JP6798221B2 - Exhaust gas purification system - Google Patents

Description

The present invention relates to an exhaust gas purification system, and more particularly to an exhaust gas purification system for improving an exhaust gas purification ability.

An exhaust gas purification system for purifying engine exhaust gas has been proposed (see, for example, Patent Document 1). In this exhaust gas purification system, the exhaust gas introduced into the inside from the exhaust introduction path of the cap covering the opening of the storage pipe (casing) passes through the gap located between the inner peripheral surface of the storage pipe and the catalyst. It is configured so that the entire amount flows into the catalyst while being folded back at the bottom of the storage pipe.

Japanese Unexamined Patent Publication No. 2011-047349

By the way, as a measure for improving the purification capacity of the exhaust gas purification system, it is possible to increase the capacity of the exhaust gas purification device such as an oxidation catalyst, a collection filter, and a selective reduction catalyst. For example, in order to increase the capacity of any of the oxidation catalyst (DOC), selective reduction catalyst (SCR catalyst), and ammonia oxidation catalyst described in Patent Document 1, the diameter of the storage tube may be increased. It is necessary to increase the axial length of the storage pipe. Therefore, there is a problem that it cannot fit in the conventional place and the layout needs to be changed.

The present invention has been made in view of the above, and an object of the present invention is to provide an exhaust gas purification system capable of improving the exhaust gas purification capacity without changing the layout.

The exhaust gas purification system of the present invention that achieves the above object is an exhaust gas purification system including a purification device for purifying exhaust gas and a storage pipe for accommodating the purification device, and has a first opening at one end. It is provided with a bottomed tubular folding member having a shape and an outlet pipe extending radially outward from the tubular body portion of the folding member, and the folding member is provided from the first opening. With the end portion including the outlet of the storage pipe inserted inside the storage pipe, the outlet faces the bottom portion of the folding member, and is discharged from the outlet between the end portion and the folding member. exhaust gas, after flowing radially outward collides with the bottom portion, the outer periphery of the distal end fold space flowing in the circumferential direction be formed toward the outlet pipe, the folding return space, and the outlet The first space is composed of a columnar first space interposed between the bottom portion and a cylindrical columnar second space interposed between the tubular surface at the end portion and the body portion. The area of the outer cylinder surface, the cross-sectional area of the annulus of the second space, and the opening area of the second opening formed in the body of the folding member and serving as the entrance of the outlet pipe are all described above. It is characterized in that it is set to be larger than the opening area of the outlet .

According to the present invention, in a state where one end of the storage pipe is inserted inside the folding member, a folding space is provided between one end of the storage pipe and the folding portion, and the folding space allows the outlet of the storage pipe. The exhaust gas discharged from the storage pipe can be folded back so as to cover the end portion of the storage pipe. As a result, the total length of the storage pipe can be increased without changing the layout, which is advantageous for increasing the capacity of the purification device stored in the storage pipe, and the exhaust gas purification capacity can be improved. ..

Further, according to the present invention, only one end of the storage pipe is covered with the folding member, and the exhaust gas discharged from the outlet into the folding space flows around the outer periphery of the one end in the circumferential direction, so that only one end thereof is kept warm. can do. As a result, by keeping the entire purification device warm, the upstream side of the purification device becomes too hot and the purification capacity drops, but by keeping only the downstream side of the purification device related to the flow of exhaust gas warm. It is advantageous for improving the purification capacity.

It is a block diagram of the vehicle which illustrates embodiment of the exhaust gas purification system of this invention. It is a development view which illustrates the 1st unit of FIG. It is a perspective view which illustrates the 1st unit of FIG. It is a cross-sectional view which illustrates the 1st unit of FIG. It is a perspective view which illustrates the folding space of FIG. It is a rear view which illustrates the folding member and the outlet pipe of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the figure, x is the traveling direction (front-back direction) of the vehicle 10, y is the side (horizontal direction) of the vehicle 10, and z is the vertical direction (vertical direction).

As illustrated in FIG. 1, the exhaust gas purification system 20 of the embodiment is a system that purifies the exhaust gas G1 discharged from the engine 11 of the vehicle 10, and is installed on one side of the frame 12 that supports the engine 11. Has been done.

In the vehicle 10, a frame 12 composed of a rudder frame supports an engine 11, a power transmission mechanism 13 such as a transmission, a propeller shaft, and a differential, a driven wheel 14, and a passive wheel 15. The exhaust gas G1 generated by the combustion of the fuel of the engine 11 is discharged to the exhaust passage 17 via the exhaust manifold 16, purified by the exhaust gas purification system 20, and then discharged toward the rear of the vehicle 10. There is.

The exhaust gas purification system 20 is composed of a first unit 21 and a second unit 22 arranged on the left and right sides of the frame 12 at an intermediate position in the x direction. The first unit 21 is interposed in the middle position of the exhaust passage 17 and has a purification device. The second unit 22 is a module for supplying urea water.

The first unit 21 is contained in a predetermined layout dimension indicated by a width B1 in the x direction, a length L1 in the y direction, and a height H1 in the z direction. The width B1 is determined by a device (not shown) arranged in front of and behind the first unit 21, the length L1 is determined by the length between the frame 12 and the outermost side of the vehicle 10, and the height H1 is determined by the minimum ground clearance. ing.

The exhaust gas purification system 20 of this embodiment aims to increase the capacity of the purification device in order to improve the purification capacity of the exhaust gas G1. However, if the diameter of the purifying device is increased, the width B1 of the first unit 21 becomes wider and the height H1 becomes higher, which causes the first unit 21 to exceed the predetermined layout dimensions.

Therefore, the exhaust gas purification system 20 includes a folding member 40 and an outlet pipe 41, as well as increasing the axial length of the purification device to increase its capacity with respect to the flow of the exhaust gas G1.

As illustrated in FIGS. 2 and 3, the first unit 21 has an oxidation catalyst 23, a collection filter 24, a urea water injection valve 25, a selective reduction catalyst 26, and an ammonia adsorption catalyst 27 as purification devices. ing. In the first unit 21, the oxidation catalyst 23, the collection filter 24, the urea water injection valve 25, the selective reduction catalyst 26, and the ammonia adsorption catalyst 27 are arranged in order from the upstream side to the downstream side with respect to the flow of the exhaust gas G1. Has been done.

In the exhaust gas purification system 20 of this embodiment, the capacity of the selective reduction catalyst 26 is increased by arranging a plurality of selective reduction catalysts 26 in order with respect to the flow of the exhaust gas G1. If the capacity is the same as that of the plurality of selective reduction catalysts 26, the number of selective reduction catalysts 26 may be one.

The first unit 21 includes a first storage pipe 30 and a second storage pipe 31 for storing the purification device, and a connecting pipe 32 for connecting them. In the first unit 21, the exhaust gas G1 flows from the inlet 33 of the first storage pipe 30 to the outlet 36 of the second storage pipe 31 along a meandering flow path.

The first storage pipe 30 is a storage pipe whose axial direction is oriented in the y direction, and houses the oxidation catalyst 23 and the collection filter 24 inside. The inlet 33 of the first storage pipe 30 is arranged on the frame 12 side, that is, closer to the center of the vehicle 10 in the y direction, and the exit 34 is arranged closer to the outer side of the vehicle 10 in the y direction.

The second storage pipe 31 is a storage pipe whose axial direction is oriented in the y direction, and houses two selective reduction catalysts 26 and an ammonia adsorption catalyst 27 inside. The inlet 35 of the second storage pipe 31 is arranged on the frame 12 side, that is, closer to the center of the vehicle 10 in the y direction, and the exit 36 is arranged closer to the outer side of the vehicle 10 in the y direction.

The connection pipe 32 is a pipe in which the flow path of the exhaust gas G1 flowing inside bends in an S shape, and communicates the outlet 34 of the first storage pipe 30 and the inlet 35 of the second storage pipe 31.

As illustrated in FIG. 4, the first storage pipe 30, the second storage pipe 31, and the connecting pipe 32 are adjacent to each other in the radial direction in the cross section at the intermediate position in the pipe axis direction. By arranging the connecting pipe 32 in the recess formed by the first storage pipe 30 and the second storage pipe 31 adjacent to each other in this way, the first unit 21 becomes compact and has a predetermined layout dimension. It fits in.

As illustrated in FIGS. 2 to 4, the folding member 40 is a bottomed tubular member having one end open, and is connected to a terminal portion 37 including an outlet 36 of the second storage pipe 31. The end 37 of the second storage tube 31 includes an outlet 36 and includes an ammonia adsorption catalyst 27 and at least the end of a selective reduction catalyst 26 located downstream of the second storage tube 31. It is the part that is present. The end portion 37 may be a portion that does not include the entire area of the selective reduction catalyst 26 arranged on the downstream side of the second storage pipe 31.

The folded-back member 40 is composed of a body portion 42, a shoulder portion 43, and a bottom portion 44, and a first opening 45 is formed at one end and a second opening 46 is formed at the body 42, respectively.

The body portion 42 has a tubular shape whose axial direction is oriented in the y direction, and its tubular diameter R1 is longer than the tubular diameter R2 of the second storage pipe 31. The shoulder portion 43 narrows one end of the body portion 42 inward in the radial direction to form the first opening 45. The bottom portion 44 closes the other end of the body portion 42. The opening diameter of the first opening 45 is equal to the pipe diameter R2 and shorter than the cylinder diameter R1. The second opening 46 penetrates the body portion 42 in the radial direction.

With the end 37 of the second storage pipe 31 inserted into the folding member 40 from the first opening 45, the outlet 36 of the second storage pipe 31 faces the bottom 44 of the folding member 40 and is at the bottom. It is separated from 44. Further, the outer circumference of the end portion 37 is separated from the body portion 42 of the folding member 40. As a result, a folding space 47 surrounded by the end portion 37 and the folding member 40 is formed.

As illustrated in FIG. 5, the folding space 47 is composed of a first space 47a and a second space 47b arranged in the order in which the exhaust gas G1 flows. The first space 47a is a columnar, more specifically disk-shaped space, interposed between the outlet 36 and the bottom 44. The second space 47b is an annular columnar space interposed between the tubular surface of the terminal portion 37 and the body portion 42.

The area where the exhaust gas G1 circulates in the first space 47a is the area S2 of the outer cylinder surface of the first space 47a. The area S2 of the outer cylinder surface is set based on the opening area S1 of the outlet 36. Specifically, the area S2 of the outer cylinder surface is the thickness of the first space 47a in the y direction, that is, the separation distance L2 between the outlet 36 and the bottom 44 is the outer peripheral length of the second storage pipe 31 from the opening area S1. By setting it to be equal to or larger than the divided value, the size is set to be equal to or larger than the opening area S1.

The area through which the exhaust gas G1 circulates in the second space 47b is the cross-sectional area S3 of the annulus. The cross-sectional area S3 of this ring is set based on the opening area S1. Specifically, the cross-sectional area S3 of the annulus is the width of the annulus of the second space 47b, that is, the separation distance L3 between the end portion 37 and the body portion 42 is the cross-sectional area S3 of the annulus of the second space 47b. By setting the value to be the opening area S1 or more, the size is set to the opening area S1 or more.

The opening area S4 of the second opening 46 is set based on the opening area S1. Specifically, the opening area S4 is set to a value that is equal to or larger than the opening area S1.

The outlet pipe 41 extends radially outward from the body portion 42 of the folding member 40, and is the first storage pipe in the cross section of the first storage pipe 30 and the second storage pipe 31 at an intermediate position in the pipe axis direction. The connecting pipe 32 is arranged on the side where the connecting pipe 32 is not arranged with respect to the 30 and the second storage pipe 31. Specifically, it is arranged in the recess in which the connecting pipe 32 is not arranged among the recesses formed by the first storage pipe 30 and the second storage pipe 31 adjacent to each other.

The outlet pipe 41 is composed of a reduced diameter portion 48 at one end and a bent portion 49 at the other end. In the reduced diameter portion 48, the diameter of the pipe in the circumferential direction of the body portion 42 is reduced from the body portion 42 toward the outside in the radial direction. The bent portion 49 is bent from the radial direction of the body portion 42 toward the pipe axis direction of the second storage pipe 31.

Next, the flow of the exhaust gas G1 in the exhaust gas purification system 20 will be described. The exhaust gas G1 flows from the inlet 33 of the first storage pipe 30 toward the outlet 34, and passes through the oxidation catalyst 23 and the collection filter 24 in this order. At this time, the hydrocarbon and carbon oxide contained in the exhaust gas G1 are oxidized by the oxidation catalyst 23, and the particulate matter contained in the exhaust gas G1 is collected by the collection filter 24.

Next, the exhaust gas G1 flows in an S shape from the outlet 34 of the first storage pipe 30 toward the inlet 35 of the second storage pipe 31 by the connecting pipe 32, and passes through the urea water injection valve 25. At this time, urea water is sprayed onto the exhaust gas G1 from the urea water injection valve 25.

The exhaust gas G1 then flows from the inlet 35 of the second storage pipe 31 toward the outlet 36 and passes through the two selective reduction catalysts 26 and the ammonia adsorption catalyst 27. At this time, the selective reduction catalyst 26 reduces the nitrogen oxides contained in the exhaust gas G1 using ammonia generated from urea water as a reducing agent, and the ammonia adsorption catalyst 27 adsorbs ammonia.

Next, the exhaust gas G1 flows from the outlet 36 of the second storage pipe 31 to the folding member 40 and the outlet pipe 41 in this order from the outlet 36 to the outlet pipe 41 via the folding space 47.

Specifically, as illustrated in FIG. 6, the exhaust gas G1 discharged from the outlet 36 collides with the bottom portion 44 of the folding member 40 in the first space 47a and flows outward in the radial direction. Next, the exhaust gas G1 flows around the outer periphery of the end portion 37 in the second space 47b in the circumferential direction, and flows from the second opening 46 to the outlet pipe 41.

In this way, with the end portion 37 of the second storage pipe 31 inserted inside the folding member 40, the folding space 47 is provided between the end portion 37 and the folding member 40, whereby the folding space 47 The exhaust gas G1 discharged from the outlet 36 of the second storage pipe 31 can be folded back so as to cover the end portion 37 of the second storage pipe 31. As a result, the total length of the second storage pipe 31 in the y direction can be increased without changing the layout. Along with this, it becomes advantageous to increase the capacity of the selective reduction catalyst 26 housed in the second storage pipe 31, and the nitrogen oxide purification capacity of the exhaust gas G1 can be improved.

Further, since the folding member 40 covers only the end portion 37 of the second storage pipe 31, the exhaust gas G1 discharged from the outlet 36 into the folding space 47 flows around the end portion 37, and thus the end portion thereof. Only 37 can be kept warm. As a result, by keeping warm only on the downstream side where the temperature is lower than that on the upstream side of the second storage pipe 31, it is possible to keep the downstream side moderately warm while avoiding excessive heat retention on the upstream side. It is advantageous for improving the purification capacity of nitrogen.

In particular, in the selective reduction catalyst 26, the temperature decreases from the upstream side to the downstream side with respect to the flow of the exhaust gas G1. Further, in the selective reduction catalyst 26, there is a temperature range in which ammonia can be used as a reducing agent to efficiently reduce nitrogen oxides, and the purification rate decreases when the temperature is higher than the temperature range. Therefore, as described above, by covering only the end portion 37 of the second storage pipe 31 with the folding member 40, the downstream side of the selective reduction catalyst 26, which is likely to be lower than the temperature zone, is kept warm. It is advantageous for improving the purification capacity of nitrogen oxides.

In this embodiment, the area S2 of the outer cylinder surface of the first space 47a, the cross-sectional area S3 of the annulus of the second space 47b, and the opening area S4 of the second opening 46 are each set to the opening area S1 of the outlet 36. It is set based on. Therefore, the folded portion in the flow path of the exhaust gas G1 can be made compact without reducing the passing area of the exhaust gas G1. As a result, an increase in exhaust resistance can be avoided even if the second storage pipe 31 is folded back so as to cover the end portion 37.

Further, since the reduced diameter portion 48 of the outlet pipe 41 is reduced in diameter from the body portion 42 toward the outer side in the radial direction, the exhaust gas G1 can be discharged from the outlet pipe 41 more smoothly. In this embodiment, since the body portion 42 has a tubular shape, the diameter of the reduced diameter portion 48 is reduced only in the circumferential direction of the body portion 42 toward the radial outer side of the body portion 42. This is advantageous for smoothly guiding the exhaust gas G1 flowing in the circumferential direction around the outer periphery of the end portion 37 to the bent portion 49 by the second space 47b.

In addition, the connection pipe 32 is arranged with respect to the first storage pipe 30 and the second storage pipe 31 in the cross section of the outlet pipe 41 at the intermediate position in the pipe axis direction of the first storage pipe 30 and the second storage pipe 31. Since it is arranged on the side that is not provided, the first unit 21 can be made compact.

In this embodiment, a configuration including an oxidation catalyst 23, a collection filter 24, a urea water injection valve 25, a selective reduction catalyst 26, and an ammonia adsorption catalyst 27 has been described as an example of the purification device, but the present invention is not limited thereto. .. For example, a NOx storage reduction catalyst was used instead of the combination of the oxidation catalyst 23, the urea water injection valve 25, and the selective reduction catalyst 26, or the urea water injection valve 25, the selective reduction catalyst 26, and the ammonia adsorption catalyst 27. Can be illustrated. Further, an ammonia oxidation catalyst may be used instead of the ammonia adsorption catalyst 27.

The first storage pipe 30 and the second storage pipe 31 are not limited to a configuration in which the respective pipe axial directions are oriented in the y direction. For example, the first storage pipe 30 and the second storage pipe 31 may be arranged so that their respective building axis directions face the x direction.

The folding member 40 can also be connected to the end portion of the first storage pipe 30. That is, the folding member 40 may be connected to the end of the first storage pipe 30, and the connecting pipe 32 may be connected to the outlet pipe 41. By connecting the folding member 40 to the end of the first storage pipe 30 in this way, it is possible to increase the capacities of the oxidation catalyst 23 and the collection filter 24.

20 Exhaust gas purification system 26 Selective reduction catalyst (purification device)
27 Ammonia adsorption catalyst (purification device)
32 Second storage pipe 36 Outlet 37 End part 40 Folding member 41 Exit pipe 42 Body 44 Bottom 47 Folding space

Claims (2)

In an exhaust gas purification system provided with a purification device for purifying exhaust gas and a storage pipe for accommodating the purification device.
It is provided with a bottomed tubular folding member having a first opening at one end, and an outlet pipe extending radially outward from the tubular body of the folding member.
In a state where the end portion including the outlet of the storage pipe is inserted into the inside of the folding member from the first opening, the outlet faces the bottom of the folding member.
After the exhaust gas discharged from the outlet between the end portion and the folding member collides with the bottom portion and flows outward in the radial direction, the outer periphery of the end portion is circumferentially oriented toward the outlet pipe. A flowing folding space is formed ,
The folded space is composed of a columnar first space interposed between the outlet and the bottom portion and a cylindrical columnar second space interposed between the tubular surface of the end portion and the body portion. Has been
The area of the outer cylinder surface of the first space, the cross-sectional area of the annulus of the second space, and the opening area of the second opening formed on the body of the folding member and serving as the entrance of the outlet pipe. An exhaust gas purification system characterized in that each of the above is set to be equal to or larger than the opening area of the outlet . The exhaust gas purification system according to claim 1 , wherein the outlet pipe has a diameter-reduced portion whose diameter is reduced outward in the radial direction from the body portion.