto. The present invention may be applied to an outboard motor utilizing an engine section having one cylinder or three or more cylinders. For example, a three-cylinder engine section 2a according to a second variation shown in
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
Number | Date | Country | Kind |
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2008-142575 | May 2008 | JP | national |
Number | Name | Date | Kind |
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5115784 | Mito et al. | May 1992 | A |
5555858 | Katoh | Sep 1996 | A |
5829402 | Takahashi et al. | Nov 1998 | A |
5896835 | Kato | Apr 1999 | A |
6695657 | Hattori | Feb 2004 | B2 |
Number | Date | Country |
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09-088623 | Mar 1997 | JP |
2001-140720 | May 2001 | JP |
Number | Date | Country | |
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20090298365 A1 | Dec 2009 | US |