Development of corrugated pipe

This is really an extremely simple and ingenious invention. In a rectangular box, there is an air inlet at both ends of the box: when the rectangular box is pulled out by hand, air is inhaled from the far end; When it is pushed, air is sucked in from the near side. In the process of inward and outward, air is sucked into the box; In both cases, compressed air is pushed into one side of the chamber and discharged through the exhaust port. It can not only blow air, but also spray liquid. In Laozi's philosophical masterpiece, it is described as follows: the more you push and pull, the greater the air volume you give. Isn't heaven and earth like bellows? Although it is empty, it will never be exhausted. Although it is traditionally believed that Laozi wrote in the 6th century BC, the most conservative estimate is around the 4th century BC, both of which may be correct. The third sentence in this paper is very important because it seems to refer to the continuous action of double-acting piston bellows. Laozi's Oral Classic uses it to describe the space "between heaven and earth, is it still charming?" Empty and unyielding, move out. That is, the leather container is filled with air without collapsing. Pull the movable wooden box by hand to squeeze out the air inside. Air can enter the furnace through an air duct.

There are many people who talk about verve in ancient books of Han Dynasty. A map of iron smelting stone in Han Dynasty was unearthed in tengxian, Shandong Province. It has three wooden rings, two round plates and leather. Open the leather bottle, and air enters through the air inlet valve; The compressed air in the leather container enters the air duct through the exhaust valve and then enters the melting furnace. This is a single container operation. At the latest in the Warring States period, a device consisting of multiple containers connected in parallel or in series appeared, which was also called "container release" in the Han Dynasty.

Double-acting piston bellows is China's most important invention in blowing technology, which appeared in Tang Dynasty or Song Dynasty. 1280 printed "The Battle of Birds No.3" has a picture of the world's oldest double-acting piston bellows. According to legend, this book was written by Yuan Tiangang in the early Tang Dynasty and was first published in the Song Dynasty. The piston bellows contained in the Ming dynasty heavenly creations are similar to this. The piston bellows does useful work in both forward and backward strokes. When the movable wooden box is pulled by hand, one end exhausts and the other end inhales the same amount of air in each stroke, so it can provide continuous airflow and improve the efficiency of blowing, which is a remarkable progress in blowing technology. In Europe, until AD 17 16, Fang Faming introduced a similar double-acting reciprocating pump, which paved the way for later piston machinery.