Filtering device for diesel engine exhaust gas

A filtering device for diesel engines exhaust gas, comprising a metal shell having a longitudinal axis, an inlet pipe, an outlet pipe, a single frustoconical first shell end, and a single planar second shell end, the first and second shell ends being orthogonal to the longitudinal axis, the frustoconical first shell end having angled walls extending intermediate a pipe interface plane and a flow diversion plane, the metal shell defining a cavity with a filtering device body extending intermediate the intake and outlet pipes, the filtering device body comprising primary and secondary filtering segments, and an end-located diaphragm, the end-located diaphragm transversely extending in the flow diversion plane adjacent the pipe interface plane for altering the flow of engine exhaust gases within the frustoconical first shell end, the primary and secondary filtering segments being arranged about said longitudinal axis of the shell in such a way as to define, inside the shell, an outer chamber and an inner chamber, the said chambers communicating with said intake pipe and said outlet pipe in such a way that during use, the flow of the engine exhaust gases is forced from the outer chamber to the inner chamber —or vice versa— and wherein the flow of the engine exhaust gases is forced from a central chamber and from the outer chamber to said inner chamber —or vice versa—, thus assuming a radial component of velocity with respect to the longitudinal axis of the shell, wherein said filtering segments are composed of a plurality of layers of metal foam sheets set in the path of communication between said intake pipe and outlet pipe, wherein the porosity of said metal foam layers is variable.