This method includes the following steps: determining the angular position and the rotational speed for a first point of measurement and a second point of measurement of a engine position sensor, determining at least one gradient of the rotational speed different from the speed gradient between the two points of measurement of the previous step, approximating the actual rotational speed curve with respect to the angular position with a polynomial function of degree two, and carrying out a calculation, in advance, for determining an estimated rotational speed at the predefined position, the position defining a future angular position of the crankshaft, by applying the polynomial function to the predefined future position. The method can be used to predict engine rotation reversal.

In a system for controlling rotation of torque applied to a rotating shaft of an engine of a vehicle that uses the engine as a drive source thereof, a motor is provided. A main controller controls the engine and the motor. The main controller selectably activates the motor that applies first torque to the rotating shaft of the engine, and deactivates the motor. A rotary electric machine includes a rotor connected to the rotating shaft of the engine. A rotation parameter detector measures a rotation parameter associated with rotation of the rotor of the rotary electric machine. A sequence controller performs, in response to an occurrence of a trigger situation, a control sequence that controls, independently of the main controller, the rotary electric machine based on the rotation parameter measured by the rotation parameter detector, thus applying second torque to the rotating shaft of the engine.

A starting control device for an engine includes an ECU configured to: i) execute an autonomous starting control in which the ECU injects fuel into the cylinder from a fuel injection valve after a crank shaft rotates reversely before the crank shaft stops its rotation and then ignites an air-fuel mixture using an ignition plug to start the engine without using a starter motor; ii) determine whether a pressure in the cylinder increasing due to the reverse rotation is equal to or greater than a predetermined pressure at a time point of firing of the air-fuel mixture by the ignition; and iii) prohibit starting of the engine under the autonomous starting control when the ECU determines that the pressure in the cylinder is not equal to or greater than the predetermined pressure.

In the cases where a reverse operation of a crankshaft is performed after fuel injection and ignition in a cylinder in a power stroke and it is determined that an engine start is failed, a starter motor is operated, and fuel injection and ignition are executed in the cylinder in the compression stroke to start an engine.

A start control system for an engine is provided. The engine is a direct injection engine, and the engine is provided with a starter motor. The start control system includes an electronic control unit. The electronic control unit is configured to execute fuel injection and ignition in a cylinder in an expansion stroke so as to start the engine without using the starter motor, when the electronic control unit determines that a restart condition of the engine is satisfied immediately before the engine is stopped. The electronic control unit is configured to control an ignition delay time based on at least one of a rotational direction and a rotational speed of a crankshaft, during execution of the fuel injection. The ignition delay time is a period of time from fuel injection into the cylinder in the expansion stroke to ignition.

A process for starting an internal combustion engine, providing the use of an electric motor acting on the driveshaft of the internal combustion engine, provides a positioning step, activated upon switching-off the engine, and a switching-on step, activated after a starting control, wherein said positioning step comprises: a forward rotation by a predetermined forward rotation angle; a detection of a possible stall state followed, in negative case, by an additional forward rotation until reaching a predetermined maximum forward rotation angle; an inverse rotation by a predetermined angle; and a detection of a possible stall state followed, in negative case, by an additional inverse rotation until reaching a predetermined maximum inverse rotation angle

An electric motor for starting internal combustion engines and a relative starting control system of such engine comprising said electric motor of the type with permanent magnets allows a more effective and simpler management of the internal combustion engine thereto the electric motor is connected, wherein a monitoring unit of the electric motor (EMU) and a monitoring unit of the internal combustion engine (ECU) are provided, wherein the electric motor comprises a direction sensor (18) providing a signal representing the rotation direction of the rotor (12) of the electric motor, which is connected to said monitoring unit of the internal combustion engine (ECU).

A vehicle has a frame, a front suspension assembly, a pair of skis, an endless drive track, and an internal combustion engine. The engine has: a motor-generator having a rotor and a stator, the motor-generator being operable in motor mode and in generator mode; a recoil starter operable to rotate a crankshaft of the engine via the rotor in a same direction as does the motor-generator in generator mode; at least one sensor adapted for sensing at least one engine parameter; and an engine control unit (ECU) receiving a signal from the at least one sensor, the ECU controlling a rotation of the crankshaft by one of the motor-generator and the recoil starter based on the signal.