Varvtalsbegränsaren

Varvtalsbegränsaren, often referred to as a rev limiter in English, is a device or a software function in an internal combustion engine that prevents the engine from exceeding a predetermined rotational speed, measured in revolutions per minute (RPM). Its primary purpose is to protect the engine from mechanical damage that can occur at excessively high RPMs.

Engines have a range of operational speeds, and exceeding the upper limit can lead to severe consequences. Components such as pistons, connecting rods, crankshafts, and valve train parts are subjected to immense forces at very high speeds. If these forces surpass the material strength or design limits, catastrophic failure can result. The varvtalsbegränsaren acts as a safety net to avoid such scenarios.

There are typically two main types of varvtalsbegränsare: ignition cut and fuel cut. An ignition cut limiter interrupts the spark at each spark plug when the RPM limit is reached, causing the engine to misfire and effectively slowing down. A fuel cut limiter, on the other hand, stops the fuel supply to the injectors, starving the engine of combustion. Both methods aim to reduce the engine's power output and prevent further acceleration in RPM.

Modern vehicles almost universally incorporate electronic varvtalsbegränsare, managed by the Engine Control Unit (ECU). These are highly precise and can be programmed to operate at specific RPMs tailored to the engine's design and intended use. In some performance or racing applications, the varvtalsbegränsare might be set at a higher RPM compared to a standard road car, reflecting the reinforced internal components and performance-oriented design of such engines.