JPH0810678Y2 - Vaporizer float chamber structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a float chamber structure of a carburetor of an internal combustion engine, and more particularly to a float chamber structure for preventing fuel in the float chamber from leaking from an air vent. .

[Conventional technology]

When the vaporizer is in a relatively high temperature state and a relatively large amount of fuel is supplied into the float chamber, the low boiling point component contained in the supplied fuel abruptly boils, and bubbling of the fuel occurs. That is, air vent spewing occurs.
The occurrence of this bubbling changes a predetermined air-fuel ratio and adversely affects the operating state of the engine.

As a countermeasure against this, a float chamber structure including a primary air vent and a secondary air vent is known.
In this structure, the intake air that has flowed into the float chamber from the primary air vent is exhausted from the secondary air vent to the intake passage again to forcibly ventilate the float chamber and suppress the bubbling of fuel.

However, in the float chamber structure having a simple ventilation function, there is a problem in that the fuel flows into the secondary air vent due to the ripple of the fuel in the state where the liquid level of the fuel fluctuates like the engine mounted on the vehicle. .

Therefore, there has been proposed a structure for preventing fuel leakage from the float chamber in which a partition plate is arranged between the opening end of the secondary air vent into the space of the float chamber and the liquid level in the fuel in the float chamber (Actual No. Sho 56-25050). Issue).

[Problems to be solved by the device]

However, in the structure of the float chamber of the above publication, the liquid level fluctuation of the fuel can be suppressed by the partition plate, but since the partition plate restricts the opening area of the space part in the float chamber, at the time of bubbling (at the time of air vent spewing). The pressure of the flow passage in the float chamber becomes high and the fuel is likely to be discharged from the secondary air vent to the intake passage.

It is an object of the present invention to provide a float chamber structure of a carburetor capable of preventing the fuel from flowing into the secondary air vent when the liquid level changes, while ensuring sufficient ventilation in the float chamber.

[Means for solving the problem]

A float chamber structure of a carburetor according to the present invention for this purpose includes a primary air vent in which a dynamic pressure acts on an intake air flow and a secondary air vent in which a static pressure acts on the intake air flow. In the float chamber structure of the container, the opening of the secondary air vent to the float chamber is arranged in the dent portion that is recessed outward from the inner wall surface of the float chamber, and is an obstacle for suppressing the displacement of the liquid surface of the fuel in the float chamber. The plate is provided only in the inner wall of the float chamber just below the opening of the secondary air vent, and the opening side of the secondary air vent of the baffle plate connects the opening of the primary air vent and the opening of the secondary air vent. A hypotenuse that is substantially parallel to a straight line, and the distance between the hypotenuse and the corner of the dent portion that faces the hypotenuse is determined by the secondary air vent. Consisting of those that is almost the same as the inner diameter of the opening into the float chamber.

[Action]

In the float chamber structure of the carburetor configured as described above, the opening portion of the secondary air vent to the float chamber is arranged in the dent portion which is dented outward from the inner wall surface of the float chamber, and is provided immediately below the opening portion. Since the baffle plate is provided, even if the liquid level of the fuel in the float chamber greatly changes during turning of the vehicle, for example, the fuel does not reach directly below the opening of the secondary air vent. That is, since the opening part escapes to the outside by the recessed part,
Even if the fuel rises along the inner wall surface of the float chamber, it becomes difficult for the fuel to enter the opening and the rise of the fuel is blocked by the baffle plate, so that the fuel is prevented from flowing into the opening of the secondary air vent. It

Further, since the baffle plate may be provided only in the vicinity of the opening of the secondary air vent, the area occupied by the baffle plate with respect to the entire area of the float chamber can be made significantly smaller than that of the conventional structure. Further, since the opening side of the secondary air vent of the baffle plate is a hypotenuse substantially parallel to the straight line connecting the opening of the primary air vent and the opening of the secondary air vent, the opening of the primary air vent of the opening of the secondary air vent. It is possible to increase the directivity for. As a result, the flow of intake air in the float chamber becomes good, and ventilation of the float chamber is sufficiently ensured. Therefore, even if foaming occurs, it is possible to sufficiently suppress the amount of foaming with sufficient ventilation capacity.

〔Example〕

Hereinafter, a preferred embodiment of a float chamber structure of a carburetor according to the present invention will be described with reference to the drawings.

1 to 4 show an embodiment of the present invention, and particularly an example applied to a carburetor of an engine mounted on a vehicle. In the figure, 1 indicates an engine,
The engine 1 is mounted horizontally. That is, the engine 1 is arranged so that the crankshaft is orthogonal to the vehicle traveling direction S. An intake manifold 2 is attached to one side surface of the engine 1, and a carburetor 3 is located above the intake manifold 2.

The vaporizer 3 is a two-barrel type and has a primary bore 4 and a secondary bore 5. The primary bore 4 and the secondary bore 5 are arranged via a partition wall 6. An air chamber 8 connected in parallel with the primary bore via a partition wall 7 is located near the primary bore and the secondary bore 5. Further, a float chamber 10 is located near the air chamber 8 via a partition wall 9.

One of the pipe-shaped primary air vents 11 that supplies intake air to the float chamber 10 is opened in the air chamber 8. The other opening 11a of this primary air vent 11
Is located near the corner 10a of the float chamber 10 having a rectangular cross section. The primary air vent 11 opens into the air chamber 8 so that dynamic pressure acts on the intake air flow flowing through the air chamber 8.

One of the pipe-shaped secondary air vents 12 that discharges the intake air that has flowed into the float chamber 10 is open to the secondary bore 5. The other side of the secondary air vent 12 opens in the vicinity of a corner portion of the float chamber 10 that faces the corner portion 10a. The opening 12a of the secondary air vent 12 that opens toward the float chamber 10 side is the inner wall surface 1 of the float chamber 10.
It is located in the indented portion 10g that is recessed outward from 0c.
In this embodiment, the portion of the inner peripheral surface of the opening 12a closest to the float chamber 10 is the inner wall surface 10c on the long side of the float chamber 10.
The inner wall surface 10d on the short side of the float chamber 10 and a part of the inner peripheral surface of the opening 12a substantially coincide with each other.

Opening 12a of the secondary air vent 12 of the float chamber 10
A concave portion 10e is formed on the inner wall surface facing the inner wall surface 10c on the long side where the is arranged.

A baffle plate 13 that suppresses the displacement of the liquid level L of the fuel F in the float chamber 10 is provided on the inner wall surface 10d on the short side of the float chamber 10 adjacent to the opening 12a of the secondary air vent 12. The baffle plate 13 is larger than the maximum displacement height of the float 14,
Located on top. The baffle plate 13 has a substantially trapezoidal planar shape. The secondary air vents 12 of the baffle plate 13 and the oblique side 13a on the side of the opening 12a are the openings of the primary air vent 11.
It is substantially parallel to a straight line A connecting 11a and the opening 12a of the secondary air vent 12. Hypotenuse 13a of baffle plate 13
Of the float chamber 10 facing the
Are formed in an arc shape. Corner 10f and baffle 13
The distance W from the hypotenuse 13a is substantially the same as the inner diameter of the opening 12a. That is, by directing the opening 12a of the secondary air vent 12 toward the opening 11a of the primary air vent 11, the float chamber is removed from the primary air vent 11.
The intake air that has flowed into the inside 10 smoothly flows into the opening 12a of the secondary air vent 12.

Thus, in this embodiment, the baffle plate 13 and the corner portion 10f are
The distance W between the opening 12a and the inner diameter of the opening 12a is substantially the same as the inner diameter of the opening 12a.
It can be set in the double range. Furthermore, the hypotenuse 13 of the baffle 13
Although a is almost parallel to the straight line A, the inclination angle θ of this side 13a is such that the inner wall surface 10d on the short side where the baffle plate 13 is provided is
Can be set in the range of 10 to 80 °.

Next, the operation of the float chamber structure of the vaporizer will be described.

When the vehicle is traveling straight, the carburetor 3 is kept horizontal, and the liquid level L of the fuel F in the float chamber 10 is shown in FIGS.
As shown by the chain double-dashed line in the figure, the normal oil level position is maintained. If the vehicle makes a sharp turn from this state, a large centrifugal force acts on the fuel F in the float chamber 10 toward the outside of the turn, and the carburetor 3 tilts, causing a large change in the liquid level of the fuel F. Therefore, the fuel may flow into the opening 12a of the secondary air vent 12 due to the fluctuation of the liquid level of the fuel F, but since the baffle plate 13 is adjacent immediately below the opening 12a, the baffle plate 13 is adjacent to the opening 12a. As shown by the solid line in FIG. 4, the baffle plate 13 prevents the liquid level of the fuel F from rising, and the fuel does not reach directly below the opening 12a. That is, since the opening 12a of the secondary air vent 12 is escaped from the inner wall surface 10c of the float chamber 10 by the recessed portion 10g, even if the fuel F rises along the inner wall surface 10c, 10d of the float chamber 10, this portion The fuel rise in the is blocked by the baffle 13 and the fuel secondary air vent
The flow of 12 into the opening 12a is prevented. Also, baffle 13
Area is significantly smaller than the cross-sectional area of the float chamber 10, so the flow path of the intake air is almost not throttled, and even when bubbling (air vent spewing) occurs, the pressure of the flow path rises as in the conventional structure. There is also nothing to do.
Therefore, also in this case, the fuel in the float chamber 10 is prevented from flowing into the opening 12a of the secondary air vent 12. Furthermore, since the opening 11a of the primary air vent 11 and the opening 12a of the secondary air vent 12 are located on a substantially straight line, the flow of intake air in the float chamber 10 is good, and the ventilation of the float chamber 10 is sufficiently ensured. .

[Effect of device]

According to the float chamber structure of the carburetor according to the present invention, the opening of the secondary air vent to the float chamber is arranged at the recessed portion that is recessed outward from the inner wall surface of the float chamber, and the liquid level of the fuel in the float chamber is The baffle that suppresses displacement is provided only on the inner wall surface of the float chamber just below the opening of the secondary air vent, so even if the fuel level in the float chamber changes significantly due to sudden turning of the vehicle, the secondary air vent It is possible to prevent the fuel from flowing into the opening of the.

In addition, the opening side of the secondary air vent of the baffle plate,
Since the hypotenuse is substantially parallel to the straight line connecting the opening of the primary air vent and the opening of the secondary air vent, the directivity of the opening of the secondary air vent to the opening of the primary air vent can be enhanced. Therefore, the intake air that has flowed into the float chamber from the primary air vent can be positively flowed toward the secondary air vent, and even if foaming occurs, the amount of the generated air can be sufficiently suppressed with sufficient ventilation capacity.

In this way, it is possible to prevent the fuel from flowing into the secondary air vent due to the fluctuation of the liquid level and the bubbling of the fuel in the float chamber, avoid the engine misfire due to the excessive concentration of the air-fuel mixture, and prevent the engine stall from occurring. it can.

In addition, since an almost proper air-fuel mixture can be obtained under any operating condition, deterioration of drivability due to abnormal combustion and overheating of the catalyst can be prevented.

[Brief description of drawings]

1 is a sectional view of a float chamber structure of a vaporizer according to an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of FIG. 1, FIG. 3 is a sectional view of FIG. 2, and FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3. 1 …… Engine 3 …… Vaporizer 10 …… Float chamber 10c …… Inner wall surface 10g …… Indentation 11 …… Primary air vent 12 …… Secondary air vent 12a …… Opening 13 …… Baffle plate A …… Straight line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-49-61526 (JP, A) Actually open Sho-56-25050 (JP, U) Actual-open Sho-59-76743 (JP, U) Actual-open Sho-63- 75554 (JP, U) Actual development Sho 59-49751 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A float chamber structure of a carburetor, comprising: a primary air vent that exerts a dynamic pressure on an intake air flow; and a secondary air vent that exerts a static pressure on the intake air flow. The baffle plate for arranging the opening portion to the float chamber in the dent portion that is dented outward from the inner wall surface of the float chamber, and suppressing the displacement of the liquid level of the fuel in the float chamber is the secondary wall of the inner wall of the float chamber. Provided only in the vicinity of just below the opening of the air vent, the opening side of the secondary air vent of the baffle plate is a hypotenuse substantially parallel to a straight line connecting the opening of the primary air vent and the opening of the secondary air vent, The distance between the hypotenuse and the corner of the recess facing the hypotenuse is approximately the same as the inner diameter of the opening of the secondary air vent to the float chamber. Float chamber structure of the carburetor, characterized in that the.