Component description for the diesel particulate filter

P14.40-2046-06

18 Primary catalytic converter

19 Oxidation catalytic converter

21 Rear muffler

114 Diesel particulate filter (DPF)

Location

The DPF is located at the center at the vehicle underfloor.

Task

The DPF filters, stores and burns the particulate matter (particles) (PM) which arise during the combustion in the engine.

Design

The diesel particulate filter consists of a ceramic honeycomb filter body (monolith) made out of silicon carbide, which is coated with the rare metal platinum. The passages of the diesel particulate filter are opened alternatively at front and rear and are separated from each other through the porous filter walls (C) of the honeycomb filter body (monolith).

P14.40-2027-06

81 Exhaust gas flow

82 ceramic monolith

83 Plug

84 Insulation

85 Housing

Function

The unfiltered exhaust gas flows through the porous ceramic monolith of the DPF.

The PM are physically held back in the ceramic monolith of the DPF. To regenerate the DPF, the vehicle load of the DPF is determined by the exhaust gas pressure upstream and downstream of the DPF. The signals are evaluated by the differential pressure sensor (DPF) (B28/8) and transmitted to the CDI control unit (N3/9).

Temperatures above 600°C are necessary for PM oxidation which are not obtained during normal operation of the diesel engine.

The CDI control unit can take the following measures to increase the exhaust gas temperature for this purpose:

 Intake air throttling

 Late injection

 DPF preheating