What is a gasoline particulate filter and how does it work?

Diesel cars have been equipped with particulate filters for many years, and now gasoline cars are also equipping them to reduce pollution…

More and more gasoline cars are equipped with gasoline particulate filters to meet the latest stringent emissions limits. According to Volkswagen, particulate emissions of some of its gasoline models can be reduced by up to 95% by installing a filter in the exhaust system.

Why do gasoline particulate filters appear on the market?

Gasoline particulate filters, also known as OPF (otto partikelfilter) or GPF (gasoline particulate filters). They became necessary due to European Union regulations on the amount of particulate matter that gasoline engines are allowed to emit.

Particles from gasoline engines have been strictly controlled since Euro 5. However, replacing the old test cycle of the NEDC laboratory (New European Driving Cycle) with the WLTP mode (Worldwide Harmonised Light Vehicles Test Procedure) harsher from Euro 6c onwards (joined by RDE, Real Driving Emissions, from Euro 6d) has made compliance much more difficult. For many automobiles, particulate matter emissions need to be drastically reduced, resulting in an increase in OPF.

What is a gasoline particulate filter?

The gasoline particulate filter is usually located on the bottom of the catalytic converter, usually inside a metal canister that may look like an additional silencer. When you open it up you will see a ceramic honeycomb structure, the same way you would with the DPF (diesel particulate filter).

As exhaust gas passes through this unit, the honeycomb filter traps excess nitrogen oxide, carbon monoxide and hydrocarbon particles. Due to the high temperature of the filter, they all burn out, creating a little water, nitrogen, and carbon dioxide in the process. And finally, it helps to reduce about 90 to 95% of the particles in the exhaust.

How does a gasoline particulate filter work?

The system is available on Volkswagen Group cars, such as the Volkswagen Up GTI and newer models with 1.4 TSI, 1.5 TSI,  2.0 liter petrol engines, it acts like a three-way catalytic converter, through which the exhaust gas flows after exiting the engine and towards the exhaust manifold.

This unit is located directly behind the engine, near the turbocharger. This helps it heat up quickly – which is important because it needs to be hot to work properly.

The exhaust gas is passed through a filter, where trapped unwanted particles of hydrocarbons (HC), nitrogen oxides (NOx) and carbon monoxide (CO) are heated and reduced to a small amount of carbon dioxide (CO2), nitrogen and water.

Once out of the filter, the exhaust gases pass through a second conventional three-way catalytic converter mounted below the floor. This ensures exhaust emissions comply with the latest level of EU6c emission standards even when the engine is running normally.

Which cars are equipped with a gasoline particulate filter?

Volkswagen has committed to introducing particulate filters to its petrol models in 2016, starting with the Tiguan and above. Gasoline versions of the various Ford, Mercedes-Benz and Porsche models, including the Mustang, S-Class and Macan, also have particulate filters.

This technology has also been applied on most new petrol car models introduced since September 2018 to meet EU6c requirements.

Does the gasoline particulate filter need maintenance?

According to manufacturers, cars with a gasoline particulate filter do not need to regularly run at higher speeds for a short time to avoid soot like diesel engines.

Gasoline particulate filters are not as prone to clogging as diesel engine particulate filters because gasoline engines heat up and run hotter than diesel engines, so more soot that accumulates in the filter is burned. In addition, Porsche says the electronic controls in its cars will detect when soot particles need to be ignited and raise the exhaust temperature to do so.

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Written by Fields Nguyen

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