JP2005307754A - Exhaust gas purifying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas purifying device capable of treating exhaust gas by applying a high voltage and suppressing an influence of vibration and thermal expansion. <P>SOLUTION: This exhaust gas purifying device purifies exhaust gas supplied between an outer peripheral electrode 10 and an internal electrode 20 inserted into a space surrounded by the outer peripheral electrode 10 by applying a high voltage between both electrodes 10 and 20. A cavity 30 is formed between a feeding terminal 14 fixed to a predetermined position and the internal electrode 20 to feed electricity into the internal electrode 20 by the dielectric breakdown of the cavity 30 caused by the application of a high voltage to a feeding terminal 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas purification apparatus that purifies exhaust gas of an internal combustion engine by applying a high voltage.

As a technique for purifying exhaust gas of an internal combustion engine such as a vehicle, in recent years, a predetermined voltage such as NOx in exhaust gas is activated by applying a high voltage between a plurality of electrodes installed in the exhaust gas flow path, An exhaust gas purifying apparatus that promotes the reaction and converts it into a substance such as N ₂ has been proposed. For example, in Patent Document 1, a honeycomb carrier catalyst is disposed between flat electrodes to constitute a high voltage processing unit, and a DC voltage supplied from a battery is converted into a high voltage AC voltage by a high voltage power generation unit. Is applied between the flat plate electrodes of the high-voltage processing section to generate corona discharge and promote an NOx reaction to purify the exhaust gas. This exhaust gas purification device is installed in the exhaust path of a diesel engine and purifies exhaust gas from the engine.

On the other hand, it has a cylindrical outer peripheral electrode and a rod-shaped center electrode extending along the axis of the outer peripheral electrode, and purifies the exhaust gas that passes through it using plasma generated by applying a high voltage between both electrodes. In other words, a so-called permeation type exhaust gas purifying apparatus has been proposed. In such an apparatus, a substance such as NOx in the exhaust gas passing through is converted into N _{2 and the} like, and PM (particulate matter) in the supplied exhaust gas is charged by discharge from the center electrode, It is adsorbed on the outer peripheral electrode side having the opposite polarity, and is incinerated by heat generated with application of a high voltage. Such a transmission type device has an advantage that the pressure loss due to the exhaust resistance is small as compared with a filtration type device in which the exhaust gas does not pass through the fiber filter.

Japanese Patent No. 3147193

  By the way, in this kind of exhaust gas purifying apparatus, there is still a problem in maintaining the performance of the apparatus. For example, in a structure in which a power supply terminal fixed to the outer peripheral electrode and the inner electrode are rigidly fixed by welding or the like in order to supply power to the inner electrode arranged on the axis of the outer peripheral electrode, Connection points are likely to break due to thermal expansion, and improvements are required.

  SUMMARY OF THE INVENTION An object of the present invention is to provide means capable of stably performing discharge by suppressing the influence of vibration and thermal expansion in an exhaust gas purification apparatus that processes exhaust gas by applying a high voltage.

  The first aspect of the present invention purifies the exhaust gas supplied between the two electrodes by applying a high voltage between the outer electrode and the inner electrode inserted in the space surrounded by the outer electrode. In the exhaust gas purifying apparatus, a gap is provided between the power supply terminal fixed at a predetermined position and the internal electrode, and power is supplied to the internal electrode by dielectric breakdown of the gap due to application of a high voltage to the power supply terminal. It is an exhaust gas purification device characterized by being performed.

  In the first aspect of the present invention, since the gap is provided between the power supply terminal and the internal electrode, the mechanical interaction between the power supply terminal and the internal electrode is suppressed, thereby suppressing the influence of vibration and thermal expansion. Can do.

  The second aspect of the present invention purifies the exhaust gas supplied between the two electrodes by applying a high voltage between the outer electrode and the inner electrode inserted in the space surrounded by the outer electrode. In the exhaust gas purifying apparatus, a gap is provided between the power supply terminal fixed at a predetermined position and the internal electrode, and the power supply terminal and the internal electrode are coupled to each other by a flexible conductive wire. An exhaust gas purification device characterized by the above.

  In the second aspect of the present invention, a gap is provided between the power supply terminal and the internal electrode, and the power supply terminal and the internal electrode are coupled to each other by a flexible conductive wire. While mechanical interaction is suppressed by the presence of the air gap, energy loss during power feeding can be suppressed by the conductive wire.

  A third aspect of the present invention is the exhaust gas purification apparatus according to claim 1 or 2, wherein the internal electrode is slidable with respect to at least one of the plurality of support members that support the internal electrode. It is an exhaust gas purification apparatus characterized by being.

  In the third aspect of the present invention, since the internal electrode is slidable with respect to any one of the support members, the longitudinal extension due to the thermal expansion of the internal electrode is allowed, thereby suppressing the deformation of the internal electrode.

  According to a fourth aspect of the present invention, there is provided an exhaust gas purifying apparatus according to claim 3, further comprising a biasing means for constantly biasing the internal electrode in its extending direction.

  In the fourth aspect of the present invention, since the urging means constantly urges the internal electrode in the extending direction, the position and shape of the internal electrode can be maintained.

  The fifth aspect of the present invention is the exhaust gas purification apparatus according to claim 4, wherein the urging means urges the internal electrode in a direction away from the power supply terminal. It is.

  In the fifth aspect of the present invention, the urging means urges the internal electrode in a direction away from the power supply terminal, so that interference between the internal electrode and the power supply terminal can be suppressed according to the urging force.

  A sixth aspect of the present invention is the exhaust gas purifying apparatus according to claim 5, wherein the internal electrode in a direction away from the power supply terminal is positioned closer to the power supply terminal than a biasing point by the biasing means. An exhaust gas purifying apparatus further comprising a restricting means for restricting movement.

  In the sixth aspect of the present invention, the relative position between the power supply terminal and the internal electrode can be positioned by the regulating means.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an exhaust gas purification apparatus 1 according to a first embodiment of the present invention is applied to a vehicle, and is inserted into the purification container 10 having a function as an outer peripheral electrode in the present invention. It is configured as a plasma reactor or a corona reactor including the internal electrode 20.

  The purification container 10 has a substantially cylindrical shape, and includes throat portions 10a and 10b having a diameter smaller than that of the main body at its upstream and downstream ends. Each of the throat portions 10a and 10b includes a flange 10c. The material of the purification container 10 is preferably a heat-resistant conductive material such as SUS. A power supply terminal 14 including an electrode seat 11, an insulator sleeve 12 and a rod-shaped electrode 13 is fixed to the purification container 10 downward in the drawing.

  The internal electrode 20 has a rod shape, and is supported on the purification container 10 by a support column 21 extending in the vertical direction in the drawing in the vicinity of the upstream and downstream ends. The internal electrode 20 is inserted into the through hole 21 a of the support column 21, and is thereby slidable in the axial direction with respect to the support column 21. The material of the internal electrode 20 is preferably a heat-resistant conductive material such as SUS or tungsten. In addition, although it is desirable for the material of the internal electrode 20 to be the same as the material of the purification container 10, in order to suppress the shift | offset | difference of the elongation dimension resulting from the difference in the thermal expansion coefficient between both, both need to use the same material. There is no. In addition, although the internal electrode 20 in the present embodiment is substantially rigid as a whole, the whole or a part of the internal electrode in the present invention (especially the intermediate region sandwiched between the columns 21) can be a conductive wire or the like. It may be a flexible body. The material of the column 21 is preferably a material having high heat resistance and excellent electrical insulation, such as alumina or ceramics.

  A stopper 20 a is fixed near the upstream end of the internal electrode 20. In the vicinity of the downstream end of the internal electrode 20, a stopper 20 b is fixed with a coil spring 22 sandwiched between the column 21. The internal electrode 20 is constantly urged by a coil spring 22 toward the downstream side, which is the direction in which the internal electrode 20 extends and away from the power supply terminal 14. As shown in FIG. 2, the internal electrode 20 is disposed at the axial center of the purification container 10.

  The lower end of the power supply terminal 14 is an extension of the axis of the internal electrode 20 and faces the end face on the upstream side of the internal electrode 20, and a gap 30 is provided between the power supply terminal 14 and the internal electrode 20. ing. The dimension of the air gap 30, that is, the distance between the power supply terminal 14 and the internal electrode 20 is such a value that power is supplied to the internal electrode 20 due to dielectric breakdown of the air gap 30 due to application of a high voltage to the power supply terminal 14. In addition, the power supply terminal 14 and the internal electrode 20 are set to values that do not interfere with each other under vibration during operation.

In the first embodiment configured as described above, the purification container 10 is electrically grounded, and a DC pulse voltage is applied to the power supply terminal 14. In operation, power is supplied to the internal electrode 20 by dielectric breakdown of the air gap 30 due to application of a high voltage to the power supply terminal 14. When exhaust gas from the engine is supplied in the direction of arrow A in the figure, a plasma state is generated by discharge such as corona discharge between the purification container 10 and the internal electrode 20, and a predetermined substance such as NOx in the exhaust gas is activated. And the reaction is promoted and converted into a substance such as N ₂ . Further, PM in the supplied exhaust gas is charged by the discharge from the internal electrode 20 and is adsorbed by the purification container 10 due to the interaction with the electric field between the internal electrode 20 and the purification container 10, and accompanying the application of a high voltage. Combustion or oxidation is accelerated by the generated heat.

  Here, in this embodiment, since the air gap 30 is provided between the power supply terminal 14 and the internal electrode 20, the mechanical interaction between the power supply terminal 14 and the internal electrode 20 is suppressed, thereby being transmitted from the engine or It is possible to suppress the influence of vibration given as the vehicle body travels, and the influence of thermal expansion due to the amount of heat of exhaust gas and the amount of heat during discharge.

  Further, in this embodiment, since the internal electrode 20 is slidable with respect to the support column 21 that is a support member, the longitudinal extension due to thermal expansion of the internal electrode 20 is allowed, and the coil spring 22 that is a biasing means is provided. Since the internal electrode 20 is always urged in the extending direction, the position and shape of the internal electrode 20 can be maintained, deformation of the internal electrode 20, particularly sagging due to the extension can be suppressed, and tension of the internal electrode 20 can be suppressed. The play during operation can be suppressed by maintaining the state, and the bias of the discharge path and the uneven wear caused by these can be suppressed.

  In this embodiment, the coil spring 22 urges the internal electrode 20 in a direction away from the power supply terminal 14, so that the upstream end of the internal electrode 20 and the power supply terminal 14 correspond to the urging force. Interference can be suppressed. Further, among the plurality of support pillars 21, a stopper 20 a (regulating means) provided in association with the support pillar 21 and the internal electrode 14 provided at a position closer to the power feeding terminal 14 than the biasing point by the coil spring 22, Since the movement of the internal electrode 20 away from the power supply terminal 14 is restricted, the relative position between the power supply terminal 14 and the internal electrode 20 can be accurately positioned.

  Next, a second embodiment will be described. In the exhaust gas purifying apparatus 101 of the second embodiment shown in FIG. 3, a gap 130 is provided between the power supply terminal 114 fixed to a predetermined position and the internal electrode 20, and the power supply terminal 114 and the internal electrode 20 can be connected. The flexible conductive wires 140 are connected to each other.

  The power supply terminal 114 in the second embodiment includes an electrode seat 111, an insulator sleeve 112, and a rod-shaped electrode 113. The length of the rod-shaped electrode 113 is shorter than that of the rod-shaped electrode 13 in the first embodiment. Thus, a gap 130 is formed between the tip of the rod-shaped electrode 113 and the upstream end of the internal electrode 20. The tip of the rod-shaped electrode 113 and the upstream end of the internal electrode 20 are coupled by a coiled conductive wire 140. Since the remaining configuration in the second embodiment is the same as that in the first embodiment, the same reference numerals are used and detailed description thereof is omitted.

  In the second embodiment configured as described above, the purification container 10 is electrically grounded, while a DC pulse voltage is applied to the power supply terminal 114. In operation, power is supplied from the power supply terminal 114 to the internal electrode 20 by conduction through the conductive wire 140. When the exhaust gas from the engine is supplied in the direction of arrow A in the figure, the exhaust gas is treated by a discharge such as corona discharge between the purification container 10 and the internal electrode 20.

  Therefore, in the second embodiment, since the gap 130 is provided between the power supply terminal 114 and the internal electrode 20, mechanical interaction between the power supply terminal 114 and the internal electrode 20 is suppressed, thereby causing vibration and heat. The same effects as in the first embodiment, such as the ability to suppress the influence of expansion, are produced. In the present embodiment, since the power supply terminal 114 and the internal electrode 20 are coupled to each other by the flexible conductive wire 140, energy loss during power supply can be suppressed by the conductive wire 140.

  In the second embodiment, since the conductive wire 140 has a coil shape, the relative displacement between the power supply terminal 114 and the internal electrode 20 can be allowed in a wide range. However, the conductive wire in the present invention is not limited to the coil shape. Various shapes or structures having flexibility such that the power supply terminal 114 and the internal electrode 20 can be electrically connected while allowing relative displacement between the power supply terminal 114 and the internal electrode 20 can be adopted.

  The present invention is not limited to the aspects described in the above embodiments, and various modifications can be made. For example, in each of the above-described embodiments, the internal electrode 20 is slidable with respect to the columns 21 and 21, and the internal electrode 20 is positioned by bringing the stopper 20 a at the upstream end of the internal electrode 20 into contact with the column 21. Although the coil spring 22 is interposed only at the downstream end, the upstream end of the internal electrode 20 may be fixed to the column, and the coil spring may be provided at both ends of the internal electrode 20. Good. Further, although the stopper 20a is provided integrally with the internal electrode 20, a restricting means for restricting the movement of the internal electrode 20 may be provided on another member such as the column 21. Further, the shape and the number of support columns for supporting the internal electrode 20 are also arbitrary.

  In addition, the configuration of the high-voltage processing unit in the present invention is not limited to the aspect of the above-described embodiment. For example, a peripheral electrode separate from the purification container is provided in the purification container, a plurality of peripheral electrodes are provided, and the peripheral electrode is surrounded. Various types of materials that can modify exhaust gas by the action of electric power can be used, regardless of whether plasma is used or whether PM is filtered, such as by installing a honeycomb structure such as ceramics in the open space. It belongs to the category of the present invention.

It is a side view showing the outline of the exhaust gas purification device concerning a 1st embodiment of the present invention. 1 is a front view of an exhaust gas purification apparatus according to a first embodiment of the present invention. It is a side view which shows the outline of the exhaust gas purification apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 10 Purification container 13,113 Bar-shaped electrode 20 Internal electrode 20a, 20b Stopper 21 Strut 22 Coil spring 30, 130 Air gap 140 Conductive wire

Claims (6)

In the exhaust gas purifying apparatus for purifying the exhaust gas supplied between the two electrodes by applying a high voltage between the outer peripheral electrode and the internal electrode inserted into the space surrounded by the outer peripheral electrode,
A gap is provided between the power supply terminal fixed at a predetermined position and the internal electrode, and power is supplied to the internal electrode by dielectric breakdown of the gap due to application of a high voltage to the power supply terminal. Exhaust gas purification device. In the exhaust gas purifying apparatus for purifying the exhaust gas supplied between the two electrodes by applying a high voltage between the outer peripheral electrode and the internal electrode inserted into the space surrounded by the outer peripheral electrode,
Exhaust gas purification characterized in that a gap is provided between the power supply terminal fixed at a predetermined position and the internal electrode, and the power supply terminal and the internal electrode are coupled to each other by a flexible conductive wire. apparatus. The exhaust gas purifying device according to claim 1 or 2,
The exhaust gas purifying apparatus, wherein the internal electrode is slidable with respect to at least one of the plurality of support members that support the internal electrode. An exhaust gas purification device according to claim 3,
An exhaust gas purifying apparatus, further comprising a biasing means for constantly biasing the internal electrode in its extending direction. An exhaust gas purification device according to claim 4,
The exhaust gas purification apparatus according to claim 1, wherein the biasing means biases the internal electrode in a direction away from the power feeding terminal. An exhaust gas purification apparatus according to claim 5,
An exhaust gas purifying apparatus, further comprising a restricting means for restricting movement of the internal electrode in a direction away from the power supply terminal at a position closer to the power supply terminal than an urging point by the urging means.

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