Systems and methods for purging reductant from a reductant injector

A reductant insertion system for inserting reductant into an aftertreatment system via a reductant injector comprises a reductant insertion assembly comprising a pump operatively coupled to the reductant injector via a reductant delivery line. A compressed gas source is operatively coupled to the reductant injector and provides a compressed gas to the reductant injector for gas assisted delivery of the reductant. A controller is operatively coupled to the compressed gas source and the reductant insertion assembly and configured to determine whether there is a reductant demand for the reductant. In response to there being no reductant demand, the controller stops the pump and activates the compressed gas source for a predetermined time so as to provide compressed gas to the reductant injector at a pressure sufficient to force reductant contained in the reductant injector upstream towards the reductant insertion assembly via the reductant delivery line while the pump is stopped.

TECHNICAL FIELD

The present disclosure relates generally to aftertreatment systems for use with internal combustion (IC) engines.

BACKGROUND

Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by IC engines. Generally exhaust gas aftertreatment systems include any of several different components to reduce the levels of harmful exhaust emissions present in the exhaust gas. For example, certain exhaust gas aftertreatment systems for diesel-powered IC engines include a selective catalytic reduction (SCR) system including a catalyst formulated to convert NOx (NO and NO2in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3). Generally in such aftertreatment systems, an exhaust reductant, (e.g., a diesel exhaust fluid such as urea) is injected into the SCR system to provide a source of ammonia, and mixed with the exhaust gas to partially reduce the NOx gases. The reduction byproducts of the exhaust gas are then communicated to the catalyst included in the SCR system to decompose substantially all of the NOx gases into relatively harmless byproducts which are expelled out of the aftertreatment system.

A reductant is generally inserted into the SCR system as the source of ammonia to facilitate the reduction of constituents such as NOx gases of the exhaust gas (e.g., a diesel exhaust gas) by the catalyst included in the SCR system. Reductant insertion assemblies which can include pumps, valves, fluid communication lines, nozzles, pressure relief valve, bypass valves, reductant injectors and/or other fluid communication equipment are often used for controlled insertion of the reductant into the aftertreatment system, for example the SCR system of the aftertreatment system.

During a period when a reductant is not being inserted into the SCR system, for example, when a reductant demand is not present or the equipment (e.g., a vehicle) including the aftertreatment system is turned OFF, some reductant may remain in the reductant injector in a flow path of the exhaust gas. Low atmospheric temperature (e.g., temperatures below −11 degrees Celsius) may lead to freezing and expansion of the remaining reductant in the reductant injector and/or reductant delivery line. On the other hand, exposure of the remaining reductant to the high temperature exhaust gas may cause thermal degradation, crystallization and/or cracking of the reductant in the reductant injector. Freezing and/or thermal degradation may lead to partial or full blockage of the reductant delivery line and/or reductant injector, as well as mechanical damage, therefore increasing maintenance costs.

SUMMARY

Embodiments described herein relate generally to systems and methods for purging a reductant injector of a reductant, and in particular, to purging reductant injectors when a reductant demand is not present using at least one of: providing a compressed gas provided to the reductant injector to force the reductant out of the reductant injector and at least part way into a reductant delivery line, reversing a flow direction of a pump of a reductant insertion assembly, and/or providing for gravity assisted drainage of reductant from the reductant injector.

In a first set of embodiments, a reductant insertion system for inserting reductant into an aftertreatment system via a reductant injector comprises a reductant insertion assembly comprising a pump operatively coupled to the reductant injector via a reductant delivery line and configured to pump the reductant to the reductant injector. A compressed gas source is operatively coupled to the reductant injector and configured to provide a compressed gas to the reductant injector for gas assisted delivery of the reductant through the reductant injector. A controller is operatively coupled to the compressed gas source and the reductant insertion assembly. The controller is configured to determine whether there is a reductant demand for the reductant. In response to determining that there is no reductant demand, the controller is configured to stop the pump, and activate the compressed gas source for a predetermined time so as to provide compressed gas to the reductant injector at a pressure sufficient to force reductant contained in the reductant injector upstream towards the reductant insertion assembly via the reductant delivery line while the pump is stopped.

In another set of embodiments, a reductant insertion system for inserting a reductant into an aftertreatment system via a reductant injector comprises a reductant insertion assembly operatively coupled to the reductant injector via a reductant delivery line. The reductant insertion assembly comprises a pump. A controller is operatively coupled to the reductant insertion assembly. The controller is configured to determine whether there is a reductant demand for the reductant. In response to the determining that there is no reductant demand, the controller is configured to activate the pump for reverse flow operation so as to draw any reductant contained in the reductant injector upstream towards the reductant insertion assembly via the reductant delivery line.

In still another set of embodiments, a method for purging a reductant from a reductant injector, having a reductant insertion assembly comprising a pump and operatively coupled to the reductant injector via a reductant delivery line, and a compressed gas source operatively coupled to the reductant injector, comprises determining whether there is a reductant demand for the reductant. In response to the reductant demand being present, the pump is activated so as to pump the reductant into the reductant injector and the compressed gas source is activated so as to provide gas assisted delivery of the reductant through the reductant injector. In response to the determining that there is no reductant demand, the pump is stopped. Furthermore, the compressed gas source is activated for a predetermined time so as to provide the compressed gas to the reductant injector at a pressure sufficient to force reductant contained in the reductant injector upstream towards the reductant insertion assembly via the reductant delivery line while the pump is stopped.

In yet another set of embodiments, a method for purging a reductant from a reductant injector having a reductant insertion assembly comprising a pump and operatively coupled to the reductant injector via a reductant delivery line, and a compressed gas source operatively coupled to the reductant injector, comprises determining whether there is a reductant demand for the reductant. In response to the reductant demand being present, the pump is activated for forward flow operation so as to pump the reductant into the reductant injector via the reductant delivery line, and the compressed gas source is activated so as to provide gas assisted delivery of the reductant through the reductant injector. In response to determining that there is no reductant demand, the pump is activated for reverse flow operation so as to draw reductant contained in the reductant injector upstream towards the reductant insertion assembly via the reductant delivery line.

DETAILED DESCRIPTION

Embodiments described herein relate generally to systems and methods for providing compressed gas to or purging a reductant injector of a reductant and in particular, to purging reductant injectors when a reductant demand is not present using at least one of: providing a compressed gas provided to the reductant injector to force the reductant out of the reductant injector and at least part way into a reductant delivery line, reversing a flow direction of a pump of a reductant insertion assembly, and/or providing for gravity assisted drainage of reductant from the reductant injector.

Some aftertreatment systems are operatively coupled to large engines, for example HHP engines (e.g., having a capacity in the range of 19 liters to 120 liters or even higher) which generate a large amount of exhaust gas. Such aftertreatment systems use a large amount of reductant for reducing constituents of the exhaust gas. The reductant is generally inserted into the aftertreatment system, for example, an SCR system of the aftertreatment system using one or more reductant injectors which may be positioned in a flow path of the exhaust gas. Compressed gas, for example, air or recirculated exhaust gas may also be provided to the reductant injector for gas assisted delivery of the reductant into the SCR system.

During a period when a reductant is not being inserted into the SCR system, for example, when a reductant demand is not present or an equipment (e.g., a vehicle) including the aftertreatment system is turned OFF, some reductant may remain in the reductant injector. Low atmospheric temperature (e.g., temperatures below −11 degrees Celsius) may lead to freezing and expansion of the remaining reductant in a reductant injector and reductant delivery line. On the other hand, exposure of the remaining reductant to the high temperature exhaust gas may cause thermal degradation, crystallization and/or cracking of the reductant in the reductant injector. Freezing and thermal degradation may lead to partial or full blockade of the reductant delivery line and/or reductant injector, as well as mechanical damage increasing maintenance costs.

Some conventional reductant insertion assemblies include a separate bypass valve for purging the reductant injector and reductant delivery lines of the reductant. Such bypass valves purge the reductant and reductant delivery lines to atmospheric pressure and therefore, have to be primed for a subsequent reductant insertion event, which may lead to priming issues. Bypass valves are, also prone to failure and lead to high maintenance costs. Furthermore, a separate bypass system adds additional components to the reductant insertion assembly and may lead to a significant increasing in manufacturing cost.

Various embodiments of the systems and methods described herein for may provide benefits including, for example: (1) purging of reductant remaining in a reductant injector in the absence of a reductant demand, therefore preventing freezing or thermal degradation of the reductant in the reductant injector; (2) enabling reductant to be forced upstream only part of a length of a reductant delivery line so as to prevent purging of the reductant insertion assembly and avoiding priming issues as well as preventing hot exhaust gas from entering the reductant insertion assembly; and (3) reducing manufacturing cost by eliminating use of a bypass valve or other auxiliary components for purging the reductant from the reductant injector.

FIG. 1is a schematic illustration of an aftertreatment system100, according to an embodiment. The aftertreatment system100is configured to receive an exhaust gas (e.g., a diesel exhaust gas) from an engine10and the reduce constituents of the exhaust gas such as, for example, NOx gases, CO, etc. The aftertreatment system100includes a reductant storage tank110, a reductant insertion system120and a SCR system150.

The engine10may include an IC engine, for example a diesel engine, a gasoline engine, a natural gas engine, a biodiesel engine, a dual fuel engine, an alcohol engine, an E85 or any other suitable internal combustion engine. In some embodiments, the engine10may include a HHP engine, for example having a volumetric capacity in the range of 19 liters to 120 liters or even higher, and a rated power of greater than 500 HP.

The reductant storage tank110contains an exhaust reductant formulated to facilitate reduction of the constituents of the exhaust gas (e.g., NOx gases) by a catalyst154included in the SCR system150. In embodiments in which the exhaust gas is a diesel exhaust gas, the exhaust reductant can include a diesel exhaust fluid (DEF) which provides a source of ammonia. Suitable DEFs can include urea, aqueous solution of urea or any other DEF (e.g., the DEF available under the tradename ADBLUE®). In particular embodiments, the reductant includes an aqueous urea solution containing 32.5% urea and 67.5% de-ionized water. In other embodiments, the reductant includes aqueous urea solution containing 40% urea and 60% de-ionized water, or may include any other concertation ratio of urea to deionized water.

While systems and methods are described herein are explained as a reductant insertion system for inserting a reductant into an aftertreatment system, it should be appreciated that the concepts described herein are equally applicable to any other fluid insertion system for inserting a fluid into a system. Such systems may include, for example, a hydrocarbon insertion system for inserting hydrocarbons (e.g., gasoline, diesel, biodiesel, natural gas, ethanol or any other suitable fuel) into an aftertreatment system, for example, for regenerating components of the aftertreatment system (e.g., an oxidation catalyst included in the aftertreatment system).

The SCR system150is configured to receive and treat the exhaust gas (e.g., a diesel exhaust gas) flowing through the SCR system150. The SCR system150is operatively coupled to the reductant storage tank110so as to receive the reductant therefrom via the reductant insertion system120, as described herein. The SCR system150includes a housing152defining an inlet102for receiving the exhaust gas from the engine10, and an outlet104for expelling treated exhaust gas. While shown as including a single inlet102, in various embodiments, the SCR system150may include a plurality of inlets for receiving exhaust gas from the engine10(e.g., from an exhaust manifold thereof). In other embodiments, the aftertreatment system100may include a plurality of SCR systems150, each of the plurality of SCR systems150configured to receive and treat a portion of the exhaust gas produced by the engine10. For example, each of the plurality of SCR systems150may be dedicated to receiving and treating exhaust gas from a subset of a plurality of engine cylinders of the engine10.

A first sensor103may be positioned in the inlet102. The first sensor103may include, for example a NOx sensor (e.g., a physical or virtual NOx sensor), an oxygen sensor, a particulate matter sensor, a carbon monoxide sensor, a temperature sensor, a pressure sensor, any other sensor or a combination thereof configured to measure one or more parameters of the exhaust gas. Furthermore, a second sensor105may be positioned in the outlet104. The second sensor105may include, for example a NOx sensor, a particulate matter sensor, an ammonia oxide (AMOx) sensor, an oxygen sensor, a temperature sensor, a pressure sensor, any other sensor or a combination thereof.

The SCR system150includes at least one catalyst154positioned within an internal volume defined by the housing152. The catalyst154is formulated to selectively reduce constituents of the exhaust gas, for example NOx gases included in the exhaust gas in the presence of the reductant. Any suitable catalyst154can be used such as, for example, platinum, palladium, rhodium, cerium, iron, manganese, copper, vanadium based catalysts (including combinations thereof).

The catalyst154can be disposed on a suitable substrate such as, for example, a 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 catalyst154. Such washcoat materials can include, for example, aluminum oxide, titanium dioxide, silicon dioxide, any other suitable washcoat material, or a combination thereof. The exhaust gas can flow over and about the catalyst154such that NOx gases included in the exhaust gas are further reduced to yield an exhaust gas which is substantially free of carbon monoxide and NOx gases.

The aftertreatment system100also includes a reductant injector140configured to insert the reductant into the SCR system150. The reductant injector140may include, for example, a dosing lance and may be positioned in an exhaust flow path of the exhaust gas flowing through the SCR system150, for example, positioned to insert the reductant along a centerline of the exhaust flow path. The reductant injector140is configured to provide gas assisted delivery of the reductant into the SCR system150. For example, the reductant injector140may be configured to receive reductant from a reductant insertion assembly122and compressed gas (e.g., compressed air o recirculated exhaust gas) from a compressed gas source130included in the reductant insertion system120, and insert a gas-reductant mixture into the SCR system150. As shown inFIG. 1, the reductant injector140is positioned on the housing152of the SCR system150. In other embodiments, the inlet102may include a decomposition chamber or tube to allow the reductant to react with the exhaust gas. In such embodiments, the reductant injector140maybe positioned in the inlet102so as to insert the reductant upstream of the SCR system150.

Any suitable reductant injector may be used as the reductant injector140. For example,FIG. 3is a side cross-section view of a reductant injector340which may be used in the aftertreatment system100, according to an embodiment. The reductant injector340comprises a reductant injector housing341defining an axial reductant channel342having a reductant orifice343define proximate to outlets348of the reductant injector340. The reductant injector housing341further defines one or more compressed gas channels344having a compressed gas orifice345positioned proximate to the reductant orifice343. As shown inFIG. 3, the compressed gas channels344are positioned at an angle with respect to the reductant channel342. In other embodiments, the reductant injector housing341may define one or more compressed gas channels344, positioned perpendicular to, or at any other suitable angle with respect to the reductant channel342.

The reductant injector housing341defines a critical orifice347positioned downstream of the compressed gas orifice345and the reductant orifice343. The critical orifice347leads into a mixing chamber346, and is configured to accelerate the flow of the reductant and compressed gas into the mixing chamber346so as to facilitate mixing of the reductant and compressed gas in the mixing chamber346and/or control a flow rate and/or pressure of the gas-reductant mixture. The outlets348are operatively coupled to the mixing chamber346and configured to insert the gas-reductant mixture into the SCR system (e.g., the SCR system150).

Referring now toFIG. 1, the reductant insertion system120is operatively coupled to the reductant storage tank110and the SCR system150and configured to provide reductant and compressed gas to the reductant injector140. The reductant insertion system120includes the reductant insertion assembly122. The reductant insertion assembly122comprises a pump124. In some embodiments, an upstream pump112is positioned downstream of the reductant storage tank110and upstream of the reductant insertion assembly122. The upstream pump112may include, for example a lift pump (e.g., a diaphragm pump or a piezoelectric pump) operatively coupled to the reductant storage tank110and configured to pump the reductant from the reductant storage tank110to the reductant insertion assembly122at a predetermined upstream pressure and/or flow rate. An upstream pressure sensor114may be positioned upstream of the reductant insertion assembly122and downstream of the upstream pump112. The upstream pressure sensor114may be configured to determine a reductant pressure upstream of the reductant insertion assembly122and generate an upstream pressure signal indicative of the reductant pressure upstream of the reductant insertion assembly122. The upstream pump112may be configured to adjust a pumping pressure thereof so as to provide the reductant to the reductant insertion assembly122at the predetermined upstream pressure and/or flow rate (e.g., a rated inlet pressure and/or flow rate of the reductant insertion assembly122).

The pump124configured to receive the reductant from the reductant storage tank110and pressurize the reductant to an operating pressure of the pump124. The pump124is configured to provide the reductant at a predetermined pressure and/or flow rate to the reductant injector140. In various embodiments, the operating pressure may be in the range of 0.5 bar to 10 bar (e.g., 0.5 bar, 1 bar, 2 bar, 4 bar, 6 bar, 8 bar or 10 bar inclusive of all ranges and values therebetween). The pump124may include any suitable pump, for example a centrifugal pump, a rotary pump, vacuum pump, a plate pump, a diaphragm, a membrane pump or any other suitable pump.

In particular embodiments, the pump124includes a fixed displacement gear pump. An rpm or pumping speed of the pump124included in the reductant insertion assembly122may be adjustable so as to allow the pump124to adjust the operating pressure of the reductant provided to the reductant injector140. In particular embodiments, the pump124may be structured to pump a predetermined volume of the reductant per revolution of the gear or motor of the pump124. In some embodiments, one or more metering valves126may also be included in the reductant insertion assembly122and configured to be selectively opened (e.g., in response to a reductant demand) for providing the reductant to the reductant injector140. One or more nozzles (e.g., the nozzles194a/b/c/dshown inFIGS. 4A-B) may also be positioned downstream of the one or more metering valves126and configured to control a flow rate and/or pressure of the reductant provided to the reductant injector140. A reductant delivery line128fluid couples the reductant insertion assembly122(e.g., the pump124) to the reductant injector140.

In some embodiments, the reductant insertion system120may also include a reductant return line127configured to return at least a portion of the reductant back to the reductant storage tank110from the reductant insertion assembly122, for example, to prevent over pressurization of the pump124. A purge valve129may be positioned in the reductant return line127. The purge valve129may be configured to open in response to a reductant pressure of the reductant exceeding a predetermined pressure threshold.

The reductant insertion system120also comprises a compressed gas source130configured to provide compressed gas to the reductant injector140for gas assisted delivery of the reductant through the reductant injector140. In some embodiments, the compressed gas source130may include an air tank configured to store compressed air, such that the compressed gas comprises compressed air. In other embodiments, the compressed gas source130may comprise an exhaust gas recirculation line configured to recirculate at least a portion of the exhaust gas to the reductant injector140, such that the compressed gas comprises exhaust gas. In some embodiments, the compressed gas source130may also include a compressor configured to pressurize the gas (e.g., air or recirculated exhaust gas) to a predetermined gas pressure. The compressed gas source130may also include a gas valve132configured to be selectively opened so as to allow the compressed gas to be provided to the reductant injector140via a gas delivery line134.

In particular embodiments, the reductant insertion system120also comprises a controller170. The controller170is communicatively coupled to the reductant insertion assembly122and the compressed gas source130. The controller170may be configured to determine whether there is a reductant demand for the reductant. For example, the controller170may also be communicatively coupled to the engine10, the first sensor103and/or the second sensor105. The controller170may receive signals from the engine10corresponding to one or more engine operating parameters (e.g., engine speed, torque, power, air-fuel ratio, exhaust flow rate, etc.), from the first sensor103corresponding to amount of NOx gases in the exhaust gas entering the SCR system150, and/or from the second sensor105corresponding to an amount of NOX gases in the treated exhaust gas being expelled into the environment. The controller170may be configured to interpret one or more of these signals to determine if the reductant should be inserted into the SCR system150(i.e., if a reductant demand for the reductant). The controller170may also be configured to determine a volume, a flow rate, a pressure, an insertion timing and/or an insertion frequency of a reductant to be inserted into the SCR system150using one or more of the signals received from the engine10, the first sensor103and/or the second sensor105.

The controller170may be configured to selectively activate the reductant insertion assembly122(e.g., activate the pump124and open the metering valve126) and the compressed gas source130(e.g., open the gas valve132), for example, in response to a reductant demand being present. Activating the pump124causes the reductant to be pumped into the reductant injector140. Furthermore, activating the compressed gas source130(e.g., opening the gas valve132) causes the compressed gas source130to provide the compressed gas (e.g., compressed air or recirculated exhaust gas) to the reductant injector140so as to provide gas assisted delivery of the reductant through the reductant injector140.

In some embodiments, in response to the reductant demand being not present, (e.g., when exhaust gas pressure or flow rate is low, at engine10startup and/or engine10OFF conditions) the controller170may be configured to stop the pump124and activate the compressed gas source130(e.g., open the gas valve132) for a predetermined time so as to provide compressed gas to the reductant injector140(e.g., without the pump124being activated and/or with the metering valve126being closed). The compressed gas may force the reductant contained in the reductant injector140upstream towards the reductant insertion assembly122via the reductant delivery line128while the pump is stopped, therefore purging the reductant injector140of the reductant when there is no reductant demand. For example with reference toFIG. 3, with the pump124turned OFF and the metering valve126open, the compressed gas flowing through the gas channel344towards the critical orifice347may have sufficient pressure such that at least a portion of the compressed gas flows through the reductant orifice343into the reductant channel342, as shown by the arrows A and B, so as to force the reductant upstream into the reductant delivery line128.

In some embodiments, the compressed gas may have a pressure sufficient to force the reductant contained in the reductant injector140upstream into the reductant delivery line128such that at least a portion of a length of the reductant delivery line128downstream of the reductant insertion assembly122remains filled with the reductant. In other words, the compressed gas may force the reductant only part way through the reductant delivery line128. This may prevent the hot exhaust gas from flowing upstream through the reductant delivery line128into the reductant insertion assembly122which may damage the components of the reductant insertion assembly122, and also prevent priming issues by preventing the reductant delivery line128from being completely purged of the reductant.

In other embodiments, the compressed gas may have a pressure sufficient to force the reductant contained in the reductant injector140completely into the reductant insertion assembly122through the reductant delivery line128such that the reductant delivery line128is substantially empty of the reductant. In other embodiments, the controller170may be configured to also move the purge valve129into an open configuration so as to allow at least a portion of the reductant to be force towards the reductant storage tank110through the reductant return line127. In such embodiments, the compressed gas pressure may be sufficient to force the reductant only a portion of a length of the reductant return line127or substantially empty the reductant return line127.

In some embodiments, in response to the reductant demand being not present, the controller170may be additionally or alternatively configured to activate the pump124for reverse flow operation so as to draw any reductant contained in the reductant injector140upstream towards the reductant insertion assembly122. For example, the pump124may include a fixed displacement gear pump configured for reversible flow operation, for example, forward flow operation configured to pump the reductant towards the reductant injector140, as well as reverse flow operation configured to draw the reductant from the reductant injector140towards the pump124. A pulse width modulated (PWM) signal may be used to control the operation of the pump124.

In some embodiments, the controller170may be configured to activate the pump124for a first predetermined time such that at least a portion of a length of the reductant delivery line128downstream of the reductant insertion assembly122remains filled with the reductant. For example, the pump124may be activated for a first predetermined number of revolutions or a fixed displacement in the reverse flow operation during the first predetermined time. Reverse flow operation exerts a negative pressure in the reductant delivery line128causing the reductant contained in the reductant injector140to be drawn under the negative pressure towards the pump124. The first predetermined number of revolutions, fixed displacement, or operation for the first predetermined time may be configured to draw the reductant a predetermined distance into the reductant delivery line128. When a reductant demand is present, the pump124may be operated in the forward flow operation for the first predetermined number of revolutions, the fixed displacement or for the predetermined time for priming the reductant injector140.

In some embodiments, the controller170may be configured to activate the pump124for a second predetermined time such that substantially all of the reductant is drawn from the reductant injector140and the reductant delivery line128into the pump124, such that the reductant delivery line128is substantially empty of the reductant. The second predetermined time, may be configured to operate the pump124in reverse flow operation for a second predetermined number of revolutions or displacement so as to draw the reductant contained in the reductant injector140and the reductant delivery line128into the pump124such that the reductant delivery line128is substantially empty of the reductant.

In other embodiments, the controller170may be configured to also move the purge valve129into an open configuration so as to allow at least a portion of the reductant contained with the reductant return line127to also be drawn towards the pump124and back towards the reductant storage tank110. In such embodiments, the pump124may be operated any length of time in reverse flow mode (e.g., a predetermined number of revolutions or a fixed displacement) so as to withdraw the reductant from the reductant return line127such that a portion of the length of the reductant return line127contains reductant, or the reductant return line127is substantially empty of the reductant.

In some embodiments, additionally or alternatively, at least a portion of the reductant insertion assembly122may be positioned at a lower elevation relative to the reductant injector140, for example mounted below the reductant injector140. This may cause the reductant contained in the reductant injector140to flow upstream towards the reductant insertion assembly122under the influence of gravity when the reductant demand is not present, thereby purging the reductant injector140.

In particular embodiments, the controller170may be included in a control circuitry. For example,FIG. 2is a schematic block diagram of a control circuitry171that comprises the controller170, according to an embodiment. The controller170comprises a processor172, a memory174, or any other computer readable medium, and a communication interface176. Furthermore, the controller170includes a reductant demand determination circuitry174a, a compressed gas insertion control circuitry174band a pump control circuitry174c. It should be understood that the controller170shows only one embodiment of the controller170and any other controller capable of performing the operations described herein can be used.

The processor172can comprise a microprocessor, programmable logic controller (PLC) chip, an ASIC chip, or any other suitable processor. The processor172is in communication with the memory174and configured to execute instructions, algorithms, commands, or otherwise programs stored in the memory174.

The memory174comprises any of the memory and/or storage components discussed herein. For example, memory174may comprise a RAM and/or cache of processor172. The memory174may also comprise one or more storage devices (e.g., hard drives, flash drives, computer readable media, etc.) either local or remote to controller170. The memory174is configured to store look up tables, algorithms, or instructions.

In one configuration, the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174care embodied as machine or computer-readable media (e.g., stored in the memory174) that is executable by a processor, such as the processor172. As described herein and amongst other uses, the machine-readable media (e.g., the memory174) facilitates performance of certain operations 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.).

In another configuration, the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174care embodied as hardware units, such as electronic control units. As such, the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174cmay 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.

In some embodiments, the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174cmay 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 demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174cmay 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.

Thus, the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174cmay also include programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. In this regard, reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174cmay include one or more memory devices for storing instructions that are executable by the processor(s) of the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174c. The one or more memory devices and processor(s) may have the same definition as provided below with respect to the memory174and the processor172.

In the example shown, the controller170includes the processor172and the memory174. The processor172and the memory174may be structured or configured to execute or implement the instructions, commands, and/or control processes described herein with respect the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174c. Thus, the depicted configuration represents the aforementioned arrangement where the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174care 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 demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174c, or at least one circuit of the reductant demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174care configured as a hardware unit. All such combinations and variations are intended to fall within the scope of the present disclosure.

The processor172may 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 demand determination circuitry174a, the compressed gas insertion control circuitry174band the pump control circuitry174c) 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 co-processors. 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 memory174(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 memory174may be communicably connected to the processor172to provide computer code or instructions to the processor172for executing at least some of the processes described herein. Moreover, the memory174may be or include tangible, non-transient volatile memory or non-volatile memory. Accordingly, the memory174may 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.

The communication interface176may 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 interface176may 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, for example, the first sensor103, the second sensor105, the engine10, and the reductant insertion system120(e.g., the reductant insertion assembly122and the compressed gas source130). The communication interface176may 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.).

The reductant demand determination circuitry174amay be configured to determine whether there is a reductant demand for the reductant or not. For example, the reductant demand determination circuitry174amay receive a signal from the engine10indicative of one or more engine operating parameters (e.g., an intake air volume or flow rate, a fuel/air ratio, and engine speed or torque, etc.) and use the engine operating parameters to determine if there is a reductant demand for the reductant, for example, whether the reductant should be inserted into the SCR system150, a volume, pressure and/or a flow rate of the reductant to be inserted into the SCR system150, and/or an insertion timing and/or insertion frequency of reductant to be inserted into the SCR system150. In other embodiments, the reductant demand determination circuitry174amay additionally or alternatively be configured to receive a first sensor signal from the first sensor103and/or a second sensor signal from the second sensor105indicative of, for example, an amount of NOx gases included in the exhaust gas, and exhaust gas flow rate and/or an amount of NOx gases included in the treated exhaust gas expelled from SCR system150, respectively and determine the reductant demand therefrom.

The compressed gas insertion control circuitry174bmay generate a compressed gas signal configured to selectively activate the compressed gas source130, and the pump control circuitry174cmay generate a pump signal configured to selectively activate the pump124included in the reductant insertion assembly122. For example, the compressed gas insertion control circuitry174bmay be configured to selectively activate compressed gas source130(e.g., open the gas valve132) and the pump control circuitry174cmay be configured to selectively activate the pump124(e.g., start the pump124and open the metering valve126), for example, in response to there being a reductant demand for the reductant. Activating the pump124causes the reductant to be pumped into the reductant injector140. Furthermore, activating the compressed gas source130(e.g., opening the gas valve132) causes the compressed gas source130to provide the compressed gas (e.g., compressed air or recirculated exhaust gas) to the reductant injector140so as to provide gas assisted delivery of the reductant through the reductant injector140.

In response to determining that there is no reductant demand, (e.g., when exhaust gas pressure and/or flow rate is low, at engine10startup and/or engine10OFF conditions) the pump control circuitry174cmay be configured to stop the pump124, and the compressed gas insertion control circuitry174bmay be configured to activate the compressed gas source130for a predetermined time so as to provide compressed gas to the reductant injector140(e.g., with the pump124being stopped and/or with the metering valve126being closed). The compressed gas may have a pressure sufficient to force the reductant contained in the reductant injector140upstream towards the reductant insertion assembly122via the reductant delivery line128, therefore purging the reductant injector140of the reductant when there is no reductant demand. In some embodiments, the compressed gas may have a compressed gas pressure sufficient to force the reductant contained in the reductant injector140upstream into the reductant delivery line128such that at least a portion of a length of the reductant delivery line128downstream of the reductant insertion assembly122remains filled with the reductant. In other embodiments, the compressed gas may have a compressed gas pressure sufficient to force the reductant contained in the reductant injector140completely into the reductant insertion assembly122through the reductant delivery line128such that the reductant delivery line128is substantially empty of the reductant.

In some embodiments, in response to the reductant demand being not present, the pump control circuitry174cmay be configured to activate the pump124for reverse flow operation so as to draw any reductant contained in the reductant injector140upstream towards the reductant insertion assembly122. For example, the pump124may include a fixed displacement gear pump configured for reversible flow operation, for example, forward flow operation configured to pump the reductant towards the reductant injector140, as well as reverse flow operation configured to draw the reductant from the reductant injector140towards the pump124. In some embodiments, the pump control circuitry174cmay be configured to activate the pump124for a first predetermined time such that at least a portion of a length of the reductant delivery line128downstream of the reductant insertion assembly122remains filled with the reductant, as previously described herein. In some embodiments, the controller170may be configured to activate the pump124for a second predetermined time such that substantially all of the reductant is drawn from the reductant injector140and the reductant delivery line128into the pump124, and the reductant delivery line128is substantially empty of the reductant, as previously described herein

In other embodiments, the pump control circuitry174cmay also be configured to move the purge valve129into an open configuration so as to allow at least a portion of the reductant contained in the reductant return line127to be drawn towards the pump124as the pump124is operating in reverse flow operation. In such embodiments, the pump124may be operated any length of time in reverse flow mode (e.g., a predetermined number of revolutions or a fixed displacement) so as to withdraw the reductant contained in the reductant return line127such that a portion of the length of the reductant return line127contains reductant, or the reductant return line127is substantially empty of the reductant.

FIG. 4Ais a schematic illustration of a fluidic circuit402afor providing reductant to an SCR system of an aftertreatment system (e.g., the SCR system150included in the aftertreatment system100) which includes the reductant insertion system120, via the reductant injector140, according to an embodiment. The fluidic circuit402aincludes the reductant storage tank110which stores a volume of the reductant (e.g., a diesel exhaust fluid). A tank filter111may be positioned in the reductant storage tank110, for example at an inlet of a reductant delivery line128operatively coupled to the reductant storage tank110. The tank filter111may be configured to filter reductant deposits or crystals, or contaminants (e.g., dust, debris, etc.) from the reductant so as to prevent such deposits, crystals or contaminants from entering the reductant delivery line128.

An upstream pump112may be positioned in the reductant delivery line128and configured to pump the reductant from the reductant storage tank110to the pump124positioned downstream thereof. The upstream pump112may comprise a lift pump. A reductant filter115may be positioned in the reductant delivery line128downstream of the upstream pump112and the upstream of the pump124. The reductant filter115may be configured to filter reductant deposits or contaminants from the reductant and may also include a bypass circuit, for example to recirculate at least a portion of the reductant therein (e.g., to prevent excessive reductant pressure buildup).

The pump124may be positioned downstream of the reductant filter115. A urea quality sensor116, a temperature sensor118, and an upstream pressure sensor114may be positioned upstream of the pump124. The urea quality sensor116is configured to measure a percentage of urea in the reductant (e.g., an aqueous urea solution). The temperature sensor118may be configured to measure a temperature of the reductant communicated to the pump124. Furthermore, the upstream pressure sensor114may be configured to measure an upstream reductant pressure upstream of the pump124. The upstream pump112may be configured to adjust a pumping pressure thereof based on the upstream reductant pressure, so as to provide the reductant to the pump124at a predetermined upstream reductant pressure and/or flow rate (e.g., a rated inlet pressure and/or flow rate of the pump124).

A downstream pressure sensor123may be positioned downstream of the pump124, and configured to measure a reductant pressure downstream of the pump124. The pump124may be configured to adjust a pumping pressure thereof based on the downstream reductant pressure so as to provide the reductant to a plurality of metering valves126a/b/c/dat a predetermined reductant pressure and/or flow rate. The purge valve129is operably coupled to the reductant return line127. The purge valve129is configured to be selective activated to redirect the reductant flow away from a pump outlet of the pump124and towards the reductant storage tank110via the reductant return line127, for example to reduce a reductant pressure in the plurality of metering valves126a/b/c/d, as previously described herein.

The pump124is operatively coupled to each of the plurality of metering valves126a/b/c/dpositioned within a metering manifold141. A first nozzle194a, a second nozzle194b, a third nozzle194c, and a fourth nozzle194dmay be positioned downstream of the first metering valve126a, the second metering valve126b, the third metering valve126cand the fourth metering valve126d, respectively. Each of the nozzles194a/b/c/dmay have a predetermined nozzle diameter configured to provide the reductant to the reductant injector140at a predetermined pressure and flow rate corresponding to a diameter of the nozzles194a/b/c/d. The nozzle diameter of the each of the nozzles194a/b/c/dmay be different from each other (e.g., in a range of 0.1 mm to 1.0 mm), and configured to provide the reductant to the reductant injector140(e.g., one or more reductant injectors) at a particular pressure and flow rate based on the operating pressure of the reductant provided by the pump124and the corresponding nozzle diameter. In particular embodiments, the first nozzle194amay have a nozzle diameter of 0.7 mm, the second nozzle194bmay have a nozzle diameter of 0.5 mm, the third nozzle194cmay have a nozzle diameter of 0.3 mm, and the fourth nozzle194dmay have a nozzle diameter of 1.0 mm.

A reductant outlet pressure sensor147and a reductant outlet temperature sensor161may be positioned downstream of the nozzles194a/b/c/d. The reductant outlet pressure sensor147may be configured to measure a reductant outlet pressure of the reductant downstream of the nozzles194a/b/c/d. The pump124may be configured to adjust a pumping pressure thereof based on the reductant outlet pressure downstream of the nozzles194a/b/c/d, for example to allow delivery of the reductant to the reductant injector140at a target pressure and/or target flow rate. Furthermore, the reductant outlet temperature sensor161may be configured to measure a temperature of the reductant downstream the reductant nozzles194a/b/c/d.

The compressed gas source130is also be coupled to the reductant injector140, and configured to provide compressed gas (e.g., air or recirculated exhaust gas) for mixing with the reductant and providing gas assisted reductant delivery through the reductant injector140. The gas valve132may be positioned downstream of the compressed gas source130and configured to control an amount of gas mixed with the reductant. In some embodiments, an aftertreatment system (e.g., the aftertreatment system100) including the reductant insertion system120may include a turbocharger. In such embodiments, the compressed gas (e.g., air) may be drawn from a turbine of the turbocharger and/or a compressor inlet of a compressor of the turbocharger. The reductant insertion system120may also include a mixer or blender configured to mix the gas with the reductant communicated to the insertion unit, so as to provide gas-assisted reductant insertion into the SCR system (e.g., the SCR system150). In other embodiments, the mixing is performed in a mixing chamber (e.g., the mixing chamber346) included in the reductant injector140(e.g., the reductant injector340).

FIG. 4Bis a schematic illustration of a fluidic circuit402bwhich may include the reductant insertion system120, according to another embodiment. The fluidic circuit402bofFIG. 4Bis substantially similarly to the fluidic circuit402aofFIG. 4Aexcept for the following differences.

The fluidic circuit402bshown inFIG. 4Bdoes not include the purge valve129shown inFIG. 4A. Instead, the reductant return line127is operatively coupled to the reductant delivery line128upstream of the pump124. In operation, the upstream pump112operates at a constant flow rate which is always greater than a flow rate required by the pump124for insertion of the reductant into the reductant injector140via any one of the metering valves126a/b/c/d. A reductant first portion of the reductant pumped by the upstream pump112through the reductant delivery line128is received by the pump124. The pump124pressurizes the reductant first portion and pumps it to the metering valves126a/b/c/dand therefrom, to the reductant injector140. A reductant second portion of the reductant is returned to the reductant storage tank110via the reductant return line127. Since the reductant second portion is always returned to the reductant storage tank110, the purge valve129can be excluded, thereby reducing complexity while providing protection from over-pressurization of the reductant insertion assembly122.

FIG. 5is a schematic flow diagram of an example method500for purging a reductant from a reductant injector (e.g., the reductant injector140) having a reductant insertion assembly (e.g., the reductant insertion assembly122) and a compressed gas source (e.g., the compressed gas source130) operatively coupled thereto. While described with respect to the reductant insertion system120, the operations of the method500may be used with any other reductant insertion assemblies described herein.

The method500comprises determining whether there is a reductant demand for the reductant, at502. For example, the reductant demand determination circuitry174amay receive an engine signal from the engine10indicative of one or more engine operating parameters (e.g., an intake air volume or flow rate, a fuel/air ratio, and engine speed or torque, etc.) and use the engine operating parameters to determine the reductant demand, for example, whether a reductant has to inserted into the SCR system150, a volume, pressure and/or a flow rate of the reductant to be inserted into the SCR system150, and/or an insertion timing and/or insertion frequency of reductant to be inserted into the SCR system150. In other embodiments, the reductant demand determination circuitry174amay additionally or alternatively be configured to receive a first sensor signal from the first sensor103and/or a second sensor signal from the second sensor105indicative of, for example, an amount of NOx gases included in the exhaust gas and/or exhaust gas flow rate, and/or an amount of NOx gases included in the treated exhaust gas expelled from SCR system150, respectively and determine the reductant demand therefrom.

At504, the method500determines if a reductant demand is present, i.e., whether a reductant has to be inserted into the SCR system at a particular time point. In response to there being a reductant demand for the reductant (504:YES), the pump is activated to pump reductant into the reductant injector, at506. For example, the pump control circuitry174cmay generate a pump signal configured to selectively activate the pump124and the metering valve126of the reductant insertion assembly122in response to a reductant demand being present. Activating the pump124causes the reductant to be pumped into the reductant injector140. At508, the compressed gas source is activated to provide gas assisted delivery of the reductant through the reductant injector. For example, the compressed gas insertion control circuitry174bmay generate a compressed gas signal configured to activate the compressed gas source130(e.g., open the gas valve132) to provide compressed gas (e.g., air or recirculated exhaust gas) to the reductant injector140for providing gas assisted delivery of the reductant through the reductant injector140.

If at504, it is determined that there is no reductant demand (504:NO), the pump is stopped, at510. For example, the pump control circuitry174cmay instruct the pump124to stop. At512, the compressed gas source is activated for a predetermined time so as to provide compressed gas to the reductant injector. For example, in response to the reductant demand being not present, the compressed gas insertion control circuitry174bactivates the compressed gas source130(e.g., opens the gas valve132), for example, with the pump124being inactive (e.g., in an OFF state) and/or the metering valve126being closed. The compressed gas may have sufficient pressure to force reductant contained in the reductant injector140upstream towards the reductant insertion assembly122, as previously described herein. In some embodiments, the compressed gas may have a compressed gas pressure sufficient to force the reductant upstream in the reductant delivery line128such that at least a portion of a length of the reductant delivery line128downstream of the reductant insertion assembly122remains filled with the reductant. In other embodiments, the compressed gas may have a compressed gas pressure sufficient to completely force all of the reductant into the reductant insertion assembly122through the reductant delivery line128such that the reductant delivery line128is substantially empty of the reductant.

In some embodiments, the pump (e.g., the pump124) included in the reductant insertion assembly (e.g., the reductant insertion assembly122) may include a reversible flow pump (e.g., a fixed displacement gear pump). In such embodiments, the method500may additionally or alternately comprise activating the pump for reverse flow operation so as to draw the reductant contained in the reductant injector upstream towards the reductant insertion assembly, at514. For example, the pump control circuitry174cmay activate the pump124for reverse flow operation so as to draw the reductant from the reductant injector140towards the pump124. In some embodiments, the pump124may be activated for a first predetermined time such that at least a portion of a length of the reductant delivery line128downstream of the reductant insertion assembly122remains filled with the reductant, as previously described herein. In other embodiments, the pump124may be activated for a second predetermined time such that substantially all of the reductant is drawn from the reductant injector140and the reductant delivery line128into the pump124, and the reductant delivery line128is substantially empty of the reductant, as previously described herein.

In some embodiments, the method500may also include opening a purge valve for a predetermined time, at516. For example, the pump control circuitry174cmay also be configured to move the purge valve129into an open configuration so as to allow at least a portion of the reductant contained in the reductant return line127to be drawn towards the pump124as the pump124is operating in reverse flow operation, as previously described herein.

In some embodiments, the controller170, the control circuitry171, the controllers or any of the controllers described herein can be a system computer of an apparatus or system which includes the reductant insertion system120(e.g., a vehicle, an engine or generator set, etc.). For example,FIG. 6is a block diagram of a computing device630in accordance with an illustrative implementation. The computing device630can be used to perform any of the methods or the processes described herein, for example the method500. In some embodiments, the controller170or the control circuitry171can include the computing device630. The computing device630includes a bus632or other communication component for communicating information. The computing device630can also include one or more processors634or processing circuits coupled to the bus for processing information.

The computing device630also includes main memory636, such as a random access memory (RAM) or other dynamic storage device, coupled to the bus632for storing information, and instructions to be executed by the processor634. Main memory636can also be used for storing position information, temporary variables, or other intermediate information during execution of instructions by the processor634. The computing device630may further include a read only memory (ROM)638or other static storage device coupled to the bus632for storing static information and instructions for the processor634. A storage device640, such as a solid-state device, magnetic disk or optical disk, is coupled to the bus640for persistently storing information and instructions.

The computing device630may be coupled via the bus632to a display635, such as a liquid crystal display, or active matrix display, for displaying information to a user. An input device642, such as a keyboard or alphanumeric pad, may be coupled to the bus632for communicating information and command selections to the processor634. In another implementation, the input device642has a touch screen display644.

According to various implementations, the processes and methods described herein can be implemented by the computing device630in response to the processor634executing an arrangement of instructions contained in main memory636(e.g., the operations of the method500). Such instructions can be read into main memory636from another non-transitory computer-readable medium, such as the storage device640. Execution of the arrangement of instructions contained in main memory636causes the computing device630to perform the illustrative processes described herein. One or more processors in a multi-processing arrangement may also be employed to execute the instructions contained in main memory636. In alternative implementations, hard-wired circuitry may be used in place of or in combination with software instructions to effect illustrative implementations. Thus, implementations are not limited to any specific combination of hardware circuitry and software.

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).