CN111140687A

CN111140687A - Electronic expansion valve

Info

Publication number: CN111140687A
Application number: CN201910097699.0A
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: 2018-11-06
Filing date: 2019-01-31
Publication date: 2020-05-12

Abstract

The electronic expansion valve comprises a valve seat, a first connecting pipe part and a second connecting pipe part, wherein the valve seat comprises a peripheral wall part and a valve opening part, the electronic expansion valve comprises a first valve cavity and a second valve cavity, the first valve cavity is positioned above the valve opening part, the second valve cavity is positioned below the valve opening part, the valve opening is communicated with the first valve cavity and the second valve cavity, the first connecting pipe part is fixedly connected with the valve seat and directly communicated with the first valve cavity, the second connecting pipe part is fixedly connected with the valve seat and limits the second valve cavity with the valve seat, and the inner diameter of the valve opening is smaller than the inner diameter of the second valve cavity. The electronic expansion valve provided by the invention comprises a first valve cavity and a second valve cavity, wherein a refrigerant enters the second valve cavity from the first valve cavity after passing through a valve port, and the flow rate and the pressure of the refrigerant can be reduced after the refrigerant passes through the valve port because the inner diameter of the valve port is smaller than that of the second valve cavity, so that the noise of the refrigerant passing through the electronic expansion valve is improved, and the requirement of some systems for improving the noise is met.

Description

Electronic expansion valve

[ technical field ] A method for producing a semiconductor device

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

[ background of the invention ]

The refrigeration system generally includes a compressor, a throttling element, an outdoor heat exchanger, and other components, and the throttling element may be an electronic expansion valve for adjusting the flow rate of the refrigerant. When the refrigerant enters the electronic expansion valve, a certain noise may be generated. The noise of refrigerant passing through the electronic expansion valve is a technical subject which has been studied by related technicians of the electronic expansion valve and the refrigeration system for a long time. Therefore, the structure of the electronic expansion valve can be optimized to reduce the noise when the refrigerant flows through the electronic expansion valve.

[ summary of the invention ]

The invention aims to provide an electronic expansion valve which is used for improving the noise problem of a refrigerant flowing through the electronic expansion valve.

In order to realize the purpose, the following technical scheme is adopted:

the electronic expansion valve comprises a valve seat, a first connecting pipe part and a second connecting pipe part, wherein the valve seat comprises a peripheral wall part and a valve port part, the electronic expansion valve comprises a first valve cavity and a second valve cavity, the first valve cavity is positioned on one side above the valve port part, the second valve cavity is positioned on one side below the valve port part, the valve port part is provided with a valve port, the valve port can be communicated with the first valve cavity and the second valve cavity, the first connecting pipe part is fixedly connected with the valve seat and directly communicated with the first valve cavity, the second connecting pipe part is fixedly connected with the valve seat and limits the second valve cavity with the valve seat, and the inner diameter or the through diameter of the valve port is smaller than that of the second valve cavity.

The electronic expansion valve provided by the invention is characterized in that a first valve cavity and a second valve cavity are respectively arranged on two sides of a valve port part, when a refrigerant enters the second valve cavity from the first valve cavity after passing through the valve port of the valve port part, the flow rate and the pressure of the refrigerant can be reduced after passing through the valve port in the direction because the inner diameter of the valve port is smaller than that of the second valve cavity, and the second valve cavity is relatively large, so that the noise when passing through the electronic expansion valve is improved, and the problem of noise which is always solved by technical personnel in the field for a long time is solved.

[ description of the drawings ]

FIG. 1 is a schematic structural diagram of an electronic expansion valve according to a first embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of the valve seat of FIG. 1;

FIG. 3 is a schematic sectional view of the second socket of FIG. 1;

FIG. 4 is a schematic cross-sectional view of the valve seat of FIG. 1 after engagement with the first and second nozzle portions;

fig. 5 is a schematic cross-sectional view of a second embodiment of the present invention.

[ detailed description ] embodiments

In order to make the technical solutions of the present invention better understood, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1 to 4, fig. 1 is a schematic structural view of an electronic expansion valve according to a first embodiment of the present invention, fig. 2 is a schematic sectional view of a valve seat thereof, fig. 3 is a schematic sectional view of a second connection pipe of fig. 1, and fig. 4 is a schematic sectional view of the valve seat of fig. 1 after being engaged with a first connection pipe portion and a second connection pipe portion.

It should be noted that, the present invention is described with respect to a specific electronic expansion valve structure, and is intended to improve a valve seat of the electronic expansion valve and a component structure connected with the valve seat, other components of the electronic expansion valve, such as a magnetic rotor assembly, a screw valve needle assembly, a nut assembly, a stopping device, etc., are not limited herein, and the technical solution of the present invention is not particularly limited to the above components, and those skilled in the art can apply the present invention to all similar electronic expansion valve structures according to the technical solution disclosed in the present invention. The embodiments of the present invention are described with respect to the magnetic rotor assembly, the screw valve needle assembly and other components, which are only for convenience of understanding the basic operation principle of the electronic expansion valve and are not limited thereto.

The electronic expansion valve 1 has a valve seat 11, the valve seat 11 is fixedly connected with a first pipe connecting part 12 and a second pipe connecting part 13, as shown in the direction of fig. 1, a valve body part 15 of the valve body part is arranged on one side above the valve seat 11, the valve body part is approximately in a cup shape with an opening at the bottom, the bottom of the valve body part is provided with an opening and is fixedly connected with the valve seat 11, specifically, a step can be arranged at the upper end of the valve seat 11, the bottom opening of the valve body part 15 is matched with the step and is welded and fixed with the step, or the valve body part 15 and the step are fixed relatively by adopting other forms, such as clamping and then welding and fixing, etc., the invention does not limit the specific matching structure.

The upper side of the valve body part 15 is further provided with a shell 16, the shell 16 and the valve body part 15 can be fixed in a welding mode, so that the shell 16, the valve body part 15 and the valve seat 11 are fixedly connected, and a magnetic rotor assembly 17, a screw rod valve needle assembly 18 and a nut assembly 19 are arranged in the space among the three. It should be noted that, in the above structure, the valve body 15 is not necessarily present, and when the valve body 15 is not present, the housing 16 may be directly and fixedly connected to the valve seat 11, or may be fixed by another component, for example, by directly extending the outer edge portion of the valve seat 11 upward and then welding and fixing the outer edge portion to the housing 16.

In the space inside the housing 16, the valve body 15 and the valve seat 11, there are provided a magnetic rotor assembly 17, a screw needle assembly 18 and a nut assembly 19, the magnetic rotor assembly 17 can induce the electromagnetic force of the electromagnetic coil to rotate, the magnetic rotor assembly 17 includes a magnetic rotor 171 and a connecting plate 172 fixedly connected or integrally arranged with the magnetic rotor 171, the screw needle assembly 18 includes a screw 181, the screw 181 is fixedly connected with the connecting plate 172, in this way, the screw 181 is connected with the magnetic rotor assembly 17 through the connecting plate 172 to form a whole, specifically, the screw 181 and the connecting plate 172 can be fixedly connected in a welding manner or connected in other fixed connection or limit connection manners such as clamping, crimping, etc.

The screw needle assembly further comprises a needle 182, a sleeve part 183, a sleeve cover 184, a fixing part 185, a spring 186 and a support part 187, the screw 181 and the needle 182 are in floating connection through the sleeve, the sleeve comprises the sleeve part 183 and the sleeve cover 184, the sleeve part 183 is in a cup shape with an opening at the bottom, the bottom of the sleeve part is provided with an opening, the needle 182 penetrates through the opening to be at least partially positioned in the first valve cavity a, and the valve core 182 can move relative to the valve port under the action of the drive so as to cooperate with the valve port 1121 for adjusting the throttling during the operation of the electronic expansion valve. That is, during the operation of the electronic expansion valve, the valve needle 182 can move up and down relative to the sleeve portion 183 within a certain stroke to adjust the valve port opening, and when the valve element abuts against the valve port, the valve element 182 can move relative to the sleeve portion 183 against the spring force within a certain range without coming off the sleeve. A sleeve cover 184 is arranged on the top of the sleeve part 183, the sleeve part 183 and the sleeve cover 184 are relatively fixed or limited, the sleeve cover 184 is provided with a contact part, the lower end part of the screw rod 181 is fixedly connected with a fixing part 185, the fixing part 185 is provided with a wing part, the wing part faces one side of the valve core, a spring 186 is further arranged and supported by a support part 187, one end of the spring 186 is contacted with the wing part facing one side of the valve core, and the other side is contacted with the support part 187; in the assembling process, the screw 181 may be inserted through the sleeve cover 184, the fixing member 185 may be fixedly connected to the screw 181, and then the screw may be assembled with the sleeve 183, and the sleeve cover 184 may be assembled with the sleeve 183. In this way, the abutting portion of the sleeve cover 184 is disposed opposite to the wing portion of the fixing member 185, forming a limit structure, and at the same time, the sleeve and the screw shaft 181 are formed into a floating connection structure like a suspension. The sleeve portion 183 and the screw 181 cannot be disengaged from each other but can move relatively. The disengagement described herein means that the sleeve portion 183 and the lead screw 181 are separated into two separate parts without any limitation to each other, not only that they are not in physical contact.

The nut assembly 19 comprises a nut 191 and a connecting piece 192, the nut 191 is fixedly connected with the connecting piece 192, the connecting piece 192 can be formed by punching a metal plate, the nut 191 is fixedly arranged with the shell 16 and/or the valve body part 15 through the connecting piece 192 made of metal, the nut 191 can be made of non-metal materials and is formed by injection molding by taking the connecting piece 192 as an insert, and the connecting piece 192 is fixedly connected with the valve body part 15 in a welding mode. When the valve body portion is not provided, the connecting piece 192 may be fixedly connected to the valve seat 11 or the housing by welding.

The nut 191 has a through hole running through along the axial direction, and an internal thread is arranged inside the through hole, and correspondingly, an external thread is arranged on the outer peripheral surface of the screw rod 181, so that when the magnetic rotor component 17 rotates, the screw rod 181 linked with the magnetic rotor component rotates and moves up and down relative to the nut component 19 under the action of a thread pair, and the valve needle 182 is driven to move up and down within a certain range.

In one embodiment, the valve seat 11 includes a peripheral wall portion 111 and a valve mouth portion 112. The valve port 112 and the peripheral wall 111 may be formed by cutting, the valve port 112 and the peripheral wall 111 may also be formed by welding, the valve port 112 is provided with a valve port 1121, the electronic expansion valve has a first valve cavity a on the upper side of the valve port 112, and has a second valve cavity B on the lower side of the valve port 112, when the valve needle 182 moves up and down, the valve needle 182 is far away from or close to the valve port 112, so that the flow area between the valve port 1121 and the valve needle 182 changes, thereby throttling the refrigerant and controlling the flow rate of the refrigerant passing through the valve port 1121.

The valve seat 11 is provided with a first connecting port part 11111 which is matched and fixedly connected with the first connecting pipe part 12 on the peripheral wall part 111, and the first connecting pipe part 12 and the first connecting port part 11111 can be fixedly connected by welding.

The second connecting pipe part 13 comprises a small-diameter part 131, a large-diameter part 132 and a transition part 133, the small-diameter part 131 comprises an interface part 1312 and a bent pipe part 1311, and the interface part 1312 is used for connecting with other connecting pipes or interfaces in the system; specifically, during the process, the material may be blanked, and then one end of the pipe may be flared to form the large diameter portion 132, and the transition portion 133 may be formed between the large diameter portion 132 and the small diameter portion 131. The second pipe connecting portion 13 is fixedly connected to the valve seat by welding or the like through the large diameter portion 132. Specifically, a step 1123 may be provided at the bottom of the valve seat, the large diameter portion 132 may be fitted around the step 1123 to be matched, and then the two may be welded and fixed. Of course, as an equivalent embodiment, an annular groove may be provided at the bottom of the valve seat 11, the large diameter portion 132 is matched with the annular groove, and then the two are welded and fixed, the valve seat defines the first valve chamber a, that is, the valve port 112 and the peripheral wall 111 define the first valve chamber a, the second connecting pipe portion and the valve port 112 define the second valve chamber B or the second connecting pipe portion and the valve port 112 and a part of the peripheral wall define the second valve chamber B, that is, the second connecting pipe portion and the valve seat define the second valve chamber B, the second valve chamber is located in the large diameter portion 132, and the second valve chamber B is formed by the transition portion 133, the large diameter portion 132 and the valve seat in this embodiment.

In the embodiment, the inner diameter of the second valve cavity B is d1, the inner diameter of the small diameter part 131 of the second connecting pipe part 13 is d2, and the inner diameter of the valve port 1121 is d3, so that in order to ensure the effect of improving noise of the valve, d1 and d2 satisfy d1 > d2, d1 and d3 generally satisfy d1 is greater than or equal to 3d3, and d1 is less than or equal to 20d 3. In order to make the noise improving effect of the electronic expansion valve more obvious, d1 and d2 can be further set to d1 being more than or equal to 1.3d2, so that when the refrigerant flows from the first connecting pipe part to the second connecting pipe part, the flow speed and pressure of the refrigerant can be obviously reduced when the refrigerant flows out of the valve port, and the noise improving effect is more obvious. The shape of the valve port 1121 may have various configurations, i.e., there may be a plurality of different inner diameters or variations for the entire valve port 1121, and in this embodiment, the inner diameter d3 of the valve port refers to the inner diameter of the smallest part of the valve port 1121. When the second valve cavity B is a regular cylindrical cavity body, d1 is the inner diameter of the second valve cavity, and when the second valve cavity B is irregular, such as two flaring openings like a stepped cylinder, a truncated cone or a combination of a plurality of structures, d2 is defined as the equivalent inner diameter of the second valve cavity B. The inner diameter of the small diameter portion 131 may also be referred to as the through-flow inner diameter of the second joint pipe portion 13. In addition, due to the requirements of different applications, the electronic expansion valve needs to use the valve ports 1121 with different inner diameters, that is, under the condition that the overall size of the valve body is kept unchanged, there are electronic expansion valves of various models and specifications, in the electronic expansion valves of different models and specifications, the sizes of the valve ports 1121 are usually different, when the inner diameter of the valve port 1121 is larger, the ratio of d1 to d3 is closer to 3, and when the inner diameter of the valve port 1121 is smaller, the ratio of d1 to d3 is closer to 20.

In addition, the cross section of the valve port is not necessarily circular, and the cross section of the second valve chamber is not necessarily circular, and in this case, the diameter of the second valve chamber B is larger than the diameter d3 of the valve port 1121, and the diameter d1 of the second valve chamber B is larger than the diameter d2 of the small diameter portion of the second connecting pipe portion, as measured by the diameter. Further, in order to make the noise-improving effect more remarkable, the passage diameter d1 of the second valve chamber B, the passage diameter d2 of the second pipe connection part, and the passage diameter d3 of the valve port 1121 satisfy the following conditions: d1 is more than or equal to 1.3d2, d1 is more than or equal to 3d3, and d1 is less than or equal to 20d 3. Here, the diameter corresponds to the equivalent inner diameter, i.e., the value of the inner diameter when the cross-sectional area at that point is changed to a circular shape of the same cross-sectional area, or both have the same cross-sectional area, and thus have the same flow area.

In the electronic expansion valve provided in this embodiment, the first connecting pipe portion 12 is fixedly connected to the valve seat at the first connecting portion 11111, so that the internal space of the first connecting pipe portion 12 is directly communicated with the first valve chamber a, the valve port portion 112 separates the first valve chamber a from the second valve chamber B, and the first valve chamber a and the second valve chamber B are communicated with each other by the valve port 1121 of the valve port portion 112, therefore, the first connecting pipe portion 12 and the second connecting pipe portion 13 can also be communicated through the valve port, it should be noted that the direct communication described in this embodiment is relative to the valve port 1121 of the valve port portion 112, specifically, the first connecting pipe portion 12 needs to be communicated with the second valve chamber B through the valve port 1121, at this time, the first connecting pipe portion 12 is not directly communicated with the second valve chamber B, the first connecting pipe portion 12 does not need to be communicated with the first valve chamber a through the valve port 1121, at this time, the first connecting pipe portion 12 is directly communicated with the, further, the "communication" described in the present embodiment does not consider other components than the valve seat 11 and the first joint pipe portion 12.

In the electronic expansion valve provided in this embodiment, two valve cavities are provided, and in a flow direction, the refrigerant enters the second valve cavity B from the first valve cavity a after passing through the valve port 1121 of the valve port portion 112, because the size of the cross section of the valve port 1121 is different from that of the cross section of the second valve cavity B, the second valve cavity B is relatively large, and the flow rate and pressure of the refrigerant after passing through the valve port in this direction are reduced, so that noise generated when the refrigerant passes through the electronic expansion valve is improved. In addition, the second connecting pipe does not necessarily have to be of one-piece construction. It may also consist of two and over-connection pipes, without limitation.

Referring to fig. 5, fig. 5 is a schematic cross-sectional view of a second embodiment of the present invention. This embodiment differs from the above embodiments in that the second pipe connecting portion has a different structure, the second pipe connecting portion 13a includes a small diameter portion 131a, a large diameter portion 132a, and a transition portion 133, the transition portion 133 is located between the small diameter portion 131a and the large diameter portion 132a, or the transition portion 133 connects the small diameter portion 131a and the large diameter portion 132 a; the large-diameter part 132a comprises a straight pipe part 1321 and an elbow part 1322, the straight pipe part 1321 can be used for being matched and connected with a valve seat, and the small-diameter part 131a is used for being connected with other connecting pipes or interfaces in the system; specifically, during the machining, the material is first cut, and then the pipe is reduced at one end to form the small diameter portion 131a, and the transition portion 133 is formed between the large diameter portion 132a and the small diameter portion 131 a. The valve seat 11a and the second pipe connecting part 13a are welded and fixed to form a second valve chamber B, the shape of the second valve chamber B is relatively complex, the shape of the second valve chamber B is not completely regular, the second valve chamber B is relatively long in the length direction, and the second valve chamber B comprises an inner space of the bent pipe part 1322, so that the noise reduction effect is good, but the appearance of the electronic expansion valve is relatively large.

The electronic expansion valve comprises a valve seat, a first connecting pipe part and a second connecting pipe part, wherein the valve seat comprises a peripheral wall part 111 and a valve port part 112, the valve seat, the first connecting pipe part and the second connecting pipe part are welded and fixed to form a first valve cavity A and a second valve cavity B, the first valve cavity A is relatively positioned on one side above the valve port part 112, the second valve cavity B is relatively positioned on one side below the valve port part 112, the valve port part 112 is provided with a valve port 1121, the valve port 1121 can be communicated with the first valve cavity A and the second valve cavity B, the first connecting pipe part is directly communicated with the first valve cavity A, and the second connecting pipe part and the valve seat limit the second valve cavity B, so that the through diameter or the inner diameter of the valve port 1121 is smaller than the inner diameter or the through.

Further, the second connecting pipe part comprises a large diameter part and a small diameter part, the large diameter part is matched and fixed with the valve seat, the large diameter part is larger than the small diameter part, and the second valve cavity B is positioned in the large diameter part; the inner diameter d1 of the second valve chamber B, the inner diameter d2 of the second pipe connecting part and the inner diameter d3 of the valve port 1121 satisfy the following conditions: d1 is more than or equal to 1.3d2, d1 is more than or equal to 3d3, and d1 is less than or equal to 20d 3; or the diameter d1 of the second valve chamber B, the diameter d2 of the second connecting pipe part and the diameter d3 of the valve port 1121 satisfy the following conditions: d1 is more than or equal to 1.3d2, d1 is more than or equal to 3d3, and d1 is less than or equal to 20d 3.

Alternatively, the inner diameter of the second joint pipe portion near the valve port portion is 1.3 times or more the inner diameter of the small diameter portion of the second joint pipe.

The second connection pipe part may further include a variable diameter part 133, the variable diameter part 133 may be located between a small diameter part and a large diameter part, the large diameter part may be larger than the small diameter part, the large diameter part may be formed by flaring a copper pipe, the small diameter part may include a bent pipe part 1311 and a connecting part 1312, and the second connection pipe part may be fixedly connected to the valve seat through the large diameter part by welding.

Or, the second connection pipe portion may include a variable diameter portion 133, the variable diameter portion 133 is located between the small diameter portion and the large diameter portion, the small diameter portion 132a may be formed by necking a copper pipe, the large diameter portion 132a may include a bent pipe portion 1322 and a straight pipe portion 1321, and the second connection pipe portion is fixedly connected to the valve seat by welding through the large diameter portion. The second joint pipe portion may have a diameter near the valve port portion that is 1.3 times or more larger than a diameter of the small diameter portion of the second joint pipe.

The structure of the valve seat matched with the second connecting pipe part can be various, for example, a step part 1123 is arranged at the bottom, and a large-diameter part of the second connecting pipe part is sleeved and matched with the step part 1123 and is welded and fixed; or, an annular groove is arranged at the bottom of the valve seat, and the large-diameter part is matched with the annular groove and is welded and fixed; the small diameter portion, the large diameter portion, and the variable diameter portion 133 may be an integral structure, and the second connection pipe portion may not be an integral structure, that is, may be formed by assembling.

It should be noted that, in the present embodiment, the terms of orientation such as up, down, left, right, etc. are used as references in the drawings of the specification and are introduced for convenience of description; and ordinal numbers such as "first", "second", etc. in the names of the components are also introduced for convenience of description, and do not imply any limitation on any order of the components, and since the functions of some parts between the components provided in the above-described embodiments are the same, the present specification adopts a uniform naming manner for these parts.

The electronic expansion valve provided in the related art is described in detail above, and a specific example is applied in this text for illustration, and the above description of the embodiment is only used to help understanding the method of the present invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. The electronic expansion valve is characterized by comprising a valve seat (11), a first pipe connecting part (12) and a second pipe connecting part (13, 13a), wherein the valve seat (11) comprises a peripheral wall part (111) and a valve port part (112), the electronic expansion valve comprises a first valve cavity (A) and a second valve cavity (B), the first valve cavity (A) is positioned on one side above the valve port part (112), the second valve cavity (B) is positioned on one side below the valve port part (112), the valve port part (112) is provided with a valve port (1121), the valve port (1121) can be communicated with the first valve cavity (A) and the second valve cavity (B), the first pipe connecting part (12) is fixedly connected with the valve seat (11) and is directly communicated with the first valve cavity (A), the second pipe connecting part (13, 13a) is fixedly connected with the valve seat (11), and the second pipe connecting part (13, 13a) the valve seat defines the second valve chamber (B), and the inner diameter of the valve port (1121) is smaller than that of the second valve chamber (B).

2. An electronic expansion valve according to claim 1, wherein the second nozzle part comprises a large diameter part, a small diameter part, the large diameter part being larger than the small diameter part, the second valve chamber (B) being located within the large diameter part; the inner diameter d1 of the second valve cavity (B), the inner diameter d2 of the second connecting pipe part (13, 13a) and the inner diameter d3 of the valve port (1121) satisfy the following conditions: d1 is more than or equal to 1.3d2, d1 is more than or equal to 3d3, and d1 is less than or equal to 20d 3.

3. The electronic expansion valve according to claim 1 or 2, wherein an inner diameter of the second joint pipe portion near the valve port portion is 1.3 times or more an inner diameter of the small diameter portion of the second joint pipe.

4. The electronic expansion valve is characterized by comprising a valve seat (11), a first pipe connecting part (12) and second pipe connecting parts (13, 13a), wherein the valve seat (11) comprises a peripheral wall part (111) and a valve opening part (112), the electronic expansion valve comprises a first valve cavity (A) and a second valve cavity (B), the first valve cavity (A) is positioned on one side above the valve opening part (112), the second valve cavity (B) is positioned on one side below the valve opening part (112), the valve opening part (112) is provided with a valve opening (1121), the valve opening (1121) can be communicated with the first valve cavity (A) and the second valve cavity (B), the first pipe connecting part (12) is fixedly connected with the peripheral wall part of the valve seat (11) through welding, the first pipe connecting part (12) is directly communicated with the first valve cavity (A), and the second pipe connecting parts (13, 13a) are fixedly connected with the valve seat (11) through welding, the second connecting pipe part (13, 13a) comprises a large-diameter part and a small-diameter part, the through diameter of the second valve cavity (B) is larger than the through diameter d3 of the valve port (1121), the through diameter d1 of the second valve cavity (B) is larger than the through diameter d2 of the small-diameter part of the second connecting pipe part, and the through diameter of the large-diameter part is larger than the through diameter of the small-diameter part.

5. An electronic expansion valve according to claim 4, wherein the second valve chamber (B) is located in the large diameter portion, and the through diameter d1 of the second valve chamber (B), the through diameter d2 of the second piping portion (13, 13a), and the through diameter d3 of the valve port (1121) satisfy the following conditions: d1 is more than or equal to 1.3d2, d1 is more than or equal to 3d3, and d1 is less than or equal to 20d 3.

6. The electronic expansion valve according to claim 5, wherein a diameter of the second joint pipe portion near the valve port portion is 1.3 times or more larger than a diameter of the small diameter portion of the second joint pipe.

7. An electronic expansion valve according to any one of claims 2, 3, 4, 5 and 6, wherein the second connecting pipe portion (13) comprises a diameter-variable portion (133), the large diameter portion (132) is larger than the small diameter portion (131), the large diameter portion (132) is formed by flaring, the diameter-variable portion (133) is located between the small diameter portion (131) and the large diameter portion (132), the small diameter portion (131) comprises a bent pipe portion (1311) and a connecting portion (1312), and the second connecting pipe portion (13) is fixedly connected with the valve seat through the large diameter portion by welding.

8. An electronic expansion valve according to any of claims 2-6, wherein the second connecting pipe section (13a) comprises a reduced diameter section (133), the reduced diameter section (133) being located between the small diameter section (131) and the large diameter section (132a), the small diameter section (132a) being machined with a reduction, the large diameter section (132a) comprising a bent pipe section (1322) and a straight pipe section (1321), the second connecting pipe section being fixedly connected to the valve seat by welding via the large diameter section.

9. The electronic expansion valve according to claim 7 or 8, wherein a step portion (1123) is provided at the bottom of the valve seat (11), and the large diameter portion (132) is fitted over and welded to the step portion (1123); or an annular groove is formed in the bottom of the valve seat (11), and the large-diameter part (132) is matched with the annular groove and is welded and fixed; the small diameter part, the large diameter part and the variable diameter part (133) are of an integral structure.