JP2011033011A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact exhaust emission control device of an internal combustion engine enabling the entire part thereof to be easily mounted on a vehicle at a specified position even if the device is increased in size due to an increase in cleanup function. <P>SOLUTION: This exhaust emission control device 15 includes a cylindrical muffler container 16 structured by continuously arranging a first cylindrical portion 18 disposed in the longitudinal direction of the chassis frame of a vehicle and a second cylindrical portion 19 disposed on the outside of the chassis frame in the lateral direction of the vehicle. A particulate filter 21 is stored in either the first cylindrical portion or the second cylindrical portion whichever is disposed on the upstream side, and a selective NOx catalyst 23 is stored in the cylindrical portion disposed on the downstream side. A reducer adding device 30 for adding a reducer into the exhaust gas is provided to a corner 20 where the first cylindrical portion and the second cylindrical portion are continuously arranged. Consequently, the exhaust emission control device can have a sufficient margin to the vehicle despite the compactness, and can sufficiently accept the other cleanup member accordingly. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine that purifies exhaust gas discharged from the internal combustion engine.

A truck (vehicle) equipped with a diesel engine (internal combustion engine) is equipped with an exhaust purification device that purifies exhaust gas discharged from the diesel engine. Such an exhaust purification apparatus has an addition type structure in which a reducing agent is added to and purified by exhausted exhaust gas.
Many of these reducing agent addition type exhaust gas purification apparatuses are diesel particulate filters (hereinafter referred to as DPF) that collect particulate tomatter (hereinafter referred to as PM) in a straight muffler container connected to the exhaust pipe of the engine. ) And a selective reduction type NOx catalyst (SCR catalyst) for selectively reducing NOx, and an aqueous urea solution as a reducing agent is injected into the exhaust gas from an upstream side of the SCR catalyst by an injection device (reducing agent addition device), A structure in which NOx in the exhaust gas is reduced by the SCR catalyst is used.

Usually, the exhaust emission control device is mounted in the vicinity of a chassis frame constituting the vehicle body of the truck, specifically, in an empty space in the vehicle wheel base below the main frame extending in the vehicle longitudinal direction of the chassis frame. .
By the way, the exhaust gas purification apparatus tends to require improvement in the exhaust gas purification rate. For this reason, recently, in addition to the essential DPF and SCR catalyst, purification members such as a pre-stage catalyst and a post-stage catalyst that enhance the purification performance tend to be contained in the muffler container.
Incidentally, the DPF, the SCR catalyst, and other purification members are arranged in order in the exhaust gas flow direction. For this reason, when these DPF and SCR catalysts are housed in other purifying members in a straight muffler container, the exhaust purifying device has a considerably long overall length. The required space cannot be secured, and the exhaust gas purification device may not be mounted.

  Therefore, as disclosed in Patent Document 1, the exhaust purification apparatus is divided into two parts, for example, an upstream part in which the DPF is accommodated and a downstream part in which the SCR catalyst is accommodated, and these are connected by an intermediate pipe. A split type has been adopted to facilitate mounting on a vehicle. In this split type exhaust purification device, for example, an upstream portion is mounted below the chassis frame that becomes an empty space in the wheel base, and a downstream portion is mounted below the chassis frame that becomes an empty space of the vehicle rear overhang. Thus, the main body is dispersed in each part of the vehicle.

JP 2008-127997 A

However, in the case of a split-type exhaust purification device, there are a plurality of places to be mounted on the vehicle, and the way of piping the intermediate pipe tends to be different depending on the vehicle. Become. From the viewpoint of ease of mounting, it is hoped that the entire exhaust emission control device can be mounted compactly at a specific location (one location) of the vehicle that is not distributed but constant. There is a need for improvement.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a compact exhaust gas purification apparatus for an internal combustion engine that can be easily mounted in a specific place of a vehicle even if it is increased in size by improving the purification function.

  In order to achieve the above object, the first aspect of the present invention provides a first tubular portion disposed in the front-rear direction of the chassis frame of the vehicle and a second tubular portion disposed on the outside in the vehicle width direction from the chassis frame. And a cylindrical muffler container configured to be connected to each other, and a particulate filter is accommodated in a cylindrical portion disposed upstream of the first cylindrical portion and the second cylindrical portion, and the downstream side The selective-type NOx catalyst is housed in a cylindrical portion disposed in the cylinder, and a reducing agent addition device for adding a reducing agent to the exhaust gas is provided at the corner where the first cylindrical portion and the second cylindrical portion are connected. It was adopted.

  According to this configuration, the entire exhaust emission control device can be a compact integrated structure that only occupies a portion of the vehicle chassis frame in the front-rear direction and the chassis frame outside in the vehicle width direction. In addition, since the exhaust purification device is mounted on the chassis frame while partially protruding outward in the vehicle width direction, the first cylindrical portion disposed in the front-rear direction of the chassis frame is outside in the vehicle width direction. The entire length of the second cylindrical portion that protrudes to the surface is suppressed, and other catalysts can be sufficiently received. Further, the second cylindrical portion projecting in the vehicle width direction is also sufficiently allowed within the dimension from the chassis frame to the vehicle width direction end of the vehicle, so that it is possible to sufficiently receive another catalyst. For this reason, even if the exhaust purification device is increased in size (elongation of the entire length) by improving the purification function, the exhaust purification device remains compact and is mounted at a specific location (one location) of the vehicle.

According to the second aspect of the present invention, the first cylindrical portion is formed below the main frame member extending along the vehicle front-rear direction of the chassis frame so that the exhaust purification device can be mounted in the same operation in any vehicle. It was supposed to be arranged.
According to a third aspect of the present invention, the muffler container can be divided from the corner portion where the first cylindrical portion and the second cylindrical portion are continuous so that the exhaust purification device can be easily assembled.

  In the invention of claim 4, the corner portion where the first cylindrical portion and the second cylindrical portion are continuous so that mixing of the additive and the exhaust gas can be satisfactorily performed at the corner portion of a limited size, The reducing agent addition device has a cylindrical member for converging once exhaust gas from the upstream cylindrical portion is converged and led to the downstream cylindrical member. The reducing agent was sprayed from the end onto the converged exhaust gas flow in the cylindrical member.

According to the first aspect of the present invention, the exhaust emission control device only needs to occupy a part of the front-rear direction below the chassis frame of the vehicle and the outside of the chassis frame in the vehicle width direction. The influence on the arrangement of objects can be suppressed.
Therefore, even if the exhaust purification device is increased in size due to the improvement of the purification function (the entire length is extended), the exhaust purification device remains mounted in a specific location (one location) of the vehicle, such as in the vehicle wheelbase. This makes it possible to improve the bodywork and achieve many effects.

According to the second aspect of the present invention, the exhaust emission control device can be mounted in any vehicle by the same operation.
According to the invention of claim 3, the exhaust emission control device is further easily assembled.
According to the invention of claim 4, the exhaust emission control device can mix the additive and the exhaust gas satisfactorily at the corners of the limited space, and the additive can be sufficiently converted into the exhaust gas even with a curved unique structure. Can be mixed.

The top view which shows the exhaust gas purification apparatus which concerns on the 1st Embodiment of this invention with the vehicle carrying the apparatus. The perspective view which shows the whole exhaust gas purification apparatus. FIG. 3 is a plan sectional view taken along line AA in FIG. 2. Sectional drawing which shows the structure which mixes the reducing agent used as the principal part of the 2nd Embodiment of this invention, and waste gas.

The present invention will be described below based on the first embodiment shown in FIGS.
FIG. 1 shows a schematic cross section of a vehicle, for example, a truck. In FIG. 1, reference numeral 1 denotes a ladder-type chassis frame that extends in the vehicle front-rear direction constituting the vehicle body. The chassis frame 1 has a pair (two) of main frames 2 on both sides in the vehicle width direction. 3 is a front wheel provided on the front side of the main frame 2, 4 is a cabin, 5 is a diesel engine (corresponding to the internal combustion engine of the present application), 6 is a transmission connected to an output part of the diesel engine 5, Reference numeral 7 denotes a rear wheel provided on the rear side of the main frame 2, and reference numeral 8 denotes a loading platform mounted on the upper part of the main frame 2. The output portion of the transmission 6 is connected to the rear wheel 7 via the propeller shaft 9 and the rear differential 10.
The chassis frame 1 is provided with various incidental devices. Specifically, a fuel tank 11 is provided in the center of the main frame 2 on one side of the chassis frame 1. A battery 12 is provided at the front of the main frame 2 on the opposite side. Further, an exhaust purification device, for example, a urea addition type exhaust purification device 15 is provided at an empty place near the main frame 2, for example, at the center of the main frame 2. FIG. 2 shows the overall appearance of the exhaust purification device 15, and FIG. 3 shows the details of the exhaust purification device 15 (A-A line in FIG. 2).

  The exhaust purification device 15 will be described with reference to FIGS. 1 to 3. Reference numeral 16 denotes a muffler casing (corresponding to the muffler container of the present application). The muffler casing 16 is configured by a cylindrical casing member that extends elongated along the axial direction in which both ends are closed by the end walls 17, for example. This casing member is bent from the center, and has an L shape in which one side is longer than the other side. The long side of the muffler casing 16 is a casing portion 18 (corresponding to the first cylindrical portion of the present application) disposed here along the front-rear direction of the chassis frame 1. Here, the short side is defined in a casing portion 19 (corresponding to the second cylindrical portion of the present application) disposed outside the chassis frame 1 in the vehicle width direction. For example, the casing portion 19 is defined as a portion disposed on the upstream side of the exhaust purification device 15, and the casing portion 18 is defined as a portion disposed on the downstream side of the exhaust purification device 15.

  That is, as shown in FIG. 2 and FIG. 3, among the casing portions 18 and 19, except for the corner portion 20 where the casing portions 18 and 19 are connected, the straight casing portion 19 has particulate matter ( A diesel particulate filter 21 (hereinafter referred to as DPF 21) that collects PM) is housed together with a front-stage oxidation catalyst 22 (front-stage catalyst) that continuously regenerates the DPF 21, and an upstream muffler 25 mainly composed of the DPF 21 is provided. Forming. Note that an inlet portion 25 a into which exhaust gas flows is formed at the end of the upstream muffler 25. Similarly, in the straight casing portion 18 excluding the corner portion 20, an ammonia selective reduction type NOx catalyst 23 (hereinafter referred to as SCR catalyst 23), which is a selective reduction type NOx catalyst, is a rear stage that suppresses the ammonia flowing out from the SCR catalyst 23. A downstream muffler 26 mainly composed of the SCR catalyst 23 is formed by being housed together with the oxidation catalyst 24 (rear stage catalyst). Note that an outlet 26 a through which exhaust gas flows out is formed at the end of the downstream muffler 26. That is, in the present embodiment, in order to increase the purification rate, the structure in which the upstream muffler 25 is combined with the pre-stage oxidation catalyst 22 is used instead of the structure in which the DPF 21 and the SCR catalyst 23 are combined one by one. The muffler 26 has a structure in which two SCR catalysts 23 and a post-stage oxidation catalyst 24 are combined.

  As shown in FIGS. 2 and 3, for example, a urea injector 30 is provided as a reducing agent addition device at the corner 20 of the muffler casing 16 (upstream of the SCR catalyst 23). The urea injector 30 is connected to a urea supply unit (not shown) constituted by, for example, a urea tank or a urea supply pump, and the spray unit 30a at the front end faces the corner portion 20 from the spray unit 30a to the SCR catalyst 23. The urea aqueous solution is sprayed in a cone-shaped spray shape so that the urea aqueous solution can be mixed with the exhaust gas flowing in the corner portion 20. In particular, an aqueous urea solution is required to be well mixed with exhaust gas. Therefore, the corner 20 is devised to effectively mix the urea aqueous solution with the exhaust gas inside the limited corner 20. In this contrivance, a structure is used in which the exhaust gas flowing out from the DPF 21 is once converged in a predetermined manner and the urea aqueous solution is sprayed along the converged exhaust gas flow.

  Here, in the structure for converging the exhaust gas, for example, as shown in FIG. 2 and FIG. 3, an opening on the SCR catalyst 23 side in the corner portion 20 and an expansion chamber 33 in front of the inlet end of the SCR catalyst 23. A structure in which a converging pipe 36 (corresponding to a converging cylindrical member of the present application) for converging exhaust gas is used in the space on the DPF 21 side partitioned by a partition wall 35 is used. Specifically, for example, a pipe member in which a large number of slits 37 extending in the axial direction are formed in the peripheral wall is used as the converging pipe 36. This pipe member is disposed along the same direction as the axis of the downstream muffler 26 (SCR catalyst 23), and one end thereof is connected to an exhaust gas outlet 38 formed in the partition wall 35. The other end is attached to the wall surface of the corner 20, specifically, the wall 20 a opposite to the exhaust gas outlet 38, closes the same end, and exhaust gas from the DPF 21 enters the pipe member from the many slits 37. It is structured to flow into Thus, the exhaust gas that has passed through the DPF 21 is converged according to the passage in the pipe member while passing through the converging pipe 36, that is, while flowing out of the exhaust gas outlet 38 (end of the pipe member) from the slit 37.

  For spraying the urea aqueous solution, as shown in FIGS. 2 and 3, for example, the main body portion 30b of the urea injector 30 is installed on the outer surface of the wall portion 20a of the corner portion 20, and the spray portion 30a at the tip is moved from the wall portion 20a. A structure that faces the other end of the converging pipe 36 is used. In particular, the spray unit 30a is positioned so that the urea aqueous solution is injected into the converging pipe 36 in a cone-shaped spray shape. That is, the convergence pipe 36 is disposed so as to surround the entire sprayed urea aqueous solution. Thereby, the urea aqueous solution is sprayed all over from the cross-sectional direction of the converged exhaust gas flow, and further, the exhaust gas flows while surrounding the sprayed urea aqueous solution, and even in a short distance while passing through the convergence pipe 36, The aqueous solution and the exhaust gas are effectively mixed.

  Further, the muffler casing 16 has a structure that can be divided from the corner portion 20 as shown in FIGS. 2 and 3 so that the L-shaped exhaust purification device 15 can be easily assembled. Specifically, the casing portion 19 is divided between an inlet side portion of the DPF 21 and an inlet side portion of the corner portion 20, and the separated portions are detachably connected by a joint member, for example, a flange joint 40. is there. Further, the casing portion 19 on the outlet side of the DPF 21 opposite to the flange joint 40 sandwiching the DPF 21 is also divided by using a detachable structure using the flange joint 41 so that the maintenance of the DPF 21 can be easily performed.

  A downstream muffler 26 of the exhaust purification device 15 is disposed along the front-rear direction of the chassis frame 1, specifically, is disposed along the frame immediately below the main frame 2, and the upstream muffler 25 is disposed from the main frame 2. It is arranged to project outward in the vehicle width direction. The exhaust purification device 15 is fixed to each part of the main frame 2 and the chassis frame 1 by a fixing tool (not shown). Furthermore, the inlet portion 25a is connected to an exhaust pipe 5a extending from the diesel engine 5, and the outlet portion 26a is connected to an exhaust pipe 5b that goes to the atmosphere. As a result, the L-shaped exhaust purification device 15 is compactly mounted at a vacant place in the wheel base of the truck (between the front wheel 3 and the rear wheel 7), which is a specific place.

  Thus, the exhaust gas discharged from the diesel engine 5 is purified. That is, PM in the exhaust gas discharged from the diesel engine 1 is collected by the DPF 21 while being continuously regenerated (by the pre-stage oxidation catalyst 22). Next, when the exhaust gas flowing out from the DPF 21 passes through the corner portion 20, the exhaust gas is guided from the slit 37 into the converging pipe 36 and converged until reaching the exhaust gas outlet 38.

  On the other hand, the urea aqueous solution is sprayed from the spray portion 30 a of the urea injector 30 toward the passage in the converging pipe 36. As a result, the urea aqueous solution is sprayed so as to occupy the entire passage cross section of the converging pipe 36, and spreads over the entire exhaust gas flow that has converged. Moreover, since the exhaust gas flows so as to surround the sprayed urea aqueous solution from the surroundings, when the exhaust gas passes through the converging pipe 36, when the exhaust gas flows out from the exhaust gas outlet 38, the exhaust gas expands in the expansion chamber 33. At each stage, the exhaust gas and the exhaust gas are mixed, and the urea aqueous solution and the exhaust gas are sufficiently mixed even in the limited corner portion 20. By this mixing, the urea aqueous solution is hydrolyzed by the exhaust heat of the exhaust gas and the water vapor in the exhaust gas to generate ammonia. This ammonia is supplied to the SCR catalyst 23 through the expansion chamber 33. Then, NOx in the exhaust gas is reduced by the NOx reduction action in the SCR catalyst 23. Further, the ammonia flowing out from the SCR catalyst 23 is suppressed by the post-stage oxidation catalyst 24, and the exhaust gas after purification is discharged from the outlet portion 26a.

  With such an exhaust purification device 15, the entire exhaust purification device has a compact integrated structure that only occupies a part in the front-rear direction of the chassis frame 1 and a part on the outer side in the vehicle width direction from the chassis frame 1 as described above. That's okay. Moreover, since the exhaust purification device 15 is mounted in the chassis frame 1 with its end side protruding outward from the chassis frame 1 in the vehicle width direction, the downstream muffler 26 disposed in the vehicle longitudinal direction is The entire length of the casing portion 19 that extends outward in the direction is suppressed, and even when another catalyst such as the post-stage oxidation catalyst 24 is provided as shown in FIGS. Can be accepted. Further, the upstream muffler 25 arranged on the outer side in the vehicle width direction is also sufficiently allowed within the dimension from the main frame 2 (chassis frame 1) to the side end of the cargo bed 8 (the vehicle width direction end of the vehicle). As shown in FIGS. 2 and 3, even when another catalyst such as the post-stage oxidation catalyst 24 is provided, it can be sufficiently received.

Therefore, even if the exhaust purification device 15 is increased in size by increasing the purification function (lengthening the entire length), the exhaust purification device 15 maintains a compact size while maintaining a specific place (one place in the vehicle) such as a vacant place in the wheel base of the truck. ) Can be installed as a whole. As a result, the exhaust emission control device 13 can be easily mounted even on a vehicle having a short wheelbase, and an easy mounting work is required.
In particular, if the downstream muffler 26 is mounted below the main frame 2 of the chassis frame 1, the exhaust purification device 15 can be mounted by any similar operation in any truck (vehicle). If the muffler casing 16 can be divided from the corner portion 20, the assembly work of the exhaust purification device 15 becomes easy. In addition, if the portion having the DPF 21 can be divided, the maintenance of the DPF 21 can be easily performed.

  Further, since the exhaust gas flow toward the downstream side is converged at the corner portion 20 and the urea aqueous solution is sprayed from the base end of the converged exhaust gas flow, the urea aqueous solution is exhausted in the limited space such as the corner portion 20. The aqueous urea solution and the exhaust gas can be sufficiently mixed even with a unique casing structure that bends from the corner 20.

FIG. 4 shows a second embodiment of the present invention.
In the present embodiment, the exhaust gas is converged by using a pipe member having both ends opened normally instead of the pipe member having the slit as in the first embodiment. Specifically, as shown in FIG. 4, the pipe member 45 constituting the converging pipe 36 has one end connected to the exhaust gas outlet 38 of the partition wall 35, and the other end connected to the wall 20 a of the corner 20. The exhaust gas flows in through a gap between the wall portion 20a and the end of the pipe member. Of course, the pipe member is provided so as to surround the urea aqueous solution sprayed from the urea injector 30 as in the first embodiment.

Even in this way, the exhaust gas flowing out from the DPFP 21 can be converged, and the converged exhaust gas can be circulated while surrounding the urea aqueous solution sprayed from the urea injector 30, which is limited as in the first embodiment. The urea aqueous solution can be sufficiently mixed with the exhaust gas in the corner 20.
However, in FIG. 4, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Note that the present invention is not limited to one embodiment, and various modifications may be made without departing from the spirit of the present invention. For example, in one embodiment, a layout is shown in which an upstream muffler with a built-in DPF that tends to be shortened in the vehicle width direction is extended, but a layout in which a downstream muffler with a built-in SCR catalyst is extended in the vehicle width direction may be used. Further, the exhaust purification device may be, for example, a V shape instead of the L shape. In short, a muffler corresponding to the first cylindrical portion is arranged along the front-rear direction of the chassis frame, and corresponds to the second cylindrical portion. Any exhaust purification device having a shape in which the muffler is arranged from the chassis frame along the outer side in the vehicle width direction may be used.

1 Chassis frame 2 Main frame 5 Diesel engine (internal combustion engine)
15 Exhaust purification device 16 Muffler casing (muffler container)
18 Casing part (first cylindrical part)
19 Casing part (second cylindrical part)
20 Corner 21 Diesel particulate filter 22 Pre-stage oxidation catalyst 23 Ammonia selective reduction type NOx reduction catalyst (selective reduction type NOx catalyst)
24 Rear-stage oxidation catalyst 25 Upstream muffler 26 Downstream muffler 30 Urea injector (reducing agent addition device)
35 Bulkhead 36 Converging pipe (cylindrical member)
40, 41 Flange joint

Claims (4)

Exhaust gas discharged from an internal combustion engine comprising a first cylindrical portion arranged in the front-rear direction of a chassis frame of a vehicle and a second cylindrical portion arranged outside the chassis frame in the vehicle width direction. A cylindrical muffler container that circulates from one end to the other end;
A particulate filter housed in a tubular portion disposed upstream of the first tubular portion and the second tubular portion;
A selective NOx catalyst housed in a cylindrical portion disposed downstream of the first cylindrical portion and the second cylindrical portion;
A reducing agent addition device that is provided at a corner portion where the first cylindrical portion and the second cylindrical portion are connected, and adds a reducing agent required for the operation of the selective NOx catalyst in exhaust gas; An exhaust emission control device for an internal combustion engine.   2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the first cylindrical portion is disposed at a lower portion of a main frame extending along a vehicle longitudinal direction of a chassis frame of the vehicle.   The internal combustion engine according to claim 1 or 2, wherein the cylindrical muffler container can be divided from a corner portion where the first cylindrical portion and the second cylindrical portion are continuous. Exhaust purification equipment. The corner portion where the first cylindrical portion and the second cylindrical portion are connected is a convergence cylinder that once converges the exhaust gas from the upstream cylindrical portion and guides it to the downstream cylindrical portion. Having a shape member,
The said reducing agent addition apparatus sprays a reducing agent from the base end of the said cylindrical member into which the said waste gas flows in to the exhaust gas flow which converged in the said cylindrical member. The exhaust gas purification apparatus for an internal combustion engine according to any one of claims 3 to 4.

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