Diesel Particulate Filter
What is a Diesel Particulate Filter (DPF)? How does it work?
The diesel particulate filter, generally called DPF, is used in diesel engines to clean harmful particles from the exhaust gas.
Harmful particles in the burnt fuel-air mixture coming out of the engine are accumulated in the particulate filter and their release to nature is prevented. These particles are burned by increasing the exhaust gas temperature (by regeneration), thus preventing the pollution of nature. During regeneration, the exhaust gas temperature is seen by the ecu. With the help of the heat sensors on the DPF, the temperature information is sent to the E.C.U and it is possible to calculate the exact amount of fuel required to increase the exhaust temperature.
Regeneration
In order to prevent clogging of the DPF, the particles accumulated in the filter should be cleaned by burning regularly. Regeneration has different strategies.
Passive Regeneration
Particles are continuously incinerated without the intervention of the E.C.U. This standard is also provided at 3000 rpm at highway speeds. The exhaust gas temperature should be between 350 C and 500 C.
Active Regeneration
In predominantly urban use, the exhaust temperature cannot reach a sufficient temperature to perform passive regeneration. Soot cannot be cleaned and accumulates in the filter. When it reaches the occlusion threshold (18 grams), E.C.U. triggers active regeneration. The degree of carbon deposition in the DPF E.C.U. It is calculated using 2 models programmed in
A model based on the driver profile that calculates saturation based on a specific signal pattern from the exhaust gas temperature sensors and the oxygen sensor,
A model that calculates saturation according to the direction of the signals it receives from the differential pressure sensor, temperature sensors and air flow meter.
Pressure difference sensors located on the exhaust between the inlet and outlet of the DPF measure the pressure differences in the filter that reach saturation. When the clogged filter is detected with the help of sensors, the voltage to the E.C.U. is increased. E.C.U. in this way, it pulls the exhaust gas temperature to the 550 C – 650 C band. To ensure this temperature increase;
Adjusts the airflow,
The EGR valve is disabled.
Forced Regeneration
At very short distances it is impossible to reach the temperature required for DPF regeneration. When the saturation level reaches 24 grams, the DPF fault light comes on in the speedometer. This signal tells the driver to perform a regeneration route; that is, sufficient temperatures must be reached for the regeneration of the DPF, the vehicle must be operated at high speed for a certain distance.
Manual Regeneration
If the forced regeneration is not successful and the saturation has exceeded the threshold to 40 grams, the glow plug and engine warning light will illuminate on the indicator. In this case, active regeneration E.C.U. to prevent filter deterioration. blocked by. At this point, the DPF should be serviced by experienced technicians.
If the saturation exceeds the 45 gram threshold, regeneration is no longer possible. Since the DPF cannot be cleaned at this point, it must be replaced.
Mileage Regeneration
This regeneration method depends on the travel distance. It prevents the DPF from exceeding an unhealthy level of saturation. Regardless of fill level, E.C.U. active regeneration automatically triggers when no regeneration is activated for the last 750 – 1000 km.
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