Exhaust Gas Stirring Device

An exhaust gas stifling device is to be mounted in a tubular body that forms a flow path for exhaust gas. The device comprises a main body that comprises a plurality of base plates facing one another at specified distances and a plurality of blade portions that are provided on a downstream side of a flow direction of the exhaust gas and are inclined with respect to the flow direction of the exhaust gas. The plurality of blade portions are formed so that there is a route in which vectors X of the individual blade portions, each vector X being defined below, go around in a given direction when viewed from a downstream side of a flow direction D. Vector X: a component of a vector in a direction of the blade portion guiding the exhaust gas, in a plane perpendicular to the flow direction of the exhaust gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This international application claims the benefit of Japanese Patent Application No. 2012-185188 filed Aug. 24, 2012 in the Japan Patent Office, and the entire disclosure of Japanese Patent Application No. 2012-185188 is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an exhaust gas stirring device to be provided in a flow path for exhaust gas from an internal combustion engine such as a diesel engine to stir the exhaust gas.

BACKGROUND ART

A technique is conventionally known in which a reducing agent composed of a liquid such as urea water is injected into exhaust gas from a diesel engine to reduce nitrogen oxides in the exhaust gas to nitrogen. The above-described reducing agent needs to be diffused uniformly in the exhaust gas. A weak atmosphere of the reducing agent caused by insufficient diffusion leads to discharge of the nitrogen oxides without sufficient reduction occurring, whereas an excessively strong atmosphere of the reducing agent caused by insufficient diffusion results in an excess reducing agent adhered to a catalyst provided on a downstream side of a flow path for the exhaust gas, to thereby decrease the performance of the catalyst.

A technique has thus been suggested, as shown in Patent Document 1, in which a first and a second plate member each provided with blade portions and a slit are combined in a cross-shaped form by engaging their slits with each other, and the first and the second plate member are arranged in an exhaust pipe along its axial direction, to thereby generate a turning flow in the exhaust gas by means of the blade portions.

A technique has also been suggested, as shown in Patent Document 2, in which triangular fin portions are formed in a plate disc by cutting and raising the portions by pressing, etc., and the disc is arranged at right angles to the flow direction of the exhaust gas, to thereby generate a turning flow in the exhaust gas by means of the fin portions.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 2: Japanese Unexamined Patent Application Publication No. 2010-144569

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The techniques disclosed in Patent Documents 1 and 2, however, require a device with a complicated structure to generate a turning flow. The present invention has been made in view of the above, and it is an aspect of the present invention to provide an exhaust gas stirring device that can solve the above-described problem.

Means for Solving the Problems

An exhaust gas stirring device according to an aspect of the present invention is an exhaust gas stirring device to be mounted in a tubular body that forms a flow path for exhaust gas and comprises a main body and a plurality of blade portions. The main body comprises a plurality of base plates that face one another at specified distances. The plurality of blade portions are provided to the base plates on a downstream side of a flow direction of the exhaust gas and are inclined with respect to the flow direction of the exhaust gas.

The plurality of blade portions are formed so that there is a route in which vectors X of the individual blade portions, each vector X being defined below, go around in a given direction when viewed from the downstream side of the flow direction of the exhaust gas.

Vector X: a component of a vector in a direction of the blade portion guiding the exhaust gas, in a plane perpendicular to the flow direction of the exhaust gas.

In the exhaust gas stirring device according to the aspect of the present invention, the plurality of blade portions are formed to meet the above-described condition regarding vector X so that a turning flow is generated in the exhaust gas. This further improves the effect of the exhaust gas stirring device stirring the exhaust gas.

In the exhaust gas stirring device, a plurality of blade portions guiding the exhaust gas in different directions can be provided to the plurality of base plates facing one another at specified distances. It is thus not always necessary to provide differently oriented base plates corresponding to the respective blade portions guiding the exhaust gas in different directions. This leads to simplification of the configuration of the exhaust gas stirring device.

The main body may be formed, for example, from at least one sheet of bent plate member, and the plurality of base plates may each be a part of the bent plate member. In this case, the production of the main body and the mounting thereof to the tubular body are easy.

The main body may, for example, have an extended portion that extends outward from other portions of the main body on an upstream side of the flow direction of the exhaust gas. In this case, the exhaust gas stirring device can be welded to an inner surface of the tubular body at the extended portion. This enables much easier mounting of the exhaust gas stirring device.

EXPLANATION OF REFERENCE NUMERALS

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described based on the drawings.

First Embodiment

1. Configuration of Exhaust Gas Stirring Device1

A configuration of an exhaust gas stirring device1will be described based onFIG. 1toFIG. 13. The exhaust gas stirring device1is a device to be mounted in a tubular body101that forms a flow path for exhaust gas from a diesel engine. The flow path for the exhaust gas is provided, on its upstream side from the exhaust gas stirring device1, with a mechanism (not shown) in which a reducing agent composed of a liquid such as urea water is injected into the exhaust gas and is provided, on its downstream side from the exhaust gas stirring device1, with a catalyst (not shown) that provides action to reduce nitrogen oxides.

The exhaust gas stirring device1is formed by bending a sheet of metal plate member having a form as shown inFIG. 3into a form as shown inFIG. 1. To be more specific, the exhaust gas stirring device1comprises a main body3and a plurality of blade portions5-20. The main body3is divided with bend lines (indicated as dotted lines inFIG. 3) into sections21-31. When the main body3is bent along each bend line, the sections21-31are brought into a positional relation as shown inFIG. 4. At this time, the sections22,24,26,28, and30are all planes facing one another at specified distances in parallel with one another. The sections22,24,26,28, and30show an embodiment of a plurality of base plates. The sections21,23,25,27,29, and31face an inner surface of the tubular body101when the exhaust gas stirring device1is mounted in the tubular body101.

In the sections21,23,25,27,29, and31of the main body3, portions on a lower side ofFIG. 3(portions on an upstream side of a flow direction D of the exhaust gas) are formed to be extended portions33that extend outward from other portions of the main body3by being bent into a stepped form as shown inFIG. 1. When the exhaust gas stirring device1is mounted in the tubular body101, only the extended portions33contact the inner surface of the tubular body101to provide a gap between the other portions of the exhaust gas stirring device1and the inner surface of the tubular body101. By welding the extended portions33and the inner surface of the tube body101together, the exhaust gas stirring device1can be fixed to the tubular body101.

A plurality of blade portions5-20are provided to the main body3on an upper side ofFIG. 3(a downstream side of the flow direction D of the exhaust gas). The plurality of blade portions5-20are each inclined with respect to the flow direction D of the exhaust gas by being bent along bend lines (shown as dotted lines inFIG. 3) near the main body3.

The bend lines for the blade portions8,9,12,13,16, and17from among the plurality of blade portions5-20are perpendicular to the flow direction D of the exhaust gas, and the bend lines for the blade portions5,6,7,10,11,14,15,18,19, and20are oblique to the flow direction D of the exhaust gas. Thus, the directions into which the blade portions8,9,12,13,16, and17fall by being bent along their respective bend lines and the directions into which the blade portions5,6,7,10,11,14,15,18,19, and20fall by being bent along their respective bend lines are different from one another.

FIGS. 5A-5Cshow forms of the blade portion5. The forms of the blade portion5may also be any of those shown inFIGS. 6A-6C,7A-7C,8A-8C,9A-9C,10A-10C, and11A-11C. The blade portions6,7,10,11,14,15,18,19, and20can have similar forms to the forms of the blade portion5.

Being inclined with respect to the flow direction D of the exhaust gas as described above, the plurality of blade portions5-20guide the exhaust gas flowing from the upstream side along the flow direction D of the exhaust gas into directions that correspond to the respective inclination of the individual blade portions. The direction in which each blade portion is inclined and the direction in which each blade portion guides the exhaust gas are set as described below.

A vector in a direction of each blade portion guiding the exhaust gas is defined as vector E. Vector E can be a vector directing from a bottom direction of each blade portion along a surface of each blade portion towards an end direction of each blade portion. For example, vector E of the blade portion8,9,12,13,16,17is as shown inFIG. 12A. Vector E of the blade portion5,6,7,10,11,14,15,18,19,20is as shown inFIG. 12B. A component of vector E in a plane perpendicular to the flow direction D of the exhaust gas is defined as vector X. Vector X is uniformly determined for each blade portion.

Vectors X of the individual blade portions, as a whole, go around in a given route as shown inFIG. 13when the exhaust gas stirring device1is viewed from the downstream side of the flow direction D of the exhaust gas. In other words, when the exhaust gas stirring device1is viewed from the downstream side of the flow direction D of the exhaust gas, there is a route in which a step of moving from an arbitrary blade portion to its adjacent blade portion having an amount of change in the direction of vector X of 90 degrees or below is sequentially repeated to thereby enable a return to the original blade portion. InFIG. 13, the arrows indicate the directions of the vectors X.

2. Effects Provided by Exhaust Gas Stirring Device1

(1) When the exhaust gas stirring device1is viewed from the downstream side of the flow direction D of the exhaust gas, the vectors X of the individual blade portions are arranged in a counterclockwise direction as shown inFIG. 13. Thus, the exhaust gas passing through the exhaust gas stirring device1is guided in the direction of the vector X at each blade portion to result in generation of a turning flow in the exhaust gas passing through the exhaust gas stirring device1as a whole in a counterclockwise direction as shown inFIG. 13. This further improves the effect of the exhaust gas stirring device1stirring the exhaust gas.
(2) In the exhaust gas stirring device1, both the blade portions8,9,12,13,16, and17having vectors X in up-and-down directions inFIG. 13and the blade portions5,6,10,11,14,15,19, and20having vectors X in left-and-right directions inFIG. 13can be provided to the sections22,24,26,28, and30of the main body3that are parallel to one another. Thus, it is not necessary to provide differently oriented base plates corresponding to the respective directions of the vectors X in the tubular body101.
(3) Since the exhaust gas stirring device1is formed by bending a sheet of metal plate member, its production and mounting to the tubular body101are easy.
(4) The exhaust gas stirring device1can be welded, at the extended portions33that extend outward, to the inner surface of the tubular body101. This further facilitates the mounting of the exhaust gas stirring device1.
(5) The exhaust gas stirring device1has the sections22,24,26,28, and30that are arranged parallel to one another and the blade portions5,6,8-17,19, and20that are provided between these sections, and thus, the blade portions5,6,8-17,19, and20can cover a wide range of a cross section perpendicular to an axial direction of the tubular body101. This enables the exhaust gas stirring device1to generate a turning flow efficiently.
(6) The exhaust gas stirring device1has the sections22,24,26,28, and30that are arranged parallel to one another and the blade portions5,6,8-17,19, and20that are provided between these sections, and thus, the blade portions5,6,8-17,19, and20are hard to interfere with one another. This enables easy production of the exhaust gas stirring device1.

Second Embodiment

1. Configuration of Exhaust Gas Stirring Device1

A configuration of the exhaust gas stirring device1will be described based onFIG. 14toFIG. 18. The exhaust gas stirring device1is a device to be mounted in the tubular body101that forms a flow path for exhaust gas. The exhaust gas stirring device1is a combination of two members50that are each formed by bending a sheet of metal plate member having a form as shown inFIG. 16into a form as shown inFIG. 14.

The member50comprises a main body51and a plurality of blade portions52-59. The main body51is divided with bend lines (indicated as dotted lines inFIG. 16) into sections60-65. When the main body51is bent along each bend line, the sections60-65are brought into a positional relation as shown inFIG. 18. At this time, the sections61,63, and65are all planes facing one another at specified distances in parallel with one another. The sections61,63, and65show an embodiment of a plurality of base plates. The sections60,62, and64face the inner surface of the tubular body101when the exhaust gas stirring device1is mounted in the tubular body101. The two members50are combined together oriented as shown inFIG. 17andFIG. 18.

In the sections60,62, and65of the main body51, portions on a lower side ofFIG. 16(portions on the upstream side of the flow direction D of the exhaust gas) are formed to be extended portions67that extend outward from other portions of the main body51by being bent into a stepped form as shown inFIG. 14. When the exhaust gas stirring device1is mounted in the tubular body101, only the extended portions67contact the inner surface of the tubular body101to provide a gap between the other portions of the exhaust gas stirring device1and the inner surface of the tubular body101. By welding the extended portions67and the inner surface of the tubular body101together, the exhaust gas stirring device1can be fixed to the tubular body101.

A plurality of blade portions52-59are provided to the main body3on an upper side ofFIG. 16(the downstream side of the flow direction D of the exhaust gas). The plurality of blade portions52-59are each inclined with respect to the flow direction D of the exhaust gas by being bent along bend lines (shown as dotted lines inFIG. 16) near the main body51.

The blade portions52,53,56, and58are bent similarly as are the blade portion5, etc. of the first embodiment. The blade portions54,55,57, and59are bent similarly as are the blade portion8, etc. of the first embodiment.

Being inclined with respect to the flow direction D of the exhaust gas as described above, the plurality of blade portions52-59guide the exhaust gas flowing from the upstream side along the flow direction D of the exhaust gas into directions that correspond to the respective inclination of the individual blade portions. The direction in which each blade portion is inclined and the direction in which each blade portion guides the exhaust gas are set as described below.

Vectors X of the individual blade portions, as a whole, go around in a given route as shown inFIG. 19when the exhaust gas stirring device1is viewed from the downstream side of the flow direction D of the exhaust gas. In other words, when the exhaust gas stirring device1is viewed from the downstream side of the flow direction D of the exhaust gas, there is a route in which a step of moving from an arbitrary blade portion to its adjacent blade portion having an amount of change in the direction of vector X of 90 degrees or below is sequentially repeated to thereby enable a return to the original blade portion. InFIG. 19, arrows indicate the directions of the vectors X.

2. Effects Provided by Exhaust Gas Stirring Device1

(1) When the exhaust gas stirring device1is viewed from the downstream side of the flow direction D of the exhaust gas, the vectors X of the individual blade portions are arranged in a counterclockwise direction, as shown inFIG. 19. Thus, the exhaust gas passing through the exhaust gas stirring device1is guided in the direction of the vector X at each blade portion to result in generation of a turning flow in the exhaust gas passing through the exhaust gas stirring device1as a whole in a counterclockwise direction as shown inFIG. 19. This further improves the effect of the exhaust gas stirring device1stirring the exhaust gas.
(2) In the exhaust gas stirring device1, both the blade portion54,55, and57having vectors X in up-and-down directions inFIG. 19and the blade portion52,53, and58having vectors X in left-and-right directions inFIG. 19can be provided to the sections61and63of the main body3that are parallel to each other. Thus, it is not necessary to provide differently oriented base plates corresponding to the respective directions of the vectors X in the tubular body101.
(3) Since the two members50constituting the exhaust gas stirring device1are each formed by bending a sheet of metal plate member, their production and mounting to the tubular body101are easy.
(4) The exhaust gas stirring device1can be welded, at the extended portions67that extend outward, to the inner surface of the tubular body101. This further facilitates the mounting of the exhaust gas stirring device1.

The present invention should not be restricted to the above-described embodiments. Needless to say, it can be practiced in various forms within the scope of the present invention.

The main body3,51, for example, may be formed by joining a plurality of components. The sections22,24,26,28, and30of the main body3, for example, may be produced separately from other portions of the main body3and joined together with the other portions later.

The exhaust gas stirring device1may be formed by joining the blade portions5-20and52-59produced separately from the main body3,51to the main body3,51.

Furthermore, the main body3,51may not comprise the extended portions33,67. In this case, a part or the whole of an outer surface of the main body3,51, for example, can be joined to the inner surface of the tubular body101.

The forms of the blade portions5-20and52-59, the directions of the inclination thereof, and the like should not be restricted to those described in the above embodiments but can be set as appropriate.

Although the vector X of each blade portion changes in direction with respect to its adjacent blade portion in units of 90 degrees in the above-described embodiments, it may change in direction in units of different degrees (such as 30 degrees, 45 degrees, 60 degrees, and so on).