MTU高压共轨柴油发动机电子喷射系统原理

由发动机前端的一套齿轮驱动，将燃油以全负荷压力提供给沿发动机纵向铺设的共用给油管，每个气缸盖上装一个由电磁阀控制的喷油器，由高压油管将共用油管与喷油器相连通；油轨中的燃油压力及喷油嘴开、闭的时刻决定了各缸的喷油量，这些都由电子装置控制；电子装置通过装在油轨前的压力传感器感知系统中的压力；而燃油是通过一节流阀进入高压泵的，在电子装置的控制下，通过对流量的节流实现对压力的调整；MTU高压共轨柴油发动机|MTU高压共轨柴油发动机维修技术|MTU高压共轨柴油发动机电子喷射系统原理资料|MTU高压共轨柴油发动机维修服务商喷油嘴则具有控制喷油开始、停止的功能，从而控制喷油量以及调整着火延迟期喷油量等多项功能；该喷油嘴通过一个电磁阀使针阀上方泄压，然后由燃油压力控制针阀的开启速度，当控制阀泄流后，一个附加的液压阀开始动作，使针阀快速关闭。这种辅助伺服式喷油嘴能分别调整开启、关闭的特性，动作极其精确，具有极快的反应速度，能够控制怠速期间及小的供油量。高压燃油在油轨中蓄势待发，一旦某一喷油嘴接通，燃油即通过喷油嘴进入气缸。这种高压共轨式喷射系把燃油的高压产生与喷射的定时、定量完全分开，并且结构简单，还能在发动机各种转速（从额定转速到怠速）下提供相同的喷射压力。虽然在很宽的转速范围内都能提供最高压力，但共用给油管的实际压力是由电子控制系统进行调节的，从而可根据发动机功率要求而取最佳值。

4000和 8000系列柴油机所采用的高压共轨燃油喷射系统具有喷油器结构相对简单，在电磁阀处仅有小的控制油量，喷油过程易于控制，容易实现预喷油等优点。具体表现在：高压共轨式喷射系统能够精确地改变喷油定时、喷油量及喷油压力。它可在极低的柴油机转速下也获得高的喷射压力，从而有效地改善排放指标。由于燃料雾化性能的改善，高压共轨系统的最高压力可比传统的喷油系统降低 20%左右，从而降低了高压系统的零件受力、传动机械能的消耗及燃油消耗率，提高了高压系统的使用寿命，节约了维修保养的费用，提高了经济性。

高压共轨式喷射系统可对所有影响燃烧的燃油喷射参数（如燃油喷射正时、过程、时间、压力等）单独进行调控，改善混合气的形成，使之能很好适应运行工况的各种设定。单独控制燃油喷射参数可使发动机在整个功率曲线范围内减少燃油消耗和降低废气排放，有利于生态环境的改善，有助于降低发动机的噪声和振动水平；高压泵驱动装置不再承受巨大的扭矩峰值；在惰转或较低的功率范围内，切断单个气缸或气缸组，以防止较多的碳氢化合物（白烟）的排放，这样既可以最小的费用实现电子参数控制，还为喷射过程的形成（如脉冲式喷射）提供了势能，使 MTU4000和 8000系列柴油机的整体性能提高到了一个新的高度。

4共轨式燃油喷油系统的发展趋势

共轨式燃油喷射系统涉及到执行器、传感器、计算机及控制技术，发展趋势为：研究开发压电陶瓷电磁阀，以满足柴油机电控共轨燃油喷射系统要求电磁阀具有快速响应能力、工作过程精确、重复性和可靠性好的性能要求；研制新型智能型传感器和采用先进的控制模式及算法，以利于信号的准确采集和数据的快速处理；进一步完善结构，优化喷射系统的控制功能，提高整个喷射系统的可靠性，降低制造成本。总之，共轨式燃油喷射系统是一门综合性的新兴技术，其应用前景十分光明。

MTU's high-pressure common-rail diesel engine electronic injection system principles
The MTU4000 series and 8000 series diesel engine uses high-pressure common rail injection system, which in addition can be adjusted injection timing and injection quantity of its oil supply to the long duration of which can significantly reduce vibration and noise. The common rail injection system consists of high-pressure pump, pressure accumulator (fuel rail), fuel injectors and electronic control devices. The fuel injection principle is based on one or more dedicated high-pressure pump oil high-pressure accumulator system, with electronically controlled fuel injector to the same amount of oil in the entire injection time and the engine speed has nothing to do, its working principle shown in Figure 2. The high-pressure pump is a multi-cylinder radial piston pump, a gear driven by the engine front-end of the fuel share to the tubing along the engine vertical laying full-load pressure, each cylinder head and installed a fuel injection controlled by a solenoid valve connected to pass from the high-pressure pipeline would share the tubing injector; the fuel pressure in the fuel rail and injectors open, closed the moment the decision of each cylinder fuel injection quantity by the electronic device control; electronic devices installed The pressure in the fuel rail pressure sensor sensing system; fuel into the high-pressure pump through a throttle valve in the control of electronic devices, by throttling the flow to achieve the adjustment of the pressure; nozzle has a the control of fuel injection to stop the function, to control the fuel injection quantity and adjust the ignition delay of the fuel injection quantity and many other features; the injector needle valve above the pressure relief through a solenoid valve, fuel pressure control needle valve opening speed, began to move when the control valve discharge, an additional hydraulic valves, needle valve quick closing. This auxiliary servo injector can adjust the opening closed characteristics, the action is extremely accurate, fast response speed, able to control the idle period and the small amount of oil. High pressure fuel in the fuel rail, ready to go once a nozzle connected to the fuel into the cylinder through the nozzle. This high-pressure common-rail injection system to fuel the high pressure production and injection timing, quantitative completely separated, and the simple structure, but also a variety of speed in the engine (rated speed to idle) to provide the same injection pressure. In a wide speed range can provide the highest pressure, but share the actual pressure to the tubing is to be adjusted by the electronic control system, which according to the requirements of the engine power to take the best value.
4000 and 8000 series diesel engines used in high-pressure common rail fuel injection system injector structure is relatively simple, the solenoid valve at only a small control fuel injection process is easier to control, easy to implement pre-fuel injection. Particular in: High Pressure Common Rail injection system to precisely change the injection timing and fuel injection quantity and injection pressure. It can be to obtain a high injection pressure in extremely low diesel engine speed so as to effectively improve the emission targets. Improved fuel atomization performance of the high pressure common rail system, the maximum pressure than conventional fuel injection system reduced by 20%, thereby reducing consumption and fuel consumption rate of transmission machinery parts of the high-pressure system by force, improve the high-pressure system life, saving maintenance costs, and improve the economy.
High-pressure common rail injection system can all affect the combustion of the fuel injection parameters (such as fuel injection timing, process, time, pressure, etc.), a separate regulation, improve the mixture formation, so well adapted to the operating conditions. kinds of settings. Individually controlled fuel injection parameters will enable the engine to reduce fuel consumption and reduce emissions within the scope of the entire power curve, and is conducive to the improvement of ecological environment, to help reduce engine noise and vibration levels; high-pressure pump drive is no longer withstand the enormous torque peak; idle or low power range, cut off a single cylinder or cylinder group in order to prevent more emissions of hydrocarbons (white smoke), so either the minimum cost of electronic parameter control, but also for the injection process formation (such as pulse jet) provides the potential energy, so that the overall performance of the MTU4000 and 8000 series diesel engines to a new level.
The development trend of the four common-rail fuel injection system
Common rail fuel injection system is involved in the actuators, sensors, computers and control technology, the development trend: research and development of piezoelectric ceramic solenoid valves to meet the diesel engine electronically controlled common rail fuel injection system requires the solenoid valve has the ability to respond quickly to the work process precision, repeatability and reliability, good performance requirements; develop new types of intelligent sensors and advanced control model and algorithms, in order to facilitate the accurate collection of the signal and fast data processing; further improve the structure, optimize the injection system control functions, improve the entire injection system reliability, reduce manufacturing costs. In short, the common-rail fuel injection system is an integrated, emerging technologies, and its prospects are very bright.