JP2003201920A - Sliding valve carburetor - Google Patents

Abstract

(57) [Problem] To provide a sliding valve type carburetor having a good response response at the time of engine acceleration even when a bypass hole is formed immediately downstream of an opening projection. SOLUTION: An intake passage 102 formed in a carburetor body 101 and having a venturi portion 103, and a sliding valve 10 for changing an opening area of the intake passage in the venturi portion.
4 and the jet needle 109 held by the sliding valve
A main nozzle 106 having an opening in the intake passage wall through which the jet needle is inserted;
6, in a sliding valve type carburetor having an opening projection 108 projecting from the opening and a bypass hole 122 opening downstream of the opening projection, there are a plurality of openings of the bypass hole, At least one of them is provided outside a region Z affected by the flow velocity of the opening projection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding valve type carburetor in which the opening area of a venturi portion is changed by a sliding valve, and more particularly to a technique for improving acceleration response from a low speed region to a high speed region.

[0002]

2. Description of the Related Art The sliding valve (throttle valve) shape of a sliding valve type carburetor has conventionally been round, but recently, a cocoon type or the like has been proposed. It was

FIG. 3 shows a structure of a sliding valve type carburetor using a conventional cocoon type sliding valve, and FIG. 4 shows an enlarged view of the vicinity of the opening of the main nozzle. The vaporizer 100 is a vaporizer main body 1
The intake passage 102 is formed to penetrate 01, and the intake passage 1
The central portion of 02 is the venturi portion 103, and the intake air flows in the direction indicated by the arrow A. The sliding valve 104 is provided substantially at the center of the Venturi portion 103 and moves up and down to raise the intake passage 10
The amount of intake air passing through is adjusted by increasing or decreasing the opening area of 2. As shown in FIG. 4A, the sliding valve 104 is a column having a cross section in which an oval is gently curved, and this is called a cocoon type.

The bottom of the carburetor body 101 is a float chamber 101a in which fuel such as gasoline is held by a float (not shown) so that the height of the liquid surface is always constant.

The carburetor main body 101 has a main nozzle 106 opening to the intake passage 102, the lower part of which is connected to the main jet 107, and the lower end of the main jet 107 is immersed in the fuel in the float chamber 101a. An arc-shaped opening protrusion 108 is provided upright at the opening of the main nozzle 106 of the block 105.

A tapered jet needle 109 is attached to the sliding valve 104, and this is the main nozzle 106.
Has been inserted inside. When the sliding valve 104 moves upward in FIG. 3 and opens the intake passage 102, the main nozzle 10
The jet needle 109 advancing to 6 is the sliding valve 10
Lift up with 4 and jet needle 109
The diameter of the portion of the main nozzle 106 at the opening position gradually decreases, and the main nozzle 106 increases the opening area according to the throttle opening.

When the slide valve 104 slides in the vertical direction, the opening area of the venturi portion 103 formed in the intake passage 102 of the carburetor body 101 changes and passes through it in the direction of arrow A in FIG. The amount of air intake changes. Since the negative pressure of the Venturi portion 103 changes in accordance with this change, the main jet 107 depending on the magnitude of this negative pressure.
Fuel (gasoline, etc.) sucked out of the float chamber 101a via the main nozzle 106 is ejected from the main nozzle 106, becomes a mixture, and is supplied to an engine (not shown).
The amount of gasoline ejected from the main nozzle 106 is an amount corresponding to the opening area determined by the diameter of the jet needle 109.

A pilot jet 110 is provided adjacent to the main jet 107. Main nozzle 10
At the opening end of No. 6, there is an opening protrusion 108 protruding into the intake passage 102, but the bypass hole 111 at the tip of the pilot jet 110 is located in the vicinity of this opening protrusion 108.

As shown in FIG. 4B, the bypass hole 11
1 is on the center line b of the opening protrusion 108, and this center line b is a line parallel to the center axis a of the intake passage 102, and is in the same direction as the intake air flowing direction A.

The bypass hole 111 supplements the fuel shortage in the low speed region including the off idling state where the sliding valve 104 is slightly opened. Especially, when the engine is accelerated from low speed to high speed, it is necessary to smoothly increase the rotation of the engine.

When the sliding valve 104 is slightly open, the intake air pressure of the engine causes an arrow A from the gap below the sliding valve 104.
Since the air flows vigorously in the direction, the negative pressure around the opening of the bypass hole 111 becomes large. Therefore, the fuel can be sucked up from the pilot jet 110, and the fuel can be additionally ejected from the bypass hole 111 into the intake passage 102.

[0012]

If the sliding valve 104 has a circular cross section, the distance between the opening projection 108 and the bypass hole 111 may be within the range of the radius of the sliding valve 104. , Can be big. However, sliding valve 1
When 04 becomes a cocoon type, the dimension of the sliding valve 104 in the direction of the central axis a becomes small, and the bypass hole 111 must be provided in the immediate vicinity of the opening protrusion 108.

Therefore, in the conventional cocoon-type sliding valve, the bypass hole 111 is formed immediately downstream of the opening protrusion 108. Therefore, the opening protrusion 108 becomes a folding screen, the air flow passing over the bypass hole 111 becomes weak, the negative pressure around the outlet of the bypass hole 111 of the intake passage 102 becomes small, and the amount of fuel injection becomes insufficient. . As a result, there is a problem in that the speed of increase in engine rotation becomes slow when the engine is accelerated from low speed to high speed, that is, the response response is poor and the acceleration feeling is insufficient.

The present invention solves such a problem. Even when a bypass hole is formed immediately downstream of the opening protrusion, the pressure around the bypass hole outlet of the intake passage is increased to increase the pressure from the bypass hole. It is an object of the present invention to provide a sliding valve type carburetor which ejects sufficient fuel and has a good response response at the time of engine acceleration.

[0015]

In order to solve the above problems, a sliding valve type carburetor of the present invention is an intake passage having a venturi portion formed in a carburetor body, and an opening of the intake passage in the venturi portion. A sliding valve of which the area is changed, a jet needle held by the sliding valve, a main nozzle having an opening through which the jet needle is inserted in the intake passage wall, and a projection provided at the opening of the main nozzle An opening protrusion and a bypass opening downstream of the opening protrusion;
In the sliding valve type carburetor having the above, there are a plurality of openings of the bypass, and at least one of the openings is provided outside the region affected by the flow velocity due to the protrusion.

The opening of the bypass is formed in a block provided on the inner wall of the intake passage corresponding to the lower end side of the sliding valve, or the plurality of openings are orthogonal to the intake direction. It can be configured to be arranged in the direction.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an enlarged view showing the vicinity of the opening of the main nozzle in the vaporizer of the present invention, (a)
Is a top view and (b) is a sectional view taken along line I-I of (a). The same components as those in the conventional example are designated by the same reference numerals, and different points will be mainly described.

Pilot jet 1 of carburetor body 101
A radially expanded void 121 is formed at the tip of 10, and the block 105 is provided with three bypass holes 122 communicating with the void 121. Figure 1
In (a), the flow direction of intake air is set to the direction of axis b,
When the direction orthogonal to this is the axis c, these three bypass holes 122 are arranged in a direction parallel to the axis c. The distance between the bypass holes 122 on both sides is wider than the width W of the opening protrusion 108.

The sliding valve 104 moves up slightly and the intake passage 10
When 2 opens slightly, the intake air vigorously passes under the slide valve 104. The part of the intake air that strikes the front of the opening protrusion 108 collides with the opening protrusion 108 and the momentum is killed. Conventionally, the bypass hole 111 is located at a position where the momentum is thus killed and a swirl flow is generated. Therefore, the negative pressure at the outlet of the bypass hole 111 does not increase, the ejection of fuel is poor, and the atomization is poor. . On the other hand, in the present invention, there are three bypass holes 122, and the two outermost holes are outside the opening protrusion 108, and the intake flow is not decelerated by the opening protrusion 108. Therefore, the negative pressure near the outlets of the two outer bypass holes 122 becomes large, and the atomized fuel of high quality is ejected from this, and the response response when accelerated at high speed can be improved.

According to the present invention, a plurality of bypass holes 122 are provided, and at least one of them is not affected by the flow velocity due to the opening protrusion 108. Therefore, a high quality atomized fuel from the bypass holes 122 is provided. Can be ejected, and the response response at the time of acceleration can be improved.

The diameter of the plurality of bypass holes 122 is 1
The diameter can be made smaller than the diameter of one bypass hole 111. In this embodiment, the areas of the three bypass holes 122 are combined to be the area of one conventional bypass hole. As a result, it is possible to promote the jetting and atomization of the fuel, which is scheduled to be supplied from the conventional bypass hole 111. However, the area is not limited to the same.

Regarding the arrangement of the plurality of bypass holes 122,
A place not affected by the flow velocity due to the opening protrusion 108,
That is, it is sufficient that the opening protrusion 108 does not reduce the flow velocity of the intake air. This is the opening protrusion 108.
There is no doubt that it is outside the width W of the bypass hole 122.
The position may be inside the width W as long as it is separated from the opening protrusion 108 in the direction of the axis b through which the intake air flows, or on the axis b if it is sufficiently separated.

FIG. 2 is a diagram showing a region affected by the flow velocity due to the opening protrusion 108. And the opening protrusion 1
When the width W of 08 is taken on the axis b, the width W is the base,
In the present invention, a range surrounded by an isosceles triangle having a height of 1.5 W is set as a region Z affected by the flow velocity by the opening protrusion 108. Then, at least one of the plurality of bypass holes 122 is arranged so as to be outside the region Z. In the embodiment of the present invention, the bypass holes 122, 122 on both sides are provided outside the area Z by being arranged outside the opening projection 108, but there is a certain distance from the opening projection 108. For example, even if the distance between the bypass holes 122 on both sides is smaller than the width of the opening protrusion 108, the bypass holes 122 can come out of the region Z.

In the embodiment of the present invention, the bypass hole 1
22 was drilled in block 105, but block 1
A configuration not using 05 is also possible, in which case it can be provided in the carburetor main body 101, that is, the inner wall of the intake passage 102.

Further, in the embodiment of the present invention, the cocoon type sliding valve has been described, but it is also applicable to a box type or round type sliding valve. That is, by forming a plurality of bypass holes 122,
At least one bypass hole may be located at a position where the influence of deceleration of intake air by the opening protrusion 108 is small.

[0026]

As described above, according to the present invention, the intake passage having the venturi portion formed in the carburetor body, the slide valve for changing the opening area of the intake passage in the venturi portion, and the slide valve are provided. On the intake passage wall, an opening protrusion protruding from the opening of the main nozzle, and a downstream side of the opening protrusion. In a sliding valve type carburetor having an opening bypass, there is a plurality of openings of the bypass, and at least one of the openings is provided outside the region affected by the flow velocity due to the opening protrusion. Therefore, even if the opening degree of the intake passage is small, the atomization of the fuel ejected from the bypass hole can be improved, and the response response at the time of acceleration from low speed to high speed is improved.

[Brief description of drawings]

FIG. 1 is an enlarged view showing the vicinity of an opening of a main nozzle in a vaporizer of the present invention, (a) is a top view,
(B) is an II sectional view of (a).

FIG. 2 is a diagram showing a region affected by a flow velocity due to an opening protrusion.

FIG. 3 is a diagram showing a configuration of a sliding valve type carburetor using a conventional cocoon type sliding valve.

4 is an enlarged view showing the vicinity of the opening of the main nozzle of FIG. 3, (a) is a top view, and (b) is a III-III sectional view of (a).

[Explanation of symbols]

100 vaporizer 101 vaporizer body 102 Intake passage 103 Venturi Club 104 sliding valve 105 blocks 106 Main nozzle 107 Main jet 108 Opening protrusion 109 jet needle 110 pilot jet 122 Bypass hole A intake direction Z Aperture area affected by flow velocity

Claims (3)

[Claims] 1. An intake passage having a venturi portion formed in a carburetor main body, a slide valve for changing an opening area of the intake passage in the venturi portion, a jet needle held by the slide valve, and the jet. A sliding valve having a main nozzle having an opening through which a needle is inserted in the intake passage wall, an opening protrusion protruding from the opening of the main nozzle, and a bypass opening downstream of the opening protrusion. A slide valve type carburetor, characterized in that there are a plurality of openings for the bypass, and at least one of the openings is provided outside the region affected by the flow velocity due to the opening projection. 2. The sliding valve type according to claim 1, wherein the opening of the bypass is formed in a block provided on an inner wall of the intake passage corresponding to a lower end side of the sliding valve. Vaporizer. 3. The plurality of openings are arranged in a direction orthogonal to the intake direction.
Or the sliding valve type carburetor according to the item 2.