Abstract:
When a catalytic converter in an exhaust passage is in an un-activated state, an intake air amount is increased, as compared to when the converter is in an activated state under the same engine operation condition, and an ignition timing is retarded beyond a TDC of a compression stroke. The ignition timing is set such that a retard amount thereof from the TDC becomes larger as an external load causing a rotational resistance of an engine becomes lower. A valve opening start timing of an exhaust valve is set such that, when the external load is lower than a given reference load, the valve starts opening, before an in-cylinder pressure reaches a peak, according to combustion of an air-fuel mixture ignited at the above ignition timing, in a subsequent expansion stroke, wherein the in-cylinder pressure is based on an assumption that the valve is maintained in a valve-closed state.
Abstract:
A controller (an engine controller 100) feeds a fuel into a cylinder 11 through a fuel feeder (including a fuel injection valve 53 and a fuel feeding system 54) when the cylinder 11 is in an intake stroke and a compression stroke and if an engine body (an engine 1) is both in a cold running phase and under a heavy load. The engine body at or below a predetermined temperature is in the cold running phase. The load applied to the engine body is heavy when the engine body is under at least a predetermined load. The controller also lowers the upper limit of the charging efficiency of the engine body as the vaporization rate of the fuel fed into the cylinder decreases.
Abstract:
An intake system of an engine supplies gas at least containing fresh air to each cylinder. The system includes an EGR passage that communicates with an internal space of a downstream intake passage and introduces some EGR gas into the downstream intake passage. The EGR passage includes a projected section in a substantially polygonal or cylindrical shape that is projected to the internal space of the downstream intake passage. The projected section is formed in such a shape that a projection length H1 in an outer circumferential surface on an upstream side is longer than a projection length H2 in an outer circumferential surface on a downstream side.
Abstract:
In a flexible-fuel engine capable of using fuel containing alcohol as fuel to be combusted in a cylinder, the geometric compression ratio is set to 12 or more, the engine is started by using fuel containing alcohol, an intake valve closing timing at an engine start time is set to an advance angle side than a first reference timing being a timing corresponding to a most retarded angle position out of intake valve closing timings capable of starting the engine in combusting fuel of alcohol 100% in the cylinder at a first intake temperature, and is set to a timing on a retarded angle side than a second reference timing being a timing corresponding to a most advanced angle position out of intake valve closing timings capable of avoiding pre-ignition in combusting fuel of gasoline 100% at an engine start time at a second intake temperature.