PURPOSE: To raise the efficiency of filter regeneration in a unit provided with a soot-filter in an exhaust line and a regeneration device containing a burner for regenerating the filter by enabling a portion of the air charge from a supercharging device to be supplied to an air inlet of a burner.

CONSTITUTION: A soot-filter unit 1a arranged in an exhaust line 4 of a four cylinder diesel engine 5 having a supercharging device 2 is arranged downstream of an exhaust turbine 3 for driving a compressor 6 in a suction line of the supercharging device 2. A regeneration device 9 containing a burner 10 arranged in an exhaust line 4 is arranged upstream of such a filter unit 1a. A connection pipe 12 is provided extending from a suction system 8 of the engine 5 to an outlet of the compressor 6 of the supercharging device 2. A solenoid valve 13 which is a regulating device is arranged in the midway of the connection pipe 12. In this way, it is possible to introduce the combustion air of which the volume is regulated into a combustion air inlet of the burner 10.