Internal-combustion engines – Charge forming device – Multiple carburetors
Reexamination Certificate
1998-12-18
2001-03-27
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Charge forming device
Multiple carburetors
C440S08800J
Reexamination Certificate
active
06205987
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in a small-sized boat thrust by a jet pump.
2. Description of the Related Art
Generally, a small-sized boat often called “Personal Watercraft” is constructed such that a jet pump disposed in an engine room of a hull is driven by a multicylinder engine to thereby thrust the boat. An example of such a small-sized boat is disclosed, for example, in Japanese Patent Laid-Open Publication No. HEI-7-237587 entitled “Water Sliding Boat” in which rotation of an impeller causes water to jet backwardly to thereby thrust the water sliding boat.
The water sliding boat includes a four-cycle two-cylinder engine within a cowling (an engine room) of a hull thereof. The engine drives the impeller. A crankshaft of the engine is disposed along a line passing through a bow and a stern of the hull. Two intake manifolds are connected to the engine such that they extend transversely of the engine. One carburetor is connected to the intake manifolds.
Generally, for improving output characteristics of a four-cycle multicylinder engine, a carburetor is preferably attached to each cylinder. Also, in order to increase a thrusting force of the impeller of the water sliding boat, it is preferable that a plurality of carburetors are connected to the four-cycle two-cylinder engine.
The cylinders have axes inclined obliquely upwardly. In a small space defined between an inner surface of the cowling and side surfaces opposite from inclined sides of the cylinders, there are disposed a carburetor and a cyclone filter. Difficulty is encountered in disposing a plurality of carburetors in such a small space. More particularly, since a float type carburetor has a float chamber, the carburetor provides limited freedom for disposition in the cowling. Further, the carburetor is made relatively large. Moreover, in the case where the float carburetor is employed, a float sways when the hull pitches and rocks. Thus, care should be taken to keep stable output characteristics of the engine.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a small-sized boat which allows easy attachment of a carburetor to each cylinder of a multicylinder engine disposed in a small engine room thereof and which enables the maintenance of stable output characteristics of the engine even when a hull thereof pitches and rocks.
According to an aspect of the present invention, there is provided a small-sized boat thrust by a jet pump, which comprises: a multicylinder engine disposed in an engine room of a hull for driving the jet pump, the multicylinder engine having a crankshaft axis disposed along a line extending through a bow and a stern of the hull; a plurality of diaphragm carburetors including shafts for throttle valves each provided vertically in correspondence to the number of cylinders of the engine, one throttle link connected to upper parts of the shafts for the throttle valves, and a plurality of diaphragm mechanisms having operating surfaces perpendicular to the crankshaft axis; and a fuel supplying pipe disposed below the carburetors in parallel with the crankshaft axis.
Preferably, the plurality of diaphragm carburetors are assembled together to form a single body. In other words, the diaphragm type carburetor is smaller in size than a carburetor having a float chamber. Thus, the diaphragm carburetor can be relatively freely disposed in the engine room as compared to other carburetors having a float chamber. Such plural diaphragm carburetors may be linked together to form a single body of carburetors. In particular, the shafts for the throttle valves, the operating surfaces of the diaphragm mechanisms, and the fuel supplying pipe are reasonably disposed in the engine room. Therefore, the carburetor assembly is made small.
Consequently, it becomes possible to attach each carburetor in correspondence to each cylinder of the multicylinder engine disposed in the small engine room of the small-sized boat.
Because the carburetor assembly is made small in the manner as described above, respective intake passages of an intake manifold connected to the engine can have substantially the same configuration, whereby the amount of air introduced into each cylinder can be uniform to thereby provide an output of the multicylinder engine steadily.
Since the diaphragm type carburetor is employed in the present invention, it becomes possible to steadily control an the amount of fuel supplied to the engine even when the hull of the small-sized boat pitches and rocks, thereby attaining a steady output of the engine.
Furthermore, the carburetors of the present invention include shafts for choke valves each provided vertically and one choke link connected to upper parts of the shafts for the choke valves through levers each provided on the shaft for the choke valve.
The diaphragm mechanism may comprise a case body, a lid, a diaphragm chamber formed by the case body and the lid, a diaphragm for separating the diaphragm chamber into a reference pressure chamber and a pressure applying chamber, a swing arm pivotably mounted in the pressure applying chamber with one end thereof located centrally of the diaphragm, a compression spring for urging the one end of the swing arm toward the diaphragm, a valve body for attaching the other end of the swing arm thereto, and a valve seat opened and closed by the valve body.
REFERENCES:
patent: 2313258 (1943-03-01), Olson
patent: 3742922 (1973-07-01), Hisatomi et al.
patent: 4532904 (1985-08-01), Osawa et al.
patent: 5517977 (1996-05-01), Nakai et al.
patent: 5676887 (1997-10-01), Soeda et al.
patent: 5718204 (1998-02-01), Sugii
patent: 5732685 (1998-03-01), Nakamura
patent: 5921225 (1999-07-01), Nakamura
Fujita Yasushi
Funai Hiroshi
Shigedomi Hideo
Adams & Wilks
Honda Giken Kogyo Kabushiki Kaisha
Kamen Noah P.
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