GB2596430A

GB2596430A - Systems and methods for detecting low quality reductant

Info

Publication number: GB2596430A
Application number: GB2111684.3A
Authority: GB
Inventors: Thirumalai Govindan N; Kantilal Kasture Dhanyakumar; Shivaji Suryavanshi Lalit; S Belsare Shilpa; Kumar Chembooli Shakthi; Patwardhan Sandeep
Original assignee: Cummins Emission Solutions Inc
Current assignee: Cummins Emission Solutions Inc
Priority date: 2021-08-13
Filing date: 2021-08-13
Publication date: 2021-12-29
Also published as: GB202111684D0

Abstract

A controller 170 for an aftertreatment system 100 including a selective catalytic reduction (SCR) system 160, is configured to: in response to determining that a reductant has been added to a reductant storage tank 145, determine a post-refill conversion efficiency of the SCR system; initiate a regeneration process for regenerating the SCR system; and, after the regeneration process has occurred, determine a post-regen conversion efficiency of the SCR system. The controller generates a reductant quality management (RQM) fault signal indicative of the reductant being of low quality in response to (i) the post-refill conversion efficiency being between a first threshold and a second threshold that is smaller than the first threshold, and (ii) the post-regen current conversion efficiency being between the first threshold and a third threshold that is smaller than the second threshold.

Description

SYSTEMS AND METHODS FOR DETECTING LOW QUALITY

REDUCTANT

TECHNICAL FIELD

[0001] The present disclosure relates generally to after-treatment systems for use with internal combustion (IC) engines.

BACKGROUND

[0002] Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by engines such as IC engines. Conventional exhaust gas aftertreatment systems include any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust aftertreatment systems for diesel-powered IC engines includes a SCR system which includes an SCR catalyst formulated to convert NON (NO and NO2 in some fraction) into harmless nitrogen gas (NI1) and water vapor (H2O) in the presence of ammonia (NH3).

[0003] Generally, a reductant such as a diesel exhaust fluid (e.g., an aqueous urea solution) is inserted into the aftertreatment system as a source of ammonia. The reductant facilitates the decomposition of the constituents of the exhaust gas by the SCR system. During use, the reductant may be deposited on the SCR system. Over time, the reductant deposits can build up and lead to reduction in a SCR catalytic conversion efficiency (hereinafter "CE") of the SCR system. The SCR catalyst within the SCR system is generally heated to remove reductant deposits. However, if the temperature is not high enough or the heating duration is not long enough, the reductant deposits may not be fully removed by heating. The unremoved deposits will harden over time and can become extremely hard to remove. Therefore, to remove reductant deposits and regenerate the SCR catalyst within the SCR system, the SCR catalysts are typically heated to a set temperature of greater than 500 degrees Celsius to evaporate the reductant deposits formed on the SCR catalyst within the SCR system and/or other locations of the aftertreatment system. However, exposure to such high temperatures on a regular basis can also lead to aging of the SCR catalyst within the SCR system and reduction in the SCR catalyst's operational life. Moreover, use a low quality reductant (e.g., an over diluted reductant) may also cause a reduction in CE of the SCR catalyst within the SCR system. While reductant quality sensors may be integrated into the reductant tank of an aftertreatment system for determining a quality of the reductant, such sensors can be costly, faulty, and need regular maintenance to work properly.

SUMMARY OF THE INVENTION

100041 Embodiments described herein relate generally to systems and methods for detecting low quality reductant, and more specifically to systems and methods for detecting low quality reductant without using a reductant quality sensor.

[00051 In some embodiments, a controller for an aftertreatment system including a selective catalytic reduction (SCR) system, is configured to in response to determining that a reductant has been added to a reductant storage tank of the aftertreatment system, determine a post-refill conversion efficiency of the SCR system; initiate a regeneration process for regenerating the SCR system; after the regeneration process has occurred, determine a post-regen conversion efficiency of the SCR system; and generate a reductant quality management (ROM) fault signal indicative of the reductant being of low quality in response to: (i) the post-refill conversion efficiency being between a first threshold and a second threshold that is smaller than the first threshold, and (ii) the post-regen current conversion efficiency being between the first threshold and a third threshold that is smaller than the second threshold.

100061 In some embodiments, the controller is further configured to generate a SCR fault signal in response to the new current conversion efficiency being below the third threshold.

[00071 In some embodiments, the controller is further configured to determine whether a set of screening conditions of the SCR system have been met before determining the post-refill conversion efficiency of the aftertreatment system.

100081 In some embodiments, the set of screening conditions comprise at least one of an exhaust flow rate, an ammonia to NO ratio (ANR), a SCR bed temperature, a system out NON, an engine out NON, a reductant consumption within a certain threshold, a reductant storage tank being refilled, and a difference between an exponentially weighted moving average (EWMA) filter value before and after reductant tank refill.

100091 In some embodiments, the controller is further configured to: in response to a pre-refill conversion efficiency of the aftertreatment system before the reductant is added to the reductant storage tank being below an aged SCR threshold, determine that the SCR system is aged; and initiate regeneration of the SCR system.

100191 In some embodiments, the controller is further configured to: in response to the regeneration process not having occurred after initiation of the regeneration process, generate a user signal requesting a user to initiate a stationary regeneration process.

BRIEF DESCRIPTION OF THE DRAWINGS

100111 The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several implementations in accordance with the disclosure and are therefore not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

100121 FIG. 1 is a schematic illustration of an aftertreatment system, according to an embodiment.

100131 FIG. 2 is a block diagram of a controller that may be included in the aftertreatment system of FIG. 1, according to an embodiment.

100141 FIGS. 3A and 3B are flow charts showing a method for determining a reductant quality of a reductant, according to an embodiment.

100151 FIG. 4 are plots illustrating various states and parameters and of an aftertreatment system operated with a low quality reductant that includes a 21 wt% aqueous urea solution, and generation of a fault code indicative of the reductant being of low quality using the method of FIGS. 3A-3B.

DETAILED DESCRIPTION

100161 Embodiments described herein relate generally to systems and methods for detecting low quality reductant, and more specifically to systems and methods for detecting low quality reductant without using a reductant quality sensor. Embodiments described herein are also related to systems and methods for responding to a fault condition depending on whether a reductant quality management (RQM) fault condition or a SCR fault condition is determined.

[00171 Determining whether a low CE of a SCR catalyst within a SCR system is due to low reductant quality, because of a buildup of reductant deposits on the SCR catalyst, or due to an aged SCR system (e.g., an SCR catalyst within the SCR system being irreversibly degraded) is imperative for a proper running of a vehicle's aftertreatment system. For example, if a low CE is because of a buildup of reductant deposits on the SCR system, the aftertreatment system may respond by heating up the SCR catalyst within the SCR system in order to regenerate the SCR catalyst. On the other hand, if a low CE is due to an aged SCR catalyst within the SCR system, the SCR catalyst may have to be replaced within the aftertreatment system. Therefore it is helpful to determine the cause of a low CE. Moreover, use of a low quality reductant (e.g., a reductant having less than 32.5 wt% of the reductant active material, such as urea, in an aqueous solution) can also reduce the CE of the SCR catalyst. Some aftertreatment systems may use a reductant quality sensor integrated into a reductant fluid tank to determine whether a low CE is due to low reductant quality or an aged SCR catalyst within an SCR system. Reductant quality sensors can be costly, faulty, and need regular maintenance to work properly.

100181 In contrast, various embodiments of the systems and methods described herein for determining low reductant quality may provide a variety of benefits including: (1) allowing determination of a low quality reductant being used in an aftertreatment system without using a reductant quality sensor; (2) reducing costs by allowing elimination of a reductant quality sensor from the aftertreatment system; (3) reducing maintenance costs related to a reductant quality sensor; and (4) ensuring that aftertreatment system runs smoothly by reducing reliance on faulty reductant quality sensors.

100191 FIG. 1 is a schematic illustration of an aftertreatment system 100, according to an embodiment. The aftertreatment system 100 is configured to receive exhaust gas (e.g., diesel exhaust gas from an engine 110) and treat the exhaust gas constituents (e.g., NON, CO, CO2) of the exhaust gas. The aftertreatment system 100 includes an engine 110, an oxidation catalyst 130, a filter 135, a diesel reduction tank 150 coupled to a reductant insertion assembly 140, and a reductant storage tank 145. Additionally, the after-treatment system 100 includes a SCR system 160, a hydrocarbon insertion assembly 120, and a controller 170 in addition to a variety of sensors 114a-114e, 116, and 165a-I65b which are explained in more detail below.

100201 The engine 110 may include, for example, a diesel engine, a gasoline engine, a natural gas engine, a dual fuel engine, a biodiesel engine, an E-85 engine, or any other suitable engine). In some embodiments, the engine 110 includes a diesel engine. The engine 110 combusts fuel and generates an exhaust gas that includes NON, CO, CO2, and other constituents.

[00211 The aftertreatment system 100 includes housings 101, 102, and 103 within which components of the aftertreatment system 100 are disposed. Each of the housings 101, 102, and 103 may be formed from a rigid, heat-resistant and corrosion-resistant material, for example stainless steel, iron, aluminum, metals, ceramics, or any other suitable material. Each of the housings 101, 102, and 103 may also have any suitable cross-section, for example, circular, square, rectangular, oval, elliptical, polygonal, or any other suitable shape. While shown as separate components, in some embodiments, the housings 101, I 02, 103 may be integrated into a single structure.

100221 Each of the housings 101, 102, and 103 may have inlet and outlet conduits structured receive and expel exhaust gas within the aftertreatment system 100. In some embodiments, the inlet conduit 112 is structured to receive exhaust gas from the engine 110 and communicate the exhaust gas to an internal volume defined by the housing 101. In some embodiments, conduit 125 may be coupled to both housing 101 and housing 102 may function as both an outlet conduit for housing 101 and an inlet conduit for housing 102. In some embodiments, conduit 155 may be coupled to both housing 102 and housing 103 and function as both an outlet conduit for housing 102 and an inlet conduit for housing 103. In some embodiments, outlet conduit 156 may be coupled to an outlet for the housing I 03 and structured to expel treated exhaust gas into the environment (e.g., treated to remove particulate matter such as soot by the filter 135 and/or reduce constituents of the exhaust gas such as NO gases, CO, unburnt hydrocarbons, etc. included in the exhaust gas by the SCR system 160 and the oxidation catalyst 130).

100231 A first NO sensor I 65a may be configured to measure an amount NO gases included in the exhaust gas flowing into the aftertreatment system 100 and may include a physical sensor or a virtual sensor. Triple exhaust gas temperature sensors 114a, 114b, and 114c are positioned in the inlet conduit 112 to the housing 101, downstream of the oxidation catalyst 130, and downstream of the filter 135. The triple exhaust gas temperature sensors 114a, 114b, and 114c are configured to measure the temperature of the exhaust gas passing through the diesel oxidation catalyst and the diesel particulate filter. Differential pressure sensor 116 may be positioned across the filter 135. The differential pressure sensor 116 may be configured measure exhaust gas pressure and determine when a regeneration process should begin to clear the filter 135 of particulate matter (e.g., soot, debris, inorganic particles, etc.), i.e., regenerate the filter. Dual exhaust gas temperature sensors 114d and 114e are positioned in the inlet conduit 115 and outlet conduit 156 respectively. Sensors 114d and 114e may be configured to measure the temperature of the exhaust gas entering and leaving SCR system 160.

100241 In some embodiments, sensor I 65b may be a second NO sensor configured to determine an amount of NO gases expelled into the environment after passing through the SCR system 160. In other embodiments, the sensor 165b may comprise a particulate matter sensor configured to determine an amount of particulate matter (e.g., soot included in the exhaust gas exiting the filter 135) in the exhaust gas being expelled into the environment. In still other embodiments, the sensor 165b may comprise an ammonia sensor configured to measure an amount of ammonia in the exhaust gas flowing out of the SCR system 160, i.e., determine the ammonia slip. This may be used as a measure of a catalytic conversion efficiency of the SCR system 160 for adjusting an amount of reductant to be inserted into the SCR system 160, and/or adjusting a temperature of the SCR system 160 so as to allow the SCR system 160 to effectively use the ammonia for catalytic decomposition of the NOx gases included in the exhaust gas flowing therethrough. The AMOx catalyst 175 may be positioned downstream of the SCR system 160 so as to decompose any unreacted ammonia in the exhaust gas downstream of the SCR system 160.

100251 The oxidation catalyst 130 may be positioned upstream of the SCR system 160 and configured to decompose unburnt hydrocarbons and/or CO included in the exhaust gas. in some embodiments, the oxidation catalyst 130 may include a diesel oxidation catalyst. The filter 135 is disposed downstream of the oxidation catalyst 130 and upstream of the SCR system 160 and configured to remove particulate matter (e.g., soot, debris, inorganic particles, etc.) from the exhaust gas. In various embodiments, the filter 135 may include a ceramic filter. In some embodiments, the filter 135 may include a cordierite filter which can, for example, be an asymmetric filter. In yet other embodiments, the filter 135 may be catalyzed. In some embodiments, a differential pressure sensor 116 may be disposed at across the filter 135 and configured to measure a differential pressure across the filter 135. The differential filter pressure may be indicative of a plugging of the filter 135, as described in further detail herein.

[00261 The SCR system 160 is formulated to decompose constituents of an exhaust gas flowing therethrough in the presence of a reductant, as described herein. In some embodiments, the SCR system 160 may include a selective catalytic reduction filter (SCRF). Any suitable SCR system 160 may be used such as, for example, platinum, palladium, rhodium, cerium, iron, manganese, copper, and vanadium based catalyst or any other suitable catalyst, or a combination thereof The SCR system 160 may be disposed on a suitable substrate such as, for example, a

B

ceramic (e.g., cordierite) or metallic (e.g., kanthal) monolith core which can, for example, define a honeycomb structure. A washcoat can also be used as a carrier material for the SCR system 160. Such washcoat materials may comprise, for example, aluminum oxide, titanium dioxide, silicon dioxide, any other suitable washcoat material, or a combination thereof 100271 Although FIG. I, shows only the oxidation catalyst 130, the filter 135, the SCR system 160, and the AMO, catalyst 175 disposed within the internal volume defined by the housings 101, 102, and 103 in other embodiments, a plurality of aftertreatment components may be disposed within the internal volume defined by the housings 101, 102, and 103 in addition to the oxidation catalyst 130, the filter 135, the SCR system 160 and the AMOK catalyst 175. Such aftertreatment components may comprise, for example, mixers, baffle plates, secondary filters (e.g., a secondary partial flow or catalyzed filter) or any other suitable aftertreatment component.

100281 In some embodiments, the aftertreatment system 100 may also include the hydrocarbon insertion assembly 120. The hydrocarbon insertion assembly 120 is configured to insert hydrocarbons (e.g., diesel) into the exhaust gas. The oxidation catalyst 130 catalyzes the combustion of the hydrocarbons which increases the temperature of the exhaust gas. Heating the exhaust gas may be used to regenerate the filter 135 by burning off particulate matter that may have accumulated on the filter 135, and/or regenerate the SCR system 160 by evaporating reductant deposits deposited on the SCR system 160. In some embodiments, a heater (not shown) may be coupled to the SCR system 160 and configured to heat the SCR system 160 to a regeneration temperature (e.g., based on a command from the controller 170).

[00291 A reductant port 142 may be positioned on a sidewall of the decomposition reactant tube (DRT) 150 and structured to allow insertion of a reductant therethrough into the internal volume defined by the housing 102. The reductant port 142 may be positioned upstream of the SCR system 160 (e.g., to allow reductant to be inserted into the exhaust gas upstream of the SCR system 160) or over the SCR system 160 (e.g., to allow reductant to be inserted directly on the SCR system 160). In other embodiments, the reductant port 142 may be disposed on the inlet conduit 125 and configured to insert the reductant into the inlet conduit 125 upstream of the SCR system 160. In such embodiments, mixers, baffles, vanes or other structures may be positioned in the inlet conduit 125 so as to facilitate mixing of the reductant with the exhaust gas.

[0030] The reductant storage tank 145 is structured to store a reductant. The reductant Is formulated to facilitate decomposition of the constituents of the exhaust gas (e.g., NO gases included in the exhaust gas). Any suitable reductant may be used. In some embodiments, the exhaust gas comprises a diesel exhaust gas and the reductant comprises a diesel exhaust fluid. For example, the diesel exhaust fluid may comprise urea, an aqueous solution of urea, or any other fluid that comprises ammonia, by-products, or any other diesel exhaust fluid as is known in the arts (e.g., the diesel exhaust fluid marketed under the name ADBLUEL). For example, the reductant may comprise an aqueous urea solution having a particular ratio of urea to water. In some embodiments, the reductant can comprise an aqueous urea solution including 32.5% by weight of urea and 67.5% by weight of deionized water, including 40% by weight of urea and 60% by weight of deionized water, or any other suitable ratio of urea to deionized water. An aqueous urea solution having a less than 32.5% by weight of urea may be considered a low quality reductant. A low quality reductant may cause a decrease in the CE of the SCR system 1560 because of the inability of the low quality reductant to produce sufficient ammonia needed by the SRC system 165 to treat reduce NO gases included in the exhaust gas.

100311 A reductant insertion assembly 140 is fluidly coupled to the reductant storage tank 145. The reductant insertion assembly 140 is configured to selectively insert the reductant into the SCR system 160 or upstream thereof (e.g., into the DRT 150) or a mixer (not shown) positioned upstream of the SCR system 160. The reductant insertion assembly 140 may comprise various structures to facilitate receipt of the reductant from the reductant storage tank 145 and delivery to the SCR system 160, for example, pumps, valves, screens, filters, etc. 100321 The aftertreatment system 100 may also comprise a reductant injector fluidly coupled to the reductant insertion assembly 140 and configured to insert the reductant (e.g., a combined flow of reductant and compressed air) into the SCR system 160. In various embodiments, the reductant injector may comprise a nozzle having a predetermined diameter. In various embodiments, the reductant injector may be positioned in the reductant port 142 and structured to deliver a stream or a jet of the reductant into the internal volume of the housing 102 so as to deliver the reductant to the SCR system 160.

100331 The controller 170 is operatively coupled to the reductant insertion assembly 140, the exhaust gas temperature sensors I I 4a-I I 4e, the differential pressure sensor I 16, the first and second NO sensors 165a and165b respectively, and in some embodiments, the hydrocarbon insertion assembly 120. For example, the controller 170 may be communicatively coupled to the first NO sensor I 6% and may be configured to receive a first NO sensor signal from the first NO sensor 16%, for example, to determine an amount of NO gases included in the exhaust gas entering the aftertreatment system 100. The controller 170 may also be communicatively coupled to the second NO sensor I 65b and may be configured to determine a concentration of NO gases or ammonia included in the exhaust gas being expelled into the environment.

100341 The controller 170 may be configured to determine the SCR catalytic CE of the SCR system 160 based on the inlet NO amount of NO gases entering the aftertreatment system 100, and the outlet NO amount of NO gases exiting the aftertreatment system 100. For example, the controller 170 may determine a difference between the inlet NO amount and the outlet NO amount and determine the SCR catalytic CE based on the difference.

[00351 The controller 170 may also be configured to determine an amount of ammonia slip, i.e., an amount of ammonia gas in the exhaust gas downstream of the SCR system 160 based on the second NO sensor signal (e.g., an outlet NO signal) received from the second NO sensor 165b. For example, the controller 170 may be configured to correlate the outlet NO amount measured by the second NO sensor 1656, and determine the amount of ammonia slip therefrom. The controller 170 may be configured to command the reductant insertion assembly 140 to adjust an amount of the reductant inserted into the aftertreatment system 100 based on the inlet NO amount, the SCR catalytic CE, an exhaust gas temperature at an inlet of the SCR system 160 (e.g., determined by temperature sensors that may located at various positions in the aftertreatment system 100), an exhaust gas flow rate and/or any other exhaust gas parameter.

100361 The controller 170 may be operably coupled to the engine 110, the exhaust gas temperature sensors 114a-114e, the differential pressure sensor 116, the first and second NO sensors 165a and165b respectively, the hydrocarbon insertion assembly 120, and various components of the aftertreatment system 100 using any type and any number of wired or wireless connections. For example, a wired connection may include a serial cable, a fiber optic cable, a CATS cable, or any other form of wired connection. Wireless connections may include the Internet, Wi-Fi, cellular, radio, Bluetooth, ZigBee, etc. In one embodiment, a controller area network (CAN) bus provides the exchange of signals, information, and/or data. The CAN bus includes any number of wired and wireless connections.

100371 In some embodiments, the controller 170 is configured to determine an amount of reductant deposits on the SCR system I 60. For example, the controller 170 may be configured to determine the amount of reductant deposits based on the SCR catalytic CE, and amount of reductant inserted into the aftertreatment system 100, and/or an amount of ammonia slip. The controller 170 may include equations, algorithms or lookup tables to determine the amount of reductant deposits based on the one or more parameters described herein. The controller 170 is configured to cause an increase in a SCR catalyst temperature of the SCR system 160 to a regeneration temperature, for example, equal to or greater than 500 degrees Celsius (e.g., 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, or 600 degrees Celsius, inclusive) so as to regenerate the SCR system 160. The controller 170 may be configured to cause the increase in the SCR catalyst temperature to the regeneration temperature in response to the amount of reductant deposits being greater than a reductant deposit threshold. For example, a drop in the SCR catalytic CE to below 70% may indicate that a high ammonia slip is occurring indicating decomposition of reductant deposits in the SCR system 160. In some embodiments, the controller 170 may be configured to heat the SCR system 160 to the regeneration temperature by inserting hydrocarbons into the aftertreatment system 100, as previously described herein. In some embodiments, the controller 170 may be configured to selectively activate a heater coupled to the SCR system 160 to heat the SCR system 160 to the regeneration temperature.

1190381 Expanding further, the controller 170 is configured to determine if a regeneration event has successfully occurred. For example, the regeneration event may be initially triggered by the controller 170 or a central controller (not shown) of the aftertreatment system 100 or engine 110 before determining that the regeneration event was successful. The controller 170 may be configured to initiate the regeneration event in response to a SCR system CE being below a certain threshold or a predetermined time (e.g., 50 hours to 150 hours, inclusive) having passed since a previous regeneration event that may indicate that the SCR system 160 should be regenerated.

100391 The controller 170 may initiate the regeneration event by causing the hydrocarbon insertion assembly 120 to insert hydrocarbons into the exhaust gas and/or cause a heater (not shown) fluidly coupled to the aftertreatment system 100 to heat the SCR system 160. The controller 170 may determine that the regeneration event was successful in response to the catalytic conversion efficiency of the SCR system 160 being above a certain threshold. In some embodiments, the controller 170 may determine that the regeneration event was successful in removing reductant deposits by determining whether the SCR system 160 and/or the exhaust gas reached a sufficiently high temperature (e.g., 500 degrees Celsius or higher). If the regeneration event was not successful, the controller 170 may wait for another regeneration event to occur and/or generate a fault signal. In some embodiments, the controller 170 may prompt a user to perform stationary regeneration in response to the regeneration event being unsuccessful. In some embodiments, the controller 170 may monitor an SCR system CE during and/or after the regeneration event.

100401 The controller 170 is configured to determine whether a reductant added to a reductant storage tank of the aftertreatment system 100 is low quality (e.g., having a urea of less than 32.5 wt%). The controller 170 may be configured to initiate the determination of the reductant quality after a new reductant is added to the reductant storage tank and certain screening conditions of the aftertreatment system 100 have been met. In some embodiments, the screening conditions may include but are not limited to: (1) ensuring that the reductant consumption is within a certain threshold range (e.g., between 0.04 to 2 L), (2) ensuring that the reductant storage tank 145 is filled, (3) ensuring that the difference between an exponentially weighted moving average (EWMA) filter value before and after a reductant storage tank refill is above a certain threshold (e.g., above 5%), and (4) ensuring that at least one of an exhaust flow rate, an ammonia to NO ratio (ANR), a SCR bed temperature, a system out NON, an engine out NON, and a reductant consumption are within a certain threshold range.

100411 Once all the screening conditions have been met, the controller 170 may determine if a pre-refill CE of the SCR system 165, was below an aged SCR threshold. A pre-refill CE is defined as the CE measurement taken before refilling the reductant storage tank. As mentioned above, the controller 170 may be configured to determine the CE of the SCR system 160 based on the inlet amount of NO gases entering the aftertreatment system 100, and the outlet NO amount of NO gases exiting the aftertreatment system 100. For example, the controller 170 may determine a difference between the inlet amount of NO gases and the outlet amount of NO gases amount and determine the CE based on the difference. If the pre-refill CE is measured to be below the aged SCR threshold (e.g., less than 40%, the controller 170 may determine that the SCR system 165 is aged and proceed to execute the regeneration process.

100421 If the pre-refill CE is greater than the aged SCR threshold, then the controller 170 determines if a post-refill CE of the SCR system 165 after addition of the reductant is between a first threshold and a second threshold, the second threshold being lower than the first threshold. If the post-refill CE is between the first and second thresholds, then the controller 170 determines that there may be a reductant quality management (RQM) fault condition due to low reductant quality because of a buildup of reductant deposits pending confirmation after executing the regeneration process. The controller 170 is configured to set an ammonia to NO ratio to 1, and trigger a regeneration of the SCR system 165. Once the controller 170 determines that the regeneration has been completed, the controller 170 determines a post-regen CE of the SCR system 165. In response to the post-regen CE still being between the first threshold and a third threshold, which is smaller than the second threshold but larger than or equal to the aged SCR threshold, the controller 170 determines that the reductant is of low quality and generates the RQM fault condition signal. On other hand, if the post-regen CE of the SCR system 165 is determined to be below the third threshold, the controller 170 generates a SCR fault signal indicating that the SCR system 165 has failed, i.e., has irreversibly aged. Moreover, if the controller 170 determines that post-regen CE is greater than the first threshold, the controller 170 determines that the reductant is of acceptable quality and the SCR system 165 is not aged.

100431 The controller 170 may also determine whether a regeneration process initiated by the controller 170, had occurred. If the regeneration process did not occur, then the controller 170 may trigger a regeneration fault condition. The regeneration fault condition will generate a regeneration fault code that prompts a user to perform a stationary regeneration process, which encompasses a user manually generating the regeneration process. After performing stationary regeneration, the controller 170 again determines if the regeneration process was successful. If the regeneration process was successful then the controller proceeds to measure the post-regen CE after the regeneration process.

100441 To determine the post-regen CE in response to determining that the regeneration event was successful, the controller 170 may be configured to interpret an input and output NO amount in the exhaust gas received from NO sensors 165a and 165b respectively to determine an SCR system CE within a predetermined time period after the regeneration event has occurred (e.g., in a range of 30 minutes to 2 hours, inclusive after the regeneration event has occurred). The various thresholds described herein may include fixed values or ranges. For example, the first threshold may be in a range of 88%-92%, the second threshold may be in a range of 8082%, the third threshold may be in range of 48%-50%, and the aged SCR threshold may be in a range of 36%-40%.

100451 The controller 170 generates a fault signal indicative of either a low reductant quality or an aged SCR system. In some embodiments, the controller may generate a fault code stored in the memory 174 or an onboard memory of an engine control module, and/or generates an audio and/or visual alarm such as by activating a malfunction indicator lamp or a check engine light. In some embodiments, the controller 170 may also generate an engine derate signal configured to derate the engine 110 (e.g., cause power provide by the engine 110 to be reduced or a vehicle speed of a vehicle associated with the engine 110 to be reduced) in response to determining either a low reductant quality or an aged SCR system. This may prevent further damage to the SCR system 160.

100461 In some embodiments, the controller 170 includes various circuitries or modules configured to perform the operations of the controller 170 described herein. For example, FIG. 2 shows a block diagram of the controller 170, according to an embodiment. The controller 170 may include a processor 172, a memory 174, or any other computer readable medium, and a communication interface 176. Furthermore, the controller 170 includes a reductant deposit determination module I 74a, a regeneration control module I 74b, a reductant quality determination module 174c, and a fault determination module 174d. It should be understood that FIG. 2 shows only one embodiment of the controller 170 and any other controller capable of performing the operations described herein can be used.

100471 The processor 172 can comprise a microprocessor, programmable logic controller (PLC) chip, an ASIC chip, or any other suitable processor. The processor 172 is in communication with the memory 174 and configured to execute instructions, algorithms, commands, or otherwise programs stored in the memory 174.

[00481 The memory 174 comprises any of the memory and/or storage components discussed herein. For example, memory 174 may comprise a RAM and/or cache of processor 172. The memory 174 may also comprise one or more storage devices (e.g., hard drives, flash drives, computer readable media, etc.) either local or remote to controller 170. The memory 174 is configured to store look up tables, algorithms, or instructions.

[00491 In one configuration, the reductant deposit determination module I 74a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d are embodied as machine or computer-readable media (e.g., stored in the memory 174) that is executable by a processor, such as the processor 172. As described herein and amongst other uses, the machine-readable media (e.g., the memory 174) facilitates performance of certain operations of the reductant deposit determination module 174a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d to enable reception and transmission of data. For example, the machine-readable media may provide an instruction (e.g., command, etc.) to, e.g., acquire data. In this regard, the machine-readable media may include programmable logic that defines the frequency of acquisition of the data (or, transmission of the data). Thus, the computer readable media may include code, which may be written in any programming language including, but not limited to, Java or the like and any conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program code may be executed on one processor or multiple remote processors. In the latter scenario, the remote processors may be connected to each other through any type of network (e.g., CAN bus, etc.).

100501 In another configuration the reductant deposit determination module I 74a, the regeneration control module I 74b, the reductant quality determination module I 74c, and the fault determination module 174d are embodied as hardware units, such as electronic control units. As such, the reductant deposit determination module 174a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d may be embodied as one or more circuitry components including, but not limited to, processing circuitry, network interfaces, peripheral devices, input devices, output devices, sensors, etc. 100511 In some embodiments, the reductant deposit determination module 174a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d may take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (IC), discrete circuits, system on a chip (SOCs) circuits, microcontrollers, etc.), telecommunication circuits, hybrid circuits, and any other type of "circuit." In this regard, the reductant deposit determination module I 74a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d may include any type of component for accomplishing or facilitating achievement of the operations described herein. For example, a circuit as described herein may include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, registers, capacitors, inductors, diodes, wiring, and so on.

100521 Thus, the reductant deposit determination module 174a, the regeneration control module I 74b, the reductant quality determination module I 74c, and the fault determination module 174d may also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. In this regard, the reductant deposit determination module 1 74a, the regeneration control module I 74b, the reductant quality determination module I 74c, and the fault determination module I74d may include one or more memory devices for storing instructions that are executable by the processor(s) of the reductant deposit determination module I74a, the regeneration control module I 74b, the reductant quality determination module I 74c, and the fault determination module I 74d. The one or more memory devices and processor(s) may have the same definition as provided below with respect to the memory 174 and the processor 172.

[0053] In the example shown, the controller 170 includes the processor 172 and the memory 174. The processor 172 and the memory 174 may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect to the reductant deposit determination module 174a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d. Thus, the depicted configuration represents the aforementioned arrangement in which the reductant deposit determination module 174a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d are embodied as machine or computer-readable media. However, as mentioned above, this illustration is not meant to be limiting as the present disclosure contemplates other embodiments such as the aforementioned embodiment where the reductant deposit determination module I 74a, the regeneration control module I 74b, the reductant quality determination module 174c, and the fault determination module 174d or at least one module of the reductant deposit determination module 174a, the regeneration control module 174b, the reductant quality determination module 174c, and the fault determination module 174d are configured as a hardware unit All such combinations and variations are intended to fall within the scope of the present disclosure.

[0054] The processor 172 may be implemented as one or more general-purpose processors, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital signal processor (DSP), a group of processing components, or other suitable electronic processing components. In some embodiments, the one or more processors may be shared by multiple circuits (e.g., the reductant deposit determination module 174a, the regeneration control module I 74b, the reductant quality determination module I 74c, and the fault determination module I 74d) may comprise or otherwise share the same processor which, in some example embodiments, may execute instructions stored, or otherwise accessed, via different areas of memory). Alternatively or additionally, the one or more processors may be structured to perform or otherwise execute certain operations independent of one or more coprocessors. In other example embodiments, two or more processors may be coupled via a bus to enable independent, parallel, pipelined, or multi-threaded instruction execution. All such variations are intended to fall within the scope of the present disclosure. The memory 174 (e.g., RAM, ROM, Flash Memory, hard disk storage, etc.) may store data and/or computer code for facilitating the various processes described herein. The memory 174 may be communicably connected to the processor 172 to provide computer code or instructions to the processor 172 for executing at least some of the processes described herein. Moreover, the memory 174 may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory 174 may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described herein.

100551 The communication interface 176 may include wireless interfaces (e.g., jacks, antennas, transmitters, receivers, communication interfaces, wire terminals, etc.) for conducting data communications with various systems, devices, or networks. For example, the communication interface 176 may include an Ethernet card and port for sending and receiving data via an Ethernet-based communications network and/or a Wi-Fi communication interface for communicating with the first NO sensor 165a, the second NO sensor 165b, the differential pressure sensor 116, the temperature sensors 114a-114e, the reductant insertion assembly 140, and/or the hydrocarbon insertion assembly 120. The communication interface 176 may be structured to communicate via local area networks or wide area networks (e.g., the Internet, etc.) and may use a variety of communications protocols (e.g., IP, LON, Bluetooth, ZigBee, radio, cellular, near field communication, etc.).

10050 The reductant deposit determination module 174a is configured to determine the amount of reductant deposited on the SCR system 160. For example, the reductant deposit determination module 174a may receive an inlet NO signal from the first NO sensor 16% that corresponds to an inlet NO amount, receive an outlet NO signal from the second NO sensor 165b that corresponds to the outlet NO amount, a reductant insertion signal indicative of an amount of reductant inserted into the aftertreatment system 100, and determines the amount of reductant deposited on the SCR system 160, as previously described herein.

100571 The regeneration control module 174b is configured to control regeneration of the SCR system 160. For example, the regeneration control module 174b is configured to generate a SCR heating signal configured to activate the hydrocarbon insertion assembly 120 or the heater 142 to cause heating of the SCR system 160 to the regeneration temperature for the time period. In other embodiments, the regeneration control module 174b may be configured to cause the hydrocarbon insertion assembly 120 to insert hydrocarbons into the exhaust gas so as to increase the temperature of the exhaust gas for regenerating the SCR system 160.

[00581 The reductant quality determination module 174c is configured to determine a reductant quality based on the SCR system CE. Additionally, the reductant quality determination module 174c is configured to determine whether a low SCR system CE is due to low reductant quality or an aged SCR system. The fault determination module I74d is configured to generate a fault signal in response to the determination made by the reductant quality determination module 174c that a low SCR system CE due to either a low reductant quality or an aged SCR system 160. The fault signal is indicative of either a low reductant quality or an aged SCR system.

[0059] FIGS. 3A and 3B are flow charts showing an example reductant quality monitoring method 200 for detecting low quality reductant without a reductant quality sensor and responding to a fault condition depending on whether the controller 170 determines a reductant quality management (ROM) fault condition or an SCR fault condition. While described with reference to the controller 170 and the SCR system 160 of the aftertreatment system 100, the operations of the process 200 can be used with any controller included in any aftertreatment system. In some embodiments, the method for monitoring reductant quality may primarily determine reductant quality by determining whether a CE falls within certain thresholds, as described herein.

100601 The method 200 may be initiated in response to new reductant being added to a reductant storage tank of the aftertreatment system 100. For example, before the process 200 begins, the controller 170 may ensure that all screening conditions of the aftertreatment system 100 have been met. In some embodiments, these screening conditions may include but are not limited to: (1) ensuring that the reductant consumption is between a certain threshold (e.g., between 0.04 to 2 L), (2) ensuring that the reductant storage tank 145 is filled, (3) ensuring that the difference between an exponentially weighted moving average (EWMA) filter value before and after a reductant storage tank refill is between a certain threshold (e.g., greater than 5%), and (4) ensuring that at least one of an exhaust flow rate, an ammonia to NO ratio (ANR), a SCR bed temperature, a system out NON, an engine out NON, and a reductant consumption are within a certain threshold.

[00611 Once all the screening conditions have been met, the process 200 begins at 202 by determining if a pre-refill CE of the SCR system 165 was below an aged SCR threshold. A pre-refill CE is defined as the CE measurement taken before refilling the reductant storage tank. As mentioned above, the controller 170 may be configured to determine the CE of the SCR system 160 based on the inlet amount of NO gases entering the aftertreatment system 100, and the outlet NO amount of NO gases exiting the aftertreatment system 100. For example, the controller 170 may determine a difference between the inlet NO amount and the outlet NO amount and determine the CE based on the difference. If the pre-refill CE is measured to below the aged SCR threshold (202: YES), the controller 170 may determine that the low pre-refill CE is due to an aged SCR system at 204 and proceed to execute the regeneration process at 220. The aged SCR threshold may be a fixed value (e.g., 38%) or a range (e.g., 36%-40%).

[00621 If the pre-refill CE is greater than the aged SCR threshold (202:NO), then the controller 170 determines if the post-refill CE of the SCR system 165 (e.g., the CE after reductant has been added to the reductant storage tank) is between the first threshold (e.g., 89% or between 88%-90%) and the second threshold (e.g., 82% or between 80%-82%) at 208. If the post-refill CE is between the first and second thresholds (208:YES), then the controller 170 determines that there is reductant quality management (RQM) fault condition due to low reductant quality because of a buildup of reductant deposits pending confirmation after executing the regeneration process at 220. If the post-refill CE is however below the second threshold (210: YES), then the controller 170 determines that there is a SCR fault condition due to an aged SCR system pending confirmation after beginning of the regeneration process 220. On the other hand, if the post-refill CE is above the first threshold (206: YES), then the controller 170 determines that the aftertreatment system is working properly and no fault condition is issued and the process 200 ends.

100631 At 218, either the SCR or the ROM fault conditions are pending before confirmation after the regeneration process that executes at 220. As mentioned above, if a post-refill CE is below the first threshold, then the controller 170 may execute a regeneration process to clear either the filter 135 and/or the SCR system 160 of particulate matter (e.g., soot, debris, inorganic particles, etc.). Therefore, at operation 220, the controller 170 executes the regeneration process with the ANR set to 1. At 224, the controller 170 determines if the regeneration process was successful. If the regeneration process was not successful (224: NO) then the controller 170 may trigger a regeneration fault condition at operation 226. The regeneration fault condition generates a regeneration fault code that prompts a user to perform a stationary regeneration process at 228. After performing stationary regeneration at operation 228, the controller 170 again determines if the regeneration process was successful at operation 224. If the regeneration process was successful (224: YES) then the process 200 continues to operation 230.

100641 At operation 230, the controller 170 determines if a new CE of the SCR system 165 after regenerating the SCR system 165 is between the first threshold and a third threshold (e.g., 50%, between 48%-50%, or between 36%-40%). If the post-refill CE is below the low threshold (230: NO), then the SCR fault condition is confirmed at operation 234. In response to the SCR fault condition being confirmed at operation 234, the controller 170 follows the SCR fault condition trouble shooting tree. If the post-refill CE is between the first threshold and the third threshold (232: NO and 230:YES), then the RQM fault condition is confirmed. In response to the RQM fault condition being confirmed at operation 236, the controller 170 follows the RQM fault condition trouble shooting tree. If the post-refill CE is above the first threshold (232: YES), then the controller 170 determines that there is no fault condition at operation 238 and the process 200 ends at 244.

00651 Referring now to FIG. 4, a plot is configured to display test data from a test case of using the reductant quality monitoring method of FIGS. 3A and 3B is shown. The test data demonstrates how the aftertreatment system may behave over a period of time as it is going through the reductant quality monitoring process 200. The test diagram 400 includes a regeneration state diagram 415 which is configured to demonstrate whether the SCR catalyst within the SCR system 160 is being regenerated (y-axis) as function of time (x-axis) as the aftertreatment system 100 goes through the process 200. The test diagram 400 includes an aftertreatment system (ATS) temperature diagram 420 that displays the temperature of the aftertreatment system (y-axis) as a function of time (x-axis) as the aftertreatment system goes through the process 200. The test diagram 400 includes a NO sample diagram 425 which displays the amount of NO samples (y-axis) taken by the controller 170 as a function of time (x-axis) as the aftertreatment system goes through the process 200. The test diagram 400 includes a FC status diagram 430 that is configured to display if and when a fault code has been triggered (y-axis) as function of time (x-axis) as the aftertreatment system 100 goes through the process 200. The test diagram 400 includes a pre-EWIVLA. CE diagram 435 that is configured to display the CE (y-axis) before set to a certain point(e.g., 88%) as a function of time (x-axis) as the aftertreatment system goes through the process 200. The test diagram 400 includes a EWMA CE diagram 435 that is configured to display the CE (y-axis) after the EWMA has been set to 0.88 as a function of time (x-axis) as the aftertreatment system goes through the process 200.

100661 Before data collection begins (x = 0 on x-axis), a reductant is inserted into the aftertreatment system 100. After the reductant is inserted into the aftertreatment system 100, then the controller checks to ensure that all screening conditions has been met (at approximately x-axis = 0 through x-axis = 7.504e+06), as previously described herein. Once the screening conditions have been met, the controller sets the EWMA to 0.88, sets the ANR to 0.22, and triggers regeneration at 405. Through the regeneration process, the incoming ATS temperature 450 stays relatively stable but the outgoing ATS temperature rises through the regeneration process. This is because the SCR catalyst within the SCR system may be regenerated through a heating process. After the regeneration process, the controller may run through the remaining part of the reductant quality monitoring method and determine that an RQM fault code has been triggered at 415 because the EWMA CE fell below a lower threshold (e.g., 88%) at 420.

[00671 It should be noted that the term 'example" as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

[00681 As used herein, the terms "about" and "approximately" generally mean plus or minus 10% of the stated value. For example, about 0.5 would include 0.45 and 0.55, about 10 would include 9 to 11, about 1000 would include 900 to 1100.

100691 The term "coupled" and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

100701 It is important to note that the construction and arrangement of the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements; values of parameters, mounting arrangements; use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Additionally, it should be understood that features from one embodiment disclosed herein may be combined with features of other embodiments disclosed herein as one of ordinary skill in the art would understand. Other substitutions, modifications, changes, and omissions may also be made in the design, operating conditions, and arrangement of the various exemplary embodiments without departing from the scope of the present embodiments.

100711 While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any embodiments or of what may be claimed, but rather as descriptions of features specific to particular implementations of particular embodiments. Certain features described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Claims

WHAT IS CLAIMED IS: 1. A controller for an aftertreatment system including a selective catalytic reduction (SCR) system, the controller configured to: in response to determining that a reductant has been added to a reductant storage tank of the aftertreatment system, determine a post-refill conversion efficiency of the SCR system; initiate a regeneration process for regenerating the SCR system, after the regeneration process has occurred, determine a post-regen conversion efficiency of the SCR system; and generate a reductant quality management (RQM) fault signal indicative of the reductant being of low quality in response to: (i) the post-refill conversion efficiency being between a first threshold and a second threshold that is smaller than the first threshold, and (ii) the post-regen current conversion efficiency being between the first threshold and a third threshold that is smaller than the second threshold.
2. The controller of claim 1, further configured to: generate a SCR fault signal in response to the post-regen current conversion efficiency being below the third threshold.
3. The controller of claim 1 or 2, wherein the controller is further configured to: determine whether a set of screening conditions of the SCR system have been met before determining the post-refill conversion efficiency of the aftertreatment system.
4. The controller of claim 3, wherein the set of screening conditions comprise at least one of an exhaust flow rate, an ammonia to NO ratio (ANR), a SCR bed temperature, a system out NON, an engine out NON, a reductant consumption within a certain threshold, a reductant storage tank being refilled, and a difference between an exponentially weighted moving average (EWMA) filter value before and after reductant tank refill.
The controller of claim 1, 2, 3 or 4, further configured to: in response to a pre-refill conversion efficiency of the aftertreatment system before the reductant is added to the reductant storage tank being below an aged SCR threshold, determine that the SCR system is aged: and initiate regeneration of the SCR system.
6. The controller of any preceding claim, further configured to: in response to the regeneration process not having occurred after initiation of the regeneration process, generate a user signal requesting a user to initiate a stationary regeneration process.