Non-road national fourth diesel engine aftertreatment system and intelligent regeneration method

Abstract

The application discloses a kind of non-road fourth diesel engine post-processing system intelligent regeneration method, comprising the following steps: S1, through differential pressure sensor, temperature sensor and engine operating parameter, using multi-source carbon load fusion algorithm Real-time calculation G-CDPF carbon load;S2, when carbon load exceeds dynamic threshold or environmental condition meets plateau low temperature compensation condition, start burner regeneration mode;S3, in the regeneration process, real-time monitoring G-CDPF outlet temperature T_out, if it exceeds 650 DEG C then trigger safety protection strategy.The application has fusion multi-source carbon load fusion algorithm (differential pressure+temperature+carbon load model) and plateau low temperature adaptive module, realizes the advantages such as dynamic optimization of regeneration strategy.

Description

Technical Field

[0001] This invention relates to the field of engine aftertreatment technology, and in particular to an aftertreatment system and intelligent regeneration method for a non-road China IV diesel engine. Background Technology

[0002] Currently, non-road Euro IV diesel engines generally adopt the DOC+DPF+SCR route. Extensive field testing and failure analysis have revealed structural defects in this route:

[0003] (1) Rigid dependence on precious metals: DOC requires 15~25g / ft³ of precious metals (Pt / Pd) to maintain an oxidation window above 250℃. According to industry data, DOC accounts for 65%~75% of the total precious metals in post-treatment, increasing the cost per unit by 3000~5000 yuan, and is significantly affected by international price fluctuations (Pt price fluctuated by ±22% in 2023).

[0004] (2) Functional coupling vulnerability: The oxidation of NO by DOC to form NO2 is a prerequisite for the passive regeneration of DPF. However, under high altitude (>3000m) or low temperature (<-15℃) conditions, the exhaust temperature is often below 220℃, and the DOC oxidation efficiency drops sharply to <30%, resulting in the loss of the passive regeneration capability of DPF. This forces the DPF to trigger active regeneration at high frequency, which aggravates the load on the starter / battery (directly related to the starting failure at 5200m / -16℃ mentioned by the user).

[0005] (3) Irreversible poisoning: When the sulfur content of fuel is >10ppm, the front end of DOC is rapidly sulfided (SO2→sulfate), which blocks the pores and is difficult to recover through conventional regeneration (the regeneration temperature needs to be >650℃, but the tolerance limit of DOC carrier is 600℃), resulting in continuous exceedance of CO / HC emissions;

[0006] (4) System redundancy and space conflict: The functions of DOC and DPF partially overlap (both contain oxidation catalyst layers), and the volume of DOC accounts for 30%~40% of the total length of the post-treatment, making it difficult to lay out on space-constrained models such as small excavators.

[0007] Existing improvement attempts and reasons for their failure

[0008] (1) Scheme A (burner + non-catalytic DPF): DOC and CDPF precious metals are omitted, but the CO / HC conversion rate is <40% (at 250℃) during the cold start stage, which cannot meet the National IV limit (the measured CO reaches 6.8g / kWh).

[0009] (2) Scheme B (low precious metal DOC+DPF): The precious metal DOC is reduced to 10g / ft³, but the NO oxidation efficiency is insufficient under high-altitude conditions, the DPF regeneration interval is shortened by 50%, and the fuel economy deteriorates.

[0010] (3) Option C (electric heating DOC): Add an electric heating module to assist in low-temperature oxidation, but the power consumption is high (≥2kW), the cost increases, and the unstable voltage at high altitudes leads to poor reliability.

[0011] This invention adopts a "multi-source sensing-dynamic fusion-environmental adaptation" regeneration decision architecture: it integrates physical sensor signals with a virtual carbon load model, and through dynamic weight adjustment of environmental factors, it achieves accurate triggering and duration optimization of the regeneration strategy, solving the problem of misjudgment of traditional single differential pressure signals under high-altitude / low-temperature conditions.

[0012] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0013] The main objective of this invention is to propose a post-processing system with a dynamic optimization of regeneration strategy by integrating a multi-source carbon loading fusion algorithm (pressure difference + temperature + carbon loading model) with a high-altitude low-temperature adaptive module.

[0014] Therefore, this invention proposes an after-treatment system and intelligent regeneration method for non-road China IV diesel engines.

[0015] Preferably, the present invention may also have the following technical features:

[0016] A method for intelligent regeneration of a non-road China IV diesel engine aftertreatment system includes the following steps:

[0017] S1. The carbon load of G-CDPF is calculated in real time using a multi-source carbon load fusion algorithm based on differential pressure sensor, temperature sensor and engine operating parameters.

[0018] S2. When the carbon load exceeds the dynamic threshold or the environmental conditions meet the plateau low temperature compensation conditions, the burner regeneration mode is activated.

[0019] S3. During the regeneration process, the outlet temperature T_out of G-CDPF is monitored in real time. If it exceeds 650℃, a safety protection strategy is triggered.

[0020] Further, in step S1, in the multi-source carbon loading fusion algorithm, carbon loading = α·f (ΔP) + β·f(T_out-T_in) + γ·f (carbon loading model), where α, β, and γ are weighting coefficients, ΔP is the G-CDPF pressure difference, T_out is the G-CDPF outlet temperature, and T_in is the G-CDPF inlet temperature.

[0021] Furthermore, the weighting coefficients α, β, and γ are dynamically adjusted based on altitude and ambient temperature.

[0022] Furthermore, among them,

[0023] α = 0.4 + 0.001×Altitude - 0.005×|T_env|

[0024] β = 0.3 - 0.0008×Altitude + 0.004×|T_env|

[0025] γ = 0.3 - 0.0002×Altitude + 0.001×|T_env|

[0026] Altitude: altitude (m), T_env: ambient temperature (°C).

[0027] Furthermore, in step S2, when the altitude is >3000m, the regeneration trigger threshold is reduced: Threshold_new = Threshold_base × (1 - 0.00005×Altitude);

[0028] Furthermore, in step S2, when T_env < -15℃, the burner preheating time is extended: t_new = t_base × (1 + 0.015 × |T_env|).

[0029] Furthermore, in step S3, the installation protection strategy refers to reducing the amount of oil supplied to the burner or suspending burner ignition.

[0030] A non-road China IV diesel engine aftertreatment system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the aforementioned intelligent regeneration method for the diesel engine aftertreatment system.

[0031] The beneficial effects of this invention compared to existing technologies include: It is the first to propose a "burner + G-CDPF" DOC-free architecture, breaking the industry's path dependence on DOC. The axial gradient coating of G-CDPF achieves "functional zoning and precise delivery of precious metals," resolving the contradiction between low load and high activity. The multi-source carbon load fusion algorithm combined with a high-altitude adaptive module overcomes the industry challenge of regeneration reliability under extreme operating conditions. This invention's technical solution is not only applicable to non-road China IV emission standards but can also be extended to China V emission standards, marine engines, and generator sets, possessing broad industrialization prospects.

[0032] By integrating a multi-source carbon loading fusion algorithm (pressure difference + temperature + carbon loading model) with a high-altitude low-temperature adaptive module, dynamic optimization of the regeneration strategy is achieved. Test bench and high-altitude measurements at 5200 meters / -25℃ show that CO / HC emissions are consistently better than the National IV emission limit by 30%, PM capture efficiency is ≥95%, regeneration power is 100%, and system cost is reduced by 28.5%. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the post-processing system layout of the present invention.

[0034] Figure 2 This is the control flowchart of the present invention.

[0035] Figure 3 This is a flowchart of the coating method of the present invention.

[0036] Figure 4 This is a flowchart of the carrier pretreatment process of the present invention.

[0037] Figure 5 This is a flow chart of the carrier inlet section coating process of the present invention.

[0038] Figure 6 This is a flow chart of the coating process for the main filter section of the carrier in this invention. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope or application of the present invention.

[0040] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0041] like Figures 1-2 The method for intelligent regeneration of a non-road China IV diesel engine aftertreatment system is shown. In some examples, the aftertreatment system is a DOC-free gradient catalytic DPF (G-CDPF). The regeneration method includes the following steps:

[0042] S1. The carbon load of G-CDPF is calculated in real time using a multi-source carbon load fusion algorithm based on differential pressure sensor, temperature sensor and engine operating parameters.

[0043] In step S1, the multi-source carbon loading fusion algorithm is defined as carbon loading = α·f (ΔP) + β·f (T_out-T_in) + γ·f (carbon loading model), where the weighting coefficients α, β, and γ are dynamically adjusted according to altitude and ambient temperature, ΔP is the G-CDPF pressure difference, T_out is the G-CDPF outlet temperature, and T_in is the G-CDPF inlet temperature.

[0044] Where α = 0.4 + 0.001×Altitude - 0.005×|T_env| (high altitude / low temperature compensation)

[0045] β = 0.3 - 0.0008×Altitude + 0.004×|T_env|

[0046] γ = 0.3 - 0.0002×Altitude + 0.001×|T_env|

[0047] Altitude: altitude (m), T_env: ambient temperature (°C).

[0048] By integrating a multi-source carbon loading fusion algorithm (pressure difference + temperature + carbon loading model) with a high-altitude low-temperature adaptive module, dynamic optimization of the regeneration strategy is achieved. Test bench measurements at 5200 meters / -25℃ high altitude show that CO / HC emissions are consistently better than the National IV emission limits by 30%, PM capture efficiency is ≥95%, regeneration power is 100%, and system cost is reduced by 28.5%. (See Table 1.)

[0049]

[0050] Compared with traditional differential pressure control strategies, the multi-source carbon loading fusion algorithm of this invention has the following advantages, as shown in Table 2.

[0051]

[0052] Low-temperature reliability refers to the ability to regenerate in low-temperature environments.

[0053] S2. When the carbon load exceeds the dynamic threshold or the environmental conditions meet the plateau low temperature compensation conditions, the burner regeneration mode is activated.

[0054] In step S2, when the altitude is >3000m, the regeneration trigger threshold is reduced: Threshold_new = Threshold_base × (1 - 0.00005×Altitude);

[0055] When T_env < -15℃, the burner preheating time is extended: t_new = t_base × (1 + 0.015 × |T_env|).

[0056] In other words, when the altitude is greater than 3000 meters or the ambient temperature is less than -15℃, the regeneration trigger threshold is reduced by 15% to 25%, and the burner preheating time is extended by 40% to 60%.

[0057] S3. During the regeneration process, the outlet temperature T_out of G-CDPF is monitored in real time. If it exceeds 650℃, a safety protection strategy is triggered.

[0058] In step S3, the installation protection strategy refers to reducing the amount of oil supplied to the burner or suspending burner ignition.

[0059] The burner is configured with dual operating modes, including an oxidation-assisted mode and a regeneration mode;

[0060] If the ambient temperature T_env < 0℃ and the engine is running, the oxidation-assisted mode is activated. The oxidation-assisted mode is used to raise the G-CDPF inlet temperature to the first preset temperature to activate the catalytic oxidation function of the after-processor.

[0061] If the carbon load model determines that the post-treatment needs to be regenerated, the burner will start the regeneration mode.

[0062] Preferably, the first preset temperature is 280-300℃. Traditional DOC+DPF solutions that include DOC rely on DOC producing NO2 (passive heating) + fuel injection (active heating) to raise the exhaust temperature, thereby burning particles inside the DPF. In this embodiment, the aftertreatment inlet temperature is raised to the first preset temperature through active energy supply from burner combustion. This raises the exhaust temperature without DOC oxidation, compensating for the lack of a low-temperature oxidation window caused by the absence of DOC, and completely eliminating the dependence on DOC oxidation to produce NO2 and thus raise the temperature.

[0063] In oxidation-assisted mode: the fuel injection flow rate delivered to the burner is 0.7-1 L / h, preferably 0.8 L / h. After burner ignition, it operates continuously for 60-90 seconds, preferably 60 seconds, to ensure that the G-CDPF intake temperature (inlet temperature) T_in ≥ the first preset temperature. Preferably, after activating oxidation-assisted mode, once the engine has successfully started and entered idle condition, the idle speed is increased by 50 rpm via the engine ECU and maintained for a time t1 before fuel injection flow is delivered to the burner and ignition is initiated. Preferably, the continuous operating time t1 is 8-11 seconds. Before burner ignition, the exhaust flow rate is increased by raising the idle speed to ensure oxygen supply to the burner and avoid incomplete combustion. During burner ignition, the main injection timing is delayed by 3°CA to reduce exhaust temperature fluctuations caused by delayed combustion.

[0064] Preferably, the relationship between the burner fuel injection quantity Q and the ambient temperature T_env is as follows:

[0065]

[0066] If the G-CDPF intake temperature T_in ≥ the first preset temperature, or the burner continuous operating time t2 ≥ the first preset time, then the oxidation-assisted mode is exited. Preferably, the first preset time is 90s. After exiting the oxidation-assisted mode, the main injection timing is delayed by 3°CA for 12-18s before resuming normal calibration to ensure that the G-CDPF is fully preheated.

[0067] In oxidation-assisted mode, CO and THC emissions were significantly improved, as detailed in Table 3.

[0068]

[0069] The advantages of the burner-assisted oxidation mode of the present invention compared with traditional fuel post-injection regeneration and electrically heated DOC temperature rise oxidation are shown in Table 4:

[0070]

[0071] Optionally, in one embodiment of the gradient catalytic DPF (G-CDPF), the surface of the G-CDPF support is coated with an axial noble metal gradient. The axial direction of the support is divided into two regions: an inlet section and a main filtration section, which are respectively coated with highly active catalyst slurry A and slurry B. Preferably, the inlet section is the 0-30% length region of the support, and the main filtration section is the 30-100% length region of the support.

[0072] The slurry A, by mass fraction, comprises 78.5% alumina carrier (γ-Al₂O₃), 5.00% platinum (Pt), palladium (Pb), 5.00% cerium-zirconium solid solution (CeO₂-ZrO₂), 1.50% lanthanum oxide modifier (La₂O₃), 7.50% binder (silica sol), 2.50% nitric acid, and 2.50% deionized water, with platinum (Pt) and palladium (Pb) accounting for 2.5% by mass. The mass ratio of Pt to Pd in ​​slurry A is (3:1) to (5:1), meaning Pt is 3 to 5 times the amount of Pd. For example, in slurry A, the mass fractions of Pt and Pd are 2% and 0.5%, respectively, or 1.92% and 0.58%, or 2.08% and 0.42%.

[0073] The preparation process of slurry A includes: 1) grinding the raw materials in a ball mill according to their composition; 2) ball milling for 4 hours to control the fineness of the slurry D90 ≤ 5 μm, thus producing slurry A. D90 indicates that 90% of the particles have a diameter ≤ 5 μm.

[0074] The slurry B, by mass fraction, comprises 81.0% alumina carrier (γ-Al2O3), platinum (Pt), palladium (Pb), 3% manganese oxide combustion improver (MnOx), 1.20% zirconium oxide stabilizer (ZrO2), 1.00% barium oxide oxygen storage material (BaO), 8.00% binder (aluminum sol), 2.00% nitric acid, and 2.55% deionized water, with platinum (Pt) and palladium (Pb) accounting for 1.25% together. The mass ratio of Pt to Pd in ​​slurry B is (1.5:1) to (2.5:1), with Pt being 1.5 to 2.5 times that of Pd. For example, in slurry B, the mass fractions of Pt and Pd are 0.83% and 0.42%, or 0.75% and 0.50%, or 0.89% and 0.36%, respectively.

[0075] The preparation process of slurry B includes: 1) Grinding the raw materials in a ball mill according to their composition; ball milling for 3 hours, controlling the fineness of the slurry D90≤8μm, thus producing slurry B. D90 indicates that 90% of the particles have a diameter ≤8μm.

[0076] like Figure 3-6 The axial gradient coating method for a non-road China IV diesel engine aftertreatment system, as shown, includes the following steps:

[0077] S1. Carrier pretreatment:

[0078] S101. Select cordierite honeycomb ceramic carrier and calcine the carrier at 550℃ for 1.5-3 hours to remove impurities; after calcination, remove and let it stand to cool.

[0079] In step S101, the carrier porosity is 50±2%. Preferably, the carrier is calcined for 2 hours.

[0080] S102. After cooling to room temperature, use compressed air to blow through the channels of the carrier to remove any debris adhering to the channels and ensure that the channels are not blocked.

[0081] S103. Immerse the carrier in a 10% nitric acid solution for 30 minutes to increase the surface hydroxyl content and improve coating adhesion.

[0082] S104. Wash the carrier three times with deionized water, then dry it at 110℃ for 2 hours, and then let it cool naturally.

[0083] S2, Inlet Section Coating Process:

[0084] S201. Place the carrier vertically and seal the bottom of the carrier. Inject slurry A to 30% of the height of the carrier. For example, if the length of the carrier is 300mm, inject slurry A to 90mm of the height of the carrier, and then immerse for 30 seconds.

[0085] Preferably, a vacuum pump is connected to the top of the carrier and started to draw air out of the carrier. The suction pressure is 0.08 MPa and the time is 15 seconds, which helps the slurry to be evenly distributed on the carrier wall.

[0086] S202. Then place the carrier in a drying device and dry it at 110°C for 3 hours to allow the moisture to evaporate slowly and prevent the coating from cracking.

[0087] S203, then raise the drying temperature to 550℃ and keep it at that temperature for 2 hours to ensure that the active components of the catalyst adhere firmly;

[0088] In step S203, the heating rate from 110℃ to 550℃ is 2℃ / min.

[0089] S204. Remove the carrier from the drying device and cool it to room temperature. Then use compressed air to remove the floating powder / debris from the surface of the carrier.

[0090] S3. Main filter section coating process:

[0091] S301. Place the carrier with the inlet section coating completed vertically, seal the inlet section to prevent slurry B from flowing into the inlet section, and slowly inject slurry B until it fills the main filter section pores; for example, if the length of the carrier is 300mm, inject slurry A into the carrier at position 0-90mm, and inject slurry B into the carrier at position 90-300mm.

[0092] S302. The process of immersion-spin-drying is adopted: after immersion for 40 seconds, centrifugate at 800 r / min for 10 seconds;

[0093] S303. Place the carrier in a drying device and dry it at 110°C for 4 hours, then gradually raise the temperature to 500°C and keep it at that temperature for 3 hours.

[0094] In step S303, the heating rate from 110℃ to 550℃ is 3℃ / min.

[0095] S304, the entire carrier is calcined again at 550℃ for 1 hour to enhance the bonding strength of the coating interface;

[0096] S305. Remove the carrier and let it cool down to complete the carrier coating.

[0097] In the above technical solution, the selected G-CDPF carrier specification is Φ280×300mm, with a total precious metal loading of 3.8 g / ft³. This compares to the traditional DOC+DPF solution, where the DOC specification is Φ250×200mm and the precious metal loading is 20 g / ft³ (Pt:Pd=2:1). The traditional DOC+DPF solution uses significantly more precious metals than the total precious metal loading of 3.8 g / ft³ in this invention.

[0098] When the burner is in regeneration mode, the fuel injection flow rate supplied to the burner is 1.3-1.8 L / h, preferably 1.5 L / h. The burner operates continuously for 12-18 min, preferably 15 min, and the PID-controlled G-CDPF outlet temperature is 580±20℃.

[0099] In the above, if the decrease rate of the G-CDPF pressure difference ΔP is < 5% / min, then the regeneration time should be extended.

[0100] If the G-CDPF outlet temperature T_out > 650℃, then reduce the oil supply to the burner / suspend burner ignition (safety protection strategy).

[0101] The comparison between the proposed solution and the traditional DOC+DPF solution is shown in Table 5:

[0102]

[0103] A non-road China IV diesel engine aftertreatment system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the aforementioned intelligent regeneration method for the diesel engine aftertreatment system.

[0104] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0105] Although exemplary embodiments of the invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the invention without departing from the central concepts of the invention described herein. Therefore, the invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the invention.

Claims

1. A method for intelligent regeneration of a non-road Euro IV diesel engine aftertreatment system, characterized in that: Includes the following steps: S1. The carbon load of G-CDPF is calculated in real time using a multi-source carbon load fusion algorithm based on differential pressure sensor, temperature sensor and engine operating parameters. S2. When the carbon load exceeds the dynamic threshold or the environmental conditions meet the plateau low temperature compensation conditions, the burner regeneration mode is activated. S3. During the regeneration process, the outlet temperature T_out of G-CDPF is monitored in real time. If it exceeds 650℃, a safety protection strategy is triggered.

2. The intelligent regeneration method for the aftertreatment system of a non-road Euro IV diesel engine as described in claim 1, characterized in that: In step S1, the multi-source carbon loading fusion algorithm is defined as: carbon loading = α·f (ΔP) + β·f (T_out-T_in) + γ·f (carbon loading model), where α, β, and γ are weighting coefficients, ΔP is the G-CDPF pressure difference, T_out is the G-CDPF outlet temperature, and T_in is the G-CDPF inlet temperature.

3. The intelligent regeneration method for the aftertreatment system of a non-road National IV diesel engine as described in claim 2, characterized in that: The weighting coefficients α, β, and γ are dynamically adjusted based on altitude and ambient temperature.

4. The intelligent regeneration method for the aftertreatment system of a non-road National IV diesel engine as described in claim 3, characterized in that: in, α = 0.4 + 0.001×Altitude - 0.005×|T_env| β = 0.3 - 0.0008×Altitude + 0.004×|T_env| γ = 0.3 - 0.0002×Altitude + 0.001×|T_env| Altitude: altitude (m), T_env: ambient temperature (°C).

5. The intelligent regeneration method for the aftertreatment system of a non-road Euro IV diesel engine as described in claim 1, characterized in that: In step S2, when the altitude is >3000m, the regeneration trigger threshold is reduced: Threshold_new = Threshold_base × (1 -0.00005×Altitude).

6. The intelligent regeneration method for the aftertreatment system of a non-road Euro IV diesel engine as described in claim 1, characterized in that: In step S2, when T_env < -15℃, the burner preheating time is extended: t_new = t_base × (1 + 0.015 × |T_env|).

7. The intelligent regeneration method for non-road National IV diesel engine aftertreatment system as described in claim 1, characterized in that: In step S3, the installation protection strategy refers to reducing the amount of oil supplied to the burner or suspending burner ignition.

8. A non-road Euro IV diesel engine aftertreatment system, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, it implements the intelligent regeneration method for a diesel engine aftertreatment system as described in any one of claims 1-7.

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