An electronic expansion valve and an assembly method thereof

Abstract

The present invention relates to an electronic expansion valve and an assembly method thereof. The electronic expansion valve includes a valve seat, a nut component, a valve needle, a lead screw, and a connecting portion. The valve seat is provided with a valve port portion, and the valve needle is provided with an end sealing surface adapted to the valve port portion. The lead screw is in a limiting connection or a fixed connection with the valve needle, and a part of the lead screw is located inside the nut component and is in threaded cooperation with the nut component. The lead screw can drive the valve needle to perform an axial lifting movement to approach or move away from the valve port portion. The inner wall of the nut component is provided with a first stopping structure, and the valve needle or the lead screw is provided with a second stopping structure. When the first stopping structure and the second stopping structure abut against each other, a gap is left between the end sealing surface and the valve port portion. The nut component can move axially relative to the valve seat to adjust the gap, and the nut component can be fixed to the valve seat through the connecting portion. The flow rate of the electronic expansion valve in the fully closed state can be adjusted and set according to different requirements, which can ensure the flow rate accuracy, has good flexibility, can meet different requirements, and has a wide application range.

Description

Technical Field

[0001] The present invention relates to the technical field of valves, and particularly relates to an electronic expansion valve and an assembly method thereof. Background Art

[0002] An electronic expansion valve includes a valve seat, a nut component, a valve needle and a lead screw. Among them, the valve seat is provided with a valve port portion, the valve needle is adapted to the valve port portion, the valve seat and the nut component are relatively fixed, and the lead screw can rotate relative to the nut component and drive the valve needle to move axially along it to adjust the opening degree of the valve port portion.

[0003] When the valve needle of some electronic expansion valves moves to cooperate with the valve port portion to reach the fully closed state, the valve port portion is still in a flowing state, that is, there is still flow in the fully closed state. And the flow accuracy of such an electronic expansion valve in the fully closed state is difficult to guarantee, making it inapplicable to occasions with multiple requirements. Summary of the Invention

[0004] The purpose of the present invention is to provide an electronic expansion valve and an assembly method thereof. The flow rate of the electronic expansion valve in the fully closed state can be adjusted and set according to different requirements, the flow accuracy can be guaranteed, and it has good flexibility, can meet different requirements, and has a wide application range.

[0005] To solve the above technical problems, the present invention provides an electronic expansion valve, which includes a valve seat, a nut component, a valve needle, a lead screw and a connecting portion; the valve seat is provided with a valve port portion, and the valve needle is provided with an end sealing surface adapted to the valve port portion; the lead screw is in a limiting connection or a fixed connection with the valve needle, part of the lead screw is located inside the nut component, the lead screw is in a threaded fit with the nut component, and through the action of the threaded fit, the lead screw can drive the valve needle to perform an axial lifting movement to approach or move away from the valve port portion; the inner wall of the nut component is provided with a first stop structure, the first stop structure protrudes substantially radially towards the axis direction of the nut component, the valve needle or the lead screw is provided with a second stop structure, and when the first stop structure and the second stop structure are in contact, a gap is left between the end sealing surface and the valve port portion; the nut component can move axially relative to the valve seat to adjust the gap, and the nut component can be fixed to the valve seat through the connecting portion.

[0006] The present invention also provides an assembly method of an electronic expansion valve, which includes the following steps:

[0007] S1: Form a lead screw-valve needle assembly by limiting connection or fixed connection of the valve needle and the lead screw;

[0008] S2: Partially pass the lead screw through the nut component to be in threaded connection with the nut component;

[0009] S3: Connect and preliminarily fix the nut component and the valve seat;

[0010] S4: The lead screw rotates relative to the nut component and drives the valve needle to move axially to a position where the first stop structure cooperates with the second stop structure, so as to reach the fully closed state;

[0011] S5: In the fully closed state, measure the flow rate at the valve port, and adjust the position of the nut component relative to the valve seat according to the measurement result and the preset flow rate until the measurement result reaches the preset flow rate;

[0012] S6: Fix the nut component and the valve seat through the connecting part.

[0013] The technical effects of the present invention are as follows:

[0014] Through the setting of the two stop structures, the electronic expansion valve can achieve the purpose of having a flow rate even in the fully closed state. The overall structure is relatively simple, and through the cooperation of the two stop structures, the flow rate accuracy in the fully closed state can be ensured to meet the user's needs.

[0015] The nut component and the valve seat can move relative to each other along the axial direction of the nut component, and when they move relative to each other, the size of the above-mentioned gap can be adjusted. Specifically, according to the user's requirement for the flow rate of the electronic expansion valve in the fully closed state (i.e., the preset flow rate), the relative position of the nut component and the valve seat in the axial direction can be adjusted, and then the two can be fixed through the connecting part. In this way, different user needs can be met, with good flexibility and a wide application range. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of an electronic expansion valve provided by an embodiment of the present invention;

[0017] Figure 2 is a schematic structural diagram of the valve port and the end sealing surface in the fully closed state;

[0018] Figure 3 is a schematic structural diagram of the valve seat and the first connecting piece;

[0019] Figure 4 is a schematic structural diagram of the nut component and the second connecting piece;

[0020] Figure 5 is Figure 4 a cross-sectional view of;

[0021] Figures 6 - 7 is a schematic structural diagram of the valve needle and the lead screw;

[0022] Figure 8 is a schematic structural diagram of the assembly of the lead screw, the valve needle and the nut component;

[0023] Figure 9 is a schematic structural diagram of an electronic expansion valve before the nut component and the valve seat are assembled;

[0024] Figure 10 A cross-sectional view of the preliminary assembly of the nut component and the valve seat;

[0025] Figure 11 is a cross-sectional view after the electronic expansion valve is assembled;

[0026] Figure 12 is a flow chart of the assembly method of the nut component and the valve seat of the electronic expansion valve.

[0027] Appendix Figures 1 - 12 In the following, the reference numerals are explained as follows:

[0028] 1-valve seat, 11-valve port part;

[0029] 2-nut component, 21-annular protrusion;

[0030] 3-valve needle, 31-end sealing surface, 32-limit protrusion;

[0031] 4-screw rod;

[0032] 5-first stop structure;

[0033] 6-second stop structure;

[0034] 7-connection part, 71-first connection member, 711-mounting cylinder, 72-second connection member;

[0035] 8-clearance;

[0036] L1-first distance; L2-second distance; D1-diameter of the valve port part; D2-diameter of the end sealing surface. Detailed implementation manners

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] The embodiment of the present invention provides an electronic expansion valve, as Figure 1As shown in the figure, the electronic expansion valve includes a valve seat 1, a nut component 2, a valve needle 3, a lead screw 4, and a connecting portion 7. Among them, the valve seat 1 is provided with a valve port portion 11, the valve needle 3 is provided with an end sealing surface 31 adapted to the valve port portion 11, and the lead screw 4 is connected to the valve needle 3 in a limited or fixed manner. Herein, the fixed connection means that the lead screw 4 and the valve needle 3 are relatively fixed, and the limited connection means that the lead screw 4 and the valve needle 3 cannot move relative to each other in the axial direction, but relative rotation can occur between the two. Part of the lead screw 4 is located inside the nut component 2, and the lead screw 4 is in threaded engagement with the nut component 2. And through the action of the threaded engagement, the lead screw 4 can drive the valve needle 3 to perform axial lifting movement to approach or move away from the valve port portion 11, so as to adjust the opening degree of the valve port portion 11.

[0039] The inner wall of the nut component 2 is provided with a first stop structure 5, which protrudes substantially in the radial direction towards the axis direction of the nut component 2. The valve needle 3 or the lead screw 4 is provided with a second stop structure 6. When the lead screw 4 can drive the valve needle 3 to axially move until the two stop structures (the first stop structure 5 and the second stop structure 6) are in abutting fit, the distance between the end sealing surface 31 and the valve port portion 11 is the smallest, and the electronic expansion valve is in the fully closed state. And in the fully closed state, there is a gap 8 between the end sealing surface 31 and the valve port portion 11 (as Figure 2 shown), that is to say, the electronic expansion valve still has a flow rate in the fully closed state.

[0040] In this embodiment, through the setting of the two stop structures, the purpose that the electronic expansion valve also has a flow rate in the fully closed state can be achieved. The overall structure is relatively simple, and through the cooperation of the two stop structures, the flow rate accuracy in the fully closed state can be ensured to meet the user's requirements.

[0041] The nut component 2 and the valve seat 1 can move relative to each other along the axial direction of the nut component 2, and when they move relative to each other, they can adjust the size of the above-mentioned gap 8. Specifically, according to the user's requirement for the flow rate of the electronic expansion valve in the fully closed state (i.e., the preset flow rate), the relative position of the nut component 2 and the valve seat 1 in the axial direction can be adjusted, and then the two can be fixed through the connecting portion 7. In this way, different user requirements can be met, with good flexibility and a wide application range.

[0042] The embodiment of the present invention also provides an assembly method for an electronic expansion valve, as Figure 12 6]shown, the assembly method specifically includes the following steps:

[0043] S1: Connect the valve needle 3 and the lead screw 4 through a limited connection or a fixed connection to form a lead screw-valve needle assembly.

[0044] First, assemble the valve needle 3 and the lead screw 4 to form a lead screw valve needle assembly. The connection between the valve needle 3 and the lead screw 4 can be a limit connection or a fixed connection. Specifically, a fixed connection means that the lead screw 4 and the valve needle 3 are relatively fixed, and a limit connection means that the lead screw 4 and the valve needle 3 cannot move relative to each other in the axial direction, but they can rotate relative to each other.

[0045] S2: Pass part of the lead screw 4 through the nut component 2 to be threadedly connected to the nut component 2.

[0046] After assembling the valve needle 3 and the lead screw 4, pass part of the lead screw 4 through the nut component 2, and the lead screw 3 is threadedly connected to the nut component 2 (as shown in Figure 8 ). When they rotate relative to each other, the whole lead screw valve needle assembly can move axially along the nut component 2.

[0047] S3: Connect and preliminarily fix the nut component 2 and the valve seat 1.

[0048] After assembling the valve needle 3, the lead screw 4 and the nut component 2 as a whole, connect the nut component 2 and the valve seat 1 (as shown in Figure 9 ), and conduct preliminary fixation (as shown in Figure 10 ). At this time, the relative positions between the nut component 2 and the valve seat 1 can remain unchanged without external force. Specifically, the nut component 2 and the valve seat 1 can be preliminarily connected through the connecting portion 7, or they can be preliminarily connected through other structures provided separately. There is no specific limitation here.

[0049] S4: Rotate the lead screw relative to the nut component and drive the valve needle to move axially to the first stop structure to cooperate with the second stop structure to reach the fully closed state;

[0050] S5: In the fully closed state, measure the flow rate at the valve port part, and adjust the position of the nut component relative to the valve seat according to the measurement result and the preset flow rate until the measurement result reaches the preset flow rate;

[0051] In the fully closed state, there is still a gap 8 between the end sealing surface 31 and the valve port part 11. Simulate the use scenario, measure the flow rate of the gap 8 at the valve port part 11. During the measurement process, the relative positions of the nut component 2 and the valve seat 1 will not change. Then, adjust the relative positions of the nut component 2 and the valve seat 1 again according to the measurement result and the preset flow rate. When the measurement result reaches the preset flow rate, it means that the relative positions between the nut component 2 and the valve seat 1 can meet the requirements, and the adjustment ends.

[0052] S6: Fix the nut component 2 and the valve seat 1 through the connecting portion 7.

[0053] After the relative positions of the nut component 2 and the valve seat 1 are adjusted, they can be fixed through the connecting portion 7 (as shown inFigure 11 As shown in the figure, at this time, the electronic expansion valve has a fixed preset flow rate in the fully closed state. During later use, the relative positions of the nut component 2 and the valve seat 1 also remain unchanged.

[0054] Since during the assembly process, the flow rate in the fully closed state is measured and the relative positions of the nut component 2 and the valve seat 1 are adjusted according to the measurement results, the flow rate accuracy of the electronic expansion valve in the fully closed state can be guaranteed, and it has good flexibility, can meet different requirements, and has a wide range of applications.

[0055] Furthermore, the diameter D2 of the end sealing surface (referring to the diameter of the end sealing surface 31 at the valve port 11 when the electronic expansion valve is in the fully closed state) is not greater than the diameter D1 of the valve port. The axial distance between the first stop structure 5 and the valve port 11 is the first distance L1, and the axial distance between the second stop structure 6 and the end sealing surface 31 is the second distance L2. The first distance L1 is not less than the second distance L2. With such a setting, it can be ensured that there is still a gap 8 between the end sealing surface 31 and the valve port 11 in the fully closed state, and the electronic expansion valve still has a flow rate.

[0056] In the above embodiment, as Figure 3 shown, the connecting portion 7 includes a first connecting member 71 fixed to the valve seat 1. The first connecting member 71 is provided with a mounting cylinder 711 coaxially arranged with the valve port 11. The end of the nut component 2 is located inside the mounting cylinder 711, and the valve needle 3 can pass through the mounting cylinder 711 to cooperate with the valve port 11. Furthermore, as Figure 4 and Figure 5 shown, the connecting portion 7 may further include a second connecting member 72. The second connecting member 72 is fixed to the nut component 2 and can be sleeved outside the mounting cylinder 711 (as Figure 1 、 Figure 10 and Figure 11 shown).

[0057] In this embodiment, the connecting portion 7 may only be provided with the first connecting member 71. At this time, there is an interference fit between the inner wall of the mounting cylinder 711 and the outer wall of the end of the nut component 2. With such a setting, during the assembly process, when testing the flow rate in the fully closed state, the relative position between the mounting cylinder 711 and the nut component 2 can be guaranteed to be stable, and further the relative position between the nut component 2 and the valve seat 1 can be guaranteed to be stable, and the situation of position displacement can be avoided without setting other fixing components. After adjusting the relative position between the nut component 2 and the valve seat 1, to further ensure the installation stability, the first connecting member 71 and the nut component 2 can be further fixed, specifically, it can be fixed by setting other fixing structures or by welding or other methods.

[0058] When the connecting part 7 includes two connecting parts, namely the first connecting part 71 and the second connecting part 72, at this time, there is an interference fit between the inner wall of the mounting cylinder 711 and the outer wall of the end of the nut part 2, or there is an interference fit between the second connecting part 72 and the outer wall of the mounting cylinder 711. When testing the flow rate in the fully closed state, the relative position between the mounting cylinder 711 and the nut part 2 can be ensured to be stable, and further the relative position between the nut part 2 and the valve seat 1 can be ensured to be stable, and the situation of position displacement can be avoided without setting other fixing parts. And after adjusting the relative position between the nut part 2 and the valve seat 1, in order to further ensure the installation stability, the first connecting part 71 and the nut part 2 can be further fixed, or the second connecting part 72 and the valve seat 1 can be further fixed, or alternatively, the first connecting part 71 and the second connecting part 72 can be further fixed. Specifically, it can be fixed by welding or by setting other fixing structures.

[0059] That is to say, the connecting part 7 can be set to a structure including only the first connecting part 71, or can be set to a structure including the first connecting part 71 and the second connecting part 72, which can be specifically set according to the actual situation and is not specifically limited here.

[0060] In the above embodiment, the material of the nut part 2 is plastic, and the second connecting part 72 and the nut part 2 are integrally injection-molded. In this way, the processing technology can be simplified. The second connecting part 72 and the first connecting part 71 or the second connecting part 72 and the valve seat 1 can be fixed by welding.

[0061] During the assembly process of this electronic expansion valve, the preliminary connection between the nut part 2 and the valve seat 1 can be realized through the interference fit between the inner wall of the mounting cylinder 711 and the outer wall of the end of the nut part 2, or through the interference fit between the second connecting part 72 and the outer wall of the mounting cylinder 711, so that the relative position between the nut part 2 and the valve seat 1 remains temporarily stable, and the flow rate in the fully closed state can be tested. Then, the nut part 2 and the valve seat 1 are axially relatively moved by an external force (such as a hydraulic cylinder, etc.). Due to the setting of the interference fit, after the external force is withdrawn, the relative position between the nut part 2 and the valve seat 1 can still remain relatively stable. Until finally the measurement result reaches the preset flow rate, the nut part 2 and the valve seat 1 are fixed through the connecting part 7 (such as welding the first connecting part 71 and the second connecting part 72). At this time, the relative position between the nut part 2 and the valve seat 1 is stable and cannot be changed anymore, and the assembly is completed.

[0062] In the above embodiment, the specific structure of the second connecting part 72 is not limited, such as Figure 4As shown, it can be set as the structure of a cylinder body. One end inner wall of the cylinder body is fixed to the outer wall of the nut component 2, and the other end of the cylinder body is sleeved outside the installation cylinder 711. Alternatively, the second connecting member 72 can also be set as connecting claws circumferentially spaced along the outer wall of the nut component 2, and the inner walls of the connecting claws enclose an installation space, and the installation cylinder 711 can be located within this installation space.

[0063] In the above embodiment, for the above-mentioned second stop structure 6, the present embodiment provides the following two setting methods:

[0064] First, as Figure 6 shown, a limiting protrusion 32 is circumferentially provided on the outer wall of one end of the valve needle 3 facing the lead screw 4. The lower end surface of the limiting protrusion 32 forms the above-mentioned second stop structure 6. The axial distance from the lower end surface of the limiting protrusion 32 to the end sealing surface 31 is the second distance L2. When the lead screw 4 rotates relative to the nut component 2 and drives the valve needle 3 to move axially until the lower end surface of the limiting protrusion 32 abuts and cooperates with the first stop structure 5, the electronic expansion valve is in a fully closed state, and there is a gap 8 between the end sealing surface 31 and the valve port 11.

[0065] Second, as Figure 7 shown, the diameter of the valve needle 3 is smaller than that of the lead screw 4. The lower end surface of the lead screw 4 forms the above-mentioned second stop structure 6. The axial distance from the lower end surface of the lead screw 4 to the end sealing surface 31 is L2. When the lead screw 4 rotates relative to the nut component 2 and drives the valve needle 3 to move axially until the lower end surface of the lead screw 4 abuts and cooperates with the first stop structure 5, the electronic expansion valve is in a fully closed state, and there is a gap 8 between the end sealing surface 31 and the valve port 11.

[0066] Any combination of the above two setting methods of the second stop structure 6 is acceptable, and no specific limitation is made here.

[0067] When the second stop structure 6 is formed by the lower end surface of the limiting protrusion 32, the limiting protrusion 32 can be an annular structure circumferentially provided on the outer wall of one end of the valve needle 3 facing the lead screw 4. Of course, the limiting protrusion 32 can also be set as at least two protrusions circumferentially spaced along the outer peripheral wall of the valve needle 3, and no specific limitation is made here. The annular structure is convenient for processing and can ensure the cooperation stability of the two stop structures.

[0068] In the above embodiment, an annular protrusion 21 is circumferentially provided on the inner peripheral wall of one end of the nut component 2 facing the valve seat 1. The upper end surface of the annular protrusion 21 forms the above-mentioned first stop structure 5. That is to say, as Figure 5As shown, the nut component 2 includes a large-diameter section and a small-diameter section (the section with the annular protrusion 21) along its axial direction. Among them, the large-diameter section is arranged on the side of the small-diameter section away from the valve seat 1. A stepped structure is formed between the large-diameter section and the small-diameter section. The upper end surface of the small-diameter section (i.e., the upper end surface of the annular protrusion 21) forms the above-mentioned first stop structure 5. Of course, in this embodiment, no specific limitation is imposed on the first stop structure 5 provided in the nut component 2. For example, at least two protrusions can be arranged at intervals along the circumferential direction of the inner wall of the nut component 2. The arrangement of the annular protrusion 21 is convenient for processing and can ensure the cooperation stability of the two stop structures. In addition, the annular protrusion 21 is located at the end of the nut component 2 facing the valve seat 1 (such as Figure 5 as shown), or the annular protrusion 21 can be located inside the nut component 2 (that is, the inner diameter of the end of the nut component 2 is greater than the inner diameter of the annular protrusion 21). It can be specifically set according to the actual situation and no specific limitation is made here.

[0069] In the above embodiment, for the assembly method of the electronic expansion valve, before the above step S1, it further includes step S0:

[0070] Prepare the valve seat 1 so that the valve seat 1 includes a valve port part 11. A first connection interface part is machined on the side wall of the valve seat 1, and a second connection interface part is machined on the lower part of the valve seat 1;

[0071] Prepare the nut component 2 so that the nut component 2 is provided with a nut accommodation hole, and further includes an internal thread part and a first stop structure 5, and make the first stop structure 5 protrude substantially along the radial direction towards the axis of the nut component 2;

[0072] Prepare the screw rod 4-valve needle 3 assembly so that the screw rod 4-valve needle 3 assembly includes a screw rod 4 and a valve needle 3, and make the screw rod 4 fixedly connected or limitedly connected to the valve needle 3. The screw rod 4 is provided with an external thread part adapted to the internal thread part. A second stop part is provided on the screw rod 4 or the valve needle 3. Through the action of thread fit, the first stop part abuts against the second stop part, so that the screw rod 4-valve needle 3 assembly moves downward to the limit position, and a gap 8 is formed between the end sealing surface 31 of the valve needle 3 and the valve port part 11.

[0073] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. An electronic expansion valve, characterized in that, It includes a valve seat (1), a nut component (2), a valve needle (3), a lead screw (4) and a connecting portion (7); The valve seat (1) is provided with a valve port portion (11), and the valve needle (3) is provided with an end sealing surface (31) adapted to the valve port portion (11); The lead screw (4) is in a limiting connection or a fixed connection with the valve needle (3), a part of the lead screw (4) is located inside the nut component (2), the lead screw (4) is in threaded cooperation with the nut component (2), and through the action of the threaded cooperation, the lead screw (4) can drive the valve needle (3) to perform an axial lifting movement to approach or move away from the valve port portion (11); The inner wall of the nut component (2) is provided with a first stop structure (5), the first stop structure (5) protrudes substantially radially towards the axis direction of the nut component (2), and the valve needle (3) or the lead screw (4) is provided with a second stop structure (6). When the first stop structure (5) and the second stop structure (6) are in contact with each other, a gap (8) is left between the end sealing surface (31) and the valve port portion (11); The nut component (2) can move axially relative to the valve seat (1) to adjust the gap (8), and the nut component (2) can be fixed to the valve seat (1) through the connecting portion (7); The connecting portion (7) includes a first connecting member (71) fixed to the valve seat (1), the first connecting member (71) is provided with an installation cylinder (711) coaxially arranged with the valve port portion (11), the end of the nut component (2) is located inside the installation cylinder (711), and the valve needle (3) can pass through the installation cylinder (711) to cooperate with the valve port portion (11).

2. The electronic expansion valve according to claim 1, wherein, The diameter (D2) of the end sealing surface is not greater than the diameter (D1) of the valve port portion; The axial distance between the first stop structure (5) and the valve port portion (11) is a first distance (L1), the axial distance between the second stop structure (6) and the end sealing surface (31) is a second distance (L2), and the first distance (L1) is not less than the second distance (L2); The nut component (2) can move axially relative to the valve seat (1) to adjust the first distance (L1).

3. The electronic expansion valve according to claim 1, characterized in that, There is an interference fit between the inner wall of the installation cylinder (711) and the outer wall of the end of the nut component (2).

4. The electronic expansion valve according to claim 1, wherein, The connecting portion (7) further includes a second connecting member (72), the second connecting member (72) is fixed to the nut component (2) and can be sleeved outside the installation cylinder (711); There is an interference fit between the inner wall of the installation cylinder (711) and the outer wall of the end of the nut component (2), or there is an interference fit between the second connecting member (72) and the outer wall of the installation cylinder (711).

5. The electronic expansion valve according to claim 4, characterized in that, The first connecting member (71) and the second connecting member (72) are fixed by welding.

6. The electronic expansion valve according to claim 4 or 5, characterized in that, The nut component (2) is made of plastic material, the first connecting member (71) and the second connecting member (72) are both made of metal material, and the nut component (2) and the second connecting member (72) are integrally injection-molded.

7. The electronic expansion valve according to any one of claims 1-5, characterized in that, A limiting projection (32) is circumferentially arranged on the outer wall of the valve needle (3). The lead screw (4) can drive the valve needle (3) to axially move along it until the lower end surface of the limiting projection (32) abuts and cooperates with the first stop structure (5), and the lower end surface of the limiting projection (32) forms the second stop structure (6).

8. The electronic expansion valve according to claim 7, characterized in that, The limiting projection (32) is an annular structure circumferentially arranged on the outer wall of the valve needle (3).

9. The electronic expansion valve according to any one of claims 1-5, characterized in that, The diameter of the valve needle (3) is smaller than that of the lead screw (4), and the lower end surface of the lead screw (4) forms the second stop structure (6).

10. The electronic expansion valve according to any one of claims 1-5, characterized in that, An annular projection (21) is circumferentially arranged on the inner wall of the nut member (2), and the upper end surface of the annular projection (21) forms the first stop structure (5).

11. An assembly method of an electronic expansion valve, based on the electronic expansion valve according to any one of claims 1-10, characterized in that, The assembling method of the electronic expansion valve comprises the following steps: S1: Form a lead screw valve needle assembly by limiting connection or fixed connection of the valve needle and the lead screw; S2: Partially pass the lead screw through the nut member to be threadedly connected with the nut member; S3: Connect and preliminarily fix the nut member and the valve seat; S4: Rotate the lead screw relative to the nut member and drive the valve needle to axially move along it until the first stop structure and the second stop structure cooperate to reach the fully closed state; S5: Under the fully closed state, measure the flow rate at the valve port, and adjust the position of the nut member relative to the valve seat according to the measurement result and the preset flow rate until the measurement result reaches the preset flow rate; S6: Fix the nut member and the valve seat through the connecting part.

12. The assembling method of the electronic expansion valve according to claim 11, wherein, Before step S1, there is also step S0: Prepare the valve seat, make the valve seat include a valve port, machine a first connection interface part on the side wall of the valve seat, and machine a second connection interface part on the lower part of the valve seat; Prepare the nut member, make the nut member have a nut accommodation hole, and further include an internal thread part and a first stop part, and make the first stop part protrude substantially radially towards the axis direction of the nut member; Prepare the lead screw valve needle assembly, make the lead screw valve needle assembly include a lead screw and a valve needle, make the lead screw be fixedly connected or limit-connected with the valve needle, the lead screw is provided with an external thread part adapted to the internal thread part, the lead screw or the valve needle is provided with a second stop part, through the action of thread fit, make the first stop part and the second stop part abut against each other, make the lead screw valve needle assembly move downward to the limit position, and a gap is formed between the end sealing surface of the valve needle and the valve port.

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