Matching method for combustion chamber of air-cooled diesel engine with offset fuel injector

Abstract

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

Description

Technical Field

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

[0002] The quality of oil-gas mixture and combustion organization in the cylinder of diesel engine directly affect the relevant performance of diesel engine such as power, fuel consumption and emission. Nowadays, high-strength diesel engine requires to burn more fuel than ordinary diesel engine in a shorter combustion period, and the shorter oil-gas mixture period and combustion period make the oil-gas mixture quality less guaranteed, which requires us to optimize the matching of fuel injection parameters and combustion chamber to increase the power of diesel engine. Fuel injection parameters include the number of fuel injection holes, fuel injection clamp, fuel injection aperture, fuel injection circumferential angle, fuel injection pressure, etc., and most of the known combustion chambers and injectors are centrally distributed, that is, the center of the injector is located directly above the combustion chamber, so the matching methods for most symmetrical combustion chambers are similar, but there are relatively few matching methods for the combustion chamber of offset injectors. For some air-cooled diesel engines, in order to ensure that the cooling wind can cool the engine body to the maximum extent, the position of the injector will be moved, resulting in the injector offset, that is, the center of the injector is not located directly above the center of the combustion chamber. For combustion chamber matching of an air-cooled diesel engine with offset fuel injectors, it is necessary to consider the aperture size of fuel injection holes at different positions, fuel injection angle, fuel injection pressure, etc. Currently, a combustion chamber matching method for an air-cooled diesel engine with offset fuel 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 fuel injector, so as to solve the problem of the lack of combustion chamber matching methods for offset fuel injectors in the design process of a high-intensification 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 fuel injector, comprising the following steps:

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

[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, determining the oil beam spray distance of each spray hole; calculating the spray distance of each spray hole according to the relationship between the oil beam center impact position determined for each hole and the spray hole position;

[0008] Step 4, determine the aperture of each nozzle hole;

[0009] Step 5: Based on the given engine model, a 3D model is established on the Creo drawing software. According to the cylinder head and piston configuration of the diesel engine, a 3D model of the combustion chamber when the piston is at the top dead center is drawn;

[0010] Step 6: Import the 3D model of the combustion chamber in Creo drawing software into the pre-processing module in Converge software, modify the geometric model, and set the parameters, physical properties, and component settings of the model through Case Setup Dock (parameter setting panel);

[0011] Step 7, according to the fuel injection angle, circumferential spacing angle and aperture size of each hole obtained in step 2 and step 4, set the spray hole of the spray modeling of the pre-processing module in the Converge software, and run the Converge software after the setting is completed;

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

[0013] Step 9, effect verification: compare the engine power after the combustion chamber matching method of the offset fuel injector is implemented with the engine power of the combustion chamber matching method without the offset fuel injector.

[0014] Preferably, the overall engine parameters include injection timing, injection pulse width, cylinder diameter, piston stroke, and 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 to 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] Wherein, d is the oil jet injection 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 constant volume combustion bomb experiment simulation in Converge software. Under the initial conditions of the in-cylinder temperature and pressure of the diesel engine at the time of fuel injection, obtain the maximum liquid phase penetration distance under different apertures.

[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, and take 70% of the maximum liquid phase penetration distance equal to 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 vortex 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 holes at different positions. The calculation expression is as follows:

[0027] d2 = d1 * 70%;

[0028] Where d1 is the maximum liquid penetration distance, in mm, and d2 is the oil jet 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 air-cooled diesel engine combustion chamber matching method 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 different holes are determined, thereby determining its appropriate combustion chamber matching method, thereby 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 It is an overall flow chart of a method for matching an air-cooled diesel engine combustion chamber with an offset fuel injector according to the present invention;

[0035] Figure 2 It is a 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 invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] See also Figure 1 , a method for matching an air-cooled diesel engine combustion chamber with an offset injector, comprising the following steps:

[0038] Step 1, determining the overall parameters of an air-cooled diesel engine with a certain offset injector and the combustion chamber related parameters; wherein the overall parameters of the engine include injection timing, injection pulse width, cylinder diameter, piston stroke, cylinder pressure and temperature at the injection timing; the combustion chamber related parameters include the 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 center of the fuel beam. Therefore, the appropriate fuel injection angle can be determined by simply determining the impact position of the center of the fuel beam, ensuring that the impact positions of the centers of each fuel beam are evenly distributed on the piston and that the centers of each fuel beam 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 to 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 the combustion chamber with the injector offset, the injection distance 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, and the distal air cannot be used, the oil-gas mixing quality in the cylinder will deteriorate, and the power will be reduced; while the proximal hole diameter is too large, resulting in the oil beam penetration distance being too large and the oil volume being too much, causing the oil beam to gather on the piston surface, and the power will be reduced. According to the relationship between the oil beam center impact position and the nozzle position determined by each hole, the injection distance of each nozzle hole is calculated, and 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] Wherein, d is the oil jet injection 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 hole; the specific process is as follows:

[0048] S41. Perform constant volume combustion bomb experiment simulation in Converge software. Under the initial conditions of the in-cylinder temperature and pressure of the diesel engine at the time of fuel injection, obtain the maximum liquid phase penetration distance under different apertures.

[0049] 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 equal to the oil beam injection distance to determine the aperture size of the 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. The calculation expression for taking 70% of the maximum liquid phase penetration distance equal to the oil beam injection distance to determine the aperture size of the holes at different positions is as follows:

[0050] d2 = d1 * 70%;

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

[0052] Step 5: Based on the given engine model, a 3D model is established on the Creo drawing software. According to the cylinder head and piston configuration of the diesel engine, a 3D model of the combustion chamber when the piston is at the top dead center is drawn;

[0053] Step 6: Import the 3D model of the combustion chamber in Creo drawing software into the pre-processing module in Converge software, modify the geometric model, and set the parameters, physical properties, and component settings of the model through Case Setup Dock;

[0054] Step 7, according to the fuel injection angle, circumferential spacing angle and aperture size of each hole obtained in Step 2 and Step 4, set the spray hole of Spray modeling in the pre-processing module of Converge software, and run Converge software after setting;

[0055] Step 8. Find the output result in the Converge post-processing module and calculate the engine indicated power after the combustion chamber matching method of the offset injector is implemented; 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 the combustion chamber matching method with the offset injector is implemented with the engine power with the combustion chamber matching method without the offset injector, it is found that the engine power with the combustion chamber matching method with the offset injector is higher than the original engine power.

[0059] Example

[0060] Take a combustion chamber of a four-stroke air-cooled diesel engine with an offset injector and an indicated power of 240KW as an example. Its design compression ratio is 17, the number of cylinders is 6, and the number of spray holes is 6. According to step 1, determine the overall parameters of a certain injector offset air-cooled diesel engine and the relevant parameters of the combustion chamber; according to step 2, first determine the appropriate center impact position of the oil beam, and then determine the fuel injection angle and circumferential spacing angle of each hole. Figure 2 As shown in the figure, 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 graph, 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; the oil beam injection distance of each nozzle hole is determined according to step 3, and the oil beam injection distances of each nozzle hole are 42.2mm, 35.8mm, 28.2mm, 28.5mm, 35.8 mm, 42.2mm; according to step 4, a constant volume combustion bomb experiment simulation is performed in Converge software. In particular, the initial conditions are the cylinder temperature and pressure of the diesel engine at the time of fuel injection, and the maximum liquid phase penetration distance under different apertures is obtained. 70% of the maximum liquid phase penetration distance is taken as the oil beam injection distance to select the appropriate aperture size of holes at different positions; according to step 5, a three-dimensional model is established on the Creo drawing software based on the given model; according to step 6, the three-dimensional model of the combustion chamber in the Creo drawing software is imported into the pre-processing module of the 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 indicated power of the engine after the implementation of the combustion chamber matching method with the injector offset is 249KW; according to step 9, the engine power after the implementation of the combustion chamber matching method with the injector offset is compared with the engine power without the combustion chamber matching method with the injector offset, and it is found that the engine power of 249KW after the implementation of the combustion chamber matching method with the injector offset is higher than the original engine power of 240KW.

[0061] Therefore, the present invention adopts the above-mentioned air-cooled diesel engine combustion chamber matching method 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 different holes are determined, thereby determining its appropriate combustion chamber matching method, thereby 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 solution of the present invention rather than to limit it. 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 solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution 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 parameters of an air-cooled diesel engine with a certain offset injector and the parameters related to the combustion chamber; 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, determining the oil beam spray distance of each spray hole; calculating the spray distance of each spray hole according to the relationship between the oil beam center impact position determined by each hole and the spray hole position; Step 4, determine the aperture of each nozzle hole; Step 5: Based on the given engine model, a 3D model is established on the Creo drawing software. According to the cylinder head and piston configuration of the diesel engine, a 3D model of the combustion chamber when the piston is at the top dead center is drawn; Step 6: Import the 3D model of the combustion chamber in Creo drawing software into the pre-processing module in Converge software, modify the geometric model, and set the parameters, physical properties, and component settings of the model through Case Setup Dock; Step 7, according to the fuel injection angle, circumferential spacing angle and aperture size of each hole obtained in Step 2 and Step 4, set the spray hole of Spray modeling in the pre-processing module of Converge software, and run Converge software after setting; Step 8. Find the output results in the Converge post-processing module and calculate the engine indicated power after the combustion chamber matching method of the offset injector is implemented; Step 9, effect verification: compare the engine power after the combustion chamber matching method with the offset fuel injector is implemented with the engine power without the offset fuel injector combustion chamber matching method.

2. The method for matching the combustion chamber of an air-cooled diesel engine 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 cylinder pressure and temperature at the injection timing.

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

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

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

Images