JP2001214808A - Low speed mixture adjusting device for carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable adjusting a pilot screw by a tool generally on the market, and to mechanically restrict the adjusting width thereof. SOLUTION: An adjusted groove P6 is provided on a rear end surface P5 of a pilot screw P. A restricting member 6 comprises an operating hole 6C facing to the adjusted groove P6 of the rear end surface P5 of the pilot screw P and penetrating from a rear end surface 6A to an tip end surface 6B of the restricting member 6, and an abutting portion 6D arranged on the tip end surface 6B of the restricting member 6 and abutting on the rear end surface P5 of the pilot screw P when the pilot screw P moves so as to make a space S small. On the rear end surface P5 of the pilot screw P, the tip end surface 6B of the restricting member 6 is fixed at a specified space S.

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 air-fuel mixture supplied to an engine, and more particularly to adjusting and controlling the concentration of low-speed air-fuel mixture during low-speed operation including idling operation of the engine. The present invention relates to a low-speed air-fuel mixture adjusting device for a carburetor having a pilot screw, and an idle limiter for limiting the adjustment of the pilot screw.

[0002]

2. Description of the Related Art In a low-speed air-fuel mixture adjusting device for a carburetor having a pilot screw, the adjustment of the pilot screw by a driver is limited to a certain range. This is to prevent the low-speed mixture from becoming a rich mixture above a certain concentration even when the driver operates the pilot screw unnecessarily (called an idle limiter). It suppresses the emission of certain carbon monoxide (CO). FIG. 2 shows a first example of a conventional low-speed air-fuel mixture device of a carburetor having an idle limiter. Reference numeral 1 denotes a carburetor body through which an intake passage 2 penetrates, and a low-speed mixture formed by a low-speed fuel jet and a low-speed air jet (both not shown) passes through the low-speed mixture passage 3 into the intake passage 2. Open to
Reference numeral 4 denotes a pilot screw hole, and a pilot hole 4A, a female screw hole 4B, and an insertion hole 4C are continuously provided from the front end to the rear end,
The distal end of the lower hole 4A is connected to the low-speed mixture passage 3, and the insertion hole 4
The rear end of C opens at the boss end 1A of the vaporizer main body 1. P
Denotes a pilot screw, which has a tapered needle valve portion P1, a shaft portion P2, a male screw portion P3, and a flange portion P from the front end to the rear end.
4 are continuously provided, and a rear end face P5 of the flange portion P4 has a minus groove,
An adjustment groove P6 such as a plus groove is formed. The pilot screw P is screwed into the pilot screw hole 4, the tapered needle valve portion P1 is inserted into the low-speed mixture passage 3, the male screw portion P3 is screwed into the female screw hole 4B, and the flange portion is formed. P4 is arranged in the insertion hole 4C. And
A flat screwdriver (not shown) is fitted into the adjustment groove P6 of the pilot screw P to
To adjust the low-speed mixture concentration. That is, when the screw portion is a right-handed screw, when the flathead screwdriver is rotated clockwise, the effective opening area of the low-speed mixture passage 3 is reduced, and the low-speed mixture concentration is controlled to be thin. The effective opening area can be increased, and the low-speed air-fuel mixture concentration can be set high. Therefore, by rotating the minus screwdriver, the appropriate position of the pilot screw P can be selected, and the effective opening area of the appropriate low-speed air-fuel mixture passage 3 is set, whereby a desired low-speed air-fuel mixture concentration can be obtained. After the adjustment of the pilot screw P, the insertion hole 4C opening at the boss end 1A of the pilot screw hole 4 is closed with the blind plug 5. According to the above, after the adjustment of the pilot screw P, any adjustment to the pilot screw P is prevented.

[0003] Another conventional example will be described with reference to FIG.
The same components are denoted by the same reference numerals, and different portions will be described. The outer shape of the flange P4 at the rear end of the pilot screw P is D-cut P7. That is, a part of the outer shape of the circular flange P4 is cut straight. This is best illustrated in FIG. Further, the inner diameter of the insertion hole 4C opened to the boss end 1A is made larger than that of the insertion hole of FIG. The screwing of the pilot screw P is adjusted by inserting a box-shaped driver having a hole shape corresponding to the D-cut P7 into the insertion hole 4C and fitting it into the D-cut P7.

[0004]

According to the first example of the prior art, it is impossible to adjust the pilot screw P at all after shipment from the vaporizer production factory. No. According to the second conventional example, if a special tool such as the box-type screwdriver described above is prepared, the adjustment can be performed after shipment, but the adjustment range cannot be limited, and the low-speed mixture is abnormal. It cannot be prevented from becoming too dark.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. Even after shipment from a factory, the concentration of the low-speed air-fuel mixture can be adjusted by using a general commercially available tool, and the adjustment range is mechanically limited, so that the low-speed air-fuel mixture is mechanically limited. It is an object of the present invention to provide a low-speed air-fuel mixture adjustment device for a carburetor in which the air-fuel mixture concentration is prevented from increasing significantly.

[0006]

In order to achieve the above object, a low-speed air-fuel mixture adjusting device for a carburetor according to the present invention is screwed to a carburetor main body, has a tapered needle valve at the tip, and has a longitudinal axis. Low speed mixing of a carburetor with a pilot screw that variably controls the effective opening area of the low speed mixture passage by screwing in the direction and adjusts the low speed mixture concentration flowing from the low speed mixture passage to the intake path of the carburetor In the air conditioner,
An adjustment groove is provided on the rear end face of the pilot screw and the front end face of the restricting member is fixedly arranged at a constant gap on the rear end face of the pilot screw. And an abutting portion that abuts on the rear end surface of the pilot screw when the pilot screw moves at a constant distance so as to reduce the gap, at the operation hole penetrating from the front end surface to the front end surface. It is characterized by having.

[0007]

The adjustment of the pilot screw is performed by fitting a commercially available flathead screwdriver into the adjustment groove of the pilot screw through the operation hole of the control member and rotating it. When the pilot screw is rotated greatly, the rear end surface of the pilot screw comes into contact with the contact portion on the front end surface of the control member, and thereafter, the rotation of the pilot screw is mechanically prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a low-speed gas mixture device for a vaporizer according to the present invention will be described below with reference to FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals. The insertion hole 4C of the pilot screw hole 4 opens at the boss end 1A of the vaporizer main body 1. A flange P4 is formed at the rear end of the pilot screw P, and adjustment grooves P6 such as a minus groove and a plus groove are formed in the rear end face P5 of the flange P4. Reference numeral 6 denotes a ring-shaped limiting member (in which a minus groove is formed in this example), and a rear end face 6A.
An operation hole 6C facing the adjustment groove P6 is formed so as to penetrate toward the front end surface 6B from the front. A contact portion 6 that contacts the rear end surface P5 of the pilot screw P is provided on the front end surface 6B of the restriction member 6.
D is formed. In this example, the flat portion of the distal end surface 6B forms the contact portion 6D.

Adjustment of the pilot screw P is performed by fitting a flathead screwdriver into an adjustment groove P6 of the pilot screw P, and thereby rotating the pilot screw P. That is, the low-speed air-fuel mixture can be set thinner by turning the pilot screw P clockwise, and can be set thicker by rotating the pilot screw P counterclockwise. After adjusting the pilot screw, the control member 6 is press-fitted and fixed toward the insertion hole 4C.
What is particularly important here is that the operation hole 6C of the control member 6 is disposed facing the adjustment groove P6 when the control member 6 is press-fitted. A gap S is formed between the contact portion 6D of the front end surface 6B of the control member 6 and the rear end surface P5 of the pilot screw P.

According to the above, after the vaporizer is shipped from the production plant, the opening of the pilot screw P can be adjusted by a commercially available flathead screwdriver. That is, a minus screwdriver can be fitted into the adjustment groove P6 of the pilot screw P via the operation hole 6C of the restriction member 6,
Thereby, the pilot screw P can be screwed, whereby the effective opening area of the low-speed mixture passage 3 can be freely adjusted, and the low-speed mixture concentration can be adjusted. On the other hand, the rotation of the pilot screw P in the opening direction is restricted by the restriction member 6. That is, although the rear end face P5 of the pilot screw P and the contact portion 6D of the front end face 6B of the restricting member 6 have a gap S at the time of setting, the pilot screw P is rotated in a counterclockwise direction so that the pilot screw P When moving further away, the rear end face P5 of the pilot screw P comes into contact with the contact portion 6D of the front end face 6B of the limiting member 6 after moving toward the limiting member 6 corresponding to the gap S,
The subsequent counterclockwise rotation of the pilot screw P is mechanically prevented. According to the above, the pilot screw P is not large and does not unnecessarily open the low-speed air-fuel mixture passage 3, so that the concentration of the low-speed air-fuel mixture becomes abnormally high. In the above embodiment, the pilot screw P
After the adjustment, the restriction member 6 is press-fitted, but the pilot screw P may be adjusted after the restriction member 6 is press-fitted.

[0011]

As described above, according to the apparatus for adjusting a low-speed air-fuel mixture of a carburetor according to the present invention, an adjusting groove is provided on the rear end face of the pilot screw and the front end face of the restricting member is provided with a constant gap on the rear end face of the pilot screw. It is fixedly disposed, faces the adjusting groove on the rear end face of the pilot screw on the restriction member, is located at the front end face of the restriction member with the operation hole penetrating from the rear end face to the front end face of the restriction member, and the pilot screw passes through the gap. With a contact part that comes in contact with the rear end face of the pilot screw when it is moved to make it small, it is easy to use a pilot screw with a general commercial tool without preparing special special tools even after shipping from the factory. Can be adjusted by screwing. Further, the adjustment width can be adjusted only within a certain limited range since the rear end surface of the pilot screw abuts on the abutting portion of the front end surface of the restricting member. There is no increase in component emissions.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of an embodiment of a low-speed air-fuel mixture adjusting device for a vaporizer according to the present invention.

FIG. 2 is a vertical sectional view of a main part showing a first example of a conventional low-speed air-fuel mixture adjusting device for a carburetor.

FIG. 3 is a vertical sectional view of a main part showing a second example of a conventional low-speed air-fuel mixture adjusting device for a carburetor.

FIG. 4 is an upper plan view of the pilot screw from the X direction in FIG. 3;

[Explanation of symbols]

 P Pilot screw P5 Rear end surface P6 Adjustment groove 6 Restriction member 6A Rear end surface 6B Front end surface 6C Operation hole 6D Contact part

Claims (1)

[Claims] 1. A low-speed mixture passage which is screwed to a carburetor body and has a tapered needle valve portion at a tip, and variably controls an effective opening area of a low-speed mixture passage by being screwed in a longitudinal axis direction. In a low-speed mixture control device for a carburetor having a pilot screw for adjusting the low-speed mixture concentration flowing from the air into the intake passage of the carburetor, a pilot screw P
An adjustment groove P6 is provided on the rear end face P5, and a front end face 6B of the restricting member 6 is fixedly arranged with a constant gap S on the rear end face P5 of the pilot screw P. Coming to P6
When the pilot screw P is fixedly moved so as to make the gap S small in the operation hole 6C penetrating from the rear end face 6A to the front end face 6B from the rear end face 6A of the restriction member 6, A low-speed air-fuel mixture adjusting device for a carburetor, comprising: a contact portion 6D that comes into contact with a rear end face P5 of the screw P.