An electronic expansion valve

Abstract

This invention relates to an electronic expansion valve, comprising a drive assembly, a screw, a valve needle, a valve seat, a bearing, and a valve needle spring. The valve seat has a fluid passage. The drive assembly drives the screw to rotate and move axially. The valve needle has an axial mounting hole inside, and its upper part has a bearing cavity to accommodate the bearing. The lower end of the screw extends into the axial mounting hole and is rotatably connected to the bearing, allowing for axial sliding. A screw retaining ring is provided at its lower end, and a screw annular protrusion is provided on its outer periphery. The valve needle spring is sleeved on the screw and confined between the screw annular protrusion and the upper end face of the valve needle. Downward movement of the screw compresses the valve needle spring through the screw annular protrusion, pushing the valve needle downward. Upward movement of the screw pushes the valve needle upward through the screw retaining ring against the bearing, thereby achieving stable axial movement of the valve needle to precisely control the opening and closing of the fluid passage. This structure achieves pure axial transmission through the bearing, effectively preventing the valve needle from rotating and vibrating with the screw. The compact layout of the valve needle spring significantly shortens the axial dimension of the valve body, improving transmission reliability and service life.

Description

Technical Field

[0001] This invention relates to the field of expansion valve technology, and more specifically to an electronic expansion valve. Background Technology

[0002] As a core throttling element in a refrigeration system, the performance of the electronic expansion valve directly affects the system's energy efficiency and operational stability. Traditional electronic expansion valves typically use a magnetic rotor to drive a screw to rotate, and then convert the screw's rotational motion into the linear motion of the valve needle through a threaded pair (nut assembly), thereby adjusting the valve opening and controlling the flow rate.

[0003] However, if the valve needle is directly connected via a screw, the screw will cause the valve needle to rotate, and the valve needle is susceptible to axial vibration or radial oscillation due to fluid impact, leading to unstable flow regulation. Therefore, existing technologies also use a valve needle sleeve assembly to achieve axial transmission and buffering (see the specification of Chinese Utility Model Patent No. CN218480789U "An Electronic Expansion Valve"; and the full text of Chinese Utility Model Patent No. CN221647613U "A Valve Needle Assembly for an Electronic Expansion Valve"). This addition of a valve needle sleeve assembly... In this design, the screw and valve needle are typically connected by a valve needle sleeve and bushing to achieve axial transmission only. A spring is used to buffer the connection between the screw and valve needle. However, this design requires ensuring lubrication at the rotating connection of the valve needle sleeve and bushing, and also requires axial installation space between the screw and valve needle for the spring and the positioning structures at both ends of the spring. This increases the complexity of the electronic expansion valve assembly and the overall length. Furthermore, the stability of the axial transmission between the screw and valve needle depends on the stability of the valve needle sleeve assembly, which requires high assembly precision for the valve needle sleeve assembly.

[0004] Therefore, there is an urgent need in this field for an electronic expansion valve with a simple and compact structure, smooth and reliable transmission, and effective suppression of valve needle vibration, so as to improve the reliability of the electronic expansion valve while simplifying its structure and shortening its overall length. Summary of the Invention

[0005] The purpose of this invention is to develop an electronic expansion valve to solve the problems of high complexity of the axial transmission structure between the screw and the valve needle, high assembly precision requirements, and increased overall length of the electronic expansion valve due to axial installation space in the prior art. The invention aims to improve the stability and reliability of axial transmission while simplifying the structure of the electronic expansion valve and shortening its length.

[0006] This invention is achieved through the following technical solution: An electronic expansion valve includes a drive assembly, a screw, a valve needle, a valve seat, a bearing, and a valve needle spring. The valve seat has a fluid passage. The drive assembly drives the screw to rotate and move axially, causing the screw to drive the valve needle to move axially relative to the valve seat, thereby opening or blocking the fluid passage. The valve needle has an axial mounting hole, and the upper part of the axial mounting hole has a bearing cavity. The bearing is housed in the bearing cavity and is axially limited. The lower part of the screw extends into the axial mounting hole and slides axially with the bearing. The lower end of the screw is located below the bearing and is fixed with a screw retaining ring. The outer periphery of the screw has a radially protruding screw annular protrusion, and the screw annular protrusion is located above the valve needle. The valve needle spring is sleeved on the screw and limited between the screw annular protrusion and the upper end face of the valve needle. When the screw moves axially downward, the screw ring compresses the valve needle spring downward, and the valve needle spring pushes the valve needle axially downward. When the screw moves axially upward, the screw retaining ring pushes the bearing upward, and the bearing pushes the valve needle axially upward. The advantages of the above technical solution are: the lower part of the screw drives the valve needle axially through the bearing housed in the bearing cavity of the valve needle, avoiding the screw from driving the valve needle to rotate. The smoothness of the bearing rotation is reliable and controllable. The assembly precision requirement of the bearing in the bearing cavity is low (ensuring the bearing cavity limits the axial position of the bearing meets the assembly requirements), reducing the risk of jamming when the screw and valve needle rotate relative to each other, and facilitating production and assembly; the lower end of the screw extends directly into the axial mounting hole of the valve needle, and the valve needle spring is sleeved on the screw and limited to the upper end of the screw ring and the valve needle. The design eliminates the need for a valve needle spring installation limit structure, thus reducing installation length. Simultaneously, by utilizing the valve needle spring and screw retaining ring to push the valve needle during the screw's axial downward and upward movements, respectively, the axial transmission between the screw and valve needle becomes more direct and stable. After the valve needle spring pushes the valve needle downward to block the fluid, the screw continues to move downward a certain distance to compress the valve needle spring, allowing it to accumulate elastic potential energy to maintain the valve needle in the fluid-blocking position. This effectively suppresses valve needle vibration and provides a stable rebound force for subsequent valve needle opening.

[0007] Specifically, the bearing configuration ensures low-friction axial transmission between the screw and the valve needle, improving transmission efficiency and stability, reducing the coaxiality requirement between the screw and the valve needle (the bearing only needs to be able to transmit axial force), enhancing the reliability of the electronic expansion valve and extending its service life. The valve needle spring is sleeved outside the screw, with the lower end of the screw extending into the axial mounting hole of the valve needle. The valve needle spring only contacts the top surface of the valve needle at its lower end, effectively reducing the incidence of valve needle wear and jamming caused by spring misalignment during operation, significantly extending the lifespan of the expansion valve. Therefore, the above structure makes the overall structure of the electronic expansion valve compact, eliminating the need for a large spring mounting space, simplifying the original valve needle sleeve assembly structure, shortening the overall length of the electronic expansion valve, and improving its reliability and stability. Furthermore, a bearing retaining ring is fixedly connected to the top of the valve needle, and the bearing is located below the bearing retaining ring; a relatively sliding bushing is sleeved on the lower part of the screw, and the bushing is located within the inner ring of the bearing retaining ring; the valve needle spring is located between the screw annular protrusion and the upper end face of the bushing.

[0008] Furthermore, the screw includes a large-diameter section located below the screw annular convexity and a small-diameter section extending downward from the large-diameter section. The outer diameter of the large-diameter section is larger than the inner diameter of the bushing, and the outer diameter of the small-diameter section is less than or equal to the inner diameter of the bushing. The small-diameter section has a clearance fit with the inner ring of the bearing. The length of the valve needle spring in its natural state is greater than the length of the large-diameter section. The bearing retainer and bushing not only provide axial restraint for the bearing, ensuring stable installation of the bearing within the valve needle, but also achieve precise axial transmission between the screw and the valve needle through their cooperation with the large-diameter and small-diameter sections of the screw. Specifically, since the length of the valve needle spring in its natural state is greater than the length of the large-diameter section, when the screw moves axially downward, the valve needle spring first contacts the bushing. As the valve needle spring is compressed by the screw annular convexity, the lower end of the large-diameter section gradually approaches the bushing. Because the outer diameter of the large-diameter section is larger than the inner diameter of the bushing, the large-diameter section cannot pass through the bushing, thus limiting the maximum compression of the valve needle spring. Meanwhile, the small-diameter section of the screw extends from the inner ring of the bushing into the axial balance through hole, and is clearance-fitted with the bearing to achieve a rotating connection. This ensures that the screw can drive the valve needle to move axially while rotating, without causing the valve needle to rotate with the screw. This prevents the screw from driving the valve needle to rotate when the valve body is closed, which could cause internal leakage failure due to sealing friction between the valve needle and the valve base. It also reduces the concentricity requirement between the valve base and the valve needle during valve body installation.

[0009] In one feasible embodiment, the valve seat is provided with an upper valve seat cavity, a partition, and a lower valve seat cavity from top to bottom. The upper part of the valve needle extends into the upper valve seat cavity and engages with the screw drive. The middle part of the valve needle slides and seals with the partition. The lower part of the valve needle extends into the lower valve seat cavity to open or close the fluid passage. By dividing the valve seat into an upper valve seat cavity, a partition, and a lower valve seat cavity, the valve needle can move precisely axially within each cavity. The upper part of the valve needle extending into the upper valve seat cavity and engaging with the screw drive ensures that the rotation of the screw is effectively transmitted to the valve needle, driving it to move axially. The middle part of the valve needle slides and seals with the partition, ensuring the stability of the valve needle during movement and preventing fluid leakage inside the valve seat. The lower part of the valve needle extending into the lower valve seat cavity, through its axial movement, opens or closes the fluid passage, thereby achieving precise control of the fluid flow rate. This design makes the electronic expansion valve more compact in structure and improves its operational stability and reliability. Furthermore, a side balance hole is provided on the side wall of the valve needle, located below the bearing cavity. The axial mounting hole is a through hole axially penetrating the valve needle, and the side balance hole connects the axial mounting hole and the upper cavity of the valve seat. The axial mounting hole of the valve needle, as an axial balance through hole, serves to connect the lower cavity and the upper cavity of the valve seat, allowing for rapid balance of internal and external pressures during valve opening and closing, thus reducing resistance. Furthermore, an annular groove is provided on the partition, and an inner sealing ring of the valve seat is provided within the annular groove for sliding sealing cooperation with the valve needle. The annular groove is located on the upper surface of the partition, and a sealing retainer ring is fixedly provided on the upper surface of the partition to axially limit the inner sealing ring of the valve seat. The valve needle passes through the sealing retainer ring, and the inner sealing ring of the valve seat is fixed within the annular groove using a riveting process. In one feasible implementation, the drive assembly includes a magnetic shielding tube and a magnetic rotor assembly and a nut assembly disposed within the magnetic shielding tube. The upper part of the screw is linked to the magnetic rotor assembly. The magnetic rotor assembly is electromagnetically driven to rotate, thereby causing the screw to rotate relative to the nut assembly and then move axially relative to the nut assembly. The lower end of the magnetic shielding tube is fixedly connected to the upper end of the valve seat.

[0010] Furthermore, the nut assembly includes a nut body, the lower outer peripheral wall of which is provided with a positioning protrusion and / or a positioning groove, and the upper inner wall of the valve seat is provided with a valve seat groove or valve seat protrusion for positioning and engaging with the positioning protrusion or positioning groove; this prevents the nut body from slipping and rotating circumferentially relative to the valve seat, improving product stability; a nut balance hole is provided on the side wall of the nut body. This allows for rapid balance of internal air pressure, reducing energy consumption, making the screw and valve needle move more quickly, and reducing material usage. Finally, the valve seat is integrally formed, the fluid channel includes a radial through hole opened in the lower part of the valve seat, and a first valve seat outer sealing ring and a second valve seat outer sealing ring are embedded in the outer periphery of the valve seat, the first valve seat outer sealing ring and the second valve seat outer sealing ring are located on the upper and lower sides of the radial through hole respectively; both the first valve seat outer sealing ring and the second valve seat outer sealing ring are Step Seal rings. This is used to prevent internal leakage; a Step Seal is a high-performance one-way acting seal, widely used in structures such as hydraulic cylinder piston rods due to its unique stepped structure and excellent sealing performance. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall appearance of the electronic expansion valve in the embodiment; Figure 2 This is a cross-sectional view of the electronic expansion valve in the embodiment; Figure 3 This is a schematic diagram of the valve needle and its driving mechanism of the electronic expansion valve in the embodiment; Figure 4 for Figure 3 A cross-sectional view of the structure shown; Figure 5 for Figure 3 Schematic diagram of the connection between the screw and the valve needle.

[0012] In the diagram: 1. Magnetic shielding tube; 2. Magnetic rotor assembly; 3. Screw; 31. Screw annular protrusion; 32. Screw retaining ring; 33. Large diameter section; 34. Small diameter section; 4. Nut assembly; 41. Nut body; 42. Positioning protrusion; 43. Nut balance hole; 5. Valve needle; 51. Bearing retaining ring; 52. Bearing; 53. Bushing; 501. Axial mounting hole; 502. Balance hole; 6. Valve seat; 61. Valve seat inner sealing ring; 62. Valve seat annular protrusion; 63. Sealing retaining ring; 601. Valve seat lower cavity; 602. Valve seat upper cavity; 603. Separator; 604. Radial through hole; 7. Valve needle spring; 81. First valve seat outer sealing ring; 82. Second valve seat outer sealing ring. Detailed Implementation

[0013] First, those skilled in the art should understand that the following embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0014] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0015] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0016] To make the objectives, features and advantages of the present invention more apparent and understandable, specific embodiments are described in detail below with reference to the accompanying drawings.

[0017] like Figures 1 to 5 As shown, this embodiment provides an electronic expansion valve, including a drive assembly, a screw 3, a valve needle 5, a valve seat 6, a bearing 52, and a valve needle spring 7. The valve seat 6 has a fluid channel. The drive assembly drives the screw 3 to rotate while moving axially, thereby driving the valve needle 5 to open or close the fluid channel. The valve needle 5 has an axial mounting hole 501, and the upper part of the axial mounting hole 501 has a bearing cavity. The bearing 52 is housed in the bearing cavity and is axially limited. The lower part of the screw 3 extends into the axial mounting hole 501 and slides axially with the bearing 52. The lower end of the screw 3 is located below the bearing 52 and is fixed with a screw retainer ring 32. The screw 3 has a radially protruding screw ring 31 on its outer periphery, and the screw ring 31 is located above the valve needle 5. The valve needle spring 7 is sleeved on the screw 3 and is limited between the screw ring 31 and the upper end face of the valve needle 5. When the screw 3 moves axially downward, the screw ring 31 compresses the valve needle spring 7 downward, and the valve needle spring 7 pushes the valve needle 5 axially downward. When the screw 3 moves axially upward, the screw retaining ring 32 pushes the bearing 52 upward, and the bearing 52 pushes the valve needle 5 axially upward.

[0018] Furthermore, a bearing retaining ring 51 is fixedly connected to the top of the valve needle 5, and the bearing 52 is located below the bearing retaining ring 51; a relatively slidable bushing 53 is sleeved on the lower part of the screw 3, the bushing 53 is located within the inner ring of the bearing retaining ring 51, and the valve needle spring 7 is located between the upper end face of the screw annular protrusion 31 and the bushing 53. Specifically, the screw 3 includes a large-diameter section 33 located below the screw annular protrusion 31 and a small-diameter section 34 extending downward from the large-diameter section 33. The outer diameter of the large-diameter section 33 is larger than the inner diameter of the bushing 53, and the outer diameter of the small-diameter section 34 is less than or equal to the inner diameter of the bushing 53. The small-diameter section 34 has a clearance fit with the inner ring of the bearing 52; the length of the valve needle spring 7 in its natural state is greater than the length of the large-diameter section 33. The bearing retaining ring 51 and the bushing 53 not only provide axial restraint for the bearing 52, ensuring its stable installation within the valve needle 5, but also achieve precise axial transmission between the screw 3 and the valve needle 5 through their cooperation with the large-diameter section 33 and the small-diameter section 34 of the screw 3. Specifically, since the length of the valve needle spring 7 in its natural state is greater than the length of the large-diameter section 33, when the screw 3 moves axially downward, the valve needle spring 7 first contacts the bushing 53. As the valve needle spring 7 is compressed by the screw ring protrusion 31, the lower end of the large-diameter section 33 gradually approaches the bushing 53. Because the outer diameter of the large-diameter section 33 is greater than the inner diameter of the bushing 53, the large-diameter section 33 cannot pass through the bushing 53, thus limiting the maximum compression of the valve needle spring 7. Meanwhile, the small-diameter section 34 of the screw 3 extends from the inner ring of the bushing 53 into the axial mounting hole 501, and is clearance-fitted with the bearing 52 (ball bearing). This decouples the screw 3 from the bearing 52, ensuring that the screw 3 can drive the valve needle 5 to move axially while rotating, without causing the valve needle 5 to rotate with the screw 3. This prevents internal leakage failure caused by the screw driving the valve needle to rotate when the valve body is closed, which would result in sealing friction between the valve needle and the valve base. It also reduces the concentricity requirement between the valve base and the valve needle during valve body installation. Furthermore, the valve seat 6 is provided with an upper valve seat cavity 602, a partition 603, and a lower valve seat cavity 601 from top to bottom. The upper part of the valve needle 5 extends into the upper valve seat cavity 602 and is driven by the screw 3. The middle part of the valve needle 5 is in sliding sealing fit with the partition 603. The lower part of the valve needle 5 extends into the lower valve seat cavity 601 to conduct or block the fluid passage. The above-described design divides the interior of the valve seat 6 into an upper chamber 602, a partition 603, and a lower chamber 601, allowing the valve needle 5 to move precisely axially within each chamber. The upper part of the valve needle 5 extends into the upper chamber 602 and engages with the screw 3, ensuring that the rotation of the screw 3 is effectively transmitted to the valve needle 5, driving its axial movement. The middle part of the valve needle 5 slides and seals with the partition 603, ensuring the stability of the valve needle 5 during movement and preventing fluid leakage within the valve seat 6.The lower part of the valve needle 5 extends into the lower cavity 601 of the valve seat. Its axial movement opens or closes the fluid passage, thus achieving precise control of the fluid flow rate. This design makes the electronic expansion valve more compact in structure and improves its operational stability and reliability. Furthermore, a side balance hole 502 is provided on the side wall of the valve needle 5, located below the bearing cavity. The axial mounting hole 501 is a through hole axially penetrating the valve needle 5, and the side balance hole 502 connects the axial mounting hole 501 and the upper cavity 602 of the valve seat. The axial mounting hole 501 of the valve needle 5, in conjunction with the side balance hole 502, serves to connect the lower cavity 601 and the upper cavity 602 of the valve seat, allowing for rapid balance of internal and external pressures during valve opening and closing, reducing resistance to valve operation. Furthermore, the partition 603 is provided with an annular groove, and an inner sealing ring 61 of the valve seat is provided in the annular groove to slide and seal with the valve needle 5. The annular groove is opened on the upper surface of the partition 603, and a sealing retaining ring 63 is fixedly provided on the upper surface of the partition 603 to axially limit the inner sealing ring 61 of the valve seat. The valve needle 5 passes through the sealing retaining ring 63. In this embodiment, the inner sealing ring 61 of the valve seat is fixed in the valve seat 6 by a riveting process to reduce costs and increase efficiency. Specifically, structurally, a valve seat annular protrusion 62 is provided on the upper surface of the partition 603, and the valve seat annular protrusion 62 radially limits the outer periphery of the sealing retaining ring 63. In one embodiment, the driving assembly includes a magnetic shielding tube 1 and a magnetic rotor assembly 2 and a nut assembly 4 disposed within the magnetic shielding tube 1. The upper part of the screw 3 is linked to the magnetic rotor assembly 2. The structure of the magnetic rotor assembly 2 is prior art, and can be found in Chinese Utility Model Patent No. CN221647614U, "A Valve Body Assembly of an Electronic Expansion Valve," or Chinese Invention Application No. CN118746166A, "An Electronic Expansion Valve." Its specific structure will not be described in detail here. The magnetic rotor assembly 2 is electromagnetically driven to rotate, thereby causing the screw 3 to rotate relative to the nut assembly 4 and then move axially relative to the nut assembly 4. The lower end of the magnetic shielding tube 1 is fixedly connected to the upper end of the valve seat 6. Specifically, the nut assembly 4 includes a nut body 41. The lower outer peripheral wall of the nut body 41 is provided with a positioning protrusion 42 and / or a positioning groove. The upper inner wall of the valve seat 6 is provided with a valve seat groove or valve seat protrusion for positioning and engaging with the positioning protrusion 42 or the positioning groove, preventing the nut body 41 from slipping and rotating circumferentially relative to the valve seat 6, thus improving product stability. A nut balance hole 43 is provided on the side wall of the nut body 41, which can quickly balance the internal air pressure, reduce energy consumption, make the screw and valve needle move more quickly, and reduce material usage.In the above embodiments, the valve seat 6 is integrally formed, the fluid channel includes a radial through hole 604 opened in the lower part of the valve seat 6, and a first valve seat outer sealing ring 81 and a second valve seat outer sealing ring 82 are embedded on the outer periphery of the valve seat 6. The first valve seat outer sealing ring 81 and the second valve seat outer sealing ring 82 are respectively located on the upper and lower sides of the radial through hole 604; the first valve seat outer sealing ring 81 and the second valve seat outer sealing ring 82 are both Step Seal rings, used to prevent internal leakage. A Step Seal is a high-performance one-way sealing element. With its unique stepped structure and excellent sealing performance, it is widely used in structures such as hydraulic cylinder piston rods. Step Seal rings can be purchased, and their specific structure will not be described in detail here.

[0019] In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0020] In the description of this application, the reference to terms such as "this embodiment," "an embodiment," etc., means that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0021] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An electronic expansion valve comprising a drive assembly and a screw rod (3), a valve needle (5), a valve seat (6) provided with a fluid passage, the drive assembly driving the screw rod (3) to move axially while rotating, thereby driving the valve needle (5) to open or block the fluid passage. characterized in that Further comprising a bearing (52) and a valve needle spring (7). The valve needle (5) is provided with an axial mounting hole (501), and the upper part of the axial mounting hole (501) is provided with a bearing cavity, the bearing (52) is accommodated in the bearing cavity and is axially limited. The lower part of the screw rod (3) extends into the axial mounting hole (501) and axially slides with the bearing (52), and the lower end of the screw rod (3) is below the bearing (52) and is fixed with a screw rod stop ring (32). The outer periphery of the screw rod (3) is provided with a radially protruding screw rod ring (31), and the screw rod ring (31) is above the valve needle (5), the valve needle spring (7) is sleeved on the screw rod (3) and is limited between the screw rod ring (31) and the upper end surface of the valve needle (5). When the screw rod (3) moves axially downward, the screw rod ring (31) compresses the valve needle spring (7) downward, and the valve needle spring (7) pushes the valve needle (5) to move axially downward. When the screw rod (3) moves axially upward, the screw rod stop ring (32) pushes the bearing (52) upward, and the bearing (52) pushes the valve needle (5) to move axially upward.

2. The electronic expansion valve according to claim 1, characterized in that: The top end of the valve needle (5) is fixedly connected with a bearing stop ring (51), and the bearing (52) is limited below the bearing stop ring (51); the lower part of the screw rod (3) is sleeved with a shaft sleeve (53) which can slide relatively, the shaft sleeve (53) is limited in the inner ring of the bearing stop ring (51), and the valve needle spring (7) is limited between the screw rod ring (31) and the upper end surface of the shaft sleeve (53).

3. The electronic expansion valve according to claim 2, characterized in that: The screw rod (3) comprises a large diameter section (33) below the screw rod ring (31) and a small diameter section (34) extending downward from the large diameter section (33), the outer diameter of the large diameter section (33) is greater than the inner diameter of the shaft sleeve (53), the outer diameter of the small diameter section (34) is less than or equal to the inner diameter of the shaft sleeve (53), and the small diameter section (34) is in clearance fit with the inner ring of the bearing (52). The length of the valve needle spring (7) in the natural state is greater than the length of the large diameter section (33).

4. The electronic expansion valve of claim 1, wherein: The valve seat (6) is provided with a valve seat upper cavity (602), a separation part (603) and a valve seat lower cavity (601) from top to bottom, the upper part of the valve needle (5) extends into the valve seat upper cavity (602) and drives the screw rod (3), the middle part of the valve needle (5) is in sliding sealing fit with the separation part (603), and the lower part of the valve needle (5) extends into the valve seat lower cavity (601) to open or block the fluid passage.

5. The electronic expansion valve according to claim 4, characterized in that: The valve needle (5) has a side balance hole (502) located below the bearing cavity on its side wall. The axial mounting hole (501) is a through hole that axially penetrates the valve needle (5). The side balance hole (502) connects the axial mounting hole (501) and the upper cavity of the valve seat (602).

6. The electronic expansion valve according to claim 4, wherein: The partition (603) is provided with an annular groove, and the annular groove is provided with a valve seat inner sealing ring (61) that slides and seals with the valve needle (5). The valve seat inner sealing ring (61) is positioned and installed in the annular groove by a riveting process.

7. The electronic expansion valve according to claim 6, characterized in that: The annular groove is formed on the upper surface of the partition (603), and a sealing ring (63) is fixedly provided on the upper surface of the partition (603) to axially limit the inner sealing ring (61) of the valve seat, and the valve needle (5) passes through the sealing ring (63).

8. The electronic expansion valve of claim 1, wherein: The drive assembly includes a magnetic shielding tube (1) and a magnetic rotor assembly (2) and a nut assembly (4) disposed in the magnetic shielding tube (1). The upper part of the screw (3) is linked to the magnetic rotor assembly (2). The magnetic rotor assembly (2) is driven to rotate by electromagnetic drive to drive the screw (3) to rotate relative to the nut assembly (4) and then move axially relative to the nut assembly (4). The lower end of the magnetic shielding tube (1) is fixedly connected to the upper end of the valve seat (6).

9. The electronic expansion valve according to claim 8, characterized in that: The nut assembly (4) includes a nut body (41), the lower outer peripheral wall of the nut body (41) is provided with a positioning protrusion (42) and / or a positioning groove, the upper inner wall of the valve seat (6) is provided with a valve seat groove or valve seat protrusion for positioning and cooperating with the positioning protrusion (42) or the positioning groove; a nut balance hole (43) is provided on the side wall of the nut body (41).

10. Electronic expansion valve according to any of claims 1-9, characterized in that: The valve seat (6) is integrally formed, and the fluid channel includes a radial through hole (604) opened at the lower part of the valve seat (6). A first valve seat outer sealing ring (81) and a second valve seat outer sealing ring (82) are embedded on the outer periphery of the valve seat (6). The first valve seat outer sealing ring (81) and the second valve seat outer sealing ring (82) are respectively located on the upper and lower sides of the radial through hole (604). The first valve seat outer sealing ring (81) and the second valve seat outer sealing ring (82) are both Step seal rings.

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