Ultrasonic tail gas after-treatment system

Abstract

The invention relates to the technical field of tail gas treatment, and particularly discloses an ultrasonic tail gas aftertreatment system which comprises a urea storage unit, a urea pump unit, a control unit, a catalyst unit, a urea injection unit, a metering valve, an ultrasonic signal generator, a liquid inlet pipeline and a backflow pipeline. The urea spraying unit comprises a fixing part, an energy conversion part, a spraying pipe part and a cooling water channel, the spraying pipe part generates vibration through the energy conversion part to generate ultrasonic waves, the effect of refining the spraying granularity can be achieved, and urea crystals in a pipeline can be eliminated through the water hammer effect; the liquid inlet pipeline is divided into a first branch used for liquid inlet and a second branch used for cooling, the second branch is connected with the cooling water channel, and a backflow pipeline is connected between the cooling water channel and the urea storage unit. The flow in the cooling water channel can be automatically distributed and regulated through the urea pump unit and the metering valve according to the environment temperature, so that the urea spraying unit is controlled to be at the optimal working temperature all the time, and the working state is more stable.

Description

Technical Field

[0001] The present invention belongs to the technical field of exhaust gas post-treatment, and particularly relates to an ultrasonic exhaust gas post-treatment system. Background Art

[0002] With the continuous upgrading of national emission standards, the traditional SCR (Selective Catalytic Reduction) exhaust gas post-treatment system has gradually been unable to meet the strict emission requirements, and a urea atomization injection system with a larger urea supply, better atomization performance, and high conversion efficiency is required to match it. Moreover, the urea nozzles in the traditional spray form will form crystals due to factors such as narrow pipelines, insufficient pressure, and low temperature during use, which will block the nozzles, affecting the service life and the normal operation of the entire exhaust gas post-treatment system.

[0003] In the patent document with the application number "CN201610467853.5", a urea liquid ultrasonic atomization device in a diesel engine SCR system is disclosed, including: an ultrasonic atomization nozzle; a pumping member, a pumping pipeline is arranged between the pumping member and the ultrasonic atomization nozzle; a switching member, the switching member is arranged in the pumping pipeline; an ultrasonic controller, the ultrasonic controller is respectively connected to the pumping member and the switching member for control, so that after the ultrasonic controller receives a urea mixing instruction, the ultrasonic controller controls the switching member to open the pumping pipeline between the pumping member and the ultrasonic atomization nozzle, and drives the pumping member to work to pump the urea in the urea tank to the ultrasonic atomization nozzle through the pumping pipeline. The atomization device in the comparative document can achieve finer atomization particle size through the ultrasonic nozzle, improve the urea atomization effect, improve the reduction efficiency of NOx in automobile exhaust gas, make the SCR catalytic converter not easily blocked, and extend the service life of the catalytic converter. However, it still cannot solve the influence on the solenoid valve and the ultrasonic nozzle in low-temperature and high-temperature environments, nor can it reflux or empty the residual urea in the ultrasonic nozzle, and still has a greater risk of crystallization.

[0004] The disclosure of the above background art content is only used to assist in understanding the inventive concept and technical solution of the present invention, and it does not necessarily belong to the prior art of this patent application. Without clear evidence indicating that the above content was publicly available on the filing date of this patent application, the above background art should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] The purpose of the present invention is to provide an ultrasonic exhaust gas post-treatment system, so as to overcome the defects of poor spray effect of the existing exhaust gas post-treatment system and easy crystallization at the urea nozzle.

[0006] To achieve the above object, the present invention provides an ultrasonic tail gas after-treatment system, which includes a urea storage unit, a urea pump unit, a control unit, a catalytic converter unit, and a urea injection unit; the urea injection unit includes a fixing part, a transducer part, and a nozzle part. The fixing part is fixedly connected to the catalytic converter unit. The nozzle part is floatingly connected to the fixing part and one end of it extends into the catalytic converter unit. The transducer part is fixedly connected to the nozzle part. A cooling water channel is provided in the fixing part. It also includes a metering valve, an ultrasonic signal generator, a liquid inlet pipeline, and a return pipeline. The control end of the ultrasonic signal generator is electrically connected to the control unit. The signal output end of the ultrasonic signal generator is electrically connected to the transducer part. The control end of the metering valve is electrically connected to the urea pump unit or the control unit. One end of the liquid inlet pipeline is connected to the injection interface of the urea pump unit. The other end of the liquid inlet pipeline is divided into a first branch pipeline and a second branch pipeline. The first branch pipeline is connected to the liquid inlet of the metering valve. The liquid outlet of the metering valve is communicated with the other end of the nozzle part. The second branch pipeline is communicated with one end of the cooling water channel. The other end of the cooling water channel is connected to the top of the urea storage unit by a return pipeline.

[0007] Preferably, in the above technical solution, an inner cavity is provided in the fixing part. An inlet liquid cavity and a guiding hole are respectively provided at the top and bottom of the inner cavity. The other end and the middle part of the nozzle part are respectively sleeved in the inlet liquid cavity and the guiding hole in a slidable manner. An elastic member is connected between the nozzle part and the inner cavity so that the injection part can be in an elastic floating state. The position of the cooling water channel corresponds to the position of the guiding hole and is arranged around the guiding hole.

[0008] Preferably, in the above technical solution, the axes of the inlet liquid cavity and the guiding hole coincide.

[0009] Preferably, in the above technical solution, a retaining ring is provided in the middle part of the nozzle part. A guiding ring is provided below the retaining ring. The diameter of the retaining ring is larger than that of the guiding ring. The diameter of the guiding ring is larger than that of the nozzle part. The guiding ring is slidably installed in the guiding hole.

[0010] Preferably, in the above technical solution, the transducer part includes a piezoelectric ceramic ring and an electrode plate. The piezoelectric ceramic ring and the electrode plate are sleeved on the nozzle part and alternately stacked. A detachable pressing plate is also sleeved on the nozzle part. The piezoelectric ceramic ring and the electrode plate are located between the pressing plate and the retaining ring. The electrode plate is electrically connected to the signal output end of the ultrasonic signal generator.

[0011] Preferably, in the above technical solution, the elastic members are respectively installed between the retaining ring and the bottom of the inner cavity and between the pressing plate and the top of the inner cavity.

[0012] Preferably, in the above technical solution, the diameter of the middle part of the nozzle part gradually decreases to one end thereof, and a conical nozzle is provided.

[0013] Preferably, in the above technical solution, a first temperature sensor and a flow sensor are provided in the return pipeline, and the first temperature sensor and the flow sensor are electrically connected to the control unit.

[0014] Preferably, in the above technical solution, an engine unit is further included. A heat exchange pipe is provided in the urea storage unit. The heat exchange pipe has a water inlet end and a water outlet end, and the water inlet end and the water outlet end are communicated with the water channel of the engine unit.

[0015] Preferably, in the above technical solution, the ultrasonic signal generator is provided with an independent power supply.

[0016] Compared with the existing technology, the present invention has the following beneficial effects:

[0017] 1. In the urea injection unit of the ultrasonic exhaust gas aftertreatment system of the present invention, the nozzle part generates ultrasonic waves through the vibration generated by the transducer part, which can not only play a role in refining the spray particle size but also eliminate the urea crystallization in the pipeline by using the water hammer effect. The cooling water channel can dissipate heat from the urea injection unit; and the liquid inlet pipeline is divided into a first branch for liquid inlet and a second branch for cooling. The second branch is connected to the cooling water channel, and a return pipeline is connected between the cooling water channel and the urea storage unit. The urea pump unit and the metering valve can automatically distribute and regulate the flow rate in the cooling water channel according to the ambient temperature, so as to control the urea injection unit to always be at the optimal working temperature, making the working state more stable.

[0018] 2. The liquid inlet cavity in the present invention can not only play a role in limiting and guiding the other end of the nozzle part, but also the relatively wide cavity can play a role in stabilizing the pressure and buffering the pressure, and can be compatible with a pressure range of 60 - 900 kPa, which is wider than the urea pressure compatibility range of traditional nozzles. Moreover, the atomization effect is determined by the vibration frequency of the nozzle part and is less affected by the liquid inlet pressure; at the same time, the liquid in the liquid inlet cavity can also cool the friction part between the outer side of the other end of the nozzle part and the inner wall of the liquid inlet cavity, playing a role in heat dissipation.

[0019] 3. The pressing plate and the retaining ring in the present invention can not only play a role in fixing the piezoelectric ceramic and the electrode sheet, but also play a role in connecting and limiting with the elastic part.

[0020] 4. A first temperature sensor and a flow sensor are installed in the return pipeline of the present invention, which can monitor the water temperature and flow rate in the cooling pipeline in real time, so as to actively feedback the flow control operation of the urea pump unit and the metering valve, in order to achieve precise regulation of the working temperature of the urea injection unit.

[0021] 5. The ultrasonic generator in the present invention can either use an independent power supply or share the power supply with the main system, making the operation of the urea injection unit more stable to prevent it from being affected by the ambient temperature. The independent power supply can avoid the influence of the voltage fluctuation of the main system.

[0022] 6. In the present invention, the first branch pipeline for liquid spraying and the second branch pipeline for cooling are connected to the urea pump unit through the same liquid inlet pipeline, and the reflux pipeline is connected to the top of the urea storage unit. When the entire system is shut down, the two pipelines can be back-pumped and emptied through the urea pump unit, thereby effectively preventing the crystallization of urea in each pipeline. Description of the Drawings

[0023] Figure 1 It is a structural diagram of the ultrasonic exhaust gas after-treatment system of the present invention.

[0024] Figure 2 It is a structural diagram of the urea injection unit.

[0025] Description of the Main Reference Numerals:

[0026] 100 - urea storage unit, 110 - engine unit, 120 - heat exchange tube;

[0027] 200 - urea pump unit, 210 - injection interface, 220 - liquid inlet interface, 230 - liquid return interface, 240 - liquid supply pipeline, 250 - liquid return pipeline;

[0028] 300 - control unit;

[0029] 400 - catalytic converter unit, 410 - second temperature sensor, 420 - third temperature sensor, 430 - NOx sensor;

[0030] 500 - urea injection unit, 510 - fixing part, 511 - inner cavity, 512 - liquid inlet cavity, 513 - guiding hole, 514 - elastic part, 520 - transducer part, 521 - piezoelectric ceramic ring, 522 - electrode plate, 523 - pressing plate, 530 - nozzle part, 531 - retaining ring, 532 - guiding ring, 533 - conical nozzle, 540 - cooling water channel;

[0031] 600 - metering valve;

[0032] 700 - ultrasonic signal generator;

[0033] 800 - liquid inlet pipeline, 810 - first branch pipeline, 820 - second branch pipeline;

[0034] 900 - reflux pipeline, 910 - first temperature sensor, 920 - flow sensor. Detailed Embodiments

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top part", "bottom part", "top surface", "bottom surface", "inner", "outer", "inner side", "outer side", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0037] In the description of the present invention, the meaning of "a number of" is one or more, the meaning of "a plurality of" is two or more, and understandings such as "greater than", "less than", "exceeding", etc. do not include the recited number, and understandings such as "above", "below", "within", etc. include the recited number. If terms such as "first", "second", "third" are described only for the purpose of description and for distinguishing technical features, they should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", "set" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. The embodiments of the present invention will be described below according to the overall structure of the present invention.

[0039] As Figure 1As shown in the figure, the ultrasonic tail gas post-treatment system in this embodiment includes: a urea storage unit 100, an engine unit 110, a heat exchange tube 120, a urea pump unit 200, an injection interface 210, a liquid inlet interface 220, a liquid return interface 230, a liquid supply pipeline 240, a liquid return pipeline 250, a control unit 300, a catalytic converter unit 400, a urea injection unit 500, a metering valve 600, an ultrasonic signal generator 700, a liquid inlet pipeline 800, a first branch pipeline 810, a second branch pipeline 820, a reflux pipeline 900, a first temperature sensor 910, and a flow sensor 920.

[0040] The urea pump unit 200 is provided with an injection interface 210, a liquid inlet interface 220, and a liquid return interface 230. The liquid inlet interface 220 is connected to the lower side of the urea storage unit 100 through the liquid supply pipeline 240, and the liquid return interface 230 is connected to the top of the urea storage unit 100 through the liquid return pipeline 250; a heat exchange tube 120 is installed in the urea storage unit 100, and the heat exchange tube 120 is provided with a water inlet end and a water outlet end, and the water inlet end and the water outlet end are communicated with the water channel of the engine unit 110.

[0041] The urea injection unit 500 includes a fixing part 510, a transducer part 520, and a nozzle part 530. The fixing part 510 is fixedly connected to the catalytic converter unit 400. The nozzle part 530 is floatingly connected to the fixing part 510 and one end thereof extends into the catalytic converter unit 400. The transducer part 520 is fixedly connected to the nozzle part 530. A cooling water channel 540 is arranged in the fixing part 510; one end of the liquid inlet pipeline 800 is connected to the injection interface 210 of the urea pump unit 200, and the other end of the liquid inlet pipeline 800 is divided into a first branch pipeline 810 and a second branch pipeline 820. The first branch pipeline 810 is connected to the liquid inlet of the metering valve 600. The liquid outlet of the metering valve 600 is connected to the top of the fixing part 510 and is communicated with the other end of the nozzle part 530. The second branch pipeline 820 is communicated with one end of the cooling water channel 540. The other end of the cooling water channel 540 is connected to the top of the urea storage unit 100 through the reflux pipeline 900. A first temperature sensor 910 and a flow sensor 920 are installed in the reflux pipeline 900; a second temperature sensor 410 for measuring the intake air temperature, a third temperature sensor 420 for measuring the exhaust gas temperature, and a NOx sensor 430 for measuring the NOx value are installed in the catalytic converter unit 400.

[0042] More specifically, the structure of the urea injection unit 500 is as Figure 2As shown in the figure, a cylindrical inner cavity 511 is provided in the fixing part 510. An inlet liquid cavity 512 and a guiding hole 513 are respectively opened at the top and bottom of the inner cavity 511. The inlet liquid cavity 512 is a cylindrical cavity and coincides with the axis of the guiding hole 513; a cylindrical retaining ring 531 is provided in the middle of the nozzle part 530. A cylindrical guiding ring 532 is arranged below the retaining ring 531. The diameter of the retaining ring 531 is larger than that of the guiding ring 532 but smaller than the diameter of the inner cavity 511. The diameter of the guiding ring 532 is larger than the diameter of the nozzle part 530. The guiding ring 532 is sleeved and inserted in the guiding hole 513 in a slidable manner. The upper end of the nozzle part 530 is sleeved and inserted in the inlet liquid cavity 512 in a slidable manner. Sealing components can be installed on the outer periphery of the upper end of the nozzle part 530, the outer periphery of the guiding ring 532, the mouth of the guiding hole 513 and the mouth of the inlet liquid cavity 512 to prevent urea from entering the inner cavity 511; the transducer part 520 includes a piezoelectric ceramic ring 521 and an electrode sheet 522. The piezoelectric ceramic ring 521 and the electrode sheet 522 are sleeved on the middle of the nozzle part 530 and stacked alternately. A detachable pressing plate 523 is also sleeved on the nozzle part 530. The piezoelectric ceramic ring 521 and the electrode sheet 522 are located between the pressing plate 523 and the retaining ring 531. The electrode sheet 522 is electrically connected to the signal output end of the ultrasonic signal generator 700. The pressing plate 523 can be fixedly connected to the nozzle part 530 by means of threads, screws or pins, etc.; elastic members 514 are respectively installed between the retaining ring 531 and the bottom of the inner cavity 511 and between the pressing plate 523 and the top of the inner cavity 511 to enable the nozzle part 530 to achieve axial elastic floating. The elastic members 514 can adopt spring members in the structural forms such as cylindrical springs, rubber springs or plate springs, etc.; the outer diameter of the nozzle part 530 gradually decreases from the bottom position of the guiding ring 532 to its lower end and is provided with a conical nozzle 533 to form a horn-shaped structure; the cooling water channel 540 is in a ring structure, and its position corresponds to the position of the guiding hole 513 and is arranged around the guiding hole 513.

[0043] In addition, the ultrasonic signal generator 700 is also provided with an independent power supply and a power supply system; the control end of the ultrasonic signal generator 700, the control end of the urea pump unit 200, the first temperature sensor 910, the flow sensor 920, the second temperature sensor 410, the third temperature sensor 420 and the NOx sensor 430 are all electrically connected to the control unit 300; the control end of the metering valve 600 is electrically connected to the urea pump unit 200 or the control unit 300, which mainly depends on the function of the urea pump unit 200.

[0044] Next, the working principle of an ultrasonic exhaust gas aftertreatment system in this embodiment will be described in detail so that those skilled in the art can better understand the present invention:

[0045] During spraying, first, the controller issues an instruction to close the metering valve 600. Then, the urea pump unit 200 pumps urea into the liquid inlet pipeline 800. The urea first flows through the second branch and enters the cooling water channel 540, and then returns to the urea storage unit 100 through the return pipeline 900 to form a cooling loop. Then, the controller controls the ultrasonic signal generator 700 to start, enabling the transducer part 520 to work, driving the nozzle part 530 to vibrate. At the same time, the controller controls the metering valve 600 to open, allowing the urea to flow through the first branch pipeline 810, the liquid inlet cavity 512, and the nozzle part 530 in sequence. Using ultrasonic interference, a tension wave is formed at the liquid-gas interface. The standing wave can tear the urea droplets, and finally, urea aerosol with a diameter of about 0.01 mm is sprayed into the catalytic converter unit 400, which has a significant improvement compared to the particle size of only 0.05 - 0.15 mm of traditional urea nozzles. And when the nozzle part 530 vibrates, the urea crystals on its pipe wall can be shaken off, and at the same time, a water hammer effect is formed at the connection end of the liquid inlet cavity 512 and the first branch pipeline 810 to knock down the urea crystals on its wall, effectively preventing the sticking of urea crystals. At the same time, due to the vibration of the nozzle part 530, heat can also be generated at the liquid inlet cavity 512 and the guiding hole 513, so that the urea injection unit 500 can maintain a certain working temperature when working in a relatively cold ambient temperature, reducing the crystallization rate of urea. When the ambient temperature is overheated, the liquid flow rate in the second branch pipeline 820 can be increased through the joint regulation of the urea pump unit 200 and the metering valve 600, so as to improve the cooling effect and prevent the urea injection unit 500 from overheating, thus ensuring the stability of the work.

[0046] When closed, the urea pump unit 200 can suck back the liquid inlet pipeline 800. At this time, the urea in the cooling water channel 540, the return pipeline 900, the nozzle part 530, and the liquid inlet cavity 512 can all be sucked back and emptied, thus preventing the crystallization of urea in a static state during long-term non-use, playing a protective role.

[0047] Since the atomization effect is determined by the frequency of the ultrasonic signal generator 700, when the frequency generated by the ultrasonic signal generator 700 is consistent with the natural frequency of the nozzle part 530, it can achieve the best atomization effect, and is less affected by the inlet liquid pressure and flow rate, so it can adapt to a pressure value of 60 - 900 kPa, with a wider urea pressure compatibility range and stronger versatility.

[0048] The ultrasonic signal generator 700 is driven by an independent power supply device and power source, and is less affected by other electrical equipment, avoiding the instability caused by sharing the power supply.

[0049] In summary, in the urea injection unit 500 of the ultrasonic exhaust gas post-treatment system in this embodiment, the nozzle part 530 in the urea injection unit 500 generates ultrasonic waves through the vibration of the transducer part 520, which can not only refine the spray particle size but also utilize the water hammer effect to eliminate urea crystallization in the pipeline. The cooling water channel 540 can dissipate heat from the urea injection unit 500; and the liquid inlet pipeline 800 is divided into a first branch for liquid inlet and a second branch for cooling, the second branch is connected to the cooling water channel 540, and a return pipeline 900 is connected between the cooling water channel 540 and the urea storage unit 100. Through the urea pump unit 200 and the metering valve 600, the flow rate in the cooling water channel 540 can be automatically distributed and regulated according to the ambient temperature, so as to control the urea injection unit 500 to always be at the optimal working temperature, making the working state more stable.

[0050] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the present invention to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teachings. Although embodiments of the present invention have been shown and described, the specific embodiments are merely interpretations of the present invention and not limitations thereof. The specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical applications, so that those skilled in the art can, after reading this specification, make modifications, substitutions, variations, and various different selections and changes that do not make creative contributions to the embodiments as needed, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. An ultrasonic exhaust gas post-treatment system, comprising a urea storage unit, a urea pump unit, a control unit, a catalytic converter unit and a urea injection unit; characterized in that: The urea injection unit includes a fixed part, a transducer part and a nozzle part. The fixed part is fixedly connected to the catalytic converter unit. The nozzle part is floatingly connected to the fixed part and one end of it extends into the catalytic converter unit. The transducer part is fixedly connected to the nozzle part. A cooling water channel is provided in the fixed part; It further includes a metering valve, an ultrasonic signal generator, a liquid inlet pipeline and a return pipeline. The control end of the ultrasonic signal generator is electrically connected to the control unit. The signal output end of the ultrasonic signal generator is electrically connected to the transducer part. The control end of the metering valve is electrically connected to the urea pump unit or the control unit. One end of the liquid inlet pipeline is connected to the injection interface of the urea pump unit. The other end of the liquid inlet pipeline is divided into a first branch pipeline and a second branch pipeline. The first branch pipeline is connected to the liquid inlet of the metering valve. The liquid outlet of the metering valve is communicated with the other end of the nozzle part. The second branch pipeline is communicated with one end of the cooling water channel. The other end of the cooling water channel is connected to the top of the urea storage unit by a return pipeline.

2. The ultrasonic tail gas post-treatment system according to claim 1, wherein An inner cavity is provided in the fixed part. A liquid inlet cavity and a guiding hole are respectively provided at the top and bottom of the inner cavity. The other end and the middle part of the nozzle part are respectively sleeved in the liquid inlet cavity and the guiding hole in a slidable manner. An elastic member is connected between the nozzle part and the inner cavity to enable the injection part to be in an elastic floating state. The position of the cooling water channel corresponds to the position of the guiding hole and is arranged around the guiding hole.

3. The ultrasonic tail gas post-treatment system according to claim 2, wherein, The axes of the liquid inlet cavity and the guiding hole coincide.

4. The ultrasonic tail gas post-treatment system according to claim 2, characterized in that, A retaining ring is provided in the middle of the nozzle part. A guiding ring is provided below the retaining ring. The diameter of the retaining ring is larger than that of the guiding ring. The diameter of the guiding ring is larger than that of the nozzle part. The guiding ring is slidably installed in the guiding hole.

5. The ultrasonic tail gas post-treatment system according to claim 4, characterized in that The transducer part includes a piezoelectric ceramic ring and an electrode plate. The piezoelectric ceramic ring and the electrode plate are sleeved on the nozzle part and stacked alternately. A detachable pressing plate is also sleeved on the nozzle part. The piezoelectric ceramic ring and the electrode plate are located between the pressing plate and the retaining ring. The electrode plate is electrically connected to the signal output end of the ultrasonic signal generator.

6. The ultrasonic tail gas post-treatment system according to claim 5, characterized in that, The elastic members are respectively installed between the retaining ring and the bottom of the inner cavity and between the pressing plate and the top of the inner cavity.

7. The ultrasonic tail gas post-treatment system according to claim 1, wherein The diameter of the middle part of the nozzle part gradually decreases to its one end and is provided with a conical nozzle.

8. The ultrasonic tail gas post-treatment system according to claim 1, wherein A first temperature sensor and a flow sensor are provided in the return pipeline. The first temperature sensor and the flow sensor are electrically connected to the control unit.

9. The ultrasonic tail gas post-treatment system according to claim 1, wherein, It further includes an engine unit. A heat exchange tube is provided in the urea storage unit. The heat exchange tube is provided with a water inlet end and a water outlet end. The water inlet end and the water outlet end are communicated with the water channel of the engine unit.

10. The ultrasonic tail gas post-treatment system according to claim 1, wherein, The ultrasonic signal generator is provided with an independent power supply.

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