Method to control a burner for an exhaust system of an internal combustion engine

Patent metadata

Field	Value
Publication number	US-11686233-B2
Application number	US-202217809890-A
Country	US
Kind code	B2
Filing date	Jun 29, 2022
Priority date	Jun 30, 2021
Publication date	Jun 27, 2023
Grant date	Jun 27, 2023

Abstract

A method to control an internal combustion engine having an exhaust duct and an exhaust gas after-treatment system comprising at least one catalytic converter arranged along the exhaust duct; an oxygen sensor housed along the exhaust duct and arranged upstream of said at least one catalytic converter; and a burner suited to introduce the exhaust gases into the exhaust duct upstream of the oxygen sensor the method provides the steps of identifying the operation phases in which the internal combustion engine is turned off and the burner is turned on so that the oxygen sensor is exclusively hit by the exhaust gases produced by the burner; acquiring the signal generated by the oxygen sensor; and using the signal generated by the oxygen sensor to determine the objective fuel flow rate and the objective air flow rate to be fed to the burner.

First claim

The invention claimed is:

1. A method to control an internal combustion engine ( 1 ) provided with an exhaust system ( 2 ) for the exhaust gases of a motor vehicle having an exhaust duct ( 10 ) and an exhaust gas after-treatment system ( 14 ) comprising at least one catalytic converter ( 15 , 17 ) arranged along the exhaust duct ( 10 ); and an oxygen sensor ( 18 , 18 *), preferably a linear one, which is housed along the exhaust duct ( 10 ) and is arranged upstream of said at least one catalytic converter ( 15 , 17 ) in order to detect the air/fuel ratio of the exhaust gases providing an output that indicates the content of oxygen in the exhaust gases; and a burner ( 21 ), which is suited to introduce exhaust gases into the exhaust duct ( 10 ) upstream of the oxygen sensor ( 18 , 18 *) so as to speed up the heating of said at least one catalytic converter ( 15 , 17 ), wherein inside the burner ( 21 ) there is defined a combustion chamber ( 22 ), which receives fresh air through an air feeding device ( 23 ), which is provided with a pumping device ( 24 ) feeding air, and fuel from an injector ( 27 ), which is designed to inject fuel into the combustion chamber ( 22 ), and a spark plug ( 28 ) coupled to the burner ( 21 ) so as to ignite the mixture present inside the combustion chamber ( 22 ); the method comprises the following steps:
a) identifying operation phases in which the internal combustion engine ( 1 ) is turned off and the burner ( 21 ) is turned on, so that the oxygen sensor ( 18 , 18 *) is exclusively hit by the exhaust gases produced by the burner ( 21 );
b) acquiring the signal generated by the oxygen sensor ( 18 , 18 *); and
c) using the signal generated by the oxygen sensor ( 18 , 18 *) in order to control the objective air flow rate ({dot over (m)} A_OBJ ) and determine the objective fuel flow rate ({dot over (m)} F_OBJ ) to be fed to the burner ( 21 ).

2. The method according to claim 1 , wherein the identifying step comprises the sub-step of turning on the burner ( 21 ) in one of the following cases:
the door of the driver of the motor vehicle is opened; or
the motor vehicle is a hybrid vehicle, which is started in electric mode, and the internal combustion engine ( 1 ) has not been turned on yet after the motor vehicle has been started; or
the motor vehicle is a hybrid vehicle driving in electric mode, but about to switch to the heat mode.

3. The method according to claim 2 , wherein the identifying step comprises the sub-step of turning off the burner ( 21 ) in one of the following cases:
a temperature of the exhaust system ( 2 ) is detected, which is higher than a limit value ranging from 180° C. to 200° C.; or
a predetermined amount of time has elapsed since the burner ( 21 ) was turned on; or
no passenger is detected to be present on board the motor vehicle for a predetermined amount of time.

4. The method according to claim 1 , wherein the identifying step comprises the sub-step of turning on the burner ( 21 ) in one of the following cases:
the motor vehicle is a hybrid vehicle driving in electric mode with the internal combustion engine ( 1 ) turned off; or
in a release phase with an open clutch; or
during the stopping phases of the motor vehicle.

5. The method according to claim 4 , wherein the identifying step comprises the sub-step of turning off the burner ( 21 ) in one of the following cases:
the internal combustion engine ( 1 ) is turned on; or
a predetermined amount of time has elapsed since the burner ( 21 ) was turned on.

6. The method according to claim 1 , wherein the using step comprises the further sub-steps of:
calculating the thermal power (P OBJ ) needed to reach the nominal operating temperature of said at least one catalytic converter ( 15 , 17 ) obtained with an objective value (λ OBJ ) of the air/fuel ratio; and
determining both the objective fuel flow rate ({dot over (m)} F_OBJ ) and the objective air flow rate ({dot over (m)} A_OBJ ) to be fed to the burner ( 21 ) in order to obtain the thermal power (P OBJ ) needed to reach the nominal operating temperature of said at least one catalytic converter ( 15 , 17 ).

7. The method according to claim 6 and comprising the further steps of:
determining the nominal number (N NOM ) of revolutions with which to operate the pumping device ( 24 ) depending on the objective air flow rate ({dot over (m)} A_OBJ ) and on quantities comprising the ambient pressure (P ATM ), the ambient temperature (T ATM ) and the pressure (P A ) of the air flowing into the burner ( 21 );
determining a closed-loop contribution (N CL ) of the number of revolutions with which to operate the pumping device ( 24 ) by means of a PID controller, which tries to zero a difference between the objective value (λ OBJ ) of the air/fuel ratio and the actual value (λ) of the air/fuel ratio measured by the oxygen sensor ( 18 , 18 *);
determining a further contribution (N ADAT ) of the number of revolutions with which to operate the pumping device ( 24 ) depending on the integral action of the PID controller under stationary conditions;
determining the actual number (N) of revolutions with which to operate the pumping device ( 24 ) by means of the sum of the nominal number (N NOM ) of revolutions, of the closed-loop contribution (N CL ) of the number of revolutions with which to operate the pumping device ( 24 ) and of the further contribution (N ADAT ) of the number of revolutions with which to operate the pumping device ( 24 ).

8. The method according to claim 7 and comprising the further step of signalling a fault in case the sum of the closed-loop contribution (N CL ) and of the further contribution (N ADAT ) of the number of revolutions with which to operate the pumping device ( 24 ) exceeds a predetermined threshold value.

9. The method according to claim 6 and comprising the further step of determining the nominal fuel flow rate ({dot over (m)} FUEL_N ) by means of the following formula:

m
.

FUEL
-
N

=

m
.

A

(

A
F

STEC

*

λ
OBJ

)

{dot over (m)} FUEL-N nominal fuel flow rate;
{dot over (m)} A estimated air flow rate;
A/F STEC stoichiometric air and fuel ratio;
Λ OBJ objective value of the air/fuel ratio.

10. The method according to claim 9 , wherein the estimated air flow rate ({dot over (m)} A ) is calculated by means of the difference between the actual number (N) of revolutions and the further contribution (N ADAT ) of the number of revolutions with which to operate the pumping device ( 24 ) and by means of the quantities comprising the ambient pressure (P ATM ), the ambient temperature (T ATM ) and the pressure (P A ) of the air in a duct ( 25 ) downstream of the pumping device ( 24 ).

11. The method according to claim 9 and comprising the further steps of:
determining a closed-loop contribution ({dot over (m)

Assignees

• Marelli Europe Spa

Inventors

• De Cesare Matteo
• Brugnoni Enrico
• Panciroli Marco
• Stola Federico

Classifications

• F01N2240/14

  a fuel burner · CPC title

• F01N3/204

  using an exhaust gas igniter, e.g. a spark or glow plug, without introducing fuel into exhaust duct · CPC title

• F01N2900/1812

  Flow rate · CPC title

• F01N9/00 Primary

  Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00) · CPC title

• F01N2900/1402

  Exhaust gas composition · CPC title