JP4036459B2 - Silencer - Google Patents

Description

  The present invention relates to a silencer that is connected to an exhaust system of an engine for vehicles or the like to reduce exhaust noise.

Conventionally, an exhaust pipe is provided in the silencer, and the exhaust pipe that has flowed into the silencer is guided into the silencer and exhausted to the atmosphere. It is composed of a large-diameter exhaust pipe and a small-diameter exhaust pipe, and the small-diameter exhaust pipe is housed inside the large-diameter exhaust pipe. Are known (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-153019

  However, the one disclosed in Patent Document 1 is formed on the end wall (end plate) of the silencer as compared with the case where the two exhaust pipes provided in the silencer are taken out of the silencer in an independent state. There is only one insertion hole for the exhaust pipe, which is excellent in assembling property and can effectively use the internal space. On the other hand, the exhaust gas enters the large diameter exhaust pipe 28 from the downstream end of the small diameter exhaust pipe 27. When the gas is ejected, there is a problem that vortex flow is generated due to a sudden expansion of the exhaust gas flow path, resulting in high-frequency airflow noise.

  The present invention has been proposed in view of such a situation, and an object thereof is to provide a novel silencer that solves the above-described problems.

In order to achieve the above object, the invention of claim 1 comprises an exhaust pipe that silences the exhaust gas introduced into the silencer body and discharges it to the atmosphere by a small-diameter exhaust pipe and a large-diameter exhaust pipe, A silencer that collects two small-diameter and large-diameter exhaust pipes as one exhaust pipe within the silencer body by accommodating the small-diameter exhaust pipe inside the large-diameter exhaust pipe,
The downstream end of the small diameter exhaust pipe, is positioned upstream of the downstream end of the large径排air pipe, an exhaust gas flowing through the small diameter exhaust pipe is to be ejected from the downstream end of that the large径排air pipe The sound absorbing means for absorbing high-frequency airflow noise generated by the expansion of the exhaust gas ejected into the large-diameter exhaust pipe is large in a predetermined area extending from the downstream end of the small-diameter pipe to the upstream side and the downstream side thereof. It is provided around the diameter exhaust pipe.

According to the first aspect of the present invention, the downstream end of the small-diameter exhaust pipe is positioned upstream of the downstream end of the large-diameter exhaust pipe in the silencer body, and the large-diameter exhaust is discharged from the downstream end of the small-diameter exhaust pipe. Sound absorbing means for absorbing the flow noise of the exhaust gas ejected into the pipe is provided around the large-diameter exhaust pipe (40) in a predetermined region extending from the downstream end of the small-diameter pipe to its upstream side and downstream side . Therefore, it is possible to effectively absorb high-frequency airflow noise generated when exhaust gas is ejected from the downstream end of the small-diameter exhaust pipe into the large-diameter exhaust pipe.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on examples of the present invention shown in the accompanying drawings.

  In the accompanying drawings, FIG. 1 is an overall perspective view of an automobile exhaust system equipped with the silencer of the present invention, FIG. 2 is a front view of the secondary silencer as viewed in the direction of the arrow 2 in FIG. 1, and FIG. 4 is an enlarged sectional view taken along line 3-3, FIG. 4 is a sectional view taken along line 4-4 in FIG. 3, FIG. 5 is a sectional view taken along line 5-5 in FIG. 3, and FIG. FIG. 7 is an enlarged sectional view taken along the line 7-7 in FIG. 3, and FIG. 8 is a schematic view showing the operation of the secondary silencer.

  In FIG. 1, an exhaust system Ex is connected to an exhaust port of an automobile engine, and a primary silencer (prechamber) M1 and a secondary silencer M2 are connected in order from the upstream side to the downstream side of the exhaust system Ex. The exhaust gas flowing through the exhaust system Ex flows through the primary silencer M1 and is temporarily silenced, and further flows through the secondary silencer M2 and is secondarily silenced and discharged to the atmosphere.

  Next, the structure of the secondary silencer M2 according to the present invention will be described in detail with reference to FIGS.

  As shown in FIGS. 2 to 4, the secondary silencer M <b> 2 includes an exhaust pipe 20 including a silencer body 1, an exhaust introduction pipe 10, one small-diameter exhaust pipe 30, and one large-diameter exhaust pipe 40. And.

  The silencer main body 1 constitutes a main part of the secondary silencer M2, an outer cylindrical shell 2 having open front and rear end faces, and a front end plate that is airtightly fixed to the front opening of the outer shell 2. 3 and a rear end plate 4 which is airtightly fixed to the rear surface of the opening. The front end plate 3 is located on the front side of the vehicle. Inside the silencer body 1, a partition plate 5 is provided substantially in parallel with the front and rear end plates 3, 4, and an upstream chamber U is also provided between the partition plate 5 and the rear end plate 4. A downstream chamber D is defined between the plate 5 and the front end plate 3, and the upstream chamber U has a larger volume than the downstream chamber D. The upstream chamber U is divided into a first chamber U1 and a second chamber U2 by a support plate 6 parallel to the partition plate 5. A plurality of communication holes 7 are opened in the support plate 6, and the first chamber U1 and the second chamber U2 are communicated with each other through the communication holes 7, and the first chamber U1 and the second chamber. Between U2, the free flow of the exhaust gas can be allowed through the plurality of communication holes 7, and the first chamber U1 and the second chamber U2 substantially function as one upstream chamber U.

  In the silencer body 1, an exhaust introduction pipe 10 extending in the front-rear direction of the silencer body 1 is penetrated and supported by the front end plate 3, the partition plate 5, and the support plate 6. That is, the upstream end is opened to the outside of the silencer main body 1 and connected to the exhaust system Ex communicated with the exhaust port of the engine E. The rear end, that is, the downstream end of the exhaust introduction pipe 10 is connected to the upstream chamber U. Of the first chamber U1. A plurality of small holes 11 are opened in the middle of the exhaust introduction pipe 10, and the inside of the exhaust introduction pipe 10 is also communicated with the second chamber U <b> 2 through these small holes 11. Therefore, the exhaust gas discharged by the operation of the engine E flows into the exhaust introduction pipe 10 from the exhaust system Ex, and is led from there to the upstream chamber U in the silencer body 1.

  The silencer body 1 is provided with an exhaust pipe 20 for silencing the exhaust gas introduced into the silencer body 1 by the exhaust introduction pipe 10 and releasing it into the atmosphere. The exhaust pipe 20 is composed of one long small-diameter exhaust pipe 30 and one large-diameter exhaust pipe 40 that is shorter and larger in diameter.

  As shown in FIG. 3, the small-diameter exhaust pipe 30 is configured by connecting a plurality of straight pipes and U-shaped pipes in order to form a long loop as a whole. The first pipe 31, the U-shaped second pipe 32, the straight third pipe 33, the U-shaped fourth pipe 34, and the straight fifth pipe 35 are downstream from the upstream side in the exhaust gas flow direction. The muffler main body 1 is supported by a support plate 6, a partition plate 5 and a front end plate 3. The straight first pipe 31 is in the second upstream chamber U2 and its front end (upstream end) is opened in the second upstream chamber U2, and the U-shaped second pipe 32 is in the first upstream chamber U1. The straight third pipe 33 is disposed across the second upstream chamber U2 and the downstream chamber D, and the U-shaped fourth pipe 34 is outward from the front end plate 3. The extended and straight fifth pipe 35 is disposed across the downstream chamber D and the second chamber U2, and most of the fifth pipe 35 is accommodated in a large-diameter exhaust pipe 40 described later. The pipe 35 and the large-diameter exhaust pipe 40 are assembled into one. As shown in FIGS. 4 to 6, the fifth pipe 35 is provided on one side of the large-diameter exhaust pipe 40 and is fixed to the inner surface thereof. Further, the rear end (downstream end) of the fifth pipe 35 opens to the rear portion (downstream portion) in the large-diameter exhaust pipe, and as described later, the exhaust gas flowing through the fifth pipe 35 passes through the rear end. Are ejected into the large-diameter exhaust pipe 40.

  On the other hand, as shown in FIG. 6, the large-diameter exhaust pipe 40 is formed in a straight shape and is supported by penetrating the partition plate 5, the support plate 6 and the rear end plate 4, and its front end (upstream end) is It always communicates with the downstream chamber D, and its rear end (downstream end) is open to the atmosphere. In the rear portion of the large-diameter exhaust pipe 40, the outer periphery of the large-diameter exhaust pipe 40 in a predetermined region extending from the downstream portion of the small-diameter exhaust pipe 30, that is, the rear end (downstream end) of the fifth pipe 35. The surface is provided with sound absorbing means 41 for absorbing airflow noise of exhaust gas flowing therethrough. The sound absorbing means 41 includes a sound absorbing material 42 made of glass wool wound around the outer peripheral surface of the downstream portion of the large-diameter exhaust pipe 40, and a covering tube 43 made of a heat-resistant metal plate such as a stainless steel plate covering the outer periphery. ing. A plurality of sound absorbing holes 44 each having a small hole are formed in the downstream portion of the large-diameter exhaust pipe 40 covered with the sound absorbing means 41. As described later, the sound absorbing means 41 absorbs high-frequency airflow noise generated when the exhaust gas flowing through the small-diameter exhaust pipe 30 is ejected from the downstream end of the small-diameter exhaust pipe 30 into the large-diameter exhaust pipe 40. It becomes possible to do.

  As shown in FIG. 7, the partition plate 5 is provided with an opening 50 that communicates the second chamber U2 of the upstream chamber U and the downstream chamber D, and this opening 50 is opened and closed by a valve device V provided there. To be controlled. Since this valve device V is known in the art (see Japanese Patent No. 3383254) and is not the gist of the present invention, the valve device V will be briefly described as the structure of the valve device V. The valve is configured to open when the exhaust pressure rises in the high-speed rotation region of E, and is fixed to the partition plate 5 to communicate the second chamber U2 of the upstream chamber U and the downstream chamber D. A cylindrical valve housing 56, a spiral valve body 51 mounted on the valve housing 56, and a valve spring 52 for biasing the valve body 51 toward the closing side are provided. The outer peripheral portion of the valve body 51 is seated on the valve seat portion 56 a of the valve housing 56, and one spring receiver 54 is provided in the central portion of the valve body 51. The valve spring 52 is formed of a coil spring, and the body 52 a is supported by one spring receiver 54. Further, the two arm portions 52 b and 52 b of the valve spring 52 are slidably engaged with another spring receiver 55 provided integrally with the valve housing 56, and the valve body 51 is arm portions 52 b and 52 b of the valve spring 52. Is biased toward the valve closing side by the bending reaction force. The valve device V is opened when the exhaust pressure becomes equal to or higher than the valve opening set pressure corresponding to the set load of the valve spring 52 in the valve closing state.

  Thus, when the exhaust gas pressure in the upstream chamber U is less than or equal to a predetermined value, the valve body 51 is closed by the elastic force of the valve spring 52, and the second upstream chamber U2 and the downstream chamber D maintain a shielded state. In addition, when the exhaust gas pressure in the upstream chamber U exceeds a predetermined value, the valve body 51 is opened against the elastic force of the valve spring 52, and the second The upstream chamber U2 and the downstream chamber D are maintained in communication (see FIG. 8B).

  Next, the operation of this embodiment will be described.

  Exhaust gas generated by the operation of the engine E flows to the exhaust system Ex. The exhaust gas flowing through the exhaust system Ex is guided to the secondary silencer M2 according to the present invention through the primary silencer M1, and after being silenced, is released to the atmosphere.

  By the way, in the low speed operation region including the idling operation and the start operation of the engine E, as shown in FIG. 8A, the combustion pressure of the engine E is low and the pressure of the exhaust gas discharged therefrom is also low. Since the pressure of the exhaust gas flowing into the upstream chamber U through the pipe 10 is weaker than the valve closing spring force of the valve spring 52 of the valve device V, the valve device V maintains the closed state. Therefore, as shown by the arrow in FIG. 8A, all the exhaust gas flowing into the second silencer M2 flows from the exhaust introduction pipe 10 into the first chamber U1 and the second chamber U2, and from there, the small-diameter exhaust pipe. 30. The exhaust gas flowing in the small-diameter exhaust pipe 30 makes a U-turn to the front of the silencer main body 1 through the U-shaped second pipe 32 and further to the rear through the U-shaped fourth pipe 34. After making a U-turn again, it flows from the downstream end of the fifth pipe 35 to the downstream portion of the large-diameter pipe 40 and is discharged from there to the atmosphere.

  By the way, when the exhaust gas flows through the silencer body 1 in the low-speed operation region of the engine E, as described above, all of the exhaust gas flows through the small-diameter exhaust pipe 30, so that the flow path area is small and long. As a result, the silencing effect by the second silencer M2 in the low speed rotation region of the engine E can be enhanced. At this time, since the upstream chamber U functions as an expansion chamber and the valve device V is closed, the front end (upstream end) of the large-diameter exhaust pipe 40 is always open to the downstream chamber D. Since D functions as a low-frequency resonance chamber, both the upstream chamber U and the downstream chamber U can effectively contribute to the silencing effect, and the silencing effect can be achieved by effectively using the internal space of the silencer body 1. Can be further enhanced.

  On the other hand, when the combustion of the engine E is in a complete explosion state and reaches the high speed operation region, the combustion pressure becomes high and the pressure of the exhaust gas discharged from the high pressure region also becomes high, as shown in FIG. In addition, the pressure of the exhaust gas flowing into the upstream chamber U through the exhaust introduction pipe 10 becomes higher than the valve closing spring force of the valve spring 52 of the valve device V, and the valve device V is maintained in the valve open state. It reaches. Therefore, as shown by an arrow in FIG. 7B, the exhaust gas flowing into the first chamber U1 of the upstream chamber U from the exhaust introduction pipe 10 passes through the plurality of communication holes 7 ... of the support plate 6 to the upstream chamber U. Part of which flows into the small-diameter exhaust pipe 30, while the remainder flows through the valve device V to the downstream chamber D and from there into the large-diameter exhaust pipe 40. The exhaust gas that has branched in the small-diameter and large-diameter exhaust pipes 30 and 40 merges in the downstream portion of the large-diameter exhaust pipe 40, and the combined exhaust gas is discharged from the downstream end of the large-diameter exhaust pipe 40 to the atmosphere.

  By the way, when the exhaust gas flows through the second silencer chamber M2, as described above, the exhaust gas flows through the small-diameter and large-diameter exhaust pipes 30 and 40, so that the flow passage area is large and a part of the exhaust gas flows. As a result of flowing through a short path, the exhaust resistance of the silencer in the high-speed rotation region of the engine E can be reduced. Moreover, since both the upstream chamber U and the downstream chamber D can be functioned as an expansion chamber, the silencing effect can be enhanced by effectively utilizing the internal space of the silencer body 1.

Thus, in this embodiment according to the present invention, in particular, the downstream end of the small-diameter exhaust pipe 30 is positioned upstream from the downstream end of the large-diameter exhaust pipe 40, and the large-diameter from the downstream end of the small-diameter exhaust pipe 30p. The sound absorbing means 41 for absorbing the flow noise of the exhaust gas ejected into the exhaust pipe 40 is provided around the large-diameter exhaust pipe 40 in a predetermined region extending from the downstream end of the small-diameter pipe 30 to the upstream side and the downstream side thereof. Since it is provided, exhaust gas is ejected from the downstream end of the small-diameter exhaust pipe 30 into the large-diameter exhaust pipe 40 in both the low-speed operation region and the high-speed operation region of the engine E described above. Although high-frequency airflow noise is generated due to the rapid expansion of the exhaust gas, this airflow noise can be effectively absorbed by the sound absorbing means 41.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the Example, A various Example is possible within the scope of the present invention.

  For example, in the above embodiment, the case where the present invention is implemented in the second silencer M2 has been described. However, this may be implemented in the first silencer M1, and in the above embodiment, the silencer body 1 is provided. Although it is formed in an elliptical cylindrical shape, it may be formed in a cylindrical or other shape. Further, in the above embodiment, the sound absorbing means 41 is provided on the outer peripheral surface of the large-diameter exhaust pipe 40. The sound absorbing means 41 may be provided on the peripheral surface, and another sound absorbing material having the same effect may be used as the sound absorbing material instead of glass wool.

Overall perspective view of an automobile exhaust system equipped with the silencer of the present invention Front view of the secondary silencer as viewed in the direction of the arrow 2 in FIG. Enlarged cross-sectional view along line 3-3 in FIG. Sectional view along line 4-4 in FIG. Sectional drawing which follows the 5-5 line of FIG. Sectional drawing which follows the 6-6 line of FIG. FIG. 7 is an enlarged sectional view taken along line 7-7. Schematic showing the operation of the secondary silencer

Explanation of symbols

1 .... silencer body 20 ... exhaust pipe 30 ... small diameter exhaust pipe 40 ... large diameter exhaust pipe 41 ... sound absorbing means

Claims (1)

The exhaust pipe (20) that silences the exhaust gas introduced into the silencer body (1) and discharges it into the atmosphere is composed of a small-diameter exhaust pipe (30) and a large-diameter exhaust pipe (40). By placing (30) in the large-diameter exhaust pipe (40), two small-diameter and large-diameter exhaust pipes (30, 40) are arranged in the silencer main body (1) with one exhaust pipe (20). A silencer that gathers as
The downstream end of the small diameter exhaust pipe (30), is positioned upstream of the downstream end of the large径排air pipe (40), the exhaust gas flowing through the small diameter exhaust pipe (30) is large from the downstream end of its exhaust pipes (40) are adapted to jet into the sound-absorbing means (41) for absorbing the high frequency of the airflow noise generated by the expansion of the exhaust gas injected into the large径排air pipe (40), small diameter pipe A silencer characterized in that it is provided around the large-diameter exhaust pipe (40) in a predetermined region extending from the downstream end of (30) to its upstream side and downstream side .

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