A urea liquid supply module for preventing liquid from freezing and damage

Abstract

A urea liquid supply module for preventing liquid from being damaged by freezing comprises a module body, a urea supply pump, a urea liquid level sensor, a urea liquid temperature sensor, a heating and thawing circulating water pipe, a water inlet nozzle and a water outlet nozzle. A circulating water flow channel is arranged inside the module body, and the heating and thawing circulating water pipe is connected with the heating and thawing circulating water pipe inlet and outlet water nozzles through the circulating water flow channel. The urea liquid supply module is characterized in that more than one gas space is arranged on the circulating water flow channel, and one of the gas spaces is arranged on the urea supply pump. When the circulating water or the working liquid freezes and expands in volume, the gas in the gas space is compressed and releases the volume, thereby preventing the components from being damaged when the liquid freezes.

Description

Technical Field

[0001] The invention belongs to the field of engine emission control, and in particular relates to a urea liquid supply metering system of engine exhaust selective reduction (SCR) technology. Background Art

[0002] As environmental issues become increasingly prominent, energy conservation and emission reduction have become an endless requirement for vehicles and engines. To this end, countries have introduced a series of vehicle emission standards, which are becoming increasingly stringent. In response, vehicles powered by internal combustion engines need to install emission post-treatment systems in order to meet emission requirements. For example, SCR (Selective Catalytic Reduction) technology, which is currently mainly used for catalytic treatment of pollutants such as NOx in diesel engine exhaust, has become a necessary technology for diesel vehicles.

[0003] SCR technology requires that the NOx reduction agent be quantitatively injected into the diesel engine exhaust. The reducing agent includes a 32.5% weight concentration of urea aqueous solution (also called diesel exhaust treatment fluid DEF=Diesel Exhaust Fluid, or AdBlue), or ammonia. During the SCR exhaust catalytic treatment process, the DEF treatment fluid is quantitatively injected into the diesel engine exhaust, decomposed into ammonia through the high temperature of the exhaust, and mixed with the exhaust gas into the SCR catalytic converter. Under the action of the catalyst, the ammonia will react with the NOx in the engine exhaust to decompose NOx into harmless N2 and H2O. If the amount of DEF injection does not match the NOx content in the exhaust or the quality of the urea solution does not meet the requirements, then either the NOx cannot be fully reduced and decomposed, the emission will increase, or a lot of remaining ammonia will be discharged into the atmosphere, causing secondary pollution.

[0004] However, the quality of urea aqueous solution, an important reactant, is often only controlled at the factory or during inspection, and most post-treatment systems are not equipped with a device that can detect the quality of urea solution. At present, many vehicle users use inferior urea solution or add water solvent to urea solution to reduce the cost of use, resulting in uneven quality of urea solution, which seriously affects the treatment effect of exhaust NOx and makes SCR useless. Therefore, it is very necessary to set up a sensor that can detect the quality of urea in the device.

[0005] In addition, due to the characteristics of the urea aqueous solution itself, after the injection is completed, the urea mixture remaining in the closed urea system and pipeline may freeze at a temperature below the freezing point of the urea solution (-11~12℃), which will not only cause the urea injection to be interrupted, but also damage the urea injection system due to the expansion of the urea solution volume when it freezes. Most of the existing SCR technologies consider adding auxiliary heating devices to ensure the normal operation of the system. However, the existing device that provides the injection power source is too large or other reasons make it difficult to integrate the system components into the DEF storage tank, and it is often necessary to design a complex ice melting device, which makes the system larger and more difficult to arrange. At the same time, the more complex the system, the higher the cost in this regard. In particular, for the injection system with a built-in urea pump, the urea pump is often arranged close to the bottom of the box, and it has no thawing ability itself. The system needs to be completely thawed before it can start working, resulting in the system being limited in both thawing time and layout space. For example, U.S. Patent US20090301067A1 discloses a metering injection device and method thereof. The metering injection device is a solenoid-driven plunger pump nozzle installed on the exhaust pipe. It needs an external low-pressure pump to provide working fluid from the DEF tank. It cannot work properly without the assistance of special ice melting and nozzle cooling devices. In addition, the operation, system and method of SCR metering injection disclosed in US Patent US8356471B2 provide a scheme for separate control of the pump and nozzle ends. In addition to strict requirements on the temperature control of the device and the deicing of the pipeline, its metering accuracy also needs to be precisely controlled.

[0006] For the entire urea injection device, it is very necessary to leave a gas space on the top of the urea tank, which can not only ensure the normal exhaust of each actuator, but also ensure that the urea tank itself has enough expansion space when the urea solution freezes. However, it is difficult to make accurate judgments when adding urea. The existing structure often adds a pipeline connected to the atmosphere, but due to the system's ability to withstand dirt, a filtering device needs to be added, which further increases the complexity and cost of the system.

[0007] In summary, the research work on NOx selective catalytic reduction technology (SCR) is very valuable, whether it is the simplified structure and application method, or the accuracy and stability of its metering injection system. Summary of the invention

[0008] The present invention aims to solve the above problems and to provide a urea liquid supply module with simple structure, good adaptability, stable operation and low cost.

[0009] To achieve the above object, the present invention adopts the following technical scheme: a urea liquid supply module, comprising a urea supply pump, a metering nozzle, a module body, a urea liquid level sensor, a urea liquid temperature sensor, a urea liquid quality sensor, and a urea liquid heating and thawing circulating water pipe. A circulating water flow channel is arranged inside the module body, and the heating and thawing circulating water pipe is connected to the heating and thawing circulating water pipe inlet and outlet water nozzles through the circulating water flow channel.

[0010] The urea liquid supply module is provided with more than one gas space, one of which is provided on the circulating water flow channel, located at the water inlet or outlet of the heating and thawing circulating water pipe. The second gas space is provided on the urea supply pump, close to the liquid outlet. When the circulating water or working liquid freezes and expands in volume, the gas in the gas space is compressed and releases the volume, thereby preventing the components from being damaged when the liquid freezes. The total volume of the gas space is greater than or equal to the expansion volume of the liquid in the supply module when it freezes.

[0011] The gas space can be a bulging space with a certain height, which is connected to the circulating water channel at the bottom but is closed at the top. The downward connecting channel at the bottom is large enough so that the liquid entering the bulging space can rely on its own gravity and overcome the resistance of bubbles to return to the circulating water channel smoothly.

[0012] The gas space may also be a closed hollow volume made of a soft thin-walled material, which is compressed and releases volume when the surrounding pressure increases. The closed hollow volume is made of rubber material.

[0013] The module body is also provided with a urea liquid outlet nozzle, a liquid return nozzle, an internal liquid outlet channel and a liquid return channel, as well as the heating and thawing circulating water pipe inlet and outlet nozzles, and a mounting clip for fixing the module to the urea tank after the module is inserted into the urea tank from the upper part of the urea tank.

[0014] The liquid supply pump includes a liquid inlet and a liquid outlet. The liquid inlet is provided with a primary filter screen. The urea solution enters the supply pump after being filtered through the primary filter screen under the action of its own gravity. A vertical bubble exhaust pipe is provided on the primary filter screen. In addition, a horizontal bubble exhaust pipe is provided in the middle of the liquid supply pump. The two bubble exhaust pipes are connected by a three-way pipe and lead to the space above the bottom plane of the module mounting buckle. The three-way part is provided with a part of the primary filter screen, so that when the urea liquid is frozen and thawed, the urea supply pump can be fed with liquid through the first thawed part of the primary filter screen.

[0015] The urea pump outlet is connected to a liquid outlet pipe, which is a shaped pipe designed to be as close to the heating and thawing circulating water pipe as possible. The liquid outlet pipe extends into the module body and communicates with the internal liquid outlet channel and leads to the liquid outlet nozzle. A sealing gasket is installed between the liquid outlet pipe and the liquid outlet channel for sealing and shock absorption.

[0016] The metering nozzle includes a liquid inlet nozzle and a liquid return nozzle, the liquid inlet end is connected to the liquid outlet nozzle through a liquid supply pipe, the liquid return end is connected to the liquid return nozzle through a liquid return pipe, the other end of the liquid return nozzle is connected to a liquid return channel, and leads to a certain depth inside the urea tank through the liquid return channel.

[0017] The urea liquid supply pump and the urea liquid quality sensor are located at the bottom of the module and fixed on the urea liquid heating and thawing circulating water pipe in a manner that facilitates ice melting. The urea liquid level sensor and the urea liquid temperature sensor are fixed through the module and extend into the urea tank close to the urea supply pump.

[0018] The module body also includes a trapezoidal step in an axial array, and the mounting clip includes a limiting hole that matches the step of the module body and a through hole that allows the pipelines of the urea liquid supply module to pass through. The mounting clip is fixed to the module body by a clamping manner and limits the pipelines leading to the inside of the body and the sensor pipelines at the same time, ensuring the stability of each installation component.

[0019] The module body is also designed with a secondary urea liquid filter device, which is located upstream of the liquid outlet nozzle and includes a cavity with a threaded cover for replacing the internal filter element. The filtering accuracy is higher than that of the primary filter to ensure the normal operation of the downstream nozzle and improve the service life of the system.

[0020] Furthermore, the above-mentioned urea liquid supply module includes a pipeline residual urea liquid processing device, and an optional scheme of the pipeline urea liquid processing device is: a urea re-extraction device is arranged on the module body, including a re-extraction valve and a re-extraction pipeline. The re-extraction pipeline includes an ejection chamber, a drainage channel that leads to a certain depth of the urea tank, a liquid inlet and a liquid outlet. The re-extraction valve is a one-way valve opened by electromagnetic force, and the ejection chamber is a space that is conducive to the rapid outflow of urea liquid from the drainage channel when the re-extraction valve is opened. At the same time, the space is also conducive to the liquid in the liquid outlet channel entering the drainage channel. The urea re-extraction device is connected in series to the internal liquid outlet channel through the liquid inlet and the liquid outlet. In the normal spraying state, the urea liquid in the internal liquid outlet channel passes through the liquid inlet and the liquid outlet of the urea re-extraction device and directly reaches the liquid outlet nozzle and is then output. When the pipeline needs to be cleaned, the return valve is started, and the urea liquid enters the drainage channel through the liquid inlet at a certain speed, so that a certain vacuum degree is generated in the injection cavity, and most of the urea liquid in the liquid supply pipe and the return pipe can be drawn back to the urea tank.

[0021] Another optional solution for the pipeline residual urea liquid treatment device is: a urea cleaning device is arranged on the module body, including a diaphragm air pump and a cleaning pipeline, a one-way valve is arranged on the cleaning pipeline, and is one-way connected with the liquid outlet pipe. When necessary, the air pump is started to suck air from the urea tank and pressurize to open the one-way valve, so that most of the urea liquid in the liquid supply pipe and the liquid return pipe can be pumped back to the urea tank.

[0022] A further optimized design of the urea liquid supply module is that a urea tank atmospheric pipeline and a nozzle are provided on the module body. One end of the urea tank atmospheric pipeline is connected to the nozzle, and the other end extends into the urea tank to a certain depth, which is intended to prevent the urea tank from being overfilled when the urea tank filling port is higher than the module body, and to balance the air pressure in the urea tank.

[0023] In addition, the urea liquid heating and thawing circulating water pipe can be designed to be L-shaped at the bottom, which is convenient for fixing the urea pump and the urea liquid quality sensor at the same height position of the module, and can be inserted into the bottom of the urea tank through the module mounting hole of the urea tank.

[0024] The following technical solutions further limit or optimize the present invention.

[0025] The beneficial effects of the present invention are: when a straight-tube exhaust mixing pipe with a simple structure and convenient installation and arrangement is adopted, the risk of crystallization in the exhaust pipe of the engine is reduced, the uniformity of mixing of reactants and exhaust gas is improved, and the cost of the SCR system can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is one of the structural schematic diagrams of an embodiment of a urea liquid supply module for preventing liquid from freezing and damage provided by the present invention.

[0027] Figure 2 This is a second structural schematic diagram of an embodiment of a urea liquid supply module for preventing liquid from freezing and damage provided by the present invention.

[0028] Figure 3 This is a third structural schematic diagram of an embodiment of a urea liquid supply module for preventing liquid from freezing and damage provided by the present invention.

[0029] Figure 4 This is one of the cross-sectional views of the gas space structure of the module body provided by the present invention.

[0030] Figure 5 This is the second cross-sectional view of the gas space structure of the module body provided by the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] The structural schematic diagram of the first embodiment provided by the present invention is as follows Figure 1 As shown, the urea liquid supply module includes a urea tank 13, a urea supply pump 12, a metering nozzle 11, a module body 10, a urea liquid level sensor 43, a urea liquid temperature sensor 44, a urea liquid quality sensor 38, a urea liquid heating and thawing circulating water pipe 45 and a urea cleaning device 14.

[0033] The module body 10 is provided with a urea liquid outlet nozzle 20, a liquid return nozzle 25, and the water inlet and outlet nozzles (46, 47) of the heating and thawing circulating water pipe 45, a secondary urea liquid filter device 52 arranged upstream of the liquid outlet nozzle 20, and a mounting clip 16 for mounting and fixing the module 15 to the urea tank 13 after the module 15 is inserted from the upper part of the urea tank 13 into the urea tank 13. In addition, the module body 10 itself includes an internal liquid outlet channel 57 and a liquid return channel 26, internal water inlet and outlet channels (such as Figure 4 As shown, taking the inlet channel 300 as an example), the trapezoidal steps 58 of the annular axial array. The mounting buckle 16 includes a limiting hole 54a matched with the step 58 of the module body 10, a protrusion 54 matched with the installation limiting step 59a of the urea tank 13, and a through hole 55 that allows each pipeline of the urea liquid supply module 15 to pass through. The mounting buckle 16 is fixed to the module body 10 by a hugging manner, and at the same time limits each pipeline leading to the inside of the body and each sensor pipeline, ensuring the stability of each installation component, and the module 15 is installed in the urea tank installation hole 59 through the protrusion 54.

[0034] The secondary urea liquid filter device 52 is located upstream of the liquid outlet nozzle 20, and includes a cavity 52a with a threaded cover 52b and an internal filter element 52 arranged inside the cavity 52a. The cavity 52a is connected to the internal liquid outlet channel 57, and the urea liquid is filtered by the filter element 52 before being output. The filter element 52 can be replaced regularly, and its filtering accuracy is higher than that of the primary filter screen 32, so as to ensure the normal operation of the downstream metering nozzle 11 and improve the service life of the system.

[0035] The liquid supply pump 12 includes a liquid inlet 60 and a liquid outlet 29. The liquid inlet 60 is provided with a primary filter 32. The urea solution enters the supply pump 12 after being filtered through the primary filter 32 under the action of its own gravity. The primary filter 32 is clamped on the supply pump 12 through a buckle 31, and a vertical bubble exhaust pipe 33 is provided on it. In addition, a horizontal bubble exhaust pipe 30 is provided in the middle of the supply pump 12. The two bubble exhaust pipes (30, 33) are connected through a three-way pipe 41 and lead to the air gap space above the bottom plane of the module installation buckle 16. The three-way pipe 41 is partially provided with a primary filter 41a, so that when the urea liquid is frozen and thawed, the urea supply pump 12 can be fed with liquid through the first thawed primary filter 41a.

[0036] Further, if Figure 5 As shown, the outlet 29 of the supply pump 12 includes a step 401 with a flange 400, a gland 403 matched with the step, and the gland 403 includes a barb 404. The barb 404 is stuck on the flange 400 and forms a sealed cavity 406 through a sealing ring 402. A gas space 405 is provided in the cavity 406. The gas space 405 is a closed hollow volume made of a soft thin-walled material, and the material can be rubber.

[0037] The metering nozzle 11 includes a liquid inlet end 23 and a liquid return end 24. The liquid inlet end 23 is connected to the liquid outlet nozzle 20 via a liquid supply pipe 21. The liquid return end 24 is connected to the liquid return nozzle 25 via a liquid return pipe 22. The other end of the liquid return nozzle 25 is connected to a liquid return channel 26, and leads to a certain depth inside the urea tank 13 through the liquid return channel 26.

[0038] The above-mentioned liquid outlet 29 is connected to the internal liquid outlet channel 57 of the module body 10 through a liquid outlet pipe 28. The liquid outlet pipe 28 is a molded pipe designed to be as close to the heating and thawing circulating water pipe 45 as possible. A sealing gasket 56 is installed between the liquid outlet pipe 28 and the liquid outlet channel 57 to seal and reduce shock. The internal liquid outlet channel 57 leads to the liquid outlet nozzle 20.

[0039] The urea liquid supply pump 12 and the urea liquid quality sensor 38 are located at the bottom of the module 15, fixed on the urea liquid heating and thawing circulating water pipe 45, and arranged in a way that is conducive to ice melting. The urea liquid heating and thawing circulating water pipe 45 is a bottom L-shaped pipe, and a platform 34 with a positioning hole 35 is included between the L-shaped pipes, which is conducive to the urea supply pump 12 and the urea liquid quality sensor 38 being fixed at the same height position of the module 15, and can be inserted into the bottom of the urea tank 13 through the module mounting hole 59 of the urea tank 13. The quality sensor 38 includes a step 40 with a threaded hole 40a corresponding to the positioning hole 35, and is fixed to the platform 34 by a bolt 36. The urea liquid level sensor 43 and the urea liquid temperature sensor 44 are fixed through the module 15 and extend into the urea tank 13 close to the urea supply pump 12.

[0040] Combination Figure 4 As shown, the heating and thawing circulating water pipe 45 is connected to the heating and thawing circulating water pipe inlet and outlet nozzles (46, 47) through the internal inlet and outlet water channels (taking the water inlet channel 300 as an example) of the module body 10. A gas space 301 is provided on the internal inlet and outlet water channels 300 of the module body 10 to prevent the circulating water system from bursting when water freezes. A water pipe sleeve 302 and a shock-absorbing sleeve 304 are provided at the end of the heating and thawing circulating water pipe 45 to fix and protect the heating and thawing circulating water pipe 45. The circulating water pipe 45 and the module body 10 are sealed by a sealing ring 303.

[0041] The urea cleaning device 14 includes a diaphragm air pump 49 and a cleaning pipeline 17. The module body 10 includes an air path 48. The cleaning pipeline 17 includes an air inlet 49a and an air outlet 51. The air inlet 49a is connected to the gas space above the urea tank 13 through the air path 48 of the module body 10. A one-way valve 50 is provided on the air outlet 51, and is unidirectionally connected to the liquid outlet pipe 28. When necessary, the air pump 49 is started to suck air from the urea tank 13 to pressurize and open the one-way valve 50. The pressurized gas passes through the air inlet 49a, the liquid outlet pipe 28, the liquid supply pipe 21, and the liquid return pipe 22 in sequence, and can draw most of the urea liquid in each pipeline back to the urea tank 13.

[0042] Figure 2The second embodiment structural diagram provided by the present invention is different from the first embodiment structural diagram provided by the present invention in that: the module body 10 is provided with a urea re-drawing device 18, including a re-drawing valve 100 and a re-drawing pipeline 18a. The re-drawing pipeline 18a includes an ejection cavity 101, a drainage channel 104 that leads to a certain depth of the urea tank 13, a liquid inlet 103 and a liquid outlet 102. The re-drawing valve 100 is a one-way valve opened by electromagnetic force, and the ejection cavity 101 is a space that is conducive to the rapid flow of urea liquid back from the drainage channel 104 when the re-drawing valve 100 is opened. At the same time, the space is also conducive to the liquid in the outlet pipe 28 entering the drainage channel 104. The urea re-drawing device 18 is connected in series to the internal liquid outlet channel 57 through the liquid inlet channel 103 and the liquid outlet channel 102. In the normal spraying state, the urea liquid in the internal liquid outlet channel 57 directly reaches the liquid outlet nozzle 20 through the liquid inlet and outlet channels (102, 103) of the urea re-drawing device 18 and is then output. When the pipeline needs to be cleaned, the re-drawing valve 100 is started, and the urea liquid enters the drainage channel 104 through the liquid inlet channel 103 at a certain speed, so that a certain vacuum degree is generated in the injection cavity 101, so that most of the urea liquid in the liquid supply pipe 21 and the return pipe 22 is drawn back to the urea tank 13.

[0043] In the structure described in this embodiment, the extension section of the module internal liquid return channel 26 is arranged in the gas space above the urea tank 13 to ensure that there is no back suction phenomenon in the pipeline during back pumping.

[0044] Figure 3 The third embodiment of the present invention is different from the first embodiment of the present invention in that: the module body 10 is provided with a urea tank 13 atmospheric pipeline 200 and a nozzle 201. One end of the urea tank 13 atmospheric pipeline is connected to the nozzle 201, and the other end extends into the urea tank 13 to a certain depth H. The purpose is to prevent the urea tank 13 from being overfilled when the filling port is higher than the module body 10, and to balance the air pressure in the urea tank 13. In this structural embodiment, the air inlet 49a of the cleaning device can be directly connected to the atmosphere to simplify the pipeline design.

[0045] The above embodiments are only used to illustrate the essence of the present invention, but not to limit the present invention. Any modification, simplification and other replacement methods made without departing from the principle of the present invention are included in the protection scope of the present invention.

[0046] The present invention does not involve parts that are the same as the prior art or can be implemented by using the prior art.

Claims

1. A urea liquid supply module for preventing liquid from freezing and damaging, comprising a module body, a urea supply pump, a urea liquid level sensor, a urea liquid temperature sensor, a heating and thawing circulating water pipe, a water inlet nozzle, and a water outlet nozzle, wherein a circulating water flow channel is arranged inside the module body, and the heating and thawing circulating water pipe is connected with the heating and thawing circulating water pipe inlet and outlet nozzles through the circulating water flow channel, characterized in that: The urea liquid supply module is provided with more than one gas space, one of the gas spaces is provided on the circulating water flow channel, and the second gas space is provided on the urea supply pump. When the circulating water or the working liquid freezes and expands in volume, the gas in the gas space is compressed and releases the volume, thereby preventing the components from being damaged when the circulating water or the working liquid freezes. One of the gas spaces is a bulging space with a certain height, which is connected to the circulating water channel at the bottom but is closed at the top. The downward connecting channel at the bottom is large enough so that the liquid entering the bulging space can smoothly return to the circulating water channel by relying on its own gravity and overcoming the resistance of bubbles. The second gas space is a closed hollow volume made of a soft thin-walled material. When the surrounding pressure increases, the closed hollow volume is compressed and releases volume.

2. The urea liquid supply module according to claim 1, characterized in that: The enclosed hollow volume is made of rubber material.

3. The urea liquid supply module according to claim 1, characterized in that: The total volume of the gas space is greater than or equal to the expansion volume of the liquid in the supply module when it freezes.

4. The urea liquid supply module according to claim 3, characterized in that: One of the gas spaces is arranged at the water inlet end or the water outlet end of the heating and thawing circulating water pipe.

5. The urea liquid supply module according to claim 3, characterized in that: The second gas space is arranged near the liquid outlet to meet the expansion space requirement of the working liquid in the module after freezing.

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