Knacksensorer

Knacksensorer, often translated as "knock sensors," are electronic devices used in internal combustion engines to detect and prevent engine knocking or detonation. Engine knocking is an undesirable phenomenon where the fuel-air mixture in a cylinder ignites prematurely and uncontrollably, leading to a sharp, metallic pinging sound. This uncontrolled combustion can cause severe damage to engine components.

A knock sensor typically works by sensing the vibrations produced by the engine. When knocking occurs, it generates specific high-frequency vibrations that the sensor is designed to detect. The sensor itself is usually a piezoelectric transducer, which converts mechanical vibrations into an electrical signal. This electrical signal is then sent to the engine control unit (ECU).

Upon receiving a signal indicating knocking, the ECU takes corrective action. The most common response is to retard the ignition timing, meaning the spark plug fires later in the combustion cycle. This delay allows more time for the fuel-air mixture to burn more smoothly, thereby eliminating the knocking. In some cases, the ECU might also adjust fuel injection timing or even temporarily reduce engine power to protect the engine.

Knock sensors are crucial for optimizing engine performance and longevity. They allow modern engines to operate at higher compression ratios and with more advanced ignition timing than would otherwise be possible, leading to improved fuel efficiency and power output, while simultaneously preventing destructive detonation.