The development history of heat engine;
Since the piston internal combustion engine came out in the 1960s, it has been a relatively perfect machine through continuous improvement and development. It is widely used because of its high thermal efficiency, wide range of power and speed, convenient matching and good maneuverability. All kinds of cars, tractors, agricultural machinery, construction machinery, small mobile power stations and chariots around the world are powered by internal combustion engines.
Marine merchant ships, inland river ships and conventional ships, as well as some small aircraft are also propelled by internal combustion engines. The number of internal combustion engines ranks first in the world's power machinery and occupies a very important position in human activities.
Heat engine efficiency:
In the working process of the heat engine, the heat released by the fuel burning in the heater (high temperature heat source) is not completely absorbed by the working medium (working medium), only a part of the heat obtained by the working medium from the heater is converted into mechanical work, and the rest is discharged with the working medium and transferred to the condenser (low temperature heat source).
Part of the mechanical work done by the working medium is lost by overcoming the friction of the parts. According to the working characteristics of the heat engine, the utilization and loss of heat in the heat engine are explained below.
Composition of internal combustion engine:
Cylinder:
It is a cylindrical metal part. The sealed cylinder is the source to realize the working cycle and generate power. Each cylinder with a cylinder liner is installed in the machine body, and its top end is closed with a cylinder cover.
The piston can reciprocate in the cylinder liner to seal the cylinder from the lower part of the cylinder, thus forming a sealed space with regular volume change. Fuel burns in this space, and the generated gas power drives the piston to move.
Crankshaft:
The function of the crankshaft is to convert the reciprocating motion of the piston into rotary motion, and transfer the work done by the expansion stroke through the flywheel installed at the rear end of the crankshaft. The flywheel can store energy, so that the other strokes of the piston work normally and the crankshaft rotates at a constant speed. In order to balance the inertia force and reduce the vibration of the internal combustion engine, a counterweight is also properly installed on the crank of the crankshaft.