JPH051842U - Diaphragm vaporizer - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the overflow fuel discharged from the diaphragm chamber to the fuel tank when the starting pump of the diaphragm type carburetor is operated. A fuel storage chamber for storing the fuel discharged from the overflow passage is provided, and the storage chamber is connected to the fuel tank via a check valve that allows a flow in the fuel tank direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a diaphragm type carburetor used in engines such as brush cutters and chain saws.

[0002]

[Prior Art]

 In the diaphragm type carburetor, the fuel in the diaphragm chamber evaporates due to the heat of the engine after the engine is stopped, so it is necessary to fill the diaphragm chamber with fuel when the engine is started next time. Therefore, conventionally, before starting the engine, the fuel is supplied by the starting pump to discharge the air in the diaphragm chamber and supply the fuel into the chamber. The fuel discharged from the overflow passage confirms that the diaphragm chamber is filled with fuel.

[0003]

[Problems of conventional technology]

 However, due to environmental issues being highlighted in recent years, it has become necessary to prevent fuel from being released into the atmosphere even in the above-mentioned small engines. Therefore, in the diaphragm type carburetor described above, it may be possible to connect the overflow hole to the fuel tank in order to return the overflow fuel to the fuel tank. In this case, the high pressure in the fuel tank causes the fuel to overflow when the overflow valve is opened. The fuel in the tank flows back into the diaphragm chamber, overflows from the nozzle to the intake passage, and the startability deteriorates.

An object of the present invention is to provide a diaphragm type carburetor capable of returning overflow fuel to a fuel tank and having a good startability without backflow of fuel from the fuel tank to the intake passage.

[0005]

[Technical means for solving problems]

 According to the present invention, a fuel storage chamber for storing the fuel discharged from the overflow passage is provided, and the storage chamber is connected to the fuel tank via a check valve that allows a flow in the fuel tank direction. Characterize.

[0006]

[Action]

 When the overflow valve is opened by the ticker operation and the starting pump is operated, fuel is fed from the fuel tank to the diaphragm chamber, and the air in the chamber is discharged to the fuel storage chamber through the overflow passage. After the diaphragm chamber is filled with fuel, the excess amount of fuel is discharged to the fuel storage chamber through the overflow passage and stored in the chamber. After the engine is started, the pressure in the fuel tank becomes negative, so that the fuel in the fuel storage chamber is sucked into the fuel tank through the check valve.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a diaphragm type carburetor, which is provided with an intake passage 3 penetrating the body 2. The upstream side of the intake passage 3 is connected to an air cleaner (not shown), and the downstream side is connected to an intake port of an engine (not shown). Has been done. A throttle valve 4 for varying the effective diameter of the intake passage 3 is arranged in the intake passage 3. A fuel nozzle 5 is opened in the suction passage wall below the throttle valve 4, and the other end of the fuel nozzle 5 is connected to a diaphragm chamber 6.

Reference numeral 10 denotes a fuel pump driven by the operating pressure of the engine. The fuel pump 10 is a conventionally well-known diaphragm pump including a pump diaphragm 11 and a pair of check valves 12 and 13. By applying the operating pressure of the engine to the pressure chamber 14 formed on one side of the pump diaphragm 11, for example, the pressure in the crank chamber in a two-cycle engine, the pump diaphragm 11 is vibrated and the fuel is discharged from the fuel tank 15. The gas is sucked into the pump chamber 17 formed on the other side of the pump diaphragm 11 through one check valve 12, and is pumped from the other check valve 13 into the diaphragm chamber 6 through the fuel passage 18.

At the inlet of the diaphragm chamber 6 of the fuel passage 18, it operates so as to connect / disconnect the passage 18 in relation to the metering diaphragm 19, that is, to connect / disconnect the communication between the fuel pump 10 and the diaphragm chamber 6. A fuel valve 20 is provided. A lever 22 is arranged between the fuel valve 20 and the metering diaphragm 19 so that one side is connected to the fuel valve 20 and the other side is connected to the metering diaphragm 19 with the spindle 21 as the center. ing. Therefore, when a strong negative suction pressure acts on the diaphragm chamber 6 through the fuel nozzle 5, the metering diaphragm 19 causes the fuel valve 2 to pass the fuel into the diaphragm chamber 6 via the lever 22 so as to introduce the fuel into the diaphragm chamber 6. 0 is held at the open position of the fuel passage 18. When the strong negative pressure in the diaphragm chamber 6 disappears due to the introduction of the fuel into the diaphragm chamber 6, the fuel valve 20 is moved into the diaphragm chamber 5 by the biasing force of the compression spring 23 engaging with the lever 22. The passage 18 is closed to prevent the introduction of fuel.

Reference numeral 24 is a ticker for pushing up the diaphragm and opening the fuel valve 20. Reference numeral 25 denotes a starter pump, and by repeatedly operating this pump, the fuel in the fuel tank 15 is sucked and fed to the diaphragm chamber 6 through the fuel pump 10. An overflow passage 26 is connected to the diaphragm chamber 6. An overflow valve 27 that closes the passage 26 and opens in conjunction with the ticker 24 is arranged in the overflow passage 26. On the other hand, the other end of the overflow passage 26 is connected to a fuel storage chamber 28, and the fuel discharged from the overflow passage 26 is stored in the chamber 28. The fuel storage chamber 28 is connected to the fuel tank 15 via a check valve 30 provided at the bottom. The check valve 30 is normally closed and is opened by the negative pressure in the fuel tank 15 generated during the operation of the engine, so that the fuel in the storage chamber 28 is sucked into the tank 15. ing. A window 31 is provided on the side surface of the fuel storage chamber 28 to confirm that the fuel has been discharged into the chamber 28. Reference numeral 32 is an atmosphere passage for guiding the atmosphere into the fuel storage chamber 28, and its atmospheric opening is provided so that the fuel in the fuel storage chamber 28 does not flow out even when the machine is tilted.

Next, the operation of the above embodiment will be described. When the fuel valve 20 and the overflow valve 27 are opened by pushing the ticker 24 and the starter pump 25 is operated at the same time, the fuel is fed from the fuel tank 15 to the diaphragm chamber 6, and at the same time, the air in the chamber 6 is passed through the overflow passage 26 to keep the fuel. It is pushed into the reservoir 28 and released into the atmosphere. After the diaphragm chamber 6 is filled with fuel, an excess amount of fuel is discharged to the fuel storage chamber 28 through the overflow passage 26. Check the discharge and check the above-mentioned ticker 24 and the starting pump. The operation of 25 is completed. After the engine is started, the pressure inside the fuel tank 15 gradually becomes negative, so that the check valve 30 opens and the fuel in the storage chamber 28 is sucked into the fuel tank 15.

[0012]

[Effect of the device]

 As described in detail above, according to the present invention, the fuel discharged from the diaphragm chamber of the carburetor to the overflow passage when the starting pump is operated is stored in the fuel storage chamber, and this fuel is generated during the operation of the engine. Since the negative pressure inside the tank is used to draw it into the tank, it is possible to prevent the fuel from being released into the atmosphere, which is effective for environmental protection. In addition, since the fuel in the fuel tank does not flow back into the intake passage of the carburetor during this tickle operation, the engine startability does not deteriorate.

[Brief description of drawings]

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

[Explanation of symbols]

 2 Body 6 Diaphragm chamber 24 Ticla 25 Starting pump 26 Overflow passage 27 Overflow valve 28 Fuel storage chamber 30 Check valve

Claims (1)

[Claims for utility model registration] [Claim 1] A diaphragm chamber in which fuel fed under pressure from a fuel pump is adjusted to a constant pressure and ejected from a nozzle,
In a diaphragm type carburetor equipped with a Ticla that pushes up a diaphragm and opens a fuel valve, and an overflow valve that is interlocked with this Ticla and that opens the fuel valve at the same time that opens the overflow passage of the diaphragm chamber,
Connecting the other end of the overflow passage to the fuel storage chamber,
A diaphragm type carburetor characterized in that the storage chamber and the fuel tank are connected via a check valve which allows a flow in the direction of the fuel tank.