CN111623126A

CN111623126A - Electronic expansion valve

Info

Publication number: CN111623126A
Application number: CN201910153395.1A
Authority: CN
Inventors: 龙江军; 邸志强; 马小红
Original assignee: Zhejiang DunAn Hetian Metal Co Ltd
Current assignee: Zhejiang DunAn Hetian Metal Co Ltd
Priority date: 2019-02-28
Filing date: 2019-02-28
Publication date: 2020-09-04

Abstract

The invention provides an electronic expansion valve, comprising: a valve body; the rotor is rotatably arranged in the valve body; the fixed seat is fixedly arranged in the valve body; the screw rod is arranged in the valve body, penetrates through the fixed seat and is in threaded connection with the rotor, and the rotor is used for driving the screw rod to move axially; and the rolling part is arranged between the rotor and the fixed seat. Through the technical scheme provided by the application, the problems of complex structure and easy abrasion in the prior art can be solved.

Description

Electronic expansion valve

Technical Field

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

Background

As shown in fig. 1, an electronic expansion valve generally comprises a rotor 1, a mandrel 2, a nut seat 3, a needle assembly 4, a limit spring 5, and the like, wherein the mandrel 2 is connected to the rotor 1, the mandrel 2 is connected to the nut seat 3 by a screw, and the needle assembly 4 is connected to the mandrel 2. The electronic expansion valve drives the mandrel 2 to rotate and make the mandrel move axially through the rotor 1, and then the mandrel 2 drives the valve needle component 4 to rotate and make the valve needle component move axially, so that the purposes of plugging and opening the valve port are achieved. However, the electronic expansion valve with the structure has the problems of complex structure and easy abrasion.

Disclosure of Invention

The invention provides an electronic expansion valve, which aims to solve the problems of complex structure and easy abrasion in the prior art.

The invention provides an electronic expansion valve, comprising: a valve body; the rotor is rotatably arranged in the valve body; the fixed seat is fixedly arranged in the valve body; the screw rod is arranged in the valve body, penetrates through the fixed seat and is in threaded connection with the rotor, and the rotor is used for driving the screw rod to move axially; and the rolling part is arranged between the rotor and the fixed seat.

Furthermore, the rolling part comprises a bearing, an outer ring of the bearing is connected with the rotor, and an inner ring of the bearing is connected with the fixed seat.

Furthermore, a first boss is arranged on the outer wall of the fixing seat, the inner ring of the bearing is abutted against the first boss, the outer ring of the bearing is abutted against the inner wall of the rotor, and the first boss is matched with the rotor to limit the displacement of the bearing.

Furthermore, the fixing seat is provided with a through hole, the screw rod is provided with a screw thread section and a limiting section, the screw thread section of the screw rod is in threaded connection with the rotor, the limiting section is located in the through hole, a rotation stopping structure is arranged between the through hole and the limiting section, and the rotation stopping structure is used for limiting the screw rod to rotate relative to the fixing seat.

Furthermore, the rotation stopping structure comprises a second boss and a rotation stopping groove, the second boss is arranged on the side wall of the limiting section, the rotation stopping groove is arranged on the inner wall of the through hole and corresponds to the second boss, the second boss is located in the rotation stopping groove, and the second boss and the rotation stopping groove are matched to limit the screw to rotate relative to the fixing seat.

Further, the electronic expansion valve further includes: the valve needle assembly is arranged in the valve body, and one end of the screw rod is connected with the valve needle assembly so as to drive the valve needle assembly to move axially through the screw rod.

Further, the valve body still includes: a sleeve; the valve seat is provided with a valve cavity and a mounting hole communicated with the valve cavity, the valve needle assembly is movably arranged in the mounting hole and the valve cavity, and the fixing seat is arranged in the mounting hole and fixedly connected with the valve seat.

Further, clearance fit is formed between the valve needle assembly and the mounting hole and/or between the valve needle assembly and the valve cavity.

Further, the valve seat comprises a seat body and a valve core which are detachably connected, the seat body is provided with a mounting hole, and the valve core is provided with a valve cavity.

Further, the valve needle assembly comprises: the first end of the valve needle faces the valve port, and the second end of the valve needle is connected with the screw rod; the pre-tightening spring is arranged between the valve needle and the screw rod and used for providing pre-tightening force for the valve needle.

Furthermore, the second end of the valve needle is provided with a first hole section and a second hole section which are arranged in a stepped mode, the aperture of the first hole section is larger than that of the second hole section, the second hole section is arranged close to the first end of the valve needle, the pre-tightening spring is arranged in the second hole section, one end of the screw rod is located in the first hole section, the diameter of the screw rod located in the first hole section is larger than that of the second hole section, and the end face of the screw rod located in the first hole section and the stepped surface of the valve needle axially form a movable gap.

Further, the valve needle assembly further comprises: and the pressing sleeve is arranged at the second end of the valve needle and is used for limiting the screw to withdraw from the first hole section.

Furthermore, the valve seat is provided with an exhaust hole which is arranged at the bottom of the mounting hole, one end of the exhaust hole is communicated with the mounting hole, the other end of the exhaust hole is communicated with the valve cavity, and the axis of the exhaust hole is not coincident with the axis of the mounting hole.

Further, the rotor includes rotor core and magnet, rotor core and rotor fixed connection, and the rotor core has relative first end and the second end that sets up, and the first end of rotor core is provided with the internal thread, and the screw rod is provided with the external screw thread, and the external screw thread of screw rod and the internal thread phase-match of rotor core, the outer lane of bearing is connected with the inner wall that the rotor core second was held.

Further, the top of the valve body is provided with a third boss, the third boss corresponds to the screw rod, and the third boss is used for limiting the screw rod to continuously move upwards.

By applying the technical scheme of the invention, the electronic expansion valve comprises a valve body, a rotor, a fixed seat, a screw and a rolling piece. Wherein, the rotor rotationally sets up in the valve body, and the fixing base is fixed to be set up in the valve body. Through passing the screw rod fixing base and with rotor threaded connection, utilize the rotor can drive the screw rod and carry out axial displacement, adopt above-mentioned structure, can simplify the structure of device. And, through setting up the rolling member between rotor and fixing base, can reduce the wearing and tearing between the part, extension device life to can reduce the noise that produces because of wearing and tearing.

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 of an electronic expansion valve according to the prior art;

fig. 2 is a schematic structural diagram of an electronic expansion valve according to an embodiment of the present invention.

Wherein the figures include the following reference numerals:

1. a rotor; 2. a mandrel; 3. a nut seat; 4. a valve needle assembly; 5. a limiting spring;

10. a valve body; 11. a sleeve; 12. a valve seat; 12a, a valve cavity; 12b, an exhaust hole; 13. a third boss;

20. a rotor;

30. a fixed seat; 31. a first boss;

40. a screw; 41. a second boss;

50. a rolling member;

60. a valve needle assembly; 61. a valve needle; 62. pre-tightening the spring; 63. and (5) pressing the sleeve.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 2, an embodiment of the present invention provides an electronic expansion valve, which includes a valve body 10, a rotor 20, a fixing seat 30, a screw 40, and a rolling member 50. Wherein, rotor 20 rotationally sets up in valve body 10, and fixing base 30 is fixed to be set up in valve body 10, and screw rod 40 sets up in valve body 10, and screw rod 40 passes fixing base 30 and with rotor 20 threaded connection, and rotor 20 is used for driving screw rod 40 axial displacement. The rolling element 50 is arranged between the rotor 20 and the fixed seat 30, so that the abrasion of the device can be reduced, the use precision of the device is improved, and the service life of the device is prolonged. Specifically, in the present embodiment, the rotor 20 only rotates in the valve body 10, and does not move axially, and the rotor 20 is rotated to drive the screw 40 to move axially, so that the volume of the device can be reduced, the structure of the device can be simplified, and the manufacturing cost of the device can be reduced.

By applying the electronic expansion valve provided by the embodiment, the rotor 20 is arranged in the valve body 10, the screw 40 passes through the fixed seat 30 and is in threaded connection with the rotor 20, and the rotor 20 is used for driving the screw 40 to axially move. Also, by providing the rolling member 50 between the rotor 20 and the holder 30, it is possible to reduce abrasion between components, to extend the life span of the device, and to reduce noise generated due to abrasion.

Specifically, the rolling element 50 includes a bearing, an outer ring of the bearing is connected to the rotor 20, and an inner ring of the bearing is connected to the fixing base 30. By adopting the structure, when the rotor 20 drives the screw 40 to move axially, the inner ring of the bearing is fixed on the outer wall of the fixed seat 30, so that the outer ring of the bearing rotates relative to the inner ring, and the purpose of reducing the abrasion of the device is achieved.

Specifically, be provided with first boss 31 on the outer wall of fixing base 30, the inner circle and the first boss 31 looks butt of bearing, and the outer lane of bearing and the inner wall looks butt of rotor 20 utilize first boss 31 and rotor 20 to cooperate in order to restrict the displacement of bearing to make the bearing can not carry out axial displacement relative to fixing base 30, can promote device's stability.

Specifically, fixing base 30 has the through-hole, and screw rod 40 has screw thread section and spacing section, and screw thread section and the 20 threaded connection of rotor of screw rod 40, spacing section are located the through-hole. And, the through-hole has the structure of splining between spacing section, and the structure of splining is used for restricting the relative fixing base 30 rotation of screw rod 40. Through set up between screw rod 40 and fixing base 30 and only rotate the structure, and fixing base 30 is fixed to be set up in the valve body, when rotor 20 drive screw rod 40 carries out axial displacement, can guarantee that screw rod 40 only carries out axial displacement, can not take place to rotate relative fixing base 30, so can further reduce the wearing and tearing of device.

Specifically, the rotation stopping structure includes a second boss 41 and a rotation stopping groove, wherein the second boss 41 is disposed on the side wall of the limiting section, the rotation stopping groove is disposed on the inner wall of the through hole corresponding to the second boss 41, the second boss 41 is located in the rotation stopping groove, and the second boss 41 and the rotation stopping groove are matched to limit the rotation of the screw 40 relative to the fixing seat 30. Specifically, in the present embodiment, the second boss 41 is circumferentially disposed on the sidewall of the screw 40, the cross section of the second boss 41 is square, and the rotation stopping groove is disposed in a square shape corresponding to the second boss 41.

In this embodiment, the electronic expansion valve further includes a valve needle assembly 60, the valve needle assembly 60 is disposed in the valve body 10, and specifically, one end of the screw 40 is connected to the valve needle assembly 60, so as to drive the valve needle assembly 60 to move axially through the screw 40, thereby achieving the purpose of blocking and opening the valve port.

Specifically, the valve body 10 further includes a sleeve 11 and a valve seat 12. Wherein the valve seat 12 is partially located in the sleeve 11, the valve seat 12 has a valve cavity 12a and a mounting hole communicated with the valve cavity 12a, the needle assembly 60 is movably disposed in the mounting hole and the valve cavity 12a, and the fixing seat 30 is disposed in the mounting hole and fixedly connected with the valve seat 12.

In this embodiment, there is a clearance fit between the valve needle assembly 60 and the mounting hole and/or between the valve needle assembly 60 and the valve cavity 12 a. With the above structure, when the screw 40 drives the valve needle assembly 60 to move axially, the valve needle assembly 60 can be guided through the mounting hole and/or the valve cavity 12 a. Compared with the mode of guiding the mandrel by using the nut seat in the prior art, the guiding mode can improve the coaxiality of the valve needle assembly 60 and the valve port, and further improve the precision of opening and closing the valve of the device. Further, the valve needle assembly 60 is directly guided by the valve seat 12, and the device can be simplified in structure while improving the device accuracy.

Specifically, the valve seat 12 includes a seat body and a valve core that are detachably connected, the seat body has a mounting hole, and the valve core has a valve cavity 12 a. Wherein, the valve needle assembly 60 can be guided by the mounting hole on the seat body and the valve cavity 12a on the valve core at the same time, so that the coaxiality of the valve needle assembly 60 and the valve port can be further promoted.

Specifically, the needle assembly 60 includes a needle 61 and a preloaded spring 62. The first end of the valve needle 61 is arranged towards the valve port, the second end of the valve needle 61 is connected with the screw 40, the pre-tightening spring 62 is arranged between the valve needle 61 and the screw 40, and the pre-tightening spring 62 is used for providing pre-tightening force for the valve needle 61. When the valve needle 61 abuts against the valve port, the biasing spring 62 can reduce the impact force between the valve needle 61 and the valve port, and thus can protect the valve needle 61 and the valve port.

Wherein, the second end of needle 61 has first hole section and the second hole section of ladder setting, the aperture of first hole section is greater than the aperture of second hole section, the first end setting that the second hole section is close to needle 61, pretension spring 62 sets up in the second hole section, the one end of screw rod is located first hole section, and the diameter that is located first hole section of screw rod 40 is greater than the aperture of second hole section, so that screw rod 40 can not get into the second hole section, and, the terminal surface that is located first hole section of screw rod 40 and the ladder face of needle 61 have along the clearance of the activity of axial setting. Specifically, the number of valve opening pulses of the device can be controlled by adjusting the clearance between the end surface of the screw 40 located in the first bore section and the stepped surface of the valve needle 61. In the present embodiment, the end surface of the screw 40 located in the first hole section is an annular boss which is integrally formed with the screw 40, and the first hole section and the second hole section of the valve needle 61 are also integrally formed. By adopting the integrated molding mode, the precision of the circular boss of the screw 40 and the first hole section of the valve needle 61 can be controlled, and the pulse precision of the device is further ensured. Specifically, the dimensional error of the clearance between the end surface of the screw 40 located in the first bore section and the stepped surface of the valve needle 61 is not more than 0.02mm, and the dimensional error is converted into 3 pulses with pulse precision. With the structure, the valve opening pulse of the device can be controlled through one-time assembly of the screw 40 and the valve needle 61, and the pulse precision of the device can be improved. And, the screw 40 and the valve needle 61 are in linear pulse contact, so that the abrasion of the device can be further reduced, and the pulse precision of the device is further ensured.

Specifically, the needle assembly 60 further includes a pressing sleeve 63, the pressing sleeve 63 is disposed at the second end of the needle 61, and the pressing sleeve 63 is used for limiting the screw 40 from withdrawing from the first bore section. Specifically, in the present embodiment, the end of the screw 40 has a protruding edge structure along the outer wall, and the pressing sleeve 63 is press-fitted into the first bore section of the valve needle 61 by interference fit, so that the pressing sleeve 63 cooperates with the protruding edge structure on the screw 40 to limit the displacement of the screw 40 in the valve needle 61.

Specifically, the valve seat 12 is provided with an exhaust hole 12b, the exhaust hole 12b is arranged at the bottom of the mounting hole, one end of the exhaust hole 12b is communicated with the mounting hole, the other end of the exhaust hole 12b is communicated with the valve cavity 12a, and the axis of the exhaust hole 12b is not coincident with the axis of the mounting hole. Wherein, can set up one or more exhaust hole 12b according to actual demand, can make the pressure between valve pocket 12a and the sleeve pipe 11 inside realize quick balance through setting up exhaust hole 12b, and then can play the guard action to the device, avoid causing the damage because of the too big device that causes of the pressure differential of valve pocket 12a and sleeve pipe 11 inside.

Specifically, rotor 20 includes rotor core and magnet, and wherein, rotor core and rotor 20 fixed connection, rotor core have relative first end and the second end that sets up, and rotor core's first end is provided with the internal thread, and screw rod 40 is provided with the external screw thread, and screw rod 40's external screw thread and rotor core's internal thread phase-match, the outer lane of bearing is connected with the inner wall of rotor core second end. Wherein, the rotor core both can with rotor 20 integrated into one piece, can reduce the manufacturing cost of device, the rotor core can also be made split type, so be convenient for the maintenance and the maintenance in device later stage.

Specifically, the top of the valve body 10 is provided with a third boss 13, the third boss 13 is arranged corresponding to the screw 40, and the third boss 13 is used for limiting the screw 40 to move upwards continuously. When the rotor 20 drives the screw 40 to move upwards, and the top end of the screw 40 contacts with the third boss 13, the third boss 13 can limit the screw 40 to prevent the screw 40 from moving upwards.

In other embodiments, when the rotor 20 drives the screw 40 to move upward, when the pressing sleeve 63 abuts against the end surface of the fixed seat 30 close to the needle assembly 60, the effect of limiting the screw 40 to move upward can be achieved.

Specifically, the device that this embodiment provided compares and to prior art can reduce the volume of device, in this embodiment, can set up the aperture of valve port to be more than or equal to 0.2mm to, and, the size specification of the pipe fitting with valve port intercommunication also can reduce correspondingly, and in this embodiment, the external diameter of the pipe fitting with valve port intercommunication is 3mm, and the wall thickness is 0.5mm, and the specific size of pipe fitting can be adjusted according to actual conditions.

Compared with the prior art, the device provided by the embodiment has the following beneficial effects:

(1) by providing a bearing between the fixed base 30 and the rotor 20, the outer ring of the bearing is connected to the rotor 20, the inner ring of the bearing is connected to the fixed base, and the rotor 20 drives the screw 40 to move axially, thereby reducing wear of the device.

(2) Through set up between screw rod 40 and fixing base 30 and spline the structure, can guarantee that screw rod 40 when carrying out axial displacement, can not take place to rotate relative to fixing base 30, and then can further reduce the wearing and tearing of device.

(3) When the rotor 20 drives the screw 40 to move upwards, the top end of the screw 40 is contacted with the third boss 13; or, when the pressing sleeve 63 abuts against the end surface of the fixed seat 30 close to the valve needle assembly 60, the axial stop of the device can be realized, the screw 40 is prevented from moving upwards, and the structure of the device can be simplified.

(4) By arranging clearance fit between the valve needle assembly 60 and the mounting hole and/or between the valve needle assembly 60 and the valve cavity 12a, the valve needle assembly 60 is guided by the mounting hole and/or the valve cavity 12a, the coaxiality of the valve needle assembly 60 and the valve port can be improved, the valve opening and closing precision of the device can be improved, and the structure of the device is simplified.

(5) The valve-opening pulse of the device can be controlled by adjusting the gap between the end surface of the screw 40 located in the first hole section and the stepped surface of the valve needle 61, and the valve-opening pulse of the device can be controlled by one-time assembly of the screw 40 and the valve needle 61, so that the pulse precision of the device can be improved. In addition, the screw 40 and the valve needle 61 are in linear pulse contact, so that the abrasion of the device can be further reduced, and the pulse precision of the device can be further ensured.

(6) The exhaust hole 12b can be arranged to realize rapid balance of pressure between the valve cavity 12a and the interior of the sleeve 11, so that the device can be protected, and damage to the device due to overlarge pressure difference between the valve cavity 12a and the interior of the sleeve 11 can be avoided.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of not making a reverse description, these orientation words do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be considered as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

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 body (10);

a rotor (20) rotatably disposed within the valve body (10);

the fixing seat (30) is fixedly arranged in the valve body (10);

the screw rod (40) is arranged in the valve body (10), the screw rod (40) penetrates through the fixed seat (30) and is in threaded connection with the rotor (20), and the rotor (20) is used for driving the screw rod (40) to move axially;

a rolling member (50) disposed between the rotor (20) and the holder (30).

2. An electronic expansion valve according to claim 1, wherein the rolling elements (50) comprise bearings, the outer ring of which is connected to the rotor (20) and the inner ring of which is connected to the holder (30).

3. An electronic expansion valve according to claim 2, wherein the outer wall of the fixed seat (30) is provided with a first boss (31), the inner ring of the bearing abuts against the first boss (31), the outer ring of the bearing abuts against the inner wall of the rotor (20), and the first boss (31) cooperates with the rotor (20) to limit the displacement of the bearing.

4. The electronic expansion valve according to claim 1, wherein the fixing base (30) has a through hole, the screw (40) has a threaded section and a limiting section, the threaded section of the screw (40) is in threaded connection with the rotor (20), the limiting section is located in the through hole, and a rotation stopping structure is provided between the through hole and the limiting section, and the rotation stopping structure is used for limiting the rotation of the screw (40) relative to the fixing base (30).

5. An electronic expansion valve according to claim 4, wherein the rotation stopping structure comprises a second boss (41) and a rotation stopping groove, the second boss (41) is disposed on the side wall of the limiting section, the rotation stopping groove is disposed on the inner wall of the through hole corresponding to the second boss (41), the second boss (41) is located in the rotation stopping groove, and the second boss (41) cooperates with the rotation stopping groove to limit the rotation of the screw (40) relative to the fixing seat (30).

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

the valve needle assembly (60) is arranged in the valve body (10), and one end of the screw rod (40) is connected with the valve needle assembly (60) so as to drive the valve needle assembly (60) to move axially through the screw rod (40).

7. An electronic expansion valve according to claim 6, wherein the valve body (10) further comprises:

a sleeve (11);

the valve seat (12), the valve seat (12) is located in the sleeve (11) partially, the valve seat (12) is provided with a valve cavity (12a) and a mounting hole communicated with the valve cavity (12a), the valve needle assembly (60) is movably arranged in the mounting hole and the valve cavity (12a), and the fixing seat (30) is arranged in the mounting hole and fixedly connected with the valve seat (12).

8. Electronic expansion valve according to claim 7, wherein there is a clearance fit between the valve needle assembly (60) and the mounting hole and/or between the valve needle assembly (60) and the valve chamber (12 a).

9. The electronic expansion valve according to claim 8, wherein the valve seat (12) comprises a seat body and a valve core which are detachably connected, the seat body having the mounting hole, and the valve core having the valve chamber (12 a).

10. An electronic expansion valve according to claim 6, wherein the valve needle assembly (60) comprises:

a valve needle (61), a first end of the valve needle (61) is arranged towards the valve port, and a second end of the valve needle (61) is connected with the screw rod (40);

the pre-tightening spring (62) is arranged between the valve needle (61) and the screw rod (40), and the pre-tightening spring (62) is used for providing pre-tightening force for the valve needle (61).

11. An electronic expansion valve according to claim 10, wherein the second end of the valve needle (61) has a first hole section and a second hole section arranged in a step, the first hole section has a larger hole diameter than the second hole section, the second hole section is arranged near the first end of the valve needle (61), the pre-tightening spring (62) is arranged in the second hole section, one end of the screw (40) is located in the first hole section, the diameter of the screw (40) located in the first hole section is larger than the hole diameter of the second hole section, and the end surface of the screw (40) located in the first hole section and the step surface of the valve needle (61) have a movable gap in the axial direction.

12. An electronic expansion valve according to claim 11, wherein the valve needle assembly (60) further comprises:

a pressure sleeve (63) disposed at a second end of the valve needle (61), the pressure sleeve (63) for limiting withdrawal of the screw (40) from the first bore section.

13. The electronic expansion valve according to claim 7, wherein the valve seat (12) is provided with a vent hole (12b), the vent hole (12b) is arranged at the bottom of the mounting hole, one end of the vent hole (12b) is communicated with the mounting hole, the other end of the vent hole (12b) is communicated with the valve cavity (12a), and the axis of the vent hole (12b) is not coincident with the axis of the mounting hole.

14. An electronic expansion valve according to claim 2, wherein the rotor (20) comprises a rotor core and a magnet, the rotor core is fixedly connected with the rotor (20), the rotor core has a first end and a second end which are oppositely arranged, the first end of the rotor core is provided with an internal thread, the screw (40) is provided with an external thread, the external thread of the screw (40) matches the internal thread of the rotor core, and the outer ring of the bearing is connected with the inner wall of the second end of the rotor core.

15. An electronic expansion valve according to claim 1, wherein a third boss (13) is provided on top of the valve body (10), the third boss (13) being provided in correspondence with the screw (40), the third boss (13) being adapted to restrict the screw (40) from continuing to move upwards.