What are the two types of crankcase ventilation methods?
2 Answers
Crankcase ventilation includes natural ventilation and forced ventilation. Modern gasoline engines commonly adopt forced crankcase ventilation, also known as the PCV system. Here are more related details: 1. Natural ventilation: This method involves installing a ventilation pipe on the crankcase, equipped with an air filter screen. When the pressure inside the crankcase increases, gases leaking into the crankcase are discharged through the ventilation pipe. 2. Forced ventilation: This method directs the mixture in the crankcase to an appropriate position in the intake pipe through a connecting pipe, allowing it to return to the cylinder for re-combustion. This not only reduces exhaust pollution but also improves the engine's fuel efficiency. Gasoline engines for vehicles all adopt forced ventilation, and diesel engines for vehicles are gradually adopting it as well. Forced ventilation can be divided into open and closed types. The open forced crankcase ventilation device, when the engine is at full load and low speed, produces a large amount of blow-by gas, but the flow control valve opening decreases. Excessive blow-by mixture will dissipate into the atmosphere through the open ventilation cover, with a purification rate of only about 75%. The closed forced crankcase ventilation device can fully control crankcase emissions, achieve complete crankcase ventilation, prevent the accumulation of sludge and other harmful substances, and reduce engine faults and wear. The closed forced crankcase ventilation device is a necessary design for gasoline engines to meet emission regulations.
When it comes to crankcase ventilation, I remember there are two types: open and closed. The open type directly vents the crankcase to the atmosphere, like in older cars, where gases escape but it's prone to oil leaks, making the engine compartment messy. The closed type, on the other hand, uses a PCV valve system to suck the gases back into the engine for combustion, which is more environmentally friendly and reduces pollutants. I often check these valves because if they get clogged, it can cause rough idling or increased fuel consumption, so regular maintenance is crucial. When modifying, don’t tamper with the pipes randomly; keeping the ventilation smooth can extend engine life and save the hassle of disassembly and cleaning. Nowadays, closed systems dominate in new cars, and the design of older systems has been simplified a lot.
