JPH08319889A - Foaming preventing device for float chamber of carburettor - Google Patents

Abstract

PURPOSE: To eliminate cause of spewing by furnishing a needle valve for measuring the fuel working with a float, and precluding the fuel measured by the needle valve and containing bubbles from being beaten to the fuel liquid surface to cause further bubbling. CONSTITUTION: The flow speed of a fuel measured by a seat part 6b and a valve 7a falls at a fuel sump 6d. There the bubbles are separated from the fuel and rise through a bubble release hole 18 to over it. The remaining liquid- phase fuel flows out from a fuel outflow port 17 downward and drops onto the fuel liquid surface H.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a float chamber foam prevention device for a carburetor for an internal combustion engine.

[0002]

2. Description of the Related Art A needle valve of a vaporizer shown in FIGS. 2 to 4 is known from Japanese Utility Model Laid-Open No. 58-181964.

In this prior art, a needle valve holder 6 having an inflow port 5 is attached to a fuel passage 3 above a float chamber 2,
The needle valve portion 8 is provided in the needle valve holder 6 so that the inlet 5
In the needle valve into which the valve body 7 for opening and closing the valve is inserted, a large number of fuel outlets 14 are bored in the peripheral wall portion 6a of the needle valve holder 6,
A guide groove 15 for guiding fuel is formed between the needle valve portion 8 of the valve body 7 and the fuel outlet port 14.

1 is a carburetor main body, 4 is a needle valve mechanism, 9 is a spring, 10 is a valve shaft, 11 is a float, 12 is a float arm, and 13 is a needle valve receiver.

[0005]

SUMMARY OF THE INVENTION In the above conventional technique,
The fuel from the fuel passage 3 is metered by the needle valve mechanism 4 and then depressurized to generate bubbles. Bubbles are often generated especially during high-speed operation, and the fuel thus bubbled is struck on the liquid surface of the fuel (gasoline) in the float chamber 2 to further grow bubbles.

The grown air bubbles blow out from the inner vent into the intake passage to enrich the air-fuel mixture, which causes spewing leading to misfire. Therefore, an object of the present invention is to provide a float chamber bubbling device for a vaporizer that can solve the above problems.

[0007]

In order to achieve the above object, the invention of claim 1 has a needle seat (6A) and a float (11) for metering the fuel flowing in from a fuel passage (3). ) And a needle valve (7A) interlocking with the needle seat (6A).
And a valve part (7a) of the needle valve (7A), which constitutes a metering part (16), in a downstream of the needle seat (6A) and the valve part (7a) of the needle valve (7A). A float chamber bubbling prevention device for a carburetor, characterized in that a fuel pool (6d) is provided in a portion thereof, and a hole (18) for allowing bubbles to escape from the fuel pool (6d) is provided in the valve seat (6A).

In the present invention, the fuel metered by the metering section (16) enters the fuel pool (6d) and its flow velocity decreases, and the bubbles mixed with the liquid phase fuel are separated to release the bubbles (1
Escape from 8).

Only the liquid-phase fuel from which the air bubbles have been separated in this way flows out from the fuel pool (6d) and falls onto the liquid surface of the fuel in the float chamber. According to a second aspect of the present invention, in the float chamber bubbling prevention device for a carburetor according to the first aspect, a bubble escape hole (18) is formed obliquely upward from a ceiling (6f) of the fuel pool (6d). It is characterized by.

According to the present invention, in addition to the function of the first aspect of the invention, only the bubbles separated by the fuel pool (6d) pass through the holes (18) for allowing the bubbles to escape from the ceiling (6f) of the fuel pool (6d). It flows upwards.

According to a third aspect of the present invention, in the device for preventing foam formation in the float chamber of the carburetor according to the second aspect, the needle seat (6A) is formed from the seat portion (6b) and the inner diameter of the seat portion (6b) in this order from above. Guide part (6c) with a large inner diameter to guide the needle valve (7A) so that it can move up and down.
A fuel outlet (6d) having an inner diameter larger than the inner diameter of the guide portion (6c) and an outer periphery of the needle valve (7A) having an inner diameter smaller than the inner diameter of the fuel reservoir (6d). (17) and the bottom part (6e) which comprises it, It is characterized by the above-mentioned.

In the present invention, the fuel metered by the metering section (16) passes between the outer circumference of the needle valve (7A) and the inner circumference of the guide section (6c) of the needle seat, and the fuel pool ( 6d), the flow velocity decreases. And the hole (18) where only the bubbles are separated in the fuel pool (6d) and the bubbles escape
Flows upwards through. The remaining liquid-phase fuel flows out from the fuel outlet (17) and drops to the fuel level (H) in the float chamber (2).

[0013]

1 (a) and 1 (b) show an embodiment of the present invention, 1 is a carburetor body, 2 is a float chamber, 3 is a fuel passage, 6A is a needle seat, 7A is a needle valve, and 9 is A spring 10 inserted between the needle valve 7A and the valve shaft 10.
Is a valve shaft mounted on the needle valve 7A so as to be relatively slidable in the vertical direction, 11 is a float, 12 is a float arm, and 13 is a needle valve receiver.

Further, the seat portion 6 of the needle seat 6A
b and the conical surface of the needle valve 7A, the valve body portion 7a
And constitute the measuring unit 16. The needle seat 6A has a guide portion 6c having an inner diameter larger than the inner diameter of the seat portion 6b in order from the seat portion 6b having the smaller inner diameter downward.
And a bottom portion 6 which forms a fuel outlet 17 between the fuel reservoir 6d having an inner diameter larger than that of the guide portion 6c and the outer periphery of the needle valve 7A having an inner diameter smaller than that of the fuel reservoir 6d.
e and.

The bottom portion 6e is a needle having a substantially cylindrical shape as a whole.
It consists of an annular plate made separately from the seat 6A, and this is fitted and fixed to the inner periphery of the lower end of the cylindrical portion of the needle seat 6A, but the cylindrical portion of the needle seat 6A and the bottom portion 6e are made of one material. May be integrally formed.

Reference numeral 18 denotes a plurality of holes penetrating the needle valve 6A from the ceiling 6f of the fuel pool 6d and opening obliquely upward, and these holes 18 function as holes for releasing bubbles. Reference numeral 19 is a well-known inner vent provided in the vaporizer main body 1, and 20 is a float chamber 2.
A plate for preventing air bubbles generated therein from entering the intake passage through the inner vent 19, and 21 is a union nipple for introducing fuel into the fuel passage 3 from a fuel pump (not shown).

In the above-described embodiment, the fuel metered by the metering section 16 from the union nipple 21 through the fuel passage 3 passes between the inner circumference of the guide section 6c and the needle valve 7A. The fuel enters the fuel pool 6d, where the bubbles separate from the liquid-phase fuel and rise upward through the holes 18 through which the bubbles escape.
It flows to the upper part of the float chamber 2.

The separated liquid-phase fuel drops downward from the fuel outlet 17 and drops to the fuel liquid level H, and a part of the liquid-phase fuel dives downward from the liquid surface.

[0019]

EFFECTS OF THE INVENTION Since the float chamber bubbling prevention device of the carburetor of the present invention is configured as described above, only the liquid fuel separated from the bubbles in the fuel pool is discharged to the fuel level (H) in the float chamber. Since it drops, it is possible to prevent foaming on the liquid surface of the fuel due to the inflow of fuel into the float chamber, and there is an advantage that spewing does not occur.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention, (a) is a longitudinal sectional view, (b)
It is a principal part enlarged view of the same figure (a).

FIG. 2 is a vertical cross-sectional view of a conventional technique.

FIG. 3 is an enlarged view showing a part of the conventional technique of FIG.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

[Explanation of symbols]

 1 vaporizer main body 2 float chamber 3 fuel passage 6A needle seat 6b seat portion 6c guide portion 6d fuel sump 6e bottom portion. 6f Ceiling 7A Needle valve 7a Valve part (valve body) 11 Float 16 Measuring part 17 Fuel outlet 18 Bubble escape hole H Fuel liquid level

Claims (3)

[Claims] 1. A meter having a needle seat and a needle valve interlocking with a float for metering fuel flowing from a fuel passage, and metering with a seat part of the needle seat and a valve part of the needle valve. In the vaporizer constituting the part, the fuel seat is provided in a portion of the needle seat and a portion of the needle valve downstream of the valve portion, and the valve seat is provided with a hole for allowing bubbles to escape from the fuel reservoir. Float chamber foam prevention device. 2. A hole for letting bubbles escape is formed obliquely upward from the ceiling of the fuel pool.
Float chamber froth prevention device of the vaporizer described. 3. The needle seat includes a seat portion in order from above, a guide portion having an inner diameter larger than the inner diameter of the seat portion to guide the needle valve so that the needle valve can move up and down, and an inner diameter larger than the inner diameter of the guide portion. 3. The carburetor according to claim 2, further comprising: a fuel reservoir having the fuel reservoir, and a bottom portion having an inner diameter smaller than an inner diameter of the fuel reservoir and forming a fuel outlet with the outer periphery of the needle valve. Float chamber foam prevention device.