Abstract:
To ensure that a fuel supply port or hydrogen gas charge port located on the lower side of a seat for a rider in a motorcycle can be opened and closed with less burden. A crosswise groove is provided between a driver&#39;s seat and a pillion of the seat for a rider. The pillion is provided with a longitudinal groove extending in the longitudinal direction of the vehicle body. A charge port is located on the lower side of the crosswise groove. A pad to be fitted in the crosswise groove covers the charge port. An arm as a support member of the pad is contained in the longitudinal groove. In the condition where the arm is set upright and the pad is set upright, the pad is inverted and a cushion part thereof faces forward, thereby providing a backrest for the passenger at the pillion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2007-098812 filed on Apr. 4, 2007 the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a seat for a rider of a motorcycle. More specifically, to a seat for a rider of a motorcycle wherein on a lower side of the seat a fuel supply source such as a fuel cylinder is disposed which can be used for multiple purposes, not only as the seat for a rider. 
     2. Description of Background Art 
     A seat for a rider of a motorcycle is known wherein on the lower side of the seat a fuel supply source such as a fuel cylinder is disposed. For example, Japanese Patent Laid-Open No. 2004-66937 discloses a motorcycle wherein an oil supply port of a fuel tank is disposed on the rear side of a luggage box openable to the upper side, and the upper opening part of the luggage box and the fuel supply port are covered with a seat for a rider capable of opening and closing. See, for example, Japanese Patent Laid-Open No. 2004-66937. 
     A conventional seat for a rider capable of covering simultaneously a luggage box and a fuel supply port is long and comparatively heavy, so that it is necessary to open and close the whole part of the seat for a rider covering a large luggage box aperture even in the case of supplying oil where it suffices to expose only the small oil supply port. In addition, in a motorcycle of the type of having a seat for a rider on the lower side of which only a fuel tank is disposed and no luggage box is provided, the seat for a rider is only opened and closed at the time of supplying fuel. Thus, the opening/closing structure of the seat for a rider is not utilized sufficiently. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     It is an object of an embodiment of the present invention to provide a seat for a rider of a motorcycle wherein only a required minimum part corresponding to a structure disposed on the lower side thereof is configured so that it can be opened and closed and the openable/closable part can be used for multiple purposes. 
     In order to solve the above problems, according to an embodiment of the present invention a seat for a rider of a motorcycle is provided having a fuel supply port disposed on the lower side of the seat for a rider, a pad constituting a part of the seat for a rider is disposed at a position for covering the upper side of the supply port; and the pad is attached to the supply port so as to be capable of being opened and closed. 
     In addition, according to an embodiment of the present invention a seat for a rider of a motorcycle is provided having a fuel supply port disposed on the lower side of the seat for a rider. The seat for a rider includes a pad supported by a support member so as to be displaceable between a position on the upper side of the supply port and a position retracted from the upper-side position so as to open the supply port to the exterior. In addition, the pad and the support member are so disposed so as to sink to the lower side from an upper surface of the seat for a rider when the pad is located in the upper-side position. 
     In addition, according to an embodiment of the present invention the pad is displaceable through swiveling by the support member, and the position of the pad is set so that the pad functions as a backrest for the rider when the support member is set upright. 
     In addition, according to an embodiment of the present invention the support member is pivotally supported on a rear part of a pillion. When the pad is located in the position on the upper side of the supply port, the support member sinks into a longitudinal recess formed in an upper surface of the pillion and the pad sinks into a crosswise recess formed between a driver&#39;s seat and the pillion. 
     Further, according to an embodiment of the present invention the pad has a cushion part, and the pad and the support member are linked to each other so that the cushion part faces upwards when the pad is in the position on the upper side of the supply port, and the cushion part is turned to be displaced to the lower side and to face forwards when the support member is in an upright position. 
     In addition, according to an embodiment of the present invention a seat for a rider of a motorcycle includes a fuel support port disposed on the lower side of the seat for a rider. The seat for a rider includes a pad supported at both left and right ends thereof by a support member so as to be displaceable between a position on the upper side of the supply port and a position retracted from the upper-side position so as to open the supply port to the exterior. The pad is disposed so as to sink to the lower side from an upper surface of the seat for a rider when the pad is located in the upper-side position. 
     Furthermore, according to an embodiment of the present invention the motorcycle is a fuel cell powered vehicle and the supply port is a charge port through which a hydrogen gas reservoir tank is charged with hydrogen gas which is used in a fuel cell. 
     According to an embodiment of the present invention, the fuel supply port located on the lower side of the seat for a rider can be opened and closed by only opening and closing the pad, without displacing the seat for a rider as a whole. 
     According to an embodiment of the present invention, the fuel supply port located on the lower side of the seat for a rider can be covered and be opened to the exterior by only displacing the pad supported by the support member. 
     According to an embodiment of the present invention, the pad is swivelably supported by the support member, and the rider can lean on the pad when the support member is in the upright position. 
     According to an embodiment of the present invention, the fuel supply port on the lower side of the seat for a rider can be covered with the pad when the pad and the support member sink into the recess formed on the seat for a rider. 
     According to an embodiment of the present invention, when the support member is laid flat, the cushion part of the pad faces upwards, which is convenient for providing seating for the rider. When the support member is set upright, the cushion part is turned to face forwards and displaced to the lower side for providing a backrest for the rider. 
     According to an embodiment of the present invention, the support members for supporting the pad are located at both left and right ends of the pad. When the pad is sunken to the lower side from the upper surface of the seat for a rider, the support members at the left and right of the pad can be utilized as left and right extension parts of the seat for a rider, and a wide luggage carrier surface can be secured. 
     According to an embodiment of the present invention, the hydrogen gas charge port located on the lower side of the seat for a rider can be opened and closed by only opening and closing the pad, without displacing the seat for a rider as a whole. 
     According to an embodiment of the present invention, a fuel supply port or a gas charge port can be covered and exposed by only moving up and down the pad which is a part of the seat for a rider, without moving up and down the seat for a rider as a whole, thereby reducing operational labor of a fuel supply. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is an exploded side view of a fuel cell powered motorcycle according to an embodiment of the present invention; 
         FIG. 2  is a plan view of a seat for a rider according to a first embodiment of the present invention; 
         FIG. 3  is a sectional view taken along line A-A of  FIG. 2 ; 
         FIG. 4  is a sectional view taken along line B-B of  FIG. 2 ; 
         FIG. 5  is a perspective view of a seat for a rider in the condition where a charge port cover member is removed; 
         FIG. 6  is a side view of a seat for a rider in the condition where the charge port cover member is used as a backrest for the driver&#39;s seat; 
         FIG. 7  is a plan view of a seat for a rider according to a second embodiment of the present invention; 
         FIG. 8  is a plan view of a seat for a rider according to a modification of the second embodiment of the present invention; 
         FIG. 9  is a plan view of a seat for a rider according to a second modification of the second embodiment of the present invention; 
         FIG. 10  is a side view of the seat for a rider according to the first embodiment, with a helmet fixed thereto; 
         FIGS. 11(   a ) and  11 ( b ) are cross-sectional views of an essential part of the seat for a rider in the preparatory condition for fixation of a helmet; 
         FIG. 12  is a cross-sectional view of an essential part of the seat for a rider after the helmet is fixed; 
         FIG. 13  is a front view of a hook and a hook receiver; 
         FIG. 14  is a front view of the hook and the hook receiver; 
         FIG. 15  is a plan view of a seat for a rider according to a third embodiment of the present invention; and 
         FIG. 16  is a side view of the seat for a rider according to the third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, an embodiment of the present invention will be described below referring to the drawings.  FIG. 1  is an exploded side view of a fuel cell powered motorcycle as an example of a motorcycle having a seat for a rider according to an embodiment of the present invention. The fuel cell powered motorcycle has a fuel generator system including a hydrogen supply system, an oxygen supply system, and a cell stack (inclusive of electrodes, a separator, an electrolyte, etc.), for generating electrical energy through an electrochemical reaction. Herein, the cell stack and a casing (inclusive of members attached to the casing) for containing the same are collectively referred to as a fuel cell. 
     In  FIG. 1 , the fuel cell powered motorcycle  1  has a main frame  3  joined at its front part to a head pipe  2 , a rear frame  4  joined to a rear part of the main frame  3  and extending further rearwardly with a swing unit  5  swingably pivotally supported on a bearing  60  provided on the lower side of a rear part of the main frame  3 . A steering stem (not shown) is turnably supported on the head pipe  2 , and a front fork  7  for supporting a front wheel WF is connected to the lower end of the steering stem. A steering handle  8  is connected to the upper end of the steering stem. A rear shock absorber  9  is connected at its upper end to the main frame  3  and extends towards a skewly rear lower side. The swing unit  5  is connected to the lower end of the rear shock absorber  9 . The swing unit  5  is provided with an electric motor  10  as a prime mover in the motorcycle  1 , and a rear wheel WR is connected to a rear axle  11  driven by the electric motor  10 . A controller, or an ECU  13 , is provided on the upper side of the main frame  3  and the rear frame  4 . A seat for a rider  12  is provided along the rear frame  4  so as to cover the ECU  13 . 
     The main frame  3  is formed to be cradle-like, or cage-like, in overall shape, and a water pump  15 , a supercharger  16 , a humidifier  17 , a fuel cell  18 , and a VCU (voltage control unit)  19  are contained in a space surrounded by the cage-like main frame  3 . More specifically, the water pump  15  is disposed at a front upper part of the inside of the main frame  3 , the supercharger  16  and the humidifier  17  are disposed on the lower side of a central part of the inside, and the VCU  19  is disposed on the upper side of the supercharger  16  and the humidifier  17 . The fuel cell  18  is accommodated on the lower side of the ECU  14  at a rearmost part of the main frame  3 , i.e., at a part just on the front side of the bearing  60 . The fuel cell  18  has a case which has a rectangular shape in side view, and is disposed so that the rectangle is elongate vertically. 
     A catch tank (gas-liquid separator)  20  and a dilution box  21  are provided on the lower side of the fuel cell  18 . In addition, a cooling water radiator  22  for the fuel cell  18  is provided on the front side of the main frame  3 , and an air cleaner  23  is provided so as to surround the upper side of the head pipe  2 . Air introduced into the air cleaner  23  is fed through an air flow sensor  24  into the supercharger  16 , and is supplied through the humidifier  17  to the fuel cell  18 . A pair of hydrogen cylinders  25  are provided as a fuel supply source for supplying hydrogen to the fuel cell  18  and are mounted on the rear frame  4  at left-side and right-side positions. Hydrogen contained in the hydrogen cylinders  25  is subjected to pressure reduction by a regulator, before being supplied to the fuel cell  18 . A pair of batteries (for example, Ni-MH batteries)  26  are provided in a vertically elongate posture respectively on the left and right sides of the front fork  7 . 
     Grab rails  27  are attached to the rear frame  4 . The grab rails  27  are to be used by the passenger (pillion passenger) seated on a rear part of the seat for a rider  12 , to be used when the motorcycle  1  is not running and the driver moves the motorcycle  1  by pushing the motorcycle. The grab rails  27  may be used at the time of operating a stand (not shown) and in like situations. 
     A charge port  25   a  through which to charge the hydrogen cylinder  25  with hydrogen gas is located on the lower side of the seat for a rider  12 . A charge port cover member  29  is provided having a pad  28  capable of covering an upper part of the charge port  25   a  by being located on the upper side of the charge port  25   a . The configurations of the seat for a rider  12  and the charge port cover member  29  will later be described in more details. 
     In the fuel cell  18 , under the function of a fuel electrode (minus electrode), electrons are separated from hydrogen supplied from the hydrogen cylinder  25 , and hydrogen ions produced by separation of electrons migrate through the electrolyte to an air electrode (plus electrode). On the other hand, a circuit is provided to ensure that the electrons separated from hydrogen return to the air electrode, where oxygen in air and the electrons having returned react with each other, to produce water vapor. As a result of this reaction, the electrons continuedly move through an external circuit, and an electric current flows accordingly. The electric power generated in the fuel cell  18  is once stored in the batteries  26 , and is supplied therefrom to the motor  10 . 
       FIG. 2  is a plan view of the seat for a rider  12 ,  FIG. 3  is a sectional view taken along line A-A of  FIG. 2 ,  FIG. 4  is a sectional view taken along line B-B of  FIG. 3 , and  FIG. 5  is a perspective view of the seat for a rider in the condition where the charge port cover member  29  has been removed. In  FIGS. 2-5 , the seat for a rider  12  includes a driver&#39;s seat  12   a  and a passenger&#39;s seat (pillion)  12   b  on the rear side thereof. The pillion  12   b  is provided with a recess  30  such that the charge port cover member  29  can be contained therein. The recess  30  is composed of a crosswise groove  30   a  extending in the width direction of the seat for a rider  12  and a longitudinal groove  30   b  extending rearwards (toward the rear side of the vehicle body) from the crosswise groove  30 . At a rear part position of the pillion  12   b , a cross bar  31  is bridgingly disposed between the rear frames  4 ,  4  on the left and right sides of the vehicle body. The cross bar  31  is provided with a bracket  33  for holding both ends of a pivot  32  for turnably supporting the charge port cover member  29 . 
     The charge port cover member  29  has an arm  34  supported by the pivot  32 , and a pad  28  is attached to the tip of the arm  34 . The arm  34  can be contained in the longitudinal groove  30   b , whereas the pad  28  can be contained in the crosswise groove  30   a . The crosswise groove  30   a  penetrates the seat for a rider  12 , at least at a part where the charge port  25   a  is located on the lower side, so that the charge port  25   a  is visible from the upper side. The crosswise groove  30   a  is formed to penetrate the seat for a rider  12 . In addition, the crosswise groove  30   a  may penetrate the seat for a rider  12  in the thickness direction, not only at the part where the charge port  25   a  is located on the lower side but also in the whole range along the width direction of the seat for a rider  12 . In other words, the driver&#39;s seat  12   a  and the pillion  12   b  may be provided as separate bodies. The charge port  25   a  can be covered with the pad  28  so as to be invisible from the exterior, by containing the charge port cover member  29  in the crosswise groove  30   a.    
     The charge port cover member  29  can be turned about the pivot  32  in the directions indicated by arrows R, between a contained position (substantially horizontal position) where it is contained in the seat for a rider  12  and a non-contained position (substantially vertical position). The pad  28  includes a base part  28   a  which is supported on a shaft  35  so that it can be turned through 180° relative to the arm  34 , and a cushion part  28   b  formed from a material rich in elasticity such as polyurethane foam. In the contained position, the pad  28  is contained in the crosswise groove  30   a , with the cushion part  28   b  facing upwards. On the other hand, in the non-contained position, the cushion part  28   b  can be set to face toward the vehicle body front side, at a position deviated downwards and inverted relative to the arm  34  by turning the cushion part  28   b  through 180° in a counterclockwise direction (in the direction of arrow r) in the  FIG. 3 . With the arm  34  put in the non-contained position, the cushion part  28   b  of the pad  28  thus inverted can be utilized as a backrest for the pillion passenger. 
     In addition, since in the contained position the shaft  35  is disposed nearer to the base of the arm  34  (namely, nearer to the pivot  32 ) in relationship to the pad  28 , the pad  28  naturally starts an inverting motion under gravity during the process of the erection of the arm  34  from the contained position to the non-contained position. The arm  34  can have a stopper  31  a erecting upwards from the bracket  31  on the rear side of the pivot  32  so that the arm  34  will not be tilted toward the vehicle body rear side from the non-contained position. 
     When the motorcycle  1  is operated with the driver and a pillion passenger thereon, the charge port cover member  29  can be utilized as a backrest for the passenger by setting it upright. In addition, when the motorcycle  1  is operated with only the driver thereon, the charge port cover member  29  can be utilized as a waist rest (backrest) for the driver by tilting it up to an arbitrary position between the contained position and the non-contained position. 
       FIG. 6  is a view showing the condition where the charge port cover member  29  is tilted up to the position where it is utilized as the backrest for the rider. In order to hold the charge port cover member  29  in this position, a ratchet mechanism is provided between the pivot  32  and the bracket  33 . In addition, the arm  34  is preferably so configured that it can be extended and contracted for adjustment of the length thereof. In  FIG. 6 , the position of the pad  28  in the condition where the arm  34  is extended is indicated by chain line and denoted by symbol  28 X. 
     As above-mentioned, the charge port cover member  29  functions to cover the hydrogen gas charge port  25   a . In this case, naturally, the charge port cover member  29  can not only cover the charge port  25   a  but also cover other elements arranged within the range which can be covered by the pad  28 . For example, a configuration as shown in  FIG. 2  may be adopted wherein electrical signal input and output ports  36 ,  37  are arranged on the lower side of the passenger&#39;s seat  12  adjacently to the charge port  25   a , and they are kept covered with the pad  28  when not used. The input and output ports  36 ,  37  are, for example, intercom jacks. In the case where a system for communication between the driver and the passenger by utilizing an intercom is mounted on the motorcycle  1 , the jacks have often been arranged on a panel in the vicinity of the steering handle. In the case where the passenger utilizes the jacks arranged on the lower side of the passenger&#39;s seat  12 , the jacks of the intercom, or the input and output ports  36 ,  37 , covered with the pad  28  can be exposed by tilting up the charge port cover member  29 , so that the passenger can connect and disconnect headphone and microphone cords to and from the input and output ports  36 ,  37  by himself, without needing the driver&#39;s help. In addition, there is no need to extend the cords from the pillion  12   b  to the vicinity of the steering handle for communication utilizing the intercom. 
     A second embodiment of the present invention is described below.  FIG. 7  is a plan view of a seat for a rider according to the second embodiment. In the first embodiment above, the charge port cover member  29  was supported on the vehicle body by use of the single arm  34 . However, such a configuration is not limitative, and the pad  28  can be supported as shown in  FIG. 7 . In this embodiment, the pillion seat  12   b  is not provided with any longitudinal groove  30   b , and only a crosswise groove  30   a  for containing the pad  28  is provided between the driver&#39;s seat  12   a  and the pillion  12   b . The pad  28  is supported by two arms  38 ,  39  disposed along left and right edges of a rear part of the seat for a rider  12 . A bearing  41  for supporting a pivot  40  for the arms  38 ,  39  is provided at a rearmost part of the seat for a rider  12 . Rear end parts of the arms  87 ,  39  are pivotally supported by the bearing  41 , and the tips of the arms  38 ,  39  are connected respectively to both left and right ends of the pad  28 . The bearing  41  may be provided with a ratchet mechanism so that the arms  38 ,  39  can be fixed at intermediate positions within a predetermined turning range, in the same manner as in the first embodiment. 
     According to the second embodiment, the bearing  41  is provided at the rearmost part of the seat for a rider  12 . Therefore, when the charge port cover member  29  is set upright, the pillion  12   b  can be used widely, and a wide space for putting luggage can be secured. For example, a helmet can be placed and a chin strap and the like can be fixed to the arms  38 ,  39 . 
     When the charge port cover member  29  is set upright, the pad  28  can be utilized as a backrest at the pillion  12   b . In addition, where the pad  28  of the charge port cover member  29  is contained in the contained position (in the crosswise groove  30   a ), a wider seat inclusive of the arms  38 ,  39  is realized, and the arms  38 ,  39  can be utilized as grips to be gripped by the pillion passenger. 
     Now, a modification of the second embodiment will be described.  FIG. 8  is a plan view of a seat for a rider according to a modification of the second embodiment, and the same symbols as those in  FIG. 7  denote parts which are the same as or equivalent to those described above. In the present embodiment, a plate  42  joined to the arms  38 ,  39  at both ends thereof is provided as a carrier. With the plate  402  thus provided, luggage put on the plate  42  can easily be held stably. 
     In addition, an elastic member, for example, a net formed by knitting rubber strings or the like may be bridgingly disposed between the arms  38 ,  39 , in place of the plate  42 . In this case, the luggage put on the pillion  12   b  is fixed by pressing it from above by the elastic member. 
     Further, a second modification of the second embodiment will be described.  FIG. 9  is a plan view of a seat for a rider according to a second modification of the second embodiment. In this embodiment, a large-width bracket  43  is provided, in place of the arms for supporting the pad  28  of the charge port cover member  29 . The bracket  43  is pivotally supported by a bearing  44  at a rearmost part of the seat for a rider  12 , and the tip of the bracket  43  is connected to the pad  28 . In order that the pillion passenger will not have an uncomfortable feeling, the bracket  43 , at least the upper surface thereof, has a structure wherein the inside is packed with a cushioning material and the outside is covered with a material rich in elasticity, such as rubber, leather, artificial leather, etc. 
     In the second embodiment, there is no need to provide grooves or recesses, such as the longitudinal groove  30   b , for containing the arms  38 ,  39  supporting the pad  28 , and it suffices to provide the crosswise groove  30   a  for containing the pad  28 . In addition, a recess for containing the bracket  43  may be formed in the upper surface of the pillion  12   b  so that the upper surface of the bracket  41  is continuous and flush with the surfaces of left and right end parts of the pillion  12   b.    
     An example of the utilization of the charge port cover member  29 , other than the use as the charge port cover member, will be described below. There are cases where a helmet storing space is needed when the passenger gets off the motorcycle  1 . In the case where a luggage box for storing a bulky thing such as a helmet cannot be provided on the lower side of the seat for a rider  12 , the helmet is often kept hung on a hook formed at a lateral side of the seat for a rider  12 . In this case, however, there is an inconvenience in that the helmet protrudes in the vehicle width direction and rainwater or dust may enter into the helmet, since the helmet may be hung with the of the helmet inside facing upwards. 
     In the present embodiment, it is possible to put the helmet on the seat for a rider  12  and hold the helmet by use of the charge port cover member  29 . 
       FIG. 10  is a side view of the seat for a rider with the helmet fixed thereto. In  FIG. 10 , the helmet  45  is put on the pillion  12   b , and a chin strap  45   a  of the helmet  45  is fixed by hooking it to the arm  34 . 
     Referring to  FIGS. 11(   a ) and  11 ( b ), the method of fixing the helmet  42  is described further. In  FIG. 11(   a ), the chin strap  45   a  of the helmet  45  is hooked by laying it around on the lower side of the arm  34 , and thereafter, as shown in  FIG. 11(   b ), the arm  34  is put into the contained position, namely, contained in a longitudinal groove  30   b . As a result, the chin strap  45   a  is contained in the longitudinal groove  30   b  together with the arm  34 , and the helmet  45  is kept on the seat for a rider  12 . 
       FIG. 12  is a sectional view of an essential part of the seat for a rider  12  with two helmets put thereon. In this example, the helmets  45 ,  46  are put respectively on the driver&#39;s seat  12   a  and the pillion  12   b , and their chin straps  45   a ,  46   a  are fixed by hooking them onto the arm  34 . 
     In addition, in order that the pad  28  is locked to the seat for a rider  12  or to a frame fixed to the seat for a rider  12  when contained in the crosswise groove  30   a , the pad  28  is provided with a hook receiver, whereas a hook for locking with the hook receiver is provided on the side of the seat for a rider  12  or the frame fixed to the seat for a rider  12 . 
       FIGS. 13 and 14  are front views showing a hook and a hook receiver. In  FIG. 13 , the pad  28  is provided with a hook  470  on the lower surface side in the condition where the pad  28  is contained in the crosswise groove  30   a . A hook receiver (catch mechanism)  47  includes a cam plate  472  provided to be turnable about a shaft  471 , a lock lever  474  provided to be turnable about a shaft  473 , and a tension spring  475  for connection between the lower end of the cam plate  472  and one end of the lock lever  47 . Due to the pulling by the tension spring  475 , the cam plate  472  and the lock plate  474  are out of engagement, and the lock lever  474  is in the position of having turned clockwise in  FIG. 13 , whereas the cam plate  472  is in the position of having turned counterclockwise. 
     With the hook  470  pushed down starting from the condition of  FIG. 13 , the tip of the hook  470  abuts on an upwardly facing receiving surface  477  of the cam plate  472 , and turns the cam plate  472  clockwise (see  FIG. 14 ). Then, the other end of the lock lever  474  slides along an edge of the cam plate  472 , and, upon falling to a step  476 , it restrains the cam plate  472  from turning counterclockwise. In this condition, the hook  470  and the cam plate  472  are in engagement with each other, whereby the hook  470  is fixed. 
     In order to unlock the hook  470 , an unlocking cable  478  is connected to the lock lever  474 . With the unlocking cable  478  pulled, the lock lever  474  is turned counterclockwise, the cam plate  472  and the lock lever  474  are disengaged from each other, the cam plate  471  is turned counterclockwise, and the hook  470  and the cam plate  472  are disengaged from each other, resulting in that the pad  28  can be displaced upwards. In addition, as a lock mechanism including a hook and a hook receiver just mentioned above, for example, a known technology such as the one described in Japanese Patent Laid-open No. 2004-99008 can be utilized. 
     Now, a third embodiment of the present invention will be described below. In the third embodiment, an example of a seat for a rider capable of fixing a helmet and capable of playing an antitheft function for the vehicle is shown.  FIG. 15  is a plan view of a seat for a rider according to the third embodiment, and  FIG. 16  is a side sectional view of the same. In  FIGS. 15 and 16 , a pivot  54  extending in the vehicle width direction is disposed between a driver&#39;s seat  12   a  and a pillion  12   b  of the seat for a rider  12 . The pivot  54  is provided on the seat for a rider  12  or on a rear frame  4  for supporting the seat for a rider  12 . A helmet fixing lever  55  is supported on the pivot  54 , and the helmet fixing lever  55  is turned in the vehicle front-rear direction, about the pivot  54 . When in the position of having been turned maximally toward the rear side, the helmet fixing lever  55  is contained in a recess or groove  30  dividing the pillion  12   b  into left and right halves. On the other hand, when in the position of having been turned maximally toward the front side, the helmet fixing lever  55  abuts on the upper surface of the driver&#39;s seat  12   a , when a hook  55   a  formed at the tip of the helmet fixing lever  55  can be engaged with a hook receiver  56  embedded in the driver&#39;s seat  12   a , resulting in a locked condition. As a locking mechanism for the locking between the hook  55   a  and the hook receiver  56 , the one described referring to  FIGS. 13 and 14  can be utilized. 
     With this configuration, the helmets  45 ,  46  can be fixed onto the seat for a rider  12  by a method in which the chin straps  45   a ,  46   a  of the helmets  45 ,  46  are hooked onto the helmet fixing lever  55 , and the helmet fixing lever  55  is turned toward the front side so as to engage the hook  55   a  with the hook receiver  56 . At the time of using the helmets  45 ,  46 , the hook  55   a  and the hook receiver  56  are disengaged from each other by use of a predetermined key, and the helmet fixing lever  55  is lifted up, whereby the chin straps of the helmets  45 ,  46  can be detached from the helmet fixing lever  55 . 
     Thus, the helmets  45 ,  46  fixed to the seat for a rider  12  can be detached from the seat for a rider  12  only in the case where the predetermined key is used, which has an antitheft effect. In addition, if only the helmets  45 ,  46  should be detached without lifting up the helmet fixing lever  55 , the helmet fixing lever  55  remains protruding to the upper side of the driver&#39;s seat  12   a , so that no person can be seated on the driver&#39;s seat  12   a , which has an antitheft effect on the vehicle itself. 
     Further, the chin strap of a helmet is generally provided with a fixture called a “D-ring” or “D-annulus” in view of its appearance. In the case of fixing the charge port cover member  29  having the arm  34  and the pad  28 , the helmet can be fixed onto the seat for a rider  12  by engaging the D-ring directly with the hook receiver  49  provided in the seat for a rider  12 . 
     In addition, the helmet fixing lever  51  can be used as an unlocking lever (lock-in lever) for a main stand storing lock. In general, a motorcycle is provided with a main stand for keeping the motorcycle standing by itself. A system called “lock-in” for locking the main stand so that the motorcycle cannot run is known (refer to Japanese Patent Laid-open No. 2001-213370). As an unlocking lever for the lock-in, the helmet fixing lever  51  is used. When the helmet fixing lever  51  and the main stand storing lock are connected by an unlocking cable and the helmet fixing lever  51  is turned toward the side of the pillion  12   b , the unlocking cable is pulled, the main stand storing lock is unlocked, and the main stand is stored into a predetermined position, resulting in that the motorcycle can run. 
     While the present invention has been described according to the best modes for carrying out the invention, the invention is not limited to the embodiments, and various modifications can naturally be made by those skilled in the art. For example, the invention is not limited to a seat for a rider of a fuel cell powered vehicle, and is applicable also to a seat for a rider of a motorcycle with an internal combustion engine mounted therein and a seat for a rider of a hybrid type motorcycle in which an internal combustion engine and an electric motor are used in combination. In the motorcycle having an internal combustion engine as a prime mover, the hydrogen gas charge port is naturally modified into a supply port for a fuel for the internal combustion engine, such as gasoline. Further, the fuel cells are classified into the direct hydrogen type, the modified fuel type and the like, according to the fuel supply system. Accordingly, the charge port is configured in one of the types suited respectively to hydrogen, methanol, natural gas, gasoline, and so on. Furthermore, even in the direct hydrogen type, a respectively suitable charge port configuration is adopted, according to the form of hydrogen, namely, liquefied hydrogen, occluded hydrogen, and high-pressure gas. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.