Subaru ER12 - 7-3 Breather System

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7-3 BREATHER SYSTEM
The Breather system functions to decrease for inside pressure of crankcase (in the case of four-stroke
engines) The pressure becomes highly more than the outside atmospheric pressure from reasons as
follows; Piston Comes down, Leak of combustion gases from piston rings, Expansion of internal air by
increase of temperature, Steam of lubrication oil
Breather system prevents for oil leakage from the oil seals of the rotation parts and/or matching surface
of the crankcase and the main bearing cover and so on
Breather system is consisted of labyrinthine passage structure and leaf valves, and separates the
increased pressure which from lubrication oil and gas * in the crankcase The oil is returned in the
crankcase and the gas to the air cleaner to reduce the pressure
(* Blow by gas: Non-combustion gases including the air pollution element which cannot release to
atmosphere It is returned to the air cleaner and non-combustion gases burn again)
In rammer engines, a breather system is required complicated structure to separate oil and gas, reason
why heavy vibration of up-and-down movement compared with stationary engines
Therefore, the ER12 rammer engine is adopted the design which overcame such a difficulty and becomes
the high-performance with compact
BREATHER
SYSTEM
LEAF VALVE
(OIL)
OIL and GAS
GAS
OIL
LEAF VALVE
OIL SHELTER
PLATE
OIL to CRANKCASE
PASSAGE (I.D.3)
AIR CLEANER
COMBUSTION
CRANK CASE
OIL SHELTER
PLATE
GAS to
AIR CLEANER
A
C
B
PASSAGE
(I.D.8)
GAS and OIL
B
A
C
BREATHER SYSTEM
(for separating to oil and gas.)