A supercharging device for an engine includes an electric supercharger which supercharges intake air, an intercooler which cools intake air discharged from the electric supercharger; and an intake manifold which is disposed substantially horizontally, and is configured to communicate between a downstream end of the intercooler in an intake air flow direction, and intake ports. The downstream end of the intercooler is located on a lower end of the intercooler. The downstream end of the intercooler is disposed substantially at the same height as an upstream end of the intake ports. The electric supercharger is disposed below the intercooler along a surface of the engine on an intake side where the intake ports are opened.

It is common for crankshafts of internal combustion engines to have main bearing journals provided between each of the conrod bearing journals. However, to reduce engine friction, the fewest main bearing journals that can be used while still meeting the design targets is preferred. A crankshaft for an in-line, four-cylinder engine, according to an embodiment of the disclosure, has three main bearing journals. Bridges, one each located between first and second conrod bearing journals and between third and fourth conrod bearing journals. The bridges have a cross-section with at least two concavities to improve the strength of the bridge compared to, for example, a cylindrical bridge, without greatly increasing the mass of material used in the bridge. Furthermore, a locus of a centroid of cross sections through the bridge are not coincident with an axis of rotation of the crankshaft, but instead is displaced toward the nearer conrod bearing journal.

A rotational combustion engine that generates force from the reciprocal motion and centripetal motion of one or more pistons that is then converted into rotational motion of a first cam and second cam wherein the cams are separated by a 2-3 degree horizontal offset and an angle of 60 degrees as well as camshaft assembly and driving shaft to provide power to an entity such as an automobile.

Internal combustion engine having cam actuated valves that can be controlled to facilitate the use of different air charge levels in different cylinders or sets of cylinders are described. In one aspect a first set of cylinders is operated in a skip fire manner in which the corresponding cylinders are deactivated during skipped working cycles. Cam actuated intake valves associated with a second set of cylinders are operated differently so that the air charge in the cylinders in the second set is different than the air charge in fired cylinders subject to the skip fire control. According to another aspect, an engine having cam actuated intake valves is operated in a dynamic firing level modulation mode. During the dynamic firing level modulation operation, the cam actuated intake valves are controlled in at least two different manners to such that different cylinder working cycles have different air charges.

Embodiments for operating an engine having parallel turbochargers and two fluidically coupleable, separated intake manifolds is provided. In one example, a method includes responsive to a first condition, operating a first cylinder group of an engine, deactivating a second cylinder group of the engine, and blocking fluidic communication between a first intake manifold coupled to the first cylinder group and a second intake manifold coupled to the second cylinder group, and responsive to a second condition, activating the second cylinder group and establishing fluidic communication between the first and second intake manifolds.

Disclosed herein is an exhaust insulator structure for a multi-cylinder engine of a vehicle. The structure includes an exhaust manifold, an exhaust gas purifier, and a heat insulator. The engine is able to switch its mode of operation from an all-cylinder operation in which all of four cylinders thereof are activated to a cylinder-cutoff operation in which two of the four cylinders are deactivated to serve as idle cylinders and the other two cylinders are activated to serve as active cylinders, or vice versa. The exhaust manifold includes: idle-cylinder-connected branched exhaust piping communicating with the idle cylinders; and active-cylinder-connected branched exhaust piping communicating with the active cylinders. A portion of the heat insulator facing the active-cylinder-connected branched exhaust piping has an opening that lets air blowing against the vehicle traveling into the heat insulator.

A multi-cylinder engine exhaust structure disclosed herein includes: four branched exhaust pipes respectively communicating with four cylinders classified into two groups, each being comprised of two of the four cylinders with discontinuous exhaust strokes; two intermediate collecting pipes, each being formed by combining associated two of the four branched exhaust pipes respectively communicating with the two cylinders in an associated one of the two groups; a last collecting pipe formed by combining these intermediate collecting pipes; and an exhaust gas purifier coupled to an exhaust gas downstream end of the last collecting pipe. Two of the four branched exhaust pipes respectively communicating with two of the four cylinders to be activated as two active cylinders while the engine is performing a cylinder-cutoff operation are shorter than the two other branched exhaust pipes respectively communicating with the two other cylinders to be deactivated as two idle cylinders during the cylinder-cutoff operation.

An internal combustion engine has at least one cylinder wall forming a cylinder, and at least one knock sensor held on a housing element. The knock sensor is fixed to a fastening point of the housing element. An intermediate chamber is provided in the radial direction of the cylinder between at least one section of the cylinder wall and the fastening point of the housing element arranged on a side of the cylinder wall facing away from the cylinder, a distance extending at least in the radial direction of the cylinder being provided as a result. At least one sound transmission bridge extends in the intermediate chamber, bridging the distance from the cylinder wall continuously to the fastening point, via which vibrations, on the basis of which knocking combustion can be detected by the knock sensor, are transferrable from the cylinder wall to the fastening point.

Methods and systems are provided for a valve system for actuating two cylinder valves in an engine. In one example, the valve system may include a single pump and a solenoid valve capable of non-concurrently actuating the two cylinder valves coupled to separate cylinders.

An exhaust gas recirculation system for a multi-cylinder engine is provided, which includes an exhaust manifold connected to a cylinder head, a catalyst connected to a downstream end of the exhaust manifold in terms of an exhaust gas flow, an EGR gas outlet provided downstream of the catalyst, an in-head EGR passage penetrating the cylinder head, and an EGR pipe extending from the EGR gas outlet and directly connected to an inlet of the in-head EGR passage to lead EGR gas thereto. The catalyst is disposed so that the exhaust gas flows therein from a first side to a second side in an engine cylinder lined-up direction. The EGR gas outlet is located on the second side with respect to the center of the engine in the cylinder lined-up direction, and the inlet of the in-head EGR passage is located in the first side with respect to the engine center.