To study the fuel saving algorithm for assisted driving of high-speed tractors,taking a cer-tain tractor as the research object,based on the analysis of driving behavior of excellent drivers,a predic-tive cruise control strategy for the tractor in actual road spectra was designed.In addition,the vehicle simulation software Cruise and strategy modeling software Simulink were used for joint simulation.Results show that compared with cruise control,the fuel consumption is reduced by 11.57%per 100 kilometers under the predictive cruise control strategy,and the fuel saving rate during actual vehicle testing is 6.8%.
The three-dimensional simulation model of large deformation of fluororubber seal ring was established by finite element method to study the lube oil pump rectangular seal in the bolt assembly process and different temperature contact pressure,filling rate and compression rate on the impact of seal-ing performance.The results show that the large deformation analysis of the seal can get accurate contact pressure in the sealing area.And under the low temperature condition of-40℃,the lubricant pump cold shrinkage to the middle increases the extrusion of the contact area to make the contact pressure increase.As the temperature rises to 120℃,the lubricant pump thermal expansion reduces the contact pressure,the maximum contact pressure under each working condition is greater than the oil internal pressure of 1.98 MPa.As the temperature increases,the filling rate of the seal gradually increases,and the filling rate of the seal at different temperatures is less than 85%,while the compression rate of the seal de-creases,and the compression rate at different temperatures is in the range of 13%to 36%.The filling rate and compression rate meet the design requirements.
An efficient oil gas separation structure integrated on the cylinder head cover for a Na-tional VI diesel engine was designed.The adsorption cotton was equipped in the fine separation unit and worked well for small oil fractional particles.The basic structural parameters of the product were deter-mined through computational fluid dynamics(CFD)gas-liquid two-phase flow analysis method,and the separation efficiency of oil droplets with different particle sizes and gas flow pressure loss were tested us-ing the German Topas oil-gas separation equipment.By adjusting the diameter of orifice plate in front of the filter cotton,the effect of different airflow impact velocities on the adsorption effect of the filter cotton was studied,and the optimal diameter of the accelerating pore was determined.The results show that af-ter adding adsorption type filter cotton,the separation efficiency of small oil droplets within 0.5μm can be improved by about 25 percentage points.The final designed sample can be verified to be qualified through engine bench testing,and the oil mass flow rate at the outlet is about 0.48 g/h.
For natural gas engines,exhaust gas recirculation(EGR)can effectively suppress the generation of nitrogen oxides(NOx)while reducing the combustion temperature in the engine cylinder.However,differences in EGR rates among cylinders can lead to differences in combustion,thereby in-creasing the risk of misfire and detonation.EGR rate tests on each cylinder and computational fluid dy-namics(CFD)simulation analysis of the intake pipeline were conducted based on a China Ⅵ natural gas engine.By optimizing the structural design of the intake pipeline,the uniformity of the EGR rate was ef-fectively improved.The uniformity of EGR rate in each cylinder was≤2.5%,which meets the design re-quirements and can provide reference for the design and development of intake pipes in engines.
Taking the 6.7 L China Ⅵ diesel oil gas separator as the research object,the structural characteristics of the oil gas separator were analyzed.Based on the original oil gas separator structure,the oil gas separator was optimized and designed.Computational fluid dynamics(CFD)finite element analysis software was used for steady-state pressure and flow rate analysis,and experimental verification was conducted on the Topas oil and gas separation test bench in Germany.The results show that by opti-mizing measures such as adding filter cotton,reducing pore size,and increasing the pore number to the oil gas separator,the design goal of less than 1.0 g/h of the oil carrying mass flow rate for the crankcase ventilation system has been achieved,and its emissions have met the requirements of the national emis-sion regulations.
The test temperature field is as consistent as possible with the operating temperature field of the diesel engine exhaust manifold,which can verify the improvement effect of the diesel engine ex-haust manifold efficiently.In order to verify the optimization and improvement effect of diesel engine ex-haust manifold quickly,a device simulating the working temperature field of diesel engine exhaust mani-fold is designed and developed.The equipment adopts electromagnetic field distributed heating method and simulates the actual working conditions of the diesel engine exhaust manifold through high-temperature air cooling and low-temperature fog cooling,which helps to shorten the development cycle of the diesel engine exhaust manifold and reduce its development cost.The results show that by changing the power of the power supply,the heating rate of the heating coil can be controlled.By adjusting the magnetic field line density of the heating coil,the heating efficiency of the heating coil is changed,and the temperature field of the diesel engine exhaust manifold is effectively controlled.
The flywheel has the risk of crack failure due to the large rotational inertia force at high speed.In order to reduce the cost of project development,simulation method is needed to evaluate whether it can pass the test in the early stage of design freezing.The simulation results of traditional analysis methods often do not meet the requirements of static strength design,but can pass the test.Therefore,based on the principle that the relative stress gradient can modify the allowable stress of mate-rials,a flywheel static strength analysis method based on static safety factor is proposed.The results show that the analysis results of this method are consistent with the experimental results,avoiding the overdesign of the structure and having the effect of reducing weight and cost on the flywheel.
《柴油机设计与制造》创刊于1979年,是由上海汽车工业(集团)总公司主管,上海新动力汽车科技股份有限公司主办的集学术性、技术性、实用性于一体的科技期刊.本刊国内外公开发行,属中国内燃机专业核心期刊,在发动机行业中具有较大的影响力.《柴油机设计与制造》是《中国期刊学术期刊(光盘版)》(中国知网)全文收录期刊,是《中国核心期刊(遴选)数据库》(万方数据)、《中文科技期刊数据库》(重庆维普)及《中国期刊综合评价数据库》数据库刊源期刊.
High temperature resistant vermicular graphite cast irons with different vanadium con-tents were prepared,and the chemical composition,tensile strength,graphite morphology,and metallo-graphic structure of the samples were tested through tests such as room temperature stretching,high tem-perature stretching,and metallographic examination.The results show that after adding vanadium me-dium,the graphite distribution in the matrix is more uniform.The tensile properties of the material at room temperature show no significant change with the increase of vanadium content.The high-temperature tensile performance of the material continuously improves with the increase of vanadium con-tent,but the increase slows down by improvement.
During the development process of an 8-cylinder inline engine,there was a problem of high turbocharger vibration speed.Turbocharger simulation model was established by using Abaqus soft-ware,and the model was modified according to the measured results of turbocharger vibration.According to the simulation results,the improvement suggestions were proposed:strengthen the fixation of the whole machine and reduce the vibration of excitation source,reduce the height of the turbocharger sup-port and increase the stiffness of the support.Vibration testing was conducted on the optimized turbo-charger.The results show that the vibration speed is below the limit value,meeting the design require-ments.
Taking the direct injection engine injector as the research object,the multi-domain flow characteristics were analyzed,and the injector model was established based on its operating characteris-tics.The different injection processes were divided into ballistic region,linear region and transition re-gion for calculating the injection pulse width.Secondly,according to the modern software development process and Simulink platform,the variable structure control algorithm was established and tested.Fi-nally,the control model was calibrated according to the fuel injector flow test results.The result shows that the injection errors of low flow area and transition area are both less than 5%,and the injection error of high flow area is less than 3%.
为研究挖掘机用弹性联轴器对柴油发动机曲轴扭振的影响,搭建发动机本体曲轴一维仿真模型,结合台架试验对影响曲轴扭振的重要因素进行标定.基于台架标定参数搭建整车计算模型,研究动力总成发动机后端弹性联轴器解耦对曲轴扭振的影响.结果表明:皮带轮系刚度和阻尼对发动机曲轴的扭振有一定抑制作用,不带皮带轮系的建模结果更保守;匹配整车用弹性联轴器主激励阶次的扭振幅值较台架和整车解耦状态下略高,同平台可采用解耦方式建模;当弹性联轴器扭转刚度较小或接近减振器扭转刚度时会产生零频响应,需要根据曲轴应力和疲劳结果进行综合判断,台架扭振测试结果不能完全反映整车实际的扭振水平.
针对大功率发动机为提升功率、扭矩,以及排放升级所带来的高排温、高排气侧向力的问题,探究气门导管材料升级方案,并分析气门导管材料与缸盖结构的匹配,以降低排气门与气门导管摩擦副的磨损量.将提出的3种气门导管材料升级方案分别应用在Ⅰ型和Ⅱ型结构缸盖上进行发动机耐久验证.结果表明:300℃气门导管、Ⅱ型结构缸盖匹配高硬度材料C时,气门导管磨损量可减小33％;400℃及以上气门导管、Ⅰ型结构缸盖匹配高导热材料B时,气门导管磨损量可减小49％.
2022年11月发布的欧洲第七阶段排放法规(以下简称"欧七排放法规")草案对汽车尾气排放中固体悬浮微粒数量(PN)的检测方法和排放限值都做了修改,这对于满足中国第六阶段排放法规(以下简称"国六排放法规")的汽车带来了新的挑战.以某款重型柴油机为例,对其进行全流程发动机台架试验,在世界统一瞬态循环(WHTC)工况下,对比国六排放法规与欧七排放法规对于PN限值的差异.通过对比PN排放,明确催化器后不同粒径颗粒物(PM)的来源,并通过改变尿素喷射频率和优化选择性催化还原(SCR)混合器,控制PM的生成,从而降低PN排放,以满足欧七排放法规.
用CONVERGE软件对预燃室燃烧系统模型进行网格划分,设置关键参数以研究预燃室喷孔数对湍流比、湍动能、空燃比、缸内混合气流速的影响.结果表明:进气行程结束前,预燃室喷孔数对湍流比无影响;气门关闭时,预燃室喷孔数为偶数对湍流比无影响,奇数则对湍流比影响较大;预燃室喷孔数对湍动能影响较小;预燃室喷孔数对主燃室空燃比影响不大;预燃室喷孔数减少,可以提升缸内混合气流速.
针对目前车用发动机试验室启动电源装置存在的质量缺陷,以超级电容器为基础,设计一种车用发动机试验室启动电源装置.经实测,该装置的2项关键评测指标,即静态电压输出交流谐波成分、动态启动压降均优于现有的晶闸管启动电源装置与蓄电池启动电源装置,满足车用发动机试验室实际使用需求.
《现代铸铁》杂志创刊于1981年,由一汽铸造有限公司主管,无锡一汽铸造有限公司与中国机械工程学会联合主办,双月刊(双月25日出版),国内外公开发行,邮发代号:28-178,国内统一连续出版物号:CN 32-1112/TG,国际标准连续出版物号:ISSN 1003-8345,国际刊名代码:CODEN XZHUEJ.
注塑成型复合材料的属性为各向异性且受注塑工艺影响,采用复合材料注塑成型的零部件各区域材料分布不均匀,导致其频响振动分析方法与常规采用各向同性材料制造的零部件的分析方法存在很大差异.基于Digimat软件逆向获得了用于制造油底壳的玻纤增强聚酰胺66(35％GF/PA66)材料属性,通过供方提供的模流分析结果,提取了油底壳纤维取向张量分布,通过多尺度联合仿真方法对油底壳进行了模态仿真分析及测试.结果表明,前5阶模态仿真值与测试值的最大相对误差在8％以内,满足工程应用精度需求,验证了仿真方法的有效性.在模态仿真基础上进行频响分析及试验验证,试验结果与仿真结果的趋势一致,所得结果可为复合材料零部件振动分析提供参考.
由于柴油机运行工况条件复杂,中、低负荷工况下排气温度较低,无法满足柴油机颗粒捕捉器(DPF)主动再生的温度要求,因此需要对再生温度控制进行系统研究.研究了稳态工况下通过调节柴油机后喷油量、节气门开度对DPF内部温度控制的影响,以实现DPF入口温度满足主动再生的要求;同时研究分析降怠速(DTI)工况下不同炭载量载体再生时,DPF内部温度变化情况,以提高DPF主动再生过程中的安全性.结果表明:调节柴油机后喷油量、节气门开度,能够有效控制DPF内部温度,DTI工况下炭载量是影响DPF内部最高温度的主要因素.
废气再循环(EGR)系统可以有效地降低燃气发动机热负荷、爆燃风险及氮氧化物(NOx)排放量,具有提高发动机经济性的作用.单向阀作为EGR系统的一个重要部件,可以起到提升发动机低转速段扭矩和降低发动机气耗的作用.对比EGR系统有无单向阀时对燃气发动机性能的影响,验证A、B两款单向阀对于提升发动机性能所起的作用,以及在燃气发动机复杂工况条件下自身的可靠性.使得结论可为燃气发动机匹配合适的EGR单向阀提供参考.
