KR101836286B1 - Catalyst oxygen purge control apparatus and the method - Google Patents

Abstract

The catalytic oxygen purge control method according to an embodiment of the present invention includes a three-way catalytic converter in which exhaust gas discharged from a combustion chamber is mixed with air and fuel, A method of controlling catalytic oxygen purge comprising the steps of: determining whether a fuel cut condition of an injector injecting fuel into the combustion chamber is satisfied; performing fuel cut-off of the injector if the fuel cutoff condition is satisfied; Determining whether the three-way catalytic converter is in an active state, measuring an oxygen storage capacity of the three-way catalytic converter if the three-way catalytic converter is in a pre-activation state, comparing the oxygen storage capacity with a cold- And adjusting the oxygen purge time based on the comparison result.

Description

[0001] CATALYST OXYGEN PURGE CONTROL APPARATUS AND THE METHOD [0002]

The present invention relates to a catalytic oxygen purge control apparatus and method, and more particularly, to an apparatus and method for shortening oxygen purge time after cold fuel-cut before catalyst activation.

Recently, as the use of automobiles has increased and traffic volume has increased, the problem of air pollution due to exhaust gas has become a serious social problem.

Accordingly, governments in each country have set emission standards for pollutants in exhaust gases such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) to regulate exhaust gas. have.

In addition, each automobile manufacturer is putting a lot of effort into effectively coping with the exhaust gas regulation which is being strengthened, and the new vehicle is produced in accordance with the exhaust gas emission standard.

In particular, in automobiles, a three-way catalyst converter carrying a precious metal is mounted on the exhaust system to meet the exhaust emission standards, thereby promoting the decomposition of hydrocarbons, the oxidation of carbon monoxide, and the reduction of nitrogen oxides.

The three-way catalyst means a catalyst which reacts with hydrocarbon compounds, carbon monoxide and nitrogen oxides (NOx) which are harmful components of exhaust gas to remove these compounds, and mainly Pt / Rh, Pd / Rh or Pt / Pd / Rh- .

These three-way catalysts function to reduce carbon monoxide and hydrocarbons and reduce nitrogen oxides in accordance with lean (rich) and rich (rich) conditions based on the air-fuel ratio of the exhaust gas.

On the other hand, in the fuel cut state, unburned air passes through the three-way catalyst, oxygen is stored in the three-way catalyst, and the purge rate of the nitrogen oxide is locally dropped by the stored oxygen when the fuel is re- And performs oxygen purge (O2 purge) function which consumes oxygen by injecting excess fuel during fuel re-injection.

In the case of the new three-way catalyst, the same oxygen purge method is applied irrespective of whether the fuel is shut off or before and after the catalyst activation in oxygen purging. The catalyst is not activated in the cold state. Therefore, when oxygen is purged on the basis of the activated catalyst, excessive hydrocarbon and carbon monoxide emissions are generated, and the exhaust gas purifying effect is deteriorated.

The present invention provides a catalytic oxygen purge control apparatus and method that can reduce the generation of exhaust gas by shortening the oxygen purge time after the cold fuel cutoff before the three-way catalyst is activated.

The catalytic oxygen purge control apparatus according to an embodiment of the present invention includes an exhaust system for exhausting exhaust gas generated from an engine, a three way catalytic converter (TWC) for supplying a catalyst to the exhaust system, And an oxygen sensor for sensing the oxygen storage capacity (OSC) of the three-way catalytic converter; and a controller for controlling the oxygen purge of the three-way catalytic converter using the catalyst temperature and the oxygen storage capacity, and an oxygen purge controller for controlling the oxygen purge time by controlling the catalytic converter according to the change control condition.

The oxygen purge time control may be performed before the activation of the three-way catalytic converter in cold conditions.

The change control condition may be at least one of an ignition timing of the engine, an idle revolutions per minute (RPM), a CAM timing, an air-fuel ratio, and an injection condition.

Meanwhile, the catalytic oxygen purge control method according to an embodiment of the present invention includes a catalytic oxygen purge control apparatus including a three-way catalytic converter in which exhaust gas discharged from a combustion chamber is mixed with air and fuel, The method according to claim 1, further comprising the steps of: determining whether a fuel cut condition of an injector injecting fuel into the combustion chamber is satisfied; and performing fuel cut-off of the injector Determining whether the three-way catalytic converter is in an activated state, measuring an oxygen storage capacity of the three-way catalytic converter when the three-way catalytic converter is in a pre-activation state, comparing the oxygen storage capacity with a cold effective oxygen storage amount And adjusting the oxygen purge time based on the comparison result.

The cold reference in the cold state can be a temperature of the three-way catalytic converter catalyst bed of less than 400 degrees and before activation of the three-way catalytic converter.

The cold reference in the cold state may be 200 seconds before the start of the engine and before the activation of the three-way catalytic converter.

The oxygen purge time can be calculated by the oxygen storage capacity of the three-way catalytic converter.

The oxygen purge time may be shorter as the oxygen storage capacity is smaller.

The oxygen storage capacity can be measured by utilizing any one of a chemisorption method, a simulated activity evaluation apparatus, an engine, and a vehicle.

According to the present invention, generation of exhaust gas can be minimized by adjusting the oxygen purge time in accordance with the cold catalyst oxygen storage characteristic.

In addition, it is possible to further improve the fuel efficiency by shortening the oxygen purge time in the cold state.

1 is a schematic block diagram of a catalytic oxygen purge control apparatus according to an embodiment of the present invention.
2 is a flowchart illustrating a method for controlling catalytic oxygen purge according to an embodiment of the present invention.
FIG. 3 is a graph showing the EM emission behavior during the cold catalytic oxygen purge according to one embodiment of the present invention.
FIG. 4 is a graph illustrating EM emission behavior during warm oxygen catalytic purge according to an embodiment of the present invention. FIG.
FIG. 5 is a graph illustrating a temperature distribution of a three-way catalytic converter in cold cathode catalytic oxygen purge according to an embodiment of the present invention. FIG.
FIG. 6 is a graph illustrating a temperature distribution of a three-way catalytic converter when performing warm oxygen catalytic oxygen purge according to an embodiment of the present invention. FIG.
7 is a graph showing the oxygen storage capacity of the catalyst according to the exhaust gas temperature according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In addition, in the various embodiments, elements having the same configuration are denoted by the same reference numerals, and only other configurations will be described in the other embodiments.

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are shown exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive. Also, to the same structure, element, or component appearing in more than one of the figures, the same reference numerals are used to denote similar features. When referring to a portion as being "on" or "on" another portion, it may be directly on the other portion or may be accompanied by another portion therebetween.

The embodiments of the present invention specifically illustrate one embodiment of the present invention. As a result, various variations of the illustration are expected. Thus, the embodiment is not limited to any particular form of the depicted area, but includes modifications of the form, for example, by manufacture.

Hereinafter, a catalyst oxygen purge control apparatus according to an embodiment of the present invention will be described with reference to FIG.

1 is a schematic block diagram of a catalytic oxygen purge control apparatus according to an embodiment of the present invention.

1, the catalytic oxygen purge control apparatus includes an exhaust system 120, a three-way catalytic converter 130, a temperature sensor 131, an oxygen sensor 132, an arithmetic unit 150, and an oxygen purge controller 140).

The exhaust system 120 exhausts the exhaust gas generated from the engine 110 and the three-way catalytic converter 130 supplies the catalyst to the exhaust system 120. The three-way catalytic converter 130 is provided with a temperature sensor 131 for sensing the catalyst temperature and is provided with an oxygen sensor 132 for sensing the oxygen storage capacity of the three way catalytic converter 130.

The engine 110 may be a continuous variable valve timing (CVVT), a double overhead camshaft (DOHC), a continuous valve timing (CVT), a gasoline direct injection (MPI) . Of course, in addition to such a gasoline engine, an embodiment of the present invention may be applied to an engine using diesel fuel and an engine using gas as fuel.

The exhaust system 120 is generally an exhaust muffler for exhausting the exhaust gas generated by the engine, but may also be constituted by a manifold, a catalytic converter, or the like.

The three-way catalytic converter 130 includes a catalyst (not shown) that performs a redox reaction with exhaust gas, a heater (not shown) that heats the catalyst, and the like.

The temperature sensor 131 senses the catalyst temperature of the three-way catalytic converter 130 and provides the sensed temperature information to the operation unit 150. The oxygen sensor 132 senses the oxygen storage capacity of the three-way catalytic converter 130 and provides the oxygen storage capacity information to the arithmetic unit 150.

The calculating unit 150 calculates a change control condition for changing the oxygen purge time of the three-way catalytic converter 130 using the catalyst temperature and the oxygen storage capacity.

The oxygen purge controller 140 controls the catalytic converter 130 according to the change control conditions to control the oxygen purge time. The oxygen purge time control may be performed prior to activation of the cold three-way catalytic converter 130 and the change control conditions may be at least one of an engine ignition timing, an idle revolutions per minute (RPM), a CAM timing, have. The most significant conditions are the ignition timing of the engine and the air-fuel ratio.

2 is a flowchart illustrating a method for controlling catalytic oxygen purge according to an embodiment of the present invention.

Referring to FIG. 2, a method of controlling catalytic oxygen purge according to an embodiment of the present invention includes: a catalytic oxygen purge control method including a three-way catalytic converter through which exhaust gas is mixed and mixed with air and fuel in a combustion chamber, First, it is determined whether the fuel cut condition of the injector injecting fuel into the combustion chamber is satisfied (S201).

Thereafter, when the fuel cut-off condition is satisfied, the fuel cut-off of the injector is performed (202).

Then, it is determined whether the three-way catalytic converter is in the activated state (S203). If the three-way catalytic converter is in the pre-activation state, the oxygen storage capacity of the three-way catalytic converter is measured (S204). The oxygen storage capacity can be measured using a chemisorption method, a simulated activity evaluation device, an engine, a vehicle, and the like.

Thereafter, the oxygen storage capacity is compared with the effective oxygen storage amount in the cold state (S205), and the oxygen purge time is adjusted based on the comparison result (S206).

In this case, the cold reference in the cold state may be before the activation of the three-way catalytic converter, when the temperature of the three-way catalytic converter catalyst bed is less than about 400 degrees. Also, it may be about 200 seconds before the start of the engine and before the activation of the three-way catalytic converter.

Further, the oxygen purge time can be calculated by the oxygen storage capacity of the three-way catalytic converter. The oxygen purge time can be made longer as the oxygen storage capacity is smaller.

FIG. 3 is a graph showing the EM emission behavior during the cold catalytic oxygen purge according to an embodiment of the present invention, and FIG. 4 is a graph showing the EM emission behavior during the warm oxygen catalytic oxygen purge according to an embodiment of the present invention. to be.

3, when the temperature of the three-way catalytic converter catalyst bed is about 400 degrees Celsius or less before the catalytic activation, about 200 seconds before the start of the engine, the oxygen fuzzy three-way catalyst converter lambda value, Hydrocarbon (THC) emissions measured at the converter outlet (WCCout) are increased, while nitrogen oxides (NOx) are emitted in small quantities.

Referring to FIG. 4, when the temperature of the three-way catalytic converter catalyst bed is about 400 degrees or more after about 200 seconds from the start of the engine, that is, after the catalytic activation, there is no hydrocarbon discharge measured at the outlet of the three- way catalytic converter. do.

As shown in FIG. 3 and FIG. 4, the oxygen purge initial hydrocarbon is continuously lengthened in a large amount before the activation of the cold catalyst, but since the hydrocarbon is not discharged after the catalytic activation in the warm state, shortening of the oxygen purge time Can be regarded as valid only in cold conditions.

FIG. 5 is a graph showing the temperature distribution of the three-way catalytic converter during the cold catalytic oxygen purge according to an embodiment of the present invention. FIG. 6 is a graph showing the temperature distribution of the three- FIG.

As shown in FIG. 5, the inlet temperature of the three-way catalytic converter at the time of the cold catalytic oxygen purge is about 220 degrees, and the bed temperature (catalyst bed temperature) of the three way catalytic converter is about 370 degrees. The catalyst bed temperature of the three-way catalytic converter can be measured using the temperature of the temperature model or by using a thermocouple. The catalyst layer is located about 1 inch from the catalyst front end.

Further, as shown in Fig. 6, the inlet temperature of the three-way catalytic converter at warm-up catalytic oxygen purge is about 330 degrees and the bed temperature of the three-way catalytic converter is about 550 degrees.

That is, the inlet and the bed temperature of the three-way catalytic converter are less than 400 degrees when performing the cold catalytic oxygen purge, and the temperature of the inlet of the three-way catalytic converter is less than 400 degrees and the bed temperature is more than 500 degrees. The three-way catalytic converter is activated at about 400 degrees.

7 is a graph showing the oxygen storage capacity of the catalyst according to the exhaust gas temperature according to an embodiment of the present invention.

As shown in FIG. 7, the three-way catalytic converter is activated when the catalyst bed temperature is about 400 degrees in the case of the gasoline vehicle of the 1.4-liter engine, and the three-way catalytic converter is not activated before about 400 degrees, The oxygen storage capacity decreases greatly. On the other hand, when the temperature is higher than about 400 degrees, the three-way catalytic converter is activated, and the change in the oxygen storage capacity with the increase in temperature is small.

The activation temperature may vary depending on the catalyst, and the measurement of the oxygen storage capacity of the catalyst can be measured using a chemisorption method, a simulated activity evaluation device, an engine, a vehicle, and the like.

Thus, according to one embodiment of the present invention, generation of exhaust gas can be minimized by controlling the oxygen purge time in accordance with the cold catalyst oxygen storage characteristic.

In addition, it is possible to further improve the fuel efficiency by shortening the oxygen purge time in the cold state.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And all changes to the scope that are deemed to be valid.

110: engine 120: exhaust system
130: Three-way catalytic converter 131: Temperature sensor
132: oxygen sensor 140: oxygen purge controller
150:

Claims (9)

delete delete delete A method for controlling the catalytic oxygen purging in a cold state of a catalytic oxygen purge control apparatus including a three-way catalytic converter in which exhaust gas is mixed with air and fuel mixed in a combustion chamber,
Determining whether a fuel cut condition of an injector injecting fuel into the combustion chamber is satisfied;
Performing fuel cut-off of the injector if the fuel cut-off condition is satisfied;
Determining whether the three-way catalytic converter is in an active state;
Measuring the oxygen storage capacity of the three-way catalytic converter if the three-way catalytic converter is in the pre-activation state;
Comparing the oxygen storage capacity with a cold storage effective oxygen amount; And
And adjusting the oxygen purge time based on the result of the comparison. 5. The method of claim 4,
Wherein the cold reference during cold is catalytic oxygen purge control wherein the temperature of the three-way catalytic converter catalyst bed is less than 400 degrees and before the three-way catalytic converter is activated. 5. The method of claim 4,
Wherein the cold reference in the cold state is 200 seconds before the start of the engine and before the three-way catalytic converter is activated. 5. The method of claim 4,
Wherein the oxygen purge time is calculated by an oxygen storage capacity of the three-way catalytic converter. 8. The method of claim 7,
Wherein the oxygen purge time is shorter as the oxygen storage capacity is smaller. 5. The method of claim 4,
Wherein the oxygen storage capacity is measured using one of a chemical adsorption method, a simulated activity evaluation device, an engine, and a vehicle.

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