WO2016182895A1

WO2016182895A1 - Selective supplying of air from an air supply to reduce air consumption

Info

Publication number: WO2016182895A1
Application number: PCT/US2016/031169
Authority: WO
Inventors: Sarang S. SONAWANE
Original assignee: Cummins Emission Solutions, Inc.
Priority date: 2015-05-11
Filing date: 2016-05-06
Publication date: 2016-11-17
Also published as: CN107532492B; CN107532492A

Abstract

Systems for reducing air consumption for aftertreatment systems by selectively supplying air from an air supply may selectively control a valve to enable or disable air supplied to a dosing module. A system may include an air supply, a dosing module, a valve, and a controller. The dosing module may be in selective fluid communication with the air supply. The valve may be configured to selectively supply air from the air supply to the dosing module. The controller may be configured to interpret a parameter indicative of a temperature of a component of an exhaust system and selectively operate the valve responsive to the interpreted parameter indicative of the temperature and a predetermined threshold value.

Description

SELECTIVE SUPPLYING OF AIR FROM AN AIR SUPPLY TO REDUCE AIR CONSUMPTION

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to United States Provisional Patent Application No. 62/159,684, filed May 11, 2015, the contents of which are incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present application relates generally to the field of aftertreatment systems for internal combustion engines.

BACKGROUND

[0003] For internal combustion engines, such as diesel engines, nitrogen oxide (NO_x) compounds may be emitted in the exhaust. To reduce NO_x emissions, a SCR process may be implemented to convert the NO_x compounds into more neutral compounds, such as diatomic nitrogen, water, or carbon dioxide, with the aid of a catalyst and a reductant. The catalyst may be included in a catalyst chamber of an exhaust system, such as that of a vehicle or power generation unit. A reductant such as anhydrous ammonia, aqueous ammonia, or urea is typically introduced into the exhaust gas flow prior to the catalyst chamber. To introduce the reductant into the exhaust gas flow for the SCR process, an SCR system may dose or otherwise introduce the reductant through a dosing module that vaporizes or sprays the reductant into an exhaust pipe of the exhaust system up-stream of the catalyst chamber. Such dosing modules may be air-assisted dosing modules that utilize pressurized air to assist in injecting and atomizing or vaporizing liquid reductant. The SCR system may include one or more sensors to monitor conditions within the exhaust system.

SUMMARY

[0004] Implementations described herein relate to systems and methods for reducing air consumption for aftertreatment systems by selectively supplying air from an air supply. [0005] In one implementation, a system includes an air supply, a dosing module, a valve, and a controller. The dosing module is in selective fluid communication with the air supply. The valve is configured to selectively supply air from the air supply to the dosing module by selectively opening or closing the valve. The controller is configured to interpret a parameter indicative of a temperature of a component of an exhaust system and selectively operate the valve to enable or disable the air supply to the dosing module responsive to the interpreted parameter indicative of the temperature and a predetermined threshold value.

[0006] The controller may be configured to selectively operate the valve responsive to the interpreted parameter and a predetermined threshold value to prime the dosing module. The controller may be configured to selectively operate the valve responsive to the interpreted parameter and a predetermined threshold value to shut off a supply of air to the dosing module during operation of an engine. The controller may be further configured to interpret a parameter indicative of a status of a prior purge and selectively operate the valve responsive to the interpreted parameter indicative of the status. The controller may be configured to selectively operate the valve responsive to the interpreted parameter indicative of the status to shut off a supply of air to the dosing module for a predetermined period of time. The controller may be configured to determine a successful prior purge was completed and disable the air supply for a predetermined period of time responsive to determining the successful prior purge was completed. In some implementations, the predetermined period of time is between 0 and 30 seconds. In some implementations, determining a successful prior purge was completed is responsive to a key-on event. In some implementations, the controller is further configured to determine a temperature of an inlet of a catalyst is equal to or greater than a threshold temperature and enable air from the air supply to be provided to the dosing module responsive to determining the temperature of the inlet of the catalyst is equal to or greater than the threshold temperature. In some implementations, the predetermined threshold value is 180 °C.

[0007] Another implementation relates to a method for reducing air consumption for a dosing system. The method includes dosing reductant into an exhaust system via a dosing module in selective fluid communication with an air supply. The method also includes interpreting a first parameter indicative of a first temperature of a component of the exhaust system. The method further includes disabling air to the dosing module from the air supply via a valve responsive to the interpreted first parameter indicative of the first temperature being below a first predetermined threshold value.

[0008] In some implementations, the method further includes interpreting a second parameter indicative of a second temperature of the component of the exhaust system, and enabling air to the dosing module from the air supply via the valve responsive to the interpreted second parameter indicative of the second temperature being above a second predetermined threshold value. In some implementations, the second predetermined threshold value is less than the first predetermined threshold value. In some

implementations, the method includes interpreting a parameter value that is indicative of a status of a prior purge and priming the dosing module responsive to the interpreted parameter indicating a successful prior purge. In some implementations, interpreting the parameter value that is indicative of the status of the prior purge is responsive to a key-on event. In some implementations, disabling air to the dosing module from the air supply via the valve is for a predetermined period of time. In some implementations, the method also includes determining a temperature of an inlet of a catalyst is equal to or greater than a threshold temperature, and enabling air from the air supply to be provided to the dosing module responsive to determining the temperature of the inlet of the catalyst is equal to or greater than the threshold temperature.

[0009] Yet another implementation relates to a system that includes a temperature sensor, a dosing module, a valve, and a controller. The dosing module is in selective fluid communication with an air supply. The valve is configured to selectively supply air from the air supply to the dosing module by selectively opening or closing the valve. The controller is configured to dose reductant into an exhaust system via the dosing module in selective fluid communication with the air supply, interpret a first parameter indicative of a first temperature of a component of an exhaust system, disable air from the air supply to the dosing module for a period of time responsive to the interpreted first parameter indicative of the first temperature being below a first predetermined threshold value, interpret, after the period of time, a second parameter indicative of a second temperature of the component of the exhaust system measured by the temperature sensor, and enable air from the air supply to the dosing module responsive to the interpreted second parameter indicative of the second temperature being above a second predetermined threshold value. [0010] In some implementations, the second predetermined threshold value is less than the first predetermined threshold value. In some implementations, the predetermined period of time is between 0 and 30 seconds.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the disclosure will become apparent from the description, the drawings, and the claims, in which:

[0012] Figure 1 is a block schematic diagram of an example selective catalytic reduction system having an example reductant delivery system for an exhaust system;

[0013] Figure 2 is a process diagram for an example process for reducing air consumption for aftertreatment systems by selectively supplying air from an air supply; and

[0014] Figure 3 is a graphical diagram depicting values indicative of temperatures at a catalyst inlet and a threshold value.

[0015] It will be recognized that some or all of the figures are schematic representations for purposes of illustration. The figures are provided for the purpose of illustrating one or more implementations with the explicit understanding that they will not be used to limit the scope or the meaning of the claims.

DETAILED DESCRIPTION

[0016] Following below are more detailed descriptions of various concepts related to, and implementations of, methods, apparatuses, and systems for reducing air consumption for aftertreatment systems by selectively supplying air from an air supply. The various concepts introduced above and discussed in greater detail below may be implemented in any of numerous ways, as the described concepts are not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.

I. Overview

[0017] In some vehicles, an air-assisted dosing module may be utilized for injecting reductant into the exhaust system. The air-assisted dosing module uses pressurized air to assist in injecting and atomizing or vaporizing liquid reductant when injected into the exhaust system. In some systems, the pressurized air is always active while the vehicle is operational. Thus, in some instances, pressurized air may be emitted out of the air-assisted dosing module even when no dosing is occurring and/or when dosing would be ineffective or less effective. Accordingly, selectively supplying air from the air supply (e.g., by operating a valve positioned between an air supply conduit of the air-assisted dosing module) may reduce the amount of air consumed by the system. Such a reduction may reduce the volume needed for an air supply storage device, allow for the use of a low rated or lower capacity air compressor, reduce the operational time for an air compressor, improve fuel efficiency (by reducing the operational time for the air compressor), and/or provide other advantages to the vehicle by reducing inefficiencies.

II. Overview of Aftertreatment System

[0018] Figure 1 depicts an aftertreatment system 100 having an example reductant delivery system 110 for an exhaust system 190. The aftertreatment system 100 includes a diesel particulate filter (DPF) 102, the reductant delivery system 110, a decomposition chamber or reactor 104, a SCR catalyst 106, and a sensor 150.

[0019] The DPF 102 is configured to remove particulate matter, such as soot, from exhaust gas flowing in the exhaust system 190. The DPF 102 includes an inlet, where the exhaust gas is received, and an outlet, where the exhaust gas exits after having particulate matter substantially filtered from the exhaust gas and/or converting the particulate matter into carbon dioxide.

[0020] The decomposition chamber 104 is configured to convert a reductant, such as urea, aqueous ammonia, or diesel exhaust fluid (DEF), into ammonia. The decomposition chamber 104 includes a reductant delivery system 110 having a dosing module 112 configured to dose the reductant into the decomposition chamber 104. In some

implementations, the reductant is injected upstream of the SCR catalyst 106. The reductant droplets then undergo the processes of evaporation, thermolysis, and hydrolysis to form gaseous ammonia within the exhaust system 190. The decomposition chamber 104 includes an inlet in fluid communication with the DPF 102 to receive the exhaust gas containing NO_x emissions and an outlet for the exhaust gas, NO_x emissions, ammonia, and/or remaining reductant to flow to the SCR catalyst 106.

[0021] The decomposition chamber 104 includes the dosing module 112 mounted to the decomposition chamber 104 such that the dosing module 112 may dose the reductant into the exhaust gases flowing in the exhaust system 190. The dosing module 112 may include an insulator 114 interposed between a portion of the dosing module 112 and the portion of the decomposition chamber 104 to which the dosing module 112 is mounted. The dosing module 112 may be an Ecofit dosing module that is air-assisted for creating a homogeneous mixture of reductant and air to be injected into an exhaust flow stream. The dosing module 112 is fluidly coupled to one or more reductant sources 116 and one or more air supply sources 130.

[0022] The one or more air supply sources 130 may include an air compressor (not shown) to provide and pressurize air within the one or more air supply sources 130. A valve 132 may be in fluid communication with the one or more air supply sources 130 and the dosing module 112 to selectively supply air from the one or more air supply sources to the dosing module 112.

[0023] The dosing module 112 and valve 132 are also electrically or communicatively coupled to a controller 120. The controller 120 is configured to control the dosing module 112 to dose reductant into the decomposition chamber 104. The controller 120 may also be configured to control the valve 132. The controller 120 may include a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), etc., or combinations thereof. The controller 120 may include memory which may include, but is not limited to, electronic, optical, magnetic, or any other storage or transmission device capable of providing a processor, ASIC, FPGA, etc. with program instructions. The memory may include a memory chip, Electrically Erasable Programmable Read-Only Memory (EEPROM), erasable programmable read only memory (EPROM), flash memory, or any other suitable memory from which the controller 120 can read instructions. The instructions may include code from any suitable programming language.

[0024] In certain implementations, the controller 120 is structured to perform certain operations, such as those described herein in relation to Figure 2. In certain

implementations, the controller 120 forms a portion of a processing subsystem including one or more computing devices having memory, processing, and communication hardware. The controller 120 may be a single device or a distributed device, and the functions of the controller 120 may be performed by hardware and/or as computer instructions on a non- transient computer readable storage medium. [0025] In certain implementations, the controller 120 includes one or more modules structured to functionally execute the operations of the controller 120. In certain

implementations, the controller 120 may include air supply control module for performing the operations described in reference to Figure 2. The description herein including modules emphasizes the structural independence of the aspects of the controller 120 and illustrates one grouping of operations and responsibilities of the controller 120. Other groupings that execute similar overall operations are understood within the scope of the present application. Modules may be implemented in hardware and/or as computer instructions on a non-transient computer readable storage medium, and modules may be distributed across various hardware or computer based components. More specific descriptions of certain embodiments of controller operations are included in the section referencing Figure 2.

[0026] Example and non-limiting module implementation elements include sensors providing any value determined herein, sensors providing any value that is a precursor to a value determined herein, datalink and/or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wiring, coaxial wiring, shielded wiring, transmitters, receivers, and/or transceivers, logic circuits, hard-wired logic circuits, reconfigurable logic circuits in a particular non-transient state configured according to the module specification, any actuator including at least an electrical, hydraulic, or pneumatic actuator, a solenoid, an op-amp, analog control elements (springs, filters, integrators, adders, dividers, gain elements), and/or digital control elements.

[0027] The SCR catalyst 106 is configured to assist in the reduction of NO_x emissions by accelerating a NO_x reduction process between the ammonia and the NO_x of the exhaust gas into diatomic nitrogen, water, and/or carbon dioxide. The SCR catalyst 106 includes inlet in fluid communication with the decomposition chamber 104 from which exhaust gas and reductant is received and an outlet in fluid communication with an end of the exhaust system 190.

[0028] The exhaust system 190 may further include a diesel oxidation catalyst (DOC) in fluid communication with the exhaust system 190 (e.g., downstream of the SCR catalyst 106 or upstream of the DPF 102) to oxidize hydrocarbons and carbon monoxide in the exhaust gas.

[0029] In some implementations, the DPF 102 may be positioned downstream of the decomposition chamber or reactor pipe 104. For instance, the DPF 102 and the SCR catalyst 106 may be combined into a single unit, such as an SDPF. In some implementations, the dosing module 112 may instead be positioned downstream of a turbocharger or upstream of a turbocharger.

[0030] The sensor 150 may be coupled to the exhaust system 190 to detect a condition of the exhaust gas flowing through the exhaust system 190. In some implementations, the sensor 150 may have a portion disposed within the exhaust system 190, such as a tip of the sensor 150 may extend into a portion of the exhaust system 190. In other implementations, the sensor 150 may receive exhaust gas through another conduit, such as a sample pipe extending from the exhaust system 190. While the sensor 150 is depicted as positioned downstream of the SCR catalyst 106, it should be understood that the sensor 150 may be positioned at any other position of the exhaust system 190, including upstream of the DPF 102, within the DPF 102, between the DPF 102 and the decomposition chamber 104, within the decomposition chamber 104, between the decomposition chamber 104 and the SCR catalyst 106, within the SCR catalyst 106, or downstream of the SCR catalyst 106. In addition, two or more sensor 150 may be utilized for detecting a condition of the exhaust gas, such as two, three, four, five, or size sensor 150 with each sensor 150 located at one of the foregoing positions of the exhaust system 190

III. Example Process for Selectively Supplying Air from an Air Supply

[0031] In some current systems, continuous air flow is supplied through a nozzle of a dosing module, such as dosing module 112 of Figure 1, to keep the temperature of the nozzle low enough to avoid crystallization of reductant in or around the nozzle by keeping the tip temperature of nozzle near a predetermined value. Such continuous air may also maintain the system in ready-to-dose mode to be able to dose reductant when commanded.

[0032] However, in some instances, there may be periods of time during start-up and/or operation of the system when dosing of reductant may be ineffective or less effective and/or the possibility of crystallization of reductant may be minimal. During such periods, the supply of air from one or more air supply sources, such as air supply source 130 of Figure 1, may be selectively supplied or regulated via a valve. In some instances, the periods when dosing of reductant may be ineffective or less effective may occur when a catalyst temperature, such as SCR catalyst 106 of Figure 1, is below a predetermined threshold temperature. The predetermined threshold temperature may be, for example, 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C, 200 °C, etc. When the catalyst is below the threshold temperature, reduction of NO_x compounds may be less effective and/or negligible. Thus, the dosing of reductant and the supply of air may be stopped. Moreover, when the dosing module and/or the reductant supply system has been previously successfully purged, the possibility of crystallization of reductant within or around the nozzle may be minimal. Thus, stoppage of the supply of air may occur during this period as well.

[0033] The consumption of air from the one or more air supply sources may be reduced during such periods. By reducing the air consumption, increases in fuel efficiency may be achieved, such as by turning off or freewheeling an air pump compressor of an engine and/or turning off an independent air pump that is electrically powered by the engine (thereby reducing the electrical load needed to be generated by an alternator of the engine). In addition, a low or lower rating air compressor may be used based on the reduction in air consumption. In some instances, the reduction in air consumption may reduce the volume needed for an air supply storage device and/or reduce the operational time for an air compressor, thereby permitting a low or lower rating air compressor to be used.

[0034] Figure 2 depicts an example process 200 that may be implemented by a controller, such as controller 120, and/or by a module of the controller, such as an air supply control module. The process 200 may begin (block 202) upon a key-on event, such as when an engine for a vehicle and/or power generator is started, and/or responsive to any other triggering event.

[0035] The process 200 includes determining whether a successful prior purge was completed (block 204). In some implementations, the determination may include interpreting a flag or parameter value, such as a power down parameter, that is indicative of a status of a prior purge that is set after a purge operation of a dosing module for a prior cycle, such as a key cycle. The status of the prior purge may be stored as a value for a parameter or variable during an engine or key-off process, such as a 1 for a prior successful purge or a 0 for a prior unsuccessful purge. If it is determined that the prior purge was not successful (e.g., evaluating that the value for the parameter is a 0), then the process 200 may skip to priming the system (block 210). Skipping to the priming of the system (block 210) may occur to minimize nozzle blockage issues, which can occur due to incomplete purges. That is, if reductant is present in or around the dosing module and/or nozzle, then crystallization may occur as the reductant is heated as the exhaust in the exhaust system is heated. Such crystallization of residue reductant in or around the dosing module and/or nozzle may result in partial and/or complete blockages, thereby reducing the effectiveness of the system.

[0036] If it is determined that the prior purge was successful (e.g., evaluating that the value for the parameter is a 1), then the process 200 proceeds to disabling the air supply for a predetermined period of time (block 206). The air supply may be disabled by commanding a valve, such as valve 132 of Figure 1, to be closed to shut off the supply of air to the dosing module, such as dosing module 112 of Figure 1. The commanding of the valve may include selectively operating the valve responsive to the interpreted parameter indicative of the status to shut off a supply of air to the dosing module for a predetermined period of time. The valve may be within an air supply source, in a conduit fluidly coupling the air supply source to the dosing module, and/or within the dosing module itself. The predetermined period of time may be an amount of time sufficient for the exhaust gas to reach a predetermined temperature (e.g., 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C, 200 °C, etc.) and/or for an inlet of a catalyst to reach a predetermined temperature (e.g., 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C, 200 °C, etc.). The predetermined period of time may be empirically determined based on the temperatures. In some implementations, the predetermined period of time may be between 0 and 30 seconds, such as 15 seconds. The predetermined period of time may be measured from the key-on event and/or any other triggering event. Thus, the air supply may be disabled while the exhaust gas and exhaust system heat up during the initial start-up of the engine.

[0037] In some implementations, the process 200 may include determining whether a temperature of an inlet of a catalyst, such as a SCR catalyst, TSCR, is equal to or greater than a threshold temperature (block 208). In some implementations, determining the temperature of the inlet of the catalyst may include interpreting a value indicative of a temperature of a component of an exhaust system. The interpreted value may be a value received from a sensor, such as a temperature sensor upstream and/or near the inlet of the catalyst, or stored in a data storage, such as a memory or other data storage device. In other implementations, determining the temperature of the inlet of the catalyst may be performed via a feed-forward analysis. The threshold temperature may be a temperature at which the catalyst operates at and/or above a predetermined efficiency. In some implementations, the threshold temperature may be approximately 180 °C. In other implementations, the threshold temperature may be a temperature of approximately 160 °C, 165 °C, 170 °C, 175 °C, 185 °C, 190 °C, 195 °C, 200 °C, etc. In some implementations, the threshold temperature may correspond to (i.e., be the same or equal to) a dosing threshold temperature below which the dosing by the dosing module is stopped. If the temperature of the inlet of the catalyst, TSCR, is below the threshold, the process 200 may return to disabling the air supply for a predetermined period of time (block 206) to allow the temperature to continue to rise. In some implementations, the predetermined period of time may be the same as the predetermined period of time of block 206. In other implementations, the predetermined period of time may be a shorter period of time, such as 1 second, 3 seconds, 5 seconds, 10 seconds, 15 seconds, etc. If the temperature of the inlet of the catalyst, TSCR, is above the threshold temperature, then the process 200 continues to prime the system (block 210). In some implementations, the temperature may be a mid-bed or outlet temperature of the catalyst.

[0038] In some implementations, the step of disabling the air supply for a predetermined period of time (block 206) may be omitted and the process 200 may utilize only the step of determining whether a temperature of an inlet of a catalyst, TSCR, is equal to or greater than a threshold temperature (block 208). In other implementations, the step of determining whether a temperature of an inlet of a catalyst, TSCR, is equal to or greater than a threshold temperature (block 208) may be omitted and the process 200 may utilize only the step of disabling the air supply for a predetermined period of time (block 206).

[0039] The process 200 includes priming the system (block 210). In some instances, priming the system may include selectively operating the valve responsive to the interpreted parameter indicative of the temperature and a predetermined threshold value and/or status of a prior purge to prime the dosing module. The predetermined threshold value may be a temperature value, such as 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C, and/or 200 °C. The status of the prior purge may be stored as a value for a parameter or variable during an engine or key-off process, such as a 1 for a prior successful purge or a 0 for a prior unsuccessful purge. The priming of the system may include controlling the dosing module to not dose any reductant, but allowing reductant to fill any conduits from the reductant source to the dosing module and fill any portions of the dosing module with reductant as needed. The priming of the system may include closing an injector nozzle and/or valve of the dosing module while supplying reductant from a reductant source into the dosing system. In some implementations, a pump may be used in priming the system. In some instances, air from the air supply source may be supplied to the dosing module to pressurize the dosing module during priming. The supplying of air from the air supply to the dosing module may include commanding the valve to open to permit air from the air supply to flow to the dosing module. In some instances, disabling the air supply until priming the system (block 210) may result in approximately 10-20%, such as 15%, of air consumption savings based on the duty cycle of engine. In some implementations, the air supply may be selectively supplied to regulate a temperature of a nozzle of the dosing module.

[0040] In some implementations, the process 200 may terminate after priming the system. In other implementations, the process 200 may continue during operation, as shown in Figure 2.

[0041] The process 200 may include enabling air from the air supply to be provided to the dosing module (block 212). In some instance, the enabling air of the air supply to be provided to the dosing module (block 212) may be combined with the priming of the system (block 210). The enabling of air from the air supply to be provided to the dosing module (block 212) may include commanding the valve to open to permit air from the air supply to flow to the dosing module. That is, a controller may selectively operate the valve to enable air from the air supply to flow to the dosing module.

[0042] The process 200 may include determining whether a temperature of an inlet of a catalyst, such as a SCR catalyst, T_SCR, is equal to or greater than a threshold temperature (block 214) during operation of the engine. In some implementations, determining the temperature of the inlet of the catalyst may include interpreting a value indicative of a temperature of a component of an exhaust system. The interpreted value may be a value received from a sensor, such as a temperature sensor upstream and/or near the inlet of the catalyst, or stored in a data storage, such as a memory or other data storage device. In other implementations, determining the temperature of the inlet of the catalyst may be performed via a feed-forward analysis. The threshold temperature may be a temperature at which the catalyst operates at and/or above a predetermined efficiency. In some implementations, the threshold temperature may be approximately 180 °C. In other implementations, the threshold temperature may be a temperature of, for example, approximately 160 °C, 165 °C, 170 °C, 175 °C, 185 °C, 190 °C, 195 °C, 200 °C, etc. In some implementations, the threshold temperature may correspond to (i.e., be the same or equal to) a dosing threshold temperature below which the dosing by the dosing module is stopped. If the temperature of the inlet of the catalyst, TSCR, is above the threshold, the process 200 may return to enabling of air from the air supply to be provided to the dosing module (block 212) or a dwell step while the temperature of an inlet of a catalyst is at or above the threshold temperature during operation. In some implementations, the temperature may be a mid-bed or outlet temperature of the catalyst.

[0043] If the temperature of the inlet of the catalyst, TSCR, is below the threshold temperature, then the process 200 disables the air supply (block 216). The air supply may be disabled by closing the valve to shut off the supply of air to the dosing module. In some implementations, the disabling of the air supply may be for a predetermined period of time. In some implementations, the predetermined period of time may be based on the determined temperature, such as an amount of time sufficient for the exhaust gas and/or for the catalyst to reach a predetermined temperature. The time may be further based on operating conditions of the engine. In some implementations, the predetermined period of time a constant time, such as the same as the predetermined period of time of block 206. In other implementations, the predetermined period of time may be a shorter period of time, such as, for example, 1 second, 3 seconds, 5 seconds, 10 seconds, 15 seconds, etc. When the air supply is shut off to the dosing module, the exhaust gas may assist in reducing or burning off reductant crystallization from or around the nozzle as the exhaust gas temperature flowing past the nozzle will be approximately 150 to 180 °C, thereby heating up the nozzle or the area around the nozzle while reductant is not being injected. In other

implementations, once the air supply is disabled, the process 200 may return to determining whether a temperature of an inlet of a catalyst, such as a SCR catalyst, TSCR, is equal to or greater than a threshold temperature (block 214). Thus, the air supply may be disabled while the exhaust gas and exhaust system are below the predetermined threshold and re-enabled when the temperature exceeds the predetermined threshold.

[0044] In some implementations, the threshold temperature for disabling the air supply may be different from the threshold temperature for enabling or re-enabling the air supply. For instance, the threshold temperature for disabling the air supply may be 176 °C and the threshold temperature for enabling or re-enabling the air supply may be 180 °C. In some further implementations, the disabling of the air supply may also be based on a dosing command having a zero value (indicative of no dosing being commanded). In some instances, the lower temperature threshold for disabling the air supply may permit the supplied air to clear a reductant transfer line.

[0045] In some implementations, the process 200 may be subdivided into two processes, such as a first process for reduction of air before the system is primed and a second process for reduction of air after the system is primed.

[0046] Figure 3 is a graphical diagram 300 depicting values indicative of temperatures at a catalyst inlet 310 and a threshold value 320. When the values indicative of the temperatures at the catalyst 310 are below the threshold value 320, the process 200 of Figure 2 can selectively disable the supply of air from an air supply. Thus, the consumption of air from one or more air supply sources may be reduced during such periods. By reducing the air consumption, increases in fuel efficiency may be achieved. In addition, a low rating air compressor may be used based on the reduction in air consumption. In some instances, the reduction in air consumption may reduce the volume needed for an air supply storage device and/or reduce the operational time for an air compressor.

[0047] The term "controller" encompasses all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, a portion of a programmed processor, or combinations of the foregoing. The apparatus can include special purpose logic circuitry, e.g., an FPGA or an ASIC. The apparatus can also include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them. The apparatus and execution environment can realize various different computing model infrastructures, such as distributed computing and grid computing infrastructures.

[0048] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).

[0049] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated in a single product or packaged into multiple products embodied on tangible media.

[0050] As utilized herein, the terms "approximately," "substantially", and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided.

Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

Additionally, it is noted that limitations in the claims should not be interpreted as constituting "means plus function" limitations under the United States patent laws in the event that the term "means" is not used therein.

[0051] The terms "coupled," "connected," and the like as used herein mean the joining of two components 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 components or the two components and any additional intermediate components being integrally formed as a single unitary body with one another or with the two components or the two components and any additional intermediate components being attached to one another.

[0052] The terms "fluidly coupled," "in fluid communication," and the like as used herein mean the two components or objects have a pathway formed between the two components or objects in which a fluid, such as water, air, gaseous reductant, gaseous ammonia, etc., may flow, either with or without intervening components or objects. Examples of fluid couplings or configurations for enabling fluid communication may include piping, channels, or any other suitable components for enabling the flow of a fluid from one component or object to another.

[0053] It is important to note that the construction and arrangement of the system shown in the various exemplary implementations is illustrative only and not restrictive in character. All changes and modifications that come within the spirit and/or scope of the described implementations are desired to be protected. It should be understood that some features may not be necessary and implementations lacking the various features may be

contemplated as within the scope of the application, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as "a" or "an" are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the term "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

[0054] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features specific to particular implementations. 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 system, comprising:

an air supply;

a dosing module in selective fluid communication with the air supply;

a valve configured to selectively supply air from the air supply to the dosing module by selectively opening or closing the valve; and

a controller configured to:

interpret a parameter indicative of a temperature of a component of an exhaust system; and

selectively operate the valve to enable or disable the air supply to the dosing module responsive to the interpreted parameter indicative of the temperature and a predetermined threshold value.

2. The system of claim 1 , wherein the controller is configured to selectively operate the valve responsive to the interpreted parameter indicative of the temperature and a predetermined threshold value to prime the dosing module.

3. The system of claim 1 , wherein the controller is configured to selectively operate the valve responsive to the interpreted parameter and a predetermined threshold value to shut off a supply of air to the dosing module during operation of an engine.

4. The system of claim 1 , wherein the controller is further configured to:

interpret a parameter indicative of a status of a prior purge; and selectively operate the valve responsive to the interpreted parameter indicative of the status.

5. The system of claim 4, wherein the controller is configured to selectively operate the valve responsive to the interpreted parameter indicative of the status to shut off a supply of air to the dosing module for a predetermined period of time.

6. The system of claim 1 , wherein the controller is further configured to:

determine a successful prior purge was completed; and

disable the air supply for a predetermined period of time responsive to determining the successful prior purge was completed.

7. The system of claim 6, wherein the predetermined period of time is between 0 and 30 seconds.

8. The system of claim 6, wherein determining a successful prior purge was completed is responsive to a key-on event.

9. The system of claim 1 , wherein the controller is further configured to:

determine a temperature of an inlet of a catalyst is equal to or greater than a threshold temperature; and

enable air from the air supply to be provided to the dosing module responsive to determining the temperature of the inlet of the catalyst is equal to or greater than the threshold temperature.

10. The system of claim 1 , wherein the predetermined threshold value is 180 °C.

1 1. A method for reducing air consumption for a dosing system, the method comprising: dosing reductant into an exhaust system via a dosing module in selective fluid communication with an air supply;

interpreting a first parameter indicative of a first temperature of a component of the exhaust system; and

disabling air to the dosing module from the air supply via a valve responsive to the interpreted first parameter indicative of the first temperature being below a first

predetermined threshold value.

12. The method of claim 11 further comprising:

interpreting a second parameter indicative of a second temperature of the component of the exhaust system; and

enabling air to the dosing module from the air supply via the valve responsive to the interpreted second parameter indicative of the second temperature being above a second predetermined threshold value.

13. The method of claim 12, wherein the second predetermined threshold value is less than the first predetermined threshold value.

14. The method of claim 11 further comprising:

interpreting a parameter value that is indicative of a status of a prior purge; and priming the dosing module responsive to the interpreted parameter indicating a successful prior purge.

15. The method of claim 14, wherein interpreting the parameter value that is indicative of the status of the prior purge is responsive to a key-on event.

16. The method of claim 1 1, wherein disabling air to the dosing module from the air supply via the valve is for a predetermined period of time.

17. The method of claim 11 further comprising:

determining a temperature of an inlet of a catalyst is equal to or greater than a threshold temperature; and

enabling air from the air supply to be provided to the dosing module responsive to determining the temperature of the inlet of the catalyst is equal to or greater than the threshold temperature.

18. A system, comprising:

a temperature sensor;

a dosing module in selective fluid communication with an air supply;

a controller configured to:

dose reductant into an exhaust system via the dosing module in selective fluid communication with the air supply;

interpret a first parameter indicative of a first temperature of a component of the exhaust system measured by the temperature sensor;

disable air from the air supply to the dosing module for a period of time responsive to the interpreted first parameter indicative of the first temperature being below a first predetermined threshold value;

interpret, after the period of time, a second parameter indicative of a second temperature of the component of the exhaust system measured by the temperature sensor; and

enable air from the air supply to the dosing module responsive to the interpreted second parameter indicative of the second temperature being above a second predetermined threshold value.

19. The system of claim 18, wherein the second predetermined threshold value is less than the first predetermined threshold value.

20. The system of claim 18, wherein the predetermined period of time is between 0 and 30 seconds.