For the vehicles with frequent stop-start operations, fuel
consumption can be reduced significantly by implementing stop-start
operation. As one way to realize this goal, the pneumatic hybrid
technology converts kinetic energy to pneumatic energy by
compressing air into air tanks installed on the vehicle. The
compressed air can then be reused to drive an air starter to
realize a regenerative stop-start function. Furthermore, the
pneumatic hybrid can eliminate turbo-lag by injecting compressed
air into manifold and a correspondingly larger amount of fuel into
the cylinder to build-up full-load torque almost immediately.
This paper takes the pneumatic hybrid engine as the research
object, focusing on evaluating the improvement of fuel economy of
multiple air tanks in different test cycles. Also theoretical
analysis the benefits of extra boost on reducing turbo-lag to
achieve better performance.
A six-cylinder pneumatic hybrid diesel engine model is built in
the MATLAB/Simulink environment with Stateflow®. Based on this
model, a pneumatic hybrid vehicle driving cycle simulation program
has been applied to analyze the charging and discharging processes
during various bus duty cycles. The analysis shows that the
pneumatic hybrid engine can reduce fuel consumption by at least 5%
by realizing stop-start operation, and eliminate 90% of the idling
time. A new engine concept and structure which can realize the
boost engine function has been proposed. The theoretical analysis
of this engine is also given out.