JP2531644Y2 - Exhaust system flange joint for vehicles - Google Patents

Description

[Detailed description of the invention] [Industrial applications]

The present invention relates to a structure of a flange portion connecting an exhaust pipe to an exhaust pipe in an exhaust system of an automobile or the like.

[Prior art]

FIG. 5 shows an example of an entire automotive exhaust system widely used and put to practical use in the market. (1) is the engine, (2)
Is an exhaust manifold, (4) is a front exhaust pipe, (5) is a bellows, (6) is an intermediate exhaust pipe, (8) is an exhaust reburning device,
(10) is a rear exhaust pipe, (11) is a main silencer, (12) is an exhaust discharge pipe, and each exhaust pipe is connected to a corresponding flange (3) (7) (9) by an arc welding method. You. To specifically explain the flange connection, plate thickness 6mm to 1
Using a flat steel plate of 0 mm, the exhaust pipe is inserted into the center hole of the flange formed by the press punching method, and the entire circumference of the exhaust pipe or the entire circumference of the inside scene is welded by electric arc and joined. 54-88412). Fig. 6 shows a reinforcing flange (7) around the steel plate with a thickness of about 3mm to prevent bending by pressing and drawing.
This is a conventional example in which a boss having a low height is formed in a central portion, an exhaust pipe (6) is inserted into the boss, and an arc welding is performed between the outside of the exhaust pipe and an end face of the boss. In any of the flange joints described above, a gap of about 0.5 mm to 1 mm is provided between the outer diameter of the exhaust pipe and the diameter of the flange hole so that the exhaust pipe can be easily inserted into the flange hole. Exhaust gas leakage does not occur due to the arc welding over a long time. In addition to this, there is also a structure in which a concave portion is provided in the flange to accommodate the enlarged diameter portion at the end of the exhaust pipe, but it is necessary to provide a concave portion in the flange or to interpose a packing between the flanges.
The complicated structure of the manufacturing process also complicates the structure, and the fastening by the bent parts (projections 2 and 4) may be loosened. If the bent part is formed, the strength of the pipe will be significantly deteriorated at that part. There are disadvantages. Furthermore, in Japanese Utility Model Application No. 59-11265 (Japanese Utility Model Application Laid-Open No. 60-123489), a flange having a skirt having a similar shape to the enlarged diameter portion is superimposed on the enlarged diameter portion provided at the end of both pipes. There is an example in which both are TIG welded. However, since TIG welding does not fuse and weld the welding members together, for welding, a slit for TIG welding must be provided in the skirt portion of the flange which is the outer member,
Secondary materials such as wires and argon gas are required, and a skilled worker or a dedicated welding robot is required, resulting in high cost.

[Problems to be solved by the invention]

Conventionally, welding work time is long due to full circumference welding, and a welding wire and an inert gas are required as auxiliary materials, which is costly. Particularly in recent years, the use of stainless steel pipes has increased, and as for the electric arc welding over the entire circumference with the flange, it is necessary to use expensive stainless steel welding wires and similarly expensive argon gas as an inert gas. Coupled with the long time required, the production cost has risen significantly.

[Means for Solving the Problems]

Therefore, in the present invention, an annular boss is formed on the flange, the exhaust pipe is press-fitted, the tip of the exhaust pipe is fixed to the inner surface of the annular boss and expanded and fixed, and the exhaust pipe and the boss are spot-welded, that is, In a flange joint for connecting an exhaust pipe to an exhaust pipe, an annular boss (21) is formed by raising an inner surface R shape at the center of the flange, and the annular boss (2) is formed.
The exhaust pipe (24) is press-fitted into 1) and the tip of the exhaust pipe (24) is adjusted to the R shape of the inner surface of the boss.
The above-mentioned problem has been solved by forming the annular boss (21) and the exhaust pipe (24) by a plurality of spot welds (27) without welding the entire circumference. Regarding spot welding, a structure in which a plate-like inner member was fixed in a muffler by spot welding was seen in Japanese Utility Model Application Laid-Open No. 62-158119, and a mesh tubular body and an external material were used in Japanese Utility Model Application Laid-Open No. 61-102334. There are examples of spot welding of collars or inner collars, but spot welding is used instead of full circumference welding in the manufacture of flange joints that connect exhaust pipes that require strong, airtight and durability There is no suggestion to do so.

[Action]

With the above structure, the fixing is completed only by spot welding, so that the entire circumference is not required, and the expanded portion has the effect of increasing the joining strength and preventing the exhaust gas from leaking. This shortens the working time and eliminates the need for a welding wire and an inert gas, which were conventionally required.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 3 show a first embodiment of the present invention. In this example, in a flange joint connecting an exhaust pipe and an exhaust pipe, an annular boss (21) is formed at the center of the flange, and an exhaust pipe (24) is press-fitted into the annular boss (21) and the exhaust pipe ( An expanded portion (25) is formed by matching the tip of (24) to the R shape of the inner surface of the boss, and the annular boss (21) and the exhaust pipe (24) are fixed by a spot weld (27). This structure is further explained in detail together with the manufacturing method.
Pressing a thin steel plate of about m to make a flange (20)
Reinforcement flanges (22) and (23) for bending are formed integrally on the outer periphery of the flange, and an annular boss (21) having a height of about 30 mm is formed integrally at the center. The inner diameter of the annular boss (21) at the center is made smaller than the outer diameter of the exhaust pipe (24) to be joined, and the exhaust pipe (24) is used to press-fit the exhaust pipe (24) into the annular boss (21). When the outer diameter of the exhaust pipe is about 40%, ie, when the outer diameter of the exhaust pipe is about 40 mm, the shrinkage is given about 0.4 mm. Because of the press fit, no exhaust gas leakage occurs. After press-fitting the exhaust pipe (24) into the annular boss (21), the flange-side end face (25) of the exhaust pipe (24) is expanded, and is brought into close contact with the flange and the boss inner surface R. Thereafter, the annular boss (21) and the exhaust pipe (24) are fixed by a plurality of spot welds (24) without welding the entire circumference. The number of spots for this spot welding is desirably six for an automotive exhaust system flange joint from the comprehensive viewpoint of durability and manufacturing cost. FIG. 4 shows a second embodiment of the present invention. This is an example in which a bellows (5) is provided in an exhaust pipe (24). It has been previously proposed that the use of the bellows-integrated exhaust pipe also eliminates the need for welding the bellows (5) covered with a metal net and the exhaust pipe as shown in FIG. Hei 1-88511). An annular boss (21) is formed at the center of the flange, and an exhaust pipe (24) is attached to the annular boss (21).
To form an expanded part (25) with the tip of the exhaust pipe (24) conforming to the round shape of the inner surface of the boss, and spot weld (27) the annular boss (21) and the exhaust pipe (24). Is the same as that of the first embodiment.

[Effect of the Invention] The exhaust system flange joint for a vehicle according to the present invention has the above-described structure.
Since auxiliary materials such as a welding wire and an inert gas are not required, manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA in FIG. 2, FIG. 2 is a front view of the same, and FIG. 3 is a line BB in FIG. 2 of the vehicle exhaust system flange joint of the first embodiment of the present invention. It is sectional drawing. FIG. 4 is a sectional view corresponding to FIG. 1 of the second embodiment. FIG. 5 is a side view of the entire automobile exhaust system. FIG. 6 is a sectional view of a conventional flange joint corresponding to FIG. (1) engine, (2) exhaust manifold (3) (7) (9) flange, (4) front exhaust pipe (5) bellows, (6) intermediate exhaust pipe (8) exhaust reburning device, (10) after Exhaust pipe (11) Main silencer, (12) Exhaust discharge pipe (21) Annular boss, (24) Exhaust pipe (25) Expanded section, (27) Spot weld

Claims (1)

(57) [Scope of request for utility model registration] In a flange joint for connecting an exhaust pipe to an exhaust pipe, an annular boss (21) is formed by rising up into an inner surface R shape at the center of the flange, and an exhaust pipe (24) is formed on the annular boss (21). At the tip of the exhaust pipe (24), forming an expanded part (25) in conformity with the R shape of the inner surface of the boss, and welding the annular boss (21) and the exhaust pipe (24) all around. A flange joint for a vehicle exhaust system characterized by being fixed by a plurality of spot welds (27).