Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE IN~ENTION
SYSTEM FOR OPERATING TWO-CYCLE SPARK IGNITION ENGINE
BACKGROUND OF THE INVENTION
The present invention relates to an operating system
that is applied to an emergency pump unit, which is used as
a fire pump or a drain pump in vessels, for example, the
system enabling a two-cycle spark ignition engine, which is
used to operate such an emergency pump unit, to be operated
with ~as oil.
1~ A typical conventional emergency pump unit that is used
as a fire pump or a drain pump in vessels employs a two-
cycle spark ignition engine that uses gasoline as fuel.
This is because such a two-cycle spark ignition engine is
light in weight and small in size in comparison to other
1~ types of engine, for example, diesel engines, and it is
therefore suitable for a fire pump from the viewpoint of
startability and portability. The prior art suffers,
however, from the problems that vessels must have gasoline
always ready on hand, and the prior art is lnferior in
~0 safety.
If a two-cycle spark ignition engine is designed to use
~uel other than gasoline in order to solve the above-
described problems, it will become difficult to start the
en~ine. In Japanese Patent Public Disclosure (Laid-Open)
~S No. 60-62649 (1985), for example, kerosene is used as fuel
and supplied in such a way thatj only when the engine is to
be started, kerosene is atomized by use of an ultrasonic
atomizer that comprises a vibrating plate, and when the
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engine is running in a steady state, the kerosene is
supplied through a carburetor. In this system, however,
since the ultrasonic atomizer comprises a vibrating plate,
the flow rate of atomized fuel is low, so that the
ultrasonic atomizer can be used only at the time of starting
the engine, and it is impossible to use a gas oil that is
heavier than kerosene.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a
1~ system for operating a two-cycle spark ignition engine of an
emergency pump unit that is suitable for use in vessels,
which enables such a two-cycle spark ignition engine to be
operated with gas oil by use of an ultrasonic atomizer,
thereby solving the above-described problems of the prior
~rt.
It is another object of the present invention to
achieve a stable engine running and reduce the emission of
smoke when a gas oil is used in a two-cycle spark ignition
engine.
~0 To these ends, the present invention provides a system
for operating a two-cycle spark ignition engine, which
comprises an ultrasonic atomizer that is disposed in an
intake pipe of the spark ignition engine, the ultrasonic
a~omizer having a cylinder, a fuel passage that is formed in
~5 the cylinder, and a vibrating member that is disposed inside
the cylinder, wherein, when the engine is to be started, a
fuel for starting is supplied to the vibrating member of the
ultrasonic atomizer, and after the engine has been started,
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a gas oil is supplied to the vibrating member of the
ultrasonic atomizer, thereby atomizing and spraying the gas
oil into the intake pipe.
Examples of fuel for starting are gasoline distillate
and other substances which are liquid in an ordinary state
and which have a flash point equal to that of gasoline
distillate, i.e., highly flammable chemical products, e.g.,
naphtha, thinner, ether, etc.
The feature of the present invention resides in that
the ultrasonic atomizer is disposed in the intake pipe to
atomize fuel. However, a carburetor may be employed in
addition to the ultrasonic atomizer so that, when the engine
is to be started, a fuel for starting is supplied to the
carburetor, and after the engine has been started, a gas oil
is supplied to the ultrasonic atomizer to atomize and spray
it into the intake pipe. It is also possible to employ a
battery at the time of starting the engine.
According to the present invention, it is possible to
increase the amount of fuel atomized and sprayed by the
ultrasonic atomizer and improve the combustibility. In
consequence, it is possible to realize combustion of gas oil
in a two-cycle spark ignition engine and hence possible to
reduce the weight, lower the fuel cost and ensure safety.
Thus, the present invention provides an emergency pump unit
which is particularly suitable for use in vessels.
~RIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a sectional view of one embodiment of a two-
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cycle spark ignition engine, showing the two-cycle spark
ignition engine operating system according to the present
invention;
Fig. 2 is a sectional view of the ultrasonic atomizer
shown in Fig. l;
Fig. 3 is a sectional view of a fuel supply section,
showing another embodiment of the two-cycle spark ignition
engine;
Fi~. 4 is a graph showing the relationship between the
throttle opening and the flow rate of fuel, for explanation
o~ the uel supply method in the arrangement shown in
Fig. 3; and
Fig. 5 is a side view of one embodiment of an emergency
pump unit to which the present invention is applied.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be described
below with reference to the accompanying drawings.
Fig. 5 shows an emergency pump unit 1 to which the
present invention is applied. The emergency pump unit 1
comprises a frame 2r a two-cycle spark ignition engine 3
that is secured to the frame 2, and an emergency pump 4 that
is also secured to the frame 2. The two-cycle spark
ignition engine 3 has an intake pipe 5, a carburetor 6, an
ultrasonic atomizer 7, an oscillator 8, a throttle lever 9
~5 with an overrotation preventing mechanism, a recoil type
hand starter 10, and a muffler 11. The emergency pump 4 is
connected with a vacuum pump 13 which is in turn connected
to an output shaft of the two-cycle spark ignition engine 3
through a V-belt.
The emergency pump unit 1 having the above-described
arrangement is operated as follows. By pulling the handle
lOa of ~he recoil type hand starter 10, the two-cycle spark
i~nition engine 3 is started and the vacuum pump 13 is
activated through the V-belt to suck water into the
emergency pump 4~ Thereafter, the vacuum pump 13 is
suspended, and with a handle 12 opened, the throttle lever 9
is operated to fully open the throttle valve, thereby
1~ performing a rated load opexation.
Fig. 1 is a sectional view of one embodiment of the
t~o-cycle spark ignition engine 3. In this embodiment,
neither carburetor nor throttle lever is employed.
The two-cycle spark ignition engine 3 has an upper
c~linder 15 and a lower cylinder 16, in each of which a
piston 18 that is connected to a connecting rod 17 is
disposed to define a combustion chamber 19, and an ignition
plug 20 is disposed to face the combustion chamber 19. In
addition, a crankshaft 21 that enables the connecting rods
17 to perform reciprocating motion is disposed through an
upper crankcase 22 and a lower crankcase 23. The upper and
lower crankcases 22 and 23 are connected to the intake pipe
5 throu~h respective reed valves 24 and 25. In the intake
pipe 5 are disposed the above-described ultrasonic atomizer
7 and an air cleaner 26.
The ultrasonic atomizer 7 has a vibrating member 28
that is disposed in a cylinder 27, which is slantingly
attached to the intake pipe 5 so that the forward end of the
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cylinder 27 extends into the intake pipe 5 and faces the
reed valves 24 and 25. The distal end portion of the
cylinder 27 is formed with an annular fuel passage 30 (see
Fig. 2) that is connected to a fuel supply pipe 29. In
operation, a signal that is output from the oscillator 8
(see Fig. 5) is converted into ultrasonic vibration in an
electroacoustic transducer 31 to atomize the fuel that is
supplied to an atomizing portion 28a of the vibrating member
~ from the fuel supply pipe 29 through the fuel passage 30,
ld thereby spraying fuel droplets into the intake pipe 5.
The operating system of the embodiment arranged as
described above will next be explained. When the two-cycle
spark ignition engine 3 is to be started, a small amount of
gasoline is supplied to the vibrating member 28 of the
ultrasonic atomizer 7 from the fuel supply pipe 29, and the
gasoline that is atomized by ultrasonic vibration at the
atomizing portion 28a is supplied to the combustion chambers
19 through the intake pipe 5~ reed valves 24, 25 and the
upper and lower crankcases 22 and 23. After the engine has
been started, gas oil is supplied to the vibrating member 28
~rom the fuel supply pipe 29 and atomized by ultrasonic
vibration, thereby spraying the atomized gas oil into the
intake pipe 5.
Fig. 3 shows another embodiment of the present
~S invention, in which an air filter 26, a carburetor 6, a
throttle valve 32 and an ultrasonic atomizer 7, which is
similar to that shown in FigO 2, are disposed in the intake
pipe 5 in the mentioned order from the upstream side, the
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throttle valve 32 being linked to the throttle lever 9 shown
in Fig. 5.
The carburetor 6 comprises a float chamber 33, a float
34, a fuel supply pipe 35, a nozzle pipe 36 and an air
S bypass pipe 37 for generating a differential pressure. The
distal end of the nozzle pipe 36 is opened into a venturi
portion 38 that is formed in the intake pipe 5. Through the
fuel supply pipe 35, a fuel of excellent ignitionability,
e.~., gasoline, is supplied to the float chamber 33. The
la supply of the fuel is controlled to a predetermined level by
means of the float 34. Since the level of negative pressure
at the venturi portion 38 increases as the degree of opening
of the throttle valve 32 increases, gasoline is sprayed into
the intake pipe 5 from the nozzle pipe 36 at a flow rate
lS that is proportional to the level of negative pressure. On
the other hand, the ultrasonic atomizer 7 is supplied with a
gas oil from a fuel pump (not shown).
A method of supplying fuel to the two-cycle spark
ignition engine shown in Fig. 3 will next be explained with
reference to Fig. 4.
At the time of starting the engine, while the opening
of the throttle valve 32 is small, the supply of a gas oil
~rom the ultrasonic atomizer 7 is stopped, but a fuel of
excellent ignitionability, e.g., gasoline, is supplied
~S instead in such a manner that the fuel flow rate increases
as the throttle opening increases, as shown by the curve A
in Fig. 4. ~hen the throttle opening reaches a
predetermined value el after the engine has been started,
the gas oil is supplied from the ultrasonic atomizer 7, as
shown by the curve B in the figure, and at the same time,
the supply of the gasoline fuel is gradually reduced and
eventually suspended. It should be noted that the supply of
fuel from the ultrasonic atomizer 7 may be increased
stepwisely, as shown by the curve C in the figure. The
control of the gasoline fuel is effected by means of a
control valve that is provided in the nozzle pipe 36 or the
air bypass pipe 37.
la Incidentally, spark ignition engines which are supplied
with gasoline and a gas oil involve the problem that an
engine trouble occurs if fuel is supplied at a flo~ rate
which is necessary for a rated load operation before this
state is reached. More specifically, if gas oil is supplied
through the carburetor 6 at the time of starting the engine,
as the throttle opening increases, an excessive amount of
fuel is supplied from the float chamber 33 of the carburetor
6, which invites an engine trouble and an increase in the
emission of smoke.
~ccording to the above-described embodiment, a fuel of
excellent ignitionability, e.g., gasoline, is supplied from
the carburetor 6, and a gas oil from the ultrasonic atomizer
7, so that it is possible to achieve a stable engine running
and reduce the emission of smoke.
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