【摘要】：隨著我國經(jīng)濟的高速發(fā)展,機動車總量也在飛速增長,隨之帶來的能源緊缺與環(huán)境污染問題日益突出。國家最新出臺了一系列的環(huán)保法規(guī),尤其是針對機動車發(fā)動機領(lǐng)域所頒布的排放法規(guī)和燃油油耗法規(guī)也越來越嚴格。城市道路擁堵,交通狀況的惡化,尤其是機動車在市區(qū)內(nèi)等待紅燈的情況,會導(dǎo)致機動車長時間處于怠速工況,機動車在怠速工況下不但消耗燃油還會增加尾氣的有害污染物排放。所以怠速工況起動停止這一有效的節(jié)能減排的技術(shù)應(yīng)運而生,借助缸內(nèi)直噴汽油機能夠高柔性地對缸內(nèi)的噴油及點火參數(shù)進行控制的特點,使發(fā)動機無需借助起動電機的輔助即可起動,直接起動模式能夠有效摒棄傳統(tǒng)起動方式的一些固有缺陷,可以在很大程度上減少城市擁堵及等待紅燈時的怠速工況,從而達成降低油品消耗,減少有害污染物排放的目的。還因起動停止技術(shù)的安全性高、起動反應(yīng)迅速、改造費用低并且在震動噪聲等舒適性指標上也能給機動車帶來改善,所以正得到人們的高度關(guān)注并有望普及推廣。本文基于缸內(nèi)直噴汽油機搭設(shè)建立了直接起動過程瞬態(tài)測控平臺,針對缸內(nèi)直噴汽油機直接噴油起動這一特殊瞬變過程,以試驗和模擬仿真這兩種方法探究了正轉(zhuǎn)直接起動過程和反轉(zhuǎn)直接起動過程之中發(fā)動機的控制參數(shù)(包括噴油時刻、點火時刻、過量空氣系數(shù)等)、發(fā)動機的狀態(tài)參數(shù)(包括噴油壓力、冷卻液溫度、活塞初始位置等)和停機策略(停機過程中節(jié)氣門開度、停機轉(zhuǎn)速)對直接起動前兩循環(huán)的轉(zhuǎn)動特性、燃燒特性及排放性能的影響。研究缸內(nèi)混合氣形成、燃燒過程、有害排放物生成和氣缸運動歷程及其與傳統(tǒng)起動工況的化學(xué)動力學(xué)和運動學(xué)的區(qū)別;分析不同熱氛圍、化學(xué)氛圍和噴射能量等燃燒初始邊界條件對缸內(nèi)燃燒過程和有害物形成歷程的影響規(guī)律,豐富點燃式內(nèi)燃機瞬變工況燃燒理論;界定出簡單、可靠的首循環(huán)穩(wěn)定點燃所需的邊界條件及后續(xù)起動過程能穩(wěn)定進行的氣缸運動特征;確定影響起動瞬變過程燃燒和排放的關(guān)鍵因素及其優(yōu)化控制策略�；谥鲃涌刂扑沧�?nèi)紵吔鐥l件的策略提高發(fā)動機起動性能、降低排放污染物。為實現(xiàn)缸內(nèi)直噴汽油機頻繁、快速、高效和低排放的起動過程提供理論依據(jù)。本項目分主要研究結(jié)論:1.直接起動模式缸內(nèi)混合氣形成、燃燒過程、有害排放物排放及發(fā)動機轉(zhuǎn)動特性與控制參數(shù)及起動條件密切相關(guān);適當?shù)膬纱螄娚洳呗阅芗涌旄變?nèi)燃燒放熱速度、發(fā)動機轉(zhuǎn)速提高。2.活塞初始位置是影響直接起動模式能否成功起動的重要因素。正轉(zhuǎn)直接起動及反轉(zhuǎn)直接起動模式能夠成功起動,所對應(yīng)的發(fā)動機缸內(nèi)活塞初始位置既有一定的范圍的重和,又存在一定范圍的差異;冷卻液溫度過高或過低直接起動模式實現(xiàn)的活塞初始位置范圍均有所減小,70℃冷卻液溫度時活塞初始位置范圍最大;提高噴射壓力有利于擴大直接起動模式實現(xiàn)的活塞初始位置范圍,但影響程度有限;將膨脹缸的活塞控制在90°CA-125°CA能在較寬冷卻液溫度和噴射壓力范圍內(nèi)使直接起動模式實現(xiàn)。3.停機過程增大節(jié)氣門開度更易于降低氣缸內(nèi)的殘余廢氣量,直接起動模式首循環(huán)著火及起動成功概率大幅度提高。同時,增大節(jié)氣門開度還可使活塞停止在氣缸中間位置的概率顯著升高;起動機輔助起動模式首循環(huán)的著火界限較直接起動模式顯著變寬,且其著火行為也更為復(fù)雜,會有“自燃”情況出現(xiàn)。通過本項目研究,一方面豐富了點燃式發(fā)動機瞬變工況燃燒理論;另一方面為缸內(nèi)直噴汽油機直接起動模式推廣和應(yīng)用提供了一定的理論基礎(chǔ)和數(shù)據(jù)支撐。
[Abstract]:With the high-speed development of our country's economy, the total volume of the motor vehicle is also increasing rapidly, and the energy shortage and environmental pollution brought by it are becoming more and more serious. The state-of-the-art regulations on environmental protection, in particular those issued in the field of motor-driven engines, are becoming more and more stringent. The traffic jam and the deterioration of the traffic situation, in particular in the case of a motor vehicle waiting for a red light in the urban area, can lead the motor vehicle to be at an idle speed for a long time, and the motor vehicle not only consumes the fuel oil under the idle speed working condition, but also increases the harmful pollutant discharge of the tail gas. Therefore, the technology of starting and stopping the active energy-saving and emission-reduction in the idle-speed working condition has come into being, and the injection and ignition parameters of the in-cylinder can be controlled flexibly with the aid of the in-cylinder direct-injection gasoline engine, so that the engine can be started without the aid of the starting motor, The direct starting mode can effectively abandon some inherent defects of the traditional starting mode, and can greatly reduce the urban congestion and the idle speed working condition when the red light is waiting, so as to achieve the purpose of reducing oil consumption and reducing the emission of harmful pollutants. but also because of the high safety of the starting and stopping technology, the starting reaction is rapid, the transformation cost is low, and the comfort index such as the vibration noise can also bring the motor vehicle to improve, so that the high attention of people is being obtained and the popularization is expected to be popularized. in this paper, a transient measurement and control platform for direct start-up process is set up based on in-cylinder direct injection gasoline engine, and a special transient process is started for direct injection of a direct-injection gasoline engine in an in-cylinder, The control parameters of the engine (including injection timing, ignition timing, excess air coefficient, etc.) of the engine and the state parameters of the engine (including the injection pressure and the coolant temperature) are investigated by both the test and the simulation. The effect of the initial position of the piston, etc.) and the shutdown strategy (throttle opening and shutdown speed during the shutdown) on the rotational characteristics, combustion characteristics and emission performance of the two cycles immediately prior to direct start-up. The paper studies the formation of mixed gas in in-cylinder, the combustion process, the generation of harmful emissions and the movement of the cylinder and the difference between the chemical dynamics and the kinematics of the traditional starting working conditions, and analyzes the different thermal atmosphere. The influence of the initial boundary conditions such as the chemical atmosphere and the injection energy on the in-cylinder combustion process and the formation of the harmful substances is regular, the combustion theory of the transient working condition of the ignition type internal combustion engine is enriched, The boundary conditions required for stable ignition of the first cycle and the characteristics of the cylinder motion which can be stably performed in the subsequent start-up process are determined; the key factors affecting the combustion and emission of the starting transient process and the optimization control strategy are determined. Based on the strategy of active control of transient combustion boundary conditions, the starting performance of the engine is improved and the emission of pollutants is reduced. so as to provide a theoretical basis for realizing the frequent, rapid, high-efficiency and low-emission starting process of the in-cylinder direct-injection gasoline engine. The main research conclusions of this project are as follows: 1. in that direct-start mode, the in-cylinder mixture formation, the combustion process, the harmful emission discharge and the engine rotation characteristic are closely related to the control parameters and the start condition; the appropriate two injection strategies can accelerate the in-cylinder combustion heat release speed, and the engine speed is improved. The initial position of the piston is an important factor affecting the success of the direct starting mode. the direct starting mode and the reverse direct starting mode can be started successfully, and the initial position of the corresponding engine in-cylinder piston has a certain range of weight and a certain range of difference; The initial position range of the piston is reduced when the temperature of the cooling liquid is too high or the direct starting mode is too low, and the initial position range of the piston is the maximum when the temperature of the cooling liquid at 70 DEG C is 70 DEG C; the increase of the injection pressure is beneficial to the expansion of the initial position range of the piston realized by the direct starting mode, but the influence degree is limited; The control of the piston of the expansion cylinder at 90 擄 CA-125 擄 CA enables the direct start-up mode to be achieved over a wide range of coolant temperature and injection pressure. the increase of the opening degree of the throttle valve is easier to lower the residual exhaust gas amount in the air cylinder, and the initial cycle of the direct start mode and the success probability of the starting success are greatly improved. At the same time, the increase of the opening degree of the throttle can also cause the piston to stop at the middle of the cylinder, and the probability of the piston to stop at the middle of the cylinder is increased significantly; the ignition limit of the initial cycle of the auxiliary starting mode of the starter is wider than the direct starting mode, and the ignition behavior of the starter is more complex, and the 鈥渁utoignition鈥，

本文編號：2385233