How was the steam engine invented?

The history of steam engines can be traced back to ancient Greece. In 50 AD, Heron invented a steam wheel ball for demonstration. When heated steam is ejected from the nozzle, the roller ball will rotate in the opposite direction. But at that time, this creative achievement was not applied in practice, and the inventor himself did not intend to do so. 1000 years later, when industry and mining industry developed, someone tried to make a steam pump to discharge water from the mine. 1630, a steam-powered water pump was invented and patented, but all activities were limited to design or trial production, which had no practical value. In fact, only German D Papin, British T savery and T newcomen were the inventors of the steam engine.

Savery is an English engineer. During the period of 1689 ~ 17 12, he successively created several steam engines. Among them, there is a machine that is directly used to lift water. Its working principle is: steam enters the air bag from the boiler through the open valve, and then the water is forced into the water storage tank through the movable valve (at this time, the other movable valve is closed). When there is little water left in the airbag, the valve is closed, and the water is discharged from the water tank to cool the airbag, thus forming a negative pressure in the airbag (negative pressure means that the air pressure here is lower than atmospheric pressure). Under the action of atmospheric pressure, water enters the airbag from the straw through the movable valve (at this time, the other valve is closed). This cycle is repeated to achieve the purpose of continuous pumping. It is said that this steam engine is only 7 meters high and can lift more than ten tons of water per hour, but someone needs to close the valve every ten seconds. If you forget to open and close the valve in time, it may cause the boiler to explode. Coupled with the deep mine, it is often necessary to use several steam engines to lift water in several steps, which is neither economical nor safe, so the mine owners are reluctant to use it.

Newcomen's steam engine is the product of further improvement on the basis of Savili's steam engine. Newcomen is a blacksmith. He added a huge rocker arm to the piston, hung a balance weight on one side of the rocker arm, and connected a sucker rod for pumping oil under the balance weight. When the weight of the weight drops, the piston is pulled to rise, and steam enters the airbag from the boiler through the open valve. At this time, the valve is closed, the water gate of the airbag is opened, and cold water enters the airbag from the water tank, so that steam condenses and negative pressure is formed in the airbag. Under the action of atmospheric pressure, the piston moves downward and lifts the sucker rod.

The advantage of newcomen steam engine is that the air pump in the power part is separated, and the air pressure is lower and safer. Later, someone changed the process of valve opening and closing to flywheel, which realized automation, so many mines were willing to adopt it.

The efficiency of newcomen's steam engine was very low, and it was not until1769 j watt was further improved that the steam engine was widely used.

Watt is a Scottish inventor. He was born in a worker's family in Greenock on June 9, 763. Due to the influence of his family, he was familiar with the basic knowledge of mechanical manufacturing since he was a child. /kloc-when he was 0/8 years old, he was an apprentice in a watch shop in London and learned the skills of using tools and manufacturing instruments. He used his spare time to study hard and practice hard, and mastered the manufacturing technology of complex instruments such as compass, quadrant and theodolite. Later, Watt went to the University of Glasgow to take charge of the maintenance of teaching instruments. During the repair work, he became more familiar with the structure of this steam engine, made clear its principle and found out the reasons for its low efficiency. It turns out that cold water is injected into the cylinder of newcomen steam engine every time the piston is pushed to condense steam, so the cylinder is heated repeatedly, which consumes a lot of heat energy in vain. 1769, watt invented the condenser, the process of manufacturing precision cylinders and pistons, and the single-acting steam engine. After constant experiments, he invented a double-acting steam engine to push the piston from both sides of the cylinder. He used crank mechanism to convert reciprocating linear motion into rotary motion. He also designed a centrifugal economizer to control the speed of the steam engine. After a series of innovations, the steam engine was gradually improved and its efficiency was greatly improved. The widespread use of steam engines in industry promoted the coming of the industrial revolution.