Abstract: A two-stroke engine with controlled pneumatic injection is disclosed, wherein at least one connecting duct joins the combustion chamber of a first cylinder to the crankcase-pump of a second cylinder. The means for controlling the injection of carburetted air into the chamber of the first cylinder comprise at least one flange fixed rigidly to the shaft of the crankcase of the engine inside the crankcase-pump of the second cylinder. The flange comprises a recess on its peripheral portion so as to be able to isolate the crankcase-pump from or place it in communication with the inner volume of the combustion chamber at given times of the engine cycle.

Abstract: A device (4, 5) for introducing, under pressure, a fuel-air mixture into a first cylinder of an internal combustion engine, with the engine comprising at least one other cylinder having a pump crankcase. A connecting passageway (9) is provided between the pump crankcase (12) and the upper part of first cylinder (1), with the passageway being supplied with fuel. A communication between the passageway and the combustion chamber of the first cylinder is blocked, and a non-zero angular offset exists between the cycles of the cylinders. The device (4, 5) controls the start of injection by interrupting, in an intermittent and predetermined fashion, the communication between the passageway (9) and the pump crankcase.

Abstract: A method and device for introducing a carburetted mixture into a first cylinder of an internal combustion engine under pressure, this engine comprising at least one other cylinder with a pump crankcase, further comprising a connecting duct between the crankcase and the first cylinder, with an angular non zero shift between the cycle of each of the cylinders, and at least one of the gas transfer ports of said other cylinder is positioned so that a back-flow occurs therein during a part of the cycle.

Abstract: A device, and method for introducing a carburetted mixture under pressure into a chamber of a first cylinder of a two stroke-internal combustion engine. The device includes a feed valve cooperating with a seat for closing a duct feeding carburetted mixture into the chamber of a first cylinder, a valve returning arrangement and an assistance member comprising a separation element cooperating with one end of a stem of the valve. The assistance member separates a first volume and a second volume within each of which a pressure prevails, with the separation element having a movement and causing displacement of the valve under the action of the pressure difference between the pressure of the first volume and the pressure of the second volume.