Process for managing the re-start of an internal combustion engine in a start and stop system

1. A process for managing a re-start of an internal combustion engine in a Start and Stop system using an electric motor acting on a crankshaft of the internal combustion engine and managed by an electric motor control unit (EMU), a first step of direct evaluation of the rotation regime of the crankshaft being provided through a rpm sensor directly placed on the crankshaft and connected to a combustion engine control unit (ECU) of the internal combustion engine: if the rotation regime is above a predetermined threshold, in case of re-opening of the throttle valve a control unit of the combustion engine (ECU) continues to provide fuel and ignition to the engine; if the rotation regime is below said predetermined threshold a crankshaft positioning step and an ignition step are provided, activated after a starting command, said predetermined threshold corresponding to a signal accuracy loss of said rpm sensor, wherein said crankshaft positioning step by the electric motor control unit (EMU) comprises:

a forward crankshaft rotation by a predetermined forward rotation angle;

a detection of a possible piston stall state followed, in negative case, by an additional forward crankshaft rotation until reaching a maximum predetermined forward rotation angle;

an inverse crankshaft rotation by a predetermined angle; and

a detection of a possible piston stall state followed, in negative case, by an additional inverse crankshaft rotation until reaching a maximum predetermined inverse rotation angle.

2. The process according to claim 1 , wherein said predetermined threshold does not exceed 150 rpm.

3. The process according to claim 1 , wherein said piston stall state is detected by a control unit of the engine (EMU) which receives data related to a current supply to the electric motor by an electric sensor.

4. The process according to claim 1 , wherein said piston stall state is detected by a control unit of the engine (EMU) which receives a piece of information related to a number of phase pulses detected by phase sensors of a stator of the electric motor.

5. The process according to claim 1 , wherein a stator of the electric motor is equipped with a sensor providing a signal representing a rotation direction of a rotor with respect to the stator which is sent to a control unit of the internal combustion engine (ECU) regulating fuel supply and ignition of the internal combustion engine.

6. The process according to claim 1 , wherein said predetermined forward rotation angle of said first forward rotation is comprised between 350° and 700°.

7. The process according to claim 4 , wherein said forward rotation maximum angle is determined by a number N of phase pulses detected by said phase sensors.

8. The process according to claim 1 , wherein said predetermined inverse rotation angle of said first forward rotation is comprised between 350° and 700°.

9. The process according to claim 4 , wherein said inverse rotation maximum angle is determined by a number M of phase pulses detected by said phase sensors.

10. The process according to claim 1 , further comprising an ignition step providing a forward crankshaft rotation to determine the starting of the internal combustion engine.

11. The process according to claim 10 , wherein, if the starting has not been implemented, the positioning procedure is repeated only by the inverse crankshaft rotation for the positioning step until ignition or execution of a predetermined number X of attempts, at the end thereof the system will signal a failure situation.