Experimental study on the performance of ultra high pressure common rail system

超高压共轨系统性能试验研究

College of Power Engineering, Naval University of Engineering, Wuhan 430033, China

Received: 22 December 2020

Abstract

In order to overcome the difficulties of high pressure source design and parts integration in the injector, realizing the ultra high pressure injection and controllable fuel injection rate, an ultra high pressure common rail system based on domestic basic materials and manufacturing technology level was proposed and designed. The working principle of this system was first introduced; the performance test bench of ultra high pressure common rail system was built. Then, the influence of pressure-amplifier device structure parameters on the pressurization pressure peak was analyzed quantitatively, and on the basis of selecting the most appropriate combination of parameters, the pressure and fuel injection rate control characteristics were conducted. The results show that ultra high pressure common rail system can magnify fuel pressure to ultra high pressure state (more than 200 MPa) and by changing the control signal timing of pressure-amplifier device and injector solenoid valve, the flexible and controllable fuel injection rate can be achieved. Under the condition of the same pressurization ratio, the peak value of pressurization pressure increases gradually, and with the increase of pressurization ratio, the increasing trend of the pressurization pressure peak value is nonlinear. At the same time, under the same condition of spring preload, the greater of the spring stiffness, the higher of the rail base pressure can bear, that means the pressure-amplifier device can achieve pressurization at a higher base pressure. But if the spring stiffness is too large, the solenoid valve of pressure-amplifier device will not be opened due to insufficient electromagnetic force, so the specific selection should be considered in a compromise.

摘要

为克服高压源设计和喷油器内零部件难于集成的困难，实现超高压力喷射和可控喷油速率喷射，立足国内基础材料及加工制造工艺水平，提出并设计了超高压共轨系统。介绍了系统的工作原理，搭建了超高压共轨系统性能测试台架，定量分析了增压装置结构参数对增压峰值的影响，选取最佳参数组合开展了压力特性和喷油速率控制特性试验。结果表明：超高压共轨系统能够将燃油压力放大至超高压状态(大于200 MPa)，并且通过改变增压装置和喷油器各自电磁阀的控制信号时序，能够实现灵活可控的喷油速率。在相同的增压比条件下，随着进油节流孔直径的增加，增压峰值逐渐增大，并且随着增压比的增大，增压峰值呈现非线性的增加趋势。同时，在相同弹簧预紧力的情况下，弹簧刚度越大，可承受的轨腔基压越高，这就意味着增压装置可在更高的基压下实现增压。但弹簧刚度过大会导致增压装置电磁阀电磁力不足无法打开，具体选择时应当折中考虑。