Optimization design method for oil-gas separator of high-power diesel engine

Abstract

The invention relates to the technical field of diesel engines, in particular to an optimal design method for an oil-gas separator of a high-power diesel engine. The method comprises the following steps: determining demand analysis of the oil-gas separator; determining a separation technology and a structure of an oil-gas separator based on the demand analysis; determining detailed parameters of the oil-gas separator; simulation and analysis are carried out, and then part design and strength and safety evaluation are carried out. The blow-by amount of the crankcase of the diesel engine is accurately designed; oil-gas separator design or model selection is optimized; the filtering efficiency of the oil-gas separator is optimized; the emission performance of the diesel engine is optimized; the engine oil consumption rate of the diesel engine is reduced; and economic benefits and social benefits of the diesel engine are improved.

Description

Technical Field

[0001] The invention relates to the technical field of diesel engines, and in particular to an optimization design method for an oil-gas separator of a high-power diesel engine. Background Art

[0002] For high-power diesel engines for locomotives, the main sources of crankcase blowby during normal operation include two aspects: First, the high-pressure working gas in the cylinder will inevitably pass through the gap between the cylinder liner, piston ring and piston into the diesel engine crankcase; Second, with the continuous improvement of supercharging technology and the continuous increase in supercharging ratio, a small amount of high-pressure gas will enter the crankcase through the oil circuit of the supercharger. If the blowby gas is not discharged in time, the crankcase pressure will continue to rise, which will cause oil and air leakage in the corresponding sealing parts of the crankcase, and increase the piston pumping loss. More seriously, it will cause power reduction and seriously affect the normal operation of the diesel engine. Therefore, the crankcase ventilation system is indispensable.

[0003] At present, the crankcase ventilation system of high-power diesel engines is mainly divided into open crankcase ventilation system and closed crankcase ventilation system. The open crankcase ventilation system discharges the crankcase blowby gas into the atmosphere, while the closed crankcase ventilation system introduces the crankcase blowby gas into the diesel engine intake and returns to the cylinder with the intake air for combustion. Crankcase blowby gas mainly comes from the cylinder, which not only contains gaseous pollutants such as HC and suspended particles such as carbon soot, but also includes a large amount of engine oil taken away when it passes through the lubricating oil film on the cylinder liner during the process of blowing out between the piston ring and the cylinder liner. Moreover, whether it is cylinder blowby gas or supercharger blowby gas, its temperature is relatively high, which will further promote the evaporation of a large amount of engine oil in the crankcase, and finally cause the crankcase blowby gas to contain a large amount of engine oil, and it mainly exists in the form of engine oil droplets between 0 and 10μm. If an open crankcase ventilation system is used, it will directly pollute the atmospheric environment and greatly increase the particle pollutant emission value of the diesel engine. If a closed crankcase ventilation system is used, on the one hand, the oil and particulate matter in the blowby gas may adhere to the inside of the supercharger, intercooler and other components in the diesel engine intake system, seriously affecting the performance of these components. On the other hand, the oil cannot be completely burned and enters the cylinder with the intake air, which will have a negative impact on the diesel engine's emissions.

[0004] As green environmental protection becomes the mainstream development direction, diesel engine emissions have gradually become the focus of people's attention. Therefore, in order to reduce or even avoid the negative impact of crankcase blowby on diesel engine emissions, an efficient oil-gas separator must be used in the crankcase ventilation system to separate the oil droplets in the crankcase blowby. In addition, the filtered oil is returned to the oil pan, which can also greatly reduce the oil consumption of the diesel engine.

[0005] An efficient oil-gas separator is to ensure that the diesel engine can effectively filter out the oil components in the crankcase blowby gas during its entire emission effective life cycle, and reduce its impact on diesel engine emissions. Due to the different diesel engines, the amount of crankcase blowby gas varies according to their respective structures, sizes, performance and other factors. Therefore, in order to ensure the efficiency of the oil-gas separator, its design or selection size or quantity (using multiple oil-gas separators in parallel) is closely related to the crankcase blowby gas volume. As a locomotive diesel engine, due to the limitation of the locomotive installation space, the main limiting factor in the design or selection of its oil-gas separator is the size or quantity of the oil-gas separator. Therefore, the determination of the crankcase blowby gas volume is the key to the design or selection of the oil-gas separator. Reasonable and accurate design of the crankcase blowby gas volume can ensure that the oil-gas separator achieves efficient oil filtration efficiency in a limited space.

[0006] For the design of crankcase ventilation system of automotive diesel engine, the calculation formula of crankcase blowby volume under rated working condition is:

[0007] In the formula A ——blowby volume; K ——Ratio of blowby volume to fresh air impulse in cylinder, for cylinder diameter D Car firewood with a diameter less than 100 mm; Oil engine, K =0.01~0.025, for D Diesel engines ≥100mm, K =0.005~0.015; V h - engine displacement; n——engine speed; ——The engine's charging efficiency.

[0008] The existing scheme is suitable for early automotive diesel engines, which have a high rated speed, which is more than 50% higher than the rated speed of current locomotive diesel engines, and they do not have the high boost ratio supercharger commonly used in current locomotive diesel engines. Therefore, the amount of blowby calculated by this empirical formula deviates greatly from the actual measured crankcase blowby of current locomotive diesel engines. In addition, it does not take into account the possible changes in the amount of blowby of the engine during its entire emission effective life cycle. In summary, this scheme cannot meet the design requirements for the amount of crankcase blowby of locomotive diesel engines that meet current emission standards. Summary of the invention

[0009] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides an optimization design method for an oil-gas separator of a high-power diesel engine.

[0010] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions: In a first aspect, in one embodiment provided by the present invention, a method for optimizing the design of a high-power diesel engine oil-gas separator is provided, the method comprising the following steps: Determine the demand analysis of oil and gas separator; Determine the separation technology and the structure of the oil-gas separator based on the demand analysis; Determine the detailed parameters of the oil-gas separator, where the maximum crankcase blowby volume of the oil-gas separator must meet the following formula: , In the formula, —Maximum crankcase blowby volume (l / min); —Rated speed of diesel engine (r / min); —Scavenging air pressure of diesel engine cylinder (bar.abs); —Scavenging air temperature of diesel engine cylinder (K); —Displacement of diesel engine (L); —Impulse coefficient of diesel engine; —Type coefficient of turbocharging system of diesel engine; Conduct simulations and analyses leading to component design, strength and safety assessments.

[0011] As a further solution of the present invention, the determination of the demand analysis of the oil-gas separator includes: Determine the oil and gas flow rate that the separator needs to handle; Analyze the specific properties of oil and gas; Determine separation efficiency requirements; Consider the operating pressure and temperature range.

[0012] As a further embodiment of the present invention, the separation technology includes gravity separation, centrifugal separation or filtration separation.

[0013] As a further solution of the present invention, the structure of the oil-gas separator includes vertical, horizontal or spherical.

[0014] As a further solution of the present invention, the rated speed of the diesel engine ranges from 1000 r / min to 2000 r / min.

[0015] As a further embodiment of the present invention, the impulse coefficient of the diesel engine The minimum value range is 0.55.

[0016] As a further solution of the present invention, a single-stage supercharging system, the supercharging system type coefficient of the diesel engine The value is 1.

[0017] As a further solution of the present invention, a two-stage supercharging system, the supercharging system type coefficient of the diesel engine The value is 1.2857.

[0018] The technical solution provided by the present invention has the following beneficial effects: The present invention accurately designs the diesel engine crankcase blowby volume; optimizes the oil-gas separator design or selection; optimizes the oil-gas separator filtering efficiency; optimizes the diesel engine emission performance; reduces the diesel engine oil consumption rate; and improves the diesel engine's economic and social benefits.

[0019] These and other aspects of the present invention will be more clearly understood in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory and cannot limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0021] Figure 1 The present invention is a flowchart of a method for optimizing the design of a high-power diesel engine oil-gas separator according to an embodiment of the present invention.

[0022] Figure 2 The figure is a curve diagram showing the change of the cumulative running time of the crankcase blowby amount of a diesel engine in one embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0024] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may also be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0025] It should be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0026] Specifically, the embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0027] For high-power locomotive diesel engines, the maximum crankcase blowby volume of the diesel engine is optimized and designed by comprehensively considering the structure of the diesel engine, the emission control technology used, and the wear of the diesel engine related parts during the entire emission effective life cycle. The maximum crankcase blowby volume that is optimized and designed can more accurately reflect the actual value of the diesel engine. The design or selection of the oil-gas separator based on this can ensure that the oil-gas separation efficiency is high within the limited installation space of the locomotive diesel engine, and reduce or even avoid its impact on diesel engine emissions. If the designed crankcase blowby volume is too large, the volume of the oil-gas separator will be too large, or the filtration efficiency of the oil-gas separator will decrease; if the designed crankcase blowby volume is too small, the filtration efficiency of the oil-gas separator will be seriously affected, and the oil consumption rate will increase, which will seriously affect the emission performance of the diesel engine. Therefore, the present invention proposes an optimization design method for a high-power diesel engine oil-gas separator.

[0028] See also Figure 1 , Figure 1 Flow chart of an optimization design method for a high-power diesel engine oil-gas separator provided by an embodiment of the present invention. Figure 1 As shown, the optimization design method of the high-power diesel engine oil-gas separator includes steps S10 to S40.

[0029] S10. Determine the demand analysis for oil-gas separator.

[0030] In an embodiment of the present invention, the step S10, determining the demand analysis of the oil-gas separator, includes: Determine the oil and gas flow rate that the separator needs to handle; Analyze the specific properties of oil and gas; Determine separation efficiency requirements; Consider the operating pressure and temperature range.

[0031] S20, determining the separation technology and the structure of the oil-gas separator based on the demand analysis; In an embodiment of the present invention, the separation technique includes gravity separation, centrifugal separation or filtration separation.

[0032] In the embodiment of the present invention, the structure of the oil-gas separator includes vertical, horizontal or spherical.

[0033] S30, determining detailed parameters of the oil-gas separator, wherein the maximum crankcase blowby volume of the oil-gas separator must satisfy the following formula: , In the formula, —Maximum crankcase blowby volume (l / min); —Rated speed of diesel engine (r / min); —Scavenging air pressure of diesel engine cylinder (bar.abs); —Scavenging air temperature of diesel engine cylinder (K); —Displacement of diesel engine (L); —Impulse coefficient of diesel engine; —The turbocharging system type coefficient of the diesel engine, the single-stage turbocharging system takes the value of 1, and the two-stage turbocharging system takes the value of 1.2857.

[0034] In the embodiment of the present invention, the calibrated speed of the diesel engine ranges from 1000 r / min to 2000 r / min.

[0035] In the embodiment of the present invention, the scavenging pressure value range of the cylinder under the diesel engine calibration tool can reach up to 8 bar.abs, which covers the ultra-high boost pressure including the two-stage boost system.

[0036] In the embodiment of the present invention, the impulse coefficient of the diesel engine is The minimum value range can reach 0.55 (the general four-stroke turbocharged diesel engine has a value range of 0.9-105), which covers the performance changes brought about by the use of advanced energy-saving and emission-reduction technologies such as the Miller cycle, and can be adjusted accordingly according to the intensity of the Miller cycle to obtain a more accurate maximum crankcase gas volume.

[0037] In the embodiment of the present invention, for a single-stage supercharging system, the supercharging system type coefficient of the diesel engine is The value is 1.

[0038] In the embodiment of the present invention, for a two-stage supercharging system, the supercharging system type coefficient of the diesel engine is The value is 1.2857.

[0039] The maximum crankcase blowby volume of diesel engines is optimized.

[0040] For example, the relevant structure and performance parameters of the locomotive diesel engine and the maximum crankcase blowby volume are shown in the following table:

[0041] S40, conduct simulation and analysis, and then carry out component design, strength and safety assessment.

[0042] Combined with the existing measured data of the crankcase blowby volume of the new locomotive diesel engine, the curve of its change with the cumulative running time of the diesel engine is fitted as follows: Figure 2 shown.

[0043] The crankcase blowby volume calculated by the curve after the diesel engine has been running for 25,000 hours is 3,520 L / min, which is basically consistent with the maximum crankcase blowby volume obtained by the optimization design method of the present invention.

[0044] The maximum crankcase blowby volume of the optimized design is basically consistent with the crankcase blowby volume data results obtained through actual measurement, and can be used to more accurately design and select the oil-gas separator.

[0045] The present invention accurately designs the diesel engine crankcase blowby volume; optimizes the oil-gas separator design or selection; optimizes the oil-gas separator filtering efficiency; optimizes the diesel engine emission performance; reduces the diesel engine oil consumption rate; and improves the diesel engine's economic and social benefits.

[0046] It should be understood that, although described in a certain order, these steps are not necessarily performed in sequence in the above order. Unless there is clear explanation in this article, the execution of these steps does not have strict order restriction, and these steps can be performed in other orders. Moreover, a part of the steps of the present embodiment may include a plurality of steps or a plurality of stages, and these steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a part of the steps or stages in other steps or other steps.

[0047] It should be understood that, as used herein, the singular form "a" or "an" is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations of one or more of the items listed in association. The serial numbers of the embodiments disclosed in the above embodiments of the present invention are for description only and do not represent the advantages and disadvantages of the embodiments.

[0048] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. An optimization design method for a high-power diesel engine oil-gas separator, characterized in that: The method includes: Determine the demand analysis of oil and gas separator; Determine the separation technology and the structure of the oil-gas separator based on the demand analysis; Determine the detailed parameters of the oil-gas separator, where the maximum crankcase blowby volume of the oil-gas separator must meet the following formula: ， In the formula, —Maximum crankcase blowby volume (l / min); —Rated speed of diesel engine (r / min); —Scavenging air pressure of diesel engine cylinder (bar.abs); —Scavenging air temperature of diesel engine cylinder (K); —Displacement of diesel engine (L); —Impulse coefficient of diesel engine; —Type coefficient of turbocharging system of diesel engine; Conduct simulations and analyses leading to component design, strength and safety assessments.

2. The optimization design method of a high-power diesel engine oil-gas separator as claimed in claim 1, characterized in that: The demand analysis for determining the oil-gas separator includes: Determine the oil and gas flow rate that the separator needs to handle; Analyze the specific properties of oil and gas; Determine separation efficiency requirements; Consider the operating pressure and temperature range.

3. The optimization design method of a high-power diesel engine oil-gas separator as claimed in claim 1, characterized in that: The separation technology and the structure of the oil-gas separator are determined based on the demand analysis.

4. The optimization design method for a high-power diesel engine oil-gas separator as claimed in claim 3, characterized in that: Separation techniques include gravity separation, centrifugation or filtration.

5. The optimization design method for a high-power diesel engine oil-gas separator as claimed in claim 3, characterized in that: The structures of oil-gas separators include vertical, horizontal or spherical.

6. The optimization design method for a high-power diesel engine oil-gas separator according to claim 1, characterized in that: The rated speed of a diesel engine ranges from 1000r / min to 2000r / min.

7. The optimization design method for a high-power diesel engine oil-gas separator as claimed in claim 6, characterized in that: Impulse coefficient of diesel engine The minimum value range is 0.

55.

8. The optimization design method for a high-power diesel engine oil-gas separator as claimed in claim 7, characterized in that: In a single-stage supercharging system, the supercharging system type coefficient of the diesel engine The value is 1.

9. The optimization design method for a high-power diesel engine oil-gas separator as claimed in claim 8, characterized in that: In a two-stage supercharging system, the supercharging system type coefficient of the diesel engine The value is 1.2857.

10. The optimization design method for a high-power diesel engine oil-gas separator according to claim 1, characterized in that: The diesel engine calibration tool says that the maximum range of the cylinder scavenging pressure can reach 8 bar.abs, which covers the ultra-high boost pressure including the two-stage boost system.

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