valve
@Dieselag
Soupape is a French word that is used in our language in the same original form. The exact meaning of it is valve. But its common meaning is one of the engine parts that is placed on the engine cylinder and controls the intake of air and exhaust of smoke.
overview
Valves follow a certain order to open and close. As you know, combustion engines must be able to burn fuel to produce power, and they do this in the engine cylinder. And obviously, three things are needed to perform the act of burning. Fuel, heat and oxygen.
Therefore, every engine (cylinders of the engine) must be in contact with the outside air so that they can receive the oxygen of the air and return the combustion gases (which are mainly water and carbon dioxide) to the air after combustion.
@DieselG
On the other hand, since the power generation in the engine is such that first the gas entered must be condensed and after compression and explosion, the energy of the gas molecules is converted into the kinetic movement of the piston, it is necessary that the environment for this activity (cylinder) is completely closed and The outside has no connection. Therefore, valves are used to disconnect or connect the connection between the cylinder and the outside environment at appropriate times.
Types of valves
Air (inlet or breathing) valve: It is slightly larger in size than the smoke valve and operates at a lower temperature.
Smoke valve (exit or discharge): due to constant contact with hot gases from combustion, it has a higher temperature. And of course it is smaller in terms of size.
Timing of valves
@DieselG
Adjusting the opening or closing times of the valves is done by a piece called the camshaft. This rod, according to the structure and shape of the protrusions on it (cams), determines when the valves should be opened and then closed. It also determines how long the valves should remain closed. As mentioned, the opening and closing of the valves must be completely synchronized with the up and down movement of the piston in the cylinder.
To ensure this coordination in the engine building, the camshafts are kept in constant and constant contact with the crankshaft.
Valve actuation system
There are different parts for starting and opening the valves in different engines depending on the type and structure of those engines. But in general, the parts needed to open and close the valves correctly are the camshaft, lifter, push rod, valve stem, valve finger and valve springs. Of course, the location and arrangement of valves is effective in the presence or absence of these parts.
Construction materials and valve compounds
Since the valves are exposed to a lot of heat and work at a high speed, they are under considerable pressure and wear. It is obvious that the combustion exhaust valve is hotter than the breathing valve. In fact, when the engine is under load, its temperature may rise so much that the valve turns a dull red color.
In order to resist breaking, rusting, warping and fast wear, discharge valves are made of a special steel alloy that has a relatively large amount of chromium, nickel, silicon and a smaller amount of other metals. Breather valves run much cooler than smoke valves. Therefore, they are less prone to burning, rusting and wear.
Diesel J. Engineering channel
@DieselG
This post is written by Diesel_g