Four-stroke radial reciprocating engine.
What is a four-stroke
The concept of four-stroke became clear after they developed the internal combustion engine.
The first step: inhalation, intake stroke.
Second step: compression stroke.
The third step: work, ignition stroke.
Step Four: Exhaust Stroke.
This is a four-stroke.
The four-stroke is far more powerful than the two-stroke. Steam engines fall into the category of two-stroke.
They understand that four-stroke is definitely the category of internal combustion engines.
But the radial reciprocating engine, this star shape, made them a little blind.
The people in the class had a heated discussion and walked up to the podium one after another to carefully observe the blackboard, but they couldn't help but be confused. It seems that I understand, but I don't seem to understand.
Li Zhen asked everyone to get down, and then used chalk to draw a line on one of the corners, which read: "Piston."
Put down the chalk and say: "Every 'angle' you see growing around a circle is a piston cylinder. And if I want to tell you about the radial reciprocating engine, I cannot avoid another concept: the cylinder block."
"What is a cylinder? Who can answer this?"
A person from the mechanical engineering institute stood up and said: "It's the cylinder. It carries the piston, push rod, and transmission rod. One end is connected to the power source, and the other end is responsible for power output, which is the cylinder block."
Li Zhen asked again: "Why were the previous internal combustion engines less powerful? Do you understand now?"
Ma Jianbin exclaimed: "I understand. I suddenly understand, Master Li, I understand this picture. Because... the previous internal combustion engine only had one cylinder. If you have to plan, it is a single-cylinder engine. And Li The one the artist drew is a multi-cylinder engine. A single-cylinder engine has only one cylinder to provide power, and the reciprocating speed is slow and the torque is relatively small. But this multi-cylinder engine uses multiple cylinders to provide power at the same time, and the reciprocating speed will be geometric. Multiplied.”
Li Zhenyi clapped his hands:
"Yes, this is a multi-cylinder engine. The radial reciprocating engine squeezes out the potential of the four-stroke engine infinitely. For example, if the speed of the horizontal-bar engine is five revolutions per second. Then the speed of the five-cylinder engine , it can reach at least twenty-five revolutions per second. Let me ask the most practical question, do you think the cylinder has a service life?"
"have!"
"There must be some."
"The piston keeps moving in the cylinder, which will cause wear and tear."
“…”
"Suppose a single-cylinder engine has to work 400,000 revolutions a day. Then the reverse deduction proves that the cylinders of this engine will be worn 400,000 times a day. If a five-cylinder engine also works 400,000 revolutions a day. The 400,000 times of wear will be caused by five The cylinders are divided equally. Theoretically, the service life will be five times that of the horizontal-bar engine. This is the most realistic issue. Stability."
"Then, if a single-cylinder engine works at 400,000 rpm, it takes an hour. Then the theoretical time required for a five-cylinder engine to work at 400,000 rpm will be shortened by five times. So the speed will be faster. The torque will be greater. That’s how multi-cylinder engines work.”
Ma Jianbin's face flushed because of the surprise. He felt that his eyes had been opened. How does Master Li's head grow
He actually studied mobility to such an extent.
It feels simple after I explain it clearly, but you can imagine how difficult it is to create something from scratch.
The same power, but with just a few more cylinders, the power increases exponentially. Stability, safety, torque, and speed are all improved geometrically.
Ma Jianbin exclaimed: "Master Li, I already understand the principle. This concept is an enlightenment for us. Once we have the concept, the next step is the technical issue of the ending. We will immediately put it on the agenda and start research."
Li Zhen waved his hand: "Sit down first. I haven't finished speaking yet."
"The technical issues of multi-cylinder engines are not as complicated as you think. This issue will be dealt with later. In addition, I would like to say that multi-cylinder engines are not suitable for aviation because they are too heavy. The body is complex and huge. If the technology is mature, it can To replace steam locomotives."
After hearing the words, everyone sat up straight again and listened with their ears pricked up.
Li Zhen pointed to the picture on the blackboard: "And what I really want to say is the radial reciprocating engine. This is the heart of aerospace applications. After understanding the concept of multi-cylinder engines, understanding the radial engine becomes It’s easy.”
"First of all, a few concepts, why I say that radial engines are suitable for aviation. First, it has a compact structure and takes up little space. Second, it is light in weight. Third, it has high power compression strength. Fourth, it has strong stability and safety. It has strong performance and long service life. Fifth, the radial engine can even realize a double-row star, a three-row star, or even a multi-row star."
"The cylinders are arranged around the rotor body. I don't need to emphasize the issue of the transmission coupling. What must be emphasized is that the number of cylinders in a radial reciprocating engine must be an odd number. It cannot be an even number."
Liu Jinghong, an outsider, wondered: "Why?"
Ma Jianbin and others were also confused. Yes, why is this
According to this theory, the more cylinders the better, but why does it have to be an odd number? What does odd and even numbers have to do with this engine
Li Zhen said: "This is because multiple cylinders surround the rotor and jointly provide power. So as long as there is an even number of cylinders, there must be an overhead and parallel arrangement in the cylinders. Because the core of the radial engine is that multiple cylinders are arranged parallel to each other. The rotor is spread out, and each cylinder only rotates at a fixed angle."
"For example, if it is a five-cylinder machine, then when the rotor rotates once, it is not that the five cylinders take turns to make it rotate once. Instead, every time it rotates, five cylinders participate in the work. The first cylinder rotates the rotor Turn it one-fifth, and the second one makes it turn two-fifths. So presumably.”
"So, if the number of cylinders is an even number, then there will definitely be an overlapping phenomenon, which will cause the pistons in the two cylinders to move synchronously. The two cylinders will jointly participate in the fifth. In this way, Its vibration will definitely be huge. This kind of vibration will be undulating and will be fatal."
"So, the radial reciprocating engine must use an odd number of cylinders. For example, five cylinders, seven cylinders, nine cylinders. Double rows of five cylinders, double rows of seven cylinders. Or three rows of five cylinders, three rows of seven cylinders."
“…”
Everyone was mesmerized when they heard it, and there were constant sounds of sucking in air-conditioning.
Ma Jianbin drew a rough sketch on paper, drew a rotor, and drew the average emissions of ten cylinders. As a result, when I measured it with a ruler, three or four groups were actually parallel. Three or four groups all had top-to-top phenomena.
He took a breath, as expected, everything is knowledge. Who would have thought that there would be such a big difference between just an odd number and an even number.
It's just a numerical concept. But the story behind it is not that simple.
Liu Jinghong, a layman, was also sweating profusely.
This is science.
How does Li Zhen’s head grow
If he hadn't mentioned these problems before, then the Motor Vehicle Institute would have some obsessive-compulsive disorder. In order to pursue greater power, he might have to get you an engine with more than 20 or more than 30 cylinders. As a result, it was actually of no use.
(End of chapter)