CN110529606B

CN110529606B - Electronic expansion valve

Info

Publication number: CN110529606B
Application number: CN201810517510.4A
Authority: CN
Inventors: 不公告发明人
Original assignee: Zhejiang Sanhua Intelligent Controls Co Ltd
Current assignee: Zhejiang Sanhua Intelligent Controls Co Ltd
Priority date: 2018-05-25
Filing date: 2018-05-25
Publication date: 2022-04-29
Anticipated expiration: 2038-05-25
Also published as: CN110529606A

Abstract

The invention provides an electronic expansion valve, comprising: the valve seat is provided with a valve seat cavity and a valve port; a valve needle having an internal threaded portion, at least a portion of the valve needle being movably disposed in the valve seat cavity; the lead screw, the lead screw has external screw thread portion, and the lead screw can rotate along self axis, and the lead screw cooperatees through internal thread portion and external screw thread portion with the needle, and the valve needle is close to or keeps away from the valve port under the drive of lead screw. By applying the technical scheme of the invention, the electronic expansion structure can be simplified, and the production cost can be reduced.

Description

Electronic expansion valve

Technical Field

The invention relates to the technical field of refrigeration control, in particular to an electronic expansion valve.

Background

The electronic expansion valve structure, as shown in fig. 1, is composed of a driving part (coil 7, rotor 8) and a flow regulating part (nut 3, screw 4, housing, valve needle 5, valve seat 9, adapter, etc.). Specifically, the rotor 8 is connected to an input end of the speed reducer, and the lead screw 4 is connected to an output end of the speed reducer (the lead screw 4 can rotate together with the output end of the speed reducer, and a relative position of the lead screw 4 to the output end of the speed reducer in an axial direction thereof can be changed). The nut 3 is fixed on the valve seat 9 and is in threaded connection with the screw rod 4, and the valve needle 5 is fixedly connected with the screw rod 4. The following brief statement of the working principle of the product: the rotor 8 is driven by the coil 7 to rotate, the input shaft of the speed reducer is driven by the rotor to rotate, and the output end of the speed reducer rotates at a small rotating speed after the speed of the input shaft is reduced by the speed reducer. Under the action of the output end of the speed reducer, the screw rod 4 rotates. The screw rod 4 realizes axial movement through threaded fit with the nut 3. Under the action of the screw rod 4, the valve needle 5 is lifted axially to approach or be away from the valve port 6. Although the electronic expansion valve can achieve the purpose of adjusting the flow, the screw rod 4 can drive the valve needle 5 to move axially up and down only by means of the thread matching with the nut 3 during actuation, and the electronic expansion valve has a complex overall structure and high production cost.

Disclosure of Invention

The invention mainly aims to provide an electronic expansion valve which can simplify an electronic expansion structure and reduce production cost.

In order to achieve the above object, the present invention provides an electronic expansion valve comprising: the valve seat is provided with a valve seat cavity and a valve port; a valve needle having an internal threaded portion, at least a portion of the valve needle being movably disposed in the valve seat cavity; the lead screw, the lead screw has external screw thread portion, and the lead screw can rotate along self axis, and the lead screw cooperatees through internal thread portion and external screw thread portion with the needle, and the valve needle is close to or keeps away from the valve port under the drive of lead screw.

By applying the technical scheme of the invention, the valve needle of the electronic expansion valve is provided with an internal thread part, the screw rod is provided with an external thread part, and the screw rod is matched with the valve needle through the internal thread part and the external thread part. When the screw rod rotates, the valve needle in threaded fit with the screw rod can be close to or far away from the valve port. Because the screw rod is directly matched with the valve needle through the threads, a nut component mentioned in the background technology is eliminated, the integral structure of the electronic expansion valve is simplified, and the production cost can be reduced.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic diagram showing an internal structure of an electronic expansion valve in the prior art;

fig. 2 shows a schematic longitudinal sectional view of an embodiment of an electronic expansion valve according to the invention;

fig. 3 shows an enlarged schematic view of the electronic expansion valve of fig. 2 at a;

fig. 4 is a schematic longitudinal sectional view showing a partial structure of the electronic expansion valve of fig. 2;

fig. 5 is a schematic perspective view illustrating a support frame of the electronic expansion valve of fig. 2;

FIG. 6 is a longitudinal cross-sectional view of the support frame of FIG. 5;

fig. 7 is a perspective view illustrating a valve seat body of the electronic expansion valve of fig. 2;

FIG. 8 shows a longitudinal cross-sectional schematic view of the valve seat body of FIG. 7;

fig. 9 is a schematic perspective view of a sleeve of the electronic expansion valve of fig. 2;

FIG. 10 shows a longitudinal cross-sectional schematic view of the sleeve of FIG. 9;

fig. 11 shows a schematic perspective view of a valve needle of the electronic expansion valve of fig. 2; and

figure 12 shows a longitudinal cross-sectional schematic view of the valve needle of figure 11.

Wherein the figures include the following reference numerals:

1. a valve seat cavity; 2. an accommodating chamber; 10. a valve seat; 11. a valve seat body; 111. a second top wall; 112. a second side wall; 113. a second guide cylinder; 114. an annular groove; 12. a valve core seat; 121. a valve port; 20. a valve needle; 21. a valve needle body; 211. a second hole; 212. a threaded hole; 22. a sealing part; 30. a screw rod; 40. a support frame; 41. a first top wall; 411. a first hole; 412. a first guide cylinder; 42. a first side wall; 421. a groove; 50. a drive mechanism; 51. a rotor; 52. a coil; 60. a limiting structure; 70. a protrusion; 80. a sealing structure; 90. a sleeve; 91. a barrel portion; 92. an annular convex edge; 100. a housing; 200. a valve needle cavity.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

As shown in fig. 2 to 4, 11 and 12, in the present embodiment, the electronic expansion valve includes a valve seat 10, a valve needle 20, and a screw 30. The valve seat 10 has a valve seat chamber 1 and a valve port 121. The valve needle 20 has an internal thread, at least part of the valve needle 20 being movably arranged in the valve seat chamber 1. The screw rod 30 has an external thread part, the screw rod 30 can rotate along the axis of the screw rod 30, the screw rod 30 is matched with the valve needle 20 through the internal thread part and the external thread part, and the valve needle 20 is driven by the screw rod 30 to be close to or far away from the valve port 121.

With the technical solution of the present embodiment, the valve needle 20 of the electronic expansion valve has an internal thread portion, the screw 30 has an external thread portion, and the screw 30 and the valve needle 20 are matched through the internal thread portion and the external thread portion. When the screw rod 30 rotates, the valve needle 20 engaged with the screw thread can approach or separate from the valve port 121 to open and close the valve port, and adjust the refrigerant flow of the valve port 121. Because the screw rod 30 is directly matched with the valve needle 20 through threads, the nut component mentioned in the background technology is eliminated, and the parts are reduced, the assembly efficiency of the electronic expansion valve can be greatly improved, and meanwhile, the production cost is greatly reduced.

Note that, in the present embodiment, the position of the screw 30 in the axial direction is kept constant. The above-described position in the axial direction remains unchanged, which refers to two cases: in the first case, in the axial direction, the position of the screw 30 is completely fixed; in the second case, the screw 30 can move to a small extent in the axial direction due to tolerance influences. In the present embodiment, the needle 20 does not rotate. The non-rotation of the valve needle 20 refers to two conditions: in the first case, the needle 20 does not spin at all; in the second case, the needle 20 can be rotated to a small extent in the circumferential direction due to tolerance influences (a small rotation angle).

The screw rod 30 is in a slender rod shape, and the screw rod 30 may deflect when rotating, so that the valve needle 20 connected with the screw rod also deflects, and finally the valve needle 20 is easy to collide with the valve seat 10. In order to solve the above problem, as shown in fig. 2, 4 and 6, in the present embodiment, the electronic expansion valve further includes a support frame 40, the support frame 40 is fixedly connected to the valve seat 10, and the support frame 40 is provided with a first guide portion, which provides a guide function for the screw 30. The first guide portion can keep the axis of the screw rod 30 at a predetermined position, thereby preventing the screw rod 30 from deflecting during rotation, and finally solving the problem that the valve needle 20 is easy to collide with the valve seat 10.

As shown in fig. 2 to 6, in the present embodiment, the support bracket 40 includes a first top wall 41 and a first side wall 42, at least another portion of the valve needle 20 is located inside the first side wall 42, the first guiding portion is a first guiding cylinder 412 which is disposed on the first top wall 41 and extends downward, and the screw 30 penetrates through the first guiding cylinder 412 and is engaged with the valve needle 20. Specifically, since the support bracket 40 is fixed to the valve seat 10, the axis of the first guide cylinder 412 of the support bracket 40 is fixed. Because the screw rod 30 is arranged in the first guide cylinder 412 in a penetrating manner, the outer wall of the screw rod 30 is matched with the inner wall of the first guide cylinder 412, so that the axis of the screw rod 30 can be fixed. Therefore, the screw 30 does not deflect during rotation.

As shown in fig. 2 to 6, in the present embodiment, the support frame 40 is fixedly connected to the valve seat 10, one of the support frame 40 and the valve needle 20 is provided with a groove 421, the other of the support frame 40 and the valve needle 20 is provided with a protrusion 70, and a side wall of the protrusion 70 is in abutting fit with a groove wall of the groove 421. Specifically, in the present embodiment, the internal thread portion of the needle 20 is engaged with the external thread portion of the screw 30. The screw 30 is capable of rotating on its own axis, and the position in the axial direction remains unchanged. The needle 20 is movable in the axial direction and is not able to spin. When the screw rod 30 rotates, the valve needle 20 has a tendency to rotate under the driving of the screw rod 30, and at this time, the side wall of the protrusion 70 between the valve needle 20 and the support frame 40 will be abutted by the groove wall of the groove 421, so that the valve needle 20 cannot rotate. However, the valve needle 20 can move in the axial direction by the engagement of the internal thread portion and the external thread portion, thereby opening and closing the valve port. The structure is simple and easy to process. It should be noted that the groove 421 and the protrusion 70 together form the position limiting structure 60 to prevent the valve needle 20 from rotating.

As shown in fig. 2 to 6, fig. 11 and fig. 12, in the present embodiment, the support bracket 40 includes a first top wall 41 and a first side wall 42, a portion of the valve needle 20 is located inside the first side wall 42, a first hole 411 is formed in the first top wall 41, the screw rod 30 penetrates through the first hole 411 and is engaged with the valve needle 20, a groove 421 is formed in the bottom of the first side wall 42 and extends upward, a second hole 211 is formed in the side wall of the valve needle 20, and the protrusion 70 is a pin inserted into the second hole 211. The structure is simple and easy to process. Preferably, in this embodiment, the supporting frame 40 may be integrally formed by drawing, and the first guide cylinder 412 is formed by a flanging process. The support bracket 40 is press-fitted into the upper end portion of the valve seat 10 and fixedly installed by spot welding.

In this embodiment, the valve seat 10 is of an integrally formed structure, and/or the valve needle 20 is of an integrally formed structure, and/or the support 40 is of an integrally formed structure. The structure is simple, the processing is convenient, and the production efficiency is high. Specifically, the valve seat 10 may be integrally formed from a punch, a cold-heading, or a draw.

The valve needle 20 is in a long cylinder shape, the valve needle 20 is driven by the screw rod 30 to move axially, and slight deflection may occur in the screw rod 30, so that slight deflection may occur in the valve needle 20, and finally the valve needle 20 is easily collided with the valve seat 10. In order to solve the above problem, as shown in fig. 2 to 4, 7 and 8, in the present embodiment, a second guide portion is provided on the valve seat 10, and the second guide portion provides a guiding function to the valve needle 20. The second guide portion can maintain the axis of the valve needle 20 at a predetermined position, thereby preventing the valve needle 20 from deflecting during movement, and finally solving the problem that the valve needle 20 is easily collided with the valve seat 10.

As shown in fig. 2 to 4, 7 and 8, in the present embodiment, the valve seat 10 includes a valve seat body 11 and a valve core seat 12, the valve seat body 11 is integrally stretch-formed, an opening is provided at the bottom of the valve seat body 11, the valve core seat 12 is provided at the opening, the valve port 121 is provided at the valve core seat 12, a space surrounded by the valve seat body 11 and the valve core seat 12 forms a valve seat cavity 1, the valve seat body 11 includes a second top wall 111 and a second side wall 112, the second guide portion is a second guide cylinder 113 that is provided at the second top wall 111 and extends downward, the valve needle 20 penetrates into the valve seat cavity 1 from the second guide cylinder 113, and the bottom of the second side wall 112 forms an opening. In the present embodiment, the second guide cylinder 113 is an integral structure with the second top wall 111, and preferably, the second guide cylinder 113 is formed by a flanging process. Above-mentioned simple structure, processing is convenient, need not set up solitary guide cylinder, has improved production efficiency on the one hand, and on the other hand needn't open the mould again, has reduced manufacturing cost. It should be noted that, in this embodiment, the valve seat body 11 is integrally formed by stretching, and the above structure makes the valve seat body 11 easy to process and low in cost. Further, in the present embodiment, the needle 20 is press-fitted into the second guide cylinder 113 by a flip-chip method.

As shown in fig. 2 to 4 and 8, in the present embodiment, the second top wall 111 is provided with an annular groove 114, and the seal structure 80 is provided between the valve needle 20 and the annular groove 114. Specifically, a first interface and a second interface are arranged on the valve seat 10, the first interface is communicated with the valve port 121, a valve needle cavity 200 communicated with the valve port 121 is arranged in the valve needle, a sealing structure 80 is arranged between the valve seat 10 and the valve needle 20, and an anti-friction structure is arranged between the sealing structure 80 and the valve needle 20. The sealing structure 80 can prevent the first port and the second port from communicating with each other through the gap between the valve seat 10 and the valve needle 20, and prevent the interior of the valve seat 10 from communicating with the outside, so as to effectively isolate the transmission of the pressure difference between the upper and lower sides of the valve needle 20, and ensure that the valve needle 20 can be abutted against the valve port 121 under the action of the pressure difference.

Since the valve needle 20 moves up and down with respect to the valve seat 10 when moving in its axial direction, the seal structure 80 provided therebetween is easily worn over time, so that the sealing property is deteriorated. In order to solve the above problem, as shown in fig. 3 and 4, an anti-friction structure is provided between the seal structure 80 and the valve needle 20. The above structure can reduce the wear of the seal structure 80, thereby ensuring the sealing performance of the seal structure 80.

As shown in fig. 2 to 4, in the present embodiment, the electronic expansion valve further includes: the bottom of the shell 100 is positioned in the annular groove 114 and fixedly connected with the valve seat 10, the shell 100 is provided with a containing cavity 2, and the screw rod 30 is positioned in the containing cavity 2. The structure enables the lead screw 30, the support frame 40 and other precise structures to be contained in the containing cavity 2, so that the service life of the electronic expansion valve is prolonged.

It should be noted that if the accommodating chamber 2 is not communicated with the valve needle chamber 200, when the valve needle 20 abuts against the valve port 121 and the refrigerant enters the valve needle chamber 200 from the first interface (the interface of the standpipe), the pressure of the valve needle chamber 200 is much higher than that of the accommodating chamber 2, so that the valve needle 20 will be subjected to an upward differential pressure, which may cause the valve needle 20 to be far away from the valve port 121, and thus the valve needle 20 cannot be maintained at the closing position (the position where the valve needle 20 abuts against the valve port 121). At this point, only a large actuation force ensures that the needle 20 remains in the closed position. In order to avoid an increase in the driving force, in the first embodiment, the accommodation chamber 2 communicates with the valve needle chamber 200. The above structure makes the pressure of the valve needle cavity 200 close to the pressure of the accommodating cavity 2 when the valve needle 20 abuts against the valve port 121 and the refrigerant enters the valve needle cavity 200 from the first port, so that the upward differential pressure applied to the valve needle 20 will be greatly reduced, and it is not necessary to increase the driving force to ensure that the valve needle 20 is kept at the closing position.

As shown in fig. 2, in the present embodiment, the accommodating chamber 2 communicates with the valve needle chamber 200 through a gap between the internal thread portion and the external thread portion. The structure is simple and easy to process.

As shown in fig. 2 to 4, 9 and 10, in the present embodiment, a sleeve 90 is provided on the valve seat 10, the sleeve 90 includes a cylindrical body 91 and an annular flange 92 provided on an inner wall of the cylindrical body 91, an accommodation space is formed between a lower surface of the annular flange 92, the inner wall of the sleeve 90 and an upper surface of the valve seat 10, and the seal structure 80 is provided in the accommodation space. The structure is simple, and the processing and the assembly are easy. Note that, in the present embodiment, the sleeve 90 is press-fitted into the step of the upper end portion of the valve seat 10, and is fixed to the step of the valve seat 10 by spot welding.

As shown in fig. 2, in the present embodiment, the valve needle 20 includes a valve needle body 21 and a sealing portion 22 disposed at the bottom of the valve needle body 21, the valve needle body 21 is provided with a threaded hole 212 engaged with the screw rod 30, the size of the sealing portion 22 is larger than the diameter of the valve port 121, and the outer diameter of the valve needle body 21 is equal to the diameter of the valve port 121. Specifically, the first port (standpipe port) is formed through the valve needle cavity 200, and when the valve needle 20 is located at the closing position and the refrigerant enters the valve needle cavity 200 from the first port, the valve needle 20 is blocked at the valve port 121 by the downward differential pressure and the downward driving force of the driving mechanism 50, and is maintained at the closing position. The differential pressure force is formed by the action of the pressure and the area difference between the sectional area of the needle body 21 and the sectional area of the valve port 121. Since the outer diameter of the needle body 21 is equal to the diameter of the valve port 121, the differential pressure is zero, and therefore, the above structure does not require a downward urging force to be applied to the core assembly by a spring, and therefore, even if the diameter of the valve port 121 becomes large, the driving force does not need to be increased accordingly.

In addition, when the refrigerant enters the valve seat 10 from the second port (cross-connecting port), the valve needle 20 is subjected to an upward differential pressure and a downward driving force, so that the valve needle 20 is blocked at the valve port 121 and is kept at the closed position. The differential pressure force is formed by the action of the pressure and the area difference between the sectional area of the needle body 21 and the sectional area of the valve port 121. Since the outer diameter of the needle body 21 is equal to the diameter of the valve port 121, the differential pressure force is zero. Since the differential pressure is zero, the need for driving force is greatly reduced.

As shown in fig. 2, in the present embodiment, the electronic expansion valve further includes: the driving mechanism 50 includes a rotor 51 and a coil 52, the rotor 51 is fixedly connected with the lead screw 30, and the rotor 51 drives the lead screw 30 to rotate through the coil 52. The structure is simple and easy to realize. Since the electronic expansion valve of the valve port 121 with a large diameter in this embodiment has a small demand for driving force, the coil of the driving mechanism 50 does not need to be designed in a large scale, thereby greatly reducing the volume.

As shown in fig. 2, a coupling frame connected between the rotor 51 and the lead screw 30 is provided in the housing 100, and the rotor 51 and the coupling frame are integrally formed. The screw 30 is fixed to the rotor 51 by a link.

The operation of the electronic expansion valve is described in detail as follows:

under the excitation of the coil 52 fitted around the outer periphery of the housing 100, the rotor 51 rotates to drive the lead screw 30 to follow the rotation, and the lead screw 30 rotates only and does not operate in the axial direction. Due to the screwing action of the external thread portion of the screw rod 30 and the internal thread portion of the valve needle 20, the screw rod 30 drives the valve needle 20 to move in the axial direction. The needle 20 is lifted and lowered only in the axial direction without rotating, so that the sealing portion 22 of the needle 20 is gradually separated from the valve port 121, and when the pin fixed to the needle 20 abuts against the groove top wall of the recess 421 of the holder 40, the distance of the sealing portion 22 of the needle 20 from the valve port 121 is maximized, and at this time, the flow rate of the refrigerant flowing through the valve port 121 is maximized. When the rotor 51 is reversely rotated by the excitation of the coil 52, the needle 20 can be moved downward in the axial direction by the screwing action of the external thread portion of the screw 30 and the internal thread portion of the needle 20. At this time, the seal portion 22 of the needle 20 gradually approaches the valve port 121, and when the pin fixed to the needle 20 relatively approaches the lower end portion of the recessed groove 421 of the support frame 40, the seal portion 22 abuts against the valve port 121.

The steps for assembling the electronic expansion valve of the present embodiment will be briefly described as follows:

the method comprises the following steps: a10 valve seat body 11 is integrally formed, then corresponding step size is obtained through simple turning, and a first connecting pipe is welded and fixed at a first interface of the valve seat body 11;

step two: a20 press-fitting the valve needle 20 into the second guide cylinder 113 on the valve seat body 11 in an inverted manner;

step three: a30 welding and fixing the valve core seat 12 and the second connecting pipe and then welding and fixing the valve core seat and the lower end of the valve seat body 11;

step four: a40 fitting a pin into the second bore 211 of the valve needle 20 (ensuring that there is one second bore 211);

step five: a50, mounting the sealing structure 80 on the upper end step part of the valve seat body 11, then press-fitting the sealing structure into the sleeve 90, and fixing the sleeve 90 and the upper end step part of the valve seat body 11 by spot welding;

step six: a60 press-fitting the support 40 into the step part of the sleeve 90 and welding it;

step seven: a70 is fitted into the rotor 51, and the housing 100 is welded to the valve seat 10.

It should be noted that the steps other than A10-A30 can be changed in the installation order.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electronic expansion valve, comprising:

a valve seat (10) having a valve seat chamber (1) and a valve port (121);

a valve needle (20), the valve needle (20) having an internal thread, at least part of the valve needle (20) being movably arranged in the valve seat cavity (1);

the screw rod (30), the screw rod (30) has an external thread part, the screw rod (30) can rotate along the axis of the screw rod, the screw rod (30) is matched with the valve needle (20) through the internal thread part and the external thread part, and the valve needle (20) is driven by the screw rod (30) to be close to or far away from the valve port (121)

Support frame (40), with valve seat (10) fixed connection, support frame (40) are equipped with first guide part, first guide part is right lead screw (30) provide the guide effect, support frame (40) with valve seat (10) fixed connection, support frame (40) with one in needle (20) is provided with recess (421), support frame (40) with another in needle (20) is provided with arch (70), the lateral wall of arch (70) with the cell wall butt cooperation of recess (421).

2. An electronic expansion valve according to claim 1, wherein the support frame (40) comprises a first top wall (41) and a first side wall (42), at least another part of the valve needle (20) being located inside the first side wall (42), the first guide part being a first guide cylinder (412) provided on the first top wall (41) and extending downwards, the screw (30) passing out of the first guide cylinder (412) and engaging with the valve needle (20).

3. An electronic expansion valve according to claim 1, wherein the support frame (40) comprises a first top wall (41) and a first side wall (42), at least another part of the valve needle (20) is located inside the first side wall (42), a first hole (411) is provided in the first top wall (41), the screw (30) penetrates out from the first hole (411) and is engaged with the valve needle (20), the groove (421) is provided at the bottom of the first side wall (42) and extends upward, a second hole (211) is provided in the side wall of the valve needle (20), and the protrusion (70) is a pin inserted into the second hole (211).

4. An electronic expansion valve according to claim 1, wherein the valve seat (10) is of integrally formed construction, and/or the valve needle (20) is of integrally formed construction, and/or the support frame (40) is of integrally formed construction.

5. An electronic expansion valve according to claim 1, wherein a second guiding portion is provided on the valve seat (10), the second guiding portion providing a guiding action for the valve needle (20).

6. An electronic expansion valve according to claim 5, wherein the valve seat (10) comprises a valve seat body (11) and a valve core seat (12), the valve seat body (11) is integrally formed by stretching, an opening is arranged at the bottom of the valve seat body (11), the valve core seat (12) is arranged at the opening, the valve port (121) is arranged on the valve core seat (12), the space enclosed by the valve seat body (11) and the valve core seat (12) forms the valve seat cavity (1), the valve seat body (11) comprises a second top wall (111) and a second side wall (112), the second guide part is a second guide cylinder (113) which is arranged on the second top wall (111) and extends downwards, the valve needle (20) penetrates into the valve seat cavity (1) from the second guide cylinder (113), and the bottom of the second side wall (112) forms the opening.

7. An electronic expansion valve according to claim 6, wherein an annular groove (114) is provided in the second top wall (111), and a sealing structure (80) is provided between the valve needle (20) and the annular groove (114).

8. The electronic expansion valve of claim 7, further comprising:

the bottom of shell (100) is located in annular groove (114) and with valve seat (10) fixed connection, it holds chamber (2) to have in shell (100), lead screw (30) are located hold chamber (2).

9. An electronic expansion valve according to claim 1, wherein a sealing structure (80) is arranged between the valve seat (10) and the valve needle (20).

10. An electronic expansion valve according to claim 8, wherein a sleeve (90) is arranged on the valve seat (10), the sleeve (90) comprises a cylindrical body (91) and an annular convex edge (92) arranged on the inner wall of the cylindrical body (91), an accommodating space is formed between the lower surface of the annular convex edge (92), the inner wall of the sleeve (90) and the upper surface of the valve seat (10), and the sealing structure (80) is arranged in the accommodating space.

11. The electronic expansion valve according to claim 1, wherein the valve needle (20) comprises a valve needle body (21) and a sealing portion (22) disposed at a bottom of the valve needle body (21), a threaded hole (212) engaged with the screw rod (30) is disposed on the valve needle body (21), a thread structure in the threaded hole (212) forms the internal thread portion, the sealing portion (22) has a size larger than a diameter of the valve port (121), and an outer diameter of the valve needle body (21) is equal to the diameter of the valve port (121).

12. The electronic expansion valve of claim 1, further comprising:

the driving mechanism (50) comprises a rotor (51) and a coil (52), the rotor (51) is fixedly connected with the screw rod (30), and the rotor (51) drives the screw rod (30) to rotate through the coil (52).