Multi-layer exhaust combustor control for SCR catalyst preheating

Abstract

An exhaust control system for a vehicle includes a temperature sensor located downstream of the exhaust combustor and upstream of the SCR catalytic converter in the exhaust system. The temperature sensor is configured to generate a measurement signal indicating the temperature of the exhaust gas flowing through the exhaust system at the outlet of a DPF located downstream of the exhaust combustor. An exhaust control module is configured to: activate the exhaust combustor to heat the exhaust gas; monitor the temperature of the exhaust gas based on the measurement signal; subsequently activate the exhaust combustor and then deactivate it based on an upper threshold temperature of the exhaust gas; and subsequently deactivate the exhaust combustor and then activate it based on a lower threshold temperature of the exhaust gas. The lower threshold temperature is lower than the upper threshold temperature.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 220,100, filed July 9, 2021. The entire disclosure of the above-cited applications is incorporated herein by reference. Technical Field

[0003] This disclosure relates to exhaust control systems and methods, and more particularly to systems and methods for controlling the temperature of a selective reduction catalytic converter (SCR) and the airflow entering the exhaust system. Background Technology

[0004] The information provided in this section is intended to provide a general overview of the context of this disclosure. The work of the inventors listed herein within the scope described in this section, and aspects of this specification that would not be considered prior art at the time of submission, are neither expressly nor impliedly acknowledged as prior art to this disclosure.

[0005] Air is drawn into the engine through the intake manifold. The air is mixed with fuel from one or more fuel injectors to form an air / fuel mixture. This air / fuel mixture is burned in one or more cylinders of the engine. The combustion of the air / fuel mixture produces torque.

[0006] The exhaust gases produced by the combustion of the air / fuel mixture are expelled from the cylinders into the exhaust system. Exhaust gases from engines that burn diesel fuel with excess air may contain particulate matter (PM) and gases. The exhaust contains nitrogen oxides (NOx), such as nitric oxide (NO) and nitrogen dioxide (NO2). Exhaust treatment systems can be used to reduce the amount of NOx and PM in the exhaust.

[0007] Exhaust treatment systems may include diesel oxidation catalysts (DOC). DOC removes hydrocarbons and / or carbon oxides from exhaust gases. Exhaust treatment systems may also include diesel particulate filters (DPF), which remove particulate matter (PM) from exhaust gases. Exhaust treatment systems may also include selective catalytic reduction (SCR) catalysts. Diesel exhaust fluid (DEF) injectors inject DEF (e.g., an aqueous urea solution) into a decomposition tube or reactor located upstream of the SCR catalyst. When the DEF encounters hot exhaust gases in the decomposition tube, some water evaporates, and the urea decomposes to form ammonia. The ammonia (NH3) supplied by the DEF is absorbed by the SCR catalyst. When ammonia is present on the surface of the SCR catalyst and the catalyst is hot, NOx in the exhaust gases reacts with the ammonia to form nitrogen (N2). In this way, the amount of NOx emitted by the engine is reduced. Summary of the Invention

[0008] An exhaust control system for a vehicle includes a temperature sensor located downstream of the exhaust combustor and upstream of a selective catalytic reduction (SCR) catalyst in the vehicle's exhaust system. The temperature sensor is configured to generate a measurement signal indicating the temperature of the exhaust gas flowing through the exhaust system at the outlet of a diesel particulate filter (DPF) located downstream of the exhaust combustor. An exhaust control module is configured to: activate the exhaust combustor to heat the exhaust gas by burning air and fuel in the combustor's combustion chamber; monitor the temperature of the exhaust gas based on the measurement signal; subsequently activate the exhaust combustor and then deactivate it based on an upper threshold temperature of the exhaust gas; and subsequently deactivate the exhaust combustor and then activate it based on a lower threshold temperature of the exhaust gas. The lower threshold temperature is lower than the upper threshold temperature.

[0009] Among other features, the temperature sensor is located at the DPF outlet. The exhaust control module is configured to activate the exhaust combustor before engine start. The exhaust control module is configured to maintain the exhaust at a lower threshold temperature. After activating the exhaust combustor based on the lower threshold temperature, the exhaust control module is configured to deactivate the exhaust combustor based on an upper threshold temperature. The upper threshold temperature is greater than or equal to 300°C. The exhaust control module is configured to detect cold start conditions and, in response to detecting such cold start conditions, activate the exhaust combustor before engine start. The exhaust control module is configured to increase the engine idle speed when the exhaust combustor is activated.

[0010] Among other features, the exhaust control module is configured to: detect a cold start condition; operate the exhaust burner based on a first set of thresholds including the upper threshold temperature and the lower threshold temperature in response to detecting the cold start condition; and operate the exhaust burner based on a second set of thresholds including a second upper threshold temperature and a second lower threshold temperature in response to not detecting the cold start condition. The second upper threshold temperature is lower than the upper threshold temperature and higher than the lower threshold temperature.

[0011] Among other features, the exhaust control system further includes: an air pump configured to pump air into the combustion chamber of the exhaust combustor; a spark plug configured to ignite the air / fuel mixture in the combustion chamber of the exhaust combustor; a fuel control module configured to selectively actuate a fuel injector and initiate fuel injection when the vehicle's engine is off and before the engine is started; a pump control module configured to selectively activate the air pump when the engine is off and before the engine is started; and a spark control module configured to selectively apply electrical current to the spark plug and initiate the provision of a spark when the engine is off and before the engine is started.

[0012] Among other features, the exhaust control system further includes a diesel exhaust fluid (DEF) injector configured to inject DEF into the exhaust system upstream of the SCR catalytic converter; and a DEF control module configured to selectively actuate the DEF injector and initiate DEF injection when the vehicle's engine is off and before engine start. The opening of the exhaust combustor to heat the exhaust, the closing of the exhaust combustor, and the subsequent opening of the exhaust combustor after closing occur before engine start.

[0013] A method of operating a vehicle's exhaust control system includes receiving a measurement signal from a temperature sensor located downstream of an exhaust combustor and upstream of a selective catalytic reduction (SCR) catalyst in the vehicle's exhaust system. The measurement signal indicates the temperature of exhaust gas flowing through the exhaust system at the outlet of a diesel particulate filter (DPF) located downstream of the exhaust combustor. The method further includes: activating the exhaust combustor to heat the exhaust gas by burning air and fuel in the combustor's combustion chamber; monitoring the temperature of the exhaust gas based on the measurement signal; subsequently activating the exhaust combustor and then deactivating it based on an upper threshold temperature of the exhaust gas; and subsequently deactivating the exhaust combustor and then activating it based on a lower threshold temperature of the exhaust gas. The lower threshold temperature is lower than the upper threshold temperature.

[0014] Among other features, the temperature sensor is located at the outlet of the DPF. At least one of turning on the exhaust combustor, turning off the exhaust combustor, and turning on the exhaust combustor after turning it off occurs before engine start-up. The method further includes: turning off the exhaust combustor based on the upper threshold temperature after turning it on based on the lower threshold temperature. The method further includes: detecting a cold start condition, and turning on the exhaust combustor before engine start-up in response to detecting the cold start condition. The method further includes increasing the engine idle speed when turning on the exhaust combustor.

[0015] Among other features, the method further includes: detecting a cold start condition; operating the exhaust combustor based on a first set of thresholds including the upper threshold temperature and the lower threshold temperature in response to detecting the cold start condition; and operating the exhaust combustor based on a second set of thresholds including a second upper threshold temperature and a second lower threshold temperature in response to not detecting the cold start condition. The second upper threshold temperature is less than the upper threshold temperature and greater than the lower threshold temperature.

[0016] The further applicability of this disclosure will become clear from the detailed description, claims, and drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0017] This disclosure will be more fully understood from the detailed description and the accompanying figures, in which:

[0018] Figure 1 This is a functional block diagram of an example engine system;

[0019] Figure 2 This is a functional block diagram of an example exhaust control system;

[0020] Figure 3 and Figure 4 This is a functional block diagram of an example air valve connection;

[0021] Figure 5 It is a flowchart depicting an example method for controlling DEF injection, heating, and airflow before engine start-up;

[0022] Figure 6 This is a flowchart depicting an example method for controlling an air valve; and

[0023] Figure 7A , Figure 7B and Figure 7C This is a flowchart depicting an example multi-layer threshold control method for an exhaust burner.

[0024] In the accompanying drawings, reference numerals may be used repeatedly to identify similar and / or identical elements. Detailed Implementation

[0025] The control module controls the injection of diesel exhaust fluid (DEF) into the exhaust system, upstream of the selective catalytic reduction (SCR) catalyst. The SCR catalyst receives exhaust gas from the vehicle's engine. The exhaust gas contains nitrogen oxides (NOx). The DEF contains urea and water. Heat from the exhaust gas decomposes the urea from the DEF into ammonia (NH3). The SCR catalyst stores the ammonia. The ammonia reacts with NOx in the exhaust gas, thereby reducing the amount of NOx emitted from the SCR catalyst.

[0026] Engines may produce high levels of NOx during startup. However, the amount of ammonia stored in the SCR (by which it is stored) during startup may be low. The exhaust temperature during engine startup may be too low to process the DEF injected into the decomposer into ammonia. Therefore, the vehicle's NOx output may be relatively high after engine startup.

[0027] Before and / or during engine start-up, an exhaust combustor can be used to heat the SCR catalytic converter. The combustor burns air and fuel to heat the SCR catalytic converter. Combustion can be initiated by a spark plug or another type of ignition device. Heating the SCR catalytic converter prepares it to store ammonia so that it reacts with NOx more quickly than without heating, thus reducing the vehicle's NOx output after engine start-up. Under certain conditions, DEF injection can be initiated before engine start-up to further reduce the vehicle's NOx output after engine start-up.

[0028] Accordingly, under certain conditions, the exhaust combustor can be used to preheat the SCR catalytic converter (i.e., before engine start). Conversely, the exhaust combustor can be used during engine start-up under cold start conditions (i.e., upon receiving an engine start signal under cold start conditions). Under cold start conditions, it is desirable to heat the SCR catalytic converter and other components of the exhaust treatment system as quickly as possible. Therefore, the exhaust combustor can be controlled to heat the exhaust system to a relatively high temperature to ensure that it does not shut off during cold start conditions until the SCR catalytic converter is sufficiently heated.

[0029] Following a cold start, the engine can continue to operate at low load for a period of time, resulting in relatively cold exhaust and causing the SCR catalyst to operate at a suboptimal temperature. Furthermore, using an exhaust combustor to heat the exhaust becomes necessary, but this consumes additional fuel, reducing fuel economy and increasing CO2 production. The multi-layer threshold exhaust combustor control system and method according to this disclosure are configured to regulate the exhaust combustor to minimize fuel consumption and maintain the SCR catalyst temperature, thereby optimizing NOx conversion during low-load operation. While an exhaust combustor has been described, the principles of this application can also be implemented using other types of exhaust heaters (including, but not limited to, high-power electric heaters).

[0030] Now for reference Figure 1 The diagram presents a functional block diagram of an example engine system 100. Engine 102 generates propulsion torque for the vehicle. The vehicle may have a Class 4, Class 5, Class 6, Class 7, or Class 8 rating, such as those from the U.S. Department of Transportation (DOT). The vehicle rating is based on the Gross Vehicle Rated Weight (GVWR). Generally, GVWR increases with the rating and vice versa. Although engine 102 is shown and will be discussed as a diesel engine, engine 102 could be another suitable type of engine. One or more electric motors (or motor-generators) may additionally generate propulsion torque.

[0031] Air is drawn into engine 102 through intake manifold 104. One or more fuel injectors (e.g., fuel injector 110) inject fuel, which mixes with air to form an air / fuel mixture. The air / fuel mixture is burned within cylinders (e.g., cylinder 114) of engine 102. Fuel injector 110 injects fuel directly into cylinder 114. The heat from compression within cylinder 114 can ignite combustion within cylinder 114. ECM 108 controls the fuel injection through fuel injector 110. Although engine 102 is depicted as containing one cylinder, engine 102 may contain more than one cylinder. Each cylinder may be equipped with one fuel injector.

[0032] Exhaust gas is discharged from engine 102 to exhaust system 120. The exhaust gas may contain particulate matter (PM) and nitrogen oxides (NOx), such as nitric oxide (NO) and nitrogen dioxide (NO2). Exhaust system 120 includes a treatment system to reduce the corresponding amounts of NOx and PM in the exhaust gas.

[0033] The exhaust system 120 includes a diesel oxidation catalyst (DOC) 122, a diesel particulate filter 126, and one or more selective catalytic reduction (SCR) catalysts, such as SCR catalyst 124-1 and SCR catalyst 124-2 (collectively referred to as "SCR catalyst 124"). SCR catalyst 124-1 may, for example, comprise iron zeolite or another suitable type of SCR catalyst. SCR catalyst 124-2 may comprise copper zeolite or another suitable type of SCR catalyst. In various embodiments, SCR catalysts 124-1 and 124-2 may be implemented within the same housing.

[0034] Exhaust flows from engine 102 to DOC 122. Exhaust from DOC 122 flows to DPF 126. DPF 126 filters particulate matter from the exhaust. In various embodiments, DPF 126 and DOC 122 can be implemented within the same housing. Although an example is shown with DPF 126 located downstream of DOC 122, DPF 126 can alternatively be located upstream of DOC 122. Exhaust flows from DPF 126 to SCR catalytic converter 124.

[0035] Diesel exhaust fluid (DEF) injector 130 injects DEF into the exhaust system 120 upstream of the SCR catalyst 124. For example, DEF injector 130 may inject DEF into a decomposer 131, where water in the injected DEF evaporates and urea decomposes and hydrolyzes into NH3. Decomposer 131 may also be referred to as a reactor. For example only, decomposer 131 may be located between DOC 122 and the SCR catalyst 124. DEF contains urea (e.g., CO(NH2)2) and water. Before injection, DEF is stored in a DEF tank 132. DEF pump 134 draws DEF from DEF tank 132 and pumps DEF to DEF injector 130.

[0036] The exhaust control module 138 controls the actuation (e.g., opening and closing) of the DEF injector 130, and thus controls the injection of DEF into the exhaust system 120. The exhaust control module 138 can also control the operation of the DEF pump 134, for example, to maintain a predetermined pressure at the DEF input to the DEF injector 130, as in... Figure 2 A more detailed description is provided below.

[0037] When the engine is running, normal burner and DEF control can be used. When the engine is running, urea from the DEF injected by DEF injector 130 reacts with hot exhaust gas to produce ammonia, which is then supplied to the SCR catalytic converter 124. Heat evaporates water in the DEF, and ammonia (NH3) is supplied to the SCR catalytic converter 124.

[0038] SCR catalyst 124 stores (i.e. absorbs) ammonia supplied by DEF. SCR catalyst 124 catalyzes the reaction between the stored ammonia and NOx passing through SCR catalyst 124.

[0039] The amount of ammonia stored in the SCR catalyst 124 can be referred to as the current storage amount. The current storage amount can be expressed as the mass of ammonia (e.g., grams), the number of moles of ammonia, or another suitable measure of the amount of ammonia stored by the SCR catalyst 124.

[0040] The percentage of NOx input to the SCR catalyst 124 that is removed from the exhaust gas via reaction with ammonia can be referred to as the NOx conversion efficiency. The NOx conversion efficiency depends on the current storage level of the SCR catalyst 124. By way of example only, the NOx conversion efficiency can increase with increasing current storage level of the SCR catalyst 124, and vice versa.

[0041] However, the current storage capacity of the SCR catalyst 124 is limited to the maximum ammonia flow rate. This maximum ammonia flow rate is referred to as the maximum storage capacity of the SCR catalyst 124. Maintaining the current storage capacity of the SCR catalyst 124 near its maximum storage capacity ensures the removal of the maximum possible amount of NOx from the exhaust gas. In other words, maintaining the current storage capacity close to the maximum storage capacity ensures the achievement of the maximum possible NOx conversion efficiency.

[0042] However, there is an inverse relationship between the maximum storage capacity and the temperature of the SCR catalyst 124. More specifically, during engine operation, the maximum storage capacity decreases as the SCR temperature increases, and vice versa.

[0043] Ammonia reacts with NOx to produce nitrogen and water. Other components of the exhaust gas (such as oxygen (O2)) may also participate in the reaction between ammonia and NOx.

[0044] One or more sensors may be implemented in the exhaust system 120, such as one or more NOx sensors, one or more temperature sensors, one or more oxygen sensors, and / or one or more other types of sensors. For example, a temperature sensor may measure the temperature of the SCR catalyst 124. In various embodiments, the temperature of the SCR catalyst 124 may be estimated based on one or more exhaust temperatures. Other example types of sensors include mass airflow rate (MAF) sensors, recirculated exhaust flow rate (EFR) sensors, intake air temperature (IAT) sensors, coolant temperature sensors, manifold absolute pressure (MAP) sensors, engine speed (RPM) sensors, exhaust pressure sensors, and / or one or more other suitable sensors. Figure 1 The 150 are displayed uniformly in the middle.

[0045] The burner 154 can also be connected to the exhaust system 120, such as upstream of the DOC 122 and DPF 126. The burner 154 may include a fuel injector 158, a spark plug 162, and an air pump 166. While an example of a burner 154 including a spark plug has been provided, this application is also applicable to other types of igniters and ignition devices.

[0046] When activated, air pump 166 pumps air into the combustion chamber (within flame sheath 156) and into the exhaust system 120. Fuel injector 158 injects fuel (e.g., diesel fuel) into the combustion chamber. The fuel mixes with the air from air pump 166. Spark plug 162 generates a spark in the combustion chamber. The spark ignites the air and fuel from fuel injector 158 and air pump 166. Flame sheath 156 is configured to protect the flame in the combustion chamber from being blown out, for example, from being blown out by exhaust gas from engine 102 during engine operation.

[0047] The combustion of air and fuel produces hot gases that can be used to heat one or more components of the exhaust system 120 and / or for one or more other purposes. The exhaust control module 138 controls fuel injection via the fuel injector 158, spark generation via the spark plug 162, and the operation of the air pump 166. In various embodiments, the exhaust control module 138 can control the speed of the air pump 166 regardless of whether the burner 154 is receiving fuel for combustion. When receiving fuel, the exhaust control module 138 can control the speed of the air pump 166 to achieve a desired air-fuel ratio. If the burner 154 is operating while the engine is running, the exhaust control module 138 can operate the burner 154 across the entire air-fuel ratio range capable of achieving stable combustion.

[0048] Air pump 166 also pumps air to air valve (V) 170. Air valve 170 directs the airflow to a second position, such as around the flame sheath 156. The air flowing around the flame sheath 156 can cool the flame sheath 156 and extend its lifespan. In various embodiments, the second position can be between the flame sheath 156 and the exhaust pipe 174 connected to the burner 154, for example... Figure 3 As shown at position 175. Alternatively, air valve 170 can output air directly from air pump 166 to exhaust pipe 174, for example... Figure 4 As shown in the diagram. The exhaust control module 138 also controls the actuation of the air valve 170.

[0049] When engine 102 is running, engine control module (ECM) 108 controls the torque output of engine 102. ECM 108 also controls the starting and stopping of engine 102. ECM 108 can start engine 102, for example, in response to user actuation of a combination of one or more user input devices (e.g., the vehicle's ignition button or switch) and / or one or more user input devices of a key card. ECM 108 can shut down engine 102, for example, in response to user actuation of a combination of one or more user input devices (e.g., the vehicle's ignition button or switch) and / or one or more user input devices of a key card.

[0050] As discussed above, the exhaust control module 138 can control the injection of DEF through the DEF injector 130. By way of example only, the exhaust control module 138 can control the timing and rate of DEF injection. By controlling the DEF injection, the exhaust control module 138 controls the supply of ammonia to the SCR catalyst 124 and the current storage level of the SCR catalyst 124.

[0051] The rate at which DEF is injected can be referred to as the DEF injection rate (e.g., g / s). The rate at which ammonia is supplied to the SCR catalyst 124 can be referred to as the ammonia supply rate (e.g., g / s). The exhaust control module 138 can determine a target supply rate for supplying ammonia to the SCR catalyst 124, determine a target DEF injection rate to achieve the target supply rate, and control the injection of DEF at the target DEF injection rate.

[0052] The vehicle may include a wireless transceiver module 180 configured to wirelessly communicate with a mobile device, such as a mobile device 182 (e.g., a key card, cellular phone, etc.), using a communication protocol. The communication protocol may be Bluetooth (BT) (partially defined by IEEE 802.15), WiFi (partially defined by IEEE 802.11), or another suitable communication protocol. The wireless transceiver module 180 wirelessly communicates via one or more antennas (e.g., antenna 184).

[0053] In response to engine start-up, the vehicle's NOx emissions may be relatively high. In some examples, the SCR catalytic converter 124 may be heated before engine start-up, such as when a mobile device communicating with the wireless transceiver module 180 changes from a distance greater than a predetermined distance from the vehicle to a distance less than a predetermined distance. Another indicator of engine start-up may be, for example, the unlocking of one or more door locks of the vehicle. In various embodiments, the wireless transceiver module 180 may unlock one, more, or all of the vehicle's door locks in response to receiving user input from the mobile device.

[0054] The wireless transceiver module 180 can determine the distance between the mobile device and the vehicle, for example, using triangulation and multiple antennas of the vehicle. For instance, the wireless transceiver module 180 can determine the distance from the mobile device to an antenna based on the relative signal strength indicator (RSSI) of the signal between the mobile device and an antenna. The RSSI can increase as the distance decreases, and vice versa. While an example of RSSI is provided, another suitable signal strength indicator can also be used. The wireless transceiver module 180 can determine the distance between the mobile device and the vehicle based on the location of the antenna and the distance between the mobile device and the antenna (e.g., using an equation or lookup table).

[0055] Preheating before engine start is performed by operating the burner 154 before engine start. The exhaust control module 138 can control the burner 154 (supplying fuel and / or air from the air pump 166 via the fuel injector 158), for example, by using a lean air / fuel mixture for heating. During heating, the air valve 170 can be closed so that no air flows through the air valve 170 to the second position. When the engine 102 is running after start-up, the exhaust control module 138 can partially or fully open the air valve 170 to allow air to flow from the air pump 166 to the second position.

[0056] If the temperature of the SCR catalyst 124 exceeds a predetermined temperature during preheating before engine start, the exhaust control module 138 can initiate DEF injection. The predetermined temperature corresponds to the temperature at which DEF can decompose into ammonia. Preheating the SCR catalyst 124 can reduce NOx emissions after engine start because DEF injection can begin more quickly after engine start. DEF injection before engine start can further reduce NOx emissions after engine start.

[0057] At the start of a cold start, the combustor 154 can operate at a relatively high threshold (e.g., 300°C or higher) to heat the SCR catalyst 124 as quickly as possible. In this way, during cold start conditions, the combustor 154 will not be shut off until the SCR catalyst 124 is sufficiently heated. However, following a cold start, the engine 102 can continue to operate at low load for a period of time, resulting in relatively cold exhaust and causing the SCR catalyst 124 to operate at a suboptimal temperature. Furthermore, using the combustor 154 to heat the exhaust consumes additional fuel, thereby reducing fuel economy and increasing carbon dioxide production. The exhaust control module 138 according to this application is configured to implement multi-level threshold control of the combustor 154. For example, the exhaust control module 138 is configured to control the combustor 154 (i.e., selectively turn the combustor on and off) in response to a measurement signal 176 indicating the temperature downstream of the DPF 126 (e.g., the exhaust temperature measured using a sensor 178 located at the outlet of the DPF 126).

[0058] In one example, the exhaust control module 138 may control the combustor 154 based on a single temperature threshold (i.e., the exhaust control module 138 implements single-layer threshold control). For example, the combustor 154 is turned on until signal 176 indicates that the temperature downstream of DPF 126 reaches a predetermined threshold (e.g., 200°C), and then the exhaust control module 138 turns off the combustor 154. In this example, the threshold is selected to balance NOx conversion, fuel consumption, and CO2 production. If a higher threshold is selected, NOx conversion increases, as do fuel production and CO2 production. Conversely, if a lower threshold is selected, NOx conversion decreases, as do fuel production and CO2 production. In other words, as the threshold decreases and the combustor 154 turns off more quickly, the average temperature of DOC 122 and DPF 126 decreases (corresponding to a lower temperature for the SCR catalyst 124). Accordingly, while lowering the threshold saves fuel and reduces CO2 emissions, the NOx conversion efficiency of the SCR catalyst 124 is lower.

[0059] In another example, the exhaust control module 138 of this application is configured to control the burner 154 based on multiple (e.g., two or more) temperature thresholds to implement multi-level threshold control. In this example, the exhaust control module 138 initially (e.g., before and / or after a cold start) controls the burner 154 until an upper threshold (e.g., 300°C or higher, such as 400°C) is reached, and then shuts off the burner 154. After the burner 154 is shut off, the exhaust control module 138 continues to monitor the decreasing measured temperature until the temperature reaches or decreases below a lower threshold (200°C), and then restarts the burner 154.

[0060] During operation of engine 102, exhaust control module 138 continues to maintain combustor 154 according to a lower threshold. For example, when the measured temperature reaches or drops below the lower threshold, exhaust control module 138 activates combustor 154. In this way, operation of combustor 154 is maintained during prolonged low-load operation of engine 102.

[0061] The upper threshold of multi-layer threshold control (e.g., 300°C) can be selected to be greater than the threshold used for single-layer threshold control (200°C). Accordingly, combustor 154 can operate for a longer initial duration. However, because the exhaust flow rate is relatively low before and during cold start, the heat generated by combustor 154 may not be effectively forced downstream of combustor 154 and into SCR catalyst 124, which may lead to overheating of combustor 154 and inefficient cold start NOx conversion. Accordingly, in some examples, exhaust control module 138 can be further configured to increase the idle speed of engine 102 when combustor 154 is open during cold start operation. Increasing the idle speed of engine 102 increases the exhaust flow to move the heat generated by combustor 154 downstream, thereby preventing combustor 154 from overheating and optimizing NOx conversion.

[0062] In another example, exhaust control module 138 is configured to implement hysteresis control to operate burner 154 between an upper threshold and a lower threshold. For example, instead of turning on burner 154 until the upper threshold is reached and then maintaining burner 154 at the lower threshold, exhaust control module 138 can operate burner 154 between the lower and upper thresholds. In this example, exhaust control module 138 initially operates burner 154 until the upper threshold (e.g., 300°C) is reached, and then turns off burner 154. When the measured temperature drops to the lower threshold (e.g., 200°C), exhaust control module 138 turns burner 154 on again. In this way, because a higher average exhaust temperature (e.g., between the lower and upper thresholds, such as 240°C to 260°C) is maintained compared to simply maintaining the temperature at the lower threshold, more heat is stored in DOC 122 and DPF 126, and NOx conversion increases.

[0063] In the example above, following a cold start and when engine 102 is not operating under sustained low load conditions, the exhaust gas may reach a temperature sufficient to prevent combustor 154 from opening. For example, during normal operation of engine 102, even when combustor 154 is off, the measured exhaust temperature indicated by signal 176 may reach and exceed a lower threshold. In this way, combustor 154 operates only when it is necessary to maintain SCR catalyst 124 at a sufficient temperature to meet the desired NOx conversion level.

[0064] In another example, exhaust control module 138 is configured to operate burner 154 according to more than two thresholds, two or more sets of different upper and lower thresholds, etc. For example, during cold start conditions, exhaust control module 138 may turn on burner 154 until an upper threshold (e.g., 300°C) is reached, and then operate burner between a lower threshold (e.g., 200°C) and an intermediate threshold (e.g., 250°C). Exhaust control module 138 may also operate burner 154 according to a first set of thresholds (e.g., 200°C and 300°C) when a cold start condition is detected (e.g., engine coolant is below a predetermined threshold, such as 35°C), and operate burner according to a second set of thresholds (e.g., 200°C and 250°C) or a single threshold (e.g., maintaining the measured temperature at or near a single temperature, such as 200°C) when no cold start condition is detected. For example, when coolant temperature and / or other factors indicate that engine 102 has been recently operated, a cold start condition may not be detected, which corresponds to a warm start or hot start.

[0065] The exhaust control module 138 can selectively switch between different sets of thresholds based on various detected conditions. For example, during sustained low-load operation (e.g., when the burner 154 is not open and the load is insufficient to maintain the desired temperature), the measured temperature may drop below the lower threshold, causing the exhaust control module 138 to open the burner 154 until the upper threshold of 300°C is reached. Therefore, the exhaust temperature can cycle through several relatively large temperature ranges (i.e., between 200°C and 300°C). If the exhaust temperature consistent with the lower threshold is sufficient to maintain the desired NOx conversion level, the additional fuel consumption and CO2 generation associated with repeatedly opening the burner 154 to reach the upper threshold are unnecessary.

[0066] Accordingly, the exhaust control module 138 can switch to a different set of thresholds during continuous low-load operation (e.g., low-load operation lasting longer than a predetermined period (e.g., five minutes) in response to the burner 154 being turned on a predetermined number of times within a predetermined period). For example, for the second set of thresholds, the lower threshold can be lowered (e.g., to 225°C and 180°C respectively), and / or the upper threshold can be lowered (e.g., to 225°C, to 250°C, etc.). Lowering the lower threshold reduces the activation frequency of the burner 154. As a result, the frequency of the burner 154's on and off cycles decreases, and the duration of the burner 154's on operation is reduced.

[0067] Although sensor 178 is positioned at the outlet of DPF 126 as shown in the figure, in other examples, sensor 178 may be positioned at other locations (e.g., at the inlet of DOC 122, between DOC 122 and DPF 126, etc.). For example, DOC 122 and DPF 126 are used as a heat storage device. Accordingly, the temperature measured at sensor 178 at the outlet of DPF 126 corresponds to the combined heat capacity of DOC 122 and DPF 126. Conversely, if sensor 178 is positioned at the outlet of DOC 122 (i.e., between DOC 122 and DPF 126), then the measured temperature will correspond to the ratio of the length of DOC 122 to the combined length of DOC 122 and DPF 126. For example, the temperature measured at the outlet of DOC 122 may correspond to 1 / 3 of the combined heat capacity of DOC 122 and DPF 126. Accordingly, positioning sensor 178 at the outlet of DOC 122 may cause burner 154 to turn on and off more frequently, while reducing the amplitude of the heat wave passing through exhaust system 120.

[0068] Furthermore, the values ​​selected for the upper and lower thresholds can vary based on the positioning of sensor 178. For example, if the positioning is at the exit of DOC 122 (rather than as...) Figure 1 If the upper threshold is increased (as shown at the outlet of DPF 126), then the desired heat transfer to the components downstream of DOC 122 can be achieved. Conversely, the lower threshold can be increased to reduce the on / off cycle frequency of burner 154.

[0069] Figure 2 This is a functional block diagram of an example exhaust control system 200, which includes an exhaust control module 138 and a burner 154. A target module 204 determines a target DEF metering rate, for example, based on a target (ammonia) supply rate for the SCR catalyst 124. The target module 204 can determine the target DEF injection rate using either a lookup table or an equation relating the target supply rate to the target DEF injection rate. The target DEF injection rate corresponds to the DEF injection rate to achieve the target ammonia supply rate to the SCR catalyst 124. The target supply rate corresponds to the target rate at which ammonia is supplied to the SCR catalyst 124.

[0070] DEF control module 208 controls the opening and closing of DEF injector 130 to control injection and achieve a target DEF injection rate. DEF control module 208 can open DEF injector 130 by applying power (e.g., from a battery). DEF control module 208 can close DEF injector 130 by disconnecting it from power. DEF control module 208 can use pulse width modulation (PWM) control or another suitable type of control to control DEF injector 130.

[0071] The target module 204 may determine the target supply rate, for example, based on the target current storage level of the SCR catalyst 124, the current storage level of the SCR catalyst 124, and / or one or more other parameters. The target module 204 may determine the target supply rate, for example, using one of an equation or a lookup table that relates the target current storage level, the current storage level, and / or other parameters to the target supply rate.

[0072] When the engine is running, the target module 204 can determine the target current storage level, for example, based on a predetermined percentage of the current maximum storage capacity of the SCR catalyst 124. The predetermined percentage can be, for example, 90%, 95%, or another suitable value less than or equal to 100% and greater than or equal to 50%. A predetermined percentage of 100% can, for example, increase the likelihood of ammonia leakage in response to an increase in temperature, which leads to a reduction in the maximum storage capacity and may cause ammonia to desorb from the SCR catalyst 124.

[0073] Storage capacity module 212 can determine the current maximum storage capacity based on the current temperature of SCR catalyst 124. For example, storage capacity module 212 can increase the current maximum storage capacity as the temperature decreases, and vice versa. Storage capacity module 212 can determine the current maximum storage capacity using either a lookup table or an equation relating the temperature of SCR catalyst 124 to the maximum storage capacity.

[0074] When engine 102 is shut off before engine start, target module 204 can set the target storage level as a percentage of the maximum storage capacity of SCR catalyst 124 at a specified temperature. For example, target module 204 can set the target current storage level to 100% of the maximum storage capacity of SCR catalyst 124 at 150 degrees Celsius. While these examples are provided, other percentages, temperatures, and target current storage values ​​can be used. Copper-zeolite SCR catalysts can have a storage level of approximately 3 grams per liter of substrate volume.

[0075] Storage module 216 can determine the current (ammonia) storage level of SCR catalyst 124. When engine 102 shuts down in response to engine shutdown, engine 102 does not output NOx. However, the current storage level of SCR catalyst 124 at engine shutdown will be known because storage module 216 tracks the current storage level when engine 102 is on. When DEF injection is performed at engine 102 shutdown, the current storage level increases.

[0076] Storage module 216 can receive the current ammonia supply rate (e.g., grams per second). For example, storage module 216 can receive a target supply rate from target module 204. Storage module 216 can (mathematically) integrate the ammonia supply rate for each predetermined time period to determine the mass of ammonia supplied to SCR catalyst 124. When DEF injection is performed, storage module 216 can add each mass of ammonia to the (current) current storage level to update the current storage level over time.

[0077] Temperature control module 220 controls the operation of air pump 166, air valve 170, fuel injector 158, and spark plug 162. More specifically, pump control module 224 controls the operation of air pump 166, and fuel control module 228 controls the operation of fuel injector 158. Spark control module 232 controls spark plug 162, and valve control module 236 controls the actuation of air valve 170.

[0078] According to this application, the temperature control module 220 is configured to further control the burner 154 (e.g., fuel control module 228, spark control module 232, fuel injector 158, spark plug 162, etc.) based on a signal 176 indicating the measured temperature of the exhaust gas. For example, the temperature control module 220 is configured to selectively turn the burner 154 on and off based on the signal 176 and upper and lower temperature thresholds, different groups of upper and lower temperature thresholds, etc., as described in more detail above.

[0079] In some examples, different sets of temperature thresholds can be based on measurements received from sensors at different locations. For example, under cold-start conditions, burner 154 can be controlled based on a first set of temperature thresholds and signal 176 received from sensor 178. In this way, burner 154 can be controlled based on the temperature of the structure with a relatively large heat capacity (i.e., DPF 126) and the associated hysteresis during cold-start conditions to ensure that the desired high temperature is reached. Conversely, burner 154 can be controlled after cold start based on a second set (e.g., lower limit) of temperature thresholds and signal 186 received from sensor 188 (e.g., located at the outlet of DOC 122). In this way, burner 154 can be controlled after cold start based on the temperature of the structure with a smaller heat capacity (i.e., DOC 122).

[0080] As described above, ECM 108 controls engine start. Before ECM 108 starts engine 102, start module 240 can selectively generate a start signal indicating an impending engine start. For example, start module 240 can generate a start signal when the mobile device is within a predetermined distance (e.g., 20 feet) of the vehicle. The wireless transceiver module 180 can determine the distance between the mobile device and the vehicle, as discussed above. Additionally or alternatively, start module 240 can generate a start signal in response to the unlocking of one or more doors of the vehicle. Additionally or alternatively, start module 240 can generate a start signal based on the current time, such as when the current time reaches a predetermined time when engine start typically occurs (e.g., daily, such as on a weekday).

[0081] When a start signal is generated, pump control module 224 activates air pump 166. Additionally, fuel control module 228 initiates fuel injection via fuel injector 158, and spark control module 232 begins providing a spark to ignite the air and fuel. Additionally, valve control module 236 opens air valve 170 to a predetermined open position, allowing some air from air pump 166 to flow to a second position, such as around flame sheath 156. The predetermined open position can be partially or fully open. To provide a predetermined lean air / fuel mixture relative to the stoichiometric air / fuel mixture upon the generation of the start signal, at least one of the following occurs: (a) fuel control module 228 can control (e.g., reduce) the fuel supply, and (b) valve control module 236 can open air valve 170. Providing a lean air / fuel mixture can, for example, maximize the heating of SCR catalytic converter 124 before engine start.

[0082] The engine status signal indicates whether the engine 102 is running (started), started (activated), or shut down (closed). The ECM 108 can set the engine status signal and output the engine status signal to other modules.

[0083] Before engine start-up (when a start signal is generated, but before engine start-up is initiated by ECM 108), when the temperature of SCR catalyst 124 is higher than a predetermined temperature, DEF control module 208 can begin DEF injection. As described above, when the temperature is higher than the predetermined temperature, the injected DEF can decompose into ammonia gas for storage by SCR catalyst 124. For example, target module 204 can set a target supply rate as described above to adjust the current storage level of SCR catalyst 124 to or to the maximum storage capacity or a predetermined percentage of the maximum storage capacity before engine start-up.

[0084] When the engine status indicates that engine 102 is running, such as after engine start-up, valve control module 236 can close air valve 170 to the fully closed position, allowing all air output from air pump 166 to flow into flame sheath 156. Normal control of burner 154 and DEF injection can then be performed.

[0085] Regarding setting the target DEF injection rate, the target module 204 can first determine the amount of NH3 to be input to achieve the target current storage level based on the difference between the current storage level and the target current storage level. The target module 204 can then determine the amount of DEF to be injected into the decomposer tube 131 based on the amount of NH3 to be input, to provide the required amount of NH3. The target module 204 can set the target injection rate based on various factors (e.g., over time), such as the SCR temperature or the temperature of the air leaving the DOC and DPF after the air pump 166 is turned on. For example, if the SCR temperature is too high or the temperature of the gas leaving the DPF 126 is too low, DEF injection can be deactivated. The SCR temperature can be determined, for example, based on the average exhaust temperature entering and exiting the SCR catalyst 124. The exhaust temperature sensor operates based on the flowing gas, so the air pump 166 can operate and DEF injection can be deactivated for a certain period when the exhaust temperature sensor is ready.

[0086] When the temperature of the SCR catalyst 124 is below a predetermined temperature, the target module 204 can determine the enthalpy rate of the (hot) air from the DPF 126 and entering the decomposition tube 131. This enthalpy rate may need to be X times the enthalpy consumption rate corresponding to the maximum permissible DEF metering rate. The processing of DEF within the decomposition tube 131 is endothermic because each step in the process is endothermic, such as raising the temperature of water from 25°C to 100°C, evaporating water, sublimating solid urea into gaseous urea, and decomposing urea into NH3 and HNCO, etc. Therefore, the DEF metering rate can have an associated DEF enthalpy consumption rate.

[0087] The difference between the enthalpy rate of the hot airflow generated by the air pump and the factor X can limit the maximum enthalpy consumption rate, and thus limit the corresponding maximum DEF metering rate. Next, the target module 204 can set a target DEF injection rate to result in metering at the maximum enthalpy consumption rate.

[0088] The factor (value) X can be calibrated based on one or more characteristics of the decomposition tube 131. When DEF is injected into the decomposition tube 131, droplets can impact surfaces. These surfaces are heated by the hot gas flow and cooled by the impacting droplets. If a wall film forms on the surface of the decomposition tube 131, the temperature will decrease, for example, due to the evaporation of water in the DEF droplets. The target module 204 can limit the target DEF injection rate so that the enthalpy rate of the air is sufficient to maintain the surface heat of the decomposition tube 131 and prevent wall film formation.

[0089] If the current storage level reaches the target storage level before engine start, then DEF injection and air pump 166 can be deactivated. If burner 154 is already operating (providing heat), then that burner should also be deactivated.

[0090] Figure 5 This is a flowchart depicting an example method 500 for controlling DEF injection, heating, and airflow before engine start-up. Control begins at 504, where target module 204 and temperature control module 220 determine whether engine 102 is off, for example, whether an engine status signal indicates that engine 102 is off. If 504 is true, then control continues at 508. If 504 is false, then control can remain at 504.

[0091] At point 508, the wireless transceiver module 180 determines whether a mobile device associated with the vehicle is within a predetermined distance of the vehicle. If 508 is true, then the starter module 240 generates an engine start signal, and control continues at 512. If 508 is false, then control can return to 504. Besides the mobile device being outside or alternatively within the predetermined distance of the vehicle, this application also applies to other predictive indicators of engine start, such as the unlocking of vehicle doors, the current time being within a predetermined time period when the vehicle is typically started, etc.

[0092] At 512, temperature control module 220 determines whether an engine start signal is being generated. If 512 is true, control continues at 516. If 512 is false, control returns to 504. At 516, temperature control module 220 activates or maintains the burner 154. More specifically, pump control module 224 activates or maintains the air pump 166. Fuel control module 228 activates or maintains the fuel supply via fuel injector 158. Spark control module 232 activates or maintains the spark from spark plug 162. At 516, valve control module 236 also opens valve 170 to allow air to flow to a second position. To provide a lean air / fuel mixture to burner 154, at least one of fuel control module 228 and valve control module 236 adjusts the opening of the fuel supply and / or air valve, respectively.

[0093] At point 520, the temperature control module 220 and the target module 204 determine whether the engine status is set to engine start state. When the engine status is set to engine start state, the ECM 108 starts (starts) the engine 102. If 520 is true, then control can end. If 520 is false, then control can continue at point 524.

[0094] At 524, target module 204 can determine whether the temperature of SCR catalyst 124 is higher than a predetermined temperature. If 524 is true, then control can continue to 532. If 524 is false, then target module 204 can set the target DEF injection rate to zero, and at 528, DEF injection can be disabled, and control can return to 504.

[0095] At 532, the target module 204 determines a target storage level (e.g., setting the target storage level as a predetermined storage level for engine start-up), and the storage module 216 updates the current storage level of the SCR catalyst 124. The storage module 216 can update the current storage level by integrating the (current) target supply rate to determine the mass of ammonia supplied to the SCR catalyst and adding the determined mass to the current storage level. As discussed above, the target module 204 determines the target supply rate and the target DEF injection rate. At 536, the DEF control module 208 controls the DEF injector 130 to inject DEF based on or at the target DEF injection rate.

[0096] At 540, temperature control module 220 and target module 204 determine whether the current storage level has been reached (e.g., greater than or equal to) the target storage level. If 540 is true, then the DEF injector and burner 154 can be deactivated, and control can end. If 540 is false, then control can return to 504.

[0097] Figure 6 This is a flowchart depicting an example method 600 for controlling air valve 170. Control begins at 604, where valve control module 236 determines whether the engine state is set to off and whether engine 102 is shut down. If 604 is true, then valve control module 236 can close air valve 170 or maintain the air valve closed, and control can continue to 608. In various embodiments, air valve 170 may be a normally closed valve and biased closed. If 604 is false, then control can remain at 604.

[0098] At 608, valve control module 236 determines whether an engine start signal has been generated. If 608 is true, control continues to 612. If 608 is false, control can remain at 608. At 612, valve control module 236 opens air valve 170 to a predetermined opening degree (e.g., partially or fully open), allowing air to flow from air valve 170 to a second position. At 616, valve control module 236 determines whether the engine state is set to running. If 616 is false, control can return to 608. If 616 is true, control can continue to 620.

[0099] At 620, valve control module 236 closes air valve 170. Valve control module 236 can maintain air valve 170 closed until the next engine start. In various embodiments, valve control module 236 can open air valve 170 while the engine is running, when one or more conditions are met.

[0100] Figure 7A , Figure 7B and Figure 7C These are flowcharts illustrating example multi-layer threshold control methods 700, 704, and 708 for exhaust combustors, respectively. As described above, each of methods 700, 704, and 708 can be executed during and / or before engine start. By way of example only, methods 700, 704, and 708 are executed using relevant components of the exhaust control module 138 and the exhaust system 120.

[0101] refer to Figure 7A Method 700 is configured to operate burner 154 until an upper threshold is reached, and then maintain the temperature at or near a lower threshold. At 710, method 700 optionally determines whether a cold start condition is detected. For example, method 700 determines whether the engine coolant temperature is below a threshold, whether the engine has been shut down for a predetermined period, etc. If true, then method 700 continues to 716. If false, then method 700 terminates, and the engine can start according to normal operating parameters (e.g., without operating burner 154). In some examples, method 700 can be performed regardless of whether a cold start condition is detected.

[0102] At 716, method 700 (e.g., exhaust control module 138) activates combustor 154. In some examples, method 700 may increase the engine idle speed to increase exhaust flow when combustor 154 is activated. At 720, method 700 determines whether the exhaust temperature measured downstream of DPF 126 (e.g., using sensor 178 located at the outlet of DPF 126) has reached an upper limit threshold. If true, then method 700 proceeds to 724. If false, then method 700 continues to monitor the temperature measured by sensor 178 to determine whether the measured temperature has reached the upper limit threshold.

[0103] At 724, the burner is shut off. At 728, method 700 determines whether the measured temperature has reached the lower threshold. If true, then method 700 continues to 732. If false, then method 700 continues to monitor the temperature measured by sensor 178 to determine whether the measured temperature has reached the lower threshold.

[0104] At 732, method 700 maintains the exhaust temperature at a lower threshold. For example, method 700 may activate the combustor when the measured temperature reaches or deviates from the lower threshold, and deactivate the combustor when the measured temperature reaches or deviates from the lower threshold. Method 700 may continue to selectively activate and deactivate the combustor during engine operation to maintain the exhaust temperature at the lower threshold (e.g., to compensate for sustained low-load operation).

[0105] refer to Figure 7B Method 704 is configured to shut off burner 154 until an upper threshold is reached, and turn on burner 154 when a lower threshold is reached, cycling between the upper and lower thresholds. Accordingly, method 704 is executed in a manner similar to method 700 until 728. At 728, method 704 determines whether the measured temperature has reached the lower threshold. If true, then method 704 continues to 716 to turn on burner 154. If false, then method 704 continues to monitor the temperature measured by sensor 178 to determine whether the measured temperature has reached the lower threshold.

[0106] refer to Figure 7C Method 708 is configured to operate burner 154 using different sets of upper and lower threshold values. For example, at 710, method 708 determines whether a cold start condition is detected. If true, then method 708 proceeds to 712 and selects a first set of threshold values ​​(e.g., 200°C and 300°C). If false, then method 708 proceeds to 714 and selects a second set of threshold values ​​(e.g., 200°C and 225°C). Method 708 can then be performed in a manner similar to one of methods 700 and 704.

[0107] In another example using different sets of thresholds, burner 154 may initially operate until the measured temperature reaches a first upper threshold (e.g., 300°C or higher), and then shut off until the measured temperature reaches a lower threshold. However, instead of shutting off burner 154 to maintain the measured temperature at the lower threshold or increasing the measured temperature to the first upper threshold, a second upper threshold (e.g., a second upper threshold of 225°C or 250°C) lower than the first upper threshold can be selected. For example, the exhaust temperature measured upstream of burner 154 may indicate that the exhaust temperature is sufficient to heat SCR catalyst 124 without requiring burner 154 to be additionally heated to the first upper threshold. In this case, burner 154 could instead operate only until the second upper threshold is reached, and then shut off.

[0108] The foregoing description is merely illustrative and is by no means intended to limit the scope of this disclosure, its application, or its uses. The broad teachings of this disclosure can be implemented in various forms. Therefore, while this disclosure contains specific examples, its true scope should not be so limited, as other modifications will become apparent upon examination of the accompanying drawings, specification, and the following claims. It should be understood that one or more steps in the method may be performed in a different order (or simultaneously) without altering the principles of this disclosure. Furthermore, although each embodiment in these examples is described above as having certain features, any one or more of these features described with respect to any embodiment of this disclosure may be implemented in and / or combined with features of any other embodiment, even if such combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and substitutions between one or more embodiments remain within the scope of this disclosure.

[0109] Spatial and functional relationships between components (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms including “connection,” “joint,” “link,” “proximity,” “near,” “on top of,” “above,” “below,” and “set.” Unless explicitly described as “direct,” when describing the relationship between a first component and a second component in the above disclosure, this relationship can be a direct relationship where no other intervening components exist between the first and second components, or it can be an indirect relationship between the first and second components where one or more intervening components (spatial or functional) exist. As used herein, the phrases A, B, and C at least one should be interpreted as meaning logical (A or B or C), using non-exclusive logical OR, and should not be interpreted as meaning “at least one of A, at least one of B, and at least one of C.”

[0110] In the diagram, the direction of the arrow generally indicates the flow of information (such as data or instructions) of interest. For example, when elements A and B exchange various information, but the information transmitted from element A to element B is relevant to the diagram, the arrow can point from element A to element B. This unidirectional arrow does not mean that no other information is transmitted from element B to element A. Furthermore, for information sent from element A to element B, element B can send a request for that information or receive an acknowledgment of that information to element A.

[0111] In this application, the terms "module" or "controller" are used in place of the term "circuit". The term "module" may refer to, be a part of, or include the following: Application-Specific Integrated Circuit (ASIC); Digital, Analog, or Mixed-Analog / Digital Discrete Circuit; Digital, Analog, or Mixed-Analog / Digital Integrated Circuit; Combinational Logic Circuit; Field-Programmable Gate Array (FPGA); Processor Circuit (shared, dedicated, or group) that executes code; Memory Circuit (shared, dedicated, or group) that stores code executed by the processor circuit; Other suitable hardware components that provide the described functionality; or combinations of some or all of the above, such as in a system-on-a-chip.

[0112] This module may contain one or more interface circuits. In some examples, these interface circuits may include wired or wireless interfaces that connect to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functionality of any given module in this disclosure can be distributed among multiple modules connected via interface circuits. For example, multiple modules can allow for load balancing. In another example, a server (also referred to as a remote or cloud) module may perform some functions on behalf of a client module.

[0113] The terminology used above can include software, firmware, and / or microcode, and can refer to programs, routines, functions, categories, data structures, and / or objects. The term "shared processor circuit" covers a single processor circuit that executes some or all of the code from multiple modules. The term "group processor circuit" covers a processor circuit that, in conjunction with additional processor circuitry, executes some or all of the code from one or more modules. The reference to multiple processor circuits covers multiple processor circuits on a discrete chip, multiple processor circuits on a single chip, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination thereof. The term "shared memory circuit" covers a single memory circuit that stores some or all of the code from multiple modules. The term "group memory circuit" covers a memory circuit that, in conjunction with additional memory, stores some or all of the code from one or more modules.

[0114] The term memory circuit is a subset of the term computer-readable medium. As used herein, the term computer-readable medium does not cover transient electrical or electromagnetic signals propagating through a medium (e.g., on a carrier wave); the term computer-readable medium can therefore be considered tangible and non-transient. Non-limiting examples of non-transient tangible computer-readable media include: non-volatile memory circuits (e.g., flash memory circuits, erasable programmable read-only memory circuits, or mask read-only memory circuits), volatile memory circuits (e.g., static random access memory circuits or dynamic random access memory circuits), magnetic storage media (e.g., analog or digital magnetic tape or hard disk drives), and optical storage media (e.g., CDs, DVDs, or Blu-ray discs).

[0115] The devices and methods described in this application can be implemented, in part or in whole, by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions implemented in a computer program. The aforementioned functional blocks, flowchart components, and other elements can be transferred into a computer program through the routine work of an experienced technician or programmer.

[0116] These computer programs contain processor-executable instructions stored on at least one non-volatile, tangible, computer-readable medium. These computer programs may also contain or depend on the stored data. These computer programs may encompass a basic input / output system (BIOS) that interacts with the hardware of the dedicated computer, device drivers that interact with specific devices of the dedicated computer, one or more operating systems, user applications, background services, background applications, etc.

[0117] Computer programs can contain: (i) descriptive text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Representation); (ii) assembly code; (iii) object code generated from source code by a compiler; (iv) source code executed by an interpreter; (v) source code compiled and executed by a real-time compiler, etc. As an example only, source code can be written using syntax from languages ​​including: C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, etc. Fortran, Perl, Pascal, Curl, OCaml, HTML5 (Hypertext Markup Language, 5th Revision), Ada, ASP (Dynamic Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Visual Lua, MATLAB, SIMULINK and

Claims

1. An exhaust control system for a vehicle, the exhaust control system comprising: A temperature sensor, positioned downstream of the exhaust combustor and upstream of a selective catalytic reduction catalyst in the vehicle's exhaust system, wherein the temperature sensor is configured to generate a measurement signal indicating the temperature of the exhaust gas flowing through the exhaust system at the outlet of a diesel particulate filter located downstream of the exhaust combustor; and Exhaust control module, the exhaust control module being configured to: The system detects cold start conditions and, in response to detecting said cold start conditions, activates the exhaust combustor to heat the exhaust gas, wherein activating the exhaust combustor involves burning air and fuel in the combustion chamber of the exhaust combustor. The temperature of the exhaust gas is monitored based on the measurement signal. After the exhaust burner is turned on, it is turned off based on the exhaust temperature reaching a first upper limit threshold temperature. After shutting down the exhaust burner, the decreasing exhaust temperature is continuously monitored, and the exhaust burner is turned on based on the exhaust temperature reaching a first lower threshold temperature, wherein the first lower threshold temperature is less than the first upper threshold temperature. The exhaust control module is also configured to detect a sustained low load condition after the cold start condition, and in response to detecting the sustained low load condition, operate the exhaust combustor based on a second upper threshold temperature and a second lower threshold temperature, wherein the second upper threshold temperature is less than the first upper threshold temperature.

2. The exhaust control system as described in claim 1, wherein, The temperature sensor is located at the outlet of the diesel particulate filter.

3. The exhaust control system as described in claim 1, wherein, The exhaust control module is configured to turn on the exhaust burner before the engine is started.

4. The exhaust control system as described in claim 1, wherein, The exhaust control module is configured to maintain the exhaust at the first lower threshold temperature.

5. The exhaust control system as described in claim 1, wherein, After the exhaust gas temperature reaches the first lower threshold temperature and the exhaust gas burner is turned on, the exhaust gas control module is configured to turn off the exhaust gas burner when the exhaust gas temperature reaches the first upper threshold temperature.

6. The exhaust control system as described in claim 1, wherein, The first upper limit threshold temperature is greater than or equal to 300°C.

7. The exhaust control system as described in claim 1, wherein, The exhaust control module is configured to detect cold start conditions and, in response to detecting the cold start conditions, to activate the exhaust combustor before the engine starts.

8. The exhaust control system as described in claim 1, wherein, The exhaust control module is configured to increase the engine idle speed when the exhaust burner is turned on.

9. The exhaust control system as claimed in claim 1, wherein, The exhaust control module is configured to: detect cold start conditions; and, in response to detecting the cold start conditions, operate the exhaust burner based on a first set of thresholds including the first upper threshold temperature and the first lower threshold temperature. Furthermore, in response to the absence of the cold start condition, the exhaust combustor is operated based on a second set of thresholds including the second upper threshold temperature and the second lower threshold temperature.

10. The exhaust control system of claim 1, further comprising: An air pump configured to pump air into the combustion chamber of the exhaust burner; A spark plug configured to ignite the air / fuel mixture within the combustion chamber of the exhaust combustor; A fuel control module configured to selectively actuate a fuel injector and initiate fuel injection when the vehicle's engine is off but before the engine is started. A pump control module configured to selectively activate the air pump when the engine is off and before the engine is started. as well as A spark control module configured to selectively apply power to the spark plugs and begin providing a spark when the engine is off and before the engine is started.

11. The exhaust control system of claim 1, further comprising: A diesel exhaust fluid injector configured to inject diesel exhaust fluid into the exhaust system, upstream of the selective catalytic reduction catalyst. as well as A diesel exhaust fluid control module is configured to selectively actuate the diesel exhaust fluid injector and initiate the injection of diesel exhaust fluid when the vehicle's engine is off and before the engine is started.

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