I am often asked questions about the blow-by gases of the petrol engine. Namely, what is it? What is the source? Ask a question about the valve (this system), ventilation system and so on. In this article to tell you will not work, because it's just a great material (I will write a few articles), but will try here to begin with — that is, where are the dangers and is it possible to release them into the environment.
THE CONTENT OF THE ARTICLE
- What are crankcase gases?
- Device system
- The recirculation of crankcase gases
- What is the EGR valve blow-by gas?
- Faulty valve, engine
First, it should be noted that these gases it is absolutely normal as any petrol engine, as they are good units and defective (they just manifest themselves a little differently).
What are crankcase gases?
The blow-by gases are gases which are formed during the compression and ignition of air-fuel mixture through the compression rings (on the compression stroke and the ignition stroke) were held in the crankcase. Moreover, some part, even a new engine always gets into the crankcase (usually from 5 to 7%), have worn out units, this percentage is much higher.
Device system
Now let's talk about this in more detail, let's start with the device
So, everyone knows that every internal combustion engine there are only 4 main bars:
Intake – intake valve open, piston going down creates a (low atmosphere in the intake manifold), sucked air / fuel mixture
Compression – the piston goes up, compressing the mixture
Ignition – as the mixture at TDC (top dead center) is ignited by the spark plug, forms a "flame front" that pushes the piston down
The output of the exhaust – exhaust valve opens and is drained worked the gas mixture (pushed the piston in the silencer).
4 stroke engine
For many this is nothing new, it is a conventional 4-stroke engine (or rather his scheme of work).
However, it should be noted that the engine worked on the pistons is the so-called rings, they are generally divided into two types:
Compression. Those that hold the compression (usually two) do not allow the gases get past the piston
Oil. Remove excess oil from the walls (often it is one, is at the bottom of the piston) to prevent breakthrough of grease in the combustion chamber.
However, compression rings, can't 100% exclude the passage of gases into the crankcase. Part still enters, for example, through the locks of the rings, using a loose fit to the walls, with a small deformation (walk) rings during piston operation.
And as I wrote above, the crankcase is about 5 – 7% of the gases from the combustion chamber. Here and air / fuel mixture on the compression stroke of + the exhaust gases after the ignition of the fuel (because the pressure at ignition is huge). BUT if piston, worn out, then the passage may at times increase.
The recirculation of crankcase gases
What to do to break the gas mixture? As a rule, through various channels (for example, where there is a chain), they go up in the valve cover (can directly from the crankcase through hoses to climb up).
Continued in the Part II...