Patent Application
20160177859
This application claims priority to Great Britain Patent Application No. 1422613.8, filed Dec. 18, 2014, which is incorporated herein by reference in its entirety.
The present disclosure pertains to a method of operating an internal combustion engine, typically an internal combustion engine of a motor vehicle, such as a diesel engine or a gasoline engine. More specifically, the present disclosure relates to a method of operating the internal combustion engine in order to quickly and effectively warm up an engine aftertreatment system.
It is known that modern internal combustion engines are equipped with an aftertreatment system comprising one or more aftertreatment devices which are disposed in the exhaust pipe to change the composition of the exhaust gases, thereby reducing the polluting emissions of the engine.
Some examples of aftertreatment devices include catalytic converters (two and three ways), oxidation catalysts, lean NOx traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters.
In order to reduce the emissions of nitrogen oxides (NOx), some internal combustion engines may be also equipped with an exhaust gas recirculation (EGR) system, which is provided for routing back part of the exhaust gas produced by the engine from the exhaust manifold into the intake manifold.
Many aftertreatment devices are generally characterized by a so called “light off” temperature, below which the efficiency of these aftertreatment devices is quite low and they are not always able to achieve the emission reduction targets required by the current legislations.
This side effect particularly occurs when the aftertreatment devices are aged due a prolonged use, so that it is generally necessary to try to prevent this performance reduction by correspondently increasing the quantity of Platinum Group Metals (PGM) inside the aftertreatment devices.
In addition, it is generally necessary to try to accelerate as much as possible the warm up of the aftertreatment devices by overusing other devices capable of heating the engine, such as for example the glow plugs that are conventionally located in the engine cylinders.
In view of the above, in accordance with embodiments of the present disclosure provided are strategies for warming up the aftertreatment system of an engine, which are capable of reducing the time necessary for the aftertreatment devices to reach their light off temperature, thereby allowing both new and aged devices to meet the emission reduction targets more effectively.
Advantageously provided by the herein described embodiments, the goal is reached with a simple, rational and rather inexpensive solution.
More particularly, an embodiment of the invention provides a method of operating an internal combustion engine executing a warm up strategy of an engine aftertreatment system, wherein the warm up strategy may include injecting fuel into the engine according to a multi-injection pattern including at least one after injection.
An after injection is an injection of fuel that is performed inside the engine cylinder after the piston has passed the top death center (TDC) position but before the opening of the exhaust valve. The quantity of fuel supplied by means of an after injection, which is normally a small quantity (e.g. 1 mm3), has a negligible impact on the torque generated by the engine but actually burns inside the cylinder, thereby increasing the temperature of the exhaust gases that, after the opening of the exhaust valve, will flow through the aftertreatment system.
In this ways, the overheated exhaust gas increases the temperature of the aftertreatment system, whose devices can thus reach faster the light off temperature and become quickly efficient even when they are aged.
By reducing the warm up time, the proposed strategy has also the advantages of preventing other components (such as the glow plugs) from being overused and of allowing the adoption of aftertreatment devices having a reduced quantity of Platinum Group Metals (PGM), thereby achieving an overall reduction of the cost related to the aftertreatment system.
In addition, the combustion of the fuel provided by the after injection attains also a faster warm up of the engine bodies, such as the engine block and the cylinder head, along with all the engine fluids that circulates inside them, such as the engine coolant and engine lubricant, thereby achieving other secondary benefits.
For example, by accelerating the engine coolant warm up, the proposed strategy makes it possible to heat faster the cabin of the vehicle, thereby increasing the comfort for the driver and the passengers especially when they use the vehicle under very cold environmental conditions.
According to an aspect of the invention, the multi-injection pattern may include a plurality of after injections (e.g. up to four after injections per engine cycle).
By using a plurality of after injections (i.e. a multi-after-injection pattern) instead of a single after injection, all the benefits mentioned above can be enhanced and favorably optimized.
In addition, a multi-after-injection pattern is capable of supporting the combustion within the engine cylinder, thereby reducing the production of hydrocarbon (HC) and obtaining a better stability of the engine.
According to another aspect of the invention, the multi-injection pattern may include at least one post injection.
A post injection is an injection of fuel that is performed inside the engine cylinder after the opening of the exhaust valve. The quantity of fuel supplied by means of a post injection, which is normally a small quantity (e.g. 1 mm3), does not burn inside the cylinder but is discharged unburnt through the exhaust valve. As a matter of fact, this quantity of fuel burns along the exhaust line or within the oxidation catalyst (e.g. DOCs) on its path, thereby locally producing hot exhaust gases that are able to heat the aftertreatment system.
By using at least one post injection, the proposed strategy is thus able to warm up also aftertreatment devices that are located relatively far from the engine, such as selective catalytic reduction (SCR) catalysts.
An aspect of the invention provides that the multi-injection pattern may include a plurality of post injections.
By using a plurality of post injections (i.e. a multi-post-injection pattern) instead of a single post injection, the benefit mentioned above can be enhanced.
According to another aspect of the invention, the warm up strategy may further comprise allowing a recirculation of exhaust gas from an exhaust manifold to an intake manifold of the engine.
Thanks to this aspect of the invention, while the fuel injection is performed according to the multi-injection pattern disclosed above, it is also possible to reduce the amount of nitrogen oxides (NOx) produced by the engine, thereby contributing to reduce the polluting emission even during the execution of the warm up strategy.
An aspect of the invention provides that the warm up strategy may be executed if (i.e. only if) an exhaust gas temperature at an inlet of a particulate filter of the aftertreatment system is below a predetermined threshold value thereof.
This aspect makes it possible to activate the warm up strategy only if the aftertreatment system is actually cold.
Another aspect of the invention provides that the warm up strategy may be executed if (i.e. only if) an engine coolant temperature is below a predetermined threshold value thereof.
This aspect makes it possible to activate the warm up strategy only if the engine is actually cold.
Still another aspect of the invention provides that the warm up strategy may be executed if (i.e. only if) an engine speed is below a predetermined threshold value thereof.
This aspect of the invention is based on the fact that, when the engine speed exceeds a given threshold value, the temperature of the exhaust gas produced by the engine is generally high enough to effectively heat the aftertreatment system, without the need of performing after injections and/or post injections. As a consequence, this aspect of the invention has the effect of preventing an unnecessary consumption of fuel.
According to another aspect of the invention, the warm up strategy may be executed if (i.e. only if) an engine load (e.g. the quantity of fuel globally injected per engine cycle) is below a predetermined threshold value thereof.
This aspect of the invention is based on the fact that, when the engine load exceeds a given threshold value, the temperature of the exhaust gas produced by the engine is generally high enough to effectively heat the aftertreatment system, without the need of performing after injections and/or post injections. As for the preceding case, also this aspect of the invention has thus the effect of preventing an unnecessary consumption of fuel.
Another aspect of the invention provides that the warm up strategy may be executed if (i.e. only if) a predetermined gear of an engine gear box is engaged.
This aspect of the invention provides an additional degree of freedom that allows to activate the warm up strategy only if it is strictly needed to raise the temperature of the aftertreatment system.
According to still another aspect of the invention, the warm up strategy may be executed if (i.e. only if) an ambient pressure and an ambient temperature are both below a predetermined threshold value thereof.
This aspect allows to activate the warm up strategy only if the engine is operated under environmental conditions that actually requires for the aftertreatment system to be heated.
A further aspect of the invention provides that the warm up strategy may be deactivated after a predetermined time after its activation.
This aspect allows to achieve a favorable trade-off between the warm up speed and the fuel consumption.
The method of the invention can be carried out with the help of a computer program comprising a program-code for carrying out the method described above, and in the form of a computer program product comprising the computer program. The method can be also embodied as an electromagnetic signal, said signal being modulated to carry a sequence of data bits which represent a computer program to carry the method.
Another embodiment of the invention provides an internal combustion engine equipped with an electronic control unit configured to execute a warm up strategy of an engine aftertreatment system, wherein the warm up strategy comprises injecting fuel into the engine according to a multi-injection pattern including at least one after injection.
This embodiment of the invention achieves the same benefits disclosed in relation to the method, in particular that of allowing the aftertreatment devices of the aftertreatment system to reach faster their light off temperature and become quickly efficient even when they are aged.
According to an aspect of the invention, the multi-injection pattern may include a plurality of after injections (e.g. up to four after injections per engine cycle).
By using a plurality of after injections (i.e. a multi-after-injection pattern) instead of a single after injection, all the benefits mentioned above can be enhanced and favorably optimized, while obtaining also a reduction in the production of hydrocarbon (HC) and a better stability of the engine.
According to another aspect of the invention, the multi-injection pattern may include at least one post injection.
By using at least one post injection, it is possible to warm up also aftertreatment devices that are located relatively far from the engine, such as selective catalytic reduction (SCR) catalysts.
An aspect of the invention provides that the multi-injection pattern may include a plurality of post injections.
By using a plurality of post injections (i.e. a multi-post-injection pattern) instead of a single post injection, the benefit mentioned above can be enhanced.
According to another aspect of the invention, the warm up strategy may further comprise allowing a recirculation of exhaust gas from an exhaust manifold to an intake manifold of the engine.
According to this embodiment, while the fuel injection is performed according to the multi-injection pattern disclosed above, it is also possible to reduce the amount of nitrogen oxides (NOx) produced by the engine.
An aspect of the invention provides that the electronic control unit may be configured to execute the warm up strategy if (i.e. only if) an exhaust gas temperature at an inlet of a particulate filter of the aftertreatment system is below a predetermined threshold value thereof.
This aspect makes it possible to activate the warm up strategy only if the aftertreatment system is actually cold.
Another aspect of the invention provides that the electronic control unit may be configured to execute the warm up strategy if (i.e. only if) an engine coolant temperature is below a predetermined threshold value thereof.
This aspect makes it possible to activate the warm up strategy only if the engine is actually cold.
Still another aspect of the invention provides that the electronic control unit may be configured to execute the warm up strategy if (i.e. only if) an engine speed is below a predetermined threshold value thereof.
This aspect of the invention has the effect of preventing an unnecessary consumption of fuel.
According to another aspect of the invention, the electronic control unit may be configured to execute the warm up strategy if (i.e. only if) an engine load (e.g. the quantity of fuel globally injected per engine cycle) is below a predetermined threshold value thereof.
Also this aspect of the invention has the effect of preventing an unnecessary consumption of fuel.
Another aspect of the invention provides that the electronic control unit may be configured to execute the warm up strategy if (i.e. only if) a predetermined gear of an engine gear box is engaged.
This aspect of the invention provides an additional degree of freedom that allows to activate the warm up strategy only if it is strictly needed to raise the temperature of the aftertreatment system.
According to still another aspect of the invention, the electronic control unit may be configured to execute the warm up strategy if (i.e. only if) an ambient pressure and an ambient temperature are both below a predetermined threshold value thereof.
This aspect allows to activate the warm up strategy only if the engine is operated under environmental conditions that actually requires for the aftertreatment system to be heated.
A further aspect of the invention provides that the electronic control unit may be configured to deactivate the warm up strategy after a predetermined time after its activation.
This aspect allows to achieve a favorable trade-off between the warm up speed and the fuel consumption.
Another embodiment of the invention provides an automotive system comprising an internal combustion engine and means for executing a warm up strategy of an engine aftertreatment system, wherein the means for executing the warm up strategy comprise means for injecting fuel into the engine according to a multi-injection pattern including at least one after injection.
This embodiment of the invention achieves the same benefits disclosed in relation to the method, in particular that of allowing the aftertreatment devices of the aftertreatment system to reach faster their light off temperature and become quickly efficient even when they are aged.
According to an aspect of the invention, the multi-injection pattern may include a plurality of after injections (e.g. up to four after injections per engine cycle).
By using a plurality of after injections (i.e. a multi-after-injection pattern) instead of a single after injection, all the benefits mentioned above can be enhanced and favorably optimized, while obtaining also a reduction in the production of hydrocarbon (HC) and a better stability of the engine.
According to another aspect of the invention, the multi-injection pattern may include at least one post injection.
By using at least one post injection, it is possible to warm up also aftertreatment devices that are located relatively far from the engine, such as selective catalytic reduction (SCR) catalysts.
An aspect of the invention provides that the multi-injection pattern may include a plurality of post injections.
By using a plurality of post injections (i.e. a multi-post-injection pattern) instead of a single post injection, the benefit mentioned above can be enhanced.
According to another aspect of the invention, the means for executing the warm up strategy may further comprise means for allowing a recirculation of exhaust gas from an exhaust manifold to an intake manifold of the engine.
Thanks to this aspect of the invention, while the fuel injection is performed according to the multi-injection pattern disclosed above, it is also possible to reduce the amount of nitrogen oxides (NOx) produced by the engine.
An aspect of the invention provides that the means for executing the warm up strategy may be configured to operate if (i.e. only if) an exhaust gas temperature at an inlet of a particulate filter of the aftertreatment system is below a predetermined threshold value thereof.
This aspect makes it possible to activate the warm up strategy only if the aftertreatment system is actually cold.
Another aspect of the invention provides that the means for executing the warm up strategy may be configured to operate if (i.e. only if) an engine coolant temperature is below a predetermined threshold value thereof.
This aspect makes it possible to activate the warm up strategy only if the engine is actually cold.
Still another aspect of the invention provides that the means for executing the warm up strategy may be configured to operate if (i.e. only if) an engine speed is below a predetermined threshold value thereof.
This aspect of the invention has the effect of preventing an unnecessary consumption of fuel.
According to another aspect of the invention, the means for executing the warm up strategy may be configured to operate if (i.e. only if) an engine load (e.g. the quantity of fuel globally injected per engine cycle) is below a predetermined threshold value thereof.
Also this aspect of the invention has the effect of preventing an unnecessary consumption of fuel.
Another aspect of the invention provides that the means for executing the warm up strategy may be configured to operate if (i.e. only if) a predetermined gear of an engine gear box is engaged.
This aspect of the invention provides an additional degree of freedom that allows to activate the warm up strategy only if it is strictly needed to raise the temperature of the aftertreatment system.
According to still another aspect of the invention, the means for executing the warm up strategy may be configured to operate if (i.e. only if) an ambient pressure and an ambient temperature are both below a predetermined threshold value thereof.
This aspect allows to activate the warm up strategy only if the engine is operated under environmental conditions that actually requires for the aftertreatment system to be heated.
A further aspect of the invention provides that the means for executing the warm up strategy may be configured to deactivate the warm up strategy after a predetermined time after its activation.
This aspect allows to achieve a favorable trade-off between the warm up speed and the fuel consumption.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.
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.
Some embodiments may include an automotive system 100, as shown in
The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake pipe 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 intake pipe 205 and manifold 200. An intercooler 260 disposed in the intake pipe 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 vanes prior to expansion through the turbine 250. 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 valve.
Some embodiments may comprise an exhaust gas recirculation (EGR) system 300 including an EGR conduit 305 that fluidly connects the outlet of the exhaust manifold 225 with the inlet of the intake manifold 200, thereby allowing part of the exhaust gas to be mixed with the comburent air. The EGR system 300 may further include an EGR cooler 310 located in the EGR conduit 305 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 may be provided for regulating the flow rate of exhaust gases in the EGR conduit 305.
Downstream of the turbine 250, the exhaust gases are directed into an aftertreatment system 270. The aftertreatment system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices. The aftertreatment devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NOx traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters.
In the embodiment of
In other embodiments (specially for 8-cylinder engines), the aftertreatment system 270 may comprise a diesel oxidation catalyst (DOC) 600 located in the exhaust pipe 275 in proximity of the turbine 250, as shown in
In still other embodiments, the aftertreatment system 270 may comprise a diesel oxidation catalyst (DOC) 700 located in the exhaust pipe 275 in proximity of the turbine 250 and a DPF 705 located in the exhaust pipe 275 downstream of the DOC 700, as shown in
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 (see
Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) 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 460, and send and receive signals to/from the interface bus. The memory system 460 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 methods and control the ICE 110.
The program stored in the memory system 460 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 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 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.
One of the tasks of the ECU 450 is that of operating each fuel injectors 160, in order to supply the fuel into the corresponding combustion chamber 150. In general, for any engine cycle, the fuel injector 160 may be operated so as to perform a single fuel injection or, more often, to perform a plurality of subsequent fuel injections (also referred as injection pulses) according to a predetermined multi-injection pattern.
The multi-injection pattern usually includes a so called main fuel injection, which is performed shortly before the piston 140 reaches the top death center position (TDC) at the end of the compression stroke. The main fuel injection supplies a relatively big quantity of fuel, which is able to generate, at the crankshaft 145, a torque corresponding to the demand of the driver.
The multi-injection pattern may also comprise one or more pilot injections, which are performed during the compression stroke of the piston 140, just before the main injection. The quantity of fuel supplied by means of each pilot injection is normally a small quantity, for example of about 1 mm3 of fuel, and has the effect of reducing the explosiveness of the main injection and thus the vibration of the engine 110.
The multi-injection pattern may also comprise one or more after injections. An after injection is an injection of fuel that is performed inside the combustion chamber 150 after the piston 140 has passed the top death position (TDC) at the beginning of the expansion stroke, but before the opening of the exhaust port 220. The quantity of fuel supplied by means of an after injection, which is normally a small quantity (e.g. 1 mm3), has a negligible impact on the torque generated by the engine but burns inside the combustion chamber 150, thereby increasing the temperature of the exhaust gases that, after the opening of the exhaust port 220, will flow towards the aftertreatment system 270.
The multi-injection pattern may also comprise one or more post injections. A post injection is an injection of fuel that is performed inside the combustion chamber 150 after the opening of the exhaust port 220 at the end of the expansion stroke. The quantity of fuel supplied by means of a post injection, which is normally a small quantity (e.g. 1 mm3), does not burn inside the combustion chamber 150 but is discharged unburnt through the exhaust port 220 towards the aftertreatment system 270. As a matter of fact, this quantity of fuel may burn along the exhaust pipe 275 or within the aftertreatment devices, thereby producing hot exhaust gases that are able to locally heat such devices.
According to conventional control strategies, the ECU 450 is generally configured to perform a multi-injection pattern having after injections and post injections, only during the regeneration of the particulate filter 505 (or 620 or 705 depending on the layout of the aftertreatment system 270).
However, according to an aspect of the present disclosure, the ECU 450 may be also configured to take advantage of the heating effect of the after injections and possibly of the pilot injections, in order to speed up the warm up of the aftertreatment system 270 after the start of the engine 110 and/or under other predetermined conditions, thereby reaching faster the light off temperature of the aftertreatment devices and thus improving their efficiency.
In other words, the ECU 450 may be configured to selectively activate a warm up strategy (block S100 of
An explanatory multi-injection pattern of this kind is represented in
Thanks to the after injections that burn inside the combustion chambers 150, the exhaust gas that exit the exhaust ports 220 is overheated and is able to increase the temperature of aftertreatment system 270, whose devices can thus reach faster the light off temperature and become quickly efficient even when they are aged.
However, since the temperature of the exhaust gas emitted by the engine 110 progressively decreases along the exhaust pipe 275, this solution is specially effective for heating the aftertreatment devices that are relatively close to the engine 110, such as the LNT-DOC 500 of the aftertreatment system 270 represented in
For this reason, an aspect of the present disclosure provides that the multi-injection pattern performed during the execution of the warm up strategy may also include one or more post injections, normally not more than two post injections.
An explanatory multi-injection pattern of this second kind is represented in
In addition to the heating effect produced by the after injections, the quantity of fuel provided by the post injections burns along the exhaust pipe 275 and/or within the DOCs, so that the resulting exhaust gases are effectively able to heat the aftertreatment devices that are located relatively far from the engine 110, such as the SCR catalyst 605 of the aftertreatment systems 270 of
While operating the fuel injection according to the multi-injection pattern disclosed above, the warm up strategy S100 may also comprise allowing a recirculation of exhaust gas from the exhaust manifold 225 to the intake manifold 200 of the engine 110 (block S110 of
To obtain this recirculation, the ECU 450 may be configured to operate the EGR valve 320 in order to open at least partially the EGR conduit 305, thereby letting the exhaust gas pass therein. The quantity of recirculated exhaust gas may be regulated by the ECU 450 according to conventional strategies, in order to reduce the quantity of nitrogen oxides (NOx) generated by the engine 110.
According to another aspect of the present disclosure, the warm up strategy S100 may be activated and executed only if certain predetermined conditions are fulfilled, for example according to the activation/deactivation logic represented in the flowchart of
First of all, the activation/deactivation logic may provide for the ECU 450 to monitor the value of one or more engine operating parameters. In particular, the ECU 450 may be configured to monitor the value TDPF of the exhaust gas temperature at the inlet of the DPF (block S200). Considering the aftertreatment system 270 of
The ECU 450 may be also configured to monitor the value Tcool of the engine coolant (block S205), for example by means of the sensor 380.
In addition, the ECU 450 may be also configured to monitor the value V of the engine speed (block S210), for example by means of the crank position sensor 420, and the value L of the engine load (block S215), namely the torque requested at the crankshaft 145 or correspondently the quantity of fuel to be injected inside the combustion chambers 150 to generate said torque. The value L of the engine load may be determined by the ECU 450 on the basis of the position of the accelerator pedal as measured by the sensor 445.
The ECU 450 may be further configured to monitor the gear N engaged in the gear box 147 (block S220), for example by means of the sensor 430, the value Tamb of the ambient temperature (block S225) and the value Pamb of the ambient pressure (block S230). The values Tamb and Pamb may be measured by the ECU 450 with dedicated sensors (not shown).
While monitoring these parameters, the ECU 450 may be configured to activate the warm up strategy (block S300) only if all the conditions set forth below are contemporaneously met.
A first condition may provide that the value TDPF of the exhaust gas temperature at the inlet of the DPF is below a predetermined threshold value TDPF,th1 thereof (block S235). The threshold value TDPF,th1 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the threshold value TDPF,th1 may be any value lower than 250° C., in particular it may be set at 220° C. More particularly, the first condition may provide that the value TDPF of the exhaust gas temperature at the inlet of the DPF is comprised between the threshold value TDPF,th1 and a second predetermined threshold value TDPF,th2, which is lower than the first one. Also this second threshold value TDPF,th2 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the second threshold value TDPF,th2 may be set at 16° C.
A second condition may provide that the value Tcool of the engine coolant temperature is below a predetermined threshold value Tcool, th1 thereof (block S240). The threshold value Tcool,th1 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the threshold value Tcool,th1 may be any value lower than 50° C., in particular it may be set at 40° C. More particularly, the second condition may provide that the value Tcool of the engine coolant temperature is comprised between the threshold value Tcool,th1 and a second predetermined threshold value Tcool,th2 which is lower than the first one. Also this second threshold value Tcool,th2 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the second threshold value Tcool,th2 may be set at 16° C.
A third condition may provide that the value V of the engine speed is below a predetermined threshold value Vth1 thereof (block S245). The threshold value Vth1 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the threshold value Vth1 may be any value lower than 3000 rpm (round per minute), in particular it may be set at 2750 rpm. More particularly, the third condition may provide that the value V of the engine speed is comprised between the threshold value Vth1 and a second predetermined threshold value Vth2, which is lower than the first one. This second threshold value TDPF,th2 may correspond to the idle speed of the engine 110 and may be set for example at 850 rpm.
A fourth condition may provide that the value L of the engine load is below a predetermined threshold value Lth thereof (block S250). The threshold value Lth may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the threshold value Lth may be any value comprised between 40 and 50 mm3.
A fifth condition may provide that the gear N engaged in the gearbox 147 corresponds to a predetermined one Nth (block S255). The predetermined gear Nth may be chosen on the basis of theoretical considerations. By way of example, the predetermined gear Nth may be the second gear.
A sixth condition may provide that the value Tamb of the ambient temperature is below a predetermined threshold value Tamb,th1 thereof (block S260). The threshold value Tamb,th1 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the threshold value Tamb,th1 may be any value lower than 40° C., in particular it may be set at 32° C. More particularly, the sixth condition may provide that the value Tamb of the ambient temperature is comprised between the threshold value Tamb,th1 and a second predetermined threshold value Tamb,th2, which is lower than the first one. Also this second threshold value Tamb,th2 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the second threshold value Tamb,th2 may be set at 16° C.
An seventh condition may provide that the value Pamb of the ambient pressure is below a predetermined threshold value Pamb,th1 thereof (block S265). The threshold value Pamb,th1 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the threshold value Pamb,th1 may be any value lower than 110 KPa, in particular it may be set at 105 KPa. More particularly, the seventh condition may provide that the value Pamb of the ambient pressure is comprised between the threshold value Pamb,th1 and a second predetermined threshold value Pamb,th2, which is lower than the first one. Also this second threshold value Pamb,th2 may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations. By way of example, the second threshold value Pamb,th2 may be set at 91 KPa.
Once the warm up strategy has been activated, it may be executed as long as all the above mentioned conditions are still fulfilled. As soon as at least one of the conditions is no more fulfilled, the warm up strategy may be deactivated (block S305) and the engine 110 may be operated according to conventional fuel injection strategies. By way of example, the warm up strategy may be deactivated when the value TDPF of the exhaust gas temperature at the DPF inlet exceeds the threshold value TDPF,th1 or when the value Tcool of the engine coolant temperature exceeds the threshold value Tcool,th1, because it generally means that the aftertreatment system 270 and/or the engine 110 has/have been already warmed up.
In addition or as an alternative, a timer (block S310) may be provided for counting the time te1 that elapses from the activation of the warm up strategy. In this way, the warm up strategy may be deactivated as soon as said time te1 reaches a predetermined value te1,th thereof (block S315). The threshold value te1,th may be a calibration parameter that may be determined by means of an experimental activity and/or based on theoretical considerations, in order to achieve a favourable trade-off between the warm up speed and the fuel consumption. By way of example, the threshold value te1,th may be any value lower than 50 s (seconds), in particular it may be set at 35 s.
Even if the preceding disclosure provides that the warm up strategy is activated and executed only if all the conditions set forth above are satisfied, other embodiments may provide for the warm up strategy to be activated and executed when only one (or a limited group) of said conditions is satisfied. By way of example, the warm up strategy may be activated and executed provided that only the first condition (related to the exhaust gas temperature) and/or the second condition (related to the coolant temperature) is/are satisfied.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1422613.8 | Dec 2014 | GB | national |
