Engine emission control method and device, storage medium, system and vehicle

Abstract

The embodiment of the invention provides an engine emission control method and device, a storage medium, a system and a vehicle, and belongs to the field of engine control. The method comprises the following steps: acquiring a first-stage oxygen storage amount treated by a first-stage treatment device in the last driving cycle of the engine; in the current driving cycle, whether the air-fuel ratio is corrected by using the first-stage measurement data processed by the first-stage processing device or by using the second-stage measurement data processed by the second-stage processing device is determined by judging whether the first-stage oxygen storage amount exceeds a preset threshold value. According to the embodiment of the invention, in the application that the vehicle treats the exhaust gas through the two-stage treatment device, after the post-treatment conversion efficiency of the first-stage treatment device is reduced, the post-treatment conversion capacity of the second-stage treatment device can be fully utilized, and then the durability life of post-treatment is prolonged; and gas emission can be accurately controlled, and the content of post-treated precious metal is reduced to a greater extent under the condition that the requirement for emission durability is met.

Description

Technical Field

[0001] The present invention relates to the technical field of engine control, and in particular to an engine emission control method, a control device, a storage medium, a system and a vehicle. Background Art

[0002] The exhaust gas produced by gas (e.g., natural gas) engines must be treated to remove harmful substances such as nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC) before they can be discharged. The three-way catalytic converter (Three-Way-Catalyst) can convert harmful gases such as CO, HC, and NOx emitted from automobile exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction. It is the most important external purification device installed in the automobile exhaust system. If the three-way catalytic converter ages, it will seriously affect the treatment effect of automobile exhaust, causing the vehicle to fail to meet the increasingly stringent emission regulations.

[0003] The existing two-stage three-way catalytic converter post-treatment emission control strategy for natural gas engines uses the post-oxygen voltage measured at the post-treatment outlet of the first-stage treatment device to correct the air-fuel ratio, thereby ensuring the activity of the post-treatment and effective control of pollutants. Its disadvantage is that after the post-treatment conversion efficiency of the first-stage treatment device is reduced, emissions deteriorate seriously. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide an engine emission control method, which can solve the problem of serious emission deterioration caused by the reduction of the post-processing conversion efficiency of the first-stage processing device.

[0005] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides an engine emission control method, which includes: obtaining the first-stage oxygen storage amount after being processed by the first-stage processing device in the previous driving cycle of the engine; and in the current driving cycle, by judging whether the first-stage oxygen storage amount exceeds a preset threshold, determining whether to use the first-stage measurement data processed by the first-stage processing device or the second-stage measurement data processed by the second-stage processing device to correct the air-fuel ratio, thereby realizing the control of the gas emissions processed by the dual-stage processing device.

[0006] Optionally, the first-stage processing device and / or the second-stage processing device is a three-way catalytic converter.

[0007] Optionally, the second-stage measurement data is a voltage value indicating the oxygen content of the exhaust gas, which is obtained by the oxygen sensor at the outlet of the second-stage processing device. The method of using the second-stage measurement data processed by the second-stage processing device to correct the air-fuel ratio includes: obtaining the second-stage voltage value; calculating the difference between the second-stage voltage value and the preset voltage value; and converting the calculated difference between the second-stage voltage value and the preset voltage value into the air-fuel ratio that needs to be corrected through a PID control function.

[0008] Optionally, the first-stage measurement data is a voltage value indicating the oxygen content of the exhaust gas, which is obtained by an oxygen sensor at the outlet of the first-stage processing device. The method of using the first-stage measurement data processed by the first-stage processing device to correct the air-fuel ratio includes: obtaining the first-stage voltage value; calculating the difference between the first-stage voltage value and a preset voltage value; and converting the calculated difference between the first-stage voltage value and the preset voltage value into an air-fuel ratio that needs to be corrected through a PID control function.

[0009] Optionally, after determining whether the first-stage oxygen storage capacity exceeds a preset threshold, the engine emission control method further includes: detecting whether the oxygen sensor can work normally; and when the oxygen sensor can work normally, executing the step of correcting the air-fuel ratio using the first-stage measurement data processed by the first-stage processing device or correcting the air-fuel ratio using the second-stage measurement data processed by the second-stage processing device.

[0010] An embodiment of the present invention further provides an engine control unit, which includes: a memory storing a program that can be run on a processor; and the processor, which is configured to implement the above-mentioned engine emission control method when executing the program.

[0011] An embodiment of the present invention further provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute the above-mentioned engine emission control method.

[0012] The embodiment of the present invention also provides an emission system of a vehicle engine, which includes a first oxygen sensor, a first-stage processing device, a second oxygen sensor, a second-stage processing device, and a third oxygen sensor in order according to the direction of the exhaust gas, and the emission system of the vehicle engine also includes the above-mentioned engine control unit. The first oxygen sensor is used to detect the air-fuel ratio entering the emission system, the first-stage processing device is used to process the exhaust gas, the second oxygen sensor is used to obtain the first-stage measurement data processed by the first-stage processing device, the second-stage processing device is used to process the exhaust gas, and the third oxygen sensor is used to obtain the second-stage measurement data processed by the second-stage processing device.

[0013] Optionally, the first-stage processing device and / or the second-stage processing device is a three-way catalytic converter.

[0014] An embodiment of the present invention further provides a vehicle, comprising the above-mentioned engine control unit and the above-mentioned emission system of the vehicle engine.

[0015] Through the above technical solution, in the application of the vehicle using a two-stage treatment device (for example, a natural gas two-stage three-way catalytic post-treatment system) to treat exhaust gas, when the post-treatment conversion efficiency of the first-stage treatment device is reduced, the post-treatment conversion capacity of the second-stage treatment device can be fully utilized, thereby increasing the durability of the post-treatment. The embodiment of the present invention can more accurately control gas emissions and can reduce the precious metal content of the post-treatment to a greater extent while meeting the requirements of emission durability.

[0016] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0018] Figure 1 is a flow chart of an engine emission control method provided by an embodiment of the present invention;

[0019] Figure 2 is a flow diagram of an example engine emissions control method; and

[0020] Figure 3 It is a schematic diagram of the structure of an exhaust system of a vehicle engine provided by an embodiment of the present invention.

[0021] Description of Reference Numerals

[0022] 1First oxygen sensor 2First stage processing device

[0023] 3 Second oxygen sensor 4 Second stage processing device

[0024] 5Third oxygen sensor DETAILED DESCRIPTION

[0025] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0026] Figure 1 is a flow chart of the engine emission control method provided by an embodiment of the present invention, please refer to Figure 1 , the engine emission control method may include the following steps:

[0027] Step S110: obtaining the first-stage oxygen storage amount processed by the first-stage processing device in the last driving cycle of the engine.

[0028] In the embodiment of the present invention, the first-stage processing device and / or the second-stage processing device is preferably a three-way catalytic converter.

[0029] Among them, a driving cycle can be understood as the process from starting the vehicle switch, running the engine to stopping the vehicle (turning off the engine). In the application of natural gas two-stage three-way catalytic post-treatment, for example, the degradation of the post-treatment of the first-stage treatment device is faster than that of the second-stage treatment device. Therefore, in each driving cycle, the embodiment of the present invention monitors the first-stage oxygen storage after the treatment of the first-stage treatment device.

[0030] Preferably, the embodiment of the present invention can obtain the first-stage voltage value after processing by the first-stage processing device through a narrow-band oxygen sensor arranged at the outlet of the first-stage processing device; and then calculate the first-stage oxygen storage capacity after processing by the first-stage processing device through the exhaust flow rate, the air-fuel ratio measured at the inlet of the first-stage processing device and the first-stage voltage value.

[0031] Step S120: In the current driving cycle, by judging whether the first-stage oxygen storage capacity exceeds a preset threshold, it is determined whether to use the first-stage measurement data processed by the first-stage processing device to correct the air-fuel ratio or to use the second-stage measurement data processed by the second-stage processing device to correct the air-fuel ratio, thereby achieving control of gas emissions processed by the dual-stage processing device.

[0032] In the embodiment of the present invention, before the post-processing of the first-stage treatment device deteriorates to a certain extent, the air-fuel ratio correction can be performed through the first-stage measurement data obtained from the outlet of the first-stage post-processing device; when the post-processing of the first-stage treatment device deteriorates to a certain extent, the input of the post-oxygen closed-loop correction is changed from the first-stage measurement data after the first-stage treatment device to the second-stage measurement data of the second stage (treatment device), so as to make full use of the conversion efficiency of the second-stage treatment device, thereby increasing the durability performance of the post-processing and emissions.

[0033] Preferably, in step S120, the second-level measurement data is a voltage value indicating the oxygen content of the exhaust gas, which is obtained by the oxygen sensor at the outlet of the second-level processing device, and the second-level measurement data processed by the second-level processing device is used to correct the air-fuel ratio, including: obtaining the second-level voltage value; calculating the difference between the second-level voltage value and the preset voltage value; and converting the calculated difference between the second-level voltage value and the preset voltage value into the air-fuel ratio that needs to be corrected through a PID control function.

[0034] Preferably, in step S120, the first-level measurement data is a voltage value indicating the oxygen content of the exhaust gas, which is obtained by the oxygen sensor at the outlet of the first-level processing device, and the first-level measurement data processed by the first-level processing device is used to correct the air-fuel ratio, including: obtaining the first-level voltage value; calculating the difference between the first-level voltage value and the preset voltage value; and converting the calculated difference between the first-level voltage value and the preset voltage value into the air-fuel ratio that needs to be corrected through a PID control function.

[0035] Please refer to Figure 2 For example, when it is detected that the first-stage oxygen storage amount of the first-stage post-processing in the previous driving cycle is higher than the preset threshold or limit value, in the current driving cycle, for example, through the narrow-band oxygen sensor arranged after the first-stage processing device, the first-stage voltage value indicating the oxygen content of the exhaust gas after the first-stage processing device is obtained; the difference between the first-stage voltage value and the preset voltage value is calculated; and through the PID control function, the difference between the calculated first-stage voltage value and the preset voltage value is converted into the air-fuel ratio that needs to be corrected. That is, the first-stage measurement data processed by the first-stage processing device is used to perform correction control of the air-fuel ratio. When it is detected that the first-stage oxygen storage amount of the first-stage post-processing in the previous driving cycle is lower than a preset threshold or limit, in the current driving cycle, the first-stage measurement data processed by the first-stage processing device is no longer used to perform correction control of the air-fuel ratio, but the second-stage measurement data processed by the second-stage processing device is used to perform correction control of the air-fuel ratio, including: for example, obtaining a second-stage voltage value through a narrow-band oxygen sensor arranged after the second-stage processing device; calculating the difference between the actual voltage value and the preset voltage value; and converting the calculated difference between the second-stage voltage value and the preset voltage value into the air-fuel ratio that needs to be corrected through a PID control function.

[0036] Preferably, after determining whether the first-stage oxygen storage capacity exceeds a preset threshold, the engine emission control method further includes: detecting whether the oxygen sensor can work normally; and when the oxygen sensor can work normally, executing the step of correcting the air-fuel ratio using the first-stage measurement data processed by the first-stage processing device or correcting the air-fuel ratio using the second-stage measurement data processed by the second-stage processing device.

[0037] Please continue to refer to Figure 2 At the beginning of the current driving cycle, after the engine is running, it is possible to detect whether the oxygen sensor (e.g., narrow-band oxygen sensor) arranged after the first-stage processing device and the second-stage processing device can work normally. Only when the oxygen sensor is normal can the post-oxygen closed-loop correction be satisfied. When the oxygen sensor is abnormal, it is necessary to repair or replace the oxygen sensor first, and then perform the post-oxygen closed-loop correction control.

[0038] Accordingly, in the application of the embodiment of the present invention in which the vehicle treats the exhaust gas through a two-stage treatment device (for example, a natural gas two-stage three-way catalytic post-treatment system), when the post-treatment conversion efficiency of the first-stage treatment device is reduced, the post-treatment conversion capacity of the second-stage treatment device can be fully utilized, thereby increasing the durability of the post-treatment. The embodiment of the present invention can also more accurately control gas emissions, and can reduce the precious metal content of the post-treatment to a greater extent while meeting the requirements of emission durability.

[0039] An embodiment of the present invention further provides an engine control unit, which includes: a memory storing a program that can be run on a processor; and the processor, which is configured to implement the above-mentioned engine emission control method when executing the program.

[0040] The engine control unit is, for example, an electronic control unit (ECU), also known as a "vehicle computer".

[0041] An embodiment of the present invention further provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute the above-mentioned engine emission control method.

[0042] Figure 3 is a schematic diagram of the structure of the exhaust system of the vehicle engine provided by the embodiment of the present invention, please refer to Figure 3 The vehicle engine exhaust system includes, in order of exhaust gas direction, a first oxygen sensor 1, a first-stage processing device 2, a second oxygen sensor 3, a second-stage processing device 4, and a third oxygen sensor 5. The vehicle engine exhaust system also includes an engine control unit as claimed in claim 6 (not shown in the figure).

[0043] Among them, the first oxygen sensor 1 is used to detect the air-fuel ratio entering the emission system, the first-stage processing device 2 is used to process the exhaust gas, the second oxygen sensor 3 is used to obtain the first-stage measurement data processed by the first-stage processing device, the second-stage processing device 4 is used to process the exhaust gas, and the third oxygen sensor 5 is used to obtain the second-stage measurement data processed by the second-stage processing device.

[0044] The first oxygen sensor 1 is, for example, a wide-band oxygen sensor, which can directly obtain the air-fuel ratio entering the exhaust system; the second oxygen sensor 3 and the third oxygen sensor 5 are, for example, narrow-band oxygen sensors, which obtain voltage values ​​indicating the oxygen content of the exhaust gas.

[0045] Preferably, in the last driving cycle of the engine, the second oxygen sensor 3 detects the first-stage voltage value, and the engine control unit is further used to calculate the first-stage oxygen storage amount after the first-stage treatment device processes through the exhaust flow, the air-fuel ratio measured at the inlet of the first-stage treatment device, and the first-stage voltage value. In the embodiment of the present invention, the first-stage treatment device 2 and / or the second-stage treatment device 4 are preferably three-way catalytic converters.

[0046] For example, when the first-stage oxygen storage amount of the first-stage post-processing of the previous driving cycle is detected by the second oxygen sensor 3 to be higher than the preset threshold or limit value, in the current driving cycle, the first-stage voltage value is obtained by the second oxygen sensor 3; the difference between the first-stage voltage value and the preset voltage value is calculated; and the difference between the calculated first-stage voltage value and the preset voltage value is converted into the air-fuel ratio that needs to be corrected through the PID control function. That is, the first-stage measurement data processed by the first-stage processing device 2 is used to perform the correction control of the air-fuel ratio. When the first-stage oxygen storage amount of the first-stage post-processing of the previous driving cycle is detected by the second oxygen sensor 3 to be lower than the preset threshold or limit value, in the current driving cycle, the first-stage measurement data processed by the first-stage processing device 2 is no longer used to perform the correction control of the air-fuel ratio, but the second-stage measurement data processed by the second-stage processing device 4 is used to perform the correction control of the air-fuel ratio, including: obtaining the second-stage voltage value through the third oxygen sensor 5; calculating the difference between the second-stage voltage value and the preset voltage value; and converting the difference between the calculated second-stage voltage value and the preset voltage value into the air-fuel ratio that needs to be corrected through the PID control function.

[0047] In the embodiment of the present invention, before the post-treatment of the first-stage treatment device deteriorates to a certain degree, the air-fuel ratio correction can be performed through the post-oxygen voltage value obtained at the outlet of the first-stage post-treatment device; when the post-treatment of the first-stage treatment device deteriorates to a certain degree, the input of the post-oxygen closed-loop correction is changed from the post-oxygen voltage value of the first-stage treatment device to the post-oxygen voltage value of the second-stage treatment device, so as to make full use of the conversion efficiency of the post-treatment of the second-stage treatment device, thereby increasing the durability of the post-treatment and emissions, and providing a guarantee for reducing the precious metal content of the post-treatment.

[0048] An embodiment of the present invention further provides a vehicle, comprising the above-mentioned engine control unit and the above-mentioned emission system of the vehicle engine.

[0049] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0050] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0051] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0052] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0053] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0054] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0055] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0056] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0057] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. An engine emission control method, characterized in that: The engine emission control method comprises: Obtaining the first-stage oxygen storage amount after being processed by the first-stage processing device in the last driving cycle of the engine; and In the current driving cycle, by judging whether the first-stage oxygen storage capacity exceeds a preset threshold, it is determined whether to use the first-stage measurement data processed by the first-stage processing device or the second-stage measurement data processed by the second-stage processing device to correct the air-fuel ratio, thereby achieving control of gas emissions processed by the dual-stage processing device.

2. The engine emission control method according to claim 1, characterized in that: The first-stage processing device and / or the second-stage processing device is a three-way catalytic converter.

3. The engine emission control method according to claim 1, characterized in that: The second-stage measurement data is a voltage value indicating the oxygen content of the exhaust gas obtained by the oxygen sensor at the outlet of the second-stage processing device. The second-stage measurement data processed by the second-stage processing device is used to correct the air-fuel ratio, including: Get the second level voltage value; calculating a difference between the second level voltage value and a preset voltage value; and Through the PID control function, the difference between the calculated second-stage voltage value and the preset voltage value is converted into the air-fuel ratio that needs to be corrected.

4. The engine emission control method according to claim 1, characterized in that: The first-stage measurement data is a voltage value indicating the oxygen content of the exhaust gas obtained by the oxygen sensor at the outlet of the first-stage processing device. The first-stage measurement data processed by the first-stage processing device is used to correct the air-fuel ratio, including: Get the first level voltage value; Calculating a difference between the first level voltage value and a preset voltage value; and Through the PID control function, the calculated difference between the first-stage voltage value and the preset voltage value is converted into the air-fuel ratio that needs to be corrected.

5. The engine emission control method according to claim 1, characterized in that: After determining whether the first-stage oxygen storage capacity exceeds a preset threshold, the engine emission control method further includes: Check whether the oxygen sensor is working properly; and When the oxygen sensor can work normally, the step of correcting the air-fuel ratio by using the first-stage measurement data processed by the first-stage processing device or the step of correcting the air-fuel ratio by using the second-stage measurement data processed by the second-stage processing device is performed.

6. An engine control unit, characterized in that: The engine control unit comprises: a memory storing a program that can be executed on the processor; and The processor is configured to implement the engine emission control method according to any one of claims 1 to 5 when executing the program.

7. A machine-readable storage medium, characterized in that: The machine-readable storage medium stores instructions for enabling a machine to execute the engine emission control method described in any one of claims 1 to 5.

8. An exhaust system for a vehicle engine, characterized in that: The vehicle engine exhaust system includes a first oxygen sensor, a first-stage processing device, a second oxygen sensor, a second-stage processing device, and a third oxygen sensor in order according to the direction of the exhaust gas. The vehicle engine exhaust system also includes the engine control unit according to claim 6. The first oxygen sensor is used to detect the air-fuel ratio entering the exhaust system. The first stage treatment device is used to treat the exhaust gas, The second oxygen sensor is used to obtain the first-stage measurement data processed by the first-stage processing device, The second stage treatment device is used to treat the exhaust gas, The third oxygen sensor is used to obtain the second-stage measurement data processed by the second-stage processing device.

9. The exhaust system of a vehicle engine according to claim 8, characterized in that: The first-stage processing device and / or the second-stage processing device is a three-way catalytic converter.

10. A vehicle, characterized in that: The vehicle comprises the engine control unit of claim 6 and the exhaust system of the vehicle engine of claim 8 or 9.

Images