puristusyönteisen

Puristusyönteisen is a Finnish term that translates to "compression ignition" or "compression-start." It refers to a type of internal combustion engine where the fuel is ignited solely by the heat generated from the compression of air within the cylinder. This is in contrast to spark-ignition engines, like gasoline engines, which use a spark plug to initiate combustion.

The process in a puristusyönteisen engine begins with the intake stroke, where only air is drawn into the cylinder. During the compression stroke, this air is compressed to a very high pressure, causing its temperature to rise significantly. As the piston nears the top of its stroke, fuel is injected into the extremely hot, compressed air. The high temperature causes the fuel to auto-ignite, leading to the power stroke and the subsequent expulsion of exhaust gases.

This method of ignition is characteristic of diesel engines. The high compression ratios required for auto-ignition mean that puristusyönteisen engines are typically more robust and heavier than gasoline engines. They are also known for their high torque and fuel efficiency, making them suitable for heavy-duty applications such as trucks, buses, and industrial machinery. The absence of a spark plug simplifies the ignition system but requires precise fuel injection timing and a fuel that can readily auto-ignite.