JPH07286560A - Operation limiting device for fuel adjusting needle valve of carburetor - Google Patents

Abstract

PURPOSE:To mount a regulating member on the head part of a fuel adjusting needle valve by weak force and prevent the regulating member-from being detached after attaching it. CONSTITUTION:An annular groove 33 is provided on the head part 32 of the fuel adjusting needle valve A of a carburetor. A cap 40 provided with a driver engaging groove 49 on its base end face is inserted outside the head part 32 of the fuel adjusting needle valve A slidably in the axial direction. The head part 32 of the fuel adjusting needle valve A and the cap 40 are respectively provided with serrations 34, 46 for obstructing relative rotation. A plurality of elastic claw pieces 44 holding the engaged condition of the serrations 34, 46 are provided on the circumferential wall of the center part in the axial direction of the cap 40. The extreme ends of the elastic claw pieces are elastically engaged with the annular groove 33 of the head part 32 of the fuel adjusting needle valve A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a vaporizer for a small internal combustion engine mounted on a portable working machine such as a mower or a power saw,
In particular, the present invention relates to an operation limiting device for a fuel adjusting needle valve in a carburetor that regulates the amount of fuel.

[0002]

2. Description of the Related Art In recent years, exhaust gas regulations have been established for portable work machines, and it is required that the amount of fuel falls within a predetermined range so that the driver does not deteriorate exhaust gas components even if he adjusts the fuel adjustment needle valve. To be done. The operation limiting device for the fuel adjusting needle valve in the carburetor disclosed in Japanese Patent Publication No. 236934 does not require special machining for the fuel adjusting needle valve, and the assembly of the regulating member is easy, which causes trouble to the engine. The fuel amount can be easily adjusted within the range that does not come.

As shown in FIG. 6, in the above-described fuel regulating needle valve operation limiting device, the regulating member 21 is attached to the fuel regulating needle valve A of the carburetor. The fuel adjusting needle valve A is mounted between the fuel passage 6 and the fuel passage 5 of the carburetor main body 2 which intersect each other. The fuel passage 5 opens to the bench lily portion of the intake passage 8 through the nozzle 7. The carburetor main body 2 is formed with a screw hole 4 and a cylindrical portion 3 coaxially with the fuel passage 5, an end of the cylindrical portion 3 is formed with a cylindrical wall 10, and the cylindrical wall 10 has a stop wall 9 protruding radially outward. Are integrally formed.

The fuel adjusting needle valve A is provided with a driver engaging groove 12 in a head portion 13 and a flange 14 in the middle thereof.
5 is screwed into the screw hole 4, and the tapered portion 16 at the tip is projected into the fuel passage 5. The passage area between the taper portion 16 and the fuel passage 5 is adjusted by the screwing of the fuel adjusting needle valve A, whereby the fuel amount in the idle operation of the engine is regulated. In order to prevent the fuel adjusting needle valve A from loosening, a spring 26 is interposed between the inner end surface of the cylindrical portion 3 and the flange 14. The regulating member 21 is a tubular body 25 formed by bending a leaf spring into a cylindrical shape.
Is elastically fitted onto the head portion 13 of the fuel adjusting needle valve A, the tubular body 25 is provided with a slit 22, and a split groove 23 for engaging a driver is formed at the end edge. The stop piece 24 that integrally projects with the tubular body 25 from the edge is folded back in parallel with the outer peripheral surface of the cylindrical wall 10.

Therefore, when the driver is engaged with the split groove 23 and the fuel adjusting needle valve A is rotated in the forward and reverse directions, the stop piece 24 hits the stop wall 9 as shown by a chain line to deteriorate the exhaust gas component. Limit the excessive adjustment of the appropriate fuel quantity. However, the above-mentioned restriction member 21 can be removed if the driver of the engine deliberately removes it, so that an excessive adjustment operation of the fuel adjustment needle valve A cannot be prevented, and if the restriction member 21 is attached again. , There is no evidence of whether excessive adjustment operations have been performed.

The fuel adjusting needle valve of the carburetor is delivered to the engine manufacturer after being adjusted by various test / inspection devices at the carburetor manufacturer, and the engine manufacturer re-adjusts the fuel adjusting needle valve based on the operation test of the engine. Or fine adjustment, and at this time, the regulating member is set on the head of the fuel adjusting needle valve, so in a mass-produced engine, the attaching of the regulating member to the head of the fuel adjusting needle valve of the carburetor is weak. Can be easily reached with
Moreover, a strong fall-off preventing force works, and it is required that the driver does not come off or damage even if the driver intentionally removes the regulating member.

[0007]

SUMMARY OF THE INVENTION In order to satisfy the above-mentioned requirements, an object of the present invention is to allow a restriction member to be attached to the head of a fuel adjusting needle valve with a weak force, and to prevent the restriction member from being removed after attachment. Another object of the present invention is to provide an operation limiting device for a fuel adjusting needle valve in a carburetor.

[0008]

In order to achieve the above object, the structure of the present invention has a cylindrical cap having a driver engaging groove on the base end surface of the head of a fuel adjusting needle valve of a carburetor. Directionally slidable externally, the head of the fuel adjusting needle valve and the cap are provided with engaging means for preventing relative rotation, and a plurality of elastic claw pieces for holding the engagement of the engaging means are provided at the axial center of the cap. It is provided on the peripheral wall of the portion, and the tip of the elastic claw piece is engaged with the annular groove of the head of the fuel adjusting needle valve.

[0009]

[Function] Since the cap as the regulating member is engaged with the head portion of the fuel adjusting needle valve in a serration manner, it can be mounted with a weak force.
The relative rotation of the cap is blocked.

The elastic claw piece of the cap elastically engages with the annular groove of the fuel adjusting needle valve to prevent the cap from falling off.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side sectional view showing a state before the operation limiting device according to the present invention is attached to a fuel adjusting needle valve of a carburetor,
FIG. 2 is a front view of the operation limiting device. Fuel adjustment needle valve A
Is screwed onto the wall portion of the carburetor main body 2, and the coil spring 26 is mounted between the head portion 32 of the fuel adjusting needle valve A and the wall portion of the carburetor main body 2. The carburetor body 2 is a stop piece 41 of the cap 40.
Is provided with a stop wall 9. The fuel adjusting needle valve A has a driver engaging groove 35 formed on the end surface of the head portion 32, a serration 34 formed on the outer peripheral surface of the head portion 32, and an annular groove 33 formed so as to cross the serration 34.
In the cross section of the annular groove 33, one side wall is tapered. In order to manufacture the fuel adjusting needle valve A, a tapered tip portion and a screw portion are sequentially turned on the peripheral surface of a bar material which has been previously processed for selenium, which is called a flat-rolled material.
4 is left and the annular groove 33 is turned to form the head 32, and finally the head 32 is cut off to form the engagement groove 35 on the end surface of the head.

On the other hand, the cap 40 as a restricting member has a cylindrical shape, and has a circular through hole 48 at the center of a base end wall (right end wall) 51 and a driver engagement groove 49 that crosses the through hole 48.
And a pair of crescent-shaped through holes 47 sandwiching the through hole 48. The tip (left end) of the cap 40 is integrally formed with a stop piece 41 projecting radially outward from the cylindrical portion 42 and capable of contacting the stop wall 9 of the carburetor main body 2. The cylindrical portion 42 has a pair of protrusions 43 formed on the inner peripheral surface thereof and projecting radially inward. A plurality of central portions of the cap 40 in the axial direction are provided (two in the illustrated embodiment).
One elastic claw piece 44 is formed symmetrically with respect to the axis. That is, the elastic claw piece 44 has the base portion 44a at the cylindrical portion 42a.
The distal end portion of the cap 40, which extends toward the base end of the cap 40, is separated from the cylindrical portion 42 by the U-shaped slit 45. The tip of the elastic claw piece 44 is curved inward slightly to the outside, and can be outwardly curved as shown by a chain line.
The cap 40 is integrally molded of synthetic resin, and the crescent-shaped through hole 4 is formed for the convenience of molding the elastic claw piece 44.
7 is provided on the end wall 51. A serration hole 46 is formed in the inner peripheral surface of the cylindrical portion 50 adjacent to the end wall 51 of the cap 40. The serration hole 46 is divided into two in the circumferential direction by the wall surface on the extension of the crescent-shaped through hole 47.

Next, the operation of the operation limiting device for the fuel adjusting needle valve in the carburetor according to the present invention will be described. A carburetor manufacturer measures the amount of fuel flowing through the fuel passage and rotates the fuel adjusting needle valve A by a driver engaged with the engagement groove 35 to set the fuel amount to an appropriate value. Therefore, as shown in FIG. 4, the cylindrical portion 42 of the cap 40 is externally inserted into the head portion 32 of the fuel adjusting needle valve A, and the protruding portion 43 is mounted so as to engage with the annular groove 33. At this time, the direction of the stop piece 41 of the cap 40 is set so that the normal and reverse rotation of the stop wall 9 can be obtained.

In the engine manufacturer, after mounting the carburetor on the engine, the driver operates the engine through the circular through hole 48 of the cap 40 while actually operating the engine and engages the engaging groove 3 of the fuel adjusting needle valve A.
5, the fuel adjustment needle valve A is rotated forward and backward, and the fuel amount is finely adjusted to an appropriate value. At this time, if the cap 40 is pressed by hand, the fuel adjusting needle valve A can rotate relative to the cap 40, and the direction of the stop piece 41 of the cap 40 does not change. When the cap 40 is strongly pushed into the head portion 32 of the fuel adjusting needle valve A when the proper amount of fuel is obtained, as shown in FIG. 5, the inner surface 51a of the base end wall 51 of the cap 40 is adjusted to the fuel adjusting needle valve A. When hitting the end face of the head 32, the serration hole 46 of the cap 40 meshes with the serration 34 of the head 32. Further, the pair of elastic claw pieces 44 elastically deforms radially outward (as indicated by the chain line in FIG. 1), and the tip of the elastic claw pieces 44 eventually becomes the annular groove 33 of the head portion 32 of the fuel adjusting needle valve A. The cap 40 cannot be pulled out.

In this state, the engaging groove 49 of the cap 40 is
When the driver is engaged, the fuel adjusting needle valve A can be rotated forward and backward within a predetermined range. When the fuel adjusting needle valve A exceeds the predetermined range, the stop piece 41 hits the stop wall 9 to prevent excessive adjustment of the fuel amount.

[0016]

As described above, according to the present invention, a cap having a driver engaging groove on the base end surface is axially slidably fitted over the head of the fuel adjusting needle valve of the carburetor to provide the fuel adjusting needle valve. Is provided with engaging means for preventing relative rotation between the head of the cap and the cap, and a plurality of elastic claw pieces for holding the engagement of the engaging means are provided on the peripheral wall at the axial center of the cap, and the head of the fuel adjusting needle valve is provided. Since the tip of the elastic claw piece is engaged with the annular groove of the portion, the cap as the restricting member can be attached to the head of the fuel adjusting needle valve with a weak force and cannot be removed after attachment.

If the driver intentionally removes the cap, the elastic claw pieces may be damaged, and evidence that the driver has performed an unreasonable operation remains.

Since the projecting portion projecting radially inward is formed at the root portion of the elastic claw piece of the cylindrical portion of the cap, the root portion is reinforced and at the time of delivery to the engine manufacturer, the projection of the cap is provided. Since it can be mounted so as to engage with the annular groove of the head of the fuel adjusting needle valve, there is no fear of loss, parts can be easily managed, and the engine manufacturer can finely adjust the fuel amount.

The elastic claw piece of the cap is located at the axial center of the cap, and both ends of the cap have a perfect cylindrical shape, so that the strength of the cap is not impaired and the elastic claw piece does not project outward. Therefore, the driver can be prevented from being intentionally destroyed.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a relationship between a fuel adjusting needle valve and a cap as an operation limiting device in a carburetor according to the present invention.

FIG. 2 is a front view of the cap.

3 is a front sectional view taken along the line 3A-3A in FIG.

FIG. 4 is a side sectional view showing a temporarily mounted state of the cap when delivered to the engine manufacturer.

FIG. 5 is a side cross-sectional view showing a completely mounted state of the cap.

FIG. 6 is a side sectional view of a conventional fuel regulator needle valve operation limiting device in a carburetor.

[Explanation of symbols]

A: Fuel adjustment needle valve 32: Head 33: Annular groove 34:
Serration 35: Engagement groove 40: Cap 41:
Stopping piece 42: Cylindrical part 43: Projection part 44: Elastic claw piece
46: Serration hole 47: Through hole 49: Engagement groove 5
0: Cylindrical part 51: Base wall

Claims (6)

[Claims] 1. A head cap of a fuel adjusting needle valve and a cap of a fuel adjusting needle valve of a carburetor, wherein a cylindrical cap having a driver engaging groove on a base end surface thereof is externally inserted so as to be slidable in an axial direction. An engaging means for preventing relative rotation is provided on the and, and a plurality of elastic claw pieces for retaining the engagement of the engaging means are provided on the circumferential wall at the central portion in the axial direction of the cap, and in the annular groove of the head of the fuel adjusting needle valve. An operation limiting device for a fuel adjusting needle valve in a carburetor, characterized in that the tips of elastic claw pieces are engaged. 2. The operation limiting device for a fuel adjusting needle valve in a carburetor according to claim 1, wherein the engaging means is a serration provided on the outer peripheral surface of the head of the fuel adjusting needle valve and the inner peripheral surface of the cap. . 3. The fuel regulating needle valve in a carburetor according to claim 1, wherein the annular groove in the head portion of the fuel regulating needle valve has a tapered side wall and traverses the serration of the head portion of the fuel regulating needle valve. Operation limiting device. 4. The operation limiting device for a fuel adjusting needle valve in a carburetor according to claim 1, wherein the fuel adjusting needle valve is formed by turning a flat grooved material. 5. The operation limiting device for a fuel adjusting needle valve in a carburetor according to claim 1, wherein a projection portion projecting radially inward is provided at a root portion of the elastic claw piece of the cylindrical portion of the cap. 6. The fuel regulating needle valve actuation limiting device in a carburetor according to claim 1, wherein the cap is made of a synthetic resin material.