KR101047608B1 - Apparatus for reducing exhaust gas of diesel vehicles and diagnostic methods thereof - Google Patents

Abstract

The present invention relates to an exhaust gas reduction device for a diesel vehicle and a failure diagnosis method thereof.

The present invention is a NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A high efficiency reducing agent conversion catalyst (DFC) disposed in front of the NOx purification catalyst and converting a reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity to supply the NOx purification catalyst; A reducing agent injection injector disposed in front of the high efficiency reducing agent conversion catalyst (DFC) to inject a reducing agent; And an oxygen sensor installed at the front end of the reducing agent injection injector and at the rear end of the NOx purification catalyst, at a front end and the rear end of the high efficiency reducing agent conversion catalyst (DFC), and at a front end and the rear end of the NOx purification catalyst. It is provided with a high-efficiency reducing agent conversion catalyst (DFC) and the catalyst diagnostic unit for diagnosing the failure of the NOx purification catalyst; provides an exhaust gas reduction device of a diesel vehicle comprising a.

According to the exhaust gas reducing device of the diesel vehicle of the present invention, since the supply of the reducing agent can be controlled by installing the secondary fuel injection injector for supplying the reducing agent, the reducing agent supply can be controlled according to the engine operating conditions, the catalyst conditions, etc. .

Emissions, Reduction, DFC

Description

Catalytic converter for exhaust gas of Diesel vehicle and Method for On Board Diagnosis

The present invention relates to an exhaust gas reduction device for a diesel vehicle and a failure diagnosis method thereof. More particularly, the present invention relates to an exhaust gas reduction device for a diesel vehicle and a failure diagnosis method thereof capable of diagnosing a failure of a catalyst and an injection injector in an exhaust gas reduction device for a diesel vehicle including a NOx purifying catalyst and a reducing agent injection injector.

In general, automobile exhaust gas refers to a gas produced by the combustion of a mixer in an engine and released into the atmosphere through an exhaust pipe, and the exhaust gas includes carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC). Contains a lot of harmful substances. Therefore, the diesel vehicle is equipped with an exhaust gas reduction device to reduce such harmful substances.

For this, a system that simultaneously reduces PM / NOx by using a diesel particulate filter (DPF) and LNT (Lean® NOx Trap) is called a NOx PM Reduction System (NPRS). It is used.

The particulate filter (DPF) collects particulate matter in the exhaust gas of a diesel engine using a trap and raises the particulate matter above the ignition temperature (about 650 degrees) at regular intervals to remove and regenerate the particulate matter. PM collection efficiency by DPF is known to be about 70% or more.

The NOx purifying catalyst is an exhaust gas purifying catalyst mainly purifying nitrogen oxides (NOx) in the exhaust gas. The NOx purifying catalyst occludes nitrogen oxides passing through the catalyst, and has an exhaust gas purifying function of reducing the nitrogen oxides stored into harmless nitrogen (N2) through the regeneration process. The NOx purification catalyst must be properly regenerated to maintain its performance and to continue its purification.

To this end, the NOx purification catalyst occludes NOx during the lean state operation of the theoretical air fuel ratio (λ)> 1, and changes the air-fuel ratio of the exhaust gas to the rich state of the theoretical fuel fuel ratio (λ) <1 through the engine control. It operates to desorb and reduce NOx stored in the NOx purification catalyst.

As such, in the related art, precise control is not performed according to a method of adjusting the air-fuel ratio of the engine to reduce NOx, that is, a control method based on lean / rich, and thus, there is a problem in that NOx reduction performance is reduced.

Accordingly, the present invention has been invented to solve such a problem, and provides an exhaust gas reduction device for a diesel vehicle that can efficiently reduce NOx because the NOx purification catalyst can be regenerated without controlling the engine air-fuel ratio. Its purpose is to.

In addition, the present invention can diagnose the failure of the catalyst and the reducing agent injection injector constituting the exhaust gas reducing device to inform the user and the exhaust gas reducing device of the diesel vehicle that can properly control the secondary injection by the reducing agent injection injector Its purpose is to provide a diagnostic method for faults.

The present invention is a NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A high efficiency reducing agent conversion catalyst (DFC) disposed in front of the NOx purification catalyst and converting a reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity to supply the NOx purification catalyst; A reducing agent injection injector disposed in front of the high efficiency reducing agent conversion catalyst (DFC) and an oxygen sensor installed at the front end of the reducing agent injection injector and the rear end of the NOx purification catalyst, and the high efficiency reducing agent conversion catalyst (DFC) A catalyst diagnostic unit for diagnosing the failure of the high efficiency reducing agent conversion catalyst (DFC) and the NOx purification catalyst having a temperature sensor installed at the front and rear ends and the front and rear ends of the NOx purification catalyst, respectively. Provide a gas reduction device.

The catalyst diagnosis unit diagnoses deterioration and failure of the catalysts by observing changes in oxygen concentration of the catalysts using the oxygen sensor and observing the exothermic reaction of the catalysts through the temperature sensor, and in case of failure, the catalyst injection injector It may be to stop the supply of reducing agent.

The catalyst diagnostic unit has a temperature difference between the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) smaller than a predetermined allowable value, the difference between the temperature difference between the front and rear ends of the NOx purification catalyst and the oxygen concentration is a predetermined amount or more, and the NOx purification rate is a certain amount. If smaller, a fault can be diagnosed.

The exhaust gas reducing apparatus of the diesel vehicle may further include a soot collecting filter (DPF) disposed at a rear end of the high efficiency reducing agent conversion catalyst (DFC) and a front end of the NOx purifying catalyst to collect and purify soot.

On the other hand, the present invention is a NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent diesel oxidation catalyst (DOC) disposed in front of the NOx purification catalyst; A soot collecting filter (DPF) disposed at a rear end of the diesel oxidation catalyst (DOC) to collect and purify soot; An oxygen sensor disposed at a front end of the diesel oxidation catalyst (DOC) and installed at a front end of the reducing agent injection injector and a front end of the reducing agent injection injector and a rear end of the NOx purification catalyst, and a front end of the diesel oxidation catalyst (DOC) And a catalytic diagnosis unit for diagnosing the failure of the diesel oxidation catalyst (DOC) and the NOx purification catalyst, including a temperature sensor installed at a rear end and a front end and a rear end of the NOx purification catalyst, respectively. do.

On the other hand, the present invention is a NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A reducing agent injection injector disposed in front of the NOx purification catalyst to inject a reducing agent; And an oxygen sensor installed at the front end of the reducing agent injection injector and the rear end of the NOx purification catalyst, and a temperature sensor installed at the front and rear ends of the NOx purification catalyst to diagnose deterioration and failure of the NOx purification catalyst. It provides a exhaust gas reducing device of a diesel vehicle comprising a diagnostic means for diagnosing the failure of the reducing agent injection injector.

In addition, NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A high efficiency reducing agent conversion catalyst (DFC) disposed in front of the NOx purification catalyst and converting a reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity to supply the NOx purification catalyst; And a reducing agent injection injector disposed at a front end of the high efficiency reducing agent conversion catalyst (DFC) to inject a reducing agent, wherein the exhaust gas reducing device of the diesel vehicle includes a front end of the reducing agent injection injector and a rear end of the NOx purification catalyst. Performance of the high efficiency reducing agent conversion catalyst (DFC) and the NOx purification catalyst using an oxygen sensor installed, and a temperature sensor installed at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) and the front and rear ends of the NOx purification catalyst, respectively. By observing the degradation, it provides a diagnostic method of the exhaust gas reduction device of the diesel vehicle for diagnosing the failure of the catalysts or the reducing agent injection injector.

In the failure diagnosis method of the catalysts or the reducing agent injection injector, the oxygen concentration of the catalysts is observed using the oxygen sensor, and the exothermic reaction of the catalysts is observed through the temperature sensor to detect the degradation and failure of the catalysts. A catalyst diagnosis step of diagnosing and a catalyst diagnosis step may include a failure determination step of determining a failure that the catalyst or the reducing agent injection injector is not opened.

The catalyst diagnosis step is to perform a failure determination step if the rate of change by the temperature difference by the temperature sensor located in the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) after the predetermined time has passed after the supply of the reducing agent is less than a certain amount Can be.

The catalyst diagnosis step may be performed when the rate of change by the temperature difference by the temperature sensor located in the front and rear of the NOx purifying catalyst is less than a predetermined amount after a predetermined time elapses after the supply of the reducing agent is completed.

In the catalyst diagnosis step, when the supply of the reducing agent is completed and a predetermined time has elapsed, the failure determination step may be performed when the difference in the amount of oxygen by the oxygen sensors located at the front and rear ends of the NOx purification catalyst is smaller than a second reference amount.

The failure determining step includes reducing agent injection injector failure when the difference in the rate of change of the high efficiency reducing agent conversion catalyst (DFC) and the NOx purification catalyst by the temperature difference at the front and rear ends, and the amount of oxygen at the front and rear ends of the NOx purification catalyst are smaller than a predetermined amount. It can be determined.

The failure determination step may include a change rate due to a temperature difference by a temperature sensor located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) less than a predetermined amount, and a change rate due to a temperature difference by a temperature sensor located at the front and rear ends of the NOx purification catalyst. And if the difference in the amount of oxygen by the oxygen sensor located in the front and rear end of the NOx purification catalyst is more than a certain amount, if the NOx purification rate is less than a certain amount it can be determined that the failure of the high efficiency reducing agent conversion catalyst (DFC).

The failure determination step may include a change rate due to a temperature difference by a temperature sensor positioned at a front end and a rear end of the high efficiency reducing agent conversion catalyst (DFC) at least a certain amount, and a change rate by a temperature difference caused by a temperature sensor located at a front end and a rear end of the NOx purification catalyst. If the amount is smaller than the predetermined amount, the difference in the amount of oxygen by the oxygen sensors located at the front and rear ends of the NOx purification catalyst is larger than the predetermined amount and the NOx purification rate is smaller than the predetermined amount, it may be determined that the NOx purification catalyst is broken.

If it is determined that the catalysts or the reducing agent injection injector is broken, it is preferable to notify the driver by turning on the failure information.

When it is determined that the reducing agent injection injector has failed, the fuel supply to the reducing agent injection injector may be stopped.

In the failure diagnosis method of the reducing agent injection injector, a catalyst diagnosis is performed by observing changes in oxygen concentration of the catalysts using the oxygen sensor and observing exothermic reactions of the catalysts through the temperature sensor. It may include a failure determination step of determining a failure that the reducing agent injection injector is not closed through the step and the catalyst diagnostic step.

In the catalyst diagnosis step, after the reducing agent is supplied, the purification of the NOx purifying catalyst is terminated and the operation of the reducing agent injection injector is stopped, the rate of change due to the temperature difference by the temperature sensor located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) If it is determined that the change is not reduced to the normal operating state and the heat generation changes continuously, the failure determination step may be performed.

In the catalyst diagnosis step, after the reductant is supplied to purify the NOx purification catalyst and the operation of the reducing agent injection injector is stopped, the change rate is determined by the temperature difference by the temperature difference between the front and rear ends of the NOx purification catalyst. When the change continuously occurs without returning to the normal operating state, the failure determination step may be performed.

The catalyst diagnosing step includes a supply of a reducing agent to terminate the purification of the NOx purifying catalyst and stopping the operation of the reducing agent injection injector, and when the difference in the amount of oxygen by the oxygen sensors located at the front and rear ends of the NOx purifying catalyst is maintained for a predetermined amount or more. The failure determination step may be performed.

The failure determination step includes a change rate due to a temperature difference by a temperature sensor located at the front and a rear end of the high efficiency reducing agent conversion catalyst (DFC) and a change rate due to a temperature difference by a temperature sensor located at the front and rear of the NOx purification catalyst. If it is large, it can be judged as a failure.

The failure determining step may include a rate of change by a temperature difference at a front end and a rear end of the high efficiency reducing agent conversion catalyst (DFC) being below a certain amount, and a temperature difference at a temperature end located at a front end and a rear end of the NOx purification catalyst. If the rate of change is greater than a certain amount, it can be judged as a failure.

The failure determining step includes a change rate due to a temperature difference by a temperature sensor located at the front and a rear end of the high efficiency reducing agent conversion catalyst (DFC) and a temperature change by a temperature difference at the front and rear ends of the NOx purification catalyst. When the difference in the amount of oxygen by the oxygen sensors located at the front and rear ends of the NOx purification catalyst is a predetermined amount or more, it may be determined as a failure.

If it is determined that the catalysts or the reducing agent injection injector is broken, it is preferable to notify the driver by lighting a failure alarm.

When it is determined that the reducing agent injection injector has failed, the fuel supply to the reducing agent injection injector may be stopped.

On the other hand, the present invention is a NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent diesel oxidation catalyst (DOC) disposed in front of the NOx purification catalyst; A soot collecting filter (DPF) disposed at a rear end of the diesel oxidation catalyst (DOC) to collect and purify soot; And a reducing agent injection injector disposed at a front end of the diesel oxidation catalyst (DOC) to inject a reducing agent, wherein the nitrogen oxide reduction device of the diesel vehicle includes a front end of the reducing agent injection injector and a rear end of the NOx purification catalyst. Diagnosis of the diesel oxidation catalyst (DOC) and NOx purification catalyst including an oxygen sensor installed, and a temperature sensor installed at the front and rear ends of the diesel oxidation catalyst (DOC) and the front and rear ends of the NOx purification catalyst, respectively. It provides a failure diagnosis method of the exhaust gas reducing device of a diesel vehicle characterized in that it further comprises a catalytic diagnostic unit.

In addition, the present invention is a NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent is disposed in front of the NOx purification catalyst to convert the reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity ability to supply to the NOx purification catalyst. High efficiency reducing agent conversion catalyst (DFC); And a reducing agent injection injector disposed at a front end of the high efficiency reducing agent conversion catalyst (DFC) to inject a reducing agent, wherein the exhaust gas reducing device of the diesel vehicle is installed at a front end of the reducing agent injection injector and a rear end of the NOx purification catalyst. Degradation performance of the high efficiency reducing agent conversion catalyst (DFC) and NOx purification catalyst, including an oxygen sensor, and a temperature sensor installed at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) and the front and rear ends of the NOx purification catalyst. Observe and provide a failure diagnosis method of the exhaust gas reducing device of the diesel vehicle for diagnosing the failure of the reducing agent injection injector.

According to the exhaust gas reducing device of the diesel vehicle of the present invention, since the supply of the reducing agent can be controlled by installing the secondary fuel injection injector for supplying the reducing agent, the reducing agent supply can be controlled according to the engine operating conditions, the catalyst conditions, etc. . Therefore, NOx can be efficiently reduced without performing separate engine air-fuel ratio control.

In addition, according to the failure diagnosis method of the exhaust gas reducing device of the present invention, it is possible to diagnose the failure of the catalyst and the reducing agent injection injector constituting the exhaust gas reducing device and notify the user, and to control the secondary injection by the reducing agent injection injector appropriately. can do.

The present invention is a NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent is disposed in front of the NOx purification catalyst to convert the reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity ability to supply to the NOx purification catalyst Conversion catalyst (DFC); And a reducing agent injection injector disposed at a front end of the high efficiency reducing agent conversion catalyst (DFC) to inject a reducing agent.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a schematic configuration diagram according to a first embodiment of an exhaust gas reducing device of a diesel vehicle of the present invention.

As shown in FIG. 1, the exhaust gas reducing device of the present embodiment is mounted on an exhaust pipe connected to the rear end of the engine 10 and sequentially purifies a high efficiency reducing agent conversion catalyst (DFC, 20), a particulate filter (DPF, 30), and NOx purification. It has a structure in which the catalyst 40 is arrange | positioned.

The NOx purification catalyst 40 reduces nitrogen oxides (NOx) in the exhaust gas by using at least one or more reducing agents among reducing agents such as HC (Hydrocarbon), CO, and H ₂ .

The particulate filter (DPF) 30 is disposed at the rear end of the high efficiency reducing agent conversion catalyst (DFC) 20 and the front end of the NOx purification catalyst 40 to collect and purify CO, THC, and PM in the exhaust gas.

The high efficiency reducing agent conversion catalyst (DFC) 20 is disposed in front of the NOx purification catalyst 40 to convert the reducing agent supplied to the NOx purification catalyst 40 into a plurality of reducing agents having high nitrogen oxide reduction reactivity, thereby purifying the NOx. It serves to supply the catalyst (40). Here, the front end of the high efficiency reducing agent conversion catalyst (DFC, 20) is equipped with a reducing agent injection injector 50 for injecting a reducing agent.

Accordingly, the high efficiency reducing agent conversion catalyst (DFC) 20 contains oxygen having high reactivity by increasing the effective reaction surface area by making the fuel injected by the reducing agent injection injector 50, that is, a plurality of HCs having high efficiency, increased. Will produce HC, CO and H2.

Due to the exothermic reaction generated during the fuel decomposition process, the rear end temperature of the high efficiency reducing agent conversion catalyst (DFC) 20 is increased to improve the NOx purification efficiency.

On the other hand, the exhaust gas reducing device of the diesel vehicle of the present embodiment is the oxygen sensor (1, 2) installed in the front end of the reducing agent injection injector 50 and the rear end of the NOx purification catalyst 40, and the high efficiency reducing agent conversion catalyst The high efficiency reducing agent conversion catalyst (DFC, 20), including temperature sensors (T4, T5, T6, and T7) installed at the front and rear ends of the (DFC, 20) and the front and rear ends of the NOx purification catalyst (40), respectively. It further comprises a catalyst diagnostic unit for diagnosing the failure of the NOx purifying catalyst 40.

The catalyst diagnosis unit observes oxygen concentration changes of the catalysts 20 and 40 using the oxygen sensors 1 and 2, and the catalysts 20 through the temperature sensors T4, T5, T6, and T7. , 40 to diagnose the deterioration and failure of the catalysts (20, 40), and to stop the fuel supply of the reducing agent injection injector 50 in the event of a failure.

Hereinafter, a failure diagnosis method of the exhaust gas reducing device of the present embodiment will be described.

2 is a flowchart illustrating a failure diagnosis method of the exhaust gas reducing apparatus of FIG. 1, and FIG. 3 is a flowchart embodying the method of FIG. 2.

As illustrated in FIG. 2, the method for diagnosing a failure of the exhaust gas reducing device of the present embodiment includes a secondary injection end step (S110) in which secondary injection injected by the reducing agent injection injector 50 is ended, and injection of the reducing agent is terminated. After the catalyst diagnosis step (S120) for diagnosing deterioration and performance of the NOx purification catalyst 40 and the high efficiency reducing agent conversion catalyst (DFC, 20), and the catalyst and reducing agent injection injector (50) as a diagnostic result of the catalyst diagnosis step (S120) ) May be divided into a failure determination step (S130) of determining a failure, a step (S140) of lighting failure information when determined to be a failure, and a step (S150) of stopping supply of secondary injection fuel.

More specifically, as illustrated in FIG. 3, the NOx purification catalyst 40 and the particulate filter of the exhaust gas reducing device of the present invention in the normal driving state as shown in FIG. 3 are NOx regeneration, DPF regeneration, and desulfurization regeneration. Etc., the playback process (S5) is started.

At this time, when the secondary injection is terminated by the reducing agent injection injector 50 (S110), the catalyst diagnosis step (S120) of diagnosing the failure of the catalyst is performed.

The catalyst diagnosis step (S120) is to observe the oxygen concentration change of the catalysts (20, 40) using the oxygen sensor (1, 2), and through the temperature sensors (T4, T5, T6, T7) By observing the exothermic reaction of the catalysts 20, 40, the degradation and failure of the catalysts are diagnosed.

That is, the catalyst diagnosis step (S120) is the rate of change by the temperature difference by the temperature sensor (T4, T5) located in the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC, 20) after a predetermined time after the supply of the reducing agent is completed (T_DFC_diff) and the rate of change (T_NOx purification catalyst_diff) due to the temperature difference by temperature sensors (T6, T7) located at the front and rear ends of the NOx purification catalyst 40 after a predetermined time has passed since the supply of the reducing agent is started. In addition, the rate of change of the amount of oxygen (O2_diff) by the oxygen sensors 1 and 2 positioned at the front and rear ends of the NOx purification catalyst 40 is determined (S121).

Here, it is determined by the change rate (T_DFC_diff) by the temperature difference by the temperature sensors (T4, T5) located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC, 20) (S122) Subsequently, it is determined whether the rate of change (T_NOx purification catalyst _diff) due to the temperature difference by the temperature sensors T6 and T7 located at the front and rear ends of the NOx purification catalyst 40 is greater than or equal to a predetermined size β (S123). And satisfies all conditions by determining whether the rate of change (O2_diff) of the amount of oxygen by the oxygen sensors 1 and 2 positioned at the front and rear ends of the NOx purification catalyst 40 exceeds the first reference amount (S124). Proceed to normal operation.

However, if it is smaller than a predetermined amount (<α) by determining the change rate (T_DFC_diff) due to the temperature difference by the temperature sensors T4 and T5 located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) 20 (<α), the NOx The rate of change (T_NOx purification catalyst_diff) due to the temperature difference by the temperature sensors T6 and T7 located at the front and rear ends of the purification catalyst 40 is determined (S131).

Here, the rate of change (T_NOx purification catalyst _diff) due to the temperature difference by the temperature sensors T6 and T7 located at the front and rear ends of the NOx purification catalyst 40 is determined (S131) and is less than a predetermined amount (<β). Determining the change rate (O2_diff) of the oxygen amount by the oxygen sensor (1, 2) located in the front and rear of the purification catalyst 40 (S134), if less than the second reference amount (0.5) generates an injector failure code (S140) After turning on the MIL (S141), the secondary injection fuel line is cut off (S150).

That is, the failure determination step (S130) is a change rate (S122, S131) due to the temperature difference in the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC, 20) and the NOx purification catalyst 40 is smaller than a predetermined amount, NOx purification catalyst When the difference in the amount of oxygen at the front end and the rear end of 40 is smaller than the second reference amount 0.5 (S134), it can be determined as a failure.

In addition, it is determined by the rate of change by the temperature difference by the temperature sensors (T6, T7) located at the front and rear ends of the NOx purification catalyst 40 (S123, S131) is less than a predetermined amount (<β), the NOx purification catalyst 40 If the difference in the amount of oxygen by the oxygen sensors (1, 2) located at the front and rear ends of) does not exceed the first reference amount (1) (S132), it is smaller than the second reference amount (0.5) compared to the second reference amount (0.5). It can be determined that the failure (S134).

Here, if the difference in the amount of oxygen by the oxygen sensors 1 and 2 located at the front and rear ends of the NOx purification catalyst 40 exceeds the first reference amount 1 (S132), is the NOx purification rate smaller than a specific ratio (x)? It is determined whether or not (S133).

At this time, if the NOx purification rate is less than the specific ratio (x), the MIL is turned on (S142, ②) and the secondary injection fuel line is shut off (S150). During the injection, the secondary injection pattern is corrected (S160) to restore the lowered NOx purification rate.

Of course, the failure determination step (S130) is the rate of change by the temperature difference by the temperature sensor (T4, T5) located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC, 20) is less than a predetermined amount, the NOx purification catalyst ( The difference in the rate of change by the temperature difference by the temperature sensors T6 and T7 located at the front and rear ends of 40) and the amount of oxygen by the oxygen sensors 1 and 2 located at the front and rear ends of the NOx purifying catalyst 40 are both above a certain amount. If the NOx purification rate is less than a certain amount, it can be determined as a failure (S142, ①) of the high efficiency reducing agent conversion catalyst (DFC, 20).

Wherein the failure determination step (S130) is a change rate by the temperature difference by the temperature sensor (T4, T5) located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC, 20) is more than one quantitative, the NOx purifying catalyst (40) The rate of change due to the temperature difference by the temperature sensors T6 and T7 located at the front and the rear ends of the step) is smaller than a predetermined amount, and the difference in the amount of oxygen by the oxygen sensors 1 and 2 located at the front and rear ends of the NOx purification catalyst 40 is reduced. If it is larger than the predetermined amount and the NOx purification rate is smaller than the predetermined amount, it may be determined as a failure (S142, ②) of the NOx purification catalyst 40.

Thus, when it is determined that the catalysts (high efficiency reducing agent conversion catalyst (DFC, 20), NOx purifying catalyst 40) or the reducing agent injection injector 50 is broken, a failure alarm (for example, MIL) is turned on (S141, S142) to inform the driver. Subsequently, the fuel supply to the reducing agent injection injector 50 is stopped, that is, the secondary injection fuel line is blocked (S150).

FIG. 4 is a flowchart of another embodiment embodying the method of FIG. 2 to the failure diagnosis method of the exhaust gas reducing device of FIG. 1.

As shown in FIG. 4, the catalyst diagnosing step (S120) is performed after the refining agent is supplied to purify the NOx purifying catalyst 40 and the operation of the reducing agent injection injector 50 is completed and a predetermined time elapses. Judging by the rate of change by the temperature difference by the temperature sensors (T4, T5) located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC, 20), if the change is not reduced to the normal operation state and the calorific value changes continuously (S122 ') A failure determination step (S130) of determining a failure of the closing of the reducing agent injection injector may be performed.

After the reducing agent is supplied to purify the NOx purification catalyst 40 and the operation of the reducing agent injection injector 50 is completed and a predetermined time elapses, a temperature sensor located at the front and rear ends of the NOx purification catalyst 40. Judging by the rate of change due to the temperature difference according to (T6, T7), when the change does not return to the normal operating state and when the change occurs continuously (S123 ', S131'), the failure judgment that determines the failure of closing the reducing agent injection injector Step S130 may be performed.

In addition, after the reducing agent is supplied to purify the NOx purification catalyst 40 and the operation of the reducing agent injection injector 50 is completed and a predetermined time elapses, the oxygen sensor located at the front and rear ends of the NOx purification catalyst 40. When the difference in the amount of oxygen by (1, 2) is maintained for more than a predetermined amount (S124 ') it may be performed a failure determination step (S130) for determining the non-closed failure of the reducing agent injection injector.

And if it is determined that the reducing agent injection injector 50 is a failure (S140 ') to inform the driver by lighting the failure information (S141), if the reducing agent injection injector 50 is determined to be a failure to the reducing agent injection injector 50 The fuel supply may be stopped (S150).

5 is a schematic configuration diagram according to a second embodiment of the exhaust gas reducing device of the diesel vehicle of the present invention.

On the other hand, according to another embodiment of the present invention, the exhaust gas reducing device of a diesel vehicle is connected to the tail exhaust pipe side connected to the engine 10 is NOx purification catalyst 40 for reducing nitrogen oxides (NOx) using a reducing agent, A diesel oxidation catalyst (DOC) is disposed at the rear end of the exhaust pipe adjacent to the engine 10 and in front of the NOx purification catalyst 40, and a smoke collection filter for collecting and purifying soot at the rear end of the diesel oxidation catalyst (DOC). DPF) is disposed, and a reducing agent injection injector 50 for injecting a reducing agent may be disposed at the front end of the diesel oxidation catalyst (DOC).

The nitrogen oxide reduction device of the diesel vehicle is the oxygen sensor (1, 2) of the front end of the reducing agent injection injector 50 and the rear end of the NOx purification catalyst 40 and the diesel oxidation catalyst (DOC) of Including the front and rear stage and the temperature sensor (T4, T5, T6, T7) installed at the front and rear ends of the NOx purification catalyst 40, the failure of the diesel oxidation catalyst (DOC) and NOx purification catalyst 40 The diagnosis may further include a catalytic diagnosis unit.

The exhaust gas reducing device of the diesel vehicle according to the second embodiment of the present invention also has the same failure diagnosis method as the first embodiment described above, and the high efficiency reducing agent conversion catalyst (DFC) 20 shown in FIGS. If it is understood that the diesel oxidation catalyst (DOC) is replaced in place it will be understood that the diagnostic method of the present embodiment.

6 is a schematic configuration diagram according to a third embodiment of the exhaust gas reducing device of a diesel vehicle of the present invention.

On the other hand, according to another embodiment of the present invention, the exhaust gas reducing device of a diesel vehicle is connected to the tail exhaust pipe side connected to the engine 10 is NOx purification catalyst 40 for reducing nitrogen oxides (NOx) using a reducing agent, In the exhaust pipe of the rear end of the engine 10 and the front end of the NOx purification catalyst 40, a reducing agent injection injector 50 for injecting a reducing agent is installed.

In addition, oxygen sensors 1 and 2 installed at the front end of the reducing agent injection injector 50 and the rear end of the NOx purification catalyst 40, respectively, and the temperature sensors installed at the front end and the rear end of the NOx purification catalyst 40, respectively. It includes (T6, T7) to diagnose the failure of the reducing agent injection injector 50, including a catalyst diagnostic unit for diagnosing the degradation and failure of the NOx purification catalyst 40.

In the present embodiment, the temperature sensor T6 and T7 and the oxygen sensors 1 and 2 may be used to diagnose deterioration and failure of the NOx purification catalyst 40 using the same methods as described above. do.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a schematic configuration diagram according to a first embodiment of an exhaust gas reducing device of a diesel vehicle of the present invention.

2 is a flowchart illustrating a failure diagnosis method of the exhaust gas reducing device of FIG. 1.

FIG. 3 is a flowchart of one embodiment embodying the method of FIG. 2. FIG.

4 is another flow diagram embodying the method of FIG.

Figure 5 is a schematic configuration diagram according to a second embodiment of the exhaust gas reducing device of a diesel vehicle of the present invention.

Figure 6 is a schematic configuration diagram according to a third embodiment of the exhaust gas reducing device of a diesel vehicle of the present invention.

<Description of reference numerals for main parts of the drawings>

1, 2: oxygen sensor 10: engine

20: high efficiency reducing agent conversion catalyst (DFC) 25: diesel oxidation catalyst (DOC)

30: soot filtration device (DPF) 40: NOx purification catalyst

50: reducing agent injection injector T4, T5, T6, T7: temperature sensor

Claims (27)

NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A high efficiency reducing agent conversion catalyst (DFC) disposed in front of the NOx purification catalyst and converting a reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity to supply the NOx purification catalyst; A reducing agent injection injector disposed in front of the high efficiency reducing agent conversion catalyst (DFC) to inject a reducing agent; And An oxygen sensor provided at the front end of the reducing agent injection injector and the rear end of the NOx purification catalyst, and at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) and at the front and rear ends of the NOx purification catalyst. And a catalyst diagnosis unit for diagnosing the failure of the high efficiency reducing agent conversion catalyst (DFC) and the NOx purifying catalyst. The method of claim 1, The catalyst diagnostic unit Observe the oxygen concentration change of the catalysts using the oxygen sensor, diagnose the deterioration and failure of the catalysts by observing the exothermic reaction of the catalysts through the temperature sensor, and stop supplying the reducing agent to the reducing agent injection injector in case of failure. An exhaust gas reduction device for a diesel vehicle, characterized by the above-mentioned. The method of claim 2, The catalyst diagnostic unit When the temperature difference between the front end and the rear end of the high efficiency reducing agent conversion catalyst (DFC) is smaller than a predetermined allowable value, the temperature difference between the front end and the rear end of the NOx purification catalyst and the oxygen concentration difference is more than a certain amount, and the NOx purification rate is smaller than a certain amount, An exhaust gas reduction device for a diesel vehicle, characterized by a diagnosis as a failure. The method according to any one of claims 1 to 3, The exhaust gas reducing device of the diesel vehicle, And a particulate filter (DPF) disposed at a rear end of the high efficiency reducing agent conversion catalyst (DFC) and at a front end of the NOx purification catalyst to collect and purify the soot. NOx purification catalyst to reduce nitrogen oxide (NOx) by using reducing agent A diesel oxidation catalyst (DOC) disposed in front of the NOx purification catalyst; A soot collecting filter (DPF) disposed at a rear end of the diesel oxidation catalyst (DOC) to collect and purify soot; A reducing agent injection injector disposed at a front end of the diesel oxidation catalyst (DOC) to inject a reducing agent; And An oxygen sensor installed at the front end of the reducing agent injection injector and the rear end of the NOx purification catalyst, and a temperature sensor installed at the front and rear ends of the diesel oxidation catalyst (DOC) and at the front and rear ends of the NOx purification catalyst, respectively. And a catalytic diagnosis unit for diagnosing the failure of the diesel oxidation catalyst (DOC) and the NOx purification catalyst. NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A reducing agent injection injector disposed in front of the NOx purification catalyst to inject a reducing agent; And A catalyst for diagnosing deterioration and failure of the NOx purification catalyst having an oxygen sensor installed at the front end of the reducing agent injection injector and the rear end of the NOx purification catalyst, and a temperature sensor installed at the front and rear ends of the NOx purification catalyst, respectively. Diagnosis unit; exhaust gas reducing device of the diesel vehicle, characterized in that for diagnosing the failure of the reducing agent injection injector. NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A high efficiency reducing agent conversion catalyst (DFC) disposed in front of the NOx purification catalyst and converting a reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity to supply the NOx purification catalyst; And a reducing agent injection injector disposed at a front end of the high efficiency reducing agent conversion catalyst (DFC) to inject a reducing agent. Oxygen sensors are provided at the front end of the reducing agent injection injector and the rear end of the NOx purification catalyst, and at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) and at the front and rear ends of the NOx purification catalyst, respectively. And diagnosing the failure of the catalysts or the reducing agent injection injector by observing deterioration of the high efficiency reducing agent conversion catalyst (DFC) and the NOx purification catalyst. The method of claim 7, wherein The failure diagnosis method of the catalysts or the reducing agent injection injector, A catalyst diagnosis step of diagnosing deterioration and failure of the catalysts by observing a change in oxygen concentration of the catalysts using the oxygen sensor and observing an exothermic reaction of the catalysts through the temperature sensor; And And a failure determination step of determining a failure of the catalysts or a failure in which the reducing agent injection injector is not opened through the catalyst diagnosis step. The method of claim 8, The catalyst diagnosis step After the supply of the reducing agent is completed and a predetermined time has elapsed, if the rate of change by the temperature difference by the temperature sensor located in the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) is less than a predetermined amount, characterized in that for performing a failure determination step Method for diagnosing faults in a vehicle's exhaust gas reducing device. 10. The method of claim 9, The catalyst diagnosis step After the supply of the reducing agent is completed and a predetermined time elapses, if the rate of change by the temperature difference by the temperature sensor located at the front and rear ends of the NOx purification catalyst is less than a certain amount, exhausting the diesel vehicle, characterized in that the failure determination step is performed. Method of diagnosing failure of the gas abatement device. The method of claim 10, The catalyst diagnosis step After the supply of the reducing agent is completed and a predetermined time has elapsed when the difference in the amount of oxygen by the oxygen sensor located in the front and rear ends of the NOx purification catalyst is less than the second reference amount is the exhaust of the diesel vehicle, characterized in that for performing Method of diagnosing failure of the gas abatement device. The method of claim 11, The failure determination step When the difference between the change rate of the high efficiency reducing agent conversion catalyst (DFC) and the NOx purification catalyst by the temperature difference in the front and rear stage, the oxygen amount in the front and rear stage of the NOx purification catalyst is less than a certain amount, it is determined that the reducing agent injection injector failure Failure diagnosis method of the exhaust gas reducing device of a diesel vehicle. The method of claim 11, The failure determination step The rate of change by the temperature difference by the temperature sensor located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) is less than a predetermined amount, and the rate of change by the temperature difference by the temperature sensor located at the front and rear ends of the NOx purification catalyst and the NOx purification catalyst When the difference in the amount of oxygen by the oxygen sensor located at the front and rear of the gas is greater than or equal to a certain amount, and the NOx purification rate is less than the predetermined amount, it is determined that the high efficiency reducing agent conversion catalyst (DFC) is malfunctioning. How to diagnose faults. The method of claim 10, The failure determination step The rate of change by the temperature difference by the temperature sensor located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) is more than a certain amount, the rate of change by the temperature difference by the temperature sensor located at the front and rear of the NOx purification catalyst is less than a certain amount, If the difference in the amount of oxygen by the oxygen sensor located in the front and rear of the NOx purification catalyst is greater than a certain amount and the NOx purification rate is less than a certain amount, it is determined that the failure of the NOx purification catalyst of the diesel vehicle, characterized in that the failure of the exhaust gas reducing device of the diesel vehicle Way. The method according to any one of claims 12 to 14, If it is determined that the catalysts or the reducing agent injection injector is a failure, a failure diagnosis method of the exhaust gas reduction device of a diesel vehicle, characterized in that to inform the driver by lighting the failure information. The method of claim 15, When the reducing agent injection injector is determined to be a failure, the supply of fuel to the reducing agent injection injector characterized in that the failure diagnosis method of the exhaust gas reducing device of the diesel vehicle. The method of claim 7, wherein The failure diagnosis method of the reducing agent injection injector, A catalyst diagnosis step of diagnosing deterioration and failure of the catalysts by observing a change in oxygen concentration of the catalysts using the oxygen sensor and observing an exothermic reaction of the catalysts through the temperature sensor; And And a failure determination step of determining a failure that the reducing agent injection injector is not closed through the catalyst diagnosis step. The method of claim 17, The catalyst diagnosis step After the supply of a reducing agent terminates the purification of the NOx purifying catalyst and stops the operation of the reducing agent injection injector, the change is judged by the change rate due to the temperature difference by the temperature sensor located at the front and rear of the high efficiency reducing agent conversion catalyst (DFC). The failure diagnosis method of the exhaust gas reduction device of a diesel vehicle, characterized in that for performing a failure determination step if the heat generation changes continuously without reducing to the normal operating state. The method of claim 17, The catalyst diagnosis step After the reducing agent is supplied and the purification of the NOx purification catalyst is finished and the operation of the reducing agent injection injector is stopped, the change is determined to be in the normal operation state by judging the rate of change by the temperature difference by the temperature sensor located at the front and the rear of the NOx purification catalyst. The failure diagnosis method of the exhaust gas reduction device of a diesel vehicle, characterized in that for performing a failure determination step when the change occurs continuously without reduction. The method of claim 17, The catalyst diagnosis step Determination step of the failure when the difference in the amount of oxygen by the oxygen sensor located in the front and rear ends of the NOx purification catalyst after the purification of the NOx purification catalyst is terminated and the operation of the reducing agent injection injector is stopped after supplying a reducing agent Failure diagnosis method of the exhaust gas reducing device of a diesel vehicle to perform the. The method according to any one of claims 18 to 20, The failure determination step If the rate of change by the temperature difference at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) and the rate of change by the temperature difference at the front and rear ends of the NOx purification catalyst are both greater than a predetermined amount, a failure is determined. A method for diagnosing a failure of an exhaust gas reducing device of a diesel vehicle. The method according to any one of claims 18 to 20, The failure determination step If the rate of change by the temperature difference at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) is below a certain amount, and the rate of change by the temperature difference at the front and rear ends of the NOx purification catalyst is greater than a certain amount, the fault occurs. The failure diagnosis method of the exhaust gas reduction device of a diesel vehicle, characterized in that judged. The method according to any one of claims 18 to 20, The failure determination step The rate of change by the temperature difference by the temperature sensors located at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC) and the rate of change by the temperature difference by the temperature sensors located at the front and rear ends of the NOx purification catalyst are both below a certain amount, and the NOx purification If the difference in the amount of oxygen by the oxygen sensor located in the front and rear of the catalyst is a certain amount or more, the failure diagnosis method of the exhaust gas reducing device of the diesel vehicle characterized in that it is determined to be a failure. The method according to any one of claims 18 to 20, When the catalysts or the reducing agent injection injector is determined to be a failure, the failure warning method of the exhaust gas reduction device of the diesel vehicle, characterized in that to inform the driver by turning on a failure alarm. The method of claim 24, When the reducing agent injection injector is determined to be a failure, the supply of fuel to the reducing agent injection injector characterized in that the failure diagnosis method of the exhaust gas reducing device of the diesel vehicle. NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent Diesel oxidation catalyst (DOC) disposed in front of the NOx purification catalyst; A soot collecting filter (DPF) disposed at a rear end of the diesel oxidation catalyst (DOC) to collect and purify soot; And a reducing agent injection injector disposed at a front end of the diesel oxidation catalyst (DOC) to inject a reducing agent. An apparatus for reducing nitrogen oxides in the diesel vehicle includes an oxygen sensor installed at a front end of the reducing agent injection injector and a rear end of the NOx purification catalyst, a front end and a rear end of the diesel oxidation catalyst (DOC), and a front end of the NOx purification catalyst and And a catalyst diagnosis unit for diagnosing the failure of the diesel oxidation catalyst (DOC) and the NOx purifying catalyst by using a temperature sensor respectively installed at a rear end thereof. NOx purification catalyst for reducing nitrogen oxides (NOx) using a reducing agent; A high efficiency reducing agent conversion catalyst (DFC) disposed in front of the NOx purification catalyst and converting a reducing agent into a plurality of reducing agents having high nitrogen oxide reduction reactivity to supply the NOx purification catalyst; And a reducing agent injection injector disposed at a front end of the high efficiency reducing agent conversion catalyst (DFC) to inject a reducing agent. Oxygen sensors are provided at the front end of the reducing agent injection injector and the rear end of the NOx purification catalyst, and at the front and rear ends of the high efficiency reducing agent conversion catalyst (DFC), and at the front and rear ends of the NOx purification catalyst, respectively. To observe the deterioration of the high efficiency reducing agent conversion catalyst (DFC) and the NOx purifying catalyst to diagnose a failure of the reducing agent injection injector.

Images