KR102534129B1 - Urea water injection system and method using the same - Google Patents

Abstract

The present invention relates to a urea solution injection system, which minimizes an error range and to a method using the same. The urea solution injection system comprises: a urea solution tank (110) for storing a urea solution; a urea solution flow path (120) including first and second urea solution flow paths (121, 122); an airflow path (140) with a pressure sensor (143); and a control module (150) for operating a urea solution pump (123) and an air regulator (141).

Description

Urea water injection system and method using the same {Urea water injection system and method using the same}

The present invention relates to a urea water injection system and a method using the same.

In general, nitrogen oxides (NOx), particulate matter (PM), and particulate dust contained in exhaust gas emitted from diesel engine vehicles cause photochemical reactions in the atmosphere to cause smog and destroy ozone in the atmosphere. pointed out as a factor.

Accordingly, up to Euro 5, the European vehicle exhaust gas regulation standard, the exhaust gas reduction system of a diesel engine was applied with an exhaust gas recirculation (EGR) system and a diesel particulate filter (DPF) device to meet the regulatory standards.

However, as nitrogen oxide emission standards are further strengthened in Euro 6, there is a limit to meeting the regulatory standards with existing systems and devices. ) system (hereinafter referred to as 'SCR system') must be applied.

The SCR system is named selective catalytic reduction in the sense that reducing agents including urea, ammonia, carbon monoxide and hydrocarbons (HC) react better with nitrogen oxides among oxygen and nitrogen oxides. For example, a conventional SCR system is provided with a urea water tank and an injector to effectively purify nitrogen oxides by injecting a reducing agent such as urea water into exhaust gas flowing through an engine exhaust pipe.

The SCR system is a device that separates nitrogen oxides (NOx) into nitrogen (N), water vapor (H ₂ O), and carbon dioxide (CO ₂ ) by spraying urea to the SCR carrier and catalyst. role is important. Urea water is mixed with 32.5% of urea and 67.5% of water, and crystallization begins when it comes into contact with air or at temperatures above 110℃, and freezes at -11℃ below, making it a sensitive material to the external environment.

Therefore, since the urea water in the connection hose between the urea water tank and the injection device in the vehicle is not always filled with urea water depending on the attachment position and driving conditions, etc. And the part where urea water is sprayed and confirmed from the urea water nozzle is important.

Until now, the confirmation of urea water intake and urea water injection is determined by measuring the pressure at which urea water is discharged from the urea water pump. The condition cannot be accurately diagnosed.

(Patent Document 1) Korean Patent Publication No. 10-2020-0104127

(Patent Document 2) Korean Patent Registration No. 10-1074050

The present invention has been made to solve the above problems.

An object of the present invention is to provide a technique for determining the state of suction and nozzles that can minimize the error range for the pressure value of the urea water passage and maintain the number of urea up to the injection device to obtain optimal efficiency.

In addition, the present invention is a technology that replaces the existing expensive urea solution-only sensor, and is intended to provide a technology for monitoring and diagnosing suction, normal injection, and nozzle clogging of a urea solution injection device using a pressure sensor.

One embodiment of the present invention for solving the above problems is a urea water injection system for supplying urea water to a selective catalytic reduction (SCR) of an exhaust gas reduction device, and a urea water tank in which urea water is stored. (110); As a urea water flow path 120 for supplying urea water from the urea water tank 110 using the urea water pump 123, the urea water in the urea water tank 110 is returned to the urea water tank 110. A urea water passage 120 including a first urea water passage 121 for circulation and a second urea water passage 122 for supplying urea water to the urea water injection device 130; As an air flow path 140 for supplying air to the urea water nozzle 142 connected to the urea water injection device 130 using the air regulator 141, the pressure of the fluid discharged from the urea water nozzle 142 An air flow path 140 equipped with a pressure sensor 143 for sensing; And a control module 150 for operating the urea water pump 123 and the air regulator 141 in a preset manner, in a first mode in which the urea water pump 123 and the air regulator 141 are operated together. A control module 150 for obtaining a pressure value of the fluid discharged from the urea water nozzle 142 at a predetermined cycle after calculating a reference pressure using the pressure sensor 143; Including, the control module 150 calculates a normal range using the calculated reference pressure, but when the pressure value of the fluid exceeds the normal range, the normal of the urea water pump 123 It provides a urea water injection system that determines the discharge state.

The air passage 140 is provided with an air valve 144 for controlling the air supplied from the air regulator 141, and at the rear end of the air valve 144, the first element water passage 121 and the three-way air valve 144 are provided. It further includes an air branch flow path 160 connected through a valve (3-Way Valve) 124, and the three-way valve 124 has a first side connected to the second element water flow path 122, , the second side may be connected to the first element water passage 121, and the third side may be connected to the air branch passage 160.

In the first mode, in a state in which the air valve 144 is closed, after the urea water pump 123 is operated with the first output for a preset time, the urea water pump 123 outputs the first output. It operates with a lower second output, the air valve 144 is opened, air is supplied from the air regulator 141, and the three-way valve 124 is connected to the first side for a preset time. A pressure maintained during may be determined as the reference pressure.

The control module 150, in the first mode, when the pressure value of the fluid is less than the normal range, may be set to repeatedly perform the first mode a preset number of times.

The control module 150 operates in a second mode in which urea water is injected through the urea water injector 130, and in the second mode, the maximum number of urea sprayed from the urea water injector 130 Based on the pressure value for the injection amount, the maximum pressure is calculated, and clogging of the urea water passage 120 can be determined using the maximum pressure.

In the second mode, when the normal range determined in the first mode is exceeded; Alternatively, if the maximum pressure is calculated in plurality, but the slope values of the Nth maximum pressure and the N+1th maximum pressure increase; It can be determined that the urea water passage 120 is clogged.

On the other hand, the present invention is a method for controlling the above-described urea water injection system, (a) in a state in which the air valve 144 is closed, the urea water pump 123 is operated with the first output for a preset time, circulating the urea water in the urea water tank 110 along the first urea water flow path 121 (S110); (b) the air valve 144 is opened, air is supplied from the air regulator 141, and the urea water pump 123 is operated with a second output smaller than the first output, wherein the air flow path The air branch passage 160 branching from the air passage 140 and the three-way valve 124 connected to the first and second element water passages 121 and 122 are controlled to communicate with the second element water passage 122, , The urea water and air in the urea water tank 110 are discharged to the urea water nozzle 142, step (S120); (c) obtaining a pressure value of the fluid discharged from the urea water nozzle 142 using the pressure sensor 143, and calculating a reference pressure using the pressure value in a preset method ( S130); And (d) comparing the reference pressure calculated in step (c) with the pressure value of the fluid discharged from the urea water nozzle 142 to determine the normal discharge state of the urea water pump 123 (S140 ); In the step (d), the control module 150 calculates a normal range using the reference pressure, but when the pressure value of the fluid exceeds the normal range, the urea water pump Provides a method for determining the normal discharge state of (123).

After the step (d), (e) operating in a second mode in which urea water is injected through the urea water injector 130, wherein in the second mode, the urea water injector 130 is injected Calculating a maximum pressure based on a pressure value for a maximum injection amount of urea water, and determining clogging of the urea water passage 120 using the maximum pressure (S150); may further include.

The present invention can provide a technique for suction and nozzle condition check that minimizes the error range for the pressure value of the urea water passage and maintains the number of urea up to the injection device to obtain optimal efficiency.

In addition, the present invention is a technology that replaces the existing expensive urea solution-only sensor, and it is possible to monitor and diagnose suction, normal injection, and nozzle clogging of the urea solution injection device using a pressure sensor.

1 is a schematic diagram showing a flow path of a urea water injection system according to the present invention.
2 is a conceptual diagram showing a control module of the urea water injection system according to the present invention.
Figure 3A is a schematic diagram showing a first step of the first mode of the urea water injection system of the present invention in Figure 2.
Figure 3B is a schematic diagram showing the second step of the first mode of the urea water injection system of the present invention in Figure 2.
Figure 4 is a schematic view of the operation of the urea water pump and the air regulator of FIG.
FIG. 5 is a graph showing pressure values in each section based on FIG. 4 .
6 is experimental data by the present applicant, and is a pressure value measured by turning on/off the air valve for 1,000 seconds to check the state of the urea water nozzle.
7 is a graph showing an example in which the urea water nozzle or the urea water passage is determined to be in an abnormal state.
8 is a graph showing another example of an abnormal state of a urea water nozzle or a urea water passage.
9 is a flow chart of a method using a urea water injection system according to the present invention.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, only these embodiments are intended to complete the disclosure of the present invention, and are common in the art to which the present invention belongs. It is provided to fully inform the person skilled in the art of the scope of the invention, and the invention is only defined by the scope of the claims.

Terminology used herein is for describing the embodiments and is not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprises" and/or "comprising" does not exclude the presence or addition of one or more other elements other than the recited elements. Like reference numerals throughout the specification refer to like elements, and “and/or” includes each and every combination of one or more of the recited elements. Although "first", "second", etc. are used to describe various components, these components are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first element mentioned below may also be the second element within the technical spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings commonly understood by those skilled in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

Hereinafter, a urea water injection system according to an embodiment of the present invention will be described with reference to the drawings.

The urea water injection system according to the present invention may be understood as a system for supplying urea water to a selective catalytic reduction (SCR) of an exhaust gas reduction device. In the present application, a structure including the urea water injection device 130 and a vehicle controller (ECU) (not shown) will be described as an example. In addition, the present invention will be described on the premise that the urea water injection system according to the present invention is applied to a vehicle, but the present invention is not limited thereto and can be applied to all devices/systems to which the present invention is applicable.

The engine of a vehicle burns a mixture of fuel and air to convert chemical energy into mechanical energy. Air is introduced into the engine through the intake manifold, and the exhaust gas generated in the combustion process is collected and discharged to the outside through the exhaust manifold. The exhaust pipe is connected to the exhaust manifold of the engine to discharge exhaust gas to the outside of the vehicle. return to

The urea water injection device 130 pumps the urea water stored in the urea water tank 110 at a constant pressure through the urea water pump 123 according to the applied operation signal to create a urea water nozzle (also called an 'injector') through the exhaust pipe.

Nitrogen oxides (NOx) contained in exhaust gas are converted into nitrogen (N2) and water (H2O) harmless to the human body through chemical and catalytic processes that occur when meeting urea water. Here, the urea water is a chemical substance prepared by mixing urea and water, and the urea water injected into the exhaust gas decomposes into ammonia (NH3), and the decomposed ammonia is used as a reducing agent for nitrogen oxides.

A particulate filter is further mounted on the exhaust pipe to collect soot included in the exhaust gas. As a result, the exhaust gas generated from the engine passes through the particulate filter and the urea water injection device 130 sequentially, and harmful components in the exhaust gas can be removed. The vehicle controller collects driving information according to the operation of the vehicle through various sensors and devices, and controls the overall operation for reducing exhaust gas based on this. The operation information may include an amount of nitrogen oxides in the exhaust gas required to purify the exhaust gas, an engine rotation speed, a fuel injection amount, a temperature of the SCR catalyst, and an exhaust flow rate.

The vehicle controller measures the amount of nitrogen oxides contained in the exhaust gas flowing through the exhaust pipe through at least one nitrogen oxide sensor, and determines the supply amount of urea water based on the measured amount. And, it operates as an upper controller that applies an operation command to the urea water supply device so that the urea water can be supplied according to the supply amount of the urea water.

As an example, the vehicle controller may measure the amount of nitrogen oxides from sensors installed at the front and rear ends of the SCR, and correct the urea solution supply amount according to the deviation. At this time, the vehicle controller may correct the urea water supply amount by referring to the engine rotation speed, the fuel injection amount, the SCR catalyst temperature, and the exhaust flow rate according to the driving of the vehicle.

Meanwhile, the control module 150 of the present application may be configured in an integrated form with a vehicle controller. However, in the present application, the control module 150 is separately defined and described in order to separately describe the functions of the SCR.

1 and 2, the urea water injection system according to the present invention includes a urea water tank 110, a urea water flow path 120, a urea water injection device 130, an air flow path 140, and a control module 150. and an air branch passage 160.

The urea water tank 110 is a tank in which urea water is stored or stored. As an airtight container, it stores the number of urea injected from the outside, and although not shown in the drawings, it may include a quantity sensor and a temperature sensor.

The urea water passage 120 is a passage through which urea water is supplied from the urea water tank 110 using the urea water pump 123 .

The urea receiving passage 120 may be divided into first and second urea receiving passages 121 and 122 . The first urea water passage 121 means a circulation passage through which the urea water in the urea water tank 110 is circulated back to the urea water tank 110 . The second urea water passage 122 is a passage through which urea water in the urea water tank 110 is supplied to the urea water nozzle 142 .

At this time, the first and second urea water passages 121 and 122 are connected by a 3-way valve 124. In addition, the three-way valve 124 is connected to the air branch passage 160.

Specifically, the first side of the three-way valve 124 is connected to the second urea water passage 122, the second side is connected to the first urea water passage 121, and the third side is connected to the air branch passage 160 Connected to, the three-way valve 124 is an electronic valve and is automatically controlled by the control module 150.

The air passage 140 is configured to supply air to the urea water nozzle 142 connected to the urea water injection device 130 using the air regulator 141 . If described based on the direction in which air flows, the air regulator 141 - air valve 144 - pressure sensor 143 - urea water nozzle 142 may be arranged in order. The air valve 144 controls air supplied from the air regulator 141. Not only can the air supply be opened and closed, but also the air supply amount can be controlled. The air valve 144 is an electronic valve, and may be automatically controlled by the control module 150.
As shown in FIG. 1, the air branch passage 160 is connected to the rear end of the air valve 144 and is connected to the three-way valve 124 described above. The air passage 140 is formed in a shape merged with the second urea water passage 122 at the rear end of the pressure sensor 143, and the urea water nozzle ( 142), urea water or air may be supplied. The pressure sensor 143 is configured to sense both the pressure value of air and the combined pressure value of urea water, including the pressure value of air. A state in which air and urea water are added will be defined and described as 'fluid' hereinafter.

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Meanwhile, an orifice 145 may be provided in the middle of the air passage 140 . The orifice 145 performs a function of injecting appropriate air into the urea water nozzle 142 . In addition, a first non-return valve 146 may be provided at the rear end of the orifice 145 . As a kind of check valve, it is possible to prevent the urea water from flowing backward into the air passage 140 .

A second non-return valve 125 may be provided at a rear end of the second urea water passage 122 . The second check valve 125 serves to prevent back flow of the urea water pump 123 . Since the first and second non-return valves 146 and 125 allow only one-way flow of fluid, it is specified in advance that all known configurations performing these functions may be used.

The urea water nozzle 142 may be understood as a configuration for atomizing urea water, and may be understood as an end of a section where the air flow path 140 and the second urea water flow path 122 converge. When the urea water nozzle 142 is clogged, an error code may be generated in the vehicle controller as the urea water is not properly supplied to the urea water injection device 130 .

Hereinafter, mode operation using the urea water injection system according to the present invention will be described with reference to FIGS. 2 to 8 .

The control module 150 may operate the urea water pump 123 and the air regulator 141 in a first mode or a second mode.

The 'first mode' may be understood as a mode for checking whether urea water is normally discharged when urea water is supplied from the urea water tank 110 to the urea water pump 123 and the urea water pump 123 is driven.

Referring to FIG. 4, in the process of supplying urea water from the urea water tank 110 to the urea water pump 123, only the urea water pump 123 is driven while the air valve 144 is closed as in step ⓐ. controlled to do When the urea water pump 123 is driven, the flow of urea water from the urea water tank 110 to the urea water pump 123 means a circulation in which the urea water flows into the urea water tank 110 again.

At this time, since urea water must be filled in the air-filled portion between the urea water tank 110 and the urea water pump 123, proper operation and time of the urea water pump are required. This can be classified as a 'suction section of the number of elements'.

Then, an operation of minimizing the driving of the urea water pump 123 and driving it together with air is performed. The three-way valve 124 is switched to block the flow to the first urea water passage 121 . The three-way valve 124 is switched to flow into the second urea water passage 122, so that when air and urea water are supplied to the urea water nozzle 142 together, the pressure value is set to be sensed. At this time, the pressure value is sensed at a predetermined cycle, and real-time sensing may be performed.

Referring to FIG. 5 together, since the injection amount of fluid is large in the urea water suction section, the pressure value of the fluid may temporarily increase significantly. A pressure value at which the initially temporarily increased pressure is maintained after a certain period of time may be determined as the 'reference pressure'.

In this way, after the reference pressure is determined, a normal range is set based on the reference pressure. As an example, 90% to 110% of the reference pressure may be set as a normal range. Since the pressure value sensed by the pressure sensor 143 may temporarily fluctuate, it is preferable to determine by setting a normal range.

Determining whether the urea water is normally discharged from the urea water pump 123 is to apply a certain drive signal to the urea water pump 123 as in the step ⓒ, and the pressure value when air and urea water are discharged together is the above-mentioned It can be judged by whether it exceeds the normal range. In other words, when the pressure value sensed in real time does not exceed the normal range, i) within the normal range and ii) below the normal range, the 'first error' in which the urea water pump 123 cannot normally discharge the urea water defined as 'status'.

If it is confirmed as the first error state, it is set to repeatedly check whether urea water is introduced into and discharged from the urea water pump 123 by retrying the process ⓐ. However, if urea water is not drawn into the urea water pump 123 and only air is driven, there is a possibility of damage to the urea water pump 123 due to high heat. For protection of the urea water pump 123, it is preferable that repeated confirmation is limited to 2 to 5 times.

As described above, the number of elements Suction section may be composed of ⓐ to ⓒ processes. The above processes are separated by controlling the output of the urea water pump 123 and the air regulator 141. 4, in process ⓐ, the urea water pump 123 is operated with an output of 20 Hz, and in process ⓑ, the urea water pump 123 is operated with an output of 1 Hz, but the air regulator 141 can be driven together. In the ⓒ process of determining the state of the urea water pump 123, the state of the urea water pump 123 is determined by increasing the urea water pump 123 to an output of 10 Hz and checking whether the sensed pressure value is 300 mbar or more compared to the reference pressure do.

The 'second mode' is a mode for determining clogging of the urea water passage 120 including the urea water nozzle 142 . Referring to FIG. 6, in order to check the state of the urea water nozzle 142, the air valve 144 was turned ON/OFF for 1,000 seconds to measure the pressure, and the reference pressure indicated by the arrow should be measured, but in the graph of FIG. As shown, an accurate determination cannot be made because the measurement value varies greatly.

The cause is understood to be that when air is introduced into the urea water flow path 120 by the urea water pump 123, moisture in the urea water evaporates and fine urea crystals are generated.

The urea crystal attached to the inner wall of the urea water passage 120 flows into the urea water nozzle 142 while air is discharged, and the pressure value changes intermittently or irregularly.

Since the urea crystal has a property of being easily soluble in water, when the urea water is sprayed from the urea water pump 123 to the urea water passage 120, the urea water crystal melts in the urea water and the pressure value can be maintained constant. Based on this phenomenon, if the urea water and air are injected into the urea water passage 120 and the urea water nozzle 142, it is possible to maintain a constant pressure without urea crystal. ) and clogging of the urea water nozzle 142, as well as the overall condition can be checked.

The second mode may be understood as a mode in which urea water is injected through the urea water injection device 130 . This is also called 'SCR control'.

In the second mode, the maximum pressure is calculated based on the pressure value for the maximum injection amount of the urea water injected from the urea water injection device 130, and the blockage of the urea water passage 120 is determined using the maximum pressure . In addition, even when the reference pressure determined in the above-described first mode continues to increase, it is determined that the urea water passage 120 is defective. The defect of the element receiving passage 120 may be defined as a 'second error state'.

This will be described with reference to FIG. 7 . In the second mode, the minimum amount of urea water is injected, and the pressure value is sensed while being injected together with air. Based on the reference pressure set in the first mode, a normal range ('permissible pressure' in FIG. 7) is set.

Like the yellow line, if it comes between the reference pressure and the allowable pressure, it is determined as a 'normal state', and if it is more than the allowable pressure, like the orange line, it is determined as clogging of the urea water nozzle 142. As shown in the red line, when the allowable pressure is greatly out of range, it is determined that there is an overall problem with the urea water passage 120 and the urea water nozzle 142.

In the second mode, as an example, i) when the normal range determined in the first mode is exceeded, ii) when the maximum pressure is calculated in plurality, but the slope values of the Nth maximum pressure and the N+1th maximum pressure increase It can be set to determine that the urea water passage 120 is clogged.

The above-described first and second modes may be automatically controlled through the control module 150, and may be configured to provide monitoring results to an administrator terminal in real time.

8 is a graph showing another example of an abnormal state of a urea water nozzle or a urea water passage. Referring to FIG. 8 , when the pressure value increases due to the clogging of the urea water nozzle 142, a problem in which the deviation of the pressure value decreases occurs. Referring to the graph at the bottom, it can be seen that the pressure value greatly increases even if the urea water pump 123 is not driven and only the air regulator 141 is operated. That is, it means that there is no difference in the pressure value between the case where only air is supplied and the case where air and urea water are supplied together. In this case, it is difficult to determine the normal operation of the urea water pump 123 in the first mode described above.

Meanwhile, the present invention may operate the third mode. The third mode may be understood as a mode of cleaning the urea water passage 120 . The inside of the urea water passage 120 may be cleaned by flowing only a minimum amount of urea water without supplying air. Of course, when connected to a separate washing water tank (not shown) in addition to the urea water passage 120, the urea water passage 120 may be washed using specialized washing water instead of urea water.

Referring to FIG. 9, a method of controlling the urea water injection system according to the present invention will be described. A description overlapping with the foregoing will be omitted.

The present invention includes steps S110 to S150.

In step S110, the urea water pump 123 is operated with the first output for a preset time while the air valve 144 is closed, so that the urea water in the urea water tank 110 is converted to the first urea water flow. It is a step that cycles along (121).

Step (S120) is a step in which the air valve 144 is opened, air is supplied from the air regulator 141, and the urea water pump 123 is operated with a second output smaller than the first output, and the air flow path 140 The three-way valve 124 connected to the air branch passage 160 branched from the urea water passage 160 and the first and second urea water passages 121 and 122 is adjusted to communicate with the second urea water passage 122, so that the urea water tank This is a step in which the urea water and air of (110) are discharged through the urea water nozzle 142.

Step S130 is a step in which a pressure value of the fluid discharged from the urea water nozzle 142 is obtained using the pressure sensor 143, and a reference pressure is calculated using a method in which the pressure value is preset.

Step S140 is a step for determining the normal discharge state of the urea water pump 123 by comparing the reference pressure calculated in step S130 with the pressure value of the fluid discharged from the urea water nozzle 142 . At this time, the control module 150 calculates the normal range using the reference pressure, but when the pressure value of the fluid exceeds the normal range, it may be determined that the urea water pump 123 is in a normal discharge state.

Step S150 is a step of operating in the second mode in which urea water is injected through the urea water spraying device 130 . In the second mode, the maximum pressure is calculated based on the pressure value for the maximum injection amount of the urea water injected from the urea water injection device 130, and the blockage of the urea water passage 120 is determined using the maximum pressure It is a step.

The above-described urea water injection system of the present invention may be implemented as a program (or application) to be executed in combination with a server, which is hardware, and stored in a medium.

The above-described program is C, C++, JAVA, machine language, etc. It may include a code coded in a computer language. These codes may include functional codes related to functions defining necessary functions for executing the methods, and include control codes related to execution procedures necessary for the processor of the computer to execute the functions according to a predetermined procedure. can do. In addition, these codes may further include memory reference related codes for which location (address address) of the computer's internal or external memory should be referenced for additional information or media required for the computer's processor to execute the functions. there is. In addition, when the processor of the computer needs to communicate with any other remote computer or server in order to execute the functions, the code uses the computer's communication module to determine how to communicate with any other remote computer or server. It may further include communication-related codes for whether to communicate, what kind of information or media to transmit/receive during communication, and the like.

The storage medium is not a medium that stores data for a short moment, such as a register, cache, or memory, but a medium that stores data semi-permanently and is readable by a device. Specifically, examples of the storage medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc., but are not limited thereto. That is, the program may be stored in various recording media on various servers accessible by the computer or various recording media on the user's computer. In addition, the medium may be distributed to computer systems connected through a network, and computer readable codes may be stored in a distributed manner.

Steps of a method or algorithm described in connection with an embodiment of the present invention may be implemented directly in hardware, implemented in a software module executed by hardware, or implemented by a combination thereof. A software module may include random access memory (RAM), read only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, hard disk, removable disk, CD-ROM, or It may reside in any form of computer readable recording medium well known in the art to which the present invention pertains.

In the above, the present specification has been described with reference to the embodiments shown in the drawings so that those skilled in the art can easily understand and reproduce the present invention, but this is only exemplary, and those skilled in the art can make various modifications and equivalents from the embodiments of the present invention. It will be appreciated that embodiments are possible. Therefore, the scope of protection of the present invention should be defined by the claims.

110: urea water tank
120: urea feeding passage
121: first urea feeding passage
122: second urea feeding passage
130: urea water injection device
140: air flow
150: control module
160: air branch passage

Claims (8)

As a urea water injection system for supplying urea water to a selective catalytic reduction (SCR) of an exhaust gas reduction device,
A urea water tank 110 in which urea water is stored;
As a urea water flow path 120 for supplying urea water from the urea water tank 110 using the urea water pump 123, the urea water in the urea water tank 110 is returned to the urea water tank 110. A urea water passage 120 including a first urea water passage 121 for circulation and a second urea water passage 122 for supplying urea water to the urea water injection device 130;
An air flow path 140 that supplies air to the urea water nozzle 142 connected to the urea water injection device 130 by using the air regulator 141, and is combined with the second urea water flow path 122 at one point. an air flow path 140 formed in a branch shape and equipped with a pressure sensor 143 for sensing the pressure of the fluid discharged from the urea water nozzle 142; and
As a control module 150 for operating the urea water pump 123 and the air regulator 141 in a preset manner, in a first mode in which the urea water pump 123 and the air regulator 141 are operated together, the pressure After calculating the reference pressure using the sensor 143, the control module 150 for acquiring the pressure value of the fluid discharged from the urea water nozzle 142 at a predetermined cycle;
including,
The air flow path 140,
An air valve 144 for controlling air supplied from the air regulator 141 is provided, and at the rear end of the air valve 144, the first urea water passage 121 and a 3-way valve ( 124) further includes an air branch passage 160 connected through,
The control module 150,
Using the calculated reference pressure, the normal range is calculated,
When the pressure value of the fluid exceeds the normal range, it is determined that the urea water pump 123 is in a normal discharge state,
Urea water injection system.
According to claim 1,
The three-way valve 124,
The first side is connected to the second element water passage 122, the second side is connected to the first element water passage 121, and the third side is connected to the air branch passage 160.
Urea water injection system.
According to claim 2,
The first mode,
After the urea water pump 123 is operated with the first output for a preset time in a state in which the air valve 144 is closed,
The urea water pump 123 is operated with a second output lower than the first output, the air valve 144 is opened and air is supplied from the air regulator 141, and the three-way valve 124 In the state of communication with the first side, the pressure maintained for a preset time is determined as the reference pressure,
Urea water injection system.
According to claim 3,
The control module 150,
In the first mode, when the pressure value of the fluid is less than the normal range, the first mode is set to be repeatedly performed by a preset number of times,
Urea water injection system.
According to claim 1,
The control module 150,
It operates in a second mode in which urea water is injected through the urea water injection device 130,
In the second mode,
Calculate the maximum pressure based on the pressure value for the maximum injection amount of the urea water injected from the urea water injection device 130, and determine the blockage of the urea water passage 120 using the maximum pressure,
Urea water injection system.
According to claim 5,
In the second mode,
When exceeding the normal range determined in the first mode; or
When the maximum pressure is calculated in plurality, but the slope values of the Nth maximum pressure and the N+1th maximum pressure increase; Determined by the clogging of the urea water passage 120,
Urea water injection system.
A method for controlling the urea water injection system according to any one of claims 1 to 6,
(a) With the air valve 144 closed, the urea water pump 123 is operated with the first output for a preset time, so that the urea water in the urea water tank 110 flows into the first urea water flow path ( 121), step S110;
(b) the air valve 144 is opened, air is supplied from the air regulator 141, and the urea water pump 123 is operated with a second output smaller than the first output, wherein the air flow path The air branch passage 160 branching from the air passage 140 and the three-way valve 124 connected to the first and second element water passages 121 and 122 are controlled to communicate with the second element water passage 122, , The urea water and air in the urea water tank 110 are discharged to the urea water nozzle 142, step (S120);
(c) obtaining a pressure value of the fluid discharged from the urea water nozzle 142 using the pressure sensor 143, and calculating a reference pressure using the pressure value in a preset method ( S130); and
(d) comparing the reference pressure calculated in step (c) with the pressure value of the fluid discharged from the urea water nozzle 142 to determine the normal discharge state of the urea water pump 123 (S140) ; Including,
In step (d),
The control module 150,
Calculate the normal range using the reference pressure,
When the pressure value of the fluid exceeds the normal range, it is determined that the urea water pump 123 is in a normal discharge state,
method.
According to claim 7,
After step (d),
(e) operating in a second mode in which urea water is injected through the urea water injector 130, in the second mode, for the maximum injection amount of the urea water injected from the urea water injector 130 Calculating a maximum pressure based on the pressure value, and determining whether the urea water passage 120 is clogged using the maximum pressure (S150); Including more,
method.

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