A combustion chamber matching method for air-cooled diesel engines with offset injectors

Abstract

The invention discloses a combustion chamber matching method for an air-cooled diesel engine with an offset fuel injector, which relates to the technical field of engines. The method comprises the following steps: 1, determining overall engine parameters and combustion chamber-related parameters of an air-cooled diesel engine with a certain offset fuel injector; 2, determining a fuel injection angle and a circumferential spacing angle; 3, determining an oil beam injection distance of each spray hole; 4, determining an aperture of each spray hole; 5, establishing a three-dimensional model in Creo drawing software based on a given engine model; 6, importing the three-dimensional combustion chamber model in Creo drawing software into a pre-processing module in Converge software, correcting the geometric model, and setting parameters, physical properties, and component settings of the model through Case Setup Dock; 7, setting the spray holes of Spray modeling in the pre-processing module in Converge software, and running Converge software; 8, finding an output result in a Converge post-processing module, and calculating the indicated power of the engine after the combustion chamber matching method for the offset fuel injector is implemented; and 9, verifying the effect.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, in particular to a method for matching an offset fuel injector with a combustion chamber of an air-cooled diesel engine. Background Art

[0002] The quality of the fuel-air mixture and combustion structure within a diesel engine cylinder directly impacts engine performance, including power, fuel consumption, and emissions. Today's highly reinforced diesel engines are required to burn more fuel than standard diesel engines in a shorter combustion period. However, this shorter fuel-air mixing period and combustion duration make the fuel-air mixture quality even less guaranteed. This necessitates optimizing the fuel injection parameters and the combustion chamber to increase engine power. Fuel injection parameters include the number of injection holes, injection pinch, injection hole diameter, injection circumferential angle, and injection pressure. Currently, most known combustion chambers and injectors are centrally located, with the injector center positioned directly above the combustion chamber. Therefore, while matching methods for most symmetrical combustion chambers are similar, matching methods for offset injectors are relatively limited. In some air-cooled diesel engines, to ensure maximum cooling of the engine block, the injector position is shifted, resulting in an offset injector, meaning the injector center is not directly above the center of the combustion chamber. When matching the combustion chamber of an air-cooled diesel engine with offset injectors, it is necessary to consider the aperture size, injection angle, injection pressure, etc. of injection holes at different positions. Currently, a combustion chamber matching method for an air-cooled diesel engine with offset injectors has not been disclosed. Summary of the Invention

[0003] The purpose of the present invention is to provide a combustion chamber matching method for an air-cooled diesel engine with an offset injector, so as to solve the problem of the lack of combustion chamber matching methods for offset injectors in the design process of a high-intensity diesel engine combustion system in the prior art.

[0004] To achieve the above object, the present invention provides a method for matching an air-cooled diesel engine combustion chamber with an offset injector, comprising the following steps:

[0005] Step 1, determining the overall engine parameters and combustion chamber related parameters of an air-cooled diesel engine with a certain offset injector;

[0006] Step 2: Determine the fuel injection angle θ and the circumferential interval angle The fuel injection angle and circumferential spacing angle are determined by the impact position of the center of the fuel beam;

[0007] Step 3: Determine the oil jet distance of each nozzle hole; calculate the jet distance of each nozzle hole based on the relationship between the oil jet center impact position determined for each hole and the nozzle hole position;

[0008] Step 4: Determine the aperture of each nozzle hole;

[0009] Step 5: Create a 3D model based on the given engine model using Creo drawing software. Based on the cylinder head and piston configuration of the diesel engine, draw a 3D model of the combustion chamber when the piston is at top dead center.

[0010] Step 6: Import the 3D combustion chamber model from Creo into the pre-processing module in Converge, modify the geometry, and set the model parameters, properties, and components using the Case Setup Dock.

[0011] Step 7: Based on the fuel injection angle, circumferential spacing angle, and aperture size of each hole obtained in Steps 2 and 4, set the spray holes in the spray modeling of the pre-processing module in Converge software. After setting, run Converge software.

[0012] Step 8. Find the output results in the Converge post-processing module and calculate the engine indicated power after implementing the combustion chamber matching method of the offset injector;

[0013] Step 9: Effect verification: Compare the engine power after implementing the combustion chamber matching method with the offset injector and the engine power without the offset injector.

[0014] Preferably, the overall engine parameters include injection timing, injection pulse width, cylinder diameter, piston stroke, and in-cylinder pressure and temperature at the injection timing.

[0015] Preferably, the combustion chamber related parameters include the combustion chamber configuration and the position of the offset injector relative to the combustion chamber.

[0016] Preferably, the calculation expression of the fuel injection angle θ in step 2 is as follows:

[0017]

[0018] Where h represents the distance between the projection point of each hole onto plane α and the impact position of the center of the oil beam corresponding to each hole, and d represents the vertical distance from each hole to plane α.

[0019] Preferably, the circumferential spacing angle in step 2 is It is the angle between the projection point of each hole onto plane α and the line connecting the impact position of the center of the oil beam of the hole.

[0020] Preferably, the calculation expression of the oil jet injection distance of each nozzle hole in step 3 is as follows:

[0021]

[0022] Where d is the oil jet distance of each nozzle hole, in mm; x is the distance in the x-axis direction in the spatial coordinate system, in mm; y is the distance in the y-axis direction in the spatial coordinate system, in mm; and z is the distance in the z-axis direction in the spatial coordinate system, in mm.

[0023] Preferably, the process of determining the aperture of each nozzle hole in step 4 is as follows:

[0024] S41. Perform a constant volume combustion bomb experiment simulation in Converge software. Using the in-cylinder temperature and pressure at the time of injection as the initial conditions, determine the maximum liquid phase penetration distance for different pore diameters.

[0025] S42. Compare the maximum liquid phase penetration distance under different apertures obtained in S41 with the oil beam injection distance of each nozzle hole. Take 70% of the maximum liquid phase penetration distance as the oil beam injection distance to determine the aperture size of holes at different positions, and retain 30% of the energy to make the oil beam flow, so as to improve the oil-gas mixing quality.

[0026] Preferably, in S42, 70% of the maximum liquid phase penetration distance is taken as the oil beam injection distance to determine the aperture sizes of the holes at different positions. The calculation expression is as follows:

[0027] d2=d1*70%;

[0028] Where d1 is the maximum liquid phase penetration distance, in mm, and d2 is the oil beam injection distance, in mm.

[0029] Preferably, the expression for calculating the indicated power of the engine after the combustion chamber matching method of the offset injector is implemented in step 8 is as follows:

[0030]

[0031] Where, iV s is the displacement of the internal combustion engine, in L, p mi is the average indicated pressure in MPa, and n is the engine speed in r / min.

[0032] Therefore, the present invention adopts the above-mentioned method for matching the combustion chamber of an air-cooled diesel engine with an offset injector. Under the condition that the overall parameters of an air-cooled diesel engine with a certain offset injector and the relevant parameters of the combustion chamber are known, the injection angle, circumferential spacing angle and aperture of its different holes are determined, thereby determining its appropriate combustion chamber matching method, ensuring that the indicated power of the air-cooled diesel engine is further enhanced under the condition that the engine simply changes the injection parameters.

[0033] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is an overall flow chart of a method for matching an offset injector in an air-cooled diesel engine combustion chamber according to the present invention;

[0035] Figure 2 Schematic diagram of the collision position between each hole and the center of the oil beam in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0037] See also Figure 1 A method for matching an offset injector to an air-cooled diesel engine combustion chamber comprises the following steps:

[0038] Step 1: Determine overall engine parameters and combustion chamber-related parameters of an air-cooled diesel engine with a certain offset injector; wherein the overall engine parameters include injection timing, injection pulse width, cylinder diameter, piston stroke, and in-cylinder pressure and temperature at the injection timing; and the combustion chamber-related parameters include combustion chamber configuration and the position of the offset injector relative to the combustion chamber;

[0039] Step 2: Determine the fuel injection angle θ and the circumferential interval angle The fuel injection angle and circumferential interval angle are determined by the impact position of the fuel beam center. Therefore, the appropriate fuel injection angle can be determined by simply determining the impact position of the fuel beam center. This ensures that the impact positions of the fuel beam centers are evenly distributed on the piston, and that the centers of the fuel beams form a plane α.

[0040] The calculation expression of the fuel injection angle θ is as follows:

[0041]

[0042] Where h represents the distance between the projection point of each hole onto plane α and the impact position of the center of the oil beam corresponding to each hole, and d represents the vertical distance from each hole to plane α.

[0043] Circumferential spacing angle It is the angle between the projection point of each hole onto plane α and the line connecting the impact position of the center of the oil beam of the hole.

[0044] Step 3. Determine the oil beam injection distance of each nozzle hole. Since the research object is a combustion chamber with an offset injector, the injection distances of the oil beams of different holes in the combustion chamber will be different. If the distal hole diameter is too small, the oil beam penetration distance will be too small, resulting in the oil beam not hitting the piston, not utilizing the distal air, and the oil-gas mixing quality in the cylinder deteriorating, which reduces power. If the proximal hole diameter is too large, the oil beam penetration distance will be too large and the oil volume will be too much, causing the oil beam to gather on the piston surface, which reduces power. Based on the relationship between the oil beam center impact position and the nozzle position determined for each hole, the injection distance of each nozzle hole is calculated. The injection distance refers to the distance between the injection hole and the appropriate oil beam center impact position when the piston is at the top dead center. The specific calculation expression is as follows:

[0045]

[0046] Where d is the oil jet distance of each nozzle hole, in mm; x is the distance in the x-axis direction in the spatial coordinate system, in mm; y is the distance in the y-axis direction in the spatial coordinate system, in mm; and z is the distance in the z-axis direction in the spatial coordinate system, in mm.

[0047] Step 4: Determine the aperture of each nozzle; the specific process is as follows:

[0048] S41. Perform a constant volume combustion bomb experiment simulation in Converge software. Using the in-cylinder temperature and pressure at the time of injection as the initial conditions, determine the maximum liquid phase penetration distance for different pore diameters.

[0049] S42. Compare the maximum liquid phase penetration distances for different apertures obtained in S41 with the oil jet distances of each nozzle hole. 70% of the maximum liquid phase penetration distance is taken as the oil jet distance to determine the aperture sizes of the holes at different locations. 30% of the energy is retained to create oil jet plumes, thereby improving the oil-gas mixing quality. The calculation expression for determining the aperture sizes of the holes at different locations by taking 70% of the maximum liquid phase penetration distance as the oil jet distance is as follows:

[0050] d2=d1*70%;

[0051] Where d1 is the maximum liquid phase penetration distance, in mm, and d2 is the oil beam injection distance, in mm.

[0052] Step 5: Create a 3D model based on the given engine model using Creo drawing software. Based on the cylinder head and piston configuration of the diesel engine, draw a 3D model of the combustion chamber when the piston is at top dead center.

[0053] Step 6: Import the 3D combustion chamber model from Creo into the pre-processing module in Converge, modify the geometry, and set the model parameters, physical properties, and component settings using the Case Setup Dock.

[0054] Step 7: Based on the fuel injection angle, circumferential spacing angle, and aperture size of each hole obtained in Steps 2 and 4, set the spray holes in the spray modeling of the pre-processing module in the Converge software. After setting, run the Converge software.

[0055] Step 8. Find the output results in the Converge post-processing module and calculate the engine indicated power after implementing the combustion chamber matching method of the offset injector; the specific expression is as follows:

[0056]

[0057] Where, iV s is the displacement of the internal combustion engine, in L, p mi is the average indicated pressure in MPa, and n is the engine speed in r / min.

[0058] Step 9, effect verification: Comparing the engine power after implementing the combustion chamber matching method with the offset injector and the engine power without the offset injector, it is found that the engine power of the combustion chamber matching method with the offset injector is higher than the original engine power.

[0059] Example

[0060] Take the combustion chamber of a 240KW four-stroke air-cooled diesel engine with offset injectors as an example. Its design compression ratio is 17, the number of cylinders is 6, and the number of injection holes is 6. According to step 1, determine the overall parameters of the engine and combustion chamber related parameters of a certain injector offset air-cooled diesel engine; according to step 2, first determine the appropriate center impact position of the oil beam, then determine the fuel injection angle and circumferential spacing angle of each hole, and then determine the fuel injection angle and circumferential spacing angle of each hole. Figure 2 As shown, since the holes are very close to each other, the positions of the holes are uniformly set as point A in the three-dimensional diagram, and the center of the oil beam of each hole hits the position C n (n=1, 2, 3, 4, 5, 6) are evenly distributed on the piston surface, forming a plane α, and the projection point of point A on plane α is point B. From this three-dimensional diagram, we can know the fuel injection angle 2∠BAC of each hole n(n=1, 2, 3, 4, 5, 6) are 141°, 133°118°, 118°, 133°, 140° respectively, and the circumferential spacing angles of each hole ∠C3BC2, ∠C2BC1, ∠C1BC6, ∠C6BC5, ∠C5BC4, ∠C4BC3 are 50.5°, 65.2°, 81.8°, 65.2°, 50.5°, 46.8° respectively; according to step 3, the oil beam injection distance of each nozzle hole is determined, and the oil beam injection distance of each nozzle hole is 42.2mm, 35.8mm, 28.2mm, 28.5mm, 35.8mm respectively. mm, 42.2 mm; according to step 4, a constant volume combustion bomb experiment simulation is performed in Converge software. In particular, the initial conditions are the temperature and pressure in the cylinder of the diesel engine at the time of injection. The maximum liquid phase penetration distance under different apertures is obtained, and 70% of the maximum liquid phase penetration distance is taken as the oil beam injection distance to select the appropriate aperture size of the holes at different positions; according to step 5, a 3D model is established in Creo drawing software based on the given model; according to step 6, the 3D model of the combustion chamber in Creo drawing software is imported into the pre-processing module of Converge software, the geometric model is modified, and the case Setup Dock sets the model and parameters; according to step 7, the injection angle, circumferential spacing angle and aperture size of each hole are set; according to step 8, it is concluded that the engine indicated power after implementing the combustion chamber matching method with injector offset is 249KW; according to step 9, the engine power after implementing the combustion chamber matching method with injector offset is compared with the engine power without the combustion chamber matching method with injector offset, and it is found that the engine power of 249KW after implementing the combustion chamber matching method with injector offset is higher than the original engine power of 240KW.

[0061] Therefore, the present invention adopts the above-mentioned method for matching the combustion chamber of an air-cooled diesel engine with an offset injector. Under the condition that the overall parameters of an air-cooled diesel engine with a certain offset injector and the relevant parameters of the combustion chamber are known, the injection angle, circumferential spacing angle and aperture of its different holes are determined, thereby determining its appropriate combustion chamber matching method, ensuring that the indicated power of the air-cooled diesel engine is further enhanced under the condition that the engine simply changes the injection parameters.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for matching the combustion chamber of an air-cooled diesel engine with an offset injector, characterized in that: The following steps are involved: Step 1, determining the overall engine parameters and combustion chamber related parameters of an air-cooled diesel engine with a certain offset injector; Step 2: Determine the fuel injection angle θ and the circumferential interval angle The fuel injection angle and circumferential spacing angle are determined by the impact position of the center of the fuel beam; Step 3: Determine the oil jet distance of each nozzle hole; calculate the jet distance of each nozzle hole based on the relationship between the oil jet center impact position determined for each hole and the nozzle hole position; Step 4: Determine the aperture of each nozzle hole; Step 5: Create a 3D model based on the given engine model using Creo drawing software. Based on the cylinder head and piston configuration of the diesel engine, draw a 3D model of the combustion chamber when the piston is at top dead center. Step 6: Import the 3D combustion chamber model from Creo into the pre-processing module in Converge, modify the geometry, and set the model parameters, physical properties, and component settings using the Case Setup Dock. Step 7: Based on the fuel injection angle, circumferential spacing angle, and aperture size of each hole obtained in Steps 2 and 4, set the spray holes in the spray modeling of the pre-processing module in the Converge software. After setting, run the Converge software. Step 8. Find the output results in the Converge post-processing module and calculate the engine indicated power after implementing the combustion chamber matching method of the offset injector; Step 9: Effect verification: Compare the engine power after implementing the combustion chamber matching method with the offset injector and the engine power without the offset injector.

2. The method for matching an air-cooled diesel engine combustion chamber with an offset injector according to claim 1, characterized in that: The overall engine parameters include injection timing, injection pulse width, cylinder diameter, piston stroke, and in-cylinder pressure and temperature at the injection timing.

3. The method for matching an air-cooled diesel engine combustion chamber with an offset injector according to claim 2, characterized in that: Combustion chamber related parameters include the combustion chamber configuration and the position of the offset injector relative to the combustion chamber.

4. The method for matching an air-cooled diesel engine combustion chamber with an offset injector according to claim 3, characterized in that: The calculation expression of the fuel injection angle θ in step 2 is as follows: Where h represents the distance between the projection point of each hole onto plane α and the impact position of the center of the oil beam corresponding to each hole, and d represents the vertical distance from each hole to plane α.

5. The method for matching an air-cooled diesel engine combustion chamber with an offset injector according to claim 4, characterized in that: Circumferential spacing angle in step 2 It is the angle between the projection point of each hole onto plane α and the line connecting the impact position of the center of the oil beam of the hole.

6. The method for matching an offset injector to an air-cooled diesel engine combustion chamber according to claim 5, characterized in that: The calculation expression of the oil beam injection distance of each nozzle in step 3 is as follows: Where d is the oil jet distance of each nozzle hole, in mm; x is the distance in the x-axis direction in the spatial coordinate system, in mm; y is the distance in the y-axis direction in the spatial coordinate system, in mm; and z is the distance in the z-axis direction in the spatial coordinate system, in mm.

7. The method for matching an air-cooled diesel engine combustion chamber with an offset injector according to claim 6, characterized in that: The process of determining the aperture of each nozzle in step 4 is as follows: S41. Perform a constant volume combustion bomb experiment simulation in Converge software. Using the in-cylinder temperature and pressure at the time of injection as the initial conditions, determine the maximum liquid penetration distance for different pore diameters. S42. Compare the maximum liquid phase penetration distances under different apertures obtained in S41 with the oil beam injection distances of each nozzle hole, and determine the aperture sizes of the holes at different positions by taking 70% of the maximum liquid phase penetration distance as the oil beam injection distance.

8. The method for matching an air-cooled diesel engine combustion chamber with an offset injector according to claim 7, characterized in that: In S42, the calculation expression for determining the aperture size of holes at different positions is as follows: 70% of the maximum liquid phase penetration distance is equal to the oil jet distance. d2=d1*70%; Where d1 is the maximum liquid phase penetration distance, in mm, and d2 is the oil beam injection distance, in mm.

9. The method for matching the combustion chamber of an air-cooled diesel engine with an offset injector according to claim 8, characterized in that: The expression for calculating the indicated power of the engine after implementing the combustion chamber matching method of the offset injector in step 8 is as follows: Where, iV s is the displacement of the internal combustion engine, in L, p mi is the average indicated pressure in MPa, and n is the engine speed in r / min.

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