DPF diesel particulate filter

The core component of DPF is the filter carrier, which is mainly divided into two categories: ceramic based and metal based. Ceramic based DPF carrier materials include cordierite, silicon carbide, mullite and zirconia, while metal based DPF carrier materials include sintered metal, foam metal and wire mesh. In practical applications, cordierite and silicon carbide are the most common filter materials.

The pore size of DPF diesel particulate filters is usually in the micrometer range, which is significantly larger than the size of soot particles. Therefore, these micropores cannot directly achieve purification effects. In fact, DPF captures particulate matter through four main mechanisms: diffusion mechanism, interception mechanism, inertial collision mechanism, and gravity deposition mechanism.

DPF active regeneration monitors exhaust back pressure through a differential pressure sensor. When the back pressure reaches a certain value, the ECU will control a dedicated nozzle to inject diesel into the exhaust management. In this way, the combustion flame formed in the exhaust pipe will raise the internal temperature of the DPF to 600 ℃~620 ℃, thereby burning the captured particulate matter into CO2 and discharging it. Passive regeneration of DPF involves adding additives to the fuel to reduce the temperature of particle combustion, allowing captured particles to burn into CO2 at lower temperatures and be emitted.

In addition, DPF on diesel engines and GPF on gasoline engines share similarities in filtration mechanisms. They all use wall flow filters to capture particulate matter by alternately plugging honeycomb porous ceramic filter bodies. However, due to the substantial differences in exhaust emissions between gasoline and diesel engines, there are also many differences between GPF and DPF. For example, the particulate matter emissions from gasoline engines are approximately 10-30 times that of diesel engines, which drives the two to choose different optimal filtration technologies.

There is also a significant difference between GPF and DPF in terms of regeneration timing. Due to the relatively high exhaust temperature of gasoline engines, especially under urban driving conditions, the output temperature of gasoline engines ranges between 300 and 500 ° C, and can even reach 700 ° C at high speeds. Although these temperatures are sufficient to maintain passive regeneration of GPF, gasoline engines operating at stoichiometric ratios often have insufficient oxygen in the exhaust. Therefore, the regeneration of GPF usually occurs during vehicle deceleration, when reducing fuel supply to ensure sufficient oxygen in the exhaust. GPF with oxygen storage capacity can achieve active and passive regeneration in a short period of time.

In contrast, DPF requires parking regeneration. During the parking regeneration process, the engine will increase idle speed, thereby increasing the exhaust temperature upstream of DOC. When the upstream temperature of DOC reaches, the HC injection system is used to control the exhaust temperature, keeping the upstream exhaust temperature of DPF at a regeneration temperature of about 600 ℃, to ensure that the particles accumulated in DPF can be fully burned. Therefore, the regeneration time of DPF is relatively long.

The difference in soot loading rate | Gasoline engines have relatively less soot emissions, and their soot oxidation rate is much faster than diesel engines. Therefore, the soot loading rate in GPF is kept at a low level, avoiding excessive heat release caused by soot oxidation and ensuring good thermal durability.

Price difference | Due to its low ash load, GPF can adopt a more compact and cost-effective design. The reduction in volume means the use of fewer precious metal materials, which typically requires larger volume filters in diesel vehicles to accommodate 1.5 to 2.5 times the engine displacement, while GPF can achieve a volume smaller than the engine displacement, thereby reducing replacement costs.

In summary, the main difference between DPF and GPF lies in the type of fuel used in the engine. Regular maintenance is essential for any type of particle trap. The blockage of particle traps not only affects engine performance and vehicle fuel consumption, but also shortens their service life, which is something that every car owner does not want to see.