KR101755906B1 - Diesel Particulate Filter System Control Method and Vehicle thereby - Google Patents

Abstract

The DPF system 50 of the present invention detects whether the DPF temperature is excessive during automatic regeneration of a DPF (Diesel Particulate Filter) 51 that collects particulate matter contained in the exhaust gas discharged from the engine 10 A controller 40 for preventing the formation of a DPF abnormal regeneration condition due to excessive DPF temperature by introducing a compressed gas into the DPF 51 by shutting off the fuel at the end of cylinder compression stroke and opening the exhaust valve of the DPF temperature oversampling engine 10 The unstable regeneration of the DPF 51 is prevented even in the DTO when the vehicle 100 is stopped or the DTO when the pedal depression amount is 0% (acceleration pedal) at the time of automatic regeneration of the DPF 51, The cooling effect of the DPF 51 due to the compressed load associated with the brake implements possible features without increasing engine Idle RPM or boosting overrun conditions.

Description

TECHNICAL FIELD The present invention relates to a control method for a DPF system,

The present invention relates to automatic regeneration of a DPF (Diesel Particulate Filter), and more particularly, to a control method of a DPF system for preventing uncontrolled burning of a DPF (Diesel Particulate Filter) by an engine brake operation and a vehicle to which the DPF system is controlled.

In general, the DPF system can capture particulate matter in the exhaust gas of a diesel engine by removing the soot trapped in the DPF for a certain distance or time.

Also, in the DPF system, the regeneration process of burning the soot captured inside the DPF changes the engine condition so that regeneration may occur when the regeneration entry condition is satisfied while the vehicle is running, in addition to a manual mode in which the soot is burned by the driver operation in the vehicle stop state Automatic re-burning of soot is also possible

Particularly, the automatic regeneration is controlled by an ECU (Electronic Control Unit), and the ECU is capable of generating regeneration commands in consideration of vehicle mileage / soot collecting state / operation time, exhaust gas flow rate and DOC Catalyst), the post injection or HCI (Hydro Carbon Injection) injection amount determination is carried out so that the optimum combustion can take place. Thus, the soot captured in the DPF is efficiently burned.

Therefore, the DPF system is advantageous in that the process of collecting and regenerating soot is repeated by burning soot (soot) captured inside the DPF for a certain distance or time by burning using an after-engine injection or a separate fuel injection device . Particularly, the DPF system has become more important in recent years in order to meet the emission regulation of the flow channel 6, which is enhanced compared to the flow channel 5.

Korean Patent Laid-Open Publication No. 10-2007-0090633 (September 06, 2007)

However, automatic regeneration is accompanied by uncontrolled burning due to changes in vehicle driving conditions.

Examples of the abnormal regeneration include DTI (Drop to Idle), which causes a sudden decrease in the exhaust gas flow rate while dropping to an engine idle during stoppage of the vehicle during regeneration, and simultaneously raises the internal temperature of the DPF due to a reduction in cooling effect, There is DTO (Drop to Overrun) which increases the internal temperature of the DPF by increasing or decreasing the RPM (revolution per minute) or increasing the oxygen supply even though it is 0%. Furthermore, unsteady regeneration conditions such as DTI, DTO or DTO + DTI hybrid conditions are frequent occurrences during vehicle operation.

In particular, when problems such as overcrowding, HC (Hydro Carbon) slip, etc. are combined with changes in vehicle driving conditions, the inside of the DPF can not be controlled only by the engine condition, The DPF cracks and PM leaks, and the like.

In view of the above, it is an object of the present invention to improve the air flow rate for the DPF cooling effect by increasing the engine idle RPM or boosting the overrun condition by operating the engine brake at the time of abnormal control of the DPF (Diesel Particulate Filter) And a vehicle to which the DPF system is applied.

According to an aspect of the present invention, there is provided a method of controlling a DPF system, the method comprising: (A) burning a soot of a DPF (Diesel Particulate Filter) trapped in particulate matter contained in exhaust gas discharged from an engine; A DPF automatic regeneration step in which the post-fuel injection control is performed by the controller to the exhaust pipe; (B) stopping the post-fuel injection when the temperature of the DPF exceeds the DPF temperature due to an increase in the internal temperature of the DPF, introducing the compressed air into the DPF at the end of the cylinder compression stroke of the engine and closing the exhaust valve, And a DPF abnormality regeneration condition which is controlled by a controller to eliminate the phenomenon of excess of the DPF temperature by a developing unit.

In a preferred embodiment, the DPF automatic regeneration step includes regeneration command generation in consideration of vehicle mileage, soot collecting state, and operation time, exhaust gas flow rate flowing through the exhaust pipe according to vehicle driving conditions, and front and rear ends of a DOC (Diesel Oxidation Catalyst) Considering the temperature, the post-fuel injection is controlled so that combustion occurs in the post-fuel injection.

In a preferred embodiment, the step of resolving the DPF abnormal regeneration condition comprises the steps of: (B-1) checking whether the engine RPM of the engine is lowered to the engine idle or the engine RPM is maintained or increased; (B-2) When the engine idle drop of the engine RPM or the maintenance or increase of the engine RPM is compared with the target temperature set for optimal regeneration of the DPF, the exhaust gas temperature of the exhaust pipe is checked as an abnormal regeneration condition step; (B-3) after the post-fuel injection stop and the supply of the compressed fresh material are performed with the abnormal regeneration condition being satisfied, the exhaust gas temperature and the target temperature are recompiled and checked as a normal regeneration return condition; (B-4) a step of stopping supply of the compressed generator and restarting the post-fuel injection by satisfying the normal regeneration return condition and continuing automatic regeneration of the DPF; (B-5) the automatic regeneration of the DPF is performed until the regeneration of the DPF is completed.

As a preferred embodiment, the engine idle drop of the engine RPM is DTI (Drop to Idle) due to the vehicle stop, and the maintenance or increase of the engine RPM is performed by DTO (Drop to Overrun.

As a preferred embodiment, the target temperature for the abnormal regeneration condition determination may be determined when the target temperature of 120 to 125% is smaller than the DPF rear end temperature of the DPF, or when a target temperature of 108% Diesel Oxidation Catalyst), the abnormal regeneration condition is established.

In a preferred embodiment, the target temperature for determining the normal regeneration return condition is a temperature at which the target temperature of 115% is greater than the DPF rear end temperature of the DPF, or a target temperature of 103% Oxidation Catalyst) is determined to be the normal regeneration return condition.

As a preferred embodiment, the checking of the abnormal regeneration condition is not stopped when the automatic regeneration of the DPF is continued.

In a preferred embodiment, the compressed generator is generated by operation of an engine brake, and the engine brake is an exhaust brake such as a Jake brake.

In order to accomplish the above object, the present invention provides a DPF system for exhausting soot of DPF (Diesel Particulate Filter), which collects particulate matter contained in exhaust gas discharged from an engine, into an exhaust pipe A DPF automatic regeneration step in which the post-fuel injection control is performed, a post-fuel injection is stopped when the DPF temperature is increased due to an increase in the internal temperature of the DPF, And a controller for performing a DPF abnormal regeneration condition resolution step of controlling the DPF temperature to flow into the DPF and controlling the DPF temperature to be overcome by the compressed generator.

In a preferred embodiment, the controller is an engine ECU (Electronic Control Unit).

In order to accomplish the above object, the present invention provides a vehicle in which a soot of a DPF (Diesel Particulate Filter), which collects particulate matters contained in exhaust gas discharged from an engine, The DPF automatic regeneration step in which the post injection control is performed, the post fuel injection is stopped when the DPF temperature is increased due to the internal temperature rise of the DPF, the fuel compressed by the fuel cut- And performing a DPF abnormal regeneration condition resolution step in which the DPF abnormal temperature regeneration condition is controlled so that the phenomenon of excess of the DPF temperature is eliminated by the compressed generator; A DPF system controlled by the controller; And an exhaust brake type engine brake for generating the compressed air.

As a preferred embodiment, the DPF system is applied to commercial vehicles.

The present invention realizes the following advantages and effects by preventing the abnormal regeneration of the DPF, which may occur during the automatic regeneration, by the engine brake operation.

First, it can be implemented with a simple control logic change with a technique using compressed air generated by operation of a compression relief type engine brake (for example, an exhaust brake such as a Jake brake) which is installed without additional hardware configuration. Secondly, it is possible to control over-temperature due to DPF unsteady regeneration which may occur in various field conditions, thereby improving the DPF temperature over-regeneration problem during regeneration. Third, it is possible to improve DPF reliability and quality reduction due to PM leakage through improvement of DPF overheating problem during regeneration. Fourth, the abnormal reproduction of DPF due to DTI (Drop to Idle), which can occur when a heavy truck is stopped at a signal waiting state during a certain time operation after entering DPF regeneration in an inclined road like a slope road, is prevented.

2 is a configuration diagram of a DPF system applied to a vehicle according to the present invention, FIG. 3 is an automatic regeneration operation state of a DPF system applied to a vehicle according to the present invention, and FIG. 4 is a performance example of the DPF system according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which illustrate exemplary embodiments of the present invention. The present invention is not limited to these embodiments.

FIG. 1 shows a flowchart of a DPF system control method according to the present invention. As shown in the figure, in the DPF system control method, when a exhaust brake such as a Jake brake, which is one kind of engine brake, is operated, the compressed air to the DPF side is introduced by the fuel cutoff and exhaust valve opening at the end of each cylinder compression stroke, The present invention is characterized in that abnormal reproduction is prevented from occurring until the DPF reproduction is completed during the automatic reproduction.

2 shows a configuration of a DPF system applied to a vehicle according to the present invention. As shown, the vehicle 100 includes a DPF (Diesel Particulate Filter) system 50, which includes a damping-type engine 10, a fuel system 20, an exhaust system 30, And is controlled by the controller 40.

Specifically, the compression-relieving engine 10 serves as a braking function for decelerating the engine RPM due to pumping loss during compression / expansion of the engine brake, and at the same time, the compressed generator is discharged to the exhaust pipe, The internal temperature of the DPF is lowered. The engine 10 is a diesel engine, and the engine brake is an exhaust brake such as a jake brake. The fuel system 20 includes a fuel tank 21, a fuel pump 23 for pumping diesel fuel in the fuel tank 21, and a fuel filter 25 for filtering impurities in the diesel fuel. The exhaust system 30 includes an exhaust pipe 31 through which the exhaust gas of the engine 10 flows, a Diesel Oxidation Catalyst (DOC) 31 disposed in the exhaust gas flow path for collecting particulate matter (PM) (33). The controller 40 loads the DPF automatic regeneration control of the DPF system 50 into the basic logic together with the control of the engine 10, the fuel pump 23 and the engine brake. The DPF system 50 includes a DPF 51 that adsorbs PM to thereby burn soot, an injection unit 55 in which post-fuel injection is performed in conjunction with a metering unit 53 for fuel metering, a DOC 33, 57-2, and 57-3 that detect the temperatures of the temperature sensors 51-1, 51-2, and 51-3 and transmit them to the controller 40. [ In this case, the metering unit 53 and the injection unit 55 form a fuel injection device (HCI).

Therefore, the vehicle 100 is a commercial vehicle such as a heavy truck. However, the controller 40 detects the DTI state together with the detected values of the engine and the vehicle condition. When the vehicle 100 is in the DTO state when the vehicle 100 stops or when the pedal is depressed at 0% (acceleration pedal) And an abnormal condition canceling mode in which the engine brake operation of the engine 10 is linked to the automatic regeneration of the DPF 51 in accordance with the post-DPF temperature. Also, the controller 40 may be a dedicated controller of the DPF system 50, but it is preferable to apply an engine ECU (Electronic Control Unit).

Hereinafter, an embodiment of the DPF automatic regeneration method including the abnormal condition elimination mode will be described in detail with reference to FIG. 3 and FIG. The control object is the DPF 51 associated with the engine 10, the fuel pump 23 and the HCI. The control subject reads the detection values of the temperature sensors 57-1, 57-2, 57-3, And the controller 40 for detecting the condition of the DTO and the acceleration pedal answer input.

S10 is an automatic regeneration step of the DPF 51, which is performed according to the automatic regeneration procedure which is the basic logic of the controller 40. [ Therefore, the controller 40 generates a regeneration command in consideration of the vehicle mileage / soot collecting state / operation time, the exhaust gas flow rate and the temperature sensors 57-1 and 57-2 flowing through the exhaust pipe 31 according to the vehicle driving conditions, (Metering unit 53 and injection unit 55) so that optimum combustion can take place in consideration of the upstream / downstream temperatures of the DOC 53 detected by the upstream /

S20 is a step of determining whether or not the DPF 51 has been completely regenerated. In this case, if the regeneration has been completed, the controller 40 switches to S100 to determine that the automatic regeneration of the DPF has been completed, The abnormality condition canceling mode performed in S30 to S90 is switched to thereby eliminate the abnormal regeneration condition that may occur in the regeneration of the DPF 51. [

Specifically, the abnormal condition dissolution mode is performed as follows.

Step S30 is a step of judging the abnormal regeneration condition of the DPF 51 as the driving condition of the vehicle 100. [ To this end, the controller 40 checks the condition of DTI at the time of vehicle stop and DTO at the pedal depression amount 0% (accelerator pedal). Such a check may be made such that the generation of the DTI and the DTO at the time of automatic regeneration of the DPF during traveling of the vehicle 100 forms an internal abnormal regeneration condition of the DPF 51 so that the DPF 1 is automatically regenerated Can be prevented.

Step S40 is a step of judging the abnormal regeneration condition of the DPF 51 as the exhaust gas temperature flowing through the exhaust pipe 31. [ To this end, the controller 40 compares the detected values of the temperature sensors 57-2 and 57-3 with the target temperature to determine whether the DOC downstream temperature overshoot or the DPF downstream temperature is excessive. For example, the DOC downstream temperature overshoot is determined to be 108% of the target temperature and the DOC downstream temperature is determined to be 125% of the target temperature by determining that the DPF downstream temperature exceeds 125% of the target temperature. . Here, ">" is an inequality indicating the magnitude relationship between the two values. In the case where the DOC rear end temperature is 108% of the target temperature or the DPF rear end temperature is 120 to 125% The target temperature is the exhaust gas temperature flowing through the exhaust pipe 31 and is the value of the DOC downstream temperature set for optimal regeneration of the DPF 51. [

As a result of the check in S40, if either of the DOC rear end temperature overshoot or the DPF rear end temperature excess is not satisfied, the automatic regeneration of the DPF 1 is continued by returning to S10, and if any one of the conditions is satisfied .

Step S50 is a step of switching the abnormal regeneration condition to a normal regeneration condition. To this end, the controller 40 controls the exhaust brake of the engine 10 Forced stopping of post-injection by HCI while forced operation. At this time, the exhaust brake is operated in the state of the vehicle stop at the DTI time and the state of the pedal 0% at the DTO time, so that the operation state of the vehicle 100 is hardly affected.

Step S60 is a stage in which DPF regeneration is continued in a state where the internal temperature of the DPF 51 is lowered due to fresh air inflow. In this step, as a result of the exhaust brake operation, the engine 10 is discharged to the exhaust pipe 31 by the fuel cut-off at the end of each cylinder compression stroke and the exhaust valve opening, and the compressed air flowing through the exhaust pipe 31 is discharged to the DOC 33 to flow into the DPF 51 so that the internal temperature of the DPF 51 falls and the DPF 51 undergoes automatic regeneration under normal regeneration conditions due to the internal temperature drop. The results of this step are illustrated in FIG. As shown in the figure, the internal temperature of the DPF 1 rises with the lapse of time after the DTI occurrence time point but it is found that the internal temperature of the DPF 1 is lower than that of the exhaust brake operation (a) as a result of the exhaust brake operation (A).

S70 is a step of determining whether or not the abnormal playback condition is canceled and checking the normal playback return condition. To this end, the controller 40 compares the detected values of the temperature sensors 57-2 and 57-3 with the target temperature to determine whether the DOC downstream temperature overshoot or the DPF downstream temperature is excessive. For example, the DOC rear end temperature overshoot is determined as 103% of the DOC rear end temperature < 103% of the target temperature, and the DPF rear end temperature is determined to be 115% of the target temperature & do. Here, "" is an inequality indicating the magnitude relationship between the two values. In the case where the DOC rear end temperature <103% of the target temperature or the DPF rear end temperature <115% of the target temperature is less than the target temperature, it means.

As a result of S70, if the DOC tail end temperature <103% of the target temperature or the post-DPF temperature <115% of the target temperature is not satisfied, the controller 40 feeds back to S40 or S50, To S80.

Step S80 is a step of completely canceling the abnormal reproduction condition and fixing the normal reproduction return condition. Therefore, the controller 40 switches to stop the exhaust brake and restart the post-injection of HCI, and by continuing the automatic regeneration of the DPF 51, the remaining Soot regeneration is performed in a state where the DOC rear end temperature and the DPF rear end temperature are within the controllable range Ensure smoothness.

In particular, the controller 40 confirms whether the abnormal regeneration has recurred until the regeneration of the DPF 1 is completed by checking the temperature of the downstream end of the DOC and the downstream temperature of the DPF and feeding back to the step S40 or feeding back to the step S50. ) Is completed, the step S100 is further performed.

As described above, in the DPF system 50 according to the present embodiment, when the automatic regeneration of the DPF (Diesel Particulate Filter) 51 in which the particulate matter contained in the exhaust gas discharged from the engine 10 is captured, DPF temperature is detected, and a compressed air is introduced into the DPF 51 by the fuel cut-off and exhaust valve opening at the end of cylinder compression stroke of the DPF temperature overdrive engine 10, and thereby the DPF abnormal regeneration condition The controller 40 prevents the DPF 51 from being automatically regenerated when the vehicle 100 is stopped or when the pedal depression amount is 0% ), And in particular, the cooling effect of the DPF 51 due to the compressed load associated with the engine brake is realized without increasing the engine Idle RPM or increasing the boost of the overrun condition.

10: Compression type engine 20: Fuel system
21: fuel tank 23: fuel pump
25: fuel filter 30: exhaust system
31: exhaust pipe 33: DOC (Diesel Oxidation Catalyst)
40: controller 50: DPF (Diesel Particulate Filter) system
51: DPF 53: metering unit
55: injection unit 57-1, 57-2, 57-3: temperature sensor
100: vehicle

Claims (13)

A DPF system in which a controller performs automatic post-fuel injection control to the exhaust pipe so as to burn soot of a DPF (Diesel Particulate Filter) that collects particulate matter contained in exhaust gas discharged from an engine, In the control method,
The controller performs a DPF abnormal regeneration condition elimination step with the vehicle stop or accelerator pedal depression amount as a vehicle driving condition after the fuel post injection control;
The step of resolving the DPF abnormal regeneration condition includes the steps of checking whether the engine RPM of the engine is lowered to engine idle or the engine RPM is maintained or increased; When the engine idle drop of the engine RPM or the maintenance or increase of the engine RPM is compared with the target temperature set for optimal regeneration of the DPF and the abnormal regeneration condition is checked; Fuel injection stop is performed as the exhaust brake is operated with the abnormality regeneration condition being satisfied and the compressed air is introduced into the DPF by the fuel cutoff and the exhaust valve opening at the end of the cylinder compression stroke of the engine, After the gas temperature and the target temperature are recompiled, the normal regeneration return condition is checked; Stopping the supply of the compressed generator by stopping the operation of the exhaust brake due to the normal regeneration return condition and restarting the post-fuel injection so that the automatic regeneration of the DPF is continued; The automatic regeneration of the DPF is continued until the regeneration of the DPF is completed
Wherein the DPF system control method comprises:
[2] The automatic regeneration method of claim 1, wherein the automatic regeneration of the DPF includes: generating a regeneration command that considers the mileage of the vehicle, the soot collecting state, and the operating time, a flow rate of the exhaust gas flowing through the exhaust pipe according to the vehicle driving condition, And the post-fuel injection is controlled so that combustion takes place in the post-fuel injection.
delete delete The DPF of claim 1, wherein the target temperature for determining the abnormal regeneration condition is a target temperature of 120 to 125% when the target temperature is less than a DPF rear end temperature of the DPF, or a target temperature of 108% Diesel Oxidation Catalyst (Diesel Oxidation Catalyst), the abnormal regeneration condition is established.
The DPF of claim 1, wherein the target temperature for determining the normal regeneration return condition is a target temperature of 115% when the target temperature is greater than a DPF rear end temperature of the DPF, or a target temperature of 103% Wherein the normal regeneration return condition is established when the temperature is greater than the DOC downstream temperature of the oxidation catalyst.
The DPF system control method according to claim 1, wherein the checking of the abnormal regeneration condition is not stopped when the automatic regeneration of the DPF is continued.
delete delete A DPF system comprising a controller for performing a DPF system control method according to any one of claims 1, 2, and 5 to 7.
The DPF system according to claim 10, wherein the controller is an engine ECU (Electronic Control Unit)
A vehicle comprising a DPF system controlled by a DPF system control method according to any one of claims 1, 2, and 5 to 7.
13. The vehicle of claim 12, wherein the DPF system is applied to a commercial vehicle.

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