Abstract:
An electric automobile having a fuel cell system. A fuel tank, a fuel reformer, a fuel cell and an electrical energy storage constituting the fuel cell system are installed under the floor of the vehicle in their order as viewed longitudinally of its body. Thus, the components of the fuel cell system are arranged in accordance with its progression. This arrangement enables the shortening of piping and electrical wiring interconnecting the components.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an electric automobile having fuel cell as its power source, and more particularly, to an arrangement of a fuel tank, a fuel reformer, a fuel cell and an electrical energy storage which constitute a fuel cell system. 
     2. Description of the Related Art 
     A fuel cell is well known in the art, and an electric automobile having a fuel cell as its power source is known from, for example, Japanese Patent Laid-Open Publication No. HEI-3-109126 or U.S. Pat. No. 5,641,031. 
     The fuel-cell-powered electric automobile disclosed in Japanese Patent Laid-Open Publication No. HEI-3-109126 is a small electric automobile for a very small number of passengers, such as two, and has a fuel cell mounted in the vicinity of the center of gravity of its body. This electric automobile has, however, a narrow space in its passenger compartment, since the reformer, fuel cell and other batteries are installed on the frame of its body and these devices are situated in its passenger compartment. This arrangement of devices is undesirable for an automobile for four or five or more passengers, since it has a narrow passenger compartment. 
     The fuel-cell-powered electric vehicle disclosed in U.S. Pat. No. 5,641,031 is of the type not having any electrical energy storage. According to one example, the reformer and fuel tank constituting the fuel cell system are installed within the loading compartment in the rear region of the vehicle, but this arrangement has the drawback of narrowing the loading compartment. Shown as another example is an electric vehicle having a fuel tank mounted in its front region, a reformer mounted in its rear region, and a fuel cell mounted between the fuel tank and the reformer. According to this other example, however, the interconnection of the devices requires complicated piping, and the arrangement of the devices does not provide any efficient flow through the fuel cell system, but needs improvement. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of this invention to provide a fuel-cell-powered electric automobile for four or five or more passengers which makes it possible to realize an efficient arrangement of the components of its fuel cell system without narrowing the space in its passenger or loading compartment. 
     It is another object of this invention to provide a fuel-cell-powered electric automobile which makes it possible to realize an efficient arrangement of a distributor for distributing electric power generated by a fuel cell to an electrical energy storage and a motor in a fuel cell system, and an arrangement of its components which is beneficial for shortening their electrical wiring and simplifying the fabrication of the automobile including electrical wiring. 
     According to an aspect of this invention, there is provided a fuel-cell-powered electric automobile having a fuel cell as its power source, characterized in that a fuel tank, a fuel reformer, the fuel cell and an electrical energy storage are installed under its floor in their order as viewed longitudinally of its body. 
     According to this invention, therefore, the components of a fuel cell system including the fuel tank, reformer, fuel cell and electrical energy storage are arranged in the automobile body in accordance with progression through the system. Therefore, it is possible to shorten the piping and electrical wiring interconnecting the components, simplify the construction of the fuel-cell-powered electric automobile, facilitate its piping and wiring, and achieve an efficient arrangement of its fuel cell system. 
     Moreover, the components of the fuel cell system installed under the floor of the automobile body do not narrow the space in the automobile or its trunk compartment. Thus, the automobile and its trunk compartment have a broad space which is easy to use, and gives it an improved practical utility. 
     Moreover, the components of the fuel cell system are arranged longitudinally of the automobile in accordance with progression through the system. Therefore, the fuel cell and electrical energy storage which are greater in weight than the other components can be situated in the middle portion of the automobile, and the automobile has a good longitudinal balance of weight. 
     The electric automobile of this invention may further include a distributor installed in parallel to the electrical energy storage as viewed transversely of its body. Therefore, the electrical energy generated by the fuel cell can be supplied through the distributor to the motor in accordance with its load and to the electrical energy storage in accordance with the amount of energy stored therein. Moreover, the distributor is situated close to the electrical energy storage, and their electrical wiring can advantageously be shortened. 
     The automobile body has two longitudinally extending parallel frames which are appropriately spaced apart from each other along its width, and between which at least the reformer, fuel cell, electrical energy storage and distributor are installed. 
     Therefore, the frames protect the important components of the fuel cell system from any impact acting transversely upon the vehicle, and eliminate the necessity of providing any special protector for the fuel cell system or otherwise simplify the arrangement of such a protector. 
     A condenser is mounted on the top of the reformer for converting water vapor from the fuel cell to water. This arrangement allows water to enter the reformer by its own weight from the fuel cell, and eliminates the necessity of installing any special pump. etc. for supplying water to the reformer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Several preferred embodiments of this invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is a flowchart showing progression through a fuel cell system in a fuel-cell-powered electric automobile according to a first embodiment of this invention; 
     FIG. 2 is a top plan view of the automobile showing the arrangement of the components of the fuel cell system shown in FIG. 1, with a motor installed in the front portion of the automobile; 
     FIG. 3 is a side elevational view of the automobile shown in FIG. 2; 
     FIG. 4 is a top plan view of the automobile showing a layout of seats; 
     FIG. 5 is a side elevational view of the automobile shown in FIG. 4; 
     FIG. 6 is a flowchart showing progression through a fuel cell system in a fuel-cell-powered electric automobile according to a second embodiment of this invention; and 
     FIG. 7 is a top plan view of the automobile showing the arrangement of the components of the fuel cell system in a second embodiment shown in FIG. 6, with a motor installed in the front portion of the automobile. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description is merely exemplary in nature and is in no way intended to limit the invention, its application or uses. 
     FIG. 1 is a block diagram of the fuel cell system in a fuel-cell-powered electric automobile according to a first embodiment of this invention. The fuel cell system for a fuel-cell-powered electric automobile is known, and will be described briefly with reference to FIG.  1 . 
       1  is a fuel tank containing, for example, methanol as fuel, and  2  is a fuel reformer which heats a reactant material, such as a mixture of fuel from the fuel tank and water, thereby reforms it into a reformed gas consisting mainly of hydrogen and supplies it to a fuel cell  3 . 
     The fuel cell  3  is supplied with air (oxygen) from an air supply unit  4 , as well as with the reformed gas, and the reformed gas reacts with air (oxygen) to produce water (water vapor), while electricity is generated as is already known. The fuel cell  3  is equipped with a cooler  5 . 
     The electricity generated by the fuel cell  3  is supplied to a motor  6  as a source of motive power for an electric automobile for driving the motor  6  to cause the automobile to run. The electricity generated by the fuel cell  3  is also stored in an electrical energy storage  7 . The electrical energy storage  7  supplies electricity to the motor  6  in accordance with the operating conditions of the automobile. The electrical energy storage  7  may, for example, be a secondary battery, or electrical double-layer capacitor. 
     The water vapor produced and discharged by the fuel battery  3  is condensed by a condenser  8  into water, which water is supplied to the fuel reformer  2 . 
     Although methanol has been mentioned as an example of fuel, it is also possible to use gasoline. 
     FIGS. 2 and 3 are a top plan view showing by way of example an arrangement of the components of the fuel cell system shown in FIG. 1, with an electric automobile having a motor installed in its front portion. 
     The electric automobile  10  shown in FIG. 2 is a four-wheeled vehicle having a pair of front wheels  12  and a pair of rear wheels  13 . 
     An automobile body  11  shown by a two-dot chain line has two longitudinally extending frames  14  spaced apart from each other along the width of the vehicle. 
     The two frames  14  lie in a parallel and transversely spaced apart relation to each other. Each of the frames  14  as shown is composed of a front portion  14   a , a middle portion  14   b  and a rear portion  14   c . The middle portions  14   b  are situated substantially between the front wheels  12  and the rear wheels  13 . The front portions  14   a  have therebetween a spacing which is somewhat smaller than that between the middle portions  14   b . The rear portions  14   c  have inwardly curved portions  14   d  which are contiguous to the middle portions  14   b , respectively, and have therebetween a spacing which is smaller than that between the middle portions  14   b.    
     The components of the fuel cell system which have been described before with reference to FIG. 1 are installed longitudinally of the automobile  10  as described. 
     The fuel tank  1  is first installed in the rear portion of the automobile body  11 . More specifically, the fuel tank  1  is installed between the inwardly curved rear portions  14   d  of the frames  14 . The fuel reformer  2  is installed forwardly of, and adjacent to the fuel tank  1 . The condenser  8  is installed on the top of the reformer  2 , as shown in FIG.  3 . 
     The fuel cell  3  is installed forwardly of, and adjacent to the fuel reformer  2 . The electrical energy storage  7  is installed forwardly of, and adjacent to the fuel cell  3 . 
     The motor  6  is installed between the front portions  14   a  where the frames  14  have a smaller spacing therebetween. The motor  6  is installed in the front portion of the automobile body  11  forwardly of the electrical energy storage  7 . A transmission  6 a is connected to the motor  6 , as shown in FIG.  3 . The transmission  6   a  is connected to the front wheels  12  by a drive shaft (not shown). 
     The fuel reformer  2  carrying the condenser  8  on its top, the fuel cell  3  and the electrical energy storage  7  are installed between the middle portions  14   b  of the frames  14 , as described. They are arranged in the order of the reformer  2 , fuel cell  3  and electrical energy storage  7  as viewed from the rear portion of the automobile body  11  to its front portion. 
     The cooler  5  forming a cooling system for the fuel cell  3  is installed on the right-hand side of the fuel cell  3  and outwardly of the right frame  14 R. The air supply unit  4  forming an air intake system for the fuel cell  3  is situated on the left-hand side of the fuel cell  3  and outwardly of the left frame  14 L. 
     The front portions  14   a  of the frames  14  are at a somewhat higher level than the middle portions  14   b  are, as shown in FIG.  3 . The rear portions  14   c  are also at a somewhat higher level than the middle portions  14   b  are. The inwardly curved portions  14   d  of the rear portions  14   c  are somewhat curved upwardly, too. 
     FIGS. 4 and 5 show a layout of seats in the vehicle. 
     The two frames  14  are situated under the floor  15  of the automobile body  11 . 
     A pair of transversely spaced apart front seats  16  and  17  are mounted on a floor portion  15   a  above the fuel cell  3 . A rear seat  18  is mounted on a floor portion  15   b  situated backwardly of the floor portion  15   a , or above the fuel reformer  2 . A spare tire  19  is kept in a trunk compartment  11   d  defined above a floor portion  15   c  at the rear end of the automobile. 
     A radiator  20  for cooling the motor  6  is installed between the front ends of the frames  14  in the front portion of the automobile body  11 . A power control unit (PCU)  21  for controlling the motor and the fuel cell system is mounted above the motor  6  including the transmission  6   a.    
     The radiator  20 , the motor  6  including the transmission  6   a  and the power control unit  21  are situated in a motor room  11   b  closed by a bonnet  11   a  in the front portion of the automobile body  11 , as shown in FIG.  5 . 
     The fuel cell  3  is situated below the front seats  16  and  17  in a passenger compartment  11   c , as stated before. The fuel reformer  2  and the condenser  8  mounted thereon are located below the rear seat  18 . The fuel tank  1  is positioned behind the rear seat  18 , between the rear wheels  13 ,  13  and forwardly downwardly of the trunk compartment  11   d.    
     Although the motor  6  has been described as being situated in the front portion of the automobile, this invention is not limited to such arrangement, but the motor  6  may alternatively be situated in the rear portion of the automobile. In such a case, the fuel tank  1 , fuel reformer  2 , fuel cell  3  and electrical energy storage  7  are installed below the floor  15  in their order as viewed from the front portion of the automobile to its rear portion. 
     FIG. 6 shows a fuel cell system for a fuel-cell-powered electric automobile according to a second embodiment of this invention. The fuel cell system is shown by a flow diagram which is basically identical to FIG. 1 showing the first embodiment, and like numerals are used to denote like elements in both of the figures, so that no detailed description thereof may be repeated. 
     According to this second embodiment, a distributor  22  is installed between a fuel cell  3  and an electrical energy storage  7  and a motor  6 . The presence of the distributor  22  differentiates it from the fuel cell system according to the first embodiment. 
     The distributor  22  is provided for distributing the electric power generated by the fuel cell  3  and supplying it to the electrical energy storage  7  and the motor  6 . The distributor  22  supplies the electric power generated by the fuel cell  3  to the motor  6  in accordance with its load and to the electrical energy storage  7  in accordance with the amount of power stored therein. 
     For a specific example, electric power is supplied from the fuel cell  3  and the electrical energy storage  7  to the motor  6  when the motor  6  has a heavy load for accelerating the vehicle. 
     A power control unit (PCU)  21  is installed between the distributor  22  and the motor  6 . The PCU  21 , for example, controls the supply of electric power from the distributor  22  to the motor  6  and the fuel cell system (air supply unit, etc.) in accordance with the operating conditions of the automobile. It also controls the supply of regenerated power from the motor  6  to the electrical energy storage when the vehicle is driven under deceleration, or braked. 
     FIG. 7 shows by way of example an arrangement of the fuel cell system according to the second embodiment as described above in an electric automobile. 
     The arrangement of the components of the fuel cell system relative to an automobile body  11  is basically identical to that according to the first embodiment as described before, and like numerals are used to denote like parts throughout the relevant figures, so that no detailed description may be repeated. 
       10  is an electric automobile,  11  is an automobile body,  12  are a pair of transversely spaced apart front wheels,  13  are a pair of transversely spaced apart rear wheels, and  14  are frames. 
     The right and left frames  14 R and  14 L are situated in a parallel and transversely spaced apart relation to each other, as stated in the description of the first embodiment. The fuel tank  1 , fuel reformer  2 , condenser  8 , fuel cell  3 , electrical energy storage  7  and motor  6  constituting the fuel cell system are installed between the two frames  14  in their order as viewed from the rear portion of the automobile body  11  to its front portion, as stated in the description of the first embodiment shown in FIGS. 2 and 3. The motor  6  is provided with a transmission not shown, as according to the first embodiment. 
     According to this second embodiment, the distributor  22  is situated on the right-hand side of the electrical energy storage  7  ahead of the fuel cell  3  in parallel and close proximity thereto. 
     The second embodiment is also applicable to an electric automobile having a motor  6  installed in the rear portion of its body  11 , as the first embodiment is. In such a case, the fuel tank  1 , fuel reformer  2 , fuel cell  3 , and electrical energy storage  7  including the distributor  22  installed on one side thereof are installed below the floor of the automobile body  11  in their order as viewed from its front to rear portion. 
     Obviously, various minor changes and modifications of the present invention are possible in the light of the above teaching. It is therefore to be understood that without the scope of the appended claims the invention may be practiced otherwise than as specifically described.