| 摘要 |
PURPOSE:To prevent torque shock or the like in acceleration by setting compression ratio to high one and air-fuel ratio to the lean mixture side in the low load region of an engine, while the compression ratio is altered from high to low one at the same time as the correction of air-fuel ratio to the rich mixture side. CONSTITUTION:A compression ratio changing means comprises a crank-pin-like piston pin connected pivotably to the small end of a connecting rod 23. The position of a piston 3 relative to the connecting rod 23 is varied by utilizing oil pressure supplied from an oil pump 22 through a hydraulic solenoid valve 25 to vary the compression ratio. Then, the air-fuel ratio can be varied by controlling a fuel injection amount from a fuel injection valve 11 with a controller 27 and the air fuel ratio change control and compression ratio change control are adapted to corporate with each other. Namely, the compression ratio is set to high one in the low load region and the air-fuel ratio is controlled to the lean mixture side, while the alteration from the high compression ratio to low one is carried out at the same time as the correction of air-fuel ratio to the rich mixture side.
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