Patent Application
20130086886
The subject invention relates to methods, and systems for regenerating particulate matter in an electrically heated oxidation catalyst.
An oxidation catalyst device is provided in an exhaust system to treat unburned gaseous and non-volatile hydrocarbon (HC) and carbon monoxide (CO). The oxidation catalyst oxidizes the HC and CO under high temperatures conditions to form carbon dioxide (CO2) and water (H2O). A heating system is provided in the exhaust system to create the high temperature conditions for the oxidation process. Under various operating conditions, damage can occur to the heating system that prevents proper operation of the oxidation catalyst. Accordingly, it is desirable to provide methods and systems that prevent damage to the heating system and that ensure operation of the oxidation catalyst.
In one exemplary embodiment, a control method for a heating device of an oxidation catalyst is provided. The control method includes: estimating an accumulation of particulate matter on the heating device; and selectively controlling a switching device in electrical communication with the heating device based on the estimated accumulation.
In another exemplary embodiment, an exhaust system of an engine is provided. The exhaust system includes: an oxidation catalyst; a heating device associated with the oxidation catalyst; and a control module that estimates an accumulation of particulate matter on the heating device, and that selectively controls a switching device in electrical communication with the heating device based on the estimated accumulation.
In yet another exemplary embodiment, a vehicle is provided. The vehicle includes: an engine; an electrically heated oxidation catalyst that receives exhaust gas from the engine; and a control module that controls current to the electrically heated oxidation catalyst based on an estimation of accumulated particulate matter in the electrically heated oxidation catalyst.
The above features and advantages and other features and advantages of the invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings.
Other features, advantages and details appear, by way of example only, in the following detailed description of embodiments, the detailed description referring to the drawings in which:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
Referring now to
The exhaust gas treatment system 10 generally includes one or more exhaust gas conduits 14, and one or more exhaust treatment devices. The exhaust treatment devices include, for example, an oxidation catalyst (OC) 18, a selective catalytic reduction device (SCR) 20, and a particulate filter device (PF) 22. As can be appreciated, the exhaust gas treatment system 10 of the present disclosure may include the OC 18 and various combinations of one or more of the exhaust treatment devices shown in
In
To aid in the oxidation process, an electrically heated device (EHD) 30 is disposed upstream of the OC 18. The EHD 30 provides the high temperature necessary to oxidize the HC and CO. Current is controlled to the EHD 30 periodically to initiate the oxidation process in the OC 18. In various embodiments, the EHD 30 may be constructed using a monolith filter that has an inlet and an outlet in fluid communication with the exhaust gas conduit 14. As can be appreciated, the monolith filter described herein is merely exemplary in nature and that the EHD 30 may include other filter devices known in the art.
As the exhaust gas 13 passes through the EHD 30, particulate matter of the exhaust gas may be deposited on the EHD 30. If too much particulate matter is accumulated on the EHD 30, the EHD 30 may short circuit when activated. Thus, the EHD 30 is selectively activated to regenerate the particulate matter that is deposited on or near the EHD 30. A control module 32 monitors the operating conditions of the engine 12 and/or the exhaust treatment system 10 and controls the current to the EHD 30 through a switching device 34. In general, the control module 32 controls the current by estimating the accumulation of particulate matter on or near the EHD 30 and selectively controls the switching device 34 based on the estimated accumulation.
Referring now to
The particulate matter estimation module 40 receives as input engine parameters 44 (such as, but not limited to engine speed, fuel, barometric pressure, ambient air temperature, NO2, Lambda, exhaust gas recirculation rate, exhaust flow, and exhaust temperature,), and exhaust parameters 46 (such as, but not limited to, exhaust flow, exhaust temperature, exhaust gas recirculation rate, Lambda, HC, NO2, and cell density). Such parameters can be either sensed and/or modeled. The particulate matter estimation module 40 estimates the particulate matter generated by the engine 12, also referred to as the particulate matter rate based on the engine parameters. For example, the engine particulate matter can be estimated based on the engine parameters and estimation methods known in the art.
The particulate matter estimation module then estimates the particulate matter accumulated in or near the EHD 30 based on the engine particulate matter and the exhaust parameters 46. For example the particulate matter can be estimated based on exhaust parameters 46 and estimation methods known in the art.
The heater activation module 42 receives as input the estimated PM 48. The heater activation module 42 evaluates the estimated PM 48 to determine whether current should be controlled to the EHD 30. In various embodiments, if the estimated PM 48 is greater than a predetermined threshold, the heater activation module 42 activates the EHD 30 by controlling the switching device 34 to allow current to flow to the EHD 30 via control signal 50. The heater activation module 42 selectively controls the flow of current to the EHD 30 until the particulate matter has been regenerated successfully (e.g., by evaluating feedback parameters 49 that indicate, for example change in backpressure in the engine, or by evaluating exhaust temperature after the OC 18, etc.). At which point, the heater activation module 42 deactivates the EHD 30 by controlling the switching device 34 to prevent current to flow to the EHD 30 via control signal 50.
Referring now to
In various embodiments, the method can be scheduled to run based on predetermined events, and/or run continually during operation of the engine 12.
In one example, the method may begin at 100. The engine particulate matter is predicted at 110; and the estimated PM 48 is estimated based thereon at 120. The estimated PM 48 is evaluated at 130. If the estimated PM 48 is greater than a predetermined threshold at 130, the EHD 30 is activated by generating the control signal 50 to the switching device 34 at 140. The EHD 30 remains active at until a threshold temperature is reached at 150 and the particulate matter has been regenerated at 160. Thereafter, the EHD 30 can be deactivated via the control signal 50 at 170 and the method may end at 180.
If, however, the estimated OC PM is less than the predetermined threshold at 130, there is not sufficient matter to create a thermal event within the oxidation catalyst and the method may end at 180.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the application.
