Patent Application
20230032897
This patent application claims priority from Italian patent application no. 102021000020318 filed on Jul. 29, 2021, the entire disclosure of which is incorporated herein by reference.
The invention relates to a method to control an exhaust gas after-treatment system for an exhaust system of an internal combustion engine.
An internal combustion engine is typically provided with a number of cylinders, each connected to an intake manifold and to an exhaust manifold, to which an exhaust duct is connected in order to feed the exhaust gases produced by the combustion an exhaust system, which releases the exhaust gases produced by the combustion into the atmosphere.
An exhaust gas after-treatment system usually comprises a pre-catalytic converter, which is arranged along the exhaust duct; a particulate filter, which is also arranged along the exhaust duct, downstream of the pre-catalytic converter; and a catalytic converter, which is arranged along the exhaust duct, upstream of the particulate filter.
The exhaust gas after-treatment system finally comprises, in addition, a burner, which is suited to introduce exhaust gases (and, as a consequence, heat) into the exhaust duct in order to speed up the heating of the catalytic converter and so as to facilitate the regeneration of the particulate filter. Inside the burner there is defined a combustion chamber, which receives fresh air from an air feeding circuit and receives fuel from an injector, which is suited to inject fuel into the combustion chamber. Furthermore, a spark plug is coupled to the burner in order to ignite the mixture present inside the combustion chamber.
The exhaust gases produced by the burner have a pollutant concentration that proves to be particularly high during an initial burner starting phase. During this initial phase, the temperature of the catalytic converter is lower than the activation temperature and, therefore, the catalytic converter has an extremely low power of conversion of the pollutants produced by the burner.
Hence, the pollutants released into the atmosphere and produced both by the internal combustion engine and by the burner, especially during the burner starting phase, must be reduced.
The object of the invention is to provide a method to control an exhaust gas after-treatment system for an exhaust system of an internal combustion engine, which does not suffer from the drawbacks described above and, in particular, is easy and economic to be implemented.
According to the invention there is provided a method to control an exhaust gas after-treatment system for an exhaust system of an internal combustion engine according to the appended claims.
The invention will now be described with reference to the accompanying drawings showing a non-limiting embodiment thereof, wherein:
In
The intake manifold 4 receives a gas mixture comprising both exhaust gases and fresh air, i.e. air coming from the outside through an intake duct 6, which is provided with an air filter for the fresh air flow and is regulated by a throttle valve 8. Along the intake pipe 6, downstream of the air filter 7, there also is an air flow meter 9.
The exhaust manifold 5 is connected to an exhaust duct 10, which feeds the exhaust gases produced by the combustion to the exhaust system 2, which releases the gases produced by the combustion into the atmosphere.
The supercharged internal combustion engine 1 comprises supercharging system 11 for the internal combustion engine 1 obtained by means of a turbocharger 11 provided with a turbine 12, which is arranged along the exhaust duct 10 so as to rotate at a high speed due to the action of the exhaust gases expelled from the cylinders 3, and a compressor 13, which is arranged along the intake duct 6 and is mechanically connected to the turbine 12 so as to be caused to rotate by the turbine 12 itself in order to increase the pressure of the air present in the feeding duct 6.
The exhaust system 2 is provided with an exhaust gas after-treatment system 14 comprising a pre-catalytic converter 15 arranged along the exhaust duct 10, downstream of the turbocharger 11, and a particulate filter 16 (also known as Gasoline Particulate Filter) also arranged along the exhaust duct 10, downstream of the pre-catalytic converter 15. According to a preferred variant, the exhaust gas after-treatment system 14 is provided with a catalytic converter 17 arranged along the exhaust duct 10, upstream of the particulate filter 16. According to a preferred embodiment, the catalytic converter 17 and the particulate filter 16 are arranged one after the other on the inside of a common tubular container.
According to a first variant, the internal combustion engine 1 is further provided with a UHEGO or UEGO linear oxygen sensor 18 housed along the exhaust duct 10 and interposed between the turbocharger 11 and the pre-catalytic converter 15 to detect the air/fuel ratio of the exhaust gases (providing a liner output that indicates the content of oxygen in the exhaust gases) downstream of the turbocharger 11 and upstream of the pre-catalytic converter 15.
The internal combustion engine is further provided with a lambda sensor 19, which is suited to provide an on/off binary output, which indicates whether the air/fuel ratio of the exhaust gases is higher or lower than the stoichiometric value, is housed along the exhaust duct 10 and is interposed between the pre-catalytic converter 15 and the assembly defined by the catalytic converter 17 and the particular filter 16 in order to detect the concentration of oxygen in the exhaust gases downstream of the pre-catalytic converter 15; and, finally, a lambda sensor 20, which is suited to provide an on/off binary output, which indicates whether the air/fuel ratio of the exhaust gases is higher or lower than the stoichiometric value, is housed along the exhaust duct 10 and is arranged downstream of the assembly defined by the catalytic converter 17 and the particular filter 16 in order to detect the concentration of oxygen in the exhaust gases downstream of the assembly defined by the catalytic converter 17 and the particular filter 16.
The exhaust gas after-treatment system 14 further comprises a burner 21, which is suited to introduce exhaust gases (and, as a consequence, heat) into the exhaust duct 10 in order to speed up the heating of the pre-catalytic converter 15 and/or of the catalytic converter 17 and so as to facilitate the regeneration of the particulate filter 16. The burner 21 is arranged so as to introduce exhaust gases into the exhaust duct 10 upstream of the pre-catalytic converter 15 or downstream of the catalytic converter 17.
According to
The combustion chamber 22 further receives fuel from an injector 27, which is suited to inject fuel into the combustion chamber 22. Furthermore, a spark plug 28 is coupled to the burner 21 in order to ignite the mixture present inside the combustion chamber 22. The internal combustion engine 1 also comprises a fuel feeding circuit 29 provided with a pumping device 30, which feeds fuel by means of a duct 31, which is adjusted by a valve 38.
The internal combustion engine 1 finally comprises a control system 32, which is designed to control the operation of the internal combustion engine 1. The control system 32 comprises at least one electronic control unit (also known as “ECU”), which controls the operation of the different components of the internal combustion engine 1.
The spark plug 28 is controlled by the electronic control unit ECU so as to generate a spark between its electrodes, thus determining the ignition of the gases compressed inside the combustion chamber 22. The control system 32 further comprises a plurality of sensors connected to the electronic control unit ECU.
The sensors comprise, in particular, a temperature and pressure sensor 33 for the air flow fed to the burner 21, which is preferably housed along the duct 25; a temperature and pressure sensor 34 for the exhaust gases flowing out of the burner 21, which is housed along an outlet duct 35; a pressure sensor 36 for the fuel fed to the burner 21, which is housed along the duct 31. The electronic control unit ECU is further connected to the UHEGO or UEGO linear oxygen sensor 18 and to the lambda sensors 19, 20, from which it receives signals indicative of the air/fuel ratio of the exhaust gases.
In
The dashboard 40 is further provided with a plurality of graphic areas indicated with 44. In the particular example described herein, the graphic areas 44 comprises a graphic area 44* where a road map is displayed in order to assist the driver while driving and a graphic area 44** comprising, in turn, a number of indicators 45 (or lights 45) suited to provide the driver with respective items of information of the drive and/or on the state of the vehicle.
In particular, the graphic area 44** comprises an indicator 45 controlled by the electronic control unit ECU and designed to provide indications concerning the burner 21.
In use, the normal operation of the exhaust gas after-treatment system 14 entails the work conditions disclosed in the description below.
During a starting step, the electronic control unit ECU is suited to keep the indicator 45 turned on. In this starting step, the internal combustion engine 1 is turned off while the burner 21 is caused to turn on. During the starting step, the temperature of the pre-catalytic converter 15 and/or of the catalytic converter 17 is lower than an activation temperature and the concentration of pollutants produced by the burner 21 (detected by one of the sensors 18, 19, 20 downstream of the burner 21) is greater than a limit value. The starting step starts when the electronic control unit ECU detects the presence of the key and/or when the doors are unlocked through a command of the driver from the remote control.
On the other hand, the starting step ends when the electronic control unit ECU detects a temperature of the pre-catalytic converter 15 and/or of the catalytic converter 17 higher than or equal to the activation temperature; once the staring step has ended, the electronic control unit ECU is suited to turn off the indicator 45 and the driver can turn on the internal combustion engine 1.
In case the driver decides to turn on the internal combustion engine 1 before the indicator 45 is turned off (i.e., in other words, before the starting step has ended and before the temperature of the pre-catalytic converter 15 and/or of the catalytic converter 17 is higher than or equal to the activation temperature), the electronic control unit ECU is suited to keep the indicator 45 turned on until the following turning off of the internal combustion engine 1.
Alternatively, as soon as a fault/malfunction of the burner 21 is detected, the electronic control unit ECU is suited to cause the indicator 45 to turn on so as to warn the driver of the fault/malfunction.
In case the burner 21 needs to be manually turned on by the driver of the vehicle, the indicator 45 is suited to warn the driver of the need to start the burner 21. The indicator 45 is turned on when the electronic control unit ECU detects the presence of the key and/or when the doors are unlocked through a command of the driver from the remote control, so that the driver can start the burner 21. Then, the indicator 45 is turned off when the electronic control unit ECU detects a temperature of the pre-catalytic converter 15 and/or of the catalytic converter 17 higher than or equal to the activation temperature.
The temperature of the pre-catalytic converter 15 and/or of the catalytic converter 17 can alternatively be detected by means of dedicated sensors or estimated by the electronic control unit ECU.
It is evident that the electronic control unit ECU disclosed in the description above can be a dedicated control unit ECU, which controls the operation of the burner 21, or can be the electronic control unit ECU controlling the operation of the internal combustion engine 1. Furthermore, it should be pointed out that the connection between the electronic control unit ECU and the indicator 45 can alternatively be obtained by means of a CAN or wired connection.
The exhaust gas after-treatment system 14 and the method described so far feature several advantages; in particular, they reduce the pollutants released into the atmosphere produced by the burner 21 during the starting step of the burner 21.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021000020318 | Jul 2021 | IT | national |
