5. Electronic control system hardware
designs
The hydrogen fueled engine was modified from a JH6OO
a single-cylinder gasoline engine produced by Jialing
company. The cylinder diameter journey is 94 85 mm,
and the combustion chamber was half ball, and the
compression ratio is 9.7. Maximum output power/engine
speed was 30 KW/6000 rpm. Hydrogen fuel of purity 99% was
supplied by a hydrogen gas bottle with output pressure
15 MPa. After output pressure of the hydrogen gas was lessened
to 0.2e0.5 Mpa. The hydrogen gas was periodically
driven into intake manifold. The amount of hydrogen injection
and injection timing were decided by ECU in accordance
with the engine operation conditions.
Electronic control system of a hydrogen-fueled engine
includes three parts which are sensors, ECU, actuator. Fig. 5
gives the box-diagram of hardware of control system. Ignition,
and water injection rate of intake manifold, can be
adjusted and controlled by the ECU to ensure the optimum
ignition.
5.1. Backfire detection circuit of intake manifold
With uncertainty of occurrence of backfire of hydrogen
engine, a high sensitivity circuit for backfire of detection was
designed to detect rapidly occurrence of backfire as shown in
Fig. 6. And there are main features on the circuit as
follows:(1)A bandoning the traditional thinking of the
pressure sensor detection,therefore avoiding the lag and
error of sensors detection (may be other reasons caused by
pressure fluctuation); (2)combining physical principles
with circuit design that can be rapid and reliable to detect the
occurrence of backfire;(3)circuit design is clear and simple,
software programming is easy to implement.
The working principle of the circuit for detection of backfire
is that: because backfire is caused by the ignition of
mixture in intake manifold, and the mixture is ignited by the
hot spot of intake valve or flame entering to intake manifold
from the intake valve. So detection probe (well-heat-