Patent Document

BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a body structure of a fuel cell vehicle. More specifically, the present invention relates to a body structure of a fuel cell vehicle, which is capable of protecting a fuel feed pipe that connects a fuel cell to a fuel tank which stores fuel for the fuel cell. 
   2. Description of Related Art 
   A fuel cell vehicle in which hydrogen, as a fuel gas, and oxygen, as an oxidizing agent, are supplied to generate power, and which uses the power to drive a motor, is known as a type of automobile. 
   In such a fuel cell vehicle, hydrogen which acts as a fuel gas is filled in a fuel tank and is supplied to a fuel cell together with oxygen which is extracted from the air. Accordingly, it is necessary to connect the fuel tank for storing the hydrogen gas to the fuel cell by using a fuel feed pipe. 
   Although sufficient safety against collisions is provided for the above-mentioned fuel cell and the fuel tank, it is also necessary to provide the same degree of safety for the fuel feed pipe which connects the fuel cell and the fuel tank. However, in order to ensure such safety for the fuel feed pipe, an increase in the weight of a vehicle is inevitable since it becomes necessary to provide a protector for the fuel feed pipe or increase the strength and rigidity of a panel surrounding the protector. 
   Also, as disclosed in Japanese Unexamined Patent Application, First Publication No. 2000-149974, a structure has been proposed in which a fuel cell is disposed at a roof portion in order to increase safety for collisions from any direction. However, there is a disadvantage in this structure in that the weight balance of the vehicle tends to be disturbed since it becomes necessary to increase the rigidity of the roof. 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the invention is to provide a body structure for a fuel cell vehicle which is capable of securely protecting a fuel feed pipe while preventing an increase in the body weight of a vehicle. 
   In order to achieve the above object, the present invention provides a body structure of a fuel cell vehicle which is driven using power generated by a fuel cell (for instance, a fuel cell  38  in an embodiment described later), comprising: a frame unit (for instance, a sub-frame  22  in an embodiment described later), which supports a fuel tank (for instance, hydrogen tanks  29  and  30  in an embodiment described later) for storing fuel for the fuel cell; a fuel cell box (for instance, a fuel cell box  39  in an embodiment described later) which accommodates the fuel cell, the fuel cell box being disposed in proximity of the frame unit at a floor (for instance, a front floor  1 , or a rear floor  2  in an embodiment described later) of the vehicle; a fuel feed pipe (for instance, an assembly pipe  46 , or feed pipes  47  and  49  in an embodiment described later) which connects the fuel tank and the fuel cell; and a pillar (for instance, a center pillar  71  or  81  in an embodiment described later) which is disposed at a position, viewed from the side of the vehicle, covering at least a part of the fuel cell box and at least a part of the frame unit. 
   According to the body structure described above, even if an obstacle is advanced between the fuel cell box and the frame unit from the side direction, it becomes possible to prevent the advance of the obstacle by the act of the pillar which is a framework for the side of the vehicle. Accordingly, a portion between the fuel cell box and the frame unit of the fuel feed pipe connecting the fuel tank and the fuel cell unit may be protected without using any special members. 
   The present invention also provides a body structure of a fuel cell vehicle which is driven using power generated by a fuel cell, comprising: a frame unit which supports a fuel tank for storing fuel for the fuel cell; a fuel cell box which accommodates the fuel cell, the fuel cell box being disposed in proximity of the frame unit at a floor of the vehicle; a fuel feed pipe which connects the fuel tank and the fuel cell; and a junction portion (for instance, a junction portion S in an embodiment described later) formed by a pillar and a side sill (for instance, a side sill  70  or  80  in an embodiment described later), which is disposed at a position, viewed from the side of the vehicle, covering at least a part of the fuel cell box and at least a part of the frame unit. 
   According to the body structure described above, even if an obstacle is advanced between the fuel cell box and the frame unit from the side direction, it becomes possible to prevent the advance of the obstacle by the act of the junction portion formed by the pillar and the side sill which is a framework for the side of the vehicle having relatively high rigidity. Accordingly, a portion between the fuel cell box and the frame unit of the fuel feed pipe connecting the fuel tank and the fuel cell unit may be securely protected without using any special members. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Some of the features and advantages of the invention have been described, and others will become apparent from the detailed description which follows and from the accompanying drawings, in which: 
       FIG. 1  is a diagram showing a plan view of a body structure according to an embodiment of the present invention; 
       FIG. 2  is a diagram showing a side view of the body structure shown in  FIG. 1  according to the embodiment of the present invention; 
       FIG. 3  is a diagram showing a cross-sectional view taken along the line A—A shown in  FIG. 1 ; and 
       FIG. 4  is a diagram showing a perspective view of a front bracket which may be used in an embodiment according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention summarized above and defined by the enumerated claims may be better understood by referring to the following detailed description, which should be read with reference to the accompanying drawings. This detailed description of particular preferred embodiments, set out below to enable one to build and use particular implementations of the invention, is not intended to limit the enumerated claims, but to serve as particular examples thereof. 
   Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 
   As shown in  FIGS. 1 through 3 , a rear floor  2  having a step portion  3  which is formed so as to be uplifted at the back is joined to a rear end of a front floor  1 . A cross member  4  (shown in  FIG. 1  only) which forms a part of the framework of a vehicle is welded at the bottom of the step portion  3  of the rear floor  2  over the width direction of the vehicle. A pair of floor frames  5  and  6  that also form a part of the framework of the vehicle are connected to the bottom surface of the front floor  1  at left hand side and right hand side thereof, respectively, along the longitudinal direction of the vehicle. 
   A pair of inside sills  7  and  8  are connected to the right and left hand side edge portions, respectively, of the front floor  1 , and inside sill extensions  9  and  10  are attached to the rear edge portion of the inside sills  7  and  8 , respectively. Also, outside sills  7 ′ and  8 ′ are welded to the inside sills  7  and  8 , respectively, to form each of side sills  70  and  80  that form the framework of the vehicle. 
   As shown in  FIG. 4 , front brackets  11  and  12  are attached to an inside surface of the inside sills extensions  9  and  10 , respectively. Note that in  FIG. 4 , only the inside sill extension  9  and the front bracket  11  located at the left hand side are shown, and the inside sill extension  10  and the bracket  12  are indicated by corresponding numerals shown in the brackets. 
   A flange portion  11   f  ( 12   f ) of rear upper end of the front bracket  11  ( 12 ) is attached to a bottom wall of a rear frame  13  ( 14 ), which will be explained later, and a flange portion  11   g  ( 12   g ) of front upper end of the front bracket  11  ( 12 ) is attached to a lower surface of the cross member  4 . Also, a front wall  11   b  ( 12   b ) extends in a front direction together with an inner wall  11   a  ( 12   a ) to become a front frame connection portion  11   h  ( 12   h ) and attached to the floor frame  5  ( 6 ). Moreover, a collar nut  15  ( 16 ) is provided with the bottom wall of the front bracket  11  ( 12 ). Here, the rear frame  13  ( 14 ) is a member which is attached to the lower surface of the rear floor  2  and forms the framework of the vehicle. 
   Accordingly, a front end portion of the rear frame  13  ( 14 ) is connected to the side sill  70  ( 80 ) and the floor frame  5  ( 6 ) via the front bracket  11  ( 12 ). 
   As shown in  FIG. 2 , rear brackets  17  and  18  having a cross-section opened upwardly, are attached to the lower surface of the rear edge portion of the rear frames  13  and  14 , respectively. Side walls of each of the rear brackets  17  and  18  are attached to the outside of both side walls of the rear frames  13  and  14 , and collar nuts  19  and  20  are provided with the bottom wall of the front portion. 
   In this embodiment, as shown in  FIG. 1 , two cross members  4 A and  4 B are provided so as to connect the left and right hand side rear frames  13  and  14 , and a bumper beam  21  is attached to a rear edge portion thereof, i.e., to a rear edge of the rear brackets  17  and  18 . 
   Also, a sub-frame (frame unit)  22  is fixed to the front brackets  11  and  12  and the rear brackets  17  and  18  by screwing a bolt  23  into each of the collar nuts  15 ,  16 ,  19 , and  20  from the bottom. 
   The sub-frame  22  includes a cross-beam  28  which is a member formed in a rectangular shape by right and left frame members  24  and  25  and front and back frame members  26  and  27  and extends in the width direction of the vehicle, and two hydrogen tanks  29  and  30  which function as fuel tanks are disposed at a respective position separated by the cross-beam  28  being tightened and fixed by bands  31  and  32 , respectively. Also, a suspension unit  33  is attached to the sub-frame  22 , and a tire, which is not shown in the figure, is attached to the suspension unit  33 . 
   In addition, insertions  34  and  35  for the bolts  23  which are inserted into the above collar nuts  15  and  16  are provided at corners formed by the front edge of the left and right frame members  24  and  25  and both ends of the front frame member  26 . Likewise, insertions  36  and  37  for the bolts  23  which are inserted into the above collar nuts  19  and  20  are provided at comers formed by the rear edge of the left and right frame members  24  and  25  and both ends of the rear frame member  27 . 
   Accordingly, the sub-frame  22  is fixed to the rear frames  13  and  14  by inserting the bolt  23  into each of the insertions  34 ,  35 ,  36 , and  37  of the sub-frame  22  formed in the manner as mentioned above, and screwing the bolt  23  into the collar nuts  15 ,  16 ,  19 , and  20 , which are provided with the front brackets  11  and  12  and the rear brackets  17  and  18  of the rear frames  13  and  14 . In this embodiment, the front frame member  26  of the above-mentioned sub-frame  22  includes a flat surface  26   a  at the front thereof. 
   As shown in  FIGS. 1 and 3 , a fuel cell box  39  in which a fuel cell unit FCU including a fuel cell  38  and accessories is accommodated, is disposed below the front floor  1  so as to extend over the above-mentioned left and right floor frames  5  and  6 . 
   The fuel cell  38  drives the fuel cell vehicle by reacting hydrogen gas supplied from the above-mentioned hydrogen tanks  29  and  30  with oxygen contained in air supplied from a compressor, which is not shown in the figure, to generate power, and by supplying the generated power to a driving motor. 
   The fuel cell box  39  includes a case main body  39   a  which covers the fuel cell unit FCU, and a cover  39   a  provided so as to cover the case main body  39   a . The case main body  39   a  has a convex shape viewed from the side thereof, and hence the cover  39   b  is made to have a shape which matches the convex shape of the case main body  39   a . The case main body  39   a  and the cover  39   b  are fixed to the bottom walls  5   a  and  6   a  of the floor frames  5  and  6 , respectively, by tightening bolts  40  using nuts  41  as shown in FIG.  3 . Note that a flat surface  39   c  (shown in  FIGS. 1 and 2 ) is formed at the rear surface of the fuel cell box  39 , i.e., the rear surface of the case main body  39   a . The flat surface  39   c  at the back of the fuel cell box  39  is disposed in proximity to the flat surface  26   a  of the front of the sub-frame  22  (the front frame member  26 ) so as to oppose the other. 
   Here, as shown in  FIGS. 1 and 2 , the hydrogen tanks  29  and  30  are connected by high pressure assembly pipes  46 , and a feed pipe  47  which is connected to the assembly pipes  46  and extends along the inside of the frame member  25  of the sub-frame  22  to reach the front portion of the hydrogen tank  29 , is connected to a regulator  48  disposed between the hydrogen tanks  29  and  30 . A feed pipe  49  which extends in a front direction from the regulator  48  and is arranged so as to extend and cross over the sub-frame  22  and the fuel cell box  39  within the width thereof, is inserted into the fuel cell unit FCU disposed in the fuel cell box  39  through the left rear portion at the back of the box  39 . 
   Also, a portion M of the feed pipe  49  which extends from the regulator  48  towards the front direction is located at a position connecting the fuel cell box  39  to the sub-frame  22 , and at the side of the portion M, each of the center pillars  71  and  81  is disposed at a position viewed from the side of the vehicle, extending from the back of the fuel cell box  39  over the front of the sub-frame  22 . 
   More specifically, as shown in  FIG. 3  which shows the left side of the body structure of the vehicle (note that the right hand side thereof is indicated only by numerical numbers in parentheses), the inside sill  7  ( 8 ) and the outside sill  7 ′ ( 8 ′) are welded to the flange portion  78   f  and  78   f ′ at the upper and the lower ends thereof to form the side sill  70  ( 80 ) as a structure having a closed cross-section. The inside pillar  71   a  ( 81   a ) is welded to the upper flange portion  78   f  and the outside pillar  71   b  ( 81   b ) is welded to the outside surface of the outside sill  7 ′ ( 8 ′), and the inside pillar  71   a  ( 81   a ) and the outside pillar  71   b  ( 81   b ) form the center pillar  71  ( 81 ) as the framework of the vehicle. 
   Also, as mentioned above, the portion M of the feed pipe  49  which extends from the regulator  48  towards the front direction is located at the position between the fuel cell box  39  and the sub-frame  22 , and at the side of the portion M, a junction portion S of the side sill  70  ( 80 ) and the center pillar  71  ( 81 ) having relatively high rigidity as the framework for the side of the vehicle is disposed, viewed from the top, so as to cover the back of the fuel cell box  39  and the front of the sub-frame  22 . 
   In this embodiment, three brackets  42  at one side, hence six at both sides, are welded to portions between the left and right floor frames  5  and  6  and the inside sills  7  and  8 . The bracket  42  includes a flange portion  42   a  which is connected to the back of the floor frames  5  and  6 , the inside sills  7  and  8 , and the front floor  1 . 
   According to the above embodiment, if a load is applied to the bumper beam  21  of the left and right rear frames  13  and  14 , for example, when the vehicle is hit from the back, the load is divided and transmitted to each of the inside sills  7  and  8  and the floor frames  5  and  6  via the front brackets  11  and  12 . Accordingly, no large load is applied to the sub-frame  22 , and hence it becomes possible to securely protect the hydrogen tanks  29  and  30 . 
   Also, the front end portion of the sub-frame  22  is connected to the front brackets  11  and  12  via the collar nuts  15  and  16 , and the inside sills  7  and  8  and the floor frames  5  and  6  are connected to the outside and inside, respectively, of the interior of the vehicle. Accordingly, when a load generated by a collision is applied to the rear end portion of the sub-frame  22  (in a front direction indicated by an arrow in FIG.  1 ), for example, the load is divided into two parts by the front brackets  11  and  12 , and is applied to the inside sills  7  and  8  and the floor frames  5  and  6 . 
   Accordingly, as compared with the case where the collision load is concentratedly applied to the inside sills  7  and  8  or the floor frames  5  and  6 , it becomes possible to increase the supporting strength and supporting rigidity by a degree corresponding to the divided load. Also, since the collision load is applied in a direction compressing the inside sills  7  and  8  and the floor frames  5  and  6  at that time, this is advantageous from the viewpoint of increasing its strength. 
   As a result, it becomes possible to securely protect the hydrogen tanks  29  and  30  of the sub-frame  22 . 
   Moreover, if the position of the sub-frame  22  is changed towards the front direction when the collision load is applied to the front of the sub-frame  22 , it is possible to reliably prevent the breakage of the fuel cell box  39  as compared with the case where the load is concentratedly applied to a part of the rear surface of the fuel cell box  39  since the flat surface  26   a  at the front of the frame member  26  of the sub-frame  22  is disposed so as to oppose the flat surface  39   c  at the back of the fuel cell box  39  so that the flat surface  26   a  of the sub-frame  22  makes the pressing force act uniformly over the entire flat surface  39   c  of the fuel cell box  39  and that the load is applied in a dispersed manner over the entire surface. 
   Furthermore, when the vehicle is hit from the side direction and an obstacle is about to enter between the fuel cell box  39  and the sub-frame  22 , the center pillars  71  and  81  which extends in the up-and-down direction of the vehicle function as protectors and prevents the obstacle from moving into the vehicle. Accordingly, among the feed pipes connecting the fuel cell unit FCU and the hydrogen tanks  29  and  30 , it becomes possible to prevent the portion M which is a part of the feed pipe  49  at the downstream of the regulator  48  and is located at the position connecting the fuel cell box  39  and the sub-frame  22 , from being damaged by the obstacle. 
   In particular, since the junction portion S of the side sills  70  and  80  and the center pillars  71  and  81  having a relatively high rigidity as the framework at the sides of the vehicle, is disposed at the side of the portion M located between the fuel cell box  39  and the sub-frame  22 , when the load is applied to the junction portion S, the load is divided and supported by the floor frames  5  and  6  via the bracket  42  and by a roof side frame, which is not shown in the figure, via the center pillars  71  and  81 . 
   Accordingly, since the invasion of the obstacle is prevented and the junction portion S of the side sills  70  and  80  and the center pillars  71  and  81  is not deformed by the invading obstacle, it becomes possible to reliably prevent the breakage of the portion M which is located between the fuel cell box  39  and the sub-frame  22 . Note that since tires which are attached to the suspension unit  22  are provided at the side of the sub-frame  22 , it becomes possible to oppose a collision from this side direction and the safety against collision may also be secured for this portion. 
   As a result, it become unnecessary to provide a protector which covers the side of the feed pipe  49  for specially protecting the portion M between the fuel cell box  39  and the sub-frame  22  or to increase the strength and the rigidity of a panel therearound. Accordingly, it becomes possible to reliably protect the feed pipe  49 , without increasing the body weight, by effectively using the available framework of the vehicle. 
   Note that since the assembly pipes  46 , the feed pipe  47 , and the rear portion of the feed pipe  49  are surrounded and protected by the frame members  24 ,  25 ,  26 , and  27  of the sub-frame  22 , and the front portion of the feed pipe  49  is placed so as to be within the width size of the fuel cell box  39 , it becomes possible to securely protect the pipes from an obstacle coming from the sides of the vehicle. 
   Also, note that the present invention is not limited, by any means, to the embodiments explained above, and it is possible to apply the present invention as long as the portion M between the fuel cell  39  and the sub-frame  22  is present for a feed pipe connecting the hydrogen tanks  29  and  30  and the fuel cell unit FCU. 
   Having thus described exemplary embodiments of the invention, it will be apparent that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements, though not expressly described above, are nonetheless intended and implied to be within the spirit and scope of the invention. Accordingly, the foregoing discussion is intended to be illustrative only; the invention is limited and defined only by the following claims and equivalents thereto.

Technology Category: 7