KR101198783B1 - Exhaust gas post processing method and system performing this - Google Patents

Abstract

Exhaust gas after-treatment method according to an embodiment of the present invention, the step of detecting the first detection particulate matter collected by using the differential pressure of the front and rear end of the diesel particulate filter at the time before starting off, after starting off, when restarting, Detecting a second detected particulate matter collection amount by using a differential pressure before and after the diesel particulate filter; and when a difference value between the first sensed particulate matter collection amount and the second sensed particulate matter collection amount exceeds a first predetermined value, Calculating a first predictive particulate matter collection amount of the diesel particulate filter using a consumption amount, an engine RPM, and a temperature value of the diesel particulate filter, and a first predicted particulate matter collection amount for regenerating the diesel particulate filter Regenerating the diesel particulate filter, if the regeneration reference collection amount is exceeded.
Therefore, the amount of soot trapped by the diesel soot filter in the section (predicted section in FIG. 3) that is actually detected by the parking effect (parking effect) upon restarting the fuel soot, engine PM, and exhaust The gas temperature can be used to predict relatively accurately. In addition, it is possible to prevent excessive collection of soot in the diesel particulate filter, thereby improving durability and preventing damage during regeneration.

Description

Exhaust gas aftertreatment method and system for performing the same {EXHAUST GAS POST PROCESSING METHOD AND SYSTEM PERFORMING THIS}

The present invention relates to an exhaust gas aftertreatment method and system, and more particularly, to an exhaust gas aftertreatment method and system for regenerating a diesel filtration filter (DPF) to collect and remove particulate matter contained in the exhaust gas. will be.

In the case of diesel vehicles with relatively high emissions of harmful exhaust gases, the reduction of harmful substances is a very important problem. In particular, there is a demand for reduction of particulate matter (PM), which is mainly caused by incomplete combustion of fuels.

Various techniques have been introduced to reduce particulate matter, and there are diesel particulate filters (DPFs) that collect particulate matter in exhaust gas components and remove particulate matter by heating the collected particulate matter above the ignition temperature. .

In the diesel filtration filter, smooth regeneration is possible in a state where the exhaust gas temperature is high, such as in a high speed or high load state, but the temperature of the exhaust gas must be forcibly raised for regeneration under a low load operating condition.

In order to raise the exhaust gas temperature, post injection is performed to inject fuel again after the combustion is completed, so that the exhaust gas is discharged in a diesel oxidation catalyst (DOC) disposed upstream of the DPF. Raise the temperature.

In order to regenerate the diesel particulate filter, front and rear differential pressures are used. If the differential pressure is equal to or higher than a set value, regeneration is performed.

However, after starting off, when the engine temperature is cold restarted, the differential pressure of the front and rear ends of the diesel particulate filter is detected to be low, and the smoke is actually excessively collected, and the temperature is excessively high during regeneration. This may reduce or damage the durability of the diesel particulate filter.

Accordingly, the present invention provides an exhaust gas after-treatment method and system for preventing exhaust from being excessively collected in the diesel particulate filter during cold restart after the engine is turned off, thereby preventing the durability from being damaged or broken. To provide.

Exhaust gas after-treatment method according to the present invention, the step of detecting the first detection soot collection amount using the front and rear differential pressure of the diesel particulate filter at the time before starting off, after the start-off, when restarting, the diesel particulate filter Detecting the second sensed smoke collection amount using the front-rear pressure difference of when the difference value between the first sensed smoke collection amount and the second sensed smoke collection amount exceeds a set value, the fuel consumption amount, the engine And calculating a predicted particulate matter collection amount of the diesel particulate filter using a temperature value of the diesel particulate filter, and when the predicted particulate matter collection amount exceeds a regeneration reference amount for regenerating the diesel particulate filter, the diesel particulate matter. Playing the filter.

Comparing the second sensed smoke collection amount and the predicted smoke collection amount, and when the second sensed smoke collection amount exceeds the predicted smoke collection amount, comparing the second reference smoke collection amount with the reproduction reference collection amount And regenerating the diesel particulate filter when the second sensing particulate collection amount exceeds the regeneration reference collection amount.

The higher the fuel consumption and the engine RPM, the higher the predicted particulate matter collection, and the higher the temperature value of the diesel particulate filter, the more natural regeneration increases and the lower the predicted particulate matter collection.

During the regeneration of the diesel particulate filter, the temperature of the diesel particulate filter is maintained at a set temperature for a set time to remove the collected soot.

The predicted soot collection amount is calculated by adding the amount of soot collection that reflects the fuel consumption amount, engine RPM, and the temperature value of the diesel particulate filter to the first sensed soot collection amount.

As described above, in the exhaust gas post-treatment method according to the present invention, the soot collected in the diesel particulate filter in a section (a prediction section in FIG. 3) where the amount of soot trapping actually detected by the parking effect is restarted. The trapped amount can be estimated relatively accurately using the fuel consumption amount, engine RPM, and exhaust gas temperature.

In addition, it is possible to prevent excessive collection of soot in the diesel particulate filter, thereby improving durability and preventing damage during regeneration.

1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.
2 is a flowchart for controlling the exhaust gas post-treatment method according to an embodiment of the present invention.
3 is a graph showing the collection amount of the diesel particulate filter according to the mileage (fuel consumption) according to an embodiment of the present invention.
4 is a graph for predicting the amount of diesel particulate filter collected according to the mileage (fuel consumption) according to an embodiment of the present invention.

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

1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.

Referring to FIG. 1, the exhaust gas aftertreatment system includes an engine 100, an injector 140, a diesel particulate filter 110, a differential pressure sensor 120, a temperature sensor 130, a speed (distance) sensor 160, It is configured to include a flow sensor 170, and the controller 150.

The engine 100 burns fuel injected from the injector 140 to produce power, and the exhaust gas is discharged through the exhaust line.

In addition, the diesel particulate filter 110 is installed in the exhaust line, the diesel particulate filter 110 collects and removes particulate matter (soot) contained in the exhaust gas.

The differential pressure sensor 120 senses the differential pressure at the front and rear ends of the diesel particulate filter 110, and the controller controls the differential pressure signal detected by the differential pressure sensor 120 to collect the particulate matter collected in the diesel particulate filter 110. Calculate with the collection amount.

In addition, the temperature sensor 130, detects the temperature of the exhaust gas flowing into the inlet of the diesel particulate filter (110).

The controller 150 detects the driving distance, cumulative driving distance, and fuel consumption of the vehicle from the speed sensor 160 and the flow sensor 170, and calculates the amount of particulate matter collected from the differential pressure sensor 120. do.

In an embodiment of the present invention, the control unit 150 controls the injector 140 according to the mileage, fuel consumption, or differential pressure of the vehicle to post-inject the fuel, thereby detecting the exhaust gas detected by the temperature sensor 130. The diesel particulate filter 110 is regenerated by maintaining the temperature of the gas above the set temperature.

The control unit 100 may be implemented as one or more microprocessors operated by a set program, and the set program may be configured to perform each step included in the deceleration control method of the automatic transmission vehicle according to the embodiment of the present invention described below. It can be a series of instructions.

In an embodiment of the present invention, the detection unit for detecting a driving condition of the vehicle may be composed of the differential pressure sensor, the temperature sensor, the speed sensor, and the flow rate sensor.

2 is a flowchart for controlling the exhaust gas post-treatment method according to an embodiment of the present invention, Figure 3 is a graph showing the amount of diesel particulate filter collected according to the mileage (fuel consumption) according to an embodiment of the present invention. to be.

Referring to FIG. 2, in S100, control is started, and in S105, a restart of the engine 100 is detected, and a first sense smoke collection amount detected at a start-off time point and stored in a memory (S1: soot collection immediately before start-off). Amount), and detects the second sensed smoke collection amount (S: soot measurement after restarting) by the differential pressure before and after the diesel particulate filter after starting.

The first detection particulate matter collection amount (S1) is detected by the pressure difference between the front and rear ends of the diesel particulate filter 110 at the time of starting off, and the second particulate matter collection amount (S) is the diesel particulate matter upon restarting. It is detected by the front and rear differential pressure of the filter 110.

A difference occurs between the first sense smoke collection amount S1 and the second detection smoke collection amount S. Referring to FIG. 3, a horizontal axis represents a mileage (fuel consumption), and a vertical axis represents the diesel. It shows the amount of soot collected in the soot filter.

As shown in FIG. 3, the amount of smoke collected at the boundary between the measured section 1 and the predicted section decreases drastically. That is, the amount of smoke collected at the start-off time is high, but the amount of smoke collected during cold start is small.

Between the restart time and the start-off time, the amount of soot trapped is the temperature of the diesel particulate filter 110, the temperature of the exhaust gas, and the like.

Referring back to FIG. 2, in S110, the second detected particulate matter collection amount S1 is subtracted from the first detected particulate matter collection amount S1, and it is determined whether the difference value exceeds the set value A.

When the difference value exceeds the set value A, S115 is executed, the difference value does not exceed the set value A, and S155 is executed.

In S115, the fuel consumption amount, the engine RPM, and the front end temperature T5 and the temperature holding time t of the diesel particulate filter 110 are sensed, and in S120, the first predicted particulates of the diesel particulate filter 110 are detected. Calculate the collection amount Se.

The first predictive particulate matter collection (Se) is a value obtained by adding the particulate matter collection increase (S2) to the first sense particulate matter collection amount (S1), and the particulate matter collection increase (S2) is fuel consumption, engine RPM, and the diesel. It is calculated from the front end temperature T5 and the temperature holding time t of the soot filter.

In fact, the soot collection increase (S2) is a value obtained by subtracting the natural regeneration amount, the higher the front end temperature (T5) of the diesel particulate filter 110, the longer the temperature holding time (t), the natural regeneration amount is Gets bigger

4 is a graph for predicting the amount of diesel particulate filter collected according to the mileage (fuel consumption) according to an embodiment of the present invention.

Referring to FIG. 4, the horizontal axis is a driving distance (fuel consumption), the vertical axis is a soot collection amount, and if the front end temperature T5 of the diesel particulate filter 110 is 250 degrees Celsius, the increase in the soot collection amount is increased. It is large, the slope of the diesel particulate filter 110 in the front end temperature (T5) is in the range of 250 to 350 degrees Celsius is the middle, the front end temperature (T5) of the diesel particulate filter 110 is 350 degrees Celsius or more Its slope is small.

Referring back to FIG. 2, in S120, the first predictive smoke collection amount Se is calculated by adding the smoke collection increase amount S2 to the first detection smoke collection amount S1, and in S125, the diesel. The second sensed smoke collection amount S detected by the front and rear end pressure difference of the particulate filter 110 is compared with the first predicted smoke collection amount Se.

That is, in S125, when the second detected particulate matter collection amount S is smaller than the first predicted particulate matter collection amount Se, S130 is performed, and the second sensed particulate matter collecting amount S is the first prediction. If it is more than the soot collection amount Se, S155 is performed.

In S130, if the first predicted particulate matter collection Se is equal to or greater than the first renewable reference capture amount SML [X] for regenerating the diesel particulate filter 110, in S135, the fuel is post-injected, The front end temperature of the diesel particulate filter 110 is higher than the set temperature T1 and maintained for a time t1 set in S140.

In S155, when the second detection particulate matter collecting amount S is equal to or greater than the first reproduction reference collecting amount SML [X] for regenerating the diesel particulate filter 110, in S160, the fuel is post-injected, The front end temperature of the diesel particulate filter 110 is higher than the set temperature T1 and maintained for a time t1 set in S165.

As described above, the amount of soot collected in the diesel particulate filter 110 is reduced to a fuel consumption amount in a section in which the amount of soot collected actually detected by the parking effect (parking effect) is small (a prediction section in FIG. 3). , Engine RPM, and exhaust gas temperature can be used to predict relatively accurately.

In addition, it is possible to prevent excessive collection of soot in the diesel particulate filter, thereby improving durability and preventing damage during regeneration.

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.

100: engine
110: diesel particulate filter (DPF)
120: differential pressure sensor
130: Temperature sensor
140: injector
150:
160: speed (distance) sensor
170: flow rate (fuel consumption) sensor

Claims (6)

Detecting the first detection particulate matter collection amount by using the differential pressure before and after the diesel particulate filter at a time before starting is turned off;
After starting off, upon restarting, the second sensing particulate collection amount is detected using the differential pressure before and after the diesel particulate filter;
When the difference value between the first sensed smoke collection amount and the second sensed smoke collection amount exceeds a set value, the predicted smoke of the diesel particulate filter is estimated by using the fuel consumption amount, engine RPM, and the temperature value of the diesel particulate filter. Calculating a collection amount; And
Regenerating the diesel particulate filter when the predicted particulate matter collection amount exceeds a regeneration reference collection amount for regenerating the diesel particulate filter;
Regenerating the diesel particulate filter when a difference value between the first sensed particulate matter collection amount and the second sensed particulate matter collection amount is less than or equal to a predetermined value and the second sensed particulate matter collection amount exceeds the regeneration reference collection amount. ; Exhaust gas after-treatment method comprising a. delete In claim 1,
The higher the fuel consumption amount and the engine RMP, the higher the predicted particulate matter collection amount is,
The exhaust gas after-treatment method, characterized in that as the temperature value of the diesel particulate filter increases, the natural regeneration is increased, and the predicted particulate collection amount decreases. In claim 1,
The predicted smoke collection amount is calculated by adding the fuel consumption amount, the engine RMP, and the increase in the smoke collection reflecting the temperature value of the diesel particulate filter to the first detection particulate collection amount. delete Diesel particulate filter for collecting particulate matter contained in the exhaust gas discharged from the engine; And
A detector detecting a driving condition of the vehicle;
A controller for executing a program set to remove particulate matter collected in the diesel particulate filter according to a driving condition of the vehicle detected by the detector; Including,
The set program, the exhaust gas after-treatment system, characterized in that for performing the method of any one of the first, third, and fourth.

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