- Why does the engine provide continuous power?
The reason why the engine can provide power continuously is due to the orderly cycle of the four strokes of intake, compression, power and exhaust in the cylinder.
In the intake stroke, when the piston moves from the top dead center to the bottom dead center in the cylinder, the intake valve opens and the exhaust valve closes, and fresh air and gasoline mixture are sucked into the cylinder. In the compression stroke, the intake and exhaust valves are closed, and the piston moves from the bottom dead center to the top dead center, compressing the mixed gas to the top of the cylinder to increase the temperature of the mixed gas and prepare for the power stroke. In the power stroke, the spark plug ignites the compressed gas, and the mixed gas "explodes" in the cylinder to generate huge pressure, pushing the piston from the top dead center to the bottom dead center, and driving the crankshaft to rotate through the connecting rod. In the exhaust stroke, the piston moves from the bottom dead center to the top dead center. At this time, the intake valve is closed and the exhaust valve is opened, and the exhaust gas after combustion is discharged out of the cylinder through the exhaust manifold.
- Engine power comes from explosion
The engine can generate power from the "explosive force" in the cylinder. In the sealed cylinder combustion chamber, the spark plug instantly ignites a certain proportion of gasoline and air mixture at the right time, which will generate a huge explosive force. The top of the combustion chamber is fixed, and the huge pressure forces the piston to move downward, pushing the crankshaft through the connecting rod, and then transmitting power to the drive wheels through a series of mechanisms, ultimately driving the car.
- Spark plugs are masters of "detonation"
If you want the "explosion" in the cylinder to be more powerful, timely ignition is very important, and the spark plug in the cylinder plays the role of "detonation". In fact, the principle of spark plug ignition is a bit similar to lightning. The spark plug head has a central electrode and a side electrode (equivalent to two clouds of ions with opposite polarity), and there is a very small gap between the two electrodes (called the ignition gap). When powered on, it can generate an electric spark of more than 10,000 volts, which can instantly "detonate" the mixed gas in the cylinder.
- The intake valve is larger than the exhaust valve
In order to continuously "explode" in the cylinder, new fuel must be continuously input and exhaust gas must be discharged in time. The intake and exhaust valves play an important role in this process. The intake and exhaust valves are controlled by cams, and the two actions of "opening" and "closing" are performed in a timely manner. Why are the intake valves larger than the exhaust valves? Because generally the intake is sucked in by vacuum, and the exhaust is squeezed to push the exhaust gas out, so exhaust is relatively easier than intake. In order to obtain more fresh air to participate in combustion, the intake valve needs to be made larger to obtain more intake air.
- The number of valves should not be too many
If the engine has multiple valves, the intake volume is large and the exhaust is clean at high speed, and the engine performance is better (similar to a movie theater, if there are many entrances, it is much more convenient to get in and out). However, the multi-valve design is more complicated, especially the valve drive method, combustion chamber structure and spark plug position all need to be precisely arranged, so the production process requirements are high, the manufacturing cost is naturally high, and the later maintenance is also difficult. Therefore, the number of valves should not be too many. Common engines have 4 valves per cylinder (2 in and 2 out).
Edited by Asiautos Auto Part
