JPS63268911A - Exhaust purifier for engine - Google Patents

Abstract

PURPOSE:To aim at improving dissociation and elimination effect of NOx is exhaust by providing an electrode holding member consisting of porous insulating material and including honeycomb passages in an exhaust passage and providing conductive bodies in the honeycomb passages. CONSTITUTION:An electrode holding member consisting of porous insulating material and including many honeycomb passages 6. In the honeycomb passages 6 are provided conductive bodies 4. With the conductive bodies 4 is connected a high voltage generator 5. Contacting area and duration between exhaust and a discharge field are expanded by this, and dissociation and elimination effect of NOx in exhaust can thus be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine exhaust purification device that utilizes a silent discharge field.

(Prior art) Gasoline engine or diesel engine (hereinafter referred to as
In the exhaust gas of an engine (simply referred to as an engine), t=n(-斥中社al)r, ni-'mm Illumisong 11(C (hydrogen 9ide), NOX (nitrogen oxide), etc. are naturally present. Of these, nitrogen oxides (NOx) are the main cause of photochemical smog, and are said to be harmless.

Therefore, various methods have been tried in the past in order to remove this nitrogen oxide NOX. For example, methods have been adopted in which harmful gases are reduced to harmlessness using a catalytic converter, but with this reduction method, 0. The problem remains that when there is a sufficient amount of nitrogen oxide NOX, it may not be possible to remove the nitrogen oxide NOX.

On the other hand, in recent years, research has been progressing on methods of using electrical energy to remove nitrogen oxides (NOx). There is a report that nitrogen oxides (NOx) are decomposed into 02 and N2 by the discharge generated inside the engine. A system has already been proposed in which a dissociation cylinder is connected to the dissection cylinder, and the dissociation cylinder in this case consists of a corona discharge needle protruding from the peripheral wall of the dissociation cylinder in the axial direction, and a center disposed at the axial center. It is constructed so as to cause a corona discharge between it and the pole (see Japanese Unexamined Patent Publication No. 31615/1983).

(Problems to be Solved by the Invention) In the case of the above-mentioned known example, nitrogen oxide NOx is dissociated by a corona discharge field in the dissociation cylinder connected to the exhaust pipe, but the exhaust flow in the discharge field is Since no measures have been taken to prevent this, that is, to increase the contact area between the discharge field and the exhaust gas, there is a risk that the dissociation and removal of nitrogen oxides NOx will be insufficient.

The present invention has been made in view of the above points, and aims to make the discharge field multilayered and reduce the exhaust flow velocity, thereby increasing the contact area and time between the discharge field and the exhaust gas, and thereby reducing nitrogen oxides. The purpose is to increase the dissociation and removal effect of NOx.

(Means for solving the problem) In the present invention, as a means for solving the above problem,
An electrode support member made of a porous insulating material and having a large number of honeycomb-shaped passages extending in the exhaust flow direction is disposed in the exhaust passage through which exhaust gas from the engine flows. The passage is provided with a conductor that acts as a discharge electrode.

(Function) In the present invention, the following effects can be obtained by the two-legged means.

That is, due to the porous structure disposed in the exhaust passage (a conductor acting as a discharge electrode is provided in the honeycomb-shaped passage of the electrode supporting member consisting of four groups), the honeycomb 1 is disposed between the honeycomb-shaped passages. When a silent discharge phenomenon occurs and a multilayered silent discharge field is generated, the exhaust gases flowing through the honeycomb-shaped passages described in 1iii. Since the exhaust flow velocity is lowered due to the +1 material), the contact area and time between the exhaust and the discharge field are increased, and the discharge intensity is also increased. The effect of dissociating and removing the nitrogen oxides NOx contained therein is greatly improved. Further, since the conductor acting as the discharge electrode is provided in the honeycomb-shaped passage of the electrode supporting member, the conductor can be easily installed and the stability of the electrode gap can be easily ensured.

(Embodiments) Hereinafter, some preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment I FIGS. 1 and 2 show an engine exhaust purification device according to Embodiment 1 of the present invention.

The exhaust purification device according to this embodiment is as shown in FIG.
An electrode supporting member 3, which is disposed in a discharge chamber 2a formed in the middle of an exhaust passage 2 from an engine l and has a large number of honeycomb-shaped passages 6, 6, extending in the exhaust flow direction; Conductors 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 5, 4, 4 , 4 each of which are provided in the comb-like passages 6, 6, .
It is constituted by a high voltage generator 5 that applies a high voltage to these conductors 4, 4, . . . Said T,
As the electrode supporting member 3, a monolithic carrier for a catalyst carrier made of a porous insulating material is used.

The electrode carrier P! j ;'! l< The population side and outlet side of the honeycomb-shaped passages 6.6 in IA3 are alternately closed by plugs 7.8 made of an insulating material, so that the exhaust gas G flowing through the honeycomb-shaped passages 6 can enter the cells. wall 6
a (passes through the porous insulation (composed of four materials) and flows into the adjacent honeycomb-shaped passage 6). Exhaust G follows an extremely long distribution route,
The flow velocity will also have to be significantly reduced.

Then, behind the honeycomb-like passages 6, 6..., a person [
the cell wall 6 of the passage which is closed on one side by a plug 7;
A is provided with a conductor 4 that acts as a discharge electrode, and in this embodiment, the conductor 4 is made of an alumina coating 11Δ containing a noble metal such as platinum. Precious metals such as platinum in the alumina coach ink layer not only improves conductivity but also acts as a catalyst to help reduce harmful substances such as carbon monoxide, which is contained in exhaust gas. act. Note that the conductive substance contained in the alumina coating layer is not limited to noble metals that have catalytic activity as in this embodiment, but conductive substances that do not have catalytic activity may be used.

The conductors 4, 4, . . . are connected to the high voltage generator 5 so that positive and negative electrodes are alternately arranged. Thus, by applying a high voltage from the high voltage generator 4 to the conductors 4, 4, a silent discharge is generated between the conductors 4, 4, and so on.
'[Nitrogen oxide NOX in the exhaust gas flowing through the discharge field generated by oxygen 0. and nitrogen Nt. Note that oxygen 02 after dissociation becomes nitrogen N! due to the difference in affinity between molecules. without recombining with
It combines with carbon monoxide CO in the exhaust gas G to become harmless carbon dioxide CO7 and is discharged from the system. As a result, the harmless nitrogen N generated by the dissociation of nitrogen oxide NOx remains in the system as it is. It will be discharged outside. Furthermore, since noble metals such as platinum contained in the conductor 4 act as a catalyst for reduction, carbon monoxide co in the exhaust gas G and hydrocarbons 11
Therefore, the purification of c must be done at the same time.

Next, we will explain the operation of the exhaust purification device according to the illustrated embodiment.
I can explain.

Exhaust gas G generated by the operation of the engine I passes through the exhaust passage 2 and reaches the discharge chamber 2a. In the discharge chamber 2a,
A conductor 4 to which a high voltage is applied by a high voltage generator 5.
4...A discharge field is generated by silent discharge (I L is expected to occur).Therefore, the harmful nitrogen oxide NOx contained in the exhaust gas G flowing into the discharge chamber 2a is considered to be a serious culprit. Due to the action of the discharge field, oxygen Ot and nitrogen N dissociate into ttl.
, you will be disappointed. And oxygen O3 after solution M is
Due to the difference in affinity between molecules, it does not recombine with nitrogen N2, but combines with carbon monoxide CO in exhaust gas G, becomes harmless carbon dioxide CO7, and is discharged from the system. Thus, harmless nitrogen N, produced by the dissociation of nitrogen oxide NOX, is
It will be discharged from the system in that state. However, in the case of this embodiment, since the serious conductors 4.4... are composed of an alumina coating layer containing a precious metal having a catalytic action, some of the exhaust gas G in the process of passing through the electrode support member 3 is The reduction of carbon oxide GO1 and hydrocarbon HC will be carried out. Therefore, an extremely high purifying effect on exhaust gas G is exhibited.

Furthermore, in the case of this embodiment, a silent discharge phenomenon occurs between the honeycomb-shaped passages 6, 6, .・The flow of the exhaust gas G and As the area and time of contact with the discharge field are increased, the intensity of the discharge is also increased, and the effect of dissociating and removing nitrogen oxides NOx in the exhaust gas is greatly improved.

In addition, since the conductor 4 that acts as a discharge electrode is made of a layer of coated aluminum coated on the cell wall 63 of the honeycomb-like passage 6 in the electrode support member 3, the conductor 4 can be easily installed. This makes it easier to maintain the stability of the electrode gap.

Embodiment 2 FIG. 3 shows an engine exhaust purification device according to Embodiment 2 of the present invention.

In this embodiment, the electrode supporting member 3 is a diesel particulate filter (hereinafter referred to as I), which is a known filter member for purifying particulates (i.e., fine particulate emissions) in the exhaust gas G. ) is used. The D I) F b is made of a porous insulating material and has a structure with honeycomb-shaped passages 6.6 extending in the exhaust flow direction, and the artificial side of these honeycomb-shaped passages 6.6... And on the outlet side, plugs 7, 8 are alternately provided as in the first embodiment. and n: i honeycomb-like passage 6.
A linear conductor 4.6 which acts as a discharge electrode is placed in the passage whose inlet side is closed by the plug 7. 1... are provided with their ends supported by the insulating material plug 7. The conductors 4, 4, . . . are connected to the high voltage generator 5 so that positive and negative electrodes are alternately arranged. In addition to the above-described embodiments, the conductors 4, 4, etc. may be installed at the intersections of the cell walls, or embedded in the honeycomb-like passages 6 using an insulating material. You may. In addition, the conductors 4.4... in this example do not have a catalytic effect, but are made of a conductive material that has a catalytic effect, such as IC, Co
Of course, it is also possible to remove . The other configurations and operations are the same as those of the first embodiment, so their explanations will be omitted.

It goes without saying that the present invention is not limited to the configuration of the above-described embodiments, and that the design can be changed as appropriate without departing from the gist of the invention.

(Effects of the Invention) As mentioned above, according to the present invention, an electrode supporting Cf is provided in which a large number of honeycomb-shaped passages made of a porous insulating material and extending in the exhaust flow direction are formed in the exhaust passage through which exhaust gas from the engine flows. At the same time, a staggered conductor that acts as a discharge electrode is provided in the honeycomb-shaped passages of the electrode supporting member, so a silent discharge phenomenon occurs between the honeycomb-shaped passages, and a multilayered silent discharge field is generated. At the same time, the flow rate of the exhaust gas flowing through the honeycomb-like passages is reduced by mutual communication (because the electrode supporting member is made of a porous insulating material). In addition to increasing the contact area and time between the discharge field and the discharge field, the discharge intensity is also increased, which has the excellent effect of greatly improving the dissociation and removal effect of nitrogen oxide NOx in the exhaust gas.

In addition, since the conductor that acts as a discharge electrode is provided in the honeycomb-shaped passage of the electrode support member, it is easy to install the conductor and it is also easy to ensure the stability of the electrode gap. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing an engine exhaust purification device according to Embodiment 1 of the present invention, FIG. 2 is an enlarged sectional view of an electrode supporting member in the exhaust gas purification device of FIG. 1, and FIG. 3 is an inventive FIG. 2 is a cross-sectional view of main parts schematically showing an engine exhaust purification device according to a second embodiment of the present invention. l...Engine 2...Exhaust passage 3...Electrode supporting member 4...Conductor

Claims (1)

[Claims] 1. An electrode support member made of a porous insulating material and having a large number of honeycomb-shaped passages extending in the exhaust flow direction is disposed in the exhaust passage through which exhaust gas from the engine flows;
An exhaust gas purification device for an engine, characterized in that a conductor acting as a discharge electrode is provided in the honeycomb-shaped passage of the electrode supporting member.