GB2533609A

GB2533609A - An internal combustion engine equipped with a lean NOx trap

Info

Publication number: GB2533609A
Application number: GB1423069.2A
Authority: GB
Inventors: Argolini Roberto; Castorina Francesco
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2014-12-22
Filing date: 2014-12-22
Publication date: 2016-06-29

Abstract

An internal combustion engine 110 comprises a Lean NOx Trap (LNT) 285 disposed in an exhaust gas line 275, only one Lambda sensor 433, disposed in the exhaust gas line 275 upstream of the Lean NOx Trap 285, a first temperature sensor 431 disposed upstream of the Lean NOx Trap 285 and a second temperature sensor 432 is disposed downstream of the Lean NOx Trap 285. A particulate filter 286 may be provided downstream of the Lean NOx Trap 285. An ECU 450 may start DeNOx regeneration of the NOx Trap 285; monitor engine speed, engine torque and Lambda value; determine rate of regeneration on the basis of engine speed, engine torque, Lambda value, and a value of stored mass in the NOx trap 285 at the start of regeneration; monitor elapsed time; multiply the DeNOx rate by the time value to calculate percentage regeneration, and end regeneration when the calculated percentage reaches a threshold value.

Description

S AN INTERNAL COMBUTION ENGINE EQUIPPED WITH A LEAN NOx TRAP

TECHNICAL FIELD

This invention relates to an internal combustion engine. In particular, the present invention relates to an internal combustion engine and an automotive system equipped with a Lean NO Trap in the exhaust gas line.

BACKGROUND

It is known that exhaust gas after-treatment devices of an internal combustion engine can be provided, among other devices, with a Lean NO Trap (LNT) which represents a cost efficient alternative to SCR (Selective Catalytic Reduction).

A Lean NOx Trap (LNT) traps nitrogen oxides (NOx) contained In the exhaust gas and is located in the exhaust gas line.

Indeed, a LNT is a catalytic device containing catalysts, such as Rhodium, Pt and Pd, and adsorbents, such as barium based elements, which provide active sites suitable for binding the nitrogen oxides (NO.) contained in the exhaust gas, in order to trap them within the device itself.

Lean NOx Traps (LNT) are subjected to periodic regeneration processes or s, whereby such regeneration s are generally provided to release and reduce the trapped nitrogen oxides (NOx) from the LNT.

For this reason, LNT is operated cyclically, for example by switching the internal combustion engine from a lean burn operation mode to a rich operation mode, performing regeneration s, like a DeN0x regeneration or like a DeS0x regeneration.

For example, during normal operation of the internal combustion engine (i.e. during a loading phase), the NO (and/or Solfur Oxides, SO.) are stored on an adsorbent active site (or surface) of the LNT. When the engine is switched to a rich operation mode (i.e. when a rich fuel mixture is injected in the engine combustion chamber), the NO (and or SON) react with the reductants in the exhaust gas and are desorbed and reduced, e.g. converted to nitrogen, thereby regenerating the adsorbent active sites of the catalyst.

The DeNO. regeneration s, for example, may last for a short period each, such as 5 to 8 seconds or more, in which the Lean NO Trap may be cleaned up and its storage capacity recovered. The rich fuel mixture provides a rich atmosphere (lack of oxygen i.e. lambda values < 1) that favours the reactions that are needed to regenerate the LNT.

The duration of a DeN0x regeneration should be defined in order to be sure to empty the LNT with the maximum efficiency, in such a way to restore its storage properties, and in order to reduce fuel consumption and pollutants emissions, instantaneously and throughout the DeN0x regeneration period and the vehicle life time.

For the purpose of determining the duration of the DeNO. regeneration, generally, the internal combustion engine comprises a first Lambda sensor (also known as UEGO) disposed in the exhaust gas line upstream of the LNT and a second Lambda sensor disposed in the exhaust gas line downstream of the LNT.

The main physical evidence that a DeNO. regeneration has been successfully performed 25 and the LNT is empty is given by the Lambda breakthrough, meaning the crossing between the Lambda values of Lambda Sensors Downstream and Upstream of the LNT.

During a DeN0x regeneration, the value read by the second Lambda sensor downstream LNT is not related to the combustion mixture, but it is affected by the chemical reactions that occur inside the LNT: consumption of Oxygen stored in LNT due to OSC (Oxygen 5 Storage Capacity), formation of H2 from CO, release and conversion of stored NON.

The theoretical output of the second Lambda sensor is the following: during the release and conversion of stored NO, the Lambda value downstream of the LNT is higher than the Lambda value upstream of the LNT. When the trap is empty, namely when all the NO have been released, the Lambda value downstream of the LNT should get to the same value of the Lambda value upstream of the LNT.

Instead, because of the diffusive effect that the H2 has on the Lambda sensor output (at the same air-fuel ratio, a higher concentration of Hydrogen shifts the Lambda sensor signal towards richer values), the second Lambda sensor signal crosses the first Lambda sensor signal and stabilizes on a lower value.

In the real case, the two Lambda sensors do not align at the same value, therefore the end of the physical regeneration is generally identified with the moment when the second Lambda sensor signal crosses the one of the first Lambda sensor.

An object of an embodiment of the invention is to provide a cost efficient alternative to the known internal combustion engine at the same time maintaining an efficient control on the 20 duration of the LNT regeneration s (e.g. DeN0x regeneration s and/or DeS0x regeneration s).

These and other objects are achieved by the embodiments of the invention having the features recited in the independent claims. The dependent claims delineate preferred and/or especially advantageous aspects.

SUMMARY

An embodiment of the disclosure provides an internal combustion engine comprising an exhaust gas line, a Lean NOx Trap disposed in the exhaust gas line, - only one Lambda sensor disposed in the exhaust gas line, wherein the only one Lambda sensor is disposed upstream of the Lean NOx Trap, and - two temperature sensors disposed in the exhaust gas line, wherein a first temperature sensor is disposed upstream of the Lean NOx Trap and a second temperature sensor is disposed downstream of the Lean NOx Trap.

Thanks to this architecture, is provided a more economical internal combustion engine respect to the known internal combustion engine architectures.

According to an aspect of the invention, the internal combustion engine may comprise a particulate filter which is disposed in the exhaust gas line downstream of the Lean NOx Trap.

Thanks to this solution, it can be achieved a reduction of the particulate matter or soot emitted by internal combustion engine.

According to a further aspect of the invention, the exhaust gas line comprises a first connector pipe connecting an exhaust manifold to an inlet of the Lean NO Trap and a second connector pipe connecting an outlet of the Lean NO Trap to an inlet of the particulate filter.

In particular, the only one Lambda sensor is disposed in the first connector pipe. Moreover, the first temperature sensor is disposed in the first connector pipe and the second temperature sensor is disposed in the second connector pipe.

Thank to this solution, a rational and economical solution of the exhaust as line architecture may be achieved.

According to an embodiment of the invention, the internal combustion engine may comprise an electronic control unit configured to perform the steps of: - starting a DeN0x regeneration of the Lean NO Trap, - monitoring an engine speed value, an engine torque value, and a Lambda value upstream of the Lean NOx Trap by means of the only one Lambda sensor, - determining a DeNO. rate of progress for the DeN0x regeneration on the basis of the engine speed value, the engine lorque value, the Lambda value and a value of a NO stored mass in the Lean NOx Trap at the start of the DeN0x regeneration, - monitoring an elapsed time value starting from the beginning of DeN0x regeneration, - multiplying the DeN0x rate of progress by the elapsed time value in order to calculate a percentage of the DeNO. regeneration performed, - ending the DeN0x regeneration when the percentage of the DeN0x regeneration performed reaches a predefined threshold value.

Thanks to this embodiment the duration of a DeNO. regeneration may be determined in a precise and simple way during the entire life time of the Lean NO Trap.

Moreover, in an internal combustion engine having the simplified architecture described above, the Lean NOx Trap may however be efficiently controlled during its entire life time and during any regeneration has to be performed for its restoration of the initial storage properties thereof.

According to a further embodiment of the invention, the determination of the DeN0x rate of progress is performed using the engine speed value and the engine torque value to determine an engine working point factor representative of the effect of the engine performance on the DeN0x rate of progress and using the Lambda value upstream of the Lean NO Trap and the value of the NO stored mass in the Lean NO Trap at the start of the regeneration to determine a regeneration factor of the Lean NO Trap representative of the effect of the Lean NO Trap parameters on the DeNO. rate of progress and determining the DeNO. rate of progress as a function of the engine working point factor and of the regeneration factor of the Lean NO Trap.

Thank to this embodiment it is allowed a quick calculation of the main factors influencing the rate of regeneration of a Lean NO trap.

According to a further embodiment of the invention, the engine working point factor may be expressed as the output of a map that receives as input an engine speed value and an engine torque value.

Thank to this embodiment it can be allowed a fast calculation of the engine working point factor.

According to an another embodiment of the invention, the regeneration factor of the Lean NO Trap may be expressed as the output of a map that receives as input a Lambda value measured upstream of the Lean NO Trap and the value of a stored mass in the Lean NO Trap at the start of the regeneration.

In this way it can be allowed to take into account the conditions of the Lean No Trap. According to another embodiment of the invention, the engine working point factor may be calculated by: - using a first map representative of a new Lean NO Trap, the first map receiving as input an engine speed value and an engine torque value, using a second map representative of an aged Lean NO Trap, the second map receiving as input an engine speed value and an engine torque value, monitoring the actual age of the Lean NO. Trap to determine an ageing factor of the Lean NO Trap, and - calculating the engine working point factor by interpolation of the output values of the first and the second map taking into account the ageing factor of the Lean NO Trap. Thanks to this embodiment it can be allowed to take into account the aging conditions of the Lean Nox Trap.

According to an aspect of the invention, the DeN0x rate of progress for the regeneration is determined according to the formula: KoeNox = KwrkPnt * KRgn, wherein: KDeN0x is the rate of progress for the regeneration, e.g. in units of %/sec.

Kwxxpnt is the engine working point factor and, e.g. in units of %/sec.

KRgn is the dimensionless regeneration factor of the Lean NOx Trap.

Another embodiment of the invention provides an automotive system, in particular a passenger car, comprising an internal combustion engine, as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an automotive system; Figure 2 is a cross-section of an internal combustion engine belonging to the automotive system of figure 1; Figure 3 is a schematic representation of some elements of the automotive system of figure 1; Figure 4 is a schematic representation of the main steps of a first embodiment of the invention; and Figure 5 is a schematic representation of the main steps of a further embodiment of the 25 invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Some embodiments may include an automotive system 100, as shown in Figures 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.

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 pods 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust gas aftertreatment system 270. This example shows a variable geometry turbine (VGT) 250 with a VGT actuator 290 arranged to move the vanes to after the flow of the exhaust gases through the turbine. In other embodiments, the turbocharger may be a fixed geometry turbine including a waste gate. The exhaust gas aftertreatment system 270 may include an exhaust gas line 275 having one or more exhaust aftertreatment devices 280.

The exhaust gas line 275, shown also in figure 3, may include an exhaust gas pipe 276 having one or more of said exhaust aftertreatment devices 280. The aftertreatment devices 280 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), for example an oxidation catalyst (i.e. Diesel Oxidation Catalyst, DOC) and a Lean NOx Traps (LNT 285). Other examples of aftertreatment devices 280 include a particulate filter (i.e. a Diesel Particulate Filter, DPF 286 as described above) and a selective catalytic reduction (SCR) systems. Other embodiments may include an exhaust gas recirculation (EGR) system 300 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.

In the present example, the LNT 285, which traps nitrogen oxides (NO) contained in the exhaust gas flowing along the exhaust gas line 275, is located in the exhaust gas line 275 along the exhaust gas pipe 276 upstream of the DPF 286, and for example downstream of the turbine 25.

For example, in some embodiments, the LNT 285 may be integrated and/or combined with 25 the DPF 286.

In detail, the LNT 285 is a catalytic device containing catalysts, such as Rhodium, Pt and Pd, and adsorbents, such as barium based elements, which provide active sites suitable for binding the nitrogen oxides (NO.) contained in the exhaust gas, in order to trap them within the device itself.

In the example shown in figure 3, the exhaust gas pipe 276 may comprise a plurality of connector pipes 277,278 connecting the exhaust aftertreatment devices 280. In particular, a first connector pipe 277 may connect the exhaust manifold 225 to an inlet of the LNT 285 (for example, via the turbine 250) and a second connector pipe 278 connects an outlet of the LNT 285 to an inlet of the DPF 286. The DPF 286 has an outlet pipe which may release exhaust gas to the environment, or may be connected to other components, for example a selective catalytic reduction (SCR) systems, a muffler (not shown) or other components.

The second connector pipe 278, in the example in which the LNT 285 is integrated with the DPF 286, may be defined as a portion of a common casing enclosing both the LNT 15 285 and the DPF 286.

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, pressure, 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.

In particular, as shown in figure 3, the automotive system 100 comprises a first temperature sensor 431 disposed in the exhaust gas line 275 upstream of the LNT 285, and in particular the first temperature sensor 431 is disposed in the first connector pipe 277.

Moreover, the automotive system 100 comprises a second temperature sensor 432 disposed in the exhaust gas line 275 downstream of the LNT 285 and upstream of the DPF 286, and in particular the second temperature sensor 432 is disposed in the second connector pipe 278.

According to the embodiment illustrated in figures 1 and 3, the exhaust gas aftertreatment 10 system 270, the automotive system 100 comprises only one Lambda sensor 433 disposed in the exhaust gas line 275.

In particular, the only one Lambda sensor 433 is disposed upstream of the LNT 285, ad by way of an example the only one Lambda sensor 433 is disposed in the first connector pipe 277.

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 injector 160, the throttle body 330, the EGR Valve 320, the waste gate 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.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU 460) in communication with a memory system 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 carryout out the steps of such methods and control the ICE 110.

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.

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 modulated technique such as OPSK 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 WiFi connection to a laptop.

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.

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.

Figure 3 shows, in a schematic way and omitting some devices for simplicity, the ICE 110 managed by the ECU 450 equipped with a CPU 460; the ICE 110 is equipped with the exhaust aftertreatment devices 280 which, in the exhaust gas line 275, comprise the LNT 285 and the DPF 286, this latter disposed downstream of the LNT 285 as disclosed above. According to an embodiment of the invention, the ECU 450 may be configured to start a regeneration of the LNT 285, for example a DeNO. regeneration.

A DeNO. regeneration of the LNT 285 can be performed by a rich combustion phase generated, for example, by a plurality of fuel after-injections into cylinders 125 and performed by fuel injectors 160 under management of the engine ECU 450 of the ICE 110.

More specifically, the procedure to change a combustion mode from a normal operation mode to one of the typical LNT regeneration modes is the following.

The ECU 450 commands the engine actuators, such as EGR valve, Swirl valve, Throttle valve, VGT actuator, Rail Pressure Pump, and as above mentioned fuel injectors 160, in order to move them to dedicated set points, pre-calibrated and stored in the memory system, that create an exhaust gas condition that is necessary to promote the chemical reactions in the LNT 285 that are the base of each typical LNT phase, such as NO storage, NO conversion, SO. storage, SO. desorption.

As shown in figures 4 and 5, during the staled DeNO. regeneration the ECU 450 may be configured to determine (block 500) an engine working point factor Kw.kpot.

The engine working point factor Kwapn, may be considered as representative of the effects on the DeNO. regeneration given by the ICE 110 operating conditions.

The ICE 110 working point factor K...kpn, can be expressed as the output of a map, pre-calibrated on a test bench and stored in the memory system, that receives as input an (actual) engine speed value and an engine torque value. The map is defined in such a way to cover all the engine speed and torque range values under which a DeNO. regeneration may occur.

Furthermore, a regeneration factor KRgn of the LNT 285 may be determined (block 510) by the ECU 450.

The regeneration factor KRgn may be considered as indicative of the effects on the DeNO. regeneration given by the LNT 285 operating conditions.

In particular, the regeneration factor KRgn allows to consider the different effects of NO stored mass on an optimal duration of the DeNO. regeneration at different Lambda values. The regeneration factor KR" of the LNT 285 is expressed as the output of a further map, pre-calibrated on a test bench and stored in the memory system, that receives as input a Lambda value measured upstream of the LNT 285, i.e. measured by the only one Lambda sensor, and a value of a stored mass of NO in the LNT 285 at the start of the DeNO. regeneration.

The value of the stored mass of NO in the LNT 285 at the start of the DeNO. regeneration 15 can be determined in a number of ways.

A first possibility is to use a mathematical model chosen from any model known in the art for LNT NO stored mass calculation.

A second possibility is to employ, if present on the automotive system 100, an inlet and an outlet NO sensor.

Another possibility is to employ an inlet NO sensor and a model to calculate NO stored mass in the LNT 285.

With these parameters, a DeNO. rate of progress KDenriox for the DeNO. regeneration is determined on the basis of the engine working point factor Kwrkpni and of the regeneration factor KR" of the LNT 285.

The DeNO. rate of progress for the regeneration KDeNOx can be determined (block 515 of figure 4) by means of the following formula: KDeN0x = KuckPhi * KRgn The Della< rate of progress KDeNo for the DeNO. regeneration can be expressed as a percentage of DeNO. regeneration per second, in symbols [%/s].

During the DeNO. regeneration, the time spent in such DeNOxpme is monitored and is multiplied by the DeNO. rate of progress KDeNox in order to calculate (block 520) a percentage DeNOxpem of the DeNO. regeneration performed When the percentage DeNOxpem of DeNO. regeneration performed reaches a predefined threshold value TargetDeNOxperc (block 525), the regeneration may be ended (block 530). 10 The predefined threshold value TargetDeNOxpert may be pre-determined on a test bench, by means of a calibration test, and stored in the memory system.

According to a further embodiment of the invention (shown in figure 5), in order to take into account the different effects of the aging of the LNT 285, the engine working point factor KvdrkPnt is expressed (block 540) as the output of a map that receives as input a first parameter indicative of a LNT 285 in a new condition (or clean, i.e. without NO trapped in the active sites thereof), see block 545, and a second parameter indicative of a LNT 285 in an aged condition (or full of trapped NOR), see block 550.

These two parameters are then interpolated using a LNT 285 ageing factor (block 555) representing the actual age of the LNT 285.

Moreover, the first parameter indicative of a LNT 285 in a new condition and the second parameter indicative of a LNT 285 in an aged condition are expressed as the output of respective maps, pre-calibrated on a test bench and stored in the memory system, that both receive as input an (actual) engine speed value and an (actual) engine torque value. Then, as in the previous embodiment, the DeNO. rate of progress KoeNox for the regeneration is determined (block 560) on the basis of the engine working point factor Kwapn, and of the regeneration factor KRgn of the LNT 285, this latter parameter being calculated (block 565), as in previous embodiment, as the output of a further map, pre-calibrated on a test bench and stored in the memory system, that receives as input a Lambda value measured by the only one Lambda sensor 433, and the value of a stored mass in the LNT 285 at the start of the regeneration. Also in this case, the DeNO. rate of progress for the regeneration KDeNox is determined by the formula: I<DeN0x = KatPnt * '<Hp (1) During the DeN0x regeneration, the time spent in such DeN0xtune is monitored and is multiplied by the DeNOx rate of progress Knorox in order to calculate (block 570) a percentage DeNOxpem of the DeN0x regeneration performed and when the percentage DeNOxpem of the DeN0x regeneration performed reaches a predefined threshold value TargetDeNOxperc (block 575), the regeneration may be ended (block 580).

Also this predefined threshold value TargetDeNOxpere may be pre-determined on a test bench, by means of a calibration test, and stored in the memory system.

In all cases, an optimal duration of a DeN0* regeneration is accurately defined.

While at least one exemplary embodiment has been presented in the foregoing summary and 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 in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one 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 as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS

100 automotive system internal combustion engine engine block cylinder cylinder head 135 camshaft piston crankshaft combustion chamber cam phaser 160 fuel injector fuel injection system fuel rail fuel pump fuel source 200 intake manifold 205 air intake duct 210 intake port 215 valves 220 port 225 exhaust manifold 230 turbocharger 240 compressor 245 turbocharger shaft 250 turbine 260 intercooler 270 exhaust gas aftertreatment system 275 exhaust gas line 276 exhaust gas pipe 277 first connector pipe 278 second connector pipe 280 aftertreatment devices 285 LNT 286 DPF 290 VGT 300 exhaust gas recirculation system 310 EGR cooler 320 EGR valve 330 throttle body 340 mass airflow, pressure, temperature 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant temperature and level sensors 385 lubricating oil temperature and level sensor 390 metal temperature sensor 400 fuel rail digital pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensors 431 first temperature sensor 432 second temperature sensor 433 Lambda sensor 440 EGR temperature sensor 445 accelerator position sensor 446 accelerator pedal 450 ECU/controller 500 block 510 block 515 block 520 block 525 block 530 block 540 block 545 block 550 block 555 block 560 block 565 block 570 block 575 block 580 block

Claims

CLAIMS1. An internal combustion engine (110) comprising an exhaust gas line (275), a Lean NOx Trap (285) disposed in the exhaust gas line (275), only one Lambda sensor (433) disposed in the exhaust gas line (275) upstream of the Lean NOx Trap (285), and a first and a second temperature sensor (431,732) disposed in the exhaust gas line (275), wherein a first temperature sensor (431) is disposed upstream of the Lean NO Trap (285) and a second temperature sensor (432) is disposed downstream of the Lean NOx Trap (285).
2. The internal combustion engine (110) according to claim 1, wherein a particulate filter (286) is disposed in the exhaust gas line (275) downstream of the Lean NO Trap (285).
3. The internal combustion engine (110) according to claim 2, wherein the exhaust gas line (275) comprises a first connector pipe (277) connecting an exhaust manifold (225) to an inlet of the Lean NO Trap (285) and a second connector pipe (278) connecting an outlet of the Lean NO Trap (285) to an inlet of the particulate filter (286).
4. The internal combustion engine (110) according to claim 3, wherein the only one Lambda sensor (433) is disposed in the first connector pipe (277).
S. The internal combustion engine (110) according to claim 3 or 4, wherein the first temperature sensor (431) is disposed in the first connector pipe (277) and the second temperature sensor (432) is disposed in the second connector pipe (278).
6. The internal combustion engine (110) according to any of the preceding claims, further comprising an electronic control unit (45)) configured to perform the steps of: starting a DeN0x regeneration of the Lean NO Trap, - monitoring an engine speed value, an engine torque value, and a Lambda value upstream of the Lean NOx Trap, - determining a DeN0x rate of progress for the DeN0x regeneration on the basis of the engine speed value, the engine torque value, the Lambda value and a value of a NO stored mass in the Lean NO Trap (285) at the start of the DeNO. regeneration, - monitoring an elapsed time value starting from the beginning of DeNO.regeneration, - multiplying the DeN0x rate of progress by the elapsed time value in order to calculate a percentage of the DeNO. regeneration performed, - ending the DeN0x regeneration when the percentage of the DeN0x regeneration performed reaches a predefined threshold value.
7. The internal combustion engine (110) according to claim 6, wherein the determination of the DeN0x rate of progress is performed by: using the engine speed value and the engine torque value to determine an engine working point factor indicative of the effect of the engine performance on the DeNO. rate of progress and -using the Lambda value upstream of the Lean NO Trap (285) and the value of the NO stored mass in the Lean NO Trap (285) at the start of the DeN0x regeneration to determine a regeneration factor of the Lean NO Trap (285) indicative of the effect of the Lean NO Trap parameters on the DeN0x rate of progress, and determining the DeN0x rate of progress on the basis of the engine working point factor and of the regeneration factor of the Lean NOx Trap (285).
8. The internal combustion engine according to claim 7, wherein the engine working point factor is expressed as an output value of a map that receives as an input an engine speed value and an engine torque value.
9. The internal combustion engine (110) according to claim 7, wherein the regeneration factor of the Lean NO. Trap (285) is expressed as an output value of a map that receives as an input a Lambda value measured upstream of the Lean NO, Trap (285) by the only one Lambda sensor (433) and a value of a NO, stored mass in the Lean NO. Trap (285) at the start of the DeNO, regeneration.
10. The internal combustion engine (110) according to claim 7, wherein the engine working point factor is calculated by: using a first map indicative of a new Lean NO, Trap (285), the first map receiving as an input an engine speed value and an engine torque value, - using a second map indicative of an aged Lean NO, Trap (285), the second map receiving as an input an engine speed value and an engine torque value, monitoring the actual age of the Lean NO, Trap (285) to determine an ageing factor of the Lean NO, Trap (285), and - calculating the engine working point factor by interpolation of the output values of the first and the second map taking into account the ageing factor of the Lean NO, Trap (285).
11. The internal combustion engine (110) according to any claim from 7 to 10, wherein the DeNO, rate of progress for the regeneration is determined according to the formula: KDeN0x = KwrkPnt * KRgn, in which: KDeN0x is the rate of progress for the regeneration, Kwrkprd is the engine working point factor and KR9n is the regeneration factor of the Lean NO Trap (285).
12. Automotive system (100) comprising an internal combustion engine (110) according to any of the preceding claims.