JPS6143962Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is designed to be incorporated into the carburetor of a two-stroke engine installed as a drive source in a portable working machine such as a chain saw or brush cutter in order to facilitate the starting of the engine. The present invention relates to a preferred auxiliary fuel supply mechanism.

The applicant of the present application previously proposed in Utility Model Application No. 56-98470 and Utility Model Application No. 57-151815 that an auxiliary fuel retention means was provided in the intake passage of the internal combustion engine to facilitate the starting of the internal combustion engine. A metering chamber is provided for storing fuel to be delivered to the holding means, and a fixed amount of auxiliary fuel stored in the metering chamber is fed to the holding means prior to starting the engine. It was revealed that the auxiliary fuel retained in the engine is sucked into the engine as the engine starts, increasing the mixture concentration at the time of starting the engine, thereby making it easier to start the engine. .

By the way, in order to smoothly guide a certain amount of fuel stored in the metering chamber to the holding means, the metering chamber is positioned above the holding means in the attitude of the carburetor when the engine is started. Preferably, the metering chamber is formed in the upper part of a side plate made of synthetic resin material which is joined to the main body of the vaporizer at its side.

Therefore, the excess fuel fed to the metering chamber will be discharged to the outside of the carburetor from the discharge port opened at the upper part of the side plate, and there is a possibility that this discharged fuel may be applied to the carburetor. For this purpose, it is necessary to connect a pipe member to the discharge port and guide the discharged fuel downward through the pipe member.

In order to eliminate the need for the pipe member, it is conceivable to provide a guide path inside the side plate made of a synthetic resin material for discharging excess fuel discharged from the metering chamber from the lower part of the carburetor. , such a guide path has a long overall length, and it is technically difficult to form such a long guide path inside the side plate during molding of the side plate.

Therefore, an object of the present invention is to provide an internal combustion engine capable of guiding excess fuel from the metering chamber to the lower part of the carburetor and discharging it to the outside from the lower part of the carburetor without using the pipe member described above. The object of the present invention is to provide an auxiliary fuel supply mechanism.

The present invention focuses on the fact that a cover plate is connected to a side plate made of a synthetic resin material that is connected to a side part of a carburetor main body so as to cover the side plate, and the surface of the side plate that the cover plate of the side plate faces is a groove extending vertically in the groove, and a gap defined by the groove and the cover plate that closes the open surface of the groove as part of the discharge path for the excess fuel; Characterized by its use.

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

FIG. 1 shows an example in which the present invention is applied to a conventionally well-known diaphragm type carburetor 10.
and a side plate 18 made of a synthetic resin material coupled to one side of the carburetor body via a gasket 16;
A cover plate 22 is connected to one side of the side plate via a gasket 20. Vaporizer body 1
4 includes a rotary throttle valve 24 as a throttle valve for making the actual diameter of the air hole 12 variable.
is included. One end of the air hole 12 is connected to an air cleaner via an air pipe (not shown), and the other end is connected to, for example, an intake port of a two-cycle engine via an intake pipe (not shown). The air holes 12 constitute an intake passage.

The carburetor 10 is provided with a conventionally well-known fuel supply mechanism 26, which includes a fuel pump 28 provided in association with the carburetor body 14 and the side plate 18, and A diaphragm chamber 32 defined by a diaphragm 30 provided in the diaphragm 30 is provided.

Fuel pump 28 is a diaphragm pump having a diaphragm 34 and a pair of check valves 36,38. A diaphragm chamber 40 formed on one side of the diaphragm 34 receives the pulsating operating pressure of the engine, for example, the crank chamber pressure of a two-stroke engine. Thus, in operating conditions of the engine, the fuel pump 28 pumps fuel in the fuel tank (not shown) through the opening 42 and one check valve 36 to the other side of the diaphragm 34, as is well known in the art. The fuel is sucked into a pump chamber 44 formed in the diaphragm chamber 32, and the sucked fuel is forced into the diaphragm chamber 32 from the other check valve 38 through a passage 46.

The fuel in the diaphragm chamber 32 is moved to the check valve 4 by the intake negative pressure generated during the operation of the engine.
8 and an adjusting screw 50, the fuel is sucked into a conventionally well-known fuel nozzle (not shown) provided in association with the throttle valve 24, and from the nozzle to the air hole. 12. The diaphragm 30 also has a valve member 58 that opens and closes the passage 46 via a swing lever 56 that receives the spring force of a spring 45 in response to negative pressure acting on the diaphragm chamber 32.
Activate.

Therefore, in the operating state after the engine is started, the valve member 58 is opened to compensate for the fuel supplied to the engine from the fuel nozzle, so that a predetermined amount of fuel remains in the diaphragm chamber 32. Since this fuel is held and supplied to the engine as appropriate, the operation of the engine is suitably controlled according to the opening degree of the throttle valve 24. However, when starting the engine, the above-mentioned fuel from the fuel supply mechanism 26 alone cannot supply the engine with a rich mixture sufficient to improve its startability.

In order to improve the startability of this engine, the carburetor 1
0 is provided with an auxiliary fuel supply mechanism 60.

The auxiliary fuel supply mechanism 60 is a throttle valve 2 in the air hole 12 which constitutes a part of the intake passage.
The fuel storage unit 62 includes an auxiliary fuel storage means 62 provided upstream of the air hole 12, i.e., on the air cleaner side, a metering chamber 64 for temporarily storing a predetermined amount of fuel to be supplied to the main storage stage, and an auxiliary fuel supply device 66 for supplying fuel to the metering chamber. In the illustrated example, the storage means 62 comprises a recess 62a provided in the peripheral wall of the air hole 12 and a sponge-like water-absorbing member 62b held in the recess. The storage means 62 can be disposed downstream of the throttle valve 24.

As shown in FIG. 1, the quantitative chamber 64 is formed at the top of the side plate 18 so as to be located above the main holding stage in the attitude of the carburetor 10 when the engine is started. . Quantification room 6
4 opens into the air hole 12 above the retaining means 62 via an auxiliary fuel supply path 70 connected to a discharge port 68 provided at its lower part.

A manual valve device 72 for opening and closing the discharge port 68 is provided on the side plate 18, and the valve device is pressed toward a valve seat 76 of the discharge port 68 by the spring force of a spring 74. The discharge port 68 is closed by the valve body 78. Therefore, the discharge port 68 can be opened by the operator pushing in the valve body 78. The supply path 70 is provided with a vent hole 80 that opens to the outside of the carburetor above the valve device 72 in order to ensure smooth outflow of fuel from the metering chamber 64 to the storage means 65, which will be described later.

In the illustrated example, the feeding device 66 that feeds fuel to the metering chamber 64 is a suction type primer pump that is manually operated prior to starting the engine. This suction type primer pump 66 includes a side plate 18 and a cover plate 2 to define a pump chamber 82.
2, a hemispherical elastic body 84 is provided. The pump chamber 82 communicates with the diaphragm chamber 32 through an inlet passage 88 provided with a check valve 86, and with the metering chamber 64 through an exhaust passage 92 provided with a check valve 90 at the lower portion of the metering chamber.

Therefore, by repeatedly pressing the elastic body 84, a negative pressure can be applied to the diaphragm chamber 32, and this negative pressure can guide fuel into the diaphragm chamber 32 through the fuel pump 28 which is in an inoperative state. When the diaphragm chamber 32 is filled with fuel, the fuel sucked into the pump is fed to the metering chamber 64 through the exhaust passage 92 by the subsequent operation of the pump 66.

In order to discharge the excess amount of fuel fed to this metering chamber 64, the upper portion of the metering chamber 64 is clearly shown in FIG. As shown, an outlet 94 is provided. This discharge port 94 is connected to the side plate 1
It communicates with a discharge passage 96 extending from the upper part of the side plate 18 to the lower part thereof, which is formed in relation to the side plate 18 . The discharge passage 96 has a first passage portion 96a connected to the discharge port 94 at one end and formed inside the side plate 18.
and a second passage portion 96b connected to the passage portion and formed between the side plate 18 and the cover plate 22;
attributed to the discharge hole 98 that opens to the outside at the bottom of 8;
and a third passage portion 96c formed inside the side plate 18.

On the surface of the side plate 18 facing the cover plate 22, as shown in FIG.
A concave groove 100 for defining a passage portion 96b of the
has an opening 10 for receiving the elastic body 84.
It extends in the vertical direction of the side plate 18 along the outer periphery of the side plate 2 .
One end of the groove 100 opens to the first passage portion 96a, and the other end opens to the third passage portion 96c. Further, in the example shown in FIG. 3, a groove 104 for forming a part of the auxiliary fuel supply passage 70 and a groove 106 for forming a part of the exhaust passage 92 are formed.

The groove 100 cooperates with the cover plate 22 to define a gap serving as the second passage portion 96b. In order to improve the airtightness of this cavity 96b,
The aforementioned gasket 20 is disposed between the side plate 18 and the cover plate 22, and in order to enhance the sealing effect, gaskets 20 are provided on both sides of the groove 100, as shown in FIG. Rib part 1 along
It is desirable to provide 08. Further, as shown in FIG. 5, the edge of the elastic body 84 and the side plate 18
It is desirable to form a groove 112 having ribs 110 surrounding the opening 102 in order to improve the airtightness between the opening 102 and the opening 102 .

The discharge passage 96 guides the excess fuel to the lower part of the carburetor 10 when the liquid level of the fuel supplied to the metering chamber 64 exceeds the level of the discharge port 94 by operation of the pump 66. , is discharged from the discharge hole 98.

Therefore, by confirming the discharge of fuel from the discharge hole 98, the operator can know that a predetermined amount of fuel has been reserved in the metering chamber 64, and at that point, the operation of the pump 66 is stopped. be done. Thereafter, when the valve body 78 is pressed and the discharge port 68 is opened, a predetermined amount of fuel stored in the metering chamber 64 flows to the retention means 62 via the auxiliary fuel supply path 70.

At this time, since the supply path 70 is provided with a vent hole 80, the fuel in the metering chamber 64 quickly and smoothly flows to the retention means 62 without remaining in the metering chamber.

Therefore, a predetermined amount of fuel that is just the right amount to make it easier to start the engine can be stored in the storage means 62, and this auxiliary fuel is sequentially supplied to the engine as the engine starts. Because it is done,
The air-fuel mixture is appropriately increased, and as a result, the startability of the engine is improved.

Further, the discharge passage 96 for guiding the excess fuel discharged from the metering chamber 64 to the outside of the carburetor 10 opens to the outside of the carburetor at the lower part of the side plate 18, that is, the lower part of the carburetor 10. Excess fuel can be prevented from being applied to the carburetor 10 without using the pipe member as used in the carburetor. Therefore, manual operation of the valve device 72 and pump 66 is not hindered by the pipe member, and the valve device 72 and pump 66 can be easily operated.

According to the present invention, as described above, at least a part of the discharge path extending from the metering chamber to the outside of the vaporizer is
A relatively long passage can be formed inside the carburetor by defining the cavity formed by the concave groove formed in the side plate and the cover plate coupled to the side plate. Excess fuel discharged from the metering chamber can be discharged from the lower part of the carburetor to the outside without using the conventional pipe member.

Therefore, the pipe member can be made unnecessary,
As a result, the pipe member does not impede the engine starting operation, which facilitates the engine starting operation and also makes it possible to simplify the appearance of the carburetor.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a vaporizer according to the present invention, FIG. 2 is a cross-sectional view taken along the line - shown in FIG. 3, and FIG. FIG. 4 is a plan view showing the side plate shown in FIG. 2;
Figures 5 and 5 are cross-sectional views taken along the lines indicated in Figure 3, respectively. 12: Air hole (intake path), 14: Carburetor body,
18: side plate, 22: cover plate, 26: fuel supply mechanism, 64: quantitative chamber, 66: auxiliary fuel supply device, 72: valve device, 96: discharge path, 100:
Concave groove.

Claims (1)

[Scope of utility model registration request] An internal combustion engine comprising a carburetor provided with a fuel supply mechanism, including a carburetor body, a side plate made of a synthetic resin material bonded to the side of the carburetor body, and a cover plate covering and bonded to the side plate. an auxiliary fuel supply mechanism for supplying auxiliary fuel to the engine to facilitate starting of the engine; a metering chamber for storing a predetermined amount of fuel to be supplied to the holding means; a device for feeding auxiliary fuel to the metering chamber; a discharge passage extending from the metering chamber to discharge the fuel to the metering chamber; and a valve device for discharging the fuel in the metering chamber toward the retention means prior to starting the engine; The side plate is provided so as to be positioned above the holding means in the attitude of the vaporizer at the time, and the discharge passage is formed on a surface of the side plate that faces the cover plate, and extends from the top of the side plate toward the bottom. The vaporizer is opened to the outside at a lower part of the carburetor through an elongated concave groove,
Auxiliary fuel supply mechanism for internal combustion engines.