Under the strict standards of the National VI Regulations, many automobile manufacturers have demonstrated their technological strength and explored ways to cope with the new regulations. Among them, the limitation of PN particle quantity has become a new challenge faced by the industry. In order to ensure that PM particulate matter emissions meet standards, National VI vehicles are generally equipped with wall flow DPF. So, what is DPF? How does it actually work?

DPF， The Diesel Particulate Filter is a crucial component of the diesel engine emission system. It is made of ceramic material and its core function is to capture harmful particles in diesel engine exhaust. Through this device, the emission of particulate matter can be significantly reduced, with a decrease of up to 70% -90%.

Moreover, DPF can further convert the captured harmful particles into harmless carbon dioxide. This process is called DPF regeneration and is an important part of DPF technology. So, from the perspective of internal control, what is the working process of DPF?

1. Regeneration triggering conditions

The active regeneration of DPF is not carried out arbitrarily, but requires specific conditions to be met before it can be activated, which usually include the following three conditions:

① Mileage triggers regeneration

When the vehicle reaches the preset mileage, it will trigger active regeneration of the DPF. However, for urban or port short distance vehicles, the inability to maintain stable speed and load for a long time results in consistently low exhaust temperatures, which limits the effectiveness of passive regeneration. This may cause the DPF to become clogged due to particulate matter accumulation before reaching the preset regeneration mileage.

② Differential pressure sensor monitoring blockage

Due to uneven distribution of particulate matter within the DPF, there may be severe accumulation in certain areas that are not detected by the differential pressure sensor. If regeneration is carried out based on such a state, it may damage the DPF. Therefore, the main function of the differential pressure sensor is to monitor the blockage or removal of faults in the DPF, rather than directly triggering regeneration.

③ Soot cumulative model reaches limit, triggering regeneration

During the operation of the vehicle, the ECU will continuously monitor the vehicle's operating conditions and calculate a value based on this. When this value reaches the preset limit, the regeneration mechanism will be triggered. Compared to the first two methods, this method has a wider range of applications, and therefore, it is widely adopted as a triggering condition for regeneration during the National VI emission standard stage.