Patent ID: 8805607

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 which comprises: a housing in which a pumping chamber is formed; an electrical coil; a piston which slides axially in a bore in the housing under action of the electrical coil; and a biasing spring which acts on the piston; 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; motion of the piston in a first direction draws fuel into the pumping chamber and motion of the piston in the opposite direction expels fluid from the pumping chamber; motion of the piston under action of the spring occasions a voltage in the coil; the controller uses the voltage occasioned by the piston motion under action of the spring to determine an indication of an amount of fuel vapour present in the pumping chamber; and the controller adjusts operation of the injector in dependence on the indicated amount of fuel vapour, the controller increasing in number the occasions the fuel injector is operated per engine cycle in response to an indication of an increased fuel vapour amount.