CONTROL OF HYDROCARBON INJECTION RATE IN AN EXHAUST GAS ASSEMBLY
An exhaust gas assembly includes an exhaust gas tube configured to receive an exhaust gas from the internal combustion engine, which includes at least one cylinder. An oxidation catalytic device may be operatively connected to the exhaust gas tube and includes a catalyst. A first temperature sensor is operatively connected to the oxidation catalytic device. A controller is operatively connected to the first temperature sensor. A hydrocarbon injector is operatively connected to the controller and configured to selectively inject an amount of hydrocarbon at a hydrocarbon injection rate. The controller includes a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of controlling the hydrocarbon injection rate. The controller may be programmed to limit the hydrocarbon injection rate based at least partially on a combination of space velocity, temperature of the catalyst in the oxidation catalytic device and temperature of a particulate filter.
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The disclosure relates to control of a hydrocarbon injection rate in an exhaust gas assembly.
BACKGROUNDHydrocarbons may be injected into internal combustion engines as fuel, in order to generate power through the combustion process. Additionally, hydrocarbons may be injected into an exhaust gas assembly in order to generate heat for various devices in the exhaust gas assembly. The injected hydrocarbons may interact with components in the exhaust gas to produce heat via an exothermic reaction. Determining the optimal rate of hydrocarbon injection requires balancing multiple factors.
SUMMARYAn exhaust gas assembly includes an exhaust gas tube configured to receive an exhaust gas from an internal combustion engine. The internal combustion engine includes at least one cylinder. An oxidation catalytic device may be operatively connected to the exhaust gas tube and includes a catalyst. A first temperature sensor is operatively connected to the oxidation catalytic device. A controller is operatively connected to the first temperature sensor. A hydrocarbon injector is operatively connected to the controller and configured to selectively inject an amount of hydrocarbon at a hydrocarbon injection rate. The hydrocarbon injector may be in fluid communication with the exhaust gas tube such that the amount of hydrocarbon is released into the exhaust gas tube. The hydrocarbon injector may be in fluid communication with the internal combustion engine such that the amount of hydrocarbon is released into at least one cylinder of the internal combustion engine.
The controller includes a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of controlling the hydrocarbon injection rate. Execution of the instructions by the processor causes the controller to determine a space velocity for the exhaust gas. The controller may be programmed to determine a temperature of the oxidation catalytic device based at least partially on the first temperature sensor. The controller may be programmed to determine a first correction factor (F1) based on the space velocity and the temperature of the oxidation catalytic device. The controller may be programmed to control the hydrocarbon injection rate based at least partially on the first correction factor (F1).
A particulate filter may be operatively connected to the exhaust gas tube. A particulate filter temperature sensor may be operatively connected to the particulate filter. The controller may be programmed to determine a temperature of the particulate filter based at least partially on the particulate filter temperature sensor. The controller may be programmed to determine a second correction factor (F2) based at least partially on the temperature of the particulate filter. The controller may be programmed to control the hydrocarbon injection rate based at least partially on a limited sum of the first and second correction factors (F1, F2). The limited sum is defined as a sum of the first and second correction factors (F1, F2) limited to a maximum value of 1 and a minimum value of 0, via the controller.
The controller may be programmed to limit the hydrocarbon injection rate based at least partially on a combination of space velocity, temperature of the catalyst in the oxidation catalytic device and temperature of the particulate filter. A mass air flow sensor may be configured to sense a flow rate of intake air entering the internal combustion engine. Determining the space velocity may include obtaining an exhaust flow rate of the exhaust gas based at least partially on the mass air flow sensor and a fuel flow rate. Determining the space velocity may include obtaining a density of the exhaust gas at a predefined temperature and a predefined pressure. Determining the space velocity may include obtaining an airspace volume of the oxidation catalytic device.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like reference numbers refer to like components,
The oxidation catalyst 24 may be a precious metal such as palladium, platinum or aluminum oxide, or a combination of all three. The oxidation catalyst 24 may be any suitable catalyst known to those skilled in the art. The oxidation catalyst 24, when heated to a light-off temperature, interacts with and oxidizes components in the exhaust gas 20, such as unburned hydrocarbons and carbon monoxide, to form carbon dioxide and water. An example reaction is shown below:
2CO+O2→2CO2
CxH2x+2+[(3x+1)/2]O2→xCO2+(x+1)H2O
Referring to
Referring to
Referring to
Referring to
The optimal rate of hydrocarbon injection is sensitive to multiple factors. Too low an injection rate results in insufficient heat generated and too high an injection rate results in undesired hydrocarbon slip to the tail pipe and excessive heat generation. The controller 50 includes at least one processor 52 and at least one memory 54 (or any non-transitory, tangible computer readable storage medium) on which are recorded instructions for executing method 100, shown in
Referring now to
In block 104 of
where Exhaust Flow Rate=Air Flow Rate+Total Fuel Flow Rate
In block 106 of
In block 108 of
In a first embodiment, the method 100 proceeds from block 108 to block 110, as indicated by line 109. In block 110 of
In block 112 of
In a second embodiment, additional blocks 114, 116 and 118 may be included, and the method 100 proceeds from block 108 to block 114. In block 114 of
In block 116 of
In block 116 of
In the second embodiment, the method 100 proceeds from block 116 to block 112, in which the controller 50 is programmed to control the hydrocarbon injection rate. In the second embodiment, the controller 50 is programmed to direct the hydrocarbon injector 42 to inject at a corrected injection rate, which is the base injection rate (B) multiplied by the limited sum (LS) such that: Corrected Injection Rate=(LS*B).
A numerical example is presented for illustrative purposes and is not intended to be limiting. In this example, the exhaust flow rate is 52. 3 kg/hr, and the density of the exhaust gas 20 is 1.16 kg/m3 (at the standard temperature 0° C. and standard pressure 1 bar). The airspace volume of the oxidation catalytic device 22 is 0.0015 m3 (1.5 liters). The space velocity (in units of inverse hour or hr−1) is determined to be:
Referring to Table 1, a space velocity (SV) of approximately 30,000 inverse hours and assuming a temperature (T1) of 180° C. leads to a first correction factor (F1) value of 0.80 (in bold). In the first embodiment, with a first correction factor (F1) value of 0.80, a hydrocarbon injection (post-combustion) would be allowed and the base injection rate (B) would be adjusted by a factor of 0.80.
In the second embodiment, with a first correction factor (F1) value of 0.80, the temperature (T2) of the particulate filter 28 would be determined. If the temperature (T2) of the particulate filter 28 is found to be 200° C., the second correction factor (F2) value would be 0.10, according to Table 2. In this case, the sum of (F1+F2) and the limited sum (LS) is 0.90. In this case, the hydrocarbon injection (post-combustion) would be allowed and the base injection rate (B) would be adjusted by a factor of 0.90.
In the second embodiment, if the temperature (T2) of the particulate filter 28 is found to be 150° C., the second correction factor (F2) value would be −1.00, according to Table 2. Here, assuming the first correction factor (F1) is 0.8 as described above, the sum of (F1+F2) is a negative value (0.80−1.00=−0.20). Thus, the limited sum (LS) is zero. In this case, the hydrocarbon injection (post-combustion) would not be allowed because the particulate filter 28 is not sufficiently hot to convert the hydrocarbons that slip past the oxidation catalytic device 22.
The assembly 10 may include multiple oxidation catalytic devices positioned upstream or downstream of the oxidation catalytic device 22. Each oxidation catalytic device in the assembly 10 would include an independent hydrocarbon limitation calibration. For example, referring to
The controller 50 of
Look-up tables, databases, data repositories or other data stores described herein may include various kinds of mechanisms for storing, accessing, and retrieving various kinds of data, including a hierarchical database, a set of files in a file assembly, an application database in a proprietary format, a relational database management assembly (RDBMS), etc. Each such data store may be included within a computing device employing a computer operating assembly such as one of those mentioned above, and may be accessed via a network in any one or more of a variety of manners. A file assembly may be accessible from a computer operating assembly, and may include files stored in various formats. An RDBMS may employ the Structured Query Language (SQL) in addition to a language for creating, storing, editing, and executing stored procedures, such as the PL/SQL language mentioned above.
The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment can be combined with one or a plurality of other desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.
Claims
1. An exhaust gas assembly comprising:
- an exhaust gas tube configured to receive an exhaust gas;
- an oxidation catalytic device operatively connected to the exhaust gas tube and including a catalyst;
- a first temperature sensor operatively connected to the oxidation catalytic device;
- a controller operatively connected to the first temperature sensor;
- a hydrocarbon injector operatively connected to the controller and configured to selectively inject an amount of hydrocarbon at a hydrocarbon injection rate;
- a particulate filter operatively connected to the exhaust gas tube;
- a particulate filter temperature sensor operatively connected to the particulate filter;
- wherein the controller includes a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of controlling the hydrocarbon injection rate, execution of the instructions by the processor causing the controller to: determine a space velocity for the exhaust gas; determine a temperature of the oxidation catalytic device based at least partially on the first temperature sensor; determine a first correction factor (F1) based on the space velocity, the temperature of the oxidation catalytic device and a first look-up repository; determine a temperature of the particulate filter based at least partially on the particulate filter temperature sensor; determine a second correction factor (F2) based on the temperature of the particulate filter and a second look-up repository; and control the hydrocarbon injection rate based at least partially on the first correction factor (F1) and the second correction factor (F2).
2. The assembly of claim 1,
- wherein the control of the hydrocarbon injection rate is based at least partially on a limited sum of the first and second correction factors (F1, F2), the limited sum being defined as a sum of the first and second correction factors (F1, F2) limited to a maximum value of 1 and a minimum value of 0.
3. The assembly of claim 1, wherein the hydrocarbon injector is in fluid communication with the exhaust gas tube and the amount of hydrocarbon is released into the exhaust gas tube.
4. The assembly of claim 1, further comprising:
- an internal combustion engine operatively connected to the exhaust gas tube and having at least one cylinder;
- wherein the hydrocarbon injector is in fluid communication with the internal combustion engine and the amount of hydrocarbon is released into the at least one cylinder of the internal combustion engine.
5. The assembly of claim 1, further comprising:
- an internal combustion engine operatively connected to the exhaust gas tube and having at least one cylinder;
- a mass air flow sensor operatively connected to the internal combustion engine and configured to sense a flow rate of intake air entering the internal combustion engine; and
- wherein said determining a space velocity includes obtaining an exhaust flow rate of the exhaust gas based at least partially on the mass air flow sensor and a fuel flow rate.
6. The assembly of claim 1, wherein said determining a space velocity includes obtaining a density of the exhaust gas at a predefined temperature and a predefined pressure.
7. The assembly of claim 1, wherein said determining a space velocity includes obtaining an airspace volume of the oxidation catalytic device.
8. The assembly of claim 1, further comprising:
- an internal combustion engine operatively connected to the controller;
- a mass air flow sensor operatively connected to the internal combustion engine and configured to sense a mass flow rate of intake air entering the internal combustion engine; and
- wherein said determining a space velocity includes: obtaining an exhaust flow rate of the exhaust gas based at least partially on the mass air flow sensor and a fuel flow rate; obtaining a density of the exhaust gas at a predefined temperature and a predefined pressure; and obtaining an airspace volume of the oxidation catalytic device.
9. A method of controlling an exhaust gas assembly, the assembly having an oxidation catalytic device, a particulate filter, particulate filter temperature sensor, a first temperature sensor, a hydrocarbon injector for selectively injecting an amount of hydrocarbon at a hydrocarbon injection rate, a controller, and an exhaust gas tube configured to receive an exhaust gas, the method comprising:
- sensing a temperature of the oxidation catalytic device via the first temperature sensor;
- determining a space velocity for the exhaust gas;
- determining a first correction factor (F1) based on the space velocity, the temperature of the oxidation catalytic device and a first look-up repository, via the controller;
- sensing a particulate filter temperature of the particulate filter via a particulate filter temperature sensor;
- determining a second correction factor (F2) based on the temperature of the particulate filter and a second look-up repository, via the controller; and
- controlling the hydrocarbon injection rate based at least partially on a limited sum of the first and second correction factors (F1, F2), the limited sum being defined as a sum of the first and second correction factors limited to a maximum value of 1 and a minimum value of 0, via the controller.
10. The method of claim 9, wherein:
- the assembly includes an intake mass air flow sensor operatively connected to the internal combustion engine; and
- said determining a space velocity includes obtaining an exhaust flow rate of the exhaust gas based at least partially on the mass air flow sensor and a fuel flow rate.
11. The method of claim 9, wherein said determining a space velocity includes:
- obtaining a density of the exhaust gas at a predefined temperature and a predefined pressure.
12. The method of claim 9, wherein said determining a space velocity includes:
- obtaining an airspace volume of the oxidation catalytic device.
13. The method of claim 9, wherein the assembly includes a mass air flow sensor and an internal combustion engine, the mass air flow sensor configured to sense a mass flow rate of intake air entering the internal combustion engine; and wherein said determining a space velocity includes:
- obtaining an exhaust flow rate of the exhaust gas based at least partially on the mass air flow sensor and a fuel flow rate;
- obtaining a density of the exhaust gas at a predefined temperature and a predefined pressure; and
- obtaining an airspace volume of the oxidation catalytic device.
14. An exhaust gas assembly comprising:
- an internal combustion engine having at least one cylinder;
- an exhaust gas tube configured to receive an exhaust gas from the internal combustion engine;
- an oxidation catalytic device having a catalyst;
- a particulate filter operatively connected to the exhaust gas tube;
- a particulate filter temperature sensor operatively connected to the particulate filter;
- a first temperature sensor operatively connected to the oxidation catalytic device;
- a controller operatively connected to the first temperature sensor;
- a hydrocarbon injector operatively connected to the controller and configured to selectively inject an amount of hydrocarbon at a hydrocarbon injection rate;
- wherein the controller includes a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of controlling the hydrocarbon injection rate, execution of the instructions by the processor causing the controller to: determine a space velocity for the exhaust gas; determine a temperature of the oxidation catalytic device based at least partially on the first temperature sensor; determine a first correction factor (F1) based on the space velocity, the temperature of the oxidation catalytic device and a first look-up repository; determine a temperature of the particulate filter based at least partially on the particulate filter temperature sensor; and determine a second correction factor (F2) based on the temperature of the particulate filter and a second look-up repository; control the hydrocarbon injection rate based at least partially on a sum (F1+F2) of the first and second correction factors.
Type: Application
Filed: Jan 21, 2016
Publication Date: Jul 27, 2017
Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC (Detroit, MI)
Inventors: Charles E. Dean (Clarkston, MI), Andrea Hidalgo (Clawson, MI), Michelangelo Ardanese (Berkley, MI)
Application Number: 15/002,813