KR20050002688A - Automobile gas scrubber of the dry discharge filter deposited with catalytic thin films - Google Patents

Abstract

PURPOSE: An automobile exhaust gas scrubber of a high-voltage dry discharge filter deposited with catalytic thin films is provided to stabilize discharged and dissolved radial by jetting the ion gas on to the surface of a catalytic plate and functioning a catalytic metal layer as a micro catalyst on a patterned surface. CONSTITUTION: In post-processing the residual gas after purifying the exhaust gas of a diesel vehicle by a primary ternary catalyst through a high-voltage and low-current dry discharge filter, an automobile exhaust gas scrubber has a catalytic plate(22) having a patterned shape formed by vacuum-metalizing multi-layer thin films of a catalytic agent and minimizes the loss of pressure by corresponding the discharge diffusion direction of the gas to the gas flow direction. Plural pairs of gas passage holes(6) of a positive needle(4) and a negative plate(3) are aligned in one direction on the discharge filter.

Description

Automotive gas scrubber of the dry discharge filter deposited with catalytic thin films}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for purifying exhaust gas of a vehicle having a catalyst thin film high voltage dry discharge filter. In particular, the combustion gas remaining after the three-way catalyst purification of a diesel vehicle is decomposed through a discharge filter having a surface on which a catalyst material is deposited. It provides the effect of preventing air pollution of air. A high voltage discharge circuit is attached between the exhaust gas purification device and the car battery power supply to discharge the high voltage. The residual exhaust gas that has passed through the three-way catalyst purification device passes through the discharge region between the anode and the cathode and is decomposed into discharge energy. The present invention relates to an automobile exhaust gas purifying apparatus having a catalytic thin film type high voltage dry discharge filter for purifying exhaust gas by converting ion exhaust gas into a molecular structure stabilized by a catalytic function at the same time.

Due to rapidly increasing air pollution regulations, automobile and hazardous exhaust gas producers are making great efforts to remove harmful components of exhaust gas. The three-way catalytic device, a conventional exhaust gas purification device currently used for automobile exhaust gas purification, has a honeycomb structure using ceramics and an alumina coating on its surface, and the catalyst device is activated to have a full purification function. Since the catalyst device must be heated before gas purification because it should be about 250 degrees Celsius, residual toxic gases after purification, such as low purification efficiency at the beginning of the engine and difference in exhaust gas purification ability according to air-fuel ratio, are generated. have. Therefore, many attempts have been made to remove the exhaust gas by electric discharge to compensate for the problems of the three-way catalytic device.

Electrical discharge methods include plasma discharge methods and corona discharge methods. Plasma system forms a plasma by passing a pulse having a radio frequency (RF) or microwave frequency through the exhaust gas or ionizing the gas by forming a high current magnetic field in the exhaust gas, and decomposing the exhaust gas, There is a drawback to consuming. Therefore, this plasma discharge method is not suitable as a vehicle exhaust gas purifier because it is a heavy burden on a battery operated automobile electric system, and is mainly used to cool a small amount of gas at low process pressure below atmospheric pressure in a vacuum reactor reactor of a semiconductor. As a form of decomposition in the state, it is widely used for special purposes in the semiconductor industry.

On the other hand, the corona discharge method is a direct current discharge, and when a high voltage is applied between two electrodes, only a strong part of the electric field has conductivity before emitting a spark, and requires a high voltage. It consists of a hole-shaped cathode electrode. Exhaust gas is decomposed by the high voltage between the two electrodes to cause a corona discharge to utilize the exhaust purification function. Many embodiments of the purifier applying the high voltage of the corona discharge method has been attempted, but the purifier shape requires a large current flow to increase the discharge efficiency, resulting in deterioration between the two electrode plates, exhaust Increasing the residence time by reducing the flow rate of the gas not only increases the back pressure, but also poses a safety risk in application to automobiles due to high power.

Therefore, since the conventional plasma method requires high power to form a high current magnetic field in the exhaust gas, an additional device such as a high frequency coil must be installed, and the conventional corona method is a pole plate due to a large amount of exhaust gas ionization and discharge. In order to prevent a sudden drop in damage and discharge efficiency, and to increase the reaction rate, it is necessary to purify in consideration of the flow rate change, and thus, there is a development problem of reducing the exhaust gas pressure rise while increasing the residence time.

The present invention has been made in view of the above-described conventional technical problem, and an object of the present invention is to use a conventional vehicle battery as it is and pass a residual gas passed through a three-way catalyst device into a catalyst plate on which a catalytic metal thin film is deposited and a high voltage dry discharge filter. The present invention provides a method for an apparatus having a function of efficiently removing exhaust gas regardless of an operating temperature or an operating time from an initial stage of start-up.

In achieving the above object, the high voltage dry discharge device according to the present invention uses a pair of positive electrode pins and perforated negative electrode plates having a benzene net structure to charge high voltage therebetween, It is an apparatus that is ionized by discharge and at the same time an exhaust gas in an ionic state is purified on the surface of a catalyst plate on which a catalytic metal thin film is deposited. The catalytic metal thin film is formed by depositing and fine pattern shape by using a vacuum deposition apparatus in a micromachining process to form an electrode surface having a structure that maximizes the catalyst phenomenon, and the exhaust gas passes efficiently through several pairs of discharge filters. It is characterized by reducing the increase in back pressure by having an optimal structure that is purified and minimizes flow resistance.

1 is a configuration of the exhaust process of the purification reactor using a conventional multi-porous porous plate.

Figure 2 is a cross-sectional view of the discharge plate of the exhaust purification apparatus by a conventional porous porous corona discharge.

3 is a block diagram of an exhaust gas post-treatment apparatus using a conventional discharge device.

Figure 4 is an overall schematic diagram of the exhaust purification apparatus by the high voltage discharge in the present invention

Fig. 5 is a sectional view of the high voltage discharge filter of the first embodiment in the present invention.

Figure 6 is a detailed view of the benzene net structure of the discharge plate in the present invention.

7 is a cross-sectional view of the catalyst thin film high voltage discharge filter of the second embodiment in the present invention.

8 is a schematic view of a catalyst plate on which a multilayer catalyst thin film is deposited in the present invention.

Figure 9 is a partial cross-sectional view of the catalyst plate in which the multilayer catalyst thin film is deposited in the present invention.

10 is a block diagram of a high voltage circuit in the present invention.

Figure 11 is a comparison of performance according to the soot concentration in the present invention.

(Explanation of symbols for main parts of drawing)

1: Exhaust gas injection port 2: Positive electrode plate

3: negative electrode plate 4: positive electrode

5: electrode connection part 6: gas passage hole

7: Plasma reactor 8: Cathode electrode

9: positive pole park 10: air nozzle

11: Separator 12: Exhaust gas outlet

13: high voltage generator 14: inner housing

15: outer housing 16: insulation

17: Bolt fastening part 18: Positive electrode

19: electrode support rod 20: insulator

21: coated wire 22: catalyst plate

23: catalytic metal deposition layer 24: alumina plate

25: thin film layer for hot plate 26: rhodium thin film layer

27: palladium thin film layer 28: platinum thin film layer

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. These preferred embodiments enable a better understanding of the objects, features and advantages of the present invention. Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the exhaust gas purification apparatus having a high voltage dry discharge filter according to the present invention.

1 is a view illustrating a configuration of an exhaust process of an exhaust gas purification reactor (Korean Patent 10-0194973) as a first embodiment of the related art. The harmful gas flowing into the gas inlet 1 is decomposed by corona discharge while passing through the positive / negative electrode plates 2 and 3. The positive electrode plate 2 and the negative electrode plate 3 are sequentially connected to a plurality of electrode plates by using an electrode connection part 5 to supply electrodes, and supplying power. The positive electrode needle 4 and the hole 6 Corona discharge occurs between). Also, positive electrode needles 4 were attached to both sides of the positive electrode plate 2 to enlarge the discharge region.

FIG. 2 is a perspective view of an exhaust gas purifying apparatus (Korean Patent 10-0194975) using a porous needle corona discharge device having improved FIG. 1 as a second conventional embodiment. The positive electrode plate 2 is positioned between the two negative electrode plates 3 so that a plurality of positive electrode needles 4 formed on both sides of the positive electrode plate 2 face the two negative electrode plates 3, respectively. It generates corona discharge and has the effect of expanding the discharge area in a narrow space. In the arrangement of the electrode plates 2 and 3, the plurality of holes 6 are arranged in a zigzag form so as not to be aligned to delay the flow of the exhaust gas, thereby providing a discharge passage, and increasing the discharge efficiency. However, it can cause an increase in back pressure.

3 is a configuration diagram of an exhaust gas aftertreatment apparatus (Korean Patent 10-0397169) by plasma discharge as a third embodiment of the prior art. A low-temperature plasma reactor 7 is provided for atomizing harmful gas components. The cathode electrode rod 8 inserted into the center of the apparatus and the anode porous cylinder 9 around it are arranged to pass the exhaust gas, thereby providing high voltage and high power. Plasma discharge occurs and exhaust gas is decomposed. In order to prevent an increase in back pressure, an air nozzle 10 for injecting high pressure air is installed at both ends of the apparatus to induce a smooth flow of exhaust gas and prevent accumulation of soot particles in the apparatus. The interior of such a discharge device was divided into three parts by inserting two separators 11, and exhaust gas was not accumulated by high pressure injection in each separator 11. Such a plasma discharge device must have a high-frequency electronic circuit and a high-voltage transformer, and the positive electrode is located outside the purifier, so that in case of breakdown, a high risk of a short circuit occurs in an automotive electric system in which the negative electrode of the battery is grounded to the vehicle body. In addition, the installation space is increased due to the installation of the high-pressure air injection device has a disadvantage of increasing the battery power consumption of the car.

Figure 4 is a block diagram of an exhaust gas purification apparatus having a high voltage dry discharge filter implemented through the present invention. The high voltage is generated using the high voltage generator 13 connected to the vehicle battery, and the harmful gases are decomposed by the corona discharge caused by the high voltage while the incoming exhaust gas passes through the discharge filter. The overall configuration of the purification device includes an inlet and outlet portion through which exhaust gas flows in, an inner housing 14 which protects the discharge filter from external shock and vibration, and an insulating material 16 for insulating the inner housing 14 and the outer housing 15. It is composed of an outer housing (15) for supporting and connecting the inlet and outlet and for connecting the high voltage circuit generated power. The inlet and outlet parts and the outer housing 15 are connected to each other by a bolt fastening part 17, and the inner housing 14 is surrounded by an insulating material 16, and is completely fixed by the inlet and outlet bolt fastening part 17 so that impact and Protect the electrode plate from vibration.

FIG. 5 is a cross-sectional view of the high voltage discharge filter of the first embodiment according to the present invention, wherein six pairs of electrode plates 3 and 4 are used in the stainless outer housing 15 using a cylindrical insulating material 16 having a high heat resistance housing shape. Heat transfer is blocked and insulated from the inner housing 14 to securely support it. The 4-8 pairs of discharge filters are fixed to the inner housing 14 by two electrode plates 8 and 18 made of a conductor and two electrode plate support bars 19 supporting the discharge filter. The discharge filter connected by the rod is inserted into the inner housing 14 and assembled in one piece to prevent sagging due to bending during shock and vibration occurrence. At this time, the portion in which the positive electrode 18 and the negative electrode plate 3 is in contact with each other by using a ceramic bushing or screw-shaped insulator 20 has an effect of preventing the electrical short and at the same time supporting the electrode plate. Similarly, the insulator 20 is also used for the contact portions of the structure of the negative electrode 8 and the positive electrode plate 2. The connection parts of the two fixed electrodes are connected to the high voltage generator 13 through the insulated outer housing 15, respectively, connected by the insulated sheathed wire 21. The two electrode plate supporting rods 19 are heat-resistant and corrosion-resistant alloy steels, and portions connected to all the discharge filters are insulated by the insulator 20, and 4-8 pairs of the discharge filters are completely fixed to the inner housing 14.

FIG. 6 is a detailed view of the high voltage discharge plate of the present invention, in order to minimize the exhaust gas flow resistance, the positive electrode plate 2 and the negative electrode plate 3 have a hexagonal arrangement and a benzene net structure having circular holes. Hazardous residual gas that has passed through the ternary catalyst spreads rapidly in one direction as a high voltage dry discharge is generated between the positive electrode needle 4 of the discharge plate and the gas passage hole 6 of the negative electrode plate 3 and decomposed into an ionic state. Will flow.

Such ionic radicals can catalyze the decomposition of the exhaust gas efficiently by catalytic reaction in the catalytically active portion of the catalyst plate. In particular, nitrogen oxide is NO ₂ is produced than NO by the discharge, the three-way catalyst is greater than the NO generation rate of NO _2. Therefore, in order to efficiently remove NO _x, a structure for simultaneously performing discharge and catalysis is required, and a microprocessing process may be performed on the surface in preparing a catalyst plate.

FIG. 7 is a cross-sectional view of a catalyst thin film high voltage discharge filter of a second embodiment according to the present invention, in which a catalyst film 22 is deposited on a position following a negative electrode plate of a high voltage discharge plate, and the catalyst plate is formed on a metal plate or an insulating substrate. First, the electrothermal metal thin film is deposited, and then the catalytic metal thin film is deposited. The preferred catalyst plate is a hot plate for depositing high-melting-point high-resistance metals such as molybdenum (Mo), tungsten (W), and nichrome alloy (Nr / Cr) on the alumina substrate to supply heat to the catalyst metal layer due to its large electrical resistance. Works. The catalyst metal is rhodium (Rd), palladium (Pd), platinum (Pt) is used, it can be fine patterned through a micro machining process. The gas passage hole is coincident with the position of the positive electrode plate and is designed with a diameter of 8-12 mm in consideration of the back pressure loss.

FIG. 8 is a detailed cross-sectional view of a portion of a catalyst plate in which a multilayer catalyst thin film is electron beam vacuum-deposited, a Ni / Cr thin film layer 25 for a hot plate for supplying heat to a catalyst metal layer on an alumina plate 23, and a Rd thin film layer serving as a catalyst metal ( 26), Pd thin film layer 27, and Pt thin film layer 28 are deposited to each 0.1-0.5 microns thick. In order to increase the contact surface area, the pattern is etched through the photolithography process after the deposition of the thin film. The size of the diameter is 120 microns and the line width is 70 microns to shape the metal pattern.

In the electron beam vacuum deposition process, the alumina substrate is initially cleaned with acetone and mounted in a vacuum container. The substrate is heated to 400 ° C. and the vessel pressure is made high vacuum at 10 ⁻⁶ Torr, and then the Ni / Cr alloy is deposited using an electron beam with a thickness of 1-5 microns so that the resistance is 5-10 × 10 ⁶ Ohm. In order to make the thickness of a board | substrate uniform, a board | substrate support plate revolves and the planetary gear train which a board | substrate rotates comprises. Thin film thickness can be controlled using a piezoelectric sensor. After depositing the heat-transfer layer thin film on the alumina substrate, the substrate is taken out and a photo process is performed. After the photoresist is applied and baked at 80 ° C., the pattern is exposed using a photomask. After the photoresist pattern is formed, the catalyst metals are further stacked in the order of Rd, Pd, and Pt in a vacuum vessel. After performing the deposition process, the catalyst metal deposited on the photoresist pattern may be removed through a lift-off process to form a patterned catalyst metal thin film layer.

In particular, Pt is used as a catalyst metal for the reduction of nitrogen oxides, and iridium (Ir) may be used instead of Pt. Tin (Sn) as well as Rd may be used to oxidize the hydrocarbon, which is the main component of particulate matter (PM). Cerium dioxide (CeO ₂ ) may be used as a cocatalyst material mixed with the alumina plate. In particular, cerium dioxide absorbs oxygen in an oxidizing atmosphere and releases oxygen in a reducing atmosphere, thereby increasing the purification efficiency and reducing the catalyst activation temperature.

8 is a block diagram of a high voltage circuit of the present invention. The circuit in the 12V car battery keeps the irregular voltage constant at 12V by means of a voltage regulator called LM317T. The current through the PNP transistor is primarily controlled by the conditions given to the controller. Given the conditions, consider the increase in exhaust gas concentrations due to engine overloads under 70 km / h, including over 500 rpm / h, when the vehicle's operating condition is considered to be steady and gear shifts. If the above conditions are met, the NPN transistor is used to purify the exhaust gas through the process of the primary coil, mutual induction, and secondary coil to boost voltage and corona discharge at high voltage. An additional direct current power source is connected to the catalyst plate, which can be controlled at a temperature of 250 ° C by a rhodium / platinum thermocouple. In addition, to prevent the risk of high voltage short-circuits, it may be possible to Automatic opening and closing control is possible.

9 is data comparing the soot concentration by attaching the discharge filter of the present invention to an actual diesel vehicle. The measuring instrument is Sangsin ENG's SSE-2002-A. The measuring vehicle is a Galloper II shortbody van (2002 model) with a displacement of 2476 CC. As can be seen from the data, the soot concentration was 1.5% before the discharge filter was installed, but 1.0% after the discharge filter was operated, and it was reduced to 0.7% when the catalyst type discharge filter was used.

As described above, in the present embodiment, in purifying automobile exhaust gas, the catalyst metal thin film is patterned by activating the gas without disturbing the flow of the exhaust gas in a pair of discharge filters using a low current dry high voltage. By decomposing efficiently through the catalyst while applying heat to the catalyst plate, it is possible to prevent the performance degradation of the engine due to back pressure loss and to manufacture a purification device that can prevent air pollution.

It is also apparent that the present invention may be modified and practiced by those skilled in the art.

Such modified embodiments should not be individually understood from the technical spirit or the prospect of the present invention, and such modified embodiments should fall within the appended claims of the present invention.

From the above description, the catalyst thin film type high voltage dry discharge type exhaust gas purifying apparatus according to the present invention has the holes of the positive electrode plate and the negative electrode plate arranged in parallel in one direction, resulting in an increase in the gas diffusion rate due to discharge, and also several pairs. Electrode plates were attached to each other to ionize the gas obtained through the discharge of the negative electrode plate. This ionic gas is immediately injected onto the surface of the catalyst plate, and the catalyst metal layer has a microcatalytic function on the patterned surface to stabilize the dissociated radicals, and a hot plate is embedded in the catalyst plate to activate the catalytic function. Has The precise purification function of the catalyst thin film discharge filter also reduces the cost of the additional filter because the dry filter does not require high power, thereby providing the safety and reliability of the exhaust gas purification system.

Claims (3)

In the post-treatment of the gas remaining after the first three-way catalyst purification of the exhaust gas of diesel vehicles, In purifying the gas through a high voltage low current dry discharge filter, In the discharge filter in which the anode needle and the cathode plate gas passage hole are aligned in one direction, A catalyst plate having a patterned shape by vacuum deposition of a multilayer thin film of a catalyst, An exhaust gas purifying apparatus for automobiles having a catalytic thin film type dry discharge filter capable of precise decomposition of high-efficiency exhaust gases by minimizing pressure loss by matching a discharge diffusion direction of a gas with a gas flow direction. In forming the catalyst plate of claim 1, a high-resistance metal is vacuum-deposited on the alumina substrate to a thickness of 1-5 microns with a heat transfer layer, On the thin film sequentially deposited a catalyst metal rhodium, palladium, platinum to a thickness of 0.1-0.5 microns, By using a photomask to fine pattern the photolithography process, Partially etched the stacked catalyst metal layer to increase the surface area, An automobile exhaust gas purifier having a catalytic thin film type high voltage dry discharge filter, characterized by activating a catalysis. In forming the heat transfer layer of the catalyst plate in claim 2, As the high melting point metal used, vacuum deposition of molybdenum, tungsten, nichrome alloy, etc., An automotive exhaust gas purification apparatus having a catalytic thin film type high voltage dry discharge filter, wherein a DC power source is additionally connected and temperature is controlled by a thermocouple.