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BACKGROUND OF THE INVENTION
The present invention relates to a fuel pump unit of a motorcycle.
In a motorcycle, a mixture air is supplied to an engine by using a
carburetor or, in an improvement, a fuel is injected into an intake
passage of a throttle body connecting an air cleaner to an engine by using
an injector. In the case of the fuel injection system, it is necessary to
arrange a fuel pump for pressurizing the fuel, for example, in a fuel tank
(refer to Japanese Patent Laid-Open Publication No. HEI 5-99089), or the
pump is mounted, for example, to a body frame outside the fuel tank (refer
to Japanese Patent Laid-Open Publication No. SHO 57-191173).
By the way, in the case where a discharge pressure of a fuel pump increases
to a predetermined value or more, normally, a pressure regulator provided
on the most downstream side of a fuel flow passage is opened to restore
the excessive fuel into the fuel tank.
However, in the case of providing the fuel pump in the fuel tank, a wide
place for installing the fuel pump is necessary in the tank, especially at
the bottom surface of the tank, and a shape or a layout of the fuel tank
is limited.
Furthermore, a high sealing performance is required between the bottom
surface of the fuel tank and the installation surface of the fuel pump.
However, the fuel tank is generally made of a steel sheet, and therefore,
it is difficult to realize a high sealing performance.
Moreover, when the fuel pump is provided in the fuel tank, the capacity of
the tank is reduced.
On the other hand, in the case of arranging the fuel pump outside the fuel
tank, although the fuel pump is attached to a part of the body frame, it
is necessary to use a high pressure hose for connecting the fuel pump and
the throttle body, and therefore, it is undesired to widen the distance
between the fuel pump and the throttle body.
That is, when the high pressure hose becomes longer, it becomes difficult
to keep the air tightness, it becomes necessary to wind a protector or the
like around the outer surface of the hose, and the layout becomes complex
so as not to interfere with other parts, providing many problems.
In a case where the fuel pump can be arranged near the throttle body, the
high pressure hose becomes shorter, but there are many cases where other
equipments are attached to the body frame near the throttle body.
Therefore, in some cases, it is difficult to mount the fuel pump .
Furthermore, when the fuel pump is attached to the body frame near the
throttle body, it is necessary to simultaneously remove the fuel pump when
removing the engine or the throttle body (since the high pressure hose is
short), which results in a bad maintenance performance.
On the other hand, in a pump for feeding fuel, when the fuel pump is
positioned above the fuel outlet of the fuel tank, it is necessary for the
fuel pump to simultaneously suck the fuel, and the load on the pump is
increased as the difference in location levels becomes larger. As a
result, there is a possibility that the fuel cannot stably be supplied,
and there is also a possibility that the pump becomes large-sized for the
stable supply of the fuel.
Moreover, when the pressure regulator is provided on the most downstream
side of the fuel flow passage, the piping becomes long and complex, thus
being inconvenient.
SUMMARY OF THE INVENTION
An object of the present invention is to substantially eliminate defects or
drawbacks encountered in the prior art mentioned above and to provide a
fuel pump unit of a motorcycle capable of making short a high pressure
hose and providing a high maintenance performance.
This and other objects can be achieved according to the present invention
by providing a fuel pump unit of a motorcycle in which an engine is
arranged at a lower portion of substantially a center portion of a
motorcycle body between a front wheel and a rear wheel and a fuel tank is
arranged above the engine, wherein the engine is formed, at a rear portion
thereof, with an intake port to which an air-fuel mixture supply means is
connected and a fuel pump for supplying fuel in the fuel tank to the
air-fuel mixture supply means is attached integrally to the air-fuel
mixture supply means.
In a preferred embodiment, the engine has a plurality of cylinders to which
the intake ports are formed, respectively, and the air-fuel mixture supply
means is connected to the intake port formed to each cylinder. A plurality
of air-fuel mixture supply means are integrally connected by a connection
plate and the fuel pump is mounted integrally to the air-fuel mixture
supply means through a stay extending from the connection plate.
The air-fuel mixture supply means has a fuel injection type structure. The
air-fuel mixture means is disposed between a lower portion of the fuel
tank and the upper portion of the engine and comprises a throttle body
provided with a fuel injector. The fuel pump is provided with a pressure
regulator to regulate a pressure of the fuel and then to supply a fuel to
the air-fuel mixture supply means.
The engine has a plurality of cylinders to which the intake ports are
formed and the fuel pump is arranged so that a longitudinal axis thereof
is arranged substantially in parallel with a row of the plurality of
cylinders. The engine may have a plurality of cylinders to which the
intake ports are formed and the fuel pump is arranged so that a
longitudinal axis thereof is arranged substantially in parallel with an
axis of the plurality of cylinders, the fuel pump being arranged so that a
fuel inlet thereof is positioned to a lowermost position. Furthermore, the
engine may have a plurality of cylinders to which intake ports are formed
and the fuel pump is arranged so that a longitudinal axis thereof is
arranged substantially at right angles with a row of the plurality of
cylinders, the fuel pump being arranged so as to be inclined backward
downward so that a fuel inlet thereof is positioned to a lowermost
position.
According to the fuel pump unit of a motorcycle of the present invention of
the characters mentioned above, in the motorcycle, the engine is arranged
at the lower portion of the center of the motorcycle body between the
front wheel and the rear wheel and the fuel tank is arranged above the
engine. The air-fuel mixture supply means is connected to the intake port
formed at the rear portion of the engine. In addition, the fuel pump for
supplying the fuel is attached integrally to the mixture supply means.
Therefore, the shape and layout of the fuel tank are not specifically
limited, and the inner volume of the fuel tank can be kept properly, and
it is also not necessary to consider the sealing performance between the
fuel tank and the fuel pump. Furthermore, the high pressure hose for
connecting the mixture supply means and the fuel pump can be made short.
Moreover, the mixture supply means and the fuel pump can be unitized, and
the performance of maintenance can be improved.
Still furthermore, the engine has a plurality of cylinders, and the mixture
supply means is connected to each of the intake ports formed to each
cylinder. The mixture supply means are integrally connected by a
connection plate, and the fuel pump is attached integrally to the mixture
supply means through the stay integrally extending from the connection
plate. Therefore, the mixture supply means and the fuel pump are unitized,
and the performance of maintenance can be improved thereby to increase the
degree of freedom in the installation position and direction of the fuel
pump.
Furthermore, the fuel mixture supply means is a fuel injection type, which
is constituted so that a pressure regulator is provided in the fuel pump
and the fuel is supplied to the mixture supply means after regulating the
pressure of fuel in advance. Therefore, a long complex piping is
unnecessary, and the amount of the fuel injection is also made stable.
Still furthermore, since the fuel pump is arranged so that a longitudinal
axis thereof is almost in parallel with a row of the plurality of
cylinders, the space behind and under the fuel pump can be expanded.
Still furthermore, the fuel pump is arranged so that a longitudinal axis
thereof is almost in parallel with an axis of the plurality of cylinders
and the fuel pump is arranged so that a fuel inlet thereof is arranged at
the lowermost position. Therefore, the space behind the fuel pump can be
expanded, and a stable fuel supply can be realized.
Still furthermore, the fuel pump is arranged so that a longitudinal axis
thereof is arranged at right angles with a row of the plurality of
cylinders and the fuel pump is arranged to the lower backward position so
that the fuel inlet thereof is arranged at the lowermost position.
Therefore, the space under the fuel pump can be also expanded and a stable
fuel supply can be also realized. The vapor lock of the fuel can be
prevented, and further, the fuel hose connecting the fuel tank and the
fuel pump can be shortened.
The nature and further characteristic features of the present invention
will be made more clear from the following descriptions made with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is a left side view of a motorcycle provided with a fuel pump unit
of a motorcycle according one embodiment of the present invention;
FIG. 2 is a left side view of a central portion of a motorcycle body with a
cowling thereof being removed (first arrangement example of a fuel pump
unit);
FIG. 3 is a left side view of a throttle body and a fuel pump;
FIG. 4 is a plan view of the throttle body and the fuel pump;
FIG. 5 is a rear side view of the throttle body and the fuel pump;
FIG. 6 is a cross sectional view taken along the line VI--VI in FIG. 4;
FIG. 7 is a cross sectional view of the fuel pump taken along the line
VII--VII in FIG. 3;
FIG. 8 is a left side view of the central portion of a motorcycle body
showing a second arrangement example of a fuel pump unit; and
FIG. 9 is a left side view of the central portion of a motorcycle body
showing a third arrangement example of a fuel pump unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention will be described hereunder with
reference to the accompanying drawings.
FIG. 1 is a left side view showing one example of a motorcycle to which the
present invention is applicable. With reference to FIG. 1, the motorcycle
1 has a body frame 2 and a head pipe 3 provided in front of the body frame
2. In the head pipe 3, a suspension mechanism, not shown, is located, and
a steering mechanism 6 constituted from a pair of left and right front
forks 5 which rotatably support a front wheel 4 or the like is also
provided.
On the other hand, the body frame 2 is, for example, a frame having a
twin-tube structure, which comprises a pair of left and right tank rails 7
extending in parallel with each other diagonally backward and downward
after being expanded in the lateral direction just behind the head pipe 3,
a pair of left and right center frame members 8 connected to the rear end
portions of the tank rails 7 so as to extend almost vertically, and a pair
of left and right seat rails 9 extending backward from the rear upper ends
of the center frame members 8.
A fuel tank 10 is arranged above the tank rails 7, and a rider's seat 11 is
arranged above the seat rails 9. Furthermore, at the lower portions of the
center of the center frames 8, is mounted a pivot (shaft) 12 to which
swing arms 13 are pivoted so as to be freely swingable thereabout.
Further, at the rear ends of the swing arms 13, a rear wheel 14 is
rotatably supported.
In this motorcycle 1, the front portion of the body is covered by a cowling
15 having a streamline shape to reduce an air resistance caused at a time
of running and to protect the rider from the wind pressure while running.
FIG. 2 is a left side view of the central portion of the motorcycle body in
the state where the cowling 15 is removed. As shown in FIG. 1 and FIG. 2,
an engine or engine unit 16 is arranged at the lower portion of the center
of the motorcycle body between the front and rear wheels 4 and 14 under
the fuel tank 10. This engine 16 is, for example, a water-cooling type
parallel four cylinder engine, and four cylinder assemblies 17 (hereunder,
which may be called merely cylinders or cylinder assembly) are arranged in
the width direction of the motorcycle body in the state of being slightly
inclined forward at the upper portion of a crankcase 18. Furthermore, a
radiator 19 for cooling the engine 16 is arranged in front of the engine
16 under the head pipe 3.
To each of the cylinder assemblies 17, an air-fuel mixture supply means
(hereunder, may be called mixture supply means) is connected. The mixture
air supply means used in this motorcycle 1 is a means of a fuel injection
type having a throttle body 21 as a main component thereof provided with a
fuel injector 20. The mixture air supply means is arranged between the
lower portion of the fuel tank 10 and the upper portion of the engine 16
and provided with an air cleaner 22 connected on the upstream side of each
throttle body 21 and a fuel pump 23 for forcibly feeding the fuel in the
fuel tank 10 to the fuel injector 20.
With reference to FIGS. 2 to 5, an intake port 25 is formed for each of the
cylinder assemblies 17 at the rear portion of a cylinder head 24 provided
at the upper portion of each cylinder assembly 17, and the throttle body
21 provided with the fuel injector 20 is connected to each intake port 25.
The throttle bodies 21 are integrally connected by means of a connection
plate 26 as shown in FIG. 5.
Furthermore, as shown in FIG. 6, each throttle body 21 has a throttle valve
27 disposed in an intake passage thereof, and on the down stream side of
the throttle valve 27, the fuel injector 20 for directly injecting the
fuel is integrally mounted. The fuel pump 23 is arranged behind the
throttle body 21 through a stay 28 integrally extending from the
connection plate 26.
As shown in FIG. 2, a fuel outlet 29 is provided near the lowermost portion
of the fuel tank 10, and the fuel in the fuel tank 10 is guided to the
fuel pump 23 through a fuel hose 31 from a fuel cock 30 provided at this
outlet 29.
Next, with reference to FIG. 7, a motor 32 and a pump means 33 such as an
impeller driven by this motor 32 are contained in the fuel pump 23, and
through the operation of the pump means 33, the fuel in the fuel tank 10
is guided into a suction (in-take) chamber 35 in the fuel pump 23 from a
fuel inlet 34 provided on one side of the fuel pump 23, for example, on
the right side in FIG. 7. Then, the fuel in the suction chamber 35 is
forcibly fed to the other side of the fuel pump 23, for example, to the
left side in FIG. 7 by the pump means 33, and after being filtered by a
filter 36, the fuel is guided to each fuel injector 20 through a high
pressure hose 37 as shown by white arrows in FIG. 7.
Between the pump means 33 in the fuel pump 23 and the filter 36, a pressure
regulator 38 is provided, which is constituted so that when the fuel
discharge pressure of the pump means 33 rises to a predetermined value or
more, the pressure regulator 38 is opened and the excessive fuel is
restored in the fuel tank 10 through a return passage 39 and a return hose
40 (refer to FIG. 2) to keep the pressure of fuel constant. Furthermore,
between the pump means 33 and the pressure regulator 38, a check valve 41
is also provided, which is constituted so that the excessive fuel does not
flow back to the pump means 33 side.
Hereunder, the arrangement of the fuel pump unit will be described.
In a first arrangement, as shown in FIG. 2 to FIG. 5, the fuel pump 23 is
arranged so that a longitudinal axis 42 thereof is at right angles with a
row 43 of the cylinder assemblies 17 (refer to FIG. 4,) and the fuel pump
23 is arranged to a lower backward portion so that the fuel inlet 34
thereof is positioned near the fuel outlet 29 at the lowermost portion of
the fuel tank 10 and below the fuel outlet 29.
In a second arrangement of the fuel pump, as shown in FIG. 8, the fuel pump
223 is arranged so that a longitudinal axis 242 thereof is almost in
parallel with an axis 44 of the cylinder assembly 17, and the fuel pump
223 is arranged so that a fuel inlet 234 thereof is positioned at the
lowermost portion.
In a third arrangement of the fuel pump unit, as shown in FIG. 4 and FIG.
9, the fuel pump 323 is arranged so that a longitudinal axis 342 thereof
is almost in parallel with a row 43 of the cylinder assemblies 17 (refer
to the two-dot chain line in FIG. 4).
Next, the operation of the fuel pump of present embodiment will be
described.
Since the fuel pump 23 is not arranged inside the fuel tank 10 but is
arranged outside the fuel tank 10, the shape of the fuel tank 10 and the
layout are not limited, and the inner volume of the fuel tank 10 is not
decreased, and it is also unnecessary to consider the sealing performance
between the fuel tank 10 and the fuel pump 23.
Furthermore, since the fuel pump 23 is arranged behind the throttle body
21, the high pressure hose 37 can be made short, and the air tightness in
the fuel pump 23 can easily be kept. Furthermore, the layout of the high
pressure hose 37 is made also simple, and in addition, the total cost can
be reduced.
Furthermore, a plurality of throttle bodies 21 are integrally connected by
the connection plate 26 and the fuel pump 23 is attached to the throttle
bodies 21 through the stay 28 integrally extending from the connection
plate 26, so that the throttle bodies 21 and the fuel pump 23 are unitized
thereby to effectively improve the performance of maintenance thereof.
Still furthermore, since the fuel pump 23 is not attached to the body
frame 2 but is attached to the throttle body 21, the body frame 2 can be
made light-weight, and the degree of mounting freedom is hence increased
in the installation position and direction of the fuel pump 23, and it is
also possible to compensate or correct the weight balance of the engine 16
by the change of the installation position of the fuel pump 23.
Still furthermore, since the pressure regulator 38 is arranged in the fuel
pump 23 to supply the fuel to the injector 20 after regulating the
pressure of the fuel in advance, the long complex piping, which has been
required in the prior art, becomes unnecessary, and in addition, the
amount of the injection fuel is made stable and the lifetime of the fuel
injector 20 is made long.
Incidentally, since the fuel pump 323 is arranged so that a longitudinal
axis 342 thereof is made almost parallel with a row 43 of the cylinder
assemblies 17, the space behind and under the fuel pump 323 is expanded,
and the degree of freedom for the mounting is hence increased in the shape
of the fuel tank 10, and in addition, the degree of freedom in the layout
of the upper surface of the crankcase 18 (for example, of a breather
chamber or a starter motor, not shown) is also increased.
Furthermore, since the fuel pump 223 is arranged so that a longitudinal
axis 242 thereof is made almost parallel with an axis 44 of the cylinder
assemblies 17, the space behind the fuel pump 223 is expanded, and the
degree of freedom is hence increased in the shape of the fuel tank 10, and
in addition, the fuel inlet 234 of the fuel pump 223 can be arranged in
the lowermost position, and as a result, the fuel inlet 34 is positioned
below the fuel outlet 29 of the fuel tank 10, and the suction chamber 35
of the fuel pump 223 is filled up with the fuel at all times, and
therefore, the fuel can stably be supplied even though the output of the
motor 32 of the fuel pump 223 is small.
Furthermore, since the fuel pump 23 is arranged so that a longitudinal axis
42 thereof is arranged at right angles with a row 43 of the cylinder
assemblies 17, the space under the fuel pump 23 is expanded, and the
degree of freedom in the layout of the upper surface of the crankcase 18
is therefore increased. In addition, the fuel inlet 34 of the fuel pump 23
is arranged at the lowermost position, and as a result, the fuel inlet 34
is positioned below the fuel outlet 29 of the fuel tank 10, and the fuel
can stably be supplied even though the output of the motor 32 of the fuel
pump 23 is small. Furthermore, since the fuel inlet 34 of the fuel pump 23
goes away from the cylinder assembly 17, the vapor lock of the fuel in the
fuel inlet 34 due to the heat transferred from the engine 16 can be
prevented, and the hose 31 connecting the fuel inlet 34 and the fuel cock
30 can be made short.
Incidentally, in the above embodiments, the example in which the fuel pump
23 is used in a four cylinder engine 16 has been shown, but the fuel pump
23 according to the present invention may be applied to a single cylinder
engine, a two cylinder engine or the like regardless of the number of
cylinders of an engine.
It is to be noted that the present invention is not limited to the
described embodiments and many other changes and modifications may be made
without departing from the scopes of the appended claims.
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