Internal combustion engine equipped with an aftertreatment device

Abstract

An internal combustion engine includes an aftertreatment device, an injector for injecting fuel into a cylinder and an Electronic Control Unit configured to perform a regeneration process of the aftertreatment device. The regeneration process includes determining a nominal fuel quantity to be injected by an after-injection; monitoring a temperature value of the aftertreatment device; determining a fuel quantity correction value, as a function of a difference between the monitored temperature value and a target temperature value of the aftertreatment device; correcting the nominal fuel quantity value, using the fuel quantity correction value, in order to determine a corrected fuel quantity value; performing a fuel injection cycle including a plurality of after-injections; and injecting the corrected fuel quantity value into the cylinder during one of the after-injections of the cycle.

Claims

1. An internal combustion engine comprising: an injector configured to inject fuel into a cylinder of the engine; an aftertreatment device in fluid communication with the cylinder and configured to remove pollutants from a fluid exhausted from the cylinder; and an electronic control unit configured to execute a regeneration process of the aftertreatment including: determine a nominal fuel quantity to injea with the injector during an after-injection; monitor a temperature value of the aftertreatment device; determine a fuel quantity correction value, as a function of a difference between the monitored temperature value and a target temperature value of the aftertreatment device, by multiplying the monitored temperature value by a coefficient, wherein the coefficient is based on a type of the aftertreatment device subjected to the regeneration process; correct the nominal fuel quantity value, using the fuel quantity correction value, in order to provide a corrected fuel quantity value; perform a fuel injection cycle including the after-injection; and inject the corrected fuel quantity value into the cylinder during the after-injection.

2. The engine according to claim 1, further comprising a temperature sensor associated with the aftertreatment device, wherein the electronic control unit is configured to determine a fuel quantity correction value when the temperature value of the aftertreatment device is higher than a minimum aftertreatment device temperature value.

3. The engine according to claim 2, wherein the electronic control unit is configured to check a fault state in at least one of the injector and the temperature sensor and determine a fuel quantity correction value when the fault stat indicates no faults in the injector or the temperature sensor.

4. The engine according to claim 1, wherein the electronic control unit is configured to determine a fuel quantity correction value when an aftertreatment device regeneration combustion mode is active.

5. The engine according to claim 1, further comprising a low-pass filter configured to filter the fuel quantity correction value.

6. The engine according to claim 1, wherein the electronic control unit is configured to inject the corrected fuel quantity value into the cylinder as a last after-injection of the fuel injection cycle.

7. The engine according to claim 1, wherein the electronic control unit is configured to add the fuel quantity correction value to the nominal fuel quantity value when the difference between the monitored temperature value and the desired temperature value of the aftertreatment device is negative.

8. The engine according to claim 1, wherein the electronic control unit is configured to subtract the fuel quantity correction value from the nominal fuel quantity value when the difference between the monitored temperature value and the desired temperature value of the aftertreatment device is positive.

9. A method for regenerating an aftertreatment device in the exhaust of an internal combustion engine having an injector configured to inject fuel into a cylinder of the engine, the method comprising: determining a nominal fuel quantity to inject with the injector during an after-injection; monitoring a temperature value of the aftertreatment device; determining a fuel quantity correction value, as a function of a difference between the monitored temperature value and a target temperature value of the aftertreatment device, by multiplying the monitored temperature value by a coefficient, wherein the coefficient is based on a type of the aftertreatment device subjected to the regeneration process; correcting the nominal fuel quantity value, using the fuel quantity correction value, in order to provide a corrected fuel quantity value; performing a fuel injection cycle including the after-injection; and injecting the corrected fuel quantity value into the cylinder during the after-injection.

10. The method according to claim 9, further comprising determining a fuel quantity correction value when a temperature value of the aftertreatment device is higher than a minimum aftertreatment device temperature value.

11. The method according to claim 10, further comprising: checking a fault state in at least one of the injector and a temperature sensor associated with the aftertreatment device; and determining a fuel quantity correction value when the fault state indicated no fault in the injector or the temperature sensor.

12. The method according to claim 9, further comprising determining the fuel quantity correction value when an aftertreatment device regeneration combustion mode is active.

13. The method according to claim 9, further comprising low-pass filtering the fuel quantity correction value.

14. The method according to claim 9, further comprising injecting the corrected fuel quantity value into the cylinder as a last after-injection of the fuel injection cycle.

15. The method according to claim 9, further comprising adding the fuel quantity correction value to the nominal fuel quantity value when the difference between the monitored temperature value and the desired temperature value of the aftertreatment device is negative.

16. The method according to claim 9, further comprising subtracting the fuel quantity correction value from the nominal fuel quantity value when the difference between the monitored temperature value and the desired temperature value of the aftertreatment device is positive.

17. An internal combustion engine comprising: an injector configured to inject fuel into a cylinder of the engine; an aftertreatment device in fluid communication with the cylinder and configured to remove pollutants from a fluid exhausted from the cylinder; and an electronic control unit configured to execute a regeneration process of the aftertreatment including: determine a nominal fuel quantity to inject with the injector during an after-injection; monitor a temperature value of the aftertreatment device; determine a fuel quantity correction value, as a function of a difference between the monitored temperature value and a target temperature value of the aftertreatment device; correct the nominal fuel quantity value, using the fuel quantity correction value, in order to provide a corrected fuel quantity value; perform a fuel injection cycle including a plurality of after-injections; and inject the corrected fuel quantity value into the cylinder during a last after-injection of the plurality of after-injections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.

(2) FIG. 1 shows an automotive system;

(3) FIG. 2 is a cross-section of an internal combustion engine belonging to the automotive system of FIG. 1;

(4) FIG. 3 is a schematic view of a portion of an aftertreatment system for an internal combustion engine;

(5) FIG. 4 is a graph representing several parameters as a function of time during the actuation of an embodiment of the present disclosure; and

(6) FIG. 5 is a flowchart describing an embodiment of the method of the present disclosure.

DETAILED DESCRIPTION

(7) The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. Exemplary embodiments will now be described with reference to the enclosed drawings without intent to limit application and uses.

(8) Some embodiments may include an automotive system 100, as shown in FIGS. 1 and 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145. A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150. A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received from a fuel source 190. Each of the cylinders 125 has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

(9) The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of varies prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

(10) The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NO.sub.x traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters. Other embodiments may include an exhaust gas recirculation (EGR) system 300 '8 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

(11) The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110. The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445. Further sensors may be present in the automotive system 100, as better detailed herein below. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

(12) Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with a memory system, or data carrier 460, and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the CPU to carry out the steps of such methods and control the ICE 110.

(13) The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the automotive system 100 it is normally visible as a computer program product, which is also called computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, said carrier being transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.

(14) An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulation technique such as QPSK for digital data, such that binary data representing said computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a Wi-Fi connection to a laptop.

(15) In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a retrievable way in or on this storage medium. The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.

(16) Instead of an ECU 450, the automotive system 100 may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the vehicle.

(17) With reference now to FIG. 3, a schematic view of a portion of an aftertreatment system for the internal combustion engine 110 is illustrated. In the embodiment depicted in FIG. 3, for simplicity only one aftertreatment device 280 is represented in the various embodiments of the present disclosure, the aftertreatment device 280 may be, in turn, a DPF or a LNT or other catalytic aftertreatment devices. In the exhaust line 275, a turbine inlet temperature sensor 500 is present, as well as temperature sensors 510, 520 upstream and downstream of the aftertreatment device 280.

(18) FIG. 4 is a graph representing several parameters as a function of time during the actuation of an embodiment of the present disclosure. In particular, curve A represents a fuel after-injection quantity injected in an after-injection pulse, in particular in the last after-injection pulse of a fuel injection cycle. After time t.sub.0, the fuel after-injection quantity is increased. As a consequence, by continuously applying the increased after-injection quantity, both turbine temperature (curve C) an aftertreatment device temperature (curve B) are increased. For example, after 20-40 seconds, in the automotive system 100 the thermal limits of turbine temperature (790-810 degrees) is reached. For other automotive systems, different values may apply.

(19) FIG. 5 is a flowchart describing an embodiment of the method of the present disclosure, which is performed in connection with multiple after injections in a single combustion cycle. A nominal fuel quantity V_AfterDefault to be injected in an after-injection of the cycle is evaluated at block 600. The nominal after injection quantity is calculated as a function of the engine operating point and, eventually, of other parameters by means, for example, of a map stored in data carrier 460 associated to the ECU 450.

(20) Furthermore, a set of enabling conditions is monitored at block 610 in order to determine if it is possible to perform the subsequent steps of the various embodiments of the method. The specific enabling conditions will be described in more detail herein below.

(21) A temperature value T_cat upstream of the aftertreatment device 280 is monitored, for example by employing aftertreatment device upstream temperature sensor 510, and if this temperature is different from a target temperature T_cat_target of the catalytic device, a fuel quantity correction value V_AfterCorrection is determined at block 630. Then the nominal fuel quantity V_AfterDefault is corrected using the fuel quantity correction value V_AfterCorrection, in order to determine a corrected fuel quantity value V_AfterCorrected at block 640. Finally, the corrected fuel quantity value V_AfterCorrected is injected into the cylinder 125 at block 650.

(22) Determination of the fuel quantity correction value V_AfterCorrection as a function of the monitored temperature value T_cat of the catalytic device is performed only if the temperature value T_cat of the catalytic device is higher than a minimum catalytic device temperature value T_cat_min, in order to avoid excessive fuel consumption. Moreover, determination of a fuel quantity correction value V_AfterCorrection as a function of the monitored temperature value T_cat of the catalytic device is performed only if no faults are detected.

(23) Also, determination of a fuel quantity correction value V_AfterCorrection as a function of the monitored temperature value T_cat of the catalytic device is performed only if an aftertreatment device regeneration combustion mode is active. In particular, the determination of the fuel quantity correction value V_AfterCorrection is performed by multiplying the monitored temperature value T_cat by a coefficient of proportionality k, the coefficient of proportionality k being chosen as a function of the type of aftertreatment device 280 subjected to the regeneration process.

(24) For example a specific coefficient k.sub.DPF may be chosen, if a DPF regeneration must be performed, or a specific coefficient k.sub.LNT may be chosen, if a LNT regeneration must be performed and so on. These coefficients may be determined by an experimental activity and then stored in the data carrier 460 associated to the ECU 450. Furthermore, a low-pass filtering may be applied to the fuel quantity correction value V_AfterCorrection, in order to avoid an excessive number of corrections.

(25) Preferably, the corrected fuel quantity value V_AfterCorrected is injected into the cylinder 125 in the last after-injection of the cycle. To perform in practice the after-injection fuel quantity correction, the fuel quantity correction value V_AfterCorrection is added to the nominal fuel quantity value V_AfterDefault, if the difference between the monitored temperature value T_cat and the desired temperature value T_cat_target of the aftertreatment device 280 is negative. In this case, this embodiment of the method improves regeneration efficiency by increasing the temperature upstream of the aftertreatment device and helps to avoid soot cake and lambda clogging.

(26) In the alternative, the fuel quantity correction value V_AfterCorrection is subtracted to the nominal fuel quantity value V_AfterDefault, if the difference between the monitored temperature value T_cat and the desired temperature value T_cat_target of the aftertreatment device 280 is positive. In this case, this embodiment of the method improves component protection, such as the turbine by avoiding excessive temperatures at the inlet thereof.

(27) While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.