JP2005163611A - Inner pipe silencer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compatibly establish improvement of muffling characteristics and low exhaust resistance of a silencer for an internal combustion engine. <P>SOLUTION: An inner pipe 5 which is a straight pipe attached to a lead-in pipe 1 and a lead-out pipe 7 is provided in a muffler for the internal combustion engine using sound absorbing material 3 and a porous pipe 4 by an inner pipe fixing stay 6. Consequently, muffling effect is given without increasing exhaust resistance by leading high speed exhaust gas before entering the porous pipe 4 into the inner pipe 5 and drawing out turbulent exhaust gas in the porous pipe 4 by high speed exhaust gas at an outlet of the inner pipe 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to the shape of a silencer used for an internal combustion engine such as an automobile.

  As an example of a conventional silencer for an internal combustion engine such as an automobile, the one shown in FIGS. 7 and 8 is known. In the silencer shown in FIG. 7, the sound is silenced by the action of exhaust expansion, resonance, interference, resistance, and the like.

The muffler shown in FIG. 8 includes a porous tube 4 in which the introduction tube 1 and the introduction tube 7 are connected in a straight line, and a sound absorbing material 3 such as glass wool is filled in the chamber around the porous tube 4. The sound is silenced by the sound absorption characteristics of the material 3.
No.46-36670 JP 47-6804 A JP 47-14169 No. 14-11446 No. 44-31526

  In the silencer shown in FIG. 7, the silencing characteristics are good, but the exhaust resistance increases at high speed and high load, and the output of the internal combustion engine is significantly lost. On the other hand, in the silencer shown in FIG. 8, the exhaust resistance is low because it can be exhausted in a straight line, but it cannot absorb the low sound when the exhaust flow speed is low at low speed, and the discharged low sound is It was an unpleasant thing as a muffled sound.

  The problem to be solved is to provide a muffler for an internal combustion engine that can achieve both low exhaust resistance and improved muffler characteristics.

  The present invention provides a silencer for an internal combustion engine using a conventional sound-absorbing material and a perforated pipe by providing a straight pipe called an inner pipe so that exhaust having a high flow velocity before entering the perforated pipe is guided into the inner pipe. By exhausting the turbulent exhaust with the exhaust having a high flow velocity at the outlet of the inner pipe, the silencing effect is improved without increasing the exhaust resistance.

  Further, the inner pipe is characterized in that it is provided in the porous tube of the silencer for the internal combustion engine so that both the inlet side and the outlet side are longer than the entire length of the porous tube with a diameter of about half the diameter of the exhaust passage.

  ADVANTAGE OF THE INVENTION According to this invention, the silencing effect of the low-pitched sound can be raised, making use of the characteristic of the low exhaust resistance of the silencer for the internal combustion engine using the sound absorbing material and the porous tube.

  It can be applied to a silencer for an internal combustion engine having a conventional structure at low cost.

  As shown in FIG. 1, a silencer for an internal combustion engine formed of a sound absorbing material 3 and a perforated pipe 4 is attached with an inner pipe 5 on an inlet pipe 1 and an outlet pipe 7 by an inner pipe fixing stay 6. .

  As shown in FIG. 2, the exhaust discharged by the internal combustion engine is divided into exhaust that enters the inner pipe 5 and the perforated pipe 4 immediately before entering the silencer through the introduction pipe 1. The exhaust gas 8 passing through the inner pipe 5 is directed toward the outlet of the inner pipe 5 at the speed that has passed through the introduction pipe 1. The exhaust 9 passing through the porous tube 4 enters the sound absorbing material 3 from the hole of the porous tube 4 and is silenced, and returns to the porous tube 4. At this time, the flow of the exhaust gas 9 passing through the perforated pipe 4 is disturbed, and it becomes difficult to smoothly flow into the outlet pipe 7. However, as shown in FIG. 2, the exhaust 9 passing through the perforated pipe 4 is smoothly drawn by the exhaust 9 passing through the perforated pipe being drawn out to the exhaust 8 passing through the inner pipe 5 having a high flow velocity discharged from the inner pipe 5. It is discharged to the outlet pipe 7. Thereby, generation | occurrence | production of a low-pitched sound can be prevented.

  As shown in FIG. 2, the inner pipe 5 must be exhausted before the perforated pipe 4 because it is necessary to pass exhaust gas at the same speed as the flow speed passing through the introduction pipe 1.

  As shown in FIG. 3, the exhaust gas 8 passing through the inner pipe 5 must be longer than the porous tube 4 in order to draw out the exhaust gas 9 passing through the porous tube 4.

  As shown in FIGS. 5 and 6, the inner pipe 5 can achieve the effect even if it is not provided in the center of the porous tube 4, but the noise reduction efficiency is lowered.

  By adding to a conventional silencer for an internal combustion engine, the silencing effect can be improved.

It is sectional drawing of the silencer which shows one Embodiment of this invention. FIG. 2 is a side sectional view of the exhaust inlet of FIG. 1. FIG. 2 is a side cross-sectional view of the exhaust outlet of FIG. 1. FIG. 2 is a cross-sectional view taken along the line AA in FIG. It is sectional drawing of the silencer which shows other embodiment. FIG. 6 is a sectional view taken along the line BB in FIG. 5. It is sectional drawing of the conventional silencer. It is sectional drawing of the conventional silencer of the form different from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Introduction pipe 2 Outer cylinder 3 Sound-absorbing material 4 Porous pipe 5 Inner pipe 6 Stay for inner pipe fixing 7 Derived pipe 8 Exhaust gas through inner pipe 9 Exhaust gas through porous pipe 10 Exhaust gas entering / exiting porous tube 11 Absorbed by porous pipe 11 Disturbed exhaust 12 Exhaust drawn by exhaust passing through the inner pipe

Claims (2)

  By providing a straight pipe called an inner pipe to a silencer for an internal combustion engine that uses a conventional sound absorbing material and a perforated pipe, exhaust with a high flow velocity before entering the perforated pipe is led into the inner pipe, and is disturbed in the perforated pipe. A muffler for an internal combustion engine characterized by increasing the noise reduction effect without increasing the exhaust resistance by drawing out the exhaust gas at a high flow velocity at the outlet of the inner pipe.   2. The silencer according to claim 1, wherein the inner pipe is provided in the porous tube of the silencer so as to have a diameter that is approximately half the diameter of the exhaust passage and is longer on both the inlet side and the outlet side than the entire length of the porous tube.

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