JP2018165477A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promote the mixture of injected urea water and an exhaust gas.SOLUTION: An exhaust emission control device of an internal combustion engine comprises: a first chamber 26; first and second passages 25, 27 which are connected to the first chamber while abutting thereon from the same direction, and arranged in parallel with each other; a filter 22 arranged in the first passage; and an injection valve 10 which is installed on a partitioning wall of the first chamber opposing the second passage, and injects liquid into the second passage. The exhaust emission control device is constituted so as to make an exhaust gas flowing out of the first passage flow into the second passage via the first chamber. The exhaust emission control device further comprises a drift current wall 48 which is installed in the first chamber, and biases the exhaust gas in the first chamber to a sideway with respect to a direction in which the gas progresses toward the second passage from the first passage. The drift current wall generates a vortex flow S2 of the exhaust gas in the second passage.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine, and more particularly to an exhaust gas purification apparatus mainly applied to a diesel engine.

  In the exhaust passage of the diesel engine, a filter that collects particulate matter in the exhaust and a selective reduction type NOx catalyst that reduces and removes NOx in the exhaust are sequentially provided from the upstream side. An injection valve for injecting urea water is provided downstream of the filter and upstream of the NOx catalyst. The NOx catalyst reduces NOx in the exhaust gas using ammonia derived from urea water injected from the injection valve as a reducing agent.

JP 2010-180726 A

  By the way, the following can be considered as a configuration of the exhaust purification device. That is, the first and second passages arranged in parallel to each other are connected to the first chamber by abutting from the same direction, a filter is installed in the first passage, and urea is passed from the injection valve toward the second passage. Spray water.

  It is desirable that the urea water injected from the injection valve is thoroughly mixed with the exhaust gas and homogenized. However, in the above configuration, an effective means for promoting the mixing of the urea water injected into the second passage and the exhaust gas has not been proposed yet.

  In Patent Document 1, the following configuration is adopted to promote mixing of urea water and exhaust gas. That is, the outlet chamber on the outlet side of the filter carrier that is parallel to the inlet chamber and the inlet chamber on the inlet side of the reduction catalyst carrier are communicated with each other by a communication pipe that extends perpendicularly to these axes and extends in an S shape, Inject urea water. The mixed flow of the exhaust gas and urea water that has entered the inlet chamber from the communication pipe is swirled in the inlet chamber to promote mixing. However, since the premise configuration of the configuration of Patent Document 1 is significantly different, it cannot be adopted in the above configuration.

  Accordingly, the present invention has been made in view of such circumstances, and an object thereof is to provide an exhaust purification device for an internal combustion engine that can promote mixing of injected urea water and exhaust gas.

According to one aspect of the invention,
A first chamber;
A first passage and a second passage which are connected to the first chamber by being abutted from the same direction and arranged in parallel to each other;
A filter installed in the first passage;
An injection valve installed on a partition wall of the first chamber facing the second passage and for injecting liquid into the second passage;
An exhaust purification device for an internal combustion engine comprising:
The exhaust purification device is configured to cause the exhaust gas flowing out from the first passage to flow into the second passage through the first chamber,
The exhaust purification device further includes a drift wall that is installed in the first chamber and biases the exhaust gas in the first chamber laterally with respect to the direction from the first passage toward the second passage,
The drift wall is configured to generate a swirling flow of exhaust gas in the second passage. An exhaust gas purification apparatus for an internal combustion engine is provided.

  Preferably, the drift wall is formed by a tubular member extending coaxially from the first passage and partitioning the first chamber, and the tubular member has at least one opening in a circumferential direction thereof, and With respect to a virtual plane including the first passage axis of one passage and the second passage axis of the second passage, the total area of the openings on one side is larger than the total area of the openings on the other side.

  Preferably, the tubular member is integrally formed with the outer tube of the filter.

  Preferably, a sensor is installed on the other side in the first chamber, on the radially outer side of the circumferential region where the opening of the tubular member is not present.

  Preferably, the sensor is a NOx sensor.

  Preferably, the filter is detachable by inserting and removing in the direction of the first passage axis of the first passage.

Preferably, the exhaust emission control device further includes a casing that houses or defines the first chamber and the first and second passages,
The casing includes a passage hole through which the filter passes when the filter is inserted and removed, and a detachable hole cover that closes the passage hole.

Preferably, the exhaust gas purification device further includes a selective reduction type NOx catalyst installed downstream of the second passage,
The injection valve is a urea water injection valve that injects urea water.

Preferably, the downstream end of the first passage and the upstream end of the second passage are abutted and connected to the first chamber,
The exhaust purification device includes:
A third passage disposed parallel to the second passage;
A second chamber in which the downstream end of the second passage and the upstream end of the third passage are abutted and connected from the same direction;
A fourth passage disposed parallel to the third passage;
A third chamber in which the downstream end of the third passage and the upstream end of the fourth passage are abutted and connected from the same direction;
Further comprising
The NOx catalyst is installed in the fourth passage.

Preferably, the exhaust purification device includes:
A first oxidation catalyst installed upstream of the filter in the first passage;
And a second oxidation catalyst installed downstream of the NOx catalyst in the fourth passage.

  According to the present invention, mixing of the injected urea water and the exhaust gas can be promoted.

1 is a perspective view showing an external appearance of an exhaust emission control device according to an embodiment of the present invention. It is a front view which shows the external appearance of an exhaust gas purification apparatus. It is a front perspective view which shows the internal structure of an exhaust gas purification apparatus. It is a back perspective view showing the internal structure of an exhaust emission control device. It is a front view which shows the internal structure of an exhaust gas purification apparatus. It is VI-VI sectional drawing of FIG. 5 which shows the internal structure of an exhaust gas purification apparatus. It is a disassembled perspective view which shows the structure around the fixing | fixed part of a filter. It is a front view which shows the flow of the exhaust gas in a 1st chamber. FIG. 7 is a cross-sectional view corresponding to IX-IX in FIG. 6 in a comparative example. It is a front view which shows the internal structure of the exhaust gas purification apparatus which concerns on other embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the following embodiment.

  1 and 2 show the appearance of an exhaust emission control device according to an embodiment of the present invention. An internal combustion engine (not shown, also referred to as an engine) to which an exhaust emission control device is applied is a diesel engine mounted on a vehicle. The vehicle (not shown) is a large vehicle such as a truck. However, the types and applications of the vehicle and the internal combustion engine are not limited. For example, the vehicle may be a small vehicle such as a passenger car, and the engine may be a gasoline engine.

  For convenience, the directions of the three orthogonal axes, that is, the respective directions of front, rear, left, right and up are defined as shown in the figure. However, it should be noted that these directions are merely defined for the convenience of explanation with respect to the illustrated arrangement.

  As shown in the figure, the exhaust emission control device 1 includes a sealed box-type casing 2 that accommodates members described later in a compact manner. The engine exhaust gas G is introduced into the casing 2 from the apparatus inlet pipe 3. The exhaust gas in the casing 2 after the purification treatment or the post-treatment is discharged from the apparatus outlet pipe 4 to the outside. An upstream exhaust pipe (not shown) is flange-connected to the apparatus inlet pipe 3, and a downstream exhaust pipe (not shown) is flange-connected to the apparatus outlet pipe 4.

  A sensor mounting recess 5 is provided at the front end of the right side surface of the casing 2, and a sensor insertion hole 6 is provided in the bottom surface of the sensor mounting recess 5. A sensor indicated by an imaginary line, in this embodiment, a NOx sensor 7 is fixedly attached to the bottom surface portion of the sensor mounting recess 5 with its tip detection portion inserted into the sensor insertion hole 6. In the mounted state, the NOx sensor 7 is accommodated in the sensor mounting recess 5 in an obliquely upward state. The NOx sensor 7 is a sensor for detecting the NOx concentration of the exhaust gas.

  An injection valve mounting recess 8 is provided in the upper right corner of the front end wall 19 that forms the front surface of the casing 2, and an injection valve insertion hole 9 is provided in the bottom surface of the injection valve mounting recess 8. The injection valve indicated by the phantom line, in this embodiment, the urea water injection valve (hereinafter simply referred to as the injection valve) 10 for injecting urea water is inserted into the injection valve insertion hole 9 at the tip portion having the injection hole, It is fixedly attached to the bottom surface of the injection valve mounting recess 8. In the mounted state, the injection valve 10 is disposed along the front-rear direction with the injection hole facing rearward, and the rear end portion is accommodated in the injection valve mounting recess 8.

  Moreover, the casing 2 has a passage hole through which the filter passes when a filter to be described later is inserted and removed, and a detachable hole cover 11 that closes the passage hole. These passage holes and hole cover 11 will be described later. The passage hole and the hole cover 11 are provided in the lower right portion of the front surface portion of the casing 2 and at a position below the injection valve mounting recess 8.

  Further, a convex portion 12 that defines a third chamber to be described later is provided on the upper left portion of the front surface portion of the casing 2. The convex portion 12 swells forward in a hill shape and is formed into a horizontally falling droplet shape. The casing 2 also has an outlet chamber defining part 13 to which the apparatus outlet pipe 4 is connected. The casing 2 is provided with a plurality (only two shown) of brackets 90 and 91 for attaching the exhaust purification device 1 to the vehicle body.

  Next, the internal structure of the casing 2 will be described with reference to FIGS. 3 and 4. 3 is a front perspective view, and FIG. 4 is a rear perspective view.

  As shown in the figure, inside the casing 2, four post-treatment members, that is, a first oxidation catalyst 21, a filter 22, a selective reduction type NOx catalyst 23, and a second oxidation catalyst 24 are disposed in the casing 2 or an exhaust purification device. 1 are provided in this order from the upstream side in the exhaust flow direction (indicated by arrows in the figure).

  The first oxidation catalyst 21 oxidizes and purifies unburned components (hydrocarbon HC and carbon monoxide CO) in the exhaust gas, and heats the exhaust gas with the reaction heat at this time.

  The filter 22 is a so-called diesel particulate filter (DPF: Diesel Particulate Filter) or a soot filter with a catalyst (CSF: Caterized Soot Filter), and is a continuous regenerative filter carrying a catalyst. The filter 22 is of a wall flow type, and collects particulate matter (hereinafter referred to as PM: Particulate Matter) contained in the exhaust gas, and continuously oxidizes the collected PM by catalytic reaction to remove it by combustion.

  A selective reduction type NOx catalyst (SCR: Selective Catalytic Reduction) 23 reduces and removes NOx in the exhaust gas using ammonia derived from urea water injected from the injection valve 10 as a reducing agent.

  The second oxidation catalyst 24 is also referred to as an ammonia slip oxidation catalyst, and oxidizes and removes excess ammonia discharged (slipped) from the NOx catalyst 23.

  Further, in the casing 2, a first passage 25, a first chamber 26, a second passage 27, a second chamber 28, a third passage 29, a third chamber 30, and a fourth passage 31 through which exhaust gas flows respectively. Are defined in this order from the upstream side. The first to fourth passages 25, 27, 29, 31 are formed inside a metal pipe (stainless steel pipe in this embodiment), and the first to third chambers 26, 28, 30 are made of metal containers (in this embodiment). (Stainless steel container). Hereinafter, the pipes that define the first to fourth passages 25, 27, 29, and 31 are referred to as first to fourth passage pipes, and the first to fourth passage pipes are represented by reference numerals 25A, 27A, 29A, and 31A, respectively. . A container that defines the first to third chambers 26, 28, and 30 is referred to as a first to third chamber container, of which the second chamber container is denoted by reference numeral 28A.

  The first to fourth passages 25, 27, 29, 31 are formed in a linear shape and a circular cross section, and the first and fourth passages 25, 31 have a larger diameter than the second and third passages 27, 29. The first oxidation catalyst 21 and the filter 22 are installed in series in the first passage 25, and the NOx catalyst 23 and the second oxidation catalyst 24 are installed in series in the fourth passage 31.

  Explaining schematically the flow of exhaust gas in the exhaust gas purification device 1, exhaust gas introduced into the device from the device inlet pipe 3 at the rear end of the device first flows in the first passage 25 from the rear to the front. Sometimes it passes through the first oxidation catalyst 21 and the filter 22 in order. Thereafter, the exhaust gas enters the first chamber 26 at the front end of the apparatus, passes through the first chamber 26 generally upward, and enters the second passage 27. At this time, the exhaust gas is U-turned from the front to the rear. The exhaust gas flows from the front to the rear in the second passage 27. Thereafter, the exhaust gas enters the second chamber 28 at the rear end of the apparatus, passes through the second chamber 28 sideways, and enters the third passage 29. At this time, the exhaust gas is U-turned from the rear to the front. The exhaust gas flows in the third passage 29 from the rear to the front. Thereafter, the exhaust gas enters the third chamber 30 at the front end of the apparatus, passes through the third chamber 30 in a substantially lateral direction, and enters the fourth passage 31. At this time, the exhaust gas is U-turned from the front to the rear. Then, the exhaust gas flows from the front to the rear in the fourth passage 31 and at this time passes through the NOx catalyst 23 and the second oxidation catalyst 24 in order. Thereafter, the exhaust gas passes through an outlet chamber 35 formed in the outlet chamber defining portion 13 and is discharged to the outside of the device through the device outlet pipe 4 at the rear end portion of the device.

  Next, details of each part will be described.

  The first passage 25 is disposed in the lower right portion of the apparatus and extends from the rear to the front along the exhaust flow direction. In the first passage 25, a portion upstream or rearward of the first oxidation catalyst 21 is an inlet chamber 32. Exhaust gas is introduced into the inlet chamber 32 from the aforementioned apparatus inlet pipe 3. A bulging portion 33 and an inlet opening 34 composed of a large number of holes are provided at a connection portion between the inlet chamber 32 and the apparatus inlet pipe 3. The bulging portion 33 is attached to the outer peripheral surface of the first passage pipe 25A. The apparatus inlet pipe 3 is attached to and communicated with the bulging portion 33. The inlet opening 34 is provided by opening a part of the first passage pipe 25 </ b> A, communicates the inside of the bulging part 33 and the inlet chamber 32, and passes the exhaust gas that has entered the bulging part 33 from the apparatus inlet pipe 3. And introduced into the entrance chamber 32.

  As shown in FIG. 5, the first chamber 26 is formed on the right side of the front end portion of the apparatus so as to extend substantially vertically. The first chamber 26 is located between the plate-like partition wall 36 that partitions the interior of the casing 2 forward and backward, the front end wall 19 (see FIGS. 1 and 2) of the casing 2, and the partition wall 36 and the front end wall 19. The plate-like first peripheral wall 37 connected to these is defined as a substantially sealed space. The partition wall 36, the front end wall 19 and the first peripheral wall 37 constitute most of the first chamber container. The first peripheral wall 37 is formed so as to surround the downstream end of the first passage 25 and the upstream end of the second passage 27. The first peripheral wall 37 is formed in a step shape on the right side, and a sensor mounting hole 38 is provided in the step portion. The tip detection portion 7A of the NOx sensor 7 is inserted into the sensor insertion hole 38 after being inserted into the sensor insertion hole 6 of the casing 2, and is attached in an airtight state. The tip detector 7A of the NOx sensor 7 is exposed in the first chamber 26 at a position radially outward of the first passage 25 and obliquely to the right.

  The second passage 27 is disposed in the upper right portion of the apparatus and extends from the front to the rear along the exhaust flow direction. The second passage 27 is disposed to be spaced diagonally to the upper right of the first passage 25 and is disposed in parallel to the first passage 25. The NOx catalyst 23 is not provided in the second passage 27, no post-processing member (catalyst, etc.) is provided, and the NOx catalyst 23 is provided downstream of the second passage 27. Should be noted.

  The first and second passages 25 and 27 are abutted and connected to the first chamber 26 from the same direction. That is, the downstream end of the first passage 25 and the upstream end of the second passage 27 are abutted and connected to the first chamber 26 located in front from the rear.

  The second chamber 28 is disposed at the rear end of the apparatus and directly above the first passage 25, and extends from the right side to the left side along the exhaust flow direction. The third passage 29 is disposed at the upper center of the apparatus and extends from the rear to the front along the exhaust flow direction. The third passage 29 is spaced apart from the left side of the second passage 27 and is disposed in parallel with the second passage 27.

  The second and third passages 27 and 29 are abutted and connected to the second chamber 28 from the same direction. That is, the downstream end of the second passage 27 and the upstream end of the third passage 29 are abutted and connected to the second chamber 28 located at the rear from the front.

  As shown in FIG. 5, the third chamber 30 is formed at the front end portion of the apparatus so as to extend substantially in the left-right direction, and is formed in the shape of a side-by-side droplet. Corresponding to the fact that the third passage 29 has a small diameter and the fourth passage 31 has a large diameter, the right side portion of the third chamber 30 where the third passage 29 opens has a small-diameter circular outline, and the fourth passage 31 has The left portion of the open third chamber 30 has a large-diameter circular contour. The third chamber 30 is positioned between the partition wall 36 described above, the front end wall 19 of the casing 2 described above, in particular, the convex portion 12 (see FIGS. 1 and 2), and the partition wall 36 and the front end wall 19. The plate-like second peripheral wall 39 connected to these is defined as a substantially sealed space. The partition wall 36, the front end wall 19 and the second peripheral wall 39 form a third chamber container. The second peripheral wall 39 is formed so as to surround the downstream end of the third passage 29 and the upstream end of the fourth passage 31. The third chamber 30 is adjacent to the first chamber 26, and the first peripheral wall 37 and the second peripheral wall 39 are shared at the adjacent portion. Only part of the front end portion of the NOx catalyst 23 protrudes into the third chamber 30, but even in this way, a convex portion is formed on the front end wall 19 of the casing 2 so that the exhaust gas uniformly strikes the entire front portion of the NOx catalyst 23. 12 is provided. The convex portion 12 secures a sufficient space for the exhaust gas to flow between the front surface portion of the NOx catalyst and the casing front end wall 19.

  The fourth passage 31 is disposed in the upper left portion of the apparatus and extends from the front to the rear along the exhaust flow direction. The fourth passage 31 is spaced apart from the left side of the third passage 29 and is disposed in parallel with the third passage 29. At a position downstream or rearward of the second oxidation catalyst 24, the fourth passage pipe 31 </ b> A is cut out at approximately half in the circumferential direction and communicated with the outlet chamber 35. The outlet chamber defining part 13 and the outlet chamber 35 are formed in the lower left part of the apparatus. The apparatus outlet pipe 4 communicates with the outlet chamber 35 and protrudes rearward from the outlet chamber defining portion 13.

  The third and fourth passages 29 and 31 are abutted and connected to the third chamber 30 from the same direction. That is, the downstream end of the third passage 29 and the upstream end of the fourth passage 31 are abutted and connected to the third chamber 30 located in front from the rear.

  By the way, the filter 22 of this embodiment can be attached or detached by inserting and removing from the front of the apparatus in the front-rear direction. Therefore, the structure regarding this is demonstrated below.

  6 is a cross-sectional view taken along the line VI-VI in FIG. It is a figure which shows the cross-sectional structure at the time of cut | disconnecting by the virtual plane P. FIG. FIG. 7 is an exploded perspective view showing the structure around the fixed portion of the filter 22. Note that FIG. 6 is a schematic diagram in which necessary portions are exaggerated and drawn in an easy-to-understand manner, and it should be noted that the illustrated dimensions, scales, relative arrangements, and the like do not necessarily match the actual objects.

  As shown in the figure, the first passage axis C1 and the second passage axis C2 are parallel, and therefore the first passage 25 and the second passage 27, and the first passage tube 25A and the second passage tube 27A are parallel. The first passage pipe 25 </ b> A is coupled to the partition wall 36 at the front end position thereof, and a first chamber 26 is defined between the partition wall 36 and the casing front end wall 19. The second passage pipe 27A is also coupled to the partition wall 36 at the front end position thereof. A curved portion 40 is formed in the partition wall 36 around the entrance of the second passage 27 so that the exhaust gas can be smoothly introduced from the first chamber 26 into the second passage 27.

  The injection valve 10 is mounted in the injection valve mounting recess 8 of the casing front end wall 19 coaxially or substantially coaxially with the second passage axis C2. The tip end portion 42 having the injection hole 41 of the injection valve 10 is inserted from the front into the injection valve insertion hole 9 of the injection valve mounting recess 8 and is exposed in the first chamber 26. The injection valve 10 injects urea water U from the injection hole 41 toward the second passage 27 in the direction of the second passage axis C2. In other words, the nozzle hole 41 is oriented in the direction of the second passage axis C2.

  The injected urea water U is first mixed with the exhaust gas in the second passage 27. Next, in the process in which the exhaust gas flows from the second passage 27 to the fourth passage 31, the urea water U and the exhaust gas are further mixed, and the air-fuel mixture is finally supplied to the NOx catalyst 23. Thus, since the urea water U is mixed with the exhaust gas through a relatively long path, mixing of both can be promoted.

  The casing front end wall 19 that forms the injection valve mounting recess 8 forms a partition wall of the first chamber 26 that faces the second passage 27. Since the injection valve mounting recess 8 is recessed toward the second passage 27 at a position opposite to the second passage 27, the exhaust gas is guided along this, and the exhaust gas from the first chamber 26 to the second passage 27. Is easy to introduce. However, the injection valve mounting recess 8 may be omitted.

  In the first passage pipe 25A, a first oxidation catalyst 21 is installed on the upstream side, that is, the rear side, and a filter 22 is coaxially installed on the downstream side, that is, the front side. The first oxidation catalyst 21 and the filter 22 are made of metal (stainless steel in the present embodiment) outer tubes 43 and 44 positioned in the outermost peripheral portion, and fixed in the outer tubes 43 and 44, such as Pt. Ceramic supports 45 and 46 each carrying a noble metal are integrally provided. The outer tube 43 of the first oxidation catalyst 21 is fitted and fixed in the first passage tube 25A so as not to be removed. On the other hand, the outer tube 44 of the filter 22 is fitted in the first passage tube 25A so as to be slidable back and forth.

  The position of the front surface of the filter carrier 46 in the front-rear direction substantially matches the position of the downstream end of the first passage 25, that is, the position of the partition wall 36. On the other hand, the filter outer tube 44 extends forward from the filter carrier 46, passes through the first chamber 26, passes through the passage hole 47 provided in the casing front end wall 19, and is forward of the passage hole 47. Extends to position. This extension portion extends from the first passage 25 coaxially to form a tubular member 48 that partitions the first chamber 26. The tubular member 48 is formed in a tubular shape having a circular cross section.

  As shown also in FIG. 5, the tubular member 48 has at least one circumferential portion, in the present embodiment, a plurality of openings, that is, communication holes 49. Through the communication holes 49, the first passage 25 and the first chamber 26 are substantially communicated with each other. The front end of the tubular member 48 is integrally formed with a flange portion 52 that protrudes outward in the radial direction.

  The casing front end wall 19 is integrally formed with a cylindrical portion 50 that protrudes forward and defines a passage hole 47 and a flange portion 51 that protrudes from the front end of the cylindrical portion 50 outward in the radial direction.

  The front end opening of the tubular member 48 is closed by the hole cover 11 described above. Thus, the first passage 25 and the first chamber 26 are closed from the outside, and the first passage 25 and the first chamber 26 are separated from each other by the tubular member 48 except for the communication hole 49. In the hole cover 11, the central portion facing the front end opening of the tubular member 48 bulges slightly forward. A flange portion 53 that is superimposed on the flange portion 52 is integrally formed on the outer peripheral side of the central portion.

  A ring-shaped first metal gasket 54 is interposed between the flange portion 51 of the casing front end wall 19 and the flange portion 52 of the filter outer tube 44. A ring-shaped second metal gasket 55 is interposed between the flange portion 52 of the filter outer tube 44 and the flange portion 53 of the hole cover 11. On the rear rear side of the flange portion 51 of the casing front end wall 19, a half ring-shaped rear flange 56 that is divided into two parts in the vertical direction is superimposed. On the front front side of the flange portion 53 of the hole cover 11, a ring-shaped (or half-ring-shaped) front flange 60 is superimposed. These are all overlapped and bolted, so that they are fixed to the casing 2 at once.

  On the other hand, a ring-shaped receiving portion 58 for fitting and receiving a ring-shaped expanded graphite gasket 57 from the front is provided on the front end surface portion of the first passage pipe 25A coupled to the partition wall 36. The expanded graphite gasket 57 is fitted in advance on the outer peripheral portion of the filter outer tube 44. In the assembled state, the expanded graphite gasket 57 is sandwiched between the ring-shaped flange portion 59 formed on the outer peripheral portion of the filter outer tube 44 and the receiving portion 58 and pressed against the receiving portion 58 by the flange portion 59. Thereby, it is possible to prevent PM from leaking into the first chamber 26 from the gap between the first passage pipe 25 </ b> A and the filter outer pipe 44.

  As shown in FIG. 7, a plurality of mounting bolts 61 are inserted rearwardly into a plurality of bolt insertion holes (not shown) of the front flange 60. These mounting bolts 61 are sequentially inserted from the front into a plurality of bolt insertion holes 53H, 55H, 52H, 54H, 51H corresponding to the flange portion 53, the second metal gasket 55, the flange portion 52, the first metal gasket 54, and the flange portion 51. It is inserted. The mounting bolts 61 are tightened into the corresponding female screw holes 56H of the rear flange 56. As a result, the plurality of superimposed members are collectively fixed and supported on the flange portion 51.

  Further, in order to position each member for easy assembly, a plurality of (two in this embodiment) positioning bolts 62 are fixed to the rear flange 56 in a forward direction. The positioning bolts 62 have a plurality of positioning bolt insertion holes 51K, 54K, 52K, 55K corresponding to the flange portion 51, the first metal gasket 54, the flange portion 52, the second metal gasket 55, the flange portion 53, and the front flange 60. 53K (the front flange 60 is not shown) is inserted sequentially from the rear, and each member is positioned before the mounting bolt 61 is mounted. Then, the nut 62 is tightened into the male screw portion of the positioning bolt 62 protruding from the positioning bolt insertion hole of the front flange 60. Each member is also fixed to the flange portion 51 at the fastening portion of the nut 62 and the positioning bolt 62.

  Thus, when the filter 22 is attached, the expanded graphite gasket 57 is naturally pressed against the receiving portion 58 by the flange portion 59, and the gap between the first passage tube 25A and the filter outer tube 44 is sealed.

  Here, a method for attaching and removing the filter 22 will be briefly described. With respect to the mounting method, the upper rear flange 56 is arranged on the rear rear side of the flange portion 51, and the positioning bolt 62 is inserted into the positioning bolt insertion hole 51K of the flange portion 51 and protrudes forward. Next, the positioning bolt insertion hole 54K of the first metal gasket 54 is fitted into the protruding portion of the positioning bolt 62 from the front, and the first metal gasket 54 is attached.

  Next, the expanded graphite gasket 57 is attached to the filter 22 from the rear, and the filter 22 is inserted into the passage hole 47 from the front, and then slid into the first passage pipe 25A. At the same time, the positioning bolt insertion hole 52K of the filter 22 is fitted to the positioning bolt 62.

  Next, the positioning bolt insertion hole 55K of the second metal gasket 55 is fitted to the positioning bolt 62, the positioning bolt insertion hole 53K of the hole cover 11 is fitted to the positioning bolt 62, and the positioning bolt insertion hole of the front flange 60 is positioned. The nut 62 is temporarily fitted to the positioning bolt 62 by fitting with the bolt 62. As a result, each component is roughly positioned.

  Next, the lower rear flange 56 is disposed on the rear rear side of the flange portion 51, and the plurality of mounting bolts 61 are sequentially inserted from the front into the bolt insertion holes of the respective parts while being held by hands so as not to fall. The flange 56 is tightened into the female screw hole 56H. Finally, by tightening the nut 62, the attachment of the filter 22 is completed. Simultaneously with the completion of the attachment, the expanded graphite gasket 57 is brought into close contact with the flange portion 59 and the receiving portion 58 to seal the gap.

  About the removal method of the filter 22, it is possible to remove the filter 22 by performing the procedure reverse to the above. Thus, the filter 22 can be attached and detached by inserting and removing it from the front of the apparatus in the front-rear direction. Thereby, when the filter 22 cannot be regenerated by engine control, the filter 22 can be removed and regenerated outside. If the filter 22 deteriorates so that it cannot be regenerated, the filter 22 can be removed and replaced.

  A structure similar to the structure shown in FIG. 6 is applied to other passages and chambers.

  Next, the tubular member 48 which is a characteristic part of this embodiment will be described. In FIG. 5, the tubular member 48 is exaggerated.

  As shown in FIGS. 5 and 6, the tubular member 48 partitions the first chamber 26 into an inner region 65 that is an inner region of the tubular member 48 and an outer region 66 that is an outer region of the tubular member 48. . The exhaust gas that has passed through the filter carrier 46 in the first passage 25 enters the inner region 65, passes through the communication hole 49, enters the outer region 66, and then enters the second passage 27.

  As shown by the arrows in FIG. 8, in the first chamber 26, the exhaust gas is generally directed from the first passage 25 toward the second passage 27, specifically from the first passage axis C1 to the second passage axis C2. It flows in the direction (called the main direction). However, in this embodiment, the exhaust gas in the first chamber 26 is simultaneously biased laterally with respect to the main direction. It is the tubular member 48 that does this. The tubular member 48 corresponds to a drift wall referred to in the claims.

  More specifically, the tubular member 48 is provided with a plurality (five in the present embodiment) of communication holes 49. The plurality of communication holes 49 include a first communication hole 49A, a second communication hole 49B, a third communication hole 49C, a fourth communication hole 49D arranged in order counterclockwise in FIG. A fifth communication hole 49E is included. These communication holes 49 are squares with rounded corners in this embodiment, but may have other shapes.

  49 A of 1st communicating holes are arrange | positioned at the top part of the tubular member 48, and have the largest perimeter, ie, angle length (alpha) 1. The second communication hole 49B has the smallest angular length α2. The third communication hole 49C has an intermediate angle length α3, the fourth communication hole 49C has a slightly smaller angle length α4, and the fifth communication hole 49C has an angle length α5 equal to the fourth communication hole 49C. Have. α1> α3> α4 = α5> α2. The order of the area (size) of each communication hole is the same as the order of the angular length.

  These communication holes 49 are arranged not at regular intervals in the circumferential direction but in an unbalanced manner. Here, when the left region L and the right region R are defined with respect to the virtual plane P including the first passage axis C1 and the second passage axis C2, the total area of the communication holes 49 in the left region L is the right region R. The total area of the communication holes 49 is larger. Specifically, the left region L includes most of the first communication hole 49A and all of the second communication hole 49B, the third communication hole 49C, and the fourth communication hole 49C. The region R includes only a part of the first communication hole 49A and the fifth communication hole 49C.

  Therefore, as shown by the arrows in FIG. 8, the exhaust gas flows more in the left region L than in the right region R, and is biased to the left with respect to the main direction. Due to this flow rate difference, a gentle clockwise swirl flow S1 is generated in the first chamber 26.

  When the drifting exhaust gas having the swirl flow S1 enters the second passage 27, a swirl flow S2 around the second passage axis C2 is generated in the second passage 27. Thus, the tubular member 48 is configured to generate the swirl flow S2 of the exhaust gas in the second passage 27. Since urea water is injected from the injection valve 10 into the swirling flow S2, the injected urea water is well stirred and mixed with the exhaust gas.

  Therefore, according to this embodiment, even in the configuration in which the first and second passages 25 and 27 are abutted and connected to the first chamber 26 from the same direction, the urea water and the exhaust gas injected into the second passage 27 Mixing can be significantly accelerated.

  Here, the advantages of the present embodiment will be further described in comparison with a comparative example. In a comparative example (not shown), the tubular member 48 and the communication hole 49 are not provided, and the first chamber 26 is not partitioned at all. Thus, the exhaust gas simply enters the first chamber 26 from the first passage 25, passes through the first chamber 26, and enters the second passage 27.

  In this case, neither the swirl flow S1 in the first chamber 26 nor the swirl flow S2 in the second passage 27 is generated. Then, the urea water injected into the second passage 27 does not mix well with the exhaust gas, and the urea water tends to continue to hit a specific portion of the second passage pipe 27A locally. An example of this specific portion is indicated by a symbol X in FIGS.

  As shown in FIG. 9, when the urea water U continues to hit the inner wall of the specific portion X of the second passage pipe 27A locally, there arises a problem that the inner wall eventually corrodes or wears. Further, the urea water U hitting the inner wall flows down the wall surface and accumulates at the bottom of the pipe. Combined with the weak flow of the exhaust gas at the bottom of the pipe, the accumulated urea water U will eventually crystallize and become a solid white deposit T and accumulate at the bottom of the pipe. Then, the white deposit T decreases the passage area in the pipe, increases the passage resistance, and increases the back pressure of the engine. Further, when the white deposit T partially peels and reaches the downstream NOx catalyst 23, the NOx catalyst 23 is damaged.

  On the other hand, in this embodiment, since urea water can be mixed well with exhaust gas, it is possible to solve the above-described problems of the comparative example all at once. That is, it is possible to reliably suppress the local contact of urea water and the corrosive wear of the second passage pipe 27A, the generation of white deposit T, the increase in passage resistance and engine back pressure, and the damage to the NOx catalyst 23. .

  Further, as shown in FIGS. 5 and 8, a tip detection portion 7 </ b> A of the NOx sensor 7 is installed in the right region R. The tip detection unit 7A is installed on the outer side in the radial direction of a circumferential region (referred to as a non-hole region) where the communication hole 49 of the tubular member 48 is not provided. In the present embodiment, a non-hole region 63 having a relatively large angular length is formed between the first communication hole 49A and the fifth communication hole 49C, and the tip detection unit 7A is located radially outside the non-hole region 63. is set up.

  According to this, it is possible to prevent the exhaust gas coming out from the communication hole 49 to the outer region 66 from directly hitting the tip detection portion 7A in the substantially axial direction, and to suppress the detection error of the NOx sensor 7.

  On the other hand, a fifth communication hole 49C is provided in the right region R, and the tip detection unit 7A is installed in the middle of the exhaust gas path from the fifth communication hole 49C toward the second passage 27. Therefore, the exhaust gas can be reliably applied to the tip detection portion 7A from substantially the side, and the detection accuracy of the NOx sensor 7 can be improved.

  In addition, in the right region R, the tip detection unit 7A is installed in a recess 64 that is in the middle of the exhaust gas path from the fifth communication hole 49C toward the second passage 27 and is a recessed portion. Therefore, it is possible to suppress the urea water injected from the injection valve 10 from flowing backward and hitting the tip detection unit 7 </ b> A, which also leads to improvement in detection accuracy of the NOx sensor 7.

  Next, another embodiment of the present invention will be described. Note that the same or common parts as those in the basic embodiment described above are denoted by the same reference numerals in the drawing and description thereof is omitted. Hereinafter, differences from the basic embodiment will be mainly described.

  As shown in FIG. 10, in this embodiment, the tubular member 48 and the communication hole 49 are not provided, and the inside of the first chamber 26 is not partitioned. The downstream end of the filter 22 is located in the first passage 25. Therefore, the exhaust gas simply enters the first chamber 26 from the first passage 25, passes through the first chamber 26, and enters the second passage 27 as indicated by an arrow in the figure.

  In this embodiment, instead of the tubular member 48, a simpler drift plate 70 is provided in the first chamber 26 as a drift wall. The drift plate 70 is fixed to at least one of the first peripheral wall 37, the partition wall 36, and the casing front end wall 19 in the right region R, and protrudes from the right side portion of the first peripheral wall 37 toward the virtual plane P. The drift plate 70 is provided in the right region R where the NOx sensor 7 is installed in one of the right region R and the left region L in the middle of the exhaust path from the first passage 25 to the second passage 27. It is done. And the drift plate 70 gives resistance to the flow of the exhaust gas which goes to the main direction. In the present embodiment, the drift plate 70 is arranged along the stepped portion 71 of the first peripheral wall 37 on which the NOx sensor 7 is seated, but the installation position thereof can be changed.

  According to this, as shown by the arrows in the figure, in the process of exhaust gas from the first passage 25 to the second passage 27 in the first chamber 26, the drift plate 70 causes the entire exhaust gas to move to the left with respect to the main direction. Biased. And when this exhaust gas flows into the 2nd channel | path 27, the swirl | vortex flow S2 centering on the 2nd channel | path axis | shaft C2 is produced | generated in the 2nd channel | path 27 similarly to basic embodiment. Since the urea water is injected into the swirl flow S2, the injected urea water and the exhaust gas can be well stirred and mixed. Therefore, as in the basic embodiment, this embodiment can also promote the mixing of the injected urea water and the exhaust gas, and solve the above-mentioned problems caused by insufficient mixing.

  Further, since the drift plate 70 is arranged along the stepped portion 71, the flow of exhaust gas that hits the tip detection portion 7A of the NOx sensor 7 from the side can be strengthened, which is advantageous in improving the detection accuracy of the NOx sensor 7. . In addition, since the drift plate 70 is disposed in the middle of the exhaust path from the tip detection unit 7A toward the second passage 27 so as to block the path from the tip of the injection valve 10 to the tip detection unit 7A, the injection valve 10 It is possible to suppress the urea water injected from the backflow and hitting the tip detection unit 7A, which is advantageous in improving the detection accuracy of the NOx sensor 7.

  In addition, although the filter 22 of this embodiment is not detachable, it may be detachable.

  As mentioned above, although embodiment of this invention was described in detail, various embodiment of this invention can be considered variously.

  (1) For example, the opening provided in the tubular member 48 may be an opening other than the communication hole 49, for example, a notch. Further, at least one opening may be provided, and only one opening may be provided. The shape, size, number, and the like of the opening can be arbitrarily determined.

  (2) The tubular member may be a separate body from the filter outer tube, or may be fixed in the first chamber in a non-detachable manner. The filter may or may not be removable.

  (3) The sensor may be a sensor other than a NOx sensor, such as a PM sensor, a λ sensor, an oxygen sensor, an A / F sensor, a temperature sensor, or a pressure sensor.

  (4) The injection valve may not be a urea water injection valve that injects urea water. The injection valve may be an injection valve that injects any liquid (for example, fuel, other reducing agent, water, or the like) that is required to promote mixing with the exhaust gas.

  The configurations of the above-described embodiments can be combined partially or wholly unless there is a particular contradiction. The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Exhaust purification device 2 Casing 7 NOx sensor 10 Injection valve 11 Hole cover 19 Front end wall 21 First oxidation catalyst 22 Filter 23 Selective reduction type NOx catalyst 24 Second oxidation catalyst 25 First passage 26 First chamber 27 Second passage 28 Second 2 chamber 29 3rd channel | path 30 3rd chamber 31 4th channel | path 44 Outer tube 47 Passing hole 48 Tubular member (diffusion wall)
49 Communication hole (opening)
70 Drift plate (Drift wall)
C1 First passage axis C2 Second passage axis P Virtual plane L Left region R Right region

Claims (10)

A first chamber;
A first passage and a second passage which are connected to the first chamber by being abutted from the same direction and arranged in parallel to each other;
A filter installed in the first passage;
An injection valve installed on a partition wall of the first chamber facing the second passage and for injecting liquid into the second passage;
An exhaust purification device for an internal combustion engine comprising:
The exhaust purification device is configured to cause the exhaust gas flowing out from the first passage to flow into the second passage through the first chamber,
The exhaust purification device further includes a drift wall that is installed in the first chamber and biases the exhaust gas in the first chamber laterally with respect to the direction from the first passage toward the second passage,
The exhaust flow purification apparatus for an internal combustion engine, wherein the drift wall is configured to generate a swirling flow of exhaust gas in the second passage. The drift wall is formed by a tubular member extending coaxially from the first passage and partitioning the inside of the first chamber, and the tubular member has at least one opening in a circumferential direction of the first passage. The total area of the opening on one side is larger than the total area of the opening on the other side with respect to a virtual plane including the first path axis and the second path axis of the second path. An exhaust gas purification apparatus for an internal combustion engine as described. The exhaust purification device for an internal combustion engine according to claim 2, wherein the tubular member is integrally formed with an outer tube of the filter. The exhaust emission control device for an internal combustion engine according to claim 2 or 3, wherein a sensor is installed on the other side in the first chamber and radially outside a circumferential region where the opening of the tubular member is not present. . The exhaust gas purification apparatus for an internal combustion engine according to claim 4, wherein the sensor is a NOx sensor. The exhaust purification device for an internal combustion engine according to any one of claims 1 to 5, wherein the filter is detachable by being inserted and removed in a direction of a first passage axis of the first passage. A casing that houses or defines the first chamber and the first and second passages;
The exhaust purification device for an internal combustion engine according to claim 6, wherein the casing includes a passage hole through which the filter passes when the filter is inserted and removed, and a removable hole cover that closes the passage hole. Further comprising a selective reduction type NOx catalyst installed downstream of the second passage,
The exhaust purification device for an internal combustion engine according to any one of claims 1 to 7, wherein the injection valve is a urea water injection valve that injects urea water. The downstream end of the first passage and the upstream end of the second passage are abutted and connected to the first chamber,
The exhaust purification device includes:
A third passage disposed parallel to the second passage;
A second chamber in which the downstream end of the second passage and the upstream end of the third passage are abutted and connected from the same direction;
A fourth passage disposed parallel to the third passage;
A third chamber in which the downstream end of the third passage and the upstream end of the fourth passage are abutted and connected from the same direction;
Further comprising
The exhaust purification device for an internal combustion engine according to claim 8, wherein the NOx catalyst is installed in the fourth passage. A first oxidation catalyst installed upstream of the filter in the first passage;
The exhaust purification device for an internal combustion engine according to claim 9, further comprising a second oxidation catalyst installed downstream of the NOx catalyst in the fourth passage.

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