BACKGROUND OF THE INVENTION
[Field of the Invention]
[0001] This invention relates to a fuel feed apparatus and, more particularly, it relates
to a technology that can be effectively applied to an in-tank type fuel feed apparatus
having a fuel pump arranged inside a fuel tank.
[Related Art Statement]
[0002] Conventionally, so-called in-tank type fuel feed apparatus having a fuel pump and
a strainer arranged inside a fuel tank are popularly used for motor bicycles and motor
cars.
[0003] Many fuel feed apparatus of the so-called in-tank type of motor bicycles and motor
cars comprise a sub-tank arranged within the fuel tank that operates to prevent any
possible interruption of fuel supply that can arise when the bicycle or the car drives
up a slope of is subjected to vibrations. In such apparatus, normally a box-like or
sleeve-like reservoir is arranged as sub-tank in the fuel tank and the fuel pump is
adapted to suck fuel from the sub-tank so that the fuel suction port may not emerge
from the fuel in the tank and exposed to air if the motor bicycle or the motor car
is inclined while in motion. With this arrangement, fuel may be supplied on a stable
basis even when the motor bicycle or the motor car is shaken.
[0004] However, motor bicycles and motor cars provided with such a fuel feed apparatus can
be tilted for a prolonged period of time, during which fuel is fed to the engine.
Particularly, motor bicycles can often be forced to prance on the rear wheel or rest
on a side prop stand in an inclined state, while fuel has to be fed to the engine
continuously. In such a case, the fuel in-take port can be found very low and fuel
can flow out therethrough, although the sub-tank is provided, to make it no longer
possible to supply fuel to the engine for a prolonged period of time on a stable basis.
[0005] Meanwhile, in in-tank type apparatus, one or more than one filter members such as
paper filters and/or synthetic resin filters are contained in the strainer in order
to filter the fuel discharged from the fuel pump. However, the fuel passing through
the filter can easily generate static electricity due to its friction with the filter
materials. Additionally, the fuel can give rise to turbulence before and after passing
through the filter to cause friction between the synthetic resin case and fuel, which
also consequently generates static electricity.
[0006] Japanese Patent Application Laid-Open No. 8-232792 proposes an in-tank type fuel
pump apparatus wherein grounding lead wires are connected to the fuel filter to allow
the generated static electricity to flow to the ground. A lead wire is connected to
each of the components housed in the tank. Then, the lead wires are electrically connected
with the vehicle wire harness so that the components are grounded and prevented from
becoming electrically charged.
[0007] Japanese Patent Application Laid-Open No. 10-220315 proposes the use of a filter
case made of an electrically conductive material so that the generated static electricity
may be discharged into the fuel in it from the outer peripheral surface thereof. The
above identified patent document also discloses a technique of connecting lead wires
to the electrically conductive filter case at an end and to a grounding electrode
outside of the fuel tank at the other end in order to allow the static electricity
generated in the filter case to flow to the ground. If the fuel tank is made of metal,
the lead wires are also connected to it so that the static electricity generated there
may directly flow to the ground.
[0008] Meanwhile, fuel tanks are generally provided with a warning sensor comprising a thermistor
for notifying the driver with the volume of fuel left in the fuel tank when the fuel
in the tank falls below a certain threshold level. Generally, electricity flows through
such a thermistor at a very low rate and hence the thermistor generates heat to a
small extent. When the fuel tank is full of fuel and the thermistor is dipping in
the fuel, the fuel cools the thermistor and hence its temperature would not rise.
If, on the other hand, the fuel level falls to make the thermistor emerge from the
fuel, the fuel no longer cools it and its temperature rises.
[0009] The electric resistance of a thermistor changes as its temperature. Therefore, the
volume of fuel left in the tank can be detected by detecting the change in the electric
resistance of the thermistor. Thus, thermistors are popularly used as the above described
sensors. Then, lead wires connected to the thermistor are also arranged in the fuel
tank so that the signal from the thermistor is received by way of the lead wires to
detect the volume of fuel left in the tank.
[0010] However, many other wires are already found in the fuel pump including those for
preventing the strainer from being electrically charged and those for feeding the
motor with electricity. Therefore, as wires are laid for the thermistor, the number
of wires in the fuel tank will be enormous if the wires on the negative side are put
together. This means that the provision of a thermistor entails an increase in the
workload of wiring operations, in the number of parts and in the manufacturing cost.
SUMMARY OF THE INVENTION
[0011] Therefore, it is an object of the present invention to provide a fuel feed apparatus
that can stably supply fuel for a long time if the body of a motor bicycle or a motor
car is inclined.
[0012] Another object of the present invention is to provide a fuel feed apparatus having
a simple configuration with a reduced number of components that requires only a simplified
wiring operation.
[0013] According to the invention, the above objects are achieved by providing a fuel feed
apparatus to be used for a motor bicycle or a motor car, said apparatus comprising
a reservoir containing a fuel pump therein and adapted to store fuel to be sucked
by said fuel pump, said reservoir having a fuel in-take port for introducing fuel
into the inside thereof, said fuel in-take port being arranged at a position where
it is made to face upward when the body of the motor bicycle or the motor car is inclined.
[0014] With the above arrangement, fuel would not flow out of the sub-tank through the fuel
in-take port if the body is inclined. Thus, fuel can be supplied to the engine on
a stable basis for a long period of time without making the sub-tank useless if the
body is inclined.
[0015] In the case of a motor bicycle provided with a side prop stand, said fuel in-take
port may be so arranged as to face upward when the motor bicycle is made to rest on
the side prop stand. Alternatively, said fuel in-take port may be so arranged as to
face upward when the motor bicycle is made to prance. In either case, the motor bicycle
can feed the engine with fuel stably for a long period of time.
[0016] Additionally, the inside of the fuel in-take port may have a labyrinth structure.
Then, fuel will be further prevented from flowing out through the fuel in-take port.
[0017] Still additionally, there is also provided a strainer for filtering the fuel discharged
from said fuel pump, a sensor for detecting the amount of the residual fuel in the
fuel tank and a sensor holder made of an electrically conductive material and arranged
in said fuel tank to hold said sensor, said sensor holder having a strainer-connecting
section connected to said strainer and an earth-connecting section electrically connected
to the grounding terminal of said sensor.
[0018] With a fuel feed apparatus according to the invention and having a configuration
as described above, the sensor holder can be commonly used as the grounding terminal
of the strainer and also as that of the sensor to eliminate not only the grounding
wire of the strainer but also the step of arranging the grounding wire of either the
strainer or the sensor. Thus, both the number of parts and that of processing steps
can be reduced in the process of building the apparatus.
[0019] A thermistor may be used for said sensor, additionally, said sensor holder may be
formed by using a metal wire having said strainer-connecting section formed at an
end thereof and said earth-connecting section formed at the opposite end thereof.
[0020] The above-described and other objects and novel feature of the present invention
will become apparent more fully from the description of the following specification
in conjunction with the accompanying drawings.
BRIEF DESCRIPTIO N OF THE DRAWINGS
[0021]
FIG. 1 is a schematic lateral view of an embodiment of fuel feed apparatus according
to the invention and arranged in position.
FIG. 2 is a partially exploded schematic perspective view of the embodiment of fuel
feed apparatus according to the invention.
FIG. 3 is a schematic lateral view of the embodiment of fuel feed apparatus according
to the invention, illustrated partly in cross section.
FIG. 4 is a schematic plan view of the embodiment of fuel feed apparatus according
to the invention.
FIG. 5 is a schematic cross sectional partial view of the embodiment of fuel feed
apparatus according to the invention taken along line A-A in FIG. 4.
FIG. 6 is a schematic cross sectional partial view of the embodiment of fuel feed
apparatus according to the invention taken along line B-B in FIG. 4 to illustrate
the configuration of the pressure regulator fitting section.
FIG. 7 is a schematic lateral view of the embodiment of fuel feed apparatus according
to the invention.
FIG. 8 is a schematic plan view of the embodiment of fuel feed apparatus according
to the invention, where the holder and the coupling cover are removed.
FIG. 9 is a schematic lateral view of the embodiment of fuel feed apparatus according
to the invention, illustrating how the thermistor is fitted and wired.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Now, the present invention will be described by referring to the accompanying drawings
that illustrate a preferred embodiment of the invention. FIG. 1 is a schematic lateral
view of an embodiment of fuel feed apparatus according to the invention and arranged
in position. FIG. 2 is a partially exploded schematic perspective view of the embodiment
of fuel feed apparatus according to the invention. FIG. 3 is a schematic lateral view
of the embodiment of fuel feed apparatus according to the invention, illustrated partly
in cross section. FIG. 4 is a schematic plan view of the embodiment of fuel feed apparatus
according to the invention.
[0023] The fuel feed apparatus 1 of this embodiment (hereinafter referred to simply as "apparatus")
is adapted to operate as in-tank type gasoline feed apparatus to be used with a motor
bicycle. As shown in FIG. 1, the apparatus 1 is fitted to an opening 3 formed through
the bottom 2a of a fuel tank 2 from below. As shown in FIGS. 2 and 3, it comprises
a cup-shaped unit base 4 containing a fuel pump 5, a strainer 6 and a pressure regulator
7 along with other components to realize in the form of a module. The apparatus 1
purifies fuel 42, sucked up by the pump 5, by means of the strainer 6 and regulate
the pressure of the fuel to a predetermined level by means of the pressure regulator
7 before feeding it to the engine by way of a fuel feed pipe 43.
[0024] A flange 4a is formed as bottom plate at the bottom of unit base 4. The flange 4a
is formed integrally with reservoir 4b operating as lateral wall from synthetic resin
by molding. The apparatus 1 is oil-tightly secured to the tank 2 as it is fitted to
the opening 3 by way of a packing 8. Thus, the fuel feed apparatus 1 according to
the invention is a module that can be installed by simply fitting it to the tank 2
and hence can remarkably improve the efficiency of mounting operation.
[0025] The inside of the unit base 4 of the apparatus 1 is empty and adapted to contain
the pump 5 and other components and operate, at the same time, as a sub-tank 16. In
other words, the unit base 4 functions as reservoir so that the fuel 42 sucked up
by the pump 5 is temporarily stored in the unit base 4 in order to avoid any improper
supply of fuel that can arise when the motor vehicle drives up a slope or is fiercely
shaken. While conventional sub-tanks comprise a plurality of components typically
as shown in FIG. 10, that of apparatus 1 of the present invention comprises only a
unit base 4. Thus, the apparatus 1 has a reduced number of components to consequently
reduce the manufacturing cost thereof.
[0026] As seen from FIGS. 2 and 3, a holder 9 is fitted to an upper portion of the reservoir
4b and operates as closure for sub-tank 16. The pump 5 and strainer 6 are held by
the holder 9 and housed in the unit base 4. Meanwhile, a fuel suction port 10 is arranged
under the pump 5 to draw fuel 42 from the bottom of the sub-tank 16. The port 10 is
provided with a filter 13 to make fuel 42 get rid of coarse pieces of dirt.
[0027] The pump 5 and the strainer 6 are linked by a coupling cover (coupling member) 11
that contains a check valve 20 therein. FIG. 5 shows the configuration of the cover
11 and it is taken along line A-A in FIG. 4. As seen from FIG. 5, the valve 20 contained
in the cover 11 is mounted in a fuel flow path 21 and operates to prevent fuel from
flowing reversely from the strainer 6 to the pump 5. The valve body 20a of the valve
20 is urged toward small diameter portion 21a of the path 20 by spring 20b. Thus,
fuel is allowed to flow from the pump as the spring 20b is compressed under the fuel
discharging effect of the fuel pump 5, whereas fuel is prevented from flowing from
the strainer 6 by the valve body 20a.
[0028] The pump 5 and the strainer 6 are held in position by the holder 9 and linked together
by the cover 11 at an upper portion thereof. Thus, the pump 5 and the strainer 6 are
linked together simply by arranging the cover 11 at an upper portion thereof in the
apparatus 1. The cover 11 can be used to streamline the profile of the apparatus 1
in order to reduce both the size and the weight of the apparatus 1 particularly at
the opposite lateral sides thereof. Thus, the cover 11 provides free space along its
opposite lateral sides if compared with an apparatus of the same type that is covered
by a cup-shaped cover.
[0029] It will be appreciated that the cover 11 provides a space for installing the check
valve 20 while it is operating as a coupling member. Therefore, the cover 11 not only
cuts unnecessary space to reduce both the size and the weight of the apparatus 1 but
also eliminates the space that may otherwise be required for the check valve to reduce
the height of the apparatus.
[0030] Additionally, the connecting section for connecting the pump 5 and the cover 11 of
the apparatus is designed to be space saving. More specifically, the pump 5 is provided
at an upper portion thereof with a recess 22 for connecting itself to the cover 11.
On the other hand, the connecting section of the cover 11 for connecting itself to
the pump 5 is provided with a projection (engaging section) 23 to be engaged with
the recess 22. Thus, the pump 5 and the cover 11 are linked together as the recess
22 and the projection 23 are held in mesh with each other. With this arrangement,
the connecting section for connecting the pump 5 and the cover 11 is highly space
saving to consequently reduce the height of the apparatus. It may be appreciated that
alternatively the pump 5 may be provided with a projection while the cover 11 may
be provided with a recess for connecting them.
[0031] Meanwhile, the strainer 6 is provided at a lower portion thereof with a joint 12,
which joint 12 is connected to a pressure regulator 7. FIG. 6 is a schematic cross
sectional partial view of the configuration of the pressure regulator fitting section.
As shown in FIG. 6, the joint 12 is arranged between a lower portion of the strainer
6 and discharge port 14 projecting from the bottom of the unit base 4. The pressure
regulator 7 is connected to a central portion of the joint 12. Thus, the fuel fed
from the pump 5 is regulated for pressure by the pressure regulator 7 and then forwarded
to the engine so that any excessive fuel is returned to the fuel tank 2 by the pressure
regulator 7.
[0032] On the other hand, the apparatus 1 is used in a fuel feed system that may be a so-called
return-less system, the pressure regulator 7 is provided at the side of the fuel feed
apparatus. The pressure regulator 7 is arranged within the sub-tank 16, and all the
fuel returned from the pressure regulator 7 is fed back to the sub-tank 16. Thus,
the fuel feed apparatus 1 of the present invention is free from the drawback of the
above described known apparatus of returning the fuel 42 in the sub-tank 16 to the
outside of the sub-tank 16 so that it can feed fuel to the engine on a highly stable
basis.
[0033] The discharge port 14 connected to a lower portion of the joint 12 communicates with
a fuel feed port 15 arranged at the bottom of the unit base 4. Thus, the fuel sucked
by the pump 5 is fed to the fuel feed port 15 by way of the cover 11, the strainer
6, the joint 12 and the discharge port 15 and then fed further to the engine by way
of the fuel pipe 43. The flow rate of fuel fed to the pipe 43 is regulated for pressure
by the pressure regulator 7 and any excessive fuel is returned to the sub-tank 16.
[0034] As seen from FIG. 7, the reservoir 4b is provided at the lateral side thereof with
a fuel in-take port 17 for introducing fuel into the sub-tank 16. FIG. 7 is a schematic
lateral view of the apparatus 1 and FIG. 8 is a schematic plan view where the holder
9 and the cover 11 are removed from the apparatus 1. A motor bicycle may frequently
be required to stand on the rear wheel and/or tilt sideways and supported by its prop
stand while being fueled. Additionally, the center of gravity of a motor bicycle moves
to the rear wheel side and it may prance on the rear wheel when accelerated. Still
additionally, the front wheel side of a motor bicycle is higher than the rear side
when it goes up a slope. Under any of these conditions, the engine requires to consume
more fuel than ever. By taking these circumstances into consideration, the port 17
of the apparatus 1 is arranged at a position that does not allow fuel to flow out
when the body of the motor bicycle is tilted or at a position where the port 17 will
face upward when the body of the motor bicycle is tilted. With this arrangement, fuel
is prevented from flowing out of the sub-tank 16 even when the motor bicycle stands
up on the rear wheel or when it prances.
[0035] The front of the body of the motor bicycle will face upward when it stands up on
the rear wheel, whereas the side opposite to that of the prop stand of a motor bicycle
will face upward when the motor bicycle is held standstill and supported by the prop
stand. Thus, the opening 17a of the port 17 of this apparatus 1 is arranged at a position
close to the front end of the body and opposite to the side where the prop stand is
provided so that it may face upward when the front of the motor bicycle faces upward
and hence fuel may be prevented from flowing out under any of the above identified
conditions. Thus, fuel is prevented from flowing out of the sub-tank 16 by way of
the port 17 even when the motor bicycle is made to stand on the rear wheel or tilted
on its prop stand so that the aim of installing the sub-tank 16 may not be devastated
and the engine may be fed with fuel stably and reliably for a long period of time.
[0036] While the location of the fuel port 17 is selected by taking both the situation where
the motor bicycle is made to stand on the rear wheel and the situation where the motor
bicycle is made to rest on its prop stand, it may alternatively be selected by dominantly
taking either of the situations into consideration. If the situation where the motor
bicycle is made to stand on the rear wheel is considered to be the dominant factor,
the port 17 will be arranged at a position close to the front of the motor bicycle.
If, on the other hand, the situation where the motor bicycle is tilted and made to
rest on its prop stand is considered to be the dominant factor, the port 17 will be
arranged at a position opposite to the side of the prop stand.
[0037] The inside of the fuel intake port 17 has a labyrinth structure. More specifically,
as shown in FIGS. 7 and 8, the port 17 is provided with a partition wall 18 extending
peripherally from the opening 17a to the inside of the unit base 4 to produce a labyrinth
19. The wall 18 and the inner wall of the flange 4 define a labyrinth 19. Due to the
provision of the labyrinth 19, the fuel flowing into the sub-tank 16 would not easily
flow out from the tank. Therefore, the selected position of the port 17 and the provision
of the labyrinth 19 minimize the risk of allowing fuel to flow out of the sub-tank
16.
[0038] Meanwhile, a thermistor 24 whose electrical resistance varies as a function of the
ambient temperature is arranged inside the unit base 4 as warning sensor for notifying
the driver with the volume of fuel left in the fuel tank. Generally, the internal
temperature of a fuel tank rises as the amount of fuel stored in it decreases. Therefore,
the thermistor 24 detects the volume of fuel left inside the tank by detecting the
change in the ambient temperature and, when the fuel 42 in the fuel tank goes under
a certain threshold level, it produces a warning by notifying the driver with the
fact that fuel is running out.
[0039] FIG. 9 is a schematic lateral view illustrating how the thermistor 24 is fitted and
wired. As shown in FIG. 9, a negative (grounding) lead wire 25a of the thermistor
24 is branched from a negative lead wire 25b of the pump 5. Additionally, as seen
from FIGS. 2 and 9, the thermistor 24 is secured to the unit base 4 by means of a
thermistor arm (sensor holder) 26 made of an electrically conductive material such
as a metal wire. A grounding wire connecting section 26a is formed on the arm 26 at
a position close to the thermistor 24 and held in electric communication with the
wire 25a. Thus, the arm 26 is connected to the wire 25b by way of the section 26a
and the wire 25a.
[0040] On the other hand, a strainer connecting section 26b is formed on the arm 26 at the
side thereof opposite to the section 26a so that the arm 26 is held in contact with
the outer periphery of the strainer 6 by means of the section 26b. Therefore, the
strainer 26 is connected to the wire 25b by way of the arm 26 and hence grounded through
the arm 26.
[0041] Meanwhile, the outer peripheral wall of the strainer 6 is made of metal or an electrically
conductive resin material in order to allow any static electricity generated by the
fuel passing through the filter member arranged inside and made of paper or resin
to be discharged therefrom. Thus, the static electricity generated in the strainer
6 flows to the wire 25b by way of the arm 26 and the wire 25a. With this arrangement
of the apparatus 1, therefore, the arm 26 is utilized as grounding wire of the strainer
6 so that the thermistor 24 and the strainer 6 share a common grounding wire. In other
words, the grounding wire of the strainer 6 which is otherwise need is omitted and
hence only a single wiring operation is required for grounding the thermistor 24 and
the strainer 6 to consequently reduce the number of parts and also the number of manufacturing
steps.
[0042] It will be appreciated that the above described arrangement can be used not only
for a thermistor but also for a sensor that may alternatively be installed in the
fuel tank with necessary wires. If such is the case, the holder of the sensor will
be made of an electrically conductive material and grounded while it is held in contact
with the strainer 6 in order to discharge static electricity by way of the holder.
[0043] Detailed description has hereinabove been given of the invention achieved by the
present inventor with reference to the embodiments. However, the present invention
should not be limited to the embodiments described above and may be variously modified
within the scope not departing from the gist.
[0044] While the pump 5 and the strainer 6 are mounted to the holder 9 in the above embodiment,
it may alternatively be so arranged that the pressure regulator 7 is arranged upstream
relative to the strainer 6 and the joint 12 is mounted onto the holder 9. Then, the
holder holds the pump 5 and the pressure regulator 7 (joint 12) 9 and the cover 11.
If such is the case, the strainer 6 should not necessarily be arranged within the
fuel tank 2 as in the case of the pressure regulator 7 of the above embodiment.
[0045] Additionally, while the check valve 20 is contained in the cover 11 of the above
described apparatus 1, it may alternatively be arranged downstream relative to the
strainer 6. Then, the strainer 6 may be provided with a gas release hole.
[0046] Still additionally, while the apparatus 1 is fitted to the bottom side of the fuel
tank 2 in the above description, it may be fitted to the top side of the fuel tank
2 like the known apparatus shown in FIG. 10. Furthermore, while the flange 4a and
the reservoir 4b are integrally formed and made to operate as unit base 4 in the above
described apparatus 1, they should not necessarily be integrally formed and, alternatively,
they may be formed separately from each other. The flange 4a may be omitted if the
apparatus 1 is mounted to the top side of the fuel tank 2. Then, the unit base 4 may
take the form of a bottomed sleeve or, alternatively, it may take the form of a sleeve
open both at the top and at the bottom and be fitted to the bottom of the fuel tank
2.
[0047] Additionally, while the present invention is described above in terms of a fuel feed
apparatus of a motor bicycle, the applicability of the present invention is by no
means limited to motor bicycles and it can equally be used as fuel feed apparatus
that is applicable to motor cars, carts for carrying caddy bags in golf courses, lawn
mowers, industrial machines, portable generators and other machines comprising an
internal combustion engine as source of motive power. Still additionally, the fuel
to be used with a fuel feed apparatus according to the invention is not limited to
gasoline but may alternatively be light oil or kerosene oil.
[0048] As described above, since a fuel feed apparatus according to the invention has a
reservoir provided with a fuel in-take port that is so arranged as to face upward
when the body of the motor bicycle or the motor car carrying the apparatus is inclined,
fuel would not flow out of the sub-tank through the fuel in-take port if the body
is inclined for a long period of time so that engine can be fed with fuel stably for
a long period of time.
[0049] If the fuel in-take port so arranged as to face upward when the motor bicycle is
made to rest on the side prop stand or prance on the rear wheel, the motor bicycle
can feed the engine with fuel stably for a long period of time.
[0050] If the inside of the fuel in-take port is made to have a labyrinth structure, the
effect of preventing fuel from flowing out through the fuel in-take port can be further
enhanced.
[0051] Finally, with a fuel feed apparatus according to the invention, the thermistor operating
as sensor for sensing the volume of fuel left in the fuel tank is held by a thermistor
arm made of an electrically conductive material and the thermistor arm is electrically
connected to the strainer at an end and grounded at the other end so that it can be
used as the grounding terminal of the strainer. Then, the thermistor and the structure
share a common grounding terminal to eliminate the grounding wire of the strainer.
Accordingly, both the thermistor and the strainer can be grounded by means of a single
common wire to reduce the number of parts and also that of manufacturing steps.