Filter
Top Products
4-15
COMBUSTION
SYSTEM
For
lower fuel consumption and easy starting of the engine,
the direct injection system is adopted in the combusition
chamber.
4-15-1
FORMING
of
COMBUSTION GAS
and
COMBUS-
TION
/INTAKE
VALVE
INTAKE
PORT
SWIRL
CYLINDER
PISTON
Fig.
13
SWIRL
(Inspiring swirl)
In order to promote mixing injected fuel and air under
the direct injection system, swirl flow is utilized for
good
Combustion. Swirl is spiral flow
of
air generated
in
the cylinder during inspiring stroke, and it decreases
during compressing stroke but it still remains and pro-
motes mixing of fuel and
air
toward ignition timing.
Spiral flow
of
air
(swirl)
is generated by the shape of
intake port, which
is
called helical port
or
spiral port.
Tail
end of intake port, i.e. upper part of intake valve
seat, is made in the spiral form; and while the inspired
air
is
passing through this part, swirl
is
generated
around the intake valve. Thus, intake port plays an
im-
portant role in generating
swirl.
(See Fig. 13.)
SQUISH
(Squished air flow)
In the piston, combustion chamber (dish type com-
bustion chamber) is formed. When the piston comes
up to
TDC
(top dead center), air in the gaps is squished
in
the combustion chamber and air flow is generated,
which is called “squish.” (See Fig.
14.)
FORMING
of
COMBUSTION
GAS
and
COMBUSTION
For igniting quickly the fuel injected from the nozzle, it is essential to atomize very fine
oil
particles
for
distributing
evenly in the combustion chamber.
For
ths purpose, fuel should be injected through hole type nozzle by very
high
pressure, i. e.
195
kg/cm2. The fue!, thus injected,
is
mixed with
air
by
the flow of swirl and squish while piston
is
Coming Up. Accompanying crimb
of
the piston, combustion gas compressed further and finally it automatically begins
igniting and while piston is going down, “squish” functions and promotes combustion.
Fig.
14
-
10
-