Patent Grant
7698887
The present disclosure relates generally to emissions traps for trapping emissions present in exhaust gas.
Emissions traps are used to trap and thus remove emissions from exhaust gas to reduce discharge of emissions to the atmosphere. From time to time, emissions traps are “regenerated.” During such regeneration events, emissions trapped by an emissions trap are purged therefrom for further use of the emissions trap.
A soot trap is one type of emissions trap. A soot trap is used to trap and thus remove soot from exhaust exhaust. It is regenerated by burning off the soot trapped thereby.
A NOx trap is another type of emissions trap. A NOx trap is used to trap and thus remove NOx (i.e., oxides of nitrogen) from exhaust gas when the exhaust gas is relatively lean (i.e., has excess oxygen). The NOx trap is regenerated in the presence of a NOx-reducing agent [e.g., fuel, hydrogen (H2), carbon monoxide].
According to an aspect of the present disclosure, there is provided an apparatus for determining local emissions loading of an emissions trap and regenerating the emissions trap when local emissions loading of the emissions trap satisfies predetermined regeneration criteria. The apparatus comprises a loading determination device configured to determine emissions loading of a first local region of the emissions trap and emissions loading of a second local region of the emissions trap. The emissions trap is regenerated if such emissions loading information about the first and second local regions satisfies the predetermined regeneration criteria.
The emissions trap may be, for example, a soot trap or a NOx trap. In the case of a soot trap, the loading determination device is configured to determine soot loading of the first local region and soot loading of the second local region. In the case of NOx trap, the loading determination device is configured to determine NOx loading of the first local region and NOx loading of the second local region.
In an implementation, the loading determination device is configured to measure an electrical resistance of the first local region and an electrical resistance of the second local region. Such measured electrical resistance is representative of the emissions loading (e.g., soot loading, NOx loading) of the local regions.
According to another aspect of the disclosure, an associated method is disclosed.
The above and other features of the present disclosure will become apparent from the following description and the attached drawings.
While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will 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 following within the spirit and scope of the invention as defined by the appended claims.
Referring to
The emissions trap 14 may be, for example, a soot trap configured as a catalyzed or uncatalyzed substrate to trap soot present in exhaust gas. In such a case, the device 12 is configured to determine local soot loading of a plurality of regions of the soot trap (e.g., local region 18a and local region 18b). The device 12 thus provides means for determining soot loading of a first local region 18a of the soot trap and soot loading of a second local region 18b of the soot trap.
In another example, the emissions trap 14 may be a NOx trap to trap NOx present in exhaust gas. In such a case, the device 12 is configured to determine local NOx loading of a plurality of regions of the NOx trap (e.g., local region 18a and local region 18b). The device 12 thus provides means for determining NOx loading of a first local region 18a of the NOx trap and NOx loading of a second local region 18b of the NOx trap.
It is to be understood that what is meant herein by the term “local region” of the emissions trap 14 is only a portion of the emissions trap 14 rather than the emissions trap as a whole. The device 12 is thus able to determine emissions loading of a first portion or “local region” of the emissions trap 14, emissions loading of a second portion or “local region” of the emissions trap 14, and possibly other portions or “local regions” of the emissions trap 14. As such, in the case where the trap 14 is a soot trap, the device 12 operates in a manner that is different from systems that determine the overall soot loading of a soot trap as a whole (e.g., by measuring the pressure drop across the soot trap using a pressure sensor upstream from the soot trap and a pressure sensor downstream from the soot trap). In addition, in the case where the trap 14 is a NOx trap, the device 12 operates in a manner that is different from systems that determine the overall NOx loading of a NOx trap as a whole (e.g., by measuring NOx loading with NOx sensors present upstream and downstream from the NOx trap).
A controller 20 is electrically coupled to the device 12 via an electrical line 22 to receive the emissions loading information (e.g., soot loading information, NOx loading information) from the device 12. The controller 20 is further electrically coupled to a trap regenerator 24 via an electrical line 26 to operate the trap regenerator 24 to regenerate the emissions trap 14 if the emissions loading information about the local regions 18a and 18b and other tested local regions, if any, of the emissions trap 14 satisfies predetermined regeneration criteria. For example, in the case where the trap 14 is a soot trap, the controller 20 operates the trap regenerator 24 to burn off soot trapped by the soot trap to thereby regenerate the soot trap if the soot loading information about the tested local regions satisfies the predetermined regeneration criteria. In the case where the trap 14 is a NOx trap, the controller 20 operates the trap regenerator 24 to introduce a NOx-reducing agent [e.g., fuel, hydrogen (H2), carbon monoxide] to the NOx trap to reduce NOx trapped by the NOx trap to thereby regenerate the NOx trap if the NOx loading information about the tested local regions satisfies the predetermined regeneration criteria.
Referring to
In the particular non-limiting example shown in
The electrical circuitry 32 is configured to apply a voltage between a selected pair of the electrodes 30a, 30b, 30c, 30d, 30e to determine the electrical resistance and thus the emissions loading (e.g., soot loading, NOx loading) of the associated local region 118a, 118b, 118c, 118d, 118e and to provide a signal representative of the emissions loading of that local region to the controller 20 via the electrical line 22. The electrical circuitry 32 applies a voltage between electrodes 30a and 30e to determine the electrical resistance and thus emissions loading of the outer local region 118a, applies a voltage between electrodes 30b and 30e to determine the electrical resistance and thus emissions loading of the outer local region 118b, applies a voltage between electrodes 30c and 30e to determine the electrical resistance and thus emissions loading of the outer local region 118c, and applies a voltage between the electrodes 30d and 30e to determine the electrical resistance and thus emissions loading of the outer local region 118d. To determine the electrical resistance and thus emissions loading of the inner local region 118e, the electrical circuitry 32 applies a voltage between opposed electrodes 30a and 30c or opposed electrodes 30b and 30d. As such, the loading determination device 12 is configured to determine circumferential and radial distribution of emissions (e.g., soot, NOx) in the emissions trap 14.
The electrical circuitry 32 is electrically coupled to the controller 20 via the electrical line 22. As such, the electrical circuitry 32 is configured to send to the controller 20 signals representative of electrical resistance information and thus emissions loading information (e.g., soot loading information, NOx loading information) about the local regions 118a, 118b, 118c, 118d, 118e. In response thereto, the controller 20 is configured to operate the trap regenerator 24 to regenerate the trap 14 if the electrical resistance information/emissions loading information satisfies predetermined regeneration criteria.
As alluded to above, the electrical circuitry 32 serves as a voltage source to apply the voltage between the electrodes. The applied voltage may be an AC voltage (i.e., alternating current voltage) or a DC voltage (i.e., direct current voltage). A relatively high AC voltage (in the kilovolt or megavolt range) would facilitate resolution of the electrical resistance and emissions loading of the associated local region 118a, 118b, 118c, 118d, 118e. It should be understood that the electrical circuitry 32 may include one or more electrical resistors and/or other electronic devices (not shown) to facilitate determination of the electrical resistances of the local regions 118a, 118b, 118c, 118d, 118e.
Referring to
As such, in this particular additional example of the device 12, the device 12 includes a plurality of ring-shaped sets 35 of circumferentially-spaced internal electrodes 30a, 30b, 30c, 30d arranged as shown in
In the case where there are multiple internal electrode sets 35, the outer electrode/housing 30e surrounds each electrode set 35 and is electrically coupled to the electrical circuitry 32 via the electrical line 34e. In addition, each internal electrode set 35 has associated therewith the electrical lines 34a, 34b, 34c, 34d electrically coupling the internal electrodes 30a, 30b, 30c, 30d to the electrical circuitry 32. The electrical circuitry 32 is thus configured to apply an AC or DC voltage between selected pairs of electrodes 30a, 30b, 30c, 30d, 30e and to provide signals representative of electrical resistance information and thus emissions loading information (e.g., soot loading information, NOx loading information) about the local regions 118a, 118b, 118c, 118d, 118e of the emissions trap 14 to the controller 20.
As such, the electrical circuitry 32 is configured to send to the controller 20 signals representative of electrical resistance information/emissions loading information about the local regions 118a, 118b, 118c, 118d, 118e at axial locations along the axis 36. In response thereto, the controller 20 is configured to operate the trap regenerator 24 to regenerate the trap 14 if the electrical resistance information/emissions loading information satisfies predetermined regeneration criteria.
It is within the scope of this disclosure for the electrical circuitry 32 to take electrical resistance readings in a serial manner or in a parallel manner. In particular, the electrical circuitry 32 may take electrical resistance readings one at a time or may take two or more electrical resistance readings simultaneously.
It is within the scope of this disclosure for the predetermined regeneration criteria to take a variety of forms. In a non-limiting example, regeneration may be initiated if emissions loading (e.g., soot loading, NOx loading) of only one of the tested local regions exceeds a predetermined threshold. In another non-limiting example, regeneration may be initiated if emissions loading (e.g., soot loading, NOx loading) of some combination of tested local regions exceeds a predetermined threshold.
While the concepts of the present disclosure have been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.
There are a plurality of advantages of the concepts of the present disclosure arising from the various features of the systems described herein. It will be noted that alternative embodiments of each of the systems 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 a system that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the invention as defined by the appended claims.
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