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(11) | EP 0 294 092 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Heat-insulating engine structure |
| (57) In order to improve the suction efficiency and the cycle efficiency, a heat-insulating
engine structure (10) of the invention has a planar and thin-walled piston head surface
portion (4) of a ceramics material to be exposed to combustion gases. A combustion
chamber (15) is formed not on the side of the piston head but on the side of a cylinder
head. Namely, the piston head is defined by the cooperation of a cylinder head bottom
wall portion (26) having a lowered central portion and a raised outer peripheral portion
(18) and a cylinder liner upper portion (28) including an upper tubular part of a
substantially square cross-section and a lower cylindrical part. The cylinder head
bottom wall portion has an inclined surface radially upwardly extending from the central
portion to the outer peripheral portion. Intake and exhaust valves (21, 27) are associated
with valve seats formed in the inclined surface. A fuel injection nozzle (25) is disposed
substantially centrally of the cylinder head bottom wall portion. The sides of the
square tubular part are operative to agitate a swirl to facilitate uniform mixture
of fuel and air thereby assuring that the fuel and air are mixed instantaneously
in a zone adjacent to the top dead center of the piston. |