The crankcase ventilation system: structure, types, working principle

Currently, despite the rapid development of technology, to create a completely sealed friction of the parts — the cylinder and the piston ring is not possible. Therefore, in the internal combustion engine over time during the operation of combustion products accumulate.

In the sump of crankcase gases pass through the piston rings, which are adjacent to the cylinders loose. The result is worse than the heat is removed, reducing the lifetime lubricating fluid and formed excessive pressure on all block seals. The crankcase ventilation system prevents excessive crankcase pressure.

Development device

At the beginning of the mechanism is as follows: from the case just output tube, producing gases into the atmosphere and polluting it. But the norms for emission of gases from vehicles was seriously tightened. Therefore, the crankcase ventilation system had to be developed by manufacturers.

The Principle of operation of mechanism

In the form in which the system currently known, gases are not simply emitted into the atmosphere. They are sent to the motor by means of the derived tube from the crankcase, the other end of which is connected to the intake manifold. From there the gas is directed into the combustion chamber. At the time of the outbreak some of them burned and the other part is discharged through the exhaust mechanism. Only a small fraction of these gases back into the crankcase. So the process occurs without interruption.

Types of recirculation Carter

There are two types of systems:

• Public;
• Closed.

In the first case, as described in the beginning of the article, just gases are discharged into the atmosphere. In the second they are sucked into the intake pipeline. A closed crankcase ventilation system: VAZ and Lada, BMW and Mercedes, the Japanese and Americans is mainly used at present.

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In Addition, closed systems are available with variable or constant flow. The first type is more accurately able to adjust the recirculation sump. It varies depending on the number of incoming gases.

Device

At the top is the oil separator of the crankcase ventilation system and inside it — an oil deflector. Its task is the release of gases from the oil particles. The oil separator of the crankcase ventilation system has the exit pipe. During normal operation, the motor in the crankcase should always occur a certain negative pressure. The valve can operate in three modes.

Forced crankcase ventilation system: valve

Let us briefly Consider all three of these options.

1. After the chock is formed in a low pressure from 500 to 700 mbar. The crankcase ventilation system, such a regime does not stand up. And the piston, under the action of vacuum closes the valve.
2. If the throttle is opened completely, the pressure there equal to atmospheric or even higher. Upon reaching the 500-700 mbar piston closes the valve for the passage of gases.
3. In the middle position, provided the normal pressure of the piston.

If valve operation is causing issues, its serviceability is easy to check. On idle on the neck, where filled with oil, placed a sheet of paper. If it is lowered and raised together with the diaphragm movement, the valve is serviceable.

The Normal functioning you can test another way. In the idle circulation, remove the vent hose and close it with your finger: it should feel suction.

Pressure Reducing valve

If the motor operates at high speeds, the intake manifold pressure appears, which is of equal importance with atmospheric or greater. In this case, Carter gets more gas. If the inlet of a turbocharger, the vacuum will be too large and should be trimmed.

This provides a pressure-reducing valve that is triggered in the intake manifold when opening the damper. Mechanism consisting of a membrane and a spring is inserted in a plastic housing, which has inlet and outlet fittings.

Pressure reducing valve

Under normal vacuum pressure the spring is not loaded. When this membrane is raised and the gases are passed freely.

Under reduced pressure, the diaphragm descends and closes the exit, overcoming the action of the spring. The gases then move through a workaround — the canal orifice.

Unfortunately, acting positively on the one hand, the crankcase ventilation system engine creates a problem with other. Coming out of the pan, capture gases and particles grease, thus contaminating the intake system. In addition, they are deposited on the surfaces of the output channels and the details of the recirculating valve. This leads to a narrowing of the channels and may cause malfunction of the injection. If the diaphragm is jammed, the oil consumption will increase. Then you have to change the valve.

Also we must not forget about other important details and time to change the hose of the crankcase ventilation system — usually this is done together with recirculation valves. Inotherwise, it cracks and breaks.

To prevent expensive repairs, it is necessary to pay attention to specific spots on the seals of the engine, the increased consumption of fuel and lubricating fluid and unstable operation of the motor. If the time to drive to the service center, the problem will be solved in the Bud before she managed to inflict significant damage to the unit.