Method and system for catalyst heating

Abstract

The present invention relates to a method and system for catalyst heating. A method and system for a motor vehicle engine is provided, wherein an air supply system includes an electrically heated exhaust aftertreatment device arranged in the exhaust system, and an electric turbocharger includes an exhaust turbine and an intake compressor. In one example, the exhaust aftertreatment device can be heated and the electric turbocharger can be operated simultaneously to accelerate the light-off of the aftertreatment device while maintaining emission quality.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of German Patent Application No. 102018201278.4 filed on January 29, 2018. The entire contents of the above application are incorporated herein by reference for all purposes. Technical Field

[0003] The present disclosure generally relates to methods and systems for operating an electric turbocharger and an electrically heated exhaust catalyst for NOx reduction. Background Art

[0004] The present disclosure relates to a motor vehicle having an internal combustion engine, an exhaust system, a turbine of a turbocharger arranged in the exhaust system, and an exhaust aftertreatment device arranged in the exhaust system downstream of the turbine. Furthermore, the present disclosure relates to an operating method for operating a motor vehicle.

[0005] Vehicles may be equipped with various exhaust aftertreatment devices to reduce the release of exhaust emissions into the atmosphere. For example, a three-way catalyst can reduce the levels of various emissions, including carbon monoxide and unburned hydrocarbons, while a selective catalytic reduction (SCR) system can be used to reduce NOx levels. Exhaust catalysts are effective in treating exhaust above the catalyst light-off temperature.

[0006] DE 4139291A1 shows a method for operating an internal combustion engine with exhaust gas turbocharging, in which case the exhaust gas turbine is at least sometimes subjected to an additional fuel and / or combustion air supply with an increased exhaust gas mass flow in order to achieve detoxification of the exhaust gas and a rapid start of the exhaust gas turbine, the exhaust gas being catalytically ignited upstream of the turbine. The device for carrying out the method comprises an electrically heated catalytic converter, which is arranged in parallel with a first exhaust line upstream of the exhaust gas turbine and is sometimes subjected to the exhaust gas flow by means of a shutoff valve.

[0007] CN 104500198A discloses an electronically controlled exhaust system for a supercharged engine. The system includes a compressor, a catalytic converter, an exhaust manifold and an exhaust bypass valve. The bypass valve is controlled using an electronically controlled actuator. The electronically controlled actuator is connected to an electric control unit. A first branch pipe is connected to a fourth branch pipe. A second branch pipe is connected to a third branch pipe. Two independent exhaust port paths are formed at the outlet end of the exhaust manifold. The outlet end of the exhaust manifold is connected to the exhaust inlet of the compressor. The catalytic converter is connected to the exhaust outlet of the compressor in a closed coupling manner. This configuration is used to achieve rapid exhaust gas discharge and a shortened exhaust path.

[0008] However, the inventors have recognized potential problems with such systems. Operation of an exhaust turbine, such as an electric turbine, increases the exhaust air-fuel ratio (AFR), resulting in a reduction in exhaust NOx levels. However, during conditions when the temperature of the exhaust catalyst is below the light-off temperature, the increase in exhaust AFR caused by the electric turbine operation may further reduce the exhaust temperature, thereby extending the exhaust catalyst warm-up time. During the catalyst warm-up time (catalyst temperature below the light-off temperature), emission quality may be adversely affected due to the low NOx conversion efficiency of the catalyst. Summary of the invention

[0009] The present disclosure is based on the object of providing a motor vehicle and an operating method by means of which an improved exhaust gas aftertreatment can be achieved.

[0010] In one example, the above problems can be at least partially solved by a system for a motor vehicle, the system comprising: an internal combustion engine, an air supply system, an exhaust system, an exhaust aftertreatment device arranged in the exhaust system, a turbocharger including a turbine arranged in the exhaust system upstream of the exhaust aftertreatment device and a compressor arranged in the air supply system, an electric motor designed to drive the turbine or the compressor, and a heater designed to supply heat to the exhaust aftertreatment device; and a controller storing instructions in a non-transitory memory, the instructions being executable to supply energy to the electric motor to operate the turbocharger, and to supply energy to the heater to heat the exhaust aftertreatment device, the energy supplied to the heater being based on the energy supplied to the electric motor. In this way, by simultaneously providing power to the electric turbocharger and the catalyst heater, catalyst heating can be accelerated, emission quality can be maintained, and a desired boost pressure can be provided.

[0011] A motor vehicle according to the present disclosure comprises: an internal combustion engine, an air supply system, an exhaust system, an exhaust aftertreatment device arranged in the exhaust system (also referred to herein as an exhaust catalyst), and a turbine of a turbocharger arranged in the exhaust system upstream of the exhaust aftertreatment device or a compressor arranged in the air supply system. The air supply system according to the present invention comprises both an electric motor designed to drive the turbine or the compressor and a heater designed to supply heat to the exhaust aftertreatment device.

[0012] In this way, a motor vehicle is provided which, by means of an electric machine, can generate an electric boost (E-boost) and also heat an exhaust gas aftertreatment device. Thus, cooling of the exhaust gas aftertreatment device can be counteracted by using the electric machine. As a result, the exhaust gas aftertreatment device achieves faster light-off and improved performance.

[0013] In an advantageous configuration of the motor vehicle according to the invention, a further exhaust-gas aftertreatment device is arranged in the exhaust system downstream of the exhaust-gas aftertreatment device.

[0014] Thus, the exhaust gas aftertreatment device is arranged upstream of the other exhaust gas aftertreatment device and is the first of both to be subjected to the exhaust gas flow. The exhaust gas heated in the exhaust gas aftertreatment device by the heater can also heat the other exhaust gas aftertreatment device. In addition, an improved pre-cleaning can be performed in the exhaust gas aftertreatment device.

[0015] In a further advantageous configuration of the motor vehicle according to the invention, the heater is electrically operated.

[0016] Thus, the heater can be activated quickly. In addition, electrical energy generated by the motor vehicle by recuperation, in particular braking recuperation, can thus be used. To this end, in a further configuration, the motor vehicle is designed to perform recuperation, in particular braking recuperation.

[0017] In a further advantageous configuration of the motor vehicle according to the invention, it comprises an exhaust gas recirculation system which is formed to conduct exhaust gas from the exhaust system to the air supply system. Thus, exhaust gas recirculation can be additionally performed.

[0018] An operating method according to the present disclosure for a motor vehicle comprises operating a heater in a heating mode and operating a turbocharger in an electric boost mode in a first exercise for an exhaust aftertreatment device, the motor vehicle having an internal combustion engine, an air supply system, an exhaust system, an exhaust aftertreatment device arranged in the exhaust system, a turbine of a turbocharger arranged in the exhaust system upstream of the exhaust aftertreatment device or a compressor arranged in the air supply system, a heater for heating the exhaust aftertreatment device, and an electric motor being operated to drive the turbine or the compressor.

[0019] By means of the heating mode, the exhaust aftertreatment device is heated so that the exhaust aftertreatment device can enter a temperature window (above the light-off temperature) that is optimal for exhaust aftertreatment. Additionally, cooling of the exhaust aftertreatment device caused by electric boost operation is also offset by the heating mode. The power delivered to the heater to heat the exhaust aftertreatment device can be adjusted based on the operation of the turbocharger. As an example, if the turbocharger is operated at a higher speed to provide a desired boost and / or reduce NOx production, the exhaust air-fuel ratio can be increased (leaner than stoichiometry), and the power supplied to the heater can be increased to compensate for the cooling effect of the increased exhaust flow.

[0020] In an advantageous configuration of the operating method according to the invention, the first exercise is carried out in particular when in the electric boost check it is determined that the charge pressure undershoots a defined value and in the temperature check it is determined that the exhaust gas aftertreatment device undershoots a defined temperature. The defined value may be based on the engine torque demand and the defined temperature may be based on the light-off temperature of the exhaust gas aftertreatment device.

[0021] In an advantageous configuration of the operating method according to the invention, in the second maneuver no heating operation is performed but an electric boosting operation is performed. Thus, unnecessary heating of the exhaust gas aftertreatment device is avoided and the motor vehicle is operated more efficiently.

[0022] In an advantageous configuration of the operating method according to the invention, the second action is carried out in particular when the electric boost check determines that the charge pressure undershoots below a defined value and the temperature check determines that the exhaust gas aftertreatment device does not undershoot below a defined temperature.

[0023] In an advantageous configuration of the operating method according to the invention, no heating operation is performed and no electric boost operation is performed in the third maneuver.

[0024] Thus, unnecessary heating of the exhaust gas aftertreatment device and unnecessary increases in charge pressure are avoided and the motor vehicle operates more efficiently.

[0025] In an advantageous configuration of the operating method according to the invention, the third maneuver is carried out in particular when it is determined in the electric boost check that the charge pressure does not undershoot below a defined value.

[0026] In a further advantageous configuration of the operating method according to the invention, exhaust gas recirculation is additionally performed in the first, second or third operation. Cooling of the exhaust gas aftertreatment device caused by exhaust gas recirculation can also be additionally counteracted.

[0027] In this way, by operating the electric turbocharger and the electric heater coupled to the exhaust aftertreatment device simultaneously, NOx generation can be reduced while light-off of the exhaust aftertreatment device can be achieved more quickly. The technical effect of adjusting the power delivered to the catalyst heater based on the power delivered to the electric motor of the turbine or compressor coupled to the turbocharger is that the cooling effect caused by the dilution of the exhaust gas can be offset without overheating the catalyst, and battery power can be saved. Overall, the coordinated operation of the electric turbocharger and the catalyst heater can improve engine operation and emission quality.

[0028] It should be understood that the above summary is provided to introduce some concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is solely defined by the appended claims. Furthermore, the claimed subject matter is not limited to implementations that address any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A motor vehicle having an engine including an electrically heated catalyst (EHC) and an electric turbocharger is shown in a first exemplary configuration.

[0030] Figure 2 The motor vehicle is shown in a second exemplary configuration.

[0031] Figure 3 A flow chart illustrating an example operating method that may be implemented for operating an EHC and an electric turbocharger is shown.

[0032] Figure 4 is a graph showing the relationship between the power delivered to the electric motor and the power delivered to the EHC heater.

[0033] Figure 5 Example operations of an electric turbocharger and an EHC heater are shown. DETAILED DESCRIPTION

[0034] The following description relates to systems and methods for operating an electric turbocharger and an electrically heated catalyst for accelerating catalyst heating. As described with reference to an exemplary engine system coupled to a motor vehicle system, Figure 1 and Figure 2 As shown, the operation of the heater for the catalyst may be adjusted based on the operation of the electric turbocharger. The engine controller may be configured to execute a control routine such as Figure 3 An example routine is provided to regulate electric turbocharger operation and catalyst heater operation for reducing NOx emissions. Figure 4 is a graph showing the relationship between the power delivered from the accumulator to each of the electric turbocharger and the catalyst heater. Figure 5 Example operations of each of the electric turbocharger and the catalyst heater are shown in FIG.

[0035] exist Figure 1 and Figure 2In the drawings, a motor vehicle 10 according to the present disclosure is schematically shown in each case in an exemplary configuration. The motor vehicle 10 comprises an internal combustion engine 11, which is operated with fuel and supply air 22. In one example, the internal combustion engine can be a diesel engine and the supplied fuel can be diesel. In order to supply the supply air 22, the motor vehicle 10 comprises an air supply system 12. During operation of the internal combustion engine 11, exhaust gas 23 is generated. In order to discharge the exhaust gas 23, the motor vehicle comprises an exhaust system 13.

[0036] In the exhaust system 13, a turbine 16 of an electric turbocharger 14 (also referred to herein as an e-booster) is arranged. The turbocharger 14 generally comprises, among other things, a turbo compressor 15 arranged in the air supply system 12 of the motor vehicle 10, which is connected to the turbine 16 in a torque-transmitting manner via a shaft 17.

[0037] The motor vehicle 10 includes an electric machine 18 which, in a first configuration, is designed to drive the turbine 16. The first configuration Figure 1 In the second configuration, the motor vehicle 10 comprises an electric compressor 29 arranged in the air supply system 12, and the electric motor 18 is designed to drive the electric compressor 29. Figure 2 Here, the electric machine 18 is used in each case as an electric motor. In a second configuration, in particular, the air supply system 12 can include a bypass (not shown) around the electric compressor 29 .

[0038] Furthermore, the motor vehicle 10 comprises a first exhaust aftertreatment device 19 (also referred to herein as a catalyst) arranged in the exhaust system 13 downstream of the turbine 16. In particular, the first exhaust aftertreatment device 19 is a pre-catalytic converter. For example, the first exhaust aftertreatment device 19 is also a particulate filter. The first exhaust aftertreatment device 19 comprises a heater 20, which is designed to supply heat to the first exhaust aftertreatment device 19. Here, the heater 20 is designed to heat the first exhaust aftertreatment device 19 to a starting temperature (such as a light-off temperature), from which the first exhaust aftertreatment device 19 operates optimally. In particular, the heater 20 is an electric heater. Downstream of the first exhaust aftertreatment device 19, a second exhaust aftertreatment device 24 is arranged in the exhaust system 13. The second exhaust aftertreatment device 24 may be a main catalytic converter. The heat supplied to the first exhaust aftertreatment device 19 may be transferred to the second exhaust aftertreatment device 24 via the exhaust gas flow.

[0039] In particular, the motor vehicle 10 comprises at least one exhaust gas recirculation system 27, 28, which is designed to perform exhaust gas recirculation. At least one exhaust gas recirculation system 27, 28 is designed to guide exhaust gas 23 from the exhaust system 13 into the supply air system 12. Therefore, in particular, the motor vehicle 10 comprises a high-pressure exhaust gas recirculation system 27 and / or a low-pressure exhaust gas recirculation system 28. The high-pressure exhaust gas recirculation system (HP-EGR) 27, which comprises a first HP-EGR valve 37, branches off from the exhaust system 13 upstream of the turbine 16 and opens into the supply air system 12. There, the high-pressure exhaust gas recirculation system 27 opens downstream of the turbo compressor 15. The low-pressure exhaust gas recirculation system (LP-EGR) 28, which comprises a first LP-EGR valve 38, branches off from the exhaust system 13, in particular downstream of each of the first exhaust gas aftertreatment device 19 and the second exhaust gas aftertreatment device 24, and opens into the supply air system 12. There, the low-pressure exhaust gas recirculation system 28 opens upstream of each of the turbo compressor 15 and the electric compressor 29.

[0040] In order to detect the temperature of the first exhaust-gas aftertreatment device 19 , the motor vehicle 10 comprises in particular at least one temperature sensor 25 . Figure 1 In the embodiment of the present invention, two temperature sensors are arranged by way of example, one sensor 25 upstream of the exhaust gas aftertreatment device 19 and one sensor 25 downstream of the exhaust gas aftertreatment device 19 .

[0041] In order to supply electric energy to the electric machine 18, the motor vehicle 10 comprises in particular an accumulator 26. The accumulator 26 is part of the electrical system or is part of the electrical system of the motor vehicle 10. In particular, the motor vehicle 10 is designed to supply the accumulator 26 with electric energy generated by recuperation. In particular, the motor vehicle 10 is designed to perform braking recuperation (regenerative braking), in which when the brake pedal is depressed, kinetic energy from the vehicle is converted into electric energy and stored in the accumulator 26, and the vehicle speed is reduced (or the vehicle is stopped).

[0042] To control at least a portion of the operation of the motor vehicle 10, the motor vehicle 10 includes a control unit 21 (also referred to herein as an electronic control unit ECU) that includes a controller. The ECU 21 is shown as receiving information from a plurality of sensors 32 (various examples of which are described herein) and sending control signals to a plurality of actuators 34 (various examples of which are described herein). The controller may receive input data from the various sensors, process the input data, and trigger various actuators in response to the processed input data based on instructions or code programmed therein corresponding to one or more routines. As an example, the controller may estimate the temperature of the first exhaust aftertreatment device 19 based on inputs from the temperature sensors 25, 26, and in response to being below a threshold catalyst temperature, the controller may send a signal to the accumulator 26 to supply current to the electric heater 20, which is then actuated to supply heat to the first exhaust aftertreatment device 19.

[0043] The electric turbocharger 14 and the electric heater 20 connected to the first exhaust aftertreatment device 19 can be operated in three applications. According to the present disclosure, the heater 20 for heating the exhaust aftertreatment device 19 is operated in the first application in the heating mode, and thus heat energy is supplied to the exhaust aftertreatment device 19. In addition, the motor 18 is operated in the electric boost mode, and thus drives the turbine 16 or the compressor. Driving the turbine 16 causes the turbo compressor 15 to be driven, and thus increases the charge pressure. Driving the compressor 29 also causes an increase in the charge pressure. Here, the heating operation can be performed before the electric boost operation, or simultaneously with the electric boost operation, or after the electric boost operation. In particular, the first application is performed under the prerequisite that the charge pressure is undershot below a defined value and the exhaust aftertreatment device 19 is undershot below a defined temperature, in particular, undershot below a starting temperature. In the electric boost check, the current value of the charge pressure is compared with the defined value for this purpose, and the current temperature of the exhaust aftertreatment device 19 is compared with the defined temperature in the temperature check.

[0044] In the second operation, no heating operation is performed, but an electric boost operation is performed. The second operation is performed under the prerequisite that the electric boost check determines that the charge pressure has dropped below a defined value and the temperature check determines that the exhaust gas aftertreatment device 19 has not dropped below a defined temperature.

[0045] In the third operation, the heating operation is not performed and the electric boost operation is not performed. The third operation is performed on the premise that it is determined in the electric boost check that the charging pressure does not undershoot below a defined value.

[0046] In addition to the heating operation and / or the electric supercharging operation, exhaust gas recirculation may also be performed, in which case the exhaust gas 23 is directed from the exhaust system 13 to the air supply system 12. In the case of the electric supercharging operation driving the turbine 16, the exhaust gas 23 may be directed through the low-pressure exhaust gas recirculation system 28. In the case of the electric supercharging operation driving the compressor 29, the exhaust gas 23 may also be directed through the low-pressure exhaust gas recirculation system 28.

[0047] In this manner, in response to being below a threshold temperature of the exhaust catalyst while operating the electric turbocharger, the catalyst may be heated via an electric heater coupled to the catalyst, the power supplied to the electric heater being adjusted based on the speed of the electric turbocharger. The power supplied may be increased as the speed of the electric turbocharger increases, the electric turbocharger being driven by an electric motor coupled to one of an exhaust turbine, an electric intake compressor, and a shaft coupling the exhaust turbine to the intake compressor. The electric turbocharger may be operated to increase the exhaust air-fuel ratio in response to being below a threshold temperature of the exhaust catalyst, the threshold temperature being based on a light-off temperature of the catalyst, and the electric heater may be operated to increase the temperature of the catalyst and then maintain the temperature of the catalyst above the light-off temperature.

[0048] Although the present disclosure has been illustrated and described in more detail through preferred exemplary embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art may derive other variations therefrom without departing from the scope of protection of the present invention.

[0049] These figures are not necessarily depicted and drawn to scale and may be shown enlarged or reduced in size to provide a better overview. For this reason, the functional details disclosed herein should not be understood as limiting, but merely as an illustrative basis, which provides guidance to those skilled in the art in the art to use the present invention in various ways.

[0050] As used herein, the expression "and / or" when used in a series of two or more elements means that each of the referenced elements can be used alone, or any combination of two or more of the referenced elements can be used. For example, if a composition comprising components A, B, and / or C is described, the composition can comprise only A; only B; only C; A and B combined; A and C combined; B and C combined; or A, B, and C combined. Figure 3 An exemplary method 300 is shown that may be implemented to adjust electric turbocharger operation and catalyst heater operation to reduce NOx emissions. The method may be performed by a controller based on instructions stored in a memory of the controller and in conjunction with sensors from the engine system (such as those described above). Figure 1-Figure 2The controller may use signals received from sensors (described in the drawings) to execute instructions for performing method 300 and the remaining methods included herein. According to the methods described below, the controller may employ engine actuators of the engine system to adjust engine operation.

[0051] At 302, current vehicle and engine operating parameters may be determined. The parameters may include vehicle speed, torque demand, engine speed, engine temperature, etc. The controller may estimate the current charge pressure based on input from a manifold air pressure sensor and a desired charge pressure based on the torque demand. Additionally, the controller may estimate the temperature of an electrically heated exhaust catalyst (such as an exhaust gas catalyst) based on temperature sensors coupled to the exhaust passages upstream and / or downstream of the EHC. Figure 1 Ambient conditions including ambient temperature and pressure may also be estimated.

[0052] At 304, the routine includes determining whether the current charge pressure is lower than the desired charge pressure. If the current charge pressure is lower than the desired charge pressure, the engine torque output may not meet the torque demand, thereby adversely affecting engine performance. If it is determined that the current charge pressure is not lower than the desired charge pressure, then at 306, the current charge pressure can be maintained without operating the electric motor coupled to the electric turbocharger. The electric motor powered by the alternator can be coupled to the exhaust turbine, the intake electric compressor, or the shaft that couples the exhaust turbine to the intake compressor. The charge pressure can be maintained by adjusting the opening of the intake throttle valve based on the torque demand.

[0053] If it is determined that the current charge pressure is lower than the desired charge pressure, then at 308, an electric motor (such as a compressor) coupled to the exhaust turbine or electric compressor may be operated. Figure 1 and Figure 2 The electric motor 18 in the electric turbocharger can be used to provide boost. Operation of the electric turbocharger can be continued until the desired charge pressure is reached and the electric motor can then be deactivated. The electric motor powered by the alternator can be charged at least partially by regenerative braking.

[0054] During operation of the electric turbocharger, excess (unburned) air may flow through the engine cylinders and exhaust passages, and the engine may operate at a leaner than stoichiometric air-fuel ratio (AFR). At higher AFR 9 above a threshold AFR, the amount of NOx produced during combustion may be reduced. During operation, based on engine dilution requirements, a portion of the exhaust may be recirculated (EGR) to the intake passages. By increasing EGR, tailpipe NOx emissions may be reduced, however, EGR may have a cooling effect on the EHC.

[0055] At 310, exhaust AFR may be estimated via an oxygen sensor coupled to the exhaust passage upstream of the EHC. Since cooler air (relative to hot exhaust) flows through the EHC along with the exhaust, an increase in AFR may result in cooling of the EHC. Thus, even while reducing NOx production at leaner than stoichiometric operation of the engine, cooler air in the exhaust passage may reduce the catalyst temperature to below the catalyst light-off temperature. Below the light-off temperature, the catalyst may not be able to effectively process NOx and other combustion byproducts in the exhaust.

[0056] At 312, the routine includes determining whether the catalyst temperature is below a threshold temperature. The threshold temperature may be based on a light-off temperature of the EHC. In one example, the EHC temperature may be below the threshold temperature during a cold start. In another example, the EHC temperature may drop below the light-off temperature due to exhaust air cooling reaching the EHC caused by operation of the electric turbocharger. In yet another example, the EHC temperature may drop below the light-off temperature due to increased EGR flow.

[0057] If it is determined that the catalyst temperature is not below the threshold temperature, then at 314, the catalyst temperature may be maintained above the threshold temperature without operating the heater. If it is determined that the catalyst temperature is below the threshold, it may be inferred that catalyst heating may be required to increase the catalyst temperature above the light-off temperature and maintain its conversion capacity. At 316, a heater coupled to the catalyst is operated to provide heat to the catalyst. The controller may send a signal to the alternator (which also powers the electric motor of the electric turbocharger) to deliver power to the electric heater for accelerated catalyst warm-up.

[0058] In one example, the electric turbocharger may be operated to lean the exhaust AFR until the catalyst reaches light-off temperature, even if additional boost pressure is not desired, such as during a cold start. By running the engine leaner than stoichiometry, NOx production may be reduced until the catalyst is able to perform the conversion.

[0059] At 318, the power supplied to the catalyst heater may be adjusted based on the electric motor operation, the EGR flow rate, and the catalyst temperature. As the speed of the electric turbocharger increases (proportional to the power delivered to the electric motor), the exhaust AFR may increase accordingly and the exhaust temperature decreases. Therefore, in order to mitigate the cooling effect of the cooler exhaust gas on the exhaust catalyst, the power supplied to the catalyst heater may be directly proportional to the speed of the electric turbocharger, and the power supplied increases as the speed of the electric motor increases. As the EGR flow rate increases, the exhaust AFR may increase accordingly and the exhaust temperature decreases. Similarly, in order to offset the effect of the cooler exhaust gas on the catalyst, the power supplied to the catalyst heater may be directly proportional to the EGR flow rate, and the power supplied increases as the EGR flow rate increases. The power supplied to the catalyst heater may be inversely proportional to the catalyst temperature, such as the power supplied may decrease as the catalyst temperature increases.

[0060] In one example, the controller may determine the power delivered from the alternator to the exhaust catalyst heater using a lookup table with the inputs being each of the electric motor (which is coupled to the turbocharger) speed, the EGR flow rate, and the catalyst temperature as inputs and the catalyst heater power as output. The power supplied to the catalyst electric heater may be adjusted over time based on each of the electric motor speed, the EGR flow rate, and the catalyst temperature, and heating may be discontinued once the catalyst temperature increases above a threshold. In this way, by continually adjusting the power supplied to the catalyst heater, the cooling effect due to increased exhaust AFR may be mitigated and overheating of the catalyst may be avoided.

[0061] In this manner, during a first condition, each of the electric turbocharger and the electric heater coupled to the exhaust catalyst may be operated by supplying power from the battery, the first power supplied to the electric heater being a function of the second power supplied to the electric turbocharger, and during a second condition, the electric turbocharger may be operated by supplying power from the battery while maintaining the electric heater inactive. The first condition may include a temperature of the catalyst being below a catalyst light-off temperature, and the second condition may include a temperature of the catalyst being above the catalyst light-off temperature.

[0062] Figure 4 is shown to be supplied to an electric motor (such as Figure 1-Figure 2 The electric motor 18 in the embodiment of the present invention is used to drive the power of the electric turbocharger (exhaust turbine or electric compressor) and the electric heater (such as the electric heater) supplied to the electrically heated catalyst. Figure 1 and Figure 2 An example graph 400 of the relationship between the heater 20 in FIG. 1 and the power for a constant torque output.

[0063] The x-axis shows the power supplied to the heater, while the y-axis shows the power supplied to the electric motor. Line 402 shows the change in power supplied to the heater corresponding to the power supplied to the electric motor at a first exhaust air-fuel ratio (AFR). Line 404 shows the change in power supplied to the heater corresponding to the power supplied to the electric motor at a second exhaust AFR, which is higher than the first AFR. From the graph, it can be seen that for a constant AFR, the power supplied to the heater increases as the power supplied to the electric motor increases. Figure 4 Represents lookup table data that may be stored in a controller and used during real-time control as described in the routines herein. In particular, the graph shows how the relationship used to control the power to the motor and electric heater is adjusted as the AFR changes (in this particular example, by changing the slope, but other adjustments may also be used, such as changing from a linear relationship to a quadratic relationship, moving an offset, etc.).

[0064] Figure 5 An example timeline 500 is shown illustrating synchronous operation of an electric turbocharger and an electric heater coupled to an exhaust catalyst. The horizontal (x-axis) represents time, and vertical markers t1-t4 represent significant times in a routine of electric turbocharger and electric heater operation.

[0065] Line 502 of the first graph shows the change in engine speed estimated via the crankshaft position sensor. Line 504 of the second graph shows the catalyst temperature estimated based on one or more exhaust temperature sensors, which are connected to the exhaust passage upstream and / or downstream of the catalyst. Dashed line 505 indicates the ignition temperature of the catalyst, below which the catalyst may not effectively reduce tailpipe emissions. Dashed line 508 of the third graph indicates the actual boost pressure, while line 506 indicates the expected boost pressure estimated based on torque demand and charge pressure. Line 510 of the fourth graph indicates the exhaust air-fuel ratio (AFR) estimated via the exhaust oxygen sensor. Dashed line 511 indicates the stoichiometric AFR. Line 512 of the fifth graph shows the amount of power delivered from the alternator to the electric motor driving the electric turbocharger. Line 514 of the sixth graph shows the amount of power delivered from the alternator to the electric heater that supplies heat to the exhaust catalyst.

[0066] Prior to time t1, no combustion occurs and the engine is not operated to propel the vehicle. The electric turbocharger and the electric heater coupled to the catalyst are maintained inactive. At time t1, the engine is started from rest and the engine speed gradually increases. The actual boost pressure is lower than the desired boost pressure, thereby prompting operation of the electric turbocharger to increase the boost pressure to the desired boost pressure. Power is supplied from the alternator to the electric motor driving the turbocharger to increase the turbocharger speed. The power supplied to the motor is proportional to the difference between the desired boost pressure and the actual boost pressure. As the turbocharger speed increases, the actual boost pressure increases, but the exhaust AFR changes from stoichiometric to leaner than stoichiometric (higher AFR).

[0067] The catalyst temperature is below the threshold temperature 505, and the increase in AFR causes cooler exhaust gas to reach the catalyst, thereby prolonging the heating of the catalyst. Therefore, at time t1, the electric heater coupled to the catalyst is activated and power is supplied to the electric heater from the alternator to actively heat the catalyst. The power supplied to the electric heater is estimated by the controller based on the exhaust gas AFR and the catalyst temperature. Between time t1 and t2, as the catalyst temperature increases, the power supplied to the electric heater is reduced to reduce the possibility of overheating.

[0068] At time t2, the catalyst temperature increases to threshold temperature 505 and the electric heater is deactivated because no further heating of the catalyst is required. Additionally, at time t2, the actual boost pressure is equal to the desired boost pressure and the electric turbocharger is no longer powered by the accumulator.

[0069] Between time t2 and t3, the engine is operated at a stoichiometric AFR, where the catalyst temperature acts upon the exhaust gas flowing therethrough. At time t3, the actual boost pressure falls short of the desired boost pressure, and the electric motor is activated to supplement the boost pressure and increase it to the desired level. Due to the operation of the electric turbocharger, the exhaust AFR increases, resulting in cooler air flowing through the exhaust turbine. The cooler air flow causes the catalyst temperature to decrease below threshold 505.

[0070] In order to maintain catalyst function, power is supplied to an electric heater coupled to the catalyst between time t3 and t4. The electric heater ensures that the catalyst temperature increases and remains at or above a threshold temperature. The power supplied to the electric heater is estimated by a controller based on the exhaust AFR and the changing catalyst temperature. Between time t3 and t4, as the catalyst temperature increases, the power supplied to the electric heater is reduced to provide catalyst heating without overshooting the temperature. Since the difference between the catalyst temperature and the threshold temperature 505 is lower between time t3 and t4 relative to the difference between time t1 and t2 (between the catalyst temperature and the threshold temperature 505), the power supplied to the catalyst heater between time t3 and t4 may be lower than the power supplied to the same heater between time t1 and t2 (during a cold start).

[0071] At time t4, in response to the actual boost pressure being equal to the desired boost pressure and the catalyst temperature increasing to the threshold temperature, power may no longer be supplied to each of the electric machine and the catalyst electric heater. After time t4, the engine may be operated at a stoichiometric AFR without electric turbocharger assistance.

[0072] In this way, by adjusting the power delivered to the heater of the exhaust catalyst based on the cooling effect of the increased exhaust AFR during operation of the electric turbocharger, the catalyst can be heated up faster without overheating. The technical effect of operating the electric turbocharger during cold start conditions is that the reduced engine AFR can reduce NOx production as boost pressure is supplied until the catalyst reaches its light-off temperature and is fully functional. Overall, the simultaneous operation of the electric turbocharger and the catalyst heater can improve engine operation and emission quality.

[0073] An example system for a motor vehicle includes: an internal combustion engine, an air supply system, an exhaust system, an exhaust aftertreatment device arranged in the exhaust system, a turbocharger including a turbine arranged in the exhaust system upstream of the exhaust aftertreatment device and a compressor arranged in the air supply system, an electric motor designed to drive the turbine or the compressor, and a heater designed to supply heat to the exhaust aftertreatment device; and a controller storing instructions in a non-transitory memory, the instructions executable to supply energy to the electric motor to operate the turbocharger, and to supply energy to the heater to heat the exhaust aftertreatment device, the energy supplied to the heater being based on the energy supplied to the electric motor. In any of the foregoing examples, additionally or optionally, the heater is electrically operated, and the energy supplied to the heater is proportional to the energy supplied to the electric motor. In any or all of the foregoing examples, additionally or optionally, the method further includes: an exhaust gas recirculation system, the exhaust gas recirculation system being designed to direct a certain amount of exhaust gas from the exhaust system to the air supply system, the energy supplied to the heater being further based on the amount of exhaust gas recirculated to the air supply system. In any or all of the foregoing examples, additionally or optionally, each of the turbocharger and the heater is operated when the charge pressure is determined to undershoot below a defined value in the electric boost check and the exhaust aftertreatment device is determined to undershoot below a defined temperature in the temperature check. In any or all of the foregoing examples, additionally or optionally, the electric machine is deactivated in response to the charge pressure being above a defined value, and wherein the heater is deactivated in response to exhaust aftertreatment device light-off. In any or all of the foregoing examples, additionally or optionally, the defined value is based on an engine torque demand, and wherein the defined temperature is based on a light-off temperature of the exhaust aftertreatment device.

[0074] Another example method for an engine includes: in response to a threshold temperature below an exhaust catalyst when an electric turbocharger is operating, heating the catalyst via an electric heater coupled to the catalyst, and adjusting the power supplied to the electric heater based on the speed of the electric turbocharger. In any of the foregoing examples, in addition or optionally, the power supplied is increased as the speed of the electric turbocharger increases, the electric turbocharger is driven by an electric motor, the electric motor is coupled to one of the exhaust turbine, the electric intake compressor, and the shaft connecting the exhaust turbine to the intake compressor. In any or all of the foregoing examples, in addition or optionally, each of the electric turbocharger and the electric heater is powered by a common alternator. In any or all of the foregoing examples, in addition or optionally, the power supplied is further adjusted based on the temperature of the exhaust catalyst, wherein the power decreases as the temperature of the catalyst increases. In any or all of the foregoing examples, in addition or optionally, the power supplied is further adjusted based on the exhaust gas recirculation (EGR) flow from the engine exhaust to the engine intake, and the power increases as the EGR flow increases. In any or all of the foregoing examples, additionally or optionally, the electric turbocharger is operated in response to the actual charge pressure being less than a target charge pressure, the target charge pressure being based on an operator torque demand. In any or all of the foregoing examples, additionally or optionally, the electric turbocharger is operated to increase the exhaust air-fuel ratio in response to a temperature below a threshold temperature of an exhaust catalyst, the threshold temperature being based on a light-off temperature of the catalyst. In any or all of the foregoing examples, additionally or optionally, the electric heater is operated to increase the temperature of the catalyst, and then maintain the temperature of the catalyst above the light-off temperature.

[0075] In another example, a method for an engine includes: during a first condition, operating an electric turbocharger and each of an electric heater coupled to an exhaust catalyst by supplying power from a battery, the first power supplied to the electric heater being a function of a second power supplied to the electric turbocharger, and during a second condition, operating the electric turbocharger by supplying power from the battery while keeping the electric heater inactive. In any or all of the foregoing examples, additionally or optionally, the first condition includes a temperature of the catalyst being below a catalyst light-off temperature, and the second condition includes a temperature of the catalyst being above a catalyst light-off temperature. In any or all of the foregoing examples, additionally or optionally, the first condition includes a cold start when the electric turbocharger is operated to reduce the exhaust air-fuel ratio below a threshold. In any or all of the foregoing examples, additionally or optionally, the engine is coupled inside a hybrid vehicle, and wherein the battery is charged by regenerative braking. In any or all of the foregoing examples, additionally or optionally, the electric turbocharger includes an electric motor coupled to an exhaust turbine or an electric compressor, the electric motor being capable of rotating the exhaust turbine or the electric compressor. In any or all of the foregoing examples, additionally or optionally, the second power increases with one or more of an increase in the first power and a decrease in the temperature of the catalyst.

[0076] Note that the example control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in combination with various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. In this way, the various actions, operations, and / or functions shown can be performed in the order shown, in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown can be repeatedly performed according to the specific strategy used. Further, the described actions, operations, and / or functions can graphically represent the code in the non-transitory memory of a computer-readable storage medium that will be programmed into the engine control system, wherein the described actions are performed in combination with an electronic controller by executing instructions in the system, and the system includes various engine hardware components.

[0077] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and these specific embodiments should not be viewed in a limiting sense, as many variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and / or properties disclosed herein.

[0078] As used herein, unless otherwise indicated, the term "about" is interpreted to mean a range of ±5%.

[0079] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. These claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included within the subject matter of the present disclosure.

Claims

1. A system for a motor vehicle, comprising: An internal combustion engine, an air supply system, an exhaust system, an exhaust aftertreatment device arranged in the exhaust system, a turbocharger comprising a turbine arranged in the exhaust system upstream of the exhaust aftertreatment device and a compressor arranged in the air supply system, an electric motor designed to drive the turbine or the compressor, and a heater designed to supply heat to the exhaust aftertreatment device; as well as A controller storing instructions in a non-transitory memory, the instructions executable to: supplying energy to the electric machine to operate the turbocharger; and supplying energy to the heater to heat the exhaust aftertreatment device, the energy supplied to the heater being based on energy supplied to the motor; wherein the heater is electrically operated and the energy supplied to the heater is proportional to the energy supplied to the motor.

2. The system according to claim 1, further comprising: An exhaust gas recirculation system is designed to direct a certain amount of exhaust gas from the exhaust system to the supply air system, the energy supplied to the heater being further based on the amount of exhaust gas recirculated to the supply air system.

3. The system of claim 1 , wherein each of the turbocharger and the heater is operated when a charge pressure is determined to have undershot below a defined value in an electric boost check and when a temperature check determines that the exhaust aftertreatment device has undershot below a defined temperature. 4 . The system of claim 3 , wherein the electric machine is deactivated in response to the charge pressure being above the defined value, and wherein the heater is deactivated in response to exhaust aftertreatment device light-off. 5 . The system of claim 3 , wherein the defined value is based on an engine torque demand, and wherein the defined temperature is based on a light-off temperature of the exhaust aftertreatment device.

6. A method for an engine, comprising: When the electric turbocharger is being operated, in response to a temperature below a threshold of the exhaust catalyst, heating the catalyst via an electric heater coupled to the catalyst, power supplied to the electric heater being adjusted based on a speed of the electric turbocharger; The power supplied to the electric heater is proportional to the power supplied to the electric turbocharger.

7. The method of claim 6, wherein the power supplied is increased as the speed of an electric turbocharger increases, the electric turbocharger being driven by an electric motor coupled to one of an exhaust turbine, an electric intake compressor, and a shaft connecting the exhaust turbine to the intake compressor. 8 . The method of claim 6 , wherein each of the electric turbocharger and the electric heater is powered by a common alternator. 9 . The method of claim 6 , wherein the power supplied is further adjusted based on a temperature of the exhaust catalyst, the power decreasing as the temperature of the catalyst increases.

10. The method of claim 6, wherein the supplied power is further adjusted based on exhaust gas recirculation (EGR) flow from the engine exhaust to the engine intake, wherein the power increases with increasing EGR flow. 11 . The method of claim 6 , wherein the electric turbocharger is operated in response to an actual charge pressure being less than a target charge pressure, the target charge pressure being based on an operator torque request. 12 . The method of claim 6 , wherein the electric turbocharger is operated to increase exhaust air-fuel ratio in response to the temperature being below the threshold temperature of the exhaust catalyst, the threshold temperature being based on a light-off temperature of the catalyst.

13. The method of claim 6, wherein the electric heater is operated to increase the temperature of the catalyst and then maintain the temperature of the catalyst above a light-off temperature.

14. A method for an engine, comprising: During the first condition, operating each of an electric turbocharger and an electric heater coupled to an exhaust catalyst by powering from a battery, a first power supplied to the electric heater being a function of a second power supplied to the electric turbocharger; and During the second condition, operating the electric turbocharger by supplying power from the battery while maintaining the electric heater inactive; The first power supplied to the electric heater is proportional to the second power supplied to the electric turbocharger.

15. The method of claim 14, wherein the first condition includes a temperature of the catalyst being below a catalyst light-off temperature, and the second condition includes the temperature of the catalyst being above the catalyst light-off temperature. 16 . The method of claim 14 , wherein the first condition comprises a cold start when the electric turbocharger is operated to reduce an exhaust air-fuel ratio below a threshold.

17. The method of claim 14, wherein the engine is coupled within a hybrid vehicle, and wherein the battery is charged by regenerative braking.

18. The method of claim 14, wherein the electric turbocharger comprises an electric motor coupled to an exhaust turbine or an electric compressor, the electric motor being capable of rotating the exhaust turbine or the electric compressor.

19. The method of claim 14, wherein the second power increases with one or more of an increase in the first power and a decrease in a temperature of the catalyst.

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