Device for controlling air compressed in a cylinder of an internal combustion engine by means of a decompression valve

The control device uses a decompression valve (3) moved into an open or closed position, via an operating piston, during the compression stroke of the reciprocating piston used to compress the air within the engine cylinder. The pressure required to open the decompression valve (3) is provided by a high pressure fuel pump (16), with the air extracted from the cylinder fed to an exhaust gas line (4) or a pressurised air reservoir (10), the pressurised air feed to which is selectively controlled via a solenoid (14) which is controlled by an electronic control unit (15) e.g. of the engine electronics. Pref. the decompression valve is incorporated in the cylinder head in addition to the gas exchange valves