APPARATUS AND METHOD FOR DIAGNOSING A NOx SENSOR

专利摘要:
apparatus and method for diagnosing a nox ensor. one method includes raising a temperature of a catalyst scr for a predetermined period of time while dosing urea. the method further includes maintaining the temperature of the catalyst scr without dosing urea for a second predetermined period of time. the method further includes filtering at least low frequency data from a first nox sensor upstream of the scr catalyst, and purchasing the filtered data from the first nox sensor and the second nox sensor without dosing urea over a third period of time predetermined. the method further includes providing a sensor condition index for at least one between the first nox sensor and the second nox sensor in response to the comparison.
公开号:BR112012014974B1
申请号:R112012014974-1
申请日:2010-12-16
公开日:2020-02-18
发明作者:Xiao Lin；Daniel W. Wilhelm；Baohua Qi；Xi Wei
申请人:Cummins Filtration Ip, Inc.；
IPC主号:

专利说明:

“APPARATUS AND METHOD FOR DIAGNOSING A NOx SENSOR” RELATED REQUESTS [0001] This order relates to and claims the benefit of provisional order US 61 / 286,958 entitled APPARATUS AND METHOD TO DIAGNOSIS NOx SENSOR, filed on December 16, 2009, which is incorporated into this document by reference.
BACKGROUND [0002] The technical field refers in general to diagnosing a NOx sensor, and more particularly, but not exclusively, to detecting a difference in response between two Nox sensors on each side of a catalyst with ammonia storage capacity . Modern internal combustion engines often use aftertreatment systems to achieve regulatory emissions targets. An after-treatment system is a NOx reduction device, including a catalyst for a selective catalytic reduction (SCR) system. It is useful for controls, and in some cases, it is prescribed by regulation that a defective Nox sensor or under non-nominal operating conditions is detected, allowing the control scheme to use an alternative NOx determination and / or to establish an mistake. NOx sensors that are commercially viable for use in the field with an internal combustion engine have an interference with ammonia (NH3), erroneously detecting a significant percentage (80% or greater) of NH3 as NOx. In addition, reactions with the device NOx reduction causes a difference from NOx at the input to NOx at the output that is not attributable to the sensors.
[0003] Therefore, simply comparing sensor signals during motor operations will generally not allow determining a faulty sensor or under non-rated operating conditions. Therefore, other technological developments are desirable in this area.
SUMMARY [0004] A modality is a unique method for diagnosing errors in a
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2/23 NOx sensor. Other modalities, shapes, objects, characteristics, advantages, aspects and benefits will become apparent from the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS [0005] Fig. 1 is a schematic diagram of a system for diagnosing a NOx sensor.
[0006] FIG. 2 is a block diagram of a controller that diagnoses a NOx sensor.
[0007] FIG. 3 is an illustration of raw NOx sensor outputs.
[0008] FIG. 4 is an illustration of filtered bandpass NOx sensor outputs.
[0009] FIG. 5 is an illustration of frequency domain NOx sensor outputs.
[0010] FIG. 6 is an illustration of an engine NOx output and urea dosing timeline.
[0011] FIG. 7 is an illustration of a diagnostic procedure.
[0012] FIG. 8 is a schematic flow chart of a diagnostic procedure.
[0013] FIG. 9 is an illustration of a data processing operation for NOx sensor data.
DESCRIPTION OF ILLUSTRATIVE MODALITIES [0014] In order to promote an understanding of the principles of the invention, reference will now be made to the modalities illustrated in the drawings, and a specific language will be used to describe them. However, it will be understood that it is therefore not intended to limit the scope of the invention in any way, any changes and other modifications to the illustrated modalities, and any other applications of the principles of the invention, as illustrated in this document, as would normally occur for a person versed in the art to which the invention refers, are contemplated in this document.
[0015] FIG. 1 is a block diagram of an example system 100 for diagnosing a NOx sensor. System 100 includes a combustion engine
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3/23 internal 102 producing an exhaust gas stream having certain emissions treated by an aftertreatment component 104 and / or an SCR catalyst 106. System 100 includes a temperature determination of the SCR catalyst, which may include one or more 113 temperature sensors and / or temperature models. The temperature sensor 113 is indicated in an intermediate bed of the SCR 106 catalyst, but the temperature sensor 113 can also be upstream and / or downstream of the SCR 106 catalyst. The SCR 106 catalyst can also be modeled, in certain modalities, for example, from an upstream temperature in the exhaust stream.
[0016] System 100 also includes a reducer storage 116 that supplies reducer to a reducer injector 118. Reducer injector 118 adds reducer to the exhaust stream in a position upstream of the SCR 106 catalyst. The reducer includes urea and / or ammonia, and the SCR 106 catalyst has some ammonia storage capacity. The magnitude of the ammonia storage capacity of the SCR 106 catalyst is a function of the temperature of the SCR 106 catalyst. It is known in the art that generally a lower temperature of the SCR 106 catalyst increases the ammonia storage capacity of the SCR 106 catalyst.
[0017] System 100 also includes a first NOx 108 sensor upstream of the SCR 106 catalyst and a second NOx 110 sensor downstream of the SCR 106 catalyst. The first NOx 108 sensor is illustrated in a downstream position of the injector. reducer 118, but the first NOx sensor 108 can be positioned anywhere in the exhaust stream that is upstream of the SCR catalyst 106 and downstream of the internal combustion engine 102. In certain embodiments, injected urea hydrolyzes to ammonia in the exhaust, and the first NOx 108 sensor reads the ammonia at least partially as NOx. Therefore, the first NOx 108 sensor can be positioned in a place within the exhaust stream where, so far, urea is not expected will hydrolyse to ammonia detectable in the gas phase, for example, in a position close to the reducer injector 118, or the first NOx sensor 108 can be positioned upstream
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4/23 of the reducer injector 118. In certain embodiments, the first NOx 108 sensor can be positioned where a portion or all of the injected reducer is expected to hydrolyze into ammonia, and the effect of the ammonia amount is estimated and subtracted from the NOx level indicated on the first NOx sensor. In certain embodiments, the first NOx 108 sensor is not sensitive to ammonia in the exhaust stream.
[0018] System 100 may also include hardware, which is not shown in fig. 1, but which is nevertheless included in this document. Specifically, and without limitation, in certain embodiments the system includes an oxidation catalyst, a turbocharger, an exhaust gas recirculation (EGR) cycle, a hydrocarbon injector in an upstream position of the oxidation catalyst and / or component post-treatment, a common channel fuel system of the internal combustion engine capable of releasing unburned hydrocarbons or heat from very late combustion in the exhaust stream. The addition or replacement of one or more of the described hardware is well known in the art, and this hardware will not be described further, except in cases where specific operations or procedures in this document use this hardware.
[0019] System 100 includes a diagnostic output 114 that receives certain information or commands from a controller 112. The diagnostic output 114 can be a hardware device (for example, a malfunction indicator lamp), a controller (separate from or combined with controller 112 described in this document, for example, a motor, transmission or after-treatment controller), a data link (for example, receiving published diagnostic data for self-diagnosis (OBD) purposes), or any other device known in the art.
[0020] The system includes controller 112 that performs certain operations to diagnose a NOx sensor 108, 110. In certain embodiments, controller 112 forms a portion of a processing subsystem, including one or more computing devices having memory hardware , processing and communication. Controller 112 can be a simple device or a device
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5/23 distributed, and the functions of controller 112 can be performed by hardware or software. Controller 112 communicates with any sensor, actuator or system component 110 to perform the operations described in this document. Communication can be direct, electronic, by wire, wirelessly, over a network, and / or over a data link. Controller 112 can be part of or in communication with a motor controller (not shown), and can determine engine operating parameters from the motor controller.
[0021] In certain embodiments, controller 112 includes one or more modules structured to perform the controller operations functionally. In certain embodiments, the controller includes a regeneration event module, a diagnostic staging module, a sensor phasing module, a sensor filtering module, an SCR diagnostic module, and / or a reducer dosing module . The regeneration event module determines whether a post-treatment component regeneration event has occurred and is complete. The diagnostic staging module guides the controller operations through three stages of a diagnostic procedure, and further controls pause, delay, abortion and / or continuation of the diagnostic procedure. The sensor phasing module corrects a time difference in a differential flow element of the exhaust gas flow through the first NOx 108 sensor and the second NOx 110 sensor. The sensor filter module filters the signals from the sensor. NOx filtering at least low frequency information from NOx sensor signals, and in certain modalities by means of bandpass filtering of NOx sensor signals. The SCR diagnostic module compares the filtered sensor data of each between the first sensor NOx and the second NOx sensor, and provides a sensor condition index in response to the compared values. The reducer dosing module provides a reducer dosing command, and reducer injector 118 is sensitive to reducer dosing command 242.
[0022] The description of this document that includes modules emphasizes the structural independence of aspects of controller 112, and illustrates a grouping
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6/23 of operations and responsibilities of the controller 112. Other groupings that perform similar general operations are included within the scope of this order. The modules can be implemented in hardware and / or software in a computer-readable medium, and the modules can be distributed through various hardware or software components. More specific descriptions of certain modes of controller operations are included in the section referenced in fig. 2.
[0023] FIG. 2 is a block diagram of a controller 112 that diagnoses a NOx sensor 108, 110. Controller 112 includes a regeneration event module 202, a diagnostic staging module 204, a sensor phasing module 206, a module filter filter 212, and / or a reducer dosing module 210. The modules described are examples, and certain modes of controller 112 may omit one or more modules.
[0024] The regeneration event module 202 determines whether a post-treatment component regeneration event has occurred and whether it is completed (for example, determining that the AFT COMP REGEN COMPLETE 214 parameter is TRUE). Any regeneration event that includes an extended period of elevated SCR catalyst temperature, such as a temperature-based regeneration of a DPF, can be used here to determine whether the aftertreatment component regeneration event has occurred and whether it is complete .
[0025] Controller 112 also includes a diagnostic staging module 204. The diagnostic staging module guides the operations of controller 112 through three stages of a diagnostic procedure, and other pause, delay, abortion and / or controls continuation of the diagnostic procedure. The diagnostic staging module 204 uses any combination of sensors and actuators known in the art to perform the described operations, including at least providing commands to engine 102, a hydrocarbon injector, a turbocharger, a common channel fuel injection system, or any other hardware. In certain embodiments, in response to the regeneration event module 202 determine the completion of the post regeneration event
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7/23 treatment, the diagnostic staging module 204 maintains the temperature of the SCR 216 catalyst for a predetermined period of time. The temperature maintained is a diagnostic temperature target 228, which can be a temperature selected to allow storage of negligible NH3 in the SCR 106 catalyst - or a storage temperature of negligible NH3 230. In certain catalyst formulations, a temperature of 500 ° C is known to provide very low NH3 storage in the SCR catalyst. However, lower or higher temperature targets can be used for specific catalyst formulations, as will be understood by a person skilled in the art who contemplates a particular catalyst for a particular modality of the system. The predetermined time period 220 is a time period selected for conducting NH3 storage in the SCR catalyst at a low level, or an NH3 storage reduction time.
[0026] At the conclusion of the predetermined time period 220, the diagnostic staging module 204 continues to maintain the temperature in the SCR catalyst at the diagnostic temperature target 228, and controls a reducer dosing module 210 (which provides a control command) reducer dosing 242) to interrupt reducer dosing (for example, urea or NH3) for a second predetermined period of time 222. The diagnostic stage module 204 can determine whether an amount of NOx outside the engine is compatible with interrupting the injection of reducer, and can delay the interruption of the reducer injection and / or exit the diagnostic procedure if the amount of Nox outside the engine is too high. The diagnostic staging module 204 can further estimate the time to complete the diagnostic procedure that will be required under the present conditions, determine a release amount of NOx emissions according to the time to complete the diagnostic procedure, and determine whether to proceed com, waits to perform, or aborts the diagnostic procedure in response to the amount of Nox release emissions that are expected to occur to complete the entire diagnostic procedure.
[0027] At the conclusion of the second predetermined period of time 222, the
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8/23 diagnostic stage module 204 continues to maintain the SCR catalyst temperature 216 at the diagnostic temperature target 228, and continues to command reducer dosing module 210 to interrupt dosing. The diagnostic stage module 204 continues these operations for a third predetermined period of time 224. During the third predetermined period of time 224, sensor filter module 212 filters NOx sensor readings 218 from the first NOx sensor 108 and the second NOx 110 sensor with a high pass filter or a band pass filter 238, and / or sequential high and low pass filters (in either order). The sensor filter module 212 provides filtered NOx sensor readings 240 for other controller modules 112.
[0028] In certain embodiments, the sensor phasing module 206 corrects flow time interval 232 between the first NOx sensor 108 and the second NOx sensor 110 before the sensor filtering module 212 performs filtering. For example, the sensor phasing module 206 determines the flow time (from exhaust flow and exhaust volume between NOx 108 sensors, 110) of a quantum exhaust flow differential between NOx 108 sensors, 110, buffer values of the first NOx sensor 108 to cover the flow time interval, and align the readings sequences of the NOx sensor 218 from the first NOx sensor 108 and the second NOx sensor 110, from such that the filters are operating in parallel quantum differentials of exhaust flow. The sensor phasing module operations 206 described are exemplary, and any other operation for correcting the flow time between the readings of the first NOx sensor 108 and the second NOx sensor 110 known in the art is contemplated here. Furthermore, a person skilled in the art will further understand that the sensor phasing module 206 can be omitted, and that the inclusion of higher frequency information indicates that the sensor phasing module 206 should be included, and the exclusion of information from Higher frequencies indicate that the sensor phasing module 206 is less beneficial for a particular modality.
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9/23 [0029] The SCR 208 diagnostic module compares the sensor data of the first NOx 108 sensor and the second NOx 110 sensor, which can be phased by the sensor phasing module 206 and / or filtered by the filter module of sensor 212 and thus provided as a comparison of filtered data 234, and provides a sensor condition index 236 in response to the compared values. In certain embodiments, the sensor condition index 236 is provided to a diagnostic output device 114.
[0030] The sensor condition index 236 and the comparison of the first NOx sensor 108 and the second NOx sensor 110 are described here using filtered data. In certain embodiments, the comparison of the first NOx 108 sensor and the second NOx 110 sensor is made with unfiltered data, or only nominally filtered data that is filtered for purposes other than removing frequency-based information from the sensor values - for example, a hardware suppression filter on the electronic signal coming from the sensor. The selection of filtered and unfiltered high-pass filters, and sequential high and low-pass filters can be determined according to the accuracy and desired diagnostic response time for a given system by a person skilled in the art having the benefit of disclosures in this document.
[0031] FIG. 3 is an illustration 300 of raw NOx sensor output. In the illustration in fig. 3, an upper curve 302 is given as an example by a first NOx sensor, and the lower curve 304 is given as an example for a second NOx sensor, where the data is provided over the example operating period. The upper line 306 illustrates an average sensor reading for the first NOx sensor of about 200 ppm, and the lower line 308 illustrates an average sensor reading for the second NOx sensor of about 130 ppm. In the illustration in fig. 3, the ratio between the averages is around 0.65 (second / phmeiro) and the difference in the averages is around 70 ppm. It can also be seen that in many cases, the readings of the first and second NOx sensors are moved opposite (for example, reference around 150 to 190 seconds). A time-domain difference graph between the two sensors would show very significant differences between
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10/23 the sensors. In certain embodiments, one of the first or second sensors from the data in fig. 3 can be determined to be an error sensor, and OBD actions, maintenance actions, motor control actions, and / or other responses may be required due to the differences between the sensors.
[0032] FIG. 4 is an illustration 400 of filtered bandpass Nox sensor outputs 302A, 304A consistent with the unfiltered sensor outputs of fig. 3. Due to the effect of the high pass portion of the filter, it can be seen in the time-domain data that an amount of baseline NOx is removed and the filtered sensor data moves between about -20 ppm and 20 ppm in illustration 400. The filtered NOx sensor outputs 302A, 304A can be used to determine the differences between the outputs of the first and second Nox sensors. Where the first / second ratio was about 0.65 for the unfiltered data in fig. 3, the second / first ratio is about 0.86 for the data filtered in fig. 4. The filtered data of fig. 4 were generated from a bandpass filter with a bandwidth of about 0.15 Hz at the low end to 0.5 Hz at the high end.
[0033] With reference to fig. 5, frequency domain data 500 of the same data set that generates the time domain data of fig. 4. You can see in fig. 5 for both curves 302B, 304B that frequencies outside the pass range (ranging from 0.15 Hz at reference number 502 to 0.50 Hz at reference number 504) are significantly attenuated. The attenuation frequencies for the high pass and / or bandpass filters are set to remove high frequency noise that is above the base NOx detection signal response of the sensors. The response time of the NOx sensors' detection signal varies, and specific values are available from the manufacturer or by testing a particular sensor, but values between 200 ms to 500 ms are typical. Another noise that is filtered out includes noise generated by NOx fluctuations outside the engine, the time interval between the first and second Nox sensors, and high frequency electronic noise loaded at the sensor's communication output. Low frequency noise can also be filtered from the signal, for example, to remove
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11/23 low frequency complicating factors, such as NH3 storage effects of the SCR catalyst.
[0034] With reference to fig. 6, an illustration 600 of an engine NOx output and urea dosing timeline is shown over the period of a diagnostic test. In illustration 600, a post-treatment component regeneration has just been completed (not shown), and an SCR catalyst temperature has been maintained for a predetermined first period of time (for example, for at least 10 minutes) completing a first stage of a NOx sensor diagnosis. The entire first stage of the NOx sensor diagnosis, or only a last portion of the first stage of the NOx sensor diagnosis, can occur during the post-treatment component regeneration event. Due to the fact that the post-treatment component regeneration event involves an elevated temperature over a period of time, the NH3 storage capacity of the SCR catalyst is already reduced at the end at the end of the post-treatment component of the regeneration event.
[0035] In the example of fig. 6, it is determined that a NOx event outside the low engine has occurred (for example, see NOx sensor outputs 602, 604 at 770-790 seconds), and it is determined to enter a second stage of the NOx sensor diagnosis , and dosage of urea 610 is discontinued at the moment 606 (about 810 seconds). The second stage is carried out for a second predetermined period of time, - for example, about 60 seconds in the example - taking stored NH3 levels to a lower level. Right after completing the second stage, a third stage is performed for a third predetermined period of time - about 30 seconds in the example, where urea dosing is still suppressed and where NOx sensor readings are filtered and compared. Right after completion of the third stage, normal urea rejection is restarted at 608 (in about 905 seconds). The diagnosis can also be terminated or paused due to accumulated NOx emissions from the test (due to suppressed urea dosage) exceeding a predetermined threshold or short-term value.
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12/23 [0036] FIG. 7 is an illustration of a diagnostic procedure 700. During a first stage 702 of diagnostic procedure 700, the SCR catalyst experiences an elevated bed temperature that is above a threshold value (for example, 500 ° C) for a period of predetermined time (for example, 5 minutes). The first phase 702 can be started at a time 710 where a post-treatment component regeneration event starts. If the post-treatment component regeneration event provides the elevated temperature for the entire predetermined period ending at time 712, or provides the elevated temperature for a large fraction of the predetermined period, diagnostic procedure 700 continues, whether proceeding to the second stage 704 of diagnostic procedure 700, or keeping the temperature elevated in the SCR catalyst until the predetermined period at time 712 is complete, and then proceeding to second stage 704 of diagnostic procedure 700. During the first stage 702, normal dosing of reducer by the reducer injector is carried out. During the second stage 704, the reducer dosage by the reducer injector is suppressed, and the remaining stored NH3 is expelled from the SCR catalyst. The second phase 704 continues until a second period of time is completed at time 714. The total time for the second phase 704 is based on the temperature of the SCR catalyst and the exhaust gas flow through the SCR catalyst. The temperature and time values for conducting NH3 storage to low acceptable levels are readily determined by a person skilled in the art with a routine data check on a catalyst element, but about 60 seconds at 500 ° C will be sufficient for a typical catalyst element to diagnose a NOx sensor with typical accuracy.
[0037] At the conclusion of the second phase 704, a third phase is performed. The third stage is illustrated in three portions 705, 706, 707 in the example of fig. 7, although the third phase can be performed in a simple portion, as will be understood in the description below. During a third phase 705, 706, 707, dosage of the reducer by the reducer injector is suppressed. NOx sensor outputs
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13/23 are phase filtered and / or corrected, and an average of the NOxé readings compared to determine if one of the NOx sensors is defective. One of the NOx sensors is understood to be the standard, and / or is verified by other means (for example, comparison with NOx at the engine output, or comparison with a third NOx sensor that is not shown), thereby comparison of NOx sensors provides a diagnosis of rationality for the other of NOx sensors. In the example of fig. 7, from a moment 714 to a moment 716, during a first portion 705 of the third phase, sensor data is filtered (and / or phased) and accumulated. In the example, at time 716, a sensor failure, error, or other diagnostic disable condition is detected, which indicates that diagnostic procedure 700 cannot continue, but does not yet need to be aborted. At time 717, after a second portion 706 of the third phase, the disabling condition is removed and the diagnosis is restarted. Certain conditions, including, for example, a total emissions impact that exceeds a threshold or is estimated to exceed a threshold before completion of diagnostic procedure 700, can be used to abort diagnostic procedure 700, either immediately or after a pause, such as the pause illustrated in the second portion 706 of the third phase.
[0038] At time 718, after a third predetermined period of time (equal to the time from time 714 to time 716, added to the time from time 717 to time 718), diagnostic procedure 700 is completed and data accumulated for both sensors are compared. If the ratio of the average NOx detected by the two sensors is within an acceptable range, the NOx sensor is determined to pass. If the average NOx ratio detected by the two sensors is outside the acceptable range, the NOx sensor is not determined to pass, and appropriate fault logic is performed. The NOx sensor can be increased or decreased towards a fault, or a fault can be established or removed based on a simple diagnostic run. Any logic of failure in the art is covered in this document. Diagnostic procedure 700 can be performed after each powder component regeneration event
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14/23 treatment, once per vehicle operation or another platform for the system, or be selectively carried out by any other selection logic included in the art.
[0039] Certain phases can be performed for any purpose, and / or completed under varying, alternating or additional conditions than those listed. The emission limit can be selected according to the emission impact requirements of the particular system, or for any other reason understood in the art. Emission impact requirements vary according to any parameters understood in the art, including at least the engine certification levels, the role of the aftertreatment system in reaching the certification levels, and the required or negotiated emissions effects of the engine. diagnostic procedure.
[0040] Fig.8 is a schematic flowchart 800 of a diagnostic procedure for a NOx sensor. The procedure includes an 802 operation to detect a DPF filter regeneration event, and an 804 determination if the operating conditions of the present engine allow a NOx sensor diagnosis. Where the operating conditions of the present engine support a NOx sensor diagnosis, the procedure includes an 806 operation to maintain an SCR catalyst temperature at a high value for a first predetermined period of time, and a operation 808 to interrupt reducer dosing for a second predetermined period of time. When the reducer dosing is interrupted, the procedure includes an 810 operation to initiate a continuous accumulation of the emissions impact from the diagnostic procedure, and an 812 determination of whether the second predetermined period of time is completed before the emissions impact is exceeded. Where the second predetermined period of time is completed, the procedure includes an operation to continue maintaining the SCR catalyst temperature, to continue suppressing reducer injection, and an 814 operation to filter NOx sensor data for the first and second NOx sensors The filter operation 814 may further include an operation to compensate for a time interval between the first NOx sensor and the second NOx sensor due to the finite gas flow time
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15/23 exhaust from the first NOx sensor to the second NOx sensor. The procedure further includes an 816 determination of whether a third predetermined time is completed before the emission limit is exceeded while filtering the NOx sensor outputs. The procedure also includes an 818 operation to compare the filtered data from the first and second NOx sensors.
[0041] FIG. 9 is an illustration of a data processing operation 900 for NOx sensor diagnostics. The data processing operation 900 includes passing a NOx output at input 902 and a NOx output at output 904 through bandpass filters 906 , 908 and applying a function 910, 912 to each of the outputs. Functions 910, 912 are illustrated as scanning outputs 902, 904.
[0042] Alternative functions 910, 912 include applying a power function to the outputs, applying an absolute value to the outputs, applying a square root to the outputs, removing phase values from the outputs, transforming the outputs into frequency domain data, and / or perform a quick Fourier transform on the outputs. The products of the functions 910, 912 are averaged 914, 916 over the third predetermined time period, and a difference 918 is determined between the averages 914, 916. The difference operation 918 may alternatively include determining a relationship between the averages , apply a function to the averages, and / or provide the averages as inputs to a lookup table. Data processing operation 900 includes a determination 920 whether difference 918 (or another function output) is within the range. In an example mode, the diagnosis has an output value PASS 922 in response to the difference being within the range, and an output value FAIL 924 in response to the difference being out of range.
[0043] As is evident from the figures and text presented here, a variety of modalities according to the present invention are contemplated.
[0044] An example technique for diagnosing a NOx sensor is described. The technique includes operations to diagnose the NOx sensor. The operations illustrated are understood to be by way of example only, and the operations
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16/23 may be combined or divided, and added or removed, and reordered in whole or in part, unless otherwise explicitly stated in this document. Certain illustrated operations can be implemented by a computer running a computer program product in a computer-readable medium, where the computer program product comprises instructions that make the computer perform one or more operations, or issue commands to other devices to perform one or more of the operations.
[0045] The technique includes an operation to raise a temperature of an SCR catalyst for a predetermined period of time while dosing urea (or other reducer). The selective catalytic reduction (SCR) catalyst has at least some ammonia storage capacity. The operation to raise the temperature of the SCR catalyst for a predetermined time reduces ammonia stored in the SCR catalyst to a very low level, or to a negligible level of ammonia. The temperature can be raised to a sufficient level to drive stored ammonia to an acceptable low level (determinable by ammonia storage versus SCR catalyst temperature function, and to the ammonia storage level that supports an accurate diagnostic operation of NOx sensor), for a temperature of at least about 500 ° C, and / or for a regeneration temperature for a post-treatment component (for example, a diesel particulate filter (DPF)). Certain systems carry out periodic high temperature regeneration events in the aftertreatment component - for example, to oxidize soot from a DPF - and the technique described here, in certain modalities, can be performed immediately following such regeneration to minimize the impact diagnosis of fuel economy and system performance. The predetermined time period can also be calculated in real time during a technique operation.
[0046] The technique also includes an operation to maintain the temperature of the SCR catalyst without dosing urea for a second predetermined period of time. The operation to maintain the temperature of the SCR catalyst expels
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17/23 still ammonia remaining from the SCR catalyst, as even at high temperature the SCR catalyst stores some ammonia on the surface in dynamic equilibrium when ammonia is still fed into the SCR catalyst. The maintained temperature can be the same temperature as in the first operation where the dosage of urea (or other reducing agent) was still taking place. However, the temperature maintained may be a different temperature, for example, the temperature during a first operation may be higher (for example, where a regeneration temperature is higher than an ammonia removal temperature) or lower (for example, where a regeneration temperature is lower than the ammonia removal temperature, and / or to save energy during a first operation and increase ammonia removal during a second operation).
[0047] The operation to maintain the temperature of the SCR catalyst takes place for an amount of pre-programmed open cycle time (the second predetermined period of time) that can be about 1 minute, anywhere from 30 seconds to 2 minutes , or any other time determined empirically from testing the SCR catalyst. In certain embodiments, the operation to maintain the temperature occurs in a closed-loop manner, with the operation being completed when a reading from a first NOx sensor corresponds to a reading from a second NOx sensor, when the readings from the first and second NOx sensors reach a constant state value, and / or when a difference between the first and second NOx sensors reaches a constant state value. The second predetermined time period can also be calculated in real time during a technique operation.
[0048] The technique also includes an operation to filter at least low frequency data from the first NOx sensor upstream of the SCR catalyst and from the second NOx sensor downstream of the SCR catalyst. The operation of filtering low frequency data includes running a high pass filter on the data of the first and second NOx sensors. The high pass filter is structured to remove low frequency data, and in certain
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18/23 modalities, it is structured to significantly attenuate frequency data below 0.15 Hz in the data of the first and second NOx sensors. In alternative or additional modalities, the technique also includes an operation to filter high frequency data from the first sensor. NOx upstream of the SCR catalyst and from the second NOx sensor downstream of the SCR catalyst. The operation of filtering high frequency data includes running a bandpass filter on the data of the first and second NOx sensors. The bandpass filter is structured to significantly attenuate frequency data outside the range 0.2 Hz to 0.5 Hz in the first and second data NOx sensors, or alternatively significantly attenuate frequency data outside the 0.3 Hz to 0.5 Hz range in the first and second NOx sensor data.
[0049] The operations of filtering low frequency data, and potentially filtering high frequency data, can be performed with a bandpass filter, or with sequential filtration with a high pass filter and a low pass filter. In alternative modalities, for example, where high precision is desirable and available computing power is readily available, frequency data can be determined by a frequency-based transformation, such as a Fourier or Fast Fourier transform. The data peaks generated through this, with the frequency ranges of interest, can be used in the operation to compare the filtered data described below. The technique also includes an operation to compare filtered data from the first NOx sensor and the second NOx sensor over a third predetermined period of time. The filtered data (either by direct filtration or by transforming and selecting data, as described above) is determined over the third predetermined period of time and a comparison is made. The comparison can be an average magnitude of the reading of the first NOx sensor in relation to an average magnitude of the reading of the second NOx sensor over the test period. Other magnitude comparison techniques comprised in the art can be used, including at least comparing a filtered magnitude from the reading of the first NOx sensor (for example, a
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19/23 low passage of previously filtered values) to a filtered magnitude of the reading of the second NOx sensor or to compare a moving average of the reading of the first NOx sensor to a moving average of the reading of the second NOx sensor. During a third period of predetermined time, operations to maintain the temperature of the SCR catalyst without dosing urea continue.
[0050] The third predetermined time period can be an open cycle time period, such as 30 seconds. In certain embodiments, the third predetermined period of time may be a period of statistical confidence or a period over which the data from the reading of the first NOx sensor overlap with the data from the reading of the second NOx sensor in the domain of time to an extent where the data can be considered to cover the same NOx readings over the same period of time. The statistical confidence period can be determined empirically, for example, by testing sensors that are known to match conditions by simulating the longest operating time interval that will be experienced by the sensors installed in the system (for example, lowest operating fluid flow) until a period of time is determined to be long enough that the flow time interval from the first NOx sensor to the second NOx sensor introduces a negligible error compared to filtered sensor data. The statistical confidence period can also be determined by modeling the system to determine the amount of time that the data should be taken according to the desired confidence level and the estimated time interval of the system.
[0051] In certain embodiments, the technique includes an operation to determine a flow time interval between the first and second NOx sensors, and to compensate for data from the first and second Nox sensors in response to the flow time interval. Where the data from the first and second NOx sensors can be reliably compensated to match the time domain, the third predetermined time period can be reduced to a time period of something greater than about 4 seconds. The determination of the flow time interval depends on the accuracy and response time of the available data, as
Petition 870190111201, of 10/31/2019, p. 26/39
20/23 such as the fluid volumetric flow, the system volume between the first and second NOx sensors, and / or other information that can be used to determine these parameters. The availability, accuracy and response time of time interval information will be understood by those who are versed in the art, contemplating a specific system and having the benefit of the disclosures contained in this document. In certain embodiments, the time interval between the first and second Nox sensors can only be partially compensated, and a third intermediate time period between 4 seconds and 30 seconds is used. The third predetermined time period can also be calculated in real time during a technique operation.
[0052] In certain embodiments, the technique includes an operation to provide a NOx sensor condition index for the first NOx sensor and / or for the second NOx sensor in response to the comparison. For example, when the NOx sensor values match, the first or second NOx sensor can be determined to be faulty, a fault can be fixed, and / or a malfunction indicator lamp or other notification can be activated. The NOx sensor condition index can be qualitative (for example, GOOD, SUSPECTED, FAILED) or quantitative (for example, based on a function of a magnitude relationship between the sensors). Operations for defining a fault or notification may include processing, such as incrementing a fault value before defining a fault, requiring indications of multiple faults before defining a fault, or any other fault control procedures known in the art.
[0053] In certain embodiments, the first NOx sensor is diagnosed in response to an out-of-engine NOx model, and the NOx sensor condition index is determined for the second NOx sensor. For example, if the first sensor NOx is determined to be BOM in response to the first NOx sensor corresponding to a NOx model outside the engine, any difference between the first and second NOx sensors can be attributable to the second NOx sensor.
[0054] In certain embodiments, the technique includes determining whether an engine
Petition 870190111201, of 10/31/2019, p. 27/39
21/23 internal combustion is producing more than a limit amount of NOx, and the operation to maintain the temperature of the post-treatment component without dosing urea (or other reducer) for a second predetermined period of time is delayed and / or aborted in response a determination that the engine is producing more than the limit amount of NOx. The operation to delay or abort the operation to interrupt urea dosing provides control of the total impact of the technique on engine emissions. In many circumstances, emissions during a technique need to be included in the emissions certification for the engine. Certain modalities include the operation to perform the diagnostic technique only at lower levels of engine emissions. In certain embodiments, the technique includes an operation to begin the operation of maintaining the temperature of the post-treatment component without dosing urea for the second predetermined period of time in response to an engine motorized event.
[0055] The technique also includes an operation to perform a data processing operation on the filtered data from the first and second NOx sensors. The data processing operation includes scanning the data, applying a power function to the data, applying a absolute value to the data, apply a square root to the data, and / or remove phase values from the data.
[0056] A set of example modalities is an apparatus including a controller and a plurality of modules structured to functionally perform operations to diagnose a NOx sensor. The apparatus includes a diagnostic staging module that maintains a diagnostic temperature target at an SCR catalyst for a predetermined period of time. The apparatus also includes a reducer dosing module that provides a reducer dosing command. The apparatus also includes a reducer dosing device receptive to the reducer dosing command. The diagnostic stage module also controls, at the end of the predetermined period of time, a reducer dosing module to interrupt reducer dosing for a second predetermined period of time and continue to maintain the diagnostic temperature target. In the end
Petition 870190111201, of 10/31/2019, p. 28/39
22/23 of the second predetermined period of time, the diagnostic staging module still continues to control the reducer dosing module to interrupt reducer dosing and maintain the diagnostic temperature target for a third predetermined period of time. The apparatus includes an SCR diagnostic module which, for a third predetermined period of time, provides a sensor condition index in response to a comparison of data from a first NOx sensor upstream of the SCR catalyst and a second NOx sensor downstream of the SCR catalyst.
[0057] Certain exemplary and non-limiting modalities of the apparatus are described below. An example apparatus includes a sensor filter module that, for a third predetermined period of time, filters sensor data from each between the first NOx sensor and the second NOx sensor. Filtration includes filtering at least data from low frequency response from the sensors. Sample and non-limiting filters include a high pass filter, a band pass filter, and / or a low pass filter and a high pass filter sequentially. The sequential low pass filter and high pass filter can be performed in any order. An example sensor filter module further applies a filter that substantially attenuates sensor frequency data from each sensor below at least 0.15 Hz. Another example sensor filter module also applies a filter that substantially attenuates frequency data. sensor from each sensor outside the 0.2 Hz to 0.5 Hz range. In certain embodiments, the diagnostic temperature target includes a negligible ammonia storage temperature and at least 500 ° C.
[0058] An example apparatus includes a sensor phasing module that corrects a flow time interval between the first NOx sensor and the second NOx sensor before the sensor filtering module filters the sensor data from each sensor. An example SCR diagnostic module also provides the sensor condition index for a diagnostic output device. Sample diagnostic devices include a
Petition 870190111201, of 10/31/2019, p. 29/39
23/23 malfunction, a motor controller, a transmission controller, an after-treatment controller, and / or the data link.
[0059] Although the invention has been illustrated and described in detail in the drawings and in the preceding description, it should be considered as illustrative and not restrictive in nature, it being understood that only certain example modalities have been shown and described, and that all changes and modifications that fall within the spirit of inventions are desirable to be protected. In reading the claims, it is intended that when words such as one, one, at least one, or at least a portion are used there is no intention to limit the claim to just one item, unless otherwise specifically stated in the claim . When the term at least a portion and / or a portion is used the item may include a portion and / or the complete item, unless otherwise specifically stated.

权利要求:
Claims (24)
[1]
1. Method, characterized by understanding:
- raising a temperature of an SCR catalyst for a first predetermined period of time while dosing urea, in which at least part of the first period of time occurs during a post-treatment component regeneration event;
- maintain the temperature of the SCR catalyst without dosing urea for a second predetermined period of time; and
- filter at least low frequency data from a first NOx sensor upstream of the SCR catalyst and a second NOx sensor downstream of the SCR catalyst;
- compare the filtered data from the first NOx sensor and the second NOx sensor without dosing urea over a third predetermined period of time;
- provide a NOx sensor condition index for at least one between the first NOx sensor and the second NOx sensor in response to the comparison;
- determine if the engine is producing more than a limit amount of NOx, and in response to the engine producing more than the limit amount of NOx perform one of:
- delay the maintenance of the temperature of the SCR catalyst without dosing urea for a second predetermined period of time; and
- abort the diagnostic method.
[2]
2. Method according to claim 1, characterized in that it further comprises diagnosing the first NOx sensor in response to a NOx model outside the engine, and in which the provision of the NOx sensor condition index is for the second NOx sensor NOx.
[3]
Method according to claim 1, characterized by the fact that maintaining the temperature comprises maintaining the temperature at between a negligible ammonia storage temperature and at least 500 ° C.
Petition 870190111201, of 10/31/2019, p. 31/39
2/6
[4]
4. Method according to claim 1:
characterized by the fact that the first predetermined period of time comprises between 10 minutes and an ammonia storage reduction time; wherein the second predetermined period of time comprises one between: at least one minute and a period between 30 seconds and two minutes; and in which the third predetermined period of time comprises between: 30 seconds and a period with statistical reliability.
[5]
5. Method according to claim 1, characterized by the fact that the filtration comprises a filtration operation selected from the filtration operations consisting of:
- execute a high pass filter on the data of the first and second NOx sensors; significantly attenuate frequency data below at least 0.15 Hz in the data of the first and second NOx sensors;
- execute a bandpass filter on the data of the first and second NOx sensors; and
- significantly attenuate frequency data outside the range of 0.2 Hz to 0.5 Hz in the data of the first and second NOx sensors.
[6]
Method according to claim 1, characterized in that it further comprises determining a flow time interval between the first and second NOx sensors, compensating the data of the first and second NOx sensors in response to the flow time interval, and wherein the third predetermined period of time comprises a time greater than 4 seconds.
[7]
Method according to claim 1, characterized in that it further comprises starting to maintain the temperature of the post-treatment component without dosing urea for a second predetermined period of time in response to an engine motorization event or low NOx condition outside the engine.
[8]
Method according to claim 1, characterized in that it further comprises performing a data processing operation on the filtered data of the first and second NOx sensors, the data processing operation
Petition 870190111201, of 10/31/2019, p. 32/39
3/6 data comprising an operation selected from operations consisting of:
- scan the data;
- apply a power function to the data;
- apply an absolute value to the data;
- apply a square root to the data;
- remove phase values from the data;
- transform the data into a frequency domain; and
- perform a fast Fourier transform on the data.
[9]
9. Method according to claim 1, characterized by the fact that the comparison comprises determining between a difference and a relationship between first average data from the first NOx sensor and second average data from the second NOx sensor.
[10]
10. Method, characterized by understanding:
- raising a temperature of an SCR catalyst for a first predetermined period of time while dosing urea, in which at least part of the first period of time occurs during a post-treatment component regeneration event;
- maintain the temperature of the SCR catalyst without dosing urea for a second predetermined period of time;
- compare data from a first NOx sensor and a second NOx sensor without dosing urea over a third predetermined period of time;
- provide a NOx sensor condition index for at least one between the first NOx sensor and the second NOx sensor in response to the comparison;
- determine if the engine is producing more than a limit amount of NOx, and in response to the engine producing more than the limit amount of NOx perform one of:
- delay the maintenance of the temperature of the SCR catalyst without dosing urea for a second predetermined period of time; and
Petition 870190111201, of 10/31/2019, p. 33/39
4/6
- abort the diagnostic method.
[11]
Method according to claim 10, characterized in that it further comprises diagnosing the first NOx sensor in response to a NOx model outside the engine, and in which the provision of the NOx sensor condition index is for the second NOx sensor NOx.
[12]
12. Method according to claim 10, characterized in that maintaining the temperature comprises maintaining the temperature at between a negligible ammonia storage temperature and at least 500 ° C.
[13]
13. Method according to claim 10:
characterized by the fact that the first predetermined period of time comprises between 10 minutes and an ammonia storage reduction time; wherein the second predetermined period of time comprises one between: at least one minute and a period between 30 seconds and two minutes; and in which the third predetermined period of time comprises between: 30 seconds and a period with statistical reliability.
[14]
Method according to claim 10, characterized in that it further comprises determining a flow time interval between the first and second NOx sensors, compensating the data of the first and second NOx sensors in response to the flow time interval, and wherein the third predetermined period of time comprises a time greater than 4 seconds.
[15]
Method according to claim 10, characterized in that it further comprises starting to maintain the temperature of the post-treatment component without dosing urea for the second predetermined period of time in response to an engine motorization event or low NOx condition outside the engine.
[16]
16. Apparatus characterized by comprising:
- a diagnostic staging module structured to maintain a diagnostic temperature target on an SCR catalyst for a predetermined first period of time, in which at least part of the first period of time occurs during a powder component regeneration event
Petition 870190111201, of 10/31/2019, p. 34/39
5/6 treatment;
- a reducer dosing module structured to provide a reducer dosing command;
- a reducer doser receptive to the reducer dosing command;
the diagnostic staging module structured further to, at the end of the predetermined period of time, command a reducer dosing module to interrupt reducer dosing for a second predetermined period of time and continue to maintain the diagnostic temperature target;
- the diagnostic staging module structured so that, at the end of the second predetermined period of time, continue to control the reducer dosing module to interrupt reducer dosing and maintain the diagnostic temperature target for a third predetermined period of time; and
- an SCR diagnostic module structured to provide, during the third predetermined period of time, a sensor condition index in response to a comparison of data from a first NOx sensor upstream of the SCR catalyst and a second NOx sensor a downstream of the SCR catalyst;
where the diagnostic staging module is additionally structured to:
- determine a release amount of NOx emissions according to the time to complete the diagnostic procedure, and determine at least one among whether to proceed with, wait to perform, and abort the diagnostic procedure in response to the determined amount of release emissions of Nox.
[17]
Apparatus according to claim 16, characterized in that it further comprises a structured sensor filter module for filtering, during the third predetermined period of time, sensor data from each between the first NOX sensor and the second NOx.
[18]
18. Apparatus according to claim 17, characterized by the fact that the sensor filter module is further structured to filter data from
Petition 870190111201, of 10/31/2019, p. 35/39
6/6 sensor from each sensor applying a filter selected from the filters consisting of: a high pass filter, a band pass filter, a low pass filter and a high pass filter sequentially, and a high pass filter and a low pass filter sequentially.
[19]
19. Apparatus according to claim 17, characterized by the fact that the sensor filter module is further structured to apply a filter that substantially attenuates sensor frequency data from each sensor below at least 0.15 Hz.
[20]
20. Apparatus according to claim 17, characterized by the fact that the sensor filter module is further structured to apply a filter that substantially attenuates sensor frequency data from each sensor outside the 0.2 Hz to 0.5 Hz range.
[21]
21. Apparatus according to claim 16, characterized by the fact that the diagnostic temperature target comprises one between a negligible ammonia storage temperature and at least 500 ° C.
[22]
Apparatus according to claim 16, characterized in that it further comprises a structured sensor phasing module to correct a flow time interval between the first NOx sensor and the second NOx sensor before the sensor filtering module filters sensor data from each sensor.
[23]
23. Apparatus according to claim 16, characterized by the fact that the SCR diagnostic module is further structured to provide the sensor condition index for a diagnostic output device.
[24]
24. Apparatus according to claim 23, characterized in that the diagnostic output device comprises a device selected from the devices consisting of a malfunction indicator lamp, an engine controller, a transmission controller, a post-treatment controller, and a data link.

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法律状态:
2019-01-08| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2020-02-18| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 16/12/2010, OBSERVADAS AS CONDICOES LEGAIS. |

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