The Diesel Particulate Filter (DPF) has been a mandatory component of modern construction equipment diesel engines since the introduction of EU emission stage IIIB/Tier 4i. It filters up to 99% of soot particles from exhaust gas, thereby drastically reducing fine dust pollution on construction sites.
The filter consists of a honeycomb-shaped ceramic body (typically silicon carbide or cordierite) with alternately blocked channels. Exhaust gas flows through the porous channel walls, where soot particles are trapped. Regeneration — the burning off of accumulated soot — occurs automatically at approximately 600 °C, either passively through exhaust gas temperature or actively through post-injection of fuel.
In conjunction with SCR catalytic converter (AdBlue/DEF) and diesel oxidation catalyst (DOC), the DPF forms the exhaust aftertreatment system for Stage V. Problems arise when machines operate continuously at idle or part load — the exhaust gas temperature is then insufficient for regeneration. Manufacturers such as Cat, Komatsu, and Liebherr therefore integrate automatic regeneration cycles into engine control systems.