JP3708568B2 - Vaporizer fuel supply mechanism - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a mechanism for supplying an emulsion of fuel and air to a venturi portion of a vaporizer.
[0002]
[Prior art]
Normally, in the carburetor, an emulsion of fuel and air is ejected from the needle jet into the intake passage, and the emulsion and the air supplied from the upstream of the intake passage are mixed and supplied to the engine downstream of the intake passage. The emulsion is generated by mixing the fuel supplied through the main jet located in the float chamber and the air supplied through the air passage in the bleed chamber, and is supplied into the needle jet.
[0003]
[Problems to be solved by the invention]
As described above, bubbles are included in the emulsion, and when these bubbles stay in the needle jet to form a group of bubbles, it becomes difficult for the emulsion to be ejected into the intake passage by the group of bubbles. The proportion of air in the mixture supplied to the engine increases. On the other hand, when the group of bubbles is discharged into the intake passage and the emulsion is successfully ejected into the intake passage, the amount of the emulsion ejected into the intake passage relatively increases, The proportion of air is relatively reduced. By repeating such a cycle, the air-fuel ratio (A / F value) fluctuates greatly periodically, stable fuel supply is not performed, and the engine operating state becomes unstable.
[0004]
The present invention has been made in view of the above problems, and smoothly discharges air bubbles generated in the needle jet to the intake passage, thereby suppressing the fluctuation of the A / F value and supplying fuel stably. It is an object of the present invention to provide a carburetor fuel supply mechanism.
[0005]
[Means for Solving the Problems]
A fuel supply mechanism for a carburetor according to the present invention includes a needle jet that opens into an intake passage and ejects fuel into the intake passage, and a fuel supply means having an emulsion passage that mixes and supplies fuel and air to the needle jet. One end of the emulsion passage is opened in the inner wall surface of the needle jet, and the opening is offset from the central axis of the needle jet.
[0006]
The emulsion passage may be formed in the needle jet and may include an offset passage extending along the tangential direction of the inner wall surface of the needle jet.
[0007]
The emulsion passage may be bent near the outer peripheral wall of the needle jet.
[0008]
The emulsion passage is formed in the needle jet, and is connected to the offset passage extending along the outer peripheral direction of the needle jet, and to the bleed passage through the outer peripheral wall of the needle jet, and extends toward the central axis of the needle jet. And a bleed passage formed in the vaporizer body.
[0009]
【Example】
The present invention will be described below with reference to illustrated embodiments.
FIG. 1 is a cross-sectional view of a carburetor provided with a fuel supply mechanism according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the fuel supply mechanism of FIG.
[0010]
An intake passage 12 is formed inside the carburetor body 10, and an air funnel 14 is provided upstream of the intake passage 12. Further, a negative pressure valve 16 that can be displaced in a direction perpendicular to the axis of the intake passage 12 is provided, and the negative pressure valve 16 is supported by the vaporizer body 10 so as to be movable up and down and slidable. As will be described later, the negative pressure valve 16 moves up and down in accordance with the negative pressure in the intake passage 12, thereby changing the flow path area in the intake passage 12. A jet needle 18 is integrally fixed to the negative pressure valve 16, and the amount of fuel supplied into the intake passage 12 is controlled by raising and lowering operations of the negative pressure valve 16 and the jet needle 18.
[0011]
An end 16 a of the negative pressure valve 16 protrudes outside the vaporizer body 10. An outer peripheral edge 21 a of the diaphragm 21 is fixed to the outer wall surface of the vaporizer body 10, and an inner peripheral edge 21 b of the diaphragm 21 is connected to the end 16 a of the negative pressure valve 16. A cover 22 that covers the diaphragm 21 is attached to the outer wall surface of the vaporizer body 10, and a negative pressure chamber 24 is formed by the cover 22 and the diaphragm 21. The negative pressure chamber 24 communicates with the intake passage 12 through a hole (not shown) formed in the negative pressure valve 16. The spring 20 is provided between the negative pressure valve 16 and the cover 22 and biases the negative pressure valve 16 diagonally downward (intake passage 12 side). Accordingly, the negative pressure valve 16 is set at a position where the negative pressure in the intake passage 12 and the elastic force of the spring 20 are balanced, thereby changing the flow passage area of the intake passage 12.
[0012]
The jet needle 18 extends through the negative pressure valve 16 and is integrally fixed to the negative pressure valve 16 at its upper end. The jet needle 18 extends downward and is inserted into a jet needle storage chamber 34 of a needle jet 30 described later. A float chamber 28 is formed obliquely below the vaporizer body 10, and a certain amount of fuel is stored in the float chamber 28.
[0013]
The vaporizer body 10 is provided with a cylindrical needle jet 30. The upper end portion of the needle jet 30 protrudes into the intake passage 12, and the lower end portion of the needle jet 30 faces the float chamber 28. The lower end portion of the needle jet 30 is closed by a lid member 32, and a jet needle 18 is provided in a jet needle storage chamber 34 formed inside the needle jet 30 and the lid member 32 so as to be movable up and down. An offset passage 37 constituting a part of an emulsion passage 36 described later is formed on the side wall of the needle jet 30.
[0014]
A cylindrical support member 48 is provided below the needle jet 30 of the vaporizer body 10, and this support member 48 protrudes into the float chamber 28. A bleed chamber 42 is formed inside the support member 48, and a cylindrical member 44 in which a large number of air ejection holes 46 are formed is provided. A gap is formed between the outer wall surface of the cylindrical member 44 and the inner wall surface of the support member 48, that is, the inner and outer sides of the cylindrical member 44 communicate with each other through the air ejection holes 46. The upper end portion of the cylindrical member 44 faces a bleed passage 38 constituting a part of the emulsion passage 36, and the lower end portion of the cylindrical member 44 is close to the main jet 40 fixed to the support member 48. The main jet 40 faces the float chamber 28.
[0015]
The bleed chamber 42 outside the tubular member 44 communicates with the atmosphere via an air inlet (not shown) formed in the vaporizer body 10. Therefore, air flows into the bleed chamber 42 inside the cylindrical member 44 through the air ejection hole 46 and mixes with the fuel supplied from the main jet 40, thereby generating an emulsion. That is, this emulsion is a fuel containing air and is supplied to the emulsion passage 36 communicating with the upper end of the bleed chamber 42 by the action of the negative pressure generated in the intake passage 12.
[0016]
3 is a cross-sectional view taken along the line III-III in FIG. 1, and FIG. 4 is a cross-sectional view of the needle jet 30 in the vicinity of the intake passage 12 side.
[0017]
The emulsion passage 36 is bent in the vicinity of the outer peripheral wall of the needle jet 30, and includes an offset passage 37 extending from the bent portion to the jet needle storage chamber 34 and a bleed passage 38 extending to the bleed chamber 42 of the cylindrical member 44. Is done.
[0018]
The bleed passage 38 is formed in the carburetor main body 10 and extends toward the central axis O along the axis of the jet needle storage chamber 34. The bleed passage 38 is connected to the offset passage 37 at the upper end and is connected to the upper end of the bleed chamber 42 at the lower end.
[0019]
The offset passage 37 is formed on the side wall of the needle jet 30, opens to the inner wall surface of the needle jet 30 at one end and faces the jet needle storage chamber 34, opens to the outer peripheral wall of the needle jet 30 at the other end, and bleeds. The upper end of the passage 38 is connected. The offset passage 37 is offset from the central axis O along the direction in which the jet needle storage chamber 34 extends in the inner wall surface opening. The offset passage 37 extends along the tangential direction of the inner wall surface of the needle jet 30 (the outer peripheral surface of the jet needle storage chamber 34). That is, in this opening, a part 37 a of the side wall of the offset passage 37 is smoothly connected along the tangential direction of the inner wall surface of the needle jet 30.
[0020]
Next, the operation of this embodiment will be described.
In the engine operating state, the jet needle storage chamber 34 is filled with the emulsion supplied from the emulsion passage 36. When the accelerator mechanism is operated from the idle operation state, a throttle valve (not shown) provided on the downstream side of the negative pressure valve 16 is opened and the negative pressure in the intake passage 12 increases, the negative pressure valve 16 rises accordingly, and the intake air The flow passage area in the passage 12 is increased and the intake air amount is increased. Further, when the negative pressure valve 16 is raised, the gap between the inner wall surface of the needle jet 30 and the jet needle 18, that is, the opening area of the needle jet 30 is enlarged, and the amount of fuel sprayed into the intake passage 12 is increased.
[0021]
Since the offset passage 37 is offset from the central axis O of the needle jet 30 and extends along the tangential direction of the inner wall surface of the needle jet 30, the offset passage 37 is supplied from the bleed chamber 42 through the bleed passage 38 into the needle jet 30. The fuel and air emulsion swirls in the jet needle storage chamber 34 (see arrow R in FIG. 3). Therefore, the bubble group does not stay in the jet needle storage chamber 34, and the flow path resistance between the inner wall surface of the needle jet 30 and the jet needle 18 is always constant. For this reason, the fluctuation | variation of the quantity of the emulsion supplied to the intake passage 12 from the needle jet 30 is suppressed, and the fluctuation | variation of the A / F value in the intake passage 12 is suppressed low.
[0022]
5 and 6 show the configuration of the comparative example, and correspond to FIGS. 3 and 4 of the present embodiment. As illustrated, in the comparative example, the emulsion passage 36 extends toward the central axis O of the jet needle storage chamber 34.
[0023]
In the comparative example, when the emulsion is supplied from the emulsion passage 36 to the jet needle storage chamber 34, the bubbles A contained in the emulsion stagnate around the jet needle 18 in the jet needle storage chamber 34, and the jet needle storage. It stays in the step S formed in the chamber 34. When the staying bubbles A increase and a bubble group is formed, the flow of emulsion ejected from the jet needle storage chamber 34 into the intake passage 12 is inhibited, and the amount of emulsion supplied to the intake passage 12 decreases. . As a result, the air component in the fuel supplied to the downstream side of the intake passage 12 increases, and the A / F value increases. On the other hand, when the bubble group is discharged into the intake passage 12, the emulsion is favorably ejected into the intake passage 12, so that the air component in the fuel is relatively reduced and the A / F value is relatively reduced. Will decrease. In this way, the amount of emulsion supplied to the intake passage 12 becomes unstable, and the A / F value in the fuel supplied downstream of the intake passage 12 varies greatly.
[0024]
On the other hand, in the present embodiment, since the bubble group does not stay in the jet needle storage chamber 34 as described above, the amount of emulsion supplied to the intake passage 12 is stabilized, and the A / F value in the intake passage 12 is reduced. Fluctuation is kept low.
[0025]
FIGS. 7 and 8 are diagrams showing variations in the A / F value according to the configuration of the comparative example and the configuration of the present embodiment, respectively. In the figure, the vertical axis represents the A / F value, and the horizontal axis represents the elapsed time. As shown in the figure, according to the configuration of the comparative example, the A / F value fluctuates greatly, whereas according to the configuration of the present embodiment, the amplitude of the A / F value is remarkably reduced. Yes.
[0026]
In the present embodiment, the offset passage 37 extends along the tangential direction of the inner wall surface of the needle jet 30, but may be further inclined in the axial direction of the needle jet 30.
[0027]
【The invention's effect】
As described above, according to the present invention, bubbles generated in the needle jet are smoothly discharged into the intake passage, and therefore, an effect that the fluctuation of the A / F value is suppressed low and the engine operating state is stabilized can be obtained. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a vaporizer provided with a fuel supply mechanism according to an embodiment of the present invention.
2 is a cross-sectional view of the vicinity of a fuel supply mechanism in FIG.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a cross-sectional view of the vicinity of the intake passage side of the needle jet of FIG. 1. FIG.
5 is a cross-sectional view similar to FIG. 3, showing a configuration of a comparative example.
6 is a cross-sectional view similar to FIG. 4, showing a configuration of a comparative example.
FIG. 7 is a diagram showing a change in A / F value according to the configuration of a comparative example.
FIG. 8 is a diagram showing a change in A / F value according to the configuration of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Vaporizer body 12 Intake passage 16 Negative pressure valve 28 Float chamber 30 Needle jet 34 Jet needle storage chamber 36 Emulsion passage 37 Offset passage 38 Bleed passage 40 Main jet 42 Bleed chamber 44 Cylindrical member A Bubble

Claims (4)

  A needle jet that opens to the intake passage and ejects fuel into the intake passage; and a fuel supply means that has an emulsion passage that mixes and supplies fuel and air to the needle jet. One end of the emulsion passage is a needle jet A fuel supply mechanism for a carburetor, wherein the fuel supply mechanism is opened to the inner wall surface of the carburetor and the opening is offset from the central axis of the needle jet.   2. The fuel supply mechanism for a carburetor according to claim 1, wherein the emulsion passage includes an offset passage formed in the needle jet and extending along a tangential direction of an inner wall surface of the needle jet.   The fuel supply mechanism for a carburetor according to claim 1, wherein the emulsion passage is bent in the vicinity of an outer peripheral wall of the needle jet. The emulsion passage, while being formed in the needle jet, an offset passage extending along the outer circumference of the needle jet, as well as connected with the outer peripheral wall of the pre-Symbol needle jet, extending towards the needle jet central axis The carburetor fuel supply mechanism according to claim 1, further comprising a bleed passage formed in the carburetor body.

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