Patent ID: 7559314

Claim:
A method in a internal combustion engine for controlling a unit injector type fuel injector, the fuel injector comprising a plunger which is driven by a rotating camshaft and which during a working stroke generates a hydraulic pressure increase in the fuel, the method comprising: regulating hydraulic pressure increase in the fuel with regard to pressure build-up with a spill valve; regulating an injection sequence with a needle control valve; regulating the spill valve and the needle control valve such that additional plunger retardation force is produced in a part of a working stroke in addition to a normal retardation force that is produced by a plunger return spring and flow resistance in the injector; and using a camshaft to extend a crankshaft angle interval for injection with a required plunger speed beyond the crankshaft angle interval used in a normal injector without additional plunger retardation force.