Urea nozzle, exhaust aftertreatment system and vehicle

Abstract

The utility model discloses a urea nozzle, an exhaust aftertreatment system and a vehicle, and belongs to the technical field of automobile exhaust aftertreatment, the urea nozzle comprises a main body part, and a liquid injection channel and a gas purging channel are formed in the main body part; the inlet end of the liquid injection channel is connected with the liquid storage assembly, and the outlet end of the liquid injection channel is connected with the catalytic reaction module; the inlet end of the gas purging channel is connected with a gas supply module, and the gas supply module is used for providing high-pressure gas; and the outlet end of the gas purging channel is communicated with the liquid injection channel, so that the high-pressure gas enters the liquid injection channel and purges the liquid injection channel. According to the urea nozzle, high-pressure blowing can be conducted on the liquid spraying channel after spraying is finished, residual urea solution in the liquid spraying channel is removed, the problem that the urea nozzle is crystallized and blocked is fundamentally solved, the maintenance cost can be reduced, and the user experience is improved.

Description

Technical Field

[0001] The present application relates to the technical field of automobile exhaust aftertreatment, and in particular to a urea nozzle, an exhaust aftertreatment system and a vehicle. Background Art

[0002] In recent years, global warming and the greenhouse effect have intensified. To address this, countries have imposed stricter limits on vehicle emissions. Faced with increasingly stringent diesel engine emissions regulations, especially with the gradual implementation of the China VI emission standards, NOx (nitrogen oxide) emission limits have been significantly reduced. Urea selective catalytic reduction (Urea-SCR) technology, due to its high efficiency, selectivity, economy, and sulfur tolerance, has become a key technology for upgrading emissions from domestic light-duty diesel engines. In existing technologies, a urea solution is injected into the SCR catalyst via a urea nozzle. Under the catalytic action of the catalyst, the urea reacts with nitrogen oxides to produce harmless nitrogen, thereby reducing nitrogen oxide emissions. Urea nozzles are installed above the catalyst, where the engine exhaust flows. If a vehicle frequently idles for extended periods or is shut down after operating at high exhaust temperatures, the residual liquid in the nozzle cavity, exposed to high temperatures (greater than 150°C), can form biuret, a hard, water-insoluble crystalline substance.

[0003] The crystallized biuret has high hardness and stable chemical properties and is not easy to decompose, which will clog the injection hole of the urea nozzle. When the vehicle needs to inject urea, the urea nozzle is blocked and cannot be injected. The common practices for dealing with urea nozzle crystallization blockage failures are: first, the user removes the urea nozzle and manually cleans the crystals in the nozzle hole. This solution delays the normal operation of the vehicle and may not be able to completely clean the crystals in the tiny nozzle hole. It cannot eradicate the fault and requires frequent parking for cleaning. Second, directly replace the urea nozzle with a new one. This solution delays the user's normal vehicle operation, generates parts costs and increases the user's cost of use. It cannot eradicate the fault and requires frequent replacement of the urea nozzle. Utility Model Content

[0004] The present application provides a urea nozzle, an exhaust after-treatment system and a vehicle, aiming to solve the problem in the prior art that the urea nozzle is easily crystallized and clogged, affecting the normal operation of the vehicle.

[0005] The present application provides a urea nozzle, comprising a main body, wherein a liquid injection channel and a gas purge channel are formed inside the main body; an inlet end of the liquid injection channel is connected to a liquid storage assembly, and an outlet end of the liquid injection channel is connected to a catalytic reaction module;

[0006] The inlet end of the gas purge channel is connected to a gas supply module, which is used to provide high-pressure gas; the outlet end of the gas purge channel is connected to the liquid injection channel, so that the high-pressure gas enters the liquid injection channel and purges the liquid injection channel.

[0007] Optionally, the axis of the gas purge channel is arranged at an angle to the axis of the liquid injection channel.

[0008] Optionally, the angle between the axis of the gas purge channel and the axis of the liquid injection channel is set to 15°~30°.

[0009] Optionally, the inlet end of the gas purge channel and the inlet end of the liquid injection channel are arranged on the same side of the main body.

[0010] Optionally, the inlet end of the gas purge channel and the outlet end of the liquid injection channel are arranged on the same side of the main body.

[0011] The advantages of the urea nozzle described in this application over the prior art are:

[0012] The urea nozzle includes a main body, wherein a liquid injection channel and a gas purge channel are formed inside the main body; the inlet end of the liquid injection channel is connected to the liquid storage assembly, and the outlet end of the liquid injection channel is connected to the catalytic reaction module; the inlet end of the gas purge channel is connected to the gas supply module, and the gas supply module is used to provide high-pressure gas; the outlet end of the gas purge channel is connected to the liquid injection channel so that the high-pressure gas enters the liquid injection channel and purges the liquid injection channel. The urea nozzle provided in the present application provides a gas purge channel connected to the liquid injection channel, and inputs high-pressure gas from the gas purge channel. After the injection is completed, the liquid injection channel can be purged with high pressure, thereby removing the residual urea solution in the liquid injection channel and avoiding the formation of biuret crystals due to excessive temperature. This solves the problem of urea nozzle blockage from the root, helps to reduce maintenance costs, ensure the normal operation of the vehicle, and improve user experience.

[0013] The present application also provides an exhaust gas after-treatment system, comprising a urea supply module, a catalytic reaction module and a muffler module, wherein the urea supply module comprises the urea nozzle as described above.

[0014] Optionally, the exhaust after-treatment system also includes a gas supply module; the gas supply module includes an air filter and a high-pressure pump, the output end of the air filter is connected to the input end of the high-pressure pump, and the output end of the high-pressure pump is connected to the inlet end of the gas purge channel.

[0015] Optionally, a control valve is provided between the output end of the air filter and the input end of the high-pressure pump.

[0016] Optionally, the exhaust aftertreatment system further includes a control unit; the control unit is connected to the urea nozzle, the control valve, and the high-pressure pump, respectively, and is configured to control the opening of the control valve and the start-up of the high-pressure pump according to the completion of injection of the urea nozzle.

[0017] The advantages of the exhaust after-treatment system over the prior art are:

[0018] 1. The exhaust aftertreatment system, equipped with the aforementioned urea nozzle, can avoid the problem of urea nozzle clogging, ensuring that the urea supply module can normally and stably supply urea solution to the catalytic reaction module, thereby ensuring the stable progress of the catalytic reduction reaction and ultimately meeting the requirements for nitrogen oxide pollution gas emissions.

[0019] 2. The exhaust after-treatment system further includes a gas supply module, which includes an air filter and a high-pressure pump. The exhaust after-treatment system provided in this application rationally utilizes the air filter of the vehicle engine system to provide a clean purge gas source for the urea nozzle, thereby reducing the introduction of external equipment, improving the integration of the entire vehicle, and reducing the cost of gas supply.

[0020] The present application also provides a vehicle, comprising the urea nozzle or the exhaust after-treatment system as described above.

[0021] The advantages of the vehicle, the exhaust after-treatment system, and the urea nozzle described above over the prior art are the same and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 This is a structural diagram of a urea nozzle proposed in one embodiment of the present application;

[0024] Figure 2 Schematic diagram of the exhaust gas after-treatment system according to an embodiment of the present application.

[0025] Description of reference numerals:

[0026] 1. Urea supply module; 11. Liquid storage assembly; 12. Urea nozzle; 121. Liquid injection channel; 121a. Inlet end of liquid injection channel; 121b. Outlet end of liquid injection channel; 122. Gas purge channel; 122a. Inlet end of gas purge channel; 122b. Outlet end of gas purge channel; 2. Gas supply module; 21. Air filter; 22. High-pressure pump; 23. Control valve; 3. Catalytic reaction module; 31. Oxidation catalyst; 32. NOx selective catalytic reduction purifier; 33. Particulate filter; 4. Muffler module; 5. Control unit; 6. Turbocharger; 61. Impeller end; 62. Turbine end; 7. Intercooler heat dissipation module; 8. Engine. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] In related technologies, a urea solution is injected into the SCR catalyst through a urea nozzle. Under the catalytic action of the catalyst, the urea reacts with nitrogen oxides to produce harmless nitrogen, thereby reducing nitrogen oxide emissions. The urea nozzle is installed above the catalyst where the engine exhaust flows. If the vehicle frequently idles for extended periods or is shut down after operating at high exhaust temperatures, the residual liquid in the urea nozzle cavity, exposed to high temperatures (greater than 150°C), can form biuret, a hard, water-insoluble crystal.

[0029] The crystallized biuret has high hardness and stable chemical properties and is not easy to decompose. It will clog the injection hole of the urea nozzle. When the vehicle needs to inject urea, the urea nozzle is blocked and cannot be injected. The common practices for dealing with urea nozzle crystallization blockage failures are: first, the user removes the urea nozzle and manually cleans the crystals in the nozzle hole. This solution delays the normal operation of the vehicle and may not be able to completely clean the crystals in the tiny nozzle hole. It cannot eradicate the fault and requires frequent parking for cleaning. Second, directly replace the urea nozzle with a new one. This solution delays the user's normal vehicle operation, generates parts costs and increases the user's cost of use. It cannot eradicate the fault and requires frequent replacement of the urea nozzle.

[0030] In view of this, an embodiment of the present application provides a urea nozzle.

[0031] See also Figure 1A urea nozzle 12 includes a main body, wherein a liquid injection channel 121 and a gas purge channel 122 are formed inside the main body; the inlet end 121a of the liquid injection channel is connected to the liquid storage component 11, and the outlet end 121b of the liquid injection channel is connected to the catalytic reaction module 3; the inlet end 122a of the gas purge channel is connected to the gas supply module 2, and the gas supply module 2 is used to provide high-pressure gas; the outlet end 122b of the gas purge channel is in communication with the liquid injection channel 121, so that the high-pressure gas enters the liquid injection channel 121 and purges the liquid injection channel 121.

[0032] Specifically, the urea nozzle 12 includes a main body, within which a liquid injection channel 121 and a gas purge channel 122 are formed. The liquid injection channel 121 serves as a flow channel for the urea solution. Its inlet end 121a is connected to the liquid reservoir 11, which stores the urea solution required for the catalytic reduction reaction. Its outlet end 121b is connected to the catalytic reaction module 3, which includes an oxidation catalyst 31, a NOx selective catalytic reduction purifier 32, and a particulate filter 33. The outlet end 121b of the liquid injection channel is specifically connected to the NOx selective catalytic reduction purifier 32. When the urea nozzle 12 is in operation, the urea solution in the liquid reservoir 11 enters the urea nozzle 12 through the inlet end 121a of the liquid injection channel, flows through the liquid injection channel 121, and is then ejected from the outlet end 121b of the liquid injection channel into the NOx selective catalytic reduction purifier 32, participating in the catalytic reduction reaction.

[0033] The gas purge channel 122 is disposed adjacent to the liquid injection channel 121 and serves as a channel for introducing purge gas. The inlet end 122a of the gas purge channel is connected to the gas supply module 2, which is capable of supplying high-pressure gas to the gas purge channel 122. The outlet end 122b of the gas purge channel is connected to the liquid injection channel 121, enabling communication between the gas purge channel 122 and the liquid injection channel 121. After the urea nozzle 12 finishes spraying urea solution, high-pressure gas is introduced into the gas purge channel 122, allowing the high-pressure gas to flow along the gas purge channel 122 and into the liquid injection channel 121. The high-speed flow of the high-pressure gas allows the liquid injection channel 121 to be purged, thereby clearing any residual urea solution within the liquid injection channel 121 and preventing nozzle crystallization and blockage from occurring at the source.

[0034] Optionally, the axis of the gas purge channel 122 is arranged at an angle to the axis of the liquid injection channel 121 .

[0035] Specifically, the gas purge channel 122 can be a linear channel, a curved channel, or an irregularly shaped channel. In this embodiment, to reduce fluid flow resistance and facilitate the processing of the urea nozzle 12, the gas purge channel 122 is preferably configured as a linear channel. The liquid injection channel 121 is typically also configured as a linear channel, with the axis of the gas purge channel 122 and the axis of the liquid injection channel 121 being arranged at an angle.

[0036] Optionally, the angle between the axis of the gas purge channel 122 and the axis of the liquid injection channel 121 is set to 15° to 30°.

[0037] Specifically, the angle between the axis of the gas purge channel 122 and the axis of the liquid injection channel 121 is preferably set to an acute angle. This helps reduce the angular change in the flow direction of the high-pressure gas when it enters the liquid injection channel 121 from the gas purge channel 122, thereby helping to reduce airflow resistance, ensure a high gas flow rate, and improve the purge effect. As an example, the angle between the axis of the gas purge channel 122 and the axis of the liquid injection channel 121 can be set to 15° to 30°.

[0038] Optionally, the inlet end 122a of the gas purge channel and the inlet end 121a of the liquid injection channel are arranged on the same side of the main body.

[0039] For details, see Figure 1 In some embodiments, the inlet end 122a of the gas purge channel and the inlet end 121a of the liquid injection channel are located on the same side of the main body, and the outlet end 122b of the gas purge channel is located in the middle of the liquid injection channel 121. During high-pressure purging after urea solution injection, high-pressure gas enters the gas purge channel from the inlet end 122a, enters the liquid injection channel 121 through the outlet end 122b of the gas purge channel, and then flows at a high speed along the liquid injection channel 121 toward the outlet end 121b of the liquid injection channel to purge the liquid. Finally, the gas is discharged from the outlet end 121b of the liquid injection channel and enters the NOx selective catalytic reduction purifier 32. After the high-pressure gas purge, the urea solution remaining in the liquid injection channel 121 is blown out from the outlet end 121b of the liquid injection channel and enters the NOx selective catalytic reduction purifier 32.

[0040] Optionally, the inlet end 122a of the gas purge channel and the outlet end 121b of the liquid injection channel are arranged on the same side of the main body.

[0041] Specifically, in other embodiments, the inlet end 122a of the gas purge channel and the outlet end 121b of the liquid injection channel may be arranged on the same side of the main body, with the outlet end 122b of the gas purge channel being located in the middle of the liquid injection channel 121. When purging is performed after urea solution injection is completed, high-pressure gas enters from the inlet end 122a of the gas purge channel, enters the liquid injection channel 121 through the outlet end 122b of the gas purge channel, then flows at high speed along the liquid injection channel 121 toward the inlet end 121a of the liquid injection channel to achieve purging, and finally is discharged from the inlet end 121a of the liquid injection channel and enters the urea solution storage assembly 11. After purging by the high-pressure gas, the urea solution remaining in the liquid injection channel 121 is blown out from the inlet end 121a of the liquid injection channel and returned to the urea solution storage assembly 11.

[0042] In this embodiment, one gas purge channel 122 is provided and is located beside the liquid injection channel 121 . In other embodiments, more than one gas purge channel 122 may be provided and distributed around the liquid injection channel 121 .

[0043] The urea nozzle 12 provided in the embodiment of the present application has a gas purge channel 122 provided in the main body. After the urea injection is completed, high-pressure and high-speed gas is introduced to purge the liquid injection channel 121, thereby removing the urea solution remaining in the liquid injection channel 121, ensuring the cleanliness and unobstructed flow of the liquid injection channel 121. This can solve the problem of clogging of the urea nozzle 12 due to crystallization of residual urea solution at high temperature from the source, greatly reducing maintenance costs and helping to improve user experience.

[0044] The embodiment of the present application further provides an exhaust gas after-treatment system, including a urea supply module 1 , a catalytic reaction module 3 and a muffler module 4 . The urea supply module 1 includes the urea nozzle 12 as described above.

[0045] Specifically, the exhaust after-treatment system includes a urea supply module 1, a catalytic reaction module 3 and a muffler module 4. The urea supply module 1 is used to provide the urea solution required for the reaction to the catalytic reaction module 3. The catalytic reaction module 3 is mainly used to treat the pollutants and particulate matter in the exhaust gas. The muffler module 4 is used to reduce the noise generated by the vehicle exhaust.

[0046] The urea supply module 1 includes the urea nozzle 12 as described above, and also includes a liquid storage assembly 11. The liquid storage assembly 11 stores urea solution. The liquid outlet end of the liquid storage assembly 11 is connected to the inlet end 121a of the liquid injection channel of the urea nozzle 12. When the urea nozzle 12 is spraying, the liquid storage assembly 11 can supply urea solution to the liquid injection channel 121.

[0047] The catalytic reaction module 3 includes an oxidation catalyst 31, a NOx selective catalytic reduction purifier 32, and a particulate filter 33. The oxidation catalyst 31 mainly converts carbon monoxide and hydrocarbons in the exhaust gas into carbon dioxide and water vapor, and converts nitrogen monoxide in the exhaust gas into nitrogen dioxide, thereby increasing the nitrogen dioxide content in the exhaust gas and promoting the reduction reaction of nitrogen oxides. The NOx selective catalytic reduction purifier 32 reduces nitrogen oxides in the exhaust gas into harmless nitrogen and water. This process is achieved by injecting urea solution. The outlet end 121b of the liquid injection channel of the urea nozzle 12 is connected to the NOx selective catalytic reduction purifier 32, so that the urea nozzle 12 can inject urea solution into the NOx selective catalytic reduction purifier 32. The urea solution decomposes at high temperature to produce ammonia, which reacts with nitrogen oxides under the action of the catalyst, thereby reducing nitrogen oxide emissions. The particulate filter 33 can capture and store particulate matter in the exhaust gas, effectively reducing particulate matter emissions through physical filtration.

[0048] The exhaust after-treatment system of this embodiment, because it includes the urea nozzle 12, can remove residual urea solution in the liquid injection channel 121 by performing high-pressure purge on the liquid injection channel 121 of the urea nozzle 12 after injection. This can avoid the problem of clogging of the urea nozzle 12, ensure that the urea supply module 1 can normally and stably supply urea solution to the catalytic reaction module 3, and further ensure the stable progress of the catalytic reduction reaction, ultimately meeting the emission requirements of nitrogen oxide pollution gas.

[0049] Optionally, the exhaust after-treatment system also includes a gas supply module 2; the gas supply module 2 includes an air filter 21 and a high-pressure pump 22, the output end of the air filter 21 is connected to the input end of the high-pressure pump 22, and the output end of the high-pressure pump 22 is connected to the inlet end 122a of the gas purge channel.

[0050] For details, see Figure 2The exhaust aftertreatment system also includes a gas supply module 2, which includes an air filter 21 and a high-pressure pump 22. The air filter 21 is a built-in device of the vehicle engine system and is located at the compressor end 61 of the turbocharger 6. The compressor end 61 of the turbocharger 6 is connected to the intercooler module 7, and the turbine end 62 of the turbocharger 6 is connected to the engine 8. The air filter 21 is primarily used to remove harmful impurities from the air entering the cylinders of the engine 8. In this embodiment, a branch line is provided at the output end of the air filter 21. The air filtered by the air filter 21 is diverted through the branch line to the urea nozzle 12, thereby providing a source of clean purge gas for the urea nozzle 12. The high-pressure pump 22 is provided on a branch pipeline. The input end of the high-pressure pump 22 is connected to the output end of the air filter 21. The output end of the high-pressure pump 22 is connected to the inlet end 122a of the gas purge channel of the urea nozzle 12. The high-pressure pump 22 can pressurize the clean air output by the air filter 21 and then deliver it to the urea nozzle 12, so as to provide the urea nozzle 12 with high-pressure and high-flow-rate purge gas.

[0051] In this embodiment, an air filter 21 and a high-pressure pump 22 are used as the gas supply module 2. This rationally utilizes the vehicle's built-in air filter 21, reduces the need for external equipment, and significantly reduces the cost of air supply compared to using external high-pressure gas cylinders or compressed gas tanks. Furthermore, the air filter 21, as part of the vehicle's engine system, provides clean air to the engine's eight cylinders. It also serves as part of the vehicle's exhaust aftertreatment system, providing clean purge air to the urea nozzle 12. This achieves integration between the vehicle's engine system and the exhaust aftertreatment system, enhancing the vehicle's integrated level.

[0052] Optionally, a control valve 23 is provided between the output end of the air filter 21 and the input end of the high-pressure pump 22 .

[0053] Specifically, in order to facilitate the control of the on and off of the branch pipeline, a control valve 23 is also provided on the branch pipeline. The control valve 23 can be a solenoid valve. The control valve 23 is located between the output end of the air filter 21 and the input end of the high-pressure pump 22. When the control valve 23 is opened, the branch pipeline is in a flow state, and the gas output by the air filter 21 can flow into the high-pressure pump 22 for pressurization, so as to provide a gas source for subsequent purging work; when the control valve 23 is closed, the branch pipeline is in a cut-off state, and the gas output by the air filter 21 cannot flow into the high-pressure pump 22, the purging gas source is cut off, and the purging work cannot be performed.

[0054] Optionally, the exhaust aftertreatment system further includes a control unit 5; the control unit 5 is respectively connected to the urea nozzle 12, the control valve 23, and the high-pressure pump 22, and is configured to control the opening of the control valve 23 and the start-up of the high-pressure pump 22 according to the completion of injection of the urea nozzle 12.

[0055] Specifically, the exhaust gas after-treatment system further includes a control unit 5 , which can control the working states of the urea nozzle 12 , the control valve 23 and the high-pressure pump 22 according to different working conditions. Specifically, under the urea injection operating condition, the control unit 5 controls the urea nozzle 12 to operate, the control valve 23 is closed, and the high-pressure pump 22 does not operate. At this time, urea solution can be injected into the catalyst through the liquid injection channel 121 of the urea nozzle 12, and no high-pressure gas is input into the gas purge channel 122. Under the urea injection completion operating condition, the control unit 5 controls the urea nozzle 12 to stop operating, the control valve 23 is opened, and the high-pressure pump 22 is started. At this time, the urea solution is no longer input into the liquid injection channel 121, and the gas output from the air filter 21 can flow into the high-pressure pump 22 along the branch pipeline. The high-pressure pump 22 pressurizes the gas and transports it to the gas purge channel 122. Since the gas purge channel 122 is connected to the liquid injection channel 121, high-pressure purge of the liquid injection channel 121 can be achieved to remove the residual urea solution in the liquid injection channel 121.

[0056] An embodiment of the present application further provides a vehicle, comprising the urea nozzle 12 or the exhaust after-treatment system as described above.

[0057] The advantages of the vehicle, the exhaust after-treatment system, and the urea nozzle 12 over the prior art are the same and will not be described in detail here.

[0058] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0059] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the terms "include", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device that includes a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, an element defined by the phrase "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or terminal device that includes the element.

[0060] The technical solutions provided by this application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of this application. The description of the above embodiments is only intended to help understand this application, and the contents of this specification should not be construed as limiting this application. At the same time, for those skilled in the art, according to this application, there may be various changes in the specific implementation methods and application scopes. It is not necessary and impossible to list all implementation methods here, and obvious changes or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A urea nozzle, characterized in that: include: a main body portion, wherein a liquid injection channel and a gas purge channel are formed inside the main body portion; The inlet end of the liquid injection channel is connected to the liquid storage assembly, and the outlet end of the liquid injection channel is connected to the catalytic reaction module; The inlet end of the gas purge channel is connected to a gas supply module, which is used to provide high-pressure gas; the outlet end of the gas purge channel is connected to the liquid injection channel, so that the high-pressure gas enters the liquid injection channel and purges the liquid injection channel.

2. The urea nozzle according to claim 1, characterized in that: The axis of the gas purge channel is arranged at an angle to the axis of the liquid injection channel.

3. The urea nozzle according to claim 2, characterized in that: The angle between the axis of the gas purge channel and the axis of the liquid injection channel is set to 15° to 30°.

4. The urea nozzle according to claim 1, characterized in that: The inlet end of the gas purge channel and the inlet end of the liquid injection channel are arranged on the same side of the main body.

5. The urea nozzle according to claim 1, characterized in that: The inlet end of the gas purge channel and the outlet end of the liquid injection channel are arranged on the same side of the main body.

6. An exhaust after-treatment system comprising a urea supply module, a catalytic reaction module and a muffler module, characterized in that: The urea supply module includes the urea nozzle according to any one of claims 1 to 5.

7. The exhaust aftertreatment system according to claim 6, characterized in that: The exhaust after-treatment system further includes a gas supply module; The gas supply module includes an air filter and a high-pressure pump. The output end of the air filter is connected to the input end of the high-pressure pump, and the output end of the high-pressure pump is connected to the inlet end of the gas purge channel.

8. The exhaust aftertreatment system according to claim 7, characterized in that: A control valve is provided between the output end of the air filter and the input end of the high-pressure pump.

9. The exhaust aftertreatment system according to claim 8, characterized in that: The exhaust after-treatment system further includes a control unit; The control unit is connected to the urea nozzle, the control valve, and the high-pressure pump, respectively, and is configured to control the opening of the control valve and the starting of the high-pressure pump according to the completion of injection of the urea nozzle.

10. A vehicle, characterized in that: The method comprises the urea nozzle according to any one of claims 1 to 5, or the exhaust gas after-treatment system according to any one of claims 6 to 9.

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