KR101965853B1 - Urea water solution supply apparatus for exhaust gas purification - Google Patents

Abstract

An embodiment of the present invention relates to a urea supply system, comprising: a tank module storing an aqueous urea solution; a spray module spraying the aqueous urea solution into an exhaust pipe of an internal combustion engine; and an aqueous urea solution feed pipe connecting the tank module and the spray module. Disclosed is the urea supply system, comprising: a transmission pipe of which one end is connected to the feed pipe, and of which the other end is situated below a water level of the aqueous urea solution in the tank module; a retrieval pipe branched from the transmission pipe and having an opened end part opened in the tank module; a first valve opening and closing the retrieval pipe; a first air introduction pipe of which one end is connected to the feed pipe, and of which the other end is opened in the air; and a second valve opening and closing the first air introduction pipe.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a Urea water-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a technique for reducing nitrogen oxides (NOx), which is a harmful exhaust gas discharged from an internal combustion engine or a combustor, and more particularly to a technique for preventing freezing damage in winter by using an urea aqueous solution as a reducing agent The present invention relates to an urea aqueous solution supply system for exhaust purification which effectively recovers or purges an aqueous urea solution present in a urea aqueous solution transfer pipe at the time of shutdown.

As environmental regulations have become more stringent, attention has been focused on the reduction of NOx emissions from diesel engines. Recently, exhaust gas regulations for diesel engine vehicles have been tightened, and exhaust gas regulations applied only to vehicles have been extended to ships, construction machinery, and agricultural machinery.

As a post-treatment technique for reducing NOx in diesel engine exhaust gas, SCR (Selective Reduction Catalyst) technology, which reduces NOx by injecting urea aqueous solution as a reducing agent into an exhaust pipe, is representative.

Such SCR technology requires ammonia as a reducing agent for the selective reduction of nitrogen oxides in the exhaust pipe. In a currently used technique, an aqueous urea solution is injected into an exhaust gas, and ammonia produced by pyrolysis in the exhaust gas is used as a reducing agent.

On the other hand, even if the urea aqueous solution remains in the pipe and the parts of the urea supply system after the vehicle has stopped operating, solid ammonium may be formed and the channel may become blocked, and the urea aqueous solution may freeze The urea aqueous solution present in the urea aqueous solution conveying pipe should be recovered after the vehicle is turned off to prevent the film strength of the cooling part of the urea aqueous solution supply system and the freezing damage in winter.

For this purpose, there is a method of purging the supply system of urea aqueous solution by supplying compressed air, or a method of recovering urea by reversing the diaphragm pump. However, since an air compressor or an expensive pump must be provided, This is inconvenient.

Patent Document 1: WO2006-051017 (published on May 18, 2006) Patent Document 2: WO2004-047963 (published on June 10, 2004)

It is an object of the present invention to provide an effective method for recovering a urea aqueous solution existing in a pipeline of a urea supply system and each component after a vehicle has stopped operating .

Also, according to an embodiment of the present invention, there is disclosed a urea supply system and a urea supply method capable of reducing the time and space required for improving the atomization characteristics of an aqueous urea solution injected into an exhaust pipe and pyrolyzing the same into ammonia.

According to another embodiment of the present invention, there is disclosed a urea supply system and a method for preventing urea aqueous solution from being heated to form solid ammonium when temperature rises in a nozzle portion due to exhaust heat.

According to an embodiment of the present invention, there is provided a urea supply system comprising a tank module for storing an aqueous urea solution, a spray module for injecting an aqueous urea solution into an exhaust pipe of the internal combustion engine, and a urea aqueous solution delivery pipe for connecting the tank module and the spray module A delivery pipe having one end connected to the transfer pipe and the other end positioned below the level of the urea aqueous solution in the tank module; A return pipe branching from the delivery pipe and having an end open in the tank module; A first valve for opening / closing the return pipe; A first air inlet pipe having one end connected to the transfer pipe and the other end opened to the air; And a second valve for opening and closing the first air inlet pipe.

According to an embodiment of the present invention, there is provided a urea supply system comprising a tank module for storing an aqueous urea solution, a spray module for injecting an aqueous urea solution into an exhaust pipe of the internal combustion engine, and a urea aqueous solution delivery pipe for connecting the tank module and the spray module A delivery pipe having one end connected to the transfer pipe and the other end positioned below the level of the urea aqueous solution in the tank module; A return pipe branching from the delivery pipe and having an end open in the tank module; A first valve for opening / closing the return pipe; An air inlet pipe having one end connected to the transfer pipe and the other end opened to the air; And a second valve for opening and closing the air inlet pipe, wherein the tank module includes a low pressure pump for transferring the urea aqueous solution stored in the tank module to the injection module, And a high-pressure pump for discharging the urea aqueous solution transferred to the high-pressure pump to a high pressure.

The urea aqueous solution supply system according to an embodiment of the present invention simultaneously opens the both valves of the urea transfer pipe connecting the urea tank and the injection nozzle at the time of stopping the operation and operates the pump for a predetermined time to operate the urea transfer pipe and the urea remaining in the pump module There is an advantage that the aqueous solution can be recovered or purged.

According to another embodiment of the present invention, in a urea supply system composed of a tank module and an injection module, a low-pressure pump is installed in a tank module and a high-pressure pump is installed in the injection module, thereby improving the atomization characteristics of the urea aqueous solution injected into the exhaust pipe of the internal combustion engine. Thereby reducing the time and space required for pyrolysis with ammonia.

1 is a view for explaining an exemplary configuration in which a urea supply system according to the first embodiment is installed in an internal combustion engine,
2 is a view for explaining a tank module and a transfer pipe connected thereto according to an embodiment,
3 is a view for explaining an injection module according to the first embodiment and a transfer pipe connected thereto;
4 is a view for explaining another embodiment of the conveyance pipe,
5 is a view for explaining the injection module according to the second embodiment,
6 is a view for explaining the injection module according to the third embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description of preferred embodiments with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In the drawings, numerical values such as length, thickness, width, etc. of the components can be exaggerated for an effective explanation of technical contents.

In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms "comprise" and / or "comprising" used in the specification do not exclude the presence or addition of one or more other elements.

Hereinafter, the present invention will be described in detail with reference to the drawings. In describing the specific embodiments below, various specific contents have been set forth in order to explain the invention in more detail and to aid understanding. However, it will be appreciated by those skilled in the art that the present invention may be understood by those skilled in the art without departing from such specific details. In some cases, it should be mentioned in advance that it is common knowledge in describing an invention, and that parts not significantly related to the invention are not described in order to avoid confusion in describing the invention.

1 is a view for explaining an exemplary configuration in which a urea supply system according to the first embodiment is installed in an internal combustion engine.

Referring to the drawings, a urea supply system according to an embodiment of the present invention includes a tank module 200 for storing urea aqueous solution, a jetting module 300 for jetting urea aqueous solution, and a jetting module 300 for connecting the tank module 200 and the jetting module 300 (Or selective reduction catalyst 120), which may be composed of a transfer pipe 400, which is connected to the exhaust pipe 110, which is a passage of exhaust gas after being combusted in the internal combustion engine (or combustor) As shown in Fig.

The urea aqueous solution stored in the tank module 200 is supplied to the injection module 300 via the transfer pipe 400 and the supplied urea aqueous solution is supplied to the injection nozzle 300 of the injection module 300. [ To the exhaust pipe 110 through the exhaust pipe 110. The sprayed urea aqueous solution is hydrolyzed by the heat of the exhaust gas to be supplied to the SCR 120. The SCR 120 adsorbs the supplied ammonia and removes the denitrification reaction between the adsorbed ammonia and the nitrogen oxides (NOx) Thereby purifying the nitrogen oxides and converting them into harmless nitrogen gas (N2).

When the operation of the internal combustion engine 100 is stopped, the urea aqueous solution remaining in the injection module 300 is injected into the exhaust pipe 110 by the injection nozzle, and the urea aqueous solution filling the transfer pipe 400 passes through the transfer pipe 400 And is collected in the tank module 200 to perform the purging operation.

In an embodiment of the present invention, the end of the tank module 200 at either end of the transfer pipe 400 is opened in the space inside the tank module 200 and the end of the injection module 300 is opened in the atmosphere. Accordingly, since both ends of the closed transfer pipe 400 are exposed to the atmospheric pressure, the urea aqueous solution filling the inside of the transfer pipe 400 flows from a high position to a low position. According to the embodiment of the present invention, as shown in the drawing, the urea supply system is arranged such that the height H1 of the end of the transfer tube 400 on the side of the tank module 200 is higher than the height H2 of the end of the injection module 300 side The urea aqueous solution filling the inside of the transfer pipe 400 can be recovered to the tank module 200 along the transfer pipe 400.

2 is a view for explaining a tank module and a transfer pipe connected thereto according to an embodiment.

The tank module 200 includes a tank module main body 210 storing a urea aqueous solution, a delivery pipe 220 delivering the urea aqueous solution, a recovery pipe 230 branched from the delivery pipe 220, (240) for opening and closing the valve (230).

The tank module main body 210 is a storage container for storing an aqueous urea solution, and an urea aqueous solution inlet 211 is formed at an upper end thereof. The urea aqueous solution injected into the tank module body 210 through the injection port 211 can be filled up to the lower end of the injection port 211 at the maximum level indicated by "L".

The delivery pipe 220 is a pipe that penetrates the tank module body 210 in the vertical direction and has an upper end connected to the transfer pipe 400 and a lower end 222 positioned below the level of the urea aqueous solution in the tank module. In the illustrated embodiment, the lower end 222 extends down to a height adjacent the bottom surface of the tank module body 210.

The urea aqueous solution stored in the tank module 200 can be supplied to the lower end of the delivery pipe 220 when the pump disposed in the injection module 300 is operated to inject the urea aqueous solution into the exhaust pipe 110 through the injection module 300. [ May be sucked into the discharge pipe 220 through the discharge pipe 222 and supplied to the injection module 300 through the transfer pipe 400.

In one embodiment, the return pipe 230 is branched from the urea delivery pipe 220. One end of the recovery pipe 230 is connected to the discharge pipe 220 and the other end 231 is opened to the air. In the illustrated embodiment, the other end 231 of the recovery pipe 230 is opened toward the air at a height higher than the maximum level L of the space filled with air inside the body 210 of the tank module, that is, the urea aqueous solution . In one embodiment, this space within the body 210 of the tank module may be hermetically sealed from the outside of the body 210, and in an alternative embodiment, for example, a through- So that the space inside the main body 210 and the outside of the main body 210 can communicate with each other.

On the path of the recovery pipe 230, an opening / closing valve 240 for opening / closing the recovery pipe 230 may be installed. In one embodiment, the on-off valve 240 may be implemented as a conventional solenoid valve, and in alternative embodiments may use a three-way valve.

When the internal combustion engine 100 is operating, the return pipe 230 is closed by the opening / closing valve 240, and thus the urea aqueous solution is supplied to the injection module 300 through the discharge pipe 220 and the transfer pipe 400 .

When the operation of the internal combustion engine 100 is stopped, the open / close valve 240 opens the recovery pipe 230 for purging the transfer pipe 400, and the urea aqueous solution filling the transfer pipe 400 is returned to the recovery pipe 230 To the inside of the main body 210 of the tank module. Some of the recovered urea aqueous solution may be recovered through the discharge pipe 220 but may be recovered because the lower end 222 of the discharge pipe 220 is positioned below the level of the urea aqueous solution in the tank module 200 Most of the urea aqueous solution is recovered through the recovery pipe 230.

Although not shown, the tank module 200 may further include a control unit for controlling the operation of the opening / closing valve 240, a level sensor for measuring the level of the urea aqueous solution in the tank module, a concentration sensor for measuring the concentration of the urea aqueous solution, have.

3 is a view for explaining an injection module according to the first embodiment and a transfer pipe connected thereto.

Referring to the drawings, the injection module 300 according to one embodiment may include an inlet port 310, a pump 340, an injection quantity control valve 350, and an injection nozzle 360. The inlet port 310 is connected to the transfer pipe 400 and is a port through which the urea aqueous solution transferred from the tank module 200 flows into the injection module 300.

The pump 340 is a device for transferring urea aqueous solution from the tank module 200 to the injection module 300, and may be implemented as a gear pump in one embodiment. The gear housing 342, the driving gear 343, and the subsidiary gear 344 as shown in the figure. Since the high-pressure pump having such a structure is a technique known in the art, detailed description is omitted. The pump 340 may also be implemented as a pump other than a gear pump.

The urea aqueous solution transferred to the injection module 300 through the inlet port 310 enters the pump 340 through the inlet 345 of the pump 340 and then flows through the outlet 346 of the high pressure pump 340, (360). A spray amount control valve 350 may be installed in the path between the discharge port 346 of the pump 340 and the spray nozzle 360. The injection amount control valve 350 is a valve for controlling the injection amount of the urea aqueous solution injected through the injection nozzle 360, and may be implemented as a solenoid valve, for example. In the illustrated embodiment, the injection module 300 may further include a pressure control valve 370 to maintain the pressure of the urea aqueous solution applied to the injection amount control valve 350 constant. The injection quantity control valve and the pressure control valve are well known in the art, and thus detailed description thereof will be omitted.

In one embodiment, the pump 340, the injection amount regulating valve 350, and the pressure regulating valve 370 may be controlled by a control unit (not shown). Although not shown, a control line for transmitting control signals to the pump 340, the injection amount control valve 350, and the pressure control valve 370 of the injection module 300 is connected to the control unit, Can control each pump and valves.

Meanwhile, in the illustrated embodiment, the transfer pipe 400 includes an air inlet pipe 410 and an opening / closing valve 411 at a position adjacent to the inlet port 310 of the injection module 300. One end of the air inflow pipe 410 may be connected to the transfer pipe 400 and the other end may be opened in the air. The on-off valve 411 may be implemented as a solenoid valve and, in an alternative embodiment, may be implemented as a three-way valve. When the three-way valve is implemented, the opening / closing valve 411 closes the air inlet pipe 410 so that the urea aqueous solution can be transferred to the transfer pipe 400 while the internal combustion engine is operated. When the internal combustion engine is stopped, Is configured to open the air inlet pipe 410 so as to flow backward along the transfer pipe 400 and to be recovered to the tank module 200 and to close the path of the transfer pipe 400 in the direction toward the injection module 300 .

In one embodiment, the air inlet pipe 410 is preferably installed at a physically higher position than the installed height of the return pipe 230 of the tank module 200. A portion of the air inlet pipe 410 to which the air inlet pipe 410 is connected to the transfer pipe 400 is installed at a position higher than the open end 231 of the return pipe 230 do. Preferably, the height of the air inlet pipe 410 is gradually increased from any open end 231 of the return pipe 230 to any one end of the air inlet pipe 410 at any arbitrary point in the transfer pipe 400. With this configuration, when the opening / closing valve 240 of the tank module 200 and the opening / closing valve 411 of the air inlet pipe 410 are opened, the urea aqueous solution in the transfer pipe 400 is transferred Can be flowed down through the pipe (400) and recovered to the tank module (200).

The operation of the urea supply system including the tank module 200, the injection module 300, and the transfer pipe 400 as described above will be described. First, when the internal combustion engine 100 is operated, the urea supply system supplies the urea aqueous solution to the exhaust pipe 110 via the opening / closing valve 240 of the tank module 200 and the opening / The pump 411 is closed and the pump 340 is operated. The urea aqueous solution stored in the tank module main body 210 is supplied to the injection module 300 along the transfer pipe 400 because the return pipe 230 and the air inflow pipe 410 are closed by the two valves 240 and 411. [ And is injected into the exhaust pipe 110 through the injection nozzle 360.

When the operation of the internal combustion engine 100 is stopped, the urea supply system according to the present invention includes an operation (hereinafter also referred to as "first purging mode") for purging the urea aqueous solution left in the transfer tube 400 of the urea aqueous solution, (Hereinafter also referred to as "second purging mode") for a predetermined period of time.

For the first purging mode, the two valves 240 and 411 are operated to open the return pipe 230 and the air inlet pipe 410. Accordingly, the urea aqueous solution remaining in the path between the two valves 240 and 411 in the transfer pipe 400 is recovered into the tank module body 210 through the recovery pipe 230.

For the second purging mode, the injection module 300 is operated in a state in which the open / close valve 411 on the side of the air inflow pipe 410 is opened. The return pipe 230 may be opened or closed. The external air is sucked into the injection module 300 through the air inflow pipe 410 according to the operation of the injection module 300 and the air is introduced into the injection module 300 by the operation of the on- The injection module 300 can be purged while being sprayed to the exhaust pipe 110 together with the urea aqueous solution remaining in the exhaust pipe 300.

In one embodiment, the first and second purging modes may proceed sequentially, and in an alternative embodiment, the first and second purging modes may be performed simultaneously.

4 shows another embodiment of the air inlet pipe and the valve installed in the transfer pipe.

In FIG. 4, the injection module 300 is the same as the injection module 300 of FIG. 3, and thus description thereof is omitted. 4, the transfer pipe 400 includes a first air inlet pipe 410, a first inlet pipe valve 411, a second air inlet pipe 420, and a second inlet pipe valve 421 do. The first air inlet pipe 410 is located at the end of the transfer pipe 400 adjacent to the inlet port 310 of the injection module 300. The first inlet pipe valve 411 is for opening and closing the first air inlet pipe 410 and may be installed at a connection portion between the transfer pipe 400 and the first air inlet pipe 410.

One end of the second air inflow pipe 420 is located between the first air inflow pipe 410 and the inflow port 310 of the injection module 300 and is connected to the transfer pipe 400, 420 are opened in the air. The second inlet pipe valve 421 is for opening and closing the second air inlet pipe 420 and may be installed at a connection portion between the transfer pipe 400 and the second air inlet pipe 420.

In the illustrated embodiment, the transfer tube 400 further includes a transfer tube valve 430. The transfer pipe valve 430 is a valve for opening and closing the transfer pipe 400. The transfer pipe valve 430 is a valve for connecting the first air inflow pipe 410 and the transfer pipe 400 and the second air inflow pipe 420 and the transfer pipe 400, As shown in Fig.

The first inlet pipe valve 411, the second inlet pipe valve 421, and the transfer pipe valve 430 may each be constituted by a solenoid valve. In an alternative embodiment, the first inlet pipe valve 411 and the transfer pipe valve 430 may be configured as one three-way valve, or the second inlet pipe valve 421 and the transfer pipe valve 430 may be one three- .

Also, although not shown in the drawing, the urea supply system according to one embodiment includes an open / close valve 240, a first inflow pipe valve 411, a second inflow pipe valve 421, a transfer pipe valve 430, And a control unit (not shown) for controlling the operation of each of the plurality of microcomputers 300.

The open / close valve 240 and the first inlet pipe valve 411 of the return pipe 230 are opened and the transfer pipe valve 430 is closed for the operation of the first purging mode. The urea aqueous solution remaining in the transfer pipe 400 between the first inlet pipe valve 411 and the opening and closing valve 240 is recovered to the tank module 200 through the recovery pipe 230.

In the second purging mode, the second inlet pipe valve 421 is opened and the transfer pipe valve 430 is closed. Thereafter, the injection module 300 is operated to inject the urea aqueous solution in the injection module 300 into the exhaust pipe 110, thereby purging the injection module 300.

In one embodiment, the first and second purging modes may proceed sequentially, and in an alternative embodiment, the first and second purging modes may be performed simultaneously.

5 shows the injection module 500 according to the second embodiment. In the drawing, the tank module 200 and the transfer pipe 400 are the same as or similar to the tank module 200 and the transfer pipe 400 shown in FIGS. 5, the tank module 200 further includes a low-pressure pump 250 for transferring urea aqueous solution stored in the tank module 200 to the injection module 500.

In one embodiment, the low-pressure pump 250 may be installed at any position of the delivery pipe 220. In the illustrated embodiment, the low-pressure pump 250 may be installed by coupling the delivery pipe 220 and the delivery pipe 400. The inlet of the low pressure pump 250 is coupled to the upper end of the delivery pipe 220 and the outlet of the low pressure pump 250 is coupled to the delivery pipe 400 and the end.

The low pressure pump 250 transfers the urea aqueous solution stored in the tank module 200 to the injection module 500 at a low pressure. Here, 'low pressure' may be, for example, 5 bar. Preferably, in one embodiment, the 'low pressure' can be a pressure between 2 bar and 10 bar, more preferably between 2 bar and 6 bar.

Referring to the drawings, the injection module 500 according to the second embodiment includes a cooling channel 530, a pump 540, an injection amount control valve 550, a pressure control valve 570, and a spray nozzle 560 can do. The injection amount control valve 550, the pressure control valve 570 and the injection nozzle 560 are the same as the injection amount control valve 350, the pressure control valve 370, and the injection nozzle 360 described with reference to FIG. And description thereof will be omitted.

5, the pump 540 of the injection module 500 is a high-pressure pump for discharging the urea aqueous solution through the injection nozzle 560 at a high pressure. Here, 'high pressure' may be, for example, 50 bar. Although it is not desirable to limit the maximum value of the 'high pressure' because the higher the pressure of the high pressure pump is, the higher the pressure of the high pressure pump is, in one embodiment, the pressure between 20 bar and 100 bar , Preferably between 40 bar and 60 bar.

The cooling channel 530 is a space formed within the injection module 500 and a space having a constant volume capable of accommodating the urea aqueous solution for cooling the injection module 500. The cooling channel 530 is configured to surround the injection nozzle 560 and is configured to cool the connection passage between the injection nozzle 560 and the injection nozzle 560 and the high pressure pump 540.

The cooling channel 530 includes an inlet passage 510 for receiving the urea aqueous solution from the transfer pipe 400 and a discharge passage 545 for discharging the aqueous urea solution to the high pressure pump 540. The urea aqueous solution flowing into the injection module 500 through the inflow passage 510 cools the injection module 500 while flowing through the cooling channel 530 and then is supplied to the high pressure pump 540 through the discharge passage 545, And is injected through the nozzle 560.

According to the embodiment of the present invention, when supplying the urea aqueous solution from the tank module 200 to the injection module 500, the low pressure pump 250 installed on the tank module 200 is used and the exhaust pipe The high pressure pump 540 installed in the injection module 500 is used in addition to the low pressure pump 250. Therefore, since the urea aqueous solution of a sufficiently high pressure can be injected into the exhaust pipe 110 through the injection nozzle 560, it can be atomized and pyrolyzed in a short time in the exhaust pipe 110 to generate ammonia. Thereby improving the atomization characteristics of the urea aqueous solution and reducing the time and space required for pyrolysis with ammonia.

FIG. 6 shows an injection module 600 according to a third embodiment.

The tank module 200 and the transfer tube 400 are the same as or similar to the tank module 200 and the transfer tube 400 shown in FIG. The injection module 600 according to the third embodiment may include a cooling channel 630, a pump 640, an injection amount regulating valve 650, a pressure regulating valve 670, and a spray nozzle 660, The components have the same or similar configurations and functions as those described with reference to Fig.

The injection module 600 of the third embodiment of FIG. 6 differs from the injection module 500 of the second embodiment (FIG. 5) in that the high-pressure pump 640 is disposed separately from the injection module body. At this time, the " injection module body " is a member directly attached to the exhaust pipe 110, for example, a member including the cooling channel 630 and the injection nozzle 460, the injection amount control valve 650 and the pressure control valve 670 to be.

The high pressure pump 640 in the injection module 600 of the third embodiment is disposed at a predetermined distance from the injection module main body and has an inlet 645 for receiving the urea aqueous solution from the cooling channel 630 and a high pressure pump 640 And an outlet 646 for discharging the high-pressure urea aqueous solution to the injection nozzle 660 side.

According to the injection module 600 of the third embodiment, since the high-pressure pump 640 does not directly contact the exhaust pipe 110, the need to cool the high-pressure pump 640 is reduced, and the urea aqueous solution of the cooling channel 630 It is possible to cool only the injection nozzle 660 and surrounding components without cooling the high-pressure pump 640, so that the cooling efficiency can be increased. However, since the injection pressure of the injection nozzle 660 decreases as the high-pressure pump 640 moves away from the injection nozzle 660, the cooling effect of the injection nozzle and the injection pressure are in a trade-off relationship. It is desirable to set the separation distance of the high-pressure pump 640.

It will be apparent to those skilled in the art that various modifications and variations may be made to the present invention without departing from the spirit or scope of the invention. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be determined by the scope of the appended claims, as well as the appended claims.

100: Internal combustion engine
110: Exhaust pipe
120: SCR
200: tank module
300, 500, 600: injection module
400: Transfer pipe

Claims (17)

A urea supply system (200) including a tank module (200) for storing a urea aqueous solution, an injection module (300) for injecting a urea aqueous solution into an exhaust pipe of an internal combustion engine, and a urea aqueous solution transfer pipe As a result,
A discharge pipe (220) having one end connected to the transfer pipe (400) and the other end positioned below the level of the urea aqueous solution in the tank module;
A return pipe (230) having an end (231) that branches off from the delivery pipe (220) and opens in the tank module;
A first valve (240) for opening / closing the return pipe (230);
A first air inflow pipe 410 having one end connected to the transfer pipe 400 and the other end opened to the air;
A second valve (411) for opening / closing the first air inlet pipe;
A second air inlet pipe 420 having one end positioned between one end of the first air inlet pipe 410 and the injection module and connected to the transfer pipe 400 and the other end opened to the air;
A third valve (421) for opening / closing the second air inlet pipe (420); And
And a fourth valve 430 located between one end of the first air inflow pipe 410 and one end of the second air inflow pipe 420 and opening and closing the transfer pipe 400. Urea supply system. The method according to claim 1,
Wherein the open end of the return pipe (230) is located at a position higher than the maximum water level (L) of the aqueous urea solution in the tank module. 3. The method of claim 2,
Wherein the height of the one end of the first air inlet pipe (410) is higher than the height of the open end (231) of the return pipe (230). The method of claim 3,
The height of each of the first and second air inflow pipes 410 and 410 is gradually increased from the open end 231 of the return pipe 230 to one end of the first air inflow pipe 410 at any arbitrary point in the transfer pipe, 2 < / RTI > valve is opened, the urea aqueous solution in the transfer tube is recovered to the tank module through the transfer tube. The method of claim 3,
Further comprising a control section for controlling the operation of each of the first valve, the second valve, and the injection module,
A first purge mode in which the control unit opens the first valve and the second valve to recover the urea aqueous solution in the transfer tube through the recovery pipe after the operation of the internal combustion engine is stopped, And to operate the injection module to purging the urea aqueous solution in the injection module. 6. The method of claim 5,
Wherein the control unit sequentially or simultaneously executes the first purging mode and the second purging mode. 2. The apparatus of claim 1,
An injection nozzle for injecting the urea aqueous solution into the exhaust pipe of the internal combustion engine;
A pump for discharging the urea aqueous solution transferred to the injection module to the injection nozzle side; And
A cooling channel having a space having a constant volume capable of accommodating the urea aqueous solution and having an inlet passage formed to surround the injection nozzle and supplied with a urea aqueous solution from the transfer pipe and a discharge passage discharging the aqueous urea solution with the pump; The urea supply system comprising: The method according to claim 1,
Wherein the second and fourth valves are constituted by one three-way valve or the third and fourth valves are constituted by one three-way valve. The method according to claim 1,
Further comprising a control unit for controlling the operation of each of the first to fourth valves and the injection module,
A first purge mode in which after the operation of the internal combustion engine is stopped, the control unit opens the first and second valves and closes the fourth valve to recover the urea aqueous solution in the transfer pipe through the recovery pipe, And to execute a second purging mode in which the valve is opened, the fourth valve is closed, and the injection module is operated to pour the urea aqueous solution in the injection module. 10. The method of claim 9,
Wherein the control unit simultaneously executes the first purging mode and the second purging mode. 1. A urea supply system comprising a tank module (200) for storing a urea aqueous solution, an injection module for injecting an aqueous urea solution into an exhaust pipe of an internal combustion engine, and a urea aqueous solution transfer pipe (400) for connecting the tank module and the injection module,
A discharge pipe (220) having one end connected to the transfer pipe (400) and the other end positioned below the level of the urea aqueous solution in the tank module;
A return pipe (230) having an end (231) that branches off from the delivery pipe (220) and opens in the tank module;
A first valve (240) for opening / closing the return pipe (230);
An air inlet pipe 410 having one end connected to the transfer pipe 400 and the other end opened to the air; And
And a second valve (411) for opening and closing the air inlet pipe,
The tank module includes a low pressure pump (250) for transferring urea aqueous solution stored in the tank module to the injection module,
Wherein the injection module includes a high-pressure pump for discharging the urea aqueous solution delivered to the injection module at a high pressure. 12. The method of claim 11,
Wherein the open end of the return pipe (230) is located at a position higher than the maximum water level (L) of the aqueous urea solution in the tank module. 13. The method of claim 12,
Wherein the height of the one end of the air inlet pipe (410) is higher than the height of the open end (231) of the return pipe (230). 14. The method of claim 13,
The height of the first valve and the second valve is gradually increased from any open end 231 of the return pipe 230 to one end of the air inflow pipe 410 at any arbitrary point in the transfer pipe, The urea aqueous solution in the transfer pipe is recovered to the tank module through the transfer pipe. 12. The method of claim 11,
The low pressure pump transfers the urea aqueous solution to the injection module at a pressure of 10 Bar or less,
Wherein the high-pressure pump discharges the urea aqueous solution at a pressure between 20 bar and 100 bar. 12. The apparatus according to claim 11,
An injection nozzle 560 for injecting the urea aqueous solution into the exhaust pipe of the internal combustion engine; And
An inlet passage formed to surround the injection nozzle and having a constant volume capable of accommodating the urea aqueous solution, an inlet passage through which the urea aqueous solution is supplied from the transfer pipe 400, and an outlet passage through which the urea aqueous solution is discharged by the high- Cooling channel (530). ≪ / RTI > 17. The method of claim 16,
Wherein the injection module is divided into an injection module main body and the high pressure pump,
Wherein the injection nozzle and the cooling channel are disposed in the injection module body, and the high-pressure pump is disposed at a predetermined distance from the injection module main body.

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