JPS624685Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention has a fuel pump that performs pumping action using pulsating pressure generated during engine operation, is formed in the carburetor body, and a fuel tank installed at a higher position than the carburetor. This invention relates to a carburetor in which a fuel pot for opening and closing a fuel passage leading to a fuel chamber of the carburetor is formed in the pump cover of the fuel pump.

In general, carburetors and fuel tanks used in small general-purpose engines such as chain saws and brush cutters are desired to have a simple structure and compact design with no waste in order to reduce the cost. For example, by making the diameter of the fuel passage formed in the valve body of a fuel tank as small as possible within a range that does not interfere with the maximum fuel flow rate of the carburetor, the valve body and valve seat surface can be Since the sealing area increases and the sealing effect improves,
Accordingly, the shape of the valve body and the valve body housing chamber constituting the valve seat surface can be reduced within the range where a sealing effect can be obtained, and the entire fuel tank can be made more compact. However, when the fuel pot is installed at the bottom of the fuel tank, if the diameter of the fuel passage of the valve body becomes smaller than the diameter of the fuel passage connecting the fuel pot and the fuel chamber of the carburetor, the fuel If bubbles occur in the fuel passage downstream of Kotuku,
The bubbles rise inside the fuel passage, but the small diameter of the fuel passage formed in the valve body becomes an obstacle.
The fuel cannot be discharged into the fuel tank, and as bubbles remain, the supply of fuel from the fuel tank to the fuel chamber of the carburetor is stopped. In order to eliminate such fuel shortages, a fuel pump that is activated by the pulsating pressure generated during engine operation is attached to the carburetor, and the fuel in the fuel tank is forcibly fed to the fuel chamber of the carburetor. If the bubbles generated in the fuel passage that connects the fuel tank to the fuel pump from the fuel tank installed at the bottom of the fuel tank cannot be discharged to the fuel tank and remain in the fuel passage downstream of the fuel tank, the fuel pump The flow rate of fuel that is forcibly supplied to the fuel chamber of the carburetor and supplied to the engine from the fuel chamber of the carburetor may change inadvertently, causing malfunctions such as fluctuations in engine rotation. There is.

The present invention was developed in view of the above-mentioned drawbacks, and a fuel pump is formed by connecting a high-positioned fuel tank with a fuel passage, and a pump cover attached to a part of the main body with a check valve and a pump membrane in between. The carburetor is characterized in that a fuel pot for opening and closing the fuel passage is installed on the pump cover, and the fuel passage is configured to be straight when the fuel pot is opened.

To explain the figures below, A is the fuel tank installed higher than the carburetor B, 1 is the carburetor main body, 2 is the intake passage, 3 is the throttle valve, and 4 is the fuel nozzle that opens on the bottom wall of the intake passage 2. , 5 is a diaphragm having a fuel chamber 6 on its upper side and an atmospheric chamber 7 on its lower side. 8
1 is a fuel pump provided integrally with the carburetor main body 1. To explain its configuration in detail, a recess 9 formed on the carburetor main body 1 side and a recess 11 formed on the pump cover 10 side are connected to a pump diaphragm 12. Of the two chambers thus formed, one chamber is a pump chamber 13 and the other chamber is a pulsating pressure chamber 14, and the pump chamber 13 has a discharge side port 1.
5. A suction side port 16 is bored, and one end of the discharge side port 15 is connected to the fuel chamber 6 via a discharge valve 18.
It communicates with a fuel passage 17 that opens to. Further, the suction side port 16 communicates with a fuel passage 20 that opens into the fuel tank A at one end via a suction valve 21. 22 is the fuel passage 1 in conjunction with the diaphragm 5.
7 is a needle valve that opens and closes. The above is the configuration of a conventionally commonly used vaporizer.

In the present invention, a fuel cock 23 for opening and closing the fuel passage 20 is provided integrally with the pump cover 10, and a valve chamber 24 is formed orthogonally to the fuel passage 20, and a valve body 25 is installed in this valve chamber 24. By accommodating the carburetor and operating the valve body 25 from outside the carburetor, the fuel passage 20 is opened and closed just before the intake valve 21 of the fuel pump 8. Furthermore, when the fuel pot 23 is opened, the fuel passage 20 on the pump cover 10 is formed to be straight, and air bubbles are generated in the fuel passage between the fuel pot 23 and the intake valve 21 of the fuel pump. The fuel tank A is designed to promptly discharge the fuel into the fuel tank A. Note that 24a is a valve seat, and 25a is a lever.

In the carburetor configured as described above, a manual fuel pot 23 is installed on the fuel passage 20 connecting the fuel tank A and the fuel pump 8 formed in the carburetor body 1.
In this configuration, the fuel passage 20 between the fuel tank A and the fuel tank 23 can be made long, and the fuel passage 20 between the fuel tank 23 and the fuel pump 8, which has a small diameter part, can be shortened. Bubbles generated in the long fuel passage 20 between the fuel tanks 23 are quickly discharged into the space above the fuel tank A, and
Fuel passage 20 between fuel tank 23 and fuel pump 8
is extremely short, so that the fuel in the fuel passage 20 reaches the fuel pump chamber 8 before generating bubbles.
The fuel is quickly drawn in and fed to the fuel chamber 6 of the carburetor. In addition, even if bubbles occur, the Fuel Kotoku 23
When the pump cover 10 is opened, the fuel passage on the pump cover 10 is formed linearly, so that the air bubbles can be promptly discharged to the fuel tank A. Therefore, the fuel passage 20 leading from the fuel tank A to the fuel pump 8
The accumulation of air bubbles in the fuel passage 20 is eliminated.
Even if the fuel tank 23 is installed above, it is possible to prevent air bubbles from being fed into the fuel chamber 6 of the carburetor, and to prevent air bubbles from causing changes in the flow rate of the supplied fuel and fluctuations in engine rotation during engine operation. could have been prevented.

In this manner, various problems such as fluctuations in engine rotation caused by air bubbles being supplied to the carburetor can be prevented. Furthermore, in a general-purpose engine equipped with a backpack-type fuel tank, the fuel tank is located near the user's hand, making it easier to operate the fuel tank.
Furthermore, since the fuel pot is formed integrally with the pump cover, there are effects such as lower overall cost compared to providing the fuel pot alone.

In the above embodiment, the pulsating pressure acting chamber is formed on the side of the carburetor body and the pump chamber is formed on the pump cover side. Even when a chamber is formed, the effect is the same.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical cross-sectional view showing a conventional example, FIG. 2 is a vertical cross-sectional view showing an embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view showing another embodiment of the present invention. 1... Carburetor body, 8... Fuel pump, 10...
...Pump cover, 23...Fuel tip.

Claims (1)

[Scope of utility model registration request] In a carburetor that forms a fuel pump with a pump cover that is connected to a high-positioned fuel tank through a fuel passage and is attached to a part of the main body with a check valve and a pump membrane in between, the fuel passage is formed on the pump cover. 1. A carburetor, characterized in that a fuel pot that opens and closes is installed, and the fuel passage is configured to be linear when the fuel pot is opened.