Method to control the temperature of the exhaust gases of a supercharged internal combustion engine

Patent metadata

Field	Value
Publication number	US-9567886-B2
Application number	US-201514954219-A
Country	US
Kind code	B2
Filing date	Nov 30, 2015
Priority date	Dec 2, 2014
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

A method to control the temperature of the exhaust gases of a supercharged internal combustion engine, the method comprising: determining the minimum air/fuel ratio of the exhaust gases downstream of the exhaust manifold as a function of the flow rate of air that is not involved in the combustion taking place inside the cylinders and flows directly from the intake manifold into the exhaust pipe; detecting an air/fuel ratio of the exhaust gases downstream of the exhaust manifold by means of a sensor; and controlling the supercharged internal combustion engine as a function of the comparison between the air/fuel ratio of the exhaust gases detected by the sensor and/or the minimum air/fuel ratio of the exhaust gases with a number of threshold values.

First claim

The invention claimed is:

1. A method to control the temperature of the exhaust gases of a supercharged internal combustion engine ( 1 ) comprising a number of cylinders ( 3 ), an intake manifold ( 4 ), which is connected to the cylinders ( 3 ), an exhaust manifold ( 5 ), which is connected to the cylinders ( 3 ), as well, and feeds the exhaust gases produced by the combustion taking place inside the cylinders ( 3 ) to an exhaust system, and a turbocharger ( 12 ), which is provided with a turbine ( 13 ) and a supercharger ( 14 ); and a sensor ( 25 ), which measures the air/fuel ratio of the exhaust gases downstream of the exhaust manifold ( 5 ); the supercharged internal combustion engine ( 1 ), furthermore, is designed to permit the passage of air not involved in the combustion taking place inside the cylinders ( 3 ) from the intake manifold ( 4 ) directly into the exhaust pipe ( 10 ); the method comprises the steps of:
determining the flow rate (m air _ scav ) of air that is not involved in the combustion taking place inside the cylinders ( 3 ) and flows directly from the intake manifold ( 4 ) into the exhaust pipe ( 10 );
determining the minimum air/fuel ratio (λ min ) of the exhaust gases downstream of the exhaust manifold ( 5 ) as a function of the flow rate (m air _ scav ) of air that is not involved in the combustion taking place inside the cylinders ( 3 ) and flows directly from the intake manifold ( 4 ) into the exhaust pipe ( 10 );
detecting the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) provided by the sensor ( 25 );
comparing the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) and/or the minimum air/fuel ratio (λ min ) of the exhaust gases downstream of the exhaust manifold ( 5 ) with a number of threshold values (UTV OL _ SCAV , UTV INHIB _ SCAV , UTV LIMIT _ SCAV , LTV OL _ SCAV , LTV INHIB _ SCAV , LTV LIMIT _ SCAV , SV); and
controlling the supercharged internal combustion engine as a function of the comparison between the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) and/or the minimum air/fuel ratio (λ min ) of the exhaust gases downstream of the exhaust manifold ( 5 ) with said number of threshold values (UTV OL _ SCAV , UTV INHIB _ SCAV , UTV LIMIT _ SCAV , LTV OL _ SCAV , LTV INHIB _ SCAV , LTV LIMIT _ SCAV , SV).

2. A method according to claim 1 and comprising the further steps of:
comparing the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) with a first pair of threshold values (UTV LIMIT _ SCAV , LTV LIMIT _ SCAV ); and
limiting the flow rate (m air _ scav ) of air that is not involved in the combustion taking place inside the cylinders ( 3 ) and flows directly from the intake manifold ( 4 ) into the exhaust pipe ( 10 ), if the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) is not comprised within the interval defined by the first pair of threshold values (UTV LIMIT _ SCAV , LTV LIMIT _ SCAV ).

3. A method according to claim 1 and comprising the further steps of:
comparing the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) with a second pair of threshold values (UTV INHIB _ SCAV , LTV INHIB _ SCAV ); and
forbidding the passage of a flow rate (m air _ scav ) of air that is not involved in the combustion taking place inside the cylinders ( 3 ) directly from the intake manifold ( 4 ) into the exhaust pipe ( 10 ), if the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) is not comprised within the interval defined by the second pair of threshold values (UTV INHIB _ SCAV , LTV INHIB _ SCAV ).

4. A method according to claim 2 , wherein the interval defined by the first pair of threshold values (UTV LIMIT _ SCAV , LTV LIMIT _ SCAV ) is comprised within the interval defined by the second pair of threshold values (UTV INHIB _ SCAV , LTV INHIB _ SCAV ).

5. A method according to claim 1 and comprising the further steps of:
comparing the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) with a third pair of threshold values (UTV OL _ SCAV , LTV OL _ SCAV ); and
controlling the air/fuel ratio of the exhaust gases downstream of the exhaust manifold ( 5 ) in open-loop, if the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) is not comprised within the interval defined by the third pair of threshold values (UTV OL _ SCAV , LTV OL _ SCAV ).

6. A method according to claim 1 and comprising the further steps of:
comparing the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) with the minimum air/fuel ratio (λ min ) of the exhaust gases downstream of the exhaust manifold ( 5 ); and
limiting the flow rate (m air _ scav ) of air that is not involved in the combustion taking place inside the cylinders ( 3 ) and flows directly from the intake manifold ( 4 ) into the exhaust pipe ( 10 ), if the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) is smaller than the minimum air/fuel ratio (λ min ) of the exhaust gases downstream of the exhaust manifold ( 5 ).

7. A method according to claim 1 and comprising the further steps of:
comparing the minimum air/fuel ratio (λ min ) of the exhaust gases downstream of the exhaust manifold ( 5 ) with a safety value (SV); and
forbidding the passage of a flow rate (m air _ scav ) of air that is not involved in the combustion taking place inside the cylinders ( 3 ) directly from the intake manifold ( 4 ) into the exhaust pipe ( 10 ), if the minimum air/fuel ratio (λ min ) of the exhaust gases downstream of the exhaust manifold ( 5 ) is greater than the safety value (SV).

8. A method according to claim 1 and comprising the further steps of:
determining the reference value of the air/fuel ratio (λ target ) of the exhaust gases as a function of the flow rate (m air _ scav ) of air that is not involved in the combustion taking place inside the cylinders ( 3 ) and flows directly from the intake manifold ( 4 ) into the exhaust pipe ( 10 );
calculating the difference between the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) and the reference value of the air/fuel ratio (λ target ) of the exhaust gases; and
controlling the supercharged internal combustion engine ( 1 ) as a function of the difference between the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) and the reference value of the air/fuel ratio (λ target ) of the exhaust gases.

9. A method according to claim 8 , wherein the reference value of the air/fuel ratio (λ target ) is variable as a function of the engine point and of the thermal state of the internal combustion engine ( 1 ).

10. A method according to claim 8 and comprising the further step of filtering the difference between the air/fuel ratio (λ meas ) of the exhaust gases downstream of the exhaust manifold ( 5 ) detected by the sensor ( 25 ) and the reference value of the air/fuel ratio (λ target ) of the exhaust gases.

11. A method according to cl

Assignees

• Magneti Marelli Spa

Inventors

• Cavanna Filippo
• Lanzoni Riccardo

Classifications

• F02D41/1454

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• F02D13/0261

  Controlling the valve overlap · CPC title

• F02B25/00

  Engines characterised by using fresh charge for scavenging cylinders · CPC title

• F02M26/05

  High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor · CPC title

• F02D41/0007 Primary

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title