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Toyota Motor Corporation began leasing a new generation fuel cell vehicle the FCHV (Fuel Cell Hybrid Vehicle) in December 2002. That vehicle includes a new variable voltage power electronics system and uses the Nickel Metal Hydride (Ni-MH) battery system from the Prius hybrid gasoline electric vehicle. This paper describes on-going efforts to model optimum secondary storage systems for future vehicles. Efficiency modeling is presented for the base Ni-MH storage system, an ultra capacitor system and a Lithium ion (Li-ion) battery system. The Li-ion system in combination with a new high efficiency converter shows a 4% improvement in fuel economy relative to the base system. The ultra capacitor system is not as efficient as the base system.

An exhaust air fuel ratio sensor (A/F sensor), which is applied to a 1997 model year LEV vehicle was developed. This sensor enables the detection of the exhaust gas air fuel ratio, both lean and rich of stoichiometric. This A/F sensor was developed from a lean mixture sensor, which has a proportional output to the exhaust gas air fuel ratio in the lean region only, by widening the detection range to rich air fuel ratios to 12:1. This sensor is comprised of a zirconia solid electrolyte and a platinum electrode with a ceramic coating used as a diffusion layer. As a result of improvements, it has a effective air fuel ratio range from 12 to 18 as required for LEV vehicles with model based air fuel control systems. It has a fast light off, -- within 20 seconds -- to minimize exhaust hydrocarbon content. Further, it has fast response times, less than 200 msec., to improve air fuel ratio controllability.

It is widely known that pellet-typed catalysts are deactivated by phosphorus (ZnDTP) that comes from engine oils. In this paper, the poisoning of monolithic three-way catalysts and oxygen sensors by engine oils is studied. First, catalysts and oxygen sensors were poisoned on the engine bench by test oils in which the quantity of phosphorus and ash was varied. Next, performance of the catalysts and sensors alone was examined and the vehicle exhaust emission at FTP mode was measured on a chassis dynamometer. The results indicate that phosphorus in engine oils poisons the monolithic catalyst and the oxygen sensor resulting in deterioration of the vehicle NOx exhaust emission. However, Ca sulfonate and Mg sulfonate detergents act by restraining phosphorus poisoning of the catalyst and the oxygen sensor. Through analysis of the catalyst and sensor surfaces, it is concluded that phosphorus poisons the catalyst and sensor forming a dense coating.