JPH0683952U - Circulating vaporizer - Google Patents

Abstract

(57) [Summary] [Purpose] To suppress the rise of the oil level in the fuel chamber when the circulating carburetor is tilted. [Structure] A fuel tank 7 is arranged below the circulation type carburetor 6, and fuel is supplied to a fuel chamber 17 of the carburetor by a fuel pump 21 while the engine is in operation. In the circulation type carburetor in which the fuel overflows to form a constant oil level and the overflowed fuel is returned to the fuel tank, a breather passage of the fuel tank
34 is connected to the air vent 20 of the carburetor, and a tank side opening 35 of the breather passage is provided from the center of the fuel tank to the carburetor side.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circulation type vaporizer used for small engines such as brush cutters, cultivators and power sprayers.

[0002]

[Prior art]

 A fuel tank is located below the circulating carburetor.The fuel pump supplies fuel to the fuel chamber of the carburetor while the engine is operating, and when the oil level in the fuel chamber rises above a certain level, the fuel overflows and becomes constant. In a small engine that forms an oil level and allows this overflowed fuel to be returned to the fuel tank, when the engine leans toward the carburetor side, the fuel in the fuel tank is vaporized from the return passage as shown in Fig. 4. Since it flows backward into the fuel chamber of the vessel, the oil level in the fuel chamber rises above the specified level, and there is a drawback that fuel is excessively supplied and engine stall occurs.

[0003]

[Problems of conventional technology]

 When the small engine equipped with the circulation type carburetor is tilted toward the carburetor side, the present invention suppresses the rise of the oil level in the carburetor fuel chamber by the negative pressure in the fuel tank, and also uses the fuel pump. The purpose is to reduce the amount of fuel supply and prevent excessive fuel supply to the engine.

[0004]

[Technical means for solving problems]

 The present invention is characterized in that the breather passage of the fuel tank is connected to the air vent of the carburetor, and the tank side opening of the breather passage is provided from the center of the fuel tank to the carburetor side.

[0005]

[Action]

 According to the above configuration, when the engine leans toward the carburetor side, the fuel in the fuel tank flows back through the return passage, but at the same time, the opening of the breather passage on the fuel tank side is below the fuel, The tank is closed and the pressure in the tank drops due to the suction operation of the fuel pump. As a result, while the atmospheric pressure is acting in the fuel chamber of the carburetor, the pressure in the fuel tank is lower than that, and the oil level in the fuel chamber of the carburetor is lower than that in the fuel tank. Further, since the amount of fuel to be fed to the fuel chamber of the carburetor by the fuel pump is reduced, the rise of the oil level in the fuel chamber is suppressed, and engine stall during this tilted state can be prevented.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes an engine body, which is composed of a cylinder block 2 and a crankcase 3. An intake port (not shown) is provided on the side wall of the cylinder block 2, and the circulation type carburetor 6 is attached to the intake port. Reference numeral 4 is an insulator interposed between the cylinder block 2 and the circulation type vaporizer 6. A fuel tank 7 is attached to the lower part of the crankcase 3.

An intake passage 12 is provided in the body 11 of the circulation type carburetor 6, the upstream side of the intake passage 12 is connected to an air cleaner (not shown), and the downstream side is connected to the intake port. A throttle valve 13 is provided in the intake passage 12 so as to be movable back and forth in a substantially orthogonal direction, and the effective diameter of the intake passage 12 is controlled. A main nozzle 14 is provided on the bottom wall of the intake passage 12 below the throttle valve 13, and a jet needle 15 depending from the throttle valve 13 is inserted into the main nozzle 14. The lower end of the main nozzle 14 communicates with the bottom of the oil in the fuel chamber 17 via the main jet 16. A return passage 18 is provided at a side portion of the fuel chamber 17, and a weir 8 having a prescribed oil surface height is provided between the return passage 18 and the other end of the return passage 18 is connected to the fuel tank 7 through a pipe 19. Has been done. A wire 9 is arranged between the fuel chamber 17 and the return passage 18, and a small amount of fuel is constantly discharged from the fuel chamber to the return passage by the wire 9 so that the fuel chamber is automatically kept in a closed state after the engine is stopped. It is supposed to be empty. An air vent passage 20 is opened in the upper portion of the fuel chamber 17, and the passage 20 is connected to the atmospheric pressure.

The circulation type carburetor 6 includes a fuel pump 21 driven by the operating pressure of the engine. The fuel pump 21 is a conventionally well-known diaphragm pump including a pump diaphragm 22 and a pair of check valves 23 and 24, and applies an operating pressure of the engine to a pressure chamber 25 formed on one side of the pump diaphragm 22. By virtue of this, the pump diaphragm 22 is vibrated, and fuel is sucked from the fuel tank 7 through the check valve 23 on one side into the pump chamber 26 formed on the other side of the pump diaphragm 22, and the other check valve 24 on the other side. Is sent to the fuel chamber 17 via the fuel passage 27. Therefore, when the fuel pump 21 is driven along with the operation of the engine, the fuel is sucked from the fuel tank 7 and supplied to the fuel chamber 17. When the oil level in the fuel chamber 17 reaches the height of the weir 8, the fuel in the fuel chamber 17 overflows into the return passage 18 to form a constant oil level.

A priming pump 31 that can be manually pressed is provided on the outer surface of the carburetor 6, and a pump chamber 32 of the pump is connected to a pump chamber 26 of the fuel pump 21. Therefore, when the priming pump 31 is repeatedly pressed, the fuel in the fuel tank 7 is supplied to the fuel chamber 17 in cooperation with the check valves 23 and 24 of the fuel pump 21.

A breather passage 34 has an opening 35 on the carburetor side from the center of the fuel tank 7, and the other end of the passage 34 is connected to an air vent passage 20 of the carburetor so that the internal pressure of the fuel tank 7 becomes atmospheric pressure. In addition, the fuel is prevented from flowing out of the breather passage 34 when the engine is tilted.

The operation of the above embodiment will be described below. When the engine leans to the carburetor 6 side, the fuel in the fuel tank 7 flows back through the return passage 18, but at the same time, the opening 35 on the fuel tank 7 side of the breather passage 34 becomes under the fuel at the time of leaning. The tank 7 is closed, and the pressure in the tank 7 is reduced by the suction action of the fuel pump 21. As a result, the atmospheric pressure acts on the inside of the fuel chamber 17 of the carburetor due to the air vent passage 20, while the pressure inside the fuel tank 7 becomes lower than that, so that as shown in FIG. Since the oil level Hc in the fuel chamber 17 of the carburetor is lower than the oil level Ht of the carburetor, and the fuel supply amount to the fuel chamber 17 of the carburetor by the fuel pump 21 is reduced, the oil level in the fuel chamber 17 is reduced. The rise of the surface is suppressed, and it is possible to prevent engine stall during this inclined state.

[0012]

[Effect of device]

 As described in detail above, according to the present invention, the engine is constructed by connecting the breather passage of the fuel tank to the air vent of the carburetor and providing the tank side opening of the breather passage from the center of the fuel tank to the carburetor side. When the carburetor side is tilted, the breather passage described above is blocked by fuel.In this case, the suction operation of the fuel pump reduces the pressure in the fuel tank to the pressure in the fuel chamber of the carburetor. As a result, it is possible to prevent the oil level in the fuel chamber from lowering with respect to the oil level in the tank, and to prevent the fuel supply amount of the fuel pump itself from decreasing and the fuel supply to the engine becoming excessive. It is possible to prevent engine stall during this inclination.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory view showing an oil level when the present invention is inclined.

FIG. 4 is an explanatory diagram showing a conventional oil surface when tilted.

[Explanation of symbols]

 1 Engine Body 6 Circulating Vaporizer 7 Fuel Tank 17 Fuel Chamber 18 Return Passage 20 Air Vent Passage 21 Fuel Pump 34 Breather Passage

Claims (1)

[Scope of utility model registration request] 1. A fuel tank is disposed below the circulation type carburetor, and while the engine is operating, fuel is supplied to the fuel chamber of the carburetor by the fuel pump, and when the oil level in the fuel chamber rises above a certain level. The fuel overflows to form a constant oil level,
In the circulation type vaporizer in which the overflowed fuel is returned to the fuel tank, the breather passage of the fuel tank is connected to the air vent of the vaporizer,
A circulation type carburetor, characterized in that the tank side opening of the breather passage is provided from the center of the fuel tank to the carburetor side.