Patent Publication Number: US-9412529-B2

Title: Clasping connection structure of contactor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority to and the benefit of Chinese Patent Application No. 20140293863.2, filed on Jun. 27, 2014 and entitled “a clasping connection structure of a contactor”; the benefit of Chinese Patent Application No. 201410293855.8, filed on Jun. 27, 2014 and entitled “an accommodating chamber structure of a wiring terminal of a coil”; the benefit of Chinese Patent Application No. 201410293902.9, filed on Jun. 27, 2014 and entitled “a cover structure of a contactor”; the benefit of Chinese Patent Application No. 201410666492.8, filed on Nov. 20, 2014 and entitled “a rail mounting structure of an electric device”; the benefit of Chinese Patent Application No. 201420380050.2, filed on Jul. 10, 2014 and entitled “a rail mounting structure of an electric device”; and the benefit of Chinese Patent Application No. 201420346864.4, filed on Jun. 27, 2014 and entitled “a rail mounting structure of an electric device”, which are incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates generally to the technical field of the contactor assembling, and particularly to a clasping connection structure of a contactor. 
     BACKGROUND 
     In the conventional technology of contactor assembling, a bobbin is firstly disposed in a housing. At that moment, the bobbin is only disposed in a chamber of the housing instead of being fixed to the housing. The housing and the base are then assembled with screws. The contactor assembling structure has defects of: 
     Firstly, the bobbin is easy to fall off during automatic assembling since the bobbin and the housing are not fastened with each other, which is hard to achieve automatic assembling. 
     Secondly, the housing is fastened to the base via screws, and the screw connection needs to be performed by human, which is hard to achieve automatic assembling. 
     Thirdly, using screws to fasten the housing and the base increases the usage cost of screws, which leads to a relatively high cost. 
     In another aspect, in the conventional technology, for some electric device such as the contactor and the circuit breaker, the coil is usually winded on the bobbin, one end of the coil is electrically connected to a first conductive metal plate, a first screw is fastened to a first conductive metal plate to form a first wiring terminal, the other end of the coil is electrically connected to a second conductive metal plate, the second screw is fastened to the second conductive metal plate to form a second wiring terminal. 
     When an accommodating chamber structure of the wiring terminal of the coil is assembled, the first screw is firstly screwed in the first conductive metal plate, the second screw is screwed in the second conductive metal plate, then the combination of the first screw and the first conductive metal plate and the combination of the second screw and the second conductive metal plate are inserted into the bobbin integrally. Then the first screw and the second screw are loosen to wind the coil, otherwise, the coil may kink. During detection, the first screw and the second screw need to be unscrewed and a probe is used to contact the coil to perform detection. As a result, when the accommodating chamber structure of the wiring terminal of the coil in the conventional technology is assembled, the first screw and the second screw need to be screwed and unscrewed repeatedly, which cause the assembling process is complex, and the automatic assembling may not be achieved. 
     In addition, to prevent dust from entering the accommodating chamber structure of the wiring terminal of the coil and to improve the level of protection, a protective cover for protecting the coil wiring terminal is usually provided on the housing after the bobbin is disposed in the housing. However, the overall structure has many plastic components, which leads to a complex structure and increased cost. 
     In another aspect, in the conventional technology, to improve the level of protection of the contactor, a cover is usually disposed. The cover is assembled to the housing of the contactor. Meanwhile, to improve the assistant functions of the contactor, the cover of the contactor is usually disposed with contact terminal assistant module, delay assistant module and other function assistant modules. As a result, in the conventional technology the cover is usually made hollow at corresponding positions to assemble the function assistant modules. Due to this, when the contactor is not assembled in the function assistant modules, foreign matter is easy to enter the contactor and affect the normal operation of the contactor. An additional protective cover is needed, thusly the cost is increased. 
     In another aspect, a contact carrier of the contactor is assembled in the housing. When the contactor is not conducted, the contact carrier is exposed out of the cover, the cover in the conventional technology is usually not provided with a protective cover for protecting the exposed part of the contact carrier, and the user may mis-operate and press the contact carrier to conduct the contactor, which damages the contactor controlling equipment and affect the personal safety. 
     In still another aspect, the electric device such as the contactor, the circuit breaker, the switch and thermal relay in the conventional technology are usually mounted with the help of rails. As shown in  FIG. 35 , which shows a rail mounting structure, a contactor base  4010  is formed with a mounting slot  4020  whose width matches the width of the rail (not shown). Each of the two sides of the mounting slot  4020  is provided with clasps  4030 , and a clasping slot is formed between the clasp  4030  and the base  4010 . The clasp  4030  at one side is fixedly assembled at the base  4010 , and the clasp  4030  at the other side is movably assembled at the base  4010  via a spring  4040 . 
     When the rail is assembled to the mounting slot, the rail is clasped in the clasping slot between the clasps at two sides and the base, and is fixed by the elastic force of the spring. However, the disadvantages are: firstly, the rail mounting structure is complex, thusly the manufacturing cost is high and increased; secondly, the rail mounting structure has many components, which further increases the cost. 
     Another rail mounting structure is provided in the conventional technology. A mounting slot is formed on the contactor base, each of the two sides of the mounting slot is provided with the clasps, and a clasping slot is formed between the clasp and the base. One clasping slot at one side is provided with a torsional spring by which elastic force is provided and the rail is fixed. However, the disadvantages are: firstly, the torsional spring principle of the rail mounting structure leads to only a single point is supported and stressed, which makes the rail shake; secondly, the rail is fixed by the elastic force of the torsional spring, which makes it unable to assemble the rail from a side, and the assembling is inconvenient. 
     SUMMARY 
     To prevent the problems in the conventional technology, according to the first aspect, the invention provides a clasping connection structure of a contactor, which makes the contactor adapt to the automatic assembling and has reduced manufacturing cost. 
     To achieve the problem above, the first aspect of the invention provides the technical solution of: 
     A clasping connection structure of a contactor, including a base, a housing and a bobbin; accommodating chambers being formed on the housing and configured to accommodate mounting contacts, the accommodating chambers being separated via a side plate, wherein, the bobbin and the housing are connected via a first clasp, the first clasp is protruded and extended at a central side plate of the housing, the central side plate is located at an axial center line of the housing, correspondingly, a limiting slot for matching with the central side plate is formed on the bobbin, the bobbin is inserted in the housing, the central side plate passes through the limiting slot, a clasp of the central side plate is hooked on the bobbin at a side of the limiting slot, to connect the bobbin and the housing, the housing and the base are connected via a second clasp. 
     Furthermore, the clasp of the central side plate comprises a tapered-pushing surface and a clamping stopper surface adjacently disposed with each other, the clamping stopper surface abuts against the bobbin at a side of the limiting slot. 
     Furthermore, the second clasp is a hook formed on the base, a clasping slot for matching with the hook is formed on the housing, and the hook is engaged in the clasping slot to connect the base and the housing. 
     By the solution above, the bobbin and the housing of the invention are connected via the first clasp, the housing and the base are connected via the second clasp, during the assembling, the bobbin and the housing are clasped first, and then the housing and the base are clasped. As a result the invention has the following advantages compared with the conventional technology of: 
     Firstly, a clasp is protruded and extended on the central side plate of the housing, the central side plate is on the axial center line of the housing, that is the side plate structure of the accommodating chamber originally existed on the housing is used, the clasp is formed on the basis of the central side plate, and thusly the design is easy, ingenious, without complex structure, as a result, the complex core-pulling and avoiding problem existed on the mould may not generate, only to form a protruding clasp by injection molding on the current central side plate. Thusly, when the housing especially the clasp of the central side plate is injection-molded, the designed mould structure is simple, the mould cost is saved and the core-pulling is easy. 
     Secondly, the central side plate passes through the limiting slot, the clasp of the central side plate is hooked on a bobbin at one side of the limiting slot, thusly the bobbin and the housing are connected, and one point clasp (engagement) is realized. In addition only one clasp is needed to realize the assembling of the bobbin and the housing, which is easy to assemble and easy to disassembly. During disassembling, it only needs to deflect the bobbin slightly to separate. 
     According to a second technical solution, an accommodating chamber structure of a wiring terminal of a coil is provided, which is adapted to the automatic assembling, reduces manufacturing cost, has concise and reliable structure, and does not need a special protective cover for covering the wiring terminal of the coil. 
     To achieve the object as above, the invention provides the technical solution of: 
     An accommodating chamber structure of wiring terminal of coil, wherein, an accommodating chamber which is opened at a side portion is provided on the bobbin, a conductive metal plate is assembled in the accommodating chamber to electrically connect with the coil, a limiting structure formed in the accommodating chamber allows the screw to be assembled at the opening of the side portion of the accommodating chamber without falling off. A through hole with IP2X level of protection is formed on the top of the accommodating chamber, the diameter of the through hole is larger than the external diameter of the head of the screw. A slot is formed at the front side wall of the accommodating chamber, so that the conductive metal plate is exposed. 
     Furthermore, the limiting structure is an elastic sheet integrally formed on a side wall of the accommodating chamber, the opening between the elastic sheet and the side wall is smaller than the head of the screw, and the elastic sheet elastically clamps the head of the screw. 
     Furthermore, an end of the elastic sheet is integrally formed with the side wall of the accommodating chamber, the elastic sheet is tapered from the inner side of the accommodating chamber to the opening of the side portion of the accommodating chamber, the other end of the elastic sheet forms an elastic clamping opening with the accommodating chamber, the other end of the elastic sheet is formed with a guiding surface, the screw enters a clamping space enclosed by the elastic sheet and the side wall of the accommodating chamber from the elastic clamping opening with the help of the guiding surface. 
     Furthermore, the limiting structure may also be a protrusion integrally formed on the side wall of the accommodating chamber. The opening formed between the protrusion and the side wall is smaller than the head of the screw, and the protrusion elastically clamps at the head of the screw. 
     Furthermore, the protrusions may be two symmetrically-disposed protrusions, and the distance between the two protrusions is smaller than the head of the screw. 
     Furthermore, two ribs are formed at the bottom of the accommodating chamber, the distance between the two ribs is smaller than the external diameter of the screw, and the screw is embedded in the two ribs. 
     Furthermore, a protective cover is integrally formed on an upper of the accommodating chamber. 
     Furthermore, a plurality of accommodating chambers which are opened at a side portion are formed on the bobbin, a conductive metal plate is mounted in the each accommodating chamber to electrically connect the coil, a screw is accommodated in the accommodating chamber via the side portion opening, a limiting structure is formed in the accommodating chamber to prevent the screw from falling off. A through hole with IP2X level of protection is formed on the top of the accommodating chamber, the diameter of the through hole is larger than the external diameter of the head of the screw. A slot is formed at the front side wall of the accommodating chamber, the conductive metal plate is exposed; an air insulating area is formed between the accommodating chambers. 
     By the solution above, during the assembling of the invention, the conductive metal plate is winded with the coil and disposed in the bobbin, then a robot is used to dispose the screw in the accommodating chamber from the side portion opening of the accommodating chamber, at that moment, the limiting structure in the accommodating chamber limits the loosening of the screw; at last the screw is fastened on the conductive metal plate to finish assembling. 
     In the invention, the coil is firstly winded on the conductive metal plate and then assembled to the bobbin, at that moment the screw is not needed. A limiting structure is located in the accommodating chamber, which allows the screw to be assembled from the side opening of the accommodating chamber without falling off. On the contrary, in the conventional technology, it is needed to assemble the screw on the conductive metal plate first, and then assemble it to the bobbin, otherwise, the screw may fall off. After the conductive metal plate is assembled to the bobbin, the screw is unscrewed to wind the coil, otherwise, the screw may lead to wire-kinking. After the winding is finished, the screw needs to be fastened for detection, which needs to screw or unscrew the screw repeatedly. To the wiring terminal in the invention, during the assembling, it is not needed to screw or unscrew the screw repeatedly, as a result, the invention may be assembled automatically, and the assembling process is simple, the manufacturing cost is reduced. 
     Meanwhile, the end of the conductive metal plate is exposed to allow the probe to directly contact the conductive metal plate for detection, and the detection is more convenient. 
     The screw is embedded in two ribs to prevent screw from loosing, and the protective cover is integrally formed on the top of the accommodating chamber, which makes it unnecessary to dispose the other protective cover additionally, the structure is simple and compact and the level of protection may achieve IP20. 
     According to a third technical solution of the invention, a cover structure of a contactor is provided, so that foreign matter and mis-operating can both be efficiently prevented when the function assistant modules are not yet assembled to the contactor, furthermore, assembling the function assistant module is easy to perform, and the contactor of the invention is cost-saving. 
     To achieve the object above, the technical solution of the invention is: 
     A cover structure of the contactor, mounted on the contactor housing. Wherein, a hollow portion is formed on the cover, the hollow portion allows a part of the contact carrier of the contactor exposed from the cover to be accommodated therein, and first protective covers which may be pried are disposed at two opposite sides of the hollow portion. 
     Furthermore, the pried connection between the first protective cover and the cover is: the first protective cover is connected to the cover via ribs or tearing lines. 
     Furthermore, the two first protective covers are co-axial and disposed in the same plane. 
     Furthermore, two sides of the hollow portion are further disposed with second protective covers, which may also be pried, the second protective covers are protruded and disposed on the cover, the protruding part is used to accommodate a part of the contact carrier exposed from the cover. 
     Furthermore, the pried connection between the second protective cover and the cover is: the second protective cover is connected to the cover via ribs or tearing lines. 
     Furthermore, the two first protective covers and second protective covers are co-axial. 
     By the solution above, two first protective covers which may be pried are disposed at two opposite sides of the hollow portion, during assembling two sets of function assistant modules, it is not needed to pry the first protective covers, and when four sets of function assistant modules are assembled, two opposite first protective covers at two sides of the hollow portion are pried to assemble the function assistant modules, to make the function assistant module operated normally. 
     At the same time, two opposite second protective covers which may be pried are disposed at two sides of the hollow portion, the second protective cover is protruded on the cover, and the protruding part allows the part of the contact carrier exposed from the cover to accommodate therein. Thusly when the function assistant modules are not assembled, the part of the contact carrier exposed from the cover is accommodated in the protruding part of the second protective cover, which effectively avoids human pressing on the contact carrier to make the contactor conducted and damage the contactor controlling equipment and affect personal safety. When two sets of the function assistant modules are needed, the second protective covers are pried to form assembling portions to assemble, when four sets of function assistant modules are needed to assemble, two sets of first protective covers are pried in addition to the two second protective covers, the assembling is convenient and the cost is saved. 
     According to the fourth technical solution of the invention, a rail mounting structure of an electric device is provided to make it have the simple structure and reduced the manufacturing cost, and the rail is assembled stably, and is adapted to the automatic assembling. 
     To achieve the object above, the technical solution of the invention is: 
     A rail mounting structure of an electric device, wherein, an mounting slot is formed on the base of the electric device, at least one first fixing clasp is formed on one side of the mounting slot, a first clasping slot is formed between the first fixing clasp and the base; a second fixing clasp is formed at the other side of the mounting slot, a second clasping slot is formed between the second fixing clasp and the base; a first limiting block and a second limiting block are formed at two sides of the second fixing clasp, respectively, a first limiting slot is formed between the first limiting block and the base, and a second limiting slot is formed between the second limiting block and the base. The first limiting slot and the second limiting slot are arc-shaped limiting slots, two ends of a snap spring are arc-shaped and disposed in the first limiting slot and the second limiting slot, respectively, and form linear contact with the side walls of the first limiting slot and the second limiting slot, the middle stage of the snap spring is in the second clasping slot. 
     Furthermore, ribs are formed on the side walls of the first limiting slot and second limiting slot, and disposed above the snap spring. 
     Furthermore, the width of the second clasping slot becomes wider gradually from inner part to the inserting opening of the snap spring. 
     Furthermore, tapered guiding surfaces are formed respectively on the first limiting block and a second limiting block. 
     Furthermore, the second fixing clasp, the first limiting block and the second limiting block are disposed as a reverse-trapezoid shape, correspondingly, the snap spring is a reverse-trapezoid shape with a top opening, and the middle stage thereof is straight or curved stage. 
     Furthermore, the first limiting block and the second limiting block are formed by two parallel half-cylinders, and tapered surfaces are formed on each of the half-cylinders, respectively. 
     By the solution above, when the electric device is mounted via the rail, one side of the rail is disposed in the first clasping slot, the other side is disposed in the second clasping slot, the rail elastically contacts to the middle stage of the snap spring to deform the snap spring elastically, two ends of the snap spring abut against the base, the first limiting slot and the second limiting slot are arc-shaped limiting slots, two ends of the snap spring are arc-shaped and located in the first limiting slot and the second limiting slot, and have linear contact with the side walls of the first limiting slot and the second limiting slot, which has the advantages of: 
     Firstly, two ends of the snap spring linearly contact with the side walls of the first limiting slot and the second limiting slot, which make the snap structure mount stable and not easy to fall off. 
     Secondly, the leaf spring principle of the snap spring makes the rail mount stably. 
     Thirdly, the snap spring is used to allow the rail to be mounted from the side, which is easy to assemble. 
     Fourth, only a snap spring is needed to mount the device to the rail, the manufacturing and usage cost thereof can be reduced. 
     During assembling the snap spring, firstly the snap spring is disposed in the mounting slot, the middle stage of the snap spring is located opposite to the second fixing clasp, two ends of the snap spring correspond to the first limiting block and the second limiting block; the snap spring is moved to get close to the second fixing clasp, to make the middle stage of the snap spring in the second clasping slot, two ends of the snap spring slide into the first limiting slot and the second limiting slot via the tapered guiding surface, the assembling process have no structure block, thusly it can achieve the automatic assembling and save manufacturing cost. 
     The ribs are formed on the side walls of the first limiting slot and the second limiting slot, the ribs are disposed on the snap spring to prevent two ends of the snap spring from warping under pressure, thusly prevent the falling off of the snap spring. At the same time, the width of the second clasping slot becomes wider gradually from inner part to the inserting opening of the snap spring, which effectively avoids falling off of the snap spring due to warping of the middle stage of the snap spring under pressure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are used to provide a further understanding of the invention, which are incorporated in and constitute a part of this application, illustrate embodiments of the present invention together with the description serve to explain the principles of the invention. 
       In the Figures, 
         FIG. 1  is a sectional view of the invention; 
         FIG. 2  is a sectional view of the invention in another point of view; 
         FIG. 3 a    is schematic view showing the structure of the base of the invention. 
         FIG. 3 b    is schematic view showing the structure of the bobbin of the invention. 
         FIG. 3 c    is schematic view showing the structure of the housing of the invention. 
         FIG. 4  is a partial sectional view of the invention. 
         FIG. 5  is a partial enlarged view of  FIG. 4 ; 
         FIG. 6  is a top view of the invention; 
         FIG. 7  is a D-D sectional view of  FIG. 6 ; 
         FIG. 8  is a partial enlarged view of  FIG. 7 ; 
         FIG. 9 a    is a schematic view showing the structure of the invention before screw is assembled; 
         FIG. 9 b    is a schematic view showing the structure of the invention after screw is assembled; 
         FIG. 10  is a sectional view of the invention; 
         FIG. 11 a    is a partial enlarged view of  FIG. 10 ; 
         FIG. 11 b    is an A-A directional view of  FIG. 10 ; 
         FIG. 12  is another sectional view of the invention; 
         FIG. 13  is a partial enlarged view of  FIG. 12 ; 
         FIG. 14 a    is a first schematic view showing assembling the screw; 
         FIG. 14 b    is a second schematic view showing assembling the screw; 
         FIG. 14 c    is a third schematic view showing assembling the screw; 
         FIG. 15  is a schematic view showing another structure of the limiting structure in the invention; 
         FIG. 16  is a partial enlarged view of  FIG. 15 ; 
         FIG. 17  is a B-B sectional view of  FIG. 15 ; 
         FIG. 18  is a schematic view showing the structure of the invention before second protective cover is assembled; 
         FIG. 19  is a top view of the invention without the second protective cover; 
         FIG. 20  is a schematic view showing the structure of the invention after the second protective cover is assembled; 
         FIG. 21  is a top view of the invention with the second protective cover assembled; 
         FIG. 22  is a schematic view of the invention when the second protective cover is disposed from another point of view; 
         FIG. 23  is a schematic view showing the invention assembled to the contactor when the second protective cover is assembled; 
         FIG. 24  is a schematic view showing the state that the second protective covers are pried when two sets of function assistant modules are assembled; 
         FIG. 25  is a schematic view showing the process of assembling the two sets of function assistant modules; 
         FIG. 26  is a schematic view showing that the two sets of function assistant modules are finished assembling; 
         FIG. 27  is a schematic view showing the state that the second protective covers and the first protective covers are pried when four sets of function assistant modules are assembled; 
         FIG. 28  is a schematic view showing the process of assembling the four sets of function assistant modules; 
         FIG. 29  is a schematic view showing that the four sets of function assistant modules are finished assembling; 
         FIG. 30  is a schematic view showing the structure of the invention; 
         FIG. 31  is a top view of the invention; 
         FIG. 32 a    is a first schematic view showing the assembling process of the invention; 
         FIG. 32 b    is a second schematic view showing the assembling process of the invention; 
         FIG. 32 c    is a third schematic view showing the assembling process of the invention; 
         FIG. 33  is a schematic view of assembling the rail of the invention; 
         FIG. 34  is a sectional view of the invention; and 
         FIG. 35  is a schematic view of the rail mounting structure in the conventional technology. 
     
    
    
     REFERENCE NUMERALS 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 base 101 
                 hook 1011 
               
               
                 bobbin 102 
                 limiting slot 1021 
               
               
                 housing 103 
                 accommodating chamber 1030 
               
               
                 side plate 1031 
               
               
                 clasp 10311 
                 tapered-pushing surface 103111 
               
               
                 clamping stopper surface 103112 
                 clasping slot 1032 
               
               
                 first clasp 104 
                 second clasp 105 
               
               
                 bobbin 2010 
                 first accommodating chamber 201 
               
               
                 opening 2011 
                 limiting structure 2012 
               
               
                 elastic sheet 20121 
                 protrusion 20122 
               
               
                 through hole 2013 
                 slot 2014 
               
               
                 rib 2015 
                 second accommodating chamber 202 
               
               
                 through hole 2021 
                 slot 2022 
               
               
                 first conductive metal plate 203 
                 second conductive metal plate 204 
               
               
                 first screw 205 
                 second screw 206 
               
               
                 protective cover 207 
                 air insulating area 208 
               
               
                 housing 3010 
                 function assistant module 3020 
               
               
                 cover 301 
                 hollow portion 3011 
               
               
                 first protective cover 3012 
                 second protective cover 3013 
               
               
                 base 4010 
                 mounting slot 4020 
               
               
                 clasp 4030 
                 spring 4040 
               
               
                 electric device 40100 
               
               
                 base 401 
                 mounting slot 4011 
               
               
                 first fixing clasp 4012 
                 first clasping slot 4013 
               
               
                 second fixing clasp 4014 
                 second clasping slot 4015 
               
               
                 first limiting block 4016 
                 second limiting block 4017 
               
               
                 tapered guiding surface 
                 first limiting slot 4018 
               
               
                 (40161, 40171) 
               
               
                 second limiting slot 4019 
                 snap spring 402 
               
               
                 rail 403 
               
               
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION 
     Hereinafter, the embodiments of the present disclosure will be described in detail in conjunction with the drawings. 
     Technical Solution 1 
     As shown from  FIG. 1  to  FIG. 8 , the invention discloses a clasping connection structure of a contactor, including a base  101 , a bobbin  102  and a housing  103 . A plurality of accommodating chambers  1030  are formed on the housing for assembling contact head. The accommodating chambers  1030  are separated by a side plate  1031 , as shown in  FIG. 3   c.    
     As shown in  FIG. 7  and  FIG. 8 , the bobbin  102  is connected to the housing  103  via a first clasp  104 , as shown in  FIG. 4  and  FIG. 5  accompanying with  FIG. 3 b    and  FIG. 3 c   , the first clasp  104  is connected to form an clasp  10311  which is protruded and extended from the central side plate  1031  of the housing  103 . The central side plate  1031  is located on an axial center line of the housing  103 , and the clasp  10311  is formed at the end of the central side plate  1031 . Correspondingly, as shown in  FIG. 3 b   , the bobbin  102  is provided with a limiting slot  1021  matching with the first central side plate  1031 , the bobbin  102  is inserted into the housing  103 , the central side plate  1031  passes through the limiting slot  1021 , the clasp  10311  of the central side plate  1031  is hooked on a bobbin  102  at one side of the limiting slot  1021 , as shown in  FIG. 7  and  FIG. 8 , to connect the bobbin  102  and the housing  103 , 
     The housing  103  and the base  101  are connected via a second clasp  105 . The second clasp  105  includes a hook  1011  formed on the base  101 , as shown in  FIG. 3 a   , there are four hooks  1011  in the embodiment, and four clasping slots  1032  are formed on the housing  103  to match the hooks  1011 , as shown in  FIG. 4  and  FIG. 5 , the hooks  1011  are engaged in the clasping slots  1032  to connect the base  101  and the housing  103 , as shown in  FIG. 1  and  FIG. 2 . 
     A clasp  10311  is protruded and extended from the central side plate  1031  of the housing  103 . That is, the structure of the side plate  1031  of the accommodating chamber  1030  originally existed on the housing  103  is used to form the clasp  10311  on the basis of the central side plate  1031 , the design is easy, ingenious, without complex structure, as a result, the complex core-pulling and avoiding problem existed on conventional mould may not generate, but only to form a protruding clasp  10311  by injection molding on the current central side plate  1031 . Thusly, when the housing  103  especially the clasp  10311  of the central side plate  1031  is injection-molded, the designed mould structure is simple, the mould cost is saved and the core-pulling is easy. 
     Besides, the central side plate  1031  passes through the limiting slot  1021 , the clasp  10311  of the central side plate  1031  is hooked on a bobbin  102  at one side of the limiting slot  1021 , thusly the bobbin  102  and the housing  103  are connected, and thusly one point engagement (clasp  10311 ) is realized. Only the clasp  10311  is needed to realize the assembling of the bobbin  102  and the housing  103 , to make the bobbin  102  and the housing  103  easy to assemble and easy to detach. During detaching, it only needs to deflect the bobbin  102  slightly to disengage. 
     The clasp  10311  includes a tapered-pushing surface  103111  and a clamping stopper surface  103112  adjacent with each other, the clamping stopper surface  103112  abuts against the outer side wall of the first limiting slot  1021 . 
     During assembling, the bobbin  102  and the housing  103  are engaged first, and then the housing  103  and the base  101  are engaged without the need of screw fastening, which is adapted to the automatic assembling, reduces assembling cost, and reduces the screw cost and human cost. 
     The Second Technical Solution 
     Hereinafter the invention is illustrated accompanying with  FIG. 9 a    to  FIG. 17 . 
     As shown from  FIG. 9 a    to  FIG. 13 , in the invention the contactor is taken as an example to disclose an accommodating chamber structure of wiring terminal of the coil, a first accommodating chamber  201  and a second accommodating chamber  202  are formed on the bobbin  2010 . 
     The first conductive metal plate  203  is assembled in the first accommodating chamber  201  and is electrically connected to an end of the coil, a side portion of the first accommodating chamber  201  is provided with an opening  2011 , the first screw  205  is disposed in the first accommodating chamber  201  via the opening  2011 , the side wall of the first accommodating chamber  201  is formed with a limiting structure  2012  for limiting the looseness of the first screw  205 . As shown in  FIG. 11 b   , the top of the first accommodating chamber  201  is provided with a through hole  2013  corresponding to the head of the first screw  205 . A slot  2014  is formed at a side portion of the first accommodating chamber  201  corresponding to an end of the first conductive metal plate  203 . The end of the first conductive metal plate  203  is exposed, and thusly a probe may directly contact the first conductive metal plate  203  during the detection, which makes detection more convenient. 
     In the embodiment, as shown in  FIG. 11 a    and  FIG. 11 b   , the limiting structure  2012  is preferable an elastic sheet  20121  integrally formed on a side wall of the first accommodating chamber  201 , the opening between the elastic sheet  20121  and the side wall is smaller than the head of the first screw  205 , the elastic sheet  20121  elastically clamps the head of the first screw  205 , the elastic sheet  20121  is plastic sheet with elastic. 
     An end of the elastic sheet  20121  is integrally formed with the side wall of the first accommodating chamber  201 , the elastic sheet  20121  is tapered from the inner side of the first accommodating chamber  201  to the opening  2011  of the side portion of the first accommodating chamber  201 , the other end of the elastic sheet  20121  forms an elastic clamping opening together with the first accommodating chamber  201 , the other end of the elastic sheet  20121  is formed with a guiding surface, the first screw  205  enters the clamping space enclosed by the elastic sheet  20121  and the side wall of the first accommodating chamber  201  from the elastic clamping opening with the help of the guiding surface. The elastic sheet  20121  facilitates the first screw  205  to enter the clamping space enclosed by the elastic sheet  20121  and the side wall of the first accommodating chamber  201 , and at the same time facilitates the taking out of the first screw  205 , as shown in  FIG. 11 a    to  FIG. 11   c.    
     As shown from  FIG. 15  to  FIG. 17 , the limiting structure  2012  may also be a protrusion  20122  integrally formed on the side wall of the first accommodating chamber  201 . The opening formed between the protrusion  20122  and the side wall is smaller than the head of the first screw  205 , and the protrusion  20122  elastically clamps at the head of the first screw  205 . 
     The protrusions  20122  may be two symmetrically-disposed protrusions, the distance between the two protrusions  20122  is smaller than the head of the first screw  205 . 
     As shown in  FIG. 12  and  FIG. 13 , in the embodiment, two ribs  2015  are formed at the bottom of the first accommodating chamber  201 , the distance between the two ribs  2015  is smaller than the external diameter of the first screw  205 , the first screw  205  is embedded in the two ribs  2015  to avoid looseness of the first screw  205 . 
     The second accommodating chamber  202  has the same structure as that of the first accommodating chamber  201 , the second conductive metal plate  204  is assembled at the second accommodating chamber  202 , and electrically connected to the other end of the coil, a side portion of the second accommodating chamber  202  has an opening (not shown), the second screw  206  is disposed in the second accommodating chamber  202  via the opening, the side wall of the second accommodating chamber  202  is provided with limiting structure  2012  for limiting the looseness of the second screw  206 , the top of the second accommodating chamber  202  is formed with a through hole  2021  corresponding to the head of the second screw  206 . A slot  2022  is formed at the side portion of the second accommodating chamber  202  corresponding to an end of the second conductive metal plate  204 , the end of the second conductive metal plate  204  is exposed, and thusly a probe may directly contact the second conductive metal plate  204  during the detection, which makes the detection more convenient. 
     In the embodiment, as shown in  FIG. 11 a    and  FIG. 11 b   , the limiting structure  2012  is preferably an elastic sheet  20121  integrally formed on a side wall of the second accommodating chamber  202 , the opening between the elastic sheet  20121  and the side wall is smaller than the head of the second screw  206 , the elastic sheet  20121  elastically clamps the head of the second screw  206 , the elastic sheet  20121  is plastic sheet with elastic. The elastic sheet  20121  in the second accommodating chamber  202  and the elastic sheet  20121  in the first accommodating chamber  201  are disposed in the same manner, which is not illustrated for concise purpose. 
     As shown in  FIG. 15  and  FIG. 17 , the limiting structure  2012  may also be a protrusion  20122  which is elastic and integrally formed at the side wall of the second accommodating chamber  202 . The opening formed between the protrusion  20122  and the side wall is smaller than the head of the second screw  206 , and the protrusion  20122  elastically clamps at the head of the second screw  206 . 
     The protrusions  20122  may be two symmetrically-disposed protrusions, the distance between the two protrusions  20122  is smaller than the head of the second screw  206 . 
     Similarly, two ribs  2015  are formed at the bottom of the second accommodating chamber  202 , the distance between the two ribs  2015  is smaller than the external diameter of the second screw  206 , and the second screw  206  is embedded in the two ribs  2015  to avoid looseness of the second screw  206 . 
     A protective cover  207  is integrally formed on the top of the first accommodating chamber  201  and the second accommodating chamber  202 , and thusly the protective cover does not need to be disposed additionally, the structure is easy and compact, and the level of protection may achieve IP20. 
     An air insulating area  208  is disposed between the first accommodating chamber  201  and the second accommodating chamber  202 , thusly the electric clearance and the creep distance between the first screw  205  and the second screw  206  are enough, and thusly a large enough recess is located between the first accommodating chamber  201  and the second accommodating chamber  202 , and the large enough electric clearance and creep distance are ensured. 
     The contactor is taken as an example in the above to illustrate the wiring terminal structure, and the wiring terminal structure may be used in other electric device such as the circuit breaker or the switch. 
     The Third Technical Solution: 
     Hereinafter the detail embodiment is illustrated accompanying with  FIG. 18  to  FIG. 29 . 
     As shown in  FIG. 18  to  FIG. 29 , the invention discloses a cover structure of the contactor mounted on the contactor housing  3010 . As shown in  FIG. 23 , a hollow portion  3011  is formed on the cover  3011 , the hollow portion  3011  allows a part of the contact carrier of the contactor exposed from the cover  301  to accommodate therein, at the same time, the hollow portion  3011  may also allow two sets of function assistant modules  3020  to be assembled in, the function assistant module  3020  may be a contact terminal assistant module, a delay assistant module and so on, as shown in  FIG. 26 , two opposite first protective covers  3012  which may be pried are disposed at two sides of the hollow portion  3011 , as shown in  FIG. 18  and  FIG. 19 . 
     The pried connection between the first protective cover  3012  and the cover  301  may be: the first protective cover  3012  is connected to the cover  301  via ribs or tearing lines, in the embodiment, the first protective cover  3012  is connected to the cover  301  via the ribs  30121 , as shown in  FIG. 19 , the two first protective covers  3012  are co-axial and disposed in the same plane. 
     As shown in  FIG. 20  to  FIG. 22 , two sides of the hollow portion  3011  are further disposed with second protective covers  3013  which may also be pried. The second protective covers  3013  are protruded and disposed on the cover  301 . The protruding part is used to accommodate a part of the contact carrier exposed from the cover  301 . 
     The pried structure between the second protective cover  3013  and the cover  301  may be: the second protective cover  3013  is connected to the cover  301  via ribs or tearing lines, in the embodiment, the two first protective covers  3012  and the two second protective covers  3013  are co-axially disposed, as shown in  FIG. 21 . 
     Two opposite first protective covers  3012  which may be pried are disposed at two sides of the hollow portion  3011 , when two sets of function assistant modules  3020  needs to be assembled, it is not needed to pry the first protective covers  3012 , and as shown in  FIG. 24  to  FIG. 26 , when four sets of function assistant modules  3020  needs to be assembled, two first protective covers  3012  at two sides of the hollow portion  3011  are pried to assemble the function assistant modules  3020 , to allow the function assistant module  3020  to operate normally. As shown in  FIG. 27  to  FIG. 29 . 
     At the same time, two opposite second protective covers  3013  which may be pried are disposed at two sides of the hollow portion  3011 , the second protective covers  3013  are protruded and disposed on the cover  301 , the protruding part allows the part of the contact carrier exposed from the cover  201  to accommodate therein. Thusly when the function assistant modules  3020  are not assembled, as shown in  FIG. 23 , the part of the contact carrier exposed from the cover  301  is accommodated in the protruding part of the second protective cover  3013 , which effectively avoids human from pressing on the contact carrier to make the contactor conduct and damaging the contactor controlling equipment and affecting personal safety. 
     As shown from  FIG. 24  to  FIG. 26 , when it is needed to assemble two sets of the function assistant modules  3020 , the second protective covers  3013  are pried to form an assembling portion for assembling, at that moment, the first protective covers  3012  do not need to be pried. 
     As shown from  FIG. 27  to  FIG. 29 , when it is needed to assemble four sets of function assistant modules  3020 , two first protective covers  3012  at two sides of the hollow portion are further pried, which is easy to assemble and cost-saving. 
     The Fourth Technical Solution 
     Hereinafter the detail embodiment is illustrated accompanying with  FIG. 30  to  FIG. 35 . 
     As shown in  FIG. 30  to  FIG. 34 , the invention discloses a rail mounting structure of electric device, a mounting slot  4011  is formed on the base  401  of the electric device  40100 , and at least one first fixing clasp  4012  is formed at a side of the mounting slot  4011 . In the embodiment, there is only one first fixing clasp  4012 , and a first clasping slot  4013  is formed between the first fixing clasp  4012  and the base  401 . 
     A second fixing clasp  4014  is formed at another side of the mounting slot  4011 , and a second clasping slot  4015  is formed between the second fixing clasp  4014  and the base  401 . 
     A first limiting block  4016  and a second limiting block  4017  are formed at two sides of the second fixing clasp  4014 , respectively, a first limiting slot  4018  is formed between the first limiting block  4016  and the base  401 , and a second limiting slot  4019  is formed between the second limiting block  4017  and the base  401 . The first limiting slot  18  and the second limiting slot  19  are arc-shaped limiting slots ( 40181 ,  40191 ), and tapered guiding surfaces ( 40161 ,  40171 ) are formed respectively on the first limiting block  4016  and the second limiting block  4017 . 
     Two end of a snap spring  402  are disposed in the first limiting slot  4018  and the second limiting slot  4019 , respectively, and form linear contact with the side walls of the first limiting slot  18  and the second limiting slot  19 . The middle stage of the snap spring  402  is in the second clasping slot  4015 . 
     Two ends of the snap spring  402  linearly contact the side wall of the first limiting slot  4018  and the side wall of the second limiting slot  4019 , thusly the snap spring  402  is assembled stably and not easy to fall off. 
     In the embodiment, ribs ( 40182 ,  40192 ) are formed on the side walls of the first limiting slot  4018  and second limiting slot  4019 , the ribs ( 40182 ,  40192 ) are disposed above the snap spring  402 , which effectively avoid the falling off of the snap spring  402  due to warping of the two ends of the snap spring  402  under pressure. 
     As shown in  FIG. 34 , the width of the second clasping slot  4015  becomes wider gradually from inner part to the inserting opening  40151  of the snap spring  402 , which effectively avoid the falling off of the snap spring  402  due to warping of the middle stage of the snap spring  402  under pressure. 
     In the embodiment, the second fixing clasp  4014 , the first limiting block  4016  and the second limiting block  4017  are disposed as a reverse-trapezoid shape, correspondingly, the snap spring  402  is a reverse-trapezoid shape with a top opening, the middle stage thereof is straight or curved stage, the layout is compact in structure, and the rail is assembled stably. 
     In the embodiment, as shown in  FIG. 30 , the first limiting block  4016  and the second limiting block  4017  are formed by two parallel half-cylinders, and tapered surfaces are formed on each of the half-cylinders, respectively, to form the tapered guiding surfaces ( 40161 ,  40171 ). Correspondingly, two ends of the snap spring  402  are arc-shaped, and the arc-shaped stage matches the two parallel half-cylinders, which facilitates assembling. 
     when the electric device is mounted via the rail  403 , one side of the rail  403  is disposed in the first clasping slot  4013 , the other side is disposed in the second clasping slot  4015  and elastically contact the middle stage of the snap spring  402  to elastically deform the snap spring  402 , two ends of the snap spring  402  abut against the base  401 , a leaf spring principle of the snap spring  402  makes the rail  403  fixed stably. The rail  403  may be mounted from a side, which is easy to mount, and only one snap spring  402  is used to mount the electric device on the rail  403 , which saves manufacturing and usage cost. 
     During assembling the snap spring  402 , as shown in  FIG. 32 , a robot is used to dispose the snap spring  402  in the mounting slot  4011 , the middle stage of the snap spring  402  corresponds to the second fixing clasp  4014 , two ends of the snap spring  402  correspond to the first limiting block  4016  and the second limiting block  4017 , as shown in  FIG. 32 b   , the snap spring  402  is moved to get close to the second fixing clasp  4014 , to make the middle stage of the snap spring  402  disposed in the second clasping slot  4015 , and two ends of the snap spring  402  slide into the first limiting slot  4018  and the second limiting slot  4019  via the tapered guiding surfaces ( 40161 ,  40171 ), as shown in  FIG. 32 c   , the assembling process have no structure block, which may achieve automatic assembling and save manufacturing cost. 
     After assembling, if the assembling has error, the snap spring  402  is easy to take out, which is, only to lift two ends of the snap spring  402 , then slide the snap spring  402  out of the second clasping slot  4015 . 
     The invention takes a contactor as an example to illustrate the detailed structure, the rail mounting structure of the electric device may also be used in device such as the circuit breaker, the switch and the thermal relay. 
     Apparently, one of ordinary skill in the art can make various changes and modifications to the present disclosure without departing from the spirit and scope of the invention. Thus, the present disclosure intends to encompass such changes and modifications provided that those changes and modifications fall within the scope of claims of the present invention and equivalents thereof.