In the application of automatic exhaust valve, sometimes it will be damaged. What is the reason for this? Let's take a look with Lianggong valve manufacturers.

1、燃油燃燒不好以及因此造成的結(jié)碳的影響。

1. Poor fuel combustion and the resulting carbon deposition.

燃燒不好不但會(huì)引起排溫升高，而且會(huì)在燃燒室形成結(jié)碳。排溫升高使排氣閥的工作環(huán)境更加惡劣，疊加其它情況后加劇了排氣閥的燒損。燃燒室中的結(jié)碳會(huì)有一部分隨著廢氣排出，它也會(huì)像前面說(shuō)的顆粒一樣卡在排氣閥和閥座的密封面上。

The combustion is not good, but it will increase the exhaust temperature and form carbon deposition in the combustion chamber. The increase of exhaust temperature makes the working environment of exhaust valve worse, and aggravates the burning loss of exhaust valve after superposition of other conditions. Part of the carbon deposit in the combustion chamber will be discharged with the exhaust gas, and it will also be stuck on the sealing surface of the exhaust valve and valve seat like the particles mentioned above.

尤其是重油的加熱溫度控制不佳，粘度太大造成噴入氣缸的燃油難以霧化，高壓油泵柱塞磨損造成的燃燒后移等原因引起的燃燒不好，會(huì)使排氣閥和閥座的密封面被積炭污染，加上燃油中含有的雜質(zhì)在經(jīng)過(guò)燃燒室內(nèi)的各種復(fù)雜熱過(guò)程后。

In particular, the heating temperature of heavy oil is not well controlled, the viscosity is too large, which makes it difficult to atomize the fuel injected into the cylinder, and the poor combustion caused by the backward combustion caused by the wear of the plunger of the high-pressure oil pump will pollute the sealing surface of the exhaust valve and valve seat by carbon deposition. In addition, the impurities contained in the fuel after various complex thermal processes in the combustion chamber.

在排氣閥閥盤(pán)及閥座密封錐面沉積成一層混有碳粒的玻璃狀較硬較脆物質(zhì)，其內(nèi)混有硫酸鈉、硫酸鈣、氧化鐵等物質(zhì)。當(dāng)此層玻璃狀沉積物沉積厚度過(guò)大時(shí)，在氣閥關(guān)閉時(shí)的撞擊力下會(huì)發(fā)生裂紋，反復(fù)撞擊后進(jìn)而發(fā)展成剝落，從而形成高溫燃?xì)鈬姵鐾ǖ朗箽忾y燒損。

A layer of glassy hard and brittle material mixed with carbon particles is deposited on the sealing cone of exhaust valve disc and valve seat, which is mixed with sodium sulfate, calcium sulfate, iron oxide and other substances. When the deposition thickness of this layer of glassy sediment is too large, cracks will occur under the impact force when the gas valve is closed, which will develop into spalling after repeated impact, so as to form a high-temperature gas injection channel and burn the gas valve.

燃油中含有不可燃燒的顆粒雜質(zhì)。

The fuel contains incombustible particulate impurities.

當(dāng)進(jìn)入燃燒室的油品中混有不可燃燒的雜質(zhì)顆粒物時(shí)，這些雜質(zhì)顆粒會(huì)隨著排氣排出氣缸，在排出的過(guò)程中會(huì)有一定的幾率在排氣閥關(guān)閉時(shí)被卡阻在排氣閥和閥座的密封面上。造成排氣閥不能完全關(guān)閉，這個(gè)卡住的顆粒雜質(zhì)的直徑有多大，氣閥的開(kāi)度就有多大。雖然能通過(guò)噴油器的噴孔進(jìn)入燃燒室的顆粒雜質(zhì)都較小，但在燃油混合氣體爆炸燃燒時(shí)，燃燒室的爆炸壓力很高，微小的氣閥開(kāi)度也能造成高溫高壓燃燒氣體的竄出。

When incombustible impurity particles are mixed in the oil entering the combustion chamber, these impurity particles will be discharged from the cylinder with the exhaust. During the discharge process, there is a certain chance that they will be stuck on the sealing surface of the exhaust valve and valve seat when the exhaust valve is closed. As a result, the exhaust valve cannot be completely closed. The diameter of the stuck particle impurities depends on the opening of the air valve. Although the particle impurities that can enter the combustion chamber through the nozzle hole of the fuel injector are small, the explosion pressure of the combustion chamber is very high during the explosive combustion of the fuel mixture, and the small opening of the gas valve can also cause the channeling of high-temperature and high-pressure combustion gas.

這時(shí)候竄出的燃燒氣體的溫度很高，瞬間的峰值接近2000℃，遠(yuǎn)遠(yuǎn)高于排氣沖程中流經(jīng)排氣閥密封面的廢氣溫度。排氣閥的密封面材料可以經(jīng)得起正常排氣時(shí)的廢氣的沖刷，但經(jīng)不起如此高壓和高溫的燃燒氣體的沖刷，很短的時(shí)間就會(huì)造成排氣閥燒損。

At this time, the temperature of the emitted combustion gas is very high, and the instantaneous peak value is close to 2000 ℃, which is much higher than the temperature of the exhaust gas flowing through the sealing surface of the exhaust valve in the exhaust stroke. The sealing surface material of the exhaust valve can withstand the scouring of exhaust gas during normal exhaust, but it can not withstand the scouring of combustion gas with such high pressure and high temperature, which will cause the burning loss of the exhaust valve in a very short time.

尤其閥門(mén)卡住的是混在重油中的氧化鋁和二氧化硅這些極硬顆粒，在造成排氣閥關(guān)閉不密的同時(shí)，普通排氣閥密封錐面在工作溫度下硬度并不是很高，沉積的硬質(zhì)燃燒產(chǎn)物顆粒在閉閥的撞擊下，還可使顆粒嵌入密封面，并在高溫燃?xì)獾臎_刷和燒蝕下出現(xiàn)凹坑，凹坑貫穿密封面后形成漏氣從而燒損氣閥。

In particular, the valve is stuck with extremely hard particles such as alumina and silica mixed in heavy oil. While the exhaust valve is not closed tightly, the hardness of the sealing cone of the ordinary exhaust valve is not very high at the working temperature. The deposited hard combustion product particles can also make the particles embedded in the sealing surface under the impact of the valve closing, and pits appear under the scouring and ablation of high-temperature gas, After the pit penetrates the sealing surface, an air leakage is formed, which burns the air valve.