In Russia, a method for operating a two-stroke engine with a supercharger has been patented, which allows utilizing the energy of exhaust gases without impairing cylinder scavenging. The solution involves changing the exhaust scheme and redistributing flows in the exhaust system; the development is being carried out by the St. Petersburg company "Northern Wind."
According to the new scheme, after the power stroke, the combustion products exit through the exhaust port into the manifold. Then, the cylinder is scavenged with a fresh charge through the scavenging ports. At a specific moment, the exhaust manifold is blocked by a special device, increasing pressure and returning part of the fresh mixture back into the cylinder.
The key difference is the use of a channel through which part of the exhaust gases is directed to the gas turbine. Before the manifold is blocked, residual gases that have not escaped into the atmosphere enter the turbine. After blocking, part of the flow that has not returned to the cylinder is directed there.
This scheme allows simultaneously maintaining effective cylinder cleaning and utilizing exhaust energy. The obtained energy can be used in a separate expansion machine or to drive a compressor.
The authors indicate that the solution reduces the thermal load on the engine and increases its specific parameters. Additionally, it is permissible to regulate the proportion of gases entering the turbine, depending on the operating mode.