Patent Publication Number: US-2005139402-A1

Title: Fuel cell vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This is a continuation of Application No. PCT/JP03/08215, filed on Jun. 27, 2003, now abandoned. 
    
    
     BACKGROUND ART  
      1. Technical Field  
      The present invention relates to a fuel cell vehicle with fuel cells mounted thereon.  
      2. Prior Art to be Disclosed  
      Fuel cell vehicles having various arrangements of fuel cells without narrowing a passenger compartment have been proposed. For example, a fuel cell vehicle disclosed in Japanese Patent Laid-Open Gazette No. 2001-253248 has a drive motor and fuel cells arranged in a front vehicle chamber. The drive motor is located about the center of an axle spanned between left and right front wheels. The fuel cells are arranged close to the drive motor. Fuel tanks for supplying a fuel gas (hydrogen) to the fuel cells are also arranged close to the fuel cells.  
      In this prior art fuel cell vehicle disclosed in the above cited reference, only one drive motor is used to rotate both the left and the right wheels. The drive motor accordingly has relatively large dimensions to narrow the space for the fuel cells. The arrangement of the fuel tanks close to the fuel cells undesirably restricts the layout.  
      The object of the invention is thus to eliminate the drawbacks of the prior art and to provide a fuel cell vehicle with fuel cells placed with some margins in a relatively large space between left and right wheels. The object of the invention is also to provide a fuel cell vehicle with vehicle equipment arranged in a favorable layout via sufficient intervals.  
     SUMMARY OF THE INVENITON  
      In order to attain at least part of the above and the other related objects, the present invention is directed to a first fuel cell vehicle including: a left wheel motor and a right wheel motor that are located respectively close to at least one of left wheels and close to at least one of right wheels on a front side and a rear side of the fuel cell vehicle; and fuel cells that are placed in a space formed between the left and right wheels on either of the front side and the rear side of the fuel cell vehicle.  
      In the first fuel cell vehicle of the invention, the left wheel motor and the right wheel motor are located close to the left and right wheels on the front side of the vehicle, close to the left and right wheels on the rear side of the vehicle, or close to the left and right wheels on both the front side and the rear side of the vehicle. The fuel cells are arranged in the space formed between the left and right wheels on the front side of the vehicle or in the space formed between the left and right wheels on the rear side of the vehicle. In the arrangement of the fuel cells in the space formed between wheels without the nearby wheel motors, the fuel cells are placed with some margins in this sufficiently large space. In the arrangement of the fuel cells in the space formed between the wheels with the nearby wheel motors, on the other hand, the left wheel motor and the right wheel motor respectively driven to rotate the left wheel and the right wheel have smaller dimensions, compared with a common motor driven to rotate both the left wheel and the right wheel. Such small dimensions ensure a relatively large space between wheels, in which the fuel cells are placed with some margins. The fuel cells may be arranged to be wholly received in the space formed between the wheels or to be partly extended to the space formed between the wheels.  
      The ‘fuel cells’ may be arranged to supply electric power to the left wheel motor and the right wheel motor or to supply electric power to other vehicle equipment (for example, air conditioning equipment, audio video equipment, a navigational device, and a lighting device).  
      In the fuel cell vehicle of the invention, the fuel cells may be placed in an inter-motor space formed between the left wheel motor and the right wheel motor. The left wheel motor is arranged close to the left wheel, whereas the right wheel motor is arranged close to the right wheel. There is accordingly a space between the two motors (inter-motor space). The left wheel motor and the right wheel motor respectively driven to rotate the left wheel and the right wheel have smaller dimensions, compared with a common motor driven to rotate both the left wheel and the right wheel. Such small dimensions ensure a relatively large inter-motor space, in which the fuel cells are placed with some margins. The fuel cells may be arranged to be wholly received in the inter-motor space or to be partly extended to the inter-motor space.  
      In the fuel cell vehicle of the invention, the fuel cells may be placed on the front side of the fuel cell vehicle. The arrangement of the fuel cells on the front side of the vehicle is convenient for replacement or repair.  
      In the fuel cell vehicle of the invention, the left wheel motor and the right wheel motor may be both in-wheel motors. This arrangement ensures a sufficiently large inter-motor space.  
      In one preferable embodiment of the fuel cell vehicle of the invention, at least part of auxiliary machinery of the fuel cells is placed in a neighborhood of the fuel cells. This arrangement desirably simplifies the wiring and piping connections with the fuel cells, compared with separate arrangement of at least part of the auxiliary machinery from the fuel cells. The ‘auxiliary machinery of the fuel cells’ represent various devices and equipment required for the operations of the fuel cells and include an oxidizing gas supply device to supply an oxidizing gas to the fuel cells, a fuel gas supply device to supply a fuel gas to the fuel cells, mass flow controllers to regulate the pressures and the flow rates of the oxidizing gas and the fuel gas supplied to the fuel cells, gas circulation devices to recirculate non-reacted oxidizing gas and non-reacted fuel gas, which are discharged from the fuel cells, to the fuel cells, and a cooling water circulation device to circulate cooling water through the fuel cells for cooling the fuel cells down.  
      The fuel cell vehicle of the invention may further include a secondary battery that is located in a lower space under a seat in a passenger compartment of the fuel cell vehicle. The lower space of the seat is not occupied by the fuel cells and can thus receive the secondary battery therein. The secondary battery may be arranged inside a vehicle chamber (on the vehicle floor) or outside the vehicle chamber (below the vehicle floor). It is preferable that the secondary battery is positioned by underfloor reinforcements, which are extended in a longitudinal direction of the fuel cell vehicle, and is oriented to have its longitudinal axis parallel to a side-to-side horizontal direction of the fuel cell vehicle. This arrangement utilizes the underfloor reinforcements generally provided in the vehicle to position the secondary battery, thus desirably reducing the number of fixtures to fasten the secondary battery and enhancing the rigidity of the vehicle against side collisions. The ‘secondary battery’ may be arranged to supply electric power to the left wheel motor and the right wheel motor or to supply electric power to other vehicle equipment (for example, air conditioning equipment, audio video equipment, a navigational device, and a lighting device). The secondary battery may be replaced with a chargeable and dischargeable accumulator, for example, a capacitor.  
      The fuel cell vehicle of the invention may further include a fuel gas supply source that is located in a lower space under a seat in a passenger compartment of the fuel cell vehicle and supplies a fuel gas to the fuel cells. The lower space of the seat is not occupied by the fuel cells and can thus receive the fuel gas supply source therein. The ‘fuel gas supply source’ may be any device that is capable of supplying a fuel gas subjected to electrochemical reaction of the fuel cells, for example, a container for storage of the fuel gas or a generator for generating the fuel gas from a certain material.  
      The present invention is also directed to a second fuel cell vehicle including: fuel cells that are located in a front vehicle chamber; a secondary battery that is located in a lower space under a front seat in a passenger compartment of the fuel cell vehicle; and a fuel gas supply source that is located in a lower space under a rear seat in the passenger compartment and supplies a fuel gas to the fuel cells.  
      In the second fuel cell vehicle of the invention, the fuel cells, the secondary battery, and the fuel gas supply source as vehicle equipment are arranged in this order via intervals from the front to the rear of the vehicle. This structure ensures the favorable layout of the vehicle equipment via sufficient intervals. The fuel cells and the secondary battery of the high-voltage power source system are sufficiently separated from the fuel gas supply source. The fuel cells and the secondary battery may be identical with the fuel cells and the secondary battery included in the first fuel cell vehicle of the invention. This ensures the additional functions and effects of the first fuel cell vehicle. In a vehicle with three rows of seats aligned in the longitudinal axis of the vehicle, when a seat in a front row is defined as a front seat, a seat in either a middle row or a rear row is set to a rear seat. When the seat in the middle row is defined as the front seat, on the other hand, the seat in the rear row is set to the rear seat. The secondary battery may be replaced by a chargeable and dischargeable accumulator, for example, a capacitor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a plan view schematically illustrating the configuration of a fuel cell vehicle in one embodiment of the invention;  
       FIG. 2  is a side view schematically illustrating the configuration of the fuel cell vehicle of the embodiment;  
       FIG. 3  is a block diagram showing the internal structure of the fuel cell vehicle of the embodiment;  
       FIG. 4  shows an arrangement of a secondary battery; and  
       FIG. 5  shows another arrangement of the secondary battery. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      In order to clarify the objects, features, aspects, and advantages of the present invention, one mode of carrying out the invention is described below with reference to the accompanied drawings.  FIG. 1  is a plan view schematically illustrating the configuration of a fuel cell vehicle in one embodiment of the invention;  FIG. 2  is a side view schematically illustrating the configuration of the fuel cell vehicle of the embodiment;  FIG. 3  is a block diagram showing the internal structure of the fuel cell vehicle of the embodiment.  
      The fuel cell vehicle  10  of this embodiment has a monocoque chassis construction of integrated chassis frame and body and mainly includes a left wheel motor  11 , a right wheel motor  12 , a front seat  14 , a rear seat  16 , fuel cells  20 , a secondary battery  40 , hydrogen tanks  21 , and a power control unit (PCU)  50 . The monocoque chassis construction may be replaced by a frame construction. The PCU  50  is omitted from the illustration of  FIG. 2 .  
      The left wheel motor  11  is an in-wheel motor built inside the wheel structure of a left front wheel FLW and functions to rotate an axle of the left front wheel FLW. The right wheel motor  12  is an in-wheel motor built inside the wheel structure of a right front wheel FRW and functions to rotate an axle of the right front wheel FRW. The left wheel motor  11  and the right wheel motor  12  are separately arranged to define a relatively wide inter-motor space S therebetween in a front vehicle chamber  61 , which is parted from a passenger compartment  62  by a dash panel. The inter-motor space S is a virtual cavity space defined by connecting a contour shape of the left wheel motor  11  seen from a side-to-side horizontal direction of the vehicle under the setting of the left front wheel FLW in a traveling direction with a contour shape of the right wheel motor  12  seen from the side-to-side horizontal direction of the vehicle under the setting of the right front wheel FRW in the traveling direction.  
      A DC power output from the fuel cells  20  or the secondary battery  40  goes through a distributor  27  and is converted into three-phase alternating currents by inverters  11   a  and  12   a  to be supplied to the respective motors  11  and  12  as shown in  FIG. 3 . In response to the supply of the electric power, both the motors  11  and  12  generate rotational driving forces, which are respectively transmitted to the axles of the left front wheel FLW and the right front wheel FRW to be used as the power of driving the fuel cell vehicle  10 .  
      The front seat  14  is a seat in a front row out of two rows of seats provided in the passenger compartment  62  and includes a driver&#39;s seat and a front passenger&#39;s seat. A floor face  70  of the vehicle rises just below the front seat  14 , and the front seat  14  is located on the rise or a step plane  71 . A space formed between the step plane  71  and a reference plane  74  for setting of the ground clearance defines a lower space  63  of the front seat  14 . The secondary battery  40  is placed in the lower space  63 . The rear seat  16  is a bench seat in a rear row out of the two rows of seats. The floor face  70  of the vehicle also rises just below the rear seat  16 , and the rear seat  16  is located on the rise or a step plane  72 . A space formed between the step plane  72  and the reference plane  74  defines a lower space  64  of the rear seat  16 . The hydrogen tanks  21  are placed in the lower space  64 . In the structure of this embodiment, a partition  73  for a trunk space  65  is extended from the step plane  72 . A space defined by the partition  73  and the reference plane  74  is included in the lower space  64  of the rear seat  16 .  
      The fuel cells  20  are placed in the front vehicle chamber  61  to be partly extended to the inter-motor space S as shown in  FIGS. 1 and 2 . The fuel cells  20  are known polymer electrolyte fuel cells and form a stack structure including a large number of unit cells to function as a high-voltage power source (several hundred volts). As shown in  FIG. 3 , in each unit cell of the fuel cells  20 , an anode receives a supply of hydrogen gas (fuel gas), which is fed from the hydrogen tank  21 , goes through a mass flow controller  22  for pressure and flow rate control, and is humidified by a humidifier  23 , while a cathode receives a supply of pressure-regulated, compressed air (oxidizing gas) from an air compressor  13 . The fuel cells  20  produce an electromotive force through electrochemical reaction of the hydrogen gas with the compressed air. Hydrogen is separated into proton and electron at the anode. The proton separated at the anode is transmitted through a polymer electrolyte membrane and reaches the cathode, while the electron separated at the anode runs through a connected electric circuit via a load and also reaches the cathode. Oxygen included in the compressed air reacts with the proton and the electron to produce water at the cathode. This electrochemical reaction generates an electromotive force.  
      Auxiliary machinery of the fuel cells  20  include the air compressor  13 , the hydrogen tanks  21 , the mass flow controller  22 , the humidifier  23 , a DC/DC converter  24  actuated to lower the output voltage of the fuel cells  20  or the secondary battery  40  to a preset voltage level, a hydrogen gas circulation pump  25  driven to recirculate non-reacted hydrogen gas exhaust, which is discharged from the fuel cells  20 , to the fuel cells  20 , a water pump  26  used to circulate a flow of cooling water through the fuel cells  20  for cooling the fuel cells  20  down, the distributor  27  used to distribute the outputs of the fuel cells  20  and the secondary battery  40 , and a radiator  32  used to remove heat from the cooling water circulated through the fuel cells  20  by the water pump  26 . The distributor  27  is a switching circuit to give a power supply from either one or both of the fuel cells  20  and the secondary battery  40  to the respective wheel motors  11  and  12  and to charge the secondary battery  40  with electric power of the fuel cells  20 .  
      The electric power output from the fuel cells  20  and/or the secondary battery  40  is transmitted via the distributor  27  to the DC/DC converter  24  for voltage drop to a preset level and is supplied to the air compressor  13 , the mass flow controller  22 , the humidifier  23 , the hydrogen gas circulation pump  25 , the water pump  26 , and a cooling fan of the radiator  32  among the auxiliary machinery. The air compressor  13 , the mass flow controller  22 , the humidifier  23 , the DC/DC converter  24 , the hydrogen gas circulation pump  25 , the water pump  26 , the distributor  27 , and the radiator  32  among the auxiliary machinery are placed in the front vehicle chamber  61  with the fuel cells  20  located therein. The air compressor  13  is arranged to be partly extended to the inter-motor space S.  
      The secondary battery  40  includes plurality of known nickel metal hydride cells connected in series to function as a high-voltage power source (several hundred volts). The secondary battery  40  under control of the PCU  50  drives the respective wheel motors  11  and  12  at a start of the vehicle, recovers a regenerative electric power in decelerating regenerative control, assists the wheels motors  11  and  12  in acceleration, and is charged according to the loading state by the fuel cells  20 . The secondary battery  40  is not restricted to the nickel metal hydride battery but may be any chargeable and dischargeable battery, for example, a nickel cadmium battery, a lithium metal hydride battery, or a lead-acid battery. The secondary battery  40  may be replaced by a capacitor.  
      The secondary battery  40  is positioned by a pair of underfloor reinforcements  66  and  67 , which are extended on left and right sides of the vehicle in a longitudinal direction of the vehicle, in the lower space  63  of the front seat  14  and is oriented to have its longitudinal axis parallel to the side-to-side horizontal direction of the vehicle. The underfloor reinforcements  66  and  67  are members of the monocoque chassis construction of the fuel cell vehicle  10 . In the structure of this embodiment, the height of the secondary battery  40  is greater than the interval between the underfloor reinforcements  66  and  67  and the step plane  71  of the front seat  14 . A bridge member  68  is thus provided to bridge the lower portions of the pair of the underfloor reinforcements  66  and  67  as shown in  FIG. 4 . The secondary battery  40  is fastened onto the bridge member  68 .  FIG. 4 ( a ) is a side view in the vicinity of the front seat  14 , and  FIG. 4 ( b ) is its front view. In the case where the whole secondary battery  40  is receivable in the interval between the underfloor reinforcements  66  and  67  and the step plane  71  of the front seat  14 , the secondary battery  40  is fastened to be spanned between the pair of underfloor reinforcements  66  and  67 , as shown in  FIG. 5 .  FIG. 5 ( a ) is a side view in the vicinity of the front seat  14 , and  FIG. 5 ( b ) is its front view. The secondary battery  40  is located outside the passenger compartment (below the floor of the vehicle) in the examples of  FIGS. 4 and 5 . The secondary battery  40  may alternatively be located inside the passenger compartment (above the floor of the vehicle). In one modified structure, the secondary battery  40  may be located in a recess of a floor panel, which is formed below the front seat  14  and is covered with a hat-like lid including the step plane  71 .  
      The PCU  50  functions to control the driving forces of the left wheel motor  11  and the right wheel motor  12  and is constructed as a microcomputer-based logic circuit of a known structure (not shown) including a CPU, a ROM, a RAM, and input/output ports. The PCU  50  is located above the front vehicle chamber  61 . The PCU  50  receives inputs of an accelerator opening from an accelerator pedal position sensor (not shown), output current and voltage levels of the inverters  11   a  and  12   a,  an SOC (state of charge) of the secondary battery  40 , and measurements of diverse sensors (not shown), and outputs control signals based on these inputs to the mass flow controller  22  and the air compressor  13  for regulation of the gas supply flows and to the inverters  11   a  and  12   a  and the distributor  27 .  
      In the fuel cell vehicle  10  of this embodiment constructed as discussed above, the left wheel motor  11  and the right wheel motor  12  are provided respectively as the in-wheel motors to rotate the left front wheel FLW and the right front wheel FRW. Compared with a common motor used to rotate both the left front wheel FLW and the right front wheel FRW, the wheel motors  11  and  12  have smaller dimensions to define a relatively large space as the inter-motor space S in the front vehicle chamber  61 . The fuel cells  20  are placed with some margins in this inter-motor space S.  
      The fuel cells  20  are located on the front side of the vehicle to be readily replaced and repaired through a hood.  
      Among the auxiliary machinery of the fuel cells  20 , the air compressor  13  (the oxidizing gas supply device), the mass flow controller  22 , the hydrogen gas circulation pump  25  (the fuel gas circulation device), the water pump  26  (the cooling water circulation device), the distributor  27 , and the radiator  32  are located in the front vehicle chamber  61  with the fuel cells  20  placed therein. This arrangement desirably simplifies the wiring and piping connections with the fuel cells  20 , compared with separate arrangement of these auxiliary machines from the fuel cells.  
      The lower space  63  of the front seat  14  is effectively used to locate the secondary battery  40 . The secondary battery  40  is positioned by the underfloor reinforcements  66  and  67 , which are extended in the longitudinal direction of the vehicle, and is oriented to have its longitudinal axis parallel to the side-to-side horizontal direction of the vehicle. This arrangement desirably reduces the number of fixtures to fasten the secondary battery  40  and enhances the rigidity of the vehicle against side collisions. The secondary battery  40  may be located in a vehicle chamber to be protected from dust.  
      The lower space  64  of the rear seat  16  (including the lower space under the partition  73  of the trunk space  65 ) is effectively used to locate the hydrogen tanks  21 . The fuel cells  20 , the secondary battery  40 , and the hydrogen tanks  21  are thus arranged in this order via sufficient intervals from the front to the rear of the vehicle. The fuel cells  20  and the secondary battery  40  of the high-voltage power source system are desirably separated from the hydrogen tanks  21 .  
      The embodiment discussed above is to be considered in all aspects as illustrative and not restrictive. There may be many other modifications, changes, and alterations without departing from the scope or spirit of the main characteristics of the present invention.  
      For example, the fuel cell vehicle of the embodiment has the two rows of seats in the passenger compartment  62  aligned in the longitudinal axis of the vehicle. Three or a greater number of rows of seats may be provided in the passenger compartment of the vehicle. For example, in a vehicle with three rows of seats, when a seat in the front row is defined as the front seat, a seat in either the middle row or the rear row is set to the rear seat. When the seat in the middle row is defined as the front seat, on the other hand, the seat in the rear row is set to the rear seat. In another vehicle with only one row of seat in the passenger compartment  62 , the secondary battery  40  may be placed in a lower space of the seat, while the hydrogen tanks  21  may be placed in the lower space under the partition  72  of the trunk space  65 .  
      In the fuel cell vehicle of the embodiment, the hydrogen tanks  21  are used as the source of the hydrogen gas (fuel gas) supplied to the fuel cells  20 . The hydrogen tanks  21  may be replaced by a hydrogen storage alloy or by a reformer that produces hydrogen-rich gas through reaction of a hydrocarbon fuel (for example, gasoline or methanol) with water.  
      The above embodiment regards the front-wheel drive vehicle. The principle of the invention is also applicable to a rear-wheel drive vehicle or to a four-wheel drive vehicle. In the rear-wheel drive vehicle, in-wheel motors are provided to respectively rotate a left rear wheel and a right rear wheel, and the fuel cells  20  are placed in a space formed between the two in-wheel motors (inter-motor space). In the four-wheel drive vehicle, the fuel cells  20  may be arranged in an inter-motor space on either the front wheels or the rear wheels.  
      In the fuel cell vehicle of the embodiment, the fuel cells  20  are arranged to be partly extended to the inter-motor space S in the front vehicle chamber  61 . The fuel cells  20  may be arranged to be wholly received in the inter-motor space S.  
      In the fuel cell vehicle of the embodiment, both the fuel cells  20  and the secondary battery  40  are used as the available power source of the respective wheel motors  11  and  12 . (In this structure, the control may give the power supply from both of the fuel cells  20  and the secondary battery  40  to the wheel motors  11  and  12  or may give the power supply from only one of the fuel cells  20  and the secondary battery  40  to the wheel motors  11  and  12 ). In one possible modification, only one of the fuel cells  20  and the secondary battery  40  may be used as the available power source of the wheel motors  11  and  12 . For example, one of the fuel cells  20  and the secondary battery  40  is used as the power source of the wheel motors  11  and  12 , while the other is used as the power source of other equipment (for example, auxiliary machinery). Another modified structure has another power source for the wheel motors  11  and  12  in addition to the fuel cells  20  and the battery  40 , and uses both or either one of the fuel cells  20  and the battery  40  to assist the additional power source. The wheel motors  11  and  12  are structured to use at least one of the fuel cells  20  and the secondary battery  40  as the available power source.  
      In the fuel cell vehicle of the embodiment, the left wheel motor  11  and the right wheel motor  12  are respectively provided as the in-wheel motors attached to the left front wheel FLW and to the right front wheel FRW. In one modified structure, the fuel cells  20  may be arranged in the front portion of the vehicle, and the left wheel motor  11  and the right wheel motor  12  may be provided as in-wheel motors attached to a left rear wheel and to a right rear wheel. The fuel cells  20  are thus placed with some margins in a sufficiently large space formed between the left front wheel FLW and the right front wheel FRW, since no wheel motors are located in this space.  
      Industrial Applicability  
      The technique of the invention is applicable to automobile industries.