JP2012140964A - Exhaust gas purifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas purifier that adequately exhibits purifying performance of an exhaust gas by introducing the exhaust gas into an oxidation catalyst and a filter substantially evenly.SOLUTION: In the exhaust gas purifier, the oxidation catalyst 4 that purifies the exhaust gas and the filter 5 are housed in a case to configure a purification chamber 30. The introduction chamber 2 of the exhaust gas is formed in the case to fix a discharge introduction pipe 6 by being inserted into the introduction chamber vertically to the central shaft of the introduction chamber. The discharge gas introduction pipe is provided with a plurality of discharge gas holes 6b. The number of the discharge gas holes at a central position is different from that at the outer peripheral position of the introduction chamber, namely, a larger number of discharge gas holes are formed around the central position of the introduction chamber, and a smaller number of holes are formed around the outer peripheral position. The case is provided with a rectification plate 60 that partitions a purification chamber 30 and the introduction chamber 2. The rectification plates are provided with a plurality of passage holes 65. The number of the passage holes at the central position is different from that at the outer peripheral position, namely, a smaller number of holes are formed around the central position of the introduction chamber, and a larger number of holes are formed around the outer peripheral position thereof.

Description

  The present invention relates to a technique for uniformly introducing exhaust gas into an exhaust gas purification device.

  In recent years, environmental issues and health effects are concerned, so particulate matter in exhaust gas (hereinafter referred to as PM) discharged from diesel engines such as construction machinery, agricultural machinery, automobiles, ships, and generators. ) And nitrogen oxides (NOX) are being developed. For example, as described in Patent Document 1, when exhaust gas is introduced into an exhaust gas purification device, the temperature of the exhaust gas is increased by using a tapered pipe and an exhaust throttle valve, etc. A technique for introducing exhaust gas into (DPF) and removing PM and the like in the exhaust gas is known.

JP 2007-40220 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas purifying apparatus that can introduce exhaust gas substantially uniformly into an oxidation catalyst and a filter so that exhaust gas purification performance can be sufficiently exerted.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  The exhaust gas purifying apparatus according to claim 1, wherein an oxidation catalyst for purifying exhaust gas and a filter are housed in a case to constitute a purification chamber, and an exhaust gas introduction chamber is formed in the case, and the exhaust gas is discharged into the introduction chamber. The introduction pipe is inserted and fixed in a direction perpendicular to the center axis of the introduction chamber, and a plurality of discharge holes are provided in the exhaust introduction pipe, and the number of discharge holes is different between the center position of the introduction chamber and the outer peripheral side position. In this way, the center position of the introduction chamber is larger and the outer position of the introduction chamber is smaller.

  According to a second aspect of the present invention, the case is provided with a rectifying plate that partitions the purification chamber and the introduction chamber, the rectifying plate is provided with a plurality of passage holes, and the number of passage holes is different between the center position and the outer peripheral side position of the introduction chamber. In this way, the number is smaller at the center position of the introduction chamber, and is larger at the outer peripheral side of the introduction chamber.

  According to a third aspect of the present invention, the opening area of the exhaust hole of the exhaust introduction pipe is made different between the center position and the outer peripheral side position of the introduction chamber.

  According to a fourth aspect of the present invention, the opening area of the rectifying plate that partitions the purification chamber and the introduction chamber is made different between the center position and the outer peripheral side position of the introduction chamber.

  As effects of the present invention, the following effects can be obtained.

  According to the present invention, exhaust gas can be substantially uniformly discharged from the exhaust introduction pipe into the introduction chamber, and the exhaust gas can be substantially uniformly introduced into the oxidation catalyst and the filter. The performance can be fully exhibited.

1 is a schematic perspective view showing an exhaust gas purification apparatus according to Embodiment 1. FIG. 1 is an exhaust gas flow direction cutaway view showing an exhaust gas purification apparatus according to Embodiment 1. FIG. FIG. 6 is a schematic perspective view showing an exhaust gas purification apparatus according to Embodiment 2. FIG. 6 is a cutaway view in the exhaust gas flow direction showing the exhaust gas purification apparatus according to the second embodiment. (A) The schematic perspective view which shows the exhaust-gas purification apparatus which concerns on Example 3, (b) The schematic perspective view which shows the exhaust-gas purification apparatus which concerns on Example 4. FIG. FIG. 6 is a schematic perspective view of a cut surface in the exhaust gas flow direction showing the exhaust gas purifying apparatus according to the third embodiment and the fourth embodiment. FIG. 7 is a schematic perspective view showing an exhaust gas purifying apparatus according to Embodiment 5 and Embodiment 6. (A) Schematic which shows the partition plate and rectifier plate which concern on Example 5 and Example 7, (b) Schematic which shows the partition plate and rectifier plate which concern on Example 6 and Example 8. FIG. FIG. 10 is a schematic perspective view showing an exhaust gas purifying apparatus according to Embodiments 7 and 8. FIG. 10 is a schematic perspective view showing an exhaust gas purification apparatus according to Embodiment 9 and Embodiment 10. (A) Schematic perspective view showing an exhaust introduction pipe according to Embodiment 9, (b) Schematic perspective view showing an exhaust introduction pipe according to Embodiment 10.

  Next, embodiments of the invention will be described. First, the overall configuration of the exhaust gas purification device will be described with reference to FIG.

  An exhaust gas purifying device 1 for diesel engines (hereinafter simply referred to as an exhaust gas purifying device 1) includes an exhaust introduction pipe 6, an introduction chamber 2, an oxidation catalyst 4, a filter 5 (DPF), and an outlet portion 3. . Moreover, the thick arrow in each figure represents the flow of exhaust gas. The oxidation catalyst 4 is formed in a cylindrical case 10 as a casing, and similarly, the filter 5 is formed in a cylindrical case 20 as a casing. The upstream side of the exhaust gas is the introduction chamber 2, and the introduction chamber 2, the cylindrical case 10, the cylindrical case 20, and the outlet portion 3 are arranged in series in this order. In addition, as shown in FIG. 2, spaces 30 a, 30 b, and 30 c having predetermined intervals are provided on the upstream side, the downstream side, and the downstream side of the filter 5 of the oxidation catalyst 4 disposed in the purification chamber 30.

  Both the downstream end of the introduction chamber 2 and the upstream end of the cylindrical case 10 are formed with a flange-like flange portion 15. Similarly, the downstream end of the cylindrical case 10 and the upstream end of the cylindrical case 20 are A flange portion 15 is formed on both sides, and an annular gasket (not shown) is sandwiched between the flange portions 15 to maintain airtightness, and both are integrally fixed with a bolt (not shown) or the like. Yes. Also, a flange-like flange portion 15 is formed at the downstream end of the cylindrical case 20, and an annular gasket (not shown) is provided with a disc-shaped outlet portion provided with an opening at the substantially central portion of the flange portion 15. 3 is kept airtight by being sandwiched between 3 and is fixed integrally with a bolt (not shown) or the like. Here, the disc-shaped outlet portion 3 is fixed to the downstream end of the cylindrical case. However, the outlet portion 3 may be formed integrally with the cylindrical case 20, and the space portion 30c may be formed in the downstream portion. It is not limited. The oxidation catalyst 4 and the filter 5 are detachable from the cylindrical cases 10 and 20.

  An exhaust introduction pipe 6 that guides exhaust gas from the engine through an exhaust manifold (not shown) is disposed in the introduction chamber 2. Details of the insertion direction of the exhaust introduction pipe 6 with respect to the introduction chamber 2 will be described in each embodiment. An opening is provided at the tip or circumference of the exhaust introduction pipe 6 in the introduction chamber 2. That is, the exhaust gas is introduced into the introduction chamber 2 from the openings of the exhaust introduction pipe 6.

  The entire oxidation catalyst 4 at the rear stage of the introduction chamber 2 has a substantially cylindrical shape, and has a monolithic carrier (not shown) in which grid-like (honeycomb-like) passages are formed in the direction in which the exhaust gas flows. A catalytic metal such as platinum, rhodium or palladium is supported on the monolith support. Oxidizing power is imparted to nitric oxide (NO), carbon monoxide (CO), hydrocarbon (HC) and the like by the oxidation catalyst 4 by supporting the catalytic metal. In addition, although the material of the monolith carrier is cordierite in this embodiment, it is not particularly limited, and silicon carbide, stainless steel, or the like can be used.

  Further, the downstream filter 5 is a substantially cylindrical honeycomb filter having a polygonal cross section partitioned by porous partition walls made of ceramics such as cordierite. The filter 5 is configured by alternately sealing exhaust gas inlets and outlets of a large number of through holes formed in parallel with each other by these partition walls. The partition wall carries a catalyst metal such as platinum. Similar to the oxidation catalyst 4 described above, it has a catalytic function. In this embodiment, platinum is used as the catalyst metal, but there is no particular limitation, and palladium, rhodium, iridium, or the like can also be used. In each embodiment to be described later, the oxidation catalyst 4 and the filter 5 are arranged inside the exhaust gas purification device 1, but only the filter 5 having a catalytic function is arranged in the purification chamber 30 of the exhaust gas purification device 1. It is good also as a structure.

  Next, the exhaust gas flow and the purification method in the exhaust gas purification apparatus 1 will be described. In the above-described configuration, the exhaust gas is introduced into the introduction chamber 2 through an opening (details will be described later in each embodiment) provided in the exhaust introduction pipe 6 in the introduction chamber 2. Subsequently, the exhaust gas passes through the space 30 a in a substantially uniform state in the introduction chamber 2 at the preceding stage, and is introduced into the oxidation catalyst 4. The introduced exhaust gas is given an oxidizing power by the oxidation catalyst 4 and NO2 is generated from NO (an oxidizing power is also given to CO, HC, etc.). The exhaust gas that has passed through the oxidation catalyst 4 collects PM by the DFP 5. The collected PM is continuously oxidized and removed by combustion using the oxidizing power of NO2 and the like generated by the preceding oxidation catalyst 4 and DFP 5 and the high temperature of the exhaust gas near the engine. That is, the PM accumulated in the filter 5 is burned and removed, and the removing power of the filter 5 is regenerated. Exhaust gas from which PM has been removed by the filter 5 is discharged out of the exhaust gas purification apparatus 1 through a pipe (not shown) from an opening provided in the approximate center of the outlet portion 3. That is, accumulation of PM in the filter 5 in the oxidation catalyst 4 is prevented, and in addition to removal of PM, there are effects of reducing carbon monoxide, hydrocarbons, and the like. Further, in each of the embodiments to be described later, the concentrated deposition around the center of the conventional DFP 5 can be avoided by introducing the exhaust gas substantially uniformly.

  The above is the basic configuration of the exhaust gas purification device 1 and the exhaust gas purification method, which are common in the embodiments described later. Each example will be described below.

  1 and 2, exhaust gas discharged from the engine passes through an exhaust manifold and is introduced into an exhaust introduction pipe 6 having one end connected to the exhaust manifold. The other end of the exhaust introduction pipe 6 is inserted into the introduction chamber 2 so that the discharge direction is perpendicular to the central axis of the introduction chamber 2 and is eccentric. It is extended to. Further, the other end (tip) of the exhaust introduction pipe 6 is an opening 6a, and the exhaust gas turns into the introduction chamber 2 along the wall surface in the introduction chamber 2 from the opening 6a. And introduced. More specifically, the other end of the exhaust introduction pipe 6 is parallel to the tangential direction of the cylindrical introduction chamber 2, and the central axis of the exhaust introduction pipe 6 does not pass through the center of the introduction chamber 2. Inserted into. However, the central axis of the exhaust introduction pipe 6 may be inclined toward the purification chamber 30 so that a swirling flow is generated. Further, the opening 6a is disposed so as to be positioned at the center in the vertical direction of the introduction chamber 2 in FIG. However, the opening 6 a is a surface perpendicular to the central axis of the exhaust introduction pipe 6.

  With the above configuration, when the exhaust gas enters the introduction chamber 2 through the opening 6 a, the exhaust gas is guided to the inner wall of the introduction chamber 2 to form a swirling flow, and the exhaust gas is introduced into the introduction chamber 2 and the space before being introduced into the oxidation catalyst 4. It becomes substantially uniform in the part 30a, and it becomes possible to introduce the exhaust gas substantially uniformly into both the oxidation catalyst 4 and the filter 5. As a result, the performance of the oxidation catalyst 4 can be sufficiently exerted, and runaway combustion or the like can be avoided. In addition, a tapered tube or a swirl flow generator that previously required a space is not required, and a swirl flow can be obtained in a space-saving manner. Further, since the swirling flow can be obtained only by changing the insertion position of the exhaust introduction pipe 6 into the introduction chamber 2 and the exhaust introduction pipe 6 is simply inserted into the introduction chamber 2, it can be easily attached.

  3 and 4, the exhaust gas discharged from the engine passes through the exhaust manifold and is introduced into the exhaust introduction pipe 6 having one end connected to the exhaust manifold. The other end of the exhaust introduction pipe 6 is in a direction perpendicular to the central axis of the introduction chamber 2 and enters the introduction chamber 2 so that the central axis of the exhaust introduction pipe 6 and the central axis of the introduction chamber 2 intersect. The end of the exhaust introduction pipe 6 is inserted and fixed so that the exhaust introduction pipe 6 is closed on the inner wall opposite to the insertion port through which the exhaust introduction pipe 2 is inserted. A plurality of exhaust holes 6b, which are openings, are formed on the anti-oxidation catalyst 4 side of the exhaust introduction pipe 6, that is, on the surface opposite to the outlet.

  3 and 4, the exhaust gas discharged from the discharge hole 6b hits the inner wall on the opposite side to the outlet side of the introduction chamber 2 and bypasses the exhaust introduction pipe 6, thereby introducing the exhaust gas. The exhaust gas becomes substantially uniform at the downstream side of the chamber 2 and at the space 30a, and is introduced into the oxidation catalyst 4 and the filter 5 substantially uniformly. As a result, the performance of the oxidation catalyst 4 can be sufficiently exerted, and runaway combustion or the like due to uneven deposition of PM can be avoided. Further, since no accessories such as valves are involved, the exhaust introduction pipe 6 can be easily attached to the introduction chamber 2.

  In FIG. 5A and FIG. 6, the exhaust gas discharged from the engine passes through the exhaust manifold and is introduced into the exhaust introduction pipe 6 having one end connected to the exhaust manifold. The other end of the exhaust introduction pipe 6 is in a direction perpendicular to the central axis of the introduction chamber 2 and enters the introduction chamber 2 so that the central axis of the exhaust introduction pipe 6 and the central axis of the introduction chamber 2 intersect. The end of the exhaust introduction pipe 6 is inserted and fixed so that the exhaust introduction pipe 6 is closed on the inner wall opposite to the insertion port through which the exhaust introduction pipe 2 is inserted. A plurality of discharge holes 6 b are opened around the exhaust introduction pipe 6 in the introduction chamber 2. The size of the discharge holes 6b is the same, and the number of the discharge holes 6b is set so as to increase as the center side 10a of the introduction chamber 2 decreases as the outer peripheral side 10b. That is, the number of discharge holes 6 b proportional to the opening area of the space 30 a is opened on the outer periphery of the exhaust introduction pipe 6 in the introduction chamber 2.

  With the above configuration, as shown in FIG. 6, a large amount of exhaust gas discharged from the exhaust introduction pipe 6 is exhausted from the center side of the introduction chamber 2 and gradually decreases toward the periphery. The exhaust gas is discharged from the discharge hole 6b in proportion to the length from the wall to the wall surface of the introduction chamber 2 in the perpendicular direction, that is, in proportion to the opening area of the space 30a in FIG. . Therefore, the exhaust gas becomes substantially uniform in the vicinity of the space 30 a and can be introduced almost uniformly into the oxidation catalyst 4 and the filter 5. As a result, the performance of the oxidation catalyst 4 can be sufficiently exerted, and runaway combustion or the like can be avoided. The exhaust introduction pipe 6 can be easily attached to the introduction chamber 2. Further, the exhaust hole 6b of the exhaust introduction pipe 6 can be easily opened with a drill or the like.

  5B and FIG. 6, the exhaust introduction pipe 6 is inserted into the introduction chamber 2 and fixed in the same manner as in the third embodiment. In the present embodiment, the plurality of discharge holes 6b provided in the entire peripheral wall of the exhaust introduction pipe 6 in the introduction chamber 2 are arranged substantially uniformly, and the opening area thereof is larger toward the center side 10a and gradually toward the peripheral side. It is small. In other words, the opening area of the discharge hole 6b is larger at the central side 10a of the introduction chamber 2 and smaller at the outer peripheral side 10b. That is, the discharge holes 6b are opened at a constant interval on the outer periphery of the exhaust introduction pipe 6 in the introduction chamber 2, and the opening area of the discharge holes 6b is proportional to the opening area of the space 30a where the holes are located. Has been.

  With the above configuration, as shown in FIG. 6, a large amount of exhaust gas discharged from the exhaust introduction pipe 6 is exhausted from the center side of the introduction chamber 2 and gradually decreases toward the periphery. The exhaust gas is discharged from the discharge hole 6b in proportion to the length from the wall to the wall surface of the introduction chamber 2 in the perpendicular direction, that is, in proportion to the opening area of the space 30a in FIG. . Therefore, the exhaust gas becomes substantially uniform in the space 30 a and can be introduced almost uniformly into the oxidation catalyst 4 and the filter 5. Therefore, the performance of the oxidation catalyst 4 can be sufficiently exerted to avoid runaway combustion or the like. Further, the exhaust introduction pipe 6 can be easily attached to the introduction chamber 2. The size of the discharge hole 6b only needs to change the diameter of the drill.

  7 and 8A, the exhaust gas discharged from the engine passes through the exhaust manifold and is introduced into the exhaust introduction pipe 6 having one end connected to the exhaust manifold. The other end of the exhaust introduction pipe 6 is in a direction perpendicular to the central axis of the introduction chamber 2 and enters the introduction chamber 2 so that the central axis of the exhaust introduction pipe 6 and the central axis of the introduction chamber 2 intersect. The end of the exhaust introduction pipe 6 is inserted and fixed so that the exhaust introduction pipe 6 is closed on the inner wall opposite to the insertion port through which the exhaust introduction pipe 2 is inserted. A plurality of discharge holes 6 b having the same area are opened at equal intervals around the exhaust introduction pipe 6 in the introduction chamber 2. Here, in addition to the basic configuration, as shown in FIG. 7, a partition plate 50 is provided between the introduction chamber 2 and the purification chamber 30 that houses the oxidation catalyst 4 and the filter 5. . That is, a partition plate 50, which is a circular plate in plan view, is provided near the downstream end of the introduction chamber 6 so as to be fixed to the flange portion 15 at the upstream end of the cylindrical case 10. A plurality of communication holes 55 are opened in the partition plate 50 in a substantially radial manner, and the number of the communication holes 55 is smaller at the center side of the introduction chamber 2 and more at the outer peripheral side.

  With this configuration, when exhaust gas is introduced into the oxidation catalyst 4 or the filter 5 through the communication hole 55 of the partition plate 50 provided on the downstream side of the introduction chamber 2, unevenness of the exhaust gas can be reduced. it can. Moreover, the communication hole 55 which is an opening part of the partition plate 50 plays the role of a silencer, and can reduce the noise by flowing exhaust gas. Further, the communication hole 55 that is an opening of the partition plate 50 can be easily opened by drilling or punching.

  7 and 8B, the exhaust introduction pipe 6, the introduction chamber 2 and the like have the same configuration as in the fifth embodiment, and the size of the plurality of communication holes 55 provided in the partition plate 50 is smaller toward the center side and closer to the outer periphery side. The structure is large. That is, the plurality of communication holes 55 provided in the partition plate 50 are opened concentrically at regular intervals, and the opening area of the communication holes 55 is smaller toward the center of the introduction chamber 2 and gradually toward the outer periphery. It is provided to be larger.

  When the exhaust gas substantially uniformized by this configuration is introduced into the oxidation catalyst 4 and the filter 5 through the communication hole 55 of the partition plate 50 provided on the downstream side of the introduction chamber 2, unevenness of the exhaust gas is further reduced. Can do. In addition, the communication hole 55 which is an opening of the partition plate 50 serves as a silencer and can reduce noise caused by the flow of exhaust gas. Moreover, the communication hole 55 which is an opening part of the partition plate 50 should just change magnitude | sizes, such as a drill or punching. In addition, the partition plate 50 of the said Example 5 or Example 6 can also be set as the structure arrange | positioned between the introduction chamber 2 and the purification | cleaning chamber 30 in any of the said Example 1 thru | or Example 4. With this configuration, it is possible to further reduce the unevenness of the exhaust gas when introduced into the oxidation catalyst 4 or the filter 5 by the communication hole 55.

  8A and 9, the exhaust gas discharged from the engine passes through the exhaust manifold and is introduced into the exhaust introduction pipe 6 having one end connected to the exhaust manifold. The other end of the exhaust introduction pipe 6 is inserted so that the introduction chamber 2 and the central axis substantially coincide with each other. A rectifying plate 60 is provided between the introduction chamber 2 and the purification chamber 30 to partition the chamber. A plurality of passage holes 65 are opened in the rectifying plate 60, and the number of passage holes 65 is smaller toward the center side of the introduction chamber 2 and larger toward the outer peripheral side.

  With the above-described configuration, the exhaust gas discharged from the exhaust introduction pipe 6 has a small number of passage holes 65 in the portion that directly contacts the rectifying plate 60. Therefore, the exhaust gas discharge amount on the center side is suppressed, and the surrounding passage holes 65 However, since the number of passage holes 65 is large, the downstream side of the rectifying plate 60 can be introduced almost uniformly into the oxidation catalyst 4 and the filter 5. As a result, the performance of the oxidation catalyst 4 can be exhibited sufficiently, and runaway combustion or the like can be avoided. When the introduction chamber 2 of the present invention is compared with the conventional tapered introduction chamber, the length in the central axis direction can be shortened, and the overall length of the exhaust gas purification apparatus 1 can be shortened. The passage hole 65 provided in the current plate 60 can be easily opened by drilling or punching.

  8B and 9, Example 8 is inserted with the introduction chamber 2 and the central axis substantially coincided with each other, like the exhaust introduction pipe 6 of Example 7, and the introduction chamber 2 and the purification chamber 30 are separated from each other. A current plate 60 is provided between them. A plurality of passage holes 65 are opened in the rectifying plate 60 at substantially constant intervals, and the opening area of the passage holes 65 is reduced toward the center of the introduction chamber 2 and is increased toward the outer periphery.

  With the above configuration, the exhaust gas discharged from the exhaust introduction pipe 6 has a small opening area of the passage hole 65 in the portion that directly contacts the rectifying plate 60, so that the exhaust gas discharge amount on the center side is suppressed, and the surrounding passage holes However, since the opening area of the passage hole 65 is large, it can be introduced almost uniformly into the oxidation catalyst 4 and the filter 5 on the downstream side of the rectifying plate 60. Thereby, the performance of the oxidation catalyst 4 can be exhibited sufficiently, and runaway combustion or the like can be avoided. When the introduction chamber 2 and the conventional tapered introduction chamber are compared, the length in the central axis direction can be shortened, and the overall length of the exhaust gas purification apparatus 1 can be shortened. Further, it is possible to easily obtain substantially uniformity by simply changing the size of the passage hole. However, the rectifying plate 60 may be provided in the opening 6 a at the end of the exhaust introduction pipe 6. With this configuration, the exhaust gas discharged from the rectifying plate 60 is gradually diffused up to the oxidation catalyst 4 and can be made substantially uniform on the downstream side (space 30a) of the introduction chamber 2. it can.

  10 and 11A, the exhaust gas discharged from the engine passes through the exhaust manifold and is introduced into the exhaust introduction pipe 6 having one end connected to the exhaust manifold. The other end of the exhaust introduction pipe 6 is inserted so as to substantially coincide with the central axis of the introduction chamber 2. The tip of the exhaust introduction pipe 6 in the introduction chamber 2 is closed by a bottom plate, and a plurality of discharge holes 6 b of the same size are opened on the outer periphery of the exhaust introduction pipe 6 in the introduction chamber 2. The number of the discharge holes 6b is smaller on the side of the oxidation catalyst 4 and is increased as the distance from the oxidation catalyst 4 increases.

  With the above-described configuration, the exhaust gas from the exhaust introduction pipe 6 is exhausted more on the upstream side and less on the downstream side, and bypasses the end of the exhaust introduction pipe 6 on the downstream side of the introduction chamber 2. This makes it possible to make the exhaust gas substantially uniform in the space 30 a and introduce it into the oxidation catalyst 4 and the filter 5 substantially uniformly. The performance of the oxidation catalyst 4 and the filter 5 can be fully exerted to avoid runaway combustion. Further, when the introduction chamber 2 of the present invention and the conventional tapered introduction chamber 2 are compared, the length in the central axis direction can be shortened, and the overall length of the exhaust gas purification device 1 can be shortened. The exhaust hole 6b of the exhaust introduction pipe 6 can be easily opened by a drill or the like.

  10 and 11 (b), one end of the exhaust introduction pipe 6 is connected to the exhaust manifold, and the other end of the exhaust introduction pipe 6 is inserted so as to substantially coincide with the central axis of the introduction chamber 2. The tip of the exhaust introduction pipe 6 in the chamber 2 is closed by a bottom plate, and a plurality of exhaust holes 6 b are opened on the outer periphery of the exhaust introduction pipe 6 in the introduction chamber 2. The opening area of the discharge hole 6b is made smaller toward the oxidation catalyst 4 side and larger as it goes away from the oxidation catalyst 4.

  With the above-described configuration, the exhaust gas from the exhaust introduction pipe 6 is exhausted more on the upstream side and less on the downstream side, and bypasses the end of the exhaust introduction pipe 6 on the downstream side of the introduction chamber 2. This makes it possible to make the exhaust gas substantially uniform in the space 30 a and introduce it into the oxidation catalyst 4 and the filter 5 substantially uniformly. The performance of the oxidation catalyst 4 and the filter 5 can be fully exerted to avoid runaway combustion. Further, when the introduction chamber 2 of the present invention is compared with the conventional tapered introduction chamber, the length in the central axis direction can be shortened, and the overall length of the exhaust gas purification apparatus 1 can be shortened. In addition, substantially uniform uniformity can be easily obtained simply by changing the size of the opening area of the exhaust hole 6b of the exhaust introduction pipe 6 with a drill or the like. However, in the ninth and tenth embodiments, when the amount of the exhaust gas on the center side is small, a discharge hole is appropriately opened in the bottom plate.

1 Exhaust gas purification device 2 Introduction chamber 4 Oxidation catalyst 5 Filter (DPF)
6 Exhaust pipe 6b Exhaust hole 30 Purification chamber 60 Current plate 65 Passage hole

Claims (4)

  In an exhaust gas purification apparatus having a purification chamber configured by storing an oxidation catalyst for purifying exhaust gas and a filter in a case, an exhaust gas introduction chamber is formed in the case, and an exhaust introduction pipe is provided in the introduction chamber. A plurality of discharge holes are provided in the exhaust introduction pipe, and the number of the discharge holes is made different between the center position and the outer peripheral side position of the introduction chamber. An exhaust gas purifying apparatus characterized in that the exhaust gas purifier is more at the center and less at the outer peripheral side of the introduction chamber.   The case is provided with a rectifying plate that partitions the purification chamber and the introduction chamber, and a plurality of passage holes are provided in the rectification plate, the number of the passage holes being different between the center position and the outer peripheral side position of the introduction chamber, 2. The exhaust gas purifying apparatus according to claim 1, wherein the exhaust gas purifying apparatus has a smaller number in the center position and a larger number in the outer peripheral side of the introduction chamber.   3. The exhaust gas purifying apparatus according to claim 1, wherein an opening area of the exhaust hole of the exhaust introduction pipe is different between a center position of the introduction chamber and an outer peripheral side position.   4. The exhaust gas purifying apparatus according to claim 2, wherein an opening area of a rectifying plate that partitions the purification chamber and the introduction chamber is different between a center position and an outer peripheral side position of the introduction chamber.

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