The engine is the core part of the automobile, and its reliable quality is the basis for the excellent durability of the whole vehicle. It is rumored that the reason why Japanese automobile companies can make their products generally have high durability is that they assemble the engine in a low temperature environment. Is this really the case? Why should Japanese engines be assembled at low temperature? What’s so special about it?
First of all, it is true that most Japanese automobile companies have the assembly process of low-temperature assembly engine, but this is not their proprietary technology. Many automobile enterprises all over the world have been using low-temperature assembly. This method is not only not a secret in the industry, but also used in many manufacturing industries besides automobile manufacturing. However, not all engine components have to be assembled at low temperature. Simply speaking, for some parts of the engine, this is to achieve “interference fit”, which is to rely on the interference value between the shaft and the hole parts to achieve a tight and firm connection after the assembly by relying on the elastic pressure of the contact surfaces. However, in the complete assembly process of the engine, some parts need to Interference fit, and some need clearance fit.
In addition, there is another point to be noted, that is, assembly at low temperature is only a way to achieve the goal of “interference fit”, which is called “cold assembly fit”. Specifically, it is to treat the parts that are too large to be assembled smoothly at low temperature. With the help of the characteristics of thermal expansion and cold contraction of materials, the volume can be reduced so that it can be easily assembled, and then it can be achieved after returning to normal temperature The purpose of “interference fit” is to use the similar principle of “hot fit” and “press fit” to realize the “interference fit” between parts. And even if it is “cold fitting”, it is not necessary to keep the whole assembly environment at low temperature, which will greatly increase the cost of automobile manufacturing. As long as the engine parts which need to be “interference fit” are cold treated to keep them in a low temperature state.
To sum up, the Japanese engine is not assembled in a low temperature environment, but a part of the engine parts are cold treated for “cold fitting”, so as to make the connection between them more tight and reliable, which plays a significant role in ensuring the assembly accuracy, and has a positive significance for improving the quality stability of the engine.