Patent ID: 8229650

Claim:
An electronic control unit of an engine, capable of injecting fuel in expansion and/or exhaust strokes (expansion/exhaust stroke injection) at a time of warming-up of a catalyst, comprising: said electronic control unit controlling fuel injection such that when a temperature of the catalyst rises higher than a predetermined temperature and a fuel injection amount Ti 3 rd RQ required for the expansion/exhaust stroke injection is smaller than a minimum fuel injection time Timin of an injector, a ratio Rti 3 rd of the expansion/exhaust stroke injection to a predetermined cycle period PRD 3 RDMAX and an injection period PRD 3 RD are calculated by the following equations: Rti 3 rd=Ti 3 rdRQ/Timin, and PRD 3 RD=Rti 3 rd*PRD 3 RDMAX, and, under a constraint of the minimum fuel injection time Timin, fuel injection in the expansion/exhaust strokes is performed for the injection period PRD 3 RD over each cycle period PRD 3 RDMAX, and the expansion/exhaust stroke injection is not performed in the cycle periods PRD 3 RDMAX other than the injection period PRD 3 RD.