JP2009013902A - Silencer connected to exhaust system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dramatically improve discharge efficiency of residual water remaining in a shell of the silencer while effectively restraining generation of a noise in a silencer connected to an exhaust system of an internal combustion engine. <P>SOLUTION: A plurality of ventilation holes 32 are formed in a part of an outlet pipe 20. A cover 30 for covering the ventilation holes 32 is provided outside the outlet pipe 20 with a space 31 filled with a sound absorber 33 present between a part thereof. A water drain hole 35 is formed on the cover 30 for discharging residual water remaining in the bottom part of a shell 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a silencer connected to an exhaust system of an internal combustion engine such as a gasoline engine or a diesel engine. In particular, the present invention reliably ensures residual water remaining in the silencer while reducing the generation of noise as much as possible. The present invention relates to a silencer connected to an exhaust system of an internal combustion engine that can be discharged.

Conventionally, in a silencer connected to the exhaust system of an internal combustion engine, the moisture contained in the exhaust gas may be condensed and stored as residual water at the bottom of the shell that forms the outer shell of the silencer. A water drainage hole is formed in the outlet pipe located near the bottom of the shell, and the exhaust gas pressure in the outlet pipe becomes negative when the flow rate of the exhaust gas passing through the outlet pipe is large. It is known that the residual water inside is sucked into the outlet pipe and discharged into the atmosphere together with the exhaust gas (for example, see Patent Document 1 below).
JP 2006-2612 A

  However, what is disclosed in Patent Document 1 has the following problems.

(When there is a large amount of residual water in the bottom of the silencer shell)
If the residual water remaining at the bottom of the silencer shell increases and the water surface becomes higher than the height of the drain hole formed in the outlet pipe, a water surface is formed in the outlet pipe due to residual water at substantially the same level. The Thus, when the water surface by residual water is formed also in an outlet pipe, the following noises will be produced.

  (1) At locations where the exhaust gas enters in a direction that intersects the surface of the residual water formed in the outlet pipe (bends, etc.), the flow of the exhaust gas collides with the water surface, and the pressure of the exhaust gas that strikes it. Since it fluctuates due to pulsation, the water surface of the residual water in the outlet pipe swells. And in the location where the gap between the water surface and the inner surface of the outlet pipe is narrowed by this undulation, the flow velocity of the exhaust gas is increased, so that the residual water in the vicinity is blown off and noise due to the water blown off is generated.

  (2) Residual water sucked into the outlet pipe from the drain hole is ejected into the outlet pipe, and the exhaust gas pressure in the expansion chamber in the shell, that is, the pressure acting on the residual water level at the bottom of the shell is also the exhaust gas. Since it fluctuates due to pulsation, the momentum of the jet also fluctuates. As a result, the water surface of the residual water in the outlet pipe is “ramped”, and noise is generated due to the water surface rampage.

  (3) Exhaust gas collides with the rough surface of the water surface, and noise is generated by this collision.

  In particular, among the above (1) to (3), the noise of (2) and (3) due to the turbulent water surface is remarkable.

(When the amount of stored water at the bottom of the silencer shell is small)
This is the case where there is little residual water stored in the bottom of the silencer shell and the water surface is lower than the height of the drain hole formed in the outlet pipe, or there is no residual water in the bottom of the silencer shell.

  (4) The outlet pipe communicates with the expansion chamber through the drain hole, and the drain hole has a considerably larger hole area than the exhaust sound interference hole, so that the resonance frequency of the outlet pipe changes due to the drain hole. The silencing effect on the exhaust sound of a specific frequency using the resonance of the pipe is hindered.

  (5) Since the exhaust gas flow in the outlet pipe directly touches the drain hole, a whistling sound is generated.

  The present invention has solved the above-mentioned problems (2) to (5) among the above (1) to (5) while maintaining good discharge of residual water remaining in the shell through the drain hole. An object of the present invention is to provide a silencer connected to the exhaust system of a novel internal combustion engine.

In order to achieve the above object, the invention of claim 1 includes a shell, an inlet pipe provided in the shell and connected to an exhaust pipe of an internal combustion engine, an outlet pipe provided in the shell and opening to the atmosphere, And an expansion chamber that communicates both the pipes, the exhaust gas from the internal combustion engine is guided to the expansion chamber through the inlet pipe, and is further discharged to the atmosphere through the outlet pipe. A silencer connected to the exhaust system,
A plurality of vent holes are formed in a part of the outlet pipe, and a space is provided between the vent pipes. A cover that covers the vent holes is provided outside the outlet pipe, and the cover remains on the bottom of the shell. It is characterized by the formation of a drain hole for discharging residual water.

  In order to achieve the above object, the invention of claim 2 is characterized in that, in the invention of claim 1, the space is filled with a sound absorbing material.

  According to the first aspect of the present invention, since the residual water is sucked into the outlet pipe from the drain hole through the space and the plurality of vent holes, the ejection of the residual water into the outlet pipe is attenuated. It is possible to suppress the water surface fluctuation phenomenon and to prevent the occurrence of the noises (2) and (3) described above. In addition, by providing the space, it is not necessary to directly connect the inside of the outlet pipe to the expansion chamber through the drain hole, so that the change in the resonance frequency of the outlet pipe is reduced, and the exhaust of the specific frequency using the resonance of the outlet pipe is reduced. Decrease in the silencing effect on sound can be reduced. This improves the above (4). Furthermore, since the exhaust gas flow in the outlet pipe does not directly contact the drain hole, the whistling sound described in (5) can be prevented.

  According to the invention of claim 2, since the sound absorbing material is filled in the space formed between the cover and the outlet pipe, the sound absorbing effect of the exhaust sound by the sound absorbing material is obtained and the sound absorbing material is buffered. Due to this action, it is possible to more reliably prevent ejection of residual water into the outlet pipe, and the effect of preventing the above (2) and (3) can be further enhanced. Further, the sound absorbing material further ensures the separation between the inside of the outlet pipe and the water drainage hole, and the improvement effect on (4) and the prevention effect on (5) are further enhanced.

  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 this embodiment, the silencer of the present invention is applied to an exhaust system of an automobile internal combustion engine. FIG. 1 is a schematic plan view of the exhaust system of the internal combustion engine provided with the silencer of the present invention. FIG. 3 is a perspective view of the silencer shown in the arrow 2 of FIG. 1, FIG. 3 is a view of the arrow 3 shown in FIG. 2, FIG. 4 is a sectional view taken along line 4-4 of FIG. FIG. 6 is a sectional view taken along line -5, FIG. 6 is an enlarged view of a portion surrounded by an imaginary line 6 in FIG. 5, and FIG. 7 is a sectional view taken along line 7-7 in FIG.

  In FIG. 1, an exhaust system Ex for exhausting exhaust gas discharged by the operation to the atmosphere is connected to an internal combustion engine for an automobile, which is generally indicated by the symbol E. The exhaust system Ex is an internal combustion engine. The exhaust pipe 1 connected to the exhaust port of E includes a catalyst C, a pre-chamber P, and a silencer M that are sequentially connected from the upstream side to the downstream side.

  When the exhaust system Ex is connected to the internal combustion engine E, as shown in FIG. 7, the shell 2 of the silencer M is disposed with an inclination angle θ with respect to the horizontal plane, and the residual accumulated in the shell 2. Water is gathered at the front.

  The exhaust gas discharged from the operation of the internal combustion engine E is purified by the catalyst C to remove harmful components such as HC and NOx, is primarily silenced by the prechamber P, and is secondarily silenced by the silencer M to be discharged into the atmosphere. To be discharged.

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

  The shell 2 constituting the casing of the silencer M is formed of a shell body 2a formed by winding a plate material made of stainless steel into an elliptical cylinder shape and integrally joining both end edges thereof, and an airtight seal at its left and right opening ends. Before being caulked and fixed, the rear end plates 2b and 2c are formed in a sealed hollow oval shape. The elliptical shell 2 is connected to the downstream portion of the exhaust pipe 1 with its short axis side facing up and down. The exhaust pipe 1 communicating with the pre-chamber P is connected to the front end plate 2b of the shell 2, and the tail pipe 11 that opens to the atmosphere is connected to the rear end plate 2c in an airtight manner. .

  As shown in FIGS. 2 and 3, the sound deadening chamber in the shell 2 is divided into three expansion chambers by the first and second partition plates 3, 4, that is, the first, second and third expansion chambers 5, 6. And 7. Specifically, the first partition plate 3 and the second partition plate 4 are fixed in the shell 2 substantially in parallel with the front and rear end plates 2b and 2c with an interval in the longitudinal direction thereof. The first expansion chamber 5 is defined by the rear end plate 2c and the second partition plate 4 at the rear portion in the longitudinal direction of the shell 2, and the second expansion plate 5 has the second expansion plate 5 at the front side of the first expansion chamber 5. The second expansion chamber 6 is partitioned by the partition plate 4 and the first partition plate 3, and further, on the front side of the second expansion chamber 6, the first partition plate 3 and the front end plate 2 b are provided. Thus, the third expansion chamber 7 is partitioned.

  As shown in FIGS. 2, 4, 5, the first and second partition plates 3, 4 are formed with a large number of communication holes 8, 9 each consisting of a punching hole over substantially the entire area thereof. Communicates the second and third expansion chambers 6 and 7 with each other, and the communication hole 9 communicates the first and second expansion chambers 5 and 6 with each other.

  As clearly shown in FIGS. 2 and 3, the front end (upstream end) of the inlet pipe 10 disposed in the shell 2 is connected to and connected to the rear end (downstream end) of the exhaust pipe 1. The inlet pipe 10 is formed in a straight shape over the entire length thereof, and is penetrated and supported on one side in the lateral direction of the front end plate 2b, the first partition plate 3 and the second partition plate 4, and passes through the shell 2. It extends in the longitudinal direction, and its rear end (downstream end) is in open communication with the first expansion chamber 5. A portion of the inlet pipe 10 corresponding to the second expansion chamber 6 is formed with a discharge hole 12 made up of a plurality of small holes, and the inside of the inlet pipe 10 passes through the discharge holes 12 to form the second expansion chamber 5. Communicated within. Further, a portion of the inlet pipe 10 corresponding to the third expansion chamber 7 is formed with a plurality of exhaust interference holes 13 made up of small holes arranged in the circumferential direction, and the inlet interference holes 13 pass through the inlet interference holes 13. The pipe 10 communicates with the third expansion chamber 7.

  Therefore, most of the exhaust gas flowing into the inlet pipe 10 from the exhaust pipe 1 flows into the first expansion chamber 5 from its downstream end, and a part of the exhaust gas passes through the discharge hole 12 and is second expanded. The exhaust gas further flows into the chamber 6 through the exhaust interference hole 13 and flows into the third expansion chamber 7 where the exhaust noise is attenuated by the expansion and interference action of the exhaust gas, and the exhaust noise is primarily silenced. The exhaust gas flowing into the first expansion chamber 5 flows into the second expansion chamber 6 through the many communication holes 9 of the second partition plate 4, and the exhaust gas in the expansion chamber 6 After merging, the gas further flows into the third expansion chamber 7 through the many communication holes 8 of the first partition plate 3 and merges with the exhaust gas in the expansion chamber 7. The exhaust gas gathered in the third expansion chamber 7 flows into an outlet pipe 20 to be described later, and here, secondary silencing of the exhaust sound is effectively performed.

  An outlet pipe 20 is disposed in the shell 2 in parallel with the inlet pipe 10. The outlet pipe 20 as a whole is formed to be long by bending the shell 2 in an S-shape in the front-rear direction, and a U-shaped exhaust gas inlet pipe portion 21 and a straight exhaust gas discharge pipe portion 23. And an arc-shaped direction changing pipe portion 22 that connects the pipe portions 20 and 23 together.

  The exhaust gas inlet pipe portion 21 is formed in a U shape by a straight upstream portion 21A, a straight downstream portion 21B, and a semicircular direction changing portion 21C connecting them, The upstream portion 21A is offset from the center of the shell 2 to one side in the lateral direction (right side in FIGS. 4 and 5) and is at the middle in the vertical direction, while the downstream portion 21B is at the center of the shell 2. The upstream portion 21A and the downstream portion 21B are located above the upstream portion 21A, and the upstream portion 21A and the downstream portion 21B are integrally formed in the first expansion chamber 5 by a direction changing portion 21C inclined upward from the one side toward the central portion. It is connected in communication. The exhaust gas entry pipe portion 21 is provided across the first, second, and third expansion chambers 5, 6, and 7, and penetrates the first and second partition plates 3, 4. It is supported. The front end (upstream end) of the exhaust gas inflow pipe portion 21 is opened to the third expansion chamber 7, and the open end is expanded in a divergent shape so that the inflow amount of the exhaust gas into the exhaust gas inflow pipe portion 21. Have been to increase.

  On the other hand, the exhaust gas discharge pipe portion 23 is located lower than the exhaust gas entry pipe portion 21 and is located at a substantially central portion in the left-right direction in the shell 2 and substantially parallel to the axis of the shell 2. It arrange | positions and is penetrated and supported by the 1st, 2nd partition plates 3 and 4 and the rear-end plate 2c. The front end (upstream end) is connected to the direction changing pipe portion 22 in the third expansion chamber 7, and the rear end (downstream end) is opened to the atmosphere and connected to the tail pipe 11.

  As shown in FIGS. 2 and 3, the downstream end of the exhaust gas inlet pipe portion 21 located above the shell 2 and the upstream end of the exhaust gas discharge pipe portion 23 located below the shell 2 are These are connected by the direction changing pipe portion 22 disposed in the third expansion chamber 7 located in the front portion of the shell 2. The direction changing pipe portion 22 is formed in an arc shape by joining the two pipe halves 22h and 22h, and changes the direction of the exhaust gas flowing through the exhaust gas inlet pipe portion 21 downward from the front to the rear. While leading to the exhaust gas discharge pipe portion 23.

  As shown in FIGS. 6 and 7, a cylindrical cover 30 is provided on the outer peripheral surface of the intermediate portion of the exhaust gas discharge pipe portion 23 with an annular space 31. The exhaust pipe 23 is airtightly welded to the outer peripheral surface, and a large number of vent holes 32 made of punching holes are formed on the entire outer periphery of the exhaust gas exhaust pipe 23 covered by the cover 30. . Further, the annular space 31 is filled with a sound absorbing material 33 such as stainless wool or glass wool, and a part of the exhaust gas flowing in the exhaust gas discharge pipe portion 23 passes through a large number of vent holes 32. Flows to 33 and absorbs exhaust noise. A drain hole 35 (larger than the vent hole 32) is formed immediately below the rear portion of the cover 30. As will be described later, the exhaust flow of the exhaust gas flowing through the exhaust gas discharge pipe portion 23 causes the shell 2 to enter the shell 2. The remaining residual water W can be sucked into the exhaust gas discharge pipe portion 23 through the water drain hole 35 and discharged to the outside. At this time, since many slits are formed between the fibers of the sound absorbing material 33, a decrease in the suction flow rate of the residual water W can be suppressed to a low level, and the discharge performance of the residual water W is kept good. .

  Next, the operation of this embodiment will be described.

  Now, the internal combustion engine E is operated, and the exhaust gas discharged therefrom is guided to the exhaust system Ex. The exhaust gas flowing through the exhaust system Ex enters the silencer M, where main exhaust noise is silenced.

  As shown by arrows A in FIGS. 2 and 3, most of the exhaust gas flowing into the inlet pipe 10 from the exhaust pipe 1 flows into the first expansion chamber 5, and a part of the exhaust gas passes through a number of exhaust holes 12. The exhaust gas flows through the exhaust interference hole 13 to the third expansion chamber 7 through the exhaust expansion hole 13, and the exhaust gas flowing into the first expansion chamber 5 passes through the multiple communication holes 9 of the second partition plate 4. And then flows into the second expansion chamber 6, merges with the exhaust gas in the chamber 6, and then flows into the third expansion chamber 7 through the communication hole 8 of the second partition plate 3. In the meantime, the exhaust noise is effectively attenuated by the combined action of the expansion and interference of the exhaust gas, and the primary exhaust noise is silenced.

  The exhaust gas that has been primarily silenced flows from the third expansion chamber 7 into the outlet pipe 20 through the open end of the exhaust gas entry pipe portion 21 as indicated by an arrow B in FIGS. At this time, the upstream end (inflow end) of the outlet pipe 20 is widened so that the amount of exhaust gas flowing into the outlet pipe 20 increases. In addition, as described above, the outlet pipe 20 is bent in a S-shape and is extended to be long, so that the exhaust gas in the outlet pipe 20 is further attenuated while flowing through the pipe 20. Therefore, the mute is effectively performed. The exhaust gas that has been sufficiently silenced is discharged from the rear end of the exhaust gas discharge pipe portion 23 to the atmosphere through the tail pipe 11 as indicated by an arrow C in FIGS.

  In the exhaust gas silencing process, in the silencer M, the hot exhaust gas is cooled in the shell 2 and the water contained therein is dewed and condensed, or from the outlet pipe 20 to the shell 2 during car washing. Water that has entered the water remains.

  According to this embodiment according to the present invention, the residual water can be reliably discharged to the outside while suppressing the generation of abnormal noise, that is, the flow of exhaust gas flowing through the exhaust gas discharge pipe portion 23 of the outlet pipe 20. Residual water in the shell 2 is filled in the space 31 formed between the cover 30 and the outlet pipe 20 from the drain hole 35 formed in the cover 30 by the negative pressure of the exhaust gas pressure (see the solid line arrow in FIG. 7). It is sucked into the outlet pipe 20 via the sound absorbing material 33 and the plurality of vent holes 32 (see FIGS. 6 and 7, two-dot chain arrows), and is discharged from there through the tail pipe 11 to the atmosphere.

  By the way, the residual water is sucked into the outlet pipe 20 from the drain hole 35 through the plurality of ventilation holes 32 including the space 31 and the punching holes, so that the ejection of the residual water into the outlet pipe 20 is attenuated. As a result, it is possible to suppress the turbulence phenomenon of the water surface and to prevent the occurrence of the noises (2) and (3) described above. In addition, since the space 31 is provided, it is not necessary to directly connect the inside of the outlet pipe 20 to the first to third expansion chambers 5, 6, and 7 through the drain hole 35, so that the change in the resonance frequency of the outlet pipe 20 is small. Thus, the reduction in the silencing effect on the exhaust sound of a specific frequency using the resonance of the outlet pipe 20 can be reduced. This improves (4) above. Further, since the gas flow of the exhaust gas in the outlet pipe 20 does not directly contact the drain hole 35, it is possible to prevent the whistle blowing sound (5) described above.

  Further, since the sound absorbing material 33 is filled in the space 31 formed between the cover 30 and the outlet pipe 20, the sound absorbing effect of the sound absorbing material 33 can be obtained and the outlet pipe can be absorbed by the sound absorbing material 33. The ejection of residual water into the inside 20 can be more reliably prevented, and the effect of preventing the above (2) and (3) can be further enhanced. Further, the sound absorbing material 33 further ensures the separation between the inside of the outlet pipe 20 and the water drain hole 35, and further improves the improvement effect (4) and the prevention effect (5).

  Since the residual water sucked from the drain hole 35 of the cover 30 is dispersed from the plurality of vent holes 32 and sucked into the outlet pipe 20, the amount of residual water sucked, that is, the residual water drainage performance is kept good. It is. The sound absorbing material 33 is made of stainless wool, glass wool, or the like, and a large number of spaces are formed between the fibers. Therefore, the decrease in the suction flow rate of the residual water is small, and the drainage performance of the residual water is kept good.

  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, one drain hole is formed in the cover, but a plurality of drain holes may be formed. Moreover, in the said Example, although the some ventilation hole and cover are provided in the cylindrical shape in the whole circumferential direction of an outlet pipe, you may provide them only in the part which faces the bottom part side of a shell.

Schematic plan view of an exhaust system of an internal combustion engine equipped with the silencer of the present invention FIG. 1 is a perspective view of the silencer shown in the arrow 2 in FIG. 2 is a cross-sectional plan view of the silencer taken along line 3-3 in FIG. Sectional view along line 4-4 in FIG. Sectional drawing which follows the 5-5 line of FIG. Enlarged view of the phantom line encircled portion in FIG. Sectional view along line 7-7 in FIG.

Explanation of symbols

1 ... exhaust pipe 2 ... shell 5 ... expansion chamber (first expansion chamber)
6 ... Expansion chamber (second expansion chamber)
7 ... Expansion chamber (third expansion chamber)
10 .... Inlet pipe 20 ... Outlet pipe 30 ... Cover 31 ... Space 32 ... .... Vent holes (punching holes)
33 ... Sound-absorbing material 35 ... Water drainage hole E ... Internal combustion engine

Claims (2)

A shell (2), an inlet pipe (10) connected to the exhaust pipe (1) of the internal combustion engine (E) provided in the shell (2), and an outlet pipe (20 provided in the shell (2) and opened to the atmosphere ) And expansion chambers (5, 6, 7) communicating both pipes (10, 20) in the shell (2), and exhaust gas from the internal combustion engine (E) is passed through the inlet pipe (10). A silencer connected to the exhaust system of the internal combustion engine, led to the expansion chamber (5, 6, 7) via the outlet pipe (20), and discharged to the atmosphere from the outlet pipe (20),
A plurality of vent holes (32) are formed in a part of the outlet pipe (20), and a cover (30) covering the vent hole (32) is provided with a space (31) between the vent holes (32). An exhaust system for an internal combustion engine, characterized in that a drain hole (35) is formed on the cover (30) for discharging residual water remaining on the bottom of the shell (2). A silencer connected to the.   The silencer connected to an exhaust system of an internal combustion engine according to claim 1, wherein the space (31) is filled with a sound absorbing material (33).

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