KR101448735B1 - A catalyst diagnosis system of vehicle and - Google Patents

Abstract

The present invention relates to a catalyst diagnosis apparatus for a vehicle, and more particularly, to a catalyst diagnosis method of a vehicle which diagnoses abnormal deactivation of oxygen storage capacity (OSC) of a catalyst caused by pollutants such as a poor fuel component, to be.

The present invention is characterized by analyzing information of the first and second oxygen sensors under the idle condition, detecting the OSC (oxygen absorption and desorption ability) value of the catalyst for each cycle, and comparing the OSC Calculating the rate of change of the OSC (oxygen absorption / desorption capability) value based on the first detected OSC (oxygen absorption / desorption capability) value when the value of the OSC (absorption / release ability) value exceeds the failure determination threshold value, A process in which the ceria, which is a catalyst constituting material, is judged to be contaminated by the fuel component and the pollution counter is increased; if the cumulative value of the pollution counter for the ceria exceeds the set number, contamination of the ceria by the poor fuel component occurs State or the emission of the catalyst is determined to maintain the normal state, thereby avoiding a malfunction determination for the catalyst.

Catalyst, ceria, fuel pollution, OSC,

Description

[0001] CATALYST DIAGNOSIS SYSTEM OF VEHICLE AND [0002]

The present invention relates to a catalyst diagnosis apparatus for a vehicle, and more particularly, to a catalyst diagnosis apparatus for a vehicle which diagnoses that an oxygen storage capacity (OSC) of a catalyst due to a pollutant such as a poor fuel component is abnormally inactivated, And more particularly, to a catalyst diagnostic apparatus and method for a vehicle.

The vehicle is equipped with a catalyst that stabilizes the emission (E / M) by purifying various harmful substances such as HC, CO and NOx contained in the exhaust gas. The catalyst is a mixture of ceria (CeO2) and zirconia (ZrO2) .

As shown in FIG. 4, in the conventional catalyst diagnosis method, the ceria, which is a constituent material of the catalyst, absorbs oxygen at a condition where the air-fuel ratio is lean, (OSC) by estimating the catalytic function as the oxygen absorption capacity (OSC) by using the coherent property of the ceria that emits oxygen.

That is, when the air-fuel ratio is changed from lean to rich in the idle operation, the first oxygen sensor installed on the upstream side of the catalyst and the second oxygen sensor installed on the downstream side of the catalyst depend on the deterioration degree of ceria, And the time delay is changed.

The ceria, which is a constituent of the catalyst, has a shorter time delay due to deterioration of the oxygen absorption / desorption ability as the deterioration progresses, and the principle of lengthening in the normal case is used.

Therefore, when the time delay of the oxygen absorption / desorption capability (OSC) detected through the first oxygen sensor and the second oxygen sensor is detected to be equal to or shorter than the set reference time, it is determined that an abnormality has occurred in the catalytic function.

In general, the relationship between the oxygen absorption capacity (OSC) of the ceria, which is a constituent of the catalyst, and HC is maintained without any problem. That is, as the deterioration of the catalyst progresses, the purification capability of the HC is lowered and the oxygen absorptive capacity (OSC) is also lowered.

However, when the catalyst is deteriorated by sulfur, phosphorus, silicon, or the like, which is called impurities in the fuel or the engine oil additive in the running on actual roads, a phenomenon occurs in the catalyst.

Normally, the content of additives for fuel or engine oil is very high in each country, and when the chemical deterioration of the ceria constituting the catalyst is caused by the impurities, only the oxygen absorption capacity (OSC) is abnormally deactivated And thus the failure of the catalyst is judged, thereby causing an error of the OBD system.

For example, in the case of a vehicle mass-produced in China, the cause of the removal of the catalyst with the warning light on the road was investigated. As a result, the actual degree of HC deterioration was small, but only the oxygen absorption capacity (OSC) was abnormally deactivated , It was found that the inside wall of the exhaust manifold and the interior of the carrier had dark white or yellow color which is supposed to be contaminants such as sulfur, silicon, and phosphorus.

In the ceria material deactivated due to such pollutants, the oxygen absorption capacity (OSC) varies greatly according to the temperature of the catalyst. When the catalyst temperature is low, the oxygen absorption capacity (OSC) The time of the oxygen absorption and desorption capability (OSC) is very long.

That is, it can be seen that the phase change occurs in the contaminated ceria mixture according to the temperature condition of the catalyst.

5 is a graph comparing deviations in the oxygen adsorption / desorption ability between the high catalyst and the new catalyst according to the catalyst temperature.

As can be seen from the figure, in the case of a high-quality catalyst, the ability to absorb and discharge oxygen rapidly changes depending on the temperature of the catalyst, while the normal catalyst provides oxygen absorption and desorption ability irrespective of the temperature of the catalyst Able to know.

Current vehicles do not have the logic to diagnose abnormal deactivation of the catalyst due to the pollution of the fuel, thus causing errors in the OBD system.

In addition, in order to increase the counterforce against the abnormal deactivation of the catalyst in response to the coarse fuel, there is a problem that it leads to the upgrade of the catalyst specification such as the increase of the loading amount of the noble metal and the increase of the ceria.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and its object is to provide a fuel cell system capable of detecting a phenomenon in which oxygen adsorption / desorption ability of a ceria catalyst is abnormally inactivated by pollutants such as a poor fuel component, .

That is, catalyst deterioration or non-degradation is separated and separated by using an abnormal phenomenon of oxygen absorption / desorption ability different from normal deterioration catalyst, and only functional failure catalyst having a problem of emission is judged as failure.

In order to achieve the above object, a catalyst diagnosis apparatus for a vehicle according to a feature of the present invention comprises: a catalyst for purifying an exhaust gas by an oxidizing and reducing action; First and second oxygen sensors provided upstream and downstream of the catalyst, respectively, for detecting the oxygen concentration according to the lean / rich transition of the air-fuel ratio; The oxygen absorption capacity of the catalyst is detected under the idle condition and is compared with the threshold value. If the value of the first detected oxygen absorption / desorption ability exceeds the threshold value by calculating the rate of change of the number of times exceeding the threshold value, And a controller for avoiding the catalyst failure diagnosis when the contamination judgment counter exceeds the set number of times and adjusting the threshold value of the failure judgment upward.

According to another aspect of the present invention, there is provided a method for diagnosing a catalyst for a vehicle, the method comprising: analyzing information of the first and second oxygen sensors under idling conditions to detect an OSC (oxygen absorption / desorption capability) Comparing with a threshold value; Calculating a rate of change of the OSC (oxygen absorptive emission capability) value based on the first detected OSC (oxygen absorptive capacity) value when the OSC (oxygen absorptive capacity) value of the catalyst exceeds a failure determination threshold value; If the calculated rate of change exceeds a predetermined reference value, determining that the ceria, which is a catalyst component, is contaminated by the fuel component and increasing the pollution counter; If the cumulative value of the contamination counter for the ceria exceeds the set number, it is determined that the ceria is contaminated by the poor fuel component, but the emission of the catalyst is maintained to be normal, thereby avoiding the malfunction determination for the catalyst do.

According to the above-described configuration, the present invention clearly discriminates whether or not the inactivation of the oxygen adsorption / desorption ability by the poisoning of the ceria constituting the catalyst in the vehicle is unacceptable, and only the deterioration of the catalytic function exceeding the actual E / Diagnosis, it is expected that the cost reduction effect and the stability and reliability of the OBD system can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

The present invention may be embodied in many different forms and is not therefore limited to the embodiments described herein. For the sake of clarity, the present invention is not described herein.

1 is a diagram showing a schematic configuration of a catalyst diagnosis apparatus for a vehicle according to an embodiment of the present invention.

The present invention may be applied to an engine 100 that is a power source of a vehicle and an air amount sensor 110, a catalyst 200, a first oxygen sensor 210, a second oxygen sensor 220, a temperature sensor 230, .

The air amount sensor 110 is installed at a predetermined position of the intake manifold, detects the amount of air sucked in the state where the engine 100 maintains the start-up state, and provides the controller 300 with information on the amount of the intake air.

The catalyst 200 is composed of a mixed material of ceria (CeO2) and zirconia (ZrO2) and is installed at a predetermined position of the exhaust manifold. The catalyst 200 purifies various harmful substances such as HC, CO and NOx contained in the exhaust gas, (E / M).

The catalyst 200 absorbs oxygen at the air-fuel ratio lean condition of the idling operation and releases the inhaled oxygen at the air-fuel ratio rich condition, thereby oxidizing and reducing the harmful substances of the exhaust gas to provide a purifying function .

The first oxygen sensor 210 is installed on the upstream side of the catalyst 200 and detects the concentration of oxygen contained in the exhaust gas flowing into the catalyst 200 according to the lean and rich control of the air-fuel ratio, To the controller (300).

The second oxygen sensor 220 is installed downstream of the catalyst 200 and detects the concentration of oxygen contained in the exhaust gas purified by the catalyst 200 according to the lean and rich control of the air-fuel ratio, To the controller (300).

The temperature sensor 230 is mounted on the downstream side of the catalyst 200 and provides temperature information of the catalyst 200 to the controller 300.

The controller 300 calculates the fuel amount based on the information of the air amount sensor 110 and feedback controls the air-fuel ratio lean and rich based on the information applied from the first and second oxygen sensors 210 and 220.

The controller 300 controls the temperature of the catalyst 200 from the point at which the signal of the first oxygen sensor 210 installed on the upstream side of the catalyst 200 moves upward after the air- (OSC) of the catalyst 200, which is determined by the delay time until the signal of the second oxygen sensor 220 installed on the downstream side moves upward, is compared with the threshold value, and when the threshold value is exceeded (OSC) is calculated based on the first monitored value when the number of times of occurrence of oxygen uptake occurs once.

If the calculated rate of change exceeds the set threshold value, the contamination counter of the ceria, which is a constituent material of the catalyst 200, is accumulated. If the cumulative counter exceeds the set number of times, 200) or to increase the cumulative counter value for contamination determination.

That is, when the ceria, which is a constituent material of the catalyst 200, is abnormally deteriorated by a foreign substance such as sulfur, the E / M of the HC is normally kept at a favorable value, thereby preventing the output of the failure code of the catalyst 200.

The operation of the present invention including the functions described above will be described in detail with reference to FIG.

When the engine of the vehicle to which the catalyst diagnosis logic according to the present invention is applied keeps the startup ON, the controller 300 analyzes the general control information and determines whether the conditions for monitoring the catalyst 200 are satisfied (S101).

The monitoring of the catalyst 200 proceeds under the condition that the engine 100 maintains the children.

If the monitoring condition of the catalyst 200 is satisfied in step S101, the controller 300 controls the first oxygen sensor 210 and the catalyst 200 installed on the upstream side of the catalyst 200 according to the lean and rich air- (NO in step S102), and the oxygen adsorption capability (OSC) of the catalyst 200 is detected in step S103.

That is, when the signal of the first oxygen sensor 210 installed on the upstream side of the catalyst 200 after the air-fuel ratio is changed from the lean to the rich state under the idle operating condition moves upward, (OSC) of the catalyst 200, which is determined by the delay time up to the point of time when the signal of the second oxygen sensor 220 installed on the second oxygen sensor 220 moves upward.

Then, it is determined whether the detected oxygen absorption / discharge capacity (OSC) exceeds a predetermined failure determination threshold value (S104). If the failure determination threshold value is not exceeded, the process returns to step S102, (OSC) is repeatedly detected. When the number of times exceeding the failure determination threshold value is detected, the number of times that the failure determination threshold value is exceeded based on the value of the first detected oxygen absorption and emission capability (OSC) The rate of change of the ability (OSC) is calculated (S105).

As shown in FIG. 3, the calculation of the rate of change of the oxygen absorption and desorption capability (OSC) is based on the first ①, the rate of change with the second ②, the rate of change with the third ③, And the rate of change with ⑥.

If the result of the calculation of the oxygen absorption / desorption capability (OSC) change rate in S105 is in a state exceeding a predetermined threshold value, for example, 0.7 seconds (S106), and if the rate of change exceeding the threshold value is calculated, It is determined that the ceria, which is a constituent material, is contaminated by the poor fuel component, and the pollution counter is increased (S107).

If it is judged in S108 that the pollution counter which has been increased in S107 exceeds the set reference frequency, for example, twice, the HC purification performance of the catalyst 200 is maintained normally, It is determined that there is an abnormality in the oxygen absorption / desorption capability (OSC) of the ceria, which is a constituent material of the catalyst 200, by the fuel component, and the malfunction determination reference value is adjusted upward to avoid the malfunction determination of the catalyst 200 S110).

In other words, even when the ceria, which is a constituent material of the catalyst 200, does not normally exhibit the oxygen absorption / desorption ability due to the coarse fuel component, the HC purification of the catalyst 200 is normally maintained and the emission is stably ensured. And prevents the occurrence of a failure judgment easily.

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, It is included in the scope of right.

1 is a view schematically showing a catalyst diagnosis apparatus for a vehicle according to an embodiment of the present invention.

2 is a flowchart illustrating a catalyst diagnosis procedure in a vehicle according to an embodiment of the present invention.

3 is a diagram illustrating a procedure for calculating the rate of change of the OSC in the catalyst diagnosis of the vehicle according to the embodiment of the present invention.

4 is a view showing the HC purification capability measurement of a catalyst applied to a conventional vehicle.

5 is a graph showing a comparison of OSC deviation between high and low temperature products according to the temperature of the catalyst.

Description of the Related Art

100: engine 110: air quantity sensor

200: catalyst 210: first oxygen sensor

220: second oxygen sensor 230: temperature sensor

300: controller

Claims (4)

A catalyst for purifying the exhaust gas by an oxidation and reduction action; First and second oxygen sensors provided upstream and downstream of the catalyst, respectively, for detecting the oxygen concentration according to the lean / rich transition of the air-fuel ratio; The oxygen absorption capacity of the catalyst is detected under the idle condition and is compared with the threshold value. If the value of the first detected oxygen absorption / desorption ability exceeds the threshold value by calculating the rate of change of the number of times exceeding the threshold value, A controller for avoiding a catalyst failure diagnosis when the contamination determination counter exceeds a set number of times and adjusting a threshold value of the failure determination upward; And a catalytic converter connected to the catalytic converter. The method according to claim 1, The oxygen absorption capacity of the catalyst is determined by the delay time from when the signal of the first oxygen sensor moves up to when the signal of the second oxygen sensor moves up after the air-fuel ratio is changed from lean to rich in the idle operating condition Characterized in that the catalytic diagnostic device of the vehicle. The method according to claim 1, Wherein the controller is configured to avoid the catalyst malfunction determination because the emission of the catalyst is maintained stably even if the oxygen absorption / desorption capability of the ceria, which is a catalyst constituent, is lowered due to the coarse fuel component. Analyzing information of the first and second oxygen sensors under idle conditions, detecting a value of an OSC (oxygen absorption / desorption capability) of each catalyst for each cycle, and comparing the value with an established failure determination threshold value; Calculating a rate of change of the OSC (oxygen absorptive emission capability) value based on the first detected OSC (oxygen absorptive capacity) value when the OSC (oxygen absorptive capacity) value of the catalyst exceeds a failure determination threshold value; If the calculated rate of change exceeds a predetermined reference value, determining that the ceria, which is a catalyst component, is contaminated by the fuel component and increasing the pollution counter; Determining that the ceria is contaminated by a poor fuel component when the cumulative value of the contamination counter for the ceria exceeds a set number of times, and that the emission of the catalyst is maintained to be normal, thereby avoiding a malfunction determination for the catalyst; Wherein the catalyst is a catalyst.

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