Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Reexamination Certificate
1999-07-20
2002-05-07
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
C123S518000, C220S004140
Reexamination Certificate
active
06382172
ABSTRACT:
TECHNICAL FIELD
This invention concerns a fuel tank and the general purpose engine equipped with the same.
BACKGROUND
Fuel tanks for automobile engines or the sort of general purpose engines used in farm equipment are produced by pressing an upper portion and a lower portion out of sheet metal and joining the two with a flange.
Fuel tanks for automobiles are generally installed under the floor panel in the rear part of the body. On the upper surface of the fuel tank are several grooves running from front to rear to accommodate the drive shafts and the live axle which transmits the steering force. Water tends to accumulate in these grooves, causing the tank to rust.
The fuel tank shown in
FIGS. 5 and 6
is designed to prevent this problem from occurring. The design of this automobile fuel tank is disclosed in the publication (Kokai) of Japanese Utility Model 63-159324.
FIG. 5
is a plan view and
FIG. 6
is a cross section taken along line C—C in FIG.
5
.
In
FIGS. 5 and 6
,
1
is the fuel tank;
11
is the gearbox to operate the rear wheels which is installed behind fuel tank
1
;
12
and
13
are the pinion shaft and the rack shaft;
14
is the universal joint; and
15
is the shaft to transmit the steering force.
On the upper surface of the fuel tank
1
there is a groove
5
which traverses the tank from front to rear. This groove
5
accommodates the shaft
15
, universal joint
14
and pinion shaft
12
. The upper surface
2
of the tank is divided in two by the groove
5
. On the rear portion of this surface, on either side of groove
5
, are expanded portions
3
, which help provide the necessary volume by protruding above the rest of the tank. The surface of the fuel tank
1
is coated with a rust-proofing substance. In the drawing,
4
is the fuel inlet;
31
is the surface where the fuel pump is mounted;
32
is the surface where the gauge unit is mounted; and
41
is the vent pipe.
The bottom of the groove
5
, as can be seen in the lateral view in
FIG. 6
, comprises a long inclined surface
6
which slants down toward the front of the tank and a short inclined surface
7
which slants down toward the rear of the tank. Together, the two inclined surfaces give the groove a convex bottom. A resin coating is applied to the surface of the groove. Its apex
8
is located between the two expanded portions
3
at the rear of the tank. If any water should get into the groove
5
, it will discharge along forward-sloping surface
6
and rearward-sloping surface
7
until it is discharged onto the ground at the edges of the tank.
Leaving automobile fuel tanks for a moment, let us turn our attention to the fuel tanks used in small general purpose engines. In these engines, the fuel inlet is generally on the top of the tank. When this type of fuel tank is filled, some of the fuel is liable to overflow from the fuel inlet or drip from the filling nozzle and spread over the surface of the tank. If it touches the cylinder, which is extremely hot, it may start on fire; if it comes in contact with an electrical component, it may lead to malfunctioning.
To prevent such problems, a design for the fuel tank of a small general purpose engine has been proposed such that there is a groove near the fuel inlet to carry off any spilled fuel. The groove is slanted like that shown in
FIGS. 5 and 6
so that it can discharge the fuel in a given direction onto the ground.
We shall discuss such a fuel tank belonging to the prior art with reference to
FIGS. 7 and 8
.
FIG. 7
is a front view of a general purpose engine with the fuel tank described above;
FIG. 8
is a plan view of the same engine. In
FIGS. 7 and 8
,
50
is the engine;
51
is the engine body;
52
(see
FIG. 8
) is the output shaft;
53
is the muffler;
54
is the air cleaner;
55
is the carburetor;
56
and
57
are the throttle and choke levers;
58
is the recoil starter; and
59
is the grip of the recoil starter
58
.
61
is the fuel tank;
60
is the fuel cock which is connected to the fuel tank
61
;
62
is the gauge unit;
63
is the label; and
64
is the cap for the fuel inlet. The cylinder shaft (not pictured) of engine body
51
is canted from below muffler
53
toward output shaft
52
.
Fuel tank
61
comprises two pan-shaped portions which are pressed from thin copper sheeting. These portions are seam-welded along flange
61
a
, which runs along the periphery of the tank. The upper surface of the tank is level in the center and inclines slightly toward the edges. The area around fuel inlet
61
b
(see
FIG. 7
) in the center of the tank forms a depression bounded by conical surface
61
c
. The bottom of the depression extends toward recoil starter
58
and is inclined downward by a suitable amount toward the outer edge of the tank. Its cross section is a trapezoid with downward-sloping sides, which we shall call depression
61
d
. The end of this depression opens onto recoil starter
58
. Any fuel spilled at the fuel inlet is thus conducted toward recoil starter
58
and sluiced off the top of the tank.
In the device pictured in
FIGS. 7 and 8
, the hot cylinder and the electrical components are concentrated on the left side of fuel tank
61
. It is crucial, then, to prevent any spilled fuel from entering this region.
A fuel tank
61
for a general purpose engine like that shown in
FIGS. 7 and 8
has a depression
61
d
around the fuel inlet on the top of the tank, and the bottom of the depression is angled toward recoil starter
58
. If fuel overflows during fueling or drips from the nozzle onto the tank, it will flow in a sideways direction, either to the left or right of the tank, and be discharged out of depression
61
d.
Similarly, with the fuel tank
1
for an automobile engine which is pictured in
FIGS. 5 and 6
, the spilled fuel which discharges into depression
5
goes down to the edge of the tank and is routed horizontally along the flange.
If this horizontally-discharging spilled fuel should come in contact with the hot cylinder, it may combust; if it should come in contact with electrical components, their function may be impaired or they may fail. And because both the tanks
61
and
1
consist of two halves made of thin copper sheeting, they tend to experience vibration and noise due to sympathetic vibration with the engine.
DESCRIPTION OF THE INVENTION
In view of the above-described problems inherent in the prior art, the first object in designing this invention is to improve the safety of the engine by preventing fuel which overflows the inlet or splashes onto the top of the tank during fueling from dripping down onto the hot cylinder or coming in contact with any electrical component.
The second object is to provide an engine whose fuel tank will not be subject to vibration or its resultant noise.
The invention which solves these problems is a fuel tank comprising an upper and lower half which are joined with a flange, with the fuel inlet on the top of the tank.
This fuel tank is distinguished by the fact that the upper portion of the tank has a depression on its upper surface which contains the fuel inlet and which angles downward toward one side of the tank. A gutter is provided on along the outer edge of the flange to collect the spilled fuel, and this gutter has a number of openings to conduct the fuel from the gutter to the exterior.
Preferably, in addition to the depression, a number of semicircular grooves which open in one direction should be provided on both sides of the depression in order to collect the spilled fuel.
It is also desirable that the gutter on one side of the tank down which the spilled fuel discharges should be segmented by ribs and one of the openings described above should be provided for each segment between the ribs.
The aforesaid fuel tank would be ideally suited for use with a general purpose engine.
In other words, this sort of engine has a fuel tank on top of the engine comprising an upper portion with a fuel inlet on its top and a lower portion which is mounted to the engine body. A recoil starter is placed on the end of the crankshaft. This engine is
Kobayashi Kazuyuki
Kouchi Hiroyoshi
Mizukami Shin
Nakamura Shogo
Crowell & Moring LLP
Yuen Henry C.
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