CN110608337B

CN110608337B - Quick-operation joint subassembly and female joint thereof

Info

Publication number: CN110608337B
Application number: CN201811582440.7A
Authority: CN
Inventors: 谢地; 牛锐; 马腾飞; 易怀军; 聂静良
Original assignee: China Aviation Optical Electrical Technology Co Ltd
Current assignee: China Aviation Optical Electrical Technology Co Ltd
Priority date: 2018-09-30
Filing date: 2018-12-24
Publication date: 2021-05-18
Anticipated expiration: 2038-12-24
Also published as: CN110608337A

Abstract

The invention relates to a quick connector assembly and a female connector thereof, wherein the front end of the female connector is an insertion end for being inserted and matched with a male connector, the female connector comprises a female connector shell, a female connector spool movably assembled in the female connector shell along the front-back direction, and a movable sealing sleeve positioned outside the front end of the female connector spool, the front end of the female connector spool and/or the movable sealing sleeve is provided with a pressure relief structure, an anti-drop limiting part is fixedly arranged on the female connector shell behind the female connector spool, a pre-pressing spring is arranged between the movable sealing sleeve and the rear end of the female connector spool in a pressing mode, the anti-drop limiting part is provided with a through hole extending from front to back, the front end of the female connector penetrates through the through hole and then is fixedly connected with the female connector spool, and a pressing elastic part is elastically pressed and arranged between the rear end of the pressing part and the female connector shell and/or.

Description

Quick-operation joint subassembly and female joint thereof

Technical Field

The invention relates to a quick connector assembly and a female connector thereof.

Background

In the liquid cooling system, the application of quick-operation joint is very extensive, and quick-operation joint is one kind and need not just can realize the joint that the pipeline communicates or breaks off with the help of the instrument, brings very big facility for the installation and the maintenance of liquid cooling system. Quick-operation joint subassembly generally includes male joint and female joint, the structure of female joint is generally as shown in fig. 1, the female joint includes both ends open-ended female first casing 1, fluid passage 2 has in the female first casing 1, install female first case 3 in the fluid passage 2, the left end external diameter of female first case 3 is great and form the edge of turning up, turn up along being assembled in female first casing 1 by

spacing jump ring

7 and 8 axial fixings of spacing step, be provided with movable sealing sleeve 4 between female first casing 1 and the right-hand member of female first case 3 (promptly with male joint cartridge complex spigot joint end) and female first casing 1. An inner sealing ring 6 is embedded outside the female valve core 3 to be in sealing fit with the inner side of the movable sealing sleeve 4, and an outer sealing ring 5 is embedded inside the female housing 1 to be in sealing fit with the outer side of the movable sealing sleeve 4. The outward turned edge is provided with a through hole, and a prepressing spring 9 is prepressed and assembled between the outward turned edge and the movable sealing sleeve 4. When the liquid cooling system is used specifically, the right end of the female connector is used for being plugged with the male connector, and the left end of the female connector is connected to a liquid cooling module of the liquid cooling system.

However, since the female valve body 3 is always axially fixed to the female housing 1, there are the following problems in actual use: firstly, when a liquid cooling system is operated or debugged, the liquid cooling module in the liquid cooling system is frequently required to be maintained, the pressure in the liquid cooling module can not be completely removed after the liquid cooling module is shut down, and when the liquid cooling module is transported and stored, when the ambient temperature rises, liquid in the liquid cooling module is heated and expands, the pressure is increased rapidly, and the pressure is enough to break the liquid cooling module; and secondly, the liquid cooling system runs under the rated pressure, the liquid cooling system may have the condition of unstable pressure supply, and when the sudden change of pressure is greater than the safe pressure of the liquid cooling module, the module can be damaged and bulge.

The problems are caused because the female valve core 3 cannot move left and right, and the pressure cannot be released when the pressure in the liquid cooling module is too high.

For this reason, the skilled person has developed two different types of female joints to solve the above-mentioned problems, one of which is shown in fig. 2 and 3, and the working principle, working process and most of the structures of the improved female joint are the same as those before the improvement, except that the turned-out edge of the female valve element 11 in the improved female joint has a certain interval from the limit step 10. The right end of the movable sealing sleeve 13 is provided with a flaring section 14, the female valve core 11 is provided with a discharge hole 16, and the discharge hole 16 is communicated with an annular groove for embedding an inner sealing ring 15. When pressure is required to be relieved, the female valve core 11 is pushed by high-pressure liquid in the liquid cooling module to move rightwards, the pre-pressing spring 12 is compressed, the inner sealing ring 15 is pushed to the flaring section 14, the inner sealing ring 15 is propped open by the high-pressure liquid, the outer side of the inner sealing ring is still attached to the movable sealing sleeve 13, a gap is formed between the inner side of the inner sealing ring and the female valve core 11, and the gap is connected with the drainage hole 16 to relieve pressure.

Another improved female joint is shown in chinese patent application with application publication No. CN104565638A, which discloses a quick joint assembly, wherein a female valve element can move in a guiding manner in a female housing, an inward-contracting section is provided at an insertion end of the female valve element, an inner seal ring seals a gap between the female valve element and a movable seal sleeve during normal use, and during pressure relief, the female valve element moves and moves relative to the inner seal ring, so that the inner seal ring corresponds to the inward-contracting section to relieve pressure.

In the two female connectors, the flaring section 14 or the retraction section form a pressure relief structure, so that pressure can be relieved when the pressure of the liquid cooling module is too high. However, in any of the above forms, the following problems are present: the pressure relief pressure of the female joint completely depends on the spring force of the pre-pressing spring, and the insertion force when the male joint and the female joint are inserted also completely depends on the spring force of the pre-pressing spring. When the drift diameter of the product is larger (the pressure relief stress area on the female joint is enlarged) or the required pressure relief pressure is larger, the spring force of the required pre-pressing spring needs to be increased, and higher requirements are provided for the material selection, the size or the processing technology of the spring. There are two drawbacks at this time: first, the spring may not be able to be manufactured by the forming technique of the spring; and secondly, even if the spring can be produced, the spring force of the pre-pressing spring also determines the inserting force of the male joint and the female joint, and after the spring force of the pre-pressing spring is increased, the inserting force required when the male joint and the female joint are inserted is increased, so that the inserting difficulty is increased, and the inserting hand feeling and the use of the product are influenced.

Disclosure of Invention

The invention aims to provide a female joint, which aims to solve the technical problem that in the prior art, the pressure relief pressure of the female joint and the insertion force of a male joint and a female joint are completely dependent on a pre-pressing spring, so that the male joint and the female joint are not easy to be inserted when the required pressure relief pressure is large; also provides a quick joint component using the female joint, so as to reduce the inserting difficulty of the male joint and the female joint.

In order to achieve the purpose, the technical scheme of the female joint is as follows: the utility model provides a female joint, female joint's front end is for being used for with male joint cartridge complex end of inserting, and female joint includes female first casing, along the fore-and-aft direction removal assembly in female first casing female first case and be located the outside movable sealing cover of female first case front end, and female first case and/or movable sealing cover's front end are equipped with pressure release structure, have set firmly the anticreep locating part in female first case's rear on female first casing, the pressure equipment has the pre-compaction spring between the rear end of movable sealing cover and female first case, the anticreep locating part has the perforation of fore-and-aft extension, female joint still include the front end run through this perforation after with female first case fixed continuous pressurization spare, along fore-and-aft direction elastic pressure equipment has the pressurization elastic component between the rear end of pressurization spare and female first casing and/or the anticreep locating part.

The invention has the beneficial effects that: female joint carries out the pressure release when liquid cooling module pressure risees, and female first case moves forward, needs compression pre-compaction spring during the removal, because female first case and pressurization piece fixed link to each other and pressurization piece and female first casing and/or anticreep locating part between be provided with the pressurization elastic component, female first case still need compress the pressurization elastic component when the removal, and from this, the pressure release pressure of female joint has been increased, is applicable to the great service environment of the great or required pressure release pressure of latus rectum. When the male joint and the female joint are inserted, the pressure piece is under the action of the elastic restoring force of the pressure elastic piece, and the female valve core is at the rear limit position under the action of the elastic restoring force of the pre-pressure spring. Because the rear end of the female valve core is blocked by the anti-drop limiting part, the magnitude of the insertion force is only determined by the pre-pressing spring when the male joint and the female joint are inserted, and therefore the insertion force required when the male joint and the female joint are inserted is reduced. According to the invention, by additionally arranging the pressurizing piece and the pressurizing elastic piece, the situation that both the pressure relief pressure and the insertion force are completely determined by the pre-pressing spring can be avoided, the pressure relief pressure is increased on the premise of not increasing the insertion force (or the insertion force is reduced on the premise of not reducing the pressure relief pressure), and the differential design of insertion and pressure relief is realized.

Furthermore, the anti-drop limiting part comprises a sleeve body provided with the through hole, and further comprises a connecting ring for connecting the sleeve body and the female head shell, wherein an inward turning edge is arranged at the front end of the through hole on the sleeve body, the pressurizing part is a pressurizing rod, the front end of the pressurizing rod penetrates through the inward turning edge and is fixedly connected with the female head valve core, a forward stopping step is arranged at the rear end of the pressurizing rod, and the pressurizing elastic part is arranged between the pressurizing rod and the sleeve body and is elastically pressed and mounted between the inward turning edge and the stopping step.

The effect of this scheme lies in, through setting up the cover body, enstrophe along and the stop step, can assemble the elastic component that pressurizes between pressure bar and the cover body, to the elastic compression and the elasticity release process of the elastic component that pressurizes carry out the direction of certain degree.

Furthermore, the front end of the sleeve body is embedded in the rear end of the female valve core.

The effect of this scheme lies in, inlays the front end of the cover body and inlays the dress inside the rear end of female first case, can reduce the length sum of the fore-and-aft direction of the cover body and female first case, has realized miniaturized design.

Furthermore, the rear end of the sleeve body is provided with a limiting rear end face which is matched with the stop step in a stop manner when the female valve core is decompressed and moves to the tail end, so that the female valve core is prevented from being separated from the female shell forward.

The effect of this scheme lies in, sets up behind the spacing rear end face, can restrict the limit that the forward pressure release of female first case removed.

Furthermore, the rear end of the female valve core is provided with a guide outward-turning edge, the guide outward-turning edge and the connecting ring are correspondingly provided with liquid through holes communicated with the inside and the outside of the female housing, the front end of the connecting ring is integrally formed with or is fixedly provided with pin shafts extending into the guide outward-turning edge in a split mode, and the pin shafts are circumferentially arranged at intervals at least two so that the guide outward-turning edge and the anti-falling limiting part are assembled together in a rotation stopping mode.

The effect of this scheme lies in, for guaranteeing the normal use of female joint, turns up in the direction all to set up the liquid through hole on edge and the go-between, has set up behind two at least circumference interval arrangement's the round pin axle, can guarantee that the direction turns up all the time and keep in the state that corresponds the link up along turning up the liquid through hole on edge and the go-between, satisfies the requirement of normal use.

The technical scheme of the quick connector assembly is as follows: the utility model provides a quick-operation joint subassembly, includes cartridge complex male joint and female joint, the front end of female joint for be used for with male joint cartridge complex insert the end of closing, the female joint includes female first casing, along the fore-and-aft direction removal assemble in female first case in female first casing female first case and be located the outside movable sealing cover of female first case front end, the front end of female first case and/or movable sealing cover is equipped with pressure release structure, female first casing is last to have set firmly the anticreep locating part in the rear of female first case, the pressure equipment has the pre-compaction spring between the rear end of movable sealing cover and female first case, the perforation that the anticreep locating part has the front and back extension, the female joint still include the front end run through behind this perforation with female first case fixed continuous pressurization spare, along the fore-and-aft direction elasticity pressure equipment has the pressurization elastic component between the rear end of pressurization spare and female first casing and/or.

Drawings

FIG. 1 is a schematic view of a prior art non-depressible female connector;

FIG. 2 is a prior art initial state diagram of a female connection that is depressible;

FIG. 3 is a schematic view of the female connector of FIG. 2 after venting;

FIG. 4 is a schematic view of an embodiment of the quick connector assembly of the present invention;

FIG. 5 is a schematic view of the female connector of FIG. 4 in an unpressurized state;

FIG. 6 is a right side view of FIG. 5;

FIG. 7 is a schematic view of the female connector of FIG. 4 with pressure relief;

description of reference numerals: 1-female housing; 2-a fluid channel; 3-female valve core; 4-movable sealing sleeve; 5-outer sealing ring; 6-inner sealing ring; 7-limiting clamp spring; 8-a limit step; 9-prepressing a spring; 10-a limit step; 11-female valve core; 12-a pre-compression spring; 13-a movable sealing sleeve; 14-a flared section; 15-inner sealing ring; 16-a drain hole; 200-a male connector; 21-male housing; 22-male valve core; 23-a male pre-compression spring; 300-a female connector; 31-a female housing first portion; 32-a female housing second portion; 33-a staple ring; 34-a staple; 35-an outer sealing ring; 36-movable sealing sleeve; 37-female valve core; 38-a drain hole; 39-inner sealing ring; 310-a pre-compression spring; 311-housing seal ring; 312-a compression spring; 313-a compression bar; 314-a stop collar; 315-limit clamp spring; 316-pin; 317-liquid through holes; 318-limit step.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings.

In the embodiment of the quick connector assembly of the present invention shown in fig. 4 to 7, the quick connector assembly comprises a male connector 200 and a female connector 300, and the male connector and the female connector are inserted and combined as shown in fig. 4. The male connector 200 includes a male housing 21, a male valve core 22 and a male preloading spring 23 arranged in the male housing 21 and press-fitted between the male valve core 22 and the male housing 21, the structure of the male connector is consistent with that of the prior art, and details will not be repeated in this embodiment.

The structure of the female joint 300 is as shown in fig. 5 to 7, the female joint 300 includes a female housing, wherein the female housing includes a first female housing portion 31 and a second female housing portion 32 that are fixedly assembled together, and specifically, the female housing portion can be fixedly assembled by a threaded connection, and in order to ensure the sealing performance during the fixing of the two portions and avoid the liquid leakage, a housing sealing ring 311 is disposed between the first female housing portion 31 and the second female housing portion 32. A clip ring 33 is attached to the female housing first portion 31, and a clip 34 is fixedly attached to the clip ring 33. The structure of this part can be referred to the chinese utility model patent with the publication number CN 203571282U.

The end of the female connector 300 that is inserted into the male connector 200 is defined as the front end, and the left end of the female connector 300 in fig. 5 is defined as the front end when inserted. The female head shell is a cylindrical shell with a fluid channel inside, a female head valve core 37 is arranged in the female head shell, a movable sealing sleeve 36 is arranged between the left end of the female head valve core 37 and the female head shell, an inner sealing ring 39 is embedded outside the female head valve core 37 and is in sealing fit with the inner side of the movable sealing sleeve 36, and an outer sealing ring 35 is embedded outside the movable sealing sleeve 36 and is in sealing fit with the inner side of the female head shell. A flared discharge section is arranged at the left end of the movable sealing sleeve 36, a discharge hole 38 is arranged at the left end of the female valve core 37, and the discharge hole 38 is communicated with the outer part of the female valve core 37 and a groove where the inner sealing ring 39 is located.

The outer diameter of the right end of the female valve core 37 is large to form an outward turning edge, the outward turning edge is in guide fit with the female housing, a pre-pressing spring 310 is pre-pressed between the outward turning edge and the movable sealing sleeve 36, as can be seen from fig. 5, the outer diameter of the right end of the movable sealing sleeve 36 is large, and the right end of the movable sealing sleeve 36 can be pressed on the female housing under the spring force of the pre-pressing spring 310.

In order to limit the right end of the female valve element 37 to prevent the female valve element 37 from coming off, a limiting sleeve 314 is fixedly assembled in the female housing in the axial direction, and the limiting sleeve 314 is positioned at the right side of the female valve element 37. Specifically, a limiting snap spring 315 is fixed to the right side of the limiting sleeve 314, a limiting step 318 facing to the right is further arranged on the inner wall surface of the female housing, and the limiting step 318 and the limiting snap spring 315 axially and fixedly assemble the limiting sleeve 314 in the female housing.

As can be seen from fig. 5, the stop collar 314 is an annular structure, and includes a sleeve body and a connecting ring, wherein the axial length of the sleeve body is greater than that of the connecting ring, and the left end of the sleeve body extends into the right end of the female valve element 37. A pressure lever 313 penetrates through the limiting sleeve 314, and the left end of the pressure lever 313 is screwed into the female valve core 37 to realize fixed connection with the female valve core 37. The left end of the pressure lever 313 is a small diameter section, and the right end is a large diameter section, so that the pressure lever 313 forms a stopping step towards the left, an inward turning edge is further arranged inside the limiting sleeve 314, and a pressurizing spring 312 is pressed between the inward turning edge and the stopping step of the pressure lever 313.

In order to ensure the liquid flow after the male connector 200 and the female connector 300 are inserted, as shown in fig. 6, a liquid through hole 317 is formed in the position limiting sleeve 314 and penetrates right and left, correspondingly, a liquid through hole 317 is also formed in the female valve element 37 (hidden in fig. 6 and not shown), and the liquid through holes 317 in the position limiting sleeve 314 and the female valve element 37 correspond right and left, so that the liquid in the liquid cooling module can flow out and in. In order to ensure that the two liquid through holes 317 correspond to each other left and right, as shown in fig. 5, a pin shaft 316 extending towards the left is integrally formed on the left side of the position limiting sleeve 314, and at least two pin shafts 316 are arranged at intervals along the circumferential direction, so that rotation stopping assembly between the position limiting sleeve 314 and the female valve element 37 can be ensured. Of course, in other embodiments, the pin shaft may also be separately fixed on the position-limiting sleeve.

As shown in fig. 5, which is a schematic view of the female connector 300 after the male connector 200 and the female connector 300 are separated, at this time, a left-right gap is formed between the pressing rod 313 and the position-limiting sleeve 314, and the pressing rod 313 and the female valve element 37 are both in the right limit position, so that the sealing performance of the liquid cooling module during normal use and transportation can be ensured. As shown in fig. 7, when the pressure in the liquid cooling module is suddenly increased, the high-pressure liquid pushes the pressure rod 313 and the female valve element 37 to move leftward, and in the process of moving leftward, the pre-pressing spring 310 and the pressurizing spring 312 are compressed, so that the inner sealing ring 39 sleeved outside the female valve element 37 is pushed to the flared section of the movable sealing sleeve 36, the inner sealing ring 39 is spread by the high-pressure liquid, the outer side of the inner sealing ring is still attached to the movable sealing sleeve 36, a gap is formed between the inner side of the inner sealing ring and the female valve element 37, and the gap is connected with the drainage hole 38 to perform pressure relief. The relief pressure is determined by the pre-compression spring 310 and the pressurizing spring 312.

When the male connector 200 and the female connector 300 are inserted, the rear end of the female valve element 37 is pressed against the limiting sleeve 314, so that the insertion force completely depends on the pre-pressing spring 310, and compared with the prior art, the insertion force is reduced.

In this embodiment, the left end of the female connector 300 is a plug end. The flared section of the movable sealing sleeve 13 forms a pressure relief structure, and in other embodiments, the pressure relief structure may be disposed on the female valve element as shown in the chinese patent application with application publication No. CN104565638A, or both the female valve element and the movable sealing sleeve may be disposed with pressure relief structures. The pressing rod 313 constitutes a pressing rod, i.e., a pressing member. The pressing spring 312 constitutes a pressing elastic member, and in other embodiments, the pressing elastic member may be a rubber pad or the like.

The stop collar 314 constitutes an anti-releasing limiting member, and in other embodiments, the stop collar may be removed, the limiting snap spring is used as an anti-releasing limiting member, the pressurizing member is fixed at the rear end of the female valve element, and the pressurizing elastic member is disposed between the pressurizing member and the female housing. Or in other embodiments, the pressing elastic members may be disposed between the anti-falling stopper and the pressing member and between the female housing and the pressing member.

In this embodiment, when the female valve element 37 is decompressed and moves to the end, the sleeve and the pressure rod 313 are in stop fit to prevent the female valve element 37 from coming off, and the right end face of the sleeve is the limiting rear end face.

In the specific embodiment of the female joint of the present invention, the structure of the female joint is the same as that in the above embodiments, and the details thereof are not repeated.

Claims

1. The utility model provides a female joint, female joint's front end for being used for with male joint cartridge complex insert the end that closes, female joint include female first casing, along the fore-and-aft direction remove the female first case of assembly in female first casing and be located the outside movable sealing cover of female first case front end, the front end of female first case and/or movable sealing cover is equipped with pressure release structure, has set firmly the anticreep locating part in the rear of female first case on female first casing, the pressure equipment has pre-compaction spring, its characterized in that between the rear end of movable sealing cover and female first case: the anti-disengaging limiting part is provided with a through hole extending from front to back, the female joint further comprises a pressurizing piece, the front end of the pressurizing piece penetrates through the through hole and then is fixedly connected with the female valve element, and a pressurizing elastic piece is elastically pressed between the rear end of the pressurizing piece and the female shell and/or the anti-disengaging limiting part along the front-back direction.

2. The box joint of claim 1, wherein: the anti-falling limiting part comprises a sleeve body provided with the through hole and a connecting ring for connecting the sleeve body and the female head shell, an inward turning edge is arranged at the front end of the through hole on the sleeve body, the pressurizing part is a pressurizing rod, the front end of the pressurizing rod penetrates through the inward turning edge and is fixedly connected with the female head valve core, a forward stopping step is arranged at the rear end of the pressurizing rod, and the pressurizing elastic part is arranged between the pressurizing rod and the sleeve body and is elastically pressed between the inward turning edge and the stopping step.

3. The box joint of claim 2, wherein: the front end of the sleeve body is embedded in the rear end of the female valve core.

4. The box joint of claim 2, wherein: the rear end of the sleeve body is provided with a limiting rear end face which is matched with the stopping step in a stopping way when the female valve core is decompressed and moves to the tail end, so that the female valve core is prevented from being separated from the female shell forwards.

5. The box joint according to claim 2 or 3 or 4, wherein: the rear end of the female head valve core is provided with a guide outward-turning edge, the guide outward-turning edge and the connecting ring are correspondingly provided with liquid through holes communicated with the inside and the outside of the female head shell, the front end of the connecting ring is integrally formed with or is fixedly provided with pin shafts extending into the guide outward-turning edge in a split mode, and the pin shafts are arranged at intervals in the circumferential direction, so that the guide outward-turning edge and the anti-falling limiting part are assembled together in a rotation stopping mode.

6. The utility model provides a quick-operation joint subassembly, includes cartridge complex male joint and female joint, the front end of female joint for being used for with the complex end of inserting of male joint cartridge, the female joint includes female first casing, along the fore-and-aft direction removal assemble in female first case in female first casing female first case and be located the outside movable sealing cover of female first case front end, the front end of female first case and/or movable sealing cover is equipped with the pressure release structure, has set firmly the anticreep locating part in the rear of female first case on the female first casing, the pressure equipment has pre-compaction spring, its characterized in that between the rear end of movable sealing cover and female first case: the anti-disengaging limiting part is provided with a through hole extending from front to back, the female joint further comprises a pressurizing piece, the front end of the pressurizing piece penetrates through the through hole and then is fixedly connected with the female valve element, and a pressurizing elastic piece is elastically pressed between the rear end of the pressurizing piece and the female shell and/or the anti-disengaging limiting part along the front-back direction.

7. The quick connector assembly of claim 6, wherein: the anti-falling limiting part comprises a sleeve body provided with the through hole and a connecting ring for connecting the sleeve body and the female head shell, an inward turning edge is arranged at the front end of the through hole on the sleeve body, the pressurizing part is a pressurizing rod, the front end of the pressurizing rod penetrates through the inward turning edge and is fixedly connected with the female head valve core, a forward stopping step is arranged at the rear end of the pressurizing rod, and the pressurizing elastic part is arranged between the pressurizing rod and the sleeve body and is elastically pressed between the inward turning edge and the stopping step.

8. The quick connector assembly of claim 7, wherein: the front end of the sleeve body is embedded in the rear end of the female valve core.

9. The quick connector assembly of claim 7, wherein: the rear end of the sleeve body is provided with a limiting rear end face which is matched with the stopping step in a stopping way when the female valve core is decompressed and moves to the tail end, so that the female valve core is prevented from being separated from the female shell forwards.

10. The quick connector assembly as claimed in claim 7 or 8 or 9, wherein: the rear end of the female head valve core is provided with a guide outward-turning edge, the guide outward-turning edge and the connecting ring are correspondingly provided with liquid through holes communicated with the inside and the outside of the female head shell, the front end of the connecting ring is integrally formed with or is fixedly provided with pin shafts extending into the guide outward-turning edge in a split mode, and the pin shafts are arranged at intervals in the circumferential direction, so that the guide outward-turning edge and the anti-falling limiting part are assembled together in a rotation stopping mode.