EVAPORATIVE EMISSION CONTROL FOR CARBURETTOR
FIELD OF THE INVENTION
[001] The present invention relates to a system of controlling evaporative emissions
from carburettor.
BACKGROUND
lUU2J It is well known that source of air pollution from vehicles include exhaustive
emissions as well as evaporative emissions. Apart from evaporative emissions from a
fuel tank, evaporative emissions from a carburettor of a vehicle also contribute
substantially to the atmosphere contamination. Fuel loss from the carburettor generally
occurs as a result of evaporation loss of fuel from a carburettor float chamber. · Such
evaporative. loss becomes significantly noticeable when an engine unit of the vehicle is
hot, for example during hot weather condition or due to extended continuous running of
the engine unit. In order to control evaporative emissions, there exists a need for suitable
means to control loss of the evaporated fuel from the carburettor of the vehicle.
SUMMARY
[003] Embodiments of a carburettor of a vehicle are disclosed. In an embodiment, a
carburettor comprises a carburettor body, a float chamber, a drain pipe and a drain tube.
The carburettor body comprises an air intake passage. The float chamber is configured at
a bottom portion of the carburettor body. The drain pipe is for discharging excess fuel in
the float chamber. The drain pipe comprises a first end opening and a second end
opening. The first end opening of the drain. pipe is disposed in the float chamber at a
position higher than a pr~defined normal fuel level in the floar chamber. The second end
opening of the drain pipe is disposed outside of the float chamber for discharging the
excess fuel. The drain tube comprises a first end and a second end. The first end of the
drain tube is connected to the second end opening of the drain pipe. The drain tube
further comprises at least one condensing provision for facilitating evaporated fuel
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IPO DELHI 02-&9-2015 lS:SS
generated from inside the float chamber to at least partially condense in the at least one
condensing provision.
[004] In an embodiment, the at least one condensing provision comprises one or
more curved portions of the drain tube. Each curved portion of the drain tube comprises
at least one trough for facilitating condensing of the evaporated fuel to form a condensed
fuel pit. Moreover, the condensed fuel pit cuts a communication between the float
chamber and atmosphere through the drain pipe.
[005] In an embodiment, each of the one or more curved portions of the drain tube
is in form of a loop comprising a loop crest and a loop trough. The loop trough facilitates
condensing of the evaporated fuel. In an embodiment, a vertical level of the loop crest is
lower than a vertical level of the fuel in the float chamber. In an embodiment, each of the
one or more curve.d portions of the drain tube is in form of a sinusoidal configuration. In
an embodiment, the drain tube is mounted to a body frame of the vehicle by a mounting
means.
[006] In another embodiment, a carburettor comprises a carburettor body, a float
chamber and a drain pipe. The carburettor comprises an air intake passage. The float
chamber is configured at a bottom portion of the carburettor body. The drain pipe is for
discharging excess fuel in the float chamber. The drain pipe comprises a first end
opening and a second end opening. The first end opening of the drain pipe is disposed in
the float chamber at a position higher -than a predefined normal fuel level in the float
chamber. The second end opening of the drain pipe is disposed outside of the float
chamber for discharging the excess fuel. Moreover, the drain pipe further comprises at
least one condensing provision for facilitating evaporated fuel generated from inside the
float chamber to at least partially condense in the at least one condensing provisions. The
at least one condensing. provision is configured between the first end opening and the
second end opening within the float chamber.
[007] In an embodiment, the at least one condensing provision comprises one or
more curved portions of the drain pipe. Each curved portion of the drain pipe comprises
at least one trough for facilitating condensing of the evaporated fuel to form a condensed
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IPO DELHI 92-09-2015 16:55
fuel pit. Moreover, the condensed fuel pit cuts a communication between the float
chamber and atmosphere through the drain pipe. In an embodiment, each of the one or
more curved portions of the drain pipe is in form of a loop comprising a loop crest and a
loop trough. Moreover, the loop trough facilitates condensing of the evaporated fuel.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[008] The invention itself, together with further features and attended advantages,
will become apparent from consirleration of the following Jetailed description, taken in
conjunction with the accompanying drawings. One or more embodiments of the present
invention are now described, by way of example only wherein like reference numerals
represent like elements and in which:
[009] Figure 1 illustrates a side view of a two wheeled vehicle according to an
embodiment of the present invention;
[0010] Figure 2 illustrates a vertical sectional v1ew of a carburettor of the two
wheeled vehicle according to an embodiment of the present invention;
[0011] Figure 3 illustrates a view of the carburettor and drain pipe arrangement(s)
according to an embodiment of the present invention;
[0012] Figure 4 illustrates a view of curved portions of the drain pipe according to
an embodiment of the present invention; and
[0013] Figure 5 illustrates a view of the carburettor and drain pipe arrangement(s)
according to another embodiment of the present invention.
[0014] The drawings referred to in this description are not to be understood as being
drawn to scale except if specifically noted, and such drawings are only exemplary in
nature. The coloured drawings, if provided along with this description are only meant to
make the details of invention clear and have no effect on the scope of the invention.
DETAILED DESCRIPTION
IPO DELH1 92-09-2015
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[0015) While the invention is susceptible to various modifications and alternative
forms, an embodiment thereof has been shown by way of example in lhe drawings and
will be described here below. It should be understood, however that it is not intended to
limit the invention to the particular forms disclosed, but on the contrary, the invention is
to cover all modifications, equivalents, and alternative falling within Lhe spirit and the
scope of the invention.
[0016] The terms "comprises", "comprising", or any other variations thereof, are
intended to cuvt:r a non-exclusive inclusion, such that a setup, device or method that
comprises a list of components or steps does not include only those components or steps
but may include other components or steps not expressly listed or inherent to such setup
or device or method. In other words, one or more elements in a system or apparatus
proceeded by "comprises ... a" does not, without more constraints, preclude the existence
of other elements or additional elements in the system or apparatus.
[0017] For the better understanding of this invention, reference would now be made
to the embodiment illustrated in the accompanying figures and description here below,
further, in the following figures, the same reference· numerals are used to identify the
same components in various views.
[0018] The terms "front I forward", "rear I rearward I backward", "up I upper I top",
"down I lower I lowerward" used herein represents the directions as seen by a vehicle
driver sitting astride and these Clirections are referred by arrows Fr, Rr, U, Lr, in the
drawing figures. Further, "left I leftward", "right I rightward" used herein represents the
directions as seen by a vehicle driver sitting astride.
[0019] Figure 1 illustrates side view of two wheeled vehicle (100) according to an
embodiment of the present invention. The two wheeled vehicle (100) comprises, interalia,
a front fork (121), a head pipe (122), a front fender (172), a front wheel (123), a
headlight (128), a steering handlebar (124), a fuel tank (125), an engine unit (126), an
evaporated fuel collecting device (113), a rear suspension (129), a swing arm (173), a
dress guard (111), a rear wheel (127), a rear fender (116), a taillight assembly (117), and
a seat (130). It may be noted that the two wheeled vehicle (100) is shown to have include
above stated parts, however, those ordinarily skilled in the art would appreciate that the
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IPO DELHI 82-99-2815
two wheeled vehicle (100) includes other parts which may not be relevant for explaining
embodiments of the present invention and hence are not shown and described.
[0020] As depicted in Figure 1, the body frame of the two wheeled vehicle ( 1 00)
comprises a main frame (1 02), the head pipe (122), a pair of seat rail members
comprising a left seat rail member (1 03) and a right seat rail member (not visible in
Figures), a pair of sub-frame members comprising a left sub-frame member (109) and a
right sub-frame member (not visible in Figures), a down frame rhember(l05) and one or
more brackets. The 1uaiu frame (102) comprises a front portion (102a) that extends
obliquely in the rearward and downward direction from the head pipe (122) and a rear
portion (1 02b) changing the direction and thereafter extending further downward. The
pair of seat rails comprising the left seat rail member ( 103) and the right seat rail member
(not visible in drawings) extends from a rear end ofthe front portion (102a) of the main
frame (102). The down frame member .(105) obliquely extends in the downward
direction from the lower portion of the head pipe (122). The left sub-frame member
( 1 09) and the right sub-frame member connect the rear portion ( 1 02b) of the main frame
(102) and the respective seat-rail, for example, the left seat-rail (103) or the right seatrail,
through a bracket.
[0021] As illustrated in Figure 1, the front fork(121) is rotatably attached to the head
pipe (122) enabling free steering. The front fork (121) supports the front wheel (123) at
lower end thereof and the steering handlebar (124) at upper end thereof. A front fender
(172) is provided above to the rear of the front wheel (123) for shielding the operator
from mud.
[0022] The fuel tank ( 125) for storing the fuel is supported by the rear portion ( 1 02b)
of the main frame (102) of the two wheeled vehicle (100) at a position upper than the
engine unit (126). A breather pipe is used for sending the evaporated fuel generated in
the fuel tank (125) to the evaporated fuel collecting device (113). The breather pipe
extends obliquely rearwardly from a position near the fuel cap (not shown in Figures)
and extends further downwardly and then extends from the tunnel plate (not shown in
Figures) ofthe fuel tank (125) to the outside ofthe fuel tank (125).
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IPO DELHI 92-99-2915 15:55
[0023] As illustrated in Figure 1, an air cleaner assembly (not visible in Figures) is
di$posed on the rear side of the engine unit (126) and on the lower side of the seat (130)
and the left seat rail member ( 103) .and the right seat rail member. The air intake pipe
. (not shown in Figures) from an air cle.aner assembly (115) is connected to a rear portion
ofthe cylinder head of the engine unit (126) via a carburettor (112) such that air and fuel
supplied from the fuel tank (125) are mixed by the carburettor (112) and supplied to the
·engine unit (126).
[0024] The left seat rail member (1 03) and the right seat rail member primarily
intended to support the seat (130) for a rider and/or pillion, are disposed above the rear
wheel (127). The dress guard (Ill) is connected to the left seat rail member (103), .and
the dress guard (111) is intended to cover the left side of the rear wheel (127). The rear
wheel (127) is covered from above by the rear fender (116) which is mounted onto the
rear end portions of the left seat rail member (1 03) and the right seat rail member. The
rear wheel suspension section includes the swing arm (173) supporting the rear wheel
(127) and at least one rear suspension (129) attached between the swing arm (173) and
the left seat rail member (1 03) or the right seat rail member. The tail light (11 7) is
mounted on the rear fender (116).
[0025] Figure 2 illustrates a vertical cross section of a carburettor and Figure 3
illustrates a view of the carburettor according to an embodiment of the present invention.
Referring to Figures 2 and 3, a carburettor (200) includes a carburettor body (201)
provided with an air intake passage (203) wherein intake air circulates. The carburettor
further includes a float chamber (202) as a fuel chamber body provided at the bottom
portion of the carburettor body (201). A piston type throttle valve (204) is disposed in the
airintake passage (203) and is movable across the air intake passage (203) in a vertical
direction substantially perpendicular thereto. A compression coil spring (205) biases the
piston type throttle valve (204) in a direction of closing the air intake passage (203).
[0026] The piston type throttle valve (204) is provided for adjusting the amount of
air flowing in the air intake passage (203) and is achieved by controlling the movement
of the piston type throttle valve (204) across the air intake passage (203). The movement
of the piston type throttle valve (204) across the air intake passage (203) is governed by
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IPO DELHI GZ-99-2815 16 55
the actuation of a throttle twist gnp (not shown in Figures) which is operatively
connected through a cable (not shown in Figures) to the piston type throttle valve (204).
The piston type throttle valve (204) is moved (raised or lowered) across the air intake
pa~sage (203) according to the actuation of throttle twist grip. A choke valve (206) for
altering the ratio of fuel and air quantity entering into the engine unit (126) is fixed
upstream of the piston type throttle valve (204) in the air intake passage (203). The
choke. valve (206) is operable. by the operator, and is generally used in cold starting
conditions.
[0027] The carburettor body (201) is formed with a first projecting portion (207)
extending into the float chamber (202). A needle jet (208) and a slow jet (209) are
. housed in the first projecting portion (207), wherein the needle jet (208) and the slow jet
· (209) are placed as dipped in the fuel in the float chamber (202). The needle jet (208) is
held in the tubular first projecting portion (207) by a jet holder (21 0) threadedly engaged
with the first projecting portion (207).
[0028] A needle (212) is mounted at its upper end portion to a bottom wall of the
piston type throttle valve (204) and is inserted in the needle jet (208) such that there is a
gap between the needle jet (208) and the needle (212). The gap between the needle jet
(208) and the needle (212) is modified according to the movement of the piston type
throttle valve (204) thereby changing the amount of fuel supplied to the venturi portion
formed between the piston type throttle valve (204) and wall of the air intake passage
(203).
[0029] The carburettor body (201) further includes a second projecting portion (214)
extending into the float chamber (202) near the peripheral edge of the float chamber
(202) and formed at a position spaced from the first projecting portion (207). The second
projecting portion (214) is formed with ·a fuel induction passage (217) communicating
with a fuel tank (125) (shown in Figure 1). The fuel retained in the float chamber (202)
forms a liquid surface of certain level defined by a float (215) that opens and closes a
fuel in-flow control valve (216). The float (215) is provided in the float chamber (202)
and is pivotably supported by a float pin (218) provided on the carburettor body (201).
The float (215) swings according to the varying fuel level in the float chamber (202).
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IPD DELH~ 92-99-2015 1S:5S
[0030] In case the excess fuel is supplied into the float chamber (202) beyond the
normal fuel value, such an excess rise in fuel level is prevented by providing a drain pipe
(220) having one end opening (e.g, a first end opening 220a) .higher than a predefined
normal fuel level in the float chamber (202) and the other end opening (e.g, a second
end opening 220b) communicating with the outside of the float chamber (202) to
discharge the excess fuel. The drain pipe (220) is positioned within the float chamber
(202) at an appropriate level to prevent fuel from filling the tloat chamber (202) above a
predetermined level. The drain pipe (220) is position~rl hr:'tween the firgt prujecling
portion (207) and the second projecting portion (214) in the float chamber (202) so as to
vertically extend through a bottom wall of the float chamber (202).
[0031] The drain pipe (220) protrudes out of the float chamber (202) by penetrating a
bottom wall surface (202a) of the float chamber (202). An upper end opening (e.g., the
first end opening 220a) of the drain pipe (220) acting as an inflow port, is disposed
within the float chamber (202). The first end opening (220a) is disposed in the float
chamber (202) such that it protrudes above a preset fuel level (e.g., the predefined
normal fuel level in the float chamber (202)). The drain pipe (220) has an end portion
opening outside of the float chamber (202), for example, as shown by the second end
opening (220b ). The second end opening (220b) of the drain pipe (220) penetrates
outside the float chamber (202) and acts as a discharge port. In an embodiment, the drain
pipe (220) protruding out of the float chamber (202) is a metallic body and is connected
to a drain tube (225). In an embodiment, a first end (225a) of the drain tube (225) is
connected to the second end opening (220b) of the drain pipe (220) to receive the
evaporated fuel, and a second end (225b) of the drain tube (225) is open to atmosphere.
[0032] Figure 3 illustrates an air channel (250). The air channel (250) maintains the
atmospheric pressure above the fuel level in the float chamber (202).
[0033] For the purpose of this invention and as depicted in Figure 3, the drain tube
(225) incorporates at least one provision (e.g., a condensing provision) that enables the
evaporated fuel to at least partially condense and form a condensed fuel pit (260). The
condensing provisions may be configured in a variety of ways between the first end
(225a) and the second end (225b). The fuel vapours flowing from the inflow port (e.g.,
IPO DELHI 02-09-2015
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first end opening 220a) enter the lowest point of the drain tube (225) and condenses there
and accumulate to form the condensed fuel pit (260). The condensed fuel pit (260) cuts
the communication between the float chamber (202) and atmosphere through the drain
pipe (220). In an embodiment, the provision for enabling the evaporated fuel to condense
and form the condensed fuel pit (260) is realised in the. form of a curved portion (221) of
the drain tube (225), wherein the curved portion (221) includes at least one trough (222).
The trough (222) defines the lowest point of the curved portion (221) of the drain tube
(225), where the evaporated fuel condense and form the condensed fuel pit (260)
hindering further leakage of the evaporated fuel. The drain pipe (220) for the
incorporation of the curved portion (221) of the drain tube (225) can be done either
inside the float chamber (202) below the inflow port (the first end opening (220a)) of the
drain pipe (220) or outside of the float chamber (202).
[0034] In an embodiment, the. curved portion (221) of the drain tube (225) can be in
the shape of sinusoidal, parabolic, or any other shape as deemed suited to fulfil the
purpose of this invention. In an embodiment as depicted in Figure 3, the curved portion
(221) of the drain tube (225) is in the form of a loop, wherein the loop is provided
outside of the float chamber (202). In another embodiment as depicted in Figure 4, the
curved portion (221) of the drain tube (225) is sinusoidal in shape wherein the curved
portion{221) is provided outside of the float chamber (202).
[0035) As depicted in Figure 3, the curved portion (221) of the drain tube (225) is in
the form of loop wherein the loop has one· crest (223) (e.g., loop crest) and one trough
(222) (e.g., loop trough). The crest (223) defines topmost point of the curved portion
(221) and the trough (222) defines the lowermost point of the curved portion (221). As
per the present invention, the crest (223) is at a height lower than the fuel level in the
float chamber (202).
[0036] In an embodiment, the drain pipe (220) comprises the curved portion (221)
provided within the float chamber (202) or outside the float chamber (202). For instance,
as shown in Figure 5, the drain pipe (220) comprises the curved portion (221) in form of
loop(s) configured inside the float chamber (202).
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IPO DELHI 82-99-2815 16:55
[0037] The drain tube (225) mounting to the vehicle body frame of the two wheeled
vehicle (1 00) is aided by mounting means (not shown in Figures) including dips, hooks
etc. In an embodiment wherein the curved portion·(221) of the drain tube (225) is in the
shape of loop(s), where the loop(s) are clipped together and then mounted to the vehicle
body frame of the two wheeled vehicle (1 00) by mounting means. In another
embodiment wherein the curved portion (221) is provided in sinusoidal shape and the
nodes of sinusoidal c.urved portion arc clipped togelher and then mounted to the vehicle
body frame of the two wheeled vehicle ( 1 00) by mounting m~{lns During the clipping of
nodes of the sinusoidal curved portion, it should be understood that trough(s) (222) are
clipped together. In an embodiment, the clipped portions of loops and nodes of the
sinusoidal curved portion are hanged using hanging means (not shown in Figures)
already integrated to the vehicle body frame.
[0038] It will be known to those skilled in the art that in a conventional arrangement,
a float chamber of a carburettor communicates with the atmosphere through an air
channel and a drain pipe, hence there is formed a circulation path for the atmospheric air.
Hence, in an example of the conventional arrangements, the atmospheric air can enter
through the air channel above the fuel level in the float chamber and can escape out
through the drain pipe. However, those skilled in the art would appreciate that in various
embodiments of in the present invention, when the condensed fuel pit (260) cuts the
communication between the float chamber (202) and atmosphere through the drain pipe
(220), so the float chamber (202) remains in communication with the atmosphere
through the air channel (250) only. Therefore, no circulation path is readily formed that
aids in reducing the evaporative emissions from the carburettor (200).
[0039) The fuel vapours formed inside the carburettor (200) during evaporative
emission can escape from the drain pipe (220), but the fuel vapours get condensed inside
the loop(s) (e.g., the curved portion .(221)) of the drain tube (225). As the fuel vapours
are heavier than the atmospheric air, the condensation inside the loop(s) blocks the path
of the air to enter in to the carburettor (200). However, if the amount of vapour becomes
more the vapour starts slowly coming out from the drain pipe (220) of the carburettor
(200).
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[0040] Various embodiments of the present invention provide systems for controlling
the evaporative emissions from the carburettor without installing any additional
component within a vehicle. Various embodiments of the present invention provide
systems for controlling the evaporative emissions that does not require specialized
component to be connected with the drain tube.
[0041] Various embodiments provide systems for controlling the evaporative
emissions from the carburettor wherein the disclosed systems are inexpensive not only in
terms of initial cost but also in terms ·of upkeep since the systems utilize the existing
drain pipe rather than using any additional piping(s). Moreover, the systems for
controlling the evaporative emissions from the carburettor do not require any separate
evaporative emission control valves. In various systems of controlling the evaporative
emissions from the carburettor, the arrangement of controlling the evaporative emission
is easy to mount and service.
[0042] The present invention provides a system of controlling the evaporative
emissions from the carburettor without compromising the aesthetics of the vehicle. The
present invention provides a system for controlling evaporative emissions from a
carburettor without changing existing layout of the vehicle.
[0043] While few embodiments of the present invention have been described above,
it is to be understood that the invention is not limited to the above embodiments and
modifications may be appropriately made thereto within the spirit and scope of the
invention.
[0044] While considerable emphasis has been placed herein on the particular features
of this invention, it will be appreciated that various modifications can be made, and that
many changes can be made in the preferred embodiments without departing from the
principles of the invention. These and other modifications in the nature of the invention
or the preferred embodiments will he apparent to those skilled in the art from the
disclosure. herein, whereby it is to be distinctly understood that the foregoing descriptive
matter is to be interpreted merely as illustrative of the invention and not as a limitation.

CLAIMS
We claim:
1. A carburettor of a vehicle, the carburettor comprising:
·a carburettor body comprising an air intake passage;
a float chamber configured at a bottom portion of the carburettor body;
a drain pipe for discharging excess fuel in the float chamber, the drain p1pe
comp1 ising a first end opening· and a second end opening, the first end opening of the
drain pipe disposed in the float chamber at a position higher than a predefined normal
fuel level in the float chamber and the second end opening of the drain pipe disposed
outside of the float chamber for discharging the excess fuel; and
a drain tube comprising a first end and a second end, the first end of the drain
tube connected to the second end opening of the drain pipe, the drain tube further
comprising at least one condensing provision between the first end and the second end
of the drain tube for facilitating evaporated fuel generated from inside the float chamber
to at least partially condense in the at least one condensing provision.
2. The carburettor as claimed in claim 1 , wherein the at least one condensing
provision comprises one or more curved portions of the drain tube, each curved portion
of the drain tube comprising at least one trough for facilitating condensing of the
evaporated fuel to form a condensed fuel pit, wherein the condensed fuel pit cuts a
communication between the float chamber and atmosphere through the drain pipe.
3. The carburettor as claimed in claim 2, wherein each of the one or more curved
portions of the drain tube is in form of a loop comprising a loop crest and ~ loop
trough, and wherein the loop trough facilitates condensing of the evaporated fuel.
4. The carbtirettor as claimed in claim 3, wherein a vertical level ofthe loop crest is
lower than a vertical level of the fuel in the float chamber.
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5. The carburettor as claimed in claim 2, wherein each of the one or more curved
portions of the drain tube is in form of a sinusoidal configuration.
6. The carburettor as claimed in claim 1, wherein the drain tube is mounted to a
body frame of the vehicle by a mounting means.
7. A carburettor, comprising:
a carburettor body comprising an. air intake passage;
a float chamber configured at a bottom portion of the carburettor body; ;:tnd
a drain pipe for discharging excess fuel in the float chamber,. the drain pipe
comprising a first end opening and a second end opening, the first end opening of the
drain pipe disposed in the float chamber at a position higher than a predefined normal
fuel level in the float chamber and the second end opening of the drain pipe disposed
outside of the float chamber for discharging the excess fuel;
wherein the drain· pipe further comprises at least one condensing provision for
facilitating evaporated fuel generated from inside the float chamber to at least partially
condense in the at least one condensing provisions, the at least one condensing
provision configured between the first end opening and the second end opening within
the float chamber.
8. The carburettor as claimed in claim 7, wherein the at least one condensing
provision comprises one or more curved portions of the drain pipe, each curved portion
of the drain pipe comprising· at least one trough for facilitating condensing of the
evaporated fuel to form a condensed fuel pit, wherein the condensed fuel pit cuts a
communication between the float chamber and atmosphere through the drain pipe.
9. The carburettor as claimed in claim 8, whereiri each of the one or more curved
portions of the drain pipe is in form of a loop comprising a loop crest and a loop.
trough, arid wherein the loop trough facilitates condensing of the evaporated fuel.