Abstract: This engine structure includes: a cylinder block in which a cylinder bore is formed; a piston provided in the cylinder bore; a cylinder head provided to an upper portion of the cylinder block in a manner to seal the cylinder bore; and a ring that is inserted in the upper end portion of the cylinder bore and has an inner diameter that is smaller than the diameter of the cylinder. A first abradable layer that is worn down by contact with an outer peripheral surface of the piston is formed on an inner peripheral surface of the ring.

Abstract: An internal combustion engine includes: a cylinder in which a piston reciprocates; a cylinder head positioned above the cylinder; a gasket disposed between the cylinder and the cylinder head; a stepped portion formed at an upper end portion of an inner peripheral surface of the cylinder; a ring member having a cylindrical shape provided to the stepped portion; and a seal member that is provided on an upper surface of the ring member and is sandwiched between the ring member and the cylinder head.

Abstract: An internal combustion engine includes: a cylinder in which a piston reciprocates; a stepped portion that is formed on an upper end portion of an inner peripheral surface of the cylinder; and a ring member having a cylindrical shape provided to the stepped portion. The thickness of the ring member decreases toward the bottom dear center of the piston, and an outer peripheral surface of the ring member is an inclined surface, where a lower end of the outer peripheral surface is positioned closer to the center in the radial direction of the ring member than an upper end of the outer peripheral surface.

Abstract: An internal combustion engine includes: a cylinder in which a piston reciprocates; a cylinder head positioned above the cylinder; a gasket disposed between the cylinder and the cylinder head; a stepped portion that is formed at an upper end portion of an inner peripheral surface of the cylinder and positioned below the gasket; a ring member having a cylindrical shape provided to the stepped portion; and a protrusion portion that is formed in a manner to protrude from the ring member and bites into a lower surface of the gasket.

Abstract: An internal combustion engine includes: a cylinder in which a piston reciprocates; a cylinder head positioned above the cylinder; a gasket disposed between the cylinder and the cylinder head; a stepped portion formed at an upper end portion of an inner peripheral surface of the cylinder; a ring member having a cylindrical shape provided to the stepped portion; and a seal member that is provided on an upper surface of the ring member and is sandwiched between the ring member and the cylinder head.

Abstract: An internal combustion engine includes: a cylinder in which a piston reciprocates; a cylinder head positioned above the cylinder; a gasket disposed between the cylinder and the cylinder head; a stepped portion that is formed at an upper end portion of an inner peripheral surface of the cylinder and positioned below the gasket; a ring member having a cylindrical shape provided to the stepped portion; and a protrusion portion that is formed in a manner to protrude from the ring member and bites into a lower surface of the gasket.

Abstract: An internal combustion engine includes: a cylinder in which a piston reciprocates; a stepped portion that is formed on an upper end portion of an inner peripheral surface of the cylinder; and a ring member having a cylindrical shape provided to the stepped portion. The thickness of the ring member decreases toward the bottom dear center of the piston, and an outer peripheral surface of the ring member is an inclined surface, where a lower end of the outer peripheral surface is positioned closer to the center in the radial direction of the ring member than an upper end of the outer peripheral surface.