JP2009114872A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device with PM collection efficiency improved by shortening moving distance of PM in ion wind and exhaust gas toward a dust collection filter device from a needle shaped electric discharge electrode electric discharge part composing an electric discharge electrode. <P>SOLUTION: The exhaust emission control device 50 is provided with the dust collection filter device 2 comprising a dust collection filter device 2 and a dust collection electrode arranged along an outer shell 1, an exhaust gas passage 7 formed inside of the dust collection filter device 2 and having exhaust gas containing PM flow therein, and an electric discharge electrode 40 installed in a direction crossing an exhaust gas passage 7 under a condition where mutual tips are separated and generating the ion wind 30 inducing and forming secondary flow in a direction perpendicular to the exhaust gas flow in a gap with the dust collection filter device 2 when voltage is applied. An exhaust gas swirl forming pipe 10 opening in a tangential direction to the exhaust gas passage 7 is provided on the outer shell 1 positioned at an upstream side of the electric discharge electrode 40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification apparatus that removes particulate matter (particulate matter, hereinafter referred to as PM) contained in exhaust gas of a diesel engine, a gasoline engine, or the like.

FIG. 5 is a schematic cross-sectional view showing an example of an electric dust collector disclosed in Patent Document 1 (WO2005 / 021161).
In FIG. 5, a dust collecting device 100 includes a cylindrical outer shell 1, a discharge electrode 40 comprising a discharge electrode main portion 4 and a discharge electrode discharge portion 3, a dust collection filter device comprising a dust collection electrode and a dust collection filter layer. 2 are provided. The discharge electrode 40 is connected to the high voltage generator 20 through the high-voltage conductor 5a and the insulator 5. The insulator 5 is accommodated in the insulator chamber 6.

  The outer shell 1 is formed in a cylindrical shape, and the inside thereof is an exhaust gas passage 7 through which exhaust gas containing PM flows, and the exhaust gas passes through the exhaust gas passage 7 along the discharge electrode 40 as indicated by arrows in FIG. It comes to flow. For this reason, the discharge electrode 40 includes a discharge electrode main portion 4 extending in the direction of the exhaust gas flow in the center of the exhaust gas passage 7, and the dust collection filter device 2 across the exhaust gas passage 7 from the discharge electrode main portion 4. It is comprised from the several discharge electrode discharge part 3 formed in the stab shape extended toward the side.

  In such a dust collector 100, when a high voltage from the high voltage generator 20 is applied to the discharge electrode 40 via the high-voltage conductor 5a, dust is collected from the discharge electrode main portion 4 and the plurality of discharge electrode discharge portions 3. An ion wind induced by the ions jumping toward the dust collection electrode of the filter device 2 is generated. As a result, most of the PM contained in the exhaust gas flow passes through the dust collection electrode, and the PM is guided together with the gas to the dust collection filter layer disposed outside the dust collection electrode. Most of it is collected and becomes purified gas.

WO2005 / 021161

In general, a diesel particulate filter (hereinafter referred to as DPF), which is a graphite removing device, is used to remove PM in exhaust gas from a diesel engine or the like and perform purification treatment. However, such DPF has the following problems.
In other words, over time, in the DPF, pressure loss increases due to clogging of the filter, which causes a load on the exhaust side, fuel consumption efficiency increases, and engine output decreases. become. Moreover, if the filter is further clogged, there is a possibility that the engine will stop.

Therefore, as a prior art, an electric dust collector capable of processing PM with a low pressure loss, such as Patent Document 1, is employed. However, this electric dust collector has the following problems to be solved.
(1) The exhaust gas introduced into the exhaust gas passage 7 is a rectified and uniform flow, and the PM easily adheres to the tip of the stab-like discharge electrode discharge part 3 constituting the discharge electrode 40. As a result, the discharge current is suppressed, and the collection efficiency of the electric dust collector 100 is lowered.
(2) Since the surface of the insulator 5 becomes dirty with the remaining PM over time, insulation cannot be maintained and a predetermined voltage cannot be applied.
(3) Compared with DPF, the collection efficiency is low and the collection efficiency needs to be improved.
(4) The PM in the exhaust gas is moved in a direction orthogonal to the exhaust gas flow by the ion wind and collected in the dust collection filter layer outside the dust collection electrode, but the distance the PM moves toward the center position of the electrode cross section The longer the mainstream axial velocity vector, the lower the PM collection performance near the center.

  The present invention has been made in view of such a situation, and an object of the present invention is to move the ion wind and the PM in the exhaust gas from the stab-like discharge electrode discharge portion constituting the discharge electrode toward the dust collecting filter device side. An object of the present invention is to provide an exhaust gas purifying apparatus that improves the PM collection efficiency by shortening the distance.

  In order to solve the above-described problems of the prior art, the present invention includes a cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer. An exhaust gas passage formed inside the dust collecting filter device through which exhaust gas containing particulate matter flows and a tip of the exhaust gas passage in the direction crossing the exhaust gas passage are separated from each other and a voltage is applied. An exhaust gas purification apparatus comprising a discharge electrode that generates an ionic wind that induces and forms a secondary flow in a direction orthogonal to the exhaust gas flow between the dust collection filter device and a position on the upstream side of the discharge electrode. The outer shell is provided with an exhaust gas swirl flow pipe that opens in a tangential direction with respect to the exhaust gas passage.

  In the present invention, it is preferable that the swirl flow forming pipe is provided so that an opening end to the exhaust gas passage is opposed to a center of the exhaust gas passage.

  The present invention also includes a cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device. An exhaust gas passage through which exhaust gas containing particulate matter flows, and the dust collection filter device when a voltage is applied between the exhaust gas passage and the exhaust gas passage installed in a direction across the exhaust gas passage. In the exhaust gas purification apparatus, the discharge electrode for generating an ionic wind that induces and forms a secondary flow in a direction orthogonal to the exhaust gas flow is disposed upstream of the discharge electrode in the exhaust gas passage. A guide member is provided for deflecting the exhaust gas flow toward the dust collecting filter device after the collision.

  Furthermore, the present invention includes a cylindrical outer shell, a dust collecting filter device disposed along the outer shell and including a dust collecting electrode and a dust collecting filter layer, and formed inside the dust collecting filter device. An exhaust gas passage through which exhaust gas containing particulate matter flows, and the dust collection filter device when a voltage is applied between the exhaust gas passage and the exhaust gas passage installed in a direction across the exhaust gas passage. In the exhaust gas purification apparatus, the discharge electrode for generating an ionic wind that induces and forms a secondary flow in a direction orthogonal to the exhaust gas flow is disposed upstream of the discharge electrode in the exhaust gas passage. A swirl fin is provided for applying a swivel force in the radial direction.

  As described above, the exhaust gas purifying apparatus according to the present invention includes a cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and the dust collecting device. An exhaust gas passage that is formed inside the filter device and through which exhaust gas containing particulate matter flows, and is installed in the exhaust gas passage in a state of being separated from each other in a direction across the exhaust gas passage, and when a voltage is applied, A discharge electrode for generating an ion wind that induces and forms a secondary flow in a direction perpendicular to the exhaust gas flow between the dust collection filter device and the outer electrode located upstream of the discharge electrode. The shell is provided with a swirl flow forming pipe that opens in a tangential direction with respect to the exhaust gas passage, or the swirl flow forming pipe so that the opening end to the exhaust gas passage faces the center of the exhaust gas passage. Is provided Therefore, a tangential swirling flow is formed in the exhaust gas passage due to the presence of the swirling flow forming tube, and the swirling flow winds up the exhaust gas flow in the central portion of the exhaust gas passage to the periphery, and the tip of the sting-shaped discharge electrode discharge part PM is prevented from adhering to the part, the distance of the PM in the exhaust gas passage to the dust collecting filter device side is shortened, and the amount of PM collected in the dust collecting filter device in the exhaust gas passage is increased. Become.

  The increase in the amount collected by such a dust collection filter device improves the collection efficiency of the dust collection filter device and reduces the remaining PM flowing downstream in the direction of the exhaust gas passage. The part is prevented from being soiled and insulator insulation is maintained, and a predetermined voltage can be constantly applied stably.

  Further, the present invention provides the above-described exhaust gas purifying apparatus, wherein the guide member deflects the exhaust gas flow toward the dust collecting filter device after colliding the exhaust gas flow on the upstream side of the discharge electrode in the exhaust gas passage. Therefore, the exhaust gas flow in the exhaust gas passage is deflected in the radial direction by colliding with the guide member, and the distance that PM in the exhaust gas flow reaches the dust collecting filter device can be shortened. As a result, the amount of PM collected in the dust collection filter device in the exhaust gas passage is increased, and the collection efficiency of the dust collection filter device can be improved.

  Furthermore, in the exhaust gas purification apparatus according to the present invention, since a swirl fin is provided on the upstream side of the discharge electrode in the exhaust gas passage to give a swirl force in the radial direction to the exhaust gas flow. Due to the presence of the swirling fins, the exhaust gas flow and PM are given a moving component in the circumferential direction while being moved in the radial direction, and the same effect as in the above invention can be obtained.

  Hereinafter, an exhaust gas purifying apparatus according to the present invention will be described in detail based on embodiments thereof with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view showing an exhaust gas purifying apparatus according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG.
1 and 2, an exhaust gas purifying apparatus 50 according to this embodiment includes a cylindrical outer shell 1, a discharge electrode 40 including a discharge electrode main portion 4 and a discharge electrode discharge portion 3, a dust collection electrode, and a dust collection filter. And a dust collecting filter device 2 composed of layers. And the discharge electrode 40 is connected to the high voltage generator via the high voltage lead and insulator which are not illustrated (refer FIG. 5). The dust collecting electrode is made of a conductive material such as a conductive wire mesh having an opening through which PM passes, and the dust collecting filter layer is made of a breathable material such as a laminated wire mesh or porous ceramics. Has been.

The outer shell 1 is formed in a cylindrical shape that is disposed sideways, and the opening end on the upstream side (left side in FIG. 1) is closed. Inside the outer shell 1 is an exhaust gas passage 7 through which exhaust gas containing PM flows. A discharge electrode 40 is disposed in the center of the exhaust gas passage 7. The discharge electrode 40 is located at the center of the exhaust gas passage 7 and extends along the axial direction of the exhaust gas passage 7, and the dust collecting filter crosses the exhaust gas passage 7 from the discharge electrode main portion 4. It is comprised from the several discharge electrode discharge part 3 formed in the stab shape extended toward the apparatus 2 side.
These discharge electrode discharge portions 3 are provided at regular intervals along the axial direction of the discharge electrode main portion 4 from the upstream side to the downstream side, and at the same position in the axial direction of the discharge electrode main portion 4. In a state where the tips are separated from each other, the outer peripheral surface of the discharge electrode main portion 4 is radially arranged with a certain interval (for example, in the case of four, an interval of 90 degrees).

  In such an exhaust gas purifying device 50, a high voltage from a high voltage generator (not shown) is applied to the discharge electrode 40 via a high-voltage conductor (see FIG. 5), so that the discharge electrode main portion 4 and a plurality of discharge electrodes are provided. Ions jump out from the electrode discharge part 3 toward the dust collection electrode of the dust collection filter device 2 located inside the outer shell 1, and an ion wind 30 induced by the ions is generated. Due to the ion wind 30, most of the PM contained in the exhaust gas flow passes through the dust collecting electrode and is led together with the gas to the dust collecting filter layer disposed outside the dust collecting electrode. Most of the water is collected and led to the downstream side as purified gas.

Further, in the exhaust gas purifying device 50 according to the first embodiment of the present invention, the outer shell 1 positioned on the upstream side of the discharge electrode 40 is tangential to the exhaust gas passage 7 as shown in FIGS. One swirling flow forming tube 10 is integrally provided. That is, as shown in FIG. 2, the swirling flow forming tube 10 is formed on one side of the upper outer peripheral surface of the outer shell 1 when viewed from the front, and extends along the vertical direction. The exhaust gas introduced into the outer shell 1 from the forming tube 10 is configured to be a swirling flow 11 in the exhaust gas passage 7.
It should be noted that the outer shell 1 positioned on the upstream side of the discharge electrode 40 has an open end to the exhaust gas passage 7 facing each other with respect to the center of the exhaust gas passage 7 as shown by a chain line in FIGS. Two swirl flow forming tubes 10, 10a may be provided. The lower swirl flow forming tube 10a is the same as the upper swirl flow forming tube 10 except that the lower swirl flow forming tube 10a is disposed on the lower side opposite to the upper swirl flow forming tube 10 and is displaced in the axial direction. It is arranged and shaped.

In the exhaust gas purifying apparatus 50 of the first embodiment as described above, the outer shell 1 has one swirl flow forming pipe 10 that opens in a tangential direction with respect to the exhaust gas passage 7 or an open end to the exhaust gas passage 7. In addition to the swirl flow forming tube 10, a swirl flow forming tube 10 a is further provided to face each other with respect to the center of the exhaust gas passage 7, and the swirl flow forming tubes 10, 10 a are arranged on the upstream side of the discharge electrode 40. Has been.
Accordingly, the exhaust gas introduced from the swirl flow forming pipes 10 and 10a becomes a tangential swirl flow 11 in the exhaust gas passage 7, and the exhaust gas flow at the center of the exhaust gas passage 7 is rolled up by the swirl flow 11 thus formed. Thus, PM is prevented from adhering to the tip of the stab-like discharge electrode discharge part 3, and the distance that the PM in the exhaust gas passage 7 reaches the dust collection filter device 40 side is shortened. The amount of PM collected by 2 increases, and a purified gas with little residual PM can be obtained on the downstream side of the purification device 50.

  Further, since the amount of collected PM in the dust collection filter device 2 increases, the collection efficiency of the dust collection filter device 2 is improved, and the remaining PM flowing in the direction of the exhaust gas passage 7 is reduced. It becomes possible to prevent the insulator (see FIG. 5) from being contaminated by PM, the insulation of the insulator is maintained, and a predetermined voltage can be constantly applied stably.

[Second Embodiment]
FIG. 3A is a schematic cross-sectional view showing an exhaust gas purifying apparatus according to a second embodiment of the present invention, and FIG. 3B is an enlarged view of a Z portion in FIG.
The exhaust gas purifying device 50 according to the second embodiment deflects the exhaust gas flow toward the dust collection filter device 2 after colliding the exhaust gas flow with the central axis C upstream of the discharge electrode 40 in the exhaust gas passage 7. A cone-shaped guide member 21 is provided. The cone-shaped guide member 21 is formed by bending a plate-like body, and the front surface 21a facing the upstream side where the exhaust gas flows is inclined obliquely rearward from the center portion toward the downstream side. It is a slanted surface of “shape”.
Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

Thus, in the exhaust gas purification device 50 according to the second embodiment of the present invention, the cone-shaped guide member 21 that deflects the exhaust gas flow toward the dust collection filter device side 2 is disposed upstream of the discharge electrode 40 in the exhaust gas passage 7. Since it is provided, the exhaust gas flow near the central axis C flowing in the exhaust gas passage 7 collides with the cone-shaped guide member 21 and is deflected radially outward by the upstream front surface 21a to be collected by the dust collecting filter device. The distance to which the PM in the exhaust gas flow reaches the dust collecting filter device 2 is shortened.
As a result, the amount of PM collected in the dust collection filter device 2 in the exhaust gas flowing through the exhaust gas passage 7 is increased, the PM collection efficiency of the dust collection filter device 2 is improved, and the purified gas with less residual PM. Can be obtained.

[Third Embodiment]
FIG. 4A is a schematic cross-sectional view showing an exhaust gas purifying apparatus according to a third embodiment of the present invention, FIG. 4B is an enlarged view of a Y portion in FIG. It is.
The exhaust gas purifying device 50 according to the third embodiment deflects the exhaust gas flow toward the dust collection filter device 2 after colliding the exhaust gas flow with the central axis C on the upstream side of the discharge electrode 40 in the exhaust gas passage 7. A cone-shaped guide member 21 and a plurality of (three in this example) swirl fins 22 that provide a swirl force in the radial direction to the exhaust gas flow are integrally provided on the upstream front surface 21 a of the cone-shaped guide member 21. . These swirling fins 22 are formed using a plate-like body that is curved in an arc shape that forms a part of a spiral shape, and in a state of projecting over a predetermined height from the upstream side front surface 21a, the conical guide member It arrange | positions so that it may spread in three directions from the center part of 21 to a radial direction.
Other configurations are the same as those of the first and second embodiments, and the same members are denoted by the same reference numerals.

  As described above, in the exhaust gas purifying apparatus 50 according to the third embodiment of the present invention, the plurality of swirling fins 22 for imparting a turning force in the radial direction to the exhaust gas flow are provided upstream of the discharge electrode 40 in the exhaust gas passage 7. Since the swirling fins 22 are provided, the exhaust gas flow and the PM are moved radially outward while being given a moving component in the circumferential direction, and the PM in the exhaust gas flow is supplied to the dust collection filter device 2. The reaching distance is further reduced, the amount of PM collected in the exhaust gas flowing in the exhaust gas passage 7 in the dust collection filter device 2 is further increased, the PM collection efficiency of the dust collection filter device 2 is improved, and the residual Purified gas with less PM can be obtained.

  While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes and modifications can be made based on the technical idea of the present invention.

It is a schematic sectional drawing which shows the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is the sectional view on the AA line of FIG. (A) is a schematic sectional drawing which shows the exhaust gas purification apparatus which concerns on 2nd Embodiment of this invention, (B) is the Z section enlarged view in (A). (A) is a schematic sectional drawing which shows the electric dust collector which concerns on 3rd Embodiment of this invention, (B) is the Y section enlarged view in (A), (C) is a W arrow view in (B). is there. It is a schematic sectional drawing which shows the example of the conventional electric dust collector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer shell 2 Dust collection filter apparatus 3 Discharge electrode discharge part 4 Discharge electrode main part 7 Exhaust gas passage 10, 10a Swirling flow formation pipe 11 Swirling flow 21 Cone-shaped guide member 22 Swirling fin 30 Ion wind 40 Discharge electrode 50 Exhaust gas purification apparatus

Claims (4)

A cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device and includes particulate matter. The exhaust gas passage through which the exhaust gas flows and the exhaust gas passage orthogonal to the exhaust gas flow between the dust collection filter device when a voltage is applied are installed in the exhaust gas passage in a direction crossing the exhaust gas passage. In an exhaust gas purification apparatus comprising a discharge electrode that generates an ionic wind that induces and forms a secondary flow in the direction of
An exhaust gas purifying apparatus, characterized in that an exhaust gas swirl forming tube that opens in a tangential direction with respect to the exhaust gas passage is provided in the outer shell located on the upstream side of the discharge electrode.   The exhaust gas purification apparatus according to claim 1, wherein the swirl flow forming pipe is provided such that an opening end to the exhaust gas passage is opposed to a center of the exhaust gas passage. A cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device and includes particulate matter. The exhaust gas passage through which the exhaust gas flows and the exhaust gas passage orthogonal to the exhaust gas flow between the dust collection filter device when a voltage is applied are installed in the exhaust gas passage in a direction crossing the exhaust gas passage. In an exhaust gas purification apparatus comprising a discharge electrode that generates an ionic wind that induces and forms a secondary flow in the direction of
In the exhaust gas passage, on the upstream side of the discharge electrode, a guide member for deflecting the exhaust gas flow toward the dust collecting filter device after colliding the exhaust gas flow is provided. apparatus. A cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device and includes particulate matter. The exhaust gas passage through which the exhaust gas flows and the exhaust gas passage orthogonal to the exhaust gas flow between the dust collection filter device when a voltage is applied are installed in the exhaust gas passage in a direction crossing the exhaust gas passage. In an exhaust gas purification apparatus comprising a discharge electrode that generates an ionic wind that induces and forms a secondary flow in the direction of
In the exhaust gas passage, on the upstream side of the discharge electrode, a swirl fin for providing a swirl force in the radial direction to the exhaust gas flow is provided.

Images