US20140373508A1 - Reductant delivery unit for automotive selective catalytic reduction with thermally optimized peak-and-hold actuation based on an injector open event - Google Patents
Reductant delivery unit for automotive selective catalytic reduction with thermally optimized peak-and-hold actuation based on an injector open event Download PDFInfo
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- US20140373508A1 US20140373508A1 US13/921,231 US201313921231A US2014373508A1 US 20140373508 A1 US20140373508 A1 US 20140373508A1 US 201313921231 A US201313921231 A US 201313921231A US 2014373508 A1 US2014373508 A1 US 2014373508A1
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- Prior art keywords
- injector
- peak
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- trigger
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Classifications
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- 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
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- 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]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
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- 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
- F01N3/206—Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents
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- 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
- F01N3/24—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 constructional aspects of converting apparatus
- F01N3/36—Arrangements for supply of additional fuel
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- 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
- F01N9/00—Electrical control of exhaust gas treating apparatus
-
- 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
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- 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
- F01N2900/1821—Injector parameters
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/18—Modifications for indicating state of switch
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/28—Modifications for introducing a time delay before switching
- H03K17/284—Modifications for introducing a time delay before switching in field effect transistor switches
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- 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- 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
Definitions
- the invention relates to a reductant delivery unit (RDU) that supplies reducing agent to an engine exhaust system and, more particularly, to an RDU that improves on the overall electrical loading over a wide temperature range by triggering the transition from peak to hold based on the detection of injector opening.
- RDU reductant delivery unit
- Ammonia is difficult to handle in its pure form in the automotive environment. Therefore, it is customary with these systems to use a liquid aqueous urea solution, typically at a 32% concentration of urea solution (CO (NH 2 ) 2 ).
- the solution is referred to as AUS-32, and is also known under its commercial name of AdBlue.
- the urea solution is delivered to the hot exhaust stream and is transformed into ammonia in the exhaust after undergoing thermolysis, or thermal decomposition, into ammonia and isocyanic acid (HNCO).
- HNCO isocyanic acid
- the isocyanic acid then undergoes a hydrolysis with the water present in the exhaust and is transformed into ammonia and carbon dioxide (CO2).
- CO2 ammonia resulting from the thermolysis and the hydrolysis then undergoes a catalyzed reaction with the nitrogen oxides as described previously.
- the AUS-32 injector is typically installed directly on the engine exhaust, which exposes it to a very hot environment.
- peak-and-hold injector drivers have been implemented. With reference to FIG. 1 , the function of this driver is to actuate the injector in two modes describing the injector current: a rise-to-peak current phase, followed by a low current hold phase (current control at high switching frequency).
- the low current level is typically at a value that is much lower than the full saturated current level of the injector, and higher than the minimum level of current needed to maintain the injector (solenoid) open.
- the transition from the rise to peak to the hold phase is usually triggered by a current level detection on the current; once the current reaches that level, the subsequent hold phase is enabled.
- FIG. 2 shows a peak-and-hold circuit 10 having a conventional peak current detection and trigger circuit 12 .
- the main advantage to operating the injector with a low hold phase is the lower electrical load that results compared to operation under saturated switch conditions.
- An injector that is operated with a 0.5 A hold mode will dissipate 7 Watts during the hold phase.
- the peak current is specified at a level of 0.8 A. This is above the required nominal opening current of 0.6 A.
- the specified nominal hold current is 0.5 A.
- a situation could arise where the saturated injector current is 0.7 A, for example, if the available electrical supply voltage is only 12V, but the injector coil resistance is 17 ⁇ , (e.g., the injector coil temperature is 130 C).
- An illustration of what the current waveform would look like in this case is shown in FIG. 3 .
- the risk of this condition is then to have an injector operating already at an elevated temperature that is subjected to an increased electrical thermal load.
- a trigger circuit for a peak and hold driver circuit for a reductant delivery unit (RDU) having a solenoid-operated injector for selective catalytic reduction (SCR) after-treatment for vehicles is constructed and arranged to actuate the injector in a rise-to-peak current phase followed by a low current hold phase.
- the trigger circuit includes an injector open detection circuit constructed and arranged, based on a detected opening event of the injector, to trigger a transition from the rise-to-peak phase to the subsequent hold phase of the injector.
- a reductant delivery unit (RDU) and control unit for selective catalytic reduction (SCR) after-treatment for vehicles includes an RDU having a solenoid-operated injector.
- a control unit is electrically connected with the solenoid.
- the control unit has a peak and hold driver circuit constructed and arranged to actuate the injector in a rise-to-peak current phase followed by a low current hold phase.
- the driver circuit includes an injector open detection circuit constructed and arranged, based on a detected opening event of the injector, to trigger a transition from the rise-to-peak phase to the subsequent hold phase of the injector.
- a method of triggering a reductant delivery unit (RDU) having a solenoid-operated injector for selective catalytic reduction (SCR) after-treatment for vehicles detects an opening event of the injector, and based on the detecting, step, triggers a transition from a rise-to-peak phase to a subsequent hold phase of the injector, thereby limiting a thermal load on the injector to a minimum required to ensure opening of the injector.
- RDU reductant delivery unit
- SCR selective catalytic reduction
- FIG. 1 is view of conventional injector current, showing rise-to-peak phase followed by a low current hold phase.
- FIG. 2 is a block diagram of a conventional peak-and-hold circuit with a peak current detection and trigger circuit.
- FIG. 3 is view of a conventional current waveform showing saturation current at 0.7 A.
- FIG. 4 shows conventional opening event detection of an injector by current analysis.
- FIG. 5 shows detection of opening time from second derivative of coil current.
- FIG. 6 is a peak-and-hold circuit block diagram with an injector open detection circuit provided in accordance with an embodiment.
- FIG. 7 shows a current waveform that results from the circuit of FIG. 6 .
- FIG. 8 is a view of a control unit containing the circuits of FIG. 6 for operating an RDU.
- the disclosed embodiment relates to a control strategy to eliminate the risk of an undesirable increase in the thermal load of an injector of an RDU at already elevated operating temperatures.
- the detection of injector opening and closing events by analysis of the voltage or current is well known.
- An example of an opening event detection by current analysis (indicated by “OPP 2 ”) is shown in FIG. 4 , where the accelerometer signal is 14 , the voltage signal is 16 , the test pulse is 18 , and the current signal is 20 .
- one embodiment of such detection is in hardware form with a circuit that generates an electrical pulse 22 upon the opening detection using the second derivative 24 of the current waveform as an input.
- the spurious initial pulse 26 can be ignored by appropriate use of enable windows, e.g., only allowing the pulse through during certain pre-determined times during the injector pulse-width.
- FIG. 6 a block diagram is shown of a peak-and-hold driver circuit 10 ′ constructed and arranged to actuate an injector in a rise-to-peak current phase followed by a low current hold phase in accordance with an embodiment.
- the circuit 10 ′ includes a trigger circuit 28 having an injector open detection circuit 29 .
- the trigger circuit 28 replaces the prior art current threshold trigger circuit 12 of FIG. 2 .
- the circuit 10 ′ uses the injector opening event, as detected, for example, by use of the second derivative 24 of the current waveform noted above, to trigger the transition from the rise-to-peak phase to the subsequent hold phase of the injector actuation control.
- the detection circuit 29 includes a processing or differentiating circuit 31 for differentiating current. Other conventional methods of detecting an opening state of an actuator or injector can be used instead of using the second derivative of current.
- An illustration of the current waveform 30 that would result from implementation of the embodiment is shown in FIG. 7 .
- the circuit 10 ′ including the trigger circuit 28 is preferably provided in a control unit 32 that is electrically connected to a solenoid operated injector 34 of an RDU, generally indicated at 36 .
- the RDU 36 can be employed in a system of the type disclosed in U.S. Patent Application Publication No. 2008/0236147 A1, the contents of which is hereby incorporated by reference into this specification.
- the RDU 36 includes the solenoid fluid injector 34 that provides a metering function of fluid and provides the spray preparation of the fluid into the exhaust gas flow path of a vehicle in a dosing application.
- the fluid injector 34 is preferably a gasoline, electrically operated, solenoid (coil) fuel injector such as the type disclosed in U.S. Pat. No. 6,685,112, the content of which is hereby incorporated by reference into this specification.
- solenoid (coil) fuel injector such as the type disclosed in U.S. Pat. No. 6,685,112, the content of which is hereby incorporated by reference into this specification.
- the thermal loading of the injector is thereby limited to the minimum required to ensure opening of the injector. The risk of a drawn-out rise-to-peak phase and therefore additional thermal loading is also avoided.
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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)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
A trigger circuit is provided for a peak and hold driver circuit for a reductant delivery unit (RDU) having a solenoid-operated injector for selective catalytic reduction (SCR) after-treatment for vehicles. The peak and hold driver circuit is constructed and arranged to actuate the injector in a rise-to-peak current phase followed by a low current hold phase. The trigger circuit includes an injector open detection circuit constructed and arranged, based on a detected opening event of the injector, to trigger a transition from the rise-to-peak phase to the subsequent hold phase of the injector.
Description
- The invention relates to a reductant delivery unit (RDU) that supplies reducing agent to an engine exhaust system and, more particularly, to an RDU that improves on the overall electrical loading over a wide temperature range by triggering the transition from peak to hold based on the detection of injector opening.
- The advent of a new round of stringent emissions legislation in Europe and North America is driving the implementation of new exhaust after-treatment systems, particularly for lean-burn technologies such as compression-ignition (diesel) engines, and stratified-charge spark-ignited engines (usually with direct injection) that are operating under lean and ultra-lean conditions. Lean-burn engines exhibit high levels of nitrogen oxide (NOx) emissions that are difficult to treat in oxygen-rich exhaust environments characteristic of lean-burn combustion. Exhaust after-treatment technologies are currently being developed that will treat NOx under these conditions. One of these technologies comprises a catalyst that facilitates the reactions of ammonia (NH3) with the exhaust nitrogen oxides (NOx) to produce nitrogen (N2) and water (H2O). This technology is referred to as Selective Catalytic Reduction (SCR).
- Ammonia is difficult to handle in its pure form in the automotive environment. Therefore, it is customary with these systems to use a liquid aqueous urea solution, typically at a 32% concentration of urea solution (CO (NH2)2). The solution is referred to as AUS-32, and is also known under its commercial name of AdBlue. The urea solution is delivered to the hot exhaust stream and is transformed into ammonia in the exhaust after undergoing thermolysis, or thermal decomposition, into ammonia and isocyanic acid (HNCO). The isocyanic acid then undergoes a hydrolysis with the water present in the exhaust and is transformed into ammonia and carbon dioxide (CO2). The ammonia resulting from the thermolysis and the hydrolysis then undergoes a catalyzed reaction with the nitrogen oxides as described previously.
- The AUS-32 injector is typically installed directly on the engine exhaust, which exposes it to a very hot environment. In order to reduce the electrical thermal loading of the injector, so-called peak-and-hold injector drivers have been implemented. With reference to
FIG. 1 , the function of this driver is to actuate the injector in two modes describing the injector current: a rise-to-peak current phase, followed by a low current hold phase (current control at high switching frequency). - The low current level is typically at a value that is much lower than the full saturated current level of the injector, and higher than the minimum level of current needed to maintain the injector (solenoid) open. In today's driver circuits, the transition from the rise to peak to the hold phase is usually triggered by a current level detection on the current; once the current reaches that level, the subsequent hold phase is enabled.
FIG. 2 shows a peak-and-hold circuit 10 having a conventional peak current detection andtrigger circuit 12. - The main advantage to operating the injector with a low hold phase is the lower electrical load that results compared to operation under saturated switch conditions. For example, an injector with a 12-ohm coil, supplied by 14V, will dissipate 16.3 Watts (I=1.2 A). An injector that is operated with a 0.5 A hold mode will dissipate 7 Watts during the hold phase.
- A disadvantage arises as the temperature increases and the injector resistance increases. As the resistance increases, the time required for the current to reach a given threshold will increase due to the dependence of the time on the coil resistance. In a limiting case with a sufficiently high temperature, the current may never reach the transition threshold, and yet the injector is open. The temperature range where this would occur is dependent on the difference between the selected transition current level and the minimum current required to open the injector. This difference will be non-zero to take into account tolerances and variations of the various elements that make up the electrical and magnetic circuits.
- As an example, today the peak current is specified at a level of 0.8 A. This is above the required nominal opening current of 0.6 A. The specified nominal hold current is 0.5 A. A situation could arise where the saturated injector current is 0.7 A, for example, if the available electrical supply voltage is only 12V, but the injector coil resistance is 17Ω, (e.g., the injector coil temperature is 130 C). An illustration of what the current waveform would look like in this case is shown in
FIG. 3 . The risk of this condition is then to have an injector operating already at an elevated temperature that is subjected to an increased electrical thermal load. - Thus, there is a need for an RDU that improves on the overall electrical loading over a wide temperature range by triggering the transition from peak to hold based on the detection of injector opening.
- An object of the invention is to fulfill the needs referred to above. In accordance with the principles of the present invention, this objective is obtained by a trigger circuit for a peak and hold driver circuit for a reductant delivery unit (RDU) having a solenoid-operated injector for selective catalytic reduction (SCR) after-treatment for vehicles. The peak and hold driver circuit is constructed and arranged to actuate the injector in a rise-to-peak current phase followed by a low current hold phase. The trigger circuit includes an injector open detection circuit constructed and arranged, based on a detected opening event of the injector, to trigger a transition from the rise-to-peak phase to the subsequent hold phase of the injector.
- In accordance with another aspect of an embodiment, a reductant delivery unit (RDU) and control unit for selective catalytic reduction (SCR) after-treatment for vehicles includes an RDU having a solenoid-operated injector. A control unit is electrically connected with the solenoid. The control unit has a peak and hold driver circuit constructed and arranged to actuate the injector in a rise-to-peak current phase followed by a low current hold phase. The driver circuit includes an injector open detection circuit constructed and arranged, based on a detected opening event of the injector, to trigger a transition from the rise-to-peak phase to the subsequent hold phase of the injector.
- In accordance with yet another aspect of an embodiment, a method of triggering a reductant delivery unit (RDU) having a solenoid-operated injector for selective catalytic reduction (SCR) after-treatment for vehicles detects an opening event of the injector, and based on the detecting, step, triggers a transition from a rise-to-peak phase to a subsequent hold phase of the injector, thereby limiting a thermal load on the injector to a minimum required to ensure opening of the injector.
- Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
- The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:
-
FIG. 1 is view of conventional injector current, showing rise-to-peak phase followed by a low current hold phase. -
FIG. 2 is a block diagram of a conventional peak-and-hold circuit with a peak current detection and trigger circuit. -
FIG. 3 is view of a conventional current waveform showing saturation current at 0.7 A. -
FIG. 4 shows conventional opening event detection of an injector by current analysis. -
FIG. 5 shows detection of opening time from second derivative of coil current. -
FIG. 6 is a peak-and-hold circuit block diagram with an injector open detection circuit provided in accordance with an embodiment. -
FIG. 7 shows a current waveform that results from the circuit ofFIG. 6 . -
FIG. 8 is a view of a control unit containing the circuits ofFIG. 6 for operating an RDU. - The disclosed embodiment relates to a control strategy to eliminate the risk of an undesirable increase in the thermal load of an injector of an RDU at already elevated operating temperatures. The detection of injector opening and closing events by analysis of the voltage or current is well known. An example of an opening event detection by current analysis (indicated by “OPP2”) is shown in
FIG. 4 , where the accelerometer signal is 14, the voltage signal is 16, the test pulse is 18, and the current signal is 20. - The detection of these events is useful for diagnostics purposes, and can also be used to compensate for lifetime shifts in flow due to changes in the duration of the injector transient phase. With reference to
FIG. 5 , one embodiment of such detection is in hardware form with a circuit that generates anelectrical pulse 22 upon the opening detection using thesecond derivative 24 of the current waveform as an input. The spuriousinitial pulse 26 can be ignored by appropriate use of enable windows, e.g., only allowing the pulse through during certain pre-determined times during the injector pulse-width. An example of using the second derivative of current in detecting a state of an injector is disclosed in co-pending, U.S. Provisional Application, filed on the same date as this regular application, entitled, “Solenoid-Actuator-Armature End-of-Motion Detection, Attorney Docket Number: 2012P02238US, the contents of which is hereby incorporated by reference into this specification. - With reference to
FIG. 6 , a block diagram is shown of a peak-and-hold driver circuit 10′ constructed and arranged to actuate an injector in a rise-to-peak current phase followed by a low current hold phase in accordance with an embodiment. Thecircuit 10′ includes atrigger circuit 28 having an injectoropen detection circuit 29. Thus, thetrigger circuit 28 replaces the prior art currentthreshold trigger circuit 12 ofFIG. 2 . Thecircuit 10′ uses the injector opening event, as detected, for example, by use of thesecond derivative 24 of the current waveform noted above, to trigger the transition from the rise-to-peak phase to the subsequent hold phase of the injector actuation control. In the embodiment, thedetection circuit 29 includes a processing or differentiatingcircuit 31 for differentiating current. Other conventional methods of detecting an opening state of an actuator or injector can be used instead of using the second derivative of current. An illustration of thecurrent waveform 30 that would result from implementation of the embodiment is shown inFIG. 7 . - With reference to
FIG. 8 , thecircuit 10′ including thetrigger circuit 28 is preferably provided in acontrol unit 32 that is electrically connected to a solenoid operatedinjector 34 of an RDU, generally indicated at 36. TheRDU 36 can be employed in a system of the type disclosed in U.S. Patent Application Publication No. 2008/0236147 A1, the contents of which is hereby incorporated by reference into this specification. - The
RDU 36 includes thesolenoid fluid injector 34 that provides a metering function of fluid and provides the spray preparation of the fluid into the exhaust gas flow path of a vehicle in a dosing application. Thefluid injector 34 is preferably a gasoline, electrically operated, solenoid (coil) fuel injector such as the type disclosed in U.S. Pat. No. 6,685,112, the content of which is hereby incorporated by reference into this specification. Thus, when the coil of theinjector 34 is energized, a valve in the injector opens, causing reductant to be delivered to an exhaust flow path in the conventional manner. - By using the injector opening event as a trigger, the thermal loading of the injector is thereby limited to the minimum required to ensure opening of the injector. The risk of a drawn-out rise-to-peak phase and therefore additional thermal loading is also avoided.
- The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.
Claims (11)
1. A trigger circuit for a peak and hold driver circuit for a reductant delivery unit (RDU) having a solenoid-operated injector for selective catalytic reduction (SCR) after-treatment for vehicles, the peak and hold driver circuit being constructed and arranged to actuate the injector in a rise-to-peak current phase followed by a low current hold phase, the trigger circuit comprising:
an injector open detection circuit constructed and arranged, based on a detected opening event of the injector, to trigger a transition from the rise-to-peak phase to the subsequent hold phase of the injector.
2. The trigger circuit of claim 1 , in combination with the driver circuit so that the driver circuit includes the trigger circuit.
3. The combination of claim 2 , in further combination with the RDU.
4. The combination of claim 3 , wherein the driver circuit and trigger circuit are part of a control unit electrically connected with the RDU.
5. The trigger circuit of claim 1 , wherein the open detection circuit is constructed and arranged to trigger the transition based on an electrical pulse generated upon detecting the opening event of the injector by using a second derivative of a current waveform as an input.
6. The trigger circuit of claim 5 , wherein the open detection circuit includes a differentiating circuit.
7. A reductant delivery unit (RDU) and control unit for selective catalytic reduction (SCR) after-treatment for vehicles, the RDU and control unit comprising:
an RDU having a solenoid-operated injector, and
a control unit electrically connected with the injector, the control unit having a peak and hold driver circuit constructed and arranged to actuate the injector in a rise-to-peak current phase followed by a low current hold phase, the driver circuit including an injector open detection circuit constructed and arranged, based on a detected opening event of the injector, to trigger a transition from the rise-to-peak phase to the subsequent hold phase of the injector.
8. The RDU and control unit of claim 7 , wherein the injector open detection circuit is constructed and arranged to trigger the transition based on an electrical pulse generated upon detecting the opening event of the injector by using a second derivative of a current waveform as an input
9. The RDU and control unit of claim 8 , wherein the injector open detection circuit includes a differentiating circuit.
10. A method of triggering a reductant delivery unit (RDU) having a solenoid-operated injector for selective catalytic reduction (SCR) after-treatment for vehicles, the method comprising:
detecting an opening event of the injector, and
based on the detecting, step, triggering a transition from a rise-to-peak phase to a subsequent hold phase of the injector, thereby limiting a thermal load on the injector to a minimum required to ensure opening of the injector.
11. The method of claim 10 , wherein the detecting step uses a second derivative of a current waveform of the injector.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/921,231 US20140373508A1 (en) | 2013-06-19 | 2013-06-19 | Reductant delivery unit for automotive selective catalytic reduction with thermally optimized peak-and-hold actuation based on an injector open event |
DE201410209575 DE102014209575A1 (en) | 2013-06-19 | 2014-05-20 | Reducing agent supply unit for selective catalytic reduction for a vehicle with thermally optimized maximum value hold operation based on the opening of an injector |
JP2014125547A JP5859067B2 (en) | 2013-06-19 | 2014-06-18 | Reductant delivery unit for selective catalytic reduction for vehicles with thermally optimized peak and hold action based on injector opening event |
CN201410275526.0A CN104358605B (en) | 2013-06-19 | 2014-06-19 | The reducing agent supply unit for selective catalytic reduction for thering is peak holding to activate |
KR1020140074925A KR101598431B1 (en) | 2013-06-19 | 2014-06-19 | Reductant delivery unit for automotive selective catalytic reduction with thermally optimized peak-and-hold actuation based on an injector open event |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/921,231 US20140373508A1 (en) | 2013-06-19 | 2013-06-19 | Reductant delivery unit for automotive selective catalytic reduction with thermally optimized peak-and-hold actuation based on an injector open event |
Publications (1)
Publication Number | Publication Date |
---|---|
US20140373508A1 true US20140373508A1 (en) | 2014-12-25 |
Family
ID=52010601
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/921,231 Abandoned US20140373508A1 (en) | 2013-06-19 | 2013-06-19 | Reductant delivery unit for automotive selective catalytic reduction with thermally optimized peak-and-hold actuation based on an injector open event |
Country Status (5)
Country | Link |
---|---|
US (1) | US20140373508A1 (en) |
JP (1) | JP5859067B2 (en) |
KR (1) | KR101598431B1 (en) |
CN (1) | CN104358605B (en) |
DE (1) | DE102014209575A1 (en) |
Cited By (3)
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US20150275812A1 (en) * | 2012-10-15 | 2015-10-01 | Denso Corporation | Fuel supply device |
WO2019177521A1 (en) * | 2018-03-15 | 2019-09-19 | Scania Cv Ab | System and method for controlling operation of a dosing unit of a fluid dosing system |
US11391190B2 (en) * | 2020-03-20 | 2022-07-19 | Southwest Research Institute | Combined catalyst precursor/surfactant mixture for reductant urea solution for selective catalytic reduction |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
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JP6655172B2 (en) * | 2015-09-24 | 2020-02-26 | ロベルト・ボッシュ・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツングRobert Bosch Gmbh | System and method for enhancing diesel exhaust fluid delivery capacity |
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JP3458730B2 (en) * | 1998-11-10 | 2003-10-20 | 国産電機株式会社 | Method and apparatus for driving injector for internal combustion engine |
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- 2014-05-20 DE DE201410209575 patent/DE102014209575A1/en active Pending
- 2014-06-18 JP JP2014125547A patent/JP5859067B2/en active Active
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US11391190B2 (en) * | 2020-03-20 | 2022-07-19 | Southwest Research Institute | Combined catalyst precursor/surfactant mixture for reductant urea solution for selective catalytic reduction |
Also Published As
Publication number | Publication date |
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CN104358605A (en) | 2015-02-18 |
KR20140147745A (en) | 2014-12-30 |
JP5859067B2 (en) | 2016-02-10 |
KR101598431B1 (en) | 2016-02-29 |
CN104358605B (en) | 2019-01-01 |
JP2015004360A (en) | 2015-01-08 |
DE102014209575A1 (en) | 2014-12-24 |
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