Systems and methods for stopping and starting a direct injection engine are described. In one example, the air is injected into one or more pre-chambers of engine cylinders to adjust engine pumping torque during an engine stop so that the engine may stop at a crankshaft position that facilitates direct engine starting.

A starting control device for an internal combustion engine is provided with a hard cranking device and a soft cranking device that are respectively capable of and incapable of cranking the internal combustion engine to a target idle rotation speed. The starting control device includes: a starting mode determination unit determining whether to carry out starting in a non-combustion pressure mode whereby starting is carried out with the hard cranking device, or in a combustion pressure combination mode whereby starting is carried out through cranking with the soft cranking device while using a combustion pressure generated by supplying fuel to the internal combustion engine in combination; and an intake air amount control unit making an amount of intake air during cranking differ between a case where starting is carried out in the non-combustion pressure mode and a case where starting is carried out in the combustion pressure combination mode.

A control device according to the present invention performs an automatic stop control in which an injection of fuel from a fuel injection valve is stopped and a rotation of an engine is stopped when an automatic stop condition is satisfied. Furthermore, the control device controls an injection operation of fuel and an ignition operation to the fuel in consideration of compression when the fuel is actually ignited in an expansion stroke cylinder, when a re-start demand occurs after an initiation of the automatic stop control and the engine is to be re-started by an ignition start-up. Specifically, the control device predicts a crank angle at an actual ignition time point in a case where processing for performing the ignition start-up at the present time whenever a predetermined time period has passed. Then, the control device initiates the ignition start-up when the crank angle falls within a predetermined range in which a sufficient compression can be attained. Thereby, the engine is more certainly re-started by the ignition start-up.

The invention relates to a method for starting operation of an internal combustion engine, wherein the method comprises the steps of: when the internal combustion engine is not operating, providing pressurized gas in the air intake duct; opening the intake valve in a first cylinder while keeping the exhaust valve of the first cylinder closed so as to allow the pressurized gas to enter the first cylinder, press onto the corresponding piston and thereby move the corresponding piston and rotate the crank shaft; supplying fuel to at least one of the cylinders where the corresponding piston has performed or is performing a compression step so as to ignite the fuel and start operation of the engine.

Systems and methods for stopping and starting a direct injection engine are described. In one example, the air is injected into one or more pre-chambers of engine cylinders to adjust engine pumping torque during an engine stop so that the engine may stop at a crankshaft position that facilitates direct engine starting.

An engine control device for a saddle riding vehicle includes a mechanical centrifugal clutch for connecting and disconnecting driving force from an engine to a driving wheel, a throttle operator to adjust output power of the engine, a motor to rotate a crankshaft of the engine, and a control unit to control the motor and a fuel injection system. The control unit executes injection stopping control for stopping fuel injection during deceleration of the vehicle and executes, when an opening operation of the throttle operator is performed after an engine speed becomes equal to or lower than a centrifugal clutch disconnection speed at which the centrifugal clutch is disconnected, acceleration assist control for rotating the crankshaft with the motor.

A method for starting an internal combustion engine of a motor vehicle includes detecting before a direct starting of the internal combustion engine that a piston which is disposed translationally moveably in a start cylinder of the internal combustion engine is in an upper half of, or in a middle of, a stroke of the piston. In response to the detecting, rotating an output shaft of the internal combustion engine in a direction of rotation of the output shaft such that the piston is in a lower half of the stroke of the piston and in an intermediate position. The method further includes rotating the output shaft in a second direction of rotation before and/or during fuel being first directly injected into the start cylinder such that the piston is moved out of the intermediate position in a direction of an upper dead center of the piston.

A controller executes a first restarting process when restarting of an engine is requested under a condition where an engine speed is less than a determination speed. In the first restarting process, cranking of the engine is performed by a motor generator in a state in which the motor generator is connected to a crankshaft through engagement of a clutch, and fuel injection and ignition are initiated in the engine when a combustion initiation condition is satisfied in this state. The controller executes a second restarting process when restarting of the engine is requested under a condition where the engine speed is greater than or equal to the determination speed. In the second restarting process, fuel injection and ignition are initiated in the engine, and the motor generator is connected to the crankshaft through engagement of the clutch after the engine has been restarted.

Systems and methods for starting and operating a direct injection engine are described. In one example, the air and fuel are injected into a pre-chamber of a cylinder of an engine while the engine is not rotating. The air and fuel are combusted in the pre-chamber to improve ignition of an air and fuel mixture in the cylinder.

Methods and systems are provided for performing expansion combustion in an engine of a start-stop vehicle. In one example, a method may include, responsive to receiving an auto-start request to restart an engine from an auto-stop, determining a fuel mass to inject into a cylinder for an expansion combustion event based on a duration of the auto-stop, and actuating a spark plug of the cylinder after injecting the determined fuel mass to perform the expansion combustion event. In this way, an air-fuel ratio of the expansion combustion event may be more accurately controlled, resulting in more robust expansion combustion engine restarts.