JP2001073878A - Fuel control device for carburetor of rotary throttle valve type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary throttle valve type carburetor assuring a good operating characteristic of throttle valve and unlikely to generate rattles in a swivel installed on an operation lever. SOLUTION: A needle 17 is installed in a throttle valve 6 and interlocked in the rotating direction, and the tip is inserted into a fuel nozzle 9 approximately tightly, and at the side face of the nozzle 9, a nozzle hole 27 is provided whose section enlarges in the valve opening direction of the throttle valve, while the needle 17 is furnished with a slit 28 thinning upward, and the control of the fuel is conducted with the nozzle hole 27 and slit 28 by positioning the slit 28 identical to the nozzle hole 27. Thus the fuel control is made with rotation of the needle 17 interlocking with the throttle valve 6, and an operation lever 12 is hindered from varying vertically. It is arranged so that the fuel supply characteristics can easily be adapted to the requirements of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary throttle valve type carburetor often used for small engines.

[0002]

2. Description of the Related Art Conventionally, this type of carburetor has a throttle valve provided with a throttle hole corresponding to the intake passage orthogonal to an intake passage penetrating a carburetor body, and is rotatably arranged. Thus, the amount of air flowing through the intake passage is controlled by increasing or decreasing the matching area between the intake passage and the throttle hole. On the other hand, in order to smoothly operate the engine, it is necessary to increase or decrease the amount of fuel injected into the intake passage in accordance with the increase or decrease of the air amount.
No. 21562, the throttle valve is moved upward in accordance with the rotation of the throttle valve, and a needle attached to the throttle valve is moved within a fuel nozzle protruding from the throttle hole, and a fuel injection port is provided. The area of the fuel injection port is increased or decreased by moving the needle up and down in accordance with the rotation of the throttle valve, as described in JP-A-1-142255.

However, in the above-described conventional example, the structure for vertically moving the throttle valve and the needle with the rotation of the throttle valve becomes complicated, and the cost of the vaporizer increases. In addition, in the construction of Japanese Utility Model Publication No. 61-21562, the throttle lever of the throttle valve also moves up and down with the up and down movement of the throttle valve. The swivel engagement state is oblique. As a result, during the pulling operation of the cable wire, a vertical acting force is generated at the engaging portion between the cable wire and the swivel, so that the operability of the throttle valve is deteriorated and the swivel is more likely to rattle.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary throttle valve carburetor which has a simple structure, has good operability of a throttle valve, and does not cause looseness in a swivel mounted on an operation lever. As an issue.

[0005]

According to the present invention, a throttle valve chamber is provided orthogonal to an intake passage passing through a carburetor body, and a throttle valve having a throttle hole corresponding to the intake passage in the throttle valve chamber is provided. In a rotary throttle valve type carburetor rotatably arranged, a needle is attached to the throttle valve and linked in the rotation direction, and the tip is inserted almost densely into a fuel nozzle, and the throttle valve is opened on a side surface of the fuel nozzle. By providing a nozzle port having a cross section that increases in the direction, while providing a slit that tapers upward in the needle and aligning the slit with the nozzle port, fuel is controlled by the nozzle port and the slit. . Thus, fuel can be controlled by rotation of the needle linked to the throttle valve, and the structure of the carburetor can be simplified. In addition, since the throttle valve only rotates, the engagement state between the swivel of the operation lever and the cable wire does not become oblique, the operability of the throttle valve is improved, and the play of the swivel is reduced. Can be suppressed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described based on one embodiment of the present invention illustrated in the accompanying drawings. 1 to 3, reference numeral 1 denotes a rotary throttle valve type carburetor, and an intake passage 3 is provided through a body 2;
A cylindrical throttle valve chamber 4 is provided at right angles in the middle of the intake passage 3. The throttle valve chamber 4 rotatably accommodates a cylindrical throttle valve 6 having a throttle hole 5 aligned with the intake passage 3. The throttle valve 6 is biased in the closing direction and downward by a spring 8 disposed between the cover 7 closing the upper end of the throttle valve chamber 4 and the throttle valve 6. At the bottom of the throttle valve chamber 4, a fuel nozzle 9 stands upright on the rotation axis YY of the throttle valve 6. The base end of the fuel nozzle 9 is connected to a fuel chamber (not shown) via a main jet (not shown). At the bottom of the throttle valve 6, an insertion hole 10 for the fuel nozzle 9 is provided on the rotation axis YY, and the fuel nozzle 9 projects through the insertion hole 10 and into the throttle hole 5. An operation shaft 11 protruding upward from the upper part of the throttle valve 6 penetrates the cover 7, and an operation lever 12 is attached to an outer end. The operation lever 12 is provided with a swivel 13 for engaging a cable wire (not shown).

A needle chamber 15 is formed in the operation shaft 11, and a needle insertion hole 16 connected to the throttle hole 5 is provided at the bottom of the needle chamber 15. A needle 17 is provided in the needle chamber 15 so as to be interlocked with the rotation direction of the throttle valve 6.
The lower part of the needle 17 is projected from the needle insertion hole 16 to the throttle hole 5 and is inserted into the fuel nozzle 9 almost densely.

In order to attach the needle 17 to the throttle valve 6 so as to be interlocked with the rotation direction of the throttle valve 6, for example, as shown in FIG. Both ends of 19 are engaged with a guide groove 20 provided in the needle chamber 15 along the rotation axis YY of the throttle valve. Then, an adjusting screw 21 is screwed above the needle chamber 15, and the needle 17 is urged upward by a spring 22 disposed between the head 18 of the needle 17 and the bottom of the needle chamber 15, The needle head 18 is brought into contact with the adjusting screw 21. Thereby, the fine adjustment of the vertical position of the needle 17 can be performed by rotating the adjusting screw 21.

As another embodiment for interlocking the needle 17 with the throttle valve 6, as shown in FIG. 5A, the needle chamber 15 and the needle head 18 are traversed in place of the pin 19 of the above embodiment. The surface shape is a non-rotatable shape such as a square, or a protrusion 18a is provided on the side surface of the needle head 18 as shown in FIG.
It is also possible to engage with the groove 20 formed in. Further, as shown in FIG.
And the needle head 18 may be screwed into the needle chamber 15. In this case, the spring 22 acts as a lock for the needle 17.
Further, if the screwing of the needle head 18 to the needle chamber 15 is made firm, the spring 22 becomes unnecessary.

[0010] The fuel nozzle 9 is provided on the side face with the throttle valve 6.
Is provided with a nozzle port 27 having a base 26 descending in the valve opening direction. The needle 17 is formed in a hollow shape from the lower end to a predetermined position and has a slit 28 tapered upwardly on the side surface and connected to the hollow hole 30.
Are provided in the rotation axis direction. The fuel ejection amount is controlled by the bottom of the nozzle opening 27 and the tapered slit 28. Further, by selecting the shape of the descent of the bottom 26 of the nozzle port 27 and the shape of the slit 28, the fuel supply characteristics can be adapted to the requirements of the engine. The slit 28 may be formed at the lower end of the needle 17 as shown in FIG.

Further, the nozzle port 27 of the fuel nozzle 9
The bottom 26 is provided in a lowered state from the engine side of the fuel nozzle 9 to a position substantially orthogonal to the direction of the intake passage 3, and when the throttle valve 6 is in the idling opening position, FIG.
As shown in (a), the slit 28 of the needle 17 is located on the engine side of the fuel nozzle 9.
As shown in (b), the slit 28 of the needle 17 is located substantially orthogonal to the direction of the intake passage 3. That is, at the time of idling opening, the flow rate of the intake air passing through the fuel nozzle 9 becomes slow, so that the slit 28 is directed toward the engine side to increase the negative pressure acting on the slit 28. By making the slit 28 orthogonal to the passing intake air flow, the negative pressure acting on the slit is increased.

The operation lever 12 is provided with a hole 32 connected to the needle chamber 15 of the operation shaft 11 from the upper surface. The adjustment screw 21 is rotated from the hole 32 to adjust the relative position between the fuel nozzle 9 and the needle 17. Fine adjustment, that is, the slit 28 of the needle 17 and the nozzle port 2 of the fuel nozzle 9
7 can be finely adjusted. A plug 33 that normally closes the hole 32 is fitted to the operation lever 12 to prevent dust and rainwater from entering the needle chamber 15 and prevent air from leaking.

A seal member 34 for covering the operation shaft 11 is provided between the operation lever 12 and the cover 7.
Leakage of air from around this shaft and dust inside the vaporizer
Prevent rainwater from entering.

Next, the operation of the above configuration will be described. In a state where the operation lever 12 is not operated, the throttle valve 6 is held at an idling opening degree by the action of the spring 8, and the fuel injection port formed by the nozzle port 27 of the fuel nozzle 9 and the slit 28 of the needle 17 has a minimum opening. Is formed.

When the throttle valve 6 is turned to the open side against the spring 8, the matching area between the throttle hole 5 provided in the throttle valve 6 and the intake passage 3 increases, and the amount of air flowing through the intake passage 3 decreases. To increase. When the needle 17 rotates in synchronization with the rotation of the throttle valve 6, the alignment area between the bottom of the nozzle port 27 and the tapered slit 28 increases, and the opening area of the fuel injection port increases.

At the fully open position of the throttle valve 6, the throttle hole 5 of the throttle valve 6 and the intake passage 3 completely match, and the fuel formed by the nozzle port 27 of the fuel nozzle and the slit 28 of the needle 17 is formed. The nozzle has the maximum opening.

As shown in FIG. 8, a bleed hole 36 communicating the outside and the inside of the needle 17 is provided on the side surface of the needle 17 exposed to the throttle hole 5, so that air is injected into the fuel ejected from the fuel nozzle 9. It is possible to improve the atomization of the fuel by mixing.

[0018]

As described above in detail, according to the present invention, a needle is attached to the throttle valve and linked with the rotation direction, and the tip of the needle is inserted almost densely into the fuel nozzle. By providing a nozzle port whose cross section increases in the valve opening direction, while providing a tapered slit upward in the needle, and matching the slit with the nozzle port, the fuel is injected into the nozzle port and the slit. Is performed, the fuel can be controlled by the rotation of the needle linked to the throttle valve, and the structure of the carburetor can be simplified.

Further, since the opening area of the fuel injection port is controlled by the bottom of the nozzle port and the slit, fine control of the fuel can be performed by selecting the shape of the descent of the bottom of the nozzle port and the shape of the slit. Can be adapted to the requirements of the institution.

Further, since the throttle valve rotates only,
The engagement between the swivel of the operation lever and the cable wire does not become oblique, the operability of the throttle valve is improved, and the occurrence of backlash between the operation lever and the swivel can be suppressed, and the durability is improved. I do.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a throttle valve in a fully opened state according to an embodiment of the present invention.

FIG. 2 is a side view showing an engagement state between a fuel nozzle and a needle.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a cross-sectional view showing a positional relationship between a nozzle opening of a fuel nozzle and a slit of a needle when the throttle valve is idling and when it is fully opened.

FIG. 5 is a cross-sectional view of a main part showing another embodiment in which the needle chamber and the needle head are linked in the rotation direction.

FIG. 6 is a vertical sectional view of a main part showing another embodiment of a method for adjusting a needle.

FIG. 7 is a longitudinal sectional view of a main part showing another embodiment of the slit of the fuel nozzle.

FIG. 8 is a vertical sectional view of a main part showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary throttle valve type carburetor 3 Intake passage 5 Throttle hole 6 Throttle valve 9 Fuel nozzle 11 Operating shaft 12 Operating lever 17 Needle 26 Bottom of nozzle opening 27 Nozzle opening 28 Slit

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Satoshi Uno 5-10-10 Kotobukicho, Toyota City, Aichi Prefecture

Claims (3)

[Claims] 1. A rotary throttle valve wherein a throttle valve chamber is provided orthogonal to an intake passage penetrating a carburetor body, and a throttle valve having a throttle hole corresponding to the intake passage is rotatably disposed in the throttle valve chamber. In the carburetor, a needle is attached to the throttle valve so as to interlock with the rotation direction, and the tip of the needle is inserted almost densely into the fuel nozzle, so that a cross section of the side of the fuel nozzle increases in the opening direction of the throttle valve. A rotary throttle valve, characterized in that a nozzle port is provided, while the needle is provided with a tapered slit toward the upper side, and the slit is aligned with the nozzle port to control fuel at the nozzle port and the slit. A fuel control device for a carburetor. 2. The fuel injection system according to claim 1, wherein the nozzle port has a bottom that descends in a valve opening direction of the throttle valve, and the fuel ejection amount is controlled by the bottom and a tapered slit. Fuel control device for rotary throttle valve carburetor. 3. The nozzle opening of the fuel nozzle is provided from the engine side of the fuel nozzle to a position substantially orthogonal to the direction of the intake passage, and the slit faces the engine side when the throttle valve is at an idling opening. 3. The fuel control device for a rotary throttle valve carburetor according to claim 1, wherein when fully open, the fuel control device is directed to a position substantially orthogonal to the direction of the intake passage.