Abstract
The previous model is equipped with FC stack assembly under the floor of the car, but the new model is equipped consolidated FC units in the engine compartment. It results in great mountability equivalent to that of conventional engine. In order to achieve equipping FC stack in the engine compartment, it is necessary to enhance G resistance and miniaturize FC stack at the same time. In order to secure reliability of high voltage safety and hydrogen safety, it is necessary to control cell seal leakage caused by cell deviation. We adopted external constraint structure, in addition to the friction constraint force between each cell, to control quantity of cell deviation in less than quota. As the external constraint structure, we installed silicon rubber called Filling in the gap of FC cell stack and stack case. It results in enhancement of G resistance by 1.6 times compared to the previous model. Optimizing the rigidity of stack case and the gap size between cell stack and stack case is necessary to control external constraint force using Filling. The new stack case is made by FSW (Friction Stir Welding) line joining of upper and lower case, which are made by casting respectively. This case structure achieves the requirement written above and miniaturize stack at the same time. In the FC stack manufacturing process, the stacking process of 330 cells was automized. It realized stacking cells with high dimensional accuracy at the shorter cycle time. It results in reduction of cell deviation and contribution to control the gap between cell stack and stack case, and control external constraint force.
