Electronic expansion valve and small flow working condition precision regulation method

Abstract

The present application relates to the technical field of expansion valve for controlling refrigerant applied in air conditioner heat management system, and particularly discloses an electronic expansion valve and a small-flow working condition precision regulation method. The electronic expansion valve comprises a valve island, a valve body and a valve core. The inside of the valve core is further provided with a guide cavity in communication with the threaded connection cavity on one side of the sealing cone surface. The electronic expansion valve further comprises a guide structure in axial movable connection with the guide cavity. At least in the small-flow working condition when the sealing cone surface is matched with the valve port, the guide structure is abutted to the position coaxial with the valve port and opposite to the valve port in the lower flow channel of the valve island, so as to stably position and guide the valve core. The valve core will not appear deflection and shaking, the stability of the coaxial consistency of the flow passage and the valve port is good, the stability of the intercepting action is better, unnecessary shaking and noise are reduced, the precise controllability of the large-flow electronic expansion valve in the small-flow working condition is realized, and the use range of the electronic expansion valve is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of expansion valves for controlling refrigerants in air conditioning thermal management systems, and in particular to an electronic expansion valve and a small-flow operating condition precision control method. BACKGROUND

[0002] With the application of R744 refrigerant in automobile air conditioners, existing automobile air conditioners and thermal management systems require components to meet higher operating pressures and greater refrigerant flow. The more intelligent human-machine interaction and system thermal management of electric vehicles also require higher control direction and control precision of refrigerant fluid.

[0003] A bidirectional electronic expansion valve is disclosed in Chinese Utility Model Patent No. CN216789271U, which meets the needs of bidirectional refrigerant flow and high-pressure sealing. The above-mentioned patent discloses a bidirectional electronic expansion valve, the valve body of which is installed on the valve island in a plug-in manner. The valve body includes a rotor housing, a rotor seat sleeve, and a valve seat. A valve core guide structure is provided between the rotor seat sleeve and the flange of the valve core. A sealing assembly is provided between the valve core and the valve seat. The sealing assembly not only seals but also guides the axial movement of the valve core.

[0004] The bidirectional electronic expansion valve disclosed in the above-mentioned patent has the valve core guide structure and the sealing assembly located away from the valve port. Since the length and stroke of the valve core are relatively long, when the valve core moves to a small opening of the valve port, i.e., in a small-flow operating condition, the thread pair, valve core guide structure, and sealing assembly are all far away from the free end of the valve core. The valve core assumes a cantilevered state, and under the action of high-pressure fluid, the free end of the valve core will slightly deflect, causing the flow-blocking surface between the valve core and the valve port to be asymmetric relative to the center axis. This leads to poor control precision and stability of the valve in a small-flow operating condition, and the refrigerant flow fluctuates significantly, resulting in unnecessary shaking and noise. SUMMARY

[0005] The technical problem to be solved by the present application is to provide an electronic expansion valve with improved structure and a small-flow operating condition precision control method to solve the technical defects of poor control precision and stability of existing electronic expansion valves in a small-flow operating condition, significant fluctuations in refrigerant flow, and unnecessary shaking and noise.

[0006] To solve the above technical problems, the technical solution provided by the present application is as follows: an electronic expansion valve, at least comprising:

[0007] a valve island, the valve island being provided with a valve body mounting cavity, a lower flow channel communicating with the bottom of the valve body mounting cavity, and a side flow channel communicating with the side of the valve body mounting cavity, the bottom of the valve body mounting cavity being provided with a valve port;

[0008] A valve body is installed in a valve body mounting cavity. The valve body includes at least a drive component, a rotor sleeve, and a valve seat. The output end of the drive component is provided with a screw.

[0009] A valve core is provided with a sealing assembly between the valve core and the valve seat. A sealing cone surface adapted to the valve port is provided on the outer side of the valve core near the lower end. A threaded connection cavity adapted to the screw is provided inside the valve core.

[0010] The valve core also has a guide cavity on one side of the sealing cone surface that communicates with the threaded connection cavity, and includes a guide structure that is axially movably connected to the guide cavity. At least in the case of low flow rate when the sealing cone surface is adapted to the valve port, the guide structure abuts against the lower flow channel of the valve island at a position coaxial with and opposite to the valve port. A pressure equalization channel is provided between the guide structure and the inner wall of the guide cavity.

[0011] In a preferred embodiment, the guide structure includes, from bottom to top, a positioning part, a connecting rod, and a guide part. The guide part is located inside the guide cavity and is axially slidably connected to the guide cavity. A limiting structure for confining the guide part within the guide cavity is provided at the port of the guide cavity. A gap is provided between the limiting structure and the connecting rod. A spring is provided inside the guide cavity on the side of the guide part away from the positioning part. A positioning groove coaxial with the valve port and adapted to the positioning part is provided in the lower flow channel of the valve island.

[0012] In a preferred embodiment, a mounting post is provided on the side of the guide portion away from the positioning portion, the lower end of the spring is sleeved on the mounting post, a stepped surface is provided at the end of the guide cavity near the threaded connection cavity, and the upper end of the spring abuts against the stepped surface.

[0013] In a preferred embodiment, the positioning part is conical or hemispherical, and the positioning groove is conical or spherical and adapted to the positioning part.

[0014] In a preferred embodiment, the guide portion is provided with at least one pressure equalization cross-section or pressure equalization groove axially penetrating the guide portion along the circumferential direction.

[0015] In a preferred embodiment, the limiting structure is a narrowed portion formed by narrowing the end of the valve core.

[0016] In a preferred embodiment, the limiting structure includes a mounting groove disposed at the port of the guide cavity and a limiting end cap fixedly installed in the mounting groove. The outer diameter of the limiting end cap is larger than the inner diameter of the guide cavity, and the inner diameter of the limiting end cap is larger than the outer diameter of the connecting rod.

[0017] A preferred embodiment, the guide structure comprises a fixed segment and a guide segment in turn, the fixed segment is fixedly connected with the position in the lower flow channel of the valve island coaxial with the valve port and opposite, the guide segment extends coaxially with the valve port from the fixed segment to the position where the valve port is located, the guide segment is movably connected with the guide cavity, the outer wall of the guide segment is provided with an equalizing surface, and the equalizing surface and the inner wall of the guide cavity form an equalizing channel.

[0018] The small flow working condition precision regulation method of the electronic expansion valve of the embodiment at least includes the following steps:

[0019] Step A: the state that the sealing cone surface of the valve core is away from the valve port, that is, the full open state of the valve port, the guide part of the guide structure is in abutting contact with the limiting structure under the action of the spring, and the positioning part of the guide structure is not in contact with the positioning groove of the valve island.

[0020] Step B: after the valve core moves downward to the position where the lower end or the position close to the lower end of the sealing cone surface cooperates with the valve port, the positioning part of the guide structure cooperates with the positioning groove of the valve island.

[0021] Step C: during the movement process that the valve core continues to move downward to the closed state of the valve port, the guide structure is in a stationary state, the guide cavity of the valve core moves relative to the guide part, and the spring is gradually compressed.

[0022] Step D: during the movement process that the valve core moves upward from the closed state of the valve port to the position where the lower end or the position close to the lower end of the sealing cone surface cooperates with the valve port, the guide structure is in a stationary state, the guide cavity of the valve core moves relative to the guide part, and the spring is gradually released.

[0023] Step E: after the valve core continues to move upward to the position where the sealing cone surface is separated from the valve port, the positioning part of the guide structure is separated from the positioning groove of the valve island, and the guide structure moves upward together with the valve core.

[0024] Another small flow working condition precision regulation method of the electronic expansion valve of the embodiment at least includes the following steps:

[0025] Step A: the state that the sealing cone surface of the valve core is away from the valve port, that is, the full open state of the valve port, the guide segment of the guide structure is in a separated state with the guide cavity of the valve core.

[0026] Step B: the lower end or the position close to the lower end of the sealing cone surface cooperates with the valve port, and the guide segment of the guide structure enters the guide cavity of the valve core.

[0027] Step C: during the movement process that the valve core is between the position in step B and the position where the valve port is closed, the guide cavity of the valve core moves axially relative to the guide segment of the guide structure.

[0028] The electronic expansion valve and the small flow working condition precision control method of the embodiment, through the guide cavity arranged in the valve core and the guide structure axially movably connected with the guide cavity, in the small flow working condition when the sealing cone surface is matched with the valve port, the guide structure is abutted to the position in the lower flow passage of the valve island coaxial and opposite to the valve port, which plays a stable positioning and guiding role on the valve core, the valve core will not appear deflection and shaking, so that the stability of the coaxial consistency of the flow passage and the valve port is better, and then the stability of the flow cutting action is better, unnecessary shaking and noise are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The structure schematic diagram of the electronic expansion valve shown in embodiment one, wherein the valve port is in the maximum opening state;

[0030] Figure 2 The structure schematic diagram of the electronic expansion valve shown in embodiment one, wherein the sealing cone surface of the valve core is matched with the valve port;

[0031] Figure 3 The structure schematic diagram of the electronic expansion valve shown in embodiment one, wherein the valve port is in the closed state;

[0032] Figure 4 The external structure schematic diagram of the valve core assembly in the first kind of implementation of the electronic expansion valve shown in embodiment one;

[0033] Figure 5 The exploded state structure schematic diagram of the valve core assembly shown in embodiment one; Figure 4

[0034] The cross-sectional structure schematic diagram of the valve core assembly shown in embodiment one; Figure 6 Figure 4 The structure schematic diagram of the valve core in the valve core assembly shown in embodiment one;

[0035] Figure 7 Figure 4 The guide structure schematic diagram of the first kind of implementation in the valve core assembly shown in embodiment one;

[0036] Figure 8 The position of the guide part in the valve core assembly shown in embodiment one; Figure 4

[0037] The guide structure schematic diagram of the second kind of implementation in the valve core assembly shown in embodiment one; Figure 9 Figure 4 The cross-sectional schematic diagram of the position of the guide part in the valve core assembly shown in embodiment one;

[0038] Figure 10 Figure 4 The guide structure schematic diagram of the second kind of implementation in the valve core assembly shown in embodiment one;

[0039] Figure 11 ​​​​The explosion state structure schematic diagram of the valve core assembly of the second embodiment of the electronic expansion valve shown in the embodiment one;

[0040] Figure 12 The structure schematic diagram of the valve core in the valve core assembly shown in the embodiment one; Figure 11 The structure schematic diagram of the valve core in the valve core assembly shown in the embodiment one;

[0041] Figure 13 The structure schematic diagram of the valve core in the valve core assembly shown in the embodiment one; Figure 11 The structure schematic diagram of the valve core in the embodiment one;

[0042] Figure 14 The structure schematic diagram of the valve core in the embodiment one; Figure 11 The structure schematic diagram of the valve core in the embodiment one;

[0043] Figure 15 The flow curve diagram of the prior art electronic expansion valve;

[0044] Figure 16 The flow curve diagram of the electronic expansion valve shown in the embodiment one;

[0045] Figure 17 The structure schematic diagram of the electronic expansion valve shown in the embodiment two;

[0046] Figure 18 The structure schematic diagram of the guide structure in the electronic expansion valve shown in the embodiment two. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0048] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0049] In the description of the present application, it should be understood that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, integral connection, or detachable connection; it can be the communication inside two elements; it can be direct connection, or indirect connection through intermediate medium; for those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] In the description of this invention, it should be noted that the abutment can be a non-fixed contact fit or a fixed connection describing the state.

[0051] Example 1

[0052] An electronic expansion valve of this embodiment, such as Figures 1-3 As shown, it includes a valve island A0 and a valve body V0. The valve island A0 is provided with a valve body mounting cavity A5, a lower flow channel A2 communicating with the bottom of the valve body mounting cavity A5, and a side flow channel A3 communicating with the side of the valve body mounting cavity. A valve port A1 is provided at the bottom of the valve body mounting cavity. It should be noted that the structure of this valve island A0 is prior art and will not be described in detail here; for example, the valve island disclosed in CN216789271U.

[0053] In this embodiment, the valve body V0 is installed in the valve body mounting cavity A5. The valve body V0 includes a driving component V3, a rotor seat V1, and a valve seat V2. The output end of the driving component V3 is provided with a screw V31, which is used to drive the valve core 10 to move axially. It should be noted that the structure of the valve body V0 described above is prior art, such as the valve body disclosed in CN216789271U, and will not be described in detail in this embodiment.

[0054] As a special feature of this embodiment, a valve core assembly is also provided, which is installed within the valve body V0. The valve core assembly of the first embodiment of this invention is as follows: Figures 4-6 As shown, it includes a valve core 10, a guide structure 20, and a spring 30. The structure of the valve core 10 is as follows: Figure 7 As shown, it includes a valve core body 11, with a flange 12 on the outer side of its upper end. A guide pair V4 is provided between the flange 12 and the rotor seat V1. A sealing assembly V5 is provided between the valve core 10 and the valve seat V2. A sealing cone surface 13 is provided on the outer side of the valve core 10 near the lower end.

[0055] In this embodiment, the valve core 10 has a guide cavity 15 located on one side of the sealing cone surface 13 and a threaded connection cavity 14 located on the side away from the sealing cone surface. The threaded connection cavity 14 communicates with the guide cavity 15. The threaded connection cavity 14 is used to connect with the screw V31 of the drive assembly to drive the axial movement of the valve core.

[0056] Preferably, in this embodiment, a transition cavity 16 is provided between the guide cavity 15 and the threaded connection cavity 14. The inner diameter of the transition cavity 16 is smaller than the inner diameter of the guide cavity 15, so that a stepped surface 17 is formed at the end of the guide cavity 15 near the threaded connection cavity 14.

[0057] In this embodiment, the structure of the guide structure 20 is as follows: Figure 8As shown in the figure, the guiding structure comprises, from bottom to top, a positioning part 23, a connecting rod 22 and a guiding part 21. The guiding part 21 is located in the guiding cavity 15 and is in axial sliding connection with the guiding cavity 15.

[0058] In this embodiment, the guiding structure of the first embodiment is as shown in the figure. Figure 8 、 Figure 9 As shown in the figure, the guiding part 21 is provided with two pressure-equalizing sections 25 which axially penetrate the guiding part 21 in the circumferential direction. The pressure-equalizing sections 25 form pressure-equalizing channels 26 with the inner wall of the guiding cavity 15, so as to balance the pressure in the cavities on the upper and lower sides of the guiding part 21 during the movement of the guiding part 21 in the guiding cavity 15.

[0059] In this embodiment, the guiding structure of the second embodiment is as shown in the figure. Figure 10 As shown in the figure, the guiding part 21 is provided with four pressure-equalizing grooves 27 which axially penetrate the guiding part 21 in the circumferential direction. The pressure-equalizing grooves 27 form pressure-equalizing channels with the inner wall of the guiding cavity 15.

[0060] It should be noted that the above two pressure-equalizing channel formation modes are preferred embodiments of the present embodiment, but are not the only limitation.

[0061] In this embodiment, the spring 30 is located in the guiding cavity 15 and is arranged on the side of the guiding part 21 away from the positioning part 23. The lower end of the spring 30 abuts against the guiding part 21, and the upper end abuts against the stepped surface 17. As a preferred mode, the side of the guiding part 21 away from the positioning part 23 is provided with a mounting column 24, and the lower end of the spring 30 is sleeved on the mounting column 24. In this embodiment, the spring functions to provide certain damping to avoid the guiding structure from shaking relative to the valve core.

[0062] In this embodiment, the outer diameter of the connecting rod 22 is smaller than the outer diameter of the guiding part 21, and a limiting structure for limiting the guiding part 21 in the guiding cavity 15 is arranged at the port of the guiding cavity 15. As a preferred mode, as shown in the figure, Figure 6 、 Figure 7 the limiting structure of the present embodiment is a necked part 18 formed by necking processing of the end of the valve core 10. The inner diameter of the necked part 18 is greater than the outer diameter of the connecting rod 22, so that a gap 28 is formed between the necked part 18 and the connecting rod 22, which functions the same as the pressure-equalizing channel to keep the air pressure balanced. The inner diameter of the necked part 18 is smaller than the outer diameter of the guiding part 21, so that the guiding part 21 can only move axially in the guiding cavity 15.

[0063] In this embodiment, the positioning part 23 is conical. Correspondingly, as shown in the figure, Figure 1As shown, the lower flow channel A2 of the valve island is provided with a positioning groove A4 coaxial with the valve port A1 and used for adapting with the positioning part 23, which is conical for adapting with the positioning part. Of course, the conical shape is only the preferred embodiment of the present embodiment, and the positioning part 23 can also be a ball head structure with a hemispherical shape, and correspondingly, the positioning groove A4 is a ball socket structure for adapting with the ball head structure.

[0064] The second embodiment of the valve core assembly of the present embodiment is different from the first embodiment in that the limiting structure is different. Specifically, as shown in the figure, Figures 11-14 As shown, the limiting structure includes a mounting groove 19 arranged at the guide cavity port and a limiting end cover 40 fixedly installed in the mounting groove 19.

[0065] The limiting end cover 40 includes a body 41 with an outer contour adapted to the mounting groove 19, and the outer diameter of the body 41 is greater than the inner diameter of the guide cavity 15. The limiting end cover 40 is provided with an inner hole 42, and the inner diameter of the inner hole 42 is greater than the outer diameter of the connecting rod 22, and the gap 28 is formed between the inner hole 42 and the connecting rod 22.

[0066] In the present embodiment, the mounting mode between the limiting end cover and the mounting groove can be any one of the existing technologies such as interference fit, welding, and gluing.

[0067] The small flow condition precision control method of the electronic expansion valve shown in the present embodiment includes the following steps:

[0068] Step A: As shown in the figure, Figure 1 The sealing cone surface of the valve core is away from the valve port, i.e. the valve port is fully open, the guide part of the guide structure is in abutting contact with the limiting structure under the action of the spring, and the positioning part of the guide structure is not in contact with the positioning groove of the valve island.

[0069] Step B: As shown in the figure, Figure 2 After the valve core moves downward to the position where the lower end or the position close to the lower end of the sealing cone surface cooperates with the valve port, the positioning part of the guide structure cooperates with the positioning groove of the valve island.

[0070] Step C: The valve core continues to move downward to Figure 3 In the movement process of the valve port closing, the guide structure is in a static state, the guide cavity of the valve core moves relative to the guide part, and the spring is gradually compressed.

[0071] In this step C, the electronic expansion valve is in the small flow condition as the valve port is closing, and the valve core is not inclined and shaken due to the guiding structure which stably guides the valve core, so that the stability of the coaxial consistency of the flow passage and the valve port is good, and the stability of the cutting action is ensured, and unnecessary shaking and noise are reduced.

[0072] Step D: In the movement process of the valve core from the closed state of the valve port to the lower end or the position close to the lower end of the sealing cone surface cooperating with the valve port, the guiding structure is in a static state, the guiding cavity of the valve core moves relative to the guiding part, and the spring is gradually released.

[0073] Step E: After the valve core continues to move upward to the position where the sealing cone surface is disengaged from the valve port, the positioning part of the guiding structure is disengaged from the positioning groove of the valve island, and the guiding structure moves upward together with the valve core.

[0074] The flow curve of the prior art electronic expansion valve is shown in Figure 15 , and the flow has obvious fluctuations when the valve port opening is small, that is, in the small flow condition. In contrast, the flow curve of the electronic expansion valve of the present embodiment is shown in Figure 16 , and obviously, the stability of the flow is better, so that the precise control of the electronic expansion valve with large flow in the small flow condition is realized, and the use range of the electronic expansion valve is expanded.

[0075] Example Two

[0076] The electronic expansion valve of the present embodiment is different from that of Example One in that the guiding structure is different. Specifically, as shown in Figure 17 , Figure 18 , the guiding structure 20 includes a fixed segment 53 and a guiding segment 51 in sequence. The fixed segment 53 is fixedly connected to the position coaxial with the valve port A1 in the lower flow passage A2 of the valve island A0. The guiding segment 51 is coaxial with the valve port from the fixed segment 53 and extends upward to the position of the valve port, and the guiding segment 51 is movably connected to the guiding cavity 15.

[0077] In the present embodiment, the outer wall of the guiding segment 51 is provided with an equalizing surface 52, and the equalizing surface 52 forms an equalizing channel with the inner wall of the guiding cavity 15.

[0078] As a preferred, the free end of the guiding segment 51 is further provided with a transition segment 54 with a smaller diameter.

[0079] The small flow condition precision control method of the electronic expansion valve of the present embodiment includes the following steps:

[0080] Step A: the sealing cone of the valve core is away from the valve port, i.e. the valve port is fully open, and the guiding section of the guiding structure is separated from the guiding cavity of the valve core.

[0081] Step B: the lower end or the position close to the lower end of the sealing cone is matched with the valve port, and the guiding section of the guiding structure enters the guiding cavity of the valve core. Figure 17

[0082] Step C: during the movement of the valve core between the position of Step B and the position of the closed valve port, the guiding cavity of the valve core moves axially relative to the guiding section of the guiding structure.

[0083] In the embodiment, based on the fixed guiding structure 20, when the electronic expansion valve is in the small flow working condition, the valve core will not be inclined and shaken due to the stable positioning and guiding effect of the guiding structure on the valve core, the stability of the coaxial consistency of the flow passage and the valve port is good, and the stability of the flow cutting action is further ensured, thereby reducing unnecessary shaking and noise.

[0084] In summary, the above only describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. An electronic expansion valve, comprising at least: The valve island is provided with a valve body mounting cavity, a lower flow channel communicating with the bottom of the valve body mounting cavity, and a side flow channel communicating with the side of the valve body mounting cavity. A valve port is provided at the bottom of the valve body mounting cavity. A valve body is installed in a valve body mounting cavity. The valve body includes at least a drive component, a rotor sleeve, and a valve seat. The output end of the drive component is provided with a screw. A valve core is provided with a sealing assembly between the valve core and the valve seat. A sealing cone surface adapted to the valve port is provided on the outer side of the valve core near the lower end. A threaded connection cavity adapted to the screw is provided inside the valve core. The valve core is characterized in that a guide cavity communicating with the threaded connection cavity is provided on one side of the sealing cone surface, and a guide structure is axially movably connected to the guide cavity. At least in the case of low flow rate when the sealing cone surface is adapted to the valve port, the guide structure abuts against the lower flow channel of the valve island at a position coaxial with and opposite to the valve port. A pressure equalization channel is provided between the guide structure and the inner wall of the guide cavity.

2. The electronic expansion valve according to claim 1, characterized in that, The guide structure includes, from bottom to top, a positioning part, a connecting rod, and a guide part. The guide part is located inside the guide cavity and is axially slidably connected to the guide cavity. A limiting structure is provided at the port of the guide cavity to restrict the guide part within the guide cavity. A gap is provided between the limiting structure and the connecting rod. A spring is provided inside the guide cavity on the side of the guide part away from the positioning part. A positioning groove is provided in the lower flow channel of the valve island, which is coaxial with the valve port and is used to adapt to the positioning part.

3. The electronic expansion valve according to claim 2, characterized in that, A mounting post is provided on the side of the guide portion away from the positioning portion. The lower end of the spring is sleeved on the mounting post. A stepped surface is provided at the end of the guide cavity near the threaded connection cavity. The upper end of the spring abuts against the stepped surface.

4. The electronic expansion valve according to claim 2, characterized in that, The positioning part is conical or hemispherical, and the positioning groove is conical or spherical to fit the positioning part.

5. The electronic expansion valve according to claim 2, characterized in that, The guide section is provided with at least one pressure equalization surface or pressure equalization groove that penetrates the guide section axially along the circumferential direction.

6. The electronic expansion valve according to any one of claims 2-5, characterized in that, The limiting structure is a narrowed section formed by narrowing the end of the valve core.

7. The electronic expansion valve according to any one of claims 2-5, characterized in that, The limiting structure includes a mounting groove disposed at the port of the guide cavity and a limiting end cap fixedly installed in the mounting groove. The outer diameter of the limiting end cap is larger than the inner diameter of the guide cavity, and the inner diameter of the limiting end cap is larger than the outer diameter of the connecting rod.

8. The electronic expansion valve according to claim 1, characterized in that, The guiding structure includes a fixed section and a guiding section in sequence. The fixed section is fixedly connected to the lower flow channel of the valve island at a position coaxial with and opposite to the valve port. The guiding section extends upward from the fixed section, coaxial with the valve port, to the position of the valve port. The guiding section is adapted to and movably connected to the guiding cavity. The outer wall of the guiding section is provided with a pressure equalizing surface, and a pressure equalizing channel is formed between the pressure equalizing surface and the inner wall of the guiding cavity.

9. A method for adjusting the accuracy of the electronic expansion valve under low flow conditions according to any one of claims 2-7, characterized in that, At least the following steps are included: Step A: When the sealing cone surface of the valve core is far away from the valve port, i.e. the valve port is fully open, the guide part of the guide structure is in contact with the limiting structure under the action of the spring, and the positioning part of the guide structure is not in contact with the positioning groove of the valve island. Step B: After the valve core descends to the lower end or near the lower end of the sealing cone surface and engages with the valve port, the positioning part of the guide structure contacts and engages with the positioning groove of the valve island. Step C: During the downward movement of the valve core until the valve port is closed, the guide structure is stationary, the guide cavity of the valve core moves relative to the guide part, and the spring is gradually compressed; Step D: During the movement of the valve core from the closed state to the lower end or near the lower end of the sealing cone surface to cooperate with the valve core, the guide structure is in a stationary state, the guide cavity of the valve core moves relative to the guide part, and the spring is gradually released; Step E: After the valve core continues to move upward until the sealing cone surface disengages from the valve port, the positioning part of the guide structure disengages from the positioning groove of the valve island, and the guide structure moves upward together with the valve core.

10. A method for precise control of the electronic expansion valve under low flow conditions as described in claim 8, characterized in that, At least the following steps are included: Step A: The sealing cone surface of the valve core is far away from the valve port, i.e., the valve port is fully open, and the guide section of the guide structure is disengaged from the guide cavity of the valve core. Step B: The lower end of the sealing cone surface or the position near the lower end mates with the valve port, and the guide section of the guide structure enters the guide cavity of the valve core; Step C: During the movement of the valve core between the position in step B and the position of the valve port in the closed state, the guide cavity of the valve core moves axially relative to the guide section of the guide structure.

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