Patent Publication Number: US-6216672-B1

Title: Fuel supply system of outboard motor

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a fuel supply system of an outboard motor. 
     In a known art, an outboard motor is provided with a fuel supply system or apparatus for fuel injection type engine, and such fuel supply system is operated in a manner that a fuel in a fuel tank is guided to a vapor separator by means of a low pressure fuel pump, then delivered to a high pressure fuel filter by means of a high pressure fuel pump and filtered therein, and thereafter, is guided to an intake port by a fuel injector through a delivery pipe. An extra amount of the fuel fed to the fuel injector is delivered to a pressure regulator from a downstream side of the delivery pipe and is thereafter returned to the vapor separator after a fuel pressure has been lowered. 
     In the conventional structure, however, since the vapor separator and the pressure regulator are arranged apart from each other around an engine. Accordingly, a space around the engine is not effectively utilized and, in addition, duct or pipe arrangement is made complicated. 
     Furthermore, in the conventional structure, fuel elements or members constituting the fuel supply system such as a vapor separator, a pressure regulator, a fuel pump, a fuel filter, etc. are arranged or mounted to various portions of the engine, thus being inconvenient for performing maintenance or inspection of the engine and making it difficult to realize a compact structure of the engine. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a fuel supply system of an outboard motor having a compact structure and having an improved arrangement of fuel elements to easily carry out maintenance work. 
     This and other objects can be achieved according to the present invention by providing a fuel supply system of an outboard motor, particularly of a fuel-injection type, comprising: 
     a fuel tank in which a fuel to be supplied is stored; 
     a low pressure fuel filter and a low pressure fuel pump connected to the fuel tank through a fuel supply hose; 
     a vapor separator connected to the low pressure fuel pump through a low pressure fuel hose; 
     a high pressure fuel pump disposed inside the vapor separator; 
     a pressure regulator disposed inside the vapor separator; 
     a fuel hose having one end connected to the high pressure fuel pump; 
     a branch pipe incorporated on the way of the fuel hose means and having one end connected to the pressure regulator through a hose; and 
     a delivery pipe connected to another one end of the branch pipe. 
     In a preferred embodiment, a plurality of fuel injectors are connected to the delivery pipe and adapted to inject the fuel with pressure regulated by the pressure regulator. 
     The respective elements or parts mentioned above are integrally mounted to a mount base such as intake manifolds of an outboard motor. 
     A high pressure fuel filter is further disposed on the way of the fuel hose operatively connecting the high pressure fuel pump and the delivery pipe. 
     The vapor separator has an inner space sectioned by a partition plate into upper and lower portions in which the high pressure fuel filter and the pressure regulator are arranged respectively. 
     According to the structure of the fuel supply system of an outboard motor mentioned above, the fuel supply system can be made more unitive and the number of parts or elements to be arranged can be reduced, thus making the entire structure simple and compact. 
     The fuel elements or parts constituting the fuel supply system are mounted integrally to the intake manifold as mount base. Therefore, all the elements or parts of the fuel supply system can be integrally dismounted by removing the low pressure fuel hose from the low pressure fuel pump. As a result, the maintenance of the engine can be effectively performed and the fuel supply system itself can be made more unitive. Furthermore, re-assembling of such fuel supply system can be also done more simply. 
     The location of the high pressure fuel filter between the vapor separator and the delivery pipe can prevent foreign matters or the like from entering into the fuel injectors, thus the system being reliable. 
     Still furthermore, according to the present invention, since the fuel discharge port as the high pressure fuel outlet is formed to, for example, the upper portion of the vapor separator and the pressure regulator as the high pressure fuel inlet is located to, for example, the lower portion of the vapor separator, the overlapped arrangement of the fuel hoses can be prevented, thereby making the pipe (piping) arrangement compact. 
     The nature and further characteristic features of the present invention will be made more clear from the following description made with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a left-side view of an outboard motor having a fuel supply system according to one embodiment of the present invention in a state mounted to a hull; 
     FIG. 2 is a side view, in an enlarged scale, of an engine of the outboard motor of FIG. 1; and 
     FIG. 3 is a block diagram of the fuel supply system of the outboard motor of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     One preferred embodiment of the present invention will be described hereunder with reference to the accompanying drawings. 
     First, FIG. 1, shows an outboard motor  1  equipped with a fuel supply system or apparatus according to the present invention in a state mounted to a transom  5   a  of a hull  5 . 
     The outboard motor  1  is provided with an engine holder  2  above which an engine or engine unit  3  is disposed. The engine holder  2  is provided with a bracket  4  through which the outboard motor  1  is mounted to the transom  5   a  of the hull  5 . 
     Next, FIG. 2, shows the engine  3  of the outboard motor, the engine unit  3  mounted to the outboard motor  1  is, for example, a water-cooled four-stroke-cycle three-cylinder engine, and is assembled with a cylinder head  6 , a cylinder block  7 , crank case  8 , etc. The outer periphery of the engine  3  is covered by an outboard motor cover  9 . 
     The cylinder block  7  is arranged to a portion at a rear side of the crank case  8  disposed at the most forward portion, left-side as viewed in FIG. 2, of the engine  3 , and the cylinder head  6  is disposed at the rear portion of the cylinder block  7 . The rear side portion of the cylinder head  6  is covered by a head cover  10 , and a crank shaft  11  is arranged substantially vertically at a mating portion of the crank case  8  and the cylinder block  7  (FIG.  1 ). 
     Referring to FIG. 1, a drive shaft housing  12  is disposed below the engine  3 . An upper end of a drive shaft  13  is coupled to the lower end of the crank shaft  11  through a spline coupling, for example, and the drive shaft  13  extends downward therefrom inside the drive shaft housing  12 . The lower end of the drive shaft  13  is engaged with a bevel gear  15  and a propeller shaft arranged in a gear case  14  disposed below the drive shaft housing  12  thereby to drive a propeller  17  of the outboard motor  1 . 
     As shown in FIG. 2, there are arranged, around the engine  3 , electrical equipments, not shown, an intake device  18 , a fuel supply system or apparatus  19 , etc. The intake device is mainly composed of a silencer  20 , a throttle body  21 , a surge tank  22  and intake manifolds  23  extending from the surge tank  22  to respective cylinders, these elements being arranged concentrically on one side, left side in this embodiment, of the engine  3 . The electrical equipments are also arranged concentrically on the side opposite to the intake device  18 . 
     The throttle body  21  composing the intake device  18  is disposed at a left front portion, for example, of the crank case  8 , and the silencer  20  is disposed on the upstream side of the throttle body  21  and, on the other hand, the surge tank  22  is disposed on the downstream side thereof. The intake manifolds  23  are vertically arranged on the side of the cylinder block  7  so as to communicate the inside of the surge tank  22  with intake ports formed to the cylinder head  6 . 
     The fuel supply system  19  includes fuel elements or parts such as filters, pumps, etc. More concretely, the fuel supply system  19  is composed of low and high pressure filters  24 L and  24 H, low and high pressure fuel pumps  25 L and  25 H, a vapor separator  26 , a pressure regulator  27 , a delivery pipe  28  and a fuel injector  29 , which are operatively connected respectively by means of low and high pressure fuel hoses  30 L and  30 H. 
     FIG. 3 is a block diagram of the fuel supply system  19  according to the present invention. The outboard motor  1  of this embodiment is equipped with a fuel tank  31  on the hull  5  side, and as shown in FIG. 3, a fuel supply hose  32  extending from the fuel tank  31  is connected to the low pressure fuel filter  24 L. 
     The low pressure fuel pump  25 L driven by a camshaft, not shown, constituting a valve moving mechanism of the engine, is arranged to the head cover  10 , and the low pressure fuel pump  25 L (mechanical pump) and the low pressure fuel filter  24 L are connected to each other by means of the low pressure fuel hose  30 L. 
     The vapor separator  26  is arranged in a space formed between the side surface of the cylinder block  7  and the intake manifolds  23 , and the vapor separator  26  is secured to an inside portion of the intake manifolds  23  as a mount base by means of bolts  33 , for example. The vapor separator  26  acts to separate a vapor contained in a liquid fuel, such as gasoline vapor contained in a gasoline and release only the vapor in air, and the fuel is fed to the vapor separator  26  from the low pressure fuel pump  25 L through the low pressure fuel hose  30 L. 
     The vapor separator  26  is accommodated with the high pressure fuel pump  25 H for feeding, under a predetermined pressure, the fuel from which the vapor is separated, to the high pressure fuel filter  24 H through the high pressure hose  30 H. The high pressure fuel filter  24 H is secured to the delivery pipe  28  through a bracket  34  disposed to a portion, for example, between a plurality of fuel injectors  29 . 
     The highly pressurized fuel fed to the high pressure fuel filter  24 H is then fed to the delivery pipe  28  integrally mounted to the intake manifolds  23  through the high pressure hose  30 H. The fuel injectors  29  are mounted to the delivery pipe  28  for the respective cylinders and the fuel injectors  29  then inject the highly pressurized fuel into the intake ports of the cylinders. 
     A fuel flow-in portion  37  is arranged to an upper portion of an inner surface of the vapor separator  26  and a needle valve  39  is disposed at an outlet portion of the fuel flow-in portion  37 . A float  40  is also disposed at a portion near this outlet portion of the fuel flow-in portion  37 . The float  40  is supported to be swingable by means of hinge  41 , for example, to which the needle valve  39  is mounted. 
     The high pressure fuel pump  25 H is mounted to an upstream side of a fuel discharge portion  38  arranged to the upper portion inside the vapor separator  26 . The inside of the vapor separator  26  is formed as a fuel reservoir in which the high pressure fuel pump  25 H is immersed. A chamber  43  is formed at a lower portion of the fuel reservoir by being sectioned by a partition plate  42 . The pressure regulator  27  as inlet means of the high pressure fuel is arranged in this chamber  43 . The partition plate  42  is formed with a communication port  44  for establishing the communication between the fuel reservoir and the chamber  43 . 
     As shown in FIGS. 2 and 3, a branch pipe  45  is disposed on the way of the high pressure fuel hose  30  extending from the high pressure fuel filter  24 H to the delivery pipe  28 , and one downstream end of the branch pipe  45  is connected to the high pressure fuel hose  30 H extending to the delivery pipe  28  and another one end of the branch pipe  45  is connected to a hose  46  extending to the vapor separator  26 , the hose  46  being then connected to the pressure regulator  27  in the vapor separator  26 . 
     The fuel supply system of the structure mentioned above will operates in the following manner. 
     The fuel in the fuel tank  31  is sucked up by the low pressure fuel pump  25 L, then filtered by the low pressure fuel filter  24 L and guided to the vapor separator  26  through the fuel flow-in portion  37 . When the fuel level in the vapor separator  26  reaches a predetermined level, the float  40  is floated up and the needle valve  39  closes the outlet of the fuel flow-in portion  37  thereby to restrict the fuel flow-in condition, thus preventing the fuel from overflowing. On the other hand, when the fuel level lowers as the fuel has been consumed, the float  40  is also lowered thereby to release the outlet of the fuel flow-in portion to again supply the fuel. 
     In the vapor separator  26 , vapor from the fuel stored therein is separated and bubbles of the vapor are released in the air (atmosphere), and the fuel with substantially no vapor is supplied to the delivery pipe  28  by means of the high pressure fuel pump  25 H through the fuel discharge outlet  38  and the high pressure fuel filter  24 H. Thereafter, the highly pressurized fuel is injected into the intake ports through the fuel injectors  29 . During this operation, as far as the fuel injection has been normally carried out, the fuel pressure in the hose  46  extending from the branch pipe  45  is less than the prescribed pressure, so that the pressure regulator  27  is not opened. 
     On the contrary, at a time when the fuel pressure in the delivery pipe  28  is increased more than the prescribed value because of, for example, the reduced fuel consumption due to low revolution speed of the engine  3 , the fuel pressure in the hose  46  is also increased. Accordingly, the pressure regulator  27  is opened and the fuel pressure in the delivery pipe  28  is lowered. 
     As mentioned above, according to the arrangement of the pressure regulator  27  in the vapor separator  26 , the fuel supply system can be made more unitive and the number of parts or elements to be arranged can be reduced, thus making the entire structure simple and compact. 
     The fuel elements or parts constituting the fuel supply system  19  such as the high pressure filter  24 H, the high pressure fuel pump  25 H, the vapor separator  26 , the pressure regulator  27 , the delivery pipe  28  and the fuel injectors  29  are mounted integrally to the intake manifold means  23  as mount base. Therefore, all the elements or parts of the fuel supply system  19  can be integrally dismounted by removing the low pressure fuel hose  30  from the low pressure fuel pump  25 L. As a result, the maintenance of the engine can be effectively performed and the fuel supply system  19  itself can be made more unitive. Furthermore, re-assembling of such fuel supply system can be also done more simply. 
     Still furthermore, the location of the high pressure fuel filter  24 H between the vapor separator  26  and the delivery pipe  28  can prevent foreign matters or the like from entering into the fuel injectors  29 , thus the system being reliable. 
     Still furthermore, according to the present invention, since the fuel discharge port  38  as the high pressure fuel outlet is formed to, for example, the upper portion of the vapor separator  26  and the pressure regulator  27  as the high pressure fuel inlet is located to, for example, the lower portion of the vapor separator  26 , the overlapped arrangement of the fuel hoses  30 H can be prevented, thereby making the pipe (piping) arrangement compact. 
     It is to be noted that the present invention is not limited to the described embodiment and many other changes and modifications may be made without departing from the scopes of the appended claims.