由發動機前端的一套齒輪驅動，將燃油以全負荷壓力提供給沿發動機縱向鋪設的共用給油管，每個氣缸蓋上裝一個由電磁閥控制的噴油器，由高壓油管將共用油管與噴油器相連通；油軌中的燃油壓力及噴油嘴開、閉的時刻決定了各缸的噴油量，這些都由電子裝置控制；電子裝置通過裝在油軌前的壓力傳感器感知系統中的壓力；而燃油是通過一節流閥進入高壓泵的，在電子裝置的控制下，通過對流量的節流實現對壓力的調整；MTU高壓共軌柴油發動機|MTU高壓共軌柴油發動機維修技術|MTU高壓共軌柴油發動機電子噴射系統原理資料|MTU高壓共軌柴油發動機維修服務商噴油嘴則具有控制噴油開始、停止的功能，從而控制噴油量以及調整著火延遲期噴油量等多項功能；該噴油嘴通過一個電磁閥使針閥上方泄壓，然后由燃油壓力控制針閥的開啟速度，當控制閥泄流后，一個附加的液壓閥開始動作，使針閥快速關閉。這種輔助伺服式噴油嘴能分別調整開啟、關閉的特性，動作極其精確，具有極快的反應速度，能夠控制怠速期間及小的供油量。高壓燃油在油軌中蓄勢待發，一旦某一噴油嘴接通，燃油即通過噴油嘴進入氣缸。這種高壓共軌式噴射系把燃油的高壓產生與噴射的定時、定量完全分開，并且結構簡單，還能在發動機各種轉速（從額定轉速到怠速）下提供相同的噴射壓力。雖然在很寬的轉速范圍內都能提供最高壓力，但共用給油管的實際壓力是由電子控制系統進行調節的，從而可根據發動機功率要求而取最佳值。

4000和 8000系列柴油機所采用的高壓共軌燃油噴射系統具有噴油器結構相對簡單，在電磁閥處僅有小的控制油量，噴油過程易于控制，容易實現預噴油等優點。具體表現在：高壓共軌式噴射系統能夠精確地改變噴油定時、噴油量及噴油壓力。它可在極低的柴油機轉速下也獲得高的噴射壓力，從而有效地改善排放指標。由于燃料霧化性能的改善，高壓共軌系統的最高壓力可比傳統的噴油系統降低 20%左右，從而降低了高壓系統的零件受力、傳動機械能的消耗及燃油消耗率，提高了高壓系統的使用壽命，節約了維修保養的費用，提高了經濟性。

高壓共軌式噴射系統可對所有影響燃燒的燃油噴射參數（如燃油噴射正時、過程、時間、壓力等）單獨進行調控，改善混合氣的形成，使之能很好適應運行工況的各種設定。單獨控制燃油噴射參數可使發動機在整個功率曲線范圍內減少燃油消耗和降低廢氣排放，有利于生態環境的改善，有助于降低發動機的噪聲和振動水平；高壓泵驅動裝置不再承受巨大的扭矩峰值；在惰轉或較低的功率范圍內，切斷單個氣缸或氣缸組，以防止較多的碳氫化合物（白煙）的排放，這樣既可以最小的費用實現電子參數控制，還為噴射過程的形成（如脈沖式噴射）提供了勢能，使 MTU4000和 8000系列柴油機的整體性能提高到了一個新的高度。

4共軌式燃油噴油系統的發展趨勢

共軌式燃油噴射系統涉及到執行器、傳感器、計算機及控制技術，發展趨勢為：研究開發壓電陶瓷電磁閥，以滿足柴油機電控共軌燃油噴射系統要求電磁閥具有快速響應能力、工作過程精確、重復性和可靠性好的性能要求；研制新型智能型傳感器和采用先進的控制模式及算法，以利于信號的準確采集和數據的快速處理；進一步完善結構，優化噴射系統的控制功能，提高整個噴射系統的可靠性，降低制造成本。總之，共軌式燃油噴射系統是一門綜合性的新興技術，其應用前景十分光明。

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.