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3.
6
CARBURETOR
57
3. 6
Carburetor
A.
Construction
The carburetor gasifies the fuel, provides mixture
with air, and supplies the mixture to the
engine.
To the
model
450,
the carburetor
,
called "CV
(Constant
Vacuum)
Carburetor"
with
which
the
venturi
area
is automatically
changed
by
inhal
ing negative pressure.
Wi th this CV
carburetor,
the
primary
and secondary venturi relation
beco:nes
very smooth, and for a w ide speed
range,
high
output, acceleration,
and economy can be main-
tained.
Further,
one
carburetor
is
provided indivi-
dually to
one
cylinder and there is no air admission
interference
;
thus, the
mixture
flow
is
smooth.
In
addit ion, the construction is
of
single
body
and
very
simple.
The choke valves
of
both left
and
right
carburetors are interlocked
.
(Fig. 3. 1 20)
(V ENTURI)
The
portion where
.the
gas
flow route
is
squeezed
and
becomes
thin is called "venturi".
The
gas
flow
in the
venturi portion
becomes faster than !he
other
port
ion,
and inter-molecular clearance is
accomplish-
ed ; the pressure is lowered in that
portion
(Fig.
3.
121 ).
Accordingly,
if gasoline outlet in the
venturi
portion, the
sucking
is effectively
performed, and
gasified
just
like an atomizer.
This is the principle
of
the carburetor;
however, actually, air bleed is
provided to improve the
gassification.
(AIR BLEED
)
Wlien sucking water
through
a straw
as
shown
in
fig. 3. 122
a
,
if the · mouth is left,
the water
returns to
the
cup.
If
on opening is provided in
the middle
of
the
straw in
be
tw
een the mouth and
water
level as
shown
in Fig. 3.
122,
bubbles are
simultaneously
sucked,
but
water
does not return
even if the mouth is left from the
straw
due to
the bubbles.
Further, the
opening
is provided
b~low
the water level as shown in
Fig. 3.
122
c,
the bubbles become finer.
This is the principle of
the air bleed.
Gasoline coming out to
the
jet is
not returned but held in the position higher than
t~e float chamber oil level, and simultaneously, it
is
made to bubble ; thus, it is very convenient to
gosify.
Fig
.
3. 120
Constant-pressure
single-bod
y
compound
car
bu-
retor
(D
Left side
carburetor
®
Right side carburetor
Jt__JLJL
....
...
Fig. 3
.
121
Venturi
(al
(b)
Fig. 3. 122
Air bleed principal
(c)
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