Do you know what cavitation is? First of all, let's take a look at the cavitation phenomenon of concrete mixer.

气蚀现象：发生在发动机燃烧室的周围，虽然我们从车辆水温表的反馈来看是在90°左右，但发动机燃烧做功，特别是大多数湿式气缸套，局部表面的温度超过水的沸点，要高出一大截。水在沸点附近，会产生大量气泡，这部分气泡反复冲击气缸套表面，微观下的冲击波的压力达到15-20000PSI。我们日常生活中茶壶烧水，滚水沸腾时壶底产生的气泡，道理相似。

Cavitation: it occurs around the combustion chamber of the engine. Although it is about 90 ° according to the feedback from the vehicle water temperature gauge, the work done by the engine combustion, especially for most wet cylinder liners, the local surface temperature is higher than the boiling point of water, which is much higher. When the water is near the boiling point, a large number of bubbles will be produced. These bubbles repeatedly impact the surface of cylinder liner, and the micro shock wave pressure reaches 15-20000 psi. In our daily life, when the teapot is boiling, the bubble at the bottom of the pot is similar.

发动机使用的冷却液，通常沸点温度超过130度。如果破坏冷却液的成分比例，乙二醇成分减少。气缸套暴露在较低的沸点下，醇类物质无法附着在表面。穴蚀发生将无法避免，例如200小时后，兑水后的冷却液实验，康明斯Cummins NTC400发动机已经产生缸套激烈气蚀情况，产生更严重的穴蚀。

The coolant used in the engine usually has a boiling point of more than 130 degrees. If the composition ratio of the coolant is destroyed, the glycol composition will be reduced. The cylinder liner is exposed to a lower boiling point and alcohols cannot adhere to the surface. Cavitation will not be avoided. For example, 200 hours later, the coolant test after mixing water shows that Cummins ntc400 engine has produced severe cavitation of cylinder liner, resulting in more serious cavitation.

为什么有些全混凝土搅拌机的发动机加水表面看起来很正常?

Why do some all concrete mixers have normal engine water surfaces?

全自动混凝土搅拌机

Automatic concrete mixer

中等排量发动机：冷却系统要求不高 腐蚀状况较突出

Medium displacement engine: low requirement of cooling system and serious corrosion

国内中等排量的发动机，从上世纪70年代技术上演变而来，仅相当于国外50年代的水平，本质上并没有改变。因此发动机设计之初，冷却系统要求不高，燃烧室并没有强化，气蚀现象同样存在，但并非明显感受，相比腐蚀状况就比较突出，例如烂水堵。

China's medium displacement engine, developed from the 1970s, is only equivalent to the level of foreign countries in the 1950s, essentially unchanged. Therefore, at the beginning of engine design, the cooling system requirements are not high, the combustion chamber is not strengthened, cavitation phenomenon also exists, but it is not obvious. Compared with the corrosion situation, it is more prominent, such as rotten water blocking.

现今国产大排量卡车发动机，采用了增压，高压缩比，活塞行程缩短，转速更低，这样的强化设计，燃烧室的局部温度，强制散热要求，多通过活塞机油喷嘴，更高的冷却液循环量，和使用更高沸点温度的冷却液来实现。因此冷却液少量补充水，短期内可以应急，长时间使用弊大于利，一个局部频繁“开锅”的发动机，寿命大大缩短。

Nowadays, the domestic large displacement truck engine adopts supercharging, high compression ratio, shorter piston stroke and lower speed. Such enhanced design, local temperature of combustion chamber and forced heat dissipation requirements are mainly realized by piston oil nozzle, higher coolant circulation volume and higher boiling point temperature coolant. Therefore, a small amount of coolant water can be used as an emergency in a short time, and the disadvantages outweigh the advantages of long-term use. The service life of an engine with local frequent "boiling" is greatly shortened.

今天这篇文章为大家讲解了混凝土搅拌机的气缸套致命气蚀穴蚀的知识，大家以后再遇见这种情况应该可以很好的了吧！

Today, this article explains the knowledge of the fatal cavitation and cavitation of the cylinder liner of the concrete mixer. We should be able to solve this problem in the future!