JP3924347B2 - Exhaust gas purification device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purification device, and more particularly to an exhaust gas purification device that can effectively reduce harmful components in exhaust gas.
[0002]
[Prior art]
Of the harmful components in the exhaust gas discharged from the vehicle engine, carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) are regulated as air pollutants. CO, HC, and NOx in the exhaust gas are all generated as a result of combustion of a mixture of fuel and air.
[0003]
In addition, in the case of a diesel engine, the generation of CO and HC is small, but NOx is a problem, and a part of the fuel is decomposed by high temperature, and black smoke (smoke) is discharged by liberation of carbon. There's a problem. Most of the NOx generated in the combustion chamber of the engine is nitric oxide (NO), and NO exhausted from the combustion chamber is oxidized into NOx in the atmosphere. The concentration of NO depends on the influence of the air-fuel ratio and the combustion temperature.
[0004]
In general, measures for reducing the generation of NOx in the diesel engine are performed by changing the shape of the combustion chamber or by retarding the fuel injection timing. Some exhaust systems employ various systems such as a three-way catalyst system using a vehicle catalyst and a redox catalyst system.
[0005]
[Problems to be solved by the invention]
However, in the case of diesel engines, exhaust gas regulations tend to be tightened, changing the shape of the combustion chamber, controlling the retarded fuel injection timing, and using various methods such as the three-way catalyst method and the oxidation-reduction catalyst method. Even if it is adopted, it is particularly difficult to sufficiently reduce NOx which is a problem, and it has become difficult to cope with the new exhaust gas regulations. Moreover, in order to deal with the exhaust gas regulations, there is a disadvantage that the structure becomes complicated.
[0006]
[Means for Solving the Problems]
Accordingly, the present invention provides an exhaust gas purification apparatus provided with a vehicle catalyst for purifying harmful components in exhaust gas discharged from an engine in order to eliminate the above-mentioned disadvantages, wherein the vehicle catalyst is made of a conductive material. Formed on the surface and coated with a catalytic substance on the surface, an upstream quartz tube fitted on the upstream outer peripheral surface of the carrier, and a downstream quartz fitted on the outer peripheral surface on the downstream side of the carrier And an insulating member fitted on the outer peripheral surface of the carrier between the upstream side quartz tube and the downstream side quartz tube, and the vehicle catalyst has an upstream end surface of the carrier. An electric circuit comprising: a connected plus discharge electrode; a minus discharge electrode connected to an end face on the downstream side of the carrier; and a power supply unit connected to the plus discharge electrode and the minus discharge electrode. This electrical circuit is Serial characterized by decomposing in the plasma state harmful components in the exhaust gas passing through the by supplying high current at high frequency carrier from the power supply unit as a power to the positive discharge electrode and the negative discharge electrode.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In this invention, harmful components in the exhaust gas discharged from the engine are in a plasma state, that is, the concentrations of positive ions and negative ions are substantially equal when supplied through an electric circuit when passing through the vehicle catalyst. As an electrically neutral group, it is decomposed. In addition, harmful components in the exhaust gas that have not turned into a plasma state are removed by the vehicle catalyst. As a result, harmful components in the exhaust gas are effectively reduced, and an existing vehicle catalyst is simply provided with an electric circuit, so that it is possible to cope with new exhaust gas regulations with a simple configuration and at a low cost. .
[0008]
【Example】
Embodiments of the present invention will be described in detail and specifically with reference to the drawings. 1 to 6 show an embodiment of the present invention. 1-3, 2 is the vehicle catalyst of an exhaust gas purification apparatus. This vehicle catalyst 2 is of a three-way catalyst type, and is a catalyst substance on the surface of a honeycomb-like (honeycomb-like) carrier 4 such as platinum (Pt), palladium (Pd), rhodium (Ro), etc. It is configured by coating. The vehicle catalyst 2 composed of the honeycomb-shaped carrier 4 has a relatively small exhaust resistance. The carrier 4 is made of a conductive material.
[0009]
On the outer peripheral surface of the carrier 4, an upstream quartz tube 6-1 is fitted upstream of the exhaust gas, and a downstream quartz tube 6-2 is fitted downstream of the exhaust gas.
[0010]
The vehicle catalyst 2 is provided with an electric circuit 8 that electrically decomposes harmful components in the exhaust gas into a plasma state. In other words, the positive discharge electrode 10-1 is connected to the upstream end face of the carrier 4. A negative discharge electrode 10-2 is connected to the downstream end face of the carrier 4.
[0011]
The plus side and minus side discharge electrodes 10-1 and 10-2 are made of, for example, a stainless steel wire having a diameter of 0.2 mm, and communicate with the power supply unit 12.
[0012]
The power source 12 supplies high-frequency and high-voltage current as power to the plus-side and minus-side discharge electrodes 10-1 and 10-2. When high frequency is applied to the positive and negative discharge electrodes 10-1 and 10-2, harmful components in the exhaust gas passing through the carrier 4 are in a plasma state, that is, the concentrations of positive ions and negative ions are substantially equal. As a whole, it becomes an electrically neutral group and is decomposed.
[0013]
On the outer peripheral surface of the carrier 4, an aluminum seal material 14 as an insulating member is fitted between the upstream side quartz tube 6-1 and the downstream side quartz tube 6-2. A ground electrode 16 is connected to the aluminum sealing material 14.
[0014]
Although not shown, the vehicle catalyst 2 is held by a catalyst cover.
[0015]
Next, the operation of this embodiment will be described.
[0016]
When electric power is supplied to the plus side and minus side discharge electrodes 10-1 and 10-2, harmful components in the exhaust gas passing through the carrier 4 enter a plasma state, that is, particularly nitric oxide (NO in the harmful components). ), Nitrogen dioxide (NO ₂ ), and nitrogen oxides (NOx), the concentrations of positive ions and negative ions are substantially equal to form an electrically neutral group as a whole, decomposed, and downstream Washed away. Thereby, NO, NO ₂ and NOx are reduced.
[0017]
Further, harmful components that have not been brought into the plasma state are removed by the carrier 4 as in the conventional case. Thereby, NO, NO ₂ and NOx are further reduced.
[0018]
That is, as shown in FIG. 4, as a gas sample, the exhaust gas flow rate is 2 liters / min, and at room temperature, nitrogen monoxide (NO) and nitrogen oxide (NOx) are about 800 ppm, oxygen (O ₂ ) is 10%, When carbon dioxide (CO ₂ ) is 10%, and as shown in FIG. 5, as a gas sample, the exhaust gas flow rate is 2 liters / min, and at room temperature, nitrogen monoxide (NO) and nitrogen oxides (NOx) Is about 600 ppm, oxygen (O ₂ ) is 10%, carbon dioxide (CO ₂ ) is 10%, and as shown in FIG. 6, the exhaust gas flow rate is 2 liters / min. As is apparent from the case where nitrogen monoxide (NO) and nitrogen oxide (NOx) are about 400 ppm, oxygen (O ₂ ) is 10%, and carbon dioxide (CO ₂ ) is 10%, the vehicle catalyst 2 Only with nitric oxide (NO) and nitrogen oxides (NOx), to a value nitrogen dioxide (NO _2), nitrogen oxides (NOx) is reduced (indicated by mark in black in FIGS. 4-6), in this embodiment, , NO, NO ₂ , NOx values (indicated by white marks in FIGS. 4 to 6) are considerably reduced.
[0019]
Moreover, since the generation of NO, NO ₂ , and NOx as harmful components can be reduced simply by attaching the electric circuit 8 to the conventional vehicle catalyst 2, the configuration is simple and inexpensive, and new exhaust gas regulations can be achieved. Can be dealt with.
[0020]
【The invention's effect】
As is apparent from the above detailed description, according to the present invention, the vehicle catalyst is provided with an electric circuit that electrically decomposes the harmful components in the exhaust gas into a plasma state, thereby effectively removing the harmful components in the exhaust gas. Can be reduced.
[0021]
In addition, since only an electric circuit is provided for the vehicle catalyst, it is possible to cope with new exhaust gas regulations with a simple configuration and at a low cost.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an exhaust gas purification apparatus.
FIG. 2 is a partial cross-sectional view of the vehicle catalyst of FIG.
FIG. 3 is a front view of a vehicle catalyst.
FIG. 4 is a diagram showing a reduced state of harmful components when NO is about 800 ppm.
FIG. 5 is a diagram showing a reduced state of harmful components when NO is about 600 ppm.
FIG. 6 is a diagram showing a reduced state of harmful components when NO is about 400 ppm.
[Explanation of symbols]
2 Vehicle catalyst 4 Carrier 6 Quartz tube 8 Electrical circuit 10 Discharge electrode 12 Power source 14 Aluminum seal material 16 Ground electrode

Claims (1)

In the exhaust gas purification apparatus provided with the vehicle catalyst for purifying harmful components in the exhaust gas discharged from the engine, the vehicle catalyst is formed of a conductive material and has a surface coated with a catalytic substance, An upstream quartz tube fitted to the upstream outer peripheral surface of the carrier; a downstream quartz tube fitted to the downstream outer circumferential surface of the carrier; the upstream quartz tube and the downstream quartz tube; Between the positive electrode connected to the upstream end surface of the carrier and the downstream side of the carrier. Provided is an electric circuit comprising a negative discharge electrode connected to an end surface, and the positive discharge electrode and a power source connected to the negative discharge electrode. The electric circuit is connected to the positive discharge from the power source. Electrode and negative Exhaust gas purification apparatus characterized by decomposing the harmful components in the exhaust gas passing through said by supplying high current at high frequency carrier in the plasma state in the discharge electrodes as power.

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