Method and device for improving the efficiency of internal combustion engines
AssigneeSociete d'Etudes de Machines Thermiques S.E.M.T.
InventorRemi Curtil
Life of this patent
Estimating the term…
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.
Claims12
A method for improving the efficiency of a four-stroke cycle internal combustion engine having an intake manifold, at least one cylinder, and for each cylinder a piston, an exhaust valve, an intake valve, and an intake passageway between the intake manifold and the intake valve, the method comprising for each engine cycle in each cylinder:
- opening the intake valve before the piston reaches top dead center at the end of the exhaust stroke and shutting the exhaust valve after top dead center during the intake stroke to define a period when both valves are open simultaneously;
- retarding the shutting of the intake valve until after the start of the compression stroke;
- selectively blocking the intake passageway at a location spaced from the intake valve to permit one-way flow of gas from the intake manifold through the intake passageway past said location but to prevent, at least for light engine loads, reverse flow through the intake passageway past said location to the intake manifold, said blocking location being selected to create a reserve chamber of predetermined volume in the intake passageway between the intake valve and said location, a reserve of gas being compressed in said chamber while the intake valve is open during the compression stroke and then being expanded through the intake and exhaust valves during the next period of simultaneous opening thereof to provide improved scavenging of the cylinder at the start of each intake stroke;
- and
- opening a path between the intake valve and the intake manifold at high engine loads for permitting the escape of at least part of said compressed gas reserve back into said manifold, thereby reducing the effective compression ratio at high load.
Apparatus for improving the efficiency of a four-stroke cycle internal combustion engine having an intake manifold, a plurality of cylinders, a crankshaft, and, for each cylinder, a piston connected to the crankshaft, an exhaust valve, an intake valve, an intake conduit connecting the intake manifold to the intake valve, means for opening the exhaust valve for a predetermined angle of rotation of the crankshaft during each engine cycle, and means for opening the intake valve for a predetermined angle of rotation of the crankshaft during each engine cycle, wherein the improvement comprises:
- non-return valve means mounted in said intake conduit at a location spaced from the intake valve to provide a reserve chamber of predetermined volume in the conduit, said nonreturn valve permitting flow from the intake manifold therethrough but preventing flow in the reverse direction;
- said means for opening the exhaust valve being adjusted to open said exhaust valve during the exhaust stroke and to shut said exhaust valve after the piston reaches top dead center at the end of the exhaust stroke;
- said means for opening the intake valve being adjusted to open said intake valve before the piston reaches top dead center during the exhaust stroke and to shut said intake valve during the compression stroke to form a reserve of compressed gas in said reserve chamber during the beginning of each compression stroke prior to the shutting of the intake valve, so that said reserve is released into the cylinder upon the subsequent opening of the intake valve to provide effective scavenging during the period when both the intake and exhaust valves are open simultaneously;
- a bypass path around said non-return valve means connecting said intake valve to said intake manifold;
- bypass valve means in said bypass path;
- and means for selectively opening said bypass valve means at high engine loads to release at least part of said reserve of compressed gas for reducing the effective compression ratio of the cylinder at high engine loads.
Dependencies are inferred from the claim text.