An internal combustion engine is provided. The internal combustion engine includes a supercharger that is arranged in an intake passage; an intercooler that is arranged downstream of the supercharger in a direction of intake air flow, in the intake passage; and a blow-by gas returning apparatus. The blow-by gas returning apparatus includes a bypass passage, an ejector, and a blow-by gas passage. The bypass passage connects a first position that is arranged between the supercharger and the intercooler, and a second position that is arranged downstream of the intercooler of the intake passage together. The ejector is arranged in the bypass passage, and configured to draw in blow-by gas from the crankcase through the blow-by gas passage when air flows through the bypass passage from the first position toward the second position.

An internal combustion engine is provided. The internal combustion engine includes a supercharger that is arranged in an intake passage; an intercooler that is arranged downstream of the supercharger in a direction of intake air flow, in the intake passage; and a blow-by gas returning apparatus. The blow-by gas returning apparatus includes a bypass passage, an ejector, and a blow-by gas passage. The bypass passage connects a first position that is arranged between the supercharger and the intercooler, and a second position that is arranged downstream of the intercooler of the intake passage together. The ejector is arranged in the bypass passage, and configured to draw in blow-by gas from the crankcase through the blow-by gas passage when air flows through the bypass passage from the first position toward the second position.

An electronic injection two-stroke endothermic engine comprising an upper fuel injector (13) and a lower fuel injector (14), both accommodated in an intake duct (12) directly facing the cylinder (1), the latter closed by a head to form a combustion chamber (6) with one or more spark plugs (5) and connected to a pump-crankcase underneath via a plurality of side transfer ports (7, 8) which a central transfer port (15) is added to and crosses said intake duct (12) and allows the fuel sprayed by said lower injector (14) to reach the inside of the cylinder (1).

An ignition system for an internal combustion engine has a power source, a transformer having first and second primary windings and a secondary winding, a connector extending from the secondary winding and adapted so as to connect with a terminal of the spark plug of the internal combustion engine, and electronic spark timing circuit cooperative with the transformer so as to activate and deactivate voltage to the first and second primary windings. The first and second primary windings are connected to the power source such that the transformer produces an alternating voltage output from the secondary winding of between 1 kHz and 100 kHz and a voltage of at least 20 kV. A forced push-pull inverter is cooperative with the electronic spark timing circuit so as to fix a frequency of voltage to the first and second primary windings.

An exhaust system for a lean-burn internal combustion engine is described, and includes an injection system for injecting reductant into an exhaust gas feedstream upstream of a selective catalytic reduction device (SCR). A control method for controlling the injection system includes determining an upstream NOx gas concentration upstream of the SCR device, determining a measured downstream NOx gas concentration based upon a signal output from a sensor configured to monitor NOx gas concentration downstream of the SCR device, and determining an estimated downstream NOx gas concentration based upon an executable model. A first correlation between the upstream NOx gas concentration and the measured downstream NOx gas concentration is determined, and a second correlation between the upstream NOx gas concentration and the estimated downstream NOx gas concentration is determined. The reductant injection is controlled based upon the first and second correlations.

An exhaust system for a lean-burn internal combustion engine is described, and includes an injection system for injecting reductant into an exhaust gas feedstream upstream of a selective catalytic reduction device (SCR). A control method for controlling the injection system includes determining an upstream NOx gas concentration upstream of the SCR device, determining a measured downstream NOx gas concentration based upon a signal output from a sensor configured to monitor NOx gas concentration downstream of the SCR device, and determining an estimated downstream NOx gas concentration based upon an executable model. A first correlation between the upstream NOx gas concentration and the measured downstream NOx gas concentration is determined, and a second correlation between the upstream NOx gas concentration and the estimated downstream NOx gas concentration is determined. The reductant injection is controlled based upon the first and second correlations.

A method for operating an internal-combustion engine includes increasing a torque demand, controlling a throttle valve, opening an air injection valve and continuously measuring first and second gas pressures with an electronic control unit. The method also includes closing the throttle valve, measuring a first gas mass flow, retarding an ignition angle, and closing the air injection valve. In the method the throttle valve is opened with the control unit when the first gas pressure p.sub.1 equals the second gas pressure p.sub.2. The method also includes continuously controlling the fuel system with the electronic control unit to have a stoichiometric fuel/air ratio of the internal combustion engine being constantly combusting in the internal combustion engine.

A method for operating an internal-combustion engine includes increasing a torque demand, controlling a throttle valve, opening an air injection valve and continuously measuring first and second gas pressures with an electronic control unit. The method also includes closing the throttle valve, measuring a first gas mass flow, retarding an ignition angle, and closing the air injection valve. In the method the throttle valve is opened with the control unit when the first gas pressure p.sub.1 equals the second gas pressure p.sub.2. The method also includes continuously controlling the fuel system with the electronic control unit to have a stoichiometric fuel/air ratio of the internal combustion engine being constantly combusting in the internal combustion engine.

Injection of the fuel by the injector 43 creates a gas flow in the combustion chamber. The gas expands in a radial fashion from an axis of a cylinder toward a radial outside of the cylinder, and then flows from the radial outside along the cylinder head bottom face 221 toward the axis of the cylinder. The spark plug 41 has a gap positioned away from the axis of the cylinder toward the radial outside of the cylinder at a predetermined distance, and placed radially inwardly from a position opposite a rim of an opening of the cavity 242. A side electrode extends to be oriented in a direction perpendicular to the flow of the gas along the cylinder head bottom face. The gap has a center positioned near the cylinder head bottom face, and closer to an interior of a combustion chamber than to the cylinder head bottom face.

An exhaust system for a lean-burn internal combustion engine is described, and includes an injection system for injecting reductant into an exhaust gas feedstream upstream of a selective catalytic reduction device (SCR). A control method for controlling the injection system includes determining an upstream NOx gas concentration upstream of the SCR device, determining a measured downstream NOx gas concentration based upon a signal output from a sensor configured to monitor NOx gas concentration downstream of the SCR device, and determining an estimated downstream NOx gas concentration based upon an executable model. A first correlation between the upstream NOx gas concentration and the measured downstream NOx gas concentration is determined, and a second correlation between the upstream NOx gas concentration and the estimated downstream NOx gas concentration is determined. The reductant injection is controlled based upon the first and second correlations.