JPH0346210Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an auxiliary fuel supply device for improving the startability of a small engine equipped with a diaphragm carburetor.

<Prior Art> In general, a small engine equipped with a diaphragm type carburetor requires that the fuel chamber of the carburetor be filled with fuel before starting the engine. Therefore, conventionally, as disclosed in Japanese Utility Model Publication No. 51-43315, a manual pump was used to feed the fuel in the fuel tank to the fuel chamber, and a diaphragm of the fuel chamber was pushed up to forcefully close the fuel valve at the inlet of the fuel chamber. The engine is equipped with a takera lever that opens the overflow valve at the same time as the overflow valve is opened, and the manual pump and takera lever are operated simultaneously before starting the engine to introduce fuel into the fuel chamber and to fill the fuel chamber with fuel from the fuel overflow. A mechanism is adopted to detect this.

In addition, in order to make it easier to start the engine, it is desirable to supply a rich mixture at the time of starting, but even if the fuel chamber is filled with fuel, the amount of fuel supplied from the nozzle will match the operating conditions after starting. Therefore, in order to supply the desired rich air-fuel mixture to the engine, it is necessary to further limit the amount of intake air by operating the choke valve.

<Problems with the Prior Art> As described above, when starting up the above device, it is necessary to operate both the manual pump and the takera lever, which requires both hands and is cumbersome to handle. Furthermore, after filling the fuel chamber with fuel, it is necessary to perform a choke operation to obtain a rich mixture for starting, and these operations are extremely troublesome.

<Objective> An object of the present invention is to provide an auxiliary fuel supply device that eliminates the above-mentioned troublesome work at the time of starting and supplies a rich air-fuel mixture for engine starting without using a choke mechanism.

<Structure of the invention> The invention provides an auxiliary fuel storage chamber integrated with or separate from the carburetor, in which an air-fuel mixture passage connecting to the intake passage downstream of the throttle valve is opened in the upper part, and a mixture passage is opened in the lower part of the storage chamber to connect to the intake passage downstream of the throttle valve. An air passage is opened and a transparent window is provided on the side wall, and the fuel storage chamber is connected to a fuel supply passage between the fuel tank and the fuel valve of the carburetor by a passage, and a passage is connected from the manual pump to the fuel storage chamber. A check valve is provided that allows only the flow of fuel toward the auxiliary fuel storage chamber and opens at a fuel pressure lower than the opening pressure of the fuel valve, and a manual pump is further disposed on the fuel supply path upstream from the connection part of the passage. It was established.

<Operation> When the manual pump is operated when starting the engine, the fuel in the fuel tank is pumped to the carburetor, but since the fuel valve at the diaphragm chamber inlet is closed, the fuel pressure in the passage increases and this When the fuel pressure in the passage exceeds a specified value, the check valve opens, and fuel flows into the auxiliary fuel holding chamber and is held there.

Also, by visually checking the amount of fuel reserved through the transparent window, the amount can be adjusted according to the outside temperature and engine temperature.

Then, when the recoil starter is pulled to start the engine, the engine's intake negative pressure acts on the auxiliary fuel holding chamber through the mixture passage, and the fuel in the holding chamber is bubbled by the air flowing in from the air passage. The fuel becomes foamy and is sucked out into the intake passage, and together with the air flowing through it, it creates a rich mixture for starting, which is then sucked into the engine.

During warm-up operation following engine startup, the fuel in the auxiliary fuel storage chamber is foamed by the air sequentially introduced from the air passage, and is drawn into the air intake passage as foamy fuel. As this warm-up operation progresses, the amount of fuel in the holding chamber decreases, and accordingly, the amount of fuel supplied from the mixture passage decreases. As a result, the concentration of the air-fuel mixture supplied to the engine gradually decreases as the warm-up operation progresses, thereby allowing the warm-up operation to be performed smoothly.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.
FIG. 1 shows an embodiment in which an auxiliary fuel storage chamber according to the present invention is provided on a cover of a fuel pump, and FIG. 2 shows an embodiment in which this auxiliary fuel storage chamber is provided inside an air cleaner.

1 is a diaphragm type vaporizer. An intake passage 3 is provided through the carburetor main body 2 of the diaphragm type carburetor 1, and a throttle valve 4 faces the intake passage 3 from above so as to be movable forward and backward. A main nozzle 5 is opened in the bottom wall of the intake passage 2 below the throttle valve 4, and a jet needle 6 that hangs down from the throttle valve 4 is inserted into the main nozzle 5. The main nozzle 5 communicates with a diaphragm chamber 8 via a fuel orifice 7.

Further, this diaphragm type carburetor is equipped with a fuel pump 10 driven by engine pulsation. This fuel pump 10 has fuel supply passages 11 and 1.
2 are connected to each other, one fuel supply passage 11 is connected to the fuel tank 13 through a connection port 14 to the fuel tank 13, and the other fuel supply passage 12 is connected to the diaphragm chamber 8.

The diaphragm chamber 8 has a bottom wall formed by a diaphragm 15 , and an inlet of the diaphragm chamber 8 of the fuel supply passage 12 is connected to the diaphragm 15 to connect and disconnect the fuel supply passage 12 , that is, the fuel pump 10 is connected to the diaphragm chamber 8 . A fuel valve 16 is provided that operates to disconnect and disconnect communication between the diaphragm chamber 8.
Between the fuel valve 16 and the diaphragm 15,
A lever 18 having a support shaft 17 is disposed, and one side of the lever 18 is connected to the fuel valve 16 around the support shaft 17.
The other side is connected to the diaphragm 15. Therefore, when a strong suction negative pressure acts on the diaphragm chamber 8 through the main nozzle 5, the diaphragm 15 moves upward and the lever is pressed to introduce fuel from the fuel pump 10 into the diaphragm chamber 8 through the fuel supply path 12. 18 to hold the fuel valve 16 in the open position. In addition, the diaphragm chamber 8
When the strong negative pressure in the chamber 8 disappears by introducing fuel into the diaphragm chamber 8, the fuel valve 16 closes the diaphragm chamber 8 by the biasing force of the compression spring 19 that engages the lever 18.
In order to prevent the introduction of fuel into the fuel supply path 1
Block 2.

Further, the carburetor 1 is provided with an auxiliary fuel supply device 20 according to the present invention. The auxiliary fuel supply device 20 will be described in detail below. Reference numeral 21 is an auxiliary fuel storage chamber provided integrally with or separately from the carburetor 1. The auxiliary fuel storage chamber 21 is connected to the fuel tank 13 through a passage 22, and connected in the middle of the fuel supply path 11 or 12 connecting the fuel valve 16 of the device,
A manual pump 23 is disposed in the fuel supply path upstream of the connection portion of the passage 22. A mixture passage 24 connecting to the intake passage 3 downstream of the throttle valve 4 is opened at the top of the auxiliary fuel storage chamber 21, and an air passage 25 is opened at the bottom.
A check valve 26 is disposed in the middle of the valve 4 to prevent backflow of fuel due to pulsation of the intake negative pressure. A check valve 27 is disposed in the middle of the passage 22, which allows only the flow of fuel from the manual pump 23 toward the auxiliary fuel storage chamber 21, and which opens at a fuel pressure lower than the opening pressure of the fuel valve 16. . Further, the side surface of the auxiliary fuel holding chamber 21 is provided with the holding chamber 2 from the outside of the carburetor.
A transparent window 28 is provided for viewing the fuel storage chamber within the fuel storage chamber 1. 29 is an air cleaner, 30 is a cleaner cover, and 31 is a fuel pump cover.

The operation of the embodiment configured as above will be explained.

When starting the engine, if the manual pump 23 is operated, the fuel in the fuel tank 13 is pumped to the carburetor 1, but the fuel valve 16 at the inlet of the diaphragm chamber 8
is closed, the fuel pressure in this passage 22 increases, and when the fuel pressure in this passage 22 exceeds the specified value, the check valve 27 opens, and the auxiliary fuel storage chamber 2
Fuel flows into 1 and is held. At this time, by visually checking the amount of fuel reserved through the transparent window 28,
The amount can be adjusted in response to outside air temperature and engine temperature.

Then, when the recoil starter is pulled to start the engine, the engine's intake negative pressure acts on the auxiliary fuel retention chamber 21 through the mixture passage 24, and the fuel in the retention chamber 21 flows into the auxiliary fuel retention chamber 21 through the air passage 25. The air is bubbled to form foamy fuel, which is sucked out into the intake passage 3, and together with the air flowing there, a rich air-fuel mixture for starting is generated, which is then sucked into the engine.

During warm-up operation following engine startup, the fuel in the auxiliary fuel storage chamber 21 is sequentially transferred to the air passage 25.
The fuel is foamed by the air flowing in from the fuel, and is sucked into the air intake passage 3 as foamy fuel. As this warm-up operation progresses, the amount of fuel in the holding chamber 21 decreases, and accordingly, the amount of fuel supplied from the mixture passage 24 decreases. As a result, the concentration of the air-fuel mixture supplied to the engine gradually decreases as the warm-up operation progresses, thereby allowing the warm-up operation to be performed smoothly.

When the fuel in the auxiliary fuel storage chamber 21 is completely consumed, the air passage 2 is discharged from the mixture passage 24.
Only the air that has flowed in from 5 is blown out, and this air is constantly supplied to the engine as low-speed air.

In the example shown in FIG. 3, the auxiliary fuel storage chamber 21
A scale 31 is marked on the transparent window 29 or the side of the transparent window 29 to display the amount of fuel reserved according to the outside temperature and engine condition.By displaying the amount of auxiliary fuel in this way, it is possible to A concentrated air-fuel mixture can be generated, and the engine can be started reliably.

In the example shown in FIG. 4, the auxiliary fuel storage chamber 21
An air nozzle 32 is installed in the air passage 25 that opens at the bottom of the
is provided in an upright position, and when the oil level in the holding chamber 21 drops below the upper end opening of the air nozzle 32, a large amount of air is introduced from the air nozzle 32 to generate an even leaner mixture for starting. can.
Further, a small hole 33 is formed on the lower side of the air nozzle 32.
is provided, and when the amount of fuel in the holding chamber 21 falls below the upper end of the air nozzle 32, air is allowed to flow into the fuel through the small hole 33 to foam the fuel and turn it into foamy fuel. There is.

<Effects> As detailed above, according to the present invention, an appropriate amount of auxiliary fuel can be reserved by operating the manual pump prior to starting the engine, and this auxiliary fuel can be used to start the engine and subsequently. It can be supplied to the engine during warm-up operation. Therefore, it is possible to omit the taker mechanism and the choke mechanism that were required in the conventional diaphragm type carburetor, making it easier to start the engine, and greatly eliminating the trouble of starting this type of carburetor. can.

Furthermore, in the above embodiment, an example was explained in which the present invention was applied to a diaphragm type carburetor equipped with a sliding throttle valve, but the present invention could also be applied to a carburetor equipped with a butterfly type or rotary type throttle valve. The same effect can be obtained.

[Brief explanation of drawings]

1 and 2 are longitudinal cross-sectional views showing an embodiment of a vaporizer according to the present invention, FIG. 3 is a side view showing the main parts of another embodiment of the present invention, and FIG. FIG. 2... Carburetor body, 3... Intake passage, 21... Auxiliary fuel holding chamber, 22... Passage, 23... Manual pump, 24... Mixture passage, 25... Air passage, 2
7...Check valve, 28...Transparent window.

Claims (1)

[Claims for Utility Model Registration] (1) A device provided in a carburetor to improve the startability of the engine, which has an air-fuel mixture passage connected to the intake passage downstream of the throttle valve at the top and a gas mixture passage at the bottom. An auxiliary fuel storage chamber with an open air passage and a transparent window on the side, a passage connecting the storage chamber to a fuel supply passage between the fuel tank and the fuel valve of the carburetor, and an auxiliary fuel storage chamber provided on the passage. A check valve that allows only the flow of fuel toward the fuel chamber and opens at a fuel pressure lower than the opening pressure of the fuel valve, and a manual pump disposed on the fuel supply path upstream of the connection part of the passage. Includes carburetor auxiliary fuel supply device. (2) The carburetor according to claim 1 of the utility model registration claim, characterized in that a scale indicating an amount of auxiliary fuel according to outside temperature and engine temperature is displayed on the transparent window or on the side of the transparent window. auxiliary fuel supply system. (3) The auxiliary fuel supply device for a carburetor as set forth in claim 1, wherein an air pipe of a specified height is provided upright in the air passageway opening at the bottom of the auxiliary fuel storage chamber.