A device to reduce the loss of fresh charge and noise in the exhaust system of a two-stroke outboard motor

Installation of the resonator in a generally accepted form on two-stroke outboard motors is not possible due to such technical features of the motors as exhaust in deadwood, limitation of the length of the outboard motors for engines of different power due to the regulated height of the transom, a rotating vertical shaft in the exhaust gas outlet zone, the inability to change the configuration of the exhaust system due to a certain shape of the deadwood part having a certain design aimed at improving, primarily, hydrodynamic characteristics and, secondly, strength characteristics taking into account the cantilever arrangement of the motor. Based on the accumulated experience of the Scientific, Educational and Production Laboratory "Outboard Boat Motors" of the Department of Operation of Water Transport and Industrial Fisheries of the Astrakhan State Technical University in the field of reducing the environmental impact of small vessels with outboard boat motors, and taking into account their design features, a device is being developed capable of replacing the resonator according to its characteristics. The proposed device is capable of creating an air valve that can stop the flow of exhaust gases with a part of the fresh charge when their pressure decreases at the outlet of the exhaust window by the end of the exhaust process and returns them to the exhaust window. The fresh charge entering the engine cylinder through the intake window during the intake cycle is directed to the exhaust window under the action of purging, where it is delayed by the flow of exhaust gases created by back pressure. The device is also able to reduce the underwater noise of a small vessel due to the interference of sound waves, which is created by the reverse flow of exhaust gases towards the exhaust window. 

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