JP2537463Y2 - Fuel tank breather device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breather device for a fuel tank mounted on a bush cutter or the like, and more particularly, to a fuel capable of preventing an adverse effect due to fuel leakage from a breather port and improving the performance of an air cleaner. The present invention relates to a breather device for a tank.

[0002]

2. Description of the Related Art A working machine such as a brush cutter is equipped with a two-stroke engine and a fuel tank for storing fuel for operating the two-stroke engine. The fuel in the fuel tank is supplied from the intake system of the two-stroke engine to the combustion chamber of the two-stroke engine. It is supplied to. In a conventional fuel tank, a breather port is provided on an upper wall portion of the fuel tank so as to be exposed to the air space, so that the internal pressure of the fuel tank is maintained at substantially the atmospheric pressure.

[0003]

In the conventional fuel tank, when a work machine such as a brush cutter is greatly inclined or turned upside down, the fuel in the fuel tank leaks to the outside through a breather port, and the fuel is discharged. Contaminating the tank surface and ground,
Also, when flowing down to the two-cycle engine body,
There is also a risk of fire.

[0004] An object of the present invention is to provide a breather device for a fuel tank which can avoid the risk of contamination and fire even if the fuel in the fuel tank leaks from the breather port.

In the breather device for a fuel tank (60) of the present invention, a breather port (66) formed at an upper portion of a breather pipe (68) derived from an upper steam space in the fuel tank (60) is connected to a two-cycle. The filter was opened in the filter element (38) of the air cleaner (28) of the engine intake system or opened in contact with the surface of the filter element (38).

[0006]

[Function] The breather port (66) comes into contact with the filter element (38) of the air cleaner (28) or the filter element (38).
Due to the opening inside, it is maintained almost at atmospheric pressure. When the fuel tank (60) is in a normal posture, the breather port (66) communicates with the upper vapor space in the fuel tank (60). If the pressure difference between the inside and outside of the fuel tank (60) increases due to changes in the vapor pressure inside the fuel tank (60) due to temperature changes, fuel consumption, etc., the atmospheric pressure of the breather port (66) will increase.
(60) to the fuel tank (6)
The inside of 0) is maintained at approximately atmospheric pressure.

[0007] When the fuel tank (60) is greatly inclined and the liquid level swings greatly and undulates, the connection in the fuel tank (60) to the breather port (66) becomes lower than the fuel level, Part of the fuel in the fuel tank (60) flows toward the breather port (66) and leaks from the breather port (66). The leaked fuel penetrates the filter element (38) of the air cleaner (28),
It is absorbed by the filter element (38), and is prevented from flowing down to another part such as the surface of the fuel tank 60 or to be transmitted. The fuel adsorbed by the filter element (38) is guided together with the intake air into the combustion chamber (21) of the engine (10) and burns with the operation of the engine (10). In addition, the filter element (38) increases the stickiness as the fuel permeates, thereby increasing the ability to collect foreign substances passing therethrough.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 is a structural diagram of the two-stroke engine 10 including the carburetor 26 on the intake system side. The two-stroke engine 10 is mounted on a small working machine such as a brush cutter or a backpack power spreader. The two-stroke engine 10 includes a cylinder 12, and a crankcase 14 joined to a lower surface of the cylinder 12,
The crankshaft 16 is rotatably supported on the side wall of the crankcase 14 at both ends. The piston 20 reciprocates vertically in the cylinder 12, and the cylinder
A combustion chamber 21 is defined between the combustion chamber 21 and the inner surface of the combustion chamber. The connecting rod 18 is connected to the piston 20 and the crankshaft 16 at the upper and lower ends, respectively. The intake port 22 is formed on the side of the cylinder 12, and an insulator 24, a carburetor 26, and an air cleaner 28 are connected in series to the intake port 22 side of the cylinder 12 from the intake port 22 side. The gaskets 30, 31, and 32 are interposed at the junction between the cylinder 12 and the insulator 24, at the junction between the insulator 24 and the carburetor 26, and at the junction between the carburetor 26 and the air cleaner 28 to maintain airtightness. .
The air cleaner 28 includes a filter element 38 that is pressed by the base side case 54 and the cover side case 56 from both sides by tightening a screw 58. The filter element 38
It is made of sponge material and has an annular shape. The passage 34 of the insulator 24 and the venturi passage 36 of the carburetor 26 are connected to the intake port 22 of the cylinder 12 so that the center lines thereof coincide with each other.After the outside air passes through the filter element 38 of the air cleaner 28, the venturi passage 36 And the intake port 22 through the passage 34.

The pulse passages 40, 42, 44 are formed in the cylinder 12, the insulator 24, and the carburetor 26, respectively, and are connected through the through holes 46, 48 of the gaskets 30, 31, respectively. The pulse passage 44 of the vaporizer 26 is connected to the pulse passage 42 of the insulator 24 at a connection port 52 on the insulator 24 side. Pulsating pressure is generated in the crankcase 45 in the crankcase 14 with the operation of the two-stroke engine 10,
This pulsating pressure is transmitted to the pulse passage 44 via the pulse passages 40 and 42. The pulse passage 44 communicates with a diaphragm chamber (not shown) of a diaphragm pump (not shown) for supplying the fuel in the fuel tank 60 to the carburetor 26, and is connected to a crank chamber 45 from the pulse passages 40 and 42. The pulsating pressure is transmitted to the diaphragm chamber.

FIG. 1 is a structural view of a fuel tank. The fuel tank 60 is disposed below the two-stroke engine 10 and its intake system, and stores fuel for operating the two-stroke engine 10 therein. The cylindrical insertion hole 62 is
The filter element 38 is formed at the lowermost portion in the radial direction of the filter element 38, opens at the outer peripheral portion of the filter element 38 facing the fuel tank 60, and is located inside the filter element 38 at the upper end. The bulging loading member 64 is fitted into the insertion hole 62 from below, and is fixed to the insertion hole 62,
A breather port 66 is provided at the upper end. Breather line 68
It penetrates the slit at the bottom of the cover side case 56, extends linearly in the vertical direction, and has a loading member at each of the upper and lower ends.
64 and the upper wall of the fuel tank 60. The upper vapor space in the fuel tank 60 communicates with the breather port 66 of the loading member 64 via the breather line 68.

The operation of the embodiment will be described. When the fuel tank 60 is in a normal posture, the breather port 66 communicates with the upper vapor space in the fuel tank 60. In addition, the portion in the filter element 38 where the breather port 66 is located is maintained at substantially atmospheric pressure. Therefore, when the pressure difference between the inside and outside of the fuel tank 60 increases due to a change in the vapor pressure in the fuel tank 60 due to temperature fluctuations and fuel consumption, almost the atmospheric pressure at the breather port 66 passes through the breather line 68. Thus, the fuel is introduced into the upper space in the fuel tank 60, and as a result, the inside of the fuel tank 60 is maintained at substantially the atmospheric pressure.

With the change in the attitude of the working machine, the fuel tank 60
When the liquid level is greatly inclined and the liquid level is greatly rocked and waved, the connection of the breather line 68 to the fuel tank 60 becomes lower than the fuel level in the fuel tank 60, and the fuel in the fuel tank 60 is A portion flows through the breather line 68 toward the breather port 66 and leaks from the breather port 66. The leaked fuel is
Infiltrate the filter element 38, filter element
It is adsorbed by 38 and flows down or travels from the breather port 66 to other parts such as the surface of the fuel tank 60,
It is possible to prevent the surface of 60, the side of the engine, etc. from being polluted and to cause a fire or the like. During operation of the two-stroke engine 10, the fuel adsorbed on the filter element 38
Two-stroke engine 10 via intake passage with intake air
Is introduced into the combustion chamber 21 and burned. Further, the filter element 38 increases the stickiness as the fuel permeates, and enhances the ability to collect foreign matter. Thereby, the filtering function of the filter element 38 for the intake air is increased.

In the embodiment, the breather port 66 is opened in the filter element 38 of the air cleaner 28. However, the breather port 66 is opened only in contact with the outer peripheral surface of the filter element 38 without being inserted into the filter element 38. It may be.

[0014]

According to the invention, the breather port for communicating the inside of the fuel tank with the air space opens in the filter element of the air cleaner of the two-stroke engine intake system or opens in contact with the surface of the filter element. The fuel to be leaked to the air, particularly the oil contained in the fuel, permeates into the filter element of the air cleaner and is adsorbed. Therefore, it is possible to avoid adverse effects such as contamination of the fuel tank surface or the like due to fuel leaking from the breather port and a risk of fire due to adhesion to the engine surface.

According to the invention, the fuel leaked from the breather port, particularly the oil contained in the fuel, penetrates into the filter element, thereby increasing the stickiness and enhancing the ability to collect foreign substances. Function increases.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a fuel tank.

FIG. 2 is a structural diagram of an intake system side of a two-cycle engine including a carburetor.

[Explanation of symbols]

 Reference Signs List 10 two-stroke engine (engine) 21 combustion chamber 28 air cleaner 38 filter element 60 fuel tank 66 breather port

Claims (1)

(57) [Scope of request for utility model registration] 1. A fuel tank (60) having a steam space (60).
A breather port (66) formed at an upper portion of the discharged breather pipe (68) is opened into a filter element (38) of an air cleaner (28) of a two-cycle engine intake system.
Or, open the filter element (38) in contact with the surface.
Breather device for a fuel tank, characterized in that allowed.