Abstract: A diesel engine includes a turbocharger, an intercooler, a particulate filtering unit, and an EGR cooler. EGR ratio of intake air, injection timing of an injection nozzle, and excess air ratio to fuel are controlled depending upon engine-operating load. Lean premixed compression ignition is performed at low engine load; low temperature combustion at low excess air ratio with high EGR ratio is performed at medium engine load; and normal EGR combustion is performed at high engine load.

Abstract: A diesel engine comprising a fuel injection device and a controller for controlling the fuel injection device in accordance with an operating condition of the engine. The fuel injection device effects a preliminary injection for injecting fuel into a cylinder during a period from the initial part of an intake stroke to the middle part of a compression stroke and a main injection for injecting fuel into a combustion chamber in the vicinity of a top dead center of the compression stroke, whereby lean mixture is formed and a maximum combustion temperature in the combustion chamber is decreased to suppress generation of NOx and to reduce emission of black smoke.

Abstract: An internal combustion engine has an engine-braking master piston for a first cylinder actuated by a first rocker arm which, in turn, is actuated by the inlet push rod of another cylinder and an exhaust-gas-recirculation master piston is provided which is actuated by a second rocker arm which, in turn, is actuated by the exhaust push rod of another cylinder. An oil passage selector valve is provided for selectively switching over the hydraulic pressures produced by the engine-braking master piston and exhaust-gas-recirculation master piston to an oil passage to actuate a slave piston and open an exhaust valve of the first cylinder. To effect engine braking, the exhaust valve of the first cylinder opens as the piston is near its top dead center position at the end of the compression stroke or at the beginning of the expansion stroke.

Abstract: In addition to an engine-braking master piston, an exhaust-gas-recirculation master piston is provided to pressurize an oil having been supplied to an oil passage and open an exhaust valve in a suction stroke. A directional control valve selectively switches transmission of hydraulic pressures produced by the engine-braking and exhaust-gas-recirculation master pistons so that the exhaust valve adjacent to a top dead center in a compression stroke is opened to discharge the compressed air. Exhaust gas recirculation can be effected while braking action by a braking force produced in the compression stroke is ensured.

Abstract: The method by this invention is characterized in that a fuel injection nozzle to inject diesel fuel oil into cylinder and an auxiliary injection nozzle to inject the combustible gas or non-combustible gas into the cylinder are provided, and that said combustible gas or non-combustible gas is injected in the latter stage of the diesel fuel oil combustion. More concretely, a part of the fuel is reformed to combustion gases by a fuel reforming apparatus and the gases are injected, or the combustible gas or non-combustible gas is prepared in another gas cylinder, and this gas is injected in the latter stage of the combustion.