| 摘要 |
A direct-injection, spark-ignition engine of the present invention includes a turbo-charging device which promotes the temperature rise or activation of the exhaust-gas purification catalyst disposed downstream of a turbine during cold start. During engine cold start, the fuel injection by the fuel injector is divided into a leading fuel injection performed during the latter half of the compression stroke, prior to the ignition timing, and a trailing fuel injection performed during the expansion stroke, after the ignition timing. The amount of the intake-air and the amount of the fuel injection are so controlled that the air-fuel ratio in the combustion chamber during the combustion of the fuel by the leading fuel injection (a leading air-fuel ratio) is within the range of 2lambd3, and the air-fuel ratio in the combustion chamber during the combustion of the fuel by the trailing fuel injection (a total air-fuel ratio) is within the range of 1<lambd<2. This raises exhaust-gas temperature with heat from the combustion of the fuel injected in the compression stroke and by the oxidization of the unburned HC from turbine agitation, to raise the exhaust-gas temperature for promoting the temperature rise or activation of the exhaust-gas purification catalyst downstream of the turbine.
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