Patent ID: 9464592
Filing Date: 2016-10-11
CPC Classification: F01P,F02B,F02F,F16J

Claim Text:
1. An internal combustion engine including at least one cylinder with longitudinally-separated exhaust and intake ports and a pair of pistons disposed in opposition to one another in a bore of the cylinder, each piston including a piston body with a crown at one end, an end surface on the crown, in which an end surface of a first piston has a bowl that cooperates with the end surface of an opposing piston to define a combustion chamber, at least one ring groove in the piston sidewall near the crown, an annular thermally-resistant cavity formed in the piston sidewall along a circumference of the piston body and positioned between the end surface and the at least one ring groove, and one of a band, a flange, and a pair of opposing flanges covering the cavity to form a chamber that contains a near-vacuum.