Method to control the sealing of a blow-by gas breather circuit of an internal combustion engine

1. A method to control the sealing of a blow-by breather circuit ( 15 ) containing suspended lubricating oil and particulate in an internal combustion engine ( 1 ); the internal combustion engine ( 1 ) comprises a head defining a number of cylinders ( 2 ), which are connected to an intake manifold ( 3 ) that receives fresh air, namely air coming from the outside, through an intake pipe ( 6 ), and further defining a crankcase and a pan which is designed to collect the lubricating oil, closing said crankcase on the lower side; the internal combustion engine ( 1 ) further comprises a blow-by gas breather circuit ( 15 ) provided, in turn, with a separator device ( 16 ) to agglomerate finely atomized lubricating oil particles and to remove solid particulate particles, having an inlet which is connected through a first pipe ( 18 ) to the crankcase, from which it receives blow-by gas containing suspended lubricating oil and particulate, an outlet, which is connected through a second pipe ( 19 ) to the intake pipe ( 6 ) and through which the gas purified from the lubricating oil and the particulate flows out, and a draining outlet, which is connected through a third pipe ( 20 ) to a lower portion of the crankcase to which it feeds the agglomerated lubricating oil and particulate; the blow-by breather circuit ( 15 ) further comprising a pressure sensor ( 26 ); the method comprising the following steps:

acquiring the signal (S) coming from said pressure sensor ( 26 );

processing the signal (S) coming from said pressure sensor ( 26 ), comprising the following sub-steps:

filtering the signal (S) coming from said pressure sensor ( 26 ); and

integrating over time the square of the filtered signal (S f ) coming from the pressure sensor ( 26 ), wherein the integrated signal (S int ) represents the combustion energy generated by the internal combustion engine ( 1 ); and

determining the sealing of the second pipe ( 19 ) of the breather circuit ( 15 ) as a function of the integrated signal (S int ) representing the combustion energy generated by the internal combustion engine ( 1 ).

2. A method according to claim 1 , further comprising the following steps:

determining an expected value (E) of the combustion energy generated by the internal combustion engine ( 1 );

comparing the expected value (E) of the combustion energy generated by the internal combustion engine ( 1 ) with the integrated signal (S int ) representing the combustion energy generated by the internal combustion engine ( 1 ); and

determining the sealing of the second pipe ( 19 ) of the breather circuit ( 15 ) as a function of the comparison between the integrated signal (S int ) representing the combustion energy generated by the internal combustion engine ( 1 ) and the expected value (E) of the combustion energy generated by the internal combustion engine ( 1 ).

3. A method according to claim 2 , further comprising the following steps:

determining a threshold value (TV);

calculating the difference between the expected value (E) of the combustion energy generated by the internal combustion engine ( 1 ) and the integrated signal (S int ) representing the combustion energy generated by the internal combustion engine ( 1 ); and

determining the sealing of the second pipe ( 19 ) of the breather circuit ( 15 ) as a function of the comparison between the threshold value (TV) and the difference between the expected value (E) of the combustion energy generated by the internal combustion engine ( 1 ) and the integrated signal (S int ) representing the combustion energy generated by the internal combustion engine ( 1 ).

4. A method according to claim 3 , comprising the further step of determining a disconnection of the second pipe ( 19 ) of the breather circuit ( 15 ), in case the difference between the expected value (E) of the combustion energy generated by the internal combustion engine ( 1 ) and the integrated signal (S int ) representing the combustion energy generated by the internal combustion engine ( 1 ) exceeds the threshold value (TV).

5. A method according to claim 3 , comprising the further step of determining the perfect sealing of the second pipe ( 19 ) of the breather circuit ( 15 ), in case the difference between the expected value (E) of the combustion energy generated by the internal combustion engine ( 1 ) and the integrated signal (S int ) representing the combustion energy generated by the internal combustion engine ( 1 ) is lower than or equal to the threshold value (TV).

6. A method according to claim 1 , wherein the pressure sensor ( 26 ) detects the pressure in a position close to and facing the point where the second pipe ( 19 ) of the breather circuit ( 15 ) leads into the intake pipe ( 6 ).

7. A method according to claim 1 , wherein the sub-step of filtering the signal (S) coming from the pressure sensor ( 26 ) is performed by means of a second-order filter.

8. A method according to claim 1 , comprising a further step of determining the sealing of the second pipe ( 19 ) of the breather circuit ( 15 ) at each starting of the internal combustion engine ( 1 ).

9. A method according to claim 8 , further comprising the following steps:

determining a waiting time (WT); and

after having detected that the internal combustion engine ( 1 ) has been started, ignoring the signal (S) coming from the pressure sensor ( 26 ) for a time interval lasting as long as the waiting time (WT).

10. A method according to claim 9 , further comprising the followings steps:

determining an integration time (IT); and

after having detected that the internal combustion engine ( 1 ) has been started, integrating over time the square of the filtered signal (S f ) coming from the pressure sensor ( 26 ) for a time interval lasting as long as the integration time (IT).