Basic working principle of the engine
First, the basic theory
Gasoline engines convert the energy of gasoline into kinetic energy to drive a car. The easiest way is to get kinetic energy by burning gasoline inside the engine. Therefore, the automobile engine is an internal combustion engine - combustion occurs inside the engine.
There are two points to note:
1. There are other types of internal combustion engines, such as diesel engines and gas turbines, each with its own advantages and disadvantages.
2. There are also external combustion engines. Steam engines used in early trains and ships are typical external combustion engines. Fuel (coal, wood, oil) is burned outside the engine to produce steam, which then enters the interior of the engine to generate power. The efficiency of an internal combustion engine is much higher than that of an external combustion engine, and it is much smaller than that of an external combustion engine of the same power. Therefore, modern cars do not use steam engines.
In contrast, internal combustion engines are more efficient than external combustion engines, cheaper than gas turbines, and easier to add fuel than electric vehicles. These advantages make most modern cars use reciprocating internal combustion engines.
Second, combustion is the key
The engine of a car generally uses 4 strokes. (Mazda's rotor engine is not discussed here, the car pictorial has been introduced)
The four strokes are: intake, compression, combustion, and exhaust. After completing these 4 processes, the engine completes one cycle (2 laps).
Understand 4 strokes
The piston, which is connected by a piston rod and a crankshaft, is as follows:
1. The piston starts at the top, the intake valve opens, the piston moves down, and the oil and gas mixture is drawn in.
2. The piston moves to the top to compress the oil and gas mixture, making the explosion more powerful.
3. When the piston reaches the top, the spark plug emits a spark to ignite the oil and gas mixture, and the explosion causes the piston to move downward again.
4. The piston reaches the bottom, the exhaust valve opens, the piston moves upward, and the exhaust gas is exhausted from the cylinder by the exhaust pipe.
Note: The resulting motion of the internal combustion engine is rotating, and the linear reciprocating motion of the piston is ultimately converted into rotation by the crankshaft to drive the car tire.
Third, the number of cylinders
The core component of the engine is the cylinder, and the piston reciprocates in the cylinder. The above describes the movement process of a single cylinder, while the actual application of the engine has multiple cylinders (4 cylinders, 6 cylinders, 8 cylinders are more common) ). We usually classify the engine by the arrangement of the cylinders: inline, V or horizontally opposite (of course there is also the Volkswagen Group W, which is actually two V components). See below
Horizontally opposed 4 cylinders
The different arrangements make the engine have its own advantages and disadvantages in terms of smoothness, manufacturing cost and appearance, and are equipped in the corresponding car.
Fourth, displacement
The compression and combustion of the mixture is carried out in the combustion chamber. The piston reciprocates. You can see the change in the volume of the combustion chamber. The difference between the maximum and minimum values is the displacement, measured in liters (L) or milliliters (CC). . The displacement of a car is generally between 1.5L and 4.0L. The displacement per cylinder is 0.5L, and the displacement of the 4-cylinder is 2.0L. If the V-arrangement is 6 cylinders, it is V6 3.0 liters. In general, displacement represents the magnitude of engine power.
So increasing the number of cylinders or increasing the volume of each cylinder's combustion chamber allows for more power.
Five, the rest of the engine
Camshaft controls the opening and closing of the intake and exhaust valves
Spark plug The spark plug emits a spark to ignite the oil and gas mixture, causing an explosion to occur. Sparks must be released at the appropriate time.
Valves The intake and exhaust valves are opened at appropriate times to draw in the oil and gas mixture and exhaust the exhaust. In compression and
When burning, both valves are closed to ensure the seal of the combustion chamber.
The piston ring seals the cylinder wall and the piston:
1. Prevents oil and gas mixture and exhaust gas from leaking into the oil tank during compression and combustion.
2. Prevent lubricant from entering the cylinder for combustion.
Most of the "burning oil" cars are because the engine is too old: the piston ring is no longer sealed (the exhaust pipe is blue smoke)
The piston rod connects the piston ring and the crankshaft so that the piston and crankshaft maintain their respective motion.
The lubricating oil tank surrounds the crankshaft and has a considerable amount of oil inside.
