CN113646519A

CN113646519A - System and method for maintaining thermal aftertreatment while engine is idling

Info

Publication number: CN113646519A
Application number: CN202080027706.0A
Authority: CN
Inventors: 詹姆斯·E·麦卡锡; 米哈伊·多罗班图
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2019-03-25
Filing date: 2020-03-25
Publication date: 2021-11-12
Also published as: WO2020192973A1; EP3947944A1

Abstract

The present disclosure provides a transmission system selectively coupled to an engine crankshaft of an internal combustion engine disposed on a vehicle, the transmission system including a transmission, an aftertreatment system, an accessory device, and a controller. The aftertreatment system reduces emissions in the exhaust of the internal combustion engine. The accessory device is configured to provide power. The controller operates in an aftertreatment heating mode such that the aftertreatment system is heated to an elevated temperature, thereby reducing emissions based on the elevated temperature. The controller is configured to heat the aftertreatment system to achieve an enthalpy between one (1) kilowatt-hour (kWh) and two (2) kWh within two minutes of engine start-up by: (i) operating the internal combustion engine in a cylinder deactivation mode (CDA); (ii) operating the internal combustion engine at an elevated idle speed; and (iii) operating the accessory device at the threshold power.

Description

System and method for maintaining thermal aftertreatment while engine is idling

Technical Field

The present disclosure relates generally to a transmission system and related method for operating a motor-generator coupled to a countershaft of the transmission system at engine start-up to generate higher exhaust heat in exhaust aftertreatment.

Background

Federal Test Procedures (FTP) force current engine designs to tend to require reduced emissions and improved fuel economy. The addition of low duty cycles, in-service emissions compliance, and extended idle operation increases this level of severity. One of the challenges in reducing emissions is to effectively manage emissions at engine start-up. It is well known that nitrogen oxide (NOx) aftertreatment systems are temperature sensitive. High NOx conversion starts between 220C and 280C depending on the catalyst formulation. Typically at engine start-up, the idle exhaust temperature may be between 110C and 150C. In this regard, a certain amount of time is required for the exhaust to heat from the typical exhaust temperature to an elevated temperature that meets the desired 95% (or more) efficiency target. Operation of the engine during this amount of time is inefficient for NOx conversion. In some examples, the amount of time is about 600 seconds. Even with cylinder deactivation, the Selective Catalytic Reduction (SCR) temperature may be reduced to about 200C at idle. It is desirable to provide a system that quickly and efficiently raises the SCR temperature at start-up, and also maintains the temperature within the efficiency target throughout idle speed or at all times when the engine is turned on.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Disclosure of Invention

The present disclosure provides a transmission system selectively coupled to an engine crankshaft of an internal combustion engine disposed on a vehicle, the transmission system including a transmission, an aftertreatment system, an accessory device, and a controller. The transmission has an input shaft, a primary shaft, an output shaft, and a secondary shaft offset from the input shaft. The countershaft is drivably connected to the first input shaft and the main shaft. Aftertreatment systems reduce emissions in the exhaust of internal combustion engines. The accessory device is configured to provide power. The controller operates in an aftertreatment heating mode such that the aftertreatment system is heated to an elevated temperature, thereby reducing emissions based on the elevated temperature. The controller is configured to heat the aftertreatment system to achieve an enthalpy between one (1) kilowatt-hour (kWh) and two (2) kWh within two minutes of engine start-up by: (i) operating the internal combustion engine in a cylinder deactivation mode (CDA); (ii) operating the internal combustion engine at an elevated idle speed; and (iii) operating the accessory device at the threshold power.

According to an additional feature, operating the internal combustion engine at the CDA and operating the internal combustion engine at the elevated idle speed provides between 7 kilowatts and 11 kilowatts of power. The accessory device operates at between 9 kilowatts and 14 kilowatts. The controller is operable in the aftertreatment heating mode to provide between 27 kilowatts and 33 kilowatts of power by simultaneously operating the internal combustion engine at the CDA and at an elevated idle speed and operating the accessory drive at a threshold power to achieve an enthalpy between one (1) kilowatt-hour (kWh) and two (2) kWh in three minutes.

In other features, the transmission system may include at least one battery that provides voltage regulation. The at least one battery may be 48 volts. The accessory device may be an electric heater. The controller may be configured to suspend the aftertreatment heating mode when an enthalpy between one (1) kWh and two (2) kWh is reached until a Selective Catalytic Reduction (SCR) temperature falls below a threshold. The controller may reenter the aftertreatment heating mode when the SCR temperature falls below the threshold until the aftertreatment system returns to an enthalpy between one (1) kWh and two (2) kWh. The controller may be configured to heat the aftertreatment system to achieve an enthalpy of 1.3 kWh.

The present disclosure provides a transmission system selectively coupled to an engine crankshaft of an internal combustion engine disposed on a vehicle, the transmission system including a transmission, an aftertreatment system, an electric heater, and a controller. The transmission has an input shaft, a primary shaft, an output shaft, and a secondary shaft offset from the input shaft. The countershaft is drivably connected to the first input shaft and the main shaft. Aftertreatment systems may reduce emissions in the exhaust of internal combustion engines. An electric heater may be provided in the aftertreatment system. The controller is operable in an aftertreatment heating mode such that the aftertreatment system is heated to an elevated temperature to reduce emissions based on the elevated temperature, the controller operating in the aftertreatment heating mode during idle.

According to an additional feature, the controller operates the engine in a cylinder deactivation mode (CDA) during the aftertreatment heating mode such that the aftertreatment system operates at an elevated temperature. During the aftertreatment heating mode, the controller switches on the electric heater in conjunction with operating the engine in the CDA mode. The controller may operate in an aftertreatment heating mode for a first period of time to raise the aftertreatment system to a predetermined temperature. The predetermined temperature may be about 350 degrees celsius. More specifically, the predetermined temperature is about 350 degrees Celsius to ensure that cooling is prevented, thereby keeping the heating function to a minimum. After the first period of time, the controller may turn off the electric heater. After the dwell time, the controller may determine that the temperature of the aftertreatment system has decreased below the desired celsius value and turn on the electric heater.

A method of operating a transmission system selectively coupled to an engine crankshaft of an internal combustion engine having a transmission, an aftertreatment system, and an accessory device configured to provide power is provided. Control determines whether the aftertreatment system is operating below a threshold temperature. A controller operates the transmission system in a post-processing mode. The internal combustion engine is operated in a cylinder deactivation mode (CDA). The internal combustion engine operates at elevated idle speed. The accessory device operates at a threshold power. The aftertreatment heating mode is exited upon reaching an enthalpy between one (1) kilowatt-hour (kWh) and two (2) kWh within two minutes of engine start-up.

According to other features, operating the internal combustion engine at the CDA and operating the internal combustion engine at the elevated idle speed provides between 7 kilowatts and 11 kilowatts of power. The accessory device operates at between 9 kilowatts and 14 kilowatts. The controller is operable in the aftertreatment heating mode to provide between 27 kilowatts and 33 kilowatts of power to achieve an enthalpy of one (1) kilowatt-hour (kWh) and two (2) kWh in three minutes by simultaneously operating the internal combustion engine at the CDA and at the elevated idle speed and operating the accessory drive at the threshold power. The aftertreatment heating mode is exited until the Selective Catalytic Reduction (SCR) temperature drops below a threshold. Reentering the aftertreatment heating mode when the SCR temperature falls below the threshold until the aftertreatment system returns to an enthalpy between one (1) kWh and two (2) kWh. Operating the transmission system in the aftertreatment heating mode includes heating the aftertreatment system to an enthalpy of 1.3 kWh.

Drawings

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1A is a schematic illustration of a transmission system constructed in accordance with the present disclosure and configured to implement various aftertreatment heating modes.

FIG. 1B is a schematic illustration of an automatic mechanical transmission system coupled to an engine having a motor-generator coupled to a countershaft according to one example of the present disclosure;

FIG. 2 is another schematic illustration of the automatic mechanical transmission system of FIG. 1;

FIG. 3 is a graph illustrating NOx conversion efficiency versus Selective Catalytic Reduction (SCR) temperature;

FIG. 4 illustrates various power flow scenarios in accordance with configurations of the present disclosure;

FIGS. 5A and 5B illustrate background information showing NOx demand standard changes and heating targets according to various examples of the present disclosure;

FIG. 6 is a graph of an example RPM and torque, where 0.02g/hp-hr NOx is a 2024 year target;

FIG. 7A is a graph of a cold cycle according to one example of the present disclosure;

FIG. 7B is a graph of SCR efficiency for the cold cycle graph of FIG. 7A;

FIG. 7C is a thermal cycle plot according to one example of the present disclosure;

FIG. 7D is a plot of SCR efficiency for the thermal cycle plot of FIG. 7C;

FIGS. 8A and 8B show background graphs of aftertreatment heating turbine outlet and SCR temperatures during heavy-duty (HD) Federal Test Procedure (FTP);

FIG. 9 shows HD FTP with 20kW battery power, showing a first plot of power demand during the discharge cycle and a second plot of 20kW power addition;

FIG. 10 illustrates a first plot of baseline torque, a second plot of new torque, and a third plot of RPM in accordance with the present disclosure;

fig. 11 and 12 show 20kW continuous/bottom power for batteries according to various examples of the present disclosure;

FIG. 13 is a graph of engine load versus engine speed illustrating that cylinder deactivation is beneficial for rapid heating to make the exhaust hotter and drive more enthalpy to the aftertreatment system;

14A and 14B show graphs of torque for an engine operating in a normal mode and an engine operating in a cylinder deactivation mode;

FIG. 15 illustrates engine flywheel angular acceleration (i.e., noise and/or vibration) versus engine speed;

FIG. 16 illustrates a first exemplary scenario for operating the transmission system to achieve thermal aftertreatment at engine start-up;

FIG. 17 illustrates a second exemplary scenario for operating the transmission system to achieve thermal aftertreatment at engine start-up;

FIG. 18 illustrates exemplary power and speed for warming aftertreatment at engine start-up;

FIG. 19 shows temperature versus time for an SCR catalyst that decreases when operating at idle for an extended period of time even when cylinder deactivation is added;

FIG. 20 illustrates a system and method for achieving an enthalpy of about 1.3kWh in a short period of time to an elevated aftertreatment system temperature according to one example of the present disclosure;

FIG. 21 illustrates temperature versus time when operating the system of the present disclosure to warm up and maintain heat indefinitely in accordance with the present disclosure;

FIG. 22 illustrates a method of adding 19kW of heat to the aftertreatment system to raise the temperature by about 1.5 degrees Celsius per second;

FIG. 23 illustrates a Federal testing protocol for heating using another method of operating the system of the present disclosure by adding cylinder deactivation to reach 250 degrees Celsius at 249 seconds;

FIG. 24 illustrates a Federal testing procedure showing NOx at engine start-up;

FIG. 25 illustrates a method of adding 10kW of heat to reach 250 degrees Celsius at 104 seconds;

FIGS. 26A and 26B illustrate cylinder deactivation with close-coupling catalyst enabled to allow SCR desulfation;

FIG. 26C illustrates two exemplary catalyst configurations according to the present disclosure;

FIG. 27A is a graph of NOx versus time showing the effect of moving one SCR upstream to heat up faster;

FIG. 27B is a graph of cumulative NOx versus time showing the effect of moving one SCR upstream to heat up faster;

FIG. 28 is a graph of temperature versus time for a close-coupled SCR with CDA and a current SCR without CDA;

FIG. 29 is a graph of temperature versus time for a close-coupled SCR with CDA and a current SCR without CDA showing a low duty cycle with low nitrogen oxide orders of magnitude and 5% carbon dioxide savings;

FIG. 30 illustrates a table showing various methods of rapidly warming an aftertreatment system according to the present disclosure;

FIG. 31 illustrates another table showing various methods of rapidly warming an aftertreatment system according to the present disclosure;

FIG. 32 is a graph of engine speed and engine torque versus time using the principles of the present disclosure;

FIG. 33 is a graph showing temperature and heating rate versus time with the addition of 10kW and 19kW of heat, according to the present disclosure;

FIG. 34 is a graph showing temperature and heating rate versus time for cold Federal test procedure heating;

FIG. 35 is a schematic diagram illustrating a baseline warming approach;

FIG. 36 is a schematic diagram illustrating a problem to be solved by the present patent application;

FIG. 37 is a schematic diagram illustrating operating the engine under CDA and at elevated idle speed;

FIG. 38 is a schematic illustration of a transmission system configured to operate an engine at CDA and at an elevated idle speed while increasing engine load and operating an electric heater according to the present disclosure; and is

FIG. 39 is a schematic diagram of the transmission system of FIG. 38 illustrating various times at which heat is obtained for aftertreatment in accordance with the present teachings.

Detailed Description

The following disclosure relates to optimizing post-processing efficiency. As noted above, Federal Testing Procedures (FTP) force current engine designs to tend to require reduced emissions and improved fuel economy. The addition of low duty cycles, in-service emissions compliance, and extended idle operation increases this level of severity. It is well known that nitrogen oxide (NOx) aftertreatment systems are temperature sensitive. High NOx conversion starts between 220C and 280C depending on the catalyst formulation. In particular, as shown in fig. 3, NOx conversion may have an efficiency of 95% or more when the Selective Catalytic Reduction (SCR) catalyst temperature is between 300C and 450C. Typically at start-up, the idle exhaust temperature may be between 110C and 150C. In this regard, a certain amount of time is required for the exhaust to heat from the typical exhaust temperature to an elevated temperature that meets the desired 95% (or more) efficiency target. Operation of the engine during this amount of time is inefficient for NOx conversion. In some examples, the amount of time is about 600 seconds. The present disclosure provides a configuration and control strategy that rapidly increases exhaust temperature to minimize this amount of inefficient operation time and to achieve the desired 95% efficiency range.

As will be appreciated from the following discussion, the present disclosure replaces the vehicle electrical system starting with a conventional "front end accessory drive" (FEAD) that drives accessory components such as the charging system (alternator) and the compressor that drives the HVAC air conditioner. Instead, the vehicle electrical system according to the present disclosure is driven by the transmission layshaft. Such a configuration allows a new operating mode of coasting at engine shutdown (engine shutdown coasting or EOC) while still providing power by driving the charging system from the wheels while the engine is stopped (fuel is drained) and the vehicle is still moving.

Referring initially to fig. 1A and 1B, an AMT system, generally designated 10, is constructed and indicated in accordance with one example of the present disclosure. The AMT system 10 is selectively coupled to a fuel-controlled engine 12 (such as a diesel engine, etc.), a multi-speed transmission 14, and a primary clutch 16 drivingly interposed between the engine 12 and an input shaft 18 of the transmission 14. The transmission 14 may be a compound transmission including a main transmission section connected in series with a splitter and/or combiner auxiliary section. Transmissions of this type, especially those used in heavy vehicles, typically have 9, 10, 12, 13, 16 or 18 forward speeds. A transmission output shaft 20 extends outwardly from the transmission 14 and is drivingly connected to a vehicle driven axle 22, typically through a driveshaft 24.

The master clutch 16 includes a driving portion 16A connected to the engine crankshaft/flywheel 26 and a driven portion 16B coupled to the transmission input shaft 18 and adapted to frictionally engage the driving portion 16A. An Electronic Control Unit (ECU)28 is provided for receiving input signals 30 and processing the input signals in accordance with predetermined logic rules to issue command output signals 32 to the transmission system 10. The system 10 may also include a rotational speed sensor 34 for sensing a rotational speed of the engine 12 and providing an output signal (ES) indicative thereof, a rotational speed sensor 36 for sensing a rotational speed of the input shaft 16 and providing an output signal (IS) indicative thereof, and a rotational speed sensor 38 for sensing a speed of the output shaft 20 and providing an Output Signal (OS) indicative thereof. The main clutch 16 may be controlled by a clutch actuator 50 in response to an output signal from the ECU 28.

The transmission 14 has one or more main shaft segments 40. The main shaft 40 is coaxial with the input shaft 18. The transmission 14 has a first countershaft 42 and a second countershaft 44. Countershafts 42 and 44 are offset from input shaft 18 and main shaft 40. The

countershafts

42 and 44 are shown as being offset from one another, however in some examples, the

countershafts

42 and 44 may be coaxial with one another. The output shaft 20 may be coaxial with the main shaft 40.

The first countershaft 42 is supported by bearings for rotation within the transmission 14 housing. The first countershaft 42 of the transmission 14 has countershaft gears 50, 52, 54, 56 and 58. The second countershaft 44 is supported by bearings for rotation within the transmission 14 housing. Second countershaft 44 of transmission 14 has countershaft gears 60, 62, 64, 66 and 68. The main shaft 14 of the transmission 40 has main shaft gears 70, 72, 74, 76, and 78. Main clutch 16 may selectively transfer torque to transmission 14. The headset clutch 84, the first sliding dog clutch 88 and the second sliding dog clutch 90 may move side to side as shown in FIG. 2 to connect the various main shaft gears 70-78 and countershaft gears 50-58 and 60-68 to achieve the desired drive gear and torque path within the transmission 14.

The right hand end of the main shaft 40 is drivably connected to the sun gear 110. The planet carrier 112 is connected to or integral with an output shaft 20 which is drivably connected to vehicle traction wheels by a drive axle 22. The ring gear 118 engages planet pinions 120 carried by the carrier 112.

According to one example of the present disclosure, motor generator 140 may be selectively coupled to second countershaft 44 (or transmission power take off PTO). As will be understood herein, the motor generator 140 is configured to operate in two opposite modes. In the first mode, motor generator 140 operates as a motor by consuming electrical power to generate mechanical power. In the second mode, motor generator 140 operates as a generator by consuming mechanical power to generate electric power. In one configuration, the planetary gear assembly 144 may be coupled between the second countershaft 44 and the motor generator 140. The planetary gear assembly 144 may be a step-up gear assembly having a sun gear 150. Planetary carrier 152 is connected to or integral with second countershaft 44, which is drivably connected to motor generator 140. The ring gear 156 engages planet pinions 160 carried by the carrier 152.

By way of example only, motor-generator 140 may be a 6 kilowatt-20 kilowatt, 24 volt-48 volt electric motor. Motor generator 140 may ultimately be driven by second countershaft 44 and electrically connected to integrated motor drive and converter 170. The integrated motor drive and converter 170 may provide buck conversion and battery management. In the non-limiting example provided, the integrated motor drive and converter 170 may be a 24-48 volt three-phase inverter. The first battery 180 may be electrically connected to the integrated motor drive and converter 170. The second battery 182 may be electrically connected to the integrated motor drive and converter 170. The first battery 180 may be a 24-48 volt battery that powers various battery powered components 184 of the vehicle, such as hybrid cooling, Heating Ventilation and Air Conditioning (HVAC), air compressors, power steering, and other components. While the above description provides for implementations of 24 volts and 48 volts, in other examples, the motor-generator and related components may be configured for 12 volt operation. Further, in other examples, the transmission system 10 may incorporate an alternator only in the generating mode without the need for an integrated motor drive and converter 170. In the figures, the feature 140 will be an alternator. It should be appreciated that the transmission system 10 may use only an alternator, such that inertia braking and synchronization may be performed with the second countershaft 44 decelerating and not accelerating. In other examples, as will be understood herein, the electric heater (fig. 20) implementation does not require voltage regulation. A battery is not necessary. In this regard, the voltage may vary during operation of the electric heater.

With specific reference to fig. 1A-2, additional features of the present disclosure will be described in more detail. The engine 12 includes an exhaust manifold 210 that directs exhaust gases to an aftertreatment assembly 214 that includes a turbocharger system 220 having a turbine 222 and a compressor 224. It is well known that diesel exhaust can contain emissions including carbon monoxide (CO), unburned Hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter such as soot. The aftertreatment component 214 may also include a Diesel Oxidation Catalyst (DOC)230, a Diesel Particulate Filter (DPF)232, and a selective catalytic reduction catalyst (SCR) 234.

DOC 230 may be placed in the exhaust stream of a diesel engine and typically contains platinum group metals and/or alkali metals. These catalysts promote the conversion of OC and HC emissions to carbon dioxide and water. SCR 234 is used to convert NOx and N₂And may include an alkali metal and utilize an ammonia reducing agent, such as an aqueous urea solution. The aqueous urea solution may be injected into the exhaust stream downstream of DOC 230. The ammonia formed reacts with NOx in the exhaust stream over SCR 234 to form N₂. DPF 232 collects soot from the engine exhaust. The accumulated particulates are burned at an elevated temperature to regenerate the filter.

As shown in FIG. 3, the optimum point for NOx conversion is typically between 300C and 450C. In this regard, it is desirable to rapidly heat the aftertreatment component 214 upon startup. The teachings of the present disclosure provide a system and method for operating the engine 12 in a rapid heating mode. As used herein, the term "start-up" is used to refer to a period of time (300C to 450C) to reach a desired optimum point for NOx conversion. In other words, "start" is used to define the period of time from engine cranking until the desired hot catalyst temperature is reached.

Referring to fig. 4, two post-processing (rapid) heating modes according to the present disclosure are shown. The aftertreatment heating mode provides additional load on the engine 12 to heat the aftertreatment system 214 at cold start and until the aftertreatment system 214 is heated. The same power may be delivered to the wheels 22, while additional load may be directed to the

batteries

180, 182. In this regard, the motor generator 140 may implement a load on the transmission 14, which may warm the engine 12 operation. As will be understood herein, the present disclosure provides a number of configurations and methods that may be used alone or in combination to load the engine 12 to warm its operation and thus raise the temperature of the aftertreatment system 214 to a desired range.

In some examples, if the aftertreatment system 214 has warmed up, the additional load at startup may not need to be considered. The controller 250 may manage engine power, transmission power routing, and battery charge status. A thermocouple provided in the aftertreatment system 214 may provide a signal indicative of the temperature of the aftertreatment system 214 to the controller 250. It should be understood that energy may be used in accordance with the present disclosure by routing power (in this example +20kW) to the

batteries

180, 182. It should be understood that other kW may be routed, such as 5kW, 10kW, 15kW, 25kW, 50kW, or other kW suitable for producing a load on the engine 12. The more power consumed, the faster the engine 12 will heat up. The controller 250 may require 20kW of power continuously or maintain a minimum or "bottom" at 20kW of power. When the power is above 20kW, the controller 250 may direct all power to the wheel 22 and stop charging the

batteries

180, 182. In this regard, the transmission 14 may direct power to the wheels 22 or

batteries

180, 182. The engine 12 can still be started in both configurations when the transmission 14 is directing power to the correct position. In one configuration, power may be sent to the wheel 22 and

batteries

180, 182 simultaneously. In another configuration, the transmission 14 may disconnect power to the wheel 22 at launch.

Additionally or alternatively, other means of routing power may be used within the scope of the present disclosure. For example, power may be used (consuming energy) by turning on an engine fan, charging a gas tank, using any vehicle accessories, turning on lights, turning on a fan, operating the transmission 14 inefficiently (such as at an un-optimized gear ratio and/or preventing deceleration), and so forth. When controller 250 routes additional power, engine 12 and aftertreatment system 214 will therefore heat up quickly to achieve more efficient NOx conversion more quickly (see FIG. 3).

By way of example only, as shown in fig. 5, the present disclosure relates to heating an engine to a temperature that achieves a desired aftertreatment efficiency. The first graph shows the NOx (at engine output) calibration for 1.5g/kWh operation. The second graph shows the NOx (at engine output) calibration for 5g/kWh of operation. More fuel will be saved when operating higher engine out NOx calibration. However, the aftertreatment system will exceed the desired limit at the tailpipe more quickly. In this regard, when operating a 5g/kWh NOx (at engine output) calibration, 100% NOx conversion needs to be achieved 50 seconds into the cycle. Similarly, when operating 1.5g/kWh of NOx (at engine output), 100% NOx conversion is required to be achieved at 400 seconds into the cycle (from engine start). For emissions requirements of 2024, the engine will need to be heated for 400 seconds (and more preferably 50 seconds) to meet Federal Test Procedure (FTP) requirements. The teachings of the present disclosure provide a solution for rapidly heating the aftertreatment system 214 to meet this new requirement.

From this perspective, in a diesel configuration, the conventional heating mode may take up to ten minutes to reach the desired temperature of the aftertreatment system 214. The present disclosure provides a solution for heating the aftertreatment system 214 significantly faster. The teachings of the present disclosure are also applicable to hybrid electric vehicles. In some examples, the teachings are particularly useful in hybrid-electric configurations because the internal combustion engine is less used and has less opportunity to heat up quickly. In this regard, the size of the motor generator 140 will be larger than that shown in fig. 1A to 2. In other arrangements, the motor generator 140 may be directly coupled to the engine 12 without the transmission 14 disposed therebetween. At this time, the motor generator 140 may be disposed at any position on the drive line where a load from the engine 12 is required, thereby allowing the engine to reach a higher temperature faster.

FIG. 6 illustrates an exemplary emissions cycle test in a system of the teachings of the present disclosure that does not implement rapid heating. FIG. 6 shows time on the x-axis, RPM on the left y-axis and torque in NM on the right y-axis. Regions within 600 seconds are identified as too cold. Rapid heating in this region is desirable. FIG. 7A shows the outlet temperature of the turbine 222 during the cycle shown in FIG. 6. Comparing fig. 7A with the target catalyst temperatures of 300C through 450C in fig. 3, the turbine 222 operating temperature is too cold. Fig. 7B shows that the SCR efficiency is less than 95%, which is undesirable. FIG. 7D shows the SCR efficiency of the thermal cycle shown in FIG. 7C. Fig. 8A and 8B show the outlet temperature of the turbine 222 versus time for various engine operating modes (thermal management calibration, Exhaust Gas Recirculation (EGR), Cylinder Deactivation (CDA)). Generally, operating the SCR 234 above 300C will take more than 600 seconds.

FIG. 9 shows a first graph of power (torque multiplied by speed) demand during a discharge cycle. The second graph shows that 20kW of power is added to the first graph. The engine runs hotter along the second graph. FIG. 10 shows a first plot of baseline torque, a second plot of new torque, and a third plot of RPM. The second plot of new torque matches the power shown in fig. 9.

Fig. 11 and 12 show a first graph of drive line power, a second graph of engine power (lower bottom) and a third graph of engine power (continuous addition). Fig. 13 discloses additional features of the present disclosure. Aftertreatment systems as discussed herein require high temperatures to operate effectively. It is important to run the engine hot. The enthalpy of the after-treatment is also important, which is essentially the temperature multiplied by the exhaust flow rate. For rapid warm-up, the engine may be run at a higher speed (such as 1600RPM or 2000RPM) in a cylinder deactivation mode where the temperature is already very hot. High engine speeds will increase the enthalpy of the catalyst. As shown in fig. 13, the aftertreatment system 214 is too cold and undesirable when the engine load is below 3 and 4 brake mean effective pressures (bar or a measure of engine torque normalized to engine displacement). However, operating the engine in a rapid heating mode, such as in a cylinder deactivation mode (described more fully below), may increase the aftertreatment temperature.

Referring now further to fig. 14A and 14B, the present disclosure may operate the engine in a cylinder deactivation mode to generate a higher engine load and, thus, an increased aftertreatment temperature. FIG. 14A shows torque versus turbine outlet temperature. Graph 320 shows the temperature of turbine 222 when in normal all-cylinder firing mode. Graph 322 shows the temperature of turbine 222 when in cylinder deactivation mode. Fig. 14B shows the relationship of torque to Brake Specific Fuel Consumption (BSFC). As shown, operating the engine 12 in the cylinder deactivation mode will advantageously increase the temperature in the aftertreatment system 214 more quickly. Further, fuel economy is improved when operating with cylinder deactivation, which provides a dual benefit.

FIG. 15 illustrates engine flywheel angular acceleration (i.e., noise and/or vibration) versus engine speed. Graph 340 shows normal firing for all cylinders (in this example six). Graph 342 shows a first cylinder deactivation mode in which three cylinders are firing (three cylinders in the CDA). As used herein, the term "firing" is used to indicate that a cylinder receives fuel and operates to provide power. Graph 344 shows a second cylinder deactivation mode in which two cylinders are firing (four cylinders in CDA). Graph 346 illustrates a third cylinder deactivation mode in which four cylinders are firing (two cylinders in CDA).

An acceptable noise and vibration range is identified between

lines

350 and 352. As shown, the second and third cylinder deactivation modes (two or four cylinders firing, respectively) are within an acceptable noise and vibration range between 600 and 750 engine RPM. Explained further, during idle, the preferred cylinder deactivation modes are the second (two-cylinder firing) and third (four-cylinder firing) cylinder deactivation modes. In this regard, these on-start cylinder deactivation patterns will affect faster warm-up of the aftertreatment, improved fuel economy (relative to normal all-cylinder firing patterns), and within an acceptable noise vibration range. Further, operating the engine in the second and third cylinder deactivation modes actually provides improved noise vibration relative to the all-cylinder firing mode. Of course, once the engine load reaches between 3 bar and 4 bar, the controller 250 no longer needs to operate in the cylinder deactivation mode because the aftertreatment system 214 has reached the desired temperature.

Fig. 16-23 illustrate additional features of the present disclosure for rapid heating using an electric regenerative accessory drive (edrad) and an electric heater (eHeater). In current prior art implementations, heating the post-treatment assembly takes about 10.5 minutes. According to the present application, the motor generator 140 may be eRAD capable of loading the engine 12 at 12kW to 25 kW. The edrad may be configured to send power to an electric exhaust heater in the exhaust. Alternatively, exhaust heating may be performed using the power plus power already in the

batteries

180, 182. In other words, the engine 12 may be operated at a certain load. The load can be run by the edrad and converted to electric heat. As a result, this will heat the exhaust gas that is run through the aftertreatment assembly 214.

Fig. 16 shows a first scenario. The objective is to achieve a predetermined amount of heat (enthalpy) in the aftertreatment component 214. The process may be completed in about 2 to 3 minutes and generate about 30kW of energy to heat the exhaust. The eRAD had an incremental shaft power of 12.5kW, with 19.2kW from the engine exhaust plus 10kW from the electric heater equaling 29.2kW of exhaust. The heating time was about 2.7 minutes to 1.3 kWh. In another scenario (fig. 17) using 25kW incremental shaft power for edra, 30.6kW from engine exhaust plus 20kW from electric heater equals 50.6kW of exhaust. The heating time was about 1.5 minutes to 1.3 kWh. It can be appreciated that with a higher kW at the aftertreatment assembly 214, for example 50.6kW (fig. 17) versus 29.2kW (fig. 16), the target of 1.3kWh is achieved more quickly. Although 1.3kWh hours is used herein, it is understood that the same principles can be used to achieve between 1kWh and 2 kWh. In addition, heater power from the battery will shorten the time. The battery can be recharged from regeneration during a previous coasting event without losing fuel.

It is also contemplated that if an electrical component is present in the exhaust stream, this may be used to spray the urea to evaporate the urea for faster injection of the urea. The present teachings may be used in conjunction with urea injection, where urea is injected onto an electric heater to aid in evaporation so that urea may be injected earlier in the cold cycle. The analysis shown in the figure is for a 6.7 liter diesel engine. It is contemplated that the present teachings may be used with other replacement diesel engines, including 15 liters. The engine 12 may be operated at high idle with Cylinder Deactivation (CDA) to almost quadruple the aftertreatment exhaust power.

Fig. 18 shows background data demonstrating that the rated power heats up in less than one minute. In the example shown, the nominal conditions have 2500RPM, 736 foot pounds of force, 710 degrees Celsius TIT, 506 degrees Celsius TOT, and 24.46 kilograms of exhaust flow per minute. When operating at rated power and speed, the SCR heats up very quickly to 200 degrees celsius at 35 seconds and 300 degrees celsius at 57 seconds. FIG. 19 shows temperature versus time for an SCR catalyst that decreases when operating at idle for an extended period of time even when cylinder deactivation numbers are added.

Referring now to fig. 19-34, additional features of the present application will be described. While the foregoing description explains systems and methods for increasing the temperature of an aftertreatment system at startup, the following description describes systems and methods for maintaining the hot temperature of an aftertreatment system after startup, such as during idle. For purposes of this disclosure, "idle" is used to mean zero engine torque, regardless of vehicle speed. Also, as used herein, "thermal temperature" is used to refer to a temperature that meets an aftertreatment system operating at a temperature that meets acceptable operation. As will be described herein, the systems and methods of the present disclosure use Cylinder Deactivation (CDA) and elevated engine idle Revolutions Per Minute (RPM) to maintain heat in the event of intermittent generator load on the engine, and/or use an electric heater to maintain the aftertreatment system at an acceptable elevated (hot) temperature after start-up, such as during idle and thereafter.

Referring to FIG. 19, the SCR catalyst will decrease in temperature when operating at idle for a longer period of time, even when Cylinder Deactivation (CDA) is added. It is desirable to avoid this temperature drop during and after operation at idle (such as during normal driving conditions) to maintain efficient operation of the aftertreatment system. While the processing system will then tend to remain hot in the CDA (such as 2 cylinder firings in this case), the final temperature will drop below the desired level (below 250 degrees celsius in this case).

Referring to fig. 20 and 21, the present application may incorporate operating the engine 502 at elevated idle speed in CDA to activate the electric heater (electric heater) 500 to produce elevated power (29 kW in this example) in the aftertreatment system (ATS)510, and thus elevated heat. Controller 250 (fig. 1) may operate in a post-processing heating mode such that ATS 510 is heated to an elevated temperature. Thereby reducing emissions based on the elevated temperature. Controller 250 is configured to heat ATS 510 to achieve an enthalpy between 1 kilowatt-hour (kWh) and 2kWh within two minutes of engine 12 starting. In the particular example shown, ATS 510 is heated to achieve an enthalpy of about 1.3 kWh. The target enthalpy is achieved by: operating the engine 12 in CDA; operating the engine 12 at an elevated idle speed; and operating the accessory device (electric heater 500) at a threshold power. By way of example only, the elevated idle speed may be between about 1200RPM for a light truck and 1500RPM for a medium truck. Those skilled in the art will appreciate that engine speeds above the calibrated idle speed for a particular engine are within the scope of the present application. By way of example, the electric heater 500 may be a 10kW electric heater. In one example, operating the engine at CDA and at elevated idle speed may provide between about 8 kilowatts and 10 kilowatts of power. Assuming an 80% conversion from mechanical to electrical can produce about 10kW from the electric heater, the electric heater 500 is operated at 12.5 kW. Additionally, an exhaust enthalpy of about 10kW may be achieved by running the engine 12 harder. In this regard, the controller 250 may operate the engine 12 and the electric heater 500 in the manner described above to achieve a power of about 29kW to meet the enthalpy target of 1.3 kWh.

In some systems, the electric heater 500 may increase the aftertreatment temperature by about 1.5 degrees celsius per second. In this regard, the aftertreatment system 510 may heat from about 250 degrees celsius to about 350 degrees celsius (using the CDA and the electric heater 500) in about one to two minutes. In the example shown, the aftertreatment system 510 may cool back to about 250 degrees Celsius in about 25 minutes (in this example, two cylinders fired in CDA without the electric heater 500). Thus, the present method provides a method of cycling in and out (on and off) using the electric heater 500 to maintain an acceptable aftertreatment temperature above 250 degrees celsius at idle not only at start-up for an extended (infinite) period of time thereafter.

Referring to FIG. 22, 19kW of heat is added, causing the aftertreatment system 510 to increase in temperature by approximately 1.5 degrees Celsius per second. Line 512 indicates the SCR temperature with CDA. In the case where the electric heater 500 is turned on, heat of 19kW may be generated. While the graph in fig. 27 is specific to heating up at start-up, various methods according to the present application use the same principle to retain heat. Line 514 represents the SCR temperature with CDA and the electric heater 500 is turned on resulting in 250 degrees celsius after 78 seconds. See arrow 516. At this time, the electric heater 500 may be turned off.

Returning to fig. 21, if the engine 502 is held at idle, the temperature of the ATS 510 will tend to eventually drop below the desired 250 degrees celsius temperature (in this example, the dwell time 520 is about 25 minutes). The present disclosure contemplates this undesirable temperature drop and turning on the electric heater 500 to re-raise the temperature in the aftertreatment system 510 during the CDA plus electric heater influence time 522 to maintain an acceptable elevated temperature for an extended (infinite) period of time even after startup. Notably, the system and method of the present application does not require the battery 530 identified in fig. 20. In other words, no 48 volt regulation is required. The voltage may be varied during heating of the electric heater 500. The electric heater 500 basically operates as a heating device and will draw any power given to it. On a highway, a truck typically has a 12 volt battery, while a bus typically has a 24 volt battery. The motor-generator is two to four times the present battery (to achieve 48 volts). Likewise, any voltage may be used for the electric heater 500. In this regard, voltages greater than 48 volts may also be acceptable for electric heaters.

FIG. 23 illustrates a Federal testing protocol for heating using another method of operating the system of the present disclosure by adding cylinder deactivation to reach 250 degrees Celsius at 249 seconds. FIG. 24 shows a Federal testing procedure showing NOx at engine start. Figure 25 shows a method of adding 10kW of heat to reach 250 degrees celsius at 104 seconds. FIGS. 26A and 26B illustrate cylinder deactivation with close-coupling catalyst enabled to allow SCR desulfation. Fig. 26C shows two exemplary catalyst configurations according to the present disclosure. Fig. 27A is a graph of nox versus time showing the effect of moving one SCR upstream to heat up faster. Fig. 27B is a graph of cumulative nox versus time showing the effect of moving one SCR upstream to heat up faster. Fig. 28 is a graph of temperature versus time for a close-coupled SCR with CDA and a current SCR without CDA. Fig. 29 is a graph of temperature versus time for a tightly coupled SCR with CDA and a current SCR without CDA showing a low duty cycle with low nitrogen oxide orders of magnitude and 5% carbon dioxide savings. FIG. 30 illustrates a table showing various methods of rapidly warming an aftertreatment system according to the present disclosure. FIG. 31 illustrates another table showing various methods of rapidly warming an aftertreatment system according to the present disclosure. FIG. 32 is a graph of engine speed and engine torque versus time using the principles of the present disclosure. FIG. 33 is a graph showing temperature and heating rate versus time for the addition of 10kW and 19kW of heat according to the present disclosure. FIG. 34 is a graph showing temperature and heating rate versus time for cold Federal test procedure heating.

Turning now to fig. 35-39, additional features will be described. FIG. 35 shows the baseline engine now during the warm-up method. The method shown in FIG. 35 requires about 60% additional engine fuel to achieve (compared to not operating the warm-up method). During warm-up, an enthalpy of about 7.4kW is provided from the engine 12 to the aftertreatment 214, which heats the aftertreatment 214 in about 10.5 minutes. For comparison (no run warm), during normal operation (fuel economy mode), enthalpy of about 2.5kW is sent from the engine 12 to the aftertreatment 214. Referring now to fig. 36, the problem addressed by the present application is illustrated. The target was to reach 1 to 2kWh for heating, using 1.3kWh as baseline. A higher level of heat is required. One method includes operating the CDA at elevated idle speed (as described above), allowing engine heat to operate at the CDA and at elevated idle speed to reach 9.2kWh (see fig. 20). This is 24% more caloric than the baseline (7.4kWh) shown in figure 35. In this regard, operation at CDA and elevated idle is an improvement over the teachings of fig. 35, but the present teachings, such as the teachings shown in fig. 37, provide even more enthalpy over a reduced period of time. As shown in fig. 38, the transmission system operates using CDA and elevated idle speed (as explained in fig. 36), but also increases engine load and electric heater 500 (fig. 20) input. In this regard, an enthalpy of 9.2kW is provided by operating the CDA and the elevated idle speed. An electric heater 500 providing 10kW is added thereto. The wire 610 electrically connects the motor generator 140 and the electric heater 500.

As shown in fig. 38, 12.5kWh is supplied to the engine 12 to operate the motor generator 140. The engine heat from operating under CDA and at elevated idle speed provides 9.2kW, the engine heat from operating the engine 12 at extra load is 10kW, and the heat from the electric heater 500 provides 10kW, all together increasing to 29.2 kW. At 29.2kW, the post-treatment 214 may be heated to 2.7 minutes.

In further implementations, CDA and accessory loads during low duty cycles may be provided, such as at the proposed regulatory low duty cycles (CARB and EPA), which is reduced by about 90% over the state of the art. Further, the present teachings may reduce the extended idle limit. Specifically, the day includes 30 gallons per hour. The present teachings can be used to achieve 10 gallons per hour in 2024 and less than 10 gallons per hour in 2027 and beyond. Extended idle speed may include about 15 minutes. Other time ranges are contemplated.

The foregoing description of these examples has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. Which can also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. A transmission system selectively coupled to an engine crankshaft of an internal combustion engine disposed on a vehicle, the transmission system comprising:

a transmission having an input shaft, a primary shaft, an output shaft, and a secondary shaft offset from the input shaft, the secondary shaft driveably connected to the first input shaft and the primary shaft;

an aftertreatment system that reduces emissions in an exhaust of the internal combustion engine;

an accessory device configured to provide power; and

a controller operating in an aftertreatment heating mode such that the aftertreatment system is heated to an elevated temperature to reduce emissions based on the elevated temperature, the controller configured to heat the aftertreatment system to achieve an enthalpy between one (1) kilowatt-hour (kWh) and two (2) kWh within two minutes of engine start-up by: (i) operating the internal combustion engine in a cylinder deactivation mode (CDA); (ii) operating the internal combustion engine at an elevated idle speed; and (iii) operating the accessory device at a threshold power.

2. The transmission system of claim 1, wherein operating the internal combustion engine at CDA and at an elevated idle speed provides between 7 kilowatts and 11 kilowatts of power.

3. The transmission system of claim 2, wherein the accessory device operates at a power between 9 kilowatts and 14 kilowatts.

4. The transmission system of claim 3, wherein:

the controller operates in the post-treatment heating mode to provide between 27 kilowatts and 33 kilowatts of power to simultaneously achieve an enthalpy between one (1) kilowatt-hour (kWh) and two (2) kWh in three minutes by:

operating the internal combustion engine under CDA and at elevated idle speed; and

operating an accessory drive at the threshold power.

5. The transmission system of claim 3, further comprising at least one battery providing voltage regulation.

6. A transmission system as claimed in claim 4, wherein the at least one battery is at least 48 volts.

7. The transmission system of claim 1, wherein the accessory device is an electric heater.

8. A transmission system as recited in claim 1 wherein the controller suspends the aftertreatment heating mode upon reaching an enthalpy between one (1) kWh and two (2) kWh until a Selective Catalytic Reduction (SCR) temperature falls below a threshold.

9. A transmission system as recited in claim 8 wherein the controller reenters an aftertreatment heating mode when the SCR temperature falls below the threshold until the aftertreatment system returns to an enthalpy between one (1) kWh and two (2) kWh.

10. A transmission system as recited in claim 1, wherein the controller is configured to heat the aftertreatment system to an enthalpy of 1.3 kWh.

11. A transmission system selectively coupled to an engine crankshaft of an internal combustion engine disposed on a vehicle, the transmission system comprising:

an electric heater disposed in the aftertreatment system;

a controller operating in an aftertreatment heating mode such that the aftertreatment system is heated to an elevated temperature to reduce emissions based on the elevated temperature, the controller operating in the aftertreatment heating mode during idle.

12. The transmission system of claim 11, wherein during an aftertreatment heating mode, the controller operates the engine in a cylinder deactivation mode (CDA) such that the aftertreatment system operates at an elevated temperature.

13. The transmission system of claim 12, wherein the controller turns on the electric heater in conjunction with operating the engine in a CDA mode during a post-processing heating mode.

14. A transmission system as recited in claim 13, wherein the controller operates in an aftertreatment heating mode for a first period of time to raise the aftertreatment system to a predetermined temperature.

15. A transmission system as recited in claim 14, wherein the predetermined temperature is about 350 degrees celsius.

16. The transmission system of claim 14, wherein the controller turns off the electric heater after the first period of time.

17. The transmission system of claim 16, wherein after the hold-down time, the controller determines that the temperature of the aftertreatment system has decreased below a desired degree celsius value and turns on the electric heater.

18. A method of operating a transmission system selectively coupled to an engine crankshaft of an internal combustion engine, the transmission system having a transmission, an aftertreatment system, and an accessory device configured to provide power, the method comprising:

determining that the aftertreatment system is operating below a threshold temperature;

operating the transmission system in a post-processing heating mode includes:

operating the internal combustion engine in a cylinder deactivation mode (CDA);

operating the internal combustion engine at an elevated idle speed; and

operating the accessory device at a threshold power;

the aftertreatment heating mode is exited upon reaching an enthalpy between one (1) kilowatt-hour (kWh) and two (2) kWh within two minutes of engine start-up.

19. The method of claim 18, wherein operating the internal combustion engine in a CDA and operating the internal combustion engine at an elevated idle speed provides between 7 kilowatts and 11 kilowatts of power.

20. The method of claim 19, wherein the accessory device operates at between 9 kilowatts and 14 kilowatts of power.

21. A method according to claim 20 wherein the controller operates in the post-treatment heating mode to provide between 27 kilowatts and 33 kilowatts of power to simultaneously achieve an enthalpy of one (1) kilowatt-hour (kWh) and two (2) kWh in three minutes by:

operating an accessory drive at the threshold power.

22. The method of claim 18, wherein the aftertreatment heating mode is exited until a Selective Catalytic Reduction (SCR) temperature falls below a threshold.

23. The method of claim 22, further comprising:

reentering the aftertreatment heating mode when the SCR temperature falls below the threshold until the aftertreatment system returns to an enthalpy between one (1) kWh and two (2) kWh.

24. The method of claim 18, wherein operating the transmission system in an aftertreatment heating mode includes heating the aftertreatment system to an enthalpy of 1.3 kWh.