Internal-combustion engines – Two-cycle – Rear compression
Reexamination Certificate
1999-10-21
2001-01-23
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Two-cycle
Rear compression
C123SDIG005
Reexamination Certificate
active
06176206
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for supplying fuel to a diaphragm-type carburetor, and particularly, to an improvement in a device for supplying fuel to a diaphragm-type carburetor which includes a constant-pressure fuel chamber which communicates at its outlet bore with a lower end of a fuel nozzle through a fuel jet and a check valve, a fuel pump operated in response to a pulsation pressure in a pulsation pressure generating source to feed the fuel to the constant-pressure fuel chamber, and a fuel-introduction control valve for controlling the introduction of the fuel to the constant-pressure fuel chamber by opening and closing an inlet bore in the constant-pressure fuel chamber, wherein a fuel supply passage leading to a fuel tank is connected to an intake side of the fuel pump.
2. Description of the Related Art
The above diaphragm-type carburetor is already known, as disclosed in, for example, Japanese Patent Application Laid-open No.10-131807.
In the diaphragm-type carburetor as described above, a large amount of fuel vapor may be often generated from the fuel fed from the fuel pump toward the constant-pressure fuel chamber during operation of the engine for a long period of time. If the large amount of fuel vapor is ejected at once from the fuel nozzle, the air-fuel ratio of an air-fuel mixture is extremely reduced, thereby causing a disorder in the operation of the engine.
The present inventors have cleared that the cause of generation of a large amount of fuel vapor from the fuel fed from the fuel pump toward the constant-pressure fuel chamber resides in that there is a very large difference in temperature between the diaphragm-type carburetor mounted to the engine and the fuel pumped from the fuel tank to the fuel pump of the carburetor. More specifically, a diaphragm-type carburetor is generally mounted to an engine through an insulator, but the operation of the engine for a long period of time causes the heat generated in the engine to be gradually propagated to the carburetor through the insulator to heat the carburetor. Therefore, if the fuel having a relatively low temperature is introduced from the fuel tank into the carburetor heated to a relatively high temperature, the fuel is heated rapidly, whereby bubbles included in the fuel are expanded suddenly to generate a large amount of fuel vapor.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a device for supplying fuel to a diaphragm-type carburetor mounted to an engine, wherein the difference in temperature between the diaphragm-type carburetor and fuel introduced from a fuel tank into the carburetor can be decreased to inhibit the generation of fuel vapor in the diaphragm-type carburetor.
To achieve the above object, according to the present invention, there is provided a device for supplying fuel to a diaphragm-type carburetor which includes a constant-pressure fuel chamber which communicates at an outlet bore thereof with a lower end of a fuel nozzle through a fuel jet and a check valve, a fuel pump operated in response to a pulsation pressure in a pulsation pressure generating source to feed the fuel to the constant-pressure fuel chamber, and a fuel-introduction control valve for controlling the introduction of the fuel to the constant-pressure fuel chamber by opening and closing an inlet bore in the constant-pressure fuel chamber, a fuel supply passage leading to a fuel tank being connected to an intake side of the fuel pump, wherein the device further includes a fuel transfer means incorporated in an intermediate portion of the fuel supply passage and provided in an insulator which is interposed between the carburetor and the engine.
With this feature, due to the operation of the fuel pump of the diaphragm-type carburetor, in the course of the fuel in the fuel tank reaching the carburetor via the fuel supply passage, the fuel flows via the fuel transfer means in the insulator between the engine and the carburetor. The insulator is heated somewhat by the transfer of heat from the engine during operation of the engine for a long period of time and hence, the fuel flowing via the fuel transfer means in the insulator is also heated suitably. Therefore, the difference in temperature between the fuel exiting from the fuel transfer means and the carburetor heated to a relatively high temperature by the influence of the heat of the engine is decreased and thus, it is possible to avoid a sudden change in temperature of the fuel in the carburetor to inhibit the generation of fuel vapor.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3045605 (1962-07-01), Nutten et al.
patent: 4932370 (1990-06-01), Schierling et al.
patent: 5024188 (1991-06-01), Hartke et al.
patent: 5337710 (1994-08-01), Adam
patent: 5353754 (1994-10-01), Wissmann et al.
patent: 10-131807 (1998-05-01), None
Abe Hitoshi
Ishikawa Hirohisa
Kurasawa Hideo
Honda Giken Kogyo Kabushiki Kaisha
Kintner Arent Fox
Moulis Thomas N.
Plotkin & Kahn PLLC
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