JPS6118214Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of the main nozzle of a carburetor, and particularly includes a main nozzle having a structure suitable for preventing droplets from dropping when fuel starts coming out from the main nozzle and promoting atomization. Regarding vaporizers.

Fig. 1 shows a conventional embodiment as described in Japanese Patent Application Laid-Open No. 54-58141. The fuel supplied from the carburetor 1 to the engine is calculated by the main jet 7, and a gas-liquid mixed flow is formed by the main air bleed 5 and the mixing tube 6, and the small ventilator 3 is used.
The water is sprayed from the main nozzle 4 which opens to the
As is well known, fuel is drawn out by the negative pressure _Pv generated in the small venturi 3 according to the intake air volume. Since this _Pv is small when the fuel starts to come out of the main nozzle 4, the fuel is ejected intermittently, and the vortex generated at the bottom of the main nozzle 4 induces the adhesion of fuel as shown in the figure. The adhered fuel runs from the bottom of the main nozzle 4 along the wall of the small venturi 3, stays on the skirt 9, and then becomes large droplets and hits the throttle valve 2. These fuel droplets that drip onto the throttle valve 2 are sucked in almost as they are downstream of the throttle valve 2, so that when the fuel drips during partial load operation (e.g. _Pv /L40Km/h) at the start of main discharge as shown in Figure 5, a spike (temporary rich phenomenon) of CO is generated as shown by the solid line A.

2 1, there is a fluctuation ΔT _a in the shaft torque as shown by the solid line.

There is a problem.

The above 1 makes it difficult to comply with exhaust regulations and is also unfavorable in terms of fuel economy. 2 also leads to deterioration of drivability such as so-called surging. Figure 4 shows the distribution performance in a 4-cylinder engine, and the difference between the 3 cylinders with the largest excess air ratio λ and the 4 cylinders with the smallest excess air ratio λ is large, Δλ _a , which is also a cause of deterioration of engine stability. It was becoming.

The purpose of this invention is to provide a main nozzle with a structure suitable for preventing fuel from dripping at the beginning of main discharge, promoting atomization, and improving A/F stability, fuel economy, and drivability. It is about providing.

The present invention has a structure in which grooves are provided on the inner wall of the small bench lily 3 to introduce dynamic pressure to the outer periphery of the main nozzle 4, as shown in Fig. 2, to prevent fuel from dripping and promote atomization. It is something.

An embodiment of the present invention will be described below with reference to FIG. A groove 10 is provided in the inner wall of the small bench lily 3 in the intake direction, and an annular gap 11 connected to the groove 10 is formed between the main nozzle 4 and the small bench lily 3. When the intake air amount reaches the amount at which the fuel is jetted from the main nozzle 4, dynamic pressure is applied to the upper part of the main nozzle 4, and the lower part becomes a static pressure state as eddies occur. Therefore, since the air flow actively moves from the dynamic pressure (positive pressure) side to the static pressure (negative pressure) side, the air flow velocity in the annular gap 11 increases. Therefore, the fuel ejected from the main nozzle 4 hardly adheres to the lower part of the main nozzle 4 due to the presence of the air flow as shown by the arrow in the figure. Furthermore, since the airflow within the small bench lily 3 promotes atomization of the fuel, the droplets that occur in the prior art do not occur. The dashed-dotted line in Figure 5 shows the result of using the main nozzle structure according to the present invention; CO is stable as shown in _B , and the amount of fluctuation in shaft torque is reduced to about 1/8 of that of the conventional technology. There is. In addition, the distribution performance between the cylinders is a difference of Δλ _b as shown by the dashed line in Figure 4, which is approximately 1/5 of Δλ _a .
has decreased to.

FIG. 3 shows a modification of the invention. The wall thickness of the main nozzle 4 is made thinner toward the spout, and the surface tension at the tip of the main nozzle 4 is increased to prevent the sagging phenomenon of the nozzle alone.
In combination with the airflow passing through the annular gap 11, the performance can be further improved.

Furthermore, according to the present invention, even if the amount of intake air increases, the air flowing through the groove 10 always flows in the direction of the arrow.
Phenomena such as plateauing at high speed and fuel spraying to the opposite wall of the main nozzle 4 do not occur.

According to the present invention, by introducing dynamic pressure to the outer periphery of the main nozzle 4, the fuel does not travel along the lower part of the main nozzle 4 and adhere to the small bench lily 3, and atomization is promoted by the air flowing through the bench lily. We were able to significantly improve A/F stability, fuel economy, and drivability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a carburetor including a main nozzle according to the prior art, FIGS. 2 and 3 are explanatory diagrams of a carburetor including a main nozzle according to the present invention, FIG. 4 is a distribution performance diagram in a four-cylinder engine, and FIG. Figure 5 is a chart of CO and shaft torque T. 1... Carburetor, 2... Throttle valve, 3... Small bench lily, 4... Main nozzle, 5... Main air bleed, 6... Mixing pipe, 7... Main jet, 8... Float, 9... Skirt, 10...
...Groove, 11...Annular gap.

Claims (1)

[Scope of utility model registration request] In a fuel injection main nozzle that protrudes from the inner wall of the bench lily toward the intake passage, the bench lily includes a groove that deflects the airflow flowing along the inner wall of the bench lily toward the tip of the main nozzle at the lower part of the main nozzle. A vaporizer characterized by being engraved on the inner wall of.