JPS6141934Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in a fluid passage that uses a sound absorbing material to reduce the sound generated by fluid flowing inside.

Among the silencers installed in the exhaust system of automobiles, there is a sound-absorbing type silencer M using a sound-absorbing material. Conventionally, as shown in FIG. 1, such a muffler M has an inner pipe b installed inside an exhaust gas conduit a with a predetermined interval l so as to form a double pipe, and the exhaust gas is The gap between the conductive pipe a and the inner pipe b is filled with sound absorbing material c at a predetermined density. In addition, the inside of the pipe b is
A tube having a large number of small holes d in its peripheral wall, such as a perforated tube or a punched tube, is used (see, for example, Japanese Utility Model Application Publication No. 54-9243). Therefore, when the exhaust gas G flows through the exhaust gas conduit a, its sound waves are absorbed by the sound absorbing material c through the small holes d of the inner tube b, thereby reducing the sound.

Furthermore, in the exhaust system of a car, a sound absorbing structure part using a sound absorbing material C is sometimes provided in the exhaust pipe part, but in such cases, the structure is similar to that of the above-mentioned sound absorbing type muffler M. .

However, when adopting the sound-absorbing structure as described above, first, the inner pipe b is installed in the exhaust gas conduit pipe a, which serves as a fluid passage, and then the sound-absorbing material c is filled, but these steps are not necessary. is very troublesome.
Particularly when the fluid passage is bent, it is difficult to fill the sound absorbing material c in a predetermined manner, resulting in a significant decrease in assembly work efficiency.

Therefore, this invention can be easily assembled by simply winding a pre-prepared sound absorbing tube into a coil shape and inserting it into a predetermined position.
This provides a fluid passageway that can obtain sound absorption performance similar to that of conventional structures.

An embodiment in which the fluid passage according to the invention is applied to a muffler in an automobile exhaust system will be described below with reference to FIG. 2.

As shown in FIG. 2, the muffler 1 of this embodiment has a large number of exhaust sound guiding holes 3 in the peripheral wall 2.
Further, coiled sound absorbing tubes 5 having a predetermined pitch and filled with sound absorbing material 4 at an appropriate density are installed on the inner circumferential surface side of the exhaust gas conduit 6.

As shown in FIG. 3, the coiled sound absorbing tube (hereinafter simply referred to as tube) 5 is made of an aluminum alloy or a copper compound to form a heat-resistant spiral structure. The circumferential wall portion 2 of the tube 5 is thin and configured to have appropriate elasticity, and is brought into close contact with the inner circumferential surface of the exhaust gas conduit 6 by its elastic force. A sound absorbing material 4 made of glass wool or the like is housed inside this peripheral wall at a predetermined packing density. Note that the length and diameter of the tube 5 may be determined as appropriate depending on the location where it is installed, and it may also be installed in duplicate depending on the location where it is installed. Furthermore, as shown in FIG. 4, the tube 5 is constructed in a flexible shape that can be bent, so that it can be expanded and contracted while remaining in a coiled state.

As shown in FIGS. 2 and 3, the exhaust sound guiding holes 3 are arranged in large numbers over the entire surface of the peripheral wall, and are formed to have a diameter that prevents the sound absorbing material 4 inside the peripheral wall from being emitted. There is.

Emitted engine noise and the like are absorbed by the sound absorbing material 4 through the exhaust sound guiding holes 3 and are attenuated by sound absorption.

The exhaust gas conduit pipe 6 is formed into a cylindrical shape, as shown in FIGS. 2 to 4. This exhaust gas conduit pipe 6 is attached to a baffle plate constituting an expansion chamber (not shown) of the muffler M, so that a predetermined amount of exhaust gas G can be discharged.

Next, the operation of the silencer 1 configured as described above will be explained.

First, when filling the tube 5 with the sound absorbing material 4, the tube 5 of a predetermined length is expanded in advance, and the sound absorbing material 4 is packed into the tube 5 from one end using an appropriate press-fitting means. Then, the sound absorbing material 4 is sequentially fed from one side end to the other side end while being pressed. Once the sound absorbing material 4 is housed in the tube 5 with a predetermined packing density, the tube 5 is then wound into a coil at a predetermined pitch. Note that depending on the material, the tube 5 may be wound in a coil shape in advance, and the sound absorbing material 4 may be filled in along the coil shape. The tube 5 filled with this sound-absorbing material 4 can be installed at a predetermined position in the exhaust gas conduit 6 by press-fitting it through the opening 7 at one end of the exhaust gas conduit 6 to easily obtain a noise-reducing effect. It can be installed in the required position and exhibits sound silencing performance. Incidentally, since the tube 5 is resiliently locked within the exhaust gas conduit 6, there is no particular need for a locking means using a separate member.

In addition, since the tube 5 is configured in a coil shape, it can be installed even if the cross section of the exhaust gas conduit 6 is corrugated or extremely bent. This work is easy to do, and the sound absorbing material 4 is easy to attach.

As described above, the fluid passage of this invention has a coiled sound-absorbing tube with a predetermined pitch, which has a large number of sound-wave guiding holes in the peripheral wall, and is filled with sound-absorbing material at an appropriate density inside. Since it is designed to be installed on the inner peripheral surface of the flow path, it can be easily assembled as a sound absorption structure by simply winding a pre-prepared sound absorption tube into a coil shape and inserting it into the flow path. It is possible to obtain sound absorption performance similar to that of the structure.

Furthermore, this invention is not limited to application to the exhaust system of an automobile as in the above embodiment, but can be applied to various fluid passages that generate sound to obtain a desired silencing effect, and it goes without saying that various design changes can be made to the configuration as well without departing from the technical concept described in the claims of the utility model registration.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway sectional view showing the conventional mounting structure of the sound absorbing material filled part in a silencer, Fig. 2 is a cutaway sectional view of the main part showing an embodiment of this invention, and Fig. 3 is the installation of the same tube. FIG. 4 is a partially cutaway sectional view showing a modification of the same. DESCRIPTION OF SYMBOLS 1... Silencer, 2... Peripheral wall part, 3... Exhaust sound induction small hole, 4... Sound absorbing material, 5... Coiled sound absorbing tube, 6... Exhaust gas conducting pipe.

Claims (1)

[Scope of utility model registration request] A coiled sound-absorbing tube with a predetermined pitch, which has a large number of sound-wave-guiding small holes in the peripheral wall and is filled with sound-absorbing material at an appropriate density, is installed on the inner circumferential side of the flow path. Features fluid passages.