FCX 2002.12.2

System combines a fuel cell stack and ultra-capacitor
with an onboard high-pressure hydrogen tank
A fuel cell vehicle is powered by an electric motor running on electricity generated by a fuel cell stack using hydrogen as its energy source. There are a number of methods for creating such a powertrain. The principal methods for supplying the hydrogen include those in which it is stored directly onboard the vehicle and those in which a reformer is used to convert methanol or gasoline into hydrogen. There are also various methods for storing hydrogen onboard the vehicle. In terms of power supply, some systems use power output from the fuel cell stack alone to drive the motor, while others supplement the FC stack output with an assist mechanism using a battery or capacitor. After considering a variety of factors, such as energy efficiency during power generation and driving, overall system weight, and packaging efficiency, Honda decided to equip the FCX with a system that combines a fuel cell stack and ultra-capacitor with an onboard high-pressure hydrogen tank.
Drive system configuration comparison
Components laid out for efficient use of overall vehicle space
The powertrain of a fuel cell vehicle has more structural components than a gasoline-powered vehicle does, and they weigh more and take up more space. On the other hand, components apart from the drive mechanism can be laid out freely, and their positioning has a significant effect on the car's performance. For the FCX, Honda developed a custom platform for optimum positioning of the various components, while making each one as compact and lightweight as possible. Starting with the FC stack, which is the heaviest component, power-generating equipment was centrally located under the floor, while the hydrogen tank was tucked beneath the rear seat and the ultra-capacitor installed behind the rear seat. This layout significantly contributes to comfort and performance by ensuring plenty of cabin space and luggage space, while at the same time achieving a low center of gravity and the optimum front-rear weight distribution for a front-wheel-drive vehicle.
Main powertrain components
· Fuel cell stack
PEFC (polymer electrolyte fuel cell) electrical generation device.
Lightweight, compact, with a maximum output of 78kW.
· High-pressure hydrogen supply system
Equipped with two tanks. Can be filled with up to 156.6L of hydrogen at approximately 350 atmospheres.
· Air supply system
An air pump with a high-voltage electric drive motor supplies the FC stack with air at the appropriate pressure and flow rate.
· Humidification system
The recycled-water-recovery (fully independent) humidification system recycles water vapor generated in the FC stack for use in hydrogen and air humidification.
· Fuel cell cooling system
Equipped with one fuel cell system radiator (large) specially developed for use in fuel cell vehicles and two drive train radiators (small), for improved cooling performance.
· Honda ultra-capacitor
Delivers instantaneous high-output assist during startup and acceleration, while also efficiently recovering energy generated during braking. Combines high responsiveness with high efficiency.
· Drive train
Composed of a drive motor, transmission, and drive shaft. The newly developed drive motor combines high efficiency with high output and torque (maximum output: 60kW; maximum torque: 272Nm).
· PCU (power control unit)
Controls electrical systems, including FC stack output, capacitor output, drive motor output, air pump, and cooling pump.


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