In a control method of an internal combustion engine including a fuel injection valve having a plurality of injection holes and adapted to directly inject a fuel into a cylinder and an ignition plug adapted to generate a plug discharging channel, after fuel injection is performed, spark ignition is performed while turbulence in an air flow is generated by the fuel injection by an ignition plug disposed so that a discharging region is sandwiched by fuel sprays injected from the two adjacent injection holes and located within a range where the turbulence in the air flow is generated.

Intake holes at the opposite ends are opened and closed by first intake valves. The middle intake hole is opened and closed by a second intake valve. A control device includes an intake variable valve device. First branch channels are connected to the intake holes and produce a normal tumble flow. A second branch channel is configured such that the flow rate of intake air passing through the middle intake hole is relatively greater on the side closer to the outer periphery of the combustion chamber. Where increasing the flow coefficient is given a higher priority, a three-valve drive mode is selected. Where the strength of the normal tumble flow is enhanced, a two-valve drive mode is selected. Where production of the normal tumble flow is reduced, a one-valve drive mode is selected.

An ECM determines a failure exist and a failure site in a control valve device from first and second failure diagnoses. In the first failure diagnosis, a failure is determined to have occurred if an opening amount that represents an absolute value of a difference between a detected opening amount and a target opening amount of a valve body is greater than a preset threshold when the target opening amount of the valve body is constant for a predetermined time. In the second failure diagnosis, a failure is determined to have occurred if an opening amount that represents the absolute value of the difference between the opening amount of the valve body when fully open or fully closed and the detected opening amount is greater than the preset threshold when a portion rotating integrally with the valve body has been pressed against a stopper continuously for a predetermined time.

An internal combustion engine includes an intake port configured to generate a swirl in a cylinder, an exhaust port, and a piston. The piston includes a top surface provided in an upper portion of the piston, a cavity provided from the top surface toward a lower portion of the piston around a central axis of the piston, and a connection surface connecting an inner edge of the top surface and an upper end of a side surface of the cavity to each other. The connection surface is provided to be closer to a lower portion side of the piston than the top surface. An area of the connection surface projected on a plane parallel to the top surface is larger on an intake port side than on an exhaust port side.

Methods and systems are provided for forming an air-fuel mixture in a combustion chamber of an internal combustion engine. In one example, a system may include an adjustable intake line coupled to an inlet opening of the cylinder. The system may adjust turbulence formed in the cylinder in response to engine operating conditions by controlling a pivoting angle between a first section of the intake line and a second section of the intake line.

A valve body unit (11) in which a plurality of valve bodies (17) which open and close intake passages (10) are attached on a rotational shaft (16) is inserted into inner sides of housing passages (28) of a housing (12) and, thereafter, a holder (13) is mounted in the housing (12) to rotatably support the valve body unit (11). A flange (14) is fixed onto an upper surface of the housing (12) on the holder (13) by means of a vibration welding and the holder (13) is retained with this flange (14) and the housing (12).

An intake manifold for an internal combustion engine includes branch pipes, each of which is connected to one of intake ports and has an intake passage, valve cases, each of which is provided to one of the branch pipes and connected to the corresponding intake port, branch pipe bodies, each of which is connected to the upstream end of one of the valve cases, valves, each of which is provided in one of the valve cases to change the cross-sectional area of the intake passage of the corresponding branch pipe, and a coupling portion, which is located between downstream ends of each adjacent pair of the branch pipe bodies to couple the downstream ends to each other.

Provided is an internal combustion engine including a sparkplug disposed in the vicinity of the center portion of an upper wall surface of a combustion chamber. Tumble flow generated during lean burn operation is controlled such that the tumble flow shape changes according to the engine rotation speed between a first tumble shape (usual tumble shape) in which the flow direction of a gas around the sparkplug at the time of ignition is direction from an intake valve side toward an exhaust valve side in a latter half of a compression stroke, and a second tumble shape ( tumble shape) in which the flow direction of the gas is reversed in the latter half of the compression stroke from the direction from the intake valve side toward the exhaust valve side to the direction from the exhaust valve side toward the intake valve side.

Provided is a control device of an engine that can certainly suppress and avoid pre-ignition. A control device of an engine is an engine control device for controlling the behavior of fuel that is directly injected into a combustion chamber of a cylinder by a tumble flow, and it has an injector that directly injects the fuel into the combustion chamber, an intake port that generates the tumble flow in the combustion chamber, and an ECU that injects the fuel from the injector at a plurality of injection timings including an intake-stroke-early-half injection timing that is set at an early half of the intake stroke of the cylinder, when an operating state of the engine is in a high-load, low-rotation range.

A structure of an air flow control valve includes: valve main body portions respectively provided in intake ports, and controlling the flow of a fluid supplied to combustion chambers of an internal combustion engine; connecting shafts provided integrally with the valve main body portions, and connecting the valve main body portions; a first bearing member formed of a single member having a first bearing hole turnably supporting the connecting shaft at a first end; and a second bearing member provided separately from the first bearing member, and formed of a single member having a second bearing hole turnably supporting the connecting shaft at a second end. The connecting shafts are formed integrally with the valve main body portions in a state where the first and second bearing members are respectively fitted onto the connecting shafts connecting the valve main body portions.