車廠說定期用高轉速來跑來清積碳
請問除了上述方法 保時捷cayenne 柴油車需要去拆零件清積碳嗎
如果需要清, 有推薦的保養廠嗎
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ajuggrutaiwan wrote:
柴油引擎沒有混合比這事(恕刪)
柴油引擎沒有混合比,這是錯的,有噴柴油進引擎引爆,就有空燃比.
國外拆進氣歧管.
https://ultimatedieseltuning.com.au/articles/egr-the-ugly-truth/
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ajuggrutaiwan wrote:
柴油引擎壓縮空氣後再噴入柴油使其自燃⋯何來柴油與空氣的混合比？(恕刪)
這樣就有混合比,你是不是重點在混合?問題是混合比又稱"空燃比"，英文的寫法是"A/F"，即Air/Fuel ratio，空氣對燃油的比例。
空氣對燃油的比例,請問有柴油噴入引擎燃燒,是不是就有比例?
柴油引擎如果沒有空燃比,那排氣歧管上為何有空燃比感知器?
https://dieselnet.com/tech/diesel_combustion.php
柴油燃燒的特徵在於稀薄的總空燃比。通常在峰值扭矩條件下發現最低的平均空燃比。為了避免過多的煙霧形成，峰值扭矩下的空燃比通常保持在25：1以上，遠高於化學計量（化學上正確）的當量比14.4：1。在渦輪增壓柴油發動機中，怠速時的空燃比可能會超過160：1。因此，在燃料燃燒之後，存在於氣缸中的過量空氣在整個燃燒和膨脹過程中繼續與燃燒的氣體和已經燃燒的氣體混合。在排氣門打開時，多餘的空氣與燃燒產物一起被排出，這解釋了柴油機廢氣的氧化性質。儘管燃燒發生在汽化燃料與空氣混合後，但形成了局部富集但可燃的混合物，達到適當的點火溫度後，總的空燃比變稀。換句話說，引入柴油發動機的氣缸中的大部分空氣被壓縮和加熱，但從未參與燃燒過程。過量空氣中的氧氣有助於氧化氣態碳氫化合物和一氧化碳，從而將其減少到廢氣中的極低濃度。
Diesel combustion is characterized by lean overall A/F ratio. The lowest average A/F ratio is often found at peak torque conditions. To avoid excessive smoke formation, A/F ratio at peak torque is usually maintained above 25:1, well above the stoichiometric (chemically correct) equivalence ratio of about 14.4:1. In turbocharged diesel engines the A/F ratio at idle may exceed 160:1. Therefore, excess air present in the cylinder after the fuel has combusted continues to mix with burning and already burned gases throughout the combustion and expansion processes. At the opening of the exhaust valve, excess air along with the combustion products are exhausted, which explains the oxidizing nature of diesel exhaust. Although combustion occurs after vaporized fuel mixes with air, forms a locally rich but combustible mixture, and the proper ignition temperature is reached, the overall A/F ratio is lean. In other words, the majority of the air inducted into the cylinder of a diesel engine is compressed and heated, but never engages in the combustion process. Oxygen in the excess air helps oxidize gaseous hydrocarbons and carbon monoxide, reducing them to extremely small concentrations in the exhaust gas.
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altezzaclio wrote:我講的是沒有‘混合比’是指像汽油引擎那樣在進氣行程時噴入汽油讓空氣與汽油那般混合，你講的是空氣跟燃料的比例⋯柴油引擎空氣都是固定的，引擎快慢跟馬力就是靠噴入的柴油量來控制的。
這樣就有混合比,你是(恕刪)
下面有動畫，請自行研究一下吧！
柴油引擎跟汽油引擎不同處
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ajuggrutaiwan wrote:
我講的是沒有‘混合比’！是指像汽油引擎那樣在進氣行程時噴入汽油讓空氣與汽油那般混合，你講的是空氣跟燃料的比例⋯柴油引擎空氣都是固定的，引擎快慢跟馬力就是靠噴入的柴油量來控制的。(恕刪)
那你不能講沒有‘混合比’,你要講沒有空氣和燃料混合的動作.混合比就是空燃比,不能誤用.
柴油引擎空氣都是固定的,這句話不對.有增壓和怠速時,汽缸填充的空氣量有一樣?
你不用叫我研究,我就是汽車科本科系,才會糾正你的說法.
柴油和空氣實際上是有混合的.
在柴油發動機中，燃料通常在壓縮衝程即將結束時被噴射到發動機氣缸中，即在上止點之前幾度的曲柄角[ Heywood 1988 ]。。液體燃料通常以一個或多個射流的形式通過噴油嘴頂端的小孔或噴嘴以高速噴射。它霧化成小液滴並滲透到燃燒室中。霧化的燃料從周圍的加熱壓縮空氣中吸收熱量，蒸發並與周圍的高溫高壓空氣混合。隨著活塞繼續移近上止點（TDC），混合氣（主要是空氣）溫度達到燃料的著火溫度。在點火延遲時間後，一些預混合的燃料和空氣迅速點火。這種快速點火被認為是燃燒的開始（也是點火延遲時間的結束），其特徵是隨著燃油-空氣混合物的燃燒，氣缸壓力急劇增加。由預混燃燒產生的壓力升高會壓縮和加熱裝料的未燃燒部分，並縮短點火之前的延遲時間。這也增加了剩餘燃料的蒸發速率。霧化，汽化，燃料蒸氣與空氣的混合以及燃燒持續進行，直到所有噴射的燃料都燃燒完畢。
In diesel engines, fuel is often injected into the engine cylinder near the end of the compression stroke, just a few crank angle degrees before top dead center [Heywood 1988]. The liquid fuel is usually injected at high velocity as one or more jets through small orifices or nozzles in the injector tip. It atomizes into small droplets and penetrates into the combustion chamber. The atomized fuel absorbs heat from the surrounding heated compressed air, vaporizes, and mixes with the surrounding high-temperature high-pressure air. As the piston continues to move closer to top dead center (TDC), the mixture (mostly air) temperature reaches the fuel’s ignition temperature. Rapid ignition of some premixed fuel and air occurs after the ignition delay period. This rapid ignition is considered the start of combustion (also the end of the ignition delay period) and is marked by a sharp cylinder pressure increase as combustion of the fuel-air mixture takes place. Increased pressure resulting from the premixed combustion compresses and heats the unburned portion of the charge and shortens the delay before its ignition. It also increases the evaporation rate of the remaining fuel. Atomization, vaporization, fuel vapor-air mixing, and combustion continue until all the injected fuel has combusted.
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