JPH0433407Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (1) Industrial application field The invention is based on a method in which a metal insert nut is press-fitted and welded into a synthetic resin main body that constitutes at least a part of the vaporizer main body. The present invention relates to a component mounting structure for a carburetor in which a mounting component made of synthetic resin is attached to the main body portion by a bolt that is threaded into the insert nut.

(2) Conventional technology Conventionally, the structure for attaching such parts was to press fit and weld an insert nut into the main body part flush with the outer surface of the part, and then screw a bolt that passes through the attachment part into the insert nut. It is common to attach parts to the main body.

(3) Problems to be solved by the invention However, in the conventional method, the mounting parts are squeezed between the insert nut and the head of the bolt, so creep of the synthetic resin mounting parts may cause the bolt to tighten. Power loss may occur. Therefore, there is a method in which a metal collar that passes through the mounting part is brought into contact with the insert nut so that the collar receives the tightening force of the bolt, but since the end face of the insert nut is small, it has the disadvantage that it is difficult to receive the collar.
Moreover, regardless of whether a collar is used or not, when the insert nut is press-fitted into the main body, the press-fitting position of the insert nut is not determined, and the main body may be damaged.

The present invention has been made in view of the above circumstances, and aims to provide a structure for attaching parts of a carburetor that prevents damage to the main body part and also prevents a decrease in the tightening force of the bolts. .

B. Structure of the invention (1) Means for solving the problems According to the invention, in order to press fit the insert nut into the main body part, an enlarged diameter hole is provided at the opening end of the main body through a stepped part. A press-fit hole is provided in the insert nut, and the insert nut has a flange portion having an outer diameter that can be inserted into the enlarged diameter hole portion, abuts against the step portion, and is flush with the outer surface of the main body portion; A collar part that protrudes and passes through the mounting part is integrally provided, and the mounting part is held between the flange part and the main body part and the head of the bolt whose maximum tightening position is regulated by the end face of the collar part. Ru.

(2) Action By bringing the flange into contact with the step, the welding position of the insert nut to the main body is determined. Moreover, since the collar is integrally provided with the insert nut, there is no need for the troublesome work of bringing the collar into contact with the insert nut, and the maximum tightening position of the bolt is regulated by the flange, main body, and collar. Since the attachment part is held between the head and the head of the attachment part, it is possible to avoid applying an excessive tightening force to the attachment part.

(3) Embodiment An embodiment of the present invention will be explained below with reference to the drawings. First, in FIGS. 1 and 2, this carburetor is a composite type carburetor, and the main body 1
An automatic check yoke mechanism 3 including a check yoke opener 2, a throttle opener 4, a doss pot 5, a secondary throttle valve switch 6, an acceleration pump 7, and the like are attached.

Referring also to FIG. 3, the carburetor body 1 includes, in order from the bottom, a throttle body block 8,
It is constructed by stacking a mixture body block 9 and an air horn block 10 and connecting each block 8, 9, and 10 integrally. Moreover, mixture body block 9 and air horn block 10
is made of synthetic resin, and the throttle body block 8 is made of metal, such as aluminum.

A main intake passage 11 and a secondary intake passage 12 are installed in the carburetor body 1 in parallel. A mixture body block 9 forming an intermediate portion of the main intake passage 11 is provided with an outer bench lily 13, and an inner bench lily 14 is provided upstream of the outer bench lily 13. The air horn block 10 also includes the inner bench lily 14.
A throttle valve 15 located upstream of the outer bench lily 13 is eccentrically supported, and a throttle valve 16 located downstream of the outer bench lily 13 is supported eccentrically.

On the other hand, an outer bench lily 1 is attached to the mixture body block 9 that forms the middle part of the secondary intake passage 12.
7 is provided, and an inner bench lily 18 is provided upstream of the outer bench lily 17. Further, a secondary throttle valve 19 located downstream of the outer bench lily 17 is pivotally supported by the throttle body block 8.

Referring also to Fig. 4, air band switching valve 2
1, a valve housing 22 made of synthetic resin as a mounting part is fixed by bolts 23.
It is attached to an air horn block 10 as a main body made of synthetic resin, and a metal insert nut 24 is embedded in the air horn block 10 in order to screw and tighten a bolt 23.

The insert nut 24 is buried in the air horn block 10 by, for example, ultrasonic press-fitting, and in order to press-fit the insert nut 24, a bottomed hole 25 as a press-fit hole is bored on the outer surface of the air horn block 10. At the open end side of the bottomed hole 25, an enlarged diameter hole portion 27 whose diameter is enlarged via a stepped portion 26 is provided.

On the other hand, the insert nut 24 is basically formed into a cylindrical shape with a female thread 28 on the inner surface of the tip side, and from the tip side, the insert nut 24 has an outer diameter that is equal to or slightly smaller than the inner diameter of the bottomed hole 25. a first annular groove 30 having an outer diameter smaller than the outer diameter of the guide barrel 29; and a press-fitting part 31 having an outer diameter slightly larger than the inner diameter of the bottomed hole 25.
a second annular groove 31 having the same outer diameter as the guide tube portion 29; a flange portion 33 having an outer diameter that can be inserted into the enlarged diameter hole portion 27 of the bottomed hole 25; It consists of one annular groove 30 and a cylindrical collar portion 34 having the same outer diameter.

The length of the flange portion 33 is the depth d of the enlarged diameter hole portion 27.
1, and the length of the collar portion 34 is determined corresponding to the thickness d2 of the valve housing 22. Further, the length l1 from the flange portion 33 to the guide cylinder portion 29 is determined to be smaller than the depth d3 of the bottomed hole 25. Furthermore, the outer surface of the press-fitting part 31 is
A let 35 is provided.

The insert nut 24 is made of a metal having approximately the same coefficient of thermal expansion as the synthetic resin forming the air horn block 10. For example, the air horn block 10 is made of polyphenylene sulfide (PPS) containing glass fibers.
In order to obtain the impact strength and tensile strength necessary for a vaporizer, the glass fiber content is approximately 30 to 60%.
The thermal expansion coefficient at this time is 2.1 to 3.6×10 ^-5 cm/cm/
℃. An example of a metal with a coefficient of thermal expansion that is approximately equivalent to this is aluminum, which is approximately
The insert nut 24 is made of an aluminum alloy having a coefficient of thermal expansion of 2.4×10 ^-5 cm/cm/°C.

Further, the valve housing 22 is provided with an insertion hole 36 through which the collar portion 34 of the insert nut 24 is inserted, and the bolt 23 is inserted with a washer 37 between the end face of the collar portion 34 and the valve housing 22. It is screwed into the female thread 28 of the insert nut 24.

Next, to explain the operation of this embodiment, the insert nut 24 connects the flange portion 33 to the stepped portion 2.
It is press-fitted into the bottomed hole 25 using an ultrasonic press-fitting horn (not shown) or the like until it comes into contact with the bottom hole 25 . At this time,
Since the outer diameter of the press-fitting part 31 is larger than the inner diameter of the bottomed hole 25, the bottomed hole 2 that contacts the front edge of the press-fitting part 31
The inner surface of the insert nut 24 is melted and extruded forward, and the first annular groove 30 is filled with the molten resin, and the insert nut 24 is press-fitted into the bottomed hole 25 and welded. During press-fitting, the flange portion 33 comes into contact with the stepped portion 26, thereby determining the position of the insert nut 24, preventing excessive pushing by the ultrasonic press-fitting horn, and preventing damage to the air horn block 10 around the insert nut 24. The flange portion 33 is connected to the air horn block 10.
flush with the outer surface of.

With the insert nut 24 buried in the air horn block 10 in this manner, the valve housing 22 is brought into contact with the air horn block 10 while inserting the collar part 34 into the insertion hole 36, and the washer 37 is inserted into the end face of the collar part 34 and the air horn block 1.
The valve housing 22 is attached to the air horn block 10 by inserting the bolt 23 into the insert nut 24 so as to be interposed between the valve housing 22 and the air horn block 10. In other words, the maximum tightening position of the bolt 23 is regulated by the end face of the collar portion 34, and in this state, the valve housing 22 tightens the washer 37 between the flange portion 33 and the air horn block 10, and the head of the bolt 23. It will be held in a state interposed between it and the head of 23.

When a vehicle is operated with a carburetor with the valve housing 22 attached to the air horn block 10, the temperature of the carburetor body 1 changes frequently, but the insert nut 24 remains firmly attached to the air horn block 10. , it is possible to maintain high pull-out strength. That is, the air horn block 10 is fitted into the first and second annular grooves 30 and 32 of the insert nut 24, and the insert nut 24 is provided with a knurling 35, and the coefficient of thermal expansion of the insert nut 24 is similar to that of the air horn block. Since the coefficient of thermal expansion is approximately equal to 10, the insert nut 24 can be embedded in the air horn block 10 while maintaining a high pull-out strength even though the temperature of the carburetor body 1 frequently changes.

The valve housing 22 is attached by tightening bolts 23, but the tightening force of these bolts 23 is
Since it does not act on the valve housing 22 and is received by the collar portion 34, a decrease in axial force due to creep of the valve housing 22 or the like can be avoided. On this occasion,
The valve housing 22 is made of the same synthetic resin as the air horn block 10, such as glass fiber.
If it is made of polyphenylene sulfide containing about 60%, the decrease in the axial force can be more reliably prevented.

In the above embodiment, the insert nut 24 is welded to the air horn block 10 by ultrasonic press fitting, but it may also be welded by hot press fitting.

C. Effects of the invention As described above, according to the invention, the main body part has the following:
In order to press-fit the insert nut, a press-fit hole is provided which has an enlarged-diameter hole portion at its opening end, the diameter of which is enlarged through a stepped portion, and the insert nut has an outer diameter that can be inserted into the enlarged-diameter hole portion. A flange portion that contacts the stepped portion and is flush with the outer surface of the main body portion, and a collar portion that protrudes from the flange portion and penetrates the attachment part are integrally provided, and the end surface of the collar portion determines the screwing position. Since the mounting part is held between the head of the bolt to be regulated and the flange part and the main body part, the press-fitting position of the insert nut can be fixed at a constant position by bringing the flange part into contact with the step part, By providing the collar part integrally with the insert nut, it is possible to eliminate the difficulty of bringing the collar into contact with the insert nut, and the maximum tightening load of the bolt-mounted parts is kept constant between the flange part and the collar part. By restricting the tightening force to 1, it is possible to prevent the tightening force from decreasing due to creep of the attached parts.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a plan view of the carburetor, FIG. 2 is a view taken in the direction of the arrow in FIG. 1, and FIG. 3 is an enlarged sectional view taken along the line - Fourth
The figure is an enlarged sectional view taken along the line - in FIG. 2. DESCRIPTION OF SYMBOLS 1... Carburetor main body, 10... Air horn block as a main body part, 22... Valve housing as a mounting part, 23... Bolt, 24... Insert nut, 25... Bottom hole as a press-fit hole, 2
6...Step part, 27...Diameter enlarged hole part, 33...Flange part, 34...Collar part.

Claims (1)

[Scope of utility model registration request] A metal insert nut 24 is press-fitted and welded into the synthetic resin main body part 10 that constitutes at least a part of the carburetor main body 1, and the synthetic resin fitting 22 is screwed into the insert nut 24 by a bolt 23. In the carburetor component mounting structure that is attached to the main body portion 10, the main body portion 10 has an enlarged diameter hole portion 27 at the open end thereof, the diameter of which is enlarged via a step portion 26, in order to press fit the insert nut 24. A press-fit hole 25 is provided, and the insert nut 24 has a flange portion 33 having an outer diameter that can be inserted into the enlarged diameter hole portion 27, abuts against the step portion 26, and is flush with the outer surface of the main body portion 10. ,
A collar part 34 that protrudes from the flange part 33 and passes through the attachment part 22 is integrally provided, and the head of the bolt 23 whose maximum tightening position is regulated by the end face of the collar part 34, the flange part 33, and the main body. A carburetor component mounting structure characterized in that a mounting component 22 is held between a portion 10.