Ultrasonic urea spraying device

Abstract

The utility model relates to the field of tail gas after-treatment devices, and particularly discloses an ultrasonic urea spraying device which comprises a shell composed of a cover body and a box body, an inner cavity and a cooling channel are arranged in the box body, and a spraying pipe is installed in the inner cavity in a suspended state through a first elastic part and a second elastic part. An energy conversion device consisting of a piezoelectric ceramic ring and an electrode plate is mounted on the spray pipe, so that the spray pipe oscillates to generate ultrasonic waves, liquid particles are crushed and refined, the granularity is reduced, the atomization effect is improved, the atomization effect is controlled by ultrasonic frequency and is not influenced by liquid inlet pressure, and the adaptive range is wider; when the spray pipe oscillates, crystals in the pipeline can be broken through vibration, heat can be generated through friction at the contact position, when the external temperature changes, the device can keep the stable temperature by changing the liquid flow in the cooling channel, the crystals can be relieved, and the performance can be kept stable through cooling.

Description

Technical Field

[0001] This utility model belongs to the field of exhaust gas aftertreatment devices, and specifically relates to an ultrasonic urea injection device. Background Technology

[0002] Due to changes in vehicle emission regulations, the China VI B and China VII emission standards have imposed stricter requirements on NOx emissions. These requirements can no longer be met solely through engine manufacturing processes and system calibration management. A urea atomization injection system with a larger urea supply, superior atomization performance, and high conversion efficiency is needed to match these standards. Traditional urea nozzles typically produce atomized particles between 0.85 and 2.8 mm, and their atomization effect is highly dependent on the inlet pressure. Theoretically, higher pressure results in better atomization. However, the pressure rating range for each urea nozzle is relatively small, making it impossible to achieve optimal atomization within this limited range. Furthermore, excessively high or low pressure can affect the uniformity of atomized particles. Additionally, at low temperatures or in narrow channels, urea crystals can easily form inside the nozzle, causing blockage. Therefore, there is an urgent need to develop a urea nozzle with better atomization performance, a wider adaptability, and improved anti-crystallization capabilities to meet the requirements of the new national emission standards.

[0003] A phased-array ultrasonic atomizing nozzle is disclosed in patent document application number "CN201010122838.X", comprising: a front cover, a rear cover, and a phased-array high-frequency ultrasonic transducer array. The phased-array high-frequency ultrasonic transducer array includes a support member, several array elements, and a phased-array excitation device for driving the array elements. The support member has several holes, with one array element in each hole. All array elements are distributed in a ring array with equal spacing in groups. The support member with the array elements, the front cover, and the rear cover form a sandwich structure. The tip of the amplitude transformer is the liquid atomization surface, and the liquid to be atomized reaches its surface through the central channel. Although the ultrasonic atomizing nozzle in this prior art can effectively improve the atomization effect, if applied to SCR urea injection, it still cannot avoid the problem of urea crystallization due to low temperature and narrow channel. Furthermore, it lacks heat dissipation and flow control devices, which can cause unstable urea injection volume and high failure rate. Therefore, it cannot be used directly under SCR operating conditions.

[0004] The above background information is provided only to assist in understanding the utility model concept and technical solution of this utility model, and it does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] The purpose of this invention is to provide an ultrasonic urea injection device, thereby overcoming the shortcomings of existing urea nozzles such as poor atomization effect, narrow adaptability range, and easy crystallization and clogging.

[0006] To achieve the above objectives, this utility model provides an ultrasonic urea injection device, comprising: a housing; an inner cavity within the housing; a liquid inlet channel at the top of the inner cavity; a nozzle within the inner cavity; one end of the nozzle communicating with the liquid inlet channel; and the other end of the nozzle extending outward from the bottom of the housing. Alternatingly stacked piezoelectric ceramic rings and electrode plates are fitted around the nozzle. The top and bottom of the inner cavity are respectively provided with a first mounting hole and a second mounting hole. The first mounting hole communicates with the liquid inlet channel, and a cooling channel is provided around the outside of the second mounting hole. A main water channel is also provided within the housing. One end of the main waterway is provided with a water inlet connector, and the other end of the main waterway is provided with a first branch waterway and a second branch waterway. The first branch waterway is connected to the liquid inlet channel with a metering valve and a pressure stabilizing chamber. The second branch waterway is connected to one end of the cooling channel, and the other end of the cooling channel is provided with a return connector. The rod of the nozzle can be fitted into the first mounting hole and the second mounting hole and can slide along the axis of the nozzle. The nozzle is provided with a first elastic part and a second elastic part between the top and bottom of the inner cavity, respectively. The first elastic part and the second elastic part can cause the nozzle to generate elastic vibration in the axial direction.

[0007] Preferably, in the above technical solution, a baffle is fixedly provided on the nozzle, and a stepped shaft is provided at the bottom of the baffle. The stepped shaft is slidably fitted into the second mounting hole. The second elastic part is an annular structure and is fitted around the outer periphery of the stepped shaft. The second elastic part can simultaneously abut against the bottom of the baffle and the bottom of the inner cavity and be elastically compressed.

[0008] Preferably, in the above technical solution, a detachable retaining ring is fitted on the nozzle, the piezoelectric ceramic ring and the electrode plate are located between the retaining ring and the baffle, a locking nut is provided on the top of the retaining ring, and the locking nut is threadedly connected to the body of the nozzle; one end of the nozzle is slidably fitted into the first mounting hole, the first elastic part is an annular structure and fitted on the outer periphery of one end of the nozzle, and the first elastic part can simultaneously abut against the top of the locking nut and the top of the inner cavity and be elastically compressed.

[0009] Preferably, in the above technical solution, an inwardly recessed limiting groove is provided at the top of the inner cavity, the first mounting hole is opened in the limiting groove, and the outer periphery of the first elastic part can be locked in the limiting groove.

[0010] Preferably, in the above technical solution, the shell is assembled from a cover and a box, the inner cavity and the cooling channel are formed in the box, the liquid inlet channel, the main water channel, the first branch water channel and the second branch water channel are formed on the cover, and the cover and the box are assembled by bolts.

[0011] Preferably, in the above technical solution, the housing is provided with a first connecting channel and a second connecting channel, the axes of the first connecting channel and the second connecting channel are parallel to the axis of the inner cavity, one end of the first connecting channel is connected to one end of the cooling channel, and one end of the second connecting channel is connected to the other end of the cooling channel; the cover is provided with a reflux hole, one end of the reflux hole is connected to the other end of the second connecting channel, the reflux connector is installed at the other end of the reflux hole, and the other end of the first connecting channel is connected to the second water distribution channel.

[0012] Preferably, in the above technical solution, the top of the cover is provided with a boss, the main water channel, the first branch water channel and the second branch water channel are all located in the boss, and the side of the boss is provided with a third mounting hole, which communicates with the first branch water channel.

[0013] Preferably, in the above technical solution, the pressure stabilizing chamber is detachably installed on the cover, the bottom of the pressure stabilizing chamber is connected to one end of the liquid inlet channel, a fourth mounting hole is provided on the side of the pressure stabilizing chamber, one end of the metering valve is fixedly connected to the third mounting hole, and the other end of the metering valve is fixedly connected to the fourth mounting hole.

[0014] Preferably, in the above technical solution, a sealing ring is provided between the other end of the metering valve and the fourth mounting hole.

[0015] Preferably, in the above technical solution, the bottom of the housing is provided with a mounting base, the outer periphery of the mounting base is provided with a mounting flange, the mounting base is provided with a through hole, the other end of the nozzle passes through the through hole and extends out from the bottom of the mounting base, and the diameter of the other end of the nozzle gradually decreases and is provided with a conical nozzle.

[0016] Compared with existing technologies, this utility model has the following beneficial effects:

[0017] 1. The ultrasonic urea injection device of this utility model uses a nozzle with a suspension structure and a transducer consisting of a piezoelectric ceramic ring and electrode plates installed on the nozzle to generate ultrasonic waves through nozzle oscillation. This breaks down and refines liquid particles, reducing particle size and improving atomization. The atomization effect is controlled by the ultrasonic frequency and is not affected by the inlet pressure, thus having a wider range of applications. After urea enters the main water channel, it can be diverted into the inlet channel and the cooling channel. When the nozzle oscillates, it can not only break up crystals in the pipe but also generate heat through friction at the contact point. When the external temperature changes, the device can maintain a stable temperature by changing the liquid flow rate in the cooling channel, which can both alleviate crystallization and cool down to maintain stable performance.

[0018] 2. The first and second elastic parts of the annular structure in this utility model can not only provide elastic support for the nozzle in the axial direction, providing a certain amount of elastic displacement during oscillation, but also seal the first and second mounting holes to prevent liquid in the inlet channel and aerosol in the SCR from entering the inner cavity and affecting the circuit at the electrode plate.

[0019] 3. In this utility model, one end of the nozzle is slidably inserted into the first mounting hole, and the first mounting hole is connected to the liquid inlet channel. The urea liquid can cool the friction part between the first mounting hole and the outer side of one end of the nozzle, and can also absorb heat to prevent crystallization under cold conditions.

[0020] 4. The locking nut in this utility model can not only lock the retaining ring, but its top can also abut against the first elastic part to limit the assembly of the nozzle.

[0021] 5. The pressure stabilizing chamber in this utility model can not only stabilize the liquid pressure in the inlet channel, but also reverse the flow direction of the liquid, thereby saving lateral installation space and making the overall structure more compact; the detachable design of the pressure stabilizing chamber makes it easier to disassemble and assemble when replacing or repairing the metering valve, which is convenient for maintenance. Attached Figure Description

[0022] Figure 1 This is a structural diagram of the ultrasonic urea injection device of this utility model.

[0023] Figure 2 This is a partial cross-sectional view of the ultrasonic urea injection device between the pressure stabilizing chamber and the main waterway.

[0024] Figure 3 This is a partial cross-sectional view of the ultrasonic urea injection device between the pressure stabilizing chamber and the reflux orifice.

[0025] Explanation of key figure labels:

[0026] 100-Shell, 101-Cover, 102-Box, 110-Inner cavity, 111-First mounting hole, 112-Second mounting hole, 113-Limiting groove, 120-Liquid inlet channel, 130-Boss, 131-Main water channel, 132-First branch water channel, 133-Second branch water channel, 134-Third mounting hole, 140-Metering valve, 150-Pressure stabilizing chamber, 151-Fourth mounting hole, 152-Sealing ring, 160-Return connector, 170-Signal connector, 180-Water inlet connector;

[0027] 200-nozzle, 210-first elastic part, 220-second elastic part, 230-baffle, 240-stepped shaft, 250-retaining ring, 260-locking nut, 270-conical nozzle;

[0028] 300 - Piezoelectric ceramic ring, 310 - Electrode sheet;

[0029] 400 - Cooling channel, 410 - First connecting channel, 420 - Second connecting channel, 430 - Return hole;

[0030] 500 - Mounting base, 510 - Through hole;

[0031] 600 - Mounting flange. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] In the description of this utility model, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top surface", "bottom surface", "inner", "outer", "inner side", "outer side", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0034] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If the terms "first," "second," and "third" are used in the description, they are for descriptive purposes and to distinguish technical features, and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0035] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. The embodiments of this utility model will now be described based on its overall structure.

[0036] like Figures 1 to 3 As shown, the ultrasonic urea injection device in this embodiment includes: a housing 100, a cover 101, a box 102, an inner cavity 110, a first mounting hole 111, a second mounting hole 112, a limiting groove 113, a liquid inlet channel 120, a boss 130, a main water channel 131, a first branch water channel 132, a second branch water channel 133, a third mounting hole 134, a metering valve 140, a pressure stabilizing chamber 150, a fourth mounting hole 151, a sealing ring 152, and a return flow connection. Head 160, signal connector 170, water inlet connector 180, nozzle 200, first elastic part 210, second elastic part 220, baffle 230, stepped shaft 240, retaining ring 250, locking nut 260, conical nozzle 270, piezoelectric ceramic ring 300, electrode plate 310, cooling channel 400, first connecting channel 410, second connecting channel 420, return hole 430, mounting base 500, through hole 510, mounting flange 600.

[0037] The housing 100 is assembled from a cover 101 and a box 102. An inner cavity 110 and a cooling channel 400 are formed within the box 102. A mounting base 500 is provided at the bottom of the housing 100, and a mounting flange 600 is provided on the outer periphery of the mounting base 500. A through hole 510 is formed within the mounting base 500. The opening of the inner cavity 110 is located at the top of the housing 100. A second mounting hole 112 is located at the bottom of the inner cavity 110, and the lower end of the second mounting hole 112 communicates with the top end of the through hole 510. The diameter of the second mounting hole 112 is larger than the diameter of the through hole 510. The cooling channel 400 is positioned relative to the first... The two mounting holes 112 are positioned correspondingly and surround the outside of the second mounting hole 112 to form a C-shaped layout; a first connecting channel 410 and a second connecting channel 420 are also provided in the wall of the housing 102. The axes of the first connecting channel 410 and the second connecting channel 420 are parallel to the axis of the inner cavity 110. One end of the first connecting channel 410 is connected to one end of the cooling channel 400, and one end of the second connecting channel 420 is connected to the other end of the cooling channel 400. The other ends of the first connecting channel 410 and the other ends of the second connecting channel 420 extend outward from the top of the housing 100.

[0038] It is worth noting that the cooling channel 400, the first connecting channel 410 and the second connecting channel 420 can be machined on the housing 100 by drilling. The vertically intersecting holes form a C-shaped cooling channel 400, which is then sealed at the opening using water plugs or screw plugs in conjunction with anaerobic adhesive. Alternatively, the cooling channel 400, the first connecting channel 410 and the second connecting channel 420 can be directly cast by casting.

[0039] The cover 101 is bolted to the top of the housing 100. A first mounting hole 111 is formed at the bottom of the cover 101, and the axes of the first mounting hole 111 and the second mounting hole 112 coincide. A liquid inlet channel 120 is formed on the side of the cover 101 and intersects perpendicularly with the first mounting hole 111. A boss 130 is provided on the top of the cover 101. The main water channel 131, the first branch water channel 132, and the second branch water channel 133 are all located within the boss 130. The main water channel 131... The axis of the second water channel 133 is parallel to the axis of the first mounting hole 111, and the axis of the first water channel 132 is perpendicular to the axis of the main water channel 131. A third mounting hole 134 is provided on the side of the boss 130, and the third mounting hole 134 communicates with the first water channel 132. The other end of the first connecting channel 410 communicates with the second water channel 133. The water inlet connector 180 is installed at the opening of the main water channel 131. A return hole 430 is also provided on the cover 101. One end of the flow hole 430 is connected to the other end of the second connecting channel 420, and the return connector 160 is installed at the other end of the return hole 430; a lead wire hole is also provided on the top of the housing 100, and a signal connector 170 is installed at the upper end of the lead wire hole. The signal wire of the signal connector 170 can be introduced from the lead wire hole to the bottom of the cover 101; the pressure stabilizing chamber 150 is detachably installed on the cover 101, and a flow hole is provided at the installation position of the pressure stabilizing chamber 150. The bottom of the pressure stabilizing chamber 150 is connected to the side of one end of the liquid inlet channel 120 through the flow hole. A fourth mounting hole 151 is provided on the side of the pressure stabilizing chamber 150. One end of the metering valve 140 is fixedly connected to the third mounting hole 134, and the other end of the metering valve 140 extends into the fourth mounting hole 151 and is fixedly connected to the pressure stabilizing chamber 150 through the sealing ring 152. The sealing ring 152 is sealed between the other end of the metering valve 140 and the fourth mounting hole 151 and is bonded with glue.

[0040] In addition, the limiting groove 113 is formed at the bottom of the cover 101. It is a cylindrical structure, and the first mounting hole 111 is located inside the limiting groove 113 and its axis coincides with the axis of the limiting groove 113.

[0041] The nozzle 200 has a cylindrical body. Its upper end is slidably inserted into the first mounting hole 111 and can slide along the axis of the first mounting hole 111. The lower end of the nozzle 200 passes through the through hole 510 and extends out from the bottom of the mounting base 500. The diameter of the lower end of the nozzle 200 gradually decreases to form a conical structure. A conical nozzle 270 is provided at the lower end of the nozzle 200. A baffle 230 is provided in the middle of the nozzle body. The edge of the baffle 230 has a circular outline, and the bottom of the baffle 230 is provided with... A cylindrical stepped shaft 240 is provided, the diameter of which matches the diameter of the second mounting hole 112 and is smaller than the diameter of the baffle 230. The stepped shaft 240 is slidably inserted into the second mounting hole 112. The first elastic part 210 and the second elastic part 220 are annular structures. The first elastic part 210 is fitted on the outer side of the upper end of the nozzle 200 and is engaged in the limiting groove 113. The second elastic part 220 is fitted on the outer periphery of the stepped shaft 240. The second elastic part 220 can simultaneously engage with the bottom of the baffle 230 and the inner cavity 110. The bottom of the nozzle 200 is abutted and elastically compressed; several piezoelectric ceramic rings 300 and electrode plates 310 are fitted onto the body of the nozzle 200 and stacked alternately. A retaining ring 250 and a locking nut 260 are also fitted onto the body of the nozzle 200. The piezoelectric ceramic rings 300 and electrode plates 310 are located between the retaining ring 250 and the baffle 230. The locking nut 260 is threadedly connected to the body of the nozzle 200. When tightened, it can press the retaining ring 250 against the outside of the baffle 230, thereby fixing the piezoelectric ceramic rings 300 and electrode plates 310. 310 is electrically connected to the signal line, and the top of the locking nut 260 abuts against the bottom of the first elastic part 210. When the cover 101 and the housing 102 are assembled together, the first elastic part 210 and the second elastic part 220 can be subjected to axial compressive force to produce elastic deformation, so that the sides of the two can seal the opening positions of the first mounting hole 111 and the second mounting hole 112, which can prevent the liquid in the liquid inlet channel 120 and the mist in the SCR from entering the inner cavity 110 and affecting the circuit at the electrode plate 310.

[0042] Next, the working principle of an ultrasonic urea injection device in this embodiment will be described in detail to enable those skilled in the art to better understand this utility model:

[0043] In use, the device is installed on the SCR housing via the mounting flange 600, allowing the conical nozzle 270 to extend into the SCR cavity. The inlet connector 180 is connected to the high-pressure pipeline of the urea pump, the metering valve 140 is connected to the controller, the return connector 160 is connected to the urea tank, and the signal connector 170 is connected to the ultrasonic generator. The ultrasonic generator is connected to the controller to form a control closed loop.

[0044] During operation, the urea pump delivers urea to the main water channel 131. The metering valve 140 closes first, and the urea flows through the second branch water channel 133 and the cooling channel 400. The ultrasonic generator is activated, causing the transducer assembly composed of piezoelectric ceramics and electrode plates 310 to vibrate the nozzle 200. Optimal atomization is achieved when the frequency of the ultrasonic generator matches the natural frequency of the nozzle 200. At this point, the controller opens the metering valve 140, allowing urea to flow through the metering valve 140 into the pressure stabilizing chamber 150 and the inlet pipe. It is then ejected from the conical nozzle 270 through the nozzle 200. Because the ultrasonic waves break up the droplets, the resulting spray particle size reaches approximately 0.012 mm, far exceeding the atomization effect of existing urea nozzles. Simultaneously, the ultrasonic waves diffuse through the inlet pipe, breaking up and dislodging crystals within the pipe and nozzle 200, preventing crystallization. Meanwhile, the friction between the first mounting hole 111 and the upper side wall of the nozzle 200, and between the second mounting hole 112 and the side of the stepped shaft 240, generates heat during oscillation, thereby raising the temperature of the urea in the cooling channel 400. The heated urea flows back to the urea tank, further increasing the temperature of the urea in the urea tank. Under cold conditions, this can further improve the anti-crystallization effect of the urea in the entire urea injection system. When the ambient temperature changes, the flow rate in the cooling channel can be changed by regulating the flow rate through the urea pump and metering valve, thereby stabilizing the operating temperature of the entire device and further improving the stability of performance.

[0045] The atomization effect of this device is mainly related to the frequency generated by the ultrasonic generator. It can be compatible with urea pressure values ​​of 60~900kPa, making it more widely applicable and more compatible.

[0046] In summary, the ultrasonic urea injection device in this embodiment uses a nozzle 200 with a suspension structure and a transducer consisting of a piezoelectric ceramic ring 300 and an electrode plate 310 installed on the nozzle 200 to generate ultrasonic waves through oscillation. This breaks down and refines liquid particles, reducing particle size and improving atomization. Furthermore, the atomization effect is controlled by the ultrasonic frequency and is not affected by the inlet pressure, thus having a wider range of applications. After entering the main water channel 131, the urea can be diverted into the inlet channel 120 and the cooling channel 400. When the nozzle 200 oscillates, it can not only break down crystals in the pipe but also generate heat through friction at the contact points. When the external temperature changes, the device can maintain a stable temperature by changing the liquid flow rate in the cooling channel 400, which can both alleviate crystallization and cool down the device to maintain stable performance.

[0047] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it is obvious that many changes and variations can be made based on the above teachings. Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art, after reading this specification, can make modifications, substitutions, variations, and various choices and changes to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, variations, and choices and changes are within the scope of the claims of the present invention and are protected by patent law.

Claims

1. An ultrasonic urea injection device, comprising: The housing has an inner cavity, with a liquid inlet channel at the top of the inner cavity. A nozzle is located within the inner cavity, one end of which communicates with the liquid inlet channel, and the other end of which extends outward from the bottom of the housing. Alternatingly stacked piezoelectric ceramic rings and electrode plates are fitted around the nozzle. The feature is that: The top and bottom of the inner cavity are respectively provided with a first mounting hole and a second mounting hole. The first mounting hole communicates with the liquid inlet channel. A cooling channel is provided around the outside of the second mounting hole. The housing is also provided with a main water channel. One end of the main water channel is provided with a water inlet connector. The other end of the main water channel is provided with a first branch water channel and a second branch water channel. A metering valve and a pressure stabilizing chamber are connected between the first branch water channel and the liquid inlet channel. The second branch water channel is connected to one end of the cooling channel. The other end of the cooling channel is provided with a return connector. The rod of the nozzle can be fitted into the first mounting hole and the second mounting hole and can slide along the axis of the nozzle. A first elastic part and a second elastic part are respectively provided between the nozzle and the top and bottom of the inner cavity. The first elastic part and the second elastic part can cause the nozzle to generate elastic vibration in the axial direction.

2. The ultrasonic urea injection device according to claim 1, characterized in that, A baffle is fixedly installed on the nozzle. The bottom of the baffle is provided with a stepped shaft. The stepped shaft is slidably fitted into the second mounting hole. The second elastic part is an annular structure and is fitted around the outer periphery of the stepped shaft. The second elastic part can simultaneously abut against the bottom of the baffle and the bottom of the inner cavity and be elastically compressed.

3. The ultrasonic urea injection device according to claim 2, characterized in that, A detachable retaining ring is fitted on the nozzle. The piezoelectric ceramic ring and the electrode plate are located between the retaining ring and the baffle. A locking nut is provided on the top of the retaining ring. The locking nut is threaded to the body of the nozzle. One end of the nozzle is slidably fitted into the first mounting hole. The first elastic part is an annular structure and is fitted around the outer periphery of one end of the nozzle. The first elastic part can simultaneously abut against the top of the locking nut and the top of the inner cavity and be elastically compressed.

4. The ultrasonic urea injection device according to claim 3, characterized in that, A recessed limiting groove is provided at the top of the inner cavity, the first mounting hole is opened in the limiting groove, and the outer periphery of the first elastic part can be locked in the limiting groove.

5. The ultrasonic urea injection device according to claim 4, characterized in that, The housing is assembled from a cover and a box. The inner cavity and the cooling channel are formed in the box. The liquid inlet channel, the main water channel, the first branch water channel and the second branch water channel are formed on the cover. The cover and the box are assembled by bolts.

6. The ultrasonic urea injection device according to claim 5, characterized in that, The housing is provided with a first connecting channel and a second connecting channel. The axes of the first connecting channel and the second connecting channel are parallel to the axis of the inner cavity. One end of the first connecting channel is connected to one end of the cooling channel, and one end of the second connecting channel is connected to the other end of the cooling channel. The cover is provided with a reflux hole. One end of the reflux hole is connected to the other end of the second connecting channel. The reflux connector is installed at the other end of the reflux hole. The other end of the first connecting channel is connected to the second water distribution channel.

7. The ultrasonic urea injection device according to claim 6, characterized in that, The top of the cover is provided with a boss, and the main water channel, the first branch water channel, and the second branch water channel are all located in the boss. The side of the boss is provided with a third mounting hole, which is connected to the first branch water channel.

8. The ultrasonic urea injection device according to claim 7, characterized in that, The pressure stabilizing chamber is detachably installed on the cover. The bottom of the pressure stabilizing chamber is connected to one end of the liquid inlet channel. A fourth mounting hole is provided on the side of the pressure stabilizing chamber. One end of the metering valve is fixedly connected to the third mounting hole, and the other end of the metering valve is fixedly connected to the fourth mounting hole.

9. The ultrasonic urea injection device according to claim 8, characterized in that, A sealing ring is provided between the other end of the metering valve and the fourth mounting hole.

10. The ultrasonic urea injection device according to claim 1, characterized in that, The top of the housing is provided with a signal connector, which is electrically connected to the electrode plate; the bottom of the housing is provided with a mounting base, the outer periphery of the mounting base is provided with a mounting flange, the mounting base is provided with a through hole, the other end of the nozzle passes through the through hole and extends out from the bottom of the mounting base, the diameter of the other end of the nozzle gradually decreases and is provided with a conical nozzle.

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