An understanding of exhaust processes, especially during
unsteady engine operation, greatly assists in achieving emission
goals. Conventional~i.e., integral~measurement systems only provide
lump-sum, final values at the end of a given interval, or
instantaneous rate values during steady-state operation.
The paper presents a system for measuring instantaneous emission
values during unsteady engine operation. The system is designed for
installation in commercial vehicles, it is resistant to vibration,
and it does not affect fuel consumption.
The equipment includes infrared CO analyzers with transistorized
sensors, rather than gas-filled receptor chambers which are
sensitive to vibration. Mass flow rates of inlet combustion air
rather than exhaust are measured, due to temperature fluctuations
of exhaust. The produced electric signals are amplified, corrected,
and filtered before they are processed to provide read-out emission
values. Measuring deficiencies which tend to delay and reduce peak
values can be overcome by the incorporation of
proportional-differential electronic circuits.