Systems and methods for operating an internal combustion engine that may be automatically stopped and started are described. In one example, an engine is rotated in a reverse direction after an engine stop so that a belt integrated starter/generator may rotate the engine in a forward direction and utilize the inertia of the engine to rotate trough top-dead-center compression stroke, thereby starting the engine.

An engine-generator starting apparatus a three-phase winding equipped with a generating unit that rotates relative to rotation of a crankshaft of an engine, and an electronic control unit that controls supply of electric current the three-phase winding to rotate the crankshaft and start the engine. In the apparatus, the electronic control unit controls to supply first current to the three-phase winding to make the engine crankshaft of rotate reverse, the first current is of a level for stopping the piston connected to the crankshaft at a position in a compression stroke. Then it controls to supply second current (that is greater than the first current) to the three-phase winding to make the crankshaft of the engine rotate forward when a predetermined time period has elapsed, and control to ignite fuel supplied to the engine after the second current is supplied to the three-phase winding.

Systems and methods for operating an internal combustion engine that may be automatically stopped and started are described. In one example, an engine is rotated in a reverse direction after an engine stop so that a belt integrated starter/generator may rotate the engine in a forward direction and utilize the inertia of the engine to rotate trough top-dead-center compression stroke, thereby starting the engine.

An engine start control device includes an pass determination section that performs a pass determination process of determining, based on a rotation state of the engine output shaft, whether a piston in a cylinder of the engine can pass over a compression top dead center for a rotation drop period in response to an occurrence of the start request. The engine start control device also includes a start control section that when it is determined that the piston cannot pass over the compression top dead center, starts driving of the motor in a low reaction force period to start the engine, the low reaction force period being a period in which a reaction force applied to the piston by a cylinder internal pressure in the cylinder is a predetermined value or less.

An engine control apparatus determines that a piston is at a compression top dead center immediately before engine speed of an engine becomes zero if of the engine speed at the compression top dead center of the engine in a rotation drop period while the engine speed drops to zero after combustion of the engine is stopped. In the case where it is determined that the piston is at the compression top dead center immediately before the engine speed of the engine becomes zero, the engine control apparatus applies counter torque by the rotating electrical machine from the compression top dead center to stop the piston at a rotation angle position in a first half period of expansion process by application of the counter torque.

Methods and systems are provided for improving starting of an engine that has been stopped during humid ambient conditions. The methods and systems may reduce the possibility of starting an engine having liquid water in engine cylinders to improve engine starting. In one example, a laser is applied to a metal surface within the engine to vaporize water that may be in the engine due to condensation.

A method for controlling a mild hybrid vehicle is disclosed. The method includes determining, by a controller, whether a state of charge (SOC) of a first battery that supplies electric power to a starter-generator exceeds a reference value. The method further includes operating, by the controller, the starter-generator and a starter that is separate from the starter-generator and receives electric power from a second battery at a voltage lower than that of the first battery. A combustion engine of the mild hybrid vehicle is started using the starter-generator and the starter when it is determined that the state of charge of the first battery exceeds the reference value and it is determined that an ambient air temperature of the engine exceeds a temperature reference value.

An internal combustion engine start assist mechanism includes an elastic member attached to between a first support portion of a starting apparatus side member and a second support portion of an internal combustion engine side member along an internal combustion engine rotation direction, a stopper portion of the internal combustion engine side member, and a contact portion of the starting apparatus side member disposed behind the stopper portion. The contact portion forms a gap relative to the stopper portion when the starting apparatus side member rotates in a direction opposite to the internal combustion engine rotation direction. When the starting apparatus side member rotates in the internal combustion engine rotation direction after the opposite rotation, a combination of the rotation of the starting apparatus side member with rotation caused by the elastic member causes the starting apparatus side member to rotate integrally with the internal combustion engine side member.

An engine start control device that is capable of winding back a crankshaft more quickly at the time of an idling stop includes a swingback controller for performing a swingback control process for reversing a crankshaft when an engine is started by operating a starter switch, a windback reverse controller for performing a windback control process for reversing the crankshaft immediately after the engine is stopped by the idling stop control process, and a motor brake controller for performing a motor brake control process for braking the crankshaft reversed by the windback control process by rotating the crankshaft in the normal direction after the windback control process performed by the windback reverse controller. The value of a motor current supplied at the time the crankshaft is reversed by the windback reverse controller is set as a value equal to or larger than the value of a motor current supplied at the time the crankshaft is reversed by the swingback controller.

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.