Otto-cycle internal combustion engine

Abstract

An Otto cycle internal combustion engine () provided with a combustion chamber () and an inlet () and an outlet () with respective valves (and), and a suction passage () leading to the said at least one inlet () to conduct the flow of fluid material thereto. The engine () further comprises a control valve () arranged upstream of the inlet valve () and being operable to change between a condition in which it opens the suction passage () and a condition in which it closes the suction passage (). An engine operating position sensor () provides signals indicative of the operating position of the engine (). There is also an engine power control (). A variable intermediate position control signal generator (), generates control signals at times respectively between the beginning and the end of each of a succession of inlet valve opening periods of the engine cycle. It is connected to receive signals from the engine operating position sensor () and the engine power control () and to send the control signals to the control valve () in such a manner that in between an opening of the inlet valve () and the immediately following closure thereof there is a period in which the suction passage () is open and a period in which it is closed, the period for which it is open being in dependence upon the engine power control () output. The invention extends to a method of operating such an engine ().