JPS5847210Y2 - Structure of the sliding part at the end of multiple tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in a slide portion provided at the end of a multi-pipe used for an exhaust pipe or the like for guiding engine exhaust gas to an exhaust gas purifier.

Conventionally, a multilayered exhaust pipe has been used to minimize heat loss of high-temperature exhaust discharged from an engine while guiding it to an exhaust purifier for early activation of the exhaust purifier. It is used for the purpose of heat shielding or radiated sound shielding for parts and floorboards.

For example, as shown in FIG. 1, the structure is such that an outer tube 1 is fixed to an inner tube 3 at a distal end 2 on the engine side, and a protrusion is provided in the middle of the outer tube 1 to prevent the inner tube 3 from sagging due to heat. 4 to support the inner tube 3.

Furthermore, when multiple tubes are used, the temperature of the inner tube 3 becomes higher than the temperature of the outer tube 1 due to the high temperature exhaust flowing through the inner tube 3, and the amount of thermal expansion of the inner tube 3 is equal to the thermal expansion of the outer tube 1. However, in order to absorb this difference in the amount of thermal expansion, a slide (■) is provided at the rear end portion 5 of the multiple tube to allow sliding in the length direction between the outer tube 1 and the inner tube 3. The difference in thermal expansion between the two tubes 1 and 3 is absorbed.

Conventionally, such a sliding portion has been designed to insert the inner tube 3 into the outer tube 1 through an annular collar 6 with a generally V-shaped cross section that is fixed to the inner peripheral surface of the outer tube 1, as shown in FIG. It was held concentrically and slidable.

However, according to the structure of such a conventional slide part,
It is very difficult to adjust the strength of the fit between the collar 6 and the inner tube 3.
For example, if the fit between the collar 6 and the inner tube 3 is too tight, the difference in thermal expansion will prevent the inner tube 3 from sliding relative to the collar 6, and for example, at a bent portion as shown by arrow A in FIG. The inner tube 3 undergoes buckling deformation, and eventually cracks occur at the bent portion of the inner tube.

Conversely, if the fit between the collar 6 and the inner tube 3 is too loose, the inner tube 3
resonates with engine vibrations and hits the collar 6, producing an abnormal noise (chattering sound).

Furthermore, due to the groove structure, production control is extremely difficult and the product has a high defect rate.

That is, the cross-sectional shape of the outer tube 1 and the inner tube 3 of the rear end portion 5 of the multi-tube where the sliding portion is provided is elliptical because the bent portion (arrow A portion) is formed near the rear end portion 5. When a collar 6 with a circular cross section is attached to the rear end 5, the collar is distorted.
If the attached part becomes loose or the collar 6 and inner tube 3
The strength of the fit may become too strong.

The present invention aims to provide a structure of a sliding portion at the end of a multi-tube, which eliminates the above-mentioned drawbacks.

Hereinafter, the present invention will be explained with reference to drawings showing embodiments.

Figures 2 and 3 show an embodiment of the collar 6 used in the slide section of the present invention.

The collar 6 is similar to the conventional collar shown in FIG.
The bulging portion 8 is formed by bulging the center of the short tube portion 7 with a circular cross section outward, but in the collar 6 of the present invention, the inner diameter b (the 3) is formed to be slightly larger (approximately Q, 2 myx) than the outer diameter of the inner tube 3.

Instead, a plurality of trapezoidal protrusions 10 and 10 are formed in an embossed manner on the inner surface of the short tube section 7 except for the bulging section 8, and the inner tube 3 is not rattled within the short tube section γ. It is constructed so that it can be fitted without any problem.

Here, the height of the protrusion 10 is such that the diameter a of the maximum inscribed circle touching the plurality of protrusions io, io is slightly smaller than the outer diameter of the inner tube 3 (
0.2 to Q, 5 mx).

The outer diameter of the bulging portion 8 is formed to be slightly larger than the inner diameter of the outer tube 1, as in the case of the conventional collar shown in FIG.

The collar 6 formed as described above is attached to a multi-tube slide M.
When attached to the collar 6, the collar 6 is fixed in the outer tube 1 by fitting the bulge 8 and the inner peripheral surface of the outer tube 1, and the inner tube 3 and the collar 6 are connected to the short tube of the collar 6. They come into contact and fit only at the trapezoidal protrusion 10 formed on the inner peripheral surface of the portion 7.

Therefore, the contact area between the collar 6 and the inner tube 3 can be smaller than that in FIG. 1, and the force required for the inner tube 3 to slide with respect to the collar 6 can be small.

Generally, in order to prevent the inner tube 3 from being damaged, it is necessary to suppress the force required for the above-mentioned sliding to less than 60 degrees, but according to the structure of the present invention using the collar as described above, it is possible to easily Moreover, since the inner tube 3 and the protrusion 10 are in contact with each other at the upper surface of the trapezoidal quadrangle, the inner tube has more resistance to sliding than, for example, a hemispherical embossed protrusion. can be added.

When the multi-pipe is used for an automobile exhaust pipe, the resistance by the protrusion 10 can be adjusted depending on the vehicle type.

In addition, since the protrusion 10 is in surface contact with the inner tube 3, there is less wear.
It is made of durable material and does not rattle in the sliding part.

The structure of the sliding part of the multiple tube of the present invention is such that the collar 6 constructed as described above is frictionally fixed to the outer tube 1 and the inner tube 3 is slidably inserted therein. The force required for sliding between the collar 6 and the collar 6 can be easily and reliably adjusted, and even if the outer tube or inner tube where the sliding portion is installed is distorted, the loosening will occur first in the area where the collar 6 is attached. This has great practical effects, such as lowering the product defect rate and lowering costs.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view showing a multiplex with a conventional slide structure, Figs. 2 and 3 show an embodiment of the collar used in the present invention, Fig. 2 is a side view, and Fig. B-B in Figure 2
FIG. 1...Outer pipe, 3...Inner pipe, 5...
... Rear end portion, 6 ... Collar, 7 ... Short tube portion, 8 ... Swelling portion, 10 ... Protrusion.

Claims (1)

[Scope of utility model registration request] Between the outer tube 1 and the inner tube 3 at one end of the multiplex tube, there is a bulge having an inner diameter slightly larger than the outer diameter of the inner tube 3 and a part of which has an outer diameter larger than the inner diameter of the outer tube 1. A trapezoidal protrusion 10 is formed on the inner surface of the short tube part 7 in which the protrusion 8 is formed, so that the diameter of the maximum inscribed circle with respect to the cross-sectional shape of the short tube part 7 at the part where the protrusion 10 is formed is the outer diameter of the inner tube 3. The structure of the sliding part at the end of a multi-tube is made by press-fitting a curler 6 which is stamped inward so that it is slightly smaller than the diameter.