Method and apparatus for improving the gas flow in an internal combustion engine exhaust manifold
AssigneeSociete d'Etudes de Machines Thermiques S.E.M.T.
InventorRemi Curtil
Life of this patent
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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.
Claims26
A method for reducing the pressure oscillations in a stream of exhaust gases delivered to a supercharger turbine from a multiple-cylinder bank of an internal combustion engine, the method including connecting an exhaust port of each cylinder in the bank to the inlet end of a corresponding branch pipe, connecting the outlet end of each branch pipe into a single manifold pipe extending alongside the bank of cylinders, and connecting the downstream end of the manifold pipe to the inlet of a supercharger turbine, said connections to the branch pipes and the supercharger turbine constituting the only openings in said manifold pipe, wherein the improvement comprises:
- constricting the flow cross section of each branch pipe at a location adjacent to its outlet end relative to the flow cross section of the inlet end of said branch pipe by a ratio in the range from about 0.3 to about 0.8, the constriction being located closely adjacent to the inlet of the branch pipe so as to maintain the potential energy of the exhaust gases flowing in said branch pipe at a high level during the period from opening of the exhaust valve of the cylinder until the piston reaches bottom dead center and
- providing a substantially uniform flow section throughout the length of the manifold, the diameter of said uniform flow section being smaller than the diameter of each cylinder bore by a ratio in the range from about 0.30 to about 0.75, to provide a high flow velocity of the exhaust gases in the manifold, thereby exerting a strong ejector action on the exhaust gases from each cylinder at the entry from the outlet end of the corresponding branch pipe into the exhaust manifold.
Apparatus for reducing pressure oscillations in a stream of exhaust gases from an internal combustion engine, the engine having a plurality of cylinders arranged in each of at least one bank of cylinders, a piston in each cylinder, an exhaust port leading from each cylinder, an exhaust valve in each exhaust port, means for opening each exhaust valve during the expansion stroke of the corresponding piston and for closing the exhaust valve after the piston reaches bottom dead center, a single pipe exhaust manifold extending alongside the bank of cylinders, the manifold having an outlet end, a plurality of connecting pipes equal to the number of cylinders in said bank, each connecting pipe having an inlet end connected to the exhaust port of a corresponding cylinder and an outlet end connected to the manifold, said connections to the plurality of connecting pipes and to said supercharger turbine being the only openings for exhaust gas flow in said manifold pipe, and a supercharger turbine connected to the outlet end of the manifold, wherein the improvement comprises:
- the outlet end of each connecting pipe being located closely adjacent to its inlet end, and the ratio of the cross-sectional flow area at the outlet end of each connecting pipe to the flow area at the inlet end being in the range from about 0.3 to about 0.8, such that the potential energy of the exhaust gas in the connecting pipe is maintained at a high level during the period from opening of the exhaust valve until the piston reaches bottom dead center, and
- the manifold pipe having a substantially uniform flow area the diameter of which is less than the diameter of each cylinder bore by a ratio in the range from about 0.30 to about 0.75, such that a high velocity is maintained by the exhaust gases flowing in said manifold piper.
Dependencies are inferred from the claim text.