Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
  • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
  • F01N3/2066—Selective catalytic reduction [SCR]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
  • F01N2550/05—Systems for adding substances into exhaust
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2610/00—Adding substances to exhaust gases
  • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2610/00—Adding substances to exhaust gases
  • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
  • F01N2610/1426—Filtration means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
  • F01N2900/06—Parameters used for exhaust control or diagnosing
  • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
  • F01N2900/1806—Properties of reducing agent or dosing system
  • F01N2900/1808—Pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
  • F01N2900/06—Parameters used for exhaust control or diagnosing
  • F01N2900/18—Parameters used for exhaust control or diagnosing said parameters being related to the system for adding a substance into the exhaust
  • F01N2900/1806—Properties of reducing agent or dosing system
  • F01N2900/1812—Flow rate
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the present disclosure relates generally to detecting filter permeability degradation in a reductant dosing system for exhaust aftertreatment of a diesel engine, and more particularly to a strategy for detecting degraded permeability of a sock filter in a reductant tank.
• exhaust aftertreatment systems Many machines that utilize a diesel engine for power now include exhaust aftertreatment systems.
• One purpose of these aftertreatment systems is to reduce the presence of NOx at the exhaust tailpipe. Typically, this is accomplished by injecting a reductant, such as urea, into the exhaust pipe upstream from a selective catalytic reduction (SCR) catalyst, where the NOx is converted to nitrogen and other more acceptable compounds.
• SCR selective catalytic reduction
• the reductant, or urea, utilized for this process is supplied from a tank carried by the machine. When the tank is in need of being refilled, dirt and debris can enter the tank along with the reductant. The risk of dirt and debris entering the reductant tank can be many times more problematic in the case of off road machines that must operate in dirt and debris filled environments.
• reductant dosing injectors require some minimum fluid pressure in order to operate properly. Furthermore, the nozzle outlets of the reductant injector must remain open and free of clogs.
• U.S. Patent Application Publication 2012/0286063 teaches a urea injector diagnostic strategy that detects system faults in part by monitoring delivery line pressure for the reductant dosing injector.
• the present disclosure is directed toward one or more of the problems set forth above.
• an engine is mounted on a chassis and includes an exhaust aftertreatment system.
• the exhaust aftertreatment system includes a reductant dosing system that has a reductant tank with a fluid level sensor in communication with an electronic controller.
• the reductant tank includes a filter separating an inlet volume from an outlet volume.
• the fluid level sensor is positioned in the outlet volume.
• the tank includes an inlet that opens to the inlet volume, and an outlet that opens to the outlet volume.
• the electronic controller includes a filter status algorithm configured to detect a filter permeability condition based at least in part on data from the fluid level sensor.
• a method of operating a machine includes running an engine supported on a chassis of the machine. Exhaust is moved through an exhaust pipe from the engine. Reductant is circulated around a fluid circuit from an outlet volume of a reductant tank, through a pump and into a return line that opens back into the outlet volume. Reductant is dosed into the exhaust pipe of the engine. Reductant is moved from the inlet volume to the outlet volume of the reductant tank through a filter.
• Tank level data is communicated from a fluid level sensor, which is positioned in the outlet volume, to an electronic controller. Tank level data is compared to expected data. A filter permeability condition is logged responsive to the tank level data differing from the expected data by greater than a predetermined threshold.
• Fig. 1 is a side view of a machine according to one aspect of the present disclosure
• Fig. 2 is a schematic view of an engine and exhaust aftertreatment system according to the present disclosure
• Fig. 3 is an exploded view of a reductant tank header and a sock filter according to the present disclosure
• Fig. 4 is a schematic view of a reductant tank showing a filter permeability condition according to the present disclosure.
• Fig. 5 is a logic flow diagram of a reductant dosing algorithm that includes a filter status algorithm according to the present disclosure.
• a machine 10 includes an engine 15 mounted on a chassis 11.
• the engine includes an exhaust
• machine 10 is shown as a mobile backhoe loader off-road machine in which chassis 11 is supported by a conveyance 12. Nevertheless, those skilled in the art will appreciate that a machine according to the present disclosure could also be stationary, such that the engine were supported on a stationary chassis, or the chassis could be the hull framework of a seagoing vessel without departing from the present disclosure.
• Machine 10 includes an operator station 13 that includes various system status displays of a type well known in the art. Nevertheless, those skilled in the art will appreciate that in other versions of the invention system status information may be transmitted to a remote location, such as for instance in the case of a stationary generator.
• the exhaust aftertreatment system 16 includes a reductant dosing system 20 that includes a reductant tank 21 with a fluid level sensor 22 in communication with an electronic controller 23.
• a reductant dosing system 20 that includes a reductant tank 21 with a fluid level sensor 22 in communication with an electronic controller 23.
• reductant dosing system 20 injects reductant, such as urea, into an exhaust pipe 17 to facilitate a NOx reduction reaction at SCR catalyst 38.
• the Electronic controller 23 may be configured to control the reductant dosing rate from injector 34 in order to match the NOx content in the exhaust stream so as to avoid either ammonia slip or NOx slip at the tailpipe where the exhaust aftertreatment system vents the treated engine exhaust to atmosphere.
• the reductant tank 21 includes a filter 24 separating an inlet volume 25 from an outlet volume 26.
• the fluid level sensor 22, which may be a float sensor, is positioned in the outlet volume 26.
• Tank 21 also includes an inlet 27 that opens to the inlet volume 25 and an outlet 28 that opens to the outlet volume 26.
• the inlet 27 to reductant tank 21 is shown on the outer surface of machine 10 and serves as the means by which tank 21 may be periodically refilled with reductant as needed.
• Filter 24 is included to prevent the dirt and debris that enters into inlet volume 25 from entering into the outlet volume 26.
• filter 24 is shown as a sock filter, but could take other
• the reductant tank could be configured to simply separate the inlet volume from the outlet volume by a vertical wall which would include a wall filter without departing from the intended scope of the present disclosure.
• Fluid circuit 30 includes outlet 28, pump 31 and return line 32 that opens into outlet volume 26.
• a second filter 33 is positioned in fluid circuit 30.
• Pump 31 may draw reductant fluid initially through a screen filter 39 located in outlet volume 26, past outlet 28 and then through filter 33 prior to either arriving at injector 34 or being returned to outlet volume 26 via return line 32.
• a screen filter 39 located in outlet volume 26, past outlet 28 and then through filter 33 prior to either arriving at injector 34 or being returned to outlet volume 26 via return line 32.
• reductant in inlet volume 25 flows through sock filter 24 into outlet volume 26 in order to maintain the fluid level of reductant 37 in inlet volume 25 equal to that in outlet volume 26.
• filter 33 may be provided to prevent any tiny particulate matter that passed through both sock filter 24 and screen filter 39 from potentially plugging the nozzle outlets of injector 34.
• a pressure regulator 40 which is shown as a flow restriction, serves to help maintain injection level pressure in fluid circuit 30.
• Electronic controller 23 may monitor pressure and fluid circuit 30 via a pressure sensor 35.
• pump 31 may have a variable output capability (e.g. variable speed). This permits electronic controller 23 is in control communication with pump 31 to increase or decrease the pump rate responsive to system pressure as communicated by pressure sensor 35.
• Electronic controller 23 also includes a filter status algorithm configured to detect a filter permeability condition for filter 24 based at least in part on data from fluid level sensor 22 communicated to electronic controller 23.
• reductant tank 21 may include a header 29 with an annular surface that receives the open end of sock filter 24.
• sock filter 24 is attached to header 29 with a suitable clamp 36.
• the reductant dosing system 20 may continue to be fully operational without any degraded performance.
• this system permeability condition would go undetected and unnoticed.
• the present disclosure insightfully recognizes that if the filter permeability condition can be detected while the reductant system is fully operational, maintenance on the reductant system 20 can be scheduled at a convenient time to replace filter 24 before the filter permeability condition becomes so severe that an actual system fault occurs.
• reductant dosing system may be disabled.
• Other fault modes e.g. plugged injector
• a sudden system fault can require that the machine 10 be shut down for immediate and costly maintenance at an unscheduled time disrupting worksite organization and undermining productivity.
• reductant dosing systems may be on some regular maintenance schedule that does or does not take into account the environment in which the machine 10 is operating, detection of a filter permeability condition according to the present disclosure can provide early warning of a forthcoming system fault while the reductant system 20 remains fully operational.
• electronic controller 23 may include a reductant system fault algorithm configured to log a reductant system fault responsive to pressure in fluid circuit 30 of reductant system 20 falling to less than a dosing pressure threshold necessary for proper operation of injector 34.
• the reductant system fault algorithm may be configured to disable the reductant system 20 responsive to the reductant system fault.
• electronic controller 23 may be configured to maintain the reductant system 20 operational responsive to a filter permeability condition.
• the filter status algorithm may be configured to determine a time rate of change in the tank level data communicated by float sensor 22.
• the filter status algorithm may be configured to log a filter permeability condition responsive to the time rate of change in the tank level data being greater than an expected time rate of change while reductant 37 is being dosed from injector 34 into exhaust pipe 17 of engine 15.
• electronic controller 23 should know the reductant dosing rate and can estimate the rate at which the tank level should fall responsive to that dosing rate.
• the fluid level in outlet volume 26 may fall faster than the tank level ought to fall responsive to that dosing rate. This condition, for instance is illustrated in Fig. 4. When this occurs, a filter permeability condition is detected, and the operator may be alerted in a suitable manner so that changing of the sock filter 24 may be added to the next regular servicing agenda of machine 10, in order to avoid
• the present disclosure also contemplates another opportunity for detecting a filter permeability condition. For instance, when the engine is changed to a state, such as a shutdown routine, when reductant dosing is ceased, the filter status algorithm may also be configured to log a filter permeability condition responsive to an increase in the tank level data that is greater than an expected increase threshold, after reductant dosing has ceased and inlet 27 is closed.
• a state such as a shutdown routine
• the filter status algorithm may also be configured to log a filter permeability condition responsive to an increase in the tank level data that is greater than an expected increase threshold, after reductant dosing has ceased and inlet 27 is closed.
• the filter permeability condition prevents the briefly higher fluid level in the outlet volume 26 from passing in a reverse direction through filter 24 to balance with the fluid level in inlet volume 25.
• a filter permeability condition is detected in this manner, the operator may be notified or alerted in a conventional manner, and sock filter replacement may be added to a next servicing agenda for machine 10 by the operator or possibly automatically by electronic controller 23 in a known manner.
• the present disclosure finds potential application in any machine that includes an engine with a reductant dosing system.
• the present disclosure finds specific applicability to machines that must operate in debris and dirt filled environments that increase the likelihood of contaminants finding their way into a reductant tank.
• the present disclosure finds application in any reductant dosing system in which an inlet volume of the tank is separated from an outlet volume by a serviceable filter element.
• reductant dosing algorithm 50 may be executed in conjunction with regular operation of machine 10.
• engine 15 is started and proceeds to run in a conventional manner so that exhaust from engine 15 is moved through exhaust pipe 17.
• electronic controller 23 activates reductant pump 31. This results in reductant 37 circulating around fluid circuit 30 from the outlet volume 26 of reductant tank 21, through pump 31 and into return line 32, which opens back into outlet volume 26.
• the aftertreatment system 16 is warmed up to proper treatment temperatures at box 62.
• electronic controller 23 answers the question of whether the aftertreatment system 16 is warmed up to proper operational temperatures. If not, the logic will loop back and continue to warm up the aftertreatment system at box 62. If affirmative, the logic may advance to box 64 where electronic controller 23 determines a desired dosing rate using other logic outside the scope of this disclosure. For instance, this logic may attempt to set a dosing rate to match the production rate of NOx from engine 15 as discussed earlier.
• the reductant dosing system pressure is measured by pressure sensor 35.
• the reductant tank level data from fluid level sensor 22 is communicated to electronic controller 23.
• the logic determines whether system pressure is too low for proper operation of injector 34.
• system fault algorithm 56 may be substantially more complicated and allow for incrementally derating engine 15 as inducements for the operator to seek servicing prior to completely disabling the reductant dosing system and completely derate engine 15 in order to force the operator to seek servicing of machine 10. If a system fault occurs, the logic ends at oval 84.
• the logic advances to box 68 and reductant is dosed into exhaust pipe 17 of engine 15. This should result in movement of reductant from the inlet volume 25 into the outlet volume 26 through filter 24 in order to make up for the dosed reductant.
• the logic determines a time rate of change in the tank level data originating from float sensor 22.
• the logic asks whether the tank level in outlet volume 26 is dropping faster than expected. For instance, if the dosing rate exceeds the rate at which fluid can pass through filter medium 24, the level in the outlet volume 26 will drop faster than the level in inlet volume 25 resulting in a filter permeability condition schematically illustrated in Fig. 4.
• the filter status algorithm 55 logs a filter permeability condition responsive to the tank level data differing from expected data by greater than some predetermined threshold that avoids false detections that might otherwise occur due to such causes as abrupt machine movements and the like.
• the filter status algorithm 55 may compare tank level data to expected data.
• the logic may advance to query 74 in order to determine whether engine shut down has been initiated.
• engine shutdown may constitute a procedure that lasts several seconds to several minutes in order to properly shut down all of the engine subsystems before actually stopping the engine. If query 74 returns a negative, the logic loops back to again determine the dosing rate at box 64 and repeats the determinations measurements and queries as shown in Fig. 5. If query 74 returns a positive, as part of the engine shut down reductant dosing is ceased at box 75, such as when the engine is placed in an idle condition prior to being completely stopped.
• the filter status algorithm queries whether the tank level in outlet volume 26 is increasing too much due to the evacuation of reductant from fluid circuit 30. This aspect of the logic suggests that the filter status algorithm 23 knows the fluid volume of fluid circuit 30 and the rate by which that fluid will return to tank 21 when the reductant dosing has ceased during a normal engine shut down procedure. If that fluid level in the outlet volume 26 is increasing too much, the query will move to box 77 and log a filter permeability condition because that circumstance indicates that fluid is having difficulty moving from the outlet volume 26 into the inlet volume 25 due to degraded permeability in filter 24. At box 78, the operator may be alerted and at box 79 the sock filter change may be added to the next servicing agenda for machine 10. If query 76 returns a negative, the logic advance to oval 80 to end indicating that a proper engine shut down.
• the abbreviated version of a reductant system fault algorithm 56 is included in the reductant dosing algorithm 50 to contrast a system fault from a system condition.
• a system fault if ignored, will eventually result in disabling the reductant dosing system 20.
• detection of a filter permeability condition is treated differently in that electronic controller may maintain the reductance dosing system operational responsive to a filter permeability condition.
• the screen filter 39 and the fine particulate filter 33 are identified in order to contrast those known system filters with the added sock filter and filter status algorithm of the present disclosure.
• pump 31 pumps reductant through filter 33, but gravity may be responsible for movement of reductant fluid between inlet volume 25 and outlet volume 26 through sock filter 24.
• the expected time rate of change in the tank level data may be based upon the known dosing rate commanded during normal system operation and an understanding of the fluid surface area in tank 21.
• the teachings of the present disclosure may be useful in proactively planning for proper servicing of the reductant dosing system 20 prior to an otherwise inevitable fault requiring the potential disablement of the reductant system and associated taking of machine 10 offline.
• Replacement of a sock filter according to the present disclosure can be accomplished by detaching the head 29 from tank 21, loosening clamp 36 and then sliding sock filter 24 free of head 29. A new sock filter 24 can then be replaced in a reverse manner. While this is being performed, the technician may utilize the opportunity to inspect and/or service other aspects of the reductant dosing system 20 in an effort to maintain machine 10's productivity and avoid untimely reductant system faults.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Exhaust Gas After Treatment (AREA)

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• 2014
  • 2014-02-03 US US14/170,857 patent/US20150218990A1/en not_active Abandoned
• 2015
  • 2015-02-03 WO PCT/US2015/014204 patent/WO2015117114A1/en active Application Filing
  • 2015-02-03 DE DE112015000334.7T patent/DE112015000334T5/de active Pending
  • 2015-02-03 CN CN201580006695.7A patent/CN105940197B/zh active Active

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