Control system for a gaseous fuel internal combustion engine utilizing PID gain scheduling parameters

摘要

A fuel control system is provided for use with an internal combustion engine having at least one cylinder, a source of gaseous fuel and an intake passageway for fluidly connecting the air intake to the combustion cylinder. The control system includes a gas flow rate sensor which generates an output signal representative of the fuel flow rate to the engine as well as a mass air flow sensor which generates a signal representative of the mass air flow rate to the engine. A fuel valve is fluidly connected in series between the source of gaseous fuel and the air intake passageway. The fuel valve is actuated by an electrical pulse stream between an open and a closed position so that the duty cycle of the pulse stream is proportional to the amount of fuel supplied to the engine. In response to the fuel flow rate signal, the air flow rate signal and a target air/fuel ratio, the control system generates PID gain scheduling parameters relative to the duty cycle of the pulse stream. The system then varies the duty cycle of the pulse stream as a function of the PID gain scheduling parameters to obtain the target air/fuel ratio. Optionally, an air/fuel sensor generates an output signal representative of the actual air/fuel ratio supplied to the engine. This signal is compared to the target air/fuel ratio and utilized to generate second PID gain scheduling parameters to further modify the duty cycle of the pulse stream in order to obtain the target air/fuel ratio.