JP4533802B2 - Exhaust gas purification muffler for diesel engine - Google Patents

Description

  The present invention relates to a muffler for a diesel engine that discharges exhaust gas generated by the diesel engine while silencing, and in particular, for removing nitrogen oxide (NOx) or particulate matter (PM) contained in the exhaust gas. The present invention relates to an exhaust gas purification muffler for a diesel engine equipped with an exhaust gas purification material.

As a muffler for a diesel engine that exhausts exhaust gas generated by a diesel engine in recent years, for example, an exhaust gas purification material such as a diesel oxidation catalyst (DOC) or a diesel particulate filter (DPF) in the exhaust gas path. (See Patent Documents 1 and 2). The exhaust gas purification muffler for diesel engines has a structure that disperses the exhaust gas, and while ensuring a silencing function and an exhaust function, nitrogen oxide (NOx) and particulate matter (PM) contained in the exhaust gas. (See, for example, FIG. 5 of Patent Document 2).
JP-A-6-210135 JP 2002-70524 A

  However, since the exhaust gas purification muffler for diesel engines has a structure in which exhaust gas is dispersed in order to ensure a sound deadening function and an exhaust function, the exhaust gas temperature is reduced before reaching the exhaust gas purification material. For this reason, there exists a problem that the purification performance by an exhaust gas purification material cannot fully be exhibited.

  The present invention has been made in view of the above problems, and its purpose is to exhaust the exhaust gas generated by the diesel engine while silencing it, and to sufficiently exhibit the purification performance by the exhaust gas purification material. An object is to provide an exhaust gas purification muffler for a diesel engine.

  In order to solve the above-mentioned problems, the present invention exhausts exhaust gas generated by a diesel engine while silencing it, and removes nitrogen oxides (NOx) or particulate matter (PM) contained in the exhaust gas. An exhaust gas purification muffler for a diesel engine equipped with an exhaust gas purification material, wherein the exhaust gas purification unit is provided in an exhaust gas flow path in the muffler and holds the exhaust gas purification material, and upstream of the exhaust gas purification unit in the muffler A partition area in which an entrance silencer chamber and an entrance space are partitioned in order from the upstream side, a partition plate in which a passage hole communicating the entrance silencer chamber and the entrance space is formed, and an upstream end face in the muffler An exhaust gas introduction pipe having a discharge port formed in a region penetrating the inlet silencing chamber and having a downstream pipe port joined to the partition plate and penetrating the inlet silencing chamber; The partition plate through, and be provided with a bypass pipe for communicating the tube area of the exhaust gas introducing pipe and said inlet space.

  According to such a configuration, the exhaust gas flowing through the bypass pipe reaches the exhaust gas purification section directly without being dispersed in the inlet silencing chamber and while being kept warm by the bypass pipe. Thereby, the purification performance by the exhaust gas purification material is sufficiently improved.

  In addition, it is preferable that the bypass pipe has an upstream pipe port disposed upstream of the inlet silencer chamber and a downstream pipe port extending to a position immediately upstream of the exhaust gas purification unit.

  According to such a configuration, before the exhaust gas is taken into the inlet silencing chamber from the exhaust hole and dispersed, a large amount of exhaust gas is taken into the bypass pipe, and the exhaust gas at a higher temperature reaches the exhaust gas purification unit in the shortest distance. Can be made. Moreover, the heat retention area | region by a bypass pipe becomes long, and can also make exhaust gas of a higher temperature reach an exhaust gas purification part.

  The bypass pipe is preferably welded to the pipe wall of the exhaust gas introduction pipe or provided on the central axis of the exhaust gas introduction pipe. In particular, when the bypass pipe is provided on the central axis of the exhaust gas introduction pipe, the exhaust gas flowing through the bypass pipe will be kept warm by the double pipe structure surrounded by the bypass pipe and the exhaust gas introduction pipe, The exhaust gas purification unit is reached while maintaining a higher temperature state. Further, exhaust gas can be blown against the central region of the exhaust gas purification section, and furthermore, the exhaust gas resistance flowing through the bypass pipe and the exhaust gas introduction pipe can be reduced.

  According to the present invention, exhaust gas generated by a diesel engine is discharged while being silenced, and exhaust gas purification performance can be sufficiently exhibited.

Hereinafter, the best mode for carrying out an exhaust gas purification muffler for a diesel engine according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view showing an entire exhaust gas purification muffler for a diesel engine according to an embodiment of the present invention.

  As shown in FIG. 1, an exhaust gas purification muffler 20 for a diesel engine includes an exhaust gas purification unit 1 provided near the center of the muffler housing 17, and a partition plate 8 provided in an upstream region of the exhaust gas purification unit 1. The exhaust gas introduction pipe 10 provided on the upstream end face 6 of the muffler housing 17 and the bypass pipe 30 provided in the pipe of the exhaust gas introduction pipe 10 are provided.

  The exhaust gas purification unit 1 carries exhaust gas purification materials such as a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF), and nitrogen oxides (NOx) in the exhaust gas flowing in the exhaust gas flow path and Particulate matter (PM) is removed.

  The partition plate 8 divides the upstream region of the exhaust gas purification unit 1 into an inlet silencing chamber 4 and an inlet space portion 2, and a through-hole communicating with the inlet silencing chamber 4 and the inlet space portion 2 on a wall surface thereof. A plurality of 9 are formed. In addition, although the passage hole 9 shown in the figure is provided in the peripheral region of the partition plate 8, it may be provided in the central region where the exhaust gas introduction pipe 10 and the partition plate 8 are joined.

  The exhaust gas introduction pipe 10 is inserted from the upstream end face 6 of the muffler housing 17 and penetrates the inlet silencer chamber 4, and the downstream pipe port 18 is joined to the partition plate 8, and penetrates the inlet silencer chamber 4. A plurality of discharge holes 11 are formed in the region to be operated.

  The bypass pipe 30 is an exhaust gas pipe that penetrates the partition plate 8 and communicates the in-pipe region of the exhaust gas introduction pipe 10 and the inlet space 2, and an exhaust gas flow path that directly connects both spaces is formed in the pipe. Has been. Further, the upstream side pipe port 31 is arranged upstream of the inlet silencing chamber 4, while the downstream side pipe port 32 extends to the immediate upstream side of the exhaust gas purification unit 1.

  The downstream side of the muffler housing 17 also has a silencing structure, and a partition wall 16 is provided in the downstream region of the exhaust gas purification unit 1, and the outlet space 3, the outlet silencing chamber 5, and the like via the partition wall 16. It is divided into. Further, an exhaust gas outlet pipe 12 having a small hole 13 is inserted into the downstream end face 7 of the exhaust gas purification muffler 20, and an upstream port 19 is joined to the partition wall 16. In addition, the outlet silencer chamber 5 is provided with a plurality of silencer tubes 14 of the same length in which small holes 15 are formed, and the upstream port 21 thereof is connected to the partition wall 16 and via the partition wall 16. And communicate with the exit space 3. However, in the present invention, the configuration of the downstream region of the exhaust gas purification unit 1 is not particularly limited.

  In the above configuration, high-temperature exhaust gas accompanied by noise generated by a diesel engine (not shown) flows through the exhaust gas introduction pipe 10 and is introduced into the exhaust gas purification muffler 20. The introduced exhaust gas enters the inlet silencing chamber 4 through the discharge hole 11 formed in the exhaust gas introduction pipe 10 and is silenced by a silencing effect such as resonance or expansion while being dispersed. However, the temperature of the exhaust gas decreases with dispersion. The silenced exhaust gas enters the inlet space 2 through the passage hole 9 of the partition plate 8. The exhaust gas that has become substantially uniform in the inlet space 2 reaches the exhaust gas purification unit 1 on the downstream side and diffuses throughout the exhaust gas purification material. When the exhaust gas passes through the exhaust gas purification unit 1, a catalytic reaction of DOC and an adsorption reaction of DPF are performed in the exhaust gas purification material to remove nitrogen oxide (NOx) and particulate matter (PM) contained in the exhaust gas. Is done. Exhaust gas that has passed through the exhaust gas purification unit 1 reaches the outlet space 3 and flows into a plurality of muffler tubes 14 provided downstream thereof. The inflowing exhaust gas reaches the exit silencing chamber 5 from the small hole 15 formed in the muffler pipe 14 and is further taken into the exhaust gas outlet pipe 12 and discharged from the small hole 13 formed in the exhaust gas outlet pipe 12.

  Incidentally, as described above, the bypass pipe 30 is provided in the exhaust gas introduction pipe 10. Accordingly, a part of the exhaust gas introduced by the exhaust gas introduction pipe 1 is taken into the bypass pipe 30 and reaches the inlet space 2 without passing through the inlet silencer chamber 4, and exhaust gas purification is performed from the downstream pipe port 32. It is ejected to part 1. That is, the exhaust gas flowing through the bypass pipe 30 goes straight to the inlet space 2 and reaches the exhaust gas purification section 1 without being dispersed in the inlet silencer chamber 4 while being kept warm by the bypass pipe 30.

  Therefore, the exhaust gas that has flowed through the bypass pipe 30 and reached the exhaust gas purification unit 1 comes into contact with the exhaust gas purification material at a higher temperature than the exhaust gas that has passed through the inlet silencing chamber 4. The higher the exhaust gas temperature, the better the purification performance by the exhaust gas purification material. For example, the catalyst speed of DOC and the adsorption rate of DPF are improved. Therefore, the nitrogen oxide (NOx) and particulate matter (PM) are more efficiently removed from the exhaust gas flowing through the bypass pipe 30 than the exhaust gas passing through the inlet silencing chamber 4. Of course, the bypass pipe 30 is provided so as not to obstruct the flow of the exhaust gas, and does not impair the muffler function and the exhaust function as a muffler.

  Further, as described above, the bypass pipe 30 shown in the figure has the upstream-side pipe port 31 disposed on the upstream side of the inlet silencing chamber 4 and the downstream-side pipe port 32 located immediately upstream of the exhaust gas purification unit 1. It is extended to. Therefore, the upstream side pipe port 31 is arranged upstream of the discharge hole 11, and more exhaust gas can be taken into the bypass pipe 30 before the exhaust gas is taken in from the discharge hole 11. . On the other hand, the downstream side pipe port 32 ejects the exhaust gas from the immediate upstream side of the exhaust gas purification unit 1, so that the exhaust gas can reach the exhaust gas purification unit 1 in the shortest distance. Further, the region where the temperature is kept in the bypass pipe 30 becomes longer, and the exhaust gas in a higher temperature state can reach the exhaust gas purification unit 1.

  The bypass pipe 30 shown in the figure is fixed to the pipe wall in the exhaust gas introduction pipe 10 by welding or the like, but may be provided on the central axis of the exhaust gas introduction pipe 10. In order to provide the bypass pipe 30 in this manner, for example, a hole is formed in the central axis of the plate on which the exhaust gas flow path is formed, the bypass pipe 30 is inserted, and this plate is fixed in the exhaust gas introduction pipe 10 with a flange. That's fine.

  FIG. 2 is a schematic cross-sectional view showing an exhaust gas purification muffler in which the bypass pipe 30 is provided on the central axis of the exhaust gas introduction pipe 10. However, only the upstream side from the vicinity of the center of the exhaust gas purification muffler is shown, and the same or similar parts as in FIG.

  As shown in FIG. 2, when the bypass pipe 30 is provided on the central axis of the exhaust gas introduction pipe 10, the exhaust gas flowing through the bypass pipe 30 is doubled surrounded by the bypass pipe 30 and the exhaust gas introduction pipe 10. It is kept warm by the tube structure. Accordingly, the exhaust gas reaches the exhaust gas purification unit 1 while maintaining a higher temperature state. Further, the exhaust gas is blown to the central region of the exhaust gas purification unit 1 and permeates while uniformly diffusing into the exhaust gas purification material. Therefore, the contact area between the exhaust gas and the exhaust gas purification material increases, so that the exhaust gas purification performance is further improved. Moreover, the exhaust gas resistance flowing through the bypass pipe 30 and the exhaust gas introduction pipe 10 is reduced, and the influence on the silencing function and the exhaust function can be minimized.

  In addition, the installation location of the bypass pipe 30, the number of installation, etc. can be designed suitably. Further, the shape, size, material, and structure of the bypass pipe 30 are within the limits that do not impair the muffler function and the exhaust function as long as the exhaust gas purification material can sufficiently exhibit the purification performance. It can be changed as appropriate.

  For example, the vicinity of the pipe opening on the downstream side of the bypass pipe 30 may have a conical shape, and the diameter may be gradually expanded from the upstream side toward the downstream side. The material of the bypass pipe 30 may be a heat insulating material, or the bypass pipe 30 itself may have a double pipe structure.

It is a schematic sectional drawing which shows the whole exhaust gas purification muffler. It is a schematic sectional drawing which shows the upstream from the center vicinity of an exhaust gas purification muffler.

Explanation of symbols

1: exhaust gas purifying section, 2: inlet space section, 3: outlet space section, 4: inlet silencing chamber, 5: outlet silencing chamber, 6: upstream end face, 7: downstream end face, 8: partition plate, 9: passage Hole: 10: Exhaust gas introduction pipe, 11: Discharge hole, 12: Exhaust gas outlet pipe, 13, 15: Small hole, 14: Silencer pipe, 16: Partition wall, 17: Muffler housing, 20: Exhaust gas purification muffler, 30: Bypass tube

Claims (4)

Exhaust gas for diesel engines equipped with an exhaust gas purification material for discharging exhaust gas generated in a diesel engine while silencing and removing nitrogen oxides (NOx) or particulate matter (PM) contained in the exhaust gas A purification muffler,
An exhaust gas purification unit that is provided in the exhaust gas flow path in the muffler and holds the exhaust gas purification material;
A partition in which an upstream region of the exhaust gas purification unit in the muffler is partitioned in order from an upstream side into an inlet silencing chamber and an inlet space, and a passage hole is formed to communicate the inlet silencing chamber and the inlet space. The board,
Exhaust gas inserted into the muffler from the upstream end face and penetrating the inlet silencer chamber, and having a downstream pipe port joined to the partition plate and having a discharge hole in a region penetrating the inlet silencer chamber An introduction tube;
A bypass pipe that penetrates the partition plate and communicates an in-pipe region of the exhaust gas introduction pipe with the inlet space;
An exhaust gas purification muffler for a diesel engine characterized by comprising:   The bypass pipe has an upstream pipe opening disposed upstream of the inlet silencer chamber, and a downstream pipe opening extending to the immediate upstream side of the exhaust gas purification unit. Item 2. An exhaust gas purification muffler for a diesel engine according to Item 1.   The exhaust gas purification muffler for a diesel engine according to claim 1 or 2, wherein the bypass pipe is provided on a central axis of the exhaust gas introduction pipe. The exhaust gas purification muffler for a diesel engine according to claim 1 or 2, wherein the bypass pipe is welded to a pipe wall of the exhaust gas introduction pipe.

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