JP2588891Y2 - Multi-injection nozzle for vaporizer - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a multi-injection nozzle of a carburetor for a two-cycle engine having a plurality of fuel injection holes on an outer peripheral wall.

[0002]

2. Description of the Related Art As a multi-injection nozzle of this type applied to a vaporizer, for example, a technique disclosed in Japanese Utility Model Laid-Open No. 2-11063 is known. In this prior art, as shown in FIG. 3 , a pipe-shaped injection nozzle 13 is fixed to the tip of a piston 11 that changes the internal cross section of the intake passage 10, and the injection nozzle 13 is inserted into the needle jet 12. The fuel nozzle is slidably fitted, and a number of fuel injection holes 14 are formed in the outer peripheral wall surface of the injection nozzle 13. According to this, the fuel is injected from the float chamber (not shown) through the needle jet 12 into the intake passage 10 through the injection nozzle 13, so that the dispersion of the fuel is averaged, and the atomization state is improved. That is.

[0003] As another prior art, for example, a technique disclosed in Japanese Utility Model Publication No. 47-2973 is known. According to this technique, a large number of small holes are formed at the tip of a piston that varies the internal cross section of the intake passage in the same manner as described above. A pipe-shaped injection nozzle having a small hole is attached, and the small hole can be set in an arbitrary direction with respect to the air flow. Thereby, the same effect as described above can be obtained.

[0004] The structure of these injection nozzles is significantly different from the conventional ones in that the fuel is injected from a number of small holes provided on the outer peripheral wall surface of the injection nozzle. It is determined by the number or the arrangement of the holes.

[0005]

However, in these prior arts, the specific arrangement position or specific direction of the fuel injection hole, which is considered to be one of the factors that have the greatest influence on fuel adjustment, is not at all. Although it is not disclosed, merely using a configuration in which a large number of small holes are provided on the outer peripheral wall surface of the injection nozzle or a configuration in which fuel is ejected from these small holes in an appropriate direction is not particularly sufficient for engine intake in a two-cycle engine. Considering the influence of the pulsation, it is difficult to expect a better effect in a carburetor that requires atomization improvement and high-speed response of the ejected fuel by dispersing the ejected fuel.

That is, as shown in FIG. 4 , when the fuel ejection holes 14 are arranged on the upstream side of the center line c ₁ -c ₁ of the nozzle cross section in a direction substantially orthogonal to the airflow flowing through the intake passage 10, the fuel is ejected. The spread of the fuel flow increases and the tendency to adhere to the surrounding walls increases. Conversely, as shown in FIG. 5 , even when the angle Θ is not so large even on the downstream side of the center line c ₁ -c ₁ of the nozzle cross section (for example, 0 degree ≦ Θ <4
5 degrees), the more fuel is injected into the engine combustion chamber due to the pulsation of the engine intake fuel as the throttle opening increases, the more time lag (time shift) occurs when the fuel is transmitted to the engine combustion chamber. Engine rotation becomes difficult.

This is because, in the case of a two-cycle engine, in particular, since there is one suction stroke for every two strokes of the piston, even a slight time lag affects combustion and cannot be ignored. For this reason, it was necessary to select the arrangement position of the fuel ejection holes 14 at an appropriate position on the nozzle cross section.

The present invention has been made to solve such a problem, and an object of the present invention is to reduce the influence of the engine intake pulsation in a two-stroke engine, and reduce the fuel injected according to the throttle opening. It is an object of the present invention to provide a multi-injection nozzle of a carburetor which can be taken into an engine combustion chamber.

[0009]

In order to achieve the above object, the present invention is directed to a piston fixed to a piston which changes the internal cross section of an intake passage, has a plurality of fuel ejection holes along a longitudinal direction, and has a fuel flow passage inside. A multi-injection nozzle of a carburetor, which has a closed cylindrical shape formed with and is slidably fitted into a needle jet and capable of ejecting fuel in a float chamber from the fuel ejection hole into an intake passage. ,
The fuel flows through the intake passage in the nozzle cross section through the fuel outlet.
Symmetrically with respect to the center line in the direction along the airflow,
In addition, the fuel outlets are
Downstream from the center line in a direction approximately perpendicular to the airflow flowing through the road
It is characterized by being arranged at an angle Θ (45 degrees ≦ Θ <90 degrees) .

[0010]

According to the present invention, according to the present invention, fuel injected from the fuel injection hole is supplied to the engine combustion chamber while being concentrated at the central portion of the intake passage where airflow is fast. Part of the fuel is blown back to the side opposite to the airflow direction under the influence of the engine intake pulsation.

However, the amount of fuel that is blown back can be considerably suppressed by arranging the fuel ejection holes in a specific angle range downstream of the airflow, and the fuel that is blown back is dispersed near the cylinder in the intake passage. Exists and is captured and used immediately before the next explosion process.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the same or corresponding members are denoted by the same reference symbols throughout the drawings. FIG. 1 is a longitudinal sectional view showing a case where the present invention is applied to a sliding valve carburetor. In the figure, a closed cylindrical multi-injection nozzle 13 is fixed at the center of the tip of a piston 11 that varies the cross section in the intake passage 10. Immediately below the multi-injection nozzle 13, a carburetor main body 17 side is provided. A needle jet 12 is formed. On the outer peripheral wall surface of the multi-injection nozzle 13, a plurality of small fuel injection holes
Are formed, and a fuel flow path 15 communicating with the needle jet 12 is formed inside (see FIG. 2 ).

The multi-injection nozzle 13 is slidably fitted into the needle jet 12, so that the fuel in the float chamber 16 flows through the flow path 15 by the negative pressure due to the vertical movement of the piston 11. The gas is ejected from the ejection holes 14 into the intake passage 10. At this time, piston 1
The number of fuel ejection holes 14 exposed in the intake passage 10 changes according to the up and down movement of 1, and the amount of fuel ejected into the intake passage 10 changes accordingly.

Here, in the present invention, the fuel injection
The holes 14, 14 are provided in the air flowing through the intake passage 10 as shown in FIG.
With respect to the center line c ₂ -c ₂ in the direction of the nozzle cross-section along the flow
The fuel injection holes 14, 14 are provided substantially symmetrically, and
Substantially perpendicular to the airflow flowing through the intake passage in the cross section of the nozzle
Angle from the center line in the downstream direction to the downstream side (45 degrees ≦ Θ <90
Degree). Here symmetrical is meant that with respect to the center line c ₂ -c ₂ and the angle Θ of the right ejection hole 14 and the left ejection holes 14 are identical in FIG.

That is, as shown in FIG. 2, a center line c ₁ -c ₁ (angle Θ = 0) in a direction substantially perpendicular to the airflow flowing through the intake passage 10 in the cross section of the nozzle in the fuel injection hole 14.
From the position 45 degrees downstream from the angle (degrees), the angle 下流 is less than 90 degrees , ie, 45 degrees ≦ Θ <90 degrees . As described above, by providing the fuel ejection holes 14 on the downstream side of the specific range of the airflow, the atomized fuel flow is concentrated and supplied from the fuel ejection holes 14 to the central portion of the intake passage 10 where the airflow is fast. On the other hand, fuel injection holes 14
A part of the fuel ejected from the engine is blown back to the side opposite to the airflow direction under the influence of the engine intake pulsation. But,
The amount of fuel blown back at this time is considerably suppressed by arranging the fuel ejection hole 14 at a specific position on the downstream side of the airflow, and the blown back fuel is dispersed and present near the intake manifold in the intake passage 10, This is taken into the cylinder and used effectively before the next explosion process. Also, the fuel outlet 14 is located downstream of a specific range of the airflow.
Atomized fuel that has been jetted
Are dispersed in the intake passage 10 in a nearly uniform state.
It becomes possible.

Here, if the fuel ejection hole 14 is set at an angle of 45 degrees or less from the center line c ₁ -c ₁ of the nozzle cross section (0 degree ≦ Θ)
<45 degrees), the higher the opening of the throttle valve, the more the injected fuel is blown back to the side opposite to the airflow direction under the influence of the engine intake pulsation, and the fuel is thereby burned by the cylinder. A time lag (time shift) occurs before reaching the room. And this time lag is 4 times with one suction stroke for every 4 strokes of the piston.
This is not a problem in a cycle engine, but is particularly a problem in a two-cycle engine having one suction stroke for every two strokes of the piston because there is not enough waiting time. From this viewpoint, the fuel ejection hole 14 is set to 0 degree ≦
Setting Θ <45 degrees is impractical and has no room for adoption.

In the above embodiment, the case where the present invention is applied to a sliding valve type carburetor has been described, but it is needless to say that the present invention can also be applied to a negative pressure type carburetor.

[0018]

As described above, the present invention does not simply set the fuel ejection hole in an unspecified direction with respect to the air flow as in the prior art, but in the direction substantially orthogonal to the air flow in the cross section of the nozzle. Angle Θ (4
5 ° ≦ Θ <90 ° ), the fuel flow spouted from the fuel outlet becomes narrower and concentrates on the fast air flow in the center of the intake passage and adheres to the wall around the intake passage. As a result, the wall flow can be minimized. At this time, part of the fuel ejected from the fuel ejection hole is blown back to the opposite side to the airflow direction under the influence of the engine intake pulsation, but according to the present invention, the fuel ejection hole is moved to a specific range on the downstream side of the airflow. With this arrangement, the amount of fuel that is blown back is considerably reduced, and the fuel that is blown back is dispersed near the intake manifold in the intake passage, which is used effectively in the next explosion process, so that a stable engine Rotation can be secured.

Further, since the fuel ejection holes are provided substantially symmetrically with respect to the center line of the cross section of the nozzle, the ejected fuel is evenly distributed on both left and right sides of the nozzle in the intake passage as a center, and the fuel mist is formed. The state of oxidation is significantly improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view when the present invention is applied to a sliding valve type carburetor.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic longitudinal sectional view of a conventional sliding valve carburetor.

FIG. 4 is a cross-sectional view showing one example along the line BB in FIG . 3 ;

FIG. 5 is a sectional view showing another example along the line BB in FIG . 3 ;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Intake passage 11 Piston 12 Needle jet 13 Multi-injection nozzle 14 Fuel ejection hole 15 Flow path 16 Float chamber 17 Main body of carburetor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02M 19/03 F02M 7/17 F02M 9/03-9/06

Claims (1)

(57) [Scope of request for utility model registration] 1. A closed cylindrical shape which is fixed to a piston which varies the internal cross section of an intake passage, has a plurality of fuel ejection holes along a longitudinal direction, and has a fuel flow passage formed inside,
And the multi-jet nozzle of the vaporizer which enables ejected from slidably fitted has been the fuel injection holes of the fuel in the float chamber to the intake passage in the needle jet, intake air in the nozzle cross section of the fuel ejection hole Flow through the passage
Symmetrically with respect to the center line in the direction along the airflow,
In addition, the fuel outlets are
Downstream from the center line in a direction approximately perpendicular to the airflow flowing through the road
A multi-injection nozzle for a carburetor, wherein the nozzle is arranged at an angle Θ (45 degrees ≦ Θ <90 degrees) .