Abstract:
A reserve tank layout structure of a motorcycle can secure a capacity of a reserve tank, and allow for easy checking of a remaining amount of a cooling water in the tank from the exterior. The layout structure is provided with a vehicle body frame, an engine supported by the vehicle body frame, a swing arm attached to the vehicle body frame so as to freely oscillate, a rear wheel supported by the swing arm, a wrapping transmission mechanism having an endless rope-like body wound between an output shaft of the engine and an axle of the rear wheel and transmitting power from the output shaft to the axle, and a reserve tank for storing cooling water of the engine, the reserve tank being disposed so that at least a part thereof is positioned at an inner peripheral side of the rope-like body.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a reserve tank layout structure of a motorcycle. 
     2. Description of the Related Art 
     In Japanese Unexamined Patent Publication No. 61-157433, there is disclosed a motorcycle having an engine, a frame mounting the engine thereon, a front fork, a front wheel supported by a front portion of the frame via the front fork, and a rear wheel suspended by a rear portion of the frame. A radiator is arranged in a front side of the engine. A reserve tank is connected to the radiator via piping. The reserve tank is arranged near a meter within a front cowling of the motorcycle (related art 1). 
     Further, there has been conventionally known a motorcycle in which a reserve tank is arranged between a pair of right and left swing arms suspending a rear wheel of the motorcycle (related art 2). 
     In the related art 1 mentioned above, since the reserve tank is arranged near the radiator, there is an advantage that a pipe arrangement structure for connecting the radiator and the reserve tank can be simplified. However, since a space near the meter is narrow, it is hard to secure a capacity of the reserve tank. Further, a technique of the related art 2 can secure a layout space of the reserve tank wider than a technique of the related art 1. However, since the reserve tank gets into an inner side of the swing arm, it is hard to check out a remaining amount of a cooling water in the reserve tank from an external portion of the motorcycle. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the above described condition, and an object of the present invention is to provide a reserve tank layout structure of a motorcycle which can secure a capacity of the reserve tank, and allow a remaining amount of a cooling water in the reserve tank to be easily checked from an external portion of the motorcycle. 
     In accordance with the present invention, there is provided a reserve tank layout structure of a motorcycle, including: a vehicle body frame; an engine supported by the vehicle body frame; a swing arm supporting a rear wheel and attached to the vehicle body frame so as to freely oscillate in a vertical direction; a wrapping transmission mechanism having an endless rope-like body wound between an output shaft of the engine and an axle of the rear wheel and transmitting power from the output shaft to the axle; and a reserve tank for storing engine cooling water, wherein the reserve tank is disposed so that at least a part thereof is positioned at an inner peripheral side of the endless rope-like body. 
     In accordance with this structure, since it is possible to increase a capacity of the reserve tank by utilizing a space in the inner peripheral side of the rope-like body of the wrapping transmission mechanism, and it is possible to arrange the reserve tank in a side portion of the motorcycle provided with the wrapping transmission mechanism, it is possible to easily check out a remaining amount of the cooling water within the reserve tank from an external portion. 
     Preferably, the reserve tank may be attached to the vehicle body frame. 
     In accordance with this structure, since it is possible to make the relative position of a radiator for the engine normally supported on the vehicle body frame and the reserve tank constant, it is possible to simplify a pipe arrangement structure for connecting the radiator and the reserve tank. 
     Preferably, the reserve tank may be attached to the swing arm. 
     In accordance with this structure, since it is possible to make the relative position of the reserve tank and the rope-like body constant, it is not necessary to take into consideration a vertical movement of the rope-like body in accordance with a vertical oscillation of the swing arm, so that it is possible to further increase the capacity of the reserve tank by widely using the inner peripheral side space of the rope-like body. 
     Preferably, the wrapping transmission mechanism may be constituted by a belt transmission mechanism. 
     In accordance with this structure, in the case that the belt transmission mechanism is used as the wrapping transmission mechanism, it is possible to enlarge a diameter of a pulley winding the belt therearound so as to widen the space in the inner peripheral side of the belt, in comparison with the case of using a chain transmission mechanism, so that it is possible to further increase the capacity of the reserve tank. 
     Preferably, a side surface of the reserve tank may be positioned at an outer side from a side surface of the rope-like body in a lateral direction, and is covered by an attachable and detachable cover. 
     Preferably, a display portion for indicating an upper limit and a lower limit of the cooling water may be provided on the side surface of the reserve tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This and other objects and features of the present invention will become more clear from the following description taken in conjunction with a preferred embodiment thereof with reference to the accompanying drawings. 
         FIG. 1  is a left side elevational view showing a main portion of a rear portion of a vehicle body frame in a motorcycle in accordance with a first embodiment of the present invention; 
         FIG. 2  is a schematic view showing a layout of parts in the case of viewing the vehicle body frame from a back side, in the first embodiment; 
         FIG. 3  is a left side elevational view showing a main portion of a rear portion of a vehicle body frame, in a motorcycle in accordance with a second embodiment of the present invention; and 
         FIG. 4  is a schematic view showing a layout of parts in the case of viewing the vehicle body frame from a back side, in the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       FIG. 1  is a left side elevational view showing a main portion of a rear portion of a motorcycle in accordance with a first embodiment of the present invention, and  FIG. 2  is a schematic view showing a layout of parts in the case of viewing the vehicle body frame from behind. The motorcycle in accordance with the present embodiment is of a cruiser type, and a vehicle body frame  10  of the motorcycle has an upper frame  11 , side frames  13 , coupling members  14 , upper and lower cross members  15 A and  15 B, swing arm brackets  16 , lower frames  17 , vertical frames  18 , and rear frames  19 . 
     As shown in  FIGS. 1 and 2 , the upper frame  11  is structured by one element, and extends in an obliquely rearwardly downward direction in an upper portion of the vehicle body frame  10  from a head pipe (not shown). The side frames  13  are provided as a pair of right and left side frames, and extend in an obliquely rearwardly downward direction while being expanded to right and left outer sides from a rear end portion of the upper frame  11 . The coupling members  14  are provided as a pair of right and left coupling members, and extend in obliquely outwardly downward directions from middle portions in a longitudinal direction of the right and left side frames  13 . The upper cross member  15 A extends in a lateral direction of the motorcycle and is connected to lower end portions of the right and left coupling members  14 . The swing arm brackets  16  are provided as a pair of right and left swing arm brackets, and extend to lower sides from respective end portions of the upper cross members  15 A. The lower cross member  15 B is built in lower end portions of the right and left swing arm brackets  16 . The lower frames  17  are provided as a pair of right and left lower frames, extend in a longitudinal direction in the lower portion of the vehicle body frame  10 , and are connected to lower end portions of the respective right and left swing arm brackets  16 . The vertical frames  18  are provided as a pair of right and left vertical frames, and respectively couple rear end portions of the right and left lower frames  17  extending rearwardly from the swing arm bracket  16  to rear end portions of the right and left side frames  13  in a vertical direction. The rear frames  19  are provided as a pair of right and left rear frames, and extend in an obliquely rearwardly upward direction from upper portions of the respective right and left vertical frames  18 . In this case, although an illustration is omitted, a front portion of the lower frame  17  is elongated in an obliquely forward direction so as to be connected to the upper frame  11  or the head pipe. Further, a seat S of the motorcycle shown by a two-dot chain line is arranged in upper portions of the side frames  13  and the rear frames  19 . 
     A swing arm  21  is supported on the swing arm brackets  16  so as to freely oscillate (swing) up and down around a pivot shaft  20  as a supporting point. The swing arm  21  is provided with a pair of right and left plate-like main members  22 , a pair of right and left upper members  23 , a pair of right and left lower members  24  and a pair of right and left coupling members  25 . 
     Each of the right and left main members  22  is formed approximately in a triangular shape in the side view, and is structured such that one apex portion of the triangle is arranged at a front end portion, and the other two apexes of the triangle are arranged at a rear end portion. A pivot tube  27  is built in the apex portions in the front end portions of the right and left main members  22 , and the pivot shaft  20  is inserted in the pivot tube  27 . Cross members  28 A and  28 B are respectively built in upper and lower apex portions in the rear end portions of the right and left main members  22 . 
     As shown in  FIG. 1 , each of the right and left upper members  23  extends in the obliquely rearwardly downward direction from the apex portion at the rear upper side of the main member  22 . Each of the right and left lower members  24  extends in the obliquely rearwardly upward direction from the apex portion at the rear lower side of the main member  22 . The coupling member  25  couples the rear end portion of the upper member  23  and the rear end portion of the lower member  24  to each other, and rotatably supports a rear axle  31  of a rear wheel  30  (shown by the two-dot chain line). 
     An engine  32  shown by a two-dot chain line in  FIG. 1  is arranged in a front side of the swing arm bracket  16  between the upper frame  11  and the lower frame  17 . A power of the engine  32  is transmitted to the rear axle  31  of the rear wheel  30  via a wrapping transmission mechanism  33 . The wrapping transmission mechanism  33  in accordance with the present embodiment corresponds to a belt transmission mechanism, and is constituted by a drive pulley  35  attached to an output shaft  34  of the engine  32 , a driven pulley  36  attached to the rear axle  31  of the rear wheel  30 , and an endless transmission belt (a rope-like body)  37  (shown by a two-dot chain line and partly by a solid line) wound around the drive pulley  35  and the driven pulley  36 . A toothed belt is used as the transmission belt  37 , and toothed pulleys are used as the drive pulley  35  and the driven pulley  36 . As shown in  FIG. 2 , the wrapping transmission mechanism  33  is arranged at a left side portion of the motorcycle. 
     As shown in  FIG. 1 , a radiator apparatus (not shown) is provided in a front side of the engine  32 . A reserve tank  39  for storing cooling water for cooling the engine  32  is connected to the radiator apparatus via piping. The reserve tank  39  is arranged between the side frame  13  and the lower frame  17 , and between the swing arm bracket  16  and the vertical frame  18  as seen from the side. Further, as shown in  FIG. 2 , the reserve tank  39  is arranged on a left side of the left main member  22  of the swing arm  21 . 
     As shown in  FIG. 1 , mounting brackets  40 A and  40 B are provided in the vertical frame  18  and the swing arm bracket  16 . The reserve tank  39  is attached to the mounting brackets  40 A and  40 B via bolts or the like. 
     The reserve tank  39  is formed by a synthetic resin, and is provided with a main body portion  41 , a water supply inlet portion  42  protruding upwardly from an upper surface of the main body portion  41 , and a water outlet portion  43  protruding rearwardly from a lower portion of the main body portion  41 . As shown in  FIG. 2 , the main body portion  41  of the reserve tank  39  is arranged in such a manner that a right side portion  41 A of the reserve tank  39  is set in a space between an upper portion (upper run)  37 A and a lower portion (lower run)  37 B of the transmission belt  37 . A gap t is formed between the reserve tank  39  and the main member  22  of the swing arm  21 . The water supply inlet portion  42  extends upward while being displaced slightly outwardly (leftwardly) in the lateral direction from the main body portion  41 . 
     A range shown by reference symbol BU in  FIG. 2  corresponds to a range in which the upper portion  37 A of the transmission belt  37  moves at a position where the reserve tank  39  is arranged, in accordance with a vertical oscillation of the swing arm  21 , and a range shown by reference symbol BL corresponds to a range in which the lower portion  37 B of the transmission belt  37  moves at the position where the reserve tank  39  is arranged. In this case, as a matter of convenience, the transmission belt  37  is shown by a cross section. The right side portion  41 A of the reserve tank  39  is arranged, in such a manner that it does not overlap the ranges BU and BL, between the bottom of the range BU and the top of the range BL. 
     A lower surface of the right side portion  41 A of the reserve tank  39  set in the space between the upper and lower sides of the transmission belt  37  is arranged in such a manner as to cover the upper side of the lower portion  37 B of the transmission belt  37 . Further, the left side portion  41 B of the reserve tank  39  arranged outwardly (leftwardly) of the transmission belt  37  in the lateral direction bulges further downward than the right side portion  41 A. Accordingly, a step portion (a concave portion)  41 C is formed between the right side portion  41 A and the left side portion  41 B, at the lower surface of the reserve tank  39 . 
     As shown in  FIG. 1 , covers  45  and  46  shown by two-dot chain lines are installed in a space surrounded by the side frame  13 , the lower frame  17 , the swing arm bracket  16  and the vertical frame  18 . The covers  45  and  46  are constituted by a lower cover  45  mainly covering the main body portion  41  of the reserve tank  39 , and an upper cover  46  covering space above that covered by the lower cover  45  in a range including the water supply inlet portion  42  of the reserve tank  39 . The lower cover  45  is fixed to mounting pieces  47  and  48  protruded from the reserve tank  39 , and a mounting bracket  40 C provided in the swing arm bracket  16  by bolts or the like. The upper cover  46  is fixed to a mounting piece  47  protruded from the reserve tank  39 , and a mounting device  49  provided in the vertical frame  18  and the coupling member  14  by bolts. 
     As shown in  FIG. 1 , a display portion  50 A indicating an upper limit and a lower limit of the cooling water is provided in a left side surface of the main body portion  41  of the reserve tank  39 , and the display portion  50 A is exposed to an outer side by detaching the lower cover  45 . As shown in  FIG. 2 , a similar display portion  50 B is provided in a rear surface of the main body portion  41  of the reservoir tank  39 . A notch  51  is formed in a rear surface of the lower cover  45  in such a manner as to expose the display portion  50 B therefrom. 
     (Operation and Effect of First Embodiment) 
     As shown in  FIG. 2 , since the right side portion  41 A of the reserve tank  39  is arranged in the space between the upper portion  37 A and lower portion  37 B (the inner peripheral side) of the transmission belt  37 , and the left side portion  41 B is arranged outwardly of the transmission belt  37  so as to bulge downwardly from the right side portion  41 A, the reserve tank can have a large capacity. 
     Since the belt transmission mechanism is used as the wrapping transmission mechanism  33 , it is possible to make the diameters of the drive pulley  35  and the driven pulley  36  large, it is possible to form the interval between the upper portion  37 A and the lower portion  37 B of the transmission belt  37  wide, and it is possible to easily increase the capacity of the reserve tank  39 . 
     As shown in  FIG. 2 , since the reserve tank  39  is arranged in such a manner as to cover the upper side of the lower portion  37 B of the transmission belt  37 , the reserve tank  39  functions as a cover of the transmission belt  37 , whereby it is possible to prevent soil, mud or the like from biting into the transmission belt  37 . 
     As shown in  FIG. 2 , since the reserve tank  39  is arranged outwardly of the swing arm  21  in the lateral direction, it is possible to easily check out the remaining amount of the cooling water in the reserve tank  39  from the external portion. Particularly, since the display portion  50 B is provided at the rear surface of the main body portion  41  of the reserve tank  39 , and the notch  51  exposing the display portion  50 B therefrom is formed at the rear surface of the lower cover  45 , it is possible to easily check out the display portion  50 B from the rear side even if the lower cover  45  is kept attached. In this case, if the display portion  50 B can be checked out from the rear side, the notch  51  is not necessarily formed in the lower cover  45 . 
     Since the water supply inlet portion  42  of the reserve tank  39  extends upwardly while being displaced outwardly in the lateral direction from the main body portion  41 , it is possible to easily supply the water from the water supply inlet portion  42 . 
     Second Embodiment 
       FIG. 3  is a left side elevational view showing a main portion of a rear portion of a vehicle body frame, in a motorcycle in accordance with a second embodiment of the present invention, and  FIG. 4  is a schematic view showing a layout of parts in the case of viewing the vehicle body frame from a back side, in the second embodiment. The present embodiment is different from the first embodiment in a point that the reserve tank  39  is attached to the swing arm  21 . Since the other structures are the same as the first embodiment, a detailed description thereof will be omitted by attaching the same reference numerals. 
     Specifically, the reserve tank  39  is integrally provided with mounting pieces  53  protruding rearwardly and forwardly, and the mounting pieces  53  are attached to the main member  22  of the swing arm  21  by bolts or the like. As shown in  FIG. 4 , the main body portion  41  of the reserve tank  39  is arranged between the upper portion  37 A and the lower portion  37 B of the transmission belt  37  as seen from behind. The lower surface of the reserve tank  39  covers the lower portion  37 B of the transmission belt  37  from the upper side, and is not provided with the concave (step) portion  41 C ( FIG. 2 ) such as the first embodiment but is formed as a flat surface. 
     In the present embodiment, since the reserve tank  39  is attached to the swing arm  21 , the relative positions of the reserve tank  39  and the transmission belt  37  are fixed. Accordingly, without taking into consideration the movement of the transmission belt  37  in accordance with the up and down oscillation of the swing arm  21  such as in the first embodiment, the capacity of the reserve tank  39  can be increased by widely using the inner peripheral side space of the transmission belt  37 . In particular, it is possible to enlarge the vertical height of the reserve tank  39  in such a manner that the reserve tank  39  comes close to the upper portion  37 A and the lower portion  37 B of the transmission belt  37 . 
     Further, since it is not necessary to form the gap t ( FIG. 2 ) between the reserve tank  39  and the swing arm  21  (as is the case in the first embodiment), and the reserve tank  39  can be brought into contact with or close to the swing arm  21 , it is possible to enlarge the width in the lateral direction of the reserve tank  39 . 
     Other Embodiments 
     The wrapping transmission mechanism  33  may be constituted by a chain transmission mechanism formed by winding an endless chain (a rope-like body) around a drive sprocket and a driven sprocket. 
     The reserve tank  39  is structured such that the right side portion  41 A thereof is arranged in the inner peripheral side of the transmission belt  37 , and the left side portion  41 B is arranged outwardly of the transmission belt  37 . However, the reserve tank  39  may be structured inversely. 
     An entirety of the reserve tank  39  or an entirety of the main body portion  41  may be arranged so as to be located in the inner peripheral side of the transmission belt  37 . 
     Although the invention has been described in its preferred embodiments with a certain degree of particularity, obviously many changes and variations are possible therein. It is therefore to be understood that the present invention may be practical otherwise than as specifically described herein without departing from the scope and spirit thereof.