JP2578472Y2 - 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. 7, 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. 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. 8, for example, when the fuel ejection holes 14 are arranged upstream of the center line c ₁ -c _{1 of the} cross section of the nozzle in a direction substantially orthogonal to the airflow flowing through the intake passage 10, The spread of the flowing fuel flow increases, and the fuel flow tends to adhere to the surrounding walls. Conversely, as shown in FIG. 9, even if the angle Θ is not so large even if it is on the downstream side of the center line c ₁ -c ₁ of the nozzle cross section, the more the throttle is opened, the more fuel is injected. Is affected by the pulsation of the engine intake, which causes a time lag in the transfer of fuel to the engine combustion chamber,
Stable 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-mentioned object, the present invention is fixed to a tip end surface of a piston for varying the inner cross section of an intake passage, has a plurality of fuel ejection holes along a longitudinal direction, and has a fuel inside. Of a carburetor having a closed cylindrical shape having a flow path formed therein, and slidably fitted into the needle jet so that fuel in the float chamber can be ejected from the fuel ejection hole into the intake passage. In the injection nozzle, the angle from the center line in the direction substantially orthogonal to the airflow flowing through the intake passage in the cross section of the nozzle from the mounting position of the fuel ejection hole to the piston to the predetermined length portion is downstream from the injection nozzle.
(0 degrees ≦ Θ <90 degrees), and at other lengths, an angle 下流 (Θ = 90 degrees) from the center line to the downstream side
It is characterized by being arranged in.

[0010]

According to the present invention, according to the present invention, when the throttle valve is at a low opening degree, fuel flows from the fuel injection hole arranged at a position of 0 ° ≦ Θ <90 ° which is easy to ride the airflow in the intake passage. When the throttle valve is at a high opening, the fuel is mainly supplied from a fuel outlet disposed at a position of Θ = 90 ° which is not affected by the pulsation of the engine intake. It is designed to cope with both the opening degree and the high opening degree.

[0011]

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 when the present invention is applied to a sliding valve type 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 thereof (see FIGS. 2 to 4).

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.

In the present invention, the fuel injection hole formed in the nozzle is located downstream from a center line in a direction substantially orthogonal to the airflow flowing through the intake passage in the cross section of the nozzle from a position where the fuel injection hole is attached to the piston to a predetermined length. Angle to the side Θ (0 degrees ≤
Θ <90 °), and the other lengths are arranged at an angle Θ (Θ = 90 °) downstream from the center line.

That is, in the embodiment, as shown in FIGS. 2 and 3, from the nozzle mounting surface to the length of １ ／ of the entire nozzle length, the fuel outlet 14 is substantially equal to the airflow flowing through the intake passage 10 in the cross section of the nozzle. Center line c ₁ − in the orthogonal direction
Place from c ₁ to the downstream position of the angle theta (0 ° ≦ theta <90 °), also in the nozzle portion of 1/4 or more the length of the nozzle total length, the fuel ejection holes as shown in FIGS. 2 and 4 14 is disposed downstream of the center line c ₁ -c ₁ by an angle Θ (Θ = 90 degrees). As described above, from the nozzle mounting surface to the length of 1/4 of the total nozzle length, the fuel ejection hole 14 is aligned with the center line.
By providing the fuel flow downstream from c ₁ -c _{1 at an} angle Θ (0 degrees ≦ Θ <90 degrees), the fuel flow atomized from the fuel ejection holes 14 becomes a narrow angle, and the center of the air flow in the intake passage 10 is fast. Supplied centrally. At the same time, the fuel ejected from the fuel ejection holes 14 is affected by the engine intake pulsation, and a part of the fuel is blown back to the side opposite to the airflow direction. However, when the throttle opening is low as shown in FIG. The influence is small, and the amount of fuel blown back at this time can be suppressed to some extent .

Further, the nozzle total length 1 / 4-4 / in the nozzle portion of up to 4 wherein the fuel injection holes 14 center line _c 1 -c ₁
By providing the downstream side of the angle theta (theta = 90 degrees) from when the throttle high degree as shown in FIG. 6, so that it injects fuel mainly less susceptible position of the engine intake air pulsation (However, a small amount of fuel injection is also performed from the fuel injection hole 14 provided at a position where the fuel can easily enter the airflow (0 degrees ≦ Θ <90 degrees)). Also in this case, the fuel ejection 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. However, the amount of fuel blown back at this time can be considerably suppressed by disposing the fuel ejection holes 14 on the back side of the nozzle. The fuel that is blown back at this time is dispersed and present near the intake manifold in the intake passage 10, and is taken into the cylinder before the next explosion step and is effectively used.

Note that all the fuel ejection holes 14 are uniformly angled Θ
(Especially 0 degrees ≤ Θ ≤ 45 degrees)
When the throttle opening is high, the fuel injected from the fuel injection hole 14 is blown back to the side opposite to the airflow direction under the influence of the engine intake pulsation, so that a time lag (time lag) is reached until the fuel reaches the combustion chamber of the cylinder. Shift). This time lag is not so problematic in a four-stroke engine having one suction stroke per four strokes of the piston, but is not significant in a two-stroke engine having one suction stroke per two strokes of the piston. This is particularly problematic because there is not enough time.

Further, the fuel injection holes 14, 14 are formed as shown in FIG.
The nozzles are provided substantially symmetrically with respect to the center line c ₂ -c ₂ of the nozzle cross section in the direction along the airflow flowing through the intake passage 10 as shown in FIG. As a result, the injected atomized fuel is supplied to the intake passage 10
In this case, it is possible to distribute the multi-injection nozzles 13 substantially evenly to the left and right with respect to the axis. Here, the symmetry means that the angle Θ between the right ejection hole 14 and the left ejection hole 14 with respect to the center line c ₂ -c ₂ in FIG. 3 is the same.

It should be noted that the fuel injection hole 14 is aligned with the center line c _1-
When the c ₁ angle theta (0 ° ≦ theta <90 °) only provided downstream of the position, the fuel injection holes 14 are provided two on the left and right side of the nozzle, in the case of an angle theta = 90 degrees the fuel injection holes 14 Naturally becomes one.

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.

[0020]

As described above, the present invention does not simply set the fuel ejection hole in an unspecified direction with respect to the airflow as in the prior art, but sets the fuel ejection hole in the nozzle in accordance with the throttle opening. When the throttle is at a low opening, the fuel flow from the fuel ejection hole provided at a position where the fuel can easily flow in the throttle is concentrated at the center of the intake passage where the airflow is fast, and When the opening is high, fuel can be injected mainly from the fuel injection holes provided at positions that are hardly affected by engine intake pulsation.In each case, fuel atomization and followability are improved to improve engine combustion. Fuel can be supplied to the room. In addition, according to the present invention, by arranging the fuel ejection holes on the back side of the nozzle, the amount of fuel that is blown back by the influence of the engine intake pulsation particularly at a high throttle opening is considerably suppressed. Are dispersed near the intake manifold in the intake passage and are effectively used in the next explosion process, so that stable engine rotation can be ensured.

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 an enlarged sectional view of a nozzle.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a diagram showing a nozzle position when the throttle opening is low.

FIG. 6 is a diagram showing a nozzle position when the throttle opening is high.

FIG. 7 is a schematic longitudinal sectional view of a conventional sliding valve carburetor.

FIG. 8 is a sectional view taken along line CC of FIG. 7;

FIG. 9 is a sectional view taken along line CC of FIG. 7;

[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 7/17 F02M 9/02-9/06 F02M 19/03-19/06

Claims (2)

(57) [Scope of request for utility model registration] 1. A closed cylindrical shape having a plurality of fuel ejection holes along a longitudinal direction and having a fuel flow passage formed therein, which is fixed to a tip end surface of a piston that varies an inner cross section of an intake passage, and In a multi-injection nozzle of a carburetor which is slidably fitted into a needle jet and is capable of ejecting fuel in a float chamber from the fuel ejection hole into an intake passage, the fuel ejection hole is attached to a piston from a mounting position. Up to a predetermined length, an angle Θ (0 degrees ≦ 0 degrees) from the center line in a direction substantially perpendicular to the airflow flowing through the intake passage in the nozzle cross section toward the downstream side
Θ <90 degrees), and the other length portion is arranged at an angle Θ (Θ = 90 degrees) downstream from the center line. 2. A multi-injection nozzle for a carburetor, wherein the fuel ejection holes are provided substantially symmetrically with respect to a center line of a cross section of the nozzle.