What is gasoline particulate filter (GPF) and how does it work?

What is GPF?

Automobile GPF refers to gasoline engine particle filter. GPF is a ceramic filter installed in the exhaust system of a gasoline engine. The shape is a cylinder, which is no different from the shape of traditional "three-way catalyst". The difference is the internal air flow channel. GPF is a wall-flow carrier. The inside of the carrier is parallel honeycomb pores. Only one of the adjacent two pores has an inlet open, and the other has only an outlet open. It can capture particulate emissions before they enter the atmosphere. The main function is to reduce particles, and through ECU control, the particles in the trap are oxidized and burned to achieve the purpose of regeneration.

GPF working mechanism

The filtering mechanism of GPF is basically the same as that of diesel engine DPF. Exhaust gas passes through the porous wall at a certain flow rate. This process is called "Wall-Flow”. The wall-flow particulate filter is composed of honeycomb ceramics with a certain pore density. By alternately blocking the honeycomb porous ceramic filter, the exhaust flow is forced to pass through the pore wall and the particles is captured and filtered through the four methods of diffusion, interception, gravity and inertia.

GPF layout plan

GPF is mainly arranged on the exhaust pipe of gasoline engine in three forms. One is integrated with TWC and installed closer to the exhaust manifold, that is a closed-coupled arrangement. The other is directly installed at the downstream position of the TWC, that is under-floor. And the other is the three-way catalyst coated on the GPF substrate to form a "four-way catalyst”.