Engine speed control method, engine control unit, storage medium and vehicle

Abstract

The embodiment of the invention provides an engine rotating speed control method, an engine control unit, a storage medium and a vehicle, and belongs to the technical field of diesel engines. The control method comprises the steps that when the diesel engine vehicle is in a parking regeneration working condition, an engine is controlled to operate at a first rotating speed, and the temperature of an inlet of a post-processing system rises; after the engine operates for a period of time, the monitoring temperature of an inlet of the aftertreatment system and the conversion efficiency of the aftertreatment system are obtained; and the rotating speed of the engine is controlled according to the obtained monitoring temperature and conversion efficiency. According to the embodiment of the invention, the monitoring temperature of the inlet of the post-processing system and the conversion efficiency of the post-processing system are monitored in real time, and when the temperature of the inlet of the post-processing system has enough temperature margin and the DOC efficiency is normal, the rotating speed of the engine is properly reduced so as to reduce the fuel consumption of parking regeneration; on the contrary, the rotating speed of the engine is properly increased to ensure that parking regeneration is smoothly completed.

Description

Technical Field

[0001] This invention relates to the field of diesel engine technology, and more specifically to a method for controlling engine speed, an engine control unit, a storage medium, and a vehicle. Background Technology

[0002] Diesel vehicles can restore their aftertreatment performance through regeneration to meet emission requirements. The most common regeneration method is parking regeneration, where the vehicle is parked and the parking regeneration function is activated. Parking regeneration is necessary in situations such as when the vehicle is being repaired at a service station, when driving poses a safety risk to regeneration, when regeneration cannot be completed while driving, or when there is a high level of carbon buildup in the aftertreatment system. To ensure that the aftertreatment inlet reaches the hydrocarbon (HC) ignition temperature during parking regeneration, the engine idle speed needs to be increased to improve the engine's thermal management capabilities.

[0003] In existing technologies, the parking regeneration speed is set to a fixed value or adjusted in an open-loop manner based on ambient temperature and altitude. The disadvantages of existing technologies include: 1) Higher engine idle speeds result in higher engine thermal management capabilities but also higher fuel consumption during parking regeneration; some products experience increased noise at higher speeds near the parking regeneration speed. 2) Lower engine idle speeds for parking regeneration lead to lower engine thermal management capabilities, potentially causing excessively long preheating times or regeneration failure in extremely cold environments or when DOC performance deteriorates. 3) To ensure the aftertreatment inlet reaches the HC ignition temperature under various conditions, higher engine idle speeds are required to maintain sufficient margin in the aftertreatment inlet temperature, which necessitates additional fuel consumption for parking regeneration. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling the speed of a diesel engine. This method can actively adjust the engine speed under parking regeneration conditions to save fuel consumption.

[0005] To achieve the above objectives, embodiments of the present invention provide a method for controlling the speed of a diesel engine. The method includes: when the diesel vehicle is in a parking regeneration condition, controlling the engine to run at a first speed to increase the temperature at the inlet of the aftertreatment system; after the engine has been running for a period of time, acquiring the monitoring temperature at the inlet of the aftertreatment system and the conversion efficiency of the aftertreatment system; and controlling the speed of the engine based on the acquired monitoring temperature and conversion efficiency.

[0006] Optionally, controlling the engine speed based on the acquired monitoring temperature and conversion efficiency includes: controlling the engine speed to decrease when the monitoring temperature exceeds an upper limit temperature threshold and the conversion efficiency exceeds a preset conversion efficiency threshold; and controlling the engine speed to increase when the monitoring temperature is lower than a lower limit temperature threshold or the conversion efficiency is lower than the preset conversion efficiency threshold, wherein the upper limit temperature threshold is greater than the lower limit temperature threshold.

[0007] Optionally, the method for controlling the diesel engine speed further includes: determining the preset conversion efficiency threshold based on the leakage limit of the aftertreatment system.

[0008] Optionally, the method for controlling the diesel engine speed further includes: determining the upper limit temperature threshold and the lower limit temperature threshold based on the inlet temperature and conversion efficiency required for the aftertreatment system to operate normally.

[0009] Optionally, controlling the engine speed further includes: determining the correspondence between the engine speed change and the temperature change at the inlet of the aftertreatment system based on the engine's thermal management capability; and determining the magnitude of the engine speed reduction or increase based on the determined correspondence between the engine speed change and the temperature change at the inlet of the aftertreatment system, so as to control the engine speed reduction or increase.

[0010] Optionally, controlling the engine speed further includes: determining the temperature change step size of the inlet of the aftertreatment system corresponding to a unit speed change of the engine based on the engine's thermal management capability; and gradually controlling the engine speed to decrease or increase based on the temperature change step size and the unit speed change.

[0011] Optionally, the method for controlling the speed of a diesel engine further includes: setting an upper speed threshold and a lower speed threshold for the engine speed to control the engine speed between the upper speed threshold and the lower speed threshold, wherein the upper speed threshold and the lower speed threshold are determined based on the engine's thermal management capability and the noise and vibration requirements of the aftertreatment system, and the upper speed threshold is greater than the lower speed threshold.

[0012] This invention also provides an engine control unit, the engine control unit comprising: a memory storing a program executable on a processor; and the processor configured to implement the above-described method for controlling the speed of a diesel engine when executing the program.

[0013] This invention also provides a machine-readable storage medium storing instructions for causing a machine to execute the aforementioned control method for diesel engine speed.

[0014] This invention also provides a vehicle, which includes the engine control unit and after-treatment system described above.

[0015] Through the above technical solution, in this embodiment of the invention, when a diesel vehicle is in parking regeneration mode, the engine is controlled to run at a first speed to raise the temperature of the aftertreatment system inlet. After the engine has been running for a period of time, the monitoring temperature of the aftertreatment system inlet and the conversion efficiency of the aftertreatment system are obtained. Based on the obtained monitoring temperature and conversion efficiency, the engine speed is controlled. This embodiment of the invention monitors the monitoring temperature of the aftertreatment system inlet (aftertreatment inlet temperature) and the conversion efficiency of the aftertreatment system in real time. When the aftertreatment inlet temperature has sufficient temperature margin and the DOC efficiency is normal, the engine speed is appropriately reduced to reduce fuel consumption during parking regeneration; conversely, the engine speed is appropriately increased to ensure smooth completion of parking regeneration. This embodiment of the invention can actively adjust the engine speed during parking regeneration mode to save fuel consumption.

[0016] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 This is a flowchart illustrating a method for controlling the speed of a diesel engine provided in an embodiment of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0020] Figure 1 This is a flowchart illustrating the method for controlling the speed of a diesel engine provided in an embodiment of the present invention. Please refer to it. Figure 1 The method for controlling the speed of a diesel engine may include the following steps:

[0021] Step S110: When the diesel vehicle is in parking regeneration mode, control the engine to run at the first speed to raise the temperature of the inlet of the aftertreatment system.

[0022] When a diesel vehicle enters the parking regeneration mode, engine control can be divided into two stages. The first stage is the initial stage of parking regeneration, which involves open-loop control of the engine speed to rapidly increase the temperature at the inlet of the aftertreatment system (also known as the aftertreatment inlet temperature). Taking a diesel oxidation catalyst (DOC) as an example of the aftertreatment system, the engine is controlled to run at a first speed to rapidly increase the temperature at the inlet of the aftertreatment system.

[0023] In this embodiment of the invention, the setting of the first speed is as follows: For example, during the development stage of diesel engine vehicles, the aftertreatment inlet temperature is usually set to be between 350°C and 400°C when the vehicle is in parking regeneration mode; for example, the first speed of the open-loop stage is selected when the aftertreatment inlet temperature can reach, for example, 380°C under idle load.

[0024] It should be noted that setting the first rotation speed, for example, to 1700 rpm, is to rapidly increase the inlet temperature of the post-processing. However, in this embodiment of the invention, it is not necessary to increase the inlet temperature of the post-processing to 380°C during the initial stage of parking regeneration.

[0025] Step S120: After the engine has been running for a period of time, obtain the monitoring temperature of the inlet of the aftertreatment system and the conversion efficiency of the aftertreatment system.

[0026] Following on from the previous section, when a diesel vehicle enters the parking regeneration mode, the second stage of engine control involves closed-loop control of the engine speed. For example, after the engine has been running for a period of time, i.e., upon entering the second stage, the aftertreatment inlet temperature (i.e., the monitoring temperature) and the aftertreatment system's conversion efficiency are acquired in real time. For instance, the monitoring temperature can be acquired in real time using a temperature sensor located before the DOC. Alternatively, the aftertreatment outlet temperature can be acquired in real time using a temperature sensor located after the DOC. The conversion efficiency of the DOC is then determined by the difference between the aftertreatment outlet temperature and the aftertreatment inlet temperature, along with the heat of the injected fuel. It should be noted that this embodiment of the invention does not limit the method of acquiring the monitoring temperature and the aftertreatment system's conversion efficiency.

[0027] Step S130: Control the engine speed based on the acquired monitored temperature and conversion efficiency.

[0028] Preferably, step S130 may include: controlling the engine speed to decrease when the monitored temperature exceeds an upper temperature threshold and the conversion efficiency exceeds a preset conversion efficiency threshold; and controlling the engine speed to increase when the monitored temperature is lower than a lower temperature threshold or the conversion efficiency is lower than the preset conversion efficiency threshold. Wherein, the upper temperature threshold is greater than the lower temperature threshold.

[0029] Following the above example, this embodiment of the invention monitors the aftertreatment inlet temperature and the conversion efficiency of the aftertreatment system in real time. When the aftertreatment inlet temperature has sufficient temperature margin and the DOC efficiency is normal, the engine speed is appropriately reduced to decrease fuel consumption during parking regeneration; conversely, the engine speed is appropriately increased to ensure smooth completion of parking regeneration. For example, when the aftertreatment inlet temperature rises to a suitable range (e.g., exceeding the upper temperature threshold, which is, for example, 320°C), and the conversion efficiency of hydrocarbons (HC) within the DOC is within a reasonable range (e.g., exceeding a preset conversion efficiency threshold, which is, for example, 50%), the engine speed is appropriately reduced, i.e., the engine speed is controlled to decrease. When the aftertreatment inlet temperature is below a suitable range (e.g., below the lower temperature threshold, which is, for example, 300°C) or the conversion efficiency within the DOC is below a reasonable range (e.g., below 50%), the engine speed is appropriately increased, i.e., the engine speed is controlled to increase. This enables closed-loop control of the post-processing inlet temperature (e.g., between 300°C and 320°C).

[0030] Preferably, the method for controlling the diesel engine speed may further include: determining the preset conversion efficiency threshold based on the leakage limit of the aftertreatment system.

[0031] For example, the HC conversion efficiency threshold of DOC can be preset based on the HC leakage (development) limit of DOC. For instance, if the HC conversion efficiency is lower than 60%, the HC leakage of DOC will exceed the leakage (development) limit (e.g., 2000 ppm). Therefore, the HC conversion efficiency threshold can be preset to 60%.

[0032] Preferably, the method for controlling the diesel engine speed may further include: determining the upper limit temperature threshold and the lower limit temperature threshold based on the inlet temperature and conversion efficiency required for the aftertreatment system to operate normally.

[0033] As illustrated by the example, under normal HC conversion efficiency of DOC, upper and lower temperature thresholds can be preset according to the DOC capacity, i.e., the closed-loop control of the post-processing inlet temperature range. For example, the DOC post-processing inlet temperature typically operates normally when it is above 280°C, or when the HC conversion efficiency is above 80%. In this embodiment of the invention, a 20°C control margin is preferably reserved; therefore, 300°C can be set as the lower temperature threshold for closed-loop control of the post-processing inlet temperature, and 320°C as the upper temperature threshold.

[0034] Preferably, step S130 may further include: determining the correspondence between the engine speed change and the temperature change at the inlet of the aftertreatment system based on the engine's thermal management capability; and determining the magnitude of the engine speed reduction or increase based on the determined correspondence between the engine speed change and the temperature change at the inlet of the aftertreatment system, so as to control the engine speed reduction or increase.

[0035] For example, the magnitude of engine speed adjustment (both downward and upward) can be preset (or calibrated) based on the differences in thermal management capabilities corresponding to different engine speeds. For instance, for speed changes during parking regeneration, there is a 40-degree difference in engine thermal management capability for every 100 rpm, a 35-degree difference for every 90 rpm, a 25-degree difference for every 80 rpm, a 15-degree difference for every 70 rpm, and so on. Based on this, the correspondence between engine speed changes and aftertreatment system inlet temperature changes can be determined. Furthermore, a curve showing the correspondence between engine speed changes and aftertreatment system inlet temperature changes can be plotted through data fitting; based on this curve and the acquired monitored temperature, the magnitude of engine speed adjustment (both downward and upward) can be determined.

[0036] Preferably, step S130 may further include: determining the temperature change step size of the inlet of the aftertreatment system corresponding to the unit speed change of the engine based on the engine's thermal management capability; and gradually controlling the engine speed to decrease or increase based on the temperature change step size and the unit speed change.

[0037] To illustrate, the magnitude of engine speed adjustment (both downward and upward) can be preset (or calibrated) based on the differences in thermal management capabilities corresponding to different engine speeds. For example, for speed changes during parking regeneration, there is a 40° difference in engine thermal management capability for every 100 rpm. Therefore, when the aftertreatment inlet temperature exceeds the upper limit temperature threshold by 40° (e.g., the aftertreatment inlet temperature is 360°), the engine speed is reduced by 100 rpm. Since there is a certain transition period for engine thermal management capability after speed change, the engine speed is adjusted and stabilized for a period of time (e.g., preset 30 seconds). If the aftertreatment inlet temperature is still higher than 320°, the engine speed is adjusted again, for example, reduced by 100 rpm.

[0038] Preferably, step S130 may further include: setting an upper speed threshold and a lower speed threshold for the engine to control the engine speed between the upper speed threshold and the lower speed threshold. The upper speed threshold and the lower speed threshold are determined based on the engine's thermal management capabilities and the noise and vibration requirements of the aftertreatment system, wherein the upper speed threshold is greater than the lower speed threshold.

[0039] For example, when a diesel vehicle is in an extreme environment (e.g., extremely cold or extremely hot), and when the vehicle enters parking regeneration mode, continuously controlling the engine speed to decrease or increase may not achieve a suitable aftertreatment inlet temperature (e.g., between 300°C and 320°C). In this case, upper and lower speed thresholds can be set for the engine speed to control the engine speed between the upper and lower speed thresholds.

[0040] Furthermore, embodiments of the present invention also provide a method for setting an upper limit speed threshold and a lower limit speed threshold for the engine speed. For example, during the engine development stage, after the engine speed reaches 2000 rpm, the thermal management capability basically no longer improves, and the noise and vibration requirements can be met. Therefore, 2000 rpm can be set as the upper limit speed threshold. During the development stage, when the engine speed is below 1100 rpm, the noise and vibration increase significantly. Therefore, 1200 rpm can be set as the lower limit speed threshold.

[0041] Accordingly, in this embodiment of the invention, when a diesel vehicle is in parking regeneration mode, the engine is controlled to run at a first speed to raise the temperature at the inlet of the aftertreatment system. After the engine has been running for a period of time, the monitoring temperature at the inlet of the aftertreatment system and the conversion efficiency of the aftertreatment system are acquired. Based on the acquired monitoring temperature and conversion efficiency, the engine speed is controlled. This embodiment of the invention monitors the monitoring temperature at the inlet of the aftertreatment system (aftertreatment inlet temperature) and the conversion efficiency of the aftertreatment system in real time. When the aftertreatment inlet temperature has sufficient temperature margin and the DOC efficiency is normal, the engine speed is appropriately reduced to decrease fuel consumption during parking regeneration; conversely, the engine speed is appropriately increased to ensure smooth completion of parking regeneration. This embodiment of the invention can actively adjust the engine speed during parking regeneration to save fuel consumption. Verification has shown that parking regeneration fuel consumption for different vehicle models can be reduced by 20% to 40%, reducing customer costs and improving customer reputation.

[0042] This invention also provides an engine control unit, which may include: a memory storing a program executable on a processor; and the processor configured to implement the aforementioned method for controlling the speed of a diesel engine when executing the program.

[0043] This invention also provides a machine-readable storage medium storing instructions for causing a machine to execute the aforementioned control method for diesel engine speed.

[0044] This invention also provides a vehicle, which includes the engine control unit and after-treatment system described above.

[0045] The engine control unit is, for example, the Engine Control Unit (ECU). The aftertreatment system is, for example, a diesel oxidation catalyst (DOC).

[0046] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0047] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0048] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0049] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0050] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0051] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0052] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, 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 technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0053] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0054] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for controlling the speed of a diesel engine, characterized in that, The method for controlling the speed of a diesel engine includes: When a diesel vehicle is in parking regeneration mode, the engine is controlled to run at the first speed to raise the temperature at the inlet of the aftertreatment system. After the engine has been running for a period of time, the monitoring temperature at the inlet of the aftertreatment system and the conversion efficiency of the aftertreatment system are obtained; and The engine speed is controlled based on the acquired monitored temperature and conversion efficiency.

2. The method for controlling the speed of a diesel engine according to claim 1, characterized in that, The step of controlling the engine speed based on the acquired monitored temperature and conversion efficiency includes: When the monitored temperature exceeds the upper temperature threshold and the conversion efficiency exceeds the preset conversion efficiency threshold, the engine speed is controlled to decrease; and When the monitored temperature is lower than the lower limit temperature threshold or the conversion efficiency is lower than the preset conversion efficiency threshold, the engine speed is controlled to increase. The upper temperature threshold is greater than the lower temperature threshold.

3. The method for controlling the speed of a diesel engine according to claim 2, characterized in that, The method for controlling the speed of a diesel engine also includes: The preset conversion efficiency threshold is determined based on the leakage limit of the post-processing system.

4. The method for controlling the speed of a diesel engine according to claim 2, characterized in that, The method for controlling the speed of a diesel engine also includes: The upper temperature threshold and the lower temperature threshold are determined based on the inlet temperature and conversion efficiency required for the post-processing system to operate normally.

5. The method for controlling the speed of a diesel engine according to claim 2, characterized in that, The control of the engine speed also includes: Based on the engine's thermal management capabilities, determine the correspondence between changes in engine speed and changes in the inlet temperature of the aftertreatment system; and Based on the established correspondence between the engine speed change and the temperature change at the inlet of the aftertreatment system, the magnitude of the engine speed reduction or increase is determined to control the engine speed reduction or increase.

6. The method for controlling the speed of a diesel engine according to claim 2, characterized in that, The control of the engine speed also includes: Based on the engine's thermal management capabilities, determine the temperature change step size at the inlet of the aftertreatment system corresponding to a unit speed change of the engine; and Based on the temperature change step size, the engine speed is gradually controlled to decrease or increase by the unit speed change.

7. The method for controlling the speed of a diesel engine according to claim 1, characterized in that, The method for controlling the speed of a diesel engine also includes: Set an upper speed threshold and a lower speed threshold for the engine to control the engine speed between the upper speed threshold and the lower speed threshold. Specifically, based on the engine's thermal management capabilities and the noise and vibration requirements of the aftertreatment system, the upper speed threshold and the lower speed threshold are determined, wherein the upper speed threshold is greater than the lower speed threshold.

8. An engine control unit, characterized in that, The engine control unit includes: Memory, which stores programs that can run on a processor; and The processor is configured to implement the method for controlling the speed of a diesel engine as described in any one of claims 1-7 when executing the program.

9. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions for causing the machine to perform the control method for diesel engine speed as described in any one of claims 1-7.

10. A vehicle, characterized in that, The vehicle includes the engine control unit and after-treatment system as described in claim 8.

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