JPH10220293A - Sliding throttle valve in sliding throttle valve-type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively increase negative pressure to act on a needle jet and a pilot outlet hole as well as to improve suction efficiency in the intermediate opening range of a sliding throttle valve. SOLUTION: A sliding throttle valve is provided with a facing side surface 1A on an air cleaner side and a facing side surface 1B on an engine side, and an inclined recessed part 1C is provided on the facing side surface 1A on the air cleaner side. The inclined recessed part 1C faces the facing side surface 1B on the engine side from the facing side surface 1A on the air cleaner side, is provided along the longitudinal axial line of the sliding throttle valve 1, and is symmetric with respect to the longitudinal axial line Y-Y of the intake passage 41, and the bottom part 1D nearest the facing side surface 1B on the engine side of the inclined recessed part 1C is on the longitudinal axial line Y-Y of the intake passage 41. Moreover, the distance L between the bottom part 1D and the facing side surface 1B on the engine side is gradually decreased from the upper part to the lower part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor for controlling the concentration and amount of an air-fuel mixture supplied to an engine. The present invention relates to a sliding throttle valve of a sliding throttle valve type carburetor that controls an opening area of an intake passage by mechanically operating an arranged sliding throttle valve.

[0002]

2. Description of the Related Art A conventional sliding throttle valve type carburetor is shown in FIG.
2 will be described. Reference numeral 40 denotes a carburetor main body in which an intake passage 41 is horizontally penetrated, and a throttle valve guide cylinder 42 is bored upward from an intermediate portion of the intake passage 41. The float chamber 45 is formed by disposing the float chamber main body 44 in the float chamber 45. In the float chamber 45, a constant fuel liquid level is formed by a float 46, a valve seat (not shown) and a float valve. A sliding throttle valve 47 is movably disposed in the throttle valve guide cylinder 42. The sliding throttle valve 47 is provided with a top T that closes an upper opening of the throttle valve guide cylinder 42 and a sliding throttle valve 47. Inner bottom 4
7A and the intake passage 41 by the spring S
And a jet needle 49 inserted into a needle jet 48 as a main fuel system that opens into the intake passage 41 passes through the lower bottom portion 47D of the sliding throttle valve 47. The vent needle portion V is formed by the lower bottom portion 47D and the intake passage 41 opposed thereto.

[0003] The sliding throttle valve 47 is a throttle valve guide cylinder 42.
12, an opposing side surface 47B on the air cleaner side facing the intake passage 41A on the side of the air cleaner A connected to the air cleaner A is formed on the right side of the slide throttle valve 47 in FIG. To the institution B connected to the institution B
The engine side facing side surface 47C facing the intake passage 41B on the engine side is formed.

A conventional throttle valve 47 will be described with reference to FIGS. The same structural parts are denoted by the same reference numerals as in FIG. FIG. 13 shows a sliding throttle valve 4.
7 is a simplified cross-sectional view in a cross section orthogonal to the sliding direction XX, and FIG. 14 is a simplified side view as viewed from the air cleaner A side. The sliding throttle valve 47 has a circular cross section, and the opposing side surface 47B on the air cleaner side is formed in an arc shape.

The needle jet 48 is immersed below the fixed fuel level in the float chamber 45 via the main fuel jet 50. Reference numeral 51 denotes an accelerator wire operated by a driver, one end of which is connected to an accelerator grip (not shown), and the other end of which is a locking member 5 screwed to the sliding throttle valve 47.
2 through an end 53. Reference numeral 54 denotes a pilot outlet hole as a low-speed fuel system which is opened in the intake passage 41 facing the lower end of the engine-side opposing side surface 47C of the sliding throttle valve 47. A mixture of fuel and air measured by an air jet is passed through the pilot outlet hole 54 to the intake passage 4.
1 is supplied.

[0006] When the driver operates the accelerator grip, the sliding throttle valve 47 is moved by the accelerator wire 51.
Is operated to control the opening and closing of the opening of the venturi portion V of the intake passage 41, and the air corresponding to the opening of the venturi portion V is moved from the intake passage 41A on the air cleaner side to the intake passage 41B on the engine side.
The main fuel and the low-speed fuel flow into the venturi section V through the needle jet 48 as the main fuel system and the pilot outlet hole 54 as the low-speed fuel system due to the negative pressure of the venturi section V generated by the air flow. And this fuel is supplied to the intake passage 41 on the engine side.
The operation of the engine is satisfied by being supplied to the engine B via B.

[0007]

In such a sliding throttle valve type carburetor, in the sliding throttle valve 47 in which the opposed side surface 47B on the air cleaner side is formed in an arc-shaped protruding surface, the intake passage 41A on the air cleaner A side. When the air flow (indicated by the dotted line in FIG. 13) flowing down along the longitudinal axis YY of the intake passage 41 collides with the opposed side surface 47B on the side of the arcuate air cleaner, the air flow Is the same angle as the inflow angle E of the airflow toward the collision point C on the opposite side of the extension of the line CD connecting the collision point C and the arc-shaped center D of the opposed side surface 47B on the air cleaner side. E, the air flow is diffused in a direction away from the longitudinal axis Y-Y of the intake passage 41, and the lower bottom portion 47D of the sliding throttle valve 47 is diffused.
It flows inside. That is, the airflow that collides with the opposed side surface 47B of the arcuate air cleaner side flows obliquely outward and downward on the arcuate surface, and converges in the direction of the inner peripheral wall 41C on the outer side of the intake passage 41 while sliding. 47 lower bottom 4
Flows into 7D. This state is shown by a dotted line in FIG.

On the other hand, the flow velocity of the air in the intake passage 41 having such a circular pipe shape is such that the flow velocity is large and the inertia is large in the central portion of the intake passage 41, but the inside of the intake passage 41 is located outside the intake passage 41. In the vicinity of the peripheral wall 41C, the air flow rate is small and the inertia is small, and the air flow flowing along the inner peripheral wall 41C on the outer side of the intake passage 41 causes a "peeling" phenomenon, and a vortex may occur in this portion. known.

Therefore, as described above, the air flow after colliding with the arc-shaped opposing side surface 47B on the air cleaner side is changed to the intake passage 4.
The fact that the air flow after the collision is directed toward the vortex is caused to converge toward the inner peripheral wall 41C on the outer side of 1.
According to this, the eddy current becomes a resistance to the airflow after the collision flowing into the lower bottom portion 47D of the sliding throttle valve 47, and air cannot be efficiently flowed into the lower bottom portion 47D of the sliding throttle valve 47. Having problems (poor inhalation efficiency).

Further, the inability to efficiently supply air into the lower bottom portion 47D of the sliding throttle valve 47 results in a sufficiently increased air flow velocity flowing through the venturi V formed by the lower bottom portion 47D and the intake passage 41. According to this, there is a problem that the negative pressure acting on the needle jet 48 and the pilot outlet hole 54 opening to the venturi portion V cannot be sufficiently increased.

In these conventional sliding throttle valves 47, the reduction of the suction efficiency and the reduction of the negative pressure acting on the needle jet 48 and the pilot outlet hole 54 are caused by the intermediate opening range of the sliding throttle valve 47. (A middle opening of the venturi portion V). That is, in the low opening range of the sliding throttle valve 47, the opening of the venturi portion V is minutely controlled, and the air flow flowing therethrough is almost in a vortex state. The difference due to the shape of the opposing side surface 47B does not have a great effect, and in the high opening range of the sliding throttle valve 47, the opening of the venturi portion V forms a large opening, and the opposing side surface 47B on the air cleaner side. Is substantially accommodated in the sliding throttle valve guide cylinder 42, so that the shape of the opposed side surface 47B of the sliding throttle valve 47 on the air cleaner side does not greatly differ.

[0012]

SUMMARY OF THE INVENTION A sliding throttle valve in a sliding throttle valve carburetor according to the present invention has been made in view of the above-mentioned problems. It is an object of the present invention to provide a sliding throttle valve carburetor that can further increase the negative pressure acting on the jet and pilot outlet holes.

[0013]

In order to achieve the above object, a sliding throttle valve in a sliding throttle valve type carburetor according to the present invention is provided with a throttle valve guide cylinder connected to one side from an intake passage. In a sliding throttle valve type carburetor in which a sliding throttle valve for controlling opening and closing of an intake path is movably arranged in a throttle valve guide cylinder, the sliding throttle valve is disposed on an engine side facing an engine side intake path. An air cleaner side facing the intake path on the air cleaner side, and an inclined recess formed in the longitudinal direction of the sliding throttle valve and recessed in the air cleaner side facing side. The air flow passing through the intake path on the air cleaner side and colliding with the opposing side surface on the air cleaner side is reduced by the inclined recess.
The first feature is that the light source is directed obliquely downward toward the approximate center of the bottom.

Further, according to the present invention, the inclined recess formed on the opposed side surface on the air cleaner side extends from the opposed side surface on the air cleaner side to the opposed side surface on the engine side and along the longitudinal axis of the sliding throttle valve. The inclined recess is symmetrical on both sides of the longitudinal axis of the intake path, and the bottom of the inclined recess closest to the engine-side facing side is on the longitudinal axis of the intake path, Further, a second feature is that the distance between the bottom portion and the opposing side surface on the engine side is sequentially reduced from above to below.

Further, the present invention is characterized in that, in addition to the second feature, the cross-sectional shape of the inclined recess is formed by a single curved portion.

The present invention has a fourth feature in that, in addition to the second feature, the cross-sectional shape of the inclined recess is formed by a straight portion.

Further, in the present invention, in addition to the second feature, a fifth feature is that the cross-sectional shape of the inclined recess is formed by a curved portion and a straight portion.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sliding throttle valve type carburetor according to the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a sliding throttle type vaporizer including a sliding throttle valve, and FIG.
FIG. 3 is a right side view as viewed from the right side of FIG. 1, FIG. 4 is a vertical sectional view of a sliding throttle valve used in the sliding throttle valve carburetor of FIG. 1, and FIG. FIG. 6 is a right side view of the sliding throttle valve of FIG. 4 as viewed from the right side. The same components as those in FIG. 12 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 1 denotes a sliding throttle valve movably disposed in the throttle valve guide cylinder 42, and a sliding direction XX of the sliding throttle valve 1 (a sliding throttle when disposed in the throttle valve guide cylinder 42). In a cross section (corresponding to the top plan view shown in FIG. 5) perpendicular to the direction of movement of the valve 1),
Engine side facing side 1B facing engine B and air cleaner A
And the opposing side surface 1A on the air cleaner side facing the air cleaner. Here, facing the engine B refers to the side facing the engine B, and more specifically refers to the left side portion in FIG. Further, facing the air cleaner A means a side facing the air cleaner A, and more specifically, a right side portion in FIG. In this example, the opposing side surface 1B on the engine side was formed in an arc shape, and the opposing side surface 1A on the air cleaner side was formed in a straight line shape.

The opposite side surface 1 on the air cleaner side
A is provided with an inclined concave portion 1C. The inclined recess 1C will be described in detail with reference to FIGS. 4, 5 and 6, and the inclined recess 1C satisfies the following requirements. (1) The inclined concave portion 1C is located on the opposing side surface 1A on the air cleaner side, and the opposing side surface 1B on the engine side is shifted from the opposing side surface 1A on the air cleaner side.
Are formed along the longitudinal axis GG of the sliding throttle valve 1. (2) The inclined recess 1C
The intake passage 41 has a symmetrical shape on both sides J and K of the longitudinal axis YY (in other words, it corresponds to the center of the cross section of the sliding throttle valve) of the intake passage 41, and the opposite side 1B of the inclined recess 1C closest to the engine. 1D near the longitudinal axis Y-
It is located on or near Y. (3) The distance L between the bottom 1D of the inclined recess 1C, the opposing side surface 1B on the engine side, and the distance L decreases gradually from above to below. In this example,
The cross-sectional shape of the inclined concave portion 1C was formed by a single curve having a radius R starting from the line YY. The inner bottom portion 1E of the sliding throttle valve 1 is provided with a female screw hole 1G for screwing the locking member 52 toward the lower bottom portion 1F and a jet needle insertion hole 1H. The lower bottom portion 1F serves as a cutterway formed from the bottom portion 1J of the engine side facing side surface 1B toward the air cleaner side facing side surface 1A.

The sliding throttle valve 1 having the above structure is movably disposed in the sliding throttle valve guide cylinder 42 of the carburetor body 40. According to this, the bottom portion 1 below the sliding throttle valve 1 is provided.
A venturi portion V is formed by F and the intake passage 41 opposed thereto, and the jet needle 49 is inserted into a needle jet 48 as a main fuel system that opens to the venturi portion V in the intake passage 41, and further, the engine side A bottom portion 1J below the opposed side surface 1B is provided with a pilot outlet hole 54 serving as a low-speed fuel system that opens into the intake passage 41.
Oppose. In addition, the intake passage 41 is controlled by a sliding throttle valve 1 to an intake passage 41A on the air cleaner side and an intake passage 41B on the engine side.
The opposed side surface 1A of the sliding throttle valve 1 on the air cleaner side is open to the intake passage 41A on the air cleaner side, and the opposed side surface 1B on the engine side is open to the intake passage 41 on the engine side.
Opening facing B.

When the intake passage 41B on the engine side of the sliding throttle valve type carburetor is connected to the engine B and the intake passage 41A on the air cleaner side is connected to the air cleaner A, the driver operates the accelerator wire. The sliding throttle valve 1 controls the opening of the intake passage 41 (the opening of the venturi V) accordingly.

According to the sliding throttle valve type vaporizer using the sliding throttle valve according to the present invention, the nozzle negative pressure applied to the needle jet 48 and the pilot outlet hole negative pressure applied to the pilot outlet hole 54 are particularly slid. Throttle valve 1
In the intermediate opening range of 大 き く, it was possible to greatly increase as compared with the conventional sliding throttle valve. As described above, the negative pressure of the nozzle of the needle jet 48 and the negative pressure of the pilot outlet hole 54 are significantly increased especially in the intermediate opening range of the sliding throttle valve 1 as compared with the conventional sliding throttle valve using the conventional sliding throttle valve. It is probable that this was done for the following reasons.
That is, the inside of the intake passage 41A on the air cleaner side is
The air flow flowing down along one longitudinal axis Y-Y is
When the air flow collides with the arc-shaped surface of the inclined recessed portion 1C formed in the opposed side surface 1A of the sliding throttle valve 1 on the air cleaner side, the air flow approaches the longitudinal axis Y-Y of the intake passage 41, or in other words, slides. The air flow is converged toward the center of the opposing side surface 1A of the dynamic throttle valve 1 on the air cleaner side. That is, the inclined recess 1C
The airflow that has collided with the airflow flows obliquely inward on the surface of the inclined recess 1 </ b> C, and is converged on the central portion of the intake passage 41.

On the other hand, the airflow that has collided with the surface of the inclined recess 1C flows with a strong flow velocity obliquely downward along the inclined recess 1C toward the bottom 1F below the sliding throttle valve 1. This is because the distance L between the bottom 1D of the inclined recess 1C and the opposing side surface 1B on the engine side is gradually reduced from above to below. This is best illustrated by the dotted arrow in FIG.

As described above, the opposing side surface 1 on the air cleaner side is used.
The airflow after the collision with A is converged on the central portion of the intake passage 41. And converging into substantially the center of the lower bottom portion 1F of the sliding throttle valve 1. Can reliably direct the air flow toward an air flow having a large flow velocity flowing through the central portion of the intake passage 41 and a large inertia. According to this, the air flow after the collision is extremely smoothly slid. It can flow into substantially the center of the lower bottom 1F of the valve 1 and
And a large amount of air can be supplied into the venturi portion V formed by the intake air passage 41 and the air intake passage 41. That is, the air flow after colliding with the opposing side surface 1A on the air cleaner side is less affected by the vortex generated near the inner peripheral wall 41C outside the intake passage 41. As described above, the fact that a large amount of air can be supplied into the venturi portion V means that the flow velocity of the air flowing through the venturi portion V can be increased. Jet 4
8. Negative pressure generated in the pilot outlet hole 54 can be increased.

As described above, the fact that the amount of air flowing through the venturi portion V can be increased means that the intake efficiency of the air supplied to the engine B can be increased, and the output of the engine can be reduced with a small intake path diameter. It has been improved. The needle jet 4 in the intermediate opening range of the sliding throttle valve 1 is also provided.
8. The fact that the negative pressure generated in the pilot outlet hole 54 was able to be increased,
This makes it possible to improve the atomization characteristics of the fuel sucked into the engine, thereby greatly improving the transient characteristics of the engine and the operability in the intermediate opening range. Furthermore, in the setting operation of the vaporizer, the degree of freedom on the side of increasing the amount of fuel can be increased, so that the setting operation is facilitated.
(If the negative pressure acting on the needle jet 48 is small,
Even if the diameter of the fuel jet is large, the fuel cannot be sucked into the intake passage, and the degree of freedom toward the fuel increasing side is small.) The cross-sectional shapes of the opposed side surface 1A on the air cleaner side and the opposed side surface 1B on the engine side are as described above. Not limited, oval shape,
It may be a short shape or a composite shape thereof.

The inclined concave portion 1C formed on the opposed side surface 1A of the sliding throttle valve 1 on the air cleaner side described in the above embodiment has a single curved portion (formed by a curve having a single radius). According to this, the inclined concave portion 1C can be easily manufactured and its dimensional accuracy can be improved.

Next, another embodiment of the inclined concave portion 1C formed on the opposed side surface 1A of the sliding throttle valve 1 on the air cleaner side will be described below. In the following embodiment, the inclined concave portion 1C is formed with a linear portion, and the inclined concave portion 1C shown in FIG. 7 has a conical shape. The inclined concave portion 1 shown in FIG.
C has a truncated cone shape. The inclined concave portion 1C shown in FIG. 9 has a composite conical shape.

FIGS. 10 and 11 show the inclined recess 1C.
Another embodiment is shown, in which these inclined recesses 1C are shown.
Was formed by connecting a straight portion and a curved portion.

The selection of the inclined recessed portion 1C on the side surface 1B of the sliding throttle valve 1 on the air cleaner side is performed in consideration of the convergence of the air flow from the intake passage 41A on the air cleaner side toward the center of the venturi V. Selected.

[0030]

In the sliding throttle valve of the sliding throttle valve type carburetor according to the present invention, a throttle valve guide cylinder is continuously provided to one side from the intake passage, and the throttle valve guide cylinder is provided with an intake passage. In a squeezing throttle valve type carburetor in which a sliding throttle valve for controlling the opening and closing of a valve is movably arranged, the sliding throttle valve is provided on the engine side facing the engine side intake path and on the air cleaner side intake path. An air cleaner side facing the air cleaner side; and an inclined recess formed in the opposite side surface on the air cleaner side and formed along the longitudinal axis direction of the sliding throttle valve. The air flowing in the intake passage on the air cleaner side collides with the inclined concave part of the sliding throttle valve, because the air flow colliding with the opposite side surface on the side is directed obliquely downward toward the approximate center of the bottom by the inclined concave part. Then, the airflow is at the bottom below the center of the sliding throttle valve. Be more positively directed toward, Komu flows toward the atmospheric consisting airflow inertia increases flow velocity in the central portion of the intake passage. Thus, the amount of air flowing through the venturi section can be increased, and the air suction efficiency can be improved, whereby the output of the engine can be improved. On the other hand, the fact that a large amount of air was able to flow through the venturi portion enabled the air flow speed flowing through the venturi portion to be increased, and the negative pressure acting on the needle jet and pilot outlet holes to be increased. The fuel atomization characteristics in the intermediate opening range of the valve can be improved, the transient characteristics and operability of the engine can be greatly improved, and the degree of freedom of fuel increase in the intermediate opening range is increased, and the carburetor This significantly improved the setting workability. Further, when forming the inclined concave portion of the sliding throttle valve, particularly when the inclined concave portion is formed in an arc shape with a single radius R, the inclined concave portion can be manufactured accurately and easily by lathe processing. This is effective in reducing the manufacturing cost of the container.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a sliding throttle valve type carburetor using a sliding throttle valve according to the present invention.

FIG. 2 is a cross-sectional view taken along line ZZ in FIG.

FIG. 3 is a right side view of FIG. 1;

FIG. 4 is a longitudinal sectional view of a sliding throttle valve used in the sliding throttle valve carburetor of FIG. 1;

FIG. 5 is an upper plan view of the sliding throttle valve of FIG. 4;

FIG. 6 is a right side view of the sliding throttle valve of FIG. 4;

FIG. 7 is a cross-sectional view showing another embodiment of the inclined recess of the sliding throttle valve of the present invention.

FIG. 8 is a cross-sectional view showing another embodiment of the inclined concave portion of the sliding throttle valve of the present invention.

FIG. 9 is a cross-sectional view showing another embodiment of the inclined concave portion of the sliding throttle valve of the present invention.

FIG. 10 is a transverse sectional view showing another embodiment of the inclined recess of the sliding throttle valve of the present invention.

FIG. 11 is a cross-sectional view showing still another embodiment of the inclined concave portion of the sliding throttle valve of the present invention.

FIG. 12 is a longitudinal sectional view showing a sliding throttle valve of a conventional sliding throttle valve type carburetor.

FIG. 13 is a simplified cross-sectional view of the sliding throttle valve of FIG.

FIG. 14 is a simplified right side view of the sliding throttle valve of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sliding throttle valve 1A Opposite side surface on air cleaner side 1B Opposite side surface on engine side 1C Inclined recess 1D Bottom 1F Lower bottom 41 Intake path 41A Intake path on air cleaner side

Claims (5)

[Claims] 1. A sliding throttle in which a throttle valve guide cylinder is continuously provided toward one side from an intake path, and a sliding throttle valve for controlling opening and closing of the intake path is movably disposed on the throttle valve guide cylinder. In the valve type carburetor, the sliding throttle valve 1 includes an engine side facing side surface 1B facing the engine side intake passage 41B, and an air cleaner side intake passage 4B.
The air cleaner includes an opposed side surface 1A facing the air cleaner facing the air cleaner 1A, and an inclined recess 1C formed in the opposed side surface 1A on the air cleaner side and formed along the longitudinal axis direction GG of the sliding throttle valve 1. Throttle valve carburetor which directs the air flow passing through the intake passage 41A on the side and colliding with the opposed side surface 1A on the air cleaner side obliquely downward toward the approximate center of the bottom 1F by the inclined recess 1C. Sliding throttle valve in. 2. The inclined recessed portion 1C recessed in the opposed side surface 1A on the air cleaner side is directed from the opposed side surface 1A on the air cleaner side to the opposed side surface 1B on the engine side and the longitudinal axis X of the sliding throttle valve 1. -X, the inclined recess is symmetrical on both sides J and K of the longitudinal axis Y-Y of the intake passage 41, and is closest to the engine-side facing side surface 1B of the inclined recess 1C. The bottom 1D is located on the longitudinal axis Y-Y of the intake passage 41, and further, the distance L between the bottom 1D and the opposing side surface 1B on the engine side is gradually reduced from above to below. A sliding throttle valve in the sliding throttle valve type carburetor described in the above. 3. The sliding throttle valve of a sliding throttle valve carburetor according to claim 2, wherein the cross section of the inclined recessed portion 1C is formed by a single curved portion. 4. The sliding throttle valve of a sliding throttle valve carburetor according to claim 2, wherein the cross-sectional shape of the inclined recessed portion 1C is formed by a straight portion. 5. The sliding throttle valve of a sliding throttle valve type carburetor according to claim 2, wherein the cross-sectional shape of the inclined concave portion 1C is formed by a curved portion and a straight portion.