【作者】 隗海林；

【导师】 王云鹏；

【作者基本信息】 吉林大学 ， 载运工具运用工程， 2007， 博士

【摘要】 随着汽车保有量的不断增加,汽车带给人们生活便利的同时,也给全社会带来了能源短缺、大气污染等严重问题,发展代用燃料汽车已经成为节能与环保的有效途径之一。LPG作为燃料其许多特性与汽油相近,已发展成为世界范围内应用最广的汽车代用燃料。在我国由于受加气站数量和布局的影响,目前以使用LPG/汽油两用燃料汽车为主,但两用燃料汽车普遍存在由汽油向LPG燃料转换过程中转速、转矩波动大,短时间排放过高的难题。针对两用燃料发动机燃料转换的问题,本文以捷达车ATK型发动机为研究对象,建立发动机台架试验台,研究了发动机稳态工况不同水温、不同转速、不同油门开度下燃料转换过程中的缸内燃烧压力、转速、转矩、排放的变化规律,以及加速、减速过程中进行燃料转换的缸内燃烧压力、转速、转矩、排放的变化规律。通过对试验数据进行分析得出:转速、转矩的波动和排放的短时间恶化都与燃料转换过程出现断火或燃烧不良的循环次数有直接关系,断火或燃烧不良的循环次数越多,燃料转换过程的波动及排放短时间恶化越显著。对试验结果的分析表明:燃料转换过程中汽油停止喷射时,LPG燃料的供给不及时,导致混合气过稀,使得燃烧不正常。本文提出汽油喷射延迟的方法,以解决燃料转换过程中的问题。即燃料转换时汽油与LPG同时喷射一定时间,保证顺利完成燃料转换的过渡。由于不同工况下汽油喷射延迟的时间规律性不强,本文使用模糊自适应神经网络ANFIS对试验结果进行分析处理,得到了发动机在燃料转换过程中汽油喷射延时的控制规律。利用得到的控制规律进行了燃料转换的试验验证,试验结果表明,本文所研究的控制方法可以较好地控制LPG/汽油两用燃料发动机在燃料转换过程中的转速、转矩波动,降低转换过程中的废气排放。更多还原

【Abstract】 Along with the fast development of automobile industrial and the continual increase of automobile retain quantity, which bring importance revolution to society, at the same time, also bring a lot of severity problem, such as energy crisis, atmosphere pollution. Seeking automobile substitute clean fuel, reducing petrol dependence extent and the emission have been the study hotspot for the automobile field.In all the substitute fuel using in the automobile, LPG becomes the most extensive, for which has advantage of economy, low emission, the convenience of store and transport, and the perfect extent of automobile technology. Due to the influence of our country gas station number and the position, most LPG automobile is using the flexible fuel at present. When LPG fuel is used, decompression adjustor decompress vaporize gas bottle from liquid state to gaseity. When using LPG, decompression booster decompress vaporize fuel in gas bottle from liquid state to gas state, this process need to absorb vast heat. If there isn’t enough heat, the temperature of LPG will descend rapidly, what’s worse, sometimes LPG can be concreted, the redactor can be congealed, and so the usual gas supply is failed. At work, LPG/petrol flexible fuel automobile use engine cooling fluid which circulating through redactor to provide heat for LPG gasifying. Therefore, LPG/Petrol dual-fuel engine use petrol to start usually, then shift gas to LPG, when certain conditions are satisfied after work for a while. But the shift process from gas to LPG of the LPG/petrol dual-fuel engine has two problems: 1.The great fluctuation of engine rotational speed and torque influencing traveling safety and sitting comfort; 2. The emission is exorbitant in a short time, the emission of fuel shift process is equal to engine to start anew. From the points of view: satisfy the new let statute, reduce vehicle let, and strengthen traveling safety, it’s important to solve those problems.This paper regards LPG/gas dual-fuel engine which refitted from the type of ATK JETTA engine as the research object, constructs the experiment flat roof for dual-fuel engine fuel shift in the base of analyzing the physical and chemic characteristic and the fuel electric-controlled principle, and then realizes the shift process during stable and transient operations. By analyzing the data, the way of fuel injection delay be educed to solve the problems which appear in the shift process. The adapt nerve faintness illation system (ANFIS) is used to constitute model for fuel injection delay in different operation, educe the control rule of shift process from gas to LPG of the LPG/petrol dual-fuel engine. The apply experiment indicates the shift process becoming calmer and the emission of exhaust pollution decrease clearly.During development and application of this control system, the main tasks include:1. In accordance with Dream XXI gas injection system from OMVL, LPG/petrol flexible fuel engine is converted on JETTA gasoline fuel injection engine.2. On the basis of analyzing the influence of LPG fuel on the combustion, a further study is carried on the theory of gas electronic control and the switching about the fuel of the LPG/petrol flexible fuel engine.3. Design the platform for experiment on the LPG/petrol flexible fuel engine, using the PCI-9812 20MHz in-phase 4 channels simulation data acquisition card, a high-speed and credible collection of the data such as cylinder pressure, rotate speed, torque can be finished, accompanied by the collection of signals such as accelerograph opening and the exhaust gas.4. When under stable operation, it analyzes the influences of rotate speed, the fluctuation of torque and the short time deteriorism when under different rotate speed, torque and different temperature of the cooling water. And as the result indicates: the higher the temperature of the cooling water is, the smaller the fluctuation during the switching is, but the disciplinarian of the rotate speed and the torque is not clear.5. As the study on acceleration operation going on, the experiment data indicates: the short time of the fuel switching emission reaches the maximum when under acceleration, and the assignment can not be accomplished; the fuel switching is better when under deceleration.6. As the experiment shows: rotate speed, the fluctuation of torque and the short time deteriorism of the emission all have direct relation with the number of bad-combustion and the fire break, the bigger the number is, the worse the deteriorism is.7. In order to keep the stable operation of the switching of the fuel, here applying that the supply of the gasoline is delayed 1 hour, gasoline and LPG are ejected at the same time.8. The data of the experiment indicates: during the switching bad-combustion turn up and the fire break time isn’t uniform, and it has a bad disciplinarian, it is difficult to describe it with formulas exactly; so we establish the control model using the ANFIS, and control disciplinarian chart of the gasoline eject delay time during the switching.9. And then validate the control disciplinarian via SCM, the result indicates: the production in this paper can control the rotate speed and the fluctuation of torque in the switching of the LPG/petrol flexible fuel engine; it also can reduce the exhaust gas in this process.The main inventive tasks include:1. First deep study on the shift process from petrol to LPG of the LPG/Petrol flexible fuel Engine in our country. The result of study show: the reason that engine rotational speed and torque fluctuate and emission volume rise is lost fire and bad combustion in process of fuel shift, which indicate that the air/fuel ratio doesn’t satisfy the requirement of engine steady running.2. Establish control model with adaptive fuzzy ratiocinative neural system (ANFIS), gain a control rule map of petrol injecting delay time in process of fuel shift.3. Used the PIC16F873 SCM to carry on the experiment verification towards the control rule, the result of this paper can control goodly the shift process of the LPG/Petrol flexible fuel engine, to steady engine rotational speed and torque fluctuate and reduce emission volume.更多还原