JPH0141888Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a blowback fuel return device for an engine carburetor, which can reliably prevent blowback fuel from the carburetor from entering the air cleaner without increasing intake resistance. provide something.

The present invention has, for example, the first
As shown in FIG. 5 or 7, the engine E
An air cleaner 1 is disposed in front of the carburetor 5, and a purified air outlet 4 is provided at the end wall 3 of the case 2 of the air cleaner 1.
The clean air outlet 4 is connected to the inlet 7 at the front end of the mixing chamber 6 of the carburetor 5, and the end wall 3 of the case 2 of the air cleaner 1 and the cleaner element 8 are spaced apart from each other in the front and back. A blowback fuel return plate 12 is provided in a space 10 formed between the end wall 3 and the cleaner element 8 to prevent blowback fuel flowing back from the mixing chamber 6 of the carburetor 5 into the case 2 of the air cleaner 1. The blown-back fuel is captured by a return plate 12 and returned to the mixing chamber 6 of the carburetor 5.

The conventional blowback fuel return device is shown in Figs. 5 and 6.
As shown in the figure, a flat plate-shaped blowback fuel return plate 1 is provided between a clean air chamber 21 formed inside a doughnut-shaped paper cleaner element 8 and a clean air guide space 10.
2 is set upright, the plate surface corresponding to the mixing chamber inlet 7 of the vaporizer 5 is sealed, and a plurality of through holes 22 are made in the other plate surface to send outside air from the clean air chamber 21 into the vaporizer 5. The fuel blown back from the carburetor 5 enters the clean air guide space 10 from the clean air outlet 4, but is mainly blown into the fuel return plate 12 facing the opposite side of the mixing chamber inlet 7. After hitting and adhering to the plate surface, it is sucked back to the carburetor side with the next intake.

However, during high-load operation, the amount of fuel blown back from the return plate 12 increases, passes through the return plate and accumulates in the cleaner case 2, flows back into the clean air chamber, and clogs the cleaner element 8. There were many times when I let it happen.

Therefore, as shown in FIG. 7, there is a system in which a discharge path 50 for the adhering fuel is formed along the fuel return plate 12 to smoothly discharge the fuel to the outside of the cleaner case 2 and eliminate the accumulation inside the case. , the fuel may stain the outside of the case or cause a flame.

Moreover, in the above conventional example, the part of the fuel return plate 12 corresponding to the inlet of the mixing chamber, which is likely to receive fuel blowback directly, is sealed, and the through hole with the clean air chamber is eliminated from this sealed part. Since the opening is limited to the areas where the combustion chamber is opened, there is a problem in that the intake resistance increases and the amount of air-fuel mixture into the combustion chamber decreases.

Further, the carburetor disclosed in Utility Model Application Publication No. 54-155014 (see Fig. 8) has a cleaner case terminal wall 3
A tongue-shaped blowback fuel return plate 12 is attached to the back plate 12 so that the blowback fuel is received by the return plate 12 and does not reach the cleaner element 8. Therefore, when the engine is operated at high speed, the amount of blowback increases and exceeds the return plate 12, causing the cleaner element 8
There was an extremely high risk of being blown away.

This invention solves the above problems,
By catching the blowback fuel with the blowback fuel return plate and returning it to the carburetor side, the cleaner element is not clogged with blowback fuel, and
It was proposed for the purpose of minimizing intake resistance, and to achieve this purpose, it is constructed as follows (numerals are illustrated in FIGS. 1 and 2).

That is, a blowback fuel receiving chamber 14 is formed between the blowback fuel return plate 12 and the case end wall 3 above the clean air outlet 4, and the blowback fuel return plate 12 has its lower end 13 connected to the mixing chamber inlet 7. The space 16 on the front side of the bench lily hole 15 of the mixing chamber 6 is formed in an inclined shape protruding inward.
is covered with a blowback fuel return plate 12, and a ventilation gap 20 is provided between the lower peripheral edge 17 of the blowback fuel return plate 12 and the lower peripheral surface 18 of the mixing chamber 6.

Therefore, the effects of the present invention brought about by the above configuration will be described below. Since it is covered with a return plate, the returned fuel is received by the return plate and guided to the lower tip side of the return plate, and during the next intake, it is carried on the intake air from the air cleaner and the fuel adhering to the return plate is reliably and quickly transferred to the carburetor side. can be returned to.

Therefore, it is possible to completely prevent blowback fuel from adhering to the air cleaner, eliminate clogging of the cleaner element, and maintain smooth cleaner performance.

Furthermore, since there is a sufficient ventilation gap between the lower circumferential edge of the fuel return plate and the lower circumferential surface of the mixing chamber, an intake passage is secured, making it easier for intake air to flow from the air cleaner into the carburetor, and reducing intake resistance. can be minimized.

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a longitudinal sectional front view of the main parts of the paper air cleaner and carburetor, Fig. 2 is a sectional view taken along the - line in Fig. 1,
FIG. 3 is a perspective view of the blowback fuel return plate, in which the carburetor 5 and the air cleaner 1 are sequentially attached to the intake port of the engine E, and the air cleaner 1 is attached to the cleaner case 2, the cleaner element 8, and the intake pipe 2.
It consists of 3.

The cleaner case 2 is a cylindrical case body 2.
4 and a back cover 25, a donut-shaped cleaner element 8 made of paper bent into a bellows shape is arranged inside the case body 24, a dust removal sponge material 26 is placed along the outer periphery of the cleaner element 8, and a purifying air chamber is provided inside the donut-shaped cleaner element 8. Form 21.

The dust removal sponge material 26 and the case body inner peripheral surface 2
An intake swirl space 29 is provided between the air intake tube 8 and the air intake tube 29, and one end of this swirl space 29 is connected to the intake tube 23. It passes through the cleaner element 8 and leads to the clean air chamber 21.

In addition, a partition wall 27 is interposed between the case body 24 and the back cover 25, and both are connected with shrimp metal fittings (not shown).
At the same time, a plurality of ventilation holes 22 are provided across the surface of the partition wall 27 facing the clean air chamber 21.

The back cover 25 protrudes toward the back and has a clean air guiding space 10 inside thereof. The purified air guide space 10 is expanded further upward.

Then, the clean air outlet 4 is connected to the inlet 7 at the front end of the mixing chamber of the carburetor 5, and a blowback fuel return plate 12 is arranged in an inclined manner across the clean air guide space 10, and its upper end is fixed to the partition wall 27. Then, its lower end is thrust into the mixing chamber inlet 7.

The blowback fuel return plate 12 has a tongue shape that protrudes toward the carburetor 5 side, and has a storage wall 30 raised all around its outer periphery 17 to store blowback fuel adhering to the return plate 12. Flat groove portion 31 surrounded by wall 30
The structure is such that the amount of water is kept within the range of 100 to 100%, so that the water does not flow back into the cleaner element 8.

In addition, the inclined surface portion 32 of the fuel return plate 12 facing the mixing chamber 6 allows the front space 1 of the bench lily hole 15 to
6 and the lower peripheral edge 17 of the return plate 12.
A ventilation gap 20 is provided between the mixing chamber 6 and the lower circumferential surface 18 of the mixing chamber 6, and the upper half where the return plate 12 partitions the clean air guide space 10 above the ventilation gap 20 serves as a blowback fuel receiving chamber 14. .

To describe the function of the blowback fuel return device constructed in this way, the clean air flowing out from the clean air chamber 21 into the clean air guide space 10 through the ventilation holes in the partition wall 27 is transferred between the fuel return plate 12 and the mixing chamber 6. The vaporizer mixing chamber 6 is supplied from the ventilation gap 20 between the two. However, on the other hand, if there is blowback from the main jet 33 of the carburetor 5,
A blowback fuel receiving chamber 14 located at the rear of the carburetor 5
The blowback fuel tries to blow toward the air cleaner 1 on the airflow flowing into the air cleaner 1, but it is blocked by the fuel return plate 12 that occupies the inlet side of the carburetor mixing chamber 6, and the fuel is blown into the flat groove part 31 of the return plate. After adhering, it is sucked back into the carburetor 5 during the intake process of the engine E.

Therefore, the blowback fuel is cut off by the return plate 12 and does not reach the cleaner element 8, and clogging of the element can be reliably eliminated.

As described above, the present blowback fuel return device is characterized in that the blowback fuel is captured by the return plate without increasing intake resistance and prevented from reaching the cleaner element, so the shape of the fuel return plate is The air cleaner itself does not have to be shaped like a tongue with its periphery raised up as in the above embodiment, but may also be a smooth plate shape (see Fig. 4).
Needless to say, it may be a sponge type, and it does not matter if it is a dry type, an oil type, or a wet type.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional front view of the main parts of a paper air cleaner and a carburetor, FIG. The figure is a perspective view of the blowback fuel return plate, Figure 4 is a view equivalent to Figure 3 showing another embodiment, Figure 5 is a view equivalent to Figure 1 showing a conventional example, and Figure 6 is a view equivalent to the same conventional example. A diagram corresponding to FIG. 2, FIG. 7, and FIG. 8 are diagrams corresponding to FIG. 1 showing other conventional examples. 1...Air cleaner, 2...Case, 3...2
end wall, 4...purified air outlet, 5...carburizer, 6...
...Mixing chamber, 7...Inlet of 6, 8...Cleaner element, 10...Space between 3 and 8, 12...Fuel return plate, 13...Lower end of 12, 14...
Blowback fuel receiving chamber, 15... Bench lily hole, 16
...15 front space, 17...12 lower periphery, 1
8... lower peripheral surface of 6, 20... ventilation gap between 17 and 18, E... engine.

Claims (1)

[Scope of Claim for Utility Model Registration] The air cleaner 1 of the engine E is disposed in front of the carburetor 5, and the end wall 3 of the case 2 of the air cleaner 1 is
Open a clean air outlet 4 and connect this clean air outlet 4 to the vaporizer 5.
is connected to the inlet 7 at the front end of the mixing chamber 6 of the air cleaner 1, and the end wall 3 of the case 2 of the air cleaner 1 and the cleaner element 8 are arranged separated from each other in the front and back, so that a A blowback fuel return plate 12 is provided in the space 10 where the blowback fuel flows back from the mixing chamber 6 of the carburetor 5 toward the case 2 of the air cleaner 1, and the blowback fuel return plate 12 captures and vaporizes the blowback fuel. In an engine carburetor blowback fuel return device configured to return fuel to a mixing chamber 6 of a container 5, blowback fuel is returned between a blowback fuel return plate 12 and a case end wall 3 above the clean air outlet 4. A receiving chamber 14 is formed, a blowback fuel return plate 12 is formed in an inclined shape with its lower end 13 protruding into the mixing chamber inlet 7, and a front space 16 of the bench lily hole 15 of the mixing chamber 6 is formed as a blowback fuel return plate. 12, and a ventilation gap 20 is provided between a lower peripheral edge 17 of a blowback fuel return plate 12 and a lower peripheral surface 18 of a mixing chamber 6.