Unburned fuel venting in internal combustion engines

A cylinder liner configured to be inserted into a cylinder of an internal combustion engine, the cylinder liner comprising:

• a circumferential wall configured to reciprocally guide a piston between a top dead center (TDC) and a bottom dead center (BDC), the piston separating the cylinder liner into an upper piston section and a lower piston section, and including a piston ring assembly having at least one piston ring configured to sealingly contact the circumferential wall and having a piston ring assembly thickness (D), such that an annular crevice is defined by the circumferential wall, the piston, and the at least one piston ring, the annular crevice having an annular crevice volume;
• and
• a plurality of venting grooves each extending within the cylinder in axial direction over a length (L) being greater than the piston ring assembly thickness (D), the plurality of venting grooves having a venting volume and being configured and positioned to fluidly connect the annular crevice to the lower piston section, only when the piston has a position corresponding to a crank angle range of about 85° to 95° and about 265° to 275° after the top dead center (TDC), the venting volume being in the range from 15% to 60% of the annular crevice volume.

A cylinder liner configured to be inserted into a cylinder of an internal combustion engine, the cylinder liner comprising:

• a circumferential wall configured to reciprocally guide a piston between a top dead center (TDC) and a bottom dead center (BDC), the piston separating the cylinder liner into an upper piston section and a lower piston section, and including at least one piston ring configured to sealingly contact the circumferential wall and having a piston ring thickness (D), such that an annular crevice is defined by the circumferential wall, the piston, and the at least one piston ring;
• and
• a plurality of venting grooves vertically disposed in the circumferential wall and each of the venting grooves having a length (L) that is greater than the piston ring thickness (D), the venting grooves being configured and positioned to fluidly connect the annular crevice to the lower piston section, only when the piston has a position corresponding to a crank angle range of about 85° to 95° and about 265° to 275° after the top dead center (TDC).