Abstract: A method wherein a number of cylinders (2, 3; 1, 4) are grouped on a same exhaust gas manifold (8, 10) such that the pressure in the exhaust pipe (1e . . . 4e) undergoes time-dependent fluctuations of substantial amplitudes, and the exhaust valve (6) of a cylinder (1) is opened during induction or filling thereof (i.e. adjacent to the bottom dead center) so that, in a given engine speed range, a phase (28) of low instantaneous exhaust pressure prevailing in the exhaust pipe enables the inlet pipe (1a)/cylinder (1)/exhaust pipe (1e) to be scavenged while the inlet valve (5) and the exhaust valve (6) are simultaneously open. The phase (29) of high instantaneous exhaust pressure, caused by another cylinder, after the inlet valve (5) has closed and while the exhaust valve (6) is still open, is used for post-charging the cylinder (1) with air (A) previously stored in the exhaust pipe (1e).

Abstract: The invention relates to a method and apparatus for arranging a post-charging two-stroke engine. The apparatus includes a post-charging system (16) including an air admission duct (22) to the cylinder (14). The duct communicates intermittently either with the source of scavenging air (A) or alternatively with a chamber (30) for storing gases under pressure. Advantageously, the chamber (30) is inside the piston (12), whereas the air admission duct (22) is formed by at least one curved duct going round the cylinder (14) and having sufficient volume to constitute a reserve of charging air for use in post-charging. The invention improves engine operation.

Abstract: A method of operating a four-stroke cycle Diesel engine supercharged by an exhaust gas-driven turbocompressor with valve timing comprising a partial overlap of the opening periods of the exhaust and intake valves, with early intake closure and partial exhaust closure for the major part of the intake step followed by partial reopening of the exhaust and its final closure near bottom dead center after closure of the intake valve. At low and medium engine powers part of the supercharged intake air is bypassed to an end of an exhaust manifold, thereby increasing the cylinder filling factor and combustion air excess and substantially reducing exhaust valve temperature in the mid-power operating range of the engine.

Abstract: The invention relates to a method and a device for improving the efficiency of a four-stroke-cycle internal combustion engine. The main purpose of the invention is to obtain an effective compression ratio that is capable of automatic variation without introducing additional elements whatever the load, but only by adapting the engine cycle timing diagram. Said timing diagram includes an overlap stage between the lifts of at least one exhaust valve and at least one intake valve, said intake valve being closed near or before the bottom dead center of the piston, and said exhaust valve being closed beyond the instant of fixed closing of the intake valve.

Abstract: An internal combustion engine supercharged with air by an exhaust gas-driven turbo-compressor discharging through a by-pass duct a tapped flow rate of compressed air into the exhaust gas pipe-line feeding the turbine, said tapped flow rate of compressed air being heated by means of a heat exchanger inserted into the by-pass duct and through which are flowing the exhaust gases from the turbine, said tapped flow rate of heated compressed air being injected into the upstream end of the exhaust manifold of the engine.

Abstract: This invention relates to a method and devices for improving the external cooling of an exhaust valve of internal combustion engines. This method consists in extending the open period of the exhaust valve beyond the normal closing instant by preventing it from closing completely at that instant but by reducing the free flow section between the valve and its seat to a residual value which is substantially constant and small compared to the maximum flow section corresponding to the full opening of the valve. Said devices comprise means for obtaining such residual opening of the exhaust valve.

Abstract: Method and exhaust manifold for damping the pressure oscillations in an exhaust manifold of an internal combustion engine, consisting in throttling the gas flow in the vicinity of the cylinder outlet and then in accelerating the gases flowing in the manifold by providing a uniform flow section in the manifold substantially smaller than that of the cylinder bore.

Abstract: A method for improving the efficiency of an internal combustion engine such as a Diesel engine, by ensuring, on the one hand, efficient cylinder scavenging, particularly at light engine loads and/or low speeds, and on the other hand, a reduction of the effective compression ratio resulting in temperature reduction preferably under high engine loads and/or at high speeds. Said method consists in creating, for each engine cylinder and each engine cycle, a reserve of compressed air, during the intake stage, with the intake air and in compressing it by retarding the closing of the intake valve. A non-return valve is accommodated in the intake conduit and said gas reserve is contained in the space between the intake valve and the non-return valve.

Abstract: The intake ports of the combustion chambers of two alternately-operating cylinders of a two-stroke internal combustion engine are connected by a conduit which sets up temporary communication between the two cylinders. In operation, while the piston of one cylinder is at the top dead center, explosive mixture is sucked via an opening in the skirt of the piston and through said conduit to scavenge the other cylinder. During the driving stroke of the first cylinder, just before opening of the exhaust, its piston uncovers the intake port so that the residual energy of the combustion gases supercharges the explosive mixture in the other combustion chamber.

Abstract: Two cylinders of a Diesel or gasoline engine are connected by a pipe leading into ports of the combustion chambers which are simultaneously uncovered by the respective pistons at the beginning of the exhaust phase of one chamber and the end of the intake phase of the other. During this temporary communication, the residual energy of the exhaust gases in said one chamber compels air in said tube to supercharge said other chamber. Passageways are provided in the pistons which connect said pipe with air inlet and exhaust manifolds to ensure scavenging of the pipe between the supercharging periods.