A device for depolluting a heat engine exhaust gases includes an outer
casing (23) delimiting an exhaust gas circulating passageway and a
particle filter (20) mounted in the passageway. The casing (23) includes
a transverse break (34) along its entire periphery, the break (34)
dividing the casing (23) into first and second successive segments (38,
40). The first and second successive segments (38, 40) include two
mutually engaged ends. One outer end of the first segment (38) overlaps
one inner end of the second section (40) along part of the length of the
flow passageway. The outer end of the first segment (38) includes along
its periphery at least one weakened region (50) for varying the
cross-section of the outer end of the first segment (38). The device is
applicable to motor vehicles.