JPH0291465A - Emulsion tube in carburetor - Google Patents

Abstract

PURPOSE:To surely enable starting in a short time and to remarkably improve re-startability by providing a cone at the lower end of an emulsion tube, the top of which is a rounded-corner surface and positioning the cone a little lower than a ceiling surface in a fuel passage. CONSTITUTION:A cone 19 is solidly molded at the lower end of an emulsion tube 16, the top f of the cone is forced as a rounded-corner surface 19a with a suitable radius, and the cone is positioned a little lower than a ceiling surface 10a of a lateral fuel passage 10 by a distance (e). In this arrangement, air bubbles which are about to flow from a lateral fuel passage 10 into a main well 5, temporarily stay in the rounded-corner portion 19a in the contacting state and the air bubbles are pressed to the rounded-corner portion 19a by buoyancy of the air bubbles themselves. Thus, the air bubbles are directed to the whole of the outer peripheral surface of the emulsion tube 16 and broken into smaller air bubbles to flow in the interior of the main well 5, and a phenomenon of pushing out a large amount of fuel through a nozzle is reduced by the air bubbles to prevent over-rich of air-fuel ratio at the time of restarting and improve the startability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for supplying fuel to a main nozzle in a carburetor.
The present invention relates to an improvement in an emulsion tube for forming an emulsion by mixing with air.

[Conventional technology]

In the carburetor, the emulsification of the fuel to the main nozzle is carried out in a main well, the lower part of which communicates with the float chamber via the main jet and the upper part of which communicates with the main fuel passage to said main nozzle, with an air bleed at the upper end. Insert a porous emulsion tube into which air is introduced from the air bleed at the upper end.
From the many small holes in the emulsion tube,
The method of ejecting the emulsion into an annular emulsion chamber between the outer periphery of the emulsion tube and the main well is described in Japanese Utility Model Application Publication No. 54-4432, for example.
This is well known as described in Publication No. 3, etc.

[Problem to be solved by the invention]

However, when a horizontally extending fuel passage, such as a slow system fuel passage, is connected to the lower part of the main well, there is no fuel vapor in this horizontal fuel passage when the operation of the internal combustion engine is stopped. This vapor accumulates in the horizontal fuel passage and grows into large bubbles.
When these large bubbles flow into the emulsion chamber all at once, a large amount of fuel is forced out of the main nozzle (this is called percolation), so the internal combustion engine is restarted. When starting the engine, the air-fuel ratio was too rich and it took a long time to restart.

The present invention aims to solve this problem.

[Means to solve the problem]

In order to achieve this object, the present invention has a lower portion that communicates with the float chamber via the main jet and also communicates with a fuel passage that extends substantially laterally, such as a slow system fuel passage,
In a vaporizer comprising an emulsion tube inserted into a main well whose upper part communicates with a main fuel passage to a main nozzle, a downwardly tapered conical body is integrally provided at a lower end of the emulsion tube, The top of the cone is formed on an outer circumferential surface of an appropriate radius, and this outer circumferential surface is
The structure is such that the fuel passage is located at a position slightly below the ceiling surface of the horizontal fuel passage.

[For production]

When the internal combustion engine is stopped, vapor bubbles accumulated on the ceiling surface in the horizontal fuel passage flow into the annular emulsion chamber between the outer periphery of the emulsion tube and the inner periphery of the main well.

At this time, a downwardly tapered cone is integrally provided at the lower end of the emulsion tube, and the top of the cone is formed into an outer circumferential surface with an appropriate radius, and this outer circumferential surface is connected to the horizontal fuel passage. By configuring the structure to be located at a portion slightly below the ceiling surface of the cone, air bubbles attempting to flow into the emulsion chamber from the sideways fuel passage are in contact with the rounded corners of the cone and are located at the portion that is slightly below the ceiling surface. The bubble temporarily remains in the bubble and is pressed against the rounded corner due to the bubble's own buoyancy.

As a result, the air bubbles break up into small air bubbles around the entire circumference of the emulsion tube and flow into the emulsion chamber, so that the air bubbles in the sideways fuel passage become large air bubbles. It is possible to prevent percolation from occurring due to the emulsion flowing into the emulsion chamber all at once.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates a carburetor main body, in which an intake passage 2 and a float chamber 3 are formed. is provided with a throttle valve 4.

Reference numeral 5 indicates a main well formed in the carburetor main body 1 to extend in the vertical direction, and the upper part of the main well 5 is connected to a main fuel passage 8 to a main nozzle 7 in a pentier area 6 in the intake passage 2. communicate through, and also
A lower portion of the main well 5 communicates with the float chamber 3 via a main jet 9, and a fuel passage 10 extending laterally communicates with the lower portion of the main well 5.

This horizontal fuel passage 10 communicates with a slow port 13 at the throttle valve 4 and a slow system fuel passage 15 to the idle boat 14 via a vertical passage 12 containing a slow jet tube 11.

Reference numeral 16 indicates an emulsion tube inserted into the main well 5. The emulsion tube 16 is provided with a large number of small holes 17 and an air bleed 18 at its upper end.

A cone 19 is integrally formed at the lower end of the emulsion tube 16, and the top of the cone 19 is formed into an outer circumferential surface 19a with an appropriate radius, and this outer circumferential surface 19a is connected to the horizontal fuel. It is located at a location below the ceiling surface 10a in the passageway IO by a slight dimension (e).

If the internal combustion engine continues to operate for a while, the temperature of the carburetor main body 1 becomes high. Therefore, if the internal combustion engine is stopped in this state, there will be a temperature inside the horizontal fuel passage 10 in the carburetor main body 1 due to evaporation of fuel. Vapor is generated, this vapor becomes bubbles, and the ceiling surface 10 in the fuel passage 10 is
The vapor bubbles that accumulate in the part a, enter the main well 5.
and the emulsion tube 16 inserted into the annular emulsion chamber.

In this case, according to experiments, the emulsion tube 1
If the configuration is such that a simply shaped cone is provided at the lower end of the fuel well 5 as shown by the two-dot chain line in FIGS. 3 and 4, fuel will flow into the main well 5 from the horizontal fuel passage 10. The bubbles do not stay at the sharp top of the cone, but instead flow into the main well 5 as large bubbles, causing percolation, which takes time to restart the internal combustion engine. Ta.

On the other hand, as mentioned above, emulsion tube 1
A cone body 19 is integrally formed at the lower end of the cone body 19, and the top of this cone body 19 is formed into a rounded corner surface 19a with an appropriate radius, and this rounded corner surface 19a is connected to the horizontal fuel passage 1.
If the configuration is such that the air bubbles trying to flow into the main well 5 from the horizontal fuel passage 10 are located at a portion below the ceiling surface 10a by a slight dimension (8), the conical body 19 The bubbles temporarily remain at the point in contact with the rounded corner portion 19a, and are pressed against the rounded corner portion 19a due to their own buoyancy, so that the bubbles move around the outer periphery of the emulsion tube 16. Since the fuel flows into the main well 5 while breaking up into small bubbles around the entire circumference of the surface, it is possible to reduce the phenomenon in which a large amount of fuel is pushed out of the main nozzle by the bubbles, that is, percolation, which reduces the air-fuel ratio when restarting the internal combustion engine. This made it possible to prevent over-richness and improve startability.

In addition, according to experiments, the rounded corner part 1 of the cone body 19
It is preferable that the protruding dimension (e) of 9a is approximately 8 to 25% of the inner diameter (D) of the lateral fuel passage 10, and most preferably 15% of the inner diameter (D>) of the lateral fuel passage 10. It was around %.

〔Effect of the invention〕

As described above, according to the present invention, when restarting an internal combustion engine, the vapor bubbles flowing into the main well from the horizontal fuel passage can be crushed into small pieces and dispersed at various locations in the circumferential direction, resulting in percolation. Since the internal combustion engine can be reduced, the internal combustion engine can be started reliably in a short time, and restartability can be greatly improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main parts of the carburetor, FIG. 2 is a sectional view taken along ■-■ of FIG. 1, and FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3. 1... Carburetor body, 2... Intake passage, 3...
・Float chamber, 4... Throttle valve, 5... Main well, 7... Main nozzle, 8... Main fuel passage, 9... Main agent, 10...
Lateral fuel passage, 10a... Ceiling surface of the horizontal fuel passage, 15... Slow system fuel passage, 16... Emulsion tube, 17... Small hole, 18... Air bleed, 19... Cone, 19a... Round corner.

Claims (1)

[Claims] (1) Inside the main well, whose lower part communicates with the float chamber via the main jet and also with a fuel passage that extends substantially horizontally, such as a slow system fuel passage, and whose upper part communicates with the main fuel passage to the main nozzle. In a vaporizer in which an emulsion tube is inserted, a downwardly tapered cone is integrally provided at the lower end of the emulsion tube, and the top of the cone is formed into a rounded corner surface with an appropriate radius; An emulsion tube for a carburetor, characterized in that the rounded corner surface is located at a position slightly below the ceiling surface of the horizontal fuel passage.