Abstract:
A fuel supply system of an outboard motor for supplying a fuel stored in a fuel tank to an intake port of an engine includes: a vapor separator which is disposed on one of left and right sides of the engine in terms of a traveling direction of a hull and to whose upper portion a vapor vent pipe having a tip open to an atmosphere is connected; and an in-line high-pressure fuel pump which is connected to the vapor separator via a fuel pipe and to whose upper portion an air vent pipe passing a position higher than the fuel pipe is connected, wherein the vapor vent pipe includes a folded portion formed so as to extend toward the other side out of the left and right sides of the engine and thereafter return to the one side.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2012-002457, filed on Jan. 10, 2012, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a fuel supply system of an outboard motor for supplying a fuel stored in a fuel tank to an intake port of an engine. 
         [0004]    2. Description of the Related Art 
         [0005]    An outboard motor often used in a small craft is generally provided with a fuel supply system for supplying an intake port of an engine of the outboard motor with a fuel stored in a fuel tank provided on a hull side. 
         [0006]    In this fuel supply system, a vapor separator for separating the fuel such as gasoline sucked up from the fuel tank by a low-pressure fuel pump into gas and liquid to release fuel vapor into the atmosphere, a fuel cooler for cooling the fuel having passed through the vapor separator by cooling water (seawater), a high-pressure fuel pump for pumping the fuel having passed through the fuel cooler, a pressure regulator for adjusting pressure of the fuel, an injector for injecting the fuel whose pressure has been adjusted by the pressure regulator to the intake port of the engine, and so on are generally provided. 
         [0007]    As a conventional fuel supply system of this type, for example, one in which a high-pressure fuel pump and a pressure regulator are integrally provided in a case of a vapor separator and a water jacket (fuel cooler) for cooling the fuel is also provided in the case of the vapor separator, whereby a fuel system is simplified (for example, refer to Patent Document 1), and the like are publicly known. 
         [0008]    However, in this fuel supply system, since the vapor separator and the high-pressure fuel pump are integrally provided, the size of the vapor separator becomes large for an outboard motor, which has a problem of difficulty in making the outboard motor compact. 
         [0009]    Therefore, conventionally, a fuel supply system provided with what is called an in-line high-pressure fuel pump connected in the middle of a fuel pipe and also is provided with a vapor separator having an atmosphere open valve for vapor vent (for example, refer to Patent Document 2) and the like have been publicly known. 
         [0010]    [Patent Document 1] Japanese Laid-open Patent Publication No. 10-218089 
         [0011]    [Patent Document 2] Japanese Laid-open Patent Publication No. 2002-235627 
         [0012]    However, generally adopting a structure in which an air vent pipe of the high-pressure fuel pump is returned to the vapor separator, the above-described conventional fuel supply system using the in-line high-pressure fuel pump has a problem that during the operation, the high-pressure fuel pump sucks the fuel inside the vapor separator through the air vent pipe, which is liable to disable the discharge of the air inside the high-pressure fuel pump. 
         [0013]    Another problem is that the outboard motor, when detached from a stern board for maintenance or the like, is usually placed on a floor in a lying posture with its vapor separator side down, and at this time, the fuel is liable to leak from the vapor vent pipe or the like of the vapor separator. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention was made to solve the above-described problems and has an object to provide a fuel supply system of an outboard motor which makes it possible to surely discharge the air in a high-pressure fuel pump during the operation of the outboard motor and prevent the leakage of the fuel regardless of the posture of the outboard motor. 
         [0015]    To attain the above object, the present invention is a fuel supply system of an outboard motor for supplying a fuel stored in a fuel tank to an intake port of an engine, the fuel supply system including: a vapor separator which is disposed on one of left and right sides of the engine in terms of a traveling direction of a hull and to whose upper portion a vapor vent pipe having a tip open to an atmosphere is connected; and an in-line high-pressure fuel pump which is connected to the vapor separator via a fuel pipe and to whose upper portion an air vent pipe passing a position higher than the fuel pipe is connected, wherein the vapor vent pipe includes a folded portion formed so as to extend toward the other side out of the left and right sides and thereafter return to the one side. 
         [0016]    Further, in the fuel supply system of the outboard motor according to the present invention, in a plane view, the air vent pipe of the high-pressure fuel pump may pass a position deviating from a recoil cover provided on an upper side of the engine, which position is closer to the one side than the folded portion of the vapor vent pipe, to be connected to the upper portion of the vapor separator. 
         [0017]    Further, in the fuel supply system of the outboard motor according to the present invention, in a plane view, the air vent pipe of the high-pressure fuel pump may pass a position deviating from a recoil cover provided on an upper side of the engine, which position is closer to the one side than the folded portion of the vapor vent pipe, and join the vapor vent pipe of the vapor separator to be open to the atmosphere, with the folded portion being formed after a joining portion of the air vent pipe and the vapor vent pipe. 
         [0018]    Further, in the fuel supply system of the outboard motor according to the present invention, in a plane view, the air vent pipe of the high-pressure fuel pump may pass a position above a recoil cover provided on an upper side of the engine, which position is closer to the one side than the folded portion of the vapor vent pipe, to be connected to the upper portion of the vapor separator. 
         [0019]    Further, in the fuel supply system of the outboard motor according to the present invention, the air vent pipe of the high-pressure fuel pump may join the vapor vent pipe above the recoil cover provided on an upper side of the engine to be open to the atmosphere, with the folded portion being formed after a joining portion of the air vent pipe and the vapor vent pipe. 
         [0020]    Further, in the fuel supply system of the outboard motor according to the present invention, the air vent pipe of the high-pressure fuel pump may pass a position above a recoil cover provided on an upper side of the engine, which position is closer to the other side than the folded portion of the vapor vent pipe, to be solely open to the atmosphere. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]      FIG. 1  is a left side view showing an outboard motor including a fuel supply system according to a first embodiment. 
           [0022]      FIG. 2  is a left side view showing an engine including the fuel supply system according to the first embodiment. 
           [0023]      FIG. 3  is a plane view showing the engine including the fuel supply system according to the first embodiment. 
           [0024]      FIG. 4  is a rear view showing the engine including the fuel supply system according to the first embodiment. 
           [0025]      FIG. 5  is a left side view showing a vapor separator of the fuel supply system according to the first embodiment. 
           [0026]      FIG. 6  is a plane view showing an engine including a fuel supply system according to a second embodiment. 
           [0027]      FIG. 7  is a rear view showing the engine including the fuel supply system according to the second embodiment. 
           [0028]      FIG. 8  is a plane view showing an engine including a fuel supply system according to a third embodiment. 
           [0029]      FIG. 9  is a plane view showing an engine including a fuel supply system according to a fourth embodiment. 
           [0030]      FIG. 10  is a plane view showing an engine including a fuel supply system according to a fifth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the following description, front, rear, left, and right directions are based on a travelling direction of a hull. 
       First Embodiment  
       [0032]      FIG. 1  is a left side view showing an outboard motor  2  including a fuel supply system according to a first embodiment of the present invention. The outboard motor  2  is mainly composed of a pair of left and right clamp brackets  3 , a swivel bracket  4  provided to be tiltable in an up and down direction relatively to the clamp brackets  3 , and an outboard motor body  5  held by the swivel bracket  4 . 
         [0033]    The clamp brackets  3  are each fixed to a hull  6  so as to sandwich an upper end of a stern board  7 , and on lower ends thereof, leg portions  8  are formed in parallel so as to face each other. A plurality of pin holes  9  are bored in each of the leg portions  8 , and in a side view, the pin holes  9  are arranged in a substantially arc shape with respect to a tilt shaft  10 . 
         [0034]    The swivel bracket  4  is disposed so as to be fitted between the clamp brackets  3 , and an upper portion of the swivel bracket  4  is pivotally supported on upper portions of the clamp brackets  3  via the tilt shaft  10 , thereby capable of tilting in the up and down direction. On a rear portion of the swivel bracket  4 , a pivot shaft is pivotably provided, and this pivot shaft is coupled to the outboard motor body  5 . An upper end portion of the pivot shaft projects forward to form a steering bracket  11 , and a steering handle  12  is pivotably attached to the steering bracket  11 . 
         [0035]    An engine  13  is installed in an upper portion of the outboard motor body  5 , and its periphery is covered by an engine cover  14 . The engine cover  14  is vertically dividable into an upper cover  15  and a lower cover  16 , the upper cover  15  covering an upper portion of the engine  13  and the lower cover  16  covering a lower portion of the engine  13 . 
         [0036]    In the engine  13 , a crankshaft is provided in a substantially vertical direction. A recoil  17  is provided on an upper end portion of the crankshaft, and a manual starter rope is wound around the recoil  17 . Further, an area above the recoil  17  is covered by a recoil cover  19 . 
         [0037]    Under the engine cover  14  across an oil pan  20 , a drive shaft housing  21  is provided. In the oil pan  20  and the drive shaft housing  21 , a drive shaft  22  coupled to a lower end of the crankshaft extends downward, so that a propeller  26  is driven via a bevel gear  24  and a propeller shaft  25  in a gear case  23  provided on a lower portion of the drive shaft housing  21 . 
         [0038]    Hereinafter, the fuel supply system  1  according to the first embodiment of the present invention will be described in detail with reference to  FIG. 2  to  FIG. 5 . Here,  FIG. 2  is a left side view showing the engine including the fuel supply system according to the first embodiment of the present invention.  FIG. 3  is a plane view showing the engine including the fuel supply system according to the first embodiment of the present invention.  FIG. 4  is a rear view showing the engine including the fuel supply system according to the first embodiment of the present invention.  FIG. 5  is a left side view showing a vapor separator of the fuel supply system according to the first embodiment of the present invention. 
         [0039]    As shown in  FIG. 2  to  FIG. 4 , the engine  13  is, for example, a water-cooled cycle four-cylinder engine, and is composed of the combination of a cylinder head  55 , a cylinder block  56 , a crankcase  57 , and so on. In the cylinder head  55 , an intake port and an exhaust port connecting to a combustion chamber are formed. Further, an injector  58  which injects a fuel into the intake port is attached to the cylinder head  55  from the outside. 
         [0040]    Around the engine  13 , the fuel supply system  1  is disposed. The fuel supply system  1  is a system to supply the intake port of the engine  13  with the fuel such as gasoline stored in a fuel tank provided on the hull  6  side and is composed of components such as a low-pressure fuel filter  29 , a low-pressure fuel pump  30 , a vapor separator  31 , a fuel cooler  32 , a high-pressure fuel pump  33 , a pressure regulator and a high-pressure fuel filter which are provided in the high-pressure fuel pump  33 , the injector  58 , and so on, these components being provided from the fuel tank side toward the intake port. 
         [0041]    The low-pressure fuel filter  29  has a substantially columnar outer shape and is disposed at a substantially center portion of a left side of the engine  13 . A fuel pipe  37   a  extending from the fuel tank is connected to a front surface of the low-pressure fuel filter  29 . The fuel pipe  37   a  is formed so as to tilt up toward the low-pressure fuel filter  29  provided at the rear thereof. Further, a fuel pipe  37   b  extending toward the low-pressure fuel pump  30  is connected to an upper surface of the low-pressure fuel filter  29 . The fuel pipe  37   b  is formed so as to tilt down toward the low-pressure fuel pump  30  provided at the rear thereof after rising substantially vertically. 
         [0042]    The low-pressure fuel pump  30  has a flat columnar outer shape and is disposed at a substantially center portion of a rear side of the engine  13 . The fuel pipe  37   b  extending from the low-pressure fuel filter  29  is connected to a left side surface of the low-pressure fuel pump  30 . Further, a fuel pipe  37   c  extending toward the vapor separator  31  is connected to the left side surface of the low-pressure fuel pump  30  so as to be above a connection portion of the fuel pipe  37   b.  These fuel pipes  37   b,    37   c  both extend upward after extending from the left side surface of the low-pressure fuel pump  30  and are arranged substantially in parallel. 
         [0043]    The vapor separator  31  has a substantially columnar outer shape, and on the left side of the engine  13 , it is disposed at the rear of and slightly above the low pressure fuel filter  29  so as to be close to the low-pressure fuel filter  29 . The fuel pipe  37   c  extending from the low-pressure fuel pump  30  is connected to an upper surface of the vapor separator  31 . Further, an air vent pipe  52  of the high-pressure fuel pump  33  is connected to the upper surface of the vapor separator  31  so as to be more forward than a connection portion of the fuel pipe  37   c.  The air vent pipe  52  is disposed above the fuel pipe  37   c.  Further, a vapor vent pipe  38  of the vapor separator  31  is connected to the upper surface of the vapor separator  31  so as to be more forward than a connection portion of the air vent pipe  52 . 
         [0044]    The vapor vent pipe  38  of the vapor separator  31  includes a folded portion  38   a  that is formed above the recoil cover  19  provided on an upper side of the engine  13 , so as to extend toward a right side of the engine  13  and thereafter be folded forward to return to the left side. A tip  38   b  of the vapor vent pipe  38  is open to the atmosphere. 
         [0045]    Further, a fuel return pipe  39  extending from the high-pressure fuel pump  33  is connected to a rear surface of the vapor separator  31 . Further, a fuel pipe  37   d  extending to the fuel cooler  32  is connected to a lower surface of the vapor separator  31 . 
         [0046]    The fuel cooler  32  has a flat shape and on the left side of the engine  13 , it is disposed under the vapor separator  31 . The fuel pipe  37   d  extending from the vapor separator  31  is connected to an upper surface of the fuel cooler  32 . Further, a fuel pipe  37   e  extending toward the high-pressure fuel pump  33  is connected to a rear surface of the fuel cooler  32 . The fuel pipe  37   e  is formed so as to once tilt down toward the high-pressure fuel pump  33  provided at the rear thereof and thereafter tilt up. 
         [0047]    A drain pipe  45  is connected to a front surface of the fuel cooler  32  and a tip of the drain pipe  45  is opened. The drain pipe  45  is formed to be capable of communicating with the fuel pipe  37   e  via a fuel path formed inside the fuel cooler  32 , and a valve is interposed in the middle of the fuel path. On the upper surface of the fuel cooler  32 , an operation part  47  of the valve is projectingly provided. By inserting a tool such as a socket wrench or a driver from an upper opening portion of the lower cover  16  and operating the operation part  47  to rotate it, it is possible to open/close the fuel path between the drain pipe  45  and the fuel pipe  37   e.    
         [0048]    Further, inside the fuel cooler  32 , a cooling water path is penetratingly provided linearly from its front surface lower portion toward its rear surface lower portion, and cooling water pipes  51  are connected to a front inlet and a rear outlet of the cooling water path respectively. 
         [0049]    Referring to  FIG. 2  and  FIG. 3  again, the high-pressure fuel pump  33  is what is called an in-line fuel pump connected in the middle of the fuel pipe to be used and is disposed on the rear side of the engine  13  so as to be under and close to the low-pressure fuel pump  30 . The fuel pipe  37   e  extending from the fuel cooler  32  is connected to a lower side of the high-pressure fuel pump  33 . Further, the fuel return pipe  39  is connected to an upper side of the high-pressure fuel pump  33 , and the fuel return pipe  39  is connected to the rear surface of the vapor separator  31 . 
         [0050]    Further, the air vent pipe  52  is connected to the upper side of the high-pressure fuel pump  33  so as to be adjacent to the fuel return pipe  39 . As shown in  FIG. 3 , in a plane view, the air vent pipe  52  passes a position deviating from an area above the recoil cover  19 , which position is closer to the left side than the folded portion  38   a  of the vapor vent pipe  38 . Further, as shown in  FIG. 2 , the air vent pipe  52  extends upward from the high-pressure fuel pump  33 , thereafter curves substantially vertically downward above the vapor separator  31 , is connected to the upper surface of the vapor separator  31 , and passes a position higher than the fuel pipe  37   e  and the fuel return pipe  39  in a side view. 
         [0051]    Further, a fuel pipe  37   f  extending toward the injector  58  is connected to a right side surface of the high-pressure fuel pump  33 . The fuel pipe  37   f  is formed so as to extend upward. 
         [0052]    Next, the operation of the fuel supply system  1  according to the first embodiment of the present invention will be described. 
         [0053]    The fuel in the fuel tank provided on the hull  6  side is sucked up by the low-pressure fuel pump  30 , is filtrated by the low-pressure fuel filter  29 , thereafter passes through the fuel pipe  37   b  to be led to the low-pressure fuel pump  30 , and passes through the fuel pipe  37   c  from the low-pressure fuel pump  30  to be led to the inside of the vapor separator  31 . 
         [0054]    Inside the vapor separator  31 , the fuel is separated into gas and liquid, and fuel vapor is released to the atmosphere through the vapor vent pipe  38 , and the liquid of the fuel from which the vapor has been removed passes through the fuel pipe  37   d  to flow into the fuel cooler  32 . 
         [0055]    In the fuel cooler  32 , heat exchange takes place between seawater circulating in the cooling water pipes  51  and the liquid fuel, so that the liquid fuel is cooled, and the liquid fuel is sent to the high-pressure fuel pump  33  through the fuel pipe  37   e.    
         [0056]    Thereafter, the liquid fuel is pumped by the high-pressure fuel pump  33 , and after being adjusted in pressure by the pressure regulator and filtrated by the high-pressure fuel filter, the liquid fuel passes through the fuel pipe  37   f  to be sent to the injector  58 , and the fuel is sprayed into the intake port by the injector  58 . 
         [0057]    Here, after extending upward from the high-pressure fuel pump  33  in a side view, the air vent pipe  52  of the high-pressure fuel pump  33  curves substantially vertically downward above the vapor separator  31  to be connected to the upper surface of the vapor separator  31  so as to pass the position higher than the fuel pipe  37   e  and the fuel return pipe  39 . Therefore, there is no concern that the high-pressure fuel pump  33  sucks the fuel inside the vapor separator  31  through the air vent pipe  52  during the operation. Consequently, it is possible to surely discharge the air inside the high-pressure fuel pump  33  to the atmosphere via the air vent pipe  52  and the vapor vent pipe  38 , which makes it possible to normally operate the high-pressure fuel pump  33 . 
         [0058]    Further, the air vent pipe  52  of the high-pressure fuel pump  33  passes the shortest route at the position deviating from the area above the recoil cover  19 , which position is closer to the left side than the folded portion  38   a  of the vapor vent pipe  38  in a plane view. This makes it possible to make the outboard motor body  5  compact. 
         [0059]    Further, the vapor vent pipe  38  of the vapor separator  31  has the folded portion  38   a  which is formed above the recoil cover  19  so as to extend toward the right side of the outboard motor body  5  and thereafter return to the left side. Therefore, even when the outboard motor is detached from the stern board for maintenance or the like and is placed on a floor in a lying posture with its vapor separator  31  side (left side) down, there is no concern about the leakage of the fuel from the vapor vent pipe  38  of the vapor separator  31 . This makes it possible to improve maintenability of the outboard motor  2 . 
         [0060]    Hereinafter, as other embodiments of the present invention, modification examples of the first embodiment will be described. Note that the same constituent elements as those of the first embodiment will be denoted by the same reference signs and a detailed description thereof will be omitted. The description will be focused on what are different from the first embodiment. 
       Second Embodiment  
       [0061]    As shown in  FIG. 6  and  FIG. 7 , the air vent pipe  52  of the high-pressure fuel pump  33  may join the vapor vent pipe  38  of the vapor separator  31  above the recoil cover  19  to be open to the atmosphere, with the folded portion  38   a  being formed at a position after a joining portion of the air vent pipe  52  and the vapor vent pipe  38 . In this case, at the joining portion of the air vent pipe  52  and the vapor vent pipe  38 , a 3-way union joint  60  is provided. 
       Third Embodiment  
       [0062]    As shown in  FIG. 8 , in a plane view, the air vent pipe  52  of the high-pressure fuel pump  33  may pass a position deviating from the recoil cover  19 , which position is closer to the left side than the folded portion  38   a  of the vapor vent pipe  38  of the vapor separator  31  and join the vapor vent pipe  38  of the vapor separator  31  to be open to the atmosphere, with the folded portion  38   a  being formed at a position after a joining portion of the air vent pipe  52  and the vapor vent pipe  38 . 
       Fourth Embodiment  
       [0063]    As shown in  FIG. 9 , in a plane view, the air vent pipe  52  of the high-pressure fuel pump  33  may pass a position above the recoil cover  19 , which position is closer to the left side than the folded portion  38   a  of the vapor vent pipe  38  of the vapor separator  31 , to be connected to the upper portion of the vapor separator  31 . 
       Fifth Embodiment  
       [0064]    As shown in  FIG. 10 , the air vent pipe  52  of the high-pressure fuel pump  33  may pass a position above the recoil cover  19 , which position is closer to the right side than the folded portion  38   a  of the vapor vent pipe  38  of the vapor separator  31 , in parallel to the vapor vent pipe  38 , to be solely open to the atmosphere. 
         [0065]    In the description of the foregoing embodiments of the present invention, only suitable examples of the fuel supply system of the outboard motor according to the present invention are shown, and the technical scope of the present invention is not limited to these forms unless there is a description particularly limiting the present invention, and various modifications can be made. 
         [0066]    According to the present invention, it is possible to obtain various excellent effects such as that the air in a high-pressure fuel pump can be surely discharged during the operation of an outboard motor, that the leakage of a fuel can be prevented regardless of a posture of the outboard motor, and so on.