JPS6042200Y2 - Carburetor for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor for an internal combustion engine, and in particular to an improvement of a carburetor for an internal combustion engine for the purpose of improving fuel atomization in an idle system.

Conventionally, in the slow system of this type of carburetor, as shown in FIG. A large-diameter blind hole 5 forming a bypass passage is bored horizontally at the lower end of 3.

A small-diameter bypass hole 6 is provided at the end of this blind hole 5, and the side opposite to the bypass hole 6 is closed with a blind plug 7, and an expansion chamber 8 is formed between these holes 6 and the blind plug 7. It is now possible to do so.

Further, a hole 9 forming an idle passage is drilled diagonally across the expansion chamber 8 of such a blind hole 5, and an idle hole 10 is provided downstream of the throttle valve 4 beyond the hole 9. An adjustment screw 11 is screwed into the engine, and the gap between these holes 10 and the tip 11' of the adjustment screw 11 is adjusted to set the amount of fuel sucked out during idling to a predetermined value.

Therefore, in such a structure, fuel from the slow fuel passage 3 passes through the expansion chamber 8 having a large volume and enters the bypass hole 6.
Since the fuel flows into the idle hole 10, the atomization of the fuel is poor.

Further, fuel is accumulated in droplets in the expansion chamber 8, and during idling operation, the droplets flow out due to the negative pressure from the idle hole 10 and mix with a small amount of air, resulting in very poor atomization.

As a result, problems arise in that idling is unstable and the exhaust gas contains a large amount of CO, resulting in poor fuel efficiency.

However, as an example of prior art that attempts to solve the above problem, as described in Japanese Patent Application Laid-Open No. 52-97036, an air passage that supplies air from the atmosphere side to the idle hole is connected to the slow fuel system. There is a system in which the leading end opening of the idle nozzle is located within the air passage, but according to this, the fuel from the fuel passage of the slow fuel system passes through an expansion chamber with a large volume. Since the fuel flows through the bypass hole and the idle hole, fuel atomization is not sufficient during idling or low-load operation, and the opening of the throttle valve changes from idling to low-load operation. The disadvantage is that the fuel connection does not become smooth even when the amount of fuel increases.

The present invention was developed to solve the above-mentioned problems and drawbacks, and the fuel passage of a slow fuel system is divided into a bypass passage with a substantially uniform passage area and an idle passage with a nearly uniform passage area. Branching in an inverted V shape to eliminate mutual interference of fuel flows in these passages,
A carburetor for internal combustion engines that eliminates the expansion chamber and eliminates the accumulation of fuel droplets, improves fuel atomization, improves fuel efficiency, improves exhaust gas purification, and allows the above-mentioned fuel to flow smoothly. It provides:

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

Fig. 2 shows an embodiment of the present invention, in which reference numeral 1 indicates a part of the carburetor body near the throttle valve 4, where the lower end 3' of the slow fuel passage 3 formed perpendicularly thereto is bypassed. It is stopped at a high position on the upstream side of the hole, and this lower end 3
A bypass passage 12 having a substantially uniform passage area is diagonally drilled from ' to the bypass hole side, and an idle passage 13 having a substantially uniform passage area branching from the bypass passage 12 is perpendicularly bored.

In addition, immediately upstream of the minimum opening position of the throttle valve 4, there is a
In order to form a bypass hole, a relatively large diameter hole 14 is drilled horizontally up to just before the air-fuel mixture passage 2, and a small diameter bypass hole 6 is formed by passing a drill or the like through this hole 14.

After forming the bypass hole 6 in this way, the hole 14 is again
The blind plug 15 is filled with a blind plug 15, and as shown in FIG. At the same time, holes 17 and 18 are bored at positions corresponding to the idle passage 13 and the hole 9 into which the adjustment screw 11 is screwed, and these holes 17 and 18 have only the converging waist hole 18 inside. A stepped portion 19 is formed by reducing the diameter and penetrates diagonally toward the idle hole 10 side.

Thus, when such a blind stopper 15 is packed, the bypass passage 12 communicates with the bypass hole 6 through the groove 16, and the idle passage 13 communicates with the hole 9 in a straight line through the hole 17 to provide the adjustment screw 11. and will be connected to 18.

Further, on the downstream side of the throttle valve below the blind plug 15, an idle hole 10 communicating with the mixture passage 2 is provided horizontally. A hole 20 is diagonally drilled between the blind plug 15 and the hole 20 after the step 19 of the hole 18 of these blind plugs 15.
An idle nozzle 21 is fitted into the idle hole 10 through the.

Here, the idle nozzle 21 has a tip opening 21' protruding into the idle hole 10 and facing almost the center thereof, and the tip of the adjusting screw 11 is loosely fitted into the opening on the opposite side of the nozzle 21 to adjust the flow rate. It is supposed to be adjusted.

Furthermore, a hole 22 having a larger diameter than the hole 10 is connected to the side opposite to the mixture passage 2 of the idle hole 10, and a hose 24 forming a bypass air passage from the air cleaner 23 is inserted into this hole 22. There is.

Since the present invention is configured as described above, the fuel from the slow fuel passage 3 is divided into two parts and flows separately into the bypass passage 12 and the idle passage 13, and these passages 12 and 13 are substantially a passage. Since the area is uniform, the flow reaches the bypass hole 6 and the idle hole 10 without causing a decrease in flow velocity along the way.

When the throttle valve 4 is slightly open and the load is low, negative pressure acts on the bypass hole 6, and the negative pressure sucks out the fuel from the bypass passage 12 through the bypass hole 6, thereby preventing its atomization. get well.

On the other hand, during idling with the throttle valve 4 fully closed, suction pipe negative pressure acts on the idle hole 10, so fuel from the idle passage 13 is sucked out from this hole 10 via the idle nozzle 21, and air from the air cleaner 23 is sucked out from the idle passage 13. is also sucked out via the hose 24.

By the way, the idle hole 10 is narrower than the hose 24 of the air passage, and the hole 10 is further narrowed by the protrusion of the idle nozzle 21, so the air from the hose 24 flows through the idle hole 10 at high speed. .

Therefore, the fuel sucked out from the idle nozzle 21 rides on the high-velocity airflow and is ejected into the mixture passage 2 in a sonic state, resulting in very good atomization.

As described above, according to the present invention, there is no need for an enlarged portion as in the conventional case, and the passage areas of the bypass and idle passages 12 and 13 are substantially equalized, so that there is no reduction in flow velocity.
Atomization is improved and there is no interference between the passages 12 and 13.

Furthermore, since there is no expanded portion, fuel droplets will not accumulate there and be sucked out into the air-fuel mixture passage.

Therefore, the fuel sucked out from the bypass hole 6 is well atomized, and since the idle hole is narrowed by the protrusion of the idle nozzle, the air from the air passage flows through the idle hole at high speed, so that the air from the idle hole 10 flows through the idle hole at high speed. The fuel that is sucked out is ejected in a sonic state by a high-velocity air stream, resulting in very good atomization.

These advantages stabilize idling and reduce C.
O2 is reduced and fuel efficiency is improved.Furthermore, as the opening of the throttle valve increases from idling operation to low-load operation, the fuel flow can be made smoother, and driving performance can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a part of a conventional carburetor for an internal combustion engine.
FIG. 2 is a sectional view showing an embodiment of a carburetor for an internal combustion engine according to the present invention, and FIG. 3 is a perspective view showing the shape of a blind plug. 1... Carburetor body, 2... Mixture passage, 3... Slow fuel passage, 4... Throttle valve, 5... Blind hole, 6... Bypass hole, 7... Blind plug, 8... Expansion chamber, 9... Hole, 10... Idle Hall, 11...adjustment screw, 12...bypass passage, 13...idle passage, 14...
... hole, 15 ... blind plug, 16 ... groove,
17, 18...hole, 19...step, 2
0...L21...Idle nozzle, 2
...hole, 23 ... air cleaner, 24
······hose.

Claims (1)

[Scope of utility model registration request] In a carburetor equipped with a main fuel and a slow fuel system, the slow system fuel passage is divided into a bypass passage with a substantially uniform passage area and an idle passage with a nearly uniform passage area in an inverted V.
These passages are connected to a bypass hole located upstream of the throttle valve and to an idle hole located downstream of the throttle valve via an idle nozzle. An air passage supplying air from the atmosphere side is connected to the opposite side of the passage, and the tip opening of the idle nozzle is connected to the air passage.
A carburetor for an internal combustion engine, characterized in that the carburetor protrudes into the idle hole.