JPH02284034A - Joint structure of press-in joint and method for measuring its fluid leak - Google Patents

Abstract

PURPOSE:To reduce a fluid leak part by linking a fluid passage with a diameter- increased part in terms of pressure by the communication path of the tip part of a pressure joint and making fluid pressure operates on the worked skin surface of the diameter-increased part corresponding to the guide part atop the press-in joint. CONSTITUTION:The opening part of the fluid passage 2 is closed, a die cast main body 1 is dipped in water, and specific air pressure is applied into the passage 2. This air pressure operates in the space of the guide part 7c of the press-in joint 7 through a cut groove 12 and if there is a blowhole in the diameter-increased part 3, air leaks out of the blowhole. Consequently, the air pressure is reduced and the air leak can be detected. The exposed surface of the worked skin of the diameter-increased part 3 is limited to the guide part 7c atop the joint 7, the pressure leak is therefore reduced correspondingly, and the yield of products is improved.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Field of Application This invention provides a method for connecting a fluid passage formed in a die-casting member with an external fluid passage at the open end of the fluid passage. The present invention relates to a joint that is press-fitted, a so-called press-fit joint, and more particularly to a structure of a joint portion that press-fits and holds the press-fit joint, and a method for measuring fluid leakage of the press-fit joint.

(2) Prior Art In recent years, molding by die casting has been increasingly used for the throttle bodies and carburetor bodies for internal combustion engines of automobiles from the viewpoint of ease of molding, precision, and strength. In the throttle body and the main body of the carburetor, a flow passage for an air passage, a fuel supply passage, or a flow passage for circulating running water for heating is provided.

FIG. 7 shows a conventional example of the joint structure, in which the press-fit hole C at the open end, which is larger in diameter than the inner part of the flow passage formed in the die-cast body a, is used for connecting the tube d. Press-fit joint e is press-fitted.

Such a conventional joint structure is disclosed in Japanese Utility Model Application Publication No. 60-143159.

In the structure of this joint part, a slight gap (approximately 3.0 mm or more) is usually maintained between the tip of the press-fit joint (e) and the deep part f of the press-fit hole C due to component tolerances during assembly. . Furthermore, a guide portion g is formed on the side surface of the tip end of the press-fit joint e, the diameter of which is smaller than the diameter of the main body of the press-fit joint e, for guiding the guide portion to the press-fit hole C. Therefore, a gap is formed between the press-fit:)-I ind e and the press-fit hole ○, which is made up of the gap element of the above-mentioned component tolerance and the gap element of the guide section g.

On the other hand, the press-fit hole C requires accurate roundness in order to receive the press-fit joint e, and is finished with a reamer by precisely scraping the surface of the cast surface.

At this time, the dense chill layer on the surface of the casting surface is scraped off, and the press-fit hole C becomes directly connected to the crystal structure region inside the casting, but there are no cavities inside the casting. ,
If the cavity communicates with the press-fit hole 〇, leakage may occur from this cavity.

2) In the conventional structure of the joint part, there is a risk of fluid leakage from the gap described in 7 above, so leakage measurement is not possible for the joint part where the press-fit joint e is press-fitted into the press-fit hole C. It is carried out as a work that cannot be done.

Since the conventional joint structure is as described above, there is a high probability of fluid leakage, resulting in poor product yield and creating a bottleneck in manufacturing.

(3) Problems to be Solved by the Invention The present invention is based on the above-mentioned circumstances, and aims to reduce the occurrence of fluid leakage in the joint structure of such a press-fit joint, and to enable fluid leakage measurement to be carried out as before. The purpose is to provide a structure that can maintain product reliability.

B1 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the joint structure is formed inside the main body by die-casting, has an enlarged diameter part on the open end side, and has an enlarged diameter part in the inner part. The reduced diameter part has a pressure fluid passage that is continuous with a stepped part; the tip side part has a guide part whose diameter is slightly smaller than the inner diameter of the enlarged diameter part, and the cast surface of the enlarged diameter part is cut. and a press-fit joint that is press-fitted after the pressure-fit joint has been removed, the distal end surface of the press-fit joint is in contact with the step surface of the enlarged diameter portion of the pressure fluid passage, and the pressure-fit joint is It is characterized in that a communicating path communicating with the guide portion is formed at the tip end.

In addition, as a measurement method for the joint part, it is formed inside the main body by die-casting, has an enlarged diameter part on the open end side, and a pressure fluid passage that is continuous with the reduced diameter part at the back with a stepped part; has a guide part whose diameter is slightly reduced than the inner diameter of the enlarged diameter part, and is press-fitted after the cast surface of the enlarged diameter part has been cut; The distal end surface is in contact with a step surface of the enlarged diameter portion of the pressure fluid passage, and
In the joint structure of the press-fit joint, in which a communication passage communicating with the guide part is formed at the distal end of the press-fit joint, pressurized fluid is sealed in the fluid passage to measure fluid leakage from the enlarged diameter part. It is characterized by

(2) Operation The communication passage at the tip of the press-fit joint provides pressure communication between the fluid passage and the enlarged diameter part, and the fluid pressure in the fluid passage remains unchanged on the machined surface of the enlarged diameter part corresponding to the guide part at the tip of the press-fit joint. Acts on the surface.

(3) Embodiment An embodiment of the 7111 construction and its fluid leak measuring method will be described based on the drawings.

111Z to 3 show the joint structure of one embodiment of the present invention, that is, FIG. 1 shows the overall structure of the joint portion, and FIGS. 2 and 3 show the partial structure thereof.

First, referring to FIGS. 1 and 2, reference numeral 1 denotes a die-cast body, and a pressure fluid passage 2 is provided in the die-cast body 1.

The fluid passage 2 includes an enlarged diameter section 3 at the open end and a reduced diameter section 4 at the inner part. It will be communicated to.

The fluid passage 2 is formed by a core or bottle body placed in a mold. That is, the core/bottle body is installed in advance in a mold, and after filling and solidifying the die-casting material into the mold, the fluid passage 2 is formed by removing the core/bottle body.

The enlarged diameter portion 3 is machined into a perfect circle by cutting its cast surface by reaming or the like in order to receive a press-fit joint 7 to be described later. Note that the inner diameter of the enlarged diameter portion 3 is the same from the opening end to the stepped portion 5.

The press-fit joint 7 has its tip end surface 7a in contact with the stepped portion 5, and its side circumferential surface 7b is in contact with the expanded diameter portion 3.
It is forcibly inserted into the inner wall of the

For this fitting operation, a guide portion 7c whose diameter is slightly smaller than the outer diameter of the main body of the press-fit joint 7 is formed on the peripheral surface of the front end side of the press-fit joint 7.

In this embodiment, the guide portion 7c consists of a cylindrical portion 8 and an inclined portion 9 whose diameter expands from the cylindrical portion 8 toward the outside of the main body of the press-fit joint 7 (see FIG. 3).

A bulging portion 7d is formed at the rear of the joint 7, and the rubber tube 10 is fitted elastically over the bulging portion 7d. 7e is a fluid passage within the press-fit joint 7.

Thus, in the distal end surface 7a of the press-fit joint 7, a cut groove 12 serving as a communication path is formed in the radial direction.

FIG. 3 schematically shows the detailed structure of the tip of this press-fit joint 7.

In FIG. 3, the press-fit joint 7 maintains liquid tightness by abutting the outer peripheral edge of its tip surface 7a with the stepped portion 5 circumferentially, but the cut groove 12 allows the guide portion 7C to connect to the enlarged diameter portion. It communicates with an annular space K surrounded by 3 and 3.

The depth of cut 12 is small in both width and depth, and
They may be provided at multiple locations in the radial direction of the tip surface 7a.

In addition, in the same figure, h is the thickness of the chill layer at the reduced diameter part 4 and the step part 5 (usually 0.05 to 0.3 a from the casting surface)
In the enlarged diameter portion 3 shown in ua), the cast surface is cut by IJ-ma finishing, and therefore the chill layer has disappeared.

In this joint section configured as described above, fluid leakage measurement is carried out as follows.

That is, the opening of the fluid passage 2 is closed, the die-cast body 1 is submerged in water, and a predetermined air pressure is applied inside the fluid passage 2.

Air pressure acts on the space K of the guide portion 7 of the press-fit joint 7 through the cut groove 12, and if there is a vr cavity in the enlarged diameter portion 3 of the part, air leaks to the outside through the cavity. Therefore, the air pressure decreases and air leaks can be detected.

According to the joint part structure of this embodiment, the exposed surface of the processed skin of the enlarged diameter part 3 is limited to the guide part 7C at the tip of the press-fit joint 7, which reduces pressure leakage and improves product yield. do. Furthermore, fluid leakage can be measured through the cut grooves 12, and the authenticity of the product can be maintained.

In this embodiment, making the cylindrical portion 8 of the guide portion 7C as short as possible is in accordance with the spirit of the present invention, and
The bent shape of the cylindrical part 8 and the inclined part 9 is eliminated, and 70'
(Dotted line in Figure 3). It is also possible to take a shape that connects directly as shown in (Other Embodiments) FIGS. 4 to 6 show other embodiments of the communication path of the present invention. In the figures, the same reference numerals are given to the same members as in the previous embodiment.

The embodiment shown in FIG. 4 is a communication hole 14 bored at the tip of the press-fit joint 7. The communication hole 14 is provided singly or at multiple locations.

In the fifth embodiment, a square-shaped cut groove, so-called square groove 16, is formed on the tip surface 7a of the press-fit joint 7.

In the embodiment shown in FIG. 6, the upper half of the tip end surface 7a of the press-fit joint 7 is cut off to form a step 18.

The present invention is not limited to the above-described embodiments, and various design changes can be made within the scope of the basic technical idea of the present invention.

C0 Effects of the Invention According to the present invention, the exposure of the machined skin at the enlarged diameter portion of the fluid passage is minimized, so the fluid leakage area is reduced.
This will improve product yield.

Moreover, pressure leakage measurement can be performed, and product reliability can be maintained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the overall structure of the joint part of a press-fit joint according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line XX in FIG.
Figure 3 is an enlarged view of the Y section in Figure 1, Figures 4 to 6
Each figure is a diagram showing other embodiments. FIG. 7 is a structural diagram of a conventional joint section. 1...Die-cast body, 2...Pressure fluid passage, 3...
... Expanding diameter part, 4... Reducing diameter part, 5... Step part, 7...
Press-fit joint, 7a... Tip surface, 7C... Guide portion, 12... Communication groove, 14... Communication hole, 16... V
Groove, 18...Step part Fig. 1

Claims (1)

[Claims] 1) A pressurized fluid passage formed inside the main body by die-casting and having an enlarged diameter part on the open end side and which is connected to the reduced diameter part at the back with a stepped part; a press-fit joint that has a guide part whose diameter is slightly smaller than the inner diameter of the enlarged diameter part and is press-fitted after the cast surface of the enlarged diameter part has been cut; The distal end surface of the press-fit joint is brought into contact with the surface of the stepped portion of the enlarged diameter portion of the pressure fluid passage, and the distal end of the press-fit joint is formed with a communicating path that communicates with the guide portion. Features a press-fit joint structure. 2) The joint structure of a press-fit joint according to claim 1, wherein the communication passage is a cut groove formed on the distal end surface of the press-fit joint. 3) The joint structure of a press-fit joint according to claim 1, wherein the communication passage is a communication hole bored at the tip of the press-fit joint. 4) The joint structure of a press-fit joint according to claim 1, wherein the communication passage is a stepped portion formed on the distal end surface of the press-fit joint. 5) It is formed inside the main body by die-casting, and has an enlarged diameter part on the open end side, and a pressure fluid passage that is connected to the reduced diameter part at the back with a stepped part; the tip side is the inner diameter of the enlarged diameter part. a press-fit joint that is press-fitted after the cast surface of the enlarged-diameter part is cut, and the tip surface of the press-fit joint is connected to the pressure fluid passage. In the joint structure of the press-fit joint, the joint structure of the press-fit joint is such that the press-fit joint is in contact with a step surface of the enlarged-diameter part, and a communication passage communicating with the guide part is formed at the distal end of the press-fit joint. A method for measuring fluid leakage of a press-fit joint, comprising: sealing a pressure fluid therein and measuring fluid leakage from an enlarged diameter portion of the pressure fluid passage.