How a 4 Stroke Diesel Engine Works. As with gasoline motors, there are 4 stroke and 2 stroke diesel engines, in its application to the automotive/vehicle sector, 4 stroke diesel engines are mostly used.
In a 4 stroke diesel engine, the intake and exhaust valves are used to control the gas intake and exhaust process by opening and closing the intake and exhaust ports. The difference is, if on a gasoline engine, air and fuel enter together through the intake manifold and suction valve, while in a diesel engine, only air (gas) enters the combustion chamber through the intake and suction valves.
The second difference, if the gasoline engine combustion is obtained from the sparks on the spark plug, in the diesel engine this is not the case, but with the heat generated during the air compression stroke, then the injector nozzle sprays fuel that has been atomized (atomized) so that it easily happens. burning. More specifically, consider the following:
Diesel engine
In a diesel engine, fuel is injected by an injector nozzle into a cylinder in which hot air is available due to the compression stroke. This causes the fuel to burn and combustion occurs which results in a work stroke. The air entering the cylinder is not regulated as in a gasoline engine.
The intake of air is only based on the intake of the piston. So, in a diesel engine, the engine output is regulated or determined by the amount of fuel injected. To determine the amount of diesel engine output depends on two things, namely (1) the amount of compression pressure and (2) the amount and time of injection of the right fuel.
Gasoline Engine
The output of the gasoline engine is controlled by the throttle valve on the carburetor by adjusting the amount of air and gasoline mixture that enters the cylinder. To determine the magnitude of the output of a gasoline engine depends on three things, as follows;
a) The ratio of air and fuel entering the cylinder.
b) The amount of ignition and the timing of ignition.
c) The amount of compression .
The following is the working principle of a 4 stroke diesel engine
What needs to be considered is that there are several types of combustion chambers in diesel engines, including diesel engines that use the main combustion chamber plus an additional combustion chamber, but there are also diesel engines that use only the main combustion chamber or are called direct injection chambers. . Well, below is how a diesel engine works that uses a direct combustion chamber (direct injection). For those who use additional combustion space, maybe I will share next time. Immediately, here is how a 4-stroke diesel engine works:
Suction Step
During the first step, namely the suction stroke, the piston moves downwards (from TDC to BDC) thus creating a vacuum in the cylinder, this vacuum makes air sucked in and into the cylinder. At this time the intake valve opens and the exhaust valve closes.
Compression Step
In the second step, also known as the compression stroke, the air that has entered the cylinder will be pressed by the upward moving piston (TDC). The compression ratio in diesel motors ranges from 14: 1 to 24: 1. As a result of this compression process the air becomes hot and the temperature can reach around 900 °C. At this stage both valves are in the closed position.
Burning Step.
At the end of the compression stroke, the injector nozzle sprays high pressure fuel in the form of a mist into the combustion chamber and then together with the air is burned by the heat generated in the compression stroke. Followed by delayed combustion, at the beginning of the final effort step the formation of fuel atoms will burn as a result of direct combustion and burn almost all of the fuel. As a result, the cylinder heat increases and the cylinder pressure increases. The power generated by combustion is transmitted to the piston. The piston is pushed down (TDC) and the combustion power is converted into mechanical power. At this time both words are also in the closed position.
Discard Step
In this step the piston will move up to TDC and push the remaining exhaust gas out through the exhaust valve which is already open, at the end of the exhaust stroke fresh air enters and helps push the remaining used gas out and the next work process will begin. In this step the exhaust valve opens and the intake valve closes.
