Cylinder working volume
The engine is an energy conversion mechanism that converts the heat generated by the combustion of fuel into mechanical energy. In this process, the combustible mixture is required to be burned on fire, and the expansion pushes the piston down to achieve external work. The volume swept between the top dead center and the bottom dead center during the movement of the piston, that is, the volume swept by one stroke of the piston is called the working volume of the cylinder.
Inside the cylinder is the piston reciprocating to provide power to the car. The displacement is the volume that the piston sweeps from the top dead center to the bottom dead center during this process, that is, the effective volume. The cylinder volume refers to the total volume of the cylinder, which is equal to the sum of the cylinder working volume and the combustion chamber volume.
The working volume of the engine is equal to the cylinder volume multiplied by the number of cylinders. Engine displacement is one of the most important structural parameters. It is more representative of the size of the engine than the bore and number of cylinders. Many of the engine's specifications are closely related to the displacement. The unit of engine displacement is generally liter, and the displacement of household passenger cars is mostly between 1.4-2.0 liters.
The compression ratio of a typical car is about 10:1. It can be understood that 10 is the cylinder volume, and 1 is the invalid volume, and the difference 9 is the displacement. If we compress the fuel to zero volume, then the volume is equal to the displacement, and this is impossible.