Mitigation of intermittent cylinder misfire on dual fuel engines

A method of operating a dual fuel engine, the method comprising:

• supplying a liquid fuel into a cylinder of the dual fuel engine;
• supplying a gaseous fuel into the cylinder of the dual fuel engine;
• sensing a cylinder pressure with at least one pressure sensor operably coupled to the cylinder;
• sensing an output speed of the dual-fuel engine with an engine speed sensor;
• transmitting a cylinder pressure signal, engine speed signal, engine load signal, and timing signal to an electronic controller configured to analyze the cylinder pressure signal and engine speed signal;
• determining whether the cylinder is above a pre-determined pressure range and the cylinder is operating in a misfire condition based on the cylinder pressure signal;
• determining whether the dual-fuel engine is operating in a motoring condition based on the output speed, engine load, and crank shaft position, wherein the motoring condition is when a machine which is propelled by the dual fuel engine is propelled down a grade by gravity;
• transmitting a control signal from the electronic controller commanding to increase injection of a supply of liquid fuel to the cylinder when the electronic controller determines that the cylinder pressure is above the pre-determined pressure range and the cylinder is operating in the abnormal operating condition during a determined motoring condition;
• and
• purging an amount of an backflow gas from the cylinder and a fuel injector nozzle during the determined motoring condition with the increased supply of liquid fuel to lower the cylinder pressure within the pre-determined pressure range.

A machine, comprising:

• a frame;
• a dual fuel engine mounted on the frame, the dual fuel engine including a plurality of cylinders configured to combust a liquid fuel and a gaseous fuel;
• a liquid fuel source in communication with each of the plurality of cylinders and configured to supply the liquid fuel to each cylinder of the plurality of cylinders;
• a gaseous fuel source in communication with each of the plurality of cylinders and configured to supply the gaseous fuel to each cylinder of the plurality of cylinders;
• a pressure sensor operably coupled to each cylinder of the plurality of cylinders and configured to monitor and measure a cylinder pressure and transmit a cylinder pressure signal;
• an engine speed sensor configured to monitor an output speed of the dual-fuel engine and transmit an engine speed signal;
• and
• an electronic controller communicably coupled with the liquid fuel source, the gaseous fuel source, the pressure sensor, and the engine speed sensor, the electronic controller configured to receive the cylinder pressure signal from the pressure sensor of each cylinder of the plurality of cylinders, determine whether the cylinder pressure is above a pre-determined pressure range and at least one cylinder of the plurality of cylinders is operating in a misfire condition based on the received cylinder pressure signal, receive the engine speed signal from the engine speed sensor, determine whether the engine speed is below a pre-determined threshold and the dual-fuel engine is in a motoring condition based on the received engine speed signal wherein the motoring condition is when the machine which is propelled by the dual fuel engine is propelled down a grade by gravity, and when the electronic controller determines that the cylinder pressure is above the pre-determined pressure range and a particular cylinder of the plurality of cylinders is operating in the misfire condition during a determined motoring condition the electronic controller sends a control signal to increase an injection of the liquid fuel supply into the particular cylinder of the plurality of cylinders to purge an amount of backflow gas from the cylinder and a fuel injector nozzle during the determined motoring condition to lower the cylinder pressure within the pre-determined pressure range.