CN108758058B

CN108758058B - Rotor assembly, assembling method and electronic expansion valve with same

Info

Publication number: CN108758058B
Application number: CN201810582309.4A
Authority: CN
Inventors: 许鸣飞; 杨国灿; 王少锋
Original assignee: Jiangsu Huayang Intelligent Equipment Co ltd
Current assignee: Jiangsu Huayang Intelligent Equipment Co ltd
Priority date: 2018-06-07
Filing date: 2018-06-07
Publication date: 2021-06-11
Anticipated expiration: 2038-06-07
Also published as: CN108758058A

Abstract

The invention discloses a rotor assembly, an assembly method and an electronic expansion valve with the same, wherein the rotor assembly comprises a rotor magnetic ring, the rotor magnetic ring is formed into a hollow column with one open end, and the other end of the rotor magnetic ring is provided with a channel which is through along the axial direction of the rotor magnetic ring; the screw rod shaft is inserted in the channel along the axial direction of the channel, one end of the screw rod shaft extends out of the open end of the rotor magnetic ring and is provided with an elongated slot extending along the axial direction of the rotor magnetic ring, and the other end of the screw rod shaft extends out of the channel; one end of the spring guide rail is embedded in the long groove, and the other end of the spring guide rail spirally surrounds the outer wall surface of the screw shaft towards the other end along the axial direction of the screw shaft; and the fixing piece is welded and connected with at least one part of the screw rod shaft so as to press one end of the spring guide rail in the long groove. The rotor assembly has the advantages of simple structure, easiness in manufacturing, reliable performance, cost reduction and the like.

Description

Rotor assembly, assembling method and electronic expansion valve with same

Technical Field

The present invention relates to a rotor assembly, a method of assembling the rotor assembly, and an electronic expansion valve having the rotor assembly, and more particularly, to a rotor assembly, a method of assembling the rotor assembly, and an electronic expansion valve having the rotor assembly, which are simple in structure and easy to manufacture, and which are used in an air conditioner, a refrigerator, or the like.

Background

The existing electronic expansion valve installed on refrigerators such as air conditioners, refrigerators and the like can adjust the fluid flow of a refrigerant, generally comprises a valve body with a valve chamber and a valve seat and a cylindrical shell fixed on the upper part of the valve body, a rotor is installed in the shell, a stator is installed outside the shell, the rotor in the electronic expansion valve comprises a screw shaft, the upper end part of the screw shaft is provided with a small long groove, the screw shaft is also provided with an annular groove which is annularly arranged along the peripheral surface of the screw shaft, the annular groove is close to the bottom of the small long groove, a spring guide rail is installed on the screw shaft, the upper limiting end of the spring guide rail is embedded into the small long groove, an elastic snap ring is arranged in the annular groove, the upper limiting end of the spring guide rail can be fastened through the elastic snap ring, and the elastic snap ring can not be clamped into the annular groove due, if the position size is too large, a gap is left between the upper limiting end of the spring guide rail and the bottom of the small long groove, when the electronic expansion valve works, the spring guide rail can axially move along the small long groove to influence the limiting precision of the rotor, so that the performance of the valve is influenced, and the electronic expansion valve has the defects of low finished product qualification rate, high cost and the like.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art.

Therefore, the invention provides a rotor assembly which has the advantages of simple structure, easiness in manufacturing and the like.

The invention also provides an assembly method of the rotor assembly, which uses laser welding to avoid the change and influence of large current on the magnetic performance of the rotor magnetic ring when argon arc welding, plasma welding, resistance welding and the like are used for welding.

The invention also provides an electronic expansion valve which is low in manufacturing cost and stable in performance.

A rotor assembly according to an embodiment of the first aspect of the invention, comprising: the rotor magnetic ring is formed into a hollow column shape with one open end, and the other end of the rotor magnetic ring is provided with a channel which is through along the axial direction of the rotor magnetic ring; the screw rod shaft is inserted into the channel along the axial direction of the channel, an annular groove is not formed in the outer peripheral surface of the screw rod shaft, one end of the screw rod shaft extends out of the open end of the rotor magnetic ring and is provided with a long groove extending along the axial direction of the rotor magnetic ring, and the other end of the screw rod shaft extends out of the channel; one end of the spring guide rail is embedded in the long groove, and the other end of the spring guide rail spirally surrounds the outer wall surface of the screw shaft towards the other end along the axial direction of the screw shaft; a fixing member welded to at least a portion of the screw shaft to compress one end of the spring guide within the elongated slot.

According to the rotor assembly provided by the embodiment of the invention, one end of the spring guide rail is embedded into the long groove, one end of the spring guide rail is pressed tightly through the fixing piece, the fixing piece and the screw shaft are fixed through welding, a high-position-precision annular groove does not need to be processed on the outer peripheral surface of the screw shaft, the spring guide rail is prevented from generating clearance movement after being fixed in the long groove, and the rotor assembly has the advantages of simple and reliable structure, easiness in manufacturing, stable performance of a finished product and the like.

According to one embodiment of the invention, the fixing element is fixedly connected to the screw shaft by laser welding.

According to one embodiment of the invention, the fixing element is formed as a snap ring.

According to one embodiment of the invention, the fixture is connected to the outer circumference of the screw shaft by circumferential welding.

According to one embodiment of the invention, the fixture is connected to the outer circumference of the screw shaft by a plurality of spot welds spaced circumferentially.

According to one embodiment of the present invention, the cross-section of the snap ring is formed in a rectangular shape.

According to one embodiment of the invention, the snap ring is formed as a stainless steel wire.

A method of assembling a rotor assembly according to an embodiment of the second aspect of the present invention includes: s1, sleeving a spring guide rail on the screw rod shaft and transversely embedding one end of the spring guide rail into an elongated slot of the screw rod shaft; s2, sleeving a fixing piece on the screw rod shaft and enabling the fixing piece to press one end of the spring guide rail; and S3, welding the junction of the fixing piece and the outer peripheral surface of the screw rod shaft by laser.

According to an embodiment of the invention, in step S3, the boundary between the snap ring and the outer peripheral surface of the screw shaft is circumferentially welded along the outer periphery of the screw shaft.

According to an embodiment of the invention, in step S3, the boundary between the elastic clamping ring and the outer peripheral surface of the screw shaft is welded at intervals along the outer periphery of the screw shaft.

An electronic expansion valve according to an embodiment of the third aspect of the present invention includes the rotor assembly according to the above-described embodiment.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a longitudinal sectional view of an electronic expansion valve according to the related art;

FIG. 2 is an enlarged view of area A of FIG. 1;

FIG. 3 is a longitudinal sectional view of a rotor assembly according to an embodiment of the present invention;

FIG. 4 is a front view of a stationary member of a rotor assembly according to an embodiment of the present invention;

fig. 5 is a sectional view of a stationary member of a rotor assembly according to an embodiment of the present invention;

FIG. 6 is a profile view of one end of a screw shaft of a rotor assembly according to an embodiment of the present invention;

FIG. 7 is a cross-sectional view of one end of a screw shaft of a rotor assembly according to an embodiment of the present invention;

FIG. 8 is an assembled partial cross-sectional view of a stationary member and a spring guide of a rotor assembly according to an embodiment of the present invention;

FIG. 9 is a schematic view of the assembly of the stationary member and the spring guide of the rotor assembly according to an embodiment of the present invention;

fig. 10 is a flowchart of a method of assembling a rotor assembly according to an embodiment of the present invention.

Reference numerals:

a rotor assembly 100;

a rotor magnetic ring 10; a channel 11;

a screw shaft 20; an elongated slot 21; a screw rod 22; a shaft 23; a balance aperture 24; an inner cavity 25; an externally threaded portion 26;

a spring guide 30; a fixing member 40;

a valve needle 50; a transverse aperture 51;

a slip ring 60; a compression spring 70; a smooth pad 80; a limit retainer ring 90;

an electronic expansion valve 1';

a valve body 2; a liquid inlet pipe 2 a; a liquid outlet pipe 2 b; a valve chamber 2 c; a valve seat 2 d; a flange mounting plate 2 e; a guide nut fixing portion 2g for fixing the guide nut,

a lead nut 3; a female screw portion 3 a;

a rotor 4; a spring guide 4 a; a slip ring 4 b; an elastic snap ring 4 c; a shaft 4 d; a spacer 4 e; a valve needle 4 f; a compression coil spring 4 g; a valve port 4 h; a limit retainer ring 4 j; a screw rod 4 k; a rotor magnetic ring 4 l; an external thread portion 4 m;

a housing 5; a support frame 5 a; a stopper rod 5 b; a bottomed cylinder 5 c;

a stator 6; a yoke 6 a; a coil bobbin 6 b; a stator coil 6 c; a yoke 6 d; unsaturated resin 6 e;

a wire 7; and a terminal 7 a.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The present invention was invented by the inventors based on the following facts.

Fig. 1 and 2 show an electronic expansion valve 1 'in the prior art, wherein fig. 1 is a longitudinal sectional view of the electronic expansion valve 1', and fig. 2 is an enlarged view of a region a in fig. 1.

As shown in fig. 1 and 2, the valve body 2 has a valve chamber 2c and a guide nut fixing portion 2g, a liquid inlet pipe 2a and a liquid outlet pipe 2b for introducing and discharging a fluid such as a refrigerant are provided in the valve chamber 2c, and a valve seat 2d is disposed in the valve chamber 2c, and the valve seat 2d is brought into contact with and separated from a valve port 4h formed at the tip of a needle 4f to control the flow rate.

A pilot nut fixing portion 2g located above a valve chamber 2c fixes a valve seat 2d and a pilot nut 3, a female screw portion 3a is provided on the inner periphery of the pilot nut 3, a lead screw 4k and a shaft 4d are manufactured separately and then are fitted by interference fit to form a lead screw shaft, a male screw portion 4m formed on the outer periphery of the lead screw 4k is screwed to the female screw portion 3a, and a screw sub-feeding mechanism is constituted by the female screw portion 3a and the male screw portion 4 m. The valve needle 4f is installed in the lower end part of the screw rod 4k, the valve needle 4f can slide, the valve needle 4f is pressed downwards through a compression spiral spring 4g which is installed in an inner cavity of the lower end part of the screw rod 4k in a compressed mode, in order to increase the flexibility of the compression spiral spring 4g rotating along the spring center, a gasket 4e is installed between the end face of the compression spiral spring 4g and the bottom of the inner cavity of the lower end part of the screw rod, in order to limit the valve needle 4f to be pushed out of the inner cavity of the lower end part of the screw rod 4k by the compression spiral spring 4g, and a limiting retainer.

The shell 5 fixed on the upper part of the valve body 2 comprises a cylindrical barrel 5c with a bottom, a round cover-shaped supporting frame 5a is arranged at the bottom of the barrel 5c with a bottom, a round hole is arranged in the middle of the supporting frame 5a, the bottom is a plane, a stop rod 5b is welded on the bottom plane of the supporting frame 5a, the outer cylindrical surface of the supporting frame 5a is matched with the inner cylindrical surface of the barrel 5c with a bottom, and three small bulges are arranged on the circumference of the outer cylindrical surface of the supporting frame 5a to realize fixation. The case 5 and the valve body flange plate 2e are positioned at the upper end of the valve body 2, and the lower end opening end of the bottomed cylindrical body 5c is butt-welded to a step portion fixed to the valve body upper flange plate 2e by welding or the like.

A rotor magnetic ring 4l with a permanent magnet in the rotor 4 is directly injected in the middle section of the screw shaft, a small long groove is arranged at the upper end of a central shaft 4d of the screw shaft, an annular groove is arranged on the outer circumferential surface of the shaft 4d close to the bottom of the small long groove, a spring guide rail 4a and a sliding ring 4b are arranged on the outer circumference of the shaft 4d, a limiting end of the spring guide rail 4a is transversely embedded into the small long groove, and after being clamped and fastened by an elastic clamping ring 4c, the upper end of the shaft 4d is movably matched with a middle round hole of a supporting frame 5 a.

The slide ring 4b can slide up and down in a spiral groove formed by the spring guide 4a and the upper periphery of the shaft 4d, and limit positions are carried out at two ends, and the uppermost limit and the lower limit of the up-and-down movement of the rotor 4 are realized by a brake mechanism formed by the spring guide 4a, the slide ring 4b and a stop rod 5b which are fixed on the shaft 4 d.

The rotor 4 is mounted inside the case 5, the stator 6 is mounted outside the case 5, the stator 6 has a middle engaging hole engaged with the case 5, the stator 6 accommodates a stator coil 6c and yokes 6d and 6a wound around a coil bobbin 6b vertically inside the stator 6, the stator coil 6c is molded with an unsaturated resin 6e, and the stator coil 6c is connected to a power source through a lead wire 7 and a terminal 7a provided on the outer periphery of the stator. After the stator coil 6c is energized, the

yokes

6d and 6a are excited to rotate the rotor 4, and the valve needle 4f in the rotor 4 slides to open and close the front end valve port 4h by the screw feed mechanism, thereby adjusting the refrigerant flow rate.

When the elastic snap ring 4c is installed, the requirement on the position size precision of the bottom end of the small long groove and the annular groove is high, and when the position size is small, the elastic snap ring 4c cannot be clamped into the annular groove; when the position size is large, the spring guide rail 4a has a gap in the small long groove, when the electronic expansion valve works, the spring guide rail 4a and the sliding ring 4b generate axial movement along the small long groove, the limiting precision of the rotor 4 is influenced, and therefore the performance of the valve is influenced.

Based on this, the inventors of the present application have conducted long-term creative efforts to arrive at the following inventions.

A rotor assembly 100 according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.

As shown in fig. 3 to 9, a rotor assembly 100 according to an embodiment of the present invention includes a rotor magnet ring 10, a screw shaft 20, a spring guide 30, and a fixing member 40.

Specifically, the rotor magnetic ring 10 is formed into a hollow column shape with one open end, the other end of the rotor magnetic ring 10 is provided with a channel 11 penetrating along the axial direction of the rotor magnetic ring 10, the screw shaft 20 is inserted into the channel 11 along the axial direction of the channel 11, one end of the screw shaft 20 extends out of the open end of the rotor magnetic ring 10 and is provided with a long groove 21 extending along the axial direction of the screw shaft, the other end of the screw shaft 20 extends out of the channel 11, one end of the spring guide rail 30 is embedded in the long groove 21, the other end of the spring guide rail 30 is spirally wound on the outer wall surface of the screw shaft 20 along the axial direction of the screw shaft 20 towards the other end, and the fixing piece 40 is welded and connected with at least one.

In other words, the rotor assembly 100 according to the embodiment of the present invention mainly includes a rotor magnetic ring 10, a screw shaft 20, a spring guide 30, and a fixing member 40, the rotor magnetic ring 10 is formed in a hollow cylindrical shape, one end of the rotor magnetic ring 10 is open, the other end of the rotor magnetic ring 10 is provided with a channel 11, the channel 11 penetrates in an axial direction of the rotor magnetic ring 10, the screw shaft 20 is inserted into the channel 11, the screw shaft 20 extends in the axial direction of the channel 11, one end of the screw shaft 20 is provided with a long groove 21, one end of the screw shaft 20 extends out of the open end, the spring guide 30 is provided on an outer wall surface of the screw shaft 20, one end of the spring guide 30 is embedded in the long groove 21, the other end of the spring guide 30 is spirally wound in the axial direction of the screw shaft 20, the fixing member 40 is provided at one end of the spring guide 30 and an, so that one end of the spring guide 30 can be pressed in the elongated slot 21 by the fixing member 40.

Therefore, according to the rotor assembly 100 of the embodiment of the present invention, the rotor magnetic ring 10, the screw shaft 20, the spring guide 30 and the fixing member 40 are combined, after one end of the spring guide 30 is embedded in the elongated slot 21, one end of the spring guide 30 is pressed by the fixing member 40, and the fixing member 40 is fixed by welding, so that there is no need to process a high-position-precision annular groove on the outer circumferential surface of the screw shaft 20, and the axial clearance play of the spring guide 30 after being fixed in the elongated slot 21 is also prevented.

According to an embodiment of the present invention, the fixing member 40 and the screw shaft 20 may be fixedly connected by laser welding, and the laser welding is a non-contact welding for the workpiece, so as to avoid the change and influence of a large current during welding such as argon arc welding, plasma welding, resistance welding, etc. on the magnetic performance of the rotor magnetic ring 10, and ensure the magnetic ring performance.

As shown in fig. 4 to 9, the fixing member 40 is alternatively formed as a snap ring.

In some embodiments of the invention, the fixture 40 may be connected to the outer circumference of the screw shaft 20 by circumferential welding.

According to one embodiment of the invention, the fixture 40 is attached to the outer circumference of the screw shaft 20 by a plurality of spot welds that are circumferentially spaced, with the spot welds or the circumferential welds being selected based on the laser weld strength.

As shown in fig. 5 and 8, alternatively, the cross section of the snap ring is formed in a rectangular shape.

Further, the elastic snap ring may be formed of a stainless steel wire, and may be wound by the stainless steel wire having elasticity.

In summary, the rotor assembly 100 according to the embodiment of the present invention, which adopts the combination of the rotor magnetic ring 10, the screw shaft 20, the spring guide 30 and the fixing member 40, has the advantages of simple and reliable structure, easy manufacture, stable performance of the finished product, and reduced production cost.

As shown in fig. 10, a method 200 of assembling a rotor assembly according to an embodiment of the present invention includes:

and S1, sleeving the spring guide rail 30 on the screw shaft 20 and transversely embedding one end of the spring guide rail 30 into the long groove 21 of the screw shaft 20.

S2, the fixing member 40 is fitted over the screw shaft 20 and the fixing member 40 is pressed against one end of the spring guide 30.

S3, the boundary between the anchor 40 and the outer peripheral surface of the screw shaft 20 is laser welded.

Alternatively, in step S3, the boundary between the elastic snap ring and the outer peripheral surface of the screw shaft 20 is circumferentially welded along the outer periphery of the screw shaft 20 by one turn.

Further, in step S3, the boundary between the elastic snap ring and the outer peripheral surface of the screw shaft 20 is welded at intervals along the outer periphery of the screw shaft 20, and spot welding or circumferential welding may be selected according to the laser welding strength.

In summary, according to the assembling method 200 of the rotor assembly of the embodiment of the present invention, the fixing member 40 and the screw shaft 20 are fixed by laser welding, and since the laser welding is non-contact welding to the workpiece, the change and influence of a large current during welding such as argon arc welding, plasma welding, resistance welding, etc. on the magnetic performance of the rotor magnetic ring 10 are avoided, and the magnetic ring performance can be ensured.

The electronic expansion valve according to an embodiment of the present invention includes the rotor assembly 100 of the above embodiment, and the electronic expansion valve may further include a valve body, a housing and a stator assembly, the flow rate of the refrigerant may be adjusted by the valve needle 50 contacting and separating from a valve seat in the valve chamber, the housing is fixed on the valve body, the rotor assembly 100 contacting and separating from the valve needle 50 is disposed in the housing, the stator assembly is externally installed on the housing and drives the rotor assembly 100 to rotate, and a stepping motor may be configured by the rotor assembly 100 and the stator assembly. The screw shaft 20 in the rotor assembly 100 may be an integral molding, or may be formed by installing the screw 22 and the shaft 23 separately, the rotor magnetic ring 10 with permanent magnet may be directly injection-molded on the screw 22, the limiting mechanism formed by the spring guide 30 and the sliding ring 60 may be disposed on the outer circumference of the shaft 23, the valve needle 50 may be disposed at the lower end of the screw 22, the driving mechanism for making the valve needle 50 contact with and separate from the valve seat may include a guide nut, the guide nut is fixed by extending from the valve body to the rotor assembly 100, an internal thread portion is disposed in the guide nut, the outer circumference of the lower end of the screw 22 has an external thread portion 26 screwed with the internal thread portion, and the upper end of the screw 22 is coupled with the shaft 23 in an interference fit. The driving mechanism can be a thread feeding mechanism, the valve needle 50 can slide, an axial small hole can be arranged at the central position of the upper end part of the valve needle 50, a transverse small hole 51 is arranged at the middle section of the valve needle 50, the axial small hole and the transverse small hole 51 are communicated with each other and form an equal pressure balance hole in a valve chamber and a shell, the valve needle 50 is pressed downwards by a compression spring 70 which is arranged in an inner cavity 25 at the lower end part of the screw rod 22 in a compression mode, in order to increase the flexibility of the compression spring 70 rotating along the spring center, a smooth gasket 80 is arranged between the end surface of the compression spring 70 and the bottom of the inner cavity 25 at the lower end part of the screw rod 22, in order to limit the valve needle 50 to be pushed out of the inner cavity 25 by the compression spring 70, a limit retaining ring 90 is arranged at.

Since the rotor assembly 100 according to the embodiment of the present invention has the above technical effects, the electronic expansion valve according to the embodiment of the present invention also has corresponding technical effects, i.e., has the advantages of simple and reliable structure, easy manufacture, stable performance of the finished product, reduced cost, etc.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A rotor assembly, comprising:

the rotor magnetic ring is formed into a hollow column shape with one open end, and the other end of the rotor magnetic ring is provided with a channel which is through along the axial direction of the rotor magnetic ring;

the screw rod shaft is inserted into the channel along the axial direction of the channel, an annular groove is not formed in the outer peripheral surface of the screw rod shaft, one end of the screw rod shaft extends out of the open end of the rotor magnetic ring and is provided with a long groove extending along the axial direction of the rotor magnetic ring, and the other end of the screw rod shaft extends out of the channel;

one end of the spring guide rail is embedded in the long groove, and the other end of the spring guide rail spirally surrounds the outer wall surface of the screw shaft towards the other end along the axial direction of the screw shaft;

a fixing member welded to at least a portion of the screw shaft to press one end of the spring guide in the elongated slot,

the fixing piece is fixedly connected with the screw rod shaft through laser welding,

the fixing member is formed as an elastic snap ring,

the fixing piece is connected with the periphery of the screw rod shaft through circumferential welding.

2. The rotor assembly of claim 1 wherein the fixture is connected to the outer periphery of the screw shaft by a plurality of circumferentially spaced spot welds.

3. The rotor assembly of claim 1 wherein the snap ring is formed rectangular in cross-section.

4. The rotor assembly of claim 1 wherein the snap ring is formed as a stainless steel wire.

5. A method of assembling a rotor assembly as claimed in any one of claims 1 to 4, comprising:

s1, sleeving a spring guide rail on the screw rod shaft and transversely embedding one end of the spring guide rail into an elongated slot of the screw rod shaft;

s2, sleeving a fixing piece on the screw rod shaft and enabling the fixing piece to press one end of the spring guide rail;

and S3, welding the junction of the fixing piece and the outer peripheral surface of the screw rod shaft by laser.

6. An assembling method of the rotor assembly according to claim 5, wherein in step S3, the boundary between the snap ring and the outer peripheral surface of the screw shaft is circumferentially welded along the outer periphery of the screw shaft by one turn.

7. The method of assembling a rotor assembly according to claim 6, wherein in step S3, the interface between the snap ring and the outer peripheral surface of the screw shaft is welded at intervals along the outer periphery of the screw shaft.

8. An electronic expansion valve comprising a rotor assembly as claimed in any one of claims 1 to 4.