Ricardo UK Limited

Iveco Fiat S.p.a.

Fabrizio Conicella

Richard Cornwell

A piston for a four valve direct injection diesel engine defines a combustion chamber comprising a recess () in the piston crown, which is rotationally symmetrical about the axis of the piston in axial cross-section and is defined by a base and a side wall. A generally conical projection () is upstanding from the base. The recess () includes a lower toroidal portion () and an upper portion (), whose diameter progressively increases towards the piston crown. The upper and lower portions of the recess are separated by an annular, arcuate lip () extending into the recess. The included angle of the conical projection () is between 104&#xb0; and 108&#xb0;, the maximum depth of the recess () is between 13% and 22% of the diameter of the piston, the conical projection () merges with the base of the recess along a circular line whose diameter is between 38% and 44% of the diameter of the piston, the diameter of the lip () is between 54% and 59% of the diameter of the piston, the line of minimum diameter of the lip () is situated at a distance between 5% and 10% of the diameter of the piston from the plane of the piston crown and the diameter of the upper portion () of the recess increases from 54% to 59% of the diameter of the piston at the line of minimum diameter of the lip to between 72% and 76% of the diameter of the piston at the line where the side wall of the recess intersects the plane of the piston crown.

Direct injection diesel engines

An internal combustion engine provided with a decompression-type braking system and with a turbocharger having a variable geometry turbine, in which the effective flow section of the gases entering the turbine under the maximum braking power condition is maintained at least equal to a safety limit value calculated on the basis of geometrical characteristics and of limit values of operating parameters of the engine and of the turbocharger for the purpose of achieving the maximum braking power compatible with the safety of the engine and of the turbocharger.

Growing community of inventors

Turin, Italy

Fabrizio Conicella