Patent Application
20100192546
The present disclosure relates generally to diesel emission abatement devices.
Untreated internal combustion engine emissions (e.g., diesel emissions) include various effluents such as oxides of nitrogen (NOx), hydrocarbons, and carbon monoxide, for example. Moreover, the untreated emissions from certain types of internal combustion engines, such as diesel engines, also include particulate carbon-based matter or “soot”. Federal regulations relating to soot emission standards are becoming more and more rigid thereby furthering the need for devices and/or methods which remove soot from engine emissions.
The amount of soot released by an engine system may be reduced by the use of an emission abatement device such as a filter or trap. Such a filter or trap is periodically regenerated in order to remove the soot therefrom. The filter or trap may be regenerated by use of a burner to burn the soot trapped in the filter.
According to one aspect of the disclosure, a method of operating an emission abatement assembly includes detecting a regeneration event for a particulate filter of the emission abatement assembly. The method further includes detecting whether an engine exhaust intake failure of the emission abatement assembly exists. The method may also include igniting the fuel-fired burner of the emission abatement assembly to regenerate the particulate filter in response to detecting the regeneration event and detecting that the engine exhaust intake failure does not exist.
According to another aspect of the disclosure, a method of operating an emission abatement assembly includes igniting a fuel-fired burner of the emission abatement assembly to combust soot trapped in a particulate filter of the emission abatement assembly. The method also includes detecting an engine exhaust intake failure of the emission abatement assembly. Furthermore, the method includes extinguishing the fuel-fired burner in response to detecting the engine exhaust intake failure of the emission abatement assembly.
According to yet another aspect of the disclosure, an emission abatement system includes a particulate filter, a fuel-fired burner, a sensor and a controller. The particulate filter traps particulates of engine exhaust as engine exhaust flows between an inlet to an outlet of the particulate filter. The fuel-fired burner includes an engine exhaust inlet via which engine exhaust is introduced to the fuel-fired burner, an air inlet via which a flow of air is introduced into the fuel-fired burner, and a fuel inlet nozzle via which a flow of fuel is introduced in the fuel-fired burner. The fuel-fired burner is coupled to the particulate filter inlet to supply the particulate filter with engine exhaust and in response to being ignited to supply the particulate filter with heat to combust soot trapped in the particulate filter. The sensor comprises a inlet-side port proximate to the particulate filter inlet and an outlet-side port proximate to the particulate filter outlet. The sensor generates a signal indicative a differential pressure sensed between the inlet-side port and the outlet-side port. The controller detects whether an engine exhaust inlet failure exists based upon the signal from the sensor, and controls burning of the fuel-fired burner based upon detection of an engine exhaust inlet failure.
As will herein be described in more detail,
Referring now to
As shown in
Again referring to
The fuel-fired burner 16 also includes an electrode assembly having a pair of electrodes 28, 30 as illustratively shown in
The fuel-fired burner 16 also includes a combustion air inlet 36. An air pump, or other pressurized air source such as the truck's turbocharger or air brake system, generates a flow of pressurized air which is advanced to the combustion air inlet 36. During regeneration of the particulate filter 20, a flow of air is introduced into the fuel-fired burner 16 through the air line 39 and the combustion air inlet 36 to provide oxygen (in addition to oxygen present in the exhaust gas) to sustain combustion of the fuel.
As shown in
The filter housing 44 is secured to a housing 46 of a collector 48. Specifically, an outlet 50 of the filter housing 44 is secured to an inlet 52 of the collector housing 46. As such, processed (i.e., filtered) exhaust gas exiting the filter substrate 42 (and hence the filter housing 44) is advanced into the collector 48. The processed exhaust gas is then advanced through a gas outlet 54. In
Referring again to
The mixing baffle 56 functions to mix the hot flow of exhaust gas directed through the combustion chamber 17 and cold flow of exhaust gas that bypasses the combustion chamber 17 during filter regeneration thereby introducing a mixed flow of exhaust gas into the particulate filter 20. In particular, as described above, the flow of exhaust gas swirling in the combustion chamber housing 15 (see
Likewise, the hot flow of exhaust gas is directed toward the hole of the collector plate 62. In particular, the hot flow of exhaust gas is prevented from axially exiting the combustion chamber 17 by a domed flame catch 68. The flame catch 68 forces the hot flow of exhaust gas radially outwardly through a number of openings 70 defined in a perforated annular ring 72, which is similar to the perforated annular ring 62 of the mixing baffle 56. The hot flow of exhaust gas is then directed toward the upstream face 66 of the collector plate 62 by a combination of surfaces including the downstream face 74 of the shroud 27 and the wall 25 of the burner housing 15. The hot flow of exhaust gas then contacts the upstream face 66 of the collector plate where the shape of the plate 62 causes the hot flow of exhaust gas to be directed toward the hole 64. This begins the mixing of the hot flow of exhaust gas with the cold flow of exhaust gas.
Mixing is continued as the cold and hot flows of exhaust gas enter the hole 64 of the collector plate 62. The partially mixed flow of gases is directed into contact with the diverter plate 58. The diverter plate 58 blocks the linear flow of gases and directs them outwardly in radial directions away from the diverter plate 58. The flow of exhaust gas is then directed through a number of openings 76 formed in the perforated annular ring 62 of the mixing baffle 56. This radial outward flow of exhaust gas impinges on the inner surface of the burner housing 15 and is directed through the outlet 40 of the burner housing 15 and into the inlet of the filter housing 44 where the mixed flow of exhaust gas is utilized to regenerate the filter substrate 42.
Hence, the elbow 23 causes the exhaust gas entering the housing 15 to flow in a swirling manner while the exhaust gas flows downstream through the housing 15 as the exhaust gas is split into the bypass and combustion flow. The mixing baffle 56 forces the mixing of the non-homogeneous exhaust gas flow through a narrow area, and then causes the mixed flow to expand outwardly. Swirling the exhaust gas entering the housing 15 and forcing it through the mixing baffle 56, prevents the formation of a center flow or center jet of hot gas from being impinged on the filter substrate 42. This provides a more homogeneous mixture of the hot and cold flows created prior to introduction of the combined flow onto the face of the filter substrate thereby increasing filter regeneration efficiency and reducing the potential for filter damage due to hot spots. It should be appreciated that the elbow 23 and the mixing baffle 56 may be implemented separately, or together, as described herein.
Referring now to
Also shown in
To carry out these tasks, the electronic controller 104 includes a number of electronic components commonly associated with electronic units utilized in the control of electromechanical systems. For example, the electronic controller 104 may include, amongst other components customarily included in such devices, a processor such as a microprocessor 106 and a memory device 108 such as a programmable read-only memory device (“PROM”) including erasable PROM's (EPROM's or EEPROM's). The memory device 108 is provided to store, amongst other things, instructions in the form of, for example, a software routine (or routines) which, when executed by the processor 106, allows the electronic controller 104 to control operation of the emission abatement system 90.
The electronic controller 104 also includes an analog interface circuit 110. The analog interface circuit 110 converts the output signals from the various sensors (e.g., pressure sensors, temperature sensors) into a signal, which is suitable for presentation to an input of the microprocessor 106. In particular, the analog interface circuit 110, by use of an analog-to-digital (A/D) converter (not shown) or the like, converts the analog signals generated by the sensors into a digital signal for use by the processor 106. It should be appreciated that the A/D converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor 106. It should also be appreciated that if any one or more of the sensors associated with the emission abatement assembly 10 generate a digital output signal, the analog interface circuit 110 may be bypassed.
Similarly, the analog interface circuit 110 converts signals from the microprocessor 106 into an output signal which is suitable for presentation to the electrically-controlled components associated with the emission abatement assembly 10 (e.g., the fuel injectors, air valves, igniters, pump motor, etcetera). In particular, the analog interface circuit 110, by use of a digital-to-analog (D/A) converter (not shown) or the like, converts the digital signals generated by the processor 106 into analog signals for use by the electronically-controlled components associated with the emission abatement system 90. It should be appreciated that, similar to the A/D converter described above, the D/A converter may be embodied as a discrete device or number of devices, or may be integrated into the processor 106. It should also be appreciated that if any one or more of the electronically-controlled components associated with the emission abatement assembly 10 operate on a digital input signal, the analog interface circuit may be bypassed.
Hence, the electronic controller 104 may be operated to control operation of the fuel-fired burner 16. In particular, the electronic controller 104 executes a routine including, amongst other things, a closed-loop control scheme in which the electronic controller 104 monitors outputs of the sensors associated with the emission abatement assembly 10 to control the inputs to the electronically-controlled components associated therewith. To do so, the electronic controller 104 communicates with the sensors associated with the emission abatement assembly 10 to determine, amongst numerous other things, the temperature at various locations within the emission abatement assembly 10 and the pressure drop across the filter substrate 42 of the filter 20. Armed with this data, the electronic controller 104 performs numerous calculations each second, including looking up values in preprogrammed tables, in order to execute algorithms to perform such functions as determining when or how long the fuel injectors are operated, controlling the power level input to the electrodes 28, 30 of the burner 16, controlling the air advanced through a combustion air inlet 36, detecting engine exhaust intake failures, etcetera.
It should be appreciated that the electronic controller 104 may communicate directly with the various sensors associated with the emission abatement assembly 10, or may obtain the output from the sensors from an engine control unit (not shown) associated with the engine 92 via a controller area network (CAN) interface (not shown), known to those of skill in the art. Alternatively, exhaust mass flow may be calculated by the electronic controller 104 in a conventional manner by use of engine operation parameters such as engine RPM, turbo boost pressure, and intake manifold temperature (along with other known parameters such as engine displacement). It should be appreciated that the electronic controller 104 may itself calculate the mass flow, or may obtain the calculated mass flow from the engine control unit of the engine 92 via the CAN interface.
As previously discussed, during operation of the engine 92, the filter 20 eventually becomes full of soot from filtering the exhaust gas generated by the engine 92 and needs to be regenerated in order to reduce engine 92 exhaust back pressure for proper engine 92 operation. The processor 106 may be programmed to control the burner 16 based upon various regeneration events such as, for example, predetermined time intervals, event sensing, or other triggering occurrences known to those in the art. Once the fuel-fired burner 16 is activated, it begins to produce heat. Such heat is directed downstream (relative to exhaust gas flow) and into contact with the upstream face of the particulate filter 20. The heat ignites and burns soot particles trapped in the filter substrate 42 thereby regenerating the particulate filter 20. Illustratively, heat in the range of 600-650 degrees Celsius may be sufficient to regenerate a non-catalyzed filter, whereas heat in the range of 300-350 degrees Celsius may be sufficient to regenerate a catalyzed filter.
In an illustrative embodiment, regeneration of the particulate filter 20 may take only a few minutes. The controller 104 may ignite and burn the fuel-fired burner 16 for the duration of the regeneration. For example, the controller 104 may burn the fuel-fired burner 16 for a period of time that has been found sufficient to regenerate the particulate filter 20. In other embodiments, the controller 104 may burn the fuel-fired burner 16 until the controller 104 detects regeneration has completed. For example, the controller 104 may extinguish the burner 16 in response to sensed temperatures indicating completion of the regeneration. The controller 104 may also extinguish the burner 16 in response to a differential pressure across the particulate filter 20 having a predetermined relationship to (e.g. less than) a differential pressure associated with a regenerated filter.
Moreover, it should be appreciated that regeneration of the particulate filter 20 may be self-sustaining once initiated by heat from the burner 16, respectively. Specifically, once the filter 20 is heated to a temperature at which the soot particles trapped therein begin to ignite, the ignition of an initial portion of soot particles trapped therein may cause the ignition of the remaining soot particles much in the same way a cigar slowly burns from one end to the other. In essence, as the soot particles “burn,” an amount of heat is released in the “burn zone.” Locally, the soot layer (in the burn zone) is now much hotter than the immediate surroundings. As such, heat is transferred to the as yet un-ignited soot layer downstream of the burn zone. The energy transferred may be sufficient to initiate oxidation reactions that raise the un-ignited soot to a temperature above its ignition temperature. As a result of this, heat from the fuel-fired burner 16 may only be required to commence the regeneration process of the filter 20 (i.e., begin the ignition process of the soot particles trapped therein).
During its operation, the burner 16 receives an air/fuel mixture, which may be controlled through control of a fuel pump 93 and the addition of combustion air through combustion air inlet 36 of the burner 16. As illustratively shown in
In one embodiment, the controller 104 attempts to detect engine exhaust intake failures and attempts to respond to such failures. An engine exhaust intake failure may result from the engine exhaust inlet pipe 19 becoming disconnected from an emission abatement assembly 10, 12. As a result, not only will the emission abatement assembly 10, 12 not receive engine exhaust due to the disconnected pipe but a potentially dangerous situation may occur if the burner 16 is ignited and/or permitted to continue to burn while the pipe 19 is disconnected. In particular, igniting and/or operating the burner 16 with the pipe 19 disconnected may result in fuel and/or flame exiting the inlet 21 of the burner 16. Such fuel and/or flame exiting the inlet 21 may ignite materials external to the emission abatement assembly 10, 12. Similarly, an engine exhaust inlet failure may occur as a result of a hole forming in the inlet pipe 19 and/or burner housing 15 due to a puncture, corrosion, or some other cause. In such a situation, again igniting and/or operating the burner 16 may result in fuel and/or flame exiting the hole formed in the inlet pipe 19 and/or burner housing 15. As noted above, such fuel and/or flame exiting the emission abatement assembly 10, 12 may ignite material external to the emission abatement assembly 10, 12.
To detect such engine exhaust intake failures, the controller 104 in one embodiment receives a signal S from a sensor 120. The sensor 120 has an inlet-side port 121 in fluidic communication with an interior position of the emission abatement assembly 10 that is proximate the inlet 49 of the filter housing 44. As such, the sensor 120 may sense an inlet-side pressure of the particulate filter 20 via the inlet-side port 121. Similarly, the sensor 120 has an outlet-side port 125 in fluidic communication with an interior position of the emission abatement assembly 10 that is proximate the outlet 50 of the filter housing 44. As such, the sensor 120 may sense an outlet-side pressure of the particulate filter 20 via the outlet-side port 125.
In one embodiment, the sensor 120 comprises a differential pressure sensor 127 coupled between the inlet-side port 121 and the outlet-side port 125. In such an embodiment, the sensor 120 may generate the signal such that the signal is indicative of a differential pressure sensed by the differential pressure sensor 127. As depicted in
In light of the potential dangers associated with an engine exhaust intake failure, the controller 104 as a result of executing the control routine 200 does not ignite the burner 16 and/or extinguishes the burner 16 when such failures are detected. In one embodiment, the controller 104 at 210 may determine whether a regeneration event has occurred. In particular, the controller 104 may determine that an event has occurred that indicates that the particulate filter 20 is in need of being regenerated. For example, the controller 104 may determine that a regeneration event has occurred in response to the pressure across the filter 20 having a predetermined relationship to (e.g. less than) a predetermined differential pressure threshold. The controller 104 may also determine that a regeneration event has occurred in response to determining that a predetermined time period since a previous regeneration has expired. The controller 104 may also determine that a regeneration event has occurred in response to determining that an estimated amount of soot trapped by the particulate filter 20 has a predetermined relationship to (e.g. exceeds) a threshold soot level.
If the controller 104 determines that a regeneration event has not occurred, then the controller 104 may return to 210 in order to periodically check whether a regeneration event has occurred. In response to detecting a regeneration event, the controller 104 may proceed to 220 to determine whether an engine exhaust intake failure has occurred. The controller 104 may determine whether an engine exhaust intake failure has occurred based upon pressures exerted on and/or across the particulate filter 20. In particular, the controller 104 may received the signal S from the sensor 120 and determine whether an engine exhaust intake failure has occurred. As mentioned above, the signal S may comprise a signal indicative of the differential pressure across the particulate filter 20 or may comprise signals indicative of the pressures on the inlet-side and the outlet-side of the particulate filter 20. Regardless, the controller 104 based upon the signal S may monitor the differential pressure across the particulate filter 20.
In such an embodiment, the controller 104 may determine that an engine exhaust intake failure has occurred in response to a rate of change in the differential pressure across the particulate filter 20 having a predetermined relationship to (e.g. greater than) a threshold rate of change. During normal operation of the emission abatement system 90, the rate of change of the differential pressure gradually increases as the particulate filter 20 traps soot and gradually decreases as soot is burnt off by the burner 16. In contrast, an engine exhaust intake failure for the emission abatement assembly 10 may result in a sharp decrease in the differential pressure. For example, upon the gas inlet pipe 19 becoming disconnected from the emission abatement assembly 10, the pressure on the inlet-side of the particulate filter 20 may sharply drop to near atmospheric pressure. Likewise, the differential pressure across the particulate filter 20 may quickly drop to near zero. Thus, by setting the threshold differential pressure to a level less than typically experienced during normal operation, the controller 104 may detect an engine exhaust intake failure in response to the differential pressure across the particulate filter 20 having a predetermined relationship to (e.g. greater than) the threshold differential pressure.
In another embodiment, the controller 104 may likewise monitor the differential pressure across the particulate filter 20 based upon the received signal S. However, instead of detecting an emission abatement failure based upon a rate of change in the differential pressure, the controller 104 may detect an engine exhaust intake failure in response to the differential pressure across the particulate filter 20 having a predetermined relationship to (e.g. less than) a threshold differential pressure. As mentioned above, the differential pressure across the particulate filter 20 may drop to near zero in response to an engine exhaust intake failure. Accordingly, in one embodiment, a threshold differential pressure may be defined that specifies differential pressures below which are indicative of an engine exhaust intake failure. Thus, the controller 104 may detect an engine exhaust intake failure in response to the differential pressure across the particulate filter 20 having a predetermined relationship to (e.g. less than) a threshold differential pressure associated with an engine exhaust intake failure.
In other embodiments, the controller 104 may detect an engine exhaust intake failure based upon solely an inlet-side pressure of the particulate filter 20 instead of the differential pressure across the particulate filter 20. Again, the rate of change of the inlet-side pressure is likely to sharply decrease in response to an engine exhaust intake failure. Moreover, the inlet-side pressure is likely to drop to near atmospheric levels in response to an engine exhaust intake failure. Accordingly, a threshold pressure may be defined that specifies pressures below which are indicative of an engine exhaust intake failure. The controller may then detect an engine exhaust intake failure in response the inlet-side pressure of the particulate filter 20 having a predetermined relationship to (e.g. less than) the threshold pressure associated with an engine exhaust intake failure. Similarly, a threshold rate of change may be defined that specifies rates above which are indicative of an engine exhaust intake failure. The controller 104 may then detect an engine exhaust intake failure in response to a rate of change of the inlet-side pressure of the particulate filter 20 having a predetermined relationship to (e.g. greater than) the threshold rate of change associated with an engine exhaust intake failure.
If the controller 104 determines that the an engine exhaust intake failure has not occurred, then the controller 104 may proceed to 260 to extinguish the fuel-fired burner 16 or ensure the fuel-fired burner is extinguished. Otherwise, the controller 104 at 230 may ignite the fuel-fired burner 16. To this end, the controller 104 may active the fuel pump 93 to deliver fuel and may open the valve 114 to deliver air to the burner 16.
After igniting the fuel-fired burner 16, the controller 104 at 240 may again determine whether an engine exhaust intake failure has occurred. The controller 104 may make such a determination in a manner similar to the manner discussed above in regard to 220. Like 220, if the controller 104 determines an engine exhaust intake failure has occurred, the controller 104 may proceed to 260 to extinguish the fuel-fired burner 16.
At 250, the controller 104 may determine whether the regeneration of the particulate filter 20 is complete. If complete, the controller 104 may proceed to 260 to extinguish the fuel-fired burner 16. If not complete, the controller 104 may return to 240 to ensure an engine exhaust intake failure has not occurred. At 250, the controller 104 may use various techniques to detect completion of the filter regeneration. For example, the controller 104 may determine the regeneration is complete in response to determining that a specified period of time sufficient to regenerate the particulate filter 20 has elapsed since igniting the fuel-fired burner 16. The controller 104 may also determine the regeneration is complete based upon sensed temperatures of the emissions abatement assembly 20. Further, the controller 104 may determine the regeneration is complete based upon the differential pressure across the particulate filter 20. As mentioned above, the differential pressure across the particulate filter 20 gradually decreases as the particulate filter 20 is regenerated. Accordingly, a threshold differential pressure may be defined that specifies a differential pressure that is indicative of a regenerated filter. The controller 104 may then determine that regeneration of the particulate filter 20 is complete in response to determining that the differential pressure across the particulate filter 20 has a predetermined relationship to (e.g. less than) a threshold differential pressure associate with a regenerated filter.
As noted above, the controller 104 may also detect an engine exhaust intake failure in response to the differential pressure across the particulate filter 20 having a predetermined relationship to (e.g. less than) a threshold differential pressure associated with an engine exhaust intake failure. In practice, the threshold differential pressure associated with an engine exhaust intake failure is less than the threshold differential pressure associated with a regenerated filter. Accordingly, in one embodiment, the threshold differential pressures for a regenerated filter and an engine exhaust intake failure are defined such that the controller 104 may distinguish between a regenerated filter and an engine exhaust intake failure.
At block 260, the controller 104 may extinguish the fuel-fired burner 16. In one embodiment, the controller 104 closes the valve 114 to cease delivery of air from the air supply 112 and deactivate the fuel pump 93 to cease delivery of fuel from the fuel supply 117. However, it should be appreciated that the fuel-fired burner 16 may also be extinguished by merely deactivating the fuel pump 92.
While the disclosure is susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and has herein be described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.
There are a plurality of advantages of the present disclosure arising from the various features of the apparatus, systems, and methods described herein. It will be noted that alternative embodiments of the apparatus, systems, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of apparatus, systems, and methods that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present disclosure. For example, it should be appreciated that the order of many of the steps of the control routines described herein may be altered. Moreover, many steps of the control routines may be performed in parallel with one another.
