Abstract:
A fuel pump layout structure in a motorcycle, including an engine, a fuel pump for the supplying fuel to the engine, a frame for supporting the engine and the fuel pump, and a rear suspension damper disposed behind the frame with a swing arm being swingably suspended from the rear suspension damper, wherein said fuel pump is disposed on one side of said rear suspension damper.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a fuel pump layout structure in a motorcycle for disposing a fuel pump behind an engine. 
     There is known a motorcycle which positions a fuel pump outside a fuel tank. In a certain motorcycle of such a type, a fuel pump is disposed within a main frame (body frame) which supports an engine and behind the engine (see, for example, Japanese Patent Laid-Open No. 2005-096504). 
     However, in the case where an auxiliary device (e.g., a starting motor) of the engine is disposed on an engine crank case, it is difficult to ensure space for a fuel pump within a main frame. 
     According to another layout, a fuel pump is disposed sideways of the portion between an engine and a center frame which constitutes a rear portion of a main frame. However, from the standpoint of rider&#39;s operation, it is not good for the fuel pump to project sideways. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished in view of the above-mentioned circumstances and it is an object of the present invention to provide a fuel pump layout structure in a motorcycle not affected by the layout of an auxiliary device of the engine. 
     According to the present invention there is provided a fuel pump layout structure in a motorcycle including: an engine; a fuel pump for the supply of fuel to the engine; a frame for supporting the engine and the fuel pump; and a rear suspension damper disposed behind the frame with a swing arm being suspended from the rear suspension damper swingably; characterized in that the fuel pump is disposed on one side of the rear suspension damper. 
     According to this construction, the layout of the fuel pump does not exert any influence on the layout of an auxiliary device of the engine, nor does the fuel pump project sideways of the vehicle body. 
     An intake part and an exhaust part both connected to the engine may be disposed on the other side of the rear suspension damper. 
     According to this construction, the fuel pump and intake and exhaust parts can be arranged in an optimum layout near the frame. 
     Further, the fuel pump may be attached to the frame through a bracket and a rubber member may be interposed between the bracket and the fuel pump and also between the bracket and the frame. 
     According to this construction, vibration on the vehicle body side can be absorbed by the rubber member. 
     According to the present invention, in a fuel pump layout structure in a motorcycle including: an engine; a fuel pump for the supply of fuel to the engine; a frame for supporting the engine and the fuel pump; and a rear suspension damper disposed behind the frame with a swing arm being suspended from the rear suspension damper swingably. Since the fuel pump is disposed on one side of the rear suspension damper, the layout of the fuel pump is not influenced by the layout of an auxiliary device of the engine. 
     Besides, the fuel pump can be located without projecting it sideways of the vehicle body. 
     Moreover, the fuel pump can be disposed (or located) at a position spaced away from the engine but not too long in distance from the engine as compared with the conventional mounting position of the fuel pump. As a result, it is possible to make the fuel pump difficult to undergo the influence of heat from the engine in comparison with the prior art. 
     Further, since intake and exhaust parts connected to the engine are disposed on the other side of the rear suspension damper, the fuel pump and the intake and exhaust parts can be disposed in an optimum layout near the frame. As a result, it is possible to prevent a fuel supply line from becoming too long while positioning the fuel pump behind the engine by effectively utilizing the space around the frame. 
     Additionally, since the fuel pump is attached to the frame through a bracket and a rubber member is interposed between the bracket and the fuel pump and also between the bracket and the frame, vibration on the vehicle body side can be absorbed by the rubber member. As a result, vibration is no longer propagated to the fuel pump and it is possible to improve the reliability of the fuel pump operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a left side view of a motorcycle related to an embodiment of the present invention; 
         FIG. 2  is a partial plan view of the motorcycle of  FIG. 1  as seen from above a vehicle body frame; 
         FIG. 3  is a right, front perspective view of  FIG. 2 ; 
         FIG. 4  is a right, rear perspective view of  FIG. 2 ; 
         FIG. 5(   a ) is a plan view of a fuel pump alone and  FIG. 5(   b ) is a front view thereof, partly in cross section; and 
         FIG. 6(   a ) is a cross sectional view of a fuel pump mounting bracket, and  FIG. 6(   b ) is a cross sectional view taken on line  6 - 6  in  FIG. 4 , showing a fuel pump mounting portion. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A fuel pump layout structure in a motorcycle embodying the present invention will be described with reference to the drawings.  FIG. 1  is a left side view showing an off-road motorcycle  1  related to this embodiment. Directions which will be referred to in the following description are based on  FIG. 1 . It is assumed that a vertical direction of the vehicle body is the vertical direction in  FIG. 1 , a transverse direction of the vehicle body is the depth direction of the paper in  FIG. 1 , and a longitudinal direction of the vehicle body is the transverse direction of the paper in  FIG. 1 . In  FIG. 1 , for ease of explanation, a side cover and a shroud, which cover an outside portion of the vehicle body, are omitted. 
     As shown in  FIG. 1 , a body frame  2  of the motorcycle  1  includes a main frame  10  extending backward and obliquely downward of the vehicle body from a head pipe  3 , a down tube  20 A extending below the main frame  10  downwards of the vehicle body from the head pipe, a pair of right and left lower pipes  20 B,  20 B contiguous to the down tube  20 A on the lower side of the tube and extending backward below the vehicle body, and a pair of right and left center frames  30 R,  30 L which connect between a rear end of the main frame  10  and rear ends of the lower pipes  20 B,  20 B. The body frame  2  constitutes a cradle type frame and inside the area surrounded with the body frame  2  there is suspended an engine  4  through an engine hanger. 
     A pair of rear frames  40  extending backward of the vehicle body are secured to the center frames  30 R and  30 L, respectively. The rear frames  40  are made up of a pair of right and left pipes  40 A,  40 A extending backward and obliquely upward of the vehicle body from lower portions of the center frames  30 L and  30 R and a pair of right and left pipes  40 B,  40 B extending backward of the vehicle body from upper portions of the center frames  30 L and  30 R. Rear ends of the pipes  40 A and  40 B are connected with each other. 
     A seat  57 , a rear fender  58  and side covers (not shown) are attached to the pipes  40 A and  40 B. 
     A pair of right and left front forks  61  which support a front wheel  60  through an axle are connected to the lower side of the head pipe  3 , while a top bridge  64  with a steering handle  63  fixed thereto is connected to the upper side of the head pipe  3 . Further, a front fender  65  is secured to the lower side of the head pipe  3  so as to cover the front wheel  60  from above. 
     The center frames  30  each have a bent portion  30 A on the lower side thereof and a pivot shaft  32  is provided in the bent portion  30 A so as to extend through the bent portion in the transverse direction of the vehicle body. A front end of a swing arm  71  which supports a rear wheel  70  through an axle is supported by the pivot shaft  32  so as to be vertically swingable. A drive chain  74  is entrained on a sprocket  72  mounted in the rear wheel  70  and also on a sprocket  73  mounted on an output shaft  5 A of the engine  4 . Driving force of the engine  4  is transmitted to the rear wheel  70  through the drive chain  74 . 
     Below the bent portion  30 A is positioned a cross member  79  (see  FIGS. 3 and 4 ) which connects the center frames  30 L and  30 R with each other transversely, and a frame-side bracket  33  is secured to the cross member  79  centrally in the transverse direction. On the other hand, in an upper portion of the swing arm  71 , a support portion  71   a  is formed (see  FIGS. 3 and 4 ) and a link  76  having a downwardly bent shape is attached to the support portion  71   a . More specifically, as shown in  FIGS. 1 ,  3  and  4 , one end of the link  76  is secured to the support portion  71   a , a downwardly bent base end thereof is secured to a lower side of a rear suspension damper  80 , and a bent lower end thereof is secured to the frame-side bracket  33  through a rod  75 . That is, the rod  75  inhibits the link  76  from rotating in the rotational direction based on a connection fulcrum between the link and the support portion  71  a of the swing arm  71 . 
     A gear change pedal  34  for the rider to put his or her foot thereon is provided in front of the bent portion  30 A and in the vicinity of a lower side portion of the engine  4  (sideways of the space between the engine  4  and the center frame  30 ). During travel of the vehicle, the rider&#39;s foot is always placed near the pedal  34 . 
     The engine  4  has a crank case  5 , a cylinder block  6  extending substantially upward from a front portion of the crank case  5 , and a cylinder head  7  connected to an upper portion of the cylinder block  6 . The engine  4  is a single-cylinder engine having one cylinder within the cylinder block  6 . In the cylinder block  6 , a piston is received within a cylinder in a reciprocatable manner. A crank shaft connected to the piston through a connecting rod and the output shaft  5 A of the engine are supported by the crank case  5 . A clutch mechanism and a transmission mechanism, which constitute a power transfer mechanism between the crank shaft and the output shaft  5 A, are received within the crank case  5 . A starting motor  88  (an auxiliary device of the engine) shown in  FIGS. 3 and 4  is disposed behind the engine  4  and in front of the center frames  30 R and  30 L. The crank shaft can be rotated by the starting motor  88 . 
     Intake/exhaust valves for opening and closing an intake/exhaust passage communicating with the cylinder in the cylinder block  6  are accommodated within the cylinder head  7  and an intake port  7 A of the intake/exhaust passage is formed in a rear face of the cylinder head  7 . A throttle body  8  is connected to the intake port  7 A and an air cleaner box  9  is connected to the throttle body  8 . 
     In a front face of the cylinder head  7  is formed an exhaust port  7 B of the intake/exhaust passage, and an exhaust pipe  50  is connected to the exhaust port  7 B. The exhaust pipe  50  extends forward from the exhaust port  7 B, then bends rightwards and sideways of the cylinder head  7  and further extends rearwards of the vehicle, with an exhaust muffler  51  being connected to the extending end of the exhaust pipe  50 . 
     A fuel tank  56  is disposed above the cylinder head  7  and in front of the seat  57 . Further, a fuel pump  81  for feeding fuel from the interior of the fuel tank  56  to the throttle body  8  is mounted below the fuel tank  56  and behind vertically central portions of the center frames  30 . 
       FIG. 2  is a plan view showing a top view of the fuel tank  56  as removed from the motorcycle of  FIG. 1 .  FIG. 3  is a perspective view of  FIG. 2  as seen from a front and obliquely right side and  FIG. 4  is a perspective view of  FIG. 2  as seen from a rear and obliquely right side. With reference to these figures, a description will be given below about the mounting position of the fuel pump  81 . 
     As shown in  FIG. 2 , two center frames  30 R and  30 L extend in a right-left branched fashion from a rear portion of the main frame  10  which extends longitudinally through the transversely central part of the vehicle body. An upper end of the rear suspension damper  80  is secured to the rear end of the main frame  10 . That is, the rear suspension damper  80  is disposed centrally of the vehicle body (see  FIG. 2 ) and obliquely downwards in the longitudinal direction from its upper end to lower end portion (see  FIGS. 1 ,  3  and  4 ). 
     The center frames  30 R and  30 L extend transversely from the rear portion of the main frame  10  and then extend downwards from near outer side portions of the vehicle body. The main frame  10  and the center frames  30 L,  30 R are columnar in shape. 
     On the right side of the main frame  10 , as shown in  FIG. 2 , the exhaust pipe  50  (exhaust part) extended from the exhaust port  7 B of the cylinder head  7  further extends longitudinally of the vehicle body. Moreover, as shown in  FIG. 2 , the throttle body  8  (intake part) is attached to an upper somewhat-near-the-center portion of the exhaust pipe  50  so as to extend backward and obliquely rightwards from the intake port  7 A of the cylinder head  7  through a cone tube  82 . The throttle body  8  is connected to a discharge port of the air cleaner box  9  (see  FIG. 1 ) which is positioned on an extension line of the cone tube  82 . 
     On the other hand, on the left side of the main frame  10 , as shown in  FIGS. 2 to 4 , the fuel pump  81  is disposed between the rear suspension damper  80  and the left center frame  30 L and behind and near the center frame  30 L. As shown in  FIG. 2 , the fuel pump  81  is disposed at a rear position with respect to the pivot shaft  32  which extends in the vehicular transverse direction, and as shown in  FIG. 4 , it is secured to the center frame  30 L through a bracket  100 . As to the details of the mounting portion, a description will be given later. 
     As shown in  FIGS. 1 and 3 , a fuel pipe  59   a  extending toward the fuel tank  56  which is positioned higher than the fuel pump  81 , as well as a breather tube  59   b , are connected to an upper end of the fuel pump  81 . The fuel pump  81  sucks in the fuel from the fuel tank  56  through the fuel pipe  59   a.    
     Further, as shown in  FIGS. 1 and 3 , a fuel pipe  59   c  extending toward the throttle valve  8  positioned higher than the fuel pump  81  is connected to an upper portion of the fuel pump  81 . Through the fuel pipe  59   c  the fuel pump  81  delivers the sucked-in fuel to the throttle valve  8 . 
     The fuel tank  56 , fuel pump  81  and throttle body  8  are arranged while ensuring a piping space so that their fuel supply line (length (distance) of the fuel pipes  59   a ,  59   c  and the breather tube  59   b ) is connected in this shortest distance. That is, the piping space is ensured so that the fuel supply line has a length falling under the range in which the fuel pump  81  can fully fulfill its function of sucking in fuel from the fuel tank  56  and feeding out the fuel. 
       FIG. 5(   a ) is a plan view of the fuel pump  81  and  FIG. 5(   b ) is a front view thereof, partly in section. 
     As shown in  FIG. 5(   b ), the fuel pump  81  is made up of a cap portion  82  and a housing portion  83  secured by caulking to a lower outer periphery edge of the cap portion  82 . As shown in  FIGS. 5(   a ) and  5 ( b ), the cap portion  82  is provided with a joint  82   a  projecting laterally and with the fuel pipe  59   c  attached thereto and joints  82   b  and  82   c  projecting upward and with both fuel pipe  59   a  and breather tube  59   b  attached thereto. A connector  84  for the supply of electric power to the fuel pump  81  projects upward on top of the cap portion  82 . A combustion chamber  85  is formed by both cap portion  82  and housing portion  83 . Further, a pump portion  86  and a filter mounted sideways of the pump portion  86  are accommodated within the combustion chamber  85 . 
     According to this construction, the fuel stored within the combustion chamber  85  is sucked up by the pump portion  86  through the filter  87  and is fed to the throttle body  8  through the fuel pipe  59   c . The fuel present within the fuel tank  56  is fed into the fuel tank  81  through the fuel pipe  59   a  by an amount corresponding to the amount of fuel fed out by the pump portion  86 . That is, the fuel pump  81  also functions as an auxiliary fuel tank. 
       FIG. 6(   a ) is a sectional view showing a bracket  100  for mounting the fuel pump. The bracket  100  is formed by bending a flat steel plate having elasticity and it includes an arcuate portion  100 A mounted in a winding fashion around the body portion of the fuel pump  81  and two fixing portions  100 B extending rectilinearly from ends of the arcuate portion. Further, mounting holes  100 C are formed in front end portions respectively of the fixing portions  100 B. 
     In the bracket  100  as a discrete part, as shown in  FIG. 6(   a ), the two fixing portions  100 B are spaced apart (opened) from each other in the circumferential direction of the arcuate portion  100 A (indicated by a solid line in  FIG. 6(   a )). On the other hand, when mounting the fuel pump  81 , the two mounting holes  100 C are superimposed one on the other (indicated by a dash-double dot line in  FIG. 6(   a )) by utilizing the elasticity of the arcuate portion  100 A, whereby the radial length of the arcuate portion  100 A is contracted to hold the body portion of the fuel pump  81  grippingly. 
       FIG. 6(   b ) is a sectional view taken on line  6 - 6  in  FIG. 4 , showing a mounting portion of the fuel pump  81 . 
     A rubber member  101  having elasticity is interposed between the arcuate portion  100 A of the bracket  100  and the fuel pump  81 . The rubber member  101  functions to prevent vibration from being propagated from the vehicle body side to the fuel pump  81  and its elastic modulus can be determined suitably on the basis of the model and displacement of the vehicle. 
     On the other hand, a metallic mounting piece  103  for mounting the bracket  100  is secured, for example, by welding to the center frame  30 L. A mounting hole  103 C is formed in a front end portion of the mounting piece  103 . By aligning the mounting hole  100 C of the bracket  100  with the mounting hole  103 C and clamping the two together by means of a clamping member  104 , the fuel pump  81  is fixed to the center hole  30 L. 
     As shown in  FIG. 6(   b ), sheet-like rubber members  102  are disposed between the metallic mounting piece  103  and the bracket  100  and also between the mounting piece  103  and the clamping member  104 . The rubber members  102 , like the rubber member  101 , also function to prevent vibration from being propagated from the vehicle body side to the fuel pump  81  and their elastic modulus can be determined suitably on the basis of the model and displacement of the vehicle. 
     According to the fuel pump layout structure in a motorcycle according to this embodiment of the present invention, since the fuel pump  81  is disposed behind the center frame  30 L and on the left side of the rear suspension damper  80 , the influence of heat of the engine  4  on the fuel pump  81  can be kept to a minimum in comparison with the conventional fuel pump mounting position. Besides, since the distance between the engine  4  and the fuel pump  81  is not too far, the function of the fuel pump  81  to feed fuel to the throttle body  8  is not impaired. Further, since the mounting position of the fuel pump  81  is behind the center frame  30 L, there is no fear of the fuel pump  81  projecting sideways of the vehicle body. 
     Moreover, since the throttle body  8  and the exhaust pipe  50  both connected to the engine  4  are disposed on the right side of the rear suspension damper  80 , it is possible to ensure an optimum layout of the fuel pump  81 , throttle body  8  and exhaust pipe  50  in the vicinity of the center frames  30 R and  30 L. Besides, since the piping space for connection between the fuel pump  81  and the fuel tank  56  and connection between the fuel pump  81  and the throttle body  8  is ensured in such a manner that the fuel supply line becomes short, the fuel pump  81  can fulfill its fuel sucking and delivering function to a satisfactory extent. 
     Further, since the fuel pump  81  is disposed in such a manner that the fuel tank  56  and the throttle body  8  are positioned higher than the fuel pump  81  and since the fuel pipe  59   a  for connection between the fuel pump  81  and the fuel tank  56 , as well as the breather tube  59   b , are connected to the upper end of the fuel pump  81 , it is possible to shorten the distance (fuel supply line) between the fuel tank  56  and the fuel pump  81  and hence possible to shorten the piping. Besides, since the fuel pipe  59   c  for connection between the fuel pump  81  and the throttle body  8  is connected to the upper portion of the fuel pump  81 , it is possible to shorten the distance (fuel supply line) between the fuel pump  81  and the throttle body  8  and hence possible to shorten the piping. Consequently, the fuel pump  81  can fulfill its fuel sucking and delivering function to a satisfactory extent. 
     On the other hand, since the fuel pump  81  is mounted to the center frame  30 L through the bracket  100  and the rubber members  101  and  102  are interposed between the bracket  100  and the fuel pump  81  and between the bracket  100  and the center frame  30 L, vibration on the vehicle body side can be absorbed by the rubber members  101  and  102 . As a result, vibration is no longer propagated to the fuel pump  81  and it is possible to improve the operational reliability of the fuel pump  81 . 
     Moreover, by disposing the fuel pump  81  outside the fuel tank  56 , it is possible to effect storage of a larger amount of fuel. Further, since fuel can be stored also within the fuel tank  81  as an auxiliary tank, a still larger amount of fuel can be stored. 
     Although the best mode for carrying out the present invention has been described above, the present invention is not limited to the above embodiment, but various modifications and changes may be made on the basis of the technical idea of the present invention. 
     Although in the above embodiment the fuel pump  81  is disposed on the left side of the rear suspension damper  80  and intake/exhaust parts are disposed on the right side of the rear suspension damper  80 , a modification may be made so that the fuel pump and the intake/exhaust parts may be disposed on the opposite sides. Also with this structure, the influence of heat of the engine  4  on the fuel pump  81  can be minimized and it is possible to ensure an optimum layout of the fuel pump  81 , throttle body  8  and exhaust pipe  50  in the vicinity of the center frames  30 R and  30 L. 
     Although a specific form of embodiment of the instant invention has been described above and illustrated in the accompanying drawings in order to be more clearly understood, the above description is made by way of example and not as a limitation to the scope of the instant invention. It is contemplated that various modifications apparent to one of ordinary skill in the art could be made without departing from the scope of the invention which is to be determined by the following claims.