Search Results

This paper describes the conversion of a stationary spark ignition engine to a heavy duty (HD) natural gas engine suitable for transportation applications, in response to the new urban truck and bus legislation of 1994 and 1998. The approach to the fuel and ignition control system is to use a microprocessor controlled engine management system based on inputs from combustion air and natural gas mass flow sensors. As the emission control system is also based on stoichiometric three way catalyst technology, it is felt that the control approach is very robust. The engine and control system were first mounted on a HD dynamometer for the development work where engine control parameters were calibrated. In addition steady state emission data were collected and estimates of the HD transient emission levels were obtained.

The solenoid fuel injector's dynamic behavior has been modelled by digital simulation techniques. The results help to explain the injector's non-linear flow calibration at short control pulse widths. This behavior is reproduced in an experimental comparison, and recommendations are made for reducing these calibration non-linearities based on model predictions.

The new technology of hydraulic fluidics has been applied to the control of aircraft hydraulic systems in three areas: hydraulic circuit damage isolation, control column artificial feel computation, and the sequencing of landing gear motion. Successful development is demonstrated, and hydraulic fluidics are shown to produce considerable improvements to hardware in specific instances.