Dual fuel common rail transient pressure control and engine using same

摘要

A compression ignition engine is fueled from common rail fuel injectors that predominately inject natural gas fuel that is compression ignited with a small pilot injection of liquid diesel fuel. Before and after a rapid load loss transient, the liquid and gaseous rail pressures are controlled toward respective pressures based upon engine speed and load. During the transient, the liquid rail pressure is controlled relative to the gas rail pressure in order to maintain the liquid rail pressure greater than the gas pressure during the transient to avoid migration gaseous fuel into the liquid fuel side of the system.

主权项

1. A method of operating an engine comprising the steps of:
injecting gaseous fuel and liquid fuel directly into an engine cylinder from a gaseous nozzle outlet set and a liquid nozzle outlet set, respectively, of a fuel injector; compression igniting the injected liquid fuel to ignite the gaseous fuel; inhibiting migration of gaseous fuel into liquid fuel within the fuel injector by maintaining a liquid rail pressure greater than a gas rail pressure; the inhibiting step includes executing a first rail pressure control algorithm before and after a transient, and executing a second rail pressure control algorithm during the transient; initiating the transient by changing from a high fuel demand state of a first speed and load to a low fuel demand state of a second speed and load.