JPH0143495Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a two-stage carburetor generally used in automobile engines.

[Conventional technology]

In automobile engines, it is common to use a two-stage carburetor to achieve both fuel atomization and engine output performance. And FF of A in Figure 2
Two-stage carburetor 20 in the FR type car C ₁ and the FR type car C ₂ (in both cases, the symbol E indicates the engine)
To explain this with reference to an explanatory diagram of the arrangement, the first-stage carburetor P and the second-stage carburetor S are arranged parallel to the swinging surface L of the float 21, and air vents 22 and 23 are provided respectively. In addition, in order to improve ventilation in the float chamber 24 and prevent percolation and spills at high temperatures, the first-stage air vent 22 is of a dynamic pressure type, and the second-stage air vent 23 is of a static pressure type. In many cases, a part of the intake air of P is blown through the float chamber 24 into the intake passage of the second-stage side carburetor S. As can be seen from the vertical cross-sectional view of the conventional product in Fig. 3, the float pin 25 and float valve 26 of the float 21 are now installed in the second-stage side carburetor S due to design considerations such as the arrangement of the accelerator pump. Therefore, fuel is supplied to the float chamber 24 from the second stage side carburetor S side.

However, when looking at automobiles equipped with such a carburetor, when the FF automobile C ₁ (D indicates the direction of travel) in Fig. 2A suddenly decelerates, the float chamber 24 as shown in Fig. 3 The oil level of float pin 25
side, that is, the second stage side carburetor S side is higher. As the buoyancy of the float 21 decreases due to this inclination, the float valve 26 opens, allowing excess fuel to flow into the float chamber 24 and raise the entire oil level. It begins to be released into the intake tract. This is because the oil level approaches the opening 23a of the second-stage air vent 23 located near the float pin 25, making it easy for high-concentration gasoline vapor to flow into the opening 23a of the second-stage air vent 23. It is thought that this is because a large amount of gasoline vapor is entrained when the gas flows from the first-stage air vent 22 through the float chamber 24 and from the second-stage air vent 23 to the intake passage of the second-stage carburetor S.

Furthermore, even when the FR vehicle C ₂ shown in FIG. 2B turns in the direction of arrow L, the same phenomenon as described above occurs because the oil level is highly tilted toward the float pin 25 as shown in FIG. 3. In this way, when the FF car C ₁ suddenly decelerates or the FR car C ₂ turns, gasoline vapor is released into the intake passage of the second-stage carburetor S, and these operating conditions last for a long time. If this continues, the entire inclined oil level will rise further and fuel will enter the second stage side air vent 23, and the mixture will become too rich due to these gasoline vapors and the fuel itself, deteriorating engine drivability. It may even lead to an outage.

[Problem that the invention attempts to solve]

In the present invention, the first-stage carburetor and the second-stage carburetor are arranged parallel to the swinging surface of the float, the float pin is provided toward the second-stage carburetor, and there is an opening in the float chamber. In a two-stage vaporizer where the first-stage air vent is a dynamic pressure type and the second-stage air vent is a static pressure type,
The purpose of this is to solve the problem that when the oil level in the float chamber is inclined so that the float pin side is higher, gasoline vapor and fuel flow into the second stage air vent and tend to make the air-fuel mixture too rich.

[Means for solving problems]

In order to solve the above problems of the two-stage vaporizer having the above structure, the present invention provides the opening of the second-stage air vent to the float chamber closer to the first-stage vaporizer than the center of the float chamber.

〔Example〕

Embodiments of the present invention will be described based on the drawings. 1st
The figure is a longitudinal sectional view of a two-stage carburetor in which the first-stage carburetor P and the second-stage carburetor S are arranged parallel to the swinging surface of the float, where 1P is the intake path of the first-stage carburetor P, and 1S 2 is an intake passage of the second-stage carburetor S, 2 is a float chamber, 3 is a float pin, 4 is a float, 5 is a float valve, 6 is a first-stage air vent, and 7 is a second-stage air vent.

The second-stage air vent 7 is formed to extend laterally toward the first-stage carburetor P inside the carburetor main body 8, and the opening 7a to the float chamber 2 is positioned closer to the first-stage carburetor P than the center of the float chamber 2. It is provided close to the opening 6a of the air vent 6 on the side, that is, the first stage side, to the float chamber 2.

Therefore, when the fuel in the float chamber 4 is tilted so that the float pin 3 side becomes higher due to sudden deceleration operation or turning operation, the oil level moves away from the opening 7a of the second stage side air vent 7 than the horizontal specified oil level, This not only prevents gasoline vapor from being released into the second-stage intake passage _1S , but also prevents fuel from being released into the second-stage intake passage 1S even if such operating conditions continue for a long time and the entire inclined oil level rises significantly. It won't go into air vent 7.

In the above embodiment, the second-stage air vent 7 was formed by drilling inside the carburetor main body 8 to form an extension, but a pipe was connected to the opening on the float chamber side of the conventional second-stage air vent, and the opposite end was connected to the opening on the float chamber side. It may be formed by extending the air vent toward the first-stage vaporizer side and opening near the opening of the first-stage air vent.

[Effect of idea]

As described above, in the present invention, the opening of the second-stage air vent to the float chamber is formed closer to the first-stage carburetor than the center of the float chamber. Even if the valve opens and the entire inclined oil level rises significantly, the gasoline vapor in the float chamber and the fuel itself are effectively prevented from being released from the second-stage air vent. This eliminates deterioration in engine drivability and engine stoppage due to excessively rich air-fuel mixture due to fuel discharge.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of an embodiment of the present invention, Figure 2 is an explanatory diagram of the arrangement of a two-stage carburetor, and A is a front-wheel drive vehicle.
Fig. 3, which is an explanatory diagram of the arrangement in an FR automobile, is a longitudinal cross-sectional view of a conventional product. P...First stage side carburetor, S...Second stage side carburetor, 2
...Float chamber, 3...Float pin, 4...Float, 6...
...1st stage side air vent, 7...2nd stage side air vent,
6a, 7a...opening.

Claims (1)

[Scope of utility model registration request] The first-stage carburetor and the second-stage carburetor are arranged parallel to the swinging surface of the float, the float pin is provided toward the second-stage carburetor, and the first-stage air vent opens into the float chamber. In a two-stage vaporizer in which the second-stage air vent is of a dynamic pressure type and the second-stage air vent is of a static pressure type, the opening of the second-stage air vent to the float chamber is provided closer to the first-stage vaporizer than the center of the float chamber. Features a two-stage vaporizer.