JP2000186621A - Fuel regulating valve in carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fuel regulating valve of a carburetor from being manipulated freely by the driver of an engine after the fuel regulating valve of the carburetor is adjusted at the time of shipping from a factory. SOLUTION: A screw hole 25a and a fuel passage hole 23a having a smaller diameter than the screw hole 25a which sequentially extend inward are arranged coaxially in a carburetor body 20, and a screw shaft part 4 screwed around the screw hole 25a and an end needle part 3 fitted to the fuel passage hole 23a are arranged on the fuel regulating valve 2 sequentially from a head part 7 to an end, so that the area of the fuel passage hole 23a is regulated by the end needle part 3. A cylindrical part 29a having larger diameter than the head part 7 of the fuel regulating valve 2 is arranged in the carburetor body 20. An axial projected groove 14 is arranged in the peripheral surface of an operation limiting cover 10 which is serration-fitted on the head part 7 of the fuel regulating valve 2 and is engaged with an axial limitation groove 30 arranged in the inner circumferential surface of the cylindrical part 29b leaving a clearance inbetween. A recess 61 for engaging a special tool is arranged in the end wall 10a of the operation limiting cover 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel regulating valve for a carburetor of a small internal combustion engine mainly mounted on a power saw, a brush cutter and the like.

[0002]

2. Description of the Related Art Even in a small internal combustion engine, the fuel flow rate is adjusted in advance in a manufacturing plant in accordance with the tightening of exhaust gas regulations, and it is difficult for a driver to directly operate a fuel adjustment valve of a carburetor to adjust the fuel flow rate. Is required. Accordingly, in an operating environment of an engine such as a high altitude where the atmospheric pressure is low, the operating region in which the exhaust gas component of the engine is deteriorated is avoided by restricting the operating region of the throttle valve operating lever without operating the fuel adjustment valve. It is necessary to take such measures.

For example, in a fuel control valve in a carburetor disclosed in Japanese Patent Application Laid-Open No. 6-102093, an operation restricting lid is provided on the head of the fuel control valve in order to prevent the fuel control valve from turning in the fuel increasing direction. Is attached. However, when the operation restricting lid is attached to the head of the fuel adjustment valve, the rotation position of the fuel adjustment valve may be out of order, although the coil spring for suppressing the movement of the fuel adjustment valve is mounted. Also, with the above-described fuel adjustment valve, the driver can directly operate the fuel adjustment valve of the carburetor to adjust the fuel flow rate to some extent.
Does not conform to the above emission regulations.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to prevent a driver of an engine from arbitrarily operating a fuel regulating valve of a carburetor after factory adjustment.
It is to provide a fuel regulating valve in a carburetor.

[0005]

In order to solve the above-mentioned problems, according to the structure of the present invention, a screw hole extending inward and a fuel passage hole having a smaller diameter than the screw hole are coaxially provided in the carburetor body.
The fuel regulating valve is provided with a screw shaft portion screwed into the screw hole in order from the head to the tip and a tip needle portion fitted into the fuel passage hole, and the area of the fuel passage hole is adjusted by the tip needle portion. In the fuel regulating valve in the carburetor, a cylindrical portion having a larger diameter than the head of the fuel regulating valve is provided in the carburetor body, and an axial restriction groove provided on an inner peripheral surface of the cylindrical portion is provided.
An axial ridge provided on the outer peripheral surface of the operation limiting lid fitted with the serration to the head of the fuel regulating valve is engaged with a gap, and a special tool is engaged with the end wall of the operation limiting lid. It is characterized by having a recess.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, at the time of shipment from a factory, after adjusting a fuel adjusting valve of a carburetor according to operating conditions of an engine, an operation limiting lid is fitted to a head of the fuel adjusting valve, and a fuel adjusting valve is provided. Is embedded in the carburetor body, so that the driver cannot operate it from outside without permission. However, it is necessary for the sales / repair company to adjust the fuel flow rate according to the environment of the region where the engine is operated. -Allow the repair shop to operate the fuel regulating valve using special tools. That is, while providing a specially shaped recess in the end wall of the operation limiting lid, a tool instead of the conventional driver, that is, a pin or the like protruding from a plate connected to the end of the operating shaft is engaged with the recess to adjust the fuel. Rotate the valve. Even in this case, the amount of rotation or the amount of operation of the fuel regulating valve is determined by the clearance (circumferential dimension) between the axial ridge on the outer peripheral surface of the operation restricting lid and the groove of the cylindrical portion adjacent to the screw hole of the carburetor body. Is limited to

[0007]

FIG. 1 is a left side sectional view showing a mounted state of a fuel adjusting valve in a carburetor according to the present invention, and FIG. 2 is a front view thereof. As shown in FIG. 1, a carburetor body 20 has a suction passage 21 extending in a direction perpendicular to the plane of the drawing at a center portion, and a fuel chamber 24 formed at a lower end wall, and a through hole connecting the fuel chamber 24 and the suction passage 21. A fuel nozzle 40 is attached to 22. The fuel nozzle 40 is provided with an annular groove 43 and a radial passage 42 on the peripheral wall of the cup-shaped main body, and a valve body 41 formed of a known disk is disposed at the upper end of the main body, and is locked at the upper end of the main body. The retaining ring 40a having a plurality of leg pieces is configured so that the valve body 41 does not come out upward.

The fuel regulating valve 2 is screwed and supported in a screw hole 25 a orthogonal to the through hole 22. The carburetor body 20 is provided with a stepped cylindrical portion 2 on the projecting wall portion 20a projecting sideways in order from the outer end to the inner side.
9, a screw hole 25a, a fuel passage hole 25, and a small-diameter fuel passage hole 23a are formed coaxially. The tip needle portion 3 of the fuel regulating valve 2 is projected into the fuel passage hole 23a, and the passage 23 orthogonal to the fuel passage hole 25 from the fuel chamber 24, the fuel passage hole 2
5. The flow rate of fuel supplied to the intake passage 21 via a sleeve 51, a fuel passage hole 23a, an annular groove 43, and a passage 42, which will be described later, is adjusted. A plurality of positioning pins 26 are integrally formed on the lower wall surface of the vaporizer main body 20 and fitted into positioning holes (not shown) of the lower wall plate. The fuel chamber 24 is defined by a diaphragm sandwiched between the carburetor body 20 and the above-described lower wall plate. However, such a configuration is well known and is not directly related to the gist of the present invention and will not be described further.

The stepped cylindrical portion 29 has a small-diameter cylindrical portion 29a inside the step portion 28 and a large-diameter cylindrical portion 29 outside the step portion 28.
b, a step-stop ring 9 to be described later abuts on the step portion 28, and an operation limiting cover for restricting the adjusting operation of the head 7 and the fuel adjusting valve 2 on the large-diameter cylindrical portion 29b. 10 are accommodated. The fuel regulating valve 2 has a flange 6 and a serration shaft 7b formed on a head 7, and a groove 7a for engaging a tool is formed on an end face of the head 7.

The cup-shaped operation limiting lid 10 has a cylindrical portion 12 into which the flange 6 is fitted, and a serration hole 13 into which the serration shaft 7b is fitted. 61 are formed. The inner peripheral wall of the large-diameter cylindrical portion 29b has a groove width of the side wall 30a and the side wall 30b.
An axial restriction groove 30 defined by (see FIG. 2) is formed, and a metal holding plate 19 is fitted and fixed to the opening end wall of the large-diameter cylindrical portion 29b.

As shown in FIG. 2 with a lattice pattern, the substantially elliptical holding plate 19 has two circular openings 19a through which the operation restricting lid 10 can be inserted.
9a is provided with a notch 19b at the edge. The width (circumferential dimension) of the notch 19b is substantially equal to the ridge 14 of the operation restricting lid 10, and the holding plate 19 partially covers the end of the restricting groove 30 of the large-diameter cylindrical portion 29b. A recess 31 having the same outer shape as the holding plate 19 is formed at the opening edge of the large-diameter cylindrical portion 29b so that the holding plate 19 does not protrude from the protruding wall portion 20a. The holding plate 19 is firmly fitted in the recess 31 so that it cannot be easily removed.

The fuel control valve 2 is composed of a high-speed fuel control valve and a low-speed fuel control valve arranged side by side, and has a large-diameter cylindrical portion 29b for accommodating the operation restricting lid 10 mounted on each fuel control valve 2.
Are connected to each other at the peripheral wall portions. Accordingly, the detent ring 9 made of a relatively soft synthetic resin is also integrated, and is provided with two through holes 9a without screw grooves. The through holes 9a are press-fitted into the small-diameter cylindrical portion 29a and the large-diameter cylindrical portion 29b of the vaporizer body 20.

As shown in FIG. 1, the head 7 of the fuel regulating valve 2
A screw hole 25a extending inward in the carburetor body 20 and a fuel passage having a smaller diameter than the screw hole 25a so that the fuel flow rate does not change when the operation restricting lid 10 is mounted on the carburetor or due to vibration of the engine. While the hole 23a is provided coaxially, the screw shaft part 4 which is screwed into the screw hole 25a in order from the head 7 to the tip of the fuel regulating valve 2 and the tip needle part 3 which fits into the fuel passage hole 23a.
Are provided on the inner peripheral surface of the fuel passage hole 23a.
Is provided.

Actually, the fuel passage hole 23a is formed for convenience of processing.
A cylindrical portion 55 having a larger diameter than the fuel passage hole 23a.
And a sleeve 51 having a fuel passage hole having substantially the same diameter as the fuel passage hole 23a is fitted into the cylindrical portion 55, and the sleeve 51
From the upstream side to the downstream side of the fuel flow (sleeve 5).
1 from the base end to the distal end).

The fuel regulating valve 2 is assembled as follows. First, after the sleeve 51 is press-fitted into the cylindrical portion 55, a tool is engaged with the groove 7a of the head 7 of the fuel control valve 2, and the screw shaft portion 4 of the fuel control valve 2 is inserted into the screw hole 25a of the carburetor body 20. At the same time, the large-diameter screw shaft portion 5 is screwed into the through hole 9a of the detent ring 9 while cutting a screw groove. At the same time, by adjusting the length (axial dimension) of the distal needle portion 3 of the fuel adjusting valve 2 fitted to the sleeve 51 while measuring the fuel flow rate, the flow adjusting groove 53 and the distal needle portion 3 are connected. The cross-sectional area (passage area) of the gap between them, that is, the fuel flow rate is adjusted. Finally, the serration hole 13 of the operation restricting lid 10 is fitted to the serration shaft 7b of the head 7 of the fuel adjusting valve 2 so that the fuel adjusting valve 2 cannot be loosened (rotated in the fuel increasing direction).

The operation limiting lid 10 is connected to the opening 19 a of the holding plate 19.
When it is pushed into the inside of the large-diameter cylindrical portion 29b, the ridge 14 of the operation restricting lid 10 is engaged with the restriction groove 30 of the large-diameter cylindrical portion 29b through the notch 19b of the holding plate 19. Operation restriction lid 10
At the time of mounting, the friction of the threaded portion of the large diameter screw shaft portion 5 of the fuel adjusting valve 2 with the through hole 9a of the detent ring 9 and the sleeve 5
The friction of the fitting portion of the distal end needle portion 3 with respect to 1 prevents the fuel adjustment valve 2 from rotating. Since the operation restricting lid 10 is inserted into the large-diameter cylindrical portion 29b and does not protrude to the outside from the projecting wall portion 20a, it is difficult to forcibly remove the operation restricting lid 10.

As shown in FIGS. 1 and 2, it is preferable that the operation restricting lid 10 is mounted such that it is sufficiently pulled into the inside from the protruding wall portion 20a. According to the present invention, two pin holes 61 are provided in the end wall 10 a of the operation limiting lid 10. The pin hole 61 may penetrate the end wall 10a or may be a recess that does not penetrate the end wall 10a. As shown in FIG. 3, the tool 70 has two axial pins 7 on the outer surface of the meniscus 72 connected to the tip of the operating shaft 73, with respect to the pin hole 61 provided in the end wall 10 a.
1 are combined. Although not shown, a handle similar to a normal driver is connected to the base end of the operation shaft 73.

When the sales / repair company adjusts the fuel adjusting valve 2, the two pins 71 of the tool 70 are inserted into the pin holes 61 of the end wall 10a of the operation limiting lid 10 and, for example, in the direction of the arrow x in FIG. When the tool 70 is rotated, the protruding ridge 14 of the operation restricting lid 10 is changed from the state shown in FIG. 2 to the wide restricting groove 30 provided on the inner peripheral surface of the cylindrical portion 29 b covered by the holding plate 19.
It rotates inside. However, the amount of rotation of the operation restriction lid 10 is within a range until the ridge 14 hits the side wall 30b of the restriction groove 30, and the operation restriction lid 10 cannot be further rotated. When the fuel regulating valve 2 is rotated in the direction of the arrow x, the tip needle portion 3 protrudes inward of the sleeve 51, so that the passage 23, the fuel passage hole 25, and the sleeve 5 extend from the fuel chamber 24.
1. The flow rate of fuel sucked into the intake passage 21 through the fuel passage hole 23a and the valve body 41 is reduced. The fuel regulating valve 2 shown in FIG. 2 is at the position of the maximum fuel flow rate, and the fuel regulating valve 2 cannot be adjusted in the direction in which the fuel flow rate increases.

In the embodiment shown in FIG. 4, a projection wall 62 having a crescent cross section is formed integrally with the upper half of the end wall 10a of the operation restricting lid 10, and a single pin hole 64 is formed in the end wall 10a. Provided. The tool 70 is formed by joining a meniscus 72 having a flat peripheral wall surface 72a formed by removing a part of a disc to an end of an operation shaft 73 and projecting an axial pin 74 from the outer surface of the meniscus 72. You. To operate the operation restriction lid 10, the pin 74
Is inserted into the pin hole 64 of the operation restricting lid 10, the meniscus 72 is overlapped on the outer surface of the end wall 10a, and the peripheral wall surface 72a is
Abuts on the flat surface 63. Thereby, the tool 70 is integrally engaged with the operation restricting lid 10, and the operation restricting lid 10 can be rotated by the operation shaft 73.

In the embodiment shown in FIG. 5, the end wall 10a of the operation restricting lid 10 has a flat peripheral wall 66a and an arc-shaped peripheral wall 6a.
6b are provided. The recess 66 may penetrate the end wall 10a.
On the other hand, the tool 70 is formed by connecting a meniscus 72 whose outer shape matches the recess 66 to the end of the operation shaft 73. Tool 7
0 meniscus 72, peripheral wall surface 72a is recessed 66, peripheral wall surface 6
6a and the peripheral wall surface 62b engages with the peripheral wall surface 66b so that the operation limiting lid 10 can be rotated by the operation shaft 73.

The present invention can be applied not only to a rotary throttle valve carburetor but also to a butterfly throttle valve carburetor.

[0022]

As described above, according to the present invention, a screw hole extending inward in the carburetor body and a fuel passage hole having a smaller diameter than the screw hole are provided coaxially, and the fuel regulating valve is provided from the head to the tip. A fuel adjusting valve in a carburetor having a screw shaft portion screwed into the screw hole and a tip needle portion fitted to the fuel passage hole in order to adjust the area of the fuel passage hole by the tip needle portion; In the carburetor main body, a cylindrical portion having a larger diameter than the head of the fuel control valve is provided, and a serration fitting is fitted to the head of the fuel control valve in an axial restriction groove provided on the inner peripheral surface of the cylindrical portion. An axial ridge provided on the outer peripheral surface of the operation restricting lid is engaged with a gap, and a recess for engaging a special tool is provided on an end wall of the operation restricting lid. The rotation of the operation limiting lid is performed using a special tool having a pin or a protruding piece to be engaged. Because it's, it is not possible to adjust the driver arbitrarily fuel flow rate of institutions that do not have a special tool.

The construction is simpler than conventional ones such as filling the mounting portion of the operation-restriction lid with an adhesive or covering with a stopper, and only a sales / repair company having special tools is required for repair / inspection. Since the fuel control valve can be operated quickly, maintenance and management are easy, and exhaust gas regulations can be complied with.

[Brief description of the drawings]

FIG. 1 is a left side sectional view showing a fuel regulating valve in a carburetor according to the present invention.

FIG. 2 is a front view showing a main part of the fuel adjustment valve.

FIG. 3 is a perspective view showing a relationship between an operation restricting lid externally fitted to the fuel adjustment valve and a special tool.

FIG. 4 is a perspective view showing a relationship between an operation restriction lid and a special tool according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a relation between an operation limiting lid and a special tool according to a third embodiment of the present invention.

[Explanation of symbols]

2: Fuel adjustment valve 3: Tip needle part 4: Screw shaft part
5: Large-diameter screw shaft 7: Head 7b: Serration shaft 9: Detent ring 10: Operation limiting lid 10a: End wall 1
2: cylindrical part 13: serration hole 14: ridge 1
9: holding plate 19a: opening 19b: notch 20: carburetor body 21: intake passage 23a: fuel passage hole 24:
Fuel chamber 25: Fuel passage hole 25a: Screw hole 29: Stepped cylindrical portion 29a: Small diameter cylindrical portion 29b: Large diameter cylindrical portion
30: Restriction groove 30a, 30b: Side wall 31: Recess 4
0: fuel nozzle 40a: retaining ring 41: valve body 43:
Annular groove 51: Sleeve 53: Flow rate adjusting groove 55: Cylindrical part 61: Pin hole 62: Projecting wall 63: Flat surface 64:
Pin hole 66: hollow 66a: peripheral wall surface 66b: peripheral wall surface 70: tool 71: pin 72: meniscus 72a:
Peripheral wall 72b: Peripheral wall 73: Operation axis 74: Pin

Claims (4)

[Claims] 1. A screw hole extending inward in the carburetor body and a fuel passage hole having a smaller diameter than the screw hole are coaxially provided, and the fuel adjusting valve is screwed into the screw hole in order from the head to the tip. A fuel adjustment valve in a carburetor having a screw shaft portion and a tip needle portion fitted to the fuel passage hole, and having the tip needle portion adjust the area of the fuel passage hole.
A cylinder having a larger diameter than the head of the fuel control valve is provided in the carburetor main body, and an operation restriction in which a serration is fitted to the head of the fuel control valve in an axial restriction groove provided in an inner peripheral surface of the cylinder. An axial ridge provided on the outer peripheral surface of the lid is engaged with a gap, and a recess for engaging a special tool is provided on an end wall of the operation limiting lid. Fuel regulating valve. 2. A fuel regulating valve in a carburetor according to claim 1, wherein said recess is a plurality of axial pin holes. 3. A fuel regulating valve in a carburetor according to claim 1, wherein one pin hole and a crescent-shaped projecting wall are provided in an end wall of said operation restricting lid. 4. The fuel regulating valve according to claim 1, wherein the depression is a half-moon-shaped depression.