CN112066608A

CN112066608A - Expansion valve and refrigeration control system

Info

Publication number: CN112066608A
Application number: CN202011009536.1A
Authority: CN
Inventors: 周亮
Original assignee: Beijing Jingyi Automation Equipment Co Ltd
Current assignee: Beijing Jingyi Automation Equipment Co Ltd
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2020-12-11

Abstract

The invention relates to the field of valves, and provides an expansion valve and a refrigeration control system. The expansion valve comprises a pressure sensor, an elastic part, a driving part, a valve body, a valve rod and a fixed block, wherein the valve rod and the fixed block are arranged in the valve body; a liquid outlet is formed at the bottom end of the valve body, and a liquid inlet is formed on the side wall of the valve body; the driving piece is used for driving the valve rod to rotate; the fixing block is fixedly connected with the valve body, a first threaded hole is formed in the fixing block in a longitudinally penetrating mode, a first external thread in threaded fit with the first threaded hole is formed in the side wall of the valve rod, a valve needle is connected to the bottom end of the valve rod, and the valve needle is used for being matched with the liquid outlet; pressure sensor is fixed in the top of valve rod, and the one end of elastic component is connected with the top of valve rod, and pressure sensor is located in the other end support of elastic component. The invention not only can accurately determine the opening of the liquid outlet by detecting the pressure applied to the liquid outlet by the elastic element by the pressure sensor, but also can determine the rotation direction of the valve rod by the variation trend of the pressure applied to the pressure sensor by the elastic element.

Description

Expansion valve and refrigeration control system

Technical Field

The invention relates to the technical field of valves, in particular to an expansion valve and a refrigeration control system.

Background

An electronic expansion valve is an important component in a refrigeration system and is typically mounted between the reservoir and the evaporator. The medium-temperature high-pressure refrigerant liquid is converted into low-temperature low-pressure refrigerant wet steam after being throttled by the electronic expansion valve, and the refrigerant wet steam absorbs heat in the evaporator to achieve the refrigeration effect. The electronic expansion valve controls the opening of the valve through the change of the superheat degree of the tail end of the evaporator so as to prevent the phenomena of insufficient utilization of the area of the evaporator and cylinder knocking. Most of the existing electronic expansion valves do not have a position feedback function and cannot accurately reflect the opening degree of the valve.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art or the related art. Therefore, the invention provides the expansion valve which has the advantages of simple structure, low cost and high reliability and can accurately reflect the opening degree of the valve.

The invention further provides a refrigeration control system.

An expansion valve according to an embodiment of the first aspect of the present invention includes a pressure sensor, an elastic member, a driving member, a valve body, and a valve rod and a fixing block provided in the valve body; a liquid outlet is formed at the bottom end of the valve body, and a liquid inlet is formed on the side wall of the valve body; the driving piece is used for driving the valve rod to rotate; the fixing block is fixedly connected with the valve body, a first threaded hole is formed in the fixing block in a longitudinally penetrating mode, a first external thread in threaded fit with the first threaded hole is formed in the side wall of the valve rod, a valve needle is connected to the bottom end of the valve rod, and the valve needle is used for being matched with the liquid outlet; the pressure sensor is fixed on the upper portion of the valve rod, one end of the elastic piece is connected with the top end of the valve rod, and the other end of the elastic piece is abutted to the pressure sensor.

According to the expansion valve disclosed by the embodiment of the invention, the opening degree of the liquid outlet can be accurately determined by detecting the pressure applied to the expansion valve by the elastic element by using the pressure sensor, and the rotation direction of the valve rod can also be determined by the change trend of the pressure applied to the pressure sensor by the elastic element.

In addition, the expansion valve according to the embodiment of the present invention may further have the following additional technical features:

according to one embodiment of the invention, the pressure sensor is a piezoelectric pressure sensor, a piezoresistive pressure sensor or a capacitive pressure sensor.

According to one embodiment of the invention, the driving member comprises an armature and a permanent magnet, a second threaded hole is formed in the permanent magnet in a longitudinally penetrating mode, a second external thread in threaded fit with the second threaded hole is formed in the side wall of the valve rod, the armature is sleeved on the outer side of the permanent magnet, and the armature is used for driving the permanent magnet to rotate.

According to one embodiment of the invention, the valve body comprises an upper shell and a lower shell, the top end of the upper shell, the bottom end of the upper shell and the top end of the lower shell are closed ends, the bottom end of the upper shell is fixedly connected with the top end of the lower shell, the bottom end of the lower shell is provided with the liquid outlet, and the side wall of the lower shell is provided with the liquid inlet; the driving piece and the pressure sensor are arranged in the upper shell, and the fixed block is arranged in the lower shell; the top end of the valve rod extends into the upper shell, and the bottom end of the valve rod extends into the lower shell.

According to one embodiment of the present invention, the upper case includes a first threaded sleeve, a second threaded sleeve, a first block piece, a second block piece, and a tab; the first plugging piece is in threaded connection with the top end of the first threaded sleeve, the bottom end of the first threaded sleeve is in threaded connection with the top end of the second threaded sleeve, the second plugging piece is in threaded connection with the bottom end of the second threaded sleeve, and a first through hole for penetrating the valve rod is formed in the second plugging piece in a longitudinally penetrating mode; a step surface is formed on the inner wall of the bottom end of the first threaded sleeve, the lug plate is placed on the end surface of the top end of the second threaded sleeve, and the step surface tightly presses the lug plate; the driving piece is arranged on the second plugging piece, and the lead of the driving piece and the lead of the pressure sensor sequentially penetrate through the lug and the first plugging piece.

According to one embodiment of the invention, the conductors of the driver and the conductors of the pressure sensor are sintered with ceramic at the portions of the lugs.

According to one embodiment of the invention, the lower housing comprises a third threaded sleeve, a third obturating member, a sleeve and an inlet pipe; a second through hole for penetrating the valve rod is formed in the third plugging piece in a longitudinal penetrating mode, the top end of the third plugging piece is fixedly connected with the bottom end of the upper shell, the bottom end of the third plugging piece is in threaded connection with the top end of the third threaded sleeve, and the bottom end of the third threaded sleeve is fixedly sleeved on the top end of the sleeve; the fixed block is fixed in the sleeve, just the liquid outlet with the fixed block sets up relatively, the feed liquor pipe with telescopic lateral wall intercommunication, the feed liquor pipe with the liquid outlet all is located the below of fixed block.

According to one embodiment of the invention, the pressure sensor further comprises an amplifier and a filter, and the pressure sensor is electrically connected with the filter through the amplifier.

According to one embodiment of the invention, the device further comprises a controller and an operation analyzer, wherein the output end of the controller is electrically connected with the driving piece, the input end of the operation analyzer is electrically connected with the filter, and the output end of the operation analyzer is electrically connected with the input end of the controller.

The refrigeration control system according to the second aspect of the embodiment of the invention comprises the expansion valve.

One or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

the valve rod is driven by the driving piece to move up and down when the valve rod rotates, and the pressure applied by the elastic piece to the pressure sensor is increased or reduced along with the valve rod. Therefore, the opening of the liquid outlet can be accurately determined by detecting the pressure applied to the liquid outlet by the elastic element through the pressure sensor, and the rotation direction of the valve rod can be determined through the variation trend of the pressure applied to the pressure sensor by the elastic element.

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

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

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

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

Reference numerals:

100. a drive member; 101. an armature; 102. a permanent magnet; 200. a pressure sensor;

300. a valve stem; 301. a valve needle; 302. an elastic member; 400. a fixed block;

500. an upper housing; 510. a first blocking member; 520. a first threaded sleeve;

530. a second blocking member; 540. a second threaded sleeve; 550. a lug plate;

560. a first seal ring; 600. a lower housing; 601. a liquid inlet; 602. a liquid outlet;

610. a third closure member; 620. a third thread bush; 630. a sleeve; 640. a liquid inlet pipe;

650. a liquid outlet pipe; 660. a second seal ring; 710. an amplifier; 720. a filter;

730. an operation analyzer; 740. and a controller.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. 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.

In the description of the embodiments of the present invention, it should be noted that the terms "longitudinal", "upper", "lower", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only used for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. Specific meanings of the above terms in the embodiments of the present invention can be understood in specific cases by those of ordinary skill in the art.

In embodiments of the invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., 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 an embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to 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. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

As shown in fig. 1, an embodiment of the present invention provides an expansion valve, which includes a pressure sensor 200, an elastic member 302, a driving member 100, a valve body, and a valve rod 300 and a fixing block 400 disposed in the valve body; a liquid outlet 602 is formed at the bottom end of the valve body, and a liquid inlet 601 is formed on the side wall of the valve body; the driving member 100 is used for driving the valve rod 300 to rotate; the fixing block 400 is fixedly connected with the valve body, a first threaded hole is longitudinally formed in the fixing block 400 in a penetrating mode, a first external thread in threaded fit with the first threaded hole is formed in the side wall of the valve rod 300, the bottom end of the valve rod 300 is connected with the valve needle 301, and the valve needle 301 is used for being matched with the liquid outlet 602; the pressure sensor 200 is fixed above the valve rod 300, one end of the elastic element 302 is connected with the top end of the valve rod 300, and the other end of the elastic element 302 abuts against the pressure sensor 200. Wherein the pressure sensor 200 may be, but is not limited to, a piezoelectric pressure sensor, a piezoresistive pressure sensor, or a capacitive pressure sensor; the elastic member 302 may be, but is not limited to, a compression spring.

The following description will be made of the working principle of the expansion valve according to the embodiment of the present invention, taking the application of the expansion valve to a refrigeration system as an example:

during installation, the liquid inlet 601 of the valve body is connected to the outlet of the condenser through a pipeline, and the liquid outlet 602 of the valve body is connected to the inlet of the evaporator through a pipeline. The refrigerant discharged from the condenser flows into the valve body through the liquid inlet 601, and the refrigerant flowing into the valve body flows out of the valve body through the liquid outlet 602 and finally flows into the evaporator through the pipeline.

Because the fixing block 400 longitudinally penetrates and is provided with the first threaded hole, and the side wall of the valve rod 300 is provided with the first external thread in threaded fit with the first threaded hole, when the driving piece 100 drives the valve rod 300 to rotate clockwise, under the threaded fit of the valve rod 300 and the fixing block 400, the valve rod 300 moves downwards relative to the fixing block 400, the valve needle 301 gradually extends into the liquid outlet 602, and then the opening degree of the liquid outlet 602 is reduced. As the opening of the liquid outlet 602 decreases, the flow rate of the liquid flowing out of the valve body through the liquid outlet 602 gradually decreases. During the downward movement of the valve stem 300, the distance between the top end of the valve stem 300 and the pressure sensor 200 increases, the elastic member 302 recovers its deformation, and the pressure applied by the elastic member 302 to the pressure sensor 200 decreases. Similarly, when the driving element 100 drives the valve rod 300 to rotate counterclockwise, the valve rod 300 moves upward relative to the fixed block 400, and the valve needle 301 gradually moves away from the liquid outlet 602, so that the opening degree of the liquid outlet 602 is increased. As the opening of the liquid outlet 602 increases, the flow rate of the liquid out of the valve body through the liquid outlet 602 increases. During the upward movement of the valve stem 300, the distance between the tip end of the valve stem 300 and the pressure sensor 200 decreases, the elastic member 302 is compressed, and the pressure applied by the elastic member 302 to the pressure sensor 200 increases. As can be seen from the above, during the process that the valve rod 300 drives the valve needle 301 to move up and down, the pressure applied by the elastic element 302 to the pressure sensor 200 increases or decreases. Thus, the pressure sensor 200 can determine the opening degree of the liquid outlet 602 by detecting the pressure applied thereto by the elastic member 302. In addition, the rotation direction of the valve stem 300 can also be determined by the trend of the pressure applied to the pressure sensor 200 by the elastic member 302.

As shown in fig. 1, the driving member 100 includes an armature 101 and a permanent magnet 102, a second threaded hole is longitudinally formed through the permanent magnet 102, a second external thread in threaded fit with the second threaded hole is formed on a side wall of the valve rod 300, the armature 101 is sleeved outside the permanent magnet 102, and the armature 101 is used for driving the permanent magnet 102 to rotate. When the armature 101 is energized with three-phase current, the armature 101 generates a rotating magnetic field, which in turn drives the permanent magnet 102 to rotate. Because the permanent magnet 102 longitudinally penetrates through the second threaded hole, and the side wall of the valve rod 300 is provided with a second external thread which is in threaded fit with the second threaded hole, when the permanent magnet 102 rotates, the valve rod 300 rotates relative to the permanent magnet 102 and moves upwards or downwards under the fit of the second threaded hole and the second external thread. Of course, the driving member 100 may also adopt other structural forms, for example, the driving member 100 may directly adopt a motor, the motor is disposed on one side of the valve rod 300, a first bevel gear is fixed on an output shaft of the motor, a second bevel gear meshed with the first bevel gear is sleeved on an outer side of the valve rod 300, a threaded hole is formed in an axis of the second bevel gear, and an external thread in threaded fit with the second bevel gear is formed on a side wall of the valve rod 300. Since the second bevel gear is threadedly coupled to the valve stem 300, the valve stem 300 moves upward or downward relative to the second bevel gear during the rotation of the second bevel gear driven by the motor through the first bevel gear.

As shown in fig. 1, the valve body comprises an upper housing 500 and a lower housing 600, the top end of the upper housing 500, the bottom end of the upper housing 500 and the top end of the lower housing 600 are all closed ends, the bottom end of the upper housing 500 is fixedly connected with the top end of the lower housing 600, a liquid outlet 602 is formed at the bottom end of the lower housing 600, and a liquid inlet 601 is formed at the side wall of the lower housing 600; the driving member 100 and the pressure sensor 200 are disposed in the upper case 500, and the fixing block 400 is disposed in the lower case 600; the top end of the valve stem 300 is inserted into the upper case 500, and the bottom end of the valve stem 300 is inserted into the lower case 600. Wherein the valve stem 300 is integrally formed with the valve needle 301.

Further, the upper case 500 includes a first threaded sleeve 520, a second threaded sleeve 540, a first block piece 510, a second block piece 530, and a tab 550; the first plugging piece 510 is in threaded connection with the top end of the first threaded sleeve 520, the bottom end of the first threaded sleeve 520 is in threaded connection with the top end of the second threaded sleeve 540, the second plugging piece 530 is in threaded connection with the bottom end of the second threaded sleeve 540, and a first through hole for penetrating through the valve rod 300 is formed in the second plugging piece 530 in a longitudinal penetrating mode; a step surface is formed on the inner wall of the bottom end of the first threaded sleeve 520, the lug plate 550 is placed on the end surface of the top end of the second threaded sleeve 540, and the step surface compresses the lug plate 550; the driving member 100 is disposed on the second blocking member 530, and both the conductive wire of the driving member 100 and the conductive wire of the pressure sensor 200 sequentially pass through the wire connecting piece 550 and the first blocking member 510. To improve the sealing effect, the wires of the driver 100 and the wires of the pressure sensor 200 are sintered with ceramic at the portions of the terminal strips 550.

In addition, in order to improve the sealing performance between the top end surface of the second thread bushing 540 and the lug 550, a first sealing ring 560 is installed between the top end surface of the second thread bushing 540 and the lug 550, specifically, a first annular groove is formed in the top end surface of the second thread bushing 540, and the first sealing ring 560 is embedded in the first annular groove.

As shown in fig. 1, the lower housing 600 includes a third threaded sleeve 620, a third plugging member 610, a sleeve 630 and an inlet pipe 640; a second through hole for penetrating the valve rod 300 is longitudinally formed in the third plugging member 610 in a penetrating manner, the top end of the third plugging member 610 is fixedly connected with the bottom end of the upper shell 500, the bottom end of the third plugging member 610 is in threaded connection with the top end of the third threaded sleeve 620, and the bottom end of the third threaded sleeve 620 is fixedly sleeved on the top end of the sleeve 630; the fixed block 400 is fixed in the sleeve 630, the liquid outlet 602 is opposite to the fixed block 400, the liquid inlet pipe 640 is communicated with the side wall of the sleeve 630, and the liquid inlet pipe 640 and the liquid outlet 602 are both located below the fixed block 400. Further, the valve body further comprises a liquid outlet pipe 650, one end of the liquid outlet pipe 650 is communicated with the liquid outlet 602, and the other end of the liquid outlet pipe 650 extends downwards. Similarly, in order to improve the sealing performance between the top end face of the sleeve 630 and the third plugging member 610, a second sealing ring 660 is installed between the top end face of the sleeve 630 and the third plugging member 610, specifically, a second annular groove is formed in the top end face of the sleeve 630, and the second sealing ring 660 is embedded in the second annular groove.

Further, as shown in fig. 1 and fig. 2, the expansion valve further includes an amplifier 710 and a filter 720, and the pressure sensor 200 is electrically connected to the filter 720 through the amplifier 710. Further, in order to realize closed-loop control, the expansion valve further comprises a controller 740 and an operation analyzer 730, wherein an output end of the controller 740 is electrically connected with the driving member 100, an input end of the operation analyzer 730 is electrically connected with the filter 720, and an output end of the operation analyzer 730 is electrically connected with an input end of the controller 740. Still further, the expansion valve may further include an alarm electrically connected to the controller 740. The alarm may be, but is not limited to, a buzzer or a warning light.

Taking the example of the expansion valve applied to the refrigeration system in the embodiment of the present invention as an example, the controller 740 sends a driving signal to the driving member 100 according to the actual required refrigeration capacity received from the refrigeration system, so that the driving member 100 drives the valve rod 300 to rotate, and the valve rod 300 moves downward or upward through the threaded fit with the fixed block 400, so that the elastic member 302 applies a specified pressure to the pressure sensor 200. The pressure sensor 200 amplifies the detected pressure signal through the amplifier 710, filters the signal through the filter 720, and inputs the amplified signal to the operation analyzer 730, the operation analyzer 730 determines the deviation between the actual pressure and the designated pressure of the pressure sensor 200, and the controller 740 controls the driving member 100 to operate according to the deviation fed back by the operation analyzer 730 to eliminate the deviation. When the variation trend of the pressure detected by the pressure sensor 200 is wrong, it indicates that the rotation direction of the valve rod 300 is wrong, and the controller 740 controls the alarm to give an alarm. It should be noted that the controller 740 may pre-store a comparison table of the relationship between the cooling capacity and the pressure applied to the pressure sensor 200, or may pre-store a relationship between the cooling capacity and the pressure applied to the pressure sensor 200. In addition, the controller 740 may also pre-store a relation table or a relation between the pressure applied to the pressure sensor 200 and the opening of the liquid outlet 602.

In addition, the embodiment of the invention also provides a refrigeration control system, which comprises the expansion valve.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the invention, but not to limit it; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An expansion valve is characterized by comprising a pressure sensor, an elastic part, a driving part, a valve body, a valve rod and a fixed block, wherein the valve rod and the fixed block are arranged in the valve body; a liquid outlet is formed at the bottom end of the valve body, and a liquid inlet is formed on the side wall of the valve body; the driving piece is used for driving the valve rod to rotate; the fixing block is fixedly connected with the valve body, a first threaded hole is formed in the fixing block in a longitudinally penetrating mode, a first external thread in threaded fit with the first threaded hole is formed in the side wall of the valve rod, a valve needle is connected to the bottom end of the valve rod, and the valve needle is used for being matched with the liquid outlet; the pressure sensor is fixed on the upper portion of the valve rod, one end of the elastic piece is connected with the top end of the valve rod, and the other end of the elastic piece is abutted to the pressure sensor.

2. An expansion valve according to claim 1, wherein the pressure sensor is a piezo-electric pressure sensor, a piezo-resistive pressure sensor or a capacitive pressure sensor.

3. An expansion valve according to claim 1, wherein the driving member comprises an armature and a permanent magnet, wherein a second threaded hole is formed in the permanent magnet in a longitudinal direction, a second external thread which is in threaded fit with the second threaded hole is formed on a side wall of the valve rod, the armature is sleeved on an outer side of the permanent magnet, and the armature is used for driving the permanent magnet to rotate.

4. The expansion valve according to claim 1, wherein the valve body comprises an upper housing and a lower housing, the top end of the upper housing, the bottom end of the upper housing and the top end of the lower housing are closed ends, the bottom end of the upper housing is fixedly connected with the top end of the lower housing, the bottom end of the lower housing is formed with the liquid outlet, and the side wall of the lower housing is formed with the liquid inlet; the driving piece and the pressure sensor are arranged in the upper shell, and the fixed block is arranged in the lower shell; the top end of the valve rod extends into the upper shell, and the bottom end of the valve rod extends into the lower shell.

5. The expansion valve of claim 4, wherein the upper housing comprises a first threaded sleeve, a second threaded sleeve, a first block piece, a second block piece, and a lug; the first plugging piece is in threaded connection with the top end of the first threaded sleeve, the bottom end of the first threaded sleeve is in threaded connection with the top end of the second threaded sleeve, the second plugging piece is in threaded connection with the bottom end of the second threaded sleeve, and a first through hole for penetrating the valve rod is formed in the second plugging piece in a longitudinally penetrating mode; a step surface is formed on the inner wall of the bottom end of the first threaded sleeve, the lug plate is placed on the end surface of the top end of the second threaded sleeve, and the step surface tightly presses the lug plate; the driving piece is arranged on the second plugging piece, and the lead of the driving piece and the lead of the pressure sensor sequentially penetrate through the lug and the first plugging piece.

6. An expansion valve according to claim 5, wherein the leads of the driver and the pressure sensor are sintered with ceramic at the portions of the terminal strips.

7. An expansion valve according to claim 4, wherein the lower housing comprises a third threaded sleeve, a third closure, a sleeve and a liquid inlet pipe; a second through hole for penetrating the valve rod is formed in the third plugging piece in a longitudinal penetrating mode, the top end of the third plugging piece is fixedly connected with the bottom end of the upper shell, the bottom end of the third plugging piece is in threaded connection with the top end of the third threaded sleeve, and the bottom end of the third threaded sleeve is fixedly sleeved on the top end of the sleeve; the fixed block is fixed in the sleeve, just the liquid outlet with the fixed block sets up relatively, the feed liquor pipe with telescopic lateral wall intercommunication, the feed liquor pipe with the liquid outlet all is located the below of fixed block.

8. An expansion valve according to any of claims 1-7, further comprising an amplifier and a filter, the pressure sensor being electrically connected to the filter via the amplifier.

9. An expansion valve according to claim 8, further comprising a controller and an arithmetic analyzer, an output of the controller being electrically connected to the drive member, an input of the arithmetic analyzer being electrically connected to the filter, an output of the arithmetic analyzer being electrically connected to an input of the controller.

10. A refrigeration control system comprising an expansion valve according to any of claims 1 to 9.