A porous urea solution injection valve

Abstract

The present invention belongs to the technical field of after-treatment of exhaust gas of internal combustion engines, and discloses a porous urea solution injection valve, including a liquid inlet pipe, a central magnet, a guide pipe, a needle valve steel ball assembly, an electromagnetic coil, a valve seat and a spray hole plate, wherein the valve seat is sealed and fixed to one end of the guide pipe away from the central magnet, the valve seat is provided with a liquid outlet hole and a circular groove, the liquid outlet hole is connected to a liquid accumulation cavity, the needle valve steel ball assembly can abut against the valve seat to block the liquid outlet hole, the circular groove is connected to the liquid outlet hole, the spray hole plate is arranged at one end of the valve seat away from the needle valve steel ball assembly, and the spray hole plate and the circular groove form an acceleration cavity, the spray hole plate is provided with a plurality of spray holes, and the spray holes are connected to the circular groove. When the urea solution is sprayed out of the spray hole, a lateral velocity is formed under the action of the acceleration cavity, and a certain lateral velocity increases the interaction between the liquid beam and the air, accelerates the tearing of the liquid beam, reduces the atomized particle size, optimizes the spray distribution, improves the spray uniformity, and avoids the occurrence of urea crystallization.

Description

Technical Field

[0001] The invention relates to the technical field of after-treatment of exhaust gas from an internal combustion engine, and in particular to a porous urea solution injection valve. Background Art

[0002] As diesel engine emission regulations become increasingly stringent, the post-treatment system needs to use a selective catalytic reduction system (SCR) to remove nitrogen oxides contained in the exhaust gas. Usually, a 32.5% urea aqueous solution is injected into the exhaust pipe, and ammonia is formed through hydrolysis and pyrolysis. The nitrogen oxides are then catalytically reduced to harmless nitrogen and water through a catalytic carrier to achieve the purpose of exhaust gas treatment.

[0003] The urea solution injection system is a low-pressure injection system. Without air assistance, the existing atomizer structure is difficult to achieve a good atomization effect, and the spray particle size is large. When such a urea solution is sprayed into the exhaust pipe, it is easy to form a liquid film on the nozzle head, mixer and pipe wall, which will cause urea crystallization, block the exhaust pipe, cause excessive exhaust emissions, and even damage the engine in severe cases.

[0004] Therefore, a porous urea solution injection valve is urgently needed to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a porous urea solution injection valve to solve the problems of poor atomization effect, uneven distribution and large spray particle size in the injection valve used in the selective catalytic conversion system of a diesel engine in the prior art.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A porous urea solution injection valve, comprising:

[0008] A liquid inlet pipe, wherein a first channel is opened in the liquid inlet pipe;

[0009] A central magnet, wherein the central magnet is sealed and fixed to the liquid inlet pipe, a second channel is opened in the central magnet, the second channel is connected to the first channel, and a spring is arranged in the second channel;

[0010] A guide tube, one end of which is sealed and fixed to the central magnet, and a liquid accumulation cavity is provided in the guide tube;

[0011] A needle valve steel ball assembly, wherein the needle valve steel ball assembly is slidably disposed in the liquid accumulation chamber, and one end of the needle valve steel ball assembly is in contact with the spring, and a third channel is opened in the needle valve steel ball assembly, and the third channel is respectively connected with the second channel and the liquid accumulation chamber;

[0012] An electromagnetic coil, the electromagnetic coil is arranged on the outer surface of the central magnet and the guide tube, and the electromagnetic coil can control the needle valve steel ball assembly to slide in a direction close to the central magnet;

[0013] A valve seat, the valve seat is sealed and fixed to one end of the guide tube away from the central magnet, the valve seat is provided with a liquid outlet hole and a circular groove, the liquid outlet hole is communicated with the liquid accumulation cavity, the needle valve steel ball assembly can abut against the valve seat to block the liquid outlet hole, and the circular groove is communicated with the liquid outlet hole;

[0014] A spray hole plate is arranged at one end of the valve seat away from the needle valve steel ball assembly, and the spray hole plate and the circular groove form an acceleration chamber. The spray hole plate is provided with a plurality of spray holes, and the spray holes are connected to the circular groove.

[0015] Preferably, a groove is formed at one end of the orifice plate away from the valve seat, a plurality of the injection holes are evenly distributed along the central circumference of the orifice plate, and the injection holes are formed within the boundary of the groove.

[0016] Preferably, the boundary of the circular groove is larger than the boundary of the injection hole.

[0017] Preferably, the needle valve steel ball assembly includes a needle valve stem and a steel ball component, the steel ball component is arranged at one end of the needle valve stem away from the central magnet, the third channel is opened in the needle valve stem, and a plurality of flow holes are opened on the needle valve stem, the flow holes connect the third channel and the liquid accumulation chamber, and the steel ball component can abut against the valve seat to seal the liquid outlet hole.

[0018] Preferably, the steel ball part is evenly provided with a plurality of flattened positions along the circumferential direction, and the surface areas of the plurality of flattened positions are equal.

[0019] Preferably, a guide hole and a conical surface are further provided on the valve seat, the guide hole guides the sliding path of the needle valve steel ball assembly, the conical surface is arranged at one end of the liquid outlet close to the needle valve steel ball assembly, and the steel ball part can fit with the conical surface.

[0020] Preferably, the steel ball component and the guide hole form a liquid storage chamber, and the steel ball component and the liquid outlet hole form a liquid outlet chamber. When the steel ball component contacts the conical surface, a seal is formed, and the liquid storage chamber is separated from the liquid outlet chamber. When there is a gap between the steel ball component and the conical surface, the liquid storage chamber is connected to the liquid outlet chamber.

[0021] Preferably, the second channel includes an inner hole and a center hole opened in the central magnet, the inner hole is connected to the center hole, a filter is arranged in the inner hole, an adjustment sleeve is arranged in the center hole, and both ends of the spring are respectively abutted against the adjustment sleeve and the needle valve steel ball assembly.

[0022] Preferably, the adjustment sleeve is interference fit with the center hole, and the compression amount of the spring can be adjusted by adjusting the position of the adjustment sleeve in the center hole.

[0023] Preferably, a positioning step is provided at one end of the guide tube away from the central magnet, the valve seat is penetrated through the end of the guide tube away from the central magnet, and one end of the valve seat abuts against the positioning step.

[0024] Beneficial effects of the present invention:

[0025] The porous urea solution injection valve provided by the present invention can control the on and off of the magnetic force of the central magnet by controlling the on and off of the voltage signal input by the electromagnetic coil. When the voltage signal is input by the electromagnetic coil, the magnetic force generated by the central magnet is greater than the compression force of the spring and the liquid pressure of the urea solution entering through the liquid inlet pipe. The needle valve steel ball assembly moves upward under the action of the central magnet, and the urea solution enters the acceleration chamber through the first channel, the second channel, the third channel, the liquid accumulation chamber and the liquid outlet hole in sequence. The urea solution forms a lateral velocity through the acceleration chamber and is finally ejected through the injection hole. When the urea solution is ejected from the injection hole, the lateral velocity is formed under the action of the acceleration chamber. A certain lateral velocity increases the interaction between the liquid beam and the air, accelerates the tearing of the liquid beam, and promotes the fragmentation of the urea solution, thereby forming a good atomization effect, reducing the atomization particle size, optimizing the spray distribution, improving the spray uniformity, and avoiding the occurrence of urea crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a porous urea solution injection valve provided by the present invention;

[0027] Figure 2 yes Figure 1 A partial enlarged view of the middle A;

[0028] Figure 3 It is a structural schematic diagram of the valve seat in the present invention;

[0029] Figure 4 It is a structural schematic diagram of the spray hole plate in the present invention.

[0030] In the figure:

[0031] 100, liquid inlet pipe; 101, first channel; 200, central magnet; 201, second channel; 2011, inner hole; 2012, central hole; 202, spring; 203, filter; 204, adjustment sleeve; 300, guide tube; 301, liquid accumulation chamber; 302, positioning step; 400, needle valve steel ball assembly; 401, third channel; 402, needle valve stem; 4021, flow hole; 403, steel ball part; 4031, flat position; 500, electromagnetic coil; 600, valve seat; 601, liquid outlet hole; 602, circular groove; 603, acceleration chamber; 604, guide hole; 605, cone; 606, liquid storage chamber; 607, liquid outlet chamber; 608, gap; 700, spray plate; 701, spray hole; 702, groove. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0033] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0035] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0036] like Figures 1 to 4 As shown, this embodiment provides a porous urea solution injection valve, including a liquid inlet pipe 100, a central magnet 200, a guide pipe 300, a needle valve steel ball assembly 400, an electromagnetic coil 500, a valve seat 600 and a spray hole plate 700, wherein a first channel 101 is opened in the liquid inlet pipe 100, and the first channel 101 is used for the urea solution to enter; the central magnet 200 is sealed and fixed to the liquid inlet pipe 100, and a second channel 201 is opened in the central magnet 200, and the second channel 201 is connected to the first channel The guide tube 300 is connected to the central magnet 200, and a spring 202 is arranged in the second channel 201; one end of the guide tube 300 is sealed and fixed to the central magnet 200, and a liquid accumulation chamber 301 is opened in the guide tube 300; the needle valve steel ball assembly 400 is slidably arranged in the liquid accumulation chamber 301, and one end of the needle valve steel ball assembly 400 abuts against the spring 202, and the spring 202 abutting against the needle valve steel ball assembly 400 is in a compressed state, and a third channel 401 is opened in the needle valve steel ball assembly 400, and the third channel 401 is respectively connected to the second channel 201 and the liquid accumulation chamber 301 are connected; the electromagnetic coil 500 is arranged on the outer surface of the central magnet 200 and the guide tube 300, and the electromagnetic coil 500 can control the needle valve steel ball assembly 400 to slide in the direction close to the central magnet 200; the valve seat 600 is sealed and fixed to the end of the guide tube 300 away from the central magnet 200, and the valve seat 600 is provided with a liquid outlet hole 601 and a circular groove 602, the liquid outlet hole 601 is connected to the liquid accumulation chamber 301, and the first channel 101, the second channel 201, and the third channel 401, the liquid accumulation chamber 301 and the liquid outlet hole 601 form a solution channel, the needle valve steel ball assembly 400 can abut against the valve seat 600 to block the liquid outlet hole 601, thereby disconnecting the solution channel, and the circular groove 602 is connected with the liquid outlet hole 601; the spray hole plate 700 is arranged at one end of the valve seat 600 away from the needle valve steel ball assembly 400, and an acceleration chamber 603 is formed between the spray hole plate 700 and the circular groove 602, and the spray hole plate 700 is provided with a plurality of spray holes 701, and the spray holes 701 are connected with the circular groove 602.

[0037] The porous urea solution injection valve provided in this embodiment can control the on and off of the magnetic force of the central magnet 200 by controlling the on and off of the voltage signal input to the electromagnetic coil 500. When the electromagnetic coil 500 inputs a voltage signal, the magnetic force generated by the central magnet 200 is greater than the compression force of the spring 202 and the liquid pressure of the urea solution entering through the liquid inlet pipe 100. The needle valve steel ball assembly 400 moves upward under the action of the central magnet 200, and the urea solution passes through the first channel 101, the second channel 201, the third channel 401, the liquid accumulation cavity 301 and the liquid outlet hole 601 in sequence to enter the acceleration cavity 603. The urea solution forms a lateral speed through the acceleration cavity 603 and is finally sprayed out through the injection hole 701. When the electromagnetic coil 500 disconnects the voltage signal, the needle valve steel ball assembly 400 moves downward under the action of the compression force of the spring 202 and the hydraulic pressure of the urea solution, and the needle valve steel ball assembly 400 abuts against the valve seat 600 and blocks the liquid outlet hole 601. When the urea solution is sprayed out of the injection hole 701, a lateral velocity is formed under the action of the acceleration chamber 603. A certain lateral velocity improves the interaction between the liquid beam and the air, accelerates the tearing of the liquid beam, and promotes the breakup of the urea solution, thereby forming a good atomization effect, reducing the atomized particle size, optimizing the spray distribution, improving the spray uniformity, and avoiding the occurrence of urea crystallization.

[0038] In the present embodiment, the central magnet 200 is provided with an inner hole 2011 and a central hole 2012, the inner hole 2011 and the central hole 2012 are connected to form a second channel 201, a filter screen 203 is provided in the inner hole 2011, an adjustment sleeve 204 is provided in the central hole 2012, and the two ends of the spring 202 are respectively in contact with the adjustment sleeve 204 and the needle valve steel ball assembly 400. By providing the filter screen 203, the urea solution entering the second channel 201 can be filtered to prevent urea crystals or other particles from entering the porous urea solution injection valve and causing blockage; by providing the adjustment sleeve 204 in the central hole 2012, it can ensure that the urea solution passes through the second channel 201 smoothly, and the spring 202 can be limited.

[0039] Specifically, the adjustment sleeve 204 is interference fit with the center hole 2012, which improves the stability and firmness of the adjustment sleeve 204 in the center hole 2012. By adjusting the position of the adjustment sleeve 204 in the center hole 2012, the compression amount of the spring 202 can be adjusted, so that the needle valve steel ball assembly 400 can smoothly abut against the valve seat 600 to block the liquid outlet 601 to meet the urea solution of different hydraulic conditions. At the same time, it can avoid the spring 202 being compressed too much and the elastic force being too large, causing the needle valve steel ball assembly 400 to abut against the valve seat 600 and causing impact and damage to the valve seat 600.

[0040] More specifically, the outer surface of the filter screen 203 is interference fit with the inner hole 2011 to improve the stability and firmness of the filter screen 203 in the central hole 2012 and prevent the filter screen 203 from being washed away by the urea solution when the urea solution flows.

[0041] In this embodiment, a positioning step 302 is provided at one end of the guide tube 300 away from the central magnet 200, and the valve seat 600 is passed through the end of the guide tube 300 away from the central magnet 200, and one end of the valve seat 600 abuts against the positioning step 302. By providing the positioning step 302, one end of the valve seat 600 abuts against the positioning step 302, thereby limiting the position of the valve seat 600 in the extending direction of the guide tube 300, and achieving the positioning effect of the valve seat 600.

[0042] The needle valve steel ball assembly 400 in this embodiment includes a needle valve stem 402 and a steel ball part 403. The steel ball part 403 is arranged at one end of the needle valve stem 402 away from the central magnet 200. The third channel 401 is opened in the needle valve stem 402. The needle valve stem 402 is provided with a plurality of flow holes 4021. The flow holes 4021 connect the third channel 401 and the liquid accumulation chamber 301. The steel ball part 403 can abut against the valve seat 600 to block the liquid outlet hole 601. Through the above structure, the urea solution in the third channel 401 can smoothly enter the liquid accumulation chamber 301.

[0043] Preferably, the plurality of flow holes 4021 are evenly distributed on the circumference of the needle valve rod 402, so that the needle valve steel ball assembly 400 is balanced when the urea solution flows, and the number of the flow holes 4021 is preferably 2. The steel ball component 403 is evenly provided with a plurality of flat positions 4031 along the circumference, and the surface areas of the plurality of flat positions 4031 are equal. Through the above structure, the urea solution can smoothly flow into the liquid outlet 601, and the number of the flat positions 4031 can be 3-5, preferably 4.

[0044] The electromagnetic coil 500 , the central magnet 200 and the needle valve steel ball assembly 400 in this embodiment form an electromagnetic circuit.

[0045] The valve seat 600 in this embodiment is also provided with a guide hole 604 and a conical surface 605. The guide hole 604 guides the sliding path of the needle valve steel ball assembly 400. The conical surface 605 is arranged at one end of the liquid outlet 601 close to the needle valve steel ball assembly 400, and the steel ball 403 can fit with the conical surface 605. Through the above structure, the sliding path of the needle valve steel ball assembly 400 is guided, and the needle valve steel ball assembly 400 is prevented from deflecting during the sliding process, and the steel ball 403 is ensured to accurately fit with the conical surface 605. When the steel ball 403 fits with the conical surface 605, the steel ball 403 blocks the liquid outlet 601.

[0046] Specifically, a liquid storage chamber 606 is formed between the steel ball member 403 and the guide hole 604, and a liquid outlet chamber 607 is formed between the steel ball member 403 and the liquid outlet hole 601. When the steel ball member 403 contacts the conical surface 605, a seal is formed, and the liquid storage chamber 606 and the liquid outlet chamber 607 are separated. When a gap 608 exists between the steel ball member 403 and the conical surface 605, the liquid storage chamber 606 is connected to the liquid outlet chamber 607. The urea solution passes through the liquid storage chamber 606, the gap 608, the liquid outlet chamber 607 and the acceleration chamber 603, forms a lateral velocity in the acceleration chamber 603, and then is ejected from the injection hole 701.

[0047] In this embodiment, a groove 702 is provided at one end of the orifice plate 700 away from the valve seat 600, and a plurality of injection holes 701 are evenly distributed along the central circumference of the orifice plate 700, and the injection holes 701 are provided within the boundary of the groove 702. By adjusting the depth of the groove 702 and the aspect ratio of the injection holes 701, the structure is simple, the processing difficulty is reduced, and the manufacturing cost is lower. Specifically, the groove 702 in this embodiment can be circular or in other shapes; the number of injection holes 701 can be 3-8, preferably 6.

[0048] Optionally, the boundary of the circular groove 602 is larger than the boundary of the injection hole 701 . Through the above structure, the urea solution can be fully accelerated in the acceleration chamber 603 to achieve a better acceleration effect, and can ensure that the urea solution laterally accelerated through the acceleration chamber 603 is sprayed out from the injection hole 701 .

[0049] In summary, the above-mentioned porous urea solution injection valve is used to control the on-off of the voltage signal input by the electromagnetic coil 500, and the electromagnetic force generated by the electromagnetic circuit formed by the electromagnetic coil 500, the central magnet 200, and the needle valve steel ball assembly 400, the compression force of the spring 202, the hydraulic pressure, etc., to realize the reciprocating motion of the needle valve steel ball assembly 400, and further control the connection between the liquid storage chamber 606 and the liquid outlet chamber 607. When there is a gap 608 between the steel ball 403 and the cone 605, the urea solution passes through the liquid storage chamber 606. The cavity 606, the gap 608 and the liquid outlet cavity 607 enter the acceleration cavity 603 formed by the valve seat 600 and the orifice plate 700. The urea solution forms a transverse velocity through the acceleration cavity 603. A certain transverse velocity improves the interaction between the liquid beam and the air, accelerates the tearing of the liquid beam, and promotes the breakup of the urea solution, thereby forming a good atomization effect. The aspect ratio of the injection hole 701 is accurately controlled by the groove 702 at the bottom of the orifice plate 700. The structure is simple, the processing difficulty is reduced, and the manufacturing cost is lower.

[0050] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A porous urea solution injection valve, characterized in that: include: A liquid inlet pipe (100), wherein a first channel (101) is provided in the liquid inlet pipe (100); a central magnet (200), the central magnet (200) being sealed and fixed to the liquid inlet pipe (100), a second channel (201) being provided in the central magnet (200), the second channel (201) being communicated with the first channel (101), and a spring (202) being provided in the second channel (201); A guide tube (300), one end of which is sealed and fixed to the central magnet (200), and a liquid accumulation cavity (301) is provided in the guide tube (300); A needle valve steel ball assembly (400), wherein the needle valve steel ball assembly (400) is slidably disposed in the liquid accumulation chamber (301), and one end of the needle valve steel ball assembly (400) is in contact with the spring (202); a third channel (401) is provided in the needle valve steel ball assembly (400), and the third channel (401) is communicated with the second channel (201) and the liquid accumulation chamber (301) respectively; an electromagnetic coil (500), the electromagnetic coil (500) being arranged on the outer surface of the central magnet (200) and the guide tube (300), and the electromagnetic coil (500) being capable of controlling the needle valve steel ball assembly (400) to slide in a direction close to the central magnet (200); A valve seat (600), the valve seat (600) is sealed and fixed to one end of the guide tube (300) away from the central magnet (200), the valve seat (600) is provided with a liquid outlet hole (601) and a circular groove (602), the liquid outlet hole (601) is communicated with the liquid accumulation cavity (301), the needle valve steel ball assembly (400) can abut against the valve seat (600) to block the liquid outlet hole (601), and the circular groove (602) is communicated with the liquid outlet hole (601); A spray hole plate (700), the spray hole plate (700) being arranged at one end of the valve seat (600) away from the needle valve steel ball assembly (400), and the spray hole plate (700) and the circular groove (602) forming an acceleration chamber (603), the spray hole plate (700) being provided with a plurality of spray holes (701), and the spray holes (701) being in communication with the circular groove (602); A groove (702) is provided at one end of the orifice plate (700) away from the valve seat (600), a plurality of the injection holes (701) are evenly distributed along the central circumference of the orifice plate (700), and the injection holes (701) are provided within the boundary of the groove (702); The boundary of the circular groove (602) is larger than the boundary of the injection hole (701); The needle valve steel ball assembly (400) comprises a needle valve stem (402) and a steel ball component (403), wherein the steel ball component (403) is arranged at one end of the needle valve stem (402) away from the central magnet (200), the third channel (401) is opened in the needle valve stem (402), a plurality of flow holes (4021) are opened on the needle valve stem (402), and the flow holes (4021) are connected to the third channel (401) and the liquid accumulation chamber (301), and the steel ball component (403) can abut against the valve seat (600) to block the liquid outlet hole (601); The steel ball part (403) is evenly provided with a plurality of flattened positions (4031) along the circumferential direction, and the surface areas of the plurality of flattened positions (4031) are equal; The valve seat (600) is also provided with a guide hole (604) and a conical surface (605), wherein the guide hole (604) guides the sliding path of the needle valve steel ball assembly (400), and the conical surface (605) is arranged at one end of the liquid outlet hole (601) close to the needle valve steel ball assembly (400), and the steel ball component (403) can fit with the conical surface (605); The steel ball component (403) and the guide hole (604) form a liquid storage chamber (606), and the steel ball component (403) and the liquid outlet hole (601) form a liquid outlet chamber (607). When the steel ball component (403) contacts the conical surface (605), a seal is formed, and the liquid storage chamber (606) is separated from the liquid outlet chamber (607). When a gap (608) exists between the steel ball component (403) and the conical surface (605), the liquid storage chamber (606) is connected to the liquid outlet chamber (607).

2. The porous urea solution injection valve according to claim 1, characterized in that: The second channel (201) comprises an inner hole (2011) and a center hole (2012) opened in the central magnet (200); the inner hole (2011) is connected to the center hole (2012); a filter screen (203) is arranged in the inner hole (2011); an adjustment sleeve (204) is arranged in the center hole (2012); and two ends of the spring (202) are respectively in contact with the adjustment sleeve (204) and the needle valve steel ball assembly (400).

3. The porous urea solution injection valve according to claim 2, characterized in that: The adjustment sleeve (204) is interference-fitted with the center hole (2012), and the compression amount of the spring (202) is adjusted by adjusting the position of the adjustment sleeve (204) in the center hole (2012).

4. The porous urea solution injection valve according to any one of claims 1 to 3, characterized in that: A positioning step (302) is provided at one end of the guide tube (300) away from the central magnet (200), the valve seat (600) is passed through the end of the guide tube (300) away from the central magnet (200), and one end of the valve seat (600) is in contact with the positioning step (302).

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