Fig. 1 shows the intake manifold pressure and cylinder pressure
curve in a HICE [1], which is water-cooled, horizontal
type, its displacement is 482cc, bore is 85 mm, stroke is 85 mm,
compression ratio can be changed from 4.8 to7.93. at the speed
of 2100 rpm when backfire happens. From Fig. 1,we can find
that ignition in the mixture of combustion chamber started in
point A, then, fresh mixture of intake manifold was also
ignited so that low intake manifold pressure in point B
suddenly increased with volatility.
It can be seen from Fig. 2 that after pre-ignition occurred,
the mixture pressure increased too quickly, and pre-ignition
became more and more serious with the hydrogen internal
combustion engine carrying out the work of the cycle, that is,
the ignition continued to advance, and the maximum pressure
continuously reduced, and the crank angle corresponding
to highest temperature in the initial stage of cylinder
compression step by step moved forward, and the temperature
of mixture in the initial stage of cylinder compression
step became higher and higher so that the higher and higher
temperature of mixture would benefited to ignite the fresh
charge by the high temperature exhaust gas or incandescent
spot in cylinder after intake valve opened, and backfire