KR20000015196U - Canister Exhaust Treatment System - Google Patents

Abstract

The present invention relates to an exhaust aftertreatment apparatus for removing harmful components of exhaust gas generated in a lean-burn automobile, and more particularly, by using a hydrocarbon, a boil-off gas stored in a canister, as a reducing agent for nitrogen oxides. The present invention relates to a canister exhaust aftertreatment device that effectively reduces nitrogen oxides (NOx), which are mainly emitted from automobiles.

According to the canister exhaust aftertreatment device of the present invention, when operating under lean combustion conditions, the nitrogen oxide reducing agent stored in the canister is supplied to the front of the catalytic converter so that the excess oxygen is consumed by the redox reaction so that the catalyst is occupied by oxygen. It is possible to prevent the phenomena, and to increase the efficiency of purifying nitrogen oxides by using the hydrocarbon which is the evaporation gas of the fuel tank as a reducing agent participating in the nitrogen oxide reduction reaction, and also using the evaporated gas stored in the conventional canister. In addition, there is an effect that an apparatus for supplying a nitrogen oxide reducing agent is unnecessary.

Description

Canister Exhaust Treatment System

The present invention relates to an exhaust aftertreatment apparatus for removing harmful components of exhaust gas generated in a lean-burn automobile, and more particularly, by using a hydrocarbon, a boil-off gas stored in a canister, as a reducing agent for nitrogen oxides. The present invention relates to a canister exhaust aftertreatment device that effectively reduces nitrogen oxides (NOx), which are mainly emitted from automobiles.

Efforts are being made globally to reduce CO2 emissions from automobiles in order to improve fuel efficiency and prevent global warming, especially in advanced countries. burn) A car is under development.

A lean burn car is driven in a very lean state with an air / fuel ratio (A / F) of 18 or more, unlike a conventional gasoline car operating at a theoretical performance ratio (A / F) of about 14.7. For this reason, the exhaust gas of the lean burn car includes a lot of nitrogen oxides (NOx), which is the biggest problem in the development of the lean burn car.

In other words, since the three-way catalyst device conventionally used as an exhaust post-treatment device for a gasoline vehicle cannot effectively remove nitrogen oxides (NOx) in the lean burn area, the development of a new concept of a lean-burn car exhaust post-treatment system is difficult. It is becoming a major concern around the world.

FIG. 1 is a schematic view showing a conventional lean burn automobile exhaust post-treatment apparatus, a catalyst having a catalyst 5 for purifying mainly nitrogen oxides (NOx) among exhaust gases discharged from an exhaust manifold (1). The converter 2 is provided in the exhaust pipe 4 between the exhaust manifold 1 and the muffler 3.

The catalytic converter 2 is composed of a catalyst 5 installed by a mat in a housing, and the catalyst 5 is a catalyst for purifying nitrogen oxides excellent in purifying nitrogen oxides.

In addition, the catalyst 5 is coated with a wash coat on a carrier of 200 to 500 cell / inch ² made of ceramic or metal, and then platinum (Pt), palladium (Pd), and rhodium (Rh) Or it is to carry a ruthenium-based metal. The washcoat of the catalyst 5 is composed of a support such as alumina (Al ₂ O ₃ ), and an oxide modifier of cerium (Ce), zirconium (Zr), barium (Ba), and lanthanum (La) series. have.

According to the above system, regardless of the combustion conditions of the lean burn car, it acts as a reducing agent capable of reducing nitrogen oxides (NOx), such as hydrocarbons (HC) and carbon monoxide (CO) contained in the exhaust gas emitted from the engine. The components reduce nitrogen oxides in the catalyst 5 of the catalytic converter 2.

This effect is that when the car is operated under the condition of rich or theoretical fuel consumption, the exhaust gas is rich in hydrocarbon (HC) and carbon monoxide (CO), so the reduction of nitrogen oxides (NOx) occurs actively, thereby increasing the purification efficiency. Reduction of the nitrogen oxides is not disturbed by oxygen by appropriately consuming oxygen contained in the exhaust gas by oxidizing the reducing agent.

However, the exhaust gas of lean burn cars contains more oxygen than general gasoline cars, and when such oxygen is adsorbed on the catalyst surface competitively with nitrogen oxide when it operates in a dedicated catalyst to purify nitrogen oxide, it is nitrogen oxide. This takes up the adsorption point to be adsorbed and purified. As a result, the adsorption point to which nitrogen oxides should be adsorbed is reduced, and the nitrogen oxides not adsorbed to the catalyst are released into the atmosphere without being purified. This phenomenon is exacerbated as the vehicle is operated under lean burn conditions and the catalyst operation time elapses.

Therefore, the present invention has been made to solve the above problems, and the object of the present invention is to effectively reduce nitrogen oxides, which are harmful components of exhaust gases, under lean burn conditions of lean burn cars as well as rich and theoretical performance ratio conditions. It is to provide a processing device.

1 is a block diagram showing an exhaust post-treatment apparatus of a conventional lean burned vehicle;

Figure 2 is a block diagram showing a canister exhaust post-treatment apparatus of an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1: Exhaust manifold 2: Catalyst converter

3: muffler 4: exhaust pipe

5: catalyst 6: canister

7: Adsorbent 8: Flow control device

9: Pressure sensor 10, 12, 15: 1st, 2nd, 3rd connector

11,13,14,16: 1st, 2nd, 3rd, 4th solenoid control valve

17: purge pipe 18: electronic control device

In order to achieve the above object, the canister exhaust aftertreatment device of the present invention adsorbs a catalytic converter installed in an exhaust pipe to purify exhaust gas discharged from an exhaust manifold by a catalyst, and hydrocarbons, which are evaporated gases of an automobile fuel tank. And a canister which is stored and supplied as a reducing agent to the exhaust gas flowing into the catalytic converter, and the remainder is introduced into the intake manifold for combustion in the engine, and in front of the catalytic converter so that the hydrocarbon can flow from the canister to the catalytic converter. A first connection pipe connected between one side of the exhaust pipe and the canister, a purge pipe connected to one side of the canister to communicate with the atmosphere, a second connection pipe connected between the intake manifold and the canister, and a first connection pipe connected between the fuel tank and the canister. A third connection pipe, a first electronic control valve installed at the first connection pipe, and the second connection And a second electronic control valve installed in the control valve, a third electronic control valve installed in the third connecting pipe, and an electronic control device for interlocking and opening the electronic control valves in accordance with lean burning conditions or rich and theoretical performance ratio conditions. It is characterized by being.

In particular, the pressure sensor and flow rate regulator for supplying nitrogen oxide reducing agent supplied from the canister is further installed in the first connection pipe, and the fourth electronic control valve is further installed in the purge pipe.

In addition, the canister is characterized by having an adsorbent consisting of at least one selected from activated carbon, zeolite or alumina capable of adsorbing and storing hydrocarbons.

Hereinafter, a canister exhaust post-treatment apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a schematic diagram showing a canister exhaust post-treatment apparatus according to an embodiment of the present invention.

As shown in FIG. 2, the canister exhaust aftertreatment apparatus according to the embodiment of the present invention is installed in the exhaust pipe 4 to purify the exhaust gas discharged from the exhaust manifold 1 by the catalyst 5. After adsorbing and storing the catalytic converter 2 and the hydrocarbon which is the evaporated gas of the automobile fuel tank, the catalyst is supplied as a reducing agent to the exhaust gas flowing into the catalytic converter 2 and the rest is introduced into the intake manifold so as to be burned by the engine. A first connection between the canister 6 and one side of the exhaust pipe 4 in front of the catalytic converter 2 and the canister 6 so that the hydrocarbons can flow from the canister 6 to the catalytic converter 2. The tube 10, the purge tube 17 connected to one side of the canister 6 to communicate with the atmosphere, the second connecting tube 12 connected between the intake manifold and the canister 6, the fuel tank and the canister (3) a third connecting pipe 15 connected between the above, A first electronic control valve 11 installed on the first connecting pipe 10, a second electronic control valve 13 installed on the second connecting pipe 12, and a third installed on the third connecting pipe 15. A three solenoid control valve 14 and an electronic control device 18 for opening and closing the solenoid control valves 11, 13 and 14 in accordance with lean burning conditions or rich and theoretical performance ratio conditions are provided.

In particular, the pressure sensor 9 and the flow regulator 8 for nitrogen oxide reducing agent supply control supplied from the canister 6 are installed in the first connection pipe 10, and the fourth purge pipe 17 is provided. An electronic control valve 16 is provided.

In addition, the canister 6 includes an adsorbent 7 made of at least one selected from activated carbon, zeolite or alumina capable of adsorbing and storing hydrocarbons.

The electronic controller 5 stores hydrocarbons stored in the canister 6 by opening the first and fourth valves 11 and 16 and closing the second and third valves 13 and 14 in the lean burn condition. Is supplied to the catalytic converter (2), and in the case of rich or theoretical performance ratio conditions, the second and third valves (13, 14) are opened and the first and fourth valves (11, 16) are closed to evaporate the fuel tank. The hydrocarbon, which is a gas, is introduced into the canister 6 to control adsorption and storage.

In addition, the electronic control device 5 is supplied by the pressure sensor 9 installed in the first connecting pipe 21 when hydrocarbon is supplied from the canister 6 to the catalytic converter 2 in the lean burn condition. The inflow flow rate is adjusted by the flow controller 8 so that the set flow rate is introduced according to the pressure of the flow rate.

Next, the operation of the canister exhaust aftertreatment apparatus according to the embodiment of the present invention configured as described above will be described.

First, when the lean burn car is operated in the rich or theoretical fuel consumption range, the first and fourth electromagnetic control valves 11 and 16 are blocked by the electronic control device 18, and the second and third electronic control valves 13 are closed. 14 is open. Accordingly, the hydrocarbon, which is the evaporated gas of the fuel tank, enters the canister 6 through the third connecting pipe 15, is adsorbed and stored in the canister 6 by the adsorbent 7, and the rest of the second connecting pipe 15. Through 12 it is introduced into the intake manifold again.

When enough hydrocarbon is stored in the canister 6, the second and third electronic control valves 13 and 14 which were opened are closed.

Next, when the lean burn car is operated under lean combustion conditions, the first and fourth electromagnetic control valves 11 and 16 are opened by the electronic controller 18, and the second and third electromagnetic control valves 13, 14) is closed. Therefore, the outside air flows through the purge pipe 17, passes through the adsorbent 7 embedded in the canister 6, and leaves the hydrocarbon stored therein, thereby allowing the catalytic converter 2 to pass through the first connecting pipe 10. Spread forward. This process is possible because the flow rate of the exhaust gas flowing into the catalytic converter 2 is very fast because the first connecting pipe 10 and the canister 6 are maintained at a lower than atmospheric pressure.

When the negative pressure is excessively large, the amount of hydrocarbon introduced through the first connecting pipe 10 increases and the hydrocarbon, which is a nitrogen oxide reducing agent, is excessively supplied to the catalytic converter 2, so that the electronic controller 5 The controller controls the flow regulator 8 to sense the pressure with the pressure sensor 9 installed in the first connection pipe 10 to adjust the flow rate to the set value.

The hydrocarbon supplied as a catalyst of the catalytic converter acts as a reducing agent of nitrogen oxides (NOx) to reduce to harmless nitrogen (N ₂ ) and oxygen (O ₂ ), and itself is harmless hydrogen (H ₂ ), water vapor (H ₂ O). Or oxidized to carbon dioxide (CO ₂ ) and released into the atmosphere through mufflers and exhaust pipes.

The canister exhaust aftertreatment device of the present invention can be used in conventional gasoline cars, alternative fuel cars, natural gas, alcohol, hydrogen cars, diesel cars, and the like.

As described above, according to the canister exhaust post-treatment apparatus of the present invention, when operating under lean combustion conditions, the nitrogen oxide reducing agent stored in the canister is supplied to the front of the catalytic converter to adequately consume excess oxygen by the redox reaction, The phenomenon occupied by oxygen can be prevented, and the hydrocarbon which is the evaporation gas of the fuel tank acts as a reducing agent that directly participates in the nitrogen oxide reduction reaction, so that the purification efficiency of the nitrogen oxide can be increased and the evaporated gas stored in the conventional canister. Because of the use of the device there is an effect that a device for supplying a nitrogen oxide reducing agent is further unnecessary.

Claims (6)

After adsorbing and storing the catalytic converter 2 installed in the exhaust pipe 4 so as to purify the exhaust gas discharged from the exhaust manifold 1 by the catalyst 5, and the hydrocarbon which is the evaporation gas of the automobile fuel tank, A canister (6) for supplying the exhaust gas flowing into the catalytic converter (2) as a reducing agent and the remaining inlet to the intake manifold for combustion in the engine, and the hydrocarbon flows from the canister (6) to the catalytic converter (2). A first connecting pipe 10 connected between one side of the exhaust pipe 4 in front of the catalytic converter 2 and the canister 6, and a purge pipe connected to one side of the canister 6 so as to communicate with the atmosphere. 17), a second connecting pipe 12 connected between the intake manifold and the canister 6, a third connecting pipe 15 connected between the fuel tank and the canister 6, and the first connecting pipe 10 The first electric control valve 11 installed in the) and the second electric field installed in the second connecting pipe (12) The control valve 13, the third electronic control valve 14 installed in the third connecting pipe 15, and the electronic control valves (11, 13, 14) according to the lean burning conditions or rich and theoretical performance ratio conditions Canister exhaust after-treatment device, characterized in that it comprises an electronic control unit 18 for opening and closing in conjunction with each other. The canister after exhausting the canister according to claim 1, further comprising a pressure sensor (9) and a flow regulator (8) for supplying nitrogen oxide reducing agent supplied from the canister (6) in the first connection pipe (10). Processing unit. The canister exhaust aftertreatment device according to claim 2, wherein a fourth electromagnetic control valve (16) is further provided in the purge pipe (17). 3. The canister after-treatment apparatus according to claim 2, wherein the canister (6) includes an adsorbent (7) made of at least one selected from activated carbon, zeolite, and alumina capable of adsorbing and storing hydrocarbons. 4. The canister (6) according to claim 3, wherein the electronic controller (5) opens the first and fourth valves (11, 16) and closes the second and third valves (13, 14) under lean burn conditions. ) Is supplied to the catalytic converter (2), and in the case of rich or theoretical performance ratio conditions, the second and third valves 13 and 14 are opened and the first and fourth valves 11 and 16 are opened. And a canister exhaust post-treatment device configured to be closed so that hydrocarbon, which is the evaporated gas of the fuel tank, is introduced into the canister (6) to be adsorbed and stored. 6. The electronic control device (5) according to any one of claims 2 to 5, wherein the electronic control device (5) has a first connecting pipe (21) when hydrocarbons are supplied from the canister (6) to the catalytic converter (2) under lean combustion conditions. Canister exhaust post-treatment apparatus, characterized in that for adjusting the inflow flow rate to the flow rate regulator (8) so that the set flow rate is introduced in accordance with the pressure of the supply flow rate detected by the pressure sensor (9) installed in the.