KR20220097082A - Method and System of Diagnosing Leakage in Urea Pump Line Included in Exhaust Gas After Treatment Device for Diesel Engine - Google Patents

Abstract

Disclosed are a method and a system for diagnosing leakage in a urea pump line included in an exhaust gas after treatment apparatus for a diesel engine. According to one embodiment of the present invention, the system for diagnosing leakage in the urea pump line included in the exhaust gas after treatment apparatus for the diesel engine comprises: an after treatment unit configured to reduce the concentration of nitrogen oxides (NO_x) in exhaust gas generated from the engine by using urea; a first concentration sensor measuring the concentration of NO_x in the exhaust gas before passing through the after treatment unit; a second concentration sensor measuring the concentration of NO_x in the exhaust gas after passing through the after treatment unit; a urea tank storing urea water solution; a urea pump configured to take out and pressurize the urea water solution in the urea tank and having a pressure sensor measuring the pressure of the pressurized urea water solution; a dosing module configured to spray the pressurized urea water solution to the after treatment unit; a pump line configured to transfer the urea water solution pressurized by the urea pump to the dosing module; and a leakage determining unit configured to determine the presence or absence of leakage from the pump line based on the difference in the concentration value between the first concentration sensor and the second concentration sensor and the presence or absence of an increase in the pressure value measured by the pressure sensor. Accordingly, the presence or absence of leakage in the urea pump line can be diagnosed even without mounting an additional sensor.

Description

Method and System of Diagnosing Leakage in Urea Pump Line Included in Exhaust Gas After Treatment Device for Diesel Engine

The present disclosure relates to a method and system for diagnosing a leak in a urea pump line provided in an exhaust gas aftertreatment device for a diesel engine.

The content described in this section merely provides background information for the present disclosure and does not constitute the prior art.

As interest in air environment improvement has recently increased, internal combustion engines using fossil fuels have been pointed out as the main cause of environmental pollution. For this reason, exhaust gas regulations of internal combustion engines have been strengthened, and various exhaust gas reduction technologies are being developed to satisfy the strengthened regulations.

The proportion of exhaust gas generation from internal combustion engines is generally concentrated in transportation means, and exhaust gases from on-road vehicles as well as non-road vehicles are increasing. Non-road vehicles include, for example, construction machinery, agricultural machinery, locomotives, and the like, and since these vehicles mainly use a diesel engine, a lot of nitrogen oxides (NOx) that cause air pollution are emitted due to the characteristics of the engine.

The emission of nitrogen oxides (NOx) is greatly affected by the combustion temperature and fuel injection conditions. An exhaust gas aftertreatment device such as SCR (Selective Catalyst Reduction) is provided. Among them, SCR injects a reducing agent such as ammonia (NH3) in the flow direction of the exhaust gas to induce a catalytic reaction between nitrogen oxide (NOx) and ammonia (NH3) in the exhaust gas, and finally nitrogen gas (N2) ) and water (H20) are configured to be discharged to the atmosphere.

On the other hand, ammonia injection in the SCR is made in such a way that ammonia stored in a tank is injected at a high pressure from an injector toward the exhaust gas through a pump. Therefore, when a failure occurs in the line through which ammonia is injected, it should be possible to diagnose it. In particular, when a leak occurs in a pump line through which ammonia flows at a high pressure, ammonia cannot be injected at a high pressure, so a method for determining this is required.

Accordingly, the present disclosure is intended to solve these problems, and a main object of the present disclosure is to provide a method and a system capable of diagnosing whether a leak occurs in a pump line without mounting a separate sensor on the pump line.

According to an embodiment of the present disclosure for achieving this object, an after treatment unit configured to reduce nitrogen oxide (NOx) concentration of exhaust gas generated from an engine by using urea (urea) ; a first concentration sensor for measuring the nitrogen oxide concentration of the exhaust gas before passing through the post-processing unit; a second concentration sensor for measuring the nitrogen oxide concentration of the exhaust gas that has passed through the post-processing unit; a urea tank in which an aqueous urea solution is stored; a urea pump configured to withdraw and pressurize the urea aqueous solution in the urea tank, and have a pressure sensor for measuring the pressure of the pressurized urea aqueous solution; a dosing module configured to spray the pressurized urea aqueous solution into the post-processing unit; a pump line configured to deliver the urea aqueous solution pressurized by the urea pump to the dosing module; and a leak determination unit configured to determine whether leakage of the pump line has occurred based on the difference between the concentration values measured by the first concentration sensor and the second concentration sensor and whether the pressure value measured by the pressure sensor increases. It provides a leak diagnosis system comprising a determining unit).

In addition, there is provided a method for diagnosing a leak by a leak determination unit of an exhaust gas post-processing device, the method comprising: receiving a nitrogen oxide concentration value of exhaust gas generated from an engine from a first concentration sensor; When the urea pump draws out and pressurizes the urea aqueous solution stored in the urea tank, and the urea aqueous solution is delivered to the dosing module using a pump line, the pressure value of the pressurized urea aqueous solution is received from the pressure sensor included in the urea pump process; receiving a nitrogen oxide concentration value of the exhaust gas that has passed through the post-processing unit configured to reduce the nitrogen oxide concentration of the exhaust gas from a second concentration sensor; determining whether a difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value; If the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value, determining whether the pressure value of the aqueous urea solution received from the pressure sensor increases; And when the pressure value of the aqueous urea solution received from the pressure sensor does not increase, it provides a leak diagnosis method comprising the step of determining that a leak has occurred in the pump line.

As described above, according to the present embodiment, there is an effect of diagnosing whether a leak occurs in the pump line without installing a separate sensor on the pump line.

1 is a view showing a leak diagnosis system according to an embodiment of the present disclosure.
2 is a flowchart illustrating a leak diagnosis method according to an embodiment of the present disclosure.

Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary drawings. In adding reference numerals to components in each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present disclosure, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present disclosure, the detailed description thereof will be omitted.

In describing the components of the embodiment according to the present disclosure, reference numerals such as first, second, i), ii), a), b) may be used. These signs are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the signs. In the specification, when a part 'includes' or 'includes' a certain element, it means that other elements may be further included, rather than excluding other elements, unless explicitly stated otherwise. .

1 is a view showing a leak diagnosis system according to an embodiment of the present disclosure.

Referring to FIG. 1 , the leak diagnosis system includes an engine 100, an after treatment unit 120, a first concentration sensor 115, and a second concentration sensor 135. , urea tank (140), urea pump (urea pump, 150), dosing module (170), pump line (pump line, 160) and all of the leak determining unit (180) or includes some

A leak diagnosis system according to an embodiment of the present disclosure is a system for diagnosing a leak in the urea pump line 160 provided in an exhaust gas after-treatment device for a diesel engine.

The engine 100 is configured to provide a driving force to a vehicle, wherein the vehicle may be, for example, a vehicle using diesel as a fuel, but is not limited thereto. The engine 100 provides driving power to the vehicle by burning fuel, and exhaust gas is generated from the engine 100 in this process.

These exhaust gases contain a large amount of harmful components such as nitrogen oxides (NOx), and in particular, in the case of a diesel vehicle, a large amount of nitrogen oxide may be emitted compared to a gasoline vehicle, so nitrogen oxides are reduced to prevent environmental pollution. I need this. Therefore, the leak diagnosis system according to an embodiment of the present disclosure may be configured such that exhaust gas generated from the engine 100 flows into the post-processing unit 120 through an exhaust gas inlet pipe 110 . have.

The post-processing unit 120 is configured to reduce the nitrogen oxide concentration of the exhaust gas generated from the engine 100 by using urea. The post-processing unit 120 may include a Selective Catalyst Reduction (SCR module, not shown) configured to cause a catalytic reaction between the exhaust gas and urea.

Using a catalytic reaction, nitrogen oxides in the exhaust gas can be reduced to nitrogen (N2) and water (H2O), thereby lowering the nitrogen oxide concentration in the exhaust gas. Exhaust gas after the catalytic reaction has occurred in the post-processing unit 120 may be discharged to the outside through an exhaust gas outlet pipe 130 .

The first concentration sensor 115 measures the nitrogen oxide concentration of the exhaust gas before passing through the post-processing unit 120 . That is, the first concentration sensor 115 measures the nitrogen oxide concentration of the exhaust gas before the exhaust gas generated from the engine 100 flows into the post-processing unit 120 . For this, the first concentration sensor 115 may be configured to be included in the exhaust gas inlet pipe 110 . In addition, the concentration value of the exhaust gas measured by the first concentration sensor 115 may be transmitted to the leak determination unit (180).

The second concentration sensor 135 measures the nitrogen oxide concentration of the exhaust gas that has passed through the post-processing unit 120 . That is, the second concentration sensor 135 passes through the post-processing unit 120 to measure the nitrogen oxide concentration of the exhaust gas having a relatively low nitrogen oxide concentration. To this end, the second concentration sensor 135 may be configured to be included in the exhaust gas discharge pipe 130 . In addition, the concentration value of the exhaust gas measured by the second concentration sensor 135 may be transmitted to the leak determination unit (180).

The configuration of the first concentration sensor 115 and the second concentration sensor 135 and the method in which the first concentration sensor 115 and the second concentration sensor 135 measure the nitrogen oxides in the exhaust gas are, Since it is well known to those skilled in the art, a detailed description thereof will be omitted.

A urea aqueous solution obtained by dissolving urea in water is stored in the urea tank 140 . In order to prevent the urea aqueous solution stored in the urea tank 140 from freezing, the urea tank 140 may include an insulating material.

In addition, the urea tank 140 may include a capacity sensor (capacity sensor, not shown) for measuring the capacity of the urea aqueous solution remaining therein. The capacity sensor may be made of an ultrasonic sensor, an infrared sensor, etc., and may be installed on the bottom surface of the urea tank 140 for capacity measurement, but is not necessarily limited thereto. In addition, the capacitance value measured by the capacitance sensor may be transmitted to the water leakage determination unit (180).

The urea pump 150 is configured to withdraw and pressurize the urea aqueous solution in the urea tank 140 . Referring to FIG. 1 , the urea pump 150 is configured to be disposed at the upper end of the urea tank 140 , but as long as the urea aqueous solution stored in the urea tank 140 can be withdrawn and pressurized, the urea pump ( 150) is not necessarily limited to the position shown in FIG. 1 .

In addition, the urea pump 150 may be provided with a pressure sensor (pressure sensor, 155) for measuring the pressure of the pressurized urea aqueous solution. In FIG. 1 , the pressure sensor 155 is illustrated as being installed in the urea pump 150 , but the present invention is not limited thereto, and may be installed on the pump line 160 . In addition, the pressure value of the urea aqueous solution measured by the pressure sensor 155 may be transmitted to the leak determination unit 180 . Since the configuration of the pressure sensor 155 and the method in which the pressure sensor 155 measures the pressure of the urea aqueous solution are well known to those skilled in the art related to the exhaust gas post-treatment device, a detailed description thereof will be omitted.

The dosing module 170 is configured to spray the pressurized urea aqueous solution to the post-processing unit 120 . More specifically, the dosing module 170 may receive a high-pressure urea aqueous solution by a pump line 160 to be described later, and may spray the supplied urea aqueous solution toward the exhaust gas inside the post-processing unit 120 . .

The pump line 160 is configured to deliver the urea aqueous solution pressurized by the urea pump 150 to the dosing module 170 . When the pump line 160 delivers the pressurized aqueous urea solution to the dosing module 170 , the dosing module 170 may spray the urea aqueous solution. However, when a leak occurs in the pump line 160, the pressure of the urea aqueous solution flowing through the pump line 160 is lowered, and accordingly, the urea aqueous solution may not be properly sprayed. Therefore, when a leak occurs in the pump line 160, a leak diagnosis system capable of detecting this is required.

The water leak determination unit 180 is based on the difference between the concentration values measured by the first concentration sensor 115 and the second concentration sensor 135 and whether the pressure value measured by the pressure sensor 155 increases, the pump line ( 160) is configured to determine whether leakage occurs. More specifically, whether the difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is less than the reference value and whether the pressure value of the urea aqueous solution measured by the pressure sensor 155 increases Based on whether or not, it is possible to determine whether leakage of the pump line 160 has occurred.

When the difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is equal to or greater than the reference value, the water leak determination unit 180 may determine that no water leakage has occurred in the pump line 160 . Here, the reference value means a minimum concentration reduction value expected when the nitrogen oxide concentration of the exhaust gas passing through the post-processing unit 120 decreases. Therefore, when the difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is equal to or greater than the reference value, the concentration reduction of nitrogen oxide is normally being made, so the water leak determination unit 180 is the pump line It may be determined that there is no leakage in 160, or it may not be determined whether leakage has occurred.

However, the aforementioned reference value is not a fixed value, and may be changed according to the magnitude of the concentration value received from the first concentration sensor 115 . That is, when the concentration value received from the first concentration sensor 115 is large, the reference value may be increased, and when the concentration value received from the first concentration sensor 115 is small, the reference value may also be decreased.

When the difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is less than the reference value, it means that the urea aqueous solution is not properly sprayed, and in this case, the leak determination unit 180 is It can be determined whether the pressure value of the urea aqueous solution measured by the pressure sensor 155 increases.

When the pressure value of the urea aqueous solution measured by the pressure sensor 155 increases, the water leak determination unit 180 may determine that no water leakage has occurred in the pump line 160 or may not determine whether water leakage occurs. That is, since the urea aqueous solution pressurized by the urea pump 150 is delivered to the dosing module 170 through the pump line 160 , when the pressure value of the urea aqueous solution measured by the pressure sensor 155 increases, the pump It is preferred that the leak in line 160 is not considered to have occurred.

However, when the pressure value of the urea aqueous solution measured by the pressure sensor 155 does not increase, the leak determination unit 180 may determine that a leak has occurred in the pump line 160 . When a leak occurs in the pump line 160 , even if the urea pump 150 presses the urea aqueous solution, the pressure of the urea aqueous solution drops while the urea aqueous solution is delivered to the dosing module 170 through the pump line 160 .

Therefore, the leak determination unit 180 has a difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is less than the reference value, and the pressure value of the aqueous urea solution measured by the pressure sensor 155 . If this does not increase, it can be determined that a leak has occurred in the pump line 160 .

The leak diagnosis system according to an embodiment of the present disclosure can diagnose a leak in the pump line 160 that delivers the urea aqueous solution by including the above configuration. The conventional exhaust gas post-treatment device was equipped with a concentration sensor for measuring the concentration of nitrogen oxide before and after reducing the concentration of nitrogen oxide and a pressure sensor for measuring the pressure of the urea aqueous solution. there was no way In other words, it was possible to recognize the situation where the problem occurred in the post-treatment device because the reduction in the concentration of nitrogen oxide did not occur, but whether the problem occurred in any of the various components included in the post-processing device, in particular, whether a leak occurred in the pump line. It could not be determined whether

The leak diagnosis system according to an embodiment of the present disclosure can diagnose a leak in the pump line 160 without adding any more sensors by using a sensor provided in a conventional exhaust gas post-processing device.

That is, the leak determination unit 180 receives the nitrogen oxide concentration value of the exhaust gas from the first concentration sensor 115 and the second concentration sensor 135, and receives the pressure value of the urea aqueous solution from the pressure sensor 155. , it is possible to determine whether leakage of the pump line 160 occurs. Therefore, the leak diagnosis system according to an embodiment of the present disclosure has the advantage of diagnosing whether or not a leak has occurred in the pump line 160 without additional cost.

Hereinafter, a configuration for more accurately determining whether leakage occurs in the pump line 160 will be described.

Leakage determination unit 180, based on the concentration value measured by the first concentration sensor 115, for more accurate determination of whether leakage occurs, the amount of urea aqueous solution required for reducing the concentration of nitrogen oxide is less than or equal to a preset amount It can be determined whether or not

In this case, when it is determined that the amount of the urea aqueous solution required for reducing the concentration of nitrogen oxides is less than or equal to a preset amount, the leak determination unit 180 may be configured to determine whether or not a leak occurs in the pump line 160 . Here, the preset amount may be set using a look-up table or a separate algorithm based on the concentration value measured by the first concentration sensor 115 .

This is to determine whether leakage of the pump line 160 occurs when the injection amount of the urea aqueous solution is relatively small. When the injection amount of the urea aqueous solution is small, it is easier to determine the pressure increase of the urea aqueous solution by the urea pump 150 .

Therefore, when the concentration value received from the first concentration sensor 115 is small, for example, when the nitrogen oxide concentration of the exhaust gas discharged from the engine 100 is less than about 200 ppm, the water leak determination unit 180 is also a relatively aqueous solution of urea. In this case, it is possible to determine whether leakage occurs in the pump line 160 or not. On the other hand, the preset amount may be set to the amount of the urea aqueous solution required for nitrogen oxide reduction when the nitrogen oxide concentration of the exhaust gas discharged from the engine 100 is less than about 200 ppm.

On the other hand, when the nitrogen oxide concentration of the exhaust gas discharged from the engine 100 is low, when the revolution per minute (RPM) of the engine is low, when the fuel injection amount is small, when the temperature of the cylinder is low, etc. can

When the injection of the urea aqueous solution is required a lot, the urea pump 150 presses the urea aqueous solution to a relatively higher pressure and supplies it to the pump line 160 . When the high-pressure urea aqueous solution is injected by the dosing module 170 through the pump line 160, the pressure of the urea aqueous solution may be reduced in the process of spraying the urea aqueous solution even in a situation where all configurations are normal. This pressure drop may be a phenomenon that may occur as a result of spraying a high-pressure urea aqueous solution, not due to a leak in the pump line 160, even when all configurations are normal.

In addition, in a situation in which a relatively high-pressure urea aqueous solution is sprayed, the pressure of the urea aqueous solution may be partially increased by the urea pump 150 even though a leak has occurred in the pump line 160 . Therefore, in order to more accurately determine the occurrence of water leakage in the pump line 160, the water leakage determination unit 180 determines that the amount of the urea aqueous solution required for reducing the concentration of nitrogen oxide is less than or equal to a preset amount of the pump line 160. It may be configured to determine whether leakage occurs.

In addition, the leak diagnosis system according to an embodiment of the present disclosure may further include an engine failure determining unit (not shown) for determining whether the engine 100 has failed. In this case, when the engine 100 is determined to be normal by the engine failure determining unit, the water leak determination unit 180 may determine whether water leakage occurs in the pump line 160 .

When the engine 100 fails, the amount of exhaust gas and the concentration of nitrogen oxide may be rapidly changed, and accordingly, the pressure and capacity of the urea aqueous solution injected to the post-processing unit 120 may also be rapidly changed. Accordingly, the water leak determination unit 180 may be configured to determine whether water leakage occurs in the pump line 160 when the engine 100 is determined to be normal by the engine failure determination unit.

In addition, the leak diagnosis system according to an embodiment of the present disclosure may further include a pump failure determining unit (not shown) for determining whether the urea pump 150 has failed. In this case, when it is determined that the urea pump 150 is normal by the pump failure determining unit, the water leak determination unit 180 may determine whether water leakage occurs in the pump line 160 .

When the urea pump 150 fails, when the urea aqueous solution stored in the urea tank 140 is withdrawn and pressurized, the pressure of the urea aqueous solution may be rapidly changed. Accordingly, the water leak determination unit 180 may be configured to determine whether water leakage occurs in the pump line 160 when the urea pump 150 is determined to be normal by the pump failure determination unit.

In addition, when the capacity value of the urea aqueous solution measured by the capacity sensor is equal to or greater than a preset value, the water leak determination unit 180 may determine whether water leakage occurs in the pump line 160 . Here, the preset value refers to a capacity value sufficient to allow the urea pump 150 to generate sufficient pressure.

When there is almost no urea aqueous solution remaining inside the urea tank 140, even if the urea pump 150 withdraws and pressurizes the urea aqueous solution, the pressure of the urea aqueous solution may decrease without increasing. Therefore, when the capacity value of the urea aqueous solution measured by the capacity sensor is equal to or greater than a preset value, the leak determination unit 180 may be configured to determine whether water leakage occurs in the pump line 160 .

The engine failure determination unit, the pump failure determination unit, and the capacity sensor described above are provided in the conventional exhaust gas after-treatment device and vehicle, and the leak diagnosis system according to an embodiment of the present disclosure is similarly provided without installing a separate sensor. It can be determined whether a leak occurs in the pump line 160 .

Hereinafter, a leak diagnosis method according to an embodiment of the present disclosure will be described based on the foregoing.

2 is a flowchart illustrating a leak diagnosis method according to an embodiment of the present disclosure.

In the leak diagnosis method according to an embodiment of the present disclosure, a concentration value of nitrogen oxide is received from the first concentration sensor 115 ( S200 ). That is, the leak determination unit 180 receives the nitrogen oxide concentration value of the exhaust gas generated from the engine 100 from the first concentration sensor 115 .

The pressure value of the pressurized urea aqueous solution is received from the pressure sensor 155 (S210). When the urea pump 150 draws out and pressurizes the urea aqueous solution stored in the urea tank 140, and the urea aqueous solution is delivered to the dosing module 170 using the pump line 160, the pressure sensor 155 is pressurized. Measure the pressure value of the urea aqueous solution. In this case, the leak determination unit 180 may receive the pressure value of the urea aqueous solution from the pressure sensor 155 .

The concentration value of nitrogen oxide is received from the second concentration sensor 135 (S220). That is, the leak determination unit 180 receives the nitrogen oxide concentration value of the exhaust gas that has passed through the post-processing unit 120 from the second concentration sensor 135 . In a normal case, since the nitrogen oxide concentration of the exhaust gas that has passed through the post-processing unit 120 should decrease, the nitrogen oxide concentration measured by the second concentration sensor 135 is the nitrogen oxide concentration measured by the first concentration sensor 115 . is lower than the concentration of

It may be determined whether the amount of the urea aqueous solution required for reducing the concentration of nitrogen oxide is less than or equal to a preset amount (S230). Here, the description of the preset amount is the same as described above, and thus will be omitted. Based on the concentration value received from the first concentration sensor 115, the leak determination unit 180 may determine whether the amount of the urea aqueous solution required for reducing the concentration of nitrogen oxide is less than or equal to a preset amount.

When the amount of the urea aqueous solution required for reducing the concentration of nitrogen oxides exceeds a preset amount, the leak determination unit 180 may no longer diagnose the leak, and repeat the above-described process. A detailed description thereof will be omitted since it is the same as described above.

When the amount of urea aqueous solution required for reducing the concentration of nitrogen oxide is less than or equal to a preset amount, the leak determination unit 180 determines that the difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is a reference value. It can be determined whether it is less than (S240). Here, a description of the reference value is omitted since it is the same as described above. However, the leak determination unit 180 receives from the first concentration sensor 115 and the second concentration sensor 135 regardless of whether the amount of the urea aqueous solution required for reducing the concentration of nitrogen oxide is less than or equal to a preset amount It may be determined whether the difference between the concentration values is less than a reference value.

When the difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is equal to or greater than the reference value, the nitrogen oxide concentration of the exhaust gas is normally reduced, so the water leak determination unit 180 further performs the leak diagnosis. Without further progressing, the above-described process is repeated.

When the difference between the concentration values received from the first concentration sensor 115 and the second concentration sensor 135 is less than the reference value, it is determined whether the pressure value of the aqueous urea solution received from the pressure sensor 155 increases (S250) . When the pressure value of the aqueous urea solution received from the pressure sensor 155 increases, since the leak in the pump line 160 does not occur, the leak determination unit 180 does not proceed with the leak diagnosis any longer, and the above-described process to proceed repeatedly. However, since the concentration of nitrogen oxide is not reduced, the driver is informed that there is an abnormality in the exhaust gas post-processing device using a separate notification means, for example, a display device, a wireless communication device, etc. before repeating the above process. may inform.

When the pressure value of the aqueous urea solution received from the pressure sensor 155 does not increase, the leak determination unit 180 determines that a leak has occurred in the pump line 160 (S260).

Since the leak diagnosis method according to an embodiment of the present disclosure includes the above process, it is possible to determine whether a leak occurs in the pump line 160 without installing a separate sensor.

On the other hand, although not shown in FIG. 2 , the leak diagnosis method according to an embodiment of the present disclosure includes a process in which the water leak determination unit 180 receives information on whether or not the engine has failed from the engine failure determination unit before the process S240. may include more. In this case, the process S240 may be performed when the engine 100 is determined to be normal by the engine failure determining unit.

In addition, the leak diagnosis method according to an embodiment of the present disclosure may further include, before the step S240, the step of the water leak determining unit 180 receiving information on whether the pump is faulty from the pump failure determining unit. In this case, the process S240 may be made when it is determined that the urea pump 150 is normal by the pump failure determining unit.

In addition, the leak diagnosis method according to an embodiment of the present disclosure may further include, before the process S240, the leak determination unit 180 receives the capacity value of the urea aqueous solution remaining in the urea tank 140 from the capacity sensor. can In this case, the process S240 may be made when the capacity value of the urea aqueous solution received from the capacity sensor is equal to or greater than a preset value. Here, the preset value is the same as described above, and thus is omitted.

The above description is merely illustrative of the technical idea of this embodiment, and a person skilled in the art to which this embodiment belongs may make various modifications and variations without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present embodiment.

100: engine 110: exhaust gas inlet pipe
115: first concentration sensor 120: post-processing unit
130: exhaust gas discharge pipe 135: second concentration sensor
140: urea tank 150: urea pump
155: pressure sensor 160: pump line
170: dosing module 180: leak determination unit

Claims (10)

an after treatment unit configured to reduce a nitrogen oxide (NOx) concentration of exhaust gas generated from an engine by using urea;
a first concentration sensor for measuring the nitrogen oxide concentration of the exhaust gas before passing through the post-processing unit;
a second concentration sensor for measuring the nitrogen oxide concentration of the exhaust gas that has passed through the post-processing unit;
a urea tank in which an aqueous urea solution is stored;
a urea pump configured to withdraw and pressurize the urea aqueous solution in the urea tank, and have a pressure sensor for measuring the pressure of the pressurized urea aqueous solution;
a dosing module configured to spray the pressurized urea aqueous solution into the post-processing unit;
a pump line configured to deliver the urea aqueous solution pressurized by the urea pump to the dosing module; and
A leak determining unit configured to determine whether water leakage has occurred in the pump line based on a difference between the concentration values measured by the first concentration sensor and the second concentration sensor and whether the pressure value measured by the pressure sensor increases. unit)
A leak diagnosis system comprising a. The method of claim 1,
The leak determination unit,
Based on the concentration value measured by the first concentration sensor, when it is determined that the amount of the urea aqueous solution required for reducing the concentration of nitrogen oxide is less than a preset amount, configured to determine whether leakage of the pump line occurs Leakage diagnosis system characterized by. The method of claim 1,
Further comprising an engine failure determining unit (engine failure determining unit) to determine whether the failure of the engine,
The leak determination unit,
When the engine failure determination unit determines that the engine is normal, the leak diagnosis system is configured to determine whether water leakage occurs in the pump line. The method of claim 1,
Further comprising a pump failure determining unit (pump failure determining unit) for determining whether the failure of the urea pump,
The leak determination unit,
When it is determined by the pump failure determining unit that the urea pump is normal, the leak diagnosis system is configured to determine whether water leakage occurs in the pump line. The method of claim 1,
The urea tank is
Further comprising a capacity sensor (capacity sensor) for measuring the capacity of the urea aqueous solution remaining inside,
The leak determination unit,
When the capacity value of the urea aqueous solution measured by the capacity sensor is greater than or equal to a preset value, the leak diagnosis system is configured to determine whether water leakage occurs in the pump line. In the method for diagnosing a leak by a leak determination unit of an exhaust gas post-treatment device,
Receiving the nitrogen oxide concentration value of the exhaust gas generated from the engine from the first concentration sensor;
When the urea pump draws out and pressurizes the urea aqueous solution stored in the urea tank, and the urea aqueous solution is delivered to the dosing module using a pump line, the pressure value of the pressurized urea aqueous solution is received from the pressure sensor included in the urea pump process;
receiving a nitrogen oxide concentration value of the exhaust gas that has passed through the post-processing unit configured to reduce the nitrogen oxide concentration of the exhaust gas from a second concentration sensor;
determining whether a difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value;
If the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value, determining whether the pressure value of the aqueous urea solution received from the pressure sensor increases; and
When the pressure value of the aqueous urea solution received from the pressure sensor does not increase, the process of determining that a leak has occurred in the pump line
A leak diagnosis method comprising a. 7. The method of claim 6,
Prior to the process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
Based on the concentration value received from the first concentration sensor, further comprising the step of determining whether the amount of the urea aqueous solution required for reducing the concentration of the nitrogen oxide is less than a preset amount,
The process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
A leak diagnosis method, characterized in that it is made when the amount of the urea aqueous solution required to reduce the concentration of the nitrogen oxide is less than a predetermined amount. 7. The method of claim 6,
Prior to the process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
Further comprising the step of receiving information on whether the engine failure from the engine failure determination unit for determining whether the engine failure,
The process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
The leak diagnosis method, characterized in that it is performed when the engine failure determination unit determines that the engine is normal. 7. The method of claim 6,
Prior to the process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
Further comprising the step of receiving information on whether the pump failure from the pump failure determination unit for determining whether the failure of the urea pump,
The process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
The leak diagnosis method, characterized in that made when it is determined that the urea pump is normal by the pump failure determining unit. 7. The method of claim 6,
Prior to the process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
Further comprising the step of receiving a capacity value of the urea aqueous solution from a capacity sensor for measuring the capacity of the urea aqueous solution remaining inside the urea tank,
The process of determining whether the difference between the concentration values received from the first concentration sensor and the second concentration sensor is less than a reference value,
Leakage diagnosis method, characterized in that made when the capacity value of the urea aqueous solution received from the capacity sensor is greater than or equal to a preset value.

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