Multi-fuel engine system
View Patent ↗Various methods and systems are provided for an engine capable of receiving liquid and gaseous fuel. In one example, cylinder misfire may be identified based on a misfire monitor. The misfire monitor may detect misfire based on signals from a crankshaft sensor.
1. A system comprising:
an engine having a plurality of cylinders with pistons coupled to a crankshaft;
a crankshaft speed sensor; and
a controller having a processor and a memory holding non-transitory computer readable storage media, the controller configured to:
measure a half-order torsional vibration of the engine based on signals from the crankshaft speed sensor;
determine an amplitude of the half-order torsional vibration;
when the amplitude is greater than a threshold amplitude, indicate misfire in at least one of the plurality of cylinders;
responsive to misfire being indicated: determine which cylinder of the plurality of cylinders is misfiring based on a phase of the half-order torsional vibration; and increase a fuel injection amount to the misfiring cylinder;
determine a coefficient of variation (COV) of the plurality of cylinders based on the measured half-order torsional vibration; and
adjust fueling duration to one or more of the plurality of cylinders based on the COV.
2. The system of claim 1 , wherein the engine is configured to operate with at least a first fuel and a second fuel, and wherein to increase the fuel injection amount to the misfiring cylinder, the controller is configured to increase a fuel injection amount of the first fuel relative to the second fuel.
3. The system of claim 2 , wherein the first fuel is a liquid fuel and the second fuel is a gaseous fuel.
4. The system of claim 3 , wherein the controller is further configured to determine, for each cylinder of the plurality of cylinders, a misfire limit for each operating point of a plurality of operating points based on the amplitude of the half-order torsional vibration measured across the plurality of operating points.
5. The system of claim 4 , wherein the misfire limit for a given cylinder of the plurality of cylinders includes a minimum open duration for a liquid fuel injector coupled to the given cylinder.
6. The system of claim 5 , wherein the controller is further configured to operate each cylinder of the plurality of cylinders at a respective predetermined ratio of gaseous fuel to liquid fuel, each predetermined ratio including a maximum amount of gaseous fuel to deliver requested engine output while remaining above a respective misfire limit.
7. A method comprising, with a controller having a processor and a memory holding non-transitory computer readable storage media:
measuring a half-order torsional vibration of an engine based on signals from a crankshaft speed sensor, the engine having a plurality of cylinders with pistons coupled to a crankshaft;
determining an amplitude of the half-order torsional vibration;
when the amplitude is greater than a threshold amplitude, indicating misfire in at least one of the plurality of cylinders;
responsive to misfire being indicated: determining which cylinder of the plurality of cylinders is misfiring based on a phase of the half-order torsional vibration; and increasing a fuel injection amount to the misfiring cylinder;
determining a coefficient of variation (COV) of the plurality of cylinders based on the measured half-order torsional vibration; and
adjusting fueling duration to one or more of the plurality of cylinders based on the COV.