AGK system (Oil system)
- ATVpilot
- Jun 16, 2020
- 2 min read
Engine oil is essential for the engine operation.
Purposes of Oil:
Lubrication
Cooling
Cleaning
Protection
Sealing
Hydraulic actuation
Lubrication
Key word: Reduce friction
Less friction; less engine loss within engine
Cooling
Hot engine parts is continuous circulated by engine oil; and the heat will be carried away from the hot section.
Cleaning
Key word: carries contaminants
Oil carries contaminants away, and the contaminant will be filtered and trapped by the oil filter.
Protection
Key word: resist corrosion to metal parts
Oil coating on metal prevents oxidation ( corrosion)
Sealing
Key word: Seals between cylinder wall and piston
Oil provides a better seal between cylinder wall and piston; avoid compressed gases escaping pass the piston ring to crankcase.
(Gas escaping-> losing pressure->losing performance)
Oil properties:
Viscosity -Resistance to flow
The higher Viscosity, the more resistance to flow; in another word, the liquid is thicker and unwilling to flow. High temperature can reduce the oil viscosity.
High ignition point
-Of course, oil has a high flashing point and will not vaporize and ignite easily.
Stability
-Resist chemical reaction(corrosion) and it has to maintain its characteristic over wide range of operating temperature and pressure.
Oil system:
Wet-sump oil system
In a wet-sump system, oil is stored in the collector sump, located at the bottom of the engine. (see item 7)
Oil will be pressurized thru built-in oil pump to oil cooler/ filter(see item 4.) Then, oil will be circulate to different engine parts.
After passing thru the hot parts inside the engine, oil will dip thru the engine and return to the sump.
Keyword: Sump inside the engine
Dry sump oil system
Dry-sump system is very much similar to the wet-sump system, except it has an external tank for store the oil.
It utilize a scavenger pump to extract oil from the engine casing back to the external tank.
This design is commonly find in aerobatic aircraft and aircraft with radial engine.
(Dry sump design eliminate the chances of oil starvation during aerobatic operation.)
For radial engine, it is prone to hydraulic lock. (Hydraulic lock is oil tends to pass thru the oil ring and accumulate in the lower cylinders.) Therefore, Dry- sump system is also found in most radial engine aircraft.
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