KR101209728B1 - Method for determining heat-deterioration of particulate filter - Google Patents

Abstract

Degradation degree determination method of the soot filter according to an embodiment of the present invention is to determine the degree of degradation of the soot filter coated with an oxidation catalyst, after the exhaust filter is completely regenerated by injecting fuel to calculate the exothermic efficiency of the soot filter The degree of deterioration can be determined.
The average temperature of the exhaust gas in the soot filter is within the set temperature range, the differential pressure between the soot filter front and the rear end is within the set pressure range at the end of the regeneration, the idle state has not been maintained for more than the set time, When the modeling value of the residual soot amount is less than the set residual amount, it may be determined that the soot filter is completely regenerated.

Description

Determination method of smoke filter {METHOD FOR DETERMINING HEAT-DETERIORATION OF PARTICULATE FILTER}

The present invention relates to a method for determining the deterioration of a soot filter. More particularly, the present invention relates to a method for determining the deterioration of a soot filter, in which fuel is sprayed after completely regenerating a soot filter coated with an oxidation catalyst. It is about.

In general, the exhaust gas discharged from the engine through the exhaust manifold is guided to a catalytic converter formed in the middle of the exhaust pipe and purified, and the noise is attenuated while passing through the muffler and then released into the atmosphere through the tail pipe. The catalytic converter treats contaminants contained in the exhaust gas. And a soot filter for collecting particulate matter (PM) contained in the exhaust gas is mounted on the exhaust pipe.

Selective Catalytic Reduction (SCR) catalysts are a type of such catalytic converter. Selective catalytic reduction (SCR) devices are termed selective catalytic reduction in the sense that reducing agents such as urea, ammonia, carbon monoxide and hydrocarbons (HC) react better with nitrogen oxides in oxygen and nitrogen oxides. It is becoming.

In addition to this selective catalytic reduction catalyst, the exhaust device uses a soot filter to collect soot contained in the exhaust gas. As such, when an optional catalytic reduction catalyst and a soot filter are used in the exhaust system, two further oxidation catalysts are typically used.

The first oxidation catalyst is typically coated at the front end of the soot filter to oxidize hydrocarbons, carbon monoxide, and nitrogen monoxide contained in the exhaust gas flowing into the soot filter. The heat generated during this oxidation process is used to regenerate the soot filter. Since nitrogen dioxide is used in the regeneration of the soot filter, nitrogen dioxide is insufficient in the exhaust gas delivered to the selective catalytic reduction catalyst, which reduces the purification efficiency of the selective catalytic reduction catalyst. In order to prevent this, a second oxidation catalyst is disposed at the rear of the soot filter to oxidize hydrocarbons, carbon monoxide, and nitrogen monoxide contained in the exhaust gas passing through the soot filter.

In order to determine the deterioration degree of the soot filter, it is necessary to install a temperature sensor in front of the filter part of the soot filter, and determine the deterioration degree of the soot filter using the temperature of the exhaust gas measured by the temperature sensor. However, in the conventional exhaust apparatus, the first oxidation catalyst is coated on the front end of the soot filter (that is, immediately before the filter part), so that it is impossible to mount the temperature sensor on the front end of the filter part of the soot filter. In addition, there is a method of determining the deterioration degree of the soot filter by using a temperature sensor attached to the rear end of the soot filter and using the temperature of the exhaust gas measured by this temperature sensor. As a result, the temperature of the exhaust gas is distorted, making it difficult to determine the degree of deterioration of the soot filter.

Accordingly, the present invention has been made to solve the problems described above, a method of determining the deterioration of the soot filter to determine the degree of deterioration of the soot filter by injecting fuel after completely regenerating the soot filter coated with the oxidation catalyst. To provide.

In order to achieve the above object, the method for determining the deterioration of the soot filter in accordance with an embodiment of the present invention is to determine the degree of degradation of the soot filter coated with an oxidation catalyst, the fuel is injected after the regeneration of the soot filter completely The deterioration degree of the soot filter can be determined by calculating the exothermic efficiency.

The step of completely regenerating the soot filter may be performed by repeating the regeneration at regular intervals.

The average temperature of the exhaust gas in the soot filter shall be within the set temperature range, at the end of regeneration the pressure difference between the front and rear ends of the soot filter shall be within the set pressure range, the idle state shall not be maintained for more than the set time, and the soot When the modeling value of the residual soot amount in the filter satisfies at least one condition of being less than the set residual amount, it may be determined that the soot filter is completely regenerated.

The fuel may be injected after a predetermined time elapses after the soot filter is completely regenerated.

The exothermic efficiency may be calculated by dividing the difference between the front end and the rear end temperatures of the soot filter by the amount of injected fuel.

When the heat generation efficiency is less than the set efficiency, an abnormal code of the soot filter may be generated.

The soot filter is provided in an exhaust device for removing nitrogen oxides, hydrocarbons, carbon monoxide and soot contained in the exhaust gas, and the exhaust device is a hydrocarbon, carbon monoxide contained in the exhaust gas by coating a first oxidation catalyst on its front end. And a second oxidation catalyst that oxidizes nitrogen monoxide primarily and collects soot contained in the exhaust gas, and a second oxidation catalyst provided at a rear end of the soot filter to oxidize hydrocarbon, carbon monoxide and nitrogen monoxide contained in the exhaust gas secondaryly. An optional catalytic reduction catalyst provided at a rear end of the second oxidation catalyst to inject a reducing agent into the exhaust gas, and a selective catalytic reduction catalyst provided at the rear end of the injection module to reduce nitrogen oxides contained in the exhaust gas using the reducing agent; It may include.

The step of completely regenerating the soot filter may be entered when the travel distance of the accumulated vehicle exceeds the set distance. The predetermined period may come when the running distance of the accumulated vehicle after regenerating the particulate filter is more than half of the set distance. The step of completely regenerating the soot filter may be continued if the soot filter is regenerated but not completely regenerated.

As described above, according to the present invention, after completely regenerating the soot filter, fuel may be injected to accurately measure the degree of deterioration of the soot filter.

In addition, by accurately measuring the degree of deterioration of the soot filter, it is possible to prevent deterioration of the exhaust gas and to improve fuel efficiency.

1 is an example of an exhaust apparatus to which the deterioration degree determination method of a soot filter according to an exemplary embodiment of the present invention is applied.
2 is a block diagram of an apparatus for executing a method of determining a deterioration degree of a soot filter according to an exemplary embodiment of the present invention.
3 is a flowchart illustrating a method of determining a deterioration degree of a soot filter according to an exemplary embodiment of the present invention.
4 is a graph illustrating temperature values measured by the first and second temperature sensors when the soot is deposited on the particulate filter.
FIG. 5 is a graph illustrating temperature values measured by the first and second temperature sensors when no soot is deposited on the soot filter, and temperature values measured by the second temperature sensor when the soot filter is deteriorated.
6 is a graph showing the reproduction efficiency according to the reproduction time.

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

1 is an example of an exhaust apparatus to which the deterioration degree determination method of a soot filter according to an exemplary embodiment of the present invention is applied.

As shown in FIG. 1, the exhaust device includes a soot filter 20, a second oxidation catalyst 30, and an injection module 40 in which a first oxidation catalyst 22 is coated on a front end thereof on an exhaust pipe 10. And an optional catalytic reduction catalyst 50 are optionally arranged. Such an exhaust device removes harmful substances contained in exhaust gases generated from an engine (not shown).

The engine combusts a mixture of fuel and air to convert chemical energy into mechanical energy. The engine is connected to an intake manifold (not shown) to receive air into the combustion chamber, and the engine is connected to an exhaust manifold (not shown) so that the exhaust gas generated in the combustion process is collected in the exhaust manifold to the outside of the vehicle. Will be discharged. The combustion chamber is equipped with an injector 90 to inject fuel into the combustion chamber. Additionally, an additional injector may be mounted at the front end of the soot filter 20 mounted on the exhaust pipe 10 to directly inject fuel into the exhaust gas.

The exhaust pipe 10 is connected to the exhaust manifold to exhaust the exhaust gas to the outside of the vehicle. On the exhaust pipe 10, a soot filter 20, a second oxidation catalyst 30, an injection module 40, and a selective catalytic reduction catalyst 50 are sequentially installed from an engine and include hydrocarbons and carbon monoxide contained in exhaust gas. And nitrogen oxides are removed and the soot contained in the exhaust gas is collected.

The soot filter 20 is mounted on the exhaust pipe 10 and collects particulate matter (PM) contained in the exhaust gas discharged through the exhaust pipe 10. In addition, a first oxidation catalyst 22 is coated on the front end of the particulate filter 20 to oxidize hydrocarbons and carbon monoxide contained in the exhaust gas to carbon dioxide, and nitrogen monoxide contained in the exhaust gas to nitrogen dioxide. Oxidize. Here, it is illustrated that the first oxidation catalyst 22 is coated on the front end of the soot filter 20, but is not limited thereto. That is, the first oxidation catalyst 22 may be coated on the entire area of the soot filter 20 or may be coated on a predetermined area.

On the other hand, the differential pressure sensor 80 is mounted on the front end and the rear end of the soot filter 20. The differential pressure sensor 80 measures the pressure difference between the front end portion and the rear end portion of the soot filter 20 and transmits a signal thereof to the controller 100. The controller 100 may control to regenerate the soot filter 20 when the pressure difference measured by the differential pressure sensor 80 is greater than or equal to a set value. In this case, the soot collected in the soot filter 20 may be burned by post-injection of the fuel in the injector 90.

The front end of the first oxidation catalyst 22 of the soot filter 20 is equipped with a first temperature sensor 60 to measure the temperature of the exhaust gas flowing into the soot filter 20.

In addition, a second temperature sensor 70 is mounted at the rear end of the soot filter 20 to measure the temperature of the exhaust gas from the soot filter 20.

The second oxidation catalyst 30 is attached to the rear end of the soot filter 20. The second oxidation catalyst 30 oxidizes hydrocarbons and carbon monoxide contained in the exhaust gas flowing out of the soot filter 20 into carbon dioxide, and oxidizes nitrogen monoxide contained in the exhaust gas into nitrogen dioxide. Nitrogen dioxide oxidized in the second oxidation catalyst 30 is supplied to the selective catalytic reduction catalyst 50 and used to reduce nitrogen oxides.

An injection module 40 is provided on the exhaust pipe 10 at the rear end of the second oxidation catalyst 30. The injection module 40 injects a reducing agent to the exhaust gas oxidized by the second oxidation catalyst 30. The reducing agent may be ammonia. In general, the injection module 40 sprays urea and the injected urea is decomposed into ammonia.

A selective catalytic reduction (SCR) catalyst 50 is mounted on the exhaust pipe 10 at the rear end of the injection module 40 so that the exhaust gas mixed with the reducing agent is supplied to the SCR catalyst 50. The SCR catalyst 50 reduces the nitrogen oxides in the exhaust gas to nitrogen gas to reduce the nitrogen oxides in the exhaust gas.

2 is a block diagram of an apparatus for executing a method of determining a deterioration degree of a soot filter according to an exemplary embodiment of the present invention.

As shown in FIG. 2, an apparatus for performing a method for determining the deterioration of a soot filter according to an exemplary embodiment of the present invention includes first and second temperature sensors 60 and 70, a differential pressure sensor 80, and a timer 85. , The controller 100, the injection module 40, and the injector 90. In addition, the apparatus may further include a plurality of sensors (eg, an oxygen sensor, an engine speed sensor, etc.).

As illustrated in FIG. 1, the first temperature sensor 60 measures the temperature of the exhaust gas that is mounted at the front of the soot filter 20 and flows into the soot filter 20, and transmits a signal corresponding thereto. 100).

As illustrated in FIG. 1, the second temperature sensor 70 is mounted at the rear end of the soot filter 20 to measure the temperature of the exhaust gas emitted from the soot filter 20, and transmits a signal corresponding thereto to the controller 100. To be sent).

As shown in FIG. 1, the differential pressure sensor 80 is mounted at the front end and the rear end of the soot filter 20 to measure the difference between the front end pressure and the rear end pressure of the soot filter 20. The signal is transmitted to the controller 100.

The timer 85 is electrically connected to the control unit 100 to turn on when the smoke filter 20 is completely regenerated, and to turn off when the set time elapses.

The control unit 100 performs a method for determining the deterioration degree of the soot filter 20 according to an embodiment of the present invention based on the values measured by the sensors 60, 70, and 80 and the value measured by the timer 85. do. To this end, the control unit 100 may control the injection module 40 to inject a reducing agent into the exhaust gas, and the injector 90 post injection to regenerate the soot filter 20 or calculate the exothermic efficiency. Can be controlled.

3 is a flowchart illustrating a method of determining a deterioration degree of a soot filter according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the method for determining a deterioration degree of a soot filter according to an exemplary embodiment of the present invention is started by the controller 100 integrating a driving distance of a vehicle (S200). The mileage integration of such a vehicle continues until the accumulated mileage exceeds the set distance. That is, the controller 100 determines whether the accumulated travel distance of the vehicle exceeds the set distance (S210).

When the driving distance of the vehicle accumulated in step S210 is less than or equal to the set distance, the controller 100 continuously accumulates the driving distance of the vehicle (S200).

When the running distance of the vehicle accumulated in the step S210 exceeds the set distance, the control unit 100 performs a complete regeneration of the soot filter 20 in order to proceed with the method for determining the deterioration degree of the soot filter according to the embodiment of the present invention. Perform (S220). Complete regeneration of the soot filter 20 is similar to that of a conventional soot filter 20. That is, the control unit 100 injects fuel into the exhaust gas or the combustion chamber to increase the temperature of the exhaust gas, and burns the soot collected in the soot filter. However, the time required for complete regeneration of the soot filter 20 is longer than the regeneration time of the conventional soot filter 20, as shown in FIG. That is, by setting a long time for regeneration of the soot filter 20, the regeneration efficiency is made close to 100%. The time required for complete regeneration of the soot filter 20 may be set by those skilled in the art in consideration of various variables (fuel efficiency, regeneration efficiency, exhaust gas temperature, etc.).

Thereafter, the control unit 100 determines whether the complete regeneration of the soot filter 20 has ended (S230). As described above, even when the exhaust filter 20 is completely regenerated by setting the regeneration time of the soot filter 20 long, the soot filter 20 may not be completely reproduced. Therefore, the controller 100 determines whether the following conditions are satisfied to determine whether the complete regeneration of the soot filter 20 is finished.

1) The average temperature of the exhaust gas in the soot filter should be within the set temperature range.

Here, the average temperature of the exhaust gas in the soot filter refers to the average value of the exhaust gas temperatures measured by the first and second temperature sensors. In addition, the said set temperature range means the case within +/- 50 degreeC of a regeneration target temperature value, and a regeneration target temperature value is set by the designer.

2) At the end of regeneration, the differential pressure at the front and rear of the soot filter should be within the set pressure range.

Here, the reproduction end time point refers to a time point when the complete reproduction time shown in FIG. 6 ends after the reproduction of the soot filter starts. In addition, the set pressure range refers to a case within ± 20% of the differential pressure between the front and rear ends of the soot filter in the initial state. The differential pressures at the front and rear ends of the soot filter in the initial state are set in a two-dimensional map according to the amount of exhaust gas passing through the soot filter in the initial state and the temperature of the exhaust gas. Alternatively, the differential pressure between the front end and the rear end of the soot filter in the initial state may be measured directly through the differential pressure sensor 80.

3) The engine shall not run for more than the set time in idle state

The set time may be 100 seconds. When the engine is running at idle for a set time, the values measured by the sensors may come out differently from those measured under normal conditions. In this case, therefore, it is prohibited to judge that the soot filter is completely regenerated.

4) The modeling value of residual soot amount in soot filter is less than set residual amount.

The modeling value of the residual soot amount in the soot filter is prepared as a map according to the temperature during regeneration, the amount of nitrogen dioxide generated, and the soot amount at the start of regeneration, and the set residual amount may be 0.5 g / l.

If the complete regeneration of the soot filter 20 is not finished in step S230, the control unit 100 sets the driving distance to an offset value (S320) and again sets the driving distance of the vehicle (S200). In the case of normal regeneration, the soot filter is regenerated when the running distance of the vehicle accumulated from 0km exceeds the set distance.However, when the complete regeneration is not finished, the accumulated distance of the vehicle from the offset value is set to the set distance. When exceeding, the total regeneration of the soot filter 20 is performed. That is, the complete regeneration of the soot filter 20 is shortened by setting the complete regeneration cycle of the soot filter 20 short. The offset value may be 50% of the set distance.

When the complete regeneration of the soot filter 20 is terminated in the step S230, the controller 100 resets the driving distance of the accumulated vehicle (that is, sets the driving distance of the vehicle to "0") (S240). Turn on (85). This timer 85 measures the elapsed time from the time point at which complete reproduction is finished (S250).

Thereafter, the control unit 100 determines whether the time elapsed from the time point at which the complete reproduction ends is more than the set time (S260).

If the time elapsed from the time point at which the complete reproduction is finished in step S260 is less than the set time, the timer 85 continuously measures the elapsed time (S250).

If the time elapsed from the end of the complete regeneration in step S260 is greater than or equal to the set time, the control unit 100 turns off the timer 85 and injects fuel through the injector 90 (S270).

After that, the control unit 100 calculates the heating efficiency (S280).

4 is a graph illustrating temperature values measured by the first and second temperature sensors when soot is deposited in the soot filter, and FIG. 5 is measured by the first and second temperature sensors when soot is not deposited in the soot filter. It is a graph showing the temperature value measured by the second temperature sensor when one temperature value and the soot filter is deteriorated.

4 and 5, the solid line indicates the temperature of the exhaust gas measured by the first temperature sensor 60, and the dashed line indicates the temperature of the exhaust gas measured by the second temperature sensor 70. In addition, the dotted line in FIG. 5 is the temperature of the exhaust gas measured by the second temperature sensor 70 when the soot filter 20 is deteriorated. 4 and 5, when there is a soot in the soot filter 20 (see FIG. 4), the soot is burned to raise the rear temperature of the soot filter 20 (that is, referring to FIG. 7, FIG. 4). The dashed-dotted line is higher in temperature than the dashed-dotted line in FIG. 5). Therefore, in order to calculate the heat generation efficiency of the soot filter 20, the soot filter 20 must be completely regenerated.

Comparing the dashed and dashed lines in FIG. 5, it can be seen that the heat generation efficiency is lowered as the soot filter 20 deteriorates. That is, the temperature of the dotted line is lower than the temperature of the dashed line. Therefore, the heat generation efficiency of the soot filter is calculated by dividing the difference between the front end and the rear end temperature of the soot filter by the amount of injected fuel. In other words, if the difference between the front and rear end of the soot filter is small, the heat generation efficiency of the soot filter is low.

Thereafter, the control unit 100 determines whether the heating efficiency is less than the set efficiency (S290).

If the heating efficiency is greater than or equal to the set efficiency in step S290, the heating efficiency is stored in the control unit 100 (S310), and the method for determining the deterioration degree of the soot filter according to the exemplary embodiment of the present invention is terminated. In this way, the stored heat generation efficiency corresponds to the degree of deterioration of the soot filter 20. That is, the lower the heat generation efficiency, the more deterioration has progressed.

If the heating efficiency is less than the set efficiency in step S290, the control unit 100 determines that there is an error in the soot filter 20 (S300), and generates an error code of the soot filter. In addition, it is also possible to ignite the warning lights on the instrument panel of the vehicle.

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.

Claims (9)

In the deterioration degree determination method of the soot filter coated with an oxidation catalyst,
After completely regenerating the soot filter, the fuel is injected to calculate the exothermic efficiency to determine the degree of deterioration of the soot filter,
And the fuel is injected when a predetermined time elapses after it is determined that the soot filter is completely regenerated. The method of claim 1,
And completely regenerating the soot filter is performed by repeating the regeneration every predetermined period. The method of claim 1,
The average temperature of the exhaust gas in the soot filter shall be within the set temperature range, at the end of regeneration the pressure difference between the front and rear ends of the soot filter shall be within the set pressure range, the idle state shall not be maintained for more than the set time, and the soot And determining that the soot filter is completely regenerated when the modeling value of the residual soot amount in the filter satisfies at least one condition of being less than the set residual amount. delete The method of claim 1,
The exothermic efficiency is calculated as a value obtained by dividing the difference between the front end and the rear end temperature of the soot filter by the amount of injected fuel. 6. The method of claim 5,
If the heat generation efficiency is less than the set efficiency, the deterioration degree of the smoke filter, characterized in that for generating an abnormal code of the smoke filter. The method according to any one of claims 1, 2, 3, 5 or 6,
The soot filter is provided in an exhaust device for removing nitrogen oxides, hydrocarbons, carbon monoxide and soot contained in the exhaust gas,
The exhaust device is a soot filter that is coated on the front end of the first oxidation catalyst to oxidize hydrocarbon, carbon monoxide and nitrogen monoxide contained in the exhaust gas primarily, and collects the soot contained in the exhaust gas, and a rear end of the soot filter. A second oxidation catalyst provided in the exhaust gas for secondary oxidation of hydrocarbons, carbon monoxide and nitrogen monoxide contained in the exhaust gas, an injection module provided at a rear end of the second oxidation catalyst to inject a reducing agent into the exhaust gas, The deterioration degree of the soot filter comprising a selective catalytic reduction catalyst for reducing the nitrogen oxide contained in the exhaust gas by using a reducing agent at the rear end. The method of claim 2,
And completely regenerating the smoke filter when the accumulated travel distance of the accumulated vehicle exceeds a set distance. The method of claim 8,
And wherein the predetermined period arrives when the running distance of the integrated vehicle after regenerating the smoke filter is more than half of the set distance.

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