Patent Publication Number: US-2020290488-A1

Title: Vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and is a Division of U.S. application Ser. No. 15/836,926 filed on Dec. 11, 2017 which is claiming benefit of U.S. provisional patent application 62/434,419 filed on Dec. 15, 2016, the content of which is hereby incorporated by reference into this application. 
    
    
     FIELD OF THE INVENTION 
     The present specification relates to technologies of four-wheel vehicles. 
     BACKGROUND OF THE INVENTION 
     Some vehicles frequently used in rough terrain include right and left front seats, right and left rear seats, and a cargo bed located rearward of the right and left rear seats. U.S. Pat. No. 8,353,534 discloses a vehicle including rear seats that can fold in the forward direction. As the rear seat is folded forward, the rear surface of the seat back (rear surface of a portion for supporting the rider&#39;s back) of the rear seat becomes the floor of the cargo bed. According to U.S. Pat. No. 8,353,534, folding the rear seats forward increases the capacity of the cargo bed. 
     SUMMARY OF THE INVENTION 
     The structure that allows the rear seats to be folded forward as described in U.S. Pat. No. 8,353,534 requires the seat back to be formed in a rectangular shape in order to employ the seat back as the floor of the cargo bed and thus has a significant restriction on the shape of the rear seat. 
     An object of the present disclosure is to provide a vehicle that enables the cargo bed to have a sufficient capacity while preventing the vehicle body from increasing in size and securing freedom of the shape of the rear seat. 
     (1) An embodiment of a vehicle according to the present disclosure comprises: right and left front wheels; right and left rear wheels; a body frame; right and left front seats mounted on the body frame; a cargo bed located rearward of the right and left front seats; a guide rail disposed on the cargo bed; and a rear seat including a seat frame that is attached on the guide rail and is slidable in a front-rear direction along the guide rail. This embodiment enables the cargo bed to have a sufficient capacity while preventing the vehicle body from increasing in size and securing freedom of the shape of the rear seat. 
     (2) In the embodiment described in (1), the rear seat may include a seat bottom positioned at a bottom of the rear seat and a seat back located on a rear side of the seat bottom, and at least the seat back may be fixed to the seat frame and slidable in the front-rear direction. 
     (3) In the embodiment described in (2), the seat bottom may be movable independently of the seat back. This structure enables the seat back to have an increased movable range. 
     (4) In the embodiment described in (3), the seat bottom may be movable to a laid position at which the seat bottom allows a rider to sit thereon; and the seat bottom may be movable to a standing position at which the seat bottom does not allow the rider to sit thereon. This structure enables the seat back to have an increased movable range. 
     (5) In the embodiment described in (4), when the seat bottom is at the standing position, a seat surface of the seat bottom may face forward. This structure prevents cargo placed in the cargo bed from being in contact with the seat surface of the seat bottom. 
     (6) In the embodiment described in (1), the rear seat may include a seat bottom positioned at a bottom of the rear seat and a seat back located on a rear side of the seat bottom, and the seat bottom may be located in a space defined forward of the cargo bed in a state where the rear seat does not allow a rider to sit thereon. This structure enables the seat back to have an increased movable range. 
     (7) In the embodiment described in (3), the seat bottom may be movable around a pivot shaft so that the seat bottom may be placed in the laid position or the standing position. With this structure, the movement of the seat bottom can be easily made. 
     (8) In the embodiment described in (7), the pivot shaft may be located at a front end of the cargo bed. This structure increases the movable range of the seat back. 
     (9) In the embodiment described in (3), when the seat bottom is in a laid position allowing a rider to sit thereon, the seat bottom may be located on the guide rail. This structure increases the support strength for the seat bottom. 
     (10) In the embodiment described in (2), the seat back may include a back rest portion which is a lower portion of the seat back for supporting a rider&#39;s back, and a head rest portion which is an upper portion of the seat back for supporting the rider&#39;s head, and both of the head rest portion and the back rest portion may be integrally movable in the front-rear direction along the guide rail. 
     (11) In the embodiment described in (1), the rear seat may be movable to a first state in which the rear seat allows a rider to sit thereon and to a second state in which the rear seat does not allow the rider to sit thereon, and when an area in which the seat bottom is located when the rear seat is in the first state is defined as a seat bottom area, at least a part of the seat back may be located in a front part of the seat bottom area in a state where the rear seat is in the second state of the rear seat. This structure enables the cargo bed to have a sufficient area for loading cargo when the rear seat is in the second state. 
     (12) In the embodiment described in (1), the rear seat may include a seat bottom position at a bottom of the rear seat and a seat back located on a rear side of the seat bottom, and a cross portion may be located behind the seat back. With this structure, the seat back may be supported by the cross portion when the seat back is in the usable state. 
     (13) In the embodiment described in (12), the rear seat may be provided with a seat belt mechanism which includes a belt. A guide anchor that guides the belt is attached to the cross portion. This structure eliminates necessity for a dedicated member that supports the guide anchor. 
     (14) In the embodiment described in (1), the rear seat may be provided with a seat belt mechanism including a belt, a joint provided to the belt, and a buckle for the joint to be connected. The cargo bed may have an accommodating portion that accommodates the buckle. This structure prevents the buckle from being an obstacle to cargo placed on the cargo bed. 
     (15) In the embodiment described in (14), the accommodating portion may be concave, and the cargo bed may include a lid for closing the accommodating portion. This structure prevents the buckle from being an obstacle to cargo placed on the cargo bed when the rear seat is in the unusable state. 
     (16) In the embodiment described in (1), the cargo bed may include a cargo bed floor that has a convex portion and a concave portion, each extending in the front-rear direction, and the guide rail may fit into the concave portion or the convex portion. This structure increases the rigidity of the cargo bed floor. Further, this structure prevents the guide rail from being an obstacle to cargo placed in the cargo bed. 
     (17) In the embodiment described in (14), the concave portion and the convex portion extend rearward beyond the guide rail. This structure increases the rigidity of the rear part of the cargo bed. 
     (18) The embodiment described in (1) may further comprise a roll cage covering the front seats and the rear seat. The roll cage may include a portion located further rearward than the rear seat. 
     (19) In the embodiment described in (18), the cargo bed may include a portion located further rearward than the portion of the roll cage. 
     Other objects and features of this invention will be in part apparent and in part point pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings illustrate examples of various components of the invention disclosed herein, and are for illustrative purposes only. 
         FIG. 1  is a side view showing an example of a vehicle of an embodiment according to the present disclosure. 
         FIG. 2  is a rear view of the vehicle. 
         FIG. 3  is a perspective view showing the vehicle frame of the vehicle obliquely viewed from the rear of the vehicle. 
         FIG. 4  is a side view of the vehicle frame of the vehicle. 
         FIG. 5A  is a perspective view of a lower frame (main body frame) constituting the vehicle frame. 
         FIG. 5B  is a perspective view of an upper frame (roll cage) constituting the vehicle frame. 
         FIG. 6  is a side view of the rear seat. In this figure the rear seat is in a usable state. 
         FIG. 7  is a plan view of the cargo bed provided in the rear portion of the vehicle body. In this figure, the rear seats are in the usable state. 
         FIG. 8  is a perspective view showing a structure of the rear seat. In this figure, the seat bottom is arranged in a standing posture. 
         FIG. 9  is a plan view of a frame rear portion constituting the rear part of the lower frame. 
         FIG. 10  is a plan view of the cargo bed. In this figure, the rear seats are arranged in an unusable state. 
         FIG. 11  is a side view of the rear seat. In this figure, the rear seat is in an unusable state. 
         FIG. 12  is a cross-sectional view taken along the line XII-XII indicated in  FIG. 7 . 
         FIG. 13  is a cross-sectional view taken along the line XIII-XIII indicated in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the present invention may be embodied in many different forms, several illustrative embodiments are described herein with the understanding that this disclosure is to be considered as providing examples of the principles of the invention and such examples are not intended to limit the invention to the preferred embodiments described herein and/or illustrated herein. 
     Hereinafter, embodiments according to the present invention will be described. The embodiments disclosed in the present specification should be understood as an example of the invention and the invention is not limited to embodiments described in the following description and in the figures. Other embodiments having advantages that is the same as, or similar to, advantages of the present embodiments are included within the scope of the present invention. 
     Various techniques and structures are described in this specification. Those may be combined with other techniques and structures described herein. Though the present specification does not describe all possible combinations, any combinations are within the scope of the present invention. 
     Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. The terminology used herein is for the purpose of describing particular preferred embodiments only and is not intended to be limiting of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well as the singular forms, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” “comprising” “includes” and “including” when used in this specification, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof. 
       FIG. 1  is a side view of a vehicle  1  which is an example of the embodiments of the present invention.  FIG. 2  is a rear view of the vehicle  1 .  FIG. 3  is a perspective view showing the vehicle  1  obliquely viewed from the rear.  FIG. 4  is a side view of the vehicle frame Fv of the vehicle  1 .  FIG. 5A  is a perspective view of the lower frame  20  constituting a part of the vehicle frame Fv.  FIG. 5B  is a perspective view of an upper frame (roll cage)  30  constituting a part of the vehicle frame Fv.  FIG. 6  is a side view of the rear seat  50 , and  FIG. 7  is a plan view of the cargo bed  40  provided in the rear portion of the vehicle body. In  FIGS. 6 and 7 , the rear seat  50  is in an “usable state”, described later.  FIG. 8  is a perspective view showing a structure of the rear seat  50 . In  FIG. 8 , the seat bottom  52  is arranged at the standing position.  FIG. 9  is a plan view of the frame rear portion  20 R constituting the rear portion of the lower frame  20 .  FIG. 10  is a plan view of the cargo bed  40 , and  FIG. 11  is a side view of the rear seat  50 . In  FIGS. 10 and 11 , the rear seat  50  is arranged in an “unusable state” described later. 
     In the following description, the directions indicated by Y1 and Y2 in those figures will be referred to as a “forward direction” and a “rearward direction”, respectively. The directions indicated by Z1 and Z2 are referred to as an “upward direction” and a “downward direction”, respectively. The directions indicated by X1 and X2 are referred to as a “rightward direction” and a “leftward direction”, respectively. 
     [Outline of Vehicle] 
     The vehicle  1  is a vehicle that is suitable for use on rough terrain and is refereed to as an all terrain vehicle (ATV), a “Side-by-Side vehicle”, an “Utility vehicle”, and a “Recreational Off-Highway vehicle”. As shown in  FIG. 3 , the vehicle  1  includes right and left front wheels  2  and right and left rear wheels  3 . The vehicle  1  includes right and left front seats  4 . A steering wheel  6  for steering the front wheels  2  is located ahead of the left front seat  4  on the left side. The vehicle  1  further includes right and left rear seats  50  located rearward of the front seats  4  and a cargo bed  40  also located rearward of the front seats  4 . As will be explained in detail later, the rear seats  50  in the example of the vehicle  1 , are mounted on the cargo bed  40 . 
     An engine unit  7  (see  FIG. 4 ) including an engine and a transmission is disposed in an almost middle portion of the vehicle body in the front-rear direction. The power of the engine unit  7  is transmitted to both the front wheels  2  and the rear wheels  3 , or to one of the front wheels  2  and the rear wheels  3  through a drive shaft (not shown). In the example of the vehicle  1 , the engine unit  7  is located between the right and left front seats  4 . In the example of the vehicle  1 , the engine unit  7  is located ahead of the cargo bed  40  (in other words, the rear portion  20 R of the vehicle frame Fv to be described later). The arrangement of the engine unit  7  is not limited to the example of the vehicle  1 . 
     [Vehicle Frame] 
     The vehicle  1  includes a vehicle frame Fv. As shown in  FIG. 4 , the vehicle frame Fv includes a lower frame  20  on which the seats  4 ,  50  and the engine unit  7  are mounted. The vehicle frame Fv also includes and an upper frame  30  covering the seats  4  and  50 . The lower frame  20  will be hereinafter referred to as a “main body frame”. The upper frame  30  will be referred to as a “roll cage”. The main body frame  20  and the roll cage  30  are separately formed and connected to each other in the vertical direction by fixing means such as welding or bolts. That is, the main body frame  20  includes a plurality of constituent elements (for example, pipes) each of which is integrally made of a metal. The roll cage  30  includes a plurality of constituent elements (for example, pipes) made of a metal separately from the constituent elements of the main body frame  20 . The constituent elements of the main body frame  20  and the constituent elements of the roll cage  30  are connected to each other by fixing means such as welding or bolts. Note that the phrase “the upper frame  30  covers the seats  4  and  50 ” means that at least a part of the upper frame  30  is positioned above the seats  4  and  50  in a side view, and thus, the upper frame  30  may not overlap with the seats  4  and  50  in a planar view. 
     [Main Body Frame] 
     As shown in  FIG. 4 , the main body frame  20  includes a frame front portion  20 F located between the right and left front wheels  2 . The frame front portion  20 F supports the front wheels  2  through a suspension  8  (see  FIG. 1 ) and through arms (not shown) extending in the right-left direction. The main body frame  20  also includes a frame rear portion  20 R located between the right and left rear wheels  3 . The frame rear portion  20 R also supports the rear wheels  3  through a suspension (not shown) and through arms (not shown) extending in the right-left direction. A cargo bed frame  20 C that is a frame of the cargo bed  40  to be described later is formed on the upper side of the frame rear portion  20 R. The cargo bed frame  20 C protrudes rearward from the frame rear portion  20 R. The main body frame  20  includes a frame middle portion  20 M located between the frame front portion  20 F and the frame rear portion  20 R. The frame middle portion  20 M has the engine unit  7  and the front seats  4  mounted thereon. 
     As shown in  FIG. 5A , in the example of the vehicle  1 , the frame middle portion  20 M includes extending portions  21  on its right and left portions. The extending portion  21  includes, in the middle frame portion  20 M, a middle portion  21 B extending in the front-rear direction, a front vertical portion  21 A extending obliquely upward from the front portion of the middle portion  21 B, and a rear vertical portion  21 C extending obliquely upward from the rear portion of the middle portion  21 . The extending portion  21  includes, in the frame middle portion  20 M, a middle vertical portion  21 F extending upward from the mid portion of the middle portion  21 B. Additionally, the extending portion  21  includes a side wall extending portion  21 D extending rearward from an upper portion of the rear vertical portion  21 C. The side wall extending portion  21 D constitutes the side wall  41  (see  FIG. 3 ) of the cargo bed  40 . Further, the extending portion  21  has a cargo bed vertically extending portion  21 E extending upward from the side wall extending portion  21 D. Each portion of the extending portion  21  is formed of a pipe, for example, but it is not necessarily limited thereto. The extending portion  21  may be an integrally formed member, or the extending portion  21  may be constituted by plural members (for example, pipes) connected to each other. For example, the middle portion  21 B and the front vertical portion  21 A may be one pipe integrally formed, the rear vertical portion  21 C and the side wall extending portion  21 D may be one pipe integrally formed, and the two pipes are connected to each other by fixing means such as such as welding or bolts. 
     In the example of the vehicle  1 , as shown in  FIG. 5A , the frame middle portion  20 M includes a bottom  23  between the right and left middle portions  21 B. The bottom  23  includes, for example, a bottom panel  23   a , members  23   b  extending in the right-left direction and joined to the bottom panel  23   a , members  23   c  extending in the front-rear direction and joined to the bottom panel  23   a . The right and left middle portions  21 B are joined (for example, welded) to the left and right edges of the bottom  23 , respectively. The engine unit  7  and the front seat  4  are supported by the bottom  23 . Also, plural cross portions  22 A,  22 B,  22 C extend between the right and left extending portions  21 . The structure of the main body frame  20  and the shape of each portion are not limited to the example in the vehicle  1 . For example, the bottom  23  of the main body frame  20  does not necessarily include the bottom panel  23   a.    
     [Roll Cage] 
     As shown in  FIG. 5B , the roll cage  30  includes right and left front vertically extending portions  31 A, right and left upper extending portions  31 B, right and left rear vertically extending portions  31 C, and right and left middle vertically extending portions  31 D (See  FIG. 5 ). As shown in  FIG. 4 , the front vertically extending portion  31 A is located forward of the front seat  4  in a side view of the vehicle body and extends in the vertical direction. Specifically, in the example of the vehicle  1 , the front vertically extending portion  31 A extends obliquely rearward and upward. The front vertically extending portion  31 A is connected to the front vertical portion  21 A of the main body frame  20  by fixing members such as bolts. The upper extending portion  31 B is located above the seats  4  and  50  in a side view of the vehicle body and extends in the front-rear direction. The rear vertically extending portion  31 C extends downward from the rear portion of the upper extending portion  31 B and is located rearward of at least the front seat  4 . In the example of the vehicle  1 , the rear vertically extending portion  31 C is located slightly rearward of the rear seat  50 . The rear vertically extending portion  31 C may overlap the rear seat  50  (more specifically, the seat back  51  described later) in a side view of the vehicle body. The rear vertically extending portion  31 C in the example of the vehicle  1  is arranged in the vertical direction in general, but it may be inclined in a forward or backward direction. The rear vertically extending portion  31 C is connected to the cargo bed vertically extending portion  21 E of the cargo bed frame  20 C, for example, by fixing members such as bolts. The right and left rear vertically extending portions  31 C are apart from each other in the right-left direction and thus users can load and unload cargo into the cargo bed  40  through the opening caused between the right and left rear vertically extending portions  31 C. 
     The middle vertically extending portion  31 D extends downward from a mid portion of the upper extending portion  31 B and is located between the front vertically extending portion  31 A and the rear vertically extending portion  31 C in a side view of the vehicle body. In the example of the vehicle  1 , the middle vertically extending portion  31 D overlaps the front seat  4  (more specifically, the seat back  4   a  of the front seat  4 ) in a side view of the vehicle body (see  FIG. 1 ). The middle vertically extending portion  31 D may be located slightly rearward of the front seat  4 . The middle vertically extending portion  31 D is connected to the middle vertical portion  21 F of the main body frame  20  by fixing members such as bolts, for example. 
     As shown in  FIG. 5B , the roll cage  30  also includes a plurality of cross portions  32 A to  32 E extending in the right-left direction to connect the right and left extending portions  31 A to  31 D. In the example of the vehicle  1 , three cross portions  32 A,  32 B,  32 C extend between right and left upper extending portions  31 B. A cross portion  32 D extends between the right and left rear vertically extending portions  31 C. Further, a cross portion  32 E extends between the right and left middle vertically extending portions  31 D. The cross portions  32 D and  32 E will be described later in detail. As shown in  FIG. 1 , a roof  11  is attached to the roll cage  30  to cover the seats  4  and  50 . In detail, the roof  11  is attached to, for example, the right and left upper extending portions  31 B and the cross portions  32 A,  32 B, and  32 C, connected to the upper extending portions  31 B. The roof  11  is made of resin, for example. 
     In the example of the vehicle  1 , the cross portions  32 A to  32 E are formed separately from one another, and both ends of each cross portion  32 A to  32 E are connected to the extending portions  31 A to  31 D by fixing means such as welding or bolt. The connection structure of portions of the roll cage  30  may be changed. For example, the right and left front vertically extending portions  31 A and the front cross portion  32 A may be integrally formed of single pipe-like member. The right and left middle vertically extending portions  31 D and the central cross portion  32 B may be integrally formed of single pipe-like member. Further, the right and left rear vertically extending portions  31 C and the rear cross portion  32 C may be integrally formed of single pipe-like member. 
     [Cargo Bed] 
     As shown in  FIG. 3 , the vehicle  1  includes a cargo bed  40  at the rear portion thereof. The cargo bed  40  includes a cargo bed floor  43  (see  FIG. 7 ) on which cargo is placed. The cargo bed  40  also includes side walls  41  located on the right and left sides of the cargo bed floor  43  and a rear wall  42  located at the rear edge of the cargo bed floor  43 . 
     The lower portion of the rear vertically extending portion  31 C of the roll cage  30  is connected to the cargo bed frame  20 C constituting the cargo bed  40 . The cargo bed frame  20 C includes the side wall extending portions  21 D and the cargo bed vertically extending portions  21 E described above. As shown in  FIGS. 1 and 7 , the cargo bed floor  43  of the cargo bed  40  includes an area A 1  extending forward beyond the plane P 1  defined by the right and left rear vertically extending portions  31 C (in other words, the plane P 1  is defined as a plane parallel to the right-left direction of the vehicle body and passing through the right and left rear vertically extending portions  31 C.). In the example of the vehicle  1 , the cargo bed frame  20 C includes the cargo bed vertically extending portion  21 E extending upward from the side wall extending portion  21 D to connect to the rear vertically extending portion  31 C of the roll cage  30 . The area A 1  of the cargo bed floor  43  is located further forward than the connection portion between the side wall extending portion  21 D and the cargo bed vertically extending portion  21 E of the cargo bed frame  20 C in a side view of the vehicle body. The connection structure between the cargo bed frame  20 C and the roll cage  30  is not limited to the example of the vehicle  1 . For example, the lower portion of the rear vertically extending portion  31 C of the roll cage  30  may be directly connected to the side wall extending portion  21 D of the cargo bed frame  20 C. 
     In the example of the vehicle  1 , the right and left rear seats  50  are disposed on the cargo bed floor  43 . The rear seat  50  includes a seat bottom  52  (see  FIG. 7 ) located in the lower part of the rear seat  50  and including an upper surface for the rider to sit on, and a seat back  51  standing on the rear side of the seat bottom  52  and including a front surface for supporting the back of the rider. The seat bottom  52  is disposed in the area A 1  of the cargo bed floor  43  in a plan view of the vehicle body. The front edge of the seat bottom  52  is located along the front edge  43   a  of the cargo bed floor  43  in a plan view of the vehicle body. The front edge of the seat bottom  52  may be located slightly forward of the front edge  43   a  of the cargo bed floor  43 , and alternatively may be located slightly rearward of the front edge  43   a  of the cargo bed floor  43 . In other words, the entire seat bottom  52  may be located on the cargo bed floor  43 , and alternatively only a part of the seat bottom  52  may be located within the area A 1  of the cargo bed floor  43 . 
     The rear seat  50  is configured to be movable so as to expand the capacity of the cargo bed  40 . That is, the cargo bed floor  43  includes an area in which the seat bottom  52  is located (an area covered by the seat bottom  52 ) when the rear seat  50  is in its usable state. The rear seat  50  is configured to recede from at least a part of the area. As will be described later, in the example of the vehicle  1 , guide rails  44  extending in the front-rear direction are attached to the area A 1  of the cargo bed floor  43  (see  FIG. 10 ). The rear seat  50  (in more detail, the seat back  51 ) is slidable in the front-rear direction along the guide rails  44 . The forward slide of the rear seat  50  increases the capacity of the cargo bed  40 . The movement mode of the rear seat  50  is not limited to the example in the vehicle  1 . For example, the seat back  51  of the rear seat  50  may be configured to be movable toward the side wall  41  of the cargo bed  40 . In other words, the seat back  51  may be turnable toward the side wall  41  of the cargo bed  40 . In yet another example, the seat back  51  may be foldable in a forward direction. 
     As shown in  FIG. 7 , the cargo bed floor  43  includes an area A 2  formed behind the area A 1 . That is, the cargo bed floor  43  includes an area A 2  located rearward of the plane P 1  defined by the rear vertically extending portions  31 C of the roll cage  30  (hereinafter, the area A 1  is referred to as a “front area” and the area A 2  is referred to as a “rear area”). In the example of the vehicle  1 , the rear area A 2  is located further rearward than the cross portion  32 D extending between the right and left rear vertically extending portions  31 C in a plan view of the vehicle body. Also, the rear area A 2  is located further rearward than the rear seats  50  in a plan view of the vehicle body. More specifically, the rear area A 2  is located further rearward than the rear end (upper end) of the seat backs  51  in the plan view of the vehicle body. Unlike the example of the vehicle  1 , a part of the rear area A 2  may overlap the seat backs  51 . 
     As shown in  FIG. 7 , the right and left rear seats  50  are located apart from each other in the right-left direction. Therefore, the front area A 1  includes an area A 3  defined between the right and left rear seats  50  (hereinafter this area A 3  will be referred to as the “middle area”). 
     The front area A 1  (including the middle area A 3 ) and the rear area A 2  are located at the same height. Therefore, when a rear seat  50  is moved, the front area A 1  and the rear area A 2  can be used effectively. In other words, the structure facilitates easily placing cargo on the cargo bed  40 . The height of front area A 1  and the height of rear area A 2  are different. 
     [Cargo Bed Frame] 
     As described above, the main body frame  20  includes the frame rear portion  20 R connected with arms and a suspension for supporting the rear wheels  3 . In the example of the vehicle  1 , the cargo bed frame  20 C (see  FIG. 4 ) is formed on the upper side of the frame rear portion  20 R. A floor panel  43 F (see  FIG. 6 ) constituting the cargo bed floor  43  is fixed to the upper side of the cargo bed frame  20 C. The floor panel  43 F covers the entire cargo bed frame  20 C. The cargo bed frame  20 C is located above the rear wheel  3  in a side view of the vehicle body (see  FIG. 1 ). 
     As shown in  FIG. 5A , in the example of the vehicle  1 , the cargo bed frame  20 C includes a plurality of floor support portions  24  extending linearly in the front-rear direction. The cargo bed frame  20 C includes a plurality of cross portions  22 B,  22 C,  22 E and  22 D extending in the right-left direction and fixed to the floor support portions  24 . Hereinafter, these cross portions  22 B,  22 C,  22 E and  22 D will be referred to as “floor cross portions”. In an example, the plurality of floor cross portions  22 B,  22 C,  22 E,  22 D are fixed on the upper side the floor support portion  24 , and the floor panel  43 F is fixed on the floor cross portions  22 B,  22 C,  22 E,  22 D. The floor cross portions  22 B,  22 C,  22 E,  22 D are located at the same height. Thus, the height in an area of the cargo bed floor  43  where the rear seat  50  is disposed and the height in an area of the cargo bed floor  43  behind the area where the rear seat  50  is disposed are the same. That is, the entire cargo bed floor  43  has the same height. 
     The floor cross portion  22 B is located at the front end of the cargo bed floor  43  and the floor cross portion  22 C is located at the rear end of the cargo bed floor  43 . The floor cross portions  22 E,  22 D are arranged between the floor cross portion  22 B and the floor cross portion  22 C. The guide rails  44  of the rear seat  50  are supported, for example, by the floor cross portion  22 B located at the front end and the floor cross portion  22 D located between the floor cross portions  22 B and  22 C (see  FIG. 9 ). 
     As shown in  FIG. 5A , in the example of the vehicle  1 , the floor cross portion  22 B at the front end extends between the right and left rear vertical portions  21 C of the main body frame  20  and fixed to the front ends of the floor support portions  24 . The cargo bed frame  20 C includes rear end members  21 G fixed to the rear ends of the side wall extending portions  21 D constituting the side wall  41  of the cargo bed  40  and extending in the vertical direction. The floor cross portion  22 C at the rear end extends between the right and left rear end members  21 G and is fixed to the rear ends of the floor support portions  24 . The structure of the cargo bed frame  20 C is not limited to the example of the vehicle  1  and may be changed. For example, the floor support portions extending in the front-rear direction may be fixed on the upper side of the plurality of floor cross portions. In addition, the floor panel  43 F may be fixed to the floor support portions. 
     [Rear Cross Portion of Roll Cage] 
     As described above, both end portions  32   c  of the cross portion  32 D located at the rear end of the roll cage  30  are connected to the right and left rear vertically extending portions  31 C. As shown in  FIG. 2 , the cross portion  32 D is formed such that its middle portion  32   a  is positioned higher than the end portions  32   c . When an operator puts cargo onto the front area A 1  located forward of the plane P 1 , the structure described above prevents the cross portion  32 D from being an obstruction. 
     As described above, in the example of the vehicle  1 , the right and left rear seats  50  are apart from each other in the right-left direction, and the middle area A 3  (see  FIG. 7 ) for cargo is secured between the right and left rear seats  50 . In detail, the middle area A 3  is secured between the right and left seat bottoms  52 . The middle area A 3  located forward of the middle portion  32   a  of the cross portion  32 D in a plan view of the vehicle body. Since the middle portion  32   a  of the cross portion  32 D is higher than the end portions  32   c , the cross portion  32 D is prevented from being an obstruction when an operator puts cargo onto the middle area A 3 . 
     As shown in  FIG. 2 , in the example of the vehicle  1 , the cross portion  32 D includes lateral portions  32   b  located behind the seat backs  51  of the right and left rear seats  50 . This allows the seat back  51  to be supported by the lateral portion  32   b . For example, when a force acts on the seat back  51  in the front-rear direction during running of the vehicle, the lateral portion  32   b  prevents the seat back  51  from being greatly inclined rearward. In a normal state in which no backward force is applied to the seat back  51 , a clearance may be secured between the lateral portion  32   b  and the seat back  51 , or alternatively the lateral portion  32   b  may be in contact with the seat back  51 . 
     In the example of the vehicle  1 , the seat back  51  is configured to support the rear side of the head of the rider. That is, as shown in  FIG. 2 , the seat back  51  includes a lower portion  51   a  that supports the back of a rider and an upper portion  51   b  having a smaller width in the right-left direction than the lower portion  51   a  (hereinafter, the lower portion  51   a  is referred to as a “back rest portion”, and the upper portion  51   b  is referred to as a “head rest”.). The head of the rider can be supported by the head rest  51   b . The lateral portion  32   b  of the cross portion  32 D is located behind the head rest  51   b  of the seat back  51 . Therefore, the lateral portion  32   b  of the cross portion  32 D is positioned high, and thus when an operator puts cargo onto the rear side of the rear seat  50 , the cross portion  32 D is prevented from being an obstruction. 
     As shown in  FIG. 2 , the middle portion  32   a  of the cross portion  32 D is located higher than the lateral portions  32   b . The middle portion  32   a  of the cross portion  32 D is located between the right and left seat backs  51  in the rear view of the vehicle body. In the example of the vehicle  1 , the middle portion  32   a  linearly extends in the right-left direction in a rear view of the vehicle body. This shape of the cross portion  32 D effectively prevents the cross portion  32 D from being an obstacle when putting cargo onto the area between the right and left rear seats  50 . 
     As shown in  FIG. 2 , the end portions  32   c  of the cross portion  32 D are positioned higher than the back rest portion  51   a . Therefore, the cross portion  32 D is prevented from being an obstacle when an operator puts cargo onto the rear side of the seat  50 . As described above, in the example of the vehicle  1 , the rear seats  50  are configured to be slidable in a forward direction. Therefore, the cross portion  32 D is prevented from being an obstacle when an operator puts cargo onto an area formed by sliding the rear seats  50 . 
     The lateral portion  32   b  of the cross portion  32 D linearly extends in the right-left direction in the rear view of the vehicle body. According to this shape of the cross portion  32 D, a force equally acts from the seat back  51  to the lateral portion  32   b  and thus the seat back  51  can be stably supported by the lateral portion  32   b . As described here, the cross portion  32 D in the example of the vehicle  1  includes the lateral portions  32   b  linearly extending in the right-left direction and the middle portion  32   a  linearly extending in the right-left direction. The end of the lateral portion  32   b  is bent up toward the middle portion  32   a.    
     The shape and the position of the cross portion  32 D is not limited to the example in the vehicle  1 . For example, the lateral portions  32   b  and the middle portion  32   a  may not extend linearly. That is, the whole of the cross portion  32 D may be curved such that the middle portion  32   a  is positioned higher than the end portion  32   c . Also, the lateral portion  32   b  and the end portion  32   c  of the cross portion  32 D may be located behind the back rest portion  51   a.    
     [Front Cross Portion of Roll Cage] 
     As shown in  FIG. 5B , the roll cage  30  includes a cross portion  32 E located forward of the cross portion  32 D and lower than the cross portion  32 D. In the example of the vehicle  1 , both ends  32   e  of the cross portion  32 E are connected to the right and left middle vertically extending portion  31 D. The cross portion  32 E improves the rigidity of the roll cage  30 . 
     As shown in  FIG. 3 , the cross portion  32 E is located behind the right and left front seats  4 . More specifically, the cross portion  32 E includes lateral portions  32   f  located behind the seat backs  4   a  of the right and left front seats  4 . The seat back  4   a  is supported by the lateral portion  32   f . For example, when a force acts on the seat back  4   a  in the front-rear direction during running of the vehicle, the lateral portion  32   f  prevents the seat back  4   a  from being reclined greatly. In the normal state in which the rearward force is not applied to the seat back  4   a , a clearance may be made between the lateral portion  32   f  and the seat back  4   a , or alternatively the lateral portion  32   f  may be in contact with the seat back  4   a.    
     As shown in  FIG. 2 , the middle portion  32   g , of the cross portion  32 E located behind the front seat  4 , is positioned between the right and left front seats  4  in the rear view of the vehicle. The middle portion  32   g  is located at a different height than the end portions  32   e  of the cross portion  32 E. In more detail, the middle portion  32   g  is located at a different height than the lateral portions  32   f . This prevents the middle portion  32   g  of the cross portion  32 E from being an obstacle to a field of view of a rider sitting on the rear seat  50 . In the example of the vehicle  1 , the middle portion  32   g  is located lower than the lateral portion  32   f . Unlike the example of the vehicle  1 , the middle portion  32   g  of the cross portion  32 E may be located higher than the lateral portion  32   f , similar to the middle portion  32   a  of the cross portion  32 D located behind the rear seats  50 . 
     As shown in  FIG. 5B , in the example of the vehicle  1 , the roll cage  30  includes a grab bar  34  located under the cross portion  32 E and connected to the right and left middle vertically extending portions  31 D. A rider sitting on the rear seat  50  may grab the grab bar  34 . In the example of the vehicle  1 , the middle portion of the grab bar  34  is located under the middle portion  32   g  of the cross portion  32  E and is fixed to the middle portion  32   g  of the cross portion  32 E. According to this structure, the grab bar  34  can be reinforced by the cross portion  32 E even when a member having a lower rigidity than the cross portion  32 E (for example, a member thinner than the cross portion  32 E) is used as the grab bar  34 . The grab bar  34  is located below the lateral portions  32   f  of the cross portion  32 E. The structure of the grab bar  34  and the cross portion  32 E is not limited to the example above, of the vehicle  1 . In another example, the grab bar  34  is not necessarily fixed to the cross portion  32 E. In yet another example, the roll cage  30  does not necessarily include the grab bar  34 . 
     [Connection Between Cargo Bed Frame and Roll Cage] 
     The main body frame  20  includes the rear vertical portions  21 C (see  FIG. 5A ) extending obliquely rearward and upward from the rear portion of the middle portion  21 B of the frame middle portion  20 M. As shown in  FIG. 1 , in the example of the vehicle  1 , the rear vertically extending portion  31 C of the roll cage  30  is located further rearward than the upper portion of the rear vertical portion  21 C of the main body frame  20 . In other words, the rear vertically extending portion  31 C of the roll cage  30  is located rearward of the front end of the side wall extending portion  21 D constituting the side wall  41  of the cargo bed  40 . The arrangement of the rear vertically extending portion  31 C makes the rear vertically extending portion  31 C closer to a vertical orientation as compared with an arrangement in which the rear vertically extending portion  31 C is connected to the rear vertical portion  21 C. As a result, the vertical force tends to act axially on the rear vertically extending portion  31 C. When the rear seat  50  is slid forward, the seat back  51  is located forward, away from the rear vertically extending portion  31 C in a side view of the vehicle body. As shown in  FIG. 1 , the vehicle  1  may be provided with a side guard  12  located on the lateral side of the rear seats  50 . 
     As shown in  FIG. 4 , the cargo bed frame  20 C protrudes rearward from the frame rear portion  20 R supporting the rear wheels  3 . As shown in  FIG. 6 , the rear vertically extending portion  31 C of the roll cage  30  is connected to the cargo bed frame  20 C at a position forward of the rear end of the cargo bed frame  20 C. In the example of the vehicle  1 , the rear vertically extending portion  31 C of the roll cage  30  is connected to the cargo bed frame  20 C at a position forward of the rear end of the floor support portion  24  supporting the cargo bed floor  43 . Thus, the rear vertically extending portion  31 C and the frame rear portion  20 R are close to each other in the front-rear direction. That increases the strength of the cargo bed frame  20 C with respect to the vertical force acting on the roll cage  30 . Also, since the rear vertically extending portion  31 C of the roll cage  30  is connected to the cargo bed frame  20 C at a position forward of the rear end of the floor support portion  24 , the rear area A 2  located behind the plane P 1  described above is surly secured in the cargo bed floor  43 . 
     In the example of the vehicle  1 , the cargo bed frame  20 C includes a cargo bed vertically extending portion  21 E located further forward than the rear end of the floor support portion  24  and extends upward from the side wall extending portion  21 D. The rear vertically extending portion  31 C of the roll cage  30  is connected to the cargo bed vertically extending portion  21 E. The connecting structure between the cargo bed frame  20 C and the rear vertically extending portion  31 C of the roll cage  30  is not limited to the example of the vehicle  1 . For example, the rear vertically extending portion  31 C may be directly connected to the side wall extending portion  21 D. 
     As shown in  FIG. 6 , in the example of the vehicle  1 , the cargo bed frame  20 C includes rear end members  21 G at the rear ends thereof. The rear end member  21 G extends in the vertical direction and connects the rear end of the side wall extending portion  21 D, the cargo bed vertically extending portion  21 E, and the floor support portion  24 . This structure improves, for example, the strength of the rear portion of the cargo bed frame  20 C. As shown in  FIG. 6 , the rear end member  21 G is provided with a rear wall support portion  21 H further protruding rearward from the rear end member  21 G. The right end and the left ends of the rear wall  42  of the cargo bed  40  are fixed to the rear wall support portions  21 H, respectively. Therefore, the rear wall  42  is located further rearward than the cargo bed vertically extending portion  21 E of the cargo bed frame  20 C or the rear vertically extending portion  31 C of the roll cage  30 . As a result, the capacity of cargo bed  40  can be increased. 
     [Rear Seat] 
     The rear seat  50  is movable to a state in which the rider is allowed to sit on the rear seat  50  and a state in which the rider is not allowed to sit thereon. In the following description, the state in which the rider is allowed to sit on the rear seat  50  is referred to as the “usable state”, and the state in which the rider is not allowed to sit thereon is referred to as the “unusable state”. When the rear seat  50  is in the “usable state”, as shown in  FIG. 6 , the seat bottom  52  is located on the cargo bed floor  43 , the seat surface  52   a  of the seat bottom  52  faces upward, and the seat back  51  is located in a standing position on the rear side of the seat bottom  52 . The “unusable state” means a state in which at least one of the position and the orientation of the seat bottom  52  changes from the position and the orientation thereof in the usable state and the seat back  51  moves forward so that the rider is not allowed to sit on the rear seat  50 . In the example of the vehicle  1 , when the area in which the seat bottom  52  of the rear seat  50  in the usable state is disposed is defined as a seat bottom area A 4  (see  FIG. 6 ), the lower end L of the seat back  51  (in other words, the lower end of the seat frame  53  to be described later) moves to a front portion of the seat bottom area A 4  when the rear seat  50  is in the unusable state (see  FIG. 11 ). 
     As shown in  FIG. 10 , the cargo bed floor  43  is provided with guide rails  44 . In the example of the vehicle  1 , the guide rails  44  are disposed on the floor panel  43 F constituting the cargo bed floor  43 . The guide rails  44  are then fixed to the cargo bed frame  20 C located below the floor panel  43 F by fixing members such as screws or bolts. In the example of the vehicle  1 , two guide rails  44  are arranged in parallel for each rear seat  50 . As shown in  FIG. 8 , the rear seat  50  includes the seat frame  53  attached to the guide rails  44 . The seat frame  53  is slidable in the front-rear direction along the guide rails  44  (see  FIG. 10 ). In the example of the vehicle  1 , the seat frame  53  includes the guided portions  53   b ,  53   c  mounted on the guide rail  44  and slidable along the guide rails  44 . The guided portion  53   b  is located outside the guide rails  44 . 
     As shown in  FIG. 8 , in the example of the vehicle  1 , the seat frame  53  is fixed to the seat back  51 . Therefore, the seat back  51  is allowed to move in the front-rear direction. Specifically, the seat back  51  is allowed to translate in the front-rear direction. This can increase the capacity of the cargo bed  40  while preventing the vehicle from becoming larger in the front-rear direction. That is, the forward movement of the seat back  51  places the rear seat  50  in the unusable state and enlarges the rear cargo area of the rear seat  50 . In the example of the vehicle  1 , the seat frame  53  includes a support rod  53   a  extending upwardly from the guided portions  53   b ,  53   c  and fixed to the seat back  51 . The support rod  53   a  is fixed to the back of the seat back  51 , for example. Further, as shown in  FIG. 8 , the support rod  53   a  may be connected to the right and left guided portions  53   b  and  53   c . The structure of the seat frame  53  and the fixing structure between the seat frame  53  and the seat back  51  are not limited to the example shown for the vehicle  1  and may be changed. 
     As shown in  FIG. 8 , in the example of the vehicle  1 , the seat bottom  52  is not fixed to the seat frame  53  and thus is configured to move independently of the seat back  51 . In the example of the vehicle  1 , the seat bottom  52  is laid on the guide rail  44  when the rear seat  50  is in the usable state (see  FIG. 6 ) and is in a standing position when the rear seat  50  is in the unusable state (see  FIGS. 8 and 11 ). Unlike the example of the vehicle  1 , the seat bottom  52  may also be configured to be slidable in the front-rear direction together with the seat back  51 . In this case, the seat frame  53  may be fixed to the seat bottom  52 . In yet another example, the seat frame  53  may be fixed to the seat back  51  and the seat bottom  52  may be fixed to the seat back  51 . 
     A conventional structure that the rear seat is foldable and the folded seat back is used as the cargo bed floor reduces the freedom in the shape and the size of the seat back. Specifically, in this structure, the seat back needs to be rectangular, limiting space for a head rest. The structure in vehicle  1  in which the forward movement of the seat back  51  expands the capacity of the cargo bed  40  can increase the freedom of the shape and the size of the seat back  51 . In the example of the vehicle  1 , the seat back  51  includes, in the upper part of the seat back  51 , the head rest  51   b  having a smaller width than that of the back rest portion  51   a . In addition, the seat back  51  is curved such that the edge portions  51   e  in the right-left direction are located further forward than the middle portion  51   f . The seat frame  53  is fixed, for example, to the back of the middle portion  51   f  of the seat back  51 . 
     The seat back  51  includes a cushion portion  51   c  (see  FIG. 7 ) on the front surface thereof. The structure in the vehicle  1  in which the forward movement of the seat back  51  expands the capacity of the cargo bed  40 , prevents cargo in the cargo bed floor  43  from soiling the cushion portion  51   c  when the seat back  51  moves forward as shown in  FIG. 10 . 
     The seat frame  53  includes a locking mechanism  54  for fixing the position of the seat frame  53  in the usable state and in the unusable state. The position of the seat frame  53  in the usable state is hereinafter referred to as the “rear end position”. The position of the seat frame  53  in the unusable state is hereinafter referred to as the “front end position”. As shown in  FIG. 8 , in the example of the vehicle  1 , a front rod  45 A is located between the front portions of the right and left guide rails  44  and is fixed to the upper side of the cargo bed floor  43 . Also, a rear rod  45 B (see  FIG. 10 ) is located between the rear portions of the right and left guide rails  44  and is fixed on the upper side of the cargo bed floor  43 . The locking mechanism  54  includes a hook that is caught on the rods  45 A and  45 B to fix the position of the seat frame  53  and an operating member for the operator to release the engagement between the hook and the rods  45 A and  45 B. When the hook is caught on the rear rod  45 B, the seat frame  53  is fixed to the rear end position shown in  FIG. 6 . When the hook of the lock mechanism  54  is caught on the front rod  45 A, the seat frame  53  is fixed to the front end position shown in  FIG. 11 . When the engagements between the hook and the rods  45 A, and  45 B are released by operating the operating member of the lock mechanism  45 , the seat frame  53  is allowed to slide forward or rearward. In an example, the seat frame  53  is allowed to be fixed only at these two positions and is not allowed to be fixed at a middle position. The structure of the lock mechanism  54  may be changed as long as the seat frame  53  is allowed to be fixed to the rear end position and the front end position. 
     [Fixing Structure Between Cargo Bed Frame and Guide Rail] 
     As mentioned above, the guide rails  44  are fixed to the cargo bed frame  20 C. As shown in  FIG. 9 , the cargo bed frame  20 C includes the right and left floor support portions  24  and the floor cross portions  22 B and  22 D fixed to the right and left floor support portions  24 . The floor cross portion  22 D is spaced away from the floor cross portion  22 B. The guide rails  44  extends between the floor cross portions  22 B and  22 D. The front end and the rear end of the guide rails  44  are fixed to the floor cross portions  22 B and  22 D, respectively. 
     As described above, both ends of the floor cross portion  22 B are respectively connected to the extending portions  21  provided at the right end and the left end of the main body frame  20 . As shown in  FIG. 5A , in the example of the vehicle  1 , both ends of the floor cross portion  22 B are connected to the rear vertical portions  21 C of the main body frame  20 . Accordingly, the floor cross portion  22 B improves the strength for supporting the rear seat  50 . In the example of the vehicle  1 , both ends of the rear floor cross portion  22 D are not connected to the extending portion  21  of the main body frame  20 . Alternatively, both ends of the floor cross portion  22 D may be connected to, for example, side wall extending portions  21 D, each constituting a portion of the extending portion  21  via a bracket extending in the vertical direction. As shown in  FIG. 9 , the floor support portions  24  extend rearward beyond the floor cross portion  22 D and the rear ends of the guide rails  44 . This allows the cargo bed floor  43  to include the rear area A 2  located behind the rear ends of the guide rails  44 . The length in the front-rear direction of the area where the guide rails  44  are located is larger than the length in the front-rear direction of the rear area A 2 . 
       FIG. 12  is a cross-sectional view taken along a line XII-XII shown in  FIG. 7 .  FIG. 13  is a cross-sectional view taken along a line XIII-XIII shown in  FIG. 10 . As shown in  FIG. 13 , the floor panel  43 F has a plurality of concave portions  43   b  and a plurality of convex portions  43   c  each extending in the front-rear direction and aligned in the right-left direction (the concave portions  43   b  and the convex portions  43   c  are not shown in  FIG. 7  and  FIG. 10 ). As shown in  FIG. 12 , a plurality of ribs  43   d  are formed on the lower surface of the floor panel  43 F and aligned in the front-rear direction. The concave portions  43   b , the convex portions  43   c , and the ribs  43   d  improve the rigidity of the floor panel  43 F. In the example of the vehicle  1 , the ribs  43   d  are formed on the lower side of the convex portions  43   c.    
     The guide rails  44  fit into the concave portions  43   b  and the convex portions  43   c . When the rear seat  50  is in the unusable state and cargo is placed behind the rear seat  50 , this structure prevents the guide rails  44  from interfering with the cargo. In the example of the vehicle  1 , as shown in  FIG. 13 , the guide rail  44  is located inside a concave portion  43   b . The guide rail  44  includes a bottom portion  44   a , side walls  44   b , and a flange  44   c . The bottom portion  44   a  is fixed to the bottom of the concave portion  43   b . The guided portion  53   b  of the seat frame  53  is caught in the flange  44   c . The shape of the guide rail  44  is not limited to the example in the vehicle  1 . For example, the guide rail  44  may be formed so as to cover a convex portion  43   c.    
     As described above, the cargo bed floor  43  includes the rear area A 2  located behind the rear ends of the guide rails  44 . The concave portions  43   b , the convex portions  43   c , and the ribs  43   d  are formed in the rear area A 2 . That is, the concave portions  43   b  and the convex portions  43   c  extend rearward beyond the rear ends of the guide rails  44 . 
     [Seat Bottom] 
     As described above, the seat bottom  52  in the example of the vehicle  1  is allowed to move independently of the seat back  51 . In the example of the vehicle  1 , the seat bottom.  52  is arranged at the standing position when the rear seat  50  is in the unusable state (see  FIG. 8 ). More specifically, the seat bottom  52  is arranged such that its lower surface is substantially vertical. This structure enables the range of movement of the seat back  51  to easily increase in the front-rear direction. 
     The area A 4  shown in  FIG. 6  is an area where the seat bottom  52  is located when the rear seat  50  is in the usable state (this area A 4  is Hereinafter referred to as the “seat bottom area”). The seat bottom area A 4  is a range defined by the front edge  52   c  and the rear edge  52   b  of the seat bottom  52 . When the rear seat  50  is in the usable state, the lower end L of the seat back  51  is located further rearward than the seat bottom area A 4 . As shown in  FIG. 11 , when the rear seat  50  is in the unusable state, the seat bottom  52  recedes from the seat bottom area A 4  and then the lower end L of the seat back  51  is located in the seat bottom area A 4 . 
     In the example of the vehicle  1 , as shown in  FIG. 11 , when the rear seat  50  is in the unusable state, the lower end L of the seat back  51  moves to the front half area within the seat bottom area A 4 . The front half area of the seat bottom area A 4  means an area defined further forward than the center C 1  in the front-rear direction of the seat bottom area A 4 . That is, the lower end L of the seat back  51  moves forward beyond the center C 1  of the seat bottom area A 4  in the front-rear direction. As described here, a large movable range is secured for the seat back  51  in the example of the vehicle  1 . The movable range of the seat back  51  is not limited to the example of the vehicle  1 . That is, the lower end L of the seat back  51  may be located rearward of the center C 1  when the rear seat  50  is in the unusable state. 
     As shown in  FIG. 10 , in the example of the vehicle  1 , the rear ends of the guide rails  44  are located further rearward than the center C 2  in the front-rear direction of the cargo bed floor  43 . When the rear seat  50  is in the usable state, the lower end L of the seat back  51  is located in an area defined behind the center C 2  of the cargo bed floor  43 . The front ends of the guide rails  44  are located further forward than the center C 2  of the cargo bed floor  43 . Therefore, when the rear seat  50  is in the unusable state, the lower end L of the seat back  51  is located in the area ahead of the center C 2  of the cargo bed floor  43 . Unlike the vehicle  1 , if the length of the cargo bed floor  43  in the front-rear direction is sufficiently large, the lower end L of the seat back  51  may be located further forward than the center C 2  of the cargo bed floor  43  even when the rear seat  50  is in the usable state. 
     In the example of the vehicle  1 , as shown in  FIG. 11 , when the rear seat  50  is in the unusable state, the seat bottom  52  and the seat back  51  partially overlap in a side view of the vehicle body. Specifically, the bottom surface of the seat bottom  52  is positioned between the edges  51   e  in the right-left direction of the seat back  51 , and at least the front ends of the edges  51   e  overlap with the seat bottom  52  (in this description, the “bottom surface” of the seat bottom  52  means a surface that faces downward when the rear seat  50  is in the usable state). Unlike the example of the vehicle  1 , the edges  51   e  of the seat back  51  may be located behind the seat bottom  52  when the rear seat  50  is in the unusable state. 
     In the example of the vehicle  1 , when the rear seat  50  is in the unusable state, the seat bottom  52  is arranged at the standing position and the seat surface  52   a  of the seat bottom  52  faces forward. This orientation of the seat back  51  prevents cargo placed on the cargo bed floor  43  from soiling the seat surface  52   a  when the rear seat  50  is in the unusable state. Also, when the rear seat  50  is in the unusable state, the seat back  51  supported by the seat frame  53  is located behind the seat bottom  52 . As a result, the seat back  51  prevents a large force from being applied to the seat bottom  52  from cargo placed on the cargo bed floor  43 . More specifically, the seat back  51  prevents a large force from being applied to the support mechanism (a pivot shaft  46   a  and brackets  46 A,  46 B connected to the pivot shaft  46   a ) of the seat bottom  52 . 
     As shown in  FIG. 11 , when the rear seat  50  is in the unusable state, at least a part of the seat bottom  52  is located further forward than the cargo bed floor  43 . More specifically, at least a part of the seat bottom  52  is located further forward than the front edge  43   a  of the cargo bed floor  43 . As a result, when the rear seat  50  is in the unusable state, the arrangement of the seat bottom  52  effectively utilizes the space secured between the cargo bed  40  and the front seat  4  (this space is for the rider to put his legs). This structure enables the seat back  51  to have a large movable range thereof. As shown in  FIG. 10 , in the example of the vehicle  1 , when the rear seat  50  is in the unusable state, the side surface  52   d  of the seat bottom  52  is located further forward than the front edge  43   a  of the cargo bed floor  43 . 
     As shown in  FIG. 11 , in the example of the vehicle  1 , when the rear seat  50  is in the unusable state, the side surface  52   d  of the seat bottom  52  is located further forward than the bent portion between the rear vertical portion  21 C and the side wall extending portion  21 D of the main body frame  20 . More specifically, when the rear seat  50  is in the unusable state, the entire seat bottom  52  is located further forward than the bent portion between the rear vertical portion  21 C and the side wall extending portion  21 D. 
     As described above, the seat bottom  52  is allowed to move to the standing position at which the seat bottom  52  is arranged in the unusable state of the rear seat  50  and to a laid position (a position shown in  FIG. 6 ) at which the seat bottom  52  is arranged in the usable state of the rear seat  50 . In the example of the vehicle  1 , the lower surface of the seat bottom  52  is supported by the guide rails  44  when the seat bottom  52  is in the laid position. That is, the lower surface of the seat bottom  52  is in contact with the upper surface of the guide rails  44 . This structure does not employ a dedicated member for supporting the seat bottom  52 . Therefore, this structure avoids an increase in the number of components (parts) while increasing the support strength of the seat bottom  52 . 
     As shown in  FIG. 8 , in the example of the vehicle  1 , the seat bottom  52  is supported by a hinge mechanism and thus is movable to the standing position and the laid position around the pivot shaft  46   a  of the hinge mechanism. The pivot shaft  46   a  is supported at the foremost position of the cargo bed frame  20 C. When the seat bottom  52  is in the standing position, the structure described above enables a large area to be secured behind the seat bottom  52 , that is, to be secured for the seat back  51 . 
     As described above, the cargo bed frame  20 C in the example of the vehicle  1  includes a floor cross portion  22 B (see  FIG. 9 ) located at the foremost position of the cargo bed frame  20 C. As shown in  FIG. 6 , the pivot shaft  46   a  is attached to the floor cross portion  22 B via a bracket  46 A. The bracket  46 A is attached to the front surface of the floor cross portion  22 B. This arrangement of the bracket  46 A enables the seat bottom  52  in the standing position to be located closer to the front seat  4 . 
     As shown in  FIG. 8 , the seat bottom  52  is connected to the pivot shaft  46   a  via a bracket  46 B. The bracket  46 B is attached to, for example, the bottom surface of the seat bottom  52 . When the rear seat  50  is in the usable state, the pivot shaft  46   a  is located further forward than the front edge  52   c  of the seat bottom  52  (see  FIG. 6 ). This arrangement enables the seat bottom  52  in the standing position to be located closer to the front seat  4 . The position and the support structure of the pivot shaft  46   a  is not limited to the example of the vehicle  1  and may be changed. 
     The movement of the seat bottom  52  and the orientation and the position of the seat back  51  in the unusable state are not limited to the example of the vehicle  1 . For example, the seat bottom  52  and the seat back  51  may be configured to move integrally in the front-rear direction. In this case, when the rear seat  50  is in the unusable state, the seat bottom  52  may be placed in the laid position and most of the seat bottom  52  may be located further forward than the front edge  43   a  of the cargo bed floor  43 . As a result, the seat back  51  may be located in the front half area of the seat bottom area A 4 . 
     In yet another example, when the rear seat  50  is in the unusable state, the seat bottom  52  may be configured to stand along the side wall  41  of the cargo bed  40  and the seat bottom  52  may be located in the front half area of the seat bottom area A 4 . 
     In yet another example, a hinge mechanism that allows movement of the seat bottom  52  may be arranged in the rear portion of the seat bottom  52 . In addition, the seat bottom  52  may be connected to the seat back  51  via the hinge mechanism. In this structure, the seat bottom  52  rotates so that the rear end of the seat bottom  52  goes under the seat bottom  52 , and the rotation moves the seat bottom  52  to the standing position. In this case, the seat back  51  and the seat bottom  52  may be integrally moved in the front-rear direction. 
     As described above, the roll cage  30  includes a cross portion  32 D (see  FIG. 5B ) extending between the right and left rear vertically extending portions  31 C. As shown in  FIG. 2 , when the rear seats  50  are in the usable state, the cross portion  32  D is located behind the seat backs  51  to support the seat backs  51 . In the example of the vehicle  1 , when the rear seats  50  are in the usable state, the lateral portions  32   b  of the cross portion  32 D are located behind the head rests  51   b , each of which is the upper portion of the seat back  51 , and support the head rests  51   b . When the rear seat  50  is in the usable state and no force is applied to the seat back  51  in the rearward direction, a clearance may be made between the lateral portion  32   b  of the cross portion  32 D and the head rest  51   b , or alternatively the lateral portion  32   b  may be in contact with the head rest  51   b.    
     [Seat Belt Mechanism] 
     The rear seat  50  is provided with a seat belt mechanism. As shown in  FIG. 3 , the seat belt mechanism includes a retractor  56   b  for accommodating a part of the belt to adjust the length of the belt. In the example of the vehicle  1 , the retractor  56   b  is located below the cross portion  32 D and is attached to the rear vertically extending portion  31 C of the roll cage  30  (see  FIG. 5B ). The seat belt mechanism also includes a guide anchor  56   a  for guiding the belt extending out of the retractor  56   b . In the example of the vehicle  1 , the guide anchor  56   a  is attached to the cross portion  32 D. Specifically, the guide anchor  56   a  is attached to the end of the cross portion  32 D. The belt extends from the retractor  56   b  toward the guide anchor  56   a  and then extends downward from the guide anchor  56   a . Employing the cross portion  32 D as a member for supporting the guide anchor  56   a  contributes to a reduction in the number of components (parts). 
     As shown in  FIG. 7 , the cargo bed floor  43  is provided with buckles  56   d . When using the seat belt mechanism, a joint (tongue plate) provided to the belt extending from the guide anchor  56   a  is connected to the buckle  56   d . The Buckles  56   d  are located between the right and left rear seats  50 . As shown in  FIG. 5A , the end of the buckle  56   d  is fixed to the cargo bed frame  20 C, for example. In the example of the vehicle  1 , the end of the buckle  56   d  is fixed to the floor cross portion  22 E bridged over the floor support portions  24 . 
     The cargo bed floor  43  has an accommodating portion formed thereon for accommodating the buckles  56   d . Specifically, as shown in  FIG. 12 , a recess  43   e  is formed in the floor panel  43 F constituting the cargo bed floor  43  and functions as the accommodating portion for accommodating the buckles  56   d . A lid  43   f  for closing the recess  43   e  is attached to the cargo bed floor  43 . The upper surface of the lid  43   f  is located at the same height as the floor panel  43 F in a state in which the lid  43   f  closes the recess  43   e.    
     The present invention is not limited to the above-described embodiments. It is obvious to those skilled in the art that there are other embodiments that can obtain similar functions and results. The claims cover the substantially equivalent other embodiments.