Urea injection assembly, urea nozzle anti-freezing method and vehicle

Abstract

The application belongs to the technical field of exhaust treatment, and discloses a urea injection assembly, a urea nozzle anti-freezing method and a vehicle. The urea injection assembly comprises a urea nozzle and a heat dissipation piece arranged on the side of the urea nozzle. A driving unit is arranged between the urea nozzle and the heat dissipation piece, and is used for driving the heat dissipation piece to move and switch between a first working position and a second working position. When the heat dissipation piece is located at the first working position, the heat dissipation piece is attached to the urea nozzle. When the heat dissipation piece is located at the second working position, the heat dissipation piece is separated from the urea nozzle. The urea nozzle anti-freezing method comprises the following steps: controlling the urea nozzle to work and obtaining control parameters, the control parameters comprising at least one of an ambient temperature A, a urea injection amount B, a temperature before SCR C, a vehicle speed signal D and an exhaust gas volume flow E, and determining whether the urea nozzle needs to be cooled by the heat dissipation piece according to the value of the control parameters. The vehicle comprises the urea injection assembly. The urea injection assembly can avoid the urea nozzle from freezing and ensure the effective injection of the urea nozzle.

Description

Technical Field

[0001] This invention relates to the field of exhaust gas treatment technology, and in particular to a method for preventing urea nozzles from freezing and a urea nozzle. Background Technology

[0002] To meet increasingly stringent emission regulations, the SCR system in diesel vehicles is a highly efficient way to eliminate NO. x Exhaust gas aftertreatment technology has been widely applied. Currently, diesel engine SCR systems commonly use urea aqueous solution as a reducing agent additive. Urea injectors are needed to inject this urea aqueous solution into the aftertreatment process. The urea injector uses a solenoid valve to control the opening and closing of the valve core, thereby achieving urea injection.

[0003] Because the urea nozzle is located on the aftertreatment system, the temperature near the nozzle is relatively high. Therefore, cooling is necessary to prevent the urea nozzle from overheating. In existing technologies, urea nozzles are generally equipped with heat sinks for cooling. However, when diesel vehicles are used in cold regions, the urea nozzle cools down rapidly due to the low ambient temperature, which can lead to icing. This icing hinders effective urea injection and affects the reliability of the exhaust aftertreatment system. Summary of the Invention

[0004] The purpose of this invention is to provide a urea injection assembly that can prevent its injection nozzle from freezing and ensure effective urea injection.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A urea injection assembly, comprising:

[0007] Urea nozzle;

[0008] A heat sink is disposed on the periphery of the urea nozzle. A drive unit is provided between the urea nozzle and the heat sink, and the drive unit is used to drive the heat sink to move and switch between a first station and a second station.

[0009] When the heat sink is located at the first station, the heat sink is in contact with the urea nozzle;

[0010] When the heat sink is located at the second station, the heat sink is separated from the urea nozzle.

[0011] Preferably, the drive unit includes a movable rod, the first end of which is rotatably connected to the periphery of the urea nozzle, and the second end of which is connected to the heat sink; the movable rod is rotatable relative to the urea nozzle to allow the heat sink to move and switch between the first station and the second station.

[0012] Preferably, the drive unit further includes a drive motor disposed between the urea nozzle and the first end of the movable rod, the drive motor being used to drive the movable rod to rotate.

[0013] Preferably, a connecting rod is fixedly provided on the urea nozzle, the connecting rod extends outward relative to the urea nozzle, and the first end of the movable rod is rotatably connected to the connecting rod.

[0014] Preferably, one of the urea nozzle and the heat sink is provided with a permanent magnet, and the other is provided with an electromagnet with variable magnetic poles.

[0015] Preferably, the heat sink is configured as a heat sink fin.

[0016] The present invention also provides a method for preventing urea nozzle from freezing. By using the above-mentioned urea injection assembly, the urea nozzle can be prevented from freezing and the effective injection of urea can be guaranteed.

[0017] A method for preventing urea nozzle freezing, using the urea injection assembly described in any of the above claims, the method comprising the following steps:

[0018] S100: Control the urea nozzle to operate;

[0019] S200. Obtain control parameters, wherein the control parameters include at least one of ambient temperature A, urea injection quantity B, SCR inlet temperature C, vehicle speed signal D, and exhaust gas volume flow rate E.

[0020] S300: Determine whether the urea nozzle needs to dissipate heat through the heat sink based on the value of the control parameter;

[0021] If so, control the heat sink to move to the first working position;

[0022] If not, control the heat sink to move to the second station.

[0023] Preferably, step S300 specifically includes:

[0024] S310. Determine whether the ambient temperature A is greater than the threshold temperature A1; if yes, proceed to step S340; if no, proceed to step S320.

[0025] S320. Determine whether the urea injection volume B is less than the threshold injection volume B1; if yes, proceed to step S330; if no, proceed to step S340.

[0026] S330. Determine whether the SCR inlet temperature C is less than the threshold temperature C1, or whether the vehicle speed signal D is greater than the threshold vehicle speed D1, or whether the exhaust gas volume flow rate E is less than the threshold volume flow rate E1; if yes, proceed to step S350; if no, proceed to step S340.

[0027] S340, Control the heat sink to move to the first work station;

[0028] S350, Control the heat sink to move to the second work station.

[0029] Preferably, in step S200, the ambient temperature A and the SCR inlet temperature C are obtained by a temperature sensor, the urea injection quantity B and the exhaust gas volume flow rate E are obtained by a flow sensor, and the vehicle speed D is obtained by a speed sensor.

[0030] The present invention also provides a vehicle in which the above-mentioned urea injection assembly is applied, which can prevent the injection nozzle from freezing and ensure effective injection of urea.

[0031] A vehicle comprising:

[0032] SCR system, including urea nozzle;

[0033] As described in any of the preceding claims, the urea nozzle is disposed on the urea spray pipe.

[0034] Beneficial effects:

[0035] This invention provides a urea injection assembly. A heat sink is mounted on the urea nozzle, and a drive unit is located between the urea nozzle and the heat sink. The drive unit moves the heat sink between a first station and a second station. Specifically, when the heat sink is in the first station, it is in contact with the urea nozzle; when the heat sink is in the second station, it is separated from the urea nozzle. Specifically, when the heat sink is in the first station, it is in contact with the urea nozzle to exchange heat, thereby absorbing heat from the urea nozzle for normal cooling and preventing overheating. When the heat sink is in the second station, it is separated from the urea nozzle, reducing the cooling effect and preventing the urea nozzle from cooling down too quickly and freezing. This urea injection assembly has a simple structure, prevents icing of the urea nozzle, and ensures effective urea injection.

[0036] The urea nozzle anti-freezing method provided by this invention utilizes the aforementioned urea injection assembly. First, the urea nozzle is controlled to operate. During operation, control parameters are acquired, including at least one of the following: ambient temperature (A), urea injection volume (B), SCR inlet temperature (C), vehicle speed signal (D), and exhaust gas volumetric flow rate (E). The values ​​of these parameters are used to determine whether the urea nozzle requires cooling. Based on the values ​​of A, B, C, D, and E, if it is determined that normal cooling of the urea nozzle is necessary, the heat sink is moved to the first position. If it is determined that excessively rapid cooling of the urea nozzle is to be avoided, and the heat sink is not needed temporarily, the heat sink is moved to the second position. This method can adaptively adjust the position of the heat sink in real time based on the ambient temperature, urea injection volume, SCR inlet temperature, vehicle speed signal, and exhaust gas volumetric flow rate, thus preventing urea nozzle icing and ensuring effective urea injection.

[0037] The present invention also provides a vehicle, the vehicle including an SCR system and the above-mentioned urea injection assembly. The SCR system includes a urea injection pipe and a urea nozzle disposed on the urea injection pipe, which also has the function of preventing the urea nozzle from freezing and ensuring the effective injection of the urea nozzle. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the heat dissipation component of the urea injection assembly provided by the present invention located at the first station relative to the urea nozzle;

[0039] Figure 2 This is a schematic diagram of the heat dissipation component of the urea injection assembly provided by the present invention located at the second position relative to the urea nozzle;

[0040] Figure 3 This is a flowchart of the urea nozzle antifreeze method provided by the present invention;

[0041] Figure 4 This is a flowchart detailing some aspects of the urea nozzle antifreeze method provided by the present invention.

[0042] In the picture:

[0043] 1. Urea nozzle; 11. Permanent magnet;

[0044] 2. Heat dissipation components;

[0045] 3. Movable lever;

[0046] 4. Connecting rod. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0048] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0050] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0051] This invention provides a urea injection assembly, as shown in the reference. Figures 1 to 2 As shown, it includes a urea nozzle 1 and a heat sink 2. The heat sink 2 is disposed around the urea nozzle 1. A drive unit (not shown) is disposed between the urea nozzle 1 and the heat sink 2. The drive unit is used to drive the heat sink 2 to move and switch between a first station and a second station. When the heat sink 2 is in the first station, the heat sink 2 is in contact with the urea nozzle 1; when the heat sink 2 is in the second station, the heat sink 2 is separated from the urea nozzle 1.

[0052] Specifically, when the heat sink 2 is in the first position, it is attached to the urea nozzle 1, exchanging heat to absorb heat from the nozzle and thus providing normal cooling and preventing overheating. When the heat sink 2 is in the second position, it separates from the nozzle 1, reducing its cooling effect and preventing the nozzle 1 from cooling down too quickly and freezing. This urea injection assembly has a simple structure, prevents the nozzle 1 from freezing, and ensures effective injection.

[0053] Furthermore, the drive unit includes a movable rod 3. The first end of the movable rod 3 is rotatably connected to the urea nozzle 1, and the second end of the movable rod 3 is connected to the heat sink 2. The movable rod 3 can rotate relative to the urea nozzle 1 to allow the heat sink 2 to move and switch between a first station and a second station. Specifically, when the heat sink 2 needs to move to the first station, the movable rod 3 rotates towards the direction closer to the urea nozzle 1, so that the heat sink 2 moves to the first station and comes into contact with the urea nozzle 1; when the heat sink 2 needs to move to the second station, the movable rod 3 rotates away from the urea nozzle 1, so that the heat sink 2 moves to the second station and releases contact with the urea nozzle 1.

[0054] In this embodiment, the heat sink 2 is configured as a heat sink. The heat sink is preferably made of copper, copper-aluminum alloy, iron, aluminum, graphite, etc.

[0055] Furthermore, the drive unit also includes a drive motor disposed between the urea nozzle 1 and the first end of the movable rod 3, the drive motor being used to drive the movable rod 3 to rotate. Specifically, the housing of the drive motor is fixedly connected to the urea nozzle 1, and the output shaft of the drive motor is fixedly connected to the movable rod 3, the rotation of the output shaft of the drive motor can drive the movable rod 3 to rotate.

[0056] More specifically, a connecting rod 4 is fixedly installed on the urea nozzle 1, extending outward relative to the urea nozzle 1. The first end of the movable rod 3 is rotatably connected to the connecting rod 4. The installation of the connecting rod 4 increases the distance between the rotating end of the movable rod 3 and the urea nozzle 1, ensuring the rotation range of the movable rod 3, and thus ensuring the reliable movement of the heat sink 2.

[0057] As an optional implementation, a drive motor is not required. One of the urea nozzle 1 and the heat sink 2 is equipped with a permanent magnet 11, and the other with an electromagnet with variable poles. When the heat sink 2 needs to move to the first position, the electromagnet's poles are adjusted to attract the permanent magnet 11, causing the permanent magnet 11 to adhere to the electromagnet. When the heat sink 2 needs to move to the second position, the electromagnet's poles are adjusted to repel the permanent magnet 11, causing the permanent magnet 11 to release from the electromagnet. Specifically, according to Ampere's law, a magnetic field exists around a current-carrying conductor, and the direction of the magnetic field is changed by changing the direction of the current. By changing the direction of the current flowing through the electromagnet, the magnetic poles generated by the electromagnet are correspondingly changed. Specifically, when the heat sink 2 needs to be moved to the first station, the direction of the current flowing through the electromagnet is adjusted so that the magnetic poles of the electromagnet are opposite to those of the permanent magnet 11, thereby attracting the electromagnet and the permanent magnet 11 so that the permanent magnet 11 is attracted and attached to the electromagnet, driving the movable rod 3 to rotate toward the direction closer to the urea nozzle 1 so that the heat sink 2 moves and is held in the first station.

[0058] When the heat sink 2 needs to be moved to the second station, the direction of the current flowing through the electromagnet is adjusted so that the magnetic poles of the electromagnet are connected to the magnetic poles of the permanent magnet 11, thereby causing the electromagnet and the permanent magnet 11 to repel each other, driving the movable rod 3 to rotate away from the urea nozzle 1, so that the heat sink 2 moves to the second station and releases the contact between it and the urea nozzle 1.

[0059] It is worth mentioning that the direction of the current flowing through the electromagnet can also be changed through a corresponding controller, which is existing technology and will not be elaborated on here.

[0060] This embodiment also provides a method for preventing urea nozzles from freezing. (Refer to...) Figures 1 to 4 As shown, the method for preventing urea nozzles from freezing mainly includes the following steps:

[0061] S100, Control the operation of urea nozzle 1;

[0062] S200. Acquire control parameters, including at least one of the following: ambient temperature A, urea injection quantity B, SCR inlet temperature C, vehicle speed signal D, and exhaust gas volumetric flow rate E.

[0063] S300. Determine whether urea nozzle 1 needs to dissipate heat through heat sink 2 based on the value of the control parameters.

[0064] If so, control the heat sink 2 to move to the first working position;

[0065] If not, control the heat sink 2 to move to the second station.

[0066] In this embodiment, it is necessary to determine whether the urea nozzle 1 needs to be cooled by the heat sink 2 based on the value of at least one of the control parameters A, B, C, D, and E. If it is determined that normal cooling of the urea nozzle 1 is required, the heat sink 2 is moved to the first position. If it is determined that the urea nozzle 1 needs to be cooled down temporarily to avoid excessive cooling, the heat sink 2 is moved to the second position. This method can adaptively adjust the position of the heat sink 2 in real time based on the ambient temperature, urea injection volume, SCR inlet temperature, vehicle speed signal, and exhaust gas volume flow rate, which can prevent the urea nozzle 1 from freezing and ensure effective injection of the urea nozzle 1.

[0067] In this embodiment, step S300 specifically includes:

[0068] S310. Determine whether the ambient temperature A is greater than the threshold temperature A1; if yes, proceed to step S340; if no, proceed to step S320.

[0069] S320. Determine whether the urea injection volume B is less than the threshold injection volume B1; if yes, proceed to step S330; if no, proceed to step S340.

[0070] S330. Determine whether the SCR inlet temperature C is less than the threshold temperature C1, or whether the vehicle speed signal D is greater than the threshold vehicle speed D1, or whether the exhaust gas volume flow rate E is less than the threshold volume flow rate E1; if yes, proceed to step S350; if no, proceed to step S340.

[0071] S340, control the heat sink 2 to move to the first station;

[0072] S350, control the heat sink 2 to move to the second station.

[0073] Specifically, after obtaining the values ​​of A, B, C, D, and E, step S310 is first performed to determine whether the ambient temperature A is greater than the threshold temperature A1. If yes, it indicates that the ambient temperature is currently high and will not cause the urea nozzle 1 to cool down too quickly, meaning that the urea nozzle 1 will not freeze. At this point, step S340 is performed to control the heat sink 2 to move to the first station, where the heat sink 2 and the urea nozzle 1 make normal contact and exchange heat, thereby cooling the urea nozzle 1 normally and preventing it from overheating. If no, it indicates that the ambient temperature is currently lower than the threshold temperature A1, and the next step is to further perform step S320 to determine whether the urea injection volume B is less than the threshold injection volume B1.

[0074] Specifically, since the temperature of urea is generally between 80℃ and 110℃, if the urea nozzle 1 sprays a sufficient amount, that is, when the urea nozzle 1 sprays at the threshold spray volume B1, the temperature of the urea nozzle 1 will not freeze. Therefore, in step S320, if the determination is negative, it indicates that the urea spray volume is not less than the threshold, the urea is sprayed normally and in sufficient quantity, and the urea nozzle 1 will not freeze. At this time, step S340 is performed to control the heat sink 2 to move to the first station. The heat sink 2 and the urea nozzle 1 make normal contact and exchange heat, thereby cooling the urea nozzle 1 normally and preventing the urea nozzle 1 from overheating. If the determination is positive, it further indicates that the urea nozzle 1 spray volume is insufficient. At this time, step S330 needs to be performed to determine whether the SCR inlet temperature C is less than the threshold temperature C1, or whether the vehicle speed signal D is greater than the threshold vehicle speed D1, or whether the exhaust gas volume flow rate E is less than the threshold volume flow rate E1.

[0075] Specifically, the temperature before the SCR system also affects the temperature of the urea nozzle 1. If the temperature before the SCR system is high enough, as shown in this embodiment (not less than the threshold temperature C1), it indicates that the urea nozzle 1 is in a high-temperature environment and will not freeze. Vehicle speed also affects the urea nozzle 1. If the vehicle speed is slow, as shown in this embodiment (not greater than the threshold speed D1), the wind speed around the urea nozzle is low, and the cooling effect of the ambient wind is limited, so it will not cause the urea nozzle 1 to freeze. Because the exhaust gas temperature from the SCR system is high, if the exhaust gas volumetric flow rate is not less than the threshold volumetric flow rate E1, the urea nozzle 1 will not freeze due to the exhaust gas. In step S330, if at least one of the following three conditions is met: the SCR pre-temperature C is less than the threshold temperature C1, the vehicle speed signal D is greater than the threshold vehicle speed D1, and the exhaust gas volume flow rate E is less than the threshold volume flow rate E1, then combined with the judgment results of steps S310 and S320, i.e., the ambient temperature is lower than the threshold temperature A1, and whether the urea injection quantity B is less than the threshold injection quantity B1, it indicates that the urea nozzle 1 is in a state that is prone to freezing. If the urea nozzle 1 continues to be cooled normally, it will cause the urea nozzle 1 to cool down further and freeze. At this time, step S350 is performed, controlling the heat sink 2 to move to the second station, separating the heat sink 2 from the urea nozzle 1, and releasing the heat sink 2 from the urea nozzle 1 to prevent the urea nozzle 1 from cooling down further and avoid freezing due to overcooling. If the following three conditions are met simultaneously: the SCR inlet temperature C is not less than the threshold temperature C1, the vehicle speed signal D is not greater than the threshold vehicle speed D1, and the exhaust gas volume flow rate E is not less than the threshold volume flow rate E1, it indicates that even if the ambient temperature is lower than the threshold temperature A1 and the urea injection quantity B is less than the threshold injection quantity B1, the urea nozzle 1 will not be overcooled under the influence of the above three factors. At this time, step S340 is performed, controlling the heat sink 2 to move to the first station, and the heat sink 2 and the urea nozzle 1 make normal contact to exchange heat, so as to perform normal cooling and heat dissipation on the urea nozzle 1.

[0076] In this embodiment, the specific values ​​of threshold temperature A1, threshold injection volume B1, threshold temperature C1, threshold vehicle speed D1, and threshold volumetric flow rate E1 are all adaptively adjusted according to the actual settings, and are not limited in detail here.

[0077] Specifically, in step S200, the ambient temperature A and the temperature C before the SCR are obtained by a temperature sensor. Optionally, the temperature sensor is preferably a non-contact temperature sensor such as an ultrasonic temperature sensor or a laser temperature sensor.

[0078] Specifically, in step S200, the urea injection quantity B and the exhaust gas volumetric flow rate E are obtained through a flow sensor. Optionally, the urea injection quantity can be detected using a magnetic flow sensor, ultrasonic flow sensor, or the like. The exhaust gas volumetric flow rate can be detected using a semiconductor gas flow sensor, electrochemical gas flow sensor, or the like.

[0079] Specifically, in step S200, the vehicle speed D is obtained through a speed sensor. Optionally, the vehicle speed can be detected using a magnetoelectric vehicle speed sensor, a Hall effect vehicle speed sensor, a photoelectric vehicle speed sensor, etc.

[0080] Specifically, the drive motor is communicatively connected to the controller. The controller has pre-set threshold temperatures A1, B1, C1, D1, and E1. The controller acquires the ambient temperature A, urea injection quantity B, SCR inlet temperature C, threshold vehicle speed D1, and threshold volumetric flow rate E1 through temperature, flow, and speed sensors. Steps S310 to S350 are all controlled by the controller. For example, taking the initial position of the heat sink 2 at the first station as an example, when the controller determines that the ambient temperature A is not greater than the threshold temperature A1, the urea injection quantity B is less than the threshold injection quantity B1, and at least one of the following three conditions is met: the SCR inlet temperature C is less than the threshold temperature C1, the vehicle speed signal D is greater than the threshold vehicle speed D1, and the exhaust gas volumetric flow rate E is less than the threshold volumetric flow rate E1, the controller controls the drive motor to rotate, causing the drive motor to rotate the movable rod 3 away from the urea nozzle 1, thus moving the heat sink 2 from the first station to the second station.

[0081] In this embodiment, the controller is set as a PLC controller.

[0082] This embodiment also provides a vehicle, which includes an SCR system and the aforementioned urea injection assembly. The SCR system includes a urea injection pipe, and the urea nozzle 1 is disposed on the urea injection pipe, which also has the function of preventing the urea nozzle 1 from freezing and ensuring the effective injection of the urea nozzle 1.

[0083] In summary, the urea injection assembly provided in this embodiment, by driving the heat sink 2 to move and switch between the first and second positions via a drive unit, can prevent the urea nozzle 1 from freezing and ensure effective injection of the urea nozzle 1. The urea nozzle anti-freezing method provided in this embodiment, using the aforementioned urea injection assembly, can adaptively adjust the position of the heat sink 2 in real time based on ambient temperature, urea injection volume, SCR inlet temperature, vehicle speed signal, and exhaust gas volumetric flow rate, thus preventing the urea nozzle 1 from freezing and ensuring effective injection of the urea nozzle 1. This embodiment also provides a vehicle including an SCR system and the aforementioned urea injection assembly, which also has the effect of preventing the urea nozzle 1 from freezing and ensuring effective injection of the urea nozzle 1.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A urea injection assembly, characterized in that, include: Urea nozzle (1); A heat sink (2) is disposed on the periphery of the urea nozzle (1), and a drive unit is disposed between the urea nozzle (1) and the heat sink (2). The drive unit is used to drive the heat sink (2) to move and switch between a first station and a second station; wherein, When the heat sink (2) is located at the first work station, the heat sink (2) is in contact with the urea nozzle (1); When the heat sink (2) is located at the second working position, the heat sink (2) is separated from the urea nozzle (1); The drive unit includes a movable rod (3), the first end of which is rotatably connected to the periphery of the urea nozzle (1), and the second end of which is connected to the heat sink (2); the movable rod (3) can rotate relative to the urea nozzle (1) to allow the heat sink (2) to move and switch between the first station and the second station; The drive unit also includes a drive motor disposed between the urea nozzle (1) and the first end of the movable rod (3), the drive motor being used to drive the movable rod (3) to rotate.

2. The urea injection assembly according to claim 1, characterized in that, A connecting rod (4) is fixedly installed on the urea nozzle (1). The connecting rod (4) extends outward relative to the urea nozzle (1), and the first end of the movable rod (3) is rotatably connected to the connecting rod (4).

3. The urea injection assembly according to claim 1, characterized in that, One of the urea nozzle (1) and the heat sink (2) is provided with a permanent magnet (11), and the other is provided with an electromagnet with variable magnetic poles.

4. The urea injection assembly according to any one of claims 1-3, characterized in that, The heat sink (2) is configured as a heat sink.

5. A method for preventing urea nozzles from freezing, characterized in that, The urea nozzle antifreeze method, using the urea injection assembly as described in any one of claims 1-4, comprises the following steps: S100, Control the urea nozzle (1) to work; S200. Obtain control parameters, wherein the control parameters include at least one of ambient temperature A, urea injection quantity B, SCR inlet temperature C, vehicle speed signal D, and exhaust gas volume flow rate E. S300. Determine whether the urea nozzle (1) needs to dissipate heat through the heat sink (2) based on the value of the control parameter. If so, control the heat sink (2) to move to the first working position; If not, control the heat sink (2) to move to the second station; The specific steps of S300 are as follows: S310. Determine whether the ambient temperature A is greater than the threshold temperature A1; if yes, proceed to step S340; if no, proceed to step S320. S320. Determine whether the urea injection volume B is less than the threshold injection volume B1; if yes, proceed to step S330; if no, proceed to step S340. S330. Determine whether the SCR inlet temperature C is less than the threshold temperature C1, or whether the vehicle speed signal D is greater than the threshold vehicle speed D1, or whether the exhaust gas volume flow rate E is less than the threshold volume flow rate E1; if yes, proceed to step S350; if no, proceed to step S340. S340, Control the heat sink (2) to move to the first work station; S350, control the heat sink (2) to move to the second work station.

6. The method for preventing urea nozzle freezing according to claim 5, characterized in that, In step S200, the ambient temperature A and the SCR inlet temperature C are obtained through a temperature sensor, the urea injection quantity B and the exhaust gas volume flow rate E are obtained through a flow sensor, and the vehicle speed D is obtained through a speed sensor.

7. A vehicle, characterized in that, include: SCR system, including urea nozzle; The urea injection assembly as described in any one of claims 1-4, wherein the urea nozzle (1) is disposed on the urea injection pipe.

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