Control strategy for prolonging regeneration period of DPF (diesel particulate filter) of methanol-diesel dual-fuel engine

Abstract

The invention discloses a control strategy for prolonging the regeneration period of a diesel particulate filter (DPF) of a methanol-diesel dual-fuel engine. The control strategy comprises the following steps: S1, initializing an input condition; s2, an auxiliary regeneration threshold value is set, an input value is obtained, the input value is compared with the DPF carbon loading capacity reading M, and a first comparison result is obtained; s3, the minimum effective temperature threshold value T0 of DPF passive regeneration is set, T0 is compared with T, and a second comparison result is obtained; s4, the first comparison result and the second comparison result are comprehensively judged, and a DPF regeneration state instruction is generated; and S5, executing the DPF regeneration state instruction. A DPF regeneration strategy can be provided for the field of methanol diesel dual-fuel engines, and the blank in the prior art is filled; whether the DPF meets the auxiliary regeneration condition or not can be accurately known, auxiliary regeneration is started at the proper time, DPF regeneration is optimized, and the combustion efficiency of accumulated particulate matter of the DPF is improved; and extra NO2 generated by methanol combustion is effectively utilized and converted into DPF regeneration advantage.

Description

Technical Field

[0001] The invention relates to the field of DPF regeneration in a methanol-diesel dual-fuel engine, in particular to a control strategy for extending the DPF regeneration period in a methanol-diesel dual-fuel engine. Background Art

[0002] In line with the national dual-carbon strategy, low-carbon and zero-carbon fuels have been widely adopted in commercial vehicles. Methanol, a renewable green energy source with low manufacturing costs, is a key development direction for low-carbon fuels in commercial vehicles. However, methanol has a high flash point, making it difficult for pure methanol to stably burn under various operating conditions. Therefore, the current transportation market primarily utilizes methanol multi-fuel engines, with methanol-diesel dual-fuel engines accounting for the largest share.

[0003] Therefore, the existing technology designs methanol-diesel dual-fuel engines with the main purpose of solving methanol combustion, and does not give enough consideration to its subsequent emissions. New technologies have brought new challenges to the emissions of commercial vehicles.

[0004] To achieve compliance with PM and PN emissions, a diesel particulate filter (DPF) must be installed after the engine exhaust pipe. The DPF is a wall-flow structure with a closed end face. It captures exhaust particles through diffusion deposition, interception, and collision, reducing PM and PN emissions. As particles accumulate in the DPF, exhaust resistance increases, affecting the vehicle's power and fuel consumption. Therefore, when the DPF carbon accumulation reaches a certain level, it needs to be cleaned at high temperatures while the vehicle is driving. This process is called driving regeneration. Methanol injected into the cylinder absorbs a large amount of heat to vaporize. The exhaust temperature of a methanol-diesel dual-fuel engine is relatively low, and the DPF's auxiliary regeneration ability is weak, frequently triggering driving regeneration. Driving regeneration increases fuel consumption by approximately 50% compared to normal vehicle driving. Existing methanol-diesel dual-fuel vehicles still use the same driving regeneration cycle as traditional vehicles, and no specific strategy has been developed to extend the driving cycle based on the characteristics of methanol-diesel dual-fuel.

[0005] Although methanol can reduce carbon emissions as an alternative fuel, its combustion characteristics lead to new problems: (1) The combustion temperature of methanol is lower than that of diesel, which reduces the auxiliary regeneration efficiency; (2) The existing control strategy does not effectively utilize the additional NO2 generated by methanol combustion (the amount of NO2 generated by methanol combustion is 20%-30% higher than that of diesel), and fails to convert it into a DPF regeneration advantage.

[0006] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0007] The object of the present invention is to provide a control strategy for extending the DPF regeneration cycle of a methanol-diesel dual-fuel engine, which can solve the problems existing in the background technology.

[0008] To achieve the above object, the present invention provides a control strategy for extending the DPF regeneration cycle of a methanol-diesel dual-fuel engine, including the following steps: S1: Initialize the input conditions; S2: Set the auxiliary regeneration threshold, obtain the input value, compare the input value with the DPF carbon loading reading M, and obtain the first comparison result; S3: Set the minimum effective temperature threshold T0 for DPF passive regeneration, compare T0 with T, and obtain the second comparison result; S4: Make a comprehensive determination on the first comparison result and the second comparison result to generate a DPF regeneration status instruction; S5: Execute the DPF regeneration status instruction.

[0009] In one or more embodiments, the step S1 includes: S11: Real-time obtain the DPF carbon loading reading M of the engine controller; S12: Collect the actual temperature T of the DPF through a temperature sensor.

[0010] In one or more embodiments, the step S2 includes: S21: Set the carbon loading threshold M1 for the auxiliary regeneration mode and the driving regeneration trigger threshold M2, where M1 < M2; S22: Receive the input of the parameters M1 and M2 and synchronize them to the program; S23: Receive the input of the parameter M, compare M1, M2 and M, and confirm the first comparison result.

[0011] In one or more embodiments, the step S23 includes: S231: When both conditions are satisfied: M1 < M < M2, confirm that the first comparison result is that the carbon loading is compliant; S232: When either condition of M1 < M < M2 is not satisfied, confirm that the first comparison result is that the carbon loading is non-compliant.

[0012] In one or more embodiments, the step S3 includes: S31: Receive the input of the parameter T0; S32: Compare T with T0; S33: Obtain the second comparison result.

[0013] In one or more embodiments, the step S33 includes: S331: If T > T0 is satisfied, the second comparison result is that the temperature is compliant; S332: If T < T0, the second comparison result is that the temperature is non-compliant.

[0014] In one or more embodiments, the step S4 includes: S41: When the first comparison result is that the carbon loading is compliant and the second comparison result is that the temperature is compliant, the DPF regeneration status instruction is to trigger passive regeneration; S42: If the conditions corresponding to S41 are not satisfied, set the DPF regeneration status instruction to maintain the original control strategy;

[0015] In one or more embodiments, the step S5 includes: S51: if the DPF regeneration state instruction is to trigger passive regeneration, the engine enters the auxiliary regeneration mode; S52: if the DPF regeneration state instruction is to maintain the original control strategy, skip this step.

[0016] In one or more embodiments, in step S51, the steps performed by the auxiliary regeneration mode include: S511: in the engine development stage, a correction scheme is set based on the DPF carbon accumulation and the DPF temperature as input conditions; S512: according to the correction scheme, the real-time air-fuel ratio is calculated by the intake flow and the fuel flow, and the ratio of methanol and diesel is corrected according to the air-fuel ratio to obtain a methanol injection correction coefficient; S513: according to the correction scheme, the proportion of methanol combustion is increased until it meets the methanol injection correction coefficient.

[0017] Compared with the prior art, the multiple technical solutions and embodiments provided by the present invention have at least the following technical effects or advantages:

[0018] By providing a DPF regeneration strategy for the field of methanol-diesel dual-fuel engines, the gap in the existing technology that has not developed a special strategy to extend the driving cycle based on the characteristics of methanol-diesel dual fuel is filled; through the cross-judgment of temperature and accumulated carbon amount, it can accurately determine whether the auxiliary regeneration conditions are met, and start auxiliary regeneration at the right time, optimize DPF regeneration, and improve its accumulated particulate matter combustion efficiency; it can effectively utilize the extra NO2 generated by methanol combustion and convert it into a DPF regeneration advantage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and can be considered as illustrative of various combinations of preferred embodiments and do not constitute an undue limitation of the present invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of the overall flow of a control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine provided by the present invention. DETAILED DESCRIPTION

[0021] Unless otherwise expressly stated, throughout the specification and claims, the term "comprise" or its variations such as "include" or "comprising", "made of", etc. will be understood to include the stated elements or components but not to exclude other elements or other components.

[0022] The purpose of the present invention is to provide a DPF regeneration strategy for the field of methanol-diesel dual-fuel engines, and to optimize DPF regeneration and improve the combustion efficiency of its accumulated particulate matter.

[0023] Example 1:

[0024] To address the problem that the combustion temperature of methanol in a methanol-diesel engine is lower than that of diesel, which reduces the auxiliary regeneration efficiency; and to effectively utilize the additional NO2 generated by methanol combustion and convert it into a DPF regeneration advantage, this embodiment provides a control strategy for extending the DPF regeneration cycle in a methanol-diesel dual-fuel engine, including the following steps:

[0025] S1: Initialize input conditions;

[0026] As a preferred implementation of this embodiment, step S1 includes:

[0027] S11: obtaining a DPF carbon load reading M from an engine controller in real time;

[0028] S12: Collect the actual DPF temperature T through the temperature sensor.

[0029] Specifically, in order to obtain the carbon load and DPF temperature in real time, this application initializes the carbon load reading and the actual temperature, obtains synchronized information through sensor feedback, and then obtains accurate engine combustion and DPF status, and subsequently divides the control strategy according to the status.

[0030] S2: Setting an auxiliary regeneration threshold, obtaining an input value, and comparing the input value with the DPF carbon load reading M to obtain a first comparison result; wherein, the first comparison result can reflect the state of the DPF carbon load. This embodiment can use a higher priority authority to regulate the DPF regeneration logic based on the first comparison result.

[0031] As a preferred implementation of this embodiment, step S2 includes:

[0032] S21: Setting the auxiliary regeneration mode carbon load threshold M1 and the driving regeneration trigger threshold M2, where M1 <M2;

[0033] S22: Receive M1 and M2 parameter inputs and synchronize them to the program;

[0034] S23: Accept the input of the M parameter, compare M1, M2 and M, and confirm the first comparison result.

[0035] Specifically, in order to intervene in the appropriate DPF carbon loading state, make the DPF adapt to the characteristics of the methanol diesel engine, and perform reasonable regeneration, this embodiment selects the carbon loading target range. When the DPF carbon accumulation is large, this embodiment sets an auxiliary regeneration state, that is, a carbon loading range that the existing DPF regeneration strategy cannot take into account. This embodiment sets the first comparison result as one of the conditions for triggering auxiliary regeneration.

[0036] As a more preferred embodiment of this embodiment, step S1 includes:

[0037] S231: When it simultaneously satisfies: M1 < M < M2, confirm that the first comparison result is that the carbon loading meets the requirement;

[0038] S232: When it does not satisfy any of the conditions: M1 < M < M2, confirm that the first comparison result is that the carbon loading does not meet the requirement.

[0039] Specifically, when the DPF carbon loading is greater than the preset limit value of the assisted regeneration mode but has not reached the trigger value of the in - vehicle regeneration, one of the conditions for assisted regeneration is satisfied; otherwise, assisted regeneration is not satisfied, the system is in an activated state for a long time, and the regeneration trigger condition is judged according to the data in real time.

[0040] S3: Set the minimum effective temperature threshold T0 for DPF passive regeneration, compare T0 with T, and obtain the second comparison result.

[0041] As a preferred embodiment of this embodiment, step S3 includes:

[0042] S31: Accept the input of the T0 parameter;

[0043] S32: Compare T with T0;

[0044] S33: Obtain the second comparison result.

[0045] Specifically, when methanol is injected into the cylinder, it needs to absorb a large amount of heat for gasification. The exhaust temperature of the methanol - diesel dual - fuel engine is relatively low, and the DPF passive regeneration ability is weak, often triggering in - vehicle regeneration. Therefore, this embodiment sets the second comparison result as the second condition for triggering assisted regeneration, determines whether it is in an effective interval through temperature. When the temperature meets the requirement, it is used as a condition to enable assisted regeneration. When the exhaust temperature is relatively high, greater than the value at which DPF passive regeneration takes effect, the accumulated carbon in the DPF is in a state where passive regeneration can be carried out. At the same time, due to the high exhaust temperature, a large amount of methanol can burn normally.

[0046] As a preferred embodiment of this embodiment, step S33 includes:

[0047] S331: If T > T0 is satisfied, the second comparison result is that the temperature meets the requirement;

[0048] S332: If T < T0, the second comparison result is that the temperature does not meet the requirement.

[0049] S4: Make a comprehensive judgment on the first comparison result and the second comparison result, and generate a DPF regeneration status instruction;

[0050] As a preferred implementation of this embodiment, step S4 includes:

[0051] S41: If the first comparison result is that the carbon load meets the requirements and the second comparison result is that the temperature meets the requirements, the DPF regeneration state instruction is to trigger passive regeneration;

[0052] S42: If the corresponding condition of S41 is not met, the DPF regeneration state instruction is set to maintain the original control strategy.

[0053] Specifically, the first comparison result and the second comparison result are two triggering conditions for DPF assisted regeneration. When they are met at the same time, the system allows the assisted regeneration to be triggered, defines the control method of DPF regeneration of the dual-fuel engine, increases the proportion of methanol combustion, and after methanol combustion, produces more NO2, and the passive regeneration capacity of the DPF increases. NO2 reacts with the DPF's engine-generated carbon to become NO and CO2, and the DPF's carbon accumulation decreases rapidly and will not reach the driving regeneration trigger value, which can greatly extend the DPF driving regeneration cycle.

[0054] S5: Execute the DPF regeneration state instruction.

[0055] As a preferred implementation of this embodiment, step S5 includes:

[0056] S51: If the DPF regeneration state instruction is to trigger passive regeneration, the engine enters the auxiliary regeneration mode;

[0057] S52: If the DPF regeneration state instruction is to maintain the original control strategy, skip this step.

[0058] As a more preferred implementation of this embodiment, step S51 includes:

[0059] S511: During the engine development phase, a correction plan is set based on the DPF carbon accumulation and DPF temperature as input conditions;

[0060] S512: According to the correction scheme, a real-time air-fuel ratio is calculated using the intake air flow rate and the fuel flow rate, and the ratio of methanol to diesel is corrected based on the air-fuel ratio to obtain a methanol injection correction coefficient;

[0061] S513: According to the correction scheme, the proportion of methanol combustion is increased until the methanol injection correction coefficient is met.

[0062] Specifically, the real-time air-fuel ratio is calculated through the intake flow and fuel flow, and the ratio of methanol and diesel is corrected according to the air-fuel ratio to ensure that while the passive regeneration capacity is increased, the engine's stable combustion power output remains unchanged and does not affect the normal driving of the vehicle. This overall solves the problem that the methanol combustion temperature of the methanol diesel engine is lower than that of diesel, which reduces the auxiliary regeneration efficiency; and can effectively utilize the extra NO2 generated by methanol combustion and convert it into a DPF regeneration advantage.

[0063] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine, characterized in that: It includes the following steps: S1: Initialize the input conditions; S2: Set the auxiliary regeneration threshold, obtain the input value, compare the input value with the DPF carbon loading reading M, and obtain the first comparison result; S3: Set the DPF passive regeneration minimum effective temperature threshold T0, compare T0 with T, and obtain the second comparison result; S4: Make a comprehensive determination of the first comparison result and the second comparison result to generate a DPF regeneration status instruction; S5: Execute the DPF regeneration status instruction.

2. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 1, characterized in that: The step S1 includes: S11: Obtain the DPF carbon loading reading M of the engine controller in real time; S12: Collect the actual temperature T of the DPF through a temperature sensor.

3. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 2, characterized in that: The step S2 includes: S21: Set the carbon loading threshold M1 for the auxiliary regeneration mode and the driving regeneration trigger threshold M2, where M1 < M2; S22: Receive the input of the M1 and M2 parameters and synchronize them to the program; S23: Receive the input of the M parameter, compare M1, M2, and M, and confirm the first comparison result.

4. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 3, characterized in that: The step S23 includes: S231: When both conditions are met: M1 < M < M2, confirm that the first comparison result is that the carbon loading is compliant; S232: When either condition of M1 < M < M2 is not met, confirm that the first comparison result is that the carbon loading is non-compliant.

5. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 4, characterized in that: The step S3 includes: S31: Receive the input of the T0 parameter; S32: Compare T with T0; S33: Obtain the second comparison result.

6. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 5, characterized in that: The step S33 includes: S331: If T > T0 is satisfied, the second comparison result is that the temperature is compliant; S332: If T < T0, the second comparison result is that the temperature is non-compliant.

7. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 6, characterized in that: The step S4 includes: S41: If the first comparison result is that the carbon loading is compliant and the second comparison result is that the temperature is compliant, the DPF regeneration status instruction is to trigger passive regeneration; S42: If the conditions corresponding to S41 are not met, set the DPF regeneration status instruction to maintain the original control strategy.

8. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 7, characterized in that: The step S5 includes: S51: If the DPF regeneration status instruction is to trigger passive regeneration, the engine enters the auxiliary regeneration mode; S52: If the DPF regeneration status instruction is to maintain the original control strategy, skip this step.

9. A control strategy for extending the DPF regeneration period of a methanol-diesel dual-fuel engine as claimed in claim 8, characterized in that: In the step S51, the steps executed in the auxiliary regeneration mode include: S511: In the engine R & D stage, based on the DPF accumulated carbon amount and the DPF temperature as input conditions, set a correction plan; S512: According to the correction plan, calculate the real-time air-fuel ratio through the intake air flow and the fuel flow, and correct the ratio of methanol and diesel according to the air-fuel ratio to obtain the methanol injection correction coefficient; S513: According to the correction plan, increase the proportion of methanol combustion until it meets the methanol injection correction coefficient.

Images