KR20180029678A - Exhaust gas purification device of vehicle and control method thereof - Google Patents

Abstract

Disclosed are an exhaust gas purification apparatus of a vehicle and a control method thereof. The exhaust gas purification apparatus of a vehicle comprises: a hydrocarbon trap catalyst installed on an exhaust gas pipe in which exhaust gas flows, for absorbing and separating hydrocarbon in the exhaust gas; a heating device-embedded EHC TWC/NSR catalyst installed on the exhaust gas pipe in the downstream than the hydrocarbon trap catalyst in a flow path of the exhaust gas for absorbing nitrogen oxide; and an air injector installed on the exhaust gas pipe in the upstream than the hydrocarbon trap catalyst in a flow path of the exhaust gas for spraying the air to the inside of the exhaust gas pipe. The exhaust gas purification apparatus of a vehicle can effectively reduce harmful components of the exhaust gas during the cold repairing of a vehicle.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an exhaust gas purifying apparatus,

More particularly, the present invention relates to an exhaust purification apparatus for a vehicle and a control method thereof, and more particularly, to an exhaust purification apparatus and a control method thereof for an EHC (Electrically Controlled) Heated Catalyst By purifying nitrogen oxides (NOx) adsorbed on EHC TWC / NSR using reducing gas generated by oxidation of hydrocarbons in TWC (Three Way Catalyst) / NSR (NOx Storage Reduction) catalyst, And more particularly, to an exhaust purification apparatus for a vehicle and a control method therefor.

Generally, a vehicle uses an engine to burn fuel, thereby generating power necessary for driving the vehicle. Combustion gas is inevitably generated in the combustion process of the fuel using the engine, and such combustion gas (exhaust gas) is released to the atmosphere through the exhaust device.

2. Description of the Related Art In recent years, as the interest in the global environment has increased, many researches and developments are under way to reduce harmful substances contained in exhaust gas emitted from vehicles.

Particularly, exhaust gas discharged from a diesel engine or a gasoline engine used in a vehicle is making a lot of efforts to reduce particulate matter and nitrogen oxides (NOx), which are particularly harmful to the global environment.

In order to reduce harmful substances contained in the exhaust gas such as particulate matter and nitrogen oxides, a filter and a catalyst are usually used. As an example thereof, a Three Way Catalyst (TWC) (HC) and carbon monoxide (CO), nitrogen oxides, and the like, which are discharged from the engine, are substantially completely cleaned. However, in the cold starting period of the vehicle, the purification performance is deteriorated and a large amount of harmful substances There is a disadvantage that it is discharged.

A method of increasing the warming-up speed of the catalytic converter by mounting a catalytic converter at a position closer to the engine in order to reduce the harmful substances of the exhaust gas in the cold start period of the vehicle has been used. However, There were disadvantages.

Recently, a system combining a hydrocarbon (HC) trap catalyst and an NSR (NOx Storage Reduction) catalyst has been attracting attention, and a hydrocarbon (HC) trap catalyst has been developed at the time when the warm- (Zeolite) is used to remove hydrocarbons from hydrocarbons and to adsorb hydrocarbons to a temperature range of 150 to 250 ° C.

The NSR has a characteristic of storing nitrogen oxides under the lean operation condition of the engine, and is a catalyst for desorbing nitrogen oxides at a lambda (air-fuel ratio) = 1 and purifying them with a gasifier.

It is preferable to mount the hydrocarbon (HC) trap catalyst and the NSR (NOx Storage Reduction) catalyst on the underfloor (the vehicle body bottom panel) in consideration of the durability of the material and the use temperature. However, in order for the NSR to operate normally, a temperature of 200 DEG C or more is required. However, as described above, the NSR is not equipped with an underfloor and can not be warmed up early, .

Accordingly, it has been necessary to reduce the harmful substances of the exhaust gas by allowing the catalyst system combining the hydrocarbon (HC) trap catalyst and the NSR (NOx Storage Reduction) catalyst to perform normally in the cold start period of the vehicle.

In an embodiment of the present invention, air is injected at the time when hydrocarbon starts to be desorbed from the hydrocarbon trap catalyst at the same time as the vehicle is cold, and EHC TWC / NSR catalyst is oxidized by using a reducing gas generated by oxidizing hydrocarbons in the EHC TWC / By purifying the adsorbed nitrogen oxides, it is possible to prevent leakage of the ammonia gas from the ammonia gas generated in the aqueous solution storage tank of the exhaust gas purifying device of the vehicle that effectively reduces exhaust harmful components at the same time as the vehicle is cold, An exhaust purification apparatus for a vehicle and a control method thereof for preventing environmental pollution.

An exhaust purification apparatus for a vehicle according to an embodiment of the present invention includes: a hydrocarbon trap catalyst installed in an exhaust pipe through which exhaust gas flows to adsorb and desorb hydrocarbons in the exhaust gas; An EHC TWC / NSR catalyst installed in the exhaust pipe downstream of the hydrocarbon trap catalyst in a flow path of the exhaust gas to adsorb nitrogen oxides and incorporating a heating device; And an air injector installed in the exhaust pipe upstream of the hydrocarbon trap catalyst in the flow path of the exhaust gas and injecting air into the exhaust pipe.

And an ECU for selectively supplying power to the EHC TWC / NSR catalyst by applying a control signal for air injection to the air injector according to the starting state of the engine.

The ECU senses the cooling water temperature when the driver's will is determined, and when the cooling water temperature is below the predetermined temperature, the EHC TWC / NSR catalyst can be supplied with power.

The predetermined temperature may be 80 DEG C or less.

The driver's will determination may be made by whether the brake pedal is operated, whether the ignition key is inserted, whether the seat belt is worn, or a combination thereof.

The temperature of the EHC TWC / NSR catalyst may be controlled to be raised to 200 ° C or lower by the power supply of the ECU.

The control signal application of the air injector by the ECU may be performed after the power supply to the EHC TWC / NSR catalyst is cut off.

According to another aspect of the present invention, there is provided a method of controlling a vehicle re-purifier, including: determining a driver's intention to drive; A cooling water temperature determination step of determining a cooling water temperature of the engine and determining whether the cooling water temperature is lower than a predetermined temperature; Supplying power to the EHC TWC / NSR catalyst when the cooling water temperature determined in the cooling water temperature determination step is lower than a predetermined temperature; Sensing the temperature of the EHC TWC / NSR catalyst; Shutting off the power supply to the EHC TWC / NSR catalyst when the temperature of the EHC TWC / NSR catalyst is above a predetermined temperature; And injecting air into the exhaust pipe upstream of the hydrocarbon trap catalyst.

According to the exhaust purification apparatus and control method for a vehicle according to the embodiment of the present invention, the TWC / NSR catalyst built in the EHC TWC / NSR is activated in a short period of time using the EHC TWC / NSR catalyst, After trapping hydrocarbons and nitrogen oxides using a trap catalyst and activated TWC / SCR, air is sprayed at the point where the hydrocarbon is desorbed due to the temperature rise of the hydrocarbon trap, resulting in oxidation of hydrocarbons on the TWC / By purifying the adsorbed nitrogen oxide using the reducing gas, the harmful components of the exhaust gas can be effectively reduced at the same time as the vehicle is cold.

1 is a configuration diagram of an exhaust purification apparatus for a vehicle according to an embodiment of the present invention.
2 is a flowchart of a control method of an exhaust purification apparatus for a vehicle according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1, an exhaust purification apparatus for a vehicle according to an embodiment of the present invention may be installed in an exhaust pipe 10 for guiding the exhaust gas generated in a combustion process of a fuel in an engine of a vehicle to the outside of the engine .

A WCC (WORM-UP CATALYST CONVERTER) 20 is installed upstream of the exhaust pipe 10 through which the exhaust gas discharged from the engine flows, so that the exhaust gas can be primarily purified.

A hydrocarbon (HC) trap catalyst 30 may be installed downstream of the WCC 20 on the exhaust gas flow path of the exhaust pipe 10.

The EHC TWC / NSR catalyst 40 may be installed downstream of the hydrocarbon trap catalyst 30 on the exhaust gas flow path of the exhaust pipe 10.

EHC (Electrically Heated Catalyst) TWC (Three Way Catalyst) / NSR (NOx Storage Reduction) catalyst 40 is a catalyst in which an electric heating device is embedded in a catalyst can. TWC and NSR are built in a catalyst can, When power is supplied, heat is generated and TWC and NSR are heated.

An air injector 50 may be installed upstream of the hydrocarbon trap catalyst 30 on the exhaust gas flow path of the exhaust pipe 10 to inject air into the exhaust pipe 10.

An engine control unit (ECU) may be connected to the air injector 50 as a control device of the air injector 50 to control the injection timing of the air injector 50.

The ECU may also be connected to the EHC TWC / NSR catalyst 40 to selectively supply power for heating the EHC TWC / NSR catalyst 40.

In addition, the ECU can be connected to various sensors 60, for example, a brake pedal operation detection sensor, a key insertion detection sensor, or a seat belt wear detection sensor to determine the driving will of the driver, And can be connected to a coolant temperature sensor for heat.

2 showing the control procedure of the exhaust purification apparatus for a vehicle according to the embodiment of the present invention constructed as above, a driver depresses a brake pedal, inserts a starter key, In case of wearing, the ECU senses this through the sensor 60 and senses the driving intention of the driver.

When the ECU senses the driving intention of the driver as described above, the ECU senses through the sensor 60 whether or not the cooling water temperature of the engine is 80 DEG C or less.

When the engine coolant temperature is 80 캜 or less at the time of starting the vehicle, it means that the vehicle is cold-started when the vehicle is not operated for a long time or when the vehicle is operated during the winter season.

When the vehicle is cold-started, the exhaust purifying device is not sufficiently warmed up, so that the exhaust purifying device can not be operated smoothly.

Accordingly, in the present invention, the exhaust purifying device is suitably preheated so that the exhaust purifying device can be smoothly operated.

That is, the ECU supplies power to the EHC TWC / NSR catalyst 40 to heat the TWC / NSR catalyst incorporated in the EHC TWC / NSR catalyst 40, preferably the EHC TWC / NSR catalyst 40 The ECU continues to supply power to the EHC TWC / NSR catalyst 40 to heat the EHC TWC / NSR catalyst 40 until the temperature reaches about 200 ° C.

After raising the temperature of the EHC TWC / NSR catalyst 40 to about 200 ° C, the ECU stops supplying power to the EHC TWC / NSR catalyst 40 and thereafter the EHC TWC / NSR catalyst 40 ) Is heated so that the heating energy of the EHC TWC / NSR catalyst 40 is minimized as much as possible.

After storing the hydrocarbon (HC) and the nitrogen oxide (NOx) generated in the cold start section within about 20 seconds after the engine is started, the hydrocarbon trap catalyst 30 and the EHC TWC / NSR catalyst 40, The temperature of the hydrocarbon trap catalyst 30 rises to approximately 200 to 250 ° C after about 20 seconds after the start of the engine. At this point, the adsorbed hydrocarbon starts desorbing, and the ECU controls the air injector 50 So that air is injected from the air injector 50.

Then, hydrocarbons starting to be desorbed in the EHC TWC / NSR catalyst 40 are oxidized by air, and nitrogen oxide (NOx) adsorbed in the EHC TWC / NSR catalyst 40 is effectively It is purified.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Various modifications and variations are possible within the scope of the appended claims.

10: Exhaust pipe
20: WCC
30: hydrocarbon trap catalyst
40: EHC TWC / NSR
50: Air injector
60: Sensor

Claims (11)

A hydrocarbon trap catalyst installed on an exhaust pipe through which exhaust gas flows to adsorb and desorb hydrocarbons in the exhaust gas;
An EHC TWC / NSR catalyst installed in the exhaust pipe downstream of the hydrocarbon trap catalyst in a flow path of the exhaust gas to adsorb nitrogen oxides and incorporating a heating device; And
An air injector installed in the exhaust pipe upstream of the hydrocarbon trap catalyst in a flow path of the exhaust gas to inject air into the exhaust pipe;
And an exhaust gas purifying device for purifying exhaust gas. The method according to claim 1,
Further comprising an ECU for applying a control signal for air injection to the air injector according to a starting state of the engine and selectively supplying power to the EHC TWC / NSR catalyst. 3. The method of claim 2,
Wherein the EHC TWC / NSR catalyst is adapted to supply power to the EHC TWC / NSR catalyst when the cooling water temperature is below a predetermined temperature, . 3. The method of claim 2,
Wherein the predetermined temperature is 80 占 폚 or less. 3. The method of claim 2,
Wherein the driver's will determination is made by whether the brake pedal is operated, whether the ignition key is inserted, whether the seat belt is worn, or a combination thereof. The method of claim 3,
And the temperature of the EHC TWC / NSR catalyst is controlled to be raised to 200 ° C or lower by power supply to the ECU. 3. The method of claim 2,
Wherein the control signal application of the air injector by the ECU is performed after power supply to the EHC TWC / NSR catalyst is cut off. Determining a driving intention of the driver;
A cooling water temperature determination step of determining a cooling water temperature of the engine and determining whether the cooling water temperature is lower than a predetermined temperature;
Supplying power to the EHC TWC / NSR catalyst when the cooling water temperature determined in the cooling water temperature determination step is lower than a predetermined temperature;
Sensing the temperature of the EHC TWC / NSR catalyst;
Shutting off the power supply to the EHC TWC / NSR catalyst when the temperature of the EHC TWC / NSR catalyst is above a predetermined temperature;
Injecting air into an exhaust pipe upstream of the hydrocarbon trap catalyst;
And a control unit for controlling the exhaust gas purifying apparatus. 9. The method of claim 8,
Wherein the driver's will determination is made by whether or not the brake pedal is operated, whether the ignition key is inserted, whether the seat belt is worn, or a combination thereof. 9. The method of claim 8,
Wherein the predetermined temperature of the cooling water temperature is 80 占 폚 or less. 9. The method of claim 8,
Wherein the predetermined temperature of the EHC TWC / NSR catalyst is 200 占 폚 or higher.

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