JPS6214356Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is an auxiliary fuel supply mechanism suitable for being incorporated into an internal combustion engine installed as a drive source in a portable working machine such as a chain saw or a brush cutter in order to facilitate the starting of the engine. Regarding.

The carburetor of an internal combustion engine has a built-in fuel supply mechanism for supplying an appropriate amount of fuel to the engine depending on the operating conditions of the engine. There is a problem with the startability of the engine in etc.

For this reason, conventionally, an auxiliary fuel storage means such as a recess is provided in the intake path leading to the intake port of the internal combustion engine via the carburetor, and a fuel supply device such as a hand pump is repeatedly operated prior to starting the engine. It has been proposed to operate to supply auxiliary fuel to the retention means, and to increase the air-fuel mixture at the time of starting the engine by using the auxiliary fuel reserved in the retention means, thereby improving the startability of the engine. was.

However, in the conventional auxiliary fuel supply mechanism, it is difficult to constantly supply a predetermined amount of fuel to the retention means by repeatedly operating the pump, and therefore the amount of auxiliary fuel supplied to the retention means is limited. There were times when there was an excess or deficiency. Insufficient auxiliary fuel supply makes it difficult to easily start the engine because sufficient auxiliary fuel is not retained in the retention means. Further, an excessive amount of auxiliary fuel supplied causes the engine to be temporarily unable to start because the excess amount flows out from the retention means to the intake passage.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an auxiliary fuel supply mechanism that provides stable and good starting performance to an internal combustion engine through easy operation.

The present invention comprises a fuel storage means provided with an intake passage leading to an air supply port of an internal combustion engine via a carburetor, and a metering chamber for storing a predetermined amount of fuel to be supplied to the storage means, and a fuel supply chamber. a metering chamber including a discharge pipe for discharging excess fuel supplied from the device to the outside; a guide path for guiding the fuel in the metering chamber to the storage means; A valve device that is opened to cause a predetermined amount of fuel stored in a metering chamber to flow out to the holding means via the guide path, and when the valve device is opened, fuel flows out from the metering chamber to the holding means. The leak passageway extends from the downstream side of the valve device in the guideway and opens to the atmosphere above the guideway.

According to the present invention, a predetermined amount of fuel can be stored in the metering chamber by operating the fuel feeding device, and a predetermined amount of fuel can be stored in the metering chamber by opening the valve device prior to starting the engine. A fixed amount of fuel can be allowed to flow out into the retention means, thereby allowing the retention means to retain an appropriate predetermined amount of fuel.

The features of the invention will become clearer from the following description of the illustrated embodiment.

FIG. 1 shows, as an example of the present invention, that in the operating state of an internal combustion engine after starting, the operating state can be adjusted by supplying an appropriate amount of fuel to the engine according to the operating state, regardless of the engine's position. An example is shown in which the present invention is applied to a diaphragm type carburetor that is capable of good control of the temperature, and the carburetor is shown in its starting position.

The carburetor 10 includes a carburetor body 14 in which an air hole 12 is formed, and a throttle valve 1 housed in the carburetor body 14 to make the effective diameter of the air hole 12 variable.
6, the throttle valve being shown as a rotary throttle valve. One end of the air hole 12 is
Although not shown, it communicates with an air intake port of an internal combustion engine, for example, a two-stroke engine, via an intake pipe. Also,
The other end of the air hole 12 communicates with an air cleaner via an air pipe (not shown). The air pipe, air hole and intake pipe constitute an intake path for the engine.

The carburetor 10 is provided with a conventionally well-known fuel supply mechanism 24 that includes a fuel pump 18 and a diaphragm chamber 22 whose peripheral wall is partially formed by a diaphragm 20 .

Fuel pump 18 is a diaphragm pump having a diaphragm 26 and a pair of check valves 28,30. A pulsating operating pressure of the engine, for example, crank chamber pressure in a two-stroke engine, is introduced into a diaphragm chamber 32 formed on one side of the diaphragm 26 through an opening 34 . Therefore, when the engine is in operation, the fuel pump 18 pumps fuel in the fuel tank 36 through the opening 38 and one check valve 28 formed on the other side of the diaphragm 26, as is well known in the art. The fuel is absorbed into the pump chamber 40 and is pumped from the other check valve 30 through the passage 42 to the diaphragm chamber 22.

A valve member 44 is provided within the diaphragm chamber 22 to connect and disconnect the passage 42 . The valve member 44 has a swinging lever 48 that engages the diaphragm 20 and receives the spring force of the compression spring 46.
via the diaphragm 20.

The fuel in the diaphragm chamber 22 is pumped by the intake negative pressure generated by the operation of the engine through a fuel supply passage 50 and a conventionally well-known fuel nozzle (not shown) provided in association with the throttle valve 16. ) is sucked into the air hole 12. The fuel sucked from the nozzle is supplied to the engine through the intake passage 12 as a mixture together with the intake air passing through the air cleaner. Also, diaphragm 2
0 opens and closes the valve member 44 in response to the negative pressure acting within the diaphragm chamber 22, whereby fuel is intermittently introduced into the diaphragm chamber 22 through the passage 42.

Therefore, in the operating state of the engine, an appropriate amount of fuel is always stored in the diaphragm chamber 22, and this fuel is supplied to the throttle valve 16 according to the operation amount of the throttle valve 16 accompanying the operation of the throttle lever 16a. Supplied to institutions.

The fuel supply path 50 is provided with a check valve 52 for blocking airflow toward the diaphragm chamber 22 during primer operation, which will be described later, and a needle 54 for adjusting fuel.

The operation of the engine after starting is as described above.
Although the engine is preferably maintained and controlled by the fuel from the fuel supply mechanism 24, when the engine is started, the fuel from the fuel supply mechanism 24 alone does not provide a rich mixture sufficient to improve the startability of the engine. cannot be supplied to said institution.

In order to improve engine starting, an auxiliary fuel supply mechanism 56 according to the present invention is provided in the carburetor 10. This auxiliary fuel supply mechanism 56 includes the air hole 1
2, an auxiliary fuel storage means 58 provided on the upstream side of the throttle valve 16, that is, on the air cleaner side; a quantitative chamber 60 for temporarily storing a predetermined amount of fuel to be supplied to the storage means; and an auxiliary fuel delivery device 62 for delivering fuel to the chamber.

In the illustrated example, the retaining means 58 is the air hole 1
The retaining means 58 is composed of a recess 58a provided in the peripheral wall of No. 2, and a water-absorbing member 58b such as a sponge held in the recess. Further, the retention means 58 can be provided downstream of the throttle valve 16, but in order to prevent fuel trapping caused by the retention means, it is preferable to provide the retention means 58 on the upstream side as described above.

As shown in the figure, the metering chamber 60 is provided in relation to the carburetor main body 14 so as to be located above the holding means 58 in the attitude of the carburetor 10 when the engine is started. A discharge pipe 64 that communicates with the metering chamber 60 and extends outward of the vaporizer body 14 is provided in the upper portion of the side wall defining the metering chamber 60 . An opening 66 of the metering chamber 60 is provided in the lower part of the side wall, and a valve device 68 for opening and closing the opening is provided in connection with the opening 66 .

The valve device 68 includes a guide portion 70 aligned with the opening 66 and extending laterally to the side opposite the metering chamber 60.
A valve member 72 is slidably disposed in the valve member 72 and a coil spring 74 is provided to apply a spring force to the valve member toward a closed position of the opening 66. One end of the valve member 72 extends into the metering chamber 60 through the opening 66;
A valve portion 72a is formed at the end portion and is engageable with an annular sealing member 76 disposed at the edge of the opening 66. The spring 74 is connected to the metering chamber 60
The valve portion 72a is pressed against the sealing member 76 forming a valve seat. The other end 72b of the valve member 72 projects to the outside of the carburetor. Therefore, by pushing the protruding end 72b of the valve member 72, the opening 66 can be opened. The valve member 72 includes an annular seal member 7 for maintaining airtightness with the guide portion 70.
8 is provided, and a reduced diameter portion 72c is further formed between the seal member and the valve portion 72a.

The carburetor main body 14 has one end connected to the guide portion 7.
A guide path 80 that opens to the guide portion 70 is formed at a lower portion of the circumferential wall of 0 that corresponds to the reduced diameter portion 72c. Communication between the open end of the guide path 80 and the guide portion 70 is not interrupted by the sliding movement of the valve member 72 . The other end of the guide path 80 opens to the wall surface of the air hole 12 above the retaining means 58. Further, one end of a leak passage 82 is open in an upper portion of the peripheral wall of the guide portion 70 corresponding to the reduced diameter portion 72c. The other end of the leak passage 82 is open to the atmosphere above the guide passage 80. The open end of the leak passage 82 to the guide portion 70 is not closed by the sliding movement of the valve member 72. Therefore, the leak passage 82 provided above the guide passage 80 is always connected to the guide part 70.
It is in communication with the guide path 80 via.

In the illustrated example, the fuel feeding device 62 that feeds fuel to the metering chamber 60 is a hand pump that includes a cap-shaped elastic body 86 that defines a pump chamber 84 and a pair of check valves 88 and 90. be. A suction port 92 of the pump chamber 84 provided with one check valve 88 communicates with the diaphragm chamber 22 through a suction passage 94 . A discharge port 96 of the pump chamber 84 in which the other check valve 90 is provided communicates with the metering chamber 60 through a discharge passage 98 that opens into the metering chamber 60 at its lower portion.

The auxiliary fuel supply mechanism pump 62 is manually operated prior to starting the engine. When the elastic body 86 of the pump 62 is repeatedly pressed by this manual operation, a negative pressure is applied within the diaphragm chamber 22 due to the suction action of the pump 62, so that even when the engine is not in operation, The fuel tank 36
The fuel inside is introduced into the diaphragm chamber 22 through the pump chamber 40 of the fuel pump 18.

Therefore, the pump 62 functions as a suction type primer pump, and when the diaphragm chamber 22 is filled with fuel, the suction fuel flows through the suction passage 94, the pump chamber 84, and the discharge passage 98 by subsequent repeated operations of the pump 62. After that, it is sequentially fed to the metering chamber 60.
When the liquid level of the fuel fed to this metering chamber 60 reaches a height defined by the discharge pipe 64, the excess amount of the fed fuel is discharged to the outside of the carburetor 10 via the discharge pipe 64.

As is clear from the above, the pump 6
By confirming the discharge of fuel from the discharge pipe 64, the operator 2 can know that a predetermined amount of fuel has been stored in the metering chamber 60, and at that point the operation of the pump 62 is stopped. Ru. Thereafter, the valve member 72 is pressed, and the opening 66 is opened by the pressure of the valve member 72. When the opening 66 is opened, a predetermined amount of fuel stored in the metering chamber 60 is released into the guide section 70 through the guide path 80.
and then flows to the holding means 58.

At this time, even if the discharge pipe 64 is clogged with fuel remaining in the pipe, since the leak passage 82 functions as a vent hole, the fuel in the metering chamber 60 will be removed. The water flows quickly and smoothly to the holding means 58 without remaining in the water. Further, the leak passage 82 is connected to the guide passage 80.
Since the leak passage 82 extends upwardly, the leak passage 82
No fuel will leak out.

Therefore, a predetermined amount of fuel that is sufficient to facilitate engine starting can be stored in the storage means 58 as auxiliary fuel. Since the air is sucked into the air supply port by negative pressure, the mixture concentration is appropriately increased, and as a result, the startability of the engine is improved.

In the auxiliary fuel supply mechanism 56 according to the present invention,
When fuel is supplied to the metering chamber 60 by operating the pump 62, the fuel flows into the metering chamber 60 with force, but the wall defining the metering chamber has a vent hole penetrating the wall. Since the vent hole is not formed, the fuel flowing into the metering chamber 60 will not flow out from the vent hole along its outer wall surface, and this flowing fuel will not adhere to the surface of the carburetor 10 or the surface of the internal combustion engine. There isn't. Further, the leak passage 82 functioning as a vent hole is cut off from communication with the metering chamber 60 when the pump 62 is operated, that is, when the valve device 68 is closed. Therefore, fuel will not flow out from the leak passage 82.

The adhesion of fuel to the surfaces of the carburetor 10 and the internal combustion engine described above is extremely dangerous as it can easily cause a fire because the engine becomes hot. The discharge pipe 6
Since the fuel discharged from 4 is guided to the outside of the carburetor 10 by this discharge pipe, this discharge pipe 6
The fuel discharged from 4 will not adhere to the carburetor 10 and the engine. However, in order to ensure further safety, it is desirable to return the fuel discharged from the discharge pipe to the fuel tank 36.

In the above description, an example was explained in which the opening 66 was opened and closed by the valve device 68.
Alternatively, a valve device as described above may be provided in the passage 80 to disconnect or disconnect the passage 80. In this case, as described above, the leak passage is formed so as to communicate with the passage on the downstream side of the fuel flow path from the valve portion of the valve device.

According to the present invention, as described above, by providing a metering chamber, a predetermined amount of fuel can be stored in the auxiliary fuel storage means by a simple operation, thereby starting the internal combustion engine. can be done with certainty.

Further, according to the present invention, when feeding fuel to the metering chamber, the operation can be carried out safely without causing spilled fuel to adhere to the vaporizer and the internal combustion engine, and moreover, the operation can be carried out safely from the metering chamber to the metering chamber. A predetermined amount of fuel can be quickly supplied to the storage means.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a carburetor to which an auxiliary fuel supply mechanism according to the present invention is applied. 10: carburetor, 12: intake path, 24: fuel supply mechanism, 56: auxiliary fuel supply mechanism, 58 (58a,
58b): Auxiliary fuel storage means, 60: Quantification chamber, 6
2: Auxiliary fuel feeding device, 64: Discharge pipe, 68: Valve device, 80: Guide path, 82: Leak passage.

Claims (1)

[Scope of utility model registration request] A mechanism for supplying auxiliary fuel to an internal combustion engine including a carburetor provided with a fuel supply mechanism to facilitate starting of the engine, the intake path leading to an air supply port of the engine via the carburetor. an auxiliary fuel storage means provided in the storage means; an auxiliary fuel feeding device; and the fuel feeding device receives fuel from the fuel feeding device and stores a predetermined amount of fuel to be supplied to the storage device. a metering chamber including a discharge pipe for discharging excess fuel fed from the metering chamber to the outside; a guide path for guiding the fuel in the metering chamber to the retention means;
a valve device that is opened to allow a predetermined amount of fuel in the metering chamber to flow out to the retention means prior to starting the engine; and when the valve device is opened, from the metering chamber to the retention means; a leak passage for an internal combustion engine, the leak passage having one end open to the guide passage downstream of the valve device of the guide passage and the other end opening to the atmosphere above the guide passage to allow fuel to flow out. Auxiliary fuel supply mechanism for.