KR101484223B1 - Regeneration system and method for diesel particulate filter - Google Patents

Abstract

The present invention relates to an apparatus and a method to regenerate a diesel particulate filter (DPF) and, more specifically, to an apparatus and a method to regenerate a DPF, which prevent catalytic deactivation by protecting a catalyst mounted on the upstream of a DPF from being exposed to high temperatures during the process of regenerating the DPF through fuel post injection. The method comprises: a step of determining regeneration timing of a DPF by detecting operation information including a differential pressure between the upstream and the downstream of the DPF, a driving distance, and an operation time; a step of regenerating the DPF by increasing the temperature of an exhaust gas to high temperatures through fuel post injection; a step of calculating a temperature difference by detecting the temperature of the upstream of a catalyst, and the upstream of the DPF when regeneration of the DPF starts; and a step of preventing the catalyst from being exposed to high temperatures by adjusting the amount of fuel post injection in accordance to a temperature difference and the gradient of the temperature difference.

Description

TECHNICAL FIELD [0001] The present invention relates to a diesel particulate filter regenerating apparatus,

The present invention relates to an apparatus and a method for regenerating a diesel particulate filter (DPF), and more particularly, to a method and apparatus for regenerating a diesel particulate filter (DPF) The present invention relates to a diesel particulate filter regeneration apparatus and method for preventing catalyst deterioration by protecting a catalyst to be mounted from being exposed to high temperatures.

Diesel vehicles are equipped with engines that provide lean burning for the purpose of improving fuel efficiency.

(DOC) or a nitrogen oxide storage catalyst (LNT) is mounted on a predetermined position of the exhaust manifold, and the diesel oxidation catalyst (DOC) or the nitrogen oxide storage catalyst A diesel particulate filter (DPF) is installed at the rear end of the LNT to provide a stable emission.

The diesel oxidation catalyst (DOC) purifies carbon monoxide (CO) and hydrocarbons (HC) contained in the exhaust gas by oxidizing and discharges the exhaust gas.

The nitrogen oxide storage catalyst (LNT) occludes and stores nitrogen oxides (NOx) generated by lean burning of the engine and reduces nitrogen oxides (NOx) to nitrogen (N2) by a reducing action.

The diesel particulate filter (DPF) physically collects particulate matter (PM) such as soot contained in the exhaust gas and filters particulate matter (PM) so as not to be discharged into the atmosphere.

The diesel particulate filter (DPF) is periodically regenerated in accordance with the trapped amount of particulate matter such as soot, traveling distance, running time, fuel consumption amount, and differential pressure between the front and rear.

Regeneration of the diesel particulate filter (DPF) raises the temperature of the exhaust gas to about 600 ° C to 700 ° C or higher through the post-fuel injection to burn particulate matter such as soot collected.

In order to increase the amount of the post-injection fuel to efficiently burn particulate matter (PM) such as soot, a diesel oxidation catalyst (DOC) or a nitrogen oxide storage catalyst (LNT) mounted on the front end of the diesel particulate filter ) Is exposed to high temperature to lose the activity of the catalyst.

Therefore, precise temperature control is required in the process of regenerating the diesel particulate filter (DPF).

4 is a view showing a temperature control for a conventional diesel particulate filter (DPF) regeneration.

Referring to FIG. 4, a target temperature (for example, 600 to 700 ° C.) is set based on the front end temperature for regenerating the diesel particulate filter (DPF), and the post-fuel injection control is executed.

At this time, if the front end temperature of the diesel particulate filter (DPF) is detected and the post-injection fuel amount is increased if the target temperature is lower than the target temperature, the post-injection fuel amount is decreased when the target temperature is exceeded, PI (proportional integral) control is executed so as to follow.

The temperature control in the above-described manner changes the shear temperature of the diesel particulate filter (DPF) according to the acceleration / deceleration of the vehicle or the change of the vehicle condition. At this time, when the excessive fuel is injected afterwards, Can be severely deteriorated.

Further, when regenerating a diesel particulate filter (DPF), a method of adjusting the amount of post-injection fuel using the temperature difference between the upstream and downstream ends is used for more precise temperature control.

FIGS. 5 and 6 are graphs for evaluating the forced regeneration of the conventional diesel particulate filter.

Referring to FIG. 5, when the diesel particulate filter is forcibly regenerated under the general running conditions of the third speed / 50 KPH, the temperature distribution shown in Table 1 below is detected.

LNT Shear LNT Bed LNT Outlet DPF Inlet Maximum temperature (℃) 542 810 733 645

Referring to FIG. 6, when the diesel particulate filter is forcibly regenerated in the NEDC mode, the temperature distribution shown in Table 2 is detected.

LNT Shear LNT Bed LNT Outlet DPF Inlet Maximum temperature (℃) 465 947 819 696

As can be seen from Tables 1 and 2, when a diesel particulate filter is forcibly regenerated, a bed of a nitrogen oxide storage catalyst (LNT) installed at the front end may be exposed to a maximum of 810 ° C or 947 ° C to cause serious deterioration .

Accordingly, in order to prevent the deterioration of the diesel oxidation catalyst (DOC) or the nitrogen oxide storage catalyst (LNT) mounted on the upstream side of the diesel particulate filter (DPF) when controlling the regeneration of the diesel particulate filter (DPF) Control is required.

Japanese Patent Application Laid-Open No. 10-2011-0024252 (Mar. Open Patent Publication No. 10-2007-0090633 (2007.09.06.)

The object of the present invention is to provide a diesel particulate filter (DPF) which prevents the catalyst mounted on the front end of a diesel particulate filter (DPF) from being exposed to high temperatures during regeneration of the diesel particulate filter through post- And to provide a diesel particulate filter regenerating apparatus and method for preventing the particulate filter.

A feature according to an embodiment of the present invention is an engine for providing lean burn; A catalyst for purifying harmful substances contained in the exhaust gas discharged from the engine; A diesel particulate filter mounted on a rear end of the catalyst to collect the soot contained in the exhaust gas; A lambda sensor that detects the amount of oxygen contained in the exhaust gas and provides the state of the air-fuel ratio of the engine to the control unit; and a control unit that controls the regeneration of the diesel particulate filter by controlling the amount of post-injection fuel. A first temperature sensor mounted on a front end of the catalyst to detect a temperature of the front end of the catalyst and provide the detected temperature to the control unit; And a second temperature sensor mounted on a front end of the diesel particulate filter to detect the temperature of the front end of the diesel particulate filter and provide the detected temperature to the control unit, wherein when the regeneration of the diesel particulate filter is performed, There is provided a diesel particulate filter regenerating apparatus for calculating a slope of a temperature difference and a temperature difference between a front end of a catalyst and a diesel particulate filter and adjusting a post injection fuel amount according to a temperature difference and a slope of a temperature difference to prevent a catalyst from being exposed to a high temperature.

The control unit may adjust the post-injection fuel amount by performing an increase correction to the basic injection amount by a predetermined amount when the front end temperature of the diesel particulate filter is lowered in the calculation of the temperature difference between the front end of the catalyst and the front end of the diesel particulate filter.

Wherein the controller corrects the basic injection amount by a predetermined amount when the temperature difference between the front end of the catalyst and the diesel particulate filter exceeds a set reference temperature and the slope of the temperature difference exceeds a set reference slope, Can be adjusted.

According to another aspect of the present invention, there is provided a method for controlling a diesel particulate filter, the method comprising: detecting driving information including a differential pressure, a traveling distance, and a driving time of a diesel particulate filter according to operation of the diesel particulate filter; And regenerating the diesel particulate filter by raising the temperature of the exhaust gas to a high temperature by the post-fuel injection control when the diesel particulate filter is regenerated; Detecting the temperature of the catalyst front end and the temperature of the front end of the diesel particulate filter when the regeneration of the diesel particulate filter starts, calculating a temperature difference, and calculating a slope of the temperature difference; And adjusting the post-injection fuel amount according to the calculated temperature difference and the temperature difference to prevent the catalyst from being exposed at a high temperature.

When the shearing temperature of the diesel particulate filter is lowered in the calculation of the temperature difference between the front end of the catalyst and the front end of the diesel particulate filter, the amount of the post-injection fuel can be increased by a certain amount.

If the temperature difference between the front ends of the catalyst and the diesel particulate filter exceeds the set reference temperature and the slope of the temperature difference exceeds the set reference time exceeding the set reference slope, the post- have.

As described above, the present invention has the effect of enhancing the purification efficiency of the exhaust gas by preventing deterioration of the catalyst mounted on the front end in the regeneration of the diesel particulate filter.

Further, it provides durability of the catalyst mounted on the front end of the diesel particulate filter, satisfying the exhaust gas regulation, and providing reliability in the operation of the diesel vehicle.

1 is a view schematically showing a diesel particulate filter regenerating apparatus according to an embodiment of the present invention.
2 is a flowchart schematically illustrating a procedure of regenerating a diesel particulate filter according to an embodiment of the present invention.
3 is a view showing the temperature measurement results of the respective parts in the process of regenerating the diesel particulate filter.
4 is a view showing a temperature control for regenerating a conventional diesel particulate filter.
FIGS. 5 and 6 are graphs for evaluating the forced regeneration of the conventional diesel particulate filter.

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 limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are given the same reference numerals throughout the specification.

In addition, since the components shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to those shown in the drawings.

1 is a view schematically showing a diesel particulate filter regenerating apparatus according to an embodiment of the present invention.

Referring to FIG. 1, an embodiment of the present invention includes an engine 10, a catalyst 20, a diesel particulate filter 30, a controller 40, a lambda sensor 51, a first temperature sensor 52, And a temperature sensor 53.

The engine 10 is a power source and generates power by burning a mixture ratio of air and fuel under lean conditions under the control of the control unit 40.

The catalyst 20 is mounted on an exhaust manifold 15 of the engine 10 to purify harmful substances such as CO, HC and NOx contained in the exhaust gas by an oxidizing and reducing action.

The catalyst 20 may be applied as a diesel oxidation catalyst (DOC) or a nitrogen oxide storage catalyst (LNT).

The diesel particulate filter 30 physically collects particulate matter (PM) such as soot contained in the exhaust gas and prevents it from being discharged to the atmosphere.

The diesel particulate filter 30 is periodically regenerated to burn particulate matter PM collected according to the mileage calculated from the collection amount, particulars of the particulate matter (PM) determined as the differential pressure between the upstream and downstream sides, and the travel time .

The regeneration of the diesel particulate filter 30 is carried out at a high temperature of approximately 600 to 700 ° C.

The lambda sensor 51 detects the amount of oxygen contained in the exhaust gas discharged from the engine 10 and provides the control unit 40 with the air-fuel ratio state information of the combustion of the engine 10 as an electrical signal.

The first temperature sensor 52 is mounted on the front end of the catalyst 20 and detects the temperature of the front end of the catalyst 20, that is, the temperature of the exhaust gas supplied to the catalyst 20 and provides the detected temperature to the control unit 40 as an electrical signal .

The second temperature sensor 53 is mounted on the front end of the diesel particulate filter 30 to detect the temperature of the exhaust gas supplied to the diesel particulate filter 30, To the control unit (40).

The control unit 40 determines the regeneration point of the diesel particulate filter 30 in accordance with the mileage calculated by the amount of particulate matter PM determined as the pressure difference between the front and rear of the diesel particulate filter 30, .

When the regeneration point of the diesel particulate filter 30 is determined, the control unit 40 raises the temperature of the exhaust gas to a high temperature of a predetermined temperature of about 600 to 700 ° C. by the post-fuel injection control, Thereby controlling the regeneration of burning the particulate matter PM.

The control unit 40 controls the temperature rise of the exhaust gas by applying at least one of the control of the fuel amount injected to the engine 10, the intake air amount adjustment, or the fuel injection control at the rear end of the exhaust manifold.

The control unit 40 detects the front end temperature T1 of the catalyst 20 from the first temperature sensor 52 mounted on the front end of the catalyst 20 when the regeneration of the diesel particulate filter 30 is started, (T2) of the diesel particulate filter (20) from the second temperature sensor (53) mounted on the front end of the filter (30).

The controller 40 calculates the temperature difference T2-T1 between the front end temperature T1 of the catalyst 20 and the front end temperature T2 of the diesel particulate filter 30.

The controller 40 differentiates the temperature difference T2-T1 between the front end temperature T1 of the catalyst 20 and the front end temperature T2 of the diesel particulate filter 30 by time to obtain a temperature difference T2- DELTA (T2-T1) / DELTA t) of the target value [Delta] (T2-T1)].

The controller 40 controls the temperature of the diesel particulate filter 30 in accordance with the temperature difference T2-T1 between the catalyst 20 and the front end of the diesel particulate filter 30 and the slope? T2-T1 /? T of the temperature difference T2- And corrects the injected fuel amount to stably maintain the temperature of the exhaust gas discharged from the engine 10.

When the front end temperature T2 of the diesel particulate filter 30 is lowered in the calculation of the temperature difference T2-T1 between the catalyst 20 and the front end of the diesel particulate filter 30, ) To adjust the post-injection fuel amount.

The control unit 40 determines whether the temperature difference T2-T1 between the catalyst 20 and the front end of the diesel particulate filter 30 exceeds the set reference temperature and the slope of the temperature difference T2- ) / [Delta] t) exceeds a reference time set in a state in which the reference slope exceeds the set reference slope, the post injection fuel amount is adjusted by performing a weight correction on the basic injection amount by a predetermined amount (e).

Therefore, the temperature of the exhaust gas discharged from the engine 10 can be stably maintained, and the catalyst 20 mounted on the front end of the diesel particulate filter 30 can be prevented from being exposed to high temperatures and being deteriorated.

The control unit 40 normally controls the fuel injection amount when the regeneration of the diesel particulate filter 30 according to the above procedure is completed.

The procedure for regenerating the exhaust gas purifying apparatus of the vehicle according to the embodiment of the present invention having the functions described above will be described with reference to FIG. 2 as follows.

When the diesel vehicle to which the present invention is applied is operated, the control unit 40 includes mileage calculated based on the amount of particulate matter (PM) trapped by the diesel particulate filter 30, the mileage, The operation information is detected (S101) and it is determined whether the regeneration condition (regeneration point) of the diesel particulate filter 30 is satisfied (S102).

If the regeneration condition (regeneration time) of the diesel particulate filter 30 is satisfied in step S103, the controller 40 raises the temperature of the exhaust gas to a predetermined temperature of about 600 to 700 DEG C by the post-fuel injection control, The regeneration of burning particulate matter (PM) collected in the filter 30 is started (S103).

The controller 40 controls the temperature of the exhaust gas from the first temperature sensor 52 mounted on the upstream side of the catalyst 20 when the regeneration of the diesel particulate filter 30 is initiated by a catalyst composed of a diesel oxidation catalyst DOC or a nitrogen oxide storage catalyst 20 is detected (S104).

The control unit 40 detects the front end temperature T2 of the diesel particulate filter 20 from the second temperature sensor 53 mounted on the front end of the diesel particulate filter 30 in step S105.

The control unit 40 calculates the temperature difference T2-T1 between the front end temperature T1 of the catalyst 20 detected at S104 and the front end temperature T2 of the diesel particulate filter 30 detected at S105, (T2-T1) /? T) of the temperature difference (T2-T1) by differentiating the temperature difference (T2-T1) by the time.

The controller 40 determines whether or not the slope Δ (T2-T1) / Δt of the temperature difference (T2-T1) and the temperature difference (T2-T1) between the catalyst 20 and the front end of the diesel particulate filter 30, , The post-injection fuel amount is corrected, and the temperature of the front end of the catalyst 20 is stably maintained in the engine 10 (S107).

When the front end temperature T2 of the diesel particulate filter 30 is lowered in the calculation of the temperature difference T2-T1 between the catalyst 20 and the front end of the diesel particulate filter 30, ) To adjust the post-injection fuel amount.

The control unit 40 determines whether the temperature difference T2-T1 between the catalyst 20 and the front end of the diesel particulate filter 30 exceeds the set reference temperature and the slope of the temperature difference T2- ) / [Delta] t) exceeds a reference time set in a state in which the reference slope exceeds the set reference slope, the post injection fuel amount is adjusted by performing a weight correction on the basic injection amount by a predetermined amount (e).

3, when the shear temperature of the diesel oxidation catalyst (DOC) and the temperature difference between the front end of the diesel particulate filter (DPF) and the gradient of the temperature difference ("A region") increase, The bed temperature of the catalyst (DOC) is increased, and the deterioration of the diesel oxidation catalyst (DOC) is expected.

At this time, the post injection fuel amount is adjusted by reducing the basic injection amount by a predetermined amount (e) to prevent the temperature of the exhaust gas from rising.

Therefore, the temperature of the exhaust gas discharged from the engine 10 can be stably maintained, and the catalyst 20 mounted on the front end of the diesel particulate filter 30 can be prevented from being exposed to high temperatures and being deteriorated.

The control unit 40 determines whether the regeneration of the diesel particulate filter 30 according to the above procedure has been completed (S108). If the regeneration is completed, the control unit 40 normally executes the fuel injection amount control (S109).

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 will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

10: engine 20: catalyst
30: Diesel particulate filter 40:

Claims (7)

An engine providing lean burn;
A catalyst for purifying harmful substances contained in the exhaust gas discharged from the engine;
A diesel particulate filter mounted on a rear end of the catalyst to collect the soot contained in the exhaust gas;
A control unit for periodically controlling the regeneration of the diesel particulate filter by controlling the amount of post-injection fuel;
Lt; / RTI >
A lambda sensor that detects the amount of oxygen contained in the exhaust gas and provides the state of the air-fuel ratio of the engine to the control unit;
A first temperature sensor mounted on a front end of the catalyst to detect a temperature of the front end of the catalyst and provide the detected temperature to the control unit;
A second temperature sensor mounted on a front end of the diesel particulate filter to detect a leading end temperature of the diesel particulate filter and provide the detected temperature to the control unit;
/ RTI >
When the regeneration of the diesel particulate filter is performed, the control unit calculates the slope of the temperature difference and the temperature difference between the front end of the catalyst and the diesel particulate filter from the information of the first and second temperature sensors, and adjusts the post-injection fuel amount according to the slope of the temperature difference and the temperature difference The catalyst is prevented from being exposed to high temperatures,
Wherein the controller adjusts the post-injection fuel amount by performing an increase correction to the basic injection amount by a predetermined amount when the front end temperature of the diesel particulate filter is lowered in calculating the temperature difference between the front end of the catalyst and the front end of the diesel particulate filter. delete The method according to claim 1,
Wherein the controller corrects the basic injection amount by a predetermined amount when the temperature difference between the front end of the catalyst and the diesel particulate filter exceeds a set reference temperature and the slope of the temperature difference exceeds a set reference slope, Diesel particulate filter regulating device to adjust. A step of determining whether the diesel particulate filter is regenerated by detecting the operation information including the differential pressure, the travel distance, and the operating time of the diesel particulate filter according to the operation of the diesel vehicle;
And regenerating the diesel particulate filter by raising the temperature of the exhaust gas to a high temperature by the post-fuel injection control when the diesel particulate filter is regenerated;
Detecting the temperature of the catalyst front end and the temperature of the front end of the diesel particulate filter when the regeneration of the diesel particulate filter starts, calculating a temperature difference, and calculating a slope of the temperature difference;
Adjusting a post-injection fuel amount according to a slope of the calculated temperature difference and a temperature difference to prevent the catalyst from being exposed at a high temperature;
/ RTI >
Wherein the post-injection fuel amount is increased by a predetermined amount when the shearing temperature of the diesel particulate filter is lowered in calculating the temperature difference between the catalyst and the front end of the diesel particulate filter. delete 5. The method of claim 4,
When the temperature difference between the front ends of the catalyst and the diesel particulate filter exceeds the set reference temperature and the slope of the temperature difference exceeds the set reference time exceeding the set reference slope, the diesel particulate filter prevents the high temperature exposure of the catalyst by adjusting the amount of post- How to regenerate the soot filter. Lean burn engines;
A catalyst for purifying harmful substances contained in the engine exhaust gas;
A diesel particulate filter mounted on the rear end of the catalyst to collect the soot;
A control unit for controlling the periodic regeneration of the diesel particulate filter;
/ RTI >
Wherein the control unit is operated by a set program to execute any one of the methods of claims 4 and 6 to prevent high temperature exposure of the catalyst during the regeneration of the diesel particulate filter.

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