METHOD FOR CONTROLLING THE OPERATION OF AN ENGINE SYSTEM IN A VEHICLE

Abstract

A method for controlling the operation of an engine system in a vehicle. The engine system including an engine and an exhaust aftertreatment system having an SCR catalyst and a DPF. The method includes determining preview information of the vehicle operation based at least on an upcoming road event and an engine operation associated with the upcoming road event; performing, in response of the preview information, at least one of: controlling the operation of the engine system by increasing reductant injection to meet an ammonia storage threshold level; controlling the operation of the engine system by increasing the engine out NOx to reduce the ammonia storage in the SCR catalyst to meet an ammonia slip threshold level in the SCR catalyst; controlling the operation of the engine system by decreasing the engine out NOx to increase the amount of engine out particles to meet a soot threshold level in the DPF.

Claims

1. A method for controlling the operation of an engine system in a vehicle, the engine system comprising an engine and an exhaust aftertreatment system having a selective catalytic reduction, SCR, catalyst and a diesel particulate filter, DPF, the method comprising: determining preview information of the vehicle operation based at least on an upcoming road event and an engine operation associated with the upcoming road event; performing, in response of the preview information, at least one of the following: predicting an ammonia storage in the SCR catalyst at least partly based on the current level of ammonia storage in the SCR catalyst, and controlling the operation of the engine system by increasing reductant injection to meet an ammonia storage threshold level in response of predicting an ammonia storage in the SCR catalyst below the ammonia storage threshold level; predicting an ammonia slip out of the SCR catalyst, and controlling the operation of the engine system by increasing the engine out NOx to reduce the ammonia storage in the SCR catalyst to meet an ammonia slip threshold level in the SCR catalyst in response of predicting an ammonia slip above the ammonia slip threshold level; predicting a soot level in the DPF, and controlling the operation of the engine system by decreasing the engine out NOx to increase the amount of engine out particles to meet a soot threshold level in the DPF in response of predicting a soot level below the soot threshold level.

2. The method according to claim 1, wherein the preview information comprises predicted engine speed and/or predicted engine torque in response of the upcoming road event.

3. The method according to claim 1, wherein the vehicle is a hybrid vehicle comprising an electric machine for propelling the vehicle in addition to the engine.

4. The method according to claim 3, wherein the preview information comprises a predicted engine shut-off, and in response to the predicted engine shut-off the method comprising performing the step of increasing reductant injection to meet an ammonia storage threshold level in the SCR catalyst while preventing engine shut-off.

5. The method according to claim 4, further comprising: subsequently of meeting the ammonia storage threshold level in the SCR catalyst, enabling or performing engine shut-off.

6. The method according to claim 5, further comprising: propelling the vehicle with the electric machine and the engine off.

7. The method according to claim 1, wherein the preview information comprises a predicted thermal event resulting in a temperature in the exhaust aftertreatment system above a threshold temperature.

8. The method according to claim 7, wherein the threshold temperature corresponds to a temperature causing an ammonia slip out of the SCR catalyst above the ammonia slip threshold level, and in response to the predicted thermal event, performing the step of increasing the engine out NOx to reduce the ammonia storage in the SCR catalyst to meet the ammonia slip.

9. The method according to claim 7, wherein the threshold temperature corresponds to a temperature causing a regeneration of the DPF and a soot level below the soot threshold level, and in response to the predicted thermal event, performing the step of decreasing the engine out NOx to increase the amount of engine out particles to meet the soot threshold level.

10. The method according to claim 7, wherein the threshold temperature corresponds to a temperature causing the ammonia storage in the SCR catalyst to drop below the ammonia storage threshold level, and in response to the predicted thermal event, increasing reductant injection to meet the ammonia storage threshold level in the SCR.

11. A controlling apparatus for a vehicle comprising an engine system, the engine system comprising an engine and an exhaust aftertreatment system having an SCR catalyst and a DPF, the controlling apparatus being configured to: determine preview information of the vehicle operation based at least on an upcoming road event and an engine operation associated with the upcoming road event; and perform, in response of the determined preview information, at least one of the following: a prediction of an ammonia storage in the SCR catalyst at least partly based on the current level of ammonia storage in the SCR catalyst, and a control operation of increasing reductant injection to meet an ammonia storage threshold level in response of a prediction that the ammonia storage in the SCR catalyst is below the ammonia storage threshold level; a prediction of an ammonia slip out of the SCR catalyst, and a control operation to increase the engine out NOx to reduce the ammonia storage in the SCR catalyst to meet an ammonia slip threshold level in the SCR catalyst in response of a prediction that the ammonia slip is above the ammonia slip threshold level; a prediction of a soot level in the DPF, and a control operation to decrease the engine out NOx to increase the amount of engine out particles to meet a soot threshold level in the DPF in response of a prediction that the soot level is below the soot threshold level.

12. A vehicle comprising an engine system and a controlling apparatus according to claim 11, the engine system comprising an engine and an exhaust aftertreatment system having an SCR catalyst and a DPF.

13. The vehicle according to claim 12, being a hybrid vehicle comprising an electric machine for propelling the vehicle in addition to the engine.

14. The vehicle according to claim 12, wherein the DPF is arranged upstream of the SCR catalyst in the exhaust aftertreatment system.

15. A computer program comprising program code means for performing the method according to claim 1, when the program is run on a computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. In the drawings:

[0061] FIG. 1 is a schematic side view of a vehicle comprising an engine system and a controlling apparatus in accordance with an example embodiment of the invention;

[0062] FIG. 2A is a schematic perspective view of a vehicle traveling along a road with upcoming road events, applicable to example embodiments of the invention;

[0063] FIG. 2B shows a schematic example of preview information of the vehicle operation based on upcoming road events and associated engine operations, applicable to example embodiments of the invention; and

[0064] FIG. 3 is a flowchart illustrating the steps of a method in accordance with one example embodiment of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0065] With reference to FIG. 1 a vehicle 1, here embodied as a heavy duty truck 1, comprising an engine system 10 is disclosed for which a controlling apparatus 3 of a kind disclosed in the present disclosure is advantageous. However, the controlling apparatus 3 may as well be implemented in other types of vehicles, such as in busses, light-weight trucks, passenger cars, marine applications etc having similar engine systems. The vehicle 1 of FIG. 1 is a hybrid vehicle 1 comprising an engine 20, being a diesel engine 20, and an electric machine 22. The diesel engine 20 is powered by diesel fuel, typically comprised in a fuel tank (not shown) and the electric machine 22 is powered by electricity supplied from at least one energy storage or transformation device, e.g. a battery or a fuel cell. The diesel engine 20 and the electric machine 22 are typically arranged and configured to individually propel the vehicle 1, by being separately coupled to other parts of the powertrain of the vehicle 1, such as transmission, drive shafts and wheels (not shown in detail). That is, the vehicle 1 may be propelled by the diesel engine 20 alone, the electric machine 22 alone, or by the diesel engine 20 together with the electric machine 22.

[0066] In FIG. 1, at least the diesel engine 20 is comprised in an engine system 10, the engine system 10 further comprising an exhaust aftertreatment system 30 having an SCR catalyst 32 and a DPF 34. The DPF, or diesel particulate filter, 34 is arranged upstream of the SCR catalyst 32, and is arranged and configured to remove particles, i.e. diesel particulate matter or soot, from the exhaust gas of the diesel engine 20. The SCR catalyst 32 is arranged and configured to convert nitrogen oxides, also referred to as NOx, with the aid of a catalyst, into diatomic nitrogen (N2), and water (H2O) (and potentially carbon dioxide CO2). A reductant, typically anhydrous ammonia, aqueous ammonia or urea solution (commonly referred to as urea in the present disclosure), is added to engine exhausts and is absorbed onto the catalyst in the SCR catalyst 32.

[0067] The controlling apparatus 3 of the vehicle 1 is configured to control the operation of the engine system 10, i.e. at least the diesel engine 20 and the exhaust aftertreatment system 30, by means of preview information 100 of the vehicle operation based at least on an upcoming road event 110, 120, 130 and an engine operation 210, 220, 230 associated with the upcoming road event 110, 120, 130 which now will be further described with reference to FIGS. 2A-2B and FIG. 3.

[0068] In FIG. 2A, a vehicle 1, such as the hybrid vehicle 1 in FIG. 1, is travelling along a road 50 and is approaching a road curve 110 and uphill 120. Moreover, a parking lot 130, in which the vehicle 1 may park, is present further down the road 50 on the right hand side of vehicle 1. The road curve 110, the uphill 120 and parking lot 130 are examples of upcoming road events 110, 120, 130. The vehicle 1 may be configured to adapt the vehicle operation based on the upcoming road events 110, 120, 130. For example, by acknowledging the uphill 120, and e.g. the length and inclination of the uphill 120, a vehicle operation in which the gear is adapted (typically downshifting for increased engine torque) may be prepared and initiated prior to that the vehicle 1 reach the uphill 120. In other words, the vehicle operation is at least partly defined by the engine operation (here downshifting). In a corresponding manner, various upcoming road events may be associated with a corresponding engine operation. This is exemplified in FIG. 2B, in which the already discussed uphill 120 is associated with an engine operation of downshifting and increased engine torque 210, wherein the road curve 110 (e.g. being a steep road curve 110) is associated with an engine operation of reduced engine speed 220, and wherein the parking lot 130 is associated with an engine operation of engine shut-off 230 (the latter e.g. being comprised in an vehicle operation of vehicle off). Other upcoming road events may e.g. be a downhill with the associated engine operation of engine shut-off. For the latter, the electric machine may propel the vehicle.

[0069] The upcoming road events 110, 120, 130 and the engine operations 210, 220, 230 may be commonly referred to as preview information 100 of the vehicle. The upcoming road events 110, 120, 130 are typically acquired from map data (comprising topology data), and is related to the position of vehicle 1 by means of a GPS or other vehicle localization means. The engine operations 210, 220, 230 are typically related to the upcoming road events 110, 120, 130 by means of models and/or otherwise predicted and required engine operation, known to the skilled person.

[0070] Turning to the flowchart of FIG. 3, schematically illustrating steps of a method for controlling the operation of an engine system in a vehicle, such as the engine system 10 of vehicle 1 in FIG. 1. Thus, the engine system comprises an engine, e.g. diesel engine 20 in FIG. 1, and an exhaust aftertreatment system, e.g. exhaust aftertreatment system 30 in FIG. 1, having a selective catalytic reduction, SCR, catalyst, e.g. SCR catalyst 32 in FIG. 1, and a diesel particulate filter, DPF, e.g. DPF 34 in FIG. 1.

[0071] In a step S10, e.g. being a first step S10, preview information (as the preview information 100 of FIG. 2B) of the vehicle operation is determined. The preview information is based at least on an upcoming road event (as e.g. the upcoming road events 110, 120, 130 of FIGS. 2A-2B) and an engine operation (as e.g. the engine operations 210, 220, 230 of FIGS. 2B) associated with the upcoming road event.

[0072] In a step S20, e.g. being a second step S20, a choice between three various embodiments of performing a prediction and control of the engine system is made in response to the preview information determined in step S10. The three various embodiments will now be described in further detail.

[0073] In at least a first embodiment, an ammonia storage in the SCR catalyst is predicted in a step S30, e.g. being a first step S30 of the first embodiment. The predicted ammonia storage in the SCR catalyst is at least partly based on the current level of ammonia storage in the SCR catalyst.

[0074] In a step S40, being e.g. a second step S40 of the first embodiment, the operation of the engine system is controlled by a step S50, being e.g. a first sub-step S50 of the first embodiment, of increasing urea injection to meet an ammonia storage threshold level in response of predicting S30 an ammonia storage in the SCR catalyst below the ammonia storage threshold level. The step S50 is according to one embodiment carried out in response to a preview information in step S10 comprising a predicted engine shut-off (as e.g. the engine shut-off 230 in FIG. 2).

[0075] In a step S60, being e.g. a second sub-step S60 of the first embodiment, engine shut-off is prevented. That is, the engine or diesel engine is prevented from being shut-off, typically as long as the ammonia storage in the SCR catalyst is below the ammonia storage threshold level. In other words, in response to a predicted engine shut-off (from the determined preview information in step 510), the step S50 of increasing urea injection to meet an ammonia storage threshold level in the SCR catalyst is performed while preventing engine shut-off S60.

[0076] Subsequently of meeting the ammonia storage threshold level in the SCR catalyst, or based on a prediction that the ammonia storage threshold level in the SCR catalyst will be reached upon the engine shut-off (i.e. upon the occurrence of the engine shut-off with no active prevention of engine shut-off), the method may comprise a step S62, being e.g. a third sub-step S62 of the first embodiment, of enabling or performing engine shut-off. Thus, the engine is allowed to be shut-off as the ammonia storage in the SCR catalyst is sufficient.

[0077] According to at least one example embodiment, the vehicle is a hybrid vehicle comprising an electric machine (as e.g. the electric machine 22 in FIG. 1) arranged and configured to propel the vehicle in addition to the engine. Thus, subsequent to performing engine shut-off S62, the method may comprise a step S64, being e.g. a fourth sub-step S64 of the first embodiment, of propelling the vehicle with the electric machine and the engine off.

[0078] As shown in FIG. 3, the first, second, third and fourth sub-steps, S50, S60, S62, S64 may be comprised in the step S40 of controlling the operation of the engine system. Moreover, the steps S60, S62 and S64 are optional, which is indicated by dashed line boxes in FIG. 3.

[0079] In at least a second embodiment, an ammonia slip out of the SCR catalyst is predicted in a step S32, e.g. being a first step S32 of the second embodiment.

[0080] In a step S42, being e.g. a second step S42 of the second embodiment, the operation of the engine system is controlled by a step S52, being e.g. a first sub-step S52 of the second embodiment, of increasing the engine out NOx to reduce the ammonia storage in the SCR catalyst to meet an ammonia slip threshold level in the SCR catalyst in response of predicting an ammonia slip above the ammonia slip threshold level.

[0081] The step S52 is according to one embodiment carried out in response to a preview information in step S10 comprising a predicted thermal event (as e.g. the predicted thermal event 220 in FIG. 2) resulting in a temperature in the exhaust aftertreatment system above a threshold temperature. The step S52 is typically carried out in response of a threshold temperature corresponding to a temperature causing an ammonia slip out of the SCR catalyst above the ammonia slip threshold level. In other words, in response to a predicted thermal event, the step 52 of increasing the engine out NOx to reduce the ammonia storage in the SCR catalyst to meet the ammonia slip, is performed.

[0082] In at least a third embodiment, a soot level in the DPF is predicted in a step S34, e.g. being a first step S34 of the third embodiment.

[0083] In a step S44, being e.g. a second step S44 of the third embodiment, the operation of the engine system is controlled by a step S54, being e.g. a first sub-step S54 of the third embodiment, of decreasing the engine out NOx to increase the amount of engine out particles to meet a soot threshold level in the DPF in response of predicting a soot level below the soot threshold level.

[0084] The step S54 is according to one embodiment carried out in response to a preview information in step 510 comprising a predicted thermal event (as e.g. the predicted thermal event 220 in FIG. 2) resulting in a temperature in the exhaust aftertreatment system above a threshold temperature. The step S54 is typically carried out in response of a threshold temperature corresponding to a temperature causing a regeneration of the DPF and a soot level below the soot threshold level. In other words, in response to a predicted thermal event, the step 54 of decreasing the engine out NOx to increase the amount of engine out particles to meet a soot threshold level in the DPF in response of predicting a soot level below the soot threshold level, is performed.

[0085] As an alternative fourth embodiment, the step S50 is carried out in response to a preview information in step S10 comprising a thermal event. In other words, in response to a predicted thermal event, the steps S20, S30, S40 and S50 of increasing urea injection to meet the ammonia storage threshold level in the SCR, is performed.

[0086] According to at least one example embodiment, the steps of the method according to the first, second, third and fourth embodiments, may be combined and performed subsequently of each other. It should be noted that the naming of the steps not necessarily, but might according to at least one example embodiment, relate to the order in which the steps are carried out. Thus, the order of the steps may be different than that explained here, unless explicitly being dependent on each other.

[0087] Turning back to FIGS. 1, 2A and 2B, the controlling apparatus 3 of vehicle 1 may be configured to carry out one or more of the steps of the method described with reference to FIG. 3. For example, the controlling apparatus 3 may be a computer comprising a computer program comprising program code means for performing the method according to one or more of the steps described with reference to FIG. 3.

[0088] In other words, the controlling apparatus 3 is at least configured to: [0089] determine preview information 100 of the vehicle operation based at least on an upcoming road event 110, 120, 130 and an engine operation 210, 220, 230 associated with the upcoming road event 110, 120, 130; and [0090] perform, in response of the determined preview information 100, at least one of the following: [0091] a prediction of an ammonia storage in the SCR catalyst 32 at least partly based on the current level of ammonia storage in the SCR catalyst 32, and a control operation of the engine system 10 of increasing urea injection to meet an ammonia storage threshold level in response of a prediction that the ammonia storage in the SCR catalyst 32 is below the ammonia storage threshold level (i.e. as described with reference to steps S30, S40 and S50 of FIG. 3); [0092] a prediction of an ammonia slip out of the SCR catalyst 32, and a control operation of the engine system 10 to increase the engine out NOx to reduce the ammonia storage in the SCR catalyst 32 to meet an ammonia slip threshold level in the SCR catalyst 32 in response of a prediction that the ammonia slip is above the ammonia slip threshold level (i.e. as described with reference to steps S32, S42 and S52 of FIG. 3); [0093] a prediction of a soot level in the DPF 34, and a control operation of the engine system 10 to decrease the engine out NOx to increase the amount of engine out particles to meet a soot threshold level in the DPF 34 in response of a prediction that the soot level is below the soot threshold level (i.e. as described with reference to steps S34, S44 and S54 of FIG. 3).

[0094] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

[0095] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed inventive concept, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.