Patent ID: 9702316
Date: 2017-07-11
CPC Classifications: F02B,F02D,Y02T

Claim:
1. A spark-ignition direct injection engine, comprising: an engine body having a cylinder; a fuel injection valve for injecting fuel into the cylinder to form a gas mixture therein; a fuel pressure setting mechanism for setting a pressure of the fuel to be injected by the fuel injection valve; an ignition plug arranged to be oriented toward inside the cylinder and for igniting the gas mixture within the cylinder; and a controller for operating the engine body by controlling at least the fuel injection valve, the fuel pressure setting mechanism, and the ignition plug, wherein the controller switches a combustion mode between a regular compression-ignition mode cycle, with a single, undivided first fuel injection within the regular compression-ignition mode cycle timed at a first fuel injection timing within a predetermined first load range, in which the engine body is operated to perform compression-ignition combustion where the gas mixture within the cylinder self-ignites to combust, and a spark-ignition mode cycle, with a single, undivided second fuel injection within the spark-ignition mode cycle timed at a second fuel injection timing within a predetermined second load range that is other than the first load range, in which the engine body is operated to perform spark-ignition combustion where the ignition plug is controlled to ignite the gas mixture within the cylinder to combust, wherein within the first load range, the controller controls the fuel injection valve to perform the single, undivided first fuel injection within the regular compression-ignition mode cycle at the first fuel injection timing, wherein within the second load range, the controller controls the fuel injection valve to perform the single, undivided second fuel injection within the spark-ignition mode cycle at the second fuel injection timing, wherein during at least one or a plurality of predetermined compression-ignition transitional cycles immediately following the spark-ignition mode cycle and immediately preceding the regular compression-ignition mode cycle, the controller operates the engine body in a compression-ignition initial mode in which fuel pressure is set to be a high fuel pressure of 30 MPa or above by using the fuel pressure setting mechanism and the fuel injection valve is controlled to perform, within the first load range, a single, undivided retarded fuel injection within each predetermined compression-ignition transitional cycle with a retarded fuel injection timing that is retarded later than the first fuel injection timing, so that the retarded fuel injection timing is at least in a period from a late stage of compression stroke to an early stage of expansion stroke so that the gas mixture within the cylinder self-ignites to combust, and after the at least one or a plurality of predetermined compression-ignition transitional cycles ends, the controller controls the engine body to resume performing a fuel injection at the first injection timing within the regular compression-ignition mode cycle, and wherein crank angles of the compression stroke are evenly divided in thirds into an early stage, a middle stage, and the late stage, and crank angles of the expansion stroke are evenly divided in thirds into the early stage, a middle stage, and a late stage.