【正文】 隨著人們對(duì)低油耗、低廢氣排放、發(fā)動(dòng)機(jī)低噪聲的需求越來(lái)越大，對(duì)發(fā)動(dòng)機(jī)和燃油噴射系統(tǒng)的要求也越來(lái)也高。更高的壓力、更快的開(kāi)關(guān)時(shí)間，以及根據(jù)發(fā)動(dòng)機(jī)工況修訂的可變的流量速率曲線(xiàn)，已經(jīng)使得柴油發(fā)動(dòng)機(jī)具有良好的經(jīng)濟(jì)性、低污染、高動(dòng)力性，因此柴油發(fā)動(dòng)機(jī)甚至進(jìn)入了豪華高性能轎車(chē)領(lǐng)域。同時(shí)，噴油量必須精確計(jì)算，燃油流量速率曲線(xiàn)必須有精確的計(jì)算模型，預(yù)噴射和二次噴射必須能夠完成。共軌系統(tǒng)包括以下幾個(gè)主要的部分： ①低壓部分，包含燃油共軌系統(tǒng)組件。電控柴油機(jī)系統(tǒng)EDC主要由系統(tǒng)模塊，如傳感器、電子控制單元和執(zhí)行機(jī)構(gòu)組成。它們擁有一個(gè)可以快速開(kāi)關(guān)噴嘴的執(zhí)行閥(電磁閥或壓電觸發(fā)器)，這就允許對(duì)每個(gè)氣缸的噴射進(jìn)行控制。在共軌燃油噴射系統(tǒng)中，燃油噴射和壓力的產(chǎn)生是分開(kāi)的。EDC控制每個(gè)組件。燃油噴射和壓力的產(chǎn)生是通過(guò)蓄能器分離開(kāi)來(lái)。由發(fā)動(dòng)機(jī)驅(qū)動(dòng)的連續(xù)運(yùn)轉(zhuǎn)的高壓泵提供所需噴油的壓力。由于幾乎一致的噴油方式，高壓泵的設(shè)計(jì)可以小的多，而且它的驅(qū)動(dòng)轉(zhuǎn)矩可以比傳統(tǒng)燃油噴射系統(tǒng)低，這源于高壓泵的負(fù)載很小。(2)壓力控制所應(yīng)用的壓力控制方法主要取決于系統(tǒng)。不需噴射的燃油通過(guò)壓力控制閥流回到低壓回路。在第一批共軌系統(tǒng)中采用了對(duì)高壓側(cè)的控制。另一種控制軌道壓力的方式是進(jìn)口端控制燃油供給。發(fā)生故障時(shí)，壓力安全閥防止油軌壓力超過(guò)最大值。這對(duì)燃油消耗起到積極的作用。雙執(zhí)行器系統(tǒng)也是一種控制軌道壓力的方式，它通過(guò)計(jì)算單元對(duì)壓力進(jìn)行控制，并且通過(guò)壓力控制閥對(duì)高壓端進(jìn)行控制，因此同時(shí)具備高壓側(cè)控制與進(jìn)口端燃料供給控制的優(yōu)勢(shì)。它們由與燃油軌道直接相連的短高壓油軌提供燃油。噴油器的開(kāi)啟時(shí)間和系統(tǒng)油壓決定了燃油供給量。(4)液壓輔助動(dòng)力與傳統(tǒng)燃油噴射系統(tǒng)相比，將壓力的產(chǎn)生與燃油的噴射分離開(kāi)來(lái)，有利于燃燒室的充分燃燒。目前最高燃油壓力為1600巴，將來(lái)會(huì)達(dá)到1800巴。通過(guò)多次觸發(fā)高速轉(zhuǎn)換閥的開(kāi)閉可以在每個(gè)噴射周期內(nèi)實(shí)現(xiàn)多達(dá)5次的噴射。(5)控制和調(diào)節(jié)發(fā)動(dòng)機(jī)的控制單元通過(guò)傳感器檢測(cè)加速踏板的位置以及發(fā)動(dòng)機(jī)和車(chē)輛的當(dāng)前工況。電控單元處理輸入信號(hào)。噴油器的開(kāi)關(guān)時(shí)間應(yīng)很短，采用優(yōu)化的高壓開(kāi)關(guān)閥和專(zhuān)業(yè)的控制系統(tǒng)即可實(shí)現(xiàn)。電控柴油機(jī)系統(tǒng)(EDC)可以實(shí)現(xiàn)對(duì)燃油噴射量的精確計(jì)算。其基本功能包括對(duì)柴油燃油噴射正時(shí)的精確控制，和在給定壓力下對(duì)油量的控制。其他開(kāi)環(huán)和閉環(huán)控制功能用于減少?gòu)U氣排放和燃油消耗，或提供附加的可靠性和便利性，具體例子有：① 廢氣在循環(huán)控制； ② 增壓控制； ③ 巡航控制；④ 電子防盜控制系統(tǒng)等。由于發(fā)動(dòng)機(jī)控制單元通常最多有8個(gè)噴油器輸出口，所以超過(guò)八缸的發(fā)動(dòng)機(jī)需要兩個(gè)控制單元。一些功能被 分配給某個(gè)特定的控制單元(如燃料平衡控制)，其功能根據(jù)需求情況(如檢測(cè)傳感器信號(hào))可以動(dòng)態(tài)地分配給一個(gè)或多個(gè)控制單元。② The highpressure system, prising ponents such as the highpressure pump, fuelrail, injector, and highpressure fuel electronic diesel control(EDC), consisting of system modules, such as sensors, the electronic control unit, and key ponents of the monrail system are the are fitted with a rapidaction valve(solenoid valve or piezotriggered actuator)which opens and closes the permits control of the injection process for each the injectors are fed by a mon fuel rail, this being the origin of the term “mon rail”.In the monrail fuelinjection system, the function of pressure generation and fuel injection are injection pressure is generated independent of the engine speed and the injected fuel electronic diesel control(EDC)controls each of the ponents.(1)Pressure generation and fuel injection are separated by means of an accumulator under pressure is supplied to the accumulator volume of the monrail ready for continuously operating highpressure pump driven by the engine produces the desired injection in the fuel rail is maintained irrespective of engine speed or injected fuel to the almost uniform injection pattern, the highpressure pump design can be much smaller and its drivesystem torque can be lower than conventional fuelinjection results in a much lower load on the pump highpressure pump is a radialpiston mercial vehicles, an inline fuelinjection pump is sometimes fitted.(2)Pressure Control The pressure control method applied is largely dependent on the way of controlling rail pressure is to control the highpressure side by a pressurecontrol not required for injection flows back to the lowpressure circuit via the pressurecontrol type of control loop allows rail pressure to react rapidly to changes in operating point( the event of load changes).Control on the highpressure side was adopted on the first monrail pressurecontrol valve is mounted preferably on the fuel some applications, however, it is mounted directly on the highpressure way of controlling rail pressure is to control fuel delivery on the suction metering unit flanged on the highpressure pump makes sure that th