Patent Publication Number: US-2022221078-A1

Title: Nut assembly for electronic expansion valve, electronic expansion valve, and limiting element mounting method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage application of International Application No. PCT/CN2020/089503 filed on May 10, 2020, which claims all benefits accruing under 35 U.S.C. § 119 from China Patent Application Nos. 201910389712.X, filed on May 10, 2019, 201911151362.X, filed on Nov. 21, 2019, and 201920667717.X, filed on May 10, 2019, in the China National Intellectual Property Administration, the content of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of electronic expansion valve, and in particular to a nut assembly of an electronic expansion valve, an electronic expansion valve, and a method for mounting a limiting element. 
     BACKGROUND 
     An electronic expansion valve includes a rotator assembly, a nut assembly, a valve needle assembly, and a valve base. The valve base is provided with a valve port. The rotator assembly is configured for driving the valve needle assembly to move, so as to control the valve port to open. The nut assembly includes a nut base, an elastic member and a check ring. The check ring can move along a direction of an axis of the nut base on the elastic member. When the check ring moves to a top or a bottom of the elastic member, the check ring abuts against the elastic member to realize upper backstop and lower backstop, so as to limit the number of rotating of the rotator assembly. 
     However, when the check ring abuts against the elastic member, the elastic member can deform easily due to elasticity of the elastic member, causing inaccurate positioning. 
     SUMMARY 
     On the basis of embodiments of the present disclosure, the present disclosure provides a nut assembly of an electronic expansion valve, an electronic expansion valve, and a method for mounting a limiting element 
     A nut assembly of an electronic expansion valve, including: a nut base having a first end and a second end opposite to each other; a stop guide rail sleeved on the nut seat; a check ring sleeved on the nut seat sleeved on the nut seat, which is configured to spirally rotate relative to the nut base along the stop guide rail; and, a limiting element disposed at the first end of the nut base, which is configured to limit movement of the stop guide rail along an axis of the nut base on the nut base, and to limit rotation of the check ring. 
     An electronic expansion valve including a nut assembly. 
     A method for mounting the limiting element which includes: 
     sleeving the limiting element on the nut base and making the second limiting protrusion inserting into the first limiting groove though the notch of the first limiting groove; 
     and 
     rotating the limiting element to make the second limiting protrusion sliding into the corresponding second limiting groove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For one of ordinary skill in the art, other drawings can be obtained from these drawings without creative work. 
         FIG. 1  is an explosive view of a nut assembly in a first embodiment of the present disclosure. 
         FIG. 2  is another explosive view of a nut assembly in the first embodiment of the present disclosure. 
         FIG. 3  is an explosive view of another structure of a nut assembly in the first embodiment of the present disclosure. 
         FIG. 4  is a structural schematic diagram of a limiting element in an initial state in the first embodiment of the present disclosure. 
         FIG. 5  is another structural schematic diagram of a limiting element in an initial state in the first embodiment of the present disclosure. 
         FIG. 6  is a structural schematic diagram of a limiting element at a limiting state in the first embodiment of the present disclosure. 
         FIG. 7  is another structural schematic diagram of a limiting element in an initial state in the first embodiment of the present disclosure. 
         FIG. 8  is a structural schematic diagram of a limiting element in  FIG. 1 . 
         FIG. 9  is a structural schematic diagram of a limiting element in  FIG. 3 . 
         FIG. 10  is a top view of a limiting element in an initial state in the first embodiment of the present disclosure. 
         FIG. 11  is a top view of a limiting element in a limiting state in the first embodiment of the present disclosure. 
         FIG. 12  is a structural schematic diagram of a nut base in  FIG. 1 . 
         FIG. 13  is a partial enlarged diagram at portion A of  FIG. 12 . 
         FIG. 14  is a structural schematic diagram of a nut assembly in a first embodiment of the present disclosure. 
         FIG. 15  is a partial enlarged diagram at portion B of  FIG. 14 . 
         FIG. 16  is a cross-section view of a nut assembly in the first embodiment of the present disclosure. 
         FIG. 17  is a structural schematic diagram of a nut assembly in a second embodiment of the present disclosure. 
         FIG. 18  is a partial enlarged diagram at portion C of  FIG. 17 . 
         FIG. 19  is another structural schematic diagram of a nut assembly in embodiment 2 of the present disclosure. 
         FIG. 20  is a structural schematic diagram of a limiting element in  FIG. 18 . 
         FIG. 21  is a structural schematic diagram of a stop guide rail in  FIG. 18 . 
         FIG. 22  is a structural schematic diagram of a nut assembly in a third embodiment of the present disclosure. 
         FIG. 23  is a structural schematic diagram of a nut assembly in a fourth embodiment of the present disclosure. 
         FIG. 24  is a structural schematic diagram of an electronica expansion valve of the present disclosure. 
         10  represents a nut base;  11  represents a first end of a nut base;  12  represents a second end of a nut base;  13  represents a base;  131  represents a connecting groove;  14  represents a mandrel;  141  represents a first limiting protrusion;  15  represents a first limiting groove;  16  represents a second limiting groove;  17  represents a recessing groove;  18  represents a third limiting groove;  19  represents a stopping protrusion;  101  represents a limiting hole;  111  represents a mounting portion;  1111  represents a mounting groove;  1112  represents a second rib;  20  represents a stop guide rail;  21  represents a third end of the stop guide rail;  22  represents a fourth end of the stop guide rail;  23  represents a first bending section;  30  represents a check ring;  31  represents a stopping portion;  40  represents a limiting element;  41  represents a limiting portion;  411  represents a first plane;  412  represents a second plane;  413  represents a notch;  414  represents a first rib;  42  represents a second limiting protrusion;  43  represents a third limiting protrusion;  50  represents a valve assembly;  60  represents a rotator assembly;  70  represents a valve seat. 
     
    
    
     DETAILED DESCRIPTION 
     The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by one of ordinary skill in the art without creative work are within the scope of protection of this disclosure. 
     It should be noted that when a component is referred to as being “arranged on” another component, it can be directly on the other component or a central component may also exist. When a component is considered to be “disposed on” another component, it can be directly installed on another component or a centered component may exist at the same time. When a component is considered to be “fixed” to another component, it can be directly fixed to the other component or there may be a centered component at the same time. 
     It should be noted that in the description of the present disclosure, the orientation or positional relationship indicated by the involved orientation words such as “front, back, up, down, left, right”, “horizontal, vertical, perpendicular, horizontal” and “top, bottom” are usually based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the disclosure and simplifying the description. Unless otherwise stated, these orientation words do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the protection scope of the present disclosure. The orientation words “inner and outer” refer to the inner and outer parts relative to the contour of each component itself. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art of this disclosure. The terminology used in the specification of the disclosure herein is only for the purpose of describing specific embodiments, and is not intended to limit the disclosure. The term “or/and” as used herein includes any and all combinations of one or more related listed items. 
     Referring to  FIG. 1  to  FIG. 16 , a first embodiment of the present disclosure provides a nut assembly, which can include a nut base  10 , a stop guide rail  20 , a check ring  30  and a limiting element  40 . Both the stop guide rail  20  and the check ring  30  can be sleeved on the nut base  10 . The stop guide rail  20  can be a slide rail to lead the check ring  30  moving along the stop guide rail  20 , so that the check ring  30  can spirally rotate relative to the nut base  10  along the stop guide rail  20 . The limiting element  40  can be disposed on the nut base  10 , which can be configured to limit a position of the stop guide rail  20  on the nut base  10  along an axis of the nut base  10 , so as to prevent the stop guide rail  20  from falling off from the nut base  10 , and can be configured to limit rotation of the check ring  30 . 
     The nut base  10  can have a first end  11  and a second end  12  opposite to each other. The limiting element  40  can be disposed at the first end  11  of the nut base  10 . 
     The nut base  10  can include a base  13  and a mandrel  14 . The base  13  can be mounted on the mandrel  14 , and the mandrel  14  can be in a cylinder shape. Both the stop guide rail  20  and the check ring  30  can be sleeved on the mandrel  14 . An end of the mandrel  14  away from the base  13  can be defined as the first end of the nut base  10 , and an end of the base  13  away from the mandrel  14  can be defined as the second end of the nut base  10 . 
     The stop guide rail  20  can have a third end  21  and a fourth end  22  opposite to each other. The limiting element  40  can be provided with a limiting portion  41 . By penetrating the third end  21  of the stop guide rail  20  through the limiting portion  41 , the limiting portion  41  can limit displacement of the third end  21  of the stop guide rail  20  along the axis of the nut base  10 , and the third end  21  of the stop guide rail  20  is free in circumferential direction of the nut base  10 . 
     In some embodiments, the stop guide rail  20  can be an elastic member. In some embodiments, the elastic member can be a spring or other members having elasticity. 
     In some embodiments, the check ring  30  can be provided with a stopping portion  31 . The limiting portion  41  can cooperate with the stopping portion  31  to limit and stop the check ring  30 . That is, the stopping portion  31  can cooperate with the limiting portion  41  to limit rotation of the check ring  30 . At this time, the stop guide rail  20  only plays a role of guide rail, and the stop guide rail  20  will not deform, thereby promoting positioning accuracy. 
     In a nut assembly of the present embodiment, by penetrating the third end  21  of the stop guide rail  20  on the limiting portion  41 , the limiting portion  41  can limit displacement of the third end  21  of the stop guide rail  20  along the axis of the nut base  10 , and the third end  21  of the stop guide rail  20  can be free in the circumferential direction of the nut base  10 . Using the above structure, when the limiting portion  41  cooperates with the stopping portion  31  to stop and limit the check ring  30 , the stop guide rail  20  merely plays a role of slide rail. The stop guide rail  20  will not deform, facilitates processing, and can limit the check ring  30  while improving positioning accuracy. In addition, since backstop is hard stop, the backstop position is more accurate, and an initial position of the electronic expansion valve is more accurate. 
     The limiting element  40  can stop and limit the check ring  30 , including stopping and limiting the limiting element  40  at the top and the bottom. By disposing the limiting element  40  on the nut base  10  at a position near the first end  11  or near the second end  12 , the limiting element  40  can stop and limit the check ring at the top or the bottom. By contemporarily disposing the limiting elements  40  on the nut base  10  at positions near the upper end and the lower end of the nut base  10 , the limiting element  40  can stop and limit the check ring  30  at the top and the bottom. 
     In some embodiments, referring to  FIG. 5  or  FIG. 7 , the check ring  30  can be stopped and limited at the top and the bottom by other methods, and is not restricted to the limiting element  40 . For example, the nut base  10  can be provided with corresponding stopping protrusion  19 , and the check ring  30  can cooperate with the stopping protrusion  19  to stop and limit the check ring  30  at the top and the bottom. 
     Specifically, the limiting portion  41  has a first plane  411 . When the check ring  30  rotates to an end of the stop guide rail near the limiting element  40 , the stopping portion  31  can abut against the first plane  411 , so that the limiting element  40  can stop and limit the check ring along the circumferential direction. 
     In the present embodiment, the limiting element  40  can be in a ring shape. By sleeving the limiting element  40  on the first end of the nut base  10 , the third end  21  of the stop guide rail  20  can abut against a surface of the limiting element  40  near the nut base  10 , so that the limiting element  40  can limit a position of the stop guide rail  20  on the nut base  10  along the axis of the nut base  10 . 
     The limiting portion  41  can further have a second plane  412  perpendicular to the first plane  411 , and the third end  21  of the stop guide rail  20  can abut against the second plane  412 , so that the limiting portion  41  can limit a position of the guide rail  20  along the axis of the nut base  10 , thereby preventing the stop guide rail  20  from separating from the nut base  10 . 
     It should be understood that the third end  21  of the stop guide rail  20  can abut against the second plane  412 , and the fourth end  22  can abut against the stopping protrusion  19  or the limiting element  40 . Therefore, when the first plane  411  stops the check ring  30  rotating, the check ring  30  will not contact the stop guide rail  20 . That is, a top end of the stop guide rail  20  will not suffer from a stopping force, and the limiting element  40  can suffer independently from the stopping force. The stop guide rail  20  cannot deform, so that the stop guide rail  20  will not influence sliding of the check ring  30 . At the same time, the limiting element  40  is an inelastic member, and will not cause stopping resilience, thereby increasing reliability. In addition, the third end  21  of the stop guide rail  20  does not have a special structure, which is simple to process, and has a size easy to be controlled. 
     The limiting portion  41  can protrude out from an end of the limiting element  40  near the nut base  10 . There is an interval between a part of the limiting portion  41  protruding out from the limiting element  40  near the nut base  10  and the out wall of the nut base  10 , which facilitates the third end  21  of the stop guide rail  20  penetrating through the interval, so that the limiting portion  41  can limit displacement of the third end  21  of the stop guide rail  20  along the axis of the nut base  10 . 
     In some embodiments, a notch  413  can be located on a side of the limiting portion  41  towards the nut base  10 , and the third end  21  of the stop guide rail  20  can penetrate through the notch  413 . In some embodiments, the notch  413  can be located at an end of the limiting portion  41 . 
     In order to improve fitting effect between the limiting portion  41  and the stop guide rail  20 , and prevent the limiting portion  41  from limiting displacement of the stop guide rail  20  along a circumferential direction of the nut base  10 , a shape and a size of the notch  413  can match with a shape and a size of the end of the stop guide rail  20 , respectively. In some embodiments, an inner wall of the notch  413  can be a hook surface. 
     At the same time, the inner wall of the notch  413  can replace the second plane  412 . The third end  21  of the stop guide rail  20  can cooperate with the inner wall of the notch  413  to limit a position of the stop guide rail  20  along the axis of the nut base  10 . 
     In order to prevent the limiting element  40  from falling off from the nut base  10 , a first limiting structure can be disposed between the limiting element  40  and the nut base  10 , and the first limiting structure can be configured to limit movement of the limiting element  40  along the axis of the nut base  10 . The first limiting structure can include such a structure including a protrusion and a groove matching with each other, or a dowel limiting structure, or a fastener limiting structure. 
     The limiting element  40  can be in an initial state and in a limiting state, and the limiting element  40  can rotate relative to the nut base  10 , so that the limiting element  40  can move between the initial position and the limiting position. When the limiting element  40  is in the initial state, the limiting element  40  can move towards the nut base  10  along the axis of the nut base  10 . When the limiting element  40  is located at the limiting position, the limiting element  40  cannot move towards the nut base  10  along the axis of the nut base  10 . Therefore, the limiting element  40  will not fall off from the nut base  10 . In the present embodiment, when rotating the limiting element  40 , a rotation direction of the limiting element  40  is in accordance with the direction of the up backstop. 
     Specifically, in order to limit the limiting element  40  along the axis of the nut base  10 , the first end  11  of the nut base  10  can be provided with a first limiting groove  15  and a second limiting groove  16  communicating with each other. A notch of the first limiting groove  15  can be located at an end surface of the first end  11  of the nut base  10 , and a notch of the second limiting groove  16  can be located at a side of the first end  11  of the nut base  10 . In other words, a first limiting protrusion  141  can be disposed on the wall of the first limiting groove  15 , and there is an interval between the first limiting protrusion  141  and a bottom of the first limiting groove  15 . A second limiting protrusion  42  can be disposed on the inner wall of the limiting element  40 . When the limiting element  40  is in the initial state, the second limiting protrusion  42  can be disposed corresponding to the notch of the first limiting groove  15 . At this time, the second limiting protrusion  42  can be accommodated in the first limiting groove  15 . When the limiting element  40  is in the limiting state, the second limiting protrusion  42  can move to the second limiting groove  16 , i.e., moving to a place between the first limiting protrusion  141  and the bottom of the groove. At this time, movement of the limiting element  40  along the axis of the nut base  10  can be limited by cooperation of the first limiting protrusion  141  and the second limiting groove  16  or the second limiting protrusion  42 , so as to fix the limiting element  40  in the direction of the axis of the nut base  10 . 
     In the present embodiment, an upper surface of the first limiting protrusion  141  can be parallel to an end surface of the first end  11  of the nut base  10 . Therefore, the nut base  10  can be integrated, which facilitates processing the nut base  10 . In addition, the second limiting protrusion  42  can be disposed at a lower side of an inner wall of the limiting element  40 . 
     When the limiting element  40  is in the limiting state, the stop guide rail  20  can abut against a surface of the limiting element  40  near the stop guide rail  20 , and the stop guide rail  20  can be in a compression state at this time. That is, when the limiting element  40  rotates, the second plane  412  can abut against the third end  21  of the stop guide rail  20  from beginning to end. Therefore, under elastic force of the stop guide rail  20 , the first limiting protrusion  141  can abut against the second limiting protrusion  42 , and can further improve the limiting effect of the limiting element  40  along the axis of the limiting element  40 . 
     Specifically, when the limiting element  40  is in the limiting state, the upper surface of the limiting element  40  can be parallel to the end surface of the first end  11  of the nut base  10 . Therefore, the nut base  10  can be integrated, and avoid blocking the assembly and working of other parts. 
     The stop guide rail  20  can be in free state and extend without the limiting element  40 . At this time, a height of the stop guide rail  20  can be larger than or equals to a height of the stop guide rail  20  after the limiting element  40  is mounted on the nut base  10 . When the limiting element  40  is mounted on the nut base  10  and in the limiting state, the first end of the stop guide rail  20  can be located in the limiting portion  41  and the stop guide rail  20  can be in the compression state. The stop guide rail  20  can supply elastic force on the limiting element  40 , and can reduce risk of sliding of the limiting element  40  caused by vibration. 
     In the present embodiment, a side wall of the nut base  10  can be provided with a plurality of the first limiting grooves  15 . The plurality of first limiting grooves  14  can be annularly disposed on the side wall of the nut base  10 . A plurality of second limiting protrusions  42  can be disposed on the inner wall of the limiting element  40 , and the plurality of first limiting grooves  15  can be disposed corresponding to the plurality of second limiting protrusions  42 , thereby further improving limiting effect. In the present embodiment, the side wall of the nut base  10  can be provided with two first limiting grooves  15 , and the inner wall of the limiting element  40  can be provided with two second limiting protrusions  42 . 
     At the same time, the number of the second limiting grooves can be a plurality. A plurality of second limiting grooves  16  can be correspondingly disposed to the plurality of first limiting grooves  15 , respectively. The plurality of second limiting grooves  16  can be perpendicular to the plurality of first limiting grooves  15  to define an L-shaped positioning groove. 
     In some embodiments, the plurality of first limiting grooves  15  can be non-central symmetrically disposed. The nut base  10  can have advantages of high strength of stress and anti-warping. In some embodiments, the plurality of first limiting grooves  15  can be uniformly disposed on the side wall of the nut base  10 . 
     In the present embodiment, a second limiting structure can be disposed between the limiting element  40  and the nut base  10 , and can be configured to limit the limiting element  40  to rotate relative to the nut base  10 . The second limiting structure can include a protrusion and a structure matching with the limiting groove, or a dowel limiting structure, or a fastener limiting structure. 
     Specifically, the out wall of the nut base  10  can be provided with a recessing groove  17  and a third limiting groove  18 , and the recessing groove  17  and the third limiting groove  18  can be disposed at intervals. By disposing the third limiting protrusion  43  on the inner wall of the limiting element  40 , when the limiting element  40  is in the initial state, the third limiting protrusion  43  can be disposed correspondingly to the recessing groove  17 . And, when the limiting element  40  is in the limiting state, the third limiting protrusion  43  can move from the recessing groove  17  into the third limiting groove  18 , and the third limiting protrusion  43  can cooperate with the third limiting groove  18  to limit rotation of the limiting element  40 , so as to fix the limiting element  40  circumferentially. In addition, while sleeving the limiting element  40  on the nut base  10 , the recessing groove  17  and the third limiting protrusion  43  can play a role of guiding. In the present embodiment, the limiting element  40  can be made of a rigid material. Since the limiting element  40  is in a ring shape, when the limiting element  40  is sleeved on the nut base  10  and rotating, the limiting element  40  can slightly deform, so that the third limiting protrusion  43  can move into the third limiting groove  18 . 
     In the present embodiment, both the recessing groove  17  and the third limiting groove  18  can extend along the axis of the nut base  10 . Both a notch of the recessing groove  17  and a notch of the third limiting groove  18  can be located on the upper surface of the nut base  10 , so as to facilitate sleeving the limiting element  40  on the nut base  10 . 
     A shape of cross-section of the third limiting groove  18  can include semicircle, U-shape and triangle. Besides, a shape and a size of the third limiting protrusion  43  can match with a shape and a size of the third limiting groove  18 , respectively. In the present embodiment, a cross-section of the third limiting groove  18  can be in a semicircle shape. 
     In the present embodiment, a side wall of the recessing groove  17  near the third limiting groove  18  can be a hook surface, so as to facilitate the third limiting protrusion  43  rotating from the recessing groove  17  to the third limiting groove  18 . 
     In order to further improve limiting effect to the limiting element  40 , a plurality of recessing grooves  17  and a plurality of third limiting grooves  18  can be disposed on the outer wall of the nut base  10 . A plurality of third limiting protrusions  43  can be disposed on the inner wall of the limiting element  40 , and each of the plurality of third limiting protrusions  43  can be disposed correspondingly to one of the plurality of recessing grooves  17  and one of the plurality of third limiting grooves  18 . 
     In the present embodiment, a material of the limiting element can include nonmetal materials. Since the check ring  30  is spring steel wire, the nonmetal material hits against the metal, noise can be reduced. 
     In addition, since the stop guide rail  20  is free from the stopping force, a wire diameter of the stop guide rail  20  can be reduced. Therefore, by adjusting circles of the stop guide rail  20 , a number of rotating of a rotator can be adjusted. That is, moving distance of a valve needle of the electronic expansion valve can be adjusted, and precision of flow rate can be adjusted. In addition, the stop guide rail  20  is simple to process, and has a size easy to be controlled. 
     In the present embodiment, the fourth end  22  of the stop guide rail  20  can have a first bending section  23 . The first bending section  23  can bend along the axis of the stop guide rail  20 . The nut base  10  can be provided with a limiting hole  101 . The first bending section  23  can insert towards the limiting hole  101 , so as to limit circumferential rotation of the stop guide rail  20 . The mounting portion  111  of the nut base  10  can cooperate with the other end away from the stooping portion  31  of the check ring, to stop and limit the check ring  30  at the top and the bottom. A balancing hole can be a limiting hole. Therefore, the balancing hole not only can quickly balance pressure in the valve chamber and the nut base  10 , but can also limit the fourth end of the stop guide rail  20  by the balancing hole. 
     In other embodiments, an end of the base  13  away from the mandrel  14  can be provided with a connecting groove  131 , and a first bending section  23  can be fixed in the connecting groove  13 , so as to fix the stop guide rail  20  on the mandrel  14 , preventing the stop guide rail  20  from moving along with rotation of the check ring  30 . In the present embodiment, the end of the base  13  away from the mandrel  14  can be integrally produced. 
     Specifically, the check ring  30  can have a second bending section. The second bending section can bend towards a direction away from the nut base  10 , and the second bending section can define the stopping portion  31 . 
     In some embodiments, the check ring  30  can be reversely mounted. The stopping portion  31  can cooperate with the mounting portion  111  of the nut base  10  to realize upper backstop and lower backstop. The end of the check ring  30  away from the stopping portion  31  can cooperate with the limiting portion  41  of the limiting element  40  to realize upper backstop and lower backstop. 
     Referring to  FIG. 17  and  FIG. 21 , a nut assembly is provided in a second embodiment of the present disclosure. Compared with the nut assembly in the first embodiment 1, both ends of the stop guide rail  20  can be provided with a bending section. Both a limiting portion  41  of the limiting element  40  and the nut base  10  can be provided with a mounting structure. The stop guide rail  20  can be mounted and fixed by the mounting structure to limit rotation of the stop guide rail relative to the nut base  10 . The mounting structure can include mounting structures such as a matching structure having a groove and a rib, a dowel, a bolt and the like. 
     Specifically, a first rib  414  can be disposed at an end of the notch  413  of the limiting portion  41 , and the first rib  414  can be disposed opposite to the third end of the stop guide rail  20 . The stop guide rail  20  can be sleeved on the nut base  10 . When the limiting element  40  is mounted on the nut base  10 , the third end of the stop guide rail  20  can abut against the first rib  414 , so as to limit the third end of the stop guide rail  20  along circumference of the nut base  10 . 
     In addition, the nut base  10  can be provided with a mounting portion  111 . The mounting portion  111  can be configured to limit the fourth end  22  of the stop guide rail  20  along circumference of the nut base  10 . A mounting groove  1111  can be disposed at one side of the mounting portion  111  towards the nut base  10 , and the fourth end  22  of the stop guide rail  20  can penetrate through the mounting groove  1111 . Specifically, an end of the mounting groove  1111  can be provided with a second rib  1112 , and the second rib  1112  can be disposed opposite to the end of the fourth end  22  of the stop guide rail  20 . After sleeving the stop guide rail  20  on the nut base  10 , the fourth end  22  of the stop guide rail  20  can be locate in the mounting groove  1111 , and the end of the fourth end  22  of the stop guide rail can abut against the second rib  1112 , so as to limit the second end of the stop guide rail  20  along circumference of the nut base  10 . 
     Referring to  FIG. 22 , a nut assembly is provided in a third embodiment of the present disclosure. Compared with the nut assembly in embodiment 1, a detachable limiting element  40  can be disposed on the nut base  10  near the second end  12  of the nut base in embodiment 3, and the limiting portion  41  in the limiting element  40  can stop and limit the check ring at the top and the bottom. 
     The limiting element  40  can be in a ring shape. The limiting element  40  can be sleeved on the nut base  10  at a position near the lower end of the nut base. The limiting element  40  can be provided with a limiting portion  41 , and the limiting portion  41  can be disposed towards the stop guide rail  20 . 
     Specifically, an accommodating groove can be disposed on the upper surface of the limiting portion  41  near the axis of the nut base  10 . The stop guide rail  20  can be accommodated in the accommodating groove. The limiting portion  41  can limit the stop guide rail  20  in a radial direction of the nut base  10 . In addition, by disposing the accommodating groove on the upper surface of the limiting portion  41 , the height of the limiting portion  41  can be increased, so that reliability of up backstop and down backstop can be further ensured, thereby avoiding slippage of backstop. In addition, the limiting element  40  can support the stop guide rail  20 , so that position of the stop guide rail  20  along the axis of the nut base  10  can be limited. 
     Referring to  FIG. 23 , a nut assembly is provided in a fourth embodiment of the present disclosure. Compared with the nut assembly in embodiment 1, a position on the nut base  10  near the bottom part of the nut base  10  in embodiment 4 can be provided with a detachable limiting element  40 , and the limiting element  40  can stop and limit the check ring  30  at top and bottom. 
     The limiting element  40  can be a limiting block, the limiting element  40  can be inserted on the nut base  10 , and the limiting element  40  and the limiting portion  41  can be disposed towards the stop guide rail  20 . 
     Specifically, an accommodating groove can be disposed on the upper surface of the limiting portion  41  near the axis of the nut base  10 . The stop guide rail  20  can be accommodated in the accommodating groove. The limiting portion  41  can limit the stop guide rail  20  in a radial direction of the nut base  10 . In addition, by disposing the accommodating groove on the upper surface of the limiting portion  41 , the height of the limiting portion  41  can be increased, so that reliability of up backstop and down backstop can be further ensured, thereby avoiding slippage of backstop. In addition, the limiting element  40  can support the stop guide rail  20 , so that position of the stop guide rail  20  along the axis of the nut base  10  can be limited. 
     In some embodiments, an accommodating groove on the limiting portion  41  disposed near a lower end of the nut base  10  can be provided with a rib, so as to limit the stop guide rail  20  in the radial direction and circumferential direction of the nut base  10 . 
     Referring to  FIG. 24 , the present disclosure provides an electronic expansion valve, which can include the nut assembly described above. 
     The electronic expansion can include a rotator assembly  60 , a valve assembly  50  and a valve seat  70 . The valve seat  70  can be provided with a valve port. The rotator assembly  60  can be configured for driving the valve assembly  50  to move to control lockage and opening of the valve port. Specifically, the rotator assembly can include a rotator and a stirring member. An end of the stirring member is connected to the rotator, and the other end of the stirring member is connected to the check ring  30 . When the rotator rotates, the rotator can drive the check ring  30  to move along the axis of the nut base  10  via the stirring member. The check ring  30  can cooperate with the limiting portion  41  of the limiting element  40  to carry out up backstop, and the check ring  30  can cooperate with the mounting portion  111  of the nut base  10  to carry out down backstop. 
     The device of the present embodiment includes the following benefits. 
     (1) A limiting portion  41  can be disposed on the limiting element  40 , and can prevent the first end of the stop guide rail  20  from popping out. When the limiting element  40  is mounted on the nut base  10 , a pretightening force can be increased by spinning the limiting element  40 . 
     (2) Relying on pretightening force of the stop guide rail  20 , a stop guide rail  20  can cooperate with the nut base  10  and the limiting element  40  to carry out limitation along the axis of the nut base  10 . 
     (3) The limiting element  40  can be provided with a third limiting protrusion. The third limiting protrusion  43  can cooperate with the third limiting groove  18  to limit rotation of the limiting element  40  relative to the nut base  10 , so as to prevent falling off of the device caused by vibration. 
     (4) A plurality of first limiting grooves  15  can be non-central symmetrically disposed. The nut base can have advantages of high strength of stress and anti-warping. 
     (5) The limiting hole  101  on the nut base  10  can contemporarily play a role of balancing hole, which can realize fixation of the fourth end  22  of the stop rail  20  while ensuring the penetration of the pressure inside and outside the nut base  10 . 
     The present disclosure can further disclose a method for mounting the limiting element when applied in the nut assembly. The method can include the following steps: 
     S 1 , sleeving the limiting element  40  on the nut base  10  and making the second limiting protrusion  42  inserting into the first limiting groove  15  though the notch of the first limiting groove  15 ; and 
     S 2 , rotating the limiting element  40  to make the second limiting protrusion  42  sliding into the corresponding second limiting groove  16 . 
     Moreover, it should be noted that the use of terms such as “first” and “second” to define parts is only for the convenience of distinguishing corresponding parts. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood as limiting the scope of protection of the present disclosure. 
     The technical features of the above-described embodiments may be combined in any combination. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, all should be considered as within the scope of this disclosure. 
     The above-described embodiments are merely illustrative of several embodiments of the present disclosure, and the description thereof is relatively specific and detailed, but is not to be construed as limiting the scope of the disclosure. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the disclosure. Therefore, the scope of the disclosure should be determined by the appended claims.