Patent ID: 7798130

Claim:
An internal combustion engine comprising: a variable volume combustion chamber; an air intake system for delivering charge air to the combustion chamber; an exhaust system for relaying combusted gas from the combustion chamber to atmosphere; and a fuel injection system for delivering fuel into the charge air for combustion therewith in the combustion chamber; wherein the fuel injection system comprises: a fuel injector which functions as a positive displacement pump and dispenses an amount of fuel which is fixed for each and every operation of the injector; and a controller which controls the operation of the fuel injector; wherein: in each of at least a majority of engine cycles the fuel injector is operated on a plurality of occasions by the controller; in response to an increasing engine speed and/or load the controller increases in amount the fuel delivered per engine cycle by increasing in number the occasions the fuel injector is operated per engine cycle; in response to a decreasing engine speed and/or load the controller reduces in amount the fuel delivered per engine cycle by reducing in number the occasions the fuel injector is operated per engine cycle; and the fuel injector comprises: a housing in which a fuel chamber is formed; an electrical coil; and a piston which slides axially in a bore in the housing under the action of the electrical coil the piston sliding between two end stops which ensure that the piston has a set distance of travel in each operation.