Passive nitrogen oxide storage catalyst management
阅读说明:本技术 被动氮氧化物储存催化剂管理 (Passive nitrogen oxide storage catalyst management ) 是由 C·L·怀特 M·A·史密斯 S·任 于 2019-05-28 设计创作,主要内容包括:根据本文描述的一个或多个实施例,一种用于处理来自机动车辆中的内燃机的排气的排气系统包括被动NOx吸收剂(PNA)装置和基于模型的控制器,该基于模型的控制器控制由PNA装置储存的NOx的量。控制所储存的NOx的量包括使用PNA装置的预测模型来计算PNA装置的预测NOx储存水平,并且响应于PNA装置所预测的NOx储存水平大于预定的冷启动阈值,通过改变内燃机的操作来升高排气温度。(According to one or more embodiments described herein, an exhaust system for treating exhaust gas from an internal combustion engine in a motor vehicle includes a Passive NOx Absorber (PNA) apparatus and a model-based controller that controls an amount of NOx stored by the PNA apparatus. Controlling the amount of stored NOx includes calculating a predicted NOx storage level of the PNA device using a predictive model of the PNA device, and increasing an exhaust gas temperature by changing operation of the internal combustion engine in response to the predicted NOx storage level of the PNA device being greater than a predetermined cold start threshold.)
1. An exhaust system for treating exhaust gas from an internal combustion engine in a motor vehicle, the exhaust system comprising:
a Passive NOx Absorber (PNA) apparatus; and
a model-based controller configured to control an amount of NOx stored by the PNA device, the controlling the amount of NOx stored comprising:
calculating a predicted NOx storage level of the PNA device using a predictive model of the PNA device; and
in response to the predicted NOx storage level of the PNA device being greater than a predetermined cold start threshold, increasing the temperature of the exhaust gas by altering operation of the internal combustion engine.
2. The exhaust system of claim 1, wherein the predicted NOx storage level is calculated based on a NOx concentration in the exhaust gas, an exhaust gas flow rate, and a temperature of the exhaust gas.
3. The exhaust system of claim 1, wherein changing operation of the internal combustion engine comprises changing at least one parameter of the internal combustion engine from the group of parameters consisting of fuel injection amount, fuel injection timing, turbocharger air intake, and exhaust gas recirculation rate.
4. The exhaust system of claim 1, wherein the elevated temperature causes the PNA apparatus to release stored NOx, and further comprising:
an emissions reduction device that converts the released NOx to nitrogen (N2) and/or water (H2O).
5. The exhaust system of claim 4, wherein the controlling the amount of stored NOx further comprises:
calculating a predicted conversion capacity of the emissions reduction device based on a predictive model of the emissions reduction device; and
increasing the temperature of the exhaust gas by changing operation of the internal combustion engine in response to a conversion capacity of the emission reduction device being greater than a predetermined threshold.
6. The exhaust system of claim 4, further comprising:
a NOx reduction device located downstream of the PNA device and upstream of the emissions reduction device.
7. A vehicle system, comprising:
an internal combustion engine;
a Passive NOx Absorber (PNA) apparatus; and
a model-based controller configured to control an amount of NOx stored by the PNA device, the control of the amount of NOx stored comprising:
calculating a predicted NOx storage level of the PNA device using a predictive model of the PNA device; and
in response to the predicted NOx storage level of the PNA device being greater than a predetermined cold start threshold, increasing a temperature of exhaust gas from the internal combustion engine by altering operation of the internal combustion engine.
8. The vehicle system according to claim 7, wherein the predicted NOx storage level is calculated based on a temperature of the exhaust gas.
9. The vehicle system of claim 7, wherein changing operation of the internal combustion engine comprises changing at least one parameter of the internal combustion engine from the group of parameters consisting of fuel injection amount, fuel injection timing, turbocharger air intake and exhaust gas recirculation rate.
10. The vehicle system of claim 7, wherein the elevated temperature causes the PNA apparatus to release stored NOx, and further comprising:
an emissions reduction device that converts the released NOx to nitrogen (N2) and/or water (H2O), wherein the controlling the amount of stored NOx further comprises:
calculating a predicted conversion capacity of the emissions reduction device based on a predictive model of the emissions reduction device; and
increasing the temperature of the exhaust gas by changing operation of the internal combustion engine in response to a conversion capacity of the emission reduction device being greater than a predetermined threshold.
Disclosure of Invention
According to one or more embodiments described herein, an exhaust system for treating exhaust gas from an internal combustion engine in a motor vehicle includes a Passive NOx Absorber (PNA) apparatus and a model-based controller that controls an amount of NOx stored by the PNA apparatus. Controlling the amount of stored NOx includes calculating a predicted NOx storage level of the PNA device using a predictive model of the PNA device, and increasing an exhaust gas temperature by changing operation of the internal combustion engine in response to the predicted NOx storage level of the PNA device being greater than a predetermined cold start threshold.
In one or more examples, the predicted NOx storage level is calculated based on a NOx concentration in the exhaust, an exhaust flow rate, and an exhaust temperature. Further, changing the operation of the internal combustion engine includes changing at least one parameter of the internal combustion engine from the group of parameters consisting of fuel injection amount, fuel injection timing, turbocharger intake and exhaust gas recirculation rate.
In one or more examples, the elevated temperature causes the PNA apparatus to release stored NOx, and the exhaust system further comprises a NOx reduction apparatus that converts the released NOx to nitrogen (N2) and/or water (H2O).
Controlling the amount of stored NOx further includes calculating a predicted conversion capacity of the NOx reduction device based on a predictive model of the NOx reduction device, and increasing the temperature of the exhaust gas by changing operation of the internal combustion engine in response to the conversion capacity of the NOx reduction device being greater than a predetermined threshold.
In one or more examples, the exhaust system further includes a Lean NOx Trap (LNT) device located downstream of the PNA device and upstream of the NOx reduction device.
In one or more examples, the NOx reduction device includes a selective catalytic reduction device.
In accordance with one or more embodiments, a vehicle system includes an internal combustion engine, a Passive NOx Absorber (PNA) apparatus, and a model-based controller that controls an amount of NOx stored by the PNA apparatus. Controlling the amount of stored NOx includes calculating a predicted NOx storage level of the PNA device using a predictive model of the PNA device, and increasing an exhaust gas temperature by changing operation of the internal combustion engine in response to the predicted NOx storage level of the PNA device being greater than a predetermined cold start threshold.
In one or more examples, the predicted NOx storage level is calculated based on a NOx concentration in the exhaust, an exhaust flow rate, and an exhaust temperature. Further, changing the operation of the internal combustion engine includes changing at least one parameter of the internal combustion engine from the group of parameters consisting of fuel injection amount, fuel injection timing, turbocharger intake and exhaust gas recirculation rate.
In one or more examples, the elevated temperature causes the PNA apparatus to release stored NOx, and the exhaust system further comprises a NOx reduction apparatus that converts the released NOx to nitrogen (N2) and/or water (H2O).
Controlling the amount of stored NOx further includes calculating a predicted conversion capacity of the NOx reduction device based on a predictive model of the NOx reduction device, and increasing the temperature of the exhaust gas by changing operation of the internal combustion engine in response to the conversion capacity of the NOx reduction device being greater than a predetermined threshold.
In one or more examples, the exhaust system further includes a Lean NOx Trap (LNT) device located downstream of the PNA device and upstream of the NOx reduction device.
In one or more examples, the NOx reduction device includes a selective catalytic reduction device.
According to one or more embodiments, a computer-implemented method for controlling an amount of NOx stored by a Passive NOx Adsorber (PNA) apparatus includes adsorbing NOx in exhaust gas released from an internal combustion engine by the PNA apparatus. The method further includes calculating, by the controller, the predicted NOx storage level of the PNA apparatus using a prediction model of the PNA apparatus. The method further includes increasing the exhaust gas temperature by altering, by the controller, operation of the internal combustion engine in response to the predicted NOx storage level by the PNA device being greater than a predetermined cold start threshold.
In one or more examples, the predicted NOx storage level is calculated based on a NOx concentration in the exhaust, an exhaust flow rate, and an exhaust temperature. Further, changing the operation of the internal combustion engine includes changing at least one parameter of the internal combustion engine from the group of parameters consisting of fuel injection amount, fuel injection timing, turbocharger intake and exhaust gas recirculation rate.
In one or more examples, the elevated temperature causes the PNA apparatus to release stored NOx, and the exhaust system further comprises a NOx reduction apparatus that converts the released NOx to nitrogen (N2) and/or water (H2O).
Controlling the amount of stored NOx further includes calculating a predicted conversion capacity of the NOx reduction device based on a predictive model of the NOx reduction device, and increasing the temperature of the exhaust gas by changing operation of the internal combustion engine in response to the conversion capacity of the NOx reduction device being greater than a predetermined threshold.
In one or more examples, the exhaust system further includes a Lean NOx Trap (LNT) device located downstream of the PNA device and upstream of the NOx reduction device.
In one or more examples, the NOx reduction device includes a selective catalytic reduction device.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description when taken in connection with the accompanying drawings.
Drawings
Other features, advantages and details appear, by way of example only, in the following detailed description, the detailed description referring to the drawings in which:
FIG. 1 is a generalized illustration of an engine and associated exhaust system configured to treat an exhaust stream produced by the engine; and
FIG. 2 depicts a flowchart of an example method for managing a NOx storage catalyst to control NOx emissions of an exhaust system in accordance with one or more embodiments.
Detailed Description
The following description is merely exemplary in nature and is not intended to limit the present disclosure, 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 a processing circuit that may include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory module that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
The treatment of exhaust gas produced by lean burn engines, such as diesel engines, includes various catalytic devices having one or more catalysts disposed on a substrate for reducing the level of regulated constituents in the exhaust gas. For example, diesel exhaust treatment systems may include an oxidation catalyst, also referred to as a diesel oxidation catalyst ("DOC"); and a passive NOx absorber catalyst ("PNA"), such as a diesel cold start catalyst ("dCSC"), that catalyzes the storage of NOx from the engine's cold start. The PNA catalyst can also oxidize HC and CO to CO2 and water. In addition, a selective catalytic reduction ("SCR") catalyst or a Lean NOx Trap (LNT) catalyst may reduce NOx to nitrogen (N2) and/or water (H2O) depending on the reductant. Diesel particulate filters ("DPFs") may be used to remove particulates. In some cases, the SCR and DPF are combined into a single unit, commonly referred to as "SCRF".
In addition, Lean NOx Traps (LNTs) [ also known as NOx Storage Catalysts (NSCs) ] also help to reduce NOx in the exhaust. During normal operation, lean-burn engines produce exhaust emissions having a "lean-burn" composition. LNTs are capable of storing or trapping nitrogen oxides (NOx) present in "lean" exhaust emissions. LNTs store or trap NOx present in exhaust emissions by chemical reaction between the NOx and the NOx storage components of the LNT to form inorganic nitrates. The amount of NOx that can be stored by the LNT is limited by the amount of NOx storage components present. Finally, releasing the stored NOx from the NOx storage component of the LNT; ideally when the downstream SCR device has reached an effective operating temperature. Releasing stored NOx from an LNT is typically accomplished by operating a lean-burn engine under rich conditions to produce an exhaust emission having a "rich" composition. Generally, a fuel-rich condition occurs when the air-fuel ratio is less than a predetermined ratio, such as 14.7: 1. The predetermined ratio is considered to be a perfect mixture of the air-fuel mixture or a theoretical air-fuel ratio. Under these conditions, the inorganic nitrate salt of the NOx storage assembly decomposes to reform NOx. The step of releasing stored NOx from the LNT under rich exhaust conditions is referred to as purging or regenerating the LNT. The technical challenge of LNTs is that they tend to exhibit poor NOx storage efficiency at low temperatures.
In one or more examples, PNAs are used to control emitted NOx emissions from an engine cold start. PNA is involved in catalytically enhanced low temperature NOx storage; once the downstream SCR or SCRF converter reaches the operating temperature required for effective NOx reduction, the stored NOx is subsequently heat released. For example, PNAs can store or adsorb NO at low exhaust temperatures (from room temperature to-200℃.) typically by chemisorptionxAnd release NO at higher temperaturesx. Typical diesel exhaust management systems rely on both temperature and NOx concentration sensing to optimize the performance of a given exhaust treatment device. Such systems typically measure the temperature upstream and downstream of the PNA (or dCSC) and the NOx concentration in the exhaust stream upstream of the PNA (or dCSC) and downstream of the SCR (or SCRF).
The technical challenge of PNA catalysts is that PNA catalysts can only thermally release stored NOx when the exhaust gas temperature reaches a release threshold. This may result in the PNA catalyst being substantially full at the end of the drive cycle, i.e., having a NOx storage capacity below a certain threshold, and therefore unable to further store NOx during the next cold start event. The technical solution described herein addresses such technical challenges by actively managing NOx storage of PNA catalysts.
Fig. 1 and 2 are a general representation of an exhaust system according to the technical solution described herein. In each figure, the left-hand side represents the inlet end of the exhaust treatment device and the right-hand side represents the outlet end of the exhaust treatment device.
FIG. 1 illustrates a
The
The
The
The
6NO+4NH3→5N2+6H2O (1)
4NO+4NH3+O2→4N2+6H2O (2)
6NO2+8NH3→7N2+12H2O (3)
2NO2+4NH3+O2→3N2+6H2O (4)
NO+NO2+2NH3→2N2+3H2O (5)
It should be understood that equations (1) - (5) are exemplary and are not meant to limit emissions control
By monitoring one or more sensor measurements and using a model of
In addition, the
FIG. 2 depicts a flowchart of an
At 230, the storage level is compared to a cold start threshold. The cold start threshold is a predetermined value that can be calibrated. The cold start threshold is a desired amount of NOx stored that allows additional NOx from the
If the predicted storage level of the NOx
As the storage level in the NOx
In one or more examples, the difference between the release threshold and the predicted NOx release value is a conversion capacity of the
The
Alternatively, if the predicted NOx conversion capacity is greater than (or equal to) the threshold conversion capacity, the method includes determining an exhaust temperature that will cause the NOx
The
Accordingly, the technical solution described herein facilitates managing the passive NOx
The technical solution described herein contributes to improvements in emission control systems for internal combustion engines, such as those used in vehicles. For example, the technical solution provides a control strategy that optimizes the overall performance of the exhaust gas treatment system consisting of the
While the foregoing disclosure 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 thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that the disclosure will include all embodiments falling within the scope thereof.
- 上一篇:一种医用注射器针头装配设备
- 下一篇:三元催化器及车辆