Dual fuel common rail depressurization during engine shutdown and machine using same

摘要

A machine includes a compression ignition engine 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. When an engine shutdown command is communicated to an electronic controller, the supply of gaseous fuel to the gas rail is stopped and the gaseous fuel common rail is depressurized by continuing to run the engine and inject gaseous and liquid fuels while commanding a liquid pressure greater than the gas pressure. After the gas rail pressure has achieved an acceptable shutdown pressure, the engine is stopped. The gas rail pressure is then reduced to atmospheric pressure followed by the liquid fuel common rail being reduced to atmosphere pressure after stopping the engine.

主权项

1. An engine comprising:
an engine housing that defines a plurality of cylinders; a piston positioned to reciprocate in each cylinder of the plurality of cylinders to define a compression ratio greater than 14:1; a plurality of fuel injectors, each fuel injector of the plurality of fuel injectors including a gaseous nozzle outlet set and a liquid nozzle outlet set positioned for direct injection into a corresponding cylinder of the plurality of cylinders; a gaseous fuel common rail and a liquid fuel common rail fluidly connected to a first fuel inlet and a second fuel inlet, respectively, of each fuel injector; and an electronic controller operatively coupled to each fuel injector, the electronic controller being configured to receive a signal indicative of a gaseous fuel pressure within the gaseous fuel common rail, receive an engine shutdown command signal, and close a gaseous fuel shutdown valve in response to the engine shutdown command signal, the gaseous fuel shutdown valve being disposed upstream of the plurality of fuel injectors, and continue running the engine after the engine shutdown command signal according to an engine shutdown algorithm, the engine shutdown algorithm including
maintaining a liquid fuel pressure in the liquid fuel common rail greater than the gaseous fuel pressure in the gaseous fuel common rail,injecting gaseous fuel into at least one cylinder of the plurality of cylinders to reduce the gaseous fuel pressure in the gaseous fuel common rail to below a threshold shutdown pressure, andstopping the engine after the gaseous fuel pressure is reduced below the threshold shutdown pressure.