Puristussytytysjärjestelmät

Puristussytytysjärjestelmät, often translated as compression ignition systems, refer to the method by which internal combustion engines ignite their fuel-air mixture. Unlike spark ignition engines which rely on an external spark plug to initiate combustion, puristussytytysjärjestelmät utilize the heat generated by compressing the air within the cylinder to a very high temperature. When fuel is then injected into this superheated air, it spontaneously ignites and burns, driving the piston.

This principle is the foundation of diesel engines. The high compression ratio in diesel engines is crucial for achieving the necessary temperatures for auto-ignition. The fuel is typically injected directly into the combustion chamber in a finely atomized spray just before the piston reaches the top of its compression stroke. The timing and quantity of fuel injection are precisely controlled to manage the combustion process and engine output.

Advantages of puristussytytysjärjestelmät include their generally higher thermal efficiency compared to spark ignition engines, leading to better fuel economy. They also tend to produce more torque at lower engine speeds, making them suitable for heavy-duty applications like trucks, buses, and industrial machinery. However, diesel engines historically have been associated with higher emissions of particulate matter and nitrogen oxides, although modern advancements in emission control technology have significantly mitigated these issues. The noise and vibration levels can also be higher than in gasoline engines due to the more forceful combustion process.