Studies on ignition methods for hydrogen engines with injection right before TDC.

This study is for establishing the spark ignition method for injected high pressure hydrogen to replace the hot surface ignition because the spark ignition saves electrical power, improves durability and prevents abnormal combustion. The experiments were conducted both in a constant volume combustion chamber with Schlieren method and in an actual piston engine in order to optimize the spark gap position and timing which could realize stable ignition with a short delay. Ignition for an actual engine took place in a much larger region than for a constant volume chamber due to high pressure, high temperature and gas flow, although a constant volume chamber can be used for understanding the fundamentals. As the optimized spark ignition method, the following was learned from the actual engine experiments; full-transistor spark generation at 3 to 5 mm from an injection hole and almost simultaneous fuel injection with the spark.