An electronically controlled high-pressure controllable injection air-cooled diesel engine

Abstract

The application provides an electric control high-pressure controllable injection air-cooled diesel engine and relates to the technical field of diesel engines. The electric control high-pressure fuel injection system is used to replace the traditional mechanical plunger pump oil supply system, and the electric control high-pressure fuel injection system comprises an electric control unit, an electric control unit pump, an oil supply cam, a low-pressure oil circuit, a high-pressure oil pipe and an oil injector. The electric control unit is electrically connected with the oil injector control valve to realize accurate control of the injection amount, injection time and injection duration. By optimizing the electric control unit pump plunger parameters, the oil supply cam profile, the low-pressure oil circuit oil supply pressure, the high-pressure oil pipe specifications and the oil injector nozzle structure, the peak injection pressure of no less than 1200bar under the rated working condition is realized. The application realizes dynamic self-adaptive adjustment of the full working condition injection parameters, significantly improves the fuel atomization quality and the in-cylinder combustion efficiency, and the minimum fuel consumption rate of the whole machine can be reduced to 221g / kW.h, effectively improving the fuel economy, operation stability and emission performance of the diesel engine.

Description

Technical Field

[0001] This invention belongs to the field of diesel engine technology, and more specifically, relates to an electronically controlled high-pressure controllable injection air-cooled diesel engine. Background Technology

[0002] Air-cooled diesel engines, with their advantages of not requiring a coolant circulation system, compact structure, easy maintenance, and strong environmental adaptability, are widely used in construction machinery, generator sets, and special vehicles, especially in harsh conditions such as water shortage, high temperature, and high dust. Among them, the 12-cylinder V-type turbocharged intercooled air-cooled diesel engine, due to its high output power and high torque reserve, is often used in high-power engineering equipment and mobile power station scenarios. However, with the continuous upgrading of emission regulations for non-road mobile machinery and the increasing market demands for fuel economy, operational stability, and emission performance of diesel engines, the fuel supply system of traditional air-cooled diesel engines has gradually revealed many limitations, becoming a key bottleneck restricting their performance improvement.

[0003] Currently, the vast majority of air-cooled diesel engines still use a mechanical plunger pump fuel supply system. This system achieves fuel pressurization and injection by driving the plunger to reciprocate through a cam. The injection quantity, injection timing, and injection duration are entirely determined by mechanical structural parameters such as the effective stroke of the plunger and the cam profile. It cannot be dynamically adjusted according to operating conditions such as diesel engine speed, load, ambient temperature, and altitude, and has the following significant drawbacks: Low injection pressure and poor atomization: The injection pressure of traditional mechanical plunger pumps is usually difficult to exceed 1000 bar. After the fuel is injected, the droplet size is large and the atomization is uneven. It does not mix well with the air in the cylinder, which easily leads to incomplete combustion. Not only is the fuel consumption rate high, but it also produces a lot of pollutants such as soot and carbon monoxide, making it difficult to meet increasingly stringent emission control requirements.

[0004] Fixed injection parameters and poor adaptability to operating conditions: Mechanical fuel supply systems cannot achieve optimized matching of injection quantity and injection timing across all operating conditions. Under low load conditions, excessive injection and combustion lag are prone to occur, leading to increased fuel consumption and worsened emissions. Under high load conditions, insufficient injection pressure can easily produce locally rich mixtures, causing knocking and carbon deposits, affecting the reliability and service life of diesel engines. At the same time, it is impossible to adjust the injection strategy according to environmental changes such as high altitude and low temperature, which can easily lead to problems such as difficulty in starting, unstable idling, and power loss.

[0005] Poor fuel supply consistency among cylinders and insufficient operational stability: Due to machining errors, component wear, and the inherent characteristics of mechanical pumps, the fuel injection volume of traditional mechanical plunger pumps varies greatly among cylinders. This problem is even more prominent in 12-cylinder V-type high-power air-cooled diesel engines, which can easily lead to large engine vibration and uneven power output. Long-term operation will aggravate the wear of components such as crankshaft connecting rod mechanism and valve train, reducing the reliability of the entire engine.

[0006] Fuel economy and emissions performance are difficult to balance: Traditional fuel supply systems cannot achieve precise control of the combustion process through fuel injection parameter optimization. They can only meet emission requirements by sacrificing power or economy, making it difficult to achieve a synergistic improvement in performance and emissions.

[0007] In existing technologies, some solutions attempt to introduce electronically controlled injection systems into the diesel engine field, such as high-pressure common rail injection systems. However, these systems are complex in structure and expensive, and the high-pressure fuel in the rail is susceptible to cavitation and leakage problems caused by the high temperature of the cylinder block in air-cooled diesel engines. The compatibility and reliability of these systems on air-cooled models are difficult to guarantee. Although some electronically controlled unit pump solutions have achieved basic adjustment of the injection quantity, they have not optimized the plunger parameters, cam profile, low-pressure fuel supply pressure, high-pressure fuel line specifications, and injector nozzle structure for the operating conditions of air-cooled diesel engines. The injection pressure is still difficult to exceed 1200 bar, and the improvement in atomization effect and adaptability to operating conditions is limited. These solutions cannot fundamentally solve the technical bottlenecks of traditional air-cooled diesel engines.

[0008] Therefore, in view of the above-mentioned defects in the existing technology, it is urgent to develop an electronically controlled high-pressure controllable injection scheme that is suitable for air-cooled diesel engines, so as to realize dynamic controllability of injection pressure and injection parameters under all operating conditions, and to balance high reliability, high performance and cost control, so as to solve the problems of poor fuel economy, insufficient emission performance and weak adaptability of traditional air-cooled diesel engines. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides an electronically controlled high-pressure controllable injection air-cooled diesel engine. This engine solves the problems of low injection pressure, uncontrollable injection parameters, and poor adaptability to operating conditions in traditional air-cooled diesel engines that use a mechanical plunger pump fuel supply system, which in turn leads to low combustion efficiency, high fuel consumption, and poor emission performance.

[0010] An electronically controlled high-pressure controllable injection air-cooled diesel engine includes an air-cooled diesel engine block and an electronically controlled high-pressure fuel injection system. The electronically controlled high-pressure fuel injection system uses an electronically controlled unit pump fuel supply system instead of a traditional mechanical plunger pump fuel supply system. The electronically controlled high-pressure fuel injection system includes an electronically controlled unit pump, an electronic control unit, a fuel supply cam, a low-pressure fuel circuit, a high-pressure fuel line, and fuel injectors. The electronic control unit is electrically connected to the control valve of the electronic control unit pump, and is used to precisely control the fuel injection quantity, fuel injection timing and fuel injection duration. The electronically controlled unit pump is equipped with a plunger and a plunger return spring, and the plunger and the oil supply cam form a transmission connection. The low-pressure oil circuit connects the low-pressure oil source to the plunger chamber of the electronically controlled unit pump, and the high-pressure oil pipe connects the high-pressure oil chamber of the electronically controlled unit pump to the injector. The injector is equipped with a needle valve, a spray nozzle, a needle valve return spring, and an oil outlet valve. The diesel engine achieves adjustable injection pressure and dynamic adaptive adjustment of injection parameters across all operating conditions through an electronically controlled high-pressure fuel injection system.

[0011] Preferably, the electronically controlled high-pressure fuel injection system uses an electronically controlled unit pump fuel supply system instead of a traditional mechanical plunger pump fuel supply system. The electronically controlled high-pressure fuel injection system includes an electronically controlled unit pump, an electronic control unit, a fuel supply cam, a low-pressure fuel line, a high-pressure fuel line, and a fuel injector. The electronic control unit is electrically connected to the control valve of the electronic control unit pump, and is used to precisely control the fuel injection quantity, fuel injection timing and fuel injection duration. The electronically controlled unit pump is equipped with a plunger and a plunger return spring, and the plunger and the oil supply cam form a transmission connection. The low-pressure oil circuit connects the low-pressure oil source to the plunger chamber of the electronically controlled unit pump, and the high-pressure oil pipe connects the high-pressure oil chamber of the electronically controlled unit pump to the injector. The injector is equipped with a needle valve, a spray nozzle, a needle valve return spring, and an oil outlet valve. The diesel engine achieves adjustable injection pressure and dynamic adaptive adjustment of injection parameters across all operating conditions through an electronically controlled high-pressure fuel injection system.

[0012] Preferably, the plunger diameter of the electronically controlled unit pump is 9mm~12mm, the preload of the plunger return spring is 230N, the stiffness is 23.125N / mm, the plunger diameter is preferably 11mm, and the rated oil supply camshaft speed is 1150r / min.

[0013] Preferably, the oil supply cam adopts a constant velocity cam profile, with an oil supply advance angle of -30°CA and an oil supply duration of 26.4°CA.

[0014] Preferably, the low-pressure oil circuit supply pressure is 3 bar to 6 bar, the low-pressure oil pump flow rate is 6 L / min, and the oil supply pressure is preferably 4 bar.

[0015] Preferably, the injector's injection pressure is 190 bar to 330 bar, and the injection pressure is preferably 270 bar; the injector's nozzle has a 5-hole structure, and the nozzle diameter is 0.22 mm to 0.30 mm, and the nozzle diameter is preferably 0.26 mm.

[0016] Preferably, the high-pressure oil pipe has an inner diameter of 1.6mm to 2.0mm and a length of 640mm to 940mm, with the inner diameter preferably being 1.8mm and the length preferably being 790mm.

[0017] Preferably, the air-cooled diesel engine is a 12-cylinder V-type turbocharged intercooled engine with a cylinder diameter of 125mm, a stroke of 130mm, a rated speed of 2300r / min, and a rated power of 406kW.

[0018] Compared with the prior art, the present invention has the following beneficial effects: In this invention, by setting up an electronically controlled high-pressure fuel injection system to replace the traditional mechanical plunger pump fuel supply system, precise control of injection pressure, injection quantity, injection timing and injection duration is achieved, solving the defect that the injection parameters of the traditional mechanical pump cannot be adjusted.

[0019] In this invention, by adopting a combination structure of an electronically controlled unit pump, a high-pressure fuel line, and an injector, a peak injection pressure of not less than 1200 bar under rated operating conditions is achieved, which effectively improves the fuel atomization quality and promotes complete combustion in the cylinder.

[0020] In this invention, the electronic control unit adaptively adjusts the injection parameters according to the diesel engine speed and load, enabling the diesel engine to obtain the optimal injection strategy in the entire operating range, thus significantly improving the adaptability to operating conditions.

[0021] In this invention, by optimizing the plunger diameter, fuel cam profile, low-pressure fuel circuit fuel supply pressure, and injector nozzle parameters, the consistency of fuel supply to each cylinder is improved, the standard deviation of cyclic fuel injection is reduced, and the stability of diesel engine operation is ensured.

[0022] In this invention, by increasing the injection pressure and optimizing the injection control, the minimum fuel consumption rate of the whole engine is effectively reduced, which can be reduced to as low as 221g / kW・h, significantly improving fuel economy.

[0023] In this invention, the in-cylinder combustion process is optimized by high-pressure controllable injection, which reduces the generation of incomplete combustion products, effectively improves the emission performance of diesel engines, and reduces pollutant emissions.

[0024] In this invention, by adapting to a 12-cylinder V-type turbocharged intercooled air-cooled diesel engine, an electronic fuel injection upgrade for a high-power diesel engine is achieved, taking into account both the reliability of the air-cooled diesel engine and the high-performance advantages of electronic fuel injection. Attached Figure Description

[0025] Figure 1 This invention relates to the fuel injection pressure curves of the mechanical fuel injection pump supply system at different diesel engine speeds. Figure 2 This is a one-dimensional simulation model of the air-cooled diesel engine electronically controlled unit pump fuel supply system of the present invention; Figure 3 This invention compares the simulated fuel injection pressure curve with experimental data. Figure 4 This invention provides the injection pressure curves corresponding to different plunger diameters at a camshaft speed of 1150 r / min. Figure 5 The differences in the offline fuel injection process of the three types of fuel supply cams of this invention; Figure 6This invention presents pressure change curves when the solenoid valve is not working under different low-pressure oil supply pressures. Figure 7 This invention relates to the differences in the oil injection process under different low-pressure oil circuits at a camshaft speed of 1150 r / min. Figure 8 This invention relates to the differences in the fuel injection process under different injector start-up pressures at a camshaft speed of 1150 r / min. Figure 9 This invention relates to the differences in the oil injection process under different nozzle diameters at a camshaft speed of 1150 r / min. Figure 10 This invention relates to the differences in the oil injection process under different high-pressure oil pipe diameters at a camshaft speed of 1150 r / min. Figure 11 This invention relates to the differences in the fuel injection process under different high-pressure oil pipe lengths at a camshaft speed of 1150 r / min. Figure 12 This is a comparison of the injection pressure and rate curves under different schemes of the present invention; Figure 13 It is a 3D model of an electrically controlled unit pump; Figure 14 It is the testing environment of the oil pump test bench; Figure 15 This is a waveform diagram of the oil pump test data; Figure 16 These are the test results of the unit pump oil supply characteristics and the consistency of each cylinder in this invention; Figure 17 This is the result of an external characteristic test of the replaced fuel supply system. Detailed Implementation

[0026] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0027] This invention aims to solve the problems of low injection pressure, poor precision, and uncontrollable injection system in existing air-cooled diesel engines by designing a controllable and precise high-pressure fuel injection system design method. This method aims to improve fuel atomization and combustion efficiency, enhance overall engine power, and reduce fuel consumption in a new type of air-cooled diesel engine. The fuel supply system parameter scheme can be obtained through parameter design formulas. Based on the calculated parameter range, parameters are combined, and the injection pressure, injection rate, and other parameters under each scheme are calculated through a fuel supply system simulation model. This allows for the selection of the optimal fuel supply system parameter scheme suitable for the air-cooled diesel engine.

[0028] Table 2, Parameters of Air-Cooled Diesel Engine (Mechanical Pump): Determine simulation parameters: When designing an electronically controlled high-pressure fuel supply system for an air-cooled diesel engine, simulation methods can be used to study the influence of key fuel supply system parameters, narrowing the parameter design range and reducing testing time and costs. Referring to the existing structure of electronically controlled unit pump fuel supply systems, a one-dimensional simulation model of the air-cooled diesel engine's electronically controlled unit pump fuel supply system is established using Siemens Amesim simulation software. Table 3. Parameters of the one-dimensional simulation model of the fuel supply system:

[0029] A comparison of the simulated and experimental injection pressure curves at 1150 r / min and a cyclic injection rate of 121 mg / cyc is shown below. Figure 3 As shown in Table 4, the simulation results and experimental results are in good agreement.

[0030] Table 4. Comparison of simulation results and experimental data:

[0031] Plunger diameter design: Simulation calculations were used to obtain the changes in injection pressure and circulating oil consumption at different plunger diameters under camshaft speeds of 1150 r / min and 400 r / min. Figure 4 As shown in Table 5.

[0032] Table 5. Fuel injection parameters for different plunger diameters at a camshaft speed of 1150 r / min:

[0033] Depend on Figure 4 It can be seen that at a camshaft speed of 1150 r / min, as the plunger diameter increases, the fuel accumulation process before the solenoid valve operates is significantly accelerated. This is because the increased plunger diameter increases the plunger cavity volume, and the increased oil filling in the cavity makes the oil pressure rise faster when the cam tappet rises. When the plunger diameter increases from 9 mm to 12 mm, the peak injection pressure increases from about 920 bar to about 1820 bar, the oil pressure rise rate increases, and the injection timing is also significantly advanced. This indicates that increasing the plunger diameter can increase the injection pressure and shorten the electro-hydraulic delay time. When the plunger diameter increases from 9 mm to 11 mm, the injection duration decreases from 31.5°CA to 29.0°CA, while when the plunger diameter increases from 11 mm to 12 mm, the injection duration slightly increases to 29.8°CA. This indicates that under an excessively large plunger diameter, the pressure in the high-pressure oil pipe may be too high, which may cause the needle valve to open prematurely and close late, resulting in a prolonged overall injection duration. Considering that excessive injection pressure at high speeds may reduce the reliability of the electronically controlled unit pump, the plunger diameter should not be too large.

[0034] Fuel supply cam profile design: Simulation calculations yielded the injection pressure and injection rate curves under three different fuel injection cam profiles at a camshaft speed of 1150 r / min, as shown below. Figure 5 As shown in Table 6, the injection parameters differ depending on the fuel injection cam profile. The rising speed of the tappet in the cam's working section varies with different cam profiles. When using a decelerating cam, the working section speed is higher, resulting in faster fuel pressure increase. Compared to constant velocity and accelerating cams, the needle valve opens earlier, leading to a faster initial injection rate and higher peak injection pressure. Therefore, for different fuel injection cam profiles, it is necessary to rationally select the fuel injection working section, aiming to place it within the high-speed movement area of ​​the cam tappet to achieve greater injection pressure and a shorter injection rate. Since the required injection timing and duration vary under different operating conditions, using a constant velocity cam increases the adjustable range of fuel injection parameters and improves fuel injection stability.

[0035] Table 6. Injection parameters for different fuel cam types at a camshaft speed of 1150 r / min:

[0036] Low-pressure oil circuit supply pressure design: Simulation calculations yielded the injection pressure and injection rate under different low-pressure oil circuit pressures at a camshaft speed of 1150 r / min, as follows: Figure 6 , Figure 7 As shown in Table 7, the slope of the rising section of the injection pressure curve increases with the increase of the low-pressure fuel supply pressure. The peak injection pressure also increases with the increase of the initial injection rate, indicating that increasing the low-pressure fuel supply pressure helps to accelerate the fuel accumulation process and improve the stability of the injection process. Therefore, when designing the low-pressure fuel supply pressure, it is necessary to ensure sufficient fuel filling in the plunger cavity. Based on this, the maximum low-pressure fuel supply pressure, where the peak injection pressure does not exceed the allowable value, should be selected to improve fuel supply stability.

[0037] Table 7. Injection parameters at different low-pressure oil circuit pressures when the camshaft speed is 1150 r / min:

[0038] Injector start-up pressure design: Simulation calculations yielded the injection pressure and rate curves at different injector initiation pressures for a camshaft speed of 1150 r / min, as shown below. Figure 8As shown in Table 8, the fuel injection data are as follows. The graph shows that as the injector initiation pressure increases, the rising segment of the injection pressure curve widens, and the peak injection pressure slightly increases. From the injection rate curve, it can be seen that when the injector initiation pressure is 190 bar, the needle valve opens prematurely, which is detrimental to stable fuel injection. As the initiation pressure increases, the needle valve opening time is delayed, and the premature opening phenomenon disappears. The injection duration gradually shortens as the initiation pressure increases, indicating that using a higher injector initiation pressure helps to increase the injection rate, shorten the injection duration, and promote combustion.

[0039] Table 8. Injection parameters at different low-pressure oil circuit pressures at a camshaft speed of 1150 r / min:

[0040] Injector orifice number and orifice diameter design: Simulation calculations yielded the injection pressure and rate curves for different nozzle diameters under the same cyclic fuel supply at a camshaft speed of 1150 r / min. Figure 9 As shown in Table 9, the fuel injection data is as follows. The figure shows that as the nozzle diameter increases, the peak injection pressure decreases significantly, while the injection rate increases significantly. This shortens the injection duration to achieve the target injection volume. Therefore, when selecting the nozzle diameter, both injection pressure and injection rate must be considered to ensure the quality of fuel atomization in the cylinder while shortening the injection duration to improve combustion.

[0041] Table 9. Fuel injection parameters at different nozzle diameters with a camshaft speed of 1150 r / min:

[0042] High-pressure oil pipe length and diameter design: The simulation yielded injection pressure and rate curves for different high-pressure fuel line diameters and lengths, as shown below. Figure 10 and Figure 11 As shown in Tables 10 and 11, the fuel injection data can be obtained by using a smaller high-pressure fuel pipe diameter, which can increase the peak injection pressure, but also slightly increases the injection duration to achieve the target cycle fuel consumption. Conversely, using a shorter high-pressure fuel pipe length can accelerate the fuel pressure rise, increase the peak pressure and injection advance angle, and also improve the injection rate. Therefore, in actual operation, it is necessary to select an appropriate high-pressure fuel pipe diameter and choose a shorter high-pressure fuel pipe for connection based on the positional relationship between the unit pump and each cylinder.

[0043] Table 10. Fuel injection parameters at different high-pressure oil pipe diameters with a camshaft speed of 1150 r / min:

[0044] Table 11. Injection parameters at different high-pressure oil pipe lengths with a camshaft speed of 1150 r / min:

[0045] Design method for parameters of electronically controlled high-pressure fuel supply system for air-cooled diesel engines: When designing the parameters of an electronically controlled high-pressure fuel supply system for an air-cooled diesel engine, a combination of empirical formulas and simulation calculations can be used. Based on target performance data such as target power and fuel consumption under rated operating conditions, different parameter combinations can be calculated. The feasibility of the scheme can be verified through simulation calculations, and the optimal parameter scheme can be selected. The main design parameters are shown in Table 12.

[0046] Table 12, Main design parameters of the oil supply system:

[0047] The process of designing and optimizing parameters for the fuel supply system of an air-cooled diesel engine: The established fuel supply system simulation model was used to calculate data such as peak injection pressure, injection rate, and circulating fuel quantity deviation corresponding to the rated operating conditions of the diesel engine under various schemes. Figure 12 As shown in Table 13, Scheme 2 can balance the differences in injection pressure, duration, and fuel volume in each cylinder, with the smallest standard deviation in fuel volume when using a 0.26mm orifice diameter. Based on the above calculations, subsequent machining of the fuel supply system and actual machine verification were carried out.

[0048] Table 13. Comparison of performance parameters under different fuel supply system parameter schemes:

[0049] Based on the previous design of the oil supply system parameters, the design and fabrication of the new electronically controlled unit pump oil supply system were completed. The 3D model is as follows: Figure 13 As shown, the fuel supply characteristics of the electronically controlled unit pump were tested on the fuel injection pump test bench, and data on the unit pump drive current, injection pressure, and injection rate were obtained. The test environment and test waveforms are shown in the figure. Figure 14 and Figure 15 As shown.

[0050] The test results of unit pump oil supply characteristics and cylinder consistency are as follows: Figure 16 As shown in the figure, when the electronically controlled unit pump is equipped with a 0.26mm orifice injector, the peak injection pressure can reach over 1200 bar at the rated camshaft speed and circulating fuel volume at the design point of 120 mg / cyc. When equipped with a 0.308mm orifice injector (the same orifice as the original mechanical pump fuel supply system), a peak injection pressure of over 1000 bar can be achieved. The results of the cylinder fuel supply consistency test show that the fuel supply deviation of the electronically controlled unit pump system is small. In summary, this electronically controlled unit pump can meet the requirements of air-cooled diesel engines, achieving high injection pressure and flexible and controllable timing.

[0051] After replacing the electronically controlled unit pump oil supply system, the performance changes after the replacement were analyzed through overall machine external characteristic tests. Figure 17 It can be seen that under the same external characteristic power target, the use of electronically controlled unit pump fuel supply system can achieve a lower fuel consumption rate, indicating that using electronically controlled unit pump fuel supply system to increase injection pressure and achieve controllable timing can effectively improve the in-cylinder combustion process of air-cooled diesel engine and improve thermal efficiency.

[0052] Design scheme for parameters of controllable high-pressure fuel injection system: To address the needs for improved environmental adaptability and increased power output of air-cooled diesel engines, a study on the design technology of controllable high-pressure fuel injection for air-cooled diesel engines was completed. Parameters are shown in Table 14, and the research results are as follows: 1) The fuel supply performance test of the air-cooled diesel engine was completed. The original mechanical plunger pump fuel supply system equipped with the air-cooled diesel engine has problems such as low injection pressure, uncontrollable injection timing and duration. It is proposed to adopt an electronically controlled high-pressure fuel supply system to improve fuel supply capacity and regulation capacity, improve fuel atomization in the cylinder, shorten the injection duration to concentrate the heat release of fuel combustion, and thus improve the overall power performance and environmental adaptability of the engine. 2) A one-dimensional simulation model of the electronically controlled high-pressure fuel supply system of an air-cooled diesel engine was established, and the influence of major fuel supply system parameters such as plunger diameter, fuel cam profile, low-pressure fuel circuit supply pressure, injector start-up pressure, number and diameter of injector nozzle holes, and diameter and length of high-pressure fuel line on fuel supply performance was determined. 3) A design method for controllable high-pressure fuel injection process was established. The parameters of the electronically controlled high-pressure fuel supply system of air-cooled diesel engine were designed by combining empirical formulas with simulation calculations. Based on the target power and fuel consumption under rated operating conditions, different combinations of parameters for low-pressure oil circuit, cam tappet and plunger chamber, high-pressure oil pipe and injector were calculated using empirical formulas. The fuel supply performance parameters of different schemes were calculated using a fuel supply system simulation model, and the optimal electronically controlled high-pressure fuel system parameter scheme was obtained.

[0053] 4) The design and fabrication of the electronically controlled high-pressure fuel system were completed based on the parameter scheme. The fuel supply characteristics and cylinder consistency of the electronically controlled high-pressure fuel system were tested on a fuel pump test bench, and the fuel supply performance meets the requirements of actual engine use. The overall engine external characteristic test results show that after replacing the electronically controlled high-pressure fuel system, the fuel consumption rate at the target power of the engine is lower than that of the original mechanical pump air-cooled engine. This indicates that using the electronically controlled high-pressure fuel system to achieve increased injection pressure and controllable injection timing can effectively improve the in-cylinder combustion process and increase thermal efficiency.

[0054] Table 14, Fuel Supply System Parameter Scheme: The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. An electronically controlled high-pressure controllable injection air-cooled diesel engine, comprising an air-cooled diesel engine block and an electronically controlled high-pressure fuel injection system, characterized in that, The electronically controlled high-pressure fuel injection system replaces the traditional mechanical plunger pump fuel injection system with an electronically controlled unit pump fuel supply system. The electronically controlled high-pressure fuel injection system includes an electronically controlled unit pump, an electronic control unit, a fuel supply cam, a low-pressure fuel line, a high-pressure fuel line, and fuel injectors. The electronic control unit is electrically connected to the control valve of the electronic control unit pump, and is used to precisely control the fuel injection quantity, fuel injection timing and fuel injection duration. The electronically controlled unit pump is equipped with a plunger and a plunger return spring, and the plunger and the oil supply cam form a transmission connection. The low-pressure oil circuit connects the low-pressure oil source to the plunger chamber of the electronically controlled unit pump, and the high-pressure oil pipe connects the high-pressure oil chamber of the electronically controlled unit pump to the injector. The injector is equipped with a needle valve, a spray nozzle, a needle valve return spring, and an oil outlet valve. The diesel engine achieves adjustable injection pressure and dynamic adaptive adjustment of injection parameters across all operating conditions through an electronically controlled high-pressure fuel injection system.

2. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The plunger diameter of the electronically controlled unit pump is 9mm~12mm, the preload of the plunger return spring is 230N, and the stiffness is 23.125N / mm.

3. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 2, characterized in that, The plunger diameter is preferably 11 mm, and the rated oil supply camshaft speed is 1150 r / min.

4. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The fuel supply cam adopts a constant velocity cam profile, with a fuel supply advance angle of -30°CA and a fuel supply duration of 26.4°CA.

5. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The low-pressure oil circuit has an oil supply pressure of 3 bar to 6 bar, and the low-pressure oil pump has a flow rate of 6 L / min, with the preferred oil supply pressure being 4 bar.

6. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The injector's injection pressure is 190 bar to 330 bar, and the preferred injection pressure is 270 bar.

7. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The injector has a 5-hole structure with a hole diameter of 0.22mm to 0.30mm, preferably 0.26mm.

8. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The high-pressure oil pipe has an inner diameter of 1.6mm~2.0mm and a length of 640mm~940mm, with the inner diameter preferably being 1.8mm and the length preferably being 790mm.

9. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The air-cooled diesel engine is a 12-cylinder V-type turbocharged intercooled engine with a cylinder diameter of 125mm, a stroke of 130mm, a rated speed of 2300r / min, and a rated power of 406kW.

10. The electronically controlled high-pressure controllable injection air-cooled diesel engine according to claim 1, characterized in that, The electronically controlled high-pressure fuel injection system has a peak injection pressure of no less than 1200 bar under rated operating conditions, and the minimum fuel consumption rate of the whole machine is reduced to 221 g / kW·h. The electronic control unit adaptively adjusts the injection parameters in real time according to the diesel engine speed and load.

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