KR102539410B1 - Method for Activation of Vehicle Aftertreatment System Using Exhaust Gas Temperature Increase - Google Patents

Abstract

According to the present invention, a method for activating a vehicle exhaust gas reduction apparatus using an exhaust gas temperature increase realized in a vehicle exhaust gas reduction apparatus (1) is able to detect one or more of an error code, battery voltage, and exhaust pressure as engine start information when the engine is started (IG On), detect one or more of a burner front/rear end exhaust temperature (T0/T1) after the engine is started (IG On) and a DPF front/rear end exhaust temperature (T2/T3) and a vehicle speed as driving information, heat the exhaust gas for a certain period (G) or up to a target temperature (H) by the combustion flame of a burner (40) and exothermic reactions through the ignition of the igniter and the fuel supply so that the exhaust gas's temperature can be increased in accordance with the upper limit threshold value range of the DPF rear end exhaust temperature (T3), rapidly increase the exhaust gas temperature to 200℃ or over, improve the nitrogen oxide (NOx) reduction performance, and especially rapidly activate an NOx sensor (50) as well, thereby precisely calculating the urea spray volume.

Description

Method for Activation of Vehicle Aftertreatment System Using Exhaust Gas Temperature Increase}

The present invention relates to a control of a vehicle exhaust gas reduction device, and more particularly, to a method for activating a vehicle exhaust gas reduction device in which nitrogen oxide reduction is improved by quickly converting an inactive state due to a low exhaust gas temperature into an active state by increasing the exhaust gas temperature. will be.

In general, a vehicle is equipped with an exhaust gas reduction device, and the exhaust gas reduction device reduces particulate matter and nitrogen oxides included in exhaust gas.

For example, the exhaust gas reduction device uses a selective catalytic reduction (Selective Catalytic Reduction) that removes NOx by a reduction action of urea, and a Diesel Particulate DPF (Diesel Particulate Regeneration) that collects and burns PM (particulate matter). filter) is used. In this case, the Regeneration is an operation that periodically removes collected soot using HC injection and exothermic reaction.

In particular, the selective reduction catalyst reacts nitrogen oxides (NOx-NO, NO2) contained in the exhaust gas with a reducing agent (NH3) and a denitration catalyst to reduce them to nitrogen (N2) and water (H2O) harmless to the human body and discharge them. As a device, it is mainly used as a selective reduction catalyst for exhaust gas reduction devices.

Therefore, the exhaust gas reduction device is required to evaluate the performance of a selective reduction catalyst (ie, SCR) for nitrogen oxide reduction.

To this end, the exhaust gas reduction device exhibits optimal catalytic performance only when the exhaust gas temperature is 200 ° C or higher. This is because it can be thermally decomposed at ° C and hydrolyzed at 200 ° C or higher to produce ammonia (NH 3 ) as a reducing agent.

Japanese Patent Publication JP 2013-189900 A

However, since the activation state of the exhaust gas reduction device requires an exhaust gas temperature of 200° C. or higher as the catalyst (SCR) activation condition, the result of the activation temperature condition is limited in satisfying all of the various operating conditions of the vehicle.

For example, in order to raise the exhaust gas temperature of a vehicle to 200℃ or higher, a certain engine load and vehicle speed or higher are required. In the low-temperature region of exhaust gas such as region or early start, low-speed operation, short section driving, and stop-and-go driving, the temperature of the selective reduction catalyst is difficult to rise above 200 ° C, and the nitrogen oxide reduction efficiency is inevitably reduced.

Accordingly, an object of the present invention in consideration of the above points is to provide an exhaust gas reduction device activation method for enabling catalyst activation of DPF and SCR by rapidly increasing the low exhaust gas temperature.

In order to achieve the above object, the exhaust gas reduction device activation method using the exhaust gas temperature increase of the present invention includes the step of checking the vehicle condition by error code, battery voltage and exhaust pressure after starting the vehicle (IG On) (S10), burner burner (40) Checking the temperature of the front exhaust temperature (To) and the first set temperature (C) (S20), if the exhaust temperature (To) of the front end of the burner 40 is smaller than the first set temperature (C) , The exhaust temperature (T1) at the rear of the burner, the exhaust temperature (T2) at the front of the DPF, the exhaust temperature (T3) at the rear of the DPF, and the second set temperature (D). Temperature confirmation step (S30), When the exhaust temperature of the three points is smaller than the second set temperature (D) and the vehicle speed is greater than the predetermined speed, checking whether the exhaust temperature (T3) at the rear end of the DPF is within a predetermined range (S40); When the exhaust temperature (T3) at the rear end of the DPF is less than the third set temperature (F), the igniter ignition and fuel injection are controlled (S50) and the igniter ignition and fuel injection are controlled. , It is characterized in that it ends when a predetermined time elapses or when the exhaust temperature T3 at the rear end of the DPF is greater than the fourth set temperature H, which is the upper limit temperature at the rear end of the DPF.

Activation control using the temperature increase of the exhaust gas implemented by the vehicle exhaust gas reduction device of the present invention implements the following actions and effects.

First, by rapidly increasing the temperature of the exhaust gas, it is possible to simultaneously activate the selective reduction catalyst (SCR) as well as improve regeneration performance by activating the DPF.

Second, by determining the igniter ignition and fuel injection timing by the exhaust gas temperature (T3) at the rear of the DPF, the burner ignition timing is quickly and accurately determined with the temperature of a single point.

Third, by limiting the fuel injection control time after ignition to a certain time, it is possible to prevent overheating and to save the amount of fuel and urea water used.

1 is a flow chart of a method for activating an exhaust gas reduction device using elevated exhaust gas temperature according to the present invention, and FIG. 2 is a configuration diagram of a vehicle exhaust gas reduction device in which DPF and SCR are activated by raising the exhaust gas temperature according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and these embodiments can be implemented in various different forms by those skilled in the art as an example. It is not limited to the embodiment of

Referring to FIG. 1, the exhaust gas reduction device activation method using the exhaust gas temperature increase checks the vehicle state (S10) for the operation of the vehicle exhaust gas reduction device (1) (see FIG. 2), and then the exhaust gas temperature condition (S20) When the exhaust gas reduction device activation condition (S30) and the burner operating condition (S40) are satisfied, the burner operation (S50 to S60) is performed in such a way.

In particular, in the burner operating steps (S50 to S60), the burner flame (or heater) quickly raises the exhaust gas temperature required for activating the selective reduction catalyst (SCR) to 200° C. or higher along with activating the DPF.

Therefore, the exhaust gas reduction device activation method using the exhaust gas temperature increase utilizes the burner (igniter + fuel injection) of the existing DPF system to increase the exhaust gas temperature by flame combustion. Apart from driving conditions such as / road condition / engine load condition, activation of SCR can be advanced along with DPF (10A) (see FIG. 2) in the low-temperature region of exhaust gas generated during driving.

Therefore, the exhaust gas reduction device activation method using the exhaust gas temperature increase can advance the activation of the NOx sensor 50 (see FIG. 2) through the exhaust gas temperature increase, and furthermore, the exact number of elements for the selective reduction catalyst (SCR) (Urea) Make it possible to calculate the injection amount.

Referring to FIG. 2 , the vehicle exhaust gas reduction device 1 includes an exhaust pipe 3, a DPF 10A, sensors 20, 30, and 50, a burner 40, and a controller 60. In this case, in the vehicle exhaust gas reduction device 1, the selective reduction catalyst (SCR) installed at the rear end of the DPF (10A) and the dosing control unit (DCU) control the urea solution (Urea) to the inside of the exhaust pipe (3). A urea injection device with a urea injector may be included.

For example, the exhaust pipe 3 is a passage through which exhaust gas from an engine of a vehicle flows.

For example, the DPF (Diesel Particulate Filter) collects a certain amount of PM (particulate matter) and periodically regenerates it. The burner 40 generates a combustion flame by igniter ignition and fuel injection, and the fuel is fuel is supplied to the inside of the burner 40 to generate a combustion flame along with the ignition of the igniter, thereby increasing the temperature of the exhaust gas in the exhaust pipe 3, thereby regenerating the DPF and activating the catalyst (SCR). In this case, the burner may be replaced with a heater or plasma capable of using battery power instead of fuel.

Specifically, the sensors 20, 30, and 50 include an exhaust pressure sensor 20, a temperature sensor 30, and a NOx sensor 50.

For example, the exhaust pressure sensor 20 is installed at the rear end of the burner 40 inside the exhaust pipe 3 and detects the exhaust gas pressure flowing through the exhaust pipe 3 .

For example, the temperature sensor 30 detects temperatures before/after the burner of the DPF 10A and the burner 40, and may also include exhaust gas temperatures before/after the SCR, if necessary.

To this end, the temperature sensor 30 includes a burner rear temperature sensor 30A for detecting a burner rear end temperature of the burner 40 and a burner front end temperature sensor 30a for detecting a burner front end temperature inside the exhaust pipe 3, A DPF front end temperature sensor 30B detecting the front end temperature of the DPF 10A from inside the exhaust pipe 3, and a DPF rear end temperature sensor 30C detecting the rear end temperature of the DPF 10A inside the exhaust pipe 3. ) is composed of In this case, the temperature sensor 30 detects the selective reduction catalyst (SCR) front end temperature (T5) inside the exhaust pipe (3) and the selective reduction catalyst (SCR) rear end temperature (T6) inside the exhaust pipe (3). It may include a temperature sensor before / after the SCR that

For example, the NOx sensor 50 detects the NOx concentration in the exhaust gas, and for this purpose, it is installed at the front end of the burner 40 inside the exhaust pipe 3 to increase NOx in the exhaust gas before passing through the DPF 10A ( NOx_Up) and installed at the rear end of the selective reduction catalyst (SCR) inside the exhaust pipe 3 to detect NOx reduction (NOx_Down) in the exhaust gas.

Specifically, the burner 40 is mounted on the exhaust pipe 3 and is located in front of the DPF 10A. In particular, the fuel supplied from the fuel tank of the vehicle under the control of the controller 60 is operated by the igniter and the burner is ignited. Internal combustion increases the temperature of the exhaust gas at the front end of the DPF (10A). In this case, the burner 40 may be replaced with a heater capable of using battery power instead of fuel.

For example, the controller 60 is linked to the data input unit 60-1, and the data input unit 60-1 includes the exhaust pressure of the exhaust pressure sensor 20 and the exhaust temperature T0 of the burner front temperature sensor 30a. ), the exhaust temperature T1 of the temperature sensor 30A at the rear of the burner, the exhaust temperature T2/T3 of the temperature sensors 30B and 30C before and after the DPF, the NOx detection value of the NOx sensor 50, the filter regeneration button signal, and the timer. etc. are detected as internal information of the vehicle exhaust gas reduction device 1 and provided to the controller 60, and at the same time, an error code, vehicle speed, battery voltage, etc. are detected as external information of the vehicle exhaust gas reduction device 1 and the controller 60 ) is provided.

In particular, the controller 60 sets the detection value of the burner front temperature sensor 30a to T0, the detection value of the burner rear temperature sensor 30A to T1, the DPF front temperature sensor 30B to T2, and the DPF rear temperature sensor 30B to T2. The detection value of (30C) is defined as T3, and T0, T1, T2, and T3 are applied as exhaust gas temperature increase variables for activating the exhaust gas reduction device.

Furthermore, the controller 60 defines the front/rear temperature sensor detection values for the SCR as exhaust temperatures T5/T6, and the T5 and T6 together with T0, T1, T2, and T3 exhaust gas for activating the exhaust gas reduction device. By applying it as a temperature increase variable, it is possible to more precisely control the temperature of the exhaust gas temperature increase.

Therefore, the controller 60 has a data storage memory of the data input unit 60-1 and operates as a central processing unit that performs an exhaust gas temperature raising algorithm based on internal/external information of the data input unit 60-1. . In this case, the controller 60 provides the activation state of the NOx sensor 50 to the DCU so that the DCU can calculate an accurate urea solution injection amount and control the urea solution injector.

Hereinafter, a method for activating a catalyst using an elevated temperature of exhaust gas will be described in detail with reference to FIG. 2 . In this case, the control subject is the controller 60 and the control target is the burner 40 .

First, the controller 60 performs the vehicle state step of S10 when the engine is started (IG On) by the key on (Key On), and for this, as shown in FIG. Read voltage and exhaust pressure. In this case, the error code includes an On Board Diagnosis (OBD) code of the exhaust gas reduction device 1 together with an error state of a component that disables the operation of the vehicle exhaust gas reduction device 1, and the battery voltage is is the vehicle battery voltage, and the exhaust pressure is the pressure inside the exhaust pipe.

In this way, the controller 60 detects the error code, the battery voltage, and the exhaust pressure as engine starting information when the engine is started (IG On) to check the exhaust gas (NOx) generation condition. Starting the engine means starting the vehicle.

Exhaust gas (NOx) generation conditions:

No error code & battery voltage > A & exhaust pressure > B, (&=AND)

Here, “battery voltage” and “exhaust pressure” are values detected at the present time, respectively, “A” is the battery voltage threshold, and 24.9V of the set range of about 23.9 to 24.9V is applied, and “B” is set to about 0 mbar as the exhaust pressure threshold. Each is a constant voltage and a constant pressure that can be selectively determined.

As a result, if any one of the error code, battery voltage, and exhaust pressure condition is not met, the controller 60 switches to the standby state until the standby time X of S10-1 has elapsed, and then the exhaust gas (NOx) generation situation of S10 Redo the judgment step. In this case, the waiting time X is set to about 1000 ms.

On the other hand, the controller 60 assumes a ready state when all conditions are satisfied through a battery voltage of 24.9V or more and an exhaust pressure of more than 0 mbar without an error code, and then enters the exhaust gas temperature condition determination step of S20.

For example, in determining the exhaust gas temperature condition (S20), the controller 60 reads the exhaust temperature T0 from among the information of the data input unit 60-1 as shown in FIG. 2. In this case, the exhaust temperature T0 is the internal temperature of the exhaust pipe 3 and the front end of the burner, and is an initial temperature value of the exhaust gas flowing through the exhaust pipe 3, and the vehicle speed is the vehicle speed.

From this, the controller 60 applies the initial exhaust gas temperature condition of the vehicle after starting the engine to the T0 exhaust temperature and vehicle speed.

Exhaust gas initial temperature condition: exhaust gas temperature initial value (T0) < C

Here, “exhaust gas temperature initial value (T0)” is the exhaust temperature (T0) at the front of the burner detected at the present time, and “C” is the temperature threshold at the rear of the burner, which is 40°C in the set range of about 30 to 40°C. is applied.

As a result, the controller 60 identifies the case where the initial exhaust gas temperature value of less than 40° C. is satisfied as the initial exhaust gas temperature condition. Subsequently, the controller 60 sets the exhaust gas temperature to the exhaust gas temperature increase variable, exhaust gas temperature T1 at the rear end of the burner, exhaust temperature T2 at the front end of the DPF, and exhaust temperature T3 at the rear end of the DPF, as the exhaust gas reduction device activation condition in S30. It is performed by checking the vehicle speed along with confirmation. In this case, the T1, T2, T3 and vehicle speed are read from the exhaust temperature and vehicle speed of T1, T2, T3 among the information of the data input unit 60-1 as shown in FIG. 2, and the following exhaust gas temperature increase condition is determined.

Exhaust gas temperature increase condition: exhaust gas temperature (T1/T2/T3) > D & vehicle speed > E

Here, “exhaust gas temperature (T1/T2/T3)” is the exhaust temperature (T1) at the rear of the burner, the exhaust temperature (T2) at the front of the DPF, and the exhaust temperature (T3) at the rear of the DPF detected at the present time, respectively, and “vehicle speed ” is the detected vehicle speed at the present time, “D” is the exhaust gas temperature threshold, and 100 ° C is applied among the set range of about 90 to 100 ° C, and “E” is the vehicle speed threshold. It is set to approximately 0 km/h or 1 km/h.

A first set temperature (C), which is the initial temperature of the exhaust gas, a second set temperature (D) compared to the exhaust gas temperature (T1/T2/T3), and a constant speed (E) compared to the vehicle speed. can

As a result, the controller 60 sets the exhaust gas reduction device activation preparation state when the exhaust gas temperature of 100° C. or higher and the vehicle speed of 0 km/h or 1 km/h are both satisfied, and then proceeds to the burner operation condition determination step of S40. enter

Subsequently, the controller 60 determines the operating conditions of the burner in S40 at the exhaust gas temperature T3, and then raises the exhaust gas temperature at which the exhaust gas reduction device 1 cannot be activated during driving to the combustion flame of the burner 40. allow you to give At this time, the exhaust temperature T3 of the information of the data input unit 60-1 in FIG. 2 is read to confirm the rear end temperature of the DPF inside the exhaust pipe.

The controller 60 of the present invention applies the T3 exhaust temperature as the burner operation temperature. The reason why T3, the temperature at the end of the DPF, is selected as the monitoring point is that currently, the DPF control logic and the SCR control logic are operated by independent controllers, and the temperature at which the activation of the catalyst temperature of the DPF and the catalyst of the SCR can be activated only with the temperature at the end of the DPF. By accurately finding and applying the range and burner operating time (running time after ignition), it is possible to control the activation of the catalyst temperature of DPF and SCR, which is only possible with an integrated controller. To this end, the temperature condition for operating the burner is important.

Burner operating temperature condition: Exhaust gas temperature control value (T3) < F

Here, the "exhaust gas temperature control value" is the exhaust temperature (T3) detected at the time of activation of the exhaust gas reduction device required for the performance of the DPF (10A) and the selective reduction catalyst (SCR), and "F" is the temperature at the rear end of the DPF. As the upper limit threshold, 400℃ is applied out of the set range of about 350~400℃.

As a result, the controller 60 enters the burner operation steps of S50 to S60 when the exhaust gas temperature of 400° C. or less is satisfied. In this case, the controller 60 applies T5 and T6 as the exhaust gas temperature increase variables at the same temperature condition as T3 or slightly increased or decreased temperature conditions, so that the catalyst activation temperature reached by the exhaust gas temperature increase can be more precisely controlled.

Finally, the controller 60 performs the burner operation of S50 to S60 in the burner operating step of S50 and the burner flame sustaining step of S60.

For example, the burner operation (S50) performs fuel injection along with ignition of the igniter.

Referring to FIG. 2, the controller 60 puts the burner 40 in a combustion state in front of the DPF 10A inside the exhaust pipe by igniter ignition and fuel supply (or HC) through the output of the burner operation signal (a). The resulting combustion flame of the burner 40 can quickly raise the exhaust gas temperature to 200° C. or higher at the front end of the DPF 10A. In this case, the burner operation signal (a) may be output as an ON/OFF switch signal or PWM (Pulse Width Modulation) DUTY.

For example, in the burner flame sustain (S60), the controller 60 controls the operation of the burner 40 under a timer condition in which a time limit is applied to the output of the burner operation signal (a).

Timer (shutdown) condition: heating time > G

or Exhaust gas temperature control value (T3) > H

Here, the “heating time” is the burner operation time checked by the timer, and “G” is the cumulative threshold of the timer count, and 800 sec is applied out of the set range of about 750 to 800 sec.

In addition, “H” is the DPF rear end temperature upper limit threshold (Treshold), and the fourth set temperature (H) is the target temperature, and 400 ° C is applied among the set range of 350 to 400 ° C.

As a result, the controller 60 stops the operation of the burner 40 by stopping ignition of the igniter and stopping fuel supply when the heating time is 800 sec or more or the exhaust temperature (T3) is 400 ° C or more, thereby controlling burner operation (S50 to S60) quit

Meanwhile, referring to FIG. 2 , the controller 60 may provide the NOx content of the NOx sensor 50 to the Dosing Control Unit (DCU) after the burner operation (S50 to S60) is completed so that urea injection control is performed. This is because the combustion flame of the burner 40 raises the exhaust gas temperature to 200° C. or higher and activates the NOx sensor 50 quickly, so that the NOx content is accurately detected.

As described above, the method for activating the exhaust gas reduction device using the exhaust gas temperature increase implemented in the vehicle exhaust gas reduction device 1 according to the present embodiment is one of an error code, battery voltage, and exhaust pressure when the engine is started (IG On). The abnormality is detected as vehicle condition information, and after engine start (IG On), at least one of the exhaust temperature before/after burner (T0/T1), exhaust temperature before/after DPF (T2/T3), and vehicle speed is detected as driving information. , The combustion flame of the burner 40 through the ignition of the igniter and the supply of fuel so that the exhaust gas temperature is raised according to the upper limit threshold range of the exhaust temperature (T3) at the rear end of the DPF and the exhaust gas is discharged for a certain period of time (G ) or by heating to the target exhaust gas temperature (H), the temperature of the exhaust gas can be rapidly raised to 200° C. or more, and the nitrogen oxide (NOx) reduction performance of the exhaust gas can be improved.

1: vehicle exhaust gas reduction device
3: exhaust pipe
10A : DPF (Diesel Particulate Filter)
20: exhaust pressure sensor
30: temperature sensor
30a: burner front temperature sensor
30A: Temperature sensor at the end of the burner
30B: DPF shear temperature sensor
30C: DPF downstream temperature sensor
40: burner
50: NOx sensor
60: controller
60-1: Data input unit

Claims (8)

In the exhaust gas reduction device activation method using the exhaust gas temperature rise passing through the DPF where the burner is located at the front end,
After starting the vehicle (IG On), checking the vehicle condition by error code, battery voltage and exhaust pressure (S10),
Checking the temperature of the exhaust temperature To of the front end of the burner 40 and the first set temperature C (S20);
When the exhaust temperature To at the front of the burner 40 is smaller than the first set temperature C,
3 points of the exhaust temperature (T1) at the rear of the burner, the exhaust temperature (T2) at the front of the DPF, the exhaust temperature (T3) at the rear of the DPF, and the second set temperature (D) Temperature check step (S30),
When the exhaust temperature of the three points is less than the second set temperature (D) and the vehicle speed is greater than the predetermined speed,
Checking whether the exhaust temperature (T3) at the rear end of the DPF is within a certain range (S40);
If the exhaust temperature (T3) at the rear end of the DPF is less than the third set temperature (F), the igniter ignition and fuel injection control step (S50) and
By counting the progress time from the igniter ignition and fuel injection control step, when the predetermined time (G) is 800 sec or more or the exhaust temperature (T3) at the rear of the DPF is 400 ° C or more, which is the target temperature (H), the burner is operated A method for activating an exhaust gas reduction device using an exhaust gas temperature increase, characterized in that the end.
The method of claim 1,
The vehicle state is an exhaust gas reduction device activation method using an exhaust gas temperature increase, characterized in that no error code, battery voltage greater than a certain voltage and exhaust pressure greater than a certain pressure.
The method according to claim 2, when the vehicle condition is not satisfied,
A method of activating an exhaust gas reduction device using an exhaust gas temperature increase, characterized in that switching to the step (S10-1) of checking the vehicle state again after the waiting time (X) has elapsed.
The method of claim 1,
The first set temperature (C) is an exhaust gas reduction device activation method using an exhaust gas temperature increase, characterized in that 40 ℃.
The method of claim 1,
The second set temperature (D) is 100 ℃, the exhaust gas reduction device activation method using the exhaust gas temperature rise, characterized in that the constant speed is 1km / h.
The method of claim 1,
A method for activating an exhaust gas reduction device using an exhaust gas temperature increase, characterized in that the predetermined range for the exhaust temperature (T3) at the rear of the DPF is less than 400 ° C.
delete An exhaust gas reduction controller to which the exhaust gas reduction device activation method using the exhaust gas temperature increase according to any one of claims 1 to 6 is applied.

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