KR20160084087A - Apparatus for monitoring condition of dpf for vehicle - Google Patents

Abstract

The present invention comprises: an electronic control unit (ECU) calculating particulate matter (PM) emission quantity of an engine exit; a PM sensor detecting PM emission quantity of a rear end of a diesel particulate filter (DPF); and a sensor controller monitoring the condition of the DPF by using the PM emission quantity of the rear end of the DPF with respect to the PM emission quantity of the engine exit.

Description

[0001] APPARATUS FOR MONITORING CONDITION OF DPF FOR VEHICLE [0002]

The present invention relates to an apparatus and a method for monitoring a DPF state of a vehicle, and more particularly, to an apparatus and method for monitoring the state of a DPF based on a change amount of a PM emission amount after a DPF with respect to a PM emission amount at an engine exit, And more particularly, to a DPF state monitoring apparatus and method.

Air pollution in diesel vehicles is mainly caused by nitrogen oxides (NOx) and particulate matter (PM) called particulate matter. Since DPF (Diesel Particulate Filter) can satisfactorily satisfy exhaust regulations by removing most PM of engine, it is recognized that the normal operation of DPF is important for PM emission. As a result, the installation of DPF for removing PM in diesel vehicles has been recognized as a necessity in order to cope with exhaust emission regulation.

In recent years, as the OBD (On Board Diagnosis) regulatory value has been strengthened, monitoring of the post-treatment system (DPF system) has been strengthened, and it is difficult to cope with the present system (differential pressure sensor, system modeling) in the future.

Conventionally, a sensor is installed at the front and rear of the DPF, and the state of the DPF is monitored by determining whether the sensor value exceeds a predetermined threshold value.

However, according to the prior art, since the sensor signal is compared with a predetermined threshold value to determine whether or not the DPF is damaged, there is a limit to the use of the sensor according to the DPF damage degree. In consideration of the OBD restriction value, It is very difficult to determine whether or not the DPF is damaged.

Background Art [0002] The background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2005-0112707 (2005.12.01) 'System and Method for Diagnosing Magnetic Faults of Diesel Particulate Filter'.

It is an object of the present invention to provide an apparatus and method for monitoring a DPF state of a vehicle that monitors a state of a DPF based on a change amount of a PM emission amount after a DPF with respect to a PM emission amount at an engine exit .

It is another object of the present invention to provide an apparatus and method for monitoring the state of a DPF of a vehicle that can accurately determine damage or abnormal operation of the DPF and more suitably cope with the OBD regulation value to be enhanced.

An apparatus for monitoring a DPF state of a vehicle according to an aspect of the present invention includes: an ECU (Electronic Control Unit) for calculating a PM emission amount at an engine exit; A PM (Particulate Matter) sensor for detecting the PM emission amount at the downstream of DPF (Diesel Particulate Filter); And a sensor controller for monitoring whether or not the DPF is damaged by using the PM emission amount at the downstream of the DPF with respect to the PM emission amount at the engine outlet.

In the present invention, the sensor controller collects the PM emission amount at the engine outlet and the PM emission amount at the rear end of the DPF for each cycle of the PM sensor, and calculates the variation amount of the PM emission amount at the engine outlet and the variation amount of the PM emission amount at the downstream end of the DPF The state of the DPF is determined on the basis of a variation amount of the PM emission amount at the engine outlet and a variation amount of the PM emission amount at the rear end of the DPF.

In the present invention, when the PM emission amount in the current cycle of the engine exit is equal to or greater than the PM emission amount in the previous cycle, the sensor controller determines that the PM emission amount in the previous cycle after the DPF is larger than the PM emission amount in the current cycle The DPF is determined to be in a normal state.

In the present invention, when the PM emission amount in the current cycle of the engine exit is equal to or greater than the PM emission amount in the previous cycle, the sensor controller determines that the PM emission amount in the previous cycle after the DPF is smaller than the PM emission amount in the current cycle The state of the DPF is determined as a damaged state.

In the present invention, if the PM emission amount in the current cycle of the engine exit is smaller than the PM emission amount in the previous cycle, and the PM emission amount in the current cycle after the DPF is greater than or equal to the PM emission amount in the previous cycle, It is determined that the DPF is in a normal state.

In the present invention, when the PM emission amount in the current cycle of the engine exit is smaller than the PM emission amount in the previous cycle, if the PM emission amount in the current cycle after the DPF is smaller than the PM emission amount in the previous cycle, Is judged as a broken state.

According to an aspect of the present invention, there is provided a method for monitoring a DPF state of a vehicle, the method comprising: collecting a PM emission amount at an engine exit and a PM emission amount at a rear end of a DPF for each sensing cycle of the PM sensor; Calculating a variation amount of the PM emission amount at the engine outlet and a variation amount of the PM emission amount at the downstream end of the DPF, respectively; And monitoring the state of the DPF based on a variation amount of the PM emission amount at the engine outlet and a variation amount of the PM emission amount at the downstream end of the DPF.

In the present invention, the step of determining the state of the DPF may include determining whether the PM emission amount in the previous cycle of the DPF is greater than or equal to the PM emission amount in the previous cycle, And if it is greater than or equal to the PM emission amount, the state of the DPF is determined as a normal state.

In the present invention, the step of determining the state of the DPF may include determining whether the PM emission amount in the previous cycle of the DPF is greater than or equal to the PM emission amount in the previous cycle, And the state of the DPF is determined as a damaged state when the amount of PM is smaller than the amount of PM discharged.

In the present invention, the step of determining the state of the DPF may include determining whether the PM emission amount in the current cycle after the DPF is smaller than the PM emission amount in the previous cycle, when the PM emission amount in the current cycle of the engine exit is smaller than the PM emission amount in the previous cycle The DPF is determined to be in a normal state.

In the present invention, the step of determining the state of the DPF may include determining whether the PM emission amount in the current cycle after the DPF is smaller than the PM emission amount in the previous cycle, when the PM emission amount in the current cycle of the engine exit is smaller than the PM emission amount in the previous cycle The state of the DPF is determined as a damaged state.

The present invention judges whether or not the DPF is broken based on the amount of change in the amount of PM discharged after the DPF with respect to the amount of PM discharged from the engine exit, so that it is possible to accurately determine the damage or abnormal operation of the DPF and more suitably cope with the OBD .

1 is a block diagram of an apparatus for monitoring a DPF state of a vehicle according to an embodiment of the present invention.
2 is a conceptual diagram illustrating a DPF structure according to an embodiment of the present invention.
FIG. 3 is a diagram showing the crack level and the normal state of each of the DPFs according to an embodiment of the present invention.
4 is a diagram illustrating signal characteristics of a sensor signal according to an embodiment of the present invention.
5 is a flowchart of a method of monitoring a DPF state of a vehicle according to an embodiment of the present invention.

Hereinafter, an apparatus and method for monitoring a DPF state of a vehicle according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. Further, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the user, the intention or custom of the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

FIG. 1 is a block diagram of an apparatus for monitoring the state of a DPF of a vehicle according to an embodiment of the present invention. FIG. 2 is a conceptual view of a DPF structure according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a signal characteristic of a sensor signal according to an embodiment of the present invention. FIG.

Referring to FIG. 1, an apparatus for monitoring a DPF state of a vehicle according to an embodiment of the present invention includes a DPF 30, an ECU 40, a sensor controller 50, and a PM sensor 52.

A DPF (Diesel Particulate Filter) 30 removes most of PM (Particulate Matter) of the engine 10. The process of suppressing exhaust of soot through the DPF 30 includes a series of regeneration processes of collecting soot and removing the collected soot by oxidation reaction when a certain amount of PM is collected therein. In this case, the regeneration mode holds the PM in the DPF 30, and after a certain period of time, the PM is oxidized and regenerated in the catalyst.

Referring to FIG. 2, the DPF 30 has a DPF pore formed therein to collect PM, and is regenerated by oxidizing the PM in the catalyst in the regeneration mode.

Referring to FIG. 3, in the steady-state DPF 30, when the PM discharge amount of the engine 10 is large, the PM is accumulated on the DPF pores or the DPF web quickly, so that the PM discharge is relatively small at the rear end .

On the other hand, if the amount of PM discharged from the engine 10 is large in the damaged DPF 30, such as cracks larger than the DPF pores, the PM discharge amount of the DPF 30 is also increased depending on the PM discharge amount of the engine 10 Which increases as the degree of damage increases.

In other words, the DPF 30 is less likely to be damaged if it is determined only by the quantitative limit value without reflecting the operation characteristics due to the breakage of the DPF 30, so that the DPF 30, as in SAMPLE A in Fig. 3, It is very difficult to judge whether it is. SAMPLE A is a filter that is substantially in a broken state (damage filter), although the DPF (normal filter) in a steady state and its PM emissions are very similar. The DPF 30 is substantially difficult to determine whether the DPF 30 is damaged by a simple limit value as described above. The sensor controller 50 determines whether the DPF 30 is damaged based on the amount of change in the amount of PM discharged at the downstream of the DPF 30 with respect to the amount of PM discharged from the outlet of the engine 10. This will be described later.

On the other hand, an ECU (Electronic Control Unit) 40 calculates a PM emission amount discharged from the engine 10 through the first exhaust pipe 21, and transmits the calculated PM emission amount to the sensor controller 50. The first exhaust pipe 21 is connected to the engine 10 at one side and the DPF 30 at the other side to deliver PM discharged from the engine 10 to the DPF 30.

The PM sensor 52 senses the amount of PM discharged from the DPF 30 through the second exhaust pipe 22. The PM sensor 52 repeats a certain cycle as shown in FIG. 3. The PM sensor 52 performs a warm-up process, a regeneration process for removing PMs collected in a previous cycle, a stabilization period of a sensor signal ), A sensing period, and a PM signal measurement (Measuring). Therefore, the PM sensor 52 repeatedly performs the above-described cycle.

3, S _MR is the limit signal value for reproduction, S _Ms is the signal amplitude at the beginning of the signal period measurement, and S _Mf is the signal amplitude at the end of the signal period measurement. For reference, the signal sizes of S _MR , S _Ms, and S _Mf are S _MR ~R _ref <S _Ms <S _Mf to R _fail . Here, R _ref is a predetermined reference value that can be determined as a normal sensor signal when the PM is sensed after the regeneration period, and R _fail is a state in which PM remains even after a normal regeneration process, and the PM sensor 52 Is a failure reference value that can be determined as an abnormal sensor signal.

Also, T _S is a signal period between S _Ms and S _Mf , and T _S <T _M is set for determining the DPF failure, and the minimum value of S _Mf (S _Mfm ) is set in T _M for determination of DPF failure. _S is set in the range of S and S _{Mfm Ms} doedoe set relative to the S and S _{Mfm Ms.}

The sensor controller 50 determines whether the DPF 30 is damaged or not by using the amount of PM discharged from the DPF 30 downstream of the outlet of the engine 10 to determine whether the DPF 30 is damaged or abnormal, do.

More specifically, the sensor controller 50 collects the PM emission amount at the outlet of the engine 10 and the PM emission amount at the rear end of the DPF 30 for each sensing cycle of the PM sensor 52.

The sensor controller 50 calculates the amount of change in the PM emission amount at the outlet of the engine 10 using the PM emission amount at the outlet of the engine 10 and calculates the amount of PM emission at the downstream end of the DPF 30 Calculate the amount of change in emissions. The amount of change in the PM emission amount at the outlet of the engine 10 and the amount of change in the PM emission amount at the downstream end of the DPF 30 are calculated, The state of the DPF 30 is determined based on the amount of change in the PM emission amount.

In this case, when the PM discharge amount of the current cycle at the outlet of the engine 10 is equal to or greater than the PM discharge amount in the previous cycle, the sensor controller 50 determines that the PM discharge amount in the previous cycle after the DPF 30 is the PM The state of the DPF 30 is determined to be a normal state, and if the PM discharge amount in the previous cycle after the DPF 30 is smaller than the PM discharge amount in the current cycle, the state of the DPF 30 is regarded as a broken state .

On the other hand, when the PM emission amount of the current cycle at the outlet of the engine 10 is smaller than the PM emission amount in the previous cycle, the sensor controller 50 determines that the PM emission amount of the current cycle after the DPF 30 is larger than the PM emission amount of the previous cycle The DPF 30 is determined to be in a normal state and the DPF 30 is determined to be in a damaged state if the PM discharge amount of the current cycle at the downstream end of the DPF 30 is smaller than the PM discharge amount of the previous cycle.

Hereinafter, a method for monitoring a DPF state of a vehicle according to an embodiment of the present invention will be described in detail with reference to FIG.

5 is a flowchart of a method of monitoring a DPF state of a vehicle according to an embodiment of the present invention.

Referring to FIG. 5, the sensor controller 50 warms up the PM sensor 52 (S10).

The sensor controller 50 then determines whether the DPF 30 is being reproduced (S20). If it is determined that the DPF 30 is currently being reproduced, the sensor controller 50 waits for the DPF 30 to perform the reproduction process, Return.

On the other hand, when the regeneration of the DPF 30 is completed, the sensor controller 50 controls the PM sensor 52 to perform the regeneration mode (S30).

In this case, the sensor controller 50 determines whether the sensor signal input from the PM sensor 52 is less than a preset reference reference value R _ref (S32). If the sensor signal is determined as a predetermined reference reference value R _ref ), It is determined whether or not the sensor signal exceeds the error reference value R _fail (S34).

If the sensor signal is less than the error reference value R _{fail as a} result of the determination in step S34, the sensor controller 50 returns to step S30. On the other hand, if the sensor signal exceeds the error reference value R _fail , 50 determines that an error has occurred in the PM sensor 52 and warns the sensor error through a cluster (not shown) (S36). Accordingly, the driver can recognize the PM sensor error and handle the PM sensor 52 error. Here, the reason that the sensor signal exceeds the error reference value R _fail is that the PM sensor 52 detects that the PM is relatively collected in the DPF 30 despite the fact that the DPF performs the oxidation process , It can be judged as a separate PM sensor error.

On the other hand, if it is determined in step S32 that the sensor signal is less than the predetermined reference value R _ref , the sensor controller 50 collects the sensor signal from the PM sensor 52 during the current cycle of T _M , Thereby calculating the PM emission amount S _{PM .n} discharged from the DPF 30 through the second exhaust pipe 22 during T _S (S42). Here, PM emission (S _{.n PM)} discharged through the second exhaust pipe 22 from the DPF (30) for T _S can be calculated through the (S -S _{Ms Mf)} / T _S.

In addition, the sensor controller 50 collects the PM level discharged from the engine 10 through the first exhaust pipe 21 during the current cycle of T _s from the ECU 40 (S50), integrates the collected PM level (PM _eng.n ) discharged from the engine 10 through the first exhaust pipe 21 during T _S (S52).

Following the sensor controller 50 first from the engine 10 during the T _S of the previous cycle from the PM emission amount is discharged through the first exhaust pipe 21 from the engine 10 during the T _S of the current cycle (PM _{eng .n)} subtracting the PM emissions (PM _{eng .n-1)} that is discharged through the exhaust pipe 21, and the subtraction (PM _{eng eng} -PM _{.n .n-1)} a value of a predetermined set value, for example 0 or more (S60).

On the other hand, when the judgment result in the step (S60) subtracting (PM _{eng eng} -PM _{.n .n-1)} a value is greater than or equal to 0, the sensor controller 50 by a T _S during the PM sensor 52 of the previous cycle Whether the value obtained by subtracting the PM emission amount S _{PM .n} detected by the PM sensor 52 during the current cycle T _S from the sensed PM emission amount S _{PM .n-1} is equal to or greater than a set value 0 (S70).

If the value of the difference (S _{PM .n-1} -S _{PM .n} ) is 0 or more as a result of the determination in step S70, the sensor controller 50 determines the state of the DPF 30 as a normal state (S80) If the value of the difference (S _{PM .n-1} -S _{PM .n} ) is less than 0, the sensor controller 50 judges the state of the DPF 30 as a damaged state (S 100).

On the other hand, when the judgment result of subtracting (PM _{eng eng} -PM _{.n .n-1)} a value in the step (S60) is less than zero, the sensor controller 50 T _S for the PM sensor 52 of the current cycle, the PM emission amount detected by (S _{.n PM)} in the sensed by the previous cycle T _S for PM sensor (52) PM emission subtracted by subtracting the _{(S PM .n-1) (} S PM .n -S PM. _n-1 ) is greater than or equal to 0 (S90).

If the value of the difference (S _{PM .n} -S _{PM .n-1} ) is 0 or more as a result of the determination in step S90, the sensor controller 50 determines the DPF 30 as a normal state (S80) (S _{PM .n} -S _{PM .n-1} ) is less than 0, it is determined that the DPF 30 is in a broken state (S 100).

As described above, the present embodiment determines whether the DPF 30 is broken or not based on the amount of change in the PM emission amount at the downstream of the DPF 30 with respect to the PM emission amount at the outlet of the engine 10, and accurately determines the breakage or abnormal operation of the DPF 30 And to better accommodate the enhanced OBD regulated values.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, I will understand. Accordingly, the true scope of the present invention should be determined by the following claims.

10: Engine
21: First exhaust pipe
22: Second exhaust pipe
30: DPF
40: ECU
50: Sensor controller
52: PM sensor

Claims (11)

An ECU (Electronic Control Unit) for calculating the PM emission amount at the engine outlet;
A PM (Particulate Matter) sensor for detecting the PM emission amount at the downstream of DPF (Diesel Particulate Filter); And
And a sensor controller for monitoring the state of the DPF using a PM emission amount at a downstream end of the DPF with respect to a PM emission amount at the engine outlet.
2. The apparatus of claim 1, wherein the sensor controller
The PM emission amount at the engine outlet and the PM emission amount at the downstream end of the DPF are collected for each cycle of the PM sensor to calculate a variation amount of the PM emission amount at the engine outlet and a variation amount of the PM emission amount at the downstream end of the DPF, And the state of the DPF is determined on the basis of a change amount of the amount of emission and a change amount of the amount of PM emission after the DPF.
3. The apparatus of claim 2, wherein the sensor controller
If the PM emission amount in the current cycle of the engine exit is equal to or greater than the PM emission amount in the previous cycle and the PM emission amount in the previous cycle after the DPF is equal to or greater than the PM emission amount in the current cycle, The DPF state monitoring apparatus comprising:
3. The apparatus of claim 2, wherein the sensor controller
If the PM emission amount in the current cycle of the engine exit is equal to or greater than the PM emission amount in the previous cycle and the PM emission amount in the previous cycle after the DPF is smaller than the PM emission amount in the current cycle, The DPF state monitoring apparatus comprising:
3. The apparatus of claim 2, wherein the sensor controller
If the PM emission amount in the current cycle of the engine exit is less than the PM emission amount in the previous cycle and the PM emission amount in the current cycle after the DPF is equal to or greater than the PM emission amount in the previous cycle, The DPF state monitoring apparatus comprising:
3. The apparatus of claim 2, wherein the sensor controller
If the PM emission amount in the current cycle of the engine exit is smaller than the PM emission amount in the previous cycle and the PM emission amount in the current cycle after the DPF is smaller than the PM emission amount in the previous cycle, Wherein the DPF state monitoring device is configured to monitor the DPF state of the vehicle.
Collecting a PM emission amount at an engine exit and a PM emission amount at a post-DPF end by a sensing cycle of the PM sensor;
Calculating a variation amount of the PM emission amount at the engine outlet and a variation amount of the PM emission amount at the downstream end of the DPF, respectively; And
Monitoring the state of the DPF based on a variation amount of the PM emission amount at the engine outlet and a variation amount of the PM emission amount at the rear end of the DPF.
8. The method of claim 7, wherein determining the state of the DPF comprises:
If the PM emission amount in the current cycle of the engine exit is equal to or greater than the PM emission amount in the previous cycle and the PM emission amount in the previous cycle after the DPF is equal to or greater than the PM emission amount in the current cycle, The method comprising the steps of:
8. The method of claim 7, wherein determining the state of the DPF comprises:
If the PM emission amount in the current cycle of the engine exit is equal to or greater than the PM emission amount in the previous cycle and the PM emission amount in the previous cycle after the DPF is smaller than the PM emission amount in the current cycle, And determining the DPF state of the vehicle.
8. The method of claim 7, wherein determining the state of the DPF comprises:
If the PM emission amount in the current cycle of the engine exit is less than the PM emission amount in the previous cycle and the PM emission amount in the current cycle after the DPF is equal to or greater than the PM emission amount in the previous cycle, And the DPF state of the vehicle.
8. The method of claim 7, wherein determining the state of the DPF comprises:
If the PM emission amount in the current cycle of the engine exit is smaller than the PM emission amount in the previous cycle and the PM emission amount in the current cycle after the DPF is smaller than the PM emission amount in the previous cycle, Wherein the DPF monitoring unit monitors the DPF status of the vehicle.

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