The surprising engine patent that we just learned about Kawasakiand its innovative 2-stroke engine with turbo and valves, is shaking up the two-wheel industry from north to south. What does it mean to re-market a two-stroke engine for road use? Be careful, because it is not something new, they have been working on it for some time and it seems that they are taking it seriously.
A 2-stroke engine is not characterised by the number or presence of valves, the type of lubrication or any other mechanical characteristic, such as pre-compression in the crankcase. The real difference between a 2-stroke engine and a 4-stroke engine lies in the number of revolutions of the crankshaft required to complete a full cycle.
In a reciprocating piston engine, this refers to how often the piston reaches its top dead center (TDC) before ignition and combustion occur. In a two-stroke engine, a single revolution of the crankshaft and a complete piston cycle from top dead center to bottom dead center (BDC) is required.
During the single revolution, the engine must draw in a fresh mixture, compress it, ignite it and expel the exhaust gases. Some of these processes therefore occur simultaneously, for example, the cylinder contains exhaust gases and fresh mixture at the same time. This simultaneity has been a disadvantage of 2-stroke engines, due to high losses, where the fresh mixture is expelled without being burned.
This is the revolutionary 2-stroke engine that Kawasaki has patented
This is where it comes in Kawasaki with the innovation of its patent. Kawasaki The turbocharger seeks to take advantage of the benefits of two-stroke engines without the losses. They use intake valves driven by a camshaft, supercharging of the intake air and direct injection. The latter avoids large losses, since the turbo or compressor only pushes air through the intake valves. The supercharger acts as a pre-compression and helps to expel the exhaust gases from the cylinder.
During the compression cycle, the piston further compresses the pre-compressed air, shortly before TDC, Kawasaki The fuel is injected directly into the combustion chamber and then ignited conventionally with a spark plug. On the way down to the BDC, the exhaust gases expand and are expelled, repeating the cycle. This means that there is one ignition for every revolution of the crankshaft. In addition, a planned spontaneous combustion can occur after direct injection, similar to a diesel engine, which enables efficient and fuel-efficient operation.
The advantages of the two-stroke engine are clear. One ignition per revolution results in smooth operation and continuous torque. Depending on how Kawasaki manage the exchange of gases in its new design, the valve train could be reduced to just one intake valve. The brand’s final purpose with this new engine is still unclear.
