Particulate trap temperature sensor swap detection

An exhaust after-treatment system is disclosed. The system has a particulate trap disposed to remove particulate matter from an exhaust flow of an engine, an upstream temperature sensor disposed to measure a temperature of the exhaust flow upstream of the particulate trap, and a downstream temperature sensor disposed to measure a temperature of the exhaust flow downstream of the particulate trap. The system also has a controller in communication to receive from the upstream and downstream temperature sensors indications of the upstream and downstream temperatures. The controller is configured to compare the upstream and downstream temperatures, determine if the upstream and downstream temperature sensors are improperly swapped based on the comparison, and take a precaution if it is determined that the upstream and downstream temperature sensors are improperly swapped.

TECHNICAL FIELD

The present disclosure is directed to an exhaust after-treatment system, and, more particularly, to an exhaust after-treatment including particulate trap temperature sensor swap detection.

BACKGROUND

Engines, including diesel engines, gasoline engines, gaseous fuel powered engines, and other engines known in the art exhaust a complex mixture of air pollutants. These air pollutants include solid material known as particulate matter or soot. Due to increased attention on the environment, exhaust emission standards have become more stringent, and the amount of particulate matter emitted from an engine is regulated depending on the type of engine, size of engine, and/or class of engine.

One method implemented by engine manufacturers to comply with the regulation of particulate matter exhausted to the environment has been to remove the particulate matter from the exhaust flow of an engine with a device called a particulate trap. A particulate trap is a filter designed to trap particulate matter and typically consists of a wire mesh or ceramic honeycomb medium. However, the use of the particulate trap for extended periods of time may cause the particulate matter to build up in the medium, thereby reducing the functionality of the filter and subsequent engine performance.

The collected particulate matter may be removed from the filter through a process called regeneration. To initiate regeneration of the filter, the temperature of the particulate matter entrained within the filter must be elevated to a combustion threshold at which the particulate matter is burned away. One way to elevate the temperature of the particulate matter is to inject a catalyst such as diesel fuel into the exhaust flow of the engine and ignite the injected fuel. Another way is to use a heating element or a flame-producing burner to heat the filter to the combustion threshold.

One method of controlling regeneration is described in U.S. Patent Application Publication No. 2005/0241301 by Okugawa et al. published on Nov. 3, 2005 (the “301 publication”). The 301 publication discloses a system to control regeneration of a diesel particulate trap (DPF) within an exhaust flow path. The system includes a temperature sensor upstream of the DPF, a temperature sensor downstream of the DPF, and a DPF differential pressure sensor in communication with a controller. As particulate matter accumulates in the DPF, the upstream-downstream pressure difference increases. The controller estimates the amount of accumulation based on the pressure difference and determines a target temperature necessary for regeneration of the DPF based on the amount of accumulation. During subsequent DPF regeneration, the controller operates an upstream oxidation catalyst to heat the DPF to the target temperature and thereby combust all of the accumulated particulate matter.

Although the system of the '301 publication may heat the DPF to an appropriate target combustion temperature, it may malfunction under some circumstances. Specifically, the system uses the upstream temperature sensor to determine the temperature of the DPF during regeneration. Thus, if the upstream temperature sensor and the downstream temperature sensor are installed in the wrong positions (i.e., swapped) due to improper manufacture or assembly, the system may improperly control regeneration. For example, the system may heat the DPF to a temperature far beyond the target and/or for a longer period of time than necessary, causing damage thereto or failure thereof.

This disclosure is directed to overcoming one or more of the problems set forth above.

SUMMARY

One aspect of the disclosure is directed to an exhaust after-treatment system. The system may include a particulate trap disposed to remove particulate matter from an exhaust flow of an engine, an upstream temperature sensor disposed to measure a temperature of the exhaust flow upstream of the particulate trap and a downstream temperature sensor disposed to measure a temperature of the exhaust flow downstream of the particulate trap. The system may further include a controller in communication to receive from the upstream and downstream temperature sensors indications of the upstream and downstream temperatures. The controller may be configured to compare the upstream and downstream temperatures, determine if the upstream and downstream temperature sensors are improperly swapped based on the comparison, and take a precaution if it is determined that the upstream and downstream temperature sensors are improperly swapped.

Another aspect of the disclosure is directed to a method. The method may include disposing a particulate trap to remove particulate matter from an exhaust flow of an engine, receiving from an upstream temperature sensor an indication of a temperature of the exhaust flow upstream of the particulate trap, and receiving from a downstream temperature sensor an indication of a temperature of the exhaust flow downstream of the particulate trap. The method may further include comparing the upstream and downstream temperatures, determining if the upstream and downstream temperature sensors are improperly swapped based on the comparison, and taking a precaution if it is determined that the upstream and downstream temperature sensors are improperly swapped.

DETAILED DESCRIPTION

FIG. 1illustrates a machine10. Machine10may include an operator station11, one or more traction devices12, an engine14, and a particulate trap regeneration temperature control system16. Although machine10is shown as a truck, machine10could be any type of machine having an exhaust-producing engine. Accordingly, traction devices12may be any type of traction devices, such as, for example, wheels, tracks, belts, or any combinations thereof.

Engine14may be any kind of engine that produces an exhaust flow of exhaust gases. For example, engine14may be an internal combustion engine, such as a gasoline engine, a diesel engine, a natural gas engine or any other exhaust gas producing engine.

System16may include an after-treatment device18. After-treatment device18may be any type of device configured to remove one or more constituents from the exhaust flow of engine14. In some embodiments, after-treatment device18may be regenerated by heat or another measure. In one embodiment, after-treatment device18may include a particulate trap19. Particulate trap19may be configured to remove one or more types of particulate matter from the exhaust gases produced by engine14and flowing through an exhaust conduit20configured to direct all or a portion of the exhaust gases produced by engine14to after-treatment device18. Particulate trap19may include an outer housing22, which may encase a filter medium24(e.g. a metal mesh or screen, or a porous ceramic material, such as cordierite) configured to remove (i.e., trap) one or more types of particulate matter from the exhaust flow of engine14.

Although after-treatment device18is discussed herein primarily as being a particulate trap, in other embodiments after-treatment device18may include multifunctional devices such as a combination of a catalytic converter and a particulate trap in the same unit or a catalytic particulate trap, wherein filter medium24may include a catalytic material and/or a catalytic coating.

After-treatment device18may be configured to be thermally regenerated. System16may include a heating system26, which may be configured to increase the temperature of after-treatment device18(i.e., particulate trap19). This may be done using a variety of different means and/or methods. For example, heating system26may be configured to apply heat directly to after-treatment device18via a heating device integrated with or adjacent to after-treatment device18. An example of such a heating device may include an electric heating element (not shown).

Alternatively or additionally, heating system26may be configured to increase the temperature of after-treatment device18by transferring heat to after-treatment device18from the exhaust gases flowing through it. In such embodiments, heating system26may be configured to apply heat to exhaust gases upstream from after-treatment device18. Heating system26may increase the temperature of exhaust gases in one or more ways. For example, altering engine parameters may have an effect on exhaust gas temperature. Running engine14with a “rich” air/fuel mixture may increase exhaust gas temperature. Increases in engine speed and/or load may also increase exhaust gas temperature. Timing and exhaust valve actuation may also be manipulated to control exhaust gas temperatures. Exhaust gases may also be heated by post injection, which involves injecting additional fuel into the combustion chambers after the combustion has taken place, which may result in the additional fuel being burned in the exhaust system, thereby elevating the temperature of the exhaust gases in the system.

Exhaust temperature may also be raised by heating the exhaust gases or exhaust conduit20. For example, heating system26may include one or more heating devices, such as an electric heating element and/or a flame-producing burner configured to heat the exhaust gases or exhaust conduit20. In one embodiment shown inFIG. 2, heating system26may include a regeneration device28configured to reduce an amount of particulate matter in after-treatment device18. In an exemplary embodiment, regeneration device28may include a burner assembly30configured to increase the temperature of the exhaust gases flowing through exhaust conduit20upstream from after-treatment device18.

Burner assembly30may maintain or restore the performance of after-treatment device18through thermal regeneration. Accumulation of exhaust flow constituents in after-treatment device18may result in a decline in engine performance and/or possible damage to after-treatment device18and/or other components of system16. Burner assembly30may thus be configured to prevent or restore any decline in engine performance and avoid possible damage to after-treatment device18and/or other components of system16. For example, burner assembly30may combust (i.e., burn off) at least some of the particulate matter that may have accumulated in after-treatment device18by raising the temperature of after-treatment device18to an appropriate combustion temperature.

Although system16is shown with a single after-treatment device18and a single regeneration device28, system16may include more than one after-treatment device18and/or more than one regeneration device28. For example, in one embodiment, system16may include a single regeneration device28configured to regenerate two after-treatment devices. In another embodiment, system16may include two regeneration devices configured to regenerate two after-treatment devices. In such an embodiment, each regeneration device may be configured to regenerate one of the after-treatment devices or contribute to the regeneration of both of the after-treatment devices. System16could also include any number of regeneration devices and/or after-treatment devices in any combination suitable for regeneration.

FIG. 2illustrates an exemplary embodiment of particulate trap regeneration temperature control system16. For purposes of the following explanation, after-treatment device18will be discussed as being particulate trap19, while regeneration device28will be discussed as being burner assembly30. However, it should be noted that after-treatment device18and regeneration device28could be any of the disclosed types of after-treatment and regeneration devices mentioned above. System16may also include a controller32configured to receive information from various sources and control one or more components of system16based on this information.

Burner assembly30may be positioned anywhere along exhaust conduit20between engine14and particulate trap19(i.e., upstream of particulate trap19). Burner assembly30may include a fuel injector34configured to supply fuel to burner assembly30. Burner assembly30may be configured to create a flame, which may be in a heat exchange relationship with the exhaust flow. System16may be configured to supply fuel injector34with fresh air for mixing with the fuel for combustion, as well as for flushing fuel injector34of any fuel or debris before and/or after operation of burner assembly30. The supply of air to fuel injector34may be regulated by an air valve36, controllable by controller32.

In some embodiments, the source of the fresh air may be an air intake system38of engine14. That is, air may be routed from a portion of air intake system38, such as an intake manifold40, downstream from a compressor42configured to create forced induction for engine14. Compressor42may include a turbocharger, supercharger, or any other device configured to compress intake air and thereby produce forced induction for engine14. Air may be directed from intake manifold40to fuel injector34via an air conduit44. The supply of air to fuel injector34may be regulated by air valve36, which may be controllable by controller32as discussed above.

Burner assembly30may also include a spark plug46configured to provide spark to ignite the air/fuel mixture delivered by fuel injector34. Current may be supplied to spark plug46by an ignition coil48, which may be controlled by controller32. Although burner assembly30has been shown and described as including spark plug46, alternative ignition sources may be employed, such as, for example, glow plugs or another means for igniting an air/fuel mixture.

Controller32may include any means for receiving machine operating parameter-related information and/or for monitoring, recording, storing, indexing, processing, and/or communicating such information. These means may include components such as, for example, a memory, one or more data storage devices, a central processing unit, or any other components that may be used to run an application. Although aspects of the present disclosure may be described generally as being stored in memory, one skilled in the art will appreciate that these aspects can be stored on or read from types of computer program products or computer-readable media, such as computer chips and secondary storage devices, including hard disks, floppy disks, optical media, CD-ROM, or other forms of RAM or ROM. Various other known circuits may be associated with controller32, such as power supply circuitry, signal-conditioning circuitry, solenoid driver circuitry, communication circuitry, and other appropriate circuitry.

Controller32may perform multiple processing and controlling functions, such as, for example, engine management, determining particulate loading, and controlling regeneration of particulate trap19. For instance, controller32may be an engine control module (ECM). Alternatively, machine10may include multiple controllers (a configuration not shown), each dedicated to perform one or more of these or other functions. Such multiple controllers may be configured to communicate and cooperate with one another.

Controller32may be further configured to activate regeneration device28in response to a determination that more than a predetermined amount of particulate matter is or may be trapped in filter medium24. Controller32may also be configured to activate regeneration device28in response to one or more other trigger conditions. These other trigger conditions may include, for example, operation of engine14for a predetermined amount of time; consumption of a predetermined amount of fuel by engine14; detection of an elevated backpressure upstream of particulate trap19above a predetermined pressure; detection of a pressure differential across particulate trap19greater than a predetermined amount; and/or a determination that a calculated or measured amount of particulate matter accumulated in particulate trap19is above a predetermined amount. Controller32may be configured to control regeneration to raise the temperature of particulate trap19, i.e., the temperature of the exhaust flow upstream thereof, to a target combustion temperature at which the accumulated particulate matter may be burned off.

Regeneration may also be initiated manually by an operator, owner, service technician, etc. of machine10. Manually triggering regeneration may be accomplished via a switch, button, or the like associated with machine10and/or a service tool configured to interface with machine10.

System16may include various sensors configured to gather information about operating parameters of system16. Such information may be communicated to controller32for subsequent determinations. For example, system16may include an upstream temperature sensor50, an upstream pressure sensor52, a downstream temperature sensor54, and a downstream pressure sensor56. Such sensors may be positioned along exhaust conduit20upstream and downstream from particulate trap19, respectively, and configured to take measurements of the temperature and pressure of the exhaust gases within exhaust conduit20at their respective locations. These measurements may be communicated to controller32. Specifically, each of sensors50-54may measure its respective temperature or pressure and generate a signal indicative of the measured temperature or pressure. The signals may be communicated to controller32via communication lines74-77, respectively.

Upstream pressure sensor52and downstream pressure sensor56may constitute a pressure differential measurement system. Such a system may be configured to measure a pressure differential between an upstream pressure of the exhaust flow upstream from particulate trap19and a downstream pressure of the exhaust flow downstream from particulate trap19. Alternatively, instead of upstream pressure sensor52and downstream pressure sensor56, the pressure differential measurement system may include a single pressure differential sensor (not shown) configured to measure the difference in pressure between the exhaust flow upstream and downstream of particulate trap19.

System16may also include a ground speed sensor58configured to monitor the ground speed of machine10(i.e., the speed of machine10relative to the surface over which it travels). System16may also be provided with a flame sensing system associated burner assembly30and configured to detect whether burner assembly30is currently producing a flame. Such a flame sensing system may include, for example, a flame sensor60. In addition, system16may include an engine speed sensor62configured to measure the speed at which engine14is operating (i.e., rpm).

The aforementioned sensors may include any type of sensing means suitable for monitoring their respective parameters. In particular, flame sensor60may include any type of sensor suitable for detecting the presence of a flame, such as temperature sensors (e.g., thermocouples), optical sensors, ultraviolet sensors, and ion sensors. Flame sensor60may be configured to detect a condition (e.g., temperature, ultraviolet light, ions, etc.) in proximity to the flame. Such a condition may be monitored at any location within close enough proximity to the flame to enable the presence of the flame to be detected. Additionally or alternatively, the flame sensing system may be configured to detect a rate of change in the condition. For example, a temperature in proximity to the flame location that is increasing at a predetermined rate may indicate that a flame is lit and causing the increase.

In addition or as an alternative to flame sensor60, upstream temperature sensor50may be located upstream of burner assembly30. In such an embodiment, the flame sensing system may be configured to determine whether the downstream exhaust temperature measured by downstream temperature sensor54exceeds the upstream exhaust temperature measured by upstream temperature sensor50by a predetermined amount. A significantly higher downstream temperature may indicate that the flame is lit and is thus heating exhaust gases as they flow through burner assembly30.

Controller32may include a timing device64. Controller32may be configured to couple information from timing device64with information from other sources. For example, controller32may utilize information from timing device64in conjunction with information regarding operation of engine14(e.g., from engine speed sensor62) to determine how long engine14is operated. Timing device64may also be used to monitor and control duration of regeneration events or any other operating parameters of system16and/or machine10.

System16may be configured to control one or more additional system functions and/or parameters. Controller32may be configured to control the pressure of the fuel delivered to fuel injector34(and therefore the rate of fuel injection). A fuel on/off valve66, which may be controllable by controller32, may be associated with fuel injector34to selectively allow fuel to be delivered to fuel injector34. In addition to fuel on/off valve66, system16may also include a fuel pressure regulator valve68controllable by controller32to regulate the pressure of the fuel, and thereby the rate at which fuel is delivered to fuel injector34. In some embodiments, controller32may be configured to control the pressure of fuel delivered to fuel injector34in a closed loop fashion, i.e., in response to pressure measurements taken at or near fuel injector34(e.g., by a fuel pressure sensor, not shown).

Controller32may be further configured to control fuel on/off valve66and/or fuel pressure regulator valve68(i.e., flow of fuel to fuel injector34) in response to other parameters of system16. For example, controller32may be configured to control the temperature of exhaust gases entering particulate trap19in response to feedback from upstream temperature sensor50. This upstream exhaust temperature may be controlled by regulating the amount of fuel and/or air supplied to fuel injector34, which may be accomplished by controlling fuel on/off valve66and/or fuel pressure regulator valve68. Other types of regeneration devices or methods may be controlled in response to measurements taken by upstream temperature sensor50. For example, the amount of post injection may be varied by controller32to regulate the temperature of the exhaust gases entering after-treatment device18.

System16may include multiple fuel pressure regulator valves, which may be independently controlled. At least one fuel pressure regulator valve68may be configured to regulate main fuel pressure, and a second fuel pressure regulator valve (not shown) may be configured to regulate pilot fuel pressure. Pilot fuel pressure may be used during a pilot mode in which system16utilizes a predetermined air/fuel mixture to prevent flameouts during various engine operating conditions, e.g., hard accelerations and rapid decelerations.

Other operating parameters of system16may be monitored to maintain and/or optimize control of the regeneration process. For example, downstream temperature sensor54may detect whether downstream exhaust temperature is above a predetermined temperature. If the downstream exhaust temperature gets too high, it could indicate that temperatures within particulate trap19may be at an undesirably high level as well and/or that the regeneration may be somewhat unstable (e.g., incineration of particulate matter and/or a catalyst driven reaction may be intensifying within after-treatment device18beyond a level commanded by controller32).

System16may also be configured to monitor the stability of the regeneration process by determining a difference between the upstream exhaust temperature measured by upstream temperature sensor50and the downstream exhaust temperature measured by downstream temperature sensor54. If the downstream temperature exceeds the upstream temperature by more than a predetermined amount for more than a predetermined amount of time, for example, controller32may initiate steps to scale back or terminate the regeneration process. For example, in such a case, controller32may reduce the intensity of the flame produced by burner assembly30. In some circumstances, controller32may terminate the regeneration process if the regeneration process is significantly unstable. For example, if the downstream temperature exceeds a predetermined value or exceeds the upstream exhaust temperature by more than a predetermined amount, then controller32may terminate the regeneration process.

Under some circumstances, upstream temperature sensor50and downstream temperature sensor54may be swapped due to improper installation. For instance, upstream temperature sensor50may be installed in the downstream temperature sensor's position, and vice versa; the wiring harness connecting the sensor box (not shown) to temperature sensors50,54may be incorrect; and/or the internal wiring of the sensor box may be incorrect. As a result, controller32may attempt to control the regeneration process based on the wrong temperature indications. This improper control may result in excessive or insufficient regeneration events; increased thermal stress on and failure of after-treatment device18; increased soot loot load on and failure of after-treatment device18; decreased fuel efficiency, and/or increased harmful emissions.

Controller32may implement one or more strategies to detect swapped temperature sensors50,54. It is to be appreciated that, during normal operation of engine14, upstream temperature sensor50may measure a higher temperature than downstream temperature sensor54, because upstream temperature sensor50is closer to the combustion source. In addition, after-treatment device18may slightly insulate downstream temperature sensor54from the combustion source. In one aspect, controller32may determine that upstream temperature sensor50and downstream temperature sensor54are swapped if the measured downstream temperature is greater than the measured upstream temperature. In some applications, however, it may be difficult to detect swapped temperature sensors50,54using this strategy because the upstream temperature and the downstream temperature may be about equal. As such, fluctuations caused by environmental factors and the imprecision or insensitivity of temperature sensors50,54may render difficult detection in this manner of whether temperature sensors50,54are swapped.

Controller32may also utilize the thermal inertia of after-treatment device18to detect whether temperature sensors50,54are swapped. The thermal inertia of after-treatment device18may delay a rise in the downstream temperature caused by a rise in the upstream temperature. That is, the thermal inertia of after-treatment device18may cause the rate of increase of the downstream temperature to be less than the rate of increase of the upstream temperature. As such, for a given operating state, the upstream temperature may reach steady state prior to the downstream temperature. Likewise, after a regeneration event concludes, the thermal inertia of after-treatment device18may cause the downstream temperature to cool down more slowly than the upstream temperature.

Controller32may thus be configured to detect whether temperature sensors50,54are swapped during or after changes in the operating state of machine10, engine14, system14, and/or other associated systems or components. Abrupt changes in the operating state, in particular, may facilitate detection of swapped temperature sensors50,54.

In a first strategy, controller32may check for swapped temperature sensors50,54at the onset of a regeneration event or shortly thereafter, and when the measured upstream and downstream temperatures are within a predetermined range (e.g., 200° C.). Alternatively or additionally, controller32may be configured to wait a specified period of time to elapse since regeneration was initiated. It is to be appreciated that, at a given point during or shortly after initiation of regeneration, the upstream temperature should be predictably greater than the downstream temperature due to the thermal inertia of after-treatment device18. In addition, when the upstream and downstream temperatures are relatively cool (e.g., less than 200° C.), and after-treatment device18is also thus relatively cool, the thermal inertia of after-treatment device18may result in the high exhaust temperatures caused by regeneration to effectuate a rate of downstream temperature increase significantly lower than the rate of upstream temperature increase. In addition, as the temperature of after-treatment device18increases, its thermal inertia may decrease (i.e., it may become “easier” to heat up). The predetermined range (or specified amount of time) may thus be chosen to ensure that the upstream and downstream temperatures are cool enough to allow a temperature sensor swap to be comparatively detected upon a sudden increase or decrease in the upstream temperature.

As such, controller32may check for a temperature sensor swap when after regeneration device28(e.g., burner assembly30) has been activated and the upstream and downstream temperatures are within the predetermined range (e.g., 200° C.), and/or after the specified amount of time has elapsed since the onset of regeneration. This may ensure the upstream and downstream temperatures are cool enough to expose the swap during the regeneration event. Thus, once either or both of the measured upstream and downstream temperatures have risen by a specified amount (e.g., 100° C.), or after a specified period of time (e.g., 10 seconds) stored in memory, controller32may compare the measured upstream and downstream temperatures. Like the predetermined range, it is to be appreciated that the specified period of time may be chosen as to ensure a that temperature sensor50,54swap can be reliably detected, if it is indeed present. These values may be chosen or calculated based on the sensitivity and/or accuracy of temperature sensors50,54; the thermal inertia of after-treatment device; the type of fuel used; and/or other factors.

If the difference between the measured upstream and downstream temperatures is above a threshold (e.g., 50° C.), controller32may determine that temperature sensors50,54are swapped. One of skill in the art will appreciate that by waiting until either or both of the measured upstream and downstream temperatures have risen by the specified amount or until the specified period of time has elapsed, controller32may advantageously utilize the thermal inertia of after-treatment device18to detect whether temperature sensors50,54are swapped. Specifically, if the measured downstream temperature has risen, with respect to the measured upstream temperature, beyond what is reasonably expected under the circumstances, controller32can determine that temperature sensors50,54are swapped. For instance, controller32may determine that temperature sensors50,54are swapped if the following inequality (1) is satisfied:
Tdown−Tup>Tthreshold,  (1)
where Tdownis the downstream temperature measured by downstream temperature sensor54; Tupis the upstream temperature measured by upstream temperature sensor54; and Tthresholdis a specified threshold stored in memory or computed by controller32and known to indicate that temperature sensors50,54are swapped given the circumstances under which Tdown, and Tupare measured and compared (e.g., at the particular point during regeneration). It is to be appreciated that the value of Tthresholdmay depend on particular characteristics of machine10, engine14, after-treatment device18, filter medium14, regeneration device28; the type of fuel used; the operating temperature ranges of system16; and/or other relevant conditions or characteristics. Tthresholdmay be computed based on fleet data gathered in the field for a particular type of machine10, simulation data, and/or any other means known in the art.

In a second strategy, controller32may alternatively or additionally be configured to check for a temperature sensor50,54swap upon the completion of a regeneration event, when the upstream and downstream temperatures are substantially equal. It is to be appreciated that the duration of a regeneration event may be sufficient to cause the downstream temperature to eventually be about the same as the upstream temperature. In other words, a complete regeneration event may result in the upstream and downstream temperatures reaching a steady state condition in which the upstream temperature is about equal to the downstream temperature.

Just as the thermal inertia of after-treatment device18may cause the downstream temperature to increase at a lower rate than the upstream temperature during regeneration, it may likewise cause the downstream temperature to decrease (i.e., cool) at a lower rate than the upstream temperature. That is, when regeneration concludes and the exhaust returns to normal operating temperatures, the exhaust may cool the upstream temperature may more rapidly than the downstream temperature due to the thermal inertia of after-treatment device18. Controller32may thus be alternatively or additionally configured to detect a temperature sensor50,54swap upon completion of a regeneration event. Specifically, upon completion of a regeneration event, controller32may wait until either or both of the measured upstream and downstream temperatures have fallen by a specified amount (e.g., 100° C.), or until a specified amount of time has elapsed since regeneration has completed. If the measured downstream temperature has fallen, with respect to the measured upstream temperature, beyond what is reasonably expected under the circumstances, controller32can determine that temperature sensors50,54are swapped. For instance, controller32may determine that temperature sensors50,54are swapped if the following inequality (2) is satisfied:
Tdown−Tup<Tthreshold,  (2)
where Tdownis the downstream temperature measured by downstream temperature sensor54; Tupis the upstream temperature measured by upstream temperature sensor54; and Tthresholdis a specified threshold stored in memory or computed by controller32and known to indicate that temperature sensors50,54are swapped given the circumstances under which Tdownand Tupare measured and compared (i.e., at the particular point during cool-down). Tthresholdmay be the same as or different than the threshold discussed above with respect to inequality (1).

Controller32may be configured to take one or more precautions if it is determined that temperature sensors50,54are swapped; that is, if inequality (1) or (2) is satisfied, depending on whether the temperature sensor50,54swap check was performed at the onset or completion of regeneration, respectively. For instance, controller32may be in communication with a display70. Display70may be positioned at any suitable location on machine10, e.g., in operator station11. Display70may be any kind of display, including a screen, such as, for example, a cathode ray tube (CRTs), a liquid crystal display (LCDs), a plasma screen, or the like. Display70may be configured to display information about operating parameters of system16. Display70may include a warning indicator72(e.g., a warning lamp, warning message, LEDs, etc.). Controller32may be configured to illuminate warning indicator72upon a determination that sensors50,54are swapped. Alternatively or additionally, controller32may be configured to sound an audible alert upon such a determination. Controller32may also be configured to provide other visual feedback regarding operating parameters of system16or machine10via display70, if desired.

In another aspect, controller32may be configured to log a fault in response to a determination that temperature sensors50,54are swapped. For instance, controller32may store a fault code indicating that temperature sensors50,54are swapped in a machine operation log. The fault code may be used by a technician to diagnose and remedy the problem during maintenance or repair of machine10. Alternatively or additionally, controller32may be configured to terminate a current regeneration event and/or preclude further regeneration events until the swapped temperature condition is remedied (e.g., until a technician repairs and resets the condition).

In yet another aspect, controller32may be further configured to remedy the improperly swapped sensor condition by swapping the temperature signal indications received from temperature sensors50and54via communication lines74and76, respectively. Until the swapped sensor condition is corrected, e.g., by a technician servicing machine10, controller32may use the swapped temperature signal indications in subsequent determinations. For instance, controller32may use the swapped temperature signal indications to control regeneration events as discussed above.

It is to be appreciated that controller32may be configured to similarly manage other faults detected during operation of machine10. For instance, controller32may be configured to log faults when the downstream exhaust temperature exceeds a predetermined temperature or when the downstream exhaust temperature exceeds the upstream exhaust temperature by more than a predetermined amount. Controller32may also be configured to terminate the regeneration process if the number of faults reaches a predetermined value (e.g., when three faults have occurred).

INDUSTRIAL APPLICABILITY

The disclosed particulate trap regeneration temperature control system may be useful to enhance exhaust emissions control for combustion engines. In particular, the disclosed system may be useful to detect situations in which an upstream particulate trap temperature sensor and a downstream particulate trap temperature sensor are swapped due to improper installation. By taking precautions in response to such detected conditions, controlling regeneration events based on improper temperature indications may be avoided. Thus, excessive or insufficient regeneration events; failure of the after-treatment device; decreased fuel efficiency; and/or harmful emissions may be reduced. Operation80of the disclosed system16will now be explained.

Referring toFIG. 3, after machine10has been started (step82), controller32may wait until a regeneration event is initiated or completed in accordance with the monitored parameters, as discussed above, depending on whether the first strategy or the second strategy is implemented, respectively (step84). Immediately after a regeneration event is started—e.g., after burner assembly30is engaged or catalyst is introduced and ignited in exhaust flow—or completed, controller32may begin to check whether temperature sensors50,54are improperly swapped (step86).

In particular, controller32may read the temperature indication signals provided by upstream temperature sensor50and downstream temperature sensor54to determine if the upstream and downstream temperatures are within the specified range suitable for initiating checking whether temperature sensors50,54are improperly swapped (step88). For instance, in implementing the first strategy, controller32may determine whether the upstream and downstream temperatures are sufficiently cool to allow a swap to be detected, as discussed above (e.g., less than 200° C.). In implementing the second strategy, controller32may determine whether the upstream and downstream temperatures are about equal to ensure that the completed regeneration event heated the upstream and downstream temperatures to a steady state.

If the measured upstream and downstream temperatures are determined to be within range in step88, controller32may wait until the measured upstream and/or downstream temperatures have risen or fallen by the specified amount, depending on whether the first strategy or the second strategy is implemented, respectively (step90). If the upstream and/or downstream temperatures have risen or fallen by the specified amount, controller32may determine whether inequality (1) Tdown−Tup>Tthresholdor inequality (2) Tdown−Tup<Tthresholdis satisfied, respectively, as discussed above (step92).

If controller32determines in step92that inequality (1) or inequality (2) is satisfied, controller32may decide that upstream temperature sensor50and downstream temperature sensor54are swapped and take a precaution in response thereto (step94). As discussed above, the precaution may include, for example, logging a fault in a machine operation log; terminating the current regeneration event; disabling future regeneration events; alerting the machine operator (e.g., via display70); and/or swapping the upstream and downstream temperature indication signals receive by controller32via communication lines74,76, and controlling and/or monitoring subsequent regeneration events and/or make other temperature determinations using the swapped indications.

By detecting when the upstream particulate trap temperature sensor and the downstream particulate trap temperature sensor have been swapped due to improper installation and taking precautions in response thereto, the disclosed system may prevent malfunctioning of an exhaust after-treatment system. Specifically, the performance and the longevity of the particulate trap may be preserved and excessive or insufficient regeneration events may be avoided. Further, by preemptively detecting and correcting a temperature sensor swap conditions, operating the machine in this undesirable state may be avoided.

It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the disclosed particulate trap regeneration temperature control system without departing from the scope of the disclosure. Other embodiments will become apparent upon consideration of the specification and practice of the disclosure. For example, step88discussed above may be replaced with a step of waiting for or initiating another high machine operating state (e.g., high engine speed) that may cause the upstream and/or downstream temperatures to rise suddenly and allow the measured upstream and downstream temperatures to be compared in view of the thermal inertia of the after-treatment device. It is intended that the specification and examples be considered as exemplary only, with a true scope of the invention being indicated by the following claims and their equivalents.