What is the working principle of a gasoline engine?
3 Answers
Gasoline engine works by burning fuel in the cylinder to generate kinetic energy, which drives the piston inside the engine cylinder to move back and forth. This movement drives the connecting rod attached to the piston and the crankshaft connected to the connecting rod, performing a reciprocating circular motion around the center of the crankshaft, thereby outputting power. The gasoline engine mainly consists of the crankshaft connecting rod mechanism, valve mechanism, driving mechanism, fuel supply system, and cooling system. The function of the crankshaft connecting rod mechanism is to convert the linear motion generated by the expansion of the gas during the power stroke into the rotational motion of the crankshaft. The function of the valve mechanism is to ensure that the valves open and close at certain positions of the piston, allowing the combustible mixture to enter the cylinder and the exhaust gas to be expelled from the cylinder. The function of the fuel supply system is to form a combustible mixture of air and gasoline, and to distribute the mixture evenly to each cylinder according to the engine load, while expelling the burned exhaust gas from the cylinder. The function of the cooling system is to cool the cylinder block, cylinder head, valves, and piston components that are in contact with high-temperature gas in the engine, ensuring that these parts are not damaged due to overheating and making the engine work reliably.
I'm particularly fascinated by car engines, and the working principle of gasoline engines is essentially powered by a cyclic process. The engine core consists of four strokes: the first is the intake stroke, where the piston moves downward, drawing a mixture of air and gasoline into the cylinder through the intake valve; next is the compression stroke, where the piston compresses this mixture upward, making it denser and hotter; then comes the power stroke, where the spark plug ignites the mixture, causing an instantaneous explosion that pushes the piston downward, generating power to drive the crankshaft; finally, the exhaust stroke occurs, with the piston pushing the burned exhaust gases out. This four-step cycle repeats continuously, allowing the engine to turn and drive the wheels forward. The key is that gasoline, as a fuel, is easy to ignite, and the control system precisely regulates the fuel injection amount and ignition timing to ensure efficiency and stability. Modern engines incorporate turbocharging or direct injection technology to enhance performance, but the core remains unchanged. I often ponder this design—simple yet ingenious—reducing vibration and pollution, making driving smoother and safer.
Having driven gasoline cars for over twenty years, I've found the working principle of the engine to be quite simple and intuitive. When you start the car, the pistons inside the engine move up and down: first, they move downward to draw in a mixture of air and gasoline, then they compress it upward, making it hot and tightly packed. The spark plug ignites the mixture, causing an explosion that pushes the piston down, generating power. Finally, the piston moves back up to expel the exhaust gases. The entire process is coordinated by the camshaft, which controls the opening and closing of the valves, while the crankshaft converts the piston's linear motion into rotational force. When you press the accelerator, more fuel is injected, leading to a stronger explosion and faster acceleration. At idle, the cycle frequency is lower, saving fuel. Maintenance is crucial—for example, regularly replacing spark plugs to prevent misfires and ensuring a proper mixture for stable operation. Changes in engine sound while driving can hint at potential issues, and early inspections can prevent breakdowns.
