METHOD OF EXPECTING N20 GENERATION ACCORDING TO OXIDATION OF NH3 IN SDPF

Abstract

A method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in an SDPF according to an exemplary embodiment of the present invention may include measuring an initial NH.sub.3 absorption amount in the SDPF, determining a first middle NH=3 absorption amount by subtracting an NH.sub.3 slip amount in the SDPF from the initial NH.sub.3 absorption amount in the SDPF, determining a second middle NH.sub.3 absorption amount by subtracting an NH.sub.3 amount oxidizing to NO.sub.x and N.sub.2 from the first middle NH.sub.3 absorption amount, determining N.sub.2O generation amount in the SDPF, and determining a final NH.sub.3 absorption amount in the SDPF by subtracting the N.sub.2O generation amount from the second middle NH.sub.3 absorption amount.

Claims

1. Method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in a selective catalytic reduction on diesel particulate filer (SDPF), comprising: measuring an initial NH.sub.3 absorption amount in the SDPF; determining a first middle NH.sub.3 absorption amount by subtracting an NH.sub.3 slip amount in the SDPF from the initial NH.sub.3 absorption amount in the SDPF; determining a second middle NH.sub.3 absorption amount by subtracting an NH.sub.3 amount oxidizing to NO.sub.x and N.sub.2 from the first middle NH.sub.3 absorption amount; determining an N.sub.2O generation amount in the SDPF; and determining a final NH.sub.3 absorption amount in the SDPF by subtracting the N.sub.2O generation amount from the second middle NH.sub.3 absorption amount.

2. The method of claim 1, wherein in determining the first middle NH.sub.3 absorption amount, the NH.sub.3 slip amount in the SDPF is a value determined by multiplying the initial NH.sub.3 absorption amount and an NH.sub.3 slip factor.

3. The method of claim 1, wherein in determining the second middle NH.sub.3 absorption amount, the NH.sub.3 amount oxidizing to NO.sub.x and N.sub.2 is a value determined by multiplying the first middle NH.sub.3 absorption amount and an oxidation factor oxidizing to NO.sub.x and N.sub.2.

4. The method of claim 1, wherein in determining the N.sub.2O generation amount in the SDPF, the N.sub.2O generation amount is a value determined by multiplying the second middle NH.sub.3 absorption amount and an N.sub.2O generation factor.

5. The method of claim 4, wherein the N.sub.2O generation factor is determined by considering a selective catalyst reduction (SCR) catalyst temperature, an NH.sub.3 absorption ratio in the SDPF, an exhaust gas flow amount, an NO density, and a degree of catalyst degradation.

6. The method of claim 5, wherein the SCR catalyst temperature is determined by measuring a exhaust gas temperature.

7. The method of claim 5, wherein an NO gas amount is determined by measuring an NO density.

8. The method of claim 5, wherein the degree of catalyst degradation is determined by a catalyst degradation map applying a catalyst degradation factor.

9. The method of claim 8, wherein the N.sub.2O generation factor is determined by: determining a first value by applying the SCR catalyst temperature and the NH.sub.3 absorption ratio in the SDPF to a first map; determining a second value by applying the exhaust gas flow amount and the NO density to a second map; determining a third value by applying the catalyst degradation factor to a third map; and multiplying the first value, the second value, and the third value together.

10. The method of claim 1, further including: determining an N.sub.2O slip amount by applying a transform constant using a map to the N.sub.2O generation amount; and determining an NH.sub.3 slip amount by subtracting the NO.sub.2 generation amount from the initial NH.sub.3 absorption amount in the SDPF.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a sequential chart illustrating a method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in an SDPF according to an exemplary embodiment of the present invention;

[0027] FIG. 2 is a sequential chart illustrating a method of determining N.sub.2O generation factor in the method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in an SDPF according to an exemplary embodiment of the present invention;

[0028] FIG. 3 is a flowchart illustrating a method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in an SDPF according to an exemplary embodiment of the present invention illustrated in FIG. 1;

[0029] FIG. 4 is a flowchart illustrating a method of determining N.sub.2O generation factor illustrated in FIG. 2; and

[0030] FIG. 5 is a graph showing a difference between final NH.sub.3 absorption amount in an SDPF according to a method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention and an actual measurement value.

[0031] It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

[0032] In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

[0033] Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(S) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

[0034] Furthermore, in exemplary embodiments, since like reference numerals designate like elements having the same configuration, a first exemplary embodiment is representatively described, and in other exemplary embodiments, only different configurations from the first exemplary embodiment will be described.

[0035] The drawings are schematic and are not illustrated in accordance with a scale. The relative sizes and ratios of the parts in the drawings are exaggerated or reduced for clarity and convenience, and the arbitrary sizes are only exemplary and are not limiting. The same structures, elements, or parts illustrated in no less than two drawings are denoted by the same reference numerals to represent similar characteristics. When a part is referred to as being on another portion, it can be directly on the other part or intervening parts may also be present.

[0036] Furthermore, the exemplary embodiments are not limited to a specific shape of an illustrated region, but, for example, include changes in shape in accordance with manufacturing.

[0037] Now, method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in an SDPF according to an exemplary embodiment of the present invention will be described with reference to FIG. 1 and FIG. 3.

[0038] FIG. 1 is a sequential chart illustrating a method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention, and FIG. 3 is a flowchart illustrating a method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention illustrated in FIG. 1.

[0039] Referring to FIG. 1 and FIG. 3, first, initial NH.sub.3 absorption amount (A, 100) in the SDPF is measured (S101).

[0040] As such, a first middle NH.sub.3 absorption amount (B, 200) is determined by subtracting the NH.sub.3 slip amount in the SDPF from the initial NH=3 absorption amount (A, 100) in the SDPF (S102). At the present time, the NH.sub.3 slip amount in the SDPF may be a value determined by multiplying the initial NH.sub.3 absorption amount (A, 100) and an NH.sub.3 slip factor.

[0041] As such, a second middle NH.sub.3 absorption amount (C, 300) is determined by subtracting the NH=3 amount oxidizing to NO.sub.x and N.sub.2 from the first middle NH.sub.3 absorption amount (B, 200) (S103). At the present time, the NH.sub.3 amount oxidizing to NO.sub.x and N.sub.2 may be a value determined by multiplying the first middle NH.sub.3 absorption amount (B, 200) and an oxidation factor oxidizing to NO.sub.x and N.sub.2.

[0042] As such, N.sub.2O generation amount in the SDPF is determined (S104), and a final NH.sub.3 absorption amount (final, 400) in the SDPF by subtracting the N.sub.2O generation amount from the second middle NH.sub.3 absorption amount (C, 300) (S105). At the present time, the N.sub.2O generation amount may be a value determined by multiplying the second middle NH=3 absorption amount (C, 300) and the N.sub.2O generation factor.

[0043] Meanwhile, method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention may further include determining N.sub.2O slip amount by applying a transform constant using a map to the N.sub.2O generation amount (S106), and determining NH.sub.3 slip amount by subtracting the NO.sub.2 generation amount from the initial NH.sub.3 absorption amount (A, 100) in the SDPF (S107).

[0044] For example, when the final NH.sub.3 absorption amount (final) is 100 mmol by applying method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention, the final NH.sub.3 absorption amount (final) may be 98 mmol when the method of expecting according to an exemplary embodiment of the present invention is not applied. The final NH.sub.3 absorption amount (final) which is 98 mmol becomes current absorption amount, and when NH.sub.3 amount absorbed in the SDPF when urea is injected is 2 mmol, the total absorption NH.sub.3 amount becomes 100 mmol. However, when the method of expecting according to an exemplary embodiment of the present invention is not applied, the total absorption NH.sub.3 amount becomes 102 mmol.

[0045] When the total absorption NH.sub.3 amount is 102 mmol, oxidation amount and N.sub.2O slip amount becomes more than when the total absorption NH.sub.3 amount is 100 mmol. The absorption amount accumulates, therefore the error value becomes larger.

[0046] FIG. 2 is a sequential chart illustrating a method of determining N.sub.2O generation factor in the method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention, and FIG. 4 is a flowchart illustrating a method of determining N.sub.2O generation factor illustrated in FIG. 2.

[0047] Referring to FIG. 2 and FIG. 4, in the step of determining N.sub.2O generation amount in the SDPF (S104), the N.sub.2O generation factor may be determined by considering SCR catalyst temperature, an NH.sub.3 absorption ratio in the SDPF, an exhaust gas flow amount, NO density, and a degree of catalyst degradation.

[0048] The SCR catalyst temperature may be determined by measuring the exhaust gas temperature, the NO gas amount may be determined by measuring NO density, and the degree of catalyst degradation may be determined by a catalyst degradation map applying a catalyst degradation factor.

[0049] Meanwhile, N.sub.2O generation factor may be determined by determining a first value by applying the SCR catalyst temperature and the NH.sub.3 absorption ratio in the SDPF to the first map 10 (S201), determining a second value by applying the exhaust gas flow amount and the NO density to a second map 20 (S202), determining a third value by applying the catalyst degradation factor to a third map 30 (S203), and multiplying the first value, the second value, and the third value together (S204). The first map 10 may be a map including numerical values predetermined by experiment of NH.sub.3 absorption in the SDPF with respect to a temperature of the SCR catalyst, the second map 20 may be a map including numerical values predetermined by experiment of NO density with respect to the exhaust gas flow amount, and the third map 30 may be a map including numerical values predetermined by experiment of the degree of catalyst degradation with respect to time.

[0050] FIG. 5 is a graph showing a difference between final NH.sub.3 absorption amount in the SDPF according to a method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention and an actual measurement value.

[0051] Referring to FIG. 5, in a transient driving mode, the final NH.sub.3 absorption amount in the SDPF increases as time passes.

[0052] A difference between the NH.sub.3 absorption amount (NH.sub.3 accumulation amount) when the method of expecting according to an exemplary embodiment of the present invention is not applied and an actual measurement value is greater than a difference between the NH.sub.3 absorption amount (NH.sub.3 accumulation amount) when applied and an actual measurement value.

[0053] By applying method of expecting N.sub.2O generation according to oxidation of NH.sub.3 in the SDPF according to an exemplary embodiment of the present invention, the error value between the NH.sub.3 absorption amount and the actual measurement value may be reduced.

[0054] Like the above, according to an exemplary embodiment of the present invention, modeling accuracy of the oxidation by-products may be improved.

[0055] Also, expectation of slip of NO.sub.x and NH.sub.3 at the rear end portion of the SDPF may be improved.

[0056] Also, through improvement of SDPF modeling accuracy, catalyst capacity may be decreased and manufacturing cost may be reduced.

[0057] For convenience in explanation and accurate definition in the appended claims, the terms upper, lower, up, down, upwards, downwards, internal, outer, inside, outside, inwardly, outwardly, internal, external, front, rear, back, forwards, and backwards are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

[0058] The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described to explain certain principles of the invention and their practical application, to enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.