Abstract:
A fuel cell system includes a fuel cell for causing electrochemical reactions of anode gas and cathode gas, a fuel cell system case accommodating the fuel cell, and a frame disposed below the fuel cell system case and fixing the fuel cell system case. A rib is provided on an upper surface of the frame. A water reservoir portion is provided in the bottom of the fuel cell system case so that the water reservoir portion is a concave in an inner side of the fuel cell system case and is a convex in the outside of the fuel cell system case. The water reservoir portion is located at a position at which at least a part of the convex vertically overlaps with the rib.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Japanese Patent Application No, 2014-232034, filed on Nov. 14, 2014, the contents of all of which are incorporated herein by reference in their entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to a fuel cell system. 
         [0004]    2. Related Art 
         [0005]    Water is produced by electrochemical reactions when a fuel cell generates power. JP2009-289426A etc. discloses an art in which, since such water may leak from the fuel cell, a recessed portion (water reservoir portion) for accommodating the produced water is formed in a part of an inner bottom of a case where the fuel cell is accommodated. 
         [0006]    However, when the recessed portion is formed in the part of the inner bottom of the case for accommodating the fuel cell, the fuel cell system including the case entirely increases in a vertical size. 
       SUMMARY 
       [0007]    The present invention is made in order to address at least a part of the subject described above, and can he implemented in terms of the following aspects. 
         [0008]    (1) According to one aspect of the invention, a fuel cell system is provided, which includes a fuel cell for causing electrochemical reactions of anode gas and cathode gas, a fuel cell system case accommodating the fuel cell, and a frame disposed below the fuel cell system case and fixing the fuel cell system case. A rib is provided on an upper surface of the frame. A water reservoir portion is provided in the bottom of the fuel cell system. case so that the water reservoir portion is a concave in an inner side of the fuel cell system case and is a convex in the outside of the fuel cell system case. The water reservoir portion is located at a position at which at least a part of the convex vertically overlaps with the rib. According to this aspect, water can be reserved in the water reservoir portion, without increasing the height of the fuel cell system. 
         [0009]    (2) The fuel cell system of the aspect described above may further include a plurality of auxiliary machineries used for operation of the fuel cell. The fuel cell system case may include an auxiliary machinery case where the plurality of auxiliary machineries are accommodated. The water reservoir portion may be provided in the bottom of the auxiliary machinery case. According to this aspect, the water reservoir portion can be formed in the auxiliary machinery case, without increasing the height of the fuel cell system. 
         [0010]    (3) In the fuel cell system of the aspect described above, the water reservoir portion may include a plurality of water reservoir portions. According to this aspect, water which exists inside the fuel cell system case can be dividedly reserved in the plurality of water reservoir portions. 
         [0011]    The present invention can be implemented in various forms, such as a method of manufacturing the fuel cell system, a computer program for implementing the manufacturing method, and a recording medium that records the computer program. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  is a view schematically illustrating a fuel cell system used for one embodiment of the present invention; 
           [0013]      FIG. 2  is a schematic view illustrating an inside of an auxiliary machinery case; 
           [0014]      FIG. 3  is a view schematically illustrating the auxiliary machinery case of the fuel cell system, seen from above; and 
           [0015]      FIG. 4  is a cross-sectional view illustrating the auxiliary machinery case of the fuel cell system taken along a line A-A of  FIG. 3 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     A. Embodiment 
       [0016]      FIG. 1  is a view schematically illustrating a fuel cell system  10  used for one embodiment of the invention. In  FIG. 1 , a positive X-axis direction indicates front or forward of a vehicle, a positive Y-axis direction indicates up or upward of the vehicle, and a positive Z-axis direction indicates right or rightward of the vehicle. The fuel cell system  10  includes a fuel cell system case  140  and a frame  200 . The fuel cell system  10  is mounted on the vehicle. In this embodiment, the fuel cell system  10  is provided below a vehicle cabin. 
         [0017]    The fuel cell system case  140  includes a fuel cell case  100  and an auxiliary machinery case  130 . A gasket seals between members of the fuel cell system case  140  so that foreign matters, such as water and dust, do not enter thereinto. 
         [0018]    The fuel cell case  100  accommodates a fuel cell which causes electrochemical reactions of hydrogen gas as anode gas and oxygen gas as cathode gas. The fuel cell is comprised of unit cells which are stacked, and is oriented so that stacking directions is parallel to vehicle width directions. 
         [0019]    The fuel cell case  100  includes manifolds  120  for covering a side face of the fuel cell on the right side of the vehicle (positive side in Z-axis directions), a stack case for covering other side faces and an upper surface, and a lower cover not illustrated) for covering a lower surface of the fuel cell. The manifolds  120  form flow paths of hydrogen gas, oxygen gas, and cooling water for cooling the fuel cell. Further, the manifolds  120  have functions to secure insulation from high-voltage components inside the fuel cell case  100 , and to compress the unit cells. 
         [0020]      FIG. 2  is a schematic view illustrating an inside of the auxiliary machinery case  130 . X-Y-Z coordinate system in  FIG. 2  corresponds to X-Y-Z coordinate system in  FIG. 1 . The same can also be said in other drawings. 
         [0021]    The auxiliary machinery case  130  accommodates a plurality of auxiliary machineries (not illustrated) used for operation of the fuel cell. Here, the plurality of auxiliary machineries include, a hydrogen pump, injectors, exhaust and drain valves, valves, sensors, etc., for example. Pipings for cooling water, wirings for supplying power to the auxiliary machineries, etc. are provided to the auxiliary machinery case  130 , in addition to the auxiliary machineries. 
         [0022]    A plurality of openings  132  ( 132 A to  132 E) are formed in the auxiliary machinery case  130 . The opening  132  is used as a wiring hole through which the wirings pass, a piping hole through which the pipings of gas and cooling water used for the fuel cell pass, and a service hole for a connecting work of the wirings, etc. The auxiliary machinery case  130  is provided with water reservoir portions  131 A,  131 B, and  131 C, which will be described in detail later. In this embodiment, a plurality of auxiliary machineries are fixed to the manifolds  120 . Further, a side face of the auxiliary machinery case  130  on the left side of the vehicle (negative side in Z-directions) is covered with the manifolds  120 . 
         [0023]    In order to prevent vibration and noise caused by the auxiliary machineries from transmitting to the outside, the surface of the auxiliary machinery case  130  is covered with covers  141  and  142  made of natural or synthetic resin (see  FIG. 1 ). In this embodiment, the resin covers  141  and  142  have an inner layer made of urethane and an outer layer made of hard resin. 
         [0024]    The frame  200  is provided below the fuel cell system case  140 , and supports the fuel cell system case  140  by a vibration-proof mount structure. That is, in order to reduce the vibration, a rubber vibration insulator is disposed between the fuel cell system case  140  and the frame  200 . The frame  200  fixes the fuel cell system case  140  by inserting bolts  112 A and  112 B into bosses  111 A and  111 B formed in the fuel cell case  100  of the fuel cell system case  140 , respectively. Note that other bosses and bolts (not illustrated) also exist on the front side of the vehicle (positive X-axis direction). The frame  200  is fastened to a vehicle body (not illustrated). 
         [0025]      FIG. 3  is a view schematically illustrating the auxiliary machinery case  130  of the fuel cell system  10 , seen from above the vehicle (seen from positive Y-axis direction). 
         [0026]      FIG. 4  is a cross-sectional view illustrating the auxiliary machinery case  130  of the fuel cell system  10  taken along a line A-A of  FIG. 3 . Note that illustration of the auxiliary machineries is omitted in these drawings. The frame  200  is formed by welding a lower member  210  to an upper member  220 . Ribs  221 A and  221 B are formed on an upper surface of the frame  200 . In this embodiment, the ribs  221 A and  221 B extend in vehicle width directions (Z-axis directions). The rigidity of the frame  200  can be secured by the ribs  221 . 
         [0027]    The water reservoir portions  131  ( 131 A to  131 B) are formed inside the bottom of the auxiliary machinery case  130 , which are recessed downwardly or in negative Y-axis direction, relatively to the other bottom portions. Specifically, each water reservoir portion is a concave when seen from inside the auxiliary machinery case  130 , and a convex when seen from outside. The downwardly convex portions of the water reservoir portions  131 A,  131 B, and  131 C are at least partially overlapped with the ribs  221 A and  221 B of the frame  200  in vertical directions (Y-axis directions). Further, the downwardly convex portions of the water reservoir portions  131 A,  131 B, and  131 C are not overlapped with the ribs  221 A and  221 B of the frame  200  in horizontal directions (X-axis directions). Note that since the auxiliary machinery case  130  is fixed to the manifolds  120  with bolts, a space exists between the auxiliary machinery case  130  and the frame  200  as illustrated in  FIG. 4 . 
         [0028]    Conventionally, when water reservoir portion(s) are formed in a fuel cell case, a fuel cell system entirely increases in a vertical size. On the other hand, in this embodiment, the water reservoir portions  131  are formed so that at least parts of the downwardly convex portions of the water reservoir portions  131  overlap with the ribs  221  in the vertical directions (Y-axis directions). Therefore, water can be reserved in the water reservoir portions  131 , without increasing the height of the fuel cell system  10 . Further, the water reservoir portions  131  are formed so that peaks of the downwardly convex portions of the water reservoir portions  131  do not overlap with the ribs  221  in the horizontal directions (X-axis directions). 
         [0029]    Water may possibly enter into the auxiliary machinery case  130  from outside. However, in this embodiment, since the water reservoir portions  131  are formed in the bottom of the auxiliary machinery case  130 , water is prevented from contacting the auxiliary machineries accommodated in the auxiliary machinery case  130 . 
       B. Modifications 
     B1. Modification 1 
       [0030]    In this embodiment, the water reservoir portions  131  are formed in the auxiliary machinery case  130 . However, the present invention is not limited to this structure. The water reservoir portions  131  may be provided to the fuel cell case  100 , or may be provided to both of the fuel cell case  100  and the auxiliary machinery case  130 . 
       B2. Modification 2 
       [0031]    The auxiliary machinery case  130  is provided with the plurality of water reservoir portions  131  in this embodiment. By having the structure, water which exists inside the auxiliary machinery case can be dividedly reserved in the plurality of water reservoir portions  131 . Therefore, since water is dividedly collected in the water reservoir portions  131 , the water is prevented from moving in the auxiliary machinery case  130 , for example, even when the vehicle to which the fuel cell system is mounted performs a jack rabbit start, a sudden deceleration, a steep turn, etc. However, the present invention is not, limited to this structure, but may be provided with a single water reservoir portion  131 . 
         [0032]    The present invention is not limited to the embodiment and the modifications described above, and can be implemented in various structures without departing from the scope of the invention. For example, technical features in the embodiment and the modifications corresponding to technical features of each aspect cited in the section of “SUMMARY” can suitably be substituted and/or combined in order to address some or all of the subjects described above, or in order to obtain some or all of the effects described above. The technical features can suitably be deleted if the are not described as essential matters in this specification.