KR101896756B1 - A method for correcting dpf differential-pressure sensor - Google Patents

Abstract

The present invention relates to a DPF differential pressure sensor correction method and apparatus. A DPF differential pressure sensor correction method according to an embodiment of the present invention includes deriving a reference sensor value for a current exhaust flow rate from a pre-stored exhaust flow rate-reference sensor value table (SlOO); Determining whether a difference between the reference sensor value and a measured sensor value of the DPF differential pressure sensor exceeds a preset reference error (S200); If the difference between the reference sensor value and the measurement sensor value exceeds the preset reference error, deriving a new reference sensor value (S300); And changing the reference sensor value of the previously stored reference sensor value-differential pressure table to the new reference sensor value (S400). According to the present invention, it is possible to improve the accuracy of the differential pressure derived from the DPF differential pressure sensor, thereby precisely diagnosing whether the DPF regeneration timing and the DPF regeneration have occurred or not. In addition, since a separate PM sensor can be omitted, the cost can be reduced.

Description

[0001] The present invention relates to a DPF differential pressure sensor correcting method,

The present invention relates to a DPF differential pressure sensor correction method and apparatus, and more particularly, to a DPF differential pressure sensor correction method and apparatus capable of improving accuracy of a differential pressure derived from a DPF differential pressure sensor.

In general, the demand for diesel engines is continuously increasing because it is possible to operate at low fuel consumption, high output and high load. However, air pollution caused by diesel vehicles is attributed to NOx and particulate matter (PM) contained in the exhaust gas, which is responsible for about 40% of total air pollution. In order to cope with this problem, each country is strengthening the exhaust gas regulations of diesel engines.

To cope with such exhaust gas emission regulations for diesel engines, a separate post-treatment system has been applied. Currently, DOC (Diesel Oxidation Catalyst), DPF (Diesel Particulate Filter), LNT NOx Trap) and SCR (Selective Catalytic Reduction) using Urea. Particularly, DOC (Diesel Oxidation Catalyst) and DPF (Diesel Particulate Filter) are arranged side by side.

The DOC serves to increase the exhaust temperature on the upstream side of the DPF when regenerating the DPF. That is, when the fuel as the reducing agent is supplied to the DOC, the oxidation reaction of the fuel occurs inside the DOC, thereby increasing the exhaust temperature on the upstream side of the DPF. The DPF adsorbs and deposits PMs (Particulate Matters) coming from the diesel engine, so that PMs (Particulate Matters) are not included in the final exhaust gas.

However, if the accumulation amount of the PM trapped in the DPF increases, the DPF becomes clogged, and thus the back pressure of the exhaust increases and the output of the diesel engine decreases. Therefore, the oxidation reaction as described above is induced in the DOC to raise the temperature of the exhaust gas, and the PM is burned and removed by the exhaust gas at an increased temperature, which is called regeneration of the DPF.

It is important to measure the amount of PM trapped in the DPF in determining the point in time when the regeneration of the DPF is required. The DPF differential pressure sensor is installed at the front end and the rear end of the DPF, and it is possible to calculate the amount of PM deposited in the DPF by measuring the pressure difference between the front end and the rear end of the DPF. Therefore, when the DPF differential pressure sensor acting as the above-described sensor deteriorates and an error occurs in the measured value, the amount of PM can not be accurately measured, so that the DPF regeneration can not be smoothly performed.

Conventionally, in order to solve the above problem, the output value of the DPF differential pressure sensor in the state where there is no exhaust flow in the exhaust pipe after stopping the engine is corrected to zero. However, the DPF differential pressure sensor is a device for measuring the differential pressure when there is a flow of exhaust gas in the exhaust pipe. In such a correction method, there is a problem that the error in operation of the DPF differential pressure sensor can not be precisely corrected.

Patent Registration No. 10-0903338 (Jun. 10, 2009)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for precisely correcting errors due to deterioration of a DPF differential pressure sensor.

A DPF differential pressure sensor correction method according to an embodiment of the present invention includes deriving a reference sensor value for a current exhaust flow rate from a pre-stored exhaust flow rate-reference sensor value table (SlOO); Determining whether a difference between the reference sensor value and a measured sensor value of the DPF differential pressure sensor exceeds a preset reference error (S200); If the difference between the reference sensor value and the measurement sensor value exceeds the preset reference error, deriving a new reference sensor value (S300); And changing the reference sensor value of the previously stored reference sensor value-differential pressure table to the new reference sensor value (S400).

The deriving step S300 is characterized by deriving a new reference sensor value according to the following equation.

The sum of the reference sensor value application ratio and the predetermined measurement sensor value application ratio is 1.

A DPF differential pressure sensor correction method according to another embodiment of the present invention includes deriving a reference sensor value for a measured current exhaust flow rate from a pre-stored exhaust flow rate-reference sensor value table (S100 '); Determining whether a difference between the reference sensor value and a measured sensor value of the DPF differential pressure sensor exceeds a preset reference error (S200 '); Deriving a correction coefficient when the difference between the reference sensor value and the measurement sensor value exceeds the preset reference error (S300 '); And deriving a correction sensor value corrected from the correction coefficient and the measurement sensor value (S400).

The step of deriving the correction coefficient (S300 ') derives the correction coefficient according to the following equation.

The sum of the reference sensor value application ratio and the predetermined measurement sensor value application ratio is 1.

Deriving the corrected measurement sensor value (S400 ') derives the corrected measurement sensor value according to the following equation.

A DPF differential pressure sensor correction method according to another embodiment of the present invention includes the steps of: (S10) determining whether DPF regeneration has ended; Determining whether the vehicle is traveling (S20); (S30) if the travel distance after the end of regeneration of the DPF is less than a predetermined first reference travel distance (A) when the vehicle is traveling; (S40) determining whether the exhaust flow rate is maintained constant when the travel distance after the regeneration of the DPF is less than a predetermined first reference travel distance; And correcting the DPF differential pressure sensor according to the DPF differential pressure sensor correction method according to any one of claims 1 to 6 when the exhaust flow rate is kept constant (S50).

The determining step S40 is characterized in that it is determined that the exhaust flow rate is maintained constant when the difference between the maximum value and the minimum value of the exhaust flow rate within a predetermined reference time is less than a preset reference error.

The DPF differential pressure sensor correction method may further include determining whether the vehicle is forcibly regenerating the vehicle if the vehicle is not running (S60).

The DPF differential pressure sensor correcting method includes the step (S70) of determining whether the post-correction running distance of the DPF differential pressure sensor exceeds a predetermined second reference running distance (B) when the vehicle is forcibly regenerating .

The DPF differential pressure sensor correction method may further include a step of performing the correction step S50 when the corrected travel distance of the DPF differential pressure sensor exceeds a predetermined second reference travel distance (B).

The DPF differential pressure sensor correction method is stored in the storage medium according to another embodiment of the present invention.

A DPF differential pressure sensor correcting apparatus according to another embodiment of the present invention includes the storage medium 100; An exhaust flow rate measuring unit 200 for measuring an exhaust flow rate of the vehicle; A DPF differential pressure sensor 300 mounted at the front end and the rear end of the DPF for measuring a difference between pressures at the front end and the rear end of the DPF; And an ECU (400) for correcting an error of the DPF differential pressure sensor (300) according to a DPF differential pressure sensor correction method stored in the storage medium (100) using the difference between the exhaust flow rate and the pressure at the front end and the rear end of the DPF, .

As described above, according to the present invention, it is possible to improve the accuracy of the differential pressure derived from the DPF differential pressure sensor, thereby accurately diagnosing whether the DPF regeneration timing and the DPF regeneration have occurred during regeneration.

In addition, since a separate PM sensor can be omitted, the cost can be reduced.

1 is a flowchart of a DPF differential pressure sensor correction method according to an embodiment of the present invention;
Fig. 2 is a view for explaining a reference sensor value-differential pressure graph corrected according to Fig. 1; Fig.
3 is a flowchart of a DPF differential pressure sensor correction method according to another embodiment of the present invention.
Fig. 4 is a diagram for explaining calculation of the corrected differential pressure according to the measurement sensor value corrected in the reference sensor value-differential pressure graph according to Fig. 3; Fig.
5 is a flowchart of a DPF differential pressure sensor correction method according to another embodiment of the present invention;
6 is a block diagram of a DPF differential pressure sensor correction device according to another embodiment of the present invention.

It is to be understood that the words or words used in the present specification and claims are not to be construed in a conventional or dictionary sense and that the inventor can properly define the concept of a term in order to describe its invention in the best way And should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a flowchart of a DPF differential pressure sensor correction method according to an embodiment of the present invention, and FIG. 2 is a view for explaining a reference sensor value-differential pressure graph corrected according to FIG. 1 and 2, the DPF differential pressure sensor correction method according to an embodiment of the present invention includes deriving a reference sensor value for a current exhaust flow amount from a pre-stored exhaust flow rate-reference sensor value table (S100 ); Determining whether a difference between the reference sensor value and a measured sensor value of the differential pressure sensor of the DPF exceeds a preset reference error (S200); If the difference between the reference sensor value and the measurement sensor value exceeds the preset reference error, deriving a new reference sensor value (S300); And changing the reference sensor value of the previously stored reference sensor value-differential pressure table to the new reference sensor value (S400).

In the deriving step S100, the reference sensor value for the current exhaust flow rate is derived from the pre-stored exhaust flow rate-reference sensor value table as illustrated in Table 1 below.

Exhaust flow rate (kg / h) 200 600 Reference sensor value (V) 2 4

For example, assuming that the current exhaust flow rate is 600 kg / h, the reference sensor value is derived as 4V.

In the determining step S200, it is determined whether the difference between the reference sensor value and the measured sensor value of the DPF differential pressure sensor exceeds a preset reference error. At this time, the predetermined reference error may be set differently according to the type of the DPF differential pressure sensor or the intention of the designer. That is, when the precision of the DPF differential pressure sensor is desired to be high, the reference error can be set small. If the difference between the reference sensor value and the measured sensor value of the DPF differential pressure sensor does not exceed the preset reference error, the DPF differential pressure sensor does not deteriorate, so the previous reference sensor value-differential pressure table is maintained See Table 2 to be described later).

For example, assuming that the reference error is 0.3 V and the measurement sensor value is 3.6 V, the difference between the reference sensor value and the measurement sensor value is 0.4 V. Therefore, since the reference error is exceeded, it can be determined that the DPF differential pressure sensor has deteriorated.

If the difference between the reference sensor value and the measurement sensor value exceeds the preset reference error, the new reference sensor value is derived according to the following equation (1).

At this time, the sum of the predetermined reference sensor value application ratio and the predetermined measurement sensor value application ratio should be 1, and the preset reference sensor value application ratio and the predetermined measurement sensor value application ratio may be different from the DPF differential pressure sensor type Or the designer's intention.

For example, when the predetermined reference sensor value application ratio is 0.5 and the predetermined measurement sensor value application ratio is 0.5, the new reference sensor value becomes 4V X 0.5 + 3.6V X 0.5 = 3.8V.

The changing step S400 is a step of changing the reference sensor value of the stored reference sensor value-differential pressure table to the new reference sensor value.

For example, supposing that a previously stored reference sensor value-differential pressure table is stored as shown in Table 2 below, the reference sensor value (4V) is changed to a new reference sensor value (3.8V) Stored reference sensor value-differential pressure table.

Reference sensor value (V) One 2 4 Differential pressure (kPa) 0 40 120

Reference sensor value (V) One 2 3.8 Differential pressure (kPa) 0 40 120

Accordingly, the characteristic curve of the reference sensor value-differential pressure also changes from FIG. 2 (a) to FIG. 2 (b). Thereafter, when the measured sensor value of the DPF differential pressure sensor corrected as described above is 3.8 V, the differential pressure is derived as 120 kPa. Therefore, it is possible to improve the accuracy of the differential pressure derived from the sensor by correcting the error caused by the deterioration of the DPF differential pressure sensor. Accordingly, it is possible to precisely diagnose whether or not the DPF regeneration timing and the DPF regeneration have occurred during regeneration. In addition, since a separate PM sensor can be omitted, the cost can be reduced.

FIG. 3 is a flowchart of a DPF differential pressure sensor correction method according to another embodiment of the present invention, and FIG. 4 illustrates calculation of a differential pressure corrected according to a measurement sensor value corrected in the reference sensor value- FIG. 3 and 4, the DPF differential pressure sensor correction method according to another embodiment of the present invention includes deriving a reference sensor value for the measured current exhaust flow rate from a pre-stored exhaust flow rate-reference sensor value table Step S100 '); Determining whether a difference between the reference sensor value and a measured sensor value of the differential pressure sensor of the DPF exceeds a preset reference error (S200 '); Deriving a correction coefficient when the difference between the reference sensor value and the measurement sensor value exceeds the preset reference error (S300 '); And deriving a correction sensor value corrected from the correction coefficient and the measurement sensor value (S400).

The deriving step S100` and the determining step S200` are the same as the DPF differential pressure sensor correction method of FIG.

If the difference between the reference sensor value and the measurement sensor value exceeds the predetermined reference error, deriving the correction coefficient is derived according to the following equation (2).

At this time, the sum of the predetermined reference sensor value application ratio and the predetermined measurement sensor value application ratio should be 1, and the preset reference sensor value application ratio and the predetermined measurement sensor value application ratio may be different from the DPF differential pressure sensor type Or the designer's intention.

For example, when the preset reference sensor value application ratio is 0.5 and the predetermined measurement sensor value application ratio is 0.5, the correction coefficient is 1 - (4V X 0.5 + 3.6V X 0.5) / 4V = about 0.05.

Deriving the corrected measurement sensor value (S400 ') derives the corrected measurement sensor value from the correction coefficient and the measurement sensor value according to the following equation (3).

For example, when the measurement sensor value is 3.6 V and the correction coefficient is 0.05, the corrected measurement sensor value is 3.78 V. The characteristic curve of the reference sensor value-differential pressure according to the reference sensor value-differential pressure table as shown in Table 2 is as shown in FIG. Therefore, when the measured sensor value in the deteriorated DPF differential pressure sensor is 3.6 V on the characteristic curve of the reference sensor value-differential pressure as described above, the differential pressure should be detected as 104 kPa. That is, a differential pressure (120 kPa) and an error of 16 kPa occur when the reference sensor value is 4 V in the DPF differential pressure sensor in a steady state. However, since the differential pressure according to the calibrated measuring sensor value (3.78 V) becomes 111.2 V, the error with the differential pressure (120 kPa) when the reference sensor value is 4 V in the steady state DPF differential pressure sensor is reduced to 8.8 kPa (b)). That is, it can be confirmed that the error of 9.2 kPa is eliminated by one correction.

Therefore, the present invention can improve the accuracy of the differential pressure derived from the sensor by correcting errors due to the deterioration of the DPF differential pressure sensor. Accordingly, it is possible to precisely diagnose whether or not the DPF regeneration timing and the DPF regeneration have occurred during regeneration. In addition, since a separate PM sensor can be omitted, the cost can be reduced.

5 is a flowchart of a DPF differential pressure sensor correction method according to another embodiment of the present invention. Referring to FIG. 5, the DPF differential pressure sensor correction method according to still another embodiment of the present invention includes: (S10) determining whether DPF regeneration has ended; Determining whether the vehicle is traveling (S20); (S30) if the travel distance after the end of regeneration of the DPF is less than a predetermined first reference travel distance (A) when the vehicle is traveling; (S40) determining whether the exhaust flow rate is maintained constant when the travel distance after the regeneration of the DPF is less than a predetermined first reference travel distance; And a step (S50) of correcting the DPF differential pressure sensor according to the DPF differential pressure sensor correction method when the exhaust flow rate is kept constant.

That is, after the end of the regeneration, the DPF differential pressure sensor is corrected if the condition that the vehicle is running and the exhaust flow rate is kept constant within a certain distance is satisfied. If the difference between the maximum value and the minimum value of the exhaust flow rate within a predetermined reference time is less than a preset reference error, the determining step S40 determines that the exhaust flow rate is maintained constant.

The predetermined first reference travel distance A, the predetermined reference time, and the predetermined reference error may be set differently according to the type of vehicle or the designer's intention.

The DPF differential pressure sensor correcting method includes: determining whether the vehicle is forcibly regenerating (S60) if the vehicle is not running; And a step (S70) of determining whether the corrected travel distance of the DPF differential pressure sensor exceeds a predetermined second reference travel distance (B) when the vehicle is forcibly regenerated, If the travel distance exceeds the predetermined second reference travel distance B, the step of correcting (S50) is performed.

That is, the DPF differential pressure sensor is corrected even when the vehicle is in a stopped state after forced regeneration, and the running distance after the immediately preceding correction is within a certain distance. At this time, the forcible regeneration means regeneration which is forcibly executed by an operation of the operator or the like when repairing the vehicle. Also, the predetermined reference travel distance B may be set differently depending on the type of vehicle or the designer's intention.

6 is a block diagram of a DPF differential pressure sensor correction apparatus according to another embodiment of the present invention. Referring to FIG. 6, the DPF differential pressure sensor correction device according to another embodiment of the present invention includes: a storage medium 100 storing the DPF differential pressure sensor correction method; An exhaust flow rate measuring unit 200 for measuring an exhaust flow rate of the vehicle; A DPF differential pressure sensor 300 mounted at the front end and the rear end of the DPF for measuring a difference between pressures at the front end and the rear end of the DPF; And an ECU (400) for correcting an error of the DPF differential pressure sensor (300) according to a DPF differential pressure sensor correction method stored in the storage medium (100) using the difference between the exhaust flow rate and the pressure at the front end and the rear end of the DPF, .

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory only and are not restrictive of the invention, as claimed, and will be fully understood by those of ordinary skill in the art. The present invention is not limited thereto. It will be apparent to those skilled in the art that various substitutions, modifications and variations are possible within the scope of the present invention, and it is obvious that those parts easily changeable by those skilled in the art are included in the scope of the present invention .

100 storage medium
200 Exhaust flow measuring unit
300 DPF differential pressure sensor
400 ECU

Claims (14)

delete delete delete delete delete delete delete Determining whether DPF (Diesel Particulate Filter) reproduction is completed (SlO);
Determining whether the vehicle is traveling (S20);
(S30) if the travel distance after the end of regeneration of the DPF is less than a predetermined first reference travel distance (A) when the vehicle is traveling;
Determining whether the exhaust flow rate is maintained constant if the travel distance after the regeneration of the DPF is less than a predetermined first reference travel distance (S40); And
(S100) of deriving a reference sensor value for the current exhaust flow rate from the pre-stored exhaust flow rate-reference sensor value table when the exhaust flow rate is kept constant, A step (S200) of determining whether a difference between the sensor values exceeds a predetermined reference error; and deriving a new reference sensor value when the difference between the reference sensor value and the measurement sensor value exceeds the predetermined reference error And a step (S400) of changing the reference sensor value of the pre-stored reference sensor value-differential pressure table to the new reference sensor value (S50) by correcting the DPF differential pressure sensor 300 according to the DPF differential pressure sensor correction method );
Wherein the DPF differential pressure sensor correction method comprises: 9. The method of claim 8,
Wherein the determining step S40 determines that the exhaust flow rate is maintained constant when the difference between the maximum value and the minimum value of the exhaust flow rate within a predetermined reference time is less than a preset reference error. 9. The method of claim 8,
A step (S60) of judging whether the vehicle is forcibly regenerated when the vehicle is not traveling;
Wherein the DPF differential pressure sensor correction method comprises: 11. The method of claim 10,
(S70) if the corrected travel distance of the DPF differential pressure sensor (300) exceeds a predetermined second reference travel distance (B) when the vehicle is forcibly regenerated;
Wherein the DPF differential pressure sensor correction method comprises: 12. The method of claim 11,
(S50) when the corrected travel distance of the DPF differential pressure sensor (300) exceeds a predetermined second reference travel distance (B). delete delete

Images