FUEL TANK BREATHING SYSTEM
FIELD OF THE INVENTION
The present invention relates to fuel tank and more particularly to fuel tank breathing system.
BACKGROUND
In order to minimize fuel losses to the atmosphere by evaporation from the fuel tank, the
generated gaseous fuel is generally vented . to an evaporated fuel collecting device.
Evaporated fuel collecting device is used to temporarily store the gaseous fuel, generally,
when the engine is not operating and are supplied to the engine when the engine is operating.
The gaseous fuel in the fuel tank is vented out of the fuel tank through breather pipe and
thereafter supplied to the evaporated fuel collecting device through a charge pipe. In order to
prevent entrainment of liquid fuel in the breather pipe and subsequently into charge pipe, for
. example, when the vehicle is driven along a steep incline or as result of splashing when the
vehicle is driven over rough roads or when the vehicle roll over, the breather tube customarily
communicates with the vapour separators which generally mounted in the upper portion of
the fuel tank. Japanese Prior art refer~nce JP05016856 titled "GAS-LIQUID SEPARATOR
OF FUEL TANK" describes a gas-liquid separator installed in a fuel tank for entrainment of
gaseous fuel in a fuel tank.
In order to prevent fuel leakage from the fuel tank in the event of an accidental roll-over of
the vehicle or when the latter is tilted to an extreme angle causes continuous entry of liquid
fuel into evaporated fuel collecting device. Therefore a roll-over valve is connected to the
charge pipe between fuel tank and evaporated fuel collecting device.
Conventional arrangement requires the installation of separator to effectively manage the
evaporated fuel collecting system. However, installation of separator may cause reduction in
the fuel tank capacity. Further, the separator adds to increment in material and cost needed
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for an evaporated fuel collecting system in preventing the entrainment of liquid fuel into
charge pipe.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention itself, together with further features and attended advantages, will become
apparent from consideration of the following detailed 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:
Figure 01 illustrates a side view of fuel tank with a fuel filler structure of a two wheeled
vehicle according to an embodiment of the present invention;
Figure 02 illustrates a rear view of fuel tank with a fuel filler structure of a two wheeled
vehicle according to an embodiment of the present invention;
Figure 03 illustrates a sectional view taken along the line A-A1 in Figure 01 according to an
embodiment of the present invention;
Figure 04 illustrates a view of fuel tank with a fuel filler structure of a two wheeled vehicle
according to an embodiment of the present invention;
· Figure 05A. illustrates an enlarged view of the fuel filler structure with a roll-over valve
according to an embodiment of the present invention;
Figure 05B illustrates a view of the fuel filler structure according to an embodiment of the
present invention.
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
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drawings, if provided along with this description are only meant to make the details of
invention clear and have no effect whatsoever on the scope of the invention.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS AND
PREFERRED EMBODIMENT
While the invention is susceptible to various modifications and alternative forms, an
embodiment thereof has been shown by way of example m the 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 the spirit and the scope of the
invention.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover 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.
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 nun1erals are used to identify the same components .
. . .
m vanous views.
The terms "front I forward", "rear I rearward I backward", "up I upper I top I upward", "down
I downward I lower I lowerward", "left I leftward", "right I rightward" used therein represents
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the directions as seen from a vehicle driver sitting astride and these directions are referred by
arrows Fr, Rr, U, Lr, L, R in the drawing figures.
Figure 01 and Figure 02 illustrate a side view and a rear view of a fuel tank of a two wheeled
vehicle according to an embodiment of the present invention. The fuel tank (100) as per an
embodiment includes a tank body (122) and a bottom member (123) wherein the tank body
(122) and bottom member (123) are fixed to each other, and a sealed closed space (described
later) is formed. The fuel tank (100) has a shape which is elevated at its frontal portion, as
compared with its rear portion so as to maintain the streamlining body structure. Furthelinore,
the lower portion of the fuel tank (1 00) is formed in a bifurcated shape so as to enable the
straddling frame element existing in the centre of vehicle body.
As depicted, the tank body (122) includes a top wall (101), side walls (102A) and (102B)
·extending downwardly from the top wall (101). Bottom member (123) comprises of bottom
walls (103A) and (103B) and a tunnel wall (104). Bottom walls (103A) and (103B) extending
toward each other from the side walls (102A) and (102B), and a tunnel wall (104) extending
between the bottom walls (103A) and (103B) and defining an inverse U-shaped cavity (105)
(Visible in Figure 02 and Figure 03) of the fuel tank (100). The inverse U-shaped cavity
(105) is formed along the longitudinal direction of the fuel tank (100). In the illustrated
construction, the top wall (101) and side walls (102A) & (102B) form aesthetic shape of a
fuel tank (100) and are contoured accordingly. It should be appreciated that fuel tank shapes
vary and such shapes are often selected to achieve desirable aesthetic appearances.
The fuel tank (100) has an enlarged forward end (107) and a tapered rearward end (108)
(distinctly visible in Figure 04). The top wall (101), side walls (102A) and (102B), bottom
walls (103A) and (103B) and tunnel wall (104) are joined to define a sealed closed space to
be used as fuel chamber (111). The fuel chamber (111) has its first side (112) and second side
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(113) (visible in figure 03). The inverse U-shaped cavity (105) extends between the first and
second· side (112) and (113) of fuel tank (100). The inverse U-shaped cavity (105) forms a
part of fuel tank ( 1 00) that straddles along the main frame of a two wheeled vehicle.
The tank body (122) on its top wall (101) is crowned to form a fuel cap opening portion
(124). The fuel cap opening portion (124) is equipped with fuel filler structure (118), the fuel
filler structure (118) is provided with an opening in its central region. In an embodiment, the
fuel filler structure (118) is welded to the fuel cap opening portion (124) of fuel tank (100).
With reference to Figure 04, the fuel filler structure (118) has an opening portion (129)
penetrating the top wall (101) of fuel tank (100) and can be covered by a removable tank cap
(not shown). By the removable tank cap (not shown) being removed, the fuel filler structure
( 118) communicates the inside and outside of the fuel tank ( 100), whereby fuel filling to the
fuel tank (1 00) is made possible.
Figure 05A illustrates the enlarged view of the fuel filler structure of a fuel tank. The fuel
filler structure (118) includes a fuel filler guide tube (130) extending from opening portion
(129) to the inside of fuel tank (1 00) into which the fuel dispenser is inserted. The fuel filler
guide tube (130) includes a tube main body (131) of cylindrical shape and a mounting portion
(132). A tray (133) is disposed around the fuel filler structure (118) for receiving fuel
overflown to the outside from the fuel filler structure (118) upon fuelling. The tray (133) has
a protruding outlining wall (140) for securing the boundary of fuel tray (133).The fuel tray
(133) has a drain hole (134) for discharging the fuel flowing into the fuel tray (133) through a
drain pipe (121). The drain pipe (121) is a metallic tube arranged to extend inside the fuel
tank body (122) towards the bottom plate and protrudes out of the fuel tank (100). The
outlining wall (140) has a hole (141) provided in proximity of drain hole (134).
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The fuel filler structure (118) is adapted to be fitted and locked with a removable tank cap
wherein the locking of fuel filler structure (118) with removable tank cap (120) is facilitated
by key cylinder (Not visible in drawings).
A breather pipe (119) is disposed adjacent fuel filler guide tube (130) of fuel filler structure
(118). As illustrated in Figure 05B, the breather pipe (119) has its first end (135) opening .to
the inside of the fuel tank (100) and above the highest level of fuel in the fuel tank. The
second end (136) of breather pipe ·(119) is connected to the evaporated fuel collecting device
(Not shown in drawings). The first end (135) of breather pipe (119) penetrates the outlining
wall (140) of fuel tray (133) through the hole (141) and the hole (141) provides a firm
arrangement for first end (135) of breather pipe (119). The hole (141) is then sealed to avoid
any leakage.
Figure 05A illustrates an enlarged view of fuel filler structure and Figure 04 illustrates a top
view of the fuel tank (100) according to an embodiment of the present invention. The
breather pipe (119) and drain pipe (121) are so arranged that the drain pipe (121) envelopes
the breather pipe (119) such that enveloped arrangement of breather pipe (119) with drain
pipe (121) is a pipe within a pipe arrangement. The outer diameter of breather pipe (119) is
lesser than the inner diameter of the drain tube ( 121 ). In a preferred embodiment, the outer
diameter of breather pipe (119) is approximately 50% of the inner diameter of the drain tube
(121 ). The disposition of breather pipe ( 119) within the drain pipe (121) is such that it does
not cause any restraint for the flow of overflowing or spilled fuel, extra contaminants from
the drain pipe (121). In an embodiment as illustrated in Figure 05A, the first end of breather
pipe (119) is provided connected to a roll-over valve (126) inside the fuel tank (100). The
roll-over valve (126) is a conventional valve mounted inside the fuel tank (100). In an
embodiment, the roll-over valve (126) is mounted to the fuel filler structure (118) through a
collar spot welded to the fuel filler structure (118). In an embodiment, the roll-over valve
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(126) can be mounted outside of the fuel tank (100) and the second end (136) of breather pipe
(119) is connected to the roll-over valve (126). It should be noted that breather pipe (119) is
made up of such material that the exposure of breather pipe (119) to the fuel does not cause
any adverse effect to the breather pipe (119).
When the breather pipe (119) is provided within the drain tube (121) manufacturer gets the
option to select the material of breather pipe (119) which is essentially of metal in
conventional designs. Thus, cost effective.
The present invention provides a fuel tank breathing system designed to offer flexibility in
terms of material constituting the breather pipe.
The present invention provides a fuel tank breathing system which is cost effective in nature.
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.
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 be 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 fuel tank breathing system, comprising:
a breather pipe for breathing evaporated fuel generated in a fuel tank, the breather
pipe having·a first end and a second end, the first end positioned above the highest level
of fuel in the fuel tank and the second end connected to an evaporated fuel collecting
device outside of the fuel tank,
wherein a portion of the breather pipe in the fuel tank is enveloped by a drain
pipe connecting a drain hole configured in a fuel tray to outside ofthe fuel tank.
2. The fuel tank breathing system as claimed in claim 1, wherein the fuel tray
comprises a protruding outlining wall for securing a boundary of the fuel tray, and the
first end of the breather pipe penetrates the protruding outlining wall of the fuel tray
through a hole configured in the protruding outlining wall such that an opening of the
first end is positioned in the fuel tank for breathing of the evaporated fuel.
3. The fuel tank breathing system as claimed in claim 1, further comprising a rollover
valve connected to the first end of the breather pipe.
4. The fuel tank ~reathing system as claimed in claim 3, wherein the roll-over valve
is mounted to a fuel filler structure inside the fuel tank.
5. The fuel tank breathing system as claimed in claim 1, further comprising a rollover
valve coupled to the second end of the breather pipe.
6. The fuel tank breathing system as claimed in any of the claims 1 to 5, wherein the
breather pipe is a non-metallic pipe.
7. The fuel tank breathing system as claimed in any of the claims 1 to 5, wherein the
drain pipe is a metallic pipe.
8. , A fuel tank, comprising:
a tank body;
a fuel filler structure comprising a fuel filler guide tube for enabling a fuel
dispel)ser for fuelling a fuel chamber configured by the tank body through an opening in
a top wall of the tank body;
a fuel tray disposed around the fuel filler structure for receiving fuel overflown
from the fuel filler structure, the fuel tray comprising a protruding outlining wall for
securing the boundary of the fuel tray;
a drain pipe connecting a drain hole configured in the fuel tray to outside of the
fuel cham bet to discharge fuel overflown to outside from· the fuel filler structure·; and
a breather ·pipe for breathing evaporated fuel generated in the fuel chamber, the
breather pipe having a first end and a second end, the first end positioned above the
highest level of fuel in the fuel chamber and the second end connected to an evaporated
fuel collecting device, wherein a portion of the breather pipe in the fuel chamber is
enveloped by the drain pipe.
9. The fuel tank as claimed m claim 8, further comprising a roll-over valve
connected to the first end of the breather pipe.
10. The fuel tank as claimed in claim 9, wherein the roll-over valve is mounted to the
fuel filler structure inside the fuel chamber.
11. The fuel tank as claimed in claim 8, further comprising a roll-over valve coupled
to the second end of the breather pipe.
12. The fuel tank as claimed in any ofthe claims 8 to 11, wherein the breather pipe is
a non-metallic pipe.
13. The fuel tank as claimed in any of the claims 8 to 11, wherein the drain pipe is a
metallic pipe.