直喷汽油机直接喷油起动瞬变过程燃烧机理和排放控制研究
发布时间：2018-12-18 03:14
【摘要】：随着我国经济的高速发展,机动车总量也在飞速增长,随之带来的能源紧缺与环境污染问题日益突出。国家最新出台了一系列的环保法规,尤其是针对机动车发动机领域所颁布的排放法规和燃油油耗法规也越来越严格。城市道路拥堵,交通状况的恶化,尤其是机动车在市区内等待红灯的情况,会导致机动车长时间处于怠速工况,机动车在怠速工况下不但消耗燃油还会增加尾气的有害污染物排放。所以怠速工况起动停止这一有效的节能减排的技术应运而生,借助缸内直喷汽油机能够高柔性地对缸内的喷油及点火参数进行控制的特点,使发动机无需借助起动电机的辅助即可起动,直接起动模式能够有效摒弃传统起动方式的一些固有缺陷,可以在很大程度上减少城市拥堵及等待红灯时的怠速工况,从而达成降低油品消耗,减少有害污染物排放的目的。还因起动停止技术的安全性高、起动反应迅速、改造费用低并且在震动噪声等舒适性指标上也能给机动车带来改善,所以正得到人们的高度关注并有望普及推广。本文基于缸内直喷汽油机搭设建立了直接起动过程瞬态测控平台,针对缸内直喷汽油机直接喷油起动这一特殊瞬变过程,以试验和模拟仿真这两种方法探究了正转直接起动过程和反转直接起动过程之中发动机的控制参数(包括喷油时刻、点火时刻、过量空气系数等)、发动机的状态参数(包括喷油压力、冷却液温度、活塞初始位置等)和停机策略(停机过程中节气门开度、停机转速)对直接起动前两循环的转动特性、燃烧特性及排放性能的影响。研究缸内混合气形成、燃烧过程、有害排放物生成和气缸运动历程及其与传统起动工况的化学动力学和运动学的区别;分析不同热氛围、化学氛围和喷射能量等燃烧初始边界条件对缸内燃烧过程和有害物形成历程的影响规律,丰富点燃式内燃机瞬变工况燃烧理论;界定出简单、可靠的首循环稳定点燃所需的边界条件及后续起动过程能稳定进行的气缸运动特征;确定影响起动瞬变过程燃烧和排放的关键因素及其优化控制策略。基于主动控制瞬变燃烧边界条件的策略提高发动机起动性能、降低排放污染物。为实现缸内直喷汽油机频繁、快速、高效和低排放的起动过程提供理论依据。本项目分主要研究结论:1.直接起动模式缸内混合气形成、燃烧过程、有害排放物排放及发动机转动特性与控制参数及起动条件密切相关;适当的两次喷射策略能加快缸内燃烧放热速度、发动机转速提高。2.活塞初始位置是影响直接起动模式能否成功起动的重要因素。正转直接起动及反转直接起动模式能够成功起动,所对应的发动机缸内活塞初始位置既有一定的范围的重和,又存在一定范围的差异;冷却液温度过高或过低直接起动模式实现的活塞初始位置范围均有所减小,70℃冷却液温度时活塞初始位置范围最大;提高喷射压力有利于扩大直接起动模式实现的活塞初始位置范围,但影响程度有限;将膨胀缸的活塞控制在90°CA-125°CA能在较宽冷却液温度和喷射压力范围内使直接起动模式实现。3.停机过程增大节气门开度更易于降低气缸内的残余废气量,直接起动模式首循环着火及起动成功概率大幅度提高。同时,增大节气门开度还可使活塞停止在气缸中间位置的概率显著升高;起动机辅助起动模式首循环的着火界限较直接起动模式显著变宽,且其着火行为也更为复杂,会有“自燃”情况出现。通过本项目研究,一方面丰富了点燃式发动机瞬变工况燃烧理论;另一方面为缸内直喷汽油机直接起动模式推广和应用提供了一定的理论基础和数据支撑。
[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 掳 CA-125 掳 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，
本文编号：2385233
[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 掳 CA-125 掳 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，
本文编号：2385233
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