JPH1047164A - Manufacture of female thread for carbureter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a female thread for a carbureter for which it is possible to suppress the longitudinal and transversal displacements after the screwing motion adjustment of a screw member. SOLUTION: A hole before threading 3 is pierced along the longitudinal direction X-X from the end face 1A of a thread boss 1. The plural number of slit grooves 4 are pierced along the longitudinal direction X-X from the end face 1A of the thread boss 1, the inward ends 4A of the slit grooves 4 open into the hole before threading 3, and the outward ends 4B open into the outside diameter 1B of the thread boss 1. A female thread 5 is formed from the end face 1A of the thread boss 1 toward the hole before threading 3.

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 amount and concentration of air-fuel mixture supplied to an engine, and more particularly to adjusting screws such as a pilot screw and an air screw for adjusting the air-fuel mixture supplied to an engine. The present invention relates to a method for manufacturing a female screw of a carburetor, such as a female screw formed in a carburetor for screwing a screw, or a female screw for screwing a stop screw for adjusting a minimum idling opening of a throttle valve.

[0002]

2. Description of the Related Art A vaporizer has a pilot screw for adjusting and controlling a low-speed mixture amount, an air screw for adjusting and controlling an air amount, a stop screw for adjusting and controlling a minimum idling opening of a throttle valve, and the like. A screw member is mounted. These screw members are screwed to female threads formed in the screw boss of the vaporizer. Here, a screw hole is formed in the screw boss in a solid state, a female screw is machined toward the screw hole, and a screw member is screwed to the female screw. By screwing the screw member, the effective area of the passage formed by the screw member or the protrusion dimension of the screw member is controlled, and desired control is performed.

[0003]

According to such a conventional screwing of a screw member to a female screw, there is a gap between the female screw and the male screw of the screw member. After the adjustment, the screw member may move in the longitudinal direction corresponding to the gap, which makes it difficult to control the small effective area of the passage by the screw member or to control the small protrusion size of the screw member.

On the other hand, in order to solve the above-mentioned problem, a screw member is pressed by a spring in a fixed longitudinal direction of a female screw. According to this, although the stability in the longitudinal direction of the screw member can be improved, it is still difficult to suppress the lateral inclination of the screw member, and in particular, the screw member and the opening position formed by the passage are made uniform. Can not do. The reason that the screw member is inclined to the side is that there is a lateral gap between the male screw and the female screw of the screw member. Also, when the screw member is adjusted by pressing and screwing the screw member in the longitudinal direction with the tool, and then the pressing by the tool is released, the screw member may change in the longitudinal direction corresponding to the gap by the spring. This also hinders accurate position control of the screw member. In addition, in order to eliminate the gap, it is considered that the dimensional accuracy of the male screw and the female screw is equal to or higher than a first-class screw. However, according to this, the diameter management of the machined screw or the management of the screw tool becomes complicated, and the manufacturing cost is increased. It is not preferable because it causes an increase in the value.

[0005] A method for manufacturing a female screw of a vaporizer according to the present invention is as follows.
An object of the present invention is to provide a method for manufacturing a female screw, which can control the effective opening area and the protrusion size by a screw member with extremely high precision and can suppress an increase in manufacturing cost. It is in.

[0006]

In order to achieve the above object, a method for manufacturing a female screw of a vaporizer according to the present invention has a screw boss protruding from a vaporizer and a screw hole formed in the longitudinal direction of the screw boss from an end face of the screw boss. While being drilled, the inner end is opened to the screw lower hole, the outer end is opened to the outer shape of the screw boss, and a plurality of slit grooves are drilled from the end face of the screw boss along the longitudinal direction of the screw boss, A female screw is drilled from the end face of the screw boss into the screw lower hole.

[0007]

[Action] When drilling a screw with a tap in the screw lower hole,
The screw pilot hole receives the pressing force on the outer side of the circumference by the tap. Since a slit groove is formed in the screw lower hole,
In this portion, a female screw is formed in a state where the screw lower hole is expanded to the side. The root diameter of the female screw is formed to be smaller than the reference root diameter of the female screw formed when the female screw is formed in the screw lower hole having no slit groove. Therefore, when the screw member is screwed onto the female screw, the existence of the gap between the female screw and the male screw of the screw member is greatly reduced, and thus, the play in the longitudinal direction and the lateral side of the screw member can be completely suppressed, and proper tightening is performed. The screw member can be screwed onto the female screw with force.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for producing a female screw of a vaporizer according to the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a screw boss protruding upward from the vaporizer main body 2, and a longitudinal direction X of the screw boss 1 from the upper end surface 1 </ b> A of the screw boss 1.
A lower screw hole 3 is formed downward of -X. For example, when forming a 4 mm female screw,
A 3 mm screw hole 3 is formed. Reference numeral 4 denotes a slit groove. In the cross section of the screw boss 1, its inner end 4A is open to the screw hole 3, and its outer end 4B is the outer shape 1 of the screw boss 1.
B, and the slit groove 4 is formed downward from the upper end face 1A along the longitudinal direction XX of the screw boss 1. A plurality of the slit grooves 4 are formed in the cross section of the screw boss 1, and three slit grooves 4 are formed at 120 ° intervals in this example. The screw boss 1, the screw pilot hole 3, and the slit groove 4 are well shown in FIGS.

Then, a screw is formed by tapping from the end face 1A of the screw boss 1 to the prepared screw hole 3 including the slit groove 4, and a female screw 5 is formed in the prepared screw hole 3. This screwed state is shown in FIGS. According to such screw processing, in the screw hole 3A facing the slit groove 4, when the tap engages with the screw hole 3A, the screw boss 1 expands outward due to the resistance, and the screw hole 3A also extends outside. To expand. The reason why the screw boss 1 expands outward is that a plurality of slit grooves 4 are formed. According to the above, the root diameter D1 of the female screw 5A formed in the screw lower hole 3A facing the slit groove 4 is formed to have a small diameter corresponding to the amount of outward deformation of the screw boss 1. This is because the cutting edge portion of the tap does not sufficiently bite into the prepared screw hole 3A. On the other hand, the screw hole 3 below the slit groove 4
In the case of B, the screw boss 1 has sufficient rigidity at the time of threading with a tap, and the screw lower hole 3B does not expand and deform outward when female threading with the tap is performed. Is sufficiently bitten into the prepared screw hole 3A to form a female screw 5B having a reference valley diameter D2. That is, a female screw 5B having a reference valley diameter D2 is formed in the screw lower hole 3B below the slit groove 4, and a root diameter D1 having a diameter smaller than the reference valley diameter D2 is formed in the screw lower hole 3A facing the slit groove 4. Is formed.

Then, the screw member 6 having the male screw 6A is screwed to the female screw 5 formed as described above. That is, the male screw 6A of the screw member 6 is formed in the female screw 5A formed in the screw prepared hole 3A facing the slit groove 4 and in the screw prepared hole 3B formed continuously therefrom and below the slit groove 4. It is screwed onto the female screw 5B. According to the above, the male screw 6A of the screw member 6 has the female screw 5A facing the slit groove 4 having a smaller diameter D2 than the reference root diameter D2.
At this time, the screw boss 1 in the longitudinal direction X
A gap is not formed between the male screw 6A and the female screw 5A at -X and the outer side, and the screw is screwed in a tight meshing state. Note that a female screw 5 formed below the slit groove 4
In B, since the reference valley diameter D2 is formed, it is screwed into a meshing state with a gap as in the conventional case.

According to the above-described method for manufacturing a female screw of a vaporizer according to the present invention, a part of the male screw 6A of the screw member 6 is screwed tightly to the female screw 5A facing the slit groove 4, so that the screw member 6 is screwed. The movement of the screw member 6 in the longitudinal direction after the adjustment, and the screw member 6
The tilting movement to the side is completely suppressed. Therefore, the change of the effective opening area after the screwing adjustment of the screw member 6, the change of the projecting direction of the screw member 6, and the change of the lateral movement of the screw member 6 are completely suppressed. Can be controlled accurately. According to the above, there is no need to elastically position the screw member in one direction using a spring or the like.

The number of the slit grooves 4 and the number of the slit grooves 4
About the depth of the screw groove 6, the width of the slit groove 4, and the outer dimensions of the screw boss 1, the diameter of the male screw 6A of the screw member 6,
It is appropriately selected in consideration of the thread allowance of the male screw 6A and the female screw 5, the material of the screw boss 1, and the like.

FIG. 5 shows an embodiment in which the female thread manufacturing method of the present invention is used for a vaporizer. Reference numeral 2 denotes a carburetor main body through which an intake passage 21 penetrates. The screw boss 1 is formed to project upward from a part of the carburetor main body 2. Screw boss 1
The screw boss 1 is provided with a screw hole 3 downward from the end surface 1A. Further, the screw boss 1 has an inner end 4A opening downward from the end surface 1A of the screw boss 1 and an outer end 4B having a screw boss. A plurality of slit grooves 4 are formed in the outer shape 1B. Then, a female screw 5 is formed from the end face 1 </ b> A of the screw boss 1 toward the prepared screw hole 3, and a pilot screw as a screw member 6 is screwed toward the female screw 5. By screwing the screw member 6, the effective opening area of the sheet hole 22A of the low-speed air-fuel mixture passage 22 is variably controlled, and the low-speed air-fuel mixture controlled from the sheet hole 22A is supplied to the intake path 21 of the carburetor. Is done. According to the above, once the position is adjusted by screwing the screw member 6, the male screw 6A of the screw member 6 is tightly screwed into the female screw 5A formed in the screw lower hole 3A facing the slit groove 4. Therefore, the displacement of the screw member 6 in the longitudinal direction and the lateral displacement of the screw member 6 are completely suppressed, and extremely stable control of the low-speed air-fuel mixture can be performed.

In the above embodiment, a pilot screw is used as a screw member. However, a pilot screw is used for an air screw for adjusting the amount of air and a stop screw for adjusting the minimum opening of the throttle valve. May be.

[0015]

As described above, according to the method for manufacturing a female screw of a vaporizer according to the present invention, the screw boss protruding from the vaporizer has:
A screw hole is drilled from the end surface of the screw boss along the longitudinal direction of the screw boss, the inner end is opened to the screw hole, the outer end is opened to the outer shape of the screw boss, and the screw boss is extended from the end surface of the screw boss to the longitudinal direction of the screw boss. Since a plurality of slit grooves are formed along the screw boss, and a female screw is formed in the screw hole from the end face of the screw boss, the male screw of the screw member can be tightly engaged with the female screw facing the slit groove, and the screw member The displacement in the longitudinal direction and the side after the adjustment of (1) can be surely suppressed, so that the effective area of the passage and the protrusion dimension controlled by the screw member in the carburetor can be accurately controlled. Further, according to the above, it is not necessary to press and hold the screw member in a certain direction by an elastic member such as a spring, and according to this, the number of parts can be reduced. In addition, it is not necessary to raise the screw precision of the female screw formed in the screw lower hole and the male screw formed in the screw member to a first-class screw or more, thereby simplifying screw diameter management and screw tool management. It is.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a method for manufacturing a female screw of a vaporizer according to the present invention, in which a slit groove and a screw pilot hole are formed in a screw boss.

FIG. 2 is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view showing a state where a screw member 6 is screwed into the screw hole of FIG. 1;

FIG. 4 is a transverse sectional view showing a state where a screw hole is formed in a screw lower hole in FIG. 2;

FIG. 5 is a longitudinal sectional view of a main part in which the method for producing a female screw of a vaporizer according to the present invention is used for a pilot screw of the vaporizer.

[Explanation of symbols]

 Reference Signs List 1 screw boss 3 screw lower hole 3A screw lower hole facing slit groove 3B screw lower hole below slit groove 4 slit groove 4A inner end of slit groove 4B outer end of slit groove 5A female screw facing slit groove 5B slit groove Lower thread

Claims (1)

[Claims] 1. A screw hole 3 is formed in a screw boss 1 protruding from a carburetor along the longitudinal direction XX of the screw boss 1 from an end face 1A of the screw boss 1 and an inner end 4A of the screw boss 1 is formed. The screw boss 1 has a plurality of slit grooves 4 whose outer end 4B is open to the outer shape 1B of the screw boss 1 and is drilled from the end face 1A of the screw boss 1 along the longitudinal direction XX of the screw boss 1. A method for manufacturing a female screw of a vaporizer, wherein a female screw 5 is formed in the screw lower hole 3 from the end face 1A.