JP2578475Y2 - Evaporator injection nozzle - 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 in an injection nozzle of a carburetor which is slidably fitted into a needle jet and ejects fuel into an intake passage as the needle jet moves up and down.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a tapered jet needle 14 fixed to a lower end surface of a piston 12 for varying the inner cross section of an intake passage 10 has a structure for ejecting fuel into an intake passage of a carburetor. Is slidably fitted into the needle jet 16 and fuel is injected from the gap 18 between the jet needle 14 and the needle jet 16. However, in this case, since the fuel is ejected from the position where the airflow in the venturi section 20 is slow, there is a possibility that the wall flow increases or the fuel is sucked in with a delay with respect to a change in the operation state.

In order to improve this, Japanese Utility Model Application Laid-Open No. 2-10106
No. 3 was proposed. In this technique, as shown in FIG. 6, a pipe-shaped injection nozzle 22 is fixed to the tip of a piston 12 that changes the internal cross section of the intake passage 10, and the injection nozzle 22 is slidably inserted into the needle jet 16. The fuel injection nozzle 22 has a plurality of fuel injection holes 24 formed in an outer peripheral portion thereof. According to this, since the fuel is ejected from the float chamber (not shown) into the intake passage 10 via the injection nozzle 22, the dispersion of the fuel is averaged, and the atomization state is improved.

[0004]

By the way, taking a negative pressure type carburetor as an example, when the amount of air flowing through the venturi section is very small and the negative pressure is small at a low throttle opening, an attempt to move the piston results in a very small amount of fuel. The primary area is set between the tip of the piston and the venturi in order to secure a certain amount of air even at a low throttle opening. When the fuel is ejected from the ejection hole 24 of the injection nozzle 22 into the primary area, it is necessary to narrow down the fuel to some extent, so that the diameter of the ejection hole 24 has to be reduced as much as possible. However, when the fuel injection hole is minimized, there is a problem that the fuel flow rate at a low throttle opening becomes unstable and the workability deteriorates.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a carburetor capable of stabilizing a fuel flow rate at a low throttle opening and improving workability. An object of the present invention is to provide an injection nozzle.

[0006]

In order to achieve the above object, the present invention relates to a float chamber which is fixed to a piston which changes the internal cross section of an intake passage, is slidably fitted into a needle jet, and moves up and down with the vertical movement thereof. In the injection nozzle of the carburetor that ejects the fuel inside the intake passage into the intake passage, the upper part near the piston has a large diameter and the lower part has a small diameter and a solid taper part. And a hollow cylindrical portion having a plurality of fuel ejection holes formed along a longitudinal direction and having a passage formed therein.

[0007]

[Function] Generally, it is difficult to finely adjust the fuel at a low throttle opening. Therefore, according to the present invention, the fuel can be controlled at a low throttle opening by ejecting fuel from a gap between a tapered portion of a nozzle and a needle jet. Also, when the throttle opening increases and the amount of air increases, fuel is mainly ejected from the fuel ejection holes of the hollow cylindrical portion so that fuel can be supplied to the central portion of the intake passage where airflow is fast. I have.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view when the present invention is applied to a negative pressure carburetor. In the figure, an injection nozzle 34 is fixed to the center of the tip of a piston 32 that varies the cross section in the intake passage 30, and a needle jet 38 is formed directly below the injection nozzle 34 on the main body 36 side of the carburetor. . Then, the injection nozzle 34 is slidably fitted into the needle jet 38 to thereby make the piston 3
The fuel in the float chamber 40 is jetted into the intake passage 30 by the negative pressure due to the vertical movement of 2.

In the present invention, the injection nozzle 34 has a solid tapered portion having a large diameter on the upper side near the piston 32 and a small diameter on the lower side, and a fuel flow path formed inside and connected below the tapered portion. And a hollow cylindrical portion having a plurality of fuel ejection holes along the longitudinal direction.

As shown in FIGS. 1 and 2, the injection nozzle 34 has a solid tapered portion 42 having a large diameter on the upper side D and a small diameter on the lower side d near the piston 32, and a lower part of the tapered portion 42. It has a hollow cylindrical portion 48 which is connected and has a fuel flow path 44 formed inside and has a plurality of fuel ejection holes 46 along the longitudinal direction. The large diameter portion D of the tapered portion 42 is slightly smaller than the diameter of the needle jet 38 so as to be able to fit into the needle jet 38, and the hollow cylindrical portion 48 is
2 has a diameter substantially equal to the small diameter portion d.

In the above description, when the throttle opening is low, as shown in FIG.
Fits deeply into the needle jet 38 so that the tapered portion 42 is located at the entrance thereof. In this state, fuel is ejected from the gap 50 between the needle jet 38 and the tapered portion 42 into the intake passage 30. At a high throttle opening, as shown in FIG. 4, the injection nozzle 34 rises with an increase in the amount of air, and the hollow cylindrical portion 48 protrudes from the needle jet 38 so that this portion is located in the intake passage 30. Become. In this state, the fuel is mainly ejected from the fuel ejection holes 46 and also from the gaps 50. In particular, the fuel ejected from the fuel ejection holes 46 is concentrated and supplied to the center of the cross section of the passage where the airflow is fast. It is taken into the engine.

According to this embodiment, when the air flow rate is low, the minute flow rate can be adjusted by the tapered portion 42 of the injection nozzle 34 without using the fuel injection hole 46, and when the air flow rate increases, the fuel injection is mainly performed. Since the fuel is ejected from the holes 46, the diameter of the fuel ejection holes 46 can be increased, and the workability is extremely easy.

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

[0014]

As described above, since the fuel is conventionally ejected from the fuel ejection holes at all throttle openings, the fuel ejection holes have to be machined to a minimum because it is necessary to narrow down the fuel to some extent at a low throttle opening. However, according to the present invention, at a low throttle opening, fuel is jetted from a gap between the needle jet and the nozzle,
When the throttle opening becomes high, fuel is mainly injected from the fuel injection hole.Thus, while stabilizing the small fuel flow rate when the throttle opening is low, the hole diameter of the fuel injection hole is enlarged to improve workability. Can be easier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view when the present invention is applied to a negative pressure type carburetor.

FIG. 2 is an enlarged sectional view of the injection nozzle according to the present invention.

FIG. 3 is a cross-sectional view showing a positional relationship between an injection nozzle and a needle jet when a throttle opening is low.

FIG. 4 is a cross-sectional view showing a positional relationship between an injection nozzle and a needle jet when the throttle opening is high.

FIG. 5 is a cross-sectional view showing a conventional example in which a jet needle is applied to a negative pressure carburetor.

FIG. 6 is a sectional view showing a conventional example in which a multi-injection nozzle is applied to a negative pressure carburetor.

[Explanation of symbols]

 Reference Signs List 30 intake passage 32 piston 34 injection nozzle 38 needle jet 42 taper portion 44 flow passage 46 fuel ejection hole 48 hollow cylindrical portion 50 gap

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02M 19/03-19/06 F02M 7/17 F02M 9/02-9/06

Claims (1)

(57) [Scope of request for utility model registration] An injection nozzle for a carburetor, which is fixed to a piston that changes the cross-section of an intake passage and is slidably fitted into a needle jet and ejects fuel in a float chamber into the intake passage as the needle jet moves up and down. In the above, a solid tapered portion having a large diameter on the upper side and a small diameter on the lower side near the piston, and a fuel flow path formed inside and connected to the lower side of the tapered portion, and a plurality of fuel ejection holes are formed along the longitudinal direction. And a hollow cylindrical portion having the same.