A four cylinder engine including two outer cylinders valved to operate on a four cycle basis, the outer two cylinders being movable together in opposite directions than the direction of movement together of the two inner cylinders. The two inner cylinders valved to operate on a two-cycle basis. The four cylinders having fuel injectors for injecting an amount of fuel in an associated cylinder so as to cause a self-ignited power event to occur therein during each cycle. The engine, when embodied in a vehicle having a battery energized computer and manually operated accelerator pedal being selectively operated in three power levels: (1) a minimum fuel mode (2) an intermediate fuel mode and (3) a maximum fuel mode. (1) Enabling a two-third fuel saving (two injections out of a possible six) when in minimum fuel mode and (2) a one-third saving fuel (four injections out of a possible six) when in the intermediate mode. The two inner cylinders operate on the fuel sharing principles of the '769 patent when in the intermediate mode.

In an opposed-piston engine which includes a catalytic aftertreatment device in its exhaust system an exhaust gas condition indicating a catalyst temperature of the aftertreatment device is monitored. When the catalyst temperature is near or below a light-off temperature, a catalyst light-off procedure is executed to elevate the temperature of the catalyst.

A fuel system for an engine has a cylinder with an inlet air port, an air box surrounding the inlet air port, and a gaseous fuel injector positioned in the air box and having a nozzle located at the inlet air port. The fuel system also has a gaseous fuel control valve, a fuel supply line fluidly extending from the gaseous fuel control valve to the gaseous fuel injector, a purge valve, and a purge fluid supply line fluidly extending from the purge valve to at least one of the fuel supply line and the gaseous fuel injector. The fuel system also has a return valve and a return line fluidly extending from at least one of the fuel supply line and the gaseous fuel injector.

A uniflow-scavenging-type two-cycle engine includes: a cylinder; a piston that slides in the cylinder; an exhaust port that is provided at a first end of the cylinder; an exhaust valve that opens and closes the exhaust port; a scavenging port that is provided in an inner circumferential surface of a second end of the cylinder in the stroke direction of the piston and inhales an active gas into a combustion chamber in accordance with a sliding movement of the piston; a plurality of fuel injection valves that inject a fuel gas to the active gas, which has been drawn in from the scavenging port to the combustion chamber, to thereby generate a premixed gas; and a fuel injection control unit that varies injection directions of fuel gas injected from a part or all of the fuel injection valves.

The invention concerns a method for controlling the fuel supply to an internal combustion engine at start-up, the engine having a fuel supply system. The invention also concerns a carburetor having a fuel supply system including a main fuel path connecting a diaphragm controlled regulating chamber to a main outlet in the region of the venturi section, the main fuel path including an actively controlled fuel valve, and an idling fuel path branching off from the main fuel path downstream of the valve and ending in at least one idling outlet in the region of a throttle valve, the fuel supply system further including a start fuel line starting upstream or downstream of the fuel valve and ending in at least one start fuel outlet to the intake channel.

An engine is configured such that, during the starting of the engine, when it is being detected that throttle opening has been set at a starting position, if it is detected that the engine speed has exceeded a predetermined speed slightly lower than a speed when a centrifugal clutch becomes an engaged state, a control unit retards the ignition timing from a general angle to a first angle BTDC, and then advances the ignition timing to a second angle at predetermined intervals, and holds the ignition timing at the second angle for a predetermined time period, thereby preventing the engine from stopping due to fouling on the spark plug while suppressing the engine speed at the speed when the centrifugal clutch becomes the engaged state, or less.

To meet stringent emission standards and improve performance of two-stroke crankcase-scavenged engines, the muffler (13) of the engine is provided with mixing means (130, 31) for mixing the exhaust gases (42) resulting from the mixture participating in combustion and gases resulting from scavenging, so that a substantially homogenous gaseous mixture is formed within the muffler (13), and means (81) for sensing oxygen concentration is located in the homogeneous gaseous mixture and are configured to provide an output value to a control unit (80) for controlling supply of fuel to the engine and thereby the air-fuel ratio in the combustion chamber (41). The muffler (13) suitably is provided with a catalytic element (140), preferably a three-way catalyst. The engine (1) preferably is a stratified charge engine.

Electronic fuel injection control system for an internal combustion engine, the internal combustion engine being equipped with at least one fuel feeding line provided with a fuel tank, at least one throttle valve, at least one injector, at least one fuel pump, at least one fuel return line having at least one solenoid valve, at least one first fuel return duct that connects the injector to the solenoid valve, at least one overpressure valve, at least one second return conduit adapted to connect the overpressure valve and the solenoid valve with the tank, wherein the fuel return line is provided with at least one calibrator allowing at least the state of said fuel pump and relative performances thereof to be verified.

A method of raising exhaust gas temperatures of a two-cycle uniflow scavenged engine at lower loads. At lower loads, the exhaust valves are activated with a frequency that is less frequent than every engine cycle. This exhaust valve deactivation may be combined with additional engine operating strategies, such as by using fewer than all cylinders as combusting cylinders, adjusting fueling to combusting cylinders, and reducing compressor output.

A method for operating the two stroke engine provides that the fuel valve is controlled after the starting process in at least a quasi-steady state such that, on the basis of uninterruptedly successive blocks of successive revolutions of the crankshaft, the fuel valve is opened and closed exactly once within each block. Each block includes from two to twenty revolutions of the crankshaft. The fuel valve is opened over a crankshaft angle (α) of more than 360° within one block in at least one operating state. A control device is provided for controlling the fuel valve. A quasi-steady state of the two stroke engine is a state in which the throttle element is adjusted by less than 10% of the maximum adjustment of the throttle element over a crankshaft angle (α) of 360°.