| 摘要 |
An internal combustion engine has first and second cylinders (12, 14), the first cylinder (12) having a larger swept volume than the second cylinder (14) and the second cylinder being formed in the crown of the first cylinder. First and second pistons (16, 18) are reciprocable respectively in the first and second cylinders (12, 14), the second piston (18) being formed as a protrusion on the crown of the first piston (16). The first cylinder has an air inlet (25) and an exhaust outlet (27) whilst a first fuel source (34) provides fuel to the second cylinder (14). The second piston has a crown (35) which is spaced from and connected to the crown (36) of the first piston and which has an edge (37) which is relatively thin in the axial direction compared to the spacing of the first piston crown from the second piston crown. This defines a combustion space (20) between the piston crowns and a side wall (14a) of the second cylinder (14) when the pistons are substantially at the inner dead centre position. The combustion space (20) communicates with both cylinders (12,14) during part of the expansion stroke. Inhibiting means is also provided for inhibiting ingression prior to the pistons (16,18) arriving at or adjacent the inner dead centre position. This can take the form of a gap (128) between the second piston crown (35) and the second cylinder side wall (14a) with a peripheral groove (39) in the second cylinder wall at its upper end to enable the fuel/air mixture in the second cylinder (14) above the crown (35) to bypass the piston crown when the latter is at its inner dead centre position and enter the combustion space (20).
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