JP2002349353A - Piston type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston type carburetor capable of improving the acceleration response at the time of acceleration by atomizing the fuel ejected from a main nozzle and preventing the fuel from diffusing into an intake passage. SOLUTION: A plurality of pores 44 for the auxiliary air are provided at an upper stream side of an end projecting part 42 projecting into an intake passage 36 in a main nozzle 40. The air passed through the pore 44 for the auxiliary air is mixed with the fuel ejected from an opening of the main nozzle 40 so as to promote to atomize the fuel. The air passed through the pore 44 flows from an upper stream to a down stream of the intake passage 36, and then the fuel ejected from the opening of the main nozzle 40 becomes difficult to adhere to an inner wall of the intake passage 36 without diffusing horizontally. The response at the time of acceleration can be improved by atomizing the fuel and preventing the intake passage 36 from adhering to the wall face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston type carburetor in which the amount of fuel injected from a main nozzle is adjusted by a jet needle attached to a piston.

[0002]

2. Description of the Related Art Conventionally, there has been known a piston type carburetor in which a jet needle inserted into a main nozzle is displaced by a piston to adjust a discharge amount of fuel discharged from a gap between the main nozzle and the jet needle.
The main nozzles used in the piston type vaporizer are selectively used as a bleed type main nozzle and a primary type main nozzle according to the purpose.

FIG. 6 shows a bleed-type main nozzle. The bleed-type main nozzle 10 has a substantially cylindrical shape, and is formed with a large number of bleed holes 12 communicating between the inside and outside of the cylindrical shape at positions below the oil level in the axial direction and around the periphery. Inside the main body 14 of the vaporizer,
An intake passage 16 and a main air passage 18 are formed. Further, a cylindrical air introduction space 20 is formed between the outside of the main nozzle 10 and the main body 14, and the air introduction space 20 communicates with the main air passage 18. The carburetor has an intake passage 1
6 is provided with a piston 22 for changing the cross section, and a jet needle 24 attached to the piston 22 and inserted into the bleed-type main nozzle 10. The bleed air is introduced from the main air passage 18 into the air introduction space 20, and from there through a number of bleed holes 12 into the internal space of the cylindrical main nozzle 10. Fuel and bleed air are mixed in the internal space of the main nozzle 10, and a mixture of the fuel and bleed air is ejected from the opening of the main nozzle 10 into the intake passage 16.

Next, FIG. 7 shows a primary type main nozzle. Primary type main nozzle 30
Has a substantially cylindrical shape, and has a communication hole 32 near the upper portion for communicating the inside and outside of the tube. That is, the primary type main nozzle 30 does not have the bleed hole 12 like the bleed type main nozzle 10 shown in FIG. In the carburetor body 34, an intake passage 36,
A main air passage 38 is formed. The main air passage 38 directly communicates with the communication hole 32 of the primary type main nozzle 30. The vaporizer has a piston 22 and a jet needle 2 attached to the piston 22 for insertion into the primary type main nozzle 30.
4 is provided. The air introduced from the main air passage 38 is introduced into the internal space above the main nozzle 30 from the communication hole 32, and the fuel and the air are mixed at the introduction position. The fuel mixed with the air is ejected from the opening of the main nozzle 30 to the intake passage 36.

[0005] The primary type main nozzle 30 shown in FIG. 7 does not have the bleed hole 12 like the bleed type main nozzle 10 shown in FIG. 6, so that the air is better mixed with the fuel than the bleed type main nozzle 10. It is not in a state where it was left. For this reason, it is known that the particle diameter of the fuel discharged from the primary type main nozzle 30 is relatively coarse as compared with that discharged from the bleed type main nozzle 10.

FIG. 8 is a characteristic diagram showing the relationship between the engine speed and the fuel flow rate. The use of the primary type main nozzle 30 having a coarse fuel particle diameter has the purpose of raising the flow curve toward a higher boost side as compared with the case of using the bleed type main nozzle 10 having a small fuel particle diameter. Therefore, a bleed hole cannot be provided.

[0007]

In the primary type main nozzle 30, fuel having a coarser particle diameter is ejected than in the bleed type in which the fuel can be sufficiently atomized. Therefore, when the primary type main nozzle 30 is used, there is a problem in that the arrival of fuel from the main nozzle nozzle into the cylinder is delayed, and the accelerator response is delayed. Further, as shown in FIG. 9 (in FIG. 9, the distal end protruding portion 39 of the main nozzle 30 has a shape in which the downstream side is cutout), the fuel injected from the conventional primary type main nozzle 30 is cut in the left and right directions. This causes a problem that a part of the fuel adheres to a wall surface of the intake passage, and the accelerator response at the time of acceleration is further delayed.

The present invention has been made in view of the above points, and aims to improve the accelerator response at the time of acceleration by atomizing the fuel ejected from the main nozzle and preventing the fuel from diffusing into the intake passage. It is an object of the present invention to provide a piston type carburetor.

[0009]

In order to achieve the above object, a piston type carburetor according to the present invention comprises a carburetor body, an intake passage formed in the carburetor body, and a cross section of the intake passage variable. Piston, a primary type main nozzle that opens to the intake passage, and a jet carburetor having a jet needle fixed to the piston and inserted into the main nozzle, wherein a tip protrusion of the main nozzle that protrudes into the intake passage is provided. A small hole for auxiliary air is provided on the upstream side.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a main part showing an embodiment of a piston type vaporizer of the present invention. 1, the same reference numerals as those in FIG. 7 indicate the same members. The present invention uses a primary type main nozzle.
The only member different from the above is the main nozzle. The primary type main nozzle 40 of FIG. 1 is provided with one or a plurality of small holes for auxiliary air 44 on the upstream side (on the upstream side of the intake passage) of the tip protrusion 42 which protrudes into the intake passage 36.

As shown in FIGS. 2 and 3, the tip projection 42 of the main nozzle 40 has a shape obtained by cutting a cylindrical shape substantially in half in the axial direction, and the tip projection 42 has an opening 4.
6 upstream. A plurality of small holes for auxiliary air 44 are provided in the circumferential direction at the horizontal position on the upstream side of the tip protrusion 42. As a result, the small holes 4 for the auxiliary air
The air having passed through 4 flows downstream near the opening 46 of the main nozzle 40. This small hole for auxiliary air 4
4, the opening 46 of the main nozzle 40 is provided.
The auxiliary air that has passed through the small holes for auxiliary air 44 is mixed with the fuel that is almost not bleeded and is ejected from the fuel cell, thereby promoting the atomization of the fuel. That is, in the present invention, since the primary type main nozzle 40 is used, the flow rate curve can be made to stand toward the high boost side as shown in FIG. 8, and the atomization of the fuel can be promoted. .

Since the auxiliary air flowing through the auxiliary air small holes 44 flows from the upstream to the downstream in the intake passage 36, as shown in FIG. 2, the fuel injected from the opening 46 of the main nozzle 40 9 is less likely to diffuse laterally. As a result, the fuel ejected from the opening 46 of the main nozzle 40 hardly adheres to the inner wall of the intake passage 36.

The shape of the tip of the main nozzle 40 is as follows:
In addition to the cylindrical shape shown in FIGS. 2 and 3 which is cut in half in the axial direction, a cylindrical distal end projecting portion 48 shown in FIGS. 4 and 5 may be used. Also in this case, the auxiliary air small holes 5 are provided on the upstream side (upstream side of the intake passage) of the tip projecting portion 48.
0 is formed. FIGS. 4 and 5 show a state in which a plurality of auxiliary air small holes 50 are formed in the axial direction of the distal end projection 48. However, also in the cylindrical leading end protruding portion 48, a plurality of auxiliary air small holes 50 may be provided in the circumferential direction at the horizontal position on the upstream side, as in FIGS. Further, as shown in FIG. 5, a plurality of air passage holes 52 may be formed on the downstream side (downstream of the intake passage) of the cylindrical distal end projection 48. By using the air passage hole 52, a mixture in which the air and the fuel introduced into the inside of the tip projection 48 from the auxiliary air small hole 50 are mixed at the tip projection 48 is smoothly ejected through the downstream intake passage. Can be done.

[0014]

As described above, according to the piston type carburetor according to the present invention, the small hole for the auxiliary air is provided on the upstream side of the tip protruding portion of the main nozzle protruding into the intake passage. The auxiliary air passing through the small holes for the auxiliary air is mixed with the fuel ejected from the opening of the main nozzle, and can promote atomization of the fuel. Further, the fuel is not diffused laterally by the auxiliary air passing through the small holes for the auxiliary air, so that the fuel is less likely to adhere to the inner wall of the intake passage. As a result, the fuel ejected from the main nozzle into the intake passage is atomized and efficiently supplied to the engine, so that the response during acceleration can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing an embodiment of a piston type vaporizer according to the present invention.

FIG. 2 is a diagram showing a flow of fuel ejected from a main nozzle.

FIG. 3 is a perspective view of a main part of a main nozzle used in the present invention.

FIG. 4 is a perspective view of a main part of another main nozzle used in the present invention.

FIG. 5 is a perspective view of a main part of another main nozzle used in the present invention.

FIG. 6 is a cross-sectional view of a conventional piston type vaporizer using a bleed type main nozzle.

FIG. 7 is a sectional view of a conventional piston type vaporizer using a primary type main nozzle.

FIG. 8 is a characteristic diagram showing a relationship between an engine speed and a fuel flow rate for a bleed type main nozzle and a primary type main nozzle.

FIG. 9 is a diagram showing a flow of fuel ejected from a conventional primary type main nozzle.

[Explanation of symbols]

 22 Piston 24 Jet Needle 36 Intake Path 40 Main Nozzle 42 Tip Projection 44 Small Auxiliary Air Hole 48 Tip Projection 50 Small Auxiliary Air Hole 52 Air Passing Hole

Claims (4)

[Claims] 1. A carburetor body, an intake passage formed in the carburetor body, a piston for varying the cross section of the intake passage, a primary type main nozzle opening to the intake passage, and fixed to the piston. A piston-type carburetor having a jet needle inserted into the main nozzle, wherein a small hole for auxiliary air is provided on the upstream side of a tip protruding portion of the main nozzle protruding into the intake passage. . 2. A plurality of small holes for auxiliary air are provided at the same height position of the front end protruding portion.
The piston type vaporizer described. 3. The piston type carburetor according to claim 1, wherein a plurality of said small holes for auxiliary air are provided in an axial direction of said main nozzle. 4. A plurality of air passage holes for passing a mixture of air and fuel having passed through the small holes for auxiliary air at a downstream side of the tip protrusion. 3. The piston type vaporizer according to 3.