JPH09329059A - Sliding throttle valve type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the control of the working and assembling accuracy of the mixture jet and jet needle of a carburetor by integrating its fuel systems into one simple system, stably supplying fuel at a proper air-fuel ratio, and under a smaller opening degree of its sliding throttle valve reducing a fluctuation in the intake air flow to the lift level, of the sliding throttle valve as well as reducing the intake negative pressure acting on its fuel injection port. SOLUTION: A pressure-controlled chamber 24 controlled under a negative pressure as not causing air compression mixes air and fuel together to obtain a mixture of a fixed air-fuel ratio which is then mixed with air metered in a sliding throttle valve 5. When the sliding throttle valve 5 is opened only by a predetermined opening degree or below, only a main intake throttle port 10 formed at the lower part of a side wall 6a of the throttle valve 5 on the intake upstream side controls the opening area of an intake passage 3 as well as an auxiliary throttle port 11 formed on the downward side to a fuel injection port 21 reduces the intake negative pressure acting on the fuel injection port, to thereby prevent the mixture flow from being sensitively affected by the accuracy of a mixture jet 22 and a jet needle 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding throttle valve type carburetor equipped with a sliding throttle valve which advances and retreats into an intake passage to control the opening and closing of the intake passage.

[0002]

2. Description of the Related Art Generally, a carburetor has a small intake flow rate due to the compressibility of air when the negative pressure in the intake pipe is large such as idling, resulting in a rich air-fuel ratio. As described above, when the intake pipe negative pressure becomes small, the air-fuel ratio becomes thin and the fuel becomes insufficient. Therefore, it is necessary to separately provide a fuel control system such as a low speed system and a power system.

[0003]

However, when the carburetor is made multi-system like this, the air-fuel ratio control becomes complicated, and the breathing is caused because the connection of each fuel system does not work well at the time of vehicle start and sudden acceleration. Riding comfort problems such as occurrence will occur.

Further, a sliding throttle valve for advancing and retracting into the main intake passage to control opening and closing of the main intake passage is provided, and a jet needle interlocking with the throttle valve is inserted into the needle jet, and the sliding throttle valve sucks intake air. There is a sliding throttle valve type carburetor that controls the supply fuel from idling operation to full open operation by changing the area of the gap formed between the jet part of the needle jet and the needle, while controlling the amount. This is also because air as a compressible fluid is controlled by a sliding throttle valve and fuel as an incompressible fluid is controlled by a jet needle.The effect of air compression cannot be avoided, and the air-fuel ratio is kept constant over the entire operating range. Is difficult to do.

Further, in the above-mentioned sliding throttle valve type carburetor, since the change of intake air with respect to the lift amount becomes large in the low opening range of the throttle valve, when the fuel is changed in accordance with the change amount of the intake air. The taper angle of the jet needle becomes large, and it is necessary to control the processing accuracy of the jet needle and the air-fuel mixture jet combined therewith and the assembly accuracy thereof to a very high level, which is extremely difficult in manufacturing.

An object of the present invention is to provide a sliding throttle valve type carburetor which can make the fuel system into a single system having a simple structure and can stably supply the fuel at an appropriate air-fuel ratio. .

[0007]

According to the present invention, a groove is formed in an intake passage wall into which a lower end of a side wall of a sliding throttle valve is inserted at a predetermined opening or less, and a lower portion of an intake upstream side wall of the sliding throttle valve is provided. When the opening is equal to or less than the predetermined opening, a main intake throttle opening that forms the narrowest portion of the intake passage is provided, and when the opening is equal to or less than the predetermined opening, the main intake throttle opening is formed on the lower portion of the side wall on the intake downstream side of the sliding throttle valve. Provide an auxiliary throttle opening that has a larger area than the intake throttle opening. A fuel injection port is provided in the intake passage between the main intake throttle port and the auxiliary throttle port, or directly below them, and a mixture jet is connected to the fuel injection port. A fuel jet is installed upstream. A control pressure chamber is formed between the mixture jet and the fuel jet,
An air introduction passage provided with an air jet is connected to the control pressure chamber.

Then, the negative pressure in the control pressure chamber is controlled by the air-fuel mixture jet and the air jet to a negative pressure of a magnitude at which air compression does not occur, so that the air is introduced from the air introduction passage and the fuel metering jet into the control pressure chamber. The air and fuel are always proportional to each other, and the air-fuel ratio of the air-fuel mixture generated in this control pressure chamber is constant in all rotation regions. On the other hand, the amount of air flowing through the main intake passage is regulated by the sliding throttle valve and mixed with the air-fuel mixture ejected from the fuel injection port, but the air-fuel mixture in the control pressure chamber has a large volume ratio of air. Therefore, it has the same compressibility as air. Therefore, the air flowing through the main intake passage and the air-fuel mixture supplied from the fuel injection port are always proportional to each other, and the air-fuel ratio supplied to the engine is constant over the entire rotation range.

When the sliding throttle valve is below a predetermined opening,
Only the main intake throttle opening and the auxiliary throttle opening are opened, and the opening area of the intake passage is controlled by the main intake throttle opening.
As a result, the amount of change in the intake air amount with respect to the lift amount of the sliding throttle valve is reduced, and the taper angle of the jet needle can be reduced. Further, the intake negative pressure acting on the fuel injection port is reduced by the auxiliary throttle port, and it is possible to prevent the accuracy of the air-fuel mixture jet and the jet needle from excessively affecting the air-fuel mixture flow rate. Therefore, it becomes easy to control the processing accuracy of the air-fuel mixture jet and the jet needle and the assembly accuracy thereof.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a groove into which a lower end of a peripheral wall of a sliding throttle valve is inserted at a predetermined opening or less is provided in an intake passage wall, and the predetermined portion is provided at a lower part of an intake upstream side peripheral wall of the sliding throttle valve. When the opening is less than or equal to the opening, a main intake throttle opening that forms the narrowest part of the intake passage is provided, and when the opening is less than or equal to the predetermined opening, the main intake throttle is formed in the lower part of the peripheral wall on the intake downstream side of the sliding throttle valve. An auxiliary throttle opening that is opened in a larger area than the mouth is provided, and a fuel jet opening is opened between the main intake throttle opening and the auxiliary throttle opening or immediately below them, and a mixture jet connected to the fuel jet opening. A control pressure chamber is provided between the mixture jet and a fuel jet provided upstream of the fuel flow, and an air introduction passage provided with an air jet is connected to the control pressure chamber.

The main intake throttle opening and the auxiliary throttle opening are formed by a notch groove provided upward from the lower end of the peripheral wall. The main intake throttle opening and the auxiliary throttle opening can be formed by a plurality of holes.

Further, due to the shape of the notch groove forming the main intake throttle opening and the auxiliary throttle opening, the amount of increase of air with respect to the rise of the sliding throttle valve and the amount of increase of the air-fuel mixture due to the gap between the jet needle and the air-fuel mixture jet. Can be proportional. Further, when the main intake throttle opening and the auxiliary throttle opening are formed by a plurality of holes, it is possible to make the air amount and the air-fuel mixture amount ejected from the fuel injection port proportional by the hole diameter or the arrangement of the holes.

[0013]

1 and 2, reference numeral 1 denotes a sliding throttle valve type carburetor, a main intake passage 3 of which penetrates a body 2, and a throttle valve guide cylinder 4 crosses the main intake passage 3. It is provided. A sliding throttle valve 5 that directly controls the engine output is inserted into the guide cylinder 4 so as to be able to move back and forth. The side wall 6 of this sliding throttle valve 5 is a bottom wall 7
A main intake throttle opening 10 is provided on the upstream side of the intake air, and an auxiliary throttle opening 11 having a larger area than the main intake throttle opening 10 is provided on the downstream side of the intake air. . The main intake throttle opening 10 and the auxiliary throttle opening 11 are notched grooves 1 provided upward from the lower end of the extending portion 8.
3 and 14, but a plurality of holes 15 and 16 provided in the extending portion 8 as shown in FIG.
It is also possible to form by. The sliding throttle valve 5
A groove 18 is formed on the bottom surface of the lower intake passage 3 so as to correspond to the side wall 6 of the sliding throttle valve 5, and the sliding throttle valve 5 extends into the groove 18 from a fully closed state to a predetermined opening degree. The lower part of the part 8 is inserted. Therefore, in this opening range, only the main intake throttle opening 10 and the auxiliary throttle opening 11 are opened, and the main intake throttle opening 10 forms the narrowest portion 19 of the main intake passage 3.
1, the auxiliary narrowing portion 20 having a larger area than the narrowest portion 19
Is formed. The main intake throttle opening 10 and the auxiliary throttle opening 1
The notch grooves 13 and 14 forming 1 have a predetermined opening or less,
In order to moderate the increase and decrease of the air amount with respect to the vertical movement of the sliding throttle valve 5, the groove height L and the groove width W are expressed by the formula L / W ≧ 1.
It is formed so as to satisfy (desirably L / W ≧ 1.5).

On the other hand, on the wall surface of the main intake passage 3 below the sliding throttle valve 6, between the upstream side wall 6a and the downstream side wall 6b of the sliding throttle valve 5 (including the side wall 6a or 6b). The fuel injection port 21 is opened. Further, no fuel injection port is provided upstream of the sliding throttle valve 6 including the others. An air-fuel mixture measuring jet 22 is connected to the injection port 21 on the upstream side of the fuel flow, and a fuel measuring jet 23 is provided below it. The mixture jet 22
Between the fuel metering jet 23 and the fuel metering jet 23
The control pressure chamber 24 is connected to an air introduction passage 25 which communicates the other with the atmosphere or an intake downstream of an air cleaner (not shown). The air introduction passage 25 is provided with an air metering jet 26. The fuel metering jet 2
The lower part of 3 is communicated with the oil surface of the float chamber 27.
The fuel in the float chamber 27 is formed on a constant oil level by a float mechanism including a float 28 and a needle valve 29. This float mechanism has a general structure which has been conventionally used.

A jet needle 31 is attached to the bottom wall 7 of the sliding throttle valve 5. This jet needle 3
The tip side of 1 is inserted into the air-fuel mixture measuring jet 22 and the fuel measuring jet 23, and the fuel flowing into the control pressure chamber 24 is measured by the gap formed between the jet needle 31 and the fuel measuring jet 23. In addition, the air-fuel mixture generated in the control pressure chamber 24 is jet needle 31.
And is jetted into the main intake passage 3 by the gap formed between the air-fuel mixture measuring jet 22 and the air-fuel mixture measuring jet 22.

The negative pressure in the control pressure chamber 24 is controlled by the gap between the air-fuel mixture jet 22 and the jet needle 31 and the air jet 26, and this negative pressure acts on the fuel injection port 21 during idling or deceleration. 60mmHg that does not cause air compression even when the negative pressure is highest
As described below, the throttle area of the air measuring jet 26 is set to be larger than the area of the gap between the mixture measuring jet 22 and the jet needle 31. Therefore, in the control pressure chamber 24, the amounts of air and fuel are proportionally mixed, and the air-fuel ratio A / F is always constant.

Further, the air-fuel mixture generated in the control pressure chamber 24 is measured in the gap between the air-fuel mixture measuring jet 21 and the jet needle 31 and ejected into the main intake passage 3 to open the sliding throttle valve 5 at a predetermined opening. If it is less than a certain degree, it is mixed with the main intake throttle port 10, and if it is more than a predetermined opening degree, it is mixed with the air measured between the lower end of the throttle valve and the wall surface of the intake passage. Since both the air flowing through the intake passage 3 and the air flowing through the intake passage 3 are compressed fluids, the air-fuel ratio A / F of the air-fuel mixture supplied to the engine is constant over the entire operating range.

Next, the operation of the above embodiment will be described. From the fully closed state of the sliding throttle valve 5 to a predetermined opening, the sliding throttle valve 5 is
The lower part of the extended portion 8 is inserted into the groove 18 so that only the main intake throttle opening 10 and the auxiliary throttle opening 11 are opened. Therefore, in this opening degree range, the air flowing through the main intake passage 3 is controlled by the main intake throttle opening 10, the amount of air is gradually increased and decreased, and the auxiliary throttle opening 11 causes the fuel injection port 2
The intake negative pressure acting on 1 is reduced. Then, this negative intake pressure is introduced into the control pressure chamber 24 through the gap between the fuel injection port 21, the air-fuel mixture jet 22 and the jet needle 31. The negative pressure of the control pressure chamber 24 is adjusted by the gap between the mixture measuring jet 22 and the jet needle 31 and the area ratio of the air measuring jet 26, and is controlled to 60 mmHg or less at which air is not compressed. Therefore, from the air introduction passage 25 and the fuel metering jet 23 to the control pressure chamber 2
The amount of air sucked into No. 4 is always proportional to the amount of fuel, and the air-fuel ratio A / F of the air-fuel mixture generated in the control pressure chamber 24 is constant.

Further, the air-fuel mixture in the control pressure chamber 24 is ejected into the main intake passage 3 through the gap between the air-fuel mixture jet 22 and the jet needle 31, and is mixed with the air introduced from the main intake throttle opening 10. In this case, since the air-fuel mixture in the control pressure chamber 24 has a large volume ratio of air, it is a compressed fluid similar to air, and is ejected from the fuel injection port 21 and the amount of air measured by the main intake throttle port 10. The mixture volume is always proportional,
The air-fuel ratio A / F supplied to the engine becomes constant.

When the sliding throttle valve 5 has a predetermined opening or more, the extended portion 8 below the sliding throttle valve 5 comes out of the groove 18 to open the main intake passage 3, and a large amount of air is supplied. As described above, both the air controlled by the sliding throttle valve and the air-fuel mixture generated in the control pressure chamber 24 are compressible fluids, and the amount of air measured by the sliding throttle valve and the fuel injection port 21 The amount of air-fuel mixture ejected is always proportional, and the air-fuel ratio A /
F becomes constant.

FIG. 3 shows the shapes of the notch grooves 13 and 14 forming the main intake throttle opening 10 and the auxiliary throttle opening 11, respectively.
The amount of increase of air with respect to the rise of the sliding throttle valve 5 is arbitrarily changed at a predetermined opening or less. In this example,
The notch grooves 13 and 14 are formed so that the width becomes smaller upward.

In FIG. 5, a correction valve 37 capable of adjusting the amount of air automatically or manually is provided in the air introduction passage 25,
In this embodiment, the negative pressure of the control pressure chamber 24 is adjusted to correct the mixing ratio A / F. In this case, the air introduction passage 2
Although it is possible to provide only the correction valve 37 on the No. 5, if the upstream side of the air introduction passage 25 is branched and the fixed jet 38 is provided on one side and the correction valve 37 is provided on the other side as shown in FIG. The correction range of the correction valve 37 can be regulated, and this range can be finely adjusted.

FIG. 6 shows an example in which an idle passage 35 having one side connected to the control pressure chamber 24 and the other side connected to the main intake passage 3 downstream of the sliding throttle valve 5 is provided. With this configuration, fuel can be supplied during idling operation from the dedicated idle passage 35, and idling operation can be stabilized.

[0024]

As described in detail above, according to the present invention, air and fuel are mixed in a control pressure chamber controlled to a negative pressure of a magnitude that does not cause air compression, and an air-fuel mixture with a constant air-fuel ratio is obtained. By mixing this air-fuel mixture with the air metered by the sliding throttle valve, the air-fuel ratio supplied to the engine can be kept constant in the entire operating range, so that the fuel system can be controlled by one system and the cost can be reduced. In addition to being able to reduce the amount, it is possible to prevent breathing when the vehicle starts or when accelerating suddenly.

Further, when the sliding throttle valve is at a predetermined opening or less, the opening area of the intake passage is controlled only by the main intake throttle port formed in the lower portion of the intake upstream side wall of the sliding throttle valve, and the sliding passage is controlled. Since the change amount of the intake air amount with respect to the lift amount of the throttle valve is made small, the taper angle of the jet needle for controlling the air-fuel mixture amount and the fuel amount can be correspondingly made small. Further, since the intake negative pressure acting on the fuel injection port is reduced by the auxiliary throttle port, it is possible to prevent the accuracy of the air-fuel mixture jet and the jet needle from sensitively affecting the air-fuel mixture flow rate. Therefore, it becomes easy to control the processing accuracy of the air-fuel mixture jet and the jet needle and the assembly accuracy thereof.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a sliding throttle valve type carburetor of the present invention.

FIG. 2 is a view on arrow A in FIG.

FIG. 3 is a principal part explanatory view showing another embodiment of the shapes of the main intake throttle opening and the auxiliary throttle opening of the present invention.

FIG. 4 is an explanatory view of essential parts showing an embodiment of another method of forming the main intake throttle opening and the auxiliary throttle opening according to the present invention.

FIG. 5 is a main part explanatory view showing an embodiment in which a correction valve is provided in the air introduction passage in the present invention.

FIG. 6 is an explanatory view of essential parts showing an example in which an idling passage is provided independently in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sliding throttle valve type vaporizer 3 Main intake passage 5 Sliding throttle valve 10 Main intake throttle port 11 Auxiliary throttle port 21 Fuel injection port 22 Mixture metering jet 23 Fuel metering jet 24 Control pressure chamber 26 Air metering jet 31 Jet needle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Sato 5-10, Kotobukicho, Toyota-shi, Aichi Takei Vaporizer Co., Ltd.

Claims (1)

[Claims] 1. A sliding throttle valve that advances and retreats into the intake passage to control opening and closing of the intake passage, and a sliding throttle valve that is provided on a wall of the intake passage below the sliding throttle valve and has a predetermined opening degree or less. A groove into which the lower end of the side wall is inserted, a main intake throttle port provided in the lower part of the intake upstream side wall of the sliding throttle valve, which forms the narrowest part of the intake passage when the opening is less than a predetermined value, and the sliding throttle. An auxiliary throttle opening that is provided in the lower part of the side wall on the intake downstream side of the valve and is opened to a larger area than the main intake throttle opening when the opening is less than a predetermined opening, between the main intake throttle opening and the auxiliary throttle opening, or these A fuel jet opening directly below, a mixture jet connected to the fuel jet, a fuel jet provided upstream of the fuel flow of the mixture jet, and a control pressure formed between the mixture jet and the fuel jet. Chamber, an air introduction passage connected to the control pressure chamber, and the air introduction passage An air jet provided in the passage,
A jet needle that is interlocked with the sliding throttle valve and is inserted into the air-fuel mixture jet and the fuel jet with a gap, and the control pressure chamber is controlled to a negative pressure below a predetermined value by the air-fuel mixture jet and the air jet. A sliding throttle valve type carburetor characterized in that