V-84M battle tank engine

When the crankshaft rotates, the piston, moving in the cylinder from TDC (Top Dead Centre) to BDC (Bottom Dead Centre) (180 ° in the angle of rotation of the crankshaft), increases the volume and creates a vacuum in the cylinder. At this time, the intake valves are open and air enters the cylinders. The air pressure in the cylinder at the end of the intake stroke due to resistances (mainly in the air cleaner and intake valves) does not reach atmospheric pressure, especially at high engine speeds. The driven centrifugal supercharger of the engine not only compensates for the pressure drop due to resistance, but also creates excess pressure (above atmospheric pressure) over the entire operating frequency range. The V-46 battle tank engine has an overpressure of 0.82 kgf / cm at an air temperature of 128 ° C.

For better cylinder filling, the intake valves open 35 ° before TDC and close after passing piston BDC (33 ° after BDC), i.e. at the beginning of the compression stroke.

In the compression stroke, the piston moves from BDC to TDC with the intake and exhaust valves closed and the air in the cylinder is compressed (compression ratio 14). A high compression ratio is necessary to obtain high pressure and high temperature of the air in the cylinder, which ensure self-ignition of the injected fuel. The air pressure in the cylinder at the end of compression reaches 66 kgf / cm², and the temperature is 760 ° C.

At the end of the stroke, when the piston has not yet reached TDC by 33 ° ± 0.5 °; fuel is injected into the cylinder, the fuel supplied to the combustion chamber in atomized form, due to the high temperature of the compressed air, quickly heats up and ignites spontaneously.

The gas pressure in the cylinder rises sharply to 105 kgf / cm², and their temperature reaches 1780 ° C.

As a result of the expansion of gases and their pressure on the piston, the latter moves from TDC to BDC and, acting through the connecting rod on the crank, drives the crankshaft into rotation. When the piston moves to BDC, the volume of gases increases, and their pressure and temperature decrease. When the piston approaches the BDC, the intake valves open.

The gas pressure drops to 5.12 kgf / cm² and the temperature drops to 825 ° C.

The piston moves from BDC to TDC; combustion products are removed through the open intake valves. The pressure in the cylinder decreases, exceeding the pressure in the exhaust manifold by 0.05-0.15 kgf / cm² at the end of the stroke.

To accelerate the release of gases from the cylinder at the exhaust stroke and the fastest decrease in the pressure of the gases acting on the piston when it moves from BDC to TDC, the exhaust valves open to BDC in the expansion stroke.

To improve the cleaning of the cylinder from exhaust gases, the exhaust valves are closed after TDC.

At the end of the exhaust stroke and at the beginning of the intake stroke, the intake and exhaust valves are simultaneously open. This period is called valve overlap. On the V-46 engine, the overlap is. 75 ° crankshaft rotation.

During this period, due to the presence of excess pressure. The combustion chamber is purged with air in the intake manifold. As a result of blowing, the cleaning of the cylinder from exhaust gases is improved and the valves, piston and nozzle atomizer body are cooled by air, which increases the reliability of these parts and increases the coefficient of filling the cylinders with air.

Forced filling of the cylinders with air, an increase in its density in the intake manifold due to pressurization, and an increase in the portion of injected fuel (cyclic feed) made it possible to significantly increase the power of the B-46 engine compared to the B-2 type engine (naturally aspirated).