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Direct methanol fuel cell (DMFC) system is a compact lightweight system as it eliminates the need of a complex reformer unit. Moreover, since the methanol-water-solution used as fuel does not correspond to a flammable substance, it is thought that convenience is high. We have developed the hybrid scooter integrated with the DMFC system and the Li-ion rechargeable batteries, and optimized various parameters related to the performance and the efficiency. The power output of the DMFC system was adjusted to the value necessary for a constant ground run in 30 km/h of a commercial small electric scooter. All the system components had to be constituted in the limited space and under the restricted weight conditions. The net-power-output of the system was examined under various air flow rate, fuel flow rate and methanol concentration conditions.

The Bonded Valve Seat System is the latest technology to realize drastic reduction in valve temperature in SI engines characterized by the good thermal conductivity of extremely thin valve seats bonded directly on the aluminum cylinder head. A unique and highly rationalized resistance bonding technique was developed to maintain adequate bonding strength and positioning precision in a short bonding period of around one second. Engineering data on optimization of bonding-section geometry, valve seat material and the surface treatment and bonding parameters were presented and discussed regarding the mechanism. The geometry of the bonding section of the cylinder head was optimized by FEM analysis so that the aluminum material should deform to embed the valve seat ring with the action of expelling the surface contamination and the oxide film. The bonding facility was modified so that the electrode axis should move flexibly according to distortion of the cylinder head during bonding.