A METHOD FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE ARRANGEMENT

Abstract

The present invention relates to a method for controlling an internal combustion engine arrangement (100) connected to an exhaust gas aftertreatment system (200), wherein the method is arranged to control a gas heating device ( 122), as well as a gas feeding arrangement to direct a flow of intake air through the exhaust gas recirculation conduit (112) from the intake system to the exhaust system, the flow of intake air being directed through the gas heating device before the intake air enters the exhaust gas aftertreatment system, in response to determining a requested start of the internal combustion engine to heat the aftertreatment system before starting the engine.

Claims

1. A method for controlling an internal combustion engine arrangement connected to an exhaust gas aftertreatment system, the internal combustion engine arrangement comprising an internal combustion engine comprising a plurality of combustion cylinders; an intake system arranged in upstream fluid communication with the internal combustion engine and configured to feed intake air into the plurality of combustion cylinders; an exhaust system arranged in downstream fluid communication with the internal combustion engine and configured to convey exhaust gas away from the internal combustion engine to the exhaust gas aftertreatment system; an exhaust gas recirculation system comprising an exhaust gas recirculation conduit connected between the intake system and the exhaust system, wherein the internal combustion engine arrangement further comprises a gas feeding arrangement and a gas heating device, each arranged in fluid communication with the exhaust gas recirculation conduit, the method comprising: determining a requested start of the internal combustion engine; controlling start up of the gas heating device for initiating heating of gas fed there through; and controlling the gas feeding arrangement to direct a flow of intake air through the exhaust gas recirculation conduit from the intake system to the exhaust system, the flow of intake air being directed through the gas heating device before the intake air enters the exhaust gas aftertreatment system.

2. The method according to claim 1, wherein the steps of controlling start up of the gas heating device and controlling the gas feeding arrangement to direct the flow of intake air to the exhaust system is executed prior to starting the internal combustion engine.

3. The method according to claim 1, further comprising the step of: receiving a signal indicative of a temperature level of the internal combustion engine arrangement; and controlling the gas feeding arrangement proportionally to the temperature level.

4. The method according to claim 1, further comprising the steps of: determining a temperature level of the internal combustion engine arrangement; comparing the temperature level with a predetermined temperature threshold limit; and controlling start up of the gas heating device and controlling the gas feeding arrangement to direct the flow of intake air to the exhaust system only if the temperature level is below the predetermined temperature threshold limit.

5. The method according to claim 4, wherein the temperature level of the internal combustion engine arrangement corresponds to a temperature level of the internal combustion engine, and the predetermined temperature threshold limit corresponds to a predetermined engine temperature level.

6. The method according to claim 4, wherein the temperature level of the internal combustion engine arrangement corresponds to a temperature level of the exhaust gas aftertreatment system, and the predetermined temperature threshold limit corresponds to a predetermined exhaust gas aftertreatment system temperature threshold limit.

7. The method according to claim 4, wherein the temperature level of the internal combustion engine arrangement corresponds to a temperature level in the exhaust gas recirculation conduit, and the predetermined temperature threshold limit corresponds to a predetermined temperature threshold limit for the exhaust gas recirculation conduit.

8. The method according to claim 1, wherein the gas feeding arrangement comprises a gas flow pump.

9. The method according to claim 8, wherein the gas flow pump is a bidirectional gas flow pump arranged to controllably direct gas flow from the exhaust system to the intake system, and from the intake system to the exhaust system.

10. The method according to claim 8, wherein the gas feeding arrangement comprises a valve unit, the valve unit being controllable to direct gas flow from the exhaust system to the intake system, and from the intake system to the exhaust system.

11. The method according to claim 1, wherein the gas feeding arrangement comprises one of an electrically controlled supercharger or an electrically controlled turbocharger.

12. The method according to claim 1, wherein the gas heating device is an intake air heater positioned in the intake system.

13. An internal combustion engine arrangement connected to an exhaust gas aftertreatment system, the internal combustion engine arrangement comprising an internal combustion engine comprising a plurality of combustion cylinders; an intake system arranged in upstream fluid communication with the internal combustion engine and configured to feed intake air into the plurality of combustion cylinders; an exhaust system arranged in downstream fluid communication with the internal combustion engine and configured to convey exhaust gas away from the internal combustion engine to the exhaust gas aftertreatment system; an exhaust gas recirculation system comprising an exhaust gas recirculation conduit connected between the intake system and the exhaust system, wherein the internal combustion engine arrangement further comprises a gas feeding arrangement and a gas heating device, each arranged in fluid communication with the exhaust gas recirculation conduit; and a control unit connected to the gas feeding arrangement and the gas heating device, characterized in that the control unit is configured to: determine a requested start of the internal combustion engine; transmit a start up signal to the gas heating device for start up of the gas heating device; and transmit a control signal to the gas feeding arrangement to direct a flow of intake air through the exhaust gas recirculation conduit from the intake system to the exhaust system, the flow of intake air being directed through the gas heating device before the intake air enters the exhaust gas aftertreatment system.

14. A vehicle comprising an internal combustion engine arrangement according to claim 13.

15. The vehicle according to claim 14, further comprising an alternative source of propulsion.

16. A computer program comprising program code means for performing the steps of claim 1 when the computer program code is run on a computer.

17. A computer readable medium carrying a computer program comprising program means for performing the steps of claim 1 when the program means is run on a computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments of the present invention, wherein:

[0040] FIG. 1 is a lateral side view illustrating an example embodiment of a vehicle in the form of a truck;

[0041] FIG. 2 is a schematic illustration of an internal combustion engine arrangement according to an example embodiment;

[0042] FIG. 3 is a schematic illustration of an internal combustion engine arrangement according to an example embodiment; and

[0043] FIG. 4 is a flow chart of a method for controlling an internal combustion engine arrangement according to an example embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0044] The present invention will now be made more fully detailed hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Like reference character refer to like elements throughout the description.

[0045] With particular reference to FIG. 1, there is provided a vehicle 1 in the form of a truck. The vehicle 1 comprises a prime mover 100 in the form of an internal combustion engine arrangement 100. The internal combustion engine arrangement 100 may preferably be fueled by e.g. a conventional fuel such as diesel, although other alternatives are conceivable. The internal combustion engine 100 is preferably operated in a four stroke fashion, i.e. operated by an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke.

[0046] Reference is made to FIG. 2, which schematically illustrates the internal combustion engine arrangement 100 according to an example embodiment. The internal combustion engine arrangement 100 is connected to an exhaust gas aftertreatment system 200. As can be seen, the internal combustion engine arrangement 100 comprises an internal combustion engine 102 comprising a plurality of combustion cylinders 101. The internal combustion engine arrangement 100 further comprises an intake system 106, through which intake air is fed into the combustion cylinders 101, and an exhaust system 108 arranged downstream the combustion cylinders 101 for receiving generated exhaust gas from the combustion cylinders 101. The exhaust system 108 is in turn connected to a turbocharger 109. In detail, the turbocharger 109 comprises a turbine 111 in fluid communication with the exhaust system 108 and a compressor 113 in fluid communication with the intake system 106.

[0047] Moreover, the internal combustion engine arrangement 100 comprises a gas heating device 122 which is arranged to heat intake air. The gas heating device 122 is depicted as positioned in the intake system 106 upstream an intake to the combustion cylinders 101. However, the gas heating device 122 can be arranged at other positions of the internal combustion engine arrangement 100 as is readily understood by the skilled person. The gas heating device 122 in FIG. 2 is illustrated in the form of an intake heater commonly used on vehicles fueled by diesel.

[0048] The internal combustion engine arrangement 100 further comprises an exhaust gas recirculation system (EGR system) 110. The EGR system 110 comprises an exhaust gas recirculation conduit (EGR conduit) 112 connected between the intake system 106 and the exhaust system 108. The EGR system 110 comprises a gas feeding arrangement 140. As will be described further below, the gas feeding arrangement 140 is arranged to selectively direct either intake air from the intake system to the exhaust system, or to direct exhaust gas from the exhaust system to the intake system, depending on current mode of operation of the internal combustion engine arrangement 100. In the example embodiment depicted in FIG. 2, the gas feeding arrangement 140 comprises a bidirectional gas flow pump 150, which is preferably arranged as a bidirectional EGR pump 150. The bidirectional gas flow pump 150 can be arranged to direct air/gas in both directions between the intake system and the exhaust system. As also illustrated, the EGR system 110 comprises a by-pass conduit 152 for being able to by-pass the bidirectional gas flow pump 150. Although not depicted, the by-pass conduit 152 preferably comprises a by-pass valve.

[0049] The gas feeding arrangement 140 may comprise other arrangements instead the bidirectional gas flow pump 150, as will be described in further detail below with reference to FIG. 3.

[0050] During operation of the internal combustion engine 102 the EGR system 110 may be operated by a control unit 180. The control unit 180 is thus preferably arranged to transmit control signals to the gas feeding arrangement 140 for operation thereof, as well as providing power to the gas feeding arrangement 140. The control unit 180 is also preferably connected to the gas heating device 122 for controlling operation thereof, and for providing power thereto.

[0051] As is further depicted in FIG. 2, the EGR system 110 comprises an EGR valve 132 and an EGR cooler 160. In FIG. 2, both the EGR valve 132 as well as the EGR cooler 160 is arranged in fluid communication between the gas feeding arrangement 140 and the exhaust system 108. The EGR valve 132 is preferably also connected to the control unit 180.

[0052] Reference is now made to FIG. 2 in combination with FIG. 4 for description of how to operate the internal combustion engine arrangement 100 before start up of the cylinders 101 of the internal combustion engine 102.

[0053] Firstly, a requested start of the internal combustion engine 102 is determined S1. Accordingly, at this point, the internal combustion engine 102 is turned off, i.e. in a non-operating state, and it is determined that the internal combustion engine 102 is about to be operated. This can be determined by means of a pre-programmed start up of the internal combustion engine arrangement, for example that a driver of the vehicle 1 has pre-programmed that he/she will start operation at a specific time in the morning. The requested start may also be determined by e.g. operating the vehicle by an electric motor with the engine turned off, wherein start of the internal combustion engine is expected due to e.g. low battery capacity of a battery operating the electric motor, or that a steep hill is expected at which operation of the internal combustion engine is needed.

[0054] When it has been determined that internal combustion engine is about to be started, the control unit 180 controls S2 the gas heating device 122 to be started up. Hereby, the gas heating device 122 initiates heating of gas fed there through, i.e. heats up intake gas conveyed there through. At the same time, or at least approximately the same time, the control unit 180 also controls S3 the gas feeding arrangement 140 to direct a flow of intake air, which has been heated by the gas heating device 122, from the intake system 106 to the exhaust system 108 via the EGR conduit 112.

[0055] Accordingly, before the internal combustion engine 102 has been turned on, warm air has been conveyed to the exhaust system 108. In particular, the heated intake air has been conveyed through the exhaust gas aftertreatment system 200. The exhaust gas aftertreatment system 200 will thus be heated and in turn more rapidly become operational.

[0056] Furthermore, the power level of the gas feeding arrangement can be controlled based on feedback of the temperature level downstream the gas heating device 122, or based on feedback of e.g. ambient temperature, EATS temperature, etc. In detail, the flow velocity through the gas feeding arrangement can be controlled based on a feedback of the temperature level. Hereby, if there is a desire to provide a high gas temperature, due to e.g. low temperature downstream the gas heating device 122 and/or low ambient temperature/EATS temperature, the power level, that is, the flow rate, of the gas feeding arrangement can be reduced to supply a relatively high temperature gas flow downstream the gas feeding arrangement.

[0057] The method described above in relation to FIGS. 2 and 4 should preferably be executed if the temperature level of the internal combustion engine arrangement 100, or the temperature of the exhaust gas aftertreatment system 200, is below a predetermined temperature threshold limit. Hence, the method is most advantageous if the internal combustion engine arrangement 100 is relatively cold.

[0058] Reference is now made to FIG. 3 illustrating the internal combustion engine arrangement 100 according to another example embodiment. The example embodiment depicted in FIG. 3 can be operated in the same way as described above for the embodiment depicted in FIG. 2. Thus, the method described in relation to FIG. 4 is equally applicable for the internal combustion engine arrangement 100 in FIG. 3. Features of FIG. 3 which are similar to the embodiment in FIG. 2 will not be described unless so explicitly indicated.

[0059] In the embodiment of FIG. 3 the EGR system 110 operates in a quite different manner as compared to the EGR system 110 of FIG. 2. Instead of having a bidirectional flow pump 150, the gas feeding arrangement 140 of FIG. 3 comprises a gas flow pump 250 which is only capable of operating in a single direction corresponding to the pumping direction of normal EGR mode, i.e. from the exhaust system 108 to the intake system 106. In other words, the gas feeding arrangement 140 can only draw exhaust gas towards the intake system 106. In order to provide for the reversed gas flow, i.e. drawing air from the intake system 106 to the exhaust system 108, valves 170a-d are provided.

[0060] The valves 170a-d, being connected to the control unit 180, are configured be actuated to re-direct the flow from the gas feeding arrangement 140 from its normal feed direction to a reversed flow direction.

[0061] As stated above, the gas flow pump 250 of FIG. 3 is running in the same first direction also for reversing the flow prior to starting of the internal combustion engine 102. Control of the valves 170a-d is instead required to change the gas flow direction through the EGR conduit 112.

[0062] A first valve 170a arranged on a first side of the pump 250 facing the intake system 106 and a second valve 170b is arranged on a second side of the pump 250 facing the exhaust system 108. The first and second valves 170a-b are therefore arranged on opposite sides of the pump 250. A first bypass line 172a is connected to the EGR conduit 112 and arranged to bypass the second valve 170b, and a third valve 170c is arranged in the first bypass line 172a. A second bypass line 172b is connected to the EGR conduit 112 and arranged to bypass the first valve 170a, and a fourth valve 170d is arranged in that second bypass line 172b.

[0063] During normal EGR mode, i.e. when directing exhaust gas from the exhaust system 108 to the intake system 106, the first and second valves 170a-b are open, while the third and fourth valves 170c-d are closed. Exhaust gas will thereby be drawn from the exhaust system 108 through the pump 250 and into the intake system 106 via the EGR conduit 112. Before engine start up, the valves 170a-d are controlled in opposite manner, i.e. the first and second valves 170a-b are closed, while the third and fourth valves 170c-d are open. The pump 250 will in this mode draw air from the intake system 106, into the EGR conduit 112, and further through the turbine 111 and into the exhaust gas aftertreatment system 200.

[0064] It should be noted that the third valve 170c could be replaced by a non-return valve, which thereby would reduce the required control of the system. Further, it should be noted that bypass lines 172a-b could also be used to bypass the pump 250, as explained earlier with respect to the bypass conduit 152. Other valve configurations are also possible within the context of this application, as long as they allow for a change in flow direction through the EGR conduit 112 while the gas flow pump 250 is running in only one direction.

[0065] It is to be understood that the present disclosure 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.