Abstract: In the case that an engine is operated in a state where an in-cylinder air/fuel ratio is lean in a stratified combustion region and a fuel cut control is performed under a predetermined condition, when catalysts are in a low temperature state where a purification performance is deteriorated or when a NOx absorptive amount of the lean NOx catalyst, a control procedure for exhaust air/fuel state at a recovery timing from the fuel cut control so that a driving sensation is improved while maintaining the exhaust purification performance by the catalysts. When the fuel cut control is terminated and the engine shifts into the stratified combustion region, if a catalyst temperature is at or below a set temperature or a NOx absorptive amount is at or above a set amount, the in-cylinder air/fuel ratio of the engine is correctively enriched and the exhaust air/fuel state is enriched.

Abstract: A direct injection engine of sparking ignition type has a catalyst in an exhaust passage and a fuel injection valve for directly spraying fuel into a combustion chamber. An ECU for controlling the engine is provided with a setter and an air-fuel ratio controller. The setter sets an enriched region where an air-fuel ratio is smaller than a stoichimetric air-fuel ratio in a high engine speed and load area of an operating region of the engine, a stoichimetric air-fuel ratio region where the air-fuel ratio is equal to the stoichimetric air-fuel ratio in an area of the operating region of the engine having lower engine speed or load than the enriched region, and a lean region where the air-fuel ratio is larger than the stoichimetric air-fuel ratio between the stoichimetric air-fuel ratio region and the enriched region. The air-fuel ratio controller controls the air-fuel ratio based on the setting by the setter.

Abstract: A catalyst light-off device for a direct injection engine comprises a temperature state identifier (31) for judging the temperature state of a catalyst (22) for converting exhaust gases, a fuel injection controller (33) for controlling fuel injection from an injector (11), and an ignition timing controller (35). When the catalyst is in its unheated state in which its temperature is lower than its activation temperature, the fuel injection controller (33) causes the injector (11) to make split injection during a period from an intake stroke to an ignition point including a later injection cycle which produces a mixture having local unevenness and an earlier injection cycle which produces a uniform and lean mixture, and the ignition timing controller (35) retards the ignition point.

Abstract: To reduce the amounts of HC, NOx and other emissions from a direct injection engine when a catalyst is still in its unheated state, and to promote catalyst quick light-off operation by increasing the temperature of exhaust gases, a control device comprises a temperature state identifier (31) for judging the temperature state of a catalyst (22) and a fuel injection controller (33) for controlling fuel injection from an injector (11).

Abstract: A control device for a direct injection engine includes an identifier for judging whether a catalyst is in its unheated state in which its temperature is lower than its activation temperature, an engine temperature state detector for sensing the temperature state of the engine, and a fuel injection controller for controlling fuel injection from the injector. The fuel injection controller controls an injector in such a way that it makes at least two-step split injection including an earlier injection cycle performed during an intake stroke and a later injection cycle performed in a middle portion of a compression stroke or later when the catalyst is in its unheated state, and the later injection cycle is retarded when the catalyst is still in its unheated state but the engine temperature has become higher than a specified temperature compared to a case where the temperature of the engine is equal to or lower than the specified temperature.

Abstract: In steps S25 to S42, in order to activate an inactive catalyst earlier, the air-fuel ratio in a combustion chamber is set to be &lgr;≈1 during a period T1 after engine start until catalyst light-off at around 50% HC purifying ratio immediately after the HC purifying ratio begins to rapidly rise, before the catalyst warms up, divisional injection is made at least during the period T1 required until light-off is reached, and a swirl is weakened during the period T1 compared to a latter period which follows this period T1. The divisional injection is made and the swirl is strengthened even during the latter period.

Abstract: An automotive engine is generally provided with an exhaust gas pipe assembly extending generally rearwardly from the engine for discharging exhaust gases. The exhaust gas pipe assembly includes a plurality of exhaust gas pipes, at least one chamber formed intermediately of the exhaust gas pipe assembly, a first support member disposed in the proximity of the engine, and at least one second support member disposed in the proximity of the chamber. The first support member can effectively absorb relative displacement between the exhaust gas pipe assembly and the vehicle body in a direction transversely of the vehicle body whereas the second support member can effectively absorb relative displacement between the exhaust gas pipe assembly and the vehicle body in a direction longitudinally of the vehicle body.

Abstract: An exhaust system for a power plant which includes an engine and a transmission connected with the engine, the exhaust system includes a plurality of independent exhaust pipes connected with the engine, the plurality of independent exhaust pipes being combined into a single combined portion, a common exhaust pipe connected with the combined portion at an upstream end portion thereof. The common exhaust pipe is supported on the transmission at an intermediate supporting portion thereof. One of the plurality of independent exhaust pipes and an upstream part of the common exhaust pipe are, when viewed from above, substantially parallel with a rolling axis of the power plant.

Abstract: A particular cooling water passage structure is installed in a V-type engine having two cylinder banks offset in a lengthwise direction of a crankshaft. Each bank is provided with inlet ports, provided to admit a cooling water flow. Each inlet port communicates with a lengthwise front end portion of the water jacket. The inlet port of one of the cylinder banks, which is offset forward relative to the other, is further in communication with a side portion, adjacent to the front end portion, of the water jacket. The inlet ports have apertures which open at the same location in the lengthwise direction. Piping, connected to the inlet ports, is provided in a space formed between the offset cylinder banks.