Tihendussuhtele

Tihendussuhtele, or compression ratio in English, is a fundamental parameter in internal combustion engines. It is defined as the ratio of the volume of the cylinder and combustion chamber when the piston is at the bottom dead center (BDC) to the volume when the piston is at the top dead center (TDC). Mathematically, it is expressed as V_d / V_c, where V_d is the displaced volume and V_c is the clearance volume.

A higher compression ratio generally leads to a more efficient engine because it allows for greater expansion of the burning fuel-air mixture, extracting more energy. This often results in improved fuel economy and increased power output. However, higher compression ratios also increase the likelihood of engine knocking or detonation, a phenomenon where the fuel-air mixture ignites prematurely and uncontrollably, which can damage the engine.

Automotive engines typically have compression ratios ranging from 8:1 to 12:1 for gasoline engines, and higher for diesel engines, often exceeding 15:1. Diesel engines can tolerate higher compression ratios because they rely on compression ignition, where the heat generated by high compression ignites the fuel, rather than a spark plug. The specific compression ratio chosen for an engine design is a compromise between efficiency, power, emissions, and durability. Modern engine management systems and advanced fuel technologies help to mitigate the risks associated with high compression ratios.