JSAE Exposition 2015: Toyota Mirai FCV cutaway model on display

Suppliers include Toyota Boshoku, Toyota Industries, Denso, Aisin, JTEKT, Aisan, and Toray



 During the Automotive Engineering Exposition 2015 held on May 20-22 by the Society of Automotive Engineers Japan (JSAE), Toyota Motor Corporation exhibited a cutaway model of the "Mirai" Fuel Cell Vehicle ("Mirai" FCV) that was released for sale in December 2014. Toyota Group suppliers exhibited fuel cell stacks, hydrogen tanks and other FCV parts and technologies in their booths as outlined below.

Toyota Mirai FCV Toyota Mirai FCV engine room Cutaway model of the Toyota Mirai FCV
Toyota "Mirai" FCV Toyota "Mirai" FCV engine room: Power control unit and motor Cutaway model of the Toyota "Mirai" FCV: The FC stack is placed under the front seat, the hydrogen fuel tank under the rear seat, and the rechargeable secondary drive battery and hydrogen fuel tank behind the rear seats.

Main parts for Toyota Mirai exhibited

Fuel cell stack parts Stack manifold Toyota Boshoku
Ion exchanger
Air compressor Toyota Industries
Hydrogen circulation pump
Inverter for hydrogen circulation pump
Air valve module Aisin Seiki
Terminal (power collector part) Aisin Takaoka
Electrode material Toray
FC stack cooling system (radiator, electric water pump, etc.) Denso
Hydrogen injector Aisan Industry
Hydrogen supply parts High-pressure hydrogen supply valve JTEKT
Pressure-reducing valve
Hydrogen filling system parts (high-pressure sensor, infrared transmitter, etc.) Denso
Carbon fiber for hydrogen tank Toray
Other parts Seat, door panel Toyota Boshoku
Stack frame Toray

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FCV reports
Toyota's technologies in Mirai FCV (Apr. 2015)
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Toyota Boshoku: Stack manifold, separator, ion exchanger, seat and door panel


Stack manifold Separator
Stack manifold Separator: Top and bottom holes are air passages, three identical holes at sides are water passages and the fourth holes are passages for hydrogen.


Stack manifold The pipe to supply hydrogen, air and cooling water to the FC stack on the "Mirai" FCV are supplied by Toyota Boshoku. Aluminum and resin parts of different stretching properties were made thinner by insert molding.
Separator The separator of the FC hydrogen electrode has a fine passage formed by titanium. Titanium has an expansion ratio of around 30% but Toyota Boshoku succeeded in increasing it to 60% by using its "high precision, high-speed press-molding process" (by striking and stretching in the molding process although details are not disclosed).
Ion exchanger The ion exchanger removes impurity ions from the FC cooling water to keep the stack electrically insulated.
Seat, door panel The company also supplies seats and door panels for the "Mirai" FCV.
Ion exchanger Seat, door panel
Ion exchanger: Cooling water enters the exchanger from bottom and flows upward. The pipe connection at the bottom is offset from the center so that the ion exchange resins are stirred by the in-flowing water. Seat, door panel for the Mirai



Toyota Industries: Air compressor, hydrogen circulation pump and inverter


Air compressor Hydrogen circulation pump
Air compressor Hydrogen circulation pump

Roles of the air compressor and the hydrogen circulation pump

Roles of the air compressor and the hydrogen circulation pump

Source: Toyota Motor Corporation


Air compressor The air compressor compresses the air (oxygen) and feeds it to the FC stack for electric power generation. Air compression is achieved by a six-lobe 120-degree helical root type rotor. The compression efficiency has been improved by regulating the airflow pressure between low during idling and high during acceleration. The efficiency has been increased by 14% (low airflow) and 20% (high airflow) compared to the previous model (FCHV-adv launched by Toyota for lease sales in 2008).
Vibration damping steel and sound muffling structure is used to reduce unpleasant noise and improve the smooth acceleration feel. The acoustic pressure has been reduced by 44% from the previous model. Since no internal combustion engine is used, the sound of the air compressor is the only operating sound heard by the driver of the "Mirai" FCV.
Hydrogen circulation pump The pump is used to recirculate unreacted hydrogen and water in the FC stack. Highly-efficient recirculation in the hydrogen electrode side has led to the world's first FC stack without a humidifier (in conventional methods, the humidity in the stack is increased by humidifying the air being fed by the air compressor in the air electrode side:  Please click here for more detail).
Inverter for hydrogen circulation pump The inverters for the hydrogen circulation pump and for the water pump have been integrated as a single unit. This enables sharing the cooling water passage and supply of electricity which contributes to 23% downsizing from the previous model.
Inverter for hydrogen circulation pump
Inverter for hydrogen circulation pump



Denso: Cooling parts and hydrogen filling system parts


Cooling parts, hydrogen filling system parts
Cooling parts, hydrogen filling system parts


Cooling parts/ hydrogen filling system parts Denso supplies many parts for the Toyota "Mirai" FCV such as the cooling system for the FC stack (radiator, electric water pump, etc.) and parts for filling hydrogen in the hydrogen tank (high-pressure sensors, infrared ray transmitters, etc.). The company exhibited some of them in relation to the entire system configuration.



Aisin Group: Air valve module and terminals

Air valve module Terminals
Air valve module Terminals: The terminal with a rectangular hole is the negative electrode terminal (in the foreground). The positive electrode terminal is shown in the back.


Air valve module Parts that regulate the air supply to the FC stack are modularized according to pressure governing, diverging and sealing functions. When the accelerator is activated calling for electric power generation, the valve is opened to feed air to the FC. The air flow is diverged according to the accelerator opening to regulate the amount of air feed and change the amount of electric generation. When electric generation is not needed, the valve is sealed so that no air is supplied to the stack.
Terminals These terminals, supplied by Aisin Takaoka, are electric power collection parts in the FC stack. Their surface is treated to reduce electric resistance and withstand corrosive environment in the FC stack more effectively.



JTEKT: Hydrogen supply valve and pressure-reducing valve


High-pressure hydrogen valve Pressure-reducing valve
High-pressure hydrogen valve Pressure-reducing valve


JTEKT High-pressure hydrogen supply valve The valve seals or supplies the pressurized hydrogen in the hydrogen tank.
Pressure-reducing valve The pressure-reducing valve reduces the hydrogen supply valve pressure from 70MPa to 1MPa for use in the FC stack.



Aisan Industry: Hydrogen injectors

Hydrogen injectors for FCV
Hydrogen injectors for FCV
Hydrogen injectors for FCV The injectors regulate the hydrogen pressure and flow rate to the FC stack.



Toray: Carbon fibers for Mirai FCV


Hydrogen tank on Mirai FCV Parts where Toray carbon fibers are used
Hydrogen tank on "Mirai" FCV made of Toray carbon fibers Parts where Toray carbon fibers are used (source: Toray press release)


High-strength carbon fibers for high-pressure hydrogen tanks High-strength carbon fibers characterized by safety, strength and light weight are used in the hydrogen tanks for the "Mirai" FCV.
Carbon paper for electrode material (for gas diffusion) in the FC stack Carbon paper meets gas diffusion, durability and other requirements and contributes to improving the FC stack performance and space saving.
Carbon fiber reinforced thermoplastic (CFRTP) developed for automotive structural parts The press-moldable CFRTP, co-developed with Toyota, is used in the "stack frame" (equivalent to the vehicle floor) that protects the FC.

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