Patent ID: 8849546

Claim:
A method of selecting between two operation modes in a dual fuel internal combustion engine of the diesel-type, comprising a combustion chamber being at least partly delimited by a piston, a first fuel supply for a first fuel, the first fuel supply being located at least one of in and at at least one of the combustion chamber and an inlet port of the combustion chamber, and a second fuel supply for a second fuel, the engine having two different operation modes, both operation modes comprising the steps of: pre-mixing the first fuel in the at least one of the combustion chamber and the inlet port, compressing the charge containing the first fuel to conditions that allow auto ignition or the second fuel, performing a first injection of the second fuel into the combustion chamber to initiate auto-ignition of the second fuel, thereby initiating conditions for combustion of the fuel remaining in the combustion chamber after auto-ignition of the second fuel, wherein the first operation mode is distinguished by homogenous ignition and combustion of the remaining fuel, the second operation mode is distinguished by pre-mixed flame propagation combustion of the remaining fuel, the method further comprising the step of: adjusting the amount of the second fuel injected in the first injection of the second fuel, and/or the timing of said the first injection of the second fuel, so as to control the combustion chamber temperature and pressure after auto-ignition of the second fuel such that selection between the first and second operation modes is achieved, wherein the second operation mode comprises: performing the first injection of the second fuel into the combustion chamber to initiate auto-ignition of the second fuel for igniting the first fuel, thereby initiating conditions for pre-mixed flame propagation combustion of the first fuel, and performing at least one subsequent injection, the subsequent injection supplying additional kinetic energy into the combustion process to thereby enhance turbulence intensity and propagation speed of the flame.