Diesel engine system for non-road mobile machine and DPF regeneration control method

Abstract

The invention discloses a diesel engine system for a non-road mobile machine and a DPF regeneration control method. The system includes an engine body, an aftertreatment system, and an electronic control unit. The engine body comprises a crank connecting rod mechanism, a fuel oil system and a turbocharging system. The aftertreatment system comprises a diesel oxidation catalyst and a diesel particulate filter, and is provided with a DPF differential pressure sensor and an exhaust temperature sensor. The system is characterized by further comprising a variable compression ratio executing mechanism integrated in the crank connecting rod mechanism. The ECU is configured to control the variable compression ratio executing mechanism to reduce the compression ratio of the engine and cooperatively adjust the oil injection timing when it is judged that DPF active regeneration needs to be started, so that the exhaust temperature is increased to the range needed by DPF regeneration, dependence of a traditional regeneration strategy on post-injection fuel oil is greatly reduced, and fuel oil consumption in the regeneration process is remarkably reduced. The industrial problem that the fuel economy is worsened in the DPF regeneration period is fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of exhaust aftertreatment technology for internal combustion engines, specifically to a diesel engine assembly system for non-road mobile machinery that meets China IV and above emission standards. More particularly, it relates to a diesel engine system for non-road mobile machinery and a DPF regeneration control method. Background Technology

[0002] To meet the stringent emission standards of China IV and above, modern diesel engines for non-road mobile machinery generally employ an aftertreatment system combining a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF). The DPF needs to periodically oxidize and remove captured carbon particles through an "active regeneration" process. Current mainstream technologies mainly rely on the engine electronic control unit (ECU) to control "remote after-injection" fuel, intentionally raising the exhaust temperature to the carbon ignition point (typically >550℃) through in-cylinder afterburning.

[0003] However, this "thermal management" strategy based on additional fuel injection leads to significant fuel penalty, severely deteriorating the engine's operating economy during regeneration. For off-road machinery such as tractors and harvesters that require long-term continuous operation, the high fuel costs resulting from frequent DPF regeneration have become a prominent operational pain point. On the other hand, although modern diesel engine electronic control systems are highly integrated and can precisely control processes such as fuel injection, boosting, and aftertreatment, they still lack active control over the engine's geometric compression ratio, a fundamental structural parameter that determines thermal efficiency. A fixed compression ratio limits the engine's efficiency optimization potential under varying operating conditions and means that, during DPF regeneration, there are few other effective ways to increase exhaust temperature and reduce fuel consumption besides increasing post-injection fuel.

[0004] Therefore, how to efficiently and reliably increase the exhaust temperature required for DPF regeneration without relying on or significantly reducing post-injection fuel, i.e., developing a DPF regeneration collaborative control technology that can be deeply integrated with the engine electronic control network and has fuel consumption advantages, has become a key problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the poor fuel economy of existing DPF regeneration technologies for off-road diesel engines and to provide an innovative diesel engine system for off-road mobile machinery and its DPF regeneration control method. This system introduces a variable compression ratio (VCR) mechanism and intelligently couples it with the engine electronic control unit (ECU) during the active DPF regeneration phase. This achieves efficient increases in exhaust temperature with little or no increase in post-injection fuel, thereby significantly reducing fuel consumption during the DPF regeneration process.

[0006] To achieve the above objectives, the technical solution of the present invention is to design a diesel engine system for non-road mobile machinery, including an engine body, an aftertreatment system, and an electronic control unit (ECU). The engine body includes a crankshaft-connecting rod mechanism consisting of a piston, connecting rod, and crankshaft, a high-pressure common rail fuel system, and a turbocharging system. The aftertreatment system includes a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF), and is equipped with a DPF differential pressure sensor for monitoring the DPF status and at least one exhaust temperature sensor. The system also includes a variable compression ratio actuator integrated into the crankshaft-connecting rod mechanism. The ECU is configured to: when it is determined that active DPF regeneration needs to be initiated, control the variable compression ratio actuator to reduce the engine compression ratio and coordinately adjust the fuel injection timing, thereby increasing the exhaust temperature to the range required for DPF regeneration.

[0007] The high-pressure common rail fuel system includes a high-pressure fuel pump, a common rail, a high-pressure fuel line, and fuel injectors; the turbocharging system includes a turbocharger assembly connected to the intake manifold and the exhaust manifold; and the rear end of the crankshaft is connected to a flywheel.

[0008] The variable compression ratio actuator is a mechanical stepless adjustment mechanism that includes a multi-link, an eccentric control shaft, and a servo motor.

[0009] The ECU is configured to: during active DPF regeneration, use the signal fed back by the exhaust temperature sensor as the closed-loop control target, dynamically adjust the combination of compression ratio and injection timing, and coordinate the operation of the turbocharger system to keep the exhaust temperature stably maintained within the preset DPF regeneration temperature window.

[0010] During the active regeneration of the DPF, the ECU controls the compression ratio to drop to a range of 14:1 to 16:1 and reduces or eliminates the amount of in-cylinder post-injection fuel used to increase exhaust temperature.

[0011] The diesel engine system for off-road mobile machinery also includes a lubrication system and a cooling system; the ECU also intervenes in the start / stop or speed of the fan based on the coolant temperature during DPF regeneration.

[0012] During DPF regeneration, the ECU restricts fan operation based on coolant temperature to minimize heat dissipation. When the coolant temperature is below 95°C, the ECU prevents the fan from starting.

[0013] A DPF regenerative control method for a diesel engine system used in off-road mobile machinery includes the following steps: Monitor DPF carbon loading; when the regeneration trigger threshold is reached, enter the co-regeneration mode. Control the variable compression ratio actuator to reduce the engine compression ratio; The fuel injection timing should be advanced accordingly; Based on feedback from the exhaust temperature sensor, the compression ratio and injection timing are adjusted in a closed loop to maintain the target exhaust temperature; After DPF regeneration is complete, the compression ratio and injection timing are restored to normal values.

[0014] The advantages and beneficial effects of this invention are as follows: Innovation through system-wide collaboration: This invention does not merely improve a single component, but creatively introduces the "active mechanical adjustment" dimension of the variable compression ratio actuator into a complex system consisting of fuel, intake, exhaust, aftertreatment, and control, achieving global optimization across subsystems.

[0015] Significant energy-saving effect: Through the above synergy, the heat required for DPF regeneration mainly comes from the active optimization of combustion efficiency rather than additional fuel injection. Actual measurements show that the average fuel consumption rate during the regeneration process can be reduced by 25%-35%.

[0016] Seamless Integration with Existing Industries: This invention can be directly upgraded based on existing China IV / China V non-road diesel engine platforms (such as the applicant's CQFWBMCM series). Its mechanical assembly layout, sensor network (including crankshaft speed sensor, camshaft phase sensor, intake air pressure and temperature sensor, coolant temperature sensor, and DPF differential pressure and temperature sensor for the aftertreatment system), and actuator system (including injectors, high-pressure fuel pump solenoid valves, turbocharger assembly exhaust bypass valve, EGR valve, fan relay, etc.) all fully utilize existing standard configurations. Industrialization only requires integrating a variable compression ratio (VCR) actuator and strategically upgrading the ECU software; no large-scale modifications to the basic hardware architecture are required. Therefore, it exhibits good technology inheritance, low industrialization resistance, and low upgrade costs.

[0017] Improved reliability: Reduced reliance on after-injection lowers the risk of oil dilution caused by it. Simultaneously, precise closed-loop exhaust temperature control protects DPF and DOC, extending the lifespan of the aftertreatment system. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the external characteristic curve of a diesel engine system for non-road mobile machinery according to a first embodiment of the present invention; Figure 2 yes Figure 1 A perspective view of the corresponding diesel engine system used in off-road mobile machinery; Figure 3 yes Figure 2 The main view; Figure 4 yes Figure 3 Top view; Figure 5 yes Figure 3 The right view; Figure 6 yes Figure 3 The left view; Figure 7 yes Figure 3 Rear view; Figure 8 yes Figure 5 Sectional view along axis AA; Figure 9 This is a schematic diagram of a crank-connecting rod mechanism integrating the variable compression ratio actuator described in this invention; Figure 10 This is a schematic diagram of the exhaust manifold in Embodiment 2 of the present invention; Figure 11 yes Figure 10 DD section view.

[0019] In the diagram: 1. Cylinder block; 2. Oil pan; 3. Exhaust manifold; 4. Cylinder head cover; 5. High-pressure fuel line; 6. Generator assembly; 7. Starter assembly; 8. Intake manifold; 9. Aftertreatment assembly; 10. ECU; 11. Crankshaft pulley; 12. Gear chamber cover; 13. Common rail; 14. Air compressor; 15. Water pump assembly; 16. Diesel filter (coarse filter); 17. Diesel filter (fine filter); 18. Oil filter; 19. Turbocharger assembly; 20. Flywheel housing; 21. Flywheel; 22. Fan; 23. Piston; 24. Connecting rod; 25. Crankshaft; 26. Upper connecting rod; 27. Lower connecting rod; 28. Control connecting rod; 29. ​​Eccentric control shaft; 30. Worm gear reducer; 31. Groove; 32. Reinforcing rib. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0021] This invention relates to a diesel engine system for non-road mobile machinery, comprising: 1. Engine mechanical assembly: Engine body and core moving parts: including the engine body; the engine body includes a cylinder block, an oil pan mounted at the bottom of the cylinder block, and a crankshaft and connecting rod mechanism disposed within the cylinder block, the crankshaft and connecting rod mechanism including a piston, a connecting rod, and a crankshaft; the piston is connected to the crankshaft via the connecting rod to convert the reciprocating motion of the piston into the rotational motion of the crankshaft. The front end of the crankshaft drives the water pump assembly, the generator assembly, and the fan via a crankshaft pulley, and the rear end is connected to a flywheel. A crankshaft pulley is fixedly connected to the front end of the crankshaft, and the crankshaft pulley drives the water pump assembly and the generator assembly via a belt drive mechanism (the crankshaft pulley drives the water pump pulley and the generator pulley to rotate simultaneously via a multi-ribbed belt / V-belt, thereby driving the water pump assembly and the generator assembly to work); the fan is mounted on the same shaft as the water pump pulley; the flywheel is fixedly connected to the rear end of the crankshaft.

[0022] High-Pressure Common Rail Fuel System: This system consists of a low-pressure fuel supply subsystem and a high-pressure common rail injection subsystem. Low-Pressure Fuel Supply Subsystem: This includes a fuel tank, a fuel pump, a diesel fuel filter, and low-pressure fuel lines connecting them. It supplies clean fuel to the high-pressure fuel pump (there are two diesel fuel filters: a coarse filter and a fine filter; fuel is pumped from the fuel tank via the fuel pump, flows sequentially through the coarse and fine filters, and is then delivered to the high-pressure fuel pump). High-Pressure Common Rail Injection Subsystem: This includes a high-pressure fuel pump, a common rail, and multiple injectors. The common rail is fluidly connected to the high-pressure fuel pump and each injector via high-pressure fuel lines. The high-pressure fuel pump builds up high-pressure fuel and delivers it to the common rail. The common rail stores and distributes the high-pressure fuel, providing a stable pressure of fuel to each injector via the high-pressure fuel lines. Each injector injects the high-pressure fuel into its corresponding cylinder. The high-pressure fuel pump is directly driven by the engine's camshaft or gear train and operates synchronously with the engine.

[0023] Intake and supercharging system: includes an air filter, a supercharger assembly, and an intake manifold. The supercharger assembly is driven by engine exhaust and is used to pressurize the flowing air; after the exhaust gas drives the supercharger turbine, fresh air is pressurized and sent into the cylinders. Outside air flows sequentially through the air filter, the compressor of the supercharger assembly, and the intake manifold before being introduced into the cylinders; wherein, the turbine of the supercharger assembly is located downstream of the engine exhaust manifold and is driven by exhaust.

[0024] Exhaust and aftertreatment system: including an exhaust manifold, a diesel oxidation catalyst (DOC), and a diesel particulate filter (DPF) connected in sequence along the exhaust flow direction; the engine exhaust is collected by the exhaust manifold and flows sequentially through the DOC and the DPF; wherein, a temperature sensor and a DPF differential pressure sensor are provided before and after the DPF to monitor its operating status.

[0025] Lubrication and cooling system: including the pressure lubrication circulation system consisting of an oil pump, oil filter, and oil pan, and the forced cooling circulation system consisting of a water pump assembly, radiator, and thermostat. The lubrication system forms a pressure circulation loop. The oil pump pressurizes the oil in the oil pan and delivers it to the oil filter, which then distributes it to various lubrication points of the engine. The cooling system forms a forced liquid circulation loop. The water pump assembly drives the coolant to flow through the engine water jacket and exchange heat with the radiator. The thermostat adjusts the circulation path of the coolant according to the temperature (when the coolant temperature is below a first threshold, the thermostat closes the passage to the radiator, allowing the coolant to circulate within the engine in a small loop; when the coolant temperature reaches or exceeds the first threshold, the thermostat opens the passage to the radiator, allowing the coolant to circulate through the radiator in a large loop). During DPF active regeneration, to reduce heat loss, the electronic control unit (ECU) can intervene in the operation of the fan; simultaneously, the thermostat's autonomous adjustment of the circulation path based on coolant temperature helps to concentrate the heat energy of the engine and exhaust system into the aftertreatment system.

[0026] Valve train: includes a camshaft driven by a crankshaft and a valve mechanism controlled by the camshaft.

[0027] 2. Variable compression ratio actuator: The variable compression ratio actuator is a multi-link mechanism, including an upper link, a lower link, and a control link. The upper end of the upper link is hinged to the engine piston via a piston pin; the lower end of the lower link is connected to the connecting rod journal of the engine crankshaft; one end of the control link is connected to the intermediate hinge point of the upper and lower links. The other end of the control link is hinged to an eccentric control shaft. The eccentric control shaft is a driveable shaft, with its eccentric section serving as the pivot point for the control link. A servo motor drives the eccentric control shaft to rotate via a reduction gear (such as a worm gear). When the eccentric control shaft rotates, the position of its eccentric section undergoes circular motion, thereby causing the control link to change the pivot point position. The variable compression ratio actuator can steplessly adjust the engine's geometric compression ratio. The stepless adjustment principle is as follows: the servo motor drives the eccentric control shaft to rotate to different angles → the position of the hinge fulcrum of the control link changes → the included angle between the upper and lower links changes → the height of the piston's top dead center changes → the volume of the combustion chamber changes → the geometric compression ratio is continuously (steplessly) adjusted.

[0028] 3. Electronic Control Unit (ECU) and Sensor Network: The ECU connects to and receives signals from the crankshaft speed sensor, camshaft phase sensor, intake air pressure and temperature sensor, coolant temperature sensor, throttle position sensor, and the aforementioned DPF differential pressure sensor and exhaust temperature sensor, and controls the injectors, turbocharger wastegate valve (if applicable), EGR valve, and the variable compression ratio actuator. The camshaft phase sensor, located at the end of the camshaft, detects valve timing. The intake air pressure and temperature sensor is mounted on the intake manifold to measure the air pressure and temperature before it enters the cylinder. The coolant temperature sensor is mounted on the engine block coolant passage. The throttle position sensor is located within the electronic throttle pedal assembly. The DPF differential pressure sensor monitors the DPF carbon load. The aftertreatment system also includes an exhaust temperature sensor (for regeneration temperature control) located after the DOC and before the DPF, and optionally, another temperature sensor can be located after the DPF to monitor regeneration completion.

[0029] The core innovation of this invention lies in the fact that the ECU is programmed to execute a DPF regenerative collaborative control strategy that deeply integrates all engine subsystems: Normal high-efficiency operation mode: The ECU controls the fuel system to perform precise injection based on the throttle opening and speed, controls the intake and boosting systems to provide appropriate intake air, and adjusts the variable compression ratio actuator to the optimal economic compression ratio (such as 17.5:1-19:1), so that the engine works in the high-efficiency range. It is especially suitable for non-road mobile machinery operating conditions with large load fluctuations and long-term continuous operation.

[0030] DPF Regeneration Intelligent Coordination Mode: This mode is activated when the ECU determines that the carbon load has reached the regeneration threshold based on the DPF differential pressure sensor signal or model. The specific process is as follows: 1. Command Issuance and System Preparation: The ECU notifies the operator of the start of regeneration via the CAN bus or instrument panel. Simultaneously, to ensure efficient thermal management during the regeneration process, the ECU can pre-control the fan to reduce speed or shut down, and monitor the coolant temperature.

[0031] 2. Compression Ratio and Combustion Synergistic Adjustment: The ECU sends a command to the variable compression ratio actuator to quickly reduce the compression ratio from the economic value to a predetermined regeneration value (e.g., 15:1). Simultaneously, the ECU commands the high-pressure common rail fuel system to advance the injection timing appropriately. The combined effect of reducing the compression ratio and advancing the injection results in earlier and more intense combustion, significantly increasing the in-cylinder combustion temperature.

[0032] 3. Intake and Exhaust System Coordination: To ensure stable and efficient combustion, the ECU coordinates the operation of the turbocharger system. Specifically, the ECU aims to maintain the optimal air-fuel ratio by adjusting the opening of the wastegate valve (or variable geometry turbocharger) to control the boost pressure, thereby maintaining the necessary intake volume to match the current combustion mode. After the high-temperature exhaust gas exits the exhaust manifold, it first flows through the DOC (Discharge Organizer). At this point, unburned hydrocarbons (HC) and carbon monoxide (CO) present in the exhaust gas due to the changed combustion conditions undergo oxidation under the catalytic action of the DOC. This exothermic process causes a secondary significant increase in exhaust temperature. An exhaust temperature sensor located before the DPF monitors this temperature in real time and feeds the signal back to the ECU, forming a closed-loop temperature control system.

[0033] 4. Closed-Loop Temperature Control: The ECU uses the target regeneration temperature before the DPF (e.g., 580℃) as the setpoint and the feedback value from the exhaust temperature sensor located before the DPF as the measured value, forming a closed loop. In this closed loop, compression ratio, injection timing, boost pressure, and EGR rate are used as control variables for coordinated adjustment. The ECU's internal control strategy is as follows: When the measured temperature is lower than the target value, the ECU will prioritize or simultaneously adjust towards reducing the compression ratio and advancing the injection timing to quickly increase the combustion temperature and exhaust energy; at the same time, it can adjust the exhaust bypass valve to fine-tune the boost pressure and may reduce the EGR rate to optimize the combustion process. Conversely, when the temperature approaches or exceeds the target, it will perform reverse fine-tuning. Through this dynamic coordinated adjustment of multiple variables, the exhaust temperature is stably maintained within the preset DPF regeneration window.

[0034] 5. Minimized Post-Injection Fuel: Thanks to the main heating effect generated by the aforementioned mechanical and combustion adjustments, the system's reliance on traditional post-injection fuel is significantly reduced. The ECU only needs to activate a very small amount of post-injection for fine-tuning when necessary.

[0035] 6. Regeneration Completion and System Recovery: During the regeneration process, the ECU continuously monitors the signal from the DPF differential pressure sensor. This sensor calculates the differential pressure (ΔP) by measuring the pressure before and after the DPF, which directly reflects the carbon load of the DPF. When the differential pressure (ΔP) continues to decrease and falls below the preset completion threshold, the ECU determines that the carbon soot has been sufficiently removed, and regeneration is complete. Subsequently, the ECU controls the variable compression ratio actuator to restore the compression ratio to the optimal economic compression ratio before regeneration (e.g., 18:1). Control parameters such as injection timing and boost pressure are also simultaneously restored to their normal mapping values. The fan resumes its automatic temperature control logic, and the entire system exits the regeneration mode and returns to normal, efficient operation.

[0036] Based on the above system, the present invention also provides a DPF regeneration control method, comprising: monitoring the DPF carbon load and triggering regeneration; reducing the engine compression ratio and advancing the injection timing; using exhaust temperature as a closed-loop target to coordinately adjust the compression ratio and injection timing; and restoring parameters after regeneration is completed.

[0037] Example 1: As Figures 1 to 9 As shown (for ease of illustration), Figure 8 (A schematic diagram showing the disassembly of the crank-connecting rod mechanism and other parts) is provided, using a turbocharged intercooled diesel engine with a rated power of 74kW as an example (its external characteristic curve is shown in Figure 1). Figure 1 (As shown), the implementation of the present invention is described in detail.

[0038] Basic Assembly: The engine basic assembly includes a cylinder block 1, an oil pan 2, a cylinder head cover 4, and a crankshaft and connecting rod mechanism consisting of a piston 23, a connecting rod 24, and a crankshaft 25. The fuel system is a high-pressure common rail fuel system, which includes a high-pressure fuel pump, a common rail pipe 13, a high-pressure fuel line 5, and fuel injectors; and is equipped with a diesel fuel filter (coarse filter) 16 and a diesel fuel filter (fine filter) 17.

[0039] The intake and exhaust system includes an intake manifold 8, an exhaust manifold 3, and a turbocharger assembly 19 driven by exhaust gases. The aftertreatment system (i.e., aftertreatment assembly 9) is a DOC+DPF combination, namely a diesel oxidation catalyst and a diesel particulate filter, and is equipped with a DPF differential pressure sensor and DPF pre / rear exhaust temperature sensors.

[0040] Engine accessories include a water pump assembly 15, an alternator assembly 6, an air compressor 14, and a fan 22, all driven by the crankshaft via a crankshaft pulley 11; and a starter assembly 7 for starting the engine, which meshes with a ring gear on the flywheel 21. The engine housing includes a flywheel housing 20 and a gear chamber cover 12. The lubrication system includes an oil filter 18.

[0041] Modification and Integration: In the original crank-connecting rod mechanism (such as...) Figure 8 As shown, the variable compression ratio actuator described in this invention is integrated, such as... Figure 9As shown, the mechanism includes an upper connecting rod 26 hinged to piston 23 via a piston pin, a lower connecting rod 27 hinged to the connecting rod journal of crankshaft 25, and a control connecting rod 28 with one end connected to the hinge point of the upper and lower connecting rods (the lower end of the upper connecting rod is hinged to the upper end of the lower connecting rod; the control connecting rod is hinged to the aforementioned hinge point). The other end of the control connecting rod is hinged to an eccentric control shaft 29, which is driven by a servo motor through a worm gear reducer (a support structure for the eccentric control shaft is provided on the crankcase sidewall. One end of the eccentric control shaft extends out of the crankcase and connects to a worm gear reducer 30, which is driven by a servo motor; the axial direction of the eccentric control shaft is aligned with the axial direction of the flywheel; the control connecting rod is not parallel to the eccentric control shaft, more precisely, the control connecting rod oscillates in a plane perpendicular to the axis of the eccentric control shaft). The servo motor is connected to a newly added control port in the engine control unit (ECU10). The ECU adds a dedicated drive output for controlling the servo motor of the variable compression ratio mechanism.

[0042] Example of a collaborative regeneration process: 1. When non-road mobile machinery (such as harvesters) powered by this engine is operating, the ECU continuously monitors the DPF differential pressure. Regeneration is triggered when the carbon load model value reaches 6.5 g / L. The ECU stores a carbon load model. This model calculates and corrects for the carbon soot mass inside the DPF based on the differential pressure value, combined with exhaust flow rate (estimated from engine speed, intake volume, etc.), exhaust temperature, etc.; when the carbon load model estimate calculated by the ECU based on the DPF differential pressure sensor signal and other parameters reaches 6.5 g / L...

[0043] 2. The ECU displays "Regeneration in progress" on the instrument panel and controls the fan 22 to temporarily delay its start. Subsequently, within 2 seconds, the compression ratio is reduced from 18.2:1 to 15.8:1, while the injection timing is advanced by 2.5° crankshaft angle (injection timing is expressed in crankshaft angle, that is, the injection action occurs at a specific crankshaft angle position before the piston reaches top dead center).

[0044] 3. The engine exhaust tone changes slightly, and the turbocharger maintains boost pressure in response to ECU commands. After approximately 45 seconds, the exhaust temperature sensor located before the DPF shows the temperature rising from 390°C to 565°C.

[0045] 4. The ECU enters the temperature closed-loop maintenance phase, stabilizing the temperature at 575℃±10℃ by fine-tuning the compression ratio (±0.3) and injection timing (±0.5°). During this period, only a very small amount of post-injection is triggered when the temperature occasionally fluctuates to the lower limit.

[0046] 5. After approximately 18 minutes of regeneration, the differential pressure value detected by the DPF differential pressure sensor drops below the threshold, indicating that the carbon load has been removed to below 1 g / L, and the ECU determines that regeneration is complete. The compression ratio and injection timing smoothly return to normal values ​​within 5 seconds.

[0047] 6. According to calculations, this regeneration method saves approximately 31% of fuel compared to the original pure post-injection regeneration strategy.

[0048] Comparison table of DPF regeneration performance between the proposed solution and the traditional post-spray solution: Performance indicators Traditional rear spray solution VCR Collaboration Scheme of the Invention Performance improvement Average fuel consumption increase rate during regeneration +38% (baseline) +10% A decrease of approximately 28 percentage points Regeneration heating time (to 550℃) ~90 seconds ~45 seconds shorten by about 50% Typical regeneration time ~25 minutes ~18 minutes shortened by approximately 28% Post-injection fuel dependence High (primary heat source) Extremely low (with auxiliary fine-tuning) Significantly reduced Oil dilution risk higher Significantly reduced reliability improvement

[0049] Example 2: The difference from Example 1 is that, as shown in Example 2... Figure 10 , Figure 11 As shown, the exhaust manifold 3 includes multiple manifold branches connecting the exhaust ports of each cylinder and a collection section that converges to the turbocharger interface. In a predetermined high-stress area of ​​the manifold branches and / or the collection section, an artificially introduced stress guiding structure is provided. The stress guiding structure is configured to preferentially undergo controllable micro-deformation or micro-cracks under thermal cycling loads compared to other areas, in order to release localized stress concentration.

[0050] The stress-guiding structure consists of continuous or discontinuous micro-grooves 31 formed by laser processing. Several grooves are provided, spaced apart and closely arranged, and the grooves are V-shaped or U-shaped.

[0051] The planned high-stress areas include the outer edge of the manifold junction, the area between flange bolt holes, and the outer wall of the bend.

[0052] Around the area where the stress guiding structure is provided, locally thickened wall thickness or reinforcing ribs 32 are provided.

[0053] In existing technologies, exhaust manifolds: traditional cast manifolds have inconsistent lengths and shapes of exhaust passages for each cylinder, which can easily lead to exhaust interference and uneven utilization of pulse energy, affecting turbo response. The shape of the manifold also directly affects the distribution of thermal stress, making it prone to cracking.

[0054] This embodiment, with its following configuration, will have the following beneficial effects: Reliability Enhancement: By adopting a reverse thinking approach, the generated cracks are utilized to transform the random and destructive crack failure mode into a predictable and safe stress relief mode, greatly extending the service life of the manifold.

[0055] Performance optimization: A more uniform stress distribution allows for a more extreme lightweight design of the manifold (because there is no need to thicken it everywhere to prevent unknown cracks), which may result in a faster turbine response.

[0056] Maintainability: If visible microcracks appear at the preset release point, it can serve as a "health indicator" rather than indicating that the component has failed immediately.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Diesel engine system for off-road mobile machines, characterized in that, The system comprises an engine body, an aftertreatment system and an electronic control unit (ECU), the engine body includes a crank connecting rod mechanism composed of a piston, a connecting rod and a crankshaft, a high-pressure common rail fuel system and a turbocharging system; the aftertreatment system includes a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF), and is provided with a DPF differential pressure sensor for monitoring the state of the DPF and at least one exhaust gas temperature sensor; the system further includes a variable compression ratio actuator integrated in the crank connecting rod mechanism; the ECU is configured to: when it is determined that the DPF active regeneration needs to be started, control the variable compression ratio actuator to reduce the engine compression ratio, and adjust the fuel injection timing in coordination, so as to raise the exhaust gas temperature to the required range for DPF regeneration; The high-pressure common rail fuel system includes a high-pressure fuel pump, a common rail pipe, a high-pressure fuel pipe and an oil injector; the turbocharging system includes a supercharger assembly connected with an intake manifold and an exhaust manifold; the rear end of the crankshaft is connected with a flywheel; The variable compression ratio actuator is a mechanical stepless adjustment mechanism including a plurality of connecting rods, an eccentric control shaft and a servo motor; The ECU is configured to: during the DPF active regeneration, take the signal fed back by the exhaust gas temperature sensor as a closed-loop control target, dynamically adjust the combination of the compression ratio and the fuel injection timing, and coordinate the operation of the turbocharging system, so as to stabilize and maintain the exhaust gas temperature within the preset DPF regeneration temperature window; During the DPF active regeneration, the ECU controls the compression ratio to be reduced to the range of 14:1 to 16:1, and reduces or cancels the amount of post-injection fuel in the cylinder for raising the exhaust gas temperature.

2. The diesel engine system for off-highway mobile machines of claim 1, characterized in that: The diesel engine system for non-road mobile machinery further includes a lubricating system and a cooling system; during the DPF regeneration, the ECU also intervenes in the start-stop or rotation speed of the fan according to the coolant temperature.

3. A DPF regeneration control method for a diesel engine system of a non-road mobile machine according to any one of claims 1-2, characterized in that, The method comprises the following steps: Monitoring the carbon load of the DPF, and entering the coordinated regeneration mode when the regeneration trigger threshold is reached; Controlling the variable compression ratio actuator to reduce the engine compression ratio; Correspondingly advancing the fuel injection timing; Based on the feedback of the exhaust gas temperature sensor, closed-loop adjusting the compression ratio and the fuel injection timing to maintain the target exhaust gas temperature; After the DPF regeneration is completed, restoring the compression ratio and the fuel injection timing to the normal values.

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