Li Zhi returned to Fanjiazhuang and found an independent courtyard in the cannon workshop as a research place for steam engines. Pen & Fun & Pavilion www.biquge.info

The principle of the steam engine is very simple, it is nothing more than the use of the expansion pressure when the water is heated into steam to promote the piston movement, and then the vacuum suction piston movement generated when the steam is cooled into water, the combination of these two movements drives the piston to continuously push up and down, and then transmit power to the outside.

In later history, the practical steam engine appeared in the early eighteenth century, just a few decades after the twelfth year of Chongzhen. One of the more famous ones is the Newcastlemen steam engine. The principle of this steam engine is very simple, that is, after pushing the piston with the power of steam, cold water is injected into the cylinder to cool the steam, so that the vacuum generated can suck the piston back. Repeat these two movements, and the change can be transmitted outward.

Historically, several thousand units of this simple steam engine were produced and were widely used in coal mines in England to pump water from the mines. The use of this steam engine helped England become the largest coal producer in Europe in the early eighteenth century.

Li Zhi had never actually made a steam engine, so he decided to start with the simplest Newcastlemen steam engine, which was easy and then difficult. Make the Newcastlemen steam engine first, and then upgrade it.

However, to make a steam engine, the first thing Li Zhi had to do was a simple lathe. Without a lathe, you can't finish steel objects. Li Zhi has made a boring machine before, and the structure of the lathe is similar, except that one is a rotary boring cutter, and the other is a rotating object to be processed, but the same place is to rotate one thing to grind another, and the structure is similar.

Li Zhi instructed the blacksmith and spent five days making a simple lathe and making a turning knife from the crucible steel he had smelted. The resulting lathe can only be described as a primitive lathe - but it is enough for Li Zhi to use.

After the lathe is produced, it can be used to turn pistons. Li Zhi first had to make a cylinder with a diameter of 30 centimeters, first cast it with pig iron, and then finish it with a boring machine. Inside the boring machine, a piston with an same diameter of 30 centimeters is placed. Li Zhi had the blacksmith cast the shape from pig iron, and then the lathe finished it.

After repeated comparison, processing, re-comparison, and re-processing, Li Zhi finally obtained two cylinders and pistons that fit perfectly. Li Zhi put the cylinder with the chassis open on top of the boiling water and found that the piston did not leak at all. Even if the water vapor at a higher pressure is pressed, the air leakage rate will be very slow.

Lee Sik made a putter on the piston, which was pushed by a piston that moved up and down.

Then there is the cooling device, and Li Zhi fixes a cold water bucket next to the piston, which is connected to the bottom of the cylinder and has a valve at the connection. Make a mechanism control valve at the outermost end of the actuator, if the actuator is pushed to the top by water vapor, the mechanism is opened, and cold water is sprayed into the cylinder to cool the vapor. As soon as the water vapor cools, the piston drives the push rod downward, and when it reaches the bottom, it touches the mechanism to close the cold water gate, and so on.

Then it's time to make the boiler. This boiler must be large enough to produce enough vapor to propulsion. After the boiler is ready, it is connected to the cylinder, and the whole Newcastle door steam engine is ready.

It took Li Zhi five days to make the parts, screw the parts together, and began to test whether the work was successful.

As soon as the boiler was hot, Li Zhi found that the entire steam engine was leaking everywhere. There was not much air leakage between the finished piston and the cylinder, but the connections of those pipes were threaded together, and the gap was large, and water vapor was sprayed everywhere.

But even when there were leaks everywhere, the steam engine was successful because the water vapor in the boiler was burned out faster than the gas leaked in the pipes. The water vapor pushes the piston to do work, constantly moving up and down. Because of the air leakage at each pipe, the air pressure in the cylinder is just controlled, and the speed of the push rod moving up and down is relatively stable, up and down once in seven or eight seconds.

This Newcastle Gate steam engine can be regarded as made.

However, the Newcastle Gate steam engine was very inefficient, and it took a lot of wood to produce a limited amount of thrust. This is because cooling the water vapor in the cylinder also cools the cylinder block, and then after a while, the hot steam comes in and heats the cylinder block, wasting a lot of heat back and forth. Such an inefficient steam engine obviously could not meet Li Zhi's needs, and Li Zhi wanted to gradually transform this Newcastlemen steam engine into a Watt steam engine.

Watt's biggest improvement to the Newcammen steam engine was the condenser. With a condenser, the cylinder block is not repeatedly heated and cooled.

The condenser is actually a large iron canister connected to a cylinder with cold water in it. The switch of the condenser is controlled by a mechanism, and when the piston is pushed to the top, the switch is turned on and the vapor enters the condenser to cool into water. When the piston falls to the bottom, the switch is turned off, and the vapor has nowhere to escape and collect in the cylinder, pushing the piston up again.

But when making the condenser, Li Zhi found that the condenser required a higher air pressure than the method of water spray cooling, and the air pressure could not be gathered in the leaking pipes everywhere, so he had to find a way to block the leakage.

But there is no high-temperature resistant rubber these days, and Li Zhi thought about it, but he didn't think of what he could use to plug the leaking pipe. Li Zhi had no choice but to test the softer materials available on the market one by one. But I tried all kinds of textiles, and the results were not good. The silk, which looked very slippery and soft, was burned by the high temperature steam, and it became charred and clumpy. The material that is more resistant to high temperature is linen, but the pore size of linen cloth is large, and it cannot block the leakage of vapor.

After testing for several days, Li Zhi still couldn't find a material that could plug the air leak, and Li Zhi was a little stumped. The principle of this watt-type steam engine is simple, but the details are still very complicated, even if one detail is not done well, it cannot drive the whole steam engine to run.

Speaking of copper, or lead is relatively soft, and can withstand hundreds of degrees of high temperatures, is it necessary to use copper and lead as pipe joints? It's a lot of trouble to do.

A young blacksmith who was transferred by Li Zhi to make a steam engine watched Li Zhi make a Newcastle Gate steam engine like a trick these days, and he admired Li Zhi very much. At this time, he saw that Li Zhi was in trouble, and interjected: "General, if you soak the linen cloth in oil for a day, the aperture in the linen cloth will be blocked by the grease, which may be useful." ”

Li Zhi was stunned, but he didn't expect that there would be such a way.

He patted the young blacksmith on the head and did as he did. Wrap the oil-soaked linen cloth around the threaded connector, tighten the connector, and restart the steam engine.

At this moment, Li Zhi found that there was no air leakage on the pipe.

Li Zhi said to the young blacksmith: "The suggestion is good, reward you with ten taels of silver!" ”

The young blacksmith had earned ten taels of silver with a single word, and was so overjoyed that he was so smiling that his mouth almost reached the back of his head. (To be continued.) )