| High-power density diesel engine is widely used by army equipment power due to its high speed,high combustion pressure and high compactness,and the high-pressure common rail fuel supply system,which is one of its core support technologies,needs to complete accurate injection timing and injection duration under the conditions of high speed,high cycle injection volume and short injection time,which puts forward higher requirements on the injection performance of high-pressure common rail system.In order to further improve the injection performance of the common rail system,this paper carries out research on the influence of the fuel supply process and injection process on the injection characteristics for the high speed and high power diesel engine common rail system,based on which the integrated matching analysis between the two is completed.Firstly,according to the basic working principle of the common rail system and the research needs,we made reasonable assumptions on the system model,based on the mathematical model of the common rail system,we established the simulation model of the common rail system in AMESim simulation platform,and verified the simulation calculation results with the bench test data,and found that the injection pressure curve of the simulation model is basically consistent with the change trend of the test results,and the maximum relative error is The maximum relative error is 5%,which is within the allowed range of engineering(≤10%),and the accuracy of the simulation model is verified.Secondly,according to the working process of high pressure common rail system,the evaluation indexes of injection characteristics and rail pressure fluctuation are defined in detail,and the opening delay,opening time,closing delay,closing time,injection duration,injection volume and injection pressure of injector are taken as the evaluation indexes to characterize the injection characteristics;the average fluctuation amount and peak fluctuation of rail pressure in the pressure building stage and pressure stabilization stage of common rail pipe are taken as the evaluation indexes to characterize the rail pressure fluctuation.The average and peak fluctuations of rail pressure in the pressure building and pressure stabilization phases of the common rail tube are used as evaluation indexes to characterize rail pressure fluctuations.The high-pressure fuel pump and common rail tube are regarded as a subsystem of the high-pressure common rail system,defined as the high-pressure fuel supply module,and the influence law of the structural parameters of the high-pressure fuel supply module on the fuel injection characteristics and rail pressure fluctuation is studied.The range of change is less than 4%,and the range of change of injection pressure is 10%;while the structural parameters of the high-pressure oil supply module have obvious influence on the fluctuation of rail pressure.Combined with the relevant literature,the influence of parameters such as plunger diameter,plunger stroke and common rail tube length on the injection characteristics and rail pressure fluctuation was compared and analyzed,which is consistent with the trend of the injection characteristics and rail pressure fluctuation derived from this paper,and verified the feasibility of the research results.In order to study the influence weight of each parameter on the rail pressure fluctuation characteristics,the key structural parameters of the high-pressure common rail module were analyzed in an orthogonal test,and the two parameters that have the greatest influence on the rail pressure fluctuation are the common rail tube inner diameter and common rail tube length,which are consistent with the results obtained from other literature.After optimization,the injection characteristics and peak rail pressure fluctuation of the injector are basically unchanged,while the average rail pressure fluctuation in the build-up phase of the common rail tube is reduced by 49.6%,the average rail pressure fluctuation in the stabilization phase when only oil is supplied without injection is reduced by 36.3%,and the average rail pressure fluctuation in the stabilization phase when normal oil is injected is reduced by 42.5%,and the degree of rail pressure fluctuation is significantly reduced to ensure The level of rail pressure fluctuation is significantly reduced,ensuring that the oil injection process can be carried out more smoothly and precisely.Then,for the above-mentioned evaluation index of the injection characteristics,the influence law of the injector structure parameters on the injection characteristics was studied,and the influence law of the parameters such as the maximum lift of the control valve,the diameter of the inlet hole and the diameter of the spray hole on the injection characteristics was compared and analyzed in conjunction with the relevant literature,which is consistent with the trend of change of the injection characteristics derived in this paper,and verifies the feasibility of the research results.On this basis to shorten the injector response time as the goal,the orthogonal experimental analysis of the key structural parameters of the injector was conducted,and the comprehensive formula scoring method was used to score the five response times of the injector,and the influence weight of each parameter on the response time score was obtained,and finally the optimization scheme of the injector response characteristics was obtained,and on the basis of not affecting the injector injection volume and injection pressure,the optimized injector opening delay was shortened by 5.36%,the opening time was shortened by 12.4%,the closing time was shortened by 7.12%,the injection duration was shortened by 1.73%,while the closing delay was increased by 9%,and the overall response characteristics of the injector were improved by 5.86%,ensuring that the injector can complete the injection timing and injection duration more accurately.Finally,the fuel supply subsystem and fuel injection subsystem of the common rail system are integrated and matched to reduce the rail pressure fluctuation,and the fuel supply volume and injection volume,fuel supply frequency and injection frequency of the common rail system are matched and analyzed,the results show that:with the increase of fuel supply volume,the rail pressure fluctuation decreases and then increases,and the rail pressure fluctuation is the smallest when the fuel supply volume is 6000 mm~3;with the increase of fuel injection volume,the rail pressure fluctuation With the increase of fuel supply frequency,the fluctuation of rail pressure decreases and then increases,and the fluctuation of rail pressure is the smallest when the fuel supply frequency is 9 times/cycle,that is,the fluctuation of rail pressure is the smallest under the ideal situation of"fuel consumption in each injection process is accompanied by fuel replenishment in one fuel supply process";with the increase of fuel injection frequency,the fluctuation of rail pressure gradually decreases.With the increase of injection frequency,the fluctuation of rail pressure decreases.By studying the influence law of each working parameter on rail pressure fluctuation,it provides a reference for the selection of working parameters of fuel supply subsystem and fuel injection subsystem.A comparative analysis of the matching laws of injection volume,injection frequency and oil supply frequency in combination with related literature is consistent with the trend of rail pressure fluctuation derived from this paper,which verifies the feasibility of the research results. |
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