JPS59128959A - Carburetor - Google Patents

Abstract

PURPOSE:To unify the density of the air-fuel mixture during idling by providing a fuel injection hole in a direction different from the axis of an idle nozzle. CONSTITUTION:An idle nozzle is closed at its tip 10 and is bored with a fuel injection hole 9 on the side wall near the tip. Thereby, the fuel is blown in at an angle near a right angle in relation to an arrow direction K of the air stream, and a local eddy current is generated simultaneously with the atomization, thereby the uniform air-fuel mixture can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a carburetor for an internal combustion engine, and more particularly to a carburetor improved so as to be able to generate a uniform air-fuel mixture during idling.

[Prior art]

Figure 1 shows the entire vertical cross section of an example of a conventionally commonly used carburetor, and the right half P of the figure shows the primary for low load,
The left half is the secondary one for use under high loads. 1 is the carburetor body, 2 is the intake cylinder, 3 is the fuel passage for low speeds, 4 is the bypass chamber, 5 is the idle nozzle, 6 is the opening through which the bypass chamber communicates with the intake cylinder, 7 is the throttle valve, 111d'F - York pulp.

Bubbles sucked in from the air bleed 8 are mixed with the fuel supplied from the low speed fuel passage 3Fi and the float chamber (not shown), and the mixture is guided to the bypass chamber 4, and then passed through the bypass opening 6 and the idle nozzle 5 to the intake cylinder 2. Make it squirt inside. In the conventional low-speed fuel system as described above, a large amount of bubbles are generated in the bypass chamber 4 as the ambient temperature of the carburetor or the engine temperature increases, and the continuous flow of fuel in the carburetor is interrupted. Due to the air bubbles that adhere to the inner surface of the bypass chamber 4, which often become obstructive, the air-fuel ratio of the fuel sucked into each cylinder of the engine becomes non-uniform.

If the air-fuel ratio becomes uneven, the best combustion conditions cannot be maintained, resulting in poor exhaust gas composition and exhaust gas color.

FIG. 2 shows an engine E mounted on a car body 12 and a carburetor C'.
It is a diagram schematically depicting the state in which the FT is equipped. F indicates the float, PVi indicates the primary, and S indicates the secondary IJ', and the arrow G indicates the method of movement of the vehicle body 12. Engine E is shown in Figure 2 (A-1).

(A-2) when the vehicle is mounted parallel to the direction of travel, and CB-1) and (B-2) in the same figure when it is mounted perpendicular to the direction of travel. Also, carburetor C for this engine E? For the mounting position, see Figure 2 (A-
1) There are also cases where it is installed on the side of the engine, as in
Although it may be installed above the engine as shown in the same figure (B-2), in any of these cases, the primary P and secondary S are installed at right angles to the center line of the engine, and the engine The carburetor C is designed to act equally on each cylinder of the engine E.

Even if consideration is given to the mounting position and posture of the carburetor C as described above, the density distribution of the air-fuel mixture formed by the carburetor C in the intake pipe is not uniform. (not shown) and the air-fuel ratio of the mixture supplied to each cylinder varies. Particularly when the engine is idle, fuel is mainly supplied through the idle nozzle 5'f.
If the fuel sprayed from the VC is not uniformly dispersed in the intake air flow (that is, until it reaches the branch point of the manifold), the above-mentioned non-uniform air-fuel ratio among the cylinders will occur.

[Object of the invention]

The present invention has been made in view of the above-mentioned circumstances, and provides a carburetor that can rapidly disperse fuel sprayed from an idle nozzle into intake air when the engine is idle to form a mixed air flow with a uniform concentration. This is what I am trying to do.

It is naturally expected that the air-fuel ratio of the air-fuel mixture injected into the cylinders will be equal, and it is possible to control the air-fuel ratio of the air-fuel mixture to maintain good combustion conditions in each cylinder. , startability, low-speed stability, fuel consumption during idling, and exhaust emissions can be improved.

[Summary of the invention]

In the conventional carburetor shown in FIG. 1, the following may be the cause of the non-uniformity of the air-fuel mixture during idling.

``When idling, the throttle valve 7 is slightly open, and air flows in the direction of arrow J. Even if fuel is injected into the airflow in the direction of this arrow in the direction of the lack of fuel, which is the same direction as this, a vortex will be created, resulting in an air-fuel mixture that is close to a laminar flow. From the above considerations, injecting fuel at an angle close to perpendicular to the direction arrow K of the air flow,
It is thought that a homogeneous air-fuel mixture can be obtained by generating a local eddy current at the same time as koji formation. The present inventors conducted experiments based on the above study results, confirmed that a uniform air-fuel mixture could be obtained, and came up with the present invention.

In order to generate a homogeneous mixture based on the above principle,
The carburetor of the present invention closes the tip of a tubular idle nozzle provided downstream of the throttle valve in order to stabilize low-speed rotation, and fuel is injected near the tip of the tube in a direction different from the axis of the idle nozzle. It is characterized by having holes.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to FIG. This embodiment is an improved version of the conventional carburetor described above (FIG. 1) by applying the present invention, and differs from the conventional device in the configuration of the idle nozzle 5.

FIG. 3 is an enlarged depiction of the vicinity of the idle nozzle 5 in FIG. 1.

The idle nozzle of this embodiment has a closed tip 101c and a fuel injection hole 9 in the side wall near the tip.

When applying the present invention 1, the tip 10 of the idle nozzle 5 may not be completely closed and a pore may be left. In the present invention, closing the opening at the tip of the idle nozzle 5 does not necessarily mean completely closing it, but also includes partially closing it while leaving a pore. In short, by providing a jet hole at an angle nearly perpendicular to the intake air flow arrow K, like the jet hole 9 in this example, the mixing state of air and fuel is significantly improved.

In this embodiment, an ejection hole 91 is formed in the vicinity of the tip of the idle nozzle 5 in a direction approximately perpendicular to the axis of the idle nozzle, and this ejection hole 9 is aligned with the axis of the intake cylinder 2. Good results as described below were obtained by assembling them at almost right angles. When carrying out the present invention, the number of ejection holes is 90,
It is desirable to set the direction and dimensions so as to obtain the best results in terms of real numbers. The best shape dimensions vary slightly for each engine type.

FIG. 4 is a chart showing the air-fuel ratio of the intake air-fuel mixture of each cylinder during idling for a four-cylinder engine. When the conventional carburetor shown in Fig. 1 is used, the air-fuel ratio varies between 11 and 17, as shown by the broken line, but when the carburetor of the embodiment shown in Fig. 3 is used. is 13 to 15 as shown in the solid line
are within the range.

FIG. 5 is a chart showing temporal changes in the hydrocarbon (HC) content of exhaust gas water. In the case where the conventional vaporizer is used, the temporal change in HC#[ is large, but when the vaporizer sound of this example is used, the absolute value of the HC concentration decreases noticeably and the temporal change almost disappears. did. This experimental result indicates that a good combustion state can be maintained stably in each cylinder.

〔Effect of the invention〕

As explained above, in a carburetor for a multi-cylinder engine, the opening at the tip of the tubular idle nozzle provided downstream of the throttle valve is closed in order to completely stabilize low-speed operation, and the opening of the tubular idle nozzle is closed. By providing a fuel injection hole near the tip of the idle nozzle in a direction different from the axis of the idle nozzle, the concentration of the air-fuel mixture in the idle nozzle is made uniform, and the combustion condition in each cylinder is improved, making it possible to start the engine. This not only improves performance and low-speed stability, but also improves fuel efficiency and exhaust color during idling.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional carburetor, FIG. 2 is a schematic diagram for explaining the mounting state of an engine and the carburetor, and FIG. 3 is a sectional view of an embodiment of the present invention. FIGS. 4 and 5 are charts showing the effects of the present invention. DESCRIPTION OF SYMBOLS 1... Carburetor main body, 2... Intake cylinder, 3... Fuel passage for low speed, 4... Bypass chamber, 5... Idle nozzle, 6... Opening of bypass chamber, 7 ... Throttle valve, 8... Slow air bleed, 9... Fuel injection hole, 10... Tip of idle nozzle, 11.
...Chalk pulp, 12...Car body. Agent Patent Attorney Masami Akimoto 1st day N 20th (A-1) 20th (A-2) 7th Ward (I3-2)
Tougincho

Claims (1)

[Claims] 1. In a carburetor for a multi-cylinder engine, in order to stabilize low-speed operation, close the opening at the tip of the tubular idle nozzle installed downstream of the throttle valve, and close the opening at the tip of the idle nozzle with a careful seal near the tip of the idle nozzle. A carburetor characterized in that fuel injection holes are provided in different directions.