Double-valve-needle electronic expansion valve and refrigeration equipment

Abstract

The utility model discloses a double-valve-needle electronic expansion valve and refrigeration equipment, and relates to the technical field of electronic expansion valves, the double-valve-needle electronic expansion valve comprises a large valve needle and a small valve needle, the end part of the large valve needle is provided with a sealing ring table, the sealing ring table is provided with a small valve port, the peripheral side of the large valve needle is provided with a lateral opening communicated with the small valve port, and the lateral opening is communicated with the small valve port. An elastic sealing piece is further arranged on the sealing ring table; the small valve needle can axially and movably penetrate through the large valve needle, and the small valve needle comprises a needle rod part and a valve needle part with the diameter smaller than that of the needle rod part; when the small valve needle is located at the closing position, the needle rod portion compresses the elastic sealing piece to form first-stage sealing, and the valve needle portion is inserted into the small valve port to form second-stage sealing. And the first-stage seal and the second-stage seal are sequentially arranged along a path from the medium flowing through the lateral opening to the small valve port. According to the technical scheme provided by the utility model, the problems of contact surface abrasion and sealing failure (inner leakage) caused by repeated opening and closing when the small valve needle and the small valve port are in hard contact sealing can be solved.

Description

Technical Field

[0001] This utility model relates to the field of electronic expansion valve technology, and in particular to a dual-valve needle electronic expansion valve and a refrigeration device. Background Technology

[0002] Traditional single-valve needle electronic expansion valves have gradually revealed their limitations when dealing with large flow regulation and precise control of small openings. Dual-valve needle electronic expansion valves have emerged to address this issue. Their core design concept is to decompose flow regulation into a two-stage control of "coarse adjustment + fine adjustment"—the outer valve needle is responsible for the main flow regulation under large stroke, while the inner valve needle compensates for the small opening range, thus taking into account both the wide flow range and the need for high-precision regulation.

[0003] In current dual-valve needle electronic expansion valves, during the low-flow regulation stage, the small valve needle and the small valve port are mainly sealed by abutting against each other, and the flow rate is adjusted by the distance between them. However, the small valve needle and the small valve port are in hard contact to seal and stop. As a result, during the valve opening and closing process, the small valve needle and the small valve port are in constant contact, which will cause wear and lead to excessive internal leakage. Utility Model Content

[0004] The main purpose of this invention is to propose a dual-valve needle electronic expansion valve and refrigeration equipment, which aims to solve the problems of wear, internal leakage, and even jamming caused by the hard contact sealing between the small valve needle and the small valve port in the small flow regulation stage of traditional dual-valve needle electronic expansion valves.

[0005] To achieve the above objectives, this utility model proposes a dual-valve needle electronic expansion valve, comprising:

[0006] A large valve needle, the end of which is provided with a sealing ring platform, the sealing ring platform having a small valve port, the circumference of which is provided with a lateral opening communicating with the small valve port, and the sealing ring platform also being provided with an elastic sealing element;

[0007] A small valve needle is axially movable and inserted inside the large valve needle. The small valve needle includes a needle shank portion and a valve needle portion with a diameter smaller than that of the needle shank portion.

[0008] When the small valve needle is in the closed position, the needle rod part presses against the elastic sealing element to form a first-level seal, and the valve needle part is inserted into the small valve port to form a second-level seal;

[0009] The first-stage seal and the second-stage seal are arranged sequentially along the path of the medium flowing through the lateral opening to the small valve port.

[0010] In one embodiment, the upper surface of the sealing ring platform is provided with a mounting groove, and the elastic seal is installed in the mounting groove and extends partially beyond the mounting groove.

[0011] In one embodiment, the depth of the mounting groove is 0.1mm-0.5mm.

[0012] In one embodiment, the height of the resilient seal is 0.4mm-0.8mm.

[0013] In one embodiment, the deformation of the elastic seal is 0.1mm-0.3mm.

[0014] In one embodiment, the sealing ring is embedded in the large valve needle and is injection molded integrally with the large valve needle.

[0015] In one embodiment, the sealing ring is made of polyphenylene sulfide; or the sealing ring is made of polyphenylene sulfide containing 10%-30% carbon fiber or glass fiber.

[0016] In one embodiment, the inlet end of the small valve port is provided with a valve port chamfer, and the connection between the valve needle part and the needle rod part forms a valve needle conical surface. When the small valve needle is in the closed position, the valve needle conical surface and the valve port chamfer are in close contact to form a second-stage seal.

[0017] In one embodiment, the radius of the valve port chamfer ranges from 0.2 mm to 1.0 mm.

[0018] In one embodiment, the angle between the valve needle cone surface and the bottom surface of the needle rod is 60°-70°.

[0019] In one embodiment, the first-stage seal has a first sealing surface, and the second-stage seal has a second sealing surface, wherein the tangent of the first sealing surface and the tangent of the second sealing surface form an angle in space.

[0020] In one embodiment, the dual-valve needle electronic expansion valve further includes:

[0021] Valve seat with a large valve port;

[0022] The connecting seat is fixedly connected to the valve seat;

[0023] A lead screw, which passes through the connecting seat, is connected to the connecting seat via a bearing, and is axially fixed and rotatably mounted on the connecting seat;

[0024] The rotor assembly includes a limiting plate, and the end of the lead screw is fixed to the limiting plate;

[0025] A nut is inserted through the connecting seat and threaded into the lead screw, and can move along the axial direction of the lead screw;

[0026] A resilient reset element is disposed within the valve seat;

[0027] When the small valve needle seals the small valve port, the elastic reset member causes the large valve needle to seal the large valve port.

[0028] When the lead screw rotates, the nut moves along the axial direction of the lead screw and drives the small valve needle to disengage from the small valve port, and through the abutment structure, drives the large valve needle to disengage from the large valve port.

[0029] This utility model also proposes a refrigeration device, including the dual-valve needle electronic expansion valve as described above.

[0030] This invention utilizes a large valve needle with an elastic sealing element and a small valve port. The small valve needle is divided into a needle rod and a valve needle. When closed, the needle rod presses against the elastic sealing element to form a first-stage seal, and the valve needle inserts into the small valve port to form a second-stage seal. These two stages of sealing are arranged along the media path. This solves the problem of leakage and jamming caused by hard contact wear in traditional small valve needles. The media flows through a path from the lateral opening to the small valve port; that is, the sealing sequence is first the elastic seal and then the small valve port. This allows for graded pressure processing, reducing impact on the valve needle and further reducing wear. Simultaneously, the elastic seal, as the first stage, buffers the contact, avoiding direct wear from hard contact. Thus, the two-stage sealing (elastic contact seal and insertion seal) solves the problem of traditional hard contact, improving reliability and accuracy. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 A schematic diagram of an embodiment of the dual-valve needle electronic expansion valve provided by this utility model;

[0033] Figure 2 for Figure 1 A schematic diagram of an embodiment in which a small or medium-sized valve needle is inserted through a large valve needle;

[0034] Figure 3 for Figure 2 A schematic diagram of the structure of an embodiment of the central sealing ring platform;

[0035] Figure 4 for Figure 2 A schematic diagram of the structure of an embodiment of a small or medium-sized valve needle.

[0036] Explanation of icon numbers:

[0037] 10. Valve seat; 11. Large valve port;

[0038] 20. Connecting seat;

[0039] 30. Rotor assembly; 31. Limiting plate; 32. Lead screw;

[0040] 33. Bearings;

[0041] 40. Nuts;

[0042] 50. Small valve needle; 51. Needle shank; 52. Valve needle section; 53. Valve needle conical surface;

[0043] 60. Large valve needle; 61. Sealing ring platform; 61a. Small valve port; 61a1. Valve port chamfer; 61b. Upper surface; 61c. Mounting groove; 62. Lateral opening; 63. Elastic seal; 64. First-stage seal; 65. Second-stage seal;

[0044] 70. Elastic reset component;

[0045] 80. Abutment structure.

[0046] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0047] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0048] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0049] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0050] Traditional single-valve needle electronic expansion valves have gradually revealed their limitations when dealing with large flow regulation and precise control of small openings. Dual-valve needle electronic expansion valves have emerged to address this issue. Their core design concept is to decompose flow regulation into a two-stage control of "coarse adjustment + fine adjustment"—the outer valve needle is responsible for the main flow regulation under large stroke, while the inner valve needle compensates for the small opening range, thus taking into account both the wide flow range and the need for high-precision regulation.

[0051] In current dual-valve needle electronic expansion valves, during the low-flow regulation stage, the small valve needle and the small valve port are mainly sealed by abutting each other, and the flow rate is adjusted by the distance between them. However, the small valve needle and the small valve port are in hard contact to seal and stop. As a result, during the valve opening and closing process, the small valve needle and the small valve port are in constant contact, which will cause wear, leading to excessive internal leakage, reduced system efficiency, or even jamming and failure of the entire valve.

[0052] This invention proposes a dual-valve needle electronic expansion valve. It aims to solve problems such as wear, internal leakage, and even jamming caused by the hard contact sealing between the small valve needle and the small valve port in traditional dual-valve needle electronic expansion valves during low-flow regulation.

[0053] Please see Figures 1 to 4In one embodiment of this utility model, the dual-valve needle electronic expansion valve includes a large valve needle 60 and a small valve needle 50. The end of the large valve needle 60 is provided with a sealing ring platform 61, and the sealing ring platform 61 has a small valve port 61a. The periphery of the large valve needle 60 is provided with a lateral opening 62 communicating with the small valve port 61a. The sealing ring platform 61 is also provided with an elastic sealing element 63. The small valve needle 50 is axially movable and passes through the large valve needle 60. The small valve needle 50 includes a needle rod portion 51 and a valve needle portion 52 with a diameter smaller than that of the needle rod portion 51. When the small valve needle 50 is in the closed position, the needle rod portion 51 presses against the elastic sealing element 63 to form a first-stage seal 64, and the valve needle portion 52 is inserted into the small valve port 61a to form a second-stage seal 65. The first-stage seal 64 and the second-stage seal 65 are arranged sequentially along the path of the medium flowing through the lateral opening 62 to the small valve port 61a.

[0054] The technical solution of this utility model involves a large valve needle 60 equipped with an elastic sealing element 63 and a small valve port 61a. The small valve needle 50 is divided into a needle rod portion 51 and a valve needle portion 52. When closed, the needle rod portion 51 presses against the elastic sealing element 63 to form a first-stage seal 64, and the valve needle portion 52 inserts into the small valve port 61a to form a second-stage seal 65. These two stages of seals are arranged along the medium path. This solves the problem of leakage and jamming caused by hard contact wear in traditional small valve needles 50. Utilizing the deformation capability of the elastic sealing element 63, a buffer is provided when the small valve needle 50 contacts the small valve port 61a, avoiding wear or jamming caused by rigid collision. That is, the sealing sequence is elastic sealing first, followed by small valve port 61a, along the path of the medium flowing through the lateral opening 62. This graded pressure treatment reduces the impact on the valve needle portion 52, further reducing wear. Simultaneously, the elastic seal, as the first stage, buffers the contact, avoiding direct wear from hard contact. By sequentially setting two levels of seals (elastic seal + insertion seal) along the medium flow path, the reliability of the seal is improved and the risk of internal leakage is reduced.

[0055] The medium needs to pass through the side opening 62, the first-stage seal 64, and the second-stage seal 65 in sequence. The two seals form a pressure gradient, which further suppresses leakage. The elastic seal 63 (first stage) bears the main sealing pressure, and the small valve needle 50 is inserted into the small valve port 61a (second stage) as a backup seal. The two act sequentially along the medium flow path to form a double guarantee. The medium needs to overcome the deformation resistance of the elastic seal 63 and the gap seal between the small valve needle 50 and the small valve port 61a, which greatly reduces the probability of leakage.

[0056] In other words, this solution can solve the problem of wear on the contact surface and seal failure (internal leakage) caused by repeated opening and closing when the small valve needle 50 and the small valve port 61a are in hard contact. The first-stage seal 64 forms a seal by deformation and compression of an elastic material (such as rubber or polytetrafluoroethylene), reducing rigid contact friction and significantly reducing wear. Even if the first-stage elastic seal fails slightly due to long-term use, the seal of the second-stage small valve needle 50 inserted into the small valve port 61a can still maintain its sealing performance and extend the valve's life.

[0057] The elastic seal 63 absorbs impact energy when the small valve needle 50 actuates, preventing direct rigid collision between the valve needle part 52 and the small valve port 61a, thus reducing metal-to-metal contact wear. The elastic material of the first-stage seal 64 is replaceable or self-compensating for wear. The second-stage seal 65 experiences reduced wear rate due to lower contact pressure, and also solves the problem of metal particles easily falling off due to hard contact, which can aggravate damage to the sealing surface and even jam the valve needle. Moreover, the flexibility and self-lubricating properties of the elastic seal 63 can prevent metal-to-metal adhesion and reduce the risk of jamming.

[0058] Combination Figure 2 and Figure 3 Specifically, the upper surface 61b of the sealing ring platform 61 is provided with a mounting groove 61c. The elastic seal 63 is installed in the mounting groove 61c, and partially extends beyond the mounting groove 61c. The mounting groove 61c provides a mounting space for the elastic seal 63 to limit its radial displacement and prevent the elastic seal 63 from shifting due to medium pressure or vibration. The height of the elastic seal 63 extending beyond the mounting groove 61c ensures that it is in full contact with the small valve needle 50 in the closed state, avoiding seal failure due to installation errors. When not under pressure, the elastic seal 63 naturally protrudes from the mounting groove 61c. When the small valve needle 50 is closed, the seal is compressed to be flush with or slightly lower than the mounting groove 61c, forming a preload to compensate for microscopic unevenness of the sealing surface.

[0059] Specifically, the protruding portion of the elastic seal 63 is compressed when the small valve needle 50 is closed, with a deformation of up to 20%-30%, filling the microscopic gaps between the sealing surfaces and achieving zero leakage.

[0060] Specifically, the depth h of the mounting groove 61c is 0.1mm-0.5mm.

[0061] Specifically, the height H of the elastic seal 63 is 0.4mm-0.8mm.

[0062] Specifically, the deformation of the elastic seal 63 is 0.1mm-0.3mm, such as 0.15mm or 0.2mm, to provide pre-compression and compensate for assembly errors. Additionally, the mounting groove 61c has a chamfer to prevent sharp edges from scratching the seal and improve installation reliability.

[0063] Specifically, in order to improve the overall structure, reduce assembly steps, enhance sealing performance, reduce costs, and improve production efficiency, the sealing ring platform 61 is embedded in the large valve needle 60 and injection molded as a whole with the large valve needle 60. The sealing ring platform 61 is directly injection molded as a functional structure of the large valve needle 60, reducing the number of parts in the split design and reducing assembly complexity.

[0064] Furthermore, the sealing ring 61 is made of polyphenylene sulfide; or the sealing ring 61 is made of polyphenylene sulfide containing 10%-30% carbon fiber or glass fiber, which can reduce the friction coefficient between the small valve needle 50 and the sealing ring 61, reduce fretting wear, and extend service life.

[0065] In other embodiments, the sealing ring platform 61 and the large valve needle 60 are integrally injection molded; or integrally machined; or the sealing ring platform 61 is embedded in the large valve needle 60 and then welded to the large valve needle 60.

[0066] Specifically, the elastic seal 63 is a sealing ring, made of rubber (such as polyurethane rubber, silicone rubber, hydrogenated nitrile rubber, etc.) or plastic.

[0067] Reference Figure 3 and Figure 4 Furthermore, the inlet end of the small valve port 61a is provided with a valve port chamfer 61a1, and a valve needle cone surface 53 is formed at the connection between the valve needle part 52 and the needle rod part 51. When the small valve needle 50 is in the closed position, the valve needle cone surface 53 and the valve port chamfer 61a1 are in close contact to form a second-stage seal 65. On the one hand, the cone surface can better fit the chamfer, making it easier to achieve a tight seal and reduce leakage; on the other hand, the cooperation between the chamfer and the cone surface may reduce friction during opening and closing, because the cone surface can guide the valve needle to be correctly aligned, reducing lateral forces and thus reducing wear. This can extend the service life of the valve, especially in applications with frequent opening and closing.

[0068] Specifically, the radius of the valve port chamfer 61a1 ranges from 0.2mm to 1.0mm.

[0069] Specifically, the angle β between the valve needle cone surface 53 and the bottom surface of the needle rod portion 51, that is, the perpendicular line from the axial direction of the small valve port 61a, is 60°-70°.

[0070] Specifically, the first-stage seal 64 has a first sealing surface, and the second-stage seal 65 has a second sealing surface. The tangent of the first sealing surface and the tangent of the second sealing surface form an angle in space. The angle design allows the second-stage seal 65 to maintain effective contact when the first-stage elastic seal 63 deforms.

[0071] This solution is suitable for scenarios involving high-frequency start-up and shutdown and precise regulation of small flow rates (such as heat pump systems and precision refrigeration equipment), while also balancing large flow rate regulation with stability at small opening degrees.

[0072] Specifically, dual-needle valve structures are commonly found in applications requiring precise flow control, such as refrigeration systems, air conditioning systems, and heat pump systems. In these systems, valves need to handle both large and small flow rate regulation. This solution is suitable for all valves requiring coordinated flow control with dual-needle valves (or multi-stage valves) and facing wear or leakage issues during small flow rate regulation, and is particularly suitable for the following scenarios:

[0073] 1. Valves that need to accommodate both large-flow coarse adjustment and small-flow precision, such as: air conditioning / refrigeration systems: refrigerant flow staged control (e.g., heat pumps, low-temperature cold storage) or industrial fluid control, such as scenarios in the chemical and semiconductor industries where high precision of medium flow is required. By adding an elastic sealing element 63 to the large valve needle 60 in the existing dual-valve needle structure, a staged seal is formed, avoiding hard contact wear during the precision adjustment stage.

[0074] 2. For valves that involve frequent opening and closing (such as thermal management systems for new energy vehicles and electronic expansion valves for variable frequency air conditioners), the buffering effect of the elastic seal 63 can reduce impact wear under high-frequency operation and extend valve life. At the same time, the two-stage sealing structure ensures sealing reliability.

[0075] The main structure of the dual-valve needle electronic expansion valve consists of an electromagnetic drive module (stator coil), a transmission mechanism, and a valve body assembly.

[0076] In one embodiment, the dual-valve needle electronic expansion valve is configured with a nut 40 fixed and a lead screw 32 moving structure. That is, when the electromagnetic force drives the rotor to rotate, the nut 40 is fixed to the valve body, forcing the rotor itself to move up and down along the lead screw axis.

[0077] In one embodiment, the dual-valve needle electronic expansion valve is configured with a fixed lead screw 32 and a movable nut 40 structure. Compared with the previous solution, the rotor and stator coil will not shift in the radial gap during dynamic processes, that is, there will be no radial misalignment between the rotor and stator coil, which would reduce the electromagnetic driving force. Especially for dual-valve needles that require large stroke and large opening, the rotor only rotates around the axis (without axial movement), and the stator coil and rotor remain constant throughout the radial distance. This eliminates the magnetic field distortion caused by the vertical displacement of the rotor in the traditional solution, improves the attenuation of electromagnetic driving force, and ensures that a stable driving force can still be output even with a large stroke (such as 8-10mm).

[0078] Specifically, the valve seat 10 has a large valve port 11, and the connecting seat 20 is fixedly connected to the valve seat 10; the rotor assembly 30 includes a limiting plate 31 and a lead screw 32, the end of the lead screw 32 is fixed to the limiting plate 31, the lead screw 32 passes through the connecting seat 20, and the lead screw 32 is axially fixed and rotatably mounted on the connecting seat 20; the nut 40 passes through the connecting seat 20 and is threadedly engaged with the lead screw 32, and can move axially along the lead screw 32; the small valve needle 50 is fixedly connected to the nut 40; the large valve needle 60 is provided with The valve seat 10 has a small valve port 61a, and a small valve needle 50 is movably inserted through a large valve needle 60. An elastic reset member 70 is disposed in the valve seat 10. When the small valve needle 50 seals the small valve port 61a, the large valve needle 60 seals the large valve port 11 under the elastic force of the elastic reset member 70. When the lead screw 32 rotates, the nut 40 moves axially along the lead screw 32 and drives the small valve needle 50 to disengage from the small valve port 61a, and drives the large valve needle 60 to disengage from the large valve port 11 through the abutment structure 80.

[0079] The valve seat 10 has a medium inflow pipe interface on its side wall. The large valve needle 60 passes through the valve seat 10 and the connecting seat 20. In order to fix the axial coaxiality, there is a guide section with clearance fit between the outer wall of the large valve needle 60 and the valve seat 10 to ensure that the axial movement of the large valve needle 60 is free from wobble. The guide section is an inner hole provided in the valve seat 10 in the axial direction that has clearance fit with the outer wall of the large valve needle 60.

[0080] The stator coil is installed on the outer side of the housing above the valve seat 10. The stator coil corresponds to the rotor in the rotor assembly 30, eliminating rotor radial offset, stabilizing electromagnetic efficiency, and solving the problem of insufficient driving force of traditional double valve needles under large stroke.

[0081] To achieve axial fixation and rotatability of the lead screw 32 within the connecting seat 20, in this embodiment, the lead screw 32 and the connecting seat 20 are connected by a bearing 33. Specifically, the lead screw 32 has a bearing 33 limiting portion, the bearing 33 passes through the lead screw 32 and abuts against the bearing 33 limiting portion, the limiting plate 31 is welded to the end of the lead screw 32, and a bearing 33 pressure plate is also provided between the bearing 33 and the limiting plate 31, allowing the lead screw 32 to rotate freely but restricting axial movement.

[0082] In other solutions, two sets of angular contact ball bearings 33 (back-to-back installation) can be embedded in the connecting seat 20, with the lead screw 32 passing through the inner ring of the bearing 33 and pre-tightened by the lock nut 40 to achieve bidirectional axial positioning. Alternatively, a self-lubricating copper alloy bushing can be provided between the lead screw 32 and the connecting seat 20, with the end of the lead screw 32 axially locked by a shoulder and a retaining ring (such as an E-type retaining circlip), allowing the lead screw 32 to rotate freely but restricting axial movement. Alternatively, a ball spline lead screw 32 can be used, with the spline shaft engaging with the spline groove in the connecting seat 20, achieving pure rotational motion of the lead screw 32 (without axial displacement) through ball circulation.

[0083] This utility model also proposes a refrigeration device, which includes a dual-valve needle electronic expansion valve. The specific structure of the refrigeration device is as described in the above embodiments. Since this refrigeration device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0084] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A dual-valve needle electronic expansion valve, characterized in that, include: A large valve needle, the end of which is provided with a sealing ring platform, the sealing ring platform having a small valve port, the circumference of which is provided with a lateral opening communicating with the small valve port, and the sealing ring platform also being provided with an elastic sealing element; A small valve needle is axially movable and inserted inside the large valve needle. The small valve needle includes a needle shank portion and a valve needle portion with a diameter smaller than that of the needle shank portion. When the small valve needle is in the closed position, the needle rod part presses against the elastic sealing element to form a first-level seal, and the valve needle part is inserted into the small valve port to form a second-level seal; The first-stage seal and the second-stage seal are arranged sequentially along the path of the medium flowing through the lateral opening to the small valve port.

2. The dual-valve needle electronic expansion valve as described in claim 1, characterized in that, The upper surface of the sealing ring platform is provided with a mounting groove, and the elastic seal is installed in the mounting groove, with a portion extending beyond the mounting groove.

3. The dual-valve needle electronic expansion valve as described in claim 2, characterized in that, The depth of the mounting groove is 0.1mm-0.5mm.

4. The dual-valve needle electronic expansion valve as described in claim 3, characterized in that, The height of the elastic seal is 0.4mm-0.8mm.

5. The dual-valve needle electronic expansion valve as described in claim 2, characterized in that, The deformation of the elastic seal is 0.1mm-0.3mm.

6. The dual-valve needle electronic expansion valve as described in claim 1, characterized in that, The sealing ring is embedded in the large valve needle and is injection molded as a single unit with the large valve needle.

7. The dual-valve needle electronic expansion valve as described in claim 1, characterized in that, The sealing ring is made of polyphenylene sulfide; or the sealing ring is made of polyphenylene sulfide containing 10%-30% carbon fiber or glass fiber.

8. The dual-valve needle electronic expansion valve as described in claim 1, characterized in that, The inlet end of the small valve port is provided with a valve port chamfer, and the connection between the valve needle part and the needle rod part forms a valve needle conical surface. When the small valve needle is in the closed position, the valve needle conical surface and the valve port chamfer are in close contact to form a second-level seal.

9. The dual-valve needle electronic expansion valve as described in claim 8, characterized in that, The radius of the valve port chamfer is in the range of 0.2mm-1.0mm; and / or, the angle between the valve needle cone surface and the bottom surface of the needle rod is 60°-70°.

10. The dual-valve needle electronic expansion valve as described in claim 1, characterized in that, The first-stage seal has a first sealing surface, and the second-stage seal has a second sealing surface, wherein the tangent of the first sealing surface and the tangent of the second sealing surface form an angle in space.

11. The dual-valve needle electronic expansion valve as described in claim 1, characterized in that, The dual-valve needle electronic expansion valve also includes: Valve seat with a large valve port; The connecting seat is fixedly connected to the valve seat; A lead screw, which passes through the connecting seat, is connected to the connecting seat via a bearing, and is axially fixed and rotatably mounted on the connecting seat; The rotor assembly includes a limiting plate, and the end of the lead screw is fixed to the limiting plate; A nut is inserted through the connecting seat and threaded into the lead screw, and can move along the axial direction of the lead screw; A resilient reset element is disposed within the valve seat; When the small valve needle seals the small valve port, the elastic reset member causes the large valve needle to seal the large valve port. When the lead screw rotates, the nut moves along the axial direction of the lead screw and drives the small valve needle to disengage from the small valve port, and through the abutment structure, drives the large valve needle to disengage from the large valve port.

12. A refrigeration device, characterized in that, Includes the dual-valve needle electronic expansion valve as described in any one of claims 1 to 11.

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