Air breather device for a tank

An air breather device for a tank includes a fuel tank for a road vehicle disposed in the frame of the vehicle and an air breather pipe disposed along the lateral side of the fuel tank perpendicular to the fore and aft direction of the frame. A first opening at one extremity of the air breather is disposed in an air space in the fuel tank while a second opening at the other extremity of the air breather is opened to the atmosphere. The air breather passes through the wall of the fuel tank and the first opening is situated in the neighborhood of the inner wall of the fuel tank opposite from the second opening. In this way even if the vehicle turns over on its right or left side, part of the air breathing pipe will remain disposed above the fuel or oil level such that the fuel or oil will be prevented from leaking from the tank.

BACKGROUND OF THE INVENTION 
This invention relates to fuel tanks and oil tanks on industrial vehicles 
such as forklift trucks. More particularly, it relates to an air breather 
provided for fuel tanks and oil tanks. 
In general, fuel and oil tanks are provided with air breathers in order 
that the fuel or oil to be stored in the tanks can be smoothly introduced 
into and discharged out of the tanks. Heretofore, as the construction for 
such an air breather, an air-breathing through-hole was formed in an oil 
filler cap applied to an oil filler opening. As far as the Applicant is 
aware, there is no literature or publication disclosing the aforementioned 
construction of an air breather device for tanks, but a construction for 
air breather devices used in industrial vehicles so far produced by the 
Applicant for company use is shown in FIG. 1. 
This figure is a sectional view showing a prior-art example wherein a 
retainer 9 is projectedly mounted to the top of a main body 8 of the tank 
and a cap 9a is removably mounted to the foremost opening portion of the 
retainer. A rubber seal 9c is fitted to the inside of the cap 9a. The 
rubber seal 9c and the cap 9a are respectively provided with air breather 
through-holes 9d and 9b in communication with each other. 
In the case of the air-breather device in which the air-breather 
through-holes are formed in the oil filler cap as described hereinabove, 
the fuel or oil in the tank 8 can leak into the engine compartment by way 
of the air-breather through-hole 9d if the vehicle should turn over. In 
particular, the lift truck may catch on fire should the fuel leak into the 
engine compartment which is an especially dangerous possibility. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a highly effective 
means for obviating the above described disadvantages. For achieving the 
object, the present invention provides an air breather system for a tank 
comprising a fuel tank disposed in a frame, an air breather pipe disposed 
along the lateral side of the fuel tank perpendicular to the fore and aft 
direction of the chassis, a first opening at one extremity of said air 
breather, said first opening being disposed in an air space in said fuel 
tank, and a second opening at the other extremity of said air breather 
pipe, said second opening being open to the atmosphere, said air breather 
pipe passing through the wall of said fuel tank and said first opening 
being situated in the neighborhood of the opposite inner wall of the fuel 
tank from said second opening.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Reference is now made to the accompanying drawings showing certain 
preferred embodiments of the present invention. 
Referring first to FIGS. 2 through 5, A designates the main body of a truck 
and B is a lift unit mounted to the foremost part of the main body A. In 
the main body A, numeral 1 designates front wheels, 2 designates rear 
wheels, 3 is a chassis supported on the wheels 1 and 2, numeral 4 is a 
front protector, numeral 5 is an engine hood, numeral 6 is a driver's seat 
and 7 is a head guard. Within the frame 3 and in a space surrounded by 
left and right side frames 3a, 3a and the engine hood 5, there is provided 
an engine room, not shown. Within the engine room, besides an engine, a 
transmission casing and a crank case, there is also provided a fuel tank 8 
which is offset towards one of the side frames 3a. An oil tank, also 
termed a fuel tank 8 in the present invention, is provided towards the 
other side frame 3a. In the present embodiment, the fuel tank is provided 
towards the left side of the vehicle chassis. On the top of the fuel tank 
8 is provided an oil filler tube 9 to project out of the fuel tank 8 at an 
inclination towards one lateral side, in the present embodiment, towards 
the left hand side in the forward direction, of the vehicle. At 
approximately the center of the top of the fuel tank 8, a vertically 
extending boss 10 is provided vertically. The boss 10 is in the form of a 
hollow cylinder with its one end communicating with the interior of the 
fuel tank 8. On the surface of the hollow interior of the boss 10 is 
formed a female threaded portion 10a. To a lower opening 10b of the boss 
10, there is connected a union eye 12 having its union bolt 11 threadably 
connected to the female threaded portion 10a formed in the opening 10b. 
Similarly, to an upper opening 10c, there is connected another union eye 
14 having its union bolt 13 threadably connected to the female threaded 
portion 10a formed in the opening 10c. The union bolts 11, 13 are 
respectively provided with through-holes 11a, 13a, through which the union 
eyes 12, 14 are in communication with each other. To the union eye 12 is 
connected a first pipe 15 having a first opening 15a. The pipe 15 extends 
horizontally into an air space 8a in the upper part of the fuel tank 8 and 
towards one lateral side of the base block 3, in the present embodiment, 
towards the left side in the forward direction or towards the side 
opposite from a hose 17 to be described later. Similarly, to the union eye 
14, there is connected a second pipe 16 having a second opening 16a and 
horizontally extending towards the other side of the base block, in the 
present embodiment, towards the right in the forward direction. Stated 
differently, the pipes 15 and 16 are provided to extend horizontally 
towards both sides of the frame with a 180.degree. angle of offset from 
each other and at right angles with the fore and aft direction of the 
frame 3. To a second opening 16a which is at the distal end of the second 
pipe 16 the hose 17 of a suitable length is connected, with the free end 
of the hose 17 being situated outside of the engine room within the frame 
3. In this manner, an air breather pipe 18 is constituted by the 
aforementioned first and second pipes 15 and 16. 
The numeral 9a designates a cap applied to the fuel supply tube 9. No air 
breather holes are formed in the cap 9a so that the tank is hermetically 
sealed when the cap is screwed onto the tube. 
The device so far shown and described operates as follows. 
(i) During normal operation 
During normal operation of the forklift truck, the air space 8a formed in 
the upper end of the fuel tank 8 is communicated with air outside the 
engine room by way of the air breather pipe 18. 
(ii) When turned over 
If the forklift truck turns over on its left side with respect to the 
forward direction, the first pipe 15 becomes immersed in the fuel, as 
indicated in FIG. 4. However, since the pipe 16 projects above the fuel 
level F, fuel is prevented from leaking from the air breather 18. If the 
forklift truck turns on its right side with respect to the forward 
direction, the first pipe 15 projects above the fuel level F as indicated 
in FIG. 5, so that fuel leakage from the air breather pipe 18. is also 
prevented. However, not only when the first pipe 15 is immersed in the 
fuel as shown in FIG. 4, but also when the first pipe 15 projects above 
the fuel level F, as shown in FIG. 5, a certain amount of the fuel finds 
its way into the air breather pipe 18 because of the shock of turning 
over. However, the fuel thus introduced into the air breather pipe 18 will 
be discharged out of the engine room by way of the hose 17 without leaking 
into the engine room. 
In the above embodiment, the second pipe 16 on one side of the boss 10 is 
mounted outside the fuel tank 8 while the first pipe 15 on the other side 
of the boss 10 is mounted within the fuel tank 8. However, the piping 
structure of the air breather pipe is not limited to that shown and 
described in the above embodiment. For example, as shown in FIG. 6, the 
air breather pipe may be disposed outside the fuel tank 8 or on the 
opposite side of the fuel tank from the air breather pipe mounted along 
the tank such that only the open end of the air breather pipe will be 
facing the peripheral edge of the air space 8a. Alternatively, as shown 
the air in FIG. 7, the air breather pipe may be drawn from the side wall 
of the fuel tank 8 into the air space such that the open end of the air 
breather pipe will be facing the peripheral edge of the air space 8a. 
Namely, (a) the piping structure in which the air breathing piping 18 is 
extended towards the upper edge of the tank 8 along the left and right 
sides of the frame; (b) the piping structure in which the first opening 
15a of the air breather pip 18 is positioned facing the peripheral edge of 
the inner wall of the air space 8a; or (c) the piping structure in which 
the other or second opening 16a of the air breather pipe 18 is disposed 
outside the engine room 8a, are all included within the scope of the 
present invention. 
In the above described construction of the present invention, when the air 
breather pipe extends along the upper surface of the tank, it is set so as 
to extend vertically along the lateral sides of the tank parallel to the 
fore and aft direction of the main body of the vehicle with one extremity 
thereof opening into the atmosphere and the other extremity thereof 
opening into the air space in the upper end of the tank, said other 
extremity being disposed at the side opposite from the vertically 
extending portion of the air breather pipe in such a fashion that, no 
matter whether the vehicle turns over on its right or left side, the air 
breather pipe still partially projects above the fuel or oil levels, 
thereby effectively preventing the fuel or oil from leaking. 
When the other opening or extremity of the air breather pipe is disposed 
outside the engine room as described above, that portion of the fuel or 
oil running into the air breather pipe can be discharged outside the 
engine room, thereby preventing an engine fire if the forklift turns over 
further improving operating safety of the lift truck.